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Log normal distribution

Anli Gao, Perry Martos
Background: Estimation of measurement uncertainty (MU) has been extensively addressed in documents from standard authorities. In microbiology, bacterial counts are log transformed to get a more normal distribution. Unfortunately, the difference between using original and log-transformed data appears to not have been investigated even in publications focusing on MU estimation. Method: Statistical formulae inferencing and estimation of MU using real bacterial enumeration datasets. Results: Both mean and SD calculated from original data carry the same scale and unit as the original data...
August 10, 2018: Journal of AOAC International
Jiao Huo, Yunjie Liu, Yiping You, Zhu Zeng, Xuejiao Zhu, Jinyao Chen, Lishi Zhang
OBJECTIVE: To make recommendations on the design and analysis of Piga gene mutation assay on the basis of the historical control data. METHODS: All negative historical control data( total: 128) were collected to create the historical control data base, and descriptive statistics was used to determine the distribution of the data. The power of the number of animals per group, number of measured cells per animal and number of groups were discussed through simulation test based on historical data base...
July 2018: Wei Sheng Yan Jiu, Journal of Hygiene Research
Todd R Sponholtz, Ramachandran S Vasan
Few studies of the health impact of the built environment have examined downstream outcomes, such as cardiovascular disease. We analyzed the neighborhood-level proportional variance in the 10- and 30-year Framingham risk scores (FRS) in the Framingham Heart Study. Our analysis included 3,103 Offspring- and Generation 3 cohort participants 20-74 years old, inhabiting private residences in Massachusetts geocoded to neighborhoods (defined as 2000 US Census block groups) containing the residences of ≥5 participants...
2018: PloS One
Roman M Link, Bernhard Schuldt, Brendan Choat, Steven Jansen, Alexander R Cobb
Vessel length is an important functional trait for plant hydraulics, because it determines the ratio of flow resistances posed by lumen and pit membranes and hence controls xylem hydraulic efficiency. The most commonly applied methods to estimate vessel lengths are based on the injection of silicon or paint into cut-off stem segments. The number of stained vessels in a series of cross-sections in increasing distance from the injection point is then counted. The resulting infusion profiles are used to estimate the vessel length distribution using one of several statistical algorithms...
July 28, 2018: Journal of Theoretical Biology
Enida Gjoni, Friedemann Zenke, Brice Bouhours, Ralf Schneggenburger
KEY POINTS: During the computation of sound localization, neurons of the Lateral Superior Olive (LSO) integrate synaptic excitation arising from the ipsilateral ear with inhibition from the contralateral ear. We characterized the functional connectivity of the inhibitory and excitatory inputs onto LSO neurons in terms of unitary synaptic strength and convergence. Unitary inhibitory postsynaptic currents (IPSCs) can generate large conductances but their strength varies over a 10- fold range in a given recording...
July 27, 2018: Journal of Physiology
Zheng Wang, Minglong Chen, Liwen Zhang, Kan Wang, Xubiao Yu, Zhongming Zheng, Rongyue Zheng
Recently, with the accumulation of evidence that microplastic can be ingested by a variety of marine organisms, microplastic sorption behaviors towards organic contaminants (OCs) have become the subject of more studies due to the concerns about the contaminant vector effect. In this study, the priority microplastics identified in a mariculture farm in Xiangshan Bay, China, including polyethylene (PE) and nylon fibers (i.e., derived from new fishing ropes and nets), were examined for their sorption behaviors...
July 1, 2018: Science of the Total Environment
Ichiro Higashikubo, Heihachiro Arito, Yoko Eitaki, Akihiro Araki, Kenji Ando, Hidesuke Shimizu, Haruhiko Sakurai
This study quantitatively assessed personal exposure of 86 workers to indium compounds as total dust at 11 Japanese indium plants. The personal exposures to indium concentrations in the breathing zone during an 8 hr work-shift were determined by ICP-MS. The arithmetic mean indium concentration of all the workers was 0.098 mg Indium (In)/m3 , with individual values ranging from 0.0001 to 1.421 mg In/m3 . There were 11 workers whose exposure to indium concentrations exceeded the American Conference of Governmental Industrial Hygienists' Threshold Limit Value-Time Weighted Average (TLV-TWA) of 0...
