Non-orientable surface-plus-one-relation groups

Recently Dicks–Linnell determined the L2-Betti numbers of the orientable surface-plus-one-relation groups, and their arguments involved some results that were obtained topologically by Hempel and Howie. Using algebraic arguments, we now extend all these results of Hempel and Howie to a larger class of two-relator groups, and we then apply the extended results to determine the L2-Betti numbers of the non-orientable surface-plus-one-relation group

Financing Transitional Jobs Programs

Presentation about financing transitional jobs programs. Presented at the 2008 NTJN Conference

Lower and upper bounds for the first eigenvalue of nonlocal diffusion problems in the whole space

We find lower and upper bounds for the first eigenvalue of a nonlocal diffusion operator of the form T(u) = - \int_{\rr^d} K(x,y) (u(y)-u(x)) \, dy. Here we consider a kernel $K(x,y)=\psi (y-a(x))+\psi(x-a(y))$ where $\psi$ is a bounded, nonnegative function supported in the unit ball and $a$ means a diffeomorphism on \rr^d. A simple example being a linear function $a(x)= Ax$. The upper and lower bounds that we obtain are given in terms of the Jacobian of $a$ and the integral of $\psi$. Indeed, in the linear case $a(x) = Ax$ we obtain an explicit expression for the first eigenvalue in the whole \rr^d and it is positive when the the determinant of the matrix $A$ is different from one. As an application of our results, we observe that, when the first eigenvalue is positive, there is an exponential decay for the solutions to the associated evolution problem. As a tool to obtain the result, we also study the behaviour of the principal eigenvalue of the nonlocal Dirichlet problem in the ball $B_R$ and prove that it converges to the first eigenvalue in the whole space as $R\to \infty$

Multinationals, R&D and productivity: Evidence for UK Manufacturing firms

In this study we analyze multinationality (domestic-based firms vs. multinationals) and foreignness (foreign vs. domestic firms) effects in the returns of R&D to productivity. We follow a two-step strategy. In the first step, we consistently estimate firm’s productivity by GMM and numerically compute the sample distribution of the R&D returns. In the second step, we use stochastic dominance techniques to make inferences on the multinationality and foreignness effects. Results for a panel of UK manufacturing firms suggest that multinationality and foreignness effects operate in an opposite way: whilst the multinationality effect enhances R&D returns, the foreignness diminishes them.multinationals, foreignness, R&D, productivity

AI delivers Michaelis constants as fuel for genome-scale metabolic models

Michaelis constants (Km) are essential to predict the catalytic rate of enzymes, but are not widely available. A new study in PLOS Biology uses artificial intelligence (AI) to accurately predict Km on a proteome-wide scale, paving the way for dynamic, genome-wide modeling of metabolism

Efficient Rotating Frame Simulation in Turbomachinery

This paper deals with the simulation of steady flows in tur- bomachinery. Two approaches are proposed, the first one is the classical multiple-rotating frame method (MRF) by multi- zone approach where the different zones are separated by non- overlapping interfaces and solved independently. Since each zone is loaded separately, a transferring system should be prop- erly implemented at the interface boundaries. Two techniques are considered, in the first one the conservative variables are in- terpolated between zones while in the second one the fluxes are transferred through the interfaces. The other proposed approach is a new version of the MRF using a virtual interface (VMRF). This is a simplified of the pre- vious one where the interfaces are created virtually at the solver level, rendering the method easy to implement especially for edge-based numerical schemes, and avoiding any re-meshing in case one needs to change interface position, shape or simply re- move or add new one. Finally, numerical tests are performed to demonstrate the efficiency of the proposed methods by compari- son with commercial codes (ANSYS FLUENT)

Application of photoluminescence and electroluminescence techniques to the characterization of intermediate band solar cells

The intermediatebandsolarcell (IBSC) is a photovoltaic device with a theoretical conversion efficiency limit of 63.2%. In recent years many attempts have been made to fabricate an intermediateband material which behaves as the theory states. One characteristic feature of an IBSC is its luminescence spectrum. In this work the temperature dependence of the photoluminescence (PL) and electroluminescence (EL) spectra of InAs/GaAs QD-IBSCs together with their reference cell have been studied. It is shown that EL measurements provide more reliable information about the behaviour of the IB material inside the IBSC structure than PL measurements. At low temperatures, the EL spectra are consistent with the quasi-Fermi level splits described by the IBSC model, whereas at room temperature they are not. This result is in agreement with previously reported analysis of the quantum efficiency of the solarcell

Self-consistent 3D radiative MHD simulations of coronal rain formation and evolution

Context. Coronal rain consists of cool and dense plasma condensations formed in coronal loops as a result of thermal instability. Aims. Previous numerical simulations of thermal instability and coronal rain formation have relied on the practice of artificially adding a coronal heating term to the energy equation. To reproduce large-scale characteristics of the corona, the use of more realistic coronal heating prescription is necessary. Methods. We analysed coronal rain formation and evolution in a three-dimensional radiative magnetohydrodynamic simulation spanning from convection zone to corona which is self-consistently heated by magnetic field braiding as a result of convective motions. Results. We investigate the spatial and temporal evolution of energy dissipation along coronal loops which become thermally unstable. Ohmic dissipation in the model leads to the heating events capable of inducing sufficient chromospheric evaporation into the loop to trigger thermal instability and condensation formation. The cooling of the thermally unstable plasma occurs on timescales that are comparable to the duration of the individual impulsive heating events. The impulsive heating has sufficient duration to trigger thermal instability in the loop but does not last long enough to lead to coronal rain limit cycles. We show that condensations can either survive and fall into the chromosphere or be destroyed by strong bursts of Joule heating associated with a magnetic reconnection events. In addition, we find that condensations can also form along open magnetic field lines. Conclusions. We modelled, for the first time, coronal rain formation in a self-consistent 3D radiative magnetohydrodynamic simulation, in which the heating occurs mainly through the braiding and subsequent Ohmic dissipation of the magnetic field. The heating is stratified enough and lasts for long enough along specific field lines to produce the necessary chromospheric evaporation that triggers thermal instability in the corona

Irrigation efficiency simulation for common bean during dry season, in the municipality of Goiânia, Goiás.

Goiás State is considered the major common beans producer in the autumn/winter season. In this season, the common beans production is fully irrigated by Center Pivot. However, due to the water scarcity water, the water dispute among human consumption, power generation, industries and agriculture is increasing. Then, it is important to optimize their consumption in the agriculture. Crop models are excellent tools for that and were used in this study to simulate the irrigation efficiency during the winter season for two cultivars, Pérola and BRS Radiante. Five planting dates from April to August and five irrigation amounts (10, 15, 20, 25 and 30 mm) applied when the soil water content reaches 50% of field capacity (CC) were considered. For cultivar Pérola, longer cycle, the best irrigation efficiency was obtained at the end of planting season, in the month of August, for the fixed irrigation amounts of 20 and 25 mm respectively. In the other hand, for the short cycle cultivar, BRS Radiante, the best irrigation efficiency was obtained only at the begin of planting date season, April