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Yoshikawa, Masaya, Toshiya Asai, Mitsuru Shiozaki i Takeshi Fujino. "Selective Ring Oscillator PUF with Statistics Correction Technique and its Evaluation". Transactions of the Institute of Systems, Control and Information Engineers 25, nr 1 (2012): 1–9. http://dx.doi.org/10.5687/iscie.25.1.
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Reddy D, Mr Janardhan, Giribabu Sadineni, V. V. Tejaswini, D. DivyaSree Bhavani, N. Kaveri i V. Divya Archana. "Fraud Resistant Off-Line Card Micropayments Using FRoDO and PUF". International Journal of Innovative Research in Engineering and Management 10, nr 2 (kwiecień 2023): 103–7. http://dx.doi.org/10.55524/ijirem.2023.10.2.19.
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The internet payment system, which is a widespread cybercrime, is a major issue nowadays. Attackers concentrate on point of sale (POS) systems, the point at which a bank or merchant initially obtains customer information, with the goal of stealing confidential customer information. Effective computer systems with a card reader and specialised software are POS architectures. In this situation, the attacker might utilise malicious software (MS) to steal card statistics. If the customer and the supplier are consistently cut off from the network in, no online payment is practical. If the community fails, attacker's side will attempt to steal the password from the users throughout the price, therefore a safe online transaction price may not be achievable. Due to the PoS information breaches, we recommend an offline micro-fee solution that is secure and protects privacy for the persistent attackers in our paper. We use the FRoDO protocol to make the payment simple and secure from attackers. This protocol not only checks the client's coins but also confirms the client's identity by using identification details. This protocol increases flexibility and security and boosts the device's efficiency by infusing a comfortable micro-charge between the client and carrier.
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Avaroğlu, Erdinç. "The implementation of ring oscillator based PUF designs in Field Programmable Gate Arrays using of different challenge". Physica A: Statistical Mechanics and its Applications 546 (maj 2020): 124291. http://dx.doi.org/10.1016/j.physa.2020.124291.
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Yue, Yang, Jiaxin Yin, Jingyi Xie, Shufang Wu, Hui Ding, Lifeng Han, Songtao Bie i in. "Comparative Analysis of Volatile Compounds in the Flower Buds of Three Panax Species Using Fast Gas Chromatography Electronic Nose, Headspace-Gas Chromatography-Ion Mobility Spectrometry, and Headspace Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry Coupled with Multivariate Statistical Analysis". Molecules 29, nr 3 (26.01.2024): 602. http://dx.doi.org/10.3390/molecules29030602.
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The flower buds of three Panax species (PGF: P. ginseng; PQF: P. quinquefolius; PNF: P. notoginseng) widely consumed as health tea are easily confused in market circulation. We aimed to develop a green, fast, and easy analysis strategy to distinguish PGF, PQF, and PNF. In this work, fast gas chromatography electronic nose (fast GC e-nose), headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), and headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) were utilized to comprehensively analyze the volatile organic components (VOCs) of three flowers. Meanwhile, a principal component analysis (PCA) and heatmap were applied to distinguish the VOCs identified in PGF, PQF, and PNF. A random forest (RF) analysis was used to screen key factors affecting the discrimination. As a result, 39, 68, and 78 VOCs were identified in three flowers using fast GC e-nose, HS-GC-IMS, and HS-SPME-GC-MS. Nine VOCs were selected as potential chemical markers based on a model of RF for distinguishing these three species. Conclusively, a complete VOC analysis strategy was created to provide a methodological reference for the rapid, simple, and environmentally friendly detection and identification of food products (tea, oil, honey, etc.) and herbs with flavor characteristics and to provide a basis for further specification of their quality and base sources.
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Röhler, Laura, Pernilla Bohlin-Nizzetto, Pawel Rostkowski, Roland Kallenborn i Martin Schlabach. "Non-target and suspect characterisation of organic contaminants in ambient air – Part 1: Combining a novel sample clean-up method with comprehensive two-dimensional gas chromatography". Atmospheric Chemistry and Physics 21, nr 3 (9.02.2021): 1697–716. http://dx.doi.org/10.5194/acp-21-1697-2021.
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Abstract. Long-term monitoring of regulated organic chemicals, such as legacy persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs), in ambient air provides valuable information about the compounds' environmental fate as well as temporal and spatial trends. This is the foundation to evaluate the effectiveness of national and international regulations for priority pollutants. Extracts of high-volume air samples, collected on glass fibre filters (GFF for particle phase) and polyurethane foam plugs (PUF for gaseous phase), for targeted analyses of legacy POPs are commonly cleaned by treatment with concentrated sulfuric acid, resulting in extracts clean from most interfering compounds and matrices that are suitable for multi-quantitative trace analysis. Such standardised methods, however, severely restrict the number of analytes for quantification and are not applicable when targeting new and emerging compounds as some may be less stable under acid treatment. Recently developed suspect and non-target screening analytical strategies (SUS and NTS, respectively) are shown to be effective evaluation tools aimed at identifying a high number of compounds of emerging concern. These strategies, combining highly sophisticated analytical technology with extensive data interpretation and statistics, are already widely accepted in environmental sciences for investigations of various environmental matrices, but their application to air samples is still very limited. In order to apply SUS and NTS for the identification of organic contaminants in air samples, an adapted and more wide-scope sample clean-up method is needed compared to the traditional method, which uses concentrated sulfuric acid. Analysis of raw air sample extracts without clean-up would generate extensive contamination of the analytical system, especially with PUF matrix-based compounds, and thus highly interfered mass spectra and detection limits which are unacceptable high for trace analysis in air samples. In this study, a novel wide-scope sample clean-up method for high-volume air samples has been developed and applied to real high-volume air samples, which facilitates simultaneous target, suspect and non-target analyses. The scope and efficiency of the method were quantitatively evaluated with organic compounds covering a wide range of polarities (logP 2–11), including legacy POPs, brominated flame retardants (BFRs), chlorinated pesticides and currently used pesticides (CUPs). In addition, data reduction and selection strategies for SUS and NTS were developed for comprehensive two-dimensional gas chromatography separation with low-resolution time-of-flight mass spectrometric detection (GC × GC-LRMS) data and applied to real high-volume air samples. Combination of the newly developed clean-up procedure and data treatment strategy enabled the prioritisation of over 600 compounds of interest in the particle phase (on GFF) and over 850 compounds in the gas phase (on PUF) out of over 25 000 chemical features detected in the raw dataset. Of these, 50 individual compounds were identified and confirmed with reference standards, 80 compounds were identified with a probable structure, and 774 compounds were assigned to various compound classes. In the dataset available here, 11 hitherto unknown halogenated compounds were detected. These unknown compounds were not yet listed in the available mass spectral libraries.
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Anju, Dr Vineeta Basotia i Dr Ritikesh Kumar. "Analysis on Probability Mass Function and Probability Density Function". Irish Interdisciplinary Journal of Science & Research 08, nr 01 (2024): 08–12. http://dx.doi.org/10.46759/iijsr.2024.8102.
