Pitfalls on evaluating pair exchange interactions for modelling molecule-based magnetism

Molecule-based magnetism is a solid-state property that results from the microscopic interaction between magnetic centres or radicals. The observed magnetic response is due to unpaired electrons whose coupling leads to a particular magnetic topology. Therefore, to understand the magnetic response of a given molecule-based magnet and reproduce the available experimental magnetic properties by means of statistical mechanics, one has to be able to determine the value of the JAB magnetic exchange coupling between radicals. The calculation of JAB is thus a key point for modelling molecule-based magnetism. In this Perspectives article, we will build upon our experience in modelling molecular magnetism to point out some pitfalls on evaluating JAB couplings. Special attention must be paid to the cluster models used to evaluate JAB, which should account for cooperative effects among JAB interactions and also consider the environment (counterions, hydrogen bonding) of the two radicals whose interaction has to be evaluated. It will be also necessary to assess whether a DFT-based or a wavefunction-based method is best to study a given radical. Finally, in addition to model and method, the JAB couplings have to be able to adapt to changes in the magnetic topology due to thermal fluctuations. Therefore, it is most important to appraise in which systems molecular dynamics simulations would be required. Given the large number of issues one must tackle when choosing the correct model and method to evaluate JAB interactions for modelling magnetic properties in molecule-based materials, the “human factor” is a must to cross-examine and challenge computations before trusting any result

Autonomous hybrid GPS/reactive navigation of an unmanned ground vehicle for precision viticulture-VINBOT

Yield forecasting can provide important benefits for wine industry in terms of quality and efficiency. Vineyard yield estimation can be obtained using several methods being the most widely used the method based on visual assessment and/or counting/weighing the yield components The increasing importance of yield forecast has lead to automated solutions for the data acquisition and allowed the first service robotics applications in viticulture. In this paper we aim to present the preliminary results obtained in the European research project VinBot: “Autonomous cloudcomputing vineyard robot to optimize yield management and wine quality”. The paper focuses in the robot navigation. Robot navigation for agriculture has been a continuous research topic in the last years. Even there is a wide number of RTK-DGPS and PPP based navigation solutions available for precision farming, navigation in vineyards has some particularities and can benefit from other navigation techniques. The high cost and in some cases other limitations as fix ratios (determined by baseline distances to base stations), or communication limitations in the field make alternative solutions desirable. In this paper, we present a hybrid reactive/GPS based navigation scheme tested successfully in vineyard navigation. The proposed solution makes use of a laser range finder and RGBD device to perform reactive row following and obstacle avoidance, while it can make use of other reactive behaviors or GPS waypoint navigation for changing from row to row or field to field, thus supporting different levels of automation. The paper includes also some experiences with recently introduced new generation low-cost RTK-DGPS devices, that in the coming years will enable the progressive introduction of viticulture robotsinfo:eu-repo/semantics/publishedVersio

Migration paths saturations in meta-epidemic systems

In this paper we consider a simple two-patch model in which a population affected by a disease can freely move. We assume that the capacity of the interconnected paths is limited, and thereby influencing the migration rates. Possible habitat disruptions due to human activities or natural events are accounted for. The demographic assumptions prevent the ecosystem to be wiped out, and the disease remains endemic in both populated patches at a stable equilibrium, but possibly also with an oscillatory behavior in the case of unidirectional migrations. Interestingly, if infected cannot migrate, it is possible that one patch becomes disease-free. This fact could be exploited to keep disease-free at least part of the population

Global observational diagnosis of soil moisture control on the land surface energy balance

An understanding of where and how strongly the surface energy budget is constrained by soil moisture is hindered by a lack of large-scale observations, and this contributes to uncertainty in climate models. Here we present a new approach combining satellite observations of land surface temperature and rainfall.We derive a Relative Warming Rate (RWR) diagnostic, which is a measure of how rapidly the land warms relative to the overlying atmosphere during 10 day dry spells. In our dry spell composites, 73% of the land surface between 60°S and 60°N warms faster than the atmosphere, indicating water-stressed conditions, and increases in sensible heat. Higher RWRs are found for shorter vegetation and bare soil than for tall, deep-rooted vegetation, due to differences in aerodynamic and hydrological properties. We show how the variation of RWR with antecedent rainfall helps to identify different evaporative regimes in the major nonpolar climate zones

Compilation and validation of SAR and optical data products for a complete and global map of inland/ocean water tailored to the climate modeling community

