49 results on '"T. Madi"'
Search Results
2. Prediction of the remaining testing time for the generalized Pareto progressive censoring samples with applications to extreme hydrology events
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Fatemah Alqallaf, Mohamed T. Madi, Mohammad Z. Raqab, and Omar M. Bdair
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Statistics and Probability ,Multiple stages ,Bayes estimator ,021103 operations research ,Maximum likelihood ,0211 other engineering and technologies ,Model parameters ,02 engineering and technology ,01 natural sciences ,010104 statistics & probability ,Generalized Pareto distribution ,Censoring (clinical trials) ,Statistics ,Econometrics ,0101 mathematics ,Importance sampling ,Mathematics - Abstract
The prediction of the unobserved units is typically based on the derivations of the predictive distributions of the individual observations. This technique is of little interest when one wishes to predict a function of missing or unobserved data such as the remaining testing time. In this article, based on a progressive type-II censored sample from the generalized Pareto (GP) distribution, we consider the problem of predicting times to failure of units in multiple stages. Importance sampling is used to estimate the model parameters, and Gibbs and Metropolis samplers are used to predict the testing times of the removed unfailed units. Data analyses involving the water-level exceedances by the River Nidd in North Yorkshire, England, have been performed and predictions of the total remaining level exceedances are discussed.
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- 2017
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3. Recalibration of U-doped standard glasses through uranium thin film for neutron-fluence measurements
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Julio C. Hadler, C.A. Tello, A. L. Lixandrão-Filho, P.T.D. Siqueira, Raymond Jonckheere, E.A.C. Curvo, Sandro Guedes, Carlos José Soares, and T. Madi Filho
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Neutron monitor ,Materials science ,Health, Toxicology and Mutagenesis ,Public Health, Environmental and Occupational Health ,chemistry.chemical_element ,Mineralogy ,Actinide ,Uranium ,Natural uranium ,Pollution ,Apatite ,Analytical Chemistry ,Nuclear Energy and Engineering ,chemistry ,Neutron flux ,visual_art ,visual_art.visual_art_medium ,Radiology, Nuclear Medicine and imaging ,Neutron ,Radiometric dating ,Spectroscopy - Abstract
This work presents a recalibration of U-doped standard glasses using natural uranium thin films to be used as most dedicated neutron monitor for fission-track dating. The recalibrated U-doped glasses were used to determine fission-track ages in apatite samples from Brazilian alkaline formations (Alto Paranaiba) and standard Durango apatite. Samples were irradiated in two nuclear reactors with different characteristics and the results were compared. For well-thermalized neutron facility, metal activation monitor was also used. The ages of Alto Paranaiba arch and Durango apatite agree with those determined by other radiometric dating methods and metal activation monitors. These results suggest that the presented recalibration is suitable to be used routinely for fission-track dating studies even in a non-well thermalized neutron facility.
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- 2014
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4. Career Exploration and Perceived Employability within an Emerging Economy Context
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Hassan M. Selim, Yehuda Baruch, Ingo Forstenlechner, and Mohamed T. Madi
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Organizational Behavior and Human Resource Management ,Labour economics ,Economic growth ,Social contract ,business.industry ,Strategy and Management ,media_common.quotation_subject ,Public sector ,Context (language use) ,Employability ,Private sector ,State (polity) ,Work (electrical) ,Management of Technology and Innovation ,Economics ,Emerging markets ,business ,Applied Psychology ,media_common - Abstract
Following four decades of unprecedented economic, social, and cultural change, the United Arab Emirates labor market is highly segmented: The native population is almost exclusively employed in the government sector, while the private sector is effectively outsourced to foreigners. This has created an unsustainable situation with growing numbers of young citizens reaching working age and with a public sector that has reached the saturation point. Policymakers repeatedly try to legislate to encourage private-sector employers to hire citizens. These policies have had limited success. We explored the career attitudes of 2,267 United Arab Emirates citizens prior to their entry into the labor market. Using structural equation modeling, we found that the social contract and resulting expectations toward state employment have strong implications for willingness to work in the private sector
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- 2014
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5. In-situ kinetics of modifications induced by swift heavy ions in Al 2 O 3 : Colour centre formation, structural modification and amorphization
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Clara Grygiel, T. Been, M. Sall, D. Marie, T. Madi, Isabelle Monnet, F. Moisy, Emmanuel Balanzat, Henning Lebius, Matériaux, Défauts et IRradiations (MADIR), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)
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Materials science ,Polymers and Plastics ,chemistry.chemical_element ,02 engineering and technology ,01 natural sciences ,Ion ,Xenon ,Swift heavy ion ,Phase stability ,0103 physical sciences ,Irradiation ,Phase transformations ,010302 applied physics ,Ion track ,Krypton ,Metals and Alloys ,021001 nanoscience & nanotechnology ,Crystallographic defect ,Electronic, Optical and Magnetic Materials ,X-ray diffraction ,chemistry ,Ion irradiation ,Ceramics and Composites ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Colour centre ,Atomic physics ,0210 nano-technology - Abstract
International audience; This paper details in-situ studies of modifications induced by swift heavy ion irradiation in a-Al2O3. This complex behaviour is intermediary between the behaviour of amorphizable and non-amorphizable materials, respectively. A unique combination of irradiation experiments was performed at the IRRSUD beam line of the GANIL facility, with three different characterisation techniques: in-situ UVeVis absorption, in-situ grazing incidence X-Ray diffraction and ex-situ transmission electron microscopy. This allows a complete study of point defects, and by depth profile of structural and microstructural modifications created on the trajectory of the incident ion. The a-Al2O3 crystals have been irradiated by 92 MeV Xenon and 74 MeV Krypton ions, the irradiation conditions have been chosen rather similar with an energy range where the ratio between electronic and nuclear stopping power changes dramatically as function of depth penetration. The main contribution of electronic excitation, above the threshold for track formation, is present beneath the surface to finally get almost only elastic collisions at the end of the projected range. Amorphization kinetics by the overlapping of multiple ion tracks is observed. In the crystalline matrix, long range strains, unit-cell swelling, local microstrain, domain size decrease, disordering of oxygen sublattice as well as colour centre formation are found. This study highlights the relationship between ion energy losses into a material and its response. While amorphization requires electronic stopping values above a certain threshold, point defects are predominantly induced by elastic collisions, while some structural modifications of the crystalline matrix, such as unit-cell swelling, are due to contribution of both electronic and nuclear processes.
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- 2017
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6. Emiratisation: determining the factors that influence the recruitment decisions of employers in the UAE
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Emilie Rutledge, Ingo Forstenlechner, Hassan M. Selim, and Mohamed T. Madi
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Organizational Behavior and Human Resource Management ,Labour economics ,Reservation wage ,Order (business) ,Management of Technology and Innovation ,Strategy and Management ,Industrial relations ,Economics ,Business and International Management ,Private sector - Abstract
The Arab Gulf's labour market is being overhauled. The private sector is increasingly being ‘obliged’ to more actively support nationalisation programmes. This study seeks to quantitatively determine the recruitment decisions of the employers. We collated the views of just under 250 UAE-based HRM personnel, in order to identify which factors (social, cultural, economic, regulatory, educational and motivational) are most significant as cited in the relevant literature. Not having the necessary educational qualifications and high reservation wage demands were found to have less of a bearing than does the perceived lack of vocationally orientated motivation and the ambiguities over the differing rights afforded to employees.
