Digital Cities: Towards an integrated decision support methodology

This paper deals with the problem of the low ICT adoption rate by many cities or urban regions. The consequences of the poor ICT environment in these authorities may be summarized into (i) the cutback of local business competitiveness, (ii) the incapability of attracting new business investments, (iii) the poor service of citizens needs (living in the local area or abroad – a foreign country or another city, namely emigrants), (iv) the poor service of visitors that have or want to have transactions in the local area. The main shortcomings of local authorities refer to lack of capabilities and expertise, negligence of local needs and urban characteristics, absence of ICT adoption models to local needs, ignorance of development and exploitation models etc. These regions need support so as to select the most appropriate ICT best practices, integrated them into their strategic plans and implement them with success. This procedure is particularly complex, since many factors and restrictions have to be considered. The overall objective of this paper is to illustrate the Digital City concept and to propose an integrated methodology for Digital City development that will act in a supportive way for the regions or cities that have low rates in ICT penetration and try to adopt ICT best practices into their core functions and services.     

LC–UV determination of atrazine and its principal conversion products in soil after combined microwave-assisted and solid-phase extraction

A multiresidue method developed for the analysis of atrazine and its principal conversion products, deisopropylatrazine (DIA), deethylatrazine (DEA) and hydroxyatrazine (HA), in soil is presented. The method is based on the microwave-assisted extraction (MAE) of soil with aqueous methanol followed by solid-phase extraction (SPE) of the extracts and subsequent analysis by LC–UV with a diode array detector. MAE operational parameters (extraction solvent, extractant volume) were optimized with respect to extraction efficiency of the target compounds from soils with 2.5% organic matter (OM) content. Recoveries above 80% were obtained for all solutes. Soil OM content did not affect analyte recoveries. Recoveries from fresh and aged residues, the latter weathered under cold storage conditions, were not statistically different. Finally, MAE was found to be superior in terms of extraction efficiency, sample throughput, and solvent consumption to conventional flask-shaking extraction.     

Optimizing silicon-plasmonic waveguides for \chi ^{(3)} nonlinear applications

Hybrid silicon-plasmonic waveguides constitute an appealing platform for integrated photonic circuitry. They merge the technical maturity and prevalence of the SOI platform with the subwavelength confinement of plasmonic waveguides, essential for accessing enhanced nonlinear response at micron length-scales. Employing full-wave numerical simulations complemented with Schrödinger equation techniques, we propose nonlinear waveguide designs for Kerr-effect applications exhibiting minimized impairments due to free-carrier effects, thus raising the power-ceiling imposed on standard silicon waveguides.     

A multi-residue method for pesticide residue analysis in rice grains using matrix solid-phase dispersion extraction and high-performance liquid chromatography–diode array detection

Pesticides are widely used in rice cultivation, often resulting in detection of their residues in rice grains. So far, no analytical method has been available for the simultaneous determination of most rice pesticides in rice grains. This paper reports the development and validation of such a method for the determination of eight rice pesticides (penoxsulam tricyclazole, propanil, azoxystrobin, molinate, profoxydim, cyhalofop-butyl, deltamethrin) and 3,4-dichloroaniline, the main metabolite of propanil. Pesticide extraction and clean-up was performed by an optimized matrix solid-phase dispersion (MSPD) protocol on neutral alumina (5 g) using acetonitrile as the elution solvent. Samples were analyzed in a high-performance liquid chromatography–diode array detection (HPLC-DAD) system. Pesticide separation was achieved with a mobile phase of acetonitrile/water in a linear elution gradient from 30:70% (v/v) to 100:0% (v/v) in 14 min at a flow rate of 0.8 mL min^?1. Method validation was performed by means of linearity, intra-day accuracy, inter-day precision and sensitivity. Linear regression coefficients (R ²) were always above 0.9948. Limits of detection (LOD) and quantification (LOQ) varied from 0.002 to 0.200 mg kg^?1 and 0.006 to 0.600 mg kg^?1, respectively. Recoveries were investigated at three fortification levels and were found to be acceptable (74–127%) with relative standard deviations (RSD) below 12%. Application of the method for the analysis of five commercial rice grain samples showed that the pesticide levels were below the LOD. Overall, the method developed is suitable for the determination of residues of most rice pesticides in rice grains at levels below the established MRLs.     

