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Sample records for extreme ph values

  1. Extreme value distributions

    CERN Document Server

    Ahsanullah, Mohammad

    2016-01-01

    The aim of the book is to give a through account of the basic theory of extreme value distributions. The book cover a wide range of materials available to date. The central ideas and results of extreme value distributions are presented. The book rwill be useful o applied statisticians as well statisticians interrested to work in the area of extreme value distributions.vmonograph presents the central ideas and results of extreme value distributions.The monograph gives self-contained of theory and applications of extreme value distributions.

  2. Eukaryotic diversity at pH extremes

    Directory of Open Access Journals (Sweden)

    Linda A. Amaral-Zettler

    2013-01-01

    Full Text Available Extremely acidic (pH<3 and extremely alkaline (pH>9 environments support a diversity of single-cell and to a lesser extent, multicellular eukaryotic life. This study compared alpha and beta diversity in eukaryotic communities from 7 diverse aquatic environments with pH values ranging from 2 to 11 using massively-parallel pyrotag sequencing targeting the V9 hypervariable region of the 18S ribosomal RNA (rRNA gene. A total of 946 Operational Taxonomic Units (OTUs were recovered at a 6% cut-off level (94% similarity across the sampled environments. Hierarchical clustering of the samples segregated the communities into acidic and alkaline groups. Similarity Percentage Analysis (SIMPER followed by Indicator OTU Analysis (IOA and Non-metric Multidimensional Scaling (NMDS were used to determine which characteristic groups of eukaryotic taxa typify acidic or alkaline extremes and the extent to which pH explains eukaryotic community structure in these environments. Spain’s Rio Tinto yielded the fewest observed OTUs while Nebraska Sandhills alkaline lakes yielded the most. Distinct OTUs, including metazoan OTUs, numerically dominated pH extreme sites. Indicator OTUs included the diatom Pinnularia and unidentified opisthokonts (Fungi and Filasterea in the extremely acidic environments, and the ciliate Frontonia across the extremely alkaline sites. Inferred from NMDS, pH explained only a modest fraction of the variation across the datasets, indicating that other factors influence the underlying community structure in these environments. The findings from this study suggest that the ability for eukaryotes to adapt to pH extremes over a broad range of values may be rare, but further study of taxa that can broadly adapt across diverse acidic and alkaline environments respectively present good models for understanding adaptation and should be targeted for future investigations.

  3. Eukaryotic diversity at pH extremes.

    Science.gov (United States)

    Amaral-Zettler, Linda A

    2012-01-01

    Extremely acidic (pH 9) environments support a diversity of single-cell and to a lesser extent, multicellular eukaryotic life. This study compared alpha and beta diversity in eukaryotic communities from seven diverse aquatic environments with pH values ranging from 2 to 11 using massively-parallel pyrotag sequencing targeting the V9 hypervariable region of the 18S ribosomal RNA (rRNA) gene. A total of 946 operational taxonomic units (OTUs) were recovered at a 6% cut-off level (94% similarity) across the sampled environments. Hierarchical clustering of the samples segregated the communities into acidic and alkaline groups. Similarity percentage (SIMPER) analysis followed by indicator OTU analysis (IOA) and non-metric multidimensional scaling (NMDS) were used to determine which characteristic groups of eukaryotic taxa typify acidic or alkaline extremes and the extent to which pH explains eukaryotic community structure in these environments. Spain's Rio Tinto yielded the fewest observed OTUs while Nebraska Sandhills alkaline lakes yielded the most. Distinct OTUs, including metazoan OTUs, numerically dominated pH extreme sites. Indicator OTUs included the diatom Pinnularia and unidentified opisthokonts (Fungi and Filasterea) in the extremely acidic environments, and the ciliate Frontonia across the extremely alkaline sites. Inferred from NMDS, pH explained only a modest fraction of the variation across the datasets, indicating that other factors influence the underlying community structure in these environments. The findings from this study suggest that the ability for eukaryotes to adapt to pH extremes over a broad range of values may be rare, but further study of taxa that can broadly adapt across diverse acidic and alkaline environments, respectively present good models for understanding adaptation and should be targeted for future investigations.

  4. Applied extreme-value statistics

    Energy Technology Data Exchange (ETDEWEB)

    Kinnison, R.R.

    1983-05-01

    The statistical theory of extreme values is a well established part of theoretical statistics. Unfortunately, it is seldom part of applied statistics and is infrequently a part of statistical curricula except in advanced studies programs. This has resulted in the impression that it is difficult to understand and not of practical value. In recent environmental and pollution literature, several short articles have appeared with the purpose of documenting all that is necessary for the practical application of extreme value theory to field problems (for example, Roberts, 1979). These articles are so concise that only a statistician can recognise all the subtleties and assumptions necessary for the correct use of the material presented. The intent of this text is to expand upon several recent articles, and to provide the necessary statistical background so that the non-statistician scientist can recognize and extreme value problem when it occurs in his work, be confident in handling simple extreme value problems himself, and know when the problem is statistically beyond his capabilities and requires consultation.

  5. Extreme Value Theory and Value at Risk

    Directory of Open Access Journals (Sweden)

    Viviana Fernandez

    2003-03-01

    Full Text Available Value at Risk (VaR is a measure of the maximum potential change in value of a portfolio of financial assets with a given probability over a given time horizon. VaR became a key measure of market risk since the Basle Committee stated that banks should be able to cover losses on their trading portfolios over a ten-day horizon, 99 percent of the time. A common practice is to compute VaR by assuming that changes in value of the portfolio are normally distributed, conditional on past in-formation. However, assets returns usually come from fat-tailed distri-butions. Therefore, computing VaR under the assumption of conditional normality can be an important source of error. We illustrate this point with Chilean and U.S. returns series by resorting to extreme value theory (EVT and GARCH-type models. In addition, we show that dynamic estimation of empirical quantiles can also give more accurate VaR estimates than quantiles of a standard normal.

  6. Predictability of extreme values in geophysical models

    Directory of Open Access Journals (Sweden)

    A. E. Sterk

    2012-09-01

    Full Text Available Extreme value theory in deterministic systems is concerned with unlikely large (or small values of an observable evaluated along evolutions of the system. In this paper we study the finite-time predictability of extreme values, such as convection, energy, and wind speeds, in three geophysical models. We study whether finite-time Lyapunov exponents are larger or smaller for initial conditions leading to extremes. General statements on whether extreme values are better or less predictable are not possible: the predictability of extreme values depends on the observable, the attractor of the system, and the prediction lead time.

  7. Predictability of extreme values in geophysical models

    NARCIS (Netherlands)

    Sterk, A.E.; Holland, M.P.; Rabassa, P.; Broer, H.W.; Vitolo, R.

    2012-01-01

    Extreme value theory in deterministic systems is concerned with unlikely large (or small) values of an observable evaluated along evolutions of the system. In this paper we study the finite-time predictability of extreme values, such as convection, energy, and wind speeds, in three geophysical model

  8. Extreme Value distribution for singular measures

    CERN Document Server

    Faranda, Davide; Turchetti, Giorgio; Vaienti, Sandro

    2011-01-01

    In this paper we perform an analytical and numerical study of Extreme Value distributions in discrete dynamical systems that have a singular measure. Using the block maxima approach described in Faranda et al. [2011] we show that, numerically, the Extreme Value distribution for these maps can be associated to the Generalised Extreme Value family where the parameters scale with the information dimension. The numerical analysis are performed on a few low dimensional maps. For the middle third Cantor set and the Sierpinskij triangle obtained using Iterated Function Systems, experimental parameters show a very good agreement with the theoretical values. For strange attractors like Lozi and H\\`enon maps a slower convergence to the Generalised Extreme Value distribution is observed. Even in presence of large statistics the observed convergence is slower if compared with the maps which have an absolute continuous invariant measure. Nevertheless and within the uncertainty computed range, the results are in good agree...

  9. Extreme values, regular variation and point processes

    CERN Document Server

    Resnick, Sidney I

    1987-01-01

    Extremes Values, Regular Variation and Point Processes is a readable and efficient account of the fundamental mathematical and stochastic process techniques needed to study the behavior of extreme values of phenomena based on independent and identically distributed random variables and vectors It presents a coherent treatment of the distributional and sample path fundamental properties of extremes and records It emphasizes the core primacy of three topics necessary for understanding extremes the analytical theory of regularly varying functions; the probabilistic theory of point processes and random measures; and the link to asymptotic distribution approximations provided by the theory of weak convergence of probability measures in metric spaces The book is self-contained and requires an introductory measure-theoretic course in probability as a prerequisite Almost all sections have an extensive list of exercises which extend developments in the text, offer alternate approaches, test mastery and provide for enj...

  10. Negative pH and extremely acidic mine waters from Iron Mountain, California

    Science.gov (United States)

    Nordstrom, D.K.; Alpers, C.N.; Ptacek, C.J.; Blowes, D.W.

    2000-01-01

    Extremely acidic mine waters with pH values as low as -3.6, total dissolved metal concentrations as high as 200 g/L, and sulfate concentrations as high as 760 g/L, have been encountered underground in the Richmond Mine at Iron Mountain, CA. These are the most acidic waters known. The pH measurements were obtained by using the Pitzer method to define pH for calibration of glass membrane electrodes. The calibration of pH below 0.5 with glass membrane electrodes becomes strongly nonlinear but is reproducible to a pH as low as -4. Numerous efflorescent minerals were found forming from these acid waters. These extreme acid waters were formed primarily by pyrite oxidation and concentration by evaporation with minor effects from aqueous ferrous iron oxidation and efflorescent mineral formation.

  11. Value-at-Risk and Extreme Returns

    NARCIS (Netherlands)

    J. Daníelsson (Jón); C.G. de Vries (Casper)

    1997-01-01

    textabstractAccurate prediction of the frequency of extreme events is of primary importance in many financial applications such as Value-at-Risk (VaR) analysis. We propose a semi-parametric method for VaR evaluation. The largest risks are modelled parametrically, while smaller risks are captured by

  12. Dependency in Hydrological Extreme Value Analysis.

    OpenAIRE

    Boniphace, Edwin

    2012-01-01

    Contents Dedication i Acknowledgments iii Contents v List of Figures vii 1 Introduction 1 1.1 Extreme value theory . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Sum plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 Quantile-quantile plots . . . . . . . . . . . . . . . . . . . . . . . 5 1.4 Impact of dependence in data on qq-plots . . . . . . . . . . . . 6 1.5 Scope of this thesis . . . . . . . . . . . . . . . . . . . . . . . . . 10 ...

  13. Value-at-Risk and Extreme Returns

    NARCIS (Netherlands)

    J. Daníelsson (Jón); C.G. de Vries (Casper)

    1997-01-01

    textabstractAccurate prediction of the frequency of extreme events is of primary importance in many financial applications such as Value-at-Risk (VaR) analysis. We propose a semi-parametric method for VaR evaluation. The largest risks are modelled parametrically, while smaller risks are captured by

  14. Extreme value statistics in coupled lasers

    CERN Document Server

    Fridman, Moti; Nixon, Micha; Friesem, Asher A; Davidson, Nir

    2010-01-01

    Experimental configuration for investigating the dynamics and the statistics of the phase locking level of coupled lasers that have no common frequency is presented. The results reveal that the probability distribution of the phase locking level of such coupled lasers fits a Gumbel distribution that describes the extreme value statistic of Gaussian processes. A simple model, based on the spectral response of the coupled lasers, is also described, and the calculated results are in good agreement with the experimental results.

  15. An engineering primer on extreme value statistics

    Energy Technology Data Exchange (ETDEWEB)

    Novog, D.R.; Hoppe, F. [McMaster Univ., Hamilton, Ontario (Canada); Nainer, O. [Bruce Power, Tiverton, Ontario (Canada); Phan, B. [Ontario Power Generation, Toronto, Ontario (Canada)

    2009-07-01

    This primer is intended for individuals interested in gaining an understanding of Extreme Value Statistics (EVS). This work provides an explanation of EVS at a level that can be accessible to most people with an engineering or science background. While this work represents a simplification of the discussions from Reference 1, it is hoped that the authors will forgive any liberties taken in this paper. Some of the simplifications presented here may not be rigorous in all aspects, but the sacrifice in rigour is intended to aid the fundamental understanding of the EVS formulation and basic application. (author)

  16. Parallel computing, failure recovery, and extreme values

    DEFF Research Database (Denmark)

    Andersen, Lars Nørvang; Asmussen, Søren

    A task of random size T is split into M subtasks of lengths T1, . . . , TM, each of which is sent to one out of M parallel processors. Each processor may fail at a random time before completing its allocated task, and then has to restart it from the beginning. If X1, . . . ,XM are the total task...... times at the M processors, the overall total task time is then ZM = max1,...,MXi. Limit theorems as M → ∞ are given for ZM, allowing the distribution of T to depend on M. In some cases the limits are classical extreme value distributions, in others they are of a different type....

  17. Do decapod crustaceans have nociceptors for extreme pH?

    Directory of Open Access Journals (Sweden)

    Sakshi Puri

    Full Text Available BACKGROUND: Nociception is the physiological detection of noxious stimuli. Because of its obvious importance, nociception is expected to be widespread across animal taxa and to trigger robust behaviours reliably. Nociception in invertebrates, such as crustaceans, is poorly studied. METHODOLOGY/PRINCIPAL FINDINGS: THREE DECAPOD CRUSTACEAN SPECIES WERE TESTED FOR NOCICEPTIVE BEHAVIOUR: Louisiana red swamp crayfish (Procambarus clarkii, white shrimp (Litopenaeus setiferus, and grass shrimp (Palaemonetes sp.. Applying sodium hydroxide, hydrochloric acid, or benzocaine to the antennae caused no change in behaviour in the three species compared to controls. Animals did not groom the stimulated antenna, and there was no difference in movement of treated individuals and controls. Extracellular recordings of antennal nerves in P. clarkii revealed continual spontaneous activity, but no neurons that were reliably excited by the application of concentrated sodium hydroxide or hydrochloric acid. CONCLUSIONS/SIGNIFICANCE: Previously reported responses to extreme pH are either not consistently evoked across species or were mischaracterized as nociception. There was no behavioural or physiological evidence that the antennae contained specialized nociceptors that responded to pH.

  18. The Edgeworth expansion for distributions of extreme values

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We present necessary adn sufficient condition of Edgeworth expansion for drstribution sof extreme values As a corollart,artes of the uniform convergence ofr distribution s of extreme values are ovtained

  19. Kernel-type estimators for the extreme value index

    NARCIS (Netherlands)

    De Wolf, P.P.; Lopuhaa, H.P.; Groeneboom, P.

    2003-01-01

    A large part of the theory of extreme value index estimation is developed for positive extreme value indices. The best-known estimator of a positive extreme value index is probably the Hill estimator. This estimator belongs to the category of moment estimators, but can also be interpreted as a quasi

  20. Conference on Extreme Value Theory and Applications

    CERN Document Server

    Lechner, James; Simiu, Emil

    1994-01-01

    It appears that we live in an age of disasters: the mighty Missis­ sippi and Missouri flood millions of acres, earthquakes hit Tokyo and California, airplanes crash due to mechanical failure and the seemingly ever increasing wind speeds make the storms more and more frightening. While all these may seem to be unexpected phenomena to the man on the street, they are actually happening according to well defined rules of science known as extreme value theory. We know that records must be broken in the future, so if a flood design is based on the worst case of the past then we are not really prepared against floods. Materials will fail due to fatigue, so if the body of an aircraft looks fine to the naked eye, it might still suddenly fail if the aircraft has been in operation over an extended period of time. Our theory has by now penetrated the so­ cial sciences, the medical profession, economics and even astronomy. We believe that our field has come of age. In or~er to fully utilize the great progress in the the...

  1. Determination of the Ph &Turbidity Value in Betul Block Five Year

    Directory of Open Access Journals (Sweden)

    Ravi Kumar

    2016-07-01

    Full Text Available Acidic and basic are two extremes that describe chemicals, just like hot and cold are two extremes that describe temperature. Mixing acids and bases can cancel out their extreme effects; much like mixing hot and cold water can even out the water temperature. A substance that is neither acidic nor basic is neutral. The ph of the water in betul block is increasing year by year and day by day. It was observed that there are 0.5% increase in the ph of water in betul block. The optimum pH will vary in different supplies according to the composition of the water and the nature of the construction materials used in the distribution system, but is often in the range 6.5–9.5. Extreme pH values can result from accidental spills, treatment breakdowns, and insufficiently cured cement mortar pipe linings. No health-based guideline value is proposed for pH.

  2. A new fluorescent pH probe for extremely acidic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yu [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Jiang, Zheng [School of Life Science, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Xiao, Yu [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Bi, Fu-Zhen [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Miao, Jun-Ying, E-mail: miaojy@sdu.edu.cn [School of Life Science, Shandong University, Jinan 250100 (China); Zhao, Bao-Xiang, E-mail: bxzhao@sdu.edu.cn [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2014-04-01

    A new coumarin-based fluorescent probe can detect highly acidic conditions in both solution and bacteria with high selectivity and sensitivity. Highlights: • A new fluorescence probe for very low pH was synthesized and characterized. • The probe can monitor pH in solution and bacteria. • The two-step protonation of N atoms of the probe leads to fluorescence quenching. Abstract: A novel turn-off fluorescent probe based on coumarin and imidazole moiety for extremely acidic conditions was designed and developed. The probe with pKa = 2.1 is able to respond to very low pH value (below 3.5) with high sensitivity relying on fluorescence quenching at 460 nm in fluorescence spectra or the ratios of absorbance maximum at 380 nm to that at 450 nm in UV–vis spectra. It can quantitatively detect pH value based on equilibrium equation, pH = pKa -log[(Ix - Ib)/(Ia - Ix)]. It had very short response time that was less than 1 min, good reversibility and nearly no interference from common metal ions. Moreover, using ¹H NMR analysis and theoretical calculation of molecular orbital, we verified that a two-step protonation process of two N atoms of the probe leaded to photoinduced electron transfer (PET), which was actually the mechanism of the fluorescence quenching phenomenon under strongly acidic conditions. Furthermore, the probe was also applied to imaging strong acidity in bacteria, E.coli and had good effect. This work illustrates that the new probe could be a practical and ideal pH indicator for strongly acidic conditions with good biological significance.

  3. Ultimate 100m World Records Through Extreme-Value Theory

    NARCIS (Netherlands)

    Einmahl, J.H.J.; Smeets, S.G.W.R.

    2009-01-01

    We use extreme-value theory to estimate the ultimate world records for the 100m running, for both men and women. For this aim we collected the fastest personal best times set between January 1991 and June 2008. Estimators of the extreme-value index are based on a certain number of upper order

  4. Characterizations of bivariate conic, extreme value, and Archimax copulas

    Directory of Open Access Journals (Sweden)

    Saminger-Platz Susanne

    2017-01-01

    Full Text Available Based on a general construction method by means of bivariate ultramodular copulas we construct, for particular settings, special bivariate conic, extreme value, and Archimax copulas. We also show that the sets of copulas obtained in this way are dense in the sets of all conic, extreme value, and Archimax copulas, respectively.

  5. Extreme value theory and statistics for heavy tail data

    NARCIS (Netherlands)

    S. Caserta; C.G. de Vries (Casper)

    2003-01-01

    textabstractA scientific way of looking beyond the worst-case return is to employ statistical extreme value methods. Extreme Value Theory (EVT) shows that the probability on very large losses is eventually governed by a simple function, regardless the specific distribution that underlies the return

  6. Ultimate 100m World Records Through Extreme-Value Theory

    NARCIS (Netherlands)

    Einmahl, J.H.J.; Smeets, S.G.W.R.

    2009-01-01

    We use extreme-value theory to estimate the ultimate world records for the 100m running, for both men and women. For this aim we collected the fastest personal best times set between January 1991 and June 2008. Estimators of the extreme-value index are based on a certain number of upper order statis

  7. Ultimate 100m World Records Through Extreme-Value Theory

    NARCIS (Netherlands)

    Einmahl, J.H.J.; Smeets, S.G.W.R.

    2009-01-01

    We use extreme-value theory to estimate the ultimate world records for the 100m running, for both men and women. For this aim we collected the fastest personal best times set between January 1991 and June 2008. Estimators of the extreme-value index are based on a certain number of upper order statis

  8. Theory of multivariate compound extreme value distribution and its application to extreme sea state prediction

    Institute of Scientific and Technical Information of China (English)

    LIU Defu; WANG Liping; PANG Liang

    2006-01-01

    In this paper, a new type of distribution,multivariate compound extreme value distribution(MCEVD), is introduced by compounding a discrete distribution with a multivariate continuous distribution of extreme sea events. In its engineering application the number over certain threshold level per year is fitting to Poisson distribution and the corresponding extreme sea events are fitting to Nested Logistic distribution, then the Poisson-Nested logistic trivariate compound extreme value distribution (PNLTCED) is proposed to predict extreme wave heights, periods and wind speeds in Yellow Sea. The new model gives more stable and reasonable predicted results.

  9. Extremal values of the sojourn time

    Energy Technology Data Exchange (ETDEWEB)

    Astaburuaga, M A; Cortes, V H; Duclos, P, E-mail: angelica@mat.puc.c, E-mail: vcortes@mat.puc.c [Facultad de Matematicas, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago (Chile)

    2010-11-26

    Consider a self-adjoint operator H on a separable Hilbert space H with non-trivial absolutely continuous component. We study the general properties of the real-valued functional, {tau}{sub H}({psi})={integral}{sub R}|(e{sup -itH{psi}},{psi})|{sup 2} dt, which in quantum mechanics represents the sojourn time (or life time) of an initial state {psi} element of H. We characterize the critical points of the sojourn time, {tau}{sub X}, of the operator multiplication by x in L{sup 2}(R), and prove that it attains a global maximum in the unit sphere of the Sobolev space W{sup 1,2}(R).

  10. Analysis of Network Traffic with Extreme Value Theory

    Institute of Scientific and Technical Information of China (English)

    舒炎泰; 汪广洪; 高德云; 刘嘉焜; 王旭

    2003-01-01

    It is very important to analyze network traffic in the network control and management. In this paper,extreme value theory is first introduced and a model with threshold methods is proposed to analyze the characteristics of network traffic. In this model, only some traffic data that is greater than threshold value is considered.Then the proposed model with the trace is simulated by using S-Plus software. The modeling results show the network traffic model constructed from the extreme value theory fits well with that of empirical distribution. Finally, the extreme value model with the FARIMA(p,d,q) modeling is compared. The analytical results illustrate that extreme value theory has a good application foreground in the statistic analysis of network traffic. In addition, since only some traffic data which is greater than the threshold is processed, the computation overhead is reduced greatly.

  11. Ultimate 100m World Records Through Extreme-Value Theory

    OpenAIRE

    Einmahl, J.H.J.; Smeets, S.G.W.R.

    2009-01-01

    We use extreme-value theory to estimate the ultimate world records for the 100m running, for both men and women. For this aim we collected the fastest personal best times set between January 1991 and June 2008. Estimators of the extreme-value index are based on a certain number of upper order statistics. To optimize this number of order statistics we minimize the asymptotic mean squared error of the moment estimator. Using the thus obtained estimate for the extreme-value index, the right endp...

  12. Benthic fauna of extremely acidic lakes (pH 2-3)

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, G.G.

    2001-07-01

    The structure of the benthic invertebrate communities were investigated in terms of composition, abundance, and biomass from extremely acidic lakes with pH values from 2 to 3 in areas where coal was intensively mined in the Lusatian region in the eastern region of Germany. Benthic invertebrates colonisation on leaves and the breakdown rate processing of the three deciduous leaf: Betula pendula (birch), Fraxinus excelsior (ash), and Juglans regia (walnut) were investigated. Also, the main key-species of these acidic environments were investigated, in terms of description of pupal exuviae of Chironomus crassimanus and the feeding habit of this acid-resistant species through analysis of their gut content. The benthic food web in extremely acidic mining Lusatian lakes is very short in terms of species richness, trophic relationship, guilds and functional feeding groups. Collector-filters and scraper-grazers were absent in extremely acidic mining lakes (AML 107, AML 111 and AML 117). Shredders as Limnophyes minimus (Diptera, Chironomidae, Orthocladiinae) and Hydrozetes lacustris (Acari, Hydrozetidae) occurred in low abundance in AML 107 and AML 111, and it may be in response to slow leaf breakdown process in these ecosystems, except in AML 117 where the H. lacustris contributed most to ecosystems functioning via the processing of litter. Aquatic insects as Sialis lutaria (Megaloptera, Sialidae), Orectochilus villosus (Coleoptera, Gyrinidae), Coenagrion mercuriale (Odonata, Coenagrionidae), and Phryganeidae (Trichoptera) are the top-predators of these ecosystems. They did not depend on the level of pH in the lakes, but on the availability of food resources. (orig.)

  13. Estimation of Parameters of the Beta-Extreme Value Distribution

    Directory of Open Access Journals (Sweden)

    Zafar Iqbal

    2008-09-01

    Full Text Available In this research paper The Beta Extreme Value Type (III distribution which is developed by Zafar and Aleem (2007 is considered and parameters are estimated by using moments of the Beta-Extreme Value (Type III Distribution when the parameters ‘m’ & ‘n’ are real and moments of the Beta-Extreme Value (Type III Distribution when the parameters ‘m��� & ‘n’ are integers and then a Comparison between rth moments about origin when parameters are ‘m’ & ‘n’ are real and when parameters are ‘m’ & ‘n’ are integers. At the end second method, method of Maximum Likelihood is used to estimate the unknown parameters of the Beta Extreme Value Type (III distribution.

  14. extRemes 2.0: An Extreme Value Analysis Package in R

    Directory of Open Access Journals (Sweden)

    Eric Gilleland

    2016-08-01

    Full Text Available This article describes the extreme value analysis (EVA R package extRemes version 2.0, which is completely redesigned from previous versions. The functions primarily provide utilities for implementing univariate EVA, with a focus on weather and climate applications, including the incorporation of covariates, as well as some functionality for assessing bivariate tail dependence.

  15. Exchangeability, extreme returns and Value-at-Risk forecasts

    Science.gov (United States)

    Huang, Chun-Kai; North, Delia; Zewotir, Temesgen

    2017-07-01

    In this paper, we propose a new approach to extreme value modelling for the forecasting of Value-at-Risk (VaR). In particular, the block maxima and the peaks-over-threshold methods are generalised to exchangeable random sequences. This caters for the dependencies, such as serial autocorrelation, of financial returns observed empirically. In addition, this approach allows for parameter variations within each VaR estimation window. Empirical prior distributions of the extreme value parameters are attained by using resampling procedures. We compare the results of our VaR forecasts to that of the unconditional extreme value theory (EVT) approach and the conditional GARCH-EVT model for robust conclusions.

  16. Extreme value statistics for dynamical systems with noise

    CERN Document Server

    Faranda, Davide; Lucarini, Valerio; Turchetti, Giorgio; Vaienti, Sandro

    2012-01-01

    We study the distribution of maxima (Extreme Value Statistics) for sequences of observables computed along orbits generated by random transformations. The underlying, deterministic, dynamical system can be regular or chaotic. In the former case, we will show that by perturbing rational or irrational rotations with additive noise, an extreme value law will appear, regardless of the intensity of the noise, while unperturbed rotations do not admit such limiting distributions. In the case of deterministic chaotic dynamics, we will consider observables specially designed to study the recurrence properties in the neighbourhood of periodic points. The exponential limiting law for the distribution of maxima is therefore modified by the presence of the extremal index, a positive parameter not larger than one, whose inverse gives the average size of the clusters of extreme events. The theory predicts that such a parameter is unitary when the system is perturbed randomly. We perform sophisticated numerical tests to asse...

  17. EXTREME PROGRAMMING PROJECT PERFORMANCE MANAGEMENT BY STATISTICAL EARNED VALUE ANALYSIS

    OpenAIRE

    Wei Lu; Li Lu

    2013-01-01

    As an important project type of Agile Software Development, the performance evaluation and prediction for eXtreme Programming project has significant meanings. Targeting on the short release life cycle and concurrent multitask features, a statistical earned value analysis model is proposed. Based on the traditional concept of earned value analysis, the statistical earned value analysis model introduced Elastic Net regression function and Laplacian hierarchical model to construct a Bayesian El...

  18. Comparison of spatial extreme value models for snow depth extremes in Austria

    Science.gov (United States)

    Schellander, Harald; Hell, Tobias

    2017-04-01

    In Alpine regions like Austria a spatial representation of extreme snow depth is of crucial importance for numerous purposes such as the designing of construction projects. Extreme value theory builds the well-established foundation of modeling extremes. Two different approaches for the spatial modeling of snow depth extremes have been extensively investigated lately: Smooth Spatial Modeling (Blanchet and Lehning, 2010) and different classes of max-stable processes (Blanchet and Davison, 2011; Nicolet et al., 2015), both outperforming classical interpolation techniques. While max-stable models are generally considered as improvement over smooth modeling, the methods have not been compared in the context of extreme snow depth. In the present study a great variety of different GEV models is fitted to seasonal snow depth maxima measured at more than 200 Austrian weather stations. Return levels of smooth spatial models and several max-stable representations (Schlather, Brown-Resnick, Geometric Gaussian, Extremal-t) and covariance models (Powered Exponential, Brown, Whittle-Matern), also allowing for anisotropic extremal dependence are compared by a modified Anderson-Darling score and a normalized RMSE. Preliminary results show, that for snow depth extremes in Austria smooth spatial modeling and a version with extremal coefficients as covariates deliver slightly better scores than (an)-isotropic max-stable models.

  19. In situ measurements reveal extremely low pH in soil

    DEFF Research Database (Denmark)

    Nielsen, Knud Erik; Nielsen, Lars Peter; Damgaard, Christian Frølund

    2017-01-01

    We measured pH in situ in the top organic soil horizons in heathland and pine forest and found values between 2.6 and 3.2. This was 0.5e0.8 units lower than concurrent laboratory pH measurements of the same soil, which raises questions about the interpretation of pH measurements. We propose...... that the higher pH recorded by standard laboratory methods may be due to buffering ions from soil biota released from drying, grinding and rewetting of soil samples, whereas the in situ pH reflects the correct level of acidification....

  20. Extreme Values of Queues, Point Processes and Stochastic Networks.

    Science.gov (United States)

    2014-09-26

    AD-A158 619 EXTREMIE YALUES OF QUEUES POINT PROCESSES AND STOCHASTIC i/i NETUORKS(U) GEORGIA INST OF TECH ATLANTA R F SERFOZO 25 JUN 85 SFOSR-TR-85...O If "Extreme Values of Queues, Point Processes VW- and Stochastic Networks" 1 Grant No. AFOSR 84-0367 by Professor Richard F. Serfozo Industrial and...Claaraicajton) Extreme Values of Oueues. Point Processes & Stochastic Networks_ 12. PERSONAL AUTHOR(S) R_ F_ Serfozo 13. TYPE OF REPORT 13b. TIME COVERED 14

  1. Level density of a bose gas and extreme value statistics.

    Science.gov (United States)

    Comtet, A; Leboeuf, P; Majumdar, Satya N

    2007-02-16

    We establish a connection between the level density of a gas of noninteracting bosons and the theory of extreme value statistics. Depending on the exponent that characterizes the growth of the underlying single-particle spectrum, we show that at a given excitation energy the limiting distribution function for the number of excited particles follows the three universal distribution laws of extreme value statistics, namely, the Gumbel, Weibull, and Fréchet distributions. Implications of this result, as well as general properties of the level density at different energies, are discussed.

  2. Conformational changes in the bilirubin-human serum albumin complex at extreme alkaline pH

    DEFF Research Database (Denmark)

    Honoré, B; Frandsen, P C

    1986-01-01

    Light-absorption, c.d. and fluorescence of the bilirubin-albumin complex were investigated at extreme alkaline pH. Above pH 11.1 albumin binds the bilirubin molecule, twisted oppositely to the configuration at more neutral pH. On the basis of light-absorption it is shown that two alkaline...... transitions occur. The first alkaline transition takes place at pH between 11.3 and 11.8, co-operatively dissociating at least six protons. The second alkaline transition takes place at pH between 11.8 and 12.0. It probably implies a reversible unfolding of the albumin molecule, increasing the distance...

  3. The Edgeworth expansion for distributions of extreme values

    Institute of Scientific and Technical Information of China (English)

    CHENG; Shihong(

    2001-01-01

    [1] Gnedenko, B. V., Sur la distribution limite du terme maximum d'une serie aleatoire, Annals of Math., 1943, 44: 423.[2] de Haan, L., On regular variation and its application to the weak convergence of sample extreme, Math. Centre Tract 32, Amsterdam: Math. Centrum, 1970.[3] Hall, P., On the rate of convergence of normal extremes, J. Appl. Probab., 1979, 16: 433.[4] Hall, W. J., Wellner, J. A., The rate of convergence in law of the maximum of an exponential samples, Statist. Neerlandica, 1979, 33: 151.[5] Davis, R., The rate of convergence in distribution of the maxima, Statist. Neerlandica, 1982, 36: 31.[6] Smith, R., Uniform rates of convergence in extreme value theory, Adv. in Appl. Probab., 1982, 14: 543.[7] Resnick, S. I., Uniform rates of convergence to extreme value distribution, Probability and Statistis: Essays in Honor of Franklin Graybill, Amsterdam: North-Holland, 1986.[8] Resnick, S. I., Extreme Values, Regular variation, and Point Processes, New York: Springer, 1987.[9] de Haan, L., Resnick, S. I., Second order regular variation and rates of convergence in extreme value theory, Annals of Probab., 1996, 24: 97.[10] Geluk, J. L., de Haan, L., Regular variation, extensions and Tauberian theorems, CWI Tract 40, Amsterdam: Center for Mathematics and Computer Science, 1987.[11] de Haan, L., Stadtmuller, U., Generalized regular variation of second order, J. Austral. Math. Soc. Ser. A, 1998, 61: 381.[12] Omey, E., Willekens, E., Π-variation with remainder, J. London Math. Soc., 1988, 37: 105.[13] Vervaat, W., Functional central limit theorems for processes with positive drift and their inverses, Z. Wahrsch. Verw. Gebiete, 1972, 23: 249.

  4. AN ELIMINATION ALGORITHM OF EXTREME VALUES FOR INTEGRATED TRISPECTRUM

    Institute of Scientific and Technical Information of China (English)

    Liang Zongchuang; Liu Xingzhao; Liu Yongtan

    2002-01-01

    In this paper, an algorithm for eliminating extreme values and reducing the estimation variance of an integrated trispectrum under low signal-to-noise ratio and short data sample conditions is presented. An analysis of the results of simulations using this algorithm and comparison with the conventional power spectrum and integrated trispectrum methods are presented.

  5. Continuous Spatial Process Models for Spatial Extreme Values

    KAUST Repository

    Sang, Huiyan

    2010-01-28

    We propose a hierarchical modeling approach for explaining a collection of point-referenced extreme values. In particular, annual maxima over space and time are assumed to follow generalized extreme value (GEV) distributions, with parameters μ, σ, and ξ specified in the latent stage to reflect underlying spatio-temporal structure. The novelty here is that we relax the conditionally independence assumption in the first stage of the hierarchial model, an assumption which has been adopted in previous work. This assumption implies that realizations of the the surface of spatial maxima will be everywhere discontinuous. For many phenomena including, e. g., temperature and precipitation, this behavior is inappropriate. Instead, we offer a spatial process model for extreme values that provides mean square continuous realizations, where the behavior of the surface is driven by the spatial dependence which is unexplained under the latent spatio-temporal specification for the GEV parameters. In this sense, the first stage smoothing is viewed as fine scale or short range smoothing while the larger scale smoothing will be captured in the second stage of the modeling. In addition, as would be desired, we are able to implement spatial interpolation for extreme values based on this model. A simulation study and a study on actual annual maximum rainfall for a region in South Africa are used to illustrate the performance of the model. © 2009 International Biometric Society.

  6. An application of extreme value theory in estimating liquidity risk

    Directory of Open Access Journals (Sweden)

    Sonia Benito Muela

    2017-09-01

    Full Text Available The last global financial crisis (2007–2008 has highlighted the weaknesses of value at risk (VaR as a measure of market risk, as this metric by itself does not take liquidity risk into account. To address this problem, the academic literature has proposed incorporating liquidity risk into estimations of market risk by adding the VaR of the spread to the risk price. The parametric model is the standard approach used to estimate liquidity risk. As this approach does not generate reliable VaR estimates, we propose estimating liquidity risk using more sophisticated models based on extreme value theory (EVT. We find that the approach based on conditional extreme value theory outperforms the standard approach in terms of accurate VaR estimates and the market risk capital requirements of the Basel Capital Accord.

  7. Design of stability at extreme alkaline pH in streptococcal protein G.

    Science.gov (United States)

    Palmer, Benjamin; Angus, Katy; Taylor, Linda; Warwicker, Jim; Derrick, Jeremy P

    2008-04-30

    Protein G (PrtG) is widely used as an affinity-based ligand for the purification of IgG. It would be desirable to improve the resistance of affinity chromatography ligands, such as PrtG, to commercial cleaning-in-place procedures using caustic alkali (0.5 M NaOH). It has been shown that Asn residues are the most susceptible at extreme alkaline pH: here, we show that replacement of all three Asn residues within the IgG-binding domain of PrtG only improves stability towards caustic alkali by about 8-fold. Study of the effects of increasing pH on PrtG by fluorescence and CD shows that the protein unfolds progressively between pH 11.5 and 13.0. Calculation of the variation in electrostatic free energy with pH indicated that deprotonation of Tyr, Lys and Arg side-chains at high pH would destabilize PrtG. Introduction of the triple mutation Y3F/T16I/T18I into PrtG stabilized it by an extra 6.8 kcal/mol and the unfolding of the protein occurred at a pH of about 13, or 1.5 pH units higher than wild type. The results show that strategies for the stabilization of proteins at extreme alkaline pH should consider thermodynamic stabilization that will retain the tertiary structure of the protein and modification of surface electrostatics, as well as mutation of alkali-susceptible residues.

  8. Accounting for choice of measurement scale in extreme value modeling

    OpenAIRE

    Wadsworth, J. L.; Tawn, J. A.; Jonathan, P.

    2010-01-01

    We investigate the effect that the choice of measurement scale has upon inference and extrapolation in extreme value analysis. Separate analyses of variables from a single process on scales which are linked by a nonlinear transformation may lead to discrepant conclusions concerning the tail behavior of the process. We propose the use of a Box--Cox power transformation incorporated as part of the inference procedure to account parametrically for the uncertainty surrounding the scale of extrapo...

  9. Extreme values and kernel estimates of point processes boundaries

    CERN Document Server

    Girard, Stéphane

    2011-01-01

    We present a method for estimating the edge of a two-dimensional bounded set, given a finite random set of points drawn from the interior. The estimator is based both on a Parzen-Rosenblatt kernel and extreme values of point processes. We give conditions for various kinds of convergence and asymptotic normality. We propose a method of reducing the negative bias and edge effects, illustrated by a simulation.

  10. Extreme value statistics of weak lensing shear peak counts

    CERN Document Server

    Reischke, Robert; Bartelmann, Matthias

    2015-01-01

    The statistics of peaks in weak gravitational lensing maps is a promising technique to constrain cosmological parameters in present and future surveys. Here we investigate its power when using general extreme value statistics which is very sensitive to the exponential tail of the halo mass function. To this end, we use an analytic method to quantify the number of weak lensing peaks caused by galaxy clusters, large-scale structures and observational noise. Doing so, we further improve the method in the regime of high signal-to-noise ratios dominated by non-linear structures by accounting for the embedding of those counts into the surrounding shear caused by large scale structures. We derive the extreme value and order statistics for both over-densities (positive peaks) and under-densities (negative peaks) and provide an optimized criterion to split a wide field survey into sub-fields in order to sample the distribution of extreme values such that the expected objects causing the largest signals are mostly due ...

  11. Evaluation of dynamically downscaled extreme temperature using a spatially-aggregated generalized extreme value (GEV) model

    Science.gov (United States)

    Wang, Jiali; Han, Yuefeng; Stein, Michael L.; Kotamarthi, Veerabhadra R.; Huang, Whitney K.

    2016-11-01

    The weather research and forecast (WRF) model downscaling skill in extreme maximum daily temperature is evaluated by using the generalized extreme value (GEV) distribution. While the GEV distribution has been used extensively in climatology and meteorology for estimating probabilities of extreme events, accurately estimating GEV parameters based on data from a single pixel can be difficult, even with fairly long data records. This work proposes a simple method assuming that the shape parameter, the most difficult of the three parameters to estimate, does not vary over a relatively large region. This approach is applied to evaluate 31-year WRF-downscaled extreme maximum temperature through comparison with North American regional reanalysis (NARR) data. Uncertainty in GEV parameter estimates and the statistical significance in the differences of estimates between WRF and NARR are accounted for by conducting a novel bootstrap procedure that makes no assumption of temporal or spatial independence within a year, which is especially important for climate data. Despite certain biases over parts of the United States, overall, WRF shows good agreement with NARR in the spatial pattern and magnitudes of GEV parameter estimates. Both WRF and NARR show a significant increase in extreme maximum temperature over the southern Great Plains and southeastern United States in January and over the western United States in July. The GEV model shows clear benefits from the regionally constant shape parameter assumption, for example, leading to estimates of the location and scale parameters of the model that show coherent spatial patterns.

  12. Extreme value distribution and reliability of nonlinear stochastic structures

    Institute of Scientific and Technical Information of China (English)

    Chen Jianbing; Li Jie

    2005-01-01

    A new approach to evaluate the extreme value distribution (EVD) of the response and reliability of general multi-DOF nonlinear stochastic structures is proposed. The approach is based on the recently developed probability density evolution method, which enables the instantaneous probability density functions of the stochastic responses to be captured.In the proposed method, a virtual stochastic process is first constructed to satisfy the condition that the extreme value of the response equals the value of the constructed process at a certain instant of time. The probability density evolution method is then applied to evaluate the instantaneous probability density function of the response, yielding the EVD. The reliability is therefore available through a simple integration over the safe domain. A numerical algorithm is developed using the Number Theoretical Method to select the discretized representative points. Further, a hyper-ball is imposed to sieve the points from the preceding point set in the hypercube. In the numerical examples, the EVD of random variables is evaluated and compared with the analytical solution. A frame structure is analyzed to capture the EVD of the response and the dynamic reliability. The investigations indicate that the proposed approach provides reasonable accuracy and efficiency.

  13. THE MALAYSIA PM10 ANALYSIS USING EXTREME VALUE

    Directory of Open Access Journals (Sweden)

    HASFAZILAH AHMAT

    2015-12-01

    Full Text Available The study of air quality is closely associated to air pollution. Air pollution is of the main concerns of the authority in view of the fact that it can generate damaging effects to human health, crops and environment. This paper assesses the use of Extreme Value Distributions (EVD of the two-parameter Gumbel, two and three-parameter Weibull, Generalized Extreme Value (GEV and two and three-parameter Generalized Pareto Distribution (GPD on the maximum concentration of daily PM10 data recorded in the year 2010 - 2012 in Pasir Gudang, Johor, Bukit Rambai, Melaka and Nilai, Negeri Sembilan. Parameters for all distributions were estimated using the method of Maximum Likelihood Estimator (MLE. The goodness-of-fit of the distribution was determined using six performance indicators namely; the accuracy measures which include Prediction Accuracy (PA, Coefficient of Determination (R2, Index of Agreement (IA and error measures that consist of Root Mean Square Error (RMSE, Mean Absolute Error (MAE and Normalized Absolute Error (NAE. The best distribution was selected based on the highest accuracy measures which are close to 1 and the smallest error measures. The result showed that the Generalized Extreme Value (GEV distribution was the best fit for daily maximum concentration for PM10 for all monitoring stations. The GEV gave the smallest errors (NAE, RMSE and MAE and the highest accuracy measures (PA, R2 and IA when compared to other distributions. The method gave the accuracy of more than 98% in PA, IA and R2 for all stations. The analysis demonstrated that the estimated numbers of days in which the concentration of PM10 exceeded the Malaysian Ambient Air Quality Guidelines (MAAQG of 150 µg/m3 were between ½ and 2 days.

  14. Red Tide Frequency Analysis Using the Extreme Value Theory

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In recent years, the red tide erupted frequently, and caused a great economic loss. At present, most literatures emphasize the academic research on the growth mechanism of red tide alga. In order to find out the characters of red tide in detail and improve the precision of forecast, this paper gives some new approaches to dealing with the red tide. By the extreme values, we deal with the red tide frequency analysis and get the estimation of T-times red tide level U(T), which is the level once the consistence of red tide alga exceeds on the average in a period of T times.

  15. Generalized Extreme Value distribution parameters as dynamical indicators of Stability

    CERN Document Server

    Faranda, Davide; Turchetti, Giorgio; Vaienti, Sandro

    2011-01-01

    We introduce a new dynamical indicator of stability based on the Extreme Value statistics showing that it provides an insight on the local stability properties of dynamical systems. The indicator perform faster than other based on the iteration of the tangent map since it requires only the evolution of the original systems and, in the chaotic regions, gives further information about the information dimension of the attractor. A numerical validation of the method is presented through the analysis of the motions in a Standard map.

  16. Empirical Analysis of Value-at-Risk Estimation Methods Using Extreme Value Theory

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper investigates methods of value-at-risk (VaR) estimation using extreme value theory (EVT). Itcompares two different estimation methods, 。two-step subsample bootstrap" based on moment estimation and maximumlikelihood estimation (MLE), according to their theoretical bases and computation procedures. Then, the estimationresults are analyzed together with those of normal method and empirical method. The empirical research of foreignexchange data shows that the EVT methods have good characters in estimating VaR under extreme conditions and"two-step subsample bootstrap" method is preferable to MLE.

  17. Modeling extreme PM10 concentration in Malaysia using generalized extreme value distribution

    Science.gov (United States)

    Hasan, Husna; Mansor, Nadiah; Salleh, Nur Hanim Mohd

    2015-05-01

    Extreme PM10 concentration from the Air Pollutant Index (API) at thirteen monitoring stations in Malaysia is modeled using the Generalized Extreme Value (GEV) distribution. The data is blocked into monthly selection period. The Mann-Kendall (MK) test suggests a non-stationary model so two models are considered for the stations with trend. The likelihood ratio test is used to determine the best fitted model and the result shows that only two stations favor the non-stationary model (Model 2) while the other eleven stations favor stationary model (Model 1). The return level of PM10 concentration that is expected to exceed the maximum once within a selected period is obtained.

  18. A class of not max-stable extreme value distributions

    Institute of Scientific and Technical Information of China (English)

    JIANG Yue-xiang

    2005-01-01

    The sequences {Zi,n, l≤i≤n}, n≥l have multi-nomial distribution among i.i.d. random variables {X1,i, i≥1}, {X2,i,u≥l }, …, {Xm,i, i≥1 }. The extreme value distribution Gz(x) of this particular triangular array of i.i.d, random variables Z1,n, Z2Zn,n is discussed in this paper. We found a new type of not max-stable extreme value distributions, i) Gz(x) = r-1∏i=1ФAiαi(x) × Фαr (x);ii) Gz (x) = r-1∏i=1ψAiαi (x) × ψαr (x); iii) Gz (x) = r-1∏i=1 ∧Ai (λix) × A(x), r≥2, 0<α1≤α2≤…≤αr and λi∈ (0,1] for i, l≤i≤r-1 which occur if Fj, …, Fm belong to the same MDA.

  19. Extremely alkaline (pH > 12) ground water hosts diverse microbial community.

    Science.gov (United States)

    Roadcap, George S; Sanford, Robert A; Jin, Qusheng; Pardinas, José R; Bethke, Craig M

    2006-01-01

    Chemically unusual ground water can provide an environment for novel communities of bacteria to develop. Here, we describe a diverse microbial community that inhabits extremely alkaline (pH > 12) ground water from the Lake Calumet area of Chicago, Illinois, where historic dumping of steel slag has filled in a wetland. Using microbial 16S ribosomal ribonucleic acid gene sequencing and microcosm experiments, we confirmed the presence and growth of a variety of alkaliphilic beta-Proteobacteria, Bacillus, and Clostridium species at pH up to 13.2. Many of the bacterial sequences most closely matched those of other alkaliphiles found in more moderately alkaline water around the world. Oxidation of dihydrogen produced by reaction of water with steel slag is likely a primary energy source to the community. The widespread occurrence of iron-oxidizing bacteria suggests that reduced iron serves as an additional energy source. These results extend upward the known range of pH tolerance for a microbial community by as much as 2 pH units. The community may provide a source of novel microbes and enzymes that can be exploited under alkaline conditions.

  20. Influence of pH value on chromate-free conversion coating for magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    WENG Wen-ping; CHEN Qi; ZHANG Hui; ZHONG Hao; YAN Yun-qi

    2006-01-01

    Many factors were found to have effects on the conversion coatings for AZ31 alloy, alloy the most important one in producing high quality conversion coatings is found to be the control of the pH value. The influence of pH value on the conversion coating including color, thickness, adhesion and surface morphology was studied. The performance of conversion coating was examined by cross cut test, SEM method and salt immersion. The results show that the variation of pH value causes surface treatment process unstably. The conversion coating can obtain as pH value ranging from 3.0 to 5.0, while it presents dark, thick and bad adhesion under lower pH value. The conversion coatings have good combination of thickness and adhesion when pH value ranging from 4.0 to 4.5, and it exhibits a good corrosion resistance.

  1. A probabilistic analysis of wind gusts using extreme value statistics

    Energy Technology Data Exchange (ETDEWEB)

    Friederichs, Petra; Bentzien, Sabrina; Lenz, Anne; Krampitz, Rebekka [Meteorological Inst., Univ. of Bonn (Germany); Goeber, Martin [Deutscher Wetterdienst, Offenbach (Germany)

    2009-12-15

    The spatial variability of wind gusts is probably as large as that of precipitation, but the observational weather station network is much less dense. The lack of an area-wide observational analysis hampers the forecast verification of wind gust warnings. This article develops and compares several approaches to derive a probabilistic analysis of wind gusts for Germany. Such an analysis provides a probability that a wind gust exceeds a certain warning level. To that end we have 5 years of observations of hourly wind maxima at about 140 weather stations of the German weather service at our disposal. The approaches are based on linear statistical modeling using generalized linear models, extreme value theory and quantile regression. Warning level exceedance probabilities are estimated in response to predictor variables such as the observed mean wind or the operational analysis of the wind velocity at a height of 10 m above ground provided by the European Centre for Medium Range Weather Forecasts (ECMWF). The study shows that approaches that apply to the differences between the recorded wind gust and the mean wind perform better in terms of the Brier skill score (which measures the quality of a probability forecast) than those using the gust factor or the wind gusts only. The study points to the benefit from using extreme value theory as the most appropriate and theoretically consistent statistical model. The most informative predictors are the observed mean wind, but also the observed gust velocities recorded at the neighboring stations. Out of the predictors used from the ECMWF analysis, the wind velocity at 10 m above ground is the most informative predictor, whereas the wind shear and the vertical velocity provide no additional skill. For illustration the results for January 2007 and during the winter storm Kyrill are shown. (orig.)

  2. Prognosis of patients presenting extreme acidosis (pH <7) on admission to intensive care unit.

    Science.gov (United States)

    Allyn, Jérôme; Vandroux, David; Jabot, Julien; Brulliard, Caroline; Galliot, Richard; Tabatchnik, Xavier; Combe, Patrice; Martinet, Olivier; Allou, Nicolas

    2016-02-01

    The purpose was to determine prognosis of patients presenting extreme acidosis (pH acidosis within 24 hours of admission to a polyvalent ICU in a university hospital between January 2011 and July 2013. Multivariate analysis and survival analysis were used. Among the 2156 patients admitted, 77 patients (3.6%) presented extreme acidosis. Thirty (39%) patients suffered cardiac arrest before admission. Although the mortality rate predicted by severity score was 93.6%, death occurred in 52 cases (67.5%) in a median delay of 13 (5-27) hours. Mortality rate depended on reason for admission, varying between 22% for cases linked to diabetes mellitus and 100% for cases of mesenteric infarction (P = .002), cardiac arrest before admission (P acidosis (P = .007), high Simplified Acute Physiology Score II (P = .008), and low serum creatinine (P = .012). Patients with extreme acidosis on admission to ICU have a less severe than expected prognosis. Whereas mortality is almost 100% in cases of cardiac arrest before admission, mortality is much lower in the absence of cardiac arrest before admission, which justifies aggressive ICU therapies. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Extreme value statistics and thermodynamics of earthquakes: large earthquakes

    Directory of Open Access Journals (Sweden)

    B. H. Lavenda

    2000-06-01

    Full Text Available A compound Poisson process is used to derive a new shape parameter which can be used to discriminate between large earthquakes and aftershock sequences. Sample exceedance distributions of large earthquakes are fitted to the Pareto tail and the actual distribution of the maximum to the Fréchet distribution, while the sample distribution of aftershocks are fitted to a Beta distribution and the distribution of the minimum to the Weibull distribution for the smallest value. The transition between initial sample distributions and asymptotic extreme value distributions shows that self-similar power laws are transformed into nonscaling exponential distributions so that neither self-similarity nor the Gutenberg-Richter law can be considered universal. The energy-magnitude transformation converts the Fréchet distribution into the Gumbel distribution, originally proposed by Epstein and Lomnitz, and not the Gompertz distribution as in the Lomnitz-Adler and Lomnitz generalization of the Gutenberg-Richter law. Numerical comparison is made with the Lomnitz-Adler and Lomnitz analysis using the same Catalogue of Chinese Earthquakes. An analogy is drawn between large earthquakes and high energy particle physics. A generalized equation of state is used to transform the Gamma density into the order-statistic Fréchet distribution. Earthquaketemperature and volume are determined as functions of the energy. Large insurance claims based on the Pareto distribution, which does not have a right endpoint, show why there cannot be a maximum earthquake energy.

  4. Extreme value statistics and thermodynamics of earthquakes. Large earthquakes

    Energy Technology Data Exchange (ETDEWEB)

    Lavenda, B. [Camerino Univ., Camerino, MC (Italy); Cipollone, E. [ENEA, Centro Ricerche Casaccia, S. Maria di Galeria, RM (Italy). National Centre for Research on Thermodynamics

    2000-06-01

    A compound Poisson process is used to derive a new shape parameter which can be used to discriminate between large earthquakes and aftershocks sequences. Sample exceedance distributions of large earthquakes are fitted to the Pareto tail and the actual distribution of the maximum to the Frechet distribution, while the sample distribution of aftershocks are fitted to a Beta distribution and the distribution of the minimum to the Weibull distribution for the smallest value. The transition between initial sample distributions and asymptotic extreme value distributions show that self-similar power laws are transformed into non scaling exponential distributions so that neither self-similarity nor the Gutenberg-Richter law can be considered universal. The energy-magnitude transformation converts the Frechet distribution into the Gumbel distribution, originally proposed by Epstein and Lomnitz, and not the Gompertz distribution as in the Lomnitz-Adler and Lomnitz generalization of the Gutenberg-Richter law. Numerical comparison is made with the Lomnitz-Adler and Lomnitz analysis using the same catalogue of Chinese earthquakes. An analogy is drawn between large earthquakes and high energy particle physics. A generalized equation of state is used to transform the Gamma density into the order-statistic Frechet distribution. Earthquake temperature and volume are determined as functions of the energy. Large insurance claims based on the Pareto distribution, which does not have a right endpoint, show why there cannot be a maximum earthquake energy.

  5. Development of plotting position for the general extreme value distribution

    Science.gov (United States)

    Kim, Sooyoung; Shin, Hongjoon; Joo, Kyoungwon; Heo, Jun-Haeng

    2012-12-01

    SummaryProbability plotting positions are used to graphically display the annual maximum rainfall or flood and to estimate the exceedance probabilities of those values. Therefore, the graphical approach using plotting positions has been applied in many hydrology and water resource engineering fields. The definition of unbiased plotting positions by Cunnane (1978) as the mean of the order statistics from reduced variates has influenced researchers to develop the plotting position of the probability distribution containing shape parameters. In this study, the plotting position formula for the general extreme value (GEV) distribution was derived by using the theoretical reduced variates of the GEV distribution for various sample sizes and shape parameters. To choose an appropriate plotting position formula, we examined eight plotting position formula types containing coefficients of skewness or squared coefficients of skewness in the numerator and/or denominator. In addition, the parameters of the plotting position formula for the GEV distribution were estimated by using a genetic optimization method known as the real-coded genetic algorithm (RGA). The accuracy of the derived plotting position formula for the GEV distribution was examined on the basis of the root mean square errors and relative bias between the theoretical reduced variates and those calculated from the derived and existing plotting position formulas. The derived plotting formula was found to be useful if the range of the shape parameter was within ±0.2.

  6. Modeling Source Water Threshold Exceedances with Extreme Value Theory

    Science.gov (United States)

    Rajagopalan, B.; Samson, C.; Summers, R. S.

    2016-12-01

    Variability in surface water quality, influenced by seasonal and long-term climate changes, can impact drinking water quality and treatment. In particular, temperature and precipitation can impact surface water quality directly or through their influence on streamflow and dilution capacity. Furthermore, they also impact land surface factors, such as soil moisture and vegetation, which can in turn affect surface water quality, in particular, levels of organic matter in surface waters which are of concern. All of these will be exacerbated by anthropogenic climate change. While some source water quality parameters, particularly Total Organic Carbon (TOC) and bromide concentrations, are not directly regulated for drinking water, these parameters are precursors to the formation of disinfection byproducts (DBPs), which are regulated in drinking water distribution systems. These DBPs form when a disinfectant, added to the water to protect public health against microbial pathogens, most commonly chlorine, reacts with dissolved organic matter (DOM), measured as TOC or dissolved organic carbon (DOC), and inorganic precursor materials, such as bromide. Therefore, understanding and modeling the extremes of TOC and Bromide concentrations is of critical interest for drinking water utilities. In this study we develop nonstationary extreme value analysis models for threshold exceedances of source water quality parameters, specifically TOC and bromide concentrations. In this, the threshold exceedances are modeled as Generalized Pareto Distribution (GPD) whose parameters vary as a function of climate and land surface variables - thus, enabling to capture the temporal nonstationarity. We apply these to model threshold exceedance of source water TOC and bromide concentrations at two locations with different climate and find very good performance.

  7. PH Value" Design Show Unveils the Shanghai Dream%"PH Value" Design Show Unveils the Shanghai Dream

    Institute of Scientific and Technical Information of China (English)

    Wanzy Wang

    2012-01-01

    "PH Value" Design Show, organized by China National Textile and Apparel Council (CNTAC), undertaken by the Sub- Council of Textile Industry, CCPIT (CCPIT-TEX), China Knitting industry Association, and China National Garment Association (CNGA), will be held from October 22rid to 23rd in Shanghai, unveiling the charming mysteries of "Shanghai Dream".

  8. Low medium pH value enhances anthocyanin accumulation in Malus crabapple leaves.

    Directory of Open Access Journals (Sweden)

    Yanchen Zhang

    Full Text Available Anthocyanin is a critical factor involved in coloration of plant tissues, but the mechanism how medium pH values affect anthocyanin accumulation in woody plants is unknown. We analyzed anthocyanin composition and the expression of elements encoding anthocyanin and flavonols biosynthesis underlying different medium pH values by using three different leave color type cultivars. HPLC analysis demonstrated that high medium pH values treatment induced a dramatic decrease in the concentration of cyaniding in crabapple leaves. Conversely, the high medium pH values induced up-regulation of the content of flavones and flavonols, suggesting that low pH treatment-induced anthocyanin accumulation. Quantitative real time PCR experiment showed the expression level of anthocyanidin synthase (McANS and uridine diphosphate glucose flavonoid 3-O-glucosyltransferase (McUFGT was up-regulated by low pH values treatment, and high medium pH value treatment up-regulate the transcription level of flavonol synthase (McFLS. Meanwhile, several MYB TFs have been suggested in the regulation of pH responses. These results strongly indicate that the low pH treatment-induced anthocyanin accumulation is mediated by the variation of mRNA transcription of the anthocyanin biosynthetic genes.

  9. Photoionization of aromatic amino acid at different pH values

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The photoioization of aromatic amino acid in solutions of different pH values were investigated by 248 nm laser flash photolysis. The results showed that the photoionizations of tyrosine and tryptophan were affected by pH value of solution, but phenylalanine was not. The ionization was in favor of monophotonic process at high pH value and of biphotonic process at low pH value. The mechanisms of pH effect on photoionization of tyrosine and tryptophan were the deprotonation of phenolic hydroxyl group and the deprotonation of>NH on the indole ring respectively. Our results explain the discrepancy of values for the yield of hydrated electron obtained by other investigators.

  10. Appropriate model selection methods for nonstationary generalized extreme value models

    Science.gov (United States)

    Kim, Hanbeen; Kim, Sooyoung; Shin, Hongjoon; Heo, Jun-Haeng

    2017-04-01

    Several evidences of hydrologic data series being nonstationary in nature have been found to date. This has resulted in the conduct of many studies in the area of nonstationary frequency analysis. Nonstationary probability distribution models involve parameters that vary over time. Therefore, it is not a straightforward process to apply conventional goodness-of-fit tests to the selection of an appropriate nonstationary probability distribution model. Tests that are generally recommended for such a selection include the Akaike's information criterion (AIC), corrected Akaike's information criterion (AICc), Bayesian information criterion (BIC), and likelihood ratio test (LRT). In this study, the Monte Carlo simulation was performed to compare the performances of these four tests, with regard to nonstationary as well as stationary generalized extreme value (GEV) distributions. Proper model selection ratios and sample sizes were taken into account to evaluate the performances of all the four tests. The BIC demonstrated the best performance with regard to stationary GEV models. In case of nonstationary GEV models, the AIC proved to be better than the other three methods, when relatively small sample sizes were considered. With larger sample sizes, the AIC, BIC, and LRT presented the best performances for GEV models which have nonstationary location and/or scale parameters, respectively. Simulation results were then evaluated by applying all four tests to annual maximum rainfall data of selected sites, as observed by the Korea Meteorological Administration.

  11. Measurement of individual intracellular pH and membrane potential values in living cells

    Science.gov (United States)

    Slavik, Jan; Lanz, Edvard; Cimprich, Petr

    1999-07-01

    It was assumed that each cell is a homogeneous suspension may have a slightly different pH and membrane potential. A wide range of pH-sensitive fluorescent dyes BCECF, SNARF, FITC, carboxyfluorescein, fluorescein and pyranine have been carefully tested for the accuracy and reliability of their pH-response inside living cells. The intracellular milieu was simulated by a series of mineral buffers with addition of proteins. The pH values have been determined from the excitation ratios 490/435 nm for BCECF, FITC, carboxyfluorescein and fluorescein, and 450/400 nm for pyranine, emission ratios 518/529 nm for BCECF and 635/590 nm for SNARF. The spectrally determined values were then compared with the pH values of buffers measured by a glass electrode. Using the data from the calibration procedure, we evaluated individual intracellular pH values of a large number of cells within one cell population. The confocal ratio fluorescence microscopy revealed pH maps from which both cytoplasmic and vacuolar pH values could be determine, flow cytometry gave enormous amount of average intracellular pH values of individual cells of a whole cell population. Each cell population exhibited significant differences in both cytoplasmic pH values among individual cells. The pH distribution of a typical cell population appeared to fit a Gaussian curve. In yeast it was a Gaussian curve with half- width values around 0.4 pH unit. The men pH values depended on the growth phase, H-ATPase activity and external pH values. The preliminary result with the new membrane potential dye tetramethylrhodamine methyl ester indicated that similarly to pH values, there is a heterogeneity in membrane potential values among cell sin one cell population. The data presented above suggest that each ell behaves as an individual with an individual set up of its metabolism. This 'fine tuning' of the metabolism result in slightly higher or lower pH or membrane potential values that can be detected by fluorescence

  12. Mapping the hazard of extreme rainfall by peaks-over-threshold extreme value analysis and spatial regression techniques

    NARCIS (Netherlands)

    Beguería, S.; Vicente-Serrano, S.M.

    2006-01-01

    The occurrence of rainfalls of high magnitude constitutes a primary natural hazard in many parts of the world, and the elaboration of maps showing the hazard of extreme rainfalls has great theoretical and practical interest. In this work a procedure based on extreme value analysis and spatial

  13. Yogurt made from milk heated at different pH values.

    Science.gov (United States)

    Ozcan, Tulay; Horne, David S; Lucey, John A

    2015-10-01

    Milk for yogurt manufacture is subjected to high heat treatment to denature whey proteins. Low milk pH values (≤ 6.5) at heating result in most denatured whey proteins becoming associated with casein micelles, whereas high milk pH values (≥ 7.0) at heating result in the formation of mostly soluble (nonmicellar) denatured whey protein complexes. There are conflicting reports on the relative importance of soluble and casein-bound whey protein aggregates on the properties of acid gels. Prior studies investigating the effect of pH of milk at heating used model gels in which milk was acidified by glucono-δ-lactone; in this study, we prepared yogurt gels using commercial starter cultures. Model acid gels can have very different texture and physical properties from those made by fermentation with starter cultures. In this study, we investigated the effects of different pH values of milk at heating on the rheological, light backscatter, and microstructural properties of yogurt gels. Reconstituted skim milk was adjusted to pH values 6.2, 6.7, and 7.2 and heated at 85°C for 30 min. A portion of the heated milk samples was readjusted back to pH 6.7 after heating. Milks were inoculated with 3% (wt/wt) yogurt starter culture and incubated at 40°C until pH 4.6. Gel formation was monitored using dynamic oscillatory rheology, and parameters measured included the storage modulus (G') and loss tangent (LT) values. Light-backscattering properties, such as the backscatter ratio (R) and the first derivative of light backscatter ratio (R'), were also monitored during fermentation. Fluorescence microscopy was used to observe gel microstructure. The G' values at pH 4.6 were highest in gels made from milk heated at pH 6.7 and lowest in milk heated at pH 6.2, with or without pH adjustment after heating. The G' values at pH 4.6 were lower in samples after adjustment back to pH 6.7 after heating. No maximum in the LT parameter was observed during gelation for yogurts made from milk

  14. Value-at-risk estimation with wavelet-based extreme value theory: Evidence from emerging markets

    Science.gov (United States)

    Cifter, Atilla

    2011-06-01

    This paper introduces wavelet-based extreme value theory (EVT) for univariate value-at-risk estimation. Wavelets and EVT are combined for volatility forecasting to estimate a hybrid model. In the first stage, wavelets are used as a threshold in generalized Pareto distribution, and in the second stage, EVT is applied with a wavelet-based threshold. This new model is applied to two major emerging stock markets: the Istanbul Stock Exchange (ISE) and the Budapest Stock Exchange (BUX). The relative performance of wavelet-based EVT is benchmarked against the Riskmetrics-EWMA, ARMA-GARCH, generalized Pareto distribution, and conditional generalized Pareto distribution models. The empirical results show that the wavelet-based extreme value theory increases predictive performance of financial forecasting according to number of violations and tail-loss tests. The superior forecasting performance of the wavelet-based EVT model is also consistent with Basel II requirements, and this new model can be used by financial institutions as well.

  15. The pH Value of Fungicide, Insecticide and Mineral Fertilizer Mixtures Depending on Water Quality

    Directory of Open Access Journals (Sweden)

    Dušanka Inđić

    2008-01-01

    Full Text Available The paper deals with the effect of water quality on the pH value of fungicides, insecticides, mineral fertilizers and their mixtures. The fungicides propineb (Antracol WP-70 and mancozeb (Dithane M-70, insecticides pirimiphos-methyl (Actellic-50 and imidacloprid(Confidor 200-SL, several fertilizers (Ferticare I, Ferticare II, Ferticare III and Wuxal Super and their mixtures were analyzed for pH value under laboratory conditions using a potentiometric pH meter. Measurements were made directly after preparation or mixing with tap and well water and 24 hours later. Tap water exhibited a neutral reaction. A slightly alkaline reaction of well water was mostlikely due to high ammonium content. The suspensions of Antracol WP-70 exhibited slightly alkaline reactions with both water types during 24 hours. The spray liquids of Dithane M-70 mixed with tap or well water had neutral reaction after preparation and slightly alkaline reaction after 24 hours. The emulsions of Actellic-50 showed neutral reaction with both water types, followed by a pH increase in tap water after 24 hours. The solutions of Confidor200-SL had a slightly alkaline reaction after mixing and the pH value increased with both water types after 24 hours. It is therefore recommended to apply these insecticides directly after preparation. Mineral fertilizers considerably reduced pH values of the fungicide and insecticide components in double and triple mixtures, especially Ferticare nutrients which had a moderately acid reaction. Wuxal Super had a neutral reaction with both water types.The mixtures with well water increased pH values, which indicates that water pH does affect the pH value of the mixture. Both individual fertilizers and all mixtures (double and triple with Ferticare had pH values between 2.4 and 6, which allows their active liquids to be stored for 12 to 24 hours. The suspensions (Antracol WP-70, double and triple mixtures, emulsions (Actellic-50 and Actellic-50+Wuxal Super

  16. Independent test assessment using the extreme value distribution theory.

    Science.gov (United States)

    Almeida, Marcio; Blondell, Lucy; Peralta, Juan M; Kent, Jack W; Jun, Goo; Teslovich, Tanya M; Fuchsberger, Christian; Wood, Andrew R; Manning, Alisa K; Frayling, Timothy M; Cingolani, Pablo E; Sladek, Robert; Dyer, Thomas D; Abecasis, Goncalo; Duggirala, Ravindranath; Blangero, John

    2016-01-01

    The new generation of whole genome sequencing platforms offers great possibilities and challenges for dissecting the genetic basis of complex traits. With a very high number of sequence variants, a naïve multiple hypothesis threshold correction hinders the identification of reliable associations by the overreduction of statistical power. In this report, we examine 2 alternative approaches to improve the statistical power of a whole genome association study to detect reliable genetic associations. The approaches were tested using the Genetic Analysis Workshop 19 (GAW19) whole genome sequencing data. The first tested method estimates the real number of effective independent tests actually being performed in whole genome association project by the use of an extreme value distribution and a set of phenotype simulations. Given the familiar nature of the GAW19 data and the finite number of pedigree founders in the sample, the number of correlations between genotypes is greater than in a set of unrelated samples. Using our procedure, we estimate that the effective number represents only 15 % of the total number of independent tests performed. However, even using this corrected significance threshold, no genome-wide significant association could be detected for systolic and diastolic blood pressure traits. The second approach implements a biological relevance-driven hypothesis tested by exploiting prior computational predictions on the effect of nonsynonymous genetic variants detected in a whole genome sequencing association study. This guided testing approach was able to identify 2 promising single-nucleotide polymorphisms (SNPs), 1 for each trait, targeting biologically relevant genes that could help shed light on the genesis of the human hypertension. The first gene, PFH14, associated with systolic blood pressure, interacts directly with genes involved in calcium-channel formation and the second gene, MAP4, encodes a microtubule-associated protein and had already been

  17. Records in Athletics through Extreme-Value Theory

    NARCIS (Netherlands)

    Einmahl, J.H.J.; Magnus, J.R.

    2006-01-01

    In this paper we shall be interested in two questions on extremes relating to world records in athletics.The first question is: what is the ultimate world record in a specific athletics event (such as the 100m for men or the high jump for women), given today's state of the art?Our second question is

  18. Records in Athletics through Extreme-Value Theory

    NARCIS (Netherlands)

    Einmahl, J.H.J.; Magnus, J.R.

    2006-01-01

    In this paper we shall be interested in two questions on extremes relating to world records in athletics.The first question is: what is the ultimate world record in a specific athletics event (such as the 100m for men or the high jump for women), given today's state of the art?Our second question

  19. Dependence of Nanofluid Viscosity on Particle Size and pH Value

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jia-Fei; LUO Zhong-Yang; NI Ming-Jiang; CEN Ke-Fa

    2009-01-01

    We investigate the viscosity of silicon dioxide nanofluid at different particle sizes and pH values considering nanoparticle aggregation.The experimental and simulation results indicate that nanoparticle size is of crucial importance to the viscosity of the nanofluid due to aggregation.As the nanoparticle size decreases,the viscosity becomes much more dependent on the volume fraction.Moreover,when the nanoparticle diameter is smaller than 20 rim,the viscosity is closely related to the pH of the nanofluid,and fluctuates with pH values from 5 and 7.

  20. Charge-transfer-based terbium MOF nanoparticles as fluorescent pH sensor for extreme acidity.

    Science.gov (United States)

    Qi, Zewan; Chen, Yang

    2017-01-15

    Newly emerged metal organic frameworks (MOFs) have aroused the great interest in designing functional materials by means of its flexible structure and component. In this study, we used lanthanide Tb(3+) ions and small molecular ligands to design and assemble a kind of pH-sensitive MOF nanoparticle based on intramolecular-charge-transfer effect. This kind of made-to-order MOF nanoparticle for H(+) is highly specific and sensitive and could be used to fluorescently indicate pH value of strong acidic solution via preset mechanism through luminescence of Tb(3+). The long luminescence lifetime of Tb(3+) allows eliminating concomitant non-specific fluorescence by time-revised fluorescence techniques, processing an advantage in sensing H(+) in biological media with strong autofluorescence. Our method showed a great potential of MOF structures in designing and constructing sensitive sensing materials for specific analytes directly via the assembly of functional ions/ligands.

