11,445 research outputs found

    Long-lasting floods buffer the thermal regime of the Pampas

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    This work was funded by grants from the National Research Council of Argentina (CONICET), the International Research Development Centre [IDRC-Canada, Project 106601-001], ANPCyT [PRH 27 [PICT 2013-2973; PICT 2014-2790], and the Inter-American Institute for Global Change Research [IAI, CRN II 2031], which is supported by the US National Science Foundation[Grant number 448 GEO-0452325]. We thank Dr. Horacio Zagarese from INTECH for the lagoon temperature dataset provided. We thank the anonymous reviewers for their careful reading of our manuscript and their many insightful comments and suggestions.Peer reviewedPostprin

    Current Concepts and Future Directions of CELSS

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    Bioregenerative life support systems for use in space were studied. Concepts of such systems include the use of higher plants and/or microalgae as sources of food, potable water and oxygen, and as sinks for carbon dioxide and metabolic wastes. Recycling of materials within the system will require processing of food organism and crew wastes using microbiological and/or physical chemical techniques. The dynamics of material flow within the system will require monitoring, control, stabilization and maintenance imposed by computers. Studies included higher plant and algal physiology, environmental responses, and control; flight experiments for testing responses of organisms to weightlessness and increased radiation levels; and development of ground based facilities for the study of recycling within a bioregenerative life support system

    Dangers and opportunities in managing temporary ponds

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    Although there is a growing awareness of the value of temporary ponds in Europe, there is still remarkably little information available to help guide their conservation and management. General principles which can be used to guide the management of temporary ponds as a whole have yet to be established. The aim of this article, therefore, is to give a broader overview of the main principles of temporary pond conservation, particularly by building on a number of general principles for managing ponds previously described by Biggs et al. (1994) and Williams et al. The authors emphasise the importance of surveys in order to get data on which to base management strategies. The main principles of temporary pond management are described, and examples of three case studies of ponds in England are given

    Employment insecurity and life satisfaction: The moderating influence of labour market policies across Europe

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    This article tests whether the link between employment insecurity and life satisfaction is moderated by the generosity of labour market policies across Europe. Employment insecurity provokes anxieties about (a) the difficulties of finding a new job and (b) alternative sources of non-work income. These components can be related to active and passive labour market policies, respectively. Generous policy support is thus expected to buffer the negative consequences of employment insecurity by lowering the perceived difficulty of finding a similar job or providing income maintenance during unemployment. Based on data for 22 countries from the 2010 European Social Survey, initial support for this hypothesis is found. Perceived employment insecurity is negatively associated with life satisfaction but the strength of the relationship is inversely related to the generosity of labour market policies. Employment insecurity, in other words, is more harmful in countries where labour market policies are less generous

    Predictive control for energy management in all/more electric vehicles with multiple energy storage units

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    The paper describes the application of Model Predictive Control (MPC) methodologies for application to electric and hybrid-electric vehicle drive-train formats incorporating multiple energy/power sources. Particular emphasis is given to the co-ordinated management of energy flow from the multiple sources to address issues of extended vehicle range and battery life-time for all-electric drive-trains, and emissions reduction and drive-train torsional oscillations, for hybrid-electric counterparts, whilst accommodating operational constraints and, ultimately, generic non-standard driving cycles

    Multi-Granular Optical Cross-Connect: Design, Analysis, and Demonstration

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    A fundamental issue in all-optical switching is to offer efficient and cost-effective transport services for a wide range of bandwidth granularities. This paper presents multi-granular optical cross-connect (MG-OXC) architectures that combine slow (ms regime) and fast (ns regime) switch elements, in order to support optical circuit switching (OCS), optical burst switching (OBS), and even optical packet switching (OPS). The MG-OXC architectures are designed to provide a cost-effective approach, while offering the flexibility and reconfigurability to deal with dynamic requirements of different applications. All proposed MG-OXC designs are analyzed and compared in terms of dimensionality, flexibility/reconfigurability, and scalability. Furthermore, node level simulations are conducted to evaluate the performance of MG-OXCs under different traffic regimes. Finally, the feasibility of the proposed architectures is demonstrated on an application-aware, multi-bit-rate (10 and 40 Gbps), end-to-end OBS testbed

    Integrated Support for Handoff Management and Context-Awareness in Heterogeneous Wireless Networks

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    The overwhelming success of mobile devices and wireless communications is stressing the need for the development of mobility-aware services. Device mobility requires services adapting their behavior to sudden context changes and being aware of handoffs, which introduce unpredictable delays and intermittent discontinuities. Heterogeneity of wireless technologies (Wi-Fi, Bluetooth, 3G) complicates the situation, since a different treatment of context-awareness and handoffs is required for each solution. This paper presents a middleware architecture designed to ease mobility-aware service development. The architecture hides technology-specific mechanisms and offers a set of facilities for context awareness and handoff management. The architecture prototype works with Bluetooth and Wi-Fi, which today represent two of the most widespread wireless technologies. In addition, the paper discusses motivations and design details in the challenging context of mobile multimedia streaming applications

    Dependability in Aggregation by Averaging

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    Aggregation is an important building block of modern distributed applications, allowing the determination of meaningful properties (e.g. network size, total storage capacity, average load, majorities, etc.) that are used to direct the execution of the system. However, the majority of the existing aggregation algorithms exhibit relevant dependability issues, when prospecting their use in real application environments. In this paper, we reveal some dependability issues of aggregation algorithms based on iterative averaging techniques, giving some directions to solve them. This class of algorithms is considered robust (when compared to common tree-based approaches), being independent from the used routing topology and providing an aggregation result at all nodes. However, their robustness is strongly challenged and their correctness often compromised, when changing the assumptions of their working environment to more realistic ones. The correctness of this class of algorithms relies on the maintenance of a fundamental invariant, commonly designated as "mass conservation". We will argue that this main invariant is often broken in practical settings, and that additional mechanisms and modifications are required to maintain it, incurring in some degradation of the algorithms performance. In particular, we discuss the behavior of three representative algorithms Push-Sum Protocol, Push-Pull Gossip protocol and Distributed Random Grouping under asynchronous and faulty (with message loss and node crashes) environments. More specifically, we propose and evaluate two new versions of the Push-Pull Gossip protocol, which solve its message interleaving problem (evidenced even in a synchronous operation mode).Comment: 14 pages. Presented in Inforum 200

    Valuation of environmental impacts of the Rural Development Program - A hedonic model with application of GIS

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    The payments within the Rural Development Programme 2007- 2013 seek to improve the environment and contribute to rural development and economic growth. These policy measures may therefore have visual effects on the rural landscape. To achieve a measure of willingness to pay for these effects, a hedonic pricing approach is applied. The prices for staying at holdings in the “Staying on farms” registry are used to quantify the valuation of these visual effects. The results of this study indicate that there is a relationship between the price of rental objects and spatial variables constructed in GIS. Riparian strips and animals at the farm are positively valued. Cultivated land, grazing and meadow lands close to the settings are negatively valued. Hence, this study indicate that there is a positive willingness to pay for payments addressing user values in a diversified landscape and a negative willingness to pay for actions leading to a more monotonous landscape, such as payments to extensive grazing systems.Hedonic Valuation, Rural landscape, Rural Development Program, GIS, Agricultural and Food Policy, Community/Rural/Urban Development, Q150, Q180, Q510,
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