1,550 research outputs found
Some Remarks on the Model Theory of Epistemic Plausibility Models
Classical logics of knowledge and belief are usually interpreted on Kripke
models, for which a mathematically well-developed model theory is available.
However, such models are inadequate to capture dynamic phenomena. Therefore,
epistemic plausibility models have been introduced. Because these are much
richer structures than Kripke models, they do not straightforwardly inherit the
model-theoretical results of modal logic. Therefore, while epistemic
plausibility structures are well-suited for modeling purposes, an extensive
investigation of their model theory has been lacking so far. The aim of the
present paper is to fill exactly this gap, by initiating a systematic
exploration of the model theory of epistemic plausibility models. Like in
'ordinary' modal logic, the focus will be on the notion of bisimulation. We
define various notions of bisimulations (parametrized by a language L) and show
that L-bisimilarity implies L-equivalence. We prove a Hennesy-Milner type
result, and also two undefinability results. However, our main point is a
negative one, viz. that bisimulations cannot straightforwardly be generalized
to epistemic plausibility models if conditional belief is taken into account.
We present two ways of coping with this issue: (i) adding a modality to the
language, and (ii) putting extra constraints on the models. Finally, we make
some remarks about the interaction between bisimulation and dynamic model
changes.Comment: 19 pages, 3 figure
Regionalization and connectivity in the Gulf of Cádiz and Alborán Sea implication for marine spatial planning and coastal management
This work proposes a regionalization of marine waters south of the Iberian Peninsula based on empirical orthogonal functions and GIS analysis. The regions identified are consistent and correspond to hydrological mesoscale and macroscale structures well characterized from physical and biological viewpoints. Although it is difficult to determine the boundaries of a fluid continuously moving, the procedure used recognizes the most frequent patterns and can be used to reference geographically the most likely position of the limit among the regions. Once established the regions, the connectivity among them is addressed by means of geostrophic currents derived from altimetry data. The main geostrophic circulation pattern depict an elevate connectivity in the area that might facilitate the conservation and recovering of species, but also imply a higher vulnerability to negative externalities and highlight the need of models, marine spatial planning, and coastal management approaches that includes the pelagic ecosystem and connectivity of the seas. Furthermore, the results confirm that the cooperation between public authorities at different levels (local, regional, state) as well as among riparian countries is essential for marine spatial planning and prevention of potential risk derived from upcoming marine activities in the framework of the 2020 agenda and Blue Growth strategy.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tec
Excitability in a nonlinear magnetoacoustic resonator
We report a nonlinear acoustic system displaying excitability. The considered
system is a magnetostrictive material where acoustic waves are parametrically
generated. For a set of parameters, the system presents homoclinic and
heteroclinic dynamics, whose boundaries define a excitability domain. The
excitable behaviour is characterized by analyzing the response of the system to
different external stimuli. Single spiking and bursting regimes have been
identified.Comment: 4 pages, 5 figure
The Influence of Hybrid Renewable Energy Source Plant Composition on Transmission System Stability
Systematic Review and Meta-Analysis of Medication Reviews Conducted by Pharmacists on Cardiovascular Diseases Risk Factors in Ambulatory Care
Background Pharmacists-led medication reviews (MRs) are claimed to be effective for the control of cardiovascular diseases; however, the evidence in the literature is conflicting. The main objective of this meta-analysis was to analyze the impact of pharmacist-led MRs on cardiovascular disease risk factors overall and in different ambulatory settings while exploring the effects of different components of MRs. Methods and Results Searches were conducted in PubMed, Web of Science, Embase, the Cumulative Index to Nursing and Allied Health Literature, and the Cochrane Library Central Register of Controlled Trials database. Randomized and cluster randomized controlled trials of pharmacist-led MRs compared with usual care were included. Settings were community pharmacies and ambulatory clinics. The classification used for MRs was the Pharmaceutical Care Network Europe as basic (type 1), intermediate (type 2), and advanced (type 3). Meta-analyses in therapeutic goals used odds ratios to standardize the effect of each study, and for continuous data (eg, systolic blood pressure) raw differences were calculated using baseline and final values, with 95% CIs. Prediction intervals were calculated to account for heterogeneity. Sensitivity analyses were conducted to test the robustness of results. Meta-analyses included 69 studies with a total of 11Â 644 patients. Sample demographic characteristics were similar between studies. MRs increased control of hypertension (odds ratio, 2.73; 95% prediction interval, 1.05-7.08), type 2 diabetes mellitus (odds ratio, 3.11; 95% prediction interval, 1.17-5.88), and high cholesterol (odds ratio, 1.91; 95% prediction interval, 1.05-3.46). In ambulatory clinics, MRs produced significant effects in control of diabetes mellitus and cholesterol. For community pharmacies, systolic blood pressure and low-density lipoprotein values decreased significantly. Advanced MRs had larger effects than intermediate MRs in diabetes mellitus and dyslipidemia outcomes. Most intervention components had no significant effect on clinical outcomes and were often poorly described. CIs were significant in all analyses but prediction intervals were not in continuous clinical outcomes, with high heterogeneity present. Conclusions Intermediate and advanced MRs provided by pharmacists may improve control of blood pressure, cholesterol, and type 2 diabetes mellitus, as statistically significant prediction intervals were found. However, most continuous clinical outcomes failed to achieve statistical significance, with high heterogeneity present, although positive trends and effect sizes were found. Studies should use a standardized method for MRs to diminish sources of these heterogeneities
