Un sitio web para la aproximación fenomenológica de la enseñanza de la luz y la visión

Presentamos las características de una página web sobre «Luz y visión» que diseñamos y preparamos para profesores (desde parvulario a 4º de ESO) con la intención de guiarlos por un itinerario desde el conocimiento que da el sentido común hasta la física. Además de experimentos y modelos interpretativos de fenomenología básica, proponemos ejemplos de trabajos realizados en escuelas por profesores (en parvularios y escuelas primarias y secundarias) en colaboración con nuestro grupo de investigación. La página fue desarrollada en el marco del proyecto italiano SeCiF (Spiegare e Capire in Fisica - Explicar y comprender en física) dedicado a preparar materiales (principalmente materiales de página web y redes telemáticas) para la formación de profesores en servicio y futuros profesores sobre una enseñanza innovadora de la física desde el parvulario a la escuela secundaria.We will present the characteristics of a Web site about «Light and Vision» we designed and prepared for teachers (of grades K-10) with the aim to drive them along a path from commonse knowledge to physics. In addition to experiments and interpretive models of basic phenomenology we propose examples of works made in schools by teachers (in some kindergarten, primary and secondary school classes) working with our research group. The site was developed inside of the Italian project SeCiF (Spiegare e Capire in Fisica - Explaining and Understanding in Physics) devoted to prepare materials (mainly Web materials and telematic networks) for in service and future teachers training about an innovative teaching of physics from kindergarten to secondary school

The future of the Mediterranean agri-food systems: trends and perspectives from a Delphi survey

The Mediterranean region is widely acknowledged as one of the most exposed in the world to the effects of climate change, water scarcity, biodiversity loss and land degradation, coupled with a nutrition transition of its populations. In such a context, to explore the evolution of the region is of both political and theoretical interest. This study presents the result of a scenario-building exercise, based on a Delphi method – an interactive forecasting technique – relying upon about 60 practitioners, experts and academics representing 19 Mediterranean countries and a wide range of disciplines and expertise. The present article has three main purposes. First, to identify the main challenges, trends and driving forces that influence the agri-food systems in the Mediterranean over a short (2020) and medium (2030) term. Second, to discuss the alternative policy responses to the challenges that the region will face in terms of water resource management, farming systems and agri-food value chains in terms of desirability and feasibility. Thirdly, to provide informed, evidence-based recommendations that might help different stakeholders to take action in the region’s agri-food sector. Based on this Delphi’s results, the study suggests that the gap between the countries in the South and the North of the Mediterranean in terms of challenges posed in water management, farming systems and the agri-food value chain is expected to grow. Experts agree that climate change is going to play a key role in the future of both sides of the Mediterranean, but with a differential impact in the sub-two regions. Nutrition-related challenges will exert a growing pressure especially in the Southern Mediterranean countries. A set of desirable and feasible policy option for addressing the Mediterranean food-related challenges are discussed

Enantiomeric separations by capillary electrophoresis: Theoretical method to determine optimum chiral selector concentration

A method to optimize the ligand concentration [S] in the background electrolyte of capillary electrophoresis separations is presented. It is based on the use of a model which predicts apparent electrophoretic mobilities as a function of ligand concentration (expressed as p[S] = −log[S]). This model is employed to compose the expression of a recently proposed criterion to qualify separations in electrophoresis. Two strategies to find the optimum p[S], leading to the best separation of all compounds, are explained: 1.- a graphical method using a windows map depicting the single separation criteria between all possible combination of compounds by pairs, and 2.- an analytical method where an extended multicriterion optimization function is composed and optimum p[S] is found by mathematical maximization. The procedure is applied to a hard-to-separate model system: enantiomeric separations of racemic mixtures. 2-Hydroxypropyl-β-cyclodextrin was chosen as a model ligand, and four pharmaceutical drugs as model analytes. In order to demonstrate the performance of the procedure, results of electrophoretic separations obtained at p[S] found as optimum are compared with separations obtained at p[S] values slightly higher and lower than the optimum.Fil: Lancioni, Carlina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Keunchkarian, Sonia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Castells, Cecilia Beatriz Marta. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gagliardi, Leonardo Gabriel. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Determination of thermodynamic binding constants by affinity capillary electrophoresis

