Articoli di riviste: "Weakly dependent process"

1

Bertin, Karine, e Nicolas Klutchnikoff. "Pointwise adaptive estimation of the marginal density of a weakly dependent process". Journal of Statistical Planning and Inference 187 (agosto 2017): 115–29. http://dx.doi.org/10.1016/j.jspi.2017.03.003.

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2

Pang, Guodong, e Yuhang Zhou. "Functional Limit Theorems for Shot Noise Processes with Weakly Dependent Noises". Stochastic Systems 10, n. 2 (giugno 2020): 99–123. http://dx.doi.org/10.1287/stsy.2019.0051.

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Abstract (sommario):

We study shot noise processes when the shot noises are weakly dependent, satisfying the ρ-mixing condition. We prove a functional weak law of large numbers and a functional central limit theorem for this shot noise process in an asymptotic regime with a high intensity of shots. The deterministic fluid limit is unaffected by the presence of weak dependence. The limit in the diffusion scale is a continuous Gaussian process whose covariance function explicitly captures the dependence among the noises. The model and results can be applied in financial and insurance risks with dependent claims as well as queueing systems with dependent service times. To prove the existence of the limit process, we employ the existence criterion that uses a maximal inequality requiring a set function with a superadditivity property. We identify such a set function for the limit process by exploiting the ρ-mixing condition. To prove the weak convergence, we establish the tightness property and the convergence of finite dimensional distributions. To prove tightness, we construct two auxiliary processes and apply an Ottaviani-type inequality for weakly dependent sequences.

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3

Chahad, Abdelkader, e Mohammed Bassoudi. "Nonparametric estimation of P(X<Y) using local linear methods for weakly dependent data". STUDIES IN ENGINEERING AND EXACT SCIENCES 5, n. 2 (16 ottobre 2024): e9282. http://dx.doi.org/10.54021/seesv5n2-348.

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This study addresses the problem of accurately estimating P(X<Y), particularly in the presence of weakly dependent data. Traditional nonparametric methods often assume independence between observations, which can lead to biased results in dependent settings. To overcome this limitation, we propose the use of local linear methods for the nonparametric estimation of P(X<Y), focusing on weakly dependent data modeled using an autoregressive (AR(1)) process. The primary objective is to assess the performance of the local linear estimator under both independent and weakly dependent conditions, comparing bias, variance, and mean squared error (MSE). A Monte Carlo simulation with 1000 repetitions was conducted, utilizing large sample sizes to ensure robust asymptotic properties. Results show that while the estimator performs well for independent data, with low bias and variance, its accuracy decreases significantly in the presence of weak dependence, leading to increased prejudice and MSE. These findings highlight the need for adjustments in nonparametric methods when dealing with dependent data. In conclusion, while effective for independent cases, the local linear method demonstrates limitations when applied to weakly dependent data, emphasizing the importance of considering dependence structures in future nonparametric estimations.

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4

Künsch, H. "Discrimination between monotonic trends and long-range dependence". Journal of Applied Probability 23, n. 4 (dicembre 1986): 1025–30. http://dx.doi.org/10.2307/3214476.

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We show that the periodogram behaves differently for a weakly dependent process with a small monotonic trend and a stationary strongly dependent process. In the former case it has a non-central -distribution with noncentrality parameter tending to 0 uniformly outside intervals . In the latter case it has λα −1 times a central -distribution, 0 < α < 1.

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5

Künsch, H. "Discrimination between monotonic trends and long-range dependence". Journal of Applied Probability 23, n. 04 (dicembre 1986): 1025–30. http://dx.doi.org/10.1017/s0021900200115955.

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Abstract (sommario):

We show that the periodogram behaves differently for a weakly dependent process with a small monotonic trend and a stationary strongly dependent process. In the former case it has a non-central-distribution with noncentrality parameter tending to 0 uniformly outside intervals. In the latter case it has λα−1times a central-distribution, 0 <α< 1.

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6

Künsch, H. "Discrimination between monotonic trends and long-range dependence". Journal of Applied Probability 23, n. 04 (dicembre 1986): 1025–30. http://dx.doi.org/10.1017/s0021900200118819.

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Abstract (sommario):

We show that the periodogram behaves differently for a weakly dependent process with a small monotonic trend and a stationary strongly dependent process. In the former case it has a non-central -distribution with noncentrality parameter tending to 0 uniformly outside intervals . In the latter case it has λ α −1 times a central -distribution, 0 < α < 1.

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7

Davis, Richard A., e Tailen Hsing. "Point Process and Partial Sum Convergence for Weakly Dependent Random Variables with Infinite Variance". Annals of Probability 23, n. 2 (aprile 1995): 879–917. http://dx.doi.org/10.1214/aop/1176988294.

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8

Wieczorek, Barbara. "Blockwise bootstrap of the estimated empirical process based on $$\psi $$ ψ -weakly dependent observations". Statistical Inference for Stochastic Processes 19, n. 1 (13 giugno 2015): 111–29. http://dx.doi.org/10.1007/s11203-015-9120-2.

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9

KO, MI-HWA, HYUN-CHULL KIM e TAE-SUNG KIM. "ON FUNCTIONAL CENTRAL LIMIT THEOREMS FOR LINEAR RANDOM FIELDS WITH DEPENDENT INNOVATIONS". ANZIAM Journal 49, n. 4 (aprile 2008): 533–41. http://dx.doi.org/10.1017/s1446181108000217.

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AbstractFor a linear random field (linear p-parameter stochastic process) generated by a dependent random field with zero mean and finite qth moments (q>2p), we give sufficient conditions that the linear random field converges weakly to a multiparameter standard Brownian motion if the corresponding dependent random field does so.

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10

Bondarenko, S., e K. Komoshvili. "Transverse transport properties of a charged drop in an electric field". International Journal of Modern Physics E 24, n. 05 (maggio 2015): 1550034. http://dx.doi.org/10.1142/s0218301315500342.

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Transport properties of a charged droplet of weakly interacting particles in transverse electric field are investigated. Nonequilibrium, time-dependent distribution function which describes a process of the droplet transverse evolution with constant entropy in the field is calculated. With the help of this distribution function, shear viscosity coefficients in the transverse plane are calculated as well. They are found to be dependent on the ratio of the potential energy of the droplet in the electric field to the kinetic energy of the droplet; for weakly interacting particles, this parameter is small. Additionally, these coefficients are time-dependent and change during the hydrodynamical state of the droplet's expansion. Applicability of the results to the description of initial states of quark–gluon plasma (QGP) obtained in high-energy interactions of nuclei is also discussed.

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11

Jensen, Jens Ledet. "Asymptotic normality of M-estimators in nonhomogeneous hidden Markov models". Journal of Applied Probability 48, A (agosto 2011): 295–306. http://dx.doi.org/10.1239/jap/1318940472.

