1,782 research outputs found
All Else Being Equal Be Empowered
The original publication is available at www.springerlink.com . Copyright Springer DOI : 10.1007/11553090_75The classical approach to using utility functions suffers from the drawback of having to design and tweak the functions on a case by case basis. Inspired by examples from the animal kingdom, social sciences and games we propose empowerment, a rather universal function, defined as the information-theoretic capacity of an agent’s actuation channel. The concept applies to any sensorimotoric apparatus. Empowerment as a measure reflects the properties of the apparatus as long as they are observable due to the coupling of sensors and actuators via the environment.Peer reviewe
RED-PL, a Method for Deriving Product Requirements from a Product Line Requirements Model
International audienceSoftware product lines (SPL) modeling has proven to be an effective approach to reuse in software development. Several variability approaches were developed to plan requirements reuse, but only little of them actually address the issue of deriving product requirements. Indeed, while the modeling approaches sell on requirements reuse, the associated derivation techniques actually focus on deriving and reusing technical product data.This paper presents a method that intends to support requirements derivation.Its underlying principle is to take advantage of approaches made for reuse PL requirements and to complete them by a requirements development process by reuse for single products. The proposed approach matches users' product requirements with PL requirements models and derives a collection ofrequirements that is (i) consistent, and (ii) optimal with respect to users' priorities and company's constraints. The proposed methodological process was validated in an industrial setting by considering the requirement engineering phase of a product line of blood analyzers
Consumption of dissolved organic carbon by Caribbean reef sponges
Sponges are conspicuous and abundant within the benthic fauna on Caribbean reefs. The ability of these organisms to efficiently capture carbon from particulate sources is well known and the importance of dissolved organic carbon (DOC) uptake has been recognized for several species. We surveyed DOC ingestion by seven sponge species common to Florida Keys reefs using nondisruptive sampling methods on undisturbed individuals. Three of the seven species exhibited significant DOC removal ranging from 13% to 24% of ambient concentrations. The tested species that removed DOC host large microbial consortia within their tissues, while the converse was observed for those that did not. This divergent behavior may suggest an important role for sponge associated microbes in the utilization of DOC by these species. The feeding behaviors of individuals of Xestospongia muta were then monitored over time to investigate its respiratory consumption of particulate and DOC. The uptake rates of dissolved oxygen (DO) and organic carbon by two undisturbed individuals revealed that DOC represented 96% of removed C, and that the tested individuals removed approximately equal quantities of C and DO. This demonstrates that X. muta largely satisfies its respiration demands through DOC consumption, and that DOC likely represents the dominant C source for biomass production and cell overturn in this species. These results further illustrate the metabolic importance of DOC to sponges, and suggest that these organisms are an important pathway for remineralizing organic matter on Caribbean reefs
Reverse Monte Carlo modeling of amorphous silicon
An implementation of the Reverse Monte Carlo algorithm is presented for the
study of amorphous tetrahedral semiconductors. By taking into account a number
of constraints that describe the tetrahedral bonding geometry along with the
radial distribution function, we construct a model of amorphous silicon using
the reverse monte carlo technique. Starting from a completely random
configuration, we generate a model of amorphous silicon containing 500 atoms
closely reproducing the experimental static structure factor and bond angle
distribution and in improved agreement with electronic properties. Comparison
is made to existing Reverse Monte Carlo models, and the importance of suitable
constraints beside experimental data is stressed.Comment: 6 pages, 4 PostScript figure
A search for new members of the βPictoris, Tucana-Horologium and ɛCha moving groups in the RAVE data base
We report on the discovery of new members of nearby young moving groups, exploiting the full power of combining the Radial Velocity Experiment (RAVE) survey with several stellar age diagnostic methods and follow-up high-resolution optical spectroscopy. The results include the identification of one new and five likely members of the βPictoris moving group, ranging from spectral types F9 to M4 with the majority being M dwarfs, one K7 likely member of the εCha group and two stars in the Tucana-Horologium association. Based on the positive identifications, we foreshadow a great potential of the RAVE data base in progressing towards a full census of young moving groups in the solar neighbourhood
Estimated GFR Trajectories in Pediatric and Adult Nephrotic Syndrome: Results From the Nephrotic Syndrome Study Network (NEPTUNE)
56% and 16% had PNL 50%, respectively. In both adults and pediatric patients, higher baseline eGFR was associated with higher PNL, whereas longer follow-up time was associated with lower PNL. Higher urine protein-creatinine ratio and steroid use were also associated with higher PNL in adults. Higher percentages of tubular atrophy and foot-process effacement were associated with lower and higher PNLs, respectively, in adults. Limitations: Relatively short follow-up time, inability to assess acute kidney injury events, and variable eGFR measurement frequency across patients. Conclusions: Although increasing follow-up time resulted in more linear trajectories, nonlinear eGFR trajectories were common in this cohort. Future studies in nephrotic syndrome should consider novel outcomes that do not rely on linearity assumptions.Rationale & Objective: Surrogate outcomes for end-stage kidney disease often assume linear changes, which may not reflect true estimated glomerular filtration rate (eGFR) trajectories. This study's objective was to characterize nonlinear eGFR trajectories in nephrotic syndrome. Study Design: Observational cohort study. Setting & Participants: Nephrotic Syndrome Study Network (NEPTUNE) is a multicenter study of adult and pediatric patients with proteinuria enrolled at clinically indicated kidney biopsy or initial presentation of disease (pediatric only). Predictors: Patient demographic, clinical, and pathology variables at study enrollment and follow-up time. Outcome: eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (patients ≥ 18 years old) or modified Chronic Kidney Disease in Children Study–Schwartz (patients < 18 years) formulas. The probability of nonlinearity (PNL) was calculated for individual eGFR trajectories. Analytical Approach: Associations between predictors and PNL were assessed using multivariable linear regression. Results: 453 patients with ≥3 eGFR measurements and 1 or more year of follow-up were included (median follow-up, 3.6 years). Median PNL was 0.05
- …