There is ongoing debate regarding the culture of competitive women's sports. On one hand, women who participate in sports are viewed as adhering to and reinforcing heteronormative stereotypes and hegemonic masculinity. Conversely, women's sports are viewed as an inherently supportive environment for those involved.
View Article and Find Full Text PDFThe purpose of this article is three-fold: (1) revisit the concept of life skills to position physical literacy as a social justice life skill; (2) make the argument that physical literacy is particularly relevant within a critical positive youth development perspective; and (3) propose a novel critical praxis for developing physical literacy amongst youth. When considering emergent social issues, youth programming has the potential to integrate concepts from a range of theoretical frameworks, which may help youth transform into social change activists and competent movers. Such critical perspectives may guide sport and physical education programming as contemporary society poses numerous challenges concerning youths' diverse emotional, mental, physical, and social needs.
View Article and Find Full Text PDFIn order to maintain functional robustness and species integrity, organisms must ensure high fidelity of the genome duplication process. This is particularly true during early development, where cell division is often occurring both rapidly and coherently. By studying the extreme limits of suppressing DNA replication failure due to double fork stall errors, we uncover a fundamental constant that describes a trade-off between genome size and architectural complexity of the developing organism.
View Article and Find Full Text PDFPublic health advocates have been calling for an intensified focus on early, middle, and late adolescence health behaviours due to both the short- and long-term health consequences. Hence, both the health-risk (e.g.
View Article and Find Full Text PDFIntroduction: The purpose of this pilot study was to assess the effectiveness of the revised My Body Knows When (MBKW) program to promote intuitive eating behaviors within a sample of a military population through an online or in-person delivery mode.
Materials And Methods: Fifty-six overweight or obese adults (70% female); military service members (20%), retirees (38%) and family (42%) participated in the 10-week MBKW program at two military installations from 2012 to 2014. Body Mass Index, Intuitive Eating Scale-2 (IES-2; 23-item) and Motivation for Eating scale (MFES; 43-item) were collected at baseline and 10-weeks.
The parasitic African trypanosome, Trypanosoma brucei, evades the adaptive host immune response by a process of antigenic variation that involves the clonal switching of variant surface glycoproteins (VSGs). The VSGs that come to dominate in vivo during an infection are not entirely random, but display a hierarchical order. How this arises is not fully understood.
View Article and Find Full Text PDFFor many cancer types, incidence rises rapidly with age as an apparent power law, supporting the idea that cancer is caused by a gradual accumulation of genetic mutations. Similarly, the incidence of many infectious diseases strongly increases with age. Here, combining data from immunology and epidemiology, we show that many of these dramatic age-related increases in incidence can be modeled based on immune system decline, rather than mutation accumulation.
View Article and Find Full Text PDFUsing a combination of mathematical modelling, statistical simulation and large-scale data analysis we study the properties of linear regulatory chains (LRCs) within gene regulatory networks (GRNs). Our modelling indicates that downstream genes embedded within LRCs are highly insulated from the variation in expression of upstream genes, and thus LRCs act as attenuators. This observation implies a progressively weaker functionality of LRCs as their length increases.
View Article and Find Full Text PDFThe replication of DNA is initiated at particular sites on the genome called replication origins (ROs). Understanding the constraints that regulate the distribution of ROs across different organisms is fundamental for quantifying the degree of replication errors and their downstream consequences. Using a simple probabilistic model, we generate a set of predictions on the extreme sensitivity of error rates to the distribution of ROs, and how this distribution must therefore be tuned for genomes of vastly different sizes.
View Article and Find Full Text PDFTo prevent rereplication of genomic segments, the eukaryotic cell cycle is divided into two nonoverlapping phases. During late mitosis and G1 replication origins are "licensed" by loading MCM2-7 double hexamers and during S phase licensed replication origins activate to initiate bidirectional replication forks. Replication forks can stall irreversibly, and if two converging forks stall with no intervening licensed origin-a "double fork stall" (DFS)-replication cannot be completed by conventional means.
