A conjugate for the Bargmann representation

In the Bargmann representation of quantum mechanics, physical states are mapped into entire functions of a complex variable z*, whereas the creation and annihilation operators $\hat{a}^\dagger$ and $\hat{a}$ play the role of multiplication and differentiation with respect to z*, respectively. In this paper we propose an alternative representation of quantum states, conjugate to the Bargmann representation, where the roles of $\hat{a}^\dagger$ and $\hat{a}$ are reversed, much like the roles of the position and momentum operators in their respective representations. We derive expressions for the inner product that maintain the usual notion of distance between states in the Hilbert space. Applications to simple systems and to the calculation of semiclassical propagators are presented.Comment: 15 page

Purinergic P2 receptors trigger adenosine release leading to adenosine A2A receptor activation and facilitation of long-term potentiation in rat hippocampal slices

Electrophysiological recordings were used to investigate the effects of ATP analogues on [theta]-burst-induced long-term potentiation (LTP) in rat hippocampal slices. [alpha],[beta]-Methylene ATP ([alpha],[beta]-MeATP; 20 [mu]M) decreased LTP from 36±9% to 17±5%, an effect prevented by adenosine A1 receptor blockade in accordance with the localised catabolism of ATP analogues into adenosine, leading to adenosine A1 receptor activation. Thus, to probe the role of extracellular ATP, all experiments were performed with the A1 receptor selective antagonist, 1,3-dipropyl-8-cyclopentylxanthine (50 nM). In these conditions, [alpha],[beta]-MeATP or 5'-adenylylimido-diphosphate ([beta],[gamma]-ImATP; 20 [mu]M) facilitated LTP by 120%, an effect prevented by the P2 receptor antagonists, pyridoxalphosphate-6-azophenyl-2'-4'-disulphonic acid (PPADS; 20 [mu]M) or suramin (75 [mu]M), as well as by the P2X1/3-selective antagonist 8-(benzamido)naphthalene-1,3,5-trisulfonate (10 [mu]M). The facilitations of LTP by either [alpha],[beta]-MeATP or [beta],[gamma]-ImATP (20 [mu]M) were also prevented by both 4-(2-[7-amino-2-(2-furyl(1,2,4)-triazolo(2,3a)-(1,3,5)triazin-5-yl-amino]ethyl)phenol (50 nM) or 7-2(-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo[1,5-c] pyrimidine (50 nM), antagonists of facilitatory adenosine A2A receptors, were occluded by the A2A receptor agonist, CGS 21680 (10 nM) and were prevented by the protein kinase C inhibitor, chelerythrine (6 [mu]M) and unaffected by the protein kinase A inhibitor, H89 (1 [mu]M). Furthermore, [beta],[gamma]-ImATP (20 [mu]M) enhanced [3H]adenosine outflow from rat hippocampal slices by nearly 150%, an effect prevented by PPADS (20 [mu]M) or suramin (75 [mu]M). The adenosine transport inhibitors, nitrobenzylthioinosine (5 [mu]M) and dipyridamole (10 [mu]M) also prevented [beta],[gamma]-ImATP (20 [mu]M)-induced [3H]adenosine outflow and facilitation of LTP. These results suggest that ATP analogues facilitate LTP through P2 receptor activation that mainly triggers adenosine release leading to the activation of adenosine A2A receptors.http://www.sciencedirect.com/science/article/B6T0F-49SFDNY-1/1/bd15c287ddd50f5af9c1be35dcb9227

Five-Dimensional QED, Muon Pair Production and Correction to the Coulomb Potential

We consider QED in five dimensions in a configuration where matter is localized on a 3-brane while foton propagates in the bulk. The idea is to investigate the effects of the Kaluza-Klein modes of the photon in the relativistic regime, but in low energy, and in the nonrelativistic regime. In the relativistic regime, we calculate the cross section for the reaction $e^+ + e^- \to \mu^+ + \mu^-$. We compare our theoretical result with a precise measurement of this cross section at $\sqrt{s}=57.77$ GeV. As result, we extract a lower bound on the size of the extra dimension. In the nonrelativistic regime, we derive the contribution for the Coulomb potential due to the whole tower of the Kaluza-Klein excited modes of the photon. We use the modified potential to calculate the Rutherford scattering differential cross section.Comment: minor changes, three new refs. added, to appear in IJMP

Comportamento agronomico de cultivares e linhagens de arroz irrigado no estado do Piaui.

bitstream/item/97420/1/PAND550001.pd

Balanço de nutrientes em cultivos de hortaliças sob manejo orgânico.

bitstream/CNPAB-2010/27146/1/cot021.pd

Edge phonons in black phosphorus

Exfoliated black phosphorus has recently emerged as a new two-dimensional crystal that, due to its peculiar and anisotropic crystalline and electronic band structures, may have potentially important applications in electronics, optoelectronics and photonics. Despite the fact that the edges of layered crystals host a range of singular properties whose characterization and exploitation are of utmost importance for device development, the edges of black phosphorus remain poorly characterized. In this work, the atomic structure and the behavior of phonons near different black phosphorus edges are experimentally and theoretically studied using Raman spectroscopy and density functional theory calculations. Polarized Raman results show the appearance of new modes at the edges of the sample, and their spectra depend on the atomic structure of the edges (zigzag or armchair). Theoretical simulations confirm that the new modes are due to edge phonon states that are forbidden in the bulk, and originated from the lattice termination rearrangements.Comment: 15 pages, 4 figure