Influencia de la adición de estaño en el proceso de precipitación en una aleación de Cu-Ni-Zn

ABSTRACT: Influence of tin additions on the precipitation processes in a Cu-Ni-Zn alloys. The influence of 1.1 wt% tin additions on the precipitation hardening of Cu-11 wt% Ni-20 wt% Zn alloy was studied by Differential Scanning Calorimetry (DSC), microhardeness measurements and High Resolution Transmission Electron Microscopy (HRTEM). The calorimetric curves, in the range of temperatures analyzed, show the presence of two exothermic reactions in the ternary alloy, associated to the short-range-order development assisted by migration of excess vacancies. On the other hand, one exothermic and one endothermic reaction are observed in the quaternary alloy, associated to the formation and dissolution of Cu2NiZn precipitates, respectively. It has been show that an addition of 1.1% tin plays an important role in the formation of Cu2NiZn precipitates, responsible for the precipitation hardening of the ternary alloy.Peer Reviewe

Analysis Over the Accuracy of Dynamic Formulas for Predicting Ultimate Load Capacity in Deep Foundations

In Civil Engineering, particularly in Geotechnics, several empirical methods, commonly referred to as dynamic equations, have been proposed for prediction of ultimate load capacity of driven piles. However, these formulas are admitted inaccurate and, so, there is a need to evaluate the results obtained by them. In this work a comparative analysis of the values ​​obtained by five dynamic equations (Janbu, Danish, Gates, FHWA-Gates and WSDOT) with actual ultimate load capacities (obtained through pile load tests at site) is made. Errors are measured using the root mean squared error and the correlation between the equation´s results and the measured values ​​is verified. The results showed important differences between the ultimate capacities obtained from the analyzed models and the real values verified in field tests. It was also verified a superiority, in terms of lower error and greater correlation, of the WSDOT and Danish formulas. Attempts were made to improve the methods. For this, coefficients were determined that, when multiplied by the results of the formulas, promoted a reduction in error. Once again, WSDOT presented best perform in terms of correlation and error

Dental findings in patients with liver cirrhosis. A study of 100 cases

A study was made of the dental findings in 100 patients with liver cirrhosis (LC) by examining the number of carious, missing and filled teeth. A significantly greater number of carious and missing teeth were observed in the patients with cirrhosis than in a control group of 50 healthy individuals. In the LC group, caries were found to affect more teeth in those patients with alcohol-induced LC than in those with liver disease of other causes. Finally, no relationship was observed between the number of carious, missing or filled teeth and certain determinations including serum glutamate pyruvate transaminase (SGPT), serum glutamate oxalacetate transaminase (SGOT), alkaline phosphatase, platelet number, hepatitis B and C positivity markers, or antinuclear (ANA), antimitochondrial (AMA) or anti-smooth muscle autoantibodies (ASm).Une étude des fiches dentaires de 100 patients présentant une cirrhose hépatique (CH) a été réalisée en examinant l’index des dents cariées, manquantes ou plombées. Une augmentation significative du nombre de dents cariées ou manquantes a été observée chez les patients avec cirrhose, par rapport au groupe de référence composé de 50 individus sains. Dans le groupe de CH, les patients avec cirrhose éthylique avaient un plus grand nombre de caries que les autres pour lesquels l’origine de la maladie hépatique était différente. Finalement aucune relation n’a été observée entre l’index des dents cariées, manquantes ou plombées et certaines déterminations analytiques comme les transaminases alanine aminotransférases (ALAT ou SGPT), les transaminases aspartate aminotransférases ( ASAT ou SGOT), les phosphates alcalines, la numération plaquettaire, les marqueurs des hépatites B ou C, ou les anticorps antinucléaires (ANA), anti-mitochondries (AMA) ou antimuscle lisse (ASm)

Las producciones de adorno personal en rocas verdes del SW Peninsular : los casos de Leceia, Moita da Ladra y Penha Verde

Carlos Ribeiro (1813-1882) geólogo e arqueólogo. Homenagem da Câmara Municipal de Oeiras e da Academia das Ciências de Lisboa nos 200 anos do seu nasciment