  1. Macroinvertebrate and algal communities in an extremely acidic river and the Kawah Ijen crater lake (pH

    NARCIS (Netherlands)

    Löhr, A.J.; Sluik, R.; Olaveson, M.M.; Ivorra, N.; van Gestel, C.A.M.; van Straalen, N.M.

    2006-01-01

    Acidic aquatic ecosystems are mainly characterized by low pH and high concentrations of metals and other elements with evident effects on local community structure. Acidity effects on benthic communities in one of the world's largest extremely acidic crater lakes, the Kawah Ijen (East Java, Indonesi

  2. Macroinvertebrate and algal communities in an extremely acidic river and the Kawah Ijen crater lake (pH

    NARCIS (Netherlands)

    Löhr, A.J.; Sluik, R.; Olaveson, M.M.; Ivorra, N.; van Gestel, C.A.M.; van Straalen, N.M.

    2006-01-01

    Acidic aquatic ecosystems are mainly characterized by low pH and high concentrations of metals and other elements with evident effects on local community structure. Acidity effects on benthic communities in one of the world's largest extremely acidic crater lakes, the Kawah Ijen (East Java,

  3. Extreme Value Theory and Value at Risk. Application to oil market

    Energy Technology Data Exchange (ETDEWEB)

    Marimoutou, Velayoudoum [GREQAM, Universite de la Mediterranee, Institut Francais de Pondichery (France); Raggad, Bechir; Trabelsi, Abdelwahed [BESTMOD, Institut Superieur de Gestion de Tunis (Tunisia)

    2009-07-15

    Recent increases in energy prices, especially oil prices, have become a principal concern for consumers, corporations, and governments. Most analysts believe that oil price fluctuations have considerable consequences on economic activity. Oil markets have become relatively free, resulting in a high degree of oil-price volatility and generating radical changes to world energy and oil industries. Consequently, oil markets are naturally vulnerable to significant high price shifts. An example of such a case is the oil embargo crisis of 1973. In this newly created climate, protection against market risk has become a necessity. Value at Risk (VaR) measures risk exposure at a given probability level and is very important for risk management. Appealing aspects of Extreme Value Theory (EVT) have made convincing arguments for its use in managing energy price risks. In this paper, we model VaR for long and short trading positions in oil market by applying both unconditional and conditional EVT models to forecast Value at Risk. These models are compared to the performances of other well-known modelling techniques, such as GARCH, Historical Simulation and Filtered Historical Simulation. Both conditional EVT and Filtered Historical Simulation procedures offer a major improvement over the conventional methods. Furthermore, GARCH(1, 1)-t model may provide equally good results which are comparable to two combined procedures. Finally, our results confirm the importance of filtering process for the success of standard approaches. (author)

  4. Traumatic extremity arterial injury in children: Epidemiology, diagnostics, treatment and prognostic value of Mangled Extremity Severity Score

    OpenAIRE

    Lange Nadine; Khaladj Nawid; Frink Michael; Hildebrand Frank; Zeckey Christian; Mommsen Philipp; Krettek Christian; Probst Christian

    2010-01-01

    Abstract Background Traumatic paediatric arterial injuries are a great challenge due to low incidence and specific characteristics of paediatric anatomy and physiology. The aim of the present study was to investigate their epidemiology, diagnostic and therapeutic options and complications. Furthermore, the prognostic value of the Mangled Extremity Severity Score (MESS) was evaluated. Methods In a retrospective clinical study 44 children aged 9.0 ± 3.2 years treated for traumatic extremity art...

  5. Redox transformations of iron at extremely low pH: fundamental and applied aspects

    Directory of Open Access Journals (Sweden)

    D. Barrie eJohnson

    2012-03-01

    Full Text Available Many different species of acidophilic prokaryotes, widely distributed within the domains Bacteria and Archaea, can catalyze the dissimilatory oxidation of ferrous iron or reduction of ferric iron, or can do both. Microbially-mediated cycling of iron in extremely acidic environments (pH <3 is strongly influenced by the enhanced chemical stability of ferrous iron and far greater solubility of ferric iron under such conditions. Cycling of iron has been demonstrated in vitro using both pure and mixed cultures of acidophiles, and there is considerable evidence that active cycling of iron occurs in acid mine drainage streams, pit lakes and iron-rich acidic rivers, such as the Rio Tinto. Measurements of specific rates of iron oxidation and reduction by acidophilic microorganisms show that different species vary in their capacities for iron oxido-reduction, and that this is influenced by the electron donor provided and growth conditions used. These measurements, and comparison with corresponding data for oxidation of reduced sulfur compounds, also help explain why ferrous iron is usually used preferentially as an electron donor by acidophiles that can oxidize both iron and sulfur, even though the energy yield from oxidizing iron is much smaller than that available from sulfur oxidation. Iron-oxidizing acidophiles have been used in biomining (a technology that harness their abilities to accelerate the oxidative dissolution of sulfidic minerals and thereby facilitate the extraction of precious and base metals for several decades. More recently they have also been used to simultaneously remediate iron-contaminated surface and ground-waters and produce a useful mineral by-product (schwertmannite. Bioprocessing of oxidized mineral ores using acidophiles that bring about the reductive dissolution of ferric iron minerals such as goethite has also recently been demonstrated, and new biomining technologies based on this approach are being developed.

  6. Estimating changes in temperature extremes from millennial-scale climate simulations using generalized extreme value (GEV) distributions

    Science.gov (United States)

    Huang, Whitney K.; Stein, Michael L.; McInerney, David J.; Sun, Shanshan; Moyer, Elisabeth J.

    2016-07-01

    Changes in extreme weather may produce some of the largest societal impacts of anthropogenic climate change. However, it is intrinsically difficult to estimate changes in extreme events from the short observational record. In this work we use millennial runs from the Community Climate System Model version 3 (CCSM3) in equilibrated pre-industrial and possible future (700 and 1400 ppm CO2) conditions to examine both how extremes change in this model and how well these changes can be estimated as a function of run length. We estimate changes to distributions of future temperature extremes (annual minima and annual maxima) in the contiguous United States by fitting generalized extreme value (GEV) distributions. Using 1000-year pre-industrial and future time series, we show that warm extremes largely change in accordance with mean shifts in the distribution of summertime temperatures. Cold extremes warm more than mean shifts in the distribution of wintertime temperatures, but changes in GEV location parameters are generally well explained by the combination of mean shifts and reduced wintertime temperature variability. For cold extremes at inland locations, return levels at long recurrence intervals show additional effects related to changes in the spread and shape of GEV distributions. We then examine uncertainties that result from using shorter model runs. In theory, the GEV distribution can allow prediction of infrequent events using time series shorter than the recurrence interval of those events. To investigate how well this approach works in practice, we estimate 20-, 50-, and 100-year extreme events using segments of varying lengths. We find that even using GEV distributions, time series of comparable or shorter length than the return period of interest can lead to very poor estimates. These results suggest caution when attempting to use short observational time series or model runs to infer infrequent extremes.

  7. THE IMPACT OF CONJUGATED LINOLEIC ACID ADDITION ON PH VALUE OF LONGISSIMUS DORSI MUSCLE

    Directory of Open Access Journals (Sweden)

    Przemysław WASILEWSKI

    2009-08-01

    Full Text Available The subject of research was 60 crossbred gilts, divided into 6 groups, fed the fodder with addition of conjugated linoleic acid (CLA or sunflower oil (SFO in amount: 0.5; 1.0; and 2.0 %, respectively. Animals were slaughtered with the body weight ca. 95 kg. The aim of research was to determine pH value of loin meat tissue (Longissimus dorsi of right half-carcass in 45 minutes, 2, 3, 4, 5, 6 hours and 24 hours after slaughter. Results were statistically elaborated using one-way variance analysis. Longissimus dorsi muscle pH values measured 45 minutes after slaughter in case of all groups of pigs were in range from 6.34 up to 6.47, what shows good meat quality. The lowest pH1 (measured 45 minutes after slaughter had meat of fatteners where addition of 2 % sunflower oil was given into fodder and the highest value of this trait was in group of individuals where also was given sunflower oil in 1 % amount. Statistical significant differences in pH value measured in different time after slaughter i.e. after 45 minutes, 2, 3, 4, 6 and 24 hours between tested groups of pigs were not stated. The exception is the result of pH measurement 5 hours after slaughter. Statistical significant differences were between group of pigs getting 0.5 % addition of conjugated linoleic acid characterized by the highest pH value of meat and group of animals fed the fodder with 1 % addition of conjugated linoleic acid (P≤0.01. On the basis of the results obtained in presented paper may be stated that feeding pigs with addition of conjugated linoleic acid in amounts 0.5; 1.0 and 2.0 % did not impact negatively on meat quality defined by pH value.

  8. Extreme value prediction of the wave-induced vertical bending moment in large container ships

    DEFF Research Database (Denmark)

    Andersen, Ingrid Marie Vincent; Jensen, Jørgen Juncher

    2015-01-01

    in the present paper is based on time series of full scale measurements from three large container ships of 8600, 9400 and 14000 TEU. When carrying out the extreme value estimation the peak-over-threshold (POT) method combined with an appropriate extreme value distribution is applied. The choice of a proper...... increase the extreme hull girder response significantly. Focus in the present paper is on the influence of the hull girder flexibility on the extreme response amidships, namely the wave-induced vertical bending moment (VBM) in hogging, and the prediction of the extreme value of the same. The analysis...... threshold level as well as the statistical correlation between clustered peaks influence the extreme value prediction and are taken into consideration in the present paper....

  9. Effect of extreme value loss on long-term correlated time series

    Science.gov (United States)

    Yuan, Naiming; Fu, Zuntao; Li, Huiqun; Mao, Jiangyu

    2012-07-01

    Effects of extreme value loss on long-term correlated time series are analyzed by means of detrended fluctuation analysis (DFA) and power spectral density analysis. Weaker memory can be detected after removing of extreme values for the artificial long-term correlated data, indicating the emergence of extreme events may be closely related to long-term memory. For observational temperature records, similar results are obtained, but not in all stations. For example, in some stations, only extending of scaling range to smaller time scales occurs, which may be due to the asymmetric distribution of values in the record. By comparing our findings with previous works, clustered positions of the extreme events are recognized as an important property in long-term correlated records. Through a simple numerical test, close relations between extreme events and long-term memory are discovered, which is helpful for our understanding of the effects of extreme value loss on long-term correlated records.

  10. Miscibility of Quillaja Saponins with other Co-surfactants under Different pH Values.

    Science.gov (United States)

    Reichert, Corina L; Salminen, Hanna; Leuenberger, Bruno H; Hinrichs, Jörg; Weiss, Jochen

    2015-11-01

    The miscibility behavior of mixed surfactant systems and the influence of extrinsic parameters are crucial for their application as emulsifiers. Therefore, the objective of this study was to evaluate the miscibility behavior of mixed systems composed of commercial Quillaja saponin and a co-surfactant, namely sodium caseinate, pea protein, rapeseed lecithin, or egg lecithin. These mixtures were evaluated macro- and microscopically at different concentration ratios (maximum concentration 5% w/v) at pH 3, 5, and 7 at 25 °C. The individual ingredients were also assessed for their charge properties and surface hydrophobicity. The results showed that Quillaja saponin-caseinate mixtures were miscible only at pH 7, and showed aggregation and precipitation at lower pH due to increasing electrostatic attraction forces. Rheological measurements showed that Quillaja saponin-pea protein mixtures formed gelled structures at all tested pH values mainly via association of hydrophobic patches. Quillaja saponins mixed with rapeseed lecithin were miscible at all tested pH values due to electrostatic repulsion. Quillaja saponin-egg lecithin mixtures aggregated independent of pH and concentration ratio. The microscopic analysis revealed that the lower the pH and the higher the Quillaja saponin ratio, the denser were the formed Quillaja saponin-egg lecithin aggregates. The results are summarized in ternary phase diagrams that provide a useful tool in selecting a surfactant system for food applications. © 2015 Institute of Food Technologists®

  11. Direct interaction between terbium ion and peroxidase in horseradish at different pH values.

    Science.gov (United States)

    Wang, Lihong; Zhou, Qing; Huang, Xiaohua

    2014-02-01

    Rare earth elements (REEs) entering plant cells can directly interact with peroxidase in plants, which is the structural basis for the decrease in the activity of peroxidase. Different cellular compartments have different pH values. However, little information is available regarding the direct interaction between REEs and peroxidase in plants at different pH values. Here, we investigated the charge distribution on the surface of horseradish peroxidase (HRP) molecule as well as the interaction of terbium ion (Tb(3+), one type of REEs) and HRP at different pH values. Using the molecular dynamics simulation, we found that when the pH value was from 4.0 to 8.0, a large amount of negative charges were intensively distributed on the surface of HRP molecule, and thus, we speculated that Tb(3+) with positive charges might directly interact with HRP at pH 4.0-8.0. Subsequently, using ultraviolet-visible spectroscopy, we demonstrated that Tb(3+) could directly interact with HRP in the simulated physiological solution at pH 7.0 and did not interact with HRP in other solutions at pH 5.0, pH 6.0 and pH 8.0. In conclusion, we showed that the direct interaction between Tb(3+) and HRP molecule depended on the pH value of cellular compartments.

  12. Most Likely Response Waves for Estimation of Extreme Value Ship Response Statistics

    DEFF Research Database (Denmark)

    Dietz, Jesper Skjoldager; Friis-Hansen, Peter; Jensen, Jørgen Juncher

    2004-01-01

    Fast and accurate methods for estimation of non-linear extreme value ship response statistics using 2D or 3D time-domain codes are of interest. The present study illustrates a new approach using Most Likely Response Waves (MLRW) to estimate the entire non-linear extreme response value distribution...

  13. Composition of calcium phosphates precipitated from aqueous solutions at different pH values

    Energy Technology Data Exchange (ETDEWEB)

    Salahi, E.; Moztarzadeh, F. [Ceramics Div., Teheran (Iran). Materials and Energy Research Center

    2001-03-01

    During the preparation of calcium phosphate compounds by precipitation from aqueous solutions, several phases, namely dicalcium hydrogen phosphate (DCP, CaHPO{sub 4}), dicalcium hydrogen phosphate dihydrate DCPD, CaHPO{sub 4} (2 H{sub 2}O), hydrated calcium phosphate Ca{sub 3}(PO){sub 4} 2(H{sub 2}O) and hydroxyapatite (HAp, Ca10(PO{sub 4})6(OH){sub 2}), can be formed at different pH values. In the research work presented here, Ca(NO{sub 3})2(4H{sub 2}O) and (NH{sub 4})2HPO{sub 4} were used as starting materials The two solutions with an initial molar ratio of Ca/P=1,67 were mixed at 20 C at 0<pH<13. The resulting precipitates were studied by means of X-ray diffraction, infrared spectroscopy and inductively coupled plasma techniques, before and after heating at 1100 C for 1 h. When the pH of the products are plotted against the pH of the reacting solutions, four pH regions can be distinguished: at pH<4, there is no precipitate, while between 4 and 8, DCP, DCPD and hydrated calcium phosphate are formed. A structural transition was observed at 8<pH<10, and finally hydroxyapatite is formed at higher pH values. In the heated precipitates, {beta}-Ca{sub 2}P{sub 2}O{sub 7} developed at pH 6..7, this phase became well crystallized; at pH 7..8, {beta}-tricalcium phosphate ({beta}-TCP,Ca{sub 3}(PO{sub 4}){sub 2}) developed. Between pH 8 and 9, this phase could be observed clearly. At pH 9..10, there is a transitional state, and at pH >10,5, the hydroxyapatite was developed completely. (orig.)

  14. An Extreme-Value Approach to Anomaly Vulnerability Identification

    Science.gov (United States)

    Everett, Chris; Maggio, Gaspare; Groen, Frank

    2010-01-01

    The objective of this paper is to present a method for importance analysis in parametric probabilistic modeling where the result of interest is the identification of potential engineering vulnerabilities associated with postulated anomalies in system behavior. In the context of Accident Precursor Analysis (APA), under which this method has been developed, these vulnerabilities, designated as anomaly vulnerabilities, are conditions that produce high risk in the presence of anomalous system behavior. The method defines a parameter-specific Parameter Vulnerability Importance measure (PVI), which identifies anomaly risk-model parameter values that indicate the potential presence of anomaly vulnerabilities, and allows them to be prioritized for further investigation. This entails analyzing each uncertain risk-model parameter over its credible range of values to determine where it produces the maximum risk. A parameter that produces high system risk for a particular range of values suggests that the system is vulnerable to the modeled anomalous conditions, if indeed the true parameter value lies in that range. Thus, PVI analysis provides a means of identifying and prioritizing anomaly-related engineering issues that at the very least warrant improved understanding to reduce uncertainty, such that true vulnerabilities may be identified and proper corrective actions taken.

  15. [Advances in the effects of pH value of micro-environment on wound healing].

    Science.gov (United States)

    Tian, Ruirui; Li, Na; Wei, Li

    2016-04-01

    Wound healing is a complex regeneration process, which is affected by lots of endogenous and exogenous factors. Researches have confirmed that acid environment could prevent wound infection and accelerate wound healing by inhibiting bacteria proliferation, promoting oxygen release, affecting keratinocyte proliferation and migration, etc. In this article, we review the literature to identify the potential relationship between the pH value of wound micro-environment and the progress of wound healing, and summarize the clinical application of variation of pH value of micro-environment in wound healing, thereby to provide new treatment strategy for wound healing.

  16. Numerical convergence of the block-maxima approach to the Generalized Extreme Value distribution

    CERN Document Server

    Faranda, Davide; Turchetti, Giorgio; Vaienti, Sandro

    2011-01-01

    In this paper we perform an analytical and numerical study of Extreme Value distributions in discrete dynamical systems. In this setting, recent works have shown how to get a statistics of extremes in agreement with the classical Extreme Value Theory. We pursue these investigations by giving analytical expressions of Extreme Value distribution parameters for maps that have an absolutely continuous invariant measure. We compare these analytical results with numerical experiments in which we study the convergence to limiting distributions using the so called block-maxima approach, pointing out in which cases we obtain robust estimation of parameters. In regular maps for which mixing properties do not hold, we show that the fitting procedure to the classical Extreme Value Distribution fails, as expected. However, we obtain an empirical distribution that can be explained starting from a different observable function for which Nicolis et al. [2006] have found analytical results.

  17. An application of extreme value theory in estimating liquidity risk

    OpenAIRE

    Sonia Benito Muela; Carmen López Martín; Raquel Arguedas Sanz

    2017-01-01

    The last global financial crisis (2007–2008) has highlighted the weaknesses of value at risk (VaR) as a measure of market risk, as this metric by itself does not take liquidity risk into account. To address this problem, the academic literature has proposed incorporating liquidity risk into estimations of market risk by adding the VaR of the spread to the risk price. The parametric model is the standard approach used to estimate liquidity risk. As this approach does not generate reliable VaR ...

  18. Generalized Extreme Value's shape parameter and its nature for extreme precipitation using long time series and Bayesian approach

    Science.gov (United States)

    Ragulina, Galina; Reitan, Trond

    2016-04-01

    Assessing the probability of extreme precipitation events is of great importance in civil planning. This requires understanding of how return values change with different return periods, which is essentially described by the Generalized Extreme Value distribution's shape parameter. Some works in the field have suggested a constant shape parameter, while our analysis indicates a non-universal value. We first re-analyse an older precipitation dataset (169 stations) extended by Norwegian data (71 stations). We show that while each set seems to have a constant shape parameter, it differs between the two datasets, indicating regional differences. For a more comprehensive analysis of spatial effects, we examine a global dataset (1495 stations). We provide shape parameter maps for two models. We find clear evidence for the shape parameter being dependent on elevation while the effect of latitude remains uncertain. Our results confirm an explanation in terms of dominating precipitation systems based on a proxy derived from the Köppen-Geiger climate classification.

  19. Statistical analysis of extreme values for geomagnetic and geoelectric field variations for Canada

    Science.gov (United States)

    Nikitina, Lidia; Trichtchenko, Larisa; Boteler, David

    2016-04-01

    Disturbances of the geomagnetic field produced by space weather events cause variable geoelectric fields at Earth's surface which drive electric currents in power systems, resulting in hazardous impacts on electric power transmission. In extreme cases, as during the magnetic storm in March 13, 1989, this can result in burnt-out transformers and power blackouts. To make assessment of geomagnetic and geoelectric activity in Canada during extreme space weather events, extreme value statistical analysis has been applied to more than 40 years of magnetic data from the Canadian geomagnetic observatories network. This network has archived digital data recordings for observatories located in sub-auroral, auroral, and polar zones. Extreme value analysis was applied to hourly ranges of geomagnetic variations as an index of geomagnetic activity and to hourly maximum of rate-of-change of geomagnetic field. To estimate extreme geoelectric fields, the minute geomagnetic data were used together with Earth conductivity models for different Canadian locations to calculate geoelectric fields. The extreme value statistical analysis was applied to hourly maximum values of the horizontal geoelectric field. This assessment provided extreme values of geomagnetic and geoelectric activity which are expected to happen once per 50 years and once per 100 years. The results of this analysis are designed to be used to assess the geomagnetic hazard to power systems and help the power industry mitigate risks from extreme space weather events.

  20. Influence of pH value on Cu (II biosorption by lignocellulose peach shell waste material

    Directory of Open Access Journals (Sweden)

    Lopičić Zorica R.

    2013-01-01

    Full Text Available In the last decade, the pollution made by anthropogenic sources has reached large amounts with special attention on heavy metals because of their high toxicity, persistence and bioaccumulation tendency. Since the conventional methods for their removing are either too expensive or create large quantities of toxic sludge, the great attention has been paid to the new technologies such as biosorption, technology that use cheap, abundant, organic waste for sequestering pollutants from contaminated mediums. Among the other factors that affect biosorption process, pH value is one the most important because it directs both the metal solution chemistry as well as the activity of the biomass functional groups. In this paper the influence of pH value on biosorption of Cu (II by unmodified low-cost lignocellulose biosorbent - peach shell (PS particles, have been studied. The chemical composition of PS, point of zero charge (pHPZC as well as its surface morphology is also presented. Results have showed that this biosorbent contains mainly cellulose and lignin, the components that carry the functional groups responsible for metal binding. Its multilayer surface contains many pores and channels that help diffusion in deeper layers and force biosorption process. Point of zero charge determination was performed with three different KNO3 ionic strengths: 0,1M, 0,01M and 0,001M. The obtained value for pHPZC was 4,75±0,1 and showed that this biosorbent is non-sensitive to ionic strength of electrolyte applied. Biosorption experiments were done with peach shell particles whose diameter was -0,5+0,1mm at 25oC . The initial copper (II concentration was 50 mg/dm3 while the biosorbent concentration was 10g/dm3. Experiments were done with and without keeping pH constant. The influence of pH on biosorption process was examined in 2-6 pH range. The percentage of Cu (II removed by PS, reaches its maximum at pH 6, with the 90,43% removing but this percentage can also be

  1. Value-at-Risk-Estimation in the Mexican Stock Exchange Using Conditional Heteroscedasticity Models and Theory of Extreme Values

    OpenAIRE

    Alejandro Iván Aguirre Salado; Humberto Vaquera Huerta; Martha Elva Ramírez Guzmán; José René Valdez Lazalde; Carlos Arturo Aguirre Salado

    2013-01-01

    This work proposes an approach for estimating value at risk (VaR) of the Mexican stock exchange index (IPC) by using a combination of the autoregressive moving average models (ARMA); three different models of the arch family, one symmetric (GARCH) and two asymmetric (GJR-GARCH and EGARCH); and the extreme value theory (EVT). The ARMA models were initially used to obtain uncorrelated residuals, which were later used for the analysis of extreme values. The GARCH, EGARCH and GJR-GARCH models, by...

  2. Statistical analysis of extreme values from insurance, finance, hydrology and other fields

    CERN Document Server

    Reiss, Rolf-Dieter

    1997-01-01

    The statistical analysis of extreme data is important for various disciplines, including hydrology, insurance, finance, engineering and environmental sciences. This book provides a self-contained introduction to the parametric modeling, exploratory analysis and statistical interference for extreme values. The entire text of this third edition has been thoroughly updated and rearranged to meet the new requirements. Additional sections and chapters, elaborated on more than 100 pages, are particularly concerned with topics like dependencies, the conditional analysis and the multivariate modeling of extreme data. Parts I–III about the basic extreme value methodology remain unchanged to some larger extent, yet notable are, e.g., the new sections about "An Overview of Reduced-Bias Estimation" (co-authored by M.I. Gomes), "The Spectral Decomposition Methodology", and "About Tail Independence" (co-authored by M. Frick), and the new chapter about "Extreme Value Statistics of Dependent Random Variables" (co-authored ...

  3. [Investigation of apomyoglobin stability depending on urea and temperature at two different pH values].

    Science.gov (United States)

    Baryshnikova, E N; Sharanov, M G; Kashparov, I A; Il'ina, N B; Bychkova, V E

    2005-01-01

    Equilibrium unfolding of apomyoglobin by urea was investigated in the temperature range from 5 to 25 degrees C at two pH values. The thermodynamic parameters of the apomyoglobin native-unfolded state transition were determined. Conformational changes in the protein structure were monitored by tryptophan fluorescence and far UV circular dichroism. Apomyoglobin preserves its native conformation at pH 5.7 and 6.2 in the temperature range used. It was shown that the apomyoglobin stability and its unfolding cooperativity are substantially lower at 5 degrees C than at other temperatures. This fact should be taken in account at the investigation of apomyoglobin.

  4. Extremism reduces conflict arousal and increases values affirmation in response to meaning violations

    NARCIS (Netherlands)

    Sleegers, W.W.A.; Proulx, T.; van Beest, I.

    2015-01-01

    In the social psychological threat-compensation literature, there is an apparent contradiction whereby relatively extreme beliefs both decrease markers of physiological arousal following meaning violations, and increase the values affirmation behaviors understood as a palliative responses to this

  5. Extremism reduces conflict arousal and increases values affirmation in response to meaning violations

    NARCIS (Netherlands)

    Sleegers, W.W.A.; Proulx, T.; van Beest, I.

    2015-01-01

    In the social psychological threat-compensation literature, there is an apparent contradiction whereby relatively extreme beliefs both decrease markers of physiological arousal following meaning violations, and increase the values affirmation behaviors understood as a palliative responses to this ar

  6. Bias and spread in extreme value theory measurements of probability of error

    Science.gov (United States)

    Smith, J. G.

    1972-01-01

    Extreme value theory is examined to explain the cause of the bias and spread in performance of communications systems characterized by low bit rates and high data reliability requirements, for cases in which underlying noise is Gaussian or perturbed Gaussian. Experimental verification is presented and procedures that minimize these effects are suggested. Even under these conditions, however, extreme value theory test results are not particularly more significant than bit error rate tests.

  7. Extreme values and the level-crossing problem: an application to the Feller process.

    Science.gov (United States)

    Masoliver, Jaume

    2014-04-01

    We review the question of the extreme values attained by a random process. We relate it to level crossings to one boundary (first-passage problems) as well as to two boundaries (escape problems). The extremes studied are the maximum, the minimum, the maximum absolute value, and the range or span. We specialize in diffusion processes and present detailed results for the Wiener and Feller processes.

  8. Extreme values and the level-crossing problem: An application to the Feller process

    Science.gov (United States)

    Masoliver, Jaume

    2014-04-01

    We review the question of the extreme values attained by a random process. We relate it to level crossings to one boundary (first-passage problems) as well as to two boundaries (escape problems). The extremes studied are the maximum, the minimum, the maximum absolute value, and the range or span. We specialize in diffusion processes and present detailed results for the Wiener and Feller processes.

  9. Extremism reduces conflict arousal and increases values affirmation in response to meaning violations.

    Science.gov (United States)

    Sleegers, Willem W A; Proulx, Travis; van Beest, Ilja

    2015-05-01

    In the social psychological threat-compensation literature, there is an apparent contradiction whereby relatively extreme beliefs both decrease markers of physiological arousal following meaning violations, and increase the values affirmation behaviors understood as a palliative responses to this arousal. We hypothesize that this is due to the differential impact of measuring extremism on behavioral inhibition and approach systems following meaning violations, whereby extremism both reduces markers of conflict arousal (BIS) and increases values affirmation (BAS) unrelated to this initial arousal. Using pupil dilation as a proxy for immediate conflict arousal, we found that the same meaning violation (anomalous playing cards) evoked greater pupil dilation, and that this pupillary reaction was diminished in participants who earlier reported extreme beliefs. We also found that reporting extreme beliefs was associated with greater affirmation of an unrelated meaning framework, where this affirmation was unrelated to physiological markers of conflict arousal. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Traumatic extremity arterial injury in children: Epidemiology, diagnostics, treatment and prognostic value of Mangled Extremity Severity Score

    Directory of Open Access Journals (Sweden)

    Lange Nadine

    2010-04-01

    Full Text Available Abstract Background Traumatic paediatric arterial injuries are a great challenge due to low incidence and specific characteristics of paediatric anatomy and physiology. The aim of the present study was to investigate their epidemiology, diagnostic and therapeutic options and complications. Furthermore, the prognostic value of the Mangled Extremity Severity Score (MESS was evaluated. Methods In a retrospective clinical study 44 children aged 9.0 ± 3.2 years treated for traumatic extremity arterial lesions in our Level I trauma center between 1971 and 2006 were enrolled. Exclusion criteria were age > 14, venous and iatrogenic vascular injury. Demographic data, mechanism of injury, severity of arterial lesions (by Vollmar and MESS, diagnostic and therapeutic management, complications and outcome were evaluated. Results The most commonly injured vessel was the femoral artery (25% followed by the brachial artery (22.7%. The mechanism of injury was penetrating (31.8%, isolated severe blunt extremity trauma (29.6%, multiple trauma (25% and humeral supracondylar fractures (13.6%. In 63.6% no specific vascular diagnostic procedure was performed in favour of emergency surgery. Surgical reconstructive strategies were preferred (68.2%. A MESS Conclusions Traumatic paediatric vascular injuries are very rare. The most common situations of vascular lesions in childhood were penetrating injuries and fractures of the extremities either as isolated injuries or in multiply injured patients. In paediatric patients, the MESS could serve as a basis for decision making for limb salvage or amputation.

  11. Improvement of physicomechanical properties of carbamazepine by recrystallization at different pH values.

    Science.gov (United States)

    Javadzadeh, Yousef; Mohammadi, Ameneh; Khoei, Nazaninossadat Seyed; Nokhodchi, Ali

    2009-06-01

    The morphology of crystals has an appreciable impact role on the physicochemical properties of drugs. Drug properties such as flowability, dissolution, hardness and bioavailability may be affected by crystallinity behaviours of drugs. The objective of this study was to achieve an improved physicomechanical property of carbamazepine powder through recrystallization from aqueous solutions at different pH values. For this purpose, carbamazapine was recrystallized from aqueous solutions at different pH values (1, 7, 11). The morphology of crystals was investigated using scanning electron microscopy; X-ray powder diffraction (XRPD) was used to identify polymorphism; thermodynamic properties were analyzed using differential scanning calorimetery (DSC). Dissolution rate was determined using USP dissolution apparatus. Mechanical behavior of recrystallized carbamazepine powders was investigated by making tablets under different compaction pressure and measuring their hardness. SEM studies showed that the carbamazepine crystallization in different media affected the morphology and size of carbamazepine crystals. The shape of carbamazepine crystals changed from flaky or thin plate-like to needle shape. XRPD and DSC results ruled out any crystallinity changes occurring due to the temperature during recrystallization procedure or pH of crystallization media. The crushing strength of tablets indicated that all of the recrystallized carbamazepine samples had better compactiblity than the original carbamazepine powder. In vitro dissolution studies of carbamazepine samples showed a higher dissolution rate for carbamazepine crystals obtained from media with pH 11 and 1. Carbamazepine particles recrystallized from aqueous solutions of different pH values (all media) appeared to have superior mechanical properties to those of the original carbamazepine sample.

  12. [The effects of electromagnetic radiation of extremely high frequency and low intensity on the growth rate of bacteria Escherichia coli and the role of medium pH].

    Science.gov (United States)

    Tadevosian, A; Kalantarian, V; Trchunian, A

    2007-01-01

    It has been shown that coherent electromagnetic irradiation (EMI) of extremely high frequency (45-53 GHz) or millimeter waves (wavelength 5.6-6.7 mm) of low intensity (flux capacity 0.06 mW/cm2) of Escherichia coli K12, grown under anaerobic conditions during the fermentation of sugar (glucose) for 30 min or 1 h, caused a decrease in their growth rate, the maximum inhibitory effect being achieved at a frequency of 51.8 or 53 GHz. This effect depended on medium pH when the maximal action was determined at pH 7.5. In addition, separate 30-min of 1-h irradiation (frequency 51.8 or 53 GHz) of doubly distilled water or some inorganic ions contained in Tris-phosphate buffer where the cells were transferred induced oppositely directed changes in further growth of these bacteria under anaerobic conditions; irradiation of water caused a decrease in the growth rate of bacteria. A significant change in pH of water (0.5-1.5 unit) was induced by a 30-irradiation at a frequency of 49, 50.3, 51.8, or 53 GHz, when the initial pH value was 6.0 or 8.0, but not 7.5. These results indicate the changes in the properties of water and its role in the effects of EMI of extremely high frequency. The marked effect of EMI on bacteria disappeared upon repeated irradiation for 1 h at a frequency of 51.8 or 53 GHz with an interval of 2 hours. This result indicates some compensatory mechanisms in bacteria.

  13. Comparison among Different pH Values of Rhodamine B Solution Impregnated into Mesoporous Silica

    Directory of Open Access Journals (Sweden)

    Juliana Jorge

    2013-05-01

    Full Text Available We studied the behavior of different pH values of Rhodamine B solution impregnated into pores of mesoporous silica, through structural characterization techniques, such as scanning electron microscopy and porosity measurements, and spectroscopic characterization techniques, such as infrared and luminescence spectroscopy; in order to applications in luminescence. Because, Rhodamine B is an interesting xanthene dye whose optical properties depend of many factors, dye concentration and pH values. MSU-4 type mesoporous silica has been synthesized with Tween 60 surfactant as directing-structure agent and tetraethyl orthosilicate (Si(OEt4, TEOS as silica source. The mesoporous structures doped with dyes are promissory materials for several applications, for example, optical sensors and biomarkers.

  14. Chloride content and pH value in the pore solution of concrete under carbonation

    Institute of Scientific and Technical Information of China (English)

    Xiao-mei WAN; Folker H.WITTMANN; Tie-jun ZHAO; Hong FAN

    2013-01-01

    Chloride content and the pH value of the pore solution in the neighborhood of steel reinforcement are decisive parameters for initiation and rate of corrosion.The pore solution of cement mortar and hardened cement paste has been expressed from the pore space by high pressure in the investigation.The influence of the water-cement ratio,age,and addition of chloride to the fresh mix on chloride content in the pore solution has been determined by ion chromatography.At the same time the pH value of the pore solution has been determined.The dissolved chloride content decreases with increase in the water-cement ratio.The amount of bound chloride increases with time,but it decreases with decreasing content of dissolved chloride in the pore solution.A significant influence of carbonation on the dissolved chloride content of the pore solution has been observed.With complete carbonation,the dissolved chloride content in cement mortar and hardened cement paste increases by a factor between 2 and 12.The bound chloride decreases by 27%-54%.As expected,the pH value decreases from around 13.2 to as low as 8.0 due to carbonation.It can be concluded that carbonation not only lowers the pH value but liberates bound chloride.This is one obvious reason why the combined action of chloride penetration and carbonation accelerates steel corrosion and shortens the service life of reinforced concrete structures.

  15. Effects of pH value and coagulant dosage on contact filtration of humic substances

    Institute of Scientific and Technical Information of China (English)

    蒋绍阶; 刘宗源; 梁建军

    2009-01-01

    Humic substances (especially fulvic acid (FA)) are the major components of natural organic matter (NOM) that widely exist in drinking water source. Due to their potential effects on public health,the removal of FA was one of the main concerns during the water treatment. Therefore,the contact filtration of FA by using aluminum sulfate as coagulant on the basis of jar tests was carried out. The effects of pH and coagulant dosage on the FA removal and the development of head loss were investigated. The results show that the range of pH value during the FA contact filtration can be effectively influenced by the dosage of aluminum sulfate,and the high aluminum sulfate dosage is an important factor that can result in early filter breakthrough. The FA filtration by deep-bed filtration or by membrane filtration is sometimes disparate under the same coagulation conditions. The choice of aluminum sulfate dosage by the method of membrane filtration,i.e. the "true color measurement",may result in inappropriate filter run,whereas it can be determined with simple jar tests by observing the formation of micro flocs. Considering the effects of pH on aluminum sulfate dosage and FA removal,the optimal pH range of 5.5?6.0 is suggested.

  16. Examining personal values in extreme environment contexts: Revisiting the question of generalizability

    Science.gov (United States)

    Smith, N.; Sandal, G. M.; Leon, G. R.; Kjærgaard, A.

    2017-08-01

    Land-based extreme environments (e.g. polar expeditions, Antarctic research stations, confinement chambers) have often been used as analog settings for spaceflight. These settings share similarities with the conditions experienced during space missions, including confinement, isolation and limited possibilities for evacuation. To determine the utility of analog settings for understanding human spaceflight, researchers have examined the extent to which the individual characteristics (e.g., personality) of people operating in extreme environments can be generalized across contexts (Sandal, 2000) [1]. Building on previous work, and utilising new and pre-existing data, the present study examined the extent to which personal value motives could be generalized across extreme environments. Four populations were assessed; mountaineers (N =59), military personnel (N = 25), Antarctic over-winterers (N = 21) and Mars simulation participants (N = 12). All participants completed the Portrait Values Questionnaire (PVQ; Schwartz; 2) capturing information on 10 personal values. Rank scores suggest that all groups identified Self-direction, Stimulation, Universalism and Benevolence as important values and acknowledged Power and Tradition as being low priorities. Results from difference testing suggest the extreme environment groups were most comparable on Self-direction, Stimulation, Benevolence, Tradition and Security. There were significant between-group differences on five of the ten values. Overall, findings pinpointed specific values that may be important for functioning in challenging environments. However, the differences that emerged on certain values highlight the importance of considering the specific population when comparing results across extreme settings. We recommend that further research examine the impact of personal value motives on indicators of adjustment, group working, and performance. Information from such studies could then be used to aid selection and

  17. Survival of the faucet snail after chemical disinfection, pH extremes, and heated water bath treatments

    Science.gov (United States)

    Mitchell, A.J.; Cole, R.A.

    2008-01-01

    The faucet snail Bithynia tentaculata, a nonindigenous aquatic snail from Eurasia, was introduced into Lake Michigan in 1871 and has spread to the mid-Atlantic states, the Great Lakes region, Montana, and most recently, the Mississippi River. The faucet snail serves as intermediate host for several trematodes that have caused large-scale mortality among water birds, primarily in the Great Lakes region and Montana. It is important to limit the spread of the faucet snail; small fisheries equipment can serve as a method of snail distribution. Treatments with chemical disinfection, pH extremes, and heated water baths were tested to determine their effectiveness as a disinfectant for small fisheries equipment. Two treatments eliminated all test snails: (1) a 24-h exposure to Hydrothol 191 at a concentration of at least 20 mg/L and (2) a treatment with 50??C heated water for 1 min or longer. Faucet snails were highly resistant to ethanol, NaCl, formalin, Lysol, potassium permanganate, copper sulfate, Baquacil, Virkon, household bleach, and pH extremes (as low as 1 and as high as 13).

  18. COLOUR AND pH VALUE OF ISTRIAN SHEEP LAMBS MEAT

    Directory of Open Access Journals (Sweden)

    Valentino Držaić

    2016-06-01

    Full Text Available The aim of the present study was to evaluate the effect of sex and slaughter weight of Istrian sheep lambs on pH value and meat colour. The study included 118 lambs of both sexes (64 male and 54 female which were, prior slaughter, divided into two groups: light (17.76 kg; 28 male and 32 female and heavy (20.17 kg; 3 male and 22 female. Carcass weight was determined immediately after carcass processing and after 24 hours, while the pH value and meat colour were determined 45 minutes and 24 hours after slaughter. Average hot and cold carcass weights in light lambs were 9.76 and 9.47 kg, and in heavy lambs 11.80 and 11.49 kg, with chilling loss of 2.96 and 2.60% respectively. Istrian sheep lambs carcasses are quite uniform in relation to sex in terms of all the investigated traits, except value of L* and a* colour parameters. For the production of larger lamb meat quantities it might be recommended to increase lambs slaughter weight since the higher slaughter weight has the positive effect on carcass weight and chilling loss while retaining the desirable values of meat quality parameters.

  19. Assessment of extreme values in geomagnetic and geoelectric field variations for Canada

    Science.gov (United States)

    Nikitina, L.; Trichtchenko, L.; Boteler, D. H.

    2016-07-01

    Disturbances of the geomagnetic field produced by space weather events can have an impact on power systems and other critical infrastructure. To mitigate these risks it is important to determine the extreme values of geomagnetic activity that can occur. More than 40 years of 1 min magnetic data recorded at 13 Canadian geomagnetic observatories have been analyzed to evaluate extreme levels in geomagnetic and geoelectric activities in different locations of Canada. The hourly ranges of geomagnetic field variations and hourly maximum in rate of change of the magnetic variations have been used as measures of geomagnetic activity. Geoelectric activity is estimated by the hourly peak amplitude of the geoelectric fields calculated with the use of Earth resistivity models specified for different locations in Canada. A generalized extreme value distribution was applied to geomagnetic and geoelectric indices to evaluate extreme geomagnetic and geoelectric disturbances, which could happen once per 50 and once per 100 years with 99% confidence interval. Influence of geomagnetic latitude and Earth resistivity models on the results for the extreme geomagnetic and geoelectric activity is discussed. The extreme values provide criteria for assessing the vulnerability of power systems and other technology to geomagnetic activity for design or mitigation purposes.

  20. Predictive value of gastric intramucosal pH for critical patients

    Institute of Scientific and Technical Information of China (English)

    Hong Tao; Bing Wen Jing; Shu Zhen Li; Xiang Yu Zhang

    2000-01-01

    AIM To observe the predictive value of gastric intramucosal pH (pHi) for critical patients.METHODS The gastric intramucosal pH (pHi) of 32 ICU patients was measured with a self-madegastrointestinal tonometer, and the APACHE l score was determined simultaneously.RESULTS pHi of the nonsurvivors was significantly lower than that of the survivors (P<0.05). The pHiwas remarkably higher in the nonsepsis group than in the sepsis group (P<0.01). Only in multiple organfailure groups, pHi was found statistically lower (P<0.05).CONCLUSION pHi may be the most simple, reliable, sensitive and accurate parameter to indicate theadequacy of tissue oxygenation, and it may be widely used in ICU monitoring in near future.

  1. Estimation of the value-at-risk parameter: Econometric analysis and the extreme value theory approach

    Directory of Open Access Journals (Sweden)

    Mladenović Zorica

    2006-01-01

    Full Text Available In this paper different aspects of value-at-risk estimation are considered. Daily returns of CISCO, INTEL and NASDAQ stock indices are analyzed for period: September 1996 - September 2006. Methods that incorporate time varying variability and heavy tails of the empirical distributions of returns are implemented. The main finding of the paper is that standard econometric methods underestimate the value-at-risk parameter if heavy tails of the empirical distribution are not explicitly taken into account. .

  2. 食品的 pH 值与微生物控制%PH value and microbial control of food

    Institute of Scientific and Technical Information of China (English)

    赵君哲

    2015-01-01

    介绍了食品中 pH 值对微生物的影响;酸性食品与低酸性食品的不同,以及对微生物控制的操作差异。%The effect of the pH value of food on microbial was introduced. The difference of acid food and low acidity food and the different operation of microbial control were studied.

  3. Micro Electrochemical pH Sensor Applicable for Real-Time Ratiometric Monitoring of pH Values in Rat Brains.

    Science.gov (United States)

    Zhou, Jie; Zhang, Limin; Tian, Yang

    2016-02-16

    To develop in vivo monitoring meter for pH measurements is still the bottleneck for understanding the role of pH plays in the brain diseases. In this work, a selective and sensitive electrochemical pH meter was developed for real-time ratiometric monitoring of pH in different regions of rat brains upon ischemia. First, 1,2-naphthoquinone (1,2-NQ) was employed and optimized as a selective pH recognition element to establish a 2H(+)/2e(-) approach over a wide range of pH from 5.8 to 8.0. The pH meter demonstrated remarkable selectivity toward pH detection against metal ions, amino acids, reactive oxygen species, and other biological species in the brain. Meanwhile, an inner reference, 6-(ferrocenyl)hexanethiol (FcHT), was selected as a built-in correction to avoid the environmental effect through coimmobilization with 1,2-NQ. In addition, three-dimensional gold nanoleaves were electrodeposited onto the electrode surface to amplify the signal by ∼4.0-fold and the measurement was achieved down to 0.07 pH. Finally, combined with the microelectrode technique, the microelectrochemical pH meter was directly implanted into brain regions including the striatum, hippocampus, and cortex and successfully applied in real-time monitoring of pH values in these regions of brain followed by global cerebral ischemia. The results demonstrated that pH values were estimated to 7.21 ± 0.05, 7.13 ± 0.09, and 7.27 ± 0.06 in the striatum, hippocampus, and cortex in the rat brains, respectively, in normal conditions. However, pH decreased to 6.75 ± 0.07 and 6.52 ± 0.03 in the striatum and hippocampus, upon global cerebral ischemia, while a negligible pH change was obtained in the cortex.

  4. Programs to Compute Distribution Functions and Critical Values for Extreme Value Ratios for Outlier Detection

    Directory of Open Access Journals (Sweden)

    George C. McBane

    2006-05-01

    Full Text Available A set of FORTRAN subprograms is presented to compute density and cumulative distribution functions and critical values for the range ratio statistics of Dixon (1951, The Annals of Mathematical Statistics These statistics are useful for detection of outliers in small samples.

  5. Validation of extremes within the Perfect-Predictor Experiment of the COST Action VALUE

    Science.gov (United States)

    Hertig, Elke; Maraun, Douglas; Wibig, Joanna; Vrac, Mathieu; Soares, Pedro; Bartholy, Judith; Pongracz, Rita; Mares, Ileana; Gutierrez, Jose Manuel; Casanueva, Ana; Alzbutas, Robertas

    2016-04-01

    Extreme events are of widespread concern due to their damaging consequences on natural and anthropogenic systems. From science to applications the statistical attributes of rare and infrequent occurrence and low probability become connected with the socio-economic aspect of strong impact. Specific end-user needs regarding information about extreme events depend on the type of application, but as a joining element there is always the request for easily accessible climate change information with a clear description of their uncertainties and limitations. Within the Perfect-Predictor Experiment of the COST Action VALUE extreme indices modelled from a wide range of downscaling methods are compared to reference indices calculated from observational data. The experiment uses reference data from a selection of 86 weather stations representative of the different climates in Europe. Results are presented for temperature and precipitation extremes and include aspects of the marginal distribution as well as spell-length related aspects.

  6. Redox Transformations of Iron at Extremely Low pH: Fundamental and Applied Aspects

    Science.gov (United States)

    Johnson, D. Barrie; Kanao, Tadayoshi; Hedrich, Sabrina

    2012-01-01

    Many different species of acidophilic prokaryotes, widely distributed within the domains Bacteria and Archaea, can catalyze the dissimilatory oxidation of ferrous iron or reduction of ferric iron, or can do both. Microbially mediated cycling of iron in extremely acidic environments (pH iron and far greater solubility of ferric iron under such conditions. Cycling of iron has been demonstrated in vitro using both pure and mixed cultures of acidophiles, and there is considerable evidence that active cycling of iron occurs in acid mine drainage streams, pit lakes, and iron-rich acidic rivers, such as the Rio Tinto. Measurements of specific rates of iron oxidation and reduction by acidophilic microorganisms show that different species vary in their capacities for iron oxido-reduction, and that this is influenced by the electron donor provided and growth conditions used. These measurements, and comparison with corresponding data for oxidation of reduced sulfur compounds, also help explain why ferrous iron is usually used preferentially as an electron donor by acidophiles that can oxidize both iron and sulfur, even though the energy yield from oxidizing iron is much smaller than that available from sulfur oxidation. Iron-oxidizing acidophiles have been used in biomining (a technology that harness their abilities to accelerate the oxidative dissolution of sulfidic minerals and thereby facilitate the extraction of precious and base metals) for several decades. More recently they have also been used to simultaneously remediate iron-contaminated surface and ground waters and produce a useful mineral by-product (schwertmannite). Bioprocessing of oxidized mineral ores using acidophiles that catalyze the reductive dissolution of ferric iron minerals such as goethite has also recently been demonstrated, and new biomining technologies based on this approach are being developed. PMID:22438853

  7. Effect of pH value on electromagnetic loss properties of Co–Zn ferrite prepared via coprecipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xiaogu, E-mail: nthxg@126.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science & Technology, Nanjing 210044 (China); School of Material Science and Engineering, Georgia Institute of Technology, Atlanta 30332 (United States); Zhang, Jing [Nanjing Center, China Geological Survey, Nanjing 210016 (China); Wang, Wei [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Sang, Tianyi [Department of Electrical and Computer Engineering, University of California Davis, Davis 95616 (United States); Song, Bo [School of Material Science and Engineering, Georgia Institute of Technology, Atlanta 30332 (United States); Zhu, Hongli [Institute 53 of China North Industries Group Corporation, Jinan 250031 (China); Rao, Weifeng [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Wong, Chingping [School of Material Science and Engineering, Georgia Institute of Technology, Atlanta 30332 (United States)

    2016-05-01

    In this paper, the cobalt zinc ferrite was prepared by coprecipitation method at different pH conditions. The influence of pH values on the coprecipitation reaction was theoretically analyzed at first. The calculated results showed that the pH values should be controlled in the range of 9–11 to form the stable precipitation. The XRD investigation was used to further confirm the formation of the composite on specific pH values. In addition, the morphological study revealed that the average particle size of the composite decreased from 40 nm to 30 nm when the pH value increased from 9–11. The variation of microstructure plays a critical role in controlling the electromagnetic properties. From the electromagnetic analysis, the dielectric loss factor was 0.02–0.07 and magnetic loss factor was 0.2–0.5 for the composite synthesized at pH of 9, which presents dramatically improved dielectric loss and magnetic loss properties than the samples prepared at pH of 10 and 11. The as-prepared cobalt zinc ferrite are highly promising to be used as microwave absorption materials. - Highlights: • Co–Zn ferrite was prepared by coprecipitation method with different pH values. • To obtain pure Co–Zn ferrite, the theoretical pH values were 9–11. • Microstructure and electromagnetic properties can be tuned by varying pH values. • Co–Zn ferrite prepared with pH=9 performed well electromagnetic loss properties.

  8. Estimation of Extreme Values by the Average Conditional Exceedance Rate Method

    Directory of Open Access Journals (Sweden)

    A. Naess

    2013-01-01

    Full Text Available This paper details a method for extreme value prediction on the basis of a sampled time series. The method is specifically designed to account for statistical dependence between the sampled data points in a precise manner. In fact, if properly used, the new method will provide statistical estimates of the exact extreme value distribution provided by the data in most cases of practical interest. It avoids the problem of having to decluster the data to ensure independence, which is a requisite component in the application of, for example, the standard peaks-over-threshold method. The proposed method also targets the use of subasymptotic data to improve prediction accuracy. The method will be demonstrated by application to both synthetic and real data. From a practical point of view, it seems to perform better than the POT and block extremes methods, and, with an appropriate modification, it is directly applicable to nonstationary time series.

  9. Extreme-value statistics of intensities in a cw-pumped random fiber laser

    Science.gov (United States)

    Lima, Bismarck C.; Pincheira, Pablo I. R.; Raposo, Ernesto P.; Menezes, Leonardo de S.; de Araújo, Cid B.; Gomes, Anderson S. L.; Kashyap, Raman

    2017-07-01

    We report on the extreme-value statistics of output intensities in a one-dimensional cw-pumped erbium-doped random fiber laser, with a strongly scattering disordered medium consisting of randomly spaced Bragg gratings. The experimental findings from the analysis of a large number of emission spectra are well described by the Gumbel distribution below and above the laser threshold, whereas the Fréchet distribution, typical of strongly fluctuating extreme events with heavy power-law probability tails, provides a nice support to the data near the threshold. We establish a close connection, relying on theoretical arguments, between the reported extreme-value statistics and the shifts in the statistics of intensity fluctuations, from the Gaussian to the Lévy distribution at the threshold and back to the Gaussian well above threshold.

  10. Assessing Regional Scale Variability in Extreme Value Statistics Under Altered Climate Scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Brunsell, Nathaniel [Univ. of Kansas, Lawrence, KS (United States); Mechem, David [Univ. of Kansas, Lawrence, KS (United States); Ma, Chunsheng [Wichita State Univ., KS (United States)

    2015-02-20

    Recent studies have suggested that low-frequency modes of climate variability can significantly influence regional climate. The climatology associated with extreme events has been shown to be particularly sensitive. This has profound implications for droughts, heat waves, and food production. We propose to examine regional climate simulations conducted over the continental United States by applying a recently developed technique which combines wavelet multi–resolution analysis with information theory metrics. This research is motivated by two fundamental questions concerning the spatial and temporal structure of extreme events. These questions are 1) what temporal scales of the extreme value distributions are most sensitive to alteration by low-frequency climate forcings and 2) what is the nature of the spatial structure of variation in these timescales? The primary objective is to assess to what extent information theory metrics can be useful in characterizing the nature of extreme weather phenomena. Specifically, we hypothesize that (1) changes in the nature of extreme events will impact the temporal probability density functions and that information theory metrics will be sensitive these changes and (2) via a wavelet multi–resolution analysis, we will be able to characterize the relative contribution of different timescales on the stochastic nature of extreme events. In order to address these hypotheses, we propose a unique combination of an established regional climate modeling approach and advanced statistical techniques to assess the effects of low-frequency modes on climate extremes over North America. The behavior of climate extremes in RCM simulations for the 20th century will be compared with statistics calculated from the United States Historical Climatology Network (USHCN) and simulations from the North American Regional Climate Change Assessment Program (NARCCAP). This effort will serve to establish the baseline behavior of climate extremes, the

  11. A direct method for computing extreme value (Gumbel) parameters for gapped biological sequence alignments.

    Science.gov (United States)

    Quinn, Terrance; Sinkala, Zachariah

    2014-01-01

    We develop a general method for computing extreme value distribution (Gumbel, 1958) parameters for gapped alignments. Our approach uses mixture distribution theory to obtain associated BLOSUM matrices for gapped alignments, which in turn are used for determining significance of gapped alignment scores for pairs of biological sequences. We compare our results with parameters already obtained in the literature.

  12. Climate change impact on groundwater levels: ensemble modelling of extreme values

    Directory of Open Access Journals (Sweden)

    J. Kidmose

    2012-06-01

    Full Text Available This paper presents a first attempt to estimate future groundwater levels by applying extreme value statistics on predictions from a hydrological model. Climate for the future period, 2081–2100, are represented by projections from nine combinations of three global climate models and six regional climate models, and downscaled with two different methods. An integrated surface water/groundwater model is forced with precipitation, temperature, and evapotranspiration from the 18 model – and downscaling combinations. Extreme value analyses are performed on the hydraulic head changes from a control period (1991–2010 to the future period for the 18 combinations. Hydraulic heads for return periods of 21, 50 and 100 yr (T21–100 are estimated. Three uncertainty sources are evaluated; climate models, downscaling and extreme value statistics. Of these sources, downscaling dominates for the higher return periods of 50 and 100 yr, whereas uncertainty from climate models and downscaling are similar for lower return periods. Uncertainty from the extreme value statistics only contribute up to around 10% of the uncertainty from the three sources.

  13. Extreme value statistics analysis of fracture strengths of a sintered silicon nitride failing from pores

    Science.gov (United States)

    Chao, Luen-Yuan; Shetty, Dinesh K.

    1992-01-01

    Statistical analysis and correlation between pore-size distribution and fracture strength distribution using the theory of extreme-value statistics is presented for a sintered silicon nitride. The pore-size distribution on a polished surface of this material was characterized, using an automatic optical image analyzer. The distribution measured on the two-dimensional plane surface was transformed to a population (volume) distribution, using the Schwartz-Saltykov diameter method. The population pore-size distribution and the distribution of the pore size at the fracture origin were correllated by extreme-value statistics. Fracture strength distribution was then predicted from the extreme-value pore-size distribution, usin a linear elastic fracture mechanics model of annular crack around pore and the fracture toughness of the ceramic. The predicted strength distribution was in good agreement with strength measurements in bending. In particular, the extreme-value statistics analysis explained the nonlinear trend in the linearized Weibull plot of measured strengths without postulating a lower-bound strength.

  14. Central limit theorems for smoothed extreme value estimates of Poisson point processes boundaries

    CERN Document Server

    Girard, Stéphane

    2011-01-01

    In this paper, we give sufficient conditions to establish central limit theorems for boundary estimates of Poisson point processes. The considered estimates are obtained by smoothing some bias corrected extreme values of the point process. We show how the smoothing leads Gaussian asymptotic distributions and therefore pointwise confidence intervals. Some new unidimensional and multidimensional examples are provided.

  15. Implementing Extreme Value Analysis in a Geospatial Workflow for Storm Surge Hazard Assessment

    Science.gov (United States)

    Catelli, J.; Nong, S.

    2014-12-01

    Gridded data of 100-yr (1%) and 500-yr (0.2%) storm surge flood elevations for the United States, Gulf of Mexico, and East Coast are critical to understanding this natural hazard. Storm surge heights were calculated across the study area utilizing SLOSH (Sea, Lake, and Overland Surges from Hurricanes) model data for thousands of synthetic US landfalling hurricanes. Based on the results derived from SLOSH, a series of interpolations were performed using spatial analysis in a geographic information system (GIS) at both the SLOSH basin and the synthetic event levels. The result was a single grid of maximum flood elevations for each synthetic event. This project addresses the need to utilize extreme value theory in a geospatial environment to analyze coincident cells across multiple synthetic events. The results are 100-yr (1%) and 500-yr (0.2%) values for each grid cell in the study area. This talk details a geospatial approach to move raster data to SciPy's NumPy Array structure using the Python programming language. The data are then connected through a Python library to an outside statistical package like R to fit cell values to extreme value theory distributions and return values for specified recurrence intervals. While this is not a new process, the value behind this work is the ability to keep this process in a single geospatial environment and be able to easily replicate this process for other natural hazard applications and extreme event modeling.

  16. Analyzing solvency with extreme value theory: an application to the Spanish motor liability insurance market

    Directory of Open Access Journals (Sweden)

    María José Pérez-Fructuoso

    2010-04-01

    Full Text Available An accurate estimation of extreme claims is fundamental to assess solvency capital requirements (SCR established by Solvency II. Basing on the Extreme Value Theory (EVT, this paper performs a parametric estimation to fit the motor liability insurance historical datasets of two significant and representative companies operating within the Spanish market to a Generalized Pareto Distribution. We illustrate how EVT improves classical adjustments, as it considers outliers apart from mass risks, what leads to optimize the pricing decision-making and fix a risk transfer position.

  17. Non-parametric frequency analysis of extreme values for integrated disaster management considering probable maximum events

    Science.gov (United States)

    Takara, K. T.

    2015-12-01

    This paper describes a non-parametric frequency analysis method for hydrological extreme-value samples with a size larger than 100, verifying the estimation accuracy with a computer intensive statistics (CIS) resampling such as the bootstrap. Probable maximum values are also incorporated into the analysis for extreme events larger than a design level of flood control. Traditional parametric frequency analysis methods of extreme values include the following steps: Step 1: Collecting and checking extreme-value data; Step 2: Enumerating probability distributions that would be fitted well to the data; Step 3: Parameter estimation; Step 4: Testing goodness of fit; Step 5: Checking the variability of quantile (T-year event) estimates by the jackknife resampling method; and Step_6: Selection of the best distribution (final model). The non-parametric method (NPM) proposed here can skip Steps 2, 3, 4 and 6. Comparing traditional parameter methods (PM) with the NPM, this paper shows that PM often underestimates 100-year quantiles for annual maximum rainfall samples with records of more than 100 years. Overestimation examples are also demonstrated. The bootstrap resampling can do bias correction for the NPM and can also give the estimation accuracy as the bootstrap standard error. This NPM has advantages to avoid various difficulties in above-mentioned steps in the traditional PM. Probable maximum events are also incorporated into the NPM as an upper bound of the hydrological variable. Probable maximum precipitation (PMP) and probable maximum flood (PMF) can be a new parameter value combined with the NPM. An idea how to incorporate these values into frequency analysis is proposed for better management of disasters that exceed the design level. The idea stimulates more integrated approach by geoscientists and statisticians as well as encourages practitioners to consider the worst cases of disasters in their disaster management planning and practices.

  18. Extreme value laws for fractal intensity functions in dynamical systems: Minkowski analysis

    Science.gov (United States)

    Mantica, Giorgio; Perotti, Luca

    2016-09-01

    Typically, in the dynamical theory of extremal events, the function that gauges the intensity of a phenomenon is assumed to be convex and maximal, or singular, at a single, or at most a finite collection of points in phase-space. In this paper we generalize this situation to fractal landscapes, i.e. intensity functions characterized by an uncountable set of singularities, located on a Cantor set. This reveals the dynamical rôle of classical quantities like the Minkowski dimension and content, whose definition we extend to account for singular continuous invariant measures. We also introduce the concept of extremely rare event, quantified by non-standard Minkowski constants and we study its consequences to extreme value statistics. Limit laws are derived from formal calculations and are verified by numerical experiments. Dedicated to the memory of Joseph Ford, on the twentieth anniversary of his departure.

  19. An extreme value model for maximum wave heights based on weather types

    Science.gov (United States)

    Rueda, Ana; Camus, Paula; Méndez, Fernando J.; Tomás, Antonio; Luceño, Alberto

    2016-02-01

    Extreme wave heights are climate-related events. Therefore, special attention should be given to the large-scale weather patterns responsible for wave generation in order to properly understand wave climate variability. We propose a classification of weather patterns to statistically downscale daily significant wave height maxima to a local area of interest. The time-dependent statistical model obtained here is based on the convolution of the stationary extreme value model associated to each weather type. The interdaily dependence is treated by a climate-related extremal index. The model's ability to reproduce different time scales (daily, seasonal, and interannual) is presented by means of its application to three locations in the North Atlantic: Mayo (Ireland), La Palma Island, and Coruña (Spain).

  20. Effect of pH values on the extracellular polysaccharide secreted by Acidithiobacillus ferrooxidans during chalcopyrite bioleaching

    Institute of Scientific and Technical Information of China (English)

    Run-lan Yu; Jing Liu; Jian-xi Tan; Wei-min Zeng; Li-juan Shi; Guo-hua Gu; Wen-qing Qin; Guan-zhou Qiu

    2014-01-01

    The pH value plays an important role in the bioleaching of sulphide minerals. The effect of pH values on the extracellular poly-saccharide secreted by Acidithiobacillus ferrooxidans was investigated in different phases of bacterial growth during chalcopyrite bioleach-ing. It is found that extracellular polysaccharide secretion from the cells attached to chalcopyrite is more efficiently than that of the free cells in the bioleaching solution. Three factors, pH values, the concentration of soluble metal ions, and the bacterial growth and metabolism, affect extracellular polysaccharide secretion in the free cells, and are related to the bacterial growth phase. Extracellular polysaccharide secretion from the attached cells is mainly dependent on the pH value of the bacterial culture.

  1. On the identification of Dragon Kings among extreme-valued outliers

    Directory of Open Access Journals (Sweden)

    M. Riva

    2013-07-01

    Full Text Available Extreme values of earth, environmental, ecological, physical, biological, financial and other variables often form outliers to heavy tails of empirical frequency distributions. Quite commonly such tails are approximated by stretched exponential, log-normal or power functions. Recently there has been an interest in distinguishing between extreme-valued outliers that belong to the parent population of most data in a sample and those that do not. The first type, called Gray Swans by Nassim Nicholas Taleb (often confused in the literature with Taleb's totally unknowable Black Swans, is drawn from a known distribution of the tails which can thus be extrapolated beyond the range of sampled values. However, the magnitudes and/or space–time locations of unsampled Gray Swans cannot be foretold. The second type of extreme-valued outliers, termed Dragon Kings by Didier Sornette, may in his view be sometimes predicted based on how other data in the sample behave. This intriguing prospect has recently motivated some authors to propose statistical tests capable of identifying Dragon Kings in a given random sample. Here we apply three such tests to log air permeability data measured on the faces of a Berea sandstone block and to synthetic data generated in a manner statistically consistent with these measurements. We interpret the measurements to be, and generate synthetic data that are, samples from α-stable sub-Gaussian random fields subordinated to truncated fractional Gaussian noise (tfGn. All these data have frequency distributions characterized by power-law tails with extreme-valued outliers about the tail edges.

  2. Convergence of Extreme Value Statistics in a Two-Layer Quasi-Geostrophic Atmospheric Model

    Directory of Open Access Journals (Sweden)

    Vera Melinda Gálfi

    2017-01-01

    Full Text Available We search for the signature of universal properties of extreme events, theoretically predicted for Axiom A flows, in a chaotic and high-dimensional dynamical system. We study the convergence of GEV (Generalized Extreme Value and GP (Generalized Pareto shape parameter estimates to the theoretical value, which is expressed in terms of the partial information dimensions of the attractor. We consider a two-layer quasi-geostrophic atmospheric model of the mid-latitudes, adopt two levels of forcing, and analyse the extremes of different types of physical observables (local energy, zonally averaged energy, and globally averaged energy. We find good agreement in the shape parameter estimates with the theory only in the case of more intense forcing, corresponding to a strong chaotic behaviour, for some observables (the local energy at every latitude. Due to the limited (though very large data size and to the presence of serial correlations, it is difficult to obtain robust statistics of extremes in the case of the other observables. In the case of weak forcing, which leads to weaker chaotic conditions with regime behaviour, we find, unsurprisingly, worse agreement with the theory developed for Axiom A flows.

  3. Effect of pH value on electromagnetic loss properties of Co-Zn ferrite prepared via coprecipitation method

    Science.gov (United States)

    Huang, Xiaogu; Zhang, Jing; Wang, Wei; Sang, Tianyi; Song, Bo; Zhu, Hongli; Rao, Weifeng; Wong, Chingping

    2016-05-01

    In this paper, the cobalt zinc ferrite was prepared by coprecipitation method at different pH conditions. The influence of pH values on the coprecipitation reaction was theoretically analyzed at first. The calculated results showed that the pH values should be controlled in the range of 9-11 to form the stable precipitation. The XRD investigation was used to further confirm the formation of the composite on specific pH values. In addition, the morphological study revealed that the average particle size of the composite decreased from 40 nm to 30 nm when the pH value increased from 9-11. The variation of microstructure plays a critical role in controlling the electromagnetic properties. From the electromagnetic analysis, the dielectric loss factor was 0.02-0.07 and magnetic loss factor was 0.2-0.5 for the composite synthesized at pH of 9, which presents dramatically improved dielectric loss and magnetic loss properties than the samples prepared at pH of 10 and 11. The as-prepared cobalt zinc ferrite are highly promising to be used as microwave absorption materials.

  4. Extreme values of relative distances for spacecraft in elliptic displaced orbits

    Science.gov (United States)

    Wang, Wei; Mengali, Giovanni; Quarta, Alessandro A.; Yuan, Jianping

    2016-08-01

    This paper provides a framework to obtain a semi-analytical approximation of extreme values of relative distances between two spacecraft that cover elliptic displaced orbits. The relative motion is described in the rotating reference frame of the chief spacecraft and is parameterized with a new set of displaced orbital elements. The extreme values of the radial, along-track and cross-track distance are analytically evaluated (as roots of suitable algebraic equations) both for quasi-periodic orbits in the incommensurable case, and for periodic orbits in the 1:1 commensurable case. In particular, in the 1:1 commensurable case a Fourier series expansion is used to obtain a time-explicit expression of the relative motion. Finally, some illustrative examples are presented to validate the correctness of the proposed method.

  5. Small-sample likelihood inference in extreme-value regression models

    CERN Document Server

    Ferrari, Silvia L P

    2012-01-01

    We deal with a general class of extreme-value regression models introduced by Barreto- Souza and Vasconcellos (2011). Our goal is to derive an adjusted likelihood ratio statistic that is approximately distributed as \\c{hi}2 with a high degree of accuracy. Although the adjusted statistic requires more computational effort than its unadjusted counterpart, it is shown that the adjustment term has a simple compact form that can be easily implemented in standard statistical software. Further, we compare the finite sample performance of the three classical tests (likelihood ratio, Wald, and score), the gradient test that has been recently proposed by Terrell (2002), and the adjusted likelihood ratio test obtained in this paper. Our simulations favor the latter. Applications of our results are presented. Key words: Extreme-value regression; Gradient test; Gumbel distribution; Likelihood ratio test; Nonlinear models; Score test; Small-sample adjustments; Wald test.

  6. Characterizing detection thresholds using extreme value theory in compressive noise radar imaging

    Science.gov (United States)

    Shastry, Mahesh C.; Narayanan, Ram M.; Rangaswamy, Muralidhar

    2013-05-01

    An important outcome of radar signal processing is the detection of the presence or absence of target reflections at each pixel location in a radar image. In this paper, we propose a technique based on extreme value theory for characterizing target detection in the context of compressive sensing. In order to accurately characterize target detection in radar systems, we need to relate detection thresholds and probabilities of false alarm. However, when convex optimization algorithms are used for compressive radar imaging, the recovered signal may have unknown and arbitrary probability distributions. In such cases, we resort to Monte Carlo simulations to construct empirical distributions. Computationally, this approach is impractical for computing thresholds for low probabilities of false alarm. We propose to circumvent this problem by using results from extreme-value theory.

  7. Measuring daily Value-at-Risk of SSEC index: A new approach based on multifractal analysis and extreme value theory

    Science.gov (United States)

    Wei, Yu; Chen, Wang; Lin, Yu

    2013-05-01

    Recent studies in the econophysics literature reveal that price variability has fractal and multifractal characteristics not only in developed financial markets, but also in emerging markets. Taking high-frequency intraday quotes of the Shanghai Stock Exchange Component (SSEC) Index as example, this paper proposes a new method to measure daily Value-at-Risk (VaR) by combining the newly introduced multifractal volatility (MFV) model and the extreme value theory (EVT) method. Two VaR backtesting techniques are then employed to compare the performance of the model with that of a group of linear and nonlinear generalized autoregressive conditional heteroskedasticity (GARCH) models. The empirical results show the multifractal nature of price volatility in Chinese stock market. VaR measures based on the multifractal volatility model and EVT method outperform many GARCH-type models at high-risk levels.

  8. A conditional extreme value theory approach in value-at-risk forecasting: Evidence from Southeastern Europe and USA market

    Directory of Open Access Journals (Sweden)

    Totić Selena

    2015-01-01

    Full Text Available As a consequence of the recent financial crisis, the adequacy of different Value-at-Risk (VaR methodologies was heavily questioned. Current practice in VaR assessment relies on modeling the whole distribution of returns. As an alternative, in this paper we model tail behavior of returns, and thus VaR, using conditional Extreme Value Theory (EVT, which combines EVT and GARCH methodology. Moreover, we examine the performance of conditional EVT with the daily returns of seven stock market indices, of which six are from Southeastern Europe (BelexLine, BET, BUX, CROBEX, SBITOP, SOFIX from the period of September 2004 - April 2013, and one from USA market (Standard&Poors 500 Index from the period January 1998 - April 2013. Backtesting of historical daily returns proves that conditional EVT model gives good predictions for all indices and for all confidence levels.

  9. New estimators of the extreme value index under random right censoring, for heavy-tailed distributions

    OpenAIRE

    Worms, Julien; Worms, Rym

    2014-01-01

    International audience; This paper presents new approaches for the estimation of the extreme value index in the framework of randomly censored (from the right) samples, based on the ideas of Kaplan-Meier integration and the synthetic data approach of S.Leurgans (1987). These ideas are developed here in the heavy tail case and for the adaptation of the Hill estimator, for which the consistency is proved under first order conditions. Simulations show good performance of the two approaches, with...

  10. On holomorphic functions with certain extremal properties of its absolute values

    Directory of Open Access Journals (Sweden)

    Dieter Schmersau

    1981-01-01

    Full Text Available This paper is concerned with a special class of holomorphic functions with extremal properties of its absolute values on arbitrary closed line segments in the complex plane. The main result is a geometrical characterization of the functions z→eaz+b, z→(az+bn and z→(az+bα+iβ with a,b,∈ℂ, α,β∈ℝ, n∈ℤ.

