implementaci?n de una secuencia de ense?anza - aprendizaje (SEA) en teor?a de evoluci?n biol?gica: aproximaci?n a la transformaci?n de las concepciones de naturaleza de la ciencia de profesores en formaci?n

164 p. Recurso Electr?nicoEste proyecto deriva de una propuesta anterior del grupo de investigaci?n en did?ctica de las ciencias, articul?ndose al amplio recorrido que en investigaci?n en concepciones de naturaleza de las ciencias este posee. La intenci?n inicial fue constituir una SEA (Secuencia de Ense?anza - Aprendizaje) aplicable a un grupo base de investigaci?n en concepciones de naturaleza de la ciencia (en adelante NdC), caso particular la teor?a de evoluci?n, con profesores en formaci?n del programa de Licenciatura en ciencias naturales y educaci?n ambiental, que indagara por las concepciones epistemol?gicas, hist?ricas y sociol?gicas que estos poseen respecto a la teor?a de evoluci?n biol?gica. Acto seguido se implement? la secuencia propuesta y se registraron las sesiones realizadas, para finalmente mediante an?lisis de contenido, buscar la informaci?n que permita evidenciar alg?n tipo de transformaci?n en las concepciones de naturaleza de la ciencia, para as?, acercarnos al logro de los prop?sitos planteados por el movimiento internacional CTS, tanto en la alfabetizaci?n cient?fica como en la formaci?n de una mejor ciudadan?a. De modo que identificadas las dificultades o principios en conflicto, lo que algunos autores han llamado concepciones inadecuadas de epistemolog?a, historia y sociolog?a de las ciencias. (Aikenhead, 2003; Cardoso, Morales y V?zquez, 2009; Cutrera, 2003; Erazo, 2009; Guisasola, 2000; Hern?ndez, 2009; Hodson, 1996; Izquierdo, 2000; Lederman, 1992; V?zquez, Acevedo, Mannassero y Acevedo, 2006), se proceder? a confrontarlos con las concepciones aceptadas de naturaleza de las ciencias en lo que respecta actualmente para la teor?a de evoluci?n biol?gica, de acuerdo a su quehacer, prop?sito, contexto y productos, todo dentro de un contexto de constante renovaci?n, justificaci?n, argumentaci?n, di?logo y aplicaci?n de nuevas propuestas did?cticas.This project stems from an earlier proposal of the research group on science education, articulating the broad path that research on conceptions of nature of science, this has. The initial intention was to be a SEA (sequence Teaching Learning) applicable to a core group of research on conceptions of nature of science (hereinafter NDC), particular case the theory of evolution with teachers in training the Bachelor program in natural sciences and environmental education, which investigates by the epistemological, historical and sociological that they possess regarding the concepts of the theory of biological evolution conceptions. Then the proposed sequence was implemented and the sessions were recorded, and finally through content analysis, seeking information that will uncover some transformation in conceptions of nature of science, enabling closer to achieving the aims set by the international movement CTS agencies such as UNESCO and the American Association for the Advancement of Science (AAAS) on the construction of a scientific culture, contribution to a democratic life and better citizenship. So the difficulties identified or conflicting principles, which some authors have called inadequate conceptions of philosophy, history and sociology of science. (Aikenhead, 2003; Cardoso, Morales and Vazquez, 2009; Cutrera, 2003; Erazo, 2009; Guisasola, 2000; Hernandez, 2009; Hodson, 1996; Izquierdo, 2000; Lederman, 1992; Vazquez, Acevedo, Mannassero and Acevedo, 2006 ), proceed to confront them with the accepted conceptions of nature of science in relation to current theory of biological evolution, according to their work, purpose, context and products. All within a context of constant renewal, justification, argumentation and application of new educational proposals. Keywords: Nature of Science (NDC), Theory of Evolution (TE), Epistemology, content analysis

Time boundary terms and Dirac constraints

Time boundary terms usually added to action principles are systematically handled in the framework of Dirac's canonical analysis. The procedure begins with the introduction of the boundary term into the integral Hamiltonian action and then the resulting action is interpreted as a Lagrangian one to which Dirac's method is applied. Once the general theory is developed, the current procedure is implemented and illustrated in various examples which are originally endowed with different types of constraints.Comment: 12 page

Plasticity of histamine H3 receptor expression and binding in the vestibular nuclei after labyrinthectomy in rat

