Optically Active Spherical Polyelectrolyte Brushes with a Nanocrystalline Magnetic Core

The unique properties of magnetic nanocrystals have triggered intensive research towards their effective functionalization and application in many technological fields. Although synthesis of magnetic colloids is being thoroughly studied, there is limited knowledge on the synthesis, characterization, and properties of magnetic polyelectrolyte spherical brushes. In the present work, the preparation of such hybrids and the subsequent formation of stable aqueous colloids are described. The core of the spherical brush consists of a magnetic γ‐Fe₂O₃ nanocrystallite (faceted but mostly spherical‐like) with a mean diameter of 17 nm. The bioadhesive polyelectrolyte poly(sodium 4‐styrene sulfonate), forming the surrounding brush layer, was proven to be an effective covalently modifying macromolecule for the iron oxide surface, as Fourier transform IR spectroscopy revealed. Several observations on colloidal aspects are discussed and are successfully explained by models and experiments describing polyelectrolyte brushes with a soft polymeric core. Finally, the hybrids exhibit their multifunctional character and their technological importance by combining in a single and soluble product with magnetic and nonlinear optical properties.     

Delivering a lifelong integrated electronic health record based on a service oriented architecture.

Efficient access to a citizen's Integrated Electronic Health Record (I-EHR) is considered to be the cornerstone for the support of continuity of care, the reduction of avoidable mistakes, and the provision of tools and methods to support evidence-based medicine. For the past several years, a number of applications and services (including a lifelong I-EHR) have been installed, and enterprise and regional infrastructure has been developed, in HYGEIAnet, the Regional Health Information Network (RHIN) of the island of Crete, Greece. Through this paper, the technological effort toward the delivery of a lifelong I-EHR by means of World Wide Web Consortium (W3C) technologies, on top of a service-oriented architecture that reuses already existing middleware components is presented and critical issues are discussed. Certain design and development decisions are exposed and explained, laying this way the ground for coordinated, dynamic navigation to personalized healthcare delivery.     

Environmental cost-effectiveness of bio diesel production in Greece: Current policies and alternative scenarios

Following European Directive 2003/30/EC, the Greek Government adapted legislation that introduces and regulates the bio diesel market. The implemented quota scheme allocates the country's annual, predetermined, tax exempt production of bio diesel to industries based on their ability to meet several criteria. A number of bio diesel supply chain stakeholders have criticized this policy for being efficiency-robbing and vague. This paper uses 2007 data from energy crop farms and three bio diesel-producing companies in order to assess these criticisms. We study the economic and environmental aspects of the currently adopted policy and compare them to three alternative scenarios. We conclude that such criticisms have a merit and that policy makers need to reconsider their alternative options regarding the promotion of bio diesel in transport. Permission of sales directly to local consumers and promotion of forward integration by farmers are efficiency enhancing and environment-friendly means of promoting the use of bio diesel in transport.     

The influence of the type of loading and temperature on the modulus of elasticity of cement-bound mixes of milled bituminous concrete and crushed aggregates

Combinations in various proportions of milled bituminous concrete and crushed limestone aggregates were mixed in the laboratory with 5% by mass cement and 5% by mass water to simulate some of the materials that can be obtained when mix-in-place recycling with cement is used. The influence of the temperature and of the type of loading (different rates of stress application of ramp loading and different frequencies of sinusoidal loading) on the modulus of elasticity is examined. It is concluded that as the milled bituminous concrete content in the mix is increased, both the temperature and the rate of stress application increasingly influence the results, and this should be taken into consideration when specifying or designing pavements incorporating cement-bound materials of this type.     

Efficiency Limits for Slip-on Type Buckle Arrestors for Offshore Pipelines

Slip-on buckle arrestors for offshore pipelines offer important advantages over other arrestor designs as they do not require welding. An additional advantage offered by the related concept of the two-part clamp-on arrestor is that it can be installed onto a continuous pipe. It has long been known that such devices often cannot reach higher arresting efficiencies. As a result, the use of slip-on arrestors in deepwater applications has been limited. The somewhat deficient performance is due to the fact that a propagating buckle can penetrate such devices via a folded-up U mode at pressures that are lower than the collapse pressure of the pipe. This can take place even for very rigid rings. A methodology for generating bounds on the maximum arresting efficiency that can be expected from slip-on arrestors is developed. An upper bound of their efficiency is related to the pressure at which a propagating buckle starts to penetrate a long and stiff circumferential confinement. A lower bound is established by relating the crossover pressure to the lowest pressure at which the buckle will propagate through the confinement. The parametric dependence of both of these pressures was established experimentally. The method developed yields the range of pipe D/t’s where degradation in arresting efficiency can be expected and predicts its extent. The arresting efficiency degradation was shown to depend on the yield stress of the pipe. Pipe of higher yield stress exhibits smaller degradation in arresting efficiency.     

