scholarly journals Complex genetic patterns in human arise from a simple range-expansion model over continental landmasses

2017 ◽  
Author(s):  
Ricardo Kanitz ◽  
Elsa G Guillot ◽  
Sylvain Antoniazza ◽  
Samuel Neuenschwander ◽  
Jérôme Goudet
Keyword(s):  
East Africa ◽  
Isolation By Distance ◽  
Null Model ◽  
Real Data ◽  
Modern Human ◽  
Initial Population ◽  
Simple Diffusion ◽  
Simple Diffusion Model ◽  
Approximate Bayesian ◽  
Expansion Model

AbstractAlthough it is generally accepted that geography is a major factor shaping human genetic differentiation, it is still disputed how much of this differentiation is a result of a simple process of isolation-by-distance, and if there are factors generating distinct clusters of genetic similarity. We address this question using a geographically explicit simulation framework coupled with an Approximate Bayesian Computation approach. Based on six simple summary statistics only, we estimated the most probable demographic parameters that shaped modern human evolution under an isolation by distance scenario, and found these were the following: an initial population in East Africa spread and grew from 4000 individuals to 5.7 million in about 132 000 years. Subsequent simulations with these estimates followed by cluster analyses produced results nearly identical to those obtained in real data. Thus, a simple diffusion model from East Africa explains a large portion of the genetic diversity patterns observed in modern humans. We argue that a model of isolation by distance along the continental landmasses might be the relevant null model to use when investigating selective effects in humans and probably many other species.

scholarly journals Genetic Algorithm for Exam Timetabling Problem - A Specific Case for Japanese University Final Presentation Timetabling

2020 ◽  
Author(s):  
Jiawei LI ◽  
Tad Gonsalves
Keyword(s):  
Genetic Algorithm ◽  
Real Data ◽  
Initial Population ◽  
Exam Timetabling ◽  
Timetabling Problem ◽  
Training Approach ◽  
Chromosome Representation ◽  
Genetic Algorithm Approach ◽  
Hard And Soft Constraints ◽  
Microsoft Office

This paper presents a Genetic Algorithm approach to solve a specific examination timetabling problem which is common in Japanese Universities. The model is programmed in Excel VBA programming language, which can be run on the Microsoft Office Excel worksheets directly. The model uses direct chromosome representation. To satisfy hard and soft constraints, constraint-based initialization operation, constraint-based crossover operation and penalty points system are implemented. To further improve the result quality of the algorithm, this paper designed an improvement called initial population pre-training. The proposed model was tested by the real data from Sophia University, Tokyo, Japan. The model shows acceptable results, and the comparison of results proves that the initial population pre-training approach can improve the result quality.

scholarly journals A Simple Diffusion Model for Psychometric Analyses

2019 ◽  
Author(s):  
Udo Boehm ◽  
Maarten Marsman ◽  
Han van der Maas ◽  
Gunter Maris
Keyword(s):  
Diffusion Model ◽  
Functional Form ◽  
Response Times ◽  
Simple Diffusion ◽  
Regression Framework ◽  
Psychometric Analyses ◽  
Computer Based ◽  
Simple Diffusion Model ◽  
Source Of Information ◽  
Latent Regression

The emergence of computer-based assessments has made response times, in addition to response accuracies, available as a source of information about test takers’ latent abilities. The predominant approach to jointly account for response times and accuracies are statistical models. Substantive approaches such as the diffusion model, on the other hand, have been slow to gain traction due to their unwieldy functional form. In the present work we show how a single simplifying assumption yields a highly tractable diffusion model. This simple diffusion model is straightforward to analyse using Gibbs sampling and can be readily extended with a latent regression framework. We demonstrate the superior computational efficiency of our model compared to the standard diffusion model in a simulation study and showcase the theoretical merit of our model in an example application.

Estimation of the Rate of Hydrogen Penetration in a Welded API 5L Steel Pipe

2008 ◽  
Vol 273-276 ◽  
pp. 500-505
Author(s):  
Gabriel Plascencia ◽  
David Jaramillo ◽  
Felipe Hernández ◽  
Jorge Luis González
Keyword(s):  
Penetration Rate ◽  
Mechanical Damage ◽  
Electric Arc ◽  
Steel Pipe ◽  
Simple Diffusion ◽  
Rate Of Penetration ◽  
Ultrasonic Measurements ◽  
Hydrogen Penetration ◽  
Simple Diffusion Model ◽  
Damage To The Material

Hydrogen embrittlement is a common problem for the integrity of oil conducting pipes. In this work, we estimate the rate of hydrogen penetration into an API 5L steel pipe welded by electric arc. The hydrogen penetration was estimated by means of data taken from ultrasonic measurements. As expected, the steel pipe becomes more brittle as the hydrogen penetration rate does so. A simple diffusion model was developed. The model confirms the strong dependency between the rate of penetration and the mechanical damage to the material.

scholarly journals A Middle Palaeolithic burial of a modern human at Taramsa Hill, Egypt

Antiquity ◽  
1998 ◽  
Vol 72 (277) ◽  
pp. 475-484 ◽  
Author(s):  
P. M. Vermeersch ◽  
E. Paulissen ◽  
P. Van Peer ◽  
S. Stokes ◽  
C. Charlier ◽  
...  
Keyword(s):  
East Africa ◽  
Late Pleistocene ◽  
Modern Human ◽  
Nile Valley ◽  
Middle Palaeolithic ◽  
African Origin ◽  
Modern Humans ◽  
Origin Of Modern Humans ◽  
Clear Relation ◽  
Aeolian Sands

Discussion about a possible African origin of modern humans is hampered by the lack of Late Pleistocene skeletal material from the Nile valley, the likely passage-way from East Africa to Asia and Europe. Here we report the discovery of a burial of an anatomically modern child from southern Egypt. Its clear relation with Middle Palaeolithic chert extraction activities and a series of OSL dates, from correlative aeolian sands, suggests an age between 49,800 and 80,400 years ago, with a mean age of 55,000.