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- 2012
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7. Inference for the generalized Rayleigh distribution based on progressively censored data
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Mohamed T. Madi and Mohammad Z. Raqab
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Statistics and Probability ,Bayes estimator ,Scale (ratio) ,Rayleigh distribution ,Applied Mathematics ,Bayesian probability ,Inference ,Sample (statistics) ,Statistics::Computation ,Distribution (mathematics) ,Statistics ,Statistics::Methodology ,Statistics, Probability and Uncertainty ,Importance sampling ,Mathematics - Abstract
In this paper, and based on a progressive type-II censored sample from the generalized Rayleigh (GR) distribution, we consider the problem of estimating the model parameters and predicting the unobserved removed data. Maximum likelihood and Bayesian approaches are used to estimate the scale and shape parameters. The Gibbs and Metropolis samplers are used to predict the life lengths of the removed units in multiple stages of the progressively censored sample. Artificial and real data analyses have been performed for illustrative purposes.
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- 2011
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8. Step-Stress Accelerated Life Tests.
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Mohamed T. Madi
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- 2011
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9. Generalized Rayleigh Distribution.
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Mohammad Z. Raqab and Mohamed T. Madi
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- 2011
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10. IGLIAS: A new experimental set-up for low temperature irradiation studies at large irradiation facilities
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Marin Chabot, Philippe Boduch, P. Voivenel, T. Been, Emmanuel Dartois, J.M. Ramillon, T. Madi, B. Augé, F. Ropars, Hermann Rothard, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut des Sciences Moléculaires d'Orsay (ISMO), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
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Materials science ,Condensation ,Analytical chemistry ,02 engineering and technology ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,Mass spectrometry ,01 natural sciences ,Ion ,Ultraviolet visible spectroscopy ,0103 physical sciences ,Quadrupole ,[PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det] ,Irradiation ,Fourier transform infrared spectroscopy ,0210 nano-technology ,010303 astronomy & astrophysics ,Instrumentation - Abstract
International audience; We designed and built a mobile experimental set-up for studying the interaction of ion beams with solid samples in a wide temperature range from 9 to 300 K. It is either possible to mount up to three samples prepared ex situ or to prepare samples by condensation of molecules from gases or vapours onto IR or Visible-ultraviolet (Vis-UV) transparent windows. The physico-chemical evolution during irradiation can be followed in situ with different analysis techniques including Fourier transform infrared spectroscopy, Vis-UV, and quadrupole mass spectrometry.
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- 2018
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11. A note on the equivariant estimation of an exponential scale using progressively censored data
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Mohamed T. Madi
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Statistics and Probability ,Exponential distribution ,Mean squared error ,Estimation theory ,Applied Mathematics ,Estimator ,Minimum-variance unbiased estimator ,Statistics ,Applied mathematics ,Equivariant map ,Statistics, Probability and Uncertainty ,Minimax estimator ,Scale parameter ,Mathematics - Abstract
We consider the problem of estimating the scale parameter θ of the shifted exponential distribution with unknown location based on a type II progressively censored sample. Under a large class of bowl-shaped loss functions, a smooth estimator, that dominates the minimum risk equivariant estimator of θ , is proposed. A numerical study is performed and shows that the improved estimator yields significant risk reduction over the MRE.
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- 2010
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12. Bayesian Inference for the Generalized Exponential Distribution Based on Progressively Censored Data
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Mohamed T. Madi and Mohammad Z. Raqab
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Statistics and Probability ,Bayes estimator ,Exponential distribution ,Estimation theory ,Bayesian inference ,Statistics::Computation ,Exponential function ,symbols.namesake ,Statistics ,symbols ,Scale parameter ,Importance sampling ,Mathematics ,Gibbs sampling - Abstract
Based on a progressively Type-II censored sample, Bayesian estimation of the parameters as well as Bayesian prediction of the unobserved failure times from the generalized exponential (GE) distribution are studied. Importance sampling is used to estimate the scale and shape parameters. The Gibbs and Metropolis samplers are considered for predicting times to failure of units in multiple stages. A numerical simulation study involving three data sets is presented to illustrate the methods of estimation and prediction.
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- 2009
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13. Estimation ofP(Y < X) for the Three-Parameter Generalized Exponential Distribution
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Mohammad Z. Raqab, Debasis Kundu, and Mohamed T. Madi
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Statistics and Probability ,Bayes estimator ,Exponential distribution ,Location parameter ,Statistics ,Applied mathematics ,Likelihood function ,Scale parameter ,Random variable ,Importance sampling ,Shape parameter ,Mathematics - Abstract
This article considers the estimation of R = P(Y
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- 2008
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14. Improved estimation of an exponential scale ratio based on records
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Mohamed T. Madi
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Statistics and Probability ,Independent and identically distributed random variables ,Exponential distribution ,Probability theory ,Mean squared error ,Statistics ,Estimator ,Statistics, Probability and Uncertainty ,Random variable ,Scale parameter ,Mathematics ,Exponential function - Abstract
We consider the problem of estimating the ratio θ of the scale parameters of two shifted exponential distributions with unknown shifts, based on two independent samples of records drawn from sequential samples of independent and identically distributed random variables. Under a large class of bowl-shaped loss functions, the best affine equivariant estimator (BAEE) of θ is shown to be inadmissible. Four new classes of dominating procedures are proposed. A numerical study is performed to show the extent of risk reduction that the improved estimators provide over the BAEE.
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- 2008
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15. Bayesian prediction of rainfall records using the generalized exponential distribution
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Mohamed T. Madi and Mohammad Z. Raqab
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Statistics and Probability ,Bayes estimator ,Exponential distribution ,Statistics::Applications ,Ecological Modeling ,Rejection sampling ,Bayesian probability ,Statistics::Computation ,symbols.namesake ,Statistics ,symbols ,Bayesian linear regression ,Importance sampling ,Parametric statistics ,Gibbs sampling ,Mathematics - Abstract
SUMMARY The Los Angeles rainfall data are found to fit well to the two-parameter generalized exponential (GE) distribution. A Bayesian parametric approach is described and used to predict the behavior of further rainfall records. Importance sampling is used to estimate the model parameters, and the Gibbs and Metropolis samplers are used to implement the prediction procedure. Copyright © 2007 John Wiley & Sons, Ltd.
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- 2007
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16. Decision theoretic estimation using record statistics
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Mohamed T. Madi
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Statistics and Probability ,Independent and identically distributed random variables ,Reduction (complexity) ,Exponential distribution ,Mean squared error ,Statistics ,Estimator ,Equivariant map ,Affine transformation ,Statistics, Probability and Uncertainty ,Scale parameter ,Mathematics - Abstract
We consider the problem of estimating the scale parameter θ of the shifted exponential distribution with unknown shift based on a set of observed records drawn from a sequential sample of independent and identically distributed random variables. Under a large class of bowl-shaped loss functions, the best affine equivariant estimator (BAEE) of θ is shown to be inadmissible. Two dominating procedures are proposed. A numerical study is performed to show the extent of risk reduction that the improved estimators provide over the BAEE.
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- 2005
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17. Bayesian inference for the generalized exponential distribution
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Mohamed T. Madi and Mohamed Z. Raqab
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Statistics and Probability ,Inverse-chi-squared distribution ,Applied Mathematics ,symbols.namesake ,Modeling and Simulation ,Generalized beta distribution ,Statistics ,Gamma distribution ,symbols ,Generalized integer gamma distribution ,Applied mathematics ,Statistics, Probability and Uncertainty ,Natural exponential family ,Probability integral transform ,Bayesian linear regression ,Mathematics ,Gibbs sampling - Abstract
The two-parameter generalized exponential (GE) distribution was introduced by Gupta and Kundu [Gupta, R.D. and Kundu, D., 1999, Generalized exponential distribution. Australian and New Zealand Journal of Statistics, 41(2), 173–188.]. It was observed that the GE can be used in situations where a skewed distribution for a nonnegative random variable is needed. In this article, the Bayesian estimation and prediction for the GE distribution, using informative priors, have been considered. Importance sampling is used to estimate the parameters, as well as the reliability function, and the Gibbs and Metropolis samplers data sets are used to predict the behavior of further observations from the distribution. Two data sets are used to illustrate the Bayesian procedure.
