Effect of diffusion-sensitizing gradient timings on the exponential,biexponential and diffusional kurtosis model parameters: in-vivo measurements in the rat thalamus

Object  

To investigate whether spacing (Δ) and duration (δ) of the diffusion-sensitizing gradient pulses differentially affect exponential (D′), biexponential (D _slow, D _fast and f _slow) and diffusional kurtosis (D and K) model parameters.     

Tailored One-Way and Two-Way Shape Memory Capabilities of Poly(ε-Caprolactone)-Based Systems for Biomedical Applications

This paper investigates the shape memory capabilities of semicrystalline networks, focusing the attention on poly(ε-caprolactone) (PCL) systems, a class of materials that allows to satisfy important requirements for their applications as biomedical devices, such as the good biocompatibility, the fast recovery of large “temporary” shape configurations, and the easy tailoring of the transformation temperatures. The materials were prepared with various crosslink densities and crosslinking methodologies; in particular, beside a thermal crosslinking based on reactive methacrylic end groups, a novel type of covalently crosslinked semicrystalline systems was prepared by a sol-gel approach from alkoxysilane-terminated PCL precursors, so as to avoid potentially toxic additives typically used for free-radical thermal curing. The materials were subjected to biological tests, to study their ability in sustaining cell adhesion and proliferation, and to thermal characterizations, to evaluate the possibility to tailor their melting and crystallization temperatures. The one-way shape memory (i.e., the possibility to set the material in a given configuration and to recover its pristine shape) and the two-way shape memory response (i.e., the triggered change between two distinguished shapes on the application of an on-off stimulus) were studied by applying optimized thermo-mechanical cyclic histories. The ability to fix the applied shape and to recover the original one on the application of heating (i.e., the one-way effect) was evaluated on tensile bars; further, to investigate a potential application as self-expandable stents, isothermal shape memory experiments were carried out also on tubular specimens, previously folded in a temporary compact configuration. The two-way response was studied through the application of a constant load and of a heating/cooling cycle from above melting to below the crystallization temperature, leading to a reversible elongation/contraction effect, involving maximum strain changes up to about 80%, whose extent may be controlled through the crosslink density.     

Adapting Creative Problem Solving to an Organizational Context: A Study of its Effectiveness with a Student Population

Owing to company time restrictions and concentration on project development, we began to reduce the duration of creative problem solving (CPS) sessions, and to give more emphasis to the action planning stage. Several changes in our CPS protocol, as well as in its duration, begged the question as to whether these changes were jeopardizing efficacy. To examine this question, six groups of ten university students, working under two different CPS protocols (a five‐step method and a four‐step method), and three control groups (using no CPS method), were given the same objective and similar conditions. This exploratory experiment compared group performance by change in team commitment, divergent thinking preferences, productivity and the participants' evaluation of the different methods. Results show that the CPS methods were both effective in changing participants' perspectives regarding divergent thinking and team commitment. In the control groups, however, there were no changes as a consequence of the sessions. Results also suggest that the same problem‐solving effectiveness can be attained in a shorter time than that traditionally used, and without prior training in CPS. These findings open the door to developing new problem‐solving techniques and team work processes, and to more efficient organizational creativity and innovation methodologies.     

Investigation of compatibility of a dicyanate ester monomer and polysulfone by size‐exclusion chromatography and viscometry

The influence of solvent on the compatibility behaviour of Arocy B10, a cyanate ester monomer, and polysulfone (PSF) was investigated by means of dilute solution viscometry and of the preferential solvation parameter at 25 °C. The ternary systems under study are: tetrahydrofuran/Arocy B10/polysulfone (PSF), N,N‐dimethylformamide/Arocy B10/PSF and dichloromethane/Arocy B10/PSF. Values of the specific viscosity of PSF in a ‘binary solvent’ formed by Arocy B10 + solvent have been used to determine the compatibility of the polymer blend Arocy B10/PSF. An interaction parameter Δb that depends on concentration has been determined. The preferential solvation parameter was measured by size‐exclusion chromatography at different monomer‐to‐polymer ratios. PSF was found to be preferentially solvated by the monomer. Both techniques agree quantitatively in every system indicating maximum compatibility at the same Arocy B10 concentration. However, they differ when comparing the two parameters among the three systems. Copyright © 2003 Society of Chemical Industry     

