Quantifying metastatic inefficiency:rare genotypes versus rare dynamics

abstract: We 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.e. θ 1), i.e. the statistics show a duality mapping (1 − θ) → (θ − 1). We conclude our analysis with a study of heterogeneity in the fitness of colonising cells, and describe a phase diagram delineating parameter regions in which metastatic colonization is dominated either by low or high fitness cells, showing that both are plausible given our current knowledge of physiological conditions in human cancer

A formula for the trace of symmetric powers of matrices

We present a formula for the trace of any symmetric power of a $n\times n$ matrix (with coefficients in a field) in terms of the ordinary powers of the matrix, an arbitrarily chosen linear function which vanishes on the identity matrix, and $n-2$ polynomial functions defined recursively

Analysis of the impact of test based development techniques (TDD, BDD, AND ATDD) to the software life cycle

Within the world of software development, there is a permanent need to create quality products that are capable of facing challenges in environments of changing requirements. The industry in this area is aware of this, and so, it makes use of software development methodologies such as: traditional or agile. Agile development represents a distancing from traditional approaches, allowing the creation of applications incrementally and iteratively and, thus, adjusting to the changing requirements of customers. For this reason, companies have recently adopted the use of its practices and techniques, e.g.: Test-Driven Development (TDD), Acceptance Test-Driven Development (ATDD), Behavior-Driven Development (BDD), among others. These techniques promise mainly to improve the quality of the software and the productivity of the programmers; therefore, many experiments, especially using TDD, have been made within the academy and the industry; which shows variant results (some with positive effects and others not so much). In addition, expert programmers have put these techniques into practice in software creation, getting satisfactory results due to the advantages offered by its use. The main objective of this work is to verify the impact produced by the techniques of software development based on tests (TDD, ATDD and BDD), analyzing its primordial promises. A literature research has been conducted in order to understand the strengths and weaknesses of each one of these techniques. With the intention of observing the effectiveness of TDD and BDD, an experiment was planned in an academic scenario, considering education and appropriate training to implement enough knowledge about them. With the results obtained, it was possible to understand that the techniques studied ensured the quality of the product developed and improved the productivity of the programmers; validating its effects within software development

Concurs de projectes per a la redacció del projecte bàsic i executiu i la posterior direcció de les obres i coordinació de seguretat i salut, per a la construcció dels nous vestidors del camp d’esports municipal

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