A Statistical Framework for Mediation in Environmental Epigenetics

2016 ◽  
Author(s):  
Duncan C. Thomas
Keyword(s):  
Experimental Data ◽  
Air Pollution ◽  
Respiratory Disease ◽  
Biological Effects ◽  
Simulated Data ◽  
Genetic Influences ◽  
Statistical Framework ◽  
General Statistical ◽  
The Individual

The biological effects of genes depend upon how they are expressed in target tissues at various points in time, which is determined by their epigenetic state and in turn may be influenced by the environment.Some experimental data suggests that such influences can be transmitted across generations.In this chapter, I propose a general statistical framework for modelling how environmental and germline genetic influences on disease is mediated by epigenetics, both within the individual and across generations.The approach is illustrated on simulated data and on a study of the effect of air pollution and the ARG/NOS family of genes on childhood respiratory disease.

Uncertainty of a Least Squares Curve Fit through Points with Known Uncertainties

1995 ◽  
Vol 23 (4) ◽  
pp. 315-326
Author(s):  
Ronald D. Flack
Keyword(s):  
Experimental Data ◽  
Least Squares ◽  
Fourth Order ◽  
Simulated Data ◽  
Higher Order ◽  
Individual Data ◽  
Linear Quadratic ◽  
Curve Fit ◽  
Data Points ◽  
The Individual

Uncertainties in least squares curve fits to data with uncertainties are examined. First, experimental data with nominal curve shapes, representing property profiles between boundaries, are simulated by adding known uncertainties to individual points. Next, curve fits to the simulated data are achieved and compared to the nominal curves. By using a large number of different sets of data, statistical differences between the two curves are quantified and, thus, the uncertainty of the curve fit is derived. Studies for linear, quadratic, and higher-order nominal curves with curve fits up to fourth order are presented herein. Typically, curve fits have uncertainties that are 50% or less than those of the individual data points. These uncertainties increase with increasing order of the least squares curve fit. The uncertainties decrease with increasing number of data points on the curves.

Study of potential curves by UHF type methods. CH4 molecule and its dissociation products

1986 ◽  
Vol 51 (4) ◽  
pp. 731-737
Author(s):  
Viliam Klimo ◽  
Jozef Tiňo
Keyword(s):  
Experimental Data ◽  
Quantum Chemistry ◽  
High Energy ◽  
Basis Set ◽  
Electronic Correlation ◽  
Exact Methods ◽  
Energy Parameters ◽  
Bond Functions ◽  
The Individual ◽  
Potential Curves

Geometry and energy parameters of the individual dissociation intermediate steps of CH4 molecule, parameters of the barrier to linearity and singlet-triplet separation of the CH2 molecule have been calculated by means of the UMP method in the minimum basis set augmented with the bond functions. The results agree well with experimental data except for the geometry of CH2(1A1) and relatively high energy values of CH(2II) and CH2(1A1) where the existence of two UHF solutions indicates a necessity of description of the electronic correlation by more exact methods of quantum chemistry.

A correlation to predict the performance characteristics of centrifugal pumps handling slurries

1997 ◽  
Vol 211 (2) ◽  
pp. 147-157 ◽  
Author(s):  
K A Kazim ◽  
B Maiti ◽  
P Chand
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Suspended Solids ◽  
Reduction Factor ◽  
Performance Characteristics ◽  
Centrifugal Pumps ◽  
Pump Performance ◽  
New Correlation ◽  
Effect Of Particle Size ◽  
The Individual

Centrifugal pumps are being used increasingly for transportation of slurries through pipelines. To design a slurry handling system it is essential to have a knowledge of the effects of suspended solids on the pump performance. A new correlation to predict the head reduction factor for centrifugal pumps handling solids has been developed. This correlation takes into account the individual effect of particle size, particle size distribution, specific gravity and concentration of solids on the centrifugal pump performance characteristics. The range of validity of the correlation has been verified by experiment and by using experimental data available from the literature. The present correlation shows better agreement with the experimental data than existing correlations.

scholarly journals Benchmarking homogenization algorithms for monthly data

2012 ◽  
Vol 8 (1) ◽  
pp. 89-115 ◽  
Author(s):  
V. K. C. Venema ◽  
O. Mestre ◽  
E. Aguilar ◽  
I. Auer ◽  
J. A. Guijarro ◽  
...  
Keyword(s):  
Time Series ◽  
Performance Metrics ◽  
Linear Trend ◽  
Simulated Data ◽  
Integrated Approach ◽  
Global Network ◽  
Temperature And Precipitation ◽  
Skill Scores ◽  
Simulated Network ◽  
The Individual

Abstract. The COST (European Cooperation in Science and Technology) Action ES0601: advances in homogenization methods of climate series: an integrated approach (HOME) has executed a blind intercomparison and validation study for monthly homogenization algorithms. Time series of monthly temperature and precipitation were evaluated because of their importance for climate studies and because they represent two important types of statistics (additive and multiplicative). The algorithms were validated against a realistic benchmark dataset. The benchmark contains real inhomogeneous data as well as simulated data with inserted inhomogeneities. Random independent break-type inhomogeneities with normally distributed breakpoint sizes were added to the simulated datasets. To approximate real world conditions, breaks were introduced that occur simultaneously in multiple station series within a simulated network of station data. The simulated time series also contained outliers, missing data periods and local station trends. Further, a stochastic nonlinear global (network-wide) trend was added. Participants provided 25 separate homogenized contributions as part of the blind study. After the deadline at which details of the imposed inhomogeneities were revealed, 22 additional solutions were submitted. These homogenized datasets were assessed by a number of performance metrics including (i) the centered root mean square error relative to the true homogeneous value at various averaging scales, (ii) the error in linear trend estimates and (iii) traditional contingency skill scores. The metrics were computed both using the individual station series as well as the network average regional series. The performance of the contributions depends significantly on the error metric considered. Contingency scores by themselves are not very informative. Although relative homogenization algorithms typically improve the homogeneity of temperature data, only the best ones improve precipitation data. Training the users on homogenization software was found to be very important. Moreover, state-of-the-art relative homogenization algorithms developed to work with an inhomogeneous reference are shown to perform best. The study showed that automatic algorithms can perform as well as manual ones.