Embedding renewable cryptographic keys into noisy data

A fuzzy extractor is a powerful but theoretical tool that can be used to extract uniform strings from (discrete) noisy sources. However, when using a fuzzy extractor in practice, extra features are needed, such as the renewability of the extracted strings and the ability to use the fuzzy extractor directly on continuous input data instead of discrete data. Our contribution is threefold. Firstly, we propose a fuzzy embedder as a generalization of the fuzzy extractor. A fuzzy embedder naturally supports renewability, as it allows a string to be embedded instead of extracted. It also supports direct analysis of quantization effects, as it makes no limiting assumptions about the nature of the input source. Secondly, we give a general construction for fuzzy embedders based on the technique of quantization index modulation (QIM). We show that the performance measures of a QIM, as proposed by the watermarking community, translate directly to the security properties of the corresponding fuzzy embedder. Finally, we show that from the perspective of the length of the embedded string, quantization in two dimensions is optimal. We present two practical constructions for a fuzzy embedder in two-dimensional space. The first construction is optimal from reliability perspective, and the second construction is optimal in the length of the embedded string.     

Environmental analysis of the logistics of agricultural products from roof top greenhouses in Mediterranean urban areas

BACKGROUND: As urban populations increase so does the amount of food transported to cities worldwide, and innovative agro‐urban systems are being developed to integrate agricultural production into buildings; for example, by using roof top greenhouses (RTGs). This paper aims to quantify and compare, through a life cycle assessment, the environmental impact of the current linear supply system with a RTG system by using a case study for the production of tomatoes. RESULTS: The main results indicate that a change from the current linear system to the RTG system could result in a reduction, per kilogram of tomatoes (the functional unit), in the range of 44.4–75.5% for the different impact categories analysed, and savings of up to 73.5% in energy requirements. These savings are associated with re‐utilisation of packaging systems (55.4–85.2%), minimisation of transport requirements (7.6–15.6%) and reduction of the loss of product during transportation and retail stages (7.3–37%). CONCLUSIONS: The RTG may become a strategic factor in the design of low‐carbon cities in Mediterranean areas. Short‐term implementation in the city of Barcelona could result in savings of 66.1 tonnes of CO₂ eq. ha^?1 when considering the global warming potential, and of 71.03 t ha^?1 when considering that the transformation from woodland to agricultural land is avoided. Copyright © 2012 Society of Chemical Industry     

Fatty acid composition of bacteria associated with the toxic dinoflagellate Ostreopsis lenticularis and with caribbean Palythoa species

The fatty acid composition of a Pseudomonas sp. (Alteromonas) and its host, the dinoflagellate Ostreopsis lenticularis, vectors in ciguatera fish poisoning, has been studied. The major fatty acids in O. lenticularis were 16∶0, 20∶5n-3, and 22∶6n-3, but 18∶2n-6, 18∶3n-3, and 18∶n-3 were also identified. In contrast to other dinoflagellates, 18∶5n-3 was not detected in O. lenticularis. Even-chain fatty acids such as 9–16∶1, 11–18∶1, and 13–20∶1 predominated in the Pseudomonas sp. from O. lenticularis, but 16–20% of (E)-11-methyl-12-octadecenoic acid was also identified. The chirality of the latter was confirmed by total synthesis (28% overall yield) starting from oxacyclotridecan-2-one. The fatty acid compositions of two other Pseudomonas species, from the palytoxin-producing zoanthids Palythoa mamillosa and P. caribdea, were also studied and were similar to that of the Pseudomonas sp. from O. lenticularis. The possibility of using some of these fatty acids as chemotaxonomic lipids in identifying marine animals that consume toxic dinoflagellates or zoanthids is discussed.