1,762 research outputs found

    Report No. 31: The Role of Social Protection as an Economic Stabiliser: Lessons from the Current Crisis

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    Report based on a study conducted for the European Parliament, Bonn 2010 (188 pages)

    A comparative study of different fatigue failure assessments of welded bridge details

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    Five different welded joints frequently used in steel bridges have been selected to investigate the accuracy and applicability of three fatigue assessment methods. The first method, also categorised as the global method, is the nominal stress method, while the more advanced methods are the hot spot and the effective notch stress methods. Solid element based finite element models for welded bridge details were created by following the modelling requirements of each fatigue assessment method. A statistical evaluation based on the results of the finite element analyses and the fatigue test data collected from the literature was performed to determine the mean and characteristic fatigue strength. In addition, the standard deviation for each data series was also determined to conclude how well each method describes the fatigue strength of each welded detail. A method with a lower standard deviation is regarded as more accurate. Moreover, the evaluated results from each method were compared with the recommended fatigue strength values in the Eurocode 3 (EN 1993-1-9:2005) and IIW codes. In the light of the test results in this study, it appears that the codes are in reasonable agreement with the test data, even though a few examples of the opposite occurred. The conclusion based on the revised results in this article indicates that the nominal stress method yields satisfactory results, despite its simplicity. When considering the effort involved in creating FE models for numerical analysis, it seems clear that the choice of the nominal method is fairly acceptable

    Alqueva. Changing Ecologies of the Montado Landscape. Alentejo, Portugal

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    In the past decade Alqueva Dam brought a tremendous landscape change in all three sectors-environmental, social and economic. While the dam and reservoir was a project which was carefully executed, there are certain issues which need to be monitored/rectified as the reservoir goes into 5th straight year with full capacity. The Alentejo region is currently under threats from environmental stress (drought, climate change and habitat disturbances), social stress (with declining population in nearby villages) and is also struggling to attract people to this economically backward region in Portugal. This report presents analysis and recommendations proposed by Environmental Planning Students from UC Berkeley to create and revise holistic strategies that measure the effects of the dam and future proposals to improve human access and ecological values of Alentejo region.Portuguese Studies Program, UCBerkeley ; EDI

    Elaboration d'une structure de collecte des déchets organiques à l'aide de la théorie constructale

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    International audienceLa gestion des déchets présente des enjeux économiques et environnementaux majeurs pour nos sociétés, et notamment sur la question des transports. Ceux-ci peuvent ainsi représenter jusqu'à 70% des coûts financiers d'un système de gestion (Uson et al., 2013). Des études ont de plus montré que les systèmes en réseau possèdent une plus grande flexibilité face à la variabilité temporelle des flux de déchets (Rojo, 2009). La difficulté réside donc dans l'optimisation de la configuration spatiale de ces réseaux sur le territoire. La démarche proposée s'appuie sur la loi constructale, énonçant que les réseaux naturels (bronches pulmonaires, bassins versants) dotés d'un degré de liberté jugé suffisant, adoptent une forme qui minimise la résistance des flux qui les traversent (Bejan et Lorente, 2009). La loi constructale a été appliquée au cas de la collecte de déchets des particuliers vers un site de transbordement. Deux types de collecte ont été comparés: une collecte conventionnelle, avec une capacité des camions fixée, et une collecte "constructale", caractérisée par l'intervention en série de deux types de véhicules, de capacités différentes (degré de liberté). L'analyse a été réalisée sur le critère financier associé au transport des déchets. Les résultats ont montré que la collecte constructale devient, d'un point de vue opérationnel, économiquement plus performante qu'une collecte conventionnell

    Optimal approach for the interaction between dsos and aggregators to activate der flexibility in the distribution grid

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    Proceedings of: CIRED 2017: The 24th International Conference and Exhibition on Electricity Distribution. 12-15 June 2017. Glasgow (REINO UNIDO)The process of predicting the behaviours of distributed energy resources (DER) and controlling them is complex. It will require a huge effort from the distribution system operator (DSO) to establish communication channels to all available DERs in the network and to integrate new ones into the automation system. It is therefore important that a third party (the Aggregator) takes care of the communication with DERs in the network. This study will focus on the following: DSO functionalities that enable communication between the flexibility market and the aggregator; the aggregator role and the functionalities required to be a successful business entity; and the approach (DSO/aggregator model) that was identified and adopted by the IDE4L project. The study concludes and recommends the approach that was adopted by the IDE4L project as the most efficient one to solve congestion and to ensure harmony in the sequence of events. Based on the achieved results, we believe that the IDE4L approach is the optimal method of communication that ensures efficiency, effectiveness, and harmony in communication among the DSO and all other flexibility market players

    The binary properties of the pulsating subdwarf B eclipsing binary PG 1336-018 (NY Virginis)