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Results on asymptotic normality for the maximum likelihood estimate in hidden Markov models are extended in two directions. The stationarity assumption is relaxed, which allows for a covariate process influencing the hidden Markov process. Furthermore, a class of estimating equations is considered instead of the maximum likelihood estimate. The basic ingredients are mixing properties of the process and a general central limit theorem for weakly dependent variables.

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Jensen, Jens Ledet. "Asymptotic normality of M-estimators in nonhomogeneous hidden Markov models". Journal of Applied Probability 48, A (agosto 2011): 295–306. http://dx.doi.org/10.1017/s0021900200099290.

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Results on asymptotic normality for the maximum likelihood estimate in hidden Markov models are extended in two directions. The stationarity assumption is relaxed, which allows for a covariate process influencing the hidden Markov process. Furthermore, a class of estimating equations is considered instead of the maximum likelihood estimate. The basic ingredients are mixing properties of the process and a general central limit theorem for weakly dependent variables.

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13

Lee, Seokjin, Minhan Kim, Seunghyeon Shin, Sooyoung Park e Youngho Jeong. "Data-Dependent Feature Extraction Method Based on Non-Negative Matrix Factorization for Weakly Supervised Domestic Sound Event Detection". Applied Sciences 11, n. 3 (24 gennaio 2021): 1040. http://dx.doi.org/10.3390/app11031040.

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In this paper, feature extraction methods are developed based on the non-negative matrix factorization (NMF) algorithm to be applied in weakly supervised sound event detection. Recently, the development of various features and systems have been attempted to tackle the problems of acoustic scene classification and sound event detection. However, most of these systems use data-independent spectral features, e.g., Mel-spectrogram, log-Mel-spectrum, and gammatone filterbank. Some data-dependent feature extraction methods, including the NMF-based methods, recently demonstrated the potential to tackle the problems mentioned above for long-term acoustic signals. In this paper, we further develop the recently proposed NMF-based feature extraction method to enable its application in weakly supervised sound event detection. To achieve this goal, we develop a strategy for training the frequency basis matrix using a heterogeneous database consisting of strongly- and weakly-labeled data. Moreover, we develop a non-iterative version of the NMF-based feature extraction method so that the proposed feature extraction method can be applied as a part of the model structure similar to the modern “on-the-fly” transform method for the Mel-spectrogram. To detect the sound events, the temporal basis is calculated using the NMF method and then used as a feature for the mean-teacher-model-based classifier. The results are improved for the event-wise post-processing method. To evaluate the proposed system, simulations of the weakly supervised sound event detection were conducted using the Detection and Classification of Acoustic Scenes and Events 2020 Task 4 database. The results reveal that the proposed system has F1-score performance comparable with the Mel-spectrogram and gammatonegram and exhibits 3–5% better performance than the log-Mel-spectrum and constant-Q transform.

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14

Glynn, Peter W. "On exponential limit laws for hitting times of rare sets for Harris chains and processes". Journal of Applied Probability 48, A (agosto 2011): 319–26. http://dx.doi.org/10.1239/jap/1318940474.

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This paper provides a simple proof for the fact that the hitting time to an infrequently visited subset for a one-dependent regenerative process converges weakly to an exponential distribution. Special cases are positive recurrent Harris chains and Harris processes. The paper further extends this class of limit theorems to ‘rewards’ that are cumulated to the hitting time of such a rare set.

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15

Glynn, Peter W. "On exponential limit laws for hitting times of rare sets for Harris chains and processes". Journal of Applied Probability 48, A (agosto 2011): 319–26. http://dx.doi.org/10.1017/s0021900200099319.

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This paper provides a simple proof for the fact that the hitting time to an infrequently visited subset for a one-dependent regenerative process converges weakly to an exponential distribution. Special cases are positive recurrent Harris chains and Harris processes. The paper further extends this class of limit theorems to ‘rewards’ that are cumulated to the hitting time of such a rare set.

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16

Hidalgo, J., e Y. Yajima. "PREDICTION AND SIGNAL EXTRACTION OF STRONGLY DEPENDENT PROCESSES IN THE FREQUENCY DOMAIN". Econometric Theory 18, n. 3 (15 maggio 2002): 584–624. http://dx.doi.org/10.1017/s0266466602183022.

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We frequently observe that one of the aims of time series analysts is to predict future values of the data. For weakly dependent data, when the model is known up to a finite set of parameters, its statistical properties are well documented and exhaustively examined. However, if the model was misspecified, the predictors would no longer be correct. Motivated by this observation and because of the interest in obtaining adequate and reliable predictors, Bhansali (1974, Journal of the Royal Statistical Society, Series B 36, 61–73) examined the properties of a nonparametric predictor based on the canonical factorization of the spectral density function given in Whittle (1963, Prediction and Regulation by Linear Least Squares) and known as FLES.However, the preceding work does not cover the so-called strongly dependent data. Because of the interest in this type of processes, one of our objectives in this paper is to examine the properties of the FLES for these processes. In addition, we illustrate how the FLES can be adapted to recover the signal of a strongly dependent process, showing its consistency. The proposed method is semiparametric in the sense that, in contrast to other methods, we do not need to assume any particular model for the noise except that it is weakly dependent.

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17

Zhang, Chenbo, Yinglu Zhang, Lu Zhang, Jiajia Zhao, Jihong Guan e Shuigeng Zhou. "Weakly Supervised Few-Shot Object Detection with DETR". Proceedings of the AAAI Conference on Artificial Intelligence 38, n. 7 (24 marzo 2024): 7015–23. http://dx.doi.org/10.1609/aaai.v38i7.28528.

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In recent years, Few-shot Object Detection (FSOD) has become an increasingly important research topic in computer vision. However, existing FSOD methods require strong annotations including category labels and bounding boxes, and their performance is heavily dependent on the quality of box annotations. However, acquiring strong annotations is both expensive and time-consuming. This inspires the study on weakly supervised FSOD (WS-FSOD in short), which realizes FSOD with only image-level annotations, i.e., category labels. In this paper, we propose a new and effective weakly supervised FSOD method named WFS-DETR. By a well-designed pretraining process, WFS-DETR first acquires general object localization and integrity judgment capabilities on large-scale pretraining data. Then, it introduces object integrity into multiple-instance learning to solve the common local optimum problem by comprehensively exploiting both semantic and visual information. Finally, with simple fine-tuning, it transfers the knowledge learned from the base classes to the novel classes, which enables accurate detection of novel objects. Benefiting from this ``pretraining-refinement'' mechanism, WSF-DETR can achieve good generalization on different datasets. Extensive experiments also show that the proposed method clearly outperforms the existing counterparts in the WS-FSOD task.

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18

Mary, Anija, e Senoy Thomas. "Thickness-dependent evolution of magnetization reversal in coupled permalloy nanocaps". Physica Scripta 99, n. 10 (5 settembre 2024): 105946. http://dx.doi.org/10.1088/1402-4896/ad7334.

