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https://www.readbyqxmd.com/read/29333672/controlled-pattern-imputation-for-sensitivity-analysis-of-longitudinal-binary-and-ordinal-outcomes-with-nonignorable-dropout
#1
Yongqiang Tang
The controlled imputation method refers to a class of pattern mixture models that have been commonly used as sensitivity analyses of longitudinal clinical trials with nonignorable dropout in recent years. These pattern mixture models assume that participants in the experimental arm after dropout have similar response profiles to the control participants or have worse outcomes than otherwise similar participants who remain on the experimental treatment. In spite of its popularity, the controlled imputation has not been formally developed for longitudinal binary and ordinal outcomes partially due to the lack of a natural multivariate distribution for such endpoints...
January 15, 2018: Statistics in Medicine
https://www.readbyqxmd.com/read/29301546/spatial-and-temporal-patterns-of-dengue-infections-in-timor-leste-2005-2013
#2
Kinley Wangdi, Archie C A Clements, Tai Du, Susana Vaz Nery
BACKGROUND: Dengue remains an important public health problem in Timor-Leste, with several major epidemics occurring over the last 10 years. The aim of this study was to identify dengue clusters at high geographical resolution and to determine the association between local environmental characteristics and the distribution and transmission of the disease. METHODS: Notifications of dengue cases that occurred from January 2005 to December 2013 were obtained from the Ministry of Health, Timor-Leste...
January 4, 2018: Parasites & Vectors
https://www.readbyqxmd.com/read/29299492/economic-analysis-of-bisphosphonate-use-after-distal-radius-fracture-for-prevention-of-hip-fracture
#3
Suneel B Bhat, Asif M Ilyas
Background: Osteoporosis is a common condition among the elderly population, and is associated with an increased risk of fracture. One of the most common fragility fractures involve the distal radius, and are associated with risk of subsequent fragility fracture. Early treatment with bisphosphonates has been suggested to decrease the population hip fracture burden. However, there have been no prior economic evaluations of the routine treatment of distal radius fracture patients with bisphosphonates, or the implications on hip fracture rate reduction...
November 2017: Archives of Bone and Joint Surgery
https://www.readbyqxmd.com/read/29298736/multiple-frequency-bioimpedance-devices-for-fluid-management-in-people-with-chronic-kidney-disease-receiving-dialysis-a-systematic-review-and-economic-evaluation
#4
Graham Scotland, Moira Cruickshank, Elisabet Jacobsen, David Cooper, Cynthia Fraser, Michal Shimonovich, Angharad Marks, Miriam Brazzelli
BACKGROUND: Chronic kidney disease (CKD) is a long-term condition requiring treatment such as conservative management, kidney transplantation or dialysis. To optimise the volume of fluid removed during dialysis (to avoid underhydration or overhydration), people are assigned a 'target weight', which is commonly assessed using clinical methods, such as weight gain between dialysis sessions, pre- and post-dialysis blood pressure and patient-reported symptoms. However, these methods are not precise, and measurement devices based on bioimpedance technology are increasingly used in dialysis centres...
January 2018: Health Technology Assessment: HTA
https://www.readbyqxmd.com/read/29286942/novel-approach-for-automating-medical-emergency-protocol-in-military-environment
#5
Ivica Kocev, Jugoslav Achkoski, Dimitar Bogatinov, Saso Koceski, Vladimir Trajkovik, Goce Stevanoski, Boban Temelkovski
BACKGROUND AND OBJECTIVES: Categorization of the casualties in accordance with medical care priorities is crucial in a military environment. Automation of the triage process is still a challenging task. The goal of the paper is to propose a novel algorithm for automation of medical emergency protocol in the military environment by the creation of classifiers that can provide accurate prioritization of injured soldier cases. It is a part of a complex military telemedicine system that provides continuous monitoring of soldiers' vital data gathered on-site using an unobtrusive set of sensors...