  11. Decadal oscillations and extreme value distribution of river peak flows in the Meuse catchment

    Science.gov (United States)

    De Niel, Jan; Willems, Patrick

    2017-04-01

    In flood risk management, flood probabilities are often quantified through Generalized Pareto distributions of river peak flows. One of the main underlying assumptions is that all data points need to originate from one single underlying distribution (i.i.d. assumption). However, this hypothesis, although generally assumed to be correct for variables such as river peak flows, remains somehow questionable: flooding might indeed be caused by different hydrological and/or meteorological conditions. This study confirms these findings from previous research by showing a clear indication of the link between atmospheric conditions and flooding for the Meuse river in The Netherlands: decadal oscillations of river peak flows can (at least partially) be attributed to the occurrence of westerly weather types. The study further proposes a method to take this correlation between atmospheric conditions and river peak flows into account when calibrating an extreme value distribution for river peak flows. Rather than calibrating one single distribution to the data and potentially violating the i.i.d. assumption, weather type depending extreme value distributions are derived and composed. The study shows that, for the Meuse river in The Netherlands, such approach results in a more accurate extreme value distribution, especially with regards to extrapolations. Comparison of the proposed method with a traditional extreme value analysis approach and an alternative model-based approach for the same case study shows strong differences in the peak flow extrapolation. The design-flood for a 1,250 year return period is estimated at 4,800 m3s-1 for the proposed method, compared with 3,450 m3s-1 and 3,900 m3s-1 for the traditional method and a previous study. The methods were validated based on instrumental and documentary flood information of the past 500 years.

  12. A theory of the cancer age-specific incidence data based on extreme value distributions

    Science.gov (United States)

    Soto-Ortiz, Luis; Brody, James P.

    2012-03-01

    The incidence of cancers varies with age, if normalized this is called the age-specific incidence. A mathematical model that describes this variation should provide a better understanding of how cancers develop. We suggest that the age-specific incidence should follow an extreme value distribution, based on three widely accepted assumptions: (1) a tumor develops from a single cell, (2) many potential tumor progenitor cells exist in a tissue, and (3) cancer is diagnosed when the first of these many potential tumor cells develops into a tumor. We tested this by comparing the predicted distribution to the age-specific incidence data for colon and prostate carcinomas collected by the Surveillance, Epidemiology and End Results network of 17 cancer registries. We found that colon carcinoma age-specific incidence data is consistent with an extreme value distribution, while prostate carcinomas age-specific incidence data generally follows the distribution. This model indicates that both colon and prostate carcinomas only occur in a subset of the population (22% for prostate and 13.5% for colon.) Because of their very general nature, extreme value distributions might be applicable to understanding other chronic human diseases.

  13. Study on Impacts of pH Value on Paulownia Wood Color

    Institute of Scientific and Technical Information of China (English)

    CHANG Delong; SONG Zhanqian; HU Weihua; HUANG Wenhao; LI Fuhai; ZHANG Yunling

    2006-01-01

    Impacts of acid and alkali on paulownia wood are studied, and the effects of weak alkali solution on stain prevention of paulownia wood are tested and analyzed. It shows that pH value affects paulownia wood color, and that white value of paulownia wood is prone to decrease and chromatism rises under acidity condition. Under alkalescence condition, whiteness of paulownia wood rises and chromatism decreases, color and luster obviously tend to be bright. The alkali solution with concentration of 0.25% can promote the penetrability of paulownia wood, dissolve some extractives containing stain precursor chemicals, strengthen stain prevention of paulownia wood, but can not contaminate board surface. Anti-stain reagent has effect on prevention stain of paulownia wood, but only using it for controlling paulownia wood stain will induce stain-returning phenomenon. Using both weak alkali solution and anti-stain reagent has better effect than just using reagent, the treatment by concentration of 0.25% weak alkali solution with anti-stain reagent can make controlling effect even both inside and outside.

  14. Electrochemical performance of nano-scale β-Ni(OH)2 prepared at different transformations of pH value

    Institute of Scientific and Technical Information of China (English)

    ZHAO Li; ZHANG Li-jun; HAN Xi-jiang; ZHANG Cui-fen

    2008-01-01

    The influence of transforming pH values on the electrochemical performance of nano-scale Ni(OH)2was analyzed. The measurement results of XRD indicate that the nano-scale Ni (OH)2 prepared at different transformations of pH value is β( Ⅱ )-phase with different crystal lattice parameters. Cyclic voltammograms (CV) and electrochemical impedance spectroscopy(EIS) measurement results show that transformations of pH value affect the proton diffusion coefficient (D) and charge-transfer resistance (Rct) of the material. The simu-lation of cell experiment shows that the sample prepared at a pH of 10. 1 exhibits the maximum specific capacity(327. 8 mAh/g) and higher discharge platform, the discharge performance of electrodes depends on both D and Rct, so the kinetics characteristics that electrodes reaction is controlled by both mass-transfer step and charge-transfer step are put forward.

  15. Extreme Value Statistical Characterization of Time Domain Pulse-to-Pulse Measurements

    CERN Document Server

    AUTHOR|(SzGeCERN)712364; Arpaia, Pasquale; Martino, Michele

    2015-01-01

    An analytical method, based on Extreme Value Theory (EV T), for predicting the worst case repeatability of time domain pulse-to-pulse measurements, modeled as independent and identically distributed random variables, is proposed. The method allows the use of the noise level of a measurement system for predicting the upcoming peak values over a given number of independent observations. The proposed analytical model is compared against simulated distributions generated in Matlab, highlighting satisfying match for any sample size.The simulations are based on a case study on the characterization of a pulsed power supply for the klystron modulators of the Compact LInear Collider (CLIC) under study at CERN.

  16. Freezing transitions and extreme values: random matrix theory, ζ (1/2 + it) and disordered landscapes.

    Science.gov (United States)

    Fyodorov, Yan V; Keating, Jonathan P

    2014-01-28

    We argue that the freezing transition scenario, previously conjectured to occur in the statistical mechanics of 1/f-noise random energy models, governs, after reinterpretation, the value distribution of the maximum of the modulus of the characteristic polynomials pN(θ) of large N×N random unitary (circular unitary ensemble) matrices UN; i.e. the extreme value statistics of pN(θ) when N → ∞. In addition, we argue that it leads to multi-fractal-like behaviour in the total length μN(x) of the intervals in which |pN(θ)|>N(x), x>0, in the same limit. We speculate that our results extend to the large values taken by the Riemann zeta function ζ(s) over stretches of the critical line s = 1/2 + it of given constant length and present the results of numerical computations of the large values of ζ(1/2 + it). Our main purpose is to draw attention to the unexpected connections between these different extreme value problems.

  17. Freezing transitions and extreme values: random matrix theory, and disordered landscapes

    Science.gov (United States)

    Fyodorov, Yan V.; Keating, Jonathan P.

    2014-01-01

    We argue that the freezing transition scenario, previously conjectured to occur in the statistical mechanics of 1/f-noise random energy models, governs, after reinterpretation, the value distribution of the maximum of the modulus of the characteristic polynomials pN(θ) of large N×N random unitary (circular unitary ensemble) matrices UN; i.e. the extreme value statistics of pN(θ) when . In addition, we argue that it leads to multi-fractal-like behaviour in the total length μN(x) of the intervals in which |pN(θ)|>Nx,x>0, in the same limit. We speculate that our results extend to the large values taken by the Riemann zeta function ζ(s) over stretches of the critical line of given constant length and present the results of numerical computations of the large values of ). Our main purpose is to draw attention to the unexpected connections between these different extreme value problems. PMID:24344336

  18. Biohydrogen production from household solid waste (HSW) at extreme-thermophilic temperature (70 degrees C) - Influence of pH and acetate concentration

    DEFF Research Database (Denmark)

    Liu, Dawei; Min, Booki; Angelidaki, Irini

    2008-01-01

    pH of 7.0. Acetate was proved to be inhibiting the dark fermentation process at neutral pH, which indicates that the inhibition was caused by total acetate concentration not by undissociated acetate. Initial inhibition was detected at acetate concentration of 50 mM, while the hydrogen fermentation......Hydrogen production from household solid waste (HSW) was performed via dark fermentation by using an extreme-thermophilic mixed culture, and the effect of pH and acetate on the biohydrogen production was investigated. The highest hydrogen production yield was 257 +/- 25 mL/gVS(added) at the optimum...

  19. National scale multivariate extreme value modelling of waves, winds and sea levels

    Directory of Open Access Journals (Sweden)

    Gouldby Ben

    2016-01-01

    Full Text Available It has long been recognised that extreme coastal flooding can arise from the joint occurrence of extreme waves, winds and sea levels. The standard simplified joint probability approach used in England and Wales can result in an underestimation of flood risk unless correction factors are applied. This paper describes the application of a state-of-the-art multivariate extreme value model to offshore winds, waves and sea levels around the coast of England. The methodology overcomes the limitations of the traditional method. The output of the new statistical analysis is a Monte-Carlo (MC simulation comprising many thousands of offshore extreme events and it is necessary to translate all of these events into overtopping rates for use as input to flood risk assessments. It is computationally impractical to transform all of these MC events from the offshore to the nearshore. Computationally efficient statistical emulators of the SWAN wave transformation model have therefore been constructed. The emulators translate the thousands of MC events offshore. Whilst the methodology has been applied for national flood risk assessment, it has the potential to be implemented for wider use, including climate change impact assessment, nearshore wave climates for detailed local assessments and coastal flood forecasting.

  20. Using Extreme Value Theory for Determining the Probability of Carrington-Like Solar Flares

    CERN Document Server

    Elvidge, Sean

    2016-01-01

    Space weather events can negatively affect satellites, the electricity grid, satellite navigation systems and human health. As a consequence, extreme space weather has been added to the UK and other national risk registers. However, by their very nature, extreme events occur rarely and statistical methods are required to determine the probability of occurrence solar storms. Space weather events can be characterised by a number of natural phenomena such as X-ray (solar) flares, solar energetic particle (SEP) fluxes, coronal mass ejections and various geophysical indices (Dst, Kp, F10.7). Here we use extreme value theory (EVT) to investigate the probability of extreme solar flares. Previous work has suggested that the distribution of solar flares follows a power law. However such an approach can lead to overly "fat-tails" in the probability distribution function and thus to an under estimation of the return time of such events. Using EVT and GOES X-ray flux data we find that the expected 150 year return level i...

  1. Tolerance of Physocypria kraepelini (Crustacean, Ostracoda) to water-borne ammonia, phosphate and pH value

    Institute of Scientific and Technical Information of China (English)

    YU Na; CHEN Shimei; LI Erchao; CHEN Jiayan; CHEN Liqiao

    2009-01-01

    This study evaluated the median lethal concentration (LC_(50)) and safe concentration of water-borne ammonia,phosphate and pH value on Physocypria kraepelini,a freshwater Ostracoda with a static renewal test system.The results indicated that the LC_(50) values of ammonia for P.kraepelini were 1026.71,859.98,771.79 and 583.82 mg/L at 24,48,72 and 96 h exposure,respectively,and the safe concentration range of ammonia for the long-term survival of P.kraepelini was less than 58.38 mg/L.Finally,the safe range of pH value for the survival of P.kraepelini was from 6.59 to 7.61.P.kraepelini has a high tolerance to ammonia,phosphate and pH value which are the main environmental factors in the serious eutrophication water.

  2. Kinetics of ferrous iron oxidation by batch and continuous cultures of thermoacidophilic Archaea at extremely low pH of 1.1–1.3

    NARCIS (Netherlands)

    Gonzalez-Contreras, P.A.; Weijma, J.; Buisman, C.J.N.

    2012-01-01

    The extreme acid conditions required for scorodite (FeAsO4·2H2O) biomineralization (pH below 1.3) are suboptimal for growth of most thermoacidophilic Archaea. With the objective to develop a continuous process suitable for biomineral production, this research focuses on growth kinetics of

  3. Factors determining growth and vertical distribution of planktonic algae in extremely acidic mining lakes (pH 2.7)

    Science.gov (United States)

    Bissinger, Vera

    2003-04-01

    In this thesis, I investigated the factors influencing the growth and vertical distribution of planktonic algae in extremely acidic mining lakes (pH 2-3). In the focal study site, Lake 111 (pH 2.7; Lusatia, Germany), the chrysophyte, Ochromonas sp., dominates in the upper water strata and the chlorophyte, Chlamydomonas sp., in the deeper strata, forming a pronounced deep chlorophyll maximum (DCM). Inorganic carbon (IC) limitation influenced the phototrophic growth of Chlamydomonas sp. in the upper water strata. Conversely, in deeper strata, light limited its phototrophic growth. When compared with published data for algae from neutral lakes, Chlamydomonas sp. from Lake 111 exhibited a lower maximum growth rate, an enhanced compensation point and higher dark respiration rates, suggesting higher metabolic costs due to the extreme physico-chemical conditions. The photosynthetic performance of Chlamydomonas sp. decreased in high-light-adapted cells when IC limited. In addition, the minimal phosphorus (P) cell quota was suggestive of a higher P requirement under IC limitation. Subsequently, it was shown that Chlamydomonas sp. was a mixotroph, able to enhance its growth rate by taking up dissolved organic carbon (DOC) via osmotrophy. Therefore, it could survive in deeper water strata where DOC concentrations were higher and light limited. However, neither IC limitation, P availability nor in situ DOC concentrations (bottom-up control) could fully explain the vertical distribution of Chlamydomonas sp. in Lake 111. Conversely, when a novel approach was adopted, the grazing influence of the phagotrophic phototroph, Ochromonas sp., was found to exert top-down control on its prey (Chlamydomonas sp.) reducing prey abundance in the upper water strata. This, coupled with the fact that Chlamydomonas sp. uses DOC for growth, leads to a pronounced accumulation of Chlamydomonas sp. cells at depth; an apparent DCM. Therefore, grazing appears to be the main factor influencing the

  4. Multivariate extreme value analysis of storm surges in SCS on peak over threshold method

    Directory of Open Access Journals (Sweden)

    Y. Luo

    2015-11-01

    Full Text Available We use a novel statistical approach-MGPD to analyze the joint probability distribution of storm surge events at two sites and present a warning method for storm surges at two adjacent positions in Beibu Gulf, using the sufficiently long field data on surge levels at two sites. The methodology also develops the procedure of application of MGPD, which includes joint threshold and Monte Carlo simulation, to handle multivariate extreme values analysis. By comparing the simulation result with analytic solution, it is shown that the relative error of the Monte Carlo simulation is less than 8.6 %. By running MGPD model based on long data at Beihai and Dongfang, the simulated potential surge results can be employed in storm surge warnings of Beihai and joint extreme water level predictions of two sites.

  5. Hydrogel/fiber optic sensor for distributed measurement of humidity and pH value

    Science.gov (United States)

    MacLean, Alistair; Michie, W. Craig; Pierce, S. Gareth; Thursby, Graham; Culshaw, Brian; Moran, Chris; Graham, Neil B.

    1998-07-01

    The combination of chemically sensitive, swellable polymer materials with novel optical fiber cable designs to transduce the swelling activity into microbend loss enables a simple yet powerful sensor to be produced. Interrogating such cables with standard optical time domain reflectoctrometry (OTDR) instruments allows particular chemicals of interest to be detected and located along a cable which may extend to several kilometers. We report here on a sensor cable which uses a water swellable material, a hydrogel, to detect positions of water ingress, relative humidity level or pH value. In direct water ingress tests, wet sensor lengths as small as 5 cm in several hundreds of meters have been detected using conventional OTDRs. Following a review of the sensor design, we present the results of an investigation of the mechanical interaction between the hydrogel polymer and the optical fiber within the sensor. The behavior of the sensor is then characterized within environments of different relative humidity levels from 70 percent to 100 percent at temperatures ranging from 0 to 60 degrees C. The sensor was initially designed for applications within civil engineering but can be applied to a much broader range of measurement requirements, for example soil moisture measurement. We will report details on experimental observations on concrete cure within reinforcing tendon ducts and soil humidity measurements within different soil types.

  6. Strain rate dependency of oceanic intraplate earthquake b-values at extremely low strain rates

    Science.gov (United States)

    Sasajima, Ryohei; Ito, Takeo

    2016-06-01

    We discovered a clear positive dependence of oceanic intraplate earthquake (OCEQ) b-values on the age of the oceanic lithosphere. OCEQ b-values in the youngest (20 Ma) oceanic lithosphere exceed 1.5, which is significantly higher than the average worldwide earthquake b-value (around 1.0). On the other hand, the b-value of intraplate earthquakes in the Ninety East-Sumatra orogen, where oceanic lithosphere has an anomalously higher strain rate compared with normal oceanic lithosphere, is 0.93, which is significantly lower than the OCEQ b-value (about 1.9) with the same age (50-110 Ma). Thus, the variation in b-values relates to the strain rate of the oceanic lithosphere and is not caused by a difference in thermal structure. We revealed a negative strain rate dependency of the b-value at extremely low strain rates (1.5) in oceanic lithosphere >20 Ma old imply that future improvement in seismic observation will capture many smaller magnitude OCEQs, which will provide valuable information on the evolution of the oceanic lithosphere and the driving mechanism of plate tectonics.

  7. Effect of pH Value on Stress Corrosion Cracking of X70 Pipeline Steel in Acidic Soil Environment

    Institute of Scientific and Technical Information of China (English)

    Zhiyong LIU; Cuiwei DU; Xin ZHANG; Fuming WANG; Xiaogang LI

    2013-01-01

    The effect of pH value on the stress corrosion cracking (SCC) of API X70 pipeline steel in simulated acidic soil solutions was investigated by using slow strain rate test,electrochemical polarization curves,electrochemical impedance spectroscopy,and scanning electron microscopy.pH plays an important role in the susceptibility and electrochemical mechanism of SCC.The pH higher than 5 has no significant effect on electrochemical processes.By contrast,the pH lower than 5 intensifies cathodic hydrogen evolution reactions,thus increasing the cathodic current and corrosion potential.Under different pH values,the SCC mechanism of X70 pipeline steel varies among anodic dissolution (AD),hydrogen embrittlement (HE),and the combination of AD and HE (AD + HE) with variations of applied potential.At-850 mVSCE,the SCC mechanism is HE if pH is less than 4 or AD + HE if pH value is more positive.

  8. Extreme Value Predictions using Monte Carlo Simulations with Artificially Increased Load Spectrum

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher

    2011-01-01

    In the analysis of structures subjected to stationary stochastic load processes the mean out-crossing rate plays an important role as it can be used to determine the extreme value distribution of any response, usually assuming that the sequence of mean out-crossings can be modelled as a Poisson p...... be scaled down to its actual value. In the present paper the usefulness of this approach is investigated, considering problems related to wave loads on marine structures. Here the load scale parameter is conveniently taken as the square of the significant wave height.......In the analysis of structures subjected to stationary stochastic load processes the mean out-crossing rate plays an important role as it can be used to determine the extreme value distribution of any response, usually assuming that the sequence of mean out-crossings can be modelled as a Poisson...... to be valid in the Monte Carlo simulations, making it possible to increase the out-crossing rates and thus reduce the necessary length of the time domain simulations by applying a larger load spectrum than relevant from a design point of view. The mean out-crossing rate thus obtained can then afterwards...

  9. Extreme value predictions and critical wave episodes for marine structures by FORM

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher

    2008-01-01

    The aim of the present paper is to advocate for a very effective stochastic procedure, based on the First Order Reliability Method (FORM), for extreme value predictions related to wave induced loads. Three different applications will be illustrated. The first deals with a jack-up rig where second...... order stochastic waves are included in the analysis. The second application is parametric roll motions of ships. Finally, the motion of a TLP floating foundation for an offshore wind turbine is analysed taking into account large motions....

  10. Extreme value predictions and critical wave episodes for marine structures by FORM

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher

    2007-01-01

    The aim of the present paper is to advocate for a very effective stochastic procedure, based on the First Order Reliability Method (FORM), for extreme value predictions related to wave induced loads. Three different applications will be illustrated. The first deals with a jack-up rig where second...... order stochastic waves are included in the analysis. The second application is parametric roll motions of ships. Finally, the motion of a TLP floating foundation for an offshore wind turbine is analysed taking into account large motions....

  11. Extreme value problems without calculus: a good link with geometry and elementary maths

    Science.gov (United States)

    Ganci, Salvatore

    2016-11-01

    Some classical examples of problem solving, where an extreme value condition is required, are here considered and/or revisited. The search for non-calculus solutions appears pedagogically useful and intriguing as shown through a rich literature. A teacher, who teaches both maths and physics, (as happens in Italian High schools) can find in these kinds of problems a mind stimulating exercise compared with the standard solution obtained by the differential calculus. A good link between the geometric and analytical explanations is so established.

  12. Comparison of regional index flood estimation procedures based on the extreme value type I distribution

    DEFF Research Database (Denmark)

    Kjeldsen, Thomas Rodding; Rosbjerg, Dan

    2002-01-01

    A comparison of different methods for estimating T-year events is presented, all based on the Extreme Value Type I distribution. Series of annual maximum flood from ten gauging stations at the New Zealand South island have been used. Different methods of predicting the 100-year event...... considered applying either a log-linear relationship between at-site mean annual flood and catchment characteristics or a direct log-linear relationship between 100-year events and catchment characteristics. Comparison of the results shows that the existence of at-site measurements significantly diminishes...

  13. Thymic selection of T-cell receptors as an extreme value problem

    CERN Document Server

    Kosmrlj, Andrej; Kardar, Mehran; Shakhnovich, Eugene I

    2009-01-01

    T lymphocytes (T cells) orchestrate adaptive immune responses upon activation. T cell activation requires sufficiently strong binding of T cell receptors (TCRs) on their surface to short peptides (p) derived from foreign proteins, which are bound to major histocompatibility (MHC) gene products (displayed on antigen presenting cells). A diverse and self-tolerant T cell repertoire is selected in the thymus. We map thymic selection processes to an extreme value problem and provide an analytic expression for the amino acid compositions of selected TCRs (which enable its recognition functions).

  14. Investigations into aggregate formation with oppositely charged oil-in-water emulsions at different pH values.

    Science.gov (United States)

    Maier, Christiane; Zeeb, Benjamin; Weiss, Jochen

    2014-05-01

    The pH-dependent formation and stability of food-grade heteroaggregates from oppositely charged oil-in-water (O/W) emulsions was investigated. After screening suitable emulsifiers, 10% (w/w) oil in-water emulsions (d32≈1 μm) were prepared at pH 3-7 using a positively charged emulsifier (Na-lauroyl-l-arginine ethyl ester; LAE) and four negatively charged ones (citric esters of mono- and diglycerides, soy lecithin, sugar beet pectin, and Quillaja saponin). The oppositely charged emulsions were then combined at constant pH values at a volume flow rate ratio of 1:1. Emulsions and heteroaggregates were characterized by their surface charge, particle size distribution and microstructure using dynamic and static light scattering as well as confocal laser scanning microscopy. The emulsifier type was found to greatly influence the type of heteroaggregates formed, as well as the pH value, specifically in combined LAE/Quillaja saponin emulsions. Larger aggregates particularly were formed with increasing pH values (2.71±1.21 to 46.53±4.30 μm from pH 3 to 7, respectively), while LAE/pectin aggregates appeared not to be affected by pH over the full pH range investigated (3.80±2.89 to 3.94±2.78 μm from pH 3 to 7, respectively). Our study thus provides valuable first insights into the mechanism of the formation of food-grade heteroaggregates for later use in food systems. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Individual Traits, Personal Values, and Conflict Resolution in an Isolated, Confined, Extreme Environment.

    Science.gov (United States)

    Corneliussen, Jesper G; Leon, Gloria R; Kjærgaard, Anders; Fink, Birgit A; Venables, Noah C

    2017-06-01

    The study of personality traits, personal values, and the emergence of conflicts within groups performing in an isolated, confined, and extreme environment (ICE) may provide insights helpful for the composition and support of space crews for long duration missions. Studied pre/post and over the 2-yr period of the investigation were 10 Danish military personnel deployed to stations in Greenland on a 26-mo staggered rotation. Subjects completed the NEO PI-R, Triarchic Psychopathy Measure, and Portrait Values Questionnaire, and participated in structured interviews. During deployment, questionnaires were completed biweekly and a cognitive function test once a month. Personality findings indicated a generally well-adjusted group, above average in positive personality traits [Conscientiousness T-score = 59.4 (11.41); Agreeableness T-score = 54.4 (9.36)] and boldness. Personal values of benevolence and self-direction were highly rated. The decision when to "pick sides" and intervene during disagreements between group members was viewed as an important component of conflict resolution. There were no changes in positive/negative affect or cognitive function over the annual light/dark cycle. The personal values of group members appear highly compatible for living in a small group ICE environment for an extended period. Disagreements between group members impact the functioning of the entire group, particularly in regard to decisions whether to support one of the individuals or let the argument run its course. Extended training in strategies for conflict resolution are needed in planning for future long duration missions to avoid fault lines forming within the group.Corneliussen JG, Leon GR, Kjærgaard A, Fink BA, Venables NC. Individual traits, personal values, and conflict resolution in an isolated, confined, extreme environment. Aerosp Med Hum Perform. 2017; 88(6):535-543.

  16. Tendencies of extreme values on rainfall and temperature and its relationship with teleconnection patterns

    Science.gov (United States)

    Taboada, J. J.; Cabrejo, A.; Guarin, D.; Ramos, A. M.

    2009-04-01

    It is now very well established that yearly averaged temperatures are increasing due to anthropogenic climate change. In the area of Galicia (NW Spain) this trend has also been determined. Rainfall does not show a clear tendency in its yearly accumulated values. The aim of this work is to study different extreme indices of rainfall and temperatures analysing variability and possible trends associated to climate change. Station data for the study was provided by the CLIMA database of the regional government of Galicia (NW Spain). The definition of the extreme indices was taken from the joint CCl/CLIVAR/JCOMM Expert Team (ET) on Climate Change Detection and Indices (ETCCDI) This group has defined a set of standard extreme values to simplify intercomparison of data from different regions of the world. For the temperatures in the period 1960-2006, results show a significant increase of the number of days with maximum temperatures above the 90th percentile. Furthermore, a significant decrease of the days with maximum temperatures below the 10th percentile has been found. The tendencies of minimum temperatures are reverse: fewer nights with minimum temperatures below 10th percentile, and more with minimum temperatures above 90th percentile. Those tendencies can be observed all over the year, but are more pronounced in summer. This trend is expected to continue in the next decades because of anthropogenic climate change. We have also calculated the relationship between the above mentioned extreme values and different teleconnection patterns appearing in the North Atlantic area. Results show that local tendencies are associated with trends of EA (Eastern Atlantic) and SCA (Scandinavian) patterns. NAO (North Atlantic Oscillation) has also some relationship with these tendencies, but only related with cold days and nights in winter. Rainfall index do not show any clear tendency on the annual scale. Nevertheless, the count of days when precipitation is greater than 20mm (R20

  17. Value of computed tomographic angiography in neck and extremity pediatric vascular trauma.

    Science.gov (United States)

    Hogan, Anthony R; Lineen, Edward B; Perez, Eduardo A; Neville, Holly L; Thompson, William R; Sola, Juan E

    2009-06-01

    We sought to define the sensitivity and specificity of computed tomographic angiography (CTA) in pediatric vascular injuries. All neck and extremity CTAs performed in pediatric patients at a level 1 trauma center were reviewed from 2001 to 2007. Overall, 78 patients were identified with an average age of 15.0 +/- 4.0 (0-18 years). Males outnumbered females 3.6:1. CTA was performed for 41 penetrating and 37 blunt traumas. Most penetrating injuries were due to missile wounds (71%) or stab wounds (17%). Eleven major vascular injuries resulted from penetrating trauma. For penetrating trauma, CTA was 100% sensitive and 93% specific. CTA for penetrating trauma had a positive predictive value (PPV) of 85% and negative predictive value (NPV) of 100%. Most blunt injuries were due to motor vehicle accidents (57%), followed by pedestrian hit by car (27%). Eight major vascular injuries resulted from blunt trauma. For blunt trauma, CTA was 88% sensitive and 100% specific. CTA for blunt trauma had a PPV of 100% and an NPV of 97%. The accuracy for penetrating and blunt trauma was 95% and 97%, respectively. CTA is highly sensitive, specific, and accurate for pediatric neck and extremity vascular trauma.

  18. THE RESULTS OF EXPERIMENTAL RESEARCH OF INFLUENCE OF ACOUSTIC AND MAGNETIC FIELD ON ELECTROCONDUCTIVITY AND PH VALUE OF HYDROPONIC SOLUTION

    Directory of Open Access Journals (Sweden)

    Korzhakov A. V.

    2015-06-01

    Full Text Available The article deals with the results of research of acoustic and magnetic field influence on conductivity and pH value of hydroponic solution. For carrying out researches in this area the hypothesis of possibility of nutrient solution influence on ions by means of an acoustic and magnetic field is set up. A laboratory scale plant was constructed for a pilot study of the hypothesis. The solution was moved in the tube passing through a ferrite ring with winding. Thus, the solution was exposed to the influence of acoustic and magnetic field. The object of research was hydroponic solution of (NH42SO4; (NH42HPO4; K2SO4; Ca(NO32; MgSO4 in water having adjusted concentration and acidity. The solution was taken from the tank of laboratory scale plant by means of the pump, passed through the working area of the acoustic and magnetic device, filter, and then was poured into the tank, from which the sample for pH level changing was taken. The pH value was measured at the temperature of 22С by using electronic pH-meter KL-009(1A. For control of instrument readings acidity was tested by universal test-paper. The initial pH value of solution made 5. As a result of acoustic and magnetic treatment of solution pH value of hydroponic solution increased from 6 to 6.9. The results show the possibility of pH value correction by small energy input

  19. Effects of pH values on the properties of buffalo and cow butter-based low-fat spreads

    Directory of Open Access Journals (Sweden)

    Abdeldaiem, A. M.

    2014-09-01

    Full Text Available The objective of this study was to characterize the effects of pH values (5, 5.5, 6, 6.5 and 7 on the properties of buffalo and cow butter-based low-fat spreads. Sensory evaluation of the samples decreased with an increase in pH values and during the storage periods. In addition, phase separation occurred with pH 6, 6.5 and 7. The differences in peroxide values and oil stability index among the samples compared to the control samples were slight, while peroxide values and oil stability index decreased during the storage periods. Changes in fatty acid composition among the pH treatments and during the storage periods were detected. Differences in solid fat contents among pH treatments separately and during the storage periods were negligible. A decline in the hardness and viscosity of the samples were accompanied by an increase in pH values, and the treatments had increased effects during the storage periods. Generally, an increase of pH values did not affect the melting profiles of the spreads. Additionally, changes between the melting profiles of buffalo and cow butter-based low-fat spreads were detected.El objetivo fue determinar los efectos del pH (5, 5.5, 6, 6.5 y 7 en las propiedades de mantequillas para untar bajas en grasa de búfalos y vacas. La puntuación sensorial de las muestras disminuyó con el aumento del pH y durante los períodos de almacenamiento, además, la separación de fases se produjo con pH de 6, 6,5 y 7. Se observaron diferencias en los valores de peróxido e índice de estabilidad de la grasa de las muestras en comparación con las muestras control, mientras que los valores de peróxido incrementaron, el índice de estabilidad de la grasa disminuyó durante los períodos de almacenamiento. Se observan cambios en la composición de ácidos grasos entre los tratamientos de pH y durante los períodos de almacenamiento. Las diferencias en el contenido de grasa sólida entre los tratamientos de pH por separado y durante los

  20. [Reduction of nitrobenzene by iron oxides bound Fe(II) system at different pH values].

    Science.gov (United States)

    Luan, Fu-Bo; Xie, Li; Li, Jun; Zhou, Qi

    2009-07-15

    Batch tests were conducted to investigate the reductive transformation of nitrobenzene by goethite, hematite, magnetite and steel converter slag bound Fe(II) system. And the reduction mechanism was explored at different pH values. Experimental results showed that hematite, magnetite and steel converter slag could adsorb Fe(II) on surfaces and form iron oxides bound Fe(II) system at pH from 6.5 to 7.0. The systems had strong reductive capacity and could reduce nitrobenzene to aniline. The reduction efficiency of nitrobenzene in surface bound Fe(II) system followed the sequence of magnetite, hematite and steel converter slag from high to low. The reduction efficiency of hematite and magnetite system increased with pH increasing. While it was almost pH independent in steel converter slag system. Although goethite adsorbed most of Fe(II) in solution, the adsorbed Fe(II) had no reductive activity for nitrobenzene. At pH 6.0, small amount of Fe(II) was adsorbed on magnetite and hematite and the systems did not show reductive activity for nitrobenzene. However, steel converter slag could adsorb Fe(II) at pH 6.0 and reduction efficiency almost equaled to the value at pH 7.0. When pH was above 7.5, dissolved Fe(II) could be converted to Fe(OH)2 and the newly formed Fe(OH)2 became the main redactor in the system. Under alkali condition, the presence of iron oxides inhibited the reduction capacity of system.

  1. Estimation of water activity from pH and °Brix values of some food products.

    Science.gov (United States)

    Gabriel, Alonzo A

    2008-06-01

    In this study, a predictive model for the estimation of water activity (aw(25°C)) as a function of pH (1.00-8.00) and °Brix (0-82.00) values of simulated food solutions (SFS) was developed, through response surface methodology. Response fit analyses resulted in a highly significant (pHBrix values within the defined variable ranges. The linear, quadratic and interactive influences of pH and °Brix on aw(25°C) were all significant (pH<0.0001). Model validations in SFS and in a number of actual food systems showed that the model had acceptable predictive performance, as indicated by the calculated accuracy and bias indices.

  2. Estimating return periods of extreme values from relatively short time series of winds

    Science.gov (United States)

    Jonasson, Kristjan; Agustsson, Halfdan; Rognvaldsson, Olafur; Arfeuille, Gilles

    2013-04-01

    An important factor for determining the prospect of individual wind farm sites is the frequency of extreme winds at hub height. Here, extreme winds are defined as the value of the highest 10 minutes averaged wind speed with a 50 year return period, i.e. annual exceeding probability of 2% (Rodrigo, 2010). A frequently applied method to estimate winds in the lowest few hundred meters above ground is to extrapolate observed 10-meter winds logarithmically to higher altitudes. Recent study by Drechsel et al. (2012) showed however that this methodology is not as accurate as interpolating simulated results from the global ECMWF numerical weather prediction (NWP) model to the desired height. Observations of persistent low level jets near Colima in SW-Mexico also show that the logarithmic approach can give highly inaccurate results for some regions (Arfeuille et al., 2012). To address these shortcomings of limited, and/or poorly representative, observations and extrapolations of winds one can use NWP models to dynamically scale down relatively coarse resolution atmospheric analysis. In the case of limited computing resources one has typically to make a compromise between spatial resolution and the duration of the simulated period, both of which can limit the quality of the wind farm siting. A common method to estimate maximum winds is to fit an extreme value distribution (e.g. Gumbel, gev or Pareto) to the maximum values of each year of available data, or the tail of these values. If data are only available for a short period, e.g. 10 or 15 years, then this will give a rather inaccurate estimate. It is possible to deal with this problem by utilizing monthly or weekly maxima, but this introduces new problems: seasonal variation, autocorrelation of neighboring values, and increased discrepancy between data and fitted distribution. We introduce a new method to estimate return periods of extreme values of winds at hub height from relatively short time series of winds, simulated

  3. Study on the pH Value Control Method%pH值控制方法的研究

    Institute of Scientific and Technical Information of China (English)

    郭红霞; 刘磊

    2012-01-01

    由于pH过程的非线性和滞后性,pH值的检测和控制在化工生产过程中并非易事,本文主要分析了pH值曲线的非线性特点,应用分段式变增益PID的处理方法,提出了pH过程的分段式变增益PID控制设计方法,设计了一种分段式变增益PID控制算法,利用MATLAB仿真技术对pH值控制系统进行了仿真研究并与常规的PID控制算法进行了仿真对比,有效的实现了对pH值的控制.%Due to nonlinear and hysteresis quality of pH process, detection and control of pH value is not easy in chemical production process. This paper mainly analyzed the nonlinear features of pH value curve, applied the processing method of segment type variable gain PID, made the segment type variable gain PID control design method of pH process, designed a segment type variable gain PID control algorithm, used MATLAB simulation technology to make simulation research on pH value control system and made simulation comparison to the general PID control algorithm. At last the control of the pH value is effectively implemented.

  4. Uranium fate in wetland mesocosms: Effects of plants at two iron loadings with different pH values

    Science.gov (United States)

    Small-scale continuous flow wetland mesocosms (~0.8 L) were used to evaluate how plant roots under different iron loadings affect uranium (U) mobility. When significant concentrations of ferrous iron (Fe) were present at circumneutral pH values, U concentrations in root exposed ...

  5. Estimating the Effect of Climate Change on Crop Yields and Farmland Values: The Importance of Extreme Temperatures

    Science.gov (United States)

    This is a presentation titled Estimating the Effect of Climate Change on Crop Yields and Farmland Values: The Importance of Extreme Temperatures that was given for the National Center for Environmental Economics

  6. Technical description of parameters influencing the pH value of suspension absorbent used in flue gas desulfurization systems.

    Science.gov (United States)

    Głomba, Michał

    2010-08-01

    As a result of the large limestone deposits available in Poland, the low cost of reagent acquisition for the largescale technological use and relatively well-documented processes of flue gas desulfurization (FGD) technologies based on limestone sorbent slurry, wet scrubbing desulfurization is a method of choice in Poland for flue gas treatment in energy production facilities, including power plants and industrial systems. The efficiency of FGD using the above method depends on several technological and kinetic parameters, particularly on the pH value of the sorbent (i.e., ground limestone suspended in water). Consequently, many studies in Poland and abroad address the impact of various parameters on the pH value of the sorbent suspension, such as the average diameter of sorbent particles (related to the limestone pulverization degree), sorbent quality (in terms of pure calcium carbonate [CaCO3] content of the sorbent material), stoichiometric surfeit of CaCO3 in relation to sulfur dioxide (SO2) absorbed from flue gas circulating in the absorption node, time of absorption slurry retention in the absorber tank, chlorine ion concentration in sorbent slurry, and concentration of dissolved metal salts (Na, K, Mg, Fe, Al, and others). This study discusses the results of laboratory-scale tests conducted to establish the effect of the above parameters on the pH value of limestone slurry circulating in the SO2 absorption node. On the basis of the test results, a correlation equation was postulated to help maintain the desirable pH value at the design phase of the wet FGD process. The postulated equation displays good coincidence between calculated pH values and those obtained using laboratory measurements.

  7. Water-, pH- and temperature relations of germination for the extreme xerophiles Xeromyces bisporus (FRR 0025), Aspergillus penicillioides (JH06THJ) and Eurotium halophilicum (FRR 2471).

    Science.gov (United States)

    Stevenson, Andrew; Hamill, Philip G; Dijksterhuis, Jan; Hallsworth, John E

    2017-03-01

    Water activity, temperature and pH are determinants for biotic activity of cellular systems, biosphere function and, indeed, for all life processes. This study was carried out at high concentrations of glycerol, which concurrently reduces water activity and acts as a stress protectant, to characterize the biophysical capabilities of the most extremely xerophilic organisms known. These were the fungal xerophiles: Xeromyces bisporus (FRR 0025), Aspergillus penicillioides (JH06THJ) and Eurotium halophilicum (FRR 2471). High-glycerol spores were produced and germination was determined using 38 media in the 0.995-0.637 water activity range, 33 media in the 2.80-9.80 pH range and 10 incubation temperatures, from 2 to 50°C. Water activity was modified by supplementing media with glycerol+sucrose, glycerol+NaCl and glycerol+NaCl+sucrose which are known to be biologically permissive for X. bisporus, A. penicillioides and E. halophilicum respectively. The windows and rates for spore germination were quantified for water activity, pH and temperature; symmetry/asymmetry of the germination profiles were then determined in relation to supra- and sub-optimal conditions; and pH- and temperature optima for extreme xerophilicity were quantified. The windows for spore germination were ~1 to 0.637 water activity, pH 2.80-9.80 and > 10 and < 44°C, depending on strain. Germination profiles in relation to water activity and temperature were asymmetrical because conditions known to entropically disorder cellular macromolecules, i.e. supra-optimal water activity and high temperatures, were severely inhibitory. Implications of these processes were considered in relation to the in-situ ecology of extreme conditions and environments; the study also raises a number of unanswered questions which suggest the need for new lines of experimentation. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  8. A goodness-of-fit test for bivariate extreme-value copulas

    CERN Document Server

    Genest, Christian; Nešlehová, Johanna; Yan, Jun; 10.3150/10-BEJ279

    2011-01-01

    It is often reasonable to assume that the dependence structure of a bivariate continuous distribution belongs to the class of extreme-value copulas. The latter are characterized by their Pickands dependence function. In this paper, a procedure is proposed for testing whether this function belongs to a given parametric family. The test is based on a Cram\\'{e}r--von Mises statistic measuring the distance between an estimate of the parametric Pickands dependence function and either one of two nonparametric estimators thereof studied by Genest and Segers [Ann. Statist. 37 (2009) 2990--3022]. As the limiting distribution of the test statistic depends on unknown parameters, it must be estimated via a parametric bootstrap procedure, the validity of which is established. Monte Carlo simulations are used to assess the power of the test and an extension to dependence structures that are left-tail decreasing in both variables is considered.

  9. Thymic Selection of T-Cell Receptors as an Extreme Value Problem

    Science.gov (United States)

    Kosmrlj, Andrej; Chakraborty, Arup K.; Kardar, Mehran; Shakhnovich, Eugene I.

    2010-03-01

    T lymphocytes (T cells) orchestrate adaptive immune responses that clear pathogens from infected hosts. T cells recognize short peptides (p) derived from foreign proteins, which are bound to major histocompatibility complex (MHC) gene products (displayed on antigen- presenting cells). Recognition occurs when T cell receptor (TCR) proteins expressed on T cells bind sufficiently strongly to antigen- derived pMHC complexes on the surface of antigen-presenting cells. A diverse repertoire of self-tolerant TCR sequences is shaped during development of T cells in the thymus by processes called positive and negative selection. We map thymic selection processes to an extreme value problem and provide analytic expression for the amino acid composition of selected TCR sequences (which enable its recognition functions).

  10. Quantitative Study on Nonmetallic Inclusion Particles in Steels by Automatic Image Analysis With Extreme Values Method

    Institute of Scientific and Technical Information of China (English)

    Cássio Barbosa; José Brant de Campos; J(ǒ)neo Lopes do Nascimento; Iêda Maria Vieira Caminha

    2009-01-01

    The presence of nonmetallic inclusion particles which appear during steelmaking process is harmful to the properties of steels, which is mainly as a function of some aspects such as size, volume fraction, shape, and distribution of these particles. The automatic image analysis technique is one of the most important tools for the quantitative determination of these parameters. The classical Student approach and the Extreme Values Method (EVM) were used for the inclusion size and shape determination and the evaluation of distance between the inclusion particles. The results thus obtained indicated that there were significant differences in the characteristics of the inclusion particles in the analyzed products. Both methods achieved results with some differences, indicating that EVM could be used as a faster and more reliable statistical methodology.

  11. Network Traffic Based on GARCH-M Model and Extreme Value Theory

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    GARCH-M (generalized autoregressive conditional heteroskedasticity in the mean) model is used to analyse the volatility clustering phenomenon in mobile communication network traffic.Normal distribution, t distribution and generalized Pareto distribution assumptions are adopted respectively to simulate the random component in the model. The demonstration of the quantile of network traffic series indicates that common GARCH-M model can partially deal with the "fat tail"problem. However, the "fat tail" characteristic of the random component directly affects the accuracy of the calculation. Even t distribution is based on the assumption for all the data. On the other hand, extreme value theory, which only concentrates on the tail distribution, can provide more accurate result for high quantiles. The best result is obtained based on the generalized Pareto distribution assumption for the random component in the GARCH-M model.

  12. Prognostic value of biochemical variables for survival after surgery for metastatic bone disease of the extremities.

    Science.gov (United States)

    Sørensen, Michala Skovlund; Hovgaard, Thea Bechman; Hindsø, Klaus; Petersen, Michael Mørk

    2017-03-01

    Prediction of survival in patients having surgery for metastatic bone disease in the extremities (MBDex) has been of interest in more than two decades. Hitherto no consensus on the value of biochemical variables has been achieved. Our purpose was (1) to investigate if standard biochemical variables have independent prognostic value for survival after surgery for MBDex and (2) to identify optimal prognostic cut off values for survival of biochemical variables. In a consecutive cohort of 270 patients having surgery for MBDex, we measured preoperative biochemical variables: hemoglobin, alkaline phosphatase, C-reactive protein and absolute, neutrophil and lymphocyte count. ROC curve analyses were performed to identify optimal cut off levels. Independent prognostic factors for variables were addressed with multiple Cox regression analyses. Optimal cut off levels were identified as: hemoglobin 7.45 mmol/L, absolute lymphocyte count 8.5 × 10(9) /L, neutrophil 5.68 × 10(9) /L, lymphocyte 1.37 × 10(9) /L, C-reactive protein 22.5 mg/L, and alkaline phosphatase 129 U/L. Regression analyses found alkaline phosphatase (HR 2.49) and neutrophil count (HR 2.49) to be independent prognostic factors. We found neutrophil count and alkaline phosphatase to be independent prognostic variables in predicting survival in patients after surgery for MBDex. © 2016 Wiley Periodicals, Inc.

  13. Inhibition Effect of Glycerol on the Corrosion of Copper in NaCl Solutions at Different pH Values

    Directory of Open Access Journals (Sweden)

    Santos Lorenzo Chi-Ucán

    2014-01-01

    Full Text Available The inhibitory effect of glycerol on copper corrosion in aerated NaCl (0.5 M solutions at three pH values (4, 7, and 10 was evaluated. Inhibition efficiency was assessed with conventional electrochemical techniques: open circuit potential, potentiodynamic polarization, and electrochemical impedance analysis. Glycerol reduced the corrosion rate of copper in NaCl solutions. The best inhibition effect (η≈83% was produced in alkaline (pH 10 chloride media. This effect can be ascribed to increased viscosity and the presence of copper-glycerol complexes.

  14. Uncertainties of the 50-year wind from short time series using generalized extreme value distribution and generalized Pareto distribution

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Mann, Jakob; Rathmann, Ole

    2015-01-01

    as a guideline for applying GEVD and GPD to wind time series of limited length. The data analysis shows that, with reasonable choice of relevant parameters, GEVD and GPD give consistent estimates of the return winds. For GEVD, the base period should be chosen in accordance with the occurrence of the extreme wind......This study examines the various sources to the uncertainties in the application of two widely used extreme value distribution functions, the generalized extreme value distribution (GEVD) and the generalized Pareto distribution (GPD). The study is done through the analysis of measurements from...

  15. Actin proteolysis during ripening of dry fermented sausages at different pH values.

    Science.gov (United States)

    Berardo, A; Devreese, B; De Maere, H; Stavropoulou, D A; Van Royen, G; Leroy, F; De Smet, S

    2017-04-15

    In dry fermented sausages, myofibrillar proteins undergo intense proteolysis generating small peptides and free amino acids that play a role in flavour generation. This study aimed to identify small peptides arising from actin proteolysis, as influenced by the type of processing. Two acidification profiles were imposed, in order to mimic the pH normally obtained in southern-type and northern-type dry fermented sausages. The identification of peptides was done by liquid chromatography coupled to mass spectrometry in a data-independent positive mode of acquisition (LC-MS(E)). During manufacturing of the dry fermented sausages, actin was highly proteolysed, especially in nine regions of the sequence. After fermentation, 52 and 42 actin-derived peptides were identified at high and low pH, respectively, which further increased to 66 and 144 peptides, respectively, at the end of ripening. Most peptides were released at the cleavage sites of cathepsins B and D, which thus play an important role.

  16. Generalised extreme value distributions provide a natural hypothesis for the shape of seed mass distributions.

    Directory of Open Access Journals (Sweden)

    Will Edwards

    Full Text Available Among co-occurring species, values for functionally important plant traits span orders of magnitude, are uni-modal, and generally positively skewed. Such data are usually log-transformed "for normality" but no convincing mechanistic explanation for a log-normal expectation exists. Here we propose a hypothesis for the distribution of seed masses based on generalised extreme value distributions (GEVs, a class of probability distributions used in climatology to characterise the impact of event magnitudes and frequencies; events that impose strong directional selection on biological traits. In tests involving datasets from 34 locations across the globe, GEVs described log10 seed mass distributions as well or better than conventional normalising statistics in 79% of cases, and revealed a systematic tendency for an overabundance of small seed sizes associated with low latitudes. GEVs characterise disturbance events experienced in a location to which individual species' life histories could respond, providing a natural, biological explanation for trait expression that is lacking from all previous hypotheses attempting to describe trait distributions in multispecies assemblages. We suggest that GEVs could provide a mechanistic explanation for plant trait distributions and potentially link biology and climatology under a single paradigm.

  17. Risk-Cost Estimation of On-Site Wastewater Treatment System Failures Using Extreme Value Analysis.

    Science.gov (United States)

    Kohler, Laura E; Silverstein, JoAnn; Rajagopalan, Balaji

    2017-05-01

      Owner resistance to increasing regulation of on-site wastewater treatment systems (OWTS), including obligatory inspections and upgrades, moratoriums and cease-and-desist orders in communities around the U.S. demonstrate the challenges associated with managing risks of inadequate performance of owner-operated wastewater treatment systems. As a result, determining appropriate and enforceable performance measures in an industry with little history of these requirements is challenging. To better support such measures, we develop a statistical method to predict lifetime failure risks, expressed as costs, in order to identify operational factors associated with costly repairs and replacement. A binomial logistic regression is used to fit data from public records of reported OWTS failures, in Boulder County, Colorado, which has 14 300 OWTS to determine the probability that an OWTS will be in a low- or high-risk category for lifetime repair and replacement costs. High-performing or low risk OWTS with repairs and replacements below the threshold of $9000 over a 40-year life are associated with more frequent inspections and upgrades following home additions. OWTS with a high risk of exceeding the repair cost threshold of $18 000 are further analyzed in a variation of extreme value analysis (EVA), Points Over Threshold (POT) where the distribution of risk-cost exceedance values are represented by a generalized Pareto distribution. The resulting threshold cost exceedance estimates for OWTS in the high-risk category over a 40-year expected life ranged from $18 000 to $44 000.

  18. Actual and future trends of extreme values of temperature for the NW Iberian Peninsula

    Science.gov (United States)

    Taboada, J.; Brands, S.; Lorenzo, N.

    2009-09-01

    It is now very well established that yearly averaged temperatures are increasing due to anthropogenic climate change. In the area of Galicia (NW Spain) this trend has also been determined. The main objective of this work is to assess actual and future trends of different extreme indices of temperature, which are of curcial importance for many impact studies. Station data for the study was provided by the CLIMA database of the regional government of Galicia (NW Spain). As direct GCM-output significantly underestimates the variance of daily surface temperature variables in NW Spain, these variables are obtained by applying a statistical downscaling technique (analog method), using 850hPa temperature and mean sea level pressure as combined predictors. The predictor fields have been extracted from three GCMs participating in the IPCC AR4 under A1, A1B and A2 scenarios. The definitions of the extreme indices have been taken from the joint CCl/CLIVAR/JCOMM Expert Team (ET) on Climate Change Detection and Indices (ETCCDI) This group has defined a set of standard extreme values to simplify intercomparisons of data from different regions of the world. For the temperatures in the period 1960-2006, results show a significant increase of the number of days with maximum temperatures above the 90th percentile. Furthermore, a significant decrease of the days with maximum temperatures below the 10th percentile has been found. The tendencies of minimum temperatures are reverse: less nights with minimum temperatures below 10th percentile, and more with minimum temperatures above 90th percentile. Those tendencies can be observed all over the year, but are more pronounced in summer. We have also calculated the relationship between the above mentioned extreme values and different teleconnection patterns appearing in the North Atlantic area. Results show that local tendencies are associated with trends of EA (Eastern Atlantic) and SCA (Scandinavian) patterns. NAO (North Atlantic

  19. Influence of the pH value of anthocyanins on the electrical properties of dye-sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Irén Juhász Junger

    2017-03-01

    Full Text Available In recent years the harvesting of renewable energies became of great importance. This led to a rapid development of dye-sensitized solar cells which can be produced from low-purity materials. The best electrical properties are provided by cells prepared using synthetical, ruthenium based dyes. Unfortunately, most of them are toxic and expensive. The anthocyanins extracted for example from hibiscus flowers yield a more cost-effective and eco-friendly alternative to toxic dyes, however, with a loss of solar cell efficiency. In this article the possibility of improvement of the conversion efficiency by modification of the pH value of the dye is investigated. By decrease of the pH value, an increase of efficiency by a factor of two was achieved.

  20. Generalized Extreme Value Distribution Models for the Assessment of Seasonal Wind Energy Potential of Debuncha, Cameroon

    Directory of Open Access Journals (Sweden)

    Nkongho Ayuketang Arreyndip

    2016-01-01

    Full Text Available The method of generalized extreme value family of distributions (Weibull, Gumbel, and Frechet is employed for the first time to assess the wind energy potential of Debuncha, South-West Cameroon, and to study the variation of energy over the seasons on this site. The 29-year (1983–2013 average daily wind speed data over Debuncha due to missing values in the years 1992 and 1994 is gotten from NASA satellite data through the RETScreen software tool provided by CANMET Canada. The data is partitioned into min-monthly, mean-monthly, and max-monthly data and fitted using maximum likelihood method to the two-parameter Weibull, Gumbel, and Frechet distributions for the purpose of determining the best fit to be used for assessing the wind energy potential on this site. The respective shape and scale parameters are estimated. By making use of the P values of the Kolmogorov-Smirnov statistic (K-S and the standard error (s.e analysis, the results show that the Frechet distribution best fits the min-monthly, mean-monthly, and max-monthly data compared to the Weibull and Gumbel distributions. Wind speed distributions and wind power densities of both the wet and dry seasons are compared. The results show that the wind power density of the wet season was higher than in the dry season. The wind speeds at this site seem quite low; maximum wind speeds are listed as between 3.1 and 4.2 m/s, which is below the cut-in wind speed of many modern turbines (6–10 m/s. However, we recommend the installation of low cut-in wind turbines like the Savonius or Aircon (10 KW for stand-alone low energy need.

  1. Influence of lactic acid bacteria, probiotic cultures and pH value in fermented yoghurt drink to sensory quality

    Directory of Open Access Journals (Sweden)

    Hana Šulcerová

    2009-01-01

    Full Text Available Nowadays, we can see on market mainly fermented milk products with addition of probiotic microorganisms, especially strains of Lactobacillus and Bifidobacterium. We can meet also other types of pro­bio­tic products. It is recommended to consume at least 100 grams of fermented milk products with mi­ni­mal concentration of 106 of probiotics in one gram or mililitr of product daily for reaching positive effect on men’s health. During fermentation of the carbohydrates, proteins and lipids are disunite and many of aromatic compounds ane compose. They give a typical sensory characteristic to fermented milk products. For quality and quantity level of probiotics, changes of pH value and sensory qua­li­ty of five kinds of fermented milk product Yoghurt Drink with different flavour were analyzed during the whole expiration period (28 days. Obtained results were statistically evaluated via the analysis of variance and the method of multiple comparison according to Tukey test (P < 0,010 and (P < 0,001. During the minimal endurance time lactic acid bacteria and Bifidobacterium sp. were evaluated and changes of descriptors and pH value were detected. Number of LAB was up to 107 CFU/ml in all samples during 28 days of analysis. Only at sample 2 the number of LAB was 106 CFU/ml. Bifidobacterium sp. grew about degree. The number of LAB and Bifidobacterium sp. of yoghurt drink correspond with public notice number 77/2003 Sb, LAB 107 nad Bifidobacterium sp. 106 KTJ / ml. During 28 days of storage the pH value decreased. The biggest pH drop was recorded between 21. and 28. days of sto­ra­ge in all samples. The beginning pH value was 4.03–4.07 and the final value was between 3.80–3.95.The results of sensory evaluation processed by analysis of dispersion according to type were statistically conlusive in descriptors thickness, texture, intensity of smell, pleasantness of taste and general impression. The results of sensory evaluation processed by

  2. Entanglement between two subsystems, the Wigner semicircle and extreme value statistics

    CERN Document Server

    Bhosale, Udaysinh T; Lakshminarayan, Arul

    2012-01-01

    The entanglement between two arbitrary subsystems of random pure states is studied via properties of the density matrix's partial transpose, $\\rho_{12}^{T_2}$. The density of states of $\\rho_{12}^{T_2}$ is close to the semicircle law when both subsystems have dimensions which are not too small and are of the same order. A simple random matrix model for the partial transpose is found to capture the entanglement properties well, including a transition across a critical dimension. Log-negativity is used to quantify entanglement between subsystems and approximate analytic formulas for this are derived. The skewness of the eigenvalue density of $\\rho_{12}^{T_2}$ is derived analytically, using the average of the third moment that is also shown to be related to a generalization of the Kempe invariant. Extreme value statistics, especially the Tracy-Widom distribution, is found to be useful in calculating the fraction of entangled states at critical dimensions. These results are tested in a quantum dynamical system of...

  3. Brownian limits, local limits, extreme value and variance asymptotics for convex hulls in the ball

    CERN Document Server

    Calka, Pierre; Yukich, J E

    2009-01-01

    The paper of Schreiber and Yukich [40] establishes an asymptotic representation for random convex polytope geometry in the unit ball $\\B_d, d \\geq 2,$ in terms of the general theory of stabilizing functionals of Poisson point processes as well as in terms of the so-called generalized paraboloid growth process. This paper further exploits this connection, introducing also a dual object termed the paraboloid hull process. Via these growth processes we establish local functional and measure-level limit theorems for the properly scaled radius-vector and support functions as well as for curvature measures and $k$-face empirical measures of convex polytopes generated by high density Poisson samples. We use general techniques of stabilization theory to establish Brownian sheet limits for the defect volume and mean width functionals, and we provide explicit variance asymptotics and central limit theorems for the $k$-face and intrinsic volume functionals. We establish extreme value theorems for radius-vector and suppo...

  4. Application of the extreme value approaches to the apparent magnitude distribution of the earthquakes

    Science.gov (United States)

    Tinti, S.; Mulargia, F.

    1985-03-01

    The apparent magnitude of an earthquake y is defined as the observed magnitude value and differs from the true magnitude m because of the experimental noise n. If f(m) is the density distribution of the magnitude m, and if g(n) is the density distribution of the error n, then the density distribution of y is simply computed by convolving f and g, i.e. h(y)=f*g. If the distinction between y and m is not realized, any statistical analysis based on the frequency-magnitude relation of the earthquake is bound to produce questionable results. In this paper we investigate the impact of the apparent magnitude idea on the statistical methods that study the earthquake distribution by taking into account only the largest (or extremal) earthquakes. We use two approaches: the Gumbel method based on Gumbel theory ( Gumbel, 1958), and the Poisson method introduced by Epstein and Lomnitz (1966). Both methods are concerned with the asymptotic properties of the magnitude distributions. Therefore, we study and compare the asymptotic behaviour of the distributions h(y) and f(m) under suitable hypotheses on the nature of the experimental noise. We investigate in detail two dinstinct cases: first, the two-side limited symmetrical noise, i.e. the noise that is bound to assume values inside a limited region, and second, the normal noise, i.e. the noise that is distributed according to a normal symmetric distribution. We further show that disregarding the noise generally leads to biased results and that, in the framework of the apparent magnitude, the Poisson approach preserves its usefulness, while the Gumbel method gives rise to a curious paradox.

  5. Effect of pH values of two bleaching gels on enamel microhardness.

    Science.gov (United States)

    Araujo, Natalia Costa; da Costa Soares, Manuella Uilmann Silva; Nery, Marcela Maria; Sales, Wagno Silva; Gerbi, Marleny Elizabeth Martinez

    2013-07-01

    This study evaluated the influence of bleaching gel pH and the effect of remineralizing gels after bleaching in different time intervals. Sixty bovine incisors were divided into 2 groups (n = 30). Group 1 was bleached with a 35% hydrogen peroxide (HP) acid gel and Group 2 was bleached with a 35% HP neutral gel. Each group was then divided into 3 subgroups (n = 10) according to the post-bleaching treatment used: storage in artificial saliva, application of a fluoride gel, or application of a gel consisting of fluoride, potassium nitrate, and nanostructured calcium phosphate. Specimens were stored in artificial saliva, and enamel microhardness was evaluated at 24 hours and 15 days postbleaching. Vickers microhardness data were analyzed by means of 2-way ANOVA, with repeated measurements and Bonferroni's post-hoc test. Twenty-four hours after bleaching, no significant differences were found between the bleaching gels. At 15 days postbleaching, Group 2 samples demonstrated a significant reduction in microhardness. No significant differences were found between the remineralizing gels, though all of the postbleaching treatments after the use of 35% neutral gel were able to re-establish baseline microhardness. It was concluded that neutral bleaching gel significantly reduced enamel microhardness 15 days after bleaching and that the use of remineralizing gels did not significantly enhance the microhardness of bleached enamel. However, in clinical situations, the acquired enamel pellicle protects tooth surfaces, and postbleaching, decalcified enamel would undergo recalcification. This study indicates that it is important to consider the bleaching agent's pH and composition when treating patients with reduced salivary secretion.

  6. Volcanic hazard assessment for the Canary Islands (Spain) using extreme value theory

    Science.gov (United States)

    Sobradelo, R.; Martí, J.; Mendoza-Rosas, A. T.; Gómez, G.

    2011-10-01

    The Canary Islands are an active volcanic region densely populated and visited by several millions of tourists every year. Nearly twenty eruptions have been reported through written chronicles in the last 600 yr, suggesting that the probability of a new eruption in the near future is far from zero. This shows the importance of assessing and monitoring the volcanic hazard of the region in order to reduce and manage its potential volcanic risk, and ultimately contribute to the design of appropriate preparedness plans. Hence, the probabilistic analysis of the volcanic eruption time series for the Canary Islands is an essential step for the assessment of volcanic hazard and risk in the area. Such a series describes complex processes involving different types of eruptions over different time scales. Here we propose a statistical method for calculating the probabilities of future eruptions which is most appropriate given the nature of the documented historical eruptive data. We first characterize the eruptions by their magnitudes, and then carry out a preliminary analysis of the data to establish the requirements for the statistical method. Past studies in eruptive time series used conventional statistics and treated the series as an homogeneous process. In this paper, we will use a method that accounts for the time-dependence of the series and includes rare or extreme events, in the form of few data of large eruptions, since these data require special methods of analysis. Hence, we will use a statistical method from extreme value theory. In particular, we will apply a non-homogeneous Poisson process to the historical eruptive data of the Canary Islands to estimate the probability of having at least one volcanic event of a magnitude greater than one in the upcoming years. This is done in three steps: First, we analyze the historical eruptive series to assess independence and homogeneity of the process. Second, we perform a Weibull analysis of the distribution of repose

  7. Volcanic hazard assessment for the Canary Islands (Spain using extreme value theory

    Directory of Open Access Journals (Sweden)

    R. Sobradelo

    2011-10-01

    Full Text Available The Canary Islands are an active volcanic region densely populated and visited by several millions of tourists every year. Nearly twenty eruptions have been reported through written chronicles in the last 600 yr, suggesting that the probability of a new eruption in the near future is far from zero. This shows the importance of assessing and monitoring the volcanic hazard of the region in order to reduce and manage its potential volcanic risk, and ultimately contribute to the design of appropriate preparedness plans. Hence, the probabilistic analysis of the volcanic eruption time series for the Canary Islands is an essential step for the assessment of volcanic hazard and risk in the area. Such a series describes complex processes involving different types of eruptions over different time scales. Here we propose a statistical method for calculating the probabilities of future eruptions which is most appropriate given the nature of the documented historical eruptive data. We first characterize the eruptions by their magnitudes, and then carry out a preliminary analysis of the data to establish the requirements for the statistical method. Past studies in eruptive time series used conventional statistics and treated the series as an homogeneous process. In this paper, we will use a method that accounts for the time-dependence of the series and includes rare or extreme events, in the form of few data of large eruptions, since these data require special methods of analysis. Hence, we will use a statistical method from extreme value theory. In particular, we will apply a non-homogeneous Poisson process to the historical eruptive data of the Canary Islands to estimate the probability of having at least one volcanic event of a magnitude greater than one in the upcoming years. This is done in three steps: First, we analyze the historical eruptive series to assess independence and homogeneity of the process. Second, we perform a Weibull analysis of the

  8. Environmental Scanning Electron Microscopy characterization of the adhesion of conidia from Penicillium expansum to cedar wood substrata at different pH values.

    Science.gov (United States)

    El Abed, Soumya; Ibnsouda, Saad Koraichi; Latrache, Hassan; Meftah, Hasna; Tahri, Nezha Joutey; Hamadi, Fatima

    2012-04-01

    Initial microbial adhesion to surfaces is a complicated process that is affected by a number of factors. An important property of a solution that may influence adhesion is pH. The surface properties of the cedar wood were characterized by the sessile drop technique. Moreover, the interfacial free energy of surface adhesion to the cedar wood was determined under pH values (2, 3, 5, 7, 9 and 11). The results showed that cedar wood examined at different pH levels could be considered hydrophobic ranged from Giwi = -13.1 mJ/m(2) to Giwi = -75 mJ/m(2). We noted that the electron-donor character of cedar wood was important at both basic and limit acidic conditions (pH 11 and pH 3) and it decreased at intermediate pH (pH 5). The cedar wood substratum presents a weak electron acceptor under various pH's. In addition, the adhesion of conidia from Penicilllium expansum to the cedar wood surfaces at different pH values (2, 3, 5, 7, 9 and 11) was investigated using Environmental Scanning Electron Microscopy and image analysis was assessed with the Mathlab(®) program. The data analysis showed that the conidia from P. expansum were strongly influenced by the pH. The maximum adhesion occurs in the pH 11 and pH 3 and decreased to 24% at pH 5.

  9. Evaluation of Thiol Raman Activities and pKa Values Using Internally Referenced Raman-Based pH Titration.

    Science.gov (United States)

    Suwandaratne, Nuwanthi; Hu, Juan; Siriwardana, Kumudu; Gadogbe, Manuel; Zhang, Dongmao

    2016-04-05

    Thiols, including organothiol and thiol-containing biomolecules, are among the most important classes of chemicals that are used broadly in organic synthesis, biological chemistry, and nanosciences. Thiol pKa values are key indicators of thiol reactivity and functionality. Reported herein is an internally referenced Raman-based pH titration method that enables reliable quantification of thiol pKa values for both mono- and dithiols in water. The degree of thiol ionization is monitored directly using the peak intensity of the S-H stretching feature in the 2600 cm(-1) region relative to an internal reference peak as a function of the titration solution's pH. The thiol pKa values and Raman activity relative to its internal reference were then determined by curve fitting the experimental data with equations derived on the basis of the Henderson-Hasselbalch equation. Using this Raman titration method, we determined for the first time the first and second thiol pKa values for 1,2-benzenedithiol in water. This Raman-based method is convenient to implement, and its underlying theory is easy to follow. It should therefore have broad application for thiol pKa determinations and verification.

  10. Microencapsulation of butyl stearate with melamine-formaldehyde resin: Effect of decreasing the pH value on the composition and thermal stability of microcapsules

    Directory of Open Access Journals (Sweden)

    M. Krajnc

    2012-10-01

    Full Text Available The object of this study was to investigate how different decreasing of pH regimes during microencapsulation process with melamine-formaldehyde (MF resin affects the composition, morphology and thermal stability of microcapsules containing a phase-change material (PCM. Technical butyl stearate was used as PCM. Microencapsulation was carried out at 70°C. For all experiments the starting pH value was 6.0. After one hour of microencapsulation at the starting pH value, the pH value was lowered to final pH value (5.5; 5.0; 4.5 in a stepwise or linear way. The properties of microcapsules were monitored during and after the microencapsulation process. The results showed that pH value decreasing regime was critical for the morphology and stability of microcapsules. During microencapsulations with a stepwise decrease of pH value we observed faster increase of the amount of MF resin in the microencapsulation product compared to the microencapsulations with a linear pH value decrease. However, faster deposition in the case of microencapsulations with stepwise decrease of pH value did not result in thicker MF shells. The shell thickness increased much faster when the pH value was decreased in a linear way or in several smaller steps. It was shown that for the best thermal stability of microcapsules, the pH value during microencapsulation had to be lowered in a linear way or in smaller steps to 5.0 or lower.

  11. Characteristics of episodes with extremely low ozone values in the northern middle latitudes 1957−2000

    Directory of Open Access Journals (Sweden)

    D. S. Balis

    Full Text Available A number of episodes are observed when the total ozone for 2 to 3 days has fallen below 220 matm-cm in the northern mid- and polar latitudes in autumn. The occurrences of such episodes represent ozone deviations of about one-third from the pre-1976 Oct-Nov-Dec monthly mean! By using primarily quality checked Dobson data, a clear identification was made of more than three dozen short spells with extremely low ozone in the 1957–1978 period. In the following twenty-two years (1979–2000, using mainly TOMS data, one can identify ~ 46 cases with ozone values falling below 220 matm-cm for longer than 1 day, with each time over an area greater than 500,000 km2 . The Ozone Mass Deficiency (O3MD from the pre-1976 average ozone values over the affected area was ~2.8 Mt per day, i.e. four to seven times greater than it would be, assuming only a long-term trend in the Oct-Nov-Dec period. The Extremely Low Ozone (ELO3 events on the day of their appearance over the N. Atlantic/European region contribute to the O3MD by representing 16% of the deficiency due to the Oct-Nov trend in the entire 40–65° N latitudinal belt. The O3MD of the greater pool with low ozone (here taken as <260 matm-cm surrounding the area of the lowest events could contribute on the day of their appearance in Oct-Nov up to 60% and in December, ~30% to the deficiency due to the trend over the entire 40–65° N belt. Analysis of synoptic charts, supported by a backward trajectory on the isentropic surfaces 350 and 380 K, shows that in most of the events, subtropical air masses with low ozone content were transported from the Atlantic toward the UK, Scandinavia, and in many cases, further to the western sub-polar regions of Russia. This transport was sometimes combined with upward motions above a tropospheric anticyclone which lifted low ozone mixing ratios to higher altitudes. The ELO3 events cause a significant deficiency above the tropopause where, in general, the subtropical air is

  12. A principle to correlate extreme values of excess thermody-namic functions with partial molar quantities

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Excess thermodynamic properties are widely used quantitatively for fluids. It was found that at constant temperature and pressure a molar excess quantity of a mutually miscible binary mixture at the extreme points equals the excess partial molar quantities of the two components, i.e. , forming a triple cross point. The relationship is hold for properties such as enthalpy, entropy, Gibbs free energy, and volume, and is applicable for excess functions with multi extreme points. Solutions at extreme points can be referred to as special mixtures. Particularly for a special mixture of Gibbs free energy, activity coefficients of the two components are identical.

  13. A principle to correlate extreme values of excess thermodynamic functions with partial molar quantities

    Institute of Scientific and Technical Information of China (English)

    尉志武; 刘芸; 周蕊; 薛芳渝

    2001-01-01

    Excess thermodynamic properties are widely used quantitatively for fluids. It was found that at constant temperature and pressure a molar excess quantity of a mutually miscible binary mixture at the extreme points equals the excess partial molar quantities of the two components, i.e.F1E = F2E = FmE , forming a triple cross point. The relationship is hold for properties such as en-thalpy, entropy, Gibbs free energy, and volume, and is applicable for excess functions with multi extreme points. Solutions at extreme points can be referred to as special mixtures. Particularly fora special mixture of Gibbs free energy, activity coefficients of the two components are identical.

  14. Capacitance Characterization of the Effect of pH Value on the Self-assembled Monolayers of Octadecanethiol

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, the membrane capacitance (Cm), which was obtained from the electro- chemical impedance spectroscopy (EIS) method, was used to characterize the effect of pH value on the self-assembled monolayers (SAMs) of octadecanethiol(18SH) for the first time. The results not only strongly proved that inorganic ions could penetrate the SAMs of 18SH, but also ascertained that SAMs of 18SH were not an absolute of free of ion-penetration. Verifying the existence of pin-holes in the octadecanethiol SAMs was the main contribution of this paper, which coincided with the former conjecture very well.

  15. A smart DNA tetrahedron that isothermally assembles or dissociates in response to the solution pH value changes.

    Science.gov (United States)

    Liu, Zhiyu; Li, Yingmei; Tian, Cheng; Mao, Chengde

    2013-06-10

    This communication reports a DNA tetrahedron whose self-assembly is triggered by an acidic environment. The key element is the formation/dissociation of a short, cytosine (C)-containing, DNA triplex. As the solution pH value oscillates between 5.0 and 8.0, the DNA triplex will form and dissociate that, in turn, leads to assembly or disassembly of the DNA tetrahedron, which has been demonstrated by native polyacrylamide gel electrophoresis (PAGE). We believe that such environment-responsive behavior will be important for potential applications of DNA nanocages such as on-demand drug release.

  16. Femtosecond transient absorption spectroscopy study of the early events of norfloxacin in aqueous solutions with varying pH values.