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Abstract The magnetization reversal mechanisms in permalloy (Py) nanocaps, coupled through an indirect exchange interaction, were investigated using micromagnetic simulations. This indirect exchange interaction can oscillate between ferromagnetic and antiferromagnetic types, depending on the thickness of the metallic interlayer. In ferromagnetically coupled Py nanocaps, coordinated nucleation and annihilation of magnetic vortices were observed. On the other hand, antiferromagnetically coupled caps exhibited a coherent rotation of spins, stabilizing a double onion state at remanence. The study also investigated the impact of nanocap thickness on the magnetization reversal process. As the thickness of the Py cap increased, the magnetization reversal displayed characteristics typical of a weakly coupled system. This shift in magnetization reversal behavior is attributed to the relative decrease in exchange coupling strength between the nanocaps as their thickness increases.

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19

Voitenko, Y., e J. De Keyser. "Turbulent spectra and spectral kinks in the transition range from MHD to kinetic Alfvén turbulence". Nonlinear Processes in Geophysics 18, n. 5 (13 settembre 2011): 587–97. http://dx.doi.org/10.5194/npg-18-587-2011.

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Abstract. A weakly dispersive range (WDR) of kinetic Alfvén turbulence is identified and investigated for the first time in the context of the MHD/kinetic turbulence transition. We find perpendicular wavenumber spectra &propto; k&bot;−3 and &propto; k&bot;−4 formed in WDR by strong and weak turbulence of kinetic Alfvén waves (KAWs), respectively. These steep WDR spectra connect shallower spectra in the MHD and strongly dispersive KAW ranges, which results in a specific double-kink (2-k) pattern often seen in observed turbulent spectra. The first kink occurs where MHD turbulence transforms into weakly dispersive KAW turbulence; the second one is between weakly and strongly dispersive KAW ranges. Our analysis suggests that partial turbulence dissipation due to amplitude-dependent non-adiabatic ion heating may occur in the vicinity of the first spectral kink. The threshold-like nature of this process results in a conditional selective dissipation that affects only the largest over-threshold amplitudes and that decreases the intermittency in the range below the first spectral kink. Several recent counter-intuitive observational findings can be explained by the coupling between such a selective dissipation and the nonlinear interaction among weakly dispersive KAWs.

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20

Eaton, William W., Marvin Mengel, Lynn Mengel, David Larson, Ross Campbell e Ruth B. Montague. "Psychosocial and Psychopathologic Influences on Management and Control of Insulin-Dependent Diabetes". International Journal of Psychiatry in Medicine 22, n. 2 (giugno 1992): 105–17. http://dx.doi.org/10.2190/df4h-9hqw-njec-q54e.

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The objective of this research was to explore the relationship of psychosocial variables to management and control of insulin-dependent diabetes, as measured by a scale of reported behavioral adherence and by glycosylated hemoglobin, respectively. The method includes a relatively large sample (127 subjects) drawn from a clinic, a broad range of psychosocial variables (depression, anxiety, family process, health locus of control), and documented reliability and validity of psychosocial measurement (alpha coefficients ranging from .63 to .95). The results show that both anxiety and depression have weak positive correlations with blood sugar. Family process variables also are weakly correlated with blood sugar. The measure of behavioral adherence is moderately correlated with blood sugar. The life stage of the diabetic appears to affect these relationships markedly. The conclusion is that there is no broad strong association of psychosocial variables with blood sugar but that there may be subgroups of diabetics, especially adolescents with recent onset, for whom the relationships may be more powerful.

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21

Barber, Kevin N., Cory K. Perkins e Allen W. Apblett. "Reduction of chromate by molybdenum hydrogen bronze". Canadian Journal of Chemistry 94, n. 4 (aprile 2016): 401–5. http://dx.doi.org/10.1139/cjc-2015-0381.

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Molybdenum hydrogen bronze, H0.57MoO3, is capable of removing up to 80 mequiv./g chromate from aqueous solution. The redox process is accompanied by adsorption of the reduced chromium species so that the chromium is completely removed from solution. Chromate removal was only weakly dependent on pH, being slightly favored at acidic pH. The kinetics appear to involve the rapid adsorption of chromate in an equilibrium process that is followed by reduction of the chromium(VI). The rate constant was found to be first order in chromate and the amount of suspended H0.57MoO3 with a rate constant of 1.40 L g−1 min−1.

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22

Chan, Terence. "Large deviations and quasi-stationarity for density-dependent birth-death processes". Journal of the Australian Mathematical Society. Series B. Applied Mathematics 40, n. 2 (ottobre 1998): 238–56. http://dx.doi.org/10.1017/s0334270000012492.

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AbstractConsider a density-dependent birth-death process XN on a finite state space of size N. Let PN be the law (on D([0, T]) where T > 0 is arbitrary) of the density process XN/N and let πN be the unique stationary distribution (on[0,1]) of XN/N, if it exists. Typically, these distributions converge weakly to a degenerate distribution as N → ∞ so the probability of sets not containing the degenerate point will tend to 0; large deviations is concerned with obtaining the exponential decay rate of these probabilities. Friedlin-Wentzel theory is used to establish the large deviations behaviour (as N → ∞) of PN. In the one-dimensional case, a large deviations principle for the stationary distribution πN is obtained by elementary explicit computations. However, when the birth-death process has an absorbing state at 0 (so πN no longer exists), the same elementary computations are still applicable to the quasi-stationary distribution, and we show that the quasi-stationary distributions obey the same large deviations principle as in the recurrent case. In addition, we address some questions related to the estimated time to absorption and obtain a large deviations principle for the invariant distribution in higher dimensions by studying a quasi-potential.

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23

Li, Zhen Yu, e Shuang Hu. "Removal of Hexavalent Chromium from Aqueous Solutions by Ion-Exchange Resin". Advanced Materials Research 550-553 (luglio 2012): 2333–37. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.2333.

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The adsorption of hexavalent chromium [Cr(VI)] from aqueous solutions using weakly basic ion-exchange resin D301 was studied in this work. The result showed that the adsorption of Cr(VI) was strongly dependent on pH, the optimum condition was investigated at pH 2 and the maximum adsorption capacity was 247.71 mg g-1. The equilibrium datas were ﬁtted well with Langmuir and Redlich–Peterson isotherm models. The pseudo-second-order rate equation was best represented by the adsorption process.

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Bertrand, Pascale, Marceline Côté, Yi-Min Zheng, Lorraine M. Albritton e Shan-Lu Liu. "Jaagsiekte Sheep Retrovirus Utilizes a pH-Dependent Endocytosis Pathway for Entry". Journal of Virology 82, n. 5 (19 dicembre 2007): 2555–59. http://dx.doi.org/10.1128/jvi.01853-07.

