Parametrically excited surface waves in magnetic fluids: observation of domain structures

Observations of parametrically excited surface waves in a magnetic fluid are presented. Under the influence of a magnetic field these waves have a non--monotonic dispersion relation, which leads to a richer behavior than in ordinary liquids. We report observation of three novel effects, namely: i) domain structures, ii) oscillating defects and iii) relaxational phase oscillations.Comment: to be published in Physical Review Letter

Assessment of Natural Resources Use for Sustainable Development - DPSIR Framework for Case Studies in Portsmouth and Thames Gateway, U.K.

This chapter reports on the uses of the DPSIR framework to assess the sustainability of the intertidal environments within the two UK case study areas, Portsmouth and Thames Gateway. It focuses on statutory conservation areas dominated by intertidal habitats. Two are located in Portsmouth (Portsmouth and Langstone Harbours) and four in the Thames Gateway (Benfleet Marshes, South Thames Estuary, Medway Estuary and the Swale in the Thames Gateway). Based on the reduction of a number of pressures and impacts observed in recent decades and the improvement of overall environmental quality, all six SSSIs are considered to be sustainable in the short and medium term. In the future, it is possible that the impacts of climate change, especially sea-level rise, might result in further reduction in the area and/or quality of intertidal habitats. Further integration between conservation and planning objectives (both for urban development and management of flood risk) at local level is needed to support the long-term sustainability of intertidal habitats

Qualitative results for a mixture of Green-Lindsay thermoelastic solids

We study qualitative properties of the solutions of the system of partial differential equations modeling thermomechanical deformations for mixtures of thermoelastic solids when the theory of Green and Lindsay for the heat conduction is considered. Three dissipation mechanisms are proposed in the system: thermal dissipation, viscosity e ects on one constituent of the mixture and damping in the relative velocity of the two displacements of both constituents. First, we prove the existence and uniqueness of the solutions. Later we prove the exponential stability of the solutions over the time. We use the semigroup arguments to establish our resultsPeer ReviewedPostprint (author's final draft

Design of polymer-based antimicrobial hydrogels through physico-chemical transition

The antimicrobial activity represents a cornerstone in the development of biomaterials: it is a leading request in many areas, including biology, medicine, environment and industry. Over the years, different polymeric scaffolds are proposed as solutions, based on the encapsulation of metal ions/particles, antibacterial agents or antibiotics. However, the compliance with the biocompatibility criteria and the concentration of the active principles to avoid under- and over-dosing are being debated. In this work, we propose the synthesis of a versatile hydrogel using branched polyacrylic acid (carbomer 974P) and aliphatic polyetherdiamine (elastamine\uae) through physico-chemical transition, able to show its ability to counteract the bacterial growth and infections thanks to the polymers used, that are not subjected to further chemical modifications. In particular, the antimicrobial activity is clearly demonstrated against Staphyloccoccus aureus and Candida albicans, two well-known opportunistic pathogens. Moreover, we discuss the hydrogel use as drug carrier to design a unique device able to combine the antibacterial/antimicrobial properties to the controlled drug delivery, as a promising tool for a wide range of biomedical applications

Simultaneous 3D measurement of the translation and rotation of finite size particles and the flow field in a fully developed turbulent water flow

We report a novel experimental technique that measures simultaneously in three dimensions the trajectories, the translation, and the rotation of finite size inertial particles together with the turbulent flow. The flow field is analyzed by tracking the temporal evolution of small fluorescent tracer particles. The inertial particles consist of a super-absorbent polymer that renders them index and density matched with water and thus invisible. The particles are marked by inserting at various locations tracer particles into the polymer. Translation and rotation, as well as the flow field around the particle are recovered dynamically from the analysis of the marker and tracer particle trajectories. We apply this technique to study the dynamics of inertial particles much larger in size (Rp/{\eta} \approx 100) than the Kolmogorov length scale {\eta} in a von K\'arm\'an swirling water flow (R{\lambda} \approx 400). We show, using the mixed (particle/fluid) Eulerian second order velocity structure function, that the interaction zone between the particle and the flow develops in a spherical shell of width 2Rp around the particle of radius Rp. This we interpret as an indication of a wake induced by the particle. This measurement technique has many additional advantages that will make it useful to address other problems such as particle collisions, dynamics of non-spherical solid objects, or even of wet granular matter.Comment: 18 pages, 7 figures, submitted to "Measurement Science and Technology" special issue on "Advances in 3D velocimetry

Oxidative stress and DNA damage in agricultural workers after exposure to pesticides

Background: Recent epidemiological studies on workers describe that exposure to pesticides can induce oxidative stress by increased production of free radicals that can accumulate in the cell and damage biological macromolecules, for example, RNA, DNA, DNA repair proteins and other proteins and/or modify antioxidant defense mechanisms, as well as detoxification and scavenger enzymes. This study aimed to assess oxidative stress and DNA damage among workers exposed to pesticides. Methods: For this purpose, 52 pesticide exposed workers and 52 organic farmers were enrolled. They were assessed: the pesticide exposure, thiobarbituric acid reactive substances (TBARS), total glutathione (TG), oxidized glutathione levels (GSSG), and 8-oxo-7,8-dihydro-2\u2032-deoxyguanosine (8-oxodG), levels. Results: Correlation between pesticide exposure was positively associated with high TBARS and 8-oxodG levels (p < 0.001). A negative association was founded with TG and GSSG and pesticide exposure. Conclusions: The present investigation results seem to indicate a mild augment in oxidative stress associated with pesticide exposure, followed by an adaptive response to increase the antioxidant defenses to prevent sustained oxidative adverse effects stress

194preal life utilization of genomic testing for invasive breast cancer patients in italy and france reduces chemotherapy recommendations

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Educación STEM como base de competencias científicas de docentes universitarios

Durante la presente década se ha intensificado la educación experimental de ciencias, en forma integrada con tecnologías digitales, desarrollos ingenieriles y algoritmos matemáticos, que constituyen la Educación STEM (Science, Technology, Engineering ,Mathematics). Este concepto de educación ha tenido, como consecuencia, una repercusión trascendente en la comunidad de docentes de ciencias y en la pedagogía practicada. Este cambio cultural requiere que los docentes profundicen su desarrollo profesional, a los efectos de incorporar en un el Aula – Laboratorio nuevos recursos didácticos. Todo ello implica introducir un cambio en la metodología de trabajo, en la adquisición de nuevos conocimientos y en las prácticas experimentales. Con el objeto de llevar a cabo este cambio, se ha planificado, como estrategia básica, el desarrollo de Unidades Didácticas cuya estructura difiere de la exposición experta del docente y de la exposición de los textos de libros corrientes y en Internet. Las Unidades Didácticas desarrolladas cubren los temas curriculares de ciencias físicas, químicas y biológicas de carreras universitarias de ciencias e ingeniería. La estructura cuenta con una organización pedagógica de experiencias centrada en el alumno para que trabaje con sus manos y su mente (pensamiento visible)