Background: In rat, deafferentation of one labyrinth (unilateral labyrinthectomy) results in a characteristic syndrome of ocular and motor postural disorders (e.g., barrel rotation, circling behavior, and spontaneous nystagmus). Behavioral recovery (e.g., diminished symptoms), encompassing 1 week after unilateral labyrinthectomy, has been termed vestibular compensation. Evidence suggesting that the histamine H3 receptor plays a key role in vestibular compensation comes from studies indicating that betahistine, a histamine-like drug that acts as both a partial histamine H1 receptor agonist and an H3 receptor antagonist, can accelerate the process of vestibular compensation. Results: Expression levels for histamine H3 receptor (total) as well as three isoforms which display variable lengths of the third intracellular loop of the receptor were analyzed using in situ hybridization on brain sections containing the rat medial vestibular nucleus after unilateral labyrinthectomy. We compared these expression levels to H3 receptor binding densities. Total H3 receptor mRNA levels (detected by oligo probe H3X) as well as mRNA levels of the three receptor isoforms studied (detected by oligo probes H3A, H3B, and H3C) showed a pattern of increase, which was bilaterally significant at 24 h post-lesion for both H3X and H3C, followed by significant bilateral decreases in medial vestibular nuclei occurring 48 h (H3X and H3B) and 1 week post-lesion (H3A, H3B, and H3C). Expression levels of H3B was an exception to the forementioned pattern with significant decreases already detected at 24 h post-lesion. Coinciding with the decreasing trends in H3 receptor mRNA levels was an observed increase in H3 receptor binding densities occurring in the ipsilateral medial vestibular nuclei 48 h post-lesion. Conclusion: Progressive recovery of the resting discharge of the deafferentated medial vestibular nuclei neurons results in functional restoration of the static postural and occulomotor deficits, usually occurring within a time frame of 48 hours in rats. Our data suggests that the H3 receptor may be an essential part of pre-synaptic mechanisms required for reestablishing resting activities 48 h after unilateral labyrinthectomy

Quantum simulation of the Anderson Hamiltonian with an array of coupled nanoresonators: delocalization and thermalization effects

The possibility of using nanoelectromechanical systems as a simulation tool for quantum many-body effects is explored. It is demonstrated that an array of electrostatically coupled nanoresonators can effectively simulate the Bose-Hubbard model without interactions, corresponding in the single-phonon regime to the Anderson tight-binding model. Employing a density matrix formalism for the system coupled to a bosonic thermal bath, we study the interplay between disorder and thermalization, focusing on the delocalization process. It is found that the phonon population remains localized for a long time at low enough temperatures; with increasing temperatures the localization is rapidly lost due to thermal pumping of excitations into the array, producing in the equilibrium a fully thermalized system. Finally, we consider a possible experimental design to measure the phonon population in the array by means of a superconducting transmon qubit coupled to individual nanoresonators. We also consider the possibility of using the proposed quantum simulator for realizing continuous-time quantum walks.Comment: Replaced with new improved version. To appear in EPJ Q

The electrical double layer for a fully asymmetric electrolyte around a spherical colloid: an integral equation study

The hypernetted chain/mean spherical approximation (HNC/MSA) integral equation is obtained and solved numerically for a totally asymmetric primitive model electrolyte around a spherical macroparticle. The ensuing radial distribution functions show a very good agreement when compared to our Monte Carlo and molecular dynamics simulations for spherical geometry and with respect to previous anisotropic reference HNC calculations in the planar limit. We report an analysis of the potential vs charge relationship, radial distribution functions, mean electrostatic potential and cumulative reduced charge for representative cases of 1:1 and 2:2 salts with a size asymmetry ratio of 2. Our results are collated with those of the Modified Gouy-Chapman (MGC) and unequal radius Modified Gouy-Chapman (URMGC) theories and with those of HNC/MSA in the restricted primitive model (RPM) to assess the importance of size asymmetry effects. One of the most striking characteristics found is that,\textit{contrary to the general belief}, away from the point of zero charge the properties of an asymmetric electrical double layer (EDL) are not those corresponding to a symmetric electrolyte with the size and charge of the counterion, i.e. \textit{counterions do not always dominate}. This behavior suggests the existence of a new phenomenology in the EDL that genuinely belongs to a more realistic size-asymmetric model where steric correlations are taken into account consistently. Such novel features can not be described by traditional mean field theories like MGC, URMGC or even by enhanced formalisms, like HNC/MSA, if they are based on the RPM.Comment: 29 pages, 13 figure

