Traffic forecasts under uncertainty and capacity constraints

Traffic forecasts provide essential input for the appraisal of transport investment projects. However, according to recent empirical evidence, long-term predictions are subject to high levels of uncertainty. This paper quantifies uncertainty in traffic forecasts for the tolled motorway network in Spain. Uncertainty is quantified in the form of a confidence interval for the traffic forecast that includes both model uncertainty and input uncertainty. We apply a stochastic simulation process based on bootstrapping techniques. Furthermore, the paper proposes a new methodology to account for capacity constraints in long-term traffic forecasts. Specifically, we suggest a dynamic model in which the speed of adjustment is related to the ratio between the actual traffic flow and the maximum capacity of the motorway. This methodology is applied to a specific public policy that consists of suppressing the toll on a certain motorway section before the concession expires.

The Role of supply constraints in multiplier analysis

Multiplier analysis based upon the information contained in Leontief's inverse is undoubtedly part of the core of the input-output methodology and numerous applications an extensions have been developed that exploit its informational content. Nonetheless there are some implicit theoretical assumptions whose implications have perhaps not been fully assessed. This is the case of the 'excess capacity' assumption. Because of this assumption resources are available as needed to adjust production to new equilibrium states. In real world applications, however, new resources are scarce and costly. Supply constraints kick in and hence resource allocation needs to take them into account to really assess the effect of government policies. Using a closed general equilibrium model that incorporates supply constraints, we perform some simple numerical exercises and proceed to derive a 'constrained' multiplier matrix that can be compared with the standard 'unrestricted' multiplier matrix. Results show that the effectiveness of expenditure policies hinges critically on whether or not supply constraints are considered.

Implementation of IPM programs on European greenhouse tomato production areas: Tools and constraints

Whiteflies and whitefly-transmitted viruses are some of the major constraints on European tomato production. The main objectives of this study were to: identify where and why whiteflies are a major limitation on tomato crops; collect information about whiteflies and associated viruses; determine the available management tools; and identify key knowledge gaps and research priorities. This study was conducted within the framework of ENDURE (European Network for Durable Exploitation of Crop Protection Strategies). Two whitefly species are the main pests of tomato in Europe: Bemisia tabaci and Trialeurodes vaporariorum. Trialeurodes vaporariorum is widespread to all areas where greenhouse industry is present, and B. tabaci has invaded, since the early 1990’s, all the subtropical and tropical areas. Biotypes B and Q of B. tabaci are widespread and especially problematic. Other key tomato pests are Aculops lycopersici, Helicoverpa armigera, Frankliniella occidentalis, and leaf miners. Tomato crops are particularly susceptible to viruses causingTomato yellow leaf curl disease (TYLCD). High incidences of this disease are associated to high pressure of its vector, B. tabaci. The ranked importance of B. tabaci established in this study correlates with the levels of insecticide use, showing B. tabaci as one of the principal drivers behind chemical control. Confirmed cases of resistance to almost all insecticides have been reported. Integrated Pest Management based on biological control (IPM-BC) is applied in all the surveyed regions and identified as the strategy using fewer insecticides. Other IPM components include greenhouse netting and TYLCD-tolerant tomato cultivars. Sampling techniques differ between regions, where decisions are generally based upon whitefly densities and do not relate to control strategies or growing cycles. For population monitoring and control, whitefly species are always identified. In Europe IPM-BC is the recommended strategy for a sustainable tomato production. The IPM-BC approach is mainly based on inoculative releases of the parasitoids Eretmocerus mundus and Encarsia formosa and/or the polyphagous predators Macrolophus caliginosus and Nesidiocoris tenuis. However, some limitations for a wider implementation have been identified: lack of biological solutions for some pests, costs of beneficials, low farmer confidence, costs of technical advice, and low pest injury thresholds. Research priorities to promote and improve IPM-BC are proposed on the following domains: (i) emergence and invasion of new whitefly-transmitted viruses; (ii) relevance of B. tabaci biotypes regarding insecticide resistance; (iii) biochemistry and genetics of plant resistance; (iv) economic thresholds and sampling techniques of whiteflies for decision making; and (v) conservation and management of native whitefly natural enemies and improvement of biological control of other tomato pests.

Opportunities and constraints in schistosomiasis vaccine development: infection characteristics and industry realities

The notes provided in this article relate to two components of the development of vaccines against schistosomiasis: (1) The characteristics of schistosome infections (eg. features of the schistosome life cycle), and the parasite itself, that have implications for vaccination strategies; (2) The characteristics of the biopharmaceutical industry that have implications for product development. As will be seen, these two topic areas are not vastly disparate.

When nightclub security agents assault clients.

