WorldWideScience

Sample records for networks degradation rates

  1. Photovoltaic Degradation Rates -- An Analytical Review

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D. C.; Kurtz, S. R.

    2012-06-01

    As photovoltaic penetration of the power grid increases, accurate predictions of return on investment require accurate prediction of decreased power output over time. Degradation rates must be known in order to predict power delivery. This article reviews degradation rates of flat-plate terrestrial modules and systems reported in published literature from field testing throughout the last 40 years. Nearly 2000 degradation rates, measured on individual modules or entire systems, have been assembled from the literature, showing a median value of 0.5%/year. The review consists of three parts: a brief historical outline, an analytical summary of degradation rates, and a detailed bibliography partitioned by technology.

  2. Shapley ratings in brain networks

    Directory of Open Access Journals (Sweden)

    Rolf Kötter

    2007-11-01

    Full Text Available Recent applications of network theory to brain networks as well as the expanding empirical databases of brain architecture spawn an interest in novel techniques for analyzing connectivity patterns in the brain. Treating individual brain structures as nodes in a directed graph model permits the application of graph theoretical concepts to the analysis of these structures within their large-scale connectivity networks. In this paper, we explore the application of concepts from graph and game theory toward this end. Specifically, we utilize the Shapley value principle, which assigns a rank to players in a coalition based upon their individual contributions to the collective profit of that coalition, to assess the contributions of individual brain structures to the graph derived from the global connectivity network. We report Shapley values for variations of a prefrontal network, as well as for a visual cortical network, which had both been extensively investigated previously. This analysis highlights particular nodes as strong or weak contributors to global connectivity. To understand the nature of their contribution, we compare the Shapley values obtained from these networks and appropriate controls to other previously described nodal measures of structural connectivity. We find a strong correlation between Shapley values and both betweenness centrality and connection density. Moreover, a stepwise multiple linear regression analysis indicates that approximately 79% of the variance in Shapley values obtained from random networks can be explained by betweenness centrality alone. Finally, we investigate the effects of local lesions on the Shapley ratings, showing that the present networks have an immense structural resistance to degradation. We discuss our results highlighting the use of such measures for characterizing the organization and functional role of brain networks.

  3. Analytical Improvements in PV Degradation Rate Determination

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D. C.; Kurtz, S. R.

    2011-02-01

    As photovoltaic (PV) penetration of the power grid increases, it becomes vital to know how decreased power output may affect cost over time. In order to predict power delivery, the decline or degradation rates must be determined accurately. For non-spectrally corrected data several complete seasonal cycles (typically 3-5 years) are required to obtain reasonably accurate degradation rates. In a rapidly evolving industry such a time span is often unacceptable and the need exists to determine degradation rates accurately in a shorter period of time. Occurrence of outliers and data shifts are two examples of analytical problems leading to greater uncertainty and therefore to longer observation times. In this paper we compare three methodologies of data analysis for robustness in the presence of outliers, data shifts and shorter measurement time periods.

  4. Estimating fractional rate of NDF degradation from in vivo digestibility

    DEFF Research Database (Denmark)

    Weisbjerg, Martin Riis; Søegaard, Karen; Lund, Peter

    2007-01-01

    Fractional rate of degradation (kd) of potential degradable NDF (dNDF) was estimated based on in situ degradation profiles.......Fractional rate of degradation (kd) of potential degradable NDF (dNDF) was estimated based on in situ degradation profiles....

  5. Overview of Field Experience - Degradation Rates & Lifetimes

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk; Kurtz, Sarah

    2015-09-14

    The way a PV module fails may depend not only on its design and the materials used in its construction, but also on the weather it experiences, the way it is mounted, and the quality control during its manufacture. This presentation gives an overview of Field Experience - what degradation rates and what lifetimes are being observed in various regions.

  6. PEG-based degradable networks for drug delivery applications

    Science.gov (United States)

    Ostroha, Jamie L.

    The controlled delivery of therapeutic agents by biodegradable hydrogels has become a popular mechanism for drug administration in recent years. Hydrogels are three-dimensional networks of polymer chains held together by crosslinks. Although the changes which the hydrogel undergoes in solution are important to a wide range of experimental studies, they have not been investigated systematically and the factors which influence the degree of swelling have not been adequately described. Hydrogels made of poly(ethylene glycol) (PEG) will generally resist degradation in aqueous conditions, while a hydrogel made from a copolymer of poly(lactic acid) (PLA) and PEG will degrade via hydrolysis of the lactic acid group. This ability to degrade makes these hydrogels promising candidates for controlled release drug delivery systems. The goal of this research was to characterize the swelling and degradation of both degradable and non-degradable gels and to evaluate the release of different drugs from these hydrogels, where the key variable is the molecular weight of the PEG segment. These hydrogels were formed by the addition and subsequent chemically crosslinking of methacrylate end groups. During crosslinking, both PEG and LA-PEG-LA hydrogels of varied PEG molecular weight were loaded with Vitamin B12, Insulin, Haloperidol, and Dextran. It was shown that increasing PEG molecular weight produces a hydrogel with larger pores, thus increasing water uptake and degradation rate. While many environmental factors do not affect the swelling behavior, they do significantly impact the degradation of the hydrogel, and thus the release of incorporated therapeutic agents.

  7. Degradable transportation network with the addition of electric vehicles: Network equilibrium analysis.

    Science.gov (United States)

    Zhang, Rui; Yao, Enjian; Yang, Yang

    2017-01-01

    Introducing electric vehicles (EVs) into urban transportation network brings higher requirement on travel time reliability and charging reliability. Specifically, it is believed that travel time reliability is a key factor influencing travelers' route choice. Meanwhile, due to the limited cruising range, EV drivers need to better learn about the required energy for the whole trip to make decisions about whether charging or not and where to charge (i.e., charging reliability). Since EV energy consumption is highly related to travel speed, network uncertainty affects travel time and charging demand estimation significantly. Considering the network uncertainty resulted from link degradation, which influences the distribution of travel demand on transportation network and the energy demand on power network, this paper aims to develop a reliability-based network equilibrium framework for accommodating degradable road conditions with the addition of EVs. First, based on the link travel time distribution, the mean and variance of route travel time and monetary expenses related to energy consumption are deduced, respectively. And the charging time distribution of EVs with charging demand is also estimated. Then, a nested structure is considered to deal with the difference of route choice behavior derived by the different uncertainty degrees between the routes with and without degradable links. Given the expected generalized travel cost and a psychological safety margin, a traffic assignment model with the addition of EVs is formulated. Subsequently, a heuristic solution algorithm is developed to solve the proposed model. Finally, the effects of travelers' risk attitude, network degradation degree, and EV penetration rate on network performance are illustrated through an example network. The numerical results show that the difference of travelers' risk attitudes does have impact on the route choice, and the widespread adoption of EVs can cut down the total system travel

  8. Degradable transportation network with the addition of electric vehicles: Network equilibrium analysis

    Science.gov (United States)

    Zhang, Rui; Yao, Enjian; Yang, Yang

    2017-01-01

    Introducing electric vehicles (EVs) into urban transportation network brings higher requirement on travel time reliability and charging reliability. Specifically, it is believed that travel time reliability is a key factor influencing travelers’ route choice. Meanwhile, due to the limited cruising range, EV drivers need to better learn about the required energy for the whole trip to make decisions about whether charging or not and where to charge (i.e., charging reliability). Since EV energy consumption is highly related to travel speed, network uncertainty affects travel time and charging demand estimation significantly. Considering the network uncertainty resulted from link degradation, which influences the distribution of travel demand on transportation network and the energy demand on power network, this paper aims to develop a reliability-based network equilibrium framework for accommodating degradable road conditions with the addition of EVs. First, based on the link travel time distribution, the mean and variance of route travel time and monetary expenses related to energy consumption are deduced, respectively. And the charging time distribution of EVs with charging demand is also estimated. Then, a nested structure is considered to deal with the difference of route choice behavior derived by the different uncertainty degrees between the routes with and without degradable links. Given the expected generalized travel cost and a psychological safety margin, a traffic assignment model with the addition of EVs is formulated. Subsequently, a heuristic solution algorithm is developed to solve the proposed model. Finally, the effects of travelers’ risk attitude, network degradation degree, and EV penetration rate on network performance are illustrated through an example network. The numerical results show that the difference of travelers’ risk attitudes does have impact on the route choice, and the widespread adoption of EVs can cut down the total system

  9. Diagnosing degradation of services in hybrid wireless tactical networks

    Science.gov (United States)

    Tati, Srikar; Novotny, Petr; Ko, Bong Jun; Wolf, Alexander; Swami, Ananthram; La Porta, Thomas

    2013-05-01

    In this paper, we consider a problem related to service management and deployment in tactical military networks. Tactical networks are typically hybrid wireless networks in which there are both static and mobile nodes with several wireless interfaces, such as 802.11, 3G, satellite, etc. In tactical networks, performance degradation in services could prove fatal, so it must be diagnosed quickly. This degradation could be due to mobility or bottlenecks in capacity at network layer. We provide a cross-layer framework to detect and diagnose these causes of performance degradation as part of service management; it includes a monitoring model of services and a network model for hybrid wireless networks. In addition, we give a working example in tactical military networks to illustrate our framework. We provide an experimental setup to simulate our hybrid wireless tactical network scenario along with preliminary results.

  10. On the Determination of Magnesium Degradation Rates under Physiological Conditions

    OpenAIRE

    Nidadavolu, Eshwara Phani Shubhakar; Feyerabend, Frank; Ebel, Thomas; Willumeit-R?mer, Regine; Dahms, Michael

    2016-01-01

    The current physiological in vitro tests of Mg degradation follow the procedure stated according to the ASTM standard. This standard, although useful in predicting the initial degradation behavior of an alloy, has its limitations in interpreting the same for longer periods of immersion in cell culture media. This is an important consequence as the alloy?s degradation is time dependent. Even if two different alloys show similar corrosion rates in a short term experiment, their degradation char...

  11. Fire danger rating network density

    Science.gov (United States)

    Rudy M. King; R. William Furman

    1976-01-01

    Conventional statistical techniques are used to answer the question, "What is the necessary station density for a fire danger network?" The Burning Index of the National Fire-Danger Rating System is used as an indicator of fire danger. Results are presented as station spacing in tabular form for each of six regions in the western United States.

  12. On the Determination of Magnesium Degradation Rates under Physiological Conditions.

    Science.gov (United States)

    Nidadavolu, Eshwara Phani Shubhakar; Feyerabend, Frank; Ebel, Thomas; Willumeit-Römer, Regine; Dahms, Michael

    2016-07-28

    The current physiological in vitro tests of Mg degradation follow the procedure stated according to the ASTM standard. This standard, although useful in predicting the initial degradation behavior of an alloy, has its limitations in interpreting the same for longer periods of immersion in cell culture media. This is an important consequence as the alloy's degradation is time dependent. Even if two different alloys show similar corrosion rates in a short term experiment, their degradation characteristics might differ with increased immersion times. Furthermore, studies concerning Mg corrosion extrapolate the corrosion rate from a single time point measurement to the order of a year (mm/y), which might not be appropriate because of time dependent degradation behavior. In this work, the above issues are addressed and a new methodology of performing long-term immersion tests in determining the degradation rates of Mg alloys was put forth. For this purpose, cast and extruded Mg-2Ag and powder pressed and sintered Mg-0.3Ca alloy systems were chosen. DMEM Glutamax +10% FBS (Fetal Bovine Serum) +1% Penicillin streptomycin was used as cell culture medium. The advantages of such a method in predicting the degradation rates in vivo deduced from in vitro experiments are discussed.

  13. Protein Degradation Rate in Arabidopsis thaliana Leaf Growth and Development.

    Science.gov (United States)

    Li, Lei; Nelson, Clark J; Trösch, Josua; Castleden, Ian; Huang, Shaobai; Millar, A Harvey

    2017-02-01

    We applied 15N labeling approaches to leaves of the Arabidopsis thaliana rosette to characterize their protein degradation rate and understand its determinants. The progressive labeling of new peptides with 15N and measuring the decrease in the abundance of >60,000 existing peptides over time allowed us to define the degradation rate of 1228 proteins in vivo. We show that Arabidopsis protein half-lives vary from several hours to several months based on the exponential constant of the decay rate for each protein. This rate was calculated from the relative isotope abundance of each peptide and the fold change in protein abundance during growth. Protein complex membership and specific protein domains were found to be strong predictors of degradation rate, while N-end amino acid, hydrophobicity, or aggregation propensity of proteins were not. We discovered rapidly degrading subunits in a variety of protein complexes in plastids and identified the set of plant proteins whose degradation rate changed in different leaves of the rosette and correlated with leaf growth rate. From this information, we have calculated the protein turnover energy costs in different leaves and their key determinants within the proteome. © 2017 American Society of Plant Biologists. All rights reserved.

  14. Degradation rate of sodium fluoroacetate in three New Zealand soils.

    Science.gov (United States)

    Northcott, Grant; Jensen, Dwayne; Ying, Lucia; Fisher, Penny

    2014-05-01

    The degradation rate of sodium fluoroacetate (SFA) was assessed in a laboratory microcosm study incorporating 3 New Zealand soil types under different temperature (5 °C, 10 °C, or 20 °C) and soil moisture (35% or 60% water holding capacity) conditions using guideline 307 from the Organisation for Economic Co-operation and Development. A combination of nonlabeled and radiolabeled (14) C-SFA was added to soil microcosms, with sampling and analysis protocols for soil, soil extracts, and evolved CO(2) established using liquid scintillation counting and liquid chromatography-mass spectrometry. Degradation products of SFA and their rates of formation were similar in the 3 soil types. The major degradation pathway for SFA was through microbial degradation to the hydroxyl metabolite, hydroxyacetic acid, and microbial mineralization to CO(2), which constituted the major transformation product. Temperature, rather than soil type or moisture content, was the dominant factor affecting the rate of degradation. Soil treatments incubated at 20 °C displayed a more rapid loss of (14)C-SFA residues than lower temperature treatments. The transformation half-life (DT50) of SFA in the 3 soils increased with decreasing temperature, varying from 6 d to 8 d at 20 °C, 10 d to 21 d at 10 °C, and 22 d to 43 d at 5 °C. © 2014 SETAC.

  15. Evaluation of Network Failure induced IPTV degradation in Metro Networks

    DEFF Research Database (Denmark)

    Wessing, Henrik; Berger, Michael Stübert; Yu, Hao

    2009-01-01

    In this paper, we evaluate future network services and classify them according to their network requirements. IPTV is used as candidate service to evaluate the performance of Carrier Ethernet OAM update mechanisms and requirements. The latter is done through quality measurements using MDI...... and subjective evaluations. It is concluded that OAM interval close to 10 ms is a suitable choice for service providers....

  16. Sequence-based analysis of protein degradation rates

    NARCIS (Netherlands)

    Correa Marrero, Miguel; Dijk, van Aalt-Jan; Ridder, de Dick

    2017-01-01

    Protein turnover is a key aspect of cellular homeostasis and proteome dynamics. However, there is little consensus on which properties of a protein determine its lifetime in the cell. In this work, we exploit two reliable datasets of experimental protein degradation rates to learn models and uncover

  17. Metal dusting: relationship between alloy composition and degradation rate

    NARCIS (Netherlands)

    Hermse, C.G.M.; Wortel, J.C. van

    2009-01-01

    The authors have identified a compositional relationship between several commercially available wrought alloys, focussing only on the iron, nickel, chromium and aluminium content. The degradation rate due to metal dusting varies with the surface condition of each alloy: a ground surface condition

  18. Peer Ratings in Massive Online Social Networks

    OpenAIRE

    Zinoviev, Dmitry

    2014-01-01

    Instant quality feedback in the form of online peer ratings is a prominent feature of modern massive online social networks (MOSNs). It allows network members to indicate their appreciation of a post, comment, photograph, etc. Some MOSNs support both positive and negative (signed) ratings. In this study, we rated 11 thousand MOSN member profiles and collected user responses to the ratings. MOSN users are very sensitive to peer ratings: 33% of the subjects visited the researcher's profile in r...

  19. 9975 Shipping package component long-term degradation rates

    Energy Technology Data Exchange (ETDEWEB)

    Daugherty, W. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-06-28

    Special nuclear materials are being stored in the K-Area Complex using 3013 containers that are held within Model 9975 shipping packages. The service life for these packages in storage was recently increased from 15 to 20 years, since some of these packages have been stored for nearly 15 years. A strategy is also being developed whereby such storage might be extended beyond 20 years. This strategy is based on recent calculations that support acceptable 9975 package performance for 20 years with internal heat loads up to 19 watts, and identifies a lower heat load limit for which the package components should degrade at half the bounding rate or less, thus doubling the effective storage life for these lower wattage packages. The components of the 9975 package that are sensitive to aging under storage conditions are the fiberboard overpack and the O-ring seals, although some degradation of the lead shield and outer drum are also possible. This report summarizes degradation rates applicable to lower heat load storage conditions. In particular, the O-ring seals should provide leak-tight performance for more than 40 years in packages for which their maximum temperature is ≤135 °F. Similarly, the fiberboard should remain acceptable in performance of its required safety functions for up to 40 years in packages with a maximum fiberboard temperature ≤125 °F.

  20. Influence of the dose rate in the PVDF degradation processes

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Adriana S.M.; Pereira, Claubia, E-mail: adriananuclear@yahoo.com.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Gual, Maritza R., E-mail: maritzargual@gmail.com [Instituto Superior de Tecnologias y Ciencias Aplicadas (InsTEC), Departamento de Ingenieria Nuclear, La Habana (Cuba); Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from gamma radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation by products such as peroxide degradation. Radiation cross-linking technologies include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, polymer recycling, hydrogels etc. The degradation of PVDF polymer exposed to gamma irradiation in oxygen atmosphere in high dose rate has been studied and compared to obtained under smaller dose rates. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h and 2,592 kGy/h), with doses ranging from 100 kGy to 3,000 kGy. Different dose rate determine the prevalence of the processes being evaluated in this work by thermal measurements and infrared spectroscopy. It is shown that the degradation processes involve chain scissions and crosslink formation. The formation of oxidation products was shown at the surface of the irradiated film. The FTIR data revealed absorption bands at 1730 and 1853 cm{sup -1} which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm{sup -1} which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm{sup -1} which were associated with NH stretch of NH{sub 2} and OH. Thermogravimetric studies reveal that the irradiation induced the increasing residues and decrease of the temperature of the decomposition start. (author)

  1. Distributed Rate Allocation for Wireless Networks

    CERN Document Server

    Jose, Jubin

    2010-01-01

    This paper describes a distributed algorithm for rate allocation in wireless networks. As the main result, the paper establishes that this algorithm is throughput-optimal for very general class of throughput regions. In contrast to distributed on-off scheduling algorithms, this algorithm enables optimal utilization of physical layer schemes by scheduling multiple rate levels. The algorithm is based on a Markov process on these discrete set of rates with certain transition rates. For dealing with multiple rate levels, the paper introduces an important structure for the transition rates, which enable the design of appropriate update rule for these transition rates. The update uses local queue length information alone, and thus does not require global exchange of queue length information. In addition, the algorithm requires that each link can determine the feasibility of increasing its data-rate from the current value without reducing the data-rates of other links. Determining rate feasibility does not introduce...

  2. Quantitative response relationships between degradation rates and functional genes during the degradation of beta-cypermethrin in soil.

    Science.gov (United States)

    Yang, Zhong-Hua; Ji, Guo-Dong

    2015-12-15

    In the present study, the degradation mechanisms of beta-cypermethrin and its metabolites in soil were explored through the quantitative response relationships between the degradation rates and related functional genes. We found that the degradation rate of beta-cypermethrin was rapid in unsterilized soil but not in sterilized soil, which indicated that the degradation process is microbially based. Moreover, three metabolites (3-phenoxybenzoic acid, phenol and protocatechuic acid) were detected during the degradation process and used to identify the degradation pathway and functional genes related to the degradation process. The key rate-limiting functional genes were pytH and pobA, and the relative contributions of these genes to the degradation process were examined with a path analysis. The path analysis revealed that the genes pobA and pytH had the greatest direct effects on the degradation of beta-cypermethrin (pobA), alpha-cypermethrin (pobA), theta-cypermethrin (pytH) and 3-phenoxybenzoic acid (pytH). Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Thermo-Mechanical Properties of Semi-Degradable Poly(β-amino ester)-co-Methyl Methacrylate Networks under Simulated Physiological Conditions.

    Science.gov (United States)

    Safranski, David L; Crabtree, Jacob C; Huq, Yameen R; Gall, Ken

    2011-09-29

    Poly(β-amino ester) networks are being explored for biomedical applications, but they may lack the mechanical properties necessary for long term implantation. The objective of this study is to evaluate the effect of adding methyl methacrylate on networks' mechanical properties under simulated physiological conditions. The networks were synthesized in two parts: (1) a biodegradable crosslinker was formed from a diacrylate and amine, (2) and then varying concentrations of methyl methacrylate were added prior to photopolymerizing the network. Degradation rate, mechanical properties, and glass transition temperature were studied as a function of methyl methacrylate composition. The crosslinking density played a limited role on mechanical properties for these networks, but increasing methyl methacrylate concentration improved the toughness by several orders of magnitude. Under simulated physiological conditions, networks showed increasing toughness or sustained toughness as degradation occurred. This work establishes a method of creating degradable networks with tailorable toughness while undergoing partial degradation.

  4. Rate-Based Active Queue Management for TCP Flows over Wired and Wireless Networks

    OpenAIRE

    Jun Wang; Min Song

    2007-01-01

    Current active queue management (AQM) and TCP protocol are designed and tuned to work well on wired networks where packet loss is mainly due to network congestion. In wireless networks, however, communication links suffer from significant transmission bit errors and handoff failures. As a result, the performance of TCP flows is significantly degraded. To mitigate this problem, we analyze existing AQM schemes and propose a rate-based exponential AQM (REAQM) scheme. The proposed REAQM scheme u...

  5. Artificial Neural Network Modeling of Pt/C Cathode Degradation in PEM Fuel Cells

    Science.gov (United States)

    Maleki, Erfan; Maleki, Nasim

    2016-08-01

    Use of computational modeling with a few experiments is considered useful to obtain the best possible result for a final product, without performing expensive and time-consuming experiments. Proton exchange membrane fuel cells (PEMFCs) can produce clean electricity, but still require further study. An oxygen reduction reaction (ORR) takes place at the cathode, and carbon-supported platinum (Pt/C) is commonly used as an electrocatalyst. The harsh conditions during PEMFC operation result in Pt/C degradation. Observation of changes in the Pt/C layer under operating conditions provides a tool to study the lifetime of PEMFCs and overcome durability issues. Recently, artificial neural networks (ANNs) have been used to solve, predict, and optimize a wide range of scientific problems. In this study, several rates of change at the cathode were modeled using ANNs. The backpropagation (BP) algorithm was used to train the network, and experimental data were employed for network training and testing. Two different models are constructed in the present study. First, the potential cycles, temperature, and humidity are used as inputs to predict the resulting Pt dissolution rate of the Pt/C at the cathode as the output parameter of the network. Thereafter, the Pt dissolution rate and Pt ion diffusivity are regarded as inputs to obtain values of the Pt particle radius change rate, Pt mass loss rate, and surface area loss rate as outputs. The networks are finely tuned, and the modeling results agree well with experimental data. The modeled responses of the ANNs are acceptable for this application.

  6. Degradation Prediction Model Based on a Neural Network with Dynamic Windows

    Directory of Open Access Journals (Sweden)

    Xinghui Zhang

    2015-03-01

    Full Text Available Tracking degradation of mechanical components is very critical for effective maintenance decision making. Remaining useful life (RUL estimation is a widely used form of degradation prediction. RUL prediction methods when enough run-to-failure condition monitoring data can be used have been fully researched, but for some high reliability components, it is very difficult to collect run-to-failure condition monitoring data, i.e., from normal to failure. Only a certain number of condition indicators in certain period can be used to estimate RUL. In addition, some existing prediction methods have problems which block RUL estimation due to poor extrapolability. The predicted value converges to a certain constant or fluctuates in certain range. Moreover, the fluctuant condition features also have bad effects on prediction. In order to solve these dilemmas, this paper proposes a RUL prediction model based on neural network with dynamic windows. This model mainly consists of three steps: window size determination by increasing rate, change point detection and rolling prediction. The proposed method has two dominant strengths. One is that the proposed approach does not need to assume the degradation trajectory is subject to a certain distribution. The other is it can adapt to variation of degradation indicators which greatly benefits RUL prediction. Finally, the performance of the proposed RUL prediction model is validated by real field data and simulation data.

  7. Pathway and rate-limiting step of glyphosate degradation by Aspergillus oryzae A-F02.

    Science.gov (United States)

    Fu, Gui-Ming; Chen, Yan; Li, Ru-Yi; Yuan, Xiao-Qiang; Liu, Cheng-Mei; Li, Bin; Wan, Yin

    2017-09-14

    Aspergillus oryzae A-F02, a glyphosate-degrading fungus, was isolated from an aeration tank in a pesticide factory. The pathway and rate-limiting step of glyphosate (GP) degradation were investigated through metabolite analysis. GP, aminomethylphosphonic acid (AMPA), and methylamine were detected in the fermentation liquid of A. oryzae A-F02, whereas sarcosine and glycine were not. The pathway of GP degradation in A. oryzae A-F02 was revealed: GP was first degraded into AMPA, which was then degraded into methylamine. Finally, methylamine was further degraded into other products. Investigating the effects of the exogenous addition of substrates and metabolites showed that the degradation of GP to AMPA is the rate-limiting step of GP degradation by A. oryzae A-F02. In addition, the accumulation of AMPA and methylamine did not cause feedback inhibition in GP degradation. Results showed that degrading GP to AMPA was a crucial step in the degradation of GP, which determines the degradation rate of GP by A. oryzae A-F02.

  8. Relative saccharification and initial degradation rates of different ...

    African Journals Online (AJOL)

    A structural analysis revealed that cellulose, a major component of waste paper, is a biopolymer composed of glucose units and when treated with cellulase enzymes, cellulose can be degraded into glucose a fermentable sugar. The aim of this investigation was to determine the relative saccharification of various waste ...

  9. Lifetime Evaluation of PV Inverters considering Panel Degradation Rates and Installation Sites

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Sera, Dezso

    2017-01-01

    The PV inverter lifetime is affected by the installed sites related to different solar irradiance and ambient temperature profiles. In fact, the installation site also affects the PV panel degradation rate, and thus the long-term power production. Prior-art lifetime analysis in PV inverters has...... not yet investigated the impact of panel degradation. This paper thus evaluates the lifetime of PV inverters considering panel degradation rates and installation sites. Evaluations have been carried out on PV systems installed in Denmark and Arizona. The results reveal that the PV panel degradation rate...... has a considerable impact on the PV inverter lifetime, especially in the hot climate (e.g., Arizona), where the panel degrades at a faster rate. In that case, the PV inverter lifetime estimation can be deviated by 54%, if the impact of PV panel degradation is not taken into account....

  10. Use of Pyranometers to Estimate PV Module Degradation Rates in the Field

    Energy Technology Data Exchange (ETDEWEB)

    Vignola, Frank; Peterson, Josh; Kessler, Rich; Mavromatakis, Fotis; Dooraghi, Mike; Sengupta, Manajit

    2016-06-05

    This poster provides an overview of a methodology that uses relative measurements to estimate the degradation rates of PV modules in the field. The importance of calibration and cleaning is illustrated. The number of years of field measurements needed to measure degradation rates with data from the field is cut in half using relative comparisons.

  11. Use of Pyranometers to Estimate PV Module Degradation Rates in the Field: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Vignola, Frank; Peterson, Josh; Kessler, Rich; Mavromatakis, Fotis; Dooraghi, Mike; Sengupta, Manajit

    2016-08-01

    This paper describes a methodology that uses relative measurements to estimate the degradation rates of PV modules in the field. The importance of calibration and cleaning is illustrated. The number of years of field measurements needed to measure degradation rates with data from the field is cut in half using relative comparisons.

  12. Modeling network technology deployment rates with different network models

    OpenAIRE

    Chung, Yoo

    2011-01-01

    To understand the factors that encourage the deployment of a new networking technology, we must be able to model how such technology gets deployed. We investigate how network structure influences deployment with a simple deployment model and different network models through computer simulations. The results indicate that a realistic model of networking technology deployment should take network structure into account.

  13. Biologically Safe Poly(l-lactic acid) Blends with Tunable Degradation Rate: Microstructure, Degradation Mechanism, and Mechanical Properties.

    Science.gov (United States)

    Oyama, Hideko T; Tanishima, Daisuke; Ogawa, Ryohei

    2017-04-10

    Although poly(l-lactic acid) (PLLA) is reputed to be biodegradable in the human body, its hydrophobic nature lets it persist for ca. 5.5 years. This study demonstrates that biologically safe lactide copolymers, poly(aspartic acid-co-l-lactide) (PAL) and poly(malic acid-co-l-lactide) (PML), dispersed in the PLLA function as detonators (triggers) for its hydrolytic degradation under physiological conditions. The copolymers significantly enhance hydrolysis, and consequently, the degradation rate of PLLA becomes easily tunable by controlling the amounts of PAL and PML. The present study elucidates the effects of uniaxial drawing on the structural development, mechanical properties, and hydrolytic degradation under physiological conditions of PLLA blend films. At initial degradation stages, the mass loss was not affected by uniaxial drawing; however, at late degradation stages, less developed crystals as well as amorphous chains were degradable at low draw ratio (DR), whereas not only highly developed crystals but also the oriented amorphous chains became insensitive to hydrolysis at high DR. Our work provides important molecular level results that demonstrate that biodegradable materials can have superb mechanical properties and also disappear in a required time under physiological conditions.

  14. Rate Aware Instantly Decodable Network Codes

    KAUST Repository

    Douik, Ahmed

    2016-02-26

    This paper addresses the problem of reducing the delivery time of data messages to cellular users using instantly decodable network coding (IDNC) with physical-layer rate awareness. While most of the existing literature on IDNC does not consider any physical layer complications, this paper proposes a cross-layer scheme that incorporates the different channel rates of the various users in the decision process of both the transmitted message combinations and the rates with which they are transmitted. The completion time minimization problem in such scenario is first shown to be intractable. The problem is, thus, approximated by reducing, at each transmission, the increase of an anticipated version of the completion time. The paper solves the problem by formulating it as a maximum weight clique problem over a newly designed rate aware IDNC (RA-IDNC) graph. Further, the paper provides a multi-layer solution to improve the completion time approximation. Simulation results suggest that the cross-layer design largely outperforms the uncoded transmissions strategies and the classical IDNC scheme. © 2015 IEEE.

  15. Lifetime Evaluation of Grid-Connected PV Inverters Considering Panel Degradation Rates and Installation Sites

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Sera, Dezso

    2018-01-01

    Lifetime of PV inverters is affected by the installation sites related to different solar irradiance and ambient temperature profiles (also referred to as mission profiles). In fact, the installation site also affects the degradation rate of the PV panels, and thus long-term energy production...... and reliability. Prior-art lifetime analysis in PV inverters has not yet investigated the impact of PV panel degradations. This paper thus evaluates the lifetime of PV inverters considering panel degradation rates and mission profiles. Evaluations have been carried out on PV systems installed in Denmark...... and Arizona. The results reveal that the PV panel degradation rate has a considerable impact on the PV inverter lifetime, especially in the hot climate (e.g., Arizona), where the panel degrades at a faster rate. In that case, the PV inverter lifetime prediction can be deviated by 54%, if the impact of PV...

  16. Networking Technologies and the Rate of Technological Change

    Directory of Open Access Journals (Sweden)

    Charles Mitchell

    2005-12-01

    Full Text Available Network technology is changing rapidly and those adept at ICT analysis need resolve rate of change issues. Developments in networking now are in the direction of heuristic intelligence. Since about 1980, networking techniques have encouraged combining bits of information with imagination cognitively to improve ideas about reality. ICT enterprise projects utilize networking to sustain requisite imagination. Assumptions and misassuptions of project builders are rationally comprehended as networking sustains creative processes. The monopolization of valuable network techniques influences in the direction of esoteric networking. Data presents that substantial knowledge and networking is now occurring globally. As a netaphor, networking

  17. Altered Micro-RNA Degradation Promotes Tumor Heterogeneity: A Result from Boolean Network Modeling.

    Science.gov (United States)

    Wu, Yunyi; Krueger, Gerhard R F; Wang, Guanyu

    2016-02-01

    Cancer heterogeneity may reflect differential dynamical outcomes of the regulatory network encompassing biomolecules at both transcriptional and post-transcriptional levels. In other words, differential gene-expression profiles may correspond to different stable steady states of a mathematical model for simulation of biomolecular networks. To test this hypothesis, we simplified a regulatory network that is important for soft-tissue sarcoma metastasis and heterogeneity, comprising of transcription factors, micro-RNAs, and signaling components of the NOTCH pathway. We then used a Boolean network model to simulate the dynamics of this network, and particularly investigated the consequences of differential miRNA degradation modes. We found that efficient miRNA degradation is crucial for sustaining a homogenous and healthy phenotype, while defective miRNA degradation may lead to multiple stable steady states and ultimately to carcinogenesis and heterogeneity. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  18. Fractional rate of degradation (kd) of starch in the rumen and its ...

    African Journals Online (AJOL)

    Ruminal starch pool was estimated from rumen evacuation and starch flow was estimated by duodenal and faeces sampling. Fractional rate of rumen degradation was estimated from the equation [kd = rumen degraded/rumen pool] and rumen and total digestibility of starch from flow measurements. The relation between kd ...

  19. Customizing the hydrolytic degradation rate of stereocomplex PLA through different PDLA architectures.

    Science.gov (United States)

    Andersson, Sofia Regnell; Hakkarainen, Minna; Inkinen, Saara; Södergård, Anders; Albertsson, Ann-Christine

    2012-04-09

    Stereocomplexation of poly(L-lactide) (PLLA) with star shaped D-lactic acid (D-LA) oligomers with different architectures and end-groups clearly altered the degradation rate and affected the degradation product patterns. Altogether, nine materials were studied: standard PLLA and eight blends of PLLA with either 30 or 50 wt % of four different D-LA oligomers. The influence of several factors, including temperature, degradation time, and amount and type of D-LA oligomer, on the hydrolytic degradation process was investigated using a fractional factorial experimental design. Stereocomplexes containing star shaped D-LA oligomers with four alcoholic end-groups underwent a rather slow hydrolytic degradation with low release of degradation products. Materials with linear D-LA oligomers exhibited similar mass loss but released higher concentrations of shorter acidic degradation products. Increasing the fraction of D-LA oligomers with a linear structure or with four alcoholic end-groups resulted in slower mass loss due to higher degree of stereocomplexation. The opposite results were obtained after addition of D-LA oligomers with carboxylic chain-ends. These materials demonstrated lower degree of stereocomplexation and larger mass and molar mass loss, and also the release of degradation products increased. Increasing the number of alcoholic chain-ends from four to six decreased the degree of stereocomplexation, leading to faster mass loss. The degree of stereocomplexation and degradation rate were customized by changing the architecture and end-groups of the D-LA oligomers.

  20. Rate and extent of ruminal degradation of crude protein from ...

    African Journals Online (AJOL)

    The rate constant for outflow was correlated with level of DM intake (r2 = 0.87). Lag phase prior to degrada- tion of crude ... at a level of 7% for the whole maize and 11% for the maize meal and flaked maize diets. Urea was .... have been affected by both the particle type and the math- ematical model we used. Crude protein ...

  1. Effect of application rate on fumigant degradation in five agricultural soils.

    Science.gov (United States)

    Qin, Ruijun; Gao, Suduan; Ajwa, Husein; Hanson, Bradley D

    2016-01-15

    Soil fumigation is an important pest management tool for many high value crops. To address the knowledge gap of how fumigant concentration in soil impacts dissipation, and thereby efficacy, this research determined the degradation characteristics of four fumigants as affected by application rate. Laboratory incubation experiments were conducted to determine degradation rates of 1,3-dichloropropene (both cis- and trans isomers), chloropicrin (CP), dimethyl disulfide (DMDS), and methyl iodide (MeI) in five agricultural soils. Fitted to pseudo first-order kinetics, the degradation rate constant (k) of CP, DMDS, and MeI decreased significantly as application rate increased while the 1,3-D isomers were the least affected by rate. Half-lives increased 12, 17, and 6-fold for CP, DMDS, and MeI, respectively, from the lowest to the highest application rate. At low application rates, the degradation rate of all fumigants in the Hueneme sandy loam soil was reduced by 50-95% in sterilized soil compared to the biologically active controls. However, this difference became much smaller or disappeared at high application rates indicating that biodegradation dominates at low concentrations but chemical degradation is more important at high concentrations. When co-applied, CP degradation was enhanced with biodegradation remained above 50%, while 1,3-D degradation was either reduced or not changed. Among the fumigants tested, the relative importance of biodegradation was DMDS>CP>MeI>1,3-D. These results are useful for determining effective fumigation rates and for informing regulatory decisions on emission controls under different fumigation scenarios. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Identification of dichloroacetic acid degrading Cupriavidus bacteria in a drinking water distribution network model.

    Science.gov (United States)

    Berthiaume, C; Gilbert, Y; Fournier-Larente, J; Pluchon, C; Filion, G; Jubinville, E; Sérodes, J-B; Rodriguez, M; Duchaine, C; Charette, S J

    2014-01-01

    Bacterial community structure and composition of a drinking water network were assessed to better understand this ecosystem in relation to haloacetic acid (HAA) degradation and to identify new bacterial species having HAA degradation capacities. Biofilm samples were collected from a model system, simulating the end of the drinking water distribution network and supplied with different concentrations of dichloroacetic and trichloroacetic acids at different periods over the course of a year. The samples were analysed by culturing, denaturing gradient gel electrophoresis (DGGE) and sequencing. Pipe diameter and HAA ratios did not impact the bacterial community profiles, but the season had a clear influence. Based on DGGE profiles, it appeared that a particular biomass has developed during the summer compared with the other seasons. Among the bacteria isolated in this study, those from genus Cupriavidus were able to degrade dichloroacetic acid. Moreover, these bacteria degrade dichloroacetic acid at 18°C but not at 10°C. The microbial diversity evolved throughout the experiment, but the bacterial community was distinct during the summer. Results obtained on the capacity of Cupriavidus to degrade DCAA only at 18°C but not at 10°C indicate that water temperature is a major element affecting DCAA degradation and confirming observations made regarding season influence on HAA degradation in the drinking water distribution network. This is the first demonstration of the HAA biodegradation capacity of the genus Cupriavidus. © 2013 The Society for Applied Microbiology.

  3. Abiotic degradation rates for carbon tetrachloride and chloroform: Final report.

    Energy Technology Data Exchange (ETDEWEB)

    Amonette, James E.; Jeffers, Peter M.; Qafoku, Odeta; Russell, Colleen K.; Humphrys, Daniel R.; Wietsma, Thomas W.; Truex, Michael J.

    2012-12-01

    This report documents the objectives, technical approach, and progress made through FY 2012 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater for carbon tetrachloride (CT) and chloroform (CF). The project also sought to explore the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. We conducted 114 hydrolysis rate experiments in sealed vessels across a temperature range of 20-93 °C for periods as long as 6 years, and used the Arrhenius equation to estimate activation energies and calculate half-lives for typical Hanford groundwater conditions (temperature of 16 °C and pH of 7.75). We calculated a half-life of 630 years for hydrolysis for CT under these conditions and found that CT hydrolysis was unaffected by contact with sterilized, oxidized minerals or Hanford sediment within the sensitivity of our experiments. In contrast to CT, hydrolysis of CF was generally slower and very sensitive to pH due to the presence of both neutral and base-catalyzed hydrolysis pathways. We calculated a half-life of 3400 years for hydrolysis of CF in homogeneous solution at 16 °C and pH 7.75. Experiments in suspensions of Hanford sediment or smectite, the dominant clay mineral in Hanford sediment, equilibrated to an initial pH of 7.2, yielded calculated half-lives of 1700 years and 190 years, respectively, at 16 °C. Experiments with three other mineral phases at the same pH (muscovite mica, albite feldspar, and kaolinite) showed no change from the homogeneous solution results (i.e., a half-life of 3400 years). The strong influence of Hanford sediment on CF hydrolysis was attributed to the presence of smectite and its ability to adsorb protons, thereby buffering the solution pH at a higher level than would otherwise occur. The project also determined liquid-vapor partition coefficients for CT under the temperatures and pressures encountered in the sealed vessels that

  4. Degradation rates of alachlor, atrazine and bentazone in the profiles of Polish Luvisols

    Science.gov (United States)

    Paszko, Tadeusz; Muszyński, Paweł

    2017-07-01

    The degradation rates of three herbicides (alachlor, atrazine, and bentazone) were examined according to OECD Guideline 307 in three profiles of grey-brown podzolic soil (Luvisol) in a laboratory experiment. The aim of the experiment was to determine herbicide degradation parameters and their relationships with soil properties. Degradation processes were effectively described by a first-order model. However, in some cases, the best results were produced by bi-phasic kinetics (hockey-stick and bi-exponential model). The degradation rates of the tested herbicides at 25°C and 40% maximum water holding capacity, established based on half-life values in the Ap horizon, increased in the following order: atrazine (32.6-42.8 days) < bentazone (3.4-16.6 days < alachlor (4.4-5.7 days). The correlation analysis and the Principal Component Analysis revealed significant positive correlations between the herbicide degradation rates and the organic matter content of soils. The depth-dependent degradation factors obtained for topsoil and two subsoil horizons (1: 0.42: 0.11 - based on average values, and 1: 0.31: 0.12 - based on median values) reflect the degradation abilities of Polish Luvisols. The values noted are soil-specific; therefore, they can also be applied to other pesticides in Polish Luvisols.

  5. Protein Degradation Rate in Arabidopsis thaliana Leaf Growth and Development[OPEN

    Science.gov (United States)

    Nelson, Clark J.; Castleden, Ian

    2017-01-01

    We applied 15N labeling approaches to leaves of the Arabidopsis thaliana rosette to characterize their protein degradation rate and understand its determinants. The progressive labeling of new peptides with 15N and measuring the decrease in the abundance of >60,000 existing peptides over time allowed us to define the degradation rate of 1228 proteins in vivo. We show that Arabidopsis protein half-lives vary from several hours to several months based on the exponential constant of the decay rate for each protein. This rate was calculated from the relative isotope abundance of each peptide and the fold change in protein abundance during growth. Protein complex membership and specific protein domains were found to be strong predictors of degradation rate, while N-end amino acid, hydrophobicity, or aggregation propensity of proteins were not. We discovered rapidly degrading subunits in a variety of protein complexes in plastids and identified the set of plant proteins whose degradation rate changed in different leaves of the rosette and correlated with leaf growth rate. From this information, we have calculated the protein turnover energy costs in different leaves and their key determinants within the proteome. PMID:28138016

  6. Pressurized Hot Water Extraction of anthocyanins from red onion: A study on extraction and degradation rates.

    Science.gov (United States)

    Petersson, Erik V; Liu, Jiayin; Sjöberg, Per J R; Danielsson, Rolf; Turner, Charlotta

    2010-03-17

    Pressurized Hot Water Extraction (PHWE) is a quick, efficient and environmentally friendly technique for extractions. However, when using PHWE to extract thermally unstable analytes, extraction and degradation effects occur at the same time, and thereby compete. At first, the extraction effect dominates, but degradation effects soon take over. In this paper, extraction and degradation rates of anthocyanins from red onion were studied with experiments in a static batch reactor at 110 degrees C. A total extraction curve was calculated with data from the actual extraction and degradation curves, showing that more anthocyanins, 21-36% depending on the species, could be extracted if no degradation occurred, but then longer extraction times would be required than those needed to reach the peak level in the apparent extraction curves. The results give information about the different kinetic processes competing during an extraction procedure. Copyright 2010 Elsevier B.V. All rights reserved.

  7. Neural network analysis of varying trends in real exchange rates

    NARCIS (Netherlands)

    J.F. Kaashoek (Johan); H.K. van Dijk (Herman)

    1999-01-01

    textabstractIn this paper neural networks are fitted to the real exchange rates of seven industrialized countries. The size and topology of the used networks is found by reducing the size of the network through the use of multiple correlation coefficients, principal component analysis of residuals

  8. The effect of network degradation on speech recognition

    CSIR Research Space (South Africa)

    Joubert, G

    2005-11-01

    Full Text Available The authors describe a system, based on open-source tools, that was developed in order to study the effect of network degenerations in Voice-over-Internet-Protocol applications on speech-recognition accuracy. Sophisticated play-out algorithms...

  9. Microcystin-LR Biodegradation by Bacillus sp.: Reaction Rates and Possible Genes Involved in the Degradation

    Directory of Open Access Journals (Sweden)

    Michelline M. R. Kansole

    2016-11-01

    Full Text Available Harmful cyanobacteria blooms may deteriorate freshwater environments, leading to bad water quality that can adversely affect the health of humans, animals, and aquatic life. Many cyanobacteria can produce toxic metabolites, with Microcystin-LR (MC-LR being the most commonly detected cyanotoxin in fresh water bodies. In this study, a MC-LR degrading Bacillus sp. strain was isolated from Hulupi Lake (HLPL, Taiwan and tested for its degradability of the cyanotoxin. The results showed that the degradation of Microcystin-LR by the isolated Bacillus sp. was temperature-dependent with an optimum MC-LR removal at 37 °C and a first order degradation constant rate for 0.22 day−1. The degradation rate was also found to increase with decreasing MC-LR concentrations and increasing Bacillus sp. concentrations. Biomolecular monitoring of three types of genes (mlrA, CAAX, and GST involved in the degradation indicated that mlrA, and CAAX genes were present in the indigenous bacteria in HLPL water samples. However, for the isolated Bacillus sp. strain, only CAAX genes were detected. The absence of the mlrA gene in the isolated Bacillus sp. strain shows that the degradation of MC-LR does not necessarily follow the pathways with mlrA, and can also follow the pathways involved with CAAX type II amino-terminal protease.

  10. Meneco, a Topology-Based Gap-Filling Tool Applicable to Degraded Genome-Wide Metabolic Networks.

    Directory of Open Access Journals (Sweden)

    Sylvain Prigent

    2017-01-01

    Full Text Available Increasing amounts of sequence data are becoming available for a wide range of non-model organisms. Investigating and modelling the metabolic behaviour of those organisms is highly relevant to understand their biology and ecology. As sequences are often incomplete and poorly annotated, draft networks of their metabolism largely suffer from incompleteness. Appropriate gap-filling methods to identify and add missing reactions are therefore required to address this issue. However, current tools rely on phenotypic or taxonomic information, or are very sensitive to the stoichiometric balance of metabolic reactions, especially concerning the co-factors. This type of information is often not available or at least prone to errors for newly-explored organisms. Here we introduce Meneco, a tool dedicated to the topological gap-filling of genome-scale draft metabolic networks. Meneco reformulates gap-filling as a qualitative combinatorial optimization problem, omitting constraints raised by the stoichiometry of a metabolic network considered in other methods, and solves this problem using Answer Set Programming. Run on several artificial test sets gathering 10,800 degraded Escherichia coli networks Meneco was able to efficiently identify essential reactions missing in networks at high degradation rates, outperforming the stoichiometry-based tools in scalability. To demonstrate the utility of Meneco we applied it to two case studies. Its application to recent metabolic networks reconstructed for the brown algal model Ectocarpus siliculosus and an associated bacterium Candidatus Phaeomarinobacter ectocarpi revealed several candidate metabolic pathways for algal-bacterial interactions. Then Meneco was used to reconstruct, from transcriptomic and metabolomic data, the first metabolic network for the microalga Euglena mutabilis. These two case studies show that Meneco is a versatile tool to complete draft genome-scale metabolic networks produced from

  11. Neuronal response impedance mechanism implementing cooperative networks with low firing rates and μs precision.

    Science.gov (United States)

    Vardi, Roni; Goldental, Amir; Marmari, Hagar; Brama, Haya; Stern, Edward A; Sardi, Shira; Sabo, Pinhas; Kanter, Ido

    2015-01-01

    Realizations of low firing rates in neural networks usually require globally balanced distributions among excitatory and inhibitory links, while feasibility of temporal coding is limited by neuronal millisecond precision. We show that cooperation, governing global network features, emerges through nodal properties, as opposed to link distributions. Using in vitro and in vivo experiments we demonstrate microsecond precision of neuronal response timings under low stimulation frequencies, whereas moderate frequencies result in a chaotic neuronal phase characterized by degraded precision. Above a critical stimulation frequency, which varies among neurons, response failures were found to emerge stochastically such that the neuron functions as a low pass filter, saturating the average inter-spike-interval. This intrinsic neuronal response impedance mechanism leads to cooperation on a network level, such that firing rates are suppressed toward the lowest neuronal critical frequency simultaneously with neuronal microsecond precision. Our findings open up opportunities of controlling global features of network dynamics through few nodes with extreme properties.

  12. Mechanistic QSAR models for interpreting degradation rates of sulfonamides in UV-photocatalysis systems.

    Science.gov (United States)

    Huang, Xiangfeng; Feng, Yi; Hu, Cui; Xiao, Xiaoyu; Yu, Daliang; Zou, Xiaoming

    2015-11-01

    Photocatalysis is one of the most effective methods for treating antibiotic wastewater. Thus, it is of great significance to determine the relationship between degradation rates and structural characteristics of antibiotics in photocatalysis processes. In the present study, the photocatalytic degradation characteristics of 10 sulfonamides (SAs) were studied using two photocatalytic systems composed of nanophase titanium dioxide (nTiO2) plus ultraviolet (UV) and nTiO2/activated carbon fiber (ACF) plus UV. The results indicated that the largest apparent SA degradation rate constant (Kapp) is approximately 5 times as large as that of the smallest one. Based on the degradation mechanism and the partial least squares regression (PLS) method, optimum Quantitative Structure Activity Relationship (QSAR) models were developed for the two systems. Mechanistic models indicated that the degradation rule of SAs in the TiO2 systems strongly relates to their highest occupied molecular orbital (Ehomo), the maximum values of nucleophilic attack (f(+)x), and the minimum values of the most negative partial charge on a main-chain atom (q(C)min), whereas the maximum values of OH radical attack (f(0)x) and the apparent adsorption rate constant values (kad) are key factors affecting the degradation rule of SAs in the TiO2/ACF system. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Importance sampling in rate-sharing networks

    NARCIS (Netherlands)

    Lieshout, P.; Mandjes, M.

    2008-01-01

    We consider a network supporting elastic traffic, where the service capacity is shared among the various classes according to an alpha-fair sharing policy. Assuming Poisson arrivals and exponentially distributed service requirements for each class, the dynamics of the user population may be

  14. Kinetics analysis for development of a rate constant estimation model for ultrasonic degradation reaction of methylene blue.

    Science.gov (United States)

    Kobayashi, Daisuke; Honma, Chiemi; Matsumoto, Hideyuki; Takahashi, Tomoki; Kuroda, Chiaki; Otake, Katsuto; Shono, Atsushi

    2014-07-01

    Ultrasound has been used as an advanced oxidation method for wastewater treatment. Sonochemical degradation of organic compounds in aqueous solution occurs by pyrolysis and/or reaction with hydroxyl radicals. Moreover, kinetics of sonochemical degradation has been proposed. However, the effect of ultrasonic frequency on degradation rate has not been investigated. In our previous study, a simple model for estimating the apparent degradation rate of methylene blue was proposed. In this study, sonochemical degradation of methylene blue was performed at various frequencies. Apparent degradation rate constant was evaluated assuming that sonochemical degradation of methylene blue was a first-order reaction. Specifically, we focused on effects of ultrasonic frequency and power on rate constant, and the applicability of our proposed model was demonstrated. Using this approach, maximum sonochemical degradation rate was observed at 490 kHz, which agrees with a previous investigation into the effect of frequency on the sonochemical efficiency value evaluated by KI oxidation dosimetry. Degradation rate increased with ultrasonic power at every frequency. It was also observed that threshold power must be reached for the degradation reaction to progress. The initial methylene blue concentration and the apparent degradation rate constant have a relation of an inverse proportion. Our proposed model for estimating the apparent degradation rate constant using ultrasonic power and sonochemical efficiency value can apply to this study which extended the frequency and initial concentration range. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Modeling Day-to-day Flow Dynamics on Degradable Transport Network.

    Directory of Open Access Journals (Sweden)

    Bo Gao

    Full Text Available Stochastic link capacity degradations are common phenomena in transport network which can cause travel time variations and further can affect travelers' daily route choice behaviors. This paper formulates a deterministic dynamic model, to capture the day-to-day (DTD flow evolution process in the presence of degraded link capacity degradations. The aggregated network flow dynamics are driven by travelers' study of uncertain travel time and their choice of risky routes. This paper applies the exponential-smoothing filter to describe travelers' study of travel time variations, and meanwhile formulates risk attitude parameter updating equation to reflect travelers' endogenous risk attitude evolution schema. In addition, this paper conducts theoretical analyses to investigate several significant mathematical characteristics implied in the proposed DTD model, including fixed point existence, uniqueness, stability and irreversibility. Numerical experiments are used to demonstrate the effectiveness of the DTD model and verify some important dynamic system properties.

  16. Signal-transduction networks and the regulation of muscle protein degradation.

    Science.gov (United States)

    Szewczyk, Nathaniel J; Jacobson, Lewis A

    2005-10-01

    Protein degradation in muscle functions in maintaining normal physiological homeostasis and adapting to new homeostatic states, and is required for muscle wasting or atrophy in various pathological states. The interplay between protein synthesis and degradation to maintain homeostasis is complex and responds to a variety of autocrine and intercellular signals from neuronal inputs, hormones, cytokines, growth factors and other regulatory molecules. The intracellular events that connect extracellular signals to the molecular control of protein degradation are incompletely understood, but likely involve interacting signal-transduction networks rather than isolated pathways. We review some examples of signal-transduction systems that regulate protein degradation, including effectors of proteolysis inducing factor (PIF), insulin and insulin-like growth factor (IGF) and their receptors, and fibroblast growth factor (FGF) and its receptors.

  17. Tunable Degradation Rate and Favorable Bioactivity of Porous Calcium Sulfate Scaffolds by Introducing Nano-Hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Jianhua Zhou

    2016-12-01

    Full Text Available The bone scaffolds should possess suitable physicochemical properties and osteogenic activities. In this study, porous calcium sulfate (CaSO4 scaffolds were fabricated successfully via selected laser sintering (SLS. Nano-hydroxyapatite (nHAp, a bioactive material with a low degradation rate, was introduced into CaSO4 scaffolds to overcome the overquick absorption. The results demonstrated that nHAp could not only control the degradation rate of scaffolds by adjusting their content, but also improve the pH environment by alleviating the acidification progress during the degradation of CaSO4 scaffolds. Moreover, the improved scaffolds were covered completely with the apatite spherulites in simulated body fluid (SBF, showing their favorable bioactivity. In addition, the compression strength and fracture toughness were distinctly enhanced, which could be ascribed to large specific area of nHAp and the corresponding stress transfer.

  18. In situ and laboratory determined first-order degradation rate constants of specific organic compounds in an aerobic aquifer

    DEFF Research Database (Denmark)

    Nielsen, P.H.; Bjerg, P.L.; Nielsen, P.

    1996-01-01

    , tetrachloroethene, phenol, o-cresol, 2,4- and 2,6-dichlorophenol, 4,6-o-dichlorocresol, and o- and p-nitrophenol in an aerobic aquifer, All aromatic hydrocarbons were degraded in ISM and LBM experiments. The phenolic hydrocarbons were ail degraded in ISM experiments, but some failed to degrade in LBM experiments...... experiments. First-order degradation rate constants for aromatic and phenolic hydrocarbons ranged between 0.01 and 0.9 day(-1). Local variations in first-order degradation rates and variations between rate constants determined by ISM and LBM were generally with in a factor of 5, but no systematic differences...

  19. Fractional rate of degradation (kd) of starch in the rumen and its ...

    African Journals Online (AJOL)

    Fractional rate of degradation (kd) of starch in the rumen and its relation to in vivo rumen and total digestibility. ... Estimates of kd for starch was obtained on 19 starch sources originating from barley, wheat, oat, maize and peas and treated in different ways both chemically and physically. The starch sources were fed in mixed ...

  20. Spatial Moment Equations for a Groundwater Plume with Degradation and Rate-Limited Sorption

    Science.gov (United States)

    In this note, we analytically derive the solution for the spatial moments of groundwater solute concentration distributions simulated by a one-dimensional model that assumes advective-dispersive transport with first-order degradation and rate-limited sorption. Sorption kinetics...

  1. Rapid estimation of glucosinolate thermal degradation rate constants in leaves of Chinese kale and broccoli (Brassica oleracea) in two seasons.

    Science.gov (United States)

    Hennig, Kristin; Verkerk, Ruud; Bonnema, Guusje; Dekker, Matthijs

    2012-08-15

    Kinetic modeling was used as a tool to quantitatively estimate glucosinolate thermal degradation rate constants. Literature shows that thermal degradation rates differ in different vegetables. Well-characterized plant material, leaves of broccoli and Chinese kale plants grown in two seasons, was used in the study. It was shown that a first-order reaction is appropriate to model glucosinolate degradation independent from the season. No difference in degradation rate constants of structurally identical glucosinolates was found between broccoli and Chinese kale leaves when grown in the same season. However, glucosinolate degradation rate constants were highly affected by the season (20-80% increase in spring compared to autumn). These results suggest that differences in glucosinolate degradation rate constants can be due to variation in environmental as well as genetic factors. Furthermore, a methodology to estimate rate constants rapidly is provided to enable the analysis of high sample numbers for future studies.

  2. Elucidating PID Degradation Mechanisms and In Situ Dark I-V Monitoring for Modeling Degradation Rate in CdTe Thin-Film Modules

    DEFF Research Database (Denmark)

    Hacke, Peter; Spataru, Sergiu; Johnston, Steve

    2016-01-01

    A progression of potential-induced degradation (PID) mechanisms are observed in CdTe modules, including shunting/junction degradation and two different manifestations of series resistance depending on the stress level and water ingress. The dark I-V method for in-situ characterization of Pmax based...... on superposition was adapted for the thin-film modules undergoing PID in view of the degradation mechanisms observed. An exponential model based on module temperature and relative humidity was fit to the PID rate for multiple stress levels in chamber tests and validated by predicting the observed degradation...... of the module type in the field....

  3. Elucidating PID Degradation Mechanisms and In Situ Dark I–V Monitoring for Modeling Degradation Rate in CdTe Thin-Film Modules

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, Peter; Spataru, Sergiu; Johnston, Steve; Terwilliger, Kent; VanSant, Kaitlyn; Kempe, Michael; Wohlgemuth, John; Kurtz, Sarah; Olsson, Anders; Propst, Michelle

    2016-11-01

    A progression of potential-induced degradation (PID) mechanisms are observed in CdTe modules, including shunting/junction degradation and two different manifestations of series resistance depending on the stress level and water ingress. The dark I-V method for in-situ characterization of Pmax based on superposition was adapted for the thin-film modules undergoing PID in view of the degradation mechanisms observed. An exponential model based on module temperature and relative humidity was fit to the PID rate for multiple stress levels in chamber tests and validated by predicting the observed degradation of the module type in the field.

  4. Bearing performance degradation assessment based on time-frequency code features and SOM network

    Science.gov (United States)

    Zhang, Yan; Tang, Baoping; Han, Yan; Deng, Lei

    2017-04-01

    Bearing performance degradation assessment and prognostics are extremely important in supporting maintenance decision and guaranteeing the system’s reliability. To achieve this goal, this paper proposes a novel feature extraction method for the degradation assessment and prognostics of bearings. Features of time-frequency codes (TFCs) are extracted from the time-frequency distribution using a hybrid procedure based on short-time Fourier transform (STFT) and non-negative matrix factorization (NMF) theory. An alternative way to design the health indicator is investigated by quantifying the similarity between feature vectors using a self-organizing map (SOM) network. On the basis of this idea, a new health indicator called time-frequency code quantification error (TFCQE) is proposed to assess the performance degradation of the bearing. This indicator is constructed based on the bearing real-time behavior and the SOM model that is previously trained with only the TFC vectors under the normal condition. Vibration signals collected from the bearing run-to-failure tests are used to validate the developed method. The comparison results demonstrate the superiority of the proposed TFCQE indicator over many other traditional features in terms of feature quality metrics, incipient degradation identification and achieving accurate prediction. Highlights • Time-frequency codes are extracted to reflect the signals’ characteristics. • SOM network served as a tool to quantify the similarity between feature vectors. • A new health indicator is proposed to demonstrate the whole stage of degradation development. • The method is useful for extracting the degradation features and detecting the incipient degradation. • The superiority of the proposed method is verified using experimental data.

  5. Information mining in weighted complex networks with nonlinear rating projection

    Science.gov (United States)

    Liao, Hao; Zeng, An; Zhou, Mingyang; Mao, Rui; Wang, Bing-Hong

    2017-10-01

    Weighted rating networks are commonly used by e-commerce providers nowadays. In order to generate an objective ranking of online items' quality according to users' ratings, many sophisticated algorithms have been proposed in the complex networks domain. In this paper, instead of proposing new algorithms we focus on a more fundamental problem: the nonlinear rating projection. The basic idea is that even though the rating values given by users are linearly separated, the real preference of users to items between the different given values is nonlinear. We thus design an approach to project the original ratings of users to more representative values. This approach can be regarded as a data pretreatment method. Simulation in both artificial and real networks shows that the performance of the ranking algorithms can be improved when the projected ratings are used.

  6. Generalized groundwater plume with degradation and rate-limited sorption model with Mittag-Leffler law

    Directory of Open Access Journals (Sweden)

    Badr Saad T. Alkahtani

    Full Text Available The concept of differentiation with the generalized Mittag-Leffler law is used in this paper to construct the model of movement of groundwater pollution with degradation and limited sorption. The fractional differentiation used in the model is in Riemann-Liouville sense. The new model is solved analytically using the Green Laplace transform approach. A numerical scheme is used to obtain the numerical solution of the modified model. Keywords: Movement of groundwater pollution, Plume with degradation, Rate-limited sorption, Atangana-Baleanu derivative in Riemann-Liouville sense

  7. Single molecule approaches for quantifying transcription and degradation rates in intact mammalian tissues.

    Science.gov (United States)

    Bahar Halpern, Keren; Itzkovitz, Shalev

    2016-04-01

    A key challenge in mammalian biology is to understand how rates of transcription and mRNA degradation jointly shape cellular gene expression. Powerful techniques have been developed for measuring these rates either genome-wide or at the single-molecule level, however these techniques are not applicable to assessment of cells within their native tissue microenvironment. Here we describe a technique based on single molecule Fluorescence in-situ Hybridization (smFISH) to measure transcription and degradation rates in intact mammalian tissues. The technique is based on dual-color libraries targeting the introns and exons of the genes of interest, enabling visualization and quantification of both nascent and mature mRNA. We present a software, TransQuant, that facilitates quantifying these rates from smFISH images. Our approach enables assessment of both transcription and degradation rates of any gene of interest while controlling for the inherent heterogeneity of intact tissues. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Dose rate effects in radiation degradation of polymer-based cable materials

    Energy Technology Data Exchange (ETDEWEB)

    Placek, V. E-mail: pla@ujv.cz; Bartonicek, B.; Hnat, V.; Otahal, B

    2003-08-01

    Cable ageing under the nuclear power plant (NPP) conditions must be effectively managed to ensure that the required plant safety and reliability are maintained throughout the plant service life. Ionizing radiation is one of the main stressors causing age-related degradation of polymer-based cable materials in air. For a given absorbed dose, radiation-induced damage to a polymer in air environment usually depends on the dose rate of the exposure. In this work, the effect of dose rate on the degradation rate has been studied. Three types of NPP cables (with jacket/insulation combinations PVC/PVC, PVC/PE, XPE/XPE) were irradiated at room temperature using {sup 60}Co gamma ray source at average dose rates of 7, 30 and 100 Gy/h with the doses up to 590 kGy. The irradiated samples have been tested for their mechanical properties, thermo-oxidative stability (using differential scanning calorimetry, DSC), and density. In the case of PVC and PE samples, the tested properties have shown evident dose rate effects, while the XPE material has shown no noticeable ones. The values of elongation at break and the thermo-oxidative stability decrease with the advanced degradation, density tends to increase with the absorbed dose. For XPE samples this effect can be partially explained by the increase of crystallinity. It was tested by the DSC determination of the crystalline phase amount.

  9. On the degelation of networks - Case of the radiochemical degradation of methyl methacrylate - ethylene glycol dimethacrylate copolymers

    Science.gov (United States)

    Richaud, Emmanuel; Gilormini, Pierre; Verdu, Jacques

    2016-05-01

    Methyl methacrylate networks were synthetized and submitted to radiochemical degradation. Ageing was monitored by means of sol-gel analysis and glass transition temperature measurements. Networks were shown to undergo exclusively chain scission process leading to the degelation of network. The critical conversion degree corresponding to degelation (loss of all elastically active chains) is discussed regarding a statistical theory.

  10. On the degelation of networks – Case of the radiochemical degradation of methyl methacrylate – ethylene glycol dimethacrylate copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Richaud, Emmanuel; Gilormini, Pierre; Verdu, Jacques [Arts et Métiers ParisTech, CNRS, PIMM UMR 8006, 151 bd de l’Hôpital, 75013 Paris (France)

    2016-05-18

    Methyl methacrylate networks were synthetized and submitted to radiochemical degradation. Ageing was monitored by means of sol-gel analysis and glass transition temperature measurements. Networks were shown to undergo exclusively chain scission process leading to the degelation of network. The critical conversion degree corresponding to degelation (loss of all elastically active chains) is discussed regarding a statistical theory.

  11. Algorithm for queueing networks with multi-rate traffic

    DEFF Research Database (Denmark)

    Iversen, Villy Bæk; King-Tim, Ko

    2011-01-01

    In this paper we present a new algorithm for evaluating queueing networks with multi-rate traffic. The detailed state space of a node is evaluated by explicit formulæ. We consider reversible nodes with multi-rate traffic and find the state probabilities by taking advantage of local balance. Theory...... is reversibility which implies that the arrival process and departure process are identical processes, for example state-dependent Poisson processes. This property is equivalent to reversibility. Due to product form, an open network with multi-rate traffic is easy to evaluate by convolution algorithms because...

  12. A reconsideration of negative ratings for network-based recommendation

    Science.gov (United States)

    Hu, Liang; Ren, Liang; Lin, Wenbin

    2018-01-01

    Recommendation algorithms based on bipartite networks have become increasingly popular, thanks to their accuracy and flexibility. Currently, many of these methods ignore users' negative ratings. In this work, we propose a method to exploit negative ratings for the network-based inference algorithm. We find that negative ratings play a positive role regardless of sparsity of data sets. Furthermore, we improve the efficiency of our method and compare it with the state-of-the-art algorithms. Experimental results show that the present method outperforms the existing algorithms.

  13. Algorithm for queueing networks with multi-rate traffic

    DEFF Research Database (Denmark)

    Iversen, Villy Bæk; Ko, King-Tim

    2011-01-01

    In this paper we present a new algorithm for evaluating queueing networks with multi-rate traffic. The detailed state space of a node is evaluated by explicit formulæ. We consider reversible nodes with multi-rate traffic and find the state probabilities by taking advantage of local balance. Theory...... is reversibility which implies that the arrival process and departure process are identical processes, for example state-dependent Poisson processes. This property is equivalent to reversibility. Due to product form, an open network with multi-rate traffic is easy to evaluate by convolution algorithms because...... the nodes behave as independent nodes. For closed queueing networks with multiple servers in every node and multi-rate services we may apply multidimensional convolution algorithm to aggregate the nodes so that we end up with two nodes, the aggregated node and a single node, for which we can calculate...