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Probability Mass Function (PMF) and Probability Density Function (PDF) are fundamental concepts in probability theory and statistics that play a crucial role in describing the probability distribution of random variables. This abstract provides a comprehensive overview of these concepts, highlighting their definitions, characteristics, and applications. The Probability Mass Function is a concept primarily associated with discrete random variables. It defines the probability of a specific outcome occurring. The PMF assigns probabilities to individual values in the sample space, providing a clear picture of the likelihood of each possible outcome. Commonly denoted as P(X=x), where X is the random variable and x is a specific value, the PMF must satisfy two essential properties: non-negativity and the sum of probabilities over all possible outcomes equals one. On the other hand, the Probability Density Function is a concept applied to continuous random variables. Unlike the PMF, which deals with specific values, the PDF deals with ranges of values. The PDF represents the probability that a continuous random variable falls within a given interval. Denoted as f(x), it is essential to note that the probability of any specific point is zero, and instead, probabilities are defined for intervals. The area under the PDF curve over a given interval corresponds to the probability of the random variable falling within that interval. Understanding the differences and similarities between PMF and PDF is crucial for statistical analysis. While PMF is discrete and deals with specific values, PDF is continuous and provides probabilities for intervals. Both functions are integral to the calculation of various statistical measures, including expected values, variance, and standard deviation. This abstract concludes with a discussion of practical applications in diverse fields, such as finance, engineering, and natural sciences, where a deep understanding of PMF and PDF is essential for making informed decisions and drawing meaningful conclusions from data. The integration of these concepts into statistical models and analyses enhances the accuracy and reliability of predictions, making PMF and PDF indispensable tools in the field of probability and statistics
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Pergolotti, Mackenzi, Jessica A. Lavery, Bryce B. Reeve i Stacie Dusetzina. "The financial burden of rehabilitation: Variation in clinician charges and implications for patient financial liability." Journal of Clinical Oncology 32, nr 30_suppl (20.10.2014): 40. http://dx.doi.org/10.1200/jco.2014.32.30_suppl.40.
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40 Background: Occupational and Physical therapies (OT/PT) are effective treatments to decrease disability and functional status. Few studies have examined the variations in the cost of outpatient OT/PT. For adults with cancer, the added financial burden of cancer rehabilitation is unknown. The study objectives were to (1) describe the variation in patient financial burden for the most commonly used OT/PT services by the provider type (either OT or PT) and State; and (2) determine the impact of therapy caps on the price of service provided among Medicare beneficiaries. Methods: This retrospective, population-based study used the Medicare Provider Utilization and Payment Data Public Use File (PUF), released in April 2014 by the Center for Medicare and Medicaid Services (CMS) to examine variations in care by level of insurance (uninsured, insured and reimbursed), between providers and across states with descriptive statistics. We also examined the impact of the therapy cap on number of visits allowed and the proposed reduction of the therapy cap dollar amount on services use and patient out-of-pocket liability. Results: 3,663 (9.2%) OT’s and 36,247 (90.8%) PT’s were included. Differences between provider’s charges were minimal. Wisconsin, Illinois, Tennessee and Texas had the most inflated charges, respectively, for OT and PT. 12-14 visits plus evaluation are covered under 2012 therapy cap, and the amount of visits would be cut to 7-9 with the MedPAC cap. Conclusions: This study suggests there is wide variation between the potential patient liability for the price of OT/PT based on service provided, state received and insurance coverage. For older adults with cancer who need OT/PT services, this will be an additional cost to their care. Patients without insurance pay a premium for OT/PT services.
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El Sayed, Ahmad, i Roydon A. Fraser. "Conditional Moment Closure Modelling of a Lifted H2/N2Turbulent Jet Flame Using the Presumed Mapping Function Approach". Journal of Combustion 2015 (2015): 1–24. http://dx.doi.org/10.1155/2015/257145.
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A lifted hydrogen/nitrogen turbulent jet flame issuing into a vitiated coflow is investigated using the conditional moment closure (CMC) supplemented by the presumed mapping function (PMF) approach for the modelling of conditional mixing and velocity statistics. Using a prescribed reference field, the PMF approach yields a presumed probability density function (PDF) for the mixture fraction, which is then used in closing the conditional scalar dissipation rate (CSDR) and conditional velocity in a fully consistent manner. These closures are applied to a lifted flame and the findings are compared to previous results obtained usingβ-PDF-based closures over a range of coflow temperatures (Tc). The PMF results are in line with those of theβ-PDF and compare well to measurements. The transport budgets in mixture fraction and physical spaces and the radical history ahead of the stabilisation height indicate that the stabilisation mechanism is susceptible toTc. As in the previousβ-PDF calculations, autoignition around the “most reactive” mixture fraction remains the controlling mechanism for sufficiently highTc. Departure from theβ-PDF predictions is observed whenTcis decreased as PMF predicts stabilisation by means of premixed flame propagation. This conclusion is based on the observation that lean mixtures are heated by downstream burning mixtures in a preheat zone developing ahead of the stabilization height. The spurious sources, which stem from inconsistent CSDR modelling, are further investigated. The findings reveal that their effect is small but nonnegligible, most notably within the flame zone.
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Tyopine, Hanmaikyur. "Online Marketing and Consumer Buying Behaviour of Electronic Products in the North Central Zone of Nigeria". Journal of Advance Research in Business Management and Accounting (ISSN: 2456-3544) 5, nr 5 (31.05.2019): 01–19. http://dx.doi.org/10.53555/nnbma.v5i5.749.
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This study examined effects of online marketing and consumer buying behaviour of electronic products in the north central zone of Nigeria. The population of this study comprised online marketers and online consumers in the seven states in north central zone of Nigeria. Because the population is infinite, a sample of 385 respondents were taken from marketers and the online consumers. Information was obtained from the respondents using a structured questionnaire. The data collected were analyzed using descriptive statistics such as frequency, simple percentage and the relationship between the variables of the model was tested using multiple linear regression analysis. The result of the regression analysis indicates that a negative relationship exist between perceived risk on consumer (PRK) and consumer buying behavior of electronic products in the north central zone of Nigeria (CBHV) and the relationship is not statistically significant (p>0.05). A positive relationship exist between perceived enjoyment (PEN) and consumer buying behavior of electronic products in the north central zone of Nigeria (CBHV) and the relationship is statistically significant (p<0.05). Perceived ease of use (PEU) was positively related to consumer buying behavior of electronic products in the north central zone of Nigeria (CBHV) and the relationship is statistically significant (p<0.05). Perceived usefulness (PUF) was negatively related to consumer buying behavior of electronic products in the north central zone of Nigeria (CBHV) and the relationship is not statistically significant (p>0.05). A positive relationship exist between perceived convenience (PCN) and consumer buying behavior of electronic products in the north central zone of Nigeria (CBHV) and the relationship is statistically significant (p<0.05). It was concluded that majority of the respondents whopatronize online shopping adopt that because of the convenience and time saving factor they obtain from it. It was recommended among others that owners of online marketing platform should ensure that they make their website dynamic and user friendly so as to attract customerswho will derive comfort and satisfaction transacting from the comfort of their homes.
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KÖROĞLU, Ozan, i Feza ARIKAN. "Regional ionospheric trend statistics: IONOLAB-PDF". TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES 25 (2017): 1773–83. http://dx.doi.org/10.3906/elk-1602-265.
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Buyanovsky, A. I. "USE OF FISHERIES STATISTICS FOR THE TANNER CRAB STOCK DYNAMICS". Problems of fisheries 20, nr 4 (2019): 497–512. http://dx.doi.org/10.36038/0234-2774-2019-20-4-497-512.
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Raghuveer, M. R. "Third-order statistics: issue of PDF symmetry". IEEE Transactions on Signal Processing 43, nr 7 (lipiec 1995): 1736–38. http://dx.doi.org/10.1109/78.398740.
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Gough, Alex, i Cora Uhlemann. "One-Point Statistics Matter in Extended Cosmologies". Universe 8, nr 1 (17.01.2022): 55. http://dx.doi.org/10.3390/universe8010055.
