Computer simulations of the ROUSE model: An analytic simulation technique and a comparison between the error variance—covariance and bootstrap methods for estimating parameter confidence

ABSTRACTThe understanding and prediction of complex nanostructured self-assemblies such as colloidal suspensions, micelles, immiscible mixtures, microemulsions, etc., represent a challenge for conventional methods of simulation due to the presence of different time scales in their dynamics.We have recently successfully applied a novel computer simulations technique, Dissipative Particle Dynamics (DPD), to model the behavior of diblockcopolymers at the water/oil interface. With the use of a simple model we have performed simulations of polymer/water/oil systems at different concentrations.We present the results of nanoscale “coarse-grained” simulations with DPD. DPD is a mesoscale simulation technique that has been introduced in order to simulate three-dimensional structures of organic polymer aggregates.In DPD the polymer is modeled using particles which are interacting by conservative, dissipative and random forces. Particles are not regarded as molecules but rather as droplets or nanoclusters of molecules.We have successfully applied this technique to simulate the three-dimensional structures of microemulsions, e.g. the bicontinuous phase of a surfactant in water and oil, in domains of less than 100 nm. The different structures of the polymer/water/oil system were effectively characterized with DPD and are in remarkable agreement with the experiment.The DPD method proofed to be a reliable tool to get a better understanding of the nanostructure of self-assemblies and is therefore applicable to support the often complicated experiments or even to obtain experimentally unavai1able data.

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Some Implications of Distinguishing Between Unexplained Variance That Is Systematic or Random

Educational and Psychological Measurement ◽

10.1177/0013164417691573 ◽

2017 ◽

Vol 78 (3) ◽

pp. 482-503 ◽

Cited By ~ 4

Author(s):

David Trafimow

Keyword(s):

Computer Simulations ◽

Variance Components ◽

Measurement Theory ◽

Error Variance ◽

Total Variance ◽

Classical Measurement ◽

Observable Data ◽

Independent Variable ◽

Unexplained Variance ◽

Random Variance

Because error variance alternatively can be considered to be the sum of systematic variance associated with unknown variables and randomness, a tripartite assumption is proposed that total variance in the dependent variable can be partitioned into three variance components. These are variance in the dependent variable that is explained by the independent variable, variance in the dependent variable that is unexplained but systematic (associated with variance in unknown variables), and random variance. Based on the tripartite assumption, classical measurement theory, and simple mathematics, it is shown that these components can be estimated using observable data. Mathematical and computer simulations illustrate some of the important issues and implications.

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A note on the estimation by simulation technique of the optimal colostrum dose and feeding time at first feeding after the calf's birth

Animal Science ◽

10.1017/s0003356100029305 ◽

1970 ◽

Vol 12 (4) ◽

pp. 661-664 ◽

Cited By ~ 17

Author(s):

V. Kruse

Keyword(s):

Birth Weight ◽

Computer Simulations ◽

Simulation Technique ◽

Feeding Time ◽

Early Feeding ◽

First Feeding ◽

Weight Concentration

SUMMARYComputer simulations using parameters based on results from experiments showed that by chance a certain frequency of hypo-gammaglobulinaemia would always occur. This was due to variations in birth weight, concentration of immunoglobulin in the ingested colostrum, amount of colostrum offered, and age at first feeding. It was not necessarily associated with an absorption block as sometimes postulated. The probability of an individual getting hypogammaglobulinaemia can be minimized by early feeding of a large quantity of colostrum at the first feeding after birth.

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A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055904 ◽

1982 ◽

Vol 40 ◽

pp. 722-723 ◽

Cited By ~ 1

Author(s):

R. Gronsky

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Resolution ◽

Computer Simulations ◽

Structural Characteristics ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

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Determination of the Burgers vector of a dislocation in a Fe-Mn alloy by weak-beam image in HVEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108799 ◽

1978 ◽

Vol 36 (1) ◽

pp. 330-331

Author(s):

Y. Ishida ◽

H. Ishida ◽

K. Kohra ◽

H. Ichinose

Keyword(s):

High Order ◽

Simulation Technique ◽

The Other ◽

Image Simulation ◽

Diffraction Vector ◽

Burgers Vector ◽

Weak Beam ◽

Beam Image ◽

Edge Component

IntroductionA simple and accurate technique to determine the Burgers vector of a dislocation has become feasible with the advent of HVEM. The conventional image vanishing technique(1) using Bragg conditions with the diffraction vector perpendicular to the Burgers vector suffers from various drawbacks; The dislocation image appears even when the g.b = 0 criterion is satisfied, if the edge component of the dislocation is large. On the other hand, the image disappears for certain high order diffractions even when g.b ≠ 0. Furthermore, the determination of the magnitude of the Burgers vector is not easy with the criterion. Recent image simulation technique is free from the ambiguities but require too many parameters for the computation. The weak-beam “fringe counting” technique investigated in the present study is immune from the problems. Even the magnitude of the Burgers vector is determined from the number of the terminating thickness fringes at the exit of the dislocation in wedge shaped foil surfaces.