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ABSTRACT Using Moloney murine leukemia virus pseudovirions bearing the envelope protein of Jaagsiekte sheep retrovirus (JSRV), we report here that entry was weakly inhibited by lysosomotropic agents but was profoundly blocked by bafilomycin A1 (BafA1). Kinetics studies revealed that JSRV entry is a slow process and was substantially blocked by a dominant-negative mutant of dynamin. Interestingly, a low-pH pulse overcame the BafA1 block to JSRV infection, although this occurred only if virus-bound cells were preincubated at 37°C, consistent with a very early entry event such as endocytosis being required before the low-pH-dependent step occurs. Moreover, JSRV pseudovirions were resistant to low-pH inactivation. Altogether, this study reveals that JSRV utilizes a pH-dependent, dynamin-associated endocytosis pathway for entry that differs from the classical pH-dependent entry pathway of vesicular stomatitis virus.

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Qiu, F. S., W. J. Liu, Y. H. Chen e D. F. Zhao. "A Cohesion Metric for Design of Task Based on Activity Relationship Matrix in Product Process". Applied Mechanics and Materials 10-12 (dicembre 2007): 187–92. http://dx.doi.org/10.4028/www.scientific.net/amm.10-12.187.

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For process assignment that is strongly cohesive and weakly coupled, an evaluating model based on activity relation matrix is constructed on the similarities between software programs and the process. In this model, activity relationship matrix is employed to describe constraint-dependent relationships among activities, and this matrix is presented for calculating the numbers of controlling elements to improve the efficiency and rate of getting cohesion coefficients. In additional, the inspiration for the introduced notion is derived from cohesion metrics in software engineering. Also, a heuristic qualitative analysis method is provided that is based on this model to decide between various process assignment alternatives. Both a theoretical and an empirical evaluating method give a positive support its soundness. Lastly, several examples are given to verify the feasibility and effectiveness of the model.

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Qian, Rui, Yunchao Wei, Honghui Shi, Jiachen Li, Jiaying Liu e Thomas Huang. "Weakly Supervised Scene Parsing with Point-Based Distance Metric Learning". Proceedings of the AAAI Conference on Artificial Intelligence 33 (17 luglio 2019): 8843–50. http://dx.doi.org/10.1609/aaai.v33i01.33018843.

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Semantic scene parsing is suffering from the fact that pixellevel annotations are hard to be collected. To tackle this issue, we propose a Point-based Distance Metric Learning (PDML) in this paper. PDML does not require dense annotated masks and only leverages several labeled points that are much easier to obtain to guide the training process. Concretely, we leverage semantic relationship among the annotated points by encouraging the feature representations of the intra- and intercategory points to keep consistent, i.e. points within the same category should have more similar feature representations compared to those from different categories. We formulate such a characteristic into a simple distance metric loss, which collaborates with the point-wise cross-entropy loss to optimize the deep neural networks. Furthermore, to fully exploit the limited annotations, distance metric learning is conducted across different training images instead of simply adopting an image-dependent manner. We conduct extensive experiments on two challenging scene parsing benchmarks of PASCALContext and ADE 20K to validate the effectiveness of our PDML, and competitive mIoU scores are achieved.

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Goffman, Vladimir G., Alexander V. Gorokhovsky, Anna D. Makarova, Elena V. Tretyachenko, Mariya A. Vikulova, Alexey M. Bainyashev, Elena V. Kolokolova e Tatiana S. Teliukova. "Impedance spectroscopy of modified potassium titanates. I". Electrochemical Energetics 22, n. 2 (28 ottobre 2022): 61–69. http://dx.doi.org/10.18500/1608-4039-2022-22-2-61-69.

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The electrochemical and electrophysical properties of the protonated and modified with silver iodide potassium titanates, which can be applied in energy storage units, have been investigated by impedance spectroscopy. It has been shown that the dielectric losses at medium and high frequencies are weakly dependent on the polarizing voltage. It has also been established that transfer in modified potassium titanate can be made through potassium and silver ions. The equivalent scheme of the process has been proposed and the magnitudes of the Warburg impedances have been calculated.

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Colombini, Marco, Patrick Liu e Chase Dee. "Triplin: Mechanistic Basis for Voltage Gating". International Journal of Molecular Sciences 24, n. 14 (14 luglio 2023): 11473. http://dx.doi.org/10.3390/ijms241411473.

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The outer membrane of Gram-negative bacteria contains a variety of pore-forming structures collectively referred to as porins. Some of these are voltage dependent, but weakly so, closing at high voltages. Triplin, a novel bacterial pore-former, is a three-pore structure, highly voltage dependent, with a complex gating process. The three pores close sequentially: pore 1 at positive potentials, 2 at negative and 3 at positive. A positive domain containing 14 positive charges (the voltage sensor) translocates through the membrane during the closing process, and the translocation is proposed to take place by the domain entering the pore and thus blocking it, resulting in the closed conformation. This mechanism of pore closure is supported by kinetic measurements that show that in the closing process the voltage sensor travels through most of the transmembrane voltage before reaching the energy barrier. Voltage-dependent blockage of the pores by polyarginine, but not by a 500-fold higher concentrations of polylysine, is consistent with the model of pore closure, with the sensor consisting mainly of arginine residues, and with the presence, in each pore, of a complementary surface that serves as a binding site for the sensor.

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Krasin, George K., Yulia S. Gulina, Evgeny V. Kuzmin, Victor P. Martovitskii e Sergey I. Kudryashov. "Polarization-Sensitive Nonlinear Optical Interaction of Ultrashort Laser Pulses with HPHT Diamond". Photonics 10, n. 2 (19 gennaio 2023): 106. http://dx.doi.org/10.3390/photonics10020106.

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The filamentation of focused 300 fs laser pulses with variable polarization azimuth in bulk of synthetic HPHT diamond demonstrates the possibility of polarization-dependent bandgap control for crystal dielectric photoexcitation. This directly affects the value of the filamentation threshold power, which exhibits the distinct dependence on the polarization azimuth angle. The nonlinear photoluminescence yield, when focusing ultrashort laser pulses with variable polarization in bulk of the synthetic diamond, indicates different polarization-dependent regimes in the dynamics of electron-hole plasma formation, arising due to different processes of photoexcitation and recombination of free carriers during the filamentation process. Thus, at the onset of the filamentation process, at relatively low intensities, the photoluminescence yield rate depends on polarization azimuth controlling bandgap, while at high intensities the resulting dense absorbing plasma exhibits isotropy with respect to laser radiation polarization, and photoluminescence yield weakly depends on polarization azimuth.

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Bi, Xue Song, e Liang Zhu. "Joule Energy Deposition in Segmented Metal Wire Electrical Explosion". Advanced Materials Research 154-155 (ottobre 2010): 363–66. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.363.