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The late universe contains a wealth of information about fundamental physics and gravity, wrapped up in non-Gaussian fields. To make use of as much information as possible, it is necessary to go beyond two-point statistics. Rather than going to higher-order N-point correlation functions, we demonstrate that the probability distribution function (PDF) of spheres in the matter field (a one-point function) already contains a significant amount of this non-Gaussian information. The matter PDF dissects different density environments which are lumped together in two-point statistics, making it particularly useful for probing modifications of gravity or expansion history. Our approach in Cataneo et al. 2021 extends the success of Large Deviation Theory for predicting the matter PDF in ΛCDM in these “extended” cosmologies. A Fisher forecast demonstrates the information content in the matter PDF via constraints for a Euclid-like survey volume combining the 3D matter PDF with the 3D matter power spectrum. Adding the matter PDF halves the uncertainties on parameters in an evolving dark energy model, relative to the power spectrum alone. Additionally, the matter PDF contains enough non-linear information to substantially increase the detection significance of departures from General Relativity, with improvements up to six times the power spectrum alone. This analysis demonstrates that the matter PDF is a promising non-Gaussian statistic for extracting cosmological information, particularly for beyond ΛCDM models.
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Nelson, Ariel Ann, Aniko Szabo i Deepak Kilari. "Impact of cytoreductive nephrectomy (CRN) on overall survival (OS) in metastatic non–clear cell renal cancer (nccRCC)." Journal of Clinical Oncology 41, nr 6_suppl (20.02.2023): 730. http://dx.doi.org/10.1200/jco.2023.41.6_suppl.730.
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730 Background: Non-clear cell renal cell carcinoma (nccRCC) accounts for 25% of kidney cancer diagnoses and encompasses a diverse group of kidney tumors with distinct biology for which treatment in the metastatic setting is evolving. The role of CRN for nccRCC population in the current treatment landscape remains unclear. Methods: We retrospectively identified patients (pts) with nccRCC from The National Cancer Database (NCDB) participant user file (PUF) for Kidney and Renal Pelvis Tumors. Pts with de novo metastatic disease diagnosed between 2006 and 2017, received systemic treatment (trt) with immunotherapy (IO) or non-immunotherapy (NIO) and either underwent or could have undergone a CRN were selected. Demographic and disease characteristics were summarized using descriptive statistics. The cumulative incidence of CRN with death without CRN as a competing risk, was estimated using the Nelson-Aalen estimator. The association of each demographic and disease characteristic on the cumulative incidence of CRN was evaluated using univariate Fine-Gray regression. The effect of CRN on survival was visualized using a Simon-Makuch plot. P values were based on Mantel-Byar test. Cox regression with a time-dependent predictor was used to estimate the change in the hazard of death after CRN. Results: We identified 3644 pts, 72% male, mean age 61 ±13 years. Nearly 40% of pts (n=1453) had sarcomatoid histology, followed by 30% with papillary (n=1075). Most pts, 96% (n=3489) received NIO systemic trt and only 9% were treated with IO (n=319). Nearly half of the study population (45%) underwent CRN (n=1642). Of these, 95% received NIO trt (n=1564) and 9% received IO (n=152). Pts who underwent CRN were younger and less likely to have bone, brain or liver metastases. Minority pts were less likely to undergo CRN. Mean time from dx to surgery was 1.1 ±1.7 months. For all pts, mOS was 9 months (95% CI: 8.6-9.4). OS was improved for pts who underwent CRN vs those who did not (11.3 vs 7.5 months, p<0.0001). In multivariate analysis, cytoreductive nephrectomy was associated with a reduction in the risk of death, HR 0.73 (95% CI: 0.68, 0.80, p<.0001). Conclusions: For pts with de novo metastatic nccRCC, CRN is associated with improved outcomes. Further analysis regarding the effect of treatment regimens on survival outcomes is warranted and planned. Prospective randomized trials in the modern treatment era are needed to further assess the timing and impact of CRN on outcomes in pts with metastatic nccRCC. [Table: see text]
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Kumar, Sumit, M. J. S. Khan i Surinder Kumar. "Concomitant of Order Statistics from New Bivariate Gompertz Distribution". Journal of Modern Applied Statistical Methods 18, nr 2 (17.09.2020): 2–20. http://dx.doi.org/10.22237/jmasm/1604189820.
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For the new bivariate Gompertz distribution, the expression for probability density function (pdf) of rth order statistics and pdf of concomitant arising from rth order statistics are derived. The properties of concomitant arising from the corresponding order statistics are used to derive these results. The exact expression for moment generating function (mgf) of concomitant of order rth statistics is derived. Also, the mean of concomitant arising from rth order statistics is computed using the mgf of concomitant of rth order statistics, and the exact expression for joint density of concomitant of two non-adjacent order statistics are derived.
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Haghish, E. F. "Rethinking Literate Programming in Statistics". Stata Journal: Promoting communications on statistics and Stata 16, nr 4 (grudzień 2016): 938–63. http://dx.doi.org/10.1177/1536867x1601600408.
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Literate programming is becoming increasingly trendy for data analysis because it allows the generation of dynamic-analysis reports for communicating data analysis and eliminates untraceable human errors in analysis reports. Traditionally, literate programming includes separate processes for compiling the code and preparing the documentation. While this workflow might be satisfactory for software documentation, it is not ideal for writing statistical analysis reports. Instead, these processes should run in parallel. In this article, I introduce the weaver package, which examines this idea by creating a new log system in HTML or LATEX that can be used simultaneously with the Stata log system. The new log system provides many features that the Stata log system lacks; for example, it can render mathematical notations, insert figures, create publication-ready dynamic tables, and style text, and it includes a built-in syntax highlighter. The weaver package also produces dynamic PDF documents by converting the HTML log to PDF or by typesetting the LATEX log and thus provides a real-time preview of the document without recompiling the code. I also discuss potential applications of the weaver package.
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Nuryani, Nuryani. "Support Vector Method with Radial Basis Function and Multi-Segment of Electrocardiogram for Paroxysmal Atrial Fibrillation Recognition". INDONESIAN JOURNAL OF APPLIED PHYSICS 10, nr 2 (31.10.2020): 148. http://dx.doi.org/10.13057/ijap.v10i2.46263.
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Paroxysmal Atrial fibrillation (PAF) is a heart problem relating to irregular and rapid beating of the heart atria. It has risk of stroke and is independently associated with risk of mortality. Early information of PAF episode is important for a patient to have appropriate treatment to reduce atrial fibrillation complications. This article presents a new strategy to detect PAF with base of statistical electrocardiographic features and a support vector machine (SVM). R-peak series of electrocardiogram were segmented and were extracted to find the statistics of RR intervals. Different approaches in relation with the segmentation were investigated. Two-class SVM with radial basis function (RBF) and the statistics of RR intervals were examined for PAF detection. Using clinical data of patients with PAF, the proposed strategy showed excellent performance of 99.17% in terms of accuracy. The experimental result indicated that the appropriate statistics of RR intervals and SVM-RBF with its suitable parameters can perform well for PAF detection.
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Begum, Anjuman A., i A. H. Khan. "Concomitants of Order Statistics from Gumbel's Bivariate Weibull Distribution". Calcutta Statistical Association Bulletin 47, nr 3-4 (wrzesień 1997): 133–40. http://dx.doi.org/10.1177/0008068319970301.
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The probability density function (pdf) of the rth, 1 ≤ r ≤ n and joint pdf of the rth and sth, 1 ≤ r < s ≤ n, concomitants of ordered statistics are derived for Gumbel's bivariate Weibull distribution and their single moments are obtained. Also their means and variances are tabulated.
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Liu, Jian, Yuhang Hu i Jing-Dong Bao. "The Lévy walk with rests under stochastic resetting". Journal of Statistical Mechanics: Theory and Experiment 2023, nr 7 (1.07.2023): 073202. http://dx.doi.org/10.1088/1742-5468/ace3b1.