Abstract 434: Exposure To Air Pollutants And Mortality In Hypertensive Patients According To Demography: A 10 Year Case-crossover Study

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Martin C Wong ◽  
Wilson W Tam ◽  
Harry H Wang ◽  
Xiang Qian Lao ◽  
Mandy W Kwan ◽  
...  
Keyword(s):  
Air Pollution ◽  
Respiratory Disease ◽  
Air Pollutants ◽  
Health Care Services ◽  
Public Health Care ◽  
Cold Weather ◽  
Susceptible Population ◽  
Hypertensive Patients ◽  
Care Services ◽  
Case Crossover

Background: Relatively few studies have explored the relationship between air pollution and cause-specific mortality among hypertensive patients. This study evaluated whether short term exposures to nitrogen dioxide (NO2), ozone (O3), particulate matter <10 mm in diameter (PM10) were associated with higher risk of mortality among a large hypertensive patients. Methods: A total of 223,287 hypertensive patients who attended any public health-care services in Hong Kong and prescribed at least 1 antihypertensive agent for the first time between 2001 and 2005 were followed up until 2010. A time-stratified, bi-directional case-crossover design was adopted to study the association between environmental exposures and mortality outcomes. Results: For all-cause mortality, significant positive associations were observed for NO2 and PM10 at lag 0 to 3 days per 10 MIUg/m3 increase in concentration and the excess risks ranged from 1.187%- 2.501%. Significant positive associations were found for O3 at lag 1 and 2 days and the excess risks were 1.654% (95% C.I. 0.469%, 2.852%) and 1.207% (95% C.I. 0.025%, 2.404%), respectively. We found similarly positive associations between NO2 (excess risks: 1.786%-2.798%), PM10 (1.126%-1.847%), O3 (3.035%-3.355%) and mortality due to respiratory disease. In stratified analysis, these significant results were observed amongst those aged >65 years and in cold seasons only. Conclusions: Older hypertensive patients are susceptible to all-cause and respiratory disease-specific deaths from these air pollutants in cold weather. This implies urgent need for protective air pollution standards for this susceptible population.

scholarly journals Analysis of Equation of State for Carbon Nanotubes

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jeewan Chandra ◽  
Pooja Kapri Bhatt ◽  
Kuldeep Kholiya
Keyword(s):  
Experimental Data ◽  
Carbon Nanotubes ◽  
Thermal Expansion ◽  
Carbon Nanotube ◽  
Equation Of State ◽  
Compression Behavior ◽  
Nanotube Bundles ◽  
The Individual

Compression behavior of carbon nanotube bundles and individual carbon nanotubes within the bundle has been studied by using the Suzuki, Shanker, and usual Tait formulations. It is found that the Suzuki formulation is not capable of explaining the compression behavior of nanomaterials. Shanker formulation slightly improves the results obtained by the Suzuki formulation, but only usual Tait’s equation (UTE) of state gives results in agreement to the experimental data. The present study reveals that the product of bulk modules and the coefficient of volume thermal expansion remain constant for carbon nanotubes. It has also been found that the individual carbon nanotubes are less compressible than bundles of carbon nanotubes.

scholarly journals Wicksell's Problem in Local Stereology

2013 ◽  
Vol 45 (4) ◽  
pp. 925-944
Author(s):  
Ó. Thórisdóttir ◽  
M. Kiderlen
Keyword(s):  
Reference Point ◽  
Simulated Data ◽  
Domain Of Attraction ◽  
Spherical Particles ◽  
Section Profile ◽  
Particle Parameters ◽  
The Individual ◽  
The Relationship ◽  
Theoretical Results ◽  
Isotropic Random

Wicksell's classical corpuscle problem deals with the retrieval of the size distribution of spherical particles from planar sections. We discuss the problem in a local stereology framework. Each particle is assumed to contain a reference point and the individual particle is sampled with an isotropic random plane through this reference point. Both the size of the section profile and the position of the reference point inside the profile are recorded and used to recover the distribution of the corresponding particle parameters. Theoretical results concerning the relationship between the profile and particle parameters are discussed. We also discuss the unfolding of the arising integral equations, uniqueness issues, and the domain of attraction relations. We illustrate the approach by providing reconstructions from simulated data using numerical unfolding algorithms.

Is natural openness or trade policy good for the environment?

2011 ◽  
Vol 16 (6) ◽  
pp. 657-684 ◽  
Author(s):  
Steven Yamarik ◽  
Sucharita Ghosh
Keyword(s):  
Air Pollution ◽  
Trade Policy ◽  
Factor Endowment ◽  
Trade And Environment ◽  
Population Geography ◽  
Limited Impact ◽  
Individual Effects ◽  
Good For ◽  
The Individual ◽  
Trade Share

AbstractIn this paper, we estimate the individual effects of natural openness and trade policy on air pollution. Natural openness is the component of the trade share (imports and exports as a percentage of GDP) attributable to population, geography and factor endowment differences. We find that natural openness reduces air pollution, while trade policy has a limited impact. The implication is that ‘natural’ geographic and endowment differences play a more important role than deliberate trade policy decisions in explaining the trade and environment link.

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