A strategy to study thermodynamic binding constants by affinity capillary electrophoresis (ACE) is presented. In order to simplify mathematical treatment, analogy with acid-base dissociation equilibrium is proposed: instead of ligand concentration [X], negative logarithm of ligand concentration (or activity), pX = -log[X], is used. On this base, and taking into account ionic activities, a general procedure for obtaining thermodynamic binding constants is proposed. In addition, the method provides electrophoretic mobilities of the free analyte and analyte-ligand complex, even when binding constants are low and thus, the complexed analyte fraction is also low. This is useful as a base to rationally analyze a diversity of situations, i.e., different mathematical dependencies are obtained when analytes and ligands with different charges are combined. Practical considerations are given for carrying out a full experimental design. Enantiomeric ACE separation based on the use of chiral selectors is addressed. 2-hydroxypropyl-β-cyclodextrin was chosen as a model ligand, and both enantiomeric forms of four pharmaceutical drugs (propranolol, pindolol, oxprenolol and homatropine methylbromide) were considered as model analytes. Practical aspects are detailed and thermodynamic binding constants as well as free and complexed analytes mobilities are determined.Fil: Lancioni, Carlina. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Grupo Cromatografía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Keunchkarian, Sonia. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Grupo Cromatografía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Castells, Cecilia Beatriz Marta. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Gagliardi, Leonardo Gabriel. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Long-term low-dose tolvaptan efficacy and safety in SIADH

Purpose: Tolvaptan, a selective vasopressin V2-receptor antagonist, is approved for the treatment of SIADH-related hyponatremia, but its use is limited. The starting dose is usually 15 mg/day, but recent clinical experience suggests a lower starting dose (<15 mg/day) to reduce the risk of sodium overcorrection. However, long-term low-dose efficacy and safety has not been explored, so far. Aim of our study is to characterize safety and efficacy of long-term SIADH treatment with low-dose Tolvaptan. Methods: We retrospectively evaluated 11 patients receiving low-dose Tolvaptan (<15 mg/day) for chronic SIADH due to neurological, idiopathic and neoplastic causes. Plasma sodium levels were measured before and 1, 3, 5, 15 and 30 days after starting Tolvaptan and then at 3-month intervals. Anamnestic and clinical data were collected. Results: Mean time spanned 27.3 ± 29.8 months (range 6 months-7 years). Mean plasma sodium levels were within normal range 1, 3 and 6 months after starting Tolvaptan as well as after 1, 2, 3, 5 and 7 years of therapy. Neither osmotic demyelination syndrome nor overcorrection were observed. Plasma sodium levels normalization was associated with beneficial clinical effects. Neurological patients obtained seizures disappearance, improvement in neurological picture and good recovery from rehabilitation. Neoplastic patients were able to start chemotherapy and improved their general condition. Patients did not show hypernatremia during long-term follow-up and reported mild thirst and pollakiuria. Conclusions: The present study shows that long-term low-dose Tolvaptan is safe and effective in SIADH treatment. No cases of overcorrection were documented and mild side effects were reported

Modeling retention and selectivity as a function of pH and column temperature in liquid chromatography