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Electrical explosion of wire has a prosperous future in fine powder producing. In the process of electrical explosion of segmented metal wire (EESW),energy deposited in the wire was influenced by process variables such as the initial charging voltage of the capacitors, the length and the diameter of the segmented wire,and the electrode spacing. For understanding their relation completely, a series of experiments of electrical explosion was carried out with variations of the initial charging voltage and the segmented wire lengths and diameter. Results show that, energy deposition efficiency was weakly dependent on the wire length , whereas it has a strong dependence on the wire diameter, the initial charging voltage of the capacitors have an important influence on the energy deposition.

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Parent, L., e R. Coronado. "Reconstitution of the ATP-sensitive potassium channel of skeletal muscle. Activation by a G protein-dependent process." Journal of General Physiology 94, n. 3 (1 settembre 1989): 445–63. http://dx.doi.org/10.1085/jgp.94.3.445.

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Potassium channels inhibited by adenosine-5'-trisphosphate, K(ATP), found in the transverse tubular membrane of rabbit skeletal muscle were studied using the planar bilayer recording technique. In addition to the single-channel properties of K(ATP) we report its regulation of Mg2+ and by the guanosine-5'-trisphosphate analogue, GTP-y(gamma)-S. The K(ATP) channel (a) has a conductance of 67 pS in 250 mM internal, 50 mM external KCl, and rectifies weakly at holding potentials more positive than 50 mV, (b) is not activated by internal Ca2+ or membrane depolarization, (c) has a permeability ratio PK/PNa greater than 50, and (d) is inhibited by millimolar internal ATP. Activity of K(ATP), measured as open channel probability as a function of time, was unstable at all holding potentials and decreases continuously within a few minutes after a recording is initiated. After a decrease in activity, GTP-y-S (100 microM) added to the internal side reactivated K(ATP) channels but only transiently. In the presence of internal 1 mM Mg2+, GTP-y-S produced a sustained reactivation lasting 20-45 min. Incubation of purified t-tubule vesicles with AlF4 increased the activity of K(ATP) channels, mimicking the effect of GTP-y-S. The effect of AlF4 and the requirement of GTP-y-S plus Mg2+ for sustained channel activation suggests that a nucleotide-binding G protein regulates ATP-sensitive K channels in the t-tuble membrane of rabbit skeletal muscle.

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Wu, Yongbo, Linfeng Lan, Penghui He, Yilong Lin, Caihao Deng, Siting Chen e Junbiao Peng. "Influence of Hydrogen Ions on the Performance of Thin-Film Transistors with Solution-Processed AlOx Gate Dielectrics". Applied Sciences 11, n. 10 (12 maggio 2021): 4393. http://dx.doi.org/10.3390/app11104393.

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Over the past decade, there have been many reports on solution-processed oxide thin-film transistors (TFTs) with high mobility (even >100 cm2 V−1s−1). However, the capacitance uncertainty of the solution-processed oxide gate dielectrics leads to serious overestimation of the mobility. Here, solution-processed AlOx dielectrics are investigated systematically, and the effect of mobile ions on the frequency-dependent capacitance of the solution-processed AlOx dielectrics is also studied. It was found that the capacitance of the AlOx depends on the frequency seriously when the annealing temperature is lower than 300 °C, and the water treatment causes more seriously frequency-dependent capacitance. The strong frequency-dependent capacitance of the AlOx annealed at 250 or 300 °C is attributed to relaxation polarization of the weakly bound ions in the incompletely decomposed AlOx films. The water treatment introduces a large number of protons (H+) that would migrate to the ITO/AlOx interface under a certain electric field and form an electric double layer (EDL) that has ultrahigh capacitance at low frequency.

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Löpker, Andreas, e Wolfgang Stadje. "Hitting Times and the Running Maximum of Markovian Growth-Collapse Processes". Journal of Applied Probability 48, n. 02 (giugno 2011): 295–312. http://dx.doi.org/10.1017/s0021900200007889.

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We consider the level hitting times τy= inf{t≥ 0 |Xt=y} and the running maximum processMt= sup{Xs| 0 ≤s≤t} of a growth-collapse process (Xt)t≥0, defined as a [0, ∞)-valued Markov process that grows linearly between random ‘collapse’ times at which downward jumps with state-dependent distributions occur. We show how the moments and the Laplace transform of τycan be determined in terms of the extended generator ofXtand give a power series expansion of the reciprocal of Ee−sτy. We prove asymptotic results for τyandMt: for example, ifm(y) = Eτyis of rapid variation thenMt/m-1(t) →w1 ast→ ∞, wherem-1is the inverse function ofm, while ifm(y) is of regular variation with indexa∈ (0, ∞) andXtis ergodic, thenMt/m-1(t) converges weakly to a Fréchet distribution with exponenta. In several special cases we provide explicit formulae.

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Löpker, Andreas, e Wolfgang Stadje. "Hitting Times and the Running Maximum of Markovian Growth-Collapse Processes". Journal of Applied Probability 48, n. 2 (giugno 2011): 295–312. http://dx.doi.org/10.1239/jap/1308662628.

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Abstract (sommario):

We consider the level hitting times τy = inf{t ≥ 0 | Xt = y} and the running maximum process Mt = sup{Xs | 0 ≤ s ≤ t} of a growth-collapse process (Xt)t≥0, defined as a [0, ∞)-valued Markov process that grows linearly between random ‘collapse’ times at which downward jumps with state-dependent distributions occur. We show how the moments and the Laplace transform of τy can be determined in terms of the extended generator of Xt and give a power series expansion of the reciprocal of Ee−sτy. We prove asymptotic results for τy and Mt: for example, if m(y) = Eτy is of rapid variation then Mt / m-1(t) →w 1 as t → ∞, where m-1 is the inverse function of m, while if m(y) is of regular variation with index a ∈ (0, ∞) and Xt is ergodic, then Mt / m-1(t) converges weakly to a Fréchet distribution with exponent a. In several special cases we provide explicit formulae.

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Costantini, Antonella, Enrico Vaudano, Laura Pulcini, Lara Boatti, Elisa Gamalero e Emilia Garcia-Moruno. "Yeast Biodiversity in Vineyard during Grape Ripening: Comparison between Culture Dependent and NGS Analysis". Processes 10, n. 5 (3 maggio 2022): 901. http://dx.doi.org/10.3390/pr10050901.

