Simulation of many-qubit quantum computation with matrix product states

Matrix product states provide a natural entanglement basis to represent a quantum register and operate quantum gates on it. This scheme can be materialized to simulate a quantum adiabatic algorithm solving hard instances of a NP-Complete problem. Errors inherent to truncations of the exact action of interacting gates are controlled by the size of the matrices in the representation. The property of finding the right solution for an instance and the expected value of the energy are found to be remarkably robust against these errors. As a symbolic example, we simulate the algorithm solving a 100-qubit hard instance, that is, finding the correct product state out of ~ 10^30 possibilities. Accumulated statistics for up to 60 qubits point at a slow growth of the average minimum time to solve hard instances with highly-truncated simulations of adiabatic quantum evolution.Comment: 5 pages, 4 figures, final versio

The role of stellar radial motions in shaping galaxy surface brightness profiles

Aims. The physics driving features such as breaks observed in galaxy surface brightness (SB) profiles remains contentious. Here, we assess the importance of stellar radial motions in shaping their characteristics. Methods. We use the simulated Milky Way-mass cosmological discs from the Ramses Disc Environment Study (RaDES) to characterise the radial redistribution of stars in galaxies displaying type-I (pure exponentials), II (downbending), and III (upbending) SB profiles. We compare radial profiles of the mass fractions and the velocity dispersions of different sub-populations of stars according to their birth and current location. Results. Radial redistribution of stars is important in all galaxies regardless of their light profiles. Type-II breaks seem to be a consequence of the combined effects of outward-moving and accreted stars. The former produce shallower inner profiles (lack of stars in the inner disc) and accumulate material around the break radius and beyond, strengthening the break; the latter can weaken or even convert the break into a pure exponential. Further accretion from satellites can concentrate material in the outermost parts, leading to type-III breaks that can coexist with type-II breaks, but situated further out. Type-III galaxies would be the result of an important radial redistribution of material throughout the entire disc, as well as a concentration of accreted material in the outskirts. In addition, type-III galaxies display the most efficient radial redistribution and the largest number of accreted stars, followed by type-I and II systems, suggesting that type-I galaxies may be an intermediate case between types-II and III. In general, the velocity dispersion profiles of all galaxies tend to flatten or even increase around the locations where the breaks are found. The age and metallicity profiles are also affected, exhibiting different inner gradients depending on their SB profile, being steeper in the case of type-II systems (as found observationally). The steep type-II profiles might be inherent to their formation rather than acquired via radial redistribution

Effects of variable and constant temperatures on the embryonic development and survival of a new grape pest, xylotrechus arvicola (Coleoptera: Cerambycidae)

Xylotrechus arvicola Olivier (Coleoptera: Cerambycidae) has become a new expanding pest in grape (Vitis spp.) crops. To better improve control tactics, the consequences of 11 constant (12, 15, 18, 21, 24, 27, 30, 32, 34, 35 and 36°) and nine variable temperatures (with equal mean temperatures at each of the nine constant rates ranging from 15 to 35°) on survival and embryonic development were studied. The eggs were able to complete development at constant temperatures between 15 and 35°, with mortality rates at the extremes of the range of two and 81.5%, respectively. Using variable temperatures a mortality rate of 38.9% at a mean temperature of 15° and 99% at 35° was observed. The range of time for embryonic development was 29.5 d at 15° to 6 d at 32° at constant temperatures, and from 29.6 d at 15° to 7.2 d at 32° at variable temperatures. The goodness-of-fit of different development models was evaluated for the relationship between the development rate and temperature. The models that gave the best fit were the Logan type III for constant temperatures and The Briare for variable temperatures. Optimum temperatures were estimated to be from 31.7 to 32.9°. The models that best described embryo development under natural field conditions were the Logan type III model for constant temperatures (98.7% adjustment) and The Lactin model for variable temperatures (99.2% adjustment). Nonlinear models predicted faster development at constant temperatures and slower development at variable ones when compared with real field development, whereas the linear model always predicted faster development than what actually took place. © 2011 Entomological Society of America.The Spanish Institute for Food and Agricultural Sciences and Technologies (INIA) funded this research, project no. RTA04-117-C2.Peer Reviewe

The influence of parents on achievement orientation and motivation for sport of adolescent athletes with and whithout disabilities

The purpose was three-fold. First, to analyze the psychometric properties of scales used. Second, to test the relationship among athletes’ perceptions of parents’ goal orientation and their own goal orientation and intrinsic motivation. Third, to compare athletes with and without disabilities with respect to the infuence of parents on athletes’ achievement orientation and motivation for sport. Participants were 173 amateur athletes (80 with disabilities, 93 without disabilities). Structural equation models revealed that for the athletes with disabilities, task orientation and the perceptions of parents’ task orientation were related to athletes’ interest-enjoyment and effort-importance. For the athletes without disabilities, ego orientations showed a negative relationship to interest-enjoyment and a positive relation to tension-pressure, and task orientation was related to interest-enjoyment,perceived competence and effort-importance

