121 research outputs found
Model Driven Mutation Applied to Adaptative Systems Testing
Dynamically Adaptive Systems modify their behav- ior and structure in
response to changes in their surrounding environment and according to an
adaptation logic. Critical sys- tems increasingly incorporate dynamic
adaptation capabilities; examples include disaster relief and space exploration
systems. In this paper, we focus on mutation testing of the adaptation logic.
We propose a fault model for adaptation logics that classifies faults into
environmental completeness and adaptation correct- ness. Since there are
several adaptation logic languages relying on the same underlying concepts, the
fault model is expressed independently from specific adaptation languages.
Taking benefit from model-driven engineering technology, we express these
common concepts in a metamodel and define the operational semantics of mutation
operators at this level. Mutation is applied on model elements and model
transformations are used to propagate these changes to a given adaptation
policy in the chosen formalism. Preliminary results on an adaptive web server
highlight the difficulty of killing mutants for adaptive systems, and thus the
difficulty of generating efficient tests.Comment: IEEE International Conference on Software Testing, Verification and
Validation, Mutation Analysis Workshop (Mutation 2011), Berlin : Allemagne
(2011
Estimating an Ex Ante Cost Function for Belgian Arable Crop Farms
We estimate a farm-level cost function for Belgian crop farms using FADN data over the study period 1996-2006. We rely on an estimation of farmers' expected yields at the time cropping decisions are made rather than actual yields observed in the FADN data. The use of an ex ante cost function improves the cost function estimation. We subsequently suggest how our cost function can be used in simulations to analyze farmer response to changes in output price risk.cost function estimation, panel data, risk, Agricultural and Food Policy, Crop Production/Industries, Production Economics, Q12, Q18,
Test them all, is it worth it? Assessing configuration sampling on the JHipster Web development stack
Many approaches for testing configurable software systems start from the same assumption: it is impossible to test all configurations. This motivated the definition of variability-aware abstractions and sampling techniques to cope with large configuration spaces. Yet, there is no theoretical barrier that prevents the exhaustive testing of all configurations by simply enumerating them if the effort required to do so remains acceptable. Not only this: we believe there is a lot to be learned by systematically and exhaustively testing a configurable system. In this case study, we report on the first ever endeavour to test all possible configurations of the industry-strength, open source configurable software system JHipster, a popular code generator for web applications. We built a testing scaffold for the 26,000+ configurations of JHipster using a cluster of 80 machines during 4 nights for a total of 4,376 hours (182 days) CPU time. We find that 35.70% configurations fail and we identify the feature interactions that cause the errors. We show that sampling strategies (like dissimilarity and 2-wise): (1) are more effective to find faults than the 12 default configurations used in the JHipster continuous integration; (2) can be too costly and exceed the available testing budget. We cross this quantitative analysis with the qualitative assessment of JHipster’s lead developers.</p
Test them all, is it worth it? Assessing configuration sampling on the JHipster Web development stack
Many approaches for testing configurable software systems start from the same
assumption: it is impossible to test all configurations. This motivated the
definition of variability-aware abstractions and sampling techniques to cope
with large configuration spaces. Yet, there is no theoretical barrier that
prevents the exhaustive testing of all configurations by simply enumerating
them, if the effort required to do so remains acceptable. Not only this: we
believe there is lots to be learned by systematically and exhaustively testing
a configurable system. In this case study, we report on the first ever
endeavour to test all possible configurations of an industry-strength, open
source configurable software system, JHipster, a popular code generator for web
applications. We built a testing scaffold for the 26,000+ configurations of
JHipster using a cluster of 80 machines during 4 nights for a total of 4,376
hours (182 days) CPU time. We find that 35.70% configurations fail and we
identify the feature interactions that cause the errors. We show that sampling
strategies (like dissimilarity and 2-wise): (1) are more effective to find
faults than the 12 default configurations used in the JHipster continuous
integration; (2) can be too costly and exceed the available testing budget. We
cross this quantitative analysis with the qualitative assessment of JHipster's
lead developers.Comment: Submitted to Empirical Software Engineerin
Genetic structure of drone congregation areas of Africanized honeybees in southern Brazil
As yet, certain aspects of the Africanization process are not well understood, for example, the reproductive behavior of African and European honeybees and how the first Africanized swarms were formed and spread. Drone congregation areas (DCAs) are the ideal place to study honeybee reproduction under natural conditions since hundreds of drones from various colonies gather together in the same geographical area for mating. In the present study, we assessed the genetic structure of seven drone congregations and four commercial European-derived and Africanized apiaries in southern Brazil, employing seven microsatellite loci for this purpose. We also estimated the number of mother-colonies that drones of a specific DCA originated from. Pairwise comparison failed to reveal any population sub-structuring among the DCAs, thus indicating low mutual genetic differentiation. We also observed high genetic similarity between colonies of commercial apiaries and DCAs, besides a slight contribution from a European-derived apiary to a DCA formed nearby. Africanized DCAs seem to have a somewhat different genetic structure when compared to the European
Adenine nucleotide translocation in liver mitochondria of hypothyroid rats
In measurements using a disc filtration method, liver mitochondria obtained from hypothyroid rats translocate external ADP at 0 [deg]C via the atractyloside-sensitive carrier much more slowly than do mitochondria from normal rats, confirming the findings of Portnay et al. (Biochem. Biophys. Res. Commun. 55, 17, 1973). The hypothyroid mitochondria contain 60% more ATP + ADP than do mitochondria from normals, but the excess nucleotides are not exchangeable and so do not contribute to translocation. A decrease in the first-order rate constant accounts for the decreased velocity. Neither a decrease in the number of translocator sites nor changes in ADP phosphorylation or ATPase activity seem to account for the abnormal kinetics of translocation. Although the filtration method limits the maximal translocation rate observed in normal mitochondria at temperatures above 17 [deg]C that induce a fluid membrane state, no such transition is seen in mitochondria from hypothyroid rats up to 35 [deg]C, indicating that the translocator is in an altered environment in hypothyroidism. Injecting a hypothyroid rat once with -thyroxine corrects the abnormal compartmentation and produces a temperature-rate relationship like that in normal mitochondria in 3 days, a period which would accommodate the hormone actions reported on translation, membrane phospholipid synthesis, or fatty acid desaturation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22994/1/0000562.pd
Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.
RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Crises psychogènes non épileptiques : étude de la sémiologie des crises et des antécédents traumatiques
REIMS-BU Santé (514542104) / SudocSudocFranceF
De la haie au paysage, introduction au bocage
National audienceLes paysages français comportent une grande diversité de formes et d’origines. Systèmes complexes et évolutifs, ils sont dans la majorité des situations modelés par les activités humaines. Parmi les paysages agraires caractéristiques de nombreuses régions françaises, notamment de l’ouest et du centre, figure le bocage ; fruit d’une longue coévolution entre les humains et la nature au fil des siècles, il est étroitement lié aux progrès de l’agriculture
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