| 1. |
- Natiello, Mario, et al.
(författare)
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A Braided View of a Knotty Story
- 2013
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Ingår i: Topology and Dynamics of Chaos. - : WORLD SCIENTIFIC. - 9789814434850 - 9789814434874 ; , s. 149-168
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Bokkapitel (refereegranskat)abstract
- Periodic orbits of 3-d dynamical systems admitting a Poincaré section can be described as braids. This characterisation can be transported to the Poincaré section and Poincaré map, resulting in the braid type. Information from braid types allows to estimate bounds for the topological entropy of the map while revealing detailed orbit information from the original system, such as the orbits that are necessarily present along with the given one(s) and their organisation. We review this characterisation with some examples --from a user-friendly perspective--, focusing on systems whose Poincaré section is homotopic to a disc.
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| 2. |
- Natiello, Mario A., et al.
(författare)
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Modelling population dynamics based on experimental trials with genetically modified (RIDL) mosquitoes
- 2020
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800. ; 424
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Tidskriftsartikel (refereegranskat)abstract
- Recently, the RIDL-SIT technology has been field-tested for control of Aedes aegypti. The technique consists of releasing genetically modified mosquitoes carrying a “lethal gene”. In 2016 the World Health Organization (WHO) and the Pan-American Health Organization (PAHO) recommended to their constituent countries to test the new technologies proposed to control Aedes aegypti populations. However, issues concerning effectiveness and ecological impact have not been thoroughly studied so far. In order to study these issues, we develop an ecological model. It presents interdependent dynamics of mosquito populations and food in a homogeneous setting. Mosquito populations are described in a stochastic compartmental setup, in terms of reaction norms depending on the available food in the environment. The development of the model allows us to indicate some critical biological knowledge that is missing and could (should) be produced. Hybridisation levels, release numbers during and after intervention and population recovery time after the intervention as a function of intervention duration and target are calculated under different hypotheses with regard to the fitness of hybrids and compared with two field studies of actual interventions. This minimal model should serve as a basis for detailed models when the necessary information to construct them is produced. For the time being, the model shows that nature will not clean non-lethal introgressed genes.
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| 3. |
- Natiello, Mario, et al.
(författare)
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Blowing-up of deterministic fixed points in stochastic population dynamics
- 2007
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Ingår i: Mathematical Biosciences. - : Elsevier BV. - 0025-5564. ; 209:2, s. 319-335
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the stochastic dynamics of biological (and other) populations presenting a limit behaviour for large environments (called deterministic limit) and its relation with the dynamics in the limit. The discussion is circumscribed to linearly stable fixed points of the deterministic dynamics, and it is shown that the cases of extinction and non-extinction equilibriums present different features. Mainly, non-extinction equilibria have associated a region of stochastic instability surrounded by a region of stochastic stability. The instability region does not exist in the case of extinction fixed points, and a linear Lyapunov function can be associated with them. Stochastically sustained oscillations of two subpopulations are also discussed in the case of complex eigenvalues of the stability matrix of the deterministic system. (C) 2007 Elsevier.Inc. All rights reserved.
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| 4. |
- Natiello, Mario, et al.
(författare)
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Multinomial approximation to the Kolmogorov Forward Equation for jump (population) processes
- 2018
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Ingår i: Cogent mathematics and Statistics. - : Informa UK Limited. - 2574-2558.
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Tidskriftsartikel (refereegranskat)abstract
- We develop a simulation method for Markov Jump processes with finite time steps based in a quasilinear approximation of the process and in multinomial random deviates. The second order approximation to the generating function, Error$=O(dt^{2})$, is developed in detailand an algorithm is presented. The algorithm is implemented for a Susceptible-Infected-Recovered-Susceptible (SIRS) epidemic model and compared to both the deterministic approximation and the exact simulation. Special attention is given to the problem of extinction of the infected population which is the most critical condition for the approximation.
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| 5. |
- Natiello, Mario, et al.
(författare)
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On the Removal of Infinities from Divergent Series
- 2015
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Ingår i: Philosophy of Mathematics Education Journal. - 1465-2978. ; 29, s. 13-13
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Tidskriftsartikel (refereegranskat)abstract
- The consequences of adopting other definitions of the concepts of sum and convergence of a series are discussed in the light of historical and epistemological contexts. We show that some divergent series appearing in the context of renormalization methods cannot be assigned finite values while preserving a minimum of consistency with standard summation, without at the same time obtaining contradictions, thus destroying the mathematical building (the conditions are known as Hardy’s axioms). We finally discuss the epistemological costs of accepting these practices in the name of instrumentalism.