December 22, 2017: Technology and Health Care: Official Journal of the European Society for Engineering and Medicine
https://www.readbyqxmd.com/read/29286756/irreversible-local-markov-chains-with-rapid-convergence-towards-equilibrium
#6
Sebastian C Kapfer, Werner Krauth
We study the continuous one-dimensional hard-sphere model and present irreversible local Markov chains that mix on faster time scales than the reversible heat bath or Metropolis algorithms. The mixing time scales appear to fall into two distinct universality classes, both faster than for reversible local Markov chains. The event-chain algorithm, the infinitesimal limit of one of these Markov chains, belongs to the class presenting the fastest decay. For the lattice-gas limit of the hard-sphere model, reversible local Markov chains correspond to the symmetric simple exclusion process (SEP) with periodic boundary conditions...
December 15, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29281984/the-alarming-problems-of-confounding-equivalence-using-logistic-regression-models-in-the-perspective-of-causal-diagrams
#7
Yuanyuan Yu, Hongkai Li, Xiaoru Sun, Ping Su, Tingting Wang, Yi Liu, Zhongshang Yuan, Yanxun Liu, Fuzhong Xue
BACKGROUND: Confounders can produce spurious associations between exposure and outcome in observational studies. For majority of epidemiologists, adjusting for confounders using logistic regression model is their habitual method, though it has some problems in accuracy and precision. It is, therefore, important to highlight the problems of logistic regression and search the alternative method. METHODS: Four causal diagram models were defined to summarize confounding equivalence...
December 28, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/29281501/estimation-of-cadmium-uptake-by-tobacco-plants-from-laboratory-leaching-tests
#8
Jelena P Marković, Mihajlo D Jović, Ivana D Smičiklas, Marija Z Šljivić-Ivanović, Slavko N Smiljanić, Antonije E Onjia, Aleksandar R Popović
The objective of the present study was to determine the impact of cadmium (Cd) concentration in the soil on its uptake by tobacco plants, and to compare the ability of diverse extraction procedures for determining Cd bioavailability and predicting soil-to-plant transfer and Cd plant concentrations. The pseudo-total digestion procedure, modified Tessier sequential extraction and six standard single-extraction tests for estimation of metal mobility and bioavailability were used for the leaching of Cd from a native soil, as well as samples artificially contaminated over a wide range of Cd concentrations...
December 27, 2017: Journal of Environmental Science and Health. Part A, Toxic/hazardous Substances & Environmental Engineering
https://www.readbyqxmd.com/read/29277330/a-hidden-semi-markov-model-based-approach-for-rehabilitation-exercise-assessment
#9
Marianna Capecci, Maria Gabriella Ceravolo, Francesco Ferracuti, Sabrina Iarlori, Ville Kyrki, Andrea Monteriù, Luca Romeo, Federica Verdini
In this paper, a Hidden Semi-Markov Model (HSMM) based approach is proposed to evaluate and monitor body motion during a rehabilitation training program. The approach extracts clinically relevant motion features from skeleton joint trajectories, acquired by the RGB-D camera, and provides a score for the subject's performance. The approach combines different aspects of rule and template based methods. The features have been defined by clinicians as exercise descriptors and are then assessed by a HSMM, trained upon an exemplar motion sequence...
December 22, 2017: Journal of Biomedical Informatics
https://www.readbyqxmd.com/read/29276799/optimization-of-an-adaptive-spect-system-with-the-scanning-linear-estimator
#10
Nasrin Ghanbari, Eric Clarkson, Matthew Kupinski, Xin Li
A method for optimization of an adaptive Single Photon Emission Computed Tomography (SPECT) system is presented. Adaptive imaging systems can quickly change their hardware configuration in response to data being generated in order to improve image quality for a specific task. In this work we simulate an adaptive SPECT system and propose a method for finding the adaptation that maximizes the performance on a signal estimation task. To start with, a simulated object model containing a spherical signal is imaged with a scout configuration...
