scholarly journals Maintenance of genetic variability under strong stabilizing selection: a two-locus model.

Genetics ◽  
1993 ◽  
Vol 134 (1) ◽  
pp. 377-386 ◽  
Author(s):  
S Gavrilets ◽  
A Hastings
Keyword(s):  
Genetic Variability ◽  
Fitness Function ◽  
Additive Genetic Variance ◽  
Mean Value ◽  
Stabilizing Selection ◽  
Locus Model ◽  
Large Level ◽  
The Difference ◽  
Different Characteristics ◽  
The Relationship

Abstract We study a two locus model with additive contributions to the phenotype to explore the relationship between stabilizing selection and recombination. We show that if the double heterozygote has the optimum phenotype and the contributions of the loci to the trait are different, then any symmetric stabilizing selection fitness function can maintain genetic variability provided selection is sufficiently strong relative to linkage. We present results of a detailed analysis of the quadratic fitness function which show that selection need not be extremely strong relative to recombination for the polymorphic equilibria to be stable. At these polymorphic equilibria the mean value of the trait, in general, is not equal to the optimum phenotype, there exists a large level of negative linkage disequilibrium which "hides" additive genetic variance, and different equilibria can be stable simultaneously. We analyze dependence of different characteristics of these equilibria on the location of optimum phenotype, on the difference in allelic effect, and on the strength of selection relative to recombination. Our overall result that stabilizing selection does not necessarily eliminate genetic variability is compatible with some experimental results where the lines subject to strong stabilizing selection did not have significant reductions in genetic variability.

Dynamics of genetic variability in two-locus models of stabilizing selection.

Genetics ◽  
1994 ◽  
Vol 138 (2) ◽  
pp. 519-532
Author(s):  
S Gavrilets ◽  
A Hastings
Keyword(s):  
Linkage Disequilibrium ◽  
Initial Conditions ◽  
Fitness Function ◽  
Stabilizing Selection ◽  
Phenotypic Evolution ◽  
Phenotypic Characteristics ◽  
Locus Model ◽  
Straight Line ◽  
The Difference ◽  
Slow Evolution

Abstract We study a two locus model, with additive contributions to the phenotype, to explore the dynamics of different phenotypic characteristics under stabilizing selection and recombination. We demonstrate that the interaction of selection and recombination results in constraints on the mode of phenotypic evolution. Let Vg be the genic variance of the trait and CL be the contribution of linkage disequilibrium to the genotypic variance. We demonstrate that, independent of the initial conditions, the dynamics of the system on the plane (Vg, CL) are typically characterized by a quick approach to a straight line with slow evolution along this line afterward. We analyze how the mode and the rate of phenotypic evolution depend on the strength of selection relative to recombination, on the form of fitness function, and the difference in allelic effect. We argue that if selection is not extremely weak relative to recombination, linkage disequilibrium generated by stabilizing selection influences the dynamics significantly. We demonstrate that under these conditions, which are plausible in nature and certainly the case in artificial stabilizing selection experiments, the model can have a polymorphic equilibrium with positive linkage disequilibrium that is stable simultaneously with monomorphic equilibria.

scholarly journals PENGGUNAAN ANALISIS PONT PADA POPULASI MAHASISWA SUKU MINANG DI FAKULTAS KEDOKTERAN GIGI UNIVERSITAS ANDALAS

2019 ◽  
Vol 1 (2) ◽  
pp. 126-141
Author(s):  
Murniwati Murniwati ◽  
Maya Syafitri
Keyword(s):  
Mean Value ◽  
Dental Arch ◽  
Cross Sectional ◽  
Arch Width ◽  
The Difference ◽  
Cross Sectional Design ◽  
Dental Arch Width ◽  
Different Characteristics ◽  
Cast Analysis ◽  
Dental Cast

Dental cast analysis is one of the important thing in orthodontic treatments. One of the dental cast analysis which is usually used is Pont analysis, proposed in 1909. Pont did his research to a population in French which is Caucasian and stated that his theory needs to be tested to another ethnics to verify the applicability of Pont analysis to that population. On each race, there are some specific physical characteristics such as the form and width of dentition and dental arch. Minang population are Mongolian who has the different characteristics of dentition and dental arch with the Caucasians.The aim of this study is to identify whether Pont analysis is precise to be used to Minang population. Method : Cross-sectional design was used in this study. This study was done to 65 upper dental casts from Minang student at the Faculty of Dentistry Andalas University who met the inclusion criteria. The difference between the measured and the calculated interpremolar and intermolar arch width was tested with paired T test with the significant value of 0.05 (p=0.05). Result : Mean value of interpremolar width was 37.8838 ± 2.29042 mm and intermolar width was 47.6046±3.18780 mm. The result of statistical analysis showed that there is no significant differences of the measured and the calculated interpremolar and intermolar width of Minang Student at Faculty of Dentistry Andalas University (p>0.05). Conclusion : Pont analysis can be used as one of the dental cast analysis in orthodontic diagnosis and treatment planning to Minang population. It is suggested to do a further research to identify lower dental arch form of the Minang population whose upper dental arch width equals to the predicted arch width according to Pont’s formula.

