3,537 research outputs found

    “Zombie attack” a new way to teach Chemistry

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    The Higher Education requires new models which allow training people able to adapt and survive in changing environments. It is based on the use of technologies and the adaptation of knowledge to people. It is about an education according to circumstances, which is adapted to context and virtual behaviour of people. One of the main difficulties that lecturers find in the classroom is how to maintain students' attention and interest in their subject, especially when students also think that the subject is not important for their training. In order to motivate these students, innovation in educational techniques and methodologies, such as experiential learning, are progressively being imposed to and/or coordinated with the traditional ones. Escape Room is a very modern concept in education, based on the development of mental skills for the solution of enigmas and problems. It is a tool to develop the cooperative, cognitive, deductive and logical reasoning skills of the students. In this work, an educational gamification experience based on the escape room concept is presented. The students have 1 hour and 30 minutes to carry out this activity. They will have to solve four puzzles and enigmas that will give them the key to open a treasure chest and finally let them escape from the classroom. Logic, ingenuity and teamwork will allow participants to develop not only chemical competence, but also other basic skills. The story that is told throughout the escape room is a zombie attack: the city has been infected (with a virus) and only the occupants of the room where the activity takes place have not been infected. In addition, they can all protect themselves if they are able to open the chest where the antidote is located. The aim of this activity is to enhance the knowledge acquired throughout the semester as well as the development of skills.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

    Dynamics of Annihilation II: Fluctuations of Global Quantities

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    We develop a theory for fluctuations and correlations in a gas evolving under ballistic annihilation dynamics. Starting from the hierarchy of equations governing the evolution of microscopic densities in phase space, we subsequently restrict to a regime of spatial homogeneity, and obtain explicit predictions for the fluctuations and time correlation of the total number of particles, total linear momentum and total kinetic energy. Cross-correlations between these quantities are worked out as well. These predictions are successfully tested against Molecular Dynamics and Monte-Carlo simulations. This provides strong support for the theoretical approach developed, including the hydrodynamic treatment of the spectrum of the linearized Boltzmann operator. This article is a companion paper to arXiv:0801.2299 and makes use of the spectral analysis reported there.Comment: 19 page

    Changes induced by glucose in the plasma membrane properties of pancreatic islets

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    Partially purified membranes obtained from rat pancreatic isolated islets preincubated for 3 min with 3.3 and 16.6 mM glucose were labelled with 1,6-diphenyl-1,3,5-hexatriene to study fluorescence polarization. Other islets, incubated for 5 min with the same glucose concentration, were extracted and phospholipids separated by thin-layer chromatography. The composition of phospholipids of fatty acids was then studied by gas-liquid chromatography. Arrhenius plots of the microviscosity in membranes obtained from islets exhibited two components, a steeper slope below 18 degrees C and a gentler slope above 18 degrees C, indicating greater flow activation energy at temperatures below the transition point. Exposure of islets to 16.6 mM glucose significantly increased the flow activation energy (delta E), below and above the transition point. Islets incubated for 5 min with 16.6 mM glucose showed an increase in the percentage composition of 12:0 and 18:2 together with a decrease in the 20:2 W6 and 22:3 W3 fatty acids esterified to phospholipids. Regardless of these changes, no significant alterations occurred in the proportion of saturated fatty acids or in the double bond index; these measurements therefore did not account for the effects of glucose concentration in flow activation energy. The thermotropic changes reported here might be the consequence of some degree of disorder induced by glucose upon the membrane structure. This order alteration could either favor the membrane fusion which occurs during the emiocytosis or only reflects the consequence of such a process.Facultad de Ciencias MĂ©dica

    Distributed feedback lasers based on dichromated poly(vinyl alcohol) reusable surface-relief gratings

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    A simple, low-cost and versatile holographic method to produce reusable surface-relief gratings on dichromated poly(vinyl alcohol) (DCPVA) films, with periods Λ ≥ 270 nm and modulation depths up to 300 nm, is reported. DCPVA presents processing advantages with respect to other photoresists, such as dichromated gelatine, i.e. higher light sensitivity, simpler fabrication process and better batch to batch reproducibility. The successful use of these DCPVA relief gratings as distributed feedback (DFB) laser resonators is demonstrated. Second-order DFB devices emitting in the wavelength range 577-614 nm have been easily prepared by coating a dye-doped polymer film on top of the resonators.We thank the Spanish Government (MINECO) and the European Union (FEDER) for grant no. MAT2011-28167-C02

    The effect of transport time, season and position on the truck on stress response in rabbits

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    [EN] The present study analyzed the effect of transport time, season and position on the truck on physiological stress response of commercial rabbits in Aragón (Spain). A total of 156 animals were sampled in a 2x2x3 factorial design testing two transport times: short, 1 hour (1hT) and long, 7 hours (7hT), in two different seasons: hot, during summer (HT) and cold during winter (CT), and three different positions on the truck: upper, middle or lower decks in multi-floor cages on rolling stands (MFRS-top, MFRS-middle and MFRS-bottom). Three replicates were performed per treatment. Blood samples were taken at sticking during slaughter to compare hematocrite, corticosterone, glucose, lactate and Creatine Kinase (CK) levels as well as the ultimate pH of the carcass (pH24). Corticosterone and CK levels were highest in 1hT rabbits. With respect to season, colder temperatures increased corticosterone, while warmer temperatures increased CK (P<0.001). Regarding position on the truck, MFRS-middle and bottom rabbits had higher levels of glucose, corticosterone and CK. The pH24 values were within normal ranges for all treatments but slightly higher for animals transported in winter. In general, transport time and season were significant stressors for commercial rabbits, due to the effects on their physiological states. Position on the truck seems to have an effect on stress response to transport in rabbits. However, pH24, which is considered one of the main parameters of welfare measurements, was not affected by transport time or position on the truck.Our project was financed by the Spanish Ministry of Science and Technology (CICYT AGL-2002-01346). The authors wish to thank CUIN S.L. in Villanueva de Gállego and the associations MADECUN and ASESCU for their collaboration.Liste, M.; María, GA.; García-Belenguer, S.; Chacón, G.; Gazzola, P.; Villarroel, M. (2008). The effect of transport time, season and position on the truck on stress response in rabbits. World Rabbit Science. 16(4). doi:10.4995/wrs.2008.618SWORD16

    Perylenediimide-based distributed feedback lasers with holographic relief gratings on dichromated gelatine

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    One dimensional second-order distributed feedback (DFB) lasers consisting of polystyrene (PS) films doped with a perylenediimide laser dye, deposited over dichromated gelatine (DCG) photoresist layers with solvent resistant relief gratings recorded by holographic lithography, are reported. The advantage of using the grating on DCG in the final device is that the fabrication process is simplified and the grating pattern better preserved, since no etching methods to transfer the grating to another substrate are needed. A very simple model, proposed to explain the experimental waveguide properties, has allowed identifying the waveguide mode at which DFB emission appears, which was the key to optimize the device performance. In the frame of this model, the thickness of the PS and DCG films could be adjusted in order to minimize the laser threshold and to control its wavelength tuneability. The performance of these lasers is comparable to that of recently reported devices based on the same active material, but deposited over high-quality DFB gratings engraved on SiO2 by nanoimprint lithography.We thank support from the Spanish Government (MINECO) and the European Community (FEDER) through Grant Nos. MAT2008-06648-C02 and MAT-2011-28167-C02, as well as to the University of Alicante. M.G.R. was supported by a CSIC fellowship within the program JAE
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