Continuity of Lyapunov Exponents for Random 2D Matrices

The Lyapunov exponents of locally constant GL(2;C)-cocycles over Bernoulli shifts depend continuously on the cocycle and on the invariant probability. The Oseledets decomposition also depends continuously on the cocycle, in measure

Accuracy Issues for Numerical Waveforms

We study the convergence properties of our implementation of the 'moving punctures' approach at very high resolutions for an equal-mass, non-spinning, black-hole binary. We find convergence of the Hamiltonian constraint on the horizons and the L2 norm of the Hamiltonian constraint in the bulk for sixth and eighth-order finite difference implementations. The momentum constraint is more sensitive, and its L2 norm shows clear convergence for a system with consistent sixth-order finite differencing, while the momentum and BSSN constraints on the horizons show convergence for both sixth and eighth-order systems. We analyze the gravitational waveform error from the late-inspiral, merger, and ringdown. We find that using several lower-order techniques for increasing the speed of numerical relativity simulations actually lead to apparently non-convergent errors. Even when using standard high-accuracy techniques, rather than seeing clean convergence, where the waveform phase is a monotonic function of grid resolution, we find that the phase tends to oscillate with resolution, possibly due to stochastic errors induced by grid refinement boundaries. Our results seem to indicate that one can obtain gravitational waveform phases to within 0.05 rad. (and possibly as small as 0.015 rad.), while the amplitude error can be reduced to 0.1%. We then compare with the waveforms obtained using the cZ4 formalism. We find that the cZ4 waveforms have larger truncation errors for a given resolution, but the Richardson extrapolation phase of the cZ4 and BSSN waveforms agree to within 0.01 rad., even during the ringdown.Comment: version accepted to PR

Resistance to cisplatin and paclitaxel does not affect the sensitivity of human ovarian cancer cells to antiprogestin- induced cytotoxicity

BACKGROUND: Antiprogestin compounds have been shown to be effective in blocking the growth of ovarian cancer cells of different genetic backgrounds. Herein we studied the anti-ovarian cancer effect of a series of antiprogestins sharing the chemical backbone of the most characterized antiprogestin, mifepristone, but with unique modifications in position C-17 of the steroid ring. We assessed the effect of mifepristone-like antiprogestins on the growth of ovarian cancer cells sensitive to the standard combination therapy cisplatin-paclitaxel or made double-resistant upon six cycles of pulse-selection with the drugs used at clinically relevant concentrations and exposure times. METHODS: IGROV-1 and SKOV-3 cells were pulsed with 20 μM cisplatin for 1 h followed by 100 nM paclitaxel for 3 h once a week for six weeks. The cells that did not die and repopulate the culture after the chemotherapies were termed Platinum-Taxane-EScape cells (PTES). Parental cells were compared against their PTES derivatives in their responses to further platinum-taxane treatments. Moreover, both ovarian cancer cells and their PTES siblings were exposed to escalating doses of the various antiprogestin derivatives. We assessed cell growth, viability and sub-G1 DNA content using microcapillary cytometry. Cyclin-dependent kinase inhibitors p21(cip1) and p27(kip1) and cleavage of downstream caspase-3 substrate PARP were used to assess whether cell fate, as a consequence of treatment, was limited to cytostasis or progressed to lethality. RESULTS: Cells subjected to six pulse-selection cycles of cisplatin-paclitaxel gave rise to sibling derivatives that displayed ~2-7 fold reduction in their sensitivities to further chemotherapy. However, regardless of the sensitivity the cells developed to the combination cisplatin-paclitaxel, they displayed similar sensitivity to the antiprogestins, which blocked their growth in a dose-related manner, with lower concentrations causing cytostasis, and higher concentrations causing lethality. CONCLUSIONS: Antiprogestins carrying a backbone similar to mifepristone are cytotoxic to ovarian cancer cells in a manner that does not depend on the sensitivity the cells have to the standard ovarian cancer chemotherapeutics, cisplatin and paclitaxel. Thus, antiprogestin therapy could be used to treat ovarian cancer cells showing resistance to both platinum and taxanes.Fil: Gamarra Luques, Carlos Diego. University of South Dakota. Sanford School of Medicine. Division of Basic Biomedical Sciences; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Hapon, María Belén. University of South Dakota. Sanford School of Medicine. Division of Basic Biomedical Sciences; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Goyeneche, Alicia. University of South Dakota. Sanford School of Medicine. Division of Basic Biomedical Sciences; Estados UnidosFil: Telleria, Carlos Marcelo. University of South Dakota. Sanford School of Medicine. Division of Basic Biomedical Sciences; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; Argentin