scholarly journals The relationship between circulating estradiol and thyroid autoimmunity in males

2014 ◽  
Vol 170 (1) ◽  
pp. 63-67 ◽  
Author(s):  
La-or Chailurkit ◽  
Wichai Aekplakorn ◽  
Boonsong Ongphiphadhanakul
Keyword(s):  
Thyroid Autoimmunity ◽  
Serum Levels ◽  
Mean Value ◽  
Thyroid Peroxidase ◽  
Test Results ◽  
Autoimmune Thyroid ◽  
Thyroid Peroxidase Antibody ◽  
Thyroglobulin Antibody ◽  
The Difference ◽  
The Relationship

IntroductionAlthough autoimmune thyroid disease is less common in males, it is unclear whether estrogen contributes to the difference in susceptibility among males.ObjectiveTo examine whether circulating estradiol (E2) is related to thyroid autoimmunity in males.Patients and methodsOne-thousand two-hundred and sixty-three males aged 15–94 years were studied. Serum levels of E2, TSH receptor antibody (TRAb), thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb), free thyroxine (FT4), and TSH were measured by ELISA.ResultsCirculating E2varied widely in males, ranging 18.4–403.7 pmol/l with a mean value of 136.2±51.7 pmol/l. E2increased with age (r=0.18,P<0.001). No relationship between E2and BMI was found. When comparing the difference in E2according to the test results of TRAb, TPOAb, and TgAb, it was found that E2was significantly higher in subjects with positive TRAb (TRAb positive, E2=170.3±59.8 pmol/l; TRAb negative, E2=134.0±50.6 pmol/l;P<0.001). No difference in E2was demonstrated according to the results of TPOAb or TgAb. Logistic regression analysis showed that E2was a determinant of positive TRAb, independent of age and BMI. There was no relationship between serum E2and TSH or FT4. However, E2was negatively related to TSH (r=−0.45,P<0.01) in subjects whose TSH levels fell below the reference range (0.3–4.2 mIU/l).ConclusionHigher circulating E2is related to thyroid autoimmunity in males as reflected by positive TRAb.

scholarly journals The maintenance of genetic variability in two-locus models of stabilizing selection.

Genetics ◽  
1989 ◽  
Vol 122 (1) ◽  
pp. 235-248 ◽  
Author(s):  
T Nagylaki
Keyword(s):  
Genetic Variability ◽  
Fitness Function ◽  
Critical Value ◽  
Complete Classification ◽  
Stabilizing Selection ◽  
Random Mutation ◽  
Major Locus ◽  
Fitness Functions ◽  
Existence And Stability

Abstract The maintenance of genetic variability at two diallelic loci under stabilizing selection is investigated. Generations are discrete and nonoverlapping; mating is random; mutation and random genetic drift are absent; selection operates only through viability differences. The determination of the genotypic values is purely additive. The fitness function has its optimum at the value of the double heterozygote and decreases monotonically and symmetrically from its optimum, but is otherwise arbitrary. The resulting fitness scheme is identical to the symmetric viability model. Linkage disequilibrium is neglected, but the results are otherwise exact. Explicit formulas are found for all the equilibria, and explicit conditions are derived fro their existence and stability. A complete classification of the six possible global convergence patterns is presented. In addition to the symmetric equilibrium (with gene frequency 1/2 at both loci), a pair of unsymmetric equilibria may exist; the latter are usually, but not always, unstable. If the ratio of the effect of the major locus to that of the minor one exceeds a critical value, both loci will be stably polymorphic. If selection is weak at the minor locus, the more rapidly the fitness function decreases near the optimum, the lower is this critical value; for rapidly decreasing fitness functions, the critical value is close to one. If the fitness function is smooth at the optimum, then a stable polymorphism exists at both loci only if selection is strong at the major locus.

scholarly journals STABILIZING SELECTION FOR PUPA WEIGHT IN TRIBOLIUM CASTANEUM

Genetics ◽  
1977 ◽  
Vol 87 (2) ◽  
pp. 327-341
Author(s):  
Pamela K Kaufman ◽  
Franklin D Enfield ◽  
Ralph E Comstock
Keyword(s):  
Genetic Variability ◽  
Tribolium Castaneum ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Heterozygote Advantage ◽  
Stabilizing Selection ◽  
Phenotypic Variance ◽  
Sources Of Variation ◽  
Selection For

ABSTRACT Ninety-five generations of stabilizing selection for pupa weight in Tribolium castaneum resulted in a significant decrease in phenotypic variance, moderate reductions in additive genetic variance, but only slight changes in heritability for the trait. Sterility was significantly lower and the average number of live progeny per fertile mating was significantly higher in populations where stabilizing selection was practiced as compared with random selected populations. The results indicate that more genetic variability is being maintained than would be expected unless a fraction of the genes have a heterozygote advantage on the fitness scale. The reduction in phenotypic variance indicated that the populations with stablizing selection became somewhat more buffered against environmental sources of variation over the course of the experiment.

