WorldWideScience

Sample records for channel preferentially aggregates

  1. Schemes for aggregating preferential tariffs in agriculture,export volume effects and African LDCs

    DEFF Research Database (Denmark)

    Yu, Wusheng

    Trade-weighted aggregated tariffs (TWPT) are often used in analyzing the issues of erosion of non-reciprocal preferences. This paper argues that commonly used TWPTs under-estimate the true protection on imports originated from preference-receiving countries, including LDCs. When used in numerical...... simulations of preference erosion and expansion scenarios, the TWPTs tend to incorrectly downplay preference erosion effect of MFN tariff cuts, and understate the export promotion effect of expanding preferences. In light of these claims, an alternative aggregation scheme is developed to calculate aggregated...... preferential tariffs imposed by a number of developed countries on African LDCs. These are shown to be higher than the TWPTs aggregated from the same disaggregated tariff data set. Numerical simulations conducted with the two sets of aggregated tariffs confirm the two claims and suggest that TWPTs may lead...

  2. Proteins with Intrinsically Disordered Domains Are Preferentially Recruited to Polyglutamine Aggregates.

    Directory of Open Access Journals (Sweden)

    Maggie P Wear

    Full Text Available Intracellular protein aggregation is the hallmark of several neurodegenerative diseases. Aggregates formed by polyglutamine (polyQ-expanded proteins, such as Huntingtin, adopt amyloid-like structures that are resistant to denaturation. We used a novel purification strategy to isolate aggregates formed by human Huntingtin N-terminal fragments with expanded polyQ tracts from both yeast and mammalian (PC-12 cells. Using mass spectrometry we identified the protein species that are trapped within these polyQ aggregates. We found that proteins with very long intrinsically-disordered (ID domains (≥ 100 amino acids and RNA-binding proteins were disproportionately recruited into aggregates. The removal of the ID domains from selected proteins was sufficient to eliminate their recruitment into polyQ aggregates. We also observed that several neurodegenerative disease-linked proteins were reproducibly trapped within the polyQ aggregates purified from mammalian cells. Many of these proteins have large ID domains and are found in neuronal inclusions in their respective diseases. Our study indicates that neurodegenerative disease-associated proteins are particularly vulnerable to recruitment into polyQ aggregates via their ID domains. Also, the high frequency of ID domains in RNA-binding proteins may explain why RNA-binding proteins are frequently found in pathological inclusions in various neurodegenerative diseases.

  3. Combination of preferential CO oxidation and methanation in hybrid MCR (micro-channel reactor) for CO clean-up

    International Nuclear Information System (INIS)

    CO in the hydrogen stream must be reduced to extremely low levels, under 10 ppm, because the Pt electrode is detrimentally affected by residual CO in the H2 stream. Therefore removal of carbon monoxide from the H2-rich stream during fuel generation from hydrocarbons is a critical challenge, especially for PEMFC (proton exchange membrane fuel cell) applications. Herein, CO an initial concentration of 1.0 vol.% was successfully removed from a H2-rich stream to a residual level below 10 ppm, within the wide operating temperature range from 92 to 235 °C by utilizing a hybrid channel reactor comprising a micro-channel heat exchanger and mini-packed bed reactor. The mini-packed bed reactor contained two kinds of catalysts that promote preferential oxidation and methanation of CO in series. The HMCR (hybrid micro- and mini- channel reactor) offers not only ultimately safe operation but also easy scale-up and is adaptable to mass production of CO clean-up units. - Highlights: • Hybrid reactor (micro-channel heat exchanger/mini-packed bed reactor) developed. • Serial bi-catalysis allowed preferential oxidation and methanation of CO. • PrOx-methanation catalysts had higher activity in HMCR, with 143 °C HMCR window. • CO below 10 ppm achieved by combined PrOx and methanation in HMCR system. • Lower operation temperature and wider temperature range for HMCR achieved

  4. Cardiac ATP-sensitive K+ channels. Evidence for preferential regulation by glycolysis

    OpenAIRE

    1989-01-01

    The ability of glycolysis, oxidative phosphorylation, the creatine kinase system, and exogenous ATP to suppress ATP-sensitive K+ channels and prevent cell shortening were compared in patch-clamped single guinea pig ventricular myocytes. In cell-attached patches on myocytes permeabilized at one end with saponin, ATP-sensitive K+ channels were activated by removing ATP from the bath, and could be closed equally well by exogenous ATP or substrates for endogenous ATP production by glycolysis (wit...

  5. Optimization-Based Channel Constrained Data Aggregation Routing Algorithms in Multi-Radio Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Hong-Hsu Yen

    2009-06-01

    Full Text Available In wireless sensor networks, data aggregation routing could reduce the number of data transmissions so as to achieve energy efficient transmission. However, data aggregation introduces data retransmission that is caused by co-channel interference from neighboring sensor nodes. This kind of co-channel interference could result in extra energy consumption and significant latency from retransmission. This will jeopardize the benefits of data aggregation. One possible solution to circumvent data retransmission caused by co-channel interference is to assign different channels to every sensor node that is within each other’s interference range on the data aggregation tree. By associating each radio with a different channel, a sensor node could receive data from all the children nodes on the data aggregation tree simultaneously. This could reduce the latency from the data source nodes back to the sink so as to meet the user’s delay QoS. Since the number of radios on each sensor node and the number of non-overlapping channels are all limited resources in wireless sensor networks, a challenging question here is to minimize the total transmission cost under limited number of non-overlapping channels in multi-radio wireless sensor networks. This channel constrained data aggregation routing problem in multi-radio wireless sensor networks is an NP-hard problem. I first model this problem as a mixed integer and linear programming problem where the objective is to minimize the total transmission subject to the data aggregation routing, channel and radio resources constraints. The solution approach is based on the Lagrangean relaxation technique to relax some constraints into the objective function and then to derive a set of independent subproblems. By optimally solving these subproblems, it can not only calculate the lower bound of the original primal problem but also provide useful information to get the primal feasible solutions. By incorporating these

  6. Price Level vs. Nominal Income Targeting: Aggregate Demand Shocks and the Cost Channel of Monetary Policy Transmission

    OpenAIRE

    Malik, Hamza

    2005-01-01

    This paper incorporates both the traditional aggregate demand-interest rate channel and the cost channel of monetary policy in a baseline ‘new Keynesian’ model and study two targeting regimes --- price-level targeting and nominal income targeting. In light of empirical considerations, alternative specifications for the aggregate demand and aggregate supply side of the economy also considered. The main result is that the cost channel matters: in case of a moderate policy response and with the ...

  7. Stress wave communication in concrete: I. Characterization of a smart aggregate based concrete channel

    Science.gov (United States)

    Siu, Sam; Ji, Qing; Wu, Wenhao; Song, Gangbing; Ding, Zhi

    2014-12-01

    In this paper, we explore the characteristics of a concrete block as a communication medium with piezoelectric transducers. Lead zirconate titanate (PZT) is a piezoceramic material used in smart materials intended for structural health monitoring (SHM). Additionally, a PZT based smart aggregate (SA) is capable of implementing stress wave communications which is utilized for investigating the properties of an SA based concrete channel. Our experiments characterize single-input single-output and multiple-input multiple-output (MIMO) concrete channels in order to determine the potential capacity limits of SAs for stress wave communication. We first provide estimates and validate the concrete channel response. Followed by a theoretical upper bound for data rate capacity of our two channels, demonstrating a near-twofold increase in channel capacity by utilizing multiple transceivers to form an MIMO system. Our channel modeling techniques and results are also helpful to researchers using SAs with regards to SHM, energy harvesting and stress wave communications.

  8. Stress wave communication in concrete: I. Characterization of a smart aggregate based concrete channel

    International Nuclear Information System (INIS)

    In this paper, we explore the characteristics of a concrete block as a communication medium with piezoelectric transducers. Lead zirconate titanate (PZT) is a piezoceramic material used in smart materials intended for structural health monitoring (SHM). Additionally, a PZT based smart aggregate (SA) is capable of implementing stress wave communications which is utilized for investigating the properties of an SA based concrete channel. Our experiments characterize single-input single-output and multiple-input multiple-output (MIMO) concrete channels in order to determine the potential capacity limits of SAs for stress wave communication. We first provide estimates and validate the concrete channel response. Followed by a theoretical upper bound for data rate capacity of our two channels, demonstrating a near-twofold increase in channel capacity by utilizing multiple transceivers to form an MIMO system. Our channel modeling techniques and results are also helpful to researchers using SAs with regards to SHM, energy harvesting and stress wave communications. (paper)

  9. Asymmetry of parental origin in long QT syndrome: preferential maternal transmission of KCNQ1 variants linked to channel dysfunction.

    Science.gov (United States)

    Itoh, Hideki; Berthet, Myriam; Fressart, Véronique; Denjoy, Isabelle; Maugenre, Svetlana; Klug, Didier; Mizusawa, Yuka; Makiyama, Takeru; Hofman, Nynke; Stallmeyer, Birgit; Zumhagen, Sven; Shimizu, Wataru; Wilde, Arthur A M; Schulze-Bahr, Eric; Horie, Minoru; Tezenas du Montcel, Sophie; Guicheney, Pascale

    2016-08-01

    Transmission distortion of disease-causing alleles in long QT syndrome (LQTS) has been reported, suggesting a potential role of KCNQ1 and KCNH2 in reproduction. This study sought to investigate parental transmission in LQTS families according to ethnicity, gene loci (LQT1-3: KCNQ1, KCNH2, and SCN5A) or severity of channel dysfunction. We studied 3782 genotyped members from 679 European and Japanese LQTS families (2748 carriers). We determined grandparental and parental origins of variant alleles in 1903 children and 624 grandchildren, and the grandparental origin of normal alleles in healthy children from 44 three-generation control families. LQTS alleles were more of maternal than paternal origin (61 vs 39%, Pgrandmother alleles. For LQT1, maternal transmission differs according to the variant level of dysfunction with 68% of maternal transmission for dominant negative or unknown functional consequence variants vs 58% for non-dominant negative and variants leading to haploinsufficiency, P<0.01; however, for LQT2 or LQT3 this association was not significant. An excess of disease-causing alleles of maternal origin, most pronounced in LQT1, was consistently found across ethnic groups. This observation does not seem to be linked to an imbalance in transmission of the LQTS subtype-specific grandparental allele, but to the potential degree of potassium channel dysfunction. PMID:26669661

  10. Investigation of structure-spectroscopy-function relationship of two-dimensional J-aggregates of tetrachlorobenzimidazolocarbocyanine preferentially oriented in poly-vinyl-alcohol thin films

    Energy Technology Data Exchange (ETDEWEB)

    Guelen, Demet [Physics Department, Middle East Technical University, 06531 Ankara (Turkey)], E-mail: dgul@metu.edu.tr; Atasoylu, Onur [Chemistry Department, Izmir Institute of Technology, Urla-35430, Izmir (Turkey); Ozcelik, Serdar [Chemistry Department, Izmir Institute of Technology, Urla-35430, Izmir (Turkey)], E-mail: serdarozcelik@iyte.edu.tr

    2009-01-07

    The structure-spectroscopy-function relationship of 1,1',3,3'-tetraethyl-5,5',6,6'-tetrachlorobenzimidazolocarbocyanine (TTBC) aggregates is studied using a combination of experimental and theoretical techniques. The aggregates are macroscopically aligned in poly-vinyl-alcohol thin films by vertical spin coating. Angular dependence of the UV-Vis spectra is measured at eleven different orientations between the electric field polarization and the macroscopic alignment axis. The aggregates are characterized by a pair of Davydov split bands with opposite polarization behaviors: an H-band (505 nm) and a J-band (594 nm) polarized respectively, close to being parallel and perpendicular to the alignment axis. Spectral response is interpreted via simulations within the Frenkel exciton formalism. TTBC aggregates are shown to assume very similar internal molecular packing (herringbone) and dynamics of excited states (phonon-assisted intraband and interband relaxations) in ionic aqueous solution and in thin films. The general conclusions on the structure-spectroscopy-function relationship are expected to hold for other cyanine aggregates with the same generic spectral features.

  11. Investigation of structure-spectroscopy-function relationship of two-dimensional J-aggregates of tetrachlorobenzimidazolocarbocyanine preferentially oriented in poly-vinyl-alcohol thin films

    International Nuclear Information System (INIS)

    The structure-spectroscopy-function relationship of 1,1',3,3'-tetraethyl-5,5',6,6'-tetrachlorobenzimidazolocarbocyanine (TTBC) aggregates is studied using a combination of experimental and theoretical techniques. The aggregates are macroscopically aligned in poly-vinyl-alcohol thin films by vertical spin coating. Angular dependence of the UV-Vis spectra is measured at eleven different orientations between the electric field polarization and the macroscopic alignment axis. The aggregates are characterized by a pair of Davydov split bands with opposite polarization behaviors: an H-band (505 nm) and a J-band (594 nm) polarized respectively, close to being parallel and perpendicular to the alignment axis. Spectral response is interpreted via simulations within the Frenkel exciton formalism. TTBC aggregates are shown to assume very similar internal molecular packing (herringbone) and dynamics of excited states (phonon-assisted intraband and interband relaxations) in ionic aqueous solution and in thin films. The general conclusions on the structure-spectroscopy-function relationship are expected to hold for other cyanine aggregates with the same generic spectral features

  12. Study of the interaction of unaggregated and aggregated amyloid β protein (10-21) with outward potassium channel

    Institute of Scientific and Technical Information of China (English)

    ZHANG; ChaoFeng; FAN; Li; YANG; Pin

    2007-01-01

    Metal ion-induced aggregation of Aβinto insoluble plaques is a central factor in Alzheimer's disease. Zn2+ is the only physiologically available transition metal ion responsible for aggregating Aβ at pH 7.4. To make it clear that the neurotoxicity of Zn2+-induced aggregation of Aβ on neurons is the key to understand Aβ mechanism of action further. In this paper, we choose Aβ (10-21) as the model fragment to research hippocampal CA1 pyramidal neurons. For the first time, we adopt the combination of spectral analysis with patch-clamp technique for the preliminary study of the mutual relations of Zn2+, Aβ and ion channel from the cell level. The following expounds upon the effects and mode of action of two forms (unaggregated and aggregated) of Aβ (10-21) on hippocampus outward potassium channel three processes (activation, inactivation and reactivation). It also shows the molecular mechanics of AD from the channel level. These results are significant for the further study of Aβ nosogenesis and the development of new types of target drugs for the treatment of AD.

  13. Preferential sorption versus preferential permeability in pervaporation

    NARCIS (Netherlands)

    Mulder, M.H.V.; Franken, T.; Smolders, C.A.

    1985-01-01

    Transport of liquids by pervaporation takes place by a solution—diffusion mechanism. In order to investigate the “solution part” of this transport model, preferential sorption has been compared with preferential permeability. Sorption equilibria and pervaporation experiments for the systems water—et

  14. Probabilistic human health risk assessment of degradation-related chemical mixtures in heterogeneous aquifers: Risk statistics, hot spots, and preferential channels

    Science.gov (United States)

    Henri, Christopher V.; Fernández-Garcia, Daniel; Barros, Felipe P. J.

    2015-06-01

    The increasing presence of toxic chemicals released in the subsurface has led to a rapid growth of social concerns and the need to develop and employ models that can predict the impact of groundwater contamination on human health risk under uncertainty. Monitored natural attenuation is a common remediation action in many contamination cases. However, natural attenuation can lead to the production of daughter species of distinct toxicity that may pose challenges in pollution management strategies. The actual threat that these contaminants pose to human health depends on the interplay between the complex structure of the geological media and the toxicity of each pollutant byproduct. This work addresses human health risk for chemical mixtures resulting from the sequential degradation of a contaminant (such as a chlorinated solvent) under uncertainty through high-resolution three-dimensional numerical simulations. We systematically investigate the interaction between aquifer heterogeneity, flow connectivity, contaminant injection model, and chemical toxicity in the probabilistic characterization of health risk. We illustrate how chemical-specific travel times control the regime of the expected risk and its corresponding uncertainties. Results indicate conditions where preferential flow paths can favor the reduction of the overall risk of the chemical mixture. The overall human risk response to aquifer connectivity is shown to be nontrivial for multispecies transport. This nontriviality is a result of the interaction between aquifer heterogeneity and chemical toxicity. To quantify the joint effect of connectivity and toxicity in health risk, we propose a toxicity-based Damköhler number. Furthermore, we provide a statistical characterization in terms of low-order moments and the probability density function of the individual and total risks.

  15. Cytoplasmic location of α1A voltage-gated calcium channel C-terminal fragment (Cav2.1-CTF) aggregate is sufficient to cause cell death.

    Science.gov (United States)

    Takahashi, Makoto; Obayashi, Masato; Ishiguro, Taro; Sato, Nozomu; Niimi, Yusuke; Ozaki, Kokoro; Mogushi, Kaoru; Mahmut, Yasen; Tanaka, Hiroshi; Tsuruta, Fuminori; Dolmetsch, Ricardo; Yamada, Mitsunori; Takahashi, Hitoshi; Kato, Takeo; Mori, Osamu; Eishi, Yoshinobu; Mizusawa, Hidehiro; Ishikawa, Kinya

    2013-01-01

    The human α1A voltage-dependent calcium channel (Cav2.1) is a pore-forming essential subunit embedded in the plasma membrane. Its cytoplasmic carboxyl(C)-tail contains a small poly-glutamine (Q) tract, whose length is normally 4∼19 Q, but when expanded up to 20∼33Q, the tract causes an autosomal-dominant neurodegenerative disorder, spinocerebellar ataxia type 6 (SCA6). A recent study has shown that a 75-kDa C-terminal fragment (CTF) containing the polyQ tract remains soluble in normal brains, but becomes insoluble mainly in the cytoplasm with additional localization to the nuclei of human SCA6 Purkinje cells. However, the mechanism by which the CTF aggregation leads to neurodegeneration is completely elusive, particularly whether the CTF exerts more toxicity in the nucleus or in the cytoplasm. We tagged recombinant (r)CTF with either nuclear-localization or nuclear-export signal, created doxycyclin-inducible rat pheochromocytoma (PC12) cell lines, and found that the CTF is more toxic in the cytoplasm than in the nucleus, the observations being more obvious with Q28 (disease range) than with Q13 (normal-length). Surprisingly, the CTF aggregates co-localized both with cAMP response element-binding protein (CREB) and phosphorylated-CREB (p-CREB) in the cytoplasm, and Western blot analysis showed that the quantity of CREB and p-CREB were both decreased in the nucleus when the rCTF formed aggregates in the cytoplasm. In human brains, polyQ aggregates also co-localized with CREB in the cytoplasm of SCA6 Purkinje cells, but not in other conditions. Collectively, the cytoplasmic Cav2.1-CTF aggregates are sufficient to cause cell death, and one of the pathogenic mechanisms may be abnormal CREB trafficking in the cytoplasm and reduced CREB and p-CREB levels in the nuclei. PMID:23505410

  16. Cytoplasmic location of α1A voltage-gated calcium channel C-terminal fragment (Cav2.1-CTF aggregate is sufficient to cause cell death.

    Directory of Open Access Journals (Sweden)

    Makoto Takahashi

    Full Text Available The human α1A voltage-dependent calcium channel (Cav2.1 is a pore-forming essential subunit embedded in the plasma membrane. Its cytoplasmic carboxyl(C-tail contains a small poly-glutamine (Q tract, whose length is normally 4∼19 Q, but when expanded up to 20∼33Q, the tract causes an autosomal-dominant neurodegenerative disorder, spinocerebellar ataxia type 6 (SCA6. A recent study has shown that a 75-kDa C-terminal fragment (CTF containing the polyQ tract remains soluble in normal brains, but becomes insoluble mainly in the cytoplasm with additional localization to the nuclei of human SCA6 Purkinje cells. However, the mechanism by which the CTF aggregation leads to neurodegeneration is completely elusive, particularly whether the CTF exerts more toxicity in the nucleus or in the cytoplasm. We tagged recombinant (rCTF with either nuclear-localization or nuclear-export signal, created doxycyclin-inducible rat pheochromocytoma (PC12 cell lines, and found that the CTF is more toxic in the cytoplasm than in the nucleus, the observations being more obvious with Q28 (disease range than with Q13 (normal-length. Surprisingly, the CTF aggregates co-localized both with cAMP response element-binding protein (CREB and phosphorylated-CREB (p-CREB in the cytoplasm, and Western blot analysis showed that the quantity of CREB and p-CREB were both decreased in the nucleus when the rCTF formed aggregates in the cytoplasm. In human brains, polyQ aggregates also co-localized with CREB in the cytoplasm of SCA6 Purkinje cells, but not in other conditions. Collectively, the cytoplasmic Cav2.1-CTF aggregates are sufficient to cause cell death, and one of the pathogenic mechanisms may be abnormal CREB trafficking in the cytoplasm and reduced CREB and p-CREB levels in the nuclei.

  17. Cyclic 3'-5'-adenosine monophosphate binds to annexin I and regulates calcium-dependent membrane aggregation and ion channel activity.

    Science.gov (United States)

    Cohen, B E; Lee, G; Arispe, N; Pollard, H B

    1995-12-27

    The annexin (Anx) gene family comprises a set of calcium-dependent membrane binding proteins, which have been implicated in a wide variety of cellular processes including membrane fusion and calcium channel activity. We report here that cAMP activates Ca(2+)-dependent aggregation of both phosphatidylserine (PS) liposomes and bovine chromaffin granules driven by [des 1-12]annexin I (lipocortin I, Anx1). The mechanism of cAMP action involves an increase in AnxI-dependent cooperativity on the rate of such a reaction without affecting the corresponding k1/2 values. Cyclic AMP causes the values of the Hill coefficient (nH) for AnxI to change from 3 to 6 in both PS liposomes and chromaffin granules. By contrast, ATP inhibits the rate of aggregation activity without affecting the cooperativity or the extent of aggregation process. We were also able to photolabel Anx1 specifically with an 8-azido analogue of cAMP by a calcium-independent process. Such a process is saturable, yielding a Kd = 0.8 microM by Scatchard analysis. Specific displacement occurs in the presence of cAMP and ATP. Finally, we found that cAMP alters the conductance of calcium channels formed by AnxI in planar lipid bilayers. We interpret these data to indicate that AnxI binds both calcium and cAMP independently, and that both actions have functional consequences. This is the first report of a nucleotide binding function for a member of the annexin gene family.

  18. Against Preferential Treatment.

    Science.gov (United States)

    Kekes, John

    1997-01-01

    Argues that preferential treatment of women and minorities in the selection of college faculty elevates a form of corruption to standard administrative practice by including people in academic life on the basis of characteristics irrelevant to teaching and research; and previous unjust treatment is inadequate justification for preferential…

  19. Quantifying flow retention due to vegetation in an earthen experimental channel using the Aggregated Dead Zone (ADZ) dilution approach

    NARCIS (Netherlands)

    Carling, Paul; Kleinhans, Maarten; Leyland, Julian; Besozzi, Louison; Duranton, Pierre; Trieu, Hai; Teske, Roy

    2014-01-01

    Understanding of flow resistance of forested floodplains is essential for floodplain flow routing and floodplain reforestation projects. Although the flow resistance of grass-lined channels is well-known, flow retention due to flow-blocking by trees is poorly understood. Flow behaviour through tree-

  20. TRAFFIC OFFLOADING IMPACT ON THE PERFORMANCE OF CHANNEL-AWARE/QOS-AWARE SCHEDULING ALGORITHMS FOR VIDEO-APPLICATIONS OVER LTE-A HETNETS USING CARRIER AGGREGATION

    Directory of Open Access Journals (Sweden)

    Najem N. Sirhan

    2015-09-01

    Full Text Available Long Term Evolution (LTE is defined by the Third Generation Partnership Project (3GPP standards as Release 8/9. The LTE supports at max 20 MHz channel bandwidth for a carrier. The number of LTE users and their applications are increasing, which increases the demand on the system BW. A new feature of the LTE-Advanced (LTE-A which is defined in the 3GPP standards as Release 10/11 is called Carrier Aggregation (CA, this feature allows the network to aggregate more carriers in-order to provide a higher bandwidth. Carrier Aggregation has three main cases: Intra-band contiguous, Intra-band non-contiguous, Inter-band contiguous. In addition to the Carrier Aggregation feature, LTE-A supports Heterogeneous Networks (HetNets. HetNets consists of a mix of macro-cells, remote radio heads, and low power nodes such as pico-cells, and femto-cells. HetNets allow cellular network operators to support higher data traffic by offloading it to a smaller cells such as femto-cells. The aim of this paper is to evaluate the Quality of Service (QoS performance of the Modified Largest Weighted Delay First (MLWDF, the Exponential Rule (Exp-Rule, and the Logarithmic Rule (Log-Rule scheduling algorithms while offloading 50% of the macro-cell's traffic to five femto-cells, 100% of the macro-cell's traffic to five femto-cells, 100% of the macro-cell's traffic to ten femto-cells, and to compare it with the case in-which traffic offloading is not applied. The QoS performance evaluation is based on the system's average throughput, Packet Loss Rate(PLR, average packet delay, and fairness among users. The LTE-Sim-5 with modifications is used in the simulation process. Simulation results show that offloading 100% of the Macro-cell's traffic to five femtocells had the highest maximum throughput, and the best PLR values especially when using the Log-Rule, in-which using it maintained the PLR values around 0.15 despite increasing the number of users. The least average packet delay was

  1. Research Progress of Self-initiated Aggregating Proppant in Channel Fracturing Technique%高通道压裂自聚性支撑剂研究进展

    Institute of Scientific and Technical Information of China (English)

    浮历沛; 张贵才; 张弛; 葛际江; 廖凯丽; 李田靓

    2016-01-01

    针对非常规油气资源难以开采且多依赖水力压裂增产措施的特点,结合近几年刚刚兴起的高通道压裂技术,介绍了国外支撑剂自聚调控技术的最新进展。重点综述了自聚性支撑剂表面处理技术、表面改性机理、支撑剂在线涂层工艺的研究现状,指出了高通道压裂自聚性支撑剂亟需解决的问题及发展趋势。图8参27%On account of the difficulties confronted with the unconventional hydrocarbon resources during the exploration and development progress,which often depends on the hydraulic fracture stimulation,combining with the channel fracturing technique rising up in the past several years,the latest advances of self-initiated aggregating proppant(SIAP)overseas were introduced. The present research status of SIAP,surface modification mechanism,and on-the-fly coating technology was mainly summarized. The troubles that SIAP faces and the future trends were also pointed out.

  2. A novel µ-conopeptide, CnIIIC, exerts potent and preferential inhibition of NaV1.2/1.4 channels and blocks neuronal nicotinic acetylcholine receptors

    NARCIS (Netherlands)

    Favreau, P.; Benoit, E.; Hocking, H.G.; Carlier, L.P.A.; D’ hoedt, D.; Leipold, E.; Markgraf, R.; Boelens, R.; Molgo, J.

    2012-01-01

    BACKGROUND AND PURPOSE The µ-conopeptide family is defined by its ability to block voltage-gated sodium channels (VGSCs), a property that can be used for the development of myorelaxants and analgesics. We characterized the pharmacology of a new µ-conopeptide (µ-CnIIIC) on a range of preparations and

  3. Hamiltonian Dynamics of Preferential Attachment

    CERN Document Server

    Zuev, Konstantin; Krioukov, Dmitri

    2015-01-01

    Prediction and control of network dynamics are grand-challenge problems in network science. The lack of understanding of fundamental laws driving the dynamics of networks is among the reasons why many practical problems of great significance remain unsolved for decades. Here we study the dynamics of networks evolving according to preferential attachment, known to approximate well the large-scale growth dynamics of a variety of real networks. We show that this dynamics is Hamiltonian, thus casting the study of complex networks dynamics to the powerful canonical formalism, in which the time evolution of a dynamical system is described by Hamilton's equations. We derive the explicit form of the Hamiltonian that governs network growth in preferential attachment. This Hamiltonian turns out to be nearly identical to graph energy in the configuration model, which shows that the ensemble of random graphs generated by preferential attachment is nearly identical to the ensemble of random graphs with scale-free degree d...

  4. Diameters in preferential attachment models

    NARCIS (Netherlands)

    Dommers, S.; Van der Hofstad, R.; Hooghiemstra, G.

    2010-01-01

    In this paper, we investigate the diameter in preferential attachment (PA-) models, thus quantifying the statement that these models are small worlds. The models studied here are such that edges are attached to older vertices proportional to the degree plus a constant, i.e., we consider affine PA-mo

  5. Transition probability and preferential gauge

    OpenAIRE

    Chen, C.Y.

    1999-01-01

    This paper is concerned with whether or not the preferential gauge can ensure the uniqueness and correctness of results obtained from the standard time-dependent perturbation theory, in which the transition probability is formulated in terms of matrix elements of Hamiltonian.

  6. A preferential flow leaching index

    NARCIS (Netherlands)

    McGrath, G.S.; Hinz, C.; Sivapalan, M.

    2009-01-01

    The experimental evidence suggests that for many chemicals surface runoff and rapid preferential flow through the shallow unsaturated zone are significant pathways for transport to streams and groundwater. The signature of this is the episodic and pulsed leaching of these chemicals. The driver for t

  7. Diameters in preferential attachment models

    OpenAIRE

    Dommers, S.; van der Hofstad, R.; Hooghiemstra, G.

    2010-01-01

    In this paper, we investigate the diameter in preferential attachment (PA-) models, thus quantifying the statement that these models are small worlds. The models studied here are such that edges are attached to older vertices proportional to the degree plus a constant, i.e., we consider affine PA-models. There is a substantial amount of literature proving that, quite generally, PA-graphs possess power-law degree sequences with a power-law exponent \\tau>2. We prove that the diameter of the PA-...

  8. Aggregate productivity and aggregate technology

    OpenAIRE

    Susanto Basu; John G. Fernald

    1997-01-01

    Aggregate productivity and aggregate technology are meaningful but distinct concepts. We show that a slightly-modified Solow productivity residual measures changes in economic welfare, even when productivity and technology differ because of distortions such as imperfect competition. We then present a general accounting framework that identifies several new non-technological gaps between productivity and technology, gaps reflecting imperfections and frictions in output and factor markets. Empi...

  9. Information filtering via preferential diffusion

    CERN Document Server

    Lu, Linyuan

    2011-01-01

    Recommender systems have shown great potential to address information overload problem, namely to help users in finding interesting and relevant objects within a huge information space. Some physical dynamics, including heat conduction process and mass or energy diffusion on networks, have recently found applications in personalized recommendation. Most of the previous studies focus overwhelmingly on recommendation accuracy as the only important factor, while overlook the significance of diversity and novelty which indeed provide the vitality of the system. In this paper, we propose a recommendation algorithm based on the preferential diffusion process on user-object bipartite network. Numerical analyses on two benchmark datasets, MovieLens and Netflix, indicate that our method outperforms the state-of-the-art methods. Specifically, it can not only provide more accurate recommendations, but also generate more diverse and novel recommendations by accurately recommending unpopular objects.

  10. Information filtering via preferential diffusion

    Science.gov (United States)

    Lü, Linyuan; Liu, Weiping

    2011-06-01

    Recommender systems have shown great potential in addressing the information overload problem, namely helping users in finding interesting and relevant objects within a huge information space. Some physical dynamics, including the heat conduction process and mass or energy diffusion on networks, have recently found applications in personalized recommendation. Most of the previous studies focus overwhelmingly on recommendation accuracy as the only important factor, while overlooking the significance of diversity and novelty that indeed provide the vitality of the system. In this paper, we propose a recommendation algorithm based on the preferential diffusion process on a user-object bipartite network. Numerical analyses on two benchmark data sets, MovieLens and Netflix, indicate that our method outperforms the state-of-the-art methods. Specifically, it can not only provide more accurate recommendations, but also generate more diverse and novel recommendations by accurately recommending unpopular objects.

  11. Coexistence in preferential attachment networks

    CERN Document Server

    Antunović, Tonći; Racz, Miklos Z

    2013-01-01

    Competition in markets is ubiquitous: cell-phone providers, computer manufacturers, and sport gear brands all vie for customers. Though several coexisting competitors are often observed in empirical data, many current theoretical models of competition on small-world networks predict a single winner taking over the majority of the network. We introduce a new model of product adoption that focuses on word-of-mouth recommendations to provide an explanation for this coexistence of competitors. The key property of our model is that customer choices evolve simultaneously with the network of customers. When a new node joins the network, it chooses neighbors according to preferential attachment, and then chooses its type based on the number of initial neighbors of each type. This can model a new cell-phone user choosing a cell-phone provider, a new student choosing a laptop, or a new athletic team member choosing a gear provider. We provide a detailed analysis of the new model; in particular, we determine the possibl...

  12. Hamiltonian dynamics of preferential attachment

    International Nuclear Information System (INIS)

    Prediction and control of network dynamics are grand-challenge problems in network science. The lack of understanding of fundamental laws driving the dynamics of networks is among the reasons why many practical problems of great significance remain unsolved for decades. Here we study the dynamics of networks evolving according to preferential attachment (PA), known to approximate well the large-scale growth dynamics of a variety of real networks. We show that this dynamics is Hamiltonian, thus casting the study of complex networks dynamics to the powerful canonical formalism, in which the time evolution of a dynamical system is described by Hamilton’s equations. We derive the explicit form of the Hamiltonian that governs network growth in PA. This Hamiltonian turns out to be nearly identical to graph energy in the configuration model, which shows that the ensemble of random graphs generated by PA is nearly identical to the ensemble of random graphs with scale-free degree distributions. In other words, PA generates nothing but random graphs with power-law degree distribution. The extension of the developed canonical formalism for network analysis to richer geometric network models with non-degenerate groups of symmetries may eventually lead to a system of equations describing network dynamics at small scales. (paper)

  13. Emergence of tempered preferential attachment from optimization

    OpenAIRE

    D'Souza, Raissa M.; Borgs, Christian; Chayes, Jennifer T.; Berger, Noam; Kleinberg, Robert D.

    2007-01-01

    We show how preferential attachment can emerge in an optimization framework, resolving a long-standing theoretical controversy. We also show that the preferential attachment model so obtained has two novel features, saturation and viability, which have natural interpretations in the underlying network and lead to a power-law degree distribution with exponential cutoff. Moreover, we consider a generalized version of this preferential attachment model with independent saturation and viability, ...

  14. 15 CFR 700.14 - Preferential scheduling.

    Science.gov (United States)

    2010-01-01

    ...) BUREAU OF INDUSTRY AND SECURITY, DEPARTMENT OF COMMERCE NATIONAL SECURITY INDUSTRIAL BASE REGULATIONS DEFENSE PRIORITIES AND ALLOCATIONS SYSTEM Industrial Priorities § 700.14 Preferential scheduling. (a)...

  15. Synchronizability Analysis of Harmonious Unification Hybrid Preferential Model

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The harmonious unification hybrid preferential model uses the dr ratio to adjust the proportion of deterministic preferential attachment and random preferential attachment, enriched the only deterministic preferential network model,

  16. Construction aggregates

    Science.gov (United States)

    Nelson, T.I.; Bolen, W.P.

    2007-01-01

    Construction aggregates, primarily stone, sand and gravel, are recovered from widespread naturally occurring mineral deposits and processed for use primarily in the construction industry. They are mined, crushed, sorted by size and sold loose or combined with portland cement or asphaltic cement to make concrete products to build roads, houses, buildings, and other structures. Much smaller quantities are used in agriculture, cement manufacture, chemical and metallurgical processes, glass production and many other products.

  17. A generalized theory of preferential linking

    CERN Document Server

    Hu, Haibo; Liu, Xuan

    2013-01-01

    There are diverse mechanisms driving the evolution of social networks. A key open question dealing with understanding their evolution is: How various preferential linking mechanisms produce networks with different features? In this paper we first empirically study preferential linking phenomena in an evolving online social network, find and validate the linear preference. We propose an analyzable model which captures the real growth process of the network and reveals the underlying mechanism dominating its evolution. Furthermore based on preferential linking we propose a generalized model reproducing the evolution of online social networks, present unified analytical results describing network characteristics for 27 preference scenarios, and explore the relation between preferential linking mechanism and network features. We find that within the framework of preferential linking analytical degree distributions can only be the combinations of finite kinds of functions which are related to rational, logarithmic...

  18. The Earliest Ion Channels

    Science.gov (United States)

    Pohorille, A.; Wilson, M. A.; Wei, C.

    2009-12-01

    Supplying protocells with ions required assistance from channels spanning their membrane walls. The earliest channels were most likely short proteins that formed transmembrane helical bundles surrounding a water-filled pore. These simple aggregates were capable of transporting ions with efficiencies comparable to those of complex, contemporary ion channels. Channels with wide pores exhibited little ion selectivity but also imposed only modest constraints on amino acid sequences of channel-forming proteins. Channels with small pores could have been selective but also might have required a more precisely defined sequence of amino acids. In contrast to modern channels, their protocellular ancestors had only limited capabilities to regulate ion flux. It is postulated that subsequent evolution of ion channels progressed primarily to acquire precise regulation, and not high efficiency or selectivity. It is further proposed that channels and the surrounding membranes co-evolved.

  19. Air blast freezing of fruit pulp models in commercial boxes: influence of preferential channels in the bed on freezing times estimating Congelamento de modelos de polpas de frutas com ar forçado: influência de canais preferenciais no leito sobre as estimativas dos tempos de congelamento

    Directory of Open Access Journals (Sweden)

    Jaime Vilela de Resende

    2002-12-01

    Full Text Available The freezing times of fruit pulp models packed and conditioned in multi-layered boxes were evaluated under conditions similar to those employed commercially. Estimating the freezing time is a difficult practice due to the presence of significant voids in the boxes, whose influence may be analyzed by means of various methods. In this study, a procedure for estimating freezing time by using the models described in the literature was compared with experimental measurements by collecting time/temperature data. The following results show that the airflow through packages is a significant parameter for freezing time estimation. When the presence of preferential channels was considered, the predicted freezing time in the models could be 10% lower than the experimental values, depending on the method. The isotherms traced as a function of the location of the samples inside the boxes showed the displacement of the thermal center in relation to the geometric center of the product.Os tempos de congelamento da solução modelo de polpas de frutas embaladas e acondicionadas em diferentes arranjos de camadas no interior das caixas do empilhamento foram avaliados sob várias condições de operação encontradas nas práticas comerciais. Nestes tipos de processos, as caixas contêm uma porosidade significativa e métodos para avaliar como esta afeta o tempo de congelamento, torna o problema de difícil resolução. Procedimentos para as estimativas dos tempos de congelamento, usando modelos encontrados na literatura, foram comparados com medidas experimentais através da aquisição de dados de tempo/temperatura. Os resultados mostraram que o escoamento do ar entre as embalagens é um parâmetro significativo nas estimativas dos tempos de congelamento. Quando é considerada a presença de canais preferenciais, dependendo do método utilizado, estes valores são subestimados em cerca de 10% quando comparados com os valores experimentais. As isotermas tra

  20. Emergence of cooperation induced by preferential learning

    CERN Document Server

    Ren, J; Wang, W X; Yan, G; Ren, Jie; Wang, Bing-Hong; Wang, Wen-Xu; Yan, Gang

    2006-01-01

    The evolutionary Prisoner's Dilemma Game (PDG) and the Snowdrift Game (SG) with preferential learning mechanism are studied in the Barab\\'asi-Albert network. Simulation results demonstrate that the preferential learning of individuals remarkably promotes the cooperative behavior for both two games over a wide range of payoffs. To understand the effect of preferential learning on the evolution of the systems, we investigate the time series of the cooperator density for different preferential strength and payoffs. It is found that in some specific cases two games both show the $1/f$-scaling behaviors, which indicate the existence of long range correlation. We also figure out that when the large degree nodes have high probability to be selected, the PDG displays a punctuated equilibrium-type behavior. On the contrary, the SG exhibits a sudden increase feature. These temporary instable behaviors are ascribed to the strategy shift of the large degree nodes.

  1. Correlations in Networks associated to Preferential Growth

    OpenAIRE

    Gronlund, Andreas; Sneppen, Kim; Minnhagen, Petter

    2004-01-01

    Combinations of random and preferential growth for both on-growing and stationary networks are studied and a hierarchical topology is observed. Thus for real world scale-free networks which do not exhibit hierarchical features preferential growth is probably not the main ingredient in the growth process. An example of such real world networks includes the protein-protein interaction network in yeast, which exhibits pronounced anti-hierarchical features.

  2. Assessing preferential flow by simultaneously injecting nanoparticle and chemical tracers

    KAUST Repository

    Subramanian, S. K.

    2013-01-01

    The exact manner in which preferential (e.g., much faster than average) flow occurs in the subsurface through small fractures or permeable connected pathways of other kinds is important to many processes but is difficult to determine, because most chemical tracers diffuse quickly enough from small flow channels that they appear to move more uniformly through the rock than they actually do. We show how preferential flow can be assessed by injecting 2 to 5 nm carbon particles (C-Dots) and an inert KBr chemical tracer at different flow rates into a permeable core channel that is surrounded by a less permeable matrix in laboratory apparatus of three different designs. When the KBr tracer has a long enough transit through the system to diffuse into the matrix, but the C-Dot tracer does not, the C-Dot tracer arrives first and the KBr tracer later, and the separation measures the degree of preferential flow. Tracer sequestration in the matrix can be estimated with a Peclet number, and this is useful for experiment design. A model is used to determine the best fitting core and matrix dispersion parameters and refine estimates of the core and matrix porosities. Almost the same parameter values explain all experiments. The methods demonstrated in the laboratory can be applied to field tests. If nanoparticles can be designed that do not stick while flowing through the subsurface, the methods presented here could be used to determine the degree of fracture control in natural environments, and this capability would have very wide ranging value and applicability.

  3. The preferential flow of soil: A widespread phenomenon in pedological perspectives

    Science.gov (United States)

    Zhang, Yinghu; Zhang, Mingxiang; Niu, Jianzhi; Zheng, Haijin

    2016-06-01

    The article provides an overview of studies about the preferential flow phenomenon. This phenomenon is one of the types of the transportation of water solution through the soil profile by preferential channels (pathways) with a relatively high speed and with a slight change in the chemical composition of the solution. Interest in this phenomenon has risen sharply in the last two decades due to the observed fast transportation of contaminants from soil surface into groundwater level. On the basis of the literature data, the authors give the definition of this phenomenon, consider its types, degree, features, mechanisms, methods and models and research perspectives, in particular the interaction between preferential flow and soil matrix flow. The article considers the aspects of the movement of soil water carrying heavy metals and pesticides; hence, it concerns the protection of environment and people's health. It provides the thorough review of the studies on the preferential flow, and describes the research directions and their development.

  4. Mapping preferential flow pathways in a riparian wetland using ground-penetrating radar

    Science.gov (United States)

    Gormally, Kevin Hill

    Preferential flow of water through channels in the soil has been implicated as a vehicle for groundwater and surface water contamination in forested riparian wetland buffers. Water conducted through these by-pass channels can circumvent interaction with wetland biota, biomass, and soils, thereby reducing the buffering capacity of the riparian strips for adsorption and uptake of excess nutrient loads from neighboring agricultural fields and urbanized lands. Models of riparian function need to account for preferential flow to accurately estimate nutrient flux to stream channels, but there are currently no methods for determining the form and prevalence of these pathways outside of extensive destructive sampling. This research developed, tested, and validated a new application of non-invasive ground-penetrating radar technology (GPR) for mapping the three-dimensional structure of near-surface (0-1 m) lateral preferential flow channels. Manual and automated detection methodologies were created for analyzing GPR scan data to locate the channels in the subsurface. The accuracy of the methodologies was assessed in two field test plots with buried PVC pipes simulating the riparian channels. The manual methodology had a 0% Type I error rate and 8% Type II error rate; the automated version had a validated by transmission of tracer dye through the study site and ground truth generated from soil core samples (92% accurate). These GPR tools will enable researchers to efficiently and effectively characterize lateral preferential flow without negatively impacting environmentally sensitive wetland areas. Scientists can now directly study these flow mechanisms to investigate the effects of by-pass pathways on nutrient fate in riparian buffers and the interactions of preferential flow with plant and animal systems.

  5. Effect of urea on biomimetic aggregates

    Directory of Open Access Journals (Sweden)

    F.H. Florenzano

    1997-02-01

    Full Text Available The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolayers was investigated to obtain insights into the effect of the denaturant on structured macromolecules. Direct evidence obtained from light scattering (static and dynamic, monolayer maximum isothermal compression and ionic conductivity measurements, together with indirect evidence from fluorescence photodissociation, fluorescence suppression, and thermal reactions, strongly indicates the direct interaction mechanism of urea with the aggregates. Preferential solvation of the surfactant headgroups by urea results in an increase in the monomer dissociation degree (when applied, which leads to an increase in the area per headgroup and also in the loss of counterion affinities

  6. Effect of urea on biomimetic aggregates.

    Science.gov (United States)

    Florenzano, F H; Politi, M J

    1997-02-01

    The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolayers) was investigated to obtain insights into the effect of the denaturant on structured macromolecules. Direct evidence obtained from light scattering (static and dynamic), monolayer maximum isothermal compression and ionic conductivity measurements, together with indirect evidence from fluorescence photodissociation, fluorescence suppression, and thermal reactions, strongly indicates the direct interaction mechanism of urea with the aggregates. Preferential solvation of the surfactant headgroups by urea results in an increase in the monomer dissociation degree (when applied), which leads to an increase in the area per headgroup and also in the loss of counterion affinities. PMID:9239302

  7. Discovering Preferential Patterns in Sectoral Trade Networks.

    Directory of Open Access Journals (Sweden)

    Isabella Cingolani

    Full Text Available We analyze the patterns of import/export bilateral relations, with the aim of assessing the relevance and shape of "preferentiality" in countries' trade decisions. Preferentiality here is defined as the tendency to concentrate trade on one or few partners. With this purpose, we adopt a systemic approach through the use of the tools of complex network analysis. In particular, we apply a pattern detection approach based on community and pseudocommunity analysis, in order to highlight the groups of countries within which most of members' trade occur. The method is applied to two intra-industry trade networks consisting of 221 countries, relative to the low-tech "Textiles and Textile Articles" and the high-tech "Electronics" sectors for the year 2006, to look at the structure of world trade before the start of the international financial crisis. It turns out that the two networks display some similarities and some differences in preferential trade patterns: they both include few significant communities that define narrow sets of countries trading with each other as preferential destinations markets or supply sources, and they are characterized by the presence of similar hierarchical structures, led by the largest economies. But there are also distinctive features due to the characteristics of the industries examined, in which the organization of production and the destination markets are different. Overall, the extent of preferentiality and partner selection at the sector level confirm the relevance of international trade costs still today, inducing countries to seek the highest efficiency in their trade patterns.

  8. Discovering Preferential Patterns in Sectoral Trade Networks.

    Science.gov (United States)

    Cingolani, Isabella; Piccardi, Carlo; Tajoli, Lucia

    2015-01-01

    We analyze the patterns of import/export bilateral relations, with the aim of assessing the relevance and shape of "preferentiality" in countries' trade decisions. Preferentiality here is defined as the tendency to concentrate trade on one or few partners. With this purpose, we adopt a systemic approach through the use of the tools of complex network analysis. In particular, we apply a pattern detection approach based on community and pseudocommunity analysis, in order to highlight the groups of countries within which most of members' trade occur. The method is applied to two intra-industry trade networks consisting of 221 countries, relative to the low-tech "Textiles and Textile Articles" and the high-tech "Electronics" sectors for the year 2006, to look at the structure of world trade before the start of the international financial crisis. It turns out that the two networks display some similarities and some differences in preferential trade patterns: they both include few significant communities that define narrow sets of countries trading with each other as preferential destinations markets or supply sources, and they are characterized by the presence of similar hierarchical structures, led by the largest economies. But there are also distinctive features due to the characteristics of the industries examined, in which the organization of production and the destination markets are different. Overall, the extent of preferentiality and partner selection at the sector level confirm the relevance of international trade costs still today, inducing countries to seek the highest efficiency in their trade patterns. PMID:26485163

  9. Preferential sampling in veterinary parasitological surveillance

    Directory of Open Access Journals (Sweden)

    Lorenzo Cecconi

    2016-04-01

    Full Text Available In parasitological surveillance of livestock, prevalence surveys are conducted on a sample of farms using several sampling designs. For example, opportunistic surveys or informative sampling designs are very common. Preferential sampling refers to any situation in which the spatial process and the sampling locations are not independent. Most examples of preferential sampling in the spatial statistics literature are in environmental statistics with focus on pollutant monitors, and it has been shown that, if preferential sampling is present and is not accounted for in the statistical modelling and data analysis, statistical inference can be misleading. In this paper, working in the context of veterinary parasitology, we propose and use geostatistical models to predict the continuous and spatially-varying risk of a parasite infection. Specifically, breaking with the common practice in veterinary parasitological surveillance to ignore preferential sampling even though informative or opportunistic samples are very common, we specify a two-stage hierarchical Bayesian model that adjusts for preferential sampling and we apply it to data on Fasciola hepatica infection in sheep farms in Campania region (Southern Italy in the years 2013-2014.

  10. A generalized theory of preferential linking

    Science.gov (United States)

    Hu, Haibo; Guo, Jinli; Liu, Xuan; Wang, Xiaofan

    2014-12-01

    There are diverse mechanisms driving the evolution of social networks. A key open question dealing with understanding their evolution is: How do various preferential linking mechanisms produce networks with different features? In this paper we first empirically study preferential linking phenomena in an evolving online social network, find and validate the linear preference. We propose an analyzable model which captures the real growth process of the network and reveals the underlying mechanism dominating its evolution. Furthermore based on preferential linking we propose a generalized model reproducing the evolution of online social networks, and present unified analytical results describing network characteristics for 27 preference scenarios. We study the mathematical structure of degree distributions and find that within the framework of preferential linking analytical degree distributions can only be the combinations of finite kinds of functions which are related to rational, logarithmic and inverse tangent functions, and extremely complex network structure will emerge even for very simple sublinear preferential linking. This work not only provides a verifiable origin for the emergence of various network characteristics in social networks, but bridges the micro individuals' behaviors and the global organization of social networks.

  11. The European Union preferential trade with developing countries. Total trade restrictiveness and the case of sugar

    OpenAIRE

    Conforti, Piero; Ford, Deep; Hallam, David; Rapsomanikis, George; Salvatici, Luca

    2007-01-01

    Preferential trade agreements are a central issue in the multilateral trade liberalization process. The extent to which such agreements are effective in improving market access for developing and developed countries is important because trade liberalization results in eroding their value to the beneficiary countries, expressed as export revenue. This paper focuses on the estimation of a theoretically founded bilateral aggregated measure of trade restrictiveness, the Mercantilistic Trade Restr...

  12. Reverse preferential spread in complex networks

    Science.gov (United States)

    Toyoizumi, Hiroshi; Tani, Seiichi; Miyoshi, Naoto; Okamoto, Yoshio

    2012-08-01

    Large-degree nodes may have a larger influence on the network, but they can be bottlenecks for spreading information since spreading attempts tend to concentrate on these nodes and become redundant. We discuss that the reverse preferential spread (distributing information inversely proportional to the degree of the receiving node) has an advantage over other spread mechanisms. In large uncorrelated networks, we show that the mean number of nodes that receive information under the reverse preferential spread is an upper bound among any other weight-based spread mechanisms, and this upper bound is indeed a logistic growth independent of the degree distribution.

  13. Assortativity in generalized preferential attachment models

    CERN Document Server

    Krot, Alexander

    2016-01-01

    In this paper, we analyze assortativity of preferential attachment models. We deal with a wide class of preferential attachment models (PA-class). It was previously shown that the degree distribution in all models of the PA-class follows a power law. Also, the global and the average local clustering coefficients were analyzed. We expand these results by analyzing the assortativity property of the PA-class of models. Namely, we analyze the behavior of $d_{nn}(d)$ which is the average degree of a neighbor of a vertex of degree $d$.

  14. Flow Partitioning in Fully Saturated Soil Aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaofan; Richmond, Marshall C.; Scheibe, Timothy D.; Perkins, William A.; Resat, Haluk

    2014-03-30

    Microbes play an important role in facilitating organic matter decomposition in soils, which is a major component of the global carbon cycle. Microbial dynamics are intimately coupled to environmental transport processes, which control access to labile organic matter and other nutrients that are needed for the growth and maintenance of microorganisms. Transport of soluble nutrients in the soil system is arguably most strongly impacted by preferential flow pathways in the soil. Since the physical structure of soils can be characterized as being formed from constituent micro aggregates which contain internal porosity, one pressing question is the partitioning of the flow among the “inter-aggregate” and “intra-aggregate” pores and how this may impact overall solute transport within heterogeneous soil structures. The answer to this question is particularly important in evaluating assumptions to be used in developing upscaled simulations based on highly-resolved mechanistic models. We constructed a number of diverse multi-aggregate structures with different packing ratios by stacking micro-aggregates containing internal pores and varying the size and shape of inter-aggregate pore spacing between them. We then performed pore-scale flow simulations using computational fluid dynamics methods to determine the flow patterns in these aggregate-of-aggregates structures and computed the partitioning of the flow through intra- and inter-aggregate pores as a function of the spacing between the aggregates. The results of these numerical experiments demonstrate that soluble nutrients are largely transported via flows through inter-aggregate pores. Although this result is consistent with intuition, we have also been able to quantify the relative flow capacity of the two domains under various conditions. For example, in our simulations, the flow capacity through the aggregates (intra-aggregate flow) was less than 2% of the total flow when the spacing between the aggregates

  15. The Probabilistic Nature of Preferential Choice

    Science.gov (United States)

    Rieskamp, Jorg

    2008-01-01

    Previous research has developed a variety of theories explaining when and why people's decisions under risk deviate from the standard economic view of expected utility maximization. These theories are limited in their predictive accuracy in that they do not explain the probabilistic nature of preferential choice, that is, why an individual makes…

  16. Satellite observed preferential states in soil moisture

    Science.gov (United States)

    Vilasa, Luis U.; De Jeu, Richard A. M.; Dolman, Han A. J.; Wang, Guojie

    2013-04-01

    This study presents observational evidence for the existence of preferential states in soil moisture content. Recently there has been much debate about the existence, location and explanations for preferential states in soil moisture. A number of studies have provided evidence either in support or against the hypothesis of a positive feedback mechanism between soil moisture and subsequent precipitation in certain regions. Researchers who support the hypothesis that preferential states in soil moisture holds information about land atmosphere feedback base their theory on the impact of soil moisture on the evaporation process. Evaporation recycles moisture to the atmosphere and soil moisture has a direct impact on the supply part of this process but also on the partitioning of the available energy for evaporation. According to this theory, the existence of soil moisture bimodality can be used as an indication of possible land-atmosphere feedbacks, to be compared with model simulations of soil moisture feedbacks. On the other hand, other researchers argue that seasonality in the meteorological conditions in combination with the non-linearity of soil moisture response alone can induce bimodality. In this study we estimate the soil moisture bimodality at a global scale as derived from the recently available 30+ year ESA Climate Change Initative satellite soil moisture dataset. An Expectation-Maximization iterative algorithm is used to find the best Gaussian Mixture Model, pursuing the highest likelihood for soil moisture bimodality. With this approach we mapped the regions where bi-modal probability distribution of soil moisture appears for each month for the period between 1979-2010. These bimodality areas are analyzed and compared to maps of model simulations of soil moisture feedbacks. The areas where more than one preferential state exists compare surprisingly well with the map of land-atmosphere coupling strength from model simulations. This approach might

  17. Preferential attachment in the protein network evolution

    OpenAIRE

    Eisenberg, Eli; Levanon, Erez Y.

    2003-01-01

    The Saccharomyces cerevisiae protein-protein interaction map, as well as many natural and man-made networks, shares the scale-free topology. The preferential attachment model was suggested as a generic network evolution model that yields this universal topology. However, it is not clear that the model assumptions hold for the protein interaction network. Using a cross genome comparison we show that (a) the older a protein, the better connected it is, and (b) The number of interactions a prote...

  18. Network Non-Neutrality through Preferential Signaling

    OpenAIRE

    Hanawal, Manjesh Kumar; Altman, Eitan

    2013-01-01

    One of the central issues in the debate on network neutrality has been whether one should allow or prevent preferential treatment by an internet service provider (ISP) of traffic according to its origin. This raised the question of whether to allow an ISP to have exclusive agreement with a content provider (CP). In this paper we consider discrimination in the opposite direction. We study the impact that a CP can have on the benefits of several competing ISPs by sharing private information con...

  19. Differential survival of solitary and aggregated bacterial cells promotes aggregate formation on leaf surfaces

    Science.gov (United States)

    Monier, J.-M.; Lindow, S. E.

    2003-01-01

    The survival of individual Pseudomonas syringae cells was determined on bean leaf surfaces maintained under humid conditions or periodically exposed to desiccation stress. Cells of P. syringae strain B728a harboring a GFP marker gene were visualized by epifluorescence microscopy, either directly in situ or after recovery from leaves, and dead cells were identified as those that were stained with propidium iodide in such populations. Under moist, conducive conditions on plants, the proportion of total live cells was always high, irrespective of their aggregated state. In contrast, the proportion of the total cells that remained alive on leaves that were periodically exposed to desiccation stress decreased through time and was only ≈15% after 5 days. However, the fraction of cells in large aggregates that were alive on such plants in both condition was much higher than more solitary cells. Immediately after inoculation, cells were randomly distributed over the leaf surface and no aggregates were observed. However, a very aggregated pattern of colonization was apparent within 7 days, and >90% of the living cells were located in aggregates of 100 cells or more. Our results strongly suggest that, although conducive conditions favor aggregate formation, such cells are much more capable of tolerating environmental stresses, and the preferential survival of cells in aggregates promotes a highly clustered spatial distribution of bacteria on leaf surfaces. PMID:14665692

  20. Acetone:isomedzation and aggregation

    Institute of Scientific and Technical Information of China (English)

    HU Zhan; JIN Ming-xing; XU Xue-song; CHENG Xi-hui; DING Da-jun

    2006-01-01

    The advanced experimental and theoretical techniques enable us to obtain information on the rearrangement of atoms or molecules in a reaction nowadays.As an example,we report on our research work on acetone isomerization and aggregation to give an insight into the reaction pathways,the products and their structures,and the growth regularity of aggregation.The evidences on the structural change of acetone and the stability of acetone clusters are found by a laser ionization mass spectrometer and the results are interpreted from theoretical analysis based on the DFT/B3LYP method.Various isomerization channels of acetone have been established and the optimal structures of the neutral clusters (CH3COCH3)n and the protonated acetone clusters (CH3COCHa)n H+ for n=1-7 have been determined.

