Quantum tomography via equidistant states

We study the possibility of performing quantum state tomography via equidistant states. This class of states allows us to propose a non-symmetric informationally complete POVM based tomographic scheme. The scheme is defined for odd dimensions and involves an inversion which can be analytically carried out by Fourier transform

On quadratic Hom-Lie algebras with equivariant twist maps and their relationship with quadratic Lie algebras

Hom-Lie algebras having non-invertible and equivariant twist maps are studied. Central extensions of Hom-Lie algebras having these properties are obtained and shown how the same properties are preserved. Conditions are given so that the produced central extension has an invariant metric with respect to its Hom-Lie product making its twist map self-adjoint when the original Hom-Lie algebra has such a metric. This work is focused on algebras with these properties and we call them quadratic Hom-Lie algebras. It is shown how a quadratic Hom-Lie algebra gives rise to a quadratic Lie algebra and that the Lie algebra associated to the given Hom-Lie central extension is a Lie algebra central extension of it. It is also shown that if the 2-cocycle associated to the central extension is not a coboundary, there exists a non-abelian and non-associative algebra, the commutator of whose product is precisely the Hom-Lie product of the Hom-Lie central extension. Moreover, the algebra whose commutator realizes this Hom-Lie product is shown to be simple if the associated Lie algebra is nilpotent. Non-trivial examples are provided

Experimental scheme for unambiguous discrimination of linearly independent symmetric states

We propose an optimal discrimination scheme for a case of four linearly independent nonorthogonal symmetric quantum states, based on linear optics only. The probability of discrimination is in agreement with the optimal probability for unambiguous discrimination among N symmetric states [Phys. Lett. A \textbf{250}, 223 (1998)]. The experimental setup can be extended for the case of discrimination among $2^M$ nonorthogonal symmetric quantum states

Effect of morphology and hydrophobization of MoS2 microparticles on the stability of poly-α-olefins lubricants

International audienceThe use of MoS ⁠ 2 nanoparticles as additive to lubricating oils is restricted by their low stability in oily media, which limits their use despite the enormous benefits associated with their intrinsic properties in terms of reduction of friction and wear coefficients. In this context, we investigated the effect of morphologies (platelets vs spheres) and surface functionalization of nanoparticles on the stability of their suspensions in poly-α-olefins (PAO) with various viscosities, which are base oils used in wind turbines. The particles were characterized by XRD, FTIR, scanning electron microscopy, atomic force microscopy and dynamic light scattering, and the stability of the resultant formulations was followed by optical (non-contact) measurements. It was found that the dispersions had similar stability despite the larger size of platelet-like particles compared to spherical ones (1-5 μm vs 600-800 nm). The dispersibility could be increased through grafting of alkylsilane on the surface defects (the longer the alkyl chain, the more stable the formulation) and with the increase of the oil kinematic viscosity (from 34 to 1705 cps at 25 °C)

Efecto de la fertilización en la producción de materia seca y extracción de nutrientes en tres accesiones de lippia origanoides h.b.k.

An experiment under greenhouse conditions at the Universidad Nacional de Colombia- Palmira to evaluate the relationship among plant nutrition, levels of nutrient uptake and dry matter production of three accessions of Lippia origanoides (Patía, Cítrica and Típica), was carried out. Concentrations of foliar nutrients, absorption and extraction rates (of 5 elements N, P, K, Mg and Ca) and their relationship with the production of each accession were evaluated. A split plot design with 11 treatments and three replications was used. The experimental units consisted of a plant sowed in substrate (peat). Fertilization was done by fertigation using the modified Hoagland and Arnon nutrient solution. The Patía accession showed the maximum dry matter yield (292.0 ± 0.1 g plant-1) with the treatment 8 (Mg decreased), the Cítrica accession yielded 287.1 ± 0.1 g plant-1 with the treatment 9 (Mg increase) and finally Típica accession (255.2 ± 0.1 g plant-1) with the treatment 8. In terms of absorption of nutrients, potassium is the most required element (13.9 kg t-1), followed by calcium (7.9 kg t-1).En las casas de vegetación de la Universidad Nacional de Colombia sede Palmira (930 m.s.n.m. y 26 °C), se estudió la relación entre la nutrición de plantas de las accesiones Patía, Cítrica y Típica de Lippia origanoides H.B.K., los niveles de extracción de nutrientes y la producción y distribución de materia seca (MS). Para el efecto se determinaron las concentraciones de elementos foliares, los niveles de absorción y extracción de N, P, K, Mg y Ca y su relación con la producción de cada accesión. Se utilizó un diseño en parcelas divididas con once tratamientos y tres repeticiones, las unidades experimentales consistieron en una planta sembrada en sustrato (turba). Los elementos se aplicaron con ferti-riego utilizando solución nutritiva de Hoagland y Arnon modificada. Los resultados mostraron que la accesión Patía presentó los mayores rendimientos de MS (292.0 ± 0.1 g/planta) cuando la concentración original de Mg (49 mg/lt) en la solución cambió para 30 mg/lt; en la accesión Cítrica fueron más altos (287.1 ± 0.1 g/planta) con 72 mg/lt de Mg y en la accesión Típica el rendimiento fue mayor (255.2 ± 0.1 g/planta) con la aplicación de 30 mg/lt de Mg. En términos de absorción de nutrientes, el K fue el elemento más requerido (13.9 kg/t), seguido de Ca (7.9 kg/t)

Aplicación de autómatas celulares para la descripción de extremos de la precipitación

Ponencia presentada en: IV Congreso de la Asociación Española de Climatología "El Clima entre el Mar y la Montaña", celebrado en Santander del 2 al 5 de noviembre de 2004.[ES]El objetivo de este estudio es comprobar la utilidad de la técnica de Autómatas Celulares (CA) par describir la ocurrencia de extremos de precipitación. Las series temporales de precipitación presentan algunos grados de periodicidad o fluctuaciones debidas a variabilidad climática natural. Una vez filtradas estas componentes mediante técnicas espectrales, aplicamos el modelo propuesto de CA a la serie residual con el fin de caracterizar las rachas secas y húmedas. Este método va a simular dos estados para excesos de precipitación, el estado 0 se corresponde con precipitaciones inferiores al percentil 75, mientras que el estado 1 para las superiores al percentil 75. De forma análoga procedemos para caracterizar rachas de precipitación escasa, consideraremos estado 0 para precipitaciones superiores o igual al percentil 25 y estado 1 para precipitaciones inferiores a dicho percentil. El método lo aplicamos a datos mensuales de precipitación en Salamanca en el periodo 1949 a 2003. Los primeros resultados indican que se consigue aproximar en un 60% la ocurrencia de extremos de precipitación, lo cuál sería de gran interés por su aplicación en planificaciones agrícolas.[EN]The objective of this study is to show the utility of using Cellular Automata (CA) to describe the occurrence of the precipitation extremes. Since the precipitation time series contain some quasi-periodic fluctuations, it is required to filter these components before applying the CA model to characterize the dry and wet spells. The CA used to describe the wet spells consists of two states 0 and 1, which were established according to the threshold of 75 percentile. Similarly, to describe the dry spells we propose a CA with two states 0 and 1 for values higher and lower than 25 percentile respectively. The method is applied to monthly precipitation data of Salamanca (Spain) for the period 1949 to 2003. The first results indicate that the model can capture the occurrence of the precipitation extremes with an 60% of accuracy, therefore this characterization could be useful for agricultural planning.Este trabajo se ha realizado con la subvención del proyecto “Fundación Memoria de D. Manuel Solórzano Barruso” y del proyecto “REN2002-04584-CO-02/CLI” del MCYT