Compact set of invariants characterizing graph states of up to eight qubits

The set of entanglement measures proposed by Hein, Eisert, and Briegel for n-qubit graph states [Phys. Rev. A 69, 062311 (2004)] fails to distinguish between inequivalent classes under local Clifford operations if n > 6. On the other hand, the set of invariants proposed by van den Nest, Dehaene, and De Moor (VDD) [Phys. Rev. A 72, 014307 (2005)] distinguishes between inequivalent classes, but contains too many invariants (more than 2 10^{36} for n=7) to be practical. Here we solve the problem of deciding which entanglement class a graph state of n < 9 qubits belongs to by calculating some of the state's intrinsic properties. We show that four invariants related to those proposed by VDD are enough for distinguishing between all inequivalent classes with n < 9 qubits.Comment: REVTeX4, 9 pages, 1 figur

Diversity and distribution of blackflies (Diptera: Simuliidae) of the Tormes river basin (western Spain)

To enhance the partial knowledge on blackfly (Diptera: Simuliidae) fauna in Spain it is crucial to collect all the available data on this group to better understand their ecology and distribution over the years. This study presents data from samples collected along the Tormes river basin (western Spain) during the years 1988, 1989 and 1996 and then stored at the University of Salamanca. As a result of a research stay, a total of 19 species belonging to 3 genera (Prosimulium, Metacnephia and Simulium) and 5 Simulium subgenera (Boophthora, Eusimulium, Nevermannia, Simulium and Wilhelmia) were identified after examining 64% of the stored material, representing 35% of the species known from Spain. In addition, 14 species are reported for the first time in 3 provinces in the study area. Further sampling of blackflies is foreseen in the near future in order to check if the blackfly fauna composition determined in samples collected during the last two decades of the 20th century has changed. This aim gains in importance as a consequence of haematophagous species having been found, relevant for both public health and animal welfare, not only because of the discomfort caused by their bites but also because of their potential as vectors of disease-causing agents in animals and humans

Magnetic Nanoparticles as a Redispersing Additive in Magnetorheological Fluid

Unwanted agglomeration of micro particles in magnetorheological fluid is an important problem for many technological applications. Furthermore, the stability of this kind of fluid is also studied as an important property in many research papers. Prior to use, a redispersion of agglomerated or aggregated (connected by solid phase) particles is often necessary. The objective of this study is to evaluate the dispersibility effect of magnetic nanoparticles as a carrier, while keeping the magnetorheological (MR) effect as high as possible. A simple device based on the estimation of the penetration force of a standard needle is presented. The needle moves across the sample vertically with a constant velocity and it is attached to a scale which registers the force displaced by the needle during the dynamic test. The effect with and without other additives was also studied. Transmission electron microscopy (TEM) and Scanning Electron Microscopy (SEM) reveal a protective behavior of nanoparticles around the micro particles. We conclude that addition of magnetic nanoparticles improves the dispersibility characteristic compared with common dispersing additives without affecting the MR effect

Acercamiento a la situacion socioeconomica de las comunidades campesinas del Departamento de Sucre desde la perspectiva del Programa Yuquero

An overview is given of the situation of farm communities in the dept. of Sucre, Colombia, where a cassava drying program operates. The lack of integration of the developmental activities carried out by different institutions is evident, indicating the need for greater participation in district planning. Since a trend to monocrop cassava was observed, more attention should be paid to agricultural diversification. An animal feed industry using dried cassava should be installed. Several technical aspects of agricultural production are also discussed such as mechanization, intercropping, plant density, improved technology, and income. Recommendations are also given regarding the current underutilization of the machinery of the existing agroindustries, the improvement of sanitary conditions in the plants, and the enforcement of basic industrial security measures. Product quality control should be conducted, especially regarding MC. Conditions favoring a greater participation of members in farmer organizations should be sought, in addition to enhanced institutional support in the search for a more integrated approach to regional development. (CIAT)Se presenta una percepcion global de la situacion de las comunidades campesinas del Depto. de Sucre, Colombia, donde se desarrolla un programa de secado de la yuca. Se destaca la falta de integracion de las actividades de desarrollo realizadas por diversas instituciones, lo cual indica la necesidad de una mayor participacion en la planificacion distrital. Puesto que se observo una tendencia al monocultivo de la yuca, se debe prestar mas atencion a la diversificacion agricola. Se sugiere instalar una planta para producir alimentos para animales que aproveche la yuca seca. Se discuten, ademas, varios aspectos tecnicos de la produccion agricola como mecanizacion, cultivos asociados, densidad de siembra, tecnologia mejorada e ingresos. Tambien se presentan recomendaciones sobre la actual subutilizacion de la maquinaria en las agroindustrias existentes, el mejoramiento de los servicios higienicos en las plantas y la implementacion de medidas basicas de seguridad industrial. Se debe efectuar un control de calidad del producto, especialmente en cuanto a CH. Se deben buscar las condiciones para fomentar mayor participacion de los socios en las organizaciones, ademas de incrementar el apoyo institucional en busca de un enfoque mas integrado de desarrollo a nivel regional. (CIAT

Spin-parities of sub-threshold resonances in the 18^{18}F(p, α\alpha)15^{15}O reaction