  1. Using the dye tracer for visualization of preferential flow in macro and micro-scale

    Science.gov (United States)

    Kodesova, Radka; Nemecek, Karel; Kodes, Vit; Fer, Miroslav; Jirku, Veronika; Nikodem, Antonin; Zigova, Anna; Jaksik, Ondrej; Kocarek, Martin

    2010-05-01

    Study is focused on the visualization of the preferential flow in different soil types and their horizons using the dye tracer experiment. Study was performed in the Haplic Luvisol in Hněvčeves and the Haplic Cambisol in Humpolec in the Czech Republic. The 100 (Haplic Luvisol) and 50 (Haplic Cambisol) liters of solute of dye Brilliant Blue FCF (5g/litr) was infiltrated on a 1 x 1 m plot (applying an initial ponding depth of 10 and 5 cm, respectively) immediately after the wheat harvest. On the next day, one half of the plot was sliced horizontally and another half vertically to study the dye distribution within the soil profile to the depth of 100 cm (macro-scale). The 3-D image of the dye distribution was created. In addition, the thin soil sections were made and micromorphological images were used to study a soil aggregate structure and dye distribution in micro-scale. The staining patterns within the vertical and horizontal sections documented very different nature of the preferential flow in different soil types and also within the soil profiles. Images of the Haplic Luvisol showed that while dye tracer was partly regularly transported and only some isolated domains were visible in the surface Ap1 horizon, the preferential flow occurred in the subsurface horizons. The preferential flow in the upper subsurface Ap2 horizon (plow pan) was caused by the gravitational biopores in the very compact matrix structure, which considerably slowed down the dye transport. In the case of deeper horizons (Bt1 and Bt2), the preferential flow occurred due to the gravitational biopores and extensively developed prismatic structure (small and very large aggregates in the Bt1 and Bt2 horizon respectively), which was highly affected by clay coatings. Even better characterization of the preferential flow particularly in these two horizons was obtained, when the same ponding dye infiltration experiment was performed directly on the top of the Bt1 horizon. Images of the Haplic

  2. Aggregating Reputation Feedback

    OpenAIRE

    Garcin, Florent; Faltings, Boi; Jurca, Radu

    2009-01-01

    A fundamental task in reputation systems is to aggregate multiple feedback ratings into a single value that can be used to compare the reputation of different entities. Feedback is most commonly aggregated using the arithmetic mean. However, the mean is quite susceptible to outliers and biases, and thus may not be the most informative aggregate of the reports. We consider three criteria to assess the quality of an aggregator: the informativness, the robustness and the strategyproofness, and a...

  3. Preferential sampling of helicity by isotropic helicoids

    CERN Document Server

    Gustavsson, Kristian

    2016-01-01

    We present a theoretical and numerical study on the motion of isotropic helicoids in complex flows. These are particles whose motion is invariant under rotations but not under mirror reflections of the particle. This is the simplest, yet unexplored, extension of the much studied case of small spherical particles. We show that heavy isotropic helicoids, due to the coupling between translational and rotational degrees of freedom, preferentially sample different helical regions in laminar or chaotic advecting flows. This opens the way to control and engineer particles able to track complex flow structures with potential applications to microfluidics and turbulence.

  4. NADIM-Travel: A Multiagent Platform for Travel Services Aggregation

    OpenAIRE

    Ben Ameur, Houssein; Bédard, François; Vaucher, Stéphane; Kropf, Peter; Chaib-draaa, Brahim; Gérin-Lajoie, Robert

    2010-01-01

    With the Internet as a growing channel for travel services distribution, sophisticated travel services aggregators are increasingly in demand. A travel services aggregation platform should be able to manage the heterogeneous characteristics of the many existing travel services. It should also be as scalable, robust, and flexible as possible. Using multiagent technology, we designed and implemented a multiagent platform for travel services aggregation called NADIM-Travel. In this platform, a p...

  5. Growth fluctuation in preferential attachment dynamics

    Science.gov (United States)

    Hashimoto, Yasuhiro

    2016-04-01

    In the Yule-Simon process, creation and selection of words follows the preferential attachment mechanism, resulting in a power-law growth in the cumulative number of individual word occurrences as well as the power-law population distribution of the vocabulary. This is derived using mean-field approximation, assuming a continuum limit of both the time and number of word occurrences. However, time and word occurrences are inherently discrete in the process, and it is natural to assume that the cumulative number of word occurrences has a certain fluctuation around the average behavior predicted by the mean-field approximation. We derive the exact and approximate forms of the probability distribution of such fluctuation analytically, and confirm that those probability distributions are well supported by the numerical experiments.

  6. Green frame aggregation scheme for Wi-Fi networks

    KAUST Repository

    Alaslani, Maha S.

    2015-07-01

    Frame aggregation is a major enhancement in the IEEE 802.11 family to boost the network performance. The increasing awareness about energy efficiency motivates the re-think of frame aggregation design. In this paper, we propose a novel Green Frame Aggregation (GFA) scheduling scheme that optimizes the aggregate size based on channel quality in order to minimize the consumed energy. GFA selects an optimal sub-frame size that satisfies the loss constraint for real-time applications as well as the energy budget of the ideal channel. This scheme is implemented and evaluated using a testbed deployment. The experimental analysis shows that GFA outperforms the conventional frame aggregation methodology in terms of energy efficiency by about 6x in the presence of severe interference conditions. Moreover, GFA outperforms the static frame sizing method in terms of network goodput while maintaining the same end-to-end latency.

  7. Diffusion in aggregated soil.

    OpenAIRE

    Rappoldt, C.

    1992-01-01

    The structure of an aggregated soil is characterized by the distribution of the distance from an arbitrary point in the soil to the nearest macropore or crack. From this distribution an equivalent model system is derived to which a diffusion model can be more easily applied. The model system consists of spherical, or cylindrical or plane aggregates, which do not represent the individual aggregates of the soil, however. The radii of the spheres, cylinders or plane sheets represent different le...

  8. Provenance for Aggregate Queries

    OpenAIRE

    Yael Amsterdamer; Daniel Deutch; Val Tannen

    2011-01-01

    We study in this paper provenance information for queries with aggregation. Provenance information was studied in the context of various query languages that do not allow for aggregation, and recent work has suggested to capture provenance by annotating the different database tuples with elements of a commutative semiring and propagating the annotations through query evaluation. We show that aggregate queries pose novel challenges rendering this approach inapplicable. Consequently, we propose...

  9. Average Shape of Transport-Limited Aggregates

    Science.gov (United States)

    Davidovitch, Benny; Choi, Jaehyuk; Bazant, Martin Z.

    2005-08-01

    We study the relation between stochastic and continuous transport-limited growth models. We derive a nonlinear integro-differential equation for the average shape of stochastic aggregates, whose mean-field approximation is the corresponding continuous equation. Focusing on the advection-diffusion-limited aggregation (ADLA) model, we show that the average shape of the stochastic growth is similar, but not identical, to the corresponding continuous dynamics. Similar results should apply to DLA, thus explaining the known discrepancies between average DLA shapes and viscous fingers in a channel geometry.

  10. The Aggregate-Supply/Aggregate-Demand Model

    OpenAIRE

    BARRO, Robert J.

    1994-01-01

    The aggregate-supply/ aggregate-demand (AS-AD) model is popular in textbooks, but has problems with logical consistency. In one interpretation, the Keynesian underpinnings of the AD curve-derived from the IS/LM model with downward price stickiness-conflict with the determination of the price level at the intersection of the AS and AD curves. In another view, the model corresponds to rational-expectations theories in which Keynesian properties are absent. In a third interpretation, the model i...

  11. Transport implications resulting from internal redistribution of arsenic and iron within constructed soil aggregates.

    Science.gov (United States)

    Masue-Slowey, Yoko; Kocar, Benjamin D; Jofré, Sergio Andrés Bea; Mayer, K Ulrich; Fendorf, Scott

    2011-01-15

    Soils are an aggregate-based structured media that have a multitude of pore domains resulting in varying degrees of advective and diffusive solute and gas transport. Consequently, a spectrum of biogeochemical processes may function at the aggregate scale that collectively, and coupled with solute transport, determine element cycling in soils and sediments. To explore how the physical structure impacts biogeochemical processes influencing the fate and transport of As, we examined temporal changes in speciation and distribution of As and Fe within constructed aggregates through experimental measurement and reactive transport simulations. Spherical aggregates were made with As(V)-bearing ferrihydrite-coated sand inoculated with Shewanella sp. ANA-3; aerated solute flow around the aggregate was then induced. Despite the aerated aggregate exterior, where As(V) and ferrihydrite persist as the dominant species, anoxia develops within the aggregate interior. As a result, As and Fe redox gradients emerge, and the proportion of As(III) and magnetite increases toward the aggregate interior. Arsenic(III) and Fe(II) produced in the interior migrate toward the aggregated exterior and result in coaccumulation of As and Fe(III) proximal to preferential flow paths as a consequence of oxygenic precipitation. The oxidized rind of aggregates thus serves as a barrier to As release into advecting pore-water, but also leads to be a buildup of this hazardous element at preferential flow boundaries that could be released upon shifting geochemical conditions. PMID:21158450

  12. Oxygen influx and geochemistry of percolate water from reactive mine waste rock underlying a sloping channelled soil cover

    Energy Technology Data Exchange (ETDEWEB)

    Song Qing, E-mail: qsong3@uwo.ca [Geotechnical Research Center, Department of Civil and Environmental Engineering, University of Western Ontario, 1151 Richmond Street, London, ON, N6A 5B9 (Canada); Yanful, Ernest K., E-mail: eyanful@eng.uwo.ca [Geotechnical Research Center, Department of Civil and Environmental Engineering, University of Western Ontario, 1151 Richmond Street, London, ON, N6A 5B9 (Canada)

    2011-05-15

    Research Highlights: > A channelled cover with preferential flow can still mitigate ARD to some extent. > Oxygen ingress was more sensitive to the location of the channel than to K{sub s}. > The channel in the barrier layer was a major passage for O{sub 2} ingress. > Actual flushing was an important factor when estimating O{sub 2} decay coefficient. - Abstract: An ideal engineered soil cover can mitigate acid rock drainage (ARD) by limiting water and gaseous O{sub 2} ingress into an underlying waste rock pile. However, the barrier layer in the soil cover almost invariably tends to develop cracks or fractures after placement. These cracks may change water flow and O{sub 2} transport in the soil cover and decrease performance in the long run. The present study employed a 10-cm-wide sand-filled channel installed in a soil barrier layer (silty clay) to model the aggregate of cracks or fractures that may be present in the cover. The soil cover had a slope of 20%. Oxygen transport through the soil cover and oxidation of the underlying waste rock were investigated and compared to a controlled column test with bare waste rock (without soil cover). Moreover, gaseous O{sub 2} transport in the soil cover with channel and its sensitivity to channel location as well as the influence of the saturated hydraulic conductivity of the channel material were modeled using the commercial software VADOSE/W. The results indicted that the waste rock underlying the soil cover with channel had a lower oxidation rate than the waste rock without cover because of reduced O{sub 2} ingress and water flushing in the soil cover with channel, which meant a partial soil cover might still be effective to some extent in reducing ARD generation. Gaseous O{sub 2} ingress into the covered waste rock was more sensitive to the channel location than to the saturated hydraulic conductivity of the material filling the channel. Aqueous equilibrium speciation modeling and scanning electron microscopy with energy

  13. Amorphous Aggregation of Amyloid Beta 1-40 Peptide in Confined Space.

    Science.gov (United States)

    Foschi, Giulia; Albonetti, Cristiano; Liscio, Fabiola; Milita, Silvia; Greco, Pierpaolo; Biscarini, Fabio

    2015-11-16

    The amorphous aggregation of Aβ1-40 peptide is addressed by using micromolding in capillaries. Both the morphology and the size of the aggregates are modulated by changing the contact angle of the sub-micrometric channel walls. Upon decreasing the hydrophilicity of the channels, the aggregates change their morphology from small aligned drops to discontinuous lines, thereby keeping their amorphous structure. Aβ1-40 fibrils are observed at high contact angles.

  14. Modeling online social networks based on preferential linking

    Institute of Scientific and Technical Information of China (English)

    Hu Hai-Bo; Guo Jin-Li; Chen Jun

    2012-01-01

    We study the phenomena of preferential linking in a large-scale evolving online social network and find that the linear preference holds for preferential creation,preferential acceptance,and preferential attachment.Based on the linear preference,we propose an analyzable model,which illustrates the mechanism of network growth and reproduces the process of network evolution.Our simulations demonstrate that the degree distribution of the network produced by the model is in good agreement with that of the real network.This work provides a possible bridge between the micro-mechanisms of network growth and the macrostructures of online social networks.

  15. Modeling online social networks based on preferential linking

    International Nuclear Information System (INIS)

    We study the phenomena of preferential linking in a large-scale evolving online social network and find that the linear preference holds for preferential creation, preferential acceptance, and preferential attachment. Based on the linear preference, we propose an analyzable model, which illustrates the mechanism of network growth and reproduces the process of network evolution. Our simulations demonstrate that the degree distribution of the network produced by the model is in good agreement with that of the real network. This work provides a possible bridge between the micro-mechanisms of network growth and the macrostructures of online social networks

  16. Comparing Two Different Methods of Preferential Flow Simulation, Using Calibration Constrained Monte Carlo Uncertainty analysis

    Science.gov (United States)

    Schirmer, M.; Ghasemizade, M.; Radny, D.

    2014-12-01

    Many different methods and approaches have been suggested for simulation of preferential flows. However, most of these methods have been tested in lab scales where boundary conditions and material properties are known and under control. The focus of this study is to compare two different approaches for simulating preferential flows in a weighing lysimeter where the scale of simulation is closer to field scales than simulations done in labs. To do so, we applied dual permeability and spatially distributed heterogeneity as two competitive approaches for simulating slow and rapid flow out of a lysimeter. While the dual permeability approach assumes that there is a structure among soil aggregates and that can be captured as a fraction of the porosity, the other method attributes the existence of preferential flows to heterogeneity distributed within the domain. The two aforementioned approaches were used in order to simulate daily recharge values of a lysimeter. The analysis included a calibration phase, which started from March 2012 until March 2013, and a validation phase which lasted a year following the calibration period. The simulations were performed based on the numerical and 3-D physically based model HydroGeoSphere. The nonlinear uncertainty analysis of the results indicate that they are comparable.

  17. [Macropore characteristics and its relationships with the preferential flow in broadleaved forest soils of Simian Mountains].

    Science.gov (United States)

    Wang, Wei; Zhang, Hong-jiang; Cheng, Jin-hua; Wu, Yu-he; Du, Shi-cai; Wang, Ran

    2010-05-01

    Brilliant blue dyeing and water breakthrough curve were applied to study the number and distribution of macropores and their relations to the preferential flow in typical sub-tropic broad-leaved forest soils of Simian Mountains. The radii of the macropores were mainly between 0. 3 and 3.0 mm, with the macroporosities in the range of 6.3% to 10.5%, and the macropores were always distributed in aggregation with increasing soil depth. The number of the macropores in each radius interval of dye-stained areas was tenfold increase than that of blank areas. The number of the macropores with radius larger than 0.3 mm, especially larger than 1.5 mm, was the most important factor affecting the occurrence of preferential flow. Significant correlations were found between the number of macropores and the water steady effluent volume, with the highest correlation coefficients of 0.842 and 0.879 for the radii intervals of 0.7-1.5 mm and 1.5-3.0 mm, respectively. Macro-pore continuity in dye-stained areas was better than that in blank areas, especially in the radius interval of 1.5-3.0 mm, with the biggest difference of 78.31%. In dye-stained areas, the number of macropores decreased gradually with soil depth. The filler-like distribution of macropores formed an effective water pressure gradient, which resulted in the preferential transport of water. PMID:20707104

  18. Aggregates from mineral wastes

    Directory of Open Access Journals (Sweden)

    Baic Ireneusz

    2016-01-01

    Full Text Available The problem concerning the growing demand for natural aggregates and the need to limit costs, including transportation from remote deposits, cause the increase in growth of interest in aggregates from mineral wastes as well as in technologies of their production and recovery. The paper presents the issue related to the group of aggregates other than natural. A common name is proposed for such material: “alternative aggregates”. The name seems to be fully justified due to adequacy of this term because of this raw materials origin and role, in comparison to the meaning of natural aggregates based on gravel and sand as well as crushed stones. The paper presents characteristics of the market and basic application of aggregates produced from mineral wastes, generated in the mining, power and metallurgical industries as well as material from demolished objects.

  19. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten;

    2013-01-01

    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...... by tissue factor evaluated by means of impedance aggregometry. Citrated whole blood from healthy volunteers and haemophilia A patients with the addition of inhibitors of the contact pathway and fibrin polymerization was evaluated. In healthy persons, a second wave of platelet aggregation was found...

  20. Preferential Regulatory Treatment and Banks' Demand for Government Bonds

    NARCIS (Netherlands)

    Bonner, Clemens

    2015-01-01

    The purpose of this paper is to analyze the impact of preferential regulatory treatment on banks’ demand for government bonds. Using unique transaction-level data, our analysis suggests that preferential treatment in microprudential liquidity and capital regulation significantly increases banks’ dem

  1. Preferential Option for the Poor: Making a Pedagogical Choice

    Science.gov (United States)

    Kirylo, James D.

    2006-01-01

    When children are sick, hurt, or in desperate need, parents/caregivers naturally make preferential options for them. Yet, as it relates to social justice, particularly when working with students from marginalized and poverty situations, the concept of making a preferential option in a school setting is not as clear. However, a school setting is a…

  2. Aggregated Computational Toxicology Online Resource

    Data.gov (United States)

    U.S. Environmental Protection Agency — Aggregated Computational Toxicology Online Resource (AcTOR) is EPA's online aggregator of all the public sources of chemical toxicity data. ACToR aggregates data...

  3. Soil properties and preferential solute transport at the field scale

    DEFF Research Database (Denmark)

    Koestel, J K; Minh, Luong Nhat; Nørgaard, Trine;

    management practices (e.g. Beven, K., 1991, modeling preferential flow - an uncertain future, Preferential Flow, 1-11). In our study, we present evidence that disproves this notion. We evaluated breakthrough curve experiments under a constant irrigation rate of 1 cm/h conducted on 65 soil columns (20 cm......An important fraction of water flow and solute transport through soil takes place through preferential flow paths. Although this had been already observed in the nineteenth century, it had been forgotten by the scientific community until it was rediscovered during the 1970s. The awareness...... of the relevance of preferential flow was broadly re-established in the community by the early 1990s. However, since then, the notion remains widespread among soil scientists that the occurrence and strength of preferential flow cannot be predicted from measurable proxy variables such as soil properties or land...

  4. Recycled aggregates concrete: aggregate and mix properties

    Directory of Open Access Journals (Sweden)

    González-Fonteboa, B.

    2005-09-01

    Full Text Available This study of structural concrete made with recycled concrete aggregate focuses on two issues: 1. The characterization of such aggregate on the Spanish market. This involved conducting standard tests to determine density, water absorption, grading, shape, flakiness and hardness. The results obtained show that, despite the considerable differences with respect to density and water absorption between these and natural aggregates, on the whole recycled aggregate is apt for use in concrete production. 2. Testing to determine the values of basic concrete properties: mix design parameters were established for structural concrete in non-aggressive environments. These parameters were used to produce conventional concrete, and then adjusted to manufacture recycled concrete aggregate (RCA concrete, in which 50% of the coarse aggregate was replaced by the recycled material. Tests were conducted to determine the physical (density of the fresh and hardened material, water absorption and mechanical (compressive strength, splitting tensile strength and modulus of elasticity properties. The results showed that, from the standpoint of its physical and mechanical properties, concrete in which RCA accounted for 50% of the coarse aggregate compared favourably to conventional concrete.

    Se aborda el estudio de hormigones estructurales fabricados con áridos reciclados procedentes de hormigón, incidiéndose en dos aspectos: 1. Caracterización de tales áridos, procedentes del mercado español. Para ello se llevan a cabo ensayos de densidad, absorción, granulometría, coeficiente de forma, índice de lajas y dureza. Los resultados obtenidos han puesto de manifiesto que, a pesar de que existen diferencias notables (sobre todo en cuanto a densidad y absorción con los áridos naturales, las características de los áridos hacen posible la fabricación de hormigones. 2. Ensayos sobre propiedades básicas de los hormigones: se establecen parámetros de dosificaci

  5. Protein Colloidal Aggregation Project

    Science.gov (United States)

    Oliva-Buisson, Yvette J. (Compiler)

    2014-01-01

    To investigate the pathways and kinetics of protein aggregation to allow accurate predictive modeling of the process and evaluation of potential inhibitors to prevalent diseases including cataract formation, chronic traumatic encephalopathy, Alzheimer's Disease, Parkinson's Disease and others.

  6. Preferentially Cytotoxic Constituents of Andrographis paniculata and their Preferential Cytotoxicity against Human Pancreatic Cancer Cell Lines.

    Science.gov (United States)

    Lee, Sullim; Morita, Hiroyuki; Tezuka, Yasuhiro

    2015-07-01

    In the course of our search for anticancer agents based on a novel anti-austerity strategy, we found that the 70% EtOH extract of the crude drug Andrographis Herba (aerial parts of Andrographis paniculata), used in Japanese Kampo medicines, killed PANC-1 human pancreatic cancer cells preferentially in nutrient-deprived medium (NDM). Phytochemical investigation of the 70% EtOH extract led to the isolation of 21 known compounds consisting of six labdane-type diterpenes (11, 15, 17-19, 21), six flavones (5, 7, 10, 12, 14, 20), three flavanones (2, 6, 16), two sterols (3, 8), a fatty acid (1), a phthalate (4), a triterpene (9), and a monoterpene (13). Among them, 14-deoxy-11,12-didehydroandrographolide (17) displayed the most potent preferential cytotoxicity against PANC-1 and PSN-1 cells with PC50 values of 10.0 μM and 9.27 μM, respectively. Microscopical observation, double staining with ethidium bromide (EB) and acridine orange (AO), and flow cytometry with propidium iodide/annexin V double staining indicated that 14-deoxy-11,12-didehydroandrographolide (17) triggered apoptosis-like cell death in NDM with an amino acids and/or serum-sensitive mode. PMID:26410998

  7. Cell aggregation and sedimentation.

    Science.gov (United States)

    Davis, R H

    1995-01-01

    The aggregation of cells into clumps or flocs has been exploited for decades in such applications as biological wastewater treatment, beer brewing, antibiotic fermentation, and enhanced sedimentation to aid in cell recovery or retention. More recent research has included the use of cell aggregation and sedimentation to selectively separate subpopulations of cells. Potential biotechnological applications include overcoming contamination, maintaining plasmid-bearing cells in continuous fermentors, and selectively removing nonviable hybridoma cells from perfusion cultures.

  8. Organic carbon, water repellency and soil stability to slaking at aggregate and intra-aggregate scales

    Science.gov (United States)

    Jordán López, Antonio; García-Moreno, Jorge; Gordillo-Rivero, Ángel J.; Zavala, Lorena M.; Cerdà, Artemi; Alanís, Nancy; Jiménez-Compán, Elizabeth

    2015-04-01

    Water repellency (WR) is a property of some soils that inhibits or delays water infiltration between a few seconds and days or weeks. Inhibited or delayed infiltration contributes to ponding and increases runoff flow generation, often increasing soil erosion risk. In water-repellent soils, water infiltrates preferentially through cracks or macropores, causing irregular soil wetting patterns, the development of preferential flow paths and accelerated leaching of nutrients. Although low inputs of hydrophobic organic substances and high mineralization rates lead to low degrees of WR in cropped soils, it has been reported that conservative agricultural practices may induce soil WR. Although there are many studies at catchment, slope or plot scales very few studies have been carried out at particle or aggregate scale. Intra-aggregate heterogeneity of physical, biological and chemical properties conditions the transport of substances, microbial activity and biochemical processes, including changes in the amount, distribution and chemical properties of organic matter. Some authors have reported positive relationships between soil WR and aggregate stability, since it may delay the entry of water into aggregates, increase structural stability and contribute to reduce soil erosion risk. Organic C (OC) content, aggregate stability and WR are therefore strongly related parameters. In the case of agricultural soils, where both the type of management as crops can influence all these parameters, it is important to evaluate the interactions among them and their consequences. Studies focused on the intra-aggregate distribution of OC and WR are necessary to shed light on the soil processes at a detailed scale. It is extremely important to understand how the spatial distribution of OC in soil aggregates can protect against rapid water entry and help stabilize larger structural units or lead to preferential flow. The objectives of this research are to study [i] the OC content and the

  9. Phosphorus Speciation and Sorption Processes in Preferential flow paths and Soil Matrix in Forested Podzolic Till Soil

    Science.gov (United States)

    Saastamoinen, S.; Laine-Kaulio, H.; Klöve, B.

    2009-04-01

    The importance of preferential flow paths in nutrient leaching and subsurface transport has been identified in several studies mainly on agricultural soils. In forest soils research, decayed root channels, stone surfaces and other secondary soil structures have shown to affect unsaturated flow in glacial till soil. Until recently, the focus has been on nitrogen and carbon dynamics in the preferential flow paths. Preferential flow may also have a fundamental role in phosphorus (P) sorption processes and transport from forested till soils to surface waters. The main objectives of this study were to determine how preferential flow paths affect to P speciation, sorption and leaching in forested podzolic till soil. Field experiments were conducted in mixed coniferous forest, with soil type of glacial sandy till classified as Haplic Podzol. The first experiment was conducted in Ranua, Northern Finland. The preferential flow paths were identified by introducing Acid Blue 9 dye tracer to a 1 m2 study plot. The soil profile was vertically sliced and samples were collected from the stained preferential flow paths and unstained soil matrix. Ammonium-oxalate extracted trace elements and P, total and inorganic P, inorganic P fractions and organic P forms (31P-NMR spectroscopy) were analyzed from the samples. In the second experiment in Sotkamo, Eastern Finland, three 1 m2 study plots were selected from a forested hillslope: top, middle and bottom slope. The detection of preferential flow paths and the sampling procedure was identical to the first plot experiment. Samples were analyzed for ammonium-oxalate extracted trace elements and P. Also, the effect of reaction time, P concentration and temperature on the sorption process in preferential flow paths and soil matrix was studied by kinetic batch-type sorption experiments. Stone surfaces were the most dominant preferential flow paths and contained lower oxalate-extracted and total P concentrations than the soil matrix in all

  10. RFI channels

    Science.gov (United States)

    Mceliece, R. J.

    1980-01-01

    A class of channel models is presented which exhibit varying burst error severity much like channels encountered in practice. An information-theoretic analysis of these channel models is made, and conclusions are drawn that may aid in the design of coded communication systems for realistic noisy channels.

  11. Soil properties and preferential solute transport at the field scale

    Science.gov (United States)

    Koestel, J. K.; Luong, N. M.; Nørgaard, T.; Vendelboe, A. L.; Moldrup, P.; Jarvis, N. J.; Lamandé, M.; Iversen, B. V.; Wollesen de Jonge, L.

    2012-04-01

    An important fraction of water flow and solute transport through soil takes place through preferential flow paths. Although this had been already observed in the nineteenth century, it had been forgotten by the scientific community until it was rediscovered during the 1970s. The awareness of the relevance of preferential flow was broadly re-established in the community by the early 1990s. However, since then, the notion remains widespread among soil scientists that the occurrence and strength of preferential flow cannot be predicted from measurable proxy variables such as soil properties or land management practices (e.g. Beven, K., 1991, Modeling preferential flow - an uncertain future, Preferential Flow, 1-11). In our study, we present evidence that disproves this notion. We evaluated breakthrough curve experiments under a constant irrigation rate of 1 cm/h conducted on 65 soil columns (20 cm diameter and 20 height) which had been sampled from an approximately 1 ha large loamy field-site in Silstrup, Denmark. We show that the holdback factor, which is an indicator for the strength of preferential transport, is strongly correlated to the bulk density, which in turn is correlated to the organic matter content. By applying multiple linear regression in a bootstrapping framework, we could estimate the holdback factor from the bulk density and the very fine sand fraction with a coefficient of determination of 0.65. Our results raise hopes that it is indeed possible to establish pedotransfer functions for soil susceptibility to preferential flow and transport.

  12. Preferential Interactions and the Effect of Protein PEGylation.

    Directory of Open Access Journals (Sweden)

    Louise Stenstrup Holm

    Full Text Available PEGylation is a strategy used by the pharmaceutical industry to prolong systemic circulation of protein drugs, whereas formulation excipients are used for stabilization of proteins during storage. Here we investigate the role of PEGylation in protein stabilization by formulation excipients that preferentially interact with the protein.The model protein hen egg white lysozyme was doubly PEGylated on two lysines with 5 kDa linear PEGs (mPEG-succinimidyl valerate, MW 5000 and studied in the absence and presence of preferentially excluded sucrose and preferentially bound guanine hydrochloride. Structural characterization by far- and near-UV circular dichroism spectroscopy was supplemented by investigation of protein thermal stability with the use of differential scanning calorimetry, far and near-UV circular dichroism and fluorescence spectroscopy. It was found that PEGylated lysozyme was stabilized by the preferentially excluded excipient and destabilized by the preferentially bound excipient in a similar manner as lysozyme. However, compared to lysozyme in all cases the melting transition was lower by up to a few degrees and the calorimetric melting enthalpy was decreased to half the value for PEGylated lysozyme. The ratio between calorimetric and van't Hoff enthalpy suggests that our PEGylated lysozyme is a dimer.The PEGylated model protein displayed similar stability responses to the addition of preferentially active excipients. This suggests that formulation principles using preferentially interacting excipients are similar for PEGylated and non-PEGylated proteins.

  13. Effects of fine root length density and root biomass on soil preferential flow in forest ecosystems

    Directory of Open Access Journals (Sweden)

    Yinghu Zhang

    2015-04-01

    Full Text Available Aim of study: The study was conducted to characterize the impacts of plant roots systems (e.g., root length density and root biomass on soil preferential flow in forest ecosystems. Area of study: The study was carried out in Jiufeng National Forest Park, Beijing, China. Material and methods: The flow patterns were measured by field dye tracing experiments. Different species (Sophora japonica Linn,Platycladus orientalis Franco, Quercus dentata Thunbwere quantified in two replicates, and 12 soil depth were applied. Plant roots were sampled in the sieving methods. Root length density and root biomass were measured by WinRHIZO. Dye coverage was implied in the image analysis, and maximum depth of dye infiltration by direct measurement. Main results: Root length density and root biomass decreased with the increasing distance from soil surface, and root length density was 81.6% higher in preferential pathways than in soil matrix, and 66.7% for root biomass with respect to all experimental plots. Plant roots were densely distributed in the upper soil layers. Dye coverage was almost 100% in the upper 5-10 cm, but then decreased rapidly with soil depth. Root length density and root biomass were different from species: Platycladus orientalis Franco > Quercus dentata Thunb > Sophora japonica Linn. Research highlights: The results indicated that fine roots systems had strong effects on soil preferential flow, particularly root channels enhancing nutrition transport across soil profiles in forest dynamics.

  14. Numerical Simulation of Preferential Flow of Contaminants in Soil

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A simple modeling approach was suggested to simulate preferential transport of water and contaminants in soil.After saturated hydraulic conductivity was interpolated by means of Krige interpolation method or scaling method, and then zoned,the locations where saturated hydraulic conductivity was larger represented regions where preferential flow occurred,because heterogeneity of soil,one of the mechanisms resulting in preferential flow,could be reflected through the difference in saturated hydraulic conductivity.The modeling approach was validated through numerical simulation of contaminant transport in a two-dimensional hypothetical soil profile.The results of the numerical simulation showed that the approach suggested in this study was feasible.

  15. Preferential Market Access, Foreign Aid and Economic Development

    DEFF Research Database (Denmark)

    Afesorgbor, Sylvanus Kwaku; Abreha, Kaleb Girma

    contributed to the economic development of the beneficiary countries. Focusing on the ACP countries over the period 1970-2009, we show that only the EU preferential scheme is effective in promoting exports and that market access plays a significant and economically large role in the development of beneficiary......Several studies highlight that exporters in developing countries face substantial trade costs. To reduce these costs, a few developed countries mainly Canada, the EU, Japan and the USA granted preferential market access to these exporters. We assess whether these preferential accesses have...

  16. Nanocavity Shrinkage and Preferential Amorphization during Irradiation in Silicon

    Institute of Scientific and Technical Information of China (English)

    ZHU Xian-Fang; WANG Zhan-Guo

    2005-01-01

    @@ We model the recent experimental results and demonstrate that the internal shrinkage of nanocavities in silicon is intrinsically associated with preferential amorphization as induced by self-ion irradiation.

  17. Characteristics of Preferentially Attached Network Grown from Small World

    CERN Document Server

    Lee, Seungyoung

    2015-01-01

    We introduce a model for a preferentially attached network which has grown from a small world network. Here, the average path length and the clustering coefficient are estimated, and the topological properties of modeled networks are compared as the initial conditions are changed. As a result, it is shown that the topological properties of the initial network remain even after the network growth. However, the vulnerability of each to preferentially attached nodes being added is not the same. It is found that the average path length rapidly decreases as the ratio of preferentially attached nodes increases and that the characteristics of the initial network can be easily disappeared. On the other hand, the clustering coefficient of the initial network slowly decreases with the ratio of preferentially attached nodes and its clustering characteristic remains much longer.

  18. Sustainable Concrete with Recycled Aggregate

    OpenAIRE

    Kara, P

    2012-01-01

    Concretes produced with recycled aggregates are the subject of several papers recently published in the technical literature. Substitution of natural aggregates can be one of possibilities to take care of landfills and increase of CO2 emissions into the atmosphere in Latvia. Recycled aggregate is a valuable resource; value-added consumption of recycled aggregate, as replacement for virgin aggregate in concrete, can yield significant energy and environmental benefits. In present study recycled...

  19. Its preferential interactions with biopolymers account for diverse observed effects of trehalose.

    Science.gov (United States)

    Hong, Jiang; Gierasch, Lila M; Liu, Zhicheng

    2015-07-01

    Biopolymer homeostasis underlies the health of organisms, and protective osmolytes have emerged as one strategy used by Nature to preserve biopolymer homeostasis. However, a great deal remains unknown about the mechanism of action of osmolytes. Trehalose, as a prominent example, stabilizes proteins against denaturation by extreme temperature and denaturants, preserves membrane integrity upon freezing or in dry conditions, inhibits polyQ-mediated protein aggregation, and suppresses the aggregation of denatured proteins. The underlying thermodynamic mechanisms of such diverse effects of trehalose remain unclear or controversial. In this study, we applied the surface-additive method developed in the Record laboratory to attack this issue. We characterized the key features of trehalose-biopolymer preferential interactions and found that trehalose has strong unfavorable interactions with aliphatic carbon and significant favorable interactions with amide/anionic oxygen. This dissection has allowed us to elucidate the diverse effects of trehalose and to identify the crucial functional group(s) responsible for its effects. With (semi)quantitative thermodynamic analysis, we discovered that 1) the unfavorable interaction of trehalose with hydrophobic surfaces is the dominant factor in its effect on protein stability, 2) the favorable interaction of trehalose with polar amides enables it to inhibit polyQ-mediated protein aggregation and the aggregation of denatured protein in general, and 3) the favorable interaction of trehalose with phosphate oxygens, together with its unfavorable interaction with aliphatic carbons, enables trehalose to preserve membrane integrity in aqueous solution. These results provide a basis for a full understanding of the role of trehalose in biopolymer homeostasis and the reason behind its evolutionary selection as an osmolyte, as well as for a better application of trehalose as a chemical chaperone.

  20. Its Preferential Interactions with Biopolymers Account for Diverse Observed Effects of Trehalose

    Science.gov (United States)

    Hong, Jiang; Gierasch, Lila M.; Liu, Zhicheng

    2015-01-01

    Biopolymer homeostasis underlies the health of organisms, and protective osmolytes have emerged as one strategy used by Nature to preserve biopolymer homeostasis. However, a great deal remains unknown about the mechanism of action of osmolytes. Trehalose, as a prominent example, stabilizes proteins against denaturation by extreme temperature and denaturants, preserves membrane integrity upon freezing or in dry conditions, inhibits polyQ-mediated protein aggregation, and suppresses the aggregation of denatured proteins. The underlying thermodynamic mechanisms of such diverse effects of trehalose remain unclear or controversial. In this study, we applied the surface-additive method developed in the Record laboratory to attack this issue. We characterized the key features of trehalose-biopolymer preferential interactions and found that trehalose has strong unfavorable interactions with aliphatic carbon and significant favorable interactions with amide/anionic oxygen. This dissection has allowed us to elucidate the diverse effects of trehalose and to identify the crucial functional group(s) responsible for its effects. With (semi)quantitative thermodynamic analysis, we discovered that 1) the unfavorable interaction of trehalose with hydrophobic surfaces is the dominant factor in its effect on protein stability, 2) the favorable interaction of trehalose with polar amides enables it to inhibit polyQ-mediated protein aggregation and the aggregation of denatured protein in general, and 3) the favorable interaction of trehalose with phosphate oxygens, together with its unfavorable interaction with aliphatic carbons, enables trehalose to preserve membrane integrity in aqueous solution. These results provide a basis for a full understanding of the role of trehalose in biopolymer homeostasis and the reason behind its evolutionary selection as an osmolyte, as well as for a better application of trehalose as a chemical chaperone. PMID:26153711

  1. Aggregation on heterogeneous surface

    Institute of Scientific and Technical Information of China (English)

    Lu Hang-Jun; Wu Feng-Min; Fang Yun-Zhang

    2004-01-01

    Chessboard-like substrates are introduced in this paper, in order to study the diffusion-limited aggregation (DLA)and the motion of poly-atoms on heterogeneous surfaces. The effect of morphology of such substrates upon the cluster aggregation is investigated using the Monte Carlo simulation. It is found that the growth process and the cluster morphology are governed by the energetic topography of the substrates. Our simulation also indicate that the island density and the fractal dimension of the clusters depend strongly on the substrate topography and the activation energy.

  2. Dye staining and excavation of a lateral preferential flow network

    Directory of Open Access Journals (Sweden)

    A. E. Anderson

    2009-06-01

    Full Text Available Preferential flow paths have been found to be important for runoff generation, solute transport, and slope stability in many areas around the world. Although many studies have identified the particular characteristics of individual features and measured the runoff generation and solute transport within hillslopes, very few studies have determined how individual features are hydraulically connected at a hillslope scale. In this study, we used dye staining and excavation to determine the morphology and spatial pattern of a preferential flow network over a large scale (30 m. We explore the feasibility of extending small-scale dye staining techniques to the hillslope scale. We determine the lateral preferential flow paths that are active during the steady-state flow conditions and their interaction with the surrounding soil matrix. We also calculate the velocities of the flow through each cross-section of the hillslope and compare them to hillslope scale applied tracer measurements. Finally, we investigate the relationship between the contributing area and the characteristics of the preferential flow paths. The experiment revealed that larger contributing areas coincided with highly developed and hydraulically connected preferential flow paths that had flow with little interaction with the surrounding soil matrix. We found evidence of subsurface erosion and deposition of soil and organic material laterally and vertically within the soil. These results are important because they add to the understanding of the runoff generation, solute transport, and slope stability of preferential flow-dominated hillslopes.

  3. Diffusion in aggregated soil.

    NARCIS (Netherlands)

    Rappoldt, C.

    1992-01-01

    The structure of an aggregated soil is characterized by the distribution of the distance from an arbitrary point in the soil to the nearest macropore or crack. From this distribution an equivalent model system is derived to which a diffusion model can be more easily applied. The model system consist

  4. Carrier Aggregation for LTE-Advanced

    DEFF Research Database (Denmark)

    Pedersen, Klaus Ingemann; Frederiksen, Frank; Rosa, Claudio;

    2011-01-01

    aggregated. This paper presents a summary of the supported CA scenarios as well as an overview of the CA functionality for LTE-Advanced with special emphasis on the basic concept, control mechanisms, and performance aspects. The discussion includes definitions of the new terms primary cell (PCell) and......Carrier aggregation (CA) is one of the key features for LTE-Advanced. By means of CA, users gain access to a total bandwidth of up to 100 MHz in order to meet the IMT-Advanced requirements. The system bandwidth may be contiguous, or composed of several non-contiguous bandwidth chunks, which are...... secondary cell (SCell), mechanisms for activation and deactivation of CCs, and the new cross-CC scheduling functionality for improved control channel optimizations. We also demonstrate how CA can be used as an enabler for simple yet effective frequency domain interference management schemes. In particular...

  5. Frequency, Size, and Localization of Bacterial Aggregates on Bean Leaf Surfaces

    Science.gov (United States)

    Monier, J.-M.; Lindow, S. E.

    2004-01-01

    Using epifluorescence microscopy and image analysis, we have quantitatively described the frequency, size, and spatial distribution of bacterial aggregates on leaf surfaces of greenhouse-grown bean plants inoculated with the plant-pathogenic bacterium Pseudomonas syringae pv. syringae strain B728a. Bacterial cells were not randomly distributed on the leaf surface but occurred in a wide range of cluster sizes, ranging from single cells to over 104 cells per aggregate. The average cluster size increased through time, and aggregates were more numerous and larger when plants were maintained under conditions of high relative humidity levels than under dry conditions. The large majority of aggregates observed were small (less than 100 cells), and aggregate sizes exhibited a strong right-hand-skewed frequency distribution. While large aggregates are not frequent on a given leaf, they often accounted for the majority of cells present. We observed that up to 50% of cells present on a leaf were located in aggregates containing 103 cells or more. Aggregates were associated with several different anatomical features of the leaf surface but not with stomates. Aggregates were preferentially associated with glandular trichomes and veins. The biological and ecological significance of aggregate formation by epiphytic bacteria is discussed. PMID:14711662

  6. Phosphorus Speciation and Sorption Processes in Preferential flow paths and Soil Matrix in Forested Podzolic Till Soil

    Science.gov (United States)

    Saastamoinen, S.; Laine-Kaulio, H.; Klöve, B.

    2009-04-01

    The importance of preferential flow paths in nutrient leaching and subsurface transport has been identified in several studies mainly on agricultural soils. In forest soils research, decayed root channels, stone surfaces and other secondary soil structures have shown to affect unsaturated flow in glacial till soil. Until recently, the focus has been on nitrogen and carbon dynamics in the preferential flow paths. Preferential flow may also have a fundamental role in phosphorus (P) sorption processes and transport from forested till soils to surface waters. The main objectives of this study were to determine how preferential flow paths affect to P speciation, sorption and leaching in forested podzolic till soil. Field experiments were conducted in mixed coniferous forest, with soil type of glacial sandy till classified as Haplic Podzol. The first experiment was conducted in Ranua, Northern Finland. The preferential flow paths were identified by introducing Acid Blue 9 dye tracer to a 1 m2 study plot. The soil profile was vertically sliced and samples were collected from the stained preferential flow paths and unstained soil matrix. Ammonium-oxalate extracted trace elements and P, total and inorganic P, inorganic P fractions and organic P forms (31P-NMR spectroscopy) were analyzed from the samples. In the second experiment in Sotkamo, Eastern Finland, three 1 m2 study plots were selected from a forested hillslope: top, middle and bottom slope. The detection of preferential flow paths and the sampling procedure was identical to the first plot experiment. Samples were analyzed for ammonium-oxalate extracted trace elements and P. Also, the effect of reaction time, P concentration and temperature on the sorption process in preferential flow paths and soil matrix was studied by kinetic batch-type sorption experiments. Stone surfaces were the most dominant preferential flow paths and contained lower oxalate-extracted and total P concentrations than the soil matrix in all

  7. Dye staining and excavation of a lateral preferential flow network

    Directory of Open Access Journals (Sweden)

    A. E. Anderson

    2008-04-01

    Full Text Available Preferential flow features have been found to be important for runoff generation, solute transport, and slope stability in many areas around the world. Although many studies have identified the particular characteristics of individual features and measured the runoff generation and solute transport within hillslopes, no studies have determined how individual features are hydraulically connected at a hillslope scale. In this study, we used dye staining and excavation to determine the morphology and spatial pattern of a preferential flow network over a large scale (30 m. We explore the feasibility of extending small-scale dye staining techniques to the hillslope scale. We determine the lateral preferential flow features that are active during the steady state flow conditions and their interaction with the surrounding soil matrix. We also calculate the velocities of the flow through each cross-section of the hillslope and compare them to hillslope scale applied tracer measurements. Finally, we investigate the relationship between the contributing area and the characteristics of the preferential features. The experiment revealed that larger contributing areas coincided with highly developed and hydraulically connected preferential features that had flow with little interaction with the surrounding soil matrix. We found evidence of subsurface erosion and deposition of soil and organic material laterally and vertically within the soil. These results are important because they add to the understanding of the runoff generation, solute transport, and slope stability of these types of hillslopes.

  8. Inverse Simulation of Field Infiltration Experiment Counting Preferential Flow

    Science.gov (United States)

    Zumr, David; Snehota, Michal; Nemcova, Renata; Dohnal, Michal; Cislerova, Milena

    2010-05-01

    The field tension and ponded infiltration experiments were conducted to monitor and describe irregularities of moisture propagation and to estimate the soil hydraulic properties (Distric Cambisol, Korkusova Hut, Sumava). On these soils the preferential pathways have been observed in several scales with the use of dye tracers, MRI and CT imaging. Preferential behavior was detected also during laboratory infiltration experiments. The flow irregularities are credited to variable air entrapment at the beginning of infiltrations. The field infiltration experiment was carried out in a shallow pit for a period of one day. The upper boundary condition was controlled by the tension disk infiltrometer, the propagation of a water front was monitored by two tensiometers installed in two depths below the infiltration disk. The propagation of saline solution front during ponded infiltration was visualized with high resolution electrical resistivity tomography (ERT). Infiltration experiments were monitored with TDR probes, tensiometers and ERT. Zones of preferential flow were determined through analyses of photographs taken during laboratory dye tracer infiltration experiments performed on undisturbed soil samples. Connectivity, volumetric ratio and spatial development of preferential pathways were evaluated as the necessary information for numerical simulations of flow using dual-permeability approach. 2D axisymetric numerical simulations were conducted to evaluate the results of the experiment. The parameter estimator PEST coupled with the simulation code S2D_DUAL (Vogel et al., 2000) were employed. Two different approaches were used: 1. Single-domain approach based on Richards' equation. 2. Dual-permeability approach based on two interacting water flow domains (matrix and preferential domains), each governed by one Richards' equation. Concerning the existence of preferential flow on investigated soil, the dual-permeability model gives a better picture of the flow regime. The

  9. Proteins aggregation and human diseases

    Science.gov (United States)

    Hu, Chin-Kun

    2015-04-01

    Many human diseases and the death of most supercentenarians are related to protein aggregation. Neurodegenerative diseases include Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), frontotemporallobar degeneration, etc. Such diseases are due to progressive loss of structure or function of neurons caused by protein aggregation. For example, AD is considered to be related to aggregation of Aβ40 (peptide with 40 amino acids) and Aβ42 (peptide with 42 amino acids) and HD is considered to be related to aggregation of polyQ (polyglutamine) peptides. In this paper, we briefly review our recent discovery of key factors for protein aggregation. We used a lattice model to study the aggregation rates of proteins and found that the probability for a protein sequence to appear in the conformation of the aggregated state can be used to determine the temperature at which proteins can aggregate most quickly. We used molecular dynamics and simple models of polymer chains to study relaxation and aggregation of proteins under various conditions and found that when the bending-angle dependent and torsion-angle dependent interactions are zero or very small, then protein chains tend to aggregate at lower temperatures. All atom models were used to identify a key peptide chain for the aggregation of insulin chains and to find that two polyQ chains prefer anti-parallel conformation. It is pointed out that in many cases, protein aggregation does not result from protein mis-folding. A potential drug from Chinese medicine was found for Alzheimer's disease.

  10. Preferential Voting in Denmark: How, Why, and to What Effect?

    DEFF Research Database (Denmark)

    Elklit, Jørgen

    The paper provides an overview of (1) the Danish system for casting a preferential – or personal – vote in a proportional list system and (2) how seats are subsequently allocated. Denmark differs from most (all?) preferential list PR systems by letting the parties themselves (actually the parties...... is then briefly compared to the Swedish and the Finnish systems before a few empirical results from Danish impact studies are presented. Finally, a model attempts to illustrate how the various explanatory factors interact to produce the parties’ votes in the Danish multi-member constituencies....

  11. A Generalized Preferential Attachment Model for Complex Systems

    CERN Document Server

    Yamasaki, K; Fu, D; Buldyrev, S V; Pammolli, F; Riccaboni, M; Stanley, H E; Yamasaki, Kazuko; Matia, Kaushik; Fu, Dongfeng; Buldyrev, Sergey V.; Pammolli, Fabio; Riccaboni, Massimo

    2005-01-01

    Complex systems can be characterized by classes of equivalency of their elements defined according to system specific rules. We propose a generalized preferential attachment model to describe the class size distribution. The model postulates preferential growth of the existing classes and the steady influx of new classes. We investigate how the distribution depends on the initial conditions and changes from a pure exponential form for zero influx of new classes to a power law with an exponential cutoff form when the influx of new classes is substantial. We apply the model to study the growth dynamics of pharmaceutical industry.

  12. Declustering of clustered preferential sampling for histogram and semivariogram inference

    Science.gov (United States)

    Olea, R.A.

    2007-01-01

    Measurements of attributes obtained more as a consequence of business ventures than sampling design frequently result in samplings that are preferential both in location and value, typically in the form of clusters along the pay. Preferential sampling requires preprocessing for the purpose of properly inferring characteristics of the parent population, such as the cumulative distribution and the semivariogram. Consideration of the distance to the nearest neighbor allows preparation of resampled sets that produce comparable results to those from previously proposed methods. Clustered sampling of size 140, taken from an exhaustive sampling, is employed to illustrate this approach. ?? International Association for Mathematical Geology 2007.

  13. Connecting ecohydrology and hydropedology in desert shrubs: stemflow as a source of preferential flow in soils

    Directory of Open Access Journals (Sweden)

    Henry Lin

    2009-07-01

    Full Text Available Ecohydrology and hydropedology are two emerging fields that are interconnected. In this study, we demonstrate stemflow hydrology and preferential water flow along roots in two desert shrubs (H. scoparium and S. psammophila in the south fringe of Mu Us sandy land in North China. Stemflow generation and subsequent movement within soil-root system were investigated during the growing seasons from 2006 to 2008. The results indicated that the amount of stemflow in H. scoparium averaged 3.4% of incident gross rainfall with a range of 2.3–7.0%, while in S. psammophila stemflow averaged 6.3% with a range of 0.2–14.2%. Stemflow was produced from rainfall events with total amount more than 1 mm for both shrubs. The average funneling ratio (the ratio of rainfall amount delivered to the base of the tree to the rainfall that would have reached the ground should the tree were not present was 77.8 and 48.7 for H. scoparium and S. psammophila, respectively, indicating that branches and stems were fully contributing to stemflow generation and thereby provided sources of water for possible preferential flow into deeper soil layer. Analysis of Rhodamine-B dye distribution under the shrubs showed that root channels were preferential pathways for the movement of most stemflow water into the soil. Distribution of soil water content under the shrubs with and without stemflow ascertained that stemflow was conducive to concentrate and store water in deeper layers in the soil profiles, which may create favorable soil water conditions for plant growth under arid conditions. Accordingly, a clear linkage between aboveground ecohydrology and belowground hydropedology in the desert shrubs is worth noticing, whereby an increase in stemflow would result in an increase in soil hydrologic heterogeneity.

  14. Advanced Measurements of the Aggregation Capability of the MPT Network Layer Multipath Communication Library

    Directory of Open Access Journals (Sweden)

    Gábor Lencse

    2015-05-01

    Full Text Available The MPT network layer multipath communicationlibrary is a novel solution for several problems including IPv6transition, reliable data transmission using TCP, real-time transmissionusing UDP and also wireless network layer routingproblems. MPT can provide an IPv4 or an IPv6 tunnel overone or more IPv4 or IPv6 communication channels. MPT canalso aggregate the capacity of multiple physical channels. In thispaper, the channel aggregation capability of the MPT libraryis measured up to twelve 100Mbps speed channels. Differentscenarios are used: both IPv4 and IPv6 are used as the underlyingand also as the encapsulated protocols and also both UDP andTCP are used as transport protocols. In addition, measurementsare taken with both 32-bit and 64-bit version of the MPT library.In all cases, the number of the physical channels is increased from1 to 12 and the aggregated throughput is measured.

  15. Absorption Spectra of Astaxanthin Aggregates

    CERN Document Server

    Olsina, Jan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption maximum of monomeric astaxanthin (470-495 nm depending on solvent) are caused by excitonic interaction between aggregated molecules. We applied molecular dynamics simulations to elucidate structure of astaxanthin dimer in water, and the resulting structure was used as a basis for calculations of absorption spectra. Absorption spectra of astaxanthin aggregates in hydrated dimethylsulfoxide were calculated using molecular exciton model with the resonance interaction energy between astaxanthin monomers constrained by semi-e...

  16. Hydrophobic aggregation of ultrafine kaolinite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-ping; HU Yue-hua; LIU Run-Qing

    2008-01-01

    The hydrophobic aggregation of ultrafine kaolinite in cationic surfactant suspension was investigated by sedimentation test, zeta potential measurement and SEM observation. SEM images reveal that kaolinite particles show the self-aggregation of edge-face in acidic media, the aggregation of edge-face and edge-edge in neutral media, and the dispersion in alkaline media due to electrostatic repulsion. In the presence of the dodecylammonium acetate cationic surfactant and in neutral and alkaline suspension, the hydrophobic aggregation of face-face is demonstrated. The zeta potential of kaolinite increases with increasing the concentration of cationic surfactant. The small and loose aggregation at a low concentration but big and tight aggregation at a high concentration is presented At pH=7 alkyl quarterly amine salt CTAB has the best hydrophobic aggregation among three cationic surfactants, namely, dodecylammonium acetate, alkyl quarterly amine salts 1227 and CTAB.

  17. Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

    OpenAIRE

    Fér Miroslav; Leue Martin; Kodešová Radka; Gerke Horst H.; Ellerbrock Ruth H.

    2016-01-01

    The organo-mineral coatings of soil aggregates, cracks, and biopores control sorption and macropore-matrix exchange during preferential flow, in particular in the clay-illuvial Bt-horizon of Luvisols. The soil organic matter (SOM) composition has been hypothesized to explain temporal changes in the hydraulic properties of aggregate surfaces. The objective of this research was to find relations between the temporal change in wettability, in terms of droplet infiltration dynamics, and the SOM c...

  18. Copper Smelters Ask for Resumption of the Preferential Tax

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    <正>China’s major copper smelters have asked the related government authorities to resume the preferential tax policies on the export of copper and gold. These policies, just eliminated in January this year, allow the smelters to export copper and gold free from tax payment.

  19. Predicting Alcohol, Cigarette, and Marijuana Use from Preferential Music Consumption

    Science.gov (United States)

    Oberle, Crystal D.; Garcia, Javier A.

    2015-01-01

    This study investigated whether use of alcohol, cigarettes, and marijuana may be predicted from preferential consumption of particular music genres. Undergraduates (257 women and 78 men) completed a questionnaire assessing these variables. Partial correlation analyses, controlling for sensation-seeking tendencies and behaviors, revealed that…

  20. Significance of tree roots for preferential infiltration in stagnic soils

    Directory of Open Access Journals (Sweden)

    B. Lange

    2009-10-01

    Full Text Available It is generally recognized that roots have an effect on infiltration. In this study we analysed the relation between root length distributions from Norway spruce (Picea abies (L. Karst, silver fir (Abies alba Miller, European beech (Fagus sylvatica L. and preferential infiltration in stagnic soils in the northern Pre-Alps in Switzerland. We conducted irrigation experiments (1 m2 and recorded water content variations with time domain reflectometry (TDR. A rivulet approach was applied to characterise preferential infiltration. Roots were sampled down to a depth of 0.5 to 1 m at the same position where the TDR-probes had been inserted and digitally measured. The basic properties of preferential infiltration, film thickness of mobile water and the contact length between soil and mobile water in the horizontal plane are closely related to root densities. An increase in root density resulted in an increase in contact length, but a decrease in film thickness. We modelled water content waves based on root densities and identified a range of root densities that lead to a maximum volume flux density and infiltration capacity. These findings provide convincing evidence that tree roots in stagnic soils represent the pore system that carries preferential infiltration. Thus, the presence of roots should improve infiltration.

  1. Preferential treatment of women and psychological reactance theory: An experiment

    NARCIS (Netherlands)

    A.J. Vrugt

    1992-01-01

    187 male academic staff members read a low- or high-threat (freedom restricting) description of measures for the preferential treatment of women in job selection for academic staff functions. The high-threat condition evoked more psychological reactance than the low-threat condition. Ss with high se

  2. Infants' Preferential Attention to Sung and Spoken Stimuli

    Science.gov (United States)

    Costa-Giomi, Eugenia; Ilari, Beatriz

    2014-01-01

    Caregivers and early childhood teachers all over the world use singing and speech to elicit and maintain infants' attention. Research comparing infants' preferential attention to music and speech is inconclusive regarding their responses to these two types of auditory stimuli, with one study showing a music bias and another one…

  3. Unified Model for Generation Complex Networks with Utility Preferential Attachment

    Institute of Scientific and Technical Information of China (English)

    WU Jian-Jun; GAO Zi-You; SUN Hui-Jun

    2006-01-01

    In this paper, based on the utility preferential attachment, we propose a new unified model to generate different network topologies such as scale-free, small-world and random networks. Moreover, a new network structure named super scale network is found, which has monopoly characteristic in our simulation experiments. Finally, the characteristics ofthis new network are given.

