scholarly journals Effects of Selection and Linkage on Degree of Inbreeding

1966 ◽  
Vol 19 (2) ◽  
pp. 307 ◽  
Author(s):  
JL Gill ◽  
BA Clemmer
Keyword(s):  
Monte Carlo ◽  
Artificial Selection ◽  
Small Populations ◽  
Joint Effects ◽  
Two Factors ◽  
Coefficient Of Inbreeding

Monte Carlo computer techniques were employed to simulate inbreeding in small populations under regimes consisting of combinations of three degrees of linkage and three intensities of selection. Selection and linkage each significantly increased the rate of inbreeding in populations of a given size, although the effect of linkage was larger. Linkage contributions to bias in the coefficient of inbreeding may exceed those of selection in general, if one restricts comparisons to levels of the two factors that are similar with respect to the range of their possible values. Linkage also had a much larger effect than did selection on inflation of the variance of estimates of the coefficient of inbreeding. The joint effects of selection and linkage can have severe implications with respect to inbreeding in artificial selection programmes.

The Interaction of Word Frequency and Stimulus Quality in the Lexical Decision Task: Now you See It, Now you Don't

1988 ◽  
Vol 40 (4) ◽  
pp. 757-770 ◽  
Author(s):  
J. M. Wilding
Keyword(s):  
Word Recognition ◽  
Lexical Decision ◽  
Lexical Decision Task ◽  
Word Frequency ◽  
Decision Task ◽  
Stimulus Quality ◽  
Joint Effects ◽  
Two Factors

Two experiments are reported that examined the joint effects of word frequency and stimulus quality in the context of a lexical decision task. In the first experiment the interval between response to a stimulus and onset of the next stimulus was 0.8 sec, and the effect of the two factors was additive. In the second this interval was 3.3 sec, and the effect of reducing stimulus quality was greater for infrequent words than for frequent words. This is similar to the result of Norris (1984). The inability of current models of word recognition to explain this finding is discussed.

scholarly journals The joint effects of two factors in the aetiology of oesophageal cancer in Japan.

1988 ◽  
Vol 42 (4) ◽  
pp. 355-364 ◽  
Author(s):  
K Nakachi ◽  
K Imai ◽  
Y Hoshiyama ◽  
T Sasaba
Keyword(s):  
Oesophageal Cancer ◽  
Joint Effects ◽  
Two Factors

Fatigue Life Reliability Analysis of Submarine Cone-Cylinder Shell

2012 ◽  
Vol 479-481 ◽  
pp. 2001-2004
Author(s):  
Zhi Yong Zhang ◽  
Tian Shu Song ◽  
Yang He
Keyword(s):  
Monte Carlo ◽  
Fatigue Life ◽  
Monte Carlo Method ◽  
Fracture Mechanics ◽  
Reliability Analysis ◽  
The Other ◽  
New Method ◽  
Probabilistic Fracture Mechanics ◽  
Two Factors

A new method is presented in the paper. The fatigue life reliability of submarine cone-cylinder shell is investigated, based on the combination between the methods of conventional Monte Carlo and classical probabilistic fracture mechanics. Firstly, Monte Carlo method is employed to obtain the reliability of given initial fatigue life. Secondly, the two induced factors M1 and M2 in the paper are estimated according to the initial fatigue life and the reliability. Thirdly, based on the two factors, the other fatigue life reliability is obtained by using classical probabilistic fracture mechanics method. Finally, numerical cases show that the proposed method is more efficient without accuracy loss for fatigue life reliability compared with Monte Carlo method. This method can also be applied to predict the fatigue life reliability of analogue structures.

scholarly journals The effect of selected linked locus on heterozygosity of neutral alleles (the hitch-hiking effect)

1975 ◽  
Vol 25 (3) ◽  
pp. 313-325 ◽  
Author(s):  
Tomoko Ohta ◽  
Motoo Kimura
Keyword(s):  
Monte Carlo ◽  
Natural Selection ◽  
Mathematical Theory ◽  
Recombination Fraction ◽  
Small Populations ◽  
Selection Coefficient ◽  
Monte Carlo Experiments ◽  
Neutral Locus ◽  
Marker Loci ◽  
Neutral Marker