Small-scale distributions in an indoor environment at 94GHz

[EN] In this paper, an extensive multiple-input multiple-output measurement campaign in a lab environment has been conducted at the 94GHz band. Using a vector network analyzer, updown converters, and omnidirectional antennas displaced in virtual arrays, we have obtained an estimation of the distribution parameters for the most usual distributions employed in the small-scale fading modeling, i.e., Rayleigh, Rice, Nakagami-m and -, by using statistical inference techniques. Moreover, in this scenario the best fit distribution to the experimental data is the Weibull distribution, using the Kolmogorov-Smirnov test. However, the - distribution provides the best fitting to the experimental results in terms of the lower tails of the distributions.This work was supported by the Ministerio de Economia y Competitividad MINECO, Spain (TEC2016-78028-C3-2-P) and by the European FEDER funds. Further information regarding the data obtained and included in this paper can be attained by contacting the author, Jose M. Molina ([email protected]).Reig, J.; Martinez-Ingles, M.; Molina-Garcia-Pardo, J.; Rubio Arjona, L.; Rodrigo Peñarrocha, VM. (2017). Small-scale distributions in an indoor environment at 94GHz. Radio Science. 52(7):852-861. https://doi.org/10.1002/2017RS006335S852861527Cudak, M., Ghosh, A., Kovarik, T., Ratasuk, R., Thomas, T. A., Vook, F. W., & Moorut, P. (2013). Moving Towards Mmwave-Based Beyond-4G (B-4G) Technology. 2013 IEEE 77th Vehicular Technology Conference (VTC Spring). doi:10.1109/vtcspring.2013.6692638Everitt, B. S., & Skrondal, A. (2010). The Cambridge Dictionary of Statistics. doi:10.1017/cbo9780511779633Helminger, J., Detlefsen, J., & Groll, H. (s. f.). Propagation properties of an indoor-channel at 94 GHz. ICMMT’98. 1998 International Conference on Microwave and Millimeter Wave Technology. Proceedings (Cat. No.98EX106). doi:10.1109/icmmt.1998.768215Moon-Soon Choi, Grosskopf, G., & Rohde, D. (s. f.). Statistical Characteristics of 60 GHz Wideband Indoor Propagation Channel. 2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications. doi:10.1109/pimrc.2005.1651506Kajiwara, A. (s. f.). Indoor propagation measurements at 94 GHz. Proceedings of 6th International Symposium on Personal, Indoor and Mobile Radio Communications. doi:10.1109/pimrc.1995.477099Maccartney, G. R., Rappaport, T. S., Sun, S., & Deng, S. (2015). Indoor Office Wideband Millimeter-Wave Propagation Measurements and Channel Models at 28 and 73 GHz for Ultra-Dense 5G Wireless Networks. IEEE Access, 3, 2388-2424. doi:10.1109/access.2015.2486778Marcum J. I. 1950 Table of Q functionsMartinez-Ingles, M.-T., Gaillot, D. P., Pascual-Garcia, J., Molina-Garcia-Pardo, J.-M., Rodríguez, J.-V., Rubio, L., & Juan-Llácer, L. (2016). Channel sounding and indoor radio channel characteristics in the W-band. EURASIP Journal on Wireless Communications and Networking, 2016(1). doi:10.1186/s13638-016-0530-7Rangan, S., Rappaport, T. S., & Erkip, E. (2014). Millimeter-Wave Cellular Wireless Networks: Potentials and Challenges. Proceedings of the IEEE, 102(3), 366-385. doi:10.1109/jproc.2014.2299397Reig, J., Martínez-Inglés, M.-T., Rubio, L., Rodrigo-Peñarrocha, V.-M., & Molina-García-Pardo, J.-M. (2014). Fading Evaluation in the 60 GHz Band in Line-of-Sight Conditions. International Journal of Antennas and Propagation, 2014, 1-12. doi:10.1155/2014/984102Thomas, H. J., Cole, R. S., & Siqueira, G. L. (1994). An experimental study of the propagation of 55 GHz millimeter waves in an urban mobile radio environment. IEEE Transactions on Vehicular Technology, 43(1), 140-146. doi:10.1109/25.282274Thomas, T. A., Vook, F. W., & Sun, S. (2015). Investigation into the effects of polarization in the indoor mmWave environment. 2015 IEEE International Conference on Communications (ICC). doi:10.1109/icc.2015.724851