Models teòrics explicatius de l'aprenentatge motor

En este artículo se repasan los principales modelos teóricos explicativos del aprendizaje motor. En un primer apartado se comentan las aportaciones propias de la psicología cognitiva y más concretamente del corriente del procesamiento de la información: la Teoría del bucle cerrado de Jack Adams y la Teoría del esquema de Richard Schmidt. Posteriormente, se exponen las críticas que han recibido estos modelos y, para hacerlo, se introducen las principales aportaciones que el científico ruso Nikolai Bernstein hizo al estudio del aprendizaje y el control motor. A partir de estas aportaciones, se introducen las formulaciones teóricas que, surgidas desde la perspectiva dinámica-ecológica, pretenden superar las limitaciones de los modelos cognitivos. Finalmente, se comparan las dos perspectivas y se sugieren algunas posibles vías de desarrollo futuro del campo que nos ocupa. _____________________________________________________________________________________________________________________________________________________________ Cet article permet à l’auteur de réviser les principaux modèles théoriques explicatifs de l’apprentissage moteur. Dans un premier chapitre, il commente les contributions propres de la psychologie cognitive et plus concrètement du courant du traitement de l’information: la théorie en boucle fermée de Jack Adams et la théorie du schéma de Richard Schmidt. Ensuite, il expose les critiques qu’ont reçues ces modèles et, pour ce faire, il introduit les principales contributions que le scientifique russe Nikolaï Bernstein a faites à l’étude de l’apprentissage et du contrôle moteur. À partir de ces contributions, il introduit les formulations théoriques, issues de la perspective dynamico-écologique, qui prétendent aller au-delà des limites des modèles cognitifs. Enfin, il compare les deux perspectives et suggèrent certaines voies possibles pour le développement à venir du domaine qui nous intéresse.En este artículo se repasan los principales modelos teóricos explicativos del aprendizaje motor. En un primer apartado se comentan las aportaciones propias de la psicología cognitiva y más concretamente del corriente del procesamiento de la información: la Teoría del bucle cerrado de Jack Adams y la Teoría del esquema de Richard Schmidt. Posteriormente, se exponen las críticas que han recibido estos modelos y, para hacerlo, se introducen las principales aportaciones que el científico ruso Nikolai Bernstein hizo al estudio del aprendizaje y el control motor. A partir de estas aportaciones, se introducen las formulaciones teóricas que, surgidas desde la perspectiva dinámica-ecológica, pretenden superar las limitaciones de los modelos cognitivos. Finalmente, se comparan las dos perspectivas y se sugieren algunas posibles vías de desarrollo futuro del campo que nos ocupa.In this article they go over the principle explanatory theoretical models of the learning motor. First of all they comment on the contributions made by cognitive psychology and more specifically of the ordinary processing of information: A Closed Loop Theory of Motor Control by Jack Adams and the Theory of the Plan by Richard Schmidt. Later, there is an explanation of the criticism that these models have received and, to do so, they introduce the principal contributions that the Russian scientist Nikolai Bernstein made with his study on learning and the control motor. From these contributions, they introduced the theoretical formulations with which, arisen from the dynamicecological perspective, they try to overcome the limitations of the cognitive models. Finally, they compare the two perspectives and suggest some possible channels of future development in the field of education

Optimisation of energy supply at off-grid healthcare facilities using Monte Carlo simulation

In this paper, we present a methodology for the optimisation of off-grid hybrid systems (photovoltaic-diesel-battery systems). A stochastic approach is developed by means of Monte Carlo simulation to consider the uncertainties of irradiation and load. The optimisation is economic; that is, we look for a system with a lower net present cost including installation, replacement of the components, operation and maintenance, etc. The most important variable that must be estimated is the batteries lifespan, which depends on the operating conditions (charge/discharge cycles, corrosion, state of charge, etc.). Previous works used classical methods for the estimation of batteries lifespan, which can be too optimistic in many cases, obtaining a net present cost of the system much lower than in reality. In this work, we include an advanced weighted Ah-throughput model for the lead-acid batteries, which is much more realistic. The optimisation methodology presented in this paper is applied in the optimisation of the electrical supply for an off-grid hospital located in Kalonge (Democratic Republic of the Congo). At the moment, the power supply relies on a diesel generator; batteries are used in order to ensure the basic supply of energy when the generator is unavailable (night hours). The optimisation includes the possibility of adding solar photovoltaic (PV) panels to improve the supply of electrical energy. The results show that optimal design could achieve a 28% reduction in the levelised cost of energy and a 54% reduction in the diesel fuel used in the generator, thereby reducing pollution. Furthermore, we discuss possible improvements to the telecommunications of the hospital

Evidence of ongoing radial migration in NGC 6754: Azimuthal variations of the gas properties

Understanding the nature of spiral structure in disk galaxies is one of the main, and still unsolved questions in galactic astronomy. However, theoretical works are proposing new testable predictions whose detection is becoming feasible with recent development in instrumentation. In particular, streaming motions along spiral arms are expected to induce azimuthal variations in the chemical composition of a galaxy at a given galactic radius. In this letter we analyse the gas content in NGC 6754 with VLT/MUSE data to characterise its 2D chemical composition and H$\alpha$ line-of-sight velocity distribution. We find that the trailing (leading) edge of the NGC 6754 spiral arms show signatures of tangentially-slower, radially-outward (tangentially-faster, radially-inward) streaming motions of metal-rich (poor) gas over a large range of radii. These results show direct evidence of gas radial migration for the first time. We compare our results with the gas behaviour in a $N$-body disk simulation showing spiral morphological features rotating with a similar speed as the gas at every radius, in good agreement with the observed trend. This indicates that the spiral arm features in NGC 6754 may be transient and rotate similarly as the gas does at a large range of radii.Comment: 8 pages, 4 figures, accepted for publication in ApJL 2016 September 2