Accurate maps of surface water extent are of paramount importance for water management, satellite data processing and climate modeling. Several maps of water bodies based on remote sensing data have been released during the last decade. Nonetheless, none has a truly (90°N/90°S) global coverage while being thoroughly validated. This paper describes a global, spatially-complete (void-free) and accurate mask of inland/ocean water for the 2000–2012 period, built in the framework of the European Space Agency (ESA) Climate Change Initiative (CCI). This map results from the synergistic combination of multiple individual SAR and optical water body and auxiliary datasets. A key aspect of this work is the original and rigorous stratified random sampling designed for the quality assessment of binary classifications where one class is marginally distributed. Input and consolidated products were assessed qualitatively and quantitatively against a reference validation database of 2110 samples spread throughout the globe. Using all samples, overall accuracy was always very high among all products, between 98% and 100%. The CCI global map of open water bodies provided the best water class representation (F-score of 89%) compared to its constitutive inputs. When focusing on the challenging areas for water bodies’ mapping, such as shorelines, lakes and river banks, all products yielded substantially lower accuracy figures with overall accuracies ranging between 74% and 89%. The inland water area of the CCI global map of open water bodies was estimated to be 3.17 million km2 ± 0.24 million km2. The dataset is freely available through the ESA CCI Land Cover viewer

A comparative study using an autostereoscopic display with augmented and virtual reality

Advances in display devices are facilitating the integration of stereoscopic visualization in our daily lives. However, autostereoscopic visualization has not been extensively exploited. In this paper, we present a system that combines Augmented Reality (AR) and autostereoscopic visualization. We also present the first study that compares different aspects using an autostereoscopic display with AR and VR, in which 39 children from 8 to 10 years old participated. In our study, no statistically significant differences were found between AR and VR. However, the scores were very high in nearly all of the questions, and the children also scored the AR version higher in all cases. Moreover, the children explicitly preferred the AR version (81%). For the AR version, a strong and significant correlation was found between the use of the autostereoscopic screen in games and seeing the virtual object on the marker. For the VR version, two strong and significant correlations were found. The first correlation was between the ease of play and the use of the rotatory controller. The second correlation was between depth perception and the game global score. Therefore, the combinations of AR and VR with autostereoscopic visualization are possibilities for developing edutainment systems for childrenThis work was funded by the Spanish APRENDRA project (TIN2009-14319-C02). We would like to thank the following for their contributions: AIJU, the "Escola d'Estiu" and especially Ignacio Segui, Juan Cano, Miguelon Gimenez, and Javier Irimia. This work would not have been possible without their collaboration. The ALF3D project (TIN2009-14103-03) for the autostereoscopic display. Roberto Vivo, Rafa Gaitan, Severino Gonzalez, and M. Jose Vicent, for their help. The children's parents who signed the agreement to allow their children to participate in the study. The children who participated in the study. The ETSInf for letting us use its facilities during the testing phase.Arino, J.; Juan Lizandra, MC.; Gil Gómez, JA.; Mollá Vayá, RP. (2014). A comparative study using an autostereoscopic display with augmented and virtual reality. Behaviour and Information Technology. 33(6):646-655. https://doi.org/10.1080/0144929X.2013.815277S646655336Azuma, R. T. (1997). A Survey of Augmented Reality. Presence: Teleoperators and Virtual Environments, 6(4), 355-385. doi:10.1162/pres.1997.6.4.355Blum, T.et al. 2012. Mirracle: augmented reality in-situ visualization of human anatomy using a magic mirror.In: IEEE virtual reality workshops, 4–8 March 2012, Costa Mesa, CA, USA. Washington, DC: IEEE Computer Society, 169–170.Botden, S. M. B. I., Buzink, S. N., Schijven, M. P., & Jakimowicz, J. J. (2007). Augmented versus Virtual Reality Laparoscopic Simulation: What Is the Difference? World Journal of Surgery, 31(4), 764-772. doi:10.1007/s00268-006-0724-yChittaro, L., & Ranon, R. (2007). 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Analysis of symmetries in models of multi-strain infections

In mathematical studies of the dynamics of multi-strain diseases caused by antigenically diverse pathogens, there is a substantial interest in analytical insights. Using the example of a generic model of multi-strain diseases with cross-immunity between strains, we show that a significant understanding of the stability of steady states and possible dynamical behaviours can be achieved when the symmetry of interactions between strains is taken into account. Techniques of equivariant bifurcation theory allow one to identify the type of possible symmetry-breaking Hopf bifurcation, as well as to classify different periodic solutions in terms of their spatial and temporal symmetries. The approach is also illustrated on other models of multi-strain diseases, where the same methodology provides a systematic understanding of bifurcation scenarios and periodic behaviours. The results of the analysis are quite generic, and have wider implications for understanding the dynamics of a large class of models of multi-strain diseases