Intramolecular electronic energy transfer in bichromophoric macrocyclic complexes

Efficient intramolecular electronic energy transfer (EET) has been demonstrated for three novel bichromophoric compounds utilizing a macrocyclic spacer as the bridge between the electronic energy donor and acceptor fragments. As their free base forms, emission from the electronically excited donor is absent and the acceptor emission is reductively quenched via photoinduced oxidation of proximate amine lone pairs. As their Zn(II) complexes, excitation of the donor results in sensitization of the electronic acceptor emission.

Electron exchange coupling for single-donor solid-state spin qubits

Intervalley interference between degenerate conduction band minima has been shown to lead to oscillations in the exchange energy between neighboring phosphorus donor electron states in silicon [B. Koiller, X. Hu, and S. Das Sarma, Phys. Rev. Lett. 88, 027903 (2002); Phys. Rev. B 66, 115201 (2002)]. These same effects lead to an extreme sensitivity of the exchange energy on the relative orientation of the donor atoms, an issue of crucial importance in the construction of silicon-based spin quantum computers. In this article we calculate the donor electron exchange coupling as a function of donor position incorporating the full Bloch structure of the Kohn-Luttinger electron wave functions. It is found that due to the rapidly oscillating nature of the terms they produce, the periodic part of the Bloch functions can be safely ignored in the Heitler-London integrals as was done by Koiller, Hu, and Das Sarma, significantly reducing the complexity of calculations. We address issues of fabrication and calculate the expected exchange coupling between neighboring donors that have been implanted into the silicon substrate using an 15 keV ion beam in the so-called top down fabrication scheme for a Kane solid-state quantum computer. In addition, we calculate the exchange coupling as a function of the voltage bias on control gates used to manipulate the electron wave functions and implement quantum logic operations in the Kane proposal, and find that these gate biases can be used to both increase and decrease the magnitude of the exchange coupling between neighboring donor electrons. The zero-bias results reconfirm those previously obtained by Koiller, Hu, and Das Sarma.

Rates of electronic energy transfer in conformationally flexible bichromophoric macrocyclic complexes: a combined experimental and molecular modeling study

Electronic energy transfer (EET) rate constants between a naphthalene donor and anthracene acceptor in [ZnL4a](ClO4)(2) and [ZnL4b](ClO4)(2) were determined by time-resolved fluorescence where L-4a and L-4b are the trans and cis isomers of 6-((anthracen-9-yl-methyl)amino)-6,13-dimethyl-13-((naphthalen-1-yl-methyl)amino)-1,4,8,11-tetraazacyclotetradecane, respectively. These isomers differ in the relative disposition of the appended chromophores with respect to the macrocyclic plane. The trans isomer has an energy transfer rate constant (k(EET)) of 8.7 x 10(8) s(-1), whereas that of the cis isomer is significantly faster (2.3 x 10(9) s(-1)). Molecular modeling was used to determine the likely distribution of conformations in CH3CN solution for these complexes in an attempt to identify any distance or orientation dependency that may account for the differing rate constants observed. The calculated conformational distributions together with analysis by H-1 NMR for the [ZnL4a](2+) trans complex in the common trans-III N-based isomer gave a calculated Forster rate constant close to that observed experimentally. For the [ZnL4b](2+) cis complex, the experimentally determined rate constant may be attributed to a combination of trans-Ill and trans-I N-based isomeric forms of the complex in solution.

O papel do governo eletr??nico no fortalecimento da governan??a do setor p??blico

As novas Tecnologias da Informa????o e Comunica????o (TIC), entre as quais se destacam a internet, as redes de computadores, a transmiss??o via sat??lite e a telefonia m??vel, criaram condi????es para o surgimento de Sociedades do Conhecimento. Nesse contexto, o Estado, por interm??dio do governo eletr??nico, ?? o principal instrumento de que os cidad??os disp??em atualmente para enfrentar os desafios impostos pela globaliza????o, por meio de intera????es in??ditas da sociedade, empresas e governos. O objetivo deste trabalho foi estabelecer rela????es entre a governan??a do setor p??blico e o governo eletr??nico, partindo-se de um marco referencial te??rico das duas ??reas de estudo. Para tanto, foram delineados seus escopos e limites de atua????o, instituindo-se v??nculos, de acordo com a????es do Governo Eletr??nico brasileiro: certifica????o digital; Portal da Transpar??ncia; vota????o eletr??nica; preg??es eletr??nicos e Portal da Previd??ncia Social. Conclui-se que, apesar dos avan??os recentes observados pela an??lise de v??rias dimens??es da governan??a, baseados em iniciativas de governo eletr??nico aqui inventariadas, ainda h?? muito que fazer em dire????o ?? inclus??o social no Brasil, assim como em outros pa??ses. As TIC podem vir a ser um poderoso agente de inclus??o digital, apoiando a governan??a com a cria????o de espa??os virtuais para participa????o democr??tica e di??logo c??vico e expans??o da participa????o em tomada de decis??o coletiva, promovendo a igualdade e a cidadania.