Mass, Angular Momentum and Thermodynamics in Four-Dimensional Kerr-AdS Black Holes

In this paper, the connection between the Lorentz-covariant counterterms that regularize the four-dimensional AdS gravity action and topological invariants is explored. It is shown that demanding the spacetime to have a negative constant curvature in the asymptotic region permits the explicit construction of such series of boundary terms. The orthonormal frame is adapted to appropriately describe the boundary geometry and, as a result, the boundary term can be expressed as a functional of the boundary metric, extrinsic curvature and intrinsic curvature. This choice also allows to write down the background-independent Noether charges associated to asymptotic symmetries in standard tensorial formalism. The absence of the Gibbons-Hawking term is a consequence of an action principle based on a boundary condition different than Dirichlet on the metric. This argument makes plausible the idea of regarding this approach as an alternative regularization scheme for AdS gravity in all even dimensions, different than the standard counterterms prescription. As an illustration of the finiteness of the charges and the Euclidean action in this framework, the conserved quantities and black hole entropy for four-dimensional Kerr-AdS are computed.Comment: 15 pages,no figures,few references added,JHEP forma

Transgression forms and extensions of Chern-Simons gauge theories

A gauge invariant action principle, based on the idea of transgression forms, is proposed. The action extends the Chern-Simons form by the addition of a boundary term that makes the action gauge invariant (and not just quasi-invariant). Interpreting the spacetime manifold as cobordant to another one, the duplication of gauge fields in spacetime is avoided. The advantages of this approach are particularly noticeable for the gravitation theory described by a Chern-Simons lagrangian for the AdS group, in which case the action is regularized and finite for black hole geometries in diverse situations. Black hole thermodynamics is correctly reproduced using either a background field approach or a background-independent setting, even in cases with asymptotically nontrivial topologies. It is shown that the energy found from the thermodynamic analysis agrees with the surface integral obtained by direct application of Noether's theorem.Comment: 28 pages, no figures. Minor changes in the introduction, final comments and reference

Antithrombotic treatment in elderly patients with atrial fibrillation: A practical approach

Background: Atrial fibrillation (AF) in the elderly is a complex condition. It has a direct impact on the underuse of antithrombotic therapy reported in this population. Discussion: All patients aged =75years with AF have an individual yearly risk of stroke >4%. However, the risk of hemorrhage is also increased. Moreover, in this population it is common the presence of other comorbidities, cognitive disorders, risk of falls and polymedication. This may lead to an underuse of anticoagulant therapy. Direct oral anticoagulants (DOACs) are at least as effective as conventional therapy, but with lesser risk of intracranial hemorrhage. The simplification of treatment with these drugs may be an advantage in patients with cognitive impairment. The great majority of elderly patients with AF should receive anticoagulant therapy, unless an unequivocal contraindication. DOACs may be the drugs of choice in many elderly patients with AF. Summary: In this manuscript, the available evidence about the management of anticoagulation in elderly patients with AF is reviewed. In addition, specific practical recommendations about different controversial issues (i.e. patients with anemia, thrombocytopenia, risk of gastrointestinal bleeding, renal dysfunction, cognitive impairment, risk of falls, polymedication, frailty, etc.) are provided

Counterterms and dual holographic anomalies in CS gravity

The holographic Weyl anomaly associated to Chern-Simons gravity in 2n+1 dimensions is proportional to the Euler term in 2n dimensions, with no contributions from the Weyl tensor. We compute the holographic energy-momentum tensor associated to Chern-Simons gravity directly from the action, in an arbitrary odd-dimensional spacetime. We show, in particular, that the counterterms rendering the action finite contain only terms of the Lovelock type.Comment: 10 pages, no figure