Vortices on demand in multicomponent Bose-Einstein condensates

We present a simple mechanism to produce vortices at any desired spatial locations in harmonically trapped Bose-Einstein condensates (BEC) with multicomponent spin states coupled to external transverse and axial magnetic fields. The vortices appear at the spatial points where the spin-transverse field interaction vanishes and, depending on the multipolar magnetic field order, the vortices can acquire different predictable topological charges. We explicitly demonstrate our findings, both numerically and analytically, by analyzing a 2D BEC via the Gross-Pitaevskii equation for atomic systems with either two or three internal states. We further show that, by an spontaneous symmetry breaking mechanism, vortices can appear in any spin component, unless symmetry is externally broken at the outset by an axial field. We suggest that this scenario may be tested using an ultracold gas of $^{87}$Rb occupying all three $F = 1$ states in an optical trap.Comment: 11 pages, 9 figures, (Accepted in PRA

Fossil group origins - VI. Global X-ray scaling relations of fossil galaxy clusters

We present the first pointed X-ray observations of 10 candidate fossil galaxy groups and clusters. With these Suzaku observations, we determine global temperatures and bolometric X-ray luminosities of the intracluster medium (ICM) out to $r_{500}$ for six systems in our sample. The remaining four systems show signs of significant contamination from non-ICM sources. For the six objects with successfully determined $r_{500}$ properties, we measure global temperatures in the range $2.8 \leq T_{\mathrm{X}} \leq 5.3 \ \mathrm{keV}$, bolometric X-ray luminosities of $0.8 \times 10^{44} \ \leq L_{\mathrm{X,bol}} \leq 7.7\times 10^{44} \ \mathrm{erg} \ \mathrm{s}^{-1}$, and estimate masses, as derived from $T_{\mathrm{X}}$, of $M_{500} > 10^{14} \ \mathrm{M}_{\odot}$. Fossil cluster scaling relations are constructed for a sample that combines our Suzaku observed fossils with fossils in the literature. Using measurements of global X-ray luminosity, temperature, optical luminosity, and velocity dispersion, scaling relations for the fossil sample are then compared with a control sample of non-fossil systems. We find the fits of our fossil cluster scaling relations are consistent with the relations for normal groups and clusters, indicating fossil clusters have global ICM X-ray properties similar to those of comparable mass non-fossil systems.Comment: 17 pages, 7 figures, 8 tables. Accepted for publication in MNRA

Climate change and the kidney

The worldwide increase in temperature has resulted in a marked increase in heat waves (heat extremes) that carries a markedly increased risk for morbidity and mortality. The kidney has a unique role not only in protecting the host from heat and dehydration but also is an important site of heat-associated disease. Here we review the potential impact of global warming and heat extremes on kidney diseases. High temperatures can result in increased core temperatures, dehydration, and blood hyperosmolality. Heatstroke (both clinical and subclinical whole-body hyperthermia) may have a major role in causing both acute kidney disease, leading to increased risk of acute kidney injury from rhabdomyolysis, or heat-induced inflammatory injury to the kidney. Recurrent heat and dehydration can result in chronic kidney disease (CKD) in animals and theoretically plays a role in epidemics of CKD developing in hot regions of the world where workers are exposed to extreme heat. Heat stress and dehydration also has a role in kidney stone formation, and poor hydration habits may increase the risk for recurrent urinary tract infections. The resultant social and economic consequences include disability and loss of productivity and employment. Given the rise in world temperatures, there is a major need to better understand how heat stress can induce kidney disease, how best to provide adequate hydration, and ways to reduce the negative effects of chronic heat exposure.Published versio

Charge Fluctuation Forces Between Stiff Polyelectrolytes in Salt Solution: Pairwise Summability Re-examined

We formulate low-frequency charge-fluctuation forces between charged cylinders - parallel or skewed - in salt solution: forces from dipolar van der Waals fluctuations and those from the correlated monopolar fluctuations of mobile ions. At high salt concentrations forces are exponentially screened. In low-salt solutions dipolar energies go as $R^{-5}$ or $R^{-4}$; monopolar energies vary as $R^{-1}$ or $\ln{R}$, where $R$ is the minimal separation between cylinders. However, pairwise summability of rod-rod forces is easily violated in low-salt conditions. Perhaps the most important result is not the derivation of pair potentials but rather the demonstration that some of these expressions may not be used for the very problems that originally motivated their derivation.Comment: 8 pages and 1 fig in ps forma