410 research outputs found
Structural Modelling and Numerical Analysis of the Palace of Sports of Mexico City
The palace of sports represents in many ways the masterpiece from the urbanarchitectural legacy that was created for the XIX Olympiad in Mexico City in 1968; its uniqueness, from the architectural and structural point of view, makes it one of the most iconic buildings of the city. In this paper the structural modelling and numerical analysis of this iconic building of the Mexican architecture of the second part of the XX century is presented. The numerical modelling is achieved by means of a 3D finite element model in order to obtain preliminary results in terms of dynamic properties and linear and non-linear response of structural elements when subjected to gravity loads. Natural periods of the modes with high participating mass obtained on the numerical model are in well agreement to those of other structures with similar configurations. Nonlinear results show that the structure has a large safety factor under gravitational loads. Finally, recommendations about the improvements that can be applied on the actual FEM model are given based on the results obtained in order to give a better assessment to identify risk scenarios and to prevent them tooccur on such iconic structure
Aperiodicity in one-way Markov cycles and repeat times of large earthquakes in faults
A common use of Markov Chains is the simulation of the seismic cycle in a
fault, i.e. as a renewal model for the repetition of its characteristic
earthquakes. This representation is consistent with Reid's elastic rebound
theory. Here it is proved that in {\it any} one-way Markov cycle, the
aperiodicity of the corresponding distribution of cycle lengths is always lower
than one. This fact concurs with observations of large earthquakes in faults
all over the world
Magnetic detection of sentinel lymph node in papillary thyroid carcinoma: The MAGIC-PAT study results
Introduction: Despite the controversy concerning sentinel lymph node biopsy (SLNB) in papillary thyroid carcinoma (PTC), successful detection rates can be achieved by radioguidance and vital dyeing. However, the drawbacks in both techniques are notable. Magnetic-guided SLNB (mSLNB) using superparamagnetic iron oxide (SPIO) nanoparticles is appealing as an alternative procedure.
Materials and Methods: mSLNB using the Sentimag-Sienna System ® , total thyroidectomy and central compartment dissection (CCD) were performed on all PTC patients. Lymph node involvement was assessed by postoperative pathological examination.
Results: From 2014 to 2016, 33 consecutive patients with PTC were enrolled in the study. A total of 20 patients met the eligibility. mSLNB succeeded in 16 patients, with a detection rate of 80%. A median of two SLN per patient were detected. A median of 10.5 non-sentinel lymph nodes (NSLN) from CCD were examined. Among the patients, 56.25% (9/16) had no metastatic nodes, while 12.5% (2/16) had exclusively SLN involvement. No false negative cases were found. The agreement between SLN and NSLN status was 87.5%. The prediction of NSLN involvement by SLN status showed 100% sensitivity, 81.8% specificity, 71.4% PPV and 100% NPV. Subsequently, mSLNB and the final pathological analysis would discriminate 43.75% (7/16) of patients who would certainly benefit from CCD whilst 56.25% of the total would confirm an unnecessary lymphadenectomy and avoid morbidity.
Conclusion: mSLNB showed satisfactory performance in PTC with clinical-negative nodes. We have shown mSLNB to be a good predictor of central compartment status that can improve the staging and management of PTC patients
Normal-superconducting transition induced by high current densities in YBa2Cu3O7-d melt-textured samples and thin films: Similarities and differences
Current-voltage characteristics of top seeded melt-textured YBa2Cu3O7-d are
presented. The samples were cut out of centimetric monoliths. Films
characteristics were also measured on microbridges patterned on thin films
grown by dc sputtering. For both types of samples, a quasi-discontinuity or
quenching was observed for a current density J* several times the critical
current density Jc. Though films and bulks much differ in their magnitude of
both Jc and J*, a proposal is made as to a common intrinsic origin of the
quenching phenomenon. The unique temperature dependence observed for the ratio
J*/Jc, as well as the explanation of the pre-quenching regime in terms of a
single dissipation model lend support to our proposal.Comment: 10 pages, 10 figures, submitted to Physical Review
Microfluidic and Nanofluidic Cavities for Quantum Fluids Experiments
The union of quantum fluids research with nanoscience is rich with
opportunities for new physics. The relevant length scales in quantum fluids,
3He in particular, are comparable to those possible using microfluidic and
nanofluidic devices. In this article, we will briefly review how the physics of
quantum fluids depends strongly on confinement on the microscale and nanoscale.