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Multislice calculations for quasi-periodic and non-periodic objects

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173820 ◽

1990 ◽

Vol 48 (4) ◽

pp. 138-139

Author(s):

R. Herrera ◽

A. Gómez

Keyword(s):

Electron Diffraction ◽

Computer Simulations ◽

Periodic Table ◽

Amorphous Materials ◽

Space Group ◽

Essential Step ◽

Shape Effects ◽

Atomic Scattering ◽

Diffraction Patterns ◽

Periodic Continuation

Computer simulations of electron diffraction patterns and images are an essential step in the process of structure and/or defect elucidation. So far most programs are designed to deal specifically with crystals, requiring frequently the space group as imput parameter. In such programs the deviations from perfect periodicity are dealt with by means of “periodic continuation”.However, for many applications involving amorphous materials, quasiperiodic materials or simply crystals with defects (including finite shape effects) it is convenient to have an algorithm capable of handling non-periodicity. Our program “HeGo” is an implementation of the well known multislice equations in which no periodicity assumption is made whatsoever. The salient features of our implementation are: 1) We made Gaussian fits to the atomic scattering factors for electrons covering the whole periodic table and the ranges [0-2]Å−1 and [2-6]Å−1.

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Computer simulations for the TEM bend contour technique

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100163137 ◽

1996 ◽

Vol 54 ◽

pp. 134-135

Author(s):

Vladimir Yu. Kolosov ◽

Anders R. Thölén

Keyword(s):

Computer Simulations ◽

Real Space ◽

Advantages And Disadvantages ◽

Short Overview ◽

Diffraction Contrast ◽

Beam Method ◽

Convergent Beam ◽

Contour Technique

In this paper we give a short overview of two TEM applications utilizing the extinction bend contour technique (BC) giving the advantages and disadvantages; especially we consider two areas in which the BC technique remains unique. Special attention is given to an approach including computer simulations of TEM micrographs.BC patterns are often observed in TEM studies but are rarely exploited in a serious way. However, this type of diffraction contrast was one of the first to be used for analysis of imperfections in crystalline foils, but since then only some groups have utilized the BC technique. The most extensive studies were performed by Steeds, Eades and colleagues. They were the first to demonstrate the unique possibilities of the BC method and named it real space crystallography, which developed later into the somewhat similar but more powerful convergent beam method. Maybe, due to the difficulties in analysis, BCs have seldom been used in TEM, and then mainly to visualize different imperfections and transformations.

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Measuring the Big Five in Self-Report and Other Ratings

European Journal of Psychological Assessment ◽

10.1027//1015-5759.16.1.31 ◽

2000 ◽

Vol 16 (1) ◽

pp. 31-43 ◽

Cited By ~ 24

Author(s):

Claudio Barbaranelli ◽

Gian Vittorio Caprara

Keyword(s):

Big Five ◽

Structural Equation ◽

Structural Equation Models ◽

Error Variance ◽

The Self ◽

Self Report ◽

Sources Of Information ◽

Third Person ◽

Fit Indexes ◽

Response Modes

Summary: The aim of the study is to assess the construct validity of two different measures of the Big Five, matching two “response modes” (phrase-questionnaire and list of adjectives) and two sources of information or raters (self-report and other ratings). Two-hundred subjects, equally divided in males and females, were administered the self-report versions of the Big Five Questionnaire (BFQ) and the Big Five Observer (BFO), a list of bipolar pairs of adjectives ( Caprara, Barbaranelli, & Borgogni, 1993 , 1994 ). Every subject was rated by six acquaintances, then aggregated by means of the same instruments used for the self-report, but worded in a third-person format. The multitrait-multimethod matrix derived from these measures was then analyzed via Structural Equation Models according to the criteria proposed by Widaman (1985) , Marsh (1989) , and Bagozzi (1994) . In particular, four different models were compared. While the global fit indexes of the models were only moderate, convergent and discriminant validities were clearly supported, and method and error variance were moderate or low.

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