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Abstract The Lévy walk with rests (LWR) model is a typical two-state stochastic process that has been widely and successfully adopted in the study of intermittent stochastic phenomena in physical and biological systems. Stochastic processes under resetting provide treatable and interesting schemes to study foraging and search strategies. In this manuscript, we focus on the anomalous diffusive behavior of the LWR under stochastic resetting. We consider both the case of instantaneous resetting, in which the particle stochastically returns to a given position immediately, and the case of noninstantaneous resetting, in which the particle returns to a given position with a finite velocity. The anomalous diffusive behaviors are analyzed and discussed by calculating the mean squared displacement analytically and numerically. Results reveal that the stochastic resetting can not only hinder the diffusion, where the diffusion evolves toward a saturation state, but also enhances it, where as compared with the LWR without resetting, the diffusion exponent surprisingly increases. As far as we know, the enhancement effect caused by stochastic resetting has not yet been reported. In addition, the resetting time probability density function (PDF) of the instantaneous resetting and the return time PDF of the noninstantaneous resetting are studied. Results reveal that the resetting time PDF could follow a power law provided that the sojourn time PDF is power-law distributed and the sojourn time with a heavier tail plays a decisive role in determining the resetting time PDF, whereas the shape of the return time PDF is determined by not only by the sojourn time PDF, but also by the return manner.
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Kou, Lei, Wuxue Li i Jujie Wu. "Permeability Prediction of Saturated Geomaterials with Revised Pore–Solid Fractal Model and Critical Path Analysis". Fractal and Fractional 6, nr 7 (23.06.2022): 351. http://dx.doi.org/10.3390/fractalfract6070351.
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The revised pore–solid fractal (PSF) model is presented by using the largest inscribed circle-based geometries of squares or cubes to replace the original pore or solid subregions as the new pore or solid phase in porous media. The revised PSF model changes the discrete lacunar pore and solid phases in the original PSF model to integrated. Permeability is an intrinsic property of geomaterials and has broad applications in exploring fluid flow and species transport. Based on the revised PSF model and critical path analysis, a fractal model for predicting the permeability of saturated geomaterials is proposed. The permeability prediction model is verified by comparison with the existing predicted model and the laboratory testing. The results show that the predicted permeabilities match the measured values very well. This work provides a theoretical framework for the revised PSF model and its application in predicting the permeability of geomaterials.
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Pauliukevičienė, Gintarė, i Jelena Stankevičienė. "Assessing statistical link between FinTech PEST environment and achievement of SDGs". Public and Municipal Finance 10, nr 1 (15.07.2021): 47–66. http://dx.doi.org/10.21511/pmf.10(1).2021.05.
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Implementation of SDGs is the unified goal of 193 UN Member States. FinTech plays a crucial role in achieving it. Therefore, the development of FinTech must be facilitated through proper policy-making and public finance, creating beneficial PEST conditions. However, the interaction of the FinTech PEST environment and achievement of SDGs is a topic that has not yet been addressed. The purpose of this study is to assess the link between these two indicators using statistical methods, indicate SDGs having the strongest link to FinTech PEST environment, and explain the interface to facilitate its useful application within government and financial regulations, as well as administration of the state and municipal financial entities. The results show that the economic and investment potential of Northern Europe is caused by the most favorable PEST environment for FinTech sector development, and demonstrate the existence of a statistical link between FinTech PEST environment and SDG4, SDG8, SDG9, SDG16. There is a clear trend – the more favorable the FinTech PEST environment, the better the achievement of SDGs, the better results of Sustainable Finance indicators, and the higher the Sustainable Finance typology assigned to the country. These results suggest that the goals, targets, and indicators of SDG4, SDG8, SDG9, and SDG16 contribute to the formation of a favorable environment and are conductive to the sustainable development of the FinTech industry in a country. Therefore, sustainability in the development of FinTech industry and finance, and the achievement of SDGs, is a circular process of three interacting factors.
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Pavlović, Dragana Č., Nikola M. Sekulović, Gradimir V. Milovanović, Aleksandra S. Panajotović, Mihajlo Č. Stefanović i Zoran J. Popović. "Statistics for Ratios of Rayleigh, Rician, Nakagami-m, and Weibull Distributed Random Variables". Mathematical Problems in Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/252804.
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The distributions of ratios of random variables are of interest in many areas of the sciences. In this brief paper, we present the joint probability density function (PDF) and PDF of maximum of ratiosμ1=R1/r1andμ2=R2/r2for the cases whereR1,R2,r1, andr2are Rayleigh, Rician, Nakagami-m, and Weibull distributed random variables. Random variablesR1andR2, as well as random variablesr1andr2, are correlated. Ascertaining on the suitability of the Weibull distribution to describe fading in both indoor and outdoor environments, special attention is dedicated to the case of Weibull random variables. For this case, analytical expressions for the joint PDF, PDF of maximum, PDF of minimum, and product moments of arbitrary number of ratiosμi=Ri/ri,i=1,…,Lare obtained. Random variables in numerator,Ri, as well as random variables in denominator,ri, are exponentially correlated. To the best of the authors' knowledge, analytical expressions for the PDF of minimum and product moments of{μi}i=1Lare novel in the open technical literature. The proposed mathematical analysis is complemented by various numerical results. An application of presented theoretical results is illustrated with respect to performance assessment of wireless systems.
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Házi, Gábor, i Gábor Tóth. "Regional statistics in confined two-dimensional decaying turbulence". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, nr 1945 (28.06.2011): 2555–64. http://dx.doi.org/10.1098/rsta.2011.0070.
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Two-dimensional decaying turbulence in a square container has been simulated using the lattice Boltzmann method. The probability density function (PDF) of the vorticity and the particle distribution functions have been determined at various regions of the domain. It is shown that, after the initial stage of decay, the regional area averaged enstrophy fluctuates strongly around a mean value in time. The ratio of the regional mean and the overall enstrophies increases monotonously with increasing distance from the wall. This function shows a similar shape to the axial mean velocity profile of turbulent channel flows. The PDF of the vorticity peaks at zero and is nearly symmetric considering the statistics in the overall domain. Approaching the wall, the PDFs become skewed owing to the boundary layer.
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Thijssen, J. M., B. J. Oosterveld i R. L. Romijn. "Phase-Derivative Imaging III: Theoretical Derivation of First and Second Order Statistics". Ultrasonic Imaging 12, nr 1 (styczeń 1990): 17–34. http://dx.doi.org/10.1177/016173469001200102.
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The echo signal obtained from a homogenous and isotropically scattering medium can be described as a Poisson time series which is convolved with the transmission pulse of the transducer. The probability density function (pdf) of this signal approximates to a Gaussian pdf for a narrowband pulse waveform. Methods to derive the phase-derivative (PD) signal from the complex envelope and the preenvelope of the echo signal are described. The first order pdf of the PD asymptotically becomes a Gaussian pdf by smoothing. Since the rectified PD is employed to obtain 2-dimensional grey scale images, the first order pdf as well as the signal-to-noise ratio (SNR) of this signal are also derived. The rectified PD is further smoothed by a cosine time window prior to the imaging. The SNR and the autocorrelation function (in the axial direction) of this latter signal can be derived under the assumption of a Gaussian spectrum of the transmission pulse. These first and second order characteristics of the PD images are calculated for the conditions employed in simulations and experiments reported previously and are quantitatively compared to the values obtained from these.
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Palacios, Juan C., Sofiane Bourouaine i Jean C. Perez. "On the Statistics of Elsasser Increments in Solar Wind and Magnetohydrodynamic Turbulence". Astrophysical Journal Letters 940, nr 1 (1.11.2022): L20. http://dx.doi.org/10.3847/2041-8213/ac92f6.
