An analysis of the lifetime of OLSR networks

The Optimized Link State Routing (OLSR) protocol is a well-known route discovery protocol for ad-hoc networks. OLSR optimizes the flooding of link state information through the network using multipoint relays (MPRs). Only nodes selected as MPRs are responsible for forwarding control traffic. Many research papers aim to optimize the selection of MPRs with a specific purpose in mind: e.g., to minimize their number, to keep paths with high Quality of Service or to maximize the network lifetime (the time until the first node runs out of energy). In such analyzes often the effects of the network structure on the MPR selection are not taken into account. In this paper we show that the structure of the network can have a large impact on the MPR selection. In highly regular structures (such as grids) there is even no variation in the MPR sets that result from various MPR selection mechanisms. Furthermore, we study the influence of the network structure on the network lifetime problem in a setting where at regular intervals messages are broadcasted using MPRs. We introduce the ’maximum forcedness ratio’, as a key parameter of the network to describe how much variation there is in the lifetime results of various MPR selection heuristics. Although we focus our attention to OLSR, being a widely implemented protocol, on a more abstract level our results describe the structure of connected sets dominating the 2-hop neighborhood of a node

Methods for analyzing routing games:Information design, risk-averseness, and Braess's paradox

We study ways in which information about traffic networks can be used to achieve social objectives, such as decreasing experienced travel time. First we study how behaviour of drivers changes when the total amount of traffic changes. We give an exact characterization of this change in behaviour, which is computationally feasible to obtain. We then use insights obtained from deriving this characterization to consider the difficult problem of detecting Braess’s paradox in a network, where removal of a road leads to decreased travel time for all drivers. We give some new, efficient methods for detecting this phenomenon, and also show that in some cases the existence of Braess’s paradox in a network may be a good thing. Next we study traffic networks with potentially unpredictable travel costs. We investigate a scenario a central planner can strategically withhold information from drivers on the road to prevent congestion and benefit all road users. However, the planner’s strategy depends upon the prior beliefs about the roads that the drivers adhere to, and we study how a planner can derive these beliefs by observing the behaviour of the drivers.Finally we study the scenario where drivers are risk-averse, and can thus avoid roads that are quick on average, but can be significantly slowed in some cases

Physiology and Genetics of Drought Tolerance in Cowpea and Winter Wheat

In the wake of rising temperatures, erratic rainfall, and declining ground water table, breeding for drought tolerance in food crops has become a top priority throughout the world. Phenotyping a large population of breeding lines for drought tolerance is time-consuming and often unreliable due to multiple possible mechanisms involved. In cowpea (Vigna unguiculata L. Walp), a box-screening method has been used to partition the confounding effects that shoot and root traits have on drought tolerance by restricting root growth and providing a homogeneous soil moisture environment across genotypes. Nonetheless, multiple mechanisms of shoot drought tolerance have been reported which further complicate phenotyping. In winter wheat (Triticum aestivum L.), canopy temperature depression (CTD) has been proposed as a good indicator of drought tolerance. The recent development of low-cost thermal imaging devices could enable high-throughput phenotyping of canopy temperature. While CTD can be an indicator of overall plant water status, it can be confounded by high stomatal resistance, which is another seemingly contradictory mechanism of drought tolerance. The objectives of this study were to explore the physiological basis and genetics of the two mechanisms of shoot drought tolerance previously reported in cowpea and to develop and evaluate a method of high-throughput phenotyping of drought tolerance in winter wheat using thermal imaging. In cowpea, a legume well known for its tight stomatal control, no differences in gas exchange between drought tolerant and susceptible genotypes were observed. A unifoliate stay-green trait was discovered that segregates as a single recessive gene. However, it did not correlate with trifoliate necrosis or overall drought tolerance. In winter wheat, CTD did not always correlate with yield under rainfed conditions. One drought-tolerant cultivar, in particular, had the hottest canopy temperature, possibly because it was able to conserve moisture by closing its stomata whereas another closely related drought-tolerant cultivar had the coolest canopy temperature. Therefore, it appears that no single method of phenotyping for drought tolerance can be broadly applied across all genotypes of a given species due to possible contrasting mechanisms of drought-tolerance and environmental differences

Wardrop equilibrium and Braess's paradox for varying demand

This work explores the relationship between the set of Wardrop equilibria~(WE) of a routing game, the total demand of that game, and the occurrence of Braess's paradox~(BP). The BP formalizes the counter-intuitive fact that for some networks, removing a path from the network decreases congestion at WE. For a single origin-destination routing games with affine cost functions, the first part of this work provides tools for analyzing the evolution of the WE as the demand varies. It characterizes the piece-wise affine nature of this dependence by showing that the set of directions in which the WE can vary in each piece is the solution of a variational inequality problem. In the process we establish various properties of changes in the set of used and minimal-cost paths as demand varies. As a consequence of these characterizations, we derive a procedure to obtain the WE for all demands above a certain threshold. The second part of the paper deals with detecting the presence of BP in a network. We supply a number of sufficient conditions that reveal the presence of BP and that are computationally tractable. We also discuss a different perspective on BP, where we establish that a path causing BP at a particular demand must be strictly beneficial to the network at a lower demand. Several examples throughout this work illustrate and elaborate our findings

