378 research outputs found
The representation of the trade winds in ECMWF forecasts and reanalyses during EUREC4A
The characterization of systematic forecast errors in lower-tropospheric winds is an essential component of model improvement. This paper is motivated by a global, long-standing surface bias in the operational medium-range weather forecasts produced with the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). Over the tropical oceans, excessive easterly flow is found. A similar bias is found in the western North Atlantic trades, where the EUREC 4 A field campaign provides an unprecedented wealth of measurements. We analyze the wind bias in the IFS and ERA5 reanalysis throughout the entire lower troposphere during EUREC4 A. The wind bias varies greatly from day to day, resulting in root mean square errors (RMSEs) up to 2.5 m s(-1), with a mean wind speed bias up to -1 m s(-1) near and above the trade inversion in the forecasts and up to -0.5 m s(-1) in reanalyses. These biases are insensitive to the assimilation of sondes. The modeled zonal and meridional winds exhibit a diurnal cycle that is too strong, leading to a weak wind speed bias everywhere up to 5 km during daytime but a wind speed bias below 2 km at nighttime that is too strong. Removing momentum transport by shallow convection reduces the wind bias near the surface but leads to stronger easterly near cloud base. The update in moist physics in the newest IFS cycle (cycle 47r3) reduces the meridional wind bias, especially during daytime. Below 1 km, modeled friction due to unresolved physical processes appears to be too strong but is (partially) compensated for by the dynamics, making this a challenging coupled problem
On the quantum, classical and total amount of correlations in a quantum state
We give an operational definition of the quantum, classical and total amount
of correlations in a bipartite quantum state. We argue that these quantities
can be defined via the amount of work (noise) that is required to erase
(destroy) the correlations: for the total correlation, we have to erase
completely, for the quantum correlation one has to erase until a separable
state is obtained, and the classical correlation is the maximal correlation
left after erasing the quantum correlations.
In particular, we show that the total amount of correlations is equal to the
quantum mutual information, thus providing it with a direct operational
interpretation for the first time. As a byproduct, we obtain a direct,
operational and elementary proof of strong subadditivity of quantum entropy.Comment: 12 pages ReVTeX4, 2 eps figures. v2 has some arguments clarified and
references update
From Things to Services: A Social IoT Approach for Tourist Service Management
In the context of Internet of Things (IoT), the cooperation and synergy between varied and disparate communicating objects is strained by trustworthiness, confidentiality and interoperability concerns. These restrictions can limit the development of IoT-based applications especially considering the emergent boost in the number of communicating objects and their growing itinerant nature in a collective service context. A new perspective arises with the paradigm of Social Internet of Things (SIoT), that relies on the implementation of semi-independent communicating objects with cooperation assessed by social relations and social feed-back. In this article, we present the development and expansion of the IoT concept towards SIoT in the context of the interactions between tourist services as communicating objects. As a proof-of-concept we propose a composition of services as virtualized social objects and the interaction between them, by taking into consideration the balance, trustworthiness, cooperation and synergy of services. Furthermore we present a solution to integrate also accessibility in SIoT services. The presented concept is presented using a demonstrator build for tourist services
TWO RECIPES FROM PORTUGUESE TRADITION OF GILDING ON WOODEN SUPPORT BETWEEN LABORATORY REPRODUCTION AND ANALYTICAL INVESTIGATION
This paper has the main purpose to compile and highlight the first data obtained from
experimental studies on docμmented reconstructions of gilded composites performed within a
research project on gilding materials and techniques in Portugal (www.gilt-teller.pt) funded by
FCT. Two water gilding recipes were appropriately chosen from the treatises written by the
Portuguese Filipe Nunes (1615) and José Lopes Baptista de Almada (1749) as being
representative for Baroque époque. Based on these recipes, the production of raw materials -
“gesso grosso”, “gesso fino”, bole, animal glue (from lamb and goat skins) - was made as
faithful as possible. Their application was then performed in laboratory following the
indications given by these authors or by treatises of previous époques (e.g. the Bolognese
treatise for thawing leather), on plane and curved wooden supports (pine and oak species)
using three types of leaf: gold (Au/Ag/Cu) of 22 and 23.75 karat respectively and silver. After
the completion of gilding, the samples’ surfaces were divided into areas and on each different
finishing layers (wax, animal glue size) and decorations (punching, “esgrafitado”, “estofado”)
were applied. An analytical campaign using optical microscopy (OM) and scanning electron
microscopy (SEM) on surfaces and cross sections, X-ray diffraction (XRD), microcomputerized
tomography (microCT) and colorimetry (CIEL*a*b*) was undertaken in order to
characterize the gilded composites and to assess the faithfulness of the reproductions in the
laboratory. Correlations between the information given by the recipes and the composition and
stratigraphical patterns of the reconstructions can be established. Furthermore, the study aims
to highlight the difficulties encountered in analyzing real samples and comparing the results
with those from reproductions as the number and types of layered materials are not always
reproducible. A critical approach is needed and criteria for faithful reproduction of ancient
recipes are suggested
Outcomes of balloon dilation for paediatric laryngeal stenosis.