Evaluation of two commercially available rumen buffers derived from calcified seaweed for grazing dairy cows: Pilot trial in commercial farms
Los productos a base de algas marinas calcificadas (CS) se han propuesto como un tampón de pH ruminal alternativo al bicarbonato de sodio. Se ha reportado que el magnesio puede ayudar en el control del pH ruminal, especialmente las formas naturales marinas. Evaluamos la capacidad amortiguadora del pH del rumen y la producción y composición de la leche de dos CS: Acid Buf (AB) y M12 (un CS natural enriquecido con magnesio marino), en vacas lecheras en pastoreo en un diseño de cuadrado latino replicado que involucró 2 granjas con rebaños lecheros en buen estado sanitario y de salud, 2 suplementos y 4 periodos de evaluación de un mes cada uno. Vacas lecheras Holstein Friesian se alimentaron con una ración parcial mixta (PMR) y se suplementaron durante cuatro perÃodos de 30 dÃas cada uno con AB o M12. Se midió la producción total y la composición de la leche en cada granja y cinco vacas en cada rebaño recibieron bolos ruminales para monitorear el pH ruminal, permitiéndonos identificar y monitorear eventos de acidosis ruminal subaguda total (SARA) (es decir = 2 h con pH < 5.8). El pH promedio durante el perÃodo experimental fue 2% mayor (p < 0,05) y el número de eventos SARA por vaca fue menor (p = 0,007) para vacas suplementadas con M12 en comparación con AB. Considerando solo las vacas que desarrollaron eventos SARA, M12 tendió (p = 0,068) a reducir el número de eventos de SARA y su duración en comparación con aquellas vacas suplementadas con AB. La producción y composición de la leche fueron similares entre ambos tampones ruminales en todos los perÃodos
Polymeric fibers with tunable properties Lessons from spider silk
Making artificial fibers inspired in spider silks is considered as one of the milestones in the field of biomimetics. The interest is usually justified by the outstanding tensile properties of natural fibers, but it is usually overlooked that spider silk is endowed with a number of related properties – supercontraction, recovery and the existence of a ground state – that impart the material with additional desirable features, such as the possibility of tuning its mechanical behaviour. In this work we present a review on the experimental analysis and significance of these properties, stressing the contributions of our research group to the field. It is also demonstrated how the knowledge gained in the basic study of the natural material has been essential for the improvement of the properties exhibited by artificially processed bio-inspired silk fiber
The hidden link between supercontraction and mechanical behavior of spider silks
The remarkable properties of spider silks have stimulated an increasing interest in understanding the roles of their composition and processing, as well as in the mass-production of these fibers. Previously, the variability in the mechanical properties of natural silk fibers was a major drawback in the elucidation of their behavior, but the authors have found that supercontraction of these fibers allows one to characterize and reproduce the whole range of tensile properties in a consistent way. The purpose of this review is to summarize these findings.
After a review of the pertinent mechanical properties, the role of supercontraction in recovering and tailoring the tensile properties is explained, together with an alignment parameter to characterize silk fibers. The concept of the existence of a mechanical ground state is also mentioned. These behaviors can be modeled, and two such models–at the molecular and macroscopic levels–are briefly outlined. Finally, the assessment of the existence of supercontraction in bio-inspired fibers is considered, as this property may have significant consequences in the design and production of artificial fibers
Downward pumping of magnetic flux as the cause of filamentary structures in sunspot penumbrae
The structure of a sunspot is determined by the local interaction between magnetic fields and convection near the Sun's surface. The dark central umbra is surrounded by a filamentary penumbra, whose complicated fine structure has only recently been revealed by high-resolution observations. The penumbral magnetic field has an intricate and unexpected interlocking-comb structure and some field lines, with associated outflows of gas, dive back down below the solar surface at the outer edge of the spot. These field lines might be expected to float quickly back to the surface because of magnetic buoyancy, but they remain submerged. Here we show that the field lines are kept submerged outside the spot by turbulent, compressible convection, which is dominated by strong, coherent, descending plumes. Moreover, this downward pumping of magnetic flux explains the origin of the interlocking-comb structure of the penumbral magnetic field, and the behaviour of other magnetic features near the sunspot
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