Multi-Agent System Development Based on Organizations

Organizational models have been recently used in agent theory for modeling coordination in open systems and to ensure social order in multi-agent system applications. In this paper, we propose the employment of Organization Theory for the analysis and design of multiagent systems. Thus, we first discuss the current state of the art of organization-oriented multiagent system methods, placing emphasis on their organizational features. We also review human organizational structures, and we propose several guidelines for implementing agent organizations by means of Organization Theory. Our final aim is to employ well-known human organizational structures to develop multiagent systems.     

Ground measurements for the validation of land surface temperatures derived from AATSR and MODIS data

An experimental site was set up in a large, flat and homogeneous area of rice crops for the validation of satellite derived land surface temperature (LST). Experimental campaigns were held in the summers of 2002-2004, when rice crops show full vegetation cover. LSTs were measured radiometrically along transects covering an area of 1 km². A total number of four thermal radiometers were used, which were calibrated and inter-compared through the campaigns. Radiometric temperatures were corrected for emissivity effects using field emissivity and downwelling sky radiance measurements. A database of ground-based LSTs corresponding to morning, cloud-free overpasses of Envisat/Advanced Along-Track Scanning Radiometer (AATSR) and Terra/Moderate Resolution Imaging Spectroradiometer (MODIS) is presented. Ground LSTs ranged from 25 to 32 °C, with uncertainties between ± 0.5 and ± 0.9 °C. The largest part of these uncertainties was due to the spatial variability of surface temperature. The database was used for the validation of LSTs derived from the operational AATSR and MODIS split-window algorithms, which are currently used to generate the LST product in the L2 level data. A quadratic, emissivity dependent split-window equation applicable to both AATSR and MODIS data was checked as well. Although the number of cases analyzed is limited (five concurrences for AATSR and eleven for MODIS), it can be concluded that the split-window algorithms work well, provided that the characteristics of the area are adequately prescribed, either through the classification of the land cover type and the vegetation cover, or with the surface emissivity. In this case, the AATSR LSTs yielded an average error or bias of − 0.9 °C (ground minus algorithm), with a standard deviation of 0.9 °C. The MODIS LST product agreed well with the ground LSTs, with differences comparable or smaller than the uncertainties of the ground measurements for most of the days (bias of + 0.1 °C and standard deviation of 0.6 °C, for cloud-free cases and viewing angles smaller than 60°). The quadratic split-window algorithm resulted in small average errors (+ 0.3 °C for AATSR and 0.0 °C for MODIS), with differences not exceeding ± 1.0 °C for most of the days (standard deviation of 0.9 °C for AATSR and 0.5 °C for MODIS).     

Programming the data path in network processor‐based routers

There is growing interest in network processor technologies capable of processing packets at line rates. Network processors are likely to be an integral part of next generation high‐speed router and switch architectures, replacing the application‐specific integrated circuits (ASICs) that are used in routers today. In this paper, we present the design, implementation and evaluation of NetBind, a high‐performance, flexible and scalable binding tool for dynamically constructing data paths in network processor‐based routers. The methodology that underpins NetBind balances the flexibility of network programmability against the need to process and forward packets at line speeds. To support the dynamic binding of components with the minimum addition of instructions in the critical path, NetBind modifies the machine language code of components at run time. To support fast data path composition, NetBind reduces the number of binding operations required for constructing data paths to a minimum set so that binding latencies are comparable with packet forwarding times. Data paths constructed using NetBind seamlessly share the resources of the same network processor. Resources are assigned during the binding process. We compare the performance of NetBind to the MicroACE system developed by Intel and show that NetBind provides better performance in comparison to MicroACE with smaller binding overhead. The NetBind source code described and evaluated in this paper is freely available on the Web ( http://www.comet.columbia.edu/genesis/netbind ) for experimentation. Copyright © 2005 John Wiley & Sons, Ltd.     

A study of Light's criteria and possible modifications for distinguishing exudative from transudative pleural effusions

STUDY OBJECTIVE: To determine the usefulness of modifying Light's criteria for the separation of pleural transudates from exudates. DESIGN: Retrospective review of patients who underwent a diagnostic thoracentesis during a 2-year period. SETTING: Community teaching hospital in Lleida, Spain. PATIENTS AND METHODS: Clinical records and pleural fluid characteristics of 230 consecutive patients with pleural effusion underwent a detailed review. Thirty-five of these patients were excluded from the analysis. As suggested recently by Romero et al, different cutoff levels for the criteria of Light et al were applied and their accuracies were calculated. RESULTS: Thirty-nine (20%) pleural effusions were transudates and 156 (80%) were exudates. The accuracy of the criteria of Light et al for identifying exudates was 94.7% (confidence interval, 91.6 to 97.9) in comparison to our own modified criteria (93.1%; confidence interval, 89.5 to 96.7) and the criteria suggested by Romero et al (92.6%; confidence interval, 88.9 to 96.3). These differences were not statistically significant. CONCLUSION: Changing the classic Light's criteria with different cutoff points offers no advantages for discriminating between transudative and exudative pleural effusions.     