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In this study, the evolution of the yeast microflora present on the berry surface, during the ripening of Barbera grapes, was monitored. Sampling was performed in three vineyards located in the “Nizza” Barbera d’Asti DOC zone and different methodologies have been employed. A culture-dependent method based on the identification of strains grown on solid media by ARDRA (Amplified Ribosomal DNA Restriction Analysis) and the D1-D2 domain of ribosomal 26S DNA capillary sequencing was coupled to NGS (Next Generation Sequencing) targeting ITS (Internal Transcribed Sequence) amplicons with the Illumina MiSeq platform. By using culture-dependent techniques, the most frequently detected species was the yeast-like fungus Aureobasidium pullulans, which was dominant in the culturable fraction. Among yeasts, the presence of oligotrophic basidiomycetes such as Cryptococcus spp., Rhodotorula graminis and Sporidiobolus pararoseus was observed at the beginning of ripening. Afterward, upon approaching the harvest, a succession of oxidative or weakly fermentative copiotrophic species occurs, such as Saturnispora diversa, Issatchenkia terricola, Hanseniaspora opuntiae, Starmerella bacillaris and Hanseniaspora uvarum. The massive sequencing revealed a larger number of species, respect to the culture-dependent data. Comparing the two different approaches used in this work, it is possible to highlight some similarities since Aureobasidium, Rhodotorula and Sporobolomyces were detected by both methods. On the contrary, genera Hanseniaspora, Issatchenkia and Saturnispora were revealed by culture-dependent methods, but not by NGS, while Saccharomyces spp. were identified, with low frequency, only by NGS. The integrated application of NGS sequencing and culture-dependent techniques provides a comprehensive view of mycodiversity in the wine-growing environment, especially for yeasts with low abundance.

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Li, Long, Shu-Qing Zhong e Zi-Gao Dai. "Photospheric Velocity Evolution of SN 2020bvc: Signature of r-process Nucleosynthesis from a Collapsar". Astrophysical Journal Letters 952, n. 2 (1 agosto 2023): L39. http://dx.doi.org/10.3847/2041-8213/ace82b.

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Abstract Whether binary neutron star mergers are the only astrophysical site of rapid neutron-capture process (r-process) nucleosynthesis remains unknown. Collapsars associated with long gamma-ray bursts (GRBs) and hypernovae are promising candidates. Simulations have shown that outflows from collapsar accretion disks can produce enough r-process materials to explain the abundances in the universe. However, there is no observational evidence to confirm this result at present. SN 2020bvc is a broad-lined Type Ic (Ic-BL) supernova (SN) possibly associated with a low-luminosity GRB. Based on semi-analytic SN emission models with and without r-process materials, we perform a fitting to the multiband light curves and photospheric velocities of SN 2020bvc. We find that in a r-process-enriched model the mixing of r-process materials slows down the photospheric recession and therefore matches the velocity evolution better. The fitting results show that r-process materials with mass of ≈0.36 M ⊙ and opacity of ≈4 cm2 g−1 is needed to mix with about half of the SN ejecta. Our fitting results are weakly dependent on the nebular emission. Future statistical analysis of a sample of Type Ic-BL SNe helps us understand the contribution of collapsars to the r-process abundance.

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Papangelo, Antonio. "On the Effect of a Rate-Dependent Work of Adhesion in the Detachment of a Dimpled Surface". Applied Sciences 11, n. 7 (31 marzo 2021): 3107. http://dx.doi.org/10.3390/app11073107.

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Patterned surfaces have proven to be a valuable design to enhance adhesion, increasing hysteresis and the detachment stress at pull-off. To obtain high adhesive performance, soft materials are commonly, used, which easily conform to the countersurface, such as soft polymers and elastomers. Such materials are viscoelastic; i.e., they show rate-dependent properties. Here, the detachment of two half spaces is studied, one being flat and the other having a dimple in the limit of short range adhesion and a power law rate-dependent work of adhesion, as observed by several authors. Literature results have suggested that the dimpled surface would show pressure-sensitive adhesion, showing two possible adhered states, one weak, in partial contact, and one strong when full contact is achieved. By accounting for a power law rate-dependent work of adhesion, the “weak state” may be much stronger than it was in the purely elastic case, and hence the interface may be much more tough to separate. We study the pull-off detachment stress of the dimpled surface, showing that it weakly depends on the preload, but it is strongly affected by the dimensionless unloading rate. Finally, possible implications of the presented results in the detachment of soft materials from rough substrates are discussed.

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Campos, M. "Electrical Transport Properties of Doped Poly (p-phenylene)". Polymers and Polymer Composites 11, n. 5 (luglio 2003): 407–14. http://dx.doi.org/10.1177/096739110301100506.

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An experimental study of the temperature dependent dc electrical conductivity of doped poly (p-phenylene) in the range of 50-300 K has been presented. The results have been analyzed in the framework of some hopping models. We have observed that hopping models are not consistent with the temperature dependence of the conductivity data over the entire temperature range of measurement. We find that the logarithmic conductivity is proportional to Tβ, where the exponent β is independent of temperature. It is shown that the most probable transport process in this material for the entire range of temperature is due to multiphonon-assisted hopping of the charge carriers that interact weakly with phonons. The parameters obtained from the fits of the experimental data to this model appear reasonable.

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Wawrzkiewicz, Monika, e Zbigniew Hubicki. "Remazol Black B removal from aqueous solutions and wastewater using weakly basic anion exchange resins". Open Chemistry 9, n. 5 (1 ottobre 2011): 867–76. http://dx.doi.org/10.2478/s11532-011-0072-0.

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AbstractIn this study, the use of the weakly basic anion exchange resins of phenol-formaldehyde (Amberlyst A 23), polyacrylate (Amberlite IRA 67) and polystyrene (Lewatit MonoPlus MP 62) matrices for removal of the reactive dye Remazol Black B (RBB) from aqueous solution and wastewater were investigated. RBB sorption on the anion exchangers was a time dependent process. Color reduction percentiles of 75.2, 33.9 and 25.1% in wastewater treatment were found after 216 h of phase contact time with Lewatit MonoPlus MP 62, Amberlyst A 23 and Amberlite IRA 67, respectively. Inorganic salts and anionic surfactant action influenced RBB uptake by the anion exchangers. The amounts of dye retained by the anion exchangers increased with a rise in temperature. The maximum sorption capacities calculated from the Langmuir model were 66.4, 282.1 and 796.1 mg g−1 for Amberlite IRA 67, Amberlyst A 23 and Lewatit MonoPlus MP 62, respectively. Regeneration of phenol-formaldehyde and polystyrene resins were possible using 1 M NaOH, 2 M KSCN, 1M KSCN in 40–60% methanol as well as 1 M NaOH in 60% methanol.

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40

Wurster, James, e Benjamin T. Lewis. "Non-ideal magnetohydrodynamics versus turbulence II: Which is the dominant process in stellar core formation?" Monthly Notices of the Royal Astronomical Society 495, n. 4 (28 maggio 2020): 3807–18. http://dx.doi.org/10.1093/mnras/staa1340.