Scattering from two eccentric spheroids: Theory and numerical investigation

In this paper, the direct acoustic scattering problem of a point source field by a penetrable spheroidal scatterer hosting an impenetrable spheroidal body of arbitrary position, size and orientation, is considered. The application background corresponds to the near field measurement of the acoustic field, scattered by a soft-tissue organ including a hard inhomogeneity. The methodology incorporates two independent techniques which are modified appropriately to fit together and are combined for the first time: first, the Vekua method, which is based on the well known Vekua transformation, providing with fully analytic solutions of Helmholtz equation and second, the method of auxiliary sources in order to represent the net wave contribution of the inhomogeneity. The satisfaction of transmission and boundary conditions is accomplished via the collocation method while the wave character of the fields and the outwards propagating property of the exterior wave are implicitly guaranteed in exact form through the analytic nature of the method. Special effort has been devoted to the self-evaluation of the method by constructing and calculating an indicative error function representing the failure of satisfaction of the boundary conditions on a rich grid over the interfaces, much larger than the set of collocation points, where the error is by construction negligible. This numerical approach leads to very reliable results. The determination of the near scattered field as well as of the far-field pattern are the final outcomes of the present work, providing a thorough solution of the direct scattering problem and giving insight to the corresponding inverse problem.     

Timescale Analysis with an Entropy-Based Shift-Invariant Discrete Wavelet Transform

This paper presents an invariant discrete wavelet transform that enables point-to-point (aligned) comparison among all scales, contains no phase shifts, relaxes the strict assumption of a dyadic-length time series, deals effectively with boundary effects and is asymptotically efficient. It also introduces a new entropy-based methodology for the determination of the optimal level of the multiresolution decomposition, as opposed to subjective or ad-hoc approaches used hitherto. As an empirical application, the paper relies on wavelet analysis to reveal the complex dynamics across different timescales for one of the most widely traded foreign exchange rates, namely the Great Britain Pound. The examined period covers the global financial crisis and the Eurozone debt crisis. The timescale analysis attempts to explore the micro-dynamics of across-scale heterogeneity in the second moment (volatility) on the basis of market agent behavior with different trading preferences and information flows across scales. New stylized properties emerge in the volatility structure and the implications for the flow of information across scales are inferred.     

A novel Bayesian strategy for the identification of spatially varying material properties and model validation: an application to static elastography

The present paper proposes a novel Bayesian, a computational strategy in the context of model‐based inverse problems in elastostatics. On one hand, we attempt to provide probabilistic estimates of the material properties and their spatial variability that account for the various sources of uncertainty. On the other hand, we attempt to address the question of model fidelity in relation to the experimental reality and particularly in the context of the material constitutive law adopted. This is especially important in biomedical settings when the inferred material properties will be used to make decisions/diagnoses. We propose an expanded parametrization that enables the quantification of model discrepancies in addition to the constitutive parameters. We propose scalable computational strategies for carrying out inference and learning tasks and demonstrate their effectiveness in numerical examples with noiseless and noisy synthetic data. Copyright © 2012 John Wiley & Sons, Ltd.     

Third‐Order Nonlinear Optical Response of Gold‐Island Films

Films of gold nanoscaled islands with thicknesses ranging between 0.5 and 15 nm were prepared by thermal evaporation onto untreated and aminosilane‐pretreated glass substrates. Post‐deposition annealing was found to modify the morphological characteristics of the islands (e.g., average island area and height, inter‐island distance, etc.), resulting in changes of the localized surface plasmon resonance (SPR) characteristics and, therefore, modifying the nonlinear optical (NLO) response of the films. The NLO response of both unannealed and annealed (20 h at 200 °C) films was studied by means of the optical Kerr effect (OKE), using 35 ps, 532 nm laser excitation, while measurements performed by means of the Z‐scan technique allowed for the determination of both the nonlinear refraction and absorption characteristics of the films. The results are discussed and compared with other reports.     

A novel experimental setup for gas microflows

A new experimental setup for flow rate measurement of gases through microsystems is presented. Its principle is based on two complementary techniques, called droplet tracking method and constant-volume method. Experimental data on helium and argon isothermal flows through rectangular microchannels are presented and compared with computational results based on a continuum model with second-order boundary conditions and on the linearized kinetic BGK equation. A very good agreement is found between theory and experiment for both gases, assuming purely diffuse accommodation at the walls. Also, some experimental data for a binary mixture of monatomic gases are presented and compared with kinetic theory based on the McCormack model.