  4. Coupled vertical and lateral preferential flow on a forested slope

    Science.gov (United States)

    Buttle, J. M.; McDonald, D. J.

    2002-05-01

    Coupling of vertical and lateral preferential flow paths was examined on a forested slope with thin soil cover during artificial irrigations. Point-scale infiltration was measured at sites with differing soil macroporosities using vertical profiles of time domain reflectometry probes and suction samplers. Lateral fluxes of water and solutes from the slope were determined at a through flow trench. Sites with greater macroporosities tended to exhibit vertical preferential flow, while infiltration at sites with relatively small macroporosities was largely by vertical propagation of a well defined wetting front through the soil profile. Generation of vertical preferential flow at sites with relatively large macroporosities increased with input intensity. Lateral macropores made a minor contribution to slope runoff. Instead, runoff largely occurred in a thin saturated layer at the soil-bedrock interface, both in a highly conductive zone at the bedrock surface and in the overlying saturated soil matrix. Some assumptions underlying the use of isotopic and geochemical tracers to study runoff generation are called into question by complex mixing of event and pre-event water in this saturated layer. Soil depth, bedrock topography, and antecedent soil wetness determine the thickness, connectivity, and upslope extent of the pre-event saturated layer above the bedrock surface. These, in turn, control whether vertical preferential and matrix flow reaching the bedrock surface participate in slope runoff.

  5. Susceptibility and predictability of conditions for preferential flow

    NARCIS (Netherlands)

    Wang, Z.; Feyen, J.; Ritsema, C.J.

    1998-01-01

    Preferential flow in the field might be caused by various factors and is difficult to observe in situ. This experimental study was designed to identify the combined effects of air entrapment, surface desaturation (suction head), soil layering, and water repellency (hydrophobicity) of the porous medi

  6. Soil surfactant stops water repellency and preferential flow paths

    NARCIS (Netherlands)

    Oostindie, K.; Dekker, L.W.; Wesseling, J.G.; Ritsema, C.J.

    2008-01-01

    This study reports the effects of a soil surfactant on reduction and prevention of water repellency and preferential flow paths in a sandy soil of a golf course fairway, located at Bosch en Duin near Utrecht, the Netherlands. The golf course is constructed on inland dunes composed of fine sand with

  7. Preferential interactions and the effect of protein PEGylation

    DEFF Research Database (Denmark)

    Holm, Louise Stenstrup; Thulstrup, Peter Waaben; Kasimova, Marina Robertovna;

    2015-01-01

    enthalpy was decreased to half the value for PEGylated lysozyme. The ratio between calorimetric and van't Hoff enthalpy suggests that our PEGylated lysozyme is a dimer. CONCLUSION/SIGNIFICANCE: The PEGylated model protein displayed similar stability responses to the addition of preferentially active...

  8. Preferential Petroleum Migration Pathways in Eastern Pearl River Mouth Basin,Offshore South China Sea

    Institute of Scientific and Technical Information of China (English)

    Yu Jianning; Zou Huayao; Gong Zaisheng

    2009-01-01

    Secondary petroleum migration in the eastern Pearl River Mouth basin was modeled using the three-dimensional PATHWAYSTM model,which assumes that the positions of petroleum migration pathways are controlled by the morphology of the sealing surfaces.The modeling results have accurately predicted the petroleum occurrences.Most commercial petroleum accumulations are along the predicted preferential petroleum migration pathways (PPMP),and most large fields (petroleum reserves greater than 1×108 t) have more than one preferential petroleum migration pathways to convey petroleum to the traps.The lateral migration distance for oil in the LH11-1 field,the largest oilfield so far discovered in the Pearl River Mouth basin,was more than 80 km.The case study suggests that in lacustrine fault basins,petroleum can migrate over a long distance to form large oilfields without driving force from groundwater flow.The focusing of petroleum originating from a large area of the generative kitchens into restricted channels seems to be essential not only for long-range petroleum migration in hydrostatic conditions,but also for the formation of large oil or gas fields.The strong porosity and permeability heterogeneities of the carrier beds and the relatively high prediction accuracy by a model that does not take into consideration of the effect of heterogeneity suggest that the positions of petroleum migration pathways in heterogeneous carrier beds with relatively large dipping angles are determined primarily by the morphology of the sealing surfaces at regional scales.

  9. Frame Aggregation Mechanism for High-Throughput 802.11n Wlans

    Directory of Open Access Journals (Sweden)

    Jyoti Kolap

    2012-07-01

    Full Text Available IEEE 802.11n Draft is next-generation wireless LAN standard. This article gives detailed description and comparative study of A-MPDU and Two level frame aggregation mechanisms proposed in the latest 802.11n draft standard, which improve extensively the channel efficiency and data throughput. Ns 2 simulator is used for simulation of 802.11n WLAN frame aggregation. Simulation results confirm that AMPDU, and Two level frame aggregation methods improve extensively data throughput. It analyse the performance of each frame aggregation scheme in distinct scenarios, and it conclude that overall, the two-level aggregation can improve throughput performance of 802.11n. Two level aggregation can more effectively deliver data from multiple sources, PDR rate is much higher with much lower delay and Two level aggregation consumed less energy as compared with A-MPDU approach..

  10. Aggregate Demand and Supply

    OpenAIRE

    Farmer, Roger E.A.

    2007-01-01

    This paper is part of a broader project that provides a microfoundation to the General Theory of J.M. Keynes. I call this project 'old Keynesian economics' to distinguish it from new-Keynesian economics, a theory that is based on the idea that to make sense of Keynes we must assume that prices are sticky. I describe a multi-good model in which I interpret the definitions of aggregate demand and supply found in the General Theory through the lens of a search theory of the labor market. I argue...

  11. Do Karstic Unsaturated Zones Have the Fastest Preferential Flow?

    Science.gov (United States)

    Nimmo, J. R.; Perkins, K. S.

    2013-12-01

    There is strong evidence that unsaturated-zone travel times for preferential flow, unlike those for diffuse flow, mostly fall within a relatively small range, even for a wide variety of media and conditions [Nimmo, 2007, Water Resources Research]. We have calculated travel times for preferential flow observations published in the last seven years, finding a range of travel velocities with a greater maximum than was previously recognized. The instances of faster transport, however, are predominantly for karst or other materials in which water flow may strongly influence the creation and development of preferential flow paths. These findings motivate a hypothesis: in media where the matrix is soluble, erodible, or otherwise vulnerable to enlargement by flowing water, this flow acts to reduce flow impediments within a macropore network. This might be thought of as a sculpting process in which water carves its conduit into a smoother, larger, less constrictive shape, as discussed in connection with soil pipes [Jones, 2010, Hydrological Processes]. Known developmental processes of karst and epikarst are consistent with this hypothesis. Its acceptance would open doors to expanded use of optimality and thermodynamic principles to understand and predict preferential flow. It also could lead to new modes of hydraulic characterization of subsurface media with regard to unsaturated flow, which are much needed as the difficulty of measuring hydraulic properties of the unsaturated zone is a major barrier to the advance of hydrologic science. In practical terms, a new guideline may be justified: in unsaturated karst or other materials in which flowing water may enhance flowpaths, preferential transport rates in general may be several times faster than through media without such pore-developmental processes.

  12. The stability of soil aggregates in tilled fallow areas in Hyderabad district, Pakistan

    Directory of Open Access Journals (Sweden)

    Tagar Ahmed

    2015-12-01

    Full Text Available Arid areas are particularly susceptible to soil erosion due to long dry periods and sudden heavy downpours. This study investigates the aggregate size distribution and aggregate stability of twelve tilled fallow areas of Hyderabad district, Sindh, Pakistan. This study determined aggregate size distribution by dry sieving to evaluate the seedbed condition and aggregate stability using wet sieving to assess the susceptibility of tilled fallow areas to soil erosion. The aggregate size distribution of the soils of the selected areas was highly variable. Gulistan-e-Sarmast had the largest number of clods (51.0% followed by Kohsar (49.0%, Latifabad # 10 (41.10% and Daman-e-Kohsar (39.0%. Fazal Sun City, the left side of the Indus River, the Village Nooral Detha and the left side of the Abdullah Sports city had a greater number of large (>8.0 mm and small aggregates (<0.5 mm. The optimum aggregate size distribution was found in the left side of the channel, which had the largest number of aggregates (50.50% in the 0.5–8.0 mm sieve size range. Maximum aggregate stability (AS was found in Gulistan-e-Sarmast (46%, Kohsar (42% and Latifabad # 10 (34%, while all other soils had minimum aggregate stability (<14%. The minimum aggregate stabilities demonstrate that the tilled fallow areas of Hyderabad district are highly susceptible to erosion. Therefore, the present study suggests investigating potential ways to enhance the aggregate stabilities of soils.

  13. Increasing the efficiency of solute leaching: impacts of flow interruption with drainage of the ``preferential flow paths''

    Science.gov (United States)

    Cote, C. M.; Bristow, K. L.; Ross, P. J.

    2000-05-01

    Most soils contain preferential flow paths that can impact on solute mobility. Solutes can move rapidly down the preferential flow paths with high pore-water velocities, but can be held in the less permeable region of the soil matrix with low pore-water velocities, thereby reducing the efficiency of leaching. In this study, we conducted leaching experiments with interruption of the flow and drainage of the main flow paths to assess the efficiency of this type of leaching. We compared our experimental results to a simple analytical model, which predicts the influence of the variations in concentration gradients within a single spherical aggregate (SSA) surrounded by preferential flow paths on leaching. We used large (length: 300 mm, diameter: 216 mm) undisturbed field soil cores from two contrasting soil types. To carry out intermittent leaching experiments, the field soil cores were first saturated with tracer solution (CaBr 2), and background solution (CaCl 2) was applied to mimic a leaching event. The cores were then drained at 25- to 30-cm suction to empty the main flow paths to mimic a dry period during which solutes could redistribute within the undrained region. We also conducted continuous leaching experiments to assess the impact of the dry periods on the efficiency of leaching. The flow interruptions with drainage enhanced leaching by 10-20% for our soils, which was consistent with the model's prediction, given an optimised "equivalent aggregate radius" for each soil. This parameter quantifies the time scales that characterise diffusion within the undrained region of the soil, and allows us to calculate the duration of the leaching events and interruption periods that would lead to more efficient leaching. Application of these methodologies will aid development of strategies for improving management of chemicals in soils, needed in managing salts in soils, in improving fertiliser efficiency, and in reclaiming contaminated soils.

  14. Stratification of colloidal aggregation coupled with sedimentation.

    Science.gov (United States)

    González, Agustín E

    2006-12-01

    One of the consequences of sedimentation in colloidal aggregation is the stratification of the system in the sense that, after a sufficiently long elapsed time, the large clusters lie preferentially at the bottom zones of the confinement prism, and the structural and dynamical quantities describing the aggregates depend on the depth at which they are measured. A few years ago a computer simulation using particles for colloidal aggregation coupled with sedimentation was proposed by the author [A. E. González, Phys. Rev. Lett. 86, 1243 (2001)]. In that simulation, due to computational limitations, the mentioned quantities were averaged over all clusters in the prism, independently of the depth at which they were located, in order to have good statistics for the evaluation of the cluster fractal dimension and the cluster size distribution function. In this work we present a computer simulation using particles of colloidal aggregation coupled with sedimentation, for which the clusters in the simulation box represent those clusters inside a layer at a fixed depth and of arbitrary thickness in the prism. It would then be possible to compare the results with an eventual validation experiment, in which an aggregating sample is sipped out with a pipette at a fixed depth in the prism and subjected to further studies, or with a light scattering study in which the laser beam is focused at a fixed depth in the system. We confirm the acceleration of the aggregation rate, followed by a slowing down, compared with an aggregating system driven purely by diffusion (DLCA). In the present system, the large clusters when drifting downwards sweep smaller ones, which in turn occlude the holes and cavities of these large clusters, increasing in this way their compacticity. We also confirm that (i) in some cases of sedimentation strengths and layer depths, the mean width (perpendicular to the gravitational field direction) and the mean height of the large settling clusters scale with the

  15. Inertial (non-Darcian) channeled seepage flow

    Science.gov (United States)

    Foda, Mostafa A.

    1994-10-01

    A slow wave solution is identified for an infinite elastic medium intersected by a two-dimensional fluid channel. Because the wave speed is much slower than the medium's elastic shear wave, the response in the elastic medium is governed by elastostatics. The inertia of the wave is essentially focused in the fluid channel. Furthermore, wave damping is caused by fluid viscous friction on the channel in an elastic solid. It is proposed that these solutions may also be used in the case of a granular porous medium. The seepage channels would then represent a network of preferential flow paths. Therefore we would allow, in this case, the channel porosity to be different from the average granular porosity. For a strongly channel seepage flow or for a low channel porosity the solution is shown to approach that of a single-channel solution, giving rise to a slow propagating wave mode. On the other hand, for weak channeling or nearly `homogeneous' seepage flow the solution is shown to reproduce Biot's (1956) critically damped wave of the second kind. It is proposed that the resonance observed by Foda and Tzang (1994) are in the form of these strongly channeled wave modes.

  16. Green Frame Aggregation Scheme for IEEE 802.11n Networks

    KAUST Repository

    Alaslani, Maha S.

    2015-04-01

    Frame aggregation is one of the major MAC layer enhancements in the IEEE 802.11 family that boosts the network throughput performance. It aims to achieve higher throughput by transmitting huge amount of data in a single transmit oppor- tunity. With the increasing awareness of energy e ciency, it has become vital to rethink about the design of such frame aggregation protocol. Aggregation techniques help to reduce energy consumption over ideal channel conditions. However, in a noisy channel environment, a new energy-aware frame aggregation scheme is required. In this thesis, a novel Green Frame Aggregation (GFA) scheduling scheme has been proposed and evaluated. GFA optimizes the aggregate size based on channel quality in order to minimize the consumed energy. GFA selects the optimal sub-frame size that satisfies the loss constraint for real-time applications as well as the energy budget of the ideal channel situations. The design, the implementation, and evaluation of GFA using testbed deployment is done. The experimental analysis shows that GFA outperforms the conventional frame aggregation methodology in terms of energy e ciency by about 6⇥ in the presence of severe interference conditions. Moreover, GFA also outperforms the static frame sizing method in terms of network goodput and maintains almost the same end- to-end latency.

  17. Modifiers of mutant huntingtin aggregation

    OpenAIRE

    Teuling, Eva; Bourgonje, Annika; Veenje, Sven; Thijssen, Karen; Boer, Jelle de; van der Velde, Joeri; Swertz, Morris; Nollen, Ellen

    2011-01-01

    Protein aggregation is a common hallmark of a number of age-related neurodegenerative diseases, including Alzheimer’s, Parkinson’s, and polyglutamine-expansion disorders such as Huntington’s disease, but how aggregation-prone proteins lead to pathology is not known. Using a genome-wide RNAi screen in a C. elegans-model for polyglutamine aggregation, we previously identified 186 genes that suppress aggregation. Using an RNAi screen for human orthologs of these genes, we here present 26 human g...

  18. Novel aspects of platelet aggregation

    Directory of Open Access Journals (Sweden)

    Roka-Moya Y. M.

    2014-01-01

    Full Text Available The platelet aggregation is an important process, which is critical for the hemostatic plug formation and thrombosis. Recent studies have shown that the platelet aggregation is more complex and dynamic than it was previously thought. There are several mechanisms that can initiate the platelet aggregation and each of them operates under specific conditions in vivo. At the same time, the influence of certain plasma proteins on this process should be considered. This review intends to summarize the recent data concerning the adhesive molecules and their receptors, which provide the platelet aggregation under different conditions.

  19. Aggregation dynamics of rigid polyelectrolytes

    Science.gov (United States)

    Tom, Anvy Moly; Rajesh, R.; Vemparala, Satyavani

    2016-01-01

    Similarly charged polyelectrolytes are known to attract each other and aggregate into bundles when the charge density of the polymers exceeds a critical value that depends on the valency of the counterions. The dynamics of aggregation of such rigid polyelectrolytes are studied using large scale molecular dynamics simulations. We find that the morphology of the aggregates depends on the value of the charge density of the polymers. For values close to the critical value, the shape of the aggregates is cylindrical with height equal to the length of a single polyelectrolyte chain. However, for larger values of charge, the linear extent of the aggregates increases as more and more polymers aggregate. In both the cases, we show that the number of aggregates decrease with time as power laws with exponents that are not numerically distinguishable from each other and are independent of charge density of the polymers, valency of the counterions, density, and length of the polyelectrolyte chain. We model the aggregation dynamics using the Smoluchowski coagulation equation with kernels determined from the molecular dynamics simulations and justify the numerically obtained value of the exponent. Our results suggest that once counterions condense, effective interactions between polyelectrolyte chains short-ranged and the aggregation of polyelectrolytes are diffusion-limited.

  20. Fractal Aggregation Under Rotation

    Institute of Scientific and Technical Information of China (English)

    WUFeng-Min; WULi-Li; LUHang-Jun; LIQiao-Wen; YEGao-Xiang

    2004-01-01

    By means of the Monte Carlo simulation, a fractal growth model is introduced to describe diffusion-limited aggregation (DLA) under rotation. Patterns which are different from the classical DLA model are observed and the fractal dimension of such clusters is calculated. It is found that the pattern of the clusters and their fractal dimension depend strongly on the rotation velocity of the diffusing particle. Our results indicate the transition from fractal to non-fractal behavior of growing cluster with increasing rotation velocity, i.e. for small enough angular velocity ω; thefractal dimension decreases with increasing ω;, but then, with increasing rotation velocity, the fractal dimension increases and the cluster becomes compact and tends to non-fractal.

  1. Fractal Aggregation Under Rotation

    Institute of Scientific and Technical Information of China (English)

    WU Feng-Min; WU Li-Li; LU Hang-Jun; LI Qiao-Wen; YE Gao-Xiang

    2004-01-01

    By means of the Monte Carlo simulation, a fractal growth model is introduced to describe diffusion-limited aggregation (DLA) under rotation. Patterns which are different from the classical DLA model are observed and the fractal dimension of such clusters is calculated. It is found that the pattern of the clusters and their fractal dimension depend strongly on the rotation velocity of the diffusing particle. Our results indicate the transition from fractal to non-fractal behavior of growing cluster with increasing rotation velocity, i.e. for small enough angular velocity ω the fractal dimension decreases with increasing ω, but then, with increasing rotation velocity, the fractal dimension increases and the cluster becomes compact and tends to non-fractal.

  2. Platelet aggregation following trauma

    DEFF Research Database (Denmark)

    Windeløv, Nis A; Sørensen, Anne M; Perner, Anders;

    2014-01-01

    We aimed to elucidate platelet function in trauma patients, as it is pivotal for hemostasis yet remains scarcely investigated in this population. We conducted a prospective observational study of platelet aggregation capacity in 213 adult trauma patients on admission to an emergency department (ED......). Inclusion criteria were trauma team activation and arterial cannula insertion on arrival. Blood samples were analyzed by multiple electrode aggregometry initiated by thrombin receptor agonist peptide 6 (TRAP) or collagen using a Multiplate device. Blood was sampled median 65 min after injury; median injury...... severity score (ISS) was 17; 14 (7%) patients received 10 or more units of red blood cells in the ED (massive transfusion); 24 (11%) patients died within 28 days of trauma: 17 due to cerebral injuries, four due to exsanguination, and three from other causes. No significant association was found between...

  3. Emergence of Soft Communities from Geometric Preferential Attachment

    CERN Document Server

    Zuev, Konstantin; Bianconi, Ginestra; Krioukov, Dmitri

    2015-01-01

    All real networks are different, but many have some structural properties in common. There seems to be no consensus on what the most common properties are, but scale-free degree distributions, strong clustering, and community structure are frequently mentioned without question. Surprisingly, there exists no simple generative mechanism explaining all the three properties at once in growing networks. Here we show how latent network geometry coupled with preferential attachment of nodes to this geometry fills this gap. We call this mechanism geometric preferential attachment (GPA), and validate it against the Internet. GPA gives rise to soft communities that provide a different perspective on the community structure in networks. The connections between GPA and cosmological models, including inflation, are also discussed.

  4. Emergence of soft communities from geometric preferential attachment.

    Science.gov (United States)

    Zuev, Konstantin; Boguñá, Marián; Bianconi, Ginestra; Krioukov, Dmitri

    2015-04-29

    All real networks are different, but many have some structural properties in common. There seems to be no consensus on what the most common properties are, but scale-free degree distributions, strong clustering, and community structure are frequently mentioned without question. Surprisingly, there exists no simple generative mechanism explaining all the three properties at once in growing networks. Here we show how latent network geometry coupled with preferential attachment of nodes to this geometry fills this gap. We call this mechanism geometric preferential attachment (GPA), and validate it against the Internet. GPA gives rise to soft communities that provide a different perspective on the community structure in networks. The connections between GPA and cosmological models, including inflation, are also discussed.

  5. PREFERENTIAL SPUTTERING OF Cu76Ni15Sn9

    Institute of Scientific and Technical Information of China (English)

    王震遐; 王传珊; 等

    1995-01-01

    Using collection film technique combined with Auger electron spectroscopy is analysis,the preferential sputtering of the ternary alloy Cu76Ni15Sn9 bombarded with 27keV Ar+ at normal incidence is studied.After bombardment,the target surface is examined with SEM,and the surface composition of different topographical feature areas is measured with electron probe micro-analyser(EPMA),The experiment results show that Cu atoms are preferentially ejected compared with Ni atoms,and Sn atoms come third within the ejection angle range from 0°to 60°.The results are discussed from the viewpoint of sputtering from a very rough surface.

  6. Link prediction based on local information considering preferential attachment

    Science.gov (United States)

    Zeng, Shan

    2016-02-01

    Link prediction in complex networks has attracted much attention in many fields. In this paper, a common neighbors plus preferential attachment index is presented to estimate the likelihood of the existence of a link between two nodes based on local information of the nearest neighbors. Numerical experiments on six real networks demonstrated the high effectiveness and efficiency of the new index compared with five well-known and widely accepted indices: the common neighbors, resource allocation index, preferential attachment index, local path index and Katz index. The new index provides competitively accurate prediction with local path index and Katz index while has less computational complexity and is more accurate than the other two indices.

  7. Innovation and Nested Preferential Growth in Chess Playing Behavior

    CERN Document Server

    Perotti, Juan I; Schaigorodsky, Ana L; Billoni, Orlando V

    2013-01-01

    We study innovation in chess by analyzing how different move sequences are played at the population level. It is found that the probability of exploring a new or innovative move decreases as a power law with the frequency in which the preceding move sequence is played. Chess players also exploit already known move sequences according to their frequencies, following a preferential growth mechanism. Furthermore, innovation in chess exhibits Heaps' law suggesting similarities with the process of vocabulary growth. We propose a robust generative mechanism based on nested Yule-Simon preferential growth processes that reproduces the empirical observations. These results, supporting the self-similar nature of innovations in chess, are important in the context of decision making in a competitive scenario.

  8. Preferential growth in FeCoV/Ti:N multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Clemens, D.; Senthil Kumar, M.; Boeni, P.; Horisberger, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    The preferential growth in Fe{sub 0.50}Co{sub 0.48}V{sub 0.02}/Ti:N multilayers was studied by X-ray diffraction. X-ray specular reflectometry and subsequent simulation of the spectra was used to extract information about the thickness and interface roughness of individual layers. The investigation gives structural information about the material combination and its potential for the use of neutron polarizers. (author) 2 figs., 1 tab., 2 refs.

  9. Preferential Trade Agreements and Welfare: General Equilibrium Analysis

    OpenAIRE

    Juyoung Cheong; Shino Takayama; Terence Yeo

    2013-01-01

    This paper studies the welfare effects of a preferential trade agreement (PTA) within a general equilibrium framework following Eaton and Kortum (2002) and conducts a comparative statics analysis of the equilibrium. The paper provides a closed-form analysis with no assumption of balanced trade and analyzes how a PTA affects the price level, trade flows, and welfare of both member and nonmember countries. We show that a PTA decreases the price level of not only member but also nonmember countr...

  10. Cascades with coupled map lattices in preferential attachment community networks

    Institute of Scientific and Technical Information of China (English)

    Cui Di; Gao Zi-You; Zhao Xiao-Mei

    2008-01-01

    In this paper,cascading failure is studied by coupled map lattice (CML) methods in preferential attachment community networks.It is found that external perturbation R is increasing with modularity Q growing by simulation.In particular,the large modularity Q can hold off the cascading failure dynamic process in community networks.Furthermore,different attack strategies also greatly affect the cascading failure dynamic process. It is particularly significant to control cascading failure process in real community networks.

  11. Network Evolution by Relevance and Importance Preferential Attachment

    CERN Document Server

    Zhang, Weituo

    2014-01-01

    Relevance and importance are the main factors when humans build network connections. We propose an evolutionary network model based on preferential attachment(PA) considering these factors. We analyze and compute several important features of the network class generated by this algorithm including scale free degree distribution, high clustering coefficient, small world property and core-periphery structure. We then compare this model with other network models and empirical data such as inter-city road transportation and air traffic networks.

  12. Diagnostic Features of Emotional Expressions Are Processed Preferentially

    OpenAIRE

    Elisa Scheller; Christian Büchel; Matthias Gamer

    2012-01-01

    Diagnostic features of emotional expressions are differentially distributed across the face. The current study examined whether these diagnostic features are preferentially attended to even when they are irrelevant for the task at hand or when faces appear at different locations in the visual field. To this aim, fearful, happy and neutral faces were presented to healthy individuals in two experiments while measuring eye movements. In Experiment 1, participants had to accomplish an emotion cla...

  13. Dye staining and excavation of a lateral preferential flow network

    OpenAIRE

    Anderson, A.E.; Weiler, M.; Alila, Y.; R. O. Hudson

    2008-01-01

    International audience Preferential flow features have been found to be important for runoff generation, solute transport, and slope stability in many areas around the world. Although many studies have identified the particular characteristics of individual features and measured the runoff generation and solute transport within hillslopes, no studies have determined how individual features are hydraulically connected at a hillslope scale. In this study, we used dye staining and excavation ...

  14. Adult motor axons preferentially reinnervate predegenerated muscle nerve

    OpenAIRE

    M. Abdullah; O'Daly, A.; A Vyas; Rohde, C.; Brushart, T.M.

    2013-01-01

    Preferential motor reinnervation (PMR) is the tendency for motor axons regenerating after repair of mixed nerve to reinnervate muscle nerve and/or muscle rather than cutaneous nerve or skin. PMR may occur in response to the peripheral nerve pathway alone in juvenile rats (Brushart, 1993; Redett et al., 2005), yet the ability to identify and respond to specific pathway markers is reportedly lost in adults (Uschold et al., 2007). The experiments reported here evaluate the relative roles of path...

  15. Significance of tree roots for preferential infiltration in stagnic soils

    OpenAIRE

    Lange, B; Lüescher, P.; P. F. Germann

    2009-01-01

    It is generally recognized that roots have an effect on infiltration. In this study we analysed the relation between root length distributions from Norway spruce (Picea abies (L.) Karst), silver fir (Abies alba Miller), European beech (Fagus sylvatica L.) and preferential infiltration in stagnic soils in the northern Pre-Alps in Switzerland. We conducted irrigation experiments (1 m2) and recorded water content var...

  16. Significance of tree roots for preferential infiltration in stagnic soils

    Directory of Open Access Journals (Sweden)

    B. Lange

    2008-08-01

    Full Text Available It is generally believed that roots have an effect on infiltration. In this study we analysed the influence of tree roots from Norway spruce (Picea abies (L. Karst, silver fir (Abies alba Miller and European beech (Fagus sylvatica L. on preferential infiltration in stagnic soils in the northern pre-Alps in Switzerland. We conducted irrigation experiments (1 m2 and recorded water content variations with time domain reflectrometry (TDR. A rivulet approach was applied to characterise preferential infiltration. Roots were sampled down to a depth of 0.5 to 1 m at the same position where the TDR-probes had been inserted and digitally measured. The basic properties of preferential infiltration, film thickness of mobile water and the contact length between soil and mobile water in the horizontal plane are closely related to fine root densities. An increase in root density resulted in an increase in contact length, but a decrease in film thickness. We modelled water content waves based on fine root densities and identified a range of root densities that lead to a maximum volume flux density and infiltration capacity. These findings provide convincing evidence that tree roots improve soil structure and thus infiltration.

  17. Controls of macropore network characteristics on preferential solute transport

    Directory of Open Access Journals (Sweden)

    M. Larsbo

    2014-08-01

    Full Text Available In this study we examined the relationships between macropore network characteristics, hydraulic properties and state variables and measures of preferential transport in undisturbed columns sampled from four agricultural topsoils of contrasting texture and structure. Macropore network characteristics were computed from 3-dimensional X-ray tomography images of the soil pore system. Non-reactive solute transport experiments were carried out at five steady-state water flow rates from 2 to 12 mm h−1. The degree of preferential transport was evaluated by the normalised 5% solute arrival time and the apparent dispersivity calculated from the resulting breakthrough curves. Near-saturated hydraulic conductivities were measured on the same samples using a tension disk infiltrometer placed on top of the columns. Results showed that many of the macropore network characteristics were inter-correlated. For example, large macroporosities were associated with larger specific macropore surface areas and better local connectivity of the macropore network. Generally, an increased flow rate resulted in earlier solute breakthrough and a shifting of the peak concentration towards smaller drained volumes. Columns with smaller macroporosities, poorer local connectivity of the macropore network and smaller near-saturated hydraulic conductivities exhibited a greater degree of preferential transport. This can be explained by the fact that, with only two exceptions, global (i.e. sample-scale continuity of the macropore network was still preserved at low macroporosities. Thus, for any given flow rate pores of larger diameter were actively conducting solute in soils of smaller near-saturated hydraulic conductivity. With less time for equilibration between the macropores and the surrounding matrix the transport became more preferential. Conversely, the large specific macropore surface area and well-connected macropore networks associated with columns with large

  18. Logical Constraints on Judgement Aggregation

    NARCIS (Netherlands)

    Hees, Martin van; Pauly, Marc

    2006-01-01

    Logical puzzles like the doctrinal paradox raise the problem of how to aggregate individual judgements into a collective judgement, or alternatively, how to merge collectively inconsistent knowledge bases. In this paper, we view judgement aggregation as a function on propositional logic valuations,

  19. Exciton dynamics in molecular aggregates

    NARCIS (Netherlands)

    Augulis, R.; Pugžlys, A.; Loosdrecht, P.H.M. van; Pugzlys, A

    2006-01-01

    The fundamental aspects of exciton dynamics in double-wall cylindrical aggregates of cyanine dyes are studied by means of frequency resolved femtosecond pump-probe spectroscopy. The collective excitations of the aggregates, resulting from intermolecular dipole-dipole interactions have the characteri

  20. Aggregate resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Gessel, S.F. van; Veldkamp, J.G.

    2005-01-01

    We have built a 3D lithological model of the Netherlands, for the purpose of mapping on-land aggregate resources down to 50 m below the surface. The model consists of voxel cells (1000 · 1000 · 1 m), with lithological composition and aggregate content estimates as primary attributes. These attribute

  1. Study of β-amyloid adsorption and aggregation on graphite by STM and AFM

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The scanning tunneling microscopy (STM) and the atomic force microscopy (AFM) have been applied to the direct study of the adsorption and aggregation of β-amyloid(1-42)(Aβ42) on the hydrophobic graphite surface. It was found that Aβ42 were preferentially adsorbed on graphite defects such as the edges. Aβ42 peptides self-assembled into intermediate protofibrils, which in turn self-associated to form fibrils. Usually, two or more fibrils intertwined to form the helical structure. These results will provide an important clue to studying the aggregation process of β-amyloid.

  2. Optical monitoring of particle aggregates

    Institute of Scientific and Technical Information of China (English)

    John Gregory

    2009-01-01

    Methods for monitoring particle aggregation are briefly reviewed. Most of these techniques are based on some form of light scattering and may be greatly dependent on the optical properties of aggregates, which are not generally known. As fractal aggregates grow larger their density can become very low and this has important practical consequences for light scattering. For instance, the scattering coefficient may be much less than for solid objects, which means that the aggregates can appear much smaller than their actual size by a light transmission method. Also, for low-density objects, a high proportion of the scattered light energy is within a small angle of the incident beam, which may also be relevant for measurements with aggregates.Using the 'turbidity fluctuation' technique as an example, it is shown how the apparent size of hydroxide flocs depends mainly on the included impurity particles, rather than the hydroxide precipitate itself. Results using clay suspensions with hydrolyzing coagulants and under are discussed.

  3. Molecular aggregation of humic substances

    Science.gov (United States)

    Wershaw, R. L.

    1999-01-01

    Humic substances (HS) form molecular aggregates in solution and on mineral surfaces. Elucidation of the mechanism of formation of these aggregates is important for an understanding of the interactions of HS in soils arid natural waters. The HS are formed mainly by enzymatic depolymerization and oxidation of plant biopolymers. These reactions transform the aromatic and lipid plant components into amphiphilic molecules, that is, molecules that consist of separate hydrophobic (nonpolar) and hydrophilic (polar) parts. The nonpolar parts of the molecules are composed of relatively unaltered segments of plant polymers and the polar parts of carboxylic acid groups. These amphiphiles form membrane-like aggregates on mineral surfaces and micelle-like aggregates in solution. The exterior surfaces of these aggregates are hydrophilic, and the interiors constitute separate hydrophobic liquid-like phases.

  4. DRAG ON SUBMICRON NANOPARTICLE AGGREGATES

    Institute of Scientific and Technical Information of China (English)

    F.; Einar; Kruis

    2005-01-01

    A new procedure was developed for estimating the effective collision diameter of an aggregate composed of primary particles of any size. The coagulation coefficient of two oppositely charged particles was measured experimentally and compared with classic Fuchs theory, including a new method to account for particle non-sphericity. A second set of experiments were performed on well-defined nanoparticle aggregates at different stages of sintering, i.e. from the aggregate to the fully sintered stage. Here, electrical mobility was used to characterize the particle drag. The aggregates are being built from two different size-fractionated nanoparticle aerosols, the non-aggregated particles are discarded by an electrofilter and then they are passed through a furnace at concentrations low enough not to induce coagulation.

  5. Immunogenicity of Therapeutic Protein Aggregates.

    Science.gov (United States)

    Moussa, Ehab M; Panchal, Jainik P; Moorthy, Balakrishnan S; Blum, Janice S; Joubert, Marisa K; Narhi, Linda O; Topp, Elizabeth M

    2016-02-01

    Therapeutic proteins have a propensity for aggregation during manufacturing, shipping, and storage. The presence of aggregates in protein drug products can induce adverse immune responses in patients that may affect safety and efficacy, and so it is of concern to both manufacturers and regulatory agencies. In this vein, there is a lack of understanding of the physicochemical determinants of immunological responses and a lack of standardized analytical methods to survey the molecular properties of aggregates associated with immune activation. In this review, we provide an overview of the basic immune mechanisms in the context of interactions with protein aggregates. We then critically examine the literature with emphasis on the underlying immune mechanisms as they relate to aggregate properties. Finally, we highlight the gaps in our current understanding of this issue and offer recommendations for future research. PMID:26869409

  6. Dye Aggregation in Ink Jet

    Institute of Scientific and Technical Information of China (English)

    Thomas Paul; Sarfraz Hussain

    2004-01-01

    Dye aggregation has long been recognised as a key factor in performance, and this is no less so in ink jet applications. The aggregation state was shown to be important in many different areas ranging from the use of dyes in photodynamic therapies all the way to colorants for dying of fabrics. Therefore different methods to investigate dye association qualitatively and quantitatively were developed. A simple procedure to study aggregation could be a useful tool to characterise dyes for ink jet printing. It is critically reviewed the methods used to study dye aggregation, and discussed some of the main conclusions. This will be illustrated by examples of ink jet dye aggregation and its study in aqueous and ink systems. The results are used to correlate the solution behaviour of dyes with their print performance.

  7. Orthogonal flexible Rydberg aggregates

    CERN Document Server

    Leonhardt, K; Rost, J M

    2015-01-01

    We study the link between atomic motion and exciton transport in flexible Rydberg aggregates, assemblies of highly excited light alkali atoms, for which motion due to dipole-dipole interaction becomes relevant. In two one-dimensional atom chains crossing at a right angle adiabatic exciton transport is affected by a conical intersection of excitonic energy surfaces, which induces controllable non-adiabatic effects. A joint exciton/motion pulse that is initially governed by a single energy surface is coherently split into two modes after crossing the intersection. The modes induce strongly different atomic motion, leading to clear signatures of non-adiabatic effects in atomic density profiles. We have shown how this scenario can be exploited as an exciton switch, controlling direction and coherence properties of the joint pulse on the second of the chains [K.~Leonhardt {\\it et al.}, Phys.~Rev.~Lett. {\\bf 113} 223001 (2014)]. In this article we discuss the underlying complex dynamics in detail, characterise the ...

  8. Perspectives on Preference Aggregation.

    Science.gov (United States)

    Regenwetter, Michel

    2009-07-01

    For centuries, the mathematical aggregation of preferences by groups, organizations, or society itself has received keen interdisciplinary attention. Extensive theoretical work in economics and political science throughout the second half of the 20th century has highlighted the idea that competing notions of rational social choice intrinsically contradict each other. This has led some researchers to consider coherent democratic decision making to be a mathematical impossibility. Recent empirical work in psychology qualifies that view. This nontechnical review sketches a quantitative research paradigm for the behavioral investigation of mathematical social choice rules on real ballots, experimental choices, or attitudinal survey data. The article poses a series of open questions. Some classical work sometimes makes assumptions about voter preferences that are descriptively invalid. Do such technical assumptions lead the theory astray? How can empirical work inform the formulation of meaningful theoretical primitives? Classical "impossibility results" leverage the fact that certain desirable mathematical properties logically cannot hold in all conceivable electorates. Do these properties nonetheless hold true in empirical distributions of preferences? Will future behavioral analyses continue to contradict the expectations of established theory? Under what conditions do competing consensus methods yield identical outcomes and why do they do so? PMID:26158988

  9. Flow-aggregation Accelerating Strategy for TCP Traffic

    Directory of Open Access Journals (Sweden)

    Xiaoguo Zhang

    2014-06-01

    Full Text Available A great number of researches on network flow characteristics show a large proportion of the network flows are single-packet flows. However, almost all existing flow termination strategies have no optimization for single-packet flows, so the efficiency of flow-aggregation is lower. Based on in-depth study of flow characteristics and TCP protocol specifications, we find the packet status, packet arrival interval and SYN packet size can identify single-packet flows accurately, and then propose a flow-aggregation accelerating strategy for TCP traffic that aims to quickly identify single-packet flows. We build efficiency model and accuracy model to compare our strategy performance with others and make a lot of experiments on the traces collected from a main channel in the CERNET during the latest five years. The results prove our strategy can greatly improve the efficiency of flow-aggregation at the cost of very little loss of accuracy

  10. Inflation Dynamics and the Cost Channel of Monetary Transmission

    NARCIS (Netherlands)

    I. Chowdhury; M. Hoffmann; A. Schabert

    2006-01-01

    Evidence from vector autoregressions indicates that the impact of interest rate shocks on macroeconomic aggregates can substantially be affected by the so-called cost channel of monetary transmission. In this paper, we apply a structural approach to examine the relevance of the cost channel for infl

  11. Field investigation of preferential fissure flow paths with hydrochemical analysis of small-scale sprinkling experiments

    NARCIS (Netherlands)

    Krzeminska, D.M.; Bogaard, T.A.; Debieche, T.-H.; Cervi, F.; Marc, V.; Malet, J.-P.

    2014-01-01

    The unsaturated zone largely controls groundwater recharge by buffering precipitation while at the same time providing preferential flow paths for infiltration. The importance of preferential flow on landslide hydrology is recognised in the literature; however, its monitoring and quantification rema

  12. Soil organic carbon, macropore networks and preferential transport

    Science.gov (United States)

    Larsbo, Mats; Koestel, John; Kätterer, Thomas; Jarvis, Nick

    2016-04-01

    Agricultural management practices such as tillage, crop rotations, residue management and fertilization can have a strong influence on soil organic carbon (SOC) stocks. An increase in SOC content will generally improve soil structure, which in turn determines the solute transport pathways through the soil. The aim of this study was to quantify the architecture of macropore networks in undisturbed soil columns (15 cm high, 12.7 cm diameter) sampled along a transect with natural variations in SOC using X-ray tomography and to relate the network characteristics to the degree of preferential transport in the columns. Two tracer experiments were carried out at constant irrigation rates of 2 and 5 mm h-1. We used the normalised 5% arrival time which reflects the tendency for early arrival of the solutes as a measure of the degree of preferential transport. The soil macropore networks were analysed in cylindrical sub-volumes (8 cm high, 10 cm diameter) located centrally within the soil columns. These sub-volumes were considered unaffected by sampling artefacts. Analyses were also carried out the for whole sample volumes to enable comparisons with the results from the transport experiments. Image processing and analysis were carried out in ImageJ and R. The same grey value threshold was applied to all images after harmonisation of grey values using the PVC column walls and the air outside the columns. This approach resulted in a satisfactory separation between the pore space and the surrounding soil matrix and organic matter. The SOC content along the transect, which varied from 4.2 to 15% , was correlated to all measures of the pore network for the sub-volumes except for the connectivity probability. Columns with high SOC content were associated with large macroporosities (both total and connected), large specific surface areas, large fractal dimensions and small mean pore thicknesses. The SOC content for whole sample volumes was positively correlated to 5% arrival times

  13. The influence of anisotropy on preferential flow in landslides

    Science.gov (United States)

    Cristiano, Elena; Barontini, Stefano; Bogaard, Thom A.; Shao, Wei

    2015-04-01

    Infiltration is one of the most important landslides triggering mechanisms and it is controlled by the hydraulic characteristics of the soil, which depends on the degree of saturation, the existence of preferential flow paths and by anisotropy. Many soils, indeed, exhibit a certain degree of anisotropy due to the stratification associated with soil forming process. Recently, various authors investigated the effect of rainfall in layered soils and its effect on rainfall triggered landslides by means of experimental, conceptual, numerical and theoretical approaches. However, the combined effect of anisotropy and preferential flow on infiltration process and related to rainfall induced landslides has, according to the authors best knowledge, not been studied yet. Aiming at better understanding the soil hydrological processes which take place during an infiltration process, the stability of a synthetic hill slope is numerically investigated. The geometry we considered for the model is a slope with two different layers: the upper soil layer consists of sandy loam, while the lower soil layer is made out of clay. The geometry was studied using both a single permeability and a dual permeability model. In the first case the hydraulic conductivity at saturation was considered isotropic, equal in all directions. Then the vertical component of the hydraulic conductivity tensor at saturation was reduced, while in the third scenario the horizontal component was reduced. In this way the anisotropy effects on both the principal directions were studied. In the dual permeability model, the influence of the anisotropy was considered only in the preferential flow domain, and the hydraulic conductivity at saturation of the soil matrix domain was defined as being isotropic. In order to evaluate also the effects of rainfall intensity on the slope, two different rainfall events were studied: a low intensity rainfall with a long time duration (2 mmh-1,150 h) and an high intensity rainfall

  14. Vadose Zone Sampling Methods for Detection of Preferential Pesticides Transport

    Science.gov (United States)

    Peranginangin, N.; Richards, B. K.; Steenhuis, T. S.

    2003-12-01

    Leaching of agricultural applied chemicals through the vadose zone is a major cause for the occurrence of agrichemicals in groundwater. Accurate soil water sampling methods are needed to ensure meaningful monitoring results, especially for soils that have significant preferential flow paths. The purpose of this study was to assess the capability and the effectiveness of various soil water sampling methods in detecting preferential transport of pesticides in a strongly-structured silty clay loam (Hudson series) soil. Soil water sampling devices tested were wick pan and gravity pan lysimeters, tile lines, porous ceramic cups, and pipe lysimeters; all installed at 45 to105 cm depth below the ground surface. A reasonable worse-case scenario was tested by applying a simulated rain storm soon after pesticides were sprayed at agronomic rates. Herbicides atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) and 2,4-D (2,4-dichloro-phenoxyacetic acid) were chosen as model compounds. Chloride (KCl) tracer was used to determine spatial and temporal distribution of non-reactive solute and water as well as a basis for determining the retardation in pesticides movement. Results show that observed pesticide mobility was much greater than would be predicted by uniform flow. Under relatively high soil moisture conditions, gravity and wick pan lysimeters had comparably good collection efficiencies, whereas the wick samplers had an advantage over gravity driven sampler when the soil moisture content was below field capacity. Pipe lysimeters had breakthrough patterns that were similar to pan samplers. At small plot scale, tile line samplers tended to underestimate solute concentration because of water dilution around the samplers. The use of porous cup samplers performed poorly because of their sensitivity to local profile characteristics: only by chance can they intercept and sample the preferential flow paths that are critical to transport. Wick sampler had the least

  15. Connecting ecohydrology and hydropedology in desert shrubs: stemflow as a source of preferential flow in soils

    Directory of Open Access Journals (Sweden)

    X.-Y. Li

    2009-03-01

    Full Text Available Ecohydrology and hydropedology are two emerging fields that are interconnected. In this study, we demonstrate stemflow hydrology and preferential water flow along roots in two desert shrubs (H. scoparium and S. psammophila in the south fringe of Mu Us sandy land in North China. Stemflow generation and subsequent movement within soil-root system were investigated during the growing seasons from 2006 to 2008. The results indicated that the amount of stemflow in H. scoparium averaged 3.4% of incident gross rainfall with a range of 2.3–7.0%, and in S. psammophila stemflow averaged 6.3% with a range of 0.2–14.2%. Stemflow was produced from rainfall events more than 1 mm for both shrubs. The average funneling ratio (the ratio of rainfall amount delivered to the base of the tree to the rainfall that would have reached the ground should the tree were not present was 77.8 and 48.7 for H. scoparium and S. psammophila, respectively, indicating that branches and stems were fully contributing to stemflow generation and thereby provided considerable amount of water to deep soil layer. Analysis of rhodamine-B dye distribution under the shrubs showed that stemflow entered the soil preferentially along root channels contributing to deep storage and that the depth of stemflow infiltrated increased with increasing incident rainfall amount. Distribution of soil water content under the shrubs with and without stemflow ascertained that stemflow was conducive to concentrate and store water in deep layers in the soil profiles, creating favorable soil water conditions for plant growth under arid conditions. Accordingly there is a clear linkage between aboveground ecohydrology and belowground hydropedology in the desert shrubs, whereby an increase in stemflow would result in an increase in soil hydrological heterogeneity.

  16. Brands & Channels

    Institute of Scientific and Technical Information of China (English)

    Alice Yang

    2009-01-01

    @@ "Brands" and "Channels" are the two most important things in Ku-Hai Chen's eyes when doing business with Main-land China. Ku-Hai Chen, Executive Director of the International Trade Institute of Taiwan External Trade Development Council (TAITRA), flies frequently between Chinese Taipei and Mainland China, and was in Beijing earlier this month for his seminar.

  17. Experimental Study of Active Path Block in a Multi-Bifurcated Flow by Microbubble Aggregation

    Science.gov (United States)

    Shigehara, Nobuhiko; Demachi, Fumi; Koda, Ren; Mochizuki, Takashi; Masuda, Kohji; Ikeda, Seiichi; Arai, Fumihito; Miyamoto, Yoshitaka; Chiba, Toshio

    2013-07-01

    We previously reported our attempts at the active control of microbubble aggregations using acoustic radiation force, which propels microbubbles and adjusts the size of aggregations. However, because we used simple-shape artificial blood vessels, the behavior of aggregations in a small channel, e.g., the probability to obstruct the bloodstream, and the possibility of embolization, has not been predicted. Thus, we designed and fabricated a multi-bifurcated artificial blood vessel to apply to the production and active control of microbubble aggregations. Then, we introduced two kinds of ultrasound transducers for producing and propelling aggregations. First, we produced aggregations in a flow to measure their size and investigate their variation according to the emission duration of ultrasound. Then, we control the aggregations in an artificial blood vessel to verify their controllability. When ultrasound was stopped, the aggregations flaked off the vessel wall and flowed downstream, were propelled to the desired path, and finally were caught at a narrow path. We verified the same experiment under similar parameters to calculate the probability of realizing a path block. When the flow velocity was 20 mm/s, almost 50% of the aggregations were induced to flow through the desired path and a maximum probability of realizing a path block of 86% was achieved with the formation of aggregations.

  18. Preferential adhesion of leukocytes near bifurcations is endothelium independent.

    Science.gov (United States)

    Tousi, Nazanin; Wang, Bin; Pant, Kapil; Kiani, Mohammad F; Prabhakarpandian, Balabhaskar

    2010-12-01

    Leukocyte-endothelial interactions play central roles in many pathological conditions. However, the in vivo mechanisms responsible for nonuniform spatial distribution of adhering leukocytes to endothelial cells in microvascular networks are not clear. We used a combination of in vitro and in vivo methodologies to explain of this complex phenomenon. A mouse cremaster muscle model was used to study the spatial distribution of leukocyte-endothelial cell interaction in vivo. A PDMS-based synthetic microvascular network (SMN) device was used to study interactions of functionalized microspheres using a receptor-ligand system in a (endothelial) cell-free environment for the in vitro studies. Our in vivo and in vitro findings indicate that both leukocytes in vivo and microspheres in vitro preferentially adhere near bifurcation (within 1-2 diameters from the bifurcation). This adhesion pattern was found to be independent of the diameter of the vessels. These findings support our hypothesis that the fluidic patterns near bifurcations/junctions, and not the presence or cellular aspects of the system (e.g. cell deformation, cell signaling, heterogeneous distribution of adhesion molecules), is the main controlling factor behind the preferential adhesion patterns of leukocytes near bifurcations. PMID:20624406

  19. Innovation and nested preferential growth in chess playing behavior

    Science.gov (United States)

    Perotti, J. I.; Jo, H.-H.; Schaigorodsky, A. L.; Billoni, O. V.

    2013-11-01

    Complexity develops via the incorporation of innovative properties. Chess is one of the most complex strategy games, where expert contenders exercise decision making by imitating old games or introducing innovations. In this work, we study innovation in chess by analyzing how different move sequences are played at the population level. It is found that the probability of exploring a new or innovative move decreases as a power law with the frequency of the preceding move sequence. Chess players also exploit already known move sequences according to their frequencies, following a preferential growth mechanism. Furthermore, innovation in chess exhibits Heaps' law suggesting similarities with the process of vocabulary growth. We propose a robust generative mechanism based on nested Yule-Simon preferential growth processes that reproduces the empirical observations. These results, supporting the self-similar nature of innovations in chess are important in the context of decision making in a competitive scenario, and extend the scope of relevant findings recently discovered regarding the emergence of Zipf's law in chess.

  20. Dependability in Aggregation by Averaging

    CERN Document Server

    Jesus, Paulo; Almeida, Paulo Sérgio

    2010-01-01

    Aggregation is an important building block of modern distributed applications, allowing the determination of meaningful properties (e.g. network size, total storage capacity, average load, majorities, etc.) that are used to direct the execution of the system. However, the majority of the existing aggregation algorithms exhibit relevant dependability issues, when prospecting their use in real application environments. In this paper, we reveal some dependability issues of aggregation algorithms based on iterative averaging techniques, giving some directions to solve them. This class of algorithms is considered robust (when compared to common tree-based approaches), being independent from the used routing topology and providing an aggregation result at all nodes. However, their robustness is strongly challenged and their correctness often compromised, when changing the assumptions of their working environment to more realistic ones. The correctness of this class of algorithms relies on the maintenance of a funda...

  1. Isolation and Aggregation in Economics

    OpenAIRE

    Schlicht, Ekkehart

    1985-01-01

    In explaining economic phenomena, economic analysis concentrates on selected influences and fixes the host of other factors under a ceteris paribus clause. This view, which goes back to Alfred Marshall (1842-1924), is developed in the first part of the book. Aggregation is viewed as a particular application of ceteris paribus analysis - isolation from "structural effects". This leads to an approach, called "closed aggregation", which was introduced by Kenneth May and is also implicit in Keyne...

  2. Channel Power in Multi-Channel Environments

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); B. Skiera (Bernd)

    2004-01-01

    textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key compon

  3. Inventories, oil shocks, and aggregate economic behavior

    Science.gov (United States)

    Herrera, Ana Maria

    This dissertation examines the relationship between oil price shocks and aggregate economic behavior in the U.S. The first chapter addresses the effects of changes in the price of crude oil on the manufacturing sector in VAR regressions and in a structural linear quadratic inventory model. It finds that oil price increases lead to reductions in manufacturing activity while oil price falls are not followed by booms. This asymmetry in the response of the manufacturing activity, the changes in the composition of the demand, and the large variations in sales of key investment and consumption goods favor a multi-channel transmission mechanism. The analysis shows that differences in the response of the various industrial sectors are determined by the cost structure of the industry as well as by the dynamics of the demand, cost and oil shocks. Positive oil price shocks are first transmitted from the transportation equipment industry to sectors such as primary metals products, rubber and plastics and textiles, later affecting the remaining sectors and the aggregates. In the short run inventories act as a buffer however, one and a half years after the shock significant production cuts do take place. Sluggishness in the response of aggregate output can be accounted by the behavior of inventories as well as by the time lags implied in the propagation from one industry to the remaining sectors and the aggregate. The second chapter studies the role of oil prices and monetary policy in accounting for business cycles in an identified VAR framework. It finds that the slowdown in GDP growth that follows an oil shock can not be solely explained by the response of the Fed's monetary policy. An "exogenous" monetary policy that holds the fed funds rate fixed would exert a large expansionary effect. Nevertheless, conditional on this policy, the reduction in economic activity persists and the price level increases leading to a sharp reduction in the short-term interest rate. In addition

  4. Single-Degenerate Type Ia Supernovae Are Preferentially Overluminous

    CERN Document Server

    Fisher, Robert

    2015-01-01

    Recent observational and theoretical progress has favored merging and helium-accreting sub-Chandrasekhar mass white dwarfs in the double-degenerate and the double-detonation channels, respectively, as the most promising progenitors of normal Type Ia supernovae (SNe Ia). Thus the fate of rapidly-accreting Chandrasekhar mass white dwarfs in the single-degenerate channel remains more mysterious then ever. In this paper, we clarify the nature of ignition in Chandrasekhar-mass single-degenerate SNe Ia by analytically deriving the existence of a characteristic length scale which establishes a transition from central ignitions to buoyancy-driven ignitions. Using this criterion, combined with data from three-dimensional simulations of convection and ignition, we demonstrate that the overwhelming majority of ignition events within Chandrasekhar-mass white dwarfs in the single-degenerate channel are buoyancy-driven, and consequently lack a vigorous deflagration phase. We thus infer that single-degenerate SNe Ia are gen...

  5. Affecting factors of preferential flow in the forest of the Three Gorges area, Yangtze River

    Institute of Scientific and Technical Information of China (English)

    CHENG Jinhua; ZHANG Hongjiang; HE Fan; QI Shenglin; SUN Yanhong; ZHANG Youyan; SHI Yuhu

    2007-01-01

    In order to study the factors affecting preferential flow,a 2.9 m-long,2.6 m-deep soil profile was dug in the Quxi watershed,Yangtze River.To analyze the influence of rainfall on preferential flow,the preferential flow process was observed when the rainfalls were recorded.Soil physical and infiltration characteristics were also measured to study their effect on preferential flow.The results showed that the rainfall amount that could cause preferential flow was over 26 mm.There are four types of rainfall in the Three Gorges area,namely gradually dropping rain,even rain,sudden rain and peak rain.Preferential flow process was found to be relevant to the rainfall process.It was determined that with different rainfall types,preferential flow appeared at different times,occurring first in peak rain,followed by sudden rain,gradually dropping rain,and then even rain.Preferential flow would appear when the rainfall intensity was over 0.075 mm/min.In the studied area,the coarse soil particles increased with the soil depth,and for the deeper soil layer,the coarse particles promote the formation of preferential flow.Preferential flow accelerates the steady infiltration rate in the 83-110 cm soil horizon,and the quickly moving water in this horizon also enhanced the further formation and development of preferential flow.

  6. Granger causality stock market networks: Temporal proximity and preferential attachment

    Science.gov (United States)

    Výrost, Tomáš; Lyócsa, Štefan; Baumöhl, Eduard

    2015-06-01

    The structure of return spillovers is examined by constructing Granger causality networks using daily closing prices of 20 developed markets from 2nd January 2006 to 31st December 2013. The data is properly aligned to take into account non-synchronous trading effects. The study of the resulting networks of over 94 sub-samples revealed three significant findings. First, after the recent financial crisis the impact of the US stock market has declined. Second, spatial probit models confirmed the role of the temporal proximity between market closing times for return spillovers, i.e. the time distance between national stock markets matters. Third, a preferential attachment between stock markets exists, i.e. the probability of the presence of spillover effects between any given two markets increases with their degree of connectedness to others.

  7. From Idealism to Realism? EU Preferential Trade Agreement Policy

    Directory of Open Access Journals (Sweden)

    Maria Garcia

    2013-10-01

    Full Text Available This article examines how the EU’s ‘conflicted power’ in trade has played out within its preferential trade agreement (PTA strategies with third parties. It does this by providing an overview of how approaches to the EU’s external trade policies have evolved over time, especially since the end of the Cold War. Tracing changes in discourse in the EU’s consolidated trade policy demonstrates how the policy objectives have evolved from what could be characterised as a soft and even normative power to a much more realist one, attempting to safeguard its position in the international economic order. Notwithstanding these changes, explained by a combination of international context and ideational preferences, an underlying overall continuity has remained in terms of the main economic interests to be realised through trade policy, which presents a portrait of the EU as a rational and realist (if sometimes conflicted actor in the global economy.