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- 2005
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18. Bayesian prediction of temperature records using the Pareto model
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Mohamed T. Madi and Mohamed Z. Raqab
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Statistics and Probability ,Independent and identically distributed random variables ,Ecological Modeling ,Bayesian probability ,Pareto principle ,Sampling (statistics) ,Sample (statistics) ,Data set ,symbols.namesake ,Statistics ,symbols ,Pareto distribution ,Mathematics ,Gibbs sampling - Abstract
Statistical prediction of record values has potential environmental applications dealing, for example, with abrupt climate jumps, such as the prediction of rainfall extremes, highest water levels and sea surface or air record temperatures. In this article, and on the basis of observed Pareto records drawn from a sequential sample of independent and identically distributed random variables, we address the problem of Bayesian prediction of future records. The Bayesian predictive distribution is developed for future records and the corresponding highest posterior density (HPD)-prediction intervals are established. A data set representing the record values of average July temperatures in Neuenburg, Switzerland, is used to illustrate the proposed prediction procedure's environmental application. Copyright © 2004 John Wiley & Sons, Ltd.
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- 2004
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19. Bayesian prediction of the total time on test using doubly censored rayleigh data
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Mohamed T. Madi and Mohamed Z. Raqab
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Statistics and Probability ,Rayleigh distribution ,Applied Mathematics ,Bayesian probability ,Order statistic ,Posterior probability ,Sample (statistics) ,symbols.namesake ,Modeling and Simulation ,Statistics ,Prior probability ,symbols ,Statistics, Probability and Uncertainty ,Mathematics ,Gibbs sampling ,Statistical hypothesis testing - Abstract
In a Bayesian setting, and on the basis of a doubly censored random sample of failure times drawn from a Rayleigh distribution, Fernandez (2000, Statist. Probab. Lett. , 48 , 393-399) considered the problem of predicting an independent future sample from the same distribution. In this article, we extend his work to include the estimation of the predictive distribution of the total time on test up to a certain failure in a future sample, as well as that of the remaining testing time time until all the items in the original sample have failed. Two examples are used to illustrate the prediction procedure.
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- 2002
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20. On the invariant estimation of an exponential scale using doubly censored data
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Mohamed T. Madi
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Statistics and Probability ,Exponential distribution ,Mean squared error ,Statistics ,Monotone likelihood ratio ,Equivariant map ,Applied mathematics ,Estimator ,Statistics, Probability and Uncertainty ,Invariant (mathematics) ,Scale parameter ,Exponential function ,Mathematics - Abstract
We consider the problem of estimating the scale parameter θ of the shifted exponential distribution with unknown shift based on a doubly censored sample from this distribution. Under squared error loss, Elfessi (Statist. Probab. Lett. 36 (1997) 251) has shown that the best affine equivariant estimator (BAEE) of θ is inadmissible. A smoother dominating procedure is proposed. The new improved estimator is shown, via a numerical study, to provide more significant risk reductions over the BAEE.
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- 2002
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21. Measurements and 3D Monte Carlo simulation of MeV ion transmission through conical glass capillaries
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C L Zhou, M.J. Simon, Abdenacer Benyagoub, Henning Lebius, A. Méry, Arnold Milenko Müller, T. Madi, Isabelle Monnet, Max Döbeli, Haruo Shiromaru, Amine Cassimi, S. Guillous, H.-A. Synal, Clara Grygiel, Ion Beam Physics [ETH Zürich], Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Tokyo Metropolitan University [Tokyo] (TMU), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
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010302 applied physics ,Elastic scattering ,[PHYS]Physics [physics] ,Nuclear and High Energy Physics ,Materials science ,Capillary action ,Monte Carlo method ,Conical surface ,01 natural sciences ,Collimated light ,Ion ,0103 physical sciences ,Physics::Accelerator Physics ,Atomic physics ,010306 general physics ,Instrumentation ,Current density ,Beam (structure) ,ComputingMilieux_MISCELLANEOUS - Abstract
To investigate possible beam guiding and current density enhancement properties for conical glass capillaries for MeV ions transmission measurements with well collimated ion beams of 1 MeV He+ and 71 MeV Xe 19+ were done. No guiding effect was observed and only decent enhancement factors e between 1 and 2 were measured and attributed to scattered particles. A 3D Monte Carlo simulation which is based on SRIM code was developed. The simulation reproduces the experimental results very well. This shows that the transmission properties of capillaries for MeV ion beams are governed by simple elastic scattering of the ions in the glass of the capillary. © 2014 Elsevier B.V. All rights reserved.
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- 2014
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22. Bayes inference for treatment effects with uncertain order constraints
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Tom Leonard, Mohamed T. Madi, and Kam-Wah Tsui
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Statistics and Probability ,Flexibility (engineering) ,Mathematical optimization ,Posterior probability ,Inference ,Variance (accounting) ,Constraint (information theory) ,Bayes' theorem ,symbols.namesake ,Prior probability ,symbols ,Econometrics ,Statistics, Probability and Uncertainty ,Mathematics ,Gibbs sampling - Abstract
Constrained parameter situations arise in a wide variety of practical problems and the corresponding order restricted inference has been extensively researched. In previous work, order restrictions have always been imposed on the estimates of the ordered parameters, the data may, however, provide strong evidence that the constraints are untrue, in which case it might be more sensible for the estimates to contradict the constraints, or to compromise between unconstrained estimates and estimates based on the constraint. In this paper, we consider finite sample inference for the one-way layout normal means problem with unknown common variance and we assume that the treatment means are hypothesized to be ordered but with a degree of uncertainty in this hypothesis via prior assumptions that we express. This flexibility will permit the data to play a more substantive role in the inferential procedure. The posterior distribution of the treatment means is estimated using the Gibbs sampler. An illustrative analysis using a real data set is provided.
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- 2000
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23. Bayesian inference for partially accelerated life tests using Gibbs sampling
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Mohamed T. Madi
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Mathematical optimization ,Life length ,Computer science ,business.industry ,Monte Carlo method ,Estimator ,Sampling (statistics) ,Failure rate ,Condensed Matter Physics ,Bayesian inference ,Atomic and Molecular Physics, and Optics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,symbols.namesake ,Bayes' theorem ,symbols ,Artificial intelligence ,Electrical and Electronic Engineering ,Safety, Risk, Reliability and Quality ,business ,Gibbs sampling - Abstract
We consider a life testing situation in which several groups of items are put, at different instances, on the partially accelerated life test proposed by DeGroot and Goel [Naval Research Logistics Quarterly, 1979. 26, 223–235]. The combined failure time data are then used to derive empirical Bayes estimators for the failure of the exponential life length under normal conditions. The estimation which is implemented using the Gibbs sampler Monte-Carlo-based approach, illustrates once again the ease with which these new types of estimation problems often requiring sophisticated numerical or analytical expertise, can be handled using the sampling based approach.
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- 1997
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24. Bayes and stein estimation under asymmetric loss functions:a numerical risk comparison
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Mohamed T. Madi
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Statistics and Probability ,Normal distribution ,Bayes estimator ,Efficient estimator ,Modeling and Simulation ,Statistics ,Stein's unbiased risk estimate ,Estimator ,Stein's example ,Scale parameter ,Invariant estimator ,Mathematics - Abstract
We consider the estimation of the scale parameter of the shifted exponential distribution and the variance of the normal distribution when the locations of these distributions are unknown and when loss is measured by invariant asymmetric loss functions. Stein type and Bayesian estimators are derived and compared in terms of risk improvements over the best affine equivariant estimator (BAEE). It is demonstrated that, under asymmetric loss, Bayes estimators provide a much larger degree of improvement over the BAEE than Stein estimators.
