703 research outputs found
ArCo: the Italian Cultural Heritage Knowledge Graph
ArCo is the Italian Cultural Heritage knowledge graph, consisting of a
network of seven vocabularies and 169 million triples about 820 thousand
cultural entities. It is distributed jointly with a SPARQL endpoint, a software
for converting catalogue records to RDF, and a rich suite of documentation
material (testing, evaluation, how-to, examples, etc.). ArCo is based on the
official General Catalogue of the Italian Ministry of Cultural Heritage and
Activities (MiBAC) - and its associated encoding regulations - which collects
and validates the catalogue records of (ideally) all Italian Cultural Heritage
properties (excluding libraries and archives), contributed by CH administrators
from all over Italy. We present its structure, design methods and tools, its
growing community, and delineate its importance, quality, and impact
Dominated Splitting and Pesin's Entropy Formula
Let be a compact manifold and be a diffeomorphism on
. If is an -invariant probability measure which is absolutely
continuous relative to Lebesgue measure and for
there is a dominated splitting on its orbit ,
then we give an estimation through Lyapunov characteristic exponents from below
in Pesin's entropy formula, i.e., the metric entropy satisfies
where
and
are the Lyapunov
exponents at with respect to Consequently, by using a dichotomy for
generic volume-preserving diffeomorphism we show that Pesin's entropy formula
holds for generic volume-preserving diffeomorphisms, which generalizes a result
of Tahzibi in dimension 2
High H2O content in Pyroxenes of residual mantle Peridotites at a Mid Atlantic ridge segment
Global correlations of mid-ocean-ridges basalt chemistry, axial depth and crustal thickness have been ascribed to mantle temperature variations affecting degree of melting. However, mantle H2O content and elemental composition may also play a role. How H2O is distributed in the oceanic upper mantle remains poorly constrained. We tackled this problem by determining the H2O content of orthopyroxenes (opx) and clinopyroxenes (cpx) of peridotites from a continuous lithospheric section created during 26 Ma at a 11°N Mid-Atlantic Ridge segment, and exposed along the Vema Transform. The H2O content of opx ranges from 119 ppm to 383 ppm; that of cpx from 407 ppm to 1072 ppm. We found anomalous H2O-enriched peridotites with their H2O content not correlating inversely with their degree of melting, although H2O is assumed to be incompatible during melting. Inverse correlation of H2O with Ce, another highly incompatible component, suggests post-melting H2O enrichment. We attribute a major role to post-melting temperature-dependent diffusion of hydrogen occurring above the melting region, where water-rich melt flows faster than residual peridotites through dunitic conduits cross-cutting the uprising mantle. Accordingly, estimates of the H2O content of the MORB mantle source based on H2O in abyssal peridotites can be affected by strong uncertainties
Resilience of community food systems (CFS): co-design as a long-term viable pathway to face crises in neglected territories?
The COVID-19 pandemic has brought on a global crisis, with impacts an ongoing food security and nutrition, exposing the vulnerabilities of our society. However, it can be a time for reflection and an opportunity to propose and stimulate initiatives that are ready to facilitate resilience within the food system. The food to fork must be shortened and diversified where it is viable and feasible, while made affordable for all societal levels. To face these challengers, the community food systems (CFS) approach has a crucial role, since it copes with relevant principles, including the necessities of low-income societies from areas particularly marginalized from mainstream food systems, of which those land areas also can pose as additional insurance just in case of occurrence of whatever crises. Systematizing the components and contributions of CFS can facilitate the advance of strategies to better deal with crises and increase resilience. Therefore, in this paper, through key elements of CFS, we propose a theoretical framework that can be applied by decision makers as a conceptual guide for combating threats to food systems in neglected territories
Invariant manifolds and equilibrium states for non-uniformly hyperbolic horseshoes
In this paper we consider horseshoes containing an orbit of homoclinic
tangency accumulated by periodic points. We prove a version of the Invariant
Manifolds Theorem, construct finite Markov partitions and use them to prove the
existence and uniqueness of equilibrium states associated to H\"older
continuous potentials.Comment: 33 pages, 6 figure
Combination of ultrasound and molecular testing in malignancy risk estimate of Bethesda category IV thyroid nodules: results from a single-institution prospective study
Purpose: Malignancy prediction in indeterminate thyroid nodules is still challenging. We prospectively evaluated whether the combination of ultrasound (US) risk stratification and molecular testing improves the assessment of malignancy risk in Bethesda Category IV thyroid nodules.