  8. Efficient target control of complex networks based on preferential matching

    CERN Document Server

    Zhang, Xizhe; Lv, Tianyang

    2016-01-01

    Controlling a complex network towards a desire state is of great importance in many applications. Existing works present an approximate algorithm to find the driver nodes used to control partial nodes of the network. However, the driver nodes obtained by this algorithm depend on the matching order of nodes and cannot get the optimum results. Here we present a novel algorithm to find the driver nodes for target control based on preferential matching. The algorithm elaborately arrange the matching order of nodes in order to minimize the size of the driver nodes set. The results on both synthetic and real networks indicate that the performance of proposed algorithm are better than the previous one. The algorithm may have various application in controlling complex networks.

  9. Preferential dissolution behaviour in Ni–Cr dental cast alloy

    Indian Academy of Sciences (India)

    Viswanathan S Saji; Han Cheol Choe

    2010-08-01

    A Ni–Cr–Mo dental alloy was fabricated by three different casting methods, viz. centrifugal casting, high frequency induction casting and vacuum pressure casting. The dependence of cast microstructure on the electrochemical corrosion behaviour was investigated using potentiodynamic cyclic and potentiostatic polarization techniques, impedance spectroscopy and scanning electron microscopy. The experimental results were compared and discussed with those obtained for a Co–Cr–Mo counterpart. The results of the study showed that the variation in casting morphologies with casting methods has only marginal influence in the overall corrosion resistance of Ni–Cr and Co–Cr dental alloys. There was severe preferential dissolution of Ni rich, Cr and Mo depleted zones from the Ni–Cr–Mo alloy. The overall corrosion resistance property of the Co–Cr base alloy was better than that of the Ni–Cr base alloy.

  10. Growth mechanism of a preferentially oriented mordenite membrane

    Institute of Scientific and Technical Information of China (English)

    LI Gang; LIN Rui-sen; KIKUCHI Eiichi; MATSUKATA Masahiko

    2005-01-01

    A preferentially oriented mordenite membrane was successfully prepared on a seeded porous α-alumina support.Characterization results of XRD (X-ray diffractometer) and FE-SEM (field emission scanning electron microscope) revealed that evolutionary selection might predominantly contribute to the formation of the sharply oriented mordenite membrane. The necessary conditions under which evolutionary selection occurs are: (a) the number density of nuclei on the support surface should be high enough at the early stage; (b) the crystals should grow fastest along one direction; and (c) the zeolite layer should proceed via the successive growth of the crystals nucleated on the support surface instead of the accumulation of the crystals formed in the bulk solution.

  11. Cambogin is preferentially cytotoxic to cells expressing PDGFR.

    Directory of Open Access Journals (Sweden)

    Ze Tian

    Full Text Available Platelet-derived growth factor receptors (PDGFRs have been implicated in a wide array of human malignancies, including medulloblastoma (MB, the most common brain tumor of childhood. Although significant progress in MB biology and therapeutics has been achieved during the past decades, MB remains a horrible challenge to the physicians and researchers. Therefore, novel inhibitors targeting PDGFR signaling pathway may offer great promise for the treatment of MB. In the present study, we investigated the cytotoxicity and mechanisms of cambogin in Daoy MB cells. Our results show that cambogin triggers significant S phase cell cycle arrest and apoptosis via down regulation of cyclin A and E, and activation of caspases. More importantly, further mechanistic studies demonstrated that cambogin inhibits PDGFR signaling in Daoy and genetically defined mouse embryo fibroblast (MEF cell lines. These results suggest that cambogin is preferentially cytotoxic to cells expressing PDGFR. Our findings may provide a novel approach by targeting PDGFR signaling against MB.

  12. Choosy Cannibals Preferentially Consume Siblings with Relatively Low Fitness Prospects.

    Science.gov (United States)

    Dugas, Matthew B; McCormack, Larkin; Gadau, Alice; Martin, Ryan A

    2016-07-01

    When an individual can selfishly cannibalize a relative or altruistically set it free, the benefits of altruism will be positively associated with the relative's fitness prospects (the benefits it receives from altruism). We tested the prediction that altruism should be preferentially directed toward high-quality relatives using larvae of the New Mexican spadefoot toad (Spea multiplicata), a species in which tadpoles plastically express omnivore and carnivore ecomorphs. In a no-choice design, we presented carnivores with sibling or nonsibling omnivores varying in developmental stage, which is positively associated with survival in this toad's ephemeral larval environment. There was a significant interaction between relatedness and developmental stage on the probability of cannibalism: carnivores were overall more likely to cannibalize less developed omnivores, but this effect was exaggerated when the potential victim was a sibling. This evidence that altruists favor relatives with high fitness prospects highlights the numerous factors shaping altruism's payoffs. PMID:27322127

  13. Predicting Alcohol, Cigarette, and Marijuana Use From Preferential Music Consumption.

    Science.gov (United States)

    Oberle, Crystal D; Garcia, Javier A

    2015-01-01

    This study investigated whether use of alcohol, cigarettes, and marijuana may be predicted from preferential consumption of particular music genres. Undergraduates (257 women and 78 men) completed a questionnaire assessing these variables. Partial correlation analyses, controlling for sensation-seeking tendencies and behaviors, revealed that listening to conventional music (pop, country, and religious genres) was negatively correlated with cigarette smoking (p=.001) and marijuana use (pmusic (rap or hip-hop and soul or funk genres) was positively correlated with marijuana use (p=.004). The only significant predictor of alcohol use was country music, with which it was positively correlated (p=.04). This research suggests an especially harmful influence of energetic music on marijuana use.

  14. Preferential partner selection in an evolutionary study of prisoner's dilemma

    CERN Document Server

    Ashlock, D; Stanley, E A; Tesfatsion, L; Ashlock, Dan; Smucker, Mark D; Stanley, E Ann; Tesfatsion, Leigh

    1994-01-01

    Partner selection is an important process in many social interactions, permitting individuals to decrease the risks associated with cooperation. In large populations, defectors may escape punishment by roving from partner to partner, but defectors in smaller populations risk social isolation. We investigate these possibilities for an evolutionary prisoner's dilemma in which agents use expected payoffs to choose and refuse partners. In comparison to random or round-robin partner matching, we find that the average payoffs attained with preferential partner selection tend to be more narrowly confined to a few isolated payoff regions. Most ecologies evolve to essentially full cooperative behavior, but when agents are intolerant of defections, or when the costs of refusal and social isolation are small, we also see the emergence of wallflower ecologies in which all agents are socially isolated. In between these two extremes, we see the emergence of ecologies whose agents tend to engage in a small number of defecti...

  15. Complex networks as an emerging property of hierarchical preferential attachment.

    Science.gov (United States)

    Hébert-Dufresne, Laurent; Laurence, Edward; Allard, Antoine; Young, Jean-Gabriel; Dubé, Louis J

    2015-12-01

    Real complex systems are not rigidly structured; no clear rules or blueprints exist for their construction. Yet, amidst their apparent randomness, complex structural properties universally emerge. We propose that an important class of complex systems can be modeled as an organization of many embedded levels (potentially infinite in number), all of them following the same universal growth principle known as preferential attachment. We give examples of such hierarchy in real systems, for instance, in the pyramid of production entities of the film industry. More importantly, we show how real complex networks can be interpreted as a projection of our model, from which their scale independence, their clustering, their hierarchy, their fractality, and their navigability naturally emerge. Our results suggest that complex networks, viewed as growing systems, can be quite simple, and that the apparent complexity of their structure is largely a reflection of their unobserved hierarchical nature. PMID:26764746

  16. Diagnostic features of emotional expressions are processed preferentially.

    Directory of Open Access Journals (Sweden)

    Elisa Scheller

    Full Text Available Diagnostic features of emotional expressions are differentially distributed across the face. The current study examined whether these diagnostic features are preferentially attended to even when they are irrelevant for the task at hand or when faces appear at different locations in the visual field. To this aim, fearful, happy and neutral faces were presented to healthy individuals in two experiments while measuring eye movements. In Experiment 1, participants had to accomplish an emotion classification, a gender discrimination or a passive viewing task. To differentiate fast, potentially reflexive, eye movements from a more elaborate scanning of faces, stimuli were either presented for 150 or 2000 ms. In Experiment 2, similar faces were presented at different spatial positions to rule out the possibility that eye movements only reflect a general bias for certain visual field locations. In both experiments, participants fixated the eye region much longer than any other region in the face. Furthermore, the eye region was attended to more pronouncedly when fearful or neutral faces were shown whereas more attention was directed toward the mouth of happy facial expressions. Since these results were similar across the other experimental manipulations, they indicate that diagnostic features of emotional expressions are preferentially processed irrespective of task demands and spatial locations. Saliency analyses revealed that a computational model of bottom-up visual attention could not explain these results. Furthermore, as these gaze preferences were evident very early after stimulus onset and occurred even when saccades did not allow for extracting further information from these stimuli, they may reflect a preattentive mechanism that automatically detects relevant facial features in the visual field and facilitates the orientation of attention towards them. This mechanism might crucially depend on amygdala functioning and it is potentially impaired

  17. Influence of Cononsolvency on the Aggregation of Tertiary Butyl Alcohol in Methanol-Water Mixtures.

    Science.gov (United States)

    Mochizuki, Kenji; Pattenaude, Shannon R; Ben-Amotz, Dor

    2016-07-27

    The term cononsolvency has been used to describe a situation in which a polymer is less soluble (and so is more likely to collapse and aggregate) in a mixture of two cosolvents than it is in either one of the pure solvents. Thus, cononsolvency is closely related to the suppression of protein denaturation by stabilizing osmolytes. Here, we show that cononsolvency behavior can also influence the aggregation of tertiary butyl alcohol in mixtures of water and methanol, as demonstrated using both Raman multivariate curve resolution spectroscopy and molecular dynamics simulations. Our results imply that cononsolvency results from the cosolvent-mediated enhancement of the attractive (solvophobic) mean force between nonpolar groups, driven by preferential solvation of the aggregates, in keeping with Wyman-Tanford theory. PMID:27363494

  18. Fractal Aggregates in Tennis Ball Systems

    Science.gov (United States)

    Sabin, J.; Bandin, M.; Prieto, G.; Sarmiento, F.

    2009-01-01

    We present a new practical exercise to explain the mechanisms of aggregation of some colloids which are otherwise not easy to understand. We have used tennis balls to simulate, in a visual way, the aggregation of colloids under reaction-limited colloid aggregation (RLCA) and diffusion-limited colloid aggregation (DLCA) regimes. We have used the…

  19. Channel Networks

    Science.gov (United States)

    Rinaldo, Andrea; Rodriguez-Iturbe, Ignacio; Rigon, Riccardo

    This review proceeds from Luna Leopold's and Ronald Shreve's lasting accomplishments dealing with the study of random-walk and topologically random channel networks. According to the random perspective, which has had a profound influence on the interpretation of natural landforms, nature's resiliency in producing recurrent networks and landforms was interpreted to be the consequence of chance. In fact, central to models of topologically random networks is the assumption of equal likelihood of any tree-like configuration. However, a general framework of analysis exists that argues that all possible network configurations draining a fixed area are not necessarily equally likely. Rather, a probability P(s) is assigned to a particular spanning tree configuration, say s, which can be generally assumed to obey a Boltzmann distribution: P(s) % e^-H(s)/T, where T is a parameter and H(s) is a global property of the network configuration s related to energetic characters, i.e. its Hamiltonian. One extreme case is the random topology model where all trees are equally likely, i.e. the limit case for T6 4 . The other extreme case is T 6 0, and this corresponds to network configurations that tend to minimize their total energy dissipation to improve their likelihood. Networks obtained in this manner are termed optimal channel networks (OCNs). Observational evidence suggests that the characters of real river networks are reproduced extremely well by OCNs. Scaling properties of energy and entropy of OCNs suggest that large network development is likely to effectively occur at zero temperature (i.e. minimizing its Hamiltonian). We suggest a corollary of dynamic accessibility of a network configuration and speculate towards a thermodynamics of critical self-organization. We thus conclude that both chance and necessity are equally important ingredients for the dynamic origin of channel networks---and perhaps of the geometry of nature.

  20. Crowding alone cannot account for cosolute effect on amyloid aggregation.

    Directory of Open Access Journals (Sweden)

    Shahar Sukenik

    Full Text Available Amyloid fiber formation is a specific form of protein aggregation, often resulting from the misfolding of native proteins. Aimed at modeling the crowded environment of the cell, recent experiments showed a reduction in fibrillation halftimes for amyloid-forming peptides in the presence of cosolutes that are preferentially excluded from proteins and peptides. The effect of excluded cosolutes has previously been attributed to the large volume excluded by such inert cellular solutes, sometimes termed "macromolecular crowding". Here, we studied a model peptide that can fold to a stable monomeric β-hairpin conformation, but under certain solution conditions aggregates in the form of amyloid fibrils. Using Circular Dichroism spectroscopy (CD, we found that, in the presence of polyols and polyethylene glycols acting as excluded cosolutes, the monomeric β-hairpin conformation was stabilized with respect to the unfolded state. Stabilization free energy was linear with cosolute concentration, and grew with molecular volume, as would also be predicted by crowding models. After initiating the aggregation process with a pH jump, fibrillation in the presence and absence of cosolutes was followed by ThT fluorescence, transmission electron microscopy, and CD spectroscopy. Polyols (glycerol and sorbitol increased the lag time for fibril formation and elevated the amount of aggregated peptide at equilibrium, in a cosolute size and concentration dependent manner. However, fibrillation rates remained almost unaffected by a wide range of molecular weights of soluble polyethylene glycols. Our results highlight the importance of other forces beyond the excluded volume interactions responsible for crowding that may contribute to the cosolute effects acting on amyloid formation.

  1. Uplink Inter-Site Carrier Aggregation Between Macro and Small Cells in Heterogeneous Networks

    DEFF Research Database (Denmark)

    Wang, Hua; Rosa, Claudio; Pedersen, Klaus I.

    2014-01-01

    With uplink inter-site carrier aggregation (CA), it is possible to configure a user equipment (UE) to transmit on multiple layers (macro and small cells) simultaneously, each of which may exhibit different radio channel characteristics. This introduces new challenging issues such as how to config......With uplink inter-site carrier aggregation (CA), it is possible to configure a user equipment (UE) to transmit on multiple layers (macro and small cells) simultaneously, each of which may exhibit different radio channel characteristics. This introduces new challenging issues such as how...

  2. Dual-permeability modeling of preferential bromide leaching from a tile-drained glacial till agricultural field

    Science.gov (United States)

    Gerke, Horst H.; Maximilian Köhne, J.

    2004-04-01

    only predicts concentration peaks in initial leaching phases during early time events of the experiment but also the observed reverse reaction of decreased effluent concentrations in initial phases of leaching events during later times of the experiment. The latter occurs when bromide-free infiltrating water is diluting bromide concentrations in the fracture domain such that less concentrated water is preferentially draining from tiles in initial phases of infiltration. Bromide effluent concentrations gradually increase in later phases since vertical flow velocities decrease while 'diffusive' solute transfer from the soil matrix continues. Mass transfer restrictions (e.g. due to soil aggregate coatings) may effectively be controlling preferential leaching at this site.

  3. Quantum Diffusion-Limited Aggregation

    CERN Document Server

    Johnson, David B

    2011-01-01

    Though classical random walks have been studied for many years, research concerning their quantum analogues, quantum random walks, has only come about recently. Numerous simulations of both types of walks have been run and analyzed, and are generally well-understood. Research pertaining to one of the more important properties of classical random walks, namely, their ability to build fractal structures in diffusion-limited aggregation, has been particularly noteworthy. However, only now has research begun in this area in regards to quantum random motion. The study of random walks and the structures they build has various applications in materials science. Since all processes are quantum in nature, it is important to consider the quantum variant of diffusion-limited aggregation. Recognizing that Schr\\"odinger equation and a classical random walk are both diffusion equations, it is possible to connect and compare them. Using similar parameters for both equations, we ran various simulations aggregating particles....

  4. Molecular Aggregation in Disodium Cromoglycate

    Science.gov (United States)

    Singh, Gautam; Agra-Kooijman, D.; Collings, P. J.; Kumar, Satyendra

    2012-02-01

    Details of molecular aggregation in the mesophases of the anti-asthmatic drug disodium cromoglycate (DSCG) have been studied using x-ray synchrotron scattering. The results show two reflections, one at wide angles corresponding to π-π stacking (3.32 å) of molecules, and the other at small angles which is perpendicular to the direction of molecular stacking and corresponds to the distance between the molecular aggregates. The latter varies from 35 - 41 å in the nematic (N) phase and 27 -- 32 å in the columnar (M) phase. The temperature evolution of the stack height, positional order correlations in the lateral direction, and orientation order parameter were determined in the N, M, and biphasic regions. The structure of the N and M phases and the nature of the molecular aggregation, together with their dependence on temperature and concentration, will be presented.

  5. Photostimulated Aggregation of Metal Aerosols

    CERN Document Server

    Karpov, Sergei V

    2010-01-01

    The effect of optical radiation on the rate of aggregation of nanoscopic particles is studied in metal aerosols. It has been shown that under light exposure, polydisperse metal aerosols can aggregate up to two orders faster due to the size dependent photoelectron effect from nanoparticles. Different size nanoparticles undergo mutual heteropolar charging when exchanging photoelectrons through the interparticle medium to result in an increased rate of aggregation. It is shown that long-range electrostatic attractive forces drive the particles into closer distances where the short-range Van-der-Waals forces become dominating. Attention is drawn to the fact that this effect may occur in various types of dispersed systems as well as in natural heteroaerosols.

  6. Balancing energy flexibilities through aggregation

    DEFF Research Database (Denmark)

    Valsomatzis, Emmanouil; Hose, Katja; Pedersen, Torben Bach

    2014-01-01

    in both energy production and consumption, is the key to solving these problems. Flexibilities can be expressed as flex-offers, which due to their high number need to be aggregated to reduce the complexity of energy scheduling. In this paper, we discuss balance aggregation techniques that already......One of the main goals of recent developments in the Smart Grid area is to increase the use of renewable energy sources. These sources are characterized by energy fluctuations that might lead to energy imbalances and congestions in the electricity grid. Exploiting inherent flexibilities, which exist...... during aggregation aim at balancing flexibilities in production and consumption to reduce the probability of congestions and reduce the complexity of scheduling. We present results of our extensive experiments....

  7. Individual income, incomplete information, and aggregate consumption

    OpenAIRE

    Pischke, J.

    1991-01-01

    In this paper I study a model of life-cycle consumption in which individuals react optimally to their own income process but ignore economy wide information. Since individual income is less persistent than aggregate income consumers will react too little to aggregate income variation. Aggregate consumption will be excessively smooth. Since aggregate information is slowly incorporated into consumption, aggregate consumption will be autocorrelated and correlated with lagged income. The second p...

  8. Erythrocyte aggregation: Basic aspects and clinical importance

    OpenAIRE

    Başkurt, Oğuz K.; Meiselman, Herbert J.

    2013-01-01

    Red blood cells (RBC) aggregate to form two- and three-dimensional structures when suspended in aqueous solutions containing large plasma proteins or polymers; this aggregation is reversible and shear dependent (i.e., dispersed at high shear and reformed at low or stasis). The extent of aggregation is the main determinant of low shear blood viscosity, thus predicting an inverse relationship between aggregation and in vivo blood flow. However, the effects of aggregation on hemodynamic mechanis...

  9. SHAPE CHARACTERIZATION OF CONCRETE AGGREGATE

    Directory of Open Access Journals (Sweden)

    Jing Hu

    2011-05-01

    Full Text Available As a composite material, the performance of concrete materials can be expected to depend on the properties of the interfaces between its two major components, aggregate and cement paste. The microstructure at the interfacial transition zone (ITZ is assumed to be different from the bulk material. In general, properties of conventional concrete have been found favoured by optimum packing density of the aggregate. Particle size is a common denominator in such studies. Size segregation in the ITZ among the binder particles in the fresh state, observed in simulation studies by concurrent algorithm-based SPACE system, additionally governs density as well as physical bonding capacity inside these shell-like zones around aggregate particles. These characteristics have been demonstrated qualitatively pertaining also after maturation of the concrete. Such properties of the ITZs have direct impact on composite properties. Despite experimental approaches revealed effects of aggregate grain shape on different features of material structure (among which density, and as a consequence on mechanical properties, it is still an underrated factor in laboratory studies, probably due to the general feeling that a suitable methodology for shape characterization is not available. A scientific argument hindering progress is the interconnected nature of size and shape. Presently, a practical problem preventing shape effects to be emphasized is the limitation of most computer simulation systems in concrete technology to spherical particles. New developments at Delft University of Technology will make it possible in the near future to generate jammed states, or other high-density fresh particle mixtures of non-spherical particles, which thereupon can be subjected to hydration algorithms. This paper will sketch the outlines of a methodological approach for shape assessment of loose (non-embedded aggregate grains, and demonstrate its use for two types of aggregate, allowing

  10. Environmentalism and natural aggregate mining

    Science.gov (United States)

    Drew, L.J.; Langer, W.H.; Sachs, J.S.

    2002-01-01

    Sustaining a developed economy and expanding a developing one require the use of large volumes of natural aggregate. Almost all human activity (commercial, recreational, or leisure) is transacted in or on facilities constructed from natural aggregate. In our urban and suburban worlds, we are almost totally dependent on supplies of water collected behind dams and transported through aqueducts made from concrete. Natural aggregate is essential to the facilities that produce energy-hydroelectric dams and coal-fired powerplants. Ironically, the utility created for mankind by the use of natural aggregate is rarely compared favorably with the environmental impacts of mining it. Instead, the empty quarries and pits are seen as large negative environmental consequences. At the root of this disassociation is the philosophy of environmentalism, which flavors our perceptions of the excavation, processing, and distribution of natural aggregate. The two end-member ideas in this philosophy are ecocentrism and anthropocentrism. Ecocentrism takes the position that the natural world is a organism whose arteries are the rivers-their flow must not be altered. The soil is another vital organ and must not be covered with concrete and asphalt. The motto of the ecocentrist is "man must live more lightly on the land." The anthropocentrist wants clean water and air and an uncluttered landscape for human use. Mining is allowed and even encouraged, but dust and noise from quarry and pit operations must be minimized. The large volume of truck traffic is viewed as a real menace to human life and should be regulated and isolated. The environmental problems that the producers of natural aggregate (crushed stone and sand and gravel) face today are mostly difficult social and political concerns associated with the large holes dug in the ground and the large volume of heavy truck traffic associated with quarry and pit operations. These concerns have increased in recent years as society's demand for

  11. Mechanism of cellular response to nanoscale aggregates of small molecules

    Science.gov (United States)

    Kuang, Yi

    This dissertation research focused on the illustration of the molecular mechanism of cellular response to nanoscale aggregates formed by small molecules. There are five chapters in this dissertation. Chapter 1 summarizes the current research on the evaluation of cell response (i.e., biocompatibility/cytotoxicity) to small molecular hydrogelators. Chapter 2 describes an interesting phenomenon that supramolecular hydrogelators consisting of N-terminated dipeptides, which exhibit selective inhibitory effects against cancer cells. This study calls for the development of a new approach for identification of protein targets of the hydrogelators. Chapter 3 describes the evaluation of interactions between cytosol proteins of a mammalian cell line and morphologically different nanoscale molecular aggregates formed by small peptidic molecules. Chapter 4 describes the research on the mechanism of a type of molecular aggregates, which cluster short microtubules to prevent the growth of microtubule. This unprecedented mechanism of "self-assembly to interfere with self-organization " contributes to inhibiting growth of cancer cells in several mammalian cell based assays and a xenograft tumor mice model. At the end, Chapter 5 reports a novel supramolecular hydrogelator, which consists of fluorene and the pentapeptide epitope (TIGYG) of potassium ion (K+) channels, to self-assemble in water to form the tunable, hierarchical nanostructures dictated by the concentration of K+. In conclusion, this dissertation research demonstrates a new approach for investigating cellular target and molecular mechanism of self-assembled aggregates formed by small peptide derivatives based hydrogelators, which will make contribution to the development of supramolecular hydrogelators as biomaterials. Moreover, the differential cytotoxicity of molecular aggregates illustrated in this research promises a new direction for developing anti-cancer drug based on interactions between molecular aggregates and

  12. How Do the Size, Charge and Shape of Nanoparticles Affect Amyloid β Aggregation on Brain Lipid Bilayer?

    Science.gov (United States)

    Kim, Yuna; Park, Ji-Hyun; Lee, Hyojin; Nam, Jwa-Min

    2016-01-01

    Here, we studied the effect of the size, shape, and surface charge of Au nanoparticles (AuNPs) on amyloid beta (Aβ) aggregation on a total brain lipid-based supported lipid bilayer (brain SLB), a fluid platform that facilitates Aβ-AuNP aggregation process. We found that larger AuNPs induce large and amorphous aggregates on the brain SLB, whereas smaller AuNPs induce protofibrillar Aβ structures. Positively charged AuNPs were more strongly attracted to Aβ than negatively charged AuNPs, and the stronger interactions between AuNPs and Aβ resulted in fewer β-sheets and more random coil structures. We also compared spherical AuNPs, gold nanorods (AuNRs), and gold nanocubes (AuNCs) to study the effect of nanoparticle shape on Aβ aggregation on the brain SLB. Aβ was preferentially bound to the long axis of AuNRs and fewer fibrils were formed whereas all the facets of AuNCs interacted with Aβ to produce the fibril networks. Finally, it was revealed that different nanostructures induce different cytotoxicity on neuroblastoma cells, and, overall, smaller Aβ aggregates induce higher cytotoxicity. The results offer insight into the roles of NPs and brain SLB in Aβ aggregation on the cell membrane and can facilitate the understanding of Aβ-nanostructure co-aggregation mechanism and tuning Aβ aggregate structures.

  13. Susceptibility and predictability of conditions for preferential flow

    Science.gov (United States)

    Wang, Zhi; Feyen, Jan; Ritsema, Coen J.

    1998-09-01

    Preferential flow in the field might be caused by various factors and is difficult to observe in situ. This experimental study was designed to identify the combined effects of air entrapment, surface desaturation (suction head), soil layering, and water repellency (hydrophobicity) of the porous media on unstable preferential flow (or fingering) in the vadose zone. The predictability of unstable flow was studied on the basis of two existing criteria for gravity fingering: (1) a velocity criterion proposed by Hill and Parlange [1972] and (2) a pressure head criterion by Raats [1973] and Philip [1975]. Two-dimensional transparent chambers (60 cm high, 41.5 cm wide, and 2.8 cm thick and 90 cm deep, 74.5 cm wide, and 1.8 cm thick) were used to visualize water infiltration into a water-wettable sand, a water-wettable loam, differently layered sand and loam, and a water-repellent sand. The results suggested that infiltration into the homogeneous sand and a sand-over-loam system, without the effects of air entrapment and surface desaturation, was unconditionally stable. Infiltration into the loam was also stable as observed in the limited chambers. The flow was unconditionally unstable in a fine-over-coarse stratified sublayer and conditionally unstable in the homogeneous sand under the effects of air entrapment and surface desaturation. In multiple-layered systems, infiltration flow was semiunstable; fingers developed in the sand layer and were stabilized in the loam. In the repellent sand the wetting front was unstable under low ponding conditions; however, it was stabilized when the ponding depth exceeded the water-bubbling (entry) value of the hydrophobic medium. Both the velocity and pressure head criteria predicted fingering in the sand (layers) with the effects of gravity. However, the criteria failed to predict stable flow in the loam, indicating that the capillary (stabilizing) effects on the flow need to be included in theoretical developments. Finally, the

  14. Preferential concentration of heavy particles in compressible isotropic turbulence

    Science.gov (United States)

    Zhang, Qingqing; Liu, Han; Ma, Zongqiang; Xiao, Zuoli

    2016-05-01

    Numerical simulations of particle-laden compressible isotropic turbulence with Taylor Reynolds number Reλ ˜ 100 are conducted by using a high-order turbulence solver, which is based on high-order compact finite difference method in the whole flow domain and localized artificial diffusivities for discontinuities. For simplicity, only one-way coupling (i.e., the influence of fluid on particles) between the carrier flow and particles is considered. The focus is on the study of the preferential concentration of heavy particles in dissipative scale of turbulence and the underlying mechanisms. Firstly, the effect of Stokes number (St) on the particle distribution in flow of Mach 1.01 (referred to as high-Mach-number case in this study) is investigated as a necessary supplementation for the previous studies in incompressible and weakly compressible flows. It turns out that heavy particles with Stokes number close to unity exhibit the strongest preferential concentration, which is in agreement with the observation in incompressible flow. All types of heavy particles have a tendency to accumulate in high-density regions of the background flow. While all kinds of particles dominantly collect in low-vorticity regions, intermediate and large particles (St = 1 and St = 5) are also found to collect in high-vorticity regions behind the randomly formed shocklets. Secondly, the impact of turbulent Mach number (Mt) (or the compressibility) of the carrier flow on the spatial distribution of the particles with St = 1 is discussed using the simulated compressible flows with Mt being 0.22, 0.68, and 1.01, respectively. In low-Mach-number flow, particles tend to concentrate in regions of low vorticity due to the centrifuge effect of vortices and particle concentration decreases monotonically with the increasing vorticity magnitude. As Mach number increases, the degree of particle clustering is slightly weakened in low-vorticity regions but is enhanced in high-vorticity regions, which

  15. On conduction in a bacterial sodium channel.

    Directory of Open Access Journals (Sweden)

    Simone Furini

    Full Text Available Voltage-gated Na⁺-channels are transmembrane proteins that are responsible for the fast depolarizing phase of the action potential in nerve and muscular cells. Selective permeability of Na⁺ over Ca²⁺ or K⁺ ions is essential for the biological function of Na⁺-channels. After the emergence of the first high-resolution structure of a Na⁺-channel, an anionic coordination site was proposed to confer Na⁺ selectivity through partial dehydration of Na⁺ via its direct interaction with conserved glutamate side chains. By combining molecular dynamics simulations and free-energy calculations, a low-energy permeation pathway for Na⁺ ion translocation through the selectivity filter of the recently determined crystal structure of a prokaryotic sodium channel from Arcobacter butzleri is characterised. The picture that emerges is that of a pore preferentially occupied by two ions, which can switch between different configurations by crossing low free-energy barriers. In contrast to K⁺-channels, the movements of the ions appear to be weakly coupled in Na⁺-channels. When the free-energy maps for Na⁺ and K⁺ ions are compared, a selective site is characterised in the narrowest region of the filter, where a hydrated Na⁺ ion, and not a hydrated K⁺ ion, is energetically stable.

  16. The Stock Market and the Consumer Confidence Channel in Canada

    OpenAIRE

    Lilia Karnizova; Hashmat Khan

    2010-01-01

    When stock prices rise, so does aggregate consumer spending. A traditional explanation for this phenomenon is based on wealth effects. However, movements of the stock market may affect consumer spending indirectly, by influencing consumer confidence. A bullish stock market may make consumers feel more optimistic about the future of the aggregate economy, and hence increase their spending. This paper investigates the existence of the consumer confidence channel of asset price transmission in C...

  17. Flows of granular material in two-dimensional channels

    OpenAIRE

    Bain, Oliver; Billingham, John; Houston, Paul; Lowndes, Ian

    2015-01-01

    Secondary cone-type crushing machines are an important part of the aggregate production process. These devices process roughly crushed material into aggregate of greater consistency and homogeneity. We apply a continuum model for granular materials (`A Constitutive Law For Dense Granular Flows', Nature 441, p727-730, 2006) to flows of granular material in representative two-dimensional channels, applying a cyclic applied crushing stress in lieu of a moving boundary. Using finite element metho...

  18. Channeling experiment

    International Nuclear Information System (INIS)

    Channeling of water flow and tracer transport in real fractures in a granite body at Stripa have been investigated experimentally. The experimental site was located 360 m below the ground level. Two kinds of experiments were performed. In the single hole experiments, 20 cm diameter holes were drilled about 2.5 m into the rock in the plane of the fracture. Specially designed packers were used to inject water into the fracture in 5 cm intervals all along the fracture trace in the hole. The variation of the injection flowrates along the fracture were used to determine the transmissivity variations in the fracture plane. Detailed photographs were taken from inside the hole and the visual fracture aperture was compared with the injection flowrates in the same locations. Geostatistical methods were used to evaluate the results. Five holes were measured in great detail. In addition 7 holes were drilled and scanned by simpler packer systems. A double hole experiment was performed where two parallel holes were drilled in the same fracture plane at nearly 2 m distance. Pressure pulse tests were made between the holes in both directions. Tracers were injected in 5 locations in one hole and monitored for in many locations in the other hole. The single hole experiment and the double hole experiment show that most of the fracture planes are tight but that there are open sections which form connected channels over distances of at least 2 meters. It was also found in the double hole experiment that the investigated fracture was intersected by at least one fracture between the two holes which diverted a large amount of the injected tracers to several distant locations at the tunnel wall. (authours)

  19. E-book aggregators: new services in electronic publishing

    Directory of Open Access Journals (Sweden)

    Tomislav Jakopec

    2015-07-01

    Full Text Available This paper provides the results of the case study conducted on a sample of 17 websites that identify themselves as e-book aggregators, five platforms for content publishing and 16 websites that present themselves as e-book distributors. While conducting the case study, the answers were sought to the questions about location of website, its owners, activities, distribution channels, services, partners, languages, content protection, scope of activities, number of authors and books, publishing areas, formats, etc. Based on the case studies, the results presented focus on the geographical distribution of the analyzed companies, distribution of companies according to the year in which they were established, distribution of companies by activity, the number of different input formats supported by aggregation companies, a separate service of conversion, output formats supported by aggregation companies, distribution on platforms and in bookstores, content protection options, possibilities of editing content in the cloud, models of payment for services, and other identified services. Based on the results of the study, a conclusion is made that e-book aggregation as a business model exists and that its further development will show the extent to which it is sustainable.

  20. Preferential flow, connectivity and the principle of "minimum time to equilibrium": a new perspective on environmental water flow

    Science.gov (United States)

    Zehe, E.; Blume, T.; Bloeschl, G.

    2008-12-01

    Preferential/rapid flow and transport is known as one key process in soil hydrology for more than 20 years. It seems to be rather the rule, than the exception. It occurs in soils, in surface rills and river networks. If connective preferential are present at any scale, they crucially control water flow and solute transport. Why? Is there an underlying principle? If energy is conserved a system follows Fermat's principle of minimum action i.e. it follows the trajectory that minimise the integral of the total energy/ La Grangian over time. Hydrological systems are, however, non-conservative as surface and subsurface water flows dissipate energy. From thermodynamics it is well known that natural processes minimize the free energy of the system. For hydrological systems we suggest, therefore, that flow in a catchment arranges in such a way that time to a minimum of free energy becomes minimal for a given rainfall input (disturbance) and under given constraints. Free energy in a soil is determined by potential energy and capillary energy. The pore size distribution of the soil, soil structures, depth to groundwater and most important vegetation make up the constraints. The pore size distribution determines whether potential energy or capillarity dominates the free energy of the soil system. The first term is minimal when the pore space is completely de-saturated the latter becomes minimal at soil saturation. Hence, the soil determines a) the amount of excess (gravity) water that has to be exported from the soil to reach a minimum state of free energy and b) whether redistribution or groundwater recharge is more efficient to reach that equilibrium. On the other hand, the pore size distribution of the soil and the connectivity of preferential pathways (root channels, worm holes and cracks) determine flow velocities and the redistribution of water within the pore space. As water flow and ground water recharge are fast in sandy soils and capillary energy is of minor

  1. The evolution of phenotypes and genetic parameters under preferential mating

    Science.gov (United States)

    Roff, Derek A; Fairbairn, Daphne J

    2014-01-01

    This article extends and adds more realism to Lande's analytical model for evolution under mate choice by using individual-based simulations in which females sample a finite number of males and the genetic architecture of the preference and preferred trait evolves. The simulations show that the equilibrium heritabilities of the preference and preferred trait and the genetic correlation between them (rG), depend critically on aspects of the mating system (the preference function, mode of mate choice, choosiness, and number of potential mates sampled), the presence or absence of natural selection on the preferred trait, and the initial genetic parameters. Under some parameter combinations, preferential mating increased the heritability of the preferred trait, providing a possible resolution for the lek paradox. The Kirkpatrick–Barton approximation for rG proved to be biased downward, but the realized genetic correlations were also low, generally <0.2. Such low values of rG indicate that coevolution of the preference and preferred trait is likely to be very slow and subject to significant stochastic variation. Lande's model accurately predicted the incidence of runaway selection in the simulations, except where preferences were relative and the preferred trait was subject to natural selection. In these cases, runaways were over- or underestimated, depending on the number of males sampled. We conclude that rapid coevolution of preferences and preferred traits is unlikely in natural populations, but that the parameter combinations most conducive to it are most likely to occur in lekking species. PMID:25077025

  2. Functional hierarchy underlies preferential connectivity disturbances in schizophrenia.

    Science.gov (United States)

    Yang, Genevieve J; Murray, John D; Wang, Xiao-Jing; Glahn, David C; Pearlson, Godfrey D; Repovs, Grega; Krystal, John H; Anticevic, Alan

    2016-01-12

    Schizophrenia may involve an elevated excitation/inhibition (E/I) ratio in cortical microcircuits. It remains unknown how this regulatory disturbance maps onto neuroimaging findings. To address this issue, we implemented E/I perturbations within a neural model of large-scale functional connectivity, which predicted hyperconnectivity following E/I elevation. To test predictions, we examined resting-state functional MRI in 161 schizophrenia patients and 164 healthy subjects. As predicted, patients exhibited elevated functional connectivity that correlated with symptom levels, and was most prominent in association cortices, such as the fronto-parietal control network. This pattern was absent in patients with bipolar disorder (n = 73). To account for the pattern observed in schizophrenia, we integrated neurobiologically plausible, hierarchical differences in association vs. sensory recurrent neuronal dynamics into our model. This in silico architecture revealed preferential vulnerability of association networks to E/I imbalance, which we verified empirically. Reported effects implicate widespread microcircuit E/I imbalance as a parsimonious mechanism for emergent inhomogeneous dysconnectivity in schizophrenia. PMID:26699491

  3. Preferential rotation of chiral dipoles in isotropic turbulence

    CERN Document Server

    Kramel, Stefan; Toschi, Federico; Voth, Greg A

    2016-01-01

    Particles in the shape of chiral dipoles show a preferential rotation in three dimensional homogeneous isotropic turbulence. A chiral dipole consists of a rod with two helices of opposite handedness, one at each end. We can use 3d printing to fabricate these particles with length in the inertial range and track their rotations in a turbulent flow between oscillating grids. High aspect ratio chiral dipoles will align with the extensional eigenvectors of the strain rate tensor and the helical ends will respond to the strain field by spinning around its long axis. The mean of the measured spinning rate is non-zero and reflects the average stretching the particles experience. We use Stokesian dynamics simulations of chiral dipoles in pure strain flow to quantify the dependence of spinning on particle shape. Based on the known response to pure strain, we build a model that gives the spinning rate of small chiral dipoles using Lagrangian velocity gradients from high resolution direct numerical simulations. The stat...

  4. Upper visual field distractors preferentially bias attention to the left.

    Science.gov (United States)

    Thomas, Nicole A; Castine, Benjamin R; Loetscher, Tobias; Nicholls, Michael E R

    2015-03-01

    Pseudoneglect is influenced by vertical visual field stimulation, such that attentional biases are stronger for upper space distractors. Leftward biases result from right hemisphere visuospatial processing, and may be accentuated by additional right hemisphere activation during upper space distraction. Three experiments examined potential explanations for this finding. Experiment 1 controlled for perceptual grouping and leftward biases remained stronger in upper space. Experiment 2 used peripheral distractors to eliminate two further potential explanations: centre-of-mass and framing effects. Eye tracking was included to compare overt and covert attention. Findings supported the occurrence of a stronger leftward attentional bias during upper space distraction. Distractors were rarely fixated, suggesting covert attentional mechanisms are preferentially drawn toward upper space distractors. Experiment 3 employed a cueing paradigm that purposefully directed attention away from centre to determine whether pseudoneglect was influenced by overt attentional orienting. Results indicated that when attention was overtly directed away from centre, the strength of pseudoneglect did not differ based on visual field. It is concluded that covert attention toward upper space distractors recruits additional right hemisphere activation, leading existing leftward biases to be accentuated. PMID:25437374

  5. Preferential translation of chloroplast ribosomal proteins in Chlamydomonas reinhardtti

    International Nuclear Information System (INIS)

    The nuclear cr-1 mutant of C. reinhardtii is deficient in the 30S subunit of the chloroplast (cp) ribosome and in cp protein synthesis. The cp spectinomycin resistant mutant, spr-u-1-27-3, has a normal level of 70S ribosomes but only a low rate of cp protein synthesis with spectinomycin present. In both mutants there is little accumulation of the large subunit of ribulose 1,5-bisphosphate carboxylase (Rubisco LSU), but near wild-type levels of cp synthesized r-proteins. In cells pulse-labelled with 35SO4 and immunoprecipitated with specific antisera, the ratio of the rate of synthesis of cp r-proteins to that of Rubisco LSU is 7 times greater in both mutants than in wild-type. No difference in the rate of turnover between r-proteins and Rubisco LSU in mutant and wild-type cells was observed during a one hour chase. The mRNA levels for r-protein L1 and Rubisco LSU actually increase slightly in the mutants. These data suggest that C. reinhardtii has a translation mechanism for preferential synthesis of cp r-proteins that operates under conditions of reduced total cp protein synthesis

  6. Preferential Iron Trafficking Characterizes Glioblastoma Stem-like Cells

    DEFF Research Database (Denmark)

    Schonberg, David L; Miller, Tyler E; Wu, Qiulian;

    2015-01-01

    Glioblastomas display hierarchies with self-renewing cancer stem-like cells (CSCs). RNA sequencing and enhancer mapping revealed regulatory programs unique to CSCs causing upregulation of the iron transporter transferrin, the top differentially expressed gene compared with tissue-specific progeni......Glioblastomas display hierarchies with self-renewing cancer stem-like cells (CSCs). RNA sequencing and enhancer mapping revealed regulatory programs unique to CSCs causing upregulation of the iron transporter transferrin, the top differentially expressed gene compared with tissue......-specific progenitors. Direct interrogation of iron uptake demonstrated that CSCs potently extract iron from the microenvironment more effectively than other tumor cells. Systematic interrogation of iron flux determined that CSCs preferentially require transferrin receptor and ferritin, two core iron regulators......, to propagate and form tumors in vivo. Depleting ferritin disrupted CSC mitotic progression, through the STAT3-FoxM1 regulatory axis, revealing an iron-regulated CSC pathway. Iron is a unique, primordial metal fundamental for earliest life forms, on which CSCs have an epigenetically programmed, targetable...

  7. Renewables, Preferential Trade Agreements and EU Energy Security

    Directory of Open Access Journals (Sweden)

    Rafael Leal-Arcas

    2015-08-01

    Full Text Available A major aim of the international community is to decarbonize the economy. With renewables, international trade in energy is likely to increase. In turn, the international trading system can be a major vehicle towards moving away from fossil fuels to renewable energy. To this end, it can provide fair competition, economies of scale and knowledge transfer. This article analyzes the impact of European Union (EU preferential trade agreements (PTAs in addressing climate change mitigation and energy security by promoting renewables. Currently, there is a proliferation of PTAs; this trend seems irreversible and is likely to persist, given the current crisis in the multilateral trading system. We argue that the EU can, through its network of PTAs, move towards greater energy independence as renewable energy becomes increasingly economically viable. This article provides a thorough review of the renewable energy-related provisions in the EU’s current PTAs and recommends three tangible ways through which the EU could capitalize its vast network of PTAs to boost the renewable energy market.

  8. Effect of reactor heat transfer limitations on CO preferential oxidation

    Science.gov (United States)

    Ouyang, X.; Besser, R. S.

    Our recent studies of CO preferential oxidation (PrOx) identified systematic differences between the characteristic curves of CO conversion for a microchannel reactor with thin-film wall catalyst and conventional mini packed-bed lab reactors (m-PBR's). Strong evidence has suggested that the reverse water-gas-shift (r-WGS) side reaction activated by temperature gradients in m-PBR's is the source of these differences. In the present work, a quasi-3D tubular non-isothermal reactor model based on the finite difference method was constructed to quantitatively study the effect of heat transport resistance on PrOx reaction behavior. First, the kinetic expressions for the three principal reactions involved were formed based on the combination of experimental data and literature reports and their parameters were evaluated with a non-linear regression method. Based on the resulting kinetic model and an energy balance derived for PrOx, the finite difference method was then adopted for the quasi-3D model. This model was then used to simulate both the microreactor and m-PBR's and to gain insights into their different conversion behavior. Simulation showed that the temperature gradients in m-PBR's favor the reverse water-gas-shift (r-WGS) reaction, thus causing a much narrower range of permissible operating temperature compared to the microreactor. Accordingly, the extremely efficient heat removal of the microchannel/thin-film catalyst system eliminates temperature gradients and efficiently prevents the onset of the r-WGS reaction.

  9. Lysosomal disruption preferentially targets acute myeloid leukemia cells and progenitors

    Science.gov (United States)

    Sukhai, Mahadeo A.; Prabha, Swayam; Hurren, Rose; Rutledge, Angela C.; Lee, Anna Y.; Sriskanthadevan, Shrivani; Sun, Hong; Wang, Xiaoming; Skrtic, Marko; Seneviratne, Ayesh; Cusimano, Maria; Jhas, Bozhena; Gronda, Marcela; MacLean, Neil; Cho, Eunice E.; Spagnuolo, Paul A.; Sharmeen, Sumaiya; Gebbia, Marinella; Urbanus, Malene; Eppert, Kolja; Dissanayake, Dilan; Jonet, Alexia; Dassonville-Klimpt, Alexandra; Li, Xiaoming; Datti, Alessandro; Ohashi, Pamela S.; Wrana, Jeff; Rogers, Ian; Sonnet, Pascal; Ellis, William Y.; Corey, Seth J.; Eaves, Connie; Minden, Mark D.; Wang, Jean C.Y.; Dick, John E.; Nislow, Corey; Giaever, Guri; Schimmer, Aaron D.

    2012-01-01

    Despite efforts to understand and treat acute myeloid leukemia (AML), there remains a need for more comprehensive therapies to prevent AML-associated relapses. To identify new therapeutic strategies for AML, we screened a library of on- and off-patent drugs and identified the antimalarial agent mefloquine as a compound that selectively kills AML cells and AML stem cells in a panel of leukemia cell lines and in mice. Using a yeast genome-wide functional screen for mefloquine sensitizers, we identified genes associated with the yeast vacuole, the homolog of the mammalian lysosome. Consistent with this, we determined that mefloquine disrupts lysosomes, directly permeabilizes the lysosome membrane, and releases cathepsins into the cytosol. Knockdown of the lysosomal membrane proteins LAMP1 and LAMP2 resulted in decreased cell viability, as did treatment of AML cells with known lysosome disrupters. Highlighting a potential therapeutic rationale for this strategy, leukemic cells had significantly larger lysosomes compared with normal cells, and leukemia-initiating cells overexpressed lysosomal biogenesis genes. These results demonstrate that lysosomal disruption preferentially targets AML cells and AML progenitor cells, providing a rationale for testing lysosomal disruption as a novel therapeutic strategy for AML. PMID:23202731

  10. An algorithm for preferential selection of spectroscopic targets in LEGUE

    Institute of Scientific and Technical Information of China (English)

    Jeffrey L.Carlin; Carl J.Grillmair; Puragra Guhathakurta; Zhan-Wen Han; Jin-Liang Hou; Hsu-Tai Lee; Jing Li; Chao Liu; Xiao-Wei Liu; Kai-Ke Pan; J.A.Sellwood; Sébastien Lépine; Hong-Chi Wang; Fan Yang; Brian Yanny; Yue-Yang Zhang; Zheng Zheng; Zi Zhu; Heidi Jo Newberg; Li-Cai Deng; Timothy C.Beers; Yu-Qin Chen; Norbert Christlieb; Xiao-Ting Fu; Shuang Gao

    2012-01-01

    We describe a general target selection algorithm that is applicable to any survey in which the number of available candidates is much larger than the number of objects to be observed.This routine aims to achieve a balance between a smoothlyvarying,well-understood selection function and the desire to preferentially select certain types of targets.Some target-selection examples are shown that illustrate different possibilities of emphasis functions.Although it is generally applicable,the algorithm was developed specifically for the LAMOST Experiment for Galactic Understanding and Exploration(LEGUE)survey that will be carried out using the Chinese Guo Shou Jing Telescope.In particular,this algorithm was designed for the portion of LEGUE targeting the Galactic halo,in which we attempt to balance a variety of science goals that require stars at fainter magnitudes than can be completely sampled by LAMOST.This algorithm has been implemented for the halo portion of the LAMOST pilot survey,which began in October 2011.

  11. Studies on recycled aggregates-based concrete.

    Science.gov (United States)

    Rakshvir, Major; Barai, Sudhirkumar V

    2006-06-01

    Reduced extraction of raw materials, reduced transportation cost, improved profits, reduced environmental impact and fast-depleting reserves of conventional natural aggregates has necessitated the use of recycling, in order to be able to conserve conventional natural aggregate. In this study various physical and mechanical properties of recycled concrete aggregates were examined. Recycled concrete aggregates are different from natural aggregates and concrete made from them has specific properties. The percentages of recycled concrete aggregates were varied and it was observed that properties such as compressive strength showed a decrease of up to 10% as the percentage of recycled concrete aggregates increased. Water absorption of recycled aggregates was found to be greater than natural aggregates, and this needs to be compensated during mix design. PMID:16784165

  12. Diversity, intent, and aggregated search

    NARCIS (Netherlands)

    M. de Rijke

    2014-01-01

    Diversity, intent and aggregated search are three core retrieval concepts that receive significant attention. In search result diversification one typically considers the relevance of a document in light of other retrieved documents. The goal is to identify the probable "aspects" of an ambiguous que

  13. Excitons in tubular molecular aggregates

    NARCIS (Netherlands)

    Didraga, C; Knoester, J

    2004-01-01

    We present a brief overview of recent work on the optical properties of molecular aggregates with a tubular (cylindrical) shape. The exciton states responsible for these properties can be distinguished with regard to a transverse wave number, which directly relates to optical selection rules and pol

  14. Cyclosporine A enhances platelet aggregation.

    Science.gov (United States)

    Grace, A A; Barradas, M A; Mikhailidis, D P; Jeremy, J Y; Moorhead, J F; Sweny, P; Dandona, P

    1987-12-01

    In view of the reported increase in thromboembolic episodes following cyclosporine A (CyA) therapy, the effect of this drug on platelet aggregation and thromboxane A2 release was investigated. The addition of CyA, at therapeutic concentrations to platelet rich plasma from normal subjects in vitro was found to increase aggregation in response to adrenaline, collagen and ADP. Ingestion of CyA by healthy volunteers was also associated with enhanced platelet aggregation. The CyA-mediated enhancement of aggregation was further enhanced by the addition in vitro of therapeutic concentrations of heparin. Platelets from renal allograft recipients treated with CyA also showed hyperaggregability and increased thromboxane A2 release, which were most marked at "peak" plasma CyA concentration and less so at "trough" concentrations. Platelet hyperaggregability in renal allograft patients on long-term CyA therapy tended to revert towards normal following the replacement of CyA with azathioprine. Hypertensive patients with renal allografts on nifedipine therapy had normal platelet function and thromboxane release in spite of CyA therapy. These observations suggest that CyA-mediated platelet activation may contribute to the pathogenesis of the thromboembolic phenomena associated with the use of this drug. The increased release of thromboxane A2 (a vasoconstrictor) may also play a role in mediating CyA-related nephrotoxicity.

  15. Using Information Aggregation Markets for Decision Support

    Directory of Open Access Journals (Sweden)

    Patrick Buckley

    2012-06-01

    Full Text Available Information Aggregation Markets, often referred to as prediction markets, are markets that are designed to aggregate information from a disparate pool of human individuals to make predictions about the likely outcome of future uncertain events. This paper looks at how Information Aggregation Markets can be incorporated into the standard body of decision making theory. It examines how Information Aggregation Markets can be used as decision support systems, and provides empirical evidence from a wide variety of sources as to the effectiveness and practicality of Information Aggregation Markets. Finally, this paper details some future research questions to be addressed in the area of Information Aggregation Markets.

  16. Preferential Intercalation of Pyridinedicarboxylates into Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    李蕾; 莫丹; 陈大舟

    2005-01-01

    Intercalation of 2,3-,2,4-,2,5-,2,6-,3,4-,or3,5-pyridincdicarboxylate into the layered double hydroxide (LDH),[Mg0.73AIo.27(OH)2](CO3)0.14*1.34H2O was carried out by the reconstruction method in the molar ratio of organic acid: calcined LDH=3:8, in 80% alcoholic aqueous solution at 70℃. Selective reaction was observed in com-petitive experiments involving an equal concentration pairs of acids. The preference order of the organic acids intercalated into the Mg-Al-LDH was found to be in the order of 2,3-pyridinedicarboxylate>2,5-pyridinedicarboxylate>2,4-pyridinedicarboxylate>3,5-pyridinedicarboxylate>3,4-pyridinedicarboxylate>2,6-pyridinedic arboxylate. The structures of the intercalates formed by the reaction of six guests with Mg-Al-LDH were characterized by X-ray diffraction, infrared and thermogravimetry techniques. And the charge density on the oxygens of each of the carboxylate groups for the six anions was investigated utilizing ab initio (HF/6-31G) method by G98w. From the X-ray diffraction data, the guest size and the charge density of the oxygens of the guest, the orientation of 2,3-,2,4-,2,5-,2,6-,3,4-, or 3,5-pyridinedicarboxylate anions between the layers was determined and the preferential intercalation mechanism was discussed. These results indicate the possibility of a molecular recognition ability of LDH and it would be exploited for the chemical separation of some anions from solution.

  17. Frac Sand Mines Are Preferentially Sited in Unzoned Rural Areas

    Science.gov (United States)

    Locke, Christina

    2015-01-01

    Shifting markets can cause unexpected, stochastic changes in rural landscapes that may take local communities by surprise. Preferential siting of new industrial facilities in poor areas or in areas with few regulatory restrictions can have implications for environmental sustainability, human health, and social justice. This study focuses on frac sand mining—the mining of high-quality silica sand used in hydraulic fracturing processes for gas and oil extraction. Frac sand mining gained prominence in the 2000s in the upper midwestern United States where nonmetallic mining is regulated primarily by local zoning. I asked whether frac sand mines were more commonly sited in rural townships without formal zoning regulations or planning processes than in those that undertook zoning and planning before the frac sand boom. I also asked if mine prevalence was correlated with socioeconomic differences across townships. After creating a probability surface to map areas most suitable for frac sand mine occurrence, I developed neutral landscape models from which to compare actual mine distributions in zoned and unzoned areas at three different spatial extents. Mines were significantly clustered in unzoned jurisdictions at the statewide level and in 7 of the 8 counties with at least three frac sand mines and some unzoned land. Subsequent regression analyses showed mine prevalence to be uncorrelated with land value, tax rate, or per capita income, but correlated with remoteness and zoning. The predicted mine count in unzoned townships was over two times higher than that in zoned townships. However, the county with the most mines by far was under a county zoning ordinance, perhaps indicating industry preferences for locations with clear, homogenous rules over patchwork regulation. Rural communities can use the case of frac sand mining as motivation to discuss and plan for sudden land-use predicaments, rather than wait to grapple with unfamiliar legal processes during a period of

  18. Frac Sand Mines Are Preferentially Sited in Unzoned Rural Areas.

    Science.gov (United States)

    Locke, Christina

    2015-01-01

    Shifting markets can cause unexpected, stochastic changes in rural landscapes that may take local communities by surprise. Preferential siting of new industrial facilities in poor areas or in areas with few regulatory restrictions can have implications for environmental sustainability, human health, and social justice. This study focuses on frac sand mining-the mining of high-quality silica sand used in hydraulic fracturing processes for gas and oil extraction. Frac sand mining gained prominence in the 2000s in the upper midwestern United States where nonmetallic mining is regulated primarily by local zoning. I asked whether frac sand mines were more commonly sited in rural townships without formal zoning regulations or planning processes than in those that undertook zoning and planning before the frac sand boom. I also asked if mine prevalence was correlated with socioeconomic differences across townships. After creating a probability surface to map areas most suitable for frac sand mine occurrence, I developed neutral landscape models from which to compare actual mine distributions in zoned and unzoned areas at three different spatial extents. Mines were significantly clustered in unzoned jurisdictions at the statewide level and in 7 of the 8 counties with at least three frac sand mines and some unzoned land. Subsequent regression analyses showed mine prevalence to be uncorrelated with land value, tax rate, or per capita income, but correlated with remoteness and zoning. The predicted mine count in unzoned townships was over two times higher than that in zoned townships. However, the county with the most mines by far was under a county zoning ordinance, perhaps indicating industry preferences for locations with clear, homogenous rules over patchwork regulation. Rural communities can use the case of frac sand mining as motivation to discuss and plan for sudden land-use predicaments, rather than wait to grapple with unfamiliar legal processes during a period of

  19. Frac Sand Mines Are Preferentially Sited in Unzoned Rural Areas.

    Directory of Open Access Journals (Sweden)

    Christina Locke

    Full Text Available Shifting markets can cause unexpected, stochastic changes in rural landscapes that may take local communities by surprise. Preferential siting of new industrial facilities in poor areas or in areas with few regulatory restrictions can have implications for environmental sustainability, human health, and social justice. This study focuses on frac sand mining-the mining of high-quality silica sand used in hydraulic fracturing processes for gas and oil extraction. Frac sand mining gained prominence in the 2000s in the upper midwestern United States where nonmetallic mining is regulated primarily by local zoning. I asked whether frac sand mines were more commonly sited in rural townships without formal zoning regulations or planning processes than in those that undertook zoning and planning before the frac sand boom. I also asked if mine prevalence was correlated with socioeconomic differences across townships. After creating a probability surface to map areas most suitable for frac sand mine occurrence, I developed neutral landscape models from which to compare actual mine distributions in zoned and unzoned areas at three different spatial extents. Mines were significantly clustered in unzoned jurisdictions at the statewide level and in 7 of the 8 counties with at least three frac sand mines and some unzoned land. Subsequent regression analyses showed mine prevalence to be uncorrelated with land value, tax rate, or per capita income, but correlated with remoteness and zoning. The predicted mine count in unzoned townships was over two times higher than that in zoned townships. However, the county with the most mines by far was under a county zoning ordinance, perhaps indicating industry preferences for locations with clear, homogenous rules over patchwork regulation. Rural communities can use the case of frac sand mining as motivation to discuss and plan for sudden land-use predicaments, rather than wait to grapple with unfamiliar legal processes

  20. Schema-conformant memories are preferentially consolidated during REM sleep.

    Science.gov (United States)

    Durrant, Simon J; Cairney, Scott A; McDermott, Cathal; Lewis, Penelope A

    2015-07-01

    Memory consolidation is most commonly described by the standard model, which proposes an initial binding role for the hippocampus which diminishes over time as intracortical connections are strengthened. Recent evidence suggests that slow wave sleep (SWS) plays an essential role in this process. Existing animal and human studies have suggested that memories which fit tightly into an existing knowledge framework or schema might use an alternative consolidation route in which the medial prefrontal cortex takes on the binding role. In this study we sought to investigate the role of sleep in this process using a novel melodic memory task. Participants were asked to remember 32 melodies, half of which conformed to a tonal schema present in all enculturated listeners, and half of which did not fit with this schema. After a 24-h consolidation interval, participants were asked to remember a further 32 melodies, before being given a recognition test in which melodies from both sessions were presented alongside some previously unheard foils. Participants remembered schema-conformant melodies better than non-conformant ones. This was much more strongly the case for consolidated melodies, suggesting that consolidation over a 24-h period preferentially consolidated schema-conformant items. Overnight sleep was monitored between the sessions, and the extent of the consolidation benefit for schema-conformant items was associated with both the amount of REM sleep obtained and EEG theta power in frontal and central regions during REM sleep. Overall our data suggest that REM sleep plays a crucial role in the rapid consolidation of schema-conformant items. This finding is consistent with previous results from animal studies and the SLIMM model of Van Kesteren, Ruiter, Fernández, and Henson (2012), and suggest that REM sleep, rather than SWS, may be involved in an alternative pathway of consolidation for schema-conformant memories.

