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Search Results: 1 - 10 of 10254 matches for " gene frequencies "
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Métodos de estima??o do coeficiente de endogamia em uma popula??o diplóide com alelos múltiplos
Muniz, Joel Augusto;Camargo, Mariele Santana;Ferreira, Daniel Furtado;Veiga, Ruben Delly;
Ciência e Agrotecnologia , 2008, DOI: 10.1590/S1413-70542008000100014
Abstract: the present work evaluted the properties of three estimators of the inbreeding coefficient, f, in a diploid population with multiple alleles, using data of gene frequencies in individuals from random samples, obtained in simulate populations, through the sas. were evaluted the estimator of f, obtained by single and joint univariate analysis and the estimator of f obtained by multivariate analysis as proposed by long (1986). the analysis of the means and variances of the estimators, obtained of 1000 estimates of f, calculated for each sample size, it demonstrated that the three estimators is bias. however, it was observed that the estimator obtained of univariate analysis it was less biased and it presented smaller variance, when the inbreeding coefficient in the population was elevated, while for populations with low inbreeding, the variance of, the estimator obtained by the multivariate analysis it was smaller.
Biochemical and molecular investigations on qualitative and quantitative Hb polymorphism in the river buffalo (Bubalus bubalis L.) population reared in Southern Italy
Iorio, Mario;Vincenti, Donatella;Annunziata, Mario;Rullo, Rosario;Bonamassa, Raffaele;Di Luccia, Aldo;Pieragostini, Elisa;
Genetics and Molecular Biology , 2004, DOI: 10.1590/S1415-47572004000200007
Abstract: on 398 river buffalo samples, randomly collected in distinct breeding areas of the campania region, high-resolution analytical systems were used to identify both qualitative and quantitative variations of the hb phenotype. polyacrylamide gel isoelectric focusing and hplc were used to determine the ratio between hba1 and hba2 globin chains; restriction endonuclease analysis was performed to assess whether quantitative variations in hb bands were related to an unusual number of a-globin genes. in the two buffalo subpopulations, allele frequencies of the alpha and beta globin systems were calculated, and f statistics (fis, fit and fst) were estimated as parameters of genetic diversity. the results suggest that: i) as shown by rflp analysis, only a couple of associated a globin genes account for the quantitative variations recorded at the phenotypic level; ii) as expected, in the a globin gene system (hba), the frequency of haplotype b (hba-b) largely exceeded that of haplotype a (hba-a) (95.1% vs 4.9%); iii) the frequency of the usual allele at the beta locus is 0.6, as opposed to 0.4 of the slow variant; iiii) the most significant component of variation of the genetic system of hemoglobin is between individuals within the same location.
Genetic polymorphism of the αs1-casein locus in five populations of goats from Mexico
Torres-Vázquez,José Antonio; Vázquez Flores,Felícitas; Montaldo,Hugo H; Ulloa-Arvizu,Raúl; Valencia Posadas,Mauricio; Gayosso Vázquez,Amanda; Alonso Morales,Rogelio Alejandro;
Electronic Journal of Biotechnology , 2008,
Abstract: with the objective of estimating allele frequencies, and testing for population divergence for the csn1s1 locus, genotypes of animals from five goat populations; saanen (n = 97), alpine (n = 81) toggenburg (n = 92), local goats with external appearance similar to the murciana-granadina breed from central mexico (n = 26) and heterogeneous local animals denominated mosaico lagunero (n = 30), from northern mexico, were identified using pcr and xmn1 pcr-rflp methodology. for saanen, alpine and toggenburg, the sum of e and f alleles had the largest frequencies (from 0.468 to 0.789), while for the groups local murciana-granadina and mosaico lagunero the sum of the most frequent allelic groups (a* and b*), were 0.385 and 0.533 respectively. both local murciana-granadina and mosaico lagunero populations showed heterozygote excess (p < 0.08). the percentage of the total genetic variation (fst) explained by population differences was 5.16. there was genetic differentiation for most pair comparisons between populations (p < 0.05), excepting for alpine versus toggenburg, and toggenburg versus mosaico lagunero (p > 0.05). for saanen and alpine the frequencies of alleles e and f were similar to the same breeds previously analyzed in europe. therefore there are opportunities of increasing the frequency of the strong alleles for protein content gene assisted selection (gas) in these two breeds. for toggenburg the most frequent allelic groups were f (0.32) and b* (0.21). results indicate differentiation between most populations for this locus. moreover, heterozygote excess in local populations indicated breed admixture.
