Persistent Currents in Small, Imperfect Hubbard Rings

We have done a study with small, imperfect Hubbard rings with exact diagonalization. The results for few-electron rings show, that the imperfection, whether localized or not, nearly always decrease, but can also \emph{increase} the persistent current, depending on the character of the imperfection and the on-site interaction. The calculations are generally in agreement with more specialized studies. In most cases the electron spin plays an important role.Comment: 6 pages, 4 figure

Transcriptome profiling of grapevine seedless segregants during berry development reveals candidate genes associated with berry weight

Indexación: Web of Science; PubMedBackground Berry size is considered as one of the main selection criteria in table grape breeding programs. However, this is a quantitative and polygenic trait, and its genetic determination is still poorly understood. Considering its economic importance, it is relevant to determine its genetic architecture and elucidate the mechanisms involved in its expression. To approach this issue, an RNA-Seq experiment based on Illumina platform was performed (14 libraries), including seedless segregants with contrasting phenotypes for berry weight at fruit setting (FST) and 6–8 mm berries (B68) phenological stages. Results A group of 526 differentially expressed (DE) genes were identified, by comparing seedless segregants with contrasting phenotypes for berry weight: 101 genes from the FST stage and 463 from the B68 stage. Also, we integrated differential expression, principal components analysis (PCA), correlations and network co-expression analyses to characterize the transcriptome profiling observed in segregants with contrasting phenotypes for berry weight. After this, 68 DE genes were selected as candidate genes, and seven candidate genes were validated by real time-PCR, confirming their expression profiles. Conclusions We have carried out the first transcriptome analysis focused on table grape seedless segregants with contrasting phenotypes for berry weight. Our findings contributed to the understanding of the mechanisms involved in berry weight determination. Also, this comparative transcriptome profiling revealed candidate genes for berry weight which could be evaluated as selection tools in table grape breeding programs.http://bmcplantbiol.biomedcentral.com/articles/10.1186/s12870-016-0789-

Quantum Rings in Electromagnetic Fields

This is the author accepted manuscript. The final version is available from Springer via the DOI in this recordThis chapter is devoted to optical properties of so-called Aharonov-Bohm quantum rings (quantum rings pierced by a magnetic flux resulting in AharonovBohm oscillations of their electronic spectra) in external electromagnetic fields. It studies two problems. The first problem deals with a single-electron AharonovBohm quantum ring pierced by a magnetic flux and subjected to an in-plane (lateral) electric field. We predict magneto-oscillations of the ring electric dipole moment. These oscillations are accompanied by periodic changes in the selection rules for inter-level optical transitions in the ring allowing control of polarization properties of the associated terahertz radiation. The second problem treats a single-mode microcavity with an embedded Aharonov-Bohm quantum ring which is pierced by a magnetic flux and subjected to a lateral electric field. We show that external electric and magnetic fields provide additional means of control of the emission spectrum of the system. In particular, when the magnetic flux through the quantum ring is equal to a half-integer number of the magnetic flux quanta, a small change in the lateral electric field allows for tuning of the energy levels of the quantum ring into resonance with the microcavity mode, thus providing an efficient way to control the quantum ring-microcavity coupling strength. Emission spectra of the system are discussed for several combinations of the applied magnetic and electric fields

Use of SMS texts for facilitating access to online alcohol interventions: a feasibility study

A41 Use of SMS texts for facilitating access to online alcohol interventions: a feasibility study In: Addiction Science & Clinical Practice 2017, 12(Suppl 1): A4

Electron-hole Transitions In Self-assembled Inas/gaas Quantum Dots: Effects Of Applied Magnetic Fields And Hydrostatic Pressure

