From Student Shyness to Student Voice: Mapping Biliteracy Teaching in Indigenous Contexts

Drawing on an ethnographic monitoring engagement with Kichwa intercultural bilingual educators in the Peruvian Amazon, we argue for ethnographic monitoring (Hymes, 1980) as a method and the continua of biliteracy (Hornberger, 1989, 1990, 2003; Hornberger & Skilton-Sylvester, 2000) as a heuristic for mapping biliteracy teaching in Indigenous contexts of bilingualism. Through our mapping, we uncover tensions in the teaching of majoritized languages in Indigenous contexts of postcoloniality, challenge constructs of student shyness, and propose pedagogies to support the flourishing of student voice in bilingual education

Emerging Spin-Orbit Torques in Low Dimensional Dirac Materials

We report a theoretical description of novel spin-orbit torque components emerging in two-dimensional Dirac materials with broken inversion symmetry. In contrast to usual metallic interfaces where field-like and damping-like torque components are competing, we find that an intrinsic damping-like torque which derives from all Fermi-sea electrons can be simultaneously enhanced along with the field-like component. Additionally, hitherto overlooked torque components unique to Dirac materials, emerge from the coupling between spin and pseudospin degrees of freedom. These torques are found to be resilient to disorder and could enhance the magnetic switching performance of nearby magnets

Ethnography of Language Planning and Policy

A decade ago, Hornberger & Johnson proposed that the ethnography of language planning and policy (ELPP) offers a useful way to understand how people create, interpret, and at times resist language policy and planning (LPP). They envisioned ethnographic investigation of layered LPP ideological and implementational spaces, taking up Hornberger\u27s plea five years earlier for language users, educators, and researchers to fill up and wedge open ideological and implementational spaces for multiple languages, literacies, identities, and practices to flourish and grow rather than dwindle and disappear. With roots going back to the 1980s and 1990s, ethnographic research in LPP had been gathering momentum since the turn of the millennium. This review encompasses selected ethnographic LPP research since 2000, exploring affordances and constraints of this research in yielding comparative and cumulative findings on how people interpret and engage with LPP initiatives. We highlight how common-sense wisdom about the perennial gap between policy and practice is given nuance through ethnographic research that identifies and explores intertwining dynamics of top-down and bottom-up LPP activities and processes, monoglossic and heteroglossic language ideologies and practices, potential equality and actual inequality of languages, and critical and transformative LPP research paradigms

Electrical characterization of atomic-layer-deposited hafnium oxide films from hafnium tetrakis(dimethylamide) and water/ozone: Effects of growth temperature, oxygen source, and postdeposition annealing

The electrical properties of HfO2-based metal-insulator- semiconductor capacitors have been systematically investigated by means of I-V and C-V characteristics, admittance spectroscopy, deep level transient spectroscopy, conductance transient, and flat band voltage transient techniques. Attention is also given to the study of the temperature dependence of the leakage current. HfO2 films were grown on p-type silicon substrates by atomic layer deposition using hafnium tetrakis(dimethylamide) as hafnium precursor, and ozone or water as oxygen precursors. The growth temperature ranged from 150 to 350 °C. Low growth temperatures prevent decomposition and high growth rate, as well as high contamination levels. As a result, the leakage current is lower for lower deposition temperatures. Some of the deposited samples were submitted to a postdeposition annealing at 650 °C in N2 atmosphere, showing a decrease in the leakage current and an increase in the equivalent oxide thickness (EOT), whereas interfacial state density increases and defect density inside the dielectric bulk decreases. Regarding dielectric reliability, in our experimental conditions, HfO 2 layers grown at 150 °C exhibit the largest EOT and breakdown voltage. The electrical behaviour is clearly linked with structural properties, and especially with the formation of an interfacial layer between the HfO 2 layer and the silicon substrate, as well as with the presence of several impurities. © 2013 American Vacuum Society.Peer Reviewe

Colliding AdS gravitational shock waves in various dimensions and holography

The formation of marginally trapped surfaces in the off-center collision of two shock waves on AdS_D (with D=4,5,6,7 and 8) is studied numerically. We focus on the case when the two waves collide with nonvanishing impact parameter while the sources are located at the same value of the holographic coordinate. In all cases a critical value of the impact parameter is found above which no trapped surface is formed. The numerical results show the existence of a simple scaling relation between the critical impact parameter and the energy of the colliding waves. Using the isometries of AdS_D we relate the solutions obtained to the ones describing the collision of two waves with a purely holographic impact parameter. This provides a gravitational dual for the head-on collision of two lumps of energy of unequal size.Comment: 25 pages, 11 figures. v2: minor changes, typos corrected. To appear in JHE

Bioprinting as a food production technique: Conceptual and ethical aspects, advantages and disadvantages, and applications

3D bioprinters present techniques that have various applications in the food industry. For this reason, this work aims to compile and review various research works focused on the utilities and advantages of this type of machinery. Where we first mention the basis of these bioprinting techniques and then proceed to highlight the bioethical issues that surround their application in the food industry, analyze the current advantages and disadvantages, the user that has been given in the production of food for astronauts, and also mention some of the research that has been taking place in Latin America and the world. The greatest advantage of 3D bioprinting of food is the speed of production compared to traditional manufacturing methods, allowing one to obtain food with various geometric shapes; it allows control of the nutritional value, and the texture of the product, reduces environmental pollution and has the advantage of being able to take advantage of the greater performance of the materials required for production. Additionally, this technology is considered an alternative production technique that will be used to solve the problem of feeding in places of scarce resources such as space and areas not suitable for animal husbandry

Accelerated detectors in Dirac vacuum: the effects of horizon fluctuations

We consider an Unruh-DeWitt detector interacting with a massless Dirac field. Assuming that the detector is moving along an hyperbolic trajectory, we modeled the effects of fluctuations in the event horizon using a Dirac equation with random coefficients. First, we develop the perturbation theory for the fermionic field in a random media. Further we evaluate corrections due to the randomness in the response function associated to different model detectors.Comment: 19 pages, 1 figur

Energy levels distribution in supersaturated silicon with titanium for photovoltaic applications

In the attempt to form an intermediate band in the bandgap of silicon substrates to give it the capability to absorb infrared radiation, we studied the deep levels in supersaturated silicon with titanium. The technique used to characterize the energy levels was the thermal admittance spectroscopy. Our experimental results showed that in samples with titanium concentration just under Mott limit there was a relationship among the activation energy value and the capture cross section value. This relationship obeys to the well known Meyer-Neldel rule, which typically appears in processes involving multiple excitations, like carrier capture/emission in deep levels, and it is generally observed in disordered systems. The obtained characteristic Meyer-Neldel parameters were Tmn = 176 K and kTmn = 15 meV. The energy value could be associated to the typical energy of the phonons in the substrate. The almost perfect adjust of all experimental data to the same straight line provides further evidence of the validity of the Meyer Neldel rule, and may contribute to obtain a deeper insight on the ultimate meaning of this phenomenon. (C) 2015 AIP Publishing LLC