    Science.gov (United States)

    Su, Tao; Li, Ming-De; Ma, Jiani; Wong, Naikei; Phillips, David Lee

    2014-11-26

    The photophysics and photochemistry of norfloxacin (NF) have been investigated in aqueous solutions of different pH using femtosecond transient absorption spectroscopy (fs-TA). Resonance Raman spectroscopic experiments on NF have also been conducted in aqueous solutions of different pH to characterize the vibrational and structural information on the initial forms of NF. The experimental results in combination with density functional theory calculations of the key intermediates help us to elucidate the early events for NF after photoexcitation in aqueous solutions with varying pH values. The fs-TA results indicate that NF mainly underwent photophysical processes on the early delay time scale (before 3 ns), and no photochemical reactions occurred on this time scale. Specifically, after the irradiation of NF, the molecule reaches a higher excited singlet Sn and then decays to the lowest-lying excited singlet state S1 followed by intersystem crossing to transform into the lowest-lying triplet state T1 with a high efficiency, with an exception that there is a lower efficiency observed in basic aqueous solution due to the generation of an intramolecular electron transfer as an additional pathway to waste energy.

  17. Choosing the Mean versus an Extreme Resolution for Intrapersonal Values Conflicts: Is the Mean Usually More Golden?

    Science.gov (United States)

    Kinnier, Richard T.

    1984-01-01

    Examined the resolution of value conflicts in 60 adults who wrote a solution to their conflicts. Compared extreme resolutions with those representing compromise. Compromisers and extremists did not differ in how rationally resolved they were about their solutions but compromisers felt better about their solutions. (JAC)

  18. Extreme Value Predictions for Wave- and Wind-induced Loads on Floating Offshore Wind Turbines using FORM

    DEFF Research Database (Denmark)

    Joensen, Sunvard; Jensen, Jørgen Juncher; Mansour, Alaa E.

    2007-01-01

    The aim of the present paper is to advocate for a very effective stochastic procedure, based on the First Order Reliability Method (FORM), for extreme value predic-tions related to wave induced loads. Due to the efficient optimisation procedures implemented in standard FORM codes and the short du...

  19. A lesson from science in polar extreme environments: ethics and social values for primary school

    Science.gov (United States)

    La Longa, Federica; Crescimbene, Massimo; Alfonsi, Lucilla; Romano, Vincenzo; Cesaroni, Claudio

    2015-04-01

    experiences (doing); to develop civics path linked to "sense of belonging and citizenship", that will make the children aware that Antarctica does not belong to anyone but it belongs to everybody: it is a common and unique good (being). The proposed work is an example of how it is possible, by means of educational paths, promote and support integration values between human beings and nature also in extreme environments as the Antarctic continent.

  20. Extreme value statistics for two-dimensional convective penetration in a pre-main sequence star

    Science.gov (United States)

    Pratt, J.; Baraffe, I.; Goffrey, T.; Constantino, T.; Viallet, M.; Popov, M. V.; Walder, R.; Folini, D.

    2017-08-01

    Context. In the interior of stars, a convectively unstable zone typically borders a zone that is stable to convection. Convective motions can penetrate the boundary between these zones, creating a layer characterized by intermittent convective mixing, and gradual erosion of the density and temperature stratification. Aims: We examine a penetration layer formed between a central radiative zone and a large convection zone in the deep interior of a young low-mass star. Using the Multidimensional Stellar Implicit Code (MUSIC) to simulate two-dimensional compressible stellar convection in a spherical geometry over long times, we produce statistics that characterize the extent and impact of convective penetration in this layer. Methods: We apply extreme value theory to the maximal extent of convective penetration at any time. We compare statistical results from simulations which treat non-local convection, throughout a large portion of the stellar radius, with simulations designed to treat local convection in a small region surrounding the penetration layer. For each of these situations, we compare simulations of different resolution, which have different velocity magnitudes. We also compare statistical results between simulations that radiate energy at a constant rate to those that allow energy to radiate from the stellar surface according to the local surface temperature. Results: Based on the frequency and depth of penetrating convective structures, we observe two distinct layers that form between the convection zone and the stable radiative zone. We show that the probability density function of the maximal depth of convective penetration at any time corresponds closely in space with the radial position where internal waves are excited. We find that the maximal penetration depth can be modeled by a Weibull distribution with a small shape parameter. Using these results, and building on established scalings for diffusion enhanced by large-scale convective motions, we

  1. Toxicity and bioaccumulation of copper in Limnodrilus hoffmeisteri under different pH values: Impacts of perfluorooctane sulfonate.

    Science.gov (United States)

    Meng, Lingjun; Yang, Shaogui; Feng, Mingbao; Qu, Ruijuan; Li, Yong; Liu, Jiaoqin; Wang, Zunyao; Sun, Cheng

    2016-03-15

    Aquatic oligochaete Limnodrilus hoffmeisteri (L. hoffmeisteri) has been commonly used as a lethal and/or sub-lethal toxicological model organism in ecological risk assessments in contaminated water environments. In this study, experiments were conducted to investigate the potential toxic effects of copper (Cu(II)) with or without perfluorooctane sulfonate (PFOS) under different pH values (6.0, 7.0 and 8.0) on LC50, bioaccumulation, and oxidative stress biomarkers in L. hoffmeisteri after 3 and 7 days. The LC50 values of Cu(II) decreased with the increasing pH and the addition of PFOS. After each exposure, increasing bioaccumulation of Cu(II) in L. hoffmeisteri was observed in the combined exposure treatments, whereas the bioaccumulation of PFOS decreased. Moreover, the activity of superoxide dismutase, the level of glutathione, and the content of malondialdehyde were significantly altered after these exposures, possibly indicating that the bioaccumulation of Cu(II) and PFOS caused adverse effects on antioxidant defenses of L. hoffmeisteri. The integrated biomarker response index, indicates that the combined effect was proposed as synergism, which is coincided with the results of toxic unit. Moreover, this work showed that aquatic environment may become more livable when water conditions changed from acidic to near-neutral or alkaline.

  2. Fiber optic sensors for an in-situ monitoring of moisture and pH value in reinforced concrete

    Science.gov (United States)

    Grahn, Walter; Makedonski, Pavel; Wichern, Juergen; Kowalsky, Wolfgang; Wiese, Stefan

    2002-01-01

    Concrete structures such as social buildings and bridges are important economic goods. Thus, maintenance and preservation of these structures are of major interest. Buildings of reinforced concrete are exposed to a variety of damaging influences. In particular, moisture has an important influence on the lifetime of concrete structures. This is caused by the involvement of free water in corrosion of the steel, and the fact that water acts as transport medium for damaging ions such as chloride, sulfate, carbonate and ammonium. Thus, we designed and developed an integrated fiberoptical sensor system, which allows in-situ non- destructive long-term monitoring of concrete structures. As moisture indicator we use a pyridinium-N-phenolat betainital dye, which shows a strong solvatochromic behavior in the ultraviolet-visible spectral range (UV-VIS). The dye is embedded in a polymer matrix, whose moderate polarity is enhanced by free water diffusing into the sensor. This leads to a continuous hypsochromic shift of the absorption spectrum according to the water concetration. Another appropriate dye is 4-amino-N-methylphthalimid, which shows a similar behavior in its fluorescent spectra, and presently we are developing its derivatives and suitable polymer matrices. The determination of the pH-value of concrete is of major importance for the assessment of acidic attacks which may lead to serious damage in reinforced concrete, as the embedded steel structures exhibit long-term stability (i.e. resistance to corrosion) only at pH-values of 9 or higher. Therefore we have developed a fiberoptical sensor system for the measurement of pH-values in concrete consisting of pH- indicator dyes immobilized in a highly immobilized in a highly hydrophilic polymer matrix. Any change in pH-value of the wet concrete material is indicated by a color change of the dye/polymer system. The sensor system displays long term stability even in aggressive media of pH12 - 13.

  3. Influences of Temperature and pH Value on the Corrosion Behaviors of X80 Pipeline Steel in Carbonate/Bicarbonate Buffer Solution

    Institute of Scientific and Technical Information of China (English)

    LI,Jin-Bo; ZUO,Jian-E

    2008-01-01

    The joint effect of temperature and pH value on the corrosion behavior of X80 steel in carbonate/bicarbonate buffer solution was detected by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis. The results show that an unstable corrosion film will be formed on the X80 steel surface in low pH value solutions, and a better protective corrosion film can be formed on the X80 steel surface in high pH value solutions. On the whole, the corrosion film resistance and transfer resistance increase with the increment of pH value, and decrease with increase of solution temperature, which indicates that the protective effect of the corrosion film on X80 steel is enhanced with increasing pH value and decreasing the solution temperature. The corrosion film formed on X80 steel surface in carbonate/bicarbonate buffer solution has an n-type semi-conductive character, and the donor density decreases with increasing the pH value, and increases with increasing the solution temperature. The flat-band potential and pH value have a linear relationship with a positive slope.

  4. Rainfall extremes, weather and climatic characterization over complex terrain: A data-driven approach based on signal enhancement methods and extreme value modeling

    Science.gov (United States)

    Pineda, Luis E.; Willems, Patrick

    2017-04-01

    Weather and climatic characterization of rainfall extremes is both of scientific and societal value for hydrometeorogical risk management, yet discrimination of local and large-scale forcing remains challenging in data-scarce and complex terrain environments. Here, we present an analysis framework that separate weather (seasonal) regimes and climate (inter-annual) influences using data-driven process identification. The approach is based on signal-to-noise separation methods and extreme value (EV) modeling of multisite rainfall extremes. The EV models use a semi-automatic parameter learning [1] for model identification across temporal scales. At weather scale, the EV models are combined with a state-based hidden Markov model [2] to represent the spatio-temporal structure of rainfall as persistent weather states. At climatic scale, the EV models are used to decode the drivers leading to the shift of weather patterns. The decoding is performed into a climate-to-weather signal subspace, built via dimension reduction of climate model proxies (e.g. sea surface temperature and atmospheric circulation) We apply the framework to the Western Andean Ridge (WAR) in Ecuador and Peru (0-6°S) using ground data from the second half of the 20th century. We find that the meridional component of winds is what matters for the in-year and inter-annual variability of high rainfall intensities alongside the northern WAR (0-2.5°S). There, low-level southerly winds are found as advection drivers for oceanic moist of the normal-rainy season and weak/moderate the El Niño (EN) type; but, the strong EN type and its unique moisture surplus is locally advected at lowlands in the central WAR. Moreover, the coastal ridges, south of 3°S dampen meridional airflows, leaving local hygrothermal gradients to control the in-year distribution of rainfall extremes and their anomalies. Overall, we show that the framework, which does not make any prior assumption on the explanatory power of the weather

  5. Continuous measurement of reticuloruminal pH values in dairy cows during the transition period from barn to pasture feeding using an indwelling wireless data transmitting unit.

    Science.gov (United States)

    Gasteiner, J; Horn, M; Steinwidder, A

    2015-04-01

    This study was performed to investigate the effect of the transition from barn feeding to pasture on the pattern of reticuloruminal pH values in 8 multiparous dairy cows. A indwelling wireless data transmitting system for pH measurement was given to 8 multiparous cows orally. Reticuloruminal pH values were measured every 600 s over a period of 42 days. After 7 days of barn feeding (period 1), all of the animals were pastured with increasing grazing times from 2 to 7 h/day over 7 days (period 2). From day 15 to day 21 (period 3), the cows spent 7 h/day on pasture. Beginning on day 22, the animals had 20 h/day access to pasture (day and night grazing). To study reticuloruminal adaptation to pasture feeding, the phase of day and night grazing was subdivided into another 3 weekly periods (periods 4-6). Despite a mild transition period from barn feeding to pasture, significant effects on reticuloruminal pH values were observed. During barn feeding, the mean reticuloruminal pH value for all of the cows was 6.44 ± 0.14, and the pH values decreased significantly (p pH values increased again (pH 6.25 ± 0.22; pH 6.31 ± 0.17; pH 6.37 ± 0.16). Our results showed that the animals had significantly lowered reticuloruminal pH during the periods of feed transition from barn to pasture feeding. Despite these significant changes, the decrease was not harmful, as indicated by data of feed intake and milk production.

  6. A comparison of observed extreme water levels at the German Bight elaborated through an extreme value analysis (EVA) with extremes derived from a regionally coupled ocean-atmospheric climate model (MPI-OM)

    Science.gov (United States)

    Möller, Jens; Heinrich, Hartmut

    2017-04-01

    As a consequence of climate change atmospheric and oceanographic extremes and their potential impacts on coastal regions are of growing concern for governmental authorities responsible for the transportation infrastructure. Highest risks for shipping as well as for rail and road traffic originate from combined effects of extremes of storm surges and heavy rainfall which sometimes lead to insufficient dewatering of inland waterways. The German Ministry of Transport and digital Infrastructure therefore has tasked its Network of Experts to investigate the possible evolutions of extreme threats for low lands and especially for Kiel Canal, which is an important shortcut for shipping between the North and Baltic Seas. In this study we present results of a comparison of an Extreme Value Analysis (EVA) carried out on gauge observations and values derived from a coupled Regional Ocean-Atmosphere Climate Model (MPI-OM). High water levels at the coasts of the North and Baltic Seas are one of the most important hazards which increase the risk of flooding of the low-lying land and prevents such areas from an adequate dewatering. In this study changes in the intensity (magnitude of the extremes) and duration of extreme water levels (above a selected threshold) are investigated for several gauge stations with data partly reaching back to 1843. Different methods are used for the extreme value statistics, (1) a stationary general Pareto distribution (GPD) model as well as (2) an instationary statistical model for better reproduction of the impact of climate change. Most gauge stations show an increase of the mean water level of about 1-2 mm/year, with a stronger increase of the highest water levels and a decrease (or lower increase) of the lowest water levels. Also, the duration of possible dewatering time intervals for the Kiel-Canal was analysed. The results for the historical gauge station observations are compared to the statistics of modelled water levels from the coupled

  7. The transformed-stationary approach: a generic and simplified methodology for non-stationary extreme value analysis

    Science.gov (United States)

    Mentaschi, Lorenzo; Vousdoukas, Michalis; Voukouvalas, Evangelos; Sartini, Ludovica; Feyen, Luc; Besio, Giovanni; Alfieri, Lorenzo

    2016-09-01

    Statistical approaches to study extreme events require, by definition, long time series of data. In many scientific disciplines, these series are often subject to variations at different temporal scales that affect the frequency and intensity of their extremes. Therefore, the assumption of stationarity is violated and alternative methods to conventional stationary extreme value analysis (EVA) must be adopted. Using the example of environmental variables subject to climate change, in this study we introduce the transformed-stationary (TS) methodology for non-stationary EVA. This approach consists of (i) transforming a non-stationary time series into a stationary one, to which the stationary EVA theory can be applied, and (ii) reverse transforming the result into a non-stationary extreme value distribution. As a transformation, we propose and discuss a simple time-varying normalization of the signal and show that it enables a comprehensive formulation of non-stationary generalized extreme value (GEV) and generalized Pareto distribution (GPD) models with a constant shape parameter. A validation of the methodology is carried out on time series of significant wave height, residual water level, and river discharge, which show varying degrees of long-term and seasonal variability. The results from the proposed approach are comparable with the results from (a) a stationary EVA on quasi-stationary slices of non-stationary series and (b) the established method for non-stationary EVA. However, the proposed technique comes with advantages in both cases. For example, in contrast to (a), the proposed technique uses the whole time horizon of the series for the estimation of the extremes, allowing for a more accurate estimation of large return levels. Furthermore, with respect to (b), it decouples the detection of non-stationary patterns from the fitting of the extreme value distribution. As a result, the steps of the analysis are simplified and intermediate diagnostics are

  8. Eye spy: the predictive value of fixation patterns in detecting subtle and extreme emotions from faces.

    Science.gov (United States)

    Vaidya, Avinash R; Jin, Chenshuo; Fellows, Lesley K

    2014-11-01

    Successful social interaction requires recognizing subtle changes in the mental states of others. Deficits in emotion recognition are found in several neurological and psychiatric illnesses, and are often marked by disturbances in gaze patterns to faces, typically interpreted as a failure to fixate on emotionally informative facial features. However, there has been very little research on how fixations inform emotion recognition in healthy people. Here, we asked whether fixations predicted detection of subtle and extreme emotions in faces. We used a simple model to predict emotion detection scores from participants' fixation patterns. The best fit of this model heavily weighted fixations to the eyes in detecting subtle fear, disgust and surprise, with less weight, or zero weight, given to mouth and nose fixations. However, this model could not successfully predict detection of subtle happiness, or extreme emotional expressions, with the exception of fear. These findings argue that detection of most subtle emotions is best served by fixations to the eyes, with some contribution from nose and mouth fixations. In contrast, detection of extreme emotions and subtle happiness appeared to be less dependent on fixation patterns. The results offer a new perspective on some puzzling dissociations in the neuropsychological literature, and a novel analytic approach for the study of eye gaze in social or emotional settings.

  9. [Osmotic modification of thermal damage in Escherichia coli bacteria at various pH values of the media].

    Science.gov (United States)

    Morozov, I I; Petin, V G

    2000-01-01

    A study was made of the influence of media with different osmotic pressure on cell survival and on optic density of supernatants from Escherichia coli B/r and E. coli Bs-1 cell suspensions heated under different pH values of media. Hyperthermia induced cell death accompanied with the loss of optically active (lambda = 260 nm) material. Both cell damage effects were increased in acid and alkaline conditions, compared to neutral condition of heating. Hypertonic media results in a decrease in thermic cell death and loss of cell substances. Under this condition, the protection influence of high osmotic pressure was seen to increase significantly in acid and alkaline conditions of heating, compared to neutral condition. It has been proposed that a higher thermal damage of microorganisms in acid and alkaline beating conditions and protection influence of hypertonic media, especially expressed in acid and alkaline medium, is caused to a great extent by the status of osmotic cell homeostasis.

  10. Utilization of slaked lime for the regulation of pH value in the process of copper

    Directory of Open Access Journals (Sweden)

    Petković Aleksandar V.

    2009-01-01

    Full Text Available The investigations of used lime at plant from company Messer-Tehnogas, Belgrade, were in the aim to improvement technologically results from flotation concentration of copper minerals in flotation plant Veliki Krivelj. This paper shows usage of slaked lime, which is waste in the process of technical gas production, for regulation of pH value in the process of copper minerals flotation concentration. It is important to point out that slaked lime is a waste material that is not dangerous. Preparation and dosage includes preparation procedures, which enable introduction into flotation process with the aim of achieving better results. Lime from Limekiln Zagrađe is brought into four storage places in flotation. Volume of each storage place is 80 m3. Lime in pieces from storage place is added by airbladders on transportation line and by system of transportation lines lime gets to the ball mill. At the mill entrance water is added and then follows lime grinding. Milk glass of lime thus prepared goes to the pump basket from where is transported by pipeline to conditioner, and then by manual and (or automatic valves it is dosed to the flotation concentration of copper minerals process. Prospect of advancement and rationalization of the used lime in flotation plant Bor, Veliki Krivelj and Majdanpek as well as a way to link different branches of industry was demonstrated. Total cost of lime supplying, transporting, preparation and distribution related slaked lime is lower for 2.955 din/kg. Particularly, using lime from Messer in content of 2.1 g/l value of pH 11.82 is possible to obtain.

  11. Glycolytic potential and ultimate muscle pH values in red deer (Cervus elaphus and fallow deer (Dama dama

    Directory of Open Access Journals (Sweden)

    Eva Wiklund

    2004-04-01

    Full Text Available The ultimate pH value of meat (measured at approx. 24 hours post slaughter gives information about the technological quality, i.e. shelf life, colour, water-holding properties and tenderness and is a direct consequence of muscle glycogen (energy levels at slaughter. It may therefore also indicate whether or not the animal has been exposed to stressful energy depleting events prior to slaughter. In the present study, 141 animals (130 red deer (Cervus elaphus and 11 fallow deer (Dama dama were included to investigate the relationship between ultimate pH and residual glycogen concentration in red deer and fallow deer M. longissimus. In addition, the muscle glycogen content and ultimate pH values in three red deer muscles (Mm. triceps brachii, longissimus and biceps femoris were studied. M. triceps brachii had higher ultimate pH and lower glycogen content compared with the other two studied muscles. The frequency of intermediate DFD (5.8≤ pH<6.2 was 5.4% in red deer M. longissimus, compared with 9.1% in fallow deer, while the frequency of DFD (pH≥ 6.2 was much lower in red deer (3.8% than in fallow deer (54.5%. A curvilinear relationship between ultimate pH and total glucose concentration (glycogen and glucose 30 min post slaughter in red deer and fallow deer M. longissimus was found. The relationship between muscle pH and lactic acid concentration however, was indicated to be linear. A significant variation in total glucose concentration at ultimate pH below 5.80 was observed, including values in the range from 18 to 123 mmol/kg wet tissue. It was concluded that further studies are needed to further explore the relationship between muscle glycogen content and technological and sensory quality attributes of meat from different deer species.Abstract in Swedish / Sammanfattning:Köttets pH-värde (mätt ca 24 timmar efter slakt har stor betydelse för den teknologiska kvaliteten som t. ex. hållbarhet, färg, vattenhållande förmåga och m

  12. Comparative Effects of Salt Stress and Extreme pH Stress Combined on Glycinebetaine Accumulation, Photosynthetic Abilities and Growth Characters of Two Rice Genotypes

    Directory of Open Access Journals (Sweden)

    Suriyan CHA-UM

    2009-12-01

    Full Text Available Glycinebetaine (Glybet accumulation, photosynthetic efficiency and growth performance in indica rice cultivated under salt stress and extreme pH stress were investigated. Betaine aldehyde dehydrogenase (BADH activity and Glybet accumulation in the seedlings of salt-tolerant and salt-sensitive rice varieties grown under saline and acidic conditions peaked after treatment for 72 h and 96 h, respectively, and were higher than those grown under neutral pH and alkaline salt stress. A positive correlation was found between BADH activity and Glybet content in both salt-tolerant (r2 = 0.71 and salt-sensitive (r2 = 0.86 genotypes. The chlorophyll a, chlorophyll b, total chlorophyll and total carotenoids contents in the stressed seedlings significantly decreased under both acidic and alkaline stresses, especially in the salt-sensitive genotype. Similarly, the maximum quantum yield of PSII (Fv/Fm, photon yield of PSII (ΦPSII, non-photochemical quenching (NPQ and net photosynthetic rate (Pn in the stressed seedlings were inhibited, leading to overall growth reduction. The positive correlations between chlorophyll a content and Fv/Fm, total chlorophyll content and ΦPSII, ΦPSII and Pn as well as Pn and leaf area in both salt-tolerant and salt-sensitive genotypes were found. Saline acidic and saline alkaline soils may play a key role affecting vegetative growth prior to the reproductive stage in rice plants.

  13. Pitting Corrosion Characterization of Wrought Stellite Alloys in Green Death Solution with Immersion Test and Extreme Value Analysis Model

    Science.gov (United States)

    Zhang, X. Z.; Liu, R.; Chen, K. Y.; Yao, M. X.

    2014-05-01

    This article presents a study of the corrosion behavior of two wrought Stellite alloys, Stellite 6B, and Stellite 6K, in Green Death solution, utilizing the extreme value analysis (EVA) model, which is a statistics tool developed based on the Gumbel distribution. Green Death solution a typical oxidized testing solution used in industry for assessing the corrosion resistance of materials. The data of maximum pit depths are obtained from the immersion tests on these alloys for various exposure periods. The top ten maximum pit depths in each specimen surface after the immersion test are measured using a surface texture and contour measuring instrument. These data are the input parameters of the EVA model and the outcomes of the model are the extreme values (minimum thickness) required for the alloys under a given service condition. It is shown that Stellite 6K, which contains higher carbon content but smaller-size carbides, exhibits better corrosion resistance in regard to the extreme value. The results and mechanisms of Stellite 6B and Stellite 6K in Green Death solution corrosion are discussed.

  14. Cramer-von Mises and Anderson-Darling goodness of fit tests for extreme value distributions with unknown parameters

    Science.gov (United States)

    Laio, Francesco

    2004-09-01

    The use of goodness of fit tests based on Cramer-von Mises and Anderson-Darling statistics is discussed, with reference to the composite hypothesis that a sample of observations comes from a distribution, FH, whose parameters are unspecified. When this is the case, the critical region of the test has to be redetermined for each hypothetical distribution FH. To avoid this difficulty, a transformation is proposed that produces a new test statistic which is independent of FH. This transformation involves three coefficients that are determined using the asymptotic theory of tests based on the empirical distribution function. A single table of coefficients is thus sufficient for carrying out the test with different hypothetical distributions; a set of probability models of common use in extreme value analysis is considered here, including the following: extreme value 1 and 2, normal and lognormal, generalized extreme value, three-parameter gamma, and log-Pearson type 3, in all cases with parameters estimated using maximum likelihood. Monte Carlo simulations are used to determine small sample corrections and to assess the power of the tests compared to alternative approaches.

  15. Effect of glycerol content and pH value of film-forming solution on the functional properties of protein-based edible films

    Directory of Open Access Journals (Sweden)

    Nemet Nevena T.

    2010-01-01

    Full Text Available The work is concerned with the effects of glycerol content and pH value of film forming solution on the functional properties of protein-based films. The films were produced of chicken breast proteins, dissolved under either acidic (pH 3 or alkaline (pH 11 conditions, with different concentrations of glycerol (35%, 50% and 65% w/w of protein content. Glycerol content affected significantly mechanical properties, water vapor permeability, color at pH 3 and film solubility (p<0.05. The pH value had significant influence on light transmission, color, transparency and film solubility (p<0.05. Considering the results of mechanical properties and film solubility, the obtained films are in the acceptable range for the use as a packaging material. It was estimated that water vapor permeability, color, light transmission and transparency need to be improved for the application.

  16. The effect of prolonged immersion of giomer bulk-fill composite resin on the pH value of artificial saliva and resin surface roughness

    Science.gov (United States)

    Ratna, A. A.; Triaminingsih, S.; Eriwati, Y. K.

    2017-08-01

    This study aimed to determine the effect of immersion time on the surface roughness of Giomer Bulk-Fill composite resin and on the pH value of artificial saliva. Sixty-three specimens were divided into nine groups and immersed in artificial saliva with pH values of 7, 5.5, and 4.5 for 1 hour, 24 hours, and 72 hours at 37 °C. The changes in artificial saliva pH were measured using a pH meter and the surface roughness was measured using a surface roughness tester. Longer immersion time increases the pH of artificial saliva and the surface roughness of Giomer Bulk-Fill composite resin.

  17. A Conjecture Regarding the Extremal Values of Graph Entropy Based on Degree Powers

    Directory of Open Access Journals (Sweden)

    Kinkar Chandra Das

    2016-05-01

    Full Text Available Many graph invariants have been used for the construction of entropy-based measures to characterize the structure of complex networks. The starting point has been always based on assigning a probability distribution to a network when using Shannon’s entropy. In particular, Cao et al. (2014 and 2015 defined special graph entropy measures which are based on degrees powers. In this paper, we obtain some lower and upper bounds for these measures and characterize extremal graphs. Moreover we resolve one part of a conjecture stated by Cao et al.

  18. Effect of pH value on particle morphology and electrochemical properties of LiFePO{sub 4} by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Song, Qingzhu, E-mail: qingzhu0812@163.com [Key Laboratory for New Type of Functional Materials in Hebei Province (China); Institute of Power Sources and Eco-Materials Science, Box 1055, Hebei University of Technology, Tianjin 300130 (China); Ou, Xiuqin, E-mail: ouxiuqin@hebut.edu.cn [Key Laboratory for New Type of Functional Materials in Hebei Province (China); Institute of Power Sources and Eco-Materials Science, Box 1055, Hebei University of Technology, Tianjin 300130 (China); Wang, Li, E-mail: tigerwl29@yahoo.com.cn [Key Laboratory for New Type of Functional Materials in Hebei Province (China); Institute of Power Sources and Eco-Materials Science, Box 1055, Hebei University of Technology, Tianjin 300130 (China); Liang, Guangchuan, E-mail: liangguangchuan@hebut.edu.cn [Key Laboratory for New Type of Functional Materials in Hebei Province (China); Institute of Power Sources and Eco-Materials Science, Box 1055, Hebei University of Technology, Tianjin 300130 (China); Wang, Zuorui, E-mail: Bluetianlan001@163.com [Key Laboratory for New Type of Functional Materials in Hebei Province (China); Institute of Power Sources and Eco-Materials Science, Box 1055, Hebei University of Technology, Tianjin 300130 (China)

    2011-09-15

    Graphical abstract: The pH value of system is adjusted in the range of 2.5-8.8 by using dilute sulfuric acid and ammonia water. The results indicated that the particle exhibits acute angle diamond flake-like morphology at pH = 2.5. With increase of pH value, the particle gradually becomes to round flake-like and irregular flake-like morphology. The optimal sample synthesized at pH = 6.4 exhibits discharge capacities of 151.8 mAh g{sup -1} at 0.2 C rate and 129.3 mAh g{sup -1} at 3 C rate. Highlights: {yields} The pH value of solution affects greatly on particle morphology. {yields} The solubility product determined the transition of interphases. {yields} The disorder of atoms in crystal is affected by pH value. {yields} LiFePO{sub 4} with high capacity could be synthesized at slight acid or neutral conditions. -- Abstract: Lithium iron phosphate was prepared by hydrothermal synthesis using LiOH.H{sub 2}O, FeSO{sub 4}.7H{sub 2}O and H{sub 3}PO{sub 4} as raw materials. The effects of pH value of reaction solution on particle morphology and electrochemical property were investigated. The pH value of the reaction solution was adjusted in the range of 2.5-8.8 by dilute sulfuric acid and ammonia water. The samples were characterized by field-emission scanning electronic microscope (FE-SEM), X-ray powder diffraction (XRD), constant-current charge/discharge cycling tests and chemical analysis. The results indicated that the particles exhibited acute angle diamond flake-like morphology at pH = 2.5, and as the pH value increased, the particle became hexagon flake-like, round flake-like and irregular flake-like morphology gradually. The optimal sample synthesized at pH = 6.4 exhibited discharge capacities of 151.8 mAh g{sup -1} at 0.2 C rate and 129.3 mAh g{sup -1} at 3 C rate. It was found that pH value affected the morphologies and properties of the product by means of different crystal growth rates.

  19. Extreme value analysis of annual maximum water levels in the Pearl River Delta, China

    Institute of Scientific and Technical Information of China (English)

    Qiang ZHANG; Chong-Yu XU; Yongqin David CHEN; Chun-ling LIU

    2009-01-01

    We analyzed the statistical properties of water level extremes in the Pearl River Delta using five probability distribution functions. Estimation of para-meters was performed using the L-moment technique.Goodness-of-fit was done based on Kolmogorov-Smirnov's statistic D (K-S D). The research results indicate that Wakeby distribution is the best statistical model for description of statistical behaviors of water level extremes in the study region. Statistical analysis indicates that water levels corresponding to different return periods and associated variability tend to be larger in the landward side of the Pearl River Delta and vice versa. A ridge characterized by higher water level can be identified expanding along the West River and the Modaomen channel, showing the impacts of the hydrologic process of the West River basin. Trough and higher grades of water level changes can be detected in the region drained by Xi'nanyong channel, Dongping channel, and mainstream of Pearl River. The Pearl River Delta region is character-ized by low-lying topography and a highly-advanced socio-economy, and is heavily populated, being prone to flood hazards and flood inundation due to rising sea level and typhoons. Therefore, sound and effective counter-measures should be made for human mitigation to natural hazards such as floods and typhoons.

  20. Modeling nonstationary extreme value distributions with nonlinear functions: An application using multiple precipitation projections for U.S. cities

    Science.gov (United States)

    Um, Myoung-Jin; Kim, Yeonjoo; Markus, Momcilo; Wuebbles, Donald J.

    2017-09-01

    Climate extremes, such as heavy precipitation events, have become more common in recent decades, and nonstationarity concepts have increasingly been adopted to model hydrologic extremes. Various issues are associated with applying nonstationary modeling to extremes, and in this study, we focus on assessing the need for different forms of nonlinear functions in a nonstationary generalized extreme value (GEV) model of different annual maximum precipitation (AMP) time series. Moreover, we suggest an efficient approach for selecting the nonlinear functions of a nonstationary GEV model. Based on observed and multiple projected AMP data for eight cities across the U.S., three separate tasks are proposed. First, we conduct trend and stationarity tests for the observed and projected data. Second, AMP series are fit with thirty different nonlinear functions, and the best functions among these are selected. Finally, the selected nonlinear functions are used to model the location parameter of a nonstationary GEV model and stationary and nonstationary GEV models with a linear function. Our results suggest that the simple use of nonlinear functions might prove useful with nonstationary GEV models of AMP for different locations with different types of model results.

  1. Investigation on the Key Factors and the Solution for pH Value Decrease in Carbon Filter in O3-BAC Process

    Institute of Scientific and Technical Information of China (English)

    陆少鸣; 陈江玲; 李芳

    2013-01-01

    An investigation was carried out to eliminate the decrease of effluent pH value in carbon filter in O3-biological activated carbon process. The influence factors were examined in a pilot test, and pH was adjusted in the pilot and waterworks. Results show that the carbon filter is an acid-base buffer system and the activated carbon is the key factor. Chemical functional groups on activated carbon surface present acid-base properties to buffer the water but decrease with time, so that effluent pH value decreases. The effects of ozone dosage, CO2 in the carbon filter, and the filter influent quality are negligible. A new method to adjust pH is developed:the activated carbon is first modified by soaking in sodium hydroxide solution to make its pH reach the desired value, and then the pH value of inflow is controlled to certain value by dosing lime in sand filter influent. The method is economical and effective.

  2. Influence of bath PH value on microstructure and corrosion resistance of phosphate chemical conversion coating on sintered Nd-Fe-B permanent magnets

    Science.gov (United States)

    Ding, Xia; Xue, Long-fei; Wang, Xiu-chun; Ding, Kai-hong; Cui, Sheng-li; Sun, Yong-cong; Li, Mu-sen

    2016-10-01

    The effect of bath PH value on formation, microstructure and corrosion resistance of the phosphate chemical conversion (PCC) coatings as well as the effect on the magnetic property of the magnets is investigated in this paper. The results show that the coating mass and thickness increase with the decrease of the bath PH value. Scanning electron microscopy observation demonstrates that the PCC coatings are in a blocky structure with different grain size. Transmission electron microscope and X-ray diffractometer tests reveal the coatings are polycomponent and are mainly composed of neodymium phosphate hydrate and praseodymium phosphate hydrate. The electrochemical analysis and static immersion corrosion test show the corrosion resistance of the PCC coatings prepared at bath PH value of 0.52 is worst. Afterwards the corrosion resistance increases first and then decreases with the increasing of the bath PH values. The magnetic properties of all the samples with PCC treatment are decreased. The biggest loss is occurred when the bath PH value is 0.52. Taken together, the optimum PH range of 1.00-1.50 for the phosphate solution has been determined.

  3. Non-linear time series extreme events and integer value problems

    CERN Document Server

    Turkman, Kamil Feridun; Zea Bermudez, Patrícia

    2014-01-01

    This book offers a useful combination of probabilistic and statistical tools for analyzing nonlinear time series. Key features of the book include a study of the extremal behavior of nonlinear time series and a comprehensive list of nonlinear models that address different aspects of nonlinearity. Several inferential methods, including quasi likelihood methods, sequential Markov Chain Monte Carlo Methods and particle filters, are also included so as to provide an overall view of the available tools for parameter estimation for nonlinear models. A chapter on integer time series models based on several thinning operations, which brings together all recent advances made in this area, is also included. Readers should have attended a prior course on linear time series, and a good grasp of simulation-based inferential methods is recommended. This book offers a valuable resource for second-year graduate students and researchers in statistics and other scientific areas who need a basic understanding of nonlinear time ...

  4. Optimizing isothiocyanate formation during enzymatic glucosinolate breakdown by adjusting pH value, temperature and dilution in Brassica vegetables and Arabidopsis thaliana

    Science.gov (United States)

    Hanschen, Franziska S.; Klopsch, Rebecca; Oliviero, Teresa; Schreiner, Monika; Verkerk, Ruud; Dekker, Matthijs

    2017-01-01

    Consumption of glucosinolate-rich Brassicales vegetables is associated with a decreased risk of cancer with enzymatic hydrolysis of glucosinolates playing a key role. However, formation of health-promoting isothiocyanates is inhibited by the epithiospecifier protein in favour of nitriles and epithionitriles. Domestic processing conditions, such as changes in pH value, temperature or dilution, might also affect isothiocyanate formation. Therefore, the influences of these three factors were evaluated in accessions of Brassica rapa, Brassica oleracea, and Arabidopsis thaliana. Mathematical modelling was performed to determine optimal isothiocyanate formation conditions and to obtain knowledge on the kinetics of the reactions. At 22 °C and endogenous plant pH, nearly all investigated plants formed nitriles and epithionitriles instead of health-promoting isothiocyanates. Response surface models, however, clearly demonstrated that upon change in pH to domestic acidic (pH 4) or basic pH values (pH 8), isothiocyanate formation considerably increases. While temperature also affects this process, the pH value has the greatest impact. Further, a kinetic model showed that isothiocyanate formation strongly increases due to dilution. Finally, the results show that isothiocyanate intake can be strongly increased by optimizing the conditions of preparation of Brassicales vegetables.

  5. Mandelbrot's Extremism

    NARCIS (Netherlands)

    Beirlant, J.; Schoutens, W.; Segers, J.J.J.

    2004-01-01

    In the sixties Mandelbrot already showed that extreme price swings are more likely than some of us think or incorporate in our models.A modern toolbox for analyzing such rare events can be found in the field of extreme value theory.At the core of extreme value theory lies the modelling of maxima

  6. Use of Generalized Extreme Value Covariates to Improve Estimation of Trends and Return Frequencies for Lake Levels

    Science.gov (United States)

    Paynter, S.; Nachabe, M.

    2008-12-01

    One of the most important tools in water management is the accurate forecast of both long-term and short- term extreme values for both flood and drought conditions. Traditional methods of trend detection, such as ordinary least squares (OLS) or the Mann-Kendall test, are not aptly suited for hydrologic systems while traditional methods of predicting extreme flood and drought frequencies, such as distribution fitting without parameter covariates, may be highly inaccurate in lake-type systems, especially in the short-term. In the case of lakes, traditional frequency return estimates assume extremes are independent of trend or starting lake stages. However, due to the significant autocorrelation of lake levels, the initial stage can have a significant influence on the severity of a given event. The aim of this research was to accurately identify the direction and magnitude of trends in flood and drought stages and provide more accurate predictions of both long-term and short-term flood and drought stage return frequencies utilizing the generalized extreme value distribution with time and starting stage covariates. All of the lakes researched evidenced either no trend or very small trends unlikely to significantly alter prediction of future flood or drought return levels. However, for all of the lakes significant improvement in the prediction of extremes was obtained with the inclusion of starting lake stage as a covariate. Traditional methods of predicting flood or drought stages significantly overpredict stages when starting lake stages are low and underpredict stages when starting stages are high. The difference between these predictions can be nearly two meters, a significant amount in urbanized watersheds in areas of the world with flat topography. Differences of near two meters can mean significant alterations in evacuation or other water management decisions. In addition to improving prediction of extreme events, utilizing GEV with time or starting stage

  7. Future trend of extreme value distributions of wintertime surface air temperatures over Korea and the associated physical changes

    Science.gov (United States)

    Kim, Kwang-Yul; Kim, Ji-Won; Kim, Maeng-Ki; Cho, Chun-Ho

    2013-11-01

    Daily winter temperatures in Korea have been analyzed via CSEOF analysis. Then, each PC time series was detrended and was fitted to an AR (autoregressive) model. Based on the identified AR model, an artificial time series of arbitrary length can be generated by using an arbitrary white-noise time series. In this way, one hundred new sets of PC time series were generated over the period of 1973-2058. Then, the trend for each PC time series was added back to the artificial PC time series extending the trend until 2058. Ultimately, artificial daily winter temperatures in Korea have been constructed by using the artificial PC time series and the original loading vectors derived from the observational data. The 100 new data sets have been investigated in order to understand the winter temperature variability 50 years into the future. Regression analysis in CSEOF space shows that temperature increase in Korea is associated with increased 850-hPa air temperature over most of the Asian domain (97°-153°E × 22°-73°N) and increased 850-hPa geopotential height in the southern part of the domain. As a result, southerly and southeasterly wind anomalies develop carrying positive temperature anomalies northward and northwestward. Both the 200-hPa air temperature and geopotential height changes indicate that there will be fairly significant northward shift of the jet stream in future. The standard deviation of the 200-hPa potential vorticity increases implying that shortwave trough and henceforth baroclinic instability will increase in future. Finally, GEV (Generalized Extreme Value) distribution and GPD (Generalized Pareto distribution) distribution have been compared between the observational records and the future records of the same length. The extreme value distributions based on the synthetic datasets show that warm extreme events will be more extreme in future and cold extreme events, on the other hand, will be less extreme. This study provides an estimate of future

  8. Tolerance of the widespread cyanobacterium Nostoc commune to extreme temperature variations (-269 to 105°C), pH and salt stress.

    Science.gov (United States)

    Sand-Jensen, Kaj; Jespersen, Thomas Sand

    2012-06-01

    Nostoc commune is a widespread colonial cyanobacterium living on bare soils that alternate between frost and thaw, drought and inundation and very low and high temperatures. We collected N. commune from alternating wet and dry limestone pavements in Sweden and tested its photosynthesis and respiration at 20°C after exposure to variations in temperature (-269 to 105°C), pH (2-10) and NaCl (0.02-50 g NaCl kg(-1)). We found that dry field samples and rewetted specimens tolerated exposure beyond that experienced in natural environmental conditions: -269 to 70°C, pH 3-10 and 0-20 g NaCl kg(-1), with only a modest reduction of respiration, photosynthesis and active carbon uptake at 20°C. (14)CO(2) uptake from air declined markedly below zero and above 55°C, but remained positive. Specimens maintained a high metabolism with daily exposure to 6 h of rehydration and 18 h of desiccation at -18 and 20°C, but died at 40°C. The field temperature never exceeded the critical 40°C threshold during the wet periods, but it frequently exceeded this temperature during dry periods when N. commune is already dry and unaffected. We conclude that N. commune has an excellent tolerance to low temperatures, long-term desiccation and recurring cycles of desiccation and rewetting. These traits explain why it is the pioneer species in extremely harsh, nutrient-poor and alternating wet and dry environments.

  9. Stability of the calcium hydroxyzincate protective layer developed on galvanized reinforcements after a further increase of the pH value

    OpenAIRE

    Andrade, C.; Macías, A

    1986-01-01

    In previous works on galvanized reinforcements in contact with Ca- containing highly alkaline media, the authors have reported the existence of a threshold pH of 13,3 ± 0,1, below which the Zn in contact with such a medium is passivated by formation of a continuous layer of calcium hydroxyzincate, but at pH values above this it corrodes continuously until it totally disappears. The investigation on the stability of the calcium hydroxyzincate layer after an increase of the pH to very high...

  10. Investigation of the adsorption of anionic surfactants at different pH values by means of active carbon and the kinetics of adsorption

    OpenAIRE

    2004-01-01

    In this study, the effect of pH on the removal of anionic surfactants, such as linear alkyl benzene sulfonate (LABS) and dodecyl benzene sulfonate (DBS) by means of adsorption by activated carbon was investigated. For this purpose activated carbon was used as adsorbent. Anionic surfactant solutions with initial pH values of 3, 6, 8 and 12 were used. The adsorption isotherms for the adsorption of anionic surfactants by active carbon at different pH were determined. These adsorption isotherms w...

  11. Effect of dipping solution pH values on electrostatic layer-by-layer self-assembly of side-chain azo polyelectrolyte

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effect of pH value on the electrostatic layer-by-layer self-assembly and the photo-responsive behavior of Poly{2-[4-(4-ethoxyphenylazo)phenoxy]ethyl acrylate-co-acrylic acid} (PEAPE) was studied.Results show that in the studied pH value range,the lower the pH value is,the higher is the UV-vis absorbance and the larger is the thickness of the multilayer films.FTIR studies indicate that the azo polyelectrolyte exhibits a different ionization degree in solutions with different pH values.The higher absorbance and the larger thickness of the layer-by-layer films can be attributed to the low ionization degree and the shrinkage conformation of PEAPE in the solution with low pH values.FTIR analysis also confirms that the driving force for layer-by-layer self-assembly of PEAPE and PDAC is the electrostatic interaction.

  12. Ex situ and in situ AFM investigations on the growth of the (100) face of KDP with different pH values

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Through investigations on the growth of the (100) face of potassium dihydrogen phosphate (KDP) crystal by ex situ atomic force microscopy (AFM) with different pH values at different supersaturations at 40°C,it was found that the growth of crystal was controlled by step flow at lower supersaturations,and the morphologies of steps were different under different growth conditions.In addition,at the higher supersaturations,2D nucleation mechanism controlled the growth.When the supersaturations were lower,the dislocation mechanism controlled the growth of crystal,and when σ≥0.05,2D nucleation mechanism played a dominant role in the growth of the (100) face for pH=4.2 and pH=2.5.However,for pH=5.0,the dislocation mechanism also dominated the growth of crystal when the supersaturations were lower,but when σ≥0.03,the crystal growth was controlled by 2D nucleation mechanism.Through investigations on the step flow of the (100) face of KDP crystal by in situ AFM with different pH values at lower supersaturations at 25°C,the velocities of normal growth of the (100) face were estimated at different growth conditions by in situ AFM.It was found that when the pH value was 5.0,the normal growth rate was the fastest at the same supersaturation compared to the other pH values and screw dislocation mechanism controlled the crystal growth.In addition,we found that with the reduction of the supersaturation of the solution,the density of steps also decreased,the width of steps became larger.Finally,a phenomenon which was the obvious anisotropic growth of steps in the step flow was observed by in situ AFM at σ=0.025 at pH=5.0.

  13. Extreme-value time-series analysis of Australian Region A gust wind speeds to examine instrument bias

    Science.gov (United States)

    Cechet, R. P.; Sanabria, L. A.

    2010-08-01

    Australian building codes through the Australia/New Zealand Wind Actions Standard as well as the wind engineering community in general rely to a significant extent on the peak gust wind speed observations collected over more than 70 years by the Australian Bureau of Meteorology (BoM). In the mid-1980's BoM commenced a program to replace the aging pressure tube Dines anemometers with cup anemometers. During the replacement procedure, many localities had more than one type of anemometer operating, recording extreme events. Systematic differences between instrument measurements during this overlap period raised serious concerns about the utility of the peak gust wind speed database. This paper presents the results of a reanalysis of the current BoM peak wind gust database for the non-cyclonic region (Region A) of the Australia/New Zealand Wind Actions Standard. The study utilises extreme value distribution analysis and compares estimates of the 500-year return-period (RP) peak gust wind exceedance level derived from segments of the record measured with the Dines and replacement anemometers. Results indicate that the later period appears to have a significant reduction in extreme events; 17 of 31 sites have a mean 500 year RP exceedance level for the replacement anemometer section of the record below the lower 95% confidence limit for the Dines anemometer part of the record. The 3PM mean wind speed time-series observations have also been examined, and they exhibit a similar trend.

  14. Kinetics of an acid-base catalyzed reaction (aspartame degradation) as affected by polyol-induced changes in buffer pH and pK values.

    Science.gov (United States)

    Chuy, S; Bell, L N

    2009-01-01

    The kinetics of an acid-base catalyzed reaction, aspartame degradation, were examined as affected by the changes in pH and pK(a) values caused by adding polyols (sucrose, glycerol) to phosphate buffer. Sucrose-containing phosphate buffer solutions had a lower pH than that of phosphate buffer alone, which contributed, in part, to reduced aspartame reactivity. A kinetic model was introduced for aspartame degradation that encompassed pH and buffer salt concentrations, both of which change with a shift in the apparent pK(a) value. Aspartame degradation rate constants in sucrose-containing solutions were successfully predicted using this model when corrections (that is, lower pH, lower apparent pK(a) value, buffer dilution from the polyol) were applied. The change in buffer properties (pH, pK(a)) from adding sucrose to phosphate buffer does impact food chemical stability. These effects can be successfully incorporated into predictive kinetic models. Therefore, pH and pK(a) changes from adding polyols to buffer should be considered during food product development.

  15. Influences of pH value in deposition-precipitation synthesis process on Pt-doped TiO2 catalysts for photocatalytic oxidation of NO

    Institute of Scientific and Technical Information of China (English)

    Shuzhen Song; Zhongyi Sheng; Yue Liu; Haiqiang Wang; Zhongbiao Wu

    2012-01-01

    This work has been undertaken to study the influences of pH value on the characteristics and activity of photocatalyst by deposition-precipitation method during its preparation process.A series of Pt-modified TiO2 were prepared by deposition-precipitation method at different pH values as well as wet impregnation method,and characterized by XRD,XPS,TEM,UV-Vis and photoluminescence(PL).It was found that the catalysts had the highest photocatalytic activity for NO conversion when pH value was kept at around 7.And the sample prepared by deposition-precipitation method showed higher activity than that by impregnation method.This was mainly due to their high value in highly-dispersed platinum oxides(PtOx)content on the surface of the catalysts.The results from UV-Vis absorption showed that highest absorbance was obtained for Pt/TiO2 prepared at pH values of around 7.And PL spectra results indicated that the recombination rate of photogenerated electrons and holes of the samples prepared by deposition-precipitation method was lower than that prepared by impregnation method.And in the zeta potential study,the pH values for the isoelectric point of the preparing slurry of 0.05 wt.%Pt/TiO2 and 0.5 wt.%Pt/TiO2 were determined to be 6.5-8.5,which further confirmed the enrichment of PtOx dopants for the catalysts repapered when pH value was around 7.

  16. [Short-term changes of pH value and Al activity in acid soils after urea fertilization].

    Science.gov (United States)

    Zeng, Qingru; Liao, Bohan; Jiang, Zhaohui; Zhou, Xihong; Tang, Can; Zhong, Ning

    2005-02-01

    Acidic soils are widely distributed in South China, and their acidity is the major environmental stress factor limiting the growth of most crops. It is well known that soil Al solubilized at low pH is a main toxic factor for plant growth. Our study with three acidic soils showed that soil pH increased quickly, while soil exchangeable Al decreased sharply with the increasing concentrations of applied urea. The time-course experiment revealed that the increase of soil pH was short-lived, with a subsequently slow drop after reached its maximum. Urea fertilization caused a drastic change of soil pH during 2-4 weeks of the experimental period. There was a negative relationship between soil pH and soil exchangeable Al. Biological toxicity test demonstrated that applying urea to acidic soils could obviously decrease the aluminum toxicity of maize in a short-term period.

  17. A Statistical Methodology for Determination of Safety Systems Actuation Setpoints Based on Extreme Value Statistics

    Directory of Open Access Journals (Sweden)

    D. R. Novog

    2008-01-01

    Full Text Available This paper provides a novel and robust methodology for determination of nuclear reactor trip setpoints which accounts for uncertainties in input parameters and models, as well as accounting for the variations in operating states that periodically occur. Further it demonstrates that in performing best estimate and uncertainty calculations, it is critical to consider the impact of all fuel channels and instrumentation in the integration of these uncertainties in setpoint determination. This methodology is based on the concept of a true trip setpoint, which is the reactor setpoint that would be required in an ideal situation where all key inputs and plant responses were known, such that during the accident sequence a reactor shutdown will occur which just prevents the acceptance criteria from being exceeded. Since this true value cannot be established, the uncertainties in plant simulations and plant measurements as well as operational variations which lead to time changes in the true value of initial conditions must be considered. This paper presents the general concept used to determine the actuation setpoints considering the uncertainties and changes in initial conditions, and allowing for safety systems instrumentation redundancy. The results demonstrate unique statistical behavior with respect to both fuel and instrumentation uncertainties which has not previously been investigated.

  18. Extremely supercharged proteins in mass spectrometry: profiling the pH of electrospray generated droplets, narrowing charge state distributions, and increasing ion fragmentation.

    Science.gov (United States)

    Zenaidee, Muhammad A; Donald, William A

    2015-03-21

    The effects of 12 acids, 4 solvents, and 8 low-volatility additives that increase analyte charging (i.e., superchargers) on the charge state distributions (CSDs) of protein ions in ESI-MS were investigated. We discovered that (i) relatively low concentrations [5% (v/v)] of 1,2-butylene carbonate (and 4-vinyl-1,3-dioxolan-2-one) can be added to ESI solutions to form higher charge states of cytochrome c and myoglobin ions than by using more traditional additives (e.g., propylene carbonate, sulfolane, or m-nitrobenzyl alcohol) under these conditions and (ii) the width of CSDs narrow as the effectiveness of superchargers increase, which concentrates protein ions into fewer detection channels. The use of strong acids (pKa values protein supercharging, higher adduction of acid molecules, and wider CSDs for many superchargers and proteins, whereas the use of weak acids (pKa > 0) results in significantly higher protein ion charging, less acid adduction, and narrower CSDs, indicating that protein ion supercharging in ESI can be significantly limited by the binding of conjugate base anions of acids that neutralize charge sites and broaden CSDs. The extent of protein charging as a function of acid identity (HA) does not strongly correlate with gas-phase proton transfer data (i.e., gas-phase basicity and proton affinity values for HA and A(-)), solution-phase protein secondary structures (as determined by circular dichroism spectroscopy), and/or acid molecule volatility data. For protein-denaturing solutions, these data were used to infer that the "effective" pH of ESI generated droplets near the moment of ion formation can be ∼0, which is ca. 1 to 3 pH units lower than the pH of the solutions prior to ESI. Electron capture dissociation (ECD) of [ubiquitin, 17H](17+) resulted in the identification of 223 cleavages, 74 of 75 inter-residue sites, and 92% ECD fragmentation efficiency, which correspond to highest of these values that have been obtained by ECD of a single

  19. 废水处理中pH值的PLC自动控制系统%PLC automatic control system of pH value in wastewater treatment.

    Institute of Scientific and Technical Information of China (English)

    李安峰; 张志群; 丁庭华; 王绍堂

    2001-01-01

    The pH value automatic control is a key link in the treatment of industrial wastewater. Based on much literature review, a new PLC automatic control system, suitable for pH value control in the wastewater treatment, is developed with simple structure and good control effect, which offers a practical approach for pH value automatic control in the treatment of industrial wastewater.%pH值自动控制是工业废水处理过程中的关键环节.在查阅大量文献的基础上,研究出一套新的适于污水处理pH值控制的结构简单且控制效果良好的PLC自动控制系统,为工业废水处理的pH值自动控制提供了一条切实可行的途径.

  20. Effect of pH value of poly(ethylenimine)-H 2SO 4 electrolyte on electrochromic response of polyaniline thin films

    Science.gov (United States)

    Hu, Hailin; Ortíz-Aguilar, Blanca E.; Hechavarría, Liliana

    2007-02-01

    Electrochromic devices (ECDs) are electrochemical cells with one or two electrochemically active coatings that change color during the reduction-oxidation process. In this work an electrochromic polyaniline (PANI) thin film and a viscous electrolyte, formed by mixing a basic aqueous solution of polyethylenimine (PEI) and concentrated sulfuric acid (H 2SO 4), have been used as the main components of an ECD. The pH value of the electrolyte is a function of the relative proportion between PEI and H 2SO 4. Fourier transform infrared spectroscopy (FT-IR) results show that for those PEI-H 2SO 4 complexes of pH value varied from 2 to 9 sulfate ions of the inorganic acid are associated to the imine groups of PEI. If the pH value of the same system is lower than or equal to 1, HSO4- anions appear in the electrolyte together with a notable reduction of the free water content. Electrochemical impedance spectroscopy study of these electrolytes show that the protonic conductivity of the PEI-H 2SO 4 complex with pH 1 is almost three orders of magnitude lower than that of the same electrolytes but with a pH value between 2 and 6. Optical switch speed of a PANI/PEI-H 2SO 4 based ECD at 550 nm under a square potential application of +1.2 V and -1.2 V is proportional to the ionic conductivity of the electrolyte of the device.

  1. Estimation of Dynamic VaR in Chinese Stock Markets Based on Time Scale and Extreme Value Theory

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The accuracy and time scale invariance of value-at-risk (VaR) measurement methods for different stock indices and at different confidence levels are tested. Extreme value theory (EVT) is applied to model the extreme tail of standardized residual series of daily/weekly indices losses, and parametric and nonparametric methods are used to estimate parameters of the general Pareto distribution (GPD), and dynamic VaR for indices of three stock markets in China. The accuracy and time scale invariance of risk measurement methods through back-testing approach are also examined. Results show that not all the indices accept time scale invariance; there are some differences in accuracy between different indices at various confidence levels. The most powerful dynamic VaR estimation methods are EVT-GJR-Hill at 97.5% level for weekly loss to Shanghai stock market, and EVT-GARCH-MLE (Hill) at 99.0% level for weekly loss to Taiwan and Hong Kong stock markets, respectively.

  2. Crescimento de Bradyrhizobium elkanii estirpe Br 29 em meios de cultivo com diferentes valores de pH inicial Growth of Bradyrhizobium elkanii strain Br 29 in culture media with different pH values

    Directory of Open Access Journals (Sweden)

    Alexandre Barberi

    2004-04-01

    obtained or if tolerance to acidity could be induced. Some papers demonstrated induced tolerance to acidity when the bacterium is previously exposed to a slightly acid pH. The aim of this study was to verify the growth of Bradyrhizobium elkanii strain Br 29 in culture media with different pH values (6.8; 6.0; 5.5. Two experiments were carried out with two different culture media varying mainly regarding initial pH. Strain growth, by optical density and colony forming units (CFU number, and pH medium modification were evaluated. Growth curves varied either in accordance with pH or culture media composition. Growth based on maximum number of CFU.mL-1 was better at pH 5.5 in Lopreto medium and at pH 6.0 at Lorda and Balatti medium. Better growth on lowest pH (5.5 was related to greater exopolyssacaride production.

  3. Stabilization of Organic Matter by Biochar Application in Compost-amended Soils with Contrasting pH Values and Textures

    Directory of Open Access Journals (Sweden)

    Shih-Hao Jien

    2015-09-01

    Full Text Available Food demand and soil sustainability have become urgent concerns because of the impacts of global climate change. In subtropical and tropical regions, practical management that stabilizes and prevents organic fertilizers from rapid decomposition in soils is necessary. This study conducted a short-term (70 days incubation experiment to assess the effects of biochar application on the decomposition of added bagasse compost in three rural soils with different pH values and textures. Two rice hull biochars, produced through slow pyrolization at 400 °C (RHB-400 and 700 °C (RHB-700, with application rates of 1%, 2%, and 4% (w/w, were separately incorporated into soils with and without compost (1% (w/w application rate. Experimental results indicated that C mineralization rapidly increased at the beginning in all treatments, particularly in those involving 2% and 4% biochar. The biochar addition increased C mineralization by 7.9%–48% in the compost-amended soils after 70 days incubation while the fractions of mineralized C to applied C significantly decreased. Moreover, the estimated maximum of C mineralization amount in soils treated with both compost and biochar were obviously lower than expectation calculated by a double exponential model (two pool model. Based on the micromorphological observation, added compost was wrapped in the soil aggregates formed after biochar application and then may be protected from decomposing by microbes. Co-application of compost with biochar may be more efficient to stabilize and sequester C than individual application into the studied soils, especially for the biochar produced at high pyrolization temperature.

  4. Assessment of Coastal and Urban Flooding Hazards Applying Extreme Value Analysis and Multivariate Statistical Techniques: A Case Study in Elwood, Australia

    Science.gov (United States)

    Guimarães Nobre, Gabriela; Arnbjerg-Nielsen, Karsten; Rosbjerg, Dan; Madsen, Henrik

    2016-04-01

    Traditionally, flood risk assessment studies have been carried out from a univariate frequency analysis perspective. However, statistical dependence between hydrological variables, such as extreme rainfall and extreme sea surge, is plausible to exist, since both variables to some extent are driven by common meteorological conditions. Aiming to overcome this limitation, multivariate statistical techniques has the potential to combine different sources of flooding in the investigation. The aim of this study was to apply a range of statistical methodologies for analyzing combined extreme hydrological variables that can lead to coastal and urban flooding. The study area is the Elwood Catchment, which is a highly urbanized catchment located in the city of Port Phillip, Melbourne, Australia. The first part of the investigation dealt with the marginal extreme value distributions. Two approaches to extract extreme value series were applied (Annual Maximum and Partial Duration Series), and different probability distribution functions were fit to the observed sample. Results obtained by using the Generalized Pareto distribution demonstrate the ability of the Pareto family to model the extreme events. Advancing into multivariate extreme value analysis, first an investigation regarding the asymptotic properties of extremal dependence was carried out. As a weak positive asymptotic dependence between the bivariate extreme pairs was found, the Conditional method proposed by Heffernan and Tawn (2004) was chosen. This approach is suitable to model bivariate extreme values, which are relatively unlikely to occur together. The results show that the probability of an extreme sea surge occurring during a one-hour intensity extreme precipitation event (or vice versa) can be twice as great as what would occur when assuming independent events. Therefore, presuming independence between these two variables would result in severe underestimation of the flooding risk in the study area.

  5. Influence of salts and pH on growth and activity of a novel facultatively alkaliphilic, extremely salt-tolerant, obligately chemolithoautotrophic sufur-oxidizing Gammaproteobacterium Thioalkalibacter halophilus gen. nov., sp. nov. from South-Western Siberian soda lakes

    NARCIS (Netherlands)

    Banciu, H.L.; Sorokin, D.Y.; Tourova, T.P.; Galinski, E.A.; Muntyan, M.S.; Kuenen, J.G.; Muyzer, G.

    2008-01-01

    A chemolithoautotrophic sulfur-oxidizing bacterium (SOB) strain ALCO 1 capable of growing at both near-neutral and extremely alkaline pH was isolated from hypersaline soda lakes in S-W Siberia (Altai, Russia). Strain ALCO 1 represents a novel separate branch within the halothiobacilli in the Gammapr

  6. Influence of salts and pH on growth and activity of a novel facultatively alkaliphilic, extremely salt-tolerant, obligately chemolithoautotrophic sufur-oxidizing Gammaproteobacterium Thioalkalibacter halophilus gen. nov., sp. nov. from South-Western Siberian soda lakes

    NARCIS (Netherlands)

    Banciu, H.L.; Sorokin, D.Y.; Tourova, T.P.; Galinski, E.A.; Muntyan, M.S.; Kuenen, J.G.; Muyzer, G.

    2008-01-01

    A chemolithoautotrophic sulfur-oxidizing bacterium (SOB) strain ALCO 1 capable of growing at both near-neutral and extremely alkaline pH was isolated from hypersaline soda lakes in S-W Siberia (Altai, Russia). Strain ALCO 1 represents a novel separate branch within the halothiobacilli in the

  7. Standard practice for extreme value analysis of nonmetallic inclusions in steel and other microstructural features

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This practice describes a methodology to statistically characterize the distribution of the largest indigenous nonmetallic inclusions in steel specimens based upon quantitative metallographic measurements. The practice is not suitable for assessing exogenous inclusions. 1.2 Based upon the statistical analysis, the nonmetallic content of different lots of steels can be compared. 1.3 This practice deals only with the recommended test methods and nothing in it should be construed as defining or establishing limits of acceptability. 1.4 The measured values are stated in SI units. For measurements obtained from light microscopy, linear feature parameters shall be reported as micrometers, and feature areas shall be reported as micrometers. 1.5 The methodology can be extended to other materials and to other microstructural features. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish app...

  8. [Effects of pH value on the adsorption and degradation of 2, 4-DCP by nanoscale zero-valent iron].

    Science.gov (United States)

    Feng, Li; Ge, Xiao-Peng; Wang, Dong-Sheng; Tang, Hong-Xiao

    2012-01-01

    To evaluate the effect of pH on the degradation of 2,4-DCP by zero-valent iron nanoparticles (with the particle size of 30-40 nm in diameter) samples were taken for TEM, SEM-EDX, and ICP-OES analysis and investigated on the particle morphology changes and 2,4-DCP removal under different pH conditions. It is shown that iron nanoparticles agglomerate from individual particles and tiny clusters into massive aggregate assemblies with their surfaces oxidized and coated by the needle-like rotten iron oxide products (FeOOH) in the degradation process, which will block up a further reaction of 2,4-DCP dechlorination, while the low pH value condition in acidic system can effectively suppress particles aggregation and the surface oxidation, although iron loss in the solid phase is somehow inevitable. Large quantity of Fe2+ ions soaked out from iron nanoparticles significantly promote 2,4-DCP removal by reduction, and the solution pH tends to go up in the reaction process. Acidic conditions facilitate 2,4-DCP dechlorination, and the removal efficiency became higher with the pH reduced, in which 90% of 2,4-DCP removal is reached in 24 h under the pH value of 3.

  9. Proposal of a New SI Base Unit for Value. An Hedonic Estimation of the Physical Purchasing Power (PhPP) of Money.

    Science.gov (United States)

    Defilla, Steivan

    2006-03-01

    Hitherto, the purchasing power of money, i.e. its transaction value, has been measured in terms of inflation index numbers and consumer baskets. Consumer baskets are variable phenomena and their use as measurement units for value confuses the measuring with the measurand. We propose an invariant numeraire, or value unit, based on the market value of a Planck energy (1956 MJ). Planck units form a natural system of units independent of any civilization. The hedonic estimation of the PhPP of a currency differentiates energy by product as well as by thermodynamic quality (exergy). Following SI rules, we propose to name the value unit walras (Wal) in honour of the economist Leon Walras (1834 - 1910). One Wal can also be interpreted as the minimum cost of physiological life of a reference person during one year. The study uses official disaggregated Swiss Producer and Consumer Price Index data and estimates the PhPP of the Swiss franc in 2003.

  10. Variation in structural and dielectric properties of co-precipitated nanoparticles strontium ferrites due to value of pH

    Energy Technology Data Exchange (ETDEWEB)

    Anis-ur-Rehman, M., E-mail: marehman@comsats.edu.pk [Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan); Asghar, G. [Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

    2011-01-12

    Nanoparticles of strontium ferrites with nominal composition SrFe{sub 12}O{sub 19} were prepared by co-precipitation method, by decreasing pH from 13 to 8 with a regular step of 1. The secondary phase of {alpha}-Fe{sub 2}O{sub 3} was increased with the decrease in pH. The crystallite size estimated from X-rays diffraction data was in the range 52-70 nm, which is much smaller than that already reported. Most of the particles formed had hexagonal structure, as observed by the scanning electron microscopy. Particle size and dielectric loss were increased where as dc electrical resistivity and dielectric constant were decreased with decrease in pH. The results show that the material synthesized with higher pH is phase pure and is potentially more suitable for high frequency applications.

  11. Heat-denaturation and aggregation of quinoa (Chenopodium quinoa) globulins as affected by the pH value.

    Science.gov (United States)

    Mäkinen, Outi E; Zannini, Emanuele; Koehler, Peter; Arendt, Elke K

    2016-04-01

    The influence of heating (100 °C; 0-15 min) on the relative molecular mass, protein unfolding and secondary structure of quinoa globulins was studied at pH 6.5 (low solubility), 8.5 and 10.5 (high solubility). The patterns of denaturation and aggregation varied with pH. Heating triggered the disruption of the disulfide bonds connecting the acidic and basic chains of the chenopodin subunits at pH 8.5 and 10.5, but not at pH 6.5. Large aggregates unable to enter a 4% SDS-PAGE gel were formed at pH 6.5 and 8.5, which became soluble under reducing conditions. Heating at pH 10.5 lead to a rapid dissociation of the native chenopodin and to the disruption of the subunits, but no SDS-insoluble aggregates were formed. No major changes in secondary structure occurred during a 15 min heating, but an increase in hydrophobicity indicated unfolding of the tertiary structure in all samples.

  12. Determination of Trace Elements,Tannin,Flavonoids and pH Value in Marigold%万寿菊中微量元素、单宁、黄酮含量及 pH 值的测定

    Institute of Scientific and Technical Information of China (English)

    刘云华; 韩辉; 王吉秀; 张仙; 黄渝翔; 殷彩霞

    2014-01-01

    The contents of trace elements,tannin,flavonoids and pH value of petals,seeds,aerial part remo-ving the petals and seeds,and the underground part of marigold were determined and the correlation were ana-lyzed.The results showed:the content of Zn in different parts was the highest;the content of each trace element in seeds was the highest;the contents of tannin and flavonoids in petals were the highest,but its pH value were the lowest;the content correlations of As with Pb,flavonoids with As or Pb were significant.%分别对万寿菊花瓣、种子、地上(除去花瓣和种子)及地下部分的微量元素、单宁、黄酮含量及 pH 值进行了测定,并分析了其相关性。结果显示:种子中各微量元素的含量均较高;不同部位中微量元素 Zn 的含量最高;花瓣中的单宁含量和黄酮含量最高,但 pH 值最小;As 与 Pb 显著相关,As、Pb 与黄酮含量显著相关。

  13. X-ray absorption near-edge structure study on the configuration of Cu 2+ /histidine complexes at different pH values

    Science.gov (United States)

    Mei-Juan, Yu; Yu, Wang; Wei, Xu

    2016-04-01

    The local configurations around metal ions in metalloproteins are of great significance for understanding their biological functions. Cu2+/histidine (His) is a typical complex existing in many metalloproteins and plays an important role in lots of physiological functions. The three-dimensional (3D) structural configurations of Cu2+/His complexes at different pH values (2.5, 6.5, and 8.5) are quantitatively determined by x-ray absorption near-edge structure (XANES). Generally Cu2+/His complex keeps an octahedral configuration consisting of oxygen atoms from water molecules and oxygen or nitrogen atoms from histidine molecules coordinated around Cu2+. It is proved in this work that the oxygen atoms from water molecules, when increasing the pH value from acid to basic value, are gradually substituted by the Ocarboxyl, Nam, and Nim from hisitidine molecules. Furthermore, the symmetries of Cu2+/His complexes at pH 6.5 and pH 8.5 are found to be lower than at pH 2.5. Project supported by the National Natural Science Foundation of China (Grant No. 11205186).

  14. Stability of the calcium hydroxyzincate protective layer developed on galvanized reinforcements after a further increase of the pH value

    Directory of Open Access Journals (Sweden)

    Andrade, C.

    1986-12-01

    Full Text Available In previous works on galvanized reinforcements in contact with Ca- containing highly alkaline media, the authors have reported the existence of a threshold pH of 13,3 ± 0,1, below which the Zn in contact with such a medium is passivated by formation of a continuous layer of calcium hydroxyzincate, but at pH values above this it corrodes continuously until it totally disappears. The investigation on the stability of the calcium hydroxyzincate layer after an increase of the pH to very high alkaline values, is the aim of the present paper. It has been establised that if the calcium hydroxyzincate is perfectly developed, a later increase of the pH does not affect the stability.

    En trabajos anteriores que estudian el comportamiento de armaduras galvanizadas en contacto con medios muy alcalinos que contienen calcio, los autores han señalado la existencia de un umbral de pH = 13,3 ±0,1 por debajo del cual el Zn en contacto con tales medios se pasiva por formación de una capa continua de hidroxizincato calcico, mientras que para valores de pH superiores se corroe continuamente hasta su total desaparición. Establecer la estabilidad del recubrimiento protector de hidroxizincato calcico a un aumento de pH a valores muy alcalinos posterior a su formación, es el objetivo del presente artículo. Como resultado de las investigaciones realizadas ha podido concluirse que si el recubrimiento de hidroxizincato cálcico se ha desarrollado perfectamente, un posterior incremento del pH del medio no afecta su estabilidad.

  15. Using extreme value theory approaches to forecast the probability of outbreak of highly pathogenic influenza in Zhejiang, China.

    Directory of Open Access Journals (Sweden)

    Jiangpeng Chen

    Full Text Available Influenza is a contagious disease with high transmissibility to spread around the world with considerable morbidity and mortality and presents an enormous burden on worldwide public health. Few mathematical models can be used because influenza incidence data are generally not normally distributed. We developed a mathematical model using Extreme Value Theory (EVT to forecast the probability of outbreak of highly pathogenic influenza.The incidence data of highly pathogenic influenza in Zhejiang province from April 2009 to November 2013 were retrieved from the website of Health and Family Planning Commission of Zhejiang Province. MATLAB "VIEM" toolbox was used to analyze data and modelling. In the present work, we used the Peak Over Threshold (POT model, assuming the frequency as a Poisson process and the intensity to be Pareto distributed, to characterize the temporal variability of the long-term extreme incidence of highly pathogenic influenza in Zhejiang, China.The skewness and kurtosis of the incidence of highly pathogenic influenza in Zhejiang between April 2009 and November 2013 were 4.49 and 21.12, which indicated a "fat tail" distribution. A QQ plot and a mean excess plot were used to further validate the features of the distribution. After determining the threshold, we modeled the extremes and estimated the shape parameter and scale parameter by the maximum likelihood method. The results showed that months in which the incidence of highly pathogenic influenza is about 4462/2286/1311/487 are predicted to occur once every five/three/two/one year, respectively.Despite the simplicity, the present study successfully offers the sound modeling strategy and a methodological avenue to implement forecasting of an epidemic in the midst of its course.