The $^{18}$F(p, $\alpha$)$^{15}$O reaction is key to determining the $^{18}$F abundance in classical novae. However, the cross section for this reaction has large uncertainties at low energies largely caused by interference effects. Here, we resolve a longstanding issue with unknown spin-parities of sub-threshold states in $^{19}$Ne that reduces these uncertainties. The $^{20}$Ne($^3$He, $^4$He)$^{19}$Ne neutron pick-up reaction was used to populate $^{19}$Ne excited states, focusing on the energy region of astrophysical interest ($\approx$ 6 - 7 MeV). The experiment was performed at the Triangle Universities Nuclear Laboratory using the high resolution Enge split-pole magnetic spectrograph. Spins and parities were found for states in the astrophysical energy range. In particular, the state at 6.133 MeV (E$_{r}^{\text{c.m.}} = -278$ keV) was found to have spin and parity of $3/2^+$ and we confirm the existence of an unresolved doublet close to 6.288 MeV (E$_{r}^{\text{c.m.}} = -120$ keV) with J$^{\pi}$ = $1/2^+$ and a high-spin state. Using these results, we demonstrate a significant factor of two decrease in the reaction rate uncertainties at nova temperatures.Comment: 15 pages, 6 figures, accepted in Phys. Rev. C. Corrected typos and reference

Beta-decay of nuclei around Se-90. Search for signatures of a N=56 sub-shell closure relevant the r-process

Nuclear structure plays a significant role on the rapid neutron capture process (r-process) since shapes evolve with the emergence of shells and sub-shells. There was some indication in neighboring nuclei that we might find examples of a new N=56 sub-shell, which may give rise to a doubly magic Se-90 nucleus. Beta-decay half lives of nuclei around Se-90 have been measured to determine if this nucleus has in fact a doubly-magic character. The fragmentation of Xe-136 beam at the National Superconducting Cyclotron Laboratory at Michigan State University was used to create a cocktail of nuclei in the A=90 region. We have measured the half lives of twenty-two nuclei near the r-process path in the A=90 region. The half lives of As-88 and Se-90 have been measured for the first time. The values were compared with theoretical predictions in the search for nuclear-deformation signatures of a N=56 sub-shell, and its possible role in the emergence of a potential doubly-magic Se-90. The impact of such hypothesis on the synthesis of heavy nuclei, particularly in the production of Sr, Y and Zr elements was investigated with a weak r-process network. The new half lives agree with results obtained from a standard global QRPA model used in r-process calculations, indicating that Se-90 has a quadrupole shape incompatible with a closed N=56 sub-shell in this region. The impact of the measured Se-90 half-life in comparison with a former theoretical predication associated with a spherical half-life on the weak-r-process is shown to be strong

Propuesta metodológica para la evaluación de proyectos en cinco pasos

Objective: To carry out a methodological proposal for the evaluation of projects in five steps, which allows the procedure to be developed in a practical, easy, fast and orderly manner, generating understanding, effectiveness and efficiency in the analysis and confidence in the results obtained. Design / methodology / approach: It is based on the analytical-deductive cost-benefit ratio and the extrapolation method. The problem was identified and the five steps for project evaluation were structured. Results: The methodology for the evaluation of projects in five steps is proposed. Limitations / implications: There is limited knowledge of the analysis process translated into a disarticulation of the development of the procedure and distrust of the results obtained. It is because the designer is not a financial specialist and lacks theoretical support and methodological focus on the subject. Findings / Conclusions: This methodological proposal allows the development of the procedure in a practical, easy, fast and orderly manner, generating understanding, effectiveness and efficiency in the analysis and confidence in the results obtained for the decision making in the instrumentation of the Projects. It does have theoretical-practical utility and strengthens the theory of project evaluation.Objetivo: Realizar una propuesta metodológica para la evaluación de proyectos en cinco pasos, que permita desarrollar el procedimiento de forma práctica, fácil, rápida y ordenada, generando comprensión, eficacia y eficiencia en el análisis y confianza en los resultados obtenidos. Diseño/metodología/aproximación: Se basa en el método analítico-deductivo relación beneficio-costo y el método de extrapolación. Se identificó el problema y se estructuró los cinco pasos para la evaluación de proyectos. Resultados: Se propone la metodología para la evaluación de proyectos en cinco pasos. Limitaciones / implicaciones: Existe un limitado conocimiento del proceso de análisis traducido en una desarticulación del desarrollo del procedimiento y desconfianza en los resultados obtenidos. Se debe a que el proyectista no es especialista financiero y carece de sustento teórico y enfoque metodológico en el tema. Hallazgos / conclusiones: La propuesta metodológica permite llevar a cabo el desarrollo del procedimiento de forma práctica, fácil, rápida y ordenada, generando comprensión, eficacia y eficiencia en el análisis y confianza en los resultados obtenidos para la toma de decisiones en la instrumentación de los proyectos. Sí tiene utilidad teórica–práctica y fortalece la teoría de evaluación de proyectos

White light emitting silsesquioxane based materials: The importance of a ligand with rigid and directional arms

The synthesis of a novel polyhedral oligomeric silsesquioxane functionalized with eight rigid and directional terpyridine-based arms (Ter-POSS) was successfully achieved via a Sonogashira reaction. The POSS based ligand was extensively characterized using different techniques including 1H, 13C and 29Si NMR as well as UV-Vis and fluorescence spectroscopies. The assembly of these nano-caged units in the presence of different transition metal ions (Fe2+, Zn2+ and Cu2+) as well as of a cation from the lanthanides (Eu3+) was investigated using absorption and emission spectroscopies. The final materials display an evident emission in different regions of the visible spectrum as a function of the cation employed. Additional insights into the structural organization of Ter-POSS in the presence of metal cations were obtained via molecular mechanics and molecular dynamics simulations. The polymeric material resulting from the complexation with europium displays a white light emission ascribed to the presence of combined contributions from the blue, green and red regions. The final self-assembled organizations display an increased quantum yield with the highest value (29.6%) obtained in the presence of Zn2+. Moreover, the white-light emitting europium-based nanostructure exhibits one of the highest quantum yields reported in the literature for similar solids