Determinación del polimorfismo C677T de metilentetrahidrofolato reductasa (MTHFR) en una población piloto de estudiantes de la Universidad del Rosario
González-Galofre,Zaniah N.; Villegas,Victoria; Martínez-Agüero,María;
Revista Ciencias de la Salud , 2010,
Abstract: introduction: the 5, 10-methylenetetrahydrofolate reductase (mthfr) is an essential enzyme in folate metabolism; their polymorphisms have been associated with heart disease risk increase, obstetric problems, neural tube defects in fetuses and cancer susceptibility. this gene has a single nucleotide polymorphism, a c-t change at nucleotide 677, which affects significantly its enzymatic activity. objective: because of the biological importance of this enzyme and the colombian population genetic heterogeneity characteristic, a study was performed to determine allele and genotype frequencies of mthfr c677t polymorphism in healthy individuals, taking into account that in colombia there are only studies that have involved case-control methodology. methods: we analyzed this polymorphism trough the amplification of the dna of a 206 students sample population. additionally, colombian overall frequencies were calculated, using data from healthy controls reported in other studies. results: a hardy-weinberg disequilibrium was found in the sample tested. for the colombian data, we found that the global population was in equilibrium. conclusion: t allele population frequency seems to be under positive selection pressure, which is reflected in the population allele increase, despite its deleterious effect. a spanish study reported similar results and identified folic acid supplementation on expectant mothers as a probably cause of this change.
The Gene Frequencies of 8 Genetic Traits in 4 Populations of Xinjiang
新疆四个民族八对遗传性状的基因频率 The Gene Frequencies of 8 Genetic Tratis in 4 Populations of Xinjiang

阿不都拉·巴克,依米提·热合曼,木合塔尔·阿不都克里木,哈斯亚提,吾甫尔·依明,阿帕尔·吾甫尔,阿帕尔·加帕尔,米娜瓦尔,吾期库阿依,拉孜古力,热孜亚Abdula Bakhy,Imit Rahman,Muhtar Abdukerim,Hasiyat,Gupur Imin,Gapar Gupur,Gapar Japar,Munawar,Uqkunay,Razigul Raziya
遗传 , 1997,
Abstract: 在调查新疆维吾尔、哈萨克、柯尔克孜、塔吉克族8对遗传性状的基础上分别计算出8对遗传性状在上述4个民族中的基因频率,并进行了4个民族之间基因频率的比较。比较结果表明:塔吉克与其他3个民族之间基因频率的差异显著,而哈族与柯族之间的差异不显著。
Determinación del polimorfismo C677T de metilentetrahidrofolato reductasa (MTHFR) en una población piloto de estudiantes de la Universidad del Rosario
Zaniah N. González-Galofre,Victoria Villegas,María Martínez-Agüero
Revista Ciencias de la Salud , 2010,
Abstract: Introduction: the 5, 10-methylenetetrahydrofolate reductase (MTHFR) is an essential enzyme in folate metabolism; their polymorphisms have been associated with heart disease risk increase, obstetric problems,neural tube defects in fetuses and cancer susceptibility. This genehas a single nucleotide polymorphism, a C-T change at nucleotide 677, which affects significantly its enzymatic activity. Objective: because of the biological importance of this enzyme and the Colombian population genetic heterogeneity characteristic, a study was performed to determine allele and genotype frequencies of MTHFR C677Tpolymorphism in healthy individuals, taking into account that in Colombia there are only studies that have involved casecontrol methodology. Methods: we analyzed this polymorphism trough the amplification of the DNA of a 206 students sample population.Additionally, Colombian overall frequencies were calculated, usingdata from healthy controls reported in other studies. Results: aHardy-Weinberg disequilibrium was found in the sample tested. For theColombian data, we found that the global population was in equilibrium. Conclusion: T allele population frequency seems to beunder positive selection pressure, which is reflected inthe population allele increase, despite its deleterious effect. ASpanish study reported similar results and identified folic acidsupplementation on expectant mothers as a probably cause of thischange.