Methods: Ninety-one consecutively diagnosed Bethesda Category IV thyroid nodules were prospectively evaluated before surgery by both ACR- and EU-TIRADS US risk-stratification systems and by a further US-guided fine-needle aspiration cytology (FNAC) for the following molecular testing: BRAFV600E, N-RAS codons 12/13, N-RAS codon 61, H-RAS codons 12/13, H-RAS codon 61, K-RAS codons 12/13, and K-RAS codon 61 point-mutations, as well as PAX8/PPARγ, RET/PC1, and RET/PTC 3 rearrangements.
Results: At histology, 37% of nodules were malignant. No significant association was found between malignancy and either EU- or ACR-TIRADS. In total, 58 somatic mutations were identified, including 3 BRAFV600E (5%), 5 N-RAS 12/13 (9%), 13 N-RAS 61 (22%), 7 H-RAS 12/13 (12%), 11 H-RAS 61 (19%), 6 K-RAS 12/13 (10%), 8 K-RAS 61 (14%) mutations and 2 RET/PTC1 (4%), 0 RET/PTC 3 (0%), 3 PAX8/PPARγ (5%) rearrangements. At least one somatic mutation was found in 28% and 44% of benign and malignant nodules, respectively, although malignancy was not statistically associated with the outcome of the mutational test. However, the combination of ACR-, but not EU-, TIRADS with the presence of at least one somatic mutation, was significantly associated with malignant histology (P = 0.03).
Conclusion: US risk stratification and FNAC molecular testing may synergistically contribute to improve malignancy risk estimate of Bethesda category IV thyroid nodules
Evaluation of the CPTEC/AGCM wind forecasts during the hurricane Catarina occurrence
International audienceIn March 2004 occurred the first hurricane registered at South Atlantic Ocean. The system named Catarina begun as an extratropical cyclone and remained quasi-stationary some days over the South Atlantic Ocean. The system displaced westward, acquiring characteristics of a hurricane and hit the Brazilian State of Santa Catarina (SC) between the 27 and the 28 March, causing destruction and deaths. The objective of this paper is to evaluate the Center for Weather Prediction and Climate Studies, Atmospheric Global Circulation Model (CPTEC/AGCM) forecast performance of some synoptic patterns associated with Catarina. The surface wind and reduced Sea Level Pressure (SLP) were examined. Moreover, the implementation of 10-m wind forecast (V10m) was evaluated. This variable was not available in the CPTEC/AGCM during the Catarina occurrence and in this study it was compared with the wind at first sigma-level of the AGCM. The CPTEC-Eta reanalyses were used to comparisons. According to reanalyses, more intense winds were observed in northeast, south and southwest edges of the cyclone. The system was not predicted by the CPTEC/AGCM forecasts longer than 24 h, then the analyses were carried out only for 24 h forecasts. In general, the first sigma-level wind forecasts underestimated the wind magnitude and the cyclone intensity. However, the Catarina formation and its displacement southeastward between the 20 and the 21 March were well represented by the model. The CPTEC/AGCM presents deficiencies to predict the system intensity, but in short-range forecasts it was possible to predict the system formation and its atypical trajectory. The wind results from the new implementation did not exhibit better performance compared with the wind at first sigma-level. These results will be better investigated in the future
A "saddle-node" bifurcation scenario for birth or destruction of a Smale-Williams solenoid
Formation or destruction of hyperbolic chaotic attractor under parameter
variation is considered with an example represented by Smale--Williams solenoid
in stroboscopic Poincar\'{e} map of two alternately excited non-autonomous van
der Pol oscillators. The transition occupies a narrow but finite parameter
interval and progresses in such way that periodic orbits constituting a
"skeleton" of the attractor undergo saddle-node bifurcation events involving
partner orbits from the attractor and from a non-attracting invariant set,
which forms together with its stable manifold a basin boundary of the
attractor.Comment: 7 pages, 7 figures, 1 tabl
Fast-slow partially hyperbolic systems versus Freidlin-Wentzell random systems
We consider a simple class of fast-slow partially hyperbolic dynamical
systems and show that the (properly rescaled) behaviour of the slow variable is
very close to a Friedlin--Wentzell type random system for times that are rather
long, but much shorter than the metastability scale. Also, we show the
possibility of a "sink" with all the Lyapunov exponents positive, a phenomenon
that turns out to be related to the lack of absolutely continuity of the
central foliation.Comment: To appear in Journal of Statistical Physic
- …