An Approach to Static Performance Guarantees for Programs with Run-time Checks

Instrumenting programs for performing run-time checking of properties, such as regular shapes, is a common and useful technique that helps programmers detect incorrect program behaviors. This is specially true in dynamic languages such as Prolog. However, such run-time checks inevitably introduce run-time overhead (in execution time, memory, energy, etc.). Several approaches have been proposed for reducing such overhead, such as eliminating the checks that can statically be proved to always succeed, and/or optimizing the way in which the (remaining) checks are performed. However, there are cases in which it is not possible to remove all checks statically (e.g., open libraries which must check their interfaces, complex properties, unknown code, etc.) and in which, even after optimizations, these remaining checks still may introduce an unacceptable level of overhead. It is thus important for programmers to be able to determine the additional cost due to the run-time checks and compare it to some notion of admissible cost. The common practice used for estimating run-time checking overhead is profiling, which is not exhaustive by nature. Instead, we propose a method that uses static analysis to estimate such overhead, with the advantage that the estimations are functions parameterized by input data sizes. Unlike profiling, this approach can provide guarantees for all possible execution traces, and allows assessing how the overhead grows as the size of the input grows. Our method also extends an existing assertion verification framework to express "admissible" overheads, and statically and automatically checks whether the instrumented program conforms with such specifications. Finally, we present an experimental evaluation of our approach that suggests that our method is feasible and promising.Comment: 15 pages, 3 tables; submitted to ICLP'18, accepted as technical communicatio

A stochastic dynamic programming approach to optimize short-rotation coppice systems management scheduling: An application to eucalypt plantations under wildfire risk in Portugal

This article presents and discusses research with the aim of developing a stand-level management scheduling model for short-rotation coppice systems that may take into account the risk of wildfire. The use of the coppice regeneration method requires the definition of both the optimal harvest age in each cycle and the optimal number of coppice cycles within a full rotation. The scheduling of other forest operations such as stool thinning and fuel treatments (e.g., shrub removals) must be further addressed. In this article, a stochastic dynamic programming approach is developed to determine the policy (e.g., fuel treatment, stool thinning, coppice cycles, and rotation length) that maximizes expected net revenues. Stochastic dynamic programming stages are defined by the number of harvests, and state variables correspond to the number of years since the stand was planted. Wildfire occurrence and damage probabilities are introduced in the model to analyze the impact of the wildfire risk on the optimal stand management schedule policy. For that purpose, alternative wildfire occurrence and postfire mortality scenarios were considered at each stage. A typical Eucalyptus globulus Labill. stand in Central Portugal was used as a test case. Results suggest that the proposed approach may help integrate wildfire risk in short-rotation coppice systems management scheduling. They confirm that the maximum expected discounted revenue decreases with and is very sensitive to the discount rate and further suggest that the number of cycles within a full rotation is not sensitive to wildfire risk. Nevertheless, the expected rotation length decreases when wildfire risk is consideredinfo:eu-repo/semantics/publishedVersio

Modelling Hydrodynamic and Sedimentation Processes in Large Lowland Rivers: An Application to the Paraná River (Argentina)

In the last decade 1D, 2D and 3D numerical models have been extensively used to simulate river-floodplain hydraulics and sediment deposition processes in floodplains. Large river-floodplain ecosystems in lowland areas show characteristic reach lengths of the order of hundred of kilometers, floodplain widths of the order of tens of kilometers and river widths of the order of a few kilometers. The floodplain itself shows also a very complex geomorphology. Computationally intensive water flow and sediment transport models cannot take into account these peculiarities, and particularly the large time and space scales involved. On one hand, 1D models are not appropriated because the one-dimensional flow description is not representative of the complex flow pattern; on the other hand, higher dimensionality models, even if they can provide the necessary level of processes representation at small spatial scales, cannot be applied over large time and space scales due to the computational demands. An alternative to high resolution models is the implementation of quasi-2D models which can capture the fundamental characteristic of water flow and sediment dynamics in those situations. Thus, a compromise between computational costs and processes representation can be achieved. In this work a quasi-2D model, suitable for the time-dependent water and sediment transport processes simulation in large lowland river systems, including their floodplain, is presented. Water flow and sediment equations are represented by means of the interconnected irregular cells scheme. Different simplifications of 1D Saint Venant equations are used to represent the discharge laws between fluvial cells. Spatially-distributed transport and deposition of fine sediments throughout the river-floodplain system are simulated. The model is applied over a 208 km reach of the Paraná River between the cities of Diamante and Ramallo (Argentina) and involving a river-floodplain area of 8100 km². After calibration and validation, the model is applied to predict water and sediment dynamics during synthetically generated extraordinary floods of 100, 1000 and 10000 years return period. The potential impact of a 56 km long road embankment constructed across the entire floodplain was simulated. Results with and without the road embankment shows that upstream water levels, inundation extent, flow duration and sediment deposition increases in the presence of the embankment.National University of Rosario. Rosario, Argentina.University of Newcastle, Newcastle, Australia