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    Aims. We present an unbiased orbit solution and mass determination of the components of the eclipsing binary PG1336−018 as a critical test for the formation scenarios of subdwarf B stars. Methods. We obtained high-resolution time series VLT/UVES spectra and high-speed multicolour VLT/ULTRACAM photometric observations of PG1336−018, a rapidly pulsating subdwarf B star in a short period eclipsing binary. Results. Combining the radial velocity curve obtained from the VLT/UVES spectra with the VLT/ULTRACAM multicolour lightcurves, we determined numerical orbital solutions for this eclipsing binary. Due to the large number of free parameters and their strong correlations, no unique solution could be found, only families of solutions. We present three solutions of equal statistical significance, two of which are compatible with the primary having gone through a core He-flash and a common-envelope phase described by the α-formalism. These two models have an sdB primary of 0.466 M and 0.389 M, respectively. Finally, we report the detection of the Rossiter-McLaughlin effect for PG1336−018

    Neurovisceral phenotypes in the expression of psychiatric symptoms

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    This review explores the proposal that vulnerability to psychological symptoms, particularly anxiety, originates in constitutional differences in the control of bodily state, exemplified by a set of conditions that include Joint Hypermobility, Postural Tachycardia Syndrome and Vasovagal Syncope. Research is revealing how brainbody mechanisms underlie individual differences in psychophysiological reactivity that can be important for predicting, stratifying and treating individuals with anxiety disorders and related conditions. One common constitutional difference is Joint Hypermobility, in which there is an increased range of joint movement as a result of a variant of collagen. Joint hypermobility is over-represented in people with anxiety, mood and neurodevelopmental disorders. It is also linked to stress-sensitive medical conditions such as irritable bowel syndrome, chronic fatigue syndrome and fibromyalgia. Structural differences in 'emotional' brain regions are reported in hypermobile individuals, and many people with joint hypermobility manifest autonomic abnormalities, typically Postural Tachycardia Syndrome. Enhanced heart rate reactivity during postural change and as recently recognised factors causing vasodilatation (as noted post prandially, post exertion and with heat) is characteristic of Postural Tachycardia Syndrome, and there is a phenomenological overlap with anxiety disorders, which may be partially accounted for by exaggerated neural reactivity within ventromedial prefrontal cortex. People who experience Vasovagal Syncope, a heritable tendency to fainting induced by emotional challenges (and needle/blood phobia), are also more vulnerable to anxiety disorders. Neuroimaging implicates brainstem differences in vulnerability to faints, yet the structural integrity of the caudate nucleus appears important for the control of fainting frequency in relation to parasympathetic tone and anxiety. Together there is clinical and neuroanatomical evidence to show that common constitutional differences affecting autonomic responsivity are linked to psychiatric symptoms, notably anxiety

    The effect of fluoride on enamel and dentin formation in the uremic rat incisor

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    Renal impairment in children is associated with tooth defects that include enamel pitting and hypoplasia. However, the specific effects of uremia on tooth formation are not known. In this study, we used rat mandibular incisors, which continuously erupt and contain all stages of tooth formation, to characterize the effects of uremia on tooth formation. We also tested the hypothesis that uremia aggravates the fluoride (F)-induced changes in developing teeth. Rats were subjected to a two-stage 5/6 nephrectomy or sham operation and then exposed to 0 (control) or 50 ppm NaF in drinking water for 14 days. The effects of these treatments on food intake, body growth rate, and biochemical serum parameters for renal function and calcium metabolism were monitored. Nephrectomy reduced food intake and weight gain. Intake of F by nephrectomized rats increased plasma F levels twofold and further decreased food intake and body weight gain. Uremia affected formation of dentin and enamel and was more extensive than the effect of F alone. Uremia also significantly increased predentin width and induced deposition of large amounts of osteodentin-like matrix-containing cells in the pulp chamber. In enamel formation, the cells most sensitive to uremia were the transitional-stage ameloblasts. These data demonstrate that intake of F by rats with reduced renal function impairs F clearance from the plasma and aggravates the already negative effects of uremia on incisor tooth development

    Barley yield formation under abiotic stress depends on the interplay between flowering time genes and environmental cues

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    Abstract Since the dawn of agriculture, crop yield has always been impaired through abiotic stresses. In a field trial across five locations worldwide, we tested three abiotic stresses, nitrogen deficiency, drought and salinity, using HEB-YIELD, a selected subset of the wild barley nested association mapping population HEB-25. We show that barley flowering time genes Ppd-H1, Sdw1, Vrn-H1 and Vrn-H3 exert pleiotropic effects on plant development and grain yield. Under field conditions, these effects are strongly influenced by environmental cues like day length and temperature. For example, in Al-Karak, Jordan, the day length-sensitive wild barley allele of Ppd-H1 was associated with an increase of grain yield by up to 30% compared to the insensitive elite barley allele. The observed yield increase is accompanied by pleiotropic effects of Ppd-H1 resulting in shorter life cycle, extended grain filling period and increased grain size. Our study indicates that the adequate timing of plant development is crucial to maximize yield formation under harsh environmental conditions. We provide evidence that wild barley alleles, introgressed into elite barley cultivars, can be utilized to support grain yield formation. The presented knowledge may be transferred to related crop species like wheat and rice securing the rising global food demand for cereals
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