Establishing Trust Through Anonymous and Private Information Exchange Over Personal Networks

Security and privacy in Personal Networks constitute a major challenge for designers and implementers. The deployment of novel services over a collaborative environment where users share their resources and profiles create higher demands on security and privacy requirements. In this paper, the authors address the issue of privacy-enabled, secure personal information exchange among participants of a Personal Networks federation, in order to establish trust. The paper proposes a novel model based on the separation of user ID information from personal preferences and user status information. The proposed model is able to ensure privacy through anonymity over personal data exchange, while it incorporates mechanisms for the detection and confronting of malicious behavior, and resilience against attacks. A proof of concept based on an actual implementation is provided. Further, discussion is presented on the issues that need to be tackled in order to incorporate the proposed model in a standard PN architecture.     

FBG-based monitoring of solidification strain development in a microstereolithography photocurable resin

The shrinkage characteristics of photocurable resins are critical factors in final three-dimensional microstructures fabricated using micro-stereolithography. In this work, an approach in measuring in situ solididification strains in a photopolymer, frequently used for the fabrication of micro-parts, is presented. The photopolymer used in the present investigation is a multifunctional acrylate-based resin with 1% photo-initiator used in the past for single and two-photon stereolithography. The resulted strain profile build up is monitored via the use of an embedded fiber Bragg grating (FBG) into a cylindrical test specimen as the photopolymer is exposed to stepwise applied UV-light irradiation. The obtained results demonstrate the potential of strain levels monitoring as a function of laser light exposure and scanning conditions in microstereolithography photocurable resins.     

Software acceleration techniques for the simulation of scanning electron microscope images

A scanning electron microscope (SEM) simulator was developed based on the models used in the MONSEL software. This simulator extends earlier work by introducing an object-oriented framework and adding optimization methods based on precomputation of electron trajectories. Several optimizations enable speedup by factors of 5-100 on a single processor over unoptimized simulations without introducing additional approximations. The speedup for a particular surface depends on the self-similarity of the surface at the scale of the electron penetration depth. We further accelerate by parallelizing the calculations for a total speedup of about 100-2000 on 30 processors. The goal of this work was to create a system capable of simulating a quantitatively accurate SEM image of a relatively unconstrained surface. Results of this work include simulation software, optimization algorithms, performance measurements with various optimizations, and examples of simulated images.     

LIDAR: a protocol for stable and energy-efficient clustering of ad-hoc multihop networks

Clustering has been proposed as a promising method for simplifying the routing process in mobile ad hoc networks (MANETs). The main objective in clustering is to identify suitable node representatives, i.e. cluster heads (CHs) to store routing and topology information; CHs should be elected so as to maximize clusters stability, that is to prevent frequent cluster re-structuring. Since CHs are engaged on packet forwarding they are prone to rapidly drop their energy supplies, hence, another important objective of clustering is to prevent such node failures. Recently proposed clustering algorithms either suggest CH election based on node IDs (nodes with locally lowest ID value become CHs) or take into account additional metrics (such as energy and mobility) and optimize initial clustering. Yet, the former method is biased against nodes with low IDs (which are likely to serve as CHs for long periods and therefore run the risk of rapid battery exhaustion). Similarly, in the latter method, in many situations (e.g. in relatively static topologies) re-clustering procedure is hardly ever invoked; hence initially elected CHs soon suffer from energy drainage. Herein, we propose LIDAR, a novel clustering method which represents a major improvement over alternative clustering algorithms: node IDs are periodically re-assigned so that nodes with low mobility rate and high energy capacity are assigned low ID values and, therefore, are likely to serve as CHs. Therefore, LIDAR achieves stable cluster formations and balanced distribution of energy consumption over mobile nodes. Our protocol also greatly reduces control traffic volume of existing algorithms during clustering maintenance phase, while not risking the energy availability of CHs. Simulation results demonstrate the efficiency, scalability and stability of our protocol against alternative approaches.     