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Abstract In this Letter we investigate the dependency with scale of the empirical probability distribution functions (PDF) of Elsasser increments using large sets of WIND data (collected between 1995 and 2017) near 1 au. The empirical PDF are compared to the ones obtained from high-resolution numerical simulations of steadily driven, homogeneous reduced MHD turbulence on a 20483 rectangular mesh. A large statistical sample of Alfvénic increments is obtained by using conditional analysis based on the solar wind average properties. The PDF tails obtained from observations and numerical simulations are found to have exponential behavior in the inertial range, with an exponential decrement that satisfies power laws of the form α l ∝ l −μ , where l is the scale size, with μ between 0.17 and 0.25 for observations and 0.43 for simulations. PDF tails were extrapolated assuming their exponential behavior extends to arbitrarily large increments in order to determine structure function scaling laws at very high orders. Our results point to potentially universal scaling laws governing the PDF of Elsasser increments and to an alternative approach to investigate high-order statistics in solar wind observations.
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Haas, Charles N., i Barbara Heller. "Statistics of Microbial Disinfection". Water Science and Technology 21, nr 3 (1.03.1989): 197–201. http://dx.doi.org/10.2166/wst.1989.0099.
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Engineering adequate disinfection processes and assessing risks associated with various disinfection options requires knowledge of kinetics of microbial inactivation as a function of design variables (e.g., dose, contact time). Often such information is obtained in batch studies and extrapolated to design conditions. By Monte Carlo techniques, we have shown that the use of a direct maximum likelihood evaluation for two types of data normally encountered, counts (PFU or CFU) and dilution experiments (MPN), leads to estimates of microbial inactivation rate parameters having lower bias and variance than other data reduction normally employed. This paper reviews the methodology of this technique and provides the theory for the computation of confidence limits for parameter estimates, and discusses how the data may be checked for consistency (goodness of fit determination).
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Vidybida, Alexander. "Relation Between Firing Statistics of Spiking Neuron with Instantaneous Feedback and Without Feedback". Fluctuation and Noise Letters 14, nr 04 (9.11.2015): 1550034. http://dx.doi.org/10.1142/s0219477515500340.
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We consider a class of spiking neuron models, defined by a set of conditions which are typical for basic threshold-type models like leaky integrate-and-fire, or binding neuron model and also for some artificial neurons. A neuron is fed with a point renewal process. A relation between the three probability density functions (PDF): (i) PDF of input interspike intervals ISIs, (ii) PDF of output interspike intervals of a neuron with a feedback and (iii) PDF for that same neuron without feedback is derived. This allows to calculate any one of the three PDFs provided the remaining two are given. Similar relation between corresponding means and variances is derived. The relations are checked exactly for the binding neuron model stimulated with Poisson stream.
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Nelson, Ariel Ann, Aniko Szabo i Deepak Kilari. "Impact of cytoreductive nephrectomy (CN) and treatment (trt) sequence on overall survival (OS) in metastatic non-clear cell renal cell cancer (nccRCC)." Journal of Clinical Oncology 42, nr 16_suppl (1.06.2024): e16543-e16543. http://dx.doi.org/10.1200/jco.2024.42.16_suppl.e16543.
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e16543 Background: nccRCC accounts for 25% of kidney cancer diagnoses and encompasses a diverse group of kidney tumors with distinct biology for which trt in the metastatic setting is evolving. The role of CN for nccRCC population in the current trt landscape remains unclear. Methods: We retrospectively identified patients (pts) with nccRCC from The National Cancer Database (NCDB) participant user file (PUF) for Kidney and Renal Pelvis Tumors. Pts with de novo metastatic disease diagnosed between 2015 and 2020, received systemic trt with immunotherapy (IO) or non-immunotherapy (NIO) and underwent or could have undergone a CN were selected. Pts classified as having sarcomatoid histology were excluded. Demographic and disease characteristics were summarized using descriptive statistics. The cumulative incidence of CN was estimated using the Nelson-Aalen estimator. The association of demographic and disease characteristics on the cumulative incidence of CN was evaluated using univariate Fine-Gray regression. The effect of CN on survival was visualized via Simon-Makuch plot. P values were based on Mantel-Byar test. Cox regression with a time-dependent predictor was used to estimate the change in the hazard of death after CN. Results: We identified 982 pts, median age 60 (18 – 90) years, 61% male, 69% Caucasian and 28% African American. nccRCC histology included 66.5% papillary (n=653), 10.4% chromophobe (n=102), 9.9% medullary (n=97), 8.8% collecting duct (n=86), 4.4% unclassified (n= 43). 69% of pts received NIO (n= 676), 14% received IO + NIO (n= 134), 18% received IO only (n= 172). 40% had CN (n=390), the majority of CN (86%) occurred within 3 months of diagnosis. 89% had CN followed by systemic trt (n=348), 4.3% underwent initial systemic trt followed by CN (n=42). Median OS was 11 months for the entire group. For those who had CN, mOS was 13.9 vs 10 months for no CN (p=0.002). CN was associated with improved survival; HR 0.79 (95% CI 0.68,0.92; p=0.002). Median OS for pts who received systemic trt followed by CN was 32.6 vs 12.8 months for those who had CN followed by systemic trt vs 10 months for those who had no CN, (p=0.001). Upfront systemic trt followed by CN and CN followed by systemic trt were both associated with improved survival, HR 0.56 (95% CI 0.36, 0.87; p=0.009) and HR 0.83 (95% CI 0.69,0.99; p= 0.034) respectively. Choice of systemic trt was not associated with improved OS (p = 0.139). Unclassified and medullary histology were associated with worse OS, HR 1.60 (95% CI 1.09, 2.34; p=0.015) and HR 2.04 (95% CI 1.46,2.84; p=0.002) respectively. Conclusions: CN is associated with improved outcomes for pts with de novo metastatic nccRCC. Sequencing upfront systemic trt followed by CN may improve survival. Prospective randomized trials in the modern trt era are needed and ongoing (Ie. PROBE trial NCT04510597) to further assess the timing and sequencing of CN in pts with nccRCC.
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Berman, Edward M., Jacqueline E. McCleary, Anton M. Koekemoer, Maximilien Franco, Nicole E. Drakos, Daizhong Liu, James W. Nightingale i in. "Efficient Point-spread Function Modeling with ShOpt.jl: A Point-spread Function Benchmarking Study with JWST NIRCam Imaging". Astronomical Journal 168, nr 4 (24.09.2024): 174. http://dx.doi.org/10.3847/1538-3881/ad6a0f.
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Abstract With their high angular resolutions of 30–100 mas, large fields of view, and complex optical systems, imagers on next-generation optical/near-infrared space observatories, such as the Near-Infrared Camera (NIRCam) on the James Webb Space Telescope, present new opportunities for science and also new challenges for empirical point-spread function (PSF) characterization. In this context, we introduce ShOpt, a new PSF fitting tool developed in Julia and designed to bridge the advanced features of PSFs in the full field of view (PIFF) with the computational efficiency of PSF Extractor (PSFEx). Along with ShOpt, we propose a suite of nonparametric statistics suitable for evaluating PSF fit quality in space-based imaging. Our study benchmarks ShOpt against the established PSF fitters PSFEx and PIFF using real and simulated COSMOS-Web Survey imaging. We assess their respective PSF model fidelity with our proposed diagnostic statistics and investigate their computational efficiencies, focusing on their processing speed relative to the complexity and size of the PSF models. We find that ShOpt can already achieve PSF model fidelity comparable to PSFEx and PIFF while maintaining competitive processing speeds, constructing PSF models for large NIRCam mosaics within minutes.
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Qian, J. "Non-Gaussian Statistics in Turbulence". International Journal of Modern Physics B 17, nr 22n24 (30.09.2003): 4316–20. http://dx.doi.org/10.1142/s0217979203022374.
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It is believed that non-Gaussian statistics of intermittency leads to anomalous scaling in turbulence, and self-similarity normal scaling corresponds to Gaussian assumptions. By a reasonable model of probability density function (PDF) of intermittent velocity increment, we demonstrate the possibility that non-Gaussian statistics may lead to self-similarity and normal scaling. The experimental facts of scaling-range exponents being anomalous, are not against a non-Gaussian self-similarity in the inertial range. In scaling ranges at experimental Reynolds numbers, viscous and large-scale effects are not negligible, the non-Gaussian self-similarity is broken due to viscous and large-scale effects, and anomalous scaling is observed.