In reversed-phase liquid chromatography (RPLC), the retention of weak acids and bases is a sigmoidal function of the mobile-phase pH. Therefore, pH is a key chromatographic variable to optimize retention and selectivity. Furthermore, at an eluent pH close to the pKa of the solute, the dependence of ionization of the buffer and solute on temperature can be used to improve chromatographic separations involving ionizable solutes by an adequate handling of column temperature. In this paper, we derive a general equation for the prediction of the retentive behavior of ionizable compounds upon simultaneous changes in mobile-phase pH and column temperature. Four experiments, two limiting pH values and two temperatures, provide the input data that allow predictions in the whole range of these two variables, based on the thermodynamic fundamentals of the involved equilibria. Also, the study demonstrates the significant role that the choice of the buffer compound would have on selectivity factors in RPLC at temperatures higher than 25 °C. © 2006 American Chemical Society.Fil: Gagliardi, Leonardo Gabriel. Universidad de Barcelona; España. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Castells, Cecilia Beatriz Marta. Universidad Nacional de La Plata; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Ràfols, Clara. Universidad de Barcelona; EspañaFil: Rosés, Martí. Universidad de Barcelona; EspañaFil: Bosch, Elisabeth. Universidad de Barcelona; Españ

The spreading of the invasive sacred ibis in Italy

The spreading of invasive species in new continents can vary from slow and limited diffusion to fast colonisations over vast new areas. We studied the sacred ibis Threskiornis aethiopicus along a 31-year period, from 1989 to 2019, with particular attention to the first area of release in NW Italy. We collected data on species distribution through observations by citizen science projects, population density by transects with distance method, breeding censuses at colonies, and post breeding censuses at roosts. The birds counted at winter roosts in NW Italy increased from a few tens up to 10,880 individuals in 2019. Sacred ibises started breeding in 1989, with a single nest in north-western Italy. The number of breeders remained very low until 2006, when both overwintering and breeding sacred ibises started to increase exponentially and expand their range throughout northern Italy with isolated breeding cases in central Italy. In 2019, the number of nests had increased to 1249 nests in 31 colonies. In NW Italy, the density of foraging birds averaged 3.9 ind./km2 in winter and 1.5 ind./km2 in the breeding period, with a mean size of the foraging groups of 8.9 and 2.1 birds respectively. Direct field observations and species distribution models (SDM) showed that foraging habitats were mainly rice fields and wetlands. A SDM applied to the whole Italian peninsula plus Sardinia and Sicily showed that the variables best related to the SDM were land class (rice fields and wetlands), altitude, and the temperature seasonality. The areas favourable for species expansion encompass all the plains of Northern Italy, and several areas of Tuscany, Latium, Sardinia, and Apulia

Peritoneal and hematogenous metastases of ovarian cancer cells are both controlled by the p90RSK through a self-reinforcing cell autonomous mechanism

The molecular mechanisms orchestrating peritoneal and hematogenous metastases of ovarian cancer cells are assumed to be distinct. We studied the p90RSK family of serine/threonine kinases that lie downstream the RAS-ERK/MAPK pathway and modulate a variety of cellular processes including cell proliferation, survival, motility and invasiveness. We found the RSK1 and RSK2 isoforms expressed in a number of human ovarian cancer cell lines, where they played redundant roles in sustaining in vitro motility and invasiveness. In vivo, silencing of both RSK1 and RSK2 almost abrogated short-term and long-term metastatic engraftment of ovarian cancer cells in the peritoneum. In addition, RSK1/RSK2 silenced cells failed to colonize the lungs after intravenous injection and to form hematogenous metastasis from subcutaneous xenografts. RSK1/RSK2 suppression resulted in lessened ovarian cancer cell spreading on endogenous fibronectin (FN). Mechanistically, RSK1/RSK2 knockdown diminished FN transcription, α5β1 integrin activation and TGF-β1 translation. Reduced endogenous FN deposition and TGF-β1 secretion depended on the lack of activating phosphorylation of the transcription/translation factor YB-1 by p90RSK. Altogether data show how p90RSK activates a self-reinforcing cell autonomous pro-adhesive circuit necessary for metastatic seeding of ovarian cancer cells. Thus, p90RSK inhibitors might hinder both the hematogenous and the peritoneal metastatic spread of human ovarian cancer