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| 6. |
- Natiello, Mario, et al.
(författare)
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The construction of Electromagnetism
- 2019
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Ingår i: PhilArchive - Western University - Canada.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We examine the construction of electromagnetism in its current form, and in an alternative form, from a point of view that combines a minimal realism with strict rational demands. We begin by discussing the requests of reason when constructing a theory and next, we follow the historical development as presented in the record of original publications, the underlying epistemology (often explained by the authors) and the mathematical constructions. The historical construction develops along socio-political disputes (mainly, the reunification of Germany and the second industrial revolution), epistemic disputes (at least two demarcations of science in conflict) and several theories of electromagnetism. Such disputes resulted in the militant adoption of the ether by some, a position that expanded in parallel with the expansion of Prussia. This way of thinking was facilitated by the earlier adoption of a standpoint that required, as a condition for understanding, the use of physical hypothesis in the form of analogies; an attitude that is antithetic to Newton's “hypotheses non fingo”. While the material ether was finally abandoned, the epistemology survived in the form of “substantialism” and a metaphysical ether: the space. The militants of the ether attributed certainties regarding the ether to Faraday and Maxwell, when they only expressed doubts and curiosity. Thus, the official story is not the real history. This was achieved by the operation of detaching Maxwell's electromagnetism from its construction and introducing a new game of formulae and interpretations. Large and important parts of Maxwell work are today not known, as for example, the rules for the transformation of the electromagnetic potentials between moving systems. When experiments showed that all the theories based in the material ether were incorrect, a new interpretation was offered: Special Relativity (SR). At the end of the transformation period a pragmatic view of science, well adapted to the industrial society, had emerged, as well as a new protagonist: the theoretical physicist. The rival theory of delayed action at distance initiated under the influence of Gauss was forgotten in the midst of the intellectual warfare. The theory is indistinguishable in formulae from Maxwell's and its earlier versions are the departing point of Maxwell for the construction of his equations. We show in a mathematical appendix that such (relational) theory can incorporate Lorentz' contributions as well as Maxwell's transformations and C. Neumann's action, without resource to the ether. Demarcation criteria was further changed at the end of the period making room for habits and intuitions. When these intuited criteria are examined by critical reason (seeking for the fundaments) they can be sharpened with the use of the Non Arbitrariness Principle, which throws light over the arbitrariness in the construction of SR. Under a fully rational view SR is not acceptable, it requires to adopt a less demanding epistemology that detaches the concept from the conception, such as Einstein's own view in this respect, inherited from Hertz. In conclusion: we have shown in this relevant exercise how the reality we accept depends on earlier, irrational, decisions that are not offered for examination but rather are inherited from the culture.
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| 7. |
- Otero, Marcelo, et al.
(författare)
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Modeling dengue outbreaks
- 2011
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Ingår i: Mathematical Biosciences. - : Elsevier BV. - 0025-5564. ; 232:2, s. 87-95
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a dengue model (SEIR) where the human individuals are treated on an individual basis (IBM) while the mosquito population, produced by an independent model, is treated by compartments (SEI). We study the spread of epidemics by the sole action of the mosquito. Exponential, deterministic and experimental distributions for the (human) exposed period are considered in two weather scenarios, one corresponding to temperate climate and the other to tropical climate. Virus circulation, final epidemic size and duration of outbreaks are considered showing that the results present little sensitivity to the statistics followed by the exposed period provided the median of the distributions are in coincidence. Only the time between an introduced (imported) case and the appearance of the first symptomatic secondary case is sensitive to this distribution. We finally show that the IBM model introduced is precisely a realization of a compartmental model, and that at least in this case, the choice between compartmental models or IBM is only a matter of convenience. (C) 2011 Elsevier Inc. All rights reserved.
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| 8. |
- Romeo Aznar, Victoria, et al.
(författare)
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A model for the development of Aedes (Stegomyia) aegypti as a function of the available food
- 2015
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Ingår i: Journal of Theoretical Biology. - : Elsevier BV. - 1095-8541 .- 0022-5193. ; 365, s. 311-324
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the preimaginal development of the mosquito Aedes aegypti from the point of view of the statistics of developmental times and the final body-size of the pupae and adults. We begin the discussion studying existing models in relation to published data for the mosquito. The data suggest a developmental process that is described by exponentially distributed random times. The existing data show as well that the idea of cohorts emerging synchronously is verified only in optimal situations created at the laboratory but it is not verified in field experiments. We propose a model in which immature individuals progress in successive stages, all of them with exponentially distributed times, according to two different rates (one food-dependent and the other food-independent). This phenomenological model, coupled with a general model for growing, can explain the existing observations and new results produced in this work. The emerging picture is that the development of the larvae proceeds through a sequence of steps. Some of the steps depend on the available food. While food is in abundance, all steps can be thought as having equal duration, but when food is scarce, those steps that depend on food take considerably longer times. For insufficient levels of food, increase in larval mortality sets in. As a consequence of the smaller rates, the average pupation time increases and the cohort disperses in time. Dispersion, as measured by standard deviation, becomes a quadratic function of the average time indicating that cohort dispersion responds to the same causes than delays in pupation and adult emergence. During the whole developmental process the larva grows monotonically, initially at an exponential rate but later at decreasing rates, approaching a final body-size. Growth is stopped by maturation when it is already slow. As a consequence of this process, there is a slight bias favoring small individuals: Small individuals are born before larger individuals, although the tendency is very weak.