July 21, 2018: Industrial Health
Jin H Yoon, Matthew T Weaver, Richard De La Garza, Robert Suchting, Chandra S Nerumalla, Yasmine Omar, Gregory S Brown, Ilana Haliwa, Thomas F Newton
BACKGROUND AND OBJECTIVES: Delay discounting is associated with numerous clinically significant aspects of substance use disorders (SUDs). Recent studies have demonstrated that different models for assessing discounting may result in disparate conclusions. The current study compared two discounting tasks: money now versus money later (M-M) and methamphetamine now versus money later (MA-M) among non-treatment seeking individuals (N = 59) with methamphetamine use disorder (MAUD). Results from each task were assessed using three different models for assessing delay discounting...
July 19, 2018: American Journal on Addictions
Dane R Van Domelen, Emily M Mitchell, Neil J Perkins, Enrique F Schisterman, Amita K Manatunga, Yijian Huang, Robert H Lyles
In a multivariable logistic regression setting where measuring a continuous exposure requires an expensive assay, a design in which the biomarker is measured in pooled samples from multiple subjects can be very cost effective. A logistic regression model for poolwise data is available, but validity requires that the assay yields the precise mean exposure for members of each pool. To account for errors, we assume the assay returns the true mean exposure plus a measurement error (ME) and/or a processing error (PE)...
July 18, 2018: Statistics in Medicine
Bernat Corominas-Murtra, Rudolf Hanel, Leonardo Zavojanni, Stefan Thurner
Sample space reducing (SSR) processes offer a simple analytical way to understand the origin and ubiquity of power-laws in many path-dependent complex systems. SRR processes show a wide range of applications that range from fragmentation processes, language formation to search and cascading processes. Here we argue that they also offer a natural framework to understand stationary distributions of generic driven non-equilibrium systems that are composed of a driving- and a relaxing process. We show that the statistics of driven non-equilibrium systems can be derived from the understanding of the nature of the underlying driving process...
July 18, 2018: Scientific Reports
Aldo Clerico, Tommaso Trenti, Rosalia Aloe, Ruggero Dittadi, Sara Rizzardi, Marco Migliardi, Roberta Musa, Mariella Dipalo, Concetta Prontera, Silvia Masotti, Veronica Musetti, Renato Tozzoli, Andrea Padoan, Marcello Bagnasco
Background The aims of this study were: (1) to calculate reliable thyroid stimulating hormone (TSH) reference intervals using laboratory databases; (2) to evaluate the relationship between TSH, sex and age values in different large Italian populations. Methods The TSH values stored in the laboratory information system of clinical laboratories of four Italian city hospitals, including 146,801 TSH measurements (with the respective age and sex data of individuals) were taken in consideration. Assuming a log-normal distribution, to log-transformed TSH values were applied the Dixon's iterative principle in order to exclude the outliers...
July 17, 2018: Clinical Chemistry and Laboratory Medicine: CCLM
Patrick Schober, Thomas R Vetter
Survival analysis, or more generally, time-to-event analysis, refers to a set of methods for analyzing the length of time until the occurrence of a well-defined end point of interest. A unique feature of survival data is that typically not all patients experience the event (eg, death) by the end of the observation period, so the actual survival times for some patients are unknown. This phenomenon, referred to as censoring, must be accounted for in the analysis to allow for valid inferences. Moreover, survival times are usually skewed, limiting the usefulness of analysis methods that assume a normal data distribution...
July 13, 2018: Anesthesia and Analgesia
John Punnose, Rajeev Kumar Malhotra, Komal Sukhija, Anu Mathew, Asha Sharma, Naimaa Choudhary
Aims: Presence of bimodality in plasma glucose distribution (BPG) and its relevance for gestational diabetes mellitus (GDM) diagnosis were studied in Asian Indian pregnant women. Methods: Fasting (FPG) and two hour plasma glucose (2-h PG) values of oral glucose tolerance tests performed in 36,530 pregnant women for GDM screening (2006-16 period), were analyzed for BPG. A unimodal normal and a mixture of two normal distributions were fitted to log-transformed FPG and 2-h PG data...