  16. Determination and Visualization of pH Values in Anaerobic Digestion of Water Hyacinth and Rice Straw Mixtures Using Hyperspectral Imaging with Wavelet Transform Denoising and Variable Selection

    Directory of Open Access Journals (Sweden)

    Chu Zhang

    2016-02-01

    Full Text Available Biomass energy represents a huge supplement for meeting current energy demands. A hyperspectral imaging system covering the spectral range of 874–1734 nm was used to determine the pH value of anaerobic digestion liquid produced by water hyacinth and rice straw mixtures used for methane production. Wavelet transform (WT was used to reduce noises of the spectral data. Successive projections algorithm (SPA, random frog (RF and variable importance in projection (VIP were used to select 8, 15 and 20 optimal wavelengths for the pH value prediction, respectively. Partial least squares (PLS and a back propagation neural network (BPNN were used to build the calibration models on the full spectra and the optimal wavelengths. As a result, BPNN models performed better than the corresponding PLS models, and SPA-BPNN model gave the best performance with a correlation coefficient of prediction (rp of 0.911 and root mean square error of prediction (RMSEP of 0.0516. The results indicated the feasibility of using hyperspectral imaging to determine pH values during anaerobic digestion. Furthermore, a distribution map of the pH values was achieved by applying the SPA-BPNN model. The results in this study would help to develop an on-line monitoring system for biomass energy producing process by hyperspectral imaging.

  17. Extreme-value statistics from Lagrangian convex hull analysis I. Validation for homogeneous turbulent Boussinesq convection and MHD convection

    CERN Document Server

    Pratt, J; Müller, W -C; Chapman, S C; Watkins, N W

    2016-01-01

    We investigate the utility of the convex hull to analyze physical questions related to the dispersion of a group of much more than four Lagrangian tracer particles in a turbulent flow. Validation of standard dispersion behaviors is a necessary preliminary step for use of the convex hull to describe turbulent flows. In simulations of statistically homogeneous and stationary Navier-Stokes turbulence, neutral fluid Boussinesq convection, and MHD Boussinesq convection we show that the convex hull can be used to reasonably capture the dispersive behavior of a large group of tracer particles. We validate dispersion results produced with convex hull analysis against scalings for Lagrangian particle pair dispersion. In addition to this basic validation study, we show that convex hull analysis provides information that particle pair dispersion does not, in the form of a extreme value statistics, surface area, and volume for a cluster of particles. We use the convex hull surface area and volume to examine the degree of...

  18. Study on Effects of Bait pH Values on Termite Feeding%诱饵pH值对白蚁取食影响的研究

    Institute of Scientific and Technical Information of China (English)

    孙立祥; 胡敏; 胡胜元; 潘长春

    2014-01-01

    Phagostimulants for killing termites are baits prepared with auxiliary agents including toxicants and preservatives. The pH values of the additives are different and affect the bait pH value. In the study Macrotermes barneyi were fed with baits prepared with water solutions having different pH values,and the ratio of water solution to base material was 3:10 with the control bait prepared with water solution having pH value 7. The results showed that bait pH values affected Macrotermes barneyi feeding on baits. Consumption by Macrotermes barneyi of baits prepared with water solutions having pH value ≤4 and ≥10 was significantly lower than that of the control bait. The water solution pH value range for preparation of baits suitable to be fed on by Macrotermes barneyi was 5~9.%灭杀白蚁诱剂是由饵料中添加毒剂和防腐剂等辅剂配制而成,这些添加成份酸碱度各不相同,并且影响饵料pH值。本研究用不同pH值水溶液配制饵料饲喂黄翅大白蚁,水溶液与基料比为3颐10,用pH值为7水溶液配制饵料作对照。试验结果表明,饵料基pH值影响黄翅大白蚁对饵料取食,溶液pH值臆4和逸10时所配制的饵料,黄翅大白蚁取食饵料量显著少于对照,适宜黄翅大白蚁取食的饵料配制溶液pH区间为5耀9。

  19. Influence of pH value on microstructure and thermal stability of Ni-P electroless coating prepared in acidic condition

    Institute of Scientific and Technical Information of China (English)

    Xiao Wei Zhou; Hui Ming Jin; Lin Nan Zhang

    2009-01-01

    Three kinds of Ni-P electroless coatings were prepared in nickel sulphate solution at different pH values of 4.5, 5.5 and 6.5 with the purpose of ascertaining the influence of pH value on microstructure, internal stress statue and thermal stability of the coatings. Laser curvature (LC) method was used to measure the residual stress level in the coatings. Scanning electronic microscopy (SEM) and transmission electronic microscopy with energy dispersive spectrum (TEM/EDS) were used to examine the surface morphology and internal phase structure of the coatings, respectively. Differential scanning calorimeter (DSC) was used to analyze the phase transformation and thermal stability of the coatings at high temperature. Results showed the Ni-P coating prepared at pH 5.5 with nanocrystal mixed in amorphous structure had the worst thermal stability. The relatively higher stability of Ni-P coatings prepared at pH 4.5 and 6.5 was ascribed to the lower tensile stress level and much finer grain size, respectively. Besides, inverse Hall-Petch effect of annealing strengthening might also contribute to the integrity of Ni-P coating prepared at pH 6.5.

  20. Changes in composition and enamel demineralization inhibition activities of gallic acid at different pH values

    NARCIS (Netherlands)

    Zhang, J.; Huang, X.; Huang, S.; Deng, M.; Xie, X.; Liu, M.; Liu, H.; Zhou, X.; Li, J.; ten Cate, J.M.

    2015-01-01

    Background. Gallic acid (GA) has been shown to inhibit demineralization and enhance remineralization of enamel; however, GA solution is highly acidic. This study was to investigate the stability of GA solutions at various pH and to examine the resultant effects on enamel demineralization. Methods. T

  1. Early effects of oral administration of lafutidine with mosapride compared with lafutidine alone on intragastric pH values

    Directory of Open Access Journals (Sweden)

    Koide Tomoko

    2009-07-01

    Full Text Available Abstract Background The ideal medication for treatment of acid related diseases should have a rapid onset of action to promote hemostasis and resolution of symptoms. The aim of our study was to investigate the inhibitory effects on gastric acid secretion after a single oral administrations of lafutidine, is a newly synthesized H2-receptor antagonist, with mosapride 5 mg or lafutidine alone. Methods Ten Helicobacter pylori negative male subjects participated in this randomized, two-way crossover study. Intragastric pH was monitored continuously for 4 hours after a single oral administration of lafutidine 10 mg or lafutidine 10 mg with mosapride 5 mg (the lafutidine being administrated one hour after the mosapride. Each administration was separated by a 7-day washout period. Results The average pH during the 4-hour period after administration of lafutidine 10 mg with mosapride 5 mg was higher than after lafutidine 10 mg alone (median: 5.25 versus 4.58, respectively; p = 0.0318. During the 3–4 hour study period, lafutidine 10 mg with mosapride 5 mg provided a higher pH, compared to lafutidine 10 mg alone (median: 7.28 versus 6.42; p = 0.0208. Conclusion In H. pylori negative healthy male subjects, an oral dose of lafutidine 10 mg with mosapride 5 mg more rapidly increased intragastric pH than lafutidine 10 mg alone.

  2. Stochastic Modeling of Long-Term and Extreme Value Estimation of Wind and Sea Conditions for Probabilistic Reliability Assessments of Wave Energy Devices

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kofoed, Jens Peter; Sørensen, John Dalsgaard

    2014-01-01

    Wave energy power plants are expected to become one of the major future contribution to the sustainable electricity production. Optimal design of wave energy power plants is associated with modeling of physical, statistical, measurement and model uncertainties. This paper presents stochastic models....... The stochastic model for extreme value estimation covers annual extreme value distributions and the statistical uncertainty due to limited amount of available data. Furthermore, updating based on new available data is explained based on a Bayesian approach. The statistical uncertainties are estimated based...... on the Maximum-Likelihood method, and the extreme value estimation uses the peaks-over-threshold (POT) method. Two generic examples of reliability assessments for failure due to fatigue and extreme...

  3. The influence of pH value and composition on the microstructure, magnetic properties of Co-Fe-Al Heusler nanoparticles

    Science.gov (United States)

    Yang, F. J.; Min, J. J.; Kang, Z. W.; Tu, S. Y.; Chen, H. B.; Liu, D. G.; Li, W. J.; Chen, X. Q.; Yang, C. P.

    2017-02-01

    Co-Fe-Al nanoparticles were synthesized by using a simple solution reduction method. The effects of pH value and atomic composition on the morphology, microstructure and magnetic properties of the prepared Co-Fe-Al nanoparticles were investigated. It was found that pure Co-Fe-Al phase with small particle size can be obtained at pH = 7.0 which have high saturation magnetization and low coercivity. Furthermore, the defects will increase with the increasing of Co composition in Co-Fe-Al nanoparticles which induce the deterioration of the B2 ordering, the abrupt decrease of magnetic moment and the abrupt increase of coercivity.

  4. Extreme events in total ozone over Arosa – Part 2: Fingerprints of atmospheric dynamics and chemistry and effects on mean values and long-term changes

    Directory of Open Access Journals (Sweden)

    H. E. Rieder

    2010-05-01

    Full Text Available In this study the frequency of days with extreme low (termed ELOs and extreme high (termed EHOs total ozone values and their influence on mean values and trends are analyzed for the world's longest total ozone record (Arosa, Switzerland. The results show (a an increase in ELOs and (b a decrease in EHOs during the last decades and (c that the overall trend during the 1970s and 1980s in total ozone is strongly dominated by changes in these extreme events. After removing the extremes, the time series shows a strongly reduced trend (reduction by a factor of 2.5 for trend in annual mean. Excursions in the frequency of extreme events reveal "fingerprints" of dynamical factors such as ENSO or NAO, and chemical factors, such as cold Arctic vortex ozone losses, as well as major volcanic eruptions of the 20th century (Gunung Agung, El Chichón, Mt. Pinatubo. Furthermore, atmospheric loading of ozone depleting substances leads to a continuous modification of column ozone in the Northern Hemisphere also with respect to extreme values (partly again in connection with polar vortex contributions. Application of extreme value theory allows the identification of many more such "fingerprints" than conventional time series analysis of annual and seasonal mean values. The analysis shows in particular the strong influence of dynamics, revealing that even moderate ENSO and NAO events have a discernible effect on total ozone. Overall the approach to extremal modelling provides new information on time series properties, variability, trends and the influence of dynamics and chemistry, complementing earlier analyses focusing only on monthly (or annual mean values.

  5. Extreme events in total ozone over Arosa – Part 2: Fingerprints of atmospheric dynamics and chemistry and effects on mean values and long-term changes

    Directory of Open Access Journals (Sweden)

    H. E. Rieder

    2010-10-01

    Full Text Available In this study the frequency of days with extreme low (termed ELOs and extreme high (termed EHOs total ozone values and their influence on mean values and trends are analyzed for the world's longest total ozone record (Arosa, Switzerland. The results show (i an increase in ELOs and (ii a decrease in EHOs during the last decades and (iii that the overall trend during the 1970s and 1980s in total ozone is strongly dominated by changes in these extreme events. After removing the extremes, the time series shows a strongly reduced trend (reduction by a factor of 2.5 for trend in annual mean. Excursions in the frequency of extreme events reveal "fingerprints" of dynamical factors such as ENSO or NAO, and chemical factors, such as cold Arctic vortex ozone losses, as well as major volcanic eruptions of the 20th century (Gunung Agung, El Chichón, Mt. Pinatubo. Furthermore, atmospheric loading of ozone depleting substances leads to a continuous modification of column ozone in the Northern Hemisphere also with respect to extreme values (partly again in connection with polar vortex contributions. Application of extreme value theory allows the identification of many more such "fingerprints" than conventional time series analysis of annual and seasonal mean values. The analysis shows in particular the strong influence of dynamics, revealing that even moderate ENSO and NAO events have a discernible effect on total ozone. Overall the approach to extremal modelling provides new information on time series properties, variability, trends and the influence of dynamics and chemistry, complementing earlier analyses focusing only on monthly (or annual mean values.

  6. 我国举办极限运动赛事的价值分析%Value of Extreme Sports Events Hosted in China

    Institute of Scientific and Technical Information of China (English)

    郑瑾; 刘美凤

    2012-01-01

    On the basis of elaborating on extreme sports and competitions,the paper discusses the sports value,culture value as well as economic value of extreme sports events and puts forward some reasonable suggestions on the development of extreme sports events in China.The extreme sports can be popularized and promoted among teenagers through hosting the extreme sports events.Small and medium-sized cities should bid actively for hosting extreme sports events.Necessary tangible supports and guarantee should be available to speed up the construction of the theme park of extreme sports.%在对极限运动及赛事阐述的基础上,对极限运动赛事的体育价值、文化价值、经济价值进行探讨,并对我国极限运动赛事的发展提出合理性建议:通过极限运动赛事,在青少年中推广和普及极限运动;中小城市应积极申办极限运动赛事;加快极限运动主题公园建设,为赛事举办提供必要的硬件支持与保障。

  7. Investigation of the adsorption of anionic surfactants at different pH values by means of active carbon and the kinetics of adsorption

    Directory of Open Access Journals (Sweden)

    SIBEL ZOR

    2004-01-01

    Full Text Available In this study, the effect of pH on the removal of anionic surfactants, such as linear alkyl benzene sulfonate (LABS and dodecyl benzene sulfonate (DBS by means of adsorption by activated carbon was investigated. For this purpose activated carbon was used as adsorbent. Anionic surfactant solutions with initial pH values of 3, 6, 8 and 12 were used. The adsorption isotherms for the adsorption of anionic surfactants by active carbon at different pH were determined. These adsorption isotherms were seen to be consistent with Freundlich’s adsorption isotherm. k and n constants were determined from Freundlich’s linear equation. Adsorption rate constants were determined from the obtained kinetic curves which were suitable for the first order of rate kinetics.

  8. Volcanic hazard assessment for the Canary Islands (Spain) using extreme value theory, and the recent volcanic eruption of El Hierro

    Science.gov (United States)

    Sobradelo, R.; Martí, J.; Mendoza-Rosas, A. T.; Gómez, G.

    2012-04-01

    The Canary Islands are an active volcanic region densely populated and visited by several millions of tourists every year. Nearly twenty eruptions have been reported through written chronicles in the last 600 years, suggesting that the probability of a new eruption in the near future is far from zero. This shows the importance of assessing and monitoring the volcanic hazard of the region in order to reduce and manage its potential volcanic risk, and ultimately contribute to the design of appropriate preparedness plans. Hence, the probabilistic analysis of the volcanic eruption time series for the Canary Islands is an essential step for the assessment of volcanic hazard and risk in the area. Such a series describes complex processes involving different types of eruptions over different time scales. Here we propose a statistical method for calculating the probabilities of future eruptions which is most appropriate given the nature of the documented historical eruptive data. We first characterise the eruptions by their magnitudes, and then carry out a preliminary analysis of the data to establish the requirements for the statistical method. Past studies in eruptive time series used conventional statistics and treated the series as an homogeneous process. In this paper, we will use a method that accounts for the time-dependence of the series and includes rare or extreme events, in the form of few data of large eruptions, since these data require special methods of analysis. Hence, we will use a statistical method from extreme value theory. In particular, we will apply a non-homogeneous Poisson process to the historical eruptive data of the Canary Islands to estimate the probability of having at least one volcanic event of a magnitude greater than one in the upcoming years. Shortly after the publication of this method an eruption in the island of El Hierro took place for the first time in historical times, supporting our method and contributing towards the validation of

  9. Bicelle-based liquid crystals for NMR-measurement of dipolar couplings at acidic and basic pH values

    Energy Technology Data Exchange (ETDEWEB)

    Ottiger, Marcel; Bax, Ad [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Laboratory of Chemical Physics (United States)

    1999-02-15

    It is demonstrated that mixtures of ditetradecyl- phosphatidylcholine or didodecyl-phoshatidylcholine and dihexyl- phosphatidylcholine in water form lyotropic liquid crystalline phases under similar conditions as previously reported for bicelles consisting of dimyristoyl-phosphatidylcholine (DMPC) and dihexanoyl- phosphatidylcholine (DHPC). The carboxy-ester bonds present in DMPC and DHPC are replaced by ether linkages in their alkyl analogs, which prevents acid- or base-catalyzed hydrolysis of these compounds. 15N-1H dipolar couplings measured for ubiquitin over the 2.3-10.4pH range indicate that this protein retains a backbone conformation which is very similar to its structure at pH 6.5 over this entire range.

  10. Effect of various pH values, ionic strength, and temperature on papain hydrolysis of salivary film.

    Science.gov (United States)

    Yao, Jiang-Wu; Xiao, Yin; Lin, Feng

    2012-04-01

    Stimulated human whole saliva (WS) was used to study the dynamics of papain hydrolysis at defined pH, ionic strength, and temperature with the view of reducing an acquired pellicle. A quartz crystal microbalance with dissipation (QCM-D) was used to monitor the changes in frequency caused by enzyme hydrolysis of WS films, and the hydrolytic parameters were calculated using an empirical model. The morphological and conformational changes of the salivary films before and after enzymatic hydrolysis were characterized by atomic force microscopy (AFM) imaging and grazing-angle Fourier transform infrared (GA-FTIR ) spectra, respectively. The characteristics of papain hydrolysis of WS films were pH-, ionic strength-, and temperature-dependent. The WS films were partially removed by the action of papain, resulting in thinner and smoother surfaces. The infrared data suggested that hydrolysis-induced deformation did not occur on the remnants of salivary films. The processes of papain hydrolysis of WS films can be controlled by properly regulating pH, ionic strength, and temperature.

  11. 酸碱度值对土体液、塑限的影响%EFFECTS OF PH VALUE ON LIQUID LIMIT AND PLASTIC LIMIT OF SOIL

    Institute of Scientific and Technical Information of China (English)

    师林; 朱大勇; 陈龙飞

    2011-01-01

    By using the method of soaking in laboratory,the change laws between the liquid limit,plastic limit and plasticity index of the polluted soil and the pH value were studied.The values of the liquid limit and plastic limit of the soil samples were measured before and after soaking in the hydrochloric acid and sodium hydroxide solution with respective pH value.Then,the change laws indicate that,with the pH value increasing,the liquid limit and the plasticity index increase while the plastic limit presents that both ends are big and the middle is small;when fixing the pH value,the liquid limit is increasing proportional to the time of soaking,while the plastic limit is diminishing.Finally,the reasons causing these change laws were analyzed.%采用室内浸泡方法,研究污染土的液、塑限以及塑性指数随酸碱度值的变化规律。用不同酸碱度值的盐酸和氢氧化钠溶液浸泡土样,测定浸泡前、后土样的液、塑限值,总结其变化规律。试验表明:随着酸碱度值的增大,液限和塑性指数逐渐增大而塑限呈现两端大中间小;在酸碱度值一定的情况下,随着浸泡时间的增长,土样有液限值逐渐减小、塑限值逐渐增大的趋势。最后,对上述变化的原因进行分析。

  12. Water-, pH- and temperature relations of germination for the extreme xerophiles Xeromyces bisporus (FRR 0025), Aspergillus penicillioides (JH06THJ), and Eurtotium halophilicum (FRR 2471)

    OpenAIRE

    Stevenson, Andrew; Hamill, Philip G.; Dijksterhuis, Jan; Hallsworth, John

    2016-01-01

    Summary Water activity, temperature and pH are determinants for biotic activity of cellular systems, biosphere function and, indeed, for all life processes. This study was carried out at high concentrations of glycerol, which concurrently reduces water activity and acts as a stress protectant, to characterize the biophysical capabilities of the most extremely xerophilic organisms known. These were the fungal xerophiles: Xeromyces bisporus (FRR 0025), Aspergillus penicillioides (JH06THJ) and E...

  13. The effects of extremes of pH on the growth and transcriptomic profiles of three haloarchaea [v1; ref status: indexed, http://f1000r.es/3y1

    Directory of Open Access Journals (Sweden)

    Aida Moran-Reyna

    2014-07-01

    Full Text Available The halophilic archaea (haloarchaea live in saline environments which are found across the globe.  In addition to salinity, these niches can be quite dynamic and experience extreme conditions such as low oxygen content, radiation (gamma and UV, pH and temperature.  However, of all the naturally occurring stresses faced by the haloarchaea, only one, pH, has not been previously reported on. Therefore, we endeavored to determine the responses of the transcriptomes of three haloarchaea (Hla, Hvo, and NRC-1 to growth under acidic and alkaline pH. Our observations showed that the transcriptomes of Hvo and NRC-1 respond in a similar manner to each other as well as other prokaryotes when grown in an acidic environment, while the pattern for Hla was dissimilar. For alkaline stress, all three haloarchaea responded in a manner similar to well-studied archaea and bacteria and had four-times more significantly regulated transcripts in common, compared to acidic growth. Additionally, we performed an analysis on the changes in the transcriptomes of the three haloarchaea when shifting from one pH extreme to the other. The results showed that the transcriptomes of all three haloarchaea respond more similarly when moving from alkaline to acidic conditions compared to moving from an acidic to alkaline environment. Interestingly, our studies also showed that individual genes of multiple paralogous gene families (tbp, tfb, orc/cdc6, etc. found in the haloarchaea were regulated under specific stresses thereby providing evidence that they modulate the response to various environmental stresses. The studies described here are the first to catalog the changes in the haloarchaeal transcriptomes under growth in extreme pH and help us understand how life is able to thrive under all conditions present on Earth and, if present, on extraterrestrial bodies as well.

  14. The effects of extremes of pH on the growth and transcriptomic profiles of three haloarchaea [v2; ref status: indexed, http://f1000r.es/48e

    Directory of Open Access Journals (Sweden)

    Aida Moran-Reyna

    2014-08-01

    Full Text Available The halophilic archaea (haloarchaea live in saline environments, which are found across the globe.  In addition to salinity, these niches can be quite dynamic and experience extreme conditions such as low oxygen content, radiation (gamma and UV, pH and temperature.  However, of all the naturally occurring stresses faced by the haloarchaea, only one, pH, has not been previously investigated in regard to the changes induced in the transcriptome. Therefore, we endeavored to determine the responses in three haloarchaea: Halorubrum lacusprofundi (Hla, Haloferax volcanii (Hvo, and Halobacterium sp. NRC-1 (NRC-1 to growth under acidic and alkaline pH. Our observations showed that the transcriptomes of Hvo and NRC-1 regulated stress, motility, and ABC transporters in a similar manner, which is in line with previous reports from other prokaryotes when grown in an acidic environment.  However, the pattern for Hla was more species specific. For alkaline stress, all three haloarchaea responded in a manner similar to well-studied archaea and bacteria showing the haloarchaeal response was general to prokaryotes. Additionally, we performed an analysis on the changes in the transcriptomes of the three haloarchaea when shifting from one pH extreme to the other. The results showed that the transcriptomes of all three haloarchaea respond more similarly when moving from alkaline to acidic conditions compared to a shift in the opposite direction. Interestingly, our studies also showed that individual genes of multiple paralogous gene families (tbp, tfb, orc/cdc6, etc. found in the haloarchaea were regulated under specific stresses thereby providing evidence that they modulate the response to various environmental stresses. The studies described here are the first to catalog the changes in the haloarchaeal transcriptomes under growth in extreme pH and help us understand how life is able to thrive under all conditions present on Earth and, if present, on

  15. Review for Calculation and Application of pH Value%关于pH值的计算及应用专题复习

    Institute of Scientific and Technical Information of China (English)

    郭进利

    2011-01-01

    pH value of liquor is widely applied into chemistry experiments. The calculation ot pH value is of more types and difficulties and students should pay more attention to the correct understanding of concepts and the systematical grasp of knowledge in learn%溶液的pH值在化学实验中有广泛的应用。有关pH值的计算类型多,难度大,在学习过程中要注意对概念的准确理解和知识的系统性掌握。本文对pH值的计算进行了较全面的总结。

  16. A model to explain high values of pH in an alkali sodic soil Modelo para explicar valores elevados de pH em um solo sódico alcalino

    Directory of Open Access Journals (Sweden)

    José Guerrero-Alves

    2002-12-01

    Full Text Available For alkali sodic soils (pH>8.5, the "hydrolysis of exchangeable sodium" has been used as a possible explanation for the alkalinity production and rise in pH of these soils. As an alternative to this hypothesis, a model was developed to simulate and to explain that the alkalinity production and rise in pH is possible in a soil that accumulates alkaline sodium salts and CaCO3. Several simulations were performed by using different combinations of CO2 partial pressures (P, presence or absence of MgCO3, along with experimental values of exchangeable sodium percentage (ESP and ion concentrations in saturation extracts from an alkali sodic soil (named Pantanal. A hypothetical system with similar conditions to the Pantanal soil but with a Gapon selectivity coefficient (KG of 0.01475 (mmol L-1-1/2 was also considered. Good agreement was obtained between experimental and predicted values for pH and ion concentrations in the soil solution when the model (without MgCO3 was applied to the Pantanal soil. However, KG values calculated for the Pantanal soil were generally higher than 0.01475 (mmol L-1-1/2. Moreover, high pH values and elevated ionic strength were obtained when a KG of 0.01475 (mmol L-1-1/2 was used at high ESP (similar to those found in the Pantanal soil. KG values obtained for the Pantanal soil and the results obtained in the simulation of the hypothetical system are suggesting that a value higher than 0.01475 (mmol L-1-1/2 should be used to adequately simulate the behavior of the Pantanal soil at low ionic strength and high ESP values.Em solos alcalino sódicos (pH>8,5, a "hidrólise de sódio trocável" tem sido usada como uma possível explicação para a produção de álcali e elevação do pH nestes solos. Como uma alternativa a essa hipótese, um modelo foi desenvolvido para simular e explicar que a produção de álcali e elevação do pH é possível num solo que acumula sais alcalinos de sódio e CaCO3. Várias simulações foram

  17. Baseline climatology of extremely high vertical wind shears' values over Europe based on ERA-Interim reanalysis

    Science.gov (United States)

    Palarz, Angelika; Celiński-Mysław, Daniel

    2017-04-01

    The dominant role in the development of deep convection is played by kinematic and thermodynamic conditions, as well as atmospheric circulation, land cover and local relief. Severe thunderstorms are considerably more likely to form in environments with large values of convective available potential energy (CAPE) and significant magnitude of vertical wind shears (VWSs). According to the most recent research, the tropospheric wind shears have an important influence on intensity, longevity and organisation of the primary convective systems - bow echoes, squall lines and supercell thunderstorms. This study, in turn, examines the role of wind structure in controlling the spatial and temporal variability of VWSs over Europe. Considering the importance of the kinematic conditions for the convective systems formation, research is limited exclusively to 0-1 km, 0-3 km and 0-6 km wind shears. In order to compute the VWS' values, the data derived from ERA-Interim reanalysis for the period 1981-2015 was applied. It consisted of U and V wind components with 12-hourly sampling and horizontal resolution of 0.75×0.75°. The VWS' values were calculated as wind difference between two levels - this entails that the hodograph's shape was not considered (e.g. Clark 2013, Pucik et. al 2015). We have analysed both VWS' mean values (MN) and frequency of VWSs exceeding assumed thresholds (FQ). Taking into account previous studies (e.g. Rasmussen & Blanchard 1998, Schneider et al. 2006, Schaumann & Przybylinski 2012), the thresholds for extremely high values of vertical wind shears were set at 10 m/s for 0-1 km shear, 15 m/s for 0-3 km shear and 18 m/s for 0-6 km shear. Both MN and FQ values were characterised by strong temporal variability, as well as significant spatial differentiation over the research area. A clear diurnal cycle was identified in the case of 0-1 km shear, while seasonal variability was typical for 0-3 km and 0-6 km shears. Regardless of the season, 0-1 km shear reached

  18. pH 值对原代大鼠肝细胞冻存效果的影响%Effect of pH Value for the Cryopreservation of Primary Rat Hepatocytes

    Institute of Scientific and Technical Information of China (English)

    付建柱; 张立军; 于则利

    2012-01-01

    To evaluate the effect of PH value for the cryopreservation of primary hepatocytes in different solutions. Methods Primary rat hepatocytes were cryopreserved with UW solution and RPMI 1640 solution containing 20% FBS with 12% DMSO. PH value of each solution was adjusted to7.1t 7.4, 7.7 respectively. After thawing the cryopreserved hepatocytes after 7, 14, 28 days, cell viability, MTT and Levels of released LDH were analyzed for each group. Results After 7, 14 and 28 days, hepatocytes cryopreserved in pH 7.4 and pH 7.7 were significantly better in all three terms than pH 7.1. Conclusion Alkalescent Medium environment might be more suitable environment for cryopreservation of rat hepatocytes.%目的 研究不同pH值的条件下原代大鼠肝细胞冻存的效果.方法 将大鼠肝细胞保存在含有20% FSB和12%DMSO的UW液和RPMI 1640液中,并把两种保存液的pH值调节成7.1、7.4、7.7.于冻存7、14、28天后进行复苏,使用存活率、MTT、LDH漏出浓度3项指标进行对比分析.结果 7天时,pH值7.4组的各项指标明显优于其他两组,14天和28天时,pH值7.7组与pH值7.4组均明显优于pH值7.1组.结论 pH值7.4和pH值7.7的保存效果优于pH值7.1,且随着时间的延长,差距有扩大的趋势,说明中性或略偏碱性环境更利于肝细胞的长期保存.

  19. Effects of gaseous ammonia on intracellular pH values in leaves of C 3- and C 4-plants

    Science.gov (United States)

    Yin, Zu-Hua; Kaiser, Werner; Heber, Ulrich; Raven, John A.

    Responses of cytosolic and vacuolar pH to different concentrations (1.3-5.4 μmol NH 3 mol -1 gas or 0.940-3.825 mg NH 3 m -3 gas) of gaseous NH 3 were studied in experiments of 3 h duration by recording changes in fluorescence of pyranine and esculin in leaves of C 3 and C 4 plants. After a lag phase of 0.5-4 min, the uptake of NH 3 at 50-200 nmol m -2 leaf area s -1 increased pyranine fluorescence, indicating cytosolic alkalinization in leaves of Pelargonium zonale L. (C 3) and Amaranthus caudatus L. (C 4). A smaller increase in esculin fluorescence induced by NH 3 indicated some vacuolar alkalization in a Spinacia oleracea L. leaf. Photosynthesis and transpiration remained unchanged during exposure of illuminated leaves to NH 3 for up to 30 min (the maximum tested). CO 2 concentrations influenced the extent of cytosolic alkalinization. 500 μmol CO 2 mol -1 gas suppressed the NH 3-induced cytosolic alkalinization relative to that found in 16 μmol CO 2 mol -1 gas. The suppressing effect of CO 2 on NH 3-induced alkalization was larger in illuminated leaves of the C 4Amaranthus than the C 3Pelargonium. These results indicate that the alkaline pH shift caused by solution and protonation of NH 3 in aqueous leaf compartments is affected by assimilation of NH 3.

  20. Effects of initial pH value of the medium on the alcoholic fermentation performance of Saccharomyces cerevisiae cells immobilized on nipa leaf sheath pieces

    Directory of Open Access Journals (Sweden)

    Hoang Duc Toan Le

    2014-12-01

    Full Text Available Immobilized yeast on nipa leaf sheath pieces was applied to ethanol fermentation using the medium with different initial pH values (5.1, 4.5, 4.0, and 3.5. Control samples with the free yeast were also carried out under the same conditions. Low pH value of 4.0 or 3.5 significantly reduced yeast growth and increased the residual sugar level in the fermentation broths for both the immobilized and free cells. In all cases, the ethanol content produced and ethanol formation rate of the immobilized yeast were 13-33% and 35-69%, respectively, higher than those of the free yeast. In addition, the residual sugar content in the immobilized yeast cultures was 2.1-20.5 times lower than that in the free yeast cultures. The yeast immobilized on nipa leaf stem pieces exhibited higher alcoholic fermentation performance than the free yeast in medium with low pH value. This support was potential for further research for application in ethanol industry.

  1. Differentiating calcium oxalate and hydroxyapatite stones in vivo using dual-energy CT and urine supersaturation and pH values.

    Science.gov (United States)

    Liu, Yu; Qu, Mingliang; Carter, Rickey E; Leng, Shuai; Ramirez-Giraldo, Juan Carlos; Jaramillo, Giselle; Krambeck, Amy E; Lieske, John C; Vrtiska, Terri J; McCollough, Cynthia H

    2013-12-01

    Knowledge of urinary stone composition can guide therapeutic intervention for patients with calcium oxalate (CaOx) or hydroxyapatite (HA) stones. In this study, we determined the accuracy of noninvasive differentiation of these two stone types using dual-energy CT (DECT) and urine supersaturation (SS) and pH values. Patients who underwent clinically indicated DECT scanning for stone disease and subsequent surgical intervention were enrolled. Stone composition was determined using infrared spectroscopy. DECT images were processed using custom-developed software that evaluated the ratio of CT numbers between low- and high-energy images. Clinical information, including patient age, gender, and urine pH and supersaturation profile, was obtained from electronic medical records. Simple and multiple logistic regressions were used to determine if the ratio of CT numbers could discriminate CaOx from HA stones alone or in conjunction with urine supersaturation and pH. Urinary stones (CaOx n = 43, HA n = 18) from 61 patients were included in this study. In a univariate model, DECT data, urine SS-HA, and urine pH had an area under the receiver operating characteristic curve of 0.78 (95% confidence interval [CI] 0.66-0.91, P = .016), 0.76 (95% CI 0.61-0.91, P = .003), and 0.60 (95% CI 0.44-0.75, P = .20), respectively, for predicting stone composition. The combination of CT data and the urinary SS-HA had an area under the receiver operating characteristic curve of 0.79 (95% CI 0.66-0.92, P = .007) for correctly differentiating these two stone types. DECT differentiated between CaOx and HA stones similarly to SS-HA, whereas pH was a poor discriminator. The combination of DECT and urine SS or pH data did not improve this performance. Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.

  2. The influence of elevated CO2 on rain water PH value%CO2含量升高对雨水PH值的影响

    Institute of Scientific and Technical Information of China (English)

    孔慧敏; 龙慧艳

    2014-01-01

    正常雨水的PH值约为5.7左右。酸雨是指PH<5.6的降雨。本文利用化学平衡常数根据公式对雨水中的PH值进行了估算,并推导出CO2分压与ph值的关系,从理论上推导出CO2浓度升高会引起水中氢离子浓度的增大,从而最终导致雨水中ph值下降。指出当二氧化碳的浓度达到一定的浓度,人们将面对除温室效应以外的更深远的影响。%Normal rain PH of about 5.7 or so. Acid rain refers to PH < 5.6 of rain. This paper, by using the chemical equilibrium constant according to the formula to estimate, the PH of rain water and CO2 partial pressure and PH value is deduced, the relationship between elevated CO2 concentration is deduced theoretically will cause the increase of hydrogen ion concentration in water, which eventually led to the decrease of the PH in the rain. Pointed out that when the concentration of carbon dioxide reaches a certain concentration, people will face a more profound influence on other than the greenhouse effect.

  3. Comment on Pisarenko et al. "Characterization of the Tail of the Distribution of Earthquake Magnitudes by Combining the GEV and GPD Descriptions of Extreme Value Theory"

    CERN Document Server

    Raschke, Mathias

    2015-01-01

    In this short note, I comment on the research of Pisarenko et al. (2014) regarding the extreme value theory and statistics in case of earthquake magnitudes. The link between the generalized extreme value distribution (GEVD) as an asymptotic model for the block maxima of a random variable and the generalized Pareto distribution (GPD) as a model for the peak over thresholds (POT) of the same random variable is presented more clearly. Pisarenko et al. (2014) have inappropriately neglected that the approximations by GEVD and GPD work only asymptotically in most cases. This applies particularly for the truncated exponential distribution (TED), being a popular distribution model for earthquake magnitudes. I explain why the classical models and methods of the extreme value theory and statistics do not work well for truncated exponential distributions. As a consequence, the classical methods should be used for the estimation of the upper bound magnitude and corresponding parameters. Furthermore, different issues of s...

  4. Observing Effects of Calcium/Magnesium Ions and pH Value on the Self-Assembly of Extracted Swine Tendon Collagen by Atomic Force Microscopy

    Directory of Open Access Journals (Sweden)

    Xuan Song

    2017-01-01

    Full Text Available Self-assembly of extracted collagen from swine trotter tendon under different conditions was firstly observed using atomic force microscopy; then the effects of collagen concentration, pH value, and metal ions to the topography of the collagen assembly were analyzed with the height images and section analysis data. Collagen assembly under 0.1 M, 0.2 M, 0.3 M CaCl2, and MgCl2 solutions in different pH values showed significant differences (P < 0.05 in the topographical properties including height, width, and roughness. With the concentration being increased, the width of collagen decreased significantly (P < 0.05. The width of collagen fibers was first increased significantly (P < 0.05 and then decreased with the increasing of pH. The collagen was assembled with network structure on the mica in solution with Ca2+ ions. However, it had shown uniformed fibrous structure with Mg2+ ions on the new cleaved mica sheet. In addition, the width of collagen fibrous was 31~58 nm in solution with Mg2+ but 21~50 nm in Ca2+ solution. The self-assembly collagen displayed various potential abilities to construct fibers or membrane on mica surfaces with Ca2+ ions and Mg2+ irons. Besides, the result of collagen self-assembly had shown more relations among solution pH value, metal ions, and collagen molecular concentration, which will provide useful information on the control of collagen self-assembly in tissue engineering and food packaging engineering.

  5. Analyzing Ph value, energy and phospholipid metabolism of various cerebral tumors and normal brain tissue with 31P magnetic resonance spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Wei Tan; Guangyao Wu; Junmo Sun

    2006-01-01

    BACKGROUND: 31P magnetic resonance spectroscopy (31P MRS) can be used to non-injuredly and dynamicly detect various metabolites including phosphorus in organis and reflect changes of phospholipid metabolism and energy metabolism in tissue and pH value in cells.OBJECTIVE: To observe changes of pH value, phospholipid metabolism and energy metabolism of various cerebral tumors and normal brain tissue with 31P MRS.DESIGN: Semi-quantitative contrast observation.PARTICIPANTS: A total of 44 patients with cerebral tumor diagnosed with surgery operation were selected from the Department of Magnetic Resonance, Central South Hospital, Wuhan University from September 2004 to June 2006. All the subjects had complete 31P MRS data before steroid and operation. Among them,16 patients had glioma of grade Ⅱ-Ⅲ, 12 spongioblastoma and 16 meningioma. The mean age was (45±6)years. Another 36 subjects without focus on cerebral MRI were regarded as normal group, including 19 males and 18 females, and the mean age was (41±4) years. Included subjects were consent.METHODS: Eclipse1.5T MRS (Philips Company) was used to collect wave spectrum; jMRUI(1.3) was used to analyze experimental data and calculate pH value in voxel and ratios of phosphocreatine (PCr)/inorganic phosphate (Pi), PCr/phosphodiesterase (PDE) and phosphomonoesterase (PME)/β-adenosine triphosphate (β-ATP) of various metabolites. 31P MRS results were compared with t test between tumor patients and normal subjects.MAIN OUTCOME MEASURES: Changes of phospholipid metabolism (PME/PDE), energy metabolism (PCr/ATP) and pH value of various cerebral tumors and normal brain tissues.RESULTS: A total of 44 cases with cerebral tumor and 36 normal subjects were involved in the final analysis. pH value and semi-quantitative measurements of normal brain tissues and various cerebral tumors: ① pH value at top occipital region and temple occipital region of normal brain tissue was 7.04±0.02;PCt/β-ATP was 1.51 ±0.03; PCt/Pi was 2.85

  6. Effects of pH and hydraulic retention time on hydrogen production versus methanogenesis during anaerobic fermentation of organic household solid waste under extreme-thermophilic temperature (70 degrees C).

    Science.gov (United States)

    Liu, Dawei; Zeng, Raymond J; Angelidaki, Irini

    2008-08-15

    Two continuously stirred tank reactors were operated with household solid waste at 70 degrees C, for hydrogen and methane production. The individual effect of hydraulic retention time (HRT as 1, 2, 3, 4, and 6 days) at pH 7 or pH (5, 5.5, 6, 6.5, 7) at 3-day HRT was investigated on the hydrogen production versus methanogenesis. It was found that at pH 7, the maximum hydrogen yield was 107 mL-H(2)/g VS(added) (volatile solid added) but no stable hydrogen production was obtained as after some time methanogenesis was initiated at all tested HRTs. This demonstrated that sludge retention time alone was not enough for washing out the methanogens at pH 7 under extreme-thermophilic conditions. Oppositely, we showed that keeping the pH level at 5.5 was enough to inhibit methane and produce hydrogen stably at 3-day HRT. However, the maximum stable hydrogen yield was low at 21 mL-H(2)/g VS(added).

  7. Effects of pH and hydraulic retention time on hydrogen production versus methanogenesis during anaerobic fermentation of organic household solid waste under extreme-thermophilic temperature (70ºC)

    DEFF Research Database (Denmark)

    Liu, Dawei; Zeng, Raymond Jianxiong; Angelidaki, Irini

    2008-01-01

    Two continuously stirred tank reactors were operated with household solid waste at 70°C, for hydrogen and methane production. The individual effect of hydraulic retention time (HRT as 1, 2, 3, 4, and 6 days) at pH 7 or pH (5, 5.5, 6, 6.5, 7) at 3-day HRT was investigated on the hydrogen production...... versus methanogenesis. It was found that at pH 7, the maximum hydrogen yield was 107 mL-H2/g VSadded (volatile solid added) but no stable hydrogen production was obtained as after some time methanogenesis was initiated at all tested HRTs. This demonstrated that sludge retention time alone was not enough...... for washing out the methanogens at pH 7 under extreme-thermophilic conditions. Oppositely, we showed that keeping the pH level at 5.5 was enough to inhibit methane and produce hydrogen stably at 3-day HRT. However, the maximum stable hydrogen yield was low at 21 mL-H2/g VSadded. Biotechnol. Bioeng. 2008...

  8. 堆叠pH值对Mozzarella干酪熔化特性的影响%Effect of Milling pH Value on Mozzarella Cheese Meltability

    Institute of Scientific and Technical Information of China (English)

    郭媛; 郭慧媛; 王芳; 万长江; 姜鹭; 任发政

    2011-01-01

    研究了堆叠pH值对Mozzarella干酪熔化性的影响.通过考察不同堆叠pH值Mozzarella干酪贮藏1~7周的熔化性、可冻结水含量、pH值4.6可溶性氮含量、Urea-PAGE电泳,利用共聚焦激光扫描电镜、差示热量扫描仪、流变仪,探讨了堆叠pH值与Mozzarella干酪熔化特性的联系.结果表明,低堆叠pH值的Mozzarella干酪样品可冻结水含量低,结合水含量高,随贮藏期延长(21 d以上)蛋白水解片段增多,形成的纤维状结构更加有序,相应的熔化性更好.%The effect of different milling pH value on cheese meltability was studied. Combined with confocal laser scanning spectroscopy, DSC and rheometer techniques, meltability, freezable water content, pH 4. 6-soluble protein and Urea-PAGE were analyzed during 1 ~ 7 weeks storages. Results showed that Mozzarella cheese with a low milling pH value had less freezable water and more binding water. When the storage prolonged (more than 21 d) , protein degradation increased, and better meltability was achieved.

  9. Alternative growth functions for predicting body, carcass, and breast weight in ducks: Lomolino equation and extreme value function.

    Science.gov (United States)

    Faridi, A; Murawska, D; Golian, A; Mottaghitalab, M; Gitoee, A; Lopez, S; France, J

    2014-04-01

    In this study, 2 alternative growth functions, the Lomolino and the extreme value function (EVF), are introduced and their ability to predict body, carcass, and breast weight in ducks evaluated. A comparative study was carried out of these equations with standard growth functions: Gompertz, exponential, Richards, and generalized Michaelis-Menten. Goodness of fit of the functions was evaluated using R(2), mean square error, Akaike information criterion, and Bayesian information criterion, whereas bias factor, accuracy factor, Durbin-Watson statistic, and number of runs of sign were the criteria used for analysis of residuals. Results showed that predictive performance of all functions was acceptable, though the Richards and exponential equations failed to converge in a few cases for both male and female ducks. Based on goodness-of-fit statistics, the Richards, Gompertz, and EVF were the best equations whereas the worst fits to the data were obtained with the exponential. Analysis of residuals indicated that, for the different traits investigated, the least biased and the most accurate equations were the Gompertz, EVF, Richards, and generalized Michaelis-Menten, whereas the exponential was the most biased and least accurate. Based on the Durbin-Watson statistic, all models generally behaved well and only the exponential showed evidence of autocorrelation for all 3 traits investigated. Results showed that with all functions, estimated final weights of males were higher than females for the body, carcass, and breast weight profiles. The alternative functions introduced here have desirable advantages including flexibility and a low number of parameters. However, because this is probably the first study to apply these functions to predict growth patterns in poultry or other animals, further analysis of these new models is suggested.

  10. Investigation on Soil pH Value in Tobacco Field in Zhuxi County%竹溪县烟田土壤酸碱度调查

    Institute of Scientific and Technical Information of China (English)

    杨继龙; 刘阳; 王远林; 王官明; 张良培; 张晓亮; 张凯

    2016-01-01

    Objective] To study the status of soil pH value of tobacco field in Zhuxi city, and to put forward the improving measures.[ Meth-od] The soil pH values of 817 fields belonging to 587 tobacco families of 38 villages in 5 towns were measured.[ Result] The county average soil pH value was 6.30, the maximum value was 8.5, the minimum value was 5.0.The pH values of 579 samples were all lower than 6.5, which accounted for 70.9% and indicated that the most of the tested soil samples were the weak acid.Soil pH values of 736 samples were be-tween 5.0 to 7.0, which was suitable for the tobacco growth, and accounted for more than 90.09%.[Conclusion] The soil pH value of to-bacco fields is mainly weak acidity in Zhuxi County.There is acidification phenomenon in soil at present, but it is not serious.Zhuxi County is still the suitable production area for high-quality flue-cured tobacco by carrying out the sustained increase of organic fertilizer, planting green manure, crop rotation, replacing potassium sulfate by potassium nitrate.%[目的]调查竹溪县烟叶种植田间土壤酸碱度的现状,提出相应的改良措施。[方法]对全县5个乡镇38个行政村583户烟农的817个田块进行检测。[结果]全县土壤pH平均值为6.30,最大值为8.5,最小值为5.0,pH在6.5以下的样本数579个,占比70.9%,整体呈弱酸性。适宜烤烟生长的土壤样本(pH 5.5~7.0)有736个,占比90.09%。[结论]竹溪县烟田土壤以弱酸性(pH 5.5~6.5)为主。当前土壤酸化现象并不严重,通过持续开展增施有机肥、种植绿肥、轮作、硝酸钾替代硫酸钾等改良措施,竹溪县仍为适宜生产优质烤烟的区域。

  11. Effect of weak acid preservatives on growth of bakery product spoilage fungi at different water activities and pH values.

    Science.gov (United States)

    Suhr, K I; Nielsen, P V

    2004-08-15

    Inhibition of spoilage organisms from bakery products by weak acid preservatives in concentrations of 0%, 0.003%, 0.03% and 0.3% (w/v) was investigated experimentally on a substrate media with water activity (a(w)) and pH ranging from sourdough-fermented acidic rye bread to alkaline intermediate moisture sponge cake types (a(w) 0.80-0.95, pH 4.7-7.4). Initially, rye bread conditions (a(w) 0.94-0.97 and pH 4.4-4.8) in combination with calcium propionate were investigated. Results showed that the highest concentration of propionate (0.3%) at all conditions apart from high a(w) (0.97) and high pH (4.8) totally inhibited fungal growth for a 2-week period, with the exception of Penicillium roqueforti, Penicillium commune and Eurotium rubrum. Characteristically for the major spoiler of rye bread, P. roqueforti, all three isolates tested were stimulated by propionate and the stimulation was significantly enhanced at high water activity levels. The effect of propionate on production of secondary metabolites (mycophenolic acid, rugulovasine, echinulin, flavoglaucin) was also studied, and variable or isolate dependent results were found. Subsequently, a screening experiment representing a wider range of bakery products was conducted using calcium propionate, potassium sorbate and sodium benzoate. The obtained data was modelled using survival analysis to determine 'spoilage-free time' for the fungi. At the low a(w) level (0.80) only Eurotium species grew within the test period of 30 days. Higher water activity levels as well as higher pH values decreased spoilage-free times of the fungi. The preservative calcium propionate was less effective than potassium sorbate and sodium benzoate.

  12. Effect of solution pH value changes on fluorescence intensity of magnetic-luminescent Fe3O4@Gd2O3:Eu3+ nanoparticles

    Institute of Scientific and Technical Information of China (English)

    吴拓; 潘桦滟; 陈如标; 罗东; 张宏; 沈晔; 李旸晖; 王乐

    2016-01-01

    In this paper, bifunctional Fe3O4@Gd2O3:Eu3+ core-shell nanoparticles with both magnetic and fluorescent properties were synthesized through a urea homogeneous precipitation (UHP) method. Particular emphasis was placed on investigating the influence of the solution pH value on the photoluminescence of the core-shell nanocomposites. It showed that the samples treated at the solution of pH=3.0 had the highest luminescence due to the enhanced crystallinity and size uniformity of nanoparticles. The Fe3O4@Gd2O3:Eu3+ nanocomposites exhibited an almost spherical shape with a mean diameter of 60 nm, and had strong red emis-sions of Eu3+ at 612 nm as well as good magnetization with the saturation magnetization of 1.29 emu/g. It thus indicated that the core-shell nanocomposites investigated has great potential in biomedical applications.

  13. The effects of work-related values on communication between R and D groups, part 1. Ph.D. Thesis

    Science.gov (United States)

    Douds, C. F.

    1970-01-01

    The research concerned with the liaison, interface, coupling, and technology transfer processes that occur in research and development is reported. Overviews of the functions of communication and coupling in the R and D processes, and the theoretical considerations of coupling, communication, and values are presented along with descriptions of the field research program and the instrumentation.

  14. VARIABILITY OF CONTINUOUSLY MEASURED ARTERIAL PH AND BLOOD-GAS VALUES IN THE NEAR-TERM FETAL LAMB

    NARCIS (Netherlands)

    WOUDSTRA, BR; DEWOLF, BTHM; SMITS, TM; NATHANIELSZ, PW; ZIJLSTRA, WG; AARNOUDSE, JG

    1995-01-01

    In fetal sheep, arterial blood gas values show considerable spontaneous fluctuations. The aim of the present study was to obtain quantitative data on fetal blood gas variability. Accurate assessment of the intraindividual variations can hardly be obtained from intermittent blood samples, but require

  15. 尿液pH值与代谢综合征的相关性研究%Correlation between urinary pH value and metabolic syndrome

    Institute of Scientific and Technical Information of China (English)

    陈颖; 宁光; 杨枝; 黄飞; 王天歌; 李勉; 徐敏; 徐瑜; 毕宇芳; 陆洁莉

    2012-01-01

    Objective To investigate the correlation between urinary pH value and metabolic syndrome in middle-aged and elderly Chinese people. Methods Two thousand three hundred and twenty-two subjects aged 40 years or older from Jiading community, Shanghai, were enrolled in this study. Questionnaire interview, physical examination, and blood biochemical tests including blood glucose, lipids, insulin, liver function tests, renal function tests and urinary pH value were performed or measured. Multivariate linear regression analyses was performed to investigate the correlation between urinary pH value and metabolic syndrome. Logistic multiple regression analysis was performed to explore the risk of metabolic syndrome for decreased urinary pH value. The metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel HI (NCEP ATP HI) criteria with modification appropriate for Asian population. Results Subjects with metabolic syndrome had higher waist circumference, body mass index, systolic blood pressure, serum fasting glucose, low-density lipoprotein-cholesterol,triglycerides and lower high-density lipoprotein-cholesterol, urinary pH value than subjects without metabolic syndrome. Pearson's correlation analysis indicated that urinary pH value was negatively correlated with waist circumference, triglycerides, insulin resistance index and positively correlated with high-density lipoprotein-cholesterol. With the increase in components of metabolic syndrome, urinary pH value decreased both in men and women (P for trend<0.001). logistic regression analysis indicated that central obesity, hypertriglycerides, hypertension and hyperglycemia were the influencing factors of low urinary pH value. Subjects with metabolic syndrome had higher risk of having decreased urinary pH value [odds ratio (OR) = 1.42;95% confidence interval (CI): 1.19-1.70]. Conclusions Metabolic syndrome is associated with decreased urinary pH value in middle-aged and

  16. Characterization of the tail of the distribution of earthquake magnitudes by combining the GEV and GPD descriptions of Extreme Value Theory

    CERN Document Server

    Pisarenko, V F; Sornette, D; Rodkin, M V

    2008-01-01

    We present a generic and powerful approach to study the statistics of extreme phenomena (meteorology, finance, biology...) that we apply to the statistical estimation of the tail of the distribution of earthquake sizes. The chief innovation is to combine the two main limit theorems of Extreme Value Theory (EVT) that allow us to derive the distribution of T-maxima (maximum magnitude occurring in sequential time intervals of duration T) for arbitrary T. We propose a method for the estimation of the unknown parameters involved in the two limit theorems corresponding to the Generalized Extreme Value distribution (GEV) and to the Generalized Pareto Distribution (GPD). We establish the direct relations between the parameters of these distributions, which permit to evaluate the distribution of the T-maxima for arbitrary T. The duality between the GEV and GPD provides a new way to check the consistency of the estimation of the tail characteristics of the distribution of earthquake magnitudes for earthquake occurring ...

  17. Water-, pH- and temperature relations of germination for the extreme xerophiles Xeromyces bisporus (FRR 0025), Aspergillus penicillioides (JH06THJ) and Eurotium halophilicum (FRR 2471)

    NARCIS (Netherlands)

    Stevenson, Andrew; Hamill, Philip G; Dijksterhuis, Jan; Hallsworth, John E

    2016-01-01

    Water activity, temperature and pH are determinants for biotic activity of cellular systems, biosphere function and, indeed, for all life processes. This study was carried out at high concentrations of glycerol, which concurrently reduces water activity and acts as a stress protectant, to

  18. Multidimensional extremal dependence coefficients

    OpenAIRE

    2017-01-01

    Extreme values modeling has attracting the attention of researchers in diverse areas such as the environment, engineering, or finance. Multivariate extreme value distributions are particularly suitable to model the tails of multidimensional phenomena. The analysis of the dependence among multivariate maxima is useful to evaluate risk. Here we present new multivariate extreme value models, as well as, coefficients to assess multivariate extremal dependence.

  19. Cadmium availability in rice paddy fields from a mining area: The effects of soil properties highlighting iron fractions and pH value.

    Science.gov (United States)

    Yu, Huan-Yun; Liu, Chuanping; Zhu, Jishu; Li, Fangbai; Deng, Dong-Mei; Wang, Qi; Liu, Chengshuai

    2016-02-01

    Cadmium (Cd) availability can be significantly affected by soil properties. The effect of pH value on Cd availability has been confirmed. Paddy soils in South China generally contain high contents of iron (Fe). Thus, it is hypothesized that Fe fractions, in addition to pH value, may play an important role in the Cd bioavailability in paddy soil and this requires further investigation. In this study, 73 paired soil and rice plant samples were collected from paddy fields those were contaminated by acid mine drainage containing Cd. The contents of Fe in the amorphous and DCB-extractable Fe oxides were significantly and negatively correlated with the Cd content in rice grain or straw (excluding DCB-extractable Fe vs Cd in straw). In addition, the concentration of HCl-extractable Fe(II) derived from Fe(III) reduction was positively correlated with the Cd content in rice grain or straw. These results suggest that soil Fe redox could affect the availability of Cd in rice plant. Contribution assessment of soil properties to Cd accumulation in rice grain based on random forest (RF) and stochastic gradient boosting (SGB) showed that pH value should be the most important factor and the content of Fe in the amorphous Fe oxides should be the second most important factor in affecting Cd content in rice grain. Overall, compared with the studies from temperate regions, such as Europe and northern China, Fe oxide exhibited its unique role in the bioavailability of Cd in the reddish paddy soil from our study area. The exploration of practical remediation strategies for Cd from the perspective of Fe oxide may be promising. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. What do I want to be with my PhD? The roles of personal values and structural dynamics in shaping the career interests of recent biomedical science PhD graduates.

    Science.gov (United States)

    Gibbs, Kenneth D; Griffin, Kimberly A

    2013-01-01

    Interest in faculty careers decreases as graduate training progresses; however, the process underlying career-interest formation remains poorly defined. To better understand this process and whether/how it differs across social identity (i.e., race/ethnicity, gender), we conducted focus groups with 38 biomedical scientists who received PhDs between 2006 and 2011, including 23 women and 18 individuals from underrepresented minority (URM) backgrounds. Objective performance and quality of advisor relationships were not significantly different between scientists with high versus low interest in faculty careers. Career interests were fluid and formed in environments that generally lacked structured career development. Vicarious learning shaped similar outcome expectations about academic careers for all scientists; however, women and URMs recounted additional, distinct experiences and expectations. Scientists pursuing faculty careers described personal values, which differed by social identity, as their primary driver. For scientists with low interest in faculty careers, a combination of values, shared across social identity, and structural dynamics of the biomedical workforce (e.g., job market, grant funding, postdoc pay, etc.) played determinative roles. These findings illuminate the complexity of career choice and suggest attracting the best, most diverse academic workforce requires institutional leaders and policy makers go beyond developing individual skill, attending to individuals' values and promoting institutional and systemic reforms.

  1. APPLICATION OF EXTREME VALUE THEORY AND FUNDAMENTAL ANALYSIS IN LONG-SHORT STRATEGIES: AN ANALYSIS OF PAIR TRADINGS IN THE BRAZILIAN MARKET

    Directory of Open Access Journals (Sweden)

    Danilo Soares Monte-Mor

    2014-09-01

    Full Text Available In recent decades, the number of funds has increased which aim to explore market inefficiencies through arbitrage strategies, among which the long-short strategy stands out. A large part of the analyses used to obtain the pair tradings, however, does not consider the extreme deviations that exist in the interdependence process between the assets involved and the firms’ operational quality indicators. The Extreme Value Theory and Fundamental Analysis were used in this study to model the series of the asset pair price indices obtained based on the accounting indicator structure proposed by Piotroski (2000. These approaches permitted considering companies with positive signs of profitability, an operational capital structure and efficiency, besides distributions that are capable of capturing the extreme co-movements associated with the selected pair tradings. Based on this model, a new quantitative approach was created for the long-short strategy, called the GEV Long-Short. The obtained results suggest that the best adjustment of the extreme quantiles through the extreme value distribution can provide more refined probabilistic support for the return to the average to justify the possibility of long-short arbitrage.

  2. Effect of weak acid preservatives on growth of bakery product spoilage fungi at different water activities and pH values

    DEFF Research Database (Denmark)

    Suhr, Karin Isabel; Nielsen, Per Væggemose

    2004-01-01

    of bakery products was conducted using calcium propionate, potassium sorbate and sodium benzoate. The obtained data was modelled using survival analysis to determine 'spoilage-free time' for the fungi. At the low a(w) level (0.80) only Eurotium species grew within the test period of 30 days. Higher water...... activity levels as well as higher pH values decreased spoilage-free times of the fungi. The preservative calcium propionate was less effective than potassium sorbate and sodium benzoate....

  3. Specific detection of cysteine and homocysteine in biological fluids by tuning the pH values of fluorosurfactant-stabilized gold colloidal solution.

    Science.gov (United States)

    Xiao, Qunyan; Shang, Fei; Xu, Xuechen; Li, Qianqian; Lu, Chao; Lin, Jin-Ming

    2011-12-15

    This study describes the use of 14 nm nonionic fluorosurfactant-capped gold nanoparticles (FSN-capped AuNPs) for the simultaneous detection of cysteine (Cys) and homocysteine (Hcy) using colorimetric method, requiring no use of separation techniques. It was found that the kinetics of Cys/Hcy-induced aggregation of the 14 nm FSN-capped AuNPs strongly depends on the pH value of gold colloidal solution. At a pH of 6.5, the Cys-induced aggregation kinetics of the FSN-capped AuNPs was almost identical to that induced by Hcy, facilitating simultaneous detection of total Cys and Hcy up to a concentration as low as 0.15 μM; while at pH 12.0, the kinetics of Cys-induced aggregation was much faster than that inducted by Hcy, leading to selective detection of Cys at concentration as low as 1.0 μM in the presence of Hcy. The applicability of the method was validated by spiking known amount of Cys and Hcy in human urine and plasma samples, obtaining a recovery of 95.4-105.5%. The present approach is simple, high selective and provides high reproducibility, and has a great potentiality in disease diagnosis.

  4. Metal accumulation and oxidative stress biomarkers in liver of freshwater fish Carassius auratus following in vivo exposure to waterborne zinc under different pH values.

    Science.gov (United States)

    Qu, Ruijuan; Feng, Mingbao; Wang, Xinghao; Qin, Li; Wang, Chao; Wang, Zunyao; Wang, Liansheng

    2014-05-01

    In this study, laboratory experiments were conducted to investigate the combined effect of zinc and pH on metal accumulation and oxidative stress biomarkers in Carassius auratus. Fish were exposed to 0.1 and 1.0mg Zn/L at three pH values (5.0, 7.25, 9.0) for 3, 12, and 30 d. After each exposure, the contents of three trace elements (Zn, Fe and Cu) were determined in liver. Generally, longer exposure to zinc (12d and 30 d) increased hepatic Zn and Cu deposition, but decreased Fe content. Increasing accumulation of Zn in the tissue was also observed with increasing zinc concentration in the exposure medium. Moreover, hepatic antioxidant enzyme activities including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), together with the level of glutathione (GSH) were measured to evaluate the oxidative stress status. The decreases in the four measured biochemical parameters after 3d exposure might reflect the failure of the antioxidant defense system in neutralizing the ROS generated during the metabolic process, while the recovery of the antioxidants at days 12 and 30 suggested a possible shift toward a detoxification mechanism. With regard to the influence of pH on zinc toxicity, the general observation was that the living environment became more stressful when the water conditions changed from an acidic state toward a near-neutral or alkaline state.

  5. Enzyme-regulated the changes of pH values for assembling a colorimetric and multistage interconnection logic network with multiple readouts

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yanyan; Ran, Xiang; Lin, Youhui [Laboratory of Chemical Biology, Division of Biological Inorganic Chemistry, State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Graduate School of University of Chinese Academy of Sciences, Beijing 100039 (China); Ren, Jinsong, E-mail: jren@ciac.ac.cn [Laboratory of Chemical Biology, Division of Biological Inorganic Chemistry, State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Qu, Xiaogang [Laboratory of Chemical Biology, Division of Biological Inorganic Chemistry, State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China)

    2015-04-22

    Highlights: • A colorimetric and multistage biological network has been developed. • This system was on the basis of the enzyme-regulated changes of pH values. • This enzyme-based system could assemble large biological circuit. • Two signal transducers (DNA/AuNPs and acid–base indicators) were used. • The compositions of samples could be detected through visual output signals. - Abstract: Based on enzymatic reactions-triggered changes of pH values and biocomputing, a novel and multistage interconnection biological network with multiple easy-detectable signal outputs has been developed. Compared with traditional chemical computing, the enzyme-based biological system could overcome the interference between reactions or the incompatibility of individual computing gates and offer a unique opportunity to assemble multicomponent/multifunctional logic circuitries. Our system included four enzyme inputs: β-galactosidase (β-gal), glucose oxidase (GOx), esterase (Est) and urease (Ur). With the assistance of two signal transducers (gold nanoparticles and acid–base indicators) or pH meter, the outputs of the biological network could be conveniently read by the naked eyes. In contrast to current methods, the approach present here could realize cost-effective, label-free and colorimetric logic operations without complicated instrument. By designing a series of Boolean logic operations, we could logically make judgment of the compositions of the samples on the basis of visual output signals. Our work offered a promising paradigm for future biological computing technology and might be highly useful in future intelligent diagnostics, prodrug activation, smart drug delivery, process control, and electronic applications.

  6. Hybrid hard- and soft-modeling of spectrophotometric data for monitoring of ciprofloxacin and its main photodegradation products at different pH values

    Science.gov (United States)

    Razuc, Mariela; Garrido, Mariano; Caro, Yamile S.; Teglia, Carla M.; Goicoechea, Héctor C.; Fernández Band, Beatriz S.

    2013-04-01

    A simple and fast on line spectrophotometric method combined with a hybrid hard-soft modeling multivariate curve resolution (HS-MCR) was proposed for the monitoring of photodegradation reaction of ciprofloxacin under UV radiation. The studied conditions attempt to emulate the effect of sunlight on these antibiotics that could be eventually present in the environment. The continuous flow system made it possible to study the ciprofloxacin degradation at different pH values almost at real time, avoiding errors that could arise from typical batch monitoring of the reaction. On the base of a concentration profiles obtained by previous pure soft-modeling approach, reaction pathways have been proposed for the parent compound and its photoproducts at different pH values. These kinetic models were used as a constraint in the HS-MCR analysis. The kinetic profiles and the corresponding pure response profile (UV-Vis spectra) of ciprofloxacin and its main degradation products were recovered after the application of HS-MCR analysis to the spectra recorded throughout the reaction. The observed behavior showed a good agreement with the photodegradation studies reported in the bibliography. Accordingly, the photodegradation reaction was studied by high performance liquid chromatography coupled with UV-Vis diode array detector (HPLC-DAD). The spectra recorded during the chromatographic analysis present a good correlation with the ones recovered by UV-Vis/HS-MCR method.

  7. pH value manipulated phase transition, microstructure evolution and tunable upconversion luminescence in Yb(3+)-Er(3+) codoped LiYF4/YF3 nanoparticles.

    Science.gov (United States)

    Ye, Song; Hu, Rongxuan; Jiang, Nan; Wang, Huiyun; Wang, Deping

    2015-09-21

    The pH value plays an important role in controlling the crystallization process and microstructure of the final products in the synthesis of nanocrystals with a solvothermal method. This work reported the effect of the mother solution pH value on the precipitation of LiYF4 and YF3 nanoparticles, as well as the microstructure evaluation of YF3 from a bowknot-like to spindle-like shape. Spectroscopy study suggests that there is strong correlation between the upconversion emission properties of the Yb(3+)-Er(3+) couple and the phase and the microstructure of the host. The strongest emissions and lowest red-to-green ratio are observed in the bowknot-like YF3 nanocrystals with the largest open ends. Further spectral investigation indicates that the phase and microstructure dependent upconversion properties are associated with the upconversion efficiency. The present study is of great importance in the design and synthesis of rare earth ion doped nanocrystals with tunable upconversion properties.

  8. Ultimate pH values and bacteriological condition of meat and stress metabolites in blood of transported reindeer bulls

    Directory of Open Access Journals (Sweden)

    E. Wiklund

    2001-03-01

    Full Text Available Twenty-three reindeer bulls, aged 2-3 years, fed during two winter months at the Vuolda reindeer research station in Arjeplog, Sweden, were used in the study. The first group of eight reindeer was moved from their feeding corral to a selection corral, captured by lasso and stunned with a captive bolt outside the selection corral. The second group of seven reindeer was moved to the selection corral, captured by lasso and restrained, after which they were loaded onto a lorry- and transported for 1 hour and then slaughtered. The third group of eight reindeer was moved to the selection corral and herded directly onto the lorry, without any manual handling. They were transported for 5 h and then slaughtered. In both transport groups, four reindeer were fitted with pre-programmed automatic blood sampling equipment (ABSE. ABSE sampled blood at predetermined times via a jugular vein catheter. Ultimate pH-values in three muscles (Mm. longissimus, triceps brachii and biceps femoris were significantly lower in the group carefully handled and transported for 5 h compared with the other two groups. The physiological mechanisms behind these results are discussed. Samples from M. semimembranosus were collected at slaughter and after 2, 6 and 10 days of refrigerated storage (+4 °C. The samples were analysed for total counts of aerobic bacteria (pour-plated in Tryptone Glucose Extract Agar, Difco, incubated at 20 °C and 30 °C, respectively for 72 h, coliform bacteria 37 °C (pour-plated in Violet Red Bile Agar, Oxoid, incubated at 37 °C for 24 h, Enterococci (surface-plated onto Slantez and Bartley Agar, Oxoid, incubated at 44 °C for 48 h and Bacillus cereus (surface-plated onto Blood Agar Plates (Blood Agar Base, Difco, supplemented with 5% defibrinated horse blood 30 °C for 24 h. All samples fell in the range 'fit for consumption'. At slaughter, there was no difference in ASAT activity, urea and Cortisol concentrations between the two transported groups

  9. Several Inequalities for Moments of Extreme Values of Samples%关于样本极值的矩的几个不等式

    Institute of Scientific and Technical Information of China (English)

    康殿统

    2006-01-01

    Several inequalities for moments of extreme values of samples extracted from two starshaped ordered populations are extended by replacing the star-shaped order with the NBUE (new better that used in expectation) order.%把在星形序下成立的关于样本极值的几个矩的不等式推广到了在NBUE序下也成立.

  10. Enzyme-regulated the changes of pH values for assembling a colorimetric and multistage interconnection logic network with multiple readouts.

    Science.gov (United States)

    Huang, Yanyan; Ran, Xiang; Lin, Youhui; Ren, Jinsong; Qu, Xiaogang

    2015-04-22

    Based on enzymatic reactions-triggered changes of pH values and biocomputing, a novel and multistage interconnection biological network with multiple easy-detectable signal outputs has been developed. Compared with traditional chemical computing, the enzyme-based biological system could overcome the interference between reactions or the incompatibility of individual computing gates and offer a unique opportunity to assemble multicomponent/multifunctional logic circuitries. Our system included four enzyme inputs: β-galactosidase (β-gal), glucose oxidase (GOx), esterase (Est) and urease (Ur). With the assistance of two signal transducers (gold nanoparticles and acid-base indicators) or pH meter, the outputs of the biological network could be conveniently read by the naked eyes. In contrast to current methods, the approach present here could realize cost-effective, label-free and colorimetric logic operations without complicated instrument. By designing a series of Boolean logic operations, we could logically make judgment of the compositions of the samples on the basis of visual output signals. Our work offered a promising paradigm for future biological computing technology and might be highly useful in future intelligent diagnostics, prodrug activation, smart drug delivery, process control, and electronic applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Sensory meat quality, ultimate pH values, blood metabolites and carcass parametersin reindeer (Rangifer tarandus tarandus L. fed various diets

    Directory of Open Access Journals (Sweden)

    Eva Wiklund

    2000-03-01

    Full Text Available This investigation was made to study and compare the effects of different diets on sensory meat quality and ultimate pH values in reindeer muscles and to relate stress-induced blood metabolites and carcass parameters to the meat quality traits measured. Altogether 23 female reindeer calves were included in the study. During an adaptation period, all reindeer were allowed free access to a mimicked natural diet containing 80% lichens (lichen diet. On January 28, 8 reindeer (group Cjan were slaughtered. Five reindeer (group C.Mar were allowed continuous free access to the lichen diet throughout the experiment. During 8 days, the other reindeer (groups PL and PS were given the lichen diet, half of the amount offered to the control group, and were then starved for one day. Thereafter, these reindeer were fed 80% commercial reindeer feed (pellets and either 20% lichens (group PL, or 20% silage (group PS for 5 weeks. After this, all animals were slaughtered. The average carcass weight and dressing percentage in the group fed commercial reindeer feed and lichens (PL were higher than in group CMar- Fat registrations were generally higher in groups PL and PS than in the groups Cj2n and CMar- Ultimate pH values in M. triceps brachii and M. longissimus were significantly lower in the group CMST than in PL. The levels of all blood metabolites (urea, ASAT and Cortisol were generally higher in groups PL and PS than in groups Cja„ and CMEF- NO significant differences were found in any of sensory attributes of the meat (monitored according to ISO standards. The present study shows that muscle and fat depots in reindeer can be improved by feeding a diet based on reindeer pellets but suggests that a feeding period of 35 days might be too short to affect the sensory properties of reindeer meat.

  12. [Influences of the mobile phase constitution, salt concentration and pH value on retention characters of proteins on the metal chelate column].