In 2006, a medico-legal consultation service devoted to adult victims of interpersonal violence was set up at the Lausanne University Hospital Centre, Switzerland: the Violence Medical Unit. Most patients are referred to the consultation by the Emergency Department. They are received by forensic nurses for support, forensic examination (in order to establish medical report) and community orientation. Between 2007 and 2009, among community violence, aggressions by security agents of nightclubs on clients have increased from 6% to 10%. Most of the victims are young men who had drunk alcohol before the assault. 25.7% presented one or several fractures, all of them in the head area. These findings raise questions about the ability of security agents of nightclubs to deal adequately with obviously risky situations and ensure client security.

A critical application of securitization theory: overcoming the normative dilemma of writing security

This article addresses the normative dilemma located within the application of `securitization,’ as a method of understanding the social construction of threats and security policies. Securitization as a theoretical and practical undertaking is being increasingly used by scholars and practitioners. This scholarly endeavour wishes to provide those wishing to engage with securitization with an alternative application of this theory; one which is sensitive to and self-reflective of the possible normative consequences of its employment. This article argues that discussing and analyzing securitization processes have normative implications, which is understood here to be the negative securitization of a referent. The negative securitization of a referent is asserted to be carried out through the unchallenged analysis of securitization processes which have emerged through relations of exclusion and power. It then offers a critical understanding and application of securitization studies as a way of overcoming the identified normative dilemma. First, it examines how the Copenhagen School’s formation of securitization theory gives rise to a normative dilemma, which is situated in the performative and symbolic power of security as a political invocation and theoretical concept. Second, it evaluates previous attempts to overcome the normative dilemma of securitization studies, outlining the obstacles that each individual proposal faces. Third, this article argues that the normative dilemma of applying securitization can be avoided by firstly, deconstructing the institutional power of security actors and dominant security subjectivities and secondly, by addressing countering or alternative approaches to security and incorporating different security subjectivities. Examples of the securitization of international terrorism and immigration are prominent throughout.

Conflict, Peace and Security in Africa: an Assessment and New Questions After 50 Years of African Independence

Since the independence processes in the African continent, armed conflicts, peace and security have raised concern and attention both at the domestic level and at the international scale. In recent years, all aspects have undergone significant changes which have given rise to intense debate. The end of some historical conflicts has taken place in a context of slight decrease in the number of armed conflicts and the consolidation of post-conflict reconstruction processes. Moreover, African regional organizations have staged an increasingly more active internal shift in matters related to peace and security, encouraged by the idea of promoting “African solutions to African problems”. This new scenario, has been accompanied by new uncertainties at the security level and major challenges at the operational level, especially for the African Union. This article aims to ascertain the state of affairs on all these issues and raise some key questions to consider.

The Security Council and the Legitimacy of the Use of Force: Legal, Normative, and Social Aspects.

Tal i com estableix la Carta de les Nacions Unides, el Consell de Seguretat determina l’existència d’una amenaça a la pau, un trencament de la pau o un acte d’agressió i decideix les mesures que han de fer-se servir per restaurar la pau i seguretat internacionals, també l’ús de la força. L’objectiu d’aquest article és explorar la legitimitat d’aquest ús de la força. Amb aquest objectiu, el text parteix d’una definició centrada en les seves dimensions legal, normativa i social. En segon lloc, s’analitzarà com aquestes dimensions estan representades als debats del Consell de Seguretat de la guerra d’Irak de 2003, un dels usos de la força més controvertits i que més debat ha generat als darrers anys. Finalment, l’anàlisi proposat permet treure algunes conclusions sobre les bases canviants de la legitimitat de l’ús de la força.

A stable and 40Ar/39Ar isotope study of a major thrust in the Helvetic nappes (Swiss Alps) - Evidence for fluid-flow and constraints on nappe kinematics

