Discovering periodic patterns of nodal encounters in mobile networks

Routing in Delay Tolerant Networks is very challenging because of frequent disconnections. One cause of disconnection is node movement. Disconnections can be overcome by finding a set of sequential opportunistic encounters between pairs of mobile nodes. These encounters can be used for message forwarding and delivery. In this context, understanding user mobile behaviour is essential to design effective and efficient network protocols. This paper presents a generic methodology to model and find periodic encounter patterns by using the auto-persistence function and detection techniques derived from it. From the studies on four real mobility traces, we are able to detect strong weekly periodic encounter patterns with an accuracy of up to 100%. The experimental results show that periodic encounter patterns in real mobility traces do not last long, e.g., years, because they are interrupted by unexpected events from time to time. Nonetheless our experimental results show that those periodic encounters can still last up to a few months. Furthermore, we show that, for some of the mobility traces, the network formed by periodic encounters forms a small-world structure.     

Analysis of Secure Mobile Grid Systems: A systematic approach

Developing software through systematic processes is becoming more and more important due to the growing complexity of software development. It is important that the development process used integrates security aspects from the first stages at the same level as other functional and non-functional requirements. Systems which are based on Grid Computing are a kind of systems that have clear differentiating features in which security is a highly important aspect. The Mobile Grid, which is relevant to both Grid and Mobile Computing, is a full inheritor of the Grid with the additional feature that it supports mobile users and resources. A development methodology for Secure Mobile Grid Systems is proposed in which the security aspects are considered from the first stages of the life-cycle and in which the mobile Grid technological environment is always present in each activity. This paper presents the analysis activity, in which the requirements (focusing on the grid, mobile and security requirements) of the system are specified and which is driven by reusable use cases through which the requirements and needs of these systems can be defined. These use cases have been defined through a UML-extension for security use cases and Grid use cases which capture the behaviour of this kind of systems. The analysis activity has been applied to a real case.     

Core–shell nanowires: From the ensemble to single-wire characterization

Recent investigations of core–shell nanowires using synchrotron radiation techniques deduced the average structural parameters of heterostructure core–shell nanowires. Here, we report on first results and discuss the problems arising when measuring such complex nanostructures by using nanofocusing X-ray techniques. InAs/InAsP core–shell nanowires exhibit a certain bending, the origin of which is described using finite element simulations assuming a displacement of the core, and a gradient in the chemical composition of the wire’s shell.     

Suppression of Low-order Current Harmonics in AC Motor Drives via Multiple Reference Frames Based Control Algorithm

A novel control algorithm devoted to remove undesired low-order current harmonics in AC motor drives is presented in this article. The proposed control algorithm combines a suitable multiple reference frame synchronous harmonic estimator and multiple reference frame vector control implementation to suppress the undesired harmonics contained in the motor stator currents. This control technique can handle positive-, negative-, and zero-sequence sets, keeping a satisfying dynamic behavior. The control technique has been evaluated by numerical simulations and experimentally tested on a permanent magnet synchronous motor drive.     

Extraction of metals from automotive shredder residue:Preliminary results of different leaching systems

The study is focused on the extraction of valuable metals from automotive shredder residue (ASR) by different leaching solutions. First, ASR samples were roasted at 600 °C to simulate a thermal treatme...     

Evaluation of Osseointegration of Titanium Alloyed Implants Modified by Plasma Polymerization

By means of plasma polymerization, positively charged, nanometre-thin coatings can be applied to implant surfaces. The aim of the present study was to quantify the adhesion of human bone cells in vitro and to evaluate the bone ongrowth in vivo, on titanium surfaces modified by plasma polymer coatings. Different implant surface configurations were examined: titanium alloy (Ti6Al4V) coated with plasma-polymerized allylamine (PPAAm) and plasma-polymerized ethylenediamine (PPEDA) versus uncoated. Shear stress on human osteoblast-like MG-63 cells was investigated in vitro using a spinning disc device. Furthermore, bone-to-implant contact (BIC) was evaluated in vivo. Custom-made conical titanium implants were inserted at the medial tibia of female Sprague-Dawley rats. After a follow-up of six weeks, the BIC was determined by means of histomorphometry. The quantification of cell adhesion showed a significantly higher shear stress for MG-63 cells on PPAAm and PPEDA compared to uncoated Ti6Al4V. Uncoated titanium alloyed implants showed the lowest BIC (40.4%). Implants with PPAAm coating revealed a clear but not significant increase of the BIC (58.5%) and implants with PPEDA a significantly increased BIC (63.7%). In conclusion, plasma polymer coatings demonstrate enhanced cell adhesion and bone ongrowth compared to uncoated titanium surfaces.     

Chiral Resolution and Pharmacological Characterization of the Enantiomers of the Hsp90 Inhibitor 2‐Amino‐7‐[4‐fluoro‐2‐(3‐pyridyl)phenyl]‐4‐methyl‐7,8‐dihydro‐6H‐quinazolin‐5‐one Oxime

Heat‐shock protein 90 (Hsp90) is a molecular chaperone involved in the stabilization of key oncogenic signaling proteins, and therefore, inhibition of Hsp90 represents a new strategy in cancer therapy. 2‐Amino‐7‐[4‐fluoro‐2‐(3‐pyridyl)phenyl]‐4‐methyl‐7,8‐dihydro‐6H‐quinazolin‐5‐one oxime is a racemic Hsp90 inhibitor that targets the N‐terminal adenosine triphosphatase site. We developed a method to resolve the enantiomers and evaluated their inhibitory activity on Hsp90 and the consequent antitumor effects. The (S) stereoisomer emerged as a potent Hsp90 inhibitor in biochemical and cellular assays. In addition, this enantiomer exhibited high oral bioavailability in mice and excellent antitumor activity in two different human cancer xenograft models.