A Simple Diffusion Model of Surface Modification by Plasma

1997 ◽  
Vol 159 (2) ◽  
pp. 405-416 ◽  
Author(s):  
V. I. Dimitrov ◽  
J. D'Haen ◽  
G. Knuyt ◽  
C. Quaeyhaegens ◽  
L. M. Stals
Keyword(s):  
Surface Modification ◽  
Diffusion Model ◽  
Simple Diffusion ◽  
Simple Diffusion Model

A model of potassium ion efflux during exercise of skeletal muscle

1979 ◽  
Vol 236 (1) ◽  
pp. R83-R90 ◽  
Author(s):  
Y. Hazeyama ◽  
H. V. Sparks
Keyword(s):  
Time Course ◽  
Ion Pump ◽  
K Uptake ◽  
Direct Stimulation ◽  
Nernst Equation ◽  
Vasoactive Agent ◽  
Simple Diffusion ◽  
Pump Activity ◽  
Stimulation Period ◽  
Simple Diffusion Model

Potassium (K+) is a vasoactive agent and is released from muscle cells during exercise. A simple diffusion model does not predict the time course of K+ efflux during exercise, which decreases as the exercise progresses. We constructed a mathematical model using the concept of an active Na+-K+ ion pump to account for the decreased efflux during and uptake after exercise. Passive fluxes are calculated by the Nernst equation. Active fluxes are constrained to balance these passive fluxes at rest. The pump activity increases as either extracellular K+ or intracellular Na+ concentration increases. To test the model, the venous K+ efflux profile was simulated for direct stimulation (4/s) of the anterior calf mus cles of dogs. The model simulated the K+ release during the stimulation period and [K+] undershoot after the stimulation. The active Na+-K+ ATPase transport concept used in the model was further tested by observing K+ efflux after administration of ouabain. Ouabain infusion decreased K+ uptake during exercise slightly and abolished [K+] undershoot after the stimulation. These experimental data were matched by the model only if a discontinuous effect of ouabain is assumed. This suggests that ouabain may more completely block the sensitivity of the pump to intracellular [Na+] than to extracellular [K+].

scholarly journals Modeling the Municipal Waste Collection Using Genetic Algorithms

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 513
Author(s):  
Elisabete Alberdi ◽  
Leire Urrutia ◽  
Aitor Goti ◽  
Aitor Oyarbide-Zubillaga
Keyword(s):  
Genetic Algorithm ◽  
Variable Neighborhood Search ◽  
Real Data ◽  
Municipal Waste ◽  
Neighborhood Search ◽  
Initial Population ◽  
Waste Collection ◽  
Reduction Of Emissions ◽  
Apparent Reasons ◽  
Unsolved Issue

Calculating adequate vehicle routes for collecting municipal waste is still an unsolved issue, even though many solutions for this process can be found in the literature. A gap still exists between academics and practitioners in the field. One of the apparent reasons why this rift exists is that academic tools often are not easy to handle and maintain by actual users. In this work, the problem of municipal waste collection is modeled using a simple but efficient and especially easy to maintain solution. Real data have been used, and it has been solved using a Genetic Algorithm (GA). Computations have been done in two different ways: using a complete random initial population, and including a seed in this initial population. In order to guarantee that the solution is efficient, the performance of the genetic algorithm has been compared with another well-performing algorithm, the Variable Neighborhood Search (VNS). Three problems of different sizes have been solved and, in all cases, a significant improvement has been obtained. A total reduction of 40% of itineraries is attained with the subsequent reduction of emissions and costs.

STRUCTURAL AND MAGNETIC PROPERTIES OF SINGLE CRYSTAL RARE EARTH Gd-Y SUPERLATTICES

1985 ◽  
Vol 56 ◽  
Author(s):  
J. Kwo ◽  
D. B. McWhan ◽  
M. Hong ◽  
E. M. Gyorgy ◽  
F. J. DiSalvo
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Magnetic Ordering ◽  
X Ray Diffraction ◽  
Simple Diffusion ◽  
X Ray ◽  
Composition Modulation ◽  
Strain Modulation ◽  
Simple Diffusion Model ◽  
Magnetization Behavior

AbstractHigh quality single crystal rare earth Gd-Y superlattices with wavelength varying from 8to 42 atomic layers were grown by the recently developed metal molecular beam epitaxy technique. The crystallinity and coherence of the superlattices were examined by X-ray diffraction, and the profiles of composition modulation and strain modulation were determined from a quantitative analysis based on a simple diffusion model for the Gd-Y interfaces. The sharp boundaries achieved in these metallic superlattices are approaching those in semiconductor superlattices. The various in-plane magnetization behavior at low fieldsamong superlattices of different wavelengths suggests the possible presence of new magnetic ordering structures as caused by the artificial modulation.

A simple diffusion model showing anomalous scaling

2008 ◽  
Vol 15 (8) ◽  
pp. 082308 ◽  
Author(s):  
G. Rowlands ◽  
J. C. Sprott
Keyword(s):  
Diffusion Model ◽  
Anomalous Scaling ◽  
Simple Diffusion ◽  
Simple Diffusion Model
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