  1. Enhancing the Data Collection Rate of Tree-Based Aggregation in Wireless Sensor Networks

    NARCIS (Netherlands)

    Durmaz Incel, O.; Krishnamachari, B.

    2008-01-01

    What is the fastest rate at which we can collect a stream of aggregated data from a set of wireless sensors organized as a tree? We explore a hierarchy of techniques using realistic simulation models to address this question. We begin by considering TDMA scheduling on a single channel, reducing the

  2. Elections, information aggregation, and strategic voting

    OpenAIRE

    Feddersen, Timothy; Pesendorfer, Wolfgang

    1999-01-01

    A central role of elections is the aggregation of information dispersed within a population. This article surveys recent work on elections as mechanisms for aggregating information and on the incentives for voters to vote strategically in such elections.

  3. Yeast prions: protein aggregation is not enough.

    OpenAIRE

    Sherman, Michael Y

    2004-01-01

    Although many proteins -- both damaged and normal -- have a tendency to aggregate, only some are capable of dividing and propagating. What does it take to turn a protein aggregate into an infectious prion?

  4. Estimation of Line Efficiency by Aggregation

    NARCIS (Netherlands)

    M.B.M. de Koster (René)

    1987-01-01

    textabstractPresents a multi-stage flow lines with intermediate buffers approximated by two-stage lines using repeated aggregation. Characteristics of the aggregation method; Problems associated with the analysis and design of production lines.

  5. Channel blocking of MspA revisited.

    Science.gov (United States)

    Perera, Ayomi S; Wang, Hongwang; Basel, Matthew T; Pokhrel, Megh Raj; Gamage, Pubudu Siyambalagoda; Kalita, Mausam; Wendel, Sebastian; Sears, Bryan; Welideniya, Dhanushi; Liu, Yao; Turro, Claudia; Troyer, Deryl L; Bossmann, Stefan H

    2013-01-01

    Porin A from Mycobacterium smegmatis (MspA) is a highly stable, octameric channel protein, which acts as the main transporter of electrolytes across the cell membrane. MspA features a narrow, negatively charged constriction zone, allowing stable binding of various analytes thereby blocking the channel. Investigation of channel blocking of mycobacterial porins is of significance in developing alternate treatment methods for tuberculosis. The concept that ruthenium(II)quaterpyridinium complexes have the capability to act as efficient channel blockers for MspA and related porins, emerged after very high binding constants were measured by high-performance liquid chromatography and steady-state luminescence studies. Consequently, the interactions between the ruthenium(II) complex RuC2 molecules and MspA, leading to RuC2@MspA assemblies, have been studied utilizing time-resolved absorption/emission, atomic force microscopy, dynamic light scattering, ζ potential measurements, and isothermal titration calorimetry. The results obtained provide evidence for the formation of clusters/large aggregates of RuC2 and MspA. The results are of interest with respect to utilizing prospective channel blockers in porins. The combination of results from conceptually different techniques shed some light onto the chemical nature of MspA-channel blocker interactions thus contributing to the development of a paradigm for channel blocking. PMID:23214433

  6. Aggregating and Disaggregating Flexibility Objects

    DEFF Research Database (Denmark)

    Siksnys, Laurynas; Valsomatzis, Emmanouil; Hose, Katja;

    2015-01-01

    In many scientific and commercial domains we encounter flexibility objects, i.e., objects with explicit flexibilities in a time and an amount dimension (e.g., energy or product amount). Applications of flexibility objects require novel and efficient techniques capable of handling large amounts...... of such objects while preserving flexibility. Hence, this paper formally defines the concept of flexibility objects (flex-objects) and provides a novel and efficient solution for aggregating and disaggregating flex-objects. Out of the broad range of possible applications, this paper will focus on smart grid...... energy data management and discuss strategies for aggregation and disaggregation of flex-objects while retaining flexibility. This paper further extends these approaches beyond flex-objects originating from energy consumption by additionally considering flex-objects originating from energy production...

  7. Containing Internal Diffusion Limited Aggregation

    CERN Document Server

    Duminil-Copin, Hugo; Yadin, Ariel; Yehudayoff, Amir

    2011-01-01

    Internal Diffusion Limited Aggregation (IDLA) is a model that describes the growth of a random aggregate of particles from the inside out. Shellef proved that IDLA processes on supercritical percolation clusters of integer-lattices fill Euclidean balls, with high probability. In this article, we complete the picture and prove a limit-shape theorem for IDLA on such percolation clusters, by providing the corresponding upper bound. The technique to prove upper bounds is new and robust: it only requires the existence of a "good" lower bound. Specifically, this way of proving upper bounds on IDLA clusters is more suitable for random environments than previous ways, since it does not harness harmonic measure estimates.

  8. Young Children with Autism Spectrum Disorder Do Not Preferentially Attend to Biological Motion

    Science.gov (United States)

    Annaz, Dagmara; Campbell, Ruth; Coleman, Mike; Milne, Elizabeth; Swettenham, John

    2012-01-01

    Preferential attention to biological motion can be seen in typically developing infants in the first few days of life and is thought to be an important precursor in the development of social communication. We examined whether children with autism spectrum disorder (ASD) aged 3-7 years preferentially attend to point-light displays depicting…

  9. Determining the frequency, depth and velocity of preferential flow by high frequency soil moisture monitoring.

    Science.gov (United States)

    Hardie, Marcus; Lisson, Shaun; Doyle, Richard; Cotching, William

    2013-01-01

    Preferential flow in agricultural soils has been demonstrated to result in agrochemical mobilisation to shallow ground water. Land managers and environmental regulators need simple cost effective techniques for identifying soil - land use combinations in which preferential flow occurs. Existing techniques for identifying preferential flow have a range of limitations including; often being destructive, non in situ, small sampling volumes, or are subject to artificial boundary conditions. This study demonstrated that high frequency soil moisture monitoring using a multi-sensory capacitance probe mounted within a vertically rammed access tube, was able to determine the occurrence, depth, and wetting front velocity of preferential flow events following rainfall. Occurrence of preferential flow was not related to either rainfall intensity or rainfall amount, rather preferential flow occurred when antecedent soil moisture content was below 226 mm soil moisture storage (0-70 cm). Results indicate that high temporal frequency soil moisture monitoring may be used to identify soil type - land use combinations in which the presence of preferential flow increases the risk of shallow groundwater contamination by rapid transport of agrochemicals through the soil profile. However use of high frequency based soil moisture monitoring to determine agrochemical mobilisation risk may be limited by, inability to determine the volume of preferential flow, difficulty observing macropore flow at high antecedent soil moisture content, and creation of artificial voids during installation of access tubes in stony soils. PMID:23159761

  10. Preferential flow in water repellent sandy soils; model development and lysimeter experiments.

    NARCIS (Netherlands)

    Rooij, de G.H.

    1996-01-01

    When water enters a water-repellent topsoil, preferential flow paths develop and the flow bypasses a large part of the unsaturated zone. Therefore, preferential flow caused by water- repellency is expected to accelerate solute leaching to the groundwater. In soils with water-repellent toplayers and

  11. ASSESSMENT OF FINE RECYCLED AGGREGATES IN MORTAR

    OpenAIRE

    Feys, Charles; Joseph, Miquel; Boehme, Luc; Zhang, Yunlian

    2016-01-01

    In this study, the influence of fine recycled concrete aggregates as replacement for sand in mortar and the use as cement replacement and filler is investigated. Mortar with fine recycled aggregates is examined on its mechanical and physical properties. The samples are also examined on a microscopic scale. The fine recycled concrete aggregates are made with one-year old concrete made in the laboratory. Fine recycled aggregates (FRCA) are added as a cement replacement (0 %, 10 %...

  12. Computers and Productivity: Are Aggregation Effects Important?

    OpenAIRE

    Robert H. McGuckin; Kevin Stiroh

    2000-01-01

    This paper examines the empirical implications of aggregation bias when measuring the productive impact of computers. To isolate two specific aggregation problems relating to "aggregation in variables" and "aggregation in relations," we compare various production function estimates across a range of specifications, econometric estimators, and data levels. The results show that both sources of bias are important, especially as one moves from the sector to the economy level, and when the elasti...

  13. Revisiting Aggregation Techniques for Data Intensive Applications

    OpenAIRE

    Wen, Jian

    2013-01-01

    Aggregation has been an important operation since the early days of relational databases. Today's Big Data applications bring further challenges when processing aggregation queries, demanding robust aggregation algorithms that can process large volumes of data efficiently in a distributed, share-nothing architecture. Moreover, aggregation on each node runs under a potentially limited memory budget (especially in multiuser settings). Despite its importance, the design and evaluation of aggrega...

  14. Recycled aggregate concrete; an overview

    OpenAIRE

    Sorato, Renan

    2016-01-01

    The aim of this Bachelor’s thesis was to investigate whether recycled materials can be incorporated into the production of concrete without compromising the compressive strength of the concrete produced. In order to shed light on the compressive strength of concrete made from recycled materials, the thesis reviewed studies in which waste materials are utilised as recycled aggregates in the composition of concrete and presented the results of this synthesis and analysis. It was found that som...

  15. Intuitionistic fuzzy aggregation and clustering

    CERN Document Server

    Xu, Zeshui

    2012-01-01

    This book offers a systematic introduction to the clustering algorithms for intuitionistic fuzzy values, the latest research results in intuitionistic fuzzy aggregation techniques, the extended results in interval-valued intuitionistic fuzzy environments, and their applications in multi-attribute decision making, such as supply chain management, military system performance evaluation, project management, venture capital, information system selection, building materials classification, and operational plan assessment, etc.

  16. Economic Instability and Aggregate Investment

    OpenAIRE

    Robert S. Pindyck; Solimano, Andres

    1993-01-01

    Recent literature suggests that because investment expenditures are irreversible and can be delayed, they may be highly sensitive to uncertainty. The authors briefly summarize the theory, stressing its empirical implications. Then, using cross-section and time-series data for a set of developing and industrial countries, they explore the empirical relevance of irreversibility and uncertainty to aggregate investment. They find that: (a) the volatility of the marginal profitability of capital (...

  17. Belt conveyor for recycle aggregate

    OpenAIRE

    Bezrodný, Roman

    2014-01-01

    This bachelor thesis deals with the belt conveyor for the transport of recycled aggregate in an oblique direction. The aim is to find constructional solutions to the belt conveyor for the assigned transport capacity of 95 000 kg per hour, and the assigned axial distance of 49 m and different height of 12 m. The thesis contains a brief description of the belt conveyor and a description of basic constructional components. It also contains a functional calculation of the capacity and forces acco...

  18. Aggregating Labels in Crowdsourcing Data

    OpenAIRE

    Priisalu, Maria; Grey, Francois; Segal, Ben

    2015-01-01

    Project Specification Crowdsourcing is gaining popularity in academia with the launch of crowdsourcing platforms such as Crowdcrafting [Lombraña, 2015] and GeoTagX [UNOSAT, 2015]. There have been a number of proposed algorithms for the aggregation of true labels and a confusion matrix from crowdsourced labels for ordinal, nominal and binary labels. The work here consists of an implementation of the Dawid Skene [Dawid 1979] adaptation of the Expectation Maximization algorithm [D...

  19. Network Provisioning Using Multimedia Aggregates

    Directory of Open Access Journals (Sweden)

    Joan Vila-Carbó

    2008-01-01

    Full Text Available Multimedia traffic makes network provisioning a key issue. Optimal provisioning of network resources is crucial for reducing the service cost of multimedia transmission. Multimedia traffic requires not only provisioning bandwidth and buffer resources in the network but also guaranteeing a given maximum end-to-end delay. In this paper we present methods and tools for the optimal dimensioning of networks based on multimedia aggregates. The proposed method minimises the network resources reservations of traffic aggregates providing a bounded delay. The paper also introduces several methods to generate multimedia traffic aggregation using real video traces. The method is evaluated using a network topology based on the European GÉANT network. The results of these simulations allow us to discover the relationship between a required delay and the necessary bandwidth reservation (or the achievable utilisation limit. An interesting conclusion of these scenarios is that, following several recommendations, the network utilisation can reach values of around 80% or higher.

  20. Aggregated Authentication (AMAC) Using Universal Hash Functions

    Science.gov (United States)

    Znaidi, Wassim; Minier, Marine; Lauradoux, Cédric

    Aggregation is a very important issue to reduce the energy consumption in Wireless Sensors Networks (WSNs). There is currently a lack of cryptographic primitives for authentication of aggregated data. The theoretical background for Aggregated Message Authentication Codes (AMACs) has been proposed by Chan and Castelluccia at ISIT 08.

  1. An exact approach for aggregated formulations

    DEFF Research Database (Denmark)

    Gamst, Mette; Spoorendonk, Simon; Røpke, Stefan

    optimality cannot be guaranteed by branching on aggregated variables. We present a generic exact solution method to remedy the drawbacks of aggregation. It combines the original and aggregated formulations and applies Benders' decomposition. We apply the method to the Split Delivery Vehicle Routing Problem....

  2. Link Prediction in Complex Networks by Multi Degree Preferential-Attachment Indices

    CERN Document Server

    Hu, Ke; Yang, Wanchun; Xu, Xiaoke; Tang, Yi

    2012-01-01

    In principle, the rules of links formation of a network model can be considered as a kind of link prediction algorithm. By revisiting the preferential attachment mechanism for generating a scale-free network, here we propose a class of preferential attachment indices which are different from the previous one. Traditionally, the preferential attachment index is defined by the product of the related nodes degrees, while the new indices will define the similarity score of a pair of nodes by either the maximum in the two nodes degrees or the summarization of their degrees. Extensive experiments are carried out on fourteen real-world networks. Compared with the traditional preferential attachment index, the new ones, especially the degree-summarization similarity index, can provide more accurate prediction on most of the networks. Due to the improved prediction accuracy and low computational complexity, these proposed preferential attachment indices may be of help to provide an instruction for mining unknown links...

  3. Enantiomeric resolution of p-toluenesulfonate of valine benzyl ester by preferential crystallizaion.

    Science.gov (United States)

    Munegumi, Toratane; Wakatsuki, Aiko; Takahashi, Yutaro

    2012-02-01

    Preferential crystallization of amino acid derivatives by seeding a pure enantiomer into racemic amino acid solutions has been studied for many years. However, few examples of valine derivatives have been reported so far. Although there have been some reports using valine hydrogen chloride with preferential crystallization, it is difficult to obtain optical isomers for valine derivatives using preferential crystallization. In this study, repeated preferential crystallization of p-toluenesulfonate valine benzyl ester with a 20% e.e. in 2-propanol gave a 94% e.e. on sonication. Sonication accelerated crystallization rate, but there was not a big difference in e.e. between with and without sonication. However, this research demonstrates the first preferential crystallization of p-toluenesulfonate of valine benzyl esters with an acceleration of crystallization using sonication.

  4. An Empirical Investigation of Preferential Attachment Among Influential Members of a Large Artificial Community

    Directory of Open Access Journals (Sweden)

    JADERICK P. PABICO

    2014-02-01

    Full Text Available One among the many questions in social network analysis is how links form among members of Internet-mediated social network (ISN, where most members are usually anonymous, while link formation (i.e., interactions between members are facilitated only by non-personal communication technologies. Researchers offer preferential attachment (PA as a possible mechanism that can explain the behaviour of link formation, not only for real-world communities, but for artificial communities, such as ISNs, as well. PA suggests that members choose to be linked with members characterized with many links who are considered “central” to the community. This is because it is believed that central members can be relied to as a channel, if not the source themselves, of information, of wealth, or of any other kind of currency that the community is using. In this paper, the link formation process of members of one large ISN was examined to look for empirical evidences of PA among members who were clustered together according to the order of magnitude of their number of links at the global level. Members whose initial number of links that totals only up to ten thousand exhibit the opposite of PA, while members whose initial number of links that sums greater than ten thousand exhibit PA. This means that the lower bound for initial links for PA, at least for this particular ISN, is 10,000. Additionally, for those members whose link formation follow the PA mechanism, the order of magnitude of the rate of increase in their number of links is proportional to the order of magnitude of their initial number of links.

  5. Channel strategy adaptation

    OpenAIRE

    Rangan, V. Kasturi; Nueno, Jose L

    1999-01-01

    Using transaction cost theory, considerable research in marketing has focused on the conditions under which firms would use direct or vertically integrated versus indirect or arms length channels of distribution. Data from the field, however, indicate that channel configurations are more varied and complex, with multiple channels and composite channels being just as common as direct and indirect channels. In an attempt to explain this variety, this paper revisits the influence on channel stru...

  6. Government Policy and Aggregate Fluctuations Government Policy and Aggregate Fluctuations

    Directory of Open Access Journals (Sweden)

    Ellen R. McGrattan

    1991-03-01

    Full Text Available Government Policy and Aggregate Fluctuations This paper investigates the effect of including fiscal and monetary variables in a simple real business cycle model. The starting point is the stochastic growth model with fuctuations driven by technological shocks. The growth model is first extended to include government spending and taxes on factors of production. A second extension imposes a cash-in-advance constraint on purchases of consumption goods. For the three models, equilibrium decision functions and predictions for second moments are compared.

  7. Impact of asymmetrical flow field-flow fractionation on protein aggregates stability.

    Science.gov (United States)

    Bria, Carmen R M; Williams, S Kim Ratanathanawongs

    2016-09-23

    The impact of asymmetrical flow field-flow fractionation (AF4) on protein aggregate species is investigated with the aid of multiangle light scattering (MALS) and dynamic light scattering (DLS). The experimental parameters probed in this study include aggregate stability in different carrier liquids, shear stress (related to sample injection), sample concentration (during AF4 focusing), and sample dilution (during separation). Two anti-streptavidin (anti-SA) IgG1 samples composed of low and high molar mass (M) aggregates are subjected to different AF4 conditions. Aggregates suspended and separated in phosphate buffer are observed to dissociate almost entirely to monomer. However, aggregates in citric acid buffer are partially stable with dissociation to 25% and 5% monomer for the low and high M samples, respectively. These results demonstrate that different carrier liquids change the aggregate stability and low M aggregates can behave differently than their larger counterparts. Increasing the duration of the AF4 focusing step showed no significant changes in the percent monomer, percent aggregates, or the average Ms in either sample. Syringe-induced shear related to sample injection resulted in an increase in hydrodynamic diameter (dh) as measured by batch mode DLS. Finally, calculations showed that dilution during AF4 separation is significantly lower than in size exclusion chromatography with dilution occurring mainly at the AF4 channel outlet and not during the separation. This has important ramifications when analyzing aggregates that rapidly dissociate (theory may be more accurate than that measured by online DLS. Experimentally, the dhs determined by online DLS generally agreed with AF4 theory except for the more well retained larger aggregates for which DLS showed smaller sizes. These results highlight the importance of using AF4 retention theory to understand the impacts of dilution on analytes. PMID:27575921

  8. Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

    Directory of Open Access Journals (Sweden)

    Fér Miroslav

    2016-06-01

    Full Text Available The organo-mineral coatings of soil aggregates, cracks, and biopores control sorption and macropore-matrix exchange during preferential flow, in particular in the clay-illuvial Bt-horizon of Luvisols. The soil organic matter (SOM composition has been hypothesized to explain temporal changes in the hydraulic properties of aggregate surfaces. The objective of this research was to find relations between the temporal change in wettability, in terms of droplet infiltration dynamics, and the SOM composition of coated and uncoated aggregate surfaces. We used 20 to 40 mm sized soil aggregates from the Bt2 horizon of a Haplic Luvisol from loess that were (i coated, (ii not coated (both intact, and (iii aggregates from which coatings were removed (cut. The SOM composition of the aggregate surfaces was characterized by infrared spectroscopy in the diffuse reflection mode (DRIFT. A potential wettability index (PWI was calculated from the ratio of hydrophobic and hydrophilic functional groups in SOM. The water drop penetration times (WDPT and contact angles (CA during droplet infiltration experiments were determined on dry and moist aggregate samples of the three types. The decrease in the CA with time was described using the power function (CA(t = at−b. For dry aggregates, the WDPT values were larger for coated as compared to uncoated regions on the aggregate surfaces, and increased with increasing PWI value (R2 = 0.75. The a parameter was significantly related to the WDPT (R2 = 0.84 and to the PWI (R2 = 0.64. The relations between the b parameter and the WDPT (R2 = 0.61 and the PWI (R2 = 0.53 were also significant. The WDPT values of wet soil aggregates were higher than those of dry aggregates due to high water contents, which limited the droplet infiltration potential. At the wet aggregate surfaces, the WDPT values increased with the PWI of the SOM (R2 = 0.64. In contrast to dry samples, no significant relationships were found between parameters a or b

  9. Experimental study on separation of valuable refractory aggregate from investment casting ceramic shell waste

    Directory of Open Access Journals (Sweden)

    Ji-gao Li

    2016-07-01

    Full Text Available In the present study, a processing technique for recycling investment casting ceramic shell waste was proposed to separate valuable refractory aggregate zircon sand. The microstructure and phase constituents of the shell waste and separation process were investigated. The results show that the characteristics of microstructure and phase constituents of the shell waste can meet the conditions for preferentially separating zircon sand, and zircon sand can be separated by gravity separation on a shaking table. The separated zircon sand has good shape and high purity, and can be used for the production of castings and other applications.

  10. Topological Self-Similar Networks Introduced by Diffusion-Limited Aggregation Mechanism

    Institute of Scientific and Technical Information of China (English)

    YANG Lei; PEI Wen-Jiang; LI Tao; CHEUNG Yiu-Ming; HE Zhen-Ya

    2008-01-01

    @@ We propose a model for growing fractal networks based on the mechanisms learned from the diffusion-limited aggregation (DLA) model in fractal geometries in the viewpoint of network.By studying the DLA network,our model introduces multiplicative growth,aging and geographical preferential attachment mechanisms,whereby featuring topological self-similar property and hierarchical modularity.According to the results of theoretical analysis and simulation,the degree distribution of the proposed model shows a mixed degree distribution (i.e.,exponential and algebraic degree distribution) and the fractal dimension and clustering coefficient can be tuned by changing the values of parameters.

  11. Aggregation of Diesel Contaminated Soil for Bioremediation

    Institute of Scientific and Technical Information of China (English)

    Yu Ying; Shi Xiu-hong; Li Song; Xu Jing-gang

    2014-01-01

    Diesel contaminated soil (DCS) contained a large amount of the hydrocarbons and salt which was dominated by soluble sodium chloride. Aggregation process which made the desired aggregate size distribution could speed up the degradation rate of the hydrocarbons since the aggregated DCS had better physical characteristics than the non-aggregated material. Artificial aggregation increased pores >30 µm by approximately 5% and reduced pores <1 µm by 5%, but did not change the percentage of the pores between 1 and 30 µm. The saturated hydraulic conductivity of non-aggregated DCS was 5×10-6 m• s-l, but it increased to 1×10-5 m• s-l after aggregation. The compression index of the non-aggregated DCS was 0.0186; however, the artificial aggregates with and without lime were 0.031 and 0.028, respectively. DCS could be piled 0.2 m deep without artificial aggregation; however, it could be applied 0.28 m deep when artificial aggregates were formed without limiting O2 transport.

  12. Microwave extinction characteristics of nanoparticle aggregates

    Science.gov (United States)

    Wu, Y. P.; Cheng, J. X.; Liu, X. X.; Wang, H. X.; Zhao, F. T.; Wen, W. W.

    2016-07-01

    Structure of nanoparticle aggregates plays an important role in microwave extinction capacity. The diffusion-limited aggregation model (DLA) for fractal growth is utilized to explore the possible structures of nanoparticle aggregates by computer simulation. Based on the discrete dipole approximation (DDA) method, the microwave extinction performance by different nano-carborundum aggregates is numerically analyzed. The effects of the particle quantity, original diameter, fractal structure, as well as orientation on microwave extinction are investigated, and also the extinction characteristics of aggregates are compared with the spherical nanoparticle in the same volume. Numerical results give out that proper aggregation of nanoparticle is beneficial to microwave extinction capacity, and the microwave extinction cross section by aggregated granules is better than that of the spherical solid one in the same volume.

  13. Bouncing Behavior of Microscopic Dust Aggregates

    CERN Document Server

    Seizinger, Alexander

    2013-01-01

    Context: Bouncing collisions of dust aggregates within the protoplanetary may have a significant impact on the growth process of planetesimals. Yet, the conditions that result in bouncing are not very well understood. Existing simulations studying the bouncing behavior used aggregates with an artificial, very regular internal structure. Aims: Here, we study the bouncing behavior of sub-mm dust aggregates that are constructed applying different sample preparation methods. We analyze how the internal structure of the aggregate alters the collisional outcome and determine the influence of aggregate size, porosity, collision velocity, and impact parameter. Methods: We use molecular dynamics simulations where the individual aggregates are treated as spheres that are made up of several hundred thousand individual monomers. The simulations are run on GPUs. Results: Statistical bulk properties and thus bouncing behavior of sub-mm dust aggregates depend heavily on the preparation method. In particular, there is no uni...

  14. Predictions for particle deposition from LES of ribbed channel flow

    International Nuclear Information System (INIS)

    Predictions for the deposition of spherical and cylindrical particles from a ribbed channel flow onto adjacent flow boundaries are obtained using large eddy simulation (LES) under the assumption of one-way coupling. Results indicate that spherical particles tend to accumulate on the vertical rib wall facing the mean-flow direction with little particle deposition onto surfaces immediately downstream of the rib. This preferential deposition is not predicted for cylindrical particles

  15. Quantifying the Preferential Flow by Dye Tracer in the North China Plain

    Institute of Scientific and Technical Information of China (English)

    Qinghua Wu; Chunlei Liu; Wenjing Lin; Meng Zhang; Guiling Wang; Fawang Zhang

    2015-01-01

    The preferential flow plays a vital role on the infiltration of irrigation or rainfall. The ob-jective of this study was to quantify preferential flow in the processing of irrigation infiltration in the field scale. Tests of different initial soil water contents and irrigation intensities were conducted using Brilliant Blue FCF (C.I.42090) dye tracer in Luancheng County of the North China Plain. The results showed that the percentages of infiltration by the preferential flow for irrigation depth of 25, 50, and 75 mm were 16.67%, 43.67%, and 34.17%, with 19.72%, 61.42%, 66.64%of dyed areas in the soil profile, respectively, which indicated that preferential flow was enhanced with increasing irrigation intensity, but reduced when the irrigation intensity was over 50 mm. The percentages of preferential flow for 75 and 180 mm previous irrigation producing different initial soil water contents were 23.26%and 18.97%, with 53.23% and 39.94% of dyed areas in the soil profile, respectively. Compared with the 75 mm without previous irrigation, the results indicated that higher initial soil water contents restrained the preferential flow in the field. Therefore, intermittent irrigation and low irrigation intensity patterns, and larger depth of plowing would be suggested to reduce the preferential flow which would increase the soil water utilization efficiency and reduce pollution risk of pesticide and fertilizer to groundwater.

  16. PERCOLATION OF RANDOM CYLINDER AGGREGATES

    Directory of Open Access Journals (Sweden)

    Dominique Jeulin

    2011-05-01

    Full Text Available The percolation threshold ρc of Boolean models of cylinders with their axis parallel to a given direction is studied by means of simulations. An efficient method of construction of percolating connected components was developed, and is applied to one or two scales Boolean model, in order to simulate the presence of aggregates. The invariance of the percolation threshold with respect to affine transformations in the common direction of the axis of cylinders is approximately satisfied on simulations. The prediction of the model (ρc close to 0.16 is consistent with experimental measurements on plasma spray coatings, which motivated this study.

  17. Inhomogeneous diffusion-limited aggregation

    Science.gov (United States)

    Selinger, Robin Blumberg; Nittmann, Johann; Stanley, H. E.

    1989-01-01

    It is demonstrated here that inhomogeneous diffusion-limited aggregation (DLA) model can be used to simulate viscous fingering in a medium with inhomogeneous permeability and homogeneous porosity. The medium consists of a pipe-pore square-lattice network in which all pores have equal volume and the pipes have negligible volume. It is shown that fluctuations in a DLA-based growth process may be tuned by noise reduction, and that fluctuations in the velocity of the moving interface are multiplicative in form.

  18. Credit, Money, and Aggregate Demand

    OpenAIRE

    Bernanke, Ben S.; Alan S. Blinder

    1988-01-01

    Standard models of aggregate demand treat money and credit asymmetrically; money is given a special status, while loans, bonds, and other debt instruments are lumped together in a "bond market" and suppressed by Walras' Law. This makes bank liabilities central to the monetary transmission mechanism, while giving no role to bank assets. We show how to modify a textbook IS-UI model so as to permit a more balanced treatment. As in Tobin (1969) and Brunner-Meltzer (1972), the key assumption is th...

  19. Logically Sensing Aggregate Process and Discriminating SDS from Other Surfactants with the Assistance of BSA

    Institute of Scientific and Technical Information of China (English)

    钱俊红; 徐玉芳; 钱旭红

    2012-01-01

    An amphiphilic fluorescent probe, 3-dodecylamino dihydrogen imidazo[2,l-a]benz[de]isoquinolin-7-one (compound 3), was used to sense the aggregate formation process of bovine serum albumine (BSA), sodium dode- cyl sulfate (SDS) and their mixed system. The fluorescence intensity of 3 was significantly affected by the adding order of SDS and BSA, and SDS can be distinguished from other surfactants with the aid of BSA, but only when 3 is allowed to interact with BSA first. The results revealed that compound 3 is preferentially sited in the hydrophobic region of BSA, and thermodynamically in SDS-BSA mixed aggregate. Sodium phosphate buffer solution (PBS) and BSA played important but distinct roles in distinguishing SDS micelle from the others.

  20. Spatial and temporal occurrence of preferential flow in a forested headwater catchment

    Science.gov (United States)

    Wiekenkamp, I.; Huisman, J. A.; Bogena, H. R.; Lin, H. S.; Vereecken, H.

    2016-03-01

    The highly dynamic nature of preferential flow in time and space makes it challenging to identify and analyze its occurrence at the catchment scale. Novel analysis methods using soil moisture sensor response times offer an opportunity to investigate catchment-wide controls on preferential flow. The aim of this study was to identify factors that control preferential flow occurrence based on 3-year soil moisture monitoring using a wireless sensor network in the Wüstebach catchment, Germany. At 101 locations, the sensor response times at three depths (5, 20, and 50 cm) were classified into one of four classes: (1) non-sequential preferential flow, (2) velocity-based preferential flow, (3) sequential flow, and (4) no response. A conceptual model, postulating that preferential flow in the Wüstebach catchment is dominated by differences in soil type, landscape position, and rainfall input, was proposed for hypothesis testing. To test the conceptual model, the classification results were combined with spatial and event-based data to understand and identify controlling factors. Spatial parameters consisted of hydrological, topographical, and soil physical and chemical parameters. Temporal factors included precipitation characteristics and antecedent soil moisture conditions. The conceptual model as proposed could only be partly confirmed. Event-based occurrence of preferential flow was highly affected by precipitation amount, with a nearly catchment-wide preferential response during large storm events. During intermediate events, preferential flow was controlled by small-scale heterogeneity, instead of showing catchment-wide patterns. The effect of antecedent catchment wetness on the occurrence of preferential flow was generally less profound, although a clear negative relationship was found for precipitation events with more than 25 mm. It was found that spatial occurrence of preferential flow was however governed by small-scale soil and biological features and local

  1. Predicting the growth of new links by new preferential attachment similarity indices

    Indian Academy of Sciences (India)

    Ke Hu; Ju Xiang; Xiao-Ke Xu; Hui-Jia Li; Wan-Chun Yang; Yi Tang

    2014-03-01

    By revisiting the preferential attachment (PA) mechanism for generating a classical scale-free network, we propose a class of novel preferential attachment similarity indices for predicting future links in evolving networks. Extensive experiments on 14 real-life networks show that these new indices can provide more accurate prediction than the traditional one. Due to the improved prediction accuracy and low computational complexity, these proposed preferential attachment indices can be helpful for providing both instructions for mining unknown links and new insights to understand the underlying mechanisms that drive the network evolution.

  2. Mobile radio channels

    CERN Document Server

    Pätzold, Matthias

    2011-01-01

    Providing a comprehensive overview of the modelling, analysis and simulation of mobile radio channels, this book gives a detailed understanding of fundamental issues and examines state-of-the-art techniques in mobile radio channel modelling. It analyses several mobile fading channels, including terrestrial and satellite flat-fading channels, various types of wideband channels and advanced MIMO channels, providing a fundamental understanding of the issues currently being investigated in the field. Important classes of narrowband, wideband, and space-time wireless channels are explored in deta

  3. Estimating Aggregate Demand in Egypt

    Directory of Open Access Journals (Sweden)

    Noha EMARA

    2016-03-01

    Full Text Available Abstract. This econometric study seeks to determine the most important factors of aggregate demand in Egypt so as to provide insight into how this developing nation can grow economically in the coming years. The Ordinary Least Squares estimation method was used in order to estimate nominal GDP for the time period 1975 to 2009. Based on the results the real interest rate, the inflation rate, the growth rate of government expenditure, and the growth rate of the money supply are the most statistically and economically significant factors of the growth rate of nominal GDP for the coming year. A one percent change in the growth rate of the previous year government expenditure is predicted to cause the growth rate of the current year nominal GDP to increase by 54%.The role of government expenditures on public sector wage expansion is discussed in this study as to shed light on this factor’s significant influence on income inequality post-1975 in Egypt, which will continue to impact nominal GDP and social conditions for the developing nation in the coming years.Keywords. GDP, Aggregate Demand, Egypt.JEL. E25, O40, Q11.

  4. Evolution of pyrrhotite oxidation in aggregates for concrete

    Directory of Open Access Journals (Sweden)

    Oliveira, I.

    2014-12-01

    Full Text Available Rocks containing pyrrhotite bands are sometimes used to produce concrete. These rocks oxidize and produce long-term expansive reactions that damage concrete structures, leading to important economic and risk related repercussions. The present study analyses several aspects that affect the oxidation process of the aggregate such as the existence of preferential paths for the entrance of the oxidizing agent and the conversion process of the chemical elements involved in the reaction. For that, host rock samples containing pyrrhotite were investigated by scanning electron microscopy and energy dispersive spectroscopy. The results shows that the pyrrhotite appears in bands that create planes of weakness and present cracks that serve as preferential paths for the entrance of oxygen. Furthermore, a new representation is proposed for the oxidation process.Rocas con bandas de pirrotina han sido usadas para producir áridos destinados a la fabricación de hormigones. Las mismas son susceptible a un fenómeno de oxidación que a largo plazo produce la degradación del material, llevando a importantes repercusiones económica y en cuanto a la seguridad. El presente estudio evalúa la influencia de diferentes aspectos que pueden afectar dicho proceso de oxidación del agregado, tales como la existencia de caminos preferentes para la entrada del agente oxidante y los elementos químicos involucrados en la reacción. Para ello, muestras de roca con pirrotina han sido analizadas mediante microscopía electrónica de barrido. Los resultados indican que la pirrotina aparece en bandas que dan lugar a planos de debilidad y fisuración. Esas fisuras actúan como caminos preferentes a la entrada del oxígeno. Asimismo, con base en los análisis realizados se ha propuesto una nueva representación para el proceso de oxidación.

  5. Utilization Possibility of Natural Aggregate Resources in Central Town of Tokat as Concrete Aggregate

    Directory of Open Access Journals (Sweden)

    S. I. Tutmaz

    2010-01-01

    Full Text Available In this study, aggregates of three quarries sampled from Tokat Province were tested to evaluate their suitability for concrete production. The aggregates were supplied from Yesilirmak River, and largely used in agricultural structures constructed in Tokat. Standard aggregate tests approved by Turkish Standards Institute were carried out to analyze the samples. Granulation, unit weight, specific weight, water absorption rate, resistance to frost, resistance against abrasion, ratio of fine materials, organic material contents and, mineralogical analysis of aggregates sampled from aggregate quarries were determined. Pressure resistance tests were conducted on concrete prepared by the aggregates. The results indicated that the aggregate granulation distribution of aggregate quarries evaluated was not suitable however other parameters determined were appropriate for concrete production. The resultant concrete had sufficient pressure resistance. The possible solutions to improve the improper characteristics of aggregates used in concrete were also determined and introduced with this study.

  6. Asphaltene Aggregation and Fouling Behavior

    Science.gov (United States)

    Derakhshesh, Marzie

    This thesis explored the properties of asphaltene nano-aggregates in crude oil and toluene based solutions and fouling at process furnace temperatures, and the links between these two phenomena. The link between stability of asphaltenes at ambient conditions and fouling at the conditions of a delayed coker furnace, at over 450 °C, was examined by blending crude oil with an aliphatic diluent in different ratios. The stability of the blends were measured using a S-value analyzer, then fouling rates were measured on electrically heated stainless steel 316 wires in an autoclave reactor. The less stable the blend, the greater the rate and extent of fouling. The most severe fouling occurred with the unstable asphaltenes. SEM imaging of the foulant illustrates very different textures, with the structure becoming more porous with lower stability. Under cross-polarized light, the coke shows the presence of mesophase in the foulant layer. These data suggest a correlation between the fouling rate at high temperature furnace conditions and the stability index of the crude oil. Three organic polysulfides were introduced to the crude oil to examine their effect on fouling. The polysulfides are able to reduce coking and carbon monoxide generation in steam crackers. The fouling results demonstrated that polysulfide with more sulfur content increased the amount of corrosion-fouling of the wire. Various additives, solvents, ultrasound, and heat were employed to attempt to completely disaggregate the asphaltene nano-aggregates in solution at room temperature. The primary analytical technique used to monitor the nano-aggregation state of the asphaltenes in solution was the UV-visible spectroscopy. The results indicate that stronger solvents, such as pyridine and quinoline, combined with ionic liquids yield a slight reduction in the apparent absorbance at longer wavelengths, indicative of a decrease in the nano-aggregate size although the magnitude of the decrease is not significant

  7. Channel nut tool

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Marvin

    2016-01-12

    A method, system, and apparatus for installing channel nuts includes a shank, a handle formed on a first end of a shank, and an end piece with a threaded shaft configured to receive a channel nut formed on the second end of the shaft. The tool can be used to insert or remove a channel nut in a channel framing system and then removed from the channel nut.

  8. Self-aggregation properties of spin-labeled zervamicin IIA as studied by PELDOR spectroscopy.

    Science.gov (United States)

    Milov, A D; Tsvetkov, Yu D; Gorbunova, E Yu; Mustaeva, L G; Ovchinnikova, T V; Raap, J

    2002-09-01

    In this article, the pulsed double electron-electron resonance in electron spin-echo (PELDOR) technique is applied to study the self-aggregation of spin-labeled zervamicin IIA, a hexadecapeptide antibiotic of fungal origin, which is known to form ion channels in a phospholipid double layer. Measurements of the ion channel forming properties and the antibiotic activity of the analog indicate that replacement of the C-terminal phenylalaninol by the amino-2,2,6,6-tetramethylpiperidinyloxy (TEMPO) residue does not influence the biophysical and biological properties. The dipole-dipole interaction between the spin labels of the fully biologically active peptide analog was studied in frozen (77 K) glassy solutions in different ratios of toluene-methanol. The spin-labeled zervamicin IIA molecules were shown to form aggregates. An average distance between the spin labels in the aggregates was estimated to be in the range of 25-35 A (depending on the solvent composition), indicating that the amphiphilic helical peptide molecules are oriented in an antiparallel fashion. Increasing of methanol content in the solution results in a loosening of the aggregate structure. It was shown that the fraction of aggregated zervamicin IIA molecules is less than 44-67% depending on the solvent composition. The general usefulness of the method to obtain structural long-range information in a range of several tens of angstroms is demonstrated by comparison with the peptide cluster of trichogin GA IV. PMID:12124850

  9. A novel interactive preferential evolutionary method for controller tuning in chemical processes☆

    Institute of Scientific and Technical Information of China (English)

    Chong Su; Hongguang Li

    2015-01-01

    In response to many multi-attribute decision-making (MADM) problems involved in chemical processes such as controller tuning, which suffer human's subjective preferential nature in human–computer interactions, a novel affective computing and preferential evolutionary solution is proposed to adapt human–computer interaction mechanism. Based on the stimulating response mechanism, an improved affective computing model is intro-duced to quantify decision maker's preference in selections of interactive evolutionary computing. In addition, the mathematical relationship between affective space and decision maker's preferences is constructed. Subse-quently, a human–computer interactive preferential evolutionary algorithm for MADM problems is proposed, which deals with attribute weights and optimal solutions based on preferential evolution metrics. To exemplify applications of the proposed methods, some test functions and, emphatical y, control er tuning issues associated with a chemical process are investigated, giving satisfactory results.

  10. A macroscopic relationship for preferential flow in the vadose zone: Theory and Validation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H.H.; Zhang, R.D.

    2010-02-15

    Preferential flow commonly observed in unsaturated soils allows rapid movement of solute from the ground surface or vadose zone to the groundwater, bypassing a significant volume of unsaturated soil and increasing the risk of groundwater contamination. A variety of evidence indicates that complex preferential flow patterns observed from fields are fractals. This paper discusses a macroscopic rela-tionship for modeling preferential flow in the vadose zone. Conceptually, the flow domain can be di-vided into active and inactive regions. Flow occurs preferentially in the active region (characterized by fractals), and inactive region is simply bypassed. The portion of the active region was found to be a power function of saturation. The validity of this macroscopic relationship is demonstrated by its consistency with field observations and the related numerical experiments.

  11. Macroscopic relationship for preferential flow in the vadose zone: Theory and validation

    Institute of Scientific and Technical Information of China (English)

    LIU HuiHai; ZHANG RenDuo

    2009-01-01

    Preferential flow commonly observed in unsaturated soils allows rapid movement of solute from the ground surface or vadose zone to the groundwater, bypassing a significant volume of unsaturated soil and increasing the risk of groundwater contamination.A variety of evidence indicates that complex preferential flow patterns observed from fields are fractals.This paper discusses a macroscopic rela-tionship for modeling preferential flow in the vadose zone.Conceptually, the flow domain can be di-vided into active and inactive regions.Flow occurs preferentially in the active region (characterized by fractals), and inactive region is simply bypassed.The portion of the active region was found to be a power function of saturation.The validity of this macroscopic relationship is demonstrated by its con-sistency with field observations and the related numerical experiments.

  12. Growth of Preferential Attachment Random Graphs Via Continuous-Time Branching Processes

    Indian Academy of Sciences (India)

    Krishna B Athreya; Arka P Ghosh; Sunder Sethuraman

    2008-08-01

    Some growth asymptotics of a version of `preferential attachment’ random graphs are studied through an embedding into a continuous-time branching scheme. These results complement and extend previous work in the literature.

  13. Effects of soil compaction and organic carbon content on preferential flow in loamy field soils

    DEFF Research Database (Denmark)

    Soares, Antonio; Møldrup, Per; Vendelboe, Anders Lindblad;

    2015-01-01

    © 2015 Wolters Kluwer Health, Inc. Preferential flowand transport throughmacropores affect plant water use efficiency and enhance leaching of agrochemicals and the transport of colloids, thereby increasing the risk for contamination of groundwater resources. The effects of soil compaction...

  14. Macroscopic relationship for preferential flow in the vadose zone:Theory and validation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Preferential flow commonly observed in unsaturated soils allows rapid movement of solute from the ground surface or vadose zone to the groundwater, bypassing a significant volume of unsaturated soil and increasing the risk of groundwater contamination. A variety of evidence indicates that complex preferential flow patterns observed from fields are fractals. This paper discusses a macroscopic relationship for modeling preferential flow in the vadose zone. Conceptually, the flow domain can be divided into active and inactive regions. Flow occurs preferentially in the active region (characterized by fractals), and inactive region is simply bypassed. The portion of the active region was found to be a power function of saturation. The validity of this macroscopic relationship is demonstrated by its consistency with field observations and the related numerical experiments.

  15. One-dimensional long-range diffusion-limited aggregation III -- The limit aggregate

    CERN Document Server

    Amir, Gideon

    2009-01-01

    In this paper we study the structure of the limit aggregate (the union of all finite-time aggregates) of the one-dimensional long range diffusion limited aggregation process defined in [arXiv:0910.4416] . We show (under some regularity conditions) that for walks with finite third moment the limit aggregate has renewal structure and positive density, while for walks with finite variance the renewal structure no longer exists and the limit aggregate has 0 density. We define a tree structure on the aggregates and show some results on the degrees and number of ends of these random trees.

  16. Aggregation and fibrillation of bovine serum albumin

    DEFF Research Database (Denmark)

    Holm, NK; Jespersen, SK; Thomassen, LV;

    2007-01-01

    The all-alpha helix multi-domain protein bovine serum albumin (BSA) aggregates at elevated temperatures. Here we show that these thermal aggregates have amyloid properties. They bind the fibril-specific dyes Thioflavin T and Congo Red, show elongated although somewhat worm-like morphology...... and changes in morphology suggest the existence of different aggregate species. Although beta-sheet content increases from 0 to ca. 40% upon aggregation, the aggregates retain significant amounts of alpha-helix structure, and lack a protease-resistant core. Thus BSA is able to form well-ordered beta...... significant amounts of alpha-helix, highlights the universality of the fibrillation mechanism. However, the presence of non-beta-sheet structure may influence the final fibrillar structure and could be a key component in aggregated BSA's lack of cytotoxicity....

  17. A dimension map for molecular aggregates.

    Science.gov (United States)

    Jian, Cuiying; Tang, Tian; Bhattacharjee, Subir

    2015-05-01

    A pair of gyradius ratios, defined from the principal radii of gyration, are used to generate a dimension map that describes the geometry of molecular aggregates in water and in organic solvents. Molecular dynamics simulations were performed on the aggregation of representative biomolecules and polyaromatic compounds to demonstrate application of the dimension map. It was shown that molecular aggregate data on the dimension map were bounded by two boundary curves, and that the map could be separated into three regions representing three groups of structures: one-dimensional rod-like structures; two-dimensional planar structures or short-cylinder-like structures; and three-dimensional sphere-like structures. Examining the location of the aggregates on the dimension map and how the location changes with solvent type and solute material parameter provides a simple yet effective way to infer the aggregation manner and to study solubility and mechanism of aggregation. PMID:25768393

  18. A vertically resolved model for phytoplankton aggregation

    Indian Academy of Sciences (India)

    Iris Kriest; Geoffrey T Evans

    2000-12-01

    This work presents models of the vertical distribution and flux of phytoplankton aggregates, including changes with time in the distribution of aggregate sizes and sinking speeds. The distribution of sizes is described by two parameters, the mass and number of aggregates, which greatly reduces the computational cost of the models. Simple experiments demonstrate the effects of aggregation on the timing and depth distribution of primary production and export. A more detailed ecological model is applied to sites in the Arabian Sea; it demonstrates that aggregation can be important for deep sedimentation even when its effect on surface concentrations is small, and it presents the difference in timing between settlement of aggregates and fecal pellets.

  19. Aggregation server for grid-integrated vehicles

    Science.gov (United States)

    Kempton, Willett

    2015-05-26

    Methods, systems, and apparatus for aggregating electric power flow between an electric grid and electric vehicles are disclosed. An apparatus for aggregating power flow may include a memory and a processor coupled to the memory to receive electric vehicle equipment (EVE) attributes from a plurality of EVEs, aggregate EVE attributes, predict total available capacity based on the EVE attributes, and dispatch at least a portion of the total available capacity to the grid. Power flow may be aggregated by receiving EVE operational parameters from each EVE, aggregating the received EVE operational parameters, predicting total available capacity based on the aggregated EVE operational parameters, and dispatching at least a portion of the total available capacity to the grid.

  20. Small molecule proteostasis regulators that reprogram the ER to reduce extracellular protein aggregation

    Science.gov (United States)

    Plate, Lars; Cooley, Christina B; Chen, John J; Paxman, Ryan J; Gallagher, Ciara M; Madoux, Franck; Genereux, Joseph C; Dobbs, Wesley; Garza, Dan; Spicer, Timothy P; Scampavia, Louis; Brown, Steven J; Rosen, Hugh; Powers, Evan T; Walter, Peter; Hodder, Peter; Wiseman, R Luke; Kelly, Jeffery W

    2016-01-01

    Imbalances in endoplasmic reticulum (ER) proteostasis are associated with etiologically-diverse degenerative diseases linked to excessive extracellular protein misfolding and aggregation. Reprogramming of the ER proteostasis environment through genetic activation of the Unfolded Protein Response (UPR)-associated transcription factor ATF6 attenuates secretion and extracellular aggregation of amyloidogenic proteins. Here, we employed a screening approach that included complementary arm-specific UPR reporters and medium-throughput transcriptional profiling to identify non-toxic small molecules that phenocopy the ATF6-mediated reprogramming of the ER proteostasis environment. The ER reprogramming afforded by our molecules requires activation of endogenous ATF6 and occurs independent of global ER stress. Furthermore, our molecules phenocopy the ability of genetic ATF6 activation to selectively reduce secretion and extracellular aggregation of amyloidogenic proteins. These results show that small molecule-dependent ER reprogramming, achieved through preferential activation of the ATF6 transcriptional program, is a promising strategy to ameliorate imbalances in ER function associated with degenerative protein aggregation diseases. DOI: http://dx.doi.org/10.7554/eLife.15550.001 PMID:27435961

  1. Global preferential consistency for the topological sorting-based maximal spanning tree problem

    CERN Document Server

    Joseph, Rémy-Robert

    2012-01-01

    We introduce a new type of fully computable problems, for DSS dedicated to maximal spanning tree problems, based on deduction and choice: preferential consistency problems. To show its interest, we describe a new compact representation of preferences specific to spanning trees, identifying an efficient maximal spanning tree sub-problem. Next, we compare this problem with the Pareto-based multiobjective one. And at last, we propose an efficient algorithm solving the associated preferential consistency problem.

  2. Preferential Cattle and Hog Pricing by Packers: Evidence from Mandatory Price Reports

    OpenAIRE

    Ward, Clement E.

    2008-01-01

    Preferential pricing was one of several concerns leading to mandatory price reporting. Seven years of “new” data from mandatory reports are examined to determine if evidence exists of preferential pricing by packers for fed cattle and slaughter hogs. Weekly data show some alternative marketing methods track closer to cash market prices than others. Some differences can be explained, while others are not as clear. Evidence was found that cash prices lead prices for alternative marketing method...

  3. A promoter that drives gene expression preferentially in male transgenic rats

    OpenAIRE

    Li, Qiling; Ma, Yamin; Li, Wenzhi; Xu, Wei; Ma, Li; Fu, Guoxing; Tian, Xiaohua; Wang, Yueling; Li, Xu; Bythwood, Tameka; Richards, Jendai; Song, Qing

    2013-01-01

    Gender-preferential gene expression is a widespread phenomenon in humans. It is important to study how gender differences influence the pathogenesis of various diseases and response to specific drugs. The aim of this study is to determine if the mouse albumin enhancer/promoter may serve as the promoter to introduce gender-preferential gene expression in transgenic animals. We created four independent transgenic rat lines in which the human C-reactive protein (CRP) transgene was under the cont...

  4. Which key properties controls the preferential transport in the vadose zone under transient hydrological conditions

    Science.gov (United States)

    Groh, J.; Vanderborght, J.; Puetz, T.; Gerke, H. H.; Rupp, H.; Wollschlaeger, U.; Stumpp, C.; Priesack, E.; Vereecken, H.

    2015-12-01

    Understanding water flow and solute transport in the unsaturated zone is of great importance for an appropriate land use management strategy. The quantification and prediction of water and solute fluxes through the vadose zone can help to improve management practices in order to limit potential risk on our fresh water resources. Water related solute transport and residence time is strongly affected by preferential flow paths in the soil. Water flow in soils depends on soil properties and site factors (climate or experiment conditions, land use) and are therefore important factors to understand preferential solute transport in the unsaturated zone. However our understanding and knowledge of which on-site properties or conditions define and enhance preferential flow and transport is still poor and mostly limited onto laboratory experimental conditions (small column length and steady state boundary conditions). Within the TERENO SOILCan lysimeter network, which was designed to study the effects of climate change on soil functions, a bromide tracer was applied on 62 lysimeter at eight different test sites between Dec. 2013 and Jan. 2014. The TERENO SOILCan infrastructure offers the unique possibility to study the occurrence of preferential flow and transport of various soil types under different natural transient hydrological conditions and land use (crop, bare and grassland) at eight TERENO SOILCan observatories. Working with lysimeter replicates at each observatory allows defining the spatial variability of preferential transport and flow. Additionally lysimeters in the network were transferred within and between observatories in order to subject them to different rainfall and temperature regimes and enable us to relate the soil type susceptibility of preferential flow and transport not only to site specific physical and land use properties, but also to different transient boundary conditions. Comparison and statistical analysis between preferential flow indicators 5

  5. New Zealand's Preferential Trading Arrangements: Implications for the New Zealand Dairy Industry

    OpenAIRE

    Howard, Sam; Gow, Hamish R.; Ozer-Balli, Hatice

    2011-01-01

    This paper discusses the economic implications of the preferential trade agreements that New Zealand is currently negotiating, using a computable general equilibrium modelling framework. The New Zealand dairy industry is a particular focus in the results, which come from the GTAP model produced by Purdue University. Results are discussed from the independent simulations of preferential trade agreements between New Zealand and Korea, New Zealand and India, New Zealand and Russia, Belarus and K...

  6. Quantification of the influence of preferential flow on slope stability using a numerical modeling approach

    Directory of Open Access Journals (Sweden)

    W. Shao

    2014-11-01

    Full Text Available The effect of preferential flow on the stability of landslides is studied through numerical simulation of two types of rainfall events on a hypothetical hillslope. A model is developed that consists of two parts. The first part is a model for combined saturated/unsaturated subsurface flow and is used to compute the spatial and temporal water pressure response to rainfall. Preferential flow is simulated with a dual-permeability continuum model consisting of a matrix domain coupled to a preferential flow domain. The second part is a~soil mechanics model and is used to compute the spatial and temporal distribution of the local factor of safety based on the water pressure distribution computed with the subsurface flow model. Two types of rainfall events were considered: long duration, low-intensity rainfall, and short duration, high-intensity rainfall. The effect of preferential flow on slope stability is assessed through comparison of the failure area when subsurface flow is simulated with the dual-permeability model as compared to a single-permeability model (no preferential flow. For the low-intensity rainfall case, preferential flow has a positive effect on the slope stability as it drains the water from the matrix domain resulting in a smaller failure area. For the high-intensity rainfall case, preferential flow has a negative effect on the slope stability as the majority of rainfall infiltrates into the preferential flow domain when rainfall intensity exceeds the infiltration capacity of the matrix domain, resulting in larger water pressure and a larger failure area.

  7. Quantification of the influence of preferential flow on slope stability using a numerical modeling approach (discussions)

    OpenAIRE

    Shao, W.; Bogaard, T.A.; M. Bakker; R. Greco

    2014-01-01

    The effect of preferential flow on the stability of landslides is studied through numerical simulation of two types of rainfall events on a hypothetical hillslope. A model is developed that consists of two parts. The first part is a model for combined saturated/unsaturated subsurface flow and is used to compute the spatial and temporal water pressure response to rainfall. Preferential flow is simulated with a dual-permeability continuum model consisting of a matrix domain coupled to a prefere...