  14. Benthic life in the pelagic: Aggregate encounter and degradation rates by pelagic harpacticoid copepods

    DEFF Research Database (Denmark)

    Koski, Marja; Kiørboe, Thomas; Takahashi, K.

    2005-01-01

    We measured field abundances, feeding rates, swimming behavior, and particle colonization of two harpacticoids, the pelagic Microsetella norvegica and the semibenthic Amonardia normanni, to examine (1) if aggregates have a significant role in harpacticoid nutrition and (2) if harpacticoids...... contribute significantly to aggregate degradation. Neither of the harpacticoids was able to feed efficiently on suspended food, while both grazed well on attached food, indicating that pelagic harpacticoids depend on food attached to surfaces, such as those offered by marine aggregates. We estimated...

  15. Bacterial secondary production on vascular plant detritus: relationships to detritus composition and degradation rate.

    Science.gov (United States)

    Moran, M A; Hodson, R E

    1989-01-01

    Bacterial production at the expense of vascular plant detritus was measured for three emergent plant species (Juncus effusus, Panicum hemitomon, and Typha latifolia) degrading in the littoral zone of a thermally impacted lake. Bacterial secondary production, measured as tritiated thymidine incorporation into DNA, ranged from 0.01 to 0.81 microgram of bacterial C mg of detritus-1 day-1. The three plant species differed with respect to the amount of bacterial productivity they supported per milligram of detritus, in accordance with the predicted biodegradability of the plant material based on initial nitrogen content, lignin content, and C/N ratio. Bacterial production also varied throughout the 22 weeks of in situ decomposition and was positively related to the nitrogen content and lignin content of the remaining detritus, as well as to the temperature of the lake water. Over time, production was negatively related to the C/N ratio and cellulose content of the degrading plant material. Bacterial production on degrading plant material was also calculated on the basis of plant surface area and ranged from 0.17 to 1.98 micrograms of bacterial C cm-2 day-1. Surface area-based calculations did not correlate well with either initial plant composition or changing composition of the remaining detritus during decomposition. The rate of bacterial detritus degradation, calculated from measured production of surface-attached bacteria, was much lower than the actual rate of weight loss of plant material. This discrepancy may be attributable to the importance of nonbacterial organisms in the degradation and loss of plant material from litterbags or to the microbially mediated solubilization of particulate material prior to bacterial utilization, or both. PMID:2802603

  16. A new approach to estimate the in situ fractional degradation rate of organic matter and nitrogen in wheat yeast concentrates

    NARCIS (Netherlands)

    De Jonge, L. H.; Van Laar, H.; Hendriks, W. H.; Dijkstra, J.

    2015-01-01

    In the classic in situ method, small particles are removed during rinsing and hence their fractional degradation rate cannot be determined. A new approach was developed to estimate the fractional degradation rate of nutrients in small particles. This approach was based on an alternative rinsing

  17. Poly(amido-amine)-based hydrogels with tailored mechanical properties and degradation rates for tissue engineering.

    Science.gov (United States)

    Martello, Federico; Tocchio, Alessandro; Tamplenizza, Margherita; Gerges, Irini; Pistis, Valentina; Recenti, Rossella; Bortolin, Monica; Del Fabbro, Massimo; Argentiere, Simona; Milani, Paolo; Lenardi, Cristina

    2014-03-01

    Poly(amido-amine) (PAA) hydrogels containing the 2,2-bisacrylamidoacetic acid-4-amminobutyl guanidine monomeric unit have a known ability to enhance cellular adhesion by interacting with the arginin-glycin-aspartic acid (RGD)-binding αVβ3 integrin, expressed by a wide number of cell types. Scientific interest in this class of materials has traditionally been hampered by their poor mechanical properties and restricted range of degradation rate. Here we present the design of novel biocompatible, RGD-mimic PAA-based hydrogels with wide and tunable degradation rates as well as improved mechanical and biological properties for biomedical applications. This is achieved by radical polymerization of acrylamide-terminated PAA oligomers in both the presence and absence of 2-hydroxyethylmethacrylate. The degradation rate is found to be precisely tunable by adjusting the PAA oligomer molecular weight and acrylic co-monomer concentration in the starting reaction mixture. Cell adhesion and proliferation tests on Madin-Darby canine kidney epithelial cells show that PAA-based hydrogels have the capacity to promote cell adhesion up to 200% compared to the control. Mechanical tests show higher compressive strength of acrylic chain containing hydrogels compared to traditional PAA hydrogels. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  18. Effect of hydrion evolution by polylactic-co-glycolic acid coating on degradation rate of pure iron.

    Science.gov (United States)

    Wu, Jingyao; Lu, Xi; Tan, Lili; Zhang, Bingchun; Yang, Ke

    2013-10-01

    For biodegradable iron coronary stents, the major problem is the low degradation rate in body environment. In this study, a new strategy was proposed to increase the degradation rate of iron in vitro. The hydrion evolution was intended to be introduced into the degradation system to increase the degradation rate. To realize this strategy, polylactic-co-glycolic acid (PLGA) was coated onto the surface of pure iron. The degradation process and mechanism of pure iron coated with PLGA were investigated. The results showed that iron coated with PLGA exhibited higher degradation rate in the static immersion test all along. With the degradation of PLGA, the oligomers of PLGA could release abundant H(+) which could dissolve the ferrous oxide to make the electrolyte and oxygen to reach the surface of iron again and simultaneity trigger the hydrion evolution at the middle stage of the degradation. The study also revealed that the solution ions failed to permeate the PLGA coating and the deposition of calcium and phosphorus in the degradation layer was inhibited which further enhanced the degradation. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

  19. Estimation of blood flow rates in large microvascular networks.

    Science.gov (United States)

    Fry, Brendan C; Lee, Jack; Smith, Nicolas P; Secomb, Timothy W

    2012-08-01

    Recent methods for imaging microvascular structures provide geometrical data on networks containing thousands of segments. Prediction of functional properties, such as solute transport, requires information on blood flow rates also, but experimental measurement of many individual flows is difficult. Here, a method is presented for estimating flow rates in a microvascular network based on incomplete information on the flows in the boundary segments that feed and drain the network. With incomplete boundary data, the equations governing blood flow form an underdetermined linear system. An algorithm was developed that uses independent information about the distribution of wall shear stresses and pressures in microvessels to resolve this indeterminacy, by minimizing the deviation of pressures and wall shear stresses from target values. The algorithm was tested using previously obtained experimental flow data from four microvascular networks in the rat mesentery. With two or three prescribed boundary conditions, predicted flows showed relatively small errors in most segments and fewer than 10% incorrect flow directions on average. The proposed method can be used to estimate flow rates in microvascular networks, based on incomplete boundary data, and provides a basis for deducing functional properties of microvessel networks. © 2012 John Wiley & Sons Ltd.

  20. Firing rate dynamics in recurrent spiking neural networks with intrinsic and network heterogeneity.

    Science.gov (United States)

    Ly, Cheng

    2015-12-01

    Heterogeneity of neural attributes has recently gained a lot of attention and is increasing recognized as a crucial feature in neural processing. Despite its importance, this physiological feature has traditionally been neglected in theoretical studies of cortical neural networks. Thus, there is still a lot unknown about the consequences of cellular and circuit heterogeneity in spiking neural networks. In particular, combining network or synaptic heterogeneity and intrinsic heterogeneity has yet to be considered systematically despite the fact that both are known to exist and likely have significant roles in neural network dynamics. In a canonical recurrent spiking neural network model, we study how these two forms of heterogeneity lead to different distributions of excitatory firing rates. To analytically characterize how these types of heterogeneities affect the network, we employ a dimension reduction method that relies on a combination of Monte Carlo simulations and probability density function equations. We find that the relationship between intrinsic and network heterogeneity has a strong effect on the overall level of heterogeneity of the firing rates. Specifically, this relationship can lead to amplification or attenuation of firing rate heterogeneity, and these effects depend on whether the recurrent network is firing asynchronously or rhythmically firing. These observations are captured with the aforementioned reduction method, and furthermore simpler analytic descriptions based on this dimension reduction method are developed. The final analytic descriptions provide compact and descriptive formulas for how the relationship between intrinsic and network heterogeneity determines the firing rate heterogeneity dynamics in various settings.

  1. Semi-Degradable Poly(β-amino ester) Networks with Temporally-Controlled Enhancement of Mechanical Properties

    Science.gov (United States)

    Safranski, David L.; Weiss, Daiana; Clark, J. Brian; Taylor, W.R.; Gall, Ken

    2014-01-01

    Biodegradable polymers are clinically used in numerous biomedical applications, and classically show a loss in mechanical properties within weeks of implantation. This work demonstrates a new class of semi-degradable polymers that show an increase in mechanical properties through degradation via a controlled shift in a thermal transition. Semi-degradable polymer networks, poly(β-amino ester)-co-methyl methacrylate, were formed from a low glass transition temperature crosslinker, poly(β-amino ester), and high glass transition temperature monomer, methyl methacrylate, which degraded in a manner dependent upon the crosslinker chemical structure. In vitro and in vivo degradation revealed changes in mechanical behavior due to the degradation of the crosslinker from the polymer network. This novel polymer system demonstrates a strategy to temporally control the mechanical behavior of polymers and to enhance the initial performance of smart biomedical devices. PMID:24769113

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

    Science.gov (United States)

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

    2016-08-15

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

  3. When do correlations increase with firing rates in recurrent networks?

    Directory of Open Access Journals (Sweden)

    Andrea K Barreiro

    2017-04-01

    Full Text Available A central question in neuroscience is to understand how noisy firing patterns are used to transmit information. Because neural spiking is noisy, spiking patterns are often quantified via pairwise correlations, or the probability that two cells will spike coincidentally, above and beyond their baseline firing rate. One observation frequently made in experiments, is that correlations can increase systematically with firing rate. Theoretical studies have determined that stimulus-dependent correlations that increase with firing rate can have beneficial effects on information coding; however, we still have an incomplete understanding of what circuit mechanisms do, or do not, produce this correlation-firing rate relationship. Here, we studied the relationship between pairwise correlations and firing rates in recurrently coupled excitatory-inhibitory spiking networks with conductance-based synapses. We found that with stronger excitatory coupling, a positive relationship emerged between pairwise correlations and firing rates. To explain these findings, we used linear response theory to predict the full correlation matrix and to decompose correlations in terms of graph motifs. We then used this decomposition to explain why covariation of correlations with firing rate-a relationship previously explained in feedforward networks driven by correlated input-emerges in some recurrent networks but not in others. Furthermore, when correlations covary with firing rate, this relationship is reflected in low-rank structure in the correlation matrix.

  4. Network Degradation Effects on Different Codec Types and Characteristics of Video Streaming

    Directory of Open Access Journals (Sweden)

    Jaroslav Frnda

    2014-01-01

    Full Text Available Nowadays, there is a quickly growing demand for the transmission of voice, video and data over an IP based network. Multimedia, whether we are talking about broadcast, audio and video transmission and others, from a global perspective is growing exponentially with time. With incoming requests from users, new technologies for data transfer are continually developing. Data must be delivered reliably and with the fewest losses at such high speed. Video quality as part of multimedia technology has a very important role nowadays. It is influenced by several factors, where each of them can have many forms and processing. Network performance is the major degradation effect that influences the quality of resulting image. Poor network performance (lack of link capacity, high network load… causes data packet losses or different delivery time for each packet. This work focuses exactly on these network phenomena. It examines the impact of different delays and packet losses on the quality parameters of triple play services, to evaluate the results using objective methods. The aim of this work is to bring a detailed view on the performance of video streaming over IP-based networks.

  5. Neural Networks Modelling of Municipal Real Estate Market Rent Rates

    Directory of Open Access Journals (Sweden)

    Muczyński Andrzej

    2016-12-01

    Full Text Available This paper presents the results of research on the application of neural networks modelling of municipal real estate market rent rates. The test procedure was based on selected networks trained on the local real estate market data and transformation of the detected dependencies – through established models – to estimate the potential market rent rates of municipal premises. On this basis, the assessment of the adequacy of the actual market rent rates of municipal properties was made. Empirical research was conducted on the local real estate market of the city of Olsztyn in Poland. In order to describe the phenomenon of market rent rates formation an unidirectional three-layer network and a network of radial base was selected. Analyses showed a relatively low degree of convergence of the actual municipal rent rents with potential market rent rates. This degree was strongly varied depending on the type of business ran on the property and its’ social and economic impact. The applied research methodology and the obtained results can be used in order to rationalize municipal property management, including the activation of rental policy.

  6. Degradation rates of phorbol esters in Jatropha curcas L. oil and pressed seeds under different storage conditions.

    Science.gov (United States)

    Phasukarratchai, Naphatsarnan; Damrongsiri, Seelawut; Tongcumpou, Chantra

    2017-03-01

    Phorbol esters (PEs), found in Jatropha curcas crude oil (JCO) and J. curcas pressed seeds (JPS), are known as bioactive compounds in agricultural and pharmaceutical applications. The degradation rates of PEs in JCO and JPS under various conditions is important for the utilisation of PEs. Thus the objective of this study was to determine the PE degradation rates in JCO and JPS under different storage conditions. PE degradation rates were found to be first-order reactions. The slowest degradation rate was at 0.9 × 10 -3 d -1 for both JCO and JPS unexposed to light at 4 °C. Light intensity (1097 lx and 4690 lx, representing diffused sunlight and fluorescent lighting, respectively) and temperature (25 to 35 °C) were the significant degradation factors. Light exposure led to 280% to 380% higher degradation rates in JCO than in JPS due to light penetration through the transparent oil. Dried and sterilised JPS showed an 80% to 90% lower PE degradation rate than untreated JPS under all storage conditions since biodegradation was assembly limited. The PEs were unstable under the studied conditions, especially when exposed to light and room temperature. To protect against PE degradation, a material should be stored in a light-protected container and below 4 °C. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  7. Reaction mechanisms and rate constants of waste degradation in landfill bioreactor systems with enzymatic-enhancement.

    Science.gov (United States)

    Jayasinghe, P A; Hettiaratchi, J P A; Mehrotra, A K; Kumar, S

    2014-06-01

    Augmenting leachate before recirculation with peroxidase enzymes is a novel method to increase the available carbon, and therefore the food supply to microorganisms at the declining phase of the anaerobic landfill bioreactor operation. In order to optimize the enzyme-catalyzed leachate recirculation process, it is necessary to identify the reaction mechanisms and determine rate constants. This paper presents a kinetic model developed to ascertain the reaction mechanisms and determine the rate constants for enzyme catalyzed anaerobic waste degradation. The maximum rate of reaction (Vmax) for MnP enzyme-catalyzed reactors was 0.076 g(TOC)/g(DS).day. The catalytic turnover number (k(cat)) of the MnP enzyme-catalyzed was 506.7 per day while the rate constant (k) of the un-catalyzed reaction was 0.012 per day. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Degradation and annealing studies on gamma rays irradiated COTS PPD CISs at different dose rates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zujun, E-mail: wangzujun@nint.ac.cn [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an (China); Ma, Yingwu [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an (China); Liu, Jing [School of Materials Science and Engineering, Xiangtan University, Xiangtan, 411105 Hunan (China); Xue, Yuan; He, Baoping; Yao, Zhibin; Huang, Shaoyan; Liu, Minbo; Sheng, Jiangkun [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an (China)

    2016-06-01

    The degradation and annealing studies on Colbalt-60 gamma-rays irradiated commercial-off-the-shelf (COTS) pinned photodiode (PPD) CMOS image sensors (CISs) at the various dose rates are presented. The irradiation experiments of COTS PPD CISs are carried out at 0.3, 3.0 and 30.0 rad(Si)/s. The COTS PPD CISs are manufactured using a standard 0.18-μm CMOS technology with four-transistor pixel PPD architecture. The behavior of the tested CISs shows a remarkable degradation after irradiation and differs in the dose rates. The dark current, dark signal non-uniformity (DSNU), random noise, saturation output, signal to noise ratio (SNR), and dynamic range (DR) versus the total ionizing dose (TID) at the various dose rates are investigated. The tendency of dark current, DSNU, and random noise increase and saturation output, SNR, and DR to decrease at 3.0 rad(Si)/s are far greater than those at 0.3 and 30.0 rad(Si)/s. The damage mechanisms caused by TID irradiation at the various dose rates are also analyzed. The annealing tests are carried out at room temperature with unbiased conditions after irradiation.

  9. Balancing sample accumulation and DNA degradation rates to optimize noninvasive genetic sampling of sympatric carnivores.

    Science.gov (United States)

    Lonsinger, Robert C; Gese, Eric M; Dempsey, Steven J; Kluever, Bryan M; Johnson, Timothy R; Waits, Lisette P

    2015-07-01

    Noninvasive genetic sampling, or noninvasive DNA sampling (NDS), can be an effective monitoring approach for elusive, wide-ranging species at low densities. However, few studies have attempted to maximize sampling efficiency. We present a model for combining sample accumulation and DNA degradation to identify the most efficient (i.e. minimal cost per successful sample) NDS temporal design for capture-recapture analyses. We use scat accumulation and faecal DNA degradation rates for two sympatric carnivores, kit fox (Vulpes macrotis) and coyote (Canis latrans) across two seasons (summer and winter) in Utah, USA, to demonstrate implementation of this approach. We estimated scat accumulation rates by clearing and surveying transects for scats. We evaluated mitochondrial (mtDNA) and nuclear (nDNA) DNA amplification success for faecal DNA samples under natural field conditions for 20 fresh scats/species/season from <1-112 days. Mean accumulation rates were nearly three times greater for coyotes (0.076 scats/km/day) than foxes (0.029 scats/km/day) across seasons. Across species and seasons, mtDNA amplification success was ≥95% through day 21. Fox nDNA amplification success was ≥70% through day 21 across seasons. Coyote nDNA success was ≥70% through day 21 in winter, but declined to <50% by day 7 in summer. We identified a common temporal sampling frame of approximately 14 days that allowed species to be monitored simultaneously, further reducing time, survey effort and costs. Our results suggest that when conducting repeated surveys for capture-recapture analyses, overall cost-efficiency for NDS may be improved with a temporal design that balances field and laboratory costs along with deposition and degradation rates. © 2014 John Wiley & Sons Ltd.

  10. Artificial neural networks in analysis of indinavir and its degradation products retention.

    Science.gov (United States)

    Jancić-Stojanović, B; Ivanović, D; Malenović, A; Medenica, M

    2009-04-15

    Artificial neural networks (ANN) are biologically inspired computer programs designed to simulate the way in which the human brain processes the information. In the past few years, coupling of experimental design (ED) and ANN became useful tool in the method optimization. This paper presents the application of ED-ANN in analysis of chromatographic behavior of indinavir and its degradation products. According to preliminary study, full factorial design 2(4) was chosen to set input variables for network training. Experimental data (inputs) and results for retention factors from experiments (outputs) were used to train the ANN with aim to define correlation among variables. For networks training multi-layer perceptron (MLP) with back propagation (BP) algorithm was used. Network with the lowest root mean square (RMS) had 4-8-3 topology. Predicted data were in good agreement with experimental data (correlation was higher than 0.9713 for training set). Regression statistics confirmed good ability of trained network to predict compounds retention.

  11. Rate of hydrolysis and degradation of the cyanogenic glycoside - dhurrin - in soil

    DEFF Research Database (Denmark)

    Johansen, Henrik; Damgaard, Lars Holm; Olsen, Carl Erik

    2007-01-01

    in order to assess its fate in soil. The log Kow of dhurrin was 1.18 ± 0.08 (22 C). Hydrolysis was a first-order reaction with respect to dhurrin and hydroxyl ion concentrations. Half lives ranged from 1.2 h (pH 8.6; 25 C) to 530 d (pH 4; 25 C). The activation energy of hydrolysis was 112 + 9 kJ. At pH 5.......8 and room temperature, addition of humic acids (50 g l1) increased the rate of hydrolysis tenfold, while addition of kaolinite or goethite (100–250 g l1) both decreased the rate considerably. No significant sorption to soil components could be observed. The degradation rates of dhurrin in top and subsoils...

  12. How adaptation shapes spike rate oscillations in recurrent neuronal networks

    Directory of Open Access Journals (Sweden)

    Moritz eAugustin

    2013-02-01

    Full Text Available Neural mass signals from in-vivo recordings often show oscillations with frequencies ranging from <1 Hz to 100 Hz. Fast rhythmic activity in the beta and gamma range can be generated by network based mechanisms such as recurrent synaptic excitation-inhibition loops. Slower oscillations might instead depend on neuronal adaptation currents whose timescales range from tens of milliseconds to seconds. Here we investigate how the dynamics of such adaptation currents contribute to spike rate oscillations and resonance properties in recurrent networks of excitatory and inhibitory neurons. Based on a network of sparsely coupled spiking model neurons with two types of adaptation current and conductance based synapses with heterogeneous strengths and delays we use a mean-field approach to analyze oscillatory network activity. For constant external input, we find that spike-triggered adaptation currents provide a mechanism to generate slow oscillations over a wide range of adaptation timescales as long as recurrent synaptic excitation is sufficiently strong. Faster rhythms occur when recurrent inhibition is slower than excitation and oscillation frequency increases with the strength of inhibition. Adaptation facilitates such network based oscillations for fast synaptic inhibition and leads to decreased frequencies. For oscillatory external input, adaptation currents amplify a narrow band of frequencies and cause phase advances for low frequencies in addition to phase delays at higher frequencies. Our results therefore identify the different key roles of neuronal adaptation dynamics for rhythmogenesis and selective signal propagation in recurrent networks.

  13. A Network Centrality Method for the Rating Problem

    Science.gov (United States)

    2015-01-01

    We propose a new method for aggregating the information of multiple users rating multiple items. Our approach is based on the network relations induced between items by the rating activity of the users. Our method correlates better than the simple average with respect to the original rankings of the users, and besides, it is computationally more efficient than other methods proposed in the literature. Moreover, our method is able to discount the information that would be obtained adding to the system additional users with a systematically biased rating activity. PMID:25830502

  14. Artificial Neural Network for Monthly Rainfall Rate Prediction

    Science.gov (United States)

    Purnomo, H. D.; Hartomo, K. D.; Prasetyo, S. Y. J.

    2017-03-01

    Rainfall rate forecasting plays an important role in various human activities. Rainfall forecasting is a challenging task due to the uncertainty of natural phenomena. In this paper, two neural network models are proposed for monthly rainfall rate forecasting. The performance of the proposed model is assesses based on monthly rainfall rate in Ampel, Boyolali, from 2001-2013. The experiment results show that the accuracy of the first model is much better than the accuracy of the second model. Its average accuracy is just above 98%, while the accuracy of the second model is approximately 75%. In additional, both models tend to perform better when the fluctuation of rainfall is low.

  15. Degradation rates in thermophilic sludge processing - the liquid and the solid way

    Energy Technology Data Exchange (ETDEWEB)

    Mihaltz, P.; Kovacs, R.; Csikor, Zs.; Dahab, M.F.

    2003-07-01

    Two promising and well known techniques for sludge stabilization and pathogen destruction, the composting and autothermal thermophilic aerobic digestion (ATAD, often referred to as ''liquid composting'') have not yet undergone a comparative parallel study. This comparison is presented in this paper to identify - sometimes unusually (e.g. up to 30 mg O{sub 2} /gVS h) high - degradation rates, their main influencing parameters. For the ATAD we developed a well fitting modified two-substrate kinetic model quantitatively describing this process feature too - the clear signs of two substrate degradation also appears in most own and literature composting records. However compost process modelling needs as a prerequisite the clarification of the controlling transport mechanisms. Experimental conclusions suggest the dual role of local VS limitation closely connected with, but being behind the strong observed oxygen limitation, what is proposed for the explanation of composting process rates - essentially based on specific surface area controlled transport phenomena, justifying efforts to conduct the process at lower (<20 to 25%) moisture content and higher (>1000 1/m) specific surface area levels. (author)

  16. Review and estimation of degradation rates for concrete barriers used in low-level radioactive waste disposal

    Energy Technology Data Exchange (ETDEWEB)

    Okoshi, Minoru [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-08-01

    The processes and models of concrete degradation used as engineered barriers in low-level radioactive waste disposal were reviewed. Example calculations were performed to illustrate the degradation rates. And also, the preparation methods to make durable concrete were reviewed. In conclusion, the concrete degradation processes to be considered for the safety performance assessment for low-level radioactive waste disposal facilities are as follow : (a) reinforcement corrosion, (b) calcium hydroxide leaching, (c) sulfate attack, (d) freeze-thaw attack, and (e) alkali aggregate reaction. The models to estimate the degradation rates due to main degradation processes except for alkali aggregate reaction were developed in the USA, etc. Example calculations show that concrete barriers prepared under the good quality control and assurance will maintain the performance for more than 500 years which is the requirement for the service life of low-level radioactive waste disposal facilities in the USA. (author)

  17. Effect of Estradiol-17beta on protein synthesis and degradation rates in fused bovine satellite cell cultures.

    Science.gov (United States)

    Kamanga-Sollo, E; White, M E; Hathaway, M R; Weber, W J; Dayton, W R

    2010-07-01

    Although androgenic and estrogenic steroids are widely used to enhance muscle growth and increase feed efficiency in feedlot cattle, their mechanism of action is not well understood. Further, in vivo studies indicate that estradiol (E2) affects muscle protein synthesis and/or degradation, but in vitro results are inconsistent. We have examined the effects of E2 treatment on protein synthesis and degradation rates in fused bovine satellite cell (BSC) cultures. Additionally, to learn more about the mechanisms involved in E2-enhanced muscle growth, we have examined the effects of compounds that interfere with binding of E2 or insulin-like growth factor (IGF)-1 to their respective receptors on E2-induced alterations in protein synthesis and degradation rates in BSC cultures. Treatment of fused BSC cultures with E2 results in a concentration-dependent increase (P < 0.05) in protein synthesis rate and a decrease (P < 0.05) in protein degradation rate. The pure estrogen antagonist ICI 182 780 suppresses (P < 0.05) E2-induced alterations in protein synthesis and degradation in fused BSC cultures. The G-protein coupled receptor (GPR)-30 agonist G1 does not affect either synthesis or degradation rate, which establishes that GPR30 does not play a role in E2-induced alterations in protein synthesis or degradation. JB1, a competitive inhibitor of IGF-1 binding to the Type 1 insulin-like growth factor receptor (IGFR-1), suppresses (P < 0.05) E2-induced alterations in protein synthesis and degradation. In summary, our data show that E2 treatment directly alters both protein synthesis and degradation rates in fused BSC cultures via mechanisms involving both the classical estrogen receptor (ER) and IGFR-1.

  18. Estimating Ads’ Click through Rate with Recurrent Neural Network

    Directory of Open Access Journals (Sweden)

    Chen Qiao-Hong

    2016-01-01

    Full Text Available With the development of the Internet, online advertising spreads across every corner of the world, the ads' click through rate (CTR estimation is an important method to improve the online advertising revenue. Compared with the linear model, the nonlinear models can study much more complex relationships between a large number of nonlinear characteristics, so as to improve the accuracy of the estimation of the ads’ CTR. The recurrent neural network (RNN based on Long-Short Term Memory (LSTM is an improved model of the feedback neural network with ring structure. The model overcomes the problem of the gradient of the general RNN. Experiments show that the RNN based on LSTM exceeds the linear models, and it can effectively improve the estimation effect of the ads’ click through rate.

  19. Study on Thermal Degradation Characteristics and Regression Rate Measurement of Paraffin-Based Fuel

    Directory of Open Access Journals (Sweden)

    Songqi Hu

    2015-09-01

    Full Text Available Paraffin fuel has been found to have a regression rate that is higher than conventional HTPB (hydroxyl-terminated polybutadiene fuel and, thus, presents itself as an ideal energy source for a hybrid rocket engine. The energy characteristics of paraffin-based fuel and HTPB fuel have been calculated by the method of minimum free energy. The thermal degradation characteristics were measured for paraffin, pretreated paraffin, HTPB and paraffin-based fuel in different working conditions by the using differential scanning calorimetry (DSC and a thermogravimetric analyzer (TGA. The regression rates of paraffin-based fuel and HTPB fuel were tested by a rectangular solid-gas hybrid engine. The research findings showed that: the specific impulse of paraffin-based fuel is almost the same as that of HTPB fuel; the decomposition temperature of pretreated paraffin is higher than that of the unprocessed paraffin, but lower than that of HTPB; with the increase of paraffin, the initial reaction exothermic peak of paraffin-based fuel is reached in advance, and the initial reaction heat release also increases; the regression rate of paraffin-based fuel is higher than the common HTPB fuel under the same conditions; with the increase of oxidizer mass flow rate, the regression rate of solid fuel increases accordingly for the same fuel formulation.

  20. Abiotic Degradation Rates for Carbon Tetrachloride and Chloroform: Progress in FY 2010

    Energy Technology Data Exchange (ETDEWEB)

    Amonette, James E.; Jeffers, Peter M.; Qafoku, Odeta; Russell, Colleen K.; Humphrys, Daniel R.; Wietsma, Thomas W.; Truex, Michael J.

    2010-12-08

    This report documents the progress made through FY 2010 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater at the Hanford Site for carbon tetrachloride (CT) and chloroform (CF). The study also explores the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. The research was initiated to decrease the uncertainties in abiotic degradation rates of CT and chloroform CF associated with temperature and possible heterogeneous effects. After 2 years of data collection, the first evidence for heterogeneous effects was identified for hydrolysis of CT, and preliminary evidence for the effects of different mineral types on CF hydrolysis rates also was reported. The CT data showed no difference among mineral types, whereas significant differences were seen in the CF results, perhaps due to the fact that CF hydrolyzes by both neutral and base-catalyzed mechanisms whereas CT follows only the neutral hydrolysis path. In this report, we review the project objectives, organization, and technical approaches taken, update the status and results of the hydrolysis-rate experiments after 4 years of experimentation (i.e., through FY 2010), and provide a brief discussion of how these results add to scientific understanding of the behavior of the CT/CF plume at the Hanford Site.

  1. Bifunctional composite from spent "Cyprus coffee" for tetracycline removal and phenol degradation: Solar-Fenton process and artificial neural network.

    Science.gov (United States)

    Oladipo, Akeem Adeyemi; Abureesh, Mosab Ali; Gazi, Mustafa

    2016-09-01

    Removals of tetracycline and photocatalytic degradation of phenol by Fe3O4/coffee residue (MCC) were investigated. Brunauer-Emmett-Teller (BET), vibrating sample magnetometer (VSM) and Boehm titration were employed to characterize MCC. Artificial neural network (ANN) model was developed to predict the tetracycline (TC) concentration in the column effluent. Maximum tetracycline adsorption capacity of 285.6mg/g was observed in a batch system. High removal efficiency (87%) was obtained at 3.3mL/min flow rate, 8.0cm bed height and 50mg/L influent TC concentration in a column system. Complete degradation of phenol by solar-Fenton was attained at 60min irradiation time. Total organic carbon (TOC) removal increased to 63.3% in the presence of 1.0g/L MCC, 1.2g/L H2O2 and solar irradiation. MCC showed remarkable potential to remove antibiotics from wastewater even in the presence of heavy metal (Ni(2+)) via magnetic separation. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Coupled interference based rate adaptation in ad hoc networks

    CSIR Research Space (South Africa)

    Awuor, F

    2011-09-01

    Full Text Available since the channel condition is time variant [5], [6]. Hence CIN considers link adaptation based on SINR performance to derive transmit power that minimizes coupled interference in the network. In [5], an algorithm is proposed where an average value... channel condition variance for proper choice of PHY mode. In [7], rate adaptation scheme is proposed wherein nodes select the power-rate pair to maximize their utility based on the previous measured SINRs. The values of SINR employed by [5],[6] and [7...

  3. Degradation rates of CFC-11, CFC-12 and CFC-113 in anoxic shallow aquifers of Araihazar, Bangladesh.

    Science.gov (United States)

    Horneman, A; Stute, M; Schlosser, P; Smethie, W; Santella, N; Ho, D T; Mailloux, B; Gorman, E; Zheng, Y; van Geen, A

    2008-04-04

    Chlorofluorocarbons CFC-11 (CCl(3)F), CFC-12 (CCl(2)F(2)), and CFC-113 (CCl(2)F-CClF(2)) are used in hydrology as transient tracers under the assumption of conservative behavior in the unsaturated and saturated soil zones. However, laboratory and field studies have shown that these compounds are not stable under anaerobic conditions. To determine the degradation rates of CFCs in a tropical environment, atmospheric air, unsaturated zone soil gas, and anoxic groundwater samples were collected in Araihazar upazila, Bangladesh. Observed CFC concentrations in both soil gas and groundwater were significantly below those expected from atmospheric levels. The CFC deficits in the unsaturated zone can be explained by gas exchange with groundwater undersaturated in CFCs. The CFC deficits observed in (3)H/(3)He dated groundwater were used to estimate degradation rates in the saturated zone. The results show that CFCs are degraded to the point where practically no (CFC-11, CFC-12, or CFC-113 remains in groundwater with (3)H/(3)He ages above 10 yr. In groundwater sampled at our site CFC-11 and CFC-12 appear to degrade at similar rates with estimated degradation rates ranging from approximately 0.25 yr(-1) to approximately 6 yr(-1). Degradation rates increased as a function of reducing conditions. This indicates that CFC dating of groundwater in regions of humid tropical climate has to be carried out with great caution.

  4. Evaluation of a degradable shape-memory polymer network as matrix for controlled drug release.

    Science.gov (United States)

    Wischke, Christian; Neffe, Axel T; Steuer, Susi; Lendlein, Andreas

    2009-09-15

    Degradable shape-memory polymers are multifunctional materials with broad applicability for medical devices. They are designed to acquire their therapeutically relevant shape and mechanical properties after implantation. In this study, the potential of a completely amorphous shape-memory polymer matrix for controlled drug release was comprehensively characterized according to a four step general strategy which provides concepts for validating multifunctional materials for pharmaceutical applications. Independent functionalities are thereby crucial for fully exploiting the potential of the materials. The copolyester urethane network was synthesized by crosslinking star-shaped tetrahydroxy telechelics of oligo[(rac-lactide)-co-glycolide] with an aliphatic diisocyanate. In step 1 of the four step characterization procedure, this material showed the thermal and mechanical properties, which are required for the shape-memory effect under physiological conditions. Shape recovery could be realized by a one-step or a multi-step methodology. In step 2, feasibility of drug loading of pre-formed shape-memory networks has been demonstrated with drugs of different hydrophobicities. The presence of drugs did not disturb the material's functionalities directly after loading (step 3) and under release conditions (step 4). A predictable release of about 90% of the payload in 80 days was observed. Overall, the synthesized amorphous polymer network showed three independent functionalities, i.e., a shape-memory effect combined with biodegradability and controlled drug release.

  5. Different Stability and Proteasome-Mediated Degradation Rate of SMN Protein Isoforms.

    Directory of Open Access Journals (Sweden)

    Denise Locatelli

    Full Text Available The key pathogenic steps leading to spinal muscular atrophy (SMA, a genetic disease characterized by selective motor neuron degeneration, are not fully clarified. The full-length SMN protein (FL-SMN, the main protein product of the disease gene SMN1, plays an established role in the cytoplasm in snRNP biogenesis ultimately leading to mRNA splicing within the nucleus. It is also involved in the mRNA axonal transport. However, to what extent the impairment of these two SMN functions contributes to SMA pathogenesis remains unknown. A shorter SMN isoform, axonal-SMN or a-SMN, with more specific axonal localization, has been discovered, but whether it might act in concert with FL-SMN in SMA pathogenesis is not known. As a first step in defining common or divergent intracellular roles of FL-SMN vs a-SMN proteins, we here characterized the turn-over of both proteins and investigated which pathway contributed to a-SMN degradation. We performed real time western blot and confocal immunofluorescence analysis in easily controllable in vitro settings. We analyzed co-transfected NSC34 and HeLa cells and cell clones stably expressing both a-SMN and FL-SMN proteins after specific blocking of transcript or protein synthesis and inhibition of known intracellular degradation pathways. Our data indicated that whereas the stability of both FL-SMN and a-SMN transcripts was comparable, the a-SMN protein was characterized by a much shorter half-life than FL-SMN. In addition, as already demonstrated for FL-SMN, the Ub/proteasome pathway played a major role in the a-SMN protein degradation. We hypothesize that the faster degradation rate of a-SMN vs FL-SMN is related to the protection provided by the protein complex in which FL-SMN is assembled. The diverse a-SMN vs FL-SMN C-terminus may dictate different protein interactions and complex formation explaining the different localization and role in the neuronal compartment, and the lower expression and stability of a-SMN.

  6. Metabolic network analysis of an adipoyl-7-ADCA-producing strain of Penicillium chrysogenum: Elucidation of adipate degradation

    DEFF Research Database (Denmark)

    Thykær, Jette; Christensen, Bjarke; Nielsen, Jens

    2002-01-01

    An adipoyl-7-ADCA-producing, recombinant strain of Penicillium chrysogenum was characterized by metabolic network analysis, with special focus on the degradation of adipate and determination of the metabolic fluxes. Degradation of the side-chain precursor, adipate, causes an undesired consumption...... of adipate in the production of 7-ADCA. Using C-13-labeled glucose and measurement of metabolite labeling patterns, it was shown that adipate was degraded by beta-oxidation to succinyl-CoA and acetyl-CoA. The labeling analysis indicated that degradation of adipate was taking place in the microbodies...... and the formed acetyl-CoA was metabolized in the glyoxylate shunt. This hypothesis was further substantiated by an enzyme assay, which showed activity of the key enzyme in the glyoxylate shunt. Flux estimations in two chemostat cultures, one with and one without adipate in the feed, revealed that degradation...

  7. On the probability of exceeding allowable leak rates through degraded steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Cizelj, L.; Sorsek, I. [Jozef Stefan Institute, Ljubljana (Slovenia); Riesch-Oppermann, H. [Forschungszentrum Karlsruhe (Germany)

    1997-02-01

    This paper discusses some possible ways of predicting the behavior of the total leak rate through the damaged steam generator tubes. This failure mode is of special concern in cases where most through-wall defects may remain In operation. A particular example is the application of alternate (bobbin coil voltage) plugging criterion to Outside Diameter Stress Corrosion Cracking at the tube support plate intersections. It is the authors aim to discuss some possible modeling options that could be applied to solve the problem formulated as: Estimate the probability that the sum of all individual leak rates through degraded tubes exceeds the predefined acceptable value. The probabilistic approach is of course aiming at reliable and computationaly bearable estimate of the failure probability. A closed form solution is given for a special case of exponentially distributed individual leak rates. Also, some possibilities for the use of computationaly efficient First and Second Order Reliability Methods (FORM and SORM) are discussed. The first numerical example compares the results of approximate methods with closed form results. SORM in particular shows acceptable agreement. The second numerical example considers a realistic case of NPP in Krsko, Slovenia.

  8. Backtracking and Mixing Rate of Diffusion on Uncorrelated Temporal Networks

    Directory of Open Access Journals (Sweden)

    Martin Gueuning

    2017-10-01

    Full Text Available We consider the problem of diffusion on temporal networks, where the dynamics of each edge is modelled by an independent renewal process. Despite the apparent simplicity of the model, the trajectories of a random walker exhibit non-trivial properties. Here, we quantify the walker’s tendency to backtrack at each step (return where he/she comes from, as well as the resulting effect on the mixing rate of the process. As we show through empirical data, non-Poisson dynamics may significantly slow down diffusion due to backtracking, by a mechanism intrinsically different from the standard bus paradox and related temporal mechanisms. We conclude by discussing the implications of our work for the interpretation of results generated by null models of temporal networks.

  9. Contribution to the Artifical Neural Network Speed Estimator in a Degraded Mode for Sensor-Less Fuzzy Direct Control of Torque Application Using Dual Stars Induction Machine

    National Research Council Canada - National Science Library

    Hechelef Mohammed; Abdelkader Meroufel

    2015-01-01

    ... network accordingly, both strategies can manage the degraded and normal modes. The neural networks used are the back-propagation, to reduce the training patterns and increase the execution speed of the training...

  10. Neural Network Analysis and Evaluation of the Fetal Heart Rate

    Directory of Open Access Journals (Sweden)

    Yasuaki Noguchi

    2009-01-01

    Full Text Available The aim of the present study is to obtain a highly objective automatic fetal heart rate (FHR diagnosis. The neural network software was composed of three layers with the back propagation, to which 8 FHR data, including sinusoidal FHR, were input and the system was educated by the data of 20 cases with a known outcome. The output was the probability of a normal, intermediate, or pathologic outcome. The neural index studied prolonged monitoring. The neonatal states and the FHR score strongly correlated with the outcome probability. The neural index diagnosis was correct. The completed software was transferred to other computers, where the system function was correct.

  11. Simulation of heart rate variability model in a network

    Science.gov (United States)

    Cascaval, Radu C.; D'Apice, Ciro; D'Arienzo, Maria Pia

    2017-07-01

    We consider a 1-D model for the simulation of the blood flow in the cardiovascular system. As inflow condition we consider a model for the aortic valve. The opening and closing of the valve is dynamically determined by the pressure difference between the left ventricular and aortic pressures. At the outflow we impose a peripheral resistance model. To approximate the solution we use a numerical scheme based on the discontinuous Galerkin method. We also considering a variation in heart rate and terminal reflection coefficient due to monitoring of the pressure in the network.

  12. Metabolic and protein interaction sub-networks controlling the proliferation rate of cancer cells and their impact on patient survival.

    Science.gov (United States)

    Feizi, Amir; Bordel, Sergio

    2013-10-24

    Cancer cells can have a broad scope of proliferation rates. Here we aim to identify the molecular mechanisms that allow some cancer cell lines to grow up to 4 times faster than other cell lines. The correlation of gene expression profiles with the growth rate in 60 different cell lines has been analyzed using several genome-scale biological networks and new algorithms. New possible regulatory feedback loops have been suggested and the known roles of several cell cycle related transcription factors have been confirmed. Over 100 growth-correlated metabolic sub-networks have been identified, suggesting a key role of simultaneous lipid synthesis and degradation in the energy supply of the cancer cells growth. Many metabolic sub-networks involved in cell line proliferation appeared also to correlate negatively with the survival expectancy of colon cancer patients.

  13. A network centrality method for the rating problem

    CERN Document Server

    Li, Yongli; Wu, Chong

    2014-01-01

    We propose a new method for aggregating the information of multiple reviewers rating multiple products. Our approach is based on the network relations induced between products by the rating activity of the reviewers. We show that our method is algorithmically implementable even for large numbers of both products and consumers, as is the case for many online sites. Moreover, comparing it with the simple average, which is mostly used in practice, and with other methods previously proposed in the literature, it performs very well under various dimension, proving itself to be an optimal trade--off between computational efficiency, accordance with the reviewers original orderings, and robustness with respect to the inclusion of systematically biased reports.

  14. Discrete rate and variable power adaptation for underlay cognitive networks

    KAUST Repository

    Abdallah, Mohamed M.

    2010-01-01

    We consider the problem of maximizing the average spectral efficiency of a secondary link in underlay cognitive networks. In particular, we consider the network setting whereby the secondary transmitter employs discrete rate and variable power adaptation under the constraints of maximum average transmit power and maximum average interference power allowed at the primary receiver due to the existence of an interference link between the secondary transmitter and the primary receiver. We first find the optimal discrete rates assuming a predetermined partitioning of the signal-to-noise ratio (SNR) of both the secondary and interference links. We then present an iterative algorithm for finding a suboptimal partitioning of the SNR of the interference link assuming a fixed partitioning of the SNR of secondary link selected for the case where no interference link exists. Our numerical results show that the average spectral efficiency attained by using the iterative algorithm is close to that achieved by the computationally extensive exhaustive search method for the case of Rayleigh fading channels. In addition, our simulations show that selecting the optimal partitioning of the SNR of the secondary link assuming no interference link exists still achieves the maximum average spectral efficiency for the case where the average interference constraint is considered. © 2010 IEEE.

  15. Simulation and prediction of the thuringiensin abiotic degradation processes in aqueous solution by a radius basis function neural network model.

    Science.gov (United States)

    Zhou, Jingwen; Xu, Zhenghong; Chen, Shouwen

    2013-04-01

    The thuringiensin abiotic degradation processes in aqueous solution under different conditions, with a pH range of 5.0-9.0 and a temperature range of 10-40°C, were systematically investigated by an exponential decay model and a radius basis function (RBF) neural network model, respectively. The half-lives of thuringiensin calculated by the exponential decay model ranged from 2.72 d to 16.19 d under the different conditions mentioned above. Furthermore, an RBF model with accuracy of 0.1 and SPREAD value 5 was employed to model the degradation processes. The results showed that the model could simulate and predict the degradation processes well. Both the half-lives and the prediction data showed that thuringiensin was an easily degradable antibiotic, which could be an important factor in the evaluation of its safety. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. The microbial community structure in industrial biogas plants influences the degradation rate of straw and cellulose in batch tests.

    Science.gov (United States)

    Sun, Li; Liu, Tong; Müller, Bettina; Schnürer, Anna

    2016-01-01

    Materials rich in lignocellulose, such as straw, are abundant, cheap and highly interesting for biogas production. However, the complex structure of lignocellulose is difficult for microbial cellulolytic enzymes to access, limiting degradation. The rate of degradation depends on the activity of members of the microbial community, but the knowledge of this community in the biogas process is rather limited. This study, therefore, investigated the degradation rate of cellulose and straw in batch cultivation test initiated with inoculums from four co-digestion biogas plants (CD) and six wastewater treatment plants (WWTP). The results were correlated to the bacterial community by 454-pyrosequencing targeting 16S rRNA gene and by T-RFLP analysis targeting genes of glycoside hydrolase families 5 (cel5) and 48 (cel48), combined with construction of clone libraries. UniFrac principal coordinate analysis of 16S rRNA gene amplicons revealed a clustering of WWTPs, while the CDs were more separated from each other. Bacteroidetes and Firmicutes dominated the community with a comparably higher abundance of the latter in the processes operating at high ammonia levels. Sequences obtained from the cel5 and cel 48 clone libraries were also mainly related to the phyla Firmicutes and Bacteroidetes and here ammonia was a parameter with a strong impact on the cel5 community. The results from the batch cultivation showed similar degradation pattern for eight of the biogas plants, while two characterised by high ammonia level and low bacterial diversity, showed a clear lower degradation rate. Interestingly, two T-RFs from the cel5 community were positively correlated to high degradation rates of both straw and cellulose. One of the respective partial cel5 sequences shared 100 % identity to Clostridium cellulolyticum. The degradation rate of cellulose and straw varied in the batch tests dependent on the origin of the inoculum and was negatively correlated with the ammonia level. The

  17. Degradation Network Reconstruction in Uric Acid and Ammonium Amendments in Oil-Degrading Marine Microcosms Guided by Metagenomic Data

    KAUST Repository

    Bargiela, Rafael

    2015-11-24

    Biostimulation with different nitrogen sources is often regarded as a strategy of choice in combating oil spills in marine environments. Such environments are typically depleted in nitrogen, therefore limiting the balanced microbial utilization of carbon-rich petroleum constituents. It is fundamental, yet only scarcely accounted for, to analyze the catabolic consequences of application of biostimulants. Here, we examined such alterations in enrichment microcosms using sediments from chronically crude oil-contaminated marine sediment at Ancona harbor (Italy) amended with natural fertilizer, uric acid (UA), or ammonium (AMM). We applied the web-based AromaDeg resource using as query Illumina HiSeq meta-sequences (UA: 27,893 open reading frames; AMM: 32,180) to identify potential catabolic differences. A total of 45 (for UA) and 65 (AMM) gene sequences encoding key catabolic enzymes matched AromaDeg, and their participation in aromatic degradation reactions could be unambiguously suggested. Genomic signatures for the degradation of aromatics such as 2-chlorobenzoate, indole-3-acetate, biphenyl, gentisate, quinoline and phenanthrene were common for both microcosms. However, those for the degradation of orcinol, ibuprofen, phenylpropionate, homoprotocatechuate and benzene (in UA) and 4-aminobenzene-sulfonate, p-cumate, dibenzofuran and phthalate (in AMM), were selectively enriched. Experimental validation was conducted and good agreement with predictions was observed. This suggests certain discrepancies in action of these biostimulants on the genomic content of the initial microbial community for the catabolism of petroleum constituents or aromatics pollutants. In both cases, the emerging microbial communities were phylogenetically highly similar and were composed by very same proteobacterial families. However, examination of taxonomic assignments further revealed different catabolic pathway organization at the organismal level, which should be considered for designing

  18. Degradation network reconstruction in uric acid and ammonium amendments in oil-degrading marine microcosms guided by metagenomic data

    Directory of Open Access Journals (Sweden)

    Rafael eBargiela

    2015-11-01

    Full Text Available Biostimulation with different nitrogen sources is often regarded as a strategy of choice in combating oil spills in marine environments. Such environments are typically depleted in nitrogen, therefore limiting the balanced microbial utilization of carbon-rich petroleum constituents. It is fundamental, yet only scarcely accounted for, to analyse the catabolic consequences of application of biostimulants. Here, we examined such alterations in enrichment microcosms using sediments from chronically crude oil-contaminated marine sediment at Ancona harbor (Italy amended with natural fertilizer, uric acid (UA, or ammonium (AMM. We applied the web-based AromaDeg resource using as query Illumina HiSeq meta-sequences (UA: 27,893 open reading frames; AMM: 32,180 to identify potential catabolic differences. A total of 45 (for UA and 65 (AMM gene sequences encoding key catabolic enzymes matched AromaDeg, and their participation in aromatic degradation reactions could be unambiguously suggested. Genomic signatures for the degradation of aromatics such as 2-chlorobenzoate, indole-3-acetate, biphenyl, gentisate, quinoline and phenanthrene were common for both microcosms. However, those for the degradation of orcinol, ibuprofen, phenylpropionate, homoprotocatechuate and benzene (in UA and 4-aminobenzene-sulfonate, p-cumate, dibenzofuran and phthalate (in AMM, were selectively enriched. Experimental validation was conducted and good agreement with predictions was observed. This suggests certain discrepancies in action of these biostimulants on the genomic content of the initial microbial community for the catabolism of petroleum constituents or aromatics pollutants. In both cases, the emerging microbial communities were phylogenetically highly similar and were composed by very same proteobacterial families. However, examination of taxonomic assignments further revealed different catabolic pathway organization at the organismal level, which should be considered

  19. Degradation Rate of 5-Fluorouracil in Metastatic Colorectal Cancer: A New Predictive Outcome Biomarker?

    Directory of Open Access Journals (Sweden)

    Andrea Botticelli

    Full Text Available 5-FU based chemotherapy is the most common first line regimen used for metastatic colorectal cancer (mCRC. Identification of predictive markers of response to chemotherapy is a challenging approach for drug selection. The present study analyzes the predictive role of 5-FU degradation rate (5-FUDR and genetic polymorphisms (MTHFR, TSER, DPYD on survival.Genetic polymorphisms of MTHFR, TSER and DPYD, and the 5-FUDR of homogenous patients with mCRC were retrospectively studied. Genetic markers and the 5-FUDR were correlated with clinical outcome.133 patients affected by mCRC, treated with fluoropyrimidine-based chemotherapy from 2009 to 2014, were evaluated. Patients were classified into three metabolic classes, according to normal distribution of 5-FUDR in more than 1000 patients, as previously published: poor-metabolizer (PM with 5-FU-DR ≤ 0,85 ng/ml/106 cells/min (8 pts; normal metabolizer with 0,85 < 5-FU-DR < 2,2 ng/ml/106 cells/min (119 pts; ultra-rapid metabolizer (UM with 5-FU-DR ≥ 2,2 ng/ml/106 cells/min (6 pts. PM and UM groups showed a longer PFS respect to normal metabolizer group (14.5 and 11 months respectively vs 8 months; p = 0.029. A higher G3-4 toxicity rate was observed in PM and UM, respect to normal metabolizer (50% in both PM and UM vs 18%; p = 0.019. No significant associations between genes polymorphisms and outcomes or toxicities were observed.5-FUDR seems to be significantly involved in predicting survival of patients who underwent 5-FU based CHT for mCRC. Although our findings require confirmation in large prospective studies, they reinforce the concept that individual genetic variation may allow personalized selection of chemotherapy to optimize clinical outcomes.

  20. Practical Rate-Based Congestion Control for Wireless Mesh Networks

    Science.gov (United States)

    Elrakabawy, Sherif M.; Lindemann, Christoph

    We introduce an adaptive pacing scheme to overcome the drawbacks of TCP in wireless mesh networks with Internet connectivity. The pacing scheme is implemented at the wireless TCP sender as well as at the mesh gateway, and reacts according to the direction of TCP flows running across the wireless network and the Internet. TCP packets are transmitted rate-based within the TCP congestion window according to the current out-of-interference delay and the coefficient of variation of recently measured round-trip times. Opposed to the majority of previous work which builds on simulations, we implement a Linux prototype of our approach and evaluate its feasibility in a real 20-node mesh testbed. In an experimental performance study, we compare the goodput and fairness of our approach against the widely deployed TCP NewReno. Experiments show that our approach, which we denote as Mesh Adaptive Pacing (MAP), can achieve up to 150% more goodput than TCP NewReno and significantly improves fairness between competing flows. MAP is incrementally deployable since it is TCP-compatible, does not require cross-layer information from intermediate nodes along the path, and requires no modifications in the wired domain.

  1. Transmission rate allocation in multisensor target tracking over a shared network.

    Science.gov (United States)

    Ranasingha, M Chamara; Murthi, Manohar N; Premaratne, Kamal; Fan, Xingzhe

    2009-04-01

    In a multisensor target tracking application running on a shared network, at what bit rates should the sensors send their measurements to the tracking fusion center? Clearly, the sensors cannot use arbitrary rates in a shared network, and a standard network rate control algorithm may not provide rates amenable to effective target tracking. For Kalman filter-based multisensor target tracking, we derive a utility function that captures the tracking quality of service as a function of the sensor bit rates. We incorporate this utility function into a network rate resource allocation framework, deriving a distributed rate control algorithm for a shared network that is suitable for current best effort packet networks, such as the Internet. In simulation studies, the new rate control algorithm engenders significantly better tracking performance than a standard rate control method, while the ordinary data transfer flows continue to effectively operate while using their standard rate control methods.

  2. Wood source and pyrolysis temperature interact to control PyOM degradation rates

    Science.gov (United States)

    Bird, J. A.; Hatton, P. J.; Filley, T. R.; Chatterjee, S.; Auclerc, A.; Gormley, M.; Dastmalchi, K.; Stark, R. E.; Nadelhoffer, K. J.

    2015-12-01

    Surprisingly little is known about how shifts in tree species composition and increased forest fire frequency and intensity will affect one of the most stable pools of soil organic matter, i.e. the pyrogenic organic matter (PyOM or char). In a previous study, we showed that wood source and pyrolysis temperature interact to control PyOM structure and potential reactivity for two tree species common in high-latitude forests, jack pine (JP) and red maple (RM). Here, we investigate whether these differences affect PyOM turnover by examining the fates of 13C/15N-enriched JP wood and PyOM pyrolyzed at 300 (JP300) and 450 °C (JP450) and RM pyrolyzed at 450 °C (RM450). The substrates were applied 1-3 cm below the O/A interface of a well-drained Spodosol in a long-term forest fire study located at the University of Michigan Biological Station (Pellston, MI, USA). 13C-CO2effluxes from the first 996 days of decay showed a significant wood source by pyrolysis temperature interaction on PyOM field mineralisation rates, with RM450 mineralising twice faster than JP450 during the first 90 days. Increasing pyrolysis temperature substantially decreased field mineralization rates during the first 996 days, with mineralisation rates 24 and 80 times slower for JP300 and JP450 compared with JP wood. After 1 year, (i) bacterial groups were large sinks for PyOM-derived C as pyrolysis temperature increased and as substrate use efficiency decreased; (ii) potential phenol oxidase and net peroxidase activities were unaffected by the PyOM addition, although net peroxidase activities measured tended to lesser for soils amended with JP450 and RM450; and (iii) Collembola detritivores appeared less likely to be found for soils amended with JP450 and RM450. PyOM-derived C and N recoveries did not differ after 1 year; we will present 3-y recovery data. Our results suggest that the composition of angiosperms (e.g. RM) and gymnosperms (e.g. JP) in high-latitude forests is an underappreciated but

  3. The effect of microbubbles on gas-liquid mass transfer coefficient and degradation rate of COD in wastewater treatment.

    Science.gov (United States)

    Yao, Kangning; Chi, Yong; Wang, Fei; Yan, Jianhua; Ni, Mingjiang; Cen, Kefa

    2016-01-01

    A commonly used aeration device at present has the disadvantages of low mass transfer rate because the generated bubbles are several millimeters in diameter which are much bigger than microbubbles. Therefore, the effect of a microbubble on gas-liquid mass transfer and wastewater treatment process was investigated. To evaluate the effect of each bubble type, the volumetric mass transfer coefficients for microbubbles and conventional bubbles were determined. The volumetric mass transfer coefficient was 0.02905 s(-1) and 0.02191 s(-1) at a gas flow rate of 0.67 L min(-1) in tap water for microbubbles and conventional bubbles, respectively. The degradation rate of simulated municipal wastewater was also investigated, using aerobic activated sludge and ozone. Compared with the conventional bubble generator, the chemical oxygen demand (COD) removal rate was 2.04, 5.9, 3.26 times higher than those of the conventional bubble contactor at the same initial COD concentration of COD 200 mg L(-1), 400 mg L(-1), and 600 mg L(-1), while aerobic activated sludge was used. For the ozonation process, the rate of COD removal using microbubble generator was 2.38, 2.51, 2.89 times of those of the conventional bubble generator. Based on the results, the effect of initial COD concentration on the specific COD degradation rate were discussed in different systems. Thus, the results revealed that microbubbles could enhance mass transfer in wastewater treatment and be an effective method to improve the degradation of wastewater.

  4. Tailoring the degradation rates of thermally responsive hydrogels designed for soft tissue injection by varying the autocatalytic potential

    Science.gov (United States)

    Zhu, Yang; Jiang, Hongbin; Ye, Sang-Ho; Yoshizumi, Tomo; Wagner, William R.

    2015-01-01

    The ability to modulate the degradation properties of biomaterials such as thermally responsive hydrogels is desirable when exploring new therapeutic strategies that rely on the temporary presence of a placed scaffold or gel. Here we report a method of manipulating the absorption rate of a poly(N-isopropylacrylamide) ((poly(NIPAAm)) based hydrogel across a wide range (from 1 d to 5 mo) by small alterations in the composition. Relying upon the autocatalytic effect, the degradation of poly(NIPAAm-co-HEMA-co-MAPLA), (HEMA=2-hydroxyethyl methacrylate; MAPLA=methacrylate-polylactide) was greatly accelerated by adding a fourth monomer methacrylic acid (MAA) at no more than 2 mol% to obtain poly(NIPAAm-co-HEMA-co-MAPLA-co-MAA) (pNHMMj) where j reflects the MAA molar % in the reactant mixture. MAA residue introduction decreased the pH inside the hydrogels and in surrounding buffered solutions. Accelerated degradation positively correlated with MAA content in pNHMMj polymers, putatively by the accelerated cleavage of MAPLA residues to raise the transition temperature of the polymer above body temperature. Physical properties including thermal transition behavior and initial mechanical strength did not vary significantly with MAA content. A rat hindlimb injection model generally reflected the in vitro observation that higher MAA content resulted in more rapid degradation and cellular infiltration. The strategy of tuning the degradation of thermally responsive hydrogels where degradation or solubilization is determined by their polyester components might be applied to other tissue engineering and regenerative medicine applications where designed biomaterial degradation behavior is needed. PMID:25890745

  5. A metabolomics approach to identify factors influencing glucosinolate thermal degradation rates in Brassica vegetables.

    Science.gov (United States)

    Hennig, K; de Vos, R C H; Maliepaard, C; Dekker, M; Verkerk, R; Bonnema, G

    2014-07-15

    Thermal processing of Brassica vegetables can lead to substantial loss of potential health-promoting glucosinolates (GLs). The extent of thermal degradation of a specific GL varies in different vegetables, possibly due to differences in the composition of other metabolites within the plant matrices. An untargeted metabolomics approach followed by random forest regression was applied to identify metabolites associated to thermal GL degradation in a segregating Brassica oleracea population. Out of 413 metabolites, 15 were associated with the degradation of glucobrassicin, six with that of glucoraphanin and two with both GLs. Among these 23 metabolites three were identified as flavonols (one kaempferol- and two quercetin-derivatives) and two as other GLs (4-methoxyglucobrassicin, gluconasturtiin). Twenty quantitative trait loci (QTLs) for these metabolites, which were associated with glucoraphanin and glucobrassicin degradation, were identified on linkage groups C01, C07 and C09. Two flavonols mapped on linkage groups C07 and C09 and co-localise with the QTL for GL degradation determined previously. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. A Distributed Flow Rate Control Algorithm for Networked Agent System with Multiple Coding Rates to Optimize Multimedia Data Transmission

    Directory of Open Access Journals (Sweden)

    Shuai Zeng

    2013-01-01

    Full Text Available With the development of wireless technologies, mobile communication applies more and more extensively in the various walks of life. The social network of both fixed and mobile users can be seen as networked agent system. At present, kinds of devices and access network technology are widely used. Different users in this networked agent system may need different coding rates multimedia data due to their heterogeneous demand. This paper proposes a distributed flow rate control algorithm to optimize multimedia data transmission of the networked agent system with the coexisting various coding rates. In this proposed algorithm, transmission path and upload bandwidth of different coding rate data between source node, fixed and mobile nodes are appropriately arranged and controlled. On the one hand, this algorithm can provide user nodes with differentiated coding rate data and corresponding flow rate. On the other hand, it makes the different coding rate data and user nodes networked, which realizes the sharing of upload bandwidth of user nodes which require different coding rate data. The study conducts mathematical modeling on the proposed algorithm and compares the system that adopts the proposed algorithm with the existing system based on the simulation experiment and mathematical analysis. The results show that the system that adopts the proposed algorithm achieves higher upload bandwidth utilization of user nodes and lower upload bandwidth consumption of source node.

  7. Effect of synchronizing the rate of degradation of dietary energy and nitrogen release on growth performance in Brahman cattle

    Directory of Open Access Journals (Sweden)

    Virote Pattarajinda

    2006-01-01

    Full Text Available The objective of this research was to determine the effect of synchronizing the rate of degradation of dietary energy and nitrogen release on growth performance in Brahman beef cattle. Fifteen Brahman cattle, 1.5 years old, with an average initial body weight of 184.8±11.1 kg were assigned to one of three treatments according to a randomized complete block design. Dietary treatments contained 3 levels of synchrony index (0.39, 0.56 and 0.74 that were derived from laboratory chemical composition analysis and degradation kinetics using nylon bag technique. Diets were fed at the rate of 2.5% BW by separate concentrate and roughage. Average daily gain increased linearly (P<0.05 with increase levels of synchrony index in the diets. The digestibility of dry matter, organic matter and neutral detergent fiber increased linearly (P<0.01. The digestibility of acid detergent fiber increased linearly (P<0.05. Ruminal total volatile fatty acids concentration increased linearly (P<0.05 at 6 h post feeding. Higher concentration and fluctuation of ruminal ammonia nitrogen and blood urea nitrogen were observed in animals that received lower synchrony index in their diets. Rumen microbial population tended to increase with diets having higher levels of synchrony index. The results indicated that synchronized rate of dietary energy and nitrogen degradation improved ruminal fermentation and digestibility, thus this increased the growth rate in Brahman cattle fed with ricestraw- based diets.

  8. In vitro degradation rate of apatitic calcium phosphate cement with incorporated PLGA microspheres

    NARCIS (Netherlands)

    Felix Lanao, R.P.; Leeuwenburgh, S.C.G.; Wolke, J.G.C.; Jansen, J.A.

    2011-01-01

    Calcium phosphate cements (CPCs) are frequently used as bone substitute material. Despite their superior clinical handling and excellent biocompatibility, they exhibit poor degradability, which limits bone ingrowth into the implant. Microspheres were prepared from poly(d,l-lactic-co-glycolic acid)

  9. Statistical optimization and artificial neural network modeling for acridine orange dye degradation using in-situ synthesized polymer capped ZnO nanoparticles.

    Science.gov (United States)

    Dhiman, Nitesh; Markandeya; Singh, Amrita; Verma, Neeraj K; Ajaria, Nidhi; Patnaik, Satyakam

    2017-05-01

    ZnO NPs were synthesized by a prudent green chemistry approach in presence of polyacrylamide grafted guar gum polymer (pAAm-g-GG) to ensure uniform morphology, and functionality and appraised for their ability to degrade photocatalytically Acridine Orange (AO) dye. These ZnO@pAAm-g-GG NPs were thoroughly characterized by various spectroscopic, XRD and electron microscopic techniques. The relative quantity of ZnO NPs in polymeric matrix has been estimated by spectro-analytical procedure; AAS and TGA analysis. The impact of process parameters viz. NP's dose, contact time and AO dye concentration on percentage photocatalytic degradation of AO dyes were evaluated using multivariate optimizing tools, Response Surface Methodology (RSM) involving Box-Behnken Design (BBD) and Artificial Neural Network (ANN). Congruity of the BBD statistical model was implied by R2 value 0.9786 and F-value 35.48. At RSM predicted optimal condition viz. ZnO@pAAm-g-GG NP's dose of 0.2g/L, contact time of 210min and AO dye concentration 10mg/L, a maximum of 98% dye degradation was obtained. ANOVA indicated appropriateness of the model for dye degradation owing to "Prob.>F" less than 0.05 for variable parameters. We further, employed three layers feed forward ANN model for validating the BBD process parameters and suitability of our chosen model. The evaluation of Levenberg-Marquardt algorithm (ANN1) and Gradient Descent with adaptive learning rate (ANN2) model employed to scrutinize the best method and found experimental values of AO dye degradation were in close to those with predicated value of ANN 2 modeling with minimum error. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Improvement of the Measure of the Network Survival Rate and its Application to a Japanese Business Relations Network

    Science.gov (United States)

    Kawamoto, Hirokazu; Takayasu, Hideki; Takayasu, Misako

    We analyze the typical characteristics of the percolation transition of a large-scale complex network, a Japanese business relation network consisting of approximately 600,000 nodes and 4,000,000 links. By utilizing percolation characteristics, we revise the definition of network survival rate that we previously proposed. The new network survival rate has a strong correlation with the old one. The calculation cost is also much smaller and the number of trials decreases from 100,000 to 1,000. Finally, we discuss the identification of robust and fragile regions using this index.

  11. Application of Neural Networks to House Pricing and Bond Rating

    NARCIS (Netherlands)

    Daniëls, H.A.M.; Kamp, B.; Verkooijen, W.J.H.

    1997-01-01

    Feed forward neural networks receive a growing attention as a data modelling tool in economic classification problems. It is well-known that controlling the design of a neural network can be cumbersome. Inaccuracies may lead to a manifold of problems in the application such as higher errors due to

  12. Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. I. Preparation and in vitro degradation.

    Science.gov (United States)

    Fu, Qiang; Rahaman, Mohamed N; Fu, Hailuo; Liu, Xin

    2010-10-01

    Bioactive glass scaffolds with a microstructure similar to that of dry human trabecular bone but with three different compositions were evaluated for potential applications in bone repair. The preparation of the scaffolds and the effect of the glass composition on the degradation and conversion of the scaffolds to a hydroxyapatite (HA)-type material in a simulated body fluid (SBF) are reported here (Part I). The in vitro response of osteogenic cells to the scaffolds and the in vivo evaluation of the scaffolds in a rat subcutaneous implantation model are described in Part II. Scaffolds (porosity = 78-82%; pore size = 100-500 microm) were prepared using a polymer foam replication technique. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. The conversion rate of the scaffolds to HA in the SBF increased markedly with the B2O3 content of the glass. Concurrently, the pH of the SBF also increased with the B2O3 content of the scaffolds. The compressive strengths of the as-prepared scaffolds (5-11 MPa) were in the upper range of values reported for trabecular bone, but they decreased markedly with immersion time in the SBF and with increasing B2O3 content of the glass. The results show that scaffolds with a wide range of bioactivity and degradation rate can be achieved by replacing varying amounts of SiO(2) in silicate bioactive glass with B2O3. Copyright 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

  13. Assessing degradation rates of chlorinated ethylenes in column experiments with commercial iron materials used in permeable reactive barriers.