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ABSTRACT Non-ideal magnetohydrodynamics (MHD) is the dominant process. We investigate the effect of magnetic fields (ideal and non-ideal) and turbulence (sub- and transsonic) on the formation of protostars by following the gravitational collapse of 1 M⊙ gas clouds through the first hydrostatic core to stellar densities. The clouds are imposed with both rotational and turbulent velocities, and are threaded with a magnetic field that is parallel/antiparallel or perpendicular to the rotation axis; we investigate two rotation rates and four Mach numbers. The initial radius and mass of the stellar core are only weakly dependent on the initial parameters. In the models that include ideal MHD, the magnetic field strength implanted in the protostar at birth is much higher than observed, independent of the initial level of turbulence; only non-ideal MHD can reduce this strength to near or below the observed levels. This suggests that not only is ideal MHD an incomplete picture of star formation, but that the magnetic fields in low mass stars are implanted later in life by a dynamo process. Non-ideal MHD suppresses magnetically launched stellar core outflows, but turbulence permits thermally launched outflows to form a few years after stellar core formation.

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Muraoka, Azusa, Sumire Ikeyama e Yuzuka Minamia. "(Invited) Influence of Vibronic Interaction of Charge Transfer Excitons in PTB7/BTA-Based Nonfullerene Organic Solar Cells". ECS Meeting Abstracts MA2024-01, n. 13 (9 agosto 2024): 1053. http://dx.doi.org/10.1149/ma2024-01131053mtgabs.

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For the design of rational D/A interfaces, it is important to elucidate the dynamic processes of excitons generated at the D/A stacking structure interface and the photoelectric conversion mechanism. We predict that the charge-transfer excitons initially formed are weakly bound electron-hole polaron pairs, which dissociate without relaxing to the charge-transfer state and diffuse as free electron polarons and hole polarons. We consider this to be a nonadiabatic process due to oscillatory interactions in the initial charge-transfer excitonic state. In this study, we use time-dependent DFT to investigate the electronic structure, electron-hole distance, electron coupling in charge transfer state generated by photoexcitaion and the Huang- Rhys factors of the D/A complex BTAx, PCTBT/BTAx and PDCBT/BTAx (x = 1, 3)) in the excited state and the exciton-phonon coupling and nonadiabatic process. Based on the above, we aim to elucidate the role of vibronic interactions in CT excitonic states and the control of JSC and electron-hole recombination.

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LI, BAOMING, e DANIEL Y. KWOK. "Multi-dimensional transient process for a pulse ablating capillary discharge: modeling and experiment". Journal of Plasma Physics 70, n. 4 (27 luglio 2004): 397–413. http://dx.doi.org/10.1017/s0022377803002575.

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In recent years, ablative plasma generated by capillary discharge attracted considerable attention because of its possible applications in electrothermal launchers, laser-driven particle accelerators, thin-film deposition and soft X-ray lasers, etc. An electrical discharge through a capillary insulator heats the capillary plasma that provides further evaporation of the capillary wall and electrode. The created plasma is confined by the capillary wall, electrode material and flow in a specified chamber through a hollow electrode. The mass flux leaving the capillary in axial motion is replenished by a radial inward flow of matter. Thus the radial component of the mass flux plays a principal role in the mass and energy balance. In this paper, we present a theoretical model for a time-dependent magneto-hydrodynamical simulation to calculate the dynamic evolution of plasma flow and transportation in two-dimensional configurations combined with turbulent effect. The thermodynamic and transport properties are characterized by a model that describes the plasma composition, equation of state, internal energy, viscosity and thermal and electrical conductivity for a partially ionized multi-component plasma in the weakly non-ideal region, similar to that which exists in the ablation-controlled arcs. Our model results show that some of the well-known experimental features of this kind of discharge are confirmed, particularly the radial mass and energy transportation.

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Wu, Zhiwei. "Text characteristics, perceived difficulty and task performance in sight translation". Interpreting. International Journal of Research and Practice in Interpreting 21, n. 2 (11 novembre 2019): 196–219. http://dx.doi.org/10.1075/intp.00027.wu.

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Abstract This paper reports on an exploratory study examining the relationship between text characteristics, perceived difficulty and task performance in sight translation (ST). Twenty-nine undergraduate interpreters were asked to sight-translate six texts with different properties. Correlation analysis shows that Sophisticated Word Type and Mean Length of a T-unit are, respectively, the lexical and the syntactic variables having the highest correlations with all the three dependent variables (i.e. perceived difficulty, accuracy and fluency in ST performance). Surprisingly, the discoursal variables are weakly or modestly correlated with the dependent variables. Thematic analysis of the students’ reflective essays points to two hypothesized causal links among the three Ps in ST: task properties may cause decoding difficulties and cognitive overload in the cognitive process, which in turn lead to inaccuracy and dysfluency in ST performance. The research findings lend empirical support to the “shallow-scan hypothesis” in previous research. Finally, this study proposes a three-tier conceptual framework to inform and guide future research to operationalize variables in ST empirical studies. The pedagogical implications of ST are also discussed.

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Righi, Giulia, Julius Plescher, Franz-Philipp Schmidt, R. Kramer Campen, Stefano Fabris, Axel Knop-Gericke, Robert Schlögl, Travis E. Jones, Detre Teschner e Simone Piccinin. "On the origin of multihole oxygen evolution in haematite photoanodes". Nature Catalysis 5, n. 10 (19 ottobre 2022): 888–99. http://dx.doi.org/10.1038/s41929-022-00845-9.

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AbstractThe oxygen evolution reaction (OER) plays a crucial role in (photo)electrochemical devices that use renewable energy to produce synthetic fuels. Recent measurements on semiconducting oxides have found a power law dependence of the OER rate on surface hole density, suggesting a multihole mechanism. In this study, using transient photocurrent measurements, density functional theory simulations and microkinetic modelling, we have uncovered the origin of this behaviour in haematite. We show here that the OER rate has a third-order dependence on the surface hole density. We propose a mechanism wherein the reaction proceeds by accumulating oxidizing equivalents through a sequence of one-electron oxidations of surface hydroxy groups. The key O–O bond formation step occurs by the dissociative chemisorption of a hydroxide ion involving three oxyl sites. At variance with the case of metallic oxides, the activation energy of this step is weakly dependent on the surface hole coverage, leading to the observed power law.

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Chen, T. Y., e C. Miller. "Nonequilibrium gating and voltage dependence of the ClC-0 Cl- channel." Journal of General Physiology 108, n. 4 (1 ottobre 1996): 237–50. http://dx.doi.org/10.1085/jgp.108.4.237.

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The gating of ClC-0, the voltage-dependent Cl- channel from Torpedo electric organ, is strongly influenced by Cl- ions in the external solution. Raising external Cl- over the range 1-600 mM favors the fast-gating open state and disfavors the slow-gating inactivated state. Analysis of purified single ClC-0 channels reconstituted into planar lipid bilayers was used to identify the role of Cl- ions in the channel's fast voltage-dependent gating process. External, but not internal, Cl- had a major effect on the channel's opening rate constant. The closing rate was more sensitive to internal Cl- than to external Cl-. Both opening and closing rates varied with voltage. A model was derived that postulates (a) that in the channel's closed state, Cl- is accessible to a site located at the outer end of the conduction pore, where it binds in a voltage-independent fashion, (b) that this closed conformation can open, whether liganded by Cl- or not, in a weakly voltage-dependent fashion, (c) that the Cl(-)-liganded closed channel undergoes a conformational change to a different closed state, such that concomitant with this change, Cl- ion moves inward, conferring voltage-dependence to this step, and (d) that this new Cl(-)-liganded closed state opens with a very high rate. According to this picture, Cl- movement within the pre-open channel is the major source of voltage dependence, and charge movement intrinsic to the channel protein contributes very little to voltage-dependent gating of ClC-0. Moreover, since the Cl- activation site is probably located in the ion conduction pathway, the fast gating of ClC-0 is necessarily coupled to ion conduction, a nonequilibrium process.