Quantum phase diagram of a frustrated antiferromagnet on the bilayer honeycomb lattice

We study the spin-1/2 Heisenberg antiferromagnet on a bilayer honeycomb lattice including interlayer frustration. Using a set of complementary approaches, namely Schwinger bosons, dimer series expansion, bond operators, and exact diagonalization, we map out the quantum phase diagram. Analyzing ground state energies and elementary excitation spectra, we find four distinct phases, corresponding to three collinear magnetic long range ordered states, and one quantum disordered interlayer dimer phase. We detail, that the latter phase is adiabatically connected to an "exact" singlet product ground state of the the bilayer which exists along a line of maximum interlayer frustration. The order within the remaining three phases will be clarified.Comment: 12 pages, 12 figure

The early stages of teaching: Teachers with good principles

The teachers in their learning process, go through different stages. Of all these phases which we are most interested in this article is the one that begins with the first contacts with the reality of the school, assuming the role reserved for vocational teachers. Teacher induction is the time period covering the early years, in which teachers have to make the transition from students to teachers. It is a period of tension and intensive learning contexts and generally unknown during which the novice teachers should acquire professional knowledge in addition to ensuring a certain balance. Induction programs for novice teachers are a real alternative to further that the first years as teachers are not frustrating year

"Alacena", An open Learning Design Repository for University Teaching

Ser docente significa estar implicado en el diseño de actividades de aprendizaje. La profesión docente se ha transformado en una «profesión del conocimiento» no ya porque el conocimiento haya sido o sea el componente legitimador de la profesión, sino porque el docente es el diseñador de ambientes de aprendizaje y tiene la capacidad de rentabilizar los espacios donde se produce el conocimiento. Ahora bien, estos ambientes de aprendizaje durante mucho tiempo han quedado regulados en el ámbito de privacidad del aula y a la complicidad con el alumnado. Uno de los aspectos positivos que ha tenido la puesta en marcha del Espacio Europeo de Educación Superior ha sido aportar una mayor transparencia a los procesos de diseño del aprendizaje de los alumnos. Nuestro objetivo en este estudio consistió en identificar, representar y documentar una amplia variedad de diseños de aprendizaje realizados por docentes con amplia experiencia innovadora y que pudieran estar disponibles y accesibles a través de Internet. El profesorado que ha participado en este estudio lo han conformado un total de cincuenta y ocho docentes principalmente de las diferentes universidades andaluzas y de las cinco ramas de conocimiento. A partir de entrevistas procedimos a representar el total de secuencias de aprendizaje que están disponibles en el repositorio de secuencias que hemos denominado «Alacena». Este repositorio está accesible en la página web de nuestro grupo de investigación http://prometeo.us.es/idea. Como conclusiones del estudio se constata que existen diseños del aprendizaje innovadores y universitarios que pretenden promover en el alumnado una alta comprensión de lo aprendido a través de su implicación en procesos de indagación y/o colaboración y que son representación de buenas prácticas de enseñanzaBeing a teacher means being involved in the design of learning activities. The teaching profession has become a «profession of knowledge», not because knowledge was or is the legitimate component of the profession, but because the teacher is the designer of learning environments and has the ability to design the spaces where knowledge is being produced. But these learning environments have long been regulated to the privacy of the classroom environment with student complicity. One positive aspect of the launch of the European Higher Education Area has been to bring greater transparency to the process of designing teaching and student learning. Our objective in this study was to identify, represent and document a wide variety of learning designs made by experienced and innovative teachers. We hope this repository will be available and accessible to every teacher through the Internet. The participants in this study were 58 teachers mainly from universities in Andalusia and the five branches of knowledge. From interviews we proceeded to represent all the learning sequences, available in the repository of sequences that we named «Ala cena». This repository is accessible on our research group’s website (http://prometeo.us.es/idea). The conclusions of our study were that there are innovative learning designs aimed at promoting a greater understanding of what students learn through their involvement in processes of inquiry and/or collaboration, and they are representative of good teaching practices in universitie