Addressing wildfire risk in a landscape-level scheduling model: an application in Portugal

Fundamental Research - Forest ManagementThe paper presents and discusses research aiming at the development of a forested landscape management scheduling model that may address the risk of wildfires. A general indicator is built from wildfire occurrence and damage probabilities to assess stand-level resistance to wildfires. This indicator is developed to further address the specificity of each stand configuration (e.g., shape and size) and spatial context (neighboring stands characteristics). The usefulness of the development of such an indicator is tested within a mixed integer programming (MIP) approach to find the location and timing of management options (e.g., fuel treatment, thinning, clearcut) that may maximize the forested landscape expected net revenues. The Leiria National Forest, a Portuguese forest in central Portugal, was used as a case study. Results suggest that the proposed approach may help integrate wildfire risk in forested landscape management planning and assess its impact on the optimal plan. Results further show that prescriptions that include fuel treatments are often chosen over others that do not include them, thus highlighting the importance of wildfire management efforts. Finally, they provide interesting insights about the role of thinnings and fuel treatment in mitigating wildfire riskinfo:eu-repo/semantics/publishedVersio

Evaluation of Sentinel-1, SMAP and SMOS surface soil moisture products for distributed eco-hydrological modelling in Mediterranean forest basins

[EN] Reliable distributed hydrological modeling, especially in semi-arid areas, must consider the inclusion of surface soil moisture (SSM) spatial information during the calibration process. This variable plays a key role in the evapotranspiration processes that determine the hydrological cycle. The coarse resolution of the SSM estimates by satellite remote sensing has restricted the application of this approach to only large basins, focusing most of the studies in the consideration of simply the temporal dynamics of this variable. The growing efforts in providing higher spatial resolution through disaggregating methodologies or new sensor estimates facilitates the application of this spatial approach to small basins. This paper explores the applicability of the currently available satellite surface soil moisture estimates for distributed eco-hydrological modelling in Mediterranean forest basins. On one hand, this study contributes to fill the existing research gap on the use of remote sensing SSM spatial patterns within the distributed hydrological modelling framework in small basins. On the other hand, it serves as an indirect validation method for the spatial performance of satellite SSM products. To achieve this goal, we implemented the eco-hydrological model TETIS in three case studies named: Hozgarganta (southern Spain), Ceira (western Portugal) and Carraixet (eastern Spain). The SSM estimates selected for comparison were Sentinel-1 SSM provided by the Copernicus Global Land Services (CGLS), SMAP SSM disaggregated using Sentinel-1 (SPL2SMAP_S) provided by the National Aeronautics and Space Administration (NASA), SMOS SSM provided by the Barcelona Expert Center (BEC), and SMOS and SMAP SSM disaggregated using the DISPATCH algorithm provided by Lobelia Earth. The methodology employed involved a multi-objective and multi-variable calibration in terms of remote sensing SSM spatial patterns and in-situ streamflow, using the Spatial Efficiency Metric (SPAEF) and the Nash-Sutcliffe efficiency index (NSE) respectively. Before model calibration a sensitivity analysis of the most influent variables was performed. The temporal and spatial comparison of the reference SSM products revealed inconsistencies amongst products. The disaggregating methodology determined the spatial agreement to a greater degree than the sensor itself (i.e. SMAP, SMOS). In spite of the differences amongst products, the multi-objective calibration approach proposed increased the robustness of the hydrological modelling.This study was founded by the Spanish AEI within the program WaterJPI through the project iAqueduct (PCI2019-103729) , by the EC Life project ResilientForests (LIFE17 CCA/ES/000063) , and by the project Water4Cast funded by Generalitat Valenciana (PROMETEO/2021/074) . We also acknowledge the following hydrometeorological data providers institutions: SiAR, SAIH-HIDROSUR, SAIH Jucar and SNIRH.Gomis-Cebolla, J.; Garcia-Arias, A.; Perpinyà-Vallès, M.; Francés, F. (2022). Evaluation of Sentinel-1, SMAP and SMOS surface soil moisture products for distributed eco-hydrological modelling in Mediterranean forest basins. Journal of Hydrology. 608:1-19. https://doi.org/10.1016/j.jhydrol.2022.12756911960