    Science.gov (United States)

    Ebert, Markus; Köber, Ralf; Parbs, Anika; Plagentz, Volkmar; Schäfer, Dirk; Dahmke, Andreas

    2006-03-15

    Multiple column experiments were performed using two commercial iron materials to evaluate the necessity and usefulness of preliminary investigations in permeable reactive barrier (PRB) design for chlorinated organics. Experiments were performed with contaminated groundwater and involved fresh iron granules or altered iron material excavated from PRBs. The determination of first-order rate coefficients by global nonlinear least-squares fittings indicated a variability in rate coefficients on 1 or 2 orders of magnitude. Geometric mean values of surface area normalized rate coefficients (in 10(-5) L m(-2) h(-1)) for fresh gray cast iron and iron sponge, respectively, are: tetrachloroethene (4.5, 2.6), trichloroethene (8.1, 3.3), cis-1,2-dichloroethene (3.1, 2.9), trans-1,2-dichloroethene (9.5, 5.3), 1,1-dichloroethene (4.0, 4.4), and vinyl chloride (1.6, 6.1). The increasing rate coefficients with decreasing grade of chlorination, which characterize degradation at iron sponge are linearly related to diffusion coefficients in water, suggesting diffusion limitation in the degradation process for this particular material, possibly due to a high inner surface. The variability in rate coefficients seems to be too high to use mean rate coefficients from published studies in the design procedure of PRBs, and variabilities cannot be related to groundwater characteristics, waterflow through the reactive cells, or secondary corrosion reactions.

  14. Evaluating the critical strain energy release rate of bioactive glass coatings on Ti6Al4V substrates after degradation.

    Science.gov (United States)

    Matinmanesh, A; Li, Y; Nouhi, A; Zalzal, P; Schemitsch, E H; Towler, M R; Papini, M

    2018-02-01

    It has been reported that the adhesion of bioactive glass coatings to Ti6Al4V reduces after degradation, however, this effect has not been quantified. This paper uses bilayer double cantilever (DCB) specimens to determine GIC and GIIC, the critical mode I and mode II strain energy release rates, respectively, of bioactive coating/Ti6Al4V substrate systems degraded to different extents. Three borate-based bioactive glass coatings with increasing amounts of incorporated SrO (0, 15 and 25mol%) were enamelled onto Ti6Al4V substrates and then immersed in de-ionized water for 2, 6 and 24h. The weight loss of each glass composition was measured and it was found that the dissolution rate significantly decreased with increasing SrO content. The extent of dissolution was consistent with the hypothesis that the compressive residual stress tends to reduce the dissolution rate of bioactive glasses. After drying, the bilayer DCB specimens were created and subjected to nearly mode I and mode II fracture tests. The toughest coating/substrate system (one composed of the glass containing 25mol% SrO) lost 80% and 85% of its GIC and GIIC, respectively, in less than 24h of degradation. The drop in GIC and GIIC occurred even more rapidly for other coating/substrate systems. Therefore, degradation of borate bioactive glass coatings is inversely related to their fracture toughness when coated onto Ti6A4V substrates. Finally, roughening the substrate was found to be inconsequential in increasing the toughness of the system as the fracture toughness was limited by the cohesive toughness of the glass itself. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Measurement of switching latency in high data rate Ethernet networks

    OpenAIRE

    Hegr, Tomáš; Vozňák, Miroslav; Kozák, Miloš; Boháč, Leoš

    2015-01-01

    The paper deals with a methodology of switching latency measurement in switched Ethernet networks. The switching latency is parameter necessary for simulation and design of low-latency networks that are often intended for realtime control inherent to many industrial applications. The proposed measurement methodology provides a simple way of switching the latency determination and vendor quoted latency values verification directly at the physical layer. Numerous experimental measurements...

  16. Decreasing-Rate Pruning Optimizes the Construction of Efficient and Robust Distributed Networks.

    Directory of Open Access Journals (Sweden)

    Saket Navlakha

    2015-07-01

    Full Text Available Robust, efficient, and low-cost networks are advantageous in both biological and engineered systems. During neural network development in the brain, synapses are massively over-produced and then pruned-back over time. This strategy is not commonly used when designing engineered networks, since adding connections that will soon be removed is considered wasteful. Here, we show that for large distributed routing networks, network function is markedly enhanced by hyper-connectivity followed by aggressive pruning and that the global rate of pruning, a developmental parameter not previously studied by experimentalists, plays a critical role in optimizing network structure. We first used high-throughput image analysis techniques to quantify the rate of pruning in the mammalian neocortex across a broad developmental time window and found that the rate is decreasing over time. Based on these results, we analyzed a model of computational routing networks and show using both theoretical analysis and simulations that decreasing rates lead to more robust and efficient networks compared to other rates. We also present an application of this strategy to improve the distributed design of airline networks. Thus, inspiration from neural network formation suggests effective ways to design distributed networks across several domains.

  17. Multiscale analysis of the radiooxidative degradation of EVA/EPDM composites. ATH filler and dose rate effect

    Science.gov (United States)

    Sidi, Ahmedou; Colombani, Juliette; Larché, Jean-François; Rivaton, Agnès

    2018-01-01

    This study is focused on the radiooxidative degradation of polymeric insulation of electric cables used in Nuclear Power Plants (NPPs). In order to investigate the degradation mechanisms of the insulation, model composites with ATH (Aluminium TriHydrate) filler and blends (without filler) based on a cross-linked mixture of EVA (Ethylene Vinyl Acetate) and EPDM (Ethylene Propylene Diene Monomer) were submitted to gamma-rays. In normal operating conditions of a NPP, the dose rate which electric cables are exposed to is around 0.1 Gy h-1. In this work, artificial accelerated ageing test process has been applied at a relatively low dose rate of 7 Gy h-1. Gamma-irradiations at higher dose rates typically used to accelerate the ageing, in the range 0.2-1 kGy h-1, were also carried out. The first part of the study is focused on irradiations performed at relatively low dose rate and is devoted to the highlighting of the radiooxidative degradation mechanisms of EVA/EPDM blend with and without ATH filler. Correlations between the evolutions of the chemical, morphological and mechanical/electrical properties of the materials occurring after the ageing process are presented. It is shown that the degradation process is governed by radical oxidation mechanism involving chain scissions leading to the formation of carboxylic acids as end-groups. One of the main effects of the ATH filler is the progressive loss of the mechanical properties of the composite upon radiooxidation whereas they are maintained in the case of the unfilled sample. Despite the oxidation of the polymer, no change in the electrical properties of the blend and of the composite could be observed. The second part of the study focuses on the dose rate effect. It is shown that one of the main consequences of an increase of the dose rate from 7 Gy h-1 to 0.2-1 kGy h-1 is a reduction of the chain scission process yield by a factor of about 20. Therefore, an important and consistent finding is that there are some

  18. A new approach to estimate the in situ fractional degradation rate of organic matter and nitrogen in wheat yeast concentrates.

    Science.gov (United States)

    de Jonge, L H; van Laar, H; Hendriks, W H; Dijkstra, J

    2015-03-01

    In the classic in situ method, small particles are removed during rinsing and hence their fractional degradation rate cannot be determined. A new approach was developed to estimate the fractional degradation rate of nutrients in small particles. This approach was based on an alternative rinsing method to reduce the particulate matter loss during rinsing and on quantifying the particulate matter loss that occurs during incubation in the rumen itself. To quantify particulate matter loss during incubation, loss of small particles during the in situ incubation was studied using undegradable silica with different particle sizes. Particulate matter loss during incubation was limited to particles smaller than ~40 μm with a mean fractional particulate matter loss rate of 0.035 h-1 (first experiment) and 0.073 h-1 (second experiment) and an undegradable fraction of 0.001 and 0.050, respectively. In the second experiment, the fractional particulate matter loss rate after rinsing in a water bath at 50 strokes per minute (s.p.m.) (0.215 h-1) and the undegradable fraction at 20 s.p.m. (0.461) were significantly larger than that upon incubation in the rumen, whereas the fractional particulate matter loss rate (0.140 and 0.087 h-1, respectively) and the undegradable fraction (0.330 and 0.075, respectively) after rinsing at 30 and 40 s.p.m. did not differ with that upon rumen incubation. This new approach was applied to estimate the in situ fractional degradation rate of insoluble organic matter (OM) and insoluble nitrogen (N) in three different wheat yeast concentrates (WYC). These WYC were characterised by a high fraction of small particles and estimating their fractional degradation rate was not possible using the traditional washing machine rinsing method. The new rinsing method increased the mean non-washout fraction of OM and N in these products from 0.113 and 0.084 (washing machine method) to 0.670 and 0.782, respectively. The mean effective degradation (ED) without

  19. Optimal downlink rate allocation in multicell CDMA networks

    NARCIS (Netherlands)

    Endrayanto, A.I.; Gabor, A.F.; Boucherie, Richardus J.

    2007-01-01

    We study downlink rate allocation for a three cells CDMA system. Based on the discretized cell model, the rate optimization problem that maximizes the total downlink rate allocation is formulated. We propose an approximation procedure for obtaining a rate allocation in three cells case. Via

  20. Application of time-hopping UWB range-bit rate performance in the UWB sensor networks

    NARCIS (Netherlands)

    Nascimento, J.R.V. do; Nikookar, H.

    2008-01-01

    In this paper, the achievable range-bit rate performance is evaluated for Time-Hopping (TH) UWB networks complying with the FCC outdoor emission limits in the presence of Multiple Access Interference (MAI). Application of TH-UWB range-bit rate performance is presented for UWB sensor networks.

  1. Proteolytic degradation of the collagen network results in cartilage with inferior biomechanical properties

    NARCIS (Netherlands)

    Bank, R.A.; Koppele, J.M. te

    1999-01-01

    Swelling of cartilage, one of the early signs of osteoarthritis (OA), is considered to be the result of a collagen network that has lost its integrity. So far, no quantitative data directly support this assertion: combined measurements of the state of the collagen network per se and the degree of

  2. Evaluation of pesticide residue in grape juices and the effect of natural antioxidants on their degradation rate.

    Science.gov (United States)

    Picó, Yolanda; Kozmutza, Cornelia

    2007-11-01

    Various studies have been drawn toward the beneficial properties of fruit juices because they have several components, such as phenols, vitamins, and flavonoids, with antioxidant effects. However, fruit juices can also contain residues of pesticides used as standard pest control methods in crops. Many of these pesticides are degraded through oxidative mechanisms, and their persistence in juices can be enhanced by antioxidants. This study covers the degradation of four pesticides, aldicarb, demeton-S-methyl, fenamiphos, and methiocarb, to their respective sulfoxide and sulfone in grape juices, water (pH 3.5) and water (pH 3.5) with quercetin (one of the most important flavonoids of grape) added in an attempt to establish whether the presence of antioxidants can affect the degradation rate of pesticides. For this purpose, a multiresidue method based on solid-phase extraction (SPE) was developed for the simultaneous determination of these pesticides and their metabolites in commercial juices. The extraction procedure was carried out in C(18) columns. The subsequent elution of pesticides was performed with dichloromethane prior to the determination by liquid chromatography-tandem mass spectrometry (LC-MS/MS), using two precursor-product ion transitions. Average recoveries for all the pesticides studied were higher than 80%, with relative standard deviations lower than 15% in the concentration range 0.005-0.05 microg/mL, and the quantification limits achieved ranged from 0.1 to 4.6 microg/L. The results demonstrated that degradation was slower in fruit juices and aqueous solutions with quercetin than in water. Several commercial grape juices were also analyzed to establish the levels of these pesticides. Methiocarb, fenamiphos, and demeton-S-methyl were found at low levels in some samples.

  3. Assessment of the pectin degrading enzyme network of Aspergillus niger by functional genomics

    NARCIS (Netherlands)

    Martens-Uzunova, E.S.; Schaap, P.J.

    2009-01-01

    The saprobic fungus Aspergillus niger is an efficient producer of a suite of extracellular enzymes involved in carbohydrate modification and degradation. Genome mining has resulted in the prediction of at least 39 genes encoding enzymes involved in the depolymerisation of the backbone of pectin.

  4. Recovery Act: Energy Efficiency of Data Networks through Rate Adaptation (EEDNRA) - Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Matthew Andrews; Spyridon Antonakopoulos; Steve Fortune; Andrea Francini; Lisa Zhang

    2011-07-12

    This Concept Definition Study focused on developing a scientific understanding of methods to reduce energy consumption in data networks using rate adaptation. Rate adaptation is a collection of techniques that reduce energy consumption when traffic is light, and only require full energy when traffic is at full provisioned capacity. Rate adaptation is a very promising technique for saving energy: modern data networks are typically operated at average rates well below capacity, but network equipment has not yet been designed to incorporate rate adaptation. The Study concerns packet-switching equipment, routers and switches; such equipment forms the backbone of the modern Internet. The focus of the study is on algorithms and protocols that can be implemented in software or firmware to exploit hardware power-control mechanisms. Hardware power-control mechanisms are widely used in the computer industry, and are beginning to be available for networking equipment as well. Network equipment has different performance requirements than computer equipment because of the very fast rate of packet arrival; hence novel power-control algorithms are required for networking. This study resulted in five published papers, one internal report, and two patent applications, documented below. The specific technical accomplishments are the following: • A model for the power consumption of switching equipment used in service-provider telecommunication networks as a function of operating state, and measured power-consumption values for typical current equipment. • An algorithm for use in a router that adapts packet processing rate and hence power consumption to traffic load while maintaining performance guarantees on delay and throughput. • An algorithm that performs network-wide traffic routing with the objective of minimizing energy consumption, assuming that routers have less-than-ideal rate adaptivity. • An estimate of the potential energy savings in service-provider networks

  5. Transformation rules and degradation of CAHs by Fentonlike oxidation in growth ring of water distribution network-A review

    Science.gov (United States)

    Zhong, D.; Ma, W. C.; Jiang, X. Q.; Yuan, Y. X.; Yuan, Y.; Wang, Z. Q.; Fang, T. T.; Huang, W. Y.

    2017-08-01

    Chlorinated hydrocarbons are widely used as organic solvent and chemical raw materials. After treatment, water polluted with trichloroethylene (TCE)/tetrachloroethylene (PCE) can reach the water quality requirements, while water with trace amounts of TCE/PCE is still harmful to humans, which will cause cancers. Water distribution network is an extremely complicated system, in which adsorption, desorption, flocculation, movement, transformation and reduction will occur, leading to changes of TCE/PCE concentrations and products. Therefore, it is important to investigate the transformation rules of TCE/PCE in water distribution network. What’s more, growth-ring, including drinking water pipes deposits, can act as catalysts in Fenton-like reagent (H2O2). This review summarizes the status of transformation rules of CAHs in water distribution network. It also evaluates the effectiveness and fruit of CAHs degradation by Fenton-like reagent based on growth-ring. This review is important in solving the potential safety problems caused by TCE/PCE in water distribution network.

  6. Degradation rate of sludge/fly ash mixture used as landfill liner; Nedbrytningshastigheten foer taetskikt uppbyggda av slam och aska

    Energy Technology Data Exchange (ETDEWEB)

    Wikman, Karin; Berg, Magnus [AaF-Process AB, Stockholm (Sweden); Svensson, Malin; Ecke, Holger [Luleaa Univ. of Technology (Sweden)

    2005-10-01

    In order to be able to use mixtures of ash and sludge as landfill liner an important aspect is to demonstrate that the degradation of organic matter is slow enough. Therefore, the goal of this project has been to find out for how long a landfill liner material of sludge and ash will be stable and keep its function. The degradation of organic material in two different mixtures of sludge and ash has been studied in laboratory experiments. The rate of degradation was then estimated for barriers of sludge and ash, taking into account construction techniques (mixture, compaction, water content), climate conditions (freezing, drying) and biological processes (NaN{sub 3} additive). The effect of the degradation on the permeability has also been quantified. Organic material may disappear for the landfill liner material through 1) initial leaching of soluble organic material, 2) leaching of organic material after chemical reactions or 3) evaporation during biological degradation. Bacterial activity was not found in the sludge/ash mixtures during the experiments. Therefore, the organic material is probably reduced mainly though leaching according to 1) and 2). The leached amount of TOC (total organic carbon) was measured for all samples of sludge/ash in several experimental cycles. The leached amount of TOC was compared to the initial amount of TOC in the material. The results show a small initial reduction of organic material through leaching but the TOC content in the material is then stabilized. In relation to the total weight of the material the leaching of TOC was similar for the mixtures with 80 % ash and 20 % ash. However, this means that a larger amount of TOC was leached out from the mixtures with a high ash content since the initial amount of organic material was smaller. General conclusions about which ash-sludge ratio that is suitable for a landfill liner material could not be drawn from the experiments from a degradation point of view. If the initial

  7. Rate adaptation in ad hoc networks based on pricing

    CSIR Research Space (South Africa)

    Awuor, F

    2011-09-01

    Full Text Available that incorporates penalty (pricing) obtruded to users’ choices of transmission parameters to curb the self-interest behaviour. Therefore users determine their data rates and transmit power based on the perceived coupled interference at the intended receiver...

  8. Modelling pathways to Rubisco degradation: a structural equation network modelling approach.

    Directory of Open Access Journals (Sweden)

    Catherine Tétard-Jones

    Full Text Available 'Omics analysis (transcriptomics, proteomics quantifies changes in gene/protein expression, providing a snapshot of changes in biochemical pathways over time. Although tools such as modelling that are needed to investigate the relationships between genes/proteins already exist, they are rarely utilised. We consider the potential for using Structural Equation Modelling to investigate protein-protein interactions in a proposed Rubisco protein degradation pathway using previously published data from 2D electrophoresis and mass spectrometry proteome analysis. These informed the development of a prior model that hypothesised a pathway of Rubisco Large Subunit and Small Subunit degradation, producing both primary and secondary degradation products. While some of the putative pathways were confirmed by the modelling approach, the model also demonstrated features that had not been originally hypothesised. We used Bayesian analysis based on Markov Chain Monte Carlo simulation to generate output statistics suggesting that the model had replicated the variation in the observed data due to protein-protein interactions. This study represents an early step in the development of approaches that seek to enable the full utilisation of information regarding the dynamics of biochemical pathways contained within proteomics data. As these approaches gain attention, they will guide the design and conduct of experiments that enable 'Omics modelling to become a common place practice within molecular biology.

  9. The use of artificial neural network (ANN) for the prediction and simulation of oil degradation in wastewater by AOP.

    Science.gov (United States)

    Mustafa, Yasmen A; Jaid, Ghydaa M; Alwared, Abeer I; Ebrahim, Mothana

    2014-06-01

    The application of advanced oxidation process (AOP) in the treatment of wastewater contaminated with oil was investigated in this study. The AOP investigated is the homogeneous photo-Fenton (UV/H2O2/Fe(+2)) process. The reaction is influenced by the input concentration of hydrogen peroxide H2O2, amount of the iron catalyst Fe(+2), pH, temperature, irradiation time, and concentration of oil in the wastewater. The removal efficiency for the used system at the optimal operational parameters (H2O2 = 400 mg/L, Fe(+2) = 40 mg/L, pH = 3, irradiation time = 150 min, and temperature = 30 °C) for 1,000 mg/L oil load was found to be 72%. The study examined the implementation of artificial neural network (ANN) for the prediction and simulation of oil degradation in aqueous solution by photo-Fenton process. The multilayered feed-forward networks were trained by using a backpropagation algorithm; a three-layer network with 22 neurons in the hidden layer gave optimal results. The results show that the ANN model can predict the experimental results with high correlation coefficient (R (2) = 0.9949). The sensitivity analysis showed that all studied variables (H2O2, Fe(+2), pH, irradiation time, temperature, and oil concentration) have strong effect on the oil degradation. The pH was found to be the most influential parameter with relative importance of 20.6%.

  10. Topic-oriented community detection of rating-based social networks

    Directory of Open Access Journals (Sweden)

    Ali Reihanian

    2016-07-01

    Full Text Available Nowadays, real world social networks contain a vast range of information including shared objects, comments, following information, etc. Finding meaningful communities in this kind of networks is an interesting research area and has attracted the attention of many researchers. The community structure of complex networks reveals both their organization and hidden relations among their constituents. Most of the researches in the field of community detection mainly focus on the topological structure of the network without performing any content analysis. In recent years, a number of researches have proposed approaches which consider both the contents that are interchanged in networks, and the topological structures of the networks in order to find more meaningful communities. In this research, the effect of topic analysis in finding more meaningful communities in social networking sites in which the users express their feelings toward different objects (like movies by means of rating is demonstrated by performing extensive experiments.

  11. Natural Attenuation of Nonionic Surfactants Used in Hydraulic Fracturing Fluids: Degradation Rates, Pathways, and Mechanisms.

    Science.gov (United States)

    Heyob, Katie M; Blotevogel, Jens; Brooker, Michael; Evans, Morgan V; Lenhart, John J; Wright, Justin; Lamendella, Regina; Borch, Thomas; Mouser, Paula J

    2017-12-05

    Hydraulic fracturing fluids are injected into shales to extend fracture networks that enhance oil and natural gas production from unconventional reservoirs. Here we evaluated the biodegradability of three widely used nonionic polyglycol ether surfactants (alkyl ethoxylates (AEOs), nonylphenol ethoxylates (NPEOs), and polypropylene glycols (PPGs)) that function as weatherizers, emulsifiers, wetting agents, and corrosion inhibitors in injected fluids. Under anaerobic conditions, we observed complete removal of AEOs and NPEOs from solution within 3 weeks regardless of whether surfactants were part of a chemical mixture or amended as individual additives. Microbial enzymatic chain shortening was responsible for a shift in ethoxymer molecular weight distributions and the accumulation of the metabolite acetate. PPGs bioattenuated the slowest, producing sizable concentrations of acetone, an isomer of propionaldehyde. Surfactant chain shortening was coupled to an increased abundance of the diol dehydratase gene cluster (pduCDE) in Firmicutes metagenomes predicted from the 16S rRNA gene. The pduCDE enzymes are responsible for cleaving ethoxylate chain units into aldehydes before their fermentation into alcohols and carboxylic acids. These data provide new mechanistic insight into the environmental fate of hydraulic fracturing surfactants after accidental release through chain shortening and biotransformation, emphasizing the importance of compound structure disclosure for predicting biodegradation products.

  12. Evaluating portland cement concrete degradation by sulphate exposure through artificial neural networks modeling

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Douglas Nunes de; Bourguignon, Lucas Gabriel Garcia; Tolentino, Evandro, E-mail: tolentino@timoteo.cefetmg.br [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET-MG), Timoteo, MG (Brazil); Costa, Rodrigo Moyses, E-mail: rodrigo@moyses.com.br [Universidade de Itauna, Itauna, MG (Brazil); Tello, Cledola Cassia Oliveira de, E-mail: tellocc@cdtn.br [Centro de Desenvolvimento da Tecnologia Nucelar (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    A concrete is durable if it has accomplished the desired service life in the environment in which it is exposed. The durability of concrete materials can be limited as a result of adverse performance of its cement-paste matrix or aggregate constituents under either chemical or physical attack. Among other aggressive chemical exposures, the sulphate attack is an important concern. Water, soils and gases, which contain sulphate, represent a potential threat to the durability of concrete structures. Sulphate attack in concrete leads to the conversion of the hydration products of cement to ettringite, gypsum, and other phases, and also it leads to the destabilization of the primary strength generating calcium silicate hydrate (C-S-H) gel. The formation of ettringite and gypsum is common in cementitious systems exposed to most types of sulphate solutions. The present work presents the application of the neural networks for estimating deterioration of various concrete mixtures due to exposure to sulphate solutions. A neural networks model was constructed, trained and tested using the available database. In general, artificial neural networks could be successfully used in function approximation problems in order to approach the data generation function. Once data generation function is known, artificial neural network structure is tested using data not presented to the network during training. This paper is intent to provide the technical requirements related to the production of a durable concrete to be used in the structures of the Brazilian near-surface repository of radioactive wastes. (author)

  13. Network Events on Multiple Space and Time Scales in Cultured Neural Networks and in a Stochastic Rate Model.

    Directory of Open Access Journals (Sweden)

    Guido Gigante

    2015-11-01

    Full Text Available Cortical networks, in-vitro as well as in-vivo, can spontaneously generate a variety of collective dynamical events such as network spikes, UP and DOWN states, global oscillations, and avalanches. Though each of them has been variously recognized in previous works as expression of the excitability of the cortical tissue and the associated nonlinear dynamics, a unified picture of the determinant factors (dynamical and architectural is desirable and not yet available. Progress has also been partially hindered by the use of a variety of statistical measures to define the network events of interest. We propose here a common probabilistic definition of network events that, applied to the firing activity of cultured neural networks, highlights the co-occurrence of network spikes, power-law distributed avalanches, and exponentially distributed 'quasi-orbits', which offer a third type of collective behavior. A rate model, including synaptic excitation and inhibition with no imposed topology, synaptic short-term depression, and finite-size noise, accounts for all these different, coexisting phenomena. We find that their emergence is largely regulated by the proximity to an oscillatory instability of the dynamics, where the non-linear excitable behavior leads to a self-amplification of activity fluctuations over a wide range of scales in space and time. In this sense, the cultured network dynamics is compatible with an excitation-inhibition balance corresponding to a slightly sub-critical regime. Finally, we propose and test a method to infer the characteristic time of the fatigue process, from the observed time course of the network's firing rate. Unlike the model, possessing a single fatigue mechanism, the cultured network appears to show multiple time scales, signalling the possible coexistence of different fatigue mechanisms.

  14. Near cost-optimal inventory control policies for divergent networks under fill rate constraints

    NARCIS (Netherlands)

    van der Heijden, Matthijs C.

    2000-01-01

    We deal with the optimisation of stock levels in general divergent networks under a periodic review, order-up-to (R, S) policy. The goal is to attain target fill rates, while the total holding costs in the entire network are minimised. To this end, we first present a method for the fast calculation

  15. The association between social networks and self-rated risk of HIV ...

    African Journals Online (AJOL)

    Elizabeth J. Lyimo

    2014-03-18

    Mar 18, 2014 ... Participation in bridging networks was greater among females (25%) than males (12%, p , .005). Of ... association between bonding and bridging social networks on self-rated risk of HIV among study participants. However, sexually .... the social ecological model (SEM) described by Bronfenbrenner (1994).

  16. A random walk solution for modeling solute transport with network reactions and multi-rate mass transfer in heterogeneous systems: Impact of biofilms

    Science.gov (United States)

    Henri, Christopher V.; Fernàndez-Garcia, Daniel

    2015-12-01

    The interplay between the spatial variability of the aquifer hydraulic properties, mass transfer due to sub-grid heterogeneity and chemical reactions often complicates reactive transport simulations. It is well documented that hydro-biochemical properties are ubiquitously heterogeneous and that diffusion and slow advection at the sub-grid scale typically leads to the conceptualization of an aquifer as a multi-porosity system. Within this context, chemical reactions taking place in mobile/immobile water regions can be substantially different between each other. This paper presents a particle-based method that can efficiently simulate heterogeneity, network reactions and multi-rate mass transfer. The approach is based on the development of transition probabilities that describe the likelihood that particles belonging to a given species and mobile/immobile domain at a given time will be transformed into another species and mobile/immobile domain afterwards. The joint effect of mass transfer and sequential degradation is shown to be non-trivial. A characteristic rebound of degradation products can be observed. This late rebound of concentrations is not driven by any change in the flow regime (e.g., pumping ceases in the pump-and-treat remediation strategy) but due to the natural interplay between mass transfer and chemical reactions. To illustrate that the method can simultaneously represent mass transfer, spatially varying properties and network reactions without numerical problems, we have simulated the degradation of tetrachloroethylene (PCE) in a three-dimensional fully heterogeneous aquifer subjected to rate-limited mass transfer. Two types of degradation modes were considered to compare the effect of an active biofilm with that of clay pods present in the aquifer. Results of the two scenarios display significantly differences. Biofilms that promote the degradation of compounds in an immobile region are shown to significantly enhance degradation, rapidly producing

  17. Designing Predictive Diagnose Method for Insulation Resistance Degradation of the Electrical Power Cables from Neutral Insulated Power Networks

    Science.gov (United States)

    Dobra, R.; Pasculescu, D.; Risteiu, M.; Buica, G.; Jevremović, V.

    2017-06-01

    This paper describe some possibilities to minimize voltages switching-off risks from the mining power networks, in case of insulated resistance faults by using a predictive diagnose method. The cables from the neutral insulated power networks (underground mining) are designed to provide a flexible electrical connection between portable or mobile equipment and a point of supply, including main feeder cable for continuous miners, pump cable, and power supply cable. An electronic protection for insulated resistance of mining power cables can be made using this predictive strategy. The main role of electronic relays for insulation resistance degradation of the electrical power cables, from neutral insulated power networks, is to provide a permanent measurement of the insulated resistance between phases and ground, in order to switch-off voltage when the resistance value is below a standard value. The automat system of protection is able to signalize the failure and the human operator will be early informed about the switch-off power and will have time to take proper measures to fix the failure. This logic for fast and automat switch-off voltage without aprioristic announcement is suitable for the electrical installations, realizing so a protection against fires and explosion. It is presented an algorithm and an anticipative relay for insulated resistance control from three-phase low voltage installations with insulated neutral connection.

  18. Degraded Operational Environment: Integration of Social Network Infrastructure Concept in a Traditional Military C2 System

    Science.gov (United States)

    2013-06-01

    Communication Applet) UNIGE – D.I.M.E. Using a free application as “MIT APP Inventor ” Android Software Development Kit DEGRADED C2 ICCRTS 2013...June 19 - 21, 2013 - Alexandria, VIRGINIA (US) 18/26 Development of C24U applet (Command & Control For You) UNIGE – D.I.M.E. MIT App Inventor s B...appinventor.mit.edu/ releaseupdate My Projects Viewer Welcome to the App Inventor beta release_ Be sure to check the list of Design Learn (Debugging) known issues

  19. Fiber Segment-Based Degradation Methods for a Finite Element-Informed Structural Brain Network

    Science.gov (United States)

    2013-11-01

    structural injury translates to functional network changes. 20 5. References 1. Pascrell House Home Page. Congressional Brain Injury Task Force... Audiovisual Stimulation by Partial Directed Coherence Analysis. IEEE Transactions on Biomedical Engineering 2009, 56 (11), 2721–2724. 21. Horgan, T. J

  20. Time-delay polynomial networks and rates of approximation

    Directory of Open Access Journals (Sweden)

    Irwin W. Sandberg

    1998-01-01

    Full Text Available We consider a large family of finite memory causal time-invariant maps G from an input set S to a set of ℝ-valued functions, with the members of both sets of functions defined on the nonnegative integers, and we give an upper bound on the error in approximating a G using a two-stage structure consisting of a tapped delay line and a static polynomial network N . This upper bound depends on the degree of the multivariable polynomial that characterizes N. Also given is a lower bound on the worst-case error in approximating a G using polynomials of a fixed maximum degree. These upper and lower bounds differ only by a multiplicative constant. We also give a corresponding result for the approximation of not-necessarily-causal input–output maps with inputs and outputs that may depend on more than one variable. This result is of interest, for example, in connection with image processing.

  1. Active random noise control using adaptive learning rate neural networks with an immune feedback law

    Science.gov (United States)

    Sasaki, Minoru; Kuribayashi, Takumi; Ito, Satoshi

    2005-12-01

    In this paper an active random noise control using adaptive learning rate neural networks with an immune feedback law is presented. The adaptive learning rate strategy increases the learning rate by a small constant if the current partial derivative of the objective function with respect to the weight and the exponential average of the previous derivatives have the same sign, otherwise the learning rate is decreased by a proportion of its value. The use of an adaptive learning rate attempts to keep the learning step size as large as possible without leading to oscillation. In the proposed method, because of the immune feedback law change a learning rate of the neural networks individually and adaptively, it is expected that a cost function minimize rapidly and training time is decreased. Numerical simulations and experiments of active random noise control with the transfer function of the error path will be performed, to validate the convergence properties of the adaptive learning rate Neural Networks with the immune feedback law. Control results show that adaptive learning rate Neural Networks control structure can outperform linear controllers and conventional neural network controller for the active random noise control.

  2. A Unified Approach for Calculating Error Rates of 10 Gbps WDM Network in Presence of Higher Order Dispersion

    Science.gov (United States)

    Kaur, Karamjit; Singh, Hardeep

    2017-12-01

    The lack of regeneration in all optical networks makes the data susceptible to network malfunctions, misconfigurations and signal impairments. As most of the effects are additive in nature, the signal quality is degraded by the time it reaches at the destination end making optical monitors installation a need of the day to maintain the service-level agreements for the end users. The physical layer impairments that need to be monitored are broadly classified as linear and nonlinear impairments. As the nonlinear impairments depends on the network state, it is difficult to preestimate them, while linear impairments can be easily determined from the type of fiber, wavelength/waveband, amplifier and environmental conditions. Among the linear impairments, dispersion, amplified spontaneous emission noise and attenuation are more dominating. In the present work, an effort is given to study the impact of dispersion on system quality, quantified through bit error rate (BER) and Q-value. Eye diagrams obtained at the receiver end are used for calculating system response. The curves obtained for BER and Q-value are further processed for curve fitting and suitable fifth-order polynomial equation is calculated representing the system response. Implementation of this equation in routing applications is discussed.

  3. Analysis of Blocking Rate and Bandwidth Usage of Mobile IPTV Services in Wireless Cellular Networks

    Directory of Open Access Journals (Sweden)

    Mingfu Li

    2014-01-01

    Full Text Available Mobile IPTV services over wireless cellular networks become more and more popular, owing to the significant growth in access bandwidth of wireless cellular networks such as 3G/4G and WiMAX. However, the spectrum resources of wireless cellular networks is rare. How to enhance the spectral efficiency of mobile networks becomes an important issue. Unicast, broadcast, and multicast are the most important transport schemes for offering mobile IPTV services over wireless cellular networks. Therefore, bandwidth usages and blocking rates of unicast, broadcast, and multicast IPTV services were analyzed and compared in this paper. Simulations were also conducted to validate the analytical results. Numerical results demonstrate that the presented analysis is correct, and multicast scheme achieves the best bandwidth usage and blocking rate performance, relative to the other two schemes.

  4. Analysis of blocking rate and bandwidth usage of mobile IPTV services in wireless cellular networks.

    Science.gov (United States)

    Li, Mingfu

    2014-01-01

    Mobile IPTV services over wireless cellular networks become more and more popular, owing to the significant growth in access bandwidth of wireless cellular networks such as 3G/4G and WiMAX. However, the spectrum resources of wireless cellular networks is rare. How to enhance the spectral efficiency of mobile networks becomes an important issue. Unicast, broadcast, and multicast are the most important transport schemes for offering mobile IPTV services over wireless cellular networks. Therefore, bandwidth usages and blocking rates of unicast, broadcast, and multicast IPTV services were analyzed and compared in this paper. Simulations were also conducted to validate the analytical results. Numerical results demonstrate that the presented analysis is correct, and multicast scheme achieves the best bandwidth usage and blocking rate performance, relative to the other two schemes.

  5. Modeling multiple time scale firing rate adaptation in a neural network of local field potentials.

    Science.gov (United States)

    Lundstrom, Brian Nils

    2015-02-01

    In response to stimulus changes, the firing rates of many neurons adapt, such that stimulus change is emphasized. Previous work has emphasized that rate adaptation can span a wide range of time scales and produce time scale invariant power law adaptation. However, neuronal rate adaptation is typically modeled using single time scale dynamics, and constructing a conductance-based model with arbitrary adaptation dynamics is nontrivial. Here, a modeling approach is developed in which firing rate adaptation, or spike frequency adaptation, can be understood as a filtering of slow stimulus statistics. Adaptation dynamics are modeled by a stimulus filter, and quantified by measuring the phase leads of the firing rate in response to varying input frequencies. Arbitrary adaptation dynamics are approximated by a set of weighted exponentials with parameters obtained by fitting to a desired filter. With this approach it is straightforward to assess the effect of multiple time scale adaptation dynamics on neural networks. To demonstrate this, single time scale and power law adaptation were added to a network model of local field potentials. Rate adaptation enhanced the slow oscillations of the network and flattened the output power spectrum, dampening intrinsic network frequencies. Thus, rate adaptation may play an important role in network dynamics.

  6. Decentralized control of transmission rates in energy-critical wireless networks

    KAUST Repository

    Xia, Li

    2013-06-01

    In this paper, we discuss the decentralized optimization of delay and energy consumption in a multi-hop wireless network. The goal is to minimize the energy consumption of energy-critical nodes and the overall packet transmission delay of the network. The transmission rates of energy-critical nodes are adjustable according to the local information of nodes, i.e., the length of packets queued. The multi-hop network is modeled as a queueing network.We prove that the system performance is monotone w.r.t. (with respect to) the transmission rate, thus the “bang-bang” control is an optimal control. We also prove that there exists a threshold type control policy which is optimal. We propose a decentralized algorithm to control transmission rates of these energy-critical nodes. Some simulation experiments are conducted to demonstrate the effectiveness of our approach.

  7. Simulation of Missile Autopilot with Two-Rate Hybrid Neural Network System

    Directory of Open Access Journals (Sweden)

    ASTROV, I.

    2007-04-01

    Full Text Available This paper proposes a two-rate hybrid neural network system, which consists of two artificial neural network subsystems. These neural network subsystems are used as the dynamic subsystems controllers.1 This is because such neuromorphic controllers are especially suitable to control complex systems. An illustrative example - two-rate neural network hybrid control of decomposed stochastic model of a rigid guided missile over different operating conditions - was carried out using the proposed two-rate state-space decomposition technique. This example demonstrates that this research technique results in simplified low-order autonomous control subsystems with various speeds of actuation, and shows the quality of the proposed technique. The obtained results show that the control tasks for the autonomous subsystems can be solved more qualitatively than for the original system. The simulation and animation results with use of software package Simulink demonstrate that this research technique would work for real-time stochastic systems.

  8. Effect of physician collaboration network on hospitalization cost and readmission rate.

    Science.gov (United States)

    Uddin, Shahadat; Hossain, Liaquat; Kelaher, Margaret

    2012-10-01

    Previous studies have documented the effect of collaboration among physicians on the effectiveness in delivering health services and in producing better patient outcomes. However, there is no systematic empirical study suggesting the underlying relationship between the collaboration network of physicians and its effect on hospitalization cost and readmission rate. In this study, we explore the effect of different attributes (i.e. degree centrality, betweenness centrality, network density and network distance) of physician collaboration network (PCN) on hospitalization cost and readmission rate. We analyse health insurance claim data set of total hip replacement (THR) patients to construct PCN and to test the effect of its network attributes on hospitalization cost and readmission rate. We consider patient age as moderating factor, which could affect the relation of the PCN attributes with hospitalization cost and readmission rate. We find that degree centrality (i.e. level of involvement) and network density (i.e. level of connectedness) of PCN are negatively correlated with hospitalization cost and readmission rate. In contrast, betweenness centrality (i.e. capacity to control the flow of information) is found positively correlated with hospitalization cost and readmission rate. Distance (i.e. embeddedness of actors in a network) is found positively correlated with hospitalization cost but negatively correlated with readmission rate. We do not notice any significant impact of patient age on the relation of PCN attributes with hospitalization cost and readmission rate. The results show that the structure of PCNs is related to indicators of hospital costs and quality (readmission). In their respective hospitals, health-care managers or administrators may follow our research findings to reduce cost and improve quality.

  9. Maximum Data Collection Rate Routing Protocol Based on Topology Control for Rechargeable Wireless Sensor Networks.

    Science.gov (United States)

    Lin, Haifeng; Bai, Di; Gao, Demin; Liu, Yunfei

    2016-07-30

    In Rechargeable Wireless Sensor Networks (R-WSNs), in order to achieve the maximum data collection rate it is critical that sensors operate in very low duty cycles because of the sporadic availability of energy. A sensor has to stay in a dormant state in most of the time in order to recharge the battery and use the energy prudently. In addition, a sensor cannot always conserve energy if a network is able to harvest excessive energy from the environment due to its limited storage capacity. Therefore, energy exploitation and energy saving have to be traded off depending on distinct application scenarios. Since higher data collection rate or maximum data collection rate is the ultimate objective for sensor deployment, surplus energy of a node can be utilized for strengthening packet delivery efficiency and improving the data generating rate in R-WSNs. In this work, we propose an algorithm based on data aggregation to compute an upper data generation rate by maximizing it as an optimization problem for a network, which is formulated as a linear programming problem. Subsequently, a dual problem by introducing Lagrange multipliers is constructed, and subgradient algorithms are used to solve it in a distributed manner. At the same time, a topology controlling scheme is adopted for improving the network's performance. Through extensive simulation and experiments, we demonstrate that our algorithm is efficient at maximizing the data collection rate in rechargeable wireless sensor networks.

  10. Selection on Network Dynamics Drives Differential Rates of Protein Domain Evolution.

    Directory of Open Access Journals (Sweden)

    Brian K Mannakee

    2016-07-01

    Full Text Available The long-held principle that functionally important proteins evolve slowly has recently been challenged by studies in mice and yeast showing that the severity of a protein knockout only weakly predicts that protein's rate of evolution. However, the relevance of these studies to evolutionary changes within proteins is unknown, because amino acid substitutions, unlike knockouts, often only slightly perturb protein activity. To quantify the phenotypic effect of small biochemical perturbations, we developed an approach to use computational systems biology models to measure the influence of individual reaction rate constants on network dynamics. We show that this dynamical influence is predictive of protein domain evolutionary rate within networks in vertebrates and yeast, even after controlling for expression level and breadth, network topology, and knockout effect. Thus, our results not only demonstrate the importance of protein domain function in determining evolutionary rate, but also the power of systems biology modeling to uncover unanticipated evolutionary forces.

  11. Status Report - Cane Fiberboard Properties and Degradation Rates for Storage of the 9975 Shipping Package in KAMS

    Energy Technology Data Exchange (ETDEWEB)

    Daugherty, W. L.

    2013-01-31

    Thermal, mechanical and physical properties have been measured on cane fiberboard samples following accelerated aging for up to approximately 7 years. The aging environments have included elevated temperature < 250 ?F (the maximum allowed service temperature for fiberboard in 9975 packages) and elevated humidity. The results from this testing have been analyzed, and aging models fit to the data. Correlations relating several properties (thermal conductivity, energy absorption, weight loss and height decrease) to their rate of change in potential storage environments have been developed. Combined with an estimate of the actual conditions the fiberboard experiences in KAMS, these models allow development of service life predictions. Some of the predicted degradation rates presented in this report are relatively extreme. However, these relate to environments that do not exist within KAMS, or would be postulated only as upset conditions that would not likely persist for an extended period. For a typical package with ~10 watts internal heat load or less, and ambient temperatures below 90 ?F, the fiberboard experiences storage conditions less severe than any of the aging environments. Little or no degradation of the fiberboard is expected for typical storage conditions. It should be noted that the ultimate service life will be determined by the cumulative effect of degradation from all the conditions these packages might encounter. The assumptions and inputs behind the models in this report should be well understood before attempting to identify an actual service life in KAMS. Additional data continue to be collected to permit future refinements to the models and assumptions. For developing service life predictions, the ambient conditions within KAMS can be reasonably identified, and the temperature profiles within the various packages (with a range of heat loads and at varying locations within an array of packages) can be calculated. However, the humidity within the

  12. Determination of rate constants and branching ratios for TCE degradation by zero-valent iron using a chain decay multispecies model.

    Science.gov (United States)

    Hwang, Hyoun-Tae; Jeen, Sung-Wook; Sudicky, Edward A; Illman, Walter A

    2015-01-01

    The applicability of a newly-developed chain-decay multispecies model (CMM) was validated by obtaining kinetic rate constants and branching ratios along the reaction pathways of trichloroethene (TCE) reduction by zero-valent iron (ZVI) from column experiments. Changes in rate constants and branching ratios for individual reactions for degradation products over time for two columns under different geochemical conditions were examined to provide ranges of those parameters expected over the long-term. As compared to the column receiving deionized water, the column receiving dissolved CaCO3 showed higher mean degradation rates for TCE and all of its degradation products. However, the column experienced faster reactivity loss toward TCE degradation due to precipitation of secondary carbonate minerals, as indicated by a higher value for the ratio of maximum to minimum TCE degradation rate observed over time. From the calculated branching ratios, it was found that TCE and cis-dichloroethene (cis-DCE) were dominantly dechlorinated to chloroacetylene and acetylene, respectively, through reductive elimination for both columns. The CMM model, validated by the column test data in this study, provides a convenient tool to determine simultaneously the critical design parameters for permeable reactive barriers and natural attenuation such as rate constants and branching ratios. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Determination of rate constants and branching ratios for TCE degradation by zero-valent iron using a chain decay multispecies model

    Science.gov (United States)

    Hwang, Hyoun-Tae; Jeen, Sung-Wook; Sudicky, Edward A.; Illman, Walter A.

    2015-06-01

    The applicability of a newly-developed chain-decay multispecies model (CMM) was validated by obtaining kinetic rate constants and branching ratios along the reaction pathways of trichloroethene (TCE) reduction by zero-valent iron (ZVI) from column experiments. Changes in rate constants and branching ratios for individual reactions for degradation products over time for two columns under different geochemical conditions were examined to provide ranges of those parameters expected over the long-term. As compared to the column receiving deionized water, the column receiving dissolved CaCO3 showed higher mean degradation rates for TCE and all of its degradation products. However, the column experienced faster reactivity loss toward TCE degradation due to precipitation of secondary carbonate minerals, as indicated by a higher value for the ratio of maximum to minimum TCE degradation rate observed over time. From the calculated branching ratios, it was found that TCE and cis-dichloroethene (cis-DCE) were dominantly dechlorinated to chloroacetylene and acetylene, respectively, through reductive elimination for both columns. The CMM model, validated by the column test data in this study, provides a convenient tool to determine simultaneously the critical design parameters for permeable reactive barriers and natural attenuation such as rate constants and branching ratios.

  14. Visibility Enhancement of Scene Images Degraded by Foggy Weather Conditions with Deep Neural Networks

    Directory of Open Access Journals (Sweden)

    Farhan Hussain

    2016-01-01

    Full Text Available Nowadays many camera-based advanced driver assistance systems (ADAS have been introduced to assist the drivers and ensure their safety under various driving conditions. One of the problems faced by drivers is the faded scene visibility and lower contrast while driving in foggy conditions. In this paper, we present a novel approach to provide a solution to this problem by employing deep neural networks. We assume that the fog in an image can be mathematically modeled by an unknown complex function and we utilize the deep neural network to approximate the corresponding mathematical model for the fog. The advantages of our technique are as follows: (i its real-time operation and (ii being based on minimal input, that is, a single image, and exhibiting robustness/generalization for various unseen image data. Experiments carried out on various synthetic images indicate that our proposed technique has the abilities to approximate the corresponding fog function reasonably and remove it for better visibility and safety.

  15. Resource management for multimedia services in high data rate wireless networks

    CERN Document Server

    Zhang, Ruonan; Pan, Jianping

    2017-01-01

    This brief offers a valuable resource on principles of quality-of-service (QoS) provisioning and the related link-layer resource management techniques for high data-rate wireless networks. The primary emphasis is on protocol modeling and analysis. It introduces media access control (MAC) protocols, standards of wireless local area networks (WLANs), wireless personal area networks (WPANs), and wireless body area networks (WBANs), discussing their key technologies, applications, and deployment scenarios. The main analytical approaches and models for performance analysis of the fundamental resource scheduling mechanisms, including the contention-based, reservation-based, and hybrid MAC, are presented. To help readers understand and evaluate system performance, the brief contains a range of simulation results. In addition, a thorough bibliography provides an additional tool. This brief is an essential resource for engineers, researchers, students, and users of wireless networks.

  16. Inferring Transition Rates of Networks from Populations in Continuous-Time Markov Processes.

    Science.gov (United States)

    Dixit, Purushottam D; Jain, Abhinav; Stock, Gerhard; Dill, Ken A

    2015-11-10

    We are interested inferring rate processes on networks. In particular, given a network's topology, the stationary populations on its nodes, and a few global dynamical observables, can we infer all the transition rates between nodes? We draw inferences using the principle of maximum caliber (maximum path entropy). We have previously derived results for discrete-time Markov processes. Here, we treat continuous-time processes, such as dynamics among metastable states of proteins. The present work leads to a particularly important analytical result: namely, that when the network is constrained only by a mean jump rate, the rate matrix is given by a square-root dependence of the rate, kab ∝ (πb/πa)(1/2), on πa and πb, the stationary-state populations at nodes a and b. This leads to a fast way to estimate all of the microscopic rates in the system. As an illustration, we show that the method accurately predicts the nonequilibrium transition rates in an in silico gene expression network and transition probabilities among the metastable states of a small peptide at equilibrium. We note also that the method makes sensible predictions for so-called extra-thermodynamic relationships, such as those of Bronsted, Hammond, and others.

  17. Exchange rate prediction with multilayer perceptron neural network using gold price as external factor

    Directory of Open Access Journals (Sweden)

    Mohammad Fathian

    2012-04-01

    Full Text Available In this paper, the problem of predicting the exchange rate time series in the foreign exchange rate market is going to be solved using a time-delayed multilayer perceptron neural network with gold price as external factor. The input for the learning phase of the artificial neural network are the exchange rate data of the last five days plus the gold price in two different currencies of the exchange rate as the external factor for helping the artificial neural network improving its forecast accuracy. The five-day delay has been chosen because of the weekly cyclic behavior of the exchange rate time series with the consideration of two holidays in a week. The result of forecasts are then compared with using the multilayer peceptron neural network without gold price external factor by two most important evaluation techniques in the literature of exchange rate prediction. For the experimental analysis phase, the data of three important exchange rates of EUR/USD, GBP/USD, and USD/JPY are used.

  18. Influence of the formation- and passivation rate of boron-oxygen defects for mitigating carrier-induced degradation in silicon within a hydrogen-based model

    Energy Technology Data Exchange (ETDEWEB)

    Hallam, Brett, E-mail: brett.hallam@unsw.edu.au; Abbott, Malcolm; Nampalli, Nitin; Hamer, Phill; Wenham, Stuart [School of Photovoltaics and Renewable Energy Engineering, Level 1 Tyree Energy Technologies Building, University of New South Wales, Kensington, NSW 2052 (Australia)

    2016-02-14

    A three-state model is used to explore the influence of defect formation- and passivation rates of carrier-induced degradation related to boron-oxygen complexes in boron-doped p-type silicon solar cells within a hydrogen-based model. The model highlights that the inability to effectively mitigate carrier-induced degradation at elevated temperatures in previous studies is due to the limited availability of defects for hydrogen passivation, rather than being limited by the defect passivation rate. An acceleration of the defect formation rate is also observed to increase both the effectiveness and speed of carrier-induced degradation mitigation, whereas increases in the passivation rate do not lead to a substantial acceleration of the hydrogen passivation process. For high-throughput mitigation of such carrier-induced degradation on finished solar cell devices, two key factors were found to be required, high-injection conditions (such as by using high intensity illumination) to enable an acceleration of defect formation whilst simultaneously enabling a rapid passivation of the formed defects, and a high temperature to accelerate both defect formation and defect passivation whilst still ensuring an effective mitigation of carrier-induced degradation.

  19. Deriving fractional rate of degradation of logistic-exponential (LE) model to evaluate early in vitro fermentation.

    Science.gov (United States)

    Wang, M; Sun, X Z; Tang, S X; Tan, Z L; Pacheco, D

    2013-06-01

    Water-soluble components of feedstuffs are mainly utilized during the early phase of microbial fermentation, which could be deemed an important determinant of gas production behavior in vitro. Many studies proposed that the fractional rate of degradation (FRD) estimated by fitting gas production curves to mathematical models might be used to characterize the early incubation for in vitro systems. In this study, the mathematical concept of FRD was developed on the basis of the Logistic-Exponential (LE) model, with initial gas volume being zero (LE0). The FRD of the LE0 model exhibits a continuous increase from initial (FRD 0) toward final asymptotic value (FRD F) with longer incubation time. The relationships between the FRD and gas production at incubation times 2, 4, 6, 8, 12 and 24 h were compared for four models, in addition to LE0, Generalization of the Mitscherlich (GM), c th order Michaelis-Menten (MM) and Exponential with a discrete LAG (EXPLAG). A total of 94 in vitro gas curves from four subsets with a wide range of feedstuffs from different laboratories and incubation periods were used for model testing. Results indicated that compared with the GM, MM and EXPLAG models, the FRD of LE0 model consistently had stronger correlations with gas production across the four subsets, especially at incubation times 2, 4, 6, 8 and 12 h. Thus, the LE0 model was deemed to provide a better representation of the early fermentation rates. Furthermore, the FRD 0 also exhibited strong correlations (P parameter of rate.

  20. Impact of window decrement rate on TCP performance in an adhoc network

    Science.gov (United States)

    Suherman; Hutasuhut, Arief T. W.; Badra, Khaldun; Al-Akaidi, Marwan

    2017-09-01

    Transmission control protocol (TCP) is a reliable transport protocol handling end to end connection in TCP/IP stack. It works well in copper or optical fibre link, but experiences increasing delay in wireless network. Further, TCP experiences multiple retransmissions due to higher collision probability within wireless network. The situation may get worsen in an ad hoc network. This paper examines the impact half window or window reduction rate to the overall TCP performances. The evaluation using NS-2 simulator shows that the smaller the window decrement rate results the smaller end to end delay. Delay is reduced to 17.05% in average when window decrement rate decreases. Average jitter also decreases 4.15%, while packet loss is not affected.

  1. The efficacy of centralized flow rate control in 802.11-based wireless mesh networks

    KAUST Repository

    Jamshaid, K.

    2013-06-13

    Commodity WiFi-based wireless mesh networks (WMNs) can be used to provide last mile Internet access. These networks exhibit extreme unfairness with backlogged traffic sources. Current solutions propose distributed source-rate control algorithms requiring link-layer or transport-layer changes on all mesh nodes. This is often infeasible in large practical deployments. In wireline networks, router-assisted rate control techniques have been proposed for use alongside end-to-end mechanisms. We wish to evaluate the feasibility of establishing similar centralized control via gateways in WMNs. In this paper, we focus on the efficacy of this control rather than the specifics of the controller design mechanism. We answer the question: Given sources that react predictably to congestion notification, can we enforce a desired rate allocation through a single centralized controller? The answer is not obvious because flows experience varying contention levels, and transmissions are scheduled by a node using imperfect local knowledge. We find that common router-assisted flow control schemes used in wired networks fail in WMNs because they assume that (1) links are independent, and (2) router queue buildups are sufficient for detecting congestion. We show that non-work-conserving, rate-based centralized scheduling can effectively enforce rate allocation. It can achieve results comparable to source rate limiting, without requiring any modifications to mesh routers or client devices. 2013 Jamshaid et al.; licensee Springer.

  2. A prediction method for the wax deposition rate based on a radial basis function neural network

    Directory of Open Access Journals (Sweden)

    Ying Xie

    2017-06-01

    Full Text Available The radial basis function neural network is a popular supervised learning tool based on machinery learning technology. Its high precision having been proven, the radial basis function neural network has been applied in many areas. The accumulation of deposited materials in the pipeline may lead to the need for increased pumping power, a decreased flow rate or even to the total blockage of the line, with losses of production and capital investment, so research on predicting the wax deposition rate is significant for the safe and economical operation of an oil pipeline. This paper adopts the radial basis function neural network to predict the wax deposition rate by considering four main influencing factors, the pipe wall temperature gradient, pipe wall wax crystal solubility coefficient, pipe wall shear stress and crude oil viscosity, by the gray correlational analysis method. MATLAB software is employed to establish the RBF neural network. Compared with the previous literature, favorable consistency exists between the predicted outcomes and the experimental results, with a relative error of 1.5%. It can be concluded that the prediction method of wax deposition rate based on the RBF neural network is feasible.

  3. Clusters of reaction rates and concentrations in protein networks such as the phosphotransferase system.

    Science.gov (United States)

    Härdin, Hanna M; Zagaris, Antonios; Willms, Allan R; Westerhoff, Hans V

    2014-01-01

    To understand the functioning of living cells, it is often helpful or even necessary to exploit inherent timescale disparities and focus on long-term dynamic behaviour. In the present study, we explore this type of behaviour for the biochemical network of the phosphotransferase system. We show that, during the slow phase that follows a fast initial transient, the network reaction rates are partitioned into clusters corresponding to connected parts of the reaction network. Rates within any of these clusters assume essentially the same value: differences within each cluster are vastly smaller than that from one cluster to another. This rate clustering induces an analogous clustering of the reactive compounds: only the molecular concentrations on the interface between these clusters are produced and consumed at substantially different rates and hence change considerably during the slow phase. The remaining concentrations essentially assume their steady-state values already by the end of the transient phase. Further, we find that this clustering phenomenon occurs for a large number of parameter values and also for models with different topologies; to each of these models, there corresponds a particular network partitioning. Our results show that, in spite of its complexity, the phosphotransferase system tends to behave in a rather simple (yet versatile) way. The persistence of clustering for the perturbed models we examined suggests that it is likely to be encountered in various environmental conditions, as well as in other signal transduction pathways with network structures similar to that of the phosphotransferase system. © 2013 FEBS.

  4. Explicit Rate Adjustment (ERA: Responsiveness, Network Utilization Efficiency and Fairness for Layered Multicast

    Directory of Open Access Journals (Sweden)

    Somnuk PUANGPRONPITAG

    2005-08-01

    Full Text Available To provide layered multicast with responsiveness, efficiency in network utilization, scalability and fairness (including inter-protocol fairness, intra-protocol fairness, intra-session fairness and TCP-friendliness for layered multicast, we propose in this paper a new multicast congestion control, called Explicit Rate Adjustment (ERA. Our protocol uses an algorithm relying on TCP throughput equation and Packet-bunch Probe techniques to detect optimal bandwidth utilization; then adjusts the reception rate accordingly. We have built ERA into a network simulator (ns2 and demonstrate via simulations that the goals are reached.

  5. Impact of visual repetition rate on intrinsic properties of low frequency fluctuations in the visual network.

    Directory of Open Access Journals (Sweden)

    Yi-Chia Li

    Full Text Available BACKGROUND: Visual processing network is one of the functional networks which have been reliably identified to consistently exist in human resting brains. In our work, we focused on this network and investigated the intrinsic properties of low frequency (0.01-0.08 Hz fluctuations (LFFs during changes of visual stimuli. There were two main questions to be discussed in this study: intrinsic properties of LFFs regarding (1 interactions between visual stimuli and resting-state; (2 impact of repetition rate of visual stimuli. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed scanning sessions that contained rest and visual stimuli in various repetition rates with a novel method. The method included three numerical approaches involving ICA (Independent Component Analyses, fALFF (fractional Amplitude of Low Frequency Fluctuation, and Coherence, to respectively investigate the modulations of visual network pattern, low frequency fluctuation power, and interregional functional connectivity during changes of visual stimuli. We discovered when resting-state was replaced by visual stimuli, more areas were involved in visual processing, and both stronger low frequency fluctuations and higher interregional functional connectivity occurred in visual network. With changes of visual repetition rate, the number of areas which were involved in visual processing, low frequency fluctuation power, and interregional functional connectivity in this network were also modulated. CONCLUSIONS/SIGNIFICANCE: To combine the results of prior literatures and our discoveries, intrinsic properties of LFFs in visual network are altered not only by modulations of endogenous factors (eye-open or eye-closed condition; alcohol administration and disordered behaviors (early blind, but also exogenous sensory stimuli (visual stimuli with various repetition rates. It demonstrates that the intrinsic properties of LFFs are valuable to represent physiological states of human brains.

  6. Accelerating Rate Calorimetry Tests of Lithium-Ion Cells Before and After Storage Degradation at High Temperature

    Directory of Open Access Journals (Sweden)

    Mendoza-Hernandez Omar Samuel

    2017-01-01

    Full Text Available Understanding the behavior of Li-ion cells during thermal runaway is critical to evaluate the safety of these energy storage devices under outstanding conditions. Li-ion cells possess a high energy density and are used to store and supply energy to many aerospace applications. Incidents related to the overheating or thermal runaway of these cells can cause catastrophic damages that could end up costly space missions; therefore, thermal studies of Li-ion cells are very important for ensuring safety and reliability of space missions. This work evaluates the thermal behavior of Li-ion cells before and after storage degradation at high temperature using accelerating rate calorimeter (ARC equipment to analyze the thermal behavior of Li-ion cells under adiabatic conditions. Onset temperature points of self-heating and thermal runaway reactions are obtained. The onset points are used to identify non-self-heating, self-heating and thermal runaway regions as a function of state of charge. The results obtained can be useful to develop accurate thermo-electrochemical models of Li-ion cells.

  7. Die degradation effect on aging rate in accelerated cycling tests of SiC power MOSFET modules

    DEFF Research Database (Denmark)

    Luo, Haoze; Baker, Nick; Iannuzzo, Francesco

    2017-01-01

    In order to distinguish the die and bond wire degradations, in this paper both the die and bond wire resistances of SiC MOSFET modules are measured and tested during the accelerated cycling tests. It is proved that, since the die degradation under specific conditions increases the temperature swing...

  8. Degradation of (14)C-labeled few layer graphene via Fenton reaction: Reaction rates, characterization of reaction products, and potential ecological effects.

    Science.gov (United States)

    Feng, Yiping; Lu, Kun; Mao, Liang; Guo, Xiangke; Gao, Shixiang; Petersen, Elijah J

    2015-11-01

    Graphene has attracted considerable commercial interest due to its numerous potential applications. It is inevitable that graphene will be released into the environment during the production and usage of graphene-enabled consumer products, but the potential transformations of graphene in the environment are not well understood. In this study, (14)C-labeled few layer graphene (FLG) enabled quantitative measurements of FLG degradation rates induced by the iron/hydrogen peroxide induced Fenton reaction. Quantification of (14)CO2 production from (14)C-labeled FLG revealed significant degradation of FLG after 3 days with high H2O2 (200 mmol L(-1)) and iron (100 μmol L(-1)) concentrations but substantially lower rates under environmentally relevant conditions (0.2-20 mmol L(-1) H2O2 and 4 μmol L(-1) Fe(3+)). Importantly, the carbon-14 labeling technique allowed for quantification of the FLG degradation rate at concentrations nearly four orders of magnitude lower than those typically used in other studies. These measurements revealed substantially faster degradation rates at lower FLG concentrations and thus studies with higher FLG concentrations may underestimate the degradation rates. Analysis of structural changes to FLG using multiple orthogonal methods revealed significant FLG oxidation and multiple reaction byproducts. Lastly, assessment of accumulation of the degraded FLG and intermediates using aquatic organism Daphnia magna revealed substantially decreased body burdens, which implied that the changes to FLG caused by the Fenton reaction may dramatically impact its potential ecological effects. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Dynamic neural networking as a basis for plasticity in the control of heart rate.

    Science.gov (United States)

    Kember, G; Armour, J A; Zamir, M

    2013-01-21

    A model is proposed in which the relationship between individual neurons within a neural network is dynamically changing to the effect of providing a measure of "plasticity" in the control of heart rate. The neural network on which the model is based consists of three populations of neurons residing in the central nervous system, the intrathoracic extracardiac nervous system, and the intrinsic cardiac nervous system. This hierarchy of neural centers is used to challenge the classical view that the control of heart rate, a key clinical index, resides entirely in central neuronal command (spinal cord, medulla oblongata, and higher centers). Our results indicate that dynamic networking allows for the possibility of an interplay among the three populations of neurons to the effect of altering the order of control of heart rate among them. This interplay among the three levels of control allows for different neural pathways for the control of heart rate to emerge under different blood flow demands or disease conditions and, as such, it has significant clinical implications because current understanding and treatment of heart rate anomalies are based largely on a single level of control and on neurons acting in unison as a single entity rather than individually within a (plastically) interconnected network. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Open-source hardware and software and web application for gamma dose rate network operation.

    Science.gov (United States)

    Luff, R; Zähringer, M; Harms, W; Bleher, M; Prommer, B; Stöhlker, U

    2014-08-01

    The German Federal Office for Radiation Protection operates a network of about 1800 gamma dose rate stations as a part of the national emergency preparedness plan. Each of the six network centres is capable of operating the network alone. Most of the used hardware and software have been developed in-house under open-source license. Short development cycles and close cooperation between developers and users ensure robustness, transparency and fast maintenance procedures, thus avoiding unnecessary complex solutions. This also reduces the overall costs of the network operation. An easy-to-expand web interface has been developed to make the complete system available to other interested network operators in order to increase cooperation between different countries. The interface is also regularly in use for education during scholarships of trainees supported, e.g. by the 'International Atomic Energy Agency' to operate a local area dose rate monitoring test network. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Noise in attractor networks in the brain produced by graded firing rate representations.

    Directory of Open Access Journals (Sweden)

    Tristan J Webb

    Full Text Available Representations in the cortex are often distributed with graded firing rates in the neuronal populations. The firing rate probability distribution of each neuron to a set of stimuli is often exponential or gamma. In processes in the brain, such as decision-making, that are influenced by the noise produced by the close to random spike timings of each neuron for a given mean rate, the noise with this graded type of representation may be larger than with the binary firing rate distribution that is usually investigated. In integrate-and-fire simulations of an attractor decision-making network, we show that the noise is indeed greater for a given sparseness of the representation for graded, exponential, than for binary firing rate distributions. The greater noise was measured by faster escaping times from the spontaneous firing rate state when the decision cues are applied, and this corresponds to faster decision or reaction times. The greater noise was also evident as less stability of the spontaneous firing state before the decision cues are applied. The implication is that spiking-related noise will continue to be a factor that influences processes such as decision-making, signal detection, short-term memory, and memory recall even with the quite large networks found in the cerebral cortex. In these networks there are several thousand recurrent collateral synapses onto each neuron. The greater noise with graded firing rate distributions has the advantage that it can increase the speed of operation of cortical circuitry.

  12. Angular Rate Sensing with GyroWheel Using Genetic Algorithm Optimized Neural Networks.

    Science.gov (United States)

    Zhao, Yuyu; Zhao, Hui; Huo, Xin; Yao, Yu

    2017-07-22

    GyroWheel is an integrated device that can provide three-axis control torques and two-axis angular rate sensing for small spacecrafts. Large tilt angle of its rotor and de-tuned spin rate lead to a complex and non-linear dynamics as well as difficulties in measuring angular rates. In this paper, the problem of angular rate sensing with the GyroWheel is investigated. Firstly, a simplified rate sensing equation is introduced, and the error characteristics of the method are analyzed. According to the analysis results, a rate sensing principle based on torque balance theory is developed, and a practical way to estimate the angular rates within the whole operating range of GyroWheel is provided by using explicit genetic algorithm optimized neural networks. The angular rates can be determined by the measurable values of the GyroWheel (including tilt angles, spin rate and torque coil currents), the weights and the biases of the neural networks. Finally, the simulation results are presented to illustrate the effectiveness of the proposed angular rate sensing method with GyroWheel.