    Science.gov (United States)

    Li, R; Di, Z M; Chen, G L

    2001-09-01

    The effects of the nature and concentration of salts, pH value and competitive eluent in the mobile phase on the protein retention have been systematically investigated. A mathematical expression describing the protein retention in metal chelate chromatography has been derived. It is proposed that the eluting power of the salt solution can be expressed by the eluent strength exponent epsilon. According to the retention characters of protein under different chromatographic conditions, the interaction between the various metal chelate ligands and proteins is discussed. The protein retention on the metal chelate column is a cooperative interactions of coordination, electrostatic and hydrophobic interaction. For the strong combined metal column with proteins such as IDA-Cu, the coordination is the most important, and the electrostatic interaction is secondary in chromatographic process. However, for the weak combined metal columns with proteins such as IDA-Ni, IDA-Co and IDA-Zn, the electrostatic interaction between the metal chelate ligands and proteins is the chief one, while the coordination is the next in importance. When the mobile phase contains high concentration of salt which can't form complex with the immobilized metal, the hydrophobic interaction between the protein and stationary phase will be increased. As the interaction between the metal chelate ligand and proteins relates to chromatographic operating conditions closely, different elution processes may be selected for different metal chelate columns. The gradient elution is generally performed by the low concentration of salt or different pH for weakly combined columns with proteins, however the competitive elution procedure is commonly utilized for strongly combined column. The experiment showed that NH3 is an excellent competitive eluent. It isn't only give the efficient separation of proteins, but also has the advantages of cheapness, less bleeding of the immobilized metals and ease of controlling NH3

  13. Effects of different pH values on seedling morphology and physiological characteristics of Vetiveria zizanioides under hydroponic culture%水培条件下不同 pH 值对香根草幼苗形态和生理特性的影响

    Institute of Scientific and Technical Information of China (English)

    王青青; 周强; 於丙军

    2014-01-01

    part of leaf apexes with a little chlorosis and root morphology without obvious change except color under conditions of weak alkalinity ( pH 9. 0 and pH 8. 0) and weak acidity (pH 5. 0 and pH 4. 0). With pH value of solution increasing ( alkalinity increasing) or decreasing (acidity increasing), both leaf water content and chlorophyll content decrease gradually and are lower than those of the control (pH 6. 5), while both relative electrolytic leakage and MDA content increase gradually and are higher than those of the control. In general, there are significant (P0. 05) difference in all indexes under conditions of weak alkalinity (pH 9. 0 and pH 8. 0) and weak acidity (pH 5. 0 and pH 4. 0) with the control. With pH value of solution increasing ( alkalinity increasing ) or decreasing ( acidity increasing), both the maximum root length and root activity decrease gradually. Under conditions of weak alkalinity (pH 8. 0) and weak acidity (pH 5. 0), the maximum root length is slightly lower than that of the control and root activity is slightly higher than that of the control without significant difference. Under pH 9. 0-pH 11. 0 and pH 4. 0-pH 2. 0, both the maximum root length and root activity are significantly lower than those of the control, in which root length is the shortest and root activity is the smallest under pH 11. 0, with 60. 50% and 9. 52% of the control,respectively. It is suggested that V. zizanioides has a wide adaptation range to acidity-alkalinity of soil, and can adapt soil habitat with pH 4. 0-pH 9. 0.

  14. 17-4 PH and 15-5 PH

    Science.gov (United States)

    Johnson, Howard T.

    1995-01-01

    17-4 PH and 15-5 PH are extremely useful and versatile precipitation-hardening stainless steels. Armco 17-4 PH is well suited for the magnetic particle inspection requirements of Aerospace Material Specification. Armco 15-5 PH and 17-4 PH are produced in billet, plate, bar, and wire. Also, 15-5 PH is able to meet the stringent mechanical properties required in the aerospace and nuclear industries. Both products are easy to heat treat and machine, making them very useful in many applications.

  15. Low temperature lignocellulose pretreatment: effects and interactions of pretreatment pH are critical for maximizing enzymatic monosaccharide yields from wheat straw

    DEFF Research Database (Denmark)

    Pedersen, Mads; Johansen, Katja S.; Meyer, Anne S.

    2011-01-01

    C for 10 min. The maximal enzymatic glucose and xylose yields from the solid, pretreated wheat straw fraction were obtained after pretreatments at the most extreme pH values (pH 1 or pH 13) at the maximum pretreatment temperature of 140 degrees C. Surface response models revealed significantly...

  16. The value of crossdating to retain high-frequency variability, climate signals, and extreme events in environmental proxies.

    Science.gov (United States)

    Black, Bryan A; Griffin, Daniel; van der Sleen, Peter; Wanamaker, Alan D; Speer, James H; Frank, David C; Stahle, David W; Pederson, Neil; Copenheaver, Carolyn A; Trouet, Valerie; Griffin, Shelly; Gillanders, Bronwyn M

    2016-07-01

    High-resolution biogenic and geologic proxies in which one increment or layer is formed per year are crucial to describing natural ranges of environmental variability in Earth's physical and biological systems. However, dating controls are necessary to ensure temporal precision and accuracy; simple counts cannot ensure that all layers are placed correctly in time. Originally developed for tree-ring data, crossdating is the only such procedure that ensures all increments have been assigned the correct calendar year of formation. Here, we use growth-increment data from two tree species, two marine bivalve species, and a marine fish species to illustrate sensitivity of environmental signals to modest dating error rates. When falsely added or missed increments are induced at one and five percent rates, errors propagate back through time and eliminate high-frequency variability, climate signals, and evidence of extreme events while incorrectly dating and distorting major disturbances or other low-frequency processes. Our consecutive Monte Carlo experiments show that inaccuracies begin to accumulate in as little as two decades and can remove all but decadal-scale processes after as little as two centuries. Real-world scenarios may have even greater consequence in the absence of crossdating. Given this sensitivity to signal loss, the fundamental tenets of crossdating must be applied to fully resolve environmental signals, a point we underscore as the frontiers of growth-increment analysis continue to expand into tropical, freshwater, and marine environments. © 2016 John Wiley & Sons Ltd.

  17. Observation of pH Value in Electrokinetic Remediation using various electrolyte (MgSO4, KH2PO4 and Na(NO3)) for Barren Acidic Soil at Ayer Hitam, Johor, Malaysia

    Science.gov (United States)

    Norashira, J.; Zaidi, E.; Aziman, M.; Saiful Azhar, A. T.

    2016-07-01

    Barren acidic soil collected at Ayer Hitam, Johor Malaysia was recorded at pH value of 2.36 with relative humidity of 86%. This pH value is not suitable for the growth of any plants especially for the soil stabilization purposes. Gradation weathering within the range of 4 to 6 indicates an incomplete/partial weathering process. The soil grade in this range is known as a black shale mudstone. Beside, this also influences to a factor of the high surface water runoff at this particular soil species. As the acidic pH become a major problem for soil fertilizing hence an appropriate technique was implemented known as using ‘Electrokinetic Remediation’, EKR. This technique has a great potential in changing the soil pH value from acidic to less acidic and also kept maintain the pH at the saturated rate of electrochemical process. This research study presents the monitoring data of pH value due to the effect of various electrolyte consist of 0.5M of MgSO4, KH2PO4, and Na(NO3). Here, the distilled water (DW) was used as reference solution. The electric field was provided by dipping two pieces of identical rectangular aluminum foil as anode and cathode. The EKR was conducted under a constant voltage gradient of 50 V/m across the sample bulk at 0.14 m length measured between both electrodes. The data collection was conducted during the total period of 7 days surveillance. The variation of pH values at the remediation area between anode and cathode for various type of electrolyte indicates that there are a significant saturated value as it reaches 7 days of treatment. During the analysis, it is found that the highest pH value at the remediation area after 7 days treatment using Na(NO3), KH2PO4 and MgSO4 was 3.93, 3.33 and 3.39 respectively. Hence from the last stage of pH value observation, it can be conclude that the best electrolyte for barren soil treatment is Na(NO3) whereby it contribute to highest pH value and turn the soil to be less acidic.

  18. On the distribution of extreme values of zeta and $L$-functions in the strip $1/2<\\sigma<1$

    CERN Document Server

    Lamzouri, Youness

    2010-01-01

    We study the distribution of large (and small) values of several families of $L$-functions on a line $\\text{Re(s)}=\\sigma$ where $1/2<\\sigma<1$. We consider the Riemann zeta function $\\zeta(s)$ in the $t$-aspect, Dirichlet $L$-functions in the $q$-aspect, and $L$-functions attached to primitive holomorphic cusp forms of weight $2$ in the level aspect. For each family we show that the $L$-values can be very well modeled by an adequate random Euler product, uniformly in a wide range. We also prove new $\\Omega$-results for quadratic Dirichlet $L$-functions (predicted to be best possible by the probabilistic model) conditionally on GRH, and other results related to large moments of $\\zeta(\\sigma+it)$.

  19. LIL and the Approximation of Rectangular Sums of B-valued Random Variables when Extreme Terms are Excluded

    Institute of Scientific and Technical Information of China (English)

    Li Xin ZHANG

    2002-01-01

    Let {X, Xa; X-n;-n∈ Nd} be a field of i.i.d. random variables indexed by d-tuples of positiveintegers and taking values in a Banach spaceB and let X(r)-n = X-m if ‖X-m‖ is the r-th maximum ofsums (r)S-n by a Brownian sheet and obtain sufficient and necessary conditions for (r)S-n to satisfy thecompact and functional laws of the iterated logarithm. These results improve the previous works byMorrow (1981), Li and Wu (1989) and Ledoux and Talagrand (1990).

  20. Glucose intolerance in dairy goats with pregnancy toxemia: Lack of correlation between blood pH and beta hydroxybutyric acid values.

    Science.gov (United States)

    Lima, Miguel S; Cota, João B; Vaz, Yolanda M; Ajuda, Inês G; Pascoal, Rita A; Carolino, Nuno; Hjerpe, Charles A

    2016-06-01

    This study assessed the response to a glucose tolerance test in dairy goats with pregnancy toxemia (PT), in healthy, pregnant, non-lactating dairy goats in the last month of gestation (HP), and in healthy, lactating, non-pregnant, dairy goats in mid-lactation (HL). A 500 mL volume of a 5% glucose solution was administered by the IV route. Blood glucose concentrations returned to pre-infusion levels by 90 min in all 8 HL goats, and by 180 min in all 8 HP goats. In contrast, concentrations of blood glucose were still significantly above pre-infusion levels at 180 min post-infusion in all 8 PT goats. Thus, marked glucose intolerance was demonstrated in the PT goats, and mild intolerance was noted in the HP goats. In 25 goats diagnosed with PT and having blood beta hydroxybutyric acid (BHBA) values ≥ 2.9 mmol/L, the correlation coefficient for BHBA with blood pH was non-significant.

  1. Influence of nitrogen source and pH value on undesired poly(γ-glutamic acid) formation of a protease producing Bacillus licheniformis strain.

    Science.gov (United States)

    Meissner, Lena; Kauffmann, Kira; Wengeler, Timo; Mitsunaga, Hitoshi; Fukusaki, Eiichiro; Büchs, Jochen

    2015-09-01

    Bacillus spp. are used for the production of industrial enzymes but are also known to be capable of producing biopolymers such as poly(γ-glutamic acid). Biopolymers increase the viscosity of the fermentation broth, thereby impairing mixing, gas/liquid mass and heat transfer in any bioreactor system. Undesired biopolymer formation has a significant impact on the fermentation and downstream processing performance. This study shows how undesirable poly(γ-glutamic acid) formation of an industrial protease producing Bacillus licheniformis strain was prevented by switching the nitrogen source from ammonium to nitrate. The viscosity was reduced from 32 to 2.5 mPa s. A constant or changing pH value did not influence the poly(γ-glutamic acid) production. Protease production was not affected: protease activities of 38 and 46 U mL(-1) were obtained for ammonium and nitrate, respectively. With the presented results, protease production with industrial Bacillus strains is now possible without the negative impact on fermentation and downstream processing by undesired poly(γ-glutamic acid) formation.

  2. 盐酸多西环素注射液最稳定pH值研究%A Study of the Stable pH Value of Doxycycline Hydrochloride Injection

    Institute of Scientific and Technical Information of China (English)

    胡海燕; 王亦琳; 黄耀凌; 徐倩; 徐士新; 朱馨乐; 朱明文

    2014-01-01

    The stable pH value of the veterinary doxycycline hydrochloride injection was predicted. The chemical stability of doxycycline hydrochloride injection was studied in the extensive pH range by classical isothermal kinetic method and single point kinetic method. The relationship between stability and pH value of the injection was investigated. The results showed that, the most stable pH value and stable pH range that predicted by the two methods were basically identical. The most stable pH value of doxycycline hydrochloride injection was 4.0. Single point kinetic method was simple and its workload was small compared with the classical kinetic method.%预测了兽用盐酸多西环素注射液稳定pH值。在广泛pH范围内,采用经典恒温法和单测点法对所研制的盐酸多西环素注射液进行化学稳定性研究,探讨pH值与稳定性之间的关系。结果表明,这两种方法预测的稳定 pH 值及稳定 pH 值范围基本一致,盐酸多西环素注射液最稳定pH值[( pH) m]为4.0,与经典法比较,单侧点法工作量小,简单易行。

  3. Impact of pH on Microbial Biomass Carbon and Microbial Biomass Phosphorus in Red Soils

    Institute of Scientific and Technical Information of China (English)

    CHEN Guo-Chao; HE Zhen-Li; WANG Yi-Jun

    2004-01-01

    The impact of pH changes on microbial biomass carbon (Cmic) and microbial biomass phosphorus (Pmic)were examined for 3 red soils under citrus production with different lengths of cultivation. Soil pH significantly affected Cmic and Pmic. The Cmic and Pmic changes, as a function of soil pH, appeared to follow a normal distribution with the original soil pH value at the apex and as pH increased or decreased compared to the original soil pH, Cmic and Pmic declined. Moreover, there were critical pH values at both extremes (3.0 on the acidic side and 8.0 to 8.5 on the alkaline side), beyond which most of microorganisms could never survive.The effect of pH on Cmic and Pmic was also related to the original soil pH. The higher the original soil pH was, the less Cmic or Pmic were affected by pH change. It is suggested that soil microorganisms that grow in a soil environment with a more neutral soil pH range (I.e. pH 5.5-7.5) may have a greater tolerance to pH changes than those growing in more acidic or more alkaline soil pH conditions.

  4. Impact of increasing heat waves on U.S. ozone episodes in the 2050s: Results from a multimodel analysis using extreme value theory

    Science.gov (United States)

    Shen, L.; Mickley, L. J.; Gilleland, E.

    2016-04-01

    We develop a statistical model using extreme value theory to estimate the 2000-2050 changes in ozone episodes across the United States. We model the relationships between daily maximum temperature (Tmax) and maximum daily 8 h average (MDA8) ozone in May-September over 2003-2012 using a Point Process (PP) model. At ~20% of the sites, a marked decrease in the ozone-temperature slope occurs at high temperatures, defined as ozone suppression. The PP model sometimes fails to capture ozone-Tmax relationships, so we refit the ozone-Tmax slope using logistic regression and a generalized Pareto distribution model. We then apply the resulting hybrid-extreme value theory model to projections of Tmax from an ensemble of downscaled climate models. Assuming constant anthropogenic emissions at the present level, we find an average increase of 2.3 d a-1 in ozone episodes (>75 ppbv) across the United States by the 2050s, with a change of +3-9 d a-1 at many sites.

  5. Illumina sequencing-based analyses of bacterial communities during short-chain fatty-acid production from food waste and sewage sludge fermentation at different pH values.

    Science.gov (United States)

    Cheng, Weixiao; Chen, Hong; Yan, ShuHai; Su, Jianqiang

    2014-09-01

    Short-chain fatty acids (SCFAs) can be produced by primary and waste activated sludge anaerobic fermentation. The yield and product spectrum distribution of SCFAs can be significantly affected by different initial pH values. However, most studies have focused on the physical and chemical aspects of SCFA production by waste activated sludge fermentation at different pH values. Information on the bacterial community structures during acidogenic fermentation is limited. In this study, comparisons of the bacterial communities during the co-substrate fermentation of food wastes and sewage sludge at different pH values were performed using the barcoded Illumina paired-end sequencing method. The results showed that different pH environments harbored a characteristic bacterial community, including sequences related to Lactobacillus, Prevotella, Mitsuokella, Treponema, Clostridium, and Ureibacillus. The most abundant bacterial operational taxonomic units in the different pH environments were those related to carbohydrate-degrading bacteria, which are associated with constituents of co-substrate fermentation. Further analyses showed that during organic matter fermentation, a core microbiota composed of Firmicutes, Proteobacteria, and Bacteroidetes existed. Comparison analyses revealed that the bacterial community during fermentation was significantly affected by the pH, and that the diverse product distribution was related to the shift in bacterial communities.

  6. What Do I Want to Be with My PhD? The Roles of Personal Values and Structural Dynamics in Shaping the Career Interests of Recent Biomedical Science PhD Graduates

    Science.gov (United States)

    Gibbs, Kenneth D., Jr.; Griffin, Kimberly A.

    2013-01-01

    Interest in faculty careers decreases as graduate training progresses; however, the process underlying career-interest formation remains poorly defined. To better understand this process and whether/how it differs across social identity (i.e., race/ethnicity, gender), we conducted focus groups with 38 biomedical scientists who received PhDs…

  7. What Do I Want to Be with My PhD? The Roles of Personal Values and Structural Dynamics in Shaping the Career Interests of Recent Biomedical Science PhD Graduates

    Science.gov (United States)

    Gibbs, Kenneth D., Jr.; Griffin, Kimberly A.

    2013-01-01

    Interest in faculty careers decreases as graduate training progresses; however, the process underlying career-interest formation remains poorly defined. To better understand this process and whether/how it differs across social identity (i.e., race/ethnicity, gender), we conducted focus groups with 38 biomedical scientists who received PhDs…

  8. The value of Anti-Müllerian hormone in low and extremely low ovarian reserve in relation to live birth after in vitro fertilization.

    Science.gov (United States)

    Reijnders, Igna F; Nelen, Willianne L D M; IntHout, Joanna; van Herwaarden, Antonius E; Braat, Didi D M; Fleischer, Kathrin

    2016-05-01

    To determine the relation of Anti-Müllerian hormone (AMH) with live birth after in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) in women with (extremely) low ovarian reserve. This study was a retrospective cohort study in a Dutch tertiary fertility clinic. Between January 2009 and March 2012, AMH levels were measured in infertile women when ≥36 years of age or when showing clinical signs of diminished ovarian reserve, before they underwent IVF or ICSI treatment. Ultimately, 156 women with (extremely) low ovarian reserve were included and evaluated for cumulative live birth rates. Of each woman, only one treatment cycle was analyzed, either the one in which she became pregnant or her first treatment cycle if she did not reach pregnancy. The relation between AMH and live birth was evaluated with multivariable logistic regression analysis. A ROC curve was composed to evaluate the discriminative value of AMH in relation to live birth after IVF/ICSI. Thirty-three out of 156 women (21.2%) gave live birth. Live birth was significantly lower in women with AMH ≤0.1ng/ml (4/37 women; 10.8%) or AMH >0.1-0.4ng/ml (7/42 women; 16.7%), compared to women with AMH >0.4-1.05ng/ml (22/77 women; 28.6%), plive birth (per 0.1ng/ml increase in AMH value, Odds ratio 1.21; 95% CI 1.07-1.36). The level of AMH is related to live birth after IVF/ICSI in women with (extremely) low ovarian reserve. The live birth rate in women with AMH >0.4ng/ml was significantly higher than in women with AMH ≤0.4ng/ml. AMH could serve as a tool in the pre-treatment counseling for pregnancy and live birth chances in women with (extremely) low ovarian reserve. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  9. Extreme value theory applied to the standardized precipitation index - doi: 10.4025/actascitechnol.v36i1.17475

    Directory of Open Access Journals (Sweden)

    Gabriel Constantino Blain

    2014-01-01

    Full Text Available The Standardized Precipitation Index (SPI is a mathematical algorithm developed for detecting and characterizing precipitation departures with regard to an expected regional climate condition. Thus, this study aimed to verify the possibility of using the time-independent general extreme value distribution (GEV for modeling the probability of occurrence of both SPI annual maxima (the maximum monthly SPI value; SPImax and SPI annual minima (the minimum monthly SPI value; SPImim obtained from the weather station of Campinas, State of São Paulo, Brazil (1891-2011 and to evaluate the presence of trends, temporal persistence and periodical components in these two datasets. The goodness-of-fit tests used in this study quantify the agreement between the empirical cumulative distribution and the GEV cumulative function. Our results have indicated that such parametric function can be used to assess the probability of occurrence of SPImin and SPImax values. No significant serial correlation and no trend were detected in both series. For the SPImim, the wavelet analysis has detected a dominant mode in the 4-8 year band. Future studies should focus on the development of a GEV model capable of accounting for such feature. No dominant mode was found for the annual monthly SPI maximums.

  10. Advances in the effects of pH value of micro-environment on wound healing%微环境pH值对创面愈合的作用研究进展

    Institute of Scientific and Technical Information of China (English)

    田瑞瑞; 李娜; 魏力

    2016-01-01

    Wound healing is a complex regeneration process,which is affected by lots of endogenous and exogenous factors.Researches have confirmed that acid environment could prevent wound infection and accelerate wound healing by inhibiting bacteria proliferation,promoting oxygen release,affecting keratinocyte proliferation and migration,etc.In this article,we review the literature to identify the potential relationship between the pH value of wound micro-environment and the progress of wound healing,and summarize the clinical application of variation of pH value of micro-environment in wound healing,thereby to provide new treatment strategy for wound healing.

  11. The diagnostic value of time-resolved MR angiography with Gadobutrol at 3 T for preoperative evaluation of lower extremity tumors: Comparison with computed tomography angiography.

    Science.gov (United States)

    Wu, Gang; Jin, Teng; Li, Ting; Li, Xiaoming

    2016-01-01

    To evaluate the diagnostic value of time resolved magnetic resonance angiography with interleaved stochastic trajectory (TWIST) using Gadobutrol for preoperative evaluation of lower extremity tumors. This prospective study was approved by the local Institutional Review Board. 50 consecutive patients (31 men, 19 women, age range 18-80 years, average age 42.7 years) with lower extremity tumors underwent TWIST and computed tomography angiography (CTA). Image quality of TWIST and CTA were evaluated by two radiologists according to a 4-point scale. The degree of arterial stenosis caused by tumor was assessed using TWSIT and CTA separately, and the intra-modality agreement was determined using a kappa test. The number of feeding arteries identified by TWIST was compared with that by CTA using Wilcoxon signed rank test. The ability to identify arterio-venous fistulae (AVF) were compared using a chi-square test. Image quality of TWIST and CTA were rated as 3.88 ± 0.37 and 3.97 ± 0.16, without statistically significant difference (P = 0.135). Intra-modality agreement was excellent for the assessment of arterial stenosis (kappa = 0.806 ± 0.073 for Reader 1, kappa = 0.805 ± 0.073 for Reader 2). Readers identified AVF with TWIST in 27 of 50 cases, and identified AVF with CTA in 14 of 50 (P < 0.001). Mean feeding arteries identified with TWIST was significantly more than that with CTA (2.08 ± 1.72 vs 1.62 ± 1.52, P = 0.02). TWIST is a reliable imaging modality for the assessment of lower extremity tumors. TWIST is comparable to CTA for the identification of AVF and feeding arteries.

  12. How extreme are extremes?

    Science.gov (United States)

    Cucchi, Marco; Petitta, Marcello; Calmanti, Sandro

    2016-04-01

    High temperatures have an impact on the energy balance of any living organism and on the operational capabilities of critical infrastructures. Heat-wave indicators have been mainly developed with the aim of capturing the potential impacts on specific sectors (agriculture, health, wildfires, transport, power generation and distribution). However, the ability to capture the occurrence of extreme temperature events is an essential property of a multi-hazard extreme climate indicator. Aim of this study is to develop a standardized heat-wave indicator, that can be combined with other indices in order to describe multiple hazards in a single indicator. The proposed approach can be used in order to have a quantified indicator of the strenght of a certain extreme. As a matter of fact, extremes are usually distributed in exponential or exponential-exponential functions and it is difficult to quickly asses how strong was an extreme events considering only its magnitude. The proposed approach simplify the quantitative and qualitative communication of extreme magnitude

  13. The Maximum Power of the Wind Power System Based on Extreme Value Method%基于极值法的风电系统最大功率

    Institute of Scientific and Technical Information of China (English)

    陆玲黎; 吴雷

    2011-01-01

    针对风力发电系统的最大功率问题,提出以极值法为依据捕获最大功率的方法.分析了风力机的工作原理及功率特性,讨论了影响功率的主要因素.通过对极值搜索法的基本理论及特点的解析,结合其工作原理,得出功率曲线是占空比的凹函数,因此极值搜索法通过控制占空比来提高风能的捕获效率,并通过改进提高了抗干扰能力和稳定性.实验结果证明了该方法的可行性.%In order to overcome the trouble brought by wind power generation system for maximum power,this paper puts forward a method based on extreme value method to capture the maximum power.The working principle of wind turbine and power characteristics are analyzed,the main factors affecting the power is discussed.Through the analysis of extremum search method on the basic theory and characteristics which combined with its working principle, come to a decision that power curve is concave function of duty cycle.Therefore,extreme value search method can control the duty cycle to improve the efficiency of wind capture, and improve anti-interference ability and stability .Through experiments, the final experimental curves obtained prove the feasibility of the method.

  14. Statistical changes in lakes in urbanizing watersheds and lake return frequencies adjusted for trend and initial stage utilizing generalized extreme value theory

    Science.gov (United States)

    Paynter, Shayne

    Many water resources throughout the world are demonstrating changes in historic water levels. Potential reasons for these changes include climate shifts, anthropogenic alterations or basin urbanization. The focus of this research was threefold: (1) to determine the extent of spatio-temporal changes in regional precipitation patterns, (2) to determine the statistical changes that occur in lakes with urbanizing watersheds, and (3) to develop accurate prediction of trends and lake level return frequencies. To investigate rainfall patterns regionally, appropriate distributions, either gamma or generalized extreme value (GEV), were fitted to variables at a number of rainfall gages utilizing maximum likelihood estimation. The spatial distribution of rainfall variables was found to be quite homogenous within the region in terms of an average annual expectation. Furthermore, the temporal distribution of rainfall variables was found to be stationary with only one gage evidencing a significant trend. In order to study statistical changes of lake water surface levels in urbanizing watersheds, serial changes in time series parameters, autocorrelation and variance were evaluated and a regression model to estimate weekly lake level fluctuations was developed. The following general conclusions about lakes in urbanizing watersheds were reached: (1) The statistical structure of lake level time series is systematically altered and is related to the extent of urbanization, (2) in the absence of other forcing mechanisms, autocorrelation and baseflow appear to decrease, and (3) the presence of wetlands adjacent to lakes can offset the reduction in baseflow. In regards to the third objective, the direction and magnitude of trends in flood and drought stages were estimated and both long-term and short-term flood and drought stage return frequencies were predicted utilizing the generalized extreme value (GEV) distribution with time and starting stage covariates. All of the lakes

  15. Prediction of Optimum pH of G/11 Xylanases and the Relationship between the Location of Amino Acid and Optimum pH Value%G/11木聚糖酶最适 pH 值的预测及其与氨基酸位置的关系

    Institute of Scientific and Technical Information of China (English)

    林源清; 张光亚

    2014-01-01

    把木聚糖酶全序列均分为 N 端,中间端(I 端)及 C 端3个部分,并分别以全序列及分段氨基酸的组成作为模型输入值.通过主成分分析(PCA)方法探讨全序列及分段氨基酸组成和最适 pH 值的相关性,运用均匀设计法分别优化支持向量机和 BP 神经网络运行参数.研究结果表明:支持向量机获得的预测模型优于神经网络,其中 RBF 支持向量机是最佳的模型.主成分分析结果显示:I 端主成分跟最适 pH 值相关性最高;相关系数 R 绝对值为0.68,得到的结果与支持向量机结果一致.%We divided the xylanase sequences into three equally segments named N-terminus,I-terminus and C-terminus. And then,we calculated the amino acid compositions of the whole sequences and the segmented sequences,respectively. The amino acid compositions were used as the input values of these models.The principal component analysis (PCA) method was utilized to analyze the relationship between the amino acid composition and the optimum pH.The uniform de-sign was used to optimize the running parameters of support vector machines (SVM)and neural network (BPNN),re-spectively.Our results showed the predicted model obtained by SVM was better than that of BPNN,and the SVM model based on RBF kernel was best.The results of PCA showed the correlation between principle component and optimum pH was best in the I-terminus with the R=-0.68,which coincided with the result of the SVM.

  16. Effect of Cu and Ni on Growth,Mineral Uptake,Photosynthesis and Enzyme Activities of Chlorella vulgaris at different pH Values

    Institute of Scientific and Technical Information of China (English)

    P.K.RAI; NirupamaMALLICK; 等

    1994-01-01

    A pH dependent reduction in growth,pigment,ATP content,O2 evolution,carbon fixation,photosynthetic electron transport system,nutrient uptake(No3- and NH4+) nitrate reductase,and ATPase activities and increase in K+-efflux of Chlorella vulgaris was noticed following supplementation of Cu and Ni to the culture medium.PSⅡ was found to be more sensitive to both pH and metals than PS I.Though.nitrate reductase(NR)was more sensitive to both pH and metals,the ATP ase was however,more sensitive to metals but less sensitive to acidic pH.Acid pH was found to inhibit the nutrinent(NO3-and NH4+) uptake and nitrate reductase in a non-competitive manner.The inhibition produced by the test metals alone was of non-competitive type for NO3- uptake,nitrate reductase and ATPase and competitive for NH4+ uptake.Acidity not only inhibited the metabolic variables directly but also through facilitated uptake of metals and increased membrane permeability.A very low sensitivity of ATPase to acidic pH seems to be responsible for the survival of algae in acid environment.

  17. Research on Step-wise Control pH Value in the First-step Fermentation Process of Vitamin C%维生素C一步发酵过程阶梯式控制pH值的研究

    Institute of Scientific and Technical Information of China (English)

    付海晨; 齐代鹏

    2011-01-01

    Currently change of the pH value was mainly adjusted by calcium carbonate during the first-step fermentation process of Vitamin C(referred to as VC).Through adding sodium carbonate,to step-wise control the pH value of the VC fermentation process.The results showed that pre-fermentation was controled the pH value at 6.0,post-fermentation pH value at 5.0 by adding the sodium carbonate,the fermentation period could be shortened further 33%.%目前维生素C(简称VC)第一步发酵过程中pH值的变化主要由CaCO3来调解。研究了Na2CO3代替CaCO3,并采用阶梯式控制发酵过程的pH值。结果表明:通过Na2CO3来控制发酵过程中pH值[前期控制pH值为6.0(8 h前),后期控制pH值为5.0],可以缩短一步发酵周期33%。

  18. Influence of pH Value of Emulsified Asphalt on CA Mortar Work Performance%乳化沥青pH值对CA砂浆工作性能的影响

    Institute of Scientific and Technical Information of China (English)

    刘宝举; 宁少英; 杨元霞; 陈欢

    2012-01-01

    基于乳化沥青pH值对ξ电位的影响,研究了乳化沥青pH值对CA砂浆流动度、可工作时间、分离度、含气量、表观密度及浆体体系pH值的影响.结果表明:乳化沥青pH值在2.5~9.5时,CA砂浆流动度处于稳定状态;pH<2.5,pH>9.5时,CA砂浆流动度均增加,且后者增加显著;pH=11.5时,其流动度达到最高;pH=9.5时,60 min后CA砂浆流动度经时损失最大,达到26.09%.pH=2.5时,CA砂浆表观密度随时间的延长逐渐减小;pH=9.5时,CA砂浆表观密度随时间的延长而增大.pH=1.5,9.5时,CA砂浆的分离度最小.乳化沥青pH值对CA砂浆浆体体系pH值的影响不大.为提高CA砂浆的综合性能,乳化沥青的合适pH值为1.5或9.5.%Influence of pH value of emulsified asphalt on work performance of CA mortar was studied by measuring the effect of pH on zeta potential. Results show that the pH of emulsified asphalt has great influence on the fluidity, working time, separating degree, air content and apparent density and pH of CA mortar, which results in the influence of pH of emulsified asphalt on zeta potential. When pH = 2. 5 -9. 5, the fluidity of CA mortar keeps in a stable level, while pH<2. 5, the fluidity increases, and it increases significantly when pH>9. 5, the fluidity reaches a maximum value when pH = ll. 5. The loss of fluidity with time reaches to 26. 09% when pH = 9. 5. The apparent density decreases with time when pH =2. 5, and it increases when pH = 9. 5. Separating degree has no effect on the symbols of the ζ potential, but it has influence on its absolute value. The bigger the absolute value, the smaller the separating degree and vice versa. When pH = l. 5 and 9. 5, the separating degree was small. pH of asphalt has a little influence on the pH of CA mortar. The appropriate pH of asphalt for CA mortar is 1. 5 or 9. 5.

  19. 基于极值理论的煤矿事故风险分析%Risk Analysis of Coal Mine Accidents Based on Extreme Value Theory

    Institute of Scientific and Technical Information of China (English)

    刘浪; 费明虎

    2012-01-01

    According to the statistics of monthly dead personnel data from coal mine accident in our recent ten years, we can draw a conclusion that, given different confidence level of mining accident, there is the maximum loss value of different risks, namely the big- gest potential accident death toll in each month based on the extreme value theory, which provides a theoretical guidance for the management of safety production in coal mine field.%运用极值理论,根据我国近十余年煤矿事故中每月死亡人员的统计数据,分别得出了在不同置信水平下,我国煤矿事故中的最大风险损失值,即未来事故中每月最大的潜在死亡人数,从而为我国开展煤矿安全生产管理工作提供理论指导。

  20. Effect of pH Value on the Desulfurization Process in Flue Gas Desulfurization%烟气脱硫中pH值对脱硫过程的影响

    Institute of Scientific and Technical Information of China (English)

    王振华

    2014-01-01

    Wet Limestone - gypsum flue gas desulfurization system (FGD system) is currently dominant in the domestic coal-fired power plant FGD system. FGD is designed to chemically remove sulfur dioxide in the flue gas leaving the flue gas will be purified. pH value as a measure of gypsum slurry pH, is an important technical parameters of the desulfurization process, at the same time as an environmental indicators relate with chemical reaction. Utilization of limestone, desulfurization efficiency and quality of gypsum slurry are closely related with the control of pH value. We usually control the pH value by controlling the mixing amount of limestone (CaCO3). Increasing the pH value can increase the amount of limestone, and vice versa reduction. On operation, the stability of pH value must be maintained. Increasing the pH value will increase the alkalinity of system and desulfurization efficiency, but the utilization of limestone will be reduced, and accelerate the formation of scale, ultimately affect the quality of gypsum. Reducing the pH value will increase the acidity of the system, improve the utilization of limestone, accelerate precipitation of gypsum crystals, but it will also accelerate the corrosion of the system, make the system is unstable, and the desulfurization efficiency will be greatly reduced. Therefore, the control of slurry pH value should seek the best value to meet the requirements under the premise of the desulfurization rate and generally the pH is controlled in the best range of 5.0-5.8.%湿法石灰石-石膏烟气脱硫系统(即FGD系统)目前在国内外燃煤电站FGD系统中占绝对优势。FGD的目的是用化学方法除去烟气中的二氧化硫而使烟气得以净化。pH值作为石膏浆液酸碱度的度量,是脱硫工序中一项重要的技术参数,同时可作为一项与化学反应相关的环境指标。石灰石利用率、脱硫效率和石膏浆液品质等与pH值的控制密切相关。通常我们

  1. Experimental simulation on migration and conversion of organophosphor by pH value in aquitard%pH值对有机磷在弱透水层中迁移转化的试验模拟

    Institute of Scientific and Technical Information of China (English)

    宋顶峰; 李红艳; 李建萍; 李绪谦; 罗艳春

    2011-01-01

    In order to study the effect of pH value on migration and conversion to organophosphor in permeable clay, permeation and pressure equipment were adopted to simulate the migration and conversion process of organophosphor permeating the aquitard in the polluted aquifer. It indicates that the migratory capacity of organophosphor in aquitard is weak, while the mineralization rate of organophosphor is between 93.5% and 99. 95% with different pH conditions. During pH value as 5.5 to 8. 5, the activity of acid phosphatase going up with pH value increases, while the ability of degradation and conversion becomes stronger, and the retardation for organophosphor in clay enhances along with pH value. When pH value is 5.5, the migration rate is 6. 5%. As the pH value reaches to 8. 5, the mineralization rate increases obviously with the migration rate less than 0. 05%, which hard for organophosphor permeate into the deep phreatic water and bring pollution.%为研究渗透水PH值对有机磷通过弱透水黏土层迁移转化的影响规律,采用黏性土层充压渗透装置模拟污染潜水中有机磷渗透通过弱透水层的迁移转化过程.研究发现,有机磷组分通过弱透水层的迁移能力总体较弱,不同PH值条件下有机磷的矿化率为93.5%~99.95%;在进水PH值为5.5~8.5时,进水PH值越高,土层中磷酸酶的活性也越高,降解转化有机磷的能力也越强;黏土对有机磷的阻滞能力也增强.进水PH值为5.5时,迁移率为6.5%;当PH达到8.5时,矿化率明显增加,迁移率<0.05%,使其不易渗入深层地下水引起污染.

  2. Clinical Psychology Ph.D. Program Admissions: Differential Values as a Function of Program Characteristics and the Implications of the Mentor-Model Approach

    Science.gov (United States)

    Metzger, Jesse A.

    2010-01-01

    The aims of this research were to 1) examine the qualities for which applicants are selected for entrance into clinical psychology Ph.D. programs, and 2) investigate the prevalence and impact of the mentor-model approach to admissions on multiple domains of programs and the field at large. Fifty Directors of Clinical Training (DCTs) provided data…

  3. Clinical Psychology Ph.D. Program Admissions: Differential Values as a Function of Program Characteristics and the Implications of the Mentor-Model Approach

    Science.gov (United States)

    Metzger, Jesse A.

    2010-01-01

    The aims of this research were to 1) examine the qualities for which applicants are selected for entrance into clinical psychology Ph.D. programs, and 2) investigate the prevalence and impact of the mentor-model approach to admissions on multiple domains of programs and the field at large. Fifty Directors of Clinical Training (DCTs) provided data…

  4. Birth asphyxia measured by the pH value of the umbilical cord blood may predict an increased risk of attention deficit hyperactivity disorder

    DEFF Research Database (Denmark)

    Mikkelsen, Susanne Hvolgaard; Olsen, Jørn; Bech, Bodil Hammer

    2017-01-01

    AIM: Although birth asphyxia is a major risk factor for neonatal and childhood morbidity and mortality, it has not been investigated much in relation to attention deficit hyperactivity disorder (ADHD). We examined whether birth asphyxia measured by the pH of the blood in the umbilical artery cord...

  5. pH值对羟丙基胍胶压裂液性能的影响%Effect of pH Value on Performance of Hydroxypropyl Guar Gum Fracturing Fluid

    Institute of Scientific and Technical Information of China (English)

    唐洪彪; 王世彬; 郭建春

    2016-01-01

    为了弄清压裂液的pH值在水力压裂施工不同阶段所起的作用,开展了pH值对羟丙基胍胶溶胀、交联、携砂、破胶性能的影响研究。结果表明,pH=7数10时,羟丙基胍胶在20 min内完全溶胀;pH=11数14时,羟丙基胍胶至少需要50 min才能完成溶胀。Ostwald-Dewaele方程能描述冻胶黏度随剪切速率变化关系,pH=7数12时的稠度系数较大,大于16744 mPa·sn;pH=13数14时的稠度系数明显减小,小于3130 mPa·sn。静态沉降实验表明,pH=9数12时的静态沉降速度较小,为1.31数5.94 mm/h;pH=7、8、13时的静态沉降速度较大,大于10.64 mm/h;pH=14时,支撑剂20 s内完成沉降。破胶实验研究发现,冻胶在pH=7数10时的破胶速度大于pH=1数14时的破胶速度;pH=7数12时,残渣含量较小,为400 mg/L左右。满足各施工阶段的pH值范围为9数10。图5表2参12 lnha=lnK+(n-1)lng%pH was an important factor affecting the performance of hydraulic fracturing. The effect of pH on the swelling performance of hydroxypropyl guar gum,crosslinking properties,proppant settlement,guar gum degradation was studied. The results showed that,at the pH value of 7—10,the swelling time of hydroxypropyl guar gum was less than 20 min,while at the pH value of 11—14 ,the swelling time was larger than 50 min ,the swelling rate at the pH value of 7—10 was relatively higher than that at the pH value of 11 —14. The relationship between gel viscosity and shear rate could be described by the Ostwald-Dewaele equation ,and at the pH value of 7—12 ,the consistency coefficient of hydroxypropyl guar gum solution was larger than 16744 mPa·sn,while the consistency coefficient at the pH value of pH 13—14 was less than 3130 mPa·sn. The proppant settlement experiments showed that,at the pH value of 9—12,the settling rate of proppant was relatively low,being of 1.31—5.94 mm/h;at the pH value of 7,8,13,the settling rate increased and the value

  6. Characterization of the Tail of the Distribution of Earthquake Magnitudes by Combining the GEV and GPD Descriptions of Extreme Value Theory

    Science.gov (United States)

    Pisarenko, V. F.; Sornette, A.; Sornette, D.; Rodkin, M. V.

    2014-08-01

    The present work is a continuation and improvement of the method suggested in P isarenko et al. (Pure Appl Geophys 165:1-42, 2008) for the statistical estimation of the tail of the distribution of earthquake sizes. The chief innovation is to combine the two main limit theorems of Extreme Value Theory (EVT) that allow us to derive the distribution of T-maxima (maximum magnitude occurring in sequential time intervals of duration T) for arbitrary T. This distribution enables one to derive any desired statistical characteristic of the future T-maximum. We propose a method for the estimation of the unknown parameters involved in the two limit theorems corresponding to the Generalized Extreme Value distribution (GEV) and to the Generalized Pareto Distribution (GPD). We establish the direct relations between the parameters of these distributions, which permit to evaluate the distribution of the T-maxima for arbitrary T. The duality between the GEV and GPD provides a new way to check the consistency of the estimation of the tail characteristics of the distribution of earthquake magnitudes for earthquake occurring over an arbitrary time interval. We develop several procedures and check points to decrease the scatter of the estimates and to verify their consistency. We test our full procedure on the global Harvard catalog (1977-2006) and on the Fennoscandia catalog (1900-2005). For the global catalog, we obtain the following estimates: = 9.53 ± 0.52 and = 9.21 ± 0.20. For Fennoscandia, we obtain = 5.76 ± 0.165 and = 5.44 ± 0.073. The estimates of all related parameters for the GEV and GPD, including the most important form parameter, are also provided. We demonstrate again the absence of robustness of the generally accepted parameter characterizing the tail of the magnitude-frequency law, the maximum possible magnitude M max, and study the more stable parameter Q T ( q), defined as the q-quantile of the distribution of T-maxima on a future interval of duration T.

  7. Relationship of Gastric pH Value and Feeding Intolerance in Very Low Birth Weight Infants (VLB-WI)%极低出生体重儿胃液 pH 值与喂养不耐受的相关性研究

    Institute of Scientific and Technical Information of China (English)

    郝群英

    2016-01-01

    Objective]To explore the relationship of gastric pH value and feeding intolerance in very low birth weight infant (VLBWI).[Method]80 cases of very low birth weight children in our hospital from January 2010 to December 2014 also in the neonatal intensive care unit were chosen for our study.Using the feeding intolerance di-agnostic criteria,the children were selected and divided into two groups.Group 1 had no feeding intolerance (36 cases)and Group 2 had feeding in tolerance (44 cases).The two groups of children were observed in respect to gastric pH value,feeding conditions (feeding time,the amount of intake and gastric residue),and feeding toler-ance (bloating times,frequency of vomiting,abnormal stool frequency).[Results]Group 1 had a feeding intoler-ance rate of 100%,significantly higher than the 8.33% rate in Group 2 (P <0.05),while the average gastric pH value was also higher in Group 1 than Group 2 (P <0.05).The occurrence of VLBWI feeding intolerance and gas-tric pH value were positively correlated r =0.77,P =0.00.[Conclusion]Gastric pH value in very low weight new-borns with feeding intolerance showed significant correlation with the gastric pH levels in the infants.It is worthy of effective monitoring to help clinicians and nurses to understand neonatal gastrointestinal function and promote neonatal rehabilitation reference.%【目的】探讨极低出生体重儿(VLBWI)胃液 pH 值与喂养不耐受的关系。【方法】选取2010年1月至2014年12月本院新生儿重症监护室(NICU)收治的 VLBWI 80例。参照喂养不耐受诊断标准,将入选患儿分为喂养耐受组36例,喂养不耐受组44例。比较两组患儿的胃液 pH 值、喂养耐受情况(胃残留量、腹胀、呕吐、大便异常)。【结果】喂养不耐受组喂养不耐受发生率为100%,高于喂养耐受组的8.33%(P <0.05),同时其平均胃液 pH 值高于喂养不耐受组(P <0.05);VLBWI 胃液 pH 值与胃残留量呈正相关,r =0.77,P =0.00

  8. 右旋糖酐40葡萄糖注射液 pH 值与5-羟甲基糠醛、糠醛含量的相关性分析%Correlation Analysis of Furfural, 5-hydroxymethylfurfural Content and pH Value of Dextran 40 and Glucose Injection

    Institute of Scientific and Technical Information of China (English)

    郭欢迎; 耿庆光; 王嫦鹤

    2015-01-01

    Objective To analyze the correlation of furfural, 5-hydroxymethylfurfural (5-HMF) content and pH value of dextran 40 and glucose injection, and to provide reasonable suggestions for the production, transportation and use. Methods High performance liquid chromatography method was used to determine the content of 5- HMF and furfural of 90 batches of dextran 40 and glucose Injection. The pH value of the solution was determined by acidometer. Correlation of furfural, 5-HMF content and pH value was analyzed by SPASS 17.0. The destructive tests were carried out to verify the conclusion. Results There is a negative correlation between the value of pH and content of 5- HMF, and the content of furfural was positively correlated with 5- HMF. Destructive test results show that, the decrease of pH value will lead to the generation of 5- HMF and furfural. Conclusion Through the strict control of pH value, the stability of dextran 40 and glucose injection can be increased. And the increase 5- HMF and furfural content of the preparation could be suppressed too.%目的:对右旋糖酐40葡萄糖注射液的 pH 值与5-羟甲基糠醛、糠醛含量进行相关性分析,为其生产、运输和使用提供合理化建议。方法采用高效液相色谱法对所有90批右旋糖酐40葡萄糖注射液中的5-羟甲基糠醛、糠醛进行测定,同时采用酸度计测定溶液的 pH 值,并用 SPASS 17.0对测定结果的 pH 值与5-羟甲基糠醛、糠醛进行相关性分析,并采用破坏性试验对结论进行验证。结果右旋糖酐40葡萄糖注射液的 pH 值与5-羟甲基糠醛的含量负相关,5-羟甲基糠醛的含量与糠醛的含量呈正相关。破坏性试验结果证明,pH 值的降低会导致5-羟甲基糠醛和糠醛的生成。结论通过严格控制该制剂的 pH 值,可以增加右旋糖酐40葡萄糖注射液的稳定性,抑制制剂中5-羟甲基糠醛和糠醛含量的增加。

  9. Statistical Inference for Binomial-generalized Pareto Compound Extreme Value Distribution Model%二项-广义Pareto复合极值分布模型的统计推断

    Institute of Scientific and Technical Information of China (English)

    张香云; 程维虎

    2012-01-01

    Extreme value theory is mainly the study on extreme events of small probability & major impact. At present, the compound extreme value distribution has been widely used in hydrology, meteorology, earthquake, insurance, finance and other fields. In this paper, we establish binomial-generalized Pareto compound extreme value distribution model based on extreme value type theorem and PBDH theorem, derive parameter estimation of the established compound model by probability weighted moments, get critical values of Kolmogorov-Smirnov test statistic.%极值理论主要研究小概率、大影响的极端事件.当前,复合极值分布已经广泛应用于水文、气象、地震、保险、金融等领域.本文以极值类型定理和PBDH定理为理论依据,构建了二项-广义Pareto复合极值分布模型;使用概率加权矩方法,对所建立的复合模型推导参数估计式;利用计算机模拟,得到了Kolmogorov-Smirnov(简称KS)检验统计量的临界值.

  10. Effect of pH value on adiabatic decomposition characteristics of hydrogen peroxide%pH值对双氧水绝热分解特性的影响

    Institute of Scientific and Technical Information of China (English)

    孙峰; 谢传欣; 张帆; 金满平; 王振刚

    2012-01-01

    In order to study the influence of pH value on the thermal hazard of hydrogen peroxide, VSP2 (Vent Size Package 2) was used to analyze the thermal behavior of hydrogen peroxide (mass fraction 27. 5%) with different pH values of 1.8, 4, 5,6,7,8 under adiabatic condition. The adiabatic decomposition characteristics of the hydrogen peroxide with different pH values were recorded. The thermal decomposition kinetics of the decomposition reaction concerned was obtained. The time to the maximum reaction rate at 30 ℃ under adiabatic condition was also worked out from the kinetics data. The results show that as the pH value of hydrogen peroxide increasing, the onset exothermic temperature decreases, and the time to the maximum reaction rate under adiabatic conditions gets shorter, so the risk probability of thermal runaway significantly increases. When hydrogen peroxide is stored in the industrial conditions, there is a certain risk when pH value is 6, and thermal runaway is almost inevitable when pH value is more than 7.%为了考察pH值对双氧水热危害的影响,利用VSP2绝热量热仪对pH值分别为1.8,4,5,6,7及8的质量分数为27.5%的双氧水进行了绝热条件下测试,得到了不同pH值双氧水的绝热分解特征,求得了双氧水的分解动力学,并计算得到双氧水在起始温度为30℃时绝热条件下到达最大反应速率所需时间.结果表明:当双氧水pH值增加时,起始放热温度降低,到达最大反应速率所需时间缩短,热失控危险性明显增加,双氧水在工业条件下存储时,当pH值增加至6时就有一定危险性,当pH值增加至7以上时热失控几乎不可避免.

  11. A measure of endosomal pH by flow cytometry in Dictyostelium

    Directory of Open Access Journals (Sweden)

    Cosson Pierre

    2009-01-01

    Full Text Available Abstract Background Dictyostelium amoebae are frequently used to study the organization and function of the endocytic pathway, and specific protocols are essential to measure the dynamics of endocytic compartments and their internal pH. Findings We have revisited these classical protocols to measure more accurately endosomal pH, making use of a fluorescent probe (Oregon green more adequate for very acidic pH values. This pH-sensitive probe was combined with a pH-insensitive marker, in order to visualize simultaneously endosome dynamics and pH changes. Finally, a flow cytometer was used to measure endosomal pH in individual cells. Conclusion Using these simple protocols the endosomal pH of endocytic compartments can be assessed accurately, revealing the extreme acidity of Dictyostelium lysosomes (pH

  12. Immobilized pH gradients (IPG) simulator--an additional step in pH gradient engineering: I. Linear pH gradients.

    Science.gov (United States)

    Tonani, C; Righetti, P G

    1991-12-01

    A new computer program, called immobilized pH gradients (IPG) simulator, is proposed for calculating and optimizing any recipe for use in isoelectric focusing in immobilized pH gradients. Unlike our previous monoprotic electrolyte gradient simulation (MGS) and polyelectrolyte gradient simulation (PGS) programs, based on minimizing CV(beta), the present program has a target function the minimization of the quadratic moment around zero of the residuals (mu 2). With this algorithm it is possible to formulate IPG recipes which have deviations from linearity well below 1% of the given pH interval (a limit set with the previous MGS and PGS programs), in fact, as small as 0.1-0.2% (in pH units). The new simulator performs 2-3 times better than the previous ones in the pH 4-10 range, and is absolutely necessary when working outside this range, at extreme pH values, where CV(beta) cannot work against the buffering power of bulk water, thus generating pH recipes with huge deviations from linearity. In the latter cases, mu 2 performs 10 times better than CV(beta). When utilizing strong titrants for extended pH intervals, the "all or none" rule has been discovered: such titrants should always be used in tandem, since omission of one of the two at either the acidic or basic extremes produces strongly distorted pH profiles. Our new, most powerful simulator also contains equations for creating nonlinear gradients, notably: concave and convex exponentials and sigmoidal (see the companion paper: Righetti, P. G. and Tonani, C., Electrophoresis 1991, 12, 1021-1027).

  13. 近30年川中丘陵县域表层土壤 pH 值时空变化分析--以四川仁寿县为例%Temporal and Spatial Variation of Topsoil pH Value in Hilly Area of Middle Sichuan Basin during 1981-2012:A Case Study in Renshou County,Sichuan

    Institute of Scientific and Technical Information of China (English)

    李珊; 肖怡; 李启权; 张维; 罗由林; 蒋欣烨; 张浩

    2015-01-01

    【目的】研究1981~2012年仁寿县表层土壤 pH 值时空变化特征。【方法】以1980年第二次土壤普查资料和2010年实地采样数据为基础,应用 GIS 技术和地统计学等研究方法分析研究区表层土壤 pH 值的时空变化及其在不同土壤类型、成土母质和土地利用方式下的变化特征。【结果】1981~2012年间研究区表层土壤 pH 值的空间分布格局基本一致,以东北和西南高,西北和东南低。土壤 pH 值由7.10下降到6.80,整体表现出酸化趋势,酸化程度由中部向西北和东南增强。其中以灌口组泥砂岩、自流井组泥灰岩、第四系老冲积冰水沉积物及须家河组砂岩发育形成的土壤 pH 值下降幅度最大,在9.69%~12.65%之间;各土壤类型 pH 的下降幅度与其初始值呈负相关,表现为黄壤(12.30%)>水稻土(4.46%)>紫色土(2.95%);不同土地利用方式土壤 pH 的下降幅度以园地和水旱轮作最大,分别下降了0.50和0.66个单位。半方差分析表明,土壤 pH 值的变程由65.9 km 缩短至52.7 km,块金值与基台值的比值由29.1%增加到30.1%,随机性因素使结构性因素的作用减弱,空间自相关程度和范围降低。影响因素的显著性分析表明,成土母质和土壤类型对1981年和2012年土壤 pH 值均有极显著影响(P <0.01),土地利用方式的作用由显著(P <0.05)变为极显著(P <0.01)。【结论】近30年来研究区土壤呈酸化趋势,表层土壤 pH值时空变异受成土母质和土壤类型等结构性因素及土地利用方式等随机性因素的影响,且随机性因素对研究区表层土壤 pH 值时空变异的影响在增强。%Objective]The aim of this paper was to reveal the temporal and spatial variation of topsoil pH value in Renshou county of Sichuan during 1981 -2012.[Method]Based on the data of the second national

  14. Characterization of Cu ( Ⅱ ) Binding with Rabbit Liver Metallothionein under Various pH Values Conditions%不同pH值条件下兔肝金属硫蛋白与铜(Ⅱ)结合的研究

    Institute of Scientific and Technical Information of China (English)

    粱淑轩; 艾丹丹; 孙汉文

    2011-01-01

    目的 研究不同pH值条件下兔肝金属硫蛋白(MT)与铜(Ⅱ)结合情况.方法 向2ml(pH值为3,4,5,6,7)的兔肝锌-金属硫蛋白溶液加入9.2×10-4 mol/L硫酸铜溶液0.2 ml.在200~300 nm波长下测定相应pH值Zn-MT溶液及其加入硫酸铜后与铜(Ⅱ)结合的紫外吸收情况.采用半透膜透析的方法除去过量金属离子,并采用电感耦合等离子体质谱( ICP-MS)法测定金属硫蛋白与铜(Ⅱ)的结合量.结果在相同的实验条件下,与金属硫蛋白结合的铜(H)含量随着pH值的升高而增加.透析24 h后,与金属硫蛋白结合的铜(Ⅱ)含量随着pH值升高呈现先下降后升高的趋势;且当pH=5时,与金属硫蛋白结合的铜(Ⅱ)含量最低.结论 在pH=5时,金属硫蛋白释放质子,不利于铜与金属硫蛋白的结合,铜与金属硫蛋白的结合能力较弱.由于组成金属硫蛋白的α-、β-结构域的差异,不同pH值时锌和铜与金属硫蛋白的结合位点不同,使得其与金属的结合能力存在差异.在pH值为3,4时,锌从金属硫蛋白中脱落,铜的结合量增加.%Objective To study the impact of pH value on the binding of Cu (Ⅱ) with rabbit liver metallothionein(MT). Methods 0.2 ml 9.2×10-4 mol/L CuSO4 solution was added to 2 ml of rabbit liver zinc-metallothionein solution at pH values of 3,4,5,6 and 7 respectively. UV absorption spectrogram of Zn-MT solution and Cu( Ⅱ) binding Zn-MT solution were scaned at 200-300 nm. Copper ( Ⅱ) binding with metallothionein was determined by inductively coupled plasma mass spectrometry (ICP-MS) method after removing the excess Cu2+ by semi-permeable membrane. Results The levels of copper( Ⅱ) binding with metallothionein increased with pH value increasing. Metallothionein binding copper (Ⅱ) content with the pH value declined at first, then increased, and copper (Ⅱ) content reached the lowest value at pH value of 5. Conclusion It is not conducive to copper binding metallothionein and the ability of

  15. Incidence of spontaneous bacterial peritonitis in patients with ascites. Diagnostic value of white blood cell count and pH measurement in ascitic fluid

    DEFF Research Database (Denmark)

    Storgaard, J S; Svendsen, Jesper Hastrup; Hegnhøj, J

    1991-01-01

    During a 21-month period, 65 consecutive patients admitted with ascites were included in a prospective study of the incidence of spontaneous bacterial peritonitis, and paracentesis was performed on admission. The ascitic fluid was cultured, ascitic leucocytes were counted and pH was measured....... Bacterial growth was found in five patients with chronic liver disease, who were diagnosed as having spontaneous bacterial peritonitis (SBP), since no intra-abdominal focus could be demonstrated. Thus, the incidence of SBP in this material was 7.7% (95% confidence limits: 2.5-17%). SBP was caused...

  16. Effects of pH value of reaction solution on structure and electrochemical performance of calcium-containing active material of secondary zinc electrodes

    Institute of Scientific and Technical Information of China (English)

    陈华; 王建明; 郑奕; 张鉴清; 曹楚南

    2004-01-01

    The calcium-containing active material of secondary alkaline zinc electrodes was prepared by a chemical coprecipitation method and characterized by scanning electron microscopy(SEM) and X-ray diffractometry(XRD).Their electrochemical performance was tested by the Galvanstatic charge-discharge method. The experimental results show that the sample synthesized at pH = 11.15 has a typical calcium zincate crystal. The zinc electrode using this sample as active material shows higher discharge capacity, more negative discharge plateau potential and longer cycle lifetime.

  17. Effects of applying different pH values on mung bean seed germination and seedlings growth%pH值对绿豆种子萌发和幼苗生长的影响

    Institute of Scientific and Technical Information of China (English)

    于秋良; 杨志贤; 李忠芳; 卢伟琳; 何子龙; 岑美婷; 覃娟清; 梁丽清; 李稳

    2012-01-01

    This research investigated the effects of applying different pH values and determining the pH soaking time on mung bean seed germination and seedlings growth in order to provide basis for reducing soil acidity stress by scientifically raising seedlings in Southern China bean planting aren. [Method ]The experiment was designed with 5 different degrees of pH values and 2 soaking times. The seed germination and seedling growth of mung bean were observed. [ResultjThe results showed that the germination speed was the fastest out of all treatments when the pH level was 7.5; under this pH level, the most numerous seedling germination was also observed. Two days after the seeds were soaked in pH 7.5 solutions for 6 and 12 hrs, the germination rate was 87.5% and 92.5%, respectively. On the other hand, four days after seeding, the tallest seedling plant height were measured after the seeds were soaked for 6 and 12 hrs under the pH solution of 7.5 and 7.0, respectively. For all seeds soaked for 6 and 12 hrs under pH level 6.5 and pH level 7.0, respectively, their seedlings showed the highest fresh weight, while those soaked in pH level 8.0 showed the heaviest dry seedling weight. [Conclusion]The optimal pH value for soaking mung bean seeds should be between 7.0-7.5 to achieve the best mung bean germination and seedling growth in Hezhou districts of Cuangxi.%[目的]研究不同pH值溶液及其不同浸泡时间对绿豆种子萌发和幼苗生长的影响,为在南方地区通过科学育苗减少土壤酸胁迫提供科学依据.[方法]用pH值6.0~8.0溶液分别浸泡绿豆种子6、12 h,观察绿豆种子萌芽及幼苗生长状况.[结果]当溶液pH值为7.5时,绿豆种子萌发速度最快、数量最多,2d后浸种6、12h的发芽率分别为87.5%和92.5%;浸种6、12h,播种4d后分别以pH值7.5和7.0处理的幼苗株高最高.浸种6、12h时,分别以pH值6.5、7.0处理的绿豆幼苗鲜重最高,而均以pH 8.0处理的幼苗干重最高.[结论]在广

  18. 50Hz工频磁场暴露对成年男性精子活力参数和精液酸碱度的影响%The effects of extremely low frequency electromagnetic field exposure on the pH of the adult male semen and the motoricity parameters of spermatozoa in vitro

    Institute of Scientific and Technical Information of China (English)

    徐向荣; 林胡; 张晓鑫; 李静怡; 章玮; 孙文均; 潘永苗

    2012-01-01

    目的 研究50 Hz极低频磁场暴露对成年男性精子活力、活动力参数和精液酸碱度的影响.方法 将成年健康男性新鲜精液标本分别暴露于0.4 mT、50 Hz正弦磁场中15、30、60 min,采用WUY-9000型伟力彩色精子质量检测系统动态记录精子活力、活动力参数并测定精液酸碱度.结果 新鲜精液标本暴露于50 Hz磁场中15 min,可使精子活力(a+b级精子)和精子活动率(a+b+c级精子)均呈抑制状态,与平行对照组相比,差异有统计学意义(P<0.01);暴露30 min,两组间精子活力和精子活动率差异无统计学意义(P>0.05);暴露60 min后,精子活力和活动率又呈抑制状态,与平行对照组相比,差异有统计学意义(P<0.01,P<0.05).然而,相同参数的磁场暴露15、30、60 min,对精液酸碱度无明显影响.结论 暴露于0.4 mT、50 Hz的正弦磁场中不会影响男性精液的酸碱度,但可明显抑制精子的活力和活动率.%Objective To study the effects of 50-Hz extremely low frequency electromagnetic field (ELFEMF) exposure on the pH of the adult male semen and the motoricity and motoricity parameters of spermatozoa.Methods Healthy adult male fresh semen was exposed to a 50-Hz EMF at 0.4 mT for 15,30 and 60 min,respectively.The pH value of the semen,the motoricity and motoricity parameter of spermatozoa were detected and recorded in real time using the WIJY-9000 pattern chromatic color spermatozoa quality detection system.Results Compared with parallel control group,the exposure of adult male fresh semen to a 50-Hz EMF at 0.4 mT for 15 min or 60 min could decrease significantly the motoricity (spermatozoa with a+b lever) and the activity ratio (spermatozoa with a+b+c lever) (P<0.01).However,there were no significant differences of motoricity and the activity ratio between exposure group and control group (P>0.05),and after exposure to a 50-Hz.EMF for 30 min the motoricity and the activity ratio of exposure group were

  19. Influence of different acids for adjusting the dyebath ph value on the dyeability of polyester knitwear dyed with disperse yellow 23

    Directory of Open Access Journals (Sweden)

    Miljković Milena N.

    2011-01-01

    Full Text Available In this paper the influence of the formic and oxalic acids, as substances for dyebath pH adjusting, on the dyeability of polyester fabric dyed with disperse dye Disperse Yellow 23 was examined. The polyester undyed knitwear samples were dyed in baths containing the acids under the same dyeing conditions. Color differences of the samples were assessed using the reflectiometry technique and expressed in terms of CIELcoordinates. The influence of the tested acids on the surface structure of dyed polyester fibers was examined using the scanning electron microscopy (SEM. It was found that the differences in obtained dyeabilities, in the presence of both formic and oxalic acid, are acceptable according to both M&S 83A and CMC (2:1 standards which was not the case with acetic acid. Therefore, acetic acid can be replaced with either formic or oxalic acid as substances for dyebath pH adjusting in the dyeing process described in this paper. SEM micrographs showed small differences in the surface structure of dyed fibers, as well as differences in the shape of undyed samples’ reflectance curves in presence of the acids. Since all of the color differences were quite small, it can be concluded that the influence of formic and oxalic acids on the polyester knitwear dyeability is not significantly different than that of acetic acid.

  20. 天山东部冰芯pH值和电导率的大气环境空间差异%The pH value and electrical conductivity of atmospheric environment from ice cores in the Tianshan Mountains

    Institute of Scientific and Technical Information of China (English)

    董志文; 张明军; 李忠勤; 王飞腾; 王文彬

    2009-01-01

    Electrical Conductivity Measurement (ECM) from ice core is a representative index for atmospheric environmental change. The pH value and ECM from three shallow ice cores (each 3.85 m, 231 ice samples total) on Glacier No.1 at the headwater of Urumqi River, Gla-cier No.48 in Kuitun area, and Miaoergou Glacier in Hami area in the eastern Tianshan Mountains, western China, were measured and analyzed for atmospheric environment re-cords research. Ice core record shows that the changing trend of pH and ECM in three sites in recent years is different: ECM in Kuitun increases with the ice depth change, but ECM in Hami and Urumqi Glacier No.1 ice cores show a decreasing trend. Average ECM value in Hami is much larger than other two sites, just as the dust concentration and ions concentra-tion are also very high in this site. ECM records in all three sites are mainly affected by aerosol mineral dust of Central Asia, and correlative coefficients of ECM and mineral ions such as Ca2+, Mg2+, Na+ are all significantly high. The pH value and ECM are also significantly high correlative coefficients in the eastern Tianshan Mountains. Comparison between the eastern Tianshan Mountains and other sites in western China, and Polar Regions, shows that the difference of ECM can very well reflect the spatial difference of worldwide atmospheric environment.

  1. 糖厂澄清工段pH值测量电路设计与实现%Design and implementation of pH value measurement circuit in clarification workshop section in sugar industry

    Institute of Scientific and Technical Information of China (English)

    宋春宁; 宋云鹏; 林小峰; 宋绍剑; 李荣军

    2012-01-01

    Aiming at the impedance matching and electromagnetic interference problems in pH value measuring in the complex conditions in sugar factory,for the first time,HCNR201 optocoupler isolation is applied to INA116 preamplification circuit, the pH value measuring circuit is worked out. The experimental result shows that this circuit can not only solve the impedance matching and electromagnetic interference problems,but also collect the pH value quickly and precisely.%针对糖厂复杂工作环境中pH玻璃电极测量存在的阻抗匹配和工业现场电磁信号干扰问题,率先把线性光耦HCNR201运用到INA116前置放大电路中,设计出pH值测量电路.实验结果表明:该电路可以解决阻抗匹配和电磁干扰2个问题,并能快速准确采集蔗汁pH值.

  2. Influence of pH Value on the Determination of Hexavalent Chromium by Diphenylcarbazide Spectrophotometry%pH值对二苯碳酰二肼分光光度法测定六价铬的影响

    Institute of Scientific and Technical Information of China (English)

    王海云; 李敏锐; 廖涛; 谭飞帆; 邓杰

    2012-01-01

    Based on the 1,5 -diphenylcarbazide spectrophotometry, we researched on the influence of pH value on the determination of hexavalent chromium. By adding different amounts of acid into two water samples with different volumes and concentrations, we measured the absorbances of the solutions so as to determine the hexavalent chromium. Through analysis by EXCEL on the measured data, we found that the absorbance reduced with the decrease of pH value. In the presence of high acidity, which means small pH value, the measured hexavalent chromium was smaller than the original value before adding acid. Therefore, the variation of pH value had an impact on the measurement of hexavalent chromium. Moreover, we employed the gray system model GM( 1,1) to process the experimental data, and derived a linear equation for the absorbance under different acidities. Through t test and F test, no significant difference was found between calculated absorbance and measured absorbance. This research is helpful to quantitatively looking into the influence of pH value on hexavalent chromium determination.%为获得不同pH值对测定六价铬(Cr(Ⅵ))的影响,以标准分析方法二苯碳酰二肼(C13H14N4O)分光光度法为基础,选用2种体积浓度的水样,分别加入不同的酸量,测定吸光度.经EXCEL软件对实测数据分析,得出加酸量与吸光度具有紧密的相关性,发现吸光度随着溶液pH值的减小而减小,酸度偏大,测定的实际结果比真实值小,pH值的不同对Cr(Ⅵ)测定结果具有影响.采用灰色系统模型GM(1,1)对实验数据进行处理,推导出不同酸度下的吸光度直线方程式.经t检验和F检验证明,计算出的吸光度值与测定值不存在显著性差异,可帮助定量掌握不同酸度条件下对测定Cr(Ⅵ)产生影响具有一定的作用.

  3. Effect of pH value on VFA concentration and composition during anaerobic fermentation of kitchen waste%pH值对餐厨垃圾厌氧发酵产挥发性脂肪酸的影响

    Institute of Scientific and Technical Information of China (English)

    张玉静; 蒋建国; 王佳明

    2013-01-01

    Under mesophilic conditions(35 °C), batch experiments were carried out to determine the effect of pH value on volatile fatty acid(VFA) concentration and composition during anaerobic acidogenesis of kitchen wastes. The pH value was uncontrolled in one reactor and controlled at 5.0,6.0,7.0 in other reactors. The results showed that the greatest degree of hydrolysis and acidogenesis was obtained and more organic acid was produced when the pH value was controlled at 6.0. When the pH value was controlled at 6.0, the maximum VFA concentration and yields of 40.89g/L and 0.328gVFA/gVS was obtained in the 68th hour, and was 8 times of that when the pH value was not controlled. The product composition in the acid reactor strongly depended on the pH value. The pH value of the uncontrolled reactor dropped from 6.6 to 3.8 quickly within 24 hours. Ethanol was the main product, accounted for 59.8% of total end products. So the typical ethanol-type fermentation occurred when the pH value was not controlled. It was butyric acid-type fermentation when the pH value was controlled at 5.0, 6.0 and 7.0. Acetic acid was main product at pH 5.0, butyric acid was dominant at pH 6.0, proportion of acetic acid and butyric acid was similar to each other at pH 7.0. The optimum pH value of hydrolysis and acidogenesis of kitchen wastes was 6.0.%通过间歇实验研究了中温条件下pH值对餐厨垃圾厌氧发酵产挥发性脂肪酸(VFA)的影响.考察了pH值为5.0、6.0、7.0及不控制pH值下的有机酸浓度及组成情况.结果表明,当控制反应器中pH值为6.0时,餐厨垃圾水解酸化效果最好,比其他pH值条件下产生更多的有机酸.pH值为6.0时,VFA浓度与单位VS产酸量在第68h达到最大值分别为40.89g/L和0.328gVFA/gVS,是不控制pH值时的8倍.pH值对发酵产物组成影响显著.不控制pH值时,反应器内的pH值在241h内由6.6迅速下降到3.8,乙醇为主要的发酵产物,占59.8%,表现为典型的乙醇型

  4. Valuation of Indonesian catastrophic earthquake bonds with generalized extreme value (GEV) distribution and Cox-Ingersoll-Ross (CIR) interest rate model

    Energy Technology Data Exchange (ETDEWEB)

    Gunardi,; Setiawan, Ezra Putranda [Mathematics Department, Gadjah Mada University (Indonesia)

    2015-12-22

    Indonesia is a country with high risk of earthquake, because of its position in the border of earth’s tectonic plate. An earthquake could raise very high amount of damage, loss, and other economic impacts. So, Indonesia needs a mechanism for transferring the risk of earthquake from the government or the (reinsurance) company, as it could collect enough money for implementing the rehabilitation and reconstruction program. One of the mechanisms is by issuing catastrophe bond, ‘act-of-God bond’, or simply CAT bond. A catastrophe bond issued by a special-purpose-vehicle (SPV) company, and then sold to the investor. The revenue from this transaction is joined with the money (premium) from the sponsor company and then invested in other product. If a catastrophe happened before the time-of-maturity, cash flow from the SPV to the investor will discounted or stopped, and the cash flow is paid to the sponsor company to compensate their loss because of this catastrophe event. When we consider the earthquake only, the amount of discounted cash flow could determine based on the earthquake’s magnitude. A case study with Indonesian earthquake magnitude data show that the probability of maximum magnitude can model by generalized extreme value (GEV) distribution. In pricing this catastrophe bond, we assumed stochastic interest rate that following the Cox-Ingersoll-Ross (CIR) interest rate model. We develop formulas for pricing three types of catastrophe bond, namely zero coupon bonds, ‘coupon only at risk’ bond, and ‘principal and coupon at risk’ bond. Relationship between price of the catastrophe bond and CIR model’s parameter, GEV’s parameter, percentage of coupon, and discounted cash flow rule then explained via Monte Carlo simulation.

  5. Valuation of Indonesian catastrophic earthquake bonds with generalized extreme value (GEV) distribution and Cox-Ingersoll-Ross (CIR) interest rate model

    Science.gov (United States)

    Gunardi, Setiawan, Ezra Putranda

    2015-12-01

    Indonesia is a country with high risk of earthquake, because of its position in the border of earth's tectonic plate. An earthquake could raise very high amount of damage, loss, and other economic impacts. So, Indonesia needs a mechanism for transferring the risk of earthquake from the government or the (reinsurance) company, as it could collect enough money for implementing the rehabilitation and reconstruction program. One of the mechanisms is by issuing catastrophe bond, `act-of-God bond', or simply CAT bond. A catastrophe bond issued by a special-purpose-vehicle (SPV) company, and then sold to the investor. The revenue from this transaction is joined with the money (premium) from the sponsor company and then invested in other product. If a catastrophe happened before the time-of-maturity, cash flow from the SPV to the investor will discounted or stopped, and the cash flow is paid to the sponsor company to compensate their loss because of this catastrophe event. When we consider the earthquake only, the amount of discounted cash flow could determine based on the earthquake's magnitude. A case study with Indonesian earthquake magnitude data show that the probability of maximum magnitude can model by generalized extreme value (GEV) distribution. In pricing this catastrophe bond, we assumed stochastic interest rate that following the Cox-Ingersoll-Ross (CIR) interest rate model. We develop formulas for pricing three types of catastrophe bond, namely zero coupon bonds, `coupon only at risk' bond, and `principal and coupon at risk' bond. Relationship between price of the catastrophe bond and CIR model's parameter, GEV's parameter, percentage of coupon, and discounted cash flow rule then explained via Monte Carlo simulation.

