RoboTSP - A Fast Solution to the Robotic Task Sequencing Problem

In many industrial robotics applications, such as spot-welding, spray-painting or drilling, the robot is required to visit successively multiple targets. The robot travel time among the targets is a significant component of the overall execution time. This travel time is in turn greatly affected by the order of visit of the targets, and by the robot configurations used to reach each target. Therefore, it is crucial to optimize these two elements, a problem known in the literature as the Robotic Task Sequencing Problem (RTSP). Our contribution in this paper is two-fold. First, we propose a fast, near-optimal, algorithm to solve RTSP. The key to our approach is to exploit the classical distinction between task space and configuration space, which, surprisingly, has been so far overlooked in the RTSP literature. Second, we provide an open-source implementation of the above algorithm, which has been carefully benchmarked to yield an efficient, ready-to-use, software solution. We discuss the relationship between RTSP and other Traveling Salesman Problem (TSP) variants, such as the Generalized Traveling Salesman Problem (GTSP), and show experimentally that our method finds motion sequences of the same quality but using several orders of magnitude less computation time than existing approaches.Comment: 6 pages, 7 figures, 1 tabl

Determinants demogràfics i actitudinals dels comportaments davant de la pràctica d’activitat fisicoesportiva de temps lliure a la ciutat de l’Havana (Cuba). Identificació del perfil poblacional mitjançant les xarxes de Bayes

Aquest estudi s’ha centrat a conèixer els comportaments de pràctica fisicoesportiva dels pobladors de l’Havana més grans de 15 anys, tot analitzant les relacions i les associacions probabilístiques que poden produir-se amb les variables sociodemogràfiques (sexe, edat, nivell d’estudis i ocupació principal) i les actitudinals (interès per la pràctica, valoració de l’educació física rebuda i actitud dels pares davant d’aquesta pràctica en temps lliure). La investigació s’ha desenvolupat a través d’entrevistes personals mitjançant un qüestionari estandarditzat a una mostra de 1.144 subjectes; hom ha utilitzat el procediment de mostreig estratificat polietàpic amb afixació proporcional, amb un marge d’error mostral del ± 3 % i un nivell de confiança del 95,5 %. Els resultats han posat de manifest, d’una banda, l’increment de pràctica entre els ciutadans de l’Havana; sobre els comportaments de pràctica són determinants, tant les variables sociodemogràfiques com les actitudinals tingudes en compte i, d’altra banda, de la xarxa de Bayes es desprèn la incidència directa de les classes d’Educació Física rebuda sobre els comportaments de pràctica i