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Uhlemann, Cora, Oliver Friedrich, Francisco Villaescusa-Navarro, Arka Banerjee i Sandrine Codis. "Fisher for complements: extracting cosmology and neutrino mass from the counts-in-cells PDF". Monthly Notices of the Royal Astronomical Society 495, nr 4 (4.05.2020): 4006–27. http://dx.doi.org/10.1093/mnras/staa1155.
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ABSTRACT We comprehensively analyse the cosmology dependence of counts-in-cells statistics. We focus on the shape of the one-point probability distribution function (PDF) of the matter density field at mildly non-linear scales. Based on large-deviation statistics, we parametrize the cosmology dependence of the matter PDF in terms of the linear power spectrum, the growth factor, the spherical collapse dynamics, and the non-linear variance. We extend our formalism to include massive neutrinos, finding that the total matter PDF is highly sensitive to the total neutrino mass Mν and can disentangle it from the clustering amplitude σ8. Using more than a million PDFs extracted from the Quijote simulations, we determine the response of the matter PDF to changing parameters in the νΛCDM model and successfully cross-validate the theoretical model and the simulation measurements. We present the first νΛCDM Fisher forecast for the matter PDF at multiple scales and redshifts, and its combination with the matter power spectrum. We establish that the matter PDF and the matter power spectrum are highly complementary at mildly non-linear scales. The matter PDF is particularly powerful for constraining the matter density Ωm, clustering amplitude σ8 and the total neutrino mass Mν. Adding the mildly non-linear matter PDF to the mildly non-linear matter power spectrum improves constraints on Ωm by a factor of 5 and σ8 by a factor of 2 when considering the three lowest redshifts. In our joint analysis of the matter PDF and matter power spectrum at three redshifts, the total neutrino mass is constrained to better than 0.01 eV with a total volume of 6 (Gpc h−1)3. We discuss how density-split statistics can be used to translate those encouraging results for the matter PDF into realistic observables in galaxy surveys.
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Weber, Nathan. "Misusing charitable statistics in evaluating fundraising performance". New Directions for Philanthropic Fundraising 1994, nr 3 (1994): 115–28. http://dx.doi.org/10.1002/pf.41219940308.
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El Sayed, Mohamed A., Mohamed A. El-Shorbagy, Farahat A. Farahat, Aisha F. Fareed i Mohamed A. Elsisy. "Stability of Parametric Intuitionistic Fuzzy Multi-Objective Fractional Transportation Problem". Fractal and Fractional 5, nr 4 (19.11.2021): 233. http://dx.doi.org/10.3390/fractalfract5040233.
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In this study, a parametric intuitionistic fuzzy multi-objective fractional transportation problem (PIF-MOFTP) is proposed. The current PIF-MOFTP has a single-scalar parameter in the objective functions and an intuitionistic fuzzy supply and demand. Based on the (α,β)-cut concept a parametric (α,β)-MOFTP is established. Then, a fuzzy goal programming (FGP) approach is utilized to obtain (α,β)-Pareto optimal solution. We investigated the stability set of the first kind (SSFK) corresponding to the solution by extending the Kuhn-Tucker optimality conditions of multi-objective programming problems. An algorithm to crystalize the progressing SSFK for PIF-MOFTP as well as an illustrative numerical example is presented.
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Suciu, N., L. Schüler, S. Attinger, C. Vamoș i P. Knabner. "Consistency issues in PDF methods". Analele Universitatii "Ovidius" Constanta - Seria Matematica 23, nr 3 (1.11.2015): 187–208. http://dx.doi.org/10.1515/auom-2015-0055.
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Abstract Concentrations of chemical species transported in random environments need to be statistically characterized by probability density functions (PDF). Solutions to evolution equations for the one-point one-time PDF are usually based on systems of computational particles described by Itô equations. We establish consistency conditions relating the concentration statistics to that of the Itô process and the solution of its associated Fokker-Planck equation to that of the PDF equation. In this frame, we use a recently proposed numerical method which approximates PDFs by particle densities obtained with a global random walk (GRW) algorithm. The GRW-PDF approach is illustrated for a problem of contaminant transport in groundwater.
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Firl, Grant J., i David A. Randall. "Fitting and Analyzing LES Using Multiple Trivariate Gaussians". Journal of the Atmospheric Sciences 72, nr 3 (24.02.2015): 1094–116. http://dx.doi.org/10.1175/jas-d-14-0192.1.
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Abstract Assumed-PDF methods for the parameterization of subgrid-scale processes in atmospheric models provide many benefits. Many currently used assumed-PDF schemes reconcile the high number of required PDF parameters with the relative paucity of input moments by employing simplifying assumptions that are difficult to test. This paper explores the possibility of constructing a trivariate double-Gaussian PDF from the first three orders of moments without simplifying assumptions and proves that no unique solution exists. In an effort to provide a path for future improvement of current assumed-PDF schemes, the expectation maximization (EM) algorithm for Gaussian mixture models is used with LES output of shallow cumulus, stratocumulus, and deep convection cases to determine “best fit” PDFs using from one through four Gaussian clusters. The EM PDFs are evaluated using PDF-diagnosed higher-order moments, PDF-diagnosed cloud statistics, and the Akaike information criterion. It was found that two Gaussian clusters were almost always adequate to represent both higher-order moments and cloud statistics like cloud fraction, water content, and vertical fluxes of cloud water and buoyancy in layered clouds such as stratocumulus and deep convective anvils. However, higher-order moments and higher-order cloud statistics were only properly represented when three or four Gaussians were used in the upper regions of shallow cumulus layers and throughout the active portion of deep convection. Evidence is also provided that several common assumptions employed to diagnose trivariate double-Gaussian PDFs from a minimum number of input moments are weak.
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Mohamad, Mustafa A., i Themistoklis P. Sapsis. "Sequential sampling strategy for extreme event statistics in nonlinear dynamical systems". Proceedings of the National Academy of Sciences 115, nr 44 (16.10.2018): 11138–43. http://dx.doi.org/10.1073/pnas.1813263115.
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We develop a method for the evaluation of extreme event statistics associated with nonlinear dynamical systems from a small number of samples. From an initial dataset of design points, we formulate a sequential strategy that provides the “next-best” data point (set of parameters) that when evaluated results in improved estimates of the probability density function (pdf) for a scalar quantity of interest. The approach uses Gaussian process regression to perform Bayesian inference on the parameter-to-observation map describing the quantity of interest. We then approximate the desired pdf along with uncertainty bounds using the posterior distribution of the inferred map. The next-best design point is sequentially determined through an optimization procedure that selects the point in parameter space that maximally reduces uncertainty between the estimated bounds of the pdf prediction. Since the optimization process uses only information from the inferred map, it has minimal computational cost. Moreover, the special form of the metric emphasizes the tails of the pdf. The method is practical for systems where the dimensionality of the parameter space is of moderate size and for problems where each sample is very expensive to obtain. We apply the method to estimate the extreme event statistics for a very high-dimensional system with millions of degrees of freedom: an offshore platform subjected to 3D irregular waves. It is demonstrated that the developed approach can accurately determine the extreme event statistics using a limited number of samples.
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Xue, Feng, Jiaqi Liu, Zhifeng Li, Shengdong Liu, Gang Meng i Li Zhang. "Mallows’ statistics C L : A novel criterion for parametric PSF estimation". Journal of Visual Communication and Image Representation 33 (listopad 2015): 115–22. http://dx.doi.org/10.1016/j.jvcir.2015.09.001.