Then we present devices fabricated specifically for quantum fluids research,
with cavity sizes ranging from 30 nm to 11 microns deep, and the
characterization of these devices for low temperature quantum fluids
experiments.Comment: 12 pages, 3 figures, Accepted to Journal of Low Temperature Physic
Solar Intranetwork Magnetic Elements: bipolar flux appearance
The current study aims to quantify characteristic features of bipolar flux
appearance of solar intranetwork (IN) magnetic elements. To attack such a
problem, we use the Narrow-band Filter Imager (NFI) magnetograms from the Solar
Optical Telescope (SOT) on board \emph{Hinode}; these data are from quiet and
an enhanced network areas. Cluster emergence of mixed polarities and IN
ephemeral regions (ERs) are the most conspicuous forms of bipolar flux
appearance within the network. Each of the clusters is characterized by a few
well-developed ERs that are partially or fully co-aligned in magnetic axis
orientation. On average, the sampled IN ERs have total maximum unsigned flux of
several 10^{17} Mx, separation of 3-4 arcsec, and a lifetime of 10-15 minutes.
The smallest IN ERs have a maximum unsigned flux of several 10^{16} Mx,
separations less than 1 arcsec, and lifetimes as short as 5 minutes. Most IN
ERs exhibit a rotation of their magnetic axis of more than 10 degrees during
flux emergence. Peculiar flux appearance, e.g., bipole shrinkage followed by
growth or the reverse, is not unusual. A few examples show repeated
shrinkage-growth or growth-shrinkage, like magnetic floats in the dynamic
photosphere. The observed bipolar behavior seems to carry rich information on
magneto-convection in the sub-photospheric layer.Comment: 26 pages, 14 figure
Relation of carbohydrate reserves with the forthcoming crop, flower formation and photosynthetic rate, in the alternate bearing Salustiana sweet orange (Citrus sinensis L.)
[EN] The aim of this work was to assess the relation between carbohydrate levels and flower and fruit production, as well as the role of carbohydrates on CO(2) fixation activity, by analysis of leaves, twigs and roots from the alternate bearing 'Salustiana' cultivar of sweet orange (Citrus sinensis [L.] Osbeck). A heavy crop load (on year) did not affect photosynthesis activity when compared to non-fruiting trees (off year). Fruiting trees accumulated most of the fixed carbon in mature fruits, whilst no accumulation was observed in roots before harvest. Non-fruiting trees transported part of the fixed carbon to the roots and mobilize it for growth processes and, at the end of the season (December), store it as reserves. Reserve carbohydrates accumulation in leaves started by early December for both tree types, showing the same levels in on and off trees until spring bud sprouting. A heavy flowering after an off year caused the rapid mobilization of the stored reserves, which were exhausted at full bloom. We found no evidence on carbon fixation regulation by either fruit demand or carbohydrate levels in leaves. Carbohydrate reserves played little or no role over fruit set, which actually relied on current photosynthesisWe thank Ing. Agr. J.M. Torres (ANECOOP, Valencia, Spain) for providing the orchard facilities and logistic help, the R + D + i Linguistic Assistance Office at the Universidad Politecnica de Valencia for their help in revising this article and Y. Bordon for her cooperation in some experiments. Thanks are due also to Dr. Olivares for the critical review of the manuscript. This research was funded by grants from the Conselleria de Agricultura, Pesca y Alimentacion (GV-CAPA00-11) and the Conselleria diEmpresa, Universitat i Ciencia, Generalitat Valenciana (Grupos 04/059).Monerri Huguet, MC.; Fortunato De Almeida, A.; Molina Romero, RV.; González Nebauer, S.; García Luís, MD.; Guardiola Barcena, JL. (2011). Relation of carbohydrate reserves with the forthcoming crop, flower formation and photosynthetic rate, in the alternate bearing Salustiana sweet orange (Citrus sinensis L.). Scientia Horticulturae. 129(1):71-78. https://doi.org/10.1016/j.scienta.2011.03.009S7178129
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