  6. Biosorption of U(VI) by the green algae Chlorella vulgaris in dependence of pH value and cell activity

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, M., E-mail: M.Vogel@fzd.de; Guenther, A.; Rossberg, A.; Li, B.; Bernhard, G.; Raff, J.

    2010-12-15

    Biosorption of uranium(VI) by the green alga Chlorella vulgaris was studied at varying uranium concentrations from 5 {mu}M to 1 mM, and in the environmentally relevant pH range of 4.4 to 7.0. Living cells bind in a 0.1 mM uranium solution at pH 4.4 within 5 min 14.3 {+-} 5.5 mg U/g dry biomass and dead cells 28.3 {+-} 0.6 mg U/g dry biomass which corresponds to 45% and 90% of total uranium in solution, respectively. During 96 h of incubation with uranium initially living cells died off and with 26.6 {+-} 2.1 mg U/g dry biomass bound similar amounts of uranium compared to dead cells, binding 27.0 {+-} 0.7 mg U/g dry biomass. In both cases, these amounts correspond to around 85% of the initially applied uranium. Interestingly, at a lower and more environmentally relevant uranium concentration of 5 {mu}M, living cells firstly bind with 1.3 {+-} 0.2 mg U/g dry biomass to 1.4 {+-} 0.1 mg U/g dry biomass almost all uranium within the first 5 min of incubation. But then algal cells again mobilize up to 80% of the bound uranium during ongoing incubation in the time from 48 h to 96 h. The release of metabolism related substances is suggested to cause this mobilization of uranium. As potential leachates for algal-bound uranium oxalate, citrate and ATP were tested and found to be able to mobilize more than 50% of the algal-bound uranium within 24 h. Differences in complexation of uranium by active and inactive algae cells were investigated with a combination of time-resolved laser-induced fluorescence spectroscopy (TRLFS), extended X-ray absorption fine structure (EXAFS) spectroscopy and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Obtained results demonstrated an involvement of carboxylic and organic/inorganic phosphate groups in the uranium complexation with varying contributions dependent on cell status, uranium concentration and pH.

  7. Effects of plant growth regulators, carbon sources and pH values on callus induction in Aquilaria malaccensis leaf explants and characteris-tics of the resultant calli

    Institute of Scientific and Technical Information of China (English)

    Shashita JAYARAMAN; Nurul Hazwani DAUD; Rasmina HALIS; Rozi MOHAMED

    2014-01-01

    The endangered tropical tree, Aquilaria malaccensis, produces agarwood for use in fragrance and medicines. Efforts are currently un-derway to produce valuable agarwood compoundsn tissue culture. The purpose of this study was to develop an optimal growth medium, specif-ically, the best hormone combination for callus suspension culture. Using nursery-grown A. malaccensis, sterilized leaf explants were first incu-bated on basic Murashige and Skoog (MS) gel medium containing 15g/L sucrose and at pH 5.7. Different auxin types including 1-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), and indole-3-butyric acid (IBA), were tested at various concentrations (0.55, 1.1 and 1.65 µM) using the basic medium. Leaf explants were incubated for 30 days in the dark. Callus induced by 1.1 µM NAA had the highest biomass dry weight (DW) of 17.3 mg;however the callus was of a compact type. This auxin concentration was then combined with either 6-benzylaminopurine (BAP) or kinetin at 0.55, 1.1, 2.2 or 3.3 µM to induce growth of friable callus. The 1.1µM NAA+2.2µM BAP com-bination produced friable callus with the highest biomass (93.3mg DW). When testing the different carbon sources and pHs, sucrose at 15g/L and pH at 5.7 yielded highest biomasses at 87.7mg and 83mg DW, respec-tively. Microscopic observations revealed the arrangement of the friable cells as loosely packed with relatively large cells, while for the compact callus, the cells were small and densely packed. We concluded that MS medium containing 15 g/L sucrose, 1.1 µM NAA + 2.2 µM BAP hor-mone combination, and a pH of 5.7 was highly effective for inducing friable callus from leaf explants of A. malaccensis for the purpose of establishing cell suspension culture.

  8. Versatility of heme coordination demonstrated in a fungal peroxidase. Absorption and resonance Raman studies of Coprinus cinereus peroxidase and the Asp245-->Asn mutant at various pH values.

    Science.gov (United States)

    Smulevich, G; Neri, F; Marzocchi, M P; Welinder, K G

    1996-08-13

    The pH dependence of the electronic absorption and resonance Raman (RR) spectra of FeIII and FeII forms of Coprinus cinereus peroxidase (CIP) and its Asp245-->Asn (D245N) mutant has been examined in detail. The spectral data were obtained in the pH range 3.8-12.0. These spectra were used to assess the spin and ligation states of the heme via the porphyrin marker band frequencies and the wavelengths of the absorption maxima, especially that of the band (CT1) due to the charge transfer from the porphyrin to the heme iron via the a' 2u(pi)-->eg (d pi) electronic transition. The RR spectra were obtained by using different excitation wavelengths and polarized light. The data obtained for ferric CIP show that two pH-induced structural transitions exist. At acid pH the Soret and the CT1 absorption maxima occur at 394 and 652 nm, respectively, compared with the values of 403 and 649 nm observed at neutral pH. The electronic data indicate that at acid pH the proximal Fe-Im bond might be weakened or ruptured, and the RR spectra show a new species (5-c HS) different from the normal neutral 5-coordinate high-spin (5-c HS) heme. At pH 12.0, the protein converts to a 6-coordinate low-spin (6-c LS) heme with a hydroxyl ligand coordinated in the sixth position of the heme iron and strongly hydrogen-bonded with the positively charged guanidinium group of the distal Arg51 residue. Replacement of the aspartate carboxylate group of Asp245, which acts as hydrogen-bond acceptor to the proximal His183 ligand of the heme Fe, with a carboxamide group of an asparagine residue has a profound influence on the heme coordination. The RR spectra of the Fe(II) form of this mutant at both neutral and alkaline pH values show a band at 204 cm-1 assigned to the Fe-His stretch associated with a fairly weak or non-hydrogen-bonded imidazole. The ferric form of the mutant shows a great variability in coordination and spin states upon pH titration. Between pH 8.8 and 3.8 the spectra are mainly

  9. Effect of pH values on surface modification and solubility of phosphate bioglass-ceramics in the CaO-P 2O 5-Na 2O-SrO-ZnO system

    Science.gov (United States)

    Li, Xudong; Cai, Shu; Zhang, Wenjuang; Xu, Guohua; Zhou, Wei

    2009-08-01

    The bioactive glass-ceramics in the CaO-P 2O 5-Na 2O-SrO-ZnO system were synthesized by the sol-gel technique, and then chemically treated at different pH values to study the solubility and surface modification. Samples sintered at 650 °C for 4 h consisted of the crystalline phase β-Ca 2P 2O 7 and the glass matrix. After soaking in the solution at pH 1.0, the residual glass matrix on the surface appeared entirely dissolved and no new phase could be detected. Whereas at pH 3.0, web-like layer exhibiting peaks corresponding to CaP 2O 6 was formed and covered the entire surface of the sample. When conducted at pH 10.0, only part of the glass matrix was dissolved and a new phase Ca 4P 6O 19 was precipitated, forming the petaline layer. The chemical treatment can easily change the surface morphologies and phase composition of this bioactive glass-ceramics. The higher level of surface roughness resulting from the new-formed layer would improve the interface bonding and benefit for cell adhesion.

  10. 生物质酶催化过程中pH值的非线性控制%Nonlinear control of pH value in biomass catalytic process

    Institute of Scientific and Technical Information of China (English)

    何献忠

    2013-01-01

    The pH neutralization process has the highly nonlinear characteristic, when you add neutralizer or interference, pH value near the neutralization point changes a lot, while the pH value in the else points are opposite. It is very difficult to control. According to the characteristics of the pH controls in enzyme catalysis, using a parameter adaptive state controller and Hammerstein model control strategies, employing recursive least squares parameter estimation, static nonlinear characteristics of the controller upside down process non-linear part of the compensation and Hammerstein model is used to design the nonlinear model predictive control algorithm. Compared with other controller state for a difficult to control process this has a very good effect. The system engages in uncertainties real-time compensation, so as to improve the enzyme catalytic process in the stability of the enzyme activity. When the temperature random variation occurred, we carried out various controls in the field experimental study, in the enzyme-catalyzed process in the pilot test. Due to the mutual coupling of the temperature and pH in the catalytic process. The enzyme catalysis in the process of test, and the reaction time of 30 minutes and the simple PID control of the pH value of the large fluctuation, resulting in a big decrease in enzyme activity. The model reference adaptive controller under the control of the pH value of the wave is small, thus leading to a small decline in the range of enzyme activity, so as to enhance the catalytic process of the stability of the enzyme activity. In this way, converted into an approximate linear control for the pH of the enzyme catalysis process control not only enables the pH value highly nonlinear control, and automatically changes the controller tuning parameters, and solves the high degree of pH neutralization process linear control difficulties, but also improves the accuracy of the pH control in the enzyme catalysis process. pH

  11. pH值对右旋布洛芬体外透皮性能的影响研究%Effect of pH Value on in Vitro Percutaneous Permeability for Dextral Ibuprofen

    Institute of Scientific and Technical Information of China (English)

    刘丽清; 于秋菊; 谢茵; 任国莲; 石恩娴; 田青平

    2011-01-01

    目的:研究pH值对右旋布洛芬(DI)体外透皮性能的影响,为其透皮给药制剂的开发提供实验依据.方法:建立DI的高效液相色谱分析方法,测定其在水和不同pH的磷酸盐缓冲液(PBS)中的平衡溶解度;用摇瓶法测定DI的正辛醇溶液在正辛醇饱和蒸馏水与不同pH的PBS中的表现油水分配系数;以稳态渗透速率(Js)和渗透系数(Ps)为评价指标,检测不同pH的PBS对DI体外透皮性能的影响.结果:32℃时,DI在水中难溶;在pH7.4的PBS中平衡溶解度、Js、Ps均最大,表观油水分配系数极小,分别为5 421.6 μg·mL-1、339.97 μg·cm-2·h-1、0.063 cm·h-1、0.17.结论:pH值对DI体外透皮性能有很大影响,pH7.4时DI有较高的溶解度、脂溶性及较理想的皮肤通透性.%OBJECTIVE: To study the effect of pH value on in-vitro percutaneous permeability of dextral ibuprofen (DI) and to provide experimental basis for the development of percutaneous agent. METHODS: HPLC method was established to determine the equilibrium solubility of DI in water and phosphate buffer solution (PBS) with different pH values. Shaking-flask method was used to measure the apparent oil-water distribution coefficient of DI in the n-octyl alcohol saturated water or PBS with different pH values. The effect of PBS with different pH values on in-vitro percutaneous permeability of DI was evaluated using the steady-state permeation rate (J.) and permeation coefficient (P.) as index. RESULTS: At 32 ℃, DI was hardly soluble in water; the equilibrium solubility, J., P. of DI in PBS with pH 7.4 were the highest while apparent oil-water distribution coefficient was close to minimum value. They were 5 421.6 μg·mL-1, 339.97 μg·cm-2·h-1, 0.063 cm·h-1, 0.17, respectively. CONCLUSION: The in-vitro percutaneous permeability of DI is greatly influenced by the pH of media. Adjusting pH to 7.4, higher solubility and liposolubility of drug are maintained as well as percutaneous permeability.

  12. Study on the Influence of the pH Value on the Interactions between Fluoroquinolones and Bovine Serum Albumin%pH对氟喹诺酮药物与BSA之间相互作用影响的研究

    Institute of Scientific and Technical Information of China (English)

    刘世旺; 徐艳霞; 夏小环

    2009-01-01

    The interactions between four fluoroquinolones (pefloxacin, levoxfloxacin, oxfloxacin, and ciprofloxacin) and bovine serum albumin(BSA) were studied by capillary zone electrophoresis. The migration behaviors of the fluoroquinolones were investigated in a series of running buffers containing different concentrations of BSA. The binding constants of the fluoroquinolones and BSA were calculated at pH values of the running buffer of 6.8, 7.4 and 8.0, respectively. Results showed that pH value has a great influence upon the interactions between fluoroquinolones and BSA, and the binding constants of four fluoroquinolones and BSA reach the maximum at pH 6.8. The binding constants decrease gradually with the increasing of the pH value. The binding type and site between fluoroquinolones and BSA were investigated in detail. Study on the influence of pH value on the binding constants would be very helpful for the drugs' pharmacokinetic profiles evaluation and further drug discovery.%采用毛细管区带电泳法,通过测定在不同pH值、不同牛血清白蛋白(BSA)浓度缓冲溶液的条件下药物迁移时间的变化,并分别计算出了pH为6.8、7.4和8.0时培氟沙星、左氧氟沙星、氧氟沙星、环丙沙星等四种氟喹诺酮类药物与BSA相互作用的结合常数.结果表明:pH对结合常数有较大影响,四种药物分子结合常数的最大值均出现在pH=6.8时,并随着pH的增大,结合常数值明显下降.根据实验结果,还对四种氟喹诺酮类药物与BSA之间相互作用的类型、作用位置进行了分析探讨.研究结果对于进一步阐明药用机理并迅速开发出更高效的广谱抗菌药物具有较强的理论意义.

  13. 不同pH值L-精氨酸诱导小鼠急性胰腺炎模型效果观察%Effect of Acute Pancreatitis Model Induced by Different pH Values of L-arginine

    Institute of Scientific and Technical Information of China (English)

    石占利; 陈芝芸; 高凯

    2013-01-01

    Objective: To investigate the effect of acute pancreatitis model induced by different pH values of L-arginine. Methods: Seventy BABL/C mice were randomly divided into 3 groups. Two groups were treated with L-arginine solution of pH 11 and pH 8,respectively. L-arginine solutions were intraperitoneally injected 250mg/100g body weight twice at an interval of 1 hour. Another group served as control and was treated with same vol⁃ume of saline. Serum amylase was determined and pancreas pathological score and mortality rate were calculated in all groups at the time of 24 and 48 hours after injection. Results: Compared with the control group, the se⁃rum amylase levels were significantly increased in the pH11 group and pH8 group at the time of 24 and 48 hours(P<0.01). Compared with the pH11 group, the serum amylase levels in the pH8 group were significantly de⁃creased at the time of 24h and 48h(P<0.01), meanwhile, the pancreas pathological score and mortality rate in the pH8 group were also decreased significantly at both time points(P<0.05). Conclusion: The pH value of L-ar⁃ginine solution has a significant impact on the degree of pancreatic injury and animal mortality. The strong alka⁃line of L-arginine which does damage to abdominal organs is an important reason for instability of acute pancre⁃as model.%  目的:观察不同pH值L-精氨酸腹腔注射诱导急性胰腺炎模型的效果.方法:70只BABL/C小鼠,随机分为pH11组、pH8组和对照组,分别采用pH值为11的20%L-精氨酸溶液、pH值为8的20%L-精氨酸溶液、等体积生理盐水,间隔1h 2次小鼠腹腔内注射(250mg/100g体质量)的方法.在24h和48h分别观测三组小鼠的血清淀粉酶、胰腺病理学评分,并统计死亡率.结果:pH11组、pH8组小鼠在24h和48h的血清淀粉酶水平均较对照组显著升高(P<0.05,P<0.01);PH11组较pH8组24h和48h血清淀粉酶水平均升高更明显(P<0.01);pH8组24h和48h胰腺病理评分均较pH11

  14. 浙江省标准农田土壤酸碱度现状及改良措施%Status of Soil pH Values of Standardized Farmlands in Zhejiang Province and Its Improvement Measures

    Institute of Scientific and Technical Information of China (English)

    边武英

    2009-01-01

    [Objective] The aim was to investigate the status of soil pH values of standardized farmlands in Zhejiang province and put forward the corresponding improvement measures. [Method] With the standardized farmlands of 83 counties in Zhejiang province as sampling points, the soil samples were conducted for collection, processing and storage according to referenced to NY/T 1121.1 and soil pH values were measured by using distilled water extraction and glass electrode. The pH values of standardized farmland of different types in different regions were compared. [Result] The percentage which soil pH values of standardized farmlands and paddy at all levels accounted presented a trend of reducing at the middle and rising at two ends, and the rising amplitude of the proportion of acid soils was more than that of alkaline soils. Compared with the structure of 2nd general soil survey,the ratio of farmlands with soil pH values of or lower than 5.5 was increased by 20.71%, and that with soil pH of or lower than 4.5 of farmlands was increased by 1.71%. There were obvious differences of the pH value of standardized farmland in different geomorphologic types and the order was as follows: coastal plain > water net plain > valley plain > hilly area. [Conclusion] Measures such as liming, increasing organic fertilizer and extending soil testing and fertilizer recommendation should be taken to prevent the phenomenon of soil acidification of farmland in Zhejiang Province fundamentally.%[目的] 调查浙江省标准农田土壤酸碱度的现状,提出相应的改良措施.[方法] 以浙江省83个县市区的标准农田为取样点,参照NY/T 1121.1对土壤样品进行采集、处理和贮存,采用蒸馏水浸提玻璃电极法测定土壤pH值,对全省不同类型、不同区域的标准农田pH值进行比较.[结果] 标准农田土壤和水稻土pH值各级所占百分比呈现中间降低两头上升的趋势,且酸性土壤所占比例上升幅度大

  15. Iron chelating active packaging: Influence of competing ions and pH value on effectiveness of soluble and immobilized hydroxamate chelators.

    Science.gov (United States)

    Ogiwara, Yoshiko; Roman, Maxine J; Decker, Eric A; Goddard, Julie M

    2016-04-01

    Many packaged foods utilize synthetic chelators (e.g. ethylenediaminetetraacetic acid, EDTA) to inhibit iron-promoted oxidation or microbial growth which would result in quality loss. To address consumer demands for all natural products, we have previously developed a non-migratory iron chelating active packaging material by covalent immobilization of polyhydroxamate and demonstrated its efficacy in delaying lipid oxidation. Herein, we demonstrate the ability of this hydroxamate-functionalized iron chelating active packaging to retain iron chelating capacity; even in the presence of competing ions common in food. Both immobilized and soluble hydroxamate chelators retained iron chelating capacity in the presence of calcium, magnesium, and sodium competing ions, although at pH 5.0 the presence of calcium reduced immobilized hydroxamate iron chelation. A strong correlation was found between colorimetric and mass spectral analysis of iron chelation by the chelating packaging material. Such chelating active packaging may support reducing additive use in product formulations, while retaining quality and shelf life.

  16. Effects of pH Value on Resin Deposition with the Presence of Calcium Ion%pH值对钙离子存在下树脂沉积的影响

    Institute of Scientific and Technical Information of China (English)

    王旭; 詹怀宇; 陈港; 罗巨生

    2004-01-01

    The effects of pH value on resin deposition with the presence of CaTM were studied by usingthe device of "Rotating-mixer" and the method of GC-MS analysis. It is found that the decrease of pHvalue results in resin deposition and pH7.0 is the turning point. The deposits were analyzed by GC-MSafter being separated into combined resins and free resins. Experimental results show that calciumsoaps and free resins contribute together to deposits formation. The combined resins would change intofree resins at low pH and high temperature. Acidic components play an important role in soapsformation and the soaps of fatty acids are more stable at low pH value.%采用旋转搅拌装置和GC-MS法研究了pH值对钙离子存在下树脂沉积的影响.发现pH值的降低会导致树脂的沉积,pH7.0是转折点.将这些树脂分离成结合树脂和游离树脂后进行GC-MS分析,结果表明,钙皂和游离树脂对沉积物的形成有共同的贡献,结合树脂在低pH值和高温下转变为游离树脂.酸性组分对钙皂的形成起重要作用,而脂肪酸皂在低pH值下更稳定.

  17. Groundwater quality and the relation between pH values and occurrence of trace elements and radionuclides in water samples collected from private wells in part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma, 2011

    Science.gov (United States)

    Becker, Carol J.

    2013-01-01

    From 1999 to 2007, the Indian Health Service reported that gross alpha-particle activities and concentrations of uranium exceeded the Maximum Contaminant Levels for public drinking-water supplies in water samples from six private wells and two test wells in a rural residential neighborhood in the Kickapoo Tribe of Oklahoma Jurisdictional Area, in central Oklahoma. Residents in this rural area use groundwater from Quaternary-aged terrace deposits and the Permian-aged Garber-Wellington aquifer for domestic purposes. Uranium and other trace elements, specifically arsenic, chromium, and selenium, occur naturally in rocks composing the Garber-Wellington aquifer and in low concentrations in groundwater throughout its extent. Previous studies have shown that pH values above 8.0 from cation-exchange processes in the aquifer cause selected metals such as arsenic, chromium, selenium, and uranium to desorb (if present) from mineral surfaces and become mobile in water. On the basis of this information, the U.S. Geological Survey, in cooperation with the Kickapoo Tribe of Oklahoma, conducted a study in 2011 to describe the occurrence of selected trace elements and radionuclides in groundwater and to determine if pH could be used as a surrogate for laboratory analysis to quickly and inexpensively identify wells that might contain high concentrations of uranium and other trace elements. The pH and specific conductance of groundwater from 59 private wells were measured in the field in an area of about 18 square miles in Lincoln and Pottawatomie Counties. Twenty of the 59 wells also were sampled for dissolved concentrations of major ions, trace elements, gross alpha-particle and gross beta-particle activities, uranium, radium-226, radium-228, and radon-222 gas. Arsenic concentrations exceeded the Maximum Contaminant Level of 10 micrograms per liter in one sample having a concentration of 24.7 micrograms per liter. Selenium concentrations exceeded the Maximum Contaminant Level of 50

  18. Extreme-Value Analysis of China's Emergency Coal Reserve Scale%中国应急煤炭储备规模极值分析

    Institute of Scientific and Technical Information of China (English)

    牟敦果

    2012-01-01

    应急煤炭储备是中国特有的问题,但国内对其规模的定量研究非常少。本文从中国煤炭运输格局、发电用煤需求波动角度研究了建立国家级和省级应急煤炭储备省份的选择,运用极值分析方法研究了煤炭输入省份发电耗煤变动的极值冲击情况,确定了应对不同概率的发电用煤需求冲击的煤炭储备规模,证明当前应急煤炭储备500万吨规模的目标太低。文章最后提出保障我国煤炭供应安全的政策建议:建立省级和国家级应急煤炭储备;建立煤炭产能储备和运力储备;继续扩大应急煤炭储备规模。%Emergency coal reserve is a problem appearing only in China, yet there are few quantitative studies about its scale. This paper analyzes the location choice for national and provincial reserves from coal transportation situation and coal de- mand fluctuation aspects. This paper uses generalized extreme-Value approach to study coal demand shocks, calculating the coal reserve scales against different coal demand shocks, proving that the scale of 5 million ton is too low to deal with even per year shock. At last, this paper puts forward some suggestions to guaranty China's coal supply security:establishing national and provincial levels of emergency coal reserve ; keep coal production and transportation capacity surpluses ; continues to enhance e- mergency coal reserve scale.

  19. pH值对Reppe法生产1,4-丁二醇加氢工艺的影响%Influence of pH Value on Hydrogenation Process for Producing 1, 4 - Butanediol with Reppe Method

    Institute of Scientific and Technical Information of China (English)

    李建立; 刘新波; 罗明周

    2012-01-01

    河南开祥精细化工有限公司4.5万t/a1,4-丁二醇装置采用Reppe法工艺技术。简述了该装置的加氢工艺流程和催化剂特性;建立了低压加氢反应器内物料的pH值与主产物BDO浓度以及产物中乙缩醛含量、羰基数、丁醇含量之间的关联曲线;确立了混合槽物料pH值(pH1)与低压加氢进料槽物料pH值(pH2)以及低压加氢反应器内物料pH值(pH3)三者之间的递减关系。研究结果表明:①将低压加氢反应器内物料pH值控制在7.0-7.5时,催化剂使用条件最佳,主产物BD0的含量最高,且各副产物浓度较低;②通过调整进料槽物料的pH值,可控制加氢反应器内物料的pH值。%The process technology with Reppe method has been adopted in the 1, 4 - Butanediol plant with a capacity of 45,000 t/a in Kaixiang Fine Chemistry Engineering Company Ltd. Author has briefly described the hydrogenation process flow and the characteristic of catalyst in this plant ; has established the relation curves among the medium pH value in low pressure hydrogenation reactor, BOD concentration of product, content of by-product acetal, carbonyl number and butanol content; has determined the progressively decreasing relation among the three parts of medium pH value (pHI) in mixing tank, medium pH value (pH2) in low pressure hydrogenation feed tank and medium value (pH3) in low pressure hydrogenation reactor. Researc- hing result indicates: (1) The operating condition is optimum, with a maximum content of the main products, and a lower concentration of every by-product, in case of tak- ing the medium pH value in low pressure hydrogenation reactor being controlled in 7.0-7.5. (2) The pH value of medium in Hydrogenation reactor can be controlled by means of controlling the pH value of medium in the feed tank.

  20. Extreme Heat

    Science.gov (United States)

    ... Landslides & Debris Flow Nuclear Blast Nuclear Power Plants Power Outages Pandemic Radiological Dispersion Device Severe Weather Snowstorms & Extreme ... Landslides & Debris Flow Nuclear Blast Nuclear Power Plants Power Outages Pandemic Radiological Dispersion Device Severe Weather Snowstorms & Extreme ...

  1. Correlation between Semen PH Value and Semen Parameters or Biochemical Analyses Results of Seminal Plasma%精液pH值与精液参数及精浆生化的相关性研究

    Institute of Scientific and Technical Information of China (English)

    陈帅垒; 王祖龙

    2012-01-01

    目的 探讨精液pH值与精液参数及精浆生化之间的相关性,明确精液pH值在精液质量检测中所具有的价值.方法 收集河南省中医院中西医结合生殖中心2009年1月-2011年3月资料完整的男性不育症患者精液分析及精浆生化记录616份,建立Excel数据库,采用SPSS 16.0统计软件,对精液pH值与精液参数及精浆生化进行相关性分析.结果 精液pH值和受试者精浆弹性蛋白酶、精液A级精子百分率、前向运动精子百分率及存活精子百分率呈正相关性(P<0.05);与精浆酸性磷酸酶、精浆锌呈负相关性(P<0.05);与年龄、精浆果糖、精浆α-糖苷酶、精液白细胞、精液量、液化时间、精子浓度、正常形态精子数量无明显相关性(P>0.05).结论 精液pH值和精液参数及精浆生化的多项数值均具有相关性,进一步研究精液pH值的影响,对于男性不育症患者的诊疗具有重要意义.%Objective To study the correlation between semen pH value and semen parameters and biochemical analyses results of seminal plasma, and evaluate the value of semen pH in the semen quality test. Methods The semen and biochemical analyses results of 616 male infertility patients in our hospital from January 2009 to March 2011 were collected and analyzed by u-sing SPSS statistical software to evaluate the correlation between semen pH value and semen parameters and biochemical analyses results of seminal plasma. Results The semen PH value was positively correlated to the seminal plasma elastase, rate of grade A sperm,rate of rapid progression motility sperm and sperm viability (P 0. 05) . Conclusion The semen PH value is closely correlated to the semen parameters and biochemical analyses results of seminal plasma. The further study on the influence of semen PH value should improve the diagnosis and treatment of male infertility patients.

  2. Effect of pH Value on Structure and Properties of Anodic Electrodeposited Mn-MoOxide%pH值对阳极电沉积Mn-Mo氧化物结构与性能的影响

    Institute of Scientific and Technical Information of China (English)

    史艳华; 赵杉林; 梁平; 王玲; 关学雷

    2016-01-01

    By correction to the thermodynamic calculation based on E0‐pH diagram of MnSO4‐SO2 -4 ‐H2 O plating system ,effective pH value range for anodic electrodeposition of M nO 2 phase structure materials got clear ,at 363K ,with Mn2+ concentration 0 .2mol · dm -3 .The influence law of the pH values was also obtained based on the characterization of the oxide structure and test of its electro‐chemical performance .The results show that pH value in the 0 .33‐3 .4 range ,with its increase and accordingly the conducive to the effective deposition of MnO2 type Mn‐Mo oxide .However ,although with pH value increasing ,deposition efficiency improves ,the coating quality gets degraded ,especially making the electrocatalytic performance of the oxide obviously deteriorated .It also shows that with pH value of plating solution 0 .5 ,obtained Mn‐Mo oxide has excellent coating quality and high electro‐catalytic activity .The reason is closely related to competition in oxygen evolution reaction during the preparation of the oxide .When pH value is small ,oxygen evolution reaction competition causes the solid‐liquid interface stirring ,the dendritic grow th of oxide gets inhabited and the diffusion layer gets thinning ,w hich promotes the nucleation of oxide on the electrode micro‐surface and makes grain re‐fined ,so as to improves the electrocatalytic performance of oxide .%通过热力学计算修正的 M nSO4‐SO2-4‐H2 O镀液体系平衡电势 E0‐pH图,明确了363K和 M n2+浓度0.2mol · dm -3时M nO2物相结构材料阳极电沉积有效pH值范围,通过对氧化物结构表征及电化学性能测试获得了pH值的影响规律。结果表明:pH值在0.33~3.4时,随着pH值增大,有利于MnO2物相结构Mn‐Mo氧化物的有效析出,但pH值增大虽可提高阳极电沉积效率,却造成镀层质量变差,电催化性能明显劣化,镀液pH=0.5时获得的Mn‐Mo氧化物具有优异的镀层质量和高

  3. 健康妊娠妇女阴道乳酸杆菌及pH变化的研究%The change of vaginal Lactobacilli and pH value in vaginal secretion of healthy women before and after pregnancy

    Institute of Scientific and Technical Information of China (English)

    孙文平; 罗红; 陈晨; 綦霞; 杨光; 赵春艳

    2011-01-01

    目的 研究健康妊娠妇女阴道乳酸菌数量及pH的变化与妊娠时间的关系.方法 选择20例健康非妊娠妇女,60例健康妊娠妇女(其中早期妊娠、中期妊娠及晚期妊娠各20例)阴道分泌物进行乳酸杆菌数量检测及pH测定,并对乳酸杆菌产生过氧化氢的情况进行检测.结果 随着妊娠时间的增加,乳酸杆菌的数量明显增高,伴随阴道分泌物的pH逐渐降低.结论 乳酸杆菌与健康妊娠妇女阴道的生物屏障和酸性环境的维持有重要关系.%Objective To study the relationship between pregnancy time and the changes of the number of vaginal lactic acid bacteria and pH value in vaginal secretions. Method 20 healthy non-pregnant women, 60 healthy pregnant women ( including early pregnancy, mid-pregnancy and late pregnancy, each 20 cases) were selected. The number of vaginal lactobacilli and pH value in vaginal secretions were detected, and the production of hydrogen peroxide by Lactobacillus were detected. Result With the time of pregnancy increasing, the number of lactobacilli increased significantly, while the pH value of vaginal secretion decreased. Conclusion Lactobacilli in vaginal secretions of healthy pregnant women are the biological barriers which maintein the acidic vaginal environment.

  4. Analysis of extreme events

    CSIR Research Space (South Africa)

    Khuluse, S

    2009-04-01

    Full Text Available ) determination of the distribution of the damage and (iii) preparation of products that enable prediction of future risk events. The methodology provided by extreme value theory can also be a powerful tool in risk analysis...

  5. pH值对纯菌种Ethanologenbacterium sp.nov R3产氢的影响%Effects of pH value on fermentative biohydrogen production with Ethanologenbacterium sp. nov R3 in continous stirred tank reactor

    Institute of Scientific and Technical Information of China (English)

    史沫男; 林永波; 邓洁璇; 陈红; 李永峰

    2011-01-01

    In this paper, Ethanologenbacterium sp. nov R3 was used as research microbe which was inoculated from continuous stirred tank reactor (CSTR). The temperature and HRT of CSTR were controlled at ( 35 ± 1 ) ℃ and 8 h respectively. The effects of influent pH value on fermentative biohydrogen production with R3 were showed in this paper. When influent pH value was 5.5, the capacity of R3 to produce hydrogen was best. In this influent pH value, biogas yield and hydrogen content respectively achieved 6.85 ~ 8.86 L/d and 59.44% ~65. 13%. COD removal and effluent pH value were mainly stable at 26% and 4.38.The average concentration of ethanol and acetic acid in VFAs were respectively 706 mg/L and 446 mg/L. R3 maintained ethanol - type fermentation characteristics all along.%以Ethanologenbacterium sp.nov R3(以下称为R3)为研究对象,将其接种入连续搅拌槽式反应器(continuous stirred tank reactor,CSTR)中进行发酵产氢实验,以葡萄饮料废水为底物,温度控制在(35±1)℃,水力停留时间为8 h,探讨了不同的进水pH值对纯菌种R3连续流厌氧发酵生物制氢的影响.实验证明,当进水pH值为5.5时R3的厌氧发酵产氢能力最强.此时,产气量和氢气体积分数分别达到了6.85~8.86L/d和59.44%~65.13%,COD去除率稳定在26%左右,出水pH值稳定在4.38左右.在总挥发酸中,乙醇和乙酸的平均质量浓度分别是706mg/L和446 mg/L.整个过程中,R3始终保持乙醇型发酵特性.

  6. Effects of temperature and pH value on Castanea henryi starch retrogradation%贮藏温度与pH对锥栗淀粉糊回生的影响

    Institute of Scientific and Technical Information of China (English)

    童金华

    2011-01-01

    Taking starch of Castanea henryi as the raw material,the effects of different storage temperatures and pH values on retrogradation of C.henryi starch were observed by the enzymatic experiment.The results showed that the starch paste was easy for retrogradation at the temperature of 4 ℃,and the retrogradation percentage reached 9.76% after 24 hours.Meanwhile C.henryi starch paste was easy for retrogradation when pH was 5 and 7,while the retrogradation percentage decreased when pH was 3 and 9.%以锥栗淀粉为原料,采用酶法研究不同贮藏温度和pH对锥栗淀粉糊回生的影响。结果表明:锥栗淀粉糊在贮藏温度4℃时易回生,1 d后的淀粉糊回生率已达9.76%;pH为5和7时,锥栗淀粉糊易回生,pH为3和9时锥栗淀粉糊回生延缓。

  7. The value of Anti-Mullerian hormone in low and extremely low ovarian reserve in relation to live birth after in vitro fertilization

    NARCIS (Netherlands)

    Reijnders, I.F.; Nelen, W.L.D.M.; Hout, J. in't; Herwaarden, A.E. van; Braat, D.D.M.; Fleischer, K.

    2016-01-01

    OBJECTIVE: To determine the relation of Anti-Mullerian hormone (AMH) with live birth after in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) in women with (extremely) low ovarian reserve. STUDY DESIGN: This study was a retrospective cohort study in a Dutch tertiary fertility

  8. The value of Anti-Mullerian hormone in low and extremely low ovarian reserve in relation to live birth after in vitro fertilization

    NARCIS (Netherlands)

    Reijnders, I.F.; Nelen, W.L.D.M.; Hout, J. in't; Herwaarden, A.E. van; Braat, D.D.M.; Fleischer, K.

    2016-01-01

    OBJECTIVE: To determine the relation of Anti-Mullerian hormone (AMH) with live birth after in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) in women with (extremely) low ovarian reserve. STUDY DESIGN: This study was a retrospective cohort study in a Dutch tertiary fertility c

  9. 24-hour esophageal pH-monitoring in children suspected of gastroesophageal reflux disease: Analysis of intraesophageal pH monitoring values recorded in distal and proximal channel at diagnosis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To assess values of 24-h esophageal pH-monitoring parameters with dual-channel probe (distal and proximal channel) in children suspected of gastroesophageal reflux disease (GERD).METHODS: 264 children suspected of gastroesophageal reflux (GER) were enrolled in a study (mean age χ = 20.78 ± 17.23 mo). The outcomes of this study,immunoallerrgological tests and positive result of oral food challenge test with a potentially noxious nutrient,enabled to qualify children into particular study groups.RESULTS: 32 (12.1%) infants (group 1) had physiological GER diagnosed. Pathological acid GER was confirmed in 138 (52.3%) children. Primary GER was diagnosed in 76 (28.8%) children (group 2) and GER secondary to allergy to cow milk protein and/or other food (CMA/FA) in 62 (23.5%) children (group 3). 32(12.1%) of them had CMA/FA (group 4-reference group),and in remaining 62 (23.5%) children neither GER nor CMA/FA was confirmed (group 5). Mean values of pH monitoring parameters measured in distal and proximal channel were analyzed in individual groups. This analysis showed statistically significant differentiation of mean values in the case of: number of episodes of acid GER,episodes of acid GER lasting > 5 min, duration of the longest episode of acid GER in both channels, acid GER index total and supine in proximal channel. Statistically significant differences of mean values among examined groups, especially between group 2 and 3 in the case of total acid GER index (only distal channel) were confirmed.CONCLUSION: 24-h esophageal pH monitoring confirmed pathological acid GER in 52.3% of children with typical and atypical symptoms of GERD. The similar pH-monitoring values obtained in group 2 and 3 confirm the necessity of implementation of differential diagnosis for primary vs secondary cause of GER.

  10. 土壤类型与酸碱度对紫杉生长发育的影响%Effect of Soil Types and pH Value on Growth of Taxus cuspidata

    Institute of Scientific and Technical Information of China (English)

    唐晓杰; 白玉文; 张涛; 程广有

    2015-01-01

    为了探讨土壤类型与酸碱度对紫杉生长发育的影响,选择沙壤土、旱田土、腐殖土、河沙和苔藓等5种土壤类型(沙壤土pH分别为4.5,5.0,5.5,6.0,6.5,7.0,7.5,8.5)进行盆栽试验.结果表明:不同类型土壤对紫杉生长影响不同,在腐殖质中高生长最好,新梢长度达16.9 cm;其次是沙壤土,新梢长度达14.5 cm;在腐殖土和沙壤土中栽培的紫杉总根长度较大,河沙与苔藓基质中侧根和白根数量多.盆土酸碱度影响紫杉生长,土壤pH在5.5~7.0时,树高生长量差异不大,新梢长度为12.6~13.3 cm;当土壤pH小于4.5或大于7.5时,高生长受到抑制;土壤pH在5.5~7.0时,总根长度和侧根数量最多.%In order to evaluate effect of soil types and pH value on growth of of Taxus cuspidata, sandy soil, upland soil,humus soil,river sand and moss were selected to cultivate,pH value was adjusted to 4. 5,5. 0,5. 5, 6. 0,6. 5,7. 0,7. 5 and 8. 5 respectively. These results indicated that there were significant variations of yew growth in different soils. The height of yew seedlings which planted in humus soil and sandy soil were superior to that of other soils,whose growth yields were 16. 9 cm and 14. 5 cm respectively. The root length of seedlings which planted in humus soil and sandy soil were superior to that of other soils. The amount of lateral root and albino root of seedlings which planted in river sand and moss were greater than those of other soils. There were significant variations of yew growth in different pH values. The height yield was no significant variation when the soil pH value was from 5. 5 to 7. 0,whose growth yield was from 12. 6 to 13. 3 cm. Nevertheless,the height yield was restrained when the soil pH value was less than 4 . 5 or greater than 7 . 5 . The root length and lateral root number was maximum when the soil pH value was from 5 . 5 to 7 . 0 .

  11. 凝乳粒的pH值对融化干酪品质的影响%Effect of curd particle's pH value on the quality of processed cheese

    Institute of Scientific and Technical Information of China (English)

    霍建新; 王燕; 原慧艳; 王演; 白彩艳; 李明

    2015-01-01

    研究了凝乳粒的pH值对融化干酪的品质的影响.通过对融化干酪主要成分、感官评价、质构分析和微观结构的测定,比较了凝乳粒pH值为6.0、5.8、5.6、5.4、5.2对融化干酪品质的影响.结果表明:随着pH值的降低,融化干酪的脂肪含量和蛋白质含量逐渐减少,含水率增加;凝乳粒pH值为5.6时,切面光滑平整、组织状态均一、口感细腻;具有最高的恢复性,硬度适中,较低的咀嚼度、胶着性、黏聚性和弹性;融化干酪的网络结构更加密实,质地均匀,融化干酪整个体系有最佳的乳化效果.%The effect of the curd particle' s pH value on the quality of processed cheese was studied.Combined with main compositions,sensory evaluation,texture profile analysis and electron scanning spectroscopy,we investigated the effects of pH value 6.0,5.8,5.6,5.4,5.2 on the quality of processed cheese,respectively.Results showed that with pH values decreasing,processed cheese exhibited higher moisture,lower fat content.At pH 5.6,processed cheese had a smooth texture,uniform tissue and delighted taste,higher resilience,moderate hardness,low chewiness,low gumminess,cohesiveness,and springiness.The network between proteins was more closed and the structure was more uniform in the processed cheese.The emulsification was also very good.

  12. 肝硬化患者血总胆汁酸水平、粪便 pH 值的临床意义%Clinical value of serum total bile acid and fecal pH in patients wi th hepatic ci rrhosis

    Institute of Scientific and Technical Information of China (English)

    吴旭; 代敏涛; 李卓

    2014-01-01

    Objective]To investigate the clinical value of serum total bile acid (TBA )and fecal pH in Child-pugh classification in patients with hepatic cirrhosis.[Methods]Seventy patients with hepatic cirrho-sis were enrolled and divided into three groups according to Child-pugh classification :A group(A grade ,13 cases) ,B group(B grade ,34 cases) ,C group(C grade ,23 cases) ,respectively.And 40 patients with chronic gastritis were enrolled as control.Automatic biochemistry analysator was used to measure serum TBA.Fecal pH value was detected by short range pH paper.[Results]The levels of fecal pH and serum TBA were signifycantly higher in patients with hepatic cirrhosis than those in control group (P0.05).No significant correlation was found between serum TBA ,fecal pH and different causes of hepatic cirrhosis(P> 0.05).[Conclusion]Serum TBA ,fecal pH is one of the sensi-tive indexes refectiong cell damage of hepatic cirrhosis.Fecal pH is affected by many factors ,w hich has less value than serum TBA on predicting the prognosis and degree of liver function in patients with he-patic cirrhosis.%[目的]探讨血清胆汁酸(TBA)水平和粪便pH值在肝硬化中的临床价值。[方法]对70例肝硬化患者(肝硬化组)、40例慢性胃炎患者(对照组)采用全自动生化分析仪检测其 TBA、精密pH试纸检测其粪便pH值。[结果]肝硬化组患者外周血 TBA水平、粪便 pH值分别为(52.88±47.88)μmol/L、6.88±0.71,对照组分别为(8.695±4.70)μmol/L、5.860±0.27;2组比较,血清TBA水平及粪便pH值均差异有统计学意义(P<0.01)。肝硬化组患者随着Child-pugh分级升高而TBA水平升高,各级间比较差异有统计学意义(P<0.05);但不同Child-pugh分级患者粪便pH值无改变。外周血TBA水平、粪便pH值与肝硬化病因无明显相关性。[结论]TBA、粪便pH值是反映肝硬化患者肝细胞损害的敏感指标之一,由于影响粪便pH值的因素较多,

  13. 一种基于混合神经网络的浮选pH值预测模型%Prediction Model for pH Value in Flotation Process Based on Hybrid Neural Network

    Institute of Scientific and Technical Information of China (English)

    唐朝晖; 杜金芳; 陈青

    2012-01-01

    矿物浮选过程中,矿浆pH值作为影响浮选效果的一个重要因素,是实现浮选过程监视及优化控制的一个重要参量.目前的pH值测定仪存在交叉污染、测量滞后等问题,难以获得实时准确的pH值.为使浮选运行在最优状态,在泡沫图像特征提取的基础上,提出一种基于自适应遗传混合神经网络的预测模型,该模型首先利用主元分析(PCA)方法对提取的多个图像特征进行降维,然后采用自适应遗传混合神经网络(AGA-HNN)建立PH值预测模型.最后将该模型应用于浮选现场,预测结果能够实时跟踪实际值,根据预测值实时调整工况条件,改善了浮选效果,提高了浮选效率.%In mineral flotation process, pH value is one of the flotation elements which affect the flotation performance significantly. It is very important for flotation process monitoring and optimized controtl. At present, pH determinator has the problem of cross contamination , measurement lag, and so on. So it is difficult to obtain real lime and accurate pH value. To make flotation limning in an optimal slate, a novel prediction model is proposed in this paper based on adaptive genetic hybrid neural network after extracting several image features. Firstly, feature dimension reduction is done by principal component analysia( PCA). Then prediction model is built through a-daptive genetic hybrid neural network( AGA-HNN). Finally, the model is applied to flotation field. Predicted value can well trace the actual value. At the same time, working condition is adjusted according to the predicted value. As a result, the flotation performance and efficiency are improved obviously.

  14. Using Dissolved Oxygen,Oxidation Reduction Potential and pH Value for Control Nitrogen Removal in SBR Process%以DO、ORP、pH控制SBR法的脱氮过程

    Institute of Scientific and Technical Information of China (English)

    高景峰; 彭永臻; 王淑莹; 曾薇; 隋铭皓

    2001-01-01

    In order to achieve on-line fuzzy control of nitrogen removal inSBR,a brewery wastewater was treated in a SBR.Variation patterns of ORP,DO and pH value during the removal of organic matters,nitrification and denitrification were studied in detail with different influent concentrations of ammonia nitrogen.The results show that the characteristic points and platforms of DO,ORP and pH value are repeated very well,and can be used as process control parameters for the removal of organic matters,nitrification and denitrification in a SBR process.%为实现SBR法脱氮在线模糊控制,以啤酒废水为研究对象,通过不同进水混合液氨氮浓度的试验,详细地研究了SBR法在去除有机物和硝化、反硝化过程中DO、ORP、pH的变化规律。试验表明,DO、ORP、pH的特征点和平台的重现性很好,可以作为SBR法去除有机物,硝化,反硝化的过程控制参数。

  15. Effects of chloride ion concentration and pH values on the corrosion behavior of Cr12Ni3Co12Mo4W ultra-high-strength martensitic stainless steel

    Institute of Scientific and Technical Information of China (English)

    Hui-yan Li; Chao-fang Dong; Kui Xiao; Xiao-gang Li; Ping Zhong

    2016-01-01

    The effects of Cl− ion concentration and pH values on the corrosion behavior of Cr12Ni3Co12Mo4W ultra-high-strength marten-sitic stainless steel (UHSMSS) were investigated by a series of electrochemical tests combined with observations by stereology microscopy and scanning electron microscopy. A critical Cl− ion concentration was found to exist (approximately 0.1wt%), above which pitting occurred. The pitting potential decreased with increasing Cl− ion concentration. A UHSMSS specimen tempered at 600°C exhibited a better pitting cor-rosion resistance than the one tempered at 400°C. The corrosion current density and passive current density of the UHSMSS tempered at 600°C decreased with increasing pH values of the corrosion solution. The pits developed a shallower dish geometry with increasing polariza-tion potential. A lacy cover on the pits of the UHSMSS tempered at 400°C accelerated pitting, whereas corrosion products deposited in the pits of the UHSMSS tempered at 600°C hindered pitting.

  16. Effects of chloride ion concentration and pH values on the corrosion behavior of Cr12Ni3Co12Mo4W ultra-high-strength martensitic stainless steel

    Science.gov (United States)

    Li, Hui-yan; Dong, Chao-fang; Xiao, Kui; Li, Xiao-gang; Zhong, Ping

    2016-11-01

    The effects of Cl- ion concentration and pH values on the corrosion behavior of Cr12Ni3Co12Mo4W ultra-high-strength martensitic stainless steel (UHSMSS) were investigated by a series of electrochemical tests combined with observations by stereology microscopy and scanning electron microscopy. A critical Cl- ion concentration was found to exist (approximately 0.1wt%), above which pitting occurred. The pitting potential decreased with increasing Cl- ion concentration. A UHSMSS specimen tempered at 600°C exhibited a better pitting corrosion resistance than the one tempered at 400°C. The corrosion current density and passive current density of the UHSMSS tempered at 600°C decreased with increasing pH values of the corrosion solution. The pits developed a shallower dish geometry with increasing polarization potential. A lacy cover on the pits of the UHSMSS tempered at 400°C accelerated pitting, whereas corrosion products deposited in the pits of the UHSMSS tempered at 600°C hindered pitting.

  17. INFLUÊNCIA DE DIFERENTES pH DO MEIO DE AQUECIMENTO NA RESISTÊNCIA TÉRMICA DE Neosartorya fischeri ISOLADO DO PROCESSO PRODUTIVO DE NÉCTAR DE MAÇÃ INFLUENCE OF DISTINCT PH VALUES IN THE THERMAL RESISTANCE OF NEOSARTORYA FISCHERI ISOLATED FROM APPLE NECTAR PROCESSING

    Directory of Open Access Journals (Sweden)

    B. C. M. SALOMÃ?O

    2008-08-01

    Full Text Available

    A resistência térmica de ascósporos de N. fischeri, isolados do concentrado de maçã, foi verificada utilizando-se tubos TDT (Thermal Death Time selados, e suco de maçã, a diferentes pHs, como meio de aquecimento. As curvas obtidas a 80, 85 e 90°C mostraram um “ombro” inicial evidenciando comportamento de morte não logarítmica. Assim, o cálculo dos parâmetros cinéticos foi realizado através da linearização das mesmas. Os valores de “1/k” obtidos em pH 2,5 foram 81,3; 16,0 e 0,9 minutos para 80, 85 e 90°C, respectivamente; em pH 3,5 foram de 153,8; 22,0 e 1,0 minutos e em pH 4,5 foram de 312,5; 38,6 e 2,2 minutos, para as mesmas respectivas temperaturas. O valor de Z* (equivalente a Z foi 5,0°C a pH 2,5 e o mesmo valor (4,6°C foi encontrado em pH 3,5 e 4,5. Os valores de esterilização F(95°C nos pHs 2,5; 3,5 e 4,5 foram respectivamente 44,6; 36,8, e 77,0 segundos, considerando-se a redução da população inicial em 6 ciclos logarítmicos. Como o tratamento térmico comercial normalmente aplicado ao suco de maçã é de 95°C/30s, pode-se concluir que este não será suficientemente seguro para atingir a probabilidade de sobrevivência de 1 ascósporo a cada 105 embalagens, o que seria esperado.

    The heat resistance of N. fischeri ascospores isolated from apple concentrate was verified using closed TDT (Thermal Death Time tubes, and apple juice as heating medium (at different pHs. The curves at 80, 85 and 90°C showed an initial “shoulder” due to non logarithmic death behavior. Then, the kinetic parameters calculation was performed by linearization .The 1/k values obtained at pH 2.5 were 81.3, 16 and 0.9 minutes at 80, 85 and 90°C, respectively; at pH 3.5 were

  18. Modelación de valores extremos: Un análisis preliminar de la precipitación mensual en La Habana; Extreme-value modelling: A preliminary analysis of monthly precipitation at Havana

    Directory of Open Access Journals (Sweden)

    Jesper Ryden

    2011-02-01

    Full Text Available El análisis estadístico de valores extremos es de suma importancia en muchos campos de la ingeniería.Este trabajo es una breve introducción a la modelación con distribución  de valores extremos. Consisteen la presentación de dos métodos básicos comúnmente empleados en el modelado de valores extremospara analizar el problema típico de estimación de valores de retorno. Como ilustración de los métodos,se investiga un conjunto de datos de la precipitación mensual en La Habana. Statistical analysis of extreme values is of importance in many fields of engineering. This paper willserve as a brief introduction to modelling with extreme-value distributions. A presentation of two common,basic methods is given to analyse the standard problem in extreme-value modelling of estimation of returnvalues. As an illustration of the methods, a data set of monthly precipitation at Havana is investigated.

  19. C-Reactive Protein and Procalcitonin Diagnostic Value in Congenital Infection in Newborns with Extremely Low and Very Low Birth Weight

    Directory of Open Access Journals (Sweden)

    O. V. Mikhaylova

    2015-01-01

    Full Text Available The high frequency of infectious complications in the early neonatal period of adaptation in infants with extremely low (ELBW and very low birth weight (VLBW attracts particular attention. The aim of our study was to evaluate the sensitivity (Se and specificity (Sp of C-reactive protein and procalcitonin in congenital pneumonia and congenital sepsis in newborn infants with extremely low and very low birth weight.Methods. In 160 preterm newborns that were included in our prospective study, 33 had early neonatal sepsis, 42 children had congenital pneumonia, and 85 infants were without neonatal infection. A comprehensive clinical and laboratoryinstrumental examination of the newborn was done, including determining the concentration of C-reactive protein and procalcitonin at the age of 48–72 hours of life. Results. Low sensitivity of CRP at the age of 48–72 hours of life in congenital sepsis and congenital pneumonia was observed. However, under these pathological conditions CRP and PCT are characterized by high specificity. It should also be noted that PCT has a high sensitivity in children with congenital sepsis aged 48–72 hours. Moreover, PCT also has a high specificity (Sp 80,6%, which determines its advantage in the use of sepsis diagnosis in extremely premature infants compared to CRP.Conclusion. Maximum specificity reaches 100%, co-located with the assessment of CRP and PCT, which determines the feasibility of using this combination for verification of congenital infectious conditions such as sepsis and pneumonia in children ELBW and VLBW aged 48–72 hours.

  20. Nitrate Content and pH- value Changes in Process of Salting Cucumber%黄瓜腌制过程中亚硝酸盐含量及pH值变化

    Institute of Scientific and Technical Information of China (English)

    周强; 刘蒙佳; 黄月妹

    2012-01-01

    以黄瓜为原料,测定在不同条件下保藏的泡菜中亚硝酸盐含量度pH值.研究结果表明,腌制初期泡菜中亚硝酸盐含量呈上升趋势,第3、4天泡菜中亚硝酸盐含量达到最大值,之后又逐渐下降.7d后泡菜中亚硝酸盐含量符合国标要求,盐度低(4%),“亚硝峰”出现得早,峰值小;盐度高(12%),“亚硝峰”出现得晚且峰值大.%Taking cucumber as the raw material, this study determined the nitrate content and pH - value of the pickle which was preserved under different conditions. The results indicated that: in the earlier salting period, the content of nitrite in the pickle showed an increasing trend, it reached the highest value on the 3rd or the 4th day after salting, and then it decreased gradually. The content of nitrate in the pickle met the requirement of national standard after seven days' salting. It was found that lower salinity (4% ) led to the earlier emergence and smaller value of "nitrate content peak", and higher salinity (12% ) caused the later emergence and bigger value of "nitrate content peak".

  1. 极限运动的魅力与当代价值%The charm and modern value of extreme sports

    Institute of Scientific and Technical Information of China (English)

    苏树斌

    2015-01-01

    极限体育运动简称“极限运动”,是20世纪新兴体育项目。极限运动有较大危险性,但人们对其乐此不疲。究其原因包括:青年叛逆文化的产生、主流文化的变化,人类个体的冒险、回归自然、追求时髦的天性,以及人类体验成功、自我突破的需要,促使人们投身其中。极限运动可以为参与者个人提供创造、超越、竞争意识,回归自然,天人合一,获得身份认同;同时具有强大的教育功能,推进主流文化的发展变化,体现了体育运动超越、竞争、创造精神。%Extreme sports activities are also called as“extreme sports”;they are sports events emerging in the 20th century. Extreme sports are quite dangerous, but people have been enjoying them tirelessly. The reasons for this in-clude the producing of youth rebellion culture, the changing of mainstream culture, human individuals’ nature to seek adventure, to return to nature and to pursue fashion, as well as human beings’ need for experiencing success and making self breakthroughs, which make people devote themselves to such sports. Extreme sports can provide individual participants with the awareness of creation, exceeding and competition, the feel to return to and integrate with nature, and identity recognition;they also have powerful educational functions, and they have boosted the de-veloping and changing of mainstream culture, embodied the exceeding, competition and creation spirit of sports.

  2. 不同培养条件下对阿萨希毛孢子菌生物被膜影响的研究%Research on biofilm formation of asahii trichosporon on different temperature and pH value

    Institute of Scientific and Technical Information of China (English)

    樊昕; 任晓萍; 李海涛; 杨蓉娅

    2011-01-01

    Ob jsctive To study the abilily of the form ation of T . asahii biofilm ( T . asahii BF ) in vitro on different ten perature and pH value .M ethods W ith T .asahii polystyrene surface form ation biofiln 48 h for evaluation siandard ,itwas observed different biofilm formation differences at 20℃ ,25℃ ,30℃ ,35 ℃ and40℃ .W ith T .asahii biofilm at30℃ for evaluation standard ,itw as observed different biofilm form ation differences at different pH valie .The activity of biofilm was measured and quantitative analyzed by XTT and absorbance .R esults It was observed that biofilm forming speed was more quick follow ing tem perature elevated during 30 -35℃ .But biofilm stabality was gradually reduce at more than 35-40℃ .Biofilm was not form ed at pH =5 .0 and pH=9 .0 .BF form-ing showed slowly non —lineargrowth .T . asahii biofilm began to m ature during 24-48 h,showed relative growth stagnation during 48 -56 h and decreased gradually after then . C onclusion D ifferent ten perature and pH value could affect signiScantly T . asahii biofilm fbm ation .The ability and extent to form biofilm of T . asahii was significantly enhanced at culture conditions that was 30-35℃ and pH =7.0.%目的 观察不同培养温度和pH培养基对阿萨希毛孢子菌(asahii trichosporon,T.asahii)生物被膜(biofilm,BF)形成的影响.方法 以T.asahii聚苯乙烯表面形成生物被膜48 h为评价标准,观察其在20℃, 25℃,30℃,35 ℃和40℃培养温度下观察T.asahii生物被膜的差异性;在30℃培养温度下应用不同pH培养基和采用XTT法测定生物膜活性并定量分析.结果 30℃-35℃下生物被膜形成能力最强,其随着温度不断升高,其生物被膜形成速度加快,但是40℃时稳定性逐渐降低;pH=5.0时和pH=9.0不能形成生物被膜;pH=7.0时生物被膜形成表现为缓慢的非线性生长,24-48 h生物被膜开始成熟,48 h-56 h间出现一相对的生长停滞期,此后逐渐下降.结论 不同培养温度和p

  3. 电磁场对结垢过程中电导率及pH值的影响%Influence of electromagnetic field on conductivity and pH value in fouling process

    Institute of Scientific and Technical Information of China (English)

    王建国; 何芳; 邸昊; 徐志明

    2013-01-01

    通过双路对比实验模拟现场换热设备结垢过程,基于水处理技术阻垢及缓蚀性能在线评价实验台的实验数据,利用多项式回归模型对变频电磁场作用下水质参数电导率、pH值的变化规律进行分析,结合Matlab和Origin处理软件基础性地研究磁场作用时间与多种水质参数的关系及影响程度,结果表明:水质参数电导率较pH值对电磁场参数的解释程度更高,电导率相比pH值对于建立电磁场参数与多水质参数之间的数学模型是更为重要的水质参数,得出了电磁场参数与电导率、pH值之间的数学模型,为建立多水质参数与电磁抑垢效果之间的数学模型提供了基础理论,并为探索电磁抑垢机理及应用提供了实验依据.%The fouling process of heat exchange equipment was simulated by the twin channel contrast experiment. Based on the experimental data of the water treatment technology and the fouling prevention and antii-corrosion effect of online evaluation experiment, the variation of conductivity and pH value under the influence of frequency conversion electromagnetic field was analyzed by using the polynomial regression model. The influence degree and relation between water quality parameters and magnetic acting time were fully analysed by using Matlab and Origin software. The results show that compared with pH value, the conductivity can better explain the electromagnetic field parameters and is more important for constructing the mathematical models of electromagnetic field parameters and multii-water quality parameters. The mathematical models of electromagnetic field parameters and conductivity, pH value were obtained, which provide the theoretical basis for the mathematical model of multi-water quality parameters and mitigation of fouling effect, and the experimental basis for the electromagnetic field anti-fouling mechanism and application.

  4. Physiological Response of Four Azalea Species to Water with Different pH Values%4个杜鹃品种对不同pH值灌溉水的生理响应

    Institute of Scientific and Technical Information of China (English)

    鲜小林; 陈睿; 秦帆; 万斌; 潘远智

    2013-01-01

    With four species of azalea as materials, we studied the growth and physiological indexes under pH 4. 5,5. 5,6. 5,7. 5,8. 5 irrigation water,in order to analysis the growth conditions with different acidity and alkalinity irrigation water. The results showed that; (1) With the pH increasing, the chlorophyll contents, superoxide dismutase activities, catalase activities and new shoot growth rates of four species increased firstly and then decreased, while the relative conductivities were contrary; (2) Under pH 5. 5, the chlorophyll contents of ' Mevrouw. A', ' Fugeer No. 1' and 'Green Glow', the CAT activities of 'Mevrouw. A'.'Spring Dance' and 'Green Glow' were maximum. The same to SOD activities and new shoot growth rates of the four species,while the chlorophyll content of 'Spring Dance' with pH 4. 5 treatment were maximum. The same to CAT activity of 'Fugeer No. 1'. Under pH 8. 5,all relative conductivities were maximum, while the other indexes were contrary; (3) With pH 4. 5~5. 5,the cultivation matrix which initial pH value was about 5. 0 could be maintained in the optimum pH range,about 5. 0. Therefore,azalea can grow well with the irrigation water of pH 4. 5 - 5. 5 in the Southwest, and 'Green Glow' even can grow with the untreated water of pH 7. 5. It is good for extension and breeding,also is a excellent resource for alkali tolerance rootstocks of azalea.%以4种杜鹃品种为材料,研究了pH 4.5、5.5、6.5、7.5(CK)、8.5的灌溉水对其生长发育和生理指标的影响,以分析杜鹃品种在不同酸碱性灌溉水浇灌下的生长情况,为杜鹃花品种的广泛推广提供核心种质资源和栽培管理奠定理论基础.结果表明:(1)4个杜鹃品种的叶绿素含量、SOD、CAT活性和新梢生长率总体上随灌溉水pH值的增加表现为先升高后降低的趋势,相对电导率变化则相反.(2)在pH5.5处理下,‘德国粉鹃’、‘富哥尔一号’和‘绿色光辉,的叶绿素含量最高,‘德国粉鹃’、

  5. 呼出气冷凝液pH值与迟发型VAP的相关分析%Relevance between pH value of exhaled breath condensate and late ventilator associated pneumonia

    Institute of Scientific and Technical Information of China (English)

    齐天杰; 阎锡新; 李帅; 李海涛

    2012-01-01

    OBJECTIVE To find out and master the relevance between pH value of exhaled breath condensate (EBC) and late ventilator associated pneumonia (VAP). METHODS A prospective study was conducted on 57 patients with late VAP hospitalized in ICU of Respiratory Department in the Second Hospital of Hebei Medical University from May 2009 to Apr. 2011. Meanwhile, 60 healthy cases were enrolled for control. The clinical data were collected to further calculate the pulmonary infection score (CPIS). In the same time, EBC of all patients were collected to measure pH value. Then the statistical analysis was carried out. RESULTS One hundred and seventy-three pathogenic bacteria were isolated from the secretion of EBC of the 57 patients, which mainly were Pseudo-monas aeruginosa and Acinetobacter baumannii, acounting for 24. 86% and 23. 70% , respectively. The pH value of EBC on diagnosis day of VAP declined obviously compaired with that on three days after tracheal intubation(t = 5. 802,P<0. 05)and that in healthy control group (t= 12. 146,P<0. 05). CONCLUSION The detection of pH value of EBC is helpful for the diagnosis of late VAP.%目的 探讨呼出气冷凝液pH值水平与迟发型呼吸机相关性肺炎发生及严重程度的相关性.方法 选取2009年5月-2011年4月在河北医科大学第二医院呼吸科ICU住院的迟发型呼吸机相关性肺炎患者57例及健康体检者60名;收集患者临床资料,计算临床肺部感染评分;并同步收集患者的呼出气冷凝液,测量pH值;之后行统计学分析.结果 57例迟发型VAP患者,有创机械通气期间下呼吸道分泌物共分离出病原菌173株,主要为铜绿假单胞菌及鲍氏不动杆菌,分别占24.86%及23.70%;迟发型VAP诊断当天呼出气冷凝液pH值较插管后第3天及健康对照组均有明显下降(t=5.802,P<0.05;t=12.146,P<0.05).结论 呼出气冷凝液pH值检测有助于迟发型VAP的诊治.

  6. NHE-1 miRNA转染所致细胞内pH值变化对BACE1的影响%Influence of reduced intracellular pH value by NHE-1 gene silence on BACE1

    Institute of Scientific and Technical Information of China (English)

    于国华; 方伯言

    2012-01-01

    Objective To transfect the adenovirus mediated NHE-1 miRNA into human neuroblastoma(SH-SY5Y), and investigate the expression of BACE1 with the condition of the change of intracellular pH value. Methods The human neuroblastoma (SH-SY5Y) cell were cultured, enrolled and randomly divided into 3 groups, named as normal control group, NHE-1 gene knock down group and negative control group, and structured the NHE-1 gene knock down model. The intracellular pH value was detected in each group by fluorescence spectrophotometer, cells were examined for mRNA and protein expression of BACE1 by Real-time PCR and Western blotting. Results Compared with control group, the intracel-lular pH value was significantly lower in NHE-1 gene knock down group by fluorescent probe method (P <0.01) , while it had no change in negative control group; furthermore, the BACE1 mRNA expression and protein level were significantly higher in NHE-1 gene knock down group than those in paired normal control group (P <0.01), the BACE1 mRNA expres-sion and protein level had no change in negative control group. Conclusions The lower intracellular pH value condition is responsible for the higher BACE1 expression.%目的 探讨腺病毒介导的人Na+-H+交换体-1(NHE-1) miRNA转染人源性神经母细胞瘤细胞株(SHSY5Y)后,细胞内pH值变化及其对β位淀粉样前体蛋白裂解酶1(BACE1)的影响.方法 培养SH-SY5Y,随机分为正常对照组、NHE-1基因敲低组和阴性对照组,并构建NHE-1基因敲低细胞模型.采用荧光分光光度计测定各组细胞内pH值,通过Real-time PCR及Western blotting检测BACE1 mRNA及蛋白表达.结果 与正常对照组相比,NHE-1基因敲低组细胞内pH值明显降低(P<0.01),阴性对照组细胞内pH值无明显变化;NHE-1基因敲低组细胞内BACE1 mRNA表达及蛋白含量明显增高(P<0.01),阴性对照组细胞内BACE1 mRNA表达及蛋白含量无明显变化.结论 细胞内pH值降低能够增强BACE1的表达.

  7. Extreme cosmos

    CERN Document Server

    Gaensler, Bryan

    2011-01-01

    The universe is all about extremes. Space has a temperature 270°C below freezing. Stars die in catastrophic supernova explosions a billion times brighter than the Sun. A black hole can generate 10 million trillion volts of electricity. And hypergiants are stars 2 billion kilometres across, larger than the orbit of Jupiter. Extreme Cosmos provides a stunning new view of the way the Universe works, seen through the lens of extremes: the fastest, hottest, heaviest, brightest, oldest, densest and even the loudest. This is an astronomy book that not only offers amazing facts and figures but also re

  8. 酸奶在储藏过程中酸度、pH值、细菌的变化%CHANGES OF ACIDITY,PH VALUE AND BACTERIA COUNT OF YOGURT DURING STORAGE

    Institute of Scientific and Technical Information of China (English)

    杜磊; 张光杰

    2011-01-01

    In the paper, we measured the acidity, the pH value and the viable count of Lactobacillus of yogurt stored at different temperatures to determine optimal storage conditions and the peak drinking period of yogurt.Firstly, we respectively stored the yogurt samples of the same batch at the normal temperature, 4 ℃ and - 18 ℃ ; then, we observed the sensory changes and measured the pH value and the acidity at different time points; finally, we calculated the viable count by plate count method. The study showed that the amount of lactic acid bacteria in the yogurt stored at normal temperature for 5 days was up to 4.6 × 108 cfu/mL, the acidity 85.7 °T, and pH 4.08, and the yogurt had a small amount of milk serum separated out and had a good taste; the amount of lactic acid bacteria in the yogurt stored at 4 ℃ for 13 days was up to 4.6 × l08 cfu/mL,the acidity 85.5 °T, and pH 4.05, and the yogurt had a good taste ; and the amount of lactic acid bacteria in the yogurt stored at -18 ℃ for 19 days was up to4.5 ×108 cfu/mL, the acidity 85.5 °T, and pH 4.06, but the tissue structure changed. So, the yogurt stored at 4 ℃ for 13 days was in the peak drinking period.%将酸奶储藏在不同温度条件下,通过测得其酸度、pH值和乳酸茵活茵数,得出使酸奶的品质变化最小、货架期较长的最佳储藏条件和酸奶的最佳饮用期.先将同批酸奶分别置于常温、4℃和-18℃下,在储藏期不同时间点进行观察,测定其pH值、酸度,观察其感官变化.采用平板茵落计数法计算活茵数.研究表明,常温储藏5 d的酸奶茵含量最高达到4.6×10.cfh/mL,酸度为85.7°T,pH=4.08,有少量乳清析出,口感适宜;4℃储藏13 d的酸奶茵含量最高达到4.6×103 cfu/mL,酸度为85.5°T,pH=4.05,口感适宜;-18℃储藏19 d的酸奶菌含量最高达到4.5×108 cfu/mL,酸度为85.5°T,pH=4.06,但组织结构已发生改变.故4 ℃储藏的酸奶13 d内饮用最好.

  9. Analysis of the Changes in the Value of Oral pH in Patients with Oral Complications and the Corresponding Nursing%口腔并发症病人口腔pH值变化与护理分析

    Institute of Scientific and Technical Information of China (English)

    李静; 张楠

    2015-01-01

    目的:分析和研究护理干预对口腔并发症患者口腔pH值的影响。方法整群选取2012年6月-2014年8月内科住院口腔pH值异常患者84例,将其按投币随机法分为观察组与对照组,每组各有患者42例。对照组患者给予常规口腔护理干预;观察组患者在常规口腔护理基础上加用pH纠正液含漱,将两组患者护理干预2周后的口腔pH值变化情况及口腔并发症发生情况进行对比。结果两组患者护理干预前、后口腔pH值相比较院两组患者护理干预前口腔pH值差异无统计学意义,P>0.05;观察组患者护理干预后口腔pH值明显高于对照组,P0.05. After nursing intervention, the oral pH value was much higher in the observation group than that in the control group, P<0.05. The incidence of oral complications in the observation group was obviously lower than that in the control group, P<0.05. Conclusion The incidence of oral complications in critical patients in Department of Internal Medicine is closely related to the abnormal oral pH value. Conventional oral nursing combined with gargling pH correction fluid plays a key role in preventing the incidence of oral complications and reducing the suffering of the patients.

  10. 可见/近红外光谱结合遗传算法无损检测牛肉 pH 值%Nondestructive determination of pH value in beef using visible/near-infrared spectroscopy and genetic algorithm

    Institute of Scientific and Technical Information of China (English)

    马世榜; 汤修映; 徐杨; 彭彦昆; 田潇瑜; 付姓

    2012-01-01

    In order to realize nondestructive and rapid determination of beef pH stored at 4℃ during its whole shelf-life, a laboratory visible/near-infrared spectroscopy system using visible/near-infrared spectroscopy and genetic algorithm was built to collect 120 beef samples' reflectance spectra in the 400-1700nm. These samples were stored at 4℃ for l-18days. The reflectance spectra of samples were performed with different pretreatments, such as multiplicative scatter correction (MSC), Savitzky-Golay(SG) smoothing method. The prediction model of multiple linear regression (MLR), partial least squares regression(PLSR) and least square-support vector machine(LS-SVM) were constructed for prediction of pH value in beef with full-spectrum and effective wavelengths selected by genetic algorithm(GA), respectively. The results showed that the MSC combined with SG smoothing was the best pretreatment, and the performance of models established with effective wavelengths selected by GA were better than the full-spectrum models, and the best performance was achieved by LS-SVM model, its correlation coefficient and standard deviation were 0.935 and 0.111, respectively. The prediction accuracy was improved. This study demonstrated that the LS-SVM model built by using visible/near- infrared spectroscopy with GA could nondestructively and rapidly determine pH value in beef during its whole shelf-life. This research provides a basis of further developing device for nondestructive and rapid determine pH value in beef.%为了实现牛肉在整个货架期内(4℃环境)pH值的无损快速检测,该文采用可见/近红外光谱技术并结合遗传算法(GA,genetic algorithm),搭建了可见/近红外光谱检测系统,采集储藏在4℃下1~18d的120个牛肉样品400~1 700 nm范围的光谱,用不同预处理方法处理,并分别建立全波段光谱和经过遗传算法提取有效光谱的预测牛肉pH值的多元线性回归( MLR,multiple linear regression)模型

  11. Extreme variations of pCO2 and pH in a macrophyte meadow of the Baltic Sea in summer: evidence of the effect of photosynthesis and local upwelling.

