Semiconservative Replication in the Quasispecies Model

This paper extends Eigen's quasispecies equations to account for the semiconservative nature of DNA replication. We solve the equations in the limit of infinite sequence length for the simplest case of a static, sharply peaked fitness landscape. We show that the error catastrophe occurs when $\mu$, the product of sequence length and per base pair mismatch probability, exceeds $2 \ln \frac{2}{1 + 1/k}$, where $k > 1$ is the first order growth rate constant of the viable ``master'' sequence (with all other sequences having a first-order growth rate constant of $1$). This is in contrast to the result of $\ln k$ for conservative replication. In particular, as $k \to \infty$, the error catastrophe is never reached for conservative replication, while for semiconservative replication the critical $\mu$ approaches $2 \ln 2$. Semiconservative replication is therefore considerably less robust than conservative replication to the effect of replication errors. We also show that the mean equilibrium fitness of a semiconservatively replicating system is given by $k (2 e^{-\mu/2} - 1)$ below the error catastrophe, in contrast to the standard result of $k e^{-\mu}$ for conservative replication (derived by Kimura and Maruyama in 1966).Comment: 15 pages, 7 figures, to be submitted to Phys. Rev.

Benefits of participation in Tennessee 4-H junior high academic conference as perceived by selected former participants

The purpose of this study was to determine if and how youth participating in Tennessee 4-H Junior High Academic Conference benefitted from attending the conference. Objectives of the study were to: (1) develop a demographic profile/description of survey respondents; (2) determine if participation in the conference influenced respondents to continue their education or get some idea of a field of study for the future, (3) to determine what perceived effect the conference had on respondents\u27 personal/social competencies, (4) to determine what perceived effect attending the conference had on respondents\u27 cognitive/creative competencies, (5) to determine what perceived effect attending the conference had on respondents\u27 vocational competence, (6) to determine what participants remembered most about the conference and (7) to gain any suggestions that participants had related to improving the conference in future years. A mailed questionnaire was developed to meet the objectives of the study. A random sample of the population was used for the mailing list and appropriate descriptive statistics were used in reporting findings. FINDINGS Respondents felt that the conference positively effected their knowledge of possible areas of study and steps needed to make career choices, their decision to continue their education and to a lesser degree their choice of main area(s) of study. Respondents were very positive in their responses to the effect of the conference on personal/social skills with the effect on interpersonal skills being the highest, effect on coping skills being next, followed by effect on judgement skills and finally by the effect on intrapersonal skills. Respondents were very positive about the effects of the conference on their cognitive/creative competencies with broadening their subject matter base of knowledge related to their project area being the highest, followed closely by effect on ability to leam/interest in learning, then effect on oral and written communication skills and effect on problem solving and analytical skills being last. Respondents were very positive about the effects of the conference on their vocational competencies with broadening understanding/awareness of vocational/job options being the highest followed by the effect on preparing necessary steps to choose a career. CONCLUSIONS Tennessee Junior High 4-H Academic Conference has a positive impact on participants. Participants increase their personal/social, cognitive/creative and vocational competencies by attending the conference. The conference has a positive impact on participants\u27 decisions to continue their education and the percentage of survey respondents majoring in agriculture was substantially larger than in the average population

Prevalence of Active School Transportation in the Upper East and Upper West Regions of Ghana

The use of active transportation such as walking to and from school is on the decline globally. The primary purpose of the study was to determine the prevalence of active school transportation among primary and junior high school students in the Upper East and Upper West regions of Ghana. The secondary purpose was to examine predictors for meeting the recommended daily number of steps. A total of 2505 (1117 boys and 1388 girls) primary (1583) and junior high school (922) students participated in the study. The distances from children\u27s homes to their schools, heights, and body weights were measured –their heights were used to estimate their stride lengths. The step count for each participant to and from school each day was calculated. Data were analyzed using conditional percentage distribution and Logit model. Analyses indicated that 98.96% of participants used active transportation to and from school. Over 63% of the students were within the normal BMI range. However, 26.47% of the participants were either thin or underweight while 9.9% were either overweight or obese. Overall, 46.47% of the participants met the recommended daily steps. The Logit model indicated that educational level, BMI, mode of transportation, region, height, and age were significant predictors for meeting the recommended daily number of steps. The prevalence of school active transportation in the present study was high compared to that reported in other studies. Furthermore, the prevalence of thinness and underweight were higher than in previous studies, while the prevalence in overweight and obesity were lower

Regulatory network reconstruction using an integral additive model with flexible kernel functions

<p>Abstract</p> <p>Background</p> <p>Reconstruction of regulatory networks is one of the most challenging tasks of systems biology. A limited amount of experimental data and little prior knowledge make the problem difficult to solve. Although models that are currently used for inferring regulatory networks are sometimes able to make useful predictions about the structures and mechanisms of molecular interactions, there is still a strong demand to develop increasingly universal and accurate approaches for network reconstruction.</p> <p>Results</p> <p>The additive regulation model is represented by a set of differential equations and is frequently used for network inference from time series data. Here we generalize this model by converting differential equations into integral equations with adjustable kernel functions. These kernel functions can be selected based on prior knowledge or defined through iterative improvement in data analysis. This makes the integral model very flexible and thus capable of covering a broad range of biological systems more adequately and specifically than previous models.</p> <p>Conclusion</p> <p>We reconstructed network structures from artificial and real experimental data using differential and integral inference models. The artificial data were simulated using mathematical models implemented in JDesigner. The real data were publicly available yeast cell cycle microarray time series. The integral model outperformed the differential one for all cases. In the integral model, we tested the zero-degree polynomial and single exponential kernels. Further improvements could be expected if the kernel were selected more specifically depending on the system.</p

Time- and Space-Efficient Evaluation of Some Hypergeometric Constants

The currently best known algorithms for the numerical evaluation of hypergeometric constants such as $\zeta(3)$ to $d$ decimal digits have time complexity $O(M(d) \log^2 d)$ and space complexity of $O(d \log d)$ or $O(d)$. Following work from Cheng, Gergel, Kim and Zima, we present a new algorithm with the same asymptotic complexity, but more efficient in practice. Our implementation of this algorithm improves slightly over existing programs for the computation of $\pi$, and we announce a new record of 2 billion digits for $\zeta(3)$

Ghanaian Classroom Teacher Trainees’ Perceived Competence and Intrinsic Motivation in Physical Education

Primary school teachers in Ghana are non-specialists but are required to teach physical education (PE) in addition to the regular subjects taught in primary classrooms (CS). Using a Self-Determination Theory, this study examined classroom teacher trainees’ (TT) perceived competence and intrinsic motivation in learning to teach PE. In addition, the study compared TTs’ competence and motivation in PE and CS. Participants included a purposive sample of 190 from two colleges of education in Ghana. They completed modified forms of the Perceived Competence Scale (PCS) and the Intrinsic Motivation (IM) subscale of the Perceived Locus of Causality once. Descriptive statistics showed most TTs had moderate to high levels of competence and intrinsic motivation both in PE and CS. Independent Samples t-Test and One-Way ANOVA analyses indicated significant gender and grade level differences for PCS in PE. A Paired-Samples t-Test analysis indicated TTs’ PCS mean score was significantly higher in CS than that in PE. However, TTs’ motivation in PE and CS were similar. The classroom teacher trainees in this study perceived themselves to be less competent in PE than in non-PE contents (CS), even though their levels of motivation to learn to teach in both contexts were similar. This is consistent with extant literature that teachers in Ghanaian primary schools are not adequately prepared to teach PE. The development of children’s PE programs in the country’s teacher education institutions is warranted