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Fitch, A. C. "An Improved Double-Gaussian Closure for the Subgrid Vertical Velocity Probability Distribution Function". Journal of the Atmospheric Sciences 76, nr 1 (1.01.2019): 285–304. http://dx.doi.org/10.1175/jas-d-18-0149.1.
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Abstract The vertical velocity probability distribution function (PDF) is analyzed throughout the depth of the lower atmosphere, including the subcloud and cloud layers, in four large-eddy simulation (LES) cases of shallow cumulus and stratocumulus. Double-Gaussian PDF closures are examined to test their ability to represent a wide range of turbulence statistics, from stratocumulus cloud layers characterized by Gaussian turbulence to shallow cumulus cloud layers displaying strongly non-Gaussian turbulence statistics. While the majority of the model closures are found to perform well in the former case, the latter presents a considerable challenge. A new model closure is suggested that accounts for high skewness and kurtosis seen in shallow cumulus cloud layers. The well-established parabolic relationship between skewness and kurtosis is examined, with results in agreement with previous studies for the subcloud layer. In cumulus cloud layers, however, a modified relationship is necessary to improve performance. The new closure significantly improves the estimation of the vertical velocity PDF for shallow cumulus cloud layers, in addition to performing well for stratocumulus. In particular, the long updraft tail representing the bulk of cloudy points is much better represented and higher-order moments diagnosed from the PDF are also greatly improved. However, some deficiencies remain owing to fundamental limitations of representing highly non-Gaussian turbulence statistics with a double-Gaussian PDF.
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BUONFIGLI, Julio, Cristian QUINTERO, Diego SÁNCHEZ, Natalia LEIVA i Maria Teresa DAMIANI. "STATISTICAL VALIDATION OF TRIPLE COLOCALIZATION ANALYSIS". SOUTHERN JOURNAL OF SCIENCES 31, nr 36 (30.12.2023): 45–62. http://dx.doi.org/10.48141/sjs.v31.n36.2023_buonfigli_pgs_45_62.pdf.
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Background: in the last decades, colocalization analysis of fluorescently tagged biomolecules has proven to be a powerful approach to studying functional relationships between these biomolecules. However, in many cases, to give this analysis a biological meaning, colocalization coefficients must be tested statistically, comparing them with the colocalization expected by chance. Aim: It addressed the statistical significance of triple colocalization to distinguish real triple colocalization and classify different triple signal scenarios. Methods: we use biological and generated images of triple signal scenarios to contrast seven independent statistical facts with independent statistical tests. Three of these tests correspond to pairwise relationships (double scrambling tests), and the others correspond to triple relationships: single scrambling tests (red, green, and blue scrambling) and the triple scrambling test. The analysis and methodology proposed can be reproduced using the application developed in our laboratory. Results: In the study approach, we found true triple relationships ignored by using traditional methods of computing the statistical significance, while we could reinterpret cases of not significant triple colocalization wrongly considered as significant by traditional methods. Discussion: single scrambling tests can reveal significant triple colocalization for low levels of triple co-occurrence, even when all pairwise relationships were exclusion relationships. Moreover, on the other hand, single scrambling tests can reveal the absence of a significant triple colocalization for high levels of triple co-occurrence, even when all pairwise relationships were significant colocalization. Conclusion: all scrambling tests are useful to classify a specific scenario of a triple relationship. Dynamics like mitosis can be distinguished into their phases by triple signal relationships using these 7 independent statistical tests.
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Koehler, Steven A., Harold B. Weiss, Abdulrezzak Shakir, Stacey Shaeffer, Shaun Ladham, Leon Rozin, Joseph Dominick, Bruce A. Lawrence, Ted R. Miller i Cyril H. Wecht. "Accurately Assessing Elderly Fall Deaths Using Hospital Discharge and Vital Statistics Data". American Journal of Forensic Medicine and Pathology 27, nr 1 (marzec 2006): 30–35. http://dx.doi.org/10.1097/01.paf.0000202710.06605.20.
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Mortarini, L., i E. Ferrero. "A Lagrangian Stochastic Model for the concentration fluctuations". Atmospheric Chemistry and Physics Discussions 5, nr 3 (2.06.2005): 3621–39. http://dx.doi.org/10.5194/acpd-5-3621-2005.
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Abstract. A Lagrangian Stochastic Model for the two-particles dispersion, aiming at simulating the pollutant concentration fluctuations, is presented. Three model versions (1-D, 2-D and 3-D) are tested. Firstly the ability of the model to reproduce the two-particle statistics in a homogeneous isotropic turbulence is discussed, comparing the model results with theoretical predictions in terms of the probability density function (PDF) of the particles separation and its statistics. Then, the mean concentration and its fluctuations are considered and the results presented. The influence of the PDF of the particle separation on the concentration fluctuations is shown and discussed. We found that the separation PDF in the inertial subrange is not gaussian and this fact influences the predicted concentration fluctuations.
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Mortarini, L., i E. Ferrero. "A Lagrangian Stochastic Model for the concentration fluctuations". Atmospheric Chemistry and Physics 5, nr 9 (23.09.2005): 2539–45. http://dx.doi.org/10.5194/acp-5-2539-2005.
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Abstract. A Lagrangian Stochastic Model for the two-particles dispersion, aiming at simulating the pollutant concentration fluctuations, is presented. Three model versions (1-D, 2-D and 3-D) are tested. Firstly the ability of the model to reproduce the two-particle statistics in a homogeneous isotropic turbulence is discussed, comparing the model results with theoretical predictions in terms of the probability density function (PDF) of the particles separation and its statistics. Then, the mean concentration and its fluctuations are considered and the results presented. The influence of the PDF of the particle separation on the concentration fluctuations is shown and discussed. We found that the separation PDF in the inertial subrange is not gaussian and this fact influences the predicted concentration fluctuations.
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Dopazo, César, Luis Valiño i Norberto Fueyo. "Statistical Description of the Turbulent Mixing of Scalar Fields". International Journal of Modern Physics B 11, nr 25 (10.10.1997): 2975–3014. http://dx.doi.org/10.1142/s0217979297001453.
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A formulation in terms of probability density function (PDF) transport equations is presented for inert and reactive scalar fields undergoing turbulen mixing. The PDF methodology is related to the classical moment equations. The hierarchy of PDF transport equations resembles the BBGKY equations in statistical mechanics. Closure hypothesis, approximating the molecular mixing term, are described and their predictions for simple systems are compared with direct numerical simulations (DNS). Solution algorithms in terms of Monte Carlo particles are also discussed.
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Hong, Zuu-Chang, i Ming-Hua Chen. "Statistical Model of a Self-Similar Turbulent Plane Shear Layer". Journal of Fluids Engineering 120, nr 2 (1.06.1998): 263–73. http://dx.doi.org/10.1115/1.2820643.
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A turbulence probability density function (pdf) equation model is employed to solve a self-similar turbulent plane shear layer. The proper similarity variable was introduced into the problem of interest to reduce the pdf equation into a spatially one-dimensional equation, which is still three dimensional in velocity space. Then the approximate moment method is employed to solve this simplified pdf equation. By the solutions of this equation, the various one-point mean quantities are immediatelly available. Agreement of the calculated mean velocity, turbulent energy and Reynolds stress with the available experimental data is generally satisfactory indicating that the pdf equation model and the moment method can quantitatively describe the statistics of free turbulence. Additionally, the balance of turbulence energy was calculated and discussed subsequently. It shows that the pdf methods are of more potential in revealing turbulence structure than conventional turbulence models.
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Chu, P. C., i L. M. Ivanov. "Statistical characteristics of irreversible predictability time in regional ocean models". Nonlinear Processes in Geophysics 12, nr 1 (28.01.2005): 129–38. http://dx.doi.org/10.5194/npg-12-129-2005.