Comparison of In-the-Ear and Over-the-Ear Hearing Aid Fittings

1986 ◽  
Vol 51 (4) ◽  
pp. 362-369 ◽  
Author(s):  
Donna M. Risberg ◽  
Robyn M. Cox
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Comparative Evaluation ◽  
Speech Intelligibility ◽  
Hearing Aid ◽  
Hearing Aid Fitting ◽  
The Difference ◽  
Functional Gain ◽  
The Relationship

A custom in-the-ear (ITE) hearing aid fitting was compared to two over-the-ear (OTE) hearing aid fittings for each of 9 subjects with mild to moderately severe hearing losses. Speech intelligibility via the three instruments was compared using the Speech Intelligibility Rating (SIR) test. The relationship between functional gain and coupler gain was compared for the ITE and the higher rated OTE instruments. The difference in input received at the microphone locations of the two types of hearing aids was measured for 10 different subjects and compared to the functional gain data. It was concluded that (a) for persons with mild to moderately severe hearing losses, appropriately adjusted custom ITE fittings typically yield speech intelligibility that is equal to the better OTE fitting identified in a comparative evaluation; and (b) gain prescriptions for ITE hearing aids should be adjusted to account for the high-frequency emphasis associated with in-the-concha microphone placement.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

Reliability of a Single β-Thromboglobulin Measurement in a Diabetic Population : Importance of PGE1 in Anticoagulant Mixture

1987 ◽  
Vol 57 (02) ◽  
pp. 201-204 ◽  
Author(s):  
P Y Scarabin ◽  
L Strain ◽  
C A Ludlam ◽  
J Jones ◽  
E M Kohner
Keyword(s):  
In Vitro Release ◽  
Mean Value ◽  
Reliable Estimate ◽  
Diabetic Patients ◽  
Single Measurement ◽  
Diabetic Population ◽  
The Difference ◽  
Vitro Release

SummaryDuring the collection of samples for plasma β-thromboglobulin (β-TG) determination, it is well established that artificially high values can be observed due to in-vitro release. To estimate the reliability of a single β-TG measurement, blood samples were collected simultaneously from both arms on two separate occasions in 56 diabetic patients selected for a clinical trial. From each arm, blood was taken into two tubes containing an anticoagulant mixture with (tube A) and without (tube B) PGE!. The overall mean value of B-TG in tube B was 1.14 times higher than in tube A (p <0.01). The markedly large between-arms variation accounted for the most part of within-subject variation in both tubes and was significantly greater in tube B than in tube A. Based on the difference between B-TG values from both arms, the number of subjects with artifically high B-TG values was significantly higher in tube B than in tube A on each occasion (overall rate: 28% and 14% respectively). Estimate of between-occasions variation showed that B-TG levels were relatively stable for each subject between two occasions in each tube. It is concluded that the use of PGEi decreases falsely high B-TG levels, but a single measurement of B-TG does not provide a reliable estimate of the true B-TG value in vivo.

Klein with Lacan: A Study on the Reception of Lacanian Ideas in Uruguay and Its Effects on Clinical Practices (1955–82)

2020 ◽  
Vol 22 (3) ◽  
pp. 341-361
Author(s):  
Gonzalo Grau-Pérez ◽  
J. Guillermo Milán
Keyword(s):  
Clinical Practice ◽  
Clinical Material ◽  
Clinical Practices ◽  
Before And After ◽  
The Difference ◽  
The 1960S ◽  
The Relationship ◽  
Discursive Approach ◽  
The Way ◽  
Clinical Cases

In Uruguay, Lacanian ideas arrived in the 1960s, into a context of Kleinian hegemony. Adopting a discursive approach, this study researched the initial reception of these ideas and its effects on clinical practices. We gathered a corpus of discursive data from clinical cases and theoretical-doctrinal articles (from the 1960s, 1970s and 1980s). In order to examine the effects of Lacanian ideas, we analysed the difference in the way of interpreting the clinical material before and after Lacan's reception. The results of this research illuminate some epistemological problems of psychoanalysis, especially the relationship between theory and clinical practice.

The End of the Word as We Know It

2012 ◽  
Vol 6 (1-3) ◽  
pp. 165-184
Author(s):  
Timothy Beal
Keyword(s):  
Cultural Meanings ◽  
Cultural Icon ◽  
The Bible ◽  
Material Objectivity ◽  
The Difference ◽  
The Relationship

This essay attends to a distinction that requires closer examination and theorization in our discourse on iconic books and other scriptures: the difference between iconic object and cultural icon. How do we conceive of relations between the particular, ritualized iconicities of particular scriptures in particular religious contexts and the cultural iconicities of scriptures in general, such as “the Bible” or “the Quran,” whose visual and material objectivity is highly ambiguous? How if at all are the iconic cultural meanings of the ideas of such books related to the particular iconic textual objects more or less instantiate them? These questions are explored through particular focus on the relationship between the particular iconicities of particular print Bibles, as iconic objects, and the general iconicity of the cultural icon of the Bible.

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