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Fractional central differences and derivatives are studied in this article. These are generalisations to real orders of the ordinary positive (even and odd) integer order differences and derivatives, and also coincide with the well known Riesz potentials. The coherence of these definitions is studied by applying the definitions to functions with Fourier transformable functions. Some properties of these derivatives are presented and particular cases studied.

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Some programs and research networks are dealing with topics associated to the automtive sector and they observe one of the most significative sectores of modern economies. Because of that is so interesting to forecast some possible changes in an horizon of 10 to 20 years. But this exercse must not be centred only on technical aspects of automobile construction, or on the design, or even on the mobility systems. How one can face these problems, and how it can be so decisivelly important, is what we will try to answer in this paper that resumes some of the debates on the foresight exercises in Germany (Futur) and on the automotive sector in Portugal (WorTiS).

The foresight and scenario building methods can be an interesting reference for social sciences, especially in terms of innovative methods for labour process analysis. A scenario – as a central concept for the prospective analysis – can be considered as a rich and detailed portrait of a plausible future world. It can be a useful tool for policy-makers to grasp problems clearly and comprehensively, and to better pinpoint challenges as well as opportunities in an overall framework. The features of the foresight methods are being used in some labour policy making experiences. Case studies developed in Portugal will be presented, and some conclusions will be drawn in order to organise a set of principles for foresight analysis applied to the European project WORKS on the work organisation re-structuring in the knowledge society, and on the work design methods for new management structures of virtual organisations.

Superoxide reductase (SOR) is a metalloprotein containing a non-heme iron centre, responsible for the scavenging of superoxide radicals in the cell. The crystal structure of Treponema pallidum (Tp) SOR was determined using soft X-rays and synchrotron radiation. Crystals of the oxidized form were obtained using poly(ethylene glycol) and MgCl2 and diffracted beyond 1.55 A resolution. The overall architecture is very similar to that of other known SORs but TpSOR contains an N-terminal domain in which the desulforedoxin-type Fe centre, found in other SORs, is absent. This domain conserves the beta-barrel topology with an overall arrangement very similar to that of other SOR proteins where the centre is present. The absence of the iron ion and its ligands, however, causes a decrease in the cohesion of the domain and some disorder is observed, particularly in the region where the metal would be harboured. The C-terminal domain exhibits the characteristic immunoglobulin-like fold and harbours the Fe(His)4(Cys) active site. The five ligands of the iron centre are well conserved despite some disorder observed for one of the four molecules in the asymmetric unit. The participation of a glutamate as the sixth ligand of some of the iron centres in Pyrococcus furiosus SOR was not observed in TpSOR. A possible explanation is that either X-ray photoreduction occurred or there was a mixture of redox states at the start of data collection. In agreement with earlier proposals, details in the TpSOR structure also suggest that Lys49 might be involved in attraction of superoxide to the active site.

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The foresight and scenario building methods can be an interesting reference for social sciences, especially in terms of innovative methods for labour process analysis. A scenario – as a central concept for the prospective analysis – can be considered as a rich and detailed portrait of a plausible future world. It can be a useful tool for policy-makers to grasp problems clearly and comprehensively, and to better pinpoint challenges as well as opportunities in an overall framework. The features of the foresight methods are being used in some labour policy making experiences. Case studies developed in Portugal will be presented, and some conclusions will be drawn in order to organise a set of principles for foresight analysis applied to the European project WORKS on the work organisation re-structuring in the knowledge society, and on the work design methods for new management structures of virtual organisations.

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A definition of the fractional Brownian motion based on the fractional differintegrator characteristics is proposed and studied. It is shown that the model enjoys the usually required properties. A discrete-time version based in the backward difference and in the bilinear transformation is considered. Some results are presented.

The macrocyclic phenanthrolinophane 2,9-[2,5,8-triaza-5-(N-anthracene-9-methylamino) ethyl]-[9]-1,10-henanthrolinophane(L) bearing a pendant arm containing a coordinating amine and an anthracene group forms stable complexes with Zn(II), Cd(II) and Hg(II) in solution. Stability constants of these complexes were determined in 0.10 mol dm(-3) NMe4Cl H2O-MeCN (1:1, v/v) solution at 298.1+/-0.1 K by means of potentiometric (pH metric) titration. The fluorescence emission properties of these complexes were studied in this solvent. For the Zn(II) complex, steady-state and time-resolved fluorescence studies were performed in ethanol solution and in the solid state. In solution, intramolecular pi-stacking interaction between phenanthroline and anthracene in the ground state and exciplex emission in the excited state were observed. From the temperature dependence of the photostationary ratio (I-Exc/I-M), the activation energy for the exciplex formation (E-a) and the binding energy of the exciplex (-DeltaH) were determined. The crystal structure of the [ZnLBr](ClO4).H2O compound was resolved, showing that in the solid state both intra- and inter-molecular pi-stacking interactions are present. Such interactions were also evidenced by UV-vis absorption and emission spectra in the solid state. The absorption spectrum of a thin film of the solid complex is red-shifted compared with the solution spectra, whereas its emission spectrum reveals the unique featureless exciplex band, blue shifted compared with the solution. In conjunction with X-ray data the solid-state data was interpreted as being due to a new exciplex where no pi-stacking (full overlap of the pi-electron cloud of the two chromophores-anthracene and phenanthroline) is observed. L is a fluorescent chemosensor able to signal Zn(II) in presence of Cd(II) and Hg(II), since the last two metal ions do not give rise either to the formation of pi-stacking complexes or to exciplex emission in solution.

Speciation studies in aqueous solution on the interaction Of Cu2+ and Zn2+ with a series of polyaminic ligands N-naphthalen-1-ylmethyl-N'-[2-[(naphthalen-1-ylmethyl)- amino]-ethyl)-ethane-l,2-diamine (LI), N-naphthalen-lylmethyl-iV-(2-{2-[(naphthalen-1-ylmethyl)-amino]-ethyl- amino]-ethyl)-ethane-l,2-diamine (L2) and N-naphthalen-1-ylmethyl-N'-[2-(2-{2-[(naphthalen-1-ylmethyl)-amino]- ethylamino)-ethylamino)-ethyl]-ethane-1,2-diamine (L3) containing two naphthylmethyl groups at their termini and N-1-(2-{2-[(naphthalen-1-ylmethyl)-amino]-ethyl-amino)-ethyl)-ethane-1,2-diamine (L4) containing just one naphthylmethyl group have been carried out at 298.1 K in 0.15 mol dm (-3) NaCl. In the case of the tetraamines L2 and L4, their coordination capabilities towards Cd2+, Ni2+, Co2+ and Pb2+ have also been considered. The stability constants follow the general Irving-Williams sequence. The steady-state fluorescence emission studies on the interaction with metal ions show that while Cu2+ produces a chelation enhancement of the quenching (CHEQ), the interaction with Zn2+ leads to a chelation enhancement of the fluorescence (CHEF). Finally, ligands L1, L2 and L3 have been successfully covalently attached to silica surfaces and some preliminary results of their emissive properties are given.