September 2017: IEEE Transactions on Radiation and Plasma Medical Sciences
https://www.readbyqxmd.com/read/29250805/innovative-modeling-of-naturalistic-driving-data-inference-and-prediction
#11
Paul S Albert
Naturalistic driving studies provide opportunities for investigating the effects of key driving exposures on risky driving performance and accidents. New technology provides a realistic assessment of risky driving through the intensive monitoring of kinematic behavior while driving. These studies with their complex data structures provide opportunities for statisticians to develop needed modeling techniques for statistical inference. This article discusses new statistical modeling procedures that were developed to specifically answer important analytical questions for naturalistic driving studies...
December 18, 2017: Statistics in Medicine
https://www.readbyqxmd.com/read/29229523/inference-in-population-genetics-using-forward-and-backward-discrete-and-continuous-time-processes
#12
Juraj Bergman, Dominik Schrempf, Carolin Kosiol, Claus Vogl
A central aim of population genetics is the inference of the evolutionary history of a population. To this end, the underlying process can be represented by a model of the evolution of allele frequencies parametrized by e.g., the population size, mutation rates and selection coefficients. A large class of models use forward-in-time models, such as the discrete Wright-Fisher and Moran models and the continuous forward diffusion, to obtain distributions of population allele frequencies, conditional on an ancestral initial allele frequency distribution...
December 8, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/29222509/impact-of-model-calibration-on-cost-effectiveness-analysis-of-cervical-cancer-prevention
#13
David Moriña, Silvia de Sanjosé, Mireia Diaz
Markov chain models are commonly used to simulate the natural history of human papillomavirus infection and subsequent cervical lesions with the aim of predicting future benefits of health interventions. Developing and calibrating these models entails making a number of critical decisions that will influence the ability of the model to reflect real conditions and predict future situations. Accuracy of selected inputs and calibration procedures are two of the crucial aspects for model performance and understanding their influence is essential, especially when involves policy decisions...
December 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29191177/performance-comparison-of-first-order-conditional-estimation-with-interaction-and-bayesian-estimation-methods-for-estimating-the-population-parameters-and-its-distribution-from-data-sets-with-a-low-number-of-subjects
#14
Sudeep Pradhan, Byungjeong Song, Jaeyeon Lee, Jung-Woo Chae, Kyung Im Kim, Hyun-Moon Back, Nayoung Han, Kwang-Il Kwon, Hwi-Yeol Yun
BACKGROUND: Exploratory preclinical, as well as clinical trials, may involve a small number of patients, making it difficult to calculate and analyze the pharmacokinetic (PK) parameters, especially if the PK parameters show very high inter-individual variability (IIV). In this study, the performance of a classical first-order conditional estimation with interaction (FOCE-I) and expectation maximization (EM)-based Markov chain Monte Carlo Bayesian (BAYES) estimation methods were compared for estimating the population parameters and its distribution from data sets having a low number of subjects...
December 1, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/29165789/medicaid-cost-savings-of-a-preventive-home-visit-program-for-disabled-older-adults
#15
Sarah L Szanton, Y Natalia Alfonso, Bruce Leff, Jack Guralnik, Jennifer L Wolff, Ian Stockwell, Laura N Gitlin, David Bishai
BACKGROUND/OBJECTIVES: Little is known about cost savings of programs that reduce disability in older adults. The objective was to determine whether the Community Aging in Place, Advancing Better Living for Elders (CAPABLE) program saves Medicaid more money than it costs to provide. DESIGN: Single-arm clinical trial (N = 204) with a comparison group of individuals (N = 2,013) dually eligible for Medicaid and Medicare matched on baseline geographic and demographic characteristics, chronic conditions, and healthcare use...