    Science.gov (United States)

    Saderne, V.; Wahl, M.; Herman, P. M. J.

    2012-04-01

    Since the rise of ocean acidification as a major scientific question, state of the art knowledge on pCO2 and pH in nearshore ecosystems are becoming crucial to drive the experimentalists. However, in temperate areas, such data are widely missing. In this study we investigated the variations of the carbonate system in the nearshore macrophyte meadows of the western Baltic Sea. These are key benthic ecosystems, providing spawning and nursery areas and food source to numerous commercially important species. In situ pCO2, pH (total scale), salinity and PAR irradiance were measured with a continuous recording unit dropped in a shallow macrophyte meadow (Eckernförde bay, western Baltic) during three different weeks in July, August and September 2011. Means (± SD) pCO2 / pHtot observed were respectively 382 ± 114 µatm / 8.188 ± 0.131, 239 ± 62 µatm / 8.218 ± 0.101 and 931 ± 668 µatm / 7.826 ± 0.398 in July, August and September. Mean (± SD) day / night pCO2 variations due to photosynthesis and respiration were 227 ± 88 µatm, 195 ± 100 µatm and 1488 ± 732 µatm in July, August and September. The observed variations of pCO2 were explained through a statistical model considering wind direction and speed together with PAR irradiance, proving the occurrence of local upwellings of hypercapnic water masses with late summer offshore winds. Those results are demonstrating the high variability of the carbonate system in nearshore macrophyte meadows depending on meteorology and biological activities. They highlight the need for future pCO2 scenarios for nearshore habitats.

  12. 透析液pH值和电导率测量仪的设计与试验%Design and experiment on the dialysate pH value and electrical conductivity measuring instrument

    Institute of Scientific and Technical Information of China (English)

    刘致滨; 宋文晓; 杨晶娟; 朱懿恒; 卢广文

    2012-01-01

    背景:在血液透析过程中,透析液的浓度直接决定了透析的效果.目的:旨在设计一种应用于测量透析液浓度的pH值和电导率的装置,并通过试验对测量仪的性能进行测试和分析.方法:开发用于测量透析液的pH值和电导率测量仪,提出一种频率可调的双极性间歇脉冲激励方法应用于电导率测量,极大地减少极化效应和电容效应对测量的影响,同时对电导率测量值进行温度校正.采用两点校正法对pH值进行标定,提高测量的精确度.结果与结论:测量仪样机在实际的透析液中进行相关试验.测量仪的pH值测量值和标准值的相对误差小于1%,电导率的测量值与标准值的相对误差小于0.5%.通过对比试验说明,可调频率的间歇双极性脉冲法比双极性脉冲法的误差小,能及时地跟踪透析液浓度的变化.结果表明,测量仪能够实现对透析液浓度的精确测量,满足血液透析机对透析液的实时检测要求,可以广泛应用于血液透析机中透析液的浓度检测中.%BACKGROUND: The dialysate concentration directly determines the efficacy of dialysis during the process of hemodialysis. OBJECTIVE: To design a measuring instrument of dialysate pH value and electrical conductivity and to test the performance of the measuring instrument through experiments.METHODS: The variable frequency of bipolar interim pulse method was put forward to reduce polarization and capacitance effect on the conductivity measurement tremendously while simultaneously temperature compensation was selected for electrical conductivity. Two-point correction method was used for calibration test to improve the accuracy measurement of pH value. RESULTS AND CONCLUSION: The trial manufactured carried experiment on the actual dialysate. The relative error between the calibration result and the accurate value for dialysate pH value was less than 1 % and that of electrical conductivity was less than 0.5%. Besides

  13. Effect of benflumetol on DNA content and pH value of the lysosome of Plasmodium berghei%本芴醇对疟原虫DNA含量及溶酶体pH值的影响

    Institute of Scientific and Technical Information of China (English)

    苏瑞斌; 时云林; 李国福; 赵京花

    2001-01-01

    Objective:To study the antimalarial mechanism of benflumetol (B). Methods: Flow cytometry (FCM) was used to analyze the effects of B and chloroquine (CQ) on DNA content of Plasmodium berghei and pH value of the lysosome of malarial parasites. Results: DNA content of the plasmodia not treated with any drugs was not changed in 24 hours,while benflumetol could decrease the DNA content: the DNA content began to decrease 2 h after the drug administration and reached the minimum by 16 h, but somewhat increased at 24 h after administration. The pH in the lysosome increased 1 h and restored premedication level 4 h after benflumetol administration. Chloroquine had the same effects on DNA and lysosome pH of malarial parasites.Conclusions: The antimalarial mechanism of benflumetol is directly related to its effect to inhibit the synthesis of DNA.%目的:探讨本芴醇的抗疟作用机制。方法:采用流式细胞术(FCM)分析了本芴醇和氯喹对鼠伯氏疟原虫K173株DNA含量及溶酶体pH值的影响。结果:对照组疟原虫DNA含量在各时间点没有显著变化。本芴醇单次给药后,随时间推移疟原虫DNA含量逐渐减少,药后2 h两给药组疟原虫红内期 DNA含量开始降低,到16 h降到最低,但药后24 h DNA含量又有所回升。本芴醇单次给药后1 h起疟原虫溶酶体pH值开始升高,药后3 h升至最高,药后4 h原虫溶酶体pH值恢复至药前水平。对照药氯喹对疟原虫DNA含量和溶酶体pH值也有相同影响。结论:本芴醇的抗疟作用与其抑制DNA合成相关,但与其升高溶酶体pH值的关系不明确。

  14. Study on the Optimun pH Value in the Addition of Alkali in Laojiao Dough%老酵面团对碱工艺最佳p H值的研究

    Institute of Scientific and Technical Information of China (English)

    毛羽扬; 朱在勤; 纪有华; 张文涛; 徐传骏

    2001-01-01

    Food made with dugh fermented with Laojiao naturally fermented dough tastes good and enjoyes perfect flavour. Organic acid was produced during fermentation and this acid should be neutralized by adding alkali.How much alkali should be added to achiveve the optimum flavour and taste has always been one of the difficult points in refreshment production technology. This study proved that the refreshments made of naturally fermented dough laojjao right after the addition of alkali and with the pH vlue between 6.15 ~6.20 could achieve good flavour. And the refreshments made of th laoj iao after the addition of alkali to be kept about 25 minutes in which the pH value could reach 6. 1 2 ~6.15,could gain even better flavour.%用老酵来发酵的面团其制品口感好,风味好。由于发酵过程产生有机酸需对碱中和,如何控制对碱量,达到最佳风味效果,历来为面点工艺上的一个难点。研究证明,发酵面团对碱后立即制作,其面团的pH值在6.15~6.20区域内,制成品的效果很好。发酵面团对碱再醒发25min后,其面团的pH值在6.12~6.15区域内,这时制成品的效果更好。

  15. 彩色多普勒超声诊断下肢静脉血栓临床价值%Clinical value of color doppler ultrasound in the diagnosis of thrombus of lower extremity veins

    Institute of Scientific and Technical Information of China (English)

    巫朝君; 黄友清; 黄智勇

    2014-01-01

    Objective To investigate the clinical value of color doppler ultrasound in the diagnosis of thrombus of lower extremity veins. Methods A total of 84 patients with thrombus of lower extremity veins(DVT) underwent color Doppler ultrasound and digital subtraction angiography (DSA), and analyzed the test results comparatively. Results Color doppler ultrasound diagnosed deep vein thrombosis(DVT) in 68 cases of all 84 patients, 49 cases were in the left low-er extremity (72.1%), 19 cases were in the right lower extremity (27.9%),patients were in the left more than in the right;In all 68 patients,39 cases were in acute stage,20 cases were in sub acute stage, 9 cases were in chronic period. DSA diagnosed lower extremity DVT in 66 cases in 68 cases diagnosed by color doppler ultrasound,DSA diagnosed lower extremity DVT in 64 cases, 4 cases that examined by DSA were negative. Color doppler ultrasound diagnosed normal in 18 cases, DSA found lower extremity DVT in 2 cases. Compared with the results of DSA examination, the sensitivity and the specificity of color doppler ultrasound for diagnosing DVT were 96.97% and 88.9%, the diagnostic consistency of both methods was high (Kappa=0.78). Conclusion Color doppler ultrasound is simple, fast and repro-ducible, it is high in consistency with DSA and has important value in the diagnosis of lower extremity DVT.%目的:探讨彩色多普勒超声对下肢静脉血栓(DVT)的诊断价值。方法对84例疑诊为下肢DVT的患者分别采用彩色多普勒超声和数字减影血管造影(DSA)检查,对检查结果进行对比分析。结果所有84例患者中,彩超诊断下肢DVT68例,左下肢49例(72.1%),右下肢19例(27.9%),左侧明显多于右侧;所有68例患者中,急性期39例,亚急性期20例,慢性期9例。DSA检查诊断下肢DVT66例。彩超诊断68例中,64例DSA检查诊断为下肢DVT,4例DSA检查阴性。彩超检查正常18例中,2例经DSA检查诊断为下肢DVT

  16. On the influence of cell size in physically-based distributed hydrological modelling to assess extreme values in water resource planning

    Directory of Open Access Journals (Sweden)

    M. Egüen

    2012-05-01

    Full Text Available This paper studies the influence of changing spatial resolution on the implementation of distributed hydrological modelling for water resource planning in Mediterranean areas. Different cell sizes were used to investigate variations in the basin hydrologic response given by the model WiMMed, developed in Andalusia (Spain, in a selected watershed. The model was calibrated on a monthly basis from the available daily flow data at the reservoir that closes the watershed, for three different cell sizes, 30, 100, and 500 m, and the effects of this change on the hydrological response of the basin were analysed by means of the comparison of the hydrological variables at different time scales for a 3-yr-period, and the effective values for the calibration parameters obtained for each spatial resolution. The variation in the distribution of the input parameters due to using different spatial resolutions resulted in a change in the obtained hydrological networks and significant differences in other hydrological variables, both in mean basin-scale and values distributed in the cell level. Differences in the magnitude of annual and global runoff, together with other hydrological components of the water balance, became apparent. This study demonstrated the importance of choosing the appropriate spatial scale in the implementation of a distributed hydrological model to reach a balance between the quality of results and the computational cost; thus, 30 and 100-m could be chosen for water resource management, without significant decrease in the accuracy of the simulation, but the 500-m cell size resulted in significant overestimation of runoff and consequently, could involve uncertain decisions based on the expected availability of rainfall excess for storage in the reservoirs. Particular values of the effective calibration parameters are also provided for this hydrological model and the study area.

  17. pH值调控对秸秆两阶段厌氧发酵产沼气的影响%Effect of pH Values Control on Biogas Production of Agricultural Straw with Two-phase Anaerobic Fermentation

    Institute of Scientific and Technical Information of China (English)

    陈广银; 曹杰; 叶小梅; 杜静; 常志州

    2015-01-01

    , and methanogenesis. Large literature search showed that hydrolysis and acidification is the limiting step of biogas production of biosolid wastes. How to improve the hydrolysis and acidification rate of biosolid wastes? Much work has been done, including pretreatment, co-digestion, high efficient microbial inoculants, fermentation process control, et al. PH value is an important factor to hydrolysis and acidification of biosolid wastes. Much work has been done on characteristics of hydrolysis and acidification of biosolid wastes in acidic environment, but there was little information on characteristics of hydrolysis and acidification of biosolid wastes in alkaline environment. In order to evaluate the effect of alkaline environment control on hydrolysis and acidification and subsequent biogas production of agricultural straw, changes of daily biogas yield, methane content, pH value, COD content of hydrolysis and acidogenic phase and characteristics of biogas production of methanogenic phase were studied. The results showed that two-phase anaerobic fermentation of agricultural straw could be operated normally and TS biogas yield and average methane content were 281.28mL/g TSadded and 47.36%, respectively. Cumulative biogas yield of hydrolysis and acidogenic phase, average methane content and cumulative methane yield of treatment of adjusting pH value of hydrolysate to 8.0 daily was improved by 24.51%. 2.5 percent and 29.39%. Adjusting pH value of hydrolysate to 9.5 and 11.0 daily could inhibit biogas production of hydrolysis and acidogenic phase and increase COD content of hydrolysate, but it was bad for biogas production of hydrolysate and cumulative biogas yield of methanogenic phase were only 89.97% and 17.48% to that of CK. Maintaining hydrolysis and acidogenic phase in alkaline environment was beneficial for dissolving out of hemicellulose and lignin but bad to cellulose.

  18. 非奇次空间动态极值估计的模型与应用%The Model and Application of the Inhomogeneous Time Dynamic Extreme Value Theory

    Institute of Scientific and Technical Information of China (English)

    胡斌; 邹辉文

    2012-01-01

    传统EVT方法是从静态的角度,研究超额数据的性质.然而,它没有同时考虑极端数据发生的时间所隐含的充分信息.本文首次在国内提出了非奇次空间动态极值理论(ITD-EVT)的概念,克服了EVT的上述缺陷,在极端数据的基础上考虑了时间因素,并引入多个解释变量,使极值分布的是三个参数为时变的,用二维泊松分布过程建立动态空间模型,是文中一大特色.把TD-EVT运用于极端情况下风险值的估计中,对金融风险管理、资产定价等问题有较大的理论和现实意义.%The number of financial crisis has been growing since the 1990s. A country's financial crisis can eventually lead to international financial crisis in the global economy. The abnormal fluctuations of asset prices are becoming an important financial risk management topic. Extreme Value Theory method (KVT) is the most suitable method used to calculate the tail risk of financial assets in the extreme and unusual circumstances. As can be seen from the domestic and international research on EVT used in risk assessment, most literature studies the nature of obtaining exceedances over the threshold from the whole sample.The traditional method of EVT assumes the estimated variable remains constant for a period of time. However, the static perspective does not consider the full information implicit in the time of occurrence of extreme data. In addition, the volatility of returns, clustering, long memory, the leverage and the extent of the fat tails and skew would increase the dynamics of parameter estimation. The static theory also does not consider current expectations and volatility and assume that samples are independent and identically distributed, and directly use EVT to calculate the quantiles of the tail of distribution to estimate VaR. In practice, samples are not guaranteed to be independent, and returns have a dynamic relationship. Therefore, static model may not be appropriate

  19. The clinical value of color Doppler ultrasound diagnosis of acute lower extremity deep venous thrombosis%彩色多普勒超声诊断下肢深静脉急性血栓的临床价值

    Institute of Scientific and Technical Information of China (English)

    雷声鸣; 童燕燕; 林继平

    2011-01-01

    Objective To evaluate the clinical value of color Doppler ultrasound in acute deep vein thrombosis diagnosis. Methods 38 patients acute deep venous thrombosis were treatment with color Doppler ultrasound then observed the, imaging features and the flow characteristics. Results The data in the diagnosis of acute thrombosis in 38 cases, 1 case of misdiagnosis, diagnosis rate of 97.44%, In which 37 patients with unilateral thrombosis, I case of thrombosis of both lower extremities; left lower extremity venous thrombosis in 27 cases, 10 cases of right lower limb thrombosis. Conclusion Color Doppler ultrasound examination for acute lower extremity deep venous thrombosis diagnosis has important clinical value, the preferred and reliable disease- based inspection methods.%目的 探讨彩色多普勒超声在下肢深静脉急性血栓诊断的价值.方法 应用彩色多普勒超声诊断39例下肢深静脉急性血栓,观察声像图特征及血流特点.结果 本组资料中诊断急性血栓38例,误诊1例,诊断符合率97.44%,其中单侧血栓37例,双下肢血栓1例;左下肢静脉血栓27例,右下肢血栓10例.结论 彩色多普勒超声检查对下肢深静脉急性血栓的诊断有重要的临床价值,为本病的首选和可靠的检查方法.

  20. Necessary Condition for Conditional Extreme Values under Equality Constrains and Application in the Theory of Optimization%等式约束条件极值存在的必要条件及其应用

    Institute of Scientific and Technical Information of China (English)

    唐军强

    2014-01-01

    The conditional extreme values for multivariable functions under equality constrains was investigated by start⁃ing from the method of Lagrange multipliers. The necessary condition for the existence of conditional extreme values was obtained by theory of linear equations. Its application in the theory of optimization was discussed. The optimal solution is obtained with this necessary condition by converting inequality constrains into equality constrains.%从拉格朗日乘子法出发,考虑多元函数在等式约束条件下的极值问题。由线性方程组理论得到多元函数在一个或多个等式约束条件下极值点存在的必要条件。并进一步考虑该条件在优化理论中的应用,通过将不等式约束转化为等式约束,运用等约束条件下极值存在的必要条件获得最优解。

  1. Lixiviação do ametryn em Argissolo Vermelho-Amarelo e Latossolo Vermelho-Amarelo, com diferentes valores de pH Ametryn leaching on Red-Yellow Latosol and Red-Yellow Ultisol with different pH values

    Directory of Open Access Journals (Sweden)

    S.R.B. Andrade

    2010-01-01

    Full Text Available Objetivou-se com este trabalho avaliar o potencial de lixiviação do ametryn num Argissolo Vermelho-Amarelo e num Latossolo Vermelho-Amarelo utilizados com pastagens no Brasil, com diferentes valores de pH. Para isso, foram avaliados 120 tratamentos (quatro solos associados a três intensidades de chuva e 10 profundidades, em parcela subdividida no delineamento inteiramente casualizado, com três repetições. Colunas de PVC de 50 cm de comprimento por 10 cm de diâmetro foram preenchidas com os solos e umedecidas; em seguida, aplicou-se o herbicida e simularam-se chuvas no topo delas, nas intensidades especificadas de acordo com o tratamento. Após 72 horas, todas as colunas foram dispostas na posição horizontal e abertas longitudinalmente, coletando-se amostras dos solos a cada intervalo de 5 cm de profundidade, para posterior extração e quantificação do herbicida e análise por cromatografia líquida de alta eficiência - CLAE. Posteriormente, no restante das amostras de solo, semeou-se ao longo de cada coluna a espécie indicadora Cucumis sativus. Concluiu-se que solos com baixo teor de matéria orgânica e/ou pH mais elevado apresentaram maiores índices de lixiviação do ametryn. Além disso, o método do bioensaio foi mais eficiente na confirmação da lixiviação do ametryn em comparação à CLAE.The objective of this work was to evaluate ametryn leaching potential in soil used for pasture in Brazil (Red-Yellow Latosol (LVA and Red-Yellow Ultisol (PVA with different pH values. Thus, 120 treatments were evaluated (four soils related to three rainfall intensities and 10 soil column depths. The experiments were arranged in a completely randomized design in split-plots and three replications. PVC columns of 10 cm diameter by 50 cm length were filled with the soil samples, moistened and placed upright for 48 hours to drain the excess water. The herbicide was applied and rainfall was simulated on top of the columns at intensities

  2. Ph3CCOOSnPh3.Ph3PO AND Ph3CCOOSnPh3.Ph3AsO: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    ABDOU MBAYE

    2014-08-01

    Full Text Available The mixture of ethanolic solutions of Ph3CCOOSnPh3 and Ph3PO or Ph3AsO gives Ph3CCOOSnPh3.Ph3PO and Ph3CCOOSnPh3.Ph3AsO adducts which have been characterized by infrared spectroscopy. A discrete structure is suggested for both, the environment around the tin centre being trigonal bipyramidal, the triphenylacetate anion behaving as a mondentate ligand.

  3. Effect of biochar on mineral nitrogen content in soils with different pH values%生物质炭对不同pH值土壤矿质氮含量的影响

    Institute of Scientific and Technical Information of China (English)

    罗煜; 赵小蓉; 李贵桐; 赵立欣; 孟海波; 林启美

    2014-01-01

    concentration. The causes for high fertility of these soils are multiple, but the source of the large amounts of organic matter and their high nutrient retention has been attributed to the extraordinarily high proportions of black carbon. Besides, the high available nitrogen (N) is from both direct nutrient addition by the biochar and greater nutrient retention. It is also reported biochar can influence soil N concentrations via affecting soil process, such as N transformation. However, it remains largely unknown how biochar affect N transformations.In this study, biochars were produced at 350°C (BC350) and 700°C (BC700) by using Miscanthus giganteus, and applied with and without ryegrass into soils with low (pH=3.8) and high pH values (pH=7.6) incubated for 180 days. Our results showed that the addition of biochar to soils had an average increase of total N content of 22% and 17%, respectively in acid and alkaline soils. Biochars had obvious effect on NH4+-N in acid soil. After 87 days of incubation, NH4+-N was declined to very low concentration. BC350 had a slight increase of NO3--N in acid soil. Compared with BC350, soils with BC700 significantly (p0.05) was observed in treatments with and without ryegrass, neither between day 87 and 180, suggesting mineralization was largely occurred at the early incubation time in the soil with biochar added. The effects of biochar on the form and content of soil mineral nitrogen were closely related to the biochar’s abilities including ammonium adsorption, enhancing soil pH value, enhancing ammonia volatilization, and microbial biomass nitrogen formation. In the practical application, using biochar as coating materials in producing the slow-release fertilizer to improve nitrogen use efficiency seems to be very promised, and more research is needed in this area in the near future.

  4. pH Dependence of microbe sterilization by cationic antimicrobial peptides.

    Science.gov (United States)

    Walkenhorst, William F; Klein, J Wolfgang; Vo, Phuong; Wimley, William C

    2013-07-01

    We recently described a family of cationic antimicrobial peptides (CAMPs) selected from a combinatorial library that exhibited potent, broad-spectrum activity at neutral pH and low ionic strength. To further delimit the utility and activity profiles of these peptides, we investigated the effects of solution conditions, such as pH and ionic strength, on the efficacy of the peptide antimicrobials against a panel of microorganisms. Peptide minimum sterilizing concentrations (MSCs) varied linearly with pH for each subtype within our family of CAMPs for all organisms tested. The peptides were much less effective against Gram-negative bacteria at high pH, consistent with a decrease in net positive charge on the peptides. A similar trend was observed for the fungus Candida albicans. Surprisingly, the opposite pH trend was observed with the Gram-positive Staphylococcus aureus. In addition, an additive ionic strength effect was observed with increasing buffer strengths at identical pH values. The extreme difference in the observed pH behavior between Gram-negative and Gram-positive organisms is attributed to the presence of native charged molecules in the much thicker peptidoglycan layer of the Gram-positive organism. The novel species-specific effects of pH observed here have important implications for applications using CAMPs and for the design of novel CAMPs.

  5. Magnetotactic Bacteria from Extreme Environments

    Directory of Open Access Journals (Sweden)

    Christopher T. Lefèvre

    2013-03-01

    Full Text Available Magnetotactic bacteria (MTB represent a diverse collection of motile prokaryotes that biomineralize intracellular, membrane-bounded, tens-of-nanometer-sized crystals of a magnetic mineral called magnetosomes. Magnetosome minerals consist of either magnetite (Fe3O4 or greigite (Fe3S4 and cause cells to align along the Earth’s geomagnetic field lines as they swim, a trait called magnetotaxis. MTB are known to mainly inhabit the oxic–anoxic interface (OAI in water columns or sediments of aquatic habitats and it is currently thought that magnetosomes function as a means of making chemotaxis more efficient in locating and maintaining an optimal position for growth and survival at the OAI. Known cultured and uncultured MTB are phylogenetically associated with the Alpha-, Gamma- and Deltaproteobacteria classes of the phylum Proteobacteria, the Nitrospirae phylum and the candidate division OP3, part of the Planctomycetes-Verrucomicrobia-Chlamydiae (PVC bacterial superphylum. MTB are generally thought to be ubiquitous in aquatic environments as they are cosmopolitan in distribution and have been found in every continent although for years MTB were thought to be restricted to habitats with pH values near neutral and at ambient temperature. Recently, however, moderate thermophilic and alkaliphilic MTB have been described including: an uncultured, moderately thermophilic magnetotactic bacterium present in hot springs in northern Nevada with a probable upper growth limit of about 63 °C; and several strains of obligately alkaliphilic MTB isolated in pure culture from different aquatic habitats in California, including the hypersaline, extremely alkaline Mono Lake, with an optimal growth pH of >9.0.

  6. Processes and equipments for energy saving and emission reduction in dyeing plants (XV)——Control of pH value%印染厂节能减排实用工艺装备技术(十五)——染色pH值的控制

    Institute of Scientific and Technical Information of China (English)

    陈立秋

    2012-01-01

    以染浴pH值对牛仔服水洗、两相法印花后快速蒸化和活性染料浸染效果的影响等方面为实例,阐述染整加工中pH值测控的重要性;分析了pH值在线检测及控制系统的组成和系统控制器与外围设施的关系.%Taking the influence of pH value on denim washing, rapid ageing after two-phase printing and reactive dip dyeing for examples, the importance of pH value control in textiles wet processing is expounded. The composition of on-line detection and controlling system of pH value, as well as the relationship between control system and peripheral equipments are analyzed.

  7. Biodegradation of Aromatic Hydrocarbons in an Extremely Acidic Environment

    Science.gov (United States)

    Stapleton, Raymond D.; Savage, Dwayne C.; Sayler, Gary S.; Stacey, Gary

    1998-01-01

    The potential for biodegradation of aromatic hydrocarbons was evaluated in soil samples recovered along gradients of both contaminant levels and pH values existing downstream of a long-term coal pile storage basin. pH values for areas greatly impacted by runoff from the storage basin were 2.0. Even at such a reduced pH, the indigenous microbial community was metabolically active, showing the ability to oxidize more than 40% of the parent hydrocarbons, naphthalene and toluene, to carbon dioxide and water. Treatment of the soil samples with cycloheximide inhibited mineralization of the aromatic substrates. DNA hybridization analysis indicated that whole-community nucleic acids recovered from these samples did not hybridize with genes, such as nahA, nahG, nahH, todC1C2, and tomA, that encode common enzymes from neutrophilic bacteria. Since these data suggested that the degradation of aromatic compounds may involve a microbial consortium instead of individual acidophilic bacteria, experiments using microorganisms isolated from these samples were initiated. While no defined mixed cultures were able to evolve 14CO2 from labeled substrates in these mineralization experiments, an undefined mixed culture including a fungus, a yeast, and several bacteria successfully metabolized approximately 27% of supplied naphthalene after 1 week. This study shows that biodegradation of aromatic hydrocarbons can occur in environments with extremely low pH values. PMID:9797263

  8. Influence of pH value on the evolution and the crystal structure of manganese sulfate skeleton%pH控制硫酸锰骨架的演化及其晶体结构

    Institute of Scientific and Technical Information of China (English)

    王璐; 孙丽; 宋江锋; 周瑞莎

    2015-01-01

    在DMF/H2 O/CH3 OH的混合体系中,反应温度为170℃,MnSO4·4H2 O盐溶液在pH=5和7的条件下,加热72小时,最终得到了结构不同的硫酸锰骨架[Mn2(SO4)3]·(H3O)2(1)和[Mn3(SO4)2(OH)2(H2O)2](2)。化合物结构通过单晶X-射线和红外光谱所表征,相应的晶胞参数:化合物1,立方晶系,空间群:P213,a=10.2009(12)Å,V=1061.49(37)Å3,GooF=1.158,Flack parameter 0.02(2),R1=0.0186(I>2sigma);化合物2,四方晶系,空间群:Pbcm,a=7.3214(15)Å,b=9.984(2)Å,c=13.291(3)Å,V=971.5(4)Å3,GooF=1.063, R1=0.0227(I>2sigma);单晶X射线分析显示化合物1是一个三维单手性硫酸锰骨架,化合物2是一个非手性羟基硫酸锰骨架。实验结果说明,pH值对硫酸锰骨架的改变起重要作用。%Under the mixed DMF/H2 O/CH3 OH,the MnSO4·4H2 O solution was heated for 72 hours at 170℃ at pH values 5 and 7, respectively,two manganese sulfate skeleton,[Mn2(SO4)3]·(H3O)2(1) and[Mn3(SO4)2(OH)2(H2O)2] (2) were ob-tained. Compounds 1 and 2 are characterized through single crystal X-ray diffraction and infrared spectrum. The corresponding cell parameters for compound 1,cubic crystal system,space group P213,a=10. 2009(12)Å,V=1061. 49(37)Å3,GooF=1. 158,Flack parameter 0. 02(2),R1=0. 0186(I>2sigma);for compound 2,tetragonal crystal system,space group Pbcm,a=7. 3214(15)Å,b=9. 984(2)Å,c=13. 291(3)Å,V=971. 5(4)Å3,GooF=1. 063,R1=0. 0227(I>2sigma). Single crystal X ray analysis showed that compound 1 is a 3D single chiral manganese sulfate skeleton however, compound 2 is a hydroxy manganese sulfate skele-ton. Experimental results show that pH value plays an important role in the evolution of manganese sulfate skeleton.

  9. Tail risk research for Shanghai composite index based on conditional extreme value model%基于条件极值模型的上证综指尾部风险研究

    Institute of Scientific and Technical Information of China (English)

    常昊; 梁冯珍

    2013-01-01

    Based on traditional ARMA-GARCH time series models,conditional extreme value theory(EVT) model were introduced and applied to do out of sample prediction and back testing about VaR and ES for Shanghai composite index.Research showed that ARMA -GARCH model with skewed t innovations,and conditional EVT models perform well for VaR and ES prediction.%在传统ARMA-GARCH时间序列模型的基础上,介绍条件极值模型并运用这些模型对近十几年来上证综指进行VaR和ES样本外预测与事后检验.研究表明假设新息序列为偏t分布的ARMA-GARCH模型与条件极值模型在预测VaR和ES方面均具有出色效果.

  10. La teoría de valor extremo y el riesgo operacional: una aplicación en una entidad financiera Extreme value theory and operational risk: an application to a financial institution

    Directory of Open Access Journals (Sweden)

    Juan Guillermo Murillo Gómez

    2009-07-01

    Full Text Available Este artículo presenta la aplicación de la teoría de valor extremo (EVT para cuantificar la distribución de pérdidas en riesgo operacional, a partir de datos internos y externos; se analizaron por separado las distribuciones de frecuencia y severidad, para luego combinarlas y hallar la distribución de pérdidas, la cual se dividió en dos áreas: el cuerpo hasta un umbral, y la cola.This paper presents the application of Extreme Value Theory (EVT in order to quantify the loss distribution in operational risk, from internal and external data; frequency and severity distributions were analyzed separately, then they were combined to find the loss distribution, which was divided into two areas: the body -until a threshold- and the tail.

  11. Competitive and synergistic effects in pH dependent phosphate adsorption in soils: LCD modeling.

    Science.gov (United States)

    Weng, Liping; Vega, Flora Alonso; Van Riemsdijk, Willem H

    2011-10-01

    The pH dependency of soluble phosphate in soil was measured for six agricultural soils over a pH range of 3-10. A mechanistic model, the LCD (ligand charge distribution) model, was used to simulate this change, which considers phosphate adsorption to metal (hydr)oxides in soils under the influence of natural organic matter (NOM) and polyvalent cations (Ca(2+), Al(3+), and Fe(3+)). For all soils except one, the description in the normal pH range 5-8 is good. For some soils at more extreme pH values (for low P-loading soils at low pH and for high P-loading soils at high pH), the model over predicts soluble P. The calculation shows that adsorption is the major mechanism controlling phosphate solubility in soils, except at high pH in high P-loading soils where precipitation of calcium phosphate may take place. NOM and polyvalent cations have a very strong effect on the concentration level of P. The pattern of pH dependency of soluble P in soils differs greatly from the pH effects on phosphate adsorption to synthetic metal (hydr)oxides in a monocomponent system. According to the LCD model, the pH dependency in soil is mainly caused by the synergistic effects of Ca(2+) adsorption to oxides. Adsorption of Al(3+) to NOM adsorbed plays an important role only at a pH < 4.5. Presence of NOM coating strongly competes with phosphate for the adsorption and is an important factor to consider in modeling phosphate adsorption in natural samples.

  12. The Regulation of pH Value of Liquid Feed on Blood Gas Parameters in Holstein Bull Calves%液体饲料pH值对荷斯坦公犊血气指标的调控

    Institute of Scientific and Technical Information of China (English)

    屠焰; 邱国梁; 周怿; 云强; 齐东; 王家杰; 刁其玉

    2014-01-01

    0.8126、0.8298。血液pH值和pCO2随日龄变化有显著改变(P<0.05);除HCO3-、ABE、SBE外,其他血气指标符合正态分布规律(P>0.05)。代乳品中植物蛋白占总蛋白的比例由50%提高到80%时,犊牛平均日增重和干物质采食量降低,但血气指标并未受到影响(P>0.05)。【结论】随代乳品乳液pH值的降低,21-63 d犊牛血液HCO3-、ABE、TCO2、SBC、SBE显著降低,可作为评价日粮酸度效果的敏感指标。%Objective] Due to the immature gastrointestinal function and low ability digest dietary, diarrhea or other nutritional diseases were easy to arise in suckling calves that bring about low survival rate. Compared with adult cattle, liquid milk replacer is the main feed for the early weaned calves. Thus, acidity of milk replacer emulsions has more important effect on calf health. But the change regulation, the normal value scope of blood gas parameters in calves are not in any systematic manner, so that it is unable to determine whether the appropriate dietary acidity is. To study the change regulations of blood gas parameter in calves, an experiment was carried out to investigate the variations of blood gas parameters in calves which fed liquid feed with different pH.[Method]The pH values of a milk replacer (6.2, 5.5, 5.0 or 4.5) and the ratio of vegetable protein to total protein in the milk replacer (50% or 80%) were used to form an 2 × 4 factorial design in this experiment. Forty-eight neonatal healthy Chinese Holstein male calves were allotted into eight groups and each group was fed with one of the 8 milk replacer emulsions. The experiment lasted 63 d with 21 d for adaptation and 42 d for test. Growth performance was determined fortnightly, the intake of milk replacers and pellet diet were recorded every day. Blood samples were collected on 21 d and 49 d. The pH value, partial pressure of carbon dioxide (pCO2), partial pressure of oxygen (pO2), oxygen saturation (SO2

  13. 彩色多普勒超声对下肢深静脉血栓形成的诊断价值%Application value of color Doppler ultrasound in diagnosing lower extremity deep venous thrombosis

    Institute of Scientific and Technical Information of China (English)

    靳静

    2016-01-01

    目的 探讨彩色多普勒超声对下肢深静脉血栓形成的诊断价值.方法 选取2011年3月至2015年11月河北省廊坊市人民医院行彩色多普勒超声检查的下肢深静脉血栓形成患者63例,结合患者临床表现,分析彩色多普勒超声检查结果.结果 63例下肢深静脉血栓形成患者经彩色多普勒超声检查,左下肢40例(63.5%),右下肢20例(31.7%),双下肢2例(3.2%),漏诊1例(1.6%),诊断率为98.4%(62/63).62例确诊患者中急性栓塞14例(22.2%),亚急性栓塞40例(63.5%),慢性栓塞8例(12.7%).结论 应用彩色多普勒超声对下肢深静脉血栓高危患者进行检查,无创安全、及时准确、可重复操作且经济便捷,为临床提供可靠的诊断依据,是诊断下肢深静脉血栓形成的首选辅助检查方法.%Objective To explore the value of color Doppler ultrasound in diagnosing lower extremity deep venous thrombosis.Methods Sixty-three cases with lower extremity deep venous thrombosis who underwent color Doppler ultrasound from March 2011 to November 2015 were enrolled.The results of color Doppler ultrasound were analyzed based on clinical data.Results Totally 40 cases (63.5%) of left lower limb,20 cases (31.7%) of right lower limb and 2 cases (3.2%) of bilateral lower limb deep venous thrombosis were diagnosed by color Doppler ultrasound,1 case (1.6%) was missed,with diagnostic rate of 98.4% (62/63);among the 62 patients,14 cases (22.2%) were confirmed as acute lower extremity deep venous thrombosis,40 cases (63.5%) were confirmed as subacute lower extremity deep venous thrombosis and 8 cases (12.7%) were confirmed as chronic lower extremity deep venous thrombosis.Conclusion Color doppler ultrasound is non-invasive,safe,timely,accurate,repeatable,inexpensive and convenient,and is a preferred method for diagnosing lower extremity deep venous thrombosis.

  14. Extreme Programming: Maestro Style

    Science.gov (United States)

    Norris, Jeffrey; Fox, Jason; Rabe, Kenneth; Shu, I-Hsiang; Powell, Mark

    2009-01-01

    "Extreme Programming: Maestro Style" is the name of a computer programming methodology that has evolved as a custom version of a methodology, called extreme programming that has been practiced in the software industry since the late 1990s. The name of this version reflects its origin in the work of the Maestro team at NASA's Jet Propulsion Laboratory that develops software for Mars exploration missions. Extreme programming is oriented toward agile development of software resting on values of simplicity, communication, testing, and aggressiveness. Extreme programming involves use of methods of rapidly building and disseminating institutional knowledge among members of a computer-programming team to give all the members a shared view that matches the view of the customers for whom the software system is to be developed. Extreme programming includes frequent planning by programmers in collaboration with customers, continually examining and rewriting code in striving for the simplest workable software designs, a system metaphor (basically, an abstraction of the system that provides easy-to-remember software-naming conventions and insight into the architecture of the system), programmers working in pairs, adherence to a set of coding standards, collaboration of customers and programmers, frequent verbal communication, frequent releases of software in small increments of development, repeated testing of the developmental software by both programmers and customers, and continuous interaction between the team and the customers. The environment in which the Maestro team works requires the team to quickly adapt to changing needs of its customers. In addition, the team cannot afford to accept unnecessary development risk. Extreme programming enables the Maestro team to remain agile and provide high-quality software and service to its customers. However, several factors in the Maestro environment have made it necessary to modify some of the conventional extreme

  15. Extreme value distribution of earthquake magnitude

    Science.gov (United States)

    Zi, Jun Gan; Tung, C. C.

    1983-07-01

    Probability distribution of maximum earthquake magnitude is first derived for an unspecified probability distribution of earthquake magnitude. A model for energy release of large earthquakes, similar to that of Adler-Lomnitz and Lomnitz, is introduced from which the probability distribution of earthquake magnitude is obtained. An extensive set of world data for shallow earthquakes, covering the period from 1904 to 1980, is used to determine the parameters of the probability distribution of maximum earthquake magnitude. Because of the special form of probability distribution of earthquake magnitude, a simple iterative scheme is devised to facilitate the estimation of these parameters by the method of least-squares. The agreement between the empirical and derived probability distributions of maximum earthquake magnitude is excellent.

  16. Effects of soil pH on the Vicia-micronucleus genotoxicity assay.

    Science.gov (United States)

    Dhyèvre, Adrien; Foltête, Anne Sophie; Aran, Delphine; Muller, Serge; Cotelle, Sylvie

    2014-11-01

    In the field of contaminated sites and soil management, chemical analyses only bring typological data about pollution. As far as bioavailability and effects on organisms are concerned, we need ecotoxicology tools. In this domain, among many existing tests, we chose to study genotoxicity because it is a short-term endpoint with long-term consequences. The aim of this study is to assess the effects of soil pH on the results of the Vicia faba root tip micronucleus test for the two following reasons: (i) to define the pH range within which the test can be performed without modifying the soil to be tested, within the framework of the ISO standard of the test and (ii) to provides information about the effects of the pH on the genotoxic potential of soils. In this context, we modified the pH of a standard soil with HCl or NaOH and we spiked the matrix with copper (2, 4 and 8 mmol kg(-1) dry soil) or with maleic hydrazide, an antigerminative chemical (5, 10 and 20 μmol kg(-1) dry soil). We concluded that the pH had no effect on the mitotic index or micronucleus frequency in the root cells of the negative controls: extreme pH values did not induce micronucleus formation in root cells. Moreover, according to our results, the Vicia-micronucleus test can be performed with pH values ranging between 3.2 and 9.0, but in the ISO 29200 "Soil quality--assessment of genotoxic effects on higher plants--V. faba micronucleus test" we recommended to use a control soil with a pH value ranging between 5 and 8 for a more accurate assessment of chemical genotoxicity. We also found that acid pH could increase the genotoxic potential of pollutants, especially heavy metals. With hydrazide maleic spiked soil, plants were placed in a situation of double stress, i.e. toxicity caused by extreme pH values and toxicity induced by the pollutant.

  17. Effects of Different Raw Material Proportions and Moistening Levels on pH Value and Enzyme Activity during Koj i-making Process%制曲过程中不同原料配比、润水量对成曲pH 值、酶活的影响研究

    Institute of Scientific and Technical Information of China (English)

    陈振伟

    2014-01-01

    Analyze the effects of different raw material proportions and moistening levels on pH value and enzyme activity during koji-making process,set six groups of different raw material proportions and moistening levels using the same kind of koj i under the same conditions.The result reflects that the effect of infeed-koji water content on finished koji pH value is greater than that of raw material proportion on pH value;while water has greater effect on finished koji enzyme activity than raw material proportion.%通过使用同一种曲,设定六组不同原料配比、润水量,在同一条件下进行制曲,研究了制曲过程中不同原料配比、润水量对成曲 pH 值、酶活的影响。结果表明:入曲水分对成曲 pH 的影响比原料配比对pH 的影响要大;成曲酶活受水分的影响比受原料配比的影响大。

  18. Dicarboxy-dichlorofluorescein: a new fluorescent probe for measuring acidic intracellular pH.

    Science.gov (United States)

    Nedergaard, M; Desai, S; Pulsinelli, W

    1990-05-15

    Derivatives of fluorescein sensitive to pH are extensively utilized for the determination of intracellular pH (pHi). Available dyes have pKa values of approximately 7.0, and are not well suited for measuring acidic pHi. We examined the fluorescein derivative, 5 (and 6)-carboxy-2',7'-dichlorofluorescein (CDCF) for its potential in the microspectrofluorometric measurement of pHi during acidic conditions. CDCF showed intense fluorescence and pH sensitivity near its "effective" pKa value of 4.2, using a 495/440 nm dual excitation wave-length ratio method. Protein interactions caused fluorescence ratio deviations which were most pronounced at the extremes of pH, whereas calcium and magnesium concentrations had little effect on the fluorescent ratio intensity. Intracellular calibration performed using nigericin in the presence of high potassium eliminated the need to correct for protein interactions, and the ratio method minimized any variations due to dye concentration differences or instrument fluctuation. Intracellular retention of the dye was high, and 95% of the initial signal remained after 1 h. Fluorescence bleaching was 14.5% after 1 h of continuous excitation and cell survival was not affected by dye loading. We conclude that CDCF is an excellent intracellular pH indicator in the pH range of 4-5.

  19. Design and Application of Online Determination and Control System of pH Value for Spherical Ni(OH)2 PreParation%球形Ni(OH)2制备中pH在线检测及控制系统的设计和应用

    Institute of Scientific and Technical Information of China (English)

    李涛; 陈飞彪; 郭荣贵; 傅钟臻; 于丽敏; 夏雯; 蒋文全

    2011-01-01

    During the preparation of the spherical Ni(OH)2, pH meter may be influenced by some environmental factors, such as high salinity, high alkalinity, high temperature and strong convection. The stability and lifetime of pH meter would be shortened, and the determination and control of pH parameter are difficult. So a set of the online determination and control system of pH value are designed. The method determining the relative pH value outside of the reactor is introduced and the online determination device of pH value is designed. It implements the narrow-range fluctuation from 0. 02 to 0. OS Of pH valve. Meanwhile the control system based on configuration software and programmable logic controller ( PLC) is designed and there is a good result in real-time.%在球形Ni(OH)2制备过程中高盐度、高碱度、高温和强对流的环境因素导致pH电极稳定性降低,寿命缩短,pH参数检测和控制困难,为此采用反应釜外检测相对pH值的方法,设计pH在线检测装置和基于组态软件和可编程控制器的pH值在线控制系统,实现了pH值在0.02~0.05的微小波动范围测量,现场控制效果良好.

  20. Extremal Hairy Black Holes

    CERN Document Server

    Gonzalez, P A; Saavedra, Joel; Vasquez, Yerko

    2014-01-01

    We consider a gravitating system consisting of a scalar field minimally coupled to gravity with a self-interacting potential and an U(1) electromagnetic field. Solving the coupled Einstein-Maxwell-scalar system we find exact hairy charged black hole solutions with the scalar field regular everywhere. We go to the zero temperature limit and we study the effect of the scalar field on the near horizon geometry of an extremal black hole. We find that except a critical value of the charge of the black hole there is also a critical value of the charge of the scalar field beyond of which the extremal black hole is destabilized. We study the thermodynamics of these solutions and we find that if the space is flat then at low temperature the Reissner-Nordstr\\"om black hole is thermodynamically preferred, while if the space is AdS the hairy charged black hole is thermodynamically preferred at low temperature.

  1. Extreme geomagnetically induced currents

    Science.gov (United States)

    Kataoka, Ryuho; Ngwira, Chigomezyo

    2016-12-01

    We propose an emergency alert framework for geomagnetically induced currents (GICs), based on the empirically extreme values and theoretical upper limits of the solar wind parameters and of d B/d t, the time derivative of magnetic field variations at ground. We expect this framework to be useful for preparing against extreme events. Our analysis is based on a review of various papers, including those presented during Extreme Space Weather Workshops held in Japan in 2011, 2012, 2013, and 2014. Large-amplitude d B/d t values are the major cause of hazards associated with three different types of GICs: (1) slow d B/d t with ring current evolution (RC-type), (2) fast d B/d t associated with auroral electrojet activity (AE-type), and (3) transient d B/d t of sudden commencements (SC-type). We set "caution," "warning," and "emergency" alert levels during the main phase of superstorms with the peak Dst index of less than -300 nT (once per 10 years), -600 nT (once per 60 years), or -900 nT (once per 100 years), respectively. The extreme d B/d t values of the AE-type GICs are 2000, 4000, and 6000 nT/min at caution, warning, and emergency levels, respectively. For the SC-type GICs, a "transient alert" is also proposed for d B/d t values of 40 nT/s at low latitudes and 110 nT/s at high latitudes, especially when the solar energetic particle flux is unusually high.

  2. Model of Credit Risk Assessment in Commercial Banks Based on Asymmetric GARCH and Extreme Value Theory%基于非对称GARCH与极值理论的商业银行信用风险度量模型

    Institute of Scientific and Technical Information of China (English)

    刘宁; 夏恩君; 张庆雷

    2012-01-01

    提出一种基于ARMA-TGARCH-EVT模型并适用于商业银行内部信用风险评估的新方法.首先通过广义矩法估计ARMA-TGARCH模型,获得近似独立同分布的残差序列zt;然后选用极值理论的越槛高峰模型(POT)对残差序列进行拟合分析,得到风险价值和期望损失的估计值,并采用Bootstrap方法给出95%置信水平下的置信区间;最后利用某商业银行2000-02-19~2010-12-15的日信贷资产对数收益率进行仿真,得到控制信用风险价值V和期望损失E值及置信区间,并与未经调整的预测值进行比较.研究结果表明,该方法在一定程度上克服了单纯进行极值分析时,由于序列的非独立同分布不能满足极值理论假设所造成的估计误差,改进了采用似然比率法估计置信区间时,由于极值事件的小样本所造成的偏差.%A new method for evaluating commercial bank's internal credit risk based on ARMA-TGARCH-EVT model is proposed. Firstly, a mixed model of ARMA-TGARCH is estimated using GMM, and then the residual series z, with properties of approximately independent and identically distribution is obtained. Secondly, the POT model of extreme value theory is employed for fitting analysis of the residual sequence to get the estimated value of VAR and ES, and the Bootstrap method is used to determine the confidence interval of VAR and ES at 95% confidence level. Finally, the data that the daily credit asset's logarithmic yields of a commercial bank from 2000-02-19 ~ 2010-12-15 are utilized to simulate the results from using this method. Simulation results indicate that, compared with the unadjusted predictive value, the proposed method could overcome the estimation error to some extent, since the sequence's non-independent-and-identically distribution could not meet the assumptions of extreme value theory. Moreover, the method could improve the deviation caused by small samples of extreme events when the likelihood ratio method is

  3. The Path of Carbon in Photosynthesis XIII. pH Effects in C{sup 14}O{sub 2} Fixation by Scenedesmus

    Science.gov (United States)

    Ouellet, C.; Benson, A. A.

    1951-10-23

    The rates of photosynthesis and dark fixation of C{sup 14}O{sub 2} in Scenedesmus have been compared in dilute phosphate buffers of 1.6 to 11.4 pH; determination of C{sup 14} incorporation into the various products shows enhancement of uptake in an acid medium into sucrose, polysaccharides, alanine and serine, in an alkaline medium into malic asparctic acids. kinetic experiments at extreme pH values suggest that several paths are available for CO{sub 2} assimilation. A tentative correlation of the results with the pH optima of some enzymes and resultant effects upon concentrations of intermediates is presented.

  4. Urinary pH and renal lithiasis.

    Science.gov (United States)

    Grases, F; Costa-Bauzá, A; Gomila, I; Ramis, M; García-Raja, A; Prieto, R M

    2012-02-01

    Formation of calcium oxalate crystals, either as monohydrate or dihydrate, is apparently unrelated to urinary pH because the solubilities of these salts are practically unaltered at physiologic urinary pH values. However, a urinary pH 6.0 may induce uric acid or calcium phosphate crystals formation, respectively, which under appropriate conditions may induce the development of the calcium oxalate calculi. We assessed the relationship between the urinary pH and the formation of different types of calculi. A retrospective study in 1,478 patients was done. We determined the composition, macrostructure, and microstructure of the calculi and the urinary pH, 50.9% of calcium oxalate monohydrate unattached calculi were present in patients with urinary pH 6.0, respectively. Infectious calculi were found primarily in patients with urinary pH >6.0 (50.7%). Only calcium oxalate monohydrate papillary calculi were associated with urinary pH between 5.5 and 6.0 (43.1%). Urine of pH 6.0 has an increased capacity to develop calcium phosphate crystals, which can act as a heterogeneous nuclei of calcium oxalate crystals. Oxalate monohydrate papillary calculi were associated to pH between 5.5 and 6.0 because the injured papilla acts as a heterogeneous nucleant. Consequently, measurement of urinary pH may be used to evaluate the lithogen risk of given urine.

  5. de Sitter Extremal Surfaces

    CERN Document Server

    Narayan, K

    2015-01-01

    We study extremal surfaces in de Sitter space in the Poincare slicing in the upper patch, anchored on spatial subregions at the future boundary ${\\cal I}^+$, restricted to constant boundary Euclidean time slices (focussing on strip subregions). We find real extremal surfaces of minimal area as the boundaries of past lightcone wedges of the subregions in question: these are null surfaces with vanishing area. We find also complex extremal surfaces as complex extrema of the area functional, and the area is not always real-valued. In $dS_4$ the area is real and has some structural resemblance with entanglement entropy in a dual $CFT_3$. There are parallels with analytic continuation from the Ryu-Takayanagi expressions for holographic entanglement entropy in $AdS$. We also discuss extremal surfaces in the $dS$ black brane and the de Sitter "bluewall" studied previously. The $dS_4$ black brane complex surfaces exhibit a real finite cutoff-independent extensive piece. In the bluewall geometry, there are real surface...

  6. pH值及盐度对副溶血弧菌与霍乱弧菌生长影响的研究%Effects of pH value and salinity on growth of Vibrio parahaemol yticus and Vibrio cholerae

    Institute of Scientific and Technical Information of China (English)

    胡兴娟; 沈飚; 张文斌

    2011-01-01

    OBJECTIVE To study the effect of different pH value and salinity of broth on the growth of Vibrio parahaemolyticus and Vibrio cholerae, and to find out the best pH value and salinity. METHODS The bacterial .counts of Vibrio cholerae and Vibrio paraheamolyticus were detected referring to international and domestic request under differrent pH ralue and salinity concerntration. RESULTS The enrichment broth pH 7. 2 and salinity 3. 2% were the most suitable condition for the growth of V. Parahaemolyticus, pH 7. 1 and salinity 1. 2% were the most suitable condition to the growth of V. Cholera. CONCLUSION pH value and salinity of enrichment broth can influence the growth of V. Parahaemolyticus and V. Cholerae.%目的 研究增菌液pH值及盐度对副溶血弧菌和霍乱弧菌生长的影响,找出副溶血弧菌与霍乱弧菌的最佳生长pH和盐度.方法 应用阳性菌株副溶血弧菌和霍乱弧菌,参照国际和国内增菌液的要求,控制增菌液pH值和盐度条件,采用弧菌显色培养基检测副溶血弧菌和霍乱弧菌生长数.结果 增菌液pH值7.2、盐度3.2%时最适副溶血弧菌生长,增菌液pH值7.1、盐度1.2%时最适霍乱弧菌生长.结论 增菌液pH值和盐度对副溶血弧菌和霍乱弧菌生长有一定影响.

  7. Effect of initial pH value in aqueous solution on direct reaction kinetics of 2,4-D with ozone%溶液初始pH值对2,4-D臭氧直接反应动力学的影响

    Institute of Scientific and Technical Information of China (English)

    陈岚; 权宇珩

    2011-01-01

    @@ 引言 目前,农药被大量研制及施用,由此带来的农药污染越来越受到人们的重视.含氯苯氧梭酸类除草剂2,4-D(2,4-二氯苯氧乙酸)是一种使用较广、应用较早的除草剂.2,4-D自然降解较慢,由于具有非挥发性和可溶性,易导致地下水或地表水污染,水体中已经可以检测到2,4-D的存在.%In order to understand the kinetics of direct oxidation between ozone molecule and 2, 4dichlorophenoxyacetic acid (2,4-D), the ozone oxidation of 2,4-D using sufficient tert-butyl alcohol as free radical inhibiting agent was studied in a bubbling reactor. The effect of initial pH on 2,4-D direct oxidation process was discussed. The results show that direct oxidation of 2,4-D and transfer of O3 are affected hy initial pH. When the value of initial pH is lower than 3.3, the solution pH value maintains approximately constant during the process. When it is larger than 3. 3, the solution pH value drops abruptly and reaches a steady value in a short period, while concentration of ozone increases rapidly and does a steady concentration. With the increasing of initial pH the steady ozone concentration and pseudo-first-order rate constant increase, and the time required to reach this steady value decreases. Hatta numbers are lower than 0.03 for different pH values. The 2, 4-D degradation process by ozone molecule follows the slow rate kinetics. It shows that the direct reaction of 2,4-D and ozone molecule is a control step of whole kinetics process.

  8. Multivalued and Multiple Reflected Raytracing with Extreme Value Based on the Multistage Modified Shortest-path Method%分区多步最短路径极值法多值多次反射波追踪

    Institute of Scientific and Technical Information of China (English)

    唐小平; 白超英; 刘宽厚

    2011-01-01

    The grid-based raytracing algorithms,such as the finite-difference eikonal equation solver and the shortest-path method,are all based on the Fermat (minimum travel time) principle, which is able to track the first reflected arrivals only. In heterogeneous media involving a relatively larger velocity contrast or complex reflected interface. The seismic wavefronts are self-intersected, as a result, the rays are multi-paths. In order to simulate such multivalued and multiple reflected arrivals, we put forward an algorithm to trace the multivalued and multiple reflected arrivals, it referred as the extreme value algorithm based on the multistage modified shortest-path method, which is capable of tracking the multivalued and multiple reflected arrivals in velocity model included complex reflected interfaces. The principles of the extreme value are that;we firstly conduct down-wind raytracing from both sources and receivers to the sampled reflected interfaces and record the traveltimes and raypaths at each sampled reflected point,and sum up traveltime value at each reflected point, and form a stacked' traveltime-distance' curve (or surface for 3D case);secondly we solve extremum values for this stacked'traveltime-distance'curveCor surface).in which the location of the extreme points are the reflected points; finally we link the raypaths and add traveltimes from the source to the reflected point,and then to the receiver. Thus the multivalued and multiple reflected arrivals are successfully traced. This algorithm has a simple principle, high accuracy, fast CPU time and easy adaptation for complex media-Compared with the fast marching method and error analysis.it is evident that the extreme value of the multistage shortest-path method is a feasible and efficient algorithm for tracking the multivalued and multiple reflected arrivals.%基于网格单元扩展的射线追踪算法,如:较为流行的有限差分解程函方程法和最短路径法均是建立在费马(最小

  9. Transcriptional control of the F0F1-ATP synthase operon of Corynebacterium glutamicum: SigmaH factor binds to its promoter and regulates its expression at different pH values.

    Science.gov (United States)

    Barriuso-Iglesias, Mónica; Barreiro, Carlos; Sola-Landa, Alberto; Martín, Juan F

    2013-03-01

    Corynebacterium glutamicum used in the amino acid fermentation industries is an alkaliphilic microorganism. Its F(0)F(1)-ATPase operon (atpBEFHAGDC) is expressed optimally at pH 9.0 forming a polycistronic (7.5 kb) and a monocistronic (1.2 kb) transcripts both starting upstream of the atpB gene. Expression of this operon is controlled by the SigmaH factor. The sigmaH gene (sigH) was cloned and shown to be co-transcribed with a small gene, cg0877, encoding a putative anti-sigma factor. A mutant deleted in the sigH gene expressed the atpBEFHAGDC operon optimally at pH 7.0 at difference of the wild-type strain (optimal expression at pH 9.0). These results suggested that the SigmaH factor is involved in pH control of expression of the F(0) F(1) ATPase operon. The SigmaH protein was expressed in Escherichia coli fused to the GST (glutathione-S-transferase) and purified to homogeneity by affinity chromatography on a GSTrap HP column. The fused protein was identified by immunodetection with anti-GST antibodies. DNA-binding studies by electrophoretic mobility shift assays showed that the SigH protein binds to a region of the atpB promoter containing the sigmaH recognition sequence (-35)TTGGAT…18nt…GTTA(-10). SigmaH plays an important role in the cascade of control of pH stress in Corynebacterium.

  10. The value of high-frequency ultrasound in application of diagnosing myocele in extremities%高频超声在诊断肢体肌疝中的应用价值探讨

    Institute of Scientific and Technical Information of China (English)

    李楠; 吕发勤; 李昶田; 唐文博

    2014-01-01

    Objective To investigate the value of high-frequency ultrasound in the application of diagnosing myocele in extremities.Methods From January 201 1 to May 201 3,The ultrasonography appearances and presentation site of myocele in 48 patients were reviewed in General Hospital of PLA. Results Of all,36 cases were observed in the unilateral lower limb (75%),4 cases of bilateral lower extremity muscle hernia,5 cases of unilateral upper extremity,and 3 cases of other sites.Among all the 48 cases,the maximum area of myocele was about 5.0 cm ×5.7 cm ×2.5 cm,and the minimum area was about 0.3 cm ×0.3 cm ×0.2 cm.The length of interrupt of muscular fasciae was 0.3 cm to 5.7 cm.All the cases can be divided into two groups according to ultrasonography:myocele with discontinuous muscular fasciae and myocele with intact muscular fasciae.Conclusions The high-frequency ultrasound is a non-invasive,cheap,and dynamic method with good reproducibility,which can clearly demonstrate the internal structure of muscular tissue,as well as the echo and discontinuity of muscular fasciae.The specificity of this method in diagnosing myocele is postive and owns great value in clinical diagnosis.%目的:探讨高频超声在肢体肌疝中的诊断价值。方法回顾性分析2010年1月至2013年5月,中国人民解放军总医院收治的48例肌疝患者的发生部位及超声声像图表现。结果48例肌疝患者中,发生于单侧下肢36例(75.0%),双侧下肢同时发生肌疝者较为少见,仅4例(8.3%),发生于单侧上肢(包含手部)5例(10.4%),发生于其他部位3例(6.3%)。48例肌疝患者中最大的疝范围5.0 cm ×5.7 cm ×2.5 cm,最小的疝范围0.3 cm ×0.3 cm ×0.2 cm,其中肌筋膜中断的长度为0.3~5.7 cm。声像图表现可分为肌筋膜中断的肌疝和肌筋膜完整的肌疝。结论高频超声可以清楚的显示肌肉内组织结构、肌筋膜的回声及连续性等情况

  11. Research on pH value and salinity of multipathogen enrichment broth for simultaneous growth of V.parahaemolyticus and V.cholera%副溶血弧菌和霍乱弧菌合检增菌液pH值和盐度的研究

    Institute of Scientific and Technical Information of China (English)

    沈飚; 胡兴娟; 汪云泉; 张文斌

    2011-01-01

    目的:研究共同增菌液pH值和盐度对副溶血弧菌和霍乱弧菌生长的影响,找出副溶血弧菌和霍乱弧菌共增菌液的最佳pH值和盐度.方法:利用副溶血性弧菌、霍乱弧菌以及杂菌对共同增菌液的pH值和盐度进行实验,通过弧菌显色平板计数验证增菌效果,从而确定两种弧菌的共同增菌液pH和盐度.结果:副溶血性弧菌和霍乱弧菌合检增菌液的最佳条件为pH8.4,盐度2.1%.结论:增菌液pH值和盐度的改变对副溶血性弧菌和霍乱弧菌生长具有一定影响.%Objective:To study the effect of different pH values and salinities of multipathogen enrichment broth on the growth of V. Parahaemolyticus and V. Cholera, and to find out the best pH value and salinity. Methods: V. Parahaemolyticus, V. Cholera and other bacteria were applied to determine the pH value and salinity, and the enrichment effect was evaluated by Vibrio chromogenic medium. Results: The enrichment broth with pH 8.4 and salinity 2.1% are the most suitable condition to V.parahaemolyticus and V. Cholera. Conclusion: pH value and salinity of enrichment broth can influence the growth of V. Parahaemolyticus and V. Cholera.

  12. 极值理论下的香港汇丰控股VaR实证分析%VaR Analysis of HSBC Holdings in Hong Kong Based on Extreme Value Theory

    Institute of Scientific and Technical Information of China (English)

    王晓辉; 庄亮亮

    2011-01-01

    极值理论可以更精确地处理金融数据的厚尾特性.选取香港上市的汇丰控股数据,运用POT方法做实证分析,对时间序列取门限值(Threshold),对超过门限的样本数据建模,极限点渐进分布服从GPD分布,估计模型参数,检验模型的合理性,并给出置信度为95%下的VaR.%Extreme value theory can describe the heavy tail characteristics of finance data more exactly.HSBC Holdings in Hong Kong as an example are took, gaven the data analysis by the method of POT as follows: chose the threshold of the data series, modelinged the sample data excess the threshold whose limit converges to the distribution of GPD, estimated parameters, test the reasonability and gave the VAR under 95% confidence level.

  13. 慢性阻塞性肺病患者呼出气冷凝液pH值的变化%Changes of pH Value of Exhaled Breath Condensate in Patients with Chronic Obstructive Pulmonary Disease

    Institute of Scientific and Technical Information of China (English)

    李晓尘; 何静雅; 胡克

    2011-01-01

    目的:探索慢性阻塞性肺病(COPD)患者呼出气冷凝液(EBC)pH的变化和EBC中CO2对pH的影响.方法:分别对20例C()PD患者和健康志愿者用自制EBC收集器收集EBC,将收集的EBC两等份,一份立即测pH值,另一份通氩气后再测pH.结果:①通氩气前后,COPD组pH均低于健康组,通氩气前两组pH分别为(6.72±0.31)、(7.62±0.23),通氩气后为(7.66±0.17)、(8.54±0.19).②通氩气后,COPD组和对照组pH均显著升高,变异率均较通氩气前小.两组pH变化值与通氩气前pH值均呈负相关(r分别为-0.946,-0.807).结论:COPD患者EBC pH明显降低.EBC中CO2可以降低EBC pH,为排除CO2对pH的影响,检测EBC pH前需预先除去EBC中的CO2.%Objective: To explore the change of exhaled breath condensate (EBC) pH of patient with chronic obstructive pulmonary disease (COPD) and the impact of CO2 on EBC pH.Methods: Twenty healthy subjects and 20 COPD patients were enrolled in this study.EBC was collected with self-made EBC collection device.Each EBC sample was divided into two aliquots.The pH of one aliquot was measured immediately, and the other was measured after bubbled with argon.Results: Before and after argon treatment respectively, the pH of COPD was lower than that of the healthy (6.72±0.31 vs 7.62±0.23, and 7.66±0.17 vs 8.54±0.19, respectively).There was a significant increase of pH in deaerated aliquot and a correlation between pre-argon and subsequent changeof pH in both COPD and healthy group (r= -0.946 and -0.807 respectively).Conclusion: There is a significant reduction of EBC pH in COPD.CO2 could decrease the pH of EBC.In order to exclude the impact of CO2 on EBC pH, deaeration is needed before the measurement of pH.

  14. Isolation and survival of Yersinia enterocolitica in ice cream at different pH values, stored at -18°c Isolamento e sobrevivência de Yersinia enterocolitica em sorvetes de distintos pH, armazenados a -18°C

    Directory of Open Access Journals (Sweden)

    Norma B. Barbini de Pederiva

    2000-09-01

    Full Text Available The presence of Yersinia enterocolitica was investigated in 203 samples of industrial (123 and non-industrial ice cream (80. Two Y. enterocolitica strains were isolated from non-industrial ice cream, which suggests the possibility of post-manufacturing contamination. One strain was typed as B:1A, O: 3,50,51; lis Xz, while the other one was biotyped as: B:1A but not serologically typed. Survival of Y. enterocolitica was investigated by inoculating nine samples of industrially manufactured ice cream to contain 20 CFU/ml of Y. enterocolitica and stored at -18°C for 480 days. The inoculated samples were classified into three different groups according to their pH (Group 1: pH 4-5; Group 2: pH 5-6 and Group 3: pH 6-7. Viability was determined by a combination of direct plating and enrichment. In Group 1, Y. enterocolitica was not detected after 150 days of storage, while in Groups 2 and 3, this microorganism was isolated until day 480 of storage. These findings suggest that the survival time of Y. enterocolitica in ice cream stored at -18°C is significantly (p Neste estudo pesquisou-se a presença de Yersinia enterocolitica em 203 amostras de sorvetes, sendo 123 de fabricação industrial e 80 de fabricação artesanal. Isolaram-se 2 cepas a partir de sorvetes artesanais, uma das quais foi caracterizada como B:1A, O:3,50, 51; lis Xz e a outra se tipificou como Y. enterocolitica B:1A mas não se tipificou sorologicamente, o que sugere uma contaminação pós processo. Em 9 dos sorvetes de fabricação industrial de distintos pH, estudou-se a sobrevivência desse microrganismo, inoculando-os com 20 UFC/ml de Y. enterocolitica, quando armazenados durante 480 dias a -18°C. Esses sorvetes, segundo seu pH, agruparam-se em: Grupo 1: pH: 4-5, Grupo 2: pH 5-6 e Grupo 3: pH: 6-7. Determinou-se a viabilidade pelas curvas de morte usando semeadura direta e enriquecimento. Nos sorvetes do grupo 1, Y. enterocolitica só foi detectada até o 150° dia de

  15. Modeling extreme risks in ecology.

    Science.gov (United States)

    Burgman, Mark; Franklin, James; Hayes, Keith R; Hosack, Geoffrey R; Peters, Gareth W; Sisson, Scott A

    2012-11-01

    Extreme risks in ecology are typified by circumstances in which data are sporadic or unavailable, understanding is poor, and decisions are urgently needed. Expert judgments are pervasive and disagreements among experts are commonplace. We outline approaches to evaluating extreme risks in ecology that rely on stochastic simulation, with a particular focus on methods to evaluate the likelihood of extinction and quasi-extinction of threatened species, and the likelihood of establishment and spread of invasive pests. We evaluate the importance of assumptions in these assessments and the potential of some new approaches to account for these uncertainties, including hierarchical estimation procedures and generalized extreme value distributions. We conclude by examining the treatment of consequences in extreme risk analysis in ecology and how expert judgment may better be harnessed to evaluate extreme risks.

  16. Effect of Clay with Different pH Values on Organophosphorus Pervasion%不同pH值黏土层对有机磷渗透的影响分析

    Institute of Scientific and Technical Information of China (English)

    宋顶峰; 李红艳; 李绪谦; 周记玲

    2011-01-01

    采用施压条件下有机磷溶液渗透通过粘性土层的实验,模拟有机磷越流通过弱透水层的过程,研究粘土层pH值不同时对有机磷渗透迁移的影响规律.分析认为,有机磷渗透通过粘性土层的能力随着土层pH值的升高而降低;pH为7.5时矿化率为98.75%,迁移率为1.25%,土层pH值≥8.5时有机磷未穿透粘土层,阻滞效果明显.矿化形成的PO4离子占总磷的百分比随着土层pH值的升高而增加,与Ca+离子结合形成沉淀物的能力增强,粘土pH值的升高对有机磷的降解转化具有明显的促进作用.%Organophosphor was put on pressure to permeate the cohesive soil in this experiment, for simulating the process of organophosphor leakage permeating the aquitard, in order to explore the influence of clayey pH on pervasion and migration of organophosphorus. The findings show that pervasive ability of organophosphorus fall with the rise of clayey pH, mineralization rate is 98.75% and migrating rate is 1.25% when pH is 7.5. Organophosphorus can not permeate the clay when pH ≥8.5 and retardation of clay on organophosphor is obvious. The proportion of PO43- contributing to TP will raise with pH of clay, and the ability of forming precipitate with Ca2+ enhance also. The rise of clayey pH has the obvious advance on the degradation and conversion of organophosphorus.

  17. Extremal periodic wave profiles

    Directory of Open Access Journals (Sweden)

    E. van Groesen

    2007-01-01

    Full Text Available As a contribution to deterministic investigations into extreme fluid surface waves, in this paper wave profiles of prescribed period that have maximal crest height will be investigated. As constraints the values of the momentum and energy integrals are used in a simplified description with the KdV model. The result is that at the boundary of the feasible region in the momentum-energy plane, the only possible profiles are the well known cnoidal wave profiles. Inside the feasible region the extremal profiles of maximal crest height are "cornered" cnoidal profiles: cnoidal profiles of larger period, cut-off and periodically continued with the prescribed period so that at the maximal crest height a corner results.

  18. Influence of pH value and slow granule on HA/TiO2 coatings deposited by hydrothermal-electrochemical method%pH 值和缓冲剂对水热电化学沉积 HA/TiO 2涂层的影响

    Institute of Scientific and Technical Information of China (English)

    马凤仓; 徐敏; 刘平; 李伟; 刘新宽; 何代华; 陆晓琴

    2014-01-01

    Using titanium alloy after micro-arc oxidation as substrate,HA/TiO 2 coatings were prepared by hy-drothermal-electrochemical method.The morphologies and phase compositions of coatings were characterized by means of SEM and XRD,and the variation of pH value of electrode/electrolyte was measured by means of pH microprobe;in this way,the influences of pH value and slow granule on HA/TiO 2 coatings deposited by hydro-thermal-electrochemical method were investigated.The results show that micro-arc oxidation coatings contrib-ute to HA deposited by hydrothermal-electrochemical method and HA crystals are well-distributed and densified in the coatings.When the pH value was within the range of 2 to 8,the increasing of the pH value contributes to HA crystals with high crystallinity and the growth of HA along the crystallographic plane (002).During the process of depositing HA by hydrothermal-electrochemical method ,pH value on the surface of electrode increa-ses at first and then decreases with the deposition time,while pH value of electrolyte decreases with the deposi-tion time.pH value and slow granule have obvious influences on the morphologies of HA crystals.HA crystals prepared in the electrolyte containing slow granule are rods in shape,the edge face of rod was a defined flat hex-agon and the surface of the crystal was smooth,and HA crystals are well-crystallized.%以微弧氧化后的钛合金为基体,采用水热电化学法制备了 HA/TiO 2涂层.利用 SEM、XRD 对涂层的表面形貌、物相组成进行了表征分析,通过 pH 微探针原位探测电极/电解液界面 pH 值的变化,研究了pH 值和缓冲剂对水热电化学沉积 HA/TiO 2涂层的影响.研究结果表明,微弧氧化膜有利于水热电化学沉积 HA,得到的 HA 晶体分布均匀、致密.当电解液pH 值在2~8时,pH 值升高有利于提高水热电化学沉积 HA 的结晶度,并促使 HA 沿(002)晶面生长.在水热电化学沉积 HA 过程中,电极表面的 pH 值随沉

  19. Statistical Model of Extreme Shear

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Hansen, Kurt Schaldemose

    2004-01-01

    In order to continue cost-optimisation of modern large wind turbines, it is important to continously increase the knowledge on wind field parameters relevant to design loads. This paper presents a general statistical model that offers site-specific prediction of the probability density function...... by a model that, on a statistically consistent basis, describe the most likely spatial shape of an extreme wind shear event. Predictions from the model have been compared with results from an extreme value data analysis, based on a large number of high-sampled full-scale time series measurements...... are consistent, given the inevitabel uncertainties associated with model as well as with the extreme value data analysis. Keywords: Statistical model, extreme wind conditions, statistical analysis, turbulence, wind loading, statistical analysis, turbulence, wind loading, wind shear, wind turbines....

  20. Effects on results of occult blood test in gastric juice at different pH