A secure and lightweight ad-hoc routing algorithm for personal networks

Over the past few years, there has been increasing interest in utilizing Personal Area Networks (PANs) to offer users innovative and personalized services. This interest is a consequence of the widespread use of mobile devices such as laptops, mobile phones, PDAs, digital cameras, wireless headsets, etc. to carry out a variety of user-centric tasks. The PAN itself is built upon an ad-hoc network where devices trust their neighbors to route their packets. The cooperative nature of ad-hoc networks allows malicious nodes to easily cripple the network by inserting false route information, replaying old messages, modifying messages of other nodes, etc. An applicable area still under research, and the focus of this paper, is secure routing protocols for ad-hoc networks. To achieve availability in the PAN, the routing protocol used must be robust against both dynamically changing topology and malicious attacks. However, the heterogeneous nature of Personal Network (PN) devices means that traditional security mechanisms are too resource intensive to be sufficient by themselves. This paper describes a new ad-hoc secure routing protocol for Personal Networks (PNs), suitable in a limited multi-hop scenario. This protocol is based on ADOV and relies on efficient cryptographic primitives to safeguard the security and privacy of PN users. Following that, a number of attacks in the area of ad-hoc networks are discussed, and it is shown that the new algorithm protects against multiple un-coordinated active attackers, in spite of compromised nodes in the network

Research Issues in Ad-Hoc Distributed Personal Networking

This paper discusses the research issues that need to be addressed in order to create a personal distributed environment where people interact with various companion, embedded, or invisible computers not only in their close vicinity but potentially anywhere. These systems are called personal networks (PNs). They constitute a category of distributed systems with very specific characteristics. They are configured in an ad hoc fashion, as the opportunity and the demand arise, to support personal applications. PNs consist of communicating clusters of personal digital devices, devices shared with other people and even infrastructure-based systems. At the heart of a PN is a core Personal Area Network (PAN), which is physically associated with the owner of the PN. Unlike the present PANs that have a geographically limited coverage, the Personal Operating Space, PNs have an unrestricted geographical span, and incorporate devices into the personal environment regardless of their geographic location. In order to do this they need the services of infrastructure-based networks and ad-hoc networks to extend their reach. A PN extends and complements the concept of pervasive computing. We show that PNs introduce new design challenges due to the heterogeneity of the involved technologies, the need for self-organization, the dynamics of the system composition, the application-driven nature, the co-operation with infrastructure-based networks, and the security hazards. We discuss the impact of these problems on network design, assess present and proposed solutions, and identify the research issues

Intrinsic deviations in fluorescence yield detected x ray absorption spectroscopy the case of the transition metal L 2,3 edges

Fluorescence yield FY detected x ray absorption spectra XAS of 3d transition metal ions are calculated from the integrated 2p3d resonant x ray emission spectra. The resulting FY XAS spectra are compared with the normal XAS spectra corresponding to the absorption cross section and significant deviations between the two spectra are found. This implies that the assumption that the FY XAS spectrum identifies with the XAS spectrum is disproved. Especially for the early transition metal systems the differences between the FY XAS and XAS are large, due to the opening of inelastic decay channels from selected x ray absorption final states. The theoretical calculations show that the difference between FY detection and XAS is largest for the detection in depolarized geometry. The calculations are compared with experimental spectra for oxides and coordination compounds for Fe2C, Co2C and Ni2C systems. The implications for the sum rules in XAS and magnetic circular dichroism experiments are discusse

Identité de l'image de sport

L'image de sport et le mouvement depuis les premières chronophotographies. Les mises en scène du sport et le public. L'image de sport, un objet d'étude en devenir. Propositions d'outils d'analyse

Synergistic activation of non-rectifying small-conductance chloride channels by forskolin and phorbol esters in cell-attached patches of the human colon carcinoma cell line HT-29cl.19A

Cell-attached patch-clamp studies with the human colon carcinoma HT-29cl.19A cells revealed a small chloride channel with a unitary conductance of 6.5 pS at 70 mV and 4.6 pS at -70 mV clamp potential after cAMP was increased by activation of adenylyl cyclase by forskolin. Usually channels inactivated upon patch excision, but in a few excised patches the channels stayed active and displayed a linear I/V relation in symmetrical (150 mmol/l) chloride solutions with a conductance of 7.5 pS. A 16-fold increase in channel incidence was observed when forskolin and phorbol 12,13-dibutyrate (PDB) were present together. The open probability was voltage-independent and was not different in the presence of forskolin plus PDB or with forskolin alone. The conductance sequence of the channel as deduced from outward currents carried by five different anions including chloride was: Cl->Br->NO3 ->gluconate > I-. The permeability sequence deduced from the reversal potentials was NO3 -≥Br->Cl->I->gluconate. With iodide in the pipette the conductance decreased strongly. Moreover, the inward current was reduced by 61%, indicating a strong inhibition of the chloride efflux by iodide. Similarly, the forskolin-induced increase of the short-circuit current (Isc) in confluent filter-grown monolayers was strongly reduced by iodide in the apical perfusate. Iodide also increased the fractional resistance of the apical membrane and repolarized the membrane potential, indicating an inhibitory action on the forskolin-induced increase of the apical chloride conductance. The PDB-induced Isc was also reduced by iodide, suggesting that the same chloride conductance is involved in the forskolin and in the PDB response. The results suggest that forskolin via cAMP-dependent protein kinase and PDB via protein kinase C regulate the same non-rectifying small-conductance chloride channels in the HT-29cl.19A cells

Milieueffectrapport Structuurvisie Infrastructuur en Ruimte

Ten behoeve van de besluitvorming over de Structuurvisie Infrastructuur en Ruimte is een planMER opgesteld. Deze biedt informatie over de milieueffecten van het nieuwe beleid, zodat het milieubelang volwaardig kan worden meegewogen in de besluitvorming. Bovendien is in het planMER een zogenaamde voortoets opgenomen, waarin mogelijke consequenties voor de instandhouding van de strikt beschermde Natura2000-gebieden zijn verkend