1,850 research outputs found
Costs and benefits of multiple levels of models in MDA development
In Model-Driven Architecture (MDA) development, models of a distributed application are carefully defined so as to remain stable in face of changes in technology platforms. As we have argued previously in [1, 3], models in MDA can be organized into different levels of platformindependence. In this paper, we analyze the costs and benefits of maintaining separate levels of models with transformations between these levels. We argue that the number of levels of models and the degree of automation of transformations between these levels depend on a number of design goals to be balanced, including those of maximizing the efficiency of the design process and maximizing the reusability of models and transformations
Abstract Platform and Transformations for Model-Driven Service-Oriented Development
In this paper, we discuss the use of abstract platforms and transformation for designing applications according to the principles of the service-oriented architecture. We illustrate our approach by discussing the use of the service discovery pattern at a platform-independent design level. We show how a trader service can be specified at a high-level of abstraction and incorporated in an abstract platform for service-oriented development. Designers can then build platform-independent models of applications by composing application parts with this abstract platform. Application parts can use the trader service to publish and discover service offers. We discuss how the abstract platform can be realized into two target platforms, namely Web Services (with UDDI) and CORBA (with the OMG trader)
The role of the service concept in model-driven applications development
This paper identifies two paradigms that have influenced the design of distributed applications: the middleware-centred and the protocol-centred paradigm, and proposes a combined use of these two paradigms. This combined use incorporates major benefits from both paradigms: the ability to reuse middleware infrastructures and the ability to treat distributed coordination aspects as a separate object of design through the use of the service concept. A careful consideration of the service concept, and its recursive application, allows us to define an appropriate and precise notion of platform-independence that suits the needs of model-driven middleware application development
Gas exchange in the salt marsh species Atriplex portulacoides L. and Limoniastrum monopetalum L. in Southern Portugal
Salt marshes are ecosystems subjected to a
variety of environmental stresses like high salinity, water
deficit, intense radiation or high temperatures. Field measurements
were conduced in two halophyte species, Atriplex
portulacoides L. and Limoniastrum monopetalum L., in the
Reserva Natural do Sapal de Castro Marim, to compare their
physiological response, i.e., water potential (w), net photosynthetic
rate (A), stomatal conductance (gs) under natural
conditions. Both species demonstrated marked variations in
w throughout the year, with very low values in the summer,
the period of higher salinity, drought and temperature. Deficit
water potential (Dw = wmidday wpredawn) was lower in
the summer than in other seasons in A. portulacoides but not
in L. monopetalum. The highest values for A and gs in
L. monopetalum were observed in autumn and for A. portulacoides
in winter, presenting both lowest values in spring
and summer. Amax was particularly high for L. monopetalum
than for A. portulacoides in summer and autumn, despite
gsmax was similar in both species. Diurnal pattern ofAand gs
were similar in both species, with higher values in the
morning, decreasing throughout the day
Dry matter and area partitioning, radiation interception and radiation-use efficiency in open-field bell pepper
The objective of this study was to determine some key components of a model for bell pepper growth and
yield under non-limiting water and nutrient conditions using data from field trials conducted in
Southern Portugal. DM partitioning, at least before fruiting, and specific area indices for leaves, stems
and fruits were conservative in relation to normalized thermal time. The interception model had a good
performance. It was based on the exponential extinction of radiation on the area covered by the plants,
the ellipsoidal leaf-angle distributionmodel (X-parameter 2.48 and 2.89), and absorptivities of the leaves
for PAR and NIR, 0.8 and 0.2, respectively. Radiation-use efficiency (RUE) was determined and presented
in four different forms. RUE did not change substantially throughout the growing season. RUE of irrigated
pepper crops grown in our experiments was around 1.6 g MJ 1 of intercepted PAR. The models and
parameter values presented in this study may be useful to simulate the development and growth of fieldgrown
pepper cro
Utilização agrícola e compostagem de lamas de origem têxtil
Utilização agrícola e compostagem de lamas de origem têxtil
Valorização agrícola de lamas de origem têxtil
Valorização agrícola de lamas de origem têxtil
Mineralocorticoid receptor antagonism in acutely decompensated chronic heart failure
Spironolactone was likely to provide faster congestion relief.
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Abstract
Background/objectives
Mineralocorticoid receptor antagonist (MRA) use in acutely decompensated chronic heart failure (ADCHF) may improve congestion through diuretic effect and prevent neurohormonal activation. We aimed to evaluate the clinical effect and safety of spironolactone in ADCHF.
Methods
Prospective, experimental, single-center, and single-blinded trial. Patients were treated with: standard ADCHF therapy or oral spironolactone 50–100 mg/d plus standard ADCHF therapy.
Results
During a 1 year period, 100 patients were enrolled, 50 included in the treatment group. Mean (SD) spironolactone dose (mg) at day 1 was 94.5 ± 23.3 and at day 3 was 62.7 ± 24.3. Worsening renal function (increase in pCr ≥ 0.3 mg/dL from day 1 to day 3) was more likely to occur in control group (20% vs. 4%; p = 0.038), serum potassium did not differ between groups, and plasma NTproBNP had a significant decrease in spironolactone group at day 3 (median [IQR], 2488 [4579] vs. 1555 [1832]; p = 0.05). Furthermore, a greater proportion of patients in the treatment group were free of congestion at day 3: less edema, rales, jugular venous pressure (JVP) and orthopnea (all, p < 0.05). In addition, a significantly higher proportion of patients were on oral furosemide at day 3 (44% vs. 82%; p < 0.001).
Conclusions
Our study supports the safety of high dose spironolactone in ADCHF and suggests a positive impact in the resolution of congestion. The important findings of our pilot study need to be confirmed in larger trials
Mob Rulers And Part-time Cleaners: Two Reef Fish Associations At The Isolated Ascension Island
Isolated oceanic islands may give rise not only to new and endemic species, but also to unique behaviours and species interactions. Multi-species fish interactions, such as cleaning, following, mob-feeding and others are understudied in these ecosystems. Here we present qualitative and quantitative observations on cleaning and mob-feeding reef fish associations at the isolated Ascension Island, South Atlantic Ocean. Cleaning interactions were dominated by juveniles of the facultative fish cleaners Bodianus insularis and Pomacanthus paru, with lesser contributions of Chaetodon sanctaehelenae, Thalassoma ascensionis and the cleaner shrimp Lysmata grabhami. Two types of feeding mobs were consistently identified: less mobile mobs led by the surgeonfish Acanthurus bahianus and A. coeruleus and the more mobile mobs led by the African sergeant Abudefduf hoefleri. This is the first record of A. hoefleri from outside of the Eastern Atlantic and also the first report of this species displaying mob-feeding behaviour. The principal follower of both mob types was the extremely abundant Melichthys niger, but the main aggressor differed: Stegastes lubbocki, a highly territorial herbivore, was the main aggressor of Acanthurus mobs; and Chromis multilineata a territorial fish while engaged in egg parental care, was the principal aggressor towards Abudefduf mobs. Our study enhances the scarce information on reef fish feeding associations at the isolated Ascension Island and at oceanic islands in the Atlantic in general. Copyright © Marine Biological Association of the United Kingdom 201611
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