Uso de tecnologias de informa????o e comunica????o na gest??o p??blica: exemplos no governo federal

A administra????o p??blica passou por diversas mudan??as nos ??ltimos 30 anos. Parte dessas altera????es tem origem nas oportunidades criadas pelas inova????es tecnol??gicas. O objetivo deste trabalho ?? apresentar como tem sido o uso de tecnologias da informa????o e comunica????o (TICs) nas inova????es promovidas na administra????o p??blica federal brasileira. Para tanto, tomamos como base a descri????o de cinco experi??ncias inovadoras em TIC premiadas nos concursos anuais Inova????o na Gest??o P??blica Federal, realizados pela Escola Nacional de Administra????o P??blica (ENAP): o Portal da Transpar??ncia da Controladoria-Geral da Uni??o (CGU); o Programa Nacional do Livro Did??tico; o uso dos computadores de m??o pelo Instituto Brasileiro de Geografia e Estat??stica (IBGE); a entrega da Declara????o do Imposto de Renda via internet; e a utiliza????o de urnas eletr??nicas nas elei????es brasileiras. A despeito da relev??ncia dos avan??os do governo eletr??nico brasileiro at?? aqui, medidas de aprimoramento da intera????o entre os diversos ??rg??os p??blicos e tamb??m das pol??ticas p??blicas de inclus??o digital ainda se fazem necess??rias.

Sample surveys via electronic mail: a comprehensive perspective

Although postal questionnaires, personal interviewing, and telephone interviewing are the main methods of survey-based research, there is an increasing use of e-mail as a data collection medium. However, little, if any, published Western research in general and that of Turkish in particular have investigated e-mail survey technique from pure survey research perspective. Attempting to develop a framework to assess e-mail as a data collection mean, the purpose of this study is to explore e-mail-based questionnaire technique from complementary angles. To this goal, sample representativeness, data quality, response rates, and advantages and disadvantages of e-mail surveying are discussed.

Electronic government policies in Brazil: context, ICT management and outcomes

The State Reform processes combined with the emergence and use of Information and Communication Technology (ICT) originated electronic government policies and initiatives in Brazil. This paper dwells on Brazilian e-government by investigating the institutional design it assumed in the state's public sphere, and how it contributed to outcomes related to e-gov possibilities. The analyses were carried out under an interpretativist perspective by making use of Institutional Theory. From the analyses of interviews with relevant actors in the public sphere, such as state secretaries and presidents of public ICT companies, conclusions point towards low institutionalization of e-gov policies. The institutional design of Brazilian e-gov limits the use of ICT to provide integrated public services, to amplify participation and transparency, and to improve public policies management.

Combining the rational and relational perspectives of electronic trading

Many organisations make extensive use of electronic linkages to facilitate their trading exchanges with partners such as suppliers, distributors and customers. This research explores how the use of inter-organisational systems (IOS) both affects, and is affected by, the relationships between trading partners. In doing this, it brings together two existing but distinct perspectives and literatures; the rational view informed by IOS research, and the behavioural or relationship perspective embodied in inter-organisational relationships (IOR) literature. The research was undertaken in the European paper industry by means of six dyadic case studies. The dyads studied covered both traditional electronic data interchange systems and newer e-marketplace environments. A framework was derived from existing literature that integrates the two perspectives of interest. The framework was used to analyse the case studies undertaken and enabled the inter-relationship between IOS use and IOR to be explained.

Learning business strategies for competitive electronic marketplaces

This paper presents a Multi-Agent Market simulator designed for developing new agent market strategies based on a complete understanding of buyer and seller behaviors, preference models and pricing algorithms, considering user risk preferences and game theory for scenario analysis. This tool studies negotiations based on different market mechanisms and, time and behavior dependent strategies. The results of the negotiations between agents are analyzed by data mining algorithms in order to extract rules that give agents feedback to improve their strategies. The system also includes agents that are capable of improving their performance with their own experience, by adapting to the market conditions, and capable of considering other agent reactions.

Agent-based simulation of electronic marketplaces with decision support

This paper presents a Multi-Agent Market simulator designed for analyzing agent market strategies based on a complete understanding of buyer and seller behaviors, preference models and pricing algorithms, considering user risk preferences and game theory for scenario analysis. The system includes agents that are capable of improving their performance with their own experience, by adapting to the market conditions, and capable of considering other agents reactions.