987 research outputs found

    Efficient Partnership Dissolution under Buy/Sell Clauses

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    When a partnership comes to an end partners have to determine the terms of the dissolution. A well known way to do so is by enforcing a buy/sell option. Under its rules one partner has to offer a price for the partnership and the other agent can choose whether she wants to sell her share or buy her partner's share at this price. It is well known that in a model with private valuations this dissolution rule may generate inefficient allocations. However, we here show that if partners negotiate for the advantage of being chooser, then this buy/ sell provision results in an ex-post efficient outcome. This result helps to explain why such provisions are so widely introduced in partnership contractsmechanism design, partnerships

    Preserving Liveness Guarantees from Synchronous Communication to Asynchronous Unstructured Low-Level Languages

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    In the implementation of abstract synchronous communication in asynchronous unstructured low-level languages, e.g. using shared variables, the preservation of safety and especially liveness properties is a hitherto open problem due to inherently different abstraction levels. Our approach to overcome this problem is threefold: First, we present our notion of handshake refinement with which we formally prove the correctness of the implementation relation of a handshake protocol. Second, we verify the soundness of our handshake refinement, i.e., all safety and liveness properties are preserved to the lower level. Third, we apply our handshake refinement to show the correctness of all implementations that realize the abstract synchronous communication with the handshake protocol. To this end, we employ an exemplary language with asynchronous shared variable communication. Our approach is scalable and closes the verification gap between different abstraction levels of communication

    On the Unification of Process Semantics: Logical Semantics

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    We continue with the task of obtaining a unifying view of process semantics by considering in this case the logical characterization of the semantics. We start by considering the classic linear time-branching time spectrum developed by R.J. van Glabbeek. He provided a logical characterization of most of the semantics in his spectrum but, without following a unique pattern. In this paper, we present a uniform logical characterization of all the semantics in the enlarged spectrum. The common structure of the formulas that constitute all the corresponding logics gives us a much clearer picture of the spectrum, clarifying the relations between the different semantics, and allows us to develop generic proofs of some general properties of the semantics.Comment: In Proceedings SOS 2011, arXiv:1108.279

    Modelling landscape management scenarios for equitable and sustainable futures in rural areas based on ecosystem services

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    Scenario analysis is a useful technique to inform landscape planning of social-ecological systems by modelling future trends in ecosystem service supply and distribution. This is especially critical in floodplain agroecosystems of rural areas, which are at risk of losing riparian forest corridors due to increasing land use conversion for agricultural production and other ecosystem services due to rural abandonment. However, few studies investigating the effects of land management combine social and ecological modelling in scenario analyses. We estimated the supply of 16 ecosystem services under five alternative scenarios along two gradients: agricultural intensification of the floodplain and active ecological restoration of the riparian forest. We used redundancy analyses to detect ecosystem service bundles and interviews to identify societal gains and losses associated with each management scenario. Our results show how land management influences both the supply and distribution of ecosystem services. Scenarios promoting active ecological restoration supplied more services and benefited a larger range of societal sectors than scenarios focused on provisioning services. We also found two consistent bundles across scenarios, one related to less intensive food supply and another one related to outdoor activities. Interestingly, additional services were included in these bundles in the different scenarios, reflecting land management effects. Landscape scale management promoting both the conservation of ecosystem functioning and the sustainable use of provisioning services could supply a more balanced set of ecosystem services and benefit a larger number of societal sectors, contributing to more equitable and sustainable futures in rural areas

    Oral pathology in the Iberian Neanderthals

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    In 1994, a series of human bones was found at the Sidrón cave in Borines (Concejo de Piloña, Asturias), Spain. Since the investigators suspected that they were dealing with human remains from the Spanish Civil War (1936-1939), the bones were collected by the Civil Guard, but were not subjected to archeological scrutiny. The finding was reported then to the corresponding authorities, who had them sent to the Laboratory of Forensic Anthropology of the Forensic Institute of Madrid (Spain), where an anthropological study was undertaken. This revealed the extraordinary palaeoanthropological and palaeopathological interest of the remains. The specimen studied herein, a mandible catalogued as SDR 7-8 (SIDRON 7-8) by the Forensic Laboratory in Madrid (Spain) and belonging to Homo neanderthalensis, with an age of 90,000 to 40,000 years BCE, showed special characteristics of oral pathology, making it a specimen of great palaeodontological interest.Key words: Mandible, Neanderthal, oral pathology, Sidrón, Asturias

    Los genes del desarrollo embrionario en distintas patologías: la necesidad de un abordaje pluridisciplinar.

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    Comparison of UV irradiances from Aura/Ozone Monitoring Instrument (OMI) with Brewer measurements at El Arenosillo (Spain) – Part 2: Analysis of site aerosol influence

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    Several validation studies have shown a notable overestimation of the clear sky ultraviolet (UV) irradiance at the Earth's surface derived from satellite sensors such as the Total Ozone Mapping Spectrometer (TOMS) and the Ozone Monitoring Instrument (OMI) with respect to ground-based UV data at many locations. Most of this positive bias is attributed to boundary layer aerosol absorption that is not accounted for in the TOMS/OMI operational UV algorithm. Therefore, the main objective of this study is to analyse the aerosol effect on the bias between OMI erythemal UV irradiance (UVER) and spectral UV (305 nm, 310 nm and 324 nm) surface irradiances and ground-based Brewer spectroradiometer measurements from October 2004 to December 2008 at El Arenosillo station (37.1° N, 6.7° W, 20 m a.s.l.), with meteorological conditions representative of the South-West of Spain. <br><br> The effects of other factors as clouds, ozone and the solar elevation over this intercomparison were analysed in detail in a companion paper (Antón et al., 2010). In that paper the aerosol effects were studied making only a rough evaluation based on aerosol optical depth (AOD) information at 440 nm wavelength (visible range) without applying any correction. We have used the precise information given by single scattering albedo (SSA) from AERONET for the determination of absorbing aerosols which has allowed the correction of the OMI UV data. <br><br> An aerosol correction expression was applied to the OMI operational UV data using two approaches to estimate the UV absorption aerosol optical depth, AAOD. The first approach was based on an assumption of constant SSA value of 0.91. This approach reduces the OMI UVER bias against the reference Brewer data from 13.4% to 8.4%. Second approach uses daily AERONET SSA values reducing the bias only to 11.6%. Therefore we have obtained a 37% and 12% of improvement respectively. For the spectral irradiance at 324 nm, the OMI bias is reduced from 10.5% to 6.98% for constant SSA and to 9.03% for variable SSA. Similar results were obtained for spectral irradiances at 305 nm, and 310 nm. <br><br> Contrary to what was expected, the constant SSA approach has a greater bias reduction than variable SSA, but this is a reasonable result according to the discussion about the reliability of SSA values. Our results reflect the level of accuracy that may be reached at the present time in this type of comparison, which may be considered as satisfactory taking into account the remaining dependence on other factors. Nevertheless, improvements must be accomplished to determine reliable absorbing aerosol properties, which appear as a limiting factor for improving OMI retrievals
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