  8. Quantification of the influence of preferential flow on slope stability using a numerical modelling approach

    OpenAIRE

    Shao, W.; Bogaard, T.A.; M. Bakker; R. Greco

    2015-01-01

    The effect of preferential flow on the stability of landslides is studied through numerical simulation of two types of rainfall events on a hypothetical hillslope. A model is developed that consists of two parts. The first part is a model for combined saturated/unsaturated subsurface flow and is used to compute the spatial and temporal water pressure response to rainfall. Preferential flow is simulated with a dual-permeability continuum model consisting of a matrix do...

  9. Chloride channels of platelets%血小板氯通道

    Institute of Scientific and Technical Information of China (English)

    陈晓琳; 尹松梅

    2004-01-01

    Chloride channels distribute widely in the body, and participate in many physiological actions and regulatory processes. Based on their physiological roles and molecular structures, six kinds of chloride channels have been identified: (1) The chloride channels family; (2) Cystic fibrosis transmembrane conductance regulator; (3) Swelling-activated chloride channels; (4) Calcium-activated chloride channels; (5) The p64 (CLIC) gene family; (6) γ-aminobutyric acid and glycine receptors. The chloride channels do exist in platelets, and their appearances are dependent on the presence of intracellular calcium. Blocking agents of chloride channels inhibit the thrombin-activated platelet aggregation and the elevation of the intracellular calcium concentration in a dose-dependent manner. It is suggested that chloride channels play a role in the activation of platelets. In addition, chloride channels act on both the cell volume regulation and the intracellular pH regulation in platelets.

  10. Simulations of kinetically irreversible protein aggregate structure.

    OpenAIRE

    Patro, S Y; Przybycien, T M

    1994-01-01

    We have simulated the structure of kinetically irreversible protein aggregates in two-dimensional space using a lattice-based Monte-Carlo routine. Our model specifically accounts for the intermolecular interactions between hydrophobic and hydrophilic protein surfaces and a polar solvent. The simulations provide information about the aggregate density, the types of inter-monomer contacts and solvent content within the aggregates, the type and extent of solvent exposed perimeter, and the short-...

  11. Diffusion Limited Aggregation: Algorithm optimization revisited

    Science.gov (United States)

    Braga, F. L.; Ribeiro, M. S.

    2011-08-01

    The Diffusion Limited Aggregation (DLA) model developed by Witten and Sander in 1978 is useful in modeling a large class of growth phenomena with local dependence. Besides its simplicity this aggregation model has a complex behavior that can be observed at the patterns generated. We propose on this work a brief review of some important proprieties of this model and present an algorithm to simulate a DLA aggregates that simpler and efficient compared to others found in the literature.

  12. Constraint Aggregation Principle in Convex Optimization

    OpenAIRE

    Y.M. Ermoliev; Kryazhimskiy, A.V.; Ruszczynski, A.

    1995-01-01

    A general constraint aggregation technique is proposed for convex optimization problems. At each iteration a set of convex inequalities and linear equations is replaced by a single inequality formed as a linear combination of the original constraints. After solving the simplified subproblem, new aggregation coefficients are calculated and the iteration continues. This general aggregation principle is incorporated into a number of specific algorithms. Convergence of the new methods is pro...

  13. Testing aggregation consistency across geography and commodities

    OpenAIRE

    Liu, Qinghua; Shumway, C. Richard

    2004-01-01

    Consistent aggregation of production data across commodities and states was tested using Lewbel's generalized composite commodity theorem (GCCT). This was the first empirical GCCT test for consistent geographic aggregation and was applied to two groups of states. Consistent commodity aggregation was tested in all states for two output groups and three input groups and in one state for a larger number of groups. Using a more powerful test procedure than previously applied to production data, m...

  14. Performance Analysis of Downlink Inter-band Carrier Aggregation in LTE-Advanced

    DEFF Research Database (Denmark)

    Wang, Hua; Rosa, Claudio; Pedersen, Klaus

    2011-01-01

    Carrier aggregation (CA) is one of the most distinct features for LTE-Advanced systems, which can support a much wider transmission bandwidth up to 100 MHz by aggregating two or more individual component carriers (CCs) belonging to the same (intra-band) or different (inter-band) frequency bands. ...... CC can be different. In this paper, we investigate the downlink resource allocation for inter-band CA, i.e., how to assign carrier(s) to different UEs. A simple yet effective G-factor based carrier selection algorithm, which takes both traffic load and radio channel characteristics...

  15. Gramicidin Channels: Versatile Tools

    Science.gov (United States)

    Andersen, Olaf S.; Koeppe, Roger E., II; Roux, Benoît

    Gramicidin channels are miniproteins in which two tryptophan-rich subunits associate by means of transbilayer dimerization to form the conducting channels. That is, in contrast to other ion channels, gramicidin channels do not open and close; they appear and disappear. Each subunit in the bilayer-spanning channel is tied to the bilayer/solution interface through hydrogen bonds that involve the indole NH groups as donors andwater or the phospholipid backbone as acceptors. The channel's permeability characteristics are well-defined: gramicidin channels are selective for monovalent cations, with no measurable permeability to anions or polyvalent cations; ions and water move through a pore whose wall is formed by the peptide backbone; and the single-channel conductance and cation selectivity vary when the amino acid sequence is varied, even though the permeating ions make no contact with the amino acid side chains. Given the plethora of available experimental information—for not only the wild-type channels but also for channels formed by amino acid-substituted gramicidin analogues—gramicidin channels continue to provide important insights into the microphysics of ion permeation through bilayer-spanning channels. For similar reasons, gramicidin channels constitute a system of choice for evaluating computational strategies for obtaining mechanistic insights into ion permeation through the more complex channels formed by integral membrane proteins.

  16. Joint estimation of preferential attachment and node fitness in growing complex networks.

    Science.gov (United States)

    Pham, Thong; Sheridan, Paul; Shimodaira, Hidetoshi

    2016-09-07

    Complex network growth across diverse fields of science is hypothesized to be driven in the main by a combination of preferential attachment and node fitness processes. For measuring the respective influences of these processes, previous approaches make strong and untested assumptions on the functional forms of either the preferential attachment function or fitness function or both. We introduce a Bayesian statistical method called PAFit to estimate preferential attachment and node fitness without imposing such functional constraints that works by maximizing a log-likelihood function with suitably added regularization terms. We use PAFit to investigate the interplay between preferential attachment and node fitness processes in a Facebook wall-post network. While we uncover evidence for both preferential attachment and node fitness, thus validating the hypothesis that these processes together drive complex network evolution, we also find that node fitness plays the bigger role in determining the degree of a node. This is the first validation of its kind on real-world network data. But surprisingly the rate of preferential attachment is found to deviate from the conventional log-linear form when node fitness is taken into account. The proposed method is implemented in the R package PAFit.

  17. Joint estimation of preferential attachment and node fitness in growing complex networks.

    Science.gov (United States)

    Pham, Thong; Sheridan, Paul; Shimodaira, Hidetoshi

    2016-01-01

    Complex network growth across diverse fields of science is hypothesized to be driven in the main by a combination of preferential attachment and node fitness processes. For measuring the respective influences of these processes, previous approaches make strong and untested assumptions on the functional forms of either the preferential attachment function or fitness function or both. We introduce a Bayesian statistical method called PAFit to estimate preferential attachment and node fitness without imposing such functional constraints that works by maximizing a log-likelihood function with suitably added regularization terms. We use PAFit to investigate the interplay between preferential attachment and node fitness processes in a Facebook wall-post network. While we uncover evidence for both preferential attachment and node fitness, thus validating the hypothesis that these processes together drive complex network evolution, we also find that node fitness plays the bigger role in determining the degree of a node. This is the first validation of its kind on real-world network data. But surprisingly the rate of preferential attachment is found to deviate from the conventional log-linear form when node fitness is taken into account. The proposed method is implemented in the R package PAFit. PMID:27601314

  18. Joint estimation of preferential attachment and node fitness in growing complex networks

    Science.gov (United States)

    Pham, Thong; Sheridan, Paul; Shimodaira, Hidetoshi

    2016-01-01

    Complex network growth across diverse fields of science is hypothesized to be driven in the main by a combination of preferential attachment and node fitness processes. For measuring the respective influences of these processes, previous approaches make strong and untested assumptions on the functional forms of either the preferential attachment function or fitness function or both. We introduce a Bayesian statistical method called PAFit to estimate preferential attachment and node fitness without imposing such functional constraints that works by maximizing a log-likelihood function with suitably added regularization terms. We use PAFit to investigate the interplay between preferential attachment and node fitness processes in a Facebook wall-post network. While we uncover evidence for both preferential attachment and node fitness, thus validating the hypothesis that these processes together drive complex network evolution, we also find that node fitness plays the bigger role in determining the degree of a node. This is the first validation of its kind on real-world network data. But surprisingly the rate of preferential attachment is found to deviate from the conventional log-linear form when node fitness is taken into account. The proposed method is implemented in the R package PAFit. PMID:27601314

  19. [Characteristics of the preferential flow and its response to irrigation amount in oasis cropland].

    Science.gov (United States)

    Yan, Jia-liang; Zhao, Wen-zhil; Zhang, Yong-yong

    2015-05-01

    Preferential flow is a physical process describing how water and solutes move aiong cer- tain pathways through soil profile. Studying the cropland preferential flow patterns and its influential factors could quantify the deep percolation, improve water and fertilizer use efficiency and reduce the risk of agrochemicals contaminating shallow groundwater in oasis cropland. The dye tracer exper- ments were carried out in field oasis cropland, using a brilliant blue FCF solution. The results showed that between ridge and furrow, the number of stained paths densities differed significantly at the 7.3-16.7 cm depth of the soil profiles, while the maximum dye depth had no significant differ- ence. The main influence factors of the maximum stained depth were the irrigation amount and the ant burrows. The maximum stained depth was (43.1 ± 5.9) cm with the mean irrigation amount of 120 mm, however, the maximum stained depth was (68.3 ± 7.6) cm with the irrigation amount of 55 mm under the influence of the ant burrows. Root played an important role in preferential flow, but only the fine roots (Φ ≤ 2 mm) were significantly related to the preferential flow in oasis cropland, while the coarse roots were not. In oasis cropland, the characteristics of the preferential flow were influenced by the irrigation amount, the furrow and ridge planting, the ant burrows and the roots, and the ant burrows were an uncertain factor which affected the maximum infiltration depth of the preferential flow. PMID:26571665

  20. A conceptual model of preferential flow systems in forested hillslopes: evidence of self-organization

    Science.gov (United States)

    Sidle, Roy C.; Noguchi, Shoji; Tsuboyama, Yoshio; Laursen, Karin

    2001-07-01

    Preferential flow paths are known to be important conduits of subsurface stormflow in forest hillslopes. Earlier research on preferential flow paths focused on vertical transport; however, lateral transport is also evident in steep forested slopes underlain by bedrock or till. Macropores consisting of decayed and live roots, subsurface erosion, surface bedrock fractures, and animal burrows form the basis of a backbone for lateral preferential flow in such sites. Evidence from field studies in Japan indicates that although individual macropore segments are generally depressions of the bedrock substrate; fracture flow in weathered bedrock; exchange between macropores and mesopores; and flow at the organic horizon-mineral soil interface and in buried pockets of organic material and loose soil. Here we develop a three-dimensional model for preferential flow systems based on distributed attributes of macropores and potential connecting nodes (e.g. zones of loose soil and buried organic matter). We postulate that the spatially variable and non-linear preferential flow response observed at our Japan field site, as well as at other sites, is attributed to discrete segments of macropores connecting at various nodes within the regolith. Each node is activated by local soil water conditions and is influenced strongly by soil depth, permeability, pore size, organic matter distribution, surface and substrate topography, and possibly momentum dissipation. This study represents the first attempt to characterize the spatially distributed nature of preferential flow paths at the hillslope scale and presents strong evidence that these networks exhibit complex system behaviour.

  1. Spatial patterns in suprabenthic communities in the English Channel

    Science.gov (United States)

    Dauvin, Jean-Claude; Rolet, Céline; Alizier, Sandrine; Ruellet, Thierry

    2011-01-01

    The purpose of this paper was to establish the main characteristics of the suprabenthic communities of the English Channel including those found in a potential aggregate extraction zone located in the central part. Sampling was carried out with a Macer-GIROQ sledge during four periods in 2007. In this offshore site, the suprabenthic faunal composition and abundance were close to those observed in other similar sites in coarse sand to pebbles in the western and eastern parts of the English Channel. But, the species richness was low (65 species). Amphipods were the dominant group in terms of diversity and abundance. Only a few species, mostly amphipods and decapods, showed significant daily migration. Seasonal variations were moderate. Due to the similar suprabenthic fauna having good swimming ability, the aggregate extraction zone in the central part of the Channel could be rapidly colonized after exploitation and thus could rapidly insure a feeding resource for fish, which are attracted by abundant prey.

  2. Channel properties of Nax expressed in neurons.

    Directory of Open Access Journals (Sweden)

    Masahito Matsumoto

    Full Text Available Nax is a sodium-concentration ([Na+]-sensitive Na channel with a gating threshold of ~150 mM for extracellular [Na+] ([Na+]o in vitro. We previously reported that Nax was preferentially expressed in the glial cells of sensory circumventricular organs including the subfornical organ, and was involved in [Na+] sensing for the control of salt-intake behavior. Although Nax was also suggested to be expressed in the neurons of some brain regions including the amygdala and cerebral cortex, the channel properties of Nax have not yet been adequately characterized in neurons. We herein verified that Nax was expressed in neurons in the lateral amygdala of mice using an antibody that was newly generated against mouse Nax. To investigate the channel properties of Nax expressed in neurons, we established an inducible cell line of Nax using the mouse neuroblastoma cell line, Neuro-2a, which is endogenously devoid of the expression of Nax. Functional analyses of this cell line revealed that the [Na+]-sensitivity of Nax in neuronal cells was similar to that expressed in glial cells. The cation selectivity sequence of the Nax channel in cations was revealed to be Na+ ≈ Li+ > Rb+ > Cs+ for the first time. Furthermore, we demonstrated that Nax bound to postsynaptic density protein 95 (PSD95 through its PSD95/Disc-large/ZO-1 (PDZ-binding motif at the C-terminus in neurons. The interaction between Nax and PSD95 may be involved in promoting the surface expression of Nax channels because the depletion of endogenous PSD95 resulted in a decrease in Nax at the plasma membrane. These results indicated, for the first time, that Nax functions as a [Na+]-sensitive Na channel in neurons as well as in glial cells.

  3. Pre-aggregation for Probability Distributions

    DEFF Research Database (Denmark)

    Timko, Igor; Dyreson, Curtis E.; Pedersen, Torben Bach

    Motivated by the increasing need to analyze complex uncertain multidimensional data (e.g., in order to optimize and personalize location-based services), this paper proposes novel types of {\\em probabilistic} OLAP queries that operate on aggregate values that are probability distributions...... and the techniques to process these queries. The paper also presents the methods for computing the probability distributions, which enables pre-aggregation, and for using the pre-aggregated distributions for further aggregation. In order to achieve good time and space efficiency, the methods perform approximate...... multidimensional data analysis that is considered in this paper (i.e., approximate processing of probabilistic OLAP queries over probability distributions)....

  4. Aggregated Dynamic Dataflow Graph Generation and Visualization

    Directory of Open Access Journals (Sweden)

    I. Szabó

    2013-12-01

    Full Text Available Aggregated Dynamic Dataflow Graphs can assist programmers to uncover the main data paths of a given algorithm. This information can be useful when scaling a singlethreaded program into a multi-core architecture. The amount of data movements is crucial when targeting for cache incoherent and/or heterogeneous platforms. This paper presents two methods for generating function-level Aggregated Dynamic Dataflow Graphs. Instruction level trace log was used as a basis, which was generated by Microsoft Giano processor simulator platform. Top-down aggregation strategy and relational database was used to speed up the generation of different views of the aggregated dataflow and call graphs.

  5. Microbial aggregates in anaerobic wastewater treatment.

    Science.gov (United States)

    Kosaric, N; Blaszczyk, R

    1990-01-01

    The phenomenon aggregation of anaerobic bacteria gives an opportunity to speed up the digestion rate during methanogenesis. The aggregates are mainly composed of methanogenic bacteria which convert acetate and H2/CO2 into methane. Other bacteria are also included in the aggregates but their concentration is rather small. The aggregates may also be formed during acetogenesis or even hydrolysis but such aggregates are not stable and disrupt quickly when not fed. A two stage process seems to be suitable when high concentrated solid waste must be treated. Special conditions are necessary to promote aggregate formation from methanogenic bacteria but aggregates once formed are stable without feeding even for a few years. The structure, texture and activity of bacterial aggregates depend on several parameters: (1)--temperature and pH, (2)--wastewater composition and (3)--hydrodynamic conditions within the reactor. The common influence of all these parameters is still rather unknown but some recommendations may be given. Temperature and pH should be maintained in the range which is optimal for methanogenic bacteria e.g. a temperature between 32 and 50 degrees C and a value pH between 6.5 and 7.5. Wastewaters should contain soluble wastes and the specific loading rate should be around one kgCOD(kgVSS)-1 d-1. The concentration of the elements influences aggregate composition and probably structure and texture. At high calcium concentration a change in the colour of the granules has been observed. Research is necessary to investigate the influence of other elements and organic toxicants on maintenance of the aggregates. Hydrodynamic conditions seem to influence the stability of the granules over long time periods. At low liquid stream rates, aggregates may starve and lysis within the aggregates is possible which results in hollowing of aggregates and their floating. At high liquid stream rates the aggregates may be disrupted and washed out of the reactor as a flocculent

  6. Collisional Aggregation due to Turbulence

    CERN Document Server

    Pumir, Alain

    2015-01-01

    Collisions between particles suspended in a fluid play an important role in many physical processes. As an example, collisions of microscopic water droplets in clouds are a necessary step in the production of macroscopic raindrops. Collisions of dust grains are also conjectured to be important for planet formation in the gas surrounding young stars, and also to play a role in the dynamics of sand storms. In these processes, collisions are favoured by fast turbulent motions. Here we review recent advances in the understanding of collisional aggregation due to turbulence. We discuss the role of fractal clustering of particles, and caustic singularities of their velocities. We also discuss limitations of the Smoluchowski equation for modelling these processes. These advances lead to a semi-quantitative understanding on the influence of turbulence on collision rates, and point to deficiencies in the current understanding of rainfall and planet formation.

  7. Multi-Channel Retailing

    Directory of Open Access Journals (Sweden)

    Dirk Morschett, Dr.,

    2005-01-01

    Full Text Available Multi-channel retailing entails the parallel use by retailing enterprises of several sales channels. The results of an online buyer survey which has been conducted to investigate the impact of multi-channel retailing (i.e. the use of several retail channels by one retail company on consumer behaviour show that the frequently expressed concern that the application of multi-channel systems in retailing would be associated with cannibalization effects, has proven unfounded. Indeed, the appropriate degree of similarity, consistency, integration and agreement achieves the exact opposite. Different channels create different advantages for consumers. Therefore the total benefit an enterprise which has a multi-channel system can offer to its consumers is larger, the greater the number of available channels. The use of multi-channel systems is associated with additional purchases in the different channels. Such systems are thus superior to those offering only one sales channel to their customers. Furthermore, multi-channel systems with integrated channels are superior to those in which the channels are essentially autonomous and independent of one another. In integrated systems, consumers can achieve synergy effects in the use of sales-channel systems. Accordingly, when appropriately formulated, multi-channel systems in retailing impact positively on consumers. They use the channels more frequently, buy more from them and there is a positive customer-loyalty impact. Multi-channel systems are strategic options for achieving customer loyalty, exploiting customer potential and for winning new customers. They are thus well suited for approaching differing and varied target groups.

  8. Aggregate size distribution of the soil loss

    Science.gov (United States)

    Szabó, Judit Alexandra; Jakab, Gergely; Szabó, Boglárka; Józsa, Sándor; Szalai, Zoltán; Centeri, Csaba

    2016-04-01

    In agricultural areas the soil erosion and soil loss estimation is vital information in long-term planning. During the initial period of the erosion a part of the soil particles and aggregates get transportable and nutrients and organic matter could be transported due to the effect of water or wind. This preliminary phase was studied with laboratory-scale rainfall simulator. Developed surface crust and aggregate size composition of the runoff was examined in six different slope-roughness-moisture content combination of a Cambisol and a Regosol. The ratio of micro- and macro aggregates in the runoff indicate the stability of the aggregates and determine the transport capacity of the runoff. Both soil samples were taken from field where the water erosion is a potential hazard. During the experiment the whole amount of runoff and sediment was collected through sieve series to a bucket to separate the micro- and macro aggregates. In case of both samples the micro aggregates dominate in the runoff and the runoff rates are similar. Although the runoff of the Regosol - with dominant >1000μm macro aggregate content - contained almost nothing but ratio 250-1000μm sized macro aggregates. This difference occurred because the samples are resistant against drop erosion differently. In case of both sample the selectivity of the erosion and substance matrix redistribution manifested in mineral crusts in the surface where the quartz deposited in place while the lighter organic matter transported with the sediment. The detachment of the aggregates and the redistribution of the particles highly effect on the aggregate composition of the runoff which is connected with the quality of the soil loss. So while the estimation of soil loss quantity is more or less is easy, measuring aggregate size distribution which is led to nutrient and organic matter redistribution is one of a key questions to improve erosion estimation. G. Jakab was supported by the János Bolyai fellowship of the

  9. Preformed Seeds Modulate Native Insulin Aggregation Kinetics.

    Science.gov (United States)

    Dutta, Colina; Yang, Mu; Long, Fei; Shahbazian-Yassar, Reza; Tiwari, Ashutosh

    2015-12-10

    Insulin aggregates under storage conditions via disulfide interchange reaction. It is also known to form aggregates at the site of repeated injections in diabetes patients, leading to injection amyloidosis. This has fueled research in pharmaceutical and biotechnology industry as well as in academia to understand factors that modulate insulin stability and aggregation. The main aim of this study is to understand the factors that modulate aggregation propensity of insulin under conditions close to physiological and measure effect of "seeds" on aggregation kinetics. We explored the aggregation kinetics of insulin at pH 7.2 and 37 °C in the presence of disulfide-reducing agent dithiothreitol (DTT), using spectroscopy (UV-visible, fluorescence, and Fourier transform infrared spectroscopy) and microscopy (scanning electron microscopy, atomic force microscopy) techniques. We prepared insulin "seeds" by incubating disulfide-reduced insulin at pH 7.2 and 37 °C for varying lengths of time (10 min to 12 h). These seeds were added to the native protein and nucleation-dependent aggregation kinetics was measured. Aggregation kinetics was fastest in the presence of 10 min seeds suggesting they were nascent. Interestingly, intermediate seeds (30 min to 4 h incubation) resulted in formation of transient fibrils in 4 h that converted to amorphous aggregates upon longer incubation of 24 h. Overall, the results show that insulin under disulfide reducing conditions at pH and temperature close to physiological favors amorphous aggregate formation and seed "maturity" plays an important role in nucleation dependent aggregation kinetics.

  10. Aggregate composition and stability of structural aggregates of non-calcareous rendzinas in Eastern Serbia

    OpenAIRE

    Gajić Boško; Živković Miodrag

    2006-01-01

    The present study includes the results of comparative investigations of aggregate composition and water stability of structural aggregates in humus horizons of non-calcareous rendzina under native forest and pasture vegetations and the same rendzina utilized long-term as arable field. The results show that aggregate composition and water stability of structural aggregates in the cultivated non-calcareous rendzina are significantly impaired due to a long-term anthropogenization. In the cultiva...

  11. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    OpenAIRE

    Hisham Qasrawi; Iqbal Marie

    2013-01-01

    The effect of using recycled concrete aggregates (RCA) on the basic properties of normal concrete is studied. First, recycled aggregate properties have been determined and compared to those of normal aggregates. Except for absorption, there was not a significant difference between the two. Later, recycled aggregates were introduced in concrete mixes. In these mixes, natural coarse aggregate was partly or totally replaced by recycled aggregates. Results show that the use of recycled aggregates...

  12. Impact of Particle Aggregation on Nanoparticle Reactivity

    Science.gov (United States)

    Jassby, David

    2011-12-01

    The prevalence of nanoparticles in the environment is expected to grow in the coming years due to their increasing pervasiveness in consumer and industrial applications. Once released into the environment, nanoparticles encounter conditions of pH, salinity, UV light, and other solution conditions that may alter their surface characteristics and lead to aggregation. The unique properties that make nanoparticles desirable are a direct consequence of their size and increased surface area. Therefore, it is critical to recognize how aggregation alters the reactive properties of nanomaterials, if we wish to understand how these properties are going to behave once released into the environment. The size and structure of nanoparticle aggregates depend on surrounding conditions, including hydrodynamic ones. Depending on these conditions, aggregates can be large or small, tightly packed or loosely bound. Characterizing and measuring these changes to aggregate morphology is important to understanding the impact of aggregation on nanoparticle reactive properties. Examples of decreased reactivity due to aggregation include the case where tightly packed aggregates have fewer available surface sites compared to loosely packed ones; also, photocatalytic particles embedded in the center of large aggregates will experience less light when compared to particles embedded in small aggregates. However, aggregation also results in an increase in solid-solid interfaces between nanoparticles. This can result in increased energy transfer between neighboring particles, surface passivation, and altered surface tension. These phenomena can lead to an increase in reactivity. The goal of this thesis is to examine the impacts of aggregation on the reactivity of a select group of nanomaterials. Additionally, we examined how aggregation impacts the removal efficiency of fullerene nanoparticles using membrane filtration. The materials we selected to study include ZnS---a metal chalcogenide

  13. RELATIONSHIPS BETWEEN SOIL MICROBIAL BIOMASS, AGGREGATE STABILITY AND AGGREGATE ASSOCIATED-C: A MECHANISTIC APPROACH

    Directory of Open Access Journals (Sweden)

    Patrizia Guidi

    2014-01-01

    Full Text Available For the identification of C pools involved in soil aggregation, a physically-based aggregate fractionation was proposed, and  additional pretreatments were used in the measurement of the 1-2 mm aggregate stability in order to elucidate the relevance of the role of soil microorganisms with respect to the different aggregate breakdown mechanisms. The study was carried out on three clay loam Regosols, developed on calcareous shales, known history of organic cultivation.Our results showed that the soil C pool controlling the process of stabilisation of aggregates was related to the microbial community. We identified the resistance to fast wetting as the major mechanism of aggregate stability driven by microorganims. The plausible hypothesis is that organic farming promotes fungi growth, improving water repellency of soil aggregates by fungal hydrophobic substances. By contrast, we failed in the identification of C pools controlling the formation of aggregates, probably because of the disturbance of mechanical tillage which contributes to the breakdown of soil aggregates.The physically-based aggregate fractionation proposed in this study resulted useful in the  mechanistically understanding of the role of microorganisms in soil aggregation and it might be suggested for studying the impact of management on C pools, aggregates properties and their relationships in agricultural soils.

  14. Calcium channel blocker overdose

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002580.htm Calcium channel blocker overdose To use the sharing features on this page, please enable JavaScript. Calcium channel blockers are a type of medicine used ...

  15. Dynamic channel allocation

    OpenAIRE

    Kaminsky, Andrew D.

    2003-01-01

    Approved for public release; distribution in unlimited. Dynamic Channel Allocation (DCA) offers the possibility of capturing unused channel capacity by allocating unused resources between competing network nodes. This can reduce or possibly eliminate channels sitting idle while information awaits transmission. This holds potential for increasing throughput on bandwidth constrained networks. The purpose of this thesis is to examine the techniques used to allocate channels on demand and acc...

  16. Morphology and mobility of synthetic colloidal aggregates.

    Science.gov (United States)

    Melas, Anastasios D; Isella, Lorenzo; Konstandopoulos, Athanasios G; Drossinos, Yannis

    2014-03-01

    The relationship between geometric and dynamic properties of fractal-like aggregates is studied in the continuum mass and momentum-transfer regimes. The synthetic aggregates were generated by a cluster-cluster aggregation algorithm. The analysis of their morphological features suggests that the fractal dimension is a descriptor of a cluster's large-scale structure, whereas the fractal prefactor is a local-structure indicator. For a constant fractal dimension, the prefactor becomes also an indicator of a cluster's shape anisotropy. The hydrodynamic radius of orientationally averaged aggregates was calculated via molecule-aggregate collision rates determined from the solution of a Laplace equation. An empirical expression that relates the aggregate hydrodynamic radius to its radius of gyration and the number of primary particles is proposed. The suggested expression depends only on geometrical quantities, being independent of statistical (ensemble-averaged) properties like the fractal dimension and prefactor. Hydrodynamic radius predictions for a variety of fractal-like aggregates are in very good agreement with predictions of other methods and literature values. Aggregate dynamic shape factors and DLCA individual monomer hydrodynamic shielding factors are also calculated. PMID:24407656

  17. Protein aggregation in amyotrophic lateral sclerosis

    NARCIS (Netherlands)

    Blokhuis, Anna M.; Groen, Ewout J. N.; Koppers, Max; van den Berg, Leonard H.; Pasterkamp, R. Jeroen

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the aggregation of ubiquitinated proteins in affected motor neurons. Recent studies have identified several new molecular constituents of ALS-linked cellular aggregates, including FUS, TDP-43, OPTN, UBQLN2 and the tr

  18. Familial Aggregation and Childhood Blood Pressure

    NARCIS (Netherlands)

    Wang, Xiaoling; Xu, Xiaojing; Su, Shaoyong; Snieder, Harold

    2015-01-01

    There is growing concern about elevated blood pressure (BP) in children. The evidence for familial aggregation of childhood BP is substantial. Twin studies have shown that a large part of the familial aggregation of childhood BP is due to genes. The first part of this review provides the latest prog

  19. Streaming instability of aggregating slime mold amoebae

    Science.gov (United States)

    Levine, Herbert; Reynolds, William

    1991-05-01

    We propose a new model of aggregation in the cellular slime mold D. Discoideum. Our approach couples the excitable signaling system to amoeba chemotaxis; the resultant system of equations is tractable to analytical and numerical approaches. Using our model, we derive the existence of a streaming instability for the concentric target aggregation pattern.

  20. Teaching Aggregate Demand and Supply Models

    Science.gov (United States)

    Wells, Graeme

    2010-01-01

    The author analyzes the inflation-targeting model that underlies recent textbook expositions of the aggregate demand-aggregate supply approach used in introductory courses in macroeconomics. He shows how numerical simulations of a model with inflation inertia can be used as a tool to help students understand adjustments in response to demand and…

  1. Ratio-Based Gradual Aggregation of Data

    DEFF Research Database (Denmark)

    Iftikhar, Nadeem

    2012-01-01

    cause data management and data storage issues. However, non-flexible and ineffective means of data aggregation not only reduce performance of database queries but also lead to erroneous reporting. This paper presents flexible and effective ratio-based methods for gradual data aggregation in databases...

  2. Teaching Aggregate Demand and Supply Models

    OpenAIRE

    Wells, Graeme

    2007-01-01

    This note analyses the inflation-targeting model that underlies recent textbook expositions of the Aggregate Demand-Aggregate Supply approach used in introductory courses in macroeconomics. The paper shows how numerical simulations of a model with inflation inertia can be used as a tool to help students understand adjustments in response to demand and supply shocks of various kinds.

  3. Oxidation, aggregation and immunogenicity of therapeutic proteins

    NARCIS (Netherlands)

    Torosantucci, Riccardo

    2013-01-01

    The aim of the research described in this thesis is to study the chemical mechanisms responsible for protein aggregation induced by metal catalyzed oxidation and to investigate the relationship between protein oxidation, aggregation and immunogenicity. To this end, recombinant human insulin rhIFNβ-1

  4. Effects of preferential flow on soil-water and surface runoff in a forested watershed in China

    Institute of Scientific and Technical Information of China (English)

    Jinhua CHENG; Hongjiang ZHANG; Youyan ZHANG; Yuhu SHI; Yun CHENG

    2009-01-01

    Preferential flow is a runoff mechanism intermediate between matrix flow and surface flow, transmitting water at high velocity through the subsurface zone. To assess the effect of preferential flow on soil-water flow and surface runoff in a forested watershed, precipitation and volumes of preferential flow, matrix flow and surface runoff were measured over a period of four years in a forested watershed in the Three Gorges area of southern China. Results show that preferential-flow hydrographs have gentler rises and steeper recessions than those for matrix flow and surface runoff. Preferential flow as a percentage of soil-water flow ranged from 2.40% to 8.72% and the maximum preferential-flow velocity exceeded as much as 5600 times that of matrix flow. This shows that preferential flow plays an important role in the movement of soil water. Preferential flow has a significant effect on peak surface runoff by increasing the surface runoff rate and accelerating the appearance of peak surface runoff. Preferential flow can also prolong the duration of surface runoff. Surface runoff was observed to be positively correlated with preferential flow. The greater the sum of rainfall amount and antecedent precipitation is, the greater the effect of preferential flow on surface runoff is.

  5. Desynched channels on IRCnet

    CERN Document Server

    Hansen, Michael

    2008-01-01

    In this paper we describe what a desynchronised channel on IRC is. We give procedures on how to create such a channel and how to remove desynchronisation. We explain which types of desynchronisation there are, what properties desynchronised channels have, and which properties can be exploited.

  6. Quantum Binary Symmetric Channels

    Institute of Scientific and Technical Information of China (English)

    陈小余; 仇佩亮

    2001-01-01

    Quantum binary symmetric channels are defined via the invariance of fidelity under unitary transformations ofthe input density operators. In this definition, they not only include the most studied case of the depolarizingchannel but also other channels. We investigate the character of the latter and find the maximum of the coherentinformation to estimate the capacities of the channels.

  7. Quantum Multiple Access Channel

    Institute of Scientific and Technical Information of China (English)

    侯广; 黄民信; 张永德

    2002-01-01

    We consider the transmission of classical information over a quantum channel by many senders, which is a generalization of the two-sender case. The channel capacity region is shown to be a convex hull bound by the yon Neumann entropy and the conditional yon Neumann entropies. The result allows a reasonable distribution of channel capacity over the senders.

  8. Cardiac potassium channel subtypes

    DEFF Research Database (Denmark)

    Schmitt, Nicole; Grunnet, Morten; Olesen, Søren-Peter

    2014-01-01

    About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K(+) channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K(+) channels...

  9. KV7 potassium channels

    DEFF Research Database (Denmark)

    Stott, Jennifer B; Jepps, Thomas Andrew; Greenwood, Iain A

    2014-01-01

    Potassium channels are key regulators of smooth muscle tone, with increases in activity resulting in hyperpolarisation of the cell membrane, which acts to oppose vasoconstriction. Several potassium channels exist within smooth muscle, but the KV7 family of voltage-gated potassium channels have been...

  10. Aggregation of Composite Solutions: strategies, models, examples

    CERN Document Server

    Levin, Mark Sh

    2011-01-01

    The paper addresses aggregation issues for composite (modular) solutions. A systemic view point is suggested for various aggregation problems. Several solution structures are considered: sets, set morphologies, trees, etc. Mainly, the aggregation approach is targeted to set morphologies. The aggregation problems are based on basic structures as substructure, superstructure, median/consensus, and extended median/consensus. In the last case, preliminary structure is built (e.g., substructure, median/consensus) and addition of solution elements is considered while taking into account profit of the additional elements and total resource constraint. Four aggregation strategies are examined: (i) extension strategy (designing a substructure of initial solutions as "system kernel" and extension of the substructure by additional elements); (ii) compression strategy (designing a superstructure of initial solutions and deletion of some its elements); (iii) combined strategy; and (iv) new design strategy to build a new s...

  11. Competitive aggregation dynamics using phase wave signals.

    Science.gov (United States)

    Sakaguchi, Hidetsugu; Maeyama, Satomi

    2014-10-21

    Coupled equations of the phase equation and the equation of cell concentration n are proposed for competitive aggregation dynamics of slime mold in two dimensions. Phase waves are used as tactic signals of aggregation in this model. Several aggregation clusters are formed initially, and target patterns appear around the localized aggregation clusters. Owing to the competition among target patterns, the number of the localized aggregation clusters decreases, and finally one dominant localized pattern survives. If the phase equation is replaced with the complex Ginzburg-Landau equation, several spiral patterns appear, and n is localized near the center of the spiral patterns. After the competition among spiral patterns, one dominant spiral survives. PMID:24956327

  12. Dynamic Approaches to In-Network Aggregation

    CERN Document Server

    Kennedy, Oliver; Demers, Al

    2008-01-01

    Collaboration between small-scale wireless devices hinges on their ability to infer properties shared across multiple nearby nodes. Wireless-enabled mobile devices in particular create a highly dynamic environment not conducive to distributed reasoning about such global properties. This paper addresses a specific instance of this problem: distributed aggregation. We present extensions to existing unstructured aggregation protocols that enable estimation of count, sum, and average aggregates in highly dynamic environments. With the modified protocols, devices with only limited connectivity can maintain estimates of the aggregate, despite \\textit{unexpected} peer departures and arrivals. Our analysis of these aggregate maintenance extensions demonstrates their effectiveness in unstructured environments despite high levels of node mobility.

  13. Ratio-Based Gradual Aggregation of Data

    DEFF Research Database (Denmark)

    Iftikhar, Nadeem

    2012-01-01

    cause data management and data storage issues. However, non-flexible and ineffective means of data aggregation not only reduce performance of database queries but also lead to erroneous reporting. This paper presents flexible and effective ratio-based methods for gradual data aggregation in databases....... Gradual data aggregation is a process that reduces data volume by converting the detailed data into multiple levels of summarized data as the data gets older. This paper also describes implementation strategies of the proposed methods based on standard database technology.......Majority of databases contain large amounts of data, gathered over long intervals of time. In most cases, the data is aggregated so that it can be used for analysis and reporting purposes. The other reason of data aggregation is to reduce data volume in order to avoid over-sized databases that may...

  14. Compressive Strength of Concrete Using Recycled Concrete Aggregate as Complete Replacement of Natural Aggregate

    OpenAIRE

    Osei, Daniel Yaw

    2013-01-01

    This paper presents a report of an experimental investigation on the effect of complete replacement of natural aggregate by recycled concrete aggregate in the production of concrete on the compressive strength of concrete. Two sets of concrete mixtures of ratios 1:3:6, 1:2:4, 1:11/2:3, 1:1:2 by mass were cast using natural aggregates and recycled aggregates concrete respectively. The 28-day compressive strengths of 1:3:6, 1:2:4, 1:11/2:3, 1:1:2 concrete using recycled concrete aggregates were...

  15. A novel potassium channel in skeletal muscle mitochondria.

    Science.gov (United States)

    Skalska, Jolanta; Piwońska, Marta; Wyroba, Elzbieta; Surmacz, Liliana; Wieczorek, Rafal; Koszela-Piotrowska, Izabela; Zielińska, Joanna; Bednarczyk, Piotr; Dołowy, Krzysztof; Wilczynski, Grzegorz M; Szewczyk, Adam; Kunz, Wolfram S

    2008-01-01

    In this work we provide evidence for the potential presence of a potassium channel in skeletal muscle mitochondria. In isolated rat skeletal muscle mitochondria, Ca(2+) was able to depolarize the mitochondrial inner membrane and stimulate respiration in a strictly potassium-dependent manner. These potassium-specific effects of Ca(2+) were completely abolished by 200 nM charybdotoxin or 50 nM iberiotoxin, which are well-known inhibitors of large conductance, calcium-activated potassium channels (BK(Ca) channel). Furthermore, NS1619, a BK(Ca)-channel opener, mimicked the potassium-specific effects of calcium on respiration and mitochondrial membrane potential. In agreement with these functional data, light and electron microscopy, planar lipid bilayer reconstruction and immunological studies identified the BK(Ca) channel to be preferentially located in the inner mitochondrial membrane of rat skeletal muscle fibers. We propose that activation of mitochondrial K(+) transport by opening of the BK(Ca) channel may be important for myoprotection since the channel opener NS1619 protected the myoblast cell line C2C12 against oxidative injury.

  16. Anisotropic diffusion-limited aggregation.

    Science.gov (United States)

    Popescu, M N; Hentschel, H G E; Family, F

    2004-06-01

    Using stochastic conformal mappings, we study the effects of anisotropic perturbations on diffusion-limited aggregation (DLA) in two dimensions. The harmonic measure of the growth probability for DLA can be conformally mapped onto a constant measure on a unit circle. Here we map m preferred directions for growth to a distribution on the unit circle, which is a periodic function with m peaks in [-pi,pi) such that the angular width sigma of the peak defines the "strength" of anisotropy kappa= sigma(-1) along any of the m chosen directions. The two parameters (m,kappa) map out a parameter space of perturbations that allows a continuous transition from DLA (for small enough kappa ) to m needlelike fingers as kappa--> infinity. We show that at fixed m the effective fractal dimension of the clusters D(m,kappa) obtained from mass-radius scaling decreases with increasing kappa from D(DLA) approximately 1.71 to a value bounded from below by D(min) = 3 / 2. Scaling arguments suggest a specific form for the dependence of the fractal dimension D(m,kappa) on kappa for large kappa which compares favorably with numerical results. PMID:15244564

  17. The fractal aggregation of asphaltenes.

    Science.gov (United States)

    Hoepfner, Michael P; Fávero, Cláudio Vilas Bôas; Haji-Akbari, Nasim; Fogler, H Scott

    2013-07-16

    This paper discusses time-resolved small-angle neutron scattering results that were used to investigate asphaltene structure and stability with and without a precipitant added in both crude oil and model oil. A novel approach was used to isolate the scattering from asphaltenes that are insoluble and in the process of aggregating from those that are soluble. It was found that both soluble and insoluble asphaltenes form fractal clusters in crude oil and the fractal dimension of the insoluble asphaltene clusters is higher than that of the soluble clusters. Adding heptane also increases the size of soluble asphaltene clusters without modifying the fractal dimension. Understanding the process of insoluble asphaltenes forming fractals with higher fractal dimensions will potentially reveal the microscopic asphaltene destabilization mechanism (i.e., how a precipitant modifies asphaltene-asphaltene interactions). It was concluded that because of the polydisperse nature of asphaltenes, no well-defined asphaltene phase stability envelope exists and small amounts of asphaltenes precipitated even at dilute precipitant concentrations. Asphaltenes that are stable in a crude oil-precipitant mixture are dispersed on the nanometer length scale. An asphaltene precipitation mechanism is proposed that is consistent with the experimental findings. Additionally, it was found that the heptane-insoluble asphaltene fraction is the dominant source of small-angle scattering in crude oil and the previously unobtainable asphaltene solubility at low heptane concentrations was measured. PMID:23808932

  18. Familial aggregation of bladder cancer

    Directory of Open Access Journals (Sweden)

    Ilić Milena

    2011-01-01

    Full Text Available Background. Except for smoking and certain occupational exposures, the etiology of bladder cancer is largely unknown. Several case reports have described familial aggregation of transitional cell carcinoma of the bladder. Although the majority of patients with bladder cancer do not have family history of transitional cell carcinoma of the urinary tract, the study of familial transitional cell carcinoma may lead to the knowledge on the pathogenesis of this disease. The purpose of this study was to describe three cases of urinary bladder cancer in a single three-member family, i.e. in two generations (mother and son and a family member related by marriage (the patient’s wife. Case report. Three cases of urinary bladder cancer occurred in a three-member family within the interval of 5 years. The following common characteristics were detected in our patients: old age (over 60, working as farmers for more than 50 years, negative personal medical history on relevant health disorders, place of birth - village, place of residence - village, the same water supply, similar nutrition, positive family history on urinary bladder cancer or other malignant tumors, the first sign of illness was macroscopic hematuria in all the patients and the same pathohistological type of cancer - carcinoma papillare transitiocellulare. Conclusion. The stated common characteristics in our cases indicate, above all, the impact of exposure to external surrounding factors on the occurrence of urinary bladder cancer.

  19. Modeling preferential water flow and solute transport in unsaturated soil using the active region model

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, F.; Wang, K.; Zhang, R.; Liu, H.H.

    2009-03-15

    Preferential flow and solute transport are common processes in the unsaturated soil, in which distributions of soil water content and solute concentrations are often characterized as fractal patterns. An active region model (ARM) was recently proposed to describe the preferential flow and transport patterns. In this study, ARM governing equations were derived to model the preferential soil water flow and solute transport processes. To evaluate the ARM equations, dye infiltration experiments were conducted, in which distributions of soil water content and Cl{sup -} concentration were measured. Predicted results using the ARM and the mobile-immobile region model (MIM) were compared with the measured distributions of soil water content and Cl{sup -} concentration. Although both the ARM and the MIM are two-region models, they are fundamental different in terms of treatments of the flow region. The models were evaluated based on the modeling efficiency (ME). The MIM provided relatively poor prediction results of the preferential flow and transport with negative ME values or positive ME values less than 0.4. On the contrary, predicted distributions of soil water content and Cl- concentration using the ARM agreed reasonably well with the experimental data with ME values higher than 0.8. The results indicated that the ARM successfully captured the macroscopic behavior of preferential flow and solute transport in the unsaturated soil.

  20. [Surrounding characteristics of preferential flow in cultivated typical black soils of northeast China].

    Science.gov (United States)

    Jiang, Xiao-jin; Wang, En-heng; Chen, Xiang-wei; Xia, Xiang-you; Shi, Chang-ting

    2010-12-01

    Taking the cultivated soils in typical black soil region of Northeast China as test objects, and by using dye tracer and double-ring infiltrometer techniques and photograph interpretation method, this paper measured and analyzed the dye-stained width and dye-stained coverage of soil transverse and longitudinal sections as well as the field maximum dye-stained depth, aimed to approach the water flow movement pattern and distribution characteristics in test soils. At soil depth 0-15 cm, matrix flow was the main soil water flow movement pattern; at depth 15-20 cm, lateral flow was observed, and the average dye-stained width and dye-stained coverage reached their maximum, being 23 cm and 20.73%, respectively. At depth 20-67 cm, the main soil water flow movement pattern was macro-pore flow, with cracks and macro-pores as the main preferential routes. The cracks at depth 20-35 cm made the preferential flow have distinct surrounding characteristics, and the macro-pores at depth 40-67 cm were the main preferential routes. Due to the existence of the preferential routes of cracks and macro-pores, the migration velocity of water in soil increased by 4.5 times, which could not only cause water loss, but also accelerate the migration of pesticides to ground water. It was suggested that these preferential routes should be decreased or eliminated during the cultivation and management on cultivated typical black soils. PMID:21442999

  1. Preferential flow as a potential mechanism for fire-induced increase in streamflow

    Science.gov (United States)

    Stoof, C. R.; Slingerland, E. C.; Mol, W.; Berg, J.; Vermeulen, P. J.; Ferreira, A. J. D.; Ritsema, C. J.; Parlange, J.-Y.; Steenhuis, T. S.

    2014-02-01

    After vegetation fires, discharge of streams and rivers is often higher than before. This is usually attributed to decreased canopy interception and evapotranspiration caused by vegetation removal, and to increased overland flow resulting from increased soil water repellency. In this paper we examine whether fire-induced changes in preferential flow can reinforce this postfire streamflow response. We studied five recently burned soils and adjacent unburned soils in Portugal and found that by reducing topsoil moisture and increasing soil moisture variability, fire increased the propensity for preferential flow. This was confirmed by 2-D soil moisture and repellency profiles that showed preferential paths in burned soil that were more distinct, wetter, and slightly narrower than in unburned soil. Since water infiltrating along preferential flow paths bypasses the dry soil matrix, we suggest that narrow flow paths promote deep infiltration- which effect size varies with soil depth, (effective) rainfall, and overland flow. We pose that the resulting increase in infiltration increases drainage and interflow because the excess water cannot stay in the soil, and incorporate fire-induced or -enhanced preferential flow into a conceptual model of flow routing that explains the commonly observed increase in stream flow postfire.

  2. On 1-qubit channels

    OpenAIRE

    Uhlmann, Armin

    2000-01-01

    The entropy H_T(rho) of a state rho with respect to a channel T and the Holevo capacity of the channel require the solution of difficult variational problems. For a class of 1-qubit channels, which contains all the extremal ones, the problem can be significantly simplified by associating an Hermitian antilinear operator theta to every channel of the considered class. The concurrence of the channel can be expressed by theta and turns out to be a flat roof. This allows to write down an explicit...

  3. On 1-qubit channels

    CERN Document Server

    Uhlmann, A

    2001-01-01

    The entropy H_T(rho) of a state rho with respect to a channel T and the Holevo capacity of the channel require the solution of difficult variational problems. For a class of 1-qubit channels, which contains all the extremal ones, the problem can be significantly simplified by associating an Hermitian antilinear operator theta to every channel of the considered class. The concurrence of the channel can be expressed by theta and turns out to be a flat roof. This allows to write down an explicit expression for H_T. Its maximum would give the Holevo (1-shot) capacity.

  4. Source and Channel Coding for Correlated Sources Over Multiuser Channels

    OpenAIRE

    Gunduz, Deniz; Erkip, Elza; Goldsmith, Andrea; Poor, H. Vincent

    2008-01-01

    Source and channel coding over multiuser channels in which receivers have access to correlated source side information is considered. For several multiuser channel models necessary and sufficient conditions for optimal separation of the source and channel codes are obtained. In particular, the multiple access channel, the compound multiple access channel, the interference channel and the two-way channel with correlated sources and correlated receiver side information are considered, and the o...

  5. C. elegans TRP channels.

    Science.gov (United States)

    Xiao, Rui; Xu, X Z Shawn

    2011-01-01

    Transient receptor potential (TRP) channels represent a superfamily of cation channels found in all eukaryotes. The C. elegans genome encodes seventeen TRP channels covering all of the seven TRP subfamilies. Genetic analyses in C. elegans have implicated TRP channels in a wide spectrum of behavioral and physiological processes, ranging from sensory transduction (e.g. chemosensation, touch sensation, proprioception and osmosensation) to fertilization, drug dependence, organelle biogenesis, apoptosis, gene expression, and neurotransmitter/hormone release. Many C. elegans TRP channels share similar activation and regulatory mechanisms with their vertebrate counterparts. Studies in C. elegans have also revealed some previously unrecognized functions and regulatory mechanisms of TRP channels. C. elegans represents an excellent genetic model organism for the study of function and regulation of TRP channels in vivo. PMID:21290304

  6. On the Aggregate Interference in Random CSMA/CA Networks: A Stochastic Geometry Approach

    OpenAIRE

    Hwang, June; Choi, Jinho; Jantti, Riku; Kim, Seong-Lyun

    2012-01-01

    In this paper, we investigate the cumulative distribution function (CDF) of the aggregate interference in carrier sensing multiple access/collision avoidance (CSMA/CA) networks measured at an arbitrary time and position. We assume that nodes are deployed in an infinite two-dimensional plane by Poisson point process (PPP) and the channel model follows the singular path loss function and Rayleigh fading. To find the effective active node density we analyze the distributed coordinate function (D...

  7. Spatial Organization of Dual-Species Bacterial Aggregates on Leaf Surfaces

    Science.gov (United States)

    Monier, J.-M.; Lindow, S. E.

    2005-01-01

    The spatial organization of cells within bacterial aggregates on leaf surfaces was determined for pair-wise mixtures of three different bacterial species commonly found on leaves, Pseudomonas syringae, Pantoea agglomerans, and Pseudomonas fluorescens. Cells were coinoculated onto bean plants and allowed to grow under moist conditions, and the resulting aggregates were examined in situ by epifluorescence microscopy. Each bacterial strain could be localized because it expressed either the green or the cyan fluorescent protein constitutively, and the viability of individual cells was assessed by propidium iodide staining. Each pair of bacterial strains that was coinoculated onto leaves formed mixed aggregates. The degree of segregation of cells in mixed aggregates differed between the different coinoculated pairs of strains and was higher in mixtures of P. fluorescens A506 and P. agglomerans 299R and mixtures of P. syringae B728a and P. agglomerans 299R than in mixtures of two isogenic strains of P. agglomerans 299R. The fractions of the total cell population that were dead in mixed and monospecific aggregates of a gfp-marked strain of P. agglomerans 299R and a cfp-marked strain of P. agglomerans 299R, or of P. fluorescens A506 and P. agglomerans 299R, were similar. However, the proportion of dead cells in mixed aggregates of P. syringae B728a and P. agglomerans 299R was significantly higher (13.2% ± 8.2%) than that in monospecific aggregates of these two strains (1.6% ± 0.7%), and it increased over time. While dead cells in such mixed aggregates were preferentially found at the interface between clusters of cells of these strains, cells of these two strains located at the interface did not exhibit equal probabilities of mortality. After 9 days of incubation, about 77% of the P. agglomerans 299R cells located at the interface were dead, while only about 24% of the P. syringae B728a cells were dead. The relevance of our results to understanding bacterial interactions

  8. Flow-induced channelization in a porous medium

    CERN Document Server

    Mahadevan, Amala

    2010-01-01

    We propose a theory for erosional channelization induced by fluid flow in a saturated granular porous medium. When the local fluid flow-induced stress is larger than a critical threshold, grains are dislodged and carried away so that the porosity of the medium is altered by erosion. This in turn affects the local hydraulic conductivity and pressure in the medium and results in the growth and development of channels that preferentially conduct the flow. Our multiphase model involves a dynamical porosity field that evolves along with the volume fraction of the mobile and immobile grains in response to fluid flow that couples the spatiotemporal dynamics of the three phases. Numerical solutions of the resulting initial boundary value problem show how channels form in porous media and highlights how heterogeneity in the erosion threshold dictates the form of the patterns and thus the ability to control them.

  9. Network growth with preferential attachment and without “rich get richer” mechanism

    Science.gov (United States)

    Lachgar, A.; Achahbar, A.

    2016-08-01

    We propose a simple preferential attachment model of growing network using the complementary probability of Barabási-Albert (BA) model, i.e. Π(ki)∝1-ki∑jkj. In this network, new nodes are preferentially attached to not well connected nodes. Numerical simulations, in perfect agreement with the master equation solution, give an exponential degree distribution. This suggests that the power law degree distribution is a consequence of preferential attachment probability together with “rich get richer” phenomena. We also calculate the average degree of a target node at time t() and its fluctuations, to have a better view of the microscopic evolution of the network, and we also compare the results with BA model.

  10. The Experiment and Simulation for Water Movement of Preferential Flow in Soil

    Science.gov (United States)

    Lu, Xiaohui; Li, Qilong

    A large number of lab and field experiments have showed preferential flow is a ubiquitous phenomenon. Through analysis on the field dye experiment, precipitation and infliltration data in the Experimental Station in Zhengzhou and percolation test data in lab and field experiment, the paper analyze the characterization of preferential flow by a method of statistical analysis and discuss the form mechanism together with influencing factor in soil. The results show the field dye experiment of silt loam in Zhumadian, precipitation and infliltration data and the percolation test in the Experimental Station have showed the opore caused by the root and wormhole greatly develops in the upper soil layer, tortuose and decreases with the depth. However, the cranny caused by dry shrinkage comparatively develops in the deep soil layer, the opore has good connectivity, and therefore preferential flow easily occurs in silt loam than sand silt in Kaifeng.

  11. Kinds and meaning of preferential credits for development of agriculture and rural areas

    Directory of Open Access Journals (Sweden)

    Antoni Mickiewicz

    2013-06-01

    Full Text Available The theme of the paper was of preferential credits granted in two periods, that means after Poland’s accession to the European Union (2004-2006 and in the period after introduction of new legal regulations (2007-2010. The institution responsible for realisation of preferential credits was Agency of Restructuring and Modernisation of Agriculture which delegated its rights to banks. The credit policy in first period of our functioning in the European Union relied on gradual ending old legal regulations, not compliant with EU standards and undertaking activities in adaptation of Polish agriculture to standards obeyed in EU-15 Member States. Directions of preferential credits granting were changed in 2007. There were introduced 7 credit lines which aim was improvement of production efficiency, better use of production base in agricultural farms and acceleration of agrarian changes. The biggest beneficiaries of structural pensions were young farmers and farmers who wanted to increase the size of their farms.

  12. Microbial Aggregate and Functional Community Distribution in a Sequencing Batch Reactor with Anammox Granules

    KAUST Repository

    Sun, Shan

    2013-05-01

    Anammox (anaerobic ammonium oxidation) process is a one-step conversion of ammonia into nitrogen gas with nitrite as an electron acceptor. It has been developed as a sustainable technology for ammonia removal from wastewater in the last decade. For wastewater treatment, anammox biomass was widely developed as microbial aggregate where the conditions for enrichment of anammox community must be delicately controlled and growth of other bacteria especially NOB should be suppressed to enhance nitrogen removal efficiency. Little is known about the distribution of microbial aggregates in anammox process. Thus the objective of our study was to assess whether segregation of biomass occurs in granular anammox system. In this study, a laboratory-scale sequential batch reactor (SBR) was successfully operated for a period of 80 days with granular anammox biomass. Temporal and spatial distribution of microbial aggregates was studied by particle characterization system and the distribution of functional microbial communities was studied with qPCR and 16s rRNA amplicon pyrosequencing. Our study revealed the spatial and temporal distribution of biomass aggregates based on their sizes and density. Granules (>200 μm) preferentially accumulated in the bottom of the reactor while floccules (30-200 μm) were relatively rich at the top layer. The average density of aggregate was higher at the bottom than the density of those at the top layer. Degranulation caused by lack of hydrodynamic shear force in the top layer was considered responsible for this phenomenon. NOB was relatively rich in the top layer while percentage of anammox population was higher at the bottom, and anammox bacteria population gradually increased over a period of time. NOB growth was supposed to be associated with the increase of floccules based on the concurrent occurrence. Thus, segregation of biomass can be utilized to develop an effective strategy to enrich anammox and wash out NOB by shortening the settling

  13. Differential effect of HDAC3 on cytoplasmic and nuclear huntingtin aggregates.

    Directory of Open Access Journals (Sweden)

    Tatsuo Mano

    Full Text Available Histone deacetylases (HDACs are potential therapeutic targets of polyglutamine (pQ diseases including Huntington's disease (HD that may function to correct aberrant transcriptional deactivation caused by mutant pQ proteins. HDAC3 is a unique class 1 HDAC found in both the cytoplasm and in the nucleus. However, the precise functions of HDAC3 in the two cellular compartments are only vaguely known. HDAC3 directly binds to huntingtin (Htt with short pQ and this interaction is important for suppressing neurotoxicity induced by HDAC3. With long pQ Htt, the interaction with HDAC3 is inhibited, and this supposedly promotes neuronal death, indicating that HDAC3 would be a good therapeutic target for HD. However, the knockout of one HDAC3 allele did not show any efficacy in reducing neurodegenerative symptoms in a mouse model of HD. Therefore, the role of HDAC3 in the pathogenesis of HD has yet to be fully elucidated. We attempted to resolve this issue by focusing on the different roles of HDAC3 on cytoplasmic and nuclear Htt aggregates. In addition to supporting the previous findings, we found that HDAC3 preferentially binds to nuclear Htt over cytoplasmic ones. Specific HDAC3 inhibitors increased the total amount of Htt aggregates by increasing the amount of nuclear aggregates. Both cytoplasmic and nuclear Htt aggregates were able to suppress endogenous HDAC3 activity, which led to decreased nuclear proteasome activity. Therefore, we concluded that Htt aggregates impair nuclear proteasome activity through the inhibition of HDAC3. Our findings provide new insights regarding cross-compartment proteasome regulation.