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- 1997
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25. Bayesian estimation for shifted exponential distributions
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Mohamed T. Madi and Tom Leonard
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Statistics and Probability ,Bayes estimator ,Exponential distribution ,Location parameter ,Applied Mathematics ,Monte Carlo method ,Bayesian probability ,Estimator ,Exponential function ,Statistics ,Applied mathematics ,Statistics, Probability and Uncertainty ,Scale parameter ,Mathematics - Abstract
Consider m random samples which are independently drawn from m shifted exponential distributions, with respective location parameters θ1, θ2, …, θm and common scale parameter σ. On the basis of the given samples and in a Bayesian framework, we address the problem of estimating the scale parameter σ and the parametric function γ = ∑mi=1 aiθi + bσ. Our proposed Bayesian estimators are compared, via a Monte Carlo study, to the invariant estimators proposed by Madi and Tsui (1990) and Rukhin and Zidek (1985) in terms of risk improvements on the best affine equivariant estimators.
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- 1996
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26. SPORT: A new sub-nanosecond time-resolved instrument to study swift heavy ion-beam induced luminescence - Application to luminescence degradation of a fast plastic scintillator
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F. Ropars, Amine Cassimi, T. Madi, B. Ban-d’Etat, Isabelle Monnet, Jean Marc Ramillon, Clara Grygiel, Emmanuel Balanzat, Henning Lebius, Emmanuel Gardés, F. Durantel, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Time-resolved spectroscopy ,Nuclear and High Energy Physics ,Materials science ,Physics - Instrumentation and Detectors ,Physics::Instrumentation and Detectors ,[SDE.MCG]Environmental Sciences/Global Changes ,FOS: Physical sciences ,02 engineering and technology ,Ion-beam induced luminescence ,Scintillator ,01 natural sciences ,Ion ,Swift heavy ion irradiation ,Swift heavy ion ,0103 physical sciences ,[SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology ,Stopping power (particle radiation) ,Irradiation ,Instrumentation ,Quenching ,Radiation hardness ,Plastic scintillator ,Scintillation ,Condensed Matter - Materials Science ,010308 nuclear & particles physics ,Radiochemistry ,Materials Science (cond-mat.mtrl-sci) ,Instrumentation and Detectors (physics.ins-det) ,021001 nanoscience & nanotechnology ,Atomic physics ,0210 nano-technology ,Luminescence - Abstract
We developed a new sub-nanosecond time-resolved instrument to study the dynamics of UV-visible luminescence under high stopping power heavy ion irradiation. We applied our instrument, called SPORT, on a fast plastic scintillator (BC-400) irradiated with 27-MeV Ar ions having high mean electronic stopping power of 2.6 MeV/\mu m. As a consequence of increasing permanent radiation damages with increasing ion fluence, our investigations reveal a degradation of scintillation intensity together with, thanks to the time-resolved measurement, a decrease in the decay constant of the scintillator. This combination indicates that luminescence degradation processes by both dynamic and static quenching, the latter mechanism being predominant. Under such high density excitation, the scintillation deterioration of BC-400 is significantly enhanced compared to that observed in previous investigations, mainly performed using light ions. The observed non-linear behaviour implies that the dose at which luminescence starts deteriorating is not independent on particles' stopping power, thus illustrating that the radiation hardness of plastic scintillators can be strongly weakened under high excitation density in heavy ion environments., Comment: 5 figures, accepted in Nucl. Instrum. Methods B
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- 2013
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27. On the invariant estimation of a normal variance ratio
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Mohamed T. Madi
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Statistics and Probability ,Estimation ,Reduction (complexity) ,Applied Mathematics ,Statistics ,Estimator ,Equivariant map ,Magnitude (mathematics) ,Affine transformation ,Statistics, Probability and Uncertainty ,Invariant (mathematics) ,Variance ratio ,Mathematics - Abstract
We consider the estimation of the variance ratio of two normal populations with unknown means. Two smooth estimators that improve on the best affine equivariant estimator (BAEE), under a large class of bowl-shaped loss functions, are derived. A numerical study is performed to get a feel for the magnitude of risk reduction when these estimators are used instead of the BAEE.
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- 1995
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28. Online in situ x-ray diffraction setup for structural modification studies during swift heavy ion irradiation
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D. Lelievre, Clara Grygiel, Patrick Guinement, Jean-Marc Ramillon, S. Bouffard, Henning Lebius, T. Been, Isabelle Monnet, S. Guillous, T. Madi, and A. Quentin
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010302 applied physics ,Diffraction ,Phase transition ,Condensed Matter - Materials Science ,Materials science ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Molecular physics ,3. Good health ,Ion ,Condensed Matter::Materials Science ,Swift heavy ion ,0103 physical sciences ,X-ray crystallography ,Irradiation ,Crystallite ,0210 nano-technology ,Instrumentation ,Diffractometer - Abstract
The high energy density of electronic excitations due to the impact of swift heavy ions can induce structural modifications in materials. We present a X-ray diffractometer called ALIX, which has been set up at the low-energy IRRSUD beamline of the GANIL facility, to allow the study of structural modification kinetics as a function of the ion fluence. The X-ray setup has been modified and optimized to enable irradiation by swift heavy ions simultaneously to X-ray pattern recording. We present the capability of ALIX to perform simultaneous irradiation - diffraction by using energy discrimination between X-rays from diffraction and from ion-target interaction. To illustrate its potential, results of sequential or simultaneous irradiation - diffraction are presented in this article to show radiation effects on the structural properties of ceramics. Phase transition kinetics have been studied during xenon ion irradiation of polycrystalline MgO and SrTiO3. We have observed that MgO oxide is radiation-resistant to high electronic excitations, contrary to the high sensitivity of SrTiO3, which exhibits transition from the crystalline to the amorphous state during irradiation. By interpreting the amorphization kinetics of SrTiO3, defect overlapping models are discussed as well as latent track characteristics. Together with a transmission electron microscopy study, we conclude that a single impact model describes the phase transition mechanism., 12 pages, 8 figures, Accepted to Review of Scientific Instruments
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- 2012
29. Software project effort: Different methods of estimation
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Khaled Hamdan and Mohamed T. Madi
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Social software engineering ,Cost estimate ,Computer science ,business.industry ,Team software process ,Software development ,Engineering management ,Software analytics ,Software ,Personal software process ,Software verification and validation ,Project management ,business ,Software project management ,Simulation ,Project management triangle - Abstract
This work is concerned with the measure and, most importantly, the prediction of software development projects in terms of cost estimate. The purpose of this paper is to explore the usefulness of recording, in the software project data, the cultural and leadership characteristics of the development team. As a result of the study, a new model for identifying and analyzing was developed. The paper tests the association of these characteristics with the other project characteristics using data from a survey of 41 software projects collected from IT organizations in UAE.
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- 2011
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30. Alternative estimators for the variance of several normal populations
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Mohamed T. Madi
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Statistics and Probability ,Reduction (complexity) ,Normal distribution ,Estimation theory ,Statistics ,Estimator ,Equivariant map ,Magnitude (mathematics) ,Variance (accounting) ,Statistics, Probability and Uncertainty ,Parameter space ,Mathematics - Abstract
The problem of interest is to estimate the common variance of k (k ⩾ 2) normal populations with possibly different means, based on k independent samples from these populations. Improved estimators over the usual estimator under a large class of bowl-shaped loss functions are proposed. These estimators are similar to those of Brewster and Zidek (1974). However, the regions of the parameter space over which these estimators have the most reduction in risk and the magnitude of risk reduction over the usual estimator are different than those of Brewster and Zidek.
