SCIENTIFIC LANGUAGE RHETORIC: FROM THE THEORETICAL BASIS TO THE PRODUCTION OF DIDACTIC MATERIAL FOR UNDERGRADUATE CHEMISTRY TEACHING

This work is part of a study that focused on analyzing the contributions of didactic activities related to scientific language rhetoric characteristics aimed at developing students' abilities to identify such characteristics in chemistry scientific texts and critical reading of those texts. In this study, we present the theoretical basis adopted to determine the scientific discourse characteristics and for the production of the didactic material used in those activities. Latour, Coracini and Campanario studies on persuasive rhetorical strategies present in scientific articles aided the production of such material.

A theoretical model for estimating the margination constant of leukocytes

Abstract Background Blood leukocytes constitute two interchangeable sub-populations, the marginated and circulating pools. These two sub-compartments are found in normal conditions and are potentially affected by non-normal situations, either pathological or physiological. The dynamics between the compartments is governed by rate constants of margination (M) and return to circulation (R). Therefore, estimates of M and R may prove of great importance to a deeper understanding of many conditions. However, there has been a lack of formalism in order to approach such estimates. The few attempts to furnish an estimation of M and R neither rely on clearly stated models that precisely say which rate constant is under estimation nor recognize which factors may influence the estimation. Results The returning of the blood pools to a steady-state value after a perturbation (e.g., epinephrine injection) was modeled by a second-order differential equation. This equation has two eigenvalues, related to a fast- and to a slow-component of the dynamics. The model makes it possible to identify that these components are partitioned into three constants: R, M and SB; where SB is a time-invariant exit to tissues rate constant. Three examples of the computations are worked and a tentative estimation of R for mouse monocytes is presented. Conclusions This study establishes a firm theoretical basis for the estimation of the rate constants of the dynamics between the blood sub-compartments of white cells. It shows, for the first time, that the estimation must also take into account the exit to tissues rate constant, SB.

Déficit abrangência nas narrativas da contemporaneidade

O artigo analisa as narrativas da contemporaneidade, na vertente da reportagem, e cruza as práticas jornalísticas com o discurso científico da complexidade. Do intercâmbio inter e transdisciplinar, apresenta os desafios epistemológicos vivenciados nas mediações sociais da comunicação. Dessa forma, o presente texto desliza constantemente entre as narrativas das mídias brasileiras contemporâneas sobre temas emergentes e os suportes teóricos que desenvolveu em sua obra. Apontando as dinâmicas empíricas e a crise dos paradigmas teóricos, o artigo apresenta, ainda, um diagnóstico do deficit de complexidade nas práticas interpretativas da experiência coletiva.

CARBON MARKET AND INSTITUTIONS: OPPORTUNITIES IN THE SEARCH OF A NEW MODEL FOR DEVELOPMENT

Seeking alternatives for the economic system to face the several crises it has gone through lately (electrical power, cultural, financing and technological) brought about a new market involving the Kyoto Protocol signatory countries: the carbon market. The present article aims at assessing the carbon market institutional issue in Brazil by identifying the risks and opportunities inherent to the institutional agent characteristics and to that market rules. The research methodology was bibliographic and based on the analysis of the Securities and Exchange Commission of Brazil (Comissao de Valores Mobiliarios and Bolsa Mercantil de Valores) contents. Its theoretical basis rests on concepts of the institution and the new institutional economy. The results show that in spite of the risks and institutional problems it involves, the carbon market is promising due to the opportunities create by new technologies and energies developed to achieve and sustain the capitalist system new cycle, addressed to produce a clean development.

A retórica da linguagem científica: das bases teóricas à elaboração de material didático para o ensino superior de Química

This work is part of a study that focused on analyzing the contributions of didactic activities related to scientific language rhetoric characteristics aimed at developing students' abilities to identify such characteristics in chemistry scientific texts and critical reading of those texts. In this study, we present the theoretical basis adopted to determine the scientific discourse characteristics and for the production of the didactic material used in those activities. Latour, Coracini and Campanario studies on persuasive rhetorical strategies present in scientific articles aided the production of such material.

Studying the genetic basis of drought tolerance in sorghum by managed stress trials and adjustments for phenological and plant height differences

Managed environments in the form of well watered and water stressed trials were performed to study the genetic basis of grain yield and stay green in sorghum with the objective of validating previously detected QTL. As variations in phenology and plant height may influence QTL detection for the target traits, QTL for flowering time and plant height were introduced as cofactors in QTL analyses for yield and stay green. All but one of the flowering time QTL were detected near yield and stay green QTL. Similar co-localization was observed for two plant height QTL. QTL analysis for yield, using flowering time/plant height cofactors, led to yield QTL on chromosomes 2, 3, 6, 8 and 10. For stay green, QTL on chromosomes 3, 4, 8 and 10 were not related to differences in flowering time/plant height. The physical positions for markers in QTL regions projected on the sorghum genome suggest that the previously detected plant height QTL, Sb-HT9-1, and Dw2, in addition to the maturity gene, Ma5, had a major confounding impact on the expression of yield and stay green QTL. Co-localization between an apparently novel stay green QTL and a yield QTL on chromosome 3 suggests there is potential for indirect selection based on stay green to improve drought tolerance in sorghum. Our QTL study was carried out with a moderately sized population and spanned a limited geographic range, but still the results strongly emphasize the necessity of corrections for phenology in QTL mapping for drought tolerance traits in sorghum.