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| 9. |
- Romero Fernández, Alejandro, et al.
(författare)
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¿Crisis de la ciencia o crisis civilizatoria?
- 2018
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Ingår i: Crisis de mundo: Perspectivas filosóficas (preliminar title). - 9789875749870
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- En este trabajo planteamos cuales son las formas particulares que toma en ciencia la crisis de la civilización. Formas que no siempre son fáciles de advertir. Crisis de la ciencia que es causa y consecuencia de la crisis civilizatoria. Partimos de observaciones realizadas dentro del campo científico que indican un fuerte retroceso de la razón crítica en ciencia quedando vigente solamente la razón instrumental y en ocasiones menos aún: un empirismo sin razón. Exponemos el proceso de extinción de la ciencia en su continua y activa metamorfosis como tecnociencia, próxima ya a emerger en la forma pura de tecnología. Es decir, el abandono del saber (episteme) por el saber hacer (techné). El abandono del ideal del cosmos o de la unidad de la razón por la noción de éxito como principio orientador de la labor de los pensadores. Señalamos asimismo las formas sociales por las que se reproduce la tecnociencia y la mutilación de la razón. Finalmente proponemos mínimas acciones para frenar o revertir este proceso.
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| 10. |
- Solari, Hernán G, et al.
(författare)
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La ciencia administrada
- 2016
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Ingår i: Sociología y Tecnociencia. - 1989-8487. ; 2:6, s. 30-55
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Tidskriftsartikel (refereegranskat)abstract
- A partir del fin de la Segunda Guerra Mundial se extiende, partiendo de los EEUU, una comprensión y uso de la ciencia subordinadas al proceso de producción. Esto determina el avance, sobre el campo científico, de un proceso de administración de la investigación y de la formación por parte del Estado y, a través de él, del aparato productivo. Esa subordinación de la actividad científica a la utilidad productiva promueve la extinción del pensamiento crítico en favor de un pensamiento puramente instrumental. Y con ello el sofocamiento de la crítica y la creación en favor de la explotación de la ciencia existente: la ciencia normal. En la formación, se pasa de una formación destina-da a cultivar la racionalidad y el examen crítico, valorando el conocimiento como un bien en sí mismo, a una formación destinada a promover la aceptación acrítica de la ciencia normal y su uso y “acrecentamiento” meramente profesionales, valorando el cono-cimiento sólo en la medida en que es útil desde el punto de vista mercantil o de segu-ridad. Todo ello, reproducido de modo casi coactivo por los métodos de evaluación y las políticas de publicación, que castigan a los investigadores críticos y creativos y premian sistemáticamente la repetición, el uso técnico y la subordinación instrumental a los paráme-tros de la ciencia normal. Estos mecanismos tienden a ampliar la reproducción de estos rasgos y a empujar a la extinción aquellos que no se ajustan a sus objetivos.An understanding and use of science subordinate to the production process extends worldwide, starting from USA around the end of World War II. This strategy determines the advance of a management process for research and training on the scientific field, operated by the National administrations and, through them, by the productive apparatus. Such subordination of scientific activity to productive use promotes the extinction of critical thinking in favor of a purely instrumental thinking and thus the suffocation of criticism and creativity in favor of the exploitation of existing science: normal science. In training, a shift takes place, from training designed to cultivate rationality and critical examination, valuing knowledge as a good in itself, to a training designed to promote the uncritical acceptance of normal science, its use and "enhancement" in a merely professional way, valuing knowledge only insofar as it is useful from a commercial or a security point of view. This shift is reproduced in an almost coercive manner by the methods of evaluation and the publishing policies that punish critic and creative researchers while systematically rewarding repetition, technical use and instrumental subordination to the parameters of normal science. This managing mechanism tends to enhance the reproduction of its traits and to push towards extinction those traits that fail to match its goals.
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