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1.
Saulis G Lape R Praneviciūte R Mickevicius D 《Bioelectrochemistry (Amsterdam, Netherlands)》2005,67(1):101-108
The change of the pH of a NaCl solution (139-149 mM NaCl) buffered with 5-15 mM sodium phosphates (pH 7.4) during electromanipulation was studied. It has been determined that an increase in the pH value of electroporation solution of a whole chamber volume, caused by the application of electric field pulses, commonly used in cell electromanipulation procedures, can exceed 1-2 pH units. Several materials for the cathode were tested. In all cases a stainless steel anode was utilized. The aluminum cathode gave a two-fold greater DeltapH in comparison with platinum, copper or stainless steel cathodes. In addition, a substantial release of aluminum (up to 1 mg/l) from the cathode was observed. It has also been found that the shift in pH depended on the medium conductivity: DeltapH of the solution, in which sucrose was substituted for NaCl, was about 5 times less. On the basis of the results obtained here, to avoid the plausible undesirable consequences of the cathodic electrolysis processes, in particular under the conditions of strong electric treatment, it could be recommended that chambers with aluminum electrodes not be utilized and one should use strongly buffered solutions of low conductivity and alternating current (sine or square wave) bipolar electric pulses. 相似文献
2.
Superbasic Alkyl‐Substituted Bisphosphazene Proton Sponges: Synthesis,Structural Features,Thermodynamic and Kinetic Basicity,Nucleophilicity and Coordination Chemistry
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3.
We study limit distribution of partial sums SN,k(t) =
s = 1
[N t]
Ak(Xs) of Appell polynomials of the long-range dependent moving average process Xt> = i t bt - i i, where {i} is a strictly stationary and weakly dependent martingale difference sequence, and bi id - 1 (0 < d < 1/2). We show that if k(1-2 d)<1, then suitably normalized partial sums SN,k(t) converge in distribution to the kth order Hermite process. This result generalizes the corresponding results of Surgailis, and Avram and Taqqu obtained in the case of the i.i.d. sequence { i}. 相似文献
4.
We construct a two-sample test for comparison of long memory parameters based on ratios of two rescaled variance (V/S) statistics studied in Giraitis et al. [L. Giraitis, R. Leipus, A. Philippe, A test for stationarity versus trends and unit roots for a wide class of dependent errors, Econometric Theory 21 (2006) 989-1029]. The two samples have the same length and can be mutually independent or dependent. In the latter case, the test statistic is modified to make it asymptotically free of the long-run correlation coefficient between the samples. To diminish the sensitivity of the test on the choice of the bandwidth parameter, an adaptive formula for the bandwidth parameter is derived using the asymptotic expansion in Abadir et al. [K. Abadir, W. Distaso, L. Giraitis, Two estimators of the long-run variance: beyond short memory, Journal of Econometrics 150 (2009) 56-70]. A simulation study shows that the above choice of bandwidth leads to a good size of our comparison test for most values of fractional and ARMA parameters of the simulated series. 相似文献
5.
A new nonparametric estimator of the local Hurst function of a multifractional Gaussian process based on the increment ratio (IR) statistic is defined. In a general frame, the point-wise and uniform weak and strong consistency and a multidimensional central limit theorem for this estimator are established. Similar results are obtained for a refinement of the generalized quadratic variations (QV) estimator. The example of the multifractional Brownian motion is studied in detail. A simulation study is included showing that the IR-estimator is more accurate than the QV-estimator. 相似文献
6.
Antonovič Valentin Sikarskas Donatas Malaiškienė Jurgita Boris Renata Stonys Rimvydas 《Journal of Thermal Analysis and Calorimetry》2019,138(6):4127-4137
Journal of Thermal Analysis and Calorimetry - The article analyses the peculiarities of the combined effect on hydration process of the following pozzolanic additives: metakaolin waste (MW),... 相似文献
7.
Donatas Surgailis Gilles Teyssière Marijus Vai?iulis 《Journal of multivariate analysis》2008,99(3):510-541
We introduce a new statistic written as a sum of certain ratios of second-order increments of partial sums process of observations, which we call the increment ratio (IR) statistic. The IR statistic can be used for testing nonparametric hypotheses for d-integrated () behavior of time series Xt, including short memory (d=0), (stationary) long-memory and unit roots (d=1). If Sn behaves asymptotically as an (integrated) fractional Brownian motion with parameter , the IR statistic converges to a monotone function Λ(d) of as both the sample size N and the window parameter m increase so that N/m→∞. For Gaussian observations Xt, we obtain a rate of decay of the bias EIR-Λ(d) and a central limit theorem (N/m)1/2(IR-EIR)→N(0,σ2(d)), in the region . Graphs of the functions Λ(d) and σ(d) are included. A simulation study shows that the IR test for short memory (d=0) against stationary long-memory alternatives has good size and power properties and is robust against changes in mean, slowly varying trends and nonstationarities. We apply this statistic to sequences of squares of returns on financial assets and obtain a nuanced picture of the presence of long-memory in asset price volatility. 相似文献
8.
We prove a functional central limit theorem for the partial sums of a class of time varying processes with long memory. To cite this article: A. Philippe et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
9.
Donatas Butkus Audrius Gagiškis Erika Streckytė Raimondas Grubliauskas 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):1085-1092
The physical and chemical characteristics of radon gas make it a good tracer for use in the application of atmospheric transport models. Radon exhalation rate from soil is one of the most important factors for evaluation of the environmental radon level. For this purpose to find out the volumetric activity of radon in ground-level air the measuring has been made using radon monitor SARAD RTM 2200. Radon volumetric activity and radon exhalation rate in ground-level air and at different depths of soil depending on soil temperature and atmospheric parameters in different seasons of the year was calculated and evaluated in two areas of Vilnius city. It has been established that the volumetric activity of radon and radon exhalation intensity is vertically distributed and the corresponding increase in deeper soil layers, and depends on the specific activity of radium, soil temperature and moisture content, temperature difference between soil and atmospheric temperatures. 相似文献
10.
Liudas Giraitis Donatas Surgailis 《Stochastic Processes and their Applications》2002,100(1-2):275-300
We discuss the covariance structure and long-memory properties of stationary solutions of the bilinear equation Xt=ζtAt+Bt,(), where
are standard i.i.d. r.v.'s, and At,Bt are moving averages in Xs, s<t. Stationary solution of () is obtained as an orthogonal Volterra expansion. In the case At≡1, Xt is the classical AR(∞) process, while Bt≡0 gives the LARCH model studied by Giraitis et al. (Ann. Appl. Probab. 10 (2000) 1002). In the general case, Xt may exhibit long memory both in conditional mean and in conditional variance, with arbitrary fractional parameters
and
, respectively. We also discuss the hyperbolic decay of auto- and/or cross-covariances of Xt and Xt2 and the asymptotic distribution of the corresponding partial sums’ processes. 相似文献