Balloon dilation (BD) is a minimally invasive endoscopic treatment for paediatric laryngeal stenosis (LS) with reduced morbidity compared to open surgery. We retrospectively describe our experience in a cohort of children with chronic LS.
Fourteen children (median age: 28.5; range: 2-81 months) with chronic LS (multilevel in 8) were treated with tubeless total intravenous anaesthesia under spontaneous ventilation.
Grade III LS was preoperatively detected in 12 children; the remaining 2 had grade IV stenosis. Six had prior tracheotomy, and one received it during the first intervention. Dilation laryngoplasty was the primary treatment in 11 children and was used as an adjuvant treatment in 3 after open reconstructive surgery. The median number of dilations was 2 (range: 1-6). There were no postoperative complications. At the end of the follow-up (median: 20.5; range: 2-46 months), detectable laryngeal lumen widening and/or respiratory improvement occurred in 12 children. Two of 7 patients with tracheostomy were decannulated.
Balloon laryngoplasty is a valuable therapeutic option to improve laryngeal patency in children with chronic multilevel LS, both as a primary and secondary adjuvant treatment after reconstructive surgery
Enhancement of de Haas-van Alphen Oscillation due to Spin in the Magnetic Breakdown System
The effects of the Zeeman term on the de Haas-van Alphen oscillation is
studied in the magnetic breakdown system. We find that the amplitude of the
oscillation with the frequencies of and are enhanced by the Zeeman term, while they are expected to be
reduced in the semiclassical theory. A possible interpretation of the
experiments in organic conductors is discussed.Comment: 4 pages,4 figures. Submitted to Journal of Physical Society of Japa
A COMPARATIVE MULTI-TECHNIQUE INVESTIGATION ON MATERIAL IDENTIFICATION OF GILDING LAYERS AND THE CONSERVATION STATE OF 7 PORTUGUESE MANNERIST ALTARPIECES
This paper deals with the multi-analytical comparative characterization of 59 samples of
gilded and polychrome layers from 7 altarpieces studied during the Gilt-Teller project
(www.gilt-teller.pt). The altarpieces studied here belong to seven churches in the areas of
Lisbon, Santarém, Portalegre and Guarda and display stylistic and constructive features
characteristic to the Mannerism carved wood decoration in Portugal. The applied protocol of
investigation characterized the structure and manufacture technique of gilding; identified the
chemical composition of the layers constituting the gilded polychrome decoration; compared
the materials and gilding techniques encountered in the 7 altarpieces and assessed the
conservation state of each altarpiece. The analytical techniques applied to these purposes
were: stereomicroscopy (SM), optical microscopy (OM), scanning electron microscopy
coupled with energy dispersive X-ray spectrometry (SEM-EDX), X-ray diffraction (XRD),
MALDI-TOF mass spectrometry, μRaman and μFTIR/imaging μFTIR spectroscopies. This
interdisciplinary multi-scale approach was used to elucidate the aspects related to the material
and technical aspects of “talha dourada” decoration, answering to these questions: which are
the original materials and layers in the making of the polychromy and which are the ones
added with posterior interventions; which are the relationships between gilding materials and
techniques, regarding the degree of erudition of each case study; which were the main causes
of degradation and influence to their conservation condition
The Influence of Neutron Irradiation on (B0.65C0.35)Ba1.4Sr0.6Ca2Cu3Oz Superconducting Phase: the Role of the Grain Edge
Using the transport and magnetization measurements the influence of neutron
irradiation at a fluence of 5x10 n cm on
(B0.65C0.35)Ba1.4Sr0.6Ca2Cu3Oz has been investigated. The neutron irradiation
was found to decrease critical temperature and transport critical current
density, increase the residual and normal state resistivity, and improve the
intragranular critical current density with 1.6x10 A/cm (at 77.3K
and in the applied field up to 160 kA m) and \Delta Mirr/\Delta Mnonirr ratio
(up to factor of 3) at highest field used for investigation. The field
dependence of this ratio, which is below the unity at very low field but higher
than 1 at high fields, correlated with the shape of the hystertic loops as well
as with the change of the transport parameters after irradiation suggests the
role of the irradiation induced effects on the grain edges. We discuss these
effects in the framework of the Bean-Livingstone surface barriers and
geometrical barriers.Comment: 12 pages, 5 figure
Are all noisy quantum states obtained from pure ones?
We ask what type of mixed quantum states can arise when a number of separated
parties start by sharing a pure quantum state and then this pure state becomes
contaminated by noise. We show that not all mixed states arise in this way.
This is even the case if the separated parties actively try to degrade their
initial pure state by arbitrary local actions and classical communication.Comment: 3 pages, no figure
Variational methods
International audienceThis contribution presents derivative-based methods for local sensitivity analysis, called Variational Sensitivity Analysis (VSA). If one defines an output called the response function, its sensitivity to inputs variations around a nominal value can be studied using derivative (gradient) information. The main issue of VSA is then to provide an efficient way of computing gradients. This contribution first presents the theoretical grounds of VSA: framework and problem statement, tangent and adjoint methods. Then it covers pratical means to compute derivatives, from naive to more sophisticated approaches, discussing their various 2 merits. Finally, applications of VSA are reviewed and some examples are presented, covering various applications fields: oceanography, glaciology, meteorology
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