  13. A General Rate K/N Convolutional Decoder Based on Neural Networks with Stopping Criterion

    Directory of Open Access Journals (Sweden)

    Johnny W. H. Kao

    2009-01-01

    Full Text Available A novel algorithm for decoding a general rate K/N convolutional code based on recurrent neural network (RNN is described and analysed. The algorithm is introduced by outlining the mathematical models of the encoder and decoder. A number of strategies for optimising the iterative decoding process are proposed, and a simulator was also designed in order to compare the Bit Error Rate (BER performance of the RNN decoder with the conventional decoder that is based on Viterbi Algorithm (VA. The simulation results show that this novel algorithm can achieve the same bit error rate and has a lower decoding complexity. Most importantly this algorithm allows parallel signal processing, which increases the decoding speed and accommodates higher data rate transmission. These characteristics are inherited from a neural network structure of the decoder and the iterative nature of the algorithm, that outperform the conventional VA algorithm.

  14. Improved constraints on in situ rates and on quantification of complete chloroethene degradation from stable carbon isotope mass balances in groundwater plumes

    Science.gov (United States)

    Höhener, Patrick; Elsner, Martin; Eisenmann, Heinrich; Atteia, Olivier

    2015-11-01

    Spills of chloroethenes (CEs) at industrial and urban sites can create groundwater plumes in which tetrachloro- and trichloroethene sequentially degrade to dichloroethenes, vinyl chloride (VC) and ethene, or ethane under reducing conditions. For detoxification, degradation must go beyond VC. Assessments based on ethene and ethane, however, are difficult because these products are volatile, may stem from alternative sources, can be further transformed and are not always monitored. To alternatively quantify degradation beyond VC, stable carbon isotope mass balances have been proposed where concentration-weighted CE isotope ratios are summed up and compared to the original source isotope ratio. Reported assessments, however, have provided not satisfactorily quantified results entailing greatly differing upper and lower estimates. This work proposes an integrative approach to better constrain the extent of total chloroethene degradation in groundwater samples. It is based on fitting of measured concentration and compound-specific stable carbon isotope data to an analytical reactive transport equation simulating steady-state plumes in two dimensions using an EXCEL spreadsheet. The fitting also yields estimates of degradation rates, of source width and of dispersivities. The approach is validated using two synthetic benchmark cases where the true extent of degradation is well known, and using data from two real field cases from literature.

  15. Modeling and Model Predictive Power and Rate Control of Wireless Communication Networks

    Directory of Open Access Journals (Sweden)

    Cunwu Han

    2014-01-01

    Full Text Available A novel power and rate control system model for wireless communication networks is presented, which includes uncertainties, input constraints, and time-varying delays in both state and control input. A robust delay-dependent model predictive power and rate control method is proposed, and the state feedback control law is obtained by solving an optimization problem that is derived by using linear matrix inequality (LMI techniques. Simulation results are given to illustrate the effectiveness of the proposed method.

  16. Packetized Predictive Control for Rate-Limited Networks via Sparse Representation

    DEFF Research Database (Denmark)

    Nagahara, Masaaki; Quevedo, Daniel; Østergaard, Jan

    2012-01-01

    controller and the plant input. To achieve robustness with respect to dropouts, the controller transmits data packets containing plant input predictions, which minimize a finite horizon cost function. In our formulation, we design sparse packets for rate-limited networks, by adopting an an ℓ0 optimization...

  17. Training a multilayer neural network for the Euro-dollar (EUR/ USD) exchange rate

    National Research Council Canada - National Science Library

    Jaime Alberto Villamil Torres; Jesús Alberto Delgado Rivera

    2010-01-01

    ... (as first approximation) a random walk. This paper reports the results of using ANNs for Euro/USD exchange rate trading and the usefulness of the algorithm for chemotaxis leading to training networks thereby maximising an objective function re predicting a trader’s profits. JEL: F310, C450.

  18. The association between social networks and self-rated risk of HIV ...

    African Journals Online (AJOL)

    This study describes the social networks of secondary school students in Moshi Municipality, and their association with self-rated risk of human immunodeficiency virus (HIV) infection. A cross-sectional analytical study was conducted among 300 students aged 15–24 years in 5 secondary schools in Moshi, Tanzania.

  19. Choosing optimum noise figure and data rate in wireless sensor network radio transceivers

    NARCIS (Netherlands)

    Dutta, R.; van der Zee, Ronan A.R.; Bentum, Marinus Jan; Kokkeler, Andre B.J.

    2011-01-01

    To reduce the energy consumption in wireless sensor network transceivers, we propose an approach which combines two tradeoffs. The first tradeoff is between the receiver sensitivity and transmitter output power. The second one is the duty cycle and data rate of the transceiver. The combined approach

  20. The interchangeability of learning rate and gain in backpropagation neural networks

    NARCIS (Netherlands)

    Thimm, G.; Moerland, P.; Fiesler, E.

    1996-01-01

    The backpropagation algorithm is widely used for training multilayer neural networks. In this publication the gain of its activation function(s) is investigated. In specific, it is proven that changing the gain of the activation function is equivalent to changing the learning rate and the weights.

  1. Estimation of mutation rates from paternity cases using a Bayesian network

    DEFF Research Database (Denmark)

    Vicard, P.; Dawid, A.P.; Mortera, J.

    and paternal mutation rates, while allowing a wide variety of mutation models. A Bayesian network is constructed to facilitate computation of the likelihood function for the mutation parameters. It can process both full and summary genotypic information, from both complete putative father-mother-child triplets...

  2. Depression and unemployment incidence rate evolution in Portugal, 1995-2013: General Practitioner Sentinel Network data.

    Science.gov (United States)

    Rodrigues, Ana Paula; Sousa-Uva, Mafalda; Fonseca, Rita; Marques, Sara; Pina, Nuno; Matias-Dias, Carlos

    2017-11-17

    Quantify, for both genders, the correlation between the depression incidence rate and the unemployment rate in Portugal between 1995 and 2013. An ecological study was developed to correlate the evolution of the depression incidence rates estimated by the General Practitioner Sentinel Network and the annual unemployment rates provided by the National Statistical Institute in official publications. There was a positive correlation between the depression incidence rate and the unemployment rate in Portugal, which was significant only for males (R2 = 0.83, p = 0.04). For this gender, an increase of 37 new cases of depression per 100,000 inhabitants was estimated for each 1% increase in the unemployment rate between 1995 and 2013. Although the study design does not allow the establishment of a causal association between unemployment and depression, the results suggest that the evolution of unemployment in Portugal may have had a significant impact on the level of mental health of the Portuguese, especially among men.

  3. Impact of dynamic rate coding aspects of mobile phone networks on forensic voice comparison.

    Science.gov (United States)

    Alzqhoul, Esam A S; Nair, Balamurali B T; Guillemin, Bernard J

    2015-09-01

    Previous studies have shown that landline and mobile phone networks are different in their ways of handling the speech signal, and therefore in their impact on it. But the same is also true of the different networks within the mobile phone arena. There are two major mobile phone technologies currently in use today, namely the global system for mobile communications (GSM) and code division multiple access (CDMA) and these are fundamentally different in their design. For example, the quality of the coded speech in the GSM network is a function of channel quality, whereas in the CDMA network it is determined by channel capacity (i.e., the number of users sharing a cell site). This paper examines the impact on the speech signal of a key feature of these networks, namely dynamic rate coding, and its subsequent impact on the task of likelihood-ratio-based forensic voice comparison (FVC). Surprisingly, both FVC accuracy and precision are found to be better for both GSM- and CDMA-coded speech than for uncoded. Intuitively one expects FVC accuracy to increase with increasing coded speech quality. This trend is shown to occur for the CDMA network, but, surprisingly, not for the GSM network. Further, in respect to comparisons between these two networks, FVC accuracy for CDMA-coded speech is shown to be slightly better than for GSM-coded speech, particularly when the coded-speech quality is high, but in terms of FVC precision the two networks are shown to be very similar. Copyright © 2015 The Chartered Society of Forensic Sciences. Published by Elsevier Ireland Ltd. All rights reserved.

  4. CRRT: Congestion-Aware and Rate-Controlled Reliable Transport in Wireless Sensor Networks

    Science.gov (United States)

    Alam, Muhammad Mahbub; Hong, Choong Seon

    For successful data collection in wireless sensor networks, it is important to ensure that the required delivery ratio is maintained while keeping a fair rate for every sensor. Furthermore, emerging high-rate applications might require complete reliability and the transfer of large volume of data, where persistent congestion might occur. These requirements demand a complete but efficient solution for data transport in sensor networks which reliably transports data from many sources to one or more sinks, avoids congestion and maintains fairness. In this paper, we propose congestion-aware and rate-controlled reliable transport (CRRT), an efficient and low-overhead data transport mechanism for sensor networks. CRRT uses efficient MAC retransmission to increase one-hop reliability and end-to-end retransmission for loss recovery. It also controls the total rate of the sources centrally, avoids the congestion in the bottleneck based on congestion notifications from intermediate nodes and centrally assigns the rate to the sources based on rate assignment policy of the applications. Performance of CRRT is evaluated in NS-2 and simulation results demonstrate the effectiveness of CRRT.

  5. Tuning the Degradation Rate of Calcium Phosphate Cements by Incorporating Mixtures of Polylactic-co-Glycolic Acid Microspheres and Glucono-Delta-Lactone Microparticles

    NARCIS (Netherlands)

    Sariibrahimoglu, K.; An, J.; Oirschot, B.A.J.A. van; Nijhuis, A.W.G.; Eman, R.M.; Alblas, J.; Wolke, J.G.C.; Beucken, J.J.J.P van den; Leeuwenburgh, S.C.G.; Jansen, J.A.

    2014-01-01

    Calcium phosphate cements (CPCs) are frequently used as synthetic bone graft materials in view of their excellent osteocompatibility and clinical handling behavior. Hydroxyapatite-forming CPCs, however, degrade at very low rates, thereby limiting complete bone regeneration. The current study has

  6. Fine-Grained Rate Shaping for Video Streaming over Wireless Networks

    Directory of Open Access Journals (Sweden)

    Chen Tsuhan

    2004-01-01

    Full Text Available Video streaming over wireless networks faces challenges of time-varying packet loss rate and fluctuating bandwidth. In this paper, we focus on streaming precoded video that is both source and channel coded. Dynamic rate shaping has been proposed to “shape” the precompressed video to adapt to the fluctuating bandwidth. In our earlier work, rate shaping was extended to shape the channel coded precompressed video, and to take into account the time-varying packet loss rate as well as the fluctuating bandwidth of the wireless networks. However, prior work on rate shaping can only adjust the rate oarsely. In this paper, we propose “fine-grained rate shaping (FGRS” to allow for bandwidth adaptation over a wide range of bandwidth and packet loss rate in fine granularities. The video is precoded with fine granularity scalability (FGS followed by channel coding. Utilizing the fine granularity property of FGS and channel coding, FGRS selectively drops part of the precoded video and still yields decodable bit-stream at the decoder. Moreover, FGRS optimizes video streaming rather than achieves heuristic objectives as conventional methods. A two-stage rate-distortion (RD optimization algorithm is proposed for FGRS. Promising results of FGRS are shown.

  7. Controlling the degradation rate of AZ91 magnesium alloy via sol–gel derived nanostructured hydroxyapatite coating

    Energy Technology Data Exchange (ETDEWEB)

    Rojaee, Ramin, E-mail: raminrojaee@aim.com [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Raeissi, Keyvan [Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of)

    2013-10-15

    Magnesium (Mg) alloys have been introduced as new generation of biodegradable orthopedic materials in recent years since it has been proved that Mg is one of the main minerals required for osseous tissue revival. The main goal of the present study was to establish a desired harmony between the necessities of orthopedic patient body to Mg{sup 2+} ions and degradation rate of the Mg based implants as a new class of biodegradable/bioresorbable materials. This prospect was followed by providing a sol–gel derived nanostructured hydroxyapatite (n-HAp) coating on AZ91 alloy using dip coating technique. Phase structural analysis, morphology study, microstructure characterization, and functional group identification were performed using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The prepared samples were immersed in simulated body fluid in order to study the formation of apatite-like precipitations, barricade properties of the n-HAp coating, and to estimate the dosage of released Mg{sup 2+} ions within a specified and limited time of implantation. Electrochemical polarization tests were carried out to evaluate and compare the corrosion behavior of the n-HAp coated and uncoated samples. The changes of the in vitro pH values were also evaluated. Results posed the noticeable capability of n-HAp coating on stabilizing alkalization behavior and improving the corrosion resistance of AZ91 alloy. It was concluded that n-HAp coated AZ91 alloy could be a good candidate as a type of biodegradable implant material for biomedical applications. - Highlights: • Nanostructured hydroxyapatite coatings were applied on Mg based alloy. • The whole corrosion process of Mg based alloy was controlled in body fluid. • This coating was able to act as a barrier against further release of Mg{sup 2+} ions. • The coating improved the stabilization of Mg alkalization behavior.

  8. Balancing the rates of new bone formation and polymer degradation enhances healing of weight-bearing allograft/polyurethane composites in rabbit femoral defects.

    Science.gov (United States)

    Dumas, Jerald E; Prieto, Edna M; Zienkiewicz, Katarzyna J; Guda, Teja; Wenke, Joseph C; Bible, Jesse; Holt, Ginger E; Guelcher, Scott A

    2014-01-01

    There is a compelling clinical need for bone grafts with initial bone-like mechanical properties that actively remodel for repair of weight-bearing bone defects, such as fractures of the tibial plateau and vertebrae. However, there is a paucity of studies investigating remodeling of weight-bearing bone grafts in preclinical models, and consequently there is limited understanding of the mechanisms by which these grafts remodel in vivo. In this study, we investigated the effects of the rates of new bone formation, matrix resorption, and polymer degradation on healing of settable weight-bearing polyurethane/allograft composites in a rabbit femoral condyle defect model. The grafts induced progressive healing in vivo, as evidenced by an increase in new bone formation, as well as a decrease in residual allograft and polymer from 6 to 12 weeks. However, the mismatch between the rates of autocatalytic polymer degradation and zero-order (independent of time) new bone formation resulted in incomplete healing in the interior of the composite. Augmentation of the grafts with recombinant human bone morphogenetic protein-2 not only increased the rate of new bone formation, but also altered the degradation mechanism of the polymer to approximate a zero-order process. The consequent matching of the rates of new bone formation and polymer degradation resulted in more extensive healing at later time points in all regions of the graft. These observations underscore the importance of balancing the rates of new bone formation and degradation to promote healing of settable weight-bearing bone grafts that maintain bone-like strength, while actively remodeling.

  9. Intelligent Soft Computing on Forex: Exchange Rates Forecasting with Hybrid Radial Basis Neural Network

    Directory of Open Access Journals (Sweden)

    Lukas Falat

    2016-01-01

    Full Text Available This paper deals with application of quantitative soft computing prediction models into financial area as reliable and accurate prediction models can be very helpful in management decision-making process. The authors suggest a new hybrid neural network which is a combination of the standard RBF neural network, a genetic algorithm, and a moving average. The moving average is supposed to enhance the outputs of the network using the error part of the original neural network. Authors test the suggested model on high-frequency time series data of USD/CAD and examine the ability to forecast exchange rate values for the horizon of one day. To determine the forecasting efficiency, they perform a comparative statistical out-of-sample analysis of the tested model with autoregressive models and the standard neural network. They also incorporate genetic algorithm as an optimizing technique for adapting parameters of ANN which is then compared with standard backpropagation and backpropagation combined with K-means clustering algorithm. Finally, the authors find out that their suggested hybrid neural network is able to produce more accurate forecasts than the standard models and can be helpful in eliminating the risk of making the bad decision in decision-making process.

  10. Intelligent Soft Computing on Forex: Exchange Rates Forecasting with Hybrid Radial Basis Neural Network.

    Science.gov (United States)

    Falat, Lukas; Marcek, Dusan; Durisova, Maria

    2016-01-01

    This paper deals with application of quantitative soft computing prediction models into financial area as reliable and accurate prediction models can be very helpful in management decision-making process. The authors suggest a new hybrid neural network which is a combination of the standard RBF neural network, a genetic algorithm, and a moving average. The moving average is supposed to enhance the outputs of the network using the error part of the original neural network. Authors test the suggested model on high-frequency time series data of USD/CAD and examine the ability to forecast exchange rate values for the horizon of one day. To determine the forecasting efficiency, they perform a comparative statistical out-of-sample analysis of the tested model with autoregressive models and the standard neural network. They also incorporate genetic algorithm as an optimizing technique for adapting parameters of ANN which is then compared with standard backpropagation and backpropagation combined with K-means clustering algorithm. Finally, the authors find out that their suggested hybrid neural network is able to produce more accurate forecasts than the standard models and can be helpful in eliminating the risk of making the bad decision in decision-making process.

  11. Max-Min Optimality of Service Rate Control in Closed Queueing Networks

    KAUST Repository

    Xia, Li

    2013-04-01

    In this technical note, we discuss the optimality properties of service rate control in closed Jackson networks. We prove that when the cost function is linear to a particular service rate, the system performance is monotonic w.r.t. (with respect to) that service rate and the optimal value of that service rate can be either maximum or minimum (we call it Max-Min optimality); When the second-order derivative of the cost function w.r.t. a particular service rate is always positive (negative), which makes the cost function strictly convex (concave), the optimal value of such service rate for the performance maximization (minimization) problem can be either maximum or minimum. To the best of our knowledge, this is the most general result for the optimality of service rates in closed Jackson networks and all the previous works only involve the first conclusion. Moreover, our result is also valid for both the state-dependent and load-dependent service rates, under both the time-average and customer-average performance criteria.

  12. Hopfield neural network and optical fiber sensor as intelligent heart rate monitor

    Science.gov (United States)

    Mutter, Kussay Nugamesh

    2018-01-01

    This paper presents a design and fabrication of an intelligent fiber-optic sensor used for examining and monitoring heart rate activity. It is found in the literature that the use of fiber sensors as heart rate sensor is widely studied. However, the use of smart sensors based on Hopfield neural networks is very low. In this work, the sensor is a three fibers without cladding of about 1 cm, fed by laser light of 1550 nm of wavelength. The sensing portions are mounted with a micro sensitive diaphragm to transfer the pulse pressure on the left radial wrist. The influenced light intensity will be detected by a three photodetectors as inputs into the Hopfield neural network algorithm. The latter is a singlelayer auto-associative memory structure with a same input and output layers. The prior training weights are stored in the net memory for the standard recorded normal heart rate signals. The sensors' heads work on the reflection intensity basis. The novelty here is that the sensor uses a pulse pressure and Hopfield neural network in an integrity approach. The results showed a significant output measurements of heart rate and counting with a plausible error rate.

  13. Topological quantum computing with a very noisy network and local error rates approaching one percent.

    Science.gov (United States)

    Nickerson, Naomi H; Li, Ying; Benjamin, Simon C

    2013-01-01

    A scalable quantum computer could be built by networking together many simple processor cells, thus avoiding the need to create a single complex structure. The difficulty is that realistic quantum links are very error prone. A solution is for cells to repeatedly communicate with each other and so purify any imperfections; however prior studies suggest that the cells themselves must then have prohibitively low internal error rates. Here we describe a method by which even error-prone cells can perform purification: groups of cells generate shared resource states, which then enable stabilization of topologically encoded data. Given a realistically noisy network (≥10% error rate) we find that our protocol can succeed provided that intra-cell error rates for initialisation, state manipulation and measurement are below 0.82%. This level of fidelity is already achievable in several laboratory systems.

  14. Nash Equilibrium of an Energy Saving Strategy with Dual Rate Transmission in Wireless Regional Area Network

    Directory of Open Access Journals (Sweden)

    Zhanqiang Huo

    2017-01-01

    Full Text Available Wireless regional area network (WRAN adopts centralized network architecture and is currently one of the most typical cognitive radio networks. In order to reduce the energy consumption of the communication networks with the constraint of spectrum resource utilization, a working sleep mechanism is introduced into the base station (BS, and a novel energy saving strategy with dual rate transmission is proposed. Combining the multiple-vacation queue and priority queue, using the quasi-birth-death process and the matrix-geometric solution method, we assess the average latency and the forced termination probability of secondary user packets, as well as the energy saving ratio and the channel utilization of system. Based on the revenue-expenditure structure, a profit function is built, and then the Nash equilibrium behavior and the socially optimal behavior are investigated. With the help of the particle swarm optimization, an intelligent optimization algorithm to search the socially optimal arrival rate of secondary user packets is presented. In order to unify the arrival rates of secondary user packets with Nash equilibrium and social optimization, a reasonable pricing policy is formulated. In addition, system experiments are carried out to verify the effectiveness of the energy saving strategy and the rationality of the pricing policy.

  15. Cognitive Multiple-Antenna Network with Outage and Rate Margins at the Primary System

    DEFF Research Database (Denmark)

    Maham, Behrouz; Popovski, Petar

    2015-01-01

    for the primary base station (BS): space-time coding, antenna selection, and beamforming, each of them with different channel information requirements. We first consider the case in which the primary BS uses a fixed rate and we analyze the outage probability. In high-SNR scenario, we derive closed-form asymptotic...... BS and introduce a suitable rate margin and a consistent requirement for primary throughput, for which we determine the outage probability. To be able to accommodate the secondary network, a rate margin is assumed at the primary link. We calculate the exact outage probabilities and average throughput...

  16. Power consumption analysis of constant bit rate video transmission over 3G networks

    DEFF Research Database (Denmark)

    Ukhanova, Ann; Belyaev, Evgeny; Wang, Le

    2012-01-01

    This paper presents an analysis of the power consumption of video data transmission with constant bit rate over 3G mobile wireless networks. The work includes the description of the radio resource control transition state machine in 3G networks, followed by a detailed power consumption analysis...... for the 3GPP transition state machine that allows to decrease power consumption on a mobile device taking signaling traffic, buffer size and latency restrictions into account. Furthermore, we discuss the gain in power consumption vs. PSNR for transmitted video and show the possibility of performing power...... consumption management based on the requirements for the video quality....

  17. Power consumption analysis of constant bit rate data transmission over 3G mobile wireless networks

    DEFF Research Database (Denmark)

    Wang, Le; Ukhanova, Ann; Belyaev, Evgeny

    2011-01-01

    This paper presents the analysis of the power consumption of data transmission with constant bit rate over 3G mobile wireless networks. Our work includes the description of the transition state machine in 3G networks, followed by the detailed energy consumption analysis and measurement results...... of the radio link power consumption. Based on these description and analysis, we propose power consumption model. The power model was evaluated on the smartphone Nokia N900, which follows a 3GPP Release 5 and 6 supporting HSDPA/HSPA data bearers. Further we propose method of parameters selection for 3GPP...... transition state machine that allows to decrease power consumption on the mobile device....

  18. Residue Geometry Networks: A Rigidity-Based Approach to the Amino Acid Network and Evolutionary Rate Analysis

    Science.gov (United States)

    Fokas, Alexander S.; Cole, Daniel J.; Ahnert, Sebastian E.; Chin, Alex W.

    2016-09-01

    Amino acid networks (AANs) abstract the protein structure by recording the amino acid contacts and can provide insight into protein function. Herein, we describe a novel AAN construction technique that employs the rigidity analysis tool, FIRST, to build the AAN, which we refer to as the residue geometry network (RGN). We show that this new construction can be combined with network theory methods to include the effects of allowed conformal motions and local chemical environments. Importantly, this is done without costly molecular dynamics simulations required by other AAN-related methods, which allows us to analyse large proteins and/or data sets. We have calculated the centrality of the residues belonging to 795 proteins. The results display a strong, negative correlation between residue centrality and the evolutionary rate. Furthermore, among residues with high closeness, those with low degree were particularly strongly conserved. Random walk simulations using the RGN were also successful in identifying allosteric residues in proteins involved in GPCR signalling. The dynamic function of these residues largely remain hidden in the traditional distance-cutoff construction technique. Despite being constructed from only the crystal structure, the results in this paper suggests that the RGN can identify residues that fulfil a dynamical function.

  19. Atmospheric reactions of methylcyclohexanes with Cl atoms and OH radicals: determination of rate coefficients and degradation products.

    Science.gov (United States)

    Ballesteros, Bernabé; Ceacero-Vega, Antonio A; Jiménez, Elena; Albaladejo, José

    2015-04-01

    mechanism for ring-retaining product channels is proposed to justify the observed reaction products. The global tropospheric lifetimes estimated from the reported OH- and Cl-rate coefficients show that the main removal path for the investigated methylcyclohexanes is the reaction with OH radicals. But in marine environments, after sunrise, Cl reactions become more important in the tropospheric degradation. Thus, the estimated lifetimes range from 16 to 24 h for the reactions of the OH radical (calculated with [OH] = 10(6) atoms cm(-3)) and around 7-8 h in the reactions with Cl atoms in marine environments (calculated with [Cl] = 1.3 × 10(5) atoms cm(-3)). The reaction of Cl atoms and OH radicals and methylcylohexanes can proceed by H abstraction from the different positions.

  20. A Geometric Method for Model Reduction of Biochemical Networks with Polynomial Rate Functions.

    Science.gov (United States)

    Samal, Satya Swarup; Grigoriev, Dima; Fröhlich, Holger; Weber, Andreas; Radulescu, Ovidiu

    2015-12-01

    Model reduction of biochemical networks relies on the knowledge of slow and fast variables. We provide a geometric method, based on the Newton polytope, to identify slow variables of a biochemical network with polynomial rate functions. The gist of the method is the notion of tropical equilibration that provides approximate descriptions of slow invariant manifolds. Compared to extant numerical algorithms such as the intrinsic low-dimensional manifold method, our approach is symbolic and utilizes orders of magnitude instead of precise values of the model parameters. Application of this method to a large collection of biochemical network models supports the idea that the number of dynamical variables in minimal models of cell physiology can be small, in spite of the large number of molecular regulatory actors.

  1. Low Duty-Cycling MAC Protocol for Low Data-Rate Medical Wireless Body Area Networks

    Directory of Open Access Journals (Sweden)

    Chongqing Zhang

    2017-05-01

    Full Text Available Wireless body area networks (WBANs are severely energy constrained, and how to improve the energy efficiency so as to prolong the network lifetime as long as possible is one of the most important goals of WBAN research. Low data-rate WBANs are promising to cut down the energy consumption and extend the network lifetime. Considering the characteristics and demands of low data-rate WBANs, a low duty-cycling medium access control (MAC protocol is specially designed for this kind of WBAN in this paper. Longer superframes are exploited to cut down the energy consumed on the transmissions and receptions of redundant beacon frames. Insertion time slots are embedded into the inactive part of a superframe to deliver the frames and satisfy the quality of service (QoS requirements. The number of the data subsections in an insertion time slot can be adaptively adjusted so as to accommodate low data-rate WBANs with different traffic. Simulation results show that the proposed MAC protocol performs well under the condition of low data-rate monitoring traffic.

  2. Time-Efficient High-Rate Data Flooding in One-Dimensional Acoustic Underwater Sensor Networks

    Directory of Open Access Journals (Sweden)

    Jae Kyun Kwon

    2015-10-01

    Full Text Available Because underwater communication environments have poor characteristics, such as severe attenuation, large propagation delays and narrow bandwidths, data is normally transmitted at low rates through acoustic waves. On the other hand, as high traffic has recently been required in diverse areas, high rate transmission has become necessary. In this paper, transmission/reception timing schemes that maximize the time axis use efficiency to improve the resource efficiency for high rate transmission are proposed. The excellence of the proposed scheme is identified by examining the power distributions by node, rate bounds, power levels depending on the rates and number of nodes, and network split gains through mathematical analysis and numerical results. In addition, the simulation results show that the proposed scheme outperforms the existing packet train method.

  3. Dialysis Facility and Network Factors Associated With Low Kidney Transplantation Rates Among United States Dialysis Facilities

    Science.gov (United States)

    Patzer, R. E.; Plantinga, L.; Krisher, J.; Pastan, S. O.

    2014-01-01

    Variability in transplant rates between different dialysis units has been noted, yet little is known about facility-level factors associated with low standardized transplant ratios (STRs) across the United States End-stage Renal Disease (ESRD) Network regions. We analyzed Centers for Medicare & Medicaid Services Dialysis Facility Report data from 2007 to 2010 to examine facility-level factors associated with low STRs using multivariable mixed models. Among 4098 dialysis facilities treating 305 698 patients, there was wide variability in facility-level STRs across the 18 ESRD Networks. Four-year average STRs ranged from 0.69 (95% confidence interval [CI]: 0.64–0.73) in Network 6 (Southeastern Kidney Council) to 1.61 (95% CI: 1.47–1.76) in Network 1 (New England). Factors significantly associated with a lower STR (p dialysis were associated with higher STRs. The lowest performing dialysis facilities were in the Southeastern United States. Understanding the modifiable facility-level factors associated with low transplant rates may inform interventions to improve access to transplantation. PMID:24891272

  4. Data Aggregation Based on Overlapping Rate of Sensing Area in Wireless Sensor Networks.

    Science.gov (United States)

    Tang, Xiaolan; Xie, Hua; Chen, Wenlong; Niu, Jianwei; Wang, Shuhang

    2017-06-29

    Wireless sensor networks are required in smart applications to provide accurate control, where the high density of sensors brings in a large quantity of redundant data. In order to reduce the waste of limited network resources, data aggregation is utilized to avoid redundancy forwarding. However, most of aggregation schemes reduce information accuracy and prolong end-to-end delay when eliminating transmission overhead. In this paper, we propose a data aggregation scheme based on overlapping rate of sensing area, namely AggOR, aiming for energy-efficient data collection in wireless sensor networks with high information accuracy. According to aggregation rules, gathering nodes are selected from candidate parent nodes and appropriate neighbor nodes considering a preset threshold of overlapping rate of sensing area. Therefore, the collected data in a gathering area are highly correlated, and a large amount of redundant data could be cleaned. Meanwhile, AggOR keeps the original entropy by only deleting the duplicated data. Experiment results show that compared with others, AggOR has a high data accuracy and a short end-to-end delay with a similar network lifetime.

  5. Using dynamic line rating to minimize curtailment of wind power connected to rural power networks

    Energy Technology Data Exchange (ETDEWEB)

    Schell, Peter [Ampacimon SA, Angleur (Belgium); Lambin, Jean-Jacques [Elia, Brussels (Belgium); Godard, Bertrand; Nguyen, Huu-Minh; Lilien, J.L. [Liege Univ. (Belgium). ULG Montefiore Inst.

    2011-07-01

    Elia, the Belgian TSO, is aiming to minimize curtailment of wind power plants connected to its 70kV rural network to the absolute minimum by using Dynamic Line Rating in combination with advanced flow simulation. This combination allows Elia to use its network assets to their real time maximum, without increasing risk and decreasing the security of supply. In situations like the one described below, where it's possible to control the flow in near real-time via curtailment it becomes possible to use all of the extra capacity available via Dynamic Line Rating. On average more then 30% extra capacity is available but this figure can easily increase to 100% extra capacity as soon as there is more than 4 m/s wind perpendicular to the line. (orig.)

  6. Recursive Estimation for Dynamical Systems with Different Delay Rates Sensor Network and Autocorrelated Process Noises

    Directory of Open Access Journals (Sweden)

    Jianxin Feng

    2014-01-01

    Full Text Available The recursive estimation problem is studied for a class of uncertain dynamical systems with different delay rates sensor network and autocorrelated process noises. The process noises are assumed to be autocorrelated across time and the autocorrelation property is described by the covariances between different time instants. The system model under consideration is subject to multiplicative noises or stochastic uncertainties. The sensor delay phenomenon occurs in a random way and each sensor in the sensor network has an individual delay rate which is characterized by a binary switching sequence obeying a conditional probability distribution. By using the orthogonal projection theorem and an innovation analysis approach, the desired recursive robust estimators including recursive robust filter, predictor, and smoother are obtained. Simulation results are provided to demonstrate the effectiveness of the proposed approaches.

  7. Training a multilayer neural network for the Euro-dollar (EUR/ USD exchange rate

    Directory of Open Access Journals (Sweden)

    Jaime Alberto Villamil Torres

    2010-04-01

    Full Text Available A mathematical tool or model for predicting how an economic variable like the exchange rate (relative price between two currencies will respond is a very important need for investors and policy-makers. Most current techniques are based on statistics, particularly linear time series theory. Artificial neural networks (ANNs are mathematical models which try to emulate biological neural networks’ parallelism and nonlinearity; these models have been successfully applied in Economics and Engineering since the 1980s. ANNs appear to be an alternative for modelling the behaviour of financial variables which resemble (as first approximation a random walk. This paper reports the results of using ANNs for Euro/USD exchange rate trading and the usefulness of the algorithm for chemotaxis leading to training networks thereby maximising an objective function re predicting a trader’s profits. JEL: F310, C450.

  8. Automatic optimisation of gamma dose rate sensor networks: The DETECT Optimisation Tool

    DEFF Research Database (Denmark)

    Helle, K.B.; Müller, T.O.; Astrup, Poul

    2014-01-01

    Fast delivery of comprehensive information on the radiological situation is essential for decision-making in nuclear emergencies. Most national radiological agencies in Europe employ gamma dose rate sensor networks to monitor radioactive pollution of the atmosphere. Sensor locations were often ch....... The DOT runs on a server and can be accessed via common web browsers; it can also be installed locally. © 2014 Elsevier Ltd. All rights reserved...

  9. A Double Rate Localization Algorithm with One Anchor for Multi-Hop Underwater Acoustic Networks.

    Science.gov (United States)

    Gao, Jingjie; Shen, Xiaohong; Zhao, Ruiqin; Mei, Haodi; Wang, Haiyan

    2017-04-28

    Localization is a basic issue for underwater acoustic networks (UANs). Currently, most localization algorithms only perform well in one-hop networks or need more anchors which are not suitable for the underwater environment. In this paper, we proposed a double rate localization algorithm with one anchor for multi-hop underwater acoustic networks (DRL). The algorithm firstly presents a double rate scheme which separates the localization procedure into two modes to increase the ranging accuracy in multi-hop UANs while maintaining the transmission rate. Then an optimal selection scheme of reference nodes was proposed to reduce the influence of references' topology on localization performance. The proposed DRL algorithm can be used in the multi-hop UANs to increase the localization accuracy and reduce the usage of anchor nodes. The simulation and experimental results demonstrated that the proposed DRL algorithm has a better localization performance than the previous algorithms in many aspects such as accuracy and communication cost, and is more suitable to the underwater environment.

  10. A method to estimate emission rates from industrial stacks based on neural networks.

    Science.gov (United States)

    Olcese, Luis E; Toselli, Beatriz M

    2004-11-01

    This paper presents a technique based on artificial neural networks (ANN) to estimate pollutant rates of emission from industrial stacks, on the basis of pollutant concentrations measured on the ground. The ANN is trained on data generated by the ISCST3 model, widely accepted for evaluation of dispersion of primary pollutants as a part of an environmental impact study. Simulations using theoretical values and comparison with field data are done, obtaining good results in both cases at predicting emission rates. The application of this technique would allow the local environment authority to control emissions from industrial plants without need of performing direct measurements inside the plant. copyright 2004 Elsevier Ltd.

  11. Water Absorption Rate Prediction of PMMA and Its Composites Using BP Neural Network

    Directory of Open Access Journals (Sweden)

    Chen Kui

    2016-01-01

    Full Text Available Referring to water absorption rate of poly (methyl methacrylate (PMMA and its composites is hard to obtain under some working conditions, BP neural network prediction model was constructed. Regarding water absorption rate predictions of exfoliated PMMA/MMT nanocomposites in 0.1 mol/L H2SO4 solution, 0.1 mol/L NaOH solution and deionized water respectively as examples, the applicability of model established in water absorption rate prediction of PMMA and its composites was researched. The results show that the relative errors between prediction value obtained from model established and actual value of water absorption rate of composites soaking 63min in three kinds of mediums are 1.50%, 0.47% and 1.04% respectively, prediction accuracy is higher than that (relative errors are 3.89%, 3.40% and 4.43% respectively obtained from GM (1, 1 model obviously. BP neural network can be used to predict water absorption rate of PMMA and its composites.

  12. Tuning the degradation rate of calcium phosphate cements by incorporating mixtures of polylactic-co-glycolic acid microspheres and glucono-delta-lactone microparticles.

    Science.gov (United States)

    Sariibrahimoglu, Kemal; An, Jie; van Oirschot, Bart A J A; Nijhuis, Arnold W G; Eman, Rhandy M; Alblas, Jacqueline; Wolke, Joop G C; van den Beucken, Jeroen J J P; Leeuwenburgh, Sander C G; Jansen, John A

    2014-11-01

    Calcium phosphate cements (CPCs) are frequently used as synthetic bone graft materials in view of their excellent osteocompatibility and clinical handling behavior. Hydroxyapatite-forming CPCs, however, degrade at very low rates, thereby limiting complete bone regeneration. The current study has investigated whether degradation of apatite-forming cements can be tuned by incorporating acid-producing slow-resorbing poly(D,L-lactic-co-glycolic) acid (PLGA) porogens, fast-resorbing glucono-delta-lactone (GDL) porogens, or mixtures thereof. The physicochemical, mechanical, and degradation characteristics of these CPC formulations were systematically analyzed upon soaking in phosphate-buffered saline (PBS). In parallel, various CPC formulations were implanted intramuscularly and orthotopically on top of the transverse process of goats followed by analysis of the soft tissue response and bone ingrowth after 12 weeks. In vitro degradation of GDL was almost completed after 2 weeks, as evidenced by characterization of the release of gluconic acid, while PLGA-containing CPCs released glycolic acid throughout the entire study (12 weeks), resulting in a decrease in compression strength of CPC. Extensive in vitro degradation of the CPC matrix was observed upon simultaneous incorporation of 30% PLGA-10% GDL. Histomorphometrical evaluation of the intramuscularly implanted samples revealed that all CPCs exhibited degradation, accompanied by an increase in capsule thickness. In the in vivo goat transverse process model, incorporation of 43% PLGA, 30% PLGA-5% GDL, and 30% PLGA-10% GDL in CPC significantly increased bone formation and resulted in higher bone height compared with both 10% GDL and 20% GDL-containing CPC samples.

  13. A Energy-Saving Path-Shared Protection Based on Diversity Network Coding for Multi-rate Multicast in WDM Mesh Networks

    Science.gov (United States)

    Zheng, Danling; Lv, Lei; Liu, Huanlin

    2017-08-01

    For improving the survivability and energy saving of multi-rate multicast, a novel energy-saving path-shared protection based on diversity network coding (EPP-DNC) for multi-rate multicast in wavelength division multiplexing (WDM) mesh networks is proposed in the paper. In the EPP-DNC algorithm, diversity network coding on the source node for multi-rate multicast is adopted to reduce the coding energy consumption by avoiding network coding on the network's intermediate nodes. To decrease the transmission energy, shortest path shared based on heuristic is proposed to transmit the protection information for the request. To provision request's working paths efficiency, the working paths are routed on the preselected P-cycles with minimum required links and minimum energy consumption. Simulation results show that the proposed EPP-DNC can save energy consumption and improve bandwidth utilization.

  14. Bringing metabolic networks to life: convenience rate law and thermodynamic constraints

    Directory of Open Access Journals (Sweden)

    Klipp Edda

    2006-12-01

    Full Text Available Abstract Background Translating a known metabolic network into a dynamic model requires rate laws for all chemical reactions. The mathematical expressions depend on the underlying enzymatic mechanism; they can become quite involved and may contain a large number of parameters. Rate laws and enzyme parameters are still unknown for most enzymes. Results We introduce a simple and general rate law called "convenience kinetics". It can be derived from a simple random-order enzyme mechanism. Thermodynamic laws can impose dependencies on the kinetic parameters. Hence, to facilitate model fitting and parameter optimisation for large networks, we introduce thermodynamically independent system parameters: their values can be varied independently, without violating thermodynamical constraints. We achieve this by expressing the equilibrium constants either by Gibbs free energies of formation or by a set of independent equilibrium constants. The remaining system parameters are mean turnover rates, generalised Michaelis-Menten constants, and constants for inhibition and activation. All parameters correspond to molecular energies, for instance, binding energies between reactants and enzyme. Conclusion Convenience kinetics can be used to translate a biochemical network – manually or automatically - into a dynamical model with plausible biological properties. It implements enzyme saturation and regulation by activators and inhibitors, covers all possible reaction stoichiometries, and can be specified by a small number of parameters. Its mathematical form makes it especially suitable for parameter estimation and optimisation. Parameter estimates can be easily computed from a least-squares fit to Michaelis-Menten values, turnover rates, equilibrium constants, and other quantities that are routinely measured in enzyme assays and stored in kinetic databases.

  15. Supervised learning in a recurrent network of rate-model neurons exhibiting frequency adaptation.

    Science.gov (United States)

    Fortier, Pierre A; Guigon, Emmanuel; Burnod, Yves

    2005-09-01

    For gradient descent learning to yield connectivity consistent with real biological networks, the simulated neurons would have to include more realistic intrinsic properties such as frequency adaptation. However, gradient descent learning cannot be used straightforwardly with adapting rate-model neurons because the derivative of the activation function depends on the activation history. The objectives of this study were to (1) develop a simple computational approach to reproduce mathematical gradient descent and (2) use this computational approach to provide supervised learning in a network formed of rate-model neurons that exhibit frequency adaptation. The results of mathematical gradient descent were used as a reference in evaluating the performance of the computational approach. For this comparison, standard (nonadapting) rate-model neurons were used for both approaches. The only difference was the gradient calculation: the mathematical approach used the derivative at a point in weight space, while the computational approach used the slope for a step change in weight space. Theoretically, the results of the computational approach should match those of the mathematical approach, as the step size is reduced but floating-point accuracy formed a lower limit to usable step sizes. A systematic search for an optimal step size yielded a computational approach that faithfully reproduced the results of mathematical gradient descent. The computational approach was then used for supervised learning of both connection weights and intrinsic properties of rate-model neurons to convert a tonic input into a phasic-tonic output pattern. Learning produced biologically realistic connectivity that essentially used a monosynaptic connection from the tonic input neuron to an output neuron with strong frequency adaptation as compared to a complex network when using nonadapting neurons. Thus, more biologically realistic connectivity was achieved by implementing rate-model neurons with

  16. Cortical Network Models of Firing Rates in the Resting and Active States Predict BOLD Responses.

    Directory of Open Access Journals (Sweden)

    Maxwell R Bennett

    Full Text Available Measurements of blood oxygenation level dependent (BOLD signals have produced some surprising observations. One is that their amplitude is proportional to the entire activity in a region of interest and not just the fluctuations in this activity. Another is that during sleep and anesthesia the average BOLD correlations between regions of interest decline as the activity declines. Mechanistic explanations of these phenomena are described here using a cortical network model consisting of modules with excitatory and inhibitory neurons, taken as regions of cortical interest, each receiving excitatory inputs from outside the network, taken as subcortical driving inputs in addition to extrinsic (intermodular connections, such as provided by associational fibers. The model shows that the standard deviation of the firing rate is proportional to the mean frequency of the firing when the extrinsic connections are decreased, so that the mean BOLD signal is proportional to both as is observed experimentally. The model also shows that if these extrinsic connections are decreased or the frequency of firing reaching the network from the subcortical driving inputs is decreased, or both decline, there is a decrease in the mean firing rate in the modules accompanied by decreases in the mean BOLD correlations between the modules, consistent with the observed changes during NREM sleep and under anesthesia. Finally, the model explains why a transient increase in the BOLD signal in a cortical area, due to a transient subcortical input, gives rises to responses throughout the cortex as observed, with these responses mediated by the extrinsic (intermodular connections.

  17. Determination of the light-induced degradation rate of the solar cell sensitizer N719 on TiO2 nanocrystalline particles

    DEFF Research Database (Denmark)

    Nour-Mohammadi, Farahnaz; Doan Nguyen, Sau; Boschloo, Gerrit

    2005-01-01

    The oxidative degradation rate, kdeg of the solar cell dye (Bu4N+)2 [Ru(dcbpyH)2(NCS)2]2–, referred to as N719 or [RuL2(NCS)2], was obtained by applying a simple model system. Colloidal solutions of N719-dyed TiO2 particles in acetonitrile were irradiated with 532-nm monochromatic light....... The stability of N719 dye during solar cell operation was discussed based on this number, and on values of the electron transfer rate between [Ru(III) L2(NCS) 2] and iodide that are available in the literature....

  18. Triboelectric Nanogenerator Enabled Body Sensor Network for Self-Powered Human Heart-Rate Monitoring.

    Science.gov (United States)

    Lin, Zhiming; Chen, Jun; Li, Xiaoshi; Zhou, Zhihao; Meng, Keyu; Wei, Wei; Yang, Jin; Wang, Zhong Lin

    2017-09-26

    Heart-rate monitoring plays a critical role in personal healthcare management. A low-cost, noninvasive, and user-friendly heart-rate monitoring system is highly desirable. Here, a self-powered wireless body sensor network (BSN) system is developed for heart-rate monitoring via integration of a downy-structure-based triboelectric nanogenerator (D-TENG), a power management circuit, a heart-rate sensor, a signal processing unit, and Bluetooth module for wireless data transmission. By converting the inertia energy of human walking into electric power, a maximum power of 2.28 mW with total conversion efficiency of 57.9% was delivered at low operation frequency, which is capable of immediately and sustainably driving the highly integrated BSN system. The acquired heart-rate signal by the sensor would be processed in the signal process circuit, sent to an external device via the Bluetooth module, and displayed on a personal cell phone in a real-time manner. Moreover, by combining a TENG-based generator and a TENG-based sensor, an all-TENG-based wireless BSN system was developed, realizing continuous and self-powered heart-rate monitoring. This work presents a potential method for personal heart-rate monitoring, featured as being self-powered, cost-effective, noninvasive, and user-friendly.

  19. Depression and unemployment incidence rate evolution in Portugal, 1995–2013: General Practitioner Sentinel Network data

    Science.gov (United States)

    Rodrigues, Ana Paula; Sousa-Uva, Mafalda; Fonseca, Rita; Marques, Sara; Pina, Nuno; Matias-Dias, Carlos

    2017-01-01

    ABSTRACT OBJECTIVE Quantify, for both genders, the correlation between the depression incidence rate and the unemployment rate in Portugal between 1995 and 2013. METHODS An ecological study was developed to correlate the evolution of the depression incidence rates estimated by the General Practitioner Sentinel Network and the annual unemployment rates provided by the National Statistical Institute in official publications. RESULTS There was a positive correlation between the depression incidence rate and the unemployment rate in Portugal, which was significant only for males (R2 = 0.83, p = 0.04). For this gender, an increase of 37 new cases of depression per 100,000 inhabitants was estimated for each 1% increase in the unemployment rate between 1995 and 2013. CONCLUSIONS Although the study design does not allow the establishment of a causal association between unemployment and depression, the results suggest that the evolution of unemployment in Portugal may have had a significant impact on the level of mental health of the Portuguese, especially among men. PMID:29166442

  20. Congestion-Aware Routing and Fuzzy-based Rate Controller for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    M. Hatamian

    2016-04-01

    Full Text Available In this paper, congestion-aware routing and fuzzy-based rate controller for wireless sensor networks (WSNs is proposed. The proposed method tries to make a distinction between locally generated data and transit data by using a priority-based mechanism which provides a novel queueing model. Furthermore, a novel congestion-aware routing using greedy approach is proposed. The proposed congestion-aware routing tries to find more affordable routes. Moreover, a fuzzy rate controller is utilized for rate controlling which uses two criteria as its inputs, including congestion score and buffer occupancy. These two parameters are based on total packet input rate, packet forwarding rate at MAC layer, number of packets in the queue buffer, and total buffer size at each node. As soon as the congestion is detected, the notification signal is sent to offspring nodes. As a result, they are able to adjust their data transmission rate. Simulation results clearly show that the implementation of the proposed method using a greedy approach and fuzzy logic has done significant reduction in terms of packet loss rate, end-to-end delay and average energy consumption.

  1. Effect and Analysis of Sustainable Cell Rate using MPEG video Traffic in ATM Networks

    Directory of Open Access Journals (Sweden)

    Sakshi Kaushal

    2006-04-01

    Full Text Available The broadband networks inhibit the capability to carry multiple types of traffic – voice, video and data, but these services need to be controlled according to the traffic contract negotiated at the time of the connection to maintain desired Quality of service. Such control techniques use traffic descriptors to evaluate its performance and effectiveness. In case of Variable Bit Rate (VBR services, Peak Cell Rate (PCR and its Cell Delay Variation Tolerance (CDVTPCR are mandatory descriptors. In addition to these, ATM Forum proposed Sustainable Cell Rate (SCR and its Cell delay variation tolerance (CDVTSCR. In this paper, we evaluated the impact of specific SCR and CDVTSCR values on the Usage Parameter Control (UPC performance in case of measured MPEG traffic for improving the efficiency

  2. Effect of Volatile Fatty Acid Concentration on Anaerobic Degradation Rate from Field Anaerobic Digestion Facilities Treating Food Waste Leachate in South Korea

    Directory of Open Access Journals (Sweden)

    Dong-Jin Lee

    2015-01-01

    Full Text Available The purpose of this study was to investigate the effect of volatile fatty acid concentration on anaerobic degradation rate of food waste leachate in the anaerobic digestion facilities. The anaerobic digestion facilities treating food waste leachate (FWL, codigestion with food leachate and animal manure (A-MIX, and codigestion with food waste leachate and sewage sludge (S-MIX were selected for this study. In accordance with the regulation under Wastes Control Act in South Korea, the guideline of volatile solid removal rate for anaerobic digestion facility is set as 65% for anaerobic degradation efficiency. Highest volatile solids removal rates were achieved from FWL (63.5% than A-MIX (56.4% and S-MIX (41.2%. Four out of eight FWLs met the guidelines. The concentration of volatile fatty acids, therefore, was analyzed to determine the relationship with volatile solid removal rate. The results showed that, in order to meet the Korean guideline of 65% volatile solid removal rate, volatile fatty acid concentrations should remain below 4,000 mg/L on the field anaerobic digestion facilities treating FWL. Volatile fatty acid concentrations should be used along with others as an operational parameter to control and manage the anaerobic digestion process.

  3. The effects of dynamical synapses on firing rate activity: a spiking neural network model.

    Science.gov (United States)

    Khalil, Radwa; Moftah, Marie Z; Moustafa, Ahmed A

    2017-11-01

    Accumulating evidence relates the fine-tuning of synaptic maturation and regulation of neural network activity to several key factors, including GABA A signaling and a lateral spread length between neighboring neurons (i.e., local connectivity). Furthermore, a number of studies consider short-term synaptic plasticity (STP) as an essential element in the instant modification of synaptic efficacy in the neuronal network and in modulating responses to sustained ranges of external Poisson input frequency (IF). Nevertheless, evaluating the firing activity in response to the dynamical interaction between STP (triggered by ranges of IF) and these key parameters in vitro remains elusive. Therefore, we designed a spiking neural network (SNN) model in which we incorporated the following parameters: local density of arbor essences and a lateral spread length between neighboring neurons. We also created several network scenarios based on these key parameters. Then, we implemented two classes of STP: (1) short-term synaptic depression (STD) and (2) short-term synaptic facilitation (STF). Each class has two differential forms based on the parametric value of its synaptic time constant (either for depressing or facilitating synapses). Lastly, we compared the neural firing responses before and after the treatment with STP. We found that dynamical synapses (STP) have a critical differential role on evaluating and modulating the firing rate activity in each network scenario. Moreover, we investigated the impact of changing the balance between excitation (E) and inhibition (I) on stabilizing this firing activity. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  4. Solar photocatalytic degradation of mono azo methyl orange and diazo reactive green 19 in single and binary dye solutions: adsorbability vs photodegradation rate.

    Science.gov (United States)

    Ong, Soon-An; Min, Ohm-Mar; Ho, Li-Ngee; Wong, Yee-Shian

    2013-05-01

    The objective of this study was to examine the effects of adsorbability and number of sulfonate group on solar photocatalytic degradation of mono azo methyl orange (MO) and diazo Reactive Green 19 (RG19) in single and binary dye solutions. The adsorption capacity of MO and RG19 onto the TiO₂ was 16.9 and 26.8 mg/g, respectively, in single dye solution, and reduced to 5.0 and 23.1 mg/g, respectively, in the binary dye solution. The data obtained for photocatalytic degradation of MO and RG19 in single and binary dye solution were well fitted with the Langmuir-Hinshelwood kinetic model. The pseudo-first-order rate constants of diazo RG19 were significant higher than the mono azo MO either in single or binary dye solutions. The higher number of sulfonate group in RG19 contributed to better adsorption capacity onto the surface of TiO₂ than MO indicating greater photocatalytic degradation rate.

  5. Protein quantity on the air-solid interface determines degradation rates of human growth hormone in lyophilized samples.

    Science.gov (United States)

    Xu, Yemin; Grobelny, Pawel; Von Allmen, Alexander; Knudson, Korben; Pikal, Michael; Carpenter, John F; Randolph, Theodore W

    2014-05-01

    Recombinant human growth hormone (rhGH) was lyophilized with various glass-forming stabilizers, employing cycles that incorporated various freezing and annealing procedures to manipulate glass formation kinetics, associated relaxation processes, and glass-specific surface areas (SSAs). The secondary structure in the cake was monitored by infrared and in reconstituted samples by circular dichroism. The rhGH concentrations on the surface of lyophilized powders were determined from electron spectroscopy for chemical analysis. Glass transition temperature (Tg ), SSAs, and water contents were determined immediately after lyophilization. Lyophilized samples were incubated at 323 K for 16 weeks, and the resulting extents of rhGH aggregation, oxidation, and deamidation were determined after rehydration. Water contents and Tg were independent of lyophilization process parameters. Compared with samples lyophilized after rapid freezing, rhGH in samples that had been annealed in frozen solids prior to drying, or annealed in glassy solids after secondary drying retained more native-like protein secondary structure, had a smaller fraction of the protein on the surface of the cake, and exhibited lower levels of degradation during incubation. A simple kinetic model suggested that the differences in the extent of rhGH degradation during storage in the dried state between different formulations and processing methods could largely be ascribed to the associated levels of rhGH at the solid-air interface after lyophilization. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  6. Protein Quantity on the Air-Solid Interface Determines Degradation Rates of Human Growth Hormone in Lyophilized Samples

    Science.gov (United States)

    Xu, Yemin; Grobelny, Pawel; von Allmen, Alexander; Knudson, Korben; Pikal, Michael; Carpenter, John F.; Randolph, Theodore W.

    2014-01-01

    rhGH was lyophilized with various glass-forming stabilizers, employing cycles that incorporated various freezing and annealing procedures to manipulate glass formation kinetics, associated relaxation processes and glass specific surface areas (SSA’s). The secondary structure in the cake was monitored by IR and in reconstituted samples by CD. The rhGH concentrations on the surface of lyophilized powders were determined from ESCA. Tg, SSA’s and water contents were determined immediately after lyophilization. Lyophilized samples were incubated at 323 K for 16 weeks, and the resulting extents of rhGH aggregation, oxidation and deamidation were determined after rehydration. Water contents and Tg were independent of lyophilization process parameters. Compared to samples lyophilized after rapid freezing, rhGH in samples that had been annealed in frozen solids prior to drying, or annealed in glassy solids after secondary drying retained more native-like protein secondary structure, had a smaller fraction of the protein on the surface of the cake and exhibited lower levels of degradation during incubation. A simple kinetic model suggested that the differences in the extent of rhGH degradation during storage in the dried state between different formulations and processing methods could largely be ascribed to the associated levels of rhGH at the solid-air interface after lyophilization. PMID:24623139

  7. A Comparative Study of Neural Networks and ANFIS for Forecasting Attendance Rate of Soccer Games

    Directory of Open Access Journals (Sweden)

    Mehmet Şahin

    2017-11-01

    Full Text Available The main purpose of this study was to develop and apply a neural network (NN approach and an adaptive neuro-fuzzy inference system (ANFIS model for forecasting the attendance rates at soccer games. The models were designed based on the characteristics of the problem. Past real data was used. Training data was used for training the models, and the testing data was used for evaluating the performance of the forecasting models. The obtained forecasting results were compared to the actual data and to each other. To evaluate the performance of the models, two statistical indicators, Mean Absolute Deviation (MAD and mean absolute percent error (MAPE, were used. Based on the results, the proposed neural network approach and the ANFIS model were shown to be effective in forecasting attendance at soccer games. The neural network approach performed better than the ANFIS model. The main contribution of this study is to introduce two effective techniques for estimating attendance at sports games. This is the first attempt to use an ANFIS model for that purpose.

  8. Joint sensor placement and power rating selection in energy harvesting wireless sensor networks

    KAUST Repository

    Bushnaq, Osama M.

    2017-11-02

    In this paper, the focus is on optimal sensor placement and power rating selection for parameter estimation in wireless sensor networks (WSNs). We take into account the amount of energy harvested by the sensing nodes, communication link quality, and the observation accuracy at the sensor level. In particular, the aim is to reconstruct the estimation parameter with minimum error at a fusion center under a system budget constraint. To achieve this goal, a subset of sensing locations is selected from a large pool of candidate sensing locations. Furthermore, the type of sensor to be placed at those locations is selected from a given set of sensor types (e.g., sensors with different power ratings). We further investigate whether it is better to install a large number of cheap sensors, a few expensive sensors or a combination of different sensor types at the optimal locations.

  9. Informatics technology mimics ecology: dense, mutualistic collaboration networks are associated with higher publication rates.

    Directory of Open Access Journals (Sweden)

    Marco D Sorani

    Full Text Available Information technology (IT adoption enables biomedical research. Publications are an accepted measure of research output, and network models can describe the collaborative nature of publication. In particular, ecological networks can serve as analogies for publication and technology adoption. We constructed network models of adoption of bioinformatics programming languages and health IT (HIT from the literature.We selected seven programming languages and four types of HIT. We performed PubMed searches to identify publications since 2001. We calculated summary statistics and analyzed spatiotemporal relationships. Then, we assessed ecological models of specialization, cooperativity, competition, evolution, biodiversity, and stability associated with publications.Adoption of HIT has been variable, while scripting languages have experienced rapid adoption. Hospital systems had the largest HIT research corpus, while Perl had the largest language corpus. Scripting languages represented the largest connected network components. The relationship between edges and nodes was linear, though Bioconductor had more edges than expected and Perl had fewer. Spatiotemporal relationships were weak. Most languages shared a bioinformatics specialization and appeared mutualistic or competitive. HIT specializations varied. Specialization was highest for Bioconductor and radiology systems. Specialization and cooperativity were positively correlated among languages but negatively correlated among HIT. Rates of language evolution were similar. Biodiversity among languages grew in the first half of the decade and stabilized, while diversity among HIT was variable but flat. Compared with publications in 2001, correlation with publications one year later was positive while correlation after ten years was weak and negative.Adoption of new technologies can be unpredictable. Spatiotemporal relationships facilitate adoption but are not sufficient. As with ecosystems, dense

  10. Extraction of elementary rate constants from global network analysis of E. coli central metabolism

    Directory of Open Access Journals (Sweden)

    Broderick Gordon

    2008-05-01

    Full Text Available Abstract Background As computational performance steadily increases, so does interest in extending one-particle-per-molecule models to larger physiological problems. Such models however require elementary rate constants to calculate time-dependent rate coefficients under physiological conditions. Unfortunately, even when in vivo kinetic data is available, it is often in the form of aggregated rate laws (ARL that do not specify the required elementary rate constants corresponding to mass-action rate laws (MRL. There is therefore a need to develop a method which is capable of automatically transforming ARL kinetic information into more detailed MRL rate constants. Results By incorporating proteomic data related to enzyme abundance into an MRL modelling framework, here we present an efficient method operating at a global network level for extracting elementary rate constants from experiment-based aggregated rate law (ARL models. The method combines two techniques that can be used to overcome the difficult properties in parameterization. The first, a hybrid MRL/ARL modelling technique, is used to divide the parameter estimation problem into sub-problems, so that the parameters of the mass action rate laws for each enzyme are estimated in separate steps. This reduces the number of parameters that have to be optimized simultaneously. The second, a hybrid algebraic-numerical simulation and optimization approach, is used to render some rate constants identifiable, as well as to greatly narrow the bounds of the other rate constants that remain unidentifiable. This is done by incorporating equality constraints derived from the King-Altman and Cleland method into the simulated annealing algorithm. We apply these two techniques to estimate the rate constants of a model of E. coli glycolytic pathways. The simulation and statistical results show that our innovative method performs well in dealing with the issues of high computation cost, stiffness, local

  11. Research on Mixed Data Rate and Format Transmission in WDM Networks

    Directory of Open Access Journals (Sweden)

    LI Hong-an

    2013-03-01

    Full Text Available To meet the growing data traffic demands in the telecommunication applications, the number of wavelengths is to be increased in a fiber-optic backbone of the telecommunication network. The exponential growth of internet services, transmission capacity is a tremendous challenge to networks.   Nowadays, 10 Gb/s transmission systems are being used for commercial applications.  At the same time, the non-linear effects such as FWM, SRS, XPM, SPM, and Dispersion are also increased, when the number of wavelengths passing through the single fiber is increased. The analysis of efficient modulation formats for   DWDM system and    long-haul transmission system, we go for various modulations for DWDM system. The maimum data rate for NRZ-OOK modulation format is 10 Gb/s. For RZ-OOK the maximum rate is 50 Gb/s.  Since RZ-OOK modulation uses twice the band width when compared to NRZ-OOK modulation. The modulation format is partially upgraded from OOK to PSK, the influence of OOK signals on the updated PSK signals must be considered when using multi-channel wavelength conversion. The PSK modulation is also analyzed.

  12. Neural Network for Determining Risk Rate of Post-Heart Stroke Patients

    Directory of Open Access Journals (Sweden)

    Oldřich Trenz

    2014-01-01

    Full Text Available The ischemic heart disease presents an important health problem that affects a great part of the population and is the cause of one third of all deaths in the Czech Republic. The availability of data describing the patients’ prognosis enables their further analysis, with the aim of lowering the patients’ risk, by proposing optimum treatment. The main reason for creating the neural network model is not only to automate the process of establishing the risk rate of patients suffering from ischemic heart disease, but also to adapt it for practical use in clinical conditions. Our aim is to identify especially the specific group of risk-rate patients whose well-timed preventive care can improve the quality and prolong the length of their lives.The aim of the paper is to propose a patient-parameter structure, using which we could create a suitable model based on a self-taught neural network. The emphasis is placed on identifying key descriptive parameters (in the form of a reduction of the available descriptive parameters that are crucial for identifying the required patients, and simultaneously to achieve a portability of the model among individual clinical workplaces (availability of parameters.

  13. Prediction of road traffic death rate using neural networks optimised by genetic algorithm.

    Science.gov (United States)

    Jafari, Seyed Ali; Jahandideh, Sepideh; Jahandideh, Mina; Asadabadi, Ebrahim Barzegari

    2015-01-01

    Road traffic injuries (RTIs) are realised as a main cause of public health problems at global, regional and national levels. Therefore, prediction of road traffic death rate will be helpful in its management. Based on this fact, we used an artificial neural network model optimised through Genetic algorithm to predict mortality. In this study, a five-fold cross-validation procedure on a data set containing total of 178 countries was used to verify the performance of models. The best-fit model was selected according to the root mean square errors (RMSE). Genetic algorithm, as a powerful model which has not been introduced in prediction of mortality to this extent in previous studies, showed high performance. The lowest RMSE obtained was 0.0808. Such satisfactory results could be attributed to the use of Genetic algorithm as a powerful optimiser which selects the best input feature set to be fed into the neural networks. Seven factors have been known as the most effective factors on the road traffic mortality rate by high accuracy. The gained results displayed that our model is very promising and may play a useful role in developing a better method for assessing the influence of road traffic mortality risk factors.

  14. Methodology for earthquake rupture rate estimates of fault networks: example for the western Corinth rift, Greece

    Science.gov (United States)

    Chartier, Thomas; Scotti, Oona; Lyon-Caen, Hélène; Boiselet, Aurélien

    2017-10-01

    Modeling the seismic potential of active faults is a fundamental step of probabilistic seismic hazard assessment (PSHA). An accurate estimation of the rate of earthquakes on the faults is necessary in order to obtain the probability of exceedance of a given ground motion. Most PSHA studies consider faults as independent structures and neglect the possibility of multiple faults or fault segments rupturing simultaneously (fault-to-fault, FtF, ruptures). The Uniform California Earthquake Rupture Forecast version 3 (UCERF-3) model takes into account this possibility by considering a system-level approach rather than an individual-fault-level approach using the geological, seismological and geodetical information to invert the earthquake rates. In many places of the world seismological and geodetical information along fault networks is often not well constrained. There is therefore a need to propose a methodology relying on geological information alone to compute earthquake rates of the faults in the network. In the proposed methodology, a simple distance criteria is used to define FtF ruptures and consider single faults or FtF ruptures as an aleatory uncertainty, similarly to UCERF-3. Rates of earthquakes on faults are then computed following two constraints: the magnitude frequency distribution (MFD) of earthquakes in the fault system as a whole must follow an a priori chosen shape and the rate of earthquakes on each fault is determined by the specific slip rate of each segment depending on the possible FtF ruptures. The modeled earthquake rates are then compared to the available independent data (geodetical, seismological and paleoseismological data) in order to weight different hypothesis explored in a logic tree.The methodology is tested on the western Corinth rift (WCR), Greece, where recent advancements have been made in the understanding of the geological slip rates of the complex network of normal faults which are accommodating the ˜ 15 mm yr-1 north

  15. A Decade of Improvements for Solid Oxide Electrolysis Cells. Long-Term Degradation Rate from 40%/Kh to 0.4 % Kh

    DEFF Research Database (Denmark)

    Hauch, Anne; Brodersen, Karen; Chen, Ming

    2016-01-01

    are to provide inexpensive, reliable, high performing and long-term stable SOEC for stack and system applications. At DTU Energy (formerly Department of Fuel Cells and Solid State Chemistry, Risø National Laboratory), research within SOEC for more than a decade has led to long-term degradation rates on cell...... level being improved from 40 %/kh to 0.4 %/kh for tests at -1 A/cm2 (figure 1). In this paper, we review the key findings and highlight different performance and durability limiting factors that have been discovered, analyzed and addressed over the years to reach the tremendous increase in long...

  16. Flexible-rate optical packet generation/detection and label swapping for optical label switching networks

    Science.gov (United States)

    Wu, Zhongying; Li, Juhao; Tian, Yu; Ge, Dawei; Zhu, Paikun; Chen, Yuanxiang; Chen, Zhangyuan; He, Yongqi

    2017-03-01

    In recent years, optical label switching (OLS) gains lots of attentions due to its intrinsic advantages to implement protocol, bit-rate, granularity and data format transparency packet switching. In this paper, we propose a novel scheme to realize flexible-rate optical packet switching for OLS networks. At the transmitter node, flexible-rate packet is generated by parallel modulating different combinations of optical carriers generated from the optical multi-carrier generator (OMCG), among which the low-speed optical label occupies one carrier. At the switching node, label is extracted and re-generated in label processing unit (LPU). The payloads are switched based on routing information and new label is added after switching. At the receiver node, another OMCG serves as local oscillators (LOs) for optical payloads coherent detection. The proposed scheme offers good flexibility for dynamic optical packet switching by adjusting the payload bandwidth and could also effectively reduce the number of lasers, modulators and receivers for packet generation/detection. We present proof-of-concept demonstrations of flexible-rate packet generation/detection and label swapping in 12.5 GHz grid. The influence of crosstalk for cascaded label swapping is also investigated.

  17. Implementation of a wireless sensor network for heart rate monitoring in a senior center.

    Science.gov (United States)

    Huang, Jyh-How; Su, Tzu-Yao; Raknim, Paweeya; Lan, Kun-Chan

    2015-06-01

    Wearable sensor systems are widely used to monitor vital sign in hospitals and in recent years have also been used at home. In this article we present a system that includes a ring probe, sensor, radio, and receiver, designed for use as a long-term heart rate monitoring system in a senior center. The primary contribution of this article is successfully implementing a cheap, large-scale wireless heart rate monitoring system that is stable and comfortable to use 24 h a day. We developed new finger ring sensors for comfortable continuous wearing experience and used dynamic power adjustment on the ring so the sensor can detect pulses at different strength levels. Our system has been deployed in a senior center since May 2012, and 63 seniors have used this system in this period. During the 54-h system observation period, 10 alarms were set off. Eight of them were due to abnormal heart rate, and two of them were due to loose probes. The monitoring system runs stably with the senior center's existing WiFi network, and achieves 99.48% system availability. The managers and caregivers use our system as a reliable warning system for clinical deterioration. The results of the year-long deployment show that the wireless group heart rate monitoring system developed in this work is viable for use within a designated area.