  14. Efficient clustering aggregation based on data fragments.

    Science.gov (United States)

    Wu, Ou; Hu, Weiming; Maybank, Stephen J; Zhu, Mingliang; Li, Bing

    2012-06-01

    Clustering aggregation, known as clustering ensembles, has emerged as a powerful technique for combining different clustering results to obtain a single better clustering. Existing clustering aggregation algorithms are applied directly to data points, in what is referred to as the point-based approach. The algorithms are inefficient if the number of data points is large. We define an efficient approach for clustering aggregation based on data fragments. In this fragment-based approach, a data fragment is any subset of the data that is not split by any of the clustering results. To establish the theoretical bases of the proposed approach, we prove that clustering aggregation can be performed directly on data fragments under two widely used goodness measures for clustering aggregation taken from the literature. Three new clustering aggregation algorithms are described. The experimental results obtained using several public data sets show that the new algorithms have lower computational complexity than three well-known existing point-based clustering aggregation algorithms (Agglomerative, Furthest, and LocalSearch); nevertheless, the new algorithms do not sacrifice the accuracy. PMID:22334025

  15. Lightweight alumina refractory aggregate. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Swansiger, T.G.; Pearson, A.

    1996-07-16

    Objective was to develop a lightweight, high alumina refractory aggregate for use in various high performance insulating (low thermal conductivity) refractory applications (e.g., in the aluminium, glass, cement, and iron and steel industries). A new aggregate process was developed through bench and pilot-scale experiments involving extrusion of a blend of calcined and activated alumina powders and organic extrusion aids and binders. The aggregate, with a bulk density approaching 2.5 g/cc, exhibited reduced thermal conductivity and adequate fired strength compared to dense tabular aggregate. Refractory manufacturers were moderately enthusiastic over the results. Alcoa prepared an economic analysis for producing lightweight aggregate, based on a retrofit of this process into existing Alcoa production facilities. However, a new, competing lightweight aggregate material was developed by another company; this material (Plasmal{trademark})had a significantly more favorable cost base than the Alcoa/DOE material, due to cheap raw materials and fewer processing steps. In late 1995, Alcoa became a distributor of Plasmal. Alcoa estimated that {ge}75% of the market originally envisioned for the Alcoa/DOE aggregate would be taken by Plasmal. Hence, it was decided to terminate the contract without the full- scale demonstration.

  16. A nanoscale bio-inspired light-harvesting system developed from self-assembled alkyl-functionalized metallochlorin nano-aggregates

    KAUST Repository

    Ocakoǧlu, Kasim

    2014-01-01

    Self-assembled supramolecular organization of nano-structured biomimetic light-harvesting modules inside solid-state nano-templates can be exploited to develop excellent light-harvesting materials for artificial photosynthetic devices. We present here a hybrid light-harvesting system mimicking the chlorosomal structures of the natural photosynthetic system using synthetic zinc chlorin units (ZnChl-C6, ZnChl-C12 and ZnChl-C 18) that are self-aggregated inside the anodic aluminum oxide (AAO) nano-channel membranes. AAO nano-templates were modified with a TiO2 matrix and functionalized with long hydrophobic chains to facilitate the formation of supramolecular Zn-chlorin aggregates. The transparent Zn-chlorin nano-aggregates inside the alkyl-TiO2 modified AAO nano-channels have a diameter of ∼120 nm in a 60 μm length channel. UV-Vis studies and fluorescence emission spectra further confirm the formation of the supramolecular ZnChl aggregates from monomer molecules inside the alkyl-functionalized nano-channels. Our results prove that the novel and unique method can be used to produce efficient and stable light-harvesting assemblies for effective solar energy capture through transparent and stable nano-channel ceramic materials modified with bio-mimetic molecular self-assembled nano-aggregates. © 2014 the Partner Organisations.

  17. Determination of Preferential Flow Parameters by Means of Inverse Simulation of Tension Disc Experiment

    Science.gov (United States)

    Zumr, D.; Snehota, M.; Nemcova, R.; Cislerova, M.

    2008-12-01

    The field tension and ponded infiltration experiments were conducted to estimate the soil hydraulic properties of the soils with preferential pathways (Distric Cambisol, Sumava). Zones of preferential flow were determined through analyses of photographs taken during laboratory dye tracer infiltration experiments performed on undisturbed soil samples. Connectivity, volumetric ratio and spatial development of preferential pathways were evaluated as the necessary information for numerical simulations of flow using dual-permeability approach. The field infiltration experiment was carried out in a shallow pit for a period of one day. The upper boundary condition was controlled by the tension disk infiltrometer, the propagation of a water front was monitored by two tensiometers installed in two depths below the infiltration disk. 2D axisymetric numerical simulations were conducted to evaluate the results of the experiment. Two different approaches were used: 1. Single-domain approach based on Richards' equation. 2. Dual-permeability approach based on two interacting water flow domains (matrix and preferential domains), each governed by one Richards' equation. In the first simulation, the reference parameters derived from retention curves obtained by standard pressure extractor method were taken as properties of the soil matrix. The input hydraulic parameters were subsequently inversely optimized. In the second approach, the saturated hydraulic conductivities of the preferential flow domain were optimized to fit rapid response of the tensiometers after the start of ponded infiltration. Objective function consisted of infiltration fluxes and suction pressure head data. The parameter estimator PEST coupled with the simulation code S2D_DUAL (Vogel et al.,2000) were used. Concerning the existence of preferential flow on investigated soil, the dual-permeability model gives a better picture of the flow regime. The research has been carried out within the projects VZ03 CEZ MSM

  18. Directional sensing and streaming in Dictyostelium aggregation.

    Science.gov (United States)

    Almeida, Sofia; Dilão, Rui

    2016-05-01

    We merge the Kessler-Levine simple discrete model for Dictyostelium cyclic adenosine monophosphate (cAMP) production and diffusion with the Dilão-Hauser directional sensing aggregation mechanism. The resulting compound model describes all the known transient patterns that emerge during Dictyostelium aggregation, which include the spontaneous formation of cAMP self-sustained target and spiral waves and streaming. We show that the streaming patterns depend on the speed of the amoebae, on the relaxation time for the production of cAMP, on the cAMP degradation rate, and on directional sensing. Moreover, we show that different signaling centers emerge during Dictyostelium aggregation.

  19. Antiplatelet aggregation principles from Ephemerantha lonchophylla.

    Science.gov (United States)

    Chen, C C; Huang, Y L; Teng, C M

    2000-05-01

    Bioactivity-directed separation led to the identification of four compounds, viz. denbinobin (1), 3,7-dihydroxy-2,4-dimethoxyphenanthrene (2), 3-methylgigantol (3), and erianthridin (4) from the ethanolic extract of Ephemerantha lonchophylla. Antiplatelet tests were carried out using 4 different aggregation inducers, viz. arachidonic acid (AA), thrombin, collagen and platelet activating factor (PAF). The results indicated that only compounds 2, 3, and 4 exhibited generally significant anti-aggregation activities with that against AA-induced aggregation being most effective. Estimated IC50, values in this regard for 2, 3, and 4 were 24 microM, 30 microM and 9 microM, respectively. PMID:10865460

  20. Synchronized Data Aggregation for Wireless Sensor Network

    DEFF Research Database (Denmark)

    Dnyaneshwar, Mantri; Prasad, Neeli R.; Prasad, Ramjee

    2014-01-01

    Wireless Sensor Networks (WSNs) are used for monitoring and data collection purposes. A key challenge in effective data collection is to schedule and synchronize the activities of the nodes with global clock. This paper proposes the Synchronized Data Aggregation Algorithm (SDA) using spanning tree...... mechanism. It provides network-wide time synchronization for sensor network. In the initial stage algorithm established the hierarchical structure in the network and then perform the pair - wise synchronization. SDA aggregate data with a global time scale throughout the network. The aggregated packets...

  1. Blood viscosity: influence of erythrocyte aggregation.

    Science.gov (United States)

    Chien, S; Usami, S; Dellenback, R J; Gregersen, M I; Nanninga, L B; Guest, M M

    1967-08-18

    The addition of purified canine or bovine fibrinogen to suspensions of canine erythocytes in Ringer solution caused an increase in viscosity and the formation of aggregates of erythocytes. Both of these effects became increasingly pronounced as the fibrinogen concentration was raised, and they approached plateaus with 1 gram of fibrinogen per 100 milliliters. An increase in shear rate (or shear stress) reduced both the effect on viscosity and the aggregate size. The data suggest that fibrinogen causes an increase in blood viscosity and a departure from Newtonian behavior by interacting with erythrocytes to form cell aggregates which can be dispersed by shear stress. PMID:17842794

  2. On Aggregating Human Capital Across Heterogeneous Cohorts

    DEFF Research Database (Denmark)

    Growiec, Jakub; Groth, Christian

    Based on a general framework for computing the aggregate human capital stock under heterogeneity across population cohorts, the paper derives aggregate human capital stocks in the whole population and in the labor force, and relates these variables to average years of schooling and average work...... experience. Under the scenarios considered here, the "macro-Mincer" (log-linear) relationship between aggregate human capital and average years of schooling is obtained only in cases which are inconsistent with heterogeneity in years of schooling and based on empirically implausible demographic survival laws...

  3. Aggregate Formed by a Cationic Fluorescence Probe

    Institute of Scientific and Technical Information of China (English)

    TIAN, Juan; SANG, Da-Yong; JI, Guo-Zhen

    2007-01-01

    The aggregation behavior of a cationic fluorescence probe 10-(4,7,10,13,16-pentaoxa-1-azacyclooctadecyl-methyl)anthracen-9-ylmethyl dodecanoate (1) was observed and studied by a fluorescence methodology in acidic and neutral conditions. By using the Py scale, differences between simple aggregates and micelles have been discussed. The stability of simple aggregates was discussed in terms of hydrophobic interaction and electrostatic repulsion. The absence of excimer emission of the anthrancene moiety of probe 1 in neutral condition was attributed to the photoinduced electron transfer mechanism instead of photodimerization.

  4. Linear aggregation theory in cell biology

    Energy Technology Data Exchange (ETDEWEB)

    Hill, T.L.

    1987-01-01

    This is an account of the theory, probability, and thermodynamics of linear aggregation. The emphasis is on basic principles illustrated by simple models, not on particular applications or polymers. The general physical aggregate systems - attached single-stranded polymers, single-stranded polymers modified by a second component, long multistranded polymers, attached multistranded polymers - are given extensive treatment. Also included are a discussion of the GTPase and ATPase activity accompanying the aggregation of microtubules and action, and the properties of the kinetic two-phase model of the end of a microtubule.

  5. Fractal aggregation of DNA after thermal denaturation

    Energy Technology Data Exchange (ETDEWEB)

    Yan Lifeng; Iwasaki, Hiroshi E-mail: iwasaki@sanken.osaka-u.ac.jp

    2004-05-01

    DNA thermal denaturation was observed by atomic force microscopy (AFM) on the surface of newly cleaved mica. It was found that at temperatures higher than the melting point, denaturation of DNA molecules took place and globular particles with size distribution were formed, and these particles could aggregate together to form fractal structures, which followed the diffusion limited aggregation (DLA) model. At 100 deg. C, degradation of DNA took place and small particles of about 20 nm in size were formed, and they also aggregated in fractal structures with a lower dimension. Evaporating speed of water affects the fractal dimension.

  6. Programming spiders, bots, and aggregators in Java

    CERN Document Server

    Heaton, Jeff

    2006-01-01

    The content and services available on the web continue to be accessed mostly through direct human control. But this is changing. Increasingly, users rely on automated agents that save them time and effort by programmatically retrieving content, performing complex interactions, and aggregating data from diverse sources. Programming Spiders, Bots, and Aggregators in Java teaches you how to build and deploy a wide variety of these agents-from single-purpose bots to exploratory spiders to aggregators that present a unified view of information from multiple user accounts. You will quickly build on

  7. Spectrum Aggregation: initial outcomes from SAMURAI project

    DEFF Research Database (Denmark)

    Vivier, Guillame; Badic, Biljana; Cattoni, Andrea Fabio;

    2011-01-01

    Multi-user MIMO and Spectrum Aggregation (also referred to Carrier Aggregation) are two key enablers of next generation wireless systems. Although those techniques were already quite well investigated at theoretical level, their practical implementation is not immediate and raises numerous...... challenges. The SAMURAI project aims at investigating such challenges as well as at providing realistic performance results. This paper presents first outcomes of the project, with a specific focus of Carrier Aggregation (CA). Two aspects are discussed: CA at PHY/RF level with implementation challenges. Then...

  8. A look at construction aggregates production

    Science.gov (United States)

    Willett, Jason Christopher

    2009-01-01

    Construction aggregates are defined as the combination of crushed stone and construction sand and gravel. Aggregates are one of the most accessible natural resources on Earth and one of the fundamental building blocks of our society. They have been used from the earliest times of our civilization for a variety of applications that have increased in number and complexity with time and technological progress. Despite the relatively low but increasing unit value of its basic products, the construction aggregates industry is a major contributor to and an indicator of the economic well-being of the nation.

  9. Reusing recycled aggregates in structural concrete

    Science.gov (United States)

    Kou, Shicong

    The utilization of recycled aggregates in concrete can minimize environmental impact and reduce the consumption of natural resources in concrete applications. The aim of this thesis is to provide a scientific basis for the possible use of recycled aggregates in structure concrete by conducting a comprehensive programme of laboratory study to gain a better understanding of the mechanical, microstructure and durability properties of concrete produced with recycled aggregates. The study also explored possible techniques to of improve the properties of recycled aggregate concrete that is produced with high percentages (≧ 50%) of recycled aggregates. These techniques included: (a) using lower water-to-cement ratios in the concrete mix design; (b) using fly ash as a cement replacement or as an additional mineral admixture in the concrete mixes, and (c) precasting recycled aggregate concrete with steam curing regimes. The characteristics of the recycled aggregates produced both from laboratory and a commercially operated pilot construction and demolition (C&D) waste recycling plant were first studied. A mix proportioning procedure was then established to produce six series of concrete mixtures using different percentages of recycled coarse aggregates with and without the use of fly ash. The water-to-cement (binder) ratios of 0.55, 0.50, 0.45 and 0.40 were used. The fresh properties (including slump and bleeding) of recycled aggregate concrete (RAC) were then quantified. The effects of fly ash on the fresh and hardened properties of RAC were then studied and compared with those RAC prepared with no fly ash addition. Furthermore, the effects of steam curing on the hardened properties of RAC were investigated. For micro-structural properties, the interfacial transition zones of the aggregates and the mortar/cement paste were analyzed by SEM and EDX-mapping. Moreover, a detailed set of results on the fracture properties for RAC were obtained. Based on the experimental

  10. Reynolds number influence on preferential concentration of heavy particles in turbulent flows

    Energy Technology Data Exchange (ETDEWEB)

    Obligado, Martin; Missaoui, Mahrane; Cartellier, Alain; Bourgoin, Mickaeel [Laboratoire des Ecoulements Geophysiques et Industriels, CNRS/UJF/G-INP UMR5519, BP53, 38041 Grenoble cedex 9 (France); Monchaux, Romain, E-mail: mickael.bourgoin@hmg.inpg.fr [Unite de mecanique, Ecole Nationale Superieure de Techniques Avancees, ParisTech, Chemin de la Huniere, 91761, Palaiseau Cedex (France)

    2011-12-22

    We present a study of the preferential concentration and clustering in homogeneous and isotropic turbulence. Using Voronoie diagrams, we have formerly quantified preferential concentration as a function of the Stokes number in moderate turbulence conditions up to Reynolds number based on Taylor microscale of the order of R{sub {lambda}} {approx} 120. Using an active grid recently implemented in our windtunnel, we investigate in the present study, the effect of Reynolds number on particles clustering, in the range R{sub {lambda}} {approx} 200 - 400.

  11. The clash of the Titans: how preferential attachment helps the survival of the smallest

    CERN Document Server

    Aich, Suman

    2014-01-01

    We examine the effects of preferential attachment on a model of competing clusters. In the original model, cluster masses grow at the expense of their neighbours; on a lattice, this is known to result in the asymptotic survival and indefinite growth of clusters which are isolated from each other. The presence of preferential attachment results in an inhomogeneous topology, where hubs monopolize the connections, while most other nodes are sparsely connected. Interestingly, this results in the protection of the less massive clusters from annihilation, to which the hubs are doomed.

  12. Compound Wiretap Channels

    Directory of Open Access Journals (Sweden)

    Kramer Gerhard

    2009-01-01

    Full Text Available Abstract This paper considers the compound wiretap channel, which generalizes Wyner's wiretap model to allow the channels to the (legitimate receiver and to the eavesdropper to take a number of possible states. No matter which states occur, the transmitter guarantees that the receiver decodes its message and that the eavesdropper is kept in full ignorance about the message. The compound wiretap channel can also be viewed as a multicast channel with multiple eavesdroppers, in which the transmitter sends information to all receivers and keeps the information secret from all eavesdroppers. For the discrete memoryless channel, lower and upper bounds on the secrecy capacity are derived. The secrecy capacity is established for the degraded channel and the semideterministic channel with one receiver. The parallel Gaussian channel is further studied. The secrecy capacity and the secrecy degree of freedom ( are derived for the degraded case with one receiver. Schemes to achieve the for the case with two receivers and two eavesdroppers are constructed to demonstrate the necessity of a prefix channel in encoder design. Finally, the multi-antenna (i.e., MIMO compound wiretap channel is studied. The secrecy capacity is established for the degraded case and an achievable is given for the general case.

  13. Compound Wiretap Channels

    Directory of Open Access Journals (Sweden)

    Shlomo Shamai (Shitz

    2009-01-01

    Full Text Available This paper considers the compound wiretap channel, which generalizes Wyner's wiretap model to allow the channels to the (legitimate receiver and to the eavesdropper to take a number of possible states. No matter which states occur, the transmitter guarantees that the receiver decodes its message and that the eavesdropper is kept in full ignorance about the message. The compound wiretap channel can also be viewed as a multicast channel with multiple eavesdroppers, in which the transmitter sends information to all receivers and keeps the information secret from all eavesdroppers. For the discrete memoryless channel, lower and upper bounds on the secrecy capacity are derived. The secrecy capacity is established for the degraded channel and the semideterministic channel with one receiver. The parallel Gaussian channel is further studied. The secrecy capacity and the secrecy degree of freedom (s.d.o.f. are derived for the degraded case with one receiver. Schemes to achieve the s.d.o.f. for the case with two receivers and two eavesdroppers are constructed to demonstrate the necessity of a prefix channel in encoder design. Finally, the multi-antenna (i.e., MIMO compound wiretap channel is studied. The secrecy capacity is established for the degraded case and an achievable s.d.o.f. is given for the general case.

  14. Acid Resistance of Concrete Containing Laterite Aggregate as Partial Coarse Aggregate Replacement

    Directory of Open Access Journals (Sweden)

    K. Muthusamy

    2014-05-01

    Full Text Available In Malaysia, issues of granite aggregate depletion in future due to increasing use in concrete industry and the availability of laterite aggregate locally has initiated studies on concrete produced using laterite aggregate as partial coarse aggregate replacement. Although, replacement of laterite aggregate up to 30% able to produce concrete with the targeted strength but durability of this concrete towards acid attack yet to be investigated. Thus, this study presents and discusses the performance of concrete consisting various percentage of laterite aggregate integrated as partial coarse aggregate replacement upon exposure to acidic environment. Mixes consisting various content of laterite aggregate as partial coarse aggregate replacement ranging from 0, 10, 20, 30, 40 and 50%, respectively were prepared in form of cubes and then subjected to water curing for 28 days before immersed in hydrochloric acid solution for 1800 h. Performance of the specimens were observed through mass loss and strength reduction. Generally, durability performance of concrete produced using up to 20% of laterite aggregate is comparable to plain concrete.

  15. p53 Aggregates penetrate cells and induce the co-aggregation of intracellular p53.

    Directory of Open Access Journals (Sweden)

    Karolyn J Forget

    Full Text Available Prion diseases are unique pathologies in which the infectious particles are prions, a protein aggregate. The prion protein has many particular features, such as spontaneous aggregation, conformation transmission to other native PrP proteins and transmission from an individual to another. Protein aggregation is now frequently associated to many human diseases, for example Alzheimer's disease, Parkinson's disease or type 2 diabetes. A few proteins associated to these conformational diseases are part of a new category of proteins, called prionoids: proteins that share some, but not all, of the characteristics associated with prions. The p53 protein, a transcription factor that plays a major role in cancer, has recently been suggested to be a possible prionoid. The protein has been shown to accumulate in multiple cancer cell types, and its aggregation has also been reproduced in vitro by many independent groups. These observations suggest a role for p53 aggregates in cancer development. This study aims to test the «prion-like» features of p53. Our results show in vitro aggregation of the full length and N-terminally truncated protein (p53C, and penetration of these aggregates into cells. According to our findings, the aggregates enter cells using macropinocytosis, a non-specific pathway of entry. Lastly, we also show that once internalized by the cell, p53C aggregates can co-aggregate with endogenous p53 protein. Together, these findings suggest prion-like characteristics for p53 protein, based on the fact that p53 can spontaneously aggregate, these aggregates can penetrate cells and co-aggregate with cellular p53.

  16. The theory of judgment aggregation: an introductory review

    OpenAIRE

    List, Christian

    2010-01-01

    This paper provides an introductory review of the theory of judgment aggregation. It introduces the paradoxes of majority voting that originally motivated the field, explains several key results on the impossibility of propositionwise judgment aggregation, presents a pedagogical proof of one of those results, discusses escape routes from the impossibility and relates judgment aggregation to some other salient aggregation problems, such as preference aggregation, abstract aggregation and proba...

  17. Striped Cucumber Beetle (Coleoptera: Chrysomelidae) Aggregation in Response to Cultivar and Flowering.

    Science.gov (United States)

    Gardner, Jeffrey; Hoffmann, Michael P; Mazourek, Michael

    2015-04-01

    The striped cucumber beetle [Acalymma vittatum (F.)] is a specialist pest of cucurbits throughout its range in the United States and Canada. Improved integrated pest management options are needed across the pest's range, especially on organic farms where there are few effective controls. Trap cropping in cucurbits is an option, but there are significant challenges to the technique. Because cucurbit flowers are highly attractive to the beetles, four field experiments tested whether cultivar and phenology interact to preferentially aggregate beetles. The first experiment tested the hypothesis that cucurbit flowers were more attractive to striped cucumber beetles than was foliage. The second experiment tested whether there were differences in beetle aggregation between two relatively attractive cultivars. The third and fourth experiments were factorial designs with two plant cultivars and two levels of flowering to specifically test for an interaction of cultivar and flowering. Results indicated that flowers were more attractive than foliage, beetle aggregation was affected by plant cultivar, and that there was an interaction of cultivar with flowering. We conclude that a single cultivar may be sufficient to serve as a generic trap crop to protect a wide variety of cucurbits. PMID:26313184

  18. Polyglutamine Expansion Alters the Dynamics and Molecular Architecture of Aggregates in Dentatorubropallidoluysian Atrophy*

    Science.gov (United States)

    Hinz, Justyna; Lehnhardt, Lothar; Zakrzewski, Silke; Zhang, Gong; Ignatova, Zoya

    2012-01-01

    Preferential accumulation of mutant proteins in the nucleus has been suggested to be the molecular culprit that confers cellular toxicity in the neurodegenerative disorders caused by polyglutamine (polyQ) expansion. Here, we use dynamic imaging approaches, orthogonal cross-seeding, and composition analysis to examine the dynamics and structure of nuclear and cytoplasmic inclusions of atrophin-1, implicated in dentatorubropallidoluysian atrophy, a polyQ-based disease with complex clinical features. Our results reveal a large heterogeneity in the dynamics of the nuclear inclusions compared with the compact and immobile cytoplasmic aggregates. At least two types of inclusions of expanded atrophin-1 with different mobility of the molecular species and ability to exchange with the surrounding monomer pool coexist in the nucleus. Intriguingly, the enrichment of nuclear inclusions with slow dynamics parallels changes in the aggregate core architecture that are dominated by the polyQ stretch. We propose that the observed complexity in the dynamics of the nuclear inclusions provides a molecular explanation for the enhanced cellular toxicity of the nuclear aggregates in polyQ-based neurodegeneration. PMID:22134925

  19. Channel capacity and error exponents of variable rate adaptive channel coding for Rayleigh fading channels

    OpenAIRE

    Lau, KN

    1999-01-01

    We have evaluated the information theoretical performance of variable rate adaptive channel coding for Rayleigh fading channels. The channel states are detected at the receiver and fed back to the transmitter by means of a noiseless feedback link. Based on the channel state informations, the transmitter can adjust the channel coding scheme accordingly. Coherent channel and arbitrary channel symbols with a fixed average transmitted power constraint are assumed. The channel capacity and the err...

  20. A Survey of Distributed Data Aggregation Algorithms

    CERN Document Server

    Jesus, Paulo; Almeida, Paulo Sérgio

    2011-01-01

    Distributed data aggregation is an important task, allowing the decentralized determination of meaningful global properties, that can then be used to direct the execution of other applications. The resulting values result from the distributed computation of functions like COUNT, SUM and AVERAGE. Some application examples can found to determine the network size, total storage capacity, average load, majorities and many others. In the last decade, many different approaches have been proposed, with different trade-offs in terms of accuracy, reliability, message and time complexity. Due to the considerable amount and variety of aggregation algorithms, it can be difficult and time consuming to determine which techniques will be more appropriate to use in specific settings, justifying the existence of a survey to aid in this task. This work reviews the state of the art on distributed data aggregation algorithms, providing three main contributions. First, it formally defines the concept of aggregation, characterizin...

  1. EFFECT OF AGGREGATION ON VIBRIO CHOLERA INACTIVATION

    Science.gov (United States)

    Extensive research has shown that microorganisms exhibit increased resistance due to clumping, aggregation, particle association or modification of antecedent growth conditions. uring the course of investigating a major waterborne V. Cholerae outbreak in Peru, U.S. EPA investigat...

  2. Modeling In-Network Aggregation in VANETs

    NARCIS (Netherlands)

    Dietzel, Stefan; Kargl, Frank; Heijenk, Geert; Schaub, Florian

    2011-01-01

    The multitude of applications envisioned for vehicular ad hoc networks requires efficient communication and dissemination mechanisms to prevent network congestion. In-network data aggregation promises to reduce bandwidth requirements and enable scalability in large vehicular networks. However, most

  3. Silt-clay aggregates on Mars

    Science.gov (United States)

    Greeley, R.

    1979-01-01

    Viking observations suggest abundant silt and clay particles on Mars. It is proposed that some of these particles agglomerate to form sand size aggregates that are redeposited as sandlike features such as drifts and dunes. Although the binding for the aggregates could include salt cementation or other mechanisms, electrostatic bonding is considered to be a primary force holding the aggregates together. Various laboratory experiments conducted since the 19th century, and as reported here for simulated Martian conditions, show that both the magnitude and sign of electrical charges on windblown particles are functions of particle velocity, shape and composition, atmospheric pressure, atmospheric composition and other factors. Electrical charges have been measured for saltating particles in the wind tunnel and in the field, on the surfaces of sand dunes, and within dust clouds on earth. Similar, and perhaps even greater, charges are proposed to occur on Mars, which could form aggregates of silt and clay size particles

  4. Trade Openness and Aggregate Productive Efficiency

    OpenAIRE

    Georgios E. Chortareas; Evangelia Desli; Theodore Pelagidis

    2003-01-01

    We consider whether openness is related to the aggregate technical efficiency in the OECD countries. We obtain efficiency measures using Data Envelopment Analysis and we find that our measure of openness is positively related to the technical efficiency scores.

  5. Blue-emitting pyrene-based aggregates.

    Science.gov (United States)

    Valera, Jorge S; Calbo, Joaquín; Gómez, Rafael; Ortí, Enrique; Sánchez, Luis

    2015-06-25

    The supramolecular polymerization of pyrene imidazoles 1 and 2, governed by H-bonding and C-H···π interactions, yields aggregates showing the characteristic bluish emission pattern of pyrene-based monomers.

  6. Salt-induced aggregation of stiff polyelectrolytes

    International Nuclear Information System (INIS)

    Molecular dynamics simulation techniques are used to study the process of aggregation of highly charged stiff polyelectrolytes due to the presence of multivalent salt. The dominant kinetic mode of aggregation is found to be the case of one end of one polyelectrolyte meeting others at right angles, and the kinetic pathway to bundle formation is found to be similar to that of flocculation dynamics of colloids as described by Smoluchowski. The aggregation process is found to favor the formation of finite bundles of 10-11 filaments at long times. Comparing the distribution of the cluster sizes with the Smoluchowski formula suggests that the energy barrier for the aggregation process is negligible. Also, the formation of long-lived metastable structures with similarities to the raft-like structures of actin filaments is observed within a range of salt concentration.

  7. Inverted aggregates of luminescent ruthenium metallosurfactants

    NARCIS (Netherlands)

    D. Domínguez-Gutiérrez; G. de Paoli; A. Guerrero-Martinez; G. Ginocchietti; D. Ebeling; E. Eiser; L. De Cola; C.J. Elsevier

    2008-01-01

    Metallosurfactants and their resulting aggregates combine unique spectroscopic and reactivity properties due to space confinement. We have found the requirements to obtain the first inverted micelles with luminescent metallosurfactants. The compounds possess several long linear chains that favour th

  8. Fish Aggregation Sites in the Florida Keys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Spawning aggregations are an important event in the life-history of many coral reef fish species. During short time periods (typically during full moons), fish will...

  9. Suspensions of colloidal particles and aggregates

    CERN Document Server

    Babick, Frank

    2016-01-01

    This book addresses the properties of particles in colloidal suspensions. It has a focus on particle aggregates and the dependency of their physical behaviour on morphological parameters. For this purpose, relevant theories and methodological tools are reviewed and applied to selected examples. The book is divided into four main chapters. The first of them introduces important measurement techniques for the determination of particle size and interfacial properties in colloidal suspensions. A further chapter is devoted to the physico-chemical properties of colloidal particles—highlighting the interfacial phenomena and the corresponding interactions between particles. The book’s central chapter examines the structure-property relations of colloidal aggregates. This comprises concepts to quantify size and structure of aggregates, models and numerical tools for calculating the (light) scattering and hydrodynamic properties of aggregates, and a discussion on van-der-Waals and double layer interactions between ...

  10. Geopolymerization of lightweight aggregate waste

    Directory of Open Access Journals (Sweden)

    Labrincha, J. A.

    2008-09-01

    Full Text Available Geopolymerization is a viable way to process and re-use alumino-silicate industrial waste while producing highstrength, high chemical inertia materials that can effectively immobilize other industrial by-products, and even hazardous waste. In this study industrial waste from different stages of the manufacture of lightweight expanded clay aggregate was characterized for its possible transformation, via alkali activation, to geopolymers. The ultimate aim was to assess the possibility of using such geopolymers to develop thermal and acoustic insulation panels. The containment of hazardous materials is another important application for these new materials. Geopolymers were prepared for this study with different particles size distributions and activator concentrations. Their mechanical properties, composition and microstructure were characterized and a material with promising insulating properties was produced. A preliminary analysis was conducted of the salt formation observed in these geopolymers, the chief drawback to their use.La geopolimerización es una manera viable para procesar y agregar valor a los residuos industriales de alumino-silicato dando lugar a materiales con elevadas resistencias mecánmicas, alta inercia química y que permiten encapsular otros residuos, incluso peligrosos. Los residuos industriales que proceden de diversos tipos de arcillas para la fabricación de áridos ligeros se han caracterizado para la producción de geopolímeros mediante el proceso de ataque alcalino. Su incorporación en una matriz geopolimérica permite la posibilidad de desarrollo de paneles de aislamiento (térmico y acústico. Además, la inmovilización de materiales peligrosos es un logro adicional importante. Los geopolímeros se han producido con fórmulas diferentes y se han caracterizado sus propiedades mecánicas, composición y microestructura, para dar lugar a una composición interesante con propiedades aislantes. Se ha llevado a cabo

  11. Quantum broadcast channels

    CERN Document Server

    Yard, J; Devetak, I; Yard, Jon; Hayden, Patrick; Devetak, Igor

    2006-01-01

    We analyze quantum broadcast channels, which are quantum channels with a single sender and many receivers. Focusing on channels with two receivers for simplicity, we generalize a number of results from the network Shannon theory literature which give the rates at which two senders can receive a common message, while a personalized one is sent to one of them. Our first collection of results applies to channels with a classical input and quantum outputs. The second class of theorems we prove concern sending a common classical message over a quantum broadcast channel, while sending quantum information to one of the receivers. The third group of results we obtain concern communication over an isometry, giving the rates at quantum information can be sent to one receiver, while common quantum information is sent to both, in the sense that tripartite GHZ entanglement is established. For each scenario, we provide an additivity proof for an appropriate class of channels, yielding single-letter characterizations of the...

  12. Spatial and temporal characteristics of grouper spawning aggregations in marine protected areas in Palau, western Micronesia

    Science.gov (United States)

    Golbuu, Yimnang; Friedlander, Alan M.

    2011-04-01

    In Palau, Ngerumekaol and Ebiil Channels are spawning aggregation sites that have been protected from fishing since 1976 and 2000, respectively. Groupers and other targeted fisheries species were monitored monthly over a 1.5 year period at these two spawning aggregations and two nearby exploited reference sites where grouper formerly aggregated to spawn. At the protected aggregation sites, three grouper species ( Plectropomus areolatus, Epinephelus polyphekadion, and Epinephelus fuscoguttatus) accounted for 78% of the abundance and 85% of the biomass of all resource species surveyed but comprised <1% of the total abundance and biomass at reference sites not protected from fishing that formally harbored spawning aggregations. Abundance and biomass of grouper species pooled were 54% and 72% higher, respectively, at Ngerumekaol compared to Ebiil. Comparisons with data from the same locations in 1995-1996 showed order of magnitude declines in abundance of E. polyphekadion at both locations. The lower numbers of E. fuscoguttatus and the near absence of E. polyphekadion at Ebiil may reflect the effects of previous and current overexploitation.

  13. Control of aggregation-induced emission by DNA hybridization

    OpenAIRE

    Li, Shaoguang; Langenegger, Simon Matthias; Häner, Robert

    2013-01-01

    Aggregation-induced emission (AIE) was studied by hybridization of dialkynyl-tetraphenylethylene (DATPE) modified DNA strands. Molecular aggregation and fluorescence of DATPEs are controlled by duplex formation.

  14. HIPPI and Fibre Channel

    International Nuclear Information System (INIS)

    The High-Performance Parallel Interface (HIPPI) and Fibre Channel are near-gigabit per second data communications interfaces being developed in ANSI standards Task Group X3T9.3. HIPPI is the current interface of choice in the high-end and supercomputer arena, and Fibre Channel is a follow-on effort. HIPPI came from a local area network background, and Fibre Channel came from a mainframe to peripheral interface background

  15. Consistent GDP Aggregation and Purchasing Power Parity

    OpenAIRE

    Dumagan, Jesus C.

    2012-01-01

    Consistent aggregation ensures that real GDP level and growth do not change as the existing GDP components are merely rearranged. Otherwise, level or growth changes are spurious. This paper proposes a framework for consistent aggregation where components are converted to "purchasing power parity" (PPP) values that "add up exactly" to the same real GDP regardless of the grouping of components. This PPP framework applies to GDP either in constant prices or in chained prices. PPP is applied to U...

  16. An Analysis of Rank Aggregation Algorithms

    OpenAIRE

    Lv, Gattaca

    2014-01-01

    Rank aggregation is an essential approach for aggregating the preferences of multiple agents. One rule of particular interest is the Kemeny rule, which maximises the number of pairwise agreements between the final ranking and the existing rankings. However, Kemeny rankings are NP-hard to compute. This has resulted in the development of various algorithms. Fortunately, NP-hardness may not reflect the difficulty of solving problems that arise in practice. As a result, we aim to demonstrate that...

  17. The materials science of protein aggregation

    OpenAIRE

    Cox, D L; Lashuel, H. A.; Lee, K. Y. C.; Singh, R. R. R.

    2005-01-01

    Numerous human diseases are associated with conformational change and aggregation of proteins, including Alzheimer's, Parkinson's, prion diseases (such as mad cow disease), familial amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease), Huntington's, and type II (mature onset) diabetes. In many cases, it has been demonstrated that conformational change and aggregation can occur outside living cells and complex biochemical networks. Hence, approaches from materials and physical science ...

  18. Two Scale Model for Aggregation and Etching

    CERN Document Server

    John, G C; John, George C.; Singh, Vijay A.

    1995-01-01

    We propose a dual scale drift-diffusion model for interfacial growth and etching processes. The two scales are: (i) a depletion layer width surrounding the aggregate and (ii) a drift length.The interplay between these two antithetical scales yields a variety of distinct morphologies reported in electrochemical deposition of metals, viscous fingering in fluids and in porous silicon formation. Further, our algorithm interpolates between existing growth models (diffusion limited aggregation, ballistic deposition and Eden) for limiting values of these variables.

  19. Aggregate Implications of Micro Asset Market Segmentation

    OpenAIRE

    Chris Edmond; Pierre-Olivier Weill

    2011-01-01

    This paper develops a consumption-based asset pricing model to explain and quantify the aggregate implications of a frictional financial system, comprised of many financial markets partially integrated with one another. Each of our micro financial market's is inhabited by traders who are specialized in that markets type of asset. We specify exogenously the level of segmentation that ultimately determines how much idiosyncratic risk traders bear in their micro market and derive aggregate asset...

  20. Familial Aggregation and Childhood Blood Pressure

    OpenAIRE

    Wang, Xiaoling; Xu, Xiaojing; Su, Shaoyong; Snieder, Harold

    2015-01-01

    There is growing concern about elevated blood pressure (BP) in children. The evidence for familial aggregation of childhood BP is substantial. Twin studies have shown that a large part of the familial aggregation of childhood BP is due to genes. The first part of this review provides the latest progress in gene finding for childhood BP, focusing on the combined effects of multiple loci identified from the genome-wide association studies on adult BP. We further review the evidence on the contr...

  1. A Visibility Graph Averaging Aggregation Operator

    OpenAIRE

    Chen, Shiyu; Hu, Yong; Mahadevan, Sankaran; Deng, Yong

    2013-01-01

    The problem of aggregation is considerable importance in many disciplines. In this paper, a new type of operator called visibility graph averaging (VGA) aggregation operator is proposed. This proposed operator is based on the visibility graph which can convert a time series into a graph. The weights are obtained according to the importance of the data in the visibility graph. Finally, the VGA operator is used in the analysis of the TAIEX database to illustrate that it is practical and compare...

  2. The Use of Calcium Channel Blockers in Skin Diseases

    Directory of Open Access Journals (Sweden)

    Özge Uzun

    2013-05-01

    Full Text Available Calcium channel blockers are a group of drugs often used to treat cardiovascular diseases, such as hypertension, angina, peripheral vascular disorders and some arrhythmias. These drugs may suppress the growth and proliferation of vascular smooth muscle cells and fibroblasts, and inhibit the synthesis of extracellular-matrix proteins,such as collagen, fibronectin, proteoglycans. Some calcium channel blockers also have immunomodulatory or dysregulatory effects on lymphocytes and can suppress superoxide generation and phagocytic activity of neutrophils. Moreover, mast cell degranulation and platelet aggregation may also be impaired. On account of these properties, calcium channel blockers have also been used for the prevention and treatment of various dermatologic diseases. In this review, we evaluated the use of calcium channel blockers in various dermatologic diseases, such as Raynaud’s phenomenon, chilblains, chronic anal fissures, vulvodynia, keloids and burn scars, calcinosis cutis, and leiomyoma.

  3. Particle aggregation mechanisms in ionic liquids.

    Science.gov (United States)

    Szilagyi, Istvan; Szabo, Tamas; Desert, Anthony; Trefalt, Gregor; Oncsik, Tamas; Borkovec, Michal

    2014-05-28

    Aggregation of sub-micron and nano-sized polystyrene latex particles was studied in room temperature ionic liquids (ILs) and in their water mixtures by time-resolved light scattering. The aggregation rates were found to vary with the IL-to-water molar ratio in a systematic way. At the water side, the aggregation rate is initially small, but increases rapidly with increasing IL content, and reaches a plateau value. This behaviour resembles simple salts, and can be rationalized by the competition of double-layer and van der Waals forces as surmised by the classical theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO). At the IL side, aggregation slows down again. Two generic mechanisms could be identified to be responsible for the stabilization in ILs, namely viscous stabilization and solvation stabilization. Viscous stabilization is important in highly viscous ILs, as it originates from the slowdown of the diffusion controlled aggregation due to the hindrance of the diffusion in a viscous liquid. The solvation stabilization mechanism is system specific, but can lead to a dramatic slowdown of the aggregation rate in ILs. This mechanism is related to repulsive solvation forces that are operational in ILs due to the layering of the ILs close to the surfaces. These two stabilization mechanisms are suspected to be generic, as they both occur in different ILs, and for particles differing in surface functionalities and size. PMID:24727976

  4. Influence of Phenylalanine on Carotenoid Aggregation

    Science.gov (United States)

    Lu, L.; Ni, X.; Luo, X.

    2015-01-01

    The carotenoids lutein and β-carotene form, in 1:1 ethanol-water mixtures H-aggregates, of different strengths. The effects of phenylalanine on these aggregates were recorded by UV-Vis absorption, steady-state fluorescence, and Raman spectra. The H-aggregate of lutein was characterized by a large 78 nm blue shift in the absorption spectra, confirming the strong coupling between hydroxyl groups of adjacent molecules. The 15 nm blue shift in the β-carotene mixture also indicates that it was assembled by weak coupling between polyenes. After adding phenylalanine, the reducing absorption strength of the aggregates of lutein and reappearance of vibrational substructure indicate that the hydroxyl and amino groups of phenylalanine may coordinate to lutein and disaggregate the H-aggregates. However, phenylalanine had no effect on aggregates of β-carotene. The Raman spectra show three bands of carotenoids whose intensities decreased with increasing phenylalanine concentration. The frequency of ν1 corresponding to the length of the conjugated region was more sensitive to the solution of lutein. This coordination of phenylalanine to lutein could increase the length of the conjugated region. In addition, phenylalanine significantly affected the excited electronic states of carotenoids, which were crucial in the energy transfer from carotenoids to chlorophyll a in vivo.

  5. An Identity Based Aggregate Signature from Pairings

    Directory of Open Access Journals (Sweden)

    Yike Yu

    2011-04-01

    Full Text Available An aggregate signature is a useful digital signature that supports aggregation: Given n signatures on n distinct messages from n distinct users, aggregate signature scheme is possible to aggregate all these signature into a single short signature. This single signature, along with the n original messages will convince any verifier that the n users did indeed sign the n original messages respectively (i.e., for i=1,...,n user i signed message  mi. In this paper, we propose an identity based aggregate signature scheme which requires constant pairing operations in the verification and the size of aggregate signature is independent of the number of signers. We prove that the proposed signature scheme is secure against existential forgery under adaptively chosen message and identity attack in the random oracle model assuming the intractability of the computational Diffie-Hellman problem.

  6. Growth hormone aggregates in the rat adenohypophysis

    Science.gov (United States)

    Farrington, M.; Hymer, W. C.

    1990-01-01

    Although it has been known for some time that GH aggregates are contained within the rat anterior pituitary gland, the role that they might play in pituitary function is unknown. The present study examines this issue using the technique of Western blotting, which permitted visualization of 11 GH variants with apparent mol wt ranging from 14-88K. Electroelution of the higher mol wt variants from gels followed by their chemical reduction with beta-mercaptoethanol increased GH immunoassayability by about 5-fold. With the blot procedure we found 1) that GH aggregates greater than 44K were associated with a 40,000 x g sedimentable fraction; 2) that GH aggregates were not present in glands from thyroidectomized rats, but were in glands from the thyroidectomized rats injected with T4; 3) that GH aggregates were uniquely associated with a heavily granulated somatotroph subpopulation isolated by density gradient centrifugation; and 4) that high mol wt GH forms were released from the dense somatotrophs in culture, since treatment of the culture medium with beta-mercaptoethanol increased GH immunoassayability by about 5-fold. Taken together, the results show that high mol wt GH aggregates are contained in secretory granules of certain somatotrophs and are also released in aggregate form from these cells in vitro.

  7. Topological Properties and Transition Features Generated by a New Hybrid Preferential Model

    Institute of Scientific and Technical Information of China (English)

    FANG Jin-Qing; LIANG Yong

    2005-01-01

    @@ A new hybrid preferential model (HPM) is proposed for generating both scale-free and small world properties.The topological transition features in the HPM from random preferential attachment to deterministic preferential attachment are investigated. It is found that the exponents γ of the power law are very sensitive to the hybrid ratio (d/r) of determination to random attachment, and γincreases as the ratio d/r increases. It is also found that there exists a threshold at d/r = 1/1, beyond which γ increases rapidly and can tend to infinity if there is no random preferential attachment (r = 0), which implies that the power law scaling disappears completely.Moreover, it is also found that when the ratio d/r increases, the average path length L is decreased, while the average clustering coefficient C is increased. Compared to the BA model and random graph, the new HPM has both the smallest L and the biggest C, which is consistent with most real-world growing networks.

  8. Exploring the antecedents of preferential customer treatment by suppliers: a mixed methods approach

    NARCIS (Netherlands)

    Huttinger, Lisa; Schiele, H.; Schröer, Dennis

    2014-01-01

    Purpose – This paper aims to understand the factors that influence a supplier’s choice to treat selected customers more preferentially than others. Suppliers often lack the resources to treat all their customers equally, instead having to make choices to treat some customers as preferred. Empirical

  9. Preferential Attachment Model with Degree Bound and its Application to Key Predistribution in WSN

    CERN Document Server

    Ruj, Sushmita

    2016-01-01

    Preferential attachment models have been widely studied in complex networks, because they can explain the formation of many networks like social networks, citation networks, power grids, and biological networks, to name a few. Motivated by the application of key predistribution in wireless sensor networks (WSN), we initiate the study of preferential attachment with degree bound. Our paper has two important contributions to two different areas. The first is a contribution in the study of complex networks. We propose preferential attachment model with degree bound for the first time. In the normal preferential attachment model, the degree distribution follows a power law, with many nodes of low degree and a few nodes of high degree. In our scheme, the nodes can have a maximum degree $d_{\\max}$, where $d_{\\max}$ is an integer chosen according to the application. The second is in the security of wireless sensor networks. We propose a new key predistribution scheme based on the above model. The important features ...

  10. Preferential processing of visual trauma-film reminders predicts subsequent intrusive memories

    NARCIS (Netherlands)

    Verwoerd, J.R.L.; Wessel, I.; De Jong, P.J.; Nieuwenhuis, Maurice

    2009-01-01

    This study used an analogue design to test the hypothesis that preferential processing of visual trauma reminders in the aftermath of a stressful or traumatic event gives rise to subsequent intrusive memories. Shortly after the presentation of a stressful film fragment, participants (n=36) were aske

  11. Guangxi Canceling Preferential Power Price for High Energy Consumption Including Aluminum Enterprises

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Guangxi has carried out the policy of differen- tiated power price earnestly.At the end of 2007,the price bureau of the autonomous re- gion has unveiled the policy of the cancellation of preferential electricity price for high energy consumption enterprises.

  12. Emergency abdominal aortic aneurysm repair with a preferential endovascular strategy : Mortality and cost-effectiveness analysis

    NARCIS (Netherlands)

    Kapma, Marten R.; Groen, Henk; Oranen, Bjorn I.; van der Hilst, Christian S.; Tielliu, Ignace F.; Zeebregts, Clark J.; Prins, Ted R.; van den Dungen, Jan J.; Verhoeven, Eric L.

    2007-01-01

    Purpose: To assess mortality and treatment costs of a new management protocol with preferential use of emergency endovascular aneurysm repair (eEVAR) for acute abdominal aortic aneurysm (AAA). Methods: From September 2003 until February 2005, 49 consecutive patients (45 men; mean age 71 years) with

  13. Preferential Trade Agreements and the Law and Politics of GATT Article XXIV

    DEFF Research Database (Denmark)

    Alavi, Amin

    2010-01-01

    The tasks Preferential Trade Agreements (PTAs) perform are expressed in their scope and covered issues, thus in order to be WTO compatible these aspects of PTAs should comply with the relevant WTO rules. This paper examines which aspects of PTAs can violate these rules and therefore can be challe...

  14. Preferential flow of bromide, bentazon, and imidacloprid in a Dutch clay soil

    NARCIS (Netherlands)

    Scorza Júnior, R.P.; Smelt, J.H.; Boesten, J.J.T.I.; Hendriks, R.F.A.; Zee, van der S.E.A.T.M.

    2004-01-01

    Leaching to ground water and tile drains are important parts of the environmental assessment of pesticides. The aims of the present study were to (i) assess the significance of preferential flow for pesticide leaching under realistic worst-case conditions for Dutch agriculture (soil profile with thi

  15. Preferential Hiring and Reverse Discrimination in Favor of Blacks: A Moral Analysis.

    Science.gov (United States)

    Husak, Douglas N.

    1978-01-01

    Sketches a broad and general defense of the constitutionality of some kinds of preferential admissions and hiring programs in favor of Blacks by constructing a moral justification of these practices. Available from American Journal of Jurisprudence, Notre Dame Law School, Notre Dame, Indiana 46556; reprint, $1.00. (Author/IRT)

  16. An elaboration of theory about preventing outbreaks in homogeneous populations to include heterogeneity or preferential mixing.

    Science.gov (United States)

    Feng, Zhilan; Hill, Andrew N; Smith, Philip J; Glasser, John W

    2015-12-01

    The goal of many vaccination programs is to attain the population immunity above which pathogens introduced by infectious people (e.g., travelers from endemic areas) will not cause outbreaks. Using a simple meta-population model, we demonstrate that, if sub-populations either differ in characteristics affecting their basic reproduction numbers or if their members mix preferentially, weighted average sub-population immunities cannot be compared with the proportionally-mixing homogeneous population-immunity threshold, as public health practitioners are wont to do. Then we review the effect of heterogeneity in average per capita contact rates on the basic meta-population reproduction number. To the extent that population density affects contacts, for example, rates might differ in urban and rural sub-populations. Other differences among sub-populations in characteristics affecting their basic reproduction numbers would contribute similarly. In agreement with more recent results, we show that heterogeneous preferential mixing among sub-populations increases the basic meta-population reproduction number more than homogeneous preferential mixing does. Next we refine earlier results on the effects of heterogeneity in sub-population immunities and preferential mixing on the effective meta-population reproduction number. Finally, we propose the vector of partial derivatives of this reproduction number with respect to the sub-population immunities as a fundamentally new tool for targeting vaccination efforts. PMID:26375548

  17. Preferential orientation of biological apatite in normal and osteoporotic human vertebral trabeculae

    Science.gov (United States)

    Miyabe, S.; Ishimoto, T.; Nakano, T.

    2009-05-01

    The preferential orientation of biological apatite (BAp) is a possible bone quality parameter for the comparison of the bone mechanical property. The preferential BAp orientation undergoes sensitive changes according to the change in the in vivo stress distribution, bone turnover rate etc., resulting in a variation of bone function. Osteoporosis is a metabolic bone disease characterized by reduced bone mass and deterioration of bone microstructure. The effect of osteoporosis on the preferential BAp orientation is however unknown. In this study, a microbeam-X-ray diffraction (μXRD) study was carried out on a trabecula extracted from osteoporotic and normal human vertebral bones and the degree of orientation for the BAp c-axis along its craniocaudal axis was analysed based on our previous report. A micro-computed tomography (μCT) measurement was also performed to analyze trabecular density and structure. In osteoporotic human vertebra, the trabecular number is markedly lower than that in normal vertebra. To sustain increased stress because of bone loss, the primary trabeculae, which are aligned parallel to the craniocaudal axis, tend to selectively remain while the secondary trabeculae, which are perpendicular to the craniocaudal axis, mostly disappear. Moreover, the primary trabecula from osteoporotic vertebra showed a significantly higher degree of BAp preferential orientation than the normal bone. This suggests that the remaining primary trabecula in osteoporotic vertebra is further reinforced by an increase in applied stress in vivo by enhancing the preferred BAp c-axis orientation along the trabecular direction.

  18. Betweenness centrality as a driver of preferential attachment in the evolution of research collaboration networks

    NARCIS (Netherlands)

    A. Abbasi; L. Hossain; L. Leydesdorff

    2012-01-01

    We analyze whether preferential attachment in scientific coauthorship networks is different for authors with different forms of centrality. Using a complete database for the scientific specialty of research about "steel structures," we show that betweenness centrality of an existing node is a signif

  19. Quantification of the influence of preferential flow on slope stability using a numerical modeling approach (discussions)

    NARCIS (Netherlands)

    Shao, W.; Bogaard, T.A.; Bakker, M.; Greco, R.

    2014-01-01

    The effect of preferential flow on the stability of landslides is studied through numerical simulation of two types of rainfall events on a hypothetical hillslope. A model is developed that consists of two parts. The first part is a model for combined saturated/unsaturated subsurface flow and is use

  20. Influence of sampling strategy on detecting preferential flow paths in water-repellent sand

    NARCIS (Netherlands)

    Ritsema, C.J.; Dekker, L.W.

    1996-01-01

    A sample spacing up to 22 cm over a distance of several metres is just sufficient to collect information about preferential flow paths in a water-repellent sandy soil. When larger sample spacings were used, the water content distributions became more horizontally stratified. Increasing the sample si

  1. Quantification of the influence of preferential flow on slope stability using a numerical modelling approach

    NARCIS (Netherlands)

    Shao, W.; Bogaard, T.A.; Bakker, M.; Greco, R.

    2015-01-01

    The effect of preferential flow on the stability of landslides is studied through numerical simulation of two types of rainfall events on a hypothetical hillslope. A model is developed that consists of two parts. The first part is a model for combined saturated/unsaturated subsurface flow and is use

  2. Influence of Aggregate Wettability with Different Lithology Aggregates on Concrete Drying Shrinkage

    OpenAIRE

    Yuanchen Guo; Jueshi Qian; Xue Wang; Zhengyi Yan; Huadong Zhong

    2015-01-01

    The correlation of the wettability of different lithology aggregates and the drying shrinkage of concrete materials is studied, and some influential factors such as wettability and wetting angle are analyzed. A mercury porosimeter is used to measure the porosities of different lithology aggregates accurately, and the pore size ranges that significantly affect the drying shrinkage of different lithology aggregate concretes are confirmed. The pore distribution curve of the different coarse aggr...

  3. Effects of tau domain-specific antibodies and intravenous immunoglobulin on tau aggregation and aggregate degradation.

