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61.
In this paper we present and evaluate ContentPlace, a data dissemination system for opportunistic networks, i.e., mobile networks in which stable simultaneous multi-hop paths between communication endpoints cannot be provided. We consider a scenario in which users both produce and consume data objects. ContentPlace takes care of moving and replicating data objects in the network such that interested users receive them despite possible long disconnections, partitions, etc. Thanks to ContentPlace, data producers and consumers are completely decoupled, and might be never connected to the network at the same point in time. The key feature of ContentPlace is learning and exploiting information about the social behaviour of the users to drive the data dissemination process. This allows ContentPlace to be more efficient both in terms of data delivery and in terms of resource usage with respect to reference alternative solutions. The performance of ContentPlace is thoroughly investigated both through simulation and analytical models. 相似文献
62.
Chiara Vitale-Brovarone Francesco Baino Oana Bretcanu Enrica Verné 《Journal of materials science. Materials in medicine》2009,20(11):2197-2205
Glass–ceramic scaffolds mimicking the structure of cancellous bone were produced via sponge replication technique by using
a polyurethane foam as template and glass powder below 30 μm as inorganic phase. Specifically, a SiO2-based glass of complex composition and its corresponding P2O5-based “specular” glass were used as materials for scaffolding. The polymeric sponge was thermally removed and the glass powders
were sintered to obtain a replica of the template structure. The scaffolds were investigated and compared from a structural,
morphological and mechanical viewpoint by assessing their crystalline phases, volumetric shrinkage, pores content and interconnection,
mechanical strength. In addition, the scaffolds were soaked in acellular simulated body fluid to investigate their in vitro
behaviour. The produced scaffolds have a great potential for bone reconstructive surgery because their features, such as shape,
strength, bioactivity and bioresorption, can be easily tailored according to the end use. 相似文献
63.
Alessandro Abbotto Erika Herrera Calderon Norberto Manfredi Claudio Maria Mari Chiara Marinzi Riccardo Ruffo 《Synthetic Metals》2011,161(9-10):763-769
Vinylene-linked donor–acceptor–donor semiconducting polymers have been prepared by electropolymerization of the new monomers 2,6-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine and 2,5-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine. The monomers, consisting of two pyrrole donor units and a central pyridine acceptor ring spaced by vinylene links, differ by the substitution pattern around the central pyridine core (2,6 vs. 2,5-substitution). The electropolymerization process is more efficient on the 2,5-derivative. The new polymers show reversible electrochemistry dominated by a strong charge trapping effect. Poly(2,5-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine) energy levels closely match those of design rules for optimized polymers in combination with fullerene derivatives in bulk heterojunction solar cells. 相似文献
64.
Chiara Uboldi Daniele Bonacchi Giada Lorenzi M Iris Hermanns Christine Pohl Giovanni Baldi Ronald E Unger C James Kirkpatrick 《Particle and fibre toxicology》2009,6(1):18-12
Background
During the last years engineered nanoparticles (NPs) have been extensively used in different technologies and consequently many questions have arisen about the risk and the impact on human health following exposure to nanoparticles. Nevertheless, at present knowledge about the cytotoxicity induced by NPs is still largely incomplete. In this context, we have investigated the cytotoxicity induced by gold nanoparticles (AuNPs), which differed in size and purification grade (presence or absence of sodium citrate residues on the particle surface) in vitro, in the human alveolar type-II (ATII)-like cell lines A549 and NCIH441. 相似文献65.
66.
[Correction Notice: An erratum for this article was reported in Vol 3(1) of Psychological Trauma: Theory, Research, Practice, and Policy (see record 2010-26899-001). There were citation errors in the last sentence of the first column of text on page 9, and a reference was omitted from the reference list. The sentence should have read: “This result is consistent with other work that has found support for the anxious and dissociative reaction associated with trauma among Latinos and how it may relate to “ataque de nervios” (Hinton, Chong, Pollack, Barlow, & McNally, 2008; Lewis-Fernandez et al., 2002; Schechter et al., 2000; Tolin, Robinson, Gaztambide, Horowitz, & Blank, 2007).] [Correction Notice: An erratum for this article was reported in of Psychological Trauma: Theory, Research, Practice, and Policy (see record 2010-26899-001). In the original article there were citation errors in the last sentence of the first column of text on page 9, and a reference was omitted from the reference list. The sentence should have read: “This result is consistent with other work that has found support for the anxious and dissociative reaction associated with trauma among Latinos and how it may relate to “ataque de nervios” (Hinton, Chong, Pollack, Barlow, & McNally, 2008; Lewis-Fernandez et al., 2002; Schechter et al., 2000; Tolin, Robinson, Gaztambide, Horowitz, & Blank, 2007).] Research on the victimization of Latino women and the subsequent psychological impact has been limited by focusing on individual forms of victimization, primarily partner violence or sexual assault. Another deficiency includes mainly using convenience and/or geographically restricted samples, which impacts the generalizability of the results. To overcome these research limitations, the Sexual Assault Among Latinas (SALAS) study aimed to evaluate the broader scope of victimization among Latino women. The study surveyed a national sample of 2,000 Latino women using random digit dial methodology. Women were asked about various forms of victimization in childhood and adulthood including physical assaults, sexual assaults, stalking, threats, and witnessed violence, as well as psychological symptomatology including depression, anxiety, anger, and dissociation. This analysis found that victimized women were more likely to experience some form of polyvictimization and/or revictimization throughout their lives, with only 36% of victimized women experiencing one form of victimization in childhood or adulthood alone. Furthermore, multiple victimization experiences significantly increased the proportion of women who experienced psychological distress symptoms in the clinical range. For almost all evaluated symptoms, the multiple forms of victimization or varying victimization patterns significantly predicted clinical levels of psychological distress over any specific form or single incident of victimization. The results suggest that victimized Latino women experience multiple forms of victimization and that the evaluation of a broader spectrum of victimization better accounts for pathological symptomatology. Clinical implications for Latino women and future research directions are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
67.
