HEA/JISC Open Educational Resources case study: pedagogical development from OER practice: research ethics OER: can they be 'radically repurposed and remixed'?

This case study provides guidance on discovering, reusing and repurposing of Open Educational Resources (OER). It is presented within the context of research ethics OER for higher education learning and teaching and, together with the OER guidance, provides examples of OER found for this subject area

Terrestrial carbon sinks for the United States Predicted from MODIS satellite data and ecosystem modeling

A simulation model based on satellite observations of monthly vegetation cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate monthly carbon fluxes in terrestrial ecosystems of the conterminous United States over the period 2001-04. Predicted net ecosystem production (NEP) flux for atmospheric CO2 in the United States was estimated as annual net sink of about +0.2 Pg C in 2004. Regional climate patterns were reflected in the predicted annual NEP flux from the model, which showed extensive carbon sinks in ecosystems of the southern and eastern regions in 2003-04, and major carbon source fluxes from ecosystems in the Rocky Mountain and Pacific Northwest regions in 2003-04. As demonstrated through tower site comparisons, net primary production (NPP) modeled with monthly MODIS enhanced vegetation index (EVI) inputs closely resembles both the measured high- and low-season carbon fluxes. Modeling results suggest that the capacity of the NASA Carnegie Ames Stanford Approach (CASA) model to use 8-km resolution MODIS EVI data to predict peak growing season uptake rates of CO2 in irrigated croplands and moist temperate forests is strong

Effect of well-width on the electro-optical properties of a quantum well

We record photoreflectance from Ge/GeSi modulation doped quantum wells possessing $10^4$ V/cm perpendicular electric fields. Qualitatively very different spectra are obtained from samples of well-width 100 \AA and 250 \AA. Comparing the wavefunctions calculated from an $8 \times 8$ \textbf{k.p} theory, we find that while they remain confined in the narrower 100 \AA QW, the electric field causes them to tunnel into the forbidden gap in the 250 \AA\ well. This implies that the samples should show a transition from the quantum confined Franz-Keldysh effect to the bulk-like Franz-Keldysh effect. Close to the band-edge where Franz-Keldysh effects are important, simulated photoreflectance spectra reproduce the essential features of the experiment, without any adjustable parameters.Comment: 8 pages, 8 figures. Submitted to Phys. Rev.

Thermal-radiation-induced nonequilibrium carriers in an intrinsic graphene

We examine an intrinsic graphene connected to the phonon thermostat at temperature T under irradiation of thermal photons with temperature T_r, other than T. The distribution of nonequilibrium electron-hole pairs was obtained for the cases of low and high concentration of carriers. For the case when the interparticle scattering is unessential, the distribution function is determined by the interplay of intraband relaxation of energy due to acoustic phonons and interband radiative transitions caused by the thermal radiation. When the Coulomb scattering dominates, then the quasi-equilibrium distribution with effective temperature and non-equilibrium concentration, determined through balance equations, is realized. Due to the effect of thermal radiation with temperature $T_r\neq T$ concentration and conductivity of carriers in graphene modify essentially. It is demonstrated, that at $T_r>T$ the negative interband absorption, caused by the inversion of carriers distribution, can occur, i.e. graphene can be unstable under thermal irradiation.Comment: 5 pages, 4 figure

Quantum spin liquids and the metal-insulator transition in doped semiconductors

We describe a new possible route to the metal-insulator transition in doped semiconductors such as Si:P or Si:B. We explore the possibility that the loss of metallic transport occurs through Mott localization of electrons into a quantum spin liquid state with diffusive charge neutral "spinon" excitations. Such a quantum spin liquid state can appear as an intermediate phase between the metal and the Anderson-Mott insulator. An immediate testable consequence is the presence of metallic thermal conductivity at low temperature in the electrical insulator near the metal-insulator transition. Further we show that though the transition is second order the zero temperature residual electrical conductivity will jump as the transition is approached from the metallic side. However the electrical conductivity will have a non-monotonic temperature dependence that may complicate the extrapolation to zero temperature. Signatures in other experiments and some comparisons with existing data are made.Comment: 4 pages text + 3 pages Appendices, 3 Figures; v2 - References Adde

Exploring inside-out Doppler tomography: magnetic cataclysmic variables

Context. Doppler tomography of magnetic cataclysmic variables is a valuable tool for the interpretation of the complex spectroscopic emission line profiles observed for these systems

Controlling chaos in spatially extended beam-plasma system by the continuous delayed feedback

In present paper we discuss the control of complex spatio-temporal dynamics in a {spatially extended} non-linear system (fluid model of Pierce diode) based on the concepts of controlling chaos in the systems with few degrees of freedom. A presented method is connected with stabilization of unstable homogeneous equilibrium state and the unstable spatio-temporal periodical states analogous to unstable periodic orbits of chaotic dynamics of the systems with few degrees of freedom. We show that this method is effective and allows to achieve desired regular dynamics chosen from a number of possible in the considered system.Comment: 12 pages, 12 figure