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

Thermal bulk polymerization of cholesteryl acrylate

The thermal bulk polymerization of cholesteryl acrylate was carried out in the solid phase, the mesomorphic phase, and the liquid phase to study the effect of monomer ordering on polymerization rate and polymer properties. The rate increased with decreasing ordering (or enhanced mobility) of the monomer. Formation of inhibitive by-products during the polymerization limited conversions to 35%. The sedimentation constant S0 = 6.2 S was the same for the polymers obtained in the three phases. The weight-average molecular weight (w) was 480,000 as determined by ultracentrifugation. Poly-(cholesteryl acrylate) formed in bulk is randomly coiled when dissolved in tetrahydrofuran. The thermal properties of the monomer are given

Low work function of the (1000) Ca2N surface

Polymer diodes require cathodes that do not corrode the polymer but do have low work function to minimize the electron injection barrier. First-principles calculations demonstrate that the work function of the (1000) surface of the compound Ca2N is half an eV lower than that of the elemental metal Ca (2.35 vs. 2.87 eV). Moreover its reactivity is expected to be smaller. This makes Ca2N an interesting candidate to replace calcium as cathode material for polymer light emitting diode devices.Comment: 3 pages, 4 figures, accepted by J. Appl. Phy

A pattern-recognition theory of search in expert problem solving

Understanding how look-ahead search and pattern recognition interact is one of the important research questions in the study of expert problem-solving. This paper examines the implications of the template theory (Gobet & Simon, 1996a), a recent theory of expert memory, on the theory of problem solving in chess. Templates are "chunks" (Chase & Simon, 1973) that have evolved into more complex data structures and that possess slots allowing values to be encoded rapidly. Templates may facilitate search in three ways: (a) by allowing information to be stored into LTM rapidly; (b) by allowing a search in the template space in addition to a search in the move space; and (c) by compensating loss in the "mind's eye" due to interference and decay. A computer model implementing the main ideas of the theory is presented, and simulations of its search behaviour are discussed. The template theory accounts for the slight skill difference in average depth of search found in chess players, as well as for other empirical data

Preparation of a Resorbable Osteoinductive Tricalcium Phosphate Ceramic

Over the past decade we have demonstrated numerous times that calcium phosphates can be rendered with osteoinductive properties by introducing specific surface microstructures1. Since most of these calcium phosphates contained hydroxyapatite, they are either slowly or not resorbable2. Resorbability is an often sought after characteristic of calcium phosphates so that they can be gradually replaced by newly formed bone. The objective of this study was to prepare a resorbable surface microstructured tricalcium phosphate (TCP) ceramic and evaluate its osteoinductive property and resorption rate after intramuscular implantation in dogs. This material was then compared to the established and slowly resorbable osteoinductive biphasic calcium phosphate ceramic (BCP)

Innovative financing mechanisms for sustainable ecosystem management

The increasing human influence on ecosystems and the ensuing unsustainable exploitation and degradation has led in many places to depletion and loss of function of these ecosystems. These problems cannot be solved by (innovative) financing mechanisms, as the causes do not lie in a lack of financing mechanisms. Although decifit in funding in general is an important issue - the amount of finance available for ecosystems and biodiversity falls short of the funding neede