Multimedia Content Distribution in Hybrid Wireless Networks using Weighted Clustering

Fixed infrastructured networks naturally support centralized approaches for group management and information provisioning. Contrary to infrastructured networks, in multi-hop ad-hoc networks each node acts as a router as well as sender and receiver. Some applications, however, requires hierarchical arrangements that-for practical reasons-has to be done locally and self-organized. An additional challenge is to deal with mobility that causes permanent network partitioning and re-organizations. Technically, these problems can be tackled by providing additional uplinks to a backbone network, which can be used to access resources in the Internet as well as to inter-link multiple ad-hoc network partitions, creating a hybrid wireless network. In this paper, we present a prototypically implemented hybrid wireless network system optimized for multimedia content distribution. To efficiently manage the ad-hoc communicating devices a weighted clustering algorithm is introduced. The proposed localized algorithm deals with mobility, but does not require geographical information or distances.Comment: 2nd ACM Workshop on Wireless Multimedia Networking and Performance Modeling 2006 (ISBN 1-59593-485

Soil carbon sequestration of organic crop and livestock systems and potential for accreditation by carbon markets

During a two-day RTOACC workshop hosted by the Research Institute of Organic Agriculture (FiBL), participants discussed the potential for organic agriculture in carbon markets and the need to develop strategies for the role of organic agriculture in climate policy. To move in this direction requires quantifying and raising recognition of the mitigation potential of organic agriculture. Thus the participants also looked at available data and began a process of identifying data gaps. In doing so, they presented the related ongoing work of their organizations and drew conclusions for the further orientation and actions of the RTOACC. The following synthesizes the discussions, reports and outcomes of the workshop

What Drives Taxi Drivers? A Field Experiment on Fraud in a Market for Credence Goods

Credence goods are characterized by informational asymmetries between sellers and consumers that invite fraudulent behavior by sellers. This paper presents the results of a natural field experiment on taxi rides in Athens, Greece, set up to measure different types of fraud and to examine the influence of passengers’ presumed information and income on the extent of fraud. Results reveal that taxi drivers cheat passengers in systematic ways: Passengers with inferior information about optimal routes are taken on longer detours while asymmetric information on the local tariff system leads to manipulated bills. Higher income seems to lead to more fraud.credence goods, expert services, natural field experiment, taxi rides, fraud, asymmetric information

What drives taxi drivers? A field experiment on fraud in a market for credence goods

Credence goods are characterized by informational asymmetries between sellers and consumers that invite fraudulent behavior by sellers. This paper presents the results of a natural field experiment on taxi rides in Athens, Greece, set up to measure different types of fraud and to examine the influence of passengers’ presumed information and income on the extent of fraud. Results reveal that taxi drivers cheat passengers in systematic ways: Passengers with inferior information about optimal routes are taken on longer detours while asymmetric information on the local tariff system leads to manipulated bills. Higher income seems to lead to more fraud.Credence goods, expert services, natural field experiment, taxi rides, fraud, asymmetric information

One-dimensional itinerant interacting non-Abelian anyons

We construct models of interacting itinerant non-Abelian anyons moving along one-dimensional chains. We focus on itinerant Ising (Majorana) and Fibonacci anyons, which are, respectively, related to SU(2)_2 and SU(2)_3 anyons and also, respectively, describe quasiparticles of the Moore-Read and Z_3-Read-Rezayi fractional quantum Hall states. Following the derivation of the electronic large-U effective Hubbard model, we derive effective anyonic t-J models for the low-energy sectors. Solving these models by exact diagonalization, we find a fractionalization of the anyons into charge and (neutral) anyonic degrees of freedom -- a generalization of spin-charge separation of electrons which occurs in Luttinger liquids. A detailed description of the excitation spectrum can be performed by combining spectra for charge and anyonic sectors. The anyonic sector is the one of a squeezed chain of localized interacting anyons, and hence is described by the same conformal field theory (CFT), with central charge c=1/2 for Ising anyons and c=7/10 or c=4/5 for Fibonacci anyons with antiferromagnetic or ferromagnetic coupling, respectively. The charge sector is the spectrum of a chain of hardcore bosons subject to phase shifts which coincide with the momenta of the combined anyonic eigenstates, revealing a subtle coupling between charge and anyonic excitations at the microscopic level (which we also find to be present in Luttinger liquids), despite the macroscopic fractionalization. The combined central charge extracted from the entanglement entropy between segments of the chain is shown to be 1+c, where c is the central charge of the underlying CFT of the localized anyon (squeezed) chain.Comment: 19 pages, 18 figure