Rectal hemorrhage as a first sign of renal cell adenocarcinoma

We present a 3-year-old patient with stenotic kinking of the left internal carotid artery (ICA) who developed an ischaemic infarction of the left brain hemisphere followed by severe neurological sequelae after a prolonged generalized seizure. At time of the seizure the boy was in biological remission of a nephrotic syndrome and received prednisolone and cyclosporin A (CsA) treatment. The haemodynamic consequences of inborn kinking of the ICA is discussed controversely in the literature. The presented case shows that stenotic kinking of the ICA may significantly impair the blood flow towards the homolateral hemisphere and therefore may result in an ischaemic infarction. The influence of CsA on seizure activity is discussed. CONCLUSION: This case provides clinical and radiological evidence supporting an association between stenotic kinking of the carotid artery and homolateral hemispheric brain infarction.     

Transient heat conduction problems using B.I.E.M.

A method, using boundary elements, is presented as a solution to plane transient heat conduction. The proposed method considers the governing equation to be a Helmholtz's equation and solves the problem of time variation using step by step integration. A numerical procedure is developed and its effectiveness verified. Several examples are provided and their results compared with the theoretical ones.     

Polycyclic aromatic hydrocarbon content in commercial Spanish fatty foods

The levels of polycyclic aromatic hydrocarbons (PAHs) were determined by reversed-phase high-performance liquid chromatography with fluorescence detection in different fatty foods from a Spanish market. The average concentration of the sum of total PAHs in edible vegetable oils was below 25 ng/g, whereas the sum of heavy PAHs did not surpass 5 ng/g. Olive pomace oils obtained before the summer of 2001 were an exception because they were highly contaminated. The effects of different technological processes, such as bleaching, deodorization, and hydrogenation, on PAH concentration in edible oils have been studied. The PAH profiles, as well as the influence of cooking procedures, of other fatty foods (margarine, mayonnaise, and oils from canned fishes) have been examined.     

Determination of linear alkylbenzenesulfonates and their degradation products in soils by liquid chromatography-electrospray-ion trap multiple-stage mass spectrometry

Linear alkylbenzenesulfonates (LAS) (C(10)-C(13)) and their degradation products, sulfophenyl carboxylate compounds (SPCs) (C(2)-C(6), C(8), C(11)), have been extracted from soil samples with methanol, isolated, concentrated by solid-phase extraction, and determined by liquid chromatography/negative ion electrospray quadrupole ion-trap tandem mass spectrometry (MS(n)). The ion fragmentation processes and pathways were studied in detail by MS, MS(2), and MS(3). Upon collision-induced dissociation, the deprotonated molecules of LASs render the ethylene-substituted benzenesulfonate ion (m/z 183), the fragmentation of which gave the intense signal at m/z 119, corresponding to the ethylene-substituted phenoxide ion formed by the loss of sulfur dioxide. The fragmentation pattern of SPCs shows that, for the analytes of large carbon atom chains (>5C), the neutral loss of water is favored whereas for those of short carbon atoms chain, the loss of carbon dioxide is more frequent. Multiple reaction monitoring using isolation only for MS and using isolation and fragmentation for MS(2) and MS(3) were used to identify and quantify each compound. The three MS modes have been validated in terms of sensitivity, selectivity, and precision, showing that each MS stage used reduces sensitivity 10 times. Recoveries from soil were higher than 65% at LOQ level for all the analytes tested, except for C(2)-C(4) SPCs by any MS mode, with relative standard deviation lower than 19%. The utility of the method is demonstrated by successfully quantifying real samples treated with these products. Quantification limits for the methodology developed in this work ranged from 0.5 to 50 microg kg(-1) by MS, from 2 to 400 microg kg(-1) by MS(2), and from 20 to 4000 microg kg(-1) by MS(3). Concentration levels of LASs and SPCs-ranging from 0.1 to 15 mg kg(-1)-were found in soil samples amended with sludges, thus indicating their input and persistence in the soil compartment.