Burgers bewegen in de buurt:de invloed van een beweegvriendelijke inrichting van openbare ruimte op burgerparticipatie in de wijk

Er vindt een verschuiving plaats van verzorgingsstaat tot participatiemaatschappij (RIVM, 2014). Er wordt van de burgers verlangd zich actief te mengen in kwesties en mee te bouwen aan een leefbare gemeente. In een poging maatschappelijke problemen te verminderen tracht de overheid burgerparticipatie te vergroten, onder andere door een Beweegvriendelijke Inrichting van de Openbare Ruimte (BIOR) (Gemeente Groningen, 2014). Dit is een initiatief waarin de openbare ruimte is ingericht om burgers te stimuleren, faciliteren en uit te dagen om te spelen, bewegen en te ontmoeten (Cammelbeeck, Engbers, Kunen & L'abée, 2013). Hieruit volgt de probleemstelling: “Wat is de relatie tussen BIOR en burgerparticipatie en wat is de rol van sociale cohesie in dit verband?

First Steps Towards the Automatic Construction of Argument-Diagrams from Real Discussions

This paper presents our efforts to create argument structures from meeting transcripts automatically. We show that unit labels of argument diagrams can be learnt and predicted by a computer with an accuracy of 78,52% and 51,43% on an unbalanced and balanced set respectively. We used a corpus of over 250 argument diagrams that was manually created by applying the Twente Argument Schema. In\ud this paper we also elaborate on this schema and we discuss applications and the role we foresee the diagrams to play

Soil and Mold Influences on Fe and Zn Concentrations of Sorghum Grain in Mali, West Africa

Iron (Fe) and zinc (Zn) deficiencies affect an estimated 3 billion people worldwide and are linked with cognitive and physical impairments, maternal and child mortality rates, and decreased adult work activity. To combat this "hidden" hunger, plant breeders in Mali are working to increase sorghum grain Fe and Zn concentrations. The objective of this study was to investigate soil and mold influences that affect Fe and Zn uptake and accumulation in sorghum grain. In southern Mali, soils from participatory sorghum variety trials and areas of different parent material and proximity to Shea (Vitellaria paradoxa) trees were analyzed for diethylenetriaminepentaacetic acid (DTPA)-extractable Zn and related soil properties, and sorghum grain was analyzed for Zn concentration. An inoculation trial was also performed at College Station, TX to determine if sorghum grain infected by the mold Curvularia lunata significantly increased grain Fe concentrations. DTPA-extractable Zn concentration was highly variable with high concentrations found in soils under Shea tree canopies with high pH and organic carbon and derived from mafic, high Zn-content parent material. However, these high concentrations did not significantly affect grain Zn concentrations in sorghum grown outside of the canopy. Groundnut grown underneath the canopy is likely to be affected and warrants further investigation. In many cases, soil DTPA-extractable Zn concentrations were at deficient levels, thus hampering its correlation to sorghum grain Zn concentration and potentially limiting the expression of genetic Zn biofortification. Knowledge of soil DTPA-extractable Zn concentrations or basic soil properties such as pH, organic carbon, and soil parent material may aid in the location of suitable available Zn fields and overall biofortification efforts. Grain Fe concentration was not significantly related to Curvularia lunata percent recovery or grain mold rating, but instead showed a relatively high variance by panicle, digestion batch, and grain subsample. Additional work is needed to address these sources of Fe variation so as to determine better if mold affects grain Fe concentrations

Monitoring projecten Bewegende stad:nodigt de vernieuwde inrichting uit tot meer bewegen?

‘De stad als sportschool’ illustreert dat de gemeente Groningen stadjers uitnodigt om te sporten en bewegen in de openbare ruimte van Groningen. Van hardlopen in het Noorderplantsoen, skeeleren in het Stadspark tot crossfit trainingen op de Grote Markt, steeds meer mensen sporten in de openbare ruimte. De nota de ‘Bewegende Stad’ moet Groningen de komende jaren sport- en beweegvriendelijker maken, Groningen zet in op het zichtbaarder en bereikbaarder maken van sportvoorzieningen, waarbij sport en spel een groter onderdeel uitmaken van de openbare ruimte. In het kader van de ‘Bewegende Stad’ zijn er van januari 2015- mei 2016 drie concrete projecten gerealiseerd: a) Outdoor Fitness Reitdiep (outdoor fitness apparaten), b) Hunze- van Starkenborgh (sport- en speelvoorzieningen) en c) Oosterkade (multifunctionele sport- en speelplek). In dit onderzoek staat de monitoring van deze projecten centraal en wordt bekeken in hoeverre de vernieuwde inrichting van de openbare ruimte uitnodigt tot meer bewegen, sporten en spelen. Hierbij zal er gekeken worden in welke mate de voorzieningen worden gebruikt, wie de gebruikers zijn en in welke mate de gebruikers tevreden zijn over de vernieuwde voorzieningen