Digital cities of the future: Extending @home assistive technologies for the elderly and the disabled

In the digital city of the future there is the vision of seamless virtual and physical access for every home and between each home and the workplace, as well as critical city infrastructure such as the post office, the bank, hospitals, transportation systems, and other entities. This paper provides an overview of technical and other issues in extending at home (@home) assistive technologies for the elderly and the disabled. The paper starts by giving a vision of what this city is supposed to look like and how a human is to act, navigate and function in it. A framework for extending assistive technologies is proposed that considers individuals belonging to special groups of interest and locations other than their home. Technology has already reached the state of ubiquitous and pervasive sensor devices measuring everything, from temperature to human behavior. Implanting intelligence into and connecting such devices will be of immense use in preventive healthcare, security in industrial installations, greater energy efficiency, and numerous other applications. The paper reviews enabling technologies that exist and focuses on healthcare applications that support a longer and higher quality of life at home for the elderly and the disabled. It discusses intelligent platforms involving agents, context-aware and location-based services, and classification systems that enable advanced monitoring and interpretation of patient status and optimization of the environment to improve medical assessments. The paper concludes with a discussion of some of the challenges that exist in extending @home assistive technologies to @city assistive technologies.     

Scheduling and Resource Allocation Strategy for OFDMA Systems Over Time-Varying Channels

A cross-layer scheduling and resource allocation (SRA) strategy for an adaptive modulation and coding (AMC) based orthogonal frequency multiple access (OFDMA) system is proposed. The objective of this paper is to maximize the system throughput as a function of the bit error rate (BER) and the spectral efficiency based on the selected modulation and coding schemes (MCSs). The proposed strategy contains two main algorithms. Firstly, the scheduling algorithm that aims to maximize the average system throughput by arranging the users in distinct queues according to their priorities and selecting the best user of each queue individually in order to guarantee a fair user service amongst different priority levels. Secondly, the resource allocation algorithm that allocates the user, bit and power based on the channel conditions of the scheduling users and the transmission power constraints. The transmitter of the investigated AMC-OFDMA system at the assigned base station (BS) divides the transmitted OFDMA frame into sub-channels and assigns each sub-channel to a scheduled user. In this paper, we compare the performance of the proposed SRA with the conventional first in first out (FIFO) queuing based scheduling and resource allocation strategies used for an AMC-OFDMA system. The simulation results show that the investigated AMC-OFDMA system based on the proposed SRA strategy outperforms the conventional approaches.     

Lipidomic Analysis of Serum from High Fat Diet Induced Obese Mice

Lipid metabolites regulate fatty acid and glucose homeostasis. The intention of the current study is to identify circulating lipid species, which are altered in rodent obesity and strongly correlate with the classically measured metabolites glucose, triglycerides, and cholesterol. Mice fed a high fat diet (HFD) for 14 weeks have increased body weight and fasting glucose. Serum triglycerides are not altered, while cholesterol tends to be increased. Accordingly, major cholesteryl ester (CE) species and free cholesterol are not significantly raised in obesity while minor metabolites, including CE 20:3 and CE 18:3, are increased or reduced, respectively. Distinct sphingomyelin (SM) species are elevated while ceramides are not raised. Phosphatidylinositol (PI) species, including PI 34:1, are raised while others are decreased. PI 34:1 strongly correlates with fasting glucose and proinsulin levels. Phosphatidylcholine (PC) 26:0, 40:2, and 40:5, which are induced in obesity, correlate with cholesterol. PC 38:4 and PC 40:6 are also raised in fat fed mice and positively correlate with fasting glucose. Lysophosphatidylcholine (LPC) species are also changed in obesity and the already shown reduction of LPC 16:1 has been confirmed. LPC 22:4, which is increased, correlates with serum cholesterol. The data indicate that circulating levels of various lipid species are changed in the obesity model studied and some of them are strongly associated with classically measured metabolites.     

Development and Validation of an ETAAS Method for the Determination of Tin in Canned Tomato Paste Samples

The determination of tin in canned food became very important in the last few years since it gives information about the contamination process helping to increase canned food quality and safety. The present work describes the development of a method for the determination of tin in canned tomato paste by electrothermal atomic absorption spectrometry in order to investigate the influents of (1) the industrial sample pretreatment procedure of canned tomato paste and (2) the type of materials used in packaging, on the total concentration of tin in canned tomato paste samples. For method validation, precision (repeatability and reproducibility) and accuracy (by recovery tests) have been assessed as performance criteria. The calculated recoveries ranged between 87.9% and 91.9%. The calculated expanded uncertainties based on the EURACHEM/CITAC Guidelines achieved from three different concentration levels were also calculated. The obtained results indicated that the method is efficiently and properly implemented. The validated method was applied for tin concentration determination in canned tomato paste purchased from the local market. In all analyzed samples, tin concentrations levels were lower than the maximum permissible value recommended by the European Regulation.