9,836 research outputs found
Temporalized logics and automata for time granularity
Suitable extensions of the monadic second-order theory of k successors have
been proposed in the literature to capture the notion of time granularity. In
this paper, we provide the monadic second-order theories of downward unbounded
layered structures, which are infinitely refinable structures consisting of a
coarsest domain and an infinite number of finer and finer domains, and of
upward unbounded layered structures, which consist of a finest domain and an
infinite number of coarser and coarser domains, with expressively complete and
elementarily decidable temporal logic counterparts.
We obtain such a result in two steps. First, we define a new class of
combined automata, called temporalized automata, which can be proved to be the
automata-theoretic counterpart of temporalized logics, and show that relevant
properties, such as closure under Boolean operations, decidability, and
expressive equivalence with respect to temporal logics, transfer from component
automata to temporalized ones. Then, we exploit the correspondence between
temporalized logics and automata to reduce the task of finding the temporal
logic counterparts of the given theories of time granularity to the easier one
of finding temporalized automata counterparts of them.Comment: Journal: Theory and Practice of Logic Programming Journal Acronym:
TPLP Category: Paper for Special Issue (Verification and Computational Logic)
Submitted: 18 March 2002, revised: 14 Januari 2003, accepted: 5 September
200
Investigation of dominant hydrological processes in a tropical catchment in a monsoonal climate via the downward approach
International audienceThis study explores the dominant processes that may be responsible for the observed streamflow response in Seventeen Mile Creek, a tropical catchment located in a monsoonal climate in Northern Territory, Australia. The hydrology of this vast region of Australia is little understood due to the low level of information and gauging that is available. Any insights that can be gained from the few well gauged catchments that exist can be valuable for predictions and water resource assessments in other poorly gauged or ungauged catchments in the region. To this end, the available rainfall and runoff data from Seventeen Mile Creek catchment are analyzed through the systematic and progressive development and testing of rainfall-runoff models of increasing complexity, by following the "downward" or "top-down" approach. At the end a multiple bucket model (4 buckets in parallel) is developed. Modelling results suggest that the catchment's soils and the landscape in general have a high storage capacity, generating a significant fraction of delayed runoff, whereas saturation excess overland flow occurs only after heavy rainfall events. The sensitivity analyses carried out with the model with regard to soil depth and temporal rainfall variability reveal that total runoff from the catchment is more sensitive to rainfall variations than to soil depth variations, whereas the partitioning into individual components of runoff appears to be more influenced by soil depth variations. The catchment exhibits considerable inter-annual variability in runoff volumes and the greatest determinant of this variability turns out to be the seasonality of the climate, the timing of the wet season, and temporal patterns of the rainfall. The water balance is also affected by the underlying geology, nature of the soils and the landforms, and the type, density and dynamics of vegetation, although, information pertaining to these is lacking
Euthanasia and physician-assisted suicide for patients with depression. Thought-provoking remarks
Euthanasia and medical assistance in dying entail daunting ethical and moral challenges, in addition to a host of medical and clinical issues, which are further complicated in cases of patients whose decision-making skills have been negatively affected or even impaired by psychiatric disorders. The authors closely focus on clinical depression and relevant European laws that have over the years set firm standards in such a complex field. Pertaining to the mental health realm specifically, patients are required to undergo a mental competence assessment in order to request aid in dying. The way psychiatrists deal and interact with decisionally capable patients who have decided to end their own lives, on account of sufferings which they find to be unbearable, may be influenced by subjective elements such as ethical and cultural biases on the part of the doctors involved. Moreover, critics of medical aid in dying claim that acceptance of such practices might gradually lead to the acceptance or practice of involuntary euthanasia for those deemed to be nothing more than a burden to society, a concept currently unacceptable to the vast majority of observers. Ultimately, the authors conclude, the key role of clinicians should be to provide alternatives to those who feel so hopeless as to request assistance in dying, through palliative care and effective social and health care policies for the weakest among patients: lonely, depressed or ill-advised people
Constraint optimization and landscapes
We describe an effective landscape introduced in [1] for the analysis of
Constraint Satisfaction problems, such as Sphere Packing, K-SAT and Graph