In this work, a preliminary numerical model of the behavior of retro-reflective materials used as envelope coatings on street canyon buildings fa?ades has been tested. Retro-reflective materials have a surface finish that allows to reflect the solar radiation back in the same direction of the incident radiation. In the last years this kind of materials has been studied as buildings envelope coating for their potentials in the reduction of the UHI effect. As a matter of fact, the angular dependence of their optical–radiative response would help to mitigate the phenomenon of radiative entrapment due to the urban fabric environment. For this reason, an urban canyon was selected as the most common urban architecture to perform the analysis. A virtual retroreflective material has been simulated considering its response as almost diffusive but in the same direction of the incident radiation. The assessment of the energy advantages of the adoption of a virtual retro-reflective material as envelope coating is investigated by means of a numerical model developed in MATLAB and based on the Gebhart factors theory. The final purpose of the numerical model is the evaluation of the surfaces solar loads by a comparison between perfectly diffusive materials and RR materials used as fa?ades coating. 相似文献
68.
This study describes a hierarchical ranking model to help the selection of CRM (customer relationship management) packages based on their functional and technical quality. The model is tested empirically by applying the hierarchical analytical process (AHP) to a sample of 42 CRM packages. Results indicate how functionally similar packages can differ substantially in their technical quality and, thus, in their ability to be integrated within a companys information system. The hierarchical model is verified to be dependable, since the quality-based ranking of packages is found to have a low rank-reversal probability as a consequence of managers uncertainty in weighing the relevance of different quality variables. From a practical standpoint, these results confirm that CRM packages differentiate in measurable quality variables, which can be used by practitioners as a framework to gather and evaluate software-selection information during feasibility analyses. 相似文献
69.
A new method for decoding two-dimensional (2D) multicomponent separations based on the use of the 2D Autocovariance function (2D-ACVF) has been developed. Theoretical models of single component (SC) spot distributions in 2D separations, both random and structured, are developed as the basis for a nonlinear estimation of both sample and separation system parameters from experimental 2D separations. The number of SCs, the average spot size, the spot capacity, and the saturation factor can be evaluated in the case of random SC spot patterns. The procedure was validated by extensive numerical simulation under conditions close to those usually found in GC x GC or 2D-polyacrylamid gel electrophoresis of proteins. The worse precision degree was no greater than 10% in the case of maximum spot density. This imprecision was fully accounted for, and it seems acceptable owing to the intrinsic statistical character of the estimation method. Structured multicomponent 2D separations, where SCs are linked by linear relationships, give rise to specific structured patterns in 2D-ACVF plots from which the parameters (phase and frequency) of the structured SC sequences can be evaluated: the study of 2D-ACVF makes it possible to decode multicomponent 2D separation, that is, to determine the number, relative abundance, and structural similarities of the single components. Pertinent expressions of the theoretical 2D-ACVF were derived for simple cases, and a procedure for decoding cases of structured 2D separations was developed and applied. It was shown that 2D separations containing both random and structured patterns of SC spots give rise to 2D-EACVF, which is the superimposition of the two component parts. This feature allows one, in principle, to decode the two components. The relevance of these results for Giddings sample dimensionality and separation dimensionality and their effective experimental evaluation is discussed. 相似文献
70.
Paradossi G Cavalieri F Chiessi E Spagnoli C Cowman MK 《Journal of materials science. Materials in medicine》2003,14(8):687-691
In this paper, we present some new case examples where the chemical versatility of poly (vinyl alcohol) (PVA) can be used for potential biomedical applications. PVA, the polymeric material used for designing new nanostructured devices, is water soluble, biocompatible and has excellent physical properties. We point out the possibility of obtaining wall-to-wall chemical hydrogels as well as microgels without diminishing the biocompatibility available in the starting PVA material. Injectability is another important factor to take into account in controlled drug delivery for gene therapy. In this respect, in this paper, established and more innovative methods are prospected in order to obtain particles with dimensions suitable for these applications. 相似文献