Study the Thermal Gradient Effect on Frequencies of a Trapezoidal Plate of Linearly Varying Thickness  [PDF]
Arun Kumar Gupta, Pragati Sharma
Applied Mathematics (AM) , 2010, DOI: 10.4236/am.2010.15047
Abstract: In this paper, effect of thermal gradient on vibration of trapezoidal plate of varying thickness is studied. Thermal effect and thickness variation is taken as linearly in x-direction. Rayleigh Ritz technique is used to calculate the fundamental frequencies. The frequencies corresponding to the first two modes of vibrations are obtained for a trapezoidal plate for different values of taper constant, thermal gradient and aspect ratio. Results are presented in graphical form.
Generation and Propagation of Ultrasonic Waves in Piezoelectric Graphene Nanoribbon  [PDF]
Musah Rabiu, Samuel Y. Mensah, Sulemana S. Abukari, Matthew Amekpewu, Baah Sefa-Ntiri, Anthony Twum
Open Journal of Acoustics (OJA) , 2013, DOI: 10.4236/oja.2013.33A007
Abstract:

Generation and propagation of ultrasonic waves in single layer Graphene Nanoribbon is studied using semi-classical approach. When piezoelectric Graphene Nanoribbon (GNR) is exposed to time varying light beam, ultrasonic waves are produced which propagate in the medium. At low frequencies, we observed oscillations of the ultrasonic observables, velocity change and attenuation which are characteristics of massless Dirac fermions in graphene. Exploiting this oscillatory behavior, we estimate graphenes electronic mobility to be around . Propagating ultrasonic waves can be amplified, depending on the electric field amplitude. Specifically, amplification occurs when drift velocity exceeds sound velocity. This scheme can be employed for efficient ultrasonic amplifier device operation.

Finite One-Dimensional Photonic Crystal with Gaussian Modulation: Transmission and Escape  [PDF]
María de la Luz Silba-Vélez, David-Armando Contreras-Solorio, Rolando Pérez-álvarez, Carlos Iván Cabrera
Optics and Photonics Journal (OPJ) , 2017, DOI: 10.4236/opj.2017.710017
Abstract: This paper studied the transmission coefficient and escape frequencies in a system of planar dielectric layers where the refractive index changes from one layer to another through a Gaussian function. The wave equation with normal incidence is analyzed. For the calculations, the transfer matrix formalism is used. In a previous work, the transmission and escape problem for Gaussian electronic superlattices is investigated. Now it studied the electromagnetic modes for a system formed by layers where the refractive index of the structure is modulated by a Gaussian function. The system presents transparency bands of transmission and gaps without transmission. The escape frequencies \"\" are situated near these transparency bands but they do not coincide with them. is the frequency (mode) and Γ describes the width of the states. For these systems, the escape states are very wide. A non Gaussian system presents resonance peaks in the transmission and the escape states are narrow. The formation of transparency bands in the transmission for a Gaussian system is attributed to the widening of the escape states.
Supraliminal but No Subliminal Priming by High-Spatial Frequency Faces in a Face-Sex Discrimination Task  [PDF]
Shah Khalid, Ulrich Ansorge, Matthew Finkbeiner
Psychology (PSYCH) , 2015, DOI: 10.4236/psych.2015.612146
Abstract: It has been argued that visual subliminal processing of face-inherent sex information might depend on the retino-collicular projection. In the current study, we tested this possibility. Based on the known exclusive sensitivity of the retino-collicular projection for low spatial frequencies (LSF), we derived the following predictions. First, masked and, therefore, subliminal high-spatial frequency (HSF) face primes would not be processed, but, secondly, masked unfiltered face primes, thirdly, masked LSF face primes, and, fourthly, unmasked HSF primes should be processed and should lead to a congruence effect—that is, faster responses (better performance) in congruent conditions, with face primes and face targets of the same sex, as compared to incongruent conditions, with face primes and face targets of different sexes. These predictions were borne out in altogether three experiments. In Experiment 1, we observed that masked unfiltered primes created a congruence effect and that masked HSF primes failed to do so. In Experiment 2, we found that masked unfiltered primes and masked LSF primes both created significant congruence effects of about the same size. Finally, in Experiment 3, we demonstrated that unmasked HSF primes led to a congruence effect, whereas masked HSF primes failed to do so. Also, masking led to the subliminal presentation of the primes, as indicated by the fact that our participants were unaware of the masked but not the unmasked face primes. Together, these findings are in general agreement with an assumed origin of subliminal (or unaware) face processing along the magno-cellular projection of the human visual system.
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