September 2018: Journal of Clinical & Translational Endocrinology
Chi Chung Alan Fung, Tomoki Fukai
The membrane potentials of cortical neurons in vivo exhibit spontaneous fluctuations between a depolarized UP state and a resting DOWN state during the slow-wave sleeps or in the resting states. This oscillatory activity is believed to engage in memory consolidation although the underlying mechanisms remain unknown. Recently, it has been shown that UP-DOWN state transitions exhibit significantly different temporal profiles in different cortical regions, presumably reflecting differences in the underlying network structure...
July 16, 2018: Scientific Reports
Daniel F Moraga-Espinoza, Eli Eshaghian, Albert Shaver, Hugh D C Smyth
Although high-speed laser imaging is the current standard to characterize the plume angle of suspension-based pressurized metered dose inhalers (pMDIs), this method is limited by the inability to identify the drug content in a droplet and simulate inhalation flow. The Plume Induction Port Evaluator (PIPE) is a modified induction port for cascade impactors that allows for the calculation of the angle of a plume based on direct drug mass quantification rather than indirect droplet illumination under airflow conditions...
July 12, 2018: AAPS Journal
Jesse Fest, Rikje Ruiter, M Arfan Ikram, Trudy Voortman, Casper H J van Eijck, Bruno H Stricker
Novel prognostic inflammatory markers of cancer survival and cardiovascular disease are; the neutrophil-to-lymphocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR) and the systemic immune-inflammation index (SII). As normal values for these markers are unknown, our objective was to obtain reference values in the general population. We obtained data from a population-based prospective cohort study of individuals aged 45 years and over between 2002 and 2014. Absolute blood counts were used to calculate the NLR, PLR and SII...
July 12, 2018: Scientific Reports
Gabriel Leitner, David Zilberman, Eduard Papirov, Sela Shefy
Clinical and subclinical mastitis affects 30% of cows and is regarded as the most significant economic burden on the dairy farm reducing milk yield and quality and increasing culling rate. A proprietary Acoustic Pulse Therapy (APT) device was developed specifically for treating dairy cows. The APT device was designed to produce deep penetrating acoustic pulses that are distributed over a large treated area at a therapeutic level. This paper presents findings from a clinical assessment of this technology for the treatment of dairy cows with subclinical and clinical mastitis...
2018: PloS One
Antony R Denman, Robin G M Crockett, Christopher J Groves-Kirkby
Radon, a naturally occurring radioactive gas generated underground by radioactive decay of nuclides contained in certain types of rocks, can concentrate inside buildings, where it poses the second-largest risk factor for lung cancer, after smoking. The highest concentrations of domestic radon in the UK occur in the south-western counties of Devon and Cornwall, but certain areas in Northamptonshire and surrounding counties in the English Midlands also have high levels. It has been shown that it is possible both to reduce the radon concentrations in existing houses and to build new homes with appropriate protection...
June 29, 2018: Journal of Environmental Radioactivity
Ning Wang, Qing-Wei Liu, Yin Zhi, Liu Cheng, Bing-Juan Ma, Yu-Xiang Mao
In order to determine the occurrence of mercury (Hg) in the dewatered sewage sludge (SS) from municipal wastewater treatment plants (MWTPs) in China, 315 SS samples were collected from 40 MWTPs. The total Hg (THg) contents of the sludge samples were analyzed using a DMA-80 Hg analyzer. It was found that THg in the samples ranged from 0.45-15.42 mg ·kg-1 . The THg data followed a log-normal distribution with a geometric mean of (2.19±3.16) mg ·kg-1 . THg contents in all the sludge samples meet the criteria set for disposal (by co-landfilling) of MWTPs sludge (GB/T 23485-2009)...
May 8, 2018: Huan Jing Ke Xue= Huanjing Kexue
Bo Zhang, Wei Liu, Ning Zhang, Arlene S Ash, Jeroan J Allison
Marginalized two-part random-effects generalized Gamma models have been proposed for analyzing medical expenditure panel data with excessive zeros. While these models provide marginal inference on expected healthcare expenditures, the usual unilateral specification of heteroscedastic variance on one of the two shape parameters for the generalized Gamma distribution in these models fails to encompass important special cases within the generalized gamma modeling framework. In this article, we construct marginalized two-part random-effects models that employ the log-normal, log-skew-normal, generalized Gamma, Weibull, Gamma, and inverse Gamma distributions to delineate the spectrum of nonzero healthcare expenditures in the second part of the models...
January 1, 2018: Statistical Methods in Medical Research
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