The search for a potentially new molecular species, SiAs: A theoretical contribution

Electronic states of a new molecular species, SiAs, correlating with the three lowest dissociation channels are characterized at a high-level of theory using the CASSCF/MRCI approach along with quintuple-xi quality basis sets. This characterization includes potential energy curves, vibrational energy levels, spectroscopic parameters, dipole and transition dipole moment functions, transition probabilities, and radiative lifetimes. For the ground state (X-2 Pi), an assessment of spin-orbit effects and the interaction with the close-lying A(2)Sigma(+) state is also reported. Similarities and differences with other isovalent species such as SiP and CAs are also discussed.

A theoretical contribution characterizing a potentially new molecular species: MgAs

A new molecular species, MgAs, is investigated theoretically for the first time at the CASSCF/MRCI level using quintuple-zeta quality basis sets. Potential energy curves for the lowest-lying electronic states are presented as well as the associated spectroscopic constants. Dipole and transition moment functions for selected states complement this characterization. Estimates of transition probabilities and radiative life-times for the most important transitions are also reported. The effect of spin-orbit interactions is clearly reflected on the potential energy curves. Comparisons with BeAs, BeN, and BeP are made where pertinent. (C) 2011 Elsevier B.V. All rights reserved.

Theoretical study of the XP3 (X = Al, B, Ga) clusters

The lowest singlet and triplet states of AlP3, GaP3 and BP3 molecules with C-s, C-2v and C-3v symmetries were characterized using the B3LYP functional and the aug-cc-pVTZ and aug-cc-pVQZ correlated consistent basis sets. Geometrical parameters and vibrational frequencies were calculated and compared to existent experimental and theoretical data. Relative energies were obtained with single point CCSD(T) calculations using the aug-cc-pVTZ, aug-cc-pVQZ and aug-cc-pV5Z basis sets, and then extrapolating to the complete basis set (CBS) limit. (C) 2011 Elsevier B.V. All rights reserved.

Theoretical study of the absorption and nonradiative deactivation of 1-nitronaphthalene in the low-lying singlet and triplet excited states including methanol and ethanol solvent effects

The photophysics of the 1-nitronaphthalene molecular system, after the absorption transition to the first singlet excited state, is theoretically studied for investigating the ultrafast multiplicity change to the triplet manifold. The consecutive transient absorption spectra experimentally observed in this molecular system are also studied. To identify the electronic states involved in the nonradiative decay, the minimum energy path of the first singlet excited state is obtained using the complete active space self-consistent field//configurational second-order perturbation approach. A near degeneracy region was found between the first singlet and the second triplet excited states with large spin-orbit coupling between them. The intersystem crossing rate was also evaluated. To support the proposed deactivation model the transient absorption spectra observed in the experiments were also considered. For this, computer simulations using sequential quantum mechanic-molecular mechanic methodology was used to consider the solvent effect in the ground and excited states for proper comparison with the experimental results. The absorption transitions from the second triplet excited state in the relaxed geometry permit to describe the transient absorption band experimentally observed around 200 fs after the absorption transition. This indicates that the T-2 electronic state is populated through the intersystem crossing presented here. The two transient absorption bands experimentally observed between 2 and 45 ps after the absorption transition are described here as the T-1 -> T-3 and T-1 -> T-5 transitions, supporting that the intermediate triplet state (T-2) decays by internal conversion to T-1. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4738757]

The radical SeCl: A theoretical contribution to the characterization of its low-lying electronic states

All doublet and quartet electronic states correlating with the first dissociation channel of SeCl and some Rydberg states are investigated theoretically at the CASSCF/MRCI level of theory using extended basis sets, including the contribution of spin-orbit effects. The similarity of the potential energy curves with those of SeF suggests that spectroscopic constants for the ground (X (2)Pi) and the first excited quartet (a(4)Sigma) of SeCl could also be determined via an emission resulting from the reaction of selenium with atomic chlorine. The coupling constant of the ground state at R-e is estimated as -1610 cm (1). The potential energy curves calculated and the derived spectroscopic constants do not support the interpretation and assignment of the scarce transitions recorded experimentally as due to (2)Pi-(2)Pi emissions. That the few observed lines might arise from transitions from the state b(4)Sigma(-)(1/2) to a very high vibrational level of the state a(4)Sigma(-)(1/2) is an open possibility, however, the number of vibrational states and the calculated Delta G(1/2) differ significantly from the reported ones. (C) 2012 Elsevier B. V. All rights reserved.