Entanglement and the Lower Bounds on the Speed of Quantum Evolution

The concept of quantum speed limit-time (QSL) was initially introduced as a lower bound to the time interval that a given initial state $\psi_I$ may need so as to evolve into a state orthogonal to itself. Recently [V. Giovannetti, S. Lloyd, and L. Maccone, Phys. Rev. A {\bf 67}, 052109 (2003)] this bound has been generalized to the case where $\psi_I$ does not necessarily evolve into an orthogonal state, but into any other $\psi_F$. It was pointed out that, for certain classes of states, quantum entanglement enhances the evolution "speed" of composite quantum systems. In this work we provide an exhaustive and systematic QSL study for pure and mixed states belonging to the whole 15-dimensional space of two qubits, with $\psi_F$ a not necessarily orthogonal state to $\psi_I$. We display convincing evidence for a clear correlation between concurrence, on the one hand, and the speed of quantum evolution determined by the action of a rather general local Hamiltonian, on the other one.Comment: 19 pages, 5 figure

Valoración clínica de resultados en artrodesis trapecio-metacarpiana: placa atornillada vs agujas de Kirschner

La rizartrosis es una patología frecuente. Cuando el tratamiento conservador es insuficiente, se indica un tratamiento quirúrgico. Existen diversas técnicas, entre las más ampliamente utilizadas está la artrodesis trapeciometacarpiana. Realizamos un estudio retrospectivo 44 casos (57 intervenciones) comparando dos métodos de artrodesis, agujas de Kirschner y placas atornilladas. Se realizó una valoración radiológica, clínica y funcional de los casos para determinar las posibles ventajas de un método sobre otro. La edad media fue 56,5 5,9 años. Se utilizaron 33 agujas Kirschner, 24 placas atornilladas. Mejoría en los resultados de los cuestionarios EVA (4,8 3,4) y DASH (23,2 23,5). El 44,7% movilidad con escala de Kapandji de 10. Se analizaron estadísticamente los datos, no encontrando diferencias significativas entre los dos métodos en cuanto a la consolidación, estado funcional ni complicaciones. En la mayor parte de los casos la clínica disminuye, se mejora la función con una excelente satisfacción del paciente. No hemos encontrado diferencias en nuestro estudio en las variables observadas.Trapezio-metacarpal arthritis is common. In that cases in which has failed to respond to conservative measures we need to use surgical procedures. One of them is the trapeziometacarpal arthrodesis. Retrospectiv study 44 patients (57 arthrodeses), comparing two surgical arthrodesis procedures, K-wires versus plate and screws, to assess the efficacy of these procedures with respect to patient satisfaction, radiological and clinical outcomes. Average age was 56.5 5.9 years. 33 K-wires, 24 plate and screws. There were an improvement in quetionaires results VAS (4.8 3.4) and DASH (23.2 23.5). The 44.7 % of patients scored a 10 in Kapandji test. We found no statistical differencees between these procedures in non-union rate, functional outcome or complications. For most patients Trapeziometacarpal arthrodesis reduces pain, improves function and results in excellent patient satisfaction. We have found no differences between these procedures in our study

Development of Novel DNA Cleavage Systems Based on Copper Complexes. Synthesis and Characterisation of Cu(II) Complexes of Hydroxyflavones

Copper(II) complexes of several hydroxyflavones were prepared and characterised through their physico-chemical properties. The nuclease activity of three synthesised complexes is reported. These copper(II) complexes present more nuclease activity than the ligands and the copper(II) ion

Magnetic exchange interaction in a pair of orbitally degenerate ions: Magnetic anisotropy of [Ti2Cl9]−3

The theory of the kinetic exchange in a pair of orbitally degenerate ions developed by the authors [J. Phys. Chem. A 102, 200 (1998)] is applied to the case of face-shared bioctahedral dimer (overall D3h-symmetry). The effective kinetic exchange Hamiltonian is found for a 2T2–2T2 system taking into account all relevant transfer pathways and charge-transfer crystal field states. The influence of different transfer integrals involved in the kinetic exchange on the energy pattern and magnetic properties of the system is examined. The role of other related interactions (trigonal crystal field, spin–orbit coupling) is also discussed in detail. Using the pseudoangular momentum representation and the technique of the irreducible tensor operators of R3-group we give a general outlook on the nontrivial symmetry properties of the effective Hamiltonian for the D3h-pair, and on the magnetic anisotropy arising from the orbital interactions specific for the case of orbital degeneracy. The magnetic properties of the binuclear unit [Ti2Cl9]−3 in Cs3Ti2Cl9 are discussed with a special emphasis on the magnetic anisotropy experimentally observed in this system. The existing exchange models for [Ti2Cl9]−3 and the concept of the effective Hamiltonian are discussed in the context of the present [email protected] ; [email protected] ; [email protected] ; [email protected]

Double quantum dot with tunable coupling in an enhancement-mode silicon metal-oxide semiconductor device with lateral geometry

We present transport measurements of a tunable silicon metal-oxide-semiconductor double quantum dot device with lateral geometry. Experimentally extracted gate-to-dot capacitances show that the device is largely symmetric under the gate voltages applied. Intriguingly, these gate voltages themselves are not symmetric. Comparison with numerical simulations indicates that the applied gate voltages serve to offset an intrinsic asymmetry in the physical device. We also show a transition from a large single dot to two well isolated coupled dots, where the central gate of the device is used to controllably tune the interdot coupling.Comment: 4 pages, 3 figures, to be published in Applied Physics Letter

