Towards Greater Respect for the Users Privacy in communication technologies.

Wireless Local Area Networks (WLANs) are an emerging technology that have become increasingly popular in several locations such as businesses, educational institutions, Internet cafes, airports, etc. Since the first time WLANs appeared, users were able to communicate and exchange information and data from anywhere, access cloud services anytime, regardless of their geographic position or time. Due to their importance, WLANs which have been popular by the WiFi technology, are becoming more and more vulnerable to attacks and threats from other parties, where attackers can retrieve important data by capturing transmitted packets through access points, in which they can extract the MAC address of the transmitter, and thus be able to record the movements of the transmitter over time even when the system uses encryption as layer 2 headers, particularly the MAC address which uniquely identifies a mobile station is not encrypted. Existing solutions to this privacy breach aim at using pseudonyms to avoid using the same MAC address and also introduce silent periods to make it difficult for an attacker to track users. Due to the downside of the existing solutions, in this thesis we propose two contributions, the first contribution consists of a mathematical model to quantify the privacy and a decentralized algorithm that use silent periods (SPs) to change the MAC address, and allow users to attain their desired levels of privacy while lowering its effect on the QoS perceived by them. The introduction of silent periods may have negative effects on some applications particularly for those with iAbstract constraints on bandwidth and delay such as video streaming. Therefore, in our second contribution, we propose an enhanced silent-period-based solution that allows to maximize the perceived QoS for a preset privacy. Our solutions offer users the best trade-off between privacy and QoS. We experimented our proposal with a set of numerical simulations. The obtained results demonstrated the efficiency of the proposed solution

Mineralogical and chemical characterization of DD3 kaolin from the east of Algeria

The mineralogical and chemical characteristics, based on X-ray diffraction (XRD) and scanning electron microscopy, of a kaolin known as DD3, from eastern Algeria were examined in the present study. The results showed that kaolin DD3 has an alumina content of 39%. The SiO2/Al2O3 molar ratio of 2.14 is close to that of a pure halloysite. The hematite concentration is relatively large and the flux oxides ratios remain as acceptable impurities. Microscopic observations showed a predominant tubular halloysite phase, flattened hexagonal platelets corresponding to the presence of kaolinite and its polymorphs (nacrite, dickite), and hydrated alumina. The SiO2/Al2O3 molar ratio and tubular DD3 suggest possible uses in technical ceramics and nanotechnology applications. Analysis by XRD revealed the presence of many phases. Thermal treatment at 450 °C and chemical treatment with HCl confirmed the presence of halloysite. The inclusion in the clay of organic molecules (dimethylsulfoxide (DMSO), DMF, and diluted glycerol) showed that the DMSO led to expansion of the inter-planar distance. The intercalation by DMSO molecules resulted in a shift of the basal peak from 10 to 11.02 Å and partial displacement of the peak from 3.35 to 3.65 Å. These two peaks are characteristic of halloysite. The presence of residual nacrite was also confirmed by the shift of the peak observed at 3.35 Å. A full analysis of the XRD patterns using the Match software, based on these results, showed that the DD3 clay consists of >60% halloysite

Dromedary camel milk proteins, a source of peptides having biological activities – A review

Many useful properties are assigned to camel (Camelus dromedarius) milk, which is traditionally used for the treatment of tuberculosis, gastroenteritis, and allergy in many countries. Some amino acid sequences, which are encrypted in the camel proteins, may play a beneficial role in human health once they are released from milk either in vivo during normal digestion or by proteolysis with purified enzymes or during bacterial fermentation. Similar to the bovine milk counterparts, camel milk bioactive peptides may display a variety of potential activities that were almost always unveiled from in vitro analyses: antimicrobial, anti-oxidative, anti-hypertensive, anti-inflammatory, and immunomodulatory activities. Today, there is a growing interest for bioactive peptides generated from camel milk. This paper reviews available data on the potential biological activities of the camel milk proteins and their peptides liberated either during milk fermentation with proteolytic bacterial strains or by enzyme hydrolysis with specific proteases or simulated gastro-intestinal digestion