Stable isotope and Ar-40/Ar-39 measurements,were made on samples associated with a major tectonic discontinuity in the Helvetic Alps, the basal thrust of the Diablerets nappe (external zone of the Alpine Belt) in order to determine both the importance of fluids in this thrust zone and the timing of thrusting. A systematic decrease in the delta(18)O values (up to 6 parts per thousand) of calcite, quartz, and white mica exists within a 10- to 70-m-wide zone over a distance of 37 km along the thrust, and they become more pronounced toward the root of the nappe. A similar decrease in the delta(13)C values of calcite is observed only in the deepest sections (up to 3 parts per thousand). The delta D-SMOW (SMOW = standard mean ocean water) values of white mica are -54 parts per thousand +/- 8 parts per thousand (n = 22) and are independent of the distance from the thrust. These variations are interpreted to reflect syntectonic solution reprecipitation during fluid passage along the thrust. The calculated delta(18)O and delta D values (versus SMOW) for the fluid in equilibrium with the analyzed minerals is 12 parts per thousand to 16 parts per thousand and -30 parts per thousand to +5 parts per thousand, respectively, for assumed temperatures of 250 to 450 degrees C. The isotopic and structural data are consistent with fluids derived from the deep-seated roots of the Helvetic nappes where large volumes of Mesozoic sediments were metamorphosed to the amphibolite facies, It is suggested that connate and metamorphic waters, overpressured by rapid tectonic burial in a subductive system escaped by upward infiltration along moderately dipping pathways until they reached the main shear zone at the base of the moving pile, where they were channeled toward the surface, This model also explains the mechanism by which large amounts of fluid were removed from the Mesozoic sediments during Alpine metamorphism. White mica Ar-49/Ar-39 ages vary from 27 Ma far from the Diablerets thrust to 15 Ma along the thrust. An older component is observed in micas far from the thrust, interpreted as a detrital signature, and indicates that regional metamorphic temperatures were less than about 350 degrees C. The;plateau and near plateau ages nearest the thrust are consistent with either neocrystallization of white mica or argon loss by recrystallization during thrusting, which may have been enhanced in the zones of highest fluid flow. The 15 Ma Ar-40/Ar-39 age plateau measured on white mica sampled exactly on the thrust surface dates the end of both fluid flow and tectonic transport.

Compositional Constraints in the Extremely GC-poor Genome of Plasmodium falciparum

We have analyzed the compositional properties of coding (protein encoding) and non-coding sequences of Plasmodium falciparum, a unicellular parasite characterized by an extremely AT-rich genome. GC% levels, base and dinucleotide frequencies were studied. We found that among the various factors that contribute to the properties of the sequences analyzed, the most relevant are the compositional constraints which operate on the whole genome

Publicizing insecurity, privatizing security: Chinese wholesalers' surveillance cameras in a Paris suburb

Since the early nineties, several hundreds of Chinese immigrants have settled in what has become known as the 'Chinese wholesalers area'. For the past two years, Chinese wholesalers in Aubervilliers have been calling on public authorities to address the problem of street robberies and violent thefts, which they experience on a daily basis. Yet, they have been encouraged by the authorities to ensure their own protection, by - amongst other things - installing surveillance cameras to film the streets. This is illegal according to French legislation on camera surveillance. Knowing this, why have surveillance cameras been adopted as a solution? This question guides the ethnographic analysis presented here of a situation where the installation of surveillance cameras was locally negotiated by the main actors involved - namely, the wholesalers' representatives and the police.

Liquid line of descent of a basanitic liquid at 1.5 GPa: Constraints for metasomatic vein formation

The metasomatism observed in the oceanic and continental lithosphere is generally interpreted to represent a continuous differentiation process forming anhydrous and hydrous veins plus a cryptic enrichment in the surrounding peridotite. In order to constrain the mechanisms of vein formation and potentially clarify the nature and origin of the initial metasomatic agent, we performed a series of high-pressure experiments simulating the liquid line of descent of a basanitic magma differentiating within continental or mature oceanic lithosphere. This series of experiments has been conducted in an end-loaded piston cylinder apparatus starting from an initial hydrous ne-normative basanite at 1.5 GPa and temperature varying between 1,250 and 980°C. Near-pure fractional crystallization process was achieved in a stepwise manner in 30°C temperature steps and starting compositions corresponding to the liquid composition of the previous, higher-temperature glass composition. Liquids evolve progressively from basanite to peralkaline, aluminum-rich compositions without significant SiO2 variation. The resulting cumulates are characterized by an anhydrous clinopyroxene + olivine assemblage at high temperature (1,250-1,160°C), while at lower temperature (1,130-980°C), hydrous cumulates with dominantly amphibole + minor clinopyroxene, spinel, ilmenite, titanomagnetite and apatite (1,130-980°C) are formed. This new data set supports the interpretation that anhydrous and hydrous metasomatic veins could be produced during continuous differentiation processes of primary, hydrous alkaline magmas at high pressure. However, the comparison between the cumulates generated by the fractional crystallization from an initial ne-normative liquid or from hy-normative initial compositions (hawaiite or picrobasalt) indicates that for all hydrous liquids, the different phases formed upon differentiation are mostly similar even though the proportions of hydrous versus anhydrous minerals could vary significantly. This suggests that the formation of amphibole-bearing metasomatic veins observed in the lithospheric mantle could be linked to the differentiation of initial liquids ranging from ne-normative to hy-normative in composition. The present study does not resolve the question whether the metasomatism observed in lithospheric mantle is a precursor or a consequence of alkaline magmatism; however, it confirms that the percolation and differentiation of a liquid produced by a low degree of partial melting of a source similar or slightly more enriched than depleted MORB mantle could generate hydrous metasomatic veins interpreted as a potential source for alkaline magmatism by various authors.