  18. Effects of network dissolution changes on pore-to-core upscaled reaction rates for kaolinite and anorthite reactions under acidic conditions

    KAUST Repository

    Kim, Daesang

    2013-11-01

    We have extended reactive flow simulation in pore-network models to include geometric changes in the medium from dissolution effects. These effects include changes in pore volume and reactive surface area, as well as topological changes that open new connections. The computed changes were based upon a mineral map from an X-ray computed tomography image of a sandstone core. We studied the effect of these changes on upscaled (pore-scale to core-scale) reaction rates and compared against the predictions of a continuum model. Specifically, we modeled anorthite and kaolinite reactions under acidic flow conditions during which the anorthite reactions remain far from equilibrium (dissolution only), while the kaolinite reactions can be near-equilibrium. Under dissolution changes, core-scale reaction rates continuously and nonlinearly evolved in time. At higher injection rates, agreement with predictions of the continuum model degraded significantly. For the far-from-equilibrium reaction, our results indicate that the ability to correctly capture the heterogeneity in dissolution changes in the reactive mineral surface area is critical to accurately predict upscaled reaction rates. For the near-equilibrium reaction, the ability to correctly capture the heterogeneity in the saturation state remains critical. Inclusion of a Nernst-Planck term to ensure neutral ionic currents under differential diffusion resulted in at most a 9% correction in upscaled rates.

  19. Estimation of Leak Flow Rate during Post-LOCA Using Cascaded Fuzzy Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Yeong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Na, Man Gyun [Chosun University, Gwangju (Korea, Republic of)

    2016-10-15

    In this study, important parameters such as the break position, size, and leak flow rate of loss of coolant accidents (LOCAs), provide operators with essential information for recovering the cooling capability of the nuclear reactor core, for preventing the reactor core from melting down, and for managing severe accidents effectively. Leak flow rate should consist of break size, differential pressure, temperature, and so on (where differential pressure means difference between internal and external reactor vessel pressure). The leak flow rate is strongly dependent on the break size and the differential pressure, but the break size is not measured and the integrity of pressure sensors is not assured in severe circumstances. In this paper, a cascaded fuzzy neural network (CFNN) model is appropriately proposed to estimate the leak flow rate out of break, which has a direct impact on the important times (time approaching the core exit temperature that exceeds 1200 .deg. F, core uncover time, reactor vessel failure time, etc.). The CFNN is a data-based model, it requires data to develop and verify itself. Because few actual severe accident data exist, it is essential to obtain the data required in the proposed model using numerical simulations. In this study, a CFNN model was developed to predict the leak flow rate before proceeding to severe LOCAs. The simulations showed that the developed CFNN model accurately predicted the leak flow rate with less error than 0.5%. The CFNN model is much better than FNN model under the same conditions, such as the same fuzzy rules. At the result of comparison, the RMS errors of the CFNN model were reduced by approximately 82 ~ 97% of those of the FNN model.

  20. Blocking probabilities in mobile communications networks with time-varying rates ad redialing subscribers

    NARCIS (Netherlands)

    Abdalla, Nadra; Boucherie, Richardus J.

    Call-blocking probabilities are among the key performance measures in mobile communications networks. For their analysis, mobile networks can be modelled as networks of Erlang loss queues with common capacity restrictions dictated by the allocation of frequencies to the cells of the network.

  1. Resource allocation via sum-rate maximization in the uplink of multi-cell OFDMA networks

    KAUST Repository

    Tabassum, Hina

    2012-10-03

    In this paper, we consider maximizing the sum rate in the uplink of a multi-cell orthogonal frequency-division multiple access network. The problem has a non-convex combinatorial structure and is known to be NP-hard. Because of the inherent complexity of implementing the optimal solution, firstly, we derive an upper bound (UB) and a lower bound (LB) to the optimal average network throughput. Moreover, we investigate the performance of a near-optimal single cell resource allocation scheme in the presence of inter-cell interference, which leads to another easily computable LB. We then develop a centralized sub-optimal scheme that is composed of a geometric programming-based power control phase in conjunction with an iterative subcarrier allocation phase. Although the scheme is computationally complex, it provides an effective benchmark for low complexity schemes even without the power control phase. Finally, we propose less complex centralized and distributed schemes that are well suited for practical scenarios. The computational complexity of all schemes is analyzed, and the performance is compared through simulations. Simulation results demonstrate that the proposed low complexity schemes can achieve comparable performance with that of the centralized sub-optimal scheme in various scenarios. Moreover, comparisons with the UB and LB provide insight on the performance gap between the proposed schemes and the optimal solution. Copyright © 2011 John Wiley & Sons, Ltd.

  2. An Efficient Biometric-Based Algorithm Using Heart Rate Variability for Securing Body Sensor Networks

    Directory of Open Access Journals (Sweden)

    Sandeep Pirbhulal

    2015-06-01

    Full Text Available Body Sensor Network (BSN is a network of several associated sensor nodes on, inside or around the human body to monitor vital signals, such as, Electroencephalogram (EEG, Photoplethysmography (PPG, Electrocardiogram (ECG, etc. Each sensor node in BSN delivers major information; therefore, it is very significant to provide data confidentiality and security. All existing approaches to secure BSN are based on complex cryptographic key generation procedures, which not only demands high resource utilization and computation time, but also consumes large amount of energy, power and memory during data transmission. However, it is indispensable to put forward energy efficient and computationally less complex authentication technique for BSN. In this paper, a novel biometric-based algorithm is proposed, which utilizes Heart Rate Variability (HRV for simple key generation process to secure BSN. Our proposed algorithm is compared with three data authentication techniques, namely Physiological Signal based Key Agreement (PSKA, Data Encryption Standard (DES and Rivest Shamir Adleman (RSA. Simulation is performed in Matlab and results suggest that proposed algorithm is quite efficient in terms of transmission time utilization, average remaining energy and total power consumption.

  3. Combined D-optimal design and generalized regression neural network for modeling of plasma etching rate

    Directory of Open Access Journals (Sweden)

    You Hailong

    2014-01-01

    Full Text Available Plasma etching process plays a critical role in semiconductor manufacturing. Because physical and chemical mechanisms involved in plasma etching are extremely complicated, models supporting process control are difficult to construct. This paper uses a 35-run D-optimal design to efficiently collect data under well planned conditions for important controllable variables such as power, pressure, electrode gap and gas flows of Cl2 and He and the response, etching rate, for building an empirical underlying model. Since the relationship between the control and response variables could be highly nonlinear, a generalized regression neural network is used to select important model variables and their combination effects and to fit the model. Compared with the response surface methodology, the proposed method has better prediction performance in training and testing samples. A success application of the model to control the plasma etching process demonstrates the effectiveness of the methods.

  4. Maximum entropy modeling of metabolic networks by constraining growth-rate moments predicts coexistence of phenotypes

    Science.gov (United States)

    De Martino, Daniele

    2017-12-01

    In this work maximum entropy distributions in the space of steady states of metabolic networks are considered upon constraining the first and second moments of the growth rate. Coexistence of fast and slow phenotypes, with bimodal flux distributions, emerges upon considering control on the average growth (optimization) and its fluctuations (heterogeneity). This is applied to the carbon catabolic core of Escherichia coli where it quantifies the metabolic activity of slow growing phenotypes and it provides a quantitative map with metabolic fluxes, opening the possibility to detect coexistence from flux data. A preliminary analysis on data for E. coli cultures in standard conditions shows degeneracy for the inferred parameters that extend in the coexistence region.

  5. Cooperative Spatial Reuse with Transmit Beamforming in Multi-rate Wireless Networks

    DEFF Research Database (Denmark)

    Lu, Chenguang; Fitzek, Frank; Eggers, Patrick Claus F.

    2009-01-01

    We present a cooperative spatial reuse (CSR) scheme as a cooperative extension of the current TDMA-based MAC to enable spatial reuse in multi-rate wireless networks. We model spatial reuse as a cooperation problem on utilizing the time slots obtained from the TDMA-based MAC. In CSR, there are two...... will leave spatial reuse mode and switch back to TDMA. In this work, we focus on the transmit beamforming techniques to enable CSR by interference cancellation on MISO (Multiple Input Single Output) links. We compare the CSR scheme using zero-forcing (ZF) transmit beamforming, namely ZF-CSR, to the TDMA......-based MAC using maximum ratio combining (MRC) transmit beamforming, namely MRC-TDMA. The numerical results of a simulated two 2 × 1 MISO links scenario show the great potential of CSR to substantially increase the capacity and energy efficiency. Udgivelsesdato: Feb. 2009...

  6. Spatial interpolation and radiological mapping of ambient gamma dose rate by using artificial neural networks and fuzzy logic methods.

    Science.gov (United States)

    Yeşilkanat, Cafer Mert; Kobya, Yaşar; Taşkın, Halim; Çevik, Uğur

    2017-09-01

    The aim of this study was to determine spatial risk dispersion of ambient gamma dose rate (AGDR) by using both artificial neural network (ANN) and fuzzy logic (FL) methods, compare the performances of methods, make dose estimations for intermediate stations with no previous measurements and create dose rate risk maps of the study area. In order to determine the dose distribution by using artificial neural networks, two main networks and five different network structures were used; feed forward ANN; Multi-layer perceptron (MLP), Radial basis functional neural network (RBFNN), Quantile regression neural network (QRNN) and recurrent ANN; Jordan networks (JN), Elman networks (EN). In the evaluation of estimation performance obtained for the test data, all models appear to give similar results. According to the cross-validation results obtained for explaining AGDR distribution, Pearson's r coefficients were calculated as 0.94, 0.91, 0.89, 0.91, 0.91 and 0.92 and RMSE values were calculated as 34.78, 43.28, 63.92, 44.86, 46.77 and 37.92 for MLP, RBFNN, QRNN, JN, EN and FL, respectively. In addition, spatial risk maps showing distributions of AGDR of the study area were created by all models and results were compared with geological, topological and soil structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Consistent dust and gas models for protoplanetary disks. II. Chemical networks and rates

    Science.gov (United States)

    Kamp, I.; Thi, W.-F.; Woitke, P.; Rab, C.; Bouma, S.; Ménard, F.

    2017-11-01

    Aims: We aim to define a small and large chemical network which can be used for the quantitative simultaneous analysis of molecular emission from the near-IR to the submm. We also aim to revise reactions of excited molecular hydrogen, which are not included in UMIST, to provide a homogeneous database for future applications. Methods: We have used the thermo-chemical disk modeling code ProDiMo and a standard T Tauri disk model to evaluate the impact of various chemical networks, reaction rate databases and sets of adsorption energies on a large sample of chemical species and emerging line fluxes from the near-IR to the submm wavelength range. Results: We find large differences in the masses and radial distribution of ice reservoirs when considering freeze-out on bare or polar ice coated grains. Most strongly the ammonia ice mass and the location of the snow line (water) change. As a consequence molecules associated to the ice lines such as N2H+ change their emitting region; none of the line fluxes in the sample considered here changes by more than 25% except CO isotopologues, CN and N2H+ lines. The three-body reaction N+H2+M plays a key role in the formation of water in the outer disk. Besides that, differences between the UMIST 2006 and 2012 database change line fluxes in the sample considered here by less than a factor of two (a subset of low excitation CO and fine structure lines stays even within 25%); exceptions are OH, CN, HCN, HCO+ and N2H+ lines. However, different networks such as OSU and KIDA 2011 lead to pronounced differences in the chemistry inside 100 au and thus affect emission lines from high excitation CO, OH and CN lines. H2 is easily excited at the disk surface and state-to-state reactions enhance the abundance of CH+ and to a lesser extent HCO+. For sub-mm lines of HCN, N2H+ and HCO+, a more complex larger network is recommended. Conclusions: More work is required to consolidate data on key reactions leading to the formation of water, molecular

  8. Determination of degradation rates of organic substances in the unsaturated soil zone depending on the grain size fractions of various soil types

    Science.gov (United States)

    Fichtner, Thomas; Stefan, Catalin; Goersmeyer, Nora

    2015-04-01

    Rate and extent of the biological degradation of organic substances during transport through the unsaturated soil zone is decisively influenced by the chemical and physical properties of the pollutants such as water solubility, toxicity and molecular structure. Furthermore microbial degradation processes are also influenced by soil-specific properties. An important parameter is the soil grain size distribution on which the pore volume and the pore size depends. Changes lead to changes in air and water circulation as well as preferred flow paths. Transport capacity of water inclusive nutrients is lower in existing bad-drainable fine pores in soils with small grain size fractions than in well-drainable coarse pores in a soil with bigger grain size fractions. Because fine pores are saturated with water for a longer time than the coarse pores and oxygen diffusion in water is ten thousand times slower than in air, oxygen is replenished much slower in soils with small grain size fractions. As a result life and growth conditions of the microorganisms are negatively affected. This leads to less biological activity, restricted degradation/mineralization of pollutants or altered microbial processes. The aim of conducted laboratory column experiments was to study the correlation between the grain size fractions respectively pore sizes, the oxygen content and the biodegradation rate of infiltrated organic substances. Therefore two columns (active + sterile control) were filled with different grain size fractions (0,063-0,125 mm, 0,2-0,63 mm and 1-2 mm) of soils. The sterile soil was inoculated with a defined amount of a special bacteria culture (sphingobium yanoikuae). A solution with organic substances glucose, oxalic acid, sinaphylic alcohol and nutrients was infiltrated from the top in intervals. The degradation of organic substances was controlled by the measurement of dissolved organic carbon in the in- and outflow of the column. The control of different pore volumes

  9. Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. II. In vitro and in vivo biological evaluation.

    Science.gov (United States)

    Fu, Qiang; Rahaman, Mohamed N; Bal, B Sonny; Bonewald, Lynda F; Kuroki, Keiichi; Brown, Roger F

    2010-10-01

    In Part I, the in vitro degradation of bioactivAR52115e glass scaffolds with a microstructure similar to that of human trabecular bone, but with three different compositions, was investigated as a function of immersion time in a simulated body fluid. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. This work is an extension of Part I, to investigate the effect of the glass composition on the in vitro response of osteogenic MLO-A5 cells to these scaffolds, and on the ability of the scaffolds to support tissue infiltration in a rat subcutaneous implantation model. The results of assays for cell viability and alkaline phosphatase activity showed that the slower degrading silicate 13-93 and borosilicate 13-93B1 scaffolds were far better than the borate 13-93B3 scaffolds in supporting cell proliferation and function. However, all three groups of scaffolds showed the ability to support tissue infiltration in vivo after implantation for 6 weeks. The results indicate that the required bioactivity and degradation rate may be achieved by substituting an appropriate amount of SiO2 in 13-93 glass with B2O3, and that these trabecular glass scaffolds could serve as substrates for the repair and regeneration of contained bone defects. Copyright 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

  10. Effect of sex, testosterone propionate and trienbolone acetate on the rate of growth and myofibrillar protein degradation in growing young rats.

    Science.gov (United States)

    Santidrian, S; Thompson, J R

    1982-01-01

    The urinary output of N tau-methylhistidine (3-methylhistidine: 3-Mehis) was determined to evaluate the effect of testosterone propionate (TP, 1 mg/100g body weight per day) and trienbolone acetate (3-oxo-17 beta-hydroxy-4,9,11-estratriene acetate, TBA 1 mg/100g body weight per day) on the rate of myofibrillar protein breakdown in young growing intact and adrenalectomized (AdX) male and female rats. Injections were given subcutaneously for 14 days. Body weight changes were recorded daily throughout the experiment. Compared with the intact control rats, male-AdX rats had a significant (p less than 0.05) reduction in both growth and 3-Mehis output (and, therefore, a reduction in the rate of myofibrillar protein degradation). Administration of the anabolic steroids to these rats had no significant effect on growth but increased the rate of 3-Mehis output to the normal range in the case of TP, and above the normal range (p less than 0.05) in the case of TBA. However, compared with the intact female rats, female-AdX rats showed a significant (p less than 0.05) increase in 3-Mehis output. Administration of either TP or TBA to these animals significantly (p less than 0.05) increased growth and reduced 3-Mehis output. The response of myofibrillar protein degradation in AdX rats to TP or TBA administration is strongly dependent on the sex of the animals. The anabolic action of TP and TBA, especially in female rats, may be mediated through an antagonistic effect to the catabolic effects of oestrogens and glucocorticoids.

  11. A poly(glycerol sebacate)-coated mesoporous bioactive glass scaffold with adjustable mechanical strength, degradation rate, controlled-release and cell behavior for bone tissue engineering.

    Science.gov (United States)

    Lin, Dan; Yang, Kai; Tang, Wei; Liu, Yutong; Yuan, Yuan; Liu, Changsheng

    2015-07-01

    Various requirements in the field of tissue engineering have motivated the development of three-dimensional scaffold with adjustable physicochemical properties and biological functions. A series of multiparameter-adjustable mesoporous bioactive glass (MBG) scaffolds with uncrosslinked poly(glycerol sebacate) (PGS) coating was prepared in this article. MBG scaffold was prepared by a modified F127/PU co-templating process and then PGS was coated by a simple adsorption and lyophilization process. Through controlling macropore parameters and PGS coating amount, the mechanical strength, degradation rate, controlled-release and cell behavior of the composite scaffold could be modulated in a wide range. PGS coating successfully endowed MBG scaffold with improved toughness and adjustable mechanical strength covering the bearing range of trabecular bone (2-12MPa). Multilevel degradation rate of the scaffold and controlled-release rate of protein from mesopore could be achieved, with little impact on the protein activity owing to an "ultralow-solvent" coating and "nano-cavity entrapment" immobilization method. In vitro studies indicated that PGS coating promoted cell attachment and proliferation in a dose-dependent manner, without affecting the osteogenic induction capacity of MBG substrate. These results first provide strong evidence that uncrosslinked PGS might also yield extraordinary achievements in traditional MBG scaffold. With the multiparameter adjustability, the composite MBG/PGS scaffolds would have a hopeful prospect in bone tissue engineering. The design considerations and coating method of this study can also be extended to other ceramic-based artificial scaffolds and are expected to provide new thoughts on development of future tissue engineering materials. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Status Report - Cane Fiberboard Properties And Degradation Rates For Storage Of The 9975 Shipping Package In KAC

    Energy Technology Data Exchange (ETDEWEB)

    Daugherty, W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-12-22

    Thermal, mechanical and physical properties have been measured on cane fiberboard samples following accelerated aging for up to approximately 10 years. The aging environments have included elevated temperature < 250 ºF (the maximum allowed service temperature for fiberboard in 9975 packages) and elevated humidity. The results from this testing have been analyzed, and aging models fit to the data. Correlations relating several properties (thermal conductivity, energy absorption, weight, dimensions and density) to their rate of change in potential storage environments have been developed. Combined with an estimate of the actual conditions the fiberboard experiences in KAC, these models allow development of service life predictions.

  13. Status Report - Softwood Fiberboard Properties And Degradation Rates For Storage Of The 9975 Shipping Package In KAC

    Energy Technology Data Exchange (ETDEWEB)

    Daugherty, W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-12-22

    Thermal, mechanical and physical properties have been measured on softwood fiberboard samples following accelerated aging for up to approximately 7 years. The aging environments have included elevated temperature < 250 ºF (the maximum allowed service temperature for fiberboard in 9975 packages) and elevated humidity. The results from this testing have been analyzed, and preliminary aging models fit to the data. Correlations relating several properties (thermal conductivity, energy absorption, weight, dimensions and density) to their rate of change in potential storage environments have been developed. Combined with acceptance criteria and an estimate of the actual conditions the fiberboard experiences in KAC, these models allow development of service life predictions.

  14. Linking charring temperature and wood source to the structure and degradation rates of pyrogenic organic matter in soil

    Science.gov (United States)

    Hatton, P.; Dastmalchi, K.; Chatterjee, S.; Auclerc, A.; Le Moine, J.; Filley, T. R.; Nadelhoffer, K. J.; Stark, R.; Bird, J. A.

    2013-12-01

    Fire is a major controller of forest C cycling by releasing CO2 to the atmosphere and by contributing pyrogenic organic matter (PyOM or biochar) to soils. Recent studies have shown that much of fire-derived PyOM may turn over in soils at century time scales. Two likely controllers of the chemical structure of PyOM and its resulting decay rate are pyrolysis temperature and the source biomass. However, we know little of how these two factors determine the chemical structure and bioreactivity of the resulting PyOM. To gain further insight into controls on the structure and fate of PyOM, we examined two species of dual-labeled (13C/15N), wood-based PyOM (Pinus banksiana and Acer rubrum) made with 5 pyrolysis temperatures (0, 200, 300, 450, 600 °C) using solid state nuclear magnetic resonance, isotopic and elemental composition (C, H, O, and N), and differential scanning calorimetry. In addition, we are investigating the fate of a subset of these PyOM materials applied to forest soils in a long-term field study located at the University of Michigan Biological Station in Pellston, MI, USA. We will present data of the loss of PyOM C as CO2 and DOC during the first year in situ. We found complementary lines of evidence for a facile removal of cellulose and hemicellulose and a progressive alteration of nitrogenous moieties across the charring gradient for wood-derived PyOM of both tree species as temperature was increased from 0 to 600 °C. Our NMR results show a significant species by pyrolysis temperature interaction on PyOM chemical structure with considerably less condensation for Acer- than Pinus-derived PyOM at 300 °C. In the first year after addition to soil, Acer-derived PyOM pyrolyzed at 450 °C mineralized faster than Pinus-derived PyOM pyrolyzed at 450 °C. Increasing pyrolysis temperatures for Pinus-derived PyOM also resulted in slower CO2 mineralization rates during the first year of field decay. These results relate pyrolysis temperature to the resulting Py

  15. Hydroxyl-radical-induced degradative oxidation of beta-lactam antibiotics in water: absolute rate constant measurements.

    Science.gov (United States)

    Dail, Michelle K; Mezyk, Stephen P

    2010-08-19

    The beta-lactam antibiotics are some of the most prevalent pharmaceutical contaminants currently being detected in aquatic environments. Because the presence of any trace level of antibiotic in water may adversely affect aquatic ecosystems and contribute to the production of antibiotic-resistant bacteria, active removal by additional water treatments, such as using advanced oxidation and reduction processes (AO/RPs), may be required. However, to ensure that any AOP treatment process occurs efficiently and quantitatively, a full understanding of the kinetics and mechanisms of all of the chemical reactions involved under the conditions of use is necessary. In this study, we report on our kinetic measurements for the hydroxyl-radical-induced oxidation of 11 beta-lactam antibiotics obtained using electron pulse radiolysis techniques. For the 5-member ring species, an average reaction rate constant of (7.9 +/- 0.8) x 10(9) M(-1) s(-1) was obtained, slightly faster than for the analogous 6-member ring containing antibiotics, (6.6 +/- 1.2) x 10(9) M(-1) s(-1). The consistency of these rate constants for each group infers a common reaction mechanism, consisting of the partitioning of the hydroxyl radical between addition to peripheral aromatic rings and reaction with the central double-ring core of these antibiotics.

  16. The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys

    Directory of Open Access Journals (Sweden)

    Wolf-Dieter Mueller

    2014-06-01

    Full Text Available Mg and Mg alloys are becoming more and more of interest for several applications. In the case of biomaterial applications, a special interest exists due to the fact that a predictable degradation should be given. Various investigations were made to characterize and predict the corrosion behavior in vitro and in vivo. Mostly, the simple oxidation of Mg to Mg2+ ions connected with adequate hydrogen development is assumed, and the negative difference effect (NDE is attributed to various mechanisms and electrochemical results. The aim of this paper is to compare the different views on the corrosion pathway of Mg or Mg alloys and to present a neglected pathway based on thermodynamic data as a guideline for possible reactions combined with experimental observations of a delay of visible hydrogen evolution during cyclic voltammetry. Various reaction pathways are considered and discussed to explain these results, like the stability of the Mg+ intermediate state, the stability of MgH2 and the role of hydrogen overpotential. Finally, the impact of MgH2 formation is shown as an appropriate base for the prediction of the degradation behavior and calculation of the corrosion rate of Mg and Mg alloys.

  17. Low-complexity full-rate transmission scheme with full diversity for two-path relay networks

    KAUST Repository

    Fareed, Muhammad Mehboob

    2015-04-01

    Existing full-rate transmission schemes for two-path relay networks typically cannot achieve full diversity while demanding high decoding complexity. In this paper, we present a novel low-complexity full-rate transmission scheme for two-path relay networks to harvest maximum achievable diversity. The proposed scheme adopts block transmission with small block size of four symbols, which greatly reduces the decoding complexity at the receiver. Through the performance analysis of the resulting two-path relay network in terms of the symbol error rate (SER) and diversity order, we show the proposed scheme can achieve full diversity order of four and mimic a 2 \\\\times 2 multiple-input multiple-output system. Simulations results are provided to validate the mathematical formulation. © 1967-2012 IEEE.

  18. Sn-doped ZnO nanopetal networks for efficient photocatalytic degradation of dye and gas sensing applications

    Science.gov (United States)

    Bhatia, Sonik; Verma, Neha; Bedi, R. K.

    2017-06-01

    Nowadays, tremendous increase in environmental issue is an alarming threat to the ecosystem. This paper reports, rapid synthesis and characterization for tin doped ZnO nanoparticles prepared by simple combustion method and doctor blade technique. The prepared nanoparticles were characterized by several techniques in terms of their morphological, structural, compositional, optical, photocatalytic and gas sensing properties. These detailed characterization confirmed that all the synthesized nanoparticles are well crystalline and having good optoelectronic properties. Herein, different concentrations of Sn (0.5 at. wt%, 1.0 at. wt%, 2.0 at. wt%, 3.0 at. wt%) were used as dopants (SZ1-SZ4). The morphology of synthesized technique confirmed that the petal-shaped nanoparticles has high surface area and are well crystalline. In order to develop smart and functional nano-device, the prepared powder was coated on glass substrate by doctor blade technique and fabricated device was sensed for ethanol and acetone gas at different operating temperatures (300-500̊C). It is noteworthy that morphology of the nanoparticles of the sensitive layer is maintained after different concentration of Sn. High sensitivity is the main cause of high surface area and tin doping. PL intensity near 598 nm of SZ3 is greater than other Sn-doped ZnO which indicates more oxygen vacancies of SZ3 is responsible for enhanced gas sensitivity and photocatalytic activity. The sensing performance showed 5% volume of ethanol and acetone and gases could be detected with sensitivity of 86.80% and 84.40% respectively. The mechanism for the improvement in the sensing properties can be explained with the surface adsorption theory. Sn-ZnO was used as photocatalyst for degradation of DR-31 dye. Optimum concentration of prepared nanoparticles (2.0 at. wt%) exhibits complete degradation of dye only in 60 min under UV irradiation.

  19. Sn-doped ZnO nanopetal networks for efficient photocatalytic degradation of dye and gas sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Bhatia, Sonik, E-mail: sonikbhatia@gmail.com [Department of Physics, Kanya Maha Vidyalaya, Vidyalaya Marg, Jalandhar, 144004 (India); Verma, Neha [Department of Physics, Kanya Maha Vidyalaya, Vidyalaya Marg, Jalandhar, 144004 (India); Bedi, R.K. [Satyam Institute of Engineering and Technology, Amritsar, 143107, Punjab (India)

    2017-06-15

    sensitivity and photocatalytic activity. The sensing performance showed 5% volume of ethanol and acetone and gases could be detected with sensitivity of 86.80% and 84.40% respectively. The mechanism for the improvement in the sensing properties can be explained with the surface adsorption theory. Sn–ZnO was used as photocatalyst for degradation of DR-31 dye. Optimum concentration of prepared nanoparticles (2.0 at. wt%) exhibits complete degradation of dye only in 60 min under UV irradiation.

  20. Adaptive predictions of the euro/złoty currency exchange rate using state space wavelet networks and forecast combinations

    Directory of Open Access Journals (Sweden)

    Brdyś Mietek A.

    2016-03-01

    Full Text Available The paper considers the forecasting of the euro/Polish złoty (EUR/PLN spot exchange rate by applying state space wavelet network and econometric forecast combination models. Both prediction methods are applied to produce one-trading-day-ahead forecasts of the EUR/PLN exchange rate. The paper presents the general state space wavelet network and forecast combination models as well as their underlying principles. The state space wavelet network model is, in contrast to econometric forecast combinations, a non-parametric prediction technique which does not make any distributional assumptions regarding the underlying input variables. Both methods can be used as forecasting tools in portfolio investment management, asset valuation, IT security and integrated business risk intelligence in volatile market conditions.

  1. Potential relocation of climatic environments suggests high rates of climate displacement within the North American protection network

    Science.gov (United States)

    Enric Batllori; Marc-Andre Parisien; Sean A. Parks; Max A. Moritz; Carol Miller

    2017-01-01

    Ongoing climate change may undermine the effectiveness of protected area networks in preserving the set of biotic components and ecological processes they harbor, thereby jeopardizing their conservation capacity into the future. Metrics of climate change, particularly rates and spatial patterns of climatic alteration, can help assess potential threats. Here, we perform...

  2. Changes in rumen microbiota composition and in situ degradation kinetics during the dry period and early lactation as affected by rate of increase of concentrate allowance.

    Science.gov (United States)

    Dieho, K; van den Bogert, B; Henderson, G; Bannink, A; Ramiro-Garcia, J; Smidt, H; Dijkstra, J

    2017-04-01

    Changes in rumen microbiota and in situ degradation kinetics were studied in 12 rumen-cannulated Holstein Friesian dairy cows during the dry period and early lactation. The effect of a rapid (RAP) or gradual (GRAD) postpartum (pp) rate of increase of concentrate allowance was also investigated. Cows were fed for ad libitum intake and had free access to a mixed ration consisting of chopped wheat straw (dry period only), grass silage, corn silage, and soybean meal. Treatment consisted of either a rapid (1.0 kg of dry matter/d; n = 6) or gradual (0.25 kg of dry matter/d; n = 6) increase of concentrate allowance (up to 10.9 kg of dry matter/d), starting at 4 d pp. In whole rumen contents, bacterial community composition was assessed using samples from 50, 30, and 10 d antepartum (ap), and 3, 9, 16, 30, 44, 60, and 80 d pp, and protozoal and archaeal community composition using samples from 10 d ap, and 16 and 44 d pp. Intake of fermentable organic matter, starch, and sugar was temporarily greater in RAP than GRAD at 16 d pp. Bacterial community richness was higher during the dry period than during the lactation. A rapid increase in concentrate allowance decreased bacterial community richness at 9 and 16 d pp compared with a gradual increase in concentrate allowance, whereas from 30 d pp onward richness of RAP and GRAD was similar. In general, the relative abundances of Bacteroidales and Aeromonadales were greater, and those of Clostridiales, Fibrobacterales, and Spirochaetales were smaller, during the lactation compared with the dry period. An interaction between treatment and sampling day was observed for some bacterial community members, and most of the protozoal and archaeal community members. Transition to lactation increased the relative abundance of Epidinium and Entodinium, but reduced the relative abundance of Ostracodinium. Archaea from genus Methanobrevibacter dominated during both the dry period and lactation. However, during lactation the abundance of the

  3. Selected aspects of modelling of foreign exchange rates with neural networks

    Directory of Open Access Journals (Sweden)

    Václav Mastný

    2005-01-01

    Full Text Available This paper deals with forecasting of the high-frequency foreign exchange market with neural networks. The objective is to investigate some aspects of modelling with neural networks (impact of topology, size of training set and time horizon of the forecast on the performance of the network. The data used for the purpose of this paper contain 15-minute time series of US dollar against other major currencies, Japanese Yen, British Pound and Euro. The results show, that performance of the network in terms of correct directorial change is negatively influenced by increasing number of hidden neurons and decreasing size of training set. The performance of the network is influenced by sampling frequency.

  4. Comparison of GPU- and CPU-implementations of mean-firing rate neural networks on parallel hardware.

    Science.gov (United States)

    Dinkelbach, Helge Ülo; Vitay, Julien; Beuth, Frederik; Hamker, Fred H

    2012-01-01

    Modern parallel hardware such as multi-core processors (CPUs) and graphics processing units (GPUs) have a high computational power which can be greatly beneficial to the simulation of large-scale neural networks. Over the past years, a number of efforts have focused on developing parallel algorithms and simulators best suited for the simulation of spiking neural models. In this article, we aim at investigating the advantages and drawbacks of the CPU and GPU parallelization of mean-firing rate neurons, widely used in systems-level computational neuroscience. By comparing OpenMP, CUDA and OpenCL implementations towards a serial CPU implementation, we show that GPUs are better suited than CPUs for the simulation of very large networks, but that smaller networks would benefit more from an OpenMP implementation. As this performance strongly depends on data organization, we analyze the impact of various factors such as data structure, memory alignment and floating precision. We then discuss the suitability of the different hardware depending on the networks' size and connectivity, as random or sparse connectivities in mean-firing rate networks tend to break parallel performance on GPUs due to the violation of coalescence.

  5. SBMLsqueezer: A CellDesigner plug-in to generate kinetic rate equations for biochemical networks

    Directory of Open Access Journals (Sweden)

    Schröder Adrian

    2008-04-01

    Full Text Available Abstract Background The development of complex biochemical models has been facilitated through the standardization of machine-readable representations like SBML (Systems Biology Markup Language. This effort is accompanied by the ongoing development of the human-readable diagrammatic representation SBGN (Systems Biology Graphical Notation. The graphical SBML editor CellDesigner allows direct translation of SBGN into SBML, and vice versa. For the assignment of kinetic rate laws, however, this process is not straightforward, as it often requires manual assembly and specific knowledge of kinetic equations. Results SBMLsqueezer facilitates exactly this modeling step via automated equation generation, overcoming the highly error-prone and cumbersome process of manually assigning kinetic equations. For each reaction the kinetic equation is derived from the stoichiometry, the participating species (e.g., proteins, mRNA or simple molecules as well as the regulatory relations (activation, inhibition or other modulations of the SBGN diagram. Such information allows distinctions between, for example, translation, phosphorylation or state transitions. The types of kinetics considered are numerous, for instance generalized mass-action, Hill, convenience and several Michaelis-Menten-based kinetics, each including activation and inhibition. These kinetics allow SBMLsqueezer to cover metabolic, gene regulatory, signal transduction and mixed networks. Whenever multiple kinetics are applicable to one reaction, parameter settings allow for user-defined specifications. After invoking SBMLsqueezer, the kinetic formulas are generated and assigned to the model, which can then be simulated in CellDesigner or with external ODE solvers. Furthermore, the equations can be exported to SBML, LaTeX or plain text format. Conclusion SBMLsqueezer considers the annotation of all participating reactants, products and regulators when generating rate laws for reactions. Thus, for

  6. Numerical Modeling of Variable Fluid Injection-Rate Modes on Fracturing Network Evolution in Naturally Fractured Formations

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2016-05-01

    Full Text Available In this study, variable injection-rate technology was numerically investigated in a pre-existing discrete fracture network (DFN formation, the Tarim Basin in China. A flow-stress-damage (FSD coupling model has been used in an initial attempt towards how reservoir response to variable injection-rates at different hydraulic fracturing stages. The established numerical model simultaneously considered the macroscopic and microscopic heterogeneity characteristics. Eight numerical cases were studied. Four cases were used to study the variable injection-rate technology, and the other four cases were applied for a constant injection-rate in order to compare with the variable injection-rate technology. The simulation results show that the variable injection-rate technology is a potentially good method to a form complex fracturing networks. The hydraulic fracturing effectiveness when increasing the injection-rate at each stage is the best, also, the total injected fluid is at a minimum. At the initial stage, many under-fracturing points appear around the wellbore with a relatively low injection-rate; the sudden increase of injection rate drives the dynamic propagation of hydraulic fractures along many branching fracturing points. However, the case with decreasing injection rate is the worst. By comparing with constant injection-rate cases, the hydraulic fracturing effectiveness with variable flow rate technology is generally better than those with constant injection-rate technology. This work strongly links the production technology and hydraulic fracturing effectiveness evaluation and aids in the understanding and optimization of hydraulic fracturing simulations in naturally fractured reservoirs.

  7. Precise calculation of a bond percolation transition and survival rates of nodes in a complex network.

    Science.gov (United States)

    Kawamoto, Hirokazu; Takayasu, Hideki; Jensen, Henrik Jeldtoft; Takayasu, Misako

    2015-01-01

    Through precise numerical analysis, we reveal a new type of universal loopless percolation transition in randomly removed complex networks. As an example of a real-world network, we apply our analysis to a business relation network consisting of approximately 3,000,000 links among 300,000 firms and observe the transition with critical exponents close to the mean-field values taking into account the finite size effect. We focus on the largest cluster at the critical point, and introduce survival probability as a new measure characterizing the robustness of each node. We also discuss the relation between survival probability and k-shell decomposition.

  8. Inorganic nanoparticles for the spatial and temporal control of organic reactions: Applications to radical degradation of biopolymer networks

    Science.gov (United States)

    Walker, Joan Marie

    Nanoparticles of gold and iron oxide not only possess remarkable optical and magnetic properties, respectively, but are also capable of influencing their local environment with an astounding degree of precision. Using nanoparticles to direct the reactivity of organic molecules near their surface provides a unique method of spatial and temporal control. Enediynes represent an exceptional class of compounds that are thermally reactive to produce a diradical intermediate via Bergman cycloaromatization. While natural product enediynes are famously cytotoxic, a rich chemistry of synthetic enediynes has developed utilizing creative means to control this reactivity through structure, electronics, metal chelation, and external triggering mechanisms. In a heretofore unexplored arena for Bergman cyclization, we have investigated the reactivity of enediynes in connection with inorganic nanoparticles in which the physical properties of the nanomaterial are directly excited to thermally promote aromatization. As the first example of this methodology, gold nanoparticles conjugated with (Z)-octa-4-en-2,6-diyne-1,8-dithiol were excited with 514 nm laser irradiation. The formation of aromatic and polymeric products was confirmed through Raman spectroscopy and electron microscopy. Water soluble analogues Au-PEG-EDDA and Fe3O4-PEG-EDDA (EDDA = (Z)-octa-4-en-2,6-diyne-1,8-diamine) show similar reactivity under laser irradiation or alternating magnetic field excitation, respectively. Furthermore, we have used these functionalized nanoparticles to attack proteinaceous substrates including fibrin and extracellular matrix proteins, capitalizing on the ability of diradicals to disrupt peptidic bonds. By delivering a locally high payload of reactive molecules and thermal energy to the large biopolymer, network restructuring and collapse is achieved. As a synthetic extension towards multifunctional nanoparticles, noble metal seed-decorated iron oxides have also been prepared and assessed for

  9. Social Network resources and self-rated health in a deprived Danish neighborhood

    DEFF Research Database (Denmark)

    Tanggaard Andersen, Pernille; Holst Algren, Maria; Fromsejer Heiberg, Regina

    2017-01-01

    by social network resources. This is the main aim of this article. Cross-sectional data from one deprived neighborhood located in Denmark were collected in 2008 and 2013 using a postal health survey. The target group was defined as adults older than 16 years. In 2008, 408 residents participated......Research has demonstrated that living in a deprived neighborhood contributes to the occurrence and development of poor health. Furthermore evidence shows that social networks are fundamental resources in preventing poor mental health. Neighborhood relationships and networks are vital for sustaining...... in the survey, and 405 residents participated in 2013. Our main explanatory variables were indicators of socioeconomic positions and social network resources. The analyses were conducted using univariate and bivariate analyses and multiple logistic regressions. The results showed that there was a significant...

  10. Network of photonic sensors for CO2 exchange rate measurement in forests

    Science.gov (United States)

    Sobotka, Piotr; Bieda, Marcin S.; Lesiak, Piotr; Woliński, Tomasz R.

    2017-08-01

    A network of photonic CO2 sensors based on distributed sensing elements that are spread around the tested ecosystem area is proposed. Each of the sensing elements is connected to a wireless network with adjacent sensing elements and a base station that collects, archives, and analyzes results of measurements. The sensing element includes a CO2 sensor module for data transmission as well as power supply module that analyzes speed and direction of flow of the air mass within the specified measurement point.

  11. Experimental Demonstration of Mixed Formats and Bit Rates Signal Allocation for Spectrum-flexible Optical Networking

    DEFF Research Database (Denmark)

    Borkowski, Robert; Karinou, Fotini; Angelou, Marianna

    2012-01-01

    We report on an extensive experimental study for adaptive allocation of 16-QAM and QPSK signals inside spectrum flexible heterogeneous superchannel. Physical-layer performance parameters are extracted for use in resource allocation mechanisms of future flexible networks.......We report on an extensive experimental study for adaptive allocation of 16-QAM and QPSK signals inside spectrum flexible heterogeneous superchannel. Physical-layer performance parameters are extracted for use in resource allocation mechanisms of future flexible networks....

  12. Meiofauna communities, nematode diversity and C degradation rates in seagrass (Posidonia oceanica L.) and unvegetated sediments invaded by the algae Caulerpa cylindracea (Sonder).

    Science.gov (United States)

    Pusceddu, Antonio; Fraschetti, Simona; Scopa, Mariaspina; Rizzo, Lucia; Danovaro, Roberto

    2016-08-01

    We investigated meiofauna and sedimentary C cycling in seagrass (Posidonia oceanica) and unvegetated sediments invaded and not invaded by the non-indigenous tropical algae Caulerpa cylindracea. In both habitats, invaded sediments were characterized by higher organic matter contents. No effect was observed for prokaryotes and C degradation rates. In seagrass sediments, C turnover in invaded beds was about half that in not invaded ones. Meiofaunal communities varied significantly among invaded and not invaded grounds only in bare sediments. In both habitats, nematode species richness and assemblage composition were not affected by the algae. The effect of C. cylindracea on the turnover and nestedness components of the Jaccard dissimilarity varied between the two habitats. We show that the presence of C. cylindracea gives rise to variable consequences on meiofauna biodiversity and C cycling in different habitats. We conclude that further studies across different habitats and ecological components are needed to ultimately understand and predict the consequences of C. cylindracea invasion in shallow Mediterranean ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. The association between network social capital and self-rated health: pouring old wine in new bottles?

    Science.gov (United States)

    Verhaeghe, Pieter-Paul; Pattyn, Elise; Bracke, Piet; Verhaeghe, Mieke; Van De Putte, Bart

    2012-03-01

    This study examines whether there is an association between network social capital and self-rated health after controlling for social support. Moreover, we distinguish between network social capital that emerges from strong ties and weak ties. We used a cross-sectional representative sample of 815 adults from the Belgian population. Social capital is measured with the position generator and perceived social support with the MOS Social Support-scale. Results suggest that network social capital is associated with self-rated health after adjustment for social support. Because different social classes have access to different sets of resources, resources of friends and family from the intermediate and higher service classes are beneficial for self-rated health, whereas resources of friends and family from the working class appear to be rather detrimental for self-rated health. From a health-promoting perspective, these findings indicate that policy makers should deal with the root causes of socioeconomic disadvantages in society. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Method and Apparatus for Predicting Unsteady Pressure and Flow Rate Distribution in a Fluid Network

    Science.gov (United States)

    Majumdar, Alok K. (Inventor)

    2009-01-01

    A method and apparatus for analyzing steady state and transient flow in a complex fluid network, modeling phase changes, compressibility, mixture thermodynamics, external body forces such as gravity and centrifugal force and conjugate heat transfer. In some embodiments, a graphical user interface provides for the interactive development of a fluid network simulation having nodes and branches. In some embodiments, mass, energy, and specific conservation equations are solved at the nodes, and momentum conservation equations are solved in the branches. In some embodiments, contained herein are data objects for computing thermodynamic and thermophysical properties for fluids. In some embodiments, the systems of equations describing the fluid network are solved by a hybrid numerical method that is a combination of the Newton-Raphson and successive substitution methods.

  15. Advances in the GRADE approach to rate the certainty in estimates from a network meta-analysis.

    Science.gov (United States)

    Brignardello-Petersen, Romina; Bonner, Ashley; Alexander, Paul E; Siemieniuk, Reed A; Furukawa, Toshi A; Rochwerg, Bram; Hazlewood, Glen S; Alhazzani, Waleed; Mustafa, Reem A; Murad, M Hassan; Puhan, Milo A; Schünemann, Holger J; Guyatt, Gordon H

    2018-01-01

    This article describes conceptual advances of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) working group guidance to evaluate the certainty of evidence (confidence in evidence, quality of evidence) from network meta-analysis (NMA). Application of the original GRADE guidance, published in 2014, in a number of NMAs has resulted in advances that strengthen its conceptual basis and make the process more efficient. This guidance will be useful for systematic review authors who aim to assess the certainty of all pairwise comparisons from an NMA and who are familiar with the basic concepts of NMA and the traditional GRADE approach for pairwise meta-analysis. Two principles of the original GRADE NMA guidance are that we need to rate the certainty of the evidence for each pairwise comparison within a network separately and that in doing so we need to consider both the direct and indirect evidence. We present, discuss, and illustrate four conceptual advances: (1) consideration of imprecision is not necessary when rating the direct and indirect estimates to inform the rating of NMA estimates, (2) there is no need to rate the indirect evidence when the certainty of the direct evidence is high and the contribution of the direct evidence to the network estimate is at least as great as that of the indirect evidence, (3) we should not trust a statistical test of global incoherence of the network to assess incoherence at the pairwise comparison level, and (4) in the presence of incoherence between direct and indirect evidence, the certainty of the evidence of each estimate can help decide which estimate to believe. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Degradation of copepod fecal pellets

    DEFF Research Database (Denmark)

    Poulsen, Louise K.; Iversen, Morten

    2008-01-01

    amount of fecal pellets. The total degradation rate of pellets by the natural plankton community of Oresund followed the phytoplankton biomass, with maximum degradation rate during the spring bloom (2.5 +/- 0.49 d(-1)) and minimum (0.52 +/- 0.14 d(-1)) during late winter. Total pellet removal rate ranged...

  17. Effects of correlated Gaussian noise on the mean firing rate and correlations of an electrically coupled neuronal network.

    Science.gov (United States)

    Sun, Xiaojuan; Perc, Matjaz; Lu, Qishao; Kurths, Jürgen

    2010-09-01

    In this paper, we examine the effects of correlated Gaussian noise on a two-dimensional neuronal network that is locally modeled by the Rulkov map. More precisely, we study the effects of the noise correlation on the variations of the mean firing rate and the correlations among neurons versus the noise intensity. Via numerical simulations, we show that the mean firing rate can always be optimized at an intermediate noise intensity, irrespective of the noise correlation. On the other hand, variations of the population coherence with respect to the noise intensity are strongly influenced by the ratio between local and global Gaussian noisy inputs. Biological implications of our findings are also discussed.

  18. Restructuring the crystalline cellulose hydrogen bond network enhances its depolymerization rate

    Science.gov (United States)

    Shishir P.S. Chundawat; Giovanni Bellesia; Nirmal Uppugundla; Leonardo da Costa Sousa; Dahai Gao; Albert M. Cheh; Umesh P. Agarwal; Christopher M. Bianchetti; George N. Phillips; Paul Langan; Venkatesh Balan; S. Gnanakaran; Bruce E. Dale

    2011-01-01

    Conversion of lignocellulose to biofuels is partly inefficient due to the deleterious impact of cellulose crystallinity on enzymatic saccharification. We demonstrate how the synergistic activity of cellulases was enhanced by altering the hydrogen bond network within crystalline cellulose fibrils. We provide a molecular-scale explanation of these phenomena through...

  19. Real-time automatic interpolation of ambient gamma dose rates from the Dutch radioactivity monitoring network

    NARCIS (Netherlands)

    Hiemstra, P.H.; Pebesma, E.J.; Twenhöfel, C.J.W.; Heuvelink, G.B.M.

    2009-01-01

    Detection of radiological accidents and monitoring the spread of the contamination is of great importance. Following the Chernobyl accident many European countries have installed monitoring networks to perform this task. Real-time availability of automatically interpolated maps showing the spread of

  20. A relative rate utility based distributed power allocation algorithm for Cognitive Radio Networks

    DEFF Research Database (Denmark)

    Mahmood, Nurul Huda; Øien, G.E.; Lundheim, L.

    2012-01-01

    In an underlay Cognitive Radio Network, multiple secondary users coexist geographically and spectrally with multiple primary users under a constraint on the maximum received interference power at the primary receivers. Given such a setting, one may ask "how to achieve maximum utility benefit...

  1. Clusters of reaction rates and concentrations in protein networks such as phosphotransferase system

    NARCIS (Netherlands)

    Hardin, H.M.; Zagaris, A.; Willms, A.R.; Westerhoff, H.V.

    2014-01-01

    To understand the functioning of living cells, it is often helpful or even necessary to exploit inherent timescale disparities and focus on long-term dynamic behaviour. In the present study, we explore this type of behaviour for the biochemical network of the phosphotransferase system. We show that,

  2. Clusters of reaction rates and concentrations in protein networks such as the phosphotransferase system

    NARCIS (Netherlands)

    Härdin, Hanna M.; Zagaris, Antonios; Willms, Allan R.; Westerhoff, Hans V.

    To understand the functioning of living cells, it is often helpful or even necessary to exploit inherent timescale disparities and focus on long-term dynamic behaviour. In the present study, we explore this type of behaviour for the biochemical network of the phosphotransferase system. We show that,

  3. Network 13 partnership to improve the influenza, pneumococcal pneumonia, and hepatitis B vaccination rates among dialysis patients.

    Science.gov (United States)

    Duval, Linda; George, Cheryl; Hedrick, Nellie; Woodruff, Sandra; Kleinpeter, Myra A

    2011-01-01

    Vaccinations are available for primary prevention of many infections in adults. Morbidity and mortality from invasive diseases such as influenza and Streptococcus pneumoniae (pneumococcus) remain high and may be largely preventable by vaccination of high-risk adults, including dialysis patients. The current 23-valent vaccine-efficacious, with a low adverse event profile-is widely available. Revaccination is also recommended in patients with immunocompromising conditions, including chronic kidney disease. Despite having many opportunities to be vaccinated, adult hemodialysis and peritoneal dialysis patients are often missed During the recent H1N1 influenza outbreak, we conducted a performance improvement project to increase the vaccination rates for pneumococcal pneumonia, hepatitis B, and influenza, with a special focus on prevention. The project included an education phase, baseline assessment of vaccination rates, intervention, and a follow-up assessment of vaccination rates. The geographic jurisdiction of ESRD Network 13 encompasses the states of Arkansas, Louisiana, and Oklahoma. At the beginning of the network-wide project, the documented state-specific rates for influenza immunization were below the average influenza immunization rates for adults reported by Centers for Disease Control and Prevention and far below its target for adults. Our improvement project incorporated educational interventions to improve patient acceptance of vaccinations, educational interventions to improve staff participation in quality improvement activities, and improved techniques of quality improvement data collection and analysis by participants. During this project, the immunization rates for hepatitis B and pneumococcal pneumonia were also reviewed. At project's conclusion, improvement was demonstrated in all three focus areas, with statistically significant improvements noted in both influenza and pneumococcus vaccination rates. The use of educational interventions to improve

  4. Traffic accident reconstruction and an approach for prediction of fault rates using artificial neural networks: A case study in Turkey.

    Science.gov (United States)

    Can Yilmaz, Ali; Aci, Cigdem; Aydin, Kadir

    2016-08-17

    Currently, in Turkey, fault rates in traffic accidents are determined according to the initiative of accident experts (no speed analyses of vehicles just considering accident type) and there are no specific quantitative instructions on fault rates related to procession of accidents which just represents the type of collision (side impact, head to head, rear end, etc.) in No. 2918 Turkish Highway Traffic Act (THTA 1983). The aim of this study is to introduce a scientific and systematic approach for determination of fault rates in most frequent property damage-only (PDO) traffic accidents in Turkey. In this study, data (police reports, skid marks, deformation, crush depth, etc.) collected from the most frequent and controversial accident types (4 sample vehicle-vehicle scenarios) that consist of PDO were inserted into a reconstruction software called vCrash. Sample real-world scenarios were simulated on the software to generate different vehicle deformations that also correspond to energy-equivalent speed data just before the crash. These values were used to train a multilayer feedforward artificial neural network (MFANN), function fitting neural network (FITNET, a specialized version of MFANN), and generalized regression neural network (GRNN) models within 10-fold cross-validation to predict fault rates without using software. The performance of the artificial neural network (ANN) prediction models was evaluated using mean square error (MSE) and multiple correlation coefficient (R). It was shown that the MFANN model performed better for predicting fault rates (i.e., lower MSE and higher R) than FITNET and GRNN models for accident scenarios 1, 2, and 3, whereas FITNET performed the best for scenario 4. The FITNET model showed the second best results for prediction for the first 3 scenarios. Because there is no training phase in GRNN, the GRNN model produced results much faster than MFANN and FITNET models. However, the GRNN model had the worst prediction results. The

  5. Balancing the Rates of New Bone Formation and Polymer Degradation Enhances Healing of Weight-Bearing Allograft/Polyurethane Composites in Rabbit Femoral Defects

    Science.gov (United States)

    2014-10-03

    Percutaneous vertebroplasty and kyphoplasty for the stand alone augmentation of osteoporosis induced ver tebral compression fractures: present status... induced progressive healing in vivo, as evidenced by an increase in new bone formation, as well as a decrease in residual allograft and polymer from 6...formation and induced approximately zero-order degradation of the polymer. The consequent bal- ance of new bone formation and polymer degradation re- sulted

  6. Diversity of reproduction rate supports cooperation in the prisoner's dilemma game on complex networks

    CERN Document Server

    Szolnoki, A; Szabó, G

    2008-01-01

    In human societies the probability of strategy adoption from a given person may be affected by the personal features. Now we investigate how an artificially imposed restricted ability to reproduce, overruling ones fitness, affects an evolutionary process. For this purpose we employ the evolutionary prisoner's dilemma game on different complex graphs. Reproduction restrictions can have a facilitative effect on the evolution of cooperation that sets in irrespective of particularities of the interaction network. Indeed, an appropriate fraction of less fertile individuals may lead to full supremacy of cooperators where otherwise defection would be widespread. By studying cooperation levels within the group of individuals having full reproduction capabilities, we reveal that the recent mechanism for the promotion of cooperation is conceptually similar to the one reported previously for scale-free networks. Our results suggest that the diversity in the reproduction capability, related to inherently different attitu...

  7. ANALISIS TRANSFER RATE PENAMBAHAN NODE PADA INFRASTRUKTUR MOBILE ADHOC NETWORK (MANET UNTUK FILE SERVER

    Directory of Open Access Journals (Sweden)

    Rudi Kurniawan

    2017-05-01

    Full Text Available Teknologi Wireless Network sudah lama ditemukan dan seiring waktu juga mengalami perkembangan, Namun sifat teknologi ini menggantungkan diri pada infrastruktur jaringan yang ada. Hal ini bias menjadi kelemahan tersendiri saat kondisi infrastruktur jaringan sedang mengalami gangguan, karena setiap komunikasi yang melewati infrastruktur jaringan tersebut tidak akan sampai pada tujuan. Teknologi jaringan Mobile Ad-hoc Network (MANET diciptakan sebagai antisipasi jika infrastruktur jaringan sedang mengalami gangguan. Dengan jaringan MANET sistem komunikasi yang dilakukan tidak membutuhkan infrastruktur jaringan karena tiap node pada jaringan tersebut bersifat mobile. Untuk menguji kemampuan MANET, pada penelitian ini akan menerapkan File Transfer Protocol (FTP sebagai media untuk melakukan komunikasi data file transfer yang diimplementasi pada jaringan MANET. Dari pengujian yang telah dilakukan diperoleh hasil bahwa File Transfer dapat berfungsi dengan baik saat diterapkan pada jaringan MANET.

  8. Father Absence, Social Networks, and Maternal Ratings of Child Health: Evidence from the 2013 Social Networks and Health Information Survey in Mexico.

    Science.gov (United States)

    Edelblute, Heather B; Altman, Claire E

    2018-01-19

    Objectives To bridge the literature on the effect of father absence, international migration, and social networks on child health, we assess the association between father absence and maternal ratings of child poor health (MCPH). Next we test whether social networks of immediate and extended kin mediate the relationship between fathers' absence and MCPH. Methods Nested logistic regression models predicting MCPH are estimated using the 2013 Social Networks and Health Information Survey, collected in a migrant-sending community in Guanajuato, Mexico. These unique data distinguish among father absence due to migration versus other reasons and between immediate and extended kin ties. Results Descriptive results indicate that 25% of children with migrant fathers are assessed as having poor health, more often than children with present (15.5%) or otherwise absent fathers (17.5%). In the multivariate models, fathers' absence is not predictive of MCPH. However, the presence of extended kin ties for the mother was associated with approximately a 50% reduction in the odds of MCPH. Additionally, mother's poor self-assessed health was associated with increased odds of MCPH while the presence of a co-resident adult lowered the odds of MCPH. In sensitivity analysis among children with migrant fathers, the receipt of paternal remittances lowered the odds of MCPH. Conclusions for Practice Social networks have a direct and positive association with MCPH rather than mediating the father absence-MCPH relationship. The presence of extended kin ties in the local community is salient for more favorable child health and should be considered in public health interventions aimed at improving child health.

  9. Sum rate maximization in the uplink of multi-cell OFDMA networks

    KAUST Repository

    Tabassum, Hina

    2012-10-03

    Resource allocation in orthogonal frequency division multiple access (OFDMA) networks plays an imperative role to guarantee the system performance. However, most of the known resource allocation schemes are focused on maximizing the local throughput of each cell, while ignoring the significant effect of inter-cell interference. This paper investigates the problem of resource allocation (i.e., subcarriers and powers) in the uplink of a multi-cell OFDMA network. The problem has a non-convex combinatorial structure and is known to be NP hard. Firstly, we investigate the upper and lower bounds to the average network throughput due to the inherent complexity of implementing the optimal solution. Later, a centralized sub-optimal resource allocation scheme is developed. We further develop less complex centralized and distributed schemes that are well-suited for practical scenarios. The computational complexity of all schemes has been analyzed and the performance is compared through numerical simulations. Simulation results demonstrate that the distributed scheme achieves comparable performance to the centralized resource allocation scheme in various scenarios. © 2011 IEEE.

  10. Calculating the Number of Cluster Heads Based on the Rate-Distortion Function in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Mingxin Yang

    2014-01-01

    Full Text Available Due to limited resources in wireless sensor nodes, energy efficiency is considered as one of the primary constraints in the design of the topology of wireless sensor networks (WSNs. Since data that are collected by wireless sensor nodes exhibit the characteristics of temporal association, data fusion has also become a very important means of reducing network traffic as well as eliminating data redundancy as far as data transmission is concerned. Another reason for data fusion is that, in many applications, only some of the data that are collected can meet the requirements of the sink node. In this paper, we propose a method to calculate the number of cluster heads or data aggregators during data fusion based on the rate-distortion function. In our discussion, we will first establish an energy consumption model and then describe a method for calculating the number of cluster heads from the point of view of reducing energy consumption. We will also show through theoretical analysis and experimentation that the network topology design based on the rate-distortion function is indeed more energy-efficient.

  11. Collaborative Event-Driven Coverage and Rate Allocation for Event Miss-Ratio Assurances in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Ozgur Sanli H

    2010-01-01

    Full Text Available Wireless sensor networks are often required to provide event miss-ratio assurance for a given event type. To meet such assurances along with minimum energy consumption, this paper shows how a node's activation and rate assignment is dependent on its distance to event sources, and proposes a practical coverage and rate allocation (CORA protocol to exploit this dependency in realistic environments. Both uniform event distribution and nonuniform event distribution are considered and the notion of ideal correlation distance around a clusterhead is introduced for on-duty node selection. In correlation distance guided CORA, rate assignment assists coverage scheduling by determining which nodes should be activated for minimizing data redundancy in transmission. Coverage scheduling assists rate assignment by controlling the amount of overlap among sensing regions of neighboring nodes, thereby providing sufficient data correlation for rate assignment. Extensive simulation results show that CORA meets the required event miss-ratios in realistic environments. CORA's joint coverage scheduling and rate allocation reduce the total energy expenditure by 85%, average battery energy consumption by 25%, and the overhead of source coding up to 90% as compared to existing rate allocation techniques.

  12. An energy-efficient rate adaptive media access protocol (RA-MAC) for long-lived sensor networks.

    Science.gov (United States)

    Hu, Wen; Chen, Quanjun; Corke, Peter; O'Rourke, Damien

    2010-01-01

    We introduce an energy-efficient Rate Adaptive Media Access Control (RA-MAC) algorithm for long-lived Wireless Sensor Networks (WSNs). Previous research shows that the dynamic and lossy nature of wireless communications is one of the major challenges to reliable data delivery in WSNs. RA-MAC achieves high link reliability in such situations by dynamically trading off data rate for channel gain. The extra gain that can be achieved reduces the packet loss rate which contributes to reduced energy expenditure through a reduced numbers of retransmissions. We achieve this at the expense of raw bit rate which generally far exceeds the application's link requirement. To minimize communication energy consumption, RA-MAC selects the optimal data rate based on the estimated link quality at each data rate and an analytical model of the energy consumption. Our model shows how the selected data rate depends on different channel conditions in order to minimize energy consumption. We have implemented RA-MAC in TinyOS for an off-the-shelf sensor platform (the TinyNode) on top of a state-of-the-art WSN Media Access Control Protocol, SCP-MAC, and evaluated its performance by comparing our implementation with the original SCP-MAC using both simulation and experiment.

  13. Ratings of Sovereign Risk and the Macroeconomics Fundamentals of the countries: a Study Using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Osvaldo Cândido da Silva Filho

    2009-05-01

    Full Text Available To minimize the consequences of asymmetric information, the sovereign risk ratings are instruments that constitute a key piece in the determination of credit market conditions, essential to the growth of developing countries like Brazil. In the present work we studied based on macroeconomics foundations, a classification to sovereign risk ratings realized by the ratings agencies finding the classification using Artificial Neural Networks. We observed homogeneity degree between the attributions of agencies and macroeconomics foundations in the countries of sample which four of foundations seem to be more directly connected with these attributions. After, in a comparative static exercise, we use the model to make simulations of scenarios of the credit external conditions for the Brazilian economy, changing the macroeconomics foundations which we noted that agencies expected for more per capita income increasing and decrease of public debt. (Full article in Portuguese only

  14. The association between social networks and self-rated risk of HIV infection among secondary school students in Moshi Municipality, Tanzania.

    Science.gov (United States)

    Lyimo, Elizabeth J; Todd, Jim; Richey, Lisa Ann; Njau, Bernard

    2013-01-01

    This study describes the social networks of secondary school students in Moshi Municipality, and their association with self-rated risk of human immunodeficiency virus (HIV) infection. A cross-sectional analytical study was conducted among 300 students aged 15-24 years in 5 secondary schools in Moshi, Tanzania. Bonding networks were defined as social groupings of students participating in activities within the school, while bridging networks were groups that included students participating in social groupings from outside of the school environs. A structured questionnaire was used to ask about participation in bonding and bridging social networks and self-rated HIV risk behavior. More participants participated in bonding networks (72%) than in bridging networks (29%). Participation in bridging networks was greater among females (25%) than males (12%, psexually experienced, and of these 62 (70%) considered themselves to be at low risk of HIV infection. Factors associated with self-rated risk of HIV included: type of school (psexually experienced (psex in the past three months (psexual partner (psexual intercourse (passociation between bonding and bridging social networks on self-rated risk of HIV among study participants. However, sexually experienced participants rated themselves at low risk of HIV infection despite practicing unsafe sex. Efforts to raise adolescents' self-awareness of risk of HIV infection through life skills education and HIV/acquired immunodeficiency syndrome risk reduction strategies may be beneficial to students in this at-risk group.

  15. GOP-based channel rate allocation using genetic algorithm for scalable video streaming over error-prone networks.

    Science.gov (United States)

    Fang, Tao; Chau, Lap-Pui

    2006-06-01

    In this paper, we address the problem of unequal error protection (UEP) for scalable video transmission over wireless packet-erasure channel. Unequal amounts of protection are allocated to the different frames (I- or P-frame) of a group-of-pictures (GOP), and in each frame, unequal amounts of protection are allocated to the progressive bit-stream of scalable video to provide a graceful degradation of video quality as packet loss rate varies. We use a genetic algorithm (GA) to quickly get the allocation pattern, which is hard to get with other conventional methods, like hill-climbing method. Theoretical analysis and experimental results both demonstrate the advantage of the proposed algorithm.

  16. Determining Methane Leak Locations and Rates with a Wireless Network Composed of Low-Cost, Printed Sensors

    Science.gov (United States)

    Smith, C. J.; Kim, B.; Zhang, Y.; Ng, T. N.; Beck, V.; Ganguli, A.; Saha, B.; Daniel, G.; Lee, J.; Whiting, G.; Meyyappan, M.; Schwartz, D. E.

    2015-12-01

    We will present our progress on the development of a wireless sensor network that will determine the source and rate of detected methane leaks. The targeted leak detection threshold is 2 g/min with a rate estimation error of 20% and localization error of 1 m within an outdoor area of 100 m2. The network itself is composed of low-cost, high-performance sensor nodes based on printed nanomaterials with expected sensitivity below 1 ppmv methane. High sensitivity to methane is achieved by modifying high surface-area-to-volume-ratio single-walled carbon nanotubes (SWNTs) with materials that adsorb methane molecules. Because the modified SWNTs are not perfectly selective to methane, the sensor nodes contain arrays of variously-modified SWNTs to build diversity of response towards gases with adsorption affinity. Methane selectivity is achieved through advanced pattern-matching algorithms of the array's ensemble response. The system is low power and designed to operate for a year on a single small battery. The SWNT sensing elements consume only microwatts. The largest power consumer is the wireless communication, which provides robust, real-time measurement data. Methane leak localization and rate estimation will be performed by machine-learning algorithms built with the aid of computational fluid dynamics simulations of gas plume formation. This sensor system can be broadly applied at gas wells, distribution systems, refineries, and other downstream facilities. It also can be utilized for industrial and residential safety applications, and adapted to other gases and gas combinations.

  17. Nutrients interaction investigation to improve Monascus purpureus FTC5391 growth rate using Response Surface Methodology and Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Mohamad, R.

    2013-01-01

    Full Text Available Aims: Two vital factors, certain environmental conditions and nutrients as a source of energy are entailed for successful growth and reproduction of microorganisms. Manipulation of nutritional requirement is the simplest and most effectual strategy to stimulate and enhance the activity of microorganisms. Methodology and Results: In this study, response surface methodology (RSM and artificial neural network (ANN were employed to optimize the carbon and nitrogen sources in order to improve growth rate of Monascus purpureus FTC5391,a new local isolate. The best models for optimization of growth rate were a multilayer full feed-forward incremental back propagation network, and a modified response surface model using backward elimination. The optimum condition for cell mass production was: sucrose 2.5%, yeast extract 0.045%, casamino acid 0.275%, sodium nitrate 0.48%, potato starch 0.045%, dextrose 1%, potassium nitrate 0.57%. The experimental cell mass production using this optimal condition was 21 mg/plate/12days, which was 2.2-fold higher than the standard condition (sucrose 5%, yeast extract 0.15%, casamino acid 0.25%, sodium nitrate 0.3%, potato starch 0.2%, dextrose 1%, potassium nitrate 0.3%. Conclusion, significance and impact of study: The results of RSM and ANN showed that all carbon and nitrogen sources tested had significant effect on growth rate (P-value < 0.05. In addition the use of RSM and ANN alongside each other provided a proper growth prediction model.

