987 research outputs found
Efficient Partnership Dissolution under Buy/Sell Clauses
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
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
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
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
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
Comparison of UV irradiances from Aura/Ozone Monitoring Instrument (OMI) with Brewer measurements at El Arenosillo (Spain) – Part 2: Analysis of site aerosol influence
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.
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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.
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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.
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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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