A theoretical study of the effects of applied magnetic fields and hydrostatic pressure on the electron-hole transition energies in self-assembled InAs/GaAs quantum dots is presented. The effective-mass approximation and a model of a cylindrical-shaped quantum dot with in-plane parabolic potential have been used to describe the InAs/GaAs quantum dots. Present theoretical results are in quite good agreement with experimental measurements of the magnetic field and pressure dependence of the exciton transition energies in InAs/GaAs self-assembled quantum dots. © 2005 Elsevier Ltd. All rights reserved.363-6231233Itskevich, I.E., Henini, M., Carmona, H.A., Eaves, L., Main, P.C., Maude, D.K., Portal, J.C., (1997) Appl. Phys. Lett., 70, p. 505Itskevich, I.E., Lyapin, S.G., Troyan, I.A., Klipstein, P.C., Eaves, L., Main, P.C., Henini, M., (1998) Phys. Rev. B, 58, pp. R4250Barticevic, Z., Pacheco, M., Claro, F., (1995) Phys. Rev. B, 51, p. 14414Pacheco, M., Barticevic, Z., (1999) J. Phys.: Condens. Matter, 11, p. 1079Barticevic, Z., Pacheco, M., Duque, C.A., Oliveira, L.E., (2002) J. Phys.: Condens. Matter, 14, p. 1021Barticevic, Z., Pacheco, M., Duque, C.A., Oliveira, L.E., (2002) J. Appl. Phys., 92, p. 1227Yu, P.Y., Cardona, M., (1998) Fundamentals of Semiconductors, , second ed. Springer BerlinCusack, M.A., Briddon, P.R., Jaros, M., (1996) Phys. Rev. B, 54, pp. R2300Cusack, M.A., Briddon, P.R., Jaros, M., (1997) Phys. Rev. B, 56, p. 4047Adler, F., Geiger, M., Bauknecht, A., Scholz, F., Schweizer, H., Pilkuhn, M.H., Ohnesorge, B., Forchel, A., (1996) J. Appl. Phys., 80, p. 4019Elabsy, A.M., (1993) Physica Scripta, 48, p. 376Stier, O., Grundmann, M., Bimberg, D., (1999) Phys. Rev. B, 59, p. 5688Su-Huai, W., Zunger, A., (1999) Phys. Rev. B, 60, p. 5404Ma, B.S., Wang, X.D., Su, F.H., Fang, Z.L., Ding, K., Niu, Z.C., Li, G.H., (2004) J. Appl. Phys., 95, p. 933Pacheco, M., Barticevic, Z., (2001) Phys. Rev. B, 64, p. 033406Barticevic, Z., Pacheco, M., Duque, C.A., Oliveira, L.E., (2003) Phys. Rev. B, 68, p. 07331

Effects of applied magnetic fields and hydrostatic pressure on the optical transitions in self-assembled InAs/GaAs quantum dots

A theoretical study of the photoluminescence peak energies in InAs self-assembled quantum dots embedded in a GaAs matrix in the presence of magnetic fields applied perpendicular to the sample plane is performed. The effective mass approximation and a parabolic potential cylinder-shaped model for the InAs quantum dots are used to describe the effects of magnetic field and hydrostatic pressure on the correlated electron-hole transition energies. Theoretical results are found in quite good agreement with available experimental measurements for InAs/GaAs self-assembled quantum dots.1861877188

Magnetoexcitons in nanostructures exhibiting cylindrical symmetry

The problem of an exciton in the cylindrical nanostructure exposed to an external static magnetic field is investigated. The theoretical model assumes anisotropic masses which are different inside and outside the nanostructure. The confinement potential has finite value at the boundaries and magnetic field is parallel to the axis of the cylinder. The screened Coulomb interaction between an electron and a hole is assumed. The consistent mathematical procedure is developed to calculate the magnetoexciton eigenfunctions and eigenenergies. Our method applies to the systems exhibiting cylindrical symmetry where, due to confinement effects accompanied by the e-h Coulomb interaction, the separation of relative- and center-of-mass motion is not possible. Numerical calculations have been performed for the quantum disk, the cylinder and the quantum rod. The magnetic field dependent energy spectrum and corresponding wave functions, expressed in terms of known one-particle electron and hole eigenfunctions, are calculated. Additionally, we point out the different role of Coulomb interaction in every case