  18. Optimal JPWL Forward Error Correction Rate Allocation for Robust JPEG 2000 Images and Video Streaming over Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Benoit Macq

    2008-07-01

    Full Text Available Based on the analysis of real mobile ad hoc network (MANET traces, we derive in this paper an optimal wireless JPEG 2000 compliant forward error correction (FEC rate allocation scheme for a robust streaming of images and videos over MANET. The packet-based proposed scheme has a low complexity and is compliant to JPWL, the 11th part of the JPEG 2000 standard. The effectiveness of the proposed method is evaluated using a wireless Motion JPEG 2000 client/server application; and the ability of the optimal scheme to guarantee quality of service (QoS to wireless clients is demonstrated.

  19. The Association Between Social Networks and Self-rated risk of HIV Infection among Secondary School Students in Moshi Municipality, Tanzania.

    OpenAIRE

    Lyimo, EJ; Todd, J.; Richey, LA; B. Njau

    2014-01-01

    Abstract This study describes the social networks of secondary school students in Moshi Municipality, and their association with self-rated risk of human immunodeficiency virus (HIV) infection. A cross-sectional analytical study was conducted among 300 students aged 15-24 years in 5 secondary schools in Moshi, Tanzania. Bonding networks were defined as social groupings of students participating in activities within the school, while bridging networks were groups that included students partici...

  20. The association between social networks and self-rated risk of HIV infection among secondary school students in Moshi Municipality, Tanzania

    DEFF Research Database (Denmark)

    Lyimo, Elizabeth; Todd, Jim; Richey, Lisa Ann

    2013-01-01

    participants rated themselves at low risk of HIV infection despite practicing unsafe sex. Efforts to raise adolescents' self-awareness of risk of HIV infection through life skills education and HIV/acquired immunodeficiency syndrome risk reduction strategies may be beneficial to students in this at-risk group.......This study describes the social networks of secondary school students in Moshi Municipality, and their association with self-rated risk of human immunodeficiency virus (HIV) infection. A cross-sectional analytical study was conducted among 300 students aged 15–24 years in 5 secondary schools...... participation in bonding and bridging social networks and self-rated HIV risk behavior. More participants participated in bonding networks (72%) than in bridging networks (29%). Participation in bridging networks was greater among females (25%) than males (12%, p 

  1. Adaptive beamforming and rate control in real-time wireless sensor networks for QoS optimization

    Science.gov (United States)

    Hortos, William S.

    2011-06-01

    Quality-of-service (QoS) metrics for sensor types in a wireless sensor network (WSN) can be associated with metrics for multimedia that describe the quality of fused information, e.g., throughput, delay, jitter, packet error rate, information correlation, congestion, etc. These QoS metrics are typically set by the application layer of the protocol stack. Application-layer metrics, in turn, depend on the support from lower protocol layers: session, transport, network, data link (MAC), and physical. Protocol dependencies of QoS metrics motivate a cross-layer design approach to QoS optimization for heterogeneous sensor types in a WSN. Cross-layer interactions in the protocol are represented, in previous work by the author, by a set of concatenated parameters and resource levels. The "best" cross-layer designs that optimize QoS are established by applying the general theory of martingale representations to parameterized multivariate point processes (MVPPs) for discrete random events occurring in the WSN. Adaptive control of WSN behavior through cross-layer design is realized through parametric factorization of stochastic conditional rates of the MVPPs. Cross-layer parameters that optimize QoS are determined in solutions to stochastic dynamic programming conditions derived from models of transient flows of heterogeneous data. Adaptive transmit beamforming, simplified as sectored antennas, and rate control at sensor nodes are introduced to enhance the performance metrics of successful throughput, known as "goodput", congestion, capacity, etc. Adaptive antenna and rate controls are parametrized in realtime cross-layer models of WSN dynamics. Simulations demonstrate that adaptive antenna directionality and rate allocations improve overall QoS performance of a baseline design without such adaptation.

  2. Preparation and sonophotocatalytic performance of hierarchical Bi2WO6 structures and effects of various factors on the rate of Rhodamine B degradation.

    Science.gov (United States)

    Liang, Liuying; Tursun, Yalkunjan; Nulahong, Aisha; Dilinuer, Talifu; Tunishaguli, Awuti; Gao, Ge; Abulikemu, Abulizi; Okitsu, Kenji

    2017-11-01

    Hierarchical Bi2WO6 structures with high surface area were prepared in the presence of polyvinylpyrrolidone by using an optimized hydrothermal method. The samples prepared were characterized by X-ray diffraction, field-emission scanning electron microscopy and N2 adsorption-desorption technique. The results of these characterizations showed the formation of the hierarchical Bi2WO6 structures with high surface area (51m(2)/g). The degradation of Rhodamine B (RhB) with or without visible light was investigated under various experimental conditions to evaluate the sonophotocatalytic activity of the hierarchical Bi2WO6 structures. The result showed that the degradation efficiency was found to be in the following order: sonocatalysisdegradation of RhB was observed: the degradation ratio achieved about 99.5% at 40min. The mechanism of the sonophotocatalysis was also proposed. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Characterisation of anisotropic etching in KOH using network etch rate function model: influence of an applied potential in terms of microscopic properties

    NARCIS (Netherlands)

    Nguyen, Q.D.; Elwenspoek, Michael Curt

    2006-01-01

    Using the network etch rate function model, the anisotropic etch rate of p-type single crystal silicon was characterised in terms of microscopic properties including step velocity, step and terrace roughening. The anisotropic etch rate data needed have been obtained using a combination of 2 wagon

  4. Measuring Ionospheric Irregularities Globally by the Rate of TEC Index and GNSS Networks

    Science.gov (United States)

    Pi, Xiaoqing

    2012-01-01

    Outline of presentation: Why do we use the rate of TEC index (ROTI) instead of the standard s4 and sigma-phi indices? What are the differences between S4, sigma-phi and ROTI? Examples of ROTI measurements and Development status and plan.

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

    NARCIS (Netherlands)

    Durmaz, 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

  6. Achievable Rates of Cognitive Radio Networks Using Multi-Layer Coding with Limited CSI

    KAUST Repository

    Sboui, Lokman

    2016-03-01

    In a Cognitive Radio (CR) framework, the channel state information (CSI) feedback to the secondary transmitter (SU Tx) can be limited or unavailable. Thus, the statistical model is adopted in order to determine the system performance using the outage concept. In this paper, we adopt a new approach using multi-layer-coding (MLC) strategy, i.e., broadcast approach, to enhance spectrum sharing over fading channels. First, we consider a scenario where the secondary transmitter has no CSI of both the link between SU Tx and the primary receiver (cross-link) and its own link. We show that using MLC improves the cognitive rate compared to the rate provided by a singlelayer- coding (SLC). In addition, we observe numerically that 2-Layer coding achieves most of the gain for Rayleigh fading. Second, we analyze a scenario where SU Tx is provided by partial CSI about its link through quantized CSI. We compute its achievable rate adopting the MLC and highlight the improvement over SLC. Finally, we study the case in which the cross-link is perfect, i.e., a cooperative primary user setting, and compare the performance with the previous cases. We present asymptotic analysis at high power regime and show that the cooperation enhances considerably the cognitive rate at high values of the secondary power budget.

  7. Combined techniques for characterising pasta structure reveals how the gluten network slows enzymic digestion rate.

    Science.gov (United States)

    Zou, Wei; Sissons, Mike; Gidley, Michael J; Gilbert, Robert G; Warren, Frederick J

    2015-12-01

    The aim of the present study is to characterise the influence of gluten structure on the kinetics of starch hydrolysis in pasta. Spaghetti and powdered pasta were prepared from three different cultivars of durum semolina, and starch was also purified from each cultivar. Digestion kinetic parameters were obtained through logarithm-of-slope analysis, allowing identification of sequential digestion steps. Purified starch and semolina were digested following a single first-order rate constant, while pasta and powdered pasta followed two sequential first-order rate constants. Rate coefficients were altered by pepsin hydrolysis. Confocal microscopy revealed that, following cooking, starch granules were completely swollen for starch, semolina and pasta powder samples. In pasta, they were completely swollen in the external regions, partially swollen in the intermediate region and almost intact in the pasta strand centre. Gluten entrapment accounts for sequential kinetic steps in starch digestion of pasta; the compact microstructure of pasta also reduces digestion rates. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Artificial neural networks can learn to estimate extinction rates from molecular phylogenies

    NARCIS (Netherlands)

    Bokma, Folmer

    2006-01-01

    Molecular phylogenies typically consist of only extant species, yet they allow inference of past rates of extinction, because. recently originated species are less likely to be extinct than ancient species. Despite the simple structure of the assumed underlying speciation-extinction process,

  9. Gender differences in the association of perceived social support and social network with self-rated health status among older adults: a population-based study in Brazil

    National Research Council Canada - National Science Library

    Caetano, Silvana C; Silva, Cosme M F P; Vettore, Mario V

    2013-01-01

    .... Hence, the present study tests the hypothesis that gender differences exist in the relationship between perceived social support, social network, and self-rated health (SRH) among older adults...

  10. Photovoltaic Degradation Risk: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D. C.; Kurtz, S. R.

    2012-04-01

    The ability to accurately predict power delivery over the course of time is of vital importance to the growth of the photovoltaic (PV) industry. Important cost drivers include the efficiency with which sunlight is converted into power, how this relationship changes over time, and the uncertainty in this prediction. An accurate quantification of power decline over time, also known as degradation rate, is essential to all stakeholders - utility companies, integrators, investors, and researchers alike. In this paper we use a statistical approach based on historical data to quantify degradation rates, discern trends and quantify risks related to measurement uncertainties, number of measurements and methodologies.

  11. An Efficience Scheme to Reduce Burst Loss Rate and Supporting Differentiated Services in All-Optical Networks

    Science.gov (United States)

    Garg, Amit Kumar

    2011-06-01

    Due to their one-way resource reservation mechanism, Optical Burst Switching (OBS) networks experience high bursts (thus packets) loss rate. In OBS networks, the contention is resolved either by dropping one of the contending bursts or more efficiently by dropping from one of the contending bursts only the parts that overlap with the other bursts. In both situations, only one data source will suffer the data loss in favor to the other. In this paper, an efficient scheme to reduce burst loss rate has been proposed in conjunction with an appropriate mechanism to provide differentiated service in order to support the quality of service (QoS) requirements of different applications. Simulation results show that the performance of the proposed scheme is better than existing mechanisms in terms of reducing burst (packets) loss. Numerical results show that the proposed scheme provides an accurate fit for the performance of the highest traffic class and lower bounds for the other traffic classes that are tighter than earlier known results.

  12. Structural and functional social network attributes moderate the association of self-rated health with mental health in midlife and older adults.

    Science.gov (United States)

    Windsor, Tim D; Rioseco, Pilar; Fiori, Katherine L; Curtis, Rachel G; Booth, Heather

    2016-01-01

    Social relationships are multifaceted, and different social network components can operate via different processes to influence well-being. This study examined associations of social network structure and relationship quality (positive and negative social exchanges) with mental health in midlife and older adults. The focus was on both direct associations of network structure and relationship quality with mental health, and whether these social network attributes moderated the association of self-rated health (SRH) with mental health. Analyses were based on survey data provided by 2001 (Mean age = 65, SD = 8.07) midlife and older adults. We used Latent Class Analysis (LCA) to classify participants into network types based on network structure (partner status, network size, contact frequency, and activity engagement), and used continuous measures of positive and negative social exchanges to operationalize relationship quality. Regression analysis was used to test moderation. LCA revealed network types generally consistent with those reported in previous studies. Participants in more diverse networks reported better mental health than those categorized into a restricted network type after adjustment for age, sex, education, and employment status. Analysis of moderation indicated that those with poorer SRH were less likely to report poorer mental health if they were classified into more diverse networks. A similar moderation effect was also evident for positive exchanges. The findings suggest that both quantity and quality of social relationships can play a role in buffering against the negative implications of physical health decline for mental health.

  13. Application of an Artificial Neural Network to the Prediction of OH Radical Reaction Rate Constants for Evaluating Global Warming Potential.

    Science.gov (United States)

    Allison, Thomas C

    2016-03-03

    Rate constants for reactions of chemical compounds with hydroxyl radical are a key quantity used in evaluating the global warming potential of a substance. Experimental determination of these rate constants is essential, but it can also be difficult and time-consuming to produce. High-level quantum chemistry predictions of the rate constant can suffer from the same issues. Therefore, it is valuable to devise estimation schemes that can give reasonable results on a variety of chemical compounds. In this article, the construction and training of an artificial neural network (ANN) for the prediction of rate constants at 298 K for reactions of hydroxyl radical with a diverse set of molecules is described. Input to the ANN consists of counts of the chemical bonds and bends present in the target molecule. The ANN is trained using 792 (•)OH reaction rate constants taken from the NIST Chemical Kinetics Database. The mean unsigned percent error (MUPE) for the training set is 12%, and the MUPE of the testing set is 51%. It is shown that the present methodology yields rate constants of reasonable accuracy for a diverse set of inputs. The results are compared to high-quality literature values and to another estimation scheme. This ANN methodology is expected to be of use in a wide range of applications for which (•)OH reaction rate constants are required. The model uses only information that can be gathered from a 2D representation of the molecule, making the present approach particularly appealing, especially for screening applications.

  14. Design and Performance Investigation for the Optical Combinational Networks at High Data Rate

    Science.gov (United States)

    Tripathi, Devendra Kr.

    2017-05-01

    This article explores performance study for optical combinational designs based on nonlinear characteristics with semiconductor optical amplifier (SOA). Two configurations for optical half-adder with non-return-to-zero modulation pattern altogether with Mach-Zehnder modulator, interferometer at 50-Gbps data rate have been successfully realized. Accordingly, SUM and CARRY outputs have been concurrently executed and verified for their output waveforms. Numerical simulations for variation of data rate and key design parameters have been effectively executed outcome with optimum performance. Investigations depict overall good performance of the design in terms of the extinction factor. It also inferred that all-optical realization based on SOA is competent scheme, as it circumvents costly optoelectronic translation. This could be well supportive to erect larger complex optical combinational circuits.

  15. E-bra with nanosensors, smart electronics and smart phone communication network for heart rate monitoring

    Science.gov (United States)

    Varadan, Vijay K.; Kumar, Prashanth S.; Oh, Sechang; Mathur, Gyanesh N.; Rai, Pratyush; Kegley, Lauren

    2011-04-01

    Heart related ailments have been a major cause for deaths in both men and women in United States. Since 1985, more women than men have died due to cardiac or cardiovascular ailments for reasons that are not well understood as yet. Lack of a deterministic understanding of this phenomenon makes continuous real time monitoring of cardiovascular health the best approach for both early detection of pathophysiological changes and events indicative of chronic cardiovascular diseases in women. This approach requires sensor systems to be seamlessly mounted on day to day clothing for women. With this application in focus, this paper describes a e-bra platform for sensors towards heart rate monitoring. The sensors, nanomaterial or textile based dry electrodes, capture the heart activity signals in form Electrocardiograph (ECG) and relay it to a compact textile mountable amplifier-wireless transmitter module for relay to a smart phone. The ECG signal, acquired on the smart phone, can be transmitted to the cyber space for post processing. As an example, the paper discusses the heart rate estimation and heart rate variability. The data flow from sensor to smart phone to server (cyber infrastructure) has been discussed. The cyber infrastructure based signal post processing offers an opportunity for automated emergency response that can be initiated from the server or the smartphone itself. Detailed protocols for both the scenarios have been presented and their relevance to the present emergency healthcare response system has been discussed.

  16. Triangulation positioning system network

    Directory of Open Access Journals (Sweden)

    Sfendourakis Marios

    2017-01-01

    Full Text Available This paper presents ongoing work on localization and positioning through triangulation procedure for a Fixed Sensors Network - FSN.The FSN has to work as a system.As the triangulation problem becomes high complicated in a case with large numbers of sensors and transmitters, an adequate grid topology is needed in order to tackle the detection complexity.For that reason a Network grid topology is presented and areas that are problematic and need further analysis are analyzed.The Network System in order to deal with problems of saturation and False Triangulations - FTRNs will have to find adequate methods in every sub-area of the Area Of Interest - AOI.Also, concepts like Sensor blindness and overall Network blindness, are presented. All these concepts affect the Network detection rate and its performance and ought to be considered in a way that the network overall performance won’t be degraded.Network performance should be monitored contentiously, with right algorithms and methods.It is also shown that as the number of TRNs and FTRNs is increased Detection Complexity - DC is increased.It is hoped that with further research all the characteristics of a triangulation system network for positioning will be gained and the system will be able to perform autonomously with a high detection rate.

  17. DDE remediation and degradation.

    Science.gov (United States)

    Thomas, John E; Ou, Li-Tse; All-Agely, Abid

    2008-01-01

    breakdown of DDE by the extracellular lignolytic enzymes produced by white rot fungi. The addition of adjutants such as sodium ion, surfactants, and cellulose increased the rate of DDT aerobic or anaerobic degradation but did little to enhance the rate of DDE disappearance under anaerobic conditions. Only in the past decade has it been demonstrated that DDE can undergo reductive dechlorination under methanogenic and sulfidogenic conditions to form the degradation product DDMU, 1-chloro-2,2'-bis-(4'-chlorophenyl)ethane. The only pure culture reported to degrade DDE under anaerobic conditions was the denitrifier Alcaligens denitrificans. The degradation of DDE by this bacterium was enhanced by glucose, whereas biphenyl fumes had no effect. Abiotic remediation by DDE volatilization was enhanced by flooding and irrigation and deepplowing inhibited the volatilization. The use of zero-valent iron and surfactants in flooded soils enhanced DDT degradation but did not significantly alter the rate of DDE removal. Other catalysts (palladized magnesium, palladium on carbon, and nickel/aluminum alloys) degraded DDT and its metabolites, including DDE. However, these systems are often biphasic or involve explosive gases or both. Safer abiotic alternatives use UV light with titanium oxide or visible light with methylene green to degrade DDT, DDD, and DDE in aqueous or mixed solvent systems. Remediation and degradation of DDE in soil and water by phytoextraction, aerobic and anaerobic microorganisms, or abiotic methods can be accomplished. However, success has been limited, and great care must be taken that the method does not transfer the contaminants to another locale (by volatilization, deep plowing, erosion, or runoff) or to another species (by ingestion of accumulating plants or contaminated water). Although the remediation of DDT-, DDD-, and DDE-contaminated soil and water is beset with myriad problems, there remain many open avenues of research.

  18. Introduction to the High-Rate GPS Network of Puerto Rico and the U.S. Virgin Islands

    Science.gov (United States)

    Wang, G.; Hillebrandt, C. V.; Martinez, J. M.; Huerfano, V.; Schellekens, J.

    2008-12-01

    The Puerto Rico Seismic Network at the University of Puerto Rico at Mayagüez is a regional earthquake and tsunami monitoring institute. One of its primary objective is to provide timely and reliable earthquake and tsunami information and warning to the state (Puerto Rico) and local governments, the US and British Virgin Islands, as well as to the general public. In the past five years, it has been expanding its operations for the establishment of a Caribbean Tsunami Warning Center. With funding of the Puerto Rico government and NOAA, it is operated 24 hours per day and 7 days per week. Broadband seismometers are generally unable to capture the full bandwidth of long period ground motions following very large earthquakes. As a result, it is difficult to rapidly estimate the true magnitudes of large earthquakes using only seismic data. High-rate GPS has been justified as a very useful tool in recording long-period and permanent earthquake ground motions. Estimation of the true magnitude (and therefore tsunami potential) of large earthquakes may be determined more accurately in a timely manner (minutes after the quake) using high rate GPS observations. With the major aim of improving the ability of the PRSN in rapidly and precisely monitoring large earthquakes, NSF funded a Major Research Instrumentation (MRI) project, Acquisition of 9 High-rate GPS Units for Developing a Broadband Earthquake Observation System in Puerto Rico and the U.S. Virgin Islands (EAR-0722540, August 1, 2007-July 31, 2009). The major purpose of this project is to build a high-rate GPS network in Puerto Rico and the U.S. Virgin Islands. The GPS network includes 3 campaign and 6 permanent GPS stations. These campaign stations were designed to use in emergency response after large earthquakes to get co-seismic and post-seismic displacement. These six permanent stations were designed to complement current seismic observation system of Puerto Rico and U.S. Virgin Islands. We have installed three

  19. Lognormal firing rate distribution reveals prominent fluctuation-driven regime in spinal motor networks

    DEFF Research Database (Denmark)

    Petersen, Peter C.; Berg, Rune W.

    2016-01-01

    When spinal circuits generate rhythmic movements it is important that the neuronal activity remains within stable bounds to avoid saturation and to preserve responsiveness. Here, we simultaneously record from hundreds of neurons in lumbar spinal circuits of turtles and establish the neuronal...... fraction that operates within either a ‘mean-driven’ or a ‘fluctuation–driven’ regime. Fluctuation-driven neurons have a ‘supralinear’ input-output curve, which enhances sensitivity, whereas the mean-driven regime reduces sensitivity. We find a rich diversity of firing rates across the neuronal population...... as reflected in a lognormal distribution and demonstrate that half of the neurons spend at least 50 %% of the time in the ‘fluctuation–driven’ regime regardless of behavior. Because of the disparity in input–output properties for these two regimes, this fraction may reflect a fine trade–off between stability...

  20. A Linear Programming Approach to Routing Control in Networks of Constrained Nonlinear Positive Systems with Concave Flow Rates

    Science.gov (United States)

    Arneson, Heather M.; Dousse, Nicholas; Langbort, Cedric

    2014-01-01

    We consider control design for positive compartmental systems in which each compartment's outflow rate is described by a concave function of the amount of material in the compartment.We address the problem of determining the routing of material between compartments to satisfy time-varying state constraints while ensuring that material reaches its intended destination over a finite time horizon. We give sufficient conditions for the existence of a time-varying state-dependent routing strategy which ensures that the closed-loop system satisfies basic network properties of positivity, conservation and interconnection while ensuring that capacity constraints are satisfied, when possible, or adjusted if a solution cannot be found. These conditions are formulated as a linear programming problem. Instances of this linear programming problem can be solved iteratively to generate a solution to the finite horizon routing problem. Results are given for the application of this control design method to an example problem. Key words: linear programming; control of networks; positive systems; controller constraints and structure.

  1. Driving factors of interactions between the exchange rate market and the commodity market: A wavelet-based complex network perspective

    Science.gov (United States)

    Wen, Shaobo; An, Haizhong; Chen, Zhihua; Liu, Xueyong

    2017-08-01

    In traditional econometrics, a time series must be in a stationary sequence. However, it usually shows time-varying fluctuations, and it remains a challenge to execute a multiscale analysis of the data and discover the topological characteristics of conduction in different scales. Wavelet analysis and complex networks in physical statistics have special advantages in solving these problems. We select the exchange rate variable from the Chinese market and the commodity price index variable from the world market as the time series of our study. We explore the driving factors behind the behavior of the two markets and their topological characteristics in three steps. First, we use the Kalman filter to find the optimal estimation of the relationship between the two markets. Second, wavelet analysis is used to extract the scales of the relationship that are driven by different frequency wavelets. Meanwhile, we search for the actual economic variables corresponding to different frequency wavelets. Finally, a complex network is used to search for the transfer characteristics of the combination of states driven by different frequency wavelets. The results show that statistical physics have a unique advantage over traditional econometrics. The Chinese market has time-varying impacts on the world market: it has greater influence when the world economy is stable and less influence in times of turmoil. The process of forming the state combination is random. Transitions between state combinations have a clustering feature. Based on these characteristics, we can effectively reduce the information burden on investors and correctly respond to the government's policy mix.

  2. Optimal Policy of Cross-Layer Design for Channel Access and Transmission Rate Adaptation in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Jiang Zhu

    2010-01-01

    Full Text Available In this paper, we investigate the cross-layer design of joint channel access and transmission rate adaptation in CR networks with multiple channels for both centralized and decentralized cases. Our target is to maximize the throughput of CR network under transmission power constraint by taking spectrum sensing errors into account. In centralized case, this problem is formulated as a special constrained Markov decision process (CMDP, which can be solved by standard linear programming (LP method. As the complexity of finding the optimal policy by LP increases exponentially with the size of action space and state space, we further apply action set reduction and state aggregation to reduce the complexity without loss of optimality. Meanwhile, for the convenience of implementation, we also consider the pure policy design and analyze the corresponding characteristics. In decentralized case, where only local information is available and there is no coordination among the CR users, we prove the existence of the constrained Nash equilibrium and obtain the optimal decentralized policy. Finally, in the case that the traffic load parameters of the licensed users are unknown for the CR users, we propose two methods to estimate the parameters for two different cases. Numerical results validate the theoretic analysis.

  3. Nylon separators. [thermal degradation

    Science.gov (United States)

    Lim, H. S.

    1977-01-01

    A nylon separator was placed in a flooded condition in K0H solution and heated at various high temperatures ranging from 60 C to 110 C. The weight decrease was measured and the molecular weight and decomposition product were analyzed to determine: (1) the effect of K0H concentration on the hydrolysis rate; (2) the effect of K0H concentration on nylon degradation; (3) the activation energy at different K0H concentrations; and (4) the effect of oxygen on nylon degradation. The nylon hydrolysis rate is shown to increase as K0H concentration is decreased 34%, giving a maximum rate at about 16%. Separator hydrolysis is confirmed by molecular weight decrease in age of the batteries, and the reaction of nylon with molecular oxygen is probably negligible, compared to hydrolysis. The extrapolated rate value from the high temperature experiment correlates well with experimental values at 35 degrees.

  4. Supplementing energy and protein source at different rate of degradability to mixture of corn waste and coffee pod as basal diet on rumen fermentation kinetic of beef cattle

    Directory of Open Access Journals (Sweden)

    Dicky Pamungkas

    2010-03-01

    Full Text Available The use of corn waste and coffee pod as basal diet needs energy and protein supplementation in order to optimize rumen microbial growth. A research was done to study the appropriate supplement which is suitable based on the result of rumen fermentation kinetics. Four ruminally canulated cows, (205-224 kg of live weight were placed in individual cages. The basal diet (BD offered were corn waste and coffee pod mixture (80:20. Source of high degradable energy (HDE was cassava pomace; while the low degradable energy (LDE was arenga piñata waste. The high degradable protein (HDP was mixed-concentrate while the low degradable protein (LDP was leucaena leave meal. The supplementation of energy and protein to basal diet was in ratio of 50:50 based on dry matter. Feed offered were basal diet and the supplement at ratio of 60: 40 (3 % of LW. Observation was carried out for 4 periods (10 days/period. In each period, animal was fed one of the following diets: A = BD, B = BD+ HDE+LDP, C = BD+LDE+LDP, and D = BD+HDE+HDP. Rumen kinetics observed were: pH, and VFA, NH3 and rumen microbial protein concentrations. Rumen fluid was taken at the end of each period gradually along the course of 24 hours fermentation. The results showed that the diets gave significant effect (P < 0.05 on rumen pH. The lowest rumen pH (5.76 was observed on diet D at 2:00, 12 hours after feeding. Meanwhile, the highest pH (7.22 was found in animal fed diet A at 16:00. The total VFA on diet D of periode:1, 3 and 4 showed the highest level: 68.1 mmol/l; 75.37 mmol/l and 85.14 mmol/l respectively. The highest NH3 concentration was found in diet D followed by diet C, B and A. At 12:00 observation or at 4 h after morning feeding the highest NH3 was observed from diet D (41.94 mg/100 ml. It is concluded that diet D resulted in the best rumen fermentation kinetic, therefore it could be used in feed formulation in cattle diets.

  5. Stochastic Rating of Storage Systems in Isolated Networks with Increasing Wave Energy Penetration

    Directory of Open Access Journals (Sweden)

    Elisabetta Tedeschi

    2013-05-01

    Full Text Available The future success of wave energy in the renewable energy mix depends on the technical advancements of the specific components and systems, on the grid access availability and, ultimately, on the economical profitability of the investment. Small and remote islands represent an ideal framework for wave energy exploitation, due both to resource availability and to the current high cost of electricity that mostly relies on diesel generation. Energy storage can be the enabling technology to match the intermittent power generation from waves to the energy needs of the local community. In this paper real data from La Palma, in the Canary Islands, are used as a basis for the considered test case. As a first step the study quantifies the expected power production from Wave Energy Converter (WEC arrays, based on data from the Lifesaver point absorber developed by Fred. Olsen. Then, a stochastic optimization approach is applied to evaluate the convenience of energy storage introduction for reducing the final cost of energy and to define the corresponding optimal rating of the storage devices.

  6. Accelerating rate calorimetry study on the thermal stability of interpenetrating network type poly(siloxane-g-ethylene oxide) polymer electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Bookeun; Hyung, Yoo-Eup; Vissers, Donald R.; Amine, Khalil

    2003-06-30

    Safety study regarding an exothermic reaction at elevated temperature of comb-shaped siloxane polymer and its interpenetrating network type solid polymer electrolyte (SPE) are investigated. Accelerating rate calorimetry (ARC) is used to examine exothermic reactions. The thermal stability of the polymer electrolyte in the presence of charged electrodes is also monitored. Resulting data were compared with those of 1.0 M LiPF{sub 6} in ethylene carbonate:ethyl methyl carbonate (3:7 by wt.) electrolyte. The self-heating exothermic reaction of mono comb-shaped siloxane polymer electrolyte starts at approximately 300 deg. C. Comparison of the heat generation profiles from ARC tests indicates that SPE reduces the intensity of exothermic reactions resulting from charged electrodes and electrolyte.

  7. Total Phosphate Influences the Rate of Hydrocarbon Degradation but Phosphate Mineralogy Shapes Microbial Community Composition in Cold-Region Calcareous Soils.

    Science.gov (United States)

    Siciliano, Steven D; Chen, Tingting; Phillips, Courtney; Hamilton, Jordan; Hilger, David; Chartrand, Blaine; Grosskleg, Jay; Bradshaw, Kris; Carlson, Trevor; Peak, Derek

    2016-05-17

    Managing phosphorus bioaccessibility is critical for the bioremediation of hydrocarbons in calcareous soils. This paper explores how soil mineralogy interacts with a novel biostimulatory solution to both control phosphorus bioavailability and influence bioremediation. Two large bore infiltrators (1 m diameter) were installed at a PHC contaminated site and continuously supplied with a solution containing nutrients and an electron acceptor. Soils from eight contaminated sites were prepared and pretreated, analyzed pretrial, spiked with diesel, placed into nylon bags into the infiltrators, and removed after 3 months. From XAS, we learned that three principal phosphate phases had formed: adsorbed phosphate, brushite, and newberyite. All measures of biodegradation in the samples (in situ degradation estimates, mineralization assays, culturable bacteria, catabolic genes) varied depending upon the soil's phosphate speciation. Notably, adsorbed phosphate increased anaerobic phenanthrene degradation and bzdN catabolic gene prevalence. The dominant mineralogical constraints on community composition were the relative amounts of adsorbed phosphate, brushite, and newberyite. Overall, this study finds that total phosphate influences microbial community phenotypes whereas relative percentages of phosphate minerals influences microbial community genotype composition.

  8. Selective-TCP for wired/wireless networks

    OpenAIRE

    Paul, Rajashree

    2006-01-01

    One of the main reasons for TCP's degraded performance in wireless networks is TCP's interpretation that packet loss is caused by congestion. However, in wireless networks packet loss occurs mostly due to high bit error rate, packet corruption, or link failure. TCP performance in wired/wireless networks may be substantially improved if the cause of packet loss could be detected and appropriate rectifying measures taken dynamically. This report proposes a new end-to-end TCP protocol named Sele...

  9. Positive Rates of Preliminary Crossmatches Among Transplantation Candidates Waitlisted for Different Organs in the Korean Network for Organ Sharing.

    Science.gov (United States)

    Park, M H; Kim, S; Hwang, H; Park, H; Kwak, J; Kwon, E K; Sung, H Y; Han, B

    2016-09-01

    For deceased-donor organ transplantations, negative T cell crossmatches (XMs) are mandatory for kidney and pancreas allocation in the Korean Network for Organ Sharing (KONOS) organ allocation system. Submission and periodic renewal of serum to the KONOS is required for all transplantation candidates of kidney or pancreas and these sera are distributed to 23 laboratories for preliminary XMs. We have investigated how sensitization status varies among transplantation candidates waitlisted for different organs. Positive rates of T cell XMs performed during recent 1-year period (from March 2014 to February 2015) in the Korea Organ Donation Agency laboratory have been analyzed according to different organs. For 163 cases of deceased donors, 3605 recipients (22.1 recipients per one donor) were crossmatched using both of National Institutes of Health and antihuman globulin complement-dependent cytotoxicity (CDC) methods and flow cytometry method. T cell XM positive rates varied among transplantation candidates for different organs. The positive rate was high for kidney (485/3,145, 15.4%), and low for pancreas or kidney/pancreas (7/200, 3.5%), lung (0/41, 0%), and heart (11/221, 5.0%). Among XM-positive individuals, nearly two-thirds of the kidney transplantation candidates showed strong sensitization status with CDC+/flow+ results (64.5%), whereas pancreas or kidney/pancreas transplantation candidates more commonly showed weaker sensitization status with CDC-/flow+ results (85.7%). Kidney transplantation candidates show a much higher positive rate and stronger sensitization status than candidates for other organs. The results of this study would be useful for determining the number of candidates to be crossmatched for different organs. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Heating-Rate-Triggered Carbon-Nanotube-based 3-Dimensional Conducting Networks for a Highly Sensitive Noncontact Sensing Device

    KAUST Repository

    Tai, Yanlong

    2016-01-28

    Recently, flexible and transparent conductive films (TCFs) are drawing more attention for their central role in future applications of flexible electronics. Here, we report the controllable fabrication of TCFs for moisture-sensing applications based on heating-rate-triggered, 3-dimensional porous conducting networks through drop casting lithography of single-walled carbon nanotube (SWCNT)/poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) ink. How ink formula and baking conditions influence the self-assembled microstructure of the TCFs is discussed. The sensor presents high-performance properties, including a reasonable sheet resistance (2.1 kohm/sq), a high visible-range transmittance (>69%, PET = 90%), and good stability when subjected to cyclic loading (>1000 cycles, better than indium tin oxide film) during processing, when formulation parameters are well optimized (weight ratio of SWCNT to PEDOT:PSS: 1:0.5, SWCNT concentration: 0.3 mg/ml, and heating rate: 36 °C/minute). Moreover, the benefits of these kinds of TCFs were verified through a fully transparent, highly sensitive, rapid response, noncontact moisture-sensing device (5 × 5 sensing pixels).

  11. Rates of IUCD discontinuation and its associated factors among the clients of a social franchising network in Pakistan

    Directory of Open Access Journals (Sweden)

    Azmat Syed

    2012-03-01

    Full Text Available Abstract Background Modern Intrauterine contraceptive device (IUCD is very safe, highly effective reversible and inexpensive family planning method which offers 5-10 years of protection against pregnancy. The contraceptive use in Pakistan has been merely 30% for over a decade with IUCD being the least used method. Higher discontinuation rates are documented in developing countries; however no such data is available for Pakistan. Marie Stopes Society (MSS established a social franchise outlets network branded as 'SURAJ' (Sun in Pakistan to provide quality family planning services. This study attempts to determine IUCD discontinuation rates and its associated risk factors. Using a semi-structured questionnaire, a cross-sectional study was conducted with 3000 clients who availed IUCD services from Suraj provider 6, 12 and 24 month back,. Data were analyzed in SPSS 17.0; adjusted prevalence ratios were calculated to see associations between discontinuation and its risk factors. Case presentation We found that 22.7% of the IUCD acceptors experienced some health problem; while the overall discontinuation rate was 18.9% with average time of usage of 7.4 (SD ± 5.8 months before discontinuation. Half of them showed health concerns (49.8%; of which a majority (70.2% returned to Suraj provider for IUCD removal. Women living in Punjab, residing at a travelling time of 30-60 minutes and no previous use of contraceptive are more likely to discontinue IUCD. However, among total women 81.7% still expressed willingness to avail IUCD services from Suraj provider in future, if needed. Conclusion The findings suggest a need for training the providers and field workers to prevent early discontinuation of IUCD among the Suraj clients and by addressing the health concerns through proper counseling, continued follow-up and immediate medical aid/referral in case of complications.

  12. Effects of daily hemodialysis on heart rate variability: results from the Frequent Hemodialysis Network (FHN) Daily Trial.

    Science.gov (United States)

    Chan, Christopher T; Chertow, Glenn M; Daugirdas, John T; Greene, Tom H; Kotanko, Peter; Larive, Brett; Pierratos, Andreas; Stokes, John B

    2014-01-01

    End-stage renal disease is associated with reduced heart rate variability (HRV), components of which generally are associated with advanced age, diabetes mellitus and left ventricular hypertrophy. We hypothesized that daily in-center hemodialysis (HD) would increase HRV. The Frequent Hemodialysis Network (FHN) Daily Trial randomized 245 patients to receive 12 months of six versus three times per week in-center HD. Two hundred and seven patients had baseline Holter recordings. HRV measures were calculated from 24-h Holter electrocardiograms at both baseline and 12 months in 131 patients and included low-frequency power (LF, a measure of sympathetic modulation), high-frequency power (HF, a measure of parasympathetic modulation) and standard deviation (SD) of the R-R interval (SDNN, a measure of beat-to-beat variation). Baseline to Month 12 change in LF was augmented by 50% [95% confidence interval (95% CI) 6.1-112%, P =0.022] and LF + HF was augmented by 40% (95% CI 3.3-88.4%, P = 0.03) in patients assigned to daily hemodialysis (DHD) compared with conventional HD. Changes in HF and SDNN were similar between the randomized groups. The effects of DHD on LF were attenuated by advanced age and diabetes mellitus (predefined subgroups). Changes in HF (r = -0.20, P = 0.02) and SDNN (r = -0.18, P = 0.04) were inversely associated with changes in left ventricular mass (LVM). DHD increased the LF component of HRV. Reduction of LVM by DHD was associated with increased vagal modulation of heart rate (HF) and with increased beat-to-beat heart rate variation (SDNN), suggesting an important functional correlate to the structural effects of DHD on the heart in uremia.

  13. Feed-Forward Propagation of Temporal and Rate Information between Cortical Populations during Coherent Activation in Engineered In Vitro Networks.

    Science.gov (United States)

    DeMarse, Thomas B; Pan, Liangbin; Alagapan, Sankaraleengam; Brewer, Gregory J; Wheeler, Bruce C

    2016-01-01

    Transient propagation of information across neuronal assembles is thought to underlie many cognitive processes. However, the nature of the neural code that is embedded within these transmissions remains uncertain. Much of our understanding of how information is transmitted among these assemblies has been derived from computational models. While these models have been instrumental in understanding these processes they often make simplifying assumptions about the biophysical properties of neurons that may influence the nature and properties expressed. To address this issue we created an in vitro analog of a feed-forward network composed of two small populations (also referred to as assemblies or layers) of living dissociated rat cortical neurons. The populations were separated by, and communicated through, a microelectromechanical systems (MEMS) device containing a strip of microscale tunnels. Delayed culturing of one population in the first layer followed by the second a few days later induced the unidirectional growth of axons through the microtunnels resulting in a primarily feed-forward communication between these two small neural populations. In this study we systematically manipulated the number of tunnels that connected each layer and hence, the number of axons providing communication between those populations. We then assess the effect of reducing the number of tunnels has upon the properties of between-layer communication capacity and fidelity of neural transmission among spike trains transmitted across and within layers. We show evidence based on Victor-Purpura's and van Rossum's spike train similarity metrics supporting the presence of both rate and temporal information embedded within these transmissions whose fidelity increased during communication both between and within layers when the number of tunnels are increased. We also provide evidence reinforcing the role of synchronized activity upon transmission fidelity during the spontaneous synchronized

  14. Feed-Forward Propagation of Temporal and Rate Information between Cortical Populations during Coherent Activation in Engineered In Vitro Networks

    Science.gov (United States)

    DeMarse, Thomas B.; Pan, Liangbin; Alagapan, Sankaraleengam; Brewer, Gregory J.; Wheeler, Bruce C.

    2016-01-01

    Transient propagation of information across neuronal assembles is thought to underlie many cognitive processes. However, the nature of the neural code that is embedded within these transmissions remains uncertain. Much of our understanding of how information is transmitted among these assemblies has been derived from computational models. While these models have been instrumental in understanding these processes they often make simplifying assumptions about the biophysical properties of neurons that may influence the nature and properties expressed. To address this issue we created an in vitro analog of a feed-forward network composed of two small populations (also referred to as assemblies or layers) of living dissociated rat cortical neurons. The populations were separated by, and communicated through, a microelectromechanical systems (MEMS) device containing a strip of microscale tunnels. Delayed culturing of one population in the first layer followed by the second a few days later induced the unidirectional growth of axons through the microtunnels resulting in a primarily feed-forward communication between these two small neural populations. In this study we systematically manipulated the number of tunnels that connected each layer and hence, the number of axons providing communication between those populations. We then assess the effect of reducing the number of tunnels has upon the properties of between-layer communication capacity and fidelity of neural transmission among spike trains transmitted across and within layers. We show evidence based on Victor-Purpura’s and van Rossum’s spike train similarity metrics supporting the presence of both rate and temporal information embedded within these transmissions whose fidelity increased during communication both between and within layers when the number of tunnels are increased. We also provide evidence reinforcing the role of synchronized activity upon transmission fidelity during the spontaneous

  15. Design of multimodal degradable hydrogels for controlled therapeutic delivery

    Science.gov (United States)

    Kharkar, Prathamesh Madhav

    thiol exchange reaction facilitated rapid and responsive protein release in the presence of GSH. A photolabile o-nitrobenzyl ether group (o-NB) was subsequently incorporated within the PEG-based, gel-forming monomers to demonstrate cargo release triggered by exogenous stimuli for patient-specific therapies. Upon the application of cytocompatible doses of light, the photolabile o-NB linkage underwent irreversible cleavage yielding ketone and carboxylic acid-based cleavage products. Hydrogel degradation kinetics was characterized in response to externally applied cytocompatible light or GSH in aqueous microenvironments. By incorporating a photodegradable o-nitrobenzyl ether group, a thiol-sensitive succinimide thioether linkage, and ester linkages within the hydrogels, we demonstrated unique control over degradation via surface erosion or bulk degradation mechanisms, respectively, with degradation rate constants ranging from 10-1 min-1 to 10-4 min-1. As a proof of concept, the controlled release of nanobeads from the hydrogel was demonstrated in a preprogrammed and stimuli-responsive fashion. The multimodal degradable hydrogels were then investigated for the local controlled release of small molecular weight proteins, which are of interest for regulating various cellular functions and fates in vivo. Low molecular weight heparin, a highly sulfated polysaccharide was incorporated within the hydrogel network by Michael-type reaction due to its affinity with biologics such as growth factors and immunomodulatory proteins. Incorporation of reduction-sensitive linkages resulted in 2.3 fold differences in the release profile of fibroblast growth factor-2 (FGF-2) in the presence of GSH compared to non-reducing microenvironment. Bioactivity of released FGF-2 was comparable to pristine FGF-2, indicating the ability of the hydrogel to retain bioactivity of cargo molecules during encapsulation and release. Further, preliminary in vivo studies demonstrated control over hydrogel

  16. Degradation of CIGS solar cells

    OpenAIRE

    Theelen, M.J.

    2015-01-01

    Large scale commercial introduction of CIGS photovoltaics (PV) requires modules with low costs, high efficiencies and long and predictable lifetimes. Unfortunately,knowledge about the lifetime of CIGS PV is limited, which is reflected in the results of field studies: degradation rates varying from 0% to about 4% per year have been observed. Since warrantees are given out that the modules will still yield 80% of their initial power after 20 years of field exposure, degradation rates are often ...

  17. Tebuconazole photocatalytic degradation kinetics

    OpenAIRE

    Prestes, Thiago de Hermann; Gibbon, Danielle de Oliveira; Lansarin, Marla Azário; Moro, Celso Camilo

    2010-01-01

    The tebuconazole photocatalytic degradation kinetics was studied in a batch reactor using TiO2 (P25-Degussa) as catalyst and a high pressure mercury lamp. The photolysis, adsorption and irradiation effects in the reaction rate were evaluated. Afterward, the suspension catalyst concentration and initial pH to the maximum reaction rate was determined. It was observed that the reaction rate can be approached by a pseudo-first order, with a maximum kinetics constant at 260 mg L-1catalyst concentr...

  18. A Novel Dynamic Physical Layer Impairment-Aware Routing and Wavelength Assignment (PLI-RWA) Algorithm for Mixed Line Rate (MLR) Wavelength Division Multiplexed (WDM) Optical Networks

    Science.gov (United States)

    Iyer, Sridhar

    2016-12-01

    The ever-increasing global Internet traffic will inevitably lead to a serious upgrade of the current optical networks' capacity. The legacy infrastructure can be enhanced not only by increasing the capacity but also by adopting advance modulation formats, having increased spectral efficiency at higher data rate. In a transparent mixed-line-rate (MLR) optical network, different line rates, on different wavelengths, can coexist on the same fiber. Migration to data rates higher than 10 Gbps requires the implementation of phase modulation schemes. However, the co-existing on-off keying (OOK) channels cause critical physical layer impairments (PLIs) to the phase modulated channels, mainly due to cross-phase modulation (XPM), which in turn limits the network's performance. In order to mitigate this effect, a more sophisticated PLI-Routing and Wavelength Assignment (PLI-RWA) scheme needs to be adopted. In this paper, we investigate the critical impairment for each data rate and the way it affects the quality of transmission (QoT). In view of the aforementioned, we present a novel dynamic PLI-RWA algorithm for MLR optical networks. The proposed algorithm is compared through simulations with the shortest path and minimum hop routing schemes. The simulation results show that performance of the proposed algorithm is better than the existing schemes.

  19. N-Doped Porous Carbon Nanofibers/Porous Silver Network Hybrid for High-Rate Supercapacitor Electrode.

    Science.gov (United States)

    Meng, Qingshi; Qin, Kaiqiang; Ma, Liying; He, Chunnian; Liu, Enzuo; He, Fang; Shi, Chunsheng; Li, Qunying; Li, Jiajun; Zhao, Naiqin

    2017-09-13

    A three-dimensional cross-linked porous silver network (PSN) is fabricated by silver mirror reaction using polymer foam as the template. The N-doped porous carbon nanofibers (N-PCNFs) are further prepared on PSN by chemical vapor deposition and treated by ammonia gas subsequently. The PSN substrate serving as the inner current collector will improve the electron transport efficiency significantly. The ammonia gas can not only introduce nitrogen doping into PCNFs but also increase the specific surface area of PCNFs at the same time. Because of its large surface area (801 m2/g), high electrical conductivity (211 S/cm), and robust structure, the as-constructed N-PCNFs/PSN demonstrates a specific capacitance of 222 F/g at the current density of 100 A/g with a superior rate capability of 90.8% of its initial capacitance ranging from 1 to 100 A/g while applied as the supercapacitor electrode. The symmetric supercapacitor device based on N-PCNFs/PSN displays an energy density of 8.5 W h/kg with power density of 250 W/kg and excellent cycling stability, which attains 103% capacitance retention after 10 000 charge-discharge cycles at a high current density of 20 A/g, which indicates that N-PCNFs/PSN is a promising candidate for supercapacitor electrode materials.

  20. Wind Turbine Driving a PM Synchronous Generator Using Novel Recurrent Chebyshev Neural Network Control with the Ideal Learning Rate

    Directory of Open Access Journals (Sweden)

    Chih-Hong Lin

    2016-06-01

    Full Text Available A permanent magnet (PM synchronous generator system driven by wind turbine (WT, connected with smart grid via AC-DC converter and DC-AC converter, are controlled by the novel recurrent Chebyshev neural network (NN and amended particle swarm optimization (PSO to regulate output power and output voltage in two power converters in this study. Because a PM synchronous generator system driven by WT is an unknown non-linear and time-varying dynamic system, the on-line training novel recurrent Chebyshev NN control system is developed to regulate DC voltage of the AC-DC converter and AC voltage of the DC-AC converter connected with smart grid. Furthermore, the variable learning rate of the novel recurrent Chebyshev NN is regulated according to discrete-type Lyapunov function for improving the control performance and enhancing convergent speed. Finally, some experimental results are shown to verify the effectiveness of the proposed control method for a WT driving a PM synchronous generator system in smart grid.

  1. Linamarase production by some microbial isolates and a comparison of the rate of degradation of cassava cyanide by microbial and cassava linamarases

    Directory of Open Access Journals (Sweden)

    Ogbonnaya Nwokoro

    2016-01-01

    Full Text Available Production of linamarase and the effects of media composition on enzyme production were studied. A total of eight linamarase-producing bacteria were isolated from fermenting cassava tubers and soil samples. Selection of the isolates was based on their high growth in media containing 800 mg/L potassium cyanide solution. Eight of the isolates which showed very high growth in the growth medium as demonstrated by increase in their optical density readings to at least 0.6 in the cyanide containing media were selected for further studies. The isolates were identified as Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus amylovorus, Lactobacillus cellobiosus, Leuconostoc mesenteroides, Pseudomonas stutzeri, Bacillus pumilus and Bacillus subtilis. All the isolates were grown in media containing Tween 80 solution and in control media without the surfactant. Best enzyme activity of 6.82 U/mL was obtained in the medium containing Tween 80 solution and Lactobacillus fermentum as the test bacterium. Comparatively, linamarase production by the isolates in media without Tween 80 showed lower enzyme productivity. Cassava endogenous and microbial enzymes were tested for their abilities to hydrolyze cyanide in cassava flour samples pretreated to either remove the endogenous or microbial enzyme. Residual cyanide in cassava flour samples treated with linamarase of Lactobacillus plantarum was undecteded in 30 h, while in contrast, the residual cyanide in cassava flour samples treated with endogenous linamarase was 0.39 mg/10g cassava flour after 80 h. Residual cyanide in the untreated control sample was 1.98 mg HCN /10g cassava flour after 80 h. The results from this finding demonstrated improved cassava cyanide degradation with microbial linamarase as compared to endogenous cassava linamarase. Massive inoculation of fermenting cassava tubers with the isolates reported in this study would enable better control of the cassava fermentation process and may

  2. The National Ecological Observatory Network Aquatic Sampling: Dissolved Gas Concentrations, Stratification Conditions in Lakes, and Reaeration Rates in Streams

    Science.gov (United States)

    Cawley, K.; Goodman, K. J.

    2016-12-01

    The National Ecological Observatory Network (NEON) is deploying instrumentation and collecting samples on a continental spatial scale planned to operate for 30 years starting in 2018. There are five components of NEON: Airborne Observation Platform (AOP), Terrestrial Instrument System (TIS), Terrestrial Observation System (TOS), Aquatic Instrument System (AIS), and Aquatic Observation System (AOS). Collocation of measurements associated with each of these components will allow for linkage and comparison of data related to physical, chemical, and biological parameters. The NEON Aquatic subsystem, comprised of AOS and AIS, will quantify the impacts of climate change, land use, and biological invasions on freshwater populations and processes. Observations including organismal community composition, surface and groundwater chemistry, and habitat structure will be made in addition to deploying instrumentation in and around water bodies. Additionally, data processing is standardized, and quality-controlled data products derived from NEON measurements are freely available through the data portal. Some of the data that will be collected, processed, and published by NEON are particularly relevant to discovering connections between air, land and associated freshwaters, which drive the dynamics of carbon in inland waters. As part of the AOS sub-system, samples will be collected bi-weekly from 24 streams and monthly from 7 lakes for analysis of greenhouse gas (GHG) concentrations (CO2, N2O, and CH4). At the same time, depth profiles for temperature, conductivity, and dissolved oxygen will be collected in the lake sites. From these depth profiles, lake stratification conditions can be discerned. At stream sites, reaeration tracer experiments (simultaneous conservative and gas tracer injection) will be performed about 8 times per year. The stream reaeration rates will be related to discharge values to develop a rating curve from which temporally interpolated reaeration rates can

  3. Simulating light-weight Personalised Recommender Systems in Learning Networks: A case for Pedagogy-Oriented and Rating-based Hybrid Recommendation Strategies

    NARCIS (Netherlands)

    Nadolski, Rob; Van den Berg, Bert; Berlanga, Adriana; Drachsler, Hendrik; Hummel, Hans; Koper, Rob; Sloep, Peter

    2008-01-01

    Nadolski, R. J., Van den Berg, B., Berlanga, A. J., Drachsler, H., Hummel, H. G. K., Koper, R., & Sloep, P. B. (2009). Simulating Light-Weight Personalised Recommender Systems in Learning Networks: A Case for Pedagogy-Oriented and Rating-Based Hybrid Recommendation Strategies. Journal of Artificial

  4. Reconfigurable intensity modulation and direct detection optical transceivers for variable-rate wavelength-division-multiplexing passive optical networks utilizing digital signal processing-based symbol mapper

    Science.gov (United States)

    Zhang, Zhiguo; Zhang, Bingbing; Chen, Yanxu; Chen, Xue

    2017-01-01

    Variable-rate intensity modulation and direct detection-based optical transceivers with software-controllable reconfigurability and transmission performance adaptability are experimentally demonstrated, utilizing M-QAM symbol mapping implemented in MATLAB® programs. A frequency division multiplexing-based symbol demapping and wavelength management method is proposed for the symbol demapper and tunable laser management used in colorless optical network unit.

  5. Determination of 3D surface displacement rates in the Upper Rhine Graben based on GURN (GNSS Upper Rhine Graben Network)

    Science.gov (United States)

    Mayer, M.; Knöpfler, A.; Masson, F.; Ulrich, P.; Heck, B.

    2012-04-01

    In September 2008, the Institut de Physique du Globe de Strasbourg (Ecole et Observatoire des Sciences de la Terre) and the Geodetic Institute of Karlsruhe University (now: Karlsruhe Institute of Technology) established the transnational cooperation GURN (GNSS Upper Rhine Graben Network). Within the GURN initiative, these institutions are cooperating in order to carry out geo-scientific research in the framework of the transnational project TOPO-WECEP (Western and Central European Platform; link: http://www.topo-wecep.eu/), which succeeded the former project URGENT (Upper Rhine Graben Evolution and NeoTectonics; link: http://comp1.geol.unibas.ch) of the EUCOR universities (European Confederation of Upper Rhine Universities). The Rhine Graben is the central segment of the European Cenozoic rift system, which extends from the North Sea through Germany and France to the Mediterranean coast over a distance of some 1100 km. GURN focusses on the Upper Rhine Graben (URG). The URG is a 300 km long and 40 km wide SSW-NNE trending rift, extending from Basel (Switzerland) to Frankfurt (Germany). It is limited to the west by the Vosges Mountains and to the east by the Black Forest Mountains, culminating in elevations of approx. 1500 m. The uplifted area of the Rhenish Massif bounds the URG to the north. To the south, the Leymen, Ferrette, and Vendlincourt folds represent the northernmost structural front of the Jura fold and thrust belt. Present-day distribution of the seismicity in the URG area is classified as moderate but not null. Expected velocities and strain rates are very low (relative velocities lower than 0.1mm/yr). The research is actually based on data of GNSS (Global Navigation Satellite Systems). A highly precise and highly sensitive geodetic network of permanently operating GNSS sites region has been established in the URG region in order to detect recent short-term (data base starting in year 2002) crustal movements based on displacements of GNSS sites. The

  6. Robust PV Degradation Methodology and Application

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Deline, Christopher A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kurtz, Sarah [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kimball, Greg [SunPower; Anderson, Mike [SunPower

    2017-11-15

    The degradation rate plays an important role in predicting and assessing the long-term energy generation of PV systems. Many methods have been proposed for extracting the degradation rate from operational data of PV systems, but most of the published approaches are susceptible to bias due to inverter clipping, module soiling, temporary outages, seasonality, and sensor degradation. In this manuscript, we propose a methodology for determining PV degradation leveraging available modeled clear-sky irradiance data rather than site sensor data, and a robust year-over-year (YOY) rate calculation. We show the method to provide reliable degradation rate estimates even in the case of sensor drift, data shifts, and soiling. Compared with alternate methods, we demonstrate that the proposed method delivers the lowest uncertainty in degradation rate estimates for a fleet of 486 PV systems.

  7. Robust PV Degradation Methodology and Application

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Deline, Christopher A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kurtz, Sarah [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kimball, Gregory M. [SunPower Corporation; Anderson, Mike [SunPower Corporation

    2017-12-21

    The degradation rate plays an important role in predicting and assessing the long-term energy generation of photovoltaics (PV) systems. Many methods have been proposed for extracting the degradation rate from operational data of PV systems, but most of the published approaches are susceptible to bias due to inverter clipping, module soiling, temporary outages, seasonality, and sensor degradation. In this paper, we propose a methodology for determining PV degradation leveraging available modeled clear-sky irradiance data rather than site sensor data, and a robust year-over-year rate calculation. We show the method to provide reliable degradation rate estimates even in the case of sensor drift, data shifts, and soiling. Compared with alternate methods, we demonstrate that the proposed method delivers the lowest uncertainty in degradation rate estimates for a fleet of 486 PV systems.

  8. An investigation of link quality assessment for mobile multi-hop and multi-rate wireless networks

    NARCIS (Netherlands)

    Zhou, J.; Jacobsson, M.; Onur, E.; Niemegeers, I.

    2011-01-01

    Wireless ad hoc networks will be an important component in future communication systems. The performance of wireless ad hoc networks can be improved by link quality-aware applications. Wireless link quality is dynamic in nature, especially in mobile scenarios. Therefore, accurate and fast packet

  9. VADASE: a new approach for real-time fast displacement detection - First application to Taiwan High-Rate GNSS Network

    Science.gov (United States)

    Hung, Huang-Kai; Rau, Ruey-Juin; Colosimo, Gabriele; Benedetti, Elisa; Branzanti, Mara; Crespi, Mattia; Mazzoni, Augusto

    2014-05-01

    The aim of this work is to show new possibilities for GNSS Permanent Network data processing offered by VADASE (Variometric Approach for Displacements Analysis Standalone Engine) to retrieve waveforms and coseismic displacements in real-time when an earthquake occurs. The main advantage of using GNSS receiver, in a complementary way with traditional seismic network, is that it can work without being affected by saturation, which commonly influence seismometers and accelerometers close to strong earthquake epicenters. VADASE was originally proposed in 2010 ([4],[5]) as the third way in GPS Seismology (in addition to Precise Point Positioning and Instantaneous Differential Positioning). The approach is based on time single differences of carrier phase observations continuously collected at high rate (1 Hz or higher) using a standalone GPS receiver and standard GPS broadcast products (orbits and clocks) that are available in real-time. Hence, one receiver works in standalone mode and the epoch-by-epoch displacements (equivalent to velocities) are estimated. Then, they are summed over the time interval when the earthquake occurred to retrieve coseismic displacements and waveforms. Considering time intervals limited to few minutes, the receiver displacements can be ascertained at a few centimeters accuracy level in real-time. The effectiveness of this approach was recognized by DLR (German Aerospace Agency), and VADASE was awarded the DLR Special Topic Prize and the Audience Award at the European Satellite Navigation Competition 2010. Moreover, VADASE potential was proven in the dramatic occasion of the Japanese earthquake occurred on March 11, 2011 ([3]-[6]); in fact VADASE was able to provide the first estimates of the displacements suffered at the IGS sites of MIZU and USUD [7], as soon as the data of these stations were available. The results were then confirmed by several other solutions based on the renown (DP, PPP) approaches. More recently, VADASE was applied

  10. Outdoor PV Degradation Comparison

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D. C.; Smith, R. M.; Osterwald, C. R.; Gelak, E.; Kurtz, S. R.

    2011-02-01

    As photovoltaic (PV) penetration of the power grid increases, it becomes vital to know how decreased power output; may affect cost over time. In order to predict power delivery, the decline or degradation rates must be determined; accurately. At the Performance and Energy Rating Testbed (PERT) at the Outdoor Test Facility (OTF) at the; National Renewable Energy Laboratory (NREL) more than 40 modules from more than 10 different manufacturers; were compared for their long-term outdoor stability. Because it can accommodate a large variety of modules in a; limited footprint the PERT system is ideally suited to compare modules side-by-side under the same conditions.

  11. MaxHopCount: A New Drop Policy to Optimize Messages Delivery Rate in Delay Tolerant Networks

    Directory of Open Access Journals (Sweden)

    Youssef Harrati

    2016-09-01

    Full Text Available Communication has become a necessity, not only between every point on the earth, but also on the globe. That includes hard topography, highlands, underwater areas, and also space- crafts on other planets. However, the classic wired internet cannot be implemented in such areas, hence, researchers have invented wireless networks. The big challenge for wireless networking nowadays, is maintaining nodes connected in some difficult conditions, such as intermittent connectivity, power failure, and lot of obstacles for the interplanetary networks. In these challenging circumstances, a new networking model arises; it is Delay Tolerant networking which is based on the Store-Carry-and-Forward mechanism. Thus, a node may keep a message in its buffer for long periods of time; until a delivery or forward chance arises then it transmit it to other nodes. One of the big issues that confront this mechanism is the congestion of nodes buffer due to the big number of messages and the limited buffer size. Here, researchers have proposed buffer management algorithms in order to deal with the buffer overload problem, and they called it Drop Policies. In our present work, we propose a new Drop policy which we have compared to other existing policies in different conditions and with different routing protocols, and it always shows good result in term of number of delivered messages, network overhead and also average of latency.

  12. Artificial Neural Networks-Based Software for Measuring Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters.

    Science.gov (United States)

    Liu, Zhijian; Liu, Kejun; Li, Hao; Zhang, Xinyu; Jin, Guangya; Cheng, Kewei

    2015-01-01

    Measurements of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, conventional measurement requires expensive detection devices and undergoes a series of complicated procedures. To simplify the measurement and reduce the cost, software based on artificial neural networks for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters was developed. Using multilayer feed-forward neural networks with back-propagation algorithm, we developed and tested our program on the basis of 915 measured samples of water-in-glass evacuated tube solar water heaters. This artificial neural networks-based software program automatically obtained accurate heat collection rate and heat loss coefficient using simply "portable test instruments" acquired parameters, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, angle between tubes and ground and final temperature. Our results show that this software (on both personal computer and Android platforms) is efficient and convenient to predict the heat collection rate and heat loss coefficient due to it slow root mean square errors in prediction. The software now can be downloaded from http://t.cn/RLPKF08.

  13. Assessment of the trend of degradation of arable soils on the basis of data on the rate of stratozem development obtained with the use of 137Cs as a chronomarker

    Science.gov (United States)

    Golosov, V. N.; Ivanova, N. N.; Gusarov, A. V.; Sharifullin, A. G.

    2017-10-01

    A new approach for determining the trend of changes in the rate of degradation of arable soils is suggested. It is based on the assessment of volumes of soil material eroded from arable fields and accumulated on the bottoms of first-order valleys during two time intervals: 1954(1963)-1986 and 1986-2015. For dating of this material, 137Cs of global fallout and Chernobyl fallout are used. This approach in combination with a detailed morphometric characterization of the valley bottoms, the pathways of sediment transport from the fields, and the morphology and composition of the sediments accumulated on the bottoms makes it possible to give reliable estimates of the volumes of soil loss from tilled slopes. The benchmarks of 1963 and 1986 are related to maximum 137Cs fallout during nuclear bomb testing and immediately after the Chernobyl accident. As an example, the rates of formation of stratozems (stratified aggraded soils formed due to accumulation of eroded sediments) within the first-order catchment of the Veduga River basin (Voronezh oblast, Russia) are analyzed. The results of the study indicate that the mean annual rate of soil loss from arable fields of the catchment in 1986-2015 was at least two times lower than that in the preceding period from 1954 (the beginning of the global fallout) to 1986 (the Chernobyl accident).

  14. PROBLEMS OF DEGRADATION OF RECREATIONAL AND ENVIRONMENTAL AREAS OF THE CITY OF KYIV AND EVALUATION BIODIVERSITY LOSES IN THE CONTEXT OF FUTURE INTEGRATION INTO EU ECOLOGICAL NETWORK NATURA 2000

    Directory of Open Access Journals (Sweden)

    Derkulskyi R.

    2016-05-01

    Full Text Available Over the past decades the European Union has put in place a broad range of environmental legislation. As a result, air, water and soil pollution has significantly been reduced. Chemicals legislation has been modernised and the use of many toxic or hazardous substances has been restricted. Today, EU citizens enjoy some of the best water quality in the world and over 18% of EU's territory has been designated as protected areas for nature. On 9 November 2009 under the aegis of Eastern Partnership Platform “Economic Integration and Convergence with the EU Policies” there was established a Panel on the issues of environment and climate change. The Panel facilitates the information and good practices exchange on development and implementation of environmental and climate policies with the aim to promote the approximation of Eastern Partnership countries (includes Ukraine to the EU legislature in these spheres. The principles of ecological network system in Ukraine and the EU in the context of the EU Directive number 92/43 / EC are analyzed in this article. The necessary preconditions for Ukraine’s ecological network integration to the NATURA 2000 in the future should be: - establishment of Special Protection Areas (SPA’s on the principles of habitats and species protection; - amendments to legislation of Ukraine in terms of criteria ecological network definition. Biodiversity losses and degradation are identified in recreational and environmental areas of the city of Kyiv. Green areas in Kiev (especially parks has tendentions of lose their identity because of forest stand changes. The economic value of biodiversity should be factored into decision making in city planning, land management etc.

  15. Encapsulation of proteins in hydrogel carrier systems for controlled drug delivery: influence of network structure and drug size on release rate.

    Science.gov (United States)

    Bertz, Andreas; Wöhl-Bruhn, Stefanie; Miethe, Sebastian; Tiersch, Brigitte; Koetz, Joachim; Hust, Michael; Bunjes, Heike; Menzel, Henning

    2013-01-20

    Novel hydrogels based on hydroxyethyl starch modified with polyethylene glycol methacrylate (HES-P(EG)₆MA) were developed as delivery system for the controlled release of proteins. Since the drug release behavior is supposed to be related to the pore structure of the hydrogel network the pore sizes were determined by cryo-SEM, which is a mild technique for imaging on a nanometer scale. The results showed a decreasing pore size and an increase in pore homogeneity with increasing polymer concentration. Furthermore, the mesh sizes of the hydrogels were calculated based on swelling data. Pore and mesh size were significantly different which indicates that both structures are present in the hydrogel. The resulting structural model was correlated with release data for bulk hydrogel cylinders loaded with FITC-dextran and hydrogel microspheres loaded with FITC-IgG and FITC-dextran of different molecular size. The initial release depended much on the relation between hydrodynamic diameter and pore size while the long term release of the incorporated substances was predominantly controlled by degradation of the network of the much smaller meshes. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Rain rate and modeled fade distributions at 20 GHz and 30 GHz derived from five years of network rain gauge measurements

    Science.gov (United States)

    Goldhirsh, Julius; Krichevsky, Vladimir; Gebo, Norman

    1992-01-01

    Five years of rain rate and modeled slant path attenuation distributions at 20 GHz and 30 GHz derived from a network of 10 tipping bucket rain gages was examined. The rain gage network is located within a grid 70 km north-south and 47 km east-west in the Mid-Atlantic coast of the United States in the vicinity of Wallops Island, Virginia. Distributions were derived from the variable integration time data and from one minute averages. It was demonstrated that for realistic fade margins, the variable integration time results are adequate to estimate slant path attenuations at frequencies above 20 GHz using models which require one minute averages. An accurate empirical formula was developed to convert the variable integration time rain rates to one minute averages. Fade distributions at 20 GHz and 30 GHz were derived employing Crane's Global model because it was demonstrated to exhibit excellent accuracy with measured COMSTAR fades at 28.56 GHz.