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Abstract. Probabilistic aspects of regional ocean model predictability is analyzed using the probability density function (PDF) of the irreversible predictability time (IPT) (called τ-PDF) computed from an unconstrained ensemble of stochastic perturbations in initial conditions, winds, and open boundary conditions. Two-attractors (a chaotic attractor and a small-amplitude stable limit cycle) are found in the wind-driven circulation. Relationship between attractor's residence time and IPT determines the τ-PDF for the short (up to several weeks) and intermediate (up to two months) predictions. The τ-PDF is usually non-Gaussian but not multi-modal for red-noise perturbations in initial conditions and perturbations in the wind and open boundary conditions. Bifurcation of τ-PDF occurs as the tolerance level varies. Generally, extremely successful predictions (corresponding to the τ-PDF's tail toward large IPT domain) are not outliers and share the same statistics as a whole ensemble of predictions.
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Koricho, Mideksa Adugna, Girmaye Deye Dinsa i Nelisiwe Khuzwayo. "Cost-effectiveness of implementing performance-based financing for improving maternal and child health in Ethiopia". PLOS ONE 19, nr 7 (15.07.2024): e0305698. http://dx.doi.org/10.1371/journal.pone.0305698.
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Introduction Performance Based Financing (PBF) supports realization of universal health coverage by promoting bargaining between purchasers and health service providers through identifying priority services and monitoring indicators. In PBF, purchasers use health statistics and information to make decisions rather than merely reimbursing invoices. In this respect, PBF shares certain elements of strategic health purchasing. PBF implementation began in Ethiopia in 2015 as a pilot at one hospital and eight health centers. Prior to this the system predominantly followed input-based financing where providers were provided with a predetermined budget for inputs for service provision. The purpose of the study is to determine whether the implementation of PBF is cost-effective in improving maternal and child health in Ethiopia compared to the standard care. Methods The current study used cost-effectiveness analysis to assess the effects of PBF on maternal and child health. Two districts implementing PBF and two following standard care were selected for the study. Both groups of selected districts share common grounds before initiating PBF in the selected group. The provider perspective costing approach was used in the study. Data at the district level were gathered retrospectively for the period of July 2018 to June 2021. Data from health service statistics were transformed to population level coverages and the Lives Saved Tool method used to compute the number of lives saved. Additionally for purpose of comparison, lives saved were translated into discounted quality-adjusted life years. Results The number of lives saved under PBF was 261, whereas number of lives saved under standard care was 194. The identified incremental cost per capita due to PBF was $1.8 while total costs of delivering service at PBF district was 8,816,370 USD per million population per year while the standard care costs 9,780,920 USD per million population per year. QALYs obtained under PBF and standard care were 6,118 and 4,526 per million population per year, respectively. Conclusions The conclusion made from this analysis is that, implementing PBF is cost-saving in Ethiopia compared to the standard care. Limitations of the study Due to lack of district-level survey-based data, such as prevalence and effects on maternal and child health, national-level estimates were used into the LiST tool. There may be some central-level PBF start-up costs that were not captured, which may have spillover effects on the existing health system performance that this study has not considered. There may be health statistics data accuracy differences between the PBF and non-PBF districts. The researchers considered using data from records as reported by both groups of districts,
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Stechmann, Samuel N., i J. David Neelin. "First-Passage-Time Prototypes for Precipitation Statistics". Journal of the Atmospheric Sciences 71, nr 9 (28.08.2014): 3269–91. http://dx.doi.org/10.1175/jas-d-13-0268.1.
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Abstract Prototype models are presented for time series statistics of precipitation and column water vapor. In these models, precipitation events begin when the water vapor reaches a threshold value and end when it reaches a slightly lower threshold value, as motivated by recent observational and modeling studies. Using a stochastic forcing to parameterize moisture sources and sinks, this dynamics of reaching a threshold is a first-passage-time problem that can be solved analytically. Exact statistics are presented for precipitation event sizes and durations, for which the model predicts a probability density function (pdf) with a power law with exponent −. The range of power-law scaling extends from a characteristic small-event size to a characteristic large-event size, both of which are given explicitly in terms of the precipitation rate and water vapor variability. Outside this range, exponential scaling of event-size probability is shown. Furthermore, other statistics can be computed analytically, including cloud fraction, the pdf of water vapor, and the conditional mean and variance of precipitation (conditioned on the water vapor value). These statistics are compared with observational data for the transition to strong convection; the stochastic prototype captures a set of properties originally analyzed by analogy to critical phenomena. In a second prototype model, precipitation is further partitioned into deep convective and stratiform episodes. Additional exact statistics are presented, including stratiform rain fraction and cloud fractions, that suggest that even very simple temporal transition rules (for stratiform rain continuing after convective rain) can capture aspects of the role of stratiform precipitation in observed precipitation statistics.
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Boyle, Aoife, Cora Uhlemann, Oliver Friedrich, Alexandre Barthelemy, Sandrine Codis, Francis Bernardeau, Carlo Giocoli i Marco Baldi. "Nuw CDM cosmology from the weak-lensing convergence PDF". Monthly Notices of the Royal Astronomical Society 505, nr 2 (19.05.2021): 2886–902. http://dx.doi.org/10.1093/mnras/stab1381.
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ABSTRACT Pinning down the total neutrino mass and the dark energy equation of state is a key aim for upcoming galaxy surveys. Weak lensing is a unique probe of the total matter distribution whose non-Gaussian statistics can be quantified by the one-point probability distribution function (PDF) of the lensing convergence. We calculate the convergence PDF on mildly nonlinear scales from first principles using large-deviation statistics, accounting for dark energy and the total neutrino mass. For the first time, we comprehensively validate the cosmology dependence of the convergence PDF model against large suites of simulated lensing maps, demonstrating its per cent level precision and accuracy. We show that fast simulation codes can provide highly accurate covariance matrices, which can be combined with the theoretical PDF model to perform forecasts and eliminate the need for relying on expensive N-body simulations. Our theoretical model allows us to perform the first forecast for the convergence PDF that varies the full set of ΛCDM parameters. Our Fisher forecasts establish that the constraining power of the convergence PDF compares favourably to the two-point correlation function for a Euclid-like survey area at a single source redshift. When combined with a cosmic microwave background prior from Planck, the PDF constrains both the neutrino mass Mν and the dark energy equation of state w0 more strongly than the two-point correlation function.
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Mahata, Shibendu, Norbert Herencsar i David Kubanek. "On the Design of Power Law Filters and Their Inverse Counterparts". Fractal and Fractional 5, nr 4 (4.11.2021): 197. http://dx.doi.org/10.3390/fractalfract5040197.
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This paper presents the optimal modeling of Power Law Filters (PLFs) with the low-pass (LP), high-pass (HP), band-pass (BP), and band-stop (BS) responses by means of rational approximants. The optimization is performed for three different objective functions and second-order filter mother functions. The formulated design constraints help avoid placement of the zeros and poles on the right-half s-plane, thus, yielding stable PLF and inverse PLF (IPLF) models. The performances of the approximants exhibiting the fractional-step magnitude and phase responses are evaluated using various statistical indices. At the cost of higher computational complexity, the proposed approach achieved improved accuracy with guaranteed stability when compared to the published literature. The four types of optimal PLFs and IPLFs with an exponent α of 0.5 are implemented using the follow-the-leader feedback topology employing AD844AN current feedback operational amplifiers. The experimental results demonstrate that the Total Harmonic Distortion achieved for all the practical PLF and IPLF circuits was equal or lower than 0.21%, whereas the Spurious-Free Dynamic Range also exceeded 57.23 and 54.72 dBc, respectively.
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Pollak, Thomas H., i Linda M. Lampkin. "Nonprofit accountability and the National Center for Charitable Statistics". New Directions for Philanthropic Fundraising 2001, nr 31 (1.04.2001): 81–102. http://dx.doi.org/10.1002/pf.3105.
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