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- 1993
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31. Multiple step-stress accelerated life test: the tampered failure rate model
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Mohamed T. Madi
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Statistics and Probability ,Maximum likelihood ,Statistics ,Failure rate ,Step stress ,Life test ,Reliability (statistics) ,Accelerated life testing ,Mathematics ,Weibull distribution ,Parametric statistics - Abstract
Battacharyya and Soejoeti (1989) proposed the tampered failure rate model for step-stress accelerated life testing. In this note, their model is generalized from the simple (2-step) step-stress setting to the multiple (k-step, k > 2) setting. For the parametric setting where the life distribution under constant stress is Weibull, maximum likelihood estimation is investigated and the situation where the different stress levels are equispaced is looked at.
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- 1993
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32. Development of a fourth generation industrial tomography for multiphase systems analysis
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F.E. Costa, T. Madi Filho, Carlos Henrique de Mesquita, Diego V. S. Carvalho, C. R. Dantas, Pablo A.S. Vasquez, and Margarida Mizue Hamada
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Engineering ,business.industry ,Preamplifier ,Amplifier ,Detector ,Electrical engineering ,High voltage ,Signal ,Photodiode ,law.invention ,Data acquisition ,Optics ,law ,business ,Electronic circuit - Abstract
In the present work a 4D (three dimensions combined with the time) fourth generation CT system was developed with several detectors (as much as required) made with CsI (Tl) size of 5 mm × 20 mm width × length) coupled to PIN photodiodes size of 5×5 mm2. It was also developed a pulse sensitive preamplifier in a small electronic circuit board with size of 9.5×100 mm2 (width × length). This system was able to identify 80 keV photopeak at room temperature and was obtained a photo peak counting efficiency around 33% for 137Cs. The proposed CT was assembled on a wooden platform, where the cylindrical detectors (photodiode + preamplifier + CsI (Tl) crystal) are arranged in pentagonal parallel or fan sectors. Five sources of 137Cs or jointly with 133Ba or 192Ir are assembled at the vertices. Each detector was supplied with three power supplies: +12V,−12V and adjustable high voltage HV (capable to range from 0 to 2000V). The pre-amplifier signal was connected to a data acquisition unit containing amplifier, counter unit and transfer data via USB-2 cable to a computer type PC-Windows. The system was easily adaptable to the environment of the industries and able to produce multi-phase analysis in real time.
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- 2010
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33. Study of a Li doped CsI scintillator crystal as a neutron detector
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Filho, T Madi, primary, Pereira, M C C, additional, Berretta, J R, additional, and Cárdenas, J P N, additional
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- 2015
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34. Cerebral organoids as a tool to model neurological diseases
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T. Madikas and G. Dafnopoulos
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cell biology ,organoids ,developmental biology ,neurobiology ,Science - Abstract
Modeling the human brain in order to study its physiology, development and diseases has been very challenging due to its structural and functional complexity and fragility. Brain organoids, derived from human pluripotent stem cells, opened a new approach to create in vitro 3D models, that more closely resemble the complexity of the brain, as compared to 2D cell cultures. So far, multiple developmental and neurodegenerative diseases have been generated with organoid technology and used as drug screening platforms not only to accelerate the development of more efficient treatments but also to get one step closer to personalized medicine. This review aims to showcase the current applications of brain organoids and review future perspectives and limitations.
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- 2022
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35. On the invariant estimation of an exponential scale using doubly censored data
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T. Madi, Mohamed, primary
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- 2002
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36. Circulating microRNA’s as a diagnostic tool for hepatocellular carcinoma in a hyper endemic HIV setting, KwaZulu-Natal, South Africa: a case control study protocol focusing on viral etiology
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K. Sartorius, B. Sartorius, A. Kramvis, E. Singh, A. Turchinovich, B. Burwinkel, T. Madiba, and C. A. Winkler
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Hepatocellular carcinoma ,miRNA ,Biomarker ,Diagnosis ,Staging ,HBV ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background A wide range of studies has investigated the diagnostic proficiency of extracellular microRNAs (miRNAs) in hepatocellular cancer (HCC). HCC is expected to increase in Sub-Saharan Africa (SSA), due to endemic levels of viral infection (HBV/HIV), ageing and changing lifestyles. This unique aetiological background provides an opportunity for investigating potentially novel circulating miRNAs as biomarkers for HCC in a prospective study in South Africa. Methods This study will recruit HCC patients from two South African cancer hospitals, situated in Durban and Pietermaritzburg in the province of KwaZulu-Natal. These cases will include both HBV mono-infected and HBV/HIV co-infected HCC cases. The control group will consist of two (2) age and sex-matched healthy population controls per HCC case randomly selected from a Durban based laboratory. The controls will exclude patients if they have any evidence of chronic liver disease. A standardised reporting approach will be adopted to detect, quantify and normalize the level of circulating miRNAs in the blood sera of HCC cases and their controls. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) will be employed to quantity extracellular miRNAs. Differences in concentration of relevant miRNA by case/control status will be assessed using the Wilcoxon rank-sum (Mann-Whitney U) test. Adjustment for multiple testing (Bonferroni correction), receiver operating curves (ROC) and optimal breakpoint analyses will be employed to identify potential thresholds for the differentiation of miRNA levels of HCC cases and their controls. Discussion Although there is a growing base of literature regarding the role of circulating miRNAs as biomarkers, this promising field remains a ‘work in progress’. The aetiology of HBV infection in HCC is well understood, as well as it’s role in miRNA deregulation, however, the mediating role of HIV infection is unknown. HCC incidence in SSA, including South Africa, is expected to increase significantly in the next decade. A combination of factors, therefore, offers a unique opportunity to identify candidate circulating miRNAs as potential biomarkers for HBV/HIV infected HCC.
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- 2017
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37. Development of neutron detector using the surface barrier sensor with polyethylene (n, p) and 10B (n,a) converters
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Filho, T. Madi, Hamada, M. M., Shiraishi, F., and Mesquita, C. Henrique de
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- 2001
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38. Study of a Li doped CsI scintillator crystal as a neutron detector.
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T Madi Filho, M C C Pereira, J R Berretta, and J P N Cárdenas
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- 2015
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39. Four years after the implementation of antimicrobial stewardship program in Jordan: evaluation of program's core elements.
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Hassan SK, Dahmash EZ, Madi T, Tarawneh O, Jomhawi T, Alkhob W, Ghanem R, and Halasa Z
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- Cross-Sectional Studies, Jordan, Hospitals, Public, Antimicrobial Stewardship methods, Anti-Infective Agents therapeutic use
- Abstract
Objectives: To combat antimicrobial resistance, the World Health Organization (WHO) urged healthcare organizations in Low- and Middle-Income Countries (LMICs) to implement the core elements of the antimicrobial stewardship (AMS) programs. In response, Jordan took action and developed a national antimicrobial resistance action plan (NAP) in 2017 and commenced the AMS program in all healthcare facilities. It is paramount to evaluate the efforts to implement the AMS programs and understand the challenges of implementing a sustainable and effective program, in Low-Middle Income Country (LMIC) contexts. Therefore, the aim of this study was to appraise the compliance of public hospitals in Jordan to the WHO core elements of effective AMS programs after 4 years of commencement., Methods: A cross-sectional study in public hospitals in Jordan, using the WHO AMS program core elements for LMICs was carried out. The questionnaire comprised 30 questions that covered the program's six core elements: leadership commitment, accountability and responsibility, AMS actions, education and training, monitoring, and evaluation, and reporting and feedback. A five-point Likert scale was employed for each question., Results: A total of 27 public hospitals participated, with a response rate of 84.4%. Adherence to core elements ranged from (53%) in the leadership commitment domain to (72%) for AMS procedure application (actions). Based on the mean score, there was no significant difference between hospitals according to location, size, and specialty. The most neglected core elements that emerged as top priority areas were the provision of financial support, collaboration, access, as well as monitoring and evaluation., Conclusion: The current results revealed significant shortcomings in the AMS program in public hospitals despite 4 years of implementation and policy support. Most of the core elements of the AMS program were below average, which requires hospital leadership commitment, and multifaceted collaborative actions from the concerned stakeholders in Jordan., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Hassan, Dahmash, Madi, Tarawneh, Jomhawi, Alkhob, Ghanem and Halasa.)