  17. Anaerobic benzene degradation by bacteria

    Science.gov (United States)

    Vogt, Carsten; Kleinsteuber, Sabine; Richnow, Hans‐Hermann

    2011-01-01

    Summary Benzene is a widespread and toxic contaminant. The fate of benzene in contaminated aquifers seems to be primarily controlled by the abundance of oxygen: benzene is aerobically degraded at high rates by ubiquitous microorganisms, and the oxygen‐dependent pathways for its breakdown were elucidated more than 50 years ago. In contrast, benzene was thought to be persistent under anoxic conditions until 25 years ago. Nevertheless, within the last 15 years, several benzene‐degrading cultures have been enriched under varying electron acceptor conditions in laboratories around the world, and organisms involved in anaerobic benzene degradation have been identified, indicating that anaerobic benzene degradation is a relevant environmental process. However, only a few benzene degraders have been isolated in pure culture so far, and they all use nitrate as an electron acceptor. In some highly enriched strictly anaerobic cultures, benzene has been described to be mineralized cooperatively by two or more different organisms. Despite great efforts, the biochemical mechanism by which the aromatic ring of benzene is activated in the absence of oxygen is still not fully elucidated; methylation, hydroxylation and carboxylation are discussed as likely reactions. This review summarizes the current knowledge about the ‘key players’ of anaerobic benzene degradation under different electron acceptor conditions and the possible pathway(s) of anaerobic benzene degradation. PMID:21450012

  18. Dendrite-Free, High-Rate, Long-Life Lithium Metal Batteries with a 3D Cross-Linked Network Polymer Electrolyte.

    Science.gov (United States)

    Lu, Qingwen; He, Yan-Bing; Yu, Qipeng; Li, Baohua; Kaneti, Yusuf Valentino; Yao, Youwei; Kang, Feiyu; Yang, Quan-Hong

    2017-04-01

    A 3D network gel polymer electrolyte (3D-GPE) is designed for lithium metal batteries and prepared by an initiator-free one-pot ring-opening polymerization technique. This 3D-GPE exhibits an unprecedented combination of mechanical strength, ionic conductivity, and more importantly, effective suppression of Li dendrite growth. The produced lithium-based battery presents long life, high rate, and excellent safety. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. MQ NMR and SPME analysis of nonlinearity in the degradation of a filled silicone elastomer

    Energy Technology Data Exchange (ETDEWEB)

    Chinn, S C; Alviso, C T; Berman, E S; Harvey, C A; Maxwell, R S; Wilson, T S; Cohenour, R; Saalwachter, K; Chasse, W

    2008-10-10

    Radiation induced degradation of polymeric materials occurs via numerous, simultaneous, competing chemical reactions. Though degradation is typically found to be linear in adsorbed dose, some silicone materials exhibit non-linear dose dependence due to dose dependent dominant degradation pathways. We have characterized the effects of radiative and thermal degradation on a model filled-PDMS system, Sylgard 184 (commonly used as an electronic encapsulant and in biomedical applications), using traditional mechanical testing, NMR spectroscopy, and sample headspace analysis using Solid Phase Micro-Extraction (SPME) followed by Gas Chromatography/Mass Spectrometry (GC/MS). The mechanical data and {sup 1}H spin-echo NMR indicated that radiation exposure leads to predominantly crosslinking over the cumulative dose range studies (0 to 250 kGray) with a rate roughly linear with dose. {sup 1}H Multiple Quantum NMR detected a bimodal distribution in the network structure, as expected by the proposed structure of Sylgard 184. The MQ-NMR further indicated that the radiation induced structural changes were not linear in adsorbed dose and competing chain scission mechanisms contribute more largely to the overall degradation process in the range of 50 -100 kGray (though crosslinking still dominates). The SPME-GC/MS data were analyzed using Principal Component Analysis (PCA), which identified subtle changes in the distributions of degradation products (the cyclic siloxanes and other components of the material) as a function of age that provide insight into the dominant degradation pathways at low and high adsorbed dose.

  20. Degradation of chlorpyrifos in humid tropical soils.

    Science.gov (United States)

    Chai, Lian-Kuet; Wong, Mee-Hua; Bruun Hansen, Hans Christian

    2013-08-15

    The insecticide chlorpyrifos is extensively used in the humid tropics for insect control on crops and soils. Chlorpyrifos degradation and mineralization was studied under laboratory conditions to characterize the critical factors controlling the degradation and mineralization in three humid tropical soils from Malaysia. The degradation was fastest in moist soils (t1/2 53.3-77.0 days), compared to dry (t1/2 49.5-120 days) and wet soils (t1/2 63.0-124 days). Degradation increased markedly with temperature with activation energies of 29.0-76.5 kJ mol(-1). Abiotic degradation which is important for chlorpyrifos degradation in sub-soils containing less soil microbial populations resulted in t½ of 173-257 days. Higher chlorpyrifos dosages (5-fold) which are often applied in the tropics due to severe insects infestations caused degradation and mineralization rates to decrease by 2-fold. The mineralization rates were more sensitive to the chlorpyrifos application rates reflecting that degradation of metabolites is rate limiting and the toxic effects of some of the metabolites produced. Despite that chlorpyrifos is frequently used and often in larger amounts on tropical soils compared with temperate soils, higher temperature, moderate moisture and high activity of soil microorganisms will stimulate degradation and mineralization. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Estimating Rates of Permafrost Degradation and their Impact on Ecosystems across Alaska and Northwest Canada using the Process-based Permafrost Dynamics Model GIPL as a Component of the Integrated Ecosystem Model (IEM)

    Science.gov (United States)

    Marchenko, S. S.; Genet, H.; Euskirchen, E. S.; Breen, A. L.; McGuire, A. D.; Rupp, S. T.; Romanovsky, V. E.; Bolton, W. R.; Walsh, J. E.

    2016-12-01

    The impact of climate warming on permafrost and the potential of climate feedbacks resulting from permafrost thawing have recently received a great deal of attention. Permafrost temperature has increased in most locations in the Arctic and Sub-Arctic during the past 30-40 years. The typical increase in permafrost temperature is 1-3°C. The process-based permafrost dynamics model GIPL developed in the Geophysical Institute Permafrost Lab, and which is the permafrost module of the Integrated Ecosystem Model (IEM) has been using to quantify the nature and rate of permafrost degradation and its impact on ecosystems, infrastructure, CO2 and CH4fluxes and net C storage following permafrost thaw across Alaska and Northwest Canada. The IEM project is a multi-institutional and multi-disciplinary effort aimed at understanding potential landscape, habitat and ecosystem change across the IEM domain. The IEM project also aims to tie three scientific models together Terrestrial Ecosystem Model (TEM), the ALFRESCO (ALaska FRame-based EcoSystem Code) and GIPL so that they exchange data at run-time. The models produce forecasts of future fire, vegetation, organic matter, permafrost and hydrology regimes. The climate forcing data are based on the historical CRU3.1 data set for the retrospective analysis period (1901-2009) and the CMIP3 CCCMA-CGCM3.1 and MPI-ECHAM5/MPI-OM climate models for the future period (2009-2100). All data sets were downscaled to a 1 km resolution, using a differencing methodology (i.e., a delta method) and the Parameter-elevation Regressions on Independent Slopes Model (PRISM) climatology. We estimated the dynamics of permafrost temperature, active layer thickness, area occupied by permafrost, and volume of thawed soils across the IEM domain. The modeling results indicate how different types of ecosystems affect the thermal state of permafrost and its stability. Although the rate of soil warming and permafrost degradation in peatland areas are slower than

  2. Degradation of alachlor in aqueous solution by using hydrodynamic cavitation.

    Science.gov (United States)

    Wang, Xikui; Zhang, Yong

    2009-01-15

    The degradation of alachlor aqueous solution by using hydrodynamic cavitation was systematically investigated. It was found that alachlor in aqueous solution can be deomposed with swirling jet-induced cavitation. The degradation can be described by a pseudo-first-order kinetics and the degradation rate was found to be 4.90x10(-2)min(-1). The effects of operating parameters such as fluid pressure, solution temperature, initial concentration of alachlor and medium pH on the degradation rates of alachlor were also discussed. The results showed that the degradation rates of alachlor increased with increasing pressure and decreased with increasing initial concentration. An optimum temperature of 40 degrees C existed for the degradation rate of alachlor and the degradation rate was also found to be slightly depend on medium pH. Many degradation products formed during the process, and some of them were qualitatively identified by GC-MS.

  3. Working session 1: Tubing degradation

    Energy Technology Data Exchange (ETDEWEB)

    Kharshafdjian, G. [Atomic Energy of Canada, Mississauga, Ontario (Canada); Turluer, G. [IPSN, Fontenay-aux-Roses (France)

    1997-02-01

    A general introductory overview of the purpose of the group and the general subject area of SG tubing degradation was given by the facilitator. The purpose of the session was described as to {open_quotes}develop conclusions and proposals on regulatory and technical needs required to deal with the issues of SG tubing degradation.{close_quotes} Types, locations and characteristics of tubing degradation in steam generators were briefly reviewed. The well-known synergistic effects of materials, environment, and stress and strain/strain rate, subsequently referred to by the acronym {open_quotes}MESS{close_quotes} by some of the group members, were noted. The element of time (i.e., evolution of these variables with time) was emphasized. It was also suggested that the group might want to consider the related topics of inspection capabilities, operational variables, degradation remedies, and validity of test data, and some background information in these areas was provided. The presentation given by Peter Millet during the Plenary Session was reviewed; Specifically, the chemical aspects and the degradation from the secondary side of the steam generator were noted. The main issues discussed during the October 1995 EPRI meeting on secondary side corrosion were reported, and a listing of the potential SG tube degradations was provided and discussed.

  4. Degradation of CIGS solar cells

    NARCIS (Netherlands)

    Theelen, M.J.

    2015-01-01

    Large scale commercial introduction of CIGS photovoltaics (PV) requires modules with low costs, high efficiencies and long and predictable lifetimes. Unfortunately,knowledge about the lifetime of CIGS PV is limited, which is reflected in the results of field studies: degradation rates varying from

  5. The benefits of soft sensor and multi-rate control for the implementation of Wireless Networked Control Systems.

    Science.gov (United States)

    Mansano, Raul K; Godoy, Eduardo P; Porto, Arthur J V

    2014-12-18

    Recent advances in wireless networking technology and the proliferation of industrial wireless sensors have led to an increasing interest in using wireless networks for closed loop control. The main advantages of Wireless Networked Control Systems (WNCSs) are the reconfigurability, easy commissioning and the possibility of installation in places where cabling is impossible. Despite these advantages, there are two main problems which must be considered for practical implementations of WNCSs. One problem is the sampling period constraint of industrial wireless sensors. This problem is related to the energy cost of the wireless transmission, since the power supply is limited, which precludes the use of these sensors in several closed-loop controls. The other technological concern in WNCS is the energy efficiency of the devices. As the sensors are powered by batteries, the lowest possible consumption is required to extend battery lifetime. As a result, there is a compromise between the sensor sampling period, the sensor battery lifetime and the required control performance for the WNCS. This paper develops a model-based soft sensor to overcome these problems and enable practical implementations of WNCSs. The goal of the soft sensor is generating virtual data allowing an actuation on the process faster than the maximum sampling period available for the wireless sensor. Experimental results have shown the soft sensor is a solution to the sampling period constraint problem of wireless sensors in control applications, enabling the application of industrial wireless sensors in WNCSs. Additionally, our results demonstrated the soft sensor potential for implementing energy efficient WNCS through the battery saving of industrial wireless sensors.

  6. The Benefits of Soft Sensor and Multi-Rate Control for the Implementation of Wireless Networked Control Systems

    Directory of Open Access Journals (Sweden)

    Raul K. Mansano

    2014-12-01

    Full Text Available Recent advances in wireless networking technology and the proliferation of industrial wireless sensors have led to an increasing interest in using wireless networks for closed loop control. The main advantages of Wireless Networked Control Systems (WNCSs are the reconfigurability, easy commissioning and the possibility of installation in places where cabling is impossible. Despite these advantages, there are two main problems which must be considered for practical implementations of WNCSs. One problem is the sampling period constraint of industrial wireless sensors. This problem is related to the energy cost of the wireless transmission, since the power supply is limited, which precludes the use of these sensors in several closed-loop controls. The other technological concern in WNCS is the energy efficiency of the devices. As the sensors are powered by batteries, the lowest possible consumption is required to extend battery lifetime. As a result, there is a compromise between the sensor sampling period, the sensor battery lifetime and the required control performance for the WNCS. This paper develops a model-based soft sensor to overcome these problems and enable practical implementations of WNCSs. The goal of the soft sensor is generating virtual data allowing an actuation on the process faster than the maximum sampling period available for the wireless sensor. Experimental results have shown the soft sensor is a solution to the sampling period constraint problem of wireless sensors in control applications, enabling the application of industrial wireless sensors in WNCSs. Additionally, our results demonstrated the soft sensor potential for implementing energy efficient WNCS through the battery saving of industrial wireless sensors.

  7. 3D Networked Tin Oxide/Graphene Aerogel with a Hierarchically Porous Architecture for High-Rate Performance Sodium-Ion Batteries.

    Science.gov (United States)

    Xie, Xiuqiang; Chen, Shuangqiang; Sun, Bing; Wang, Chengyin; Wang, Guoxiu

    2015-09-07

    Low-cost and sustainable sodium-ion batteries are regarded as a promising technology for large-scale energy storage and conversion. The development of high-rate anode materials is highly desirable for sodium-ion batteries. The optimization of mass transport and electron transfer is crucial in the discovery of electrode materials with good high-rate performances. Herein, we report the synthesis of 3 D interconnected SnO2 /graphene aerogels with a hierarchically porous structure as anode materials for sodium-ion batteries. The unique 3 D architecture was prepared by a facile in situ process, during which cross-linked 3 D conductive graphene networks with macro-/meso-sized hierarchical pores were formed and SnO2 nanoparticles were dispersed uniformly on the graphene surface simultaneously. Such a 3 D functional architecture not only facilitates the electrode-electrolyte interaction but also provides an efficient electron pathway within the graphene networks. When applied as anode materials in sodium-ion batteries, the as-prepared SnO2 /graphene aerogel exhibited high reversible capacity, improved cycling performance compared to SnO2 , and promising high-rate capability. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Crustal velocity and strain rate fields in the Balearic Islands based on continuous GPS time series from the XGAIB network (2010-2013)

    Science.gov (United States)

    Sánchez-Alzola, Alberto; Sánchez, Carlos; Giménez, Jordi; Alfaro, Pedro; Gelabert, Bernadí; Borque, María J.; Gil, Antonio J.

    2014-12-01

    In this paper, we present a first estimation, using the GIPSY-OASIS software, of the crustal velocity and strain rate fields in the Balearic Islands (Spain), based on continuous GPS observations from the XGAIB network spanning the period 2010-2013. The XGAIB network consists of nine permanent, widely distributed stations that have operated continuously since 2010. In this paper, we describe the XGAIB network and the CGPS data processing and present our principle results in terms of the position time series and velocities of all of the sites, which were observed for more than three and a half years. In addition, strain tensors were estimated from the velocity field to obtain the first realistic crustal deformation model of the archipelago. The strains exhibit gradual variation across the Balearic Islands, from WNW-ESE extension in the southwest (Ibiza and Formentera) to NW-SE compression in the northeast (Menorca). These results constitute an advance in our knowledge of the tectonics of the western Mediterranean region.

  9. Appropriateness of Dropout Layers and Allocation of Their 0.5 Rates across Convolutional Neural Networks for CIFAR-10, EEACL26, and NORB Datasets

    Directory of Open Access Journals (Sweden)

    Romanuke Vadim V.

    2017-12-01

    Full Text Available A technique of DropOut for preventing overfitting of convolutional neural networks for image classification is considered in the paper. The goal is to find a rule of rationally allocating DropOut layers of 0.5 rate to maximise performance. To achieve the goal, two common network architectures are used having either 4 or 5 convolutional layers. Benchmarking is fulfilled with CIFAR-10, EEACL26, and NORB datasets. Initially, series of all admissible versions for allocation of DropOut layers are generated. After the performance against the series is evaluated, normalized and averaged, the compromising rule is found. It consists in non-compactly inserting a few DropOut layers before the last convolutional layer. It is likely that the scheme with two or more DropOut layers fits networks of many convolutional layers for image classification problems with a plenty of features. Such a scheme shall also fit simple datasets prone to overfitting. In fact, the rule “prefers” a fewer number of DropOut layers. The exemplary gain of the rule application is roughly between 10 % and 50 %.

  10. Alternative splicing of c-fos pre-mRNA: contribution of the rates of synthesis and degradation to the copy number of each transcript isoform and detection of a truncated c-Fos immunoreactive species

    Directory of Open Access Journals (Sweden)

    Pueyo Carmen

    2007-09-01

    Full Text Available Abstract Background Alternative splicing is a widespread mechanism of gene expression regulation. Previous analyses based on conventional RT-PCR reported the presence of an unspliced c-fos transcript in several mammalian systems. Compared to the well-defined knowledge on the alternative splicing of fosB, the physiological relevance of the unspliced c-fos transcript in regulating c-fos expression remains largely unknown. This work aimed to investigate the functional significance of the alternative splicing c-fos pre-mRNA. Results A set of primers was designed to demonstrate that, whereas introns 1 and 2 are regularly spliced from primary c-fos transcript, intron 3 remains unspliced in part of total transcript molecules. Here, the two species are referred to as c-fos-2 (+ intron 3 and spliced c-fos (- intron 3 transcripts. Then, we used a quantitatively rigorous approach based on real-time PCR to provide, for the first time, the actual steady-state copy numbers of the two c-fos transcripts. We tested how the mouse-organ context and mouse-gestational age, the synthesis and turnover rates of the investigated transcripts, and the serum stimulation of quiescent cells modulate their absolute-expression profiles. Intron 3 generates an in-frame premature termination codon that predicts the synthesis of a truncated c-Fos protein. This prediction was evaluated by immunoaffinity chromatography purification of c-Fos proteins. Conclusion We demonstrate that: (i The c-fos-2 transcript is ubiquitously synthesized either in vivo or in vitro, in amounts that are higher or similar to those of mRNAs coding for other Fos family members, like FosB, ΔFosB, Fra-1 or Fra-2. (ii Intron 3 confers to c-fos-2 an outstanding destabilizing effect of about 6-fold. (iii Major determinant of c-fos-2 steady-state levels in cultured cells is its remarkably high rate of synthesis. (iv Rapid changes in the synthesis and/or degradation rates of both c-fos transcripts in serum

  11. Sum-rate maximization and robust beamforming design for MIMO two-way relay networks with reciprocal and imperfect CSI

    National Research Council Canada - National Science Library

    Duan, Wei; Wen, Miaowen; Jiang, Xueqin; Yan, Yier; Ho Lee, Moon

    2016-01-01

    ...). In order to maximize the sum-rate (SR) subject to the individual relay power constraint, we first equivalently convert the objective problem into a sum of the inverse of the signal-to-residual-interference-plus-noise ratio (SI-SRINR) problem...

  12. PEM fuel cell degradation

    Energy Technology Data Exchange (ETDEWEB)

    Borup, Rodney L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory

    2010-01-01

    The durability of PEM fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. While significant progress has been made in understanding degradation mechanisms and improving materials, further improvements in durability are required to meet commercialization targets. Catalyst and electrode durability remains a primary degradation mode, with much work reported on understanding how the catalyst and electrode structure degrades. Accelerated Stress Tests (ASTs) are used to rapidly evaluate component degradation, however the results are sometimes easy, and other times difficult to correlate. Tests that were developed to accelerate degradation of single components are shown to also affect other component's degradation modes. Non-ideal examples of this include ASTs examining catalyst degradation performances losses due to catalyst degradation do not always well correlate with catalyst surface area and also lead to losses in mass transport.

  13. Achievable rate maximization for decode-and-forward MIMO-OFDM networks with an energy harvesting relay.

    Science.gov (United States)

    Du, Guanyao; Yu, Jianjun

    2016-01-01

    This paper investigates the system achievable rate for the multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system with an energy harvesting (EH) relay. Firstly we propose two protocols, time switching-based decode-and-forward relaying (TSDFR) and a flexible power splitting-based DF relaying (PSDFR) protocol by considering two practical receiver architectures, to enable the simultaneous information processing and energy harvesting at the relay. In PSDFR protocol, we introduce a temporal parameter to describe the time division pattern between the two phases which makes the protocol more flexible and general. In order to explore the system performance limit, we discuss the system achievable rate theoretically and formulate two optimization problems for the proposed protocols to maximize the system achievable rate. Since the problems are non-convex and difficult to solve, we first analyze them theoretically and get some explicit results, then design an augmented Lagrangian penalty function (ALPF) based algorithm for them. Numerical results are provided to validate the accuracy of our analytical results and the effectiveness of the proposed ALPF algorithm. It is shown that, PSDFR outperforms TSDFR to achieve higher achievable rate in such a MIMO-OFDM relaying system. Besides, we also investigate the impacts of the relay location, the number of antennas and the number of subcarriers on the system performance. Specifically, it is shown that, the relay position greatly affects the system performance of both protocols, and relatively worse achievable rate is achieved when the relay is placed in the middle of the source and the destination. This is different from the MIMO-OFDM DF relaying system without EH. Moreover, the optimal factor which indicates the time division pattern between the two phases in the PSDFR protocol is always above 0.8, which means that, the common division of the total transmission time into two equal phases in

  14. Comparison of Urinary Tract Infection Rates Associated with Transurethral Catheterization, Suprapubic Tube and Clean Intermittent Catheterization in the Postoperative Setting: A Network Meta-Analysis.

    Science.gov (United States)

    Han, Christopher S; Kim, Sinae; Radadia, Kushan D; Zhao, Philip T; Elsamra, Sammy E; Olweny, Ephrem O; Weiss, Robert E

    2017-12-01

    We performed a network meta-analysis of available randomized, controlled trials to elucidate the risks of urinary tract infection associated with transurethral catheterization, suprapubic tubes and intermittent catheterization in the postoperative setting. PubMed®, EMBASE® and Google Scholar™ searches were performed for eligible randomized, controlled trials from January 1980 to July 2015 that included patients who underwent transurethral catheterization, suprapubic tube placement or intermittent catheterization at the time of surgery and catheterization lasting up to postoperative day 30. The primary outcome of comparison was the urinary tract infection rate via a network meta-analysis with random effects model using the netmeta package in R 3.2 (www.r-project.org/). Included in analysis were 14 randomized, controlled trials in a total of 1,391 patients. Intermittent catheterization and suprapubic tubes showed no evidence of decreased urinary tract infection rates compared to transurethral catheterization. Suprapubic tubes and intermittent catheterization had comparable urinary tract infection rates (OR 0.903, 95% CI 0.479-2.555). On subgroup analysis of 10 randomized, controlled trials with available mean catheterization duration data in a total of 928 patients intermittent catheterization and suprapubic tube were associated with significantly decreased risk of urinary tract infection compared to transurethral catheterization when catheterization duration was greater than 5 days (OR 0.173, 95% CI 0.073-0.412 and OR 0.142, 95% CI 0.073-0.276, respectively). Transurethral catheterization is not associated with an increased urinary tract infection risk compared to suprapubic tubes and intermittent catheterization if catheterization duration is 5 days or less. However, a suprapubic tube or intermittent catheterization is associated with a lower rate of urinary tract infection if longer term catheterization is expected in the postoperative period. Copyright

  15. Surface Air Temperature Fluctuations and Lapse Rates on Olivares Gamma Glacier, Rio Olivares Basin, Central Chile, from a Novel Meteorological Sensor Network

    Directory of Open Access Journals (Sweden)

    Edward Hanna

    2017-01-01

    Full Text Available Empirically based studies of glacier meteorology, especially for the Southern Hemisphere, are relatively sparse in the literature. Here, we use an innovative network of highly portable, low-cost thermometers to report on high-frequency (1-min time resolution surface air temperature fluctuations and lapse rates (LR in a ~800-m elevational range (from 3,675 to 4,492 m a.s.l. across the glacier Olivares Gamma in the central Andes, Chile. Temperatures were measured during an intense field campaign in late Southern summer, 19–27 March 2015, under varying weather conditions. We found a complex dependence of high-frequency LR on time of day, topography, and wider meteorological conditions, with hourly temperature variations during this week that were probably mainly associated with short- and long-wave radiation changes and not with wind speed/direction changes. Using various pairs of sites within our station network, we also analyze spatial variations in LR. Uniquely in this study, we compare temperatures measured at heights of 1-m and 2-m above the glacier surface for the network of five sites and found that temperatures at these two heights occasionally differed by more than ±4°C during the early afternoons, although the mean temperature difference is much smaller (~0.3°C. An implication of our results is that daily, hourly, or even monthly averaged LR may be insufficient for feeding into accurate melt models of glacier change, with the adoption of subhourly (ideally 1–10-min resolution LR likely to prove fruitful in developing new innovative high-time-resolution melt modelling. Our results are potentially useful as input LR for local glacier melt models and for improving the understanding of lapse rate fluctuations and glacier response to climate change.

  16. Photocatalytic degradation of explosives contaminated water.

    Science.gov (United States)

    Lee, S J; Son, H S; Lee, H K; Zoh, K D

    2002-01-01

    This study was undertaken to examine the degradation of TNT, RDX and HMX in a circular photocatalytic reactor with TiO2 as a photocatalyst. We examined the impact of parameters such as the initial concentration, initial pH of solution on rates of photocatalized transformation, and the mineralization. The results showed that photocatalysis is an effective process for the degradation of TNT, RDX and HMX. They could be comoletely degraded in 150 min with 1.0 g/L TiO2 at pH 7. An increase in the photocatalytic degradation of HMX was noticed with decreasing initial HMX. The rates of RDX and HMX degradation were greater in neutral pH than in acidic and alkaline conditions. In case of TNT degradation, the rate of degradation was the fastest at pH 11. Approximately 82% TOC decrease in the TNT degradation was achieved after 150 min, whereas TOC decrease in RDX and HMX was 24% and 59%, respectively. Nitrate, nitrite, and ammonium ions were detected as the nitrogen byproducts from the photocatalysis, and more than 50% of the total nitrogen was recovered as nitrate ion in every explosives.

  17. The performance analysis of linux networking - packet receiving

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wenji; Crawford, Matt; Bowden, Mark; /Fermilab

    2006-11-01

    The computing models for High-Energy Physics experiments are becoming ever more globally distributed and grid-based, both for technical reasons (e.g., to place computational and data resources near each other and the demand) and for strategic reasons (e.g., to leverage equipment investments). To support such computing models, the network and end systems, computing and storage, face unprecedented challenges. One of the biggest challenges is to transfer scientific data sets--now in the multi-petabyte (10{sup 15} bytes) range and expected to grow to exabytes within a decade--reliably and efficiently among facilities and computation centers scattered around the world. Both the network and end systems should be able to provide the capabilities to support high bandwidth, sustained, end-to-end data transmission. Recent trends in technology are showing that although the raw transmission speeds used in networks are increasing rapidly, the rate of advancement of microprocessor technology has slowed down. Therefore, network protocol-processing overheads have risen sharply in comparison with the time spent in packet transmission, resulting in degraded throughput for networked applications. More and more, it is the network end system, instead of the network, that is responsible for degraded performance of network applications. In this paper, the Linux system's packet receive process is studied from NIC to application. We develop a mathematical model to characterize the Linux packet receiving process. Key factors that affect Linux systems network performance are analyzed.

  18. Enhanced reliable transmission control protocol for spatial information networks

    Science.gov (United States)

    Qin, Zhihong; Zhang, Juan; Wang, Junfeng

    2009-12-01

    Satellites channels are generally featured by high bit error rate (BER), long propagation delay, large bandwidth-delay product (BDP) and so on. This tends to make the traditional TCP suffer from serious performance degradation in satellite networks. Therefore, a TCP-compatible reliable transmission protocol (i.e., TCP-AX) for spatial information networks is proposed in this paper. And a bandwidth probing mechanism is designed to distinguish network congestion and link error. Simulation results show that TCP-AX has better performance than some popular enhanced TCP protocols.

  19. Reconfigurable Digital Coherent Receiver for Metro-Access Networks Supporting Mixed Modulation Formats and Bit-rates

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Guerrero Gonzalez, Neil; Arlunno, Valeria

    2013-01-01

    A single, reconfigurable, digital coherent receiver is proposed and experimentally demonstrated for converged wireless and optical fiber transport. The capacity of reconstructing the full transmitted optical field allows for the demodulation of mixed modulation formats and bit-rates. We performed...... experimental validation of different modulation formats, including VCSEL based OOK, baseband QPSK, RoF OFDM and wireless IR-UWB over a 78 km deployed fiber link....

  20. Region of interest video coding for low bit-rate transmission of carotid ultrasound videos over 3G wireless networks.

    Science.gov (United States)

    Tsapatsoulis, Nicolas; Loizou, Christos; Pattichis, Constantinos

    2007-01-01

    Efficient medical video transmission over 3G wireless is of great importance for fast diagnosis and on site medical staff training purposes. In this paper we present a region of interest based ultrasound video compression study which shows that significant reduction of the required, for transmission, bit rate can be achieved without altering the design of existing video codecs. Simple preprocessing of the original videos to define visually and clinically important areas is the only requirement.

  1. Thermal degradation process of polysulfone aramid fiber

    OpenAIRE

    Zhu Fang-Long; Feng Qian-Qian; Xin Qun; Zhou Yu

    2014-01-01

    Polysulfone aramid fiber is one kind of high temperature fibers. In the paper, thermal degradation behavior and kinetics of polysulfone aramid fiber were investigated by thermogravimetric analysis and differential thermogravimetric at different heating rates under nitrogen and air, respectively. The experimental results show that its initial degradation temperature is 375°C in nitrogen and 410°C in air at heating rate of 10 K/min. When temperature went to 8...

  2. Gender differences in the association of perceived social support and social network with self-rated health status among older adults: a population-based study in Brazil

    Science.gov (United States)

    2013-01-01

    Background Older adults are more likely to live alone, because they may have been predeceased by their spouse and friends. Social interaction could also be reduced in this age group due by limited mobility caused by chronic conditions. Therefore, aging is frequently accompanied by reduced social support, which might affect health status. Little is known about the role of gender in the relationship between social support and health in older adults. Hence, the present study tests the hypothesis that gender differences exist in the relationship between perceived social support, social network, and self-rated health (SRH) among older adults. Methods A cross-sectional study using two-stage probabilistic sampling recruited 3,649 individuals aged 60 years and above. Data were collected during the national influenza vaccination campaign in Rio de Janeiro, Brazil, in 2006. Individual interviews collected information on SRH, perceived social support, social network, and other covariates. Multivariate logistic regression analyses using nested models were conducted separately for males and females. Independent variables were organised into six blocks: (1) perceived social support and social network, (2) age group, (3) socioeconomic characteristics, (4) health-related behaviours, (5) use of health care services, (6) functional status measures and somatic health problems. Results Older men who did not participate in group activities were more likely to report poor SRH compared to those who did, (OR = 1.63; 95% CI = 1.16–2.30). Low perceived social support predicted the probability of poor SRH in women (OR = 1.64; 95% CI = 1.16–2.34). Poor SRH was associated with low age, low income, not working, poor functional capacity, and depression in both men and women. More somatic health problems were associated with poor SRH in women. Conclusions The association between social interactions and SRH varies between genders. Low social network involvement is associated with poor SRH in

  3. Gender differences in the association of perceived social support and social network with self-rated health status among older adults: a population-based study in Brazil.

    Science.gov (United States)

    Caetano, Silvana C; Silva, Cosme M F P; Vettore, Mario V

    2013-11-15

    Older adults are more likely to live alone, because they may have been predeceased by their spouse and friends. Social interaction could also be reduced in this age group due by limited mobility caused by chronic conditions. Therefore, aging is frequently accompanied by reduced social support, which might affect health status. Little is known about the role of gender in the relationship between social support and health in older adults. Hence, the present study tests the hypothesis that gender differences exist in the relationship between perceived social support, social network, and self-rated health (SRH) among older adults. A cross-sectional study using two-stage probabilistic sampling recruited 3,649 individuals aged 60 years and above. Data were collected during the national influenza vaccination campaign in Rio de Janeiro, Brazil, in 2006. Individual interviews collected information on SRH, perceived social support, social network, and other covariates. Multivariate logistic regression analyses using nested models were conducted separately for males and females. Independent variables were organised into six blocks: (1) perceived social support and social network, (2) age group, (3) socioeconomic characteristics, (4) health-related behaviours, (5) use of health care services, (6) functional status measures and somatic health problems. Older men who did not participate in group activities were more likely to report poor SRH compared to those who did, (OR = 1.63; 95% CI = 1.16-2.30). Low perceived social support predicted the probability of poor SRH in women (OR = 1.64; 95% CI = 1.16-2.34). Poor SRH was associated with low age, low income, not working, poor functional capacity, and depression in both men and women. More somatic health problems were associated with poor SRH in women. The association between social interactions and SRH varies between genders. Low social network involvement is associated with poor SRH in older men, whereas low perceived social

  4. An FPGA design of generalized low-density parity-check codes for rate-adaptive optical transport networks

    Science.gov (United States)

    Zou, Ding; Djordjevic, Ivan B.

    2016-02-01

    Forward error correction (FEC) is as one of the key technologies enabling the next-generation high-speed fiber optical communications. In this paper, we propose a rate-adaptive scheme using a class of generalized low-density parity-check (GLDPC) codes with a Hamming code as local code. We show that with the proposed unified GLDPC decoder architecture, a variable net coding gains (NCGs) can be achieved with no error floor at BER down to 10-15, making it a viable solution in the next-generation high-speed fiber optical communications.

  5. Mortality Rates Among Substance Use Disorder Participants in Clinical Trials: Pooled Analysis of Twenty-Two Clinical Trials Within the National Drug Abuse Treatment Clinical Trials Network.

    Science.gov (United States)

    Lindblad, Robert; Hu, Lian; Oden, Neal; Wakim, Paul; Rosa, Carmen; VanVeldhuisen, Paul

    2016-11-01

    Most substance use disorders (SUD) treatment clinical trials are too short and small to reliably estimate the incidence of rare events like death. The aim of this study is to estimate the overall mortality rates among a SUD treatment-seeking population by pooling participants from multiple clinical trials conducted through the National Institute on Drug Abuse (NIDA)-sponsored National Drug Abuse Treatment Clinical Trials Network (CTN). Drug and or alcohol users (N=9866) who sought treatment and participated in one of the twenty-two CTN trials. Data were collected through randomized clinical trials in national community treatment programs for SUD. Pooled analysis was performed to assess age- and gender-standardized mortality rate(s) (SM rate(s)), and mortality ratio(s) (SM ratio(s)) of CTN trial participants compared to the U.S. general population. The age- and gender-SM rate among CTN trials participants was 1403 (95% CI: 862-2074) per 100,000 person years (PY) compared to 542 (95% CI: 541-543) per 100,000 PY among the U.S. general population in 2005. By gender, age-adjusted SM ratio for female CTN trial participants was over five times (SM ratio=5.35, 95% CI: 3.31-8.19)), and for male CTN trial participants, it was over three times (SM ratio=3.39, 95% CI: 2.25-4.90) higher than their gender comparable peers in the U.S. general population. Age and gender-standardized mortality rates and ratios among NIDA CTN SUD treatment-seeking clinical trial participants are higher than the age and gender comparable U.S. general population. The overall mortality rates of CTN trial participants are similar to in-treatment mortality reported in large U.S. and non-U.S. cohorts of opioid users. Future analysis with additional CTN trial participants and risk times will improve the stability of estimates, especially within subgroups based on primary substance of abuse. These SUD mortality rates can be used to facilitate safety monitoring within SUD clinical trials. Copyright © 2016

  6. Fitting the elementary rate constants of the P-gp transporter network in the hMDR1-MDCK confluent cell monolayer using a particle swarm algorithm.

    Directory of Open Access Journals (Sweden)

    Deep Agnani

    Full Text Available P-glycoprotein, a human multidrug resistance transporter, has been extensively studied due to its importance to human health and disease. In order to understand transport kinetics via P-gp, confluent cell monolayers overexpressing P-gp are widely used. The purpose of this study is to obtain the mass action elementary rate constants for P-gp's transport and to functionally characterize members of P-gp's network, i.e., other transporters that transport P-gp substrates in hMDR1-MDCKII confluent cell monolayers and are essential to the net substrate flux. Transport of a range of concentrations of amprenavir, loperamide, quinidine and digoxin across the confluent monolayer of cells was measured in both directions, apical to basolateral and basolateral to apical. We developed a global optimization algorithm using the Particle Swarm method that can simultaneously fit all datasets to yield accurate and exhaustive fits of these elementary rate constants. The statistical sensitivity of the fitted values was determined by using 24 identical replicate fits, yielding simple averages and standard deviations for all of the kinetic parameters, including the efflux active P-gp surface density. Digoxin required additional basolateral and apical transporters, while loperamide required just a basolateral tranporter. The data were better fit by assuming bidirectional transporters, rather than active importers, suggesting that they are not MRP or active OATP transporters. The P-gp efflux rate constants for quinidine and digoxin were about 3-fold smaller than reported ATP hydrolysis rate constants from P-gp proteoliposomes. This suggests a roughly 3∶1 stoichiometry between ATP hydrolysis and P-gp transport for these two drugs. The fitted values of the elementary rate constants for these P-gp substrates support the hypotheses that the selective pressures on P-gp are to maintain a broad substrate range and to keep xenobiotics out of the cytosol, but not out of the

  7. Comparison of the historic seismicity and strain-rate pattern from a dense GPS-GNSS network solution in the Italian Peninsula

    Directory of Open Access Journals (Sweden)

    Giuseppe Casula

    2016-09-01

    Full Text Available We present a dense crustal velocity field and corresponding strain-rate pattern computed using Global Positioning System (GPS- Global Navigation Satellite System (GNSS data from several hundred permanent stations in the Italian Peninsula. GPS data analysis is based on the GAMIT/GLOBK 10.6 software, which was developed and maintained mainly by Massachusetts Institute of Technology (MIT, using tools based on the distributed-sessions approach implemented in this package. The GPS data span the period from January 2008 to December 2012 and come from several different permanent GPS networks in Italy. The GLOBK package implemented in the last version of the GAMIT package is used to compute the position time-series and velocities registered in the International Terrestrial Reference Frame (ITRF 2008. The resulting high-density intra-plate velocity field provides indications of the tectonics of the Mediterranean region. A computation of the strain-rate pattern from GPS data is performed and compared with the map of the epicentral locations of historical earthquakes that occurred in the last 1000 years in the Italian territory, showing that, in general, higher crustal deformation rates are active in regions affected by seismicity of greater magnitude.

  8. Verifying the performance of artificial neural network and multiple linear regression in predicting the mean seasonal municipal solid waste generation rate: A case study of Fars province, Iran.

    Science.gov (United States)

    Azadi, Sama; Karimi-Jashni, Ayoub

    2016-02-01

    Predicting the mass of solid waste generation plays an important role in integrated solid waste management plans. In this study, the performance of two predictive models, Artificial Neural Network (ANN) and Multiple Linear Regression (MLR) was verified to predict mean Seasonal Municipal Solid Waste Generation (SMSWG) rate. The accuracy of the proposed models is illustrated through a case study of 20 cities located in Fars Province, Iran. Four performance measures, MAE, MAPE, RMSE and R were used to evaluate the performance of these models. The MLR, as a conventional model, showed poor prediction performance. On the other hand, the results indicated that the ANN model, as a non-linear model, has a higher predictive accuracy when it comes to prediction of the mean SMSWG rate. As a result, in order to develop a more cost-effective strategy for waste management in the future, the ANN model could be used to predict the mean SMSWG rate. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Comparison of the properties of the Spruce wood Picea abies L. (Karst. in various state and rate of degradation by wood-destroying fungus Serpula lacrymans Schröter

    Directory of Open Access Journals (Sweden)

    Jiří Holan

    2008-01-01

    Full Text Available This article deals with the change of mechanical properties of the Spruce wood (Picea abies L. Karst. which was exposed to the attack of the wood-destroying fungus Serpula lacrymans Schröter.An activity of the wood-destroying fungus has negattive effect on the wood and its properties. Growth of the wood-destroying fungus causes degradation of the chemical components of wood. Due to this the mechanical properties are changed and strength of the degraded wood is decreasing with extend of the activity time of the wood-destroying fungus. Together with this Serpula lacrymans Schröter causes the weight-shortage.For tests in this article have been chosen the times of one, two and three months of the wood-destroying fungus attack. And then have been established weight-shortage and determined the strength of the degraded wood with Serpula lacrymans Schröter.

  10. Screening and characterization of petroleum-degrading bacterium ...

    African Journals Online (AJOL)

    ... in 250 ml flask, shaking at 150 r/min and 32°C, petroleum-degrading rate was 75 to 77%. The petroleum-degrading bacterium might be a useful resource for bioremediation of oil-contaminated soils and biotreatment of oil wastewater. Key words: Petroleum-degrading bacterium, screening, Bacillus cereus, bioremediation.

  11. Degradation and toxicity reduction of phenol by ultrasound waves ...

    African Journals Online (AJOL)

    The effects of parameters such as pH, kinetic constants and initial phenol concentration on the sonochemical degradation of phenol and toxicity assay were studied. The experimental results showed that lower pH and lower concentration of phenol favor the phenol degradation. But the rates of phenol degradation under ...

  12. Concentrated Light for Accelerated Photo Degradation of Polymer Materials

    DEFF Research Database (Denmark)

    Madsen, Morten Vesterager; Tromholt, Thomas; Norrman, Kion

    2013-01-01

    Concentrated light is used to perform photochemical degradation of polymer solar cell materials with acceleration factors up to 1200. At constant temperature the photon efficiency in regards to photo degradation is constant for 1–150 suns and oxygen diffusion rates are not a limiting factor....... Accelerated degradation by concentrated light thus allows for rapid and precise evaluations of one sun polymer stabilities....

  13. Diesel degradation and biosurfactant production by Gram-positive ...

    African Journals Online (AJOL)

    All isolates were capable of degrading 70 - 80% of n-paraffin whilst isolates D2, D9, D10 and DJLB possessed better abilities of diesel degradation at 65.4 - 83.12% under the standard conditions. Diesel degradation rates and microbial cell number, increased with an increase in glucose composition. The addition of glucose ...

  14. The General Regression Neural Network Based on the Fruit Fly Optimization Algorithm and the Data Inconsistency Rate for Transmission Line Icing Prediction

    Directory of Open Access Journals (Sweden)

    Dongxiao Niu

    2017-12-01

    Full Text Available Accurate and stable prediction of icing thickness on transmission lines is of great significance for ensuring the safe operation of the power grid. In order to improve the accuracy and stability of icing prediction, an innovative prediction model based on the generalized regression neural network (GRNN and the fruit fly optimization algorithm (FOA is proposed. Firstly, a feature selection method based on the data inconsistency rate (IR is adopted to select the optimal feature, which aims to reduce redundant input vectors. Then, the fruit FOA is utilized for optimization of smoothing factor for the GRNN. Lastly, the icing forecasting method FOA-IR-GRNN is established. Two cases in different locations and different months are selected to validate the proposed model. The results indicate that the new hybrid FOA-IR-GRNN model presents better accuracy, robustness, and generality in icing forecasting.

  15. Polarization-multiplexed rate-adaptive non-binary-quasi-cyclic-LDPC-coded multilevel modulation with coherent detection for optical transport networks.

    Science.gov (United States)

    Arabaci, Murat; Djordjevic, Ivan B; Saunders, Ross; Marcoccia, Roberto M

    2010-02-01

    In order to achieve high-speed transmission over optical transport networks (OTNs) and maximize its throughput, we propose using a rate-adaptive polarization-multiplexed coded multilevel modulation with coherent detection based on component non-binary quasi-cyclic (QC) LDPC codes. Compared to prior-art bit-interleaved LDPC-coded modulation (BI-LDPC-CM) scheme, the proposed non-binary LDPC-coded modulation (NB-LDPC-CM) scheme not only reduces latency due to symbol- instead of bit-level processing but also provides either impressive reduction in computational complexity or striking improvements in coding gain depending on the constellation size. As the paper presents, compared to its prior-art binary counterpart, the proposed NB-LDPC-CM scheme addresses the needs of future OTNs, which are achieving the target BER performance and providing maximum possible throughput both over the entire lifetime of the OTN, better.

  16. A mathematical model of protein degradation by the proteasome

    NARCIS (Netherlands)

    Luciani, F.; Kesmir, C.; Mishto, M.; Or-Guil, 'M.; Boer, R.J. de

    2005-01-01

    The proteasome is the major protease for intracellular protein degradation. The influx rate of protein substrates and the exit rate of the fragments/products are regulated by the size of the axial channels. Opening the channels is known to increase the overall degradation rate and to change the

  17. Characterization and degradation potential of diesel-degrading bacterial strains for application in bioremediation.

    Science.gov (United States)

    Balseiro-Romero, María; Gkorezis, Panagiotis; Kidd, Petra S; Van Hamme, Jonathan; Weyens, Nele; Monterroso, Carmen; Vangronsveld, Jaco

    2017-10-03

    Bioremediation of polluted soils is a promising technique with low environmental impact, which uses soil organisms to degrade soil contaminants. In this study, 19 bacterial strains isolated from a diesel-contaminated soil were screened for their diesel-degrading potential, biosurfactant (BS) production, and biofilm formation abilities, all desirable characteristics when selecting strains for re-inoculation into hydrocarbon-contaminated soils. Diesel-degradation rates were determined in vitro in minimal medium with diesel as the sole carbon source. The capacity to degrade diesel range organics (DROs) of strains SPG23 (Arthobacter sp.) and PF1 (Acinetobacter oleivorans) reached 17-26% of total DROs after 10 days, and 90% for strain GK2 (Acinetobacter calcoaceticus). The amount and rate of alkane degradation decreased significantly with increasing carbon number for strains SPG23 and PF1. Strain GK2, which produced BSs and biofilms, exhibited a greater extent, and faster rate of alkane degradation compared to SPG23 and PF1. Based on the outcomes of degradation experiments, in addition to BS production, biofilm formation capacities, and previous genome characterizations, strain GK2 is a promising candidate for microbial-assisted phytoremediation of diesel-contaminated soils. These results are of particular interest to select suitable strains for bioremediation, not only presenting high diesel-degradation rates, but also other characteristics which could improve rhizosphere colonization.

  18. The Science of Battery Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, John P. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; El Gabaly Marquez, Farid [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; McCarty, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Sugar, Joshua Daniel [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Talin, Alec A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Fenton, Kyle R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Design and Development; Nagasubramanian, Ganesan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Design and Development; Harris, Charles Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanosystems Synthesis/Analysis; Jungjohann, Katherine Leigh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanosystems Synthesis/Analysis; Hayden, Carl C. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Combustion Chemistry Dept.; Kliewer, Christopher Jesse [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Combustion Chemistry Dept.; Hudak, Nicholas S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Research and Development; Leung, Kevin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanostructure Physics; McDaniel, Anthony H. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Hydrogen and Combustion Technology; Tenney, Craig M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Chemical and Biological Systems; Zavadil, Kevin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Materials Lab.

    2015-01-01

    changes little with degradation but the origin of degradation in cathodes is kinetic in nature, i.e. lower rate cycling recovers lost capacity. Finally, our modeling of electrode-electrolyte interfaces revealed that electrolyte degradation may occur by either a single or double electron transfer process depending on thickness of the solid-electrolyte-interphase layer, and this cross-over can be modeled and predicted.

  19. Detection and location of mechanical system degradation by using detector signal noise data

    Energy Technology Data Exchange (ETDEWEB)

    Damiano, B.; Blakeman, E.D.; Phillips, L.D.

    1994-06-01

    This report describes the investigation of a diagnostic method for detecting and locating the source of structural degradation in mechanical systems. The goal of this investigation was to determine whether the diagnostic method would be practically and successfully applied to detect and locate structural changes in a mechanical system. The diagnostic method uses a mathematical model of the mechanical system to define relationships between system parameters, such as spring rates and damping rates, and measurable spectral features, such as natural frequencies and mode shapes. These model-defined relationships are incorporated into a neural network, which is used to relate measured spectral features to system parameters. The diagnosis of the system`s condition is performed by presenting the neural network with measured spectral features and comparing the system parameters estimated by the neural network to previously estimated values. Changes in the estimated system parameters indicate the location and severity of degradation in the mechanical system. The investigation involved applying the method by using computer-simulated data and data collected from a bench-top mechanical system. The effects of neural network training set size and composition on the accuracy of the model parameter estimates were investigated by using computer-simulated data. The measured data were used to demonstrate that the method can be applied to estimate the parameters of a {open_quotes}real{close_quotes} mechanical system. The results show that this diagnostic method can be applied to successfully locate and estimate the magnitude of structural changes in a mechanical system. The average error in the estimated spring rate values of the bench-top mechanical system was approximately 5 to 10%. This degree of accuracy is sufficient to permit the use of this method for detecting and locating structural degradation in mechanical systems.

  20. Effect of exogenous pulmonary surfactants on mortality rate in neonatal respiratory distress syndrome: A network meta-analysis of randomized controlled trials.

    Science.gov (United States)

    Zhang, Liang; Cao, Hong-Yi; Zhao, Shuang; Yuan, Li-Jie; Han, Dan; Jiang, Hong; Wu, Song; Wu, Hong-Min

    2015-10-01

    The utilization of multiple natural and synthetic products in surfactant replacement therapies in treatment of neonatal respiratory distress syndrome (NRDS) prompted us to take a closer looks at these various therapeutic options and their efficacies. The purpose of our study was to evaluate the effects of six exogenous pulmonary surfactants (EPS) (Survanta, Alveofact, Infasurf, Curosurf, Surfaxin and Exosurf) on mortality rate in NRDS by a network meta-analysis. An exhaustive search of electronic databases was performed in PubMed, Ovid, EBSCO, Springerlink, Wiley, Web of Science, Cochrane Library, China National Knowledge Infrastructure, Wanfang and VIP databases (last updated search in October 2014) to retrieve randomized controlled trials (RCTs) relevant to our study topic. Published clinical trials were screened based on the following inclusion criteria: (1) study design: RCTs; (2) interventions: treatment with Survanta, Alveofact, Infasurf, Curosurf, Surfaxin or Exosurf for NRDS; (3) study subject: infants with NRDS confirmed by clinical diagnosis; (4) outcome: the mortality rate of infants with NRDS. Statistical analysis was performed using Stata 12.0 software (Stata Corporation, College Station, TX, USA) and Comprehensive Meta-analysis (CMA 2.0) software. From the 1840 studies initially retrieved through database searches, a total of 17 high quality RCTs were selected for this network meta-analysis. The selected studies included a combined total of 57,223 infants with NRDS treated with various EPS (Survanta, 27,017; Alveofact, 159; Infasurf, 20,377; Curosurf, 20,911; Surfaxin, 646; Exosurf, 1640). Network meta-analysis results showed that the mortality rates in NRDS infants treated with Alveofact, Infasurf, Curosurf, Surfaxin, Exosurf were not significantly different compared to Survanta (Alveofact: OR = 1.163, 95% CI = 0.645-2.099, P = 0.616; Infasurf: OR = 0.985, 95% CI = 0.777-1.248, P = 0.897; Curosurf: OR = 0.789, 95% CI = 0.619-1.007, P = 0

  1. OXIDATIVE DEGRADATION OF 2-CHLOROPHENOL BY PERSULFATE

    Directory of Open Access Journals (Sweden)

    Krzysztof Kuśmierek

    2015-06-01

    Full Text Available The degradation of 2-chlorophenol (2-CP by persulfate was investigated. The kinetics of persulfate oxidation of 2-chlorophenol in aqueous solutions at various pH, oxidant concentration, temperature, Fe2+ and Cu2+ ions content was studied. Maximum of 2-CP degradation occurred at pH 8. The oxidation rate of 2-CP increased with increasing the persulfate molar excess. The degradation process was significantly influenced by temperature – the higher temperature results in a faster degradation of 2-CP. The activation of persulfate by ferrous and copper ions was also studied. Results showed that persulfate is activated more effectively by iron(II than copper(II ions. A comparison of different persulfate activation methods revealed that heat-activation was the most effective. Under optimal conditions, in the presence of ferrous ions at 50 °C, complete degradation of 2-chlorophenol was achieved after about 30 minutes.

  2. Bacterial Degradation of Pesticides

    DEFF Research Database (Denmark)

    Knudsen, Berith Elkær

    . Bioaugmentation i.e. addition of specific degrader organisms, has been suggested as an environmentally friendly and economically competitive strategy for cleaning polluted sites. Several organisms have been isolated, capable of degrading different compounds. However the capacity to degrade the desired compound...... SRS2, Variovorax SRS16 and Arthrobacter globiformis D47. The degradation capacity of each strain individually as well as two- and three-member consortia was studied in a sand column set up. Glass beads were added to the set up to create a dry patch, separating the organisms and the diuron-spiked sand...

  3. Wellbore Integrity Network

    Energy Technology Data Exchange (ETDEWEB)

    Carey, James W. [Los Alamos National Laboratory; Bachu, Stefan [Alberta Innovates

    2012-06-21

    In this presentation, we review the current state of knowledge on wellbore integrity as developed in the IEA Greenhouse Gas Programme's Wellbore Integrity Network. Wells are one of the primary risks to the successful implementation of CO{sub 2} storage programs. Experimental studies show that wellbore materials react with CO{sub 2} (carbonation of cement and corrosion of steel) but the impact on zonal isolation is unclear. Field studies of wells in CO{sub 2}-bearing fields show that CO{sub 2} does migrate external to casing. However, rates and amounts of CO{sub 2} have not been quantified. At the decade time scale, wellbore integrity is driven by construction quality and geomechanical processes. Over longer time-scales (> 100 years), chemical processes (cement degradation and corrosion) become more important, but competing geomechanical processes may preserve wellbore integrity.

  4. Reconfigureable network node

    Science.gov (United States)

    Vanderveen, Keith B [Tracy, CA; Talbot, Edward B [Livermore, CA; Mayer, Laurence E [Davis, CA

    2008-04-08

    Nodes in a network having a plurality of nodes establish communication links with other nodes using available transmission media, as the ability to establish such links becomes available and desirable. The nodes predict when existing communications links will fail, become overloaded or otherwise degrade network effectiveness and act to establish substitute or additional links before the node's ability to communicate with the other nodes on the network is adversely affected. A node stores network topology information and programmed link establishment rules and criteria. The node evaluates characteristics that predict existing links with other nodes becoming unavailable or degraded. The node then determines whether it can form a communication link with a substitute node, in order to maintain connectivity with the network. When changing its communication links, a node broadcasts that information to the network. Other nodes update their stored topology information and consider the updated topology when establishing new communications links for themselves.

  5. Hydrolytic Network Structure Degradation in Multi-Component Polycyanurate Networks

    Science.gov (United States)

    2016-07-28

    ORGANIZATION REPORT NO. Air Force Research Laboratory (AFMC) AFRL/RQRP 10 E. Saturn Blvd. Edwards AFB, CA 93524-7680 9. SPONSORING / MONITORING...Guenthner a. REPORT Unclassified b. ABSTRACT Unclassified c. THIS PAGE Unclassified SAR 19 19b. TELEPHONE NO (include area code ) N/A

  6. Constitutive and ligand-induced TCR degradation

    DEFF Research Database (Denmark)

    von Essen, Marina; Bonefeld, Charlotte Menné; Siersma, Volkert

    2004-01-01

    divergent models for TCR down-regulation and degradation have been suggested. The aims of this study were to determine the rate constants for constitutive and ligand-induced TCR degradation and to determine whether the TCR subunits segregate or are processed as an intact unit during TCR down...... to the lysosomes. Similar results were obtained in studies of primary human Vbeta8+ T cells stimulated with superantigen. Based on these results, the simplest model for TCR internalization, sorting, and degradation is proposed.......Modulation of TCR expression levels is a central event during T cell development and activation, and it probably plays an important role in adjusting T cell responsiveness. Conflicting data have been published on down-regulation and degradation rates of the individual TCR subunits, and several...

  7. Protein Repair and Degradation during Aging

    Directory of Open Access Journals (Sweden)

    Bertrand Friguet

    2002-01-01

    Full Text Available Cellular aging is characterized by a build-up of oxidatively modified proteins. The steady-state level of oxidized proteins depends on the balance between the rate of protein oxidative damage and the rates of protein degradation and repair. Therefore, the accumulation of oxidized protein with age can be due to increased protein damage, decreased oxidized protein degradation and repair, or the combination of both mechanisms. The proteasomal system is the major intracellular proteolytic pathway implicated in the degradation of oxidized protein, and the peptide methionine sulfoxide reductase catalyzes the reduction of methionine sulfoxide (i.e., oxidized methionine to methionine within proteins. A short summary on protein oxidative damage and oxidized protein degradation is given, and evidence for a decline of proteasome function with age is presented. Arguments for the implication of peptide methionine sulfoxide reductase in the age-related accumulation of oxidized protein are also discussed.

  8. Heterogeneous photocatalytic degradation of monochlorobenzene in water.

    Science.gov (United States)

    Huang, Hsin-Hsu; Tseng, Dyi-Hwa; Juang, Lain-Chuen

    2008-08-15

    This investigation evaluated the photocatalytic degradation of monochlorobenzene (MCB) in an aqueous TiO(2) suspension. In accordance with the experimental results, the degradation of MCB was a function of the initial substrate concentration, incident light intensity, and TiO(2) dosage. However, the solution pH had insignificant effect on the degradation efficiency. The heterogeneous photocatalytic degradation of MCB followed the Langmuir-Hinshelwood kinetics. The adsorption coefficient of MCB (K) and the observed degradation rate constant (k) were calculated as 13.4 mM(-1) and 0.0054 mM min(-1), respectively. In addition, a 0.255 dependency of the initial degradation rate on the light intensity revealed the considerable adverse effect of e(-)-h(+) pair recombination. Both mineralization and dechlorination occurred during the photocatalytic degradation of MCB. Under the operating condition of initial MCB concentration of 0.1mM, light intensity of 5.68 microEinsteins(-1), TiO(2) dosage of 1.0 g L(-1), and solution pH of 7, about 93.7% of MCB was mineralized after 240 min of irradiation. Nevertheless, 64.3% of the stoichiometric amount of Cl(-) ions was released into the bulk solution. The simulation results derived from the X-ray photoelectron spectroscopy (XPS) analysis was suggested that the interaction between Cl(-) ions and TiO(2) surface tended to lower the released amount of Cl(-) ions.

  9. Microbial degradation of MTBE in reactors

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2007-01-01

    , toluene, ethylbenzene and xylenes, may reduce the removal rates of MTBE, or prevent its removal in reactors. With mathematical modelling, the long startup time required for some MTBE degrading reactors could be predicted. Long startup times of up to 200 days were due to the low maximum growth rate...... findings were: membrane bioreactors and fluidized bed reactors had the highest volumetric removal rates of all reactors studied, in the order of 1 000 mg/(l d); competition for oxygen, nutrients and occupancy between MTBE degraders and oxidisers of co-contaminants such as, ammonium and the group of benzene...... of the MTBE degraders, in the order of 0.1 d−1 or less, at 25 °C. However, despite this, high volumetric MTBE removal rates were found to be possible after the startup period when the biomass concentration reached a steady state....

  10. A Theoretical Model for Metal Corrosion Degradation

    OpenAIRE

    David V. Svintradze; Pidaparti, Ramana M.

    2010-01-01

    Many aluminum and stainless steel alloys contain thin oxide layers on the metal surface which greatly reduce the corrosion rate. Pitting corrosion, a result of localized breakdown of such films, results in accelerated dissolution of the underlying metal through pits. Many researchers have studied pitting corrosion for several decades and the exact governing equation for corrosion pit degradation has not been obtained. In this study, the governing equation for corrosion degradation due to pitt...

  11. Validation of the 17-item Hamilton Depression Rating Scale definition of response for adults with major depressive disorder using equipercentile linking to Clinical Global Impression scale ratings: analysis of Pharmacogenomic Research Network Antidepressant Medication Pharmacogenomic Study (PGRN-AMPS) data.

    Science.gov (United States)

    Bobo, William V; Angleró, Gabriela C; Jenkins, Gregory; Hall-Flavin, Daniel K; Weinshilboum, Richard; Biernacka, Joanna M

    2016-05-01

    The study aimed to define thresholds of clinically significant change in 17-item Hamilton Depression Rating Scale (HDRS-17) scores using the Clinical Global Impression-Improvement (CGI-I) Scale as a gold standard. We conducted a secondary analysis of individual patient data from the Pharmacogenomic Research Network Antidepressant Medication Pharmacogenomic Study, an 8-week, single-arm clinical trial of citalopram or escitalopram treatment of adults with major depression. We used equipercentile linking to identify levels of absolute and percent change in HDRS-17 scores that equated with scores on the CGI-I at 4 and 8 weeks. Additional analyses equated changes in the HDRS-7 and Bech-6 scale scores with CGI-I scores. A CGI-I score of 2 (much improved) corresponded to an absolute decrease (improvement) in HDRS-17 total score of 11 points and a percent decrease of 50-57%, from baseline values. Similar results were observed for percent change in HDRS-7 and Bech-6 scores. Larger absolute (but not percent) decreases in HDRS-17 scores equated with CGI-I scores of 2 in persons with higher baseline depression severity. Our results support the consensus definition of response based on HDRS-17 scores (>50% decrease from baseline). A similar definition of response may apply to the HDRS-7 and Bech-6. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Use of agro-industrial organic sludge amendment to remediate degraded soil: chemical and eco(geno)toxicological differences between fresh and stabilized sludge and establishment of application rates.

    Science.gov (United States)

    Chiochetta, Claudete G; Cotelle, Sylvie; Masfaraud, Jean-François; Toumi, Hela; Quaranta, Gaetana; Adani, Fabrizio; Radetski, Claudemir M

    2016-02-01

    Soil degraded by coal mining activities can be remediated by amendment with agro-industrial organic sludge. However, the environmental impacts associated with this management practice must be properly addressed. In this context, the objective of this study was to evaluate the eco(geno)toxicity of a fresh and a stabilized sludge before use in a laboratory soil remediation test. Chemical analysis of the complex mixtures (degraded soil, fresh sludge, and stabilized sludge) was carried out, as well as a battery of eco(geno)toxicity tests on microbiological enzymes (fluorescein hydrolysis), earthworms, and higher plants (including Vicia faba genotoxicity test), according to published methodologies. The results of these tests showed that fresh sludge was more toxic than sludge stabilized over 6 months toward earthworms and higher plants (lettuce, corn, and wild cabbage), while phyto(geno)toxicity tests with V. faba indicated the same genotoxicity levels for the two types of sludge. In the soil remediation simulation using different mixtures of degraded soil and stabilized sludge, the proportions of 50:50% (dry weight basis) provided the lowest phyto(geno)toxicity effects and this mixture can be used for the revegetation of the contaminated site.

  13. Intermittent degradation and schizotypy

    Directory of Open Access Journals (Sweden)

    Matthew W. Roché

    2015-06-01

    Full Text Available Intermittent degradation refers to transient detrimental disruptions in task performance. This phenomenon has been repeatedly observed in the performance data of patients with schizophrenia. Whether intermittent degradation is a feature of the liability for schizophrenia (i.e., schizotypy is an open question. Further, the specificity of intermittent degradation to schizotypy has yet to be investigated. To address these questions, 92 undergraduate participants completed a battery of self-report questionnaires assessing schizotypy and psychological state variables (e.g., anxiety, depression, and their reaction times were recorded as they did so. Intermittent degradation was defined as the number of times a subject’s reaction time for questionnaire items met or exceeded three standard deviations from his or her mean reaction time after controlling for each item’s information processing load. Intermittent degradation scores were correlated with questionnaire scores. Our results indicate that intermittent degradation is associated with total scores on measures of positive and disorganized schizotypy, but unrelated to total scores on measures of negative schizotypy and psychological state variables. Intermittent degradation is interpreted as potentially derivative of schizotypy and a candidate endophenotypic marker worthy of continued research.

  14. Degradation kinetics of ptaquiloside in soil and soil solution

    DEFF Research Database (Denmark)

    Ovesen, Rikke Gleerup; Rasmussen, Lars Holm; Hansen, Hans Christian Bruun

    2008-01-01

    Ptaquiloside (PTA) is a carcinogenic norsesquiterpene glycoside produced in bracken (Pteridium aquilinum (L.) Kuhn), a widespread, aggressive weed. Transfer of PTA to soil and soil solution eventually may contaminate groundwater and surface water. Degradation rates of PTA were quantified in soil...... and soil solutions in sandy and clayey soils subjected to high natural PTA loads from bracken stands. Degradation kinetics in moist soil could be fitted with the sum of a fast and a slow first-order reaction; the fast reaction contributed 20 to 50% of the total degradation of PTA. The fast reaction....... Experiments with sterile controls confirmed that nonmicrobial degradation processes constituted more than 90% of the fast degradation and 50% of the slow degradation. The lower nonmicrobial degradation rate observed in the clayey compared with the sandy soil is attributed to a stabilizing effect of PTA...

  15. Thermal Degradation Studies of A Polyurethane Propellant Binder

    Energy Technology Data Exchange (ETDEWEB)

    Assink, R.A.; Celina, M.; Gillen, K.T.; Graham, A.C.; Minier, L.M.

    1999-06-12

    The thermal oxidative aging of a crosslinked hydroxy-terminated polybutadiene (HTPB)/isophorone diisocyanate (IPDI) based polyurethane rubber, used as a polymeric binder in solid propellant grain, was investigated at temperatures from 25 C to 125 C. The changes in tensile elongation, polymer network properties and chain dynamics, mechanical hardening and density were determined with a range of techniques including modulus profiling, solvent swelling, NMR relaxation and O{sub 2} permeability measurements. We critically evaluated the Arrhenius methodology that is commonly used with a linear extrapolation of high temperature aging data using extensive data superposition and highly sensitive oxygen consumption experiments. The effects of other constituents in the propellant formulation on aging were also investigated. We conclude that crosslinking is the dominant process at higher temperatures and that the degradation involves only limited hardening in the bulk of the material. Significant curvature in the Arrhenius diagram of the oxidation rates was observed. This is similar to results for other rubber materials.

  16. Service Degradation in Context Management Frameworks

    DEFF Research Database (Denmark)

    Shawky, Ahmed; Olsen, Rasmus Løvenstein; Pedersen, Jens Myrup

    2011-01-01

    information. The paper considers a developed framework from the ICT project, OPEN, and investigates the impact of applying Differentiated Services (DiffServ) Quality of Services (QoS). The paper finally provides insight in how the insight gained can be utilized to ensure reliable remote accessed context......Context aware network services are a new and inter-esting way to enhance network users experience. A context aware application/service enhances network performance in relation to dynamic context information, e.g. mobility, location and device information as it senses and reacts to environment...... changes. The reliability of the information accessed is a key factor in achieving reliable context aware application. This paper will review the service degradation in Context Management Frameworks (CMF) and the effect of high network utilization, with particular focus on the reliability of the accessed...

  17. Degradation of implant materials

    CERN Document Server

    Eliaz, Noam

    2012-01-01

    This book surveys the degradation of implant materials, reviewing in detail such failure mechanisms as corrosion, fatigue and wear, along with monitoring techniques. Surveys common implant biomaterials, as well as procedures for implant retrieval and analysis.

  18. Bacterial Degradation of Pesticides

    DEFF Research Database (Denmark)

    Knudsen, Berith Elkær

    This PhD project was carried out as part of the Microbial Remediation of Contaminated Soil and Water Resources (MIRESOWA) project, funded by the Danish Council for Strategic Research (grant number 2104-08-0012). The environment is contaminated with various xenobiotic compounds e.g. pesticides....... Bioaugmentation i.e. addition of specific degrader organisms, has been suggested as an environmentally friendly and economically competitive strategy for cleaning polluted sites. Several organisms have been isolated, capable of degrading different compounds. However the capacity to degrade the desired compound...... is just one requirement for successful bioaugmentation. There are several challenges that need to be overcome in order for bioaugmentation to be sufficiently efficient. The purpose of this PhD project was to study the degradative abilities of different bacteria, and, in collaboration with a fellow Ph...