View Article and Find Full Text PDFWe discuss an overtly "simple approach" to complex biological systems borrowing selectively from theoretical physics. The approach is framed by three maxims, and we show examples of its success in two different applications: investigating cellular robustness at the level of gene regulatory networks and quantifying rare events of DNA replication errors.
View Article and Find Full Text PDFThe gene regulatory network (GRN) is the central decision-making module of the cell. We have developed a theory called Buffered Qualitative Stability (BQS) based on the hypothesis that GRNs are organised so that they remain robust in the face of unpredictable environmental and evolutionary changes. BQS makes strong and diverse predictions about the network features that allow stable responses under arbitrary perturbations, including the random addition of new connections.
View Article and Find Full Text PDFWe introduce and solve a 'null model' of stochastic metastatic colonization. The model is described by a single parameter θ: the ratio of the rate of cell division to the rate of cell death for a disseminated tumour cell in a given secondary tissue environment. We are primarily interested in the case in which colonizing cells are poorly adapted for proliferation in the local tissue environment, so that cell death is more likely than cell division, i.
View Article and Find Full Text PDFDuring S phase, the entire genome must be precisely duplicated, with no sections of DNA left unreplicated. Here, we develop a simple mathematical model to describe the probability of replication failing due to the irreversible stalling of replication forks. We show that the probability of complete genome replication is maximized if replication origins are evenly spaced, the largest inter-origin distances are minimized, and the end-most origins are positioned close to chromosome ends.
View Article and Find Full Text PDFGenetic feedback loops in cells break detailed balance and involve bimolecular reactions; hence, exact solutions revealing the nature of the stochastic fluctuations in these loops are lacking. We here consider the master equation for a gene regulatory feedback loop: a gene produces protein which then binds to the promoter of the same gene and regulates its expression. The protein degrades in its free and bound forms.
View Article and Find Full Text PDFComment on: Witkiewicz AK, et al. Cell Cycle 2012; 1108–1117
View Article and Find Full Text PDFPrimitive streak formation in the chick embryo involves significant coordinated cell movement lateral to the streak, in addition to the posterior-anterior movement of cells in the streak proper. Cells lateral to the streak are observed to undergo 'polonaise movements', i.e.
View Article and Find Full Text PDFCells and the tissues they form are not passive material bodies. Cells change their behavior in response to external biochemical and biomechanical cues. Behavioral changes, such as morphological deformation, proliferation and migration, are striking in many multicellular processes such as morphogenesis, wound healing and cancer progression.
View Article and Find Full Text PDFMeasurements on embryonic epithelial tissues in a diverse range of organisms have shown that the statistics of cell neighbor numbers are universal in tissues where cell proliferation is the primary cell activity. Highly simplified non-spatial models of proliferation are claimed to accurately reproduce these statistics. Using a systematic critical analysis, we show that non-spatial models are not capable of robustly describing the universal statistics observed in proliferating epithelia, indicating strong spatial correlations between cells.
View Article and Find Full Text PDFRecently, the Subcellular Element Model (SEM) has been introduced, primarily to compute the dynamics of large numbers of three-dimensional deformable cells in multicellular systems. Within this model framework, each cell is represented by a collection of elastically coupled elements, interacting with one another via short-range potentials, and dynamically updated using over-damped Langevin dynamics. The SEM can also be used to represent a single cell in more detail, by using a larger number of subcellular elements exclusively identified with that cell.
View Article and Find Full Text PDFThis paper is comprised of two parts. In the first we provide a brief overview of grid-free methods for modeling multicellular systems. We focus on an approach based on Langevin equations, in which inertia is ignored, and stochastic effects on cell motion are included.
View Article and Find Full Text PDFPopulation dynamics across a mortality gradient at an ecological margin are investigated using a novel modeling approach that allows direct comparison of stochastic spatially explicit simulation results with deterministic mean field models. The results show that demographic stochasticity has a large effect at population margins such that density profiles fall off more sharply than predicted by mean field models. Substantial spatial structure emerges at the margin, and spatial correlations (measured parallel to the margin) exhibit a sharp maximum in the tail of the density profile, indicating that spatial substructuring is greatest at an intermediate point across the ecological gradient.
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