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- 2023
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40. Upholding Quality and Patient Safety during COVID-19 Pandemic-A Jordanian Case Study.
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Dahmash EZ, Madi T, Hassan SK, Oroud Y, Shatat A, Jalabneh R, Rashideh HA, Aljayyousi A, and Iyire A
- Abstract
Background: The advent of the COVID-19 pandemic caused a rapid increase in demand for healthcare services over a prolonged period, and the hospital emergency preparedness system has been essential. Therefore, this study aimed to explore Jordanian hospitals' response to emergency situations and examine the underlying role and effect of accreditation programs as a "Quality and Patient Safety" tool to deal with emergency situations during the pandemic., Methods: An online survey for a cross-sectional study was conducted in Jordan between 1 March and 30 May 2022, to examine the opinions of hospitals' top, senior, and middle managers using a validated questionnaire., Results: A total of 200 healthcare providers from 30 hospitals participated in the study. From the areas within accreditation standards that were investigated, capacity building on emergency preparedness and communication abilities received the least scores (2.46 and 2.48, respectively). Additionally, hospitals with mature quality and patient safety culture (>3 accreditation cycles) demonstrated a statistically significant difference in score in two domains-emergency preparedness ( p = 0.027) and infection prevention and control ( p = 0.024)., Conclusions: During outbreaks, hospitals that are required to comply with accreditation standards that address all emergency preparedness aspects will fare better in quality performance.
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- 2023
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41. Assessment of Hospital Readiness to Respond to COVID-19 Pandemic in Jordan-A Cross Sectional Study.
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Dahmash EZ, Madi T, Shatat A, Oroud Y, Hassan SK, Nassar O, and Iyire A
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- Humans, Cross-Sectional Studies, Pandemics, Jordan epidemiology, Hospitals, COVID-19 epidemiology
- Abstract
During the global COVID-19 pandemic, hospitals faced tremendous pressure to cope with the emergency preparedness situations needed to cater for the influx of patients while maintaining their essential services. This study aimed to assess the level of readiness of hospitals in Jordan to respond to the COVID-19 pandemic using the WHO hospital readiness checklist. A cross-sectional survey using the modified and validated checklist was conducted in Jordan between 15 May and 15 June 2021. The checklist entailed ten key response functions with a total of 60 activities. Data from 22 hospitals were collected through a structured survey process by two surveyors for each hospital. The overall readiness score of hospitals was 1.77 ± 0.20, with a lower overall score in the northern region (1.65 ± 0.24) than the middle (1.86 ± 0.07) or southern (1.84 ± 0.14) regions. The diagnosis response function scored highest (1.95); but despite efforts, contingency plan development was not met by most hospitals, with a total score ≤ 1.45. Provision of psychological support and occupational health support to ensure the wellbeing of staff scored below average. Outcomes from this survey exposed gaps while offering a framework for upcoming endeavors to improve hospital readiness for any potential pandemic.
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- 2023
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42. Assessment of Perceived Compliance and Barriers to Personal Protective Equipment Use Among Healthcare Workers During the COVID-19 Pandemic's Second Wave Surge: "Walk to Talk" Cross-Sectional Correlational Study.
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Badran EF, Jarrah S, Masadeh R, Al Hammad A, Al Shimi R, Salhout S, Al Wahabi N, Al Jaberi M, Rayyan A, Madi T, and Hassan S
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- Humans, Middle Aged, Cross-Sectional Studies, Pandemics prevention & control, Infectious Disease Transmission, Patient-to-Professional, Personal Protective Equipment, Health Personnel, COVID-19 epidemiology
- Abstract
Objective: This study aimed at investigating HCWs' perceptions of PPE compliance and barriers, as well as influencing factors, in order to develop methods to combat the rise in their infection rates., Methods: During the 'second wave' surge, a cross-sectional correlational analysis was conducted over a 1-month period. It consists of HCWs from various hospital sectors that admit COVID-19 patients using an online self-administered predesigned tool., Results: Out of the 285 recruited participants, 36.1% had previously been diagnosed with COVID-19. Around 71% received training on PPE use. The perceived compliance was good for (PPE) usage (mean 2.60 ± 1.10). A significant higher compliance level was correlated with previous diagnosis with COVID-19, working with patients diagnosed with COVID-19, and having a direct contact with a family member older than 45 years old (P < 0.01). The main perceived barriers to the use of PPEs were unavailability of full PPEs (35%), interference with their ability to provide patient care (29%), not enough time to comply with the rigors of PPEs (23.2%) and working in emergency situations (22.5%). With regards to perceived barriers, those working with patients diagnosed with COVID-19 and those who reported having a direct contact with a family member older than 45 years old showed significantly higher level of barriers., Conclusion: A series of measures, including prioritization of PPE acquisition, training, and monitoring to guarantee appropriate resources for IPC, are necessary to reduce transmission.
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- 2021
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43. The State of Cancer Care in the United Arab Emirates in 2020: Challenges and Recommendations, A report by the United Arab Emirates Oncology Task Force.
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Al-Shamsi H, Darr H, Abu-Gheida I, Ansari J, McManus MC, Jaafar H, Tirmazy SH, Elkhoury M, Azribi F, Jelovac D, Doufan TA, Labban AR, Basha AA, Samir A, Maarraoui A, Al Dameh A, Al-Awadhi A, Al Haj Ali B, Aboud B, Elshorbagy D, Trad D, Abdul Jabbar D, Hamza D, Ashtar E, Dawoud E, Aleassa EM, Khan F, Iqbal F, Abdellatif H, Afrit M, Masri MH, Abuhaleeqa M, Alfalasi M, Omara M, Diab M, Latif MF, Oner M, Dreier N, Almarzouqi O, Singarachari RA, Bendardaf R, Alrawi S, Aldeen SS, Rana S, Talima S, Abdelgawad T, Ahluwalia A, Alkasab T, Madi T, Alkhouri T, Ul Haq U, Alabed YZ, Azzam M, Ali Z, Abbas MA, Razek AA, and Al-Khatib F
- Subjects
- History, 21st Century, Humans, United Arab Emirates, Neoplasms epidemiology
- Abstract
With cancer being the third leading cause of mortality in the United Arab Emirates (UAE), there has been significant investment from the government and private health care providers to enhance the quality of cancer care in the UAE. The UAE is a developing country with solid economic resources that can be utilized to improve cancer care across the country. There is limited data regarding the incidence, survival, and potential risk factors for cancer in the UAE. The UAE Oncology Task Force was established in 2019 by cancer care providers from across the UAE under the auspices of Emirates Oncology Society. In this paper we summarize the history of cancer care in the UAE, report the national cancer incidence, and outline current challenges and opportunities to enhance and standardize cancer care. We provide recommendations for policymakers and the UAE Oncology community for the delivery of high-quality cancer care. These recommendations are aligned with the UAE government's vision to reduce cancer mortality and provide high quality healthcare for its citizens.