Wear model for describing the time dependence of the material degradation mechanisms of the AISI 316L in a NaCl solution

[EN] The tribo-electrochemical behavior of AISI 316L has been investigated under tribocorrosion conditions in a 3% NaCl solution and the material damage evolution with time has been analyzed. A numerical contact model based on a Boundary Element Method (BEM) has been developed in order to determine the contact pressure distribution and to quantify the worn material as a function of time. The time dependence of the tribological behavior of the material has been described. At the initial state, the high contact pressures generate a material flow causing an increase in the worn area. After around 300 cycles, the Archard wear model linearly describes the wear evolution with time. The proposed model describes the evolution with time of the wear profiles of the tested material and takes into account the plastic behavior of the material during the first cycles.This work has been funded by the Spanish Ministry of Economy and Competitiveness under the Ref. MAT2014-53764-C3-3-R and the Generalitat Valenciana under the PROMETEO program Ref. 2016/040.Dalmau-Borrás, A.; Roda Buch, A.; Rovira, A.; Navarro-Laboulais, J.; Igual Muñoz, AN. (2018). Wear model for describing the time dependence of the material degradation mechanisms of the AISI 316L in a NaCl solution. Wear. 394-395:166-175. https://doi.org/10.1016/j.wear.2017.10.015S166175394-39

Chemo-mechanical effects on the tribocorrosion behavior of titanium/ceramic dental implant pairs in artificial saliva

[EN] In this paper, the degradation mechanisms of the ceramic and the metal in Titanium/Zirconia pairs for biomedical applications were analyzed. To do that, an experimental set-up with well-controlled mechanical and chemical conditions was used based on a unidirectional ball-on-disk tribometer coupled to a potentiostat. Tribocorrosion tests were carried out in artificial saliva at different applied potentials, this is, different chemical conditions of the surface. Wear damage of the titanium/zirconia pair was influenced by the properties and the behavior of wear debris in the contact. Under passive conditions metallic and oxidized titanium particles (formed by the cyclic removal of the passive film and subsequent repassivation) were smeared and mechanically mixed within the contact forming compacted wear debris through which the loading was carried out. Properties and amount of oxidized titanium lead to low wear at low passive conditions (OCP) and higher wear at high passive conditions. Zirconia did not suffer any damage under all the studied conditions and oxidized titanium was transferred to the ball at anodic applied potentials.Authors would like to acknowledge the Generalitat Valenciana for the financial support under the PROMETEO/2016/040 and GV/2017/042 projects. A. Dalmau acknowledges the Generalitat Valenciana for her contract (APOSTD/2017/051).Dalmau-Borrás, A.; Roda Buch, A.; Rovira, A.; Navarro-Laboulais, J.; Igual Muñoz, AN. (2019). Chemo-mechanical effects on the tribocorrosion behavior of titanium/ceramic dental implant pairs in artificial saliva. Wear. 426-427:162-170. https://doi.org/10.1016/j.wear.2018.12.052162170426-42

Development of a stress-induced martensitic transformation criterion for a Cu-Al-Be polycrystalline shape memory alloy undergoing uniaxial tension

This study presents a criterion for predicting the martensitic variants (MVs) that appear during the stress-induced martensitic transformation (SIMT) in a polycrystalline sample of Cu 11.5% wt. Al 0.5% wt. Be under simple tension. Our criterion is based on crystallographic parameters, such as the crystal orientation and Schmid factor (SF). The displacement vector fields (DVFs) were obtained in the observation system by a mathematical model and were used to distort the boundary of a set of grains. From the DVF, the strain tensor for each grain was obtained, and the strain ratio (SR) in the observation system was calculated. Electron backscattering diffraction (EBSD) measurements were performed to determine the crystal orientation of the grains. The inverse SF was used to determine the in-plane stress transformation diagrams (STDs) for each studied grain. The combination of a balance criterion (BC) and STD provided a criterion that allowed us to predict the possible order of stress-induced MVs formed as a function of the crystal orientation and thermomechanical parameters of the shape memory alloy (SMA) with higher accuracy than when using the criteria separately. To validate our criteria, we tested other researchers published results. Our results were in agreement and were capable of predicting the stress-induced MVs in a polycrystalline SMA.The authors wish to thank the Coordinacion de estudios de posgrado (CEP)-UNAM, PAPIIT project number TI 02414 and Instituto de Tecnologia de Materiales-UPV for financial support. The authors are grateful to the Electron Microscopy Service of the UPV and especially to Manuel Josep Planes Insausti and Jose Luis Moya Lopez. The authors are grateful to Martin Estrada Arcos, Alberto Higuera Garcia, and Antonio Gonzalez Montaiio for their technical support.García Castillo, F.; Cortés Pérez, J.; Amigó Borrás, V.; Sánchez Arévalo, P.; Lara Rodríguez, G. (2015). Development of a stress-induced martensitic transformation criterion for a Cu-Al-Be polycrystalline shape memory alloy undergoing uniaxial tension. Acta Materialia. 97:131-145. https://doi.org/10.1016/j.actamat.2015.06.044S1311459