Coloring. This geometric construction reexpresses these problems in the more
familiar terms of optimization in rugged energy landscapes. In particular, it
allows one to understand the puzzling fact that unsophisticated programs are
successful well beyond what was considered to be the `hard' transition, and
suggests an algorithm defining a new, higher, easy-hard frontier.Comment: Contribution to STATPHYS2
Investigation of dominant hydrological processes in a tropical catchment in a monsoonal climate via the downward approach
This study explores the dominant processes that may be responsible for the observed streamflow response in Seventeen Mile Creek, a tropical catchment located in a monsoonal climate in Northern Territory, Australia. The hydrology of this vast region of Australia is poorly understood due to the low level of information and gauging that are available. Any insights that can be gained from the few well gauged catchments that do exist can be valuable for predictions and water resource assessments in other poorly gauged or ungauged catchments in the region. To this end, the available rainfall and runoff data from Seventeen Mile Creek catchment are analyzed through the systematic and progressive development and testing of rainfall-runoff models of increasing complexity, by following the "downward" or "top-down" approach. This procedure resulted in a multiple bucket model (4 buckets in parallel). Modelling results suggest that the catchment's soils and the landscape in general have a high storage capacity, generating a significant fraction of delayed runoff, whereas saturation excess overland flow occurs only after heavy rainfall events. The sensitivity analyses carried out with the model with regard to soil depth and temporal rainfall variability revealed that total runoff from the catchment is more sensitive to rainfall variations than to soil depth variations, whereas the partitioning into individual components of runoff appears to be more influenced by soil depth variations. The catchment exhibits considerable inter-annual variability in runoff volumes and the greatest determinant of this variability turns out to be the seasonality of the climate, the timing of the wet season, and temporal patterns of the rainfall. The water balance is also affected by the underlying geology, nature of the soils and the landforms, and the type, density and dynamics of vegetation, although information pertaining to these is lacking
Knocking on the EU's door: the political economy of EU-Ukraine relations
The EU has recently launched the European Neighbourhood Policy, aimed at fostering integration with countries located close to its borders. This article proposes a liberal intergovernmentalist framework for the analysis of Ukraine's prospects of integration with the EU and apply it to evaluate the main economic and political benefits and costs associated to three possible scenarios: free trade area, fully developed European Neighbourhood Policy and EU accession. Two main conclusions can be drawn. Firstly, gains from integration would be asymmetrically distributed and would mostly accrue to Ukraine, whilst the main obstacles to integration would not be economic, but political. Secondly, the European Neighbourhood Policy does not represent a credible long-term alternative to EU membership for Ukraine; thus the outcome of the integration process should probably consist either in the mere creation of a free trade area or in EU accession
Random subcubes as a toy model for constraint satisfaction problems
We present an exactly solvable random-subcube model inspired by the structure
of hard constraint satisfaction and optimization problems. Our model reproduces
the structure of the solution space of the random k-satisfiability and
k-coloring problems, and undergoes the same phase transitions as these
problems. The comparison becomes quantitative in the large-k limit. Distance
properties, as well the x-satisfiability threshold, are studied. The model is
also generalized to define a continuous energy landscape useful for studying
several aspects of glassy dynamics.Comment: 21 pages, 4 figure
Ethical and medico-legal remarks on uterus transplantation: may it solve uterine factor infertility?
Uterus transplantation was firstly tested with animal trials sixty-five years ago. Despite several successful attempts in human subjects, the different procedures still lay at the experimental stage, in need of further studies and investigations before they can be considered as standard clinical practices. Uterus transplant cannot be regarded as a life-saving procedure, but rather a method to restore woman ability to procreate, when lost, thus improving her quality of life. Uterus transplant is a complex surgical procedure and presents significant health threats. Medical staff should therefore always obtain informed consent from patients, emphasizing such risks. Before that, women undergoing uterine transplants should be thoroughly informed about the hazards inherent to the procedure and especially about the dangers of immunosuppressant drugs, administered after the surgery which may injure the fetus, eventually formed in the restored organ and even lead to its death, thus nullifying the purpose of the transplant itself. Therefore, the risk-benefit ratio of uterus transplantation needs to be carefully assessed and described
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