SUMMARYA diffusion model was developed to investigate the effect of a mutant substitution by natural selection on heterozygosity at a linked neutral locus. Using this theory, we made extensive numerical analyses to compute the expected total heterozygosity (i.e. the sum of the fraction of heterozygotes over all generations until fixation or loss) at the neutral locus. It was shown that the hitch-hiking effect is generally unimportant as a mechanism for reducing heterozygosity. The effect becomes significant only when the recombination fraction between the selected and the neutral marker loci is smaller than the selection coefficient. In order to check the validity of the mathematical theory, Monte Carlo experiments were performed, and the results were in agreement. It has been suggested that linkage is important only in transient small populations such as at the time of speciation.

A CLOSER LOOK AT THE EPPS EFFECT

2003 ◽  
Vol 06 (01) ◽  
pp. 87-102 ◽  
Author(s):  
ROBERTO RENÒ
Keyword(s):  
Monte Carlo ◽  
Exchange Rate ◽  
Fourier Analysis ◽  
Foreign Exchange ◽  
High Frequency ◽  
Stock Price ◽  
Sampling Frequency ◽  
Original Method ◽  
Foreign Exchange Rate ◽  
Two Factors

Epps [17] reported empirical evidence that stock correlations decrease when sampling frequency increases. This phenomenon, named Epps effect, has been observed in several markets. In this paper, the dynamics underlying the Epps effect are investigated. Using Monte Carlo simulations and the analysis of high frequency foreign exchange rate and stock price data, it is shown that the Epps effect can largely be explained by two factors: the non-synchronicity of price observations and the existing lead-lag relationship between asset prices. In order to compute co-volatilities, an original method based upon the Fourier analysis is adopted. This method performs well in estimating correlations precisely, as illustrated by simulated experiments. Being naturally embedded in the frequency domain, this estimator is well suited to the study of the Epps effect.

scholarly journals Minimizing Inbreeding by Managing Genetic Contributions Across Generations

Genetics ◽  
2003 ◽  
Vol 164 (4) ◽  
pp. 1589-1595 ◽  
Author(s):  
Leopoldo Sánchez ◽  
Piter Bijma ◽  
John A Woolliams
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Random Mating ◽  
Sampling Variance ◽  
Small Populations ◽  
Efficient Approach ◽  
New Strategy ◽  
Census Number ◽  
Genetic Contributions

Abstract Here we present the strategy that achieves the lowest possible rate of inbreeding (ΔF) for a population with unequal numbers of sires and dams with random mating. This new strategy results in a ΔF as much as 10% lower than previously achieved. A simple and efficient approach to reducing inbreeding in small populations with sexes of unequal census number is to impose a breeding structure where parental success is controlled in each generation. This approach led to the development of strategies for selecting replacements each generation that were based upon parentage, e.g., a son replacing its sire. This study extends these strategies to a multigeneration round robin scheme where genetic contributions of ancestors to descendants are managed to remove all uncertainties about breeding roles over generations; i.e., male descendants are distributed as equally as possible among dams. In doing so, the sampling variance of genetic contributions within each breeding category is eliminated and consequently ΔF is minimized. Using the concept of long-term genetic contributions, the asymptotic ΔF of the new strategy for random mating, M sires and d dams per sire, is ϕ/(12M), where ϕ = [1 + 2(¼)d]. Predictions were validated using Monte Carlo simulations. The scheme was shown to achieve the lowest possible ΔF using pedigree alone and showed that further reductions in ΔF below that obtained from random mating arise from preferential mating of relatives and not from their avoidance.

scholarly journals A Monte Carlo Evaluation of Predicted Selection Response

1965 ◽  
Vol 18 (5) ◽  
pp. 999 ◽  
Author(s):  
JL Gill
Keyword(s):  
Monte Carlo ◽  
Mathematical Formulation ◽  
Environmental Variation ◽  
Selection Response ◽  
Small Populations ◽  
Computer Programme ◽  
Finite Populations ◽  
Genetic Progress ◽  
Monte Carlo Evaluation

This study utilizes a computer programme that simulates the effects of selection, linkage, and environmental variation on the genetic progress of finite populations. The results, with respect to selection advance and the inbreeding that occurs in small populations, have been discussed previously (Gill 1965). In the present paper, the correspondence of Monte Carlo results to the hypothetical progress predicted according to a mathematical formulation given by Griffing (1960) is evaluated.