- Published
- 2020
44. Data Acceptance Criteria for Standardized Human-Associated Fecal Source Identification Quantitative Real-Time PCR Methods.
- Author
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Shanks OC, Kelty CA, Oshiro R, Haugland RA, Madi T, Brooks L, Field KG, and Sivaganesan M
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- Bacteria classification, Bacteria genetics, DNA, Bacterial classification, DNA, Bacterial genetics, DNA, Bacterial isolation & purification, Environmental Monitoring methods, Feces chemistry, Humans, Real-Time Polymerase Chain Reaction standards, Reproducibility of Results, Sewage microbiology, Feces microbiology, Real-Time Polymerase Chain Reaction methods, Water Microbiology standards, Water Pollution analysis, Water Quality standards
- Abstract
There is growing interest in the application of human-associated fecal source identification quantitative real-time PCR (qPCR) technologies for water quality management. The transition from a research tool to a standardized protocol requires a high degree of confidence in data quality across laboratories. Data quality is typically determined through a series of specifications that ensure good experimental practice and the absence of bias in the results due to DNA isolation and amplification interferences. However, there is currently a lack of consensus on how best to evaluate and interpret human fecal source identification qPCR experiments. This is, in part, due to the lack of standardized protocols and information on interlaboratory variability under conditions for data acceptance. The aim of this study is to provide users and reviewers with a complete series of conditions for data acceptance derived from a multiple laboratory data set using standardized procedures. To establish these benchmarks, data from HF183/BacR287 and HumM2 human-associated qPCR methods were generated across 14 laboratories. Each laboratory followed a standardized protocol utilizing the same lot of reference DNA materials, DNA isolation kits, amplification reagents, and test samples to generate comparable data. After removal of outliers, a nested analysis of variance (ANOVA) was used to establish proficiency metrics that include lab-to-lab, replicate testing within a lab, and random error for amplification inhibition and sample processing controls. Other data acceptance measurements included extraneous DNA contamination assessments (no-template and extraction blank controls) and calibration model performance (correlation coefficient, amplification efficiency, and lower limit of quantification). To demonstrate the implementation of the proposed standardized protocols and data acceptance criteria, comparable data from two additional laboratories were reviewed. The data acceptance criteria proposed in this study should help scientists, managers, reviewers, and the public evaluate the technical quality of future findings against an established benchmark., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)
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- 2016
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45. Detection limits and cost comparisons of human- and gull-associated conventional and quantitative PCR assays in artificial and environmental waters.
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Riedel TE, Zimmer-Faust AG, Thulsiraj V, Madi T, Hanley KT, Ebentier DL, Byappanahalli M, Layton B, Raith M, Boehm AB, Griffith JF, Holden PA, Shanks OC, Weisberg SB, and Jay JA
- Subjects
- Animals, Bacteroidetes isolation & purification, Biological Assay economics, Biological Assay methods, Costs and Cost Analysis, Endpoint Determination economics, Endpoint Determination methods, Environmental Pollution analysis, Feces chemistry, Genetic Markers, Humans, Linear Models, Logistic Models, Water Microbiology standards, Water Quality standards, Charadriiformes, DNA, Bacterial isolation & purification, Limit of Detection, Polymerase Chain Reaction economics, Polymerase Chain Reaction methods, Water chemistry
- Abstract
Some molecular methods for tracking fecal pollution in environmental waters have both PCR and quantitative PCR (qPCR) assays available for use. To assist managers in deciding whether to implement newer qPCR techniques in routine monitoring programs, we compared detection limits (LODs) and costs of PCR and qPCR assays with identical targets that are relevant to beach water quality assessment. For human-associated assays targeting Bacteroidales HF183 genetic marker, qPCR LODs were 70 times lower and there was no effect of target matrix (artificial freshwater, environmental creek water, and environmental marine water) on PCR or qPCR LODs. The PCR startup and annual costs were the lowest, while the per reaction cost was 62% lower than the Taqman based qPCR and 180% higher than the SYBR based qPCR. For gull-associated assays, there was no significant difference between PCR and qPCR LODs, target matrix did not effect PCR or qPCR LODs, and PCR startup, annual, and per reaction costs were lower. Upgrading to qPCR involves greater startup and annual costs, but this increase may be justified in the case of the human-associated assays with lower detection limits and reduced cost per sample., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
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- 2014
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46. Performance of human fecal anaerobe-associated PCR-based assays in a multi-laboratory method evaluation study.
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Layton BA, Cao Y, Ebentier DL, Hanley K, Ballesté E, Brandão J, Byappanahalli M, Converse R, Farnleitner AH, Gentry-Shields J, Gidley ML, Gourmelon M, Lee CS, Lee J, Lozach S, Madi T, Meijer WG, Noble R, Peed L, Reischer GH, Rodrigues R, Rose JB, Schriewer A, Sinigalliano C, Srinivasan S, Stewart J, Van De Werfhorst LC, Wang D, Whitman R, Wuertz S, Jay J, Holden PA, Boehm AB, Shanks O, and Griffith JF
- Subjects
- Bacteria, Anaerobic genetics, Bacteria, Anaerobic isolation & purification, Bacteria, Anaerobic metabolism, California, Humans, Limit of Detection, Wastewater microbiology, Bacteria, Anaerobic classification, DNA, Bacterial analysis, Environmental Monitoring methods, Feces microbiology, Real-Time Polymerase Chain Reaction methods, Water Microbiology, Water Pollution analysis
- Abstract
A number of PCR-based methods for detecting human fecal material in environmental waters have been developed over the past decade, but these methods have rarely received independent comparative testing in large multi-laboratory studies. Here, we evaluated ten of these methods (BacH, BacHum-UCD, Bacteroides thetaiotaomicron (BtH), BsteriF1, gyrB, HF183 endpoint, HF183 SYBR, HF183 Taqman(®), HumM2, and Methanobrevibacter smithii nifH (Mnif)) using 64 blind samples prepared in one laboratory. The blind samples contained either one or two fecal sources from human, wastewater or non-human sources. The assay results were assessed for presence/absence of the human markers and also quantitatively while varying the following: 1) classification of samples that were detected but not quantifiable (DNQ) as positive or negative; 2) reference fecal sample concentration unit of measure (such as culturable indicator bacteria, wet mass, total DNA, etc); and 3) human fecal source type (stool, sewage or septage). Assay performance using presence/absence metrics was found to depend on the classification of DNQ samples. The assays that performed best quantitatively varied based on the fecal concentration unit of measure and laboratory protocol. All methods were consistently more sensitive to human stools compared to sewage or septage in both the presence/absence and quantitative analysis. Overall, HF183 Taqman(®) was found to be the most effective marker of human fecal contamination in this California-based study., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
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47. The determination of tissue-specific DNA methylation patterns in forensic biofluids using bisulfite modification and pyrosequencing.
