Eisenstein Series and String Thresholds

We investigate the relevance of Eisenstein series for representing certain $G(Z)$-invariant string theory amplitudes which receive corrections from BPS states only. $G(Z)$ may stand for any of the mapping class, T-duality and U-duality groups $Sl(d,Z)$, $SO(d,d,Z)$ or $E_{d+1(d+1)}(Z)$ respectively. Using $G(Z)$-invariant mass formulae, we construct invariant modular functions on the symmetric space $K\backslash G(R)$ of non-compact type, with $K$ the maximal compact subgroup of $G(R)$, that generalize the standard non-holomorphic Eisenstein series arising in harmonic analysis on the fundamental domain of the Poincar\'e upper half-plane. Comparing the asymptotics and eigenvalues of the Eisenstein series under second order differential operators with quantities arising in one- and $g$-loop string amplitudes, we obtain a manifestly T-duality invariant representation of the latter, conjecture their non-perturbative U-duality invariant extension, and analyze the resulting non-perturbative effects. This includes the $R^4$ and $R^4 H^{4g-4}$ couplings in toroidal compactifications of M-theory to any dimension $D\geq 4$ and $D\geq 6$ respectively.Comment: Latex2e, 60 pages; v2: Appendix A.4 extended, 2 refs added, thms renumbered, plus minor corrections; v3: relation (1.7) to math Eis series clarified, eq (3.3) and minor typos corrected, final version to appear in Comm. Math. Phys; v4: misprints and Eq C.13,C.24 corrected, see note adde

Microbially charged redox flow battery: coupling a bioelectrochemical cell with a redox flow battery

ISMET 6 - General Meeting of the International Society for Microbial Electrochemistry and TechnologyRedox flow batteries (RFB) are electrochemical systems applied in the conversion and storage of chemical energy in electricity. Red ox chemical species (in soluble form) are the main responsible for the energy storage. Quinones are electroactive molecules applied in RFB because of their chemical and physical properties. The aim of this work is to develop an innovative technology to generate and storage the energy resultant from Bioelectrochemical system (BES). The strategy outlined was coupling a BES with a RFB that present potential to combine bioenergy production and storage in a microbially charged redox flow battery. Firstly, a BES system was studied with Geobacter su/furreducens as biocatalyst to convert a quinone (2,6-anthraquinone) in its respective reduced form, acetate being the carbon source used. The BES presented current intensities around 500 mA.m·2 and power densities around 2 wm· 2. The reduction was assessed visually by a typical colour change (from yellow to dark red) and by cyclic voltammetry. Simultaneously, as a control, the 2,6-anthraquinone was electrochemically reduced applying and controlling the cathode potential where the reduction was also observed by colour change and by cyclic voltammetry. In an RFB, the quinone bioreduced in tlie BES and electrochemically reduced in the electrochemical cell were studied using potassium hexacyanoferrate as the second redox chemical species for discharging/charging cycles in the RFB as the proof of concept of the microbially charged redox flow battery. The study was performed in a 25 cm2 single red ox flow cell (RF) with a constant current density of 0.2 mA.cm2 where coulombic efficiency, voltage efficiency and energy efficiency were observed for 10 cycles.info:eu-repo/semantics/publishedVersio

Uma proposta para a identificação de tendências de pesquisa e desenvolvimento em agroinformática.

RESUMO: Neste trabalho experimenta-se a identificação semi-automática das linhas de pesquisa e desenvolvimento em agroinformática refletidas pelos principais fóruns da área. Para isso, tomaram-se as publicações textuais desses fóruns, disponíveis em formato eletrônico, e aplicou-se um processo de mineração de textos. O processo de mineração de textos foi adaptado para esse fim, para permitir o uso de vocabulário controlado da área e o julgamento subjetivo de especialistas do domínio de conhecimento mediante os resultados semi-automaticamente obtidos. Os resultados apresentados, embora parciais, nitidamente mostram que as tendências concentram-se em modelos de simulação, geoprocessamento e análise de dados, em geral, em áreas como análise de mercado e modelagem agroambiental.SBIAgro 2011

Modelling the Recoherence of Mesoscopic Superpositions in Dissipative Environments

A model is presented to describe the recently proposed experiment (J. Raimond, M. Brune and S. Haroche Phys. Rev. Lett {\bf 79}, 1964 (1997)) where a mesoscopic superposition of radiation states is prepared in a high-Q cavity which is coupled to a similar resonator. The dynamical coherence loss of such state in the absence of dissipation is reversible and can in principle be observed. We show how this picture is modified due to the presence of the environmental couplings. Analytical expressions for the experimental conditional probabilities and the linear entropy are given. We conclude that the phenomenon can still be observed provided the ratio between the damping constant and the inter-cavities coupling does not exceed about a few percent. This observation is favored for superpositions of states with large overlap.Comment: 13 pages, 6 figure

Coupling a bioelectrochemical cell with a redox flow battery for sustainable energy production and storage

Book of Abstracts of CEB Annual Meeting 2017[Excerpt] Bioelectrochemical systems (BES) are devices capable to convert chemical energy into electricity through the degradation of different organic compounds using electroactive bacteria as biocatalyst. The ability of microorganisms to form biofilms in electrode surfaces allows the transport of electrons, resultant from the oxidation of carbon sources, to an terminal electron acceptor [1]. Redox flow batteries (RFB) are electrochemical systems applied in the conversion and storage of chemical energy in electricity. Redox chemical species (in soluble form) are the main responsible for the energy storage [2]. Quinones are electroactive molecules applied in RFB because of their chemical and physical properties. The aim of this work is to develop an innovative technology to generate and storage the energy resultant from BES. The strategy outlined is coupling a BES with a RFB that present potential to combine bioenergy production and storage in a microbially charged redox flow battery. [...]info:eu-repo/semantics/publishedVersio