Spin-flip Effects in the Mesoscopic Spin-Interferometer

We investigate the properties of the electron spin-transmission through an Aharonov-Bohm interferometer with an embedded multilevel quantum dot containing magnetic impurities. A suitable formalism is developed. The amplitude and the phase of the flip- and nonflip-transmittance are calculated numerically as function of the magnetic field and the gate potential applied on the dot. The effects induced by the exchange interaction to spin-dependent magnetoconductance fluctuations and transmittance phase are shown.Comment: 10 pages, 9 figure

Coulomb effects on the transport properties of quantum dots in strong magnetic field

We investigate the transport properties of quantum dots placed in strong magnetic field using a quantum-mechanical ' approach based on the 2D tight-binding Hamiltonian with direct Coulomb interaction and the Landauer-B\"{u}ttiker (LB) formalism. The electronic transmittance and the Hall resistance show Coulomb oscillations and also prove multiple addition processes. We identify this feature as the 'bunching' of electrons observed in recent experiments and give an elementary explanation in terms of spectral characteristics of the dot. The spatial distribution of the added electrons may distinguish between edge and bulk states and it has specific features for bunched electrons. The dependence of the charging energy on the number of electrons is discussed for strong and vanishing magnetic field. The crossover from the tunneling to quantum Hall regime is analyzed in terms of dot-lead coupling.Comment: 17 pages,8 figures,Revtex,submitted to Physical Review

Kinetic Energy Density Study of Some Representative Semilocal Kinetic Energy Functionals

There is a number of explicit kinetic energy density functionals for non-interacting electron systems that are obtained in terms of the electron density and its derivatives. These semilocal functionals have been widely used in the literature. In this work we present a comparative study of the kinetic energy density of these semilocal functionals, stressing the importance of the local behavior to assess the quality of the functionals. We propose a quality factor that measures the local differences between the usual orbital-based kinetic energy density distributions and the approximated ones, allowing to ensure if the good results obtained for the total kinetic energies with these semilocal functionals are due to their correct local performance or to error cancellations. We have also included contributions coming from the laplacian of the electron density to work with an infinite set of kinetic energy densities. For all the functionals but one we have found that their success in the evaluation of the total kinetic energy are due to global error cancellations, whereas the local behavior of their kinetic energy density becomes worse than that corresponding to the Thomas-Fermi functional.Comment: 12 pages, 3 figure

Local Behavior of the First-Order Gradient Correction to the Thomas-Fermi Kinetic Energy Functional

The first order gradient correction to the Thomas-Fermi functional, proposed by Haq, Chattaraj and Deb (Chem. Phys. Lett. vol. 81, 8031, 1984) has been studied by evaluating both the total kinetic energy and the local kinetic energy density. For testing the kinetic energy density we evaluate its deviation from an exact result through a quality factor, a parameter that reflects the quality of the functionals in a better way than their relative errors. The study is performed on two different systems: light atoms (up to Z=18) and a noninteracting model of fermions confined in a Coulombic-type potential. It is found than this approximation gives very low relative errors and a better local behavior than any of the usual generalized gradient approximation semilocal kinetic density functionals.Comment: 7 pages, 2 tables, 4 figure

The Integrated Renovation of High-Rise Hotels on the Spanish Mediterranean Coast

In terms of construction and energy efficiency, Spain has one of the highest indexes of obsolete buildings among the developed countries. In the case of high-rise hotel buildings, this problem is further added to by the low levels of safety in the case of fire. The development of tourism in the 1950s and 60s led to the construction of a large number of high-rise hotels with 30+ floors. Initially, they conformed to lax, undemanding regulations regarding fire resistance in their structural components, fire escape routes, protected staircases, and so on. The requirements of today’s regulations in this field, contained in the Basic SI Technical Building Code Document, often make the renovation of these buildings an impossible task. Installing specially protected staircases can entail traumatic modifications that are sometimes unviable due to structural conditions or economic considerations. Furthermore, the building’s energy efficiency and CO2 emissions do not correspond to environmentally-friendly practices. This paper examines the above questions with regard to the Hotel Tryp Gran Sol in Alicante, Spain. The hotel is 97 m high and has 31 floors. The integrated renovation of the hotel requires serious reflection upon the building’s global response to personal safety, its envelope components and its air conditioning. Architectural solutions and the building’s economic viability for future exploitation as an important element in the building’s life cycle assessment (LCA) are discussed

Magnetization and Level Statistics at Quantum Hall Liquid-Insulator Transition in the Lattice Model

Statistics of level spacing and magnetization are studied for the phase diagram of the integer quantum Hall effect in a 2D finite lattice model with Anderson disorder.Comment: 4 pages, 6 figure

Improving CO2 methanation performance by distributed feeding in a Ni-Mn catalyst fixed bed reactor

It has been successfully demonstrated the effect of feeding reactants in distributed manner for the reaction of methanation of CO2. This operation mode has improved not only the selectivity towards CH4, but also the overall process performance. A fixed bed reactor, loaded with Ni-Mn based catalyst, was operated co-feeding both CO2 and H2, but alternatively feeding one of them through several lateral inlets. Preserving the same global W/FCO2 ratio, the side distribution of CO2 allowed to clearly increase the activity of the process (e.g., at 375 °C, the conversion with distributed feeding was around 35% higher than that for the conventional one: XCO2 = 0.12 vs. XCO2 = 0.09). Furthermore, a substantially lower selectivity towards non-desired CO was obtained at any conversion level (e.g., SCO = 0.45 vs. SCO = 0.70, when XCO2 = 0.10). In addition, a more homogeneous temperature profile could be achieved in the bed without increasing the severity of hot spots appearance. On the contrary, side distribution of H2 always led to similar or worse results than for the conventional co-feeding configuration

Phosphate-activated cyclin-dependent kinase stabilizes G1 cyclin to trigger cell cycle entry

G1 cyclins, in association with a cyclin-dependent kinase (CDK), are universal activators of the transcriptional G1-S machinery during entry into the cell cycle. Regulation of cyclin degradation is crucial for coordinating progression through the cell cycle, but the mechanisms that modulate cyclin stability to control cell cycle entry are still unknown. Here, we show that a lack of phosphate downregulates Cln3 cyclin and leads to G1 arrest in Saccharomyces cerevisiae. The stability of Cln3 protein is diminished in strains with low activity of Pho85, a phosphate-sensing CDK. Cln3 is an in vitro substrate of Pho85, and both proteins interact in vivo. More interestingly, cells that carry a CLN3 allele encoding aspartic acid substitutions at the sites of Pho85 phosphorylation maintain high levels of Cln3 independently of Pho85 activity. Moreover, these cells do not properly arrest in G1 in the absence of phosphate and they die prematurely. Finally, the activity of Pho85 is essential for accumulating Cln3 and for reentering the cell cycle after phosphate refeeding. Taken together, our data indicate that Cln3 is a molecular target of the Pho85 kinase that is required to modulate cell cycle entry in response to environmental changes in nutrient availability. © 2013, American Society for Microbiology.S. Hernández received a postgraduate Junior Faculty fellowship from the UIC and l'Obra Social la Caixa. This work was supported by grants from Ministerio de Ciencia e Innovación of the Spanish government (BFU 2009-09278)Peer Reviewe