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Caner, Mehmet. "Weak Convergence to a Matrix Stochastic Integral with Stable Processes". Econometric Theory 13, n. 4 (febbraio 1997): 506–28. http://dx.doi.org/10.1017/s0266466600005983.

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Abstract (sommario):

This paper generalizes the univariate results of Chan and Tran (1989, Econometric Theory 5, 354–362) and Phillips (1990, Econometric Theory 6, 44–62) to multivariate time series. We develop the limit theory for the least-squares estimate of a VAR(l) for a random walk with independent and identically distributed errors and for I(1) processes with weakly dependent errors whose distributions are in the domain of attraction of a stable law. The limit laws are represented by functional of a stable process. A semiparametric correction is used in order to asymptotically eliminate the “bias” term in the limit law. These results are also an extension of the multivariate limit theory for square-integrable disturbances derived by Phillips and Durlauf (1986, Review of Economic Studies 53, 473–495). Potential applications include tests for multivariate unit roots and cointegration.

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Higgins, John M., e Steven R. Sloan. "Stochastic modeling of human RBC alloimmunization: evidence for a distinct population of immunologic responders". Blood 112, n. 6 (15 settembre 2008): 2546–53. http://dx.doi.org/10.1182/blood-2008-03-146415.

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Abstract Red blood cell (RBC) transfusion is unique as a common large-scale intravenous introduction of foreign tissue and provides a valuable opportunity to study human immunologic response to intravenous foreign antigen. Patients receiving RBC transfusions are at risk of forming alloantibodies against donor RBC antigens, and valid estimates of alloimmunization risk are clinically important, but little is known about the factors governing this risk or, more generally, about determinants of human response to intravenous antigen. Here, we mine large electronic patient databases enabling us to model RBC alloimmunization as a stochastic process. We identify a subgroup of transfusion recipients that has a dramatically increased risk of alloimmunization that appears to be genetically determined because it is independent of common disease states, patient age, or the number of alloantibodies already formed, and only weakly dependent on transfusion count.

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Магомедов, М. Н. "Изменение параметров образования вакансий и самодиффузии в кристалле с температурой и давлением". Физика твердого тела 64, n. 4 (2022): 485. http://dx.doi.org/10.21883/ftt.2022.04.52189.240.

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An analytical method for calculating the parameters of the electroneutral vacancies formation and self-diffusion of atoms in a single-component crystal is proposed. The method is based on the 4-parameters pairwise Mie–Lennard-Jones interatomic interaction potential. The method allows calculating all the activation processes parameters: Gibbs energy, enthalpy, entropy and volume for both the vacancy formation process and the self-diffusion process. The method is applicable at any pressure (P) and temperature (T). The temperature dependencies of the activation processes parameters for gold are calculated from T = 10 K to 1330 K along two isobars P = 0 and 24 GPa. It is shown that at low temperatures, due to quantum regularities, activation parameters strongly depend on temperature, and the entropy of activation processes in this region has a negative value. In the high temperature region, the probability of vacancy formation and the self-diffusion coefficient pass into classical Arrhenius dependencies with a weakly temperature-dependent enthalpy and with a positive value of the activation process entropy. Good agreements were obtained with the estimates of activation parameters for gold known from the literature. The values of activation parameters at T = 0 K were discussed.

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Sun, Liang, Dehao Hu, Ziyu Zhang e Xiaoyan Deng. "Oxidative Degradation of Methylene Blue via PDS-Based Advanced Oxidation Process Using Natural Pyrite". International Journal of Environmental Research and Public Health 16, n. 23 (28 novembre 2019): 4773. http://dx.doi.org/10.3390/ijerph16234773.

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H2O2- and PDS-based reactions are two typical advanced oxidation processes (AOPs). In this paper, a comparative study of H2O2/PDS-based AOPs employing natural pyrite as a catalyst to degrade methylene blue (MB) was reported. The adaptive pH range in pyrite/PDS extended from 3 to 11, in contrast to the narrow effective pH range of 3–7 in pyrite/H2O2. As a result of the iron leaching, a synergistic effect of both homogeneous and heterogeneous catalysis was observed in pyrite/PDS, whereas heterogeneous catalytic oxidation dominated pyrite/H2O2. Furthermore, the batch results showed that the MB removal by pyrite/PDS was highly dependent on chemical conditions (e.g., pH, pyrite and PDS concentration, temperature). Powerful SO4•− was generated by pyrite rapidly under acidic or weakly acidic conditions, while SO4•− and PDS were assumed by OH− under alkaline condition. The lower pyrite loading (from 0.1 to 0.5 g/L) was affected the removal efficiency obviously, while the scavenging of SO4•− did not seem to be remarkable with the excessive amounts of pyrite (>0.5 g/L). Excessive amounts of PDS (>2 mmol/L) might negatively affect the pyrite/PDS system. The reaction temperature that increased from 20 to 40 °C had a positive effect on the degradation of MB. SEM and XRD showed that the passivation of catalyst did not occur due to the strong acid-production ability of pyrite/PDS, inhibiting the formation of Fe-oxide covering the pyrite surface.

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Phillips, P. C. B. "Time Series Regression With a Unit Root and Infinite-Variance Errors". Econometric Theory 6, n. 1 (marzo 1990): 44–62. http://dx.doi.org/10.1017/s0266466600004904.

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Abstract (sommario):

In [4] Chan and Tran give the limit theory for the least-squares coefficient in a random walk with i.i.d. (identically and independently distributed) errors that are in the domain of attraction of a stable law. This paper discusses their results and provides generalizations to the case of I(1) processes with weakly dependent errors whose distributions are in the domain of attraction of a stable law. General unit root tests are also studied. It is shown that the semiparametric corrections suggested by the author in other work [22] for the finite-variance case continue to work when the errors have infinite variance. Surprisingly, no modifications to the formulas given in [22] are required. The limit laws are expressed in terms of ratios of quadratic functional of a stable process rather than Brownian motion. The correction terms that eliminate nuisance parameter dependencies are random in the limit and involve multiple stochastic integrals that may be written in terms of the quadratic variation of the limiting stable process. Some extensions of these results to models with drifts and time trends are also indicated.

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