The Computation of the Skirt in VP-SEM OR ESEM With Monte Carlo Simulations

1999 ◽  
Vol 5 (S2) ◽  
pp. 296-297
Author(s):  
Raynald Gauvin
Keyword(s):  
Monte Carlo ◽  
Electron Beam ◽  
Beam Energy ◽  
Single Scattering ◽  
Gas Composition ◽  
Monte Carlo Program ◽  
Elastic Collisions ◽  
Electron Trajectories ◽  
Two Factors ◽  
Working Distance

It is well known that the interaction of the electron beam with the gas in the VP-SEM or ESEM generate the so-called skirt as a result of the elastic collisions between the electrons and the molecules. Since the electrons in the skirt hit the specimen far away from the electron beam, they degrade the resolution of the analyses performed in the VPSEM or ESEM. However, the magnitude and the shape of the skirt are still a matter of controversy despite the fundamental importance of knowing these two factors. In this context, a Monte Carlo program has been developed to simulate the interaction of the electron beam with a gas as a function of the gas composition, gas pressure, electron beam energy and working distance (in reality, we should talk of the total distance traveled by the electron beam in the gas). This Monte Carlo program used a single scattering approach considering elastic collisions only since energy loss is negligible owing to the low density of the gas. 10 millions electron trajectories have been simulated for each conditions.

Artificial selection for intrinsic aerobic endurance running capacity in rats

2001 ◽  
Vol 5 (1) ◽  
pp. 45-52 ◽  
Author(s):  
LAUREN GERARD KOCH ◽  
STEVEN L. BRITTON
Keyword(s):  
Body Weight ◽  
Artificial Selection ◽  
High Capacity ◽  
Founder Population ◽  
Endurance Running ◽  
Family Selection ◽  
High Line ◽  
Selection For ◽  
Coefficient Of Inbreeding

Artificial selection for intrinsic aerobic endurance running capacity was started using genetically heterogeneous N:NIH stock of rats as a founder population ( n = 168). Selection for low and high capacity was based upon distance run to exhaustion on a motorized treadmill using a velocity-ramped running protocol. The starting velocity was 10 m/min and was increased by 1 m/min every 2 min (slope was constant at 15°). At each generation, within-family selection was practiced using 13 families for both the low and high lines. A rotational breeding paradigm maintained the coefficient of inbreeding at less than 1% per generation. On average the founder population ran to exhaustion in 355 ± 11 m. Six generations of selection produced lines that differed in running capacity by 171%, with most of the change occurring in the high line. At generation 6 the low line ran 310 ± 8 m and the high line 839 ± 21 m at exhaustion. Selection for running capacity produced changes in body weight as a correlated trait. By generation 6, the low-line females were 20% heavier than the high-line females, and the low-line males were 16% heavier than the high-line males.

scholarly journals Simulation of Genetic Systems by Automatic Digital Computers VI. Epistasis

1960 ◽  
Vol 13 (2) ◽  
pp. 150 ◽  
Author(s):  
AS Fraser
Keyword(s):  
Monte Carlo ◽  
Population Size ◽  
Monte Carlo Methods ◽  
Slow Rate ◽  
Genetic System ◽  
Small Populations ◽  
Gene Frequencies ◽  
Genetic Systems ◽  
The Relationship ◽  
Digital Computers

Simulation, by Monte Carlo methods, of the effect on the genotype of seleotion against phenotypic extremes has shown that selection will lead to fixation of a simple additive genetic system at an extremely slow rate in all but very small populations. In oomplex epistatio systems, such selection operates to modify the relation of the genotype to the phenotype. The relationship beoomes an S�shaped function. The efficienoy of seleotion is independent of population size. The deviation from initial gene frequencies due to selection is far less per unit decrease of phenotypio variability in the epistatic than in the additive lines.

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