  19. Exploring the critical dependence of adsorption of various dyes on the degradation rate using Ln{sup 3+}-TiO{sub 2} surface under UV/solar light

    Energy Technology Data Exchange (ETDEWEB)

    Devi, L. Gomathi, E-mail: gomatidevi_naik@yahoo.co.in [Department of Post Graduate Studies in Chemistry, Central College City Campus, Dr. Ambedkar Street, Bangalore University, Bangalore 560001 (India); Kumar, S. Girish [Department of Post Graduate Studies in Chemistry, Central College City Campus, Dr. Ambedkar Street, Bangalore University, Bangalore 560001 (India)

    2012-11-15

    Graphical abstract: The surface reactive acidic sites enhances on doping with rare earth ions which facilitates efficient adsorption of the dye molecules on the catalyst surface. In addition, the nature of the dopant, its concentration and electronic configuration additionally contributes to the overall efficiency. Highlights: Black-Right-Pointing-Pointer The degradation of structurally different anionic dyes under different pH conditions is reported. Black-Right-Pointing-Pointer Pre adsorption of pollutant on catalyst surface is vital for efficient photocatalysis. Black-Right-Pointing-Pointer Adsorption of dye on the catalyst surface depends on the substituent's attached to it. Black-Right-Pointing-Pointer The dopant with half filled electronic configuration served as shallow traps for charge carriers. - Abstract: The degradation of structurally different anionic dyes like Alizarin Red S (ARS) Amaranth (AR), Brilliant Yellow (BY), Congo Red (CR), Fast Red (FR), Methyl Orange (MO), and Methyl Red (MR) were carried out using Ln{sup 3+} (Ln{sup 3+} = La{sup 3+}, Ce{sup 3+} and Gd{sup 3+}) doped TiO{sub 2} at different pH conditions under UV/solar light. All the anionic dyes underwent rapid degradation at acidic pH, while resisted at alkaline conditions due to the adsorptive tendency of these dyes on the catalyst surface at different pH conditions. Gd{sup 3+} (0.15 mol%)-TiO{sub 2} exhibited better activity compared to other photocatalyst ascribed to half filled electronic configuration of Gd{sup 3+} ions. It is proposed that Ln{sup 3+} serves only as charge carrier traps under UV light, while it also act as visible light sensitizers under solar light. Irrespective of the catalyst and excitation source, the dye degradation followed the order: AR > FR > MO > MR > ARS > BY > CR. The results suggest that pre-adsorption of the pollutant is vital for efficient photocatalysis which is dependent on the nature of the substituent's group attached to the dye molecule.

  20. Anthocyanins degradation during storage of Hibiscus sabdariffa extract and evolution of its degradation products.

    Science.gov (United States)

    Sinela, André; Rawat, Nadirah; Mertz, Christian; Achir, Nawel; Fulcrand, Hélène; Dornier, Manuel

    2017-01-01

    Degradation parameters of two main anthocyanins from roselle extract (Hibiscus sabdariffa L.) stored at different temperatures (4-37°C) over 60days were determined. Anthocyanins and some of their degradation products were monitored and quantified using HPLC-MS and DAD. Degradation of anthocyanins followed first-order kinetics and reaction rate constants (k values), which were obtained by non-linear regression, showed that the degradation rate of delphinidin 3-O-sambubioside was higher than that of cyanidin 3-O-sambubioside with k values of 9.2·10(-7)s(-1) and 8.4·10(-7)s(-1) at 37°C respectively. The temperature dependence of the rate of anthocyanin degradation was modeled by the Arrhenius equation. Degradation of delphinidin 3-O-sambubioside (Ea=90kJmol(-1)) tended to be significantly more sensitive to an increase in temperature than cyanidin 3-O-sambubioside (Ea=80kJmol(-1)). Degradation of these anthocyanins formed scission products (gallic and protocatechuic acids respectively) and was accompanied by an increase in polymeric color index. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Thraustochytrid protists degrade hydrocarbons

    Digital Repository Service at National Institute of Oceanography (India)

    Raikar, M.T.; Raghukumar, S.; Vani, V.; David, J.J.; Chandramohan, D.

    that thraustochytrids have the capability to utilize a wide range of organic nitrogen and carbon compounds for their nutrition. However, the capability of these protists to degrade hydrocarbons has not been examined so far. Hydrocarbons occur in seawater either... chromatography. (1) Gravimetry: Tarballs were extracted from experimental flasks with 10 ml of carbon tetrachloride, the extract transferred to pre- weighed Petri dish and the solvent allowed to RAIKAR et al.: THRAUSTOCHYTRID PROTISTS DEGRADE HYDROCARBONS...

  2. Colourful parrot feathers resist bacterial degradation

    Science.gov (United States)

    Burtt, Edward H.; Schroeder, Max R.; Smith, Lauren A.; Sroka, Jenna E.; McGraw, Kevin J.

    2011-01-01

    The brilliant red, orange and yellow colours of parrot feathers are the product of psittacofulvins, which are synthetic pigments known only from parrots. Recent evidence suggests that some pigments in bird feathers function not just as colour generators, but also preserve plumage integrity by increasing the resistance of feather keratin to bacterial degradation. We exposed a variety of colourful parrot feathers to feather-degrading Bacillus licheniformis and found that feathers with red psittacofulvins degraded at about the same rate as those with melanin and more slowly than white feathers, which lack pigments. Blue feathers, in which colour is based on the microstructural arrangement of keratin, air and melanin granules, and green feathers, which combine structural blue with yellow psittacofulvins, degraded at a rate similar to that of red and black feathers. These differences in resistance to bacterial degradation of differently coloured feathers suggest that colour patterns within the Psittaciformes may have evolved to resist bacterial degradation, in addition to their role in communication and camouflage. PMID:20926430

  3. A non-equilibrium thermodynamic model for tumor extracellular matrix with enzymatic degradation

    Science.gov (United States)

    Xue, Shi-Lei; Li, Bo; Feng, Xi-Qiao; Gao, Huajian

    2017-07-01

    The extracellular matrix (ECM) of a solid tumor not only affords scaffolding to support tumor architecture and integrity but also plays an essential role in tumor growth, invasion, metastasis, and therapeutics. In this paper, a non-equilibrium thermodynamic theory is established to study the chemo-mechanical behaviors of tumor ECM, which is modeled as a poroelastic polyelectrolyte consisting of a collagen network and proteoglycans. By using the principle of maximum energy dissipation rate, we deduce a set of governing equations for drug transport and mechanosensitive enzymatic degradation in ECM. The results reveal that osmosis is primarily responsible for the compression resistance of ECM. It is suggested that a well-designed ECM degradation can effectively modify the tumor microenvironment for improved efficiency of cancer therapy. The theoretical predictions show a good agreement with relevant experimental observations. This study aimed to deepen our understanding of tumor ECM may be conducive to novel anticancer strategies.

  4. Radiation-induced degradation of methyl orange in aqueous solutions.

    Science.gov (United States)

    Chen, You-Peng; Liu, Shao-Yang; Yu, Han-Qing; Yin, Hao; Li, Qian-Rong

    2008-06-01

    Degradation of methyl orange under gamma-irradiation was investigated. The reactions followed pseudo first-order kinetics. Apparent degradation rate constant, estimated through linear regression analysis, increased with an increase of dose rate and a decrease of initial methyl orange concentration. Degradation of methyl orange was significantly accelerated under oxidative condition, but was slightly enhanced under reductive condition. However, the result of decoloration was better under reductive condition than oxidative one. An analysis on the intermediates using Fourier transform infrared and gas chromatography/mass spectrometry demonstrates that the radiolytic degradation of methyl orange was processed with different C-N cleavages under oxidative and reductive conditions.

  5. Efficacy and completion rates of rifapentine and isoniazid (3HP) compared to other treatment regimens for latent tuberculosis infection: a systematic review with network meta-analyses.

    Science.gov (United States)

    Pease, Christopher; Hutton, Brian; Yazdi, Fatemeh; Wolfe, Dianna; Hamel, Candyce; Quach, Pauline; Skidmore, Becky; Moher, David; Alvarez, Gonzalo G

    2017-04-11

    We conducted a systematic review and network meta-analysis (NMA) to examine the efficacy and completion rates of treatments for latent tuberculosis infection (LTBI). While a previous review found newer, short-duration regimens to be effective, several included studies did not confirm LTBI, and analyses did not account for variable follow-up or assess completion. We searched MEDLINE, Embase, CENTRAL, PubMed, and additional sources to identify RCTs in patients with confirmed LTBI that involved a regimen of interest and reported on efficacy or completion. Regimens of interest included isoniazid (INH) with rifapentine once weekly for 12 weeks (INH/RPT-3), 6 and 9 months of daily INH (INH-6; INH-9), 3-4 months daily INH plus rifampicin (INH/RFMP 3-4), and 4 months daily rifampicin alone (RFMP-4). NMAs were performed to compare regimens for both endpoints. Sixteen RCTs (n = 44,149) and 14 RCTs (n = 44,128) were included in analyses of efficacy and completion. Studies were published between 1968 and 2015, and there was diversity in patient age and comorbidities. All regimens of interest except INH-9 showed significant benefits in preventing active TB compared to placebo. Comparisons between active regimens did not reveal significant differences. While definitions of regimen completion varied across studies, regimens of 3-4 months were associated with a greater likelihood of adequate completion. Most of the active regimens showed an ability to reduce the risk of active TB relative to no treatment, however important differences between active regimens were not found. Shorter rifamycin-based regimens may offer comparable benefits to longer INH regimens. Regimens of 3-4 months duration are more likely to be completed than longer regimens.

  6. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. Kicker

    2004-09-16

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal

  7. Hydrocarbon degradation, plant colonization and gene expression of alkane degradation genes by endophytic Enterobacter ludwigii strains

    Energy Technology Data Exchange (ETDEWEB)

    Yousaf, Sohail [AIT Austrian Institute of Technology GmbH, Bioresources Unit, A-2444 Seibersdorf (Austria); Afzal, Muhammad [AIT Austrian Institute of Technology GmbH, Bioresources Unit, A-2444 Seibersdorf (Austria); National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad (Pakistan); Reichenauer, Thomas G. [AIT Austrian Institute of Technology GmbH, Environmental Resources and Technologies Unit, A-2444 Seibersdorf (Austria); Brady, Carrie L. [Forestry and Agricultural Biotechnology Institute, Department of Microbiology and Plant Pathology, University of Pretoria, Pretoria (South Africa); Sessitsch, Angela, E-mail: angela.sessitsch@ait.ac.at [AIT Austrian Institute of Technology GmbH, Bioresources Unit, A-2444 Seibersdorf (Austria)

    2011-10-15

    The genus Enterobacter comprises a range of beneficial plant-associated bacteria showing plant growth promotion. Enterobacter ludwigii belongs to the Enterobacter cloacae complex and has been reported to include human pathogens but also plant-associated strains with plant beneficial capacities. To assess the role of Enterobacter endophytes in hydrocarbon degradation, plant colonization, abundance and expression of CYP153 genes in different plant compartments, three plant species (Italian ryegrass, birdsfoot trefoil and alfalfa) were grown in sterile soil spiked with 1% diesel and inoculated with three endophytic E. ludwigii strains. Results showed that all strains were capable of hydrocarbon degradation and efficiently colonized the rhizosphere and plant interior. Two strains, ISI10-3 and BRI10-9, showed highest degradation rates of diesel fuel up to 68% and performed best in combination with Italian ryegrass and alfalfa. All strains expressed the CYP153 gene in all plant compartments, indicating an active role in degradation of diesel in association with plants. - Highlights: > E. ludwigii strains efficiently colonized plants in a non-sterile soil environment. > E. ludwigii strains efficiently expressed alkane degradation genes in plants. > E. ludwigii efficiently degraded alkane contaminations and promoted plant growth. > E. ludwigii interacted more effectively with Italian ryegrass than with other plants. > Degradation activity varied with plant and microbial genotype as well as with time. - Enterobacter ludwigii strains belonging to the E. cloacae complex are able to efficiently degrade alkanes when associated with plants and to promote plant growth.

  8. Social capital and core network ties: a validation study of individual-level social capital measures and their association with extra- and intra-neighborhood ties, and self-rated health.

    Science.gov (United States)

    Moore, Spencer; Bockenholt, Ulf; Daniel, Mark; Frohlich, Katherine; Kestens, Yan; Richard, Lucie

    2011-03-01

    Research on social capital and health has assumed that measures of trust, participation, and perceived cohesion capture aspects of people's neighborhood social connections. This study uses data on the personal networks of 2707 Montreal adults in 300 different neighborhoods to examine the association of socio-demographic and social capital variables with the likelihood of having core ties, core neighborhood ties, and high self-rated health (SRH). Persons with higher household income were more likely to have core ties, but less likely to have core neighborhood ties. Persons with greater diversity in extra-neighborhood network capital were more likely to have core ties, and persons with greater diversity in intra-neighborhood network capital were more likely to have core neighborhood ties. Generalized trust, perceived neighborhood cohesion, and extra-neighborhood network diversity were shown associated with high SRH. Conventional measures of social capital may not capture network mechanisms. Findings suggest a critical appraisal of the mechanisms linking social capital and health, and the further delineation of network and psychosocial mechanisms in understanding these links. Copyright © 2010 Elsevier Ltd. All rights reserved.

  9. Bioprinting three-dimensional cell-laden tissue constructs with controllable degradation.

    Science.gov (United States)

    Wu, Zhengjie; Su, Xin; Xu, Yuanyuan; Kong, Bin; Sun, Wei; Mi, Shengli

    2016-04-19

    Alginate hydrogel is a popular biologically inert material that is widely used in 3D bioprinting, especially in extrusion-based printing. However, the printed cells in this hydrogel could not degrade the surrounding alginate gel matrix, causing them to remain in a poorly proliferating and non-differentiating state. Here, we report a novel study of the 3D printing of human corneal epithelial cells (HCECs)/collagen/gelatin/alginate hydrogel incubated with a medium containing sodium citrate to obtain degradation-controllable cell-laden tissue constructs. The 3D-printed hydrogel network with interconnected channels and a macroporous structure was stable and achieved high cell viability (over 90%). By altering the mole ratio of sodium citrate/sodium alginate, the degradation time of the bioprinting constructs can be controlled. Cell proliferation and specific marker protein expression results also revealed that with the help of sodium citrate degradation, the printed HCECs showed a higher proliferation rate and greater cytokeratin 3(CK3) expression, indicating that this newly developed method may help to improve the alginate bioink system for the application of 3D bioprinting in tissue engineering.

  10. Thermal degradation process of polysulfone aramid fiber

    Directory of Open Access Journals (Sweden)

    Zhu Fang-Long

    2014-01-01

    Full Text Available Polysulfone aramid fiber is one kind of high temperature fibers. In the paper, thermal degradation behavior and kinetics of polysulfone aramid fiber were investigated by thermogravimetric analysis and differential thermogravimetric at different heating rates under nitrogen and air, respectively. The experimental results show that its initial degradation temperature is 375°C in nitrogen and 410°C in air at heating rate of 10 K/min. When temperature went to 800°C, the fiber loses all mass in air. The mass losses in the stage showed that degradation of polysulfone aramid occurs in two-step process as could be concluded by the presence of two distinct exothermic peaks in differential thermogravimetric curves.

  11. Motor degradation prediction methods

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, J.R.; Kelly, J.F.; Delzingaro, M.J.

    1996-12-01

    Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor`s duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures.

  12. P-nitrophenol degradation by activated sludge attached on nonwovens.

    Science.gov (United States)

    Bhatti, Zafar Iqbal; Toda, Haruko; Furukawa, Kenji

    2002-03-01

    p-Nitrophenol (PNP) is a toxic compound that enters the environment during manufacturing and processing of a variety of industrial products. This study demonstrates the use of inexpensive and durable nonwovens as a biomass retainer for the biological degradation of p-nitrophenol. An essential aspect of p-nitrophenol degradation was the cultivation of p-nitrophenol degrading biomass prior to its attachment on the nonwovens. Results of continuous flow experiments demonstrated that using the nonwovens could attain consistent high-rate p-nitrophenol degradation. 500 mg-PNP/L was completely degraded at a hydraulic retention time of 11 h. Specific and volumetric p-nitrophenol loading rates were determined to be 165 mg-PNP/g-MLSS/d and 1.6 g-PNP/L/d, respectively. Nitrite released from p-nitrophenol breakdown was not completely nitrified to nitrate. Characteristics of p-nitrophenol degrading sludge were also investigated.

  13. Antifoam degradation testing

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Zamecnik, J. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Newell, D. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Williams, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL)

    2015-08-20

    This report describes the results of testing to quantify the degradation products resulting from the dilution and storage of Antifoam 747. Antifoam degradation is of concern to the Defense Waste Processing Facility (DWPF) due to flammable decomposition products in the vapor phase of the Chemical Process Cell vessels, as well as the collection of flammable and organic species in the offgas condensate. The discovery that hexamethyldisiloxane is formed from the antifoam decomposition was the basis for a Potential Inadequacy in the Safety Analysis declaration by the DWPF.

  14. Utilizing Joint Routing and Capacity Assignment Algorithms to Achieve Inter- and Intra-Group Delay Fairness in Multi-Rate Multicast Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yean-Fu Wen

    2013-03-01

    Full Text Available Recent advance in wireless sensor network (WSN applications such as the Internet of Things (IoT have attracted a lot of attention. Sensor nodes have to monitor and cooperatively pass their data, such as temperature, sound, pressure, etc. through the network under constrained physical or environmental conditions. The Quality of Service (QoS is very sensitive to network delays. When resources are constrained and when the number of receivers increases rapidly, how the sensor network can provide good QoS (measured as end-to-end delay becomes a very critical problem. In this paper; a solution to the wireless sensor network multicasting problem is proposed in which a mathematical model that provides services to accommodate delay fairness for each subscriber is constructed. Granting equal consideration to both network link capacity assignment and routing strategies for each multicast group guarantees the intra-group and inter-group delay fairness of end-to-end delay. Minimizing delay and achieving fairness is ultimately achieved through the Lagrangean Relaxation method and Subgradient Optimization Technique. Test results indicate that the new system runs with greater effectiveness and efficiency.

  15. Utilizing joint routing and capacity assignment algorithms to achieve inter- and intra-group delay fairness in multi-rate multicast wireless sensor networks.

    Science.gov (United States)

    Lin, Frank Yeong-Sung; Hsiao, Chiu-Han; Lin, Leo Shih-Chang; Wen, Yean-Fu

    2013-03-14

    Recent advance in wireless sensor network (WSN) applications such as the Internet of Things (IoT) have attracted a lot of attention. Sensor nodes have to monitor and cooperatively pass their data, such as temperature, sound, pressure, etc. through the network under constrained physical or environmental conditions. The Quality of Service (QoS) is very sensitive to network delays. When resources are constrained and when the number of receivers increases rapidly, how the sensor network can provide good QoS (measured as end-to-end delay) becomes a very critical problem. In this paper; a solution to the wireless sensor network multicasting problem is proposed in which a mathematical model that provides services to accommodate delay fairness for each subscriber is constructed. Granting equal consideration to both network link capacity assignment and routing strategies for each multicast group guarantees the intra-group and inter-group delay fairness of end-to-end delay. Minimizing delay and achieving fairness is ultimately achieved through the Lagrangean Relaxation method and Subgradient Optimization Technique. Test results indicate that the new system runs with greater effectiveness and efficiency.

  16. Utilizing Joint Routing and Capacity Assignment Algorithms to Achieve Inter- and Intra-Group Delay Fairness in Multi-Rate Multicast Wireless Sensor Networks

    Science.gov (United States)

    Lin, Frank Yeong-Sung; Hsiao, Chiu-Han; Lin, Leo Shih-Chang; Wen, Yean-Fu

    2013-01-01

    Recent advance in wireless sensor network (WSN) applications such as the Internet of Things (IoT) have attracted a lot of attention. Sensor nodes have to monitor and cooperatively pass their data, such as temperature, sound, pressure, etc. through the network under constrained physical or environmental conditions. The Quality of Service (QoS) is very sensitive to network delays. When resources are constrained and when the number of receivers increases rapidly, how the sensor network can provide good QoS (measured as end-to-end delay) becomes a very critical problem. In this paper; a solution to the wireless sensor network multicasting problem is proposed in which a mathematical model that provides services to accommodate delay fairness for each subscriber is constructed. Granting equal consideration to both network link capacity assignment and routing strategies for each multicast group guarantees the intra-group and inter-group delay fairness of end-to-end delay. Minimizing delay and achieving fairness is ultimately achieved through the Lagrangean Relaxation method and Subgradient Optimization Technique. Test results indicate that the new system runs with greater effectiveness and efficiency. PMID:23493123

  17. Roles of protein ubiquitination and degradation kinetics in biological oscillations.

    Directory of Open Access Journals (Sweden)

    Lida Xu

    Full Text Available Protein ubiquitination and degradation play important roles in many biological functions and are associated with many human diseases. It is well known that for biochemical oscillations to occur, proper degradation rates of the participating proteins are needed. In most mathematical models of biochemical reactions, linear degradation kinetics has been used. However, the degradation kinetics in real systems may be nonlinear, and how nonlinear degradation kinetics affects biological oscillations are not well understood. In this study, we first develop a biochemical reaction model of protein ubiquitination and degradation and calculate the degradation rate against the concentration of the free substrate. We show that the protein degradation kinetics mainly follows the Michaelis-Menten formulation with a time delay caused by ubiquitination and deubiquitination. We then study analytically how the Michaelis-Menten degradation kinetics affects the instabilities that lead to oscillations using three generic oscillation models: 1 a positive feedback mediated oscillator; 2 a positive-plus-negative feedback mediated oscillator; and 3 a negative feedback mediated oscillator. In all three cases, nonlinear degradation kinetics promotes oscillations, especially for the negative feedback mediated oscillator, resulting in much larger oscillation amplitudes and slower frequencies than those observed with linear kinetics. However, the time delay due to protein ubiquitination and deubiquitination generally suppresses oscillations, reducing the amplitude and increasing the frequency of the oscillations. These theoretical analyses provide mechanistic insights into the effects of specific proteins in the ubiquitination-proteasome system on biological oscillations.

  18. Lactose contaminant as steroid degradation enhancer

    NARCIS (Netherlands)

    Nieuwmeyer, Florentine; Maarschalk, Kees van der Voort; Vromans, Herman

    2008-01-01

    Purpose. By pharmaceutical processes and in the presence of solid excipients physical-chemical changes are known to occur, leading to increased rate of chemical degradation. The purpose of this work was to determine the critical aspects in the stability of a steroid in the presence of a commonly

  19. VISIBLE LIGHT INDUCED PHOTOCATALYTIC DEGRADATION OF ...

    African Journals Online (AJOL)

    a

    ABSTRACT. Photocatalytic degradation of eosin and erythrosin-B (xanthene dyes) has been carried out using anthracene semiconductor immobilized on polyethylene films. Effect of various parameters like pH, concentration of dyes, amount of semiconductor and light intensity have been studied on the rate of reaction.

  20. Connecting Indicators with land degradation and desertification

    Science.gov (United States)

    Kosmas, C.

    2012-04-01

    A series of 72 selected candidate indicators corresponding to the physical environment, social, economic, and land management characteristics were defined in 1672 field sites located in 17 study sites in the Mediterranean and eastern Europe, Latin America, Africa, and Asia. The selected indicators refer to specific farm characteristics such as family status, land tenure, present and previous types of land use, period of existing type of land use, soil depth, slope gradient, tillage operations, tillage depth and direction, etc., as well as to regional characteristics such as annual rainfall, rain seasonality, water availability, water quality and quantity, rate of land abandonment, rate of burned area, etc. Based on existing geo-referenced database, classes have been designated for each indicator and presented in a tabulated form. Weighing indices have been assigned to each class based on existing research or empirically assessing the importance to land degradation and desertification. Various processes or causes related to land degradation and desertification important for the study sites have been studied and the most relevant indicators have been defined. Questionnaires for each process or cause have been prepared and data were collected at field site level in collaboration with land users. The obtained data were statistically analyzed to identify the most important indicators related to each process or cause affecting land degradation and desertification. The analyses have shown that indicators may be widely, even globally, used for assessing the various land degradation and desertification processes or causes at field level. Of course, some indicators related to agriculture, social, and institutional characteristics in some cases show trends that are opposite to what happens in other study sites. These trends can be explained by further investigation including other indicators or processes affecting land degradation and desertification that it was not possible

  1. Mineral induced mechanochemical degradation: the imazaquin case.

    Science.gov (United States)

    Nasser, Ahmed; Buchanovsky, Nadia; Gerstl, Zev; Mingelgrin, Uri

    2009-03-01

    The potential role of mechanochemical processes in enhancing degradation of imazaquin by soil components is demonstrated. The investigated components include montmorillonite saturated with Na(+), Ca(2+), Cu(2+)and Al(3+), Agsorb (a commercial clay mix), birnessite and hematite. The mechanical force applied was manual grinding of mixtures of imazaquin and the minerals, using mortar and pestle. The degradation rates of imazaquin in these mixtures were examined as a function of the following parameters: time of grinding, herbicide load (3.9, 8.9, 16.7 and 26.6 mg imazaquin per g mineral), temperature (10, 25, 40 and 70 degrees C), acidic/basic conditions, and dry or wet grinding. Dry grinding of imazaquin for 5 min with Al-montmorillonite or with hematite resulted in 56% and 71% degradation of the imazaquin, respectively. Wet grinding slightly reduced the degradation rate with hematite and entirely cancelled the enhancing effect of grinding with Al-montmorillonite. Wet grinding in the presence of the transition metals: Ni(2+), Cu(2+), Fe(3+) added as chlorides was carried out. Addition of Cu(2+) to Na-montmorillonite loaded with imazaquin was the most effective treatment in degrading imazaquin (more than 90% of the imazaquin degraded after 5 min of grinding). In this treatment, Cu-montmorillonite formation during the grinding process was confirmed by XRD and accordingly, grinding with Cu-montmorillonite gave similar degradation values. LC-MS analysis revealed that the mechanochemical transformation of imazaquin resulted in the formation of a dimer and several breakdown products. The reported results demonstrate once again that mechanochemical procedures offer a remediation avenue applicable to soils polluted with organic contaminants.

  2. Investigation of the degradation of LSM-YSZ SOFC cathode by electrochemical impedance spectroscopy

    DEFF Research Database (Denmark)

    Torres da Silva, Iris Maura

    , it was discovered that impurities in air cause significant degradation of the cathode. Humidity was found to increase the degradation rate, but other impurities might also be present and increasing degradation. Then the anode supported Ni-YSZ/YSZ/LSM-YSZ single cells were prepared and tested. It was found...... and degradation data can only be obtained on single cells as symmetrical cells can only be tested at OCV. For single cells degradation caused by impurities from air was also observed....

  3. Physiological and phylogenetic characterization of a stable benzene-degrading, chlorate-reducing microbial community

    NARCIS (Netherlands)

    Weelink, S.A.B.; Tan, N.C.G.; Broeke, H. ten; Doesburg, W. van; Langenhoff, A.A.M.; Gerritse, J.; Stams, A.J.M.

    2007-01-01

    A stable anoxic enrichment culture was obtained that degraded benzene with chlorate as an electron acceptor. The benzene degradation rate was 1.65 mM benzene per day, which is similar to reported aerobic benzene degradation rates but 20-1650 times higher than reported for anaerobic benzene

  4. Novel Method for Measuring the Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters Based on Artificial Neural Networks and Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Zhijian Liu

    2015-08-01

    Full Text Available The determinations of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, the direct determination requires complex detection devices and a series of standard experiments, which also wastes too much time and manpower. To address this problem, we propose machine learning models including artificial neural networks (ANNs and support vector machines (SVM to predict the heat collection rate and heat loss coefficient without a direct determination. Parameters that can be easily obtained by “portable test instruments” were set as independent variables, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, final temperature and angle between tubes and ground, while the heat collection rate and heat loss coefficient determined by the detection device were set as dependent variables respectively. Nine hundred fifteen samples from in-service water-in-glass evacuated tube solar water heaters were used for training and testing the models. Results show that the multilayer feed-forward neural network (MLFN with 3 nodes is the best model for the prediction of heat collection rate and the general regression neural network (GRNN is the best model for the prediction of heat loss coefficient due to their low root mean square (RMS errors, short training times, and high prediction accuracies (under the tolerances of 30%, 20%, and 10%, respectively.

  5. Endocytic collagen degradation

    DEFF Research Database (Denmark)

    Madsen, Daniel H.; Jürgensen, Henrik J.; Ingvarsen, Signe Ziir

    2012-01-01

    it crucially important to understand both the collagen synthesis and turnover mechanisms in this condition. Here we show that the endocytic collagen receptor, uPARAP/Endo180, is a major determinant in governing the balance between collagen deposition and degradation. Cirrhotic human livers displayed a marked...

  6. Degradation of fluorotelomer alcohols

    DEFF Research Database (Denmark)

    Ellis, David A; Martin, Jonathan W; De Silva, Amila O

    2004-01-01

    . The significance of the gas-phase peroxy radical cross reactions that produce PFCAs has not been recognized previously. Such reactions are expected to occur during the atmospheric degradation of all polyfluorinated materials, necessitating a reexamination of the environmental fate and impact of this important...... class of industrial chemicals....

  7. Adaptive Rate-Scheduling with Reactive Delay Control for Next Generation CDMA Wireless Mobile Systems

    Directory of Open Access Journals (Sweden)

    Yu Oliver

    2006-01-01

    Full Text Available To minimize QoS degradations during nonstationary packet loadings, predictive rate schedulers adapt the operation according to anticipated packet arrival rates deduced via specified estimation algorithm. Existing predictive rate schedulers are developed under the assumption of perfect estimation, which may not be possible in future CDMA-based cellular networks characterized with highly nonstationary and bursty traffic. Additional shortcoming of existing rate schedulers is the coupling of delay and bandwidth, that is, close interdependence of delay and bandwidth (rate, whereby controlling one is accomplished solely by changing the other. In order to mitigate for the arrival rate estimation errors and delay-bandwidth coupling, this paper presents the feedback-enhanced target-tracking weighted fair queuing (FT-WFQ rate scheduler. It is an adaptive rate scheduler over multiclass CDMA systems with predictive adaptation control to adapt to nonstationary loadings; and feedback-enhanced reactive adaptation control to counteract arrival rate estimation errors. When the predictive adaptation control is not able to maintain long-term delay targets, feedback information will trigger reactive adaptation control. The objective of FT-WFQ scheduler is to minimize deviations from delay targets subject to maximum throughput utilization. Analytical and simulation results indicate that FT-WFQ is able to substantially reduce degradations caused by arrival rate estimation errors and to minimize delay degradations during nonstationary loading conditions.

  8. Investigating the Mechanical Properties and Degradability of Bioplastics Made from Wheat Straw Cellulose and Date Palm Fiber

    Directory of Open Access Journals (Sweden)

    H Omrani Fard

    2014-04-01

    Full Text Available During the past two decades, the use of bioplastics as an alternative to regular plastics has received much attention in many different industries. The mechanical and degradable properties of bioplastic are important for their utilization. In this research cellulose of wheat straw and glycerol were mixed by different weight ratios and then reinforced by using date palm fibers. To prepare the bioplastic plates, the materials were poured in molds and pressed by means of a hydraulic press and simultaneously heating of the molds. The experiments were performed based on a 3×3 factorial design with three levels: 50%, 60% and 70% of wheat cellulose and three types of reinforcement methods, namely: no-reinforcement, network reinforcement and parallel string reinforcement. The effect of the two factors on tensile strength, tensile strain, bending strength, modulus of elasticity and modulus of bending were investigated. The results indicated that the two factors and their interactions had significant effects on the mentioned properties of bioplastics (at α=0.05 level . The comparison of the means of the tests showed that the network reinforcement type with 50% cellulose had the highest tensile and bending strengths with 1992.02 and 28.71 MPa, respectively. The maximum modulus of elasticity and modulus bending were 40.4 and 2.3 MPa, respectively for parallel string arrangement and 70% of cellulose. The degradability tests of bioplastic using a fistulated sheep indicated that with increasing the percentage of cellulose, the degradability rate deceased. The maximum degradability rate, after 48 h holding in the sheep rumen, was 74% that belonged to bioplastics with 50% cellulose. The degradability data were well fitted to a mathematical model (R2=0.97.

  9. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Greene, R.H.; Casada, D.A.; Ayers, C.W. [and others

    1995-08-01

    This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented.

  10. Thermal Degradation Studies of Polyurethane/POSS Nanohybrid Elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Lewicki, J P; Pielichowski, K; TremblotDeLaCroix, P; Janowski, B; Todd, D; Liggat, J J

    2010-03-05

    Reported here is the synthesis of a series of Polyurethane/POSS nanohybrid elastomers, the characterization of their thermal stability and degradation behavior at elevated temperatures using a combination of Thermal Gravimetric Analysis (TGA) and Thermal Volatilization Analysis (TVA). A series of PU elastomers systems have been formulated incorporating varying levels of 1,2-propanediol-heptaisobutyl-POSS (PHIPOSS) as a chain extender unit, replacing butane diol. The bulk thermal stability of the nanohybrid systems has been characterized using TGA. Results indicate that covalent incorporation of POSS into the PU elastomer network increase the non-oxidative thermal stability of the systems. TVA analysis of the thermal degradation of the POSS/PU hybrid elastomers have demonstrated that the hybrid systems are indeed more thermally stable when compared to the unmodified PU matrix; evolving significantly reduced levels of volatile degradation products and exhibiting a {approx}30 C increase in onset degradation temperature. Furthermore, characterization of the distribution of degradation products from both unmodified and hybrid systems indicate that the inclusion of POSS in the PU network is directly influencing the degradation pathways of both the soft and hard block components of the elastomers: The POSS/PU hybrid systems show reduced levels of CO, CO2, water and increased levels of THF as products of thermal degradation.

  11. Gas generation from transuranic waste degradation: an interim assessment

    Energy Technology Data Exchange (ETDEWEB)

    Molecke, M.A.

    1979-10-01

    A review of all available, applicable data pertaining to gas generation from the degradation of transuranic waste matrix material and packaging is presented. Waste forms are representative of existing defense-related TRU wastes and include cellulosics, plastics, rubbers, concrete, process sludges, and mild steel. Degradation mechanisms studied were radiolysis, thermal, bacterial, and chemical corrosion. Gas generation rates are presented in terms of moles of gas produced per year per drum, and in G(gas) values for radiolytic degradation. Comparison of generation rates is made, as is a discussion of potential short- and long-term concerns. Techniques for reducing gas generation rates are discussed. 6 figures, 10 tables.

  12. BACTERIAL METHYLMERCURY DEGRADATION IN FLORIDA EVERGLADES PEAT SEDIMENT

    Science.gov (United States)

    Methylmercury (MeHg) degradation was investigated along an eutrophication gradient in the Florida Everglades by quantifying 14CH4 and 14CO2 production after incubation of anaerobic sediments with [14C]MeHg. Degradation rate constants (k) were consistently <=0.1 d-1 and decreased ...

  13. Effect of grass species on NDF ruminal degradability and ...

    African Journals Online (AJOL)

    uzivatel

    For the evaluation of rumen degradation parameters and INDF, grass species, year, ... variability in the chemical composition and degradability parameters, reflecting a wide range in NDF quality .... silage processing and microorganisms, may be more susceptible to enzymatic attack, mainly in ..... of their rapid maturing rate.

  14. the effect of varying levels of supplements on degradability, gas

    African Journals Online (AJOL)

    ansi

    fibre) degradable fractions, respectively; a1 and b1 are the degradation rates (per h) of soluble and fibre fractions, respectively; lt is lag time. LSD - least significant difference. Although these values are lower than those of the current study, they ...

  15. Overview of restoration and management practices in the degraded ...

    African Journals Online (AJOL)

    The highest deforestation and forest degradation rates in Africa occur in the dry forests and woodlands where pressure for land is increasing, poverty is rampant, livelihood options are few and climate change effects are severe. This paper examines factors that cause land and forest degradation in the Sahel and dry forests ...

  16. DEGRADATION OF POLY(METHYL METHACRYLATE) IN SOLUTION

    Science.gov (United States)

    The rate of degradation of poly(methyl methacrylate) (PMMA) to methyl methacrylate (MMA) was investigated in the liquid phase with toluene as the solvent. The degradation experiments were carried out in a tubular flow reactor at 1000 psig (6.8 MPa) and at four different temperat...

  17. Dynamical Clustering of Exchange Rates

    OpenAIRE

    Fenn, Daniel J.; Porter, Mason A.; Mucha, Peter J; Mark McDonald; Stacy Williams; Johnson, Neil F.; Jones, Nick S

    2009-01-01

    We use techniques from network science to study correlations in the foreign exchange (FX) market over the period 1991--2008. We consider an FX market network in which each node represents an exchange rate and each weighted edge represents a time-dependent correlation between the rates. To provide insights into the clustering of the exchange rate time series, we investigate dynamic communities in the network. We show that there is a relationship between an exchange rate's functional role withi...

  18. Degradation of toluene-2,4-diamine by persulphate: kinetics, intermediates and degradation pathway.

    Science.gov (United States)

    Jiang, Yong-hai; Zhang, Jin-bao; Xi, Bei-dou; An, Da; Yang, Yu; Li, Ming-xiao

    2015-01-01

    In this study, the degradation of toluene-2,4-diamine (TDA) by persulphate (PS) in an aqueous solution at near-neutral pH was examined. The result showed that the degradation rate of TDA increased with increasing PS concentrations. The optimal dosage of PS in the reaction system was determined by efficiency indicator (I) coupling in the consumption of PS and decay half-life of TDA. Calculation showed that 0.74 mM of PS was the most effective dosage for TDA degradation, at that level the maximum I of 24.51 was obtained. PS can oxidize TDA for an extended reaction time period. Under neutral condition without activation, four degradation intermediates, 2,4-diamino-3-hydroxy-5-sulfonicacidtoluene, 2,4-diaminobenzaldehyde, 2,4-bis(vinylamino)benzaldehyde and 3,5-diamino-4-hydroxy-2-pentene, were identified by high-performance liquid chromatography-mass spectrometry. The tentative degradation pathway of TDA was proposed as well. It was found that hydroxyl radical played an important role in degradation of TDA with the activation of Fe2+, whereas PS anion and sulphate radicals were responsible for the degradation without activation of Fe2+.

  19. A Theoretical Model for Metal Corrosion Degradation

    Directory of Open Access Journals (Sweden)

    David V. Svintradze

    2010-01-01

    Full Text Available Many aluminum and stainless steel alloys contain thin oxide layers on the metal surface which greatly reduce the corrosion rate. Pitting corrosion, a result of localized breakdown of such films, results in accelerated dissolution of the underlying metal through pits. Many researchers have studied pitting corrosion for several decades and the exact governing equation for corrosion pit degradation has not been obtained. In this study, the governing equation for corrosion degradation due to pitting corrosion behavior was derived from solid-state physics and some solutions and simulations are presented and discussed.

  20. Controlling the Degradation of Bioresorbable Polymers

    Science.gov (United States)

    Moritz, Istvan; Crowley, Brian; Brundage, Elizabeth; Rende, Deniz; Ozisik, Rahmi

    Bioresorbable polymers play a vital role in the development of implantable materials that are used in surgical procedures, controlled drug delivery systems; and tissue engineering scaffolds. The half-life of common bioresorbable polymers ranges from 3 to over 12 months and slow bioresorption rates of these polymers restrict their use to a limited set of applications. The use of embedded enzymes was previously proposed to control the degradation rate of bioresorbable polymers, and was shown to decrease average degradation time to about 0.5 months. In this study, electromagnetic actuation of iron oxide magnetic nanoparticles embedded in an encapsulant polymer, poly(ethyleneoxide), PEO, was employed to initiate enzyme assisted degradation of bioresorbable polymer poly(caprolactone), PCL. Results indicate that the internal temperature of iron oxide magnetic nanoparticle doped PEO samples can be increased via an alternating magnetic field, and temperature increase depends strongly on nanoparticle concentration and magnetic field parameters. The temperature achieved is sufficient to relax the PEO matrix and to enable the diffusion of enzymes from PEO to a surrounding PCL matrix. Current studies are directed at measuring the degradation rate of PCL due to the diffused enzyme. This material is based upon work supported by the National Science Foundation under Grant No. CMMI-1538730.

  1. TALSPEAK Solvent Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Leigh R. Martin; Bruce J. Mincher

    2009-09-01

    Understanding the radiolytic degradation behavior of organic molecules involved in new or existing schemes for the recycle of used nuclear fuels is of significant interest for sustaining a closed nuclear fuel cycle. Here we have conducted several lines of investigation to begin understanding the effects of radiolysis on the aqueous phase of the TALSPEAK process for the separation of the trivalent lanthanides from the trivalent actinides. Using the 60-Co irradiator at the INL, we have begun to quantify the effects of radiation on the aqueous phase complexants used in this separation technique, and how this will affect the actinide lanthanide separation factor. In addition we have started to develop methodologies for stable product identification, a key element in determining the degradation pathways. We have also introduced a methodology to investigate the effects of alpha radiolysis that has previously received limited attention.

  2. Designing degradable hydrogels for orthogonal control of cell microenvironments

    Science.gov (United States)

    Kharkar, Prathamesh M.

    2013-01-01

    Degradable and cell-compatible hydrogels can be designed to mimic the physical and biochemical characteristics of native extracellular matrices and provide tunability of degradation rates and related properties under physiological conditions. Hence, such hydrogels are finding widespread application in many bioengineering fields, including controlled bioactive molecule delivery, cell encapsulation for controlled three-dimensional culture, and tissue engineering. Cellular processes, such as adhesion, proliferation, spreading, migration, and differentiation, can be controlled within degradable, cell-compatible hydrogels with temporal tuning of biochemical or biophysical cues, such as growth factor presentation or hydrogel stiffness. However, thoughtful selection of hydrogel base materials, formation chemistries, and degradable moieties is necessary to achieve the appropriate level of property control and desired cellular response. In this review, hydrogel design considerations and materials for hydrogel preparation, ranging from natural polymers to synthetic polymers, are overviewed. Recent advances in chemical and physical methods to crosslink hydrogels are highlighted, as well as recent developments in controlling hydrogel degradation rates and modes of degradation. Special attention is given to spatial or temporal presentation of various biochemical and biophysical cues to modulate cell response in static (i.e., non-degradable) or dynamic (i.e., degradable) microenvironments. This review provides insight into the design of new cell-compatible, degradable hydrogels to understand and modulate cellular processes for various biomedical applications. PMID:23609001

  3. [Effects of nitrogen and phosphorus fertilizer on atrazine degradation and detoxification by degrading strain HB-5].

    Science.gov (United States)

    Su, Jun; Zhu, Lu-Sheng; Li, Xu-Hua; Wang, Jun; Xie, Hui; Wang, Jin-Hua; Wang, Qi; Jia, Wen-Tao

    2010-10-01

    An atrazine-degrading strain HB-5 was used as a bacteria for biodegradation. Treatments of soil with nitrogen single, phosphate single and nitrogen phosphate together with HB-5 were carried out for degradation and eco-toxicity test; then, relationship between atrazine degradation rate and soil available nitrogen, available phosphorus were discussed. Atrazine residues were determined by HPLC; available nitrogen was determined with alkaline hydrolysis diffusion method; available phosphorus was determined with 0.5 mol/L-NaHCO3 extraction and molybdenum stibium anti-color method, and toxicity test was carried out with micronucleus test of Vicia faba root tip cells. The results showed that: After separately or together application, nitrogenous and phosphorous fertilizers could significantly accelerate atrazine degradation than soil with HB-5 only. On day 5, the order of atrazine degradation was ANP > AP > AN > A; 7 days later, no statistically significant differences were found between treatments. The available nitrogen and phosphorus level in soil reduced as the degradation rate increased in the soil. The soil of eco-toxicity test results indicated that the eco-toxicity significantly reduced with the degradation of atrazine by HB-5, and the eco-toxicity on treatments of soil with fertilizer were all below the treatments without fertilizer. On day 5, the order of eco-toxicity was ANP < AP < AN < A; 7 days later, all treatments were decreased in control levels. So, adjusting soil nutrient content could not only promote atrazine degradation in soil but also could reduce the soil eco-toxicity effects that atrazine caused. All these results could be keystone of atrazine pollution remediation in contaminated soil in the future.

  4. Microbial degradation of petroleum hydrocarbons.

    Science.gov (United States)

    Varjani, Sunita J

    2017-01-01

    Petroleum hydrocarbon pollutants are recalcitrant compounds and are classified as priority pollutants. Cleaning up of these pollutants from environment is a real world problem. Bioremediation has become a major method employed in restoration of petroleum hydrocarbon polluted environments that makes use of natural microbial biodegradation activity. Petroleum hydrocarbons utilizing microorganisms are ubiquitously distributed in environment. They naturally biodegrade pollutants and thereby remove them from the environment. Removal of petroleum hydrocarbon pollutants from environment by applying oleophilic microorganisms (individual isolate/consortium of microorganisms) is ecofriendly and economic. Microbial biodegradation of petroleum hydrocarbon pollutants employs the enzyme catalytic activities of microorganisms to enhance the rate of pollutants degradation. This article provides an overview about bioremediation for petroleum hydrocarbon pollutants. It also includes explanation about hydrocarbon metabolism in microorganisms with a special focus on new insights obtained during past couple of years. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Rate based failure detection

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Brett Emery Trabun; Gamage, Thoshitha Thanushka; Bakken, David Edward

    2018-01-02

    This disclosure describes, in part, a system management component and failure detection component for use in a power grid data network to identify anomalies within the network and systematically adjust the quality of service of data published by publishers and subscribed to by subscribers within the network. In one implementation, subscribers may identify a desired data rate, a minimum acceptable data rate, desired latency, minimum acceptable latency and a priority for each subscription. The failure detection component may identify an anomaly within the network and a source of the anomaly. Based on the identified anomaly, data rates and or data paths may be adjusted in real-time to ensure that the power grid data network does not become overloaded and/or fail.

  6. Volatile hydrocarbons inhibit methanogenic crude oil degradation

    Directory of Open Access Journals (Sweden)

    Angela eSherry

    2014-04-01

    Full Text Available Methanogenic degradation of crude oil in subsurface sediments occurs slowly, but without the need for exogenous electron acceptors, is sustained for long periods and has enormous economic and environmental consequences. Here we show that volatile hydrocarbons are inhibitory to methanogenic oil biodegradation by comparing degradation of an artificially weathered crude oil with volatile hydrocarbons removed, with the same oil that was not weathered. Volatile hydrocarbons (nC5-nC10, methylcyclohexane, benzene, toluene and xylenes were quantified in the headspace of microcosms. Aliphatic (n-alkanes nC12-nC34 and aromatic hydrocarbons (4-methylbiphenyl, 3-methylbiphenyl, 2-methylnaphthalene, 1-methylnaphthalene were quantified in the total hydrocarbon fraction extracted from the microcosms. 16S rRNA genes from key microorganisms known to play an important role in methanogenic alkane degradation (Smithella and Methanomicrobiales were quantified by quantitative PCR. Methane production from degradation of weathered oil in microcosms was rapid (1.1 ± 0.1 µmol CH4/g sediment/day with stoichiometric yields consistent with degradation of heavier n-alkanes (nC12-nC34. For non-weathered oil, degradation rates in microcosms were significantly lower (0.4 ± 0.3 µmol CH4/g sediment/day. This indicated that volatile hydrocarbons present in the non-weathered oil inhibit, but do not completely halt, methanogenic alkane biodegradation. These findings are significant with respect to rates of biodegradation of crude oils with abundant volatile hydrocarbons in anoxic, sulphate-depleted subsurface environments, such as contaminated marine sediments which have been entrained below the sulfate-reduction zone, as well as crude oil biodegradation in petroleum reservoirs and contaminated aquifers.

  7. Biogeochemical Cycles in Degraded Lands

    Science.gov (United States)

    Davidson, Eric A.; Vieira, Ima Celia G.; ReisdeCarvalho, Claudio Jose; DeanedeAbreuSa, Tatiana; deSouzaMoutinho, Paulo R.; Figueiredo, Ricardo O.; Stone, Thomas A.

    2004-01-01

    The objectives of this project were to define and describe the types of landscapes that fall under the broad category of "degraded lands" and to study biogeochemical cycles across this range of degradation found in secondary forests. We define degraded land as that which has lost part of its capacity of renovation of a productive ecosystem, either in the context of agroecosystems or as native communities of vegetation. This definition of degradation permits evaluation of biogeochemical constraints to future land uses.

  8. Lactose contaminant as steroid degradation enhancer.

    Science.gov (United States)

    Nieuwmeyer, Florentine; van der Voort Maarschalk, Kees; Vromans, Herman

    2008-11-01

    By pharmaceutical processes and in the presence of solid excipients physical-chemical changes are known to occur, leading to increased rate of chemical degradation. The purpose of this work was to determine the critical aspects in the stability of a steroid in the presence of a commonly used excipient, lactose. A steroid was either mixed or wet granulated with lactose with different particle size. Small lactose particles lead to a higher degree of degradation. Degradation was enhanced under warm humid conditions although the presence of water alone could not account for this effect. Lactose-phosphate, a known intrinsic contaminant in lactose is demonstrated to enhance the degradation of the steroid. Stability was improved in high purity lactose and deteriorated upon extra addition of phosphates. Since the exposure to the contaminant is a function of the surface area of the lactose, particle size differences of the excipient have a clear consequence. High shear granulated lactose granules exhibit a heterogeneous composition; large granules consist of small primary particles and vice versa. It is shown that the large granules, composed of the small primary lactose particles reveal the highest degree of degradation. Granule composition dictates the stability profile of the granules. The lactose contaminant and granule composition dictates the stability profile of the granules and mixtures.

  9. Degradation of chlorpyrifos in tropical rice soils.

    Science.gov (United States)

    Das, Subhasis; Adhya, Tapan K

    2015-04-01

    Chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridinol) phosphorothioate] is used worldwide as an agricultural insecticide against a broad spectrum of insect pests of economically important crops including rice, and soil application to control termites. The insecticide mostly undergoes hydrolysis to diethyl thiophosphoric acid (DETP) and 3,5,6-trichloro-2-pyridinol (TCP), and negligible amounts of other intermediate products. In a laboratory-cum-greenhouse study, chlorpyrifos, applied at a rate of 10 mg kg(-1) soil to five tropical rice soils of wide physico-chemical variability, degraded with a half-life ranging from 27.07 to 3.82 days. TCP was the major metabolite under both non-flooded and flooded conditions. Chlorpyrifos degradation had significant negative relationship with electrical conductivity (EC), cation exchange capacity (CEC), clay and sand contents of the soils under non-flooded conditions. Results indicate that degradation of chlorpyrifos was accelerated with increase in its application frequency, across the representative rice soils. Management regimes including moisture content and presence or absence of rice plants also influenced the process. Biotic factors also play an important role in the degradation of chlorpyrifos as demonstrated by its convincing degradation in mineral salts medium inoculated with non-sterile soil suspension. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Maximizing microbial perchlorate degradation using a genetic algorithm: consortia optimization.

    Science.gov (United States)

    Kucharzyk, Katarzyna H; Soule, Terence; Hess, Thomas F

    2013-09-01

    Microorganisms in consortia perform many tasks more effectively than individual organisms and in addition grow more rapidly and in greater abundance. In this work, experimental datasets were assembled consisting of all possible selected combinations of perchlorate reducing strains of microorganisms and their perchlorate degradation rates were evaluated. A genetic algorithm (GA) methodology was successfully applied to define sets of microbial strains to achieve maximum rates of perchlorate degradation. Over the course of twenty generations of optimization using a GA, we saw a statistically significant 2.06 and 4.08-fold increase in average perchlorate degradation rates by consortia constructed using solely the perchlorate reducing bacteria (PRB) and by consortia consisting of PRB and accompanying organisms that did not degrade perchlorate, respectively. The comparison of kinetic rates constant in two types of microbial consortia additionally showed marked increases.

  11. Legume-Cereal Intercropping Improves Forage Yield, Quality and Degradability.

    Science.gov (United States)

    Zhang, Jie; Yin, Binjie; Xie, Yuhuai; Li, Jing; Yang, Zaibin; Zhang, Guiguo

    2015-01-01

    Intercropping legume with cereal is an extensively applied planting pattern in crop cultivation. However, forage potential and the degradability of harvested mixtures from intercropping system remain unclear. To investigate the feasibility of applying an intercropping system as a forage supply source to ruminants, two consecutive experiments (experiments 1 and 2) involving a field cultivation trial and a subsequent in vivo degradable experiment were conducted to determine the forage production performance and the ruminally degradable characteristics of a harvested mixture from an alfalfa/corn-rye intercropping system. In experiment 1, the intercropping system was established by alternating alfalfa and corn or rye with a row ratio of 5:2. Dry matter (DM) and nutrient yields were determined. In experiment 2, forages harvested from the different treatments were used as feedstuff to identify nutrient degradation kinetics and distribution of components between the rapidly degradable (a), potentially degradable (b) and the degradation rate constant (c) of 'b' fraction by in sacco method in Small-Tail Han wether Sheep. The intercropping system of alfalfa and corn-rye provided higher forage production performance with net increases of 9.52% and 34.81% in DM yield, 42.13% and 16.74% in crude protein (CP) yield, 25.94% and 69.99% in degradable DM yield, and 16.96% and 5.50% in degradable CP yield than rotation and alfalfa sole cropping systems, respectively. In addition, the harvest mixture from intercropping system also had greater 'a' fraction, 'b' fraction, 'c' values, and effective degradability (E value) of DM and CP than corn or rye hay harvested from rotation system. After 48-h exposure to rumen microbes, intercropping harvest materials were degraded to a higher extent than separately degraded crop stems from the sole system as indicated by visual microscopic examination with more tissues disappeared. Thus, the intercropping of alfalfa and corn-rye exhibited a greater

  12. Degradation of polyvinyl alcohol (PVA) by UV/chlorine oxidation: Radical roles, influencing factors, and degradation pathway.

    Science.gov (United States)

    Ye, Bei; Li, Yue; Chen, Zhuo; Wu, Qian-Yuan; Wang, Wen-Long; Wang, Ting; Hu, Hong-Ying

    2017-11-01

    Polyvinyl alcohol (PVA) is widely used in industry but is difficult to degrade. In this study, the synergistic effect of UV irradiation and chlorination on degradation of PVA was investigated. UV irradiation or chlorination alone did not degrade PVA. By contrast, UV/chlorine oxidation showed good efficiency for PVA degradation via generation of active free radicals, such as OH and Cl. The relative importance of these two free radicals in the oxidation process was evaluated, and it was shown that OH contributed more to PVA degradation than Cl did. The degradation of PVA followed pseudo first order kinetics. The rate constant k increased linearly from 0 min-1 to 0.3 min-1 with increasing chlorine dosage in range of 0 mg/L to 20 mg/L. However, when the chlorine dosage was increased above 20 mg/L, scavenging effect of free radicals occurred, and the degradation efficiency of PVA did not increase much more. Acidic media increased the degradation efficiency of PVA by UV/chlorine oxidation more than basic or neutral media because of the higher ratio of [HOCl]/[OCl-], higher free radical quantum yields, and the lower free radical quenching effect under acidic conditions. Results of Fourier Transform Infrared Spectroscopy showed that carbonyl groups in degradation products were formed during UV/chlorine oxidation, and a possible degradation pathway via alcohol to carbonyl was proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Degradation of Sodium-Polyacrylate in Dilute Aqueous Solution, II

    Science.gov (United States)

    Saita, Takao; Matumura, On

    1983-08-01

    It has been found that Na-PAA molecules in dilute aqueous solution are degraded by shearing stress, oxidation and photolysis during usual viscosity measurements with a capillary viscometer. The results of previous viscosity measurements, mainly about the mechanochemical degradation in air and in air-free conditions, showed that the degradation rate increases with increasing shear stress, and with decreasing polymer concentration. In this work, the effects of the molecular weight and temperature on the degradation rate are measured using a capillary viscometer in air, and the photodegradation of Na-PAA and PAA in aqueous solution irradiated with UV light are studied by viscosity measurements in air, and by UV absorption and ESR methods. The results show that the degradation of molecules is enhanced by an increase in the molecular weight and strongly accelerated by a rise in temperature and by UV irradiation, and is accompanied by free-radical chain reactions.

  14. Upregulation of cognitive control networks in older adults’ speech comprehension

    Directory of Open Access Journals (Sweden)

    Julia eErb

    2013-12-01

    Full Text Available Speech comprehension abilities decline with age and with age-related hearing loss, but it is unclear how this decline expresses in terms of central neural mechanisms. The current study examined neural speech processing in a group of older adults (aged 56–77, n=16, with varying degrees of sensorineural hearing loss, and compared them to a cohort of young adults (aged 22–31, n=30, self-reported normal hearing. In an fMRI experiment, listeners heard and repeated back degraded sentences (4-band vocoding, which preserves the temporal envelope of the acoustic signal, while substantially degrading spectral information. Behaviourally, older adults adapted to degraded speech at the same rate as young listeners, although their overall comprehension of degraded speech was lower. Neurally, both older and young adults relied on the left anterior insula for degraded more than clear speech perception. However, anterior insula engagement in older adults was dependent on hearing acuity. Young adults additionally employed the anterior cingulate cortex (ACC. Interestingly, this age group × degradation interaction was driven by a reduced dynamic range in older adults, who displayed elevated levels of ACC activity in both conditions, consistent with a persistent upregulation in cognitive control irrespective of task difficulty. For correct speech comprehension, older adults recruited the middle frontal gyrus in addition to a core speech comprehension network on which young adults relied, suggestive of a compensatory mechanism. Taken together, the results indicate that older adults increasingly recruit cognitive control networks, even under optimal listening conditions, at the expense of these systems’ dynamic range.

  15. ENHANCED DEGRADATION OF CAPTAN BY IMMOBILIZED CELLS OF BACILLUS CIRCULANS

    Directory of Open Access Journals (Sweden)

    Veena More

    2014-10-01

    Full Text Available The possibility of using Bacillus circulans in degrading captan was evaluated by comparing the captan degradation rate by freely suspended and immobilized cells on agar, sodium alginate (SA, polyacrylamide (PA and polyurethane-foam (PUF in batch and repeated batch degradations. Under batch degradations, 50, 60, 72, and 88% of 0.1% captan was degraded by freely suspended cells, agar-, SA-, and PA-immobilized cells, respectively in 72 h; whereas 15, 47.5, 67.7 and 75% of 0.2% captan was degraded by freely suspended cells, agar-, SA-, and PA-immobilized cells, respectively in 72 h. However, 0.1 and 0.2% captan were completely degraded by PUF-immobilized cells in 48 and 72 h, respectively. Under repeated batch degradations, PUF-immobilized cells were reused more than 40 cycles for 72 h without losing the captan degradation ability, while the cells immobilized on agar, SA, and the PA could be reused for 15, 20, and 25 cycles, respectively. A significant 0.1% captan degradation by PUF-immobilized cells was observed at pH 4.0 - 10.0 and 20 - 40 ºC ranges. In contrast, freely suspended cells only degraded captan at optimum pH of 7.0 and 30 ºC. The PUF-immobilized cells were able to significantly degrade captan for 120 days at 4 ºC without losing the captan degradation ability; whereas this ability was lost in 120 days for freely suspended cells. Since the application of captan leads to pollution and reduces soil fertility, the use of immobilized cells of Bacillus circulans can thus be a better cost-effective strategy to decontaminate captan polluted sites.

  16. Enzymatic degradation behavior of nanoclay reinforced biodegradable PLA/PBSA blend composites.

    Science.gov (United States)

    Malwela, Thomas; Ray, Suprakas Sinha

    2015-01-01

    Films of a biodegradable PLA/PBSA blend and blend-composites containing 2wt% of C20A, C30B and MEE were prepared by solvent casting and spin coating. The films were incubated in vials containing Tris-HCl buffer with Proteinase K, and their weight losses were measured after enzymatic degradation. The surface morphology before and after degradation tests was studied by SEM and in situ AFM. The results showed that neat PLA had a lower percentage weight loss than neat PBSA, whereas blending them resulted in an increased weight loss. The incorporation of C20A into the as-prepared blend accelerated the degradation rate, whereas C30B and MEE decelerated the degradation rate. Annealing at 70°C reduced the degradation rate of the blend, and the presence of nanoclays further reduced the degradation rates. Annealing at 120°C dramatically decelerated the degradation of the blend, whereas the incorporation of nanoclays accelerated the degradations rates. The enhancement of the degradation rates in the presence of nanoclays indicated that the degradation rates were mainly controlled by the PLA matrix. Thin films were also cast onto a silicon substrate using a spin coater, and enzymatic degradation on the completely crystalline surfaces revealed that enzymatic attack occurred by pitting and surface erosion of the thin films. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Efeito do acipin sobre a degradabilidade e taxa de passagem de silagens de capim-elefante e de milho, em bovinos Holandês × Zebu Effect of acipin on the degradability and rate of passage of elephant-grass and corn silages in Holstein × Zebu cattle

    Directory of Open Access Journals (Sweden)

    L.T. Henriques

    2004-12-01

    Full Text Available Avaliou-se o efeito da inclusão de acipin nas silagens de capim-elefante e de milho sobre a taxa de passagem das fases sólida e líquida da digesta ruminal e sobre a degradabilidade da matéria seca (MS, proteína bruta (PB e fibra em detergente neutro (FDN, em quatro bovinos. Os animais, com média de peso de 550kg, foram confinados em baias individuais por 90 dias. O experimento foi conduzido em quatro períodos experimentais, seguindo um esquema de parcelas subdivididas, tendo nas parcelas um esquema fatorial 2×2 (duas silagens combinadas com ausência e presença de acipin e nas subparcelas o tempo de coleta de líquido ruminal, em delineamento inteiramente ao acaso com quatro repetições. A degradabilidade efetiva da MS, da PB e da FDN da silagem de capim-elefante sem adição de acipin foi menor do que a das silagens de capim-elefante com acipin, de milho sem acipin e de milho com acipin; estas foram semelhantes entre si. A taxa de passagem de sólidos ruminais foi maior nos animais que consumiram silagem de milho. A taxa de passagem de líquidos foi maior nos animais que consumiram silagem de capim-elefante. A inclusão de acipin melhorou a degradabilidade da MS, da PB e da FDN da silagem de capim-elefante.The effects of adding acipin to elephantgrass and corn silages on the passage rates of the solid and liquid phases of the ruminal digesta, and on degradabilities of dry matter (DM, crude protein (CP and neutral detergent fiber (NDF were evaluated. The animals with average live weight of 550kg, were kept in individual stalls for 90 days. The experiment was carried out in four experimental periods, according to a split plot arrangement, with 2×2 (two silages combined with absence or presence of acipin factorial treatment combination in the plot and the time of collection of ruminal liquid in the split plot, in a completely randomized design with four replicates. The degradabilities of DM, CP and NDF in the elephantgrass silage

  18. Membrane degradation mechanisms in polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Mittal, Vishal Onkarmal

    Membrane degradation and failure is one of the most important factors limiting the lifetime of polymer electrolyte membrane fuel cells (PEMFCs). Increasing the membrane life by developing degradation mitigation strategies in the cell or developing a new membrane with improved life requires a detailed understanding of the membrane degradation mechanism during operation in a PEMFC. An in-situ and nondestructive technique, which relies on the measurement of the membrane degradation rate in a fuel cell, was used to study the chemical/electrochemical mode of membrane degradation. NafionRTM membrane was used for the degradation study and fluoride emission rate (FER) as measured from the fuel cell effluent water analysis was used as a quantitative indicator of the membrane degradation rate. The degradation mechanism was studied by a detailed investigation of the effect of reactants, catalyst properties (location, potential, catalyst type, interaction with O2 and H2O), cell current, membrane thickness, NafionRTM counterion, and direction of water movement on the membrane degradation rate. Based on the experimental findings it is shown that commonly known membrane degradation mechanisms involving formation of active oxygen species from H 2O2 decomposition or the direct formation of active oxygen species in the oxygen reduction reaction are not the dominating membrane degradation mechanisms in PEMFCs. It is proposed that molecular H2 and O 2 react on the surface of Pt catalyst to form the membrane degrading species. Depending upon the catalyst location the source of H2 or O2 or both is from the reactant crossover through the membrane. The reaction mechanism is chemical in nature and depends upon the catalyst surface properties and the relative concentrations of H2 and O 2 at the catalyst. The membrane degradation rate also depends on the residence time of the species in the membrane and the reaction volume i.e. the membrane thickness. Thus, the membrane degradation may not

  19. DSNF and other waste form degradation abstraction

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, Thomas A.

    2000-12-20

    The purpose of this analysis/model report (AMR) is to select and/or abstract conservative degradation models for DOE-(US. Department of Energy) owned spent nuclear fuel (DSNF) and the immobilized ceramic plutonium (Pu) disposition waste forms for application in the proposed monitored geologic repository (MGR) postclosure Total System Performance Assessment (TSPA). Application of the degradation models abstracted herein for purposes other than TSPA should take into consideration the fact that they are, in general, very conservative. Using these models, the forward reaction rate for the mobilization of radionuclides, as solutes or colloids, away from the waste fondwater interface by contact with repository groundwater can then be calculated. This forward reaction rate generally consists of the dissolution reaction at the surface of spent nuclear fuel (SNF) in contact with water, but the degradation models, in some cases, may also include and account for the physical disintegration of the SNF matrix. The models do not, however, account for retardation, precipitation, or inhibition of the migration of the mobilized radionuclides in the engineered barrier system (EBS). These models are based on the assumption that all components of the DSNF waste form are released congruently with the degradation of the matrix.

  20. Rate of caesarean sections according to the Robson classification: Analysis in a French perinatal network - Interest and limitations of the French medico-administrative data (PMSI).

    Science.gov (United States)

    Lafitte, A-S; Dolley, P; Le Coutour, X; Benoist, G; Prime, L; Thibon, P; Dreyfus, M

    2018-02-01

    The objective of our study was to determine, in accordance with WHO recommendations, the rates of Caesarean sections in a French perinatal network according to the Robson classification and determine the benefit of the medico-administrative data (PMSI) to collect this indicator. This study aimed to identify the main groups contributing to local variations in the rates of Caesarean sections. A descriptive multicentric study was conducted in 13 maternity units of a French perinatal network. The rates of Caesarean sections and the contribution of each group of the Robson classification were calculated for all Caesarean sections performed in 2014. The agreement of the classification of Caesarean sections according to Robson using medico-administrative data and data collected in the patient records was measured by the Kappa index. We also analysed a 6 groups simplified Robson classification only using data from PMSI, which do not inform about parity and onset of labour. The rate of Caesarean sections was 19% (14.5-33.2) in 2014 (2924 out of 15413 deliveries). The most important contributors to the total rates were groups 1, 2 and 5, representing respectively 14.3%, 16.7% and 32.1% of the Caesarean sections. The rates were significantly different in level 1, 2b and 3 maternity units in groups 1 to 4, level 2a maternity units in group 5, and level 3 maternity units in groups 6 and 7. The agreement between the simplified Robson classification produced using the medical records and the medico-administrative data was excellent, with a Kappa index of 0.985 (0.980-0.990). To reduce the rates of Caesarean sections, audits should be conducted on groups 1, 2 and 5 and local protocols developed. Simply by collecting the parity data, the excellent metrological quality of the medico-administrative data would allow systematisation of the Robson classification for each hospital. Copyright © 2017. Published by Elsevier Masson SAS.