November 22, 2017: Journal of the American Geriatrics Society
https://www.readbyqxmd.com/read/29162508/targeted-delivery-of-nucleic-acids-into-xenograft-tumors-mediated-by-novel-folate-equipped-liposomes
#16
Tatyana O Kabilova, Elena V Shmendel, Daniil V Gladkikh, Elena L Chernolovskaya, Oleg V Markov, Nina G Morozova, Mikhail A Maslov, Marina A Zenkova
Folate receptors (FR) are cellular markers highly expressed in various cancer cells. Here, we report on the synthesis of a novel folate-containing lipoconjugate (FC) built of 1,2-di-O-ditetradecyl-rac-glycerol and folic acid connected via a PEG spacer, and the evaluation of the FC as a targeting component of liposomal formulations for nucleic acid (NA) delivery into FR expressing tumor cells. FR-targeting liposomes, based on polycationic lipid 1,26-bis(cholest-5-en-3β-yloxycarbonylamino)-7,11,16,20-tetraazahexacosan tetrahydrochloride (2X3), lipid helper dioleoylphosphatidylethanolamine (DOPE) and novel FC, formed small compact particles in solution with diameters of 60 ± 22 nm, and were not toxic to cells...
November 18, 2017: European Journal of Pharmaceutics and Biopharmaceutics
https://www.readbyqxmd.com/read/29162004/sequence-classification-using-third-order-moments
#17
Rasmus Troelsgaard, Lars Kai Hansen
Model-based classification of sequence data using a set of hidden Markov models is a well-known technique. The involved score function, which is often based on the class-conditional likelihood, can, however, be computationally demanding, especially for long data sequences. Inspired by recent theoretical advances in spectral learning of hidden Markov models, we propose a score function based on third-order moments. In particular, we propose to use the Kullback-Leibler divergence between theoretical and empirical third-order moments for classification of sequence data with discrete observations...
November 21, 2017: Neural Computation
https://www.readbyqxmd.com/read/29161872/asymptotic-behavior-of-a-delayed-stochastic-logistic-model-with-impulsive-perturbations
#18
Sanling Yuan, Xuehui Ji, Huaiping Zhu
In this paper, we investigate the dynamics of a delayed logistic model with both impulsive and stochastic perturbations. The impulse is introduced at fixed moments and the stochastic perturbation is of white noise type which is assumed to be proportional to the population density. We start with the existence and uniqueness of the positive solution of the model, then establish sufficient conditions ensuring its global attractivity. By using the theory of integral Markov semigroups, we further derive sufficient conditions for the existence of the stationary distribution of the system...
October 2017: Mathematical Biosciences and Engineering: MBE
https://www.readbyqxmd.com/read/29152789/automatic-differential-analysis-of-nmr-experiments-in-complex-samples
#19
Laure Margueritte, Petar Markov, Lionel Chiron, Jean-Philippe Starck, Catherine Vonthron-Sã nà Cheau, Mã Lanie Bourjot, Marc-Andrà Delsuc
Liquid state NMR is a powerful tool for the analysis of complex mixtures of unknown molecules. This capacity has been used in many analytical approaches: metabolomics, identification of active compounds in natural extracts, characterization of species, and such studies require the acquisition of many diverse NMR measurements on series of samples. While acquisition can easily be performed automatically, the number of NMR experiments involved in these studies increases very rapidly and this data avalanche requires to resort to automatic processing and analysis...
November 20, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29150794/shunt-surgery-in-idiopathic-normal-pressure-hydrocephalus-is-cost-effective-a-cost-utility-analysis
#20
Mats Tullberg, Josefine Persson, Jakob Petersen, Per Hellström, Carsten Wikkelsø, Åsa Lundgren-Nilsson
BACKGROUND: The objective was to evaluate the cost-effectiveness of shunt surgery in patients with idiopathic normal pressure hydrocephalus (iNPH). METHODS: Health-related quality of life was evaluated before and 6 months after surgery using the EQ-5D-3 L (EuroQOL group five-dimensions health survey) in 30 patients (median age, 71 years; range, 65-89 years) diagnosed with iNPH. The costs associated with shunt surgery were assessed by a detailed survey with interviews and extraction of register data concerning the cost of hospital care, primary care, residential care, home-care service and informal care...
November 17, 2017: Acta Neurochirurgica
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