Noise control by sonic crystal barriers made of recycled materials

A systematic study of noise barriers based on sonic crystals made of cylinders that use recycled materials like absorbing component is here reported. The barriers consist of only three rows of perforated metal shells filled with rubber crumb. Measurements of reflectance and transmittance by these barriers are reported. Their attenuation properties result from a combination of sound absorption by the rubber crumb and reflection by the periodic distribution of scatterers. It is concluded that porous cylinders can be used as building blocks whose physical parameters can be optimized in order to design efficient barriers adapted to different noisy environments

Tomografía de emisión de fotones cerebral. Valor del índice corticocerebeloso y patrones gammagráficos en la enfermedad de Alzheimer y otras afecciones

Brain single photon emission computed tomography (SPECT) with 99mTc-HMPAO is a diagnostic tool for evaluating regional cerebral blood flow. Recently, the diagnostic possibilities of the method are being investigated in some neurologic disorders, such as cerebrovascular accidents, seizures and dementia. This work has been carried out with 54 subjects, 9 healthy volunteers and 45 patients (31 dementia and 14 epileptics), in order to evaluate gammagraphic patterns and the utility of cortico/cerebellar activity indexes. An interesting diagnostic finding is a significant decrease (p less than 0.001) in perfusion of temporoparietal regions in the patients with Alzheimer's disease in relation with the healthy volunteers' group. We have not found significant changes in perfusion in the group of epileptic patients during the interictal phase. We conclude emphasizing the interest of the SPECT in the differential diagnosis of dementia

Tailoring activated carbons for the development of specific adsorbents of gasoline vapors

The specific adsorption of oxygenated and aliphatic gasoline components onto activated carbons (ACs) was studied under static and dynamic conditions. Ethanol and n-octane were selected as target molecules. A highly porous activated carbon (CA) was prepared by means of two processes: carbonization and chemical activation of olive stone residues. Different types of oxygenated groups, identified and quantified by TPD and XPS, were generated on the CA surface using an oxidation treatment with ammonium peroxydisulfate and then selectively removed by thermal treatments, as confirmed by TPD results. Chemical and porous transformations were carefully analyzed throughout these processes and related to their VOC removal performance. The analysis of the adsorption process under static conditions and the thermal desorption of VOCs enabled us to determine the total adsorption capacity and regeneration possibilities. Breakthrough curves obtained for the adsorption process carried out under dynamic conditions provided information about the mass transfer zone in each adsorption bed. While n-octane adsorption is mainly determined by the porosity of activated carbons, ethanol adsorption is related to their surface chemistry, and in particular is enhanced by the presence of carboxylic acid groups.This work is supported by the MICINN-FEDER, project CTM2010-18889

Spanish study of anticoagulation in haemodialysis

This study's objectives were to determine which anticoagulation methods are commonly used in patients who are undergoing haemodialysis (HD) in Spain, on what criteria do they depend, and the consequences arising from their use. MATERIAL AND METHOD: Ours was a cross-sectional study based on two types of surveys: a "HD Centre Survey" and a "Patient Survey". The first survey was answered by 87 adult HD units serving a total of 6093 patients, as well as 2 paediatric units. Among these units, 48.3% were part of the public health system and the remaining 51.7% units were part of the private health system. The patient survey analysed 758 patients who were chosen at random from among the aforementioned 78 HD units. RESULTs: A) HD Centre Survey: The majority of adult HD units (n=61, 70.2%) used both kinds of heparin, 19 of them (21.8%) only used LMWH and 7 of them (8%) only used UFH. The most frequently applied criteria for the use of LMWH were medical indications (83.3% of HD units) and ease of administration (29.5%). The most frequently used methods for adjusting the dosage were clotting of the circuit (88.2% of units), bleeding of the vascular access after disconnection (75.3%), and patient weight (57.6%). B) Patient Survey: The distribution of the types of heparin used was: UFH: 44.1%, LMWH: 51.5%, and dialysis without heparin in 4.4% of patients. LMWH was more frequently used in public medical centres (64.2% of patients) than in private medical centres (46.1%) (P<.001). LMWH was more frequently used in on-line haemodiafiltration (HF) than in high-flux HD (P<.001). Antiplatelet agents were given to 45.5% of patients, oral anticoagulants to 18.4% of patients, and both to 5% of patients. Additionally, 4.4% of patients had suffered bleeding complications during the previous week, and 1.9% of patients suffered thrombotic complications. Bleeding complications were more frequent in patients with oral anticoagulants (P=.001), although there was no association between the type of heparin and the occurrence of bleeding or thrombotic complications. CONCLUSIONS: We are able to conclude that there is a great amount of disparity in the criteria used for the medical prescription of anticoagulation in HD. It is advisable that each HD unit revise their own results as well as those from other centres, and possibly to create an Anticoagulation Guide in Haemodialysis