    Science.gov (United States)

    Esteves-Villanueva, Jose O; Trzeciakiewicz, Hanna; Loeffler, David A; Martić, Sanela

    2015-01-20

    Tau pathology, including neurofibrillary tangles, develops in Alzheimer's disease (AD). The aggregation and hyperphosphorylation of tau are potential therapeutic targets for AD. Administration of anti-tau antibodies reduces tau pathology in transgenic "tauopathy" mice; however, the optimal tau epitopes and conformations to target are unclear. Also unknown is whether intravenous immunoglobulin (IVIG) products, currently being evaluated in AD trials, exert effects on pathological tau. This study examined the effects of anti-tau antibodies targeting different tau epitopes and the IVIG Gammagard on tau aggregation and preformed tau aggregates. Tau aggregation was assessed by transmission electron microscopy and fluorescence spectroscopy, and the binding affinity of the anti-tau antibodies for tau was evaluated by enzyme-linked immunosorbent assays. Antibodies used were anti-tau 1-150 ("D-8"), anti-tau 259-266 ("Paired-262"), anti-tau 341-360 ("A-10"), and anti-tau 404-441 ("Tau-46"), which bind to tau's N-terminus, microtubule binding domain (MBD) repeat sequences R1 and R4, and the C-terminus, respectively. The antibodies Paired-262 and A-10, but not D-8 and Tau-46, reduced tau fibrillization and degraded preformed tau aggregates, whereas the IVIG reduced tau aggregation but did not alter preformed aggregates. The binding affinities of the antibodies for the epitope for which they were specific did not appear to be related to their effects on tau aggregation. These results confirm that antibody binding to tau's MBD repeat sequences may inhibit tau aggregation and indicate that such antibodies may also degrade preformed tau aggregates. In the presence of anti-tau antibodies, the resulting tau morphologies were antigen-dependent. The results also suggested the possibility of different pathways regulating antibody-mediated inhibition of tau aggregation and antibody-mediated degradation of preformed tau aggregates. PMID:25545358

  4. Incorporating preferential flow into a 3D model of a forested headwater catchment

    Science.gov (United States)

    Glaser, Barbara; Jackisch, Conrad; Hopp, Luisa; Pfister, Laurent; Klaus, Julian

    2016-04-01

    Preferential flow plays an important role for water flow and solute transport. The inclusion of preferential flow, for example with dual porosity or dual permeability approaches, is a common feature in transport simulations at the plot scale. But at hillslope and catchment scales, incorporation of macropore and fracture flow into distributed hydrologic 3D models is rare, often due to limited data availability for model parameterisation. In this study, we incorporated preferential flow into an existing 3D integrated surface subsurface hydrologic model (HydroGeoSphere) of a headwater region (6 ha) of the forested Weierbach catchment in western Luxembourg. Our model philosophy was a strong link between measured data and the model setup. The model setup we used previously had been parameterised and validated based on various field data. But existing macropores and fractures had not been considered in this initial model setup. The multi-criteria validation revealed a good model performance but also suggested potential for further improvement by incorporating preferential flow as additional process. In order to pursue the data driven model philosophy for the implementation of preferential flow, we analysed the results of plot scale bromide sprinkling and infiltration experiments carried out in the vicinity of the Weierbach catchment. Three 1 sqm plots were sprinkled for one hour and excavated one day later for bromide depth profile sampling. We simulated these sprinkling experiments at the soil column scale, using the parameterisation of the base headwater model extended by a second permeability domain. Representing the bromide depth profiles was successful without changing this initial parameterisation. Moreover, to explain the variability between the three bromide depth profiles it was sufficient to adapt the dual permeability properties, indicating the spatial heterogeneity of preferential flow. Subsequently, we incorporated the dual permeability simulation in the

  5. Modeling preferential flow and its consequences on solute transfer in a strongly heterogeneous deposit

    Science.gov (United States)

    Ben Slimene, Erij; Lassabatere, Laurent; Winiarski, Thierry; Gourdon, Remy

    2016-04-01

    The understanding of the fate of pollutants in the vadose zone is a prerequisite to manage soil and groundwater quality. Water infiltrates into the soil and carries a large amount of pollutants (heavy metals, organic compounds, etc.). The quality of groundwater depends on the capability of soils to remove pollutants while water infiltrates. The capability of soils to remove pollutants depends not only on their geochemical properties and affinity with pollutants but also on the quality of the contact between the reactive particles of the soil and pollutants. In such a context, preferential flows are the worst scenario since they prevent pollutants from reaching large parts of the soil including reactive zones that could serve for pollutant removal. The negative effects of preferential flow have already been pointed out by several studies. In this paper, we investigate numerically the effect of the establishment of preferential flow in a numerical section (13.5m long and 2.5m deep) that mimics a strongly heterogeneous deposit. The modelled deposit is made of several lithofacies with contrasting hydraulic properties. The numerical study proves that this strong contrast in hydraulic properties triggers the establishment of preferential flow (capillary barriers and funneled flow). Preferential flow develops mainly for low initial water contents and low fluxes imposed at the soil surface. The impact of these flows on solute transfer is also investigated as a function of solute reactivity and affinity to soil sorption sites. Modeled results clearly show that solute transport is greatly impacted by flow heterogeneity. Funneled flows have the same impacts as water fractionation into mobile and immobile transfer with a fast transport of solutes by preferential flow and solute diffusion to zones where the flow is slower. Such a pattern greatly impacts retention and reduces the access of pollutants into large parts of the soil. Retention is thus greatly reduced at the section

  6. Aggregation of Dodecyl 1-Pyrenylmethyl Ether and Its Application in Structure-Polarity Relations of Aggregates

    Institute of Scientific and Technical Information of China (English)

    SANG,Da-Yong; TIAN,Juan; JI,Guo-Zhen

    2006-01-01

    The aggregation behavior of dodecyl 1-pyrenylmethyl ether was studied in dioxane-water mixture solvents by fluorescence techniques. The labeled pyrenyl group was effective in monitoring the polarity change of its environment during aggregation processes. Based on the structural effects such as chain-length effect, self-coiling effect,and branch-group effect on the polarity of the probe environment, the structure features of aggregates were discussed and have been used to interpret the effect of the structural features on the aggregates formed by three cholesteryl esters and three long chain alkanes.

  7. Pore structure of natural and regenerated soil aggregates

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Arthur, Emmanuel; de Jonge, Lis Wollesen;

    2014-01-01

    of the soil type and organic matter amendment, and was vastly different from the state of natural aggregates. Aggregate porosity (> 30 Hm) was observed to be a good predictor for the mechanical properties of aggregates. In general, natural aggregates were stronger than lysimeter aggregates.......Quantitative characterization of aggregate pore structure can reveal the evolution of aggregates under different land use and management practices and their effects on soil processes and functions. Advances in X-ray Computed Tomography (CT) provide powerful means to conduct such characterization....... This study examined aggregate pore structure of three differently managed same textured Danish soils (mixed forage cropping, MFC; mixed cash cropping, MCC; cereal cash cropping, CCC) for (i) natural aggregates, and (ii) aggregates regenerated after 20 months of incubation. In total, 27 aggregates (8-16 mm...

  8. Feedback Reduction for Random Beamforming in Multiuser MIMO Broadcast Channel

    CERN Document Server

    Li, Jin-Hao; Tsai, Yu-Lun

    2011-01-01

    For the multiuser multiple-input multiple-output (MIMO) downlink channel, the users feedback their channel state information (CSI) to help the base station (BS) schedule users and improve the system sum rate. However, this incurs a large aggregate feedback bandwidth which grows linearly with the number of users. In this paper, we propose a novel scheme to reduce the feedback load in a downlink orthogonal space division multiple access (SDMA) system with zero-forcing receivers by allowing the users to dynamically determine the number of feedback bits to use according to multiple decision thresholds. Through theoretical analysis, we show that, while keeping the aggregate feedback load of the entire system constant regardless of the number of users, the proposed scheme almost achieves the optimal asymptotic sum rate scaling with respect to the number of users (also known as the multiuser diversity). Specifically, given the number of thresholds, the proposed scheme can achieve a constant portion of the optimal su...

  9. Identification of Leishmania proteins preferentially released in infected cells using change mediated antigen technology (CMAT.

    Directory of Open Access Journals (Sweden)

    Peter E Kima

    Full Text Available Although Leishmania parasites have been shown to modulate their host cell's responses to multiple stimuli, there is limited evidence that parasite molecules are released into infected cells. In this study, we present an implementation of the change mediated antigen technology (CMAT to identify parasite molecules that are preferentially expressed in infected cells. Sera from mice immunized with cell lysates prepared from L. donovani or L. pifanoi-infected macrophages were adsorbed with lysates of axenically grown amastigotes of L. donovani or L. pifanoi, respectively, as well as uninfected macrophages. The sera were then used to screen inducible parasite expression libraries constructed with genomic DNA. Eleven clones from the L. pifanoi and the L. donovani screen were selected to evaluate the characteristics of the molecules identified by this approach. The CMAT screen identified genes whose homologs encode molecules with unknown function as well as genes that had previously been shown to be preferentially expressed in the amastigote form of the parasite. In addition a variant of Tryparedoxin peroxidase that is preferentially expressed within infected cells was identified. Antisera that were then raised to recombinant products of the clones were used to validate that the endogenous molecules are preferentially expressed in infected cells. Evaluation of the distribution of the endogenous molecules in infected cells showed that some of these molecules are secreted into parasitophorous vacuoles (PVs and that they then traffic out of PVs in vesicles with distinct morphologies. This study is a proof of concept study that the CMAT approach can be applied to identify putative Leishmania parasite effectors molecules that are preferentially expressed in infected cells. In addition we provide evidence that Leishmania molecules traffic out of the PV into the host cell cytosol and nucleus.

  10. Land cover effects on infiltration and preferential flow pathways in the high rainfall zone of Madagascar

    Science.gov (United States)

    Zwartendijk, Bob; van Meerveld, Ilja; Ravelona, Maafaka; Razakamanarivo, Herintsitohaina; Ghimire, Chandra; Bruijnzeel, Sampurno; Jones, Julia

    2015-04-01

    Shortened slash-and-burn cycles exhaust agricultural land and have resulted in extensive tracts of highly degraded land across the tropics. Land degradation typically results in decreased rainfall infiltration due to a reduced field-saturated hydraulic conductivity of the topsoil because of a progressive decline in soil organic matter, exposure to raindrop impact, surface sealing and compaction. This results, in turn, in enhanced surface runoff and erosion, and consequently less subsurface flow and groundwater recharge. On the other hand, natural vegetation regrowth or active reforestation can lead to a renewed accumulation of soil organic matter, macropore development and increased infiltration rates. As part of the P4GES project (Can Paying 4 Global Ecosystem Services values reduce poverty?; www.p4ges.org), we study the effects of land use change and reforestation on water resources in the Corridor Ankeniheny-Zahamena (CAZ) in eastern Madagascar. In this poster, we present the results of infiltration and preferential flow measurements in four different land uses in the southern part of the CAZ: (i) closed canopy forest, (ii) 3-14 year-old regrowth on fallow land (savokas), (iii) exhausted and severely degraded land (tany maty), and (iv) recently reforested sites (6-8 years old). The results show that infiltrability increases significantly after several years of forest regrowth after land abandonment, but it remains unclear whether active replanting decreases the time required for restoration of soil hydrological functioning. Preferential flow pathways differed strikingly between the respective land cover types: infiltration in mature forests was predominantly characterized by macropore flow (preferential flow pathways), whereas infiltration in exhausted agricultural land was dominated by matrix flow (few preferential flow pathways). Occurrence of preferential flow pathways in reforestation and fallow sites varied considerably. These results suggest that land

  11. Controls on matrix flow, preferential flow and deep drainage rates in an alluvial Vertisol.

    Science.gov (United States)

    Arnold, Sven; Larsen, Joshua; Reading, Lucy; Finch, Warren; Bulovic, Nevenka; McIntyre, Neil

    2016-04-01

    Deep drainage is the process that describes water percolating from the land surface to a depth below the root zone where it may contribute to groundwater recharge. Quantitative estimation of deep drainage through Vertisols is challenging, largely due to the unknown relative contributions from: (i) flow through the soil matrix; and (ii) flow along preferential pathways in particular soil cracks, and how to model the transience of the relative contributions. The Condamine River Alluvium, a significant aquifer in semi-arid eastern Australia, is mostly covered by uniform dark cracking clays such as Black and Grey Vertisols. The aim of this study was to identify the environmental conditions (rainfall, antecedent soil moisture, etc) controlling matrix and preferential flow in selected Vertisol profiles at the time scale of individual rainfall events. Field experiments (including 16 probes recording soil moisture at one hour intervals across eight depths between 100 mm and 4000 mm) provide extensive soil moisture data, supplemented by weather station data collected at 15-minute intervals. In addition, laboratory experiments were used to infer the water retention curves. These data were used to (i) derive deep drainage rates using the zero-flux plane method, and (ii) calibrate a soil moisture balance model that represents both matrix and preferential flow. The model was used to estimate the parts of the vertical water flux attributed to soil matrix and preferential flow. High antecedent soil moisture was associated with low fluxes at shallow depths, however at deeper depths both low and high antecedent soil moisture were associated with larger fluxes. Further, both rainfall amount and intensity controlled the interplay between matrix and preferential flow. The results reveal new insights into deep drainage processes in Vertisols and provide the basis for developing a practical approach for deep drainage estimation.

  12. Aggregates reduce transport distance of soil organic carbon: are our balances correct?

    Directory of Open Access Journals (Sweden)

    Y. Hu

    2014-06-01

    Full Text Available The effect of soil erosion on global carbon cycling, especially as a source or sink for greenhouse gases, has been the subject of intense debate. The controversy arises mostly from the lack of information on the fate of eroded soil organic carbon (SOC whilst in-transit from the site of erosion to the site of longer-term deposition. Solving this controversy requires an improved understanding of the transport distance of eroded SOC, which is principally related to the settling velocity of sediment fractions that carry the eroded SOC. Although settling velocity has already been included in some erosion models, it is often based on mineral particle size distribution. For aggregated soils, settling velocities are affected by their actual aggregate size rather than by mineral particle size distribution. Aggregate stability is, in turn, strongly influenced by SOC. In order to identify the effect of aggregation of source soil on the transport distance of eroded SOC, and its susceptibility to mineralization after transport and temporary deposition, a rainfall simulation was carried out on a silty loam. Both the eroded sediments and undisturbed soil were fractionated into six different size classes using a settling tube apparatus according to their settling velocities. Weight, SOC concentration and instantaneous respiration rates were measured for each of the six class fractions. Our results indicate that: (1 41% of the eroded SOC was transported with coarse aggregates that would be likely re-deposited down eroding hillslopes, rather than with fine particles likely transferred to water courses; (2 erosion was prone to accelerate the mineralization of eroded SOC, and thus might contribute more CO2 to the atmosphere than current estimates which often ignore potential effects of aggregation; (3 preferential deposition of SOC-rich coarse aggregates potentially causes an increase of SOC remaining in the colluvial system and a reduction of SOC flux to the

  13. A linearization of quantum channels

    Science.gov (United States)

    Crowder, Tanner

    2015-06-01

    Because the quantum channels form a compact, convex set, we can express any quantum channel as a convex combination of extremal channels. We give a Euclidean representation for the channels whose inverses are also valid channels; these are a subset of the extreme points. They form a compact, connected Lie group, and we calculate its Lie algebra. Lastly, we calculate a maximal torus for the group and provide a constructive approach to decomposing any invertible channel into a product of elementary channels.

  14. Towards a consumer sentiment channel of monetary policy

    OpenAIRE

    Debes, Sebastian; Gareis, Johannes; Mayer, Eric; Rüth, Sebastian

    2014-01-01

    We investigate the role of consumer confidence in the transmission of monetary policy shocks from an empirical and theoretical perspective. Standard VAR based analysis suggests that an empirical measure of consumer confidence drops significantly after a monetary tightening and amplifies the impact of monetary policy on aggregate consumption. Using a behavioral DSGE model, we show that a consumer sentiment channel can account for the empirical findings. In an environment of heterogeneous expec...

  15. Broadband Wireless Channel measurements for high speed trains

    OpenAIRE

    Kaltenberger, Florian; BYIRINGIRO, Auguste; Arvanitakis, George; GHADDAB, Ryad; NUSSBAUM, Dominique; Knopp, Raymond; Berbineau, Marion; Cocheril, Yann; Philippe, Henri

    2014-01-01

    We describe a channel sounding measurement campaign for cellular broadband wireless communications with high speed trains that was carried out in the context of the project CORRIDOR. The campaign combines MIMO and carrier aggregation to achieve very highth roughputs. We compare two different scenarios, the first one reflects a cellular deployment, where the base station is about 1 km away from the railway line. The second scenario corresponds to a railway deployed network, where the base stat...

  16. 鹫峰国家森林公园不同林分下土壤优先流现象研究%Soil Preferential Flow under Different Forest Stands in Jiufeng National Forestry Park

    Institute of Scientific and Technical Information of China (English)

    肖自幸; 朱蔚利; 牛健植; 邵文伟; 张由松

    2011-01-01

    优先流是土壤中普遍存在的一种水分和溶质运移现象,为初步了解土石山区植被下的土壤水分运动,用亮蓝野外染色示踪试验研究了位于北京西北部的鹫峰国家森林公园不同林分下土壤中的优先流.从染色结果来看:在3种不同林分下的土壤中均存在较明显的优先流现象,且不同林分下土壤优先流的表现形式不同.染色面积的百分比显示了示踪剂在剖面上的分布,反映出部分水分通过优先流直接进入到土壤下层.优先流的存在对土石山区降雨条件下的水文过程产生重要影响.%Preferential flow is a common phenomenon of water and solute transport in soil. In order to understand the water movement under vegetation in rocky mountain area, the soil preferential flow under different forest stands in Jiufeng National Forestry Park in northwest Beijing was researched by using brilliant blue dye tracer method. The results showed that the preferential flow exists in the three different forest stands and the expression forms were different under different forest stands. The percentage of dyed area showed the tracer distribution in the profile, and it reflected some water reach the bottom of soil through the preferential flow channels. The presence of preferential flow has an important impact on the hydrological processes under rainfall conditions in earth-rocky mountainous area. .

  17. RFI channels, 2

    Science.gov (United States)

    Mceliece, R. J.

    1981-01-01

    The cutoff parameters for a class of channel models exhibiting burst noise behavior were calculated and the performance of interleaved coding strategies was evaluated. It is concluded that, provided the channel memory is large enough and is properly exploited, interleaved coding is nearly optimal.

  18. A Novel Method to Quantify Soil Aggregate Stability by Measuring Aggregate Bond Energies

    Science.gov (United States)

    Efrat, Rachel; Rawlins, Barry G.; Quinton, John N.; Watts, Chris W.; Whitmore, Andy P.

    2016-04-01

    Soil aggregate stability is a key indicator of soil quality because it controls physical, biological and chemical functions important in cultivated soils. Micro-aggregates are responsible for the long term sequestration of carbon in soil, therefore determine soils role in the carbon cycle. It is thus vital that techniques to measure aggregate stability are accurate, consistent and reliable, in order to appropriately manage and monitor soil quality, and to develop our understanding and estimates of soil as a carbon store to appropriately incorporate in carbon cycle models. Practices used to assess the stability of aggregates vary in sample preparation, operational technique and unit of results. They use proxies and lack quantification. Conflicting results are therefore drawn between projects that do not provide methodological or resultant comparability. Typical modern stability tests suspend aggregates in water and monitor fragmentation upon exposure to an un-quantified amount of ultrasonic energy, utilising a laser granulometer to measure the change in mean weight diameter. In this project a novel approach has been developed based on that of Zhu et al., (2009), to accurately quantify the stability of aggregates by specifically measuring their bond energies. The bond energies are measured operating a combination of calorimetry and a high powered ultrasonic probe, with computable output function. Temperature change during sonication is monitored by an array of probes which enables calculation of the energy spent heating the system (Ph). Our novel technique suspends aggregates in heavy liquid lithium heteropolytungstate, as opposed to water, to avoid exposing aggregates to an immeasurable disruptive energy source, due to cavitation, collisions and clay swelling. Mean weight diameter is measured by a laser granulometer to monitor aggregate breakdown after successive periods of calculated ultrasonic energy input (Pi), until complete dispersion is achieved and bond

  19. Athermalized channeled spectropolarimeter enhancement.

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Julia Craven; Way, Brandyn Michael; Mercier, Jeffrey Alan; Hunt, Jeffery P.

    2013-09-01

    Channeled spectropolarimetry can measure the complete polarization state of light as a function of wavelength. Typically, a channeled spectropolarimeter uses high order retarders made of uniaxial crystal to amplitude modulate the measured spectrum with the spectrally-dependent Stokes polarization information. A primary limitation of conventional channeled spectropolarimeters is related to the thermal variability of the retarders. Thermal variation often forces frequent system recalibration, particularly for field deployed systems. However, implementing thermally stable retarders, made of biaxial crystal, results in an athermal channeled spectropolarimeter that relieves the need for frequent recalibration. This report presents experimental results for an anthermalized channeled spectropolarimeter prototype produced using potassium titanyl phosphate. The results of this prototype are compared to the current thermal stabilization state of the art. Finally, the application of the technique to the thermal infrared is studied, and the athermalization concept is applied to an infrared imaging spectropolarimeter design.

  20. Channelling versus inversion

    DEFF Research Database (Denmark)

    Gale, A.S.; Surlyk, Finn; Anderskouv, Kresten

    2013-01-01

    . Within this channel were smaller erosional structures (<10 m deep) that truncate originally horizontal bedding, are floored by hardgrounds, and locally have a basal fill of granular phosphorite. The entire channel system was progressively infilled by chalk, as demonstrated by the expanded succession of...... the lower Campanian Culver Chalk Formation. The beds of the channel fill are cut by small step faults, resulting from gravitational collapse. Complete burial had taken place by the base of the upper Campanian Portsdown Chalk Formation, which is of even thickness across the region. The structures are......Evidence from regional stratigraphical patterns in Santonian−Campanian chalk is used to infer the presence of a very broad channel system (5 km across) with a depth of at least 50 m, running NNW−SSE across the eastern Isle of Wight; only the western part of the channel wall and fill is exposed...

  1. Preferential flow in connected soil structures and the principle of "maximum energy dissipation": A thermodynamic perspective

    Science.gov (United States)

    Zehe, E.; Blume, T.; Bloeschl, G.

    2009-04-01

    "There is preferential flow at all scales"? This was a key message in a talk on ?Idle thoughts on a unifying theory of catchment hydrology? given by Bloeschl (2006). In this context ?preferential flow? was used to address rapid water flow along spatially connected flow paths of minimum flow resistance. Preferential flow seems in fact rather the rule than the exception. It occurs locally in non capillary macropores, at the hillslope scale in surface rills or through subsurface pipes. Rapid flow in connected biopores or sometimes shrinkage cracks is today accepted to play a key role for transport of agrochemicals in cohesive soils. The spatial distribution of worm burrows in the landscape may, furthermore, exert crucial control on rainfall runoff response and sediment yields at the hillslope and catchment scales. However, even if the population of connected biopores/macropores is known in soil we struggle in predicting onset, timing and strength of preferential flow events. Preferential flow is an intermittent, threshold phenomenon. Onset and intensity seems to be determined by the strength of the rainfall forcing and the wetness state of the soil. Furthermore, burrows of deep digging aenecic earthworms can ? even when being abandoned ? persist over decades as suggested by accumulation of clay particles or even radio nuclides. Thus, these structures ?survive? severe rainfall and subsurface flow events and still remain functional in the hydrological system. Why is it sometimes ?favourable? to take flow paths of minimum flow resistance and sometimes not? Why do these flow paths/ structures persist such a long time? Following Kleidon and Schimansky (2008) we suggest that a thermodynamic perspective ? looking at soil water flow as dissipative process in an open, non equilibrium thermodynamic system ? may help unrevealing these questions. However, we suggest a complementary perspective on soil water flow focusing rather on entropy production but on dissipation of

  2. Spatial Prediction of Soil Aggregate Stability and Aggregate-Associated Organic Carbon Content at the Catchment Scale Using Geostatistical Techniques

    Institute of Scientific and Technical Information of China (English)

    J.MOHAMMADI; M.H.MOTAGHIAN

    2011-01-01

    The association of organic carbon with secondary parzicles (aggregates) results in its storage and retention in soil. A study was carried out at a catchment covering about 92 km2 to predict spatial variability of soil water-stable aggregates (WSA), mean weight diameter (MWD) of aggregates and organic carbon (OC) content in macro- (> 2 mm), meso- (1-2 mm), and micro-aggregate (< 1 mm) fractions, using geostatistical methods. One hundred and eleven soil samples were c(o)llected at the 0-10 cm depth and fractionated into macro-, meso-, and micro-aggregates by wet sieving. The OC content was determined for each fraction. A greater percentage of water-stable aggregates was found for micro-aggregates, followed by meso-aggregates. Aggregate OC content was greatest in meso-aggregates (9 g kg-1), followed by micro-aggregates (7 g kg-1), while the least OC content was found in macro-aggregates (3 g kg-1). Although a significart effect (P = 0.000) of aggregate size on aggregate OC content was found, however, our findings did not support the model of aggregate hierarchy.Land use had a significant effect (P = 0.073) on aggregate OC content. The coefficients of variation (CVs) for OC contents associated with each aggregate fraction indicated macro-aggregates as the most variable (CV = 71%). Among the aggregate fractions, the micro-aggregate fraction had a lower CV value of 27%. The mean content of WSA ranged from 15% for macro-aggregates to 84% for micro-aggregates. Geostatistical analysis showed that the measured soil variables exhibited differences in their spatial patterns in both magnitude and space at each aggregate size fraction. The relative nugget variance for most aggregate-associated properties was lower than 45%. The range value for the variogram of water-stable aggregates was almost similar (about 3 km) for the three studied aggregate size classes. The range value for the variogram of aggregate-associated OC contents ranged from about 3 km for macro-aggregates

  3. Metaconcrete: Engineered aggregates for enhanced dynamic performance

    Science.gov (United States)

    Mitchell, Stephanie J.

    This work presents the development and investigation of a new type of concrete for the attenuation of waves induced by dynamic excitation. Recent progress in the field of metamaterials science has led to a range of novel composites which display unusual properties when interacting with electromagnetic, acoustic, and elastic waves. A new structural metamaterial with enhanced properties for dynamic loading applications is presented, which is named metaconcrete. In this new composite material the standard stone and gravel aggregates of regular concrete are replaced with spherical engineered inclusions. Each metaconcrete aggregate has a layered structure, consisting of a heavy core and a thin compliant outer coating. This structure allows for resonance at or near the eigenfrequencies of the inclusions, and the aggregates can be tuned so that resonant oscillations will be activated by particular frequencies of an applied dynamic loading. The activation of resonance within the aggregates causes the overall system to exhibit negative effective mass, which leads to attenuation of the applied wave motion. To investigate the behavior of metaconcrete slabs under a variety of different loading conditions a finite element slab model containing a periodic array of aggregates is utilized. The frequency dependent nature of metaconcrete is investigated by considering the transmission of wave energy through a slab, which indicates the presence of large attenuation bands near the resonant frequencies of the aggregates. Applying a blast wave loading to both an elastic slab and a slab model that incorporates the fracture characteristics of the mortar matrix reveals that a significant portion of the supplied energy can be absorbed by aggregates which are activated by the chosen blast wave profile. The transfer of energy from the mortar matrix to the metaconcrete aggregates leads to a significant reduction in the maximum longitudinal stress, greatly improving the ability of the material

  4. Aggregate Particles in the Plumes of Enceladus

    CERN Document Server

    Gao, Peter; Zhang, Xi; Ingersoll, Andrew P

    2015-01-01

    Estimates of the total particulate mass of the plumes of Enceladus are important to constrain theories of particle formation and transport at the surface and interior of the satellite. We revisit the calculations of Ingersoll and Ewald (2011), who estimated the particulate mass of the Enceladus plumes from strongly forward scattered light in Cassini ISS images. We model the plume as a combination of spherical particles and irregular aggregates resulting from the coagulation of spherical monomers, the latter of which allows for plumes of lower particulate mass. Though a continuum of solutions are permitted by the model, the best fits to the ISS data consist either of low mass plumes composed entirely of small aggregates or high mass plumes composed of large aggregates and spheres. The high mass plumes can be divided into a population of large aggregates with total particulate mass of 116 +/- 12 X 10^3 kg, and a mixed population of spheres and aggregates consisting of a few large monomers that has a total plume...

  5. Soil aggregation under different management systems

    Directory of Open Access Journals (Sweden)

    Cibele Mascioli Rebello Portella

    2012-12-01

    Full Text Available Considering that the soil aggregation reflects the interaction of chemical, physical and biological soil factors, the aim of this study was evaluate alterations in aggregation, in an Oxisol under no-tillage (NT and conventional tillage (CT, since over 20 years, using as reference a native forest soil in natural state. After analysis of the soil profile (cultural profile in areas under forest management, samples were collected from the layers 0-5, 5-10, 10-20 and 20-40 cm, with six repetitions. These samples were analyzed for the aggregate stability index (ASI, mean weighted diameter (MWD, mean geometric diameter (MGD in the classes > 8, 8-4, 4-2, 2-1, 1-0.5, 0.5-0.25, and < 0.25 mm, and for physical properties (soil texture, water dispersible clay (WDC, flocculation index (FI and bulk density (Bd and chemical properties (total organic carbon - COT, total nitrogen - N, exchangeable calcium - Ca2+, and pH. The results indicated that more intense soil preparation (M < NT < PC resulted in a decrease in soil stability, confirmed by all stability indicators analyzed: MWD, MGD, ASI, aggregate class distribution, WDC and FI, indicating the validity of these indicators in aggregation analyses of the studied soil.

  6. Static compression of porous dust aggregates

    Science.gov (United States)

    Kataoka, Akimasa; Tanaka, Hidekazu; Okuzumi, Satoshi; Wada, Koji

    2013-07-01

    To understand the structure evolution of dust aggregates is a key in the planetesimal formation. Dust grains become fluffy by coagulation in protoplanetary disks. However, once they become fluffy, they are not sufficiently compressed by collisional compression to form compact planetesimals (Okuzumi et al. 2012, ApJ, 752, 106). Thus, some other compression mechanisms are required to form planetesimals. We investigate the static compression of highly porous aggregates. First, we derive the compressive strength by numerical N-body simulations (Kataoka et al. 2013, A&A, 554, 4). Then, we apply the strength to protoplanetary disks, supposing that the highly porous aggregates can be quiasi-statically compressed by ram pressure of the disk gas and the self gravity. As a result, we find the pathway of the dust structure evolution from dust grains via fluffy aggregates to compact planetesimals. Moreover, we find that the fluffy aggregates overcome the barriers in planetesimal formation, which are radial drift, fragmentation, and bouncing barriers. (The paper is now available on arXiv: http://arxiv.org/abs/1307.7984 )

  7. Oil-Price Shocks: Beyond Standard Aggregate Demand/Aggregate Supply Analysis.

    Science.gov (United States)

    Elwood, S. Kirk

    2001-01-01

    Explores the problems of portraying oil-price shocks using the aggregate demand/aggregate supply model. Presents a simple modification of the model that differentiates between production and absorption of goods, which enables it to better reflect the effects of oil-price shocks on open economies. (RLH)

  8. Metastable Fractal Aggregates as a Result of Competition Between Diffusion-Limited Aggregation and Dissociation

    CERN Document Server

    Gordienko, Yuriy G

    2015-01-01

    The cellular automaton model is used to simulate diffusion and aggregation with dissociation of point particles in 2D. A continuous phase transition is found that separates creation of compact aggregates and fractal ones. The transition is the function of pair-interaction energy ($E_b$), type of neighborhood and temperature $T$. Manifestations of the transition in real physical systems are discussed.

  9. SENSOR indicator framework, and methods for aggregation/dis-aggregation - a guideline

    DEFF Research Database (Denmark)

    Frederiksen, P.; Kristensen, P.; Briquel, V.;

    This report collects three guideline contributions to Sensor: the development and proposal of an indicator framework for sustainability impact assessment and criteria for indicator selection, an assessment of international indicator sets for identification of potential indicators for SENSOR impac...... issues, and a description of problems and methodologies for aggregation and dis-aggregation of data and indicators....

  10. Web Data Aggregation in MOLAP: Approach, Language, and Implementation

    Institute of Scientific and Technical Information of China (English)

    ZHU Yan; TANG Hui-jia; MA Yong-qiang

    2007-01-01

    This paper investigates the Web data aggregation issues in multidimensional on-line analytical processing (MOLAP) and presents a rule-driven aggregation approach. The core of the approach is defining aggregate rules. To define the rules for reading warehouse data and computing aggregates, a rule definition language - array aggregation language (AAL) is developed. This language treats an array as a function from indexes to values and provides syntax and semantics based on monads. External functions can be called in aggregation rules to specify array reading, writing, and aggregating. Based on the features of AAL, array operations are unified as function operations, which can be easily expressed and automatically evaluated. To implement the aggregation approach, a processor for computing aggregates over the base cube and for materializing them in the data warehouse is built, and the component structure and working principle of the aggregation processor are introduced.

  11. THE DISTRIBUTION OF PREFERENTIAL PATHS AND ITS RELATION TO THE SOIL CHARACTERISTICS IN THE THREE GORGES AREA, CHINA

    Institute of Scientific and Technical Information of China (English)

    Hongjiang ZHANG; Jinhua CHENG; Yuhu SHI; Yun CHENG

    2007-01-01

    To study the characteristics of the distribution of the preferential paths and the affecting factors in the Three Gorges area, four soil profiles were dug to observe the distribution of preferential paths in the Quxi watershed in the Yangtze River basin. The Morisita exponential test method was used to examine the distribution type of preferential paths. The physical properties and infiltration characteristics of the soil were also measured to evaluate their relationship to preferential paths. The results showed that in this area, preferential paths clustered and mainly distributed in the 80-100 cm soil layer, and along the interface between the weathered layer and semi-weathered layer. There were more non-capillary pores in the 83-110 cm layer than in the other layers. It can be derived that most non-capillary pores in this layer were preferential paths caused by geological processes and rotten plant roots. The percentage of coarse soil particles increased with the depth of the soil layer. In the deeper soil layer, the coarse soil particles helped the formation of preferential paths. The fastest steady infiltration rate was observed in the of 83-110cm layer, which is inferred to be due to the greater number of preferential paths.

  12. Origin of preferential flow and its controlling factors on emission potential using numerical simulations and lab experiments

    NARCIS (Netherlands)

    Baviskar, S.M.; Heimovaara, T.J.

    2015-01-01

    We believe the unsaturated and heterogeneous nature of landfills leads to the emergence of preferential pathways of water and dissolved compounds through the waste body. In this research we explore the origin of preferential flow in a porous media with a deterministic numerical model. In this model

  13. Arginine-aromatic interactions and their effects on arginine-induced solubilization of aromatic solutes and suppression of protein aggregation

    KAUST Repository

    Shah, Dhawal

    2011-09-21

    We examine the interaction of aromatic residues of proteins with arginine, an additive commonly used to suppress protein aggregation, using experiments and molecular dynamics simulations. An aromatic-rich peptide, FFYTP (a segment of insulin), and lysozyme and insulin are used as model systems. Mass spectrometry shows that arginine increases the solubility of FFYTP by binding to the peptide, with the simulations revealing the predominant association of arginine to be with the aromatic residues. The calculations further show a positive preferential interaction coefficient, Γ XP, contrary to conventional thinking that positive Γ XP\\'s indicate aggregation rather than suppression of aggregation. Simulations with lysozyme and insulin also show arginine\\'s preference for aromatic residues, in addition to acidic residues. We use these observations and earlier results reported by us and others to discuss the possible implications of arginine\\'s interactions with aromatic residues on the solubilization of aromatic moieties and proteins. Our results also highlight the fact that explanations based purely on Γ XP, which measures average affinity of an additive to a protein, could obscure or misinterpret the underlying molecular mechanisms behind additive-induced suppression of protein aggregation. © 2011 American Institute of Chemical Engineers (AIChE).

  14. Morphology-Specific Inhibition of β-Amyloid Aggregates by 17β-Hydroxysteroid Dehydrogenase Type 10.

    Science.gov (United States)

    Aitken, Laura; Quinn, Steven D; Perez-Gonzalez, Cibran; Samuel, Ifor D W; Penedo, J Carlos; Gunn-Moore, Frank J

    2016-06-01

    A major hallmark of Alzheimer's disease (AD) is the formation of toxic aggregates of the β-amyloid peptide (Aβ). Given that Aβ peptides are known to localise within mitochondria and interact with 17β-HSD10, a mitochondrial protein expressed at high levels in AD brains, we investigated the inhibitory potential of 17β-HSD10 against Aβ aggregation under a range of physiological conditions. Fluorescence self-quenching (FSQ) of Aβ(1-42) labelled with HiLyte Fluor 555 was used to evaluate the inhibitory effect under conditions established to grow distinct Aβ morphologies. 17β-HSD10 preferentially inhibits the formation of globular and fibrillar-like structures but has no effect on the growth of amorphous plaque-like aggregates at endosomal pH 6. This work provides insights into the dependence of the Aβ-17β-HSD10 interaction with the morphology of Aβ aggregates and how this impacts enzymatic function. PMID:26991863

  15. Wind energy aggregation: A coalitional game approach

    KAUST Repository

    Baeyens, E.

    2011-12-01

    In this paper we explore the extent to which a group of N wind power producers can exploit the statistical benefits of aggregation and quantity risk sharing by forming a willing coalition to pool their variable power to jointly offer their aggregate power output as single entity into a forward energy market. We prove that wind power generators will always improve their expected profit when they aggregate their generated power and use tools from coalitional game theory to design fair sharing mechanisms to allocate the payoff among the coalition participants. We show that the corresponding coalitional game is super-additive and has a nonempty core. Hence, there always exists a mechanism for profit-sharing that makes the coalition stable. However, the game is not convex and the celebrated Shapley value may not belong to the core of the game. An allocation mechanism that minimizes the worst-case dissatisfaction is proposed. © 2011 IEEE.

  16. Aggregation of Calcium Silicate Hydrate Nanoplatelets.

    Science.gov (United States)

    Delhorme, Maxime; Labbez, Christophe; Turesson, Martin; Lesniewska, Eric; Woodward, Cliff E; Jönsson, Bo

    2016-03-01

    We study the aggregation of calcium silicate hydrate nanoplatelets on a surface by means of Monte Carlo and molecular dynamics simulations at thermodynamic equilibrium. Calcium silicate hydrate (C-S-H) is the main component formed in cement and is responsible for the strength of the material. The hydrate is formed in early cement paste and grows to form platelets on the nanoscale, which aggregate either on dissolving cement particles or on auxiliary particles. The general result is that the experimentally observed variations in these dynamic processes generically called growth can be rationalized from interaction free energies, that is, from pure thermodynamic arguments. We further show that the surface charge density of the particles determines the aggregate structures formed by C-S-H and thus their growth modes. PMID:26859614

  17. Internal Aggregation Models on the Comb Lattice

    CERN Document Server

    Huss, Wilfried

    2011-01-01

    The comb C is a natural spanning tree of the Euclidean lattice Z^2. We study three related cluster growth models on C: internal diffusion limited aggregation (IDLA), in which random walkers move on the vertices of C until reaching an unoccupied site where they stop; rotor-router aggregation in which particles perform deterministic walks, and stop when reaching a site previously unoccupied; and the divisible sandpile model where at each vertex there is a pile of sand, for which, at each step, the mass exceeding 1 is distributed equally among the neighbours. We describe the shape of the divisible sandpile cluster on C, which is then used to give inner bounds for IDLA and rotor-router aggregation.

  18. Mechanical Properties of Autoclaved Shell-aggregate

    Institute of Scientific and Technical Information of China (English)

    MA Hailong; CUI Chong; LI Xing; Pierre Chevrier; Vanessa Bouchart; TANG Feng

    2011-01-01

    Waste solid propylene oxide sludge(POS)and fly ash were used as main raw material to prepare propylene oxide sludge aggregate(POSA)under the condition of autoclaved(180 ℃,1.0 MPa)curing.Three different test methods namely cylinder compressive strength(CCS),individual aggregate compressive strength(IACS)and strength contribution rate(SCR)proposed were used to characterize the mechanical properties of the autoclaved POSA.POS shell-aggregate with SCR of 94% were prepared under the hydrothermal synthesis and autoclaved curing.The experimental results indicate that CCS and IACS have good consistency in characterizing mechanical properties of POSA.It is suggested that SCR not only can characterize the strength of POSA core,but also can reflect the effect of shell on the performance of POSA.By means of least square method,relationships between CCS and IACS,CCS and SCR,IACS and SCR were deduced.

  19. Influence of polysaccharides on wine protein aggregation.

    Science.gov (United States)

    Jaeckels, Nadine; Meier, Miriam; Dietrich, Helmut; Will, Frank; Decker, Heinz; Fronk, Petra

    2016-06-01

    Polysaccharides are the major high-molecular weight components of wines. In contrast, proteins occur only in small amounts in wine, but contribute to haze formation. The detailed mechanism of aggregation of these proteins, especially in combination with other wine components, remains unclear. This study demonstrates the different aggregation behavior between a buffer and a model wine system by dynamic light scattering. Arabinogalactan-protein, for example, shows an increased aggregation in the model wine system, while in the buffer system a reducing effect is observed. Thus, we could show the importance to examine the behavior of wine additives under conditions close to reality, instead of simpler buffer systems. Additional experiments on melting points of wine proteins reveal that only some isoforms of thaumatin-like proteins and chitinases are involved in haze formation. We can confirm interactions between polysaccharides and proteins, but none of these polysaccharides is able to prevent haze in wine.

  20. Multi-Dimensional Aggregation for Temporal Data

    DEFF Research Database (Denmark)

    Böhlen, M. H.; Gamper, J.; Jensen, Christian Søndergaard

    2006-01-01

    Business Intelligence solutions, encompassing technologies such as multi-dimensional data modeling and aggregate query processing, are being applied increasingly to non-traditional data. This paper extends multi-dimensional aggregation to apply to data with associated interval values that capture...... when the data hold. In temporal databases, intervals typically capture the states of reality that the data apply to, or capture when the data are, or were, part of the current database state. This paper proposes a new aggregation operator that addresses several challenges posed by interval data. First......, the intervals to be associated with the result tuples may not be known in advance, but depend on the actual data. Such unknown intervals are accommodated by allowing result groups that are specified only partially. Second, the operator contends with the case where an interval associated with data expresses...

  1. Bed bug aggregation pheromone finally identified.

    Science.gov (United States)

    Gries, Regine; Britton, Robert; Holmes, Michael; Zhai, Huimin; Draper, Jason; Gries, Gerhard

    2015-01-19

    Bed bugs have become a global epidemic and current detection tools are poorly suited for routine surveillance. Despite intense research on bed bug aggregation behavior and the aggregation pheromone, which could be used as a chemical lure, the complete composition of this pheromone has thus far proven elusive. Here, we report that the bed bug aggregation pheromone comprises five volatile components (dimethyl disulfide, dimethyl trisulfide, (E)-2-hexenal, (E)-2-octenal, 2-hexanone), which attract bed bugs to safe shelters, and one less-volatile component (histamine), which causes their arrestment upon contact. In infested premises, a blend of all six components is highly effective at luring bed bugs into traps. The trapping of juvenile and adult bed bugs, with or without recent blood meals, provides strong evidence that this unique pheromone bait could become an effective and inexpensive tool for bed bug detection and potentially their control. PMID:25529634

  2. Aggregation kinetics and structure of cryoimmunoglobulins clusters

    CERN Document Server

    De Spirito, M; Bassi, F A; Di Stasio, E; Giardina, B; Arcovito, G

    2002-01-01

    Cryoimmunoglobulins are pathological antibodies characterized by a temperature-dependent reversible insolubility. Rheumatoid factors (RF) are immunoglobulins possessing anti-immunoglobulin activity and usually consist of an IgM antibody that recognizes IgG as antigen. These proteins are present in sera of patients affected by a large variety of different pathologies, such as HCV infection, neoplastic and autoimmune diseases. Aggregation and precipitation of cryoimmunoglobulins, leading to vasculiti, are physical phenomena behind such pathologies. A deep knowledge of the physico-chemical mechanisms regulating such phenomena plays a fundamental role in biological and clinical applications. In this work, a preliminary investigation of the aggregation kinetics and of the final macro- molecular structure of the aggregates is presented. Through static light scattering techniques, the gyration radius R/sub g/ and the fractal dimension D/sub m/ of the growing clusters have been determined. However, while the initial ...

  3. Effects of Titanium Dioxide Nanoparticle Aggregate Size on Gene Expression

    OpenAIRE

    Junko Okuda-Shimazaki; Saiko Takaku; Koki Kanehira; Shuji Sonezaki; Akiyohshi Taniguchi

    2010-01-01

    Titanium dioxide (titania) nanoparticle aggregation is an important factor in understanding cytotoxicity. However, the effect of the aggregate size of nanoparticles on cells is unclear. We prepared two sizes of titania aggregate particles and investigated their biological activity by analyzing biomarker expression based on mRNA expression analysis. The aggregate particle sizes of small and large aggregated titania were 166 nm (PDI = 0.291) and 596 nm (PDI = 0.417), respectively. These two siz...

  4. Effects of Particle Shape on Mechanical Properties of Aggregates

    OpenAIRE

    Benediktsson, Stefán

    2015-01-01

    Aggregates are one of the primary building material used in the world. The durability of construction aggregates will therefore depend upon the quality of aggregate mechanical properties. It is therefore important to understand how particle shape will effect mechanical properties of aggregates, measured by the Los Angeles and micro-Deval values. In order to assess the influence of particle shape on aggregate mechanical properties, the proportion of flaky and cubic particles, measured by the f...

  5. Environmental Sustainability by Use of Recycled Aggregates - An Overview

    OpenAIRE

    D. K. Gandhi; A. A. Gudadhe

    2014-01-01

    Optimum utilization of available natural resources is the major component to achieve the environmental sustainability. Development in urban infrastructure demands for large quantity of aggregates for construction. Infrastructural waste in the form of demolished aggregates is one of the major components of solid waste. By efficient use of these demolished aggregates in the form of recycled aggregates along with fresh aggregates can achieve a better solid waste management and al...

  6. Weak glycolipid binding of a microdomain-tracer peptide correlates with aggregation and slow diffusion on cell membranes.

    Directory of Open Access Journals (Sweden)

    Tim Lauterbach

    Full Text Available Organized assembly or aggregation of sphingolipid-binding ligands, such as certain toxins and pathogens, has been suggested to increase binding affinity of the ligand to the cell membrane and cause membrane reorganization or distortion. Here we show that the diffusion behavior of the fluorescently tagged sphingolipid-interacting peptide probe SBD (Sphingolipid Binding Domain is altered by modifications in the construction of the peptide sequence that both result in a reduction in binding to ganglioside-containing supported lipid membranes, and at the same time increase aggregation on the cell plasma membrane, but that do not change relative amounts of secondary structural features. We tested the effects of modifying the overall charge and construction of the SBD probe on its binding and diffusion behavior, by Surface Plasmon Resonance (SPR; Biacore analysis on lipid surfaces, and by Fluorescence Correlation Spectroscopy (FCS on live cells, respectively. SBD binds preferentially to membranes containing the highly sialylated gangliosides GT1b and GD1a. However, simple charge interactions of the peptide with the negative ganglioside do not appear to be a critical determinant of binding. Rather, an aggregation-suppressing amino acid composition and linker between the fluorophore and the peptide are required for optimum binding of the SBD to ganglioside-containing supported lipid bilayer surfaces, as well as for interaction with the membrane. Interestingly, the strength of interactions with ganglioside-containing artificial membranes is mirrored in the diffusion behavior by FCS on cell membranes, with stronger binders displaying similar characteristic diffusion profiles. Our findings indicate that for aggregation-prone peptides, aggregation occurs upon contact with the cell membrane, and rather than giving a stronger interaction with the membrane, aggregation is accompanied by weaker binding and complex diffusion profiles indicative of heterogeneous

  7. Characterization of preferential orientation of martensitic variants in a single crystal of NiMnGa

    Science.gov (United States)

    Liu, Guodong; Chen, Jinglan; Cui, Yuting; Liu, Zhuhong; Zhang, Ming; Wu, Guangheng; Brück, E.; de Boer, F. R.; Meng, Fanbin; Li, Yangxian; Qu, Jingping

    2004-06-01

    We report the detailed observation of martensitic variants in NiMnGa single crystals. The variants that are twinned with each other in different ways can be clearly identified in our single crystals by optical observation. We also investigated the preferential orientation of the martensitic variants in NiMnGa single crystals. We observed the motion of the variant boundary in response to application of a magnetic field. This observation can be used to explain phenomenologically the magnetic-field-induced strain. In the single crystal with composition Ni 52Mn 24Ga 24, martensite with seven modulated layers (7M) shows preferentially oriented variants. A completely recoverable two-way shape-memory behavior was also observed by measuring the free sample in three different directions during a complete temperature cycle. It was found that the largest strains in the [001] and [010] directions occur in different temperature ranges.

  8. New derivatives of vitamin B12 show preferential targeting of tumors.

    Science.gov (United States)

    Waibel, Robert; Treichler, Hansjörg; Schaefer, Niklaus G; van Staveren, Dave R; Mundwiler, Stefan; Kunze, Susanne; Küenzi, Martin; Alberto, Roger; Nüesch, Jakob; Knuth, Alexander; Moch, Holger; Schibli, Roger; Schubiger, Pius August

    2008-04-15

    Rapidly growing cells show an increased demand for nutrients and vitamins. The objective of our work is to exploit the supply route of vitamin B12 to deliver new derivatives of this vital vitamin to hyperproliferative cells. To date, radiolabeled ((57)Co and (111)In) vitamin B12 derivatives showed labeling of tumor tissue but also undesired high accumulation of radioactivity in normal tissue. By abolishing the interaction of a tailored vitamin B12 derivative to its transport protein transcobalamin II and therefore interrupting transcobalamin II receptor and megalin mediated uptake in normal tissue, preferential accumulation of a radiolabeled vitamin in cancer tissue could be accomplished. We identified transcobalamin I on tumors as a possible new receptor for this preferential accumulation of vitamin-mediated targeting. The low systemic distribution of radioactivity and the high tumor to blood ratio opens the possibility of a more successful clinical application of vitamin B12 for imaging or therapy.

  9. Assortativity and leadership emergence from anti-preferential attachment in heterogeneous networks

    CERN Document Server

    Sendiña-Nadal, I; Wang, Z; Havlin, S; Boccaletti, S

    2015-01-01

    Many real-world networks exhibit degree-assortativity, with nodes of similar degree more likely to link to one another. Particularly in social networks, the contribution to the total assortativity varies with degree, featuring a distinctive peak slightly past the average degree. The way traditional models imprint assortativity on top of pre-defined topologies is via degree-preserving link permutations, which however destroy the particular graph's hierarchical traits of clustering. Here, we propose the first generative model which creates heterogeneous networks with scale-free-like properties and tunable realistic assortativity. In our approach, two distinct populations of nodes are added to an initial network seed: one (the followers) that abides by usual preferential rules, and one (the potential leaders) connecting via anti-preferential attachments, i.e. selecting lower degree nodes for their initial links. The latter nodes come to develop a higher average degree, and convert eventually into the final hubs....

  10. Modes of Collaboration in Modern Science - Beyond Power Laws and Preferential Attachment

    CERN Document Server

    Milojević, Staša

    2010-01-01

    The goal of the study is to determine the underlying processes leading to the observed collaborator distribution in modern scientific fields, with special attention to non-power law behavior. Nanoscience is used as a case study of a modern interdisciplinary field, and its coauthorship network for 2000-04 period is constructed from NanoBank database. We find three collaboration modes that correspond to three distinct ranges in the distribution of collaborators: (1) for authors with fewer than 20 collaborators (the majority) preferential attachment does not hold and they form a log-normal "hook" instead of a power law, (2) authors with more than 20 collaborators benefit from preferential attachment and form a power law tail, and (3) authors with between 250 and 800 collaborators are more frequent than expected because of the hyperauthorship practices in certain subfields.

  11. Estimation of Airline Benefits from Avionics Upgrade under Preferential Merge Re-sequence Scheduling

    Science.gov (United States)

    Kotegawa, Tatsuya; Cayabyab, Charlene Anne; Almog, Noam

    2013-01-01

    Modernization of the airline fleet avionics is essential to fully enable future technologies and procedures for increasing national airspace system capacity. However in the current national airspace system, system-wide benefits gained by avionics upgrade are not fully directed to aircraft/airlines that upgrade, resulting in slow fleet modernization rate. Preferential merge re-sequence scheduling is a best-equipped-best-served concept designed to incentivize avionics upgrade among airlines by allowing aircraft with new avionics (high-equipped) to be re-sequenced ahead of aircraft without the upgrades (low-equipped) at enroute merge waypoints. The goal of this study is to investigate the potential benefits gained or lost by airlines under a high or low-equipped fleet scenario if preferential merge resequence scheduling is implemented.

  12. Introducing Fractal Dimension to Estimation of Soil Sensitivity to Preferential Flow

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Food dye Brilliant Blue was introduced as the tracer in a dye-tracing experiment to obtain dye profile patterns of sandy loam soil, aeolian sandy soil, percolating paddy soil and permeable paddy soil. The dyed soil profiles were then photographed and the photos were scanned into a computer. Edited with certain software, only the dyed areas were left on the profile photos, which indicted the preferential flow paths for water and solute transport. Fractal dimensions of the dye patterns were calculated according to Arnold's function. Soil particle size distribution was analyzed by pipette method. The regression analysis showed that there was significant relationship between soil clay content and fractal dimension D of the dye pattern of soil profile. Based on the experiment results, the possibility of introducing fractal dimension to estimation of soil sensitivity to preferential flow is discussed.

  13. Zinc as Allosteric Ion Channel Modulator: Ionotropic Receptors as Metalloproteins.

    Science.gov (United States)

    Peralta, Francisco Andrés; Huidobro-Toro, Juan Pablo

    2016-01-01

    Zinc is an essential metal to life. This transition metal is a structural component of many proteins and is actively involved in the catalytic activity of cell enzymes. In either case, these zinc-containing proteins are metalloproteins. However, the amino acid residues that serve as ligands for metal coordination are not necessarily the same in structural proteins compared to enzymes. While crystals of structural proteins that bind zinc reveal a higher preference for cysteine sulfhydryls rather than histidine imidazole rings, catalytic enzymes reveal the opposite, i.e., a greater preference for the histidines over cysteines for catalysis, plus the influence of carboxylic acids. Based on this paradigm, we reviewed the putative ligands of zinc in ionotropic receptors, where zinc has been described as an allosteric modulator of channel receptors. Although these receptors do not strictly qualify as metalloproteins since they do not normally bind zinc in structural domains, they do transitorily bind zinc at allosteric sites, modifying transiently the receptor channel's ion permeability. The present contribution summarizes current information showing that zinc allosteric modulation of receptor channels occurs by the preferential metal coordination to imidazole rings as well as to the sulfhydryl groups of cysteine in addition to the carboxyl group of acid residues, as with enzymes and catalysis. It is remarkable that most channels, either voltage-sensitive or transmitter-gated receptor channels, are susceptible to zinc modulation either as positive or negative regulators. PMID:27384555

  14. Medication in nursing homes in Alsace: a preferential list of drugs obtained by consensus

    OpenAIRE

    Hannou, Sophia; Rousseau, Amélie; Rybarczyk-Vigouret, Marie-Christine; Michel, Bruno

    2014-01-01

    Abstract In order to improve patient care, OMEDIT (Observatory of drugs, medical devices and therapeutic innovation) Alsace, conducted a study to develop a Preferential list of Drugs adapted to the Elderly (PDE list) in nursing homes. The study conducted from December 2011 to June 2012 was organized in 4 phases: 1) creation of a preliminary list of drugs from those currently used in nursing homes in Alsace, 2) application of a two-round Delphi process to evaluate the preliminary list involvin...

  15. Modeling, Analysis and Simulation of Multiscale Preferential Flow - 8/05-8/10 - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Ralph Showalter; Malgorzata Peszynska

    2012-07-03

    The research agenda of this project are: (1) Modeling of preferential transport from mesoscale to macroscale; (2) Modeling of fast flow in narrow fractures in porous media; (3) Pseudo-parabolic Models of Dynamic Capillary Pressure; (4) Adaptive computational upscaling of flow with inertia from porescale to mesoscale; (5) Adaptive modeling of nonlinear coupled systems; and (6) Adaptive modeling and a-posteriori estimators for coupled systems with heterogeneous data.

  16. SEPARATION OF MAGNESIUM CHLORIDE FROM SEA WATER BY PREFERENTIAL SALT SEPARATION (PSS)

    OpenAIRE

    Khaled Zohdy, Maha Abdel Kareem and Hussein Abdel-Aal*

    2013-01-01

    Magnesium chloride is typically extracted from sea water on an industrial scale by precipitating it as magnesium hydroxide, then converting it to the chloride by adding hydrochloric acid. This process is known as the Dow process which uses the chemical approach in producing magnesium chloride. Kettani and Abdel-Aal [1], proposed a physical separation procedure known as the Preferential Salt Separation (PSS) to obtain magnesium chloride directly from sea water. In principle, the PSS concept is...

  17. Power laws in preferential attachment graphs and Stein's method for the negative binomial distribution

    OpenAIRE

    Ross, Nathan

    2013-01-01

    For a family of linear preferential attachment graphs, we provide rates of convergence for the total variation distance between the degree of a randomly chosen vertex and an appropriate power law distribution as the number of vertices tends to infinity. Our proof uses a new formulation of Stein's method for the negative binomial distribution, which stems from a distributional transformation that has the negative binomial distributions as the only fixed points.

  18. The Pif1 Helicase, a Negative Regulator of Telomerase, Acts Preferentially at Long Telomeres

    OpenAIRE

    Jane A Phillips; Angela Chan; Katrin Paeschke; Zakian, Virginia A.

    2015-01-01

    Telomerase, the enzyme that maintains telomeres, preferentially lengthens short telomeres. The S. cerevisiae Pif1 DNA helicase inhibits both telomerase-mediated telomere lengthening and de novo telomere addition at double strand breaks (DSB). Here, we report that the association of the telomerase subunits Est2 and Est1 at a DSB was increased in the absence of Pif1, as it is at telomeres, suggesting that Pif1 suppresses de novo telomere addition by removing telomerase from the break. To determ...

  19. Preferential Acceleration of Coherent Magnetic Structures and Bursty Bulk Flows in Earth's Magnetotail

    CERN Document Server

    Chang, T; Angelopoulos, V; Chang, Tom; Wu, Cheng-chin; Angelopoulos, Vassilis

    2001-01-01

    Observations indicate that the magnetotail convection is turbulent and bi-modal, consisting of fast bursty bulk flows (BBF) and a nearly stagnant background. We demonstrate that this observed phenomenon may be understood in terms of the intermittent interactions, dynamic mergings and preferential accelerations of coherent magnetic structures under the influence of a background magnetic field geometry that is consistent with the development of an X-point mean-field structure.

  20. Preferential traits for breeding Nguni cattle in low-input in-situ conservation production systems

    OpenAIRE

    Tada, Obert; Muchenje, Voster; Dzama, Kennedy

    2013-01-01

    A cross-sectional study was conducted in communal and small-scale Nguni cattle enterprises to determine preferential traits for improvement under low-input cattle breeding programs. Forty-one farmers participated in ranking six specific traits of breeding bulls and cows. Kruskal-Wallis test and ordinal logistic regression were used to determine mean ranks of traits and odds ratios of predictors (enterprise ownership, gender, farmer age, education level, agriculture training) on specified trai...