- Author
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Madi T, Balamurugan K, Bombardi R, Duncan G, and McCord B
- Subjects
- Adult, Analysis of Variance, CpG Islands, DNA blood, DNA chemistry, DNA genetics, Epigenomics, Epithelial Cells chemistry, Female, Genetic Markers genetics, Humans, Male, Middle Aged, Organ Specificity, Polymerase Chain Reaction, Reproducibility of Results, Saliva chemistry, Spermatozoa chemistry, Sulfites, DNA analysis, DNA Methylation, Forensic Genetics methods, Sequence Analysis, DNA methods
- Abstract
The goal of this study is to explore the application of epigenetic markers in the identification of biofluids that are commonly found at the crime scene. A series of genetic loci were examined in order to define epigenetic markers that display differential methylation patterns between blood, saliva, semen, and epithelial tissue. Among the different loci tested, we have identified a panel of markers, C20orf117, ZC3H12D, BCAS4, and FGF7, that can be used in the determination of these four tissue types. Since methylation modifications occur at cytosine bases that are immediately followed by guanine bases (CpG sites), methylation levels were measured at CpG sites spanning each marker. Up to 11 samples of each tissue type were collected and subjected to bisulfite modification to convert unmethylated CpG-associated cytosine bases to thymine bases. The bisulfite modified DNA was then amplified via nested PCR using a primer set of which one primer was biotin labeled. Biotinylated PCR products were in turn analyzed and the methylation level at each CpG site was quantitated by pyrosequencing. The percent methylation values at each CpG site were determined and averaged for each tissue type. The results indicated significant methylation differences between the tissue types. The methylation patterns at the ZC3H12D and FGF7 loci differentiated sperm from blood, saliva, and epithelial cells. The C20orf117 locus differentiated blood from sperm, saliva, and epithelial cells and saliva was differentiated from blood, sperm, and epithelial cells at a fourth locus, BCAS4. The results of this study demonstrate the applicability of epigenetic markers as a novel tool for the determination of biofluids using bisulfite modification and pyrosequencing., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2012
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48. Online in situ x-ray diffraction setup for structural modification studies during swift heavy ion irradiation.
- Author
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Grygiel C, Lebius H, Bouffard S, Quentin A, Ramillon JM, Madi T, Guillous S, Been T, Guinement P, Lelièvre D, and Monnet I
- Abstract
The high energy density of electronic excitations due to the impact of swift heavy ions can induce structural modifications in materials. We present an x-ray diffractometer called ALIX ("Analyse en Ligne sur IRRSUD par diffraction de rayons X"), which has been set up at the low-energy beamline (IRRadiation SUD - IRRSUD) of the Grand Accélérateur National d'Ions Lourds facility, to allow the study of structural modification kinetics as a function of the ion fluence. The x-ray setup has been modified and optimized to enable irradiation by swift heavy ions simultaneously to x-ray pattern recording. We present the capability of ALIX to perform simultaneous irradiation-diffraction by using energy discrimination between x-rays from diffraction and from ion-target interaction. To illustrate its potential, results of sequential or simultaneous irradiation-diffraction are presented in this article to show radiation effects on the structural properties of ceramics. Phase transition kinetics have been studied during xenon ion irradiation of polycrystalline MgO and SrTiO(3). We have observed that MgO oxide is radiation-resistant to high electronic excitations, contrary to the high sensitivity of SrTiO(3), which exhibits transition from the crystalline to the amorphous state during irradiation. By interpreting the amorphization kinetics of SrTiO(3), defect overlapping models are discussed as well as latent track characteristics. Together with a transmission electron microscopy study, we conclude that a single impact model describes the phase transition mechanism.
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- 2012
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49. Safety and efficacy of the RTS,S/AS01E candidate malaria vaccine given with expanded-programme-on-immunisation vaccines: 19 month follow-up of a randomised, open-label, phase 2 trial.
- Author
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Asante KP, Abdulla S, Agnandji S, Lyimo J, Vekemans J, Soulanoudjingar S, Owusu R, Shomari M, Leach A, Jongert E, Salim N, Fernandes JF, Dosoo D, Chikawe M, Issifou S, Osei-Kwakye K, Lievens M, Paricek M, Möller T, Apanga S, Mwangoka G, Dubois MC, Madi T, Kwara E, Minja R, Hounkpatin AB, Boahen O, Kayan K, Adjei G, Chandramohan D, Carter T, Vansadia P, Sillman M, Savarese B, Loucq C, Lapierre D, Greenwood B, Cohen J, Kremsner P, Owusu-Agyei S, Tanner M, and Lell B
- Subjects
- Diphtheria-Tetanus-Pertussis Vaccine administration & dosage, Female, Follow-Up Studies, Gabon epidemiology, Ghana epidemiology, Haemophilus Vaccines administration & dosage, Hepatitis B Vaccines administration & dosage, Humans, Immunization Programs, Immunization Schedule, Infant, Malaria Vaccines administration & dosage, Malaria, Falciparum diagnosis, Malaria, Falciparum epidemiology, Male, Poliovirus Vaccine, Oral administration & dosage, Program Evaluation, Severity of Illness Index, Tanzania epidemiology, Time Factors, Treatment Outcome, Antibodies, Protozoan blood, Malaria Vaccines adverse effects, Malaria Vaccines immunology, Malaria, Falciparum immunology, Malaria, Falciparum prevention & control, Protozoan Proteins immunology
- Abstract
Background: The RTS,S/AS01(E) candidate malaria vaccine is being developed for immunisation of infants in Africa through the expanded programme on immunisation (EPI). 8 month follow-up data have been reported for safety and immunogenicity of RTS,S/AS01(E) when integrated into the EPI. We report extended follow-up to 19 months, including efficacy results., Methods: We did a randomised, open-label, phase 2 trial of safety and efficacy of the RTS,S/AS01(E) candidate malaria vaccine given with EPI vaccines between April 30, 2007, and Oct 7, 2009, in Ghana, Tanzania, and Gabon. Eligible children were 6-10 weeks of age at first vaccination, without serious acute or chronic illness. All children received the EPI diphtheria, tetanus, pertussis (inactivated whole-cell), and hepatitis-B vaccines, Haemophilus influenzae type b vaccine, and oral polio vaccine at study months 0, 1, and 2, and measles vaccine and yellow fever vaccines at study month 7. Participants were randomly assigned (1:1:1) to receive three doses of RTS,S/AS01(E) at 6, 10, and 14 weeks (0, 1, 2 month schedule) or at 6 weeks, 10 weeks, and 9 months (0, 2, 7 month schedule) or placebo. Randomisation was according to a predefined block list with a computer-generated randomisation code. Detection of serious adverse events and malaria was by passive case detection. Antibodies against Plasmodium falciparum circumsporozoite protein and HBsAg were monitored for 19 months. This study is registered with ClinicalTrials.gov, number NCT00436007., Findings: 511 children were enrolled. Serious adverse events occurred in 57 participants in the RTS,S/AS01(E) 0, 1, 2 month group (34%, 95% CI 27-41), 47 in the 0, 1, 7 month group (28%, 21-35), and 49 (29%, 22-36) in the control group; none were judged to be related to study vaccination. At month 19, anticircumsporozoite immune responses were significantly higher in the RTS,S/AS01(E) groups than in the control group. Vaccine efficacy for the 0, 1, 2 month schedule (2 weeks after dose three to month 19, site-adjusted according-to-protocol analysis) was 53% (95% CI 26-70; p=0·0012) against first malaria episodes and 59% (36-74; p=0·0001) against all malaria episodes. For the entire study period, (total vaccinated cohort) vaccine efficacy against all malaria episodes was higher with the 0, 1, 2 month schedule (57%, 95% CI 33-73; p=0·0002) than with the 0, 1, 7 month schedule (32% CI 16-45; p=0·0003). 1 year after dose three, vaccine efficacy against first malaria episodes was similar for both schedules (0, 1, 2 month group, 61·6% [95% CI 35·6-77·1], p<0·001; 0, 1, 7 month group, 63·8% [40·4-78·0], p<0·001, according-to-protocol cohort)., Interpretation: Vaccine efficacy was consistent with the target put forward by the WHO-sponsored malaria vaccine technology roadmap for a first-generation malaria vaccine. The 0, 1, 2 month vaccine schedule has been selected for phase 3 candidate vaccine assessment., Funding: Program for Appropriate Technology in Health Malaria Vaccine Initiative; GlaxoSmithKline Biologicals., (Copyright © 2011 Elsevier Ltd. All rights reserved.)
- Published
- 2011
- Full Text
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