Excited-state dynamics of carotenoids in light-harvesting complexes. 2. Dissecting pulse structures from optimal control experiments

Dispersed multipump-probe (PPP) spectroscopy was used to explore the role of saturation, annihilation, and structured pulses in recent coherent control experiments on the light-harvesting 2 complex from Rhodopseudomonas acidophila (Herek et al. Nature 2002, 417, 533). We discuss the complimentary aspects between the PPP technique and coherent control studies, in particular the ability to dissect complicated pulse structures and the utility in exploring incoherent mechanisms. With the aid of a simple multistate model involving only population dynamics, we illustrate how the optimized structured pulses may be explained in terms of an interplay between excited-state populations, saturation, and annihilation. Furthermore, we discuss the experimental conditions that are required for incoherent effects to contribute to control experimental signals, with particular emphasis on pulse intensities, and show that the optimization of a ratio of conservative signals (i.e., not modulated by external dynamics) is required to exclude saturation effects from coherent control studies.     

Divergence form operators in Reifenberg flat domains

We study the boundary regularity of solutions of elliptic operators in divergence form with C ^0,α coefficients or operators which are small perturbations of the Laplacian in non-smooth domains. We show that, as in the case of the Laplacian, there exists a close relationship between the regularity of the corresponding elliptic measure and the geometry of the domain.     

The charge-transfer character of the S0 --> S2 transition in the carotenoid peridinin is revealed by Stark spectroscopy

Peridinin, the carotenoid in the peridinin chlorophyll a protein (PCP), was studied by Stark (electroabsorption) spectroscopy to determine the change in electrostatic properties produced on excitation within the absorption band, in methyl tetrahydrofuran (MeTHF) versus ethylene glycol (EG), at 77 K. Strikingly, a large change in the permanent dipole moment (|Deltamu|) was found between the ground state, S(0) (1(1)A(g)(-)), and the Franck-Condon region of the S(2) (1(1)B(u)(+)) excited state, in both MeTHF (22 D) and EG (approximately 27 D), thus revealing the previously unknown charge transfer (CT) character of this pi-pi transition in peridinin. Such a large |Deltamu| produced on excitation, we suggest, facilitates the bending of the lactone moiety, toward which charge transfer occurs, and the subsequent formation of the previously identified intramolecular CT (ICT) state at lower energy. This unexpectedly large S(2) dipole moment, which has not been predicted even from high-level electronic structure calculations, is supported by calculating the shift of the peridinin absorption band as a function of solvent polarity, using the experimentally derived result. Overall, the photoinduced charge transfer uncovered here is expected to affect the excited-state reactivity of peridinin and, within the protein, be important for efficient energy transfer from the carotenoid S(2) and S(1)/ICT states to the chlorophylls in PCP.     

Induced Projective Modules Over Group von Neumann Algebras

Let G be a group and k a subring of the field of complex numbers. In this paper we study the additive map in reduced K-theory, which is associated with the inclusion of the group algebra kG into the group von Neumann algebra G, and obtain necessary and sufficient conditions for it to be identically zero (or zero modulo torsion). Our results complete the work of Eckmann [Comm. Math. Helvet. 71 (1996), 453–462; Arch. Math. 76 (2001), 241–249] and Schafer [K-theory 19 (2000), 211–217], while reducing to Swan’s theorem on induced representations [Ann. Math. 71 (1960), 552–578], in the case where the group G is finite. (Received: January 2005) Research supported by University of Athens grant Pythagoras 70/3/7298.     

Assembly of quantum dots on peptide nanostructures and their spectroscopic properties

We present a chemical process for the decoration of self-assembled two-dimensional peptide fibrils with two different sizes of CdSe@ZnS core–shell quantum dots (Qdots) capped with trioctylphosphine oxide molecules. The attachment of the semiconducting nanoparticles to the fibrils is directed via disulfide bond between the quantum dot and cysteine aminoacids that are deliberately impeded in the peptide structures. A significant red shift in the emission spectra of the quantum dots is observed and attributed to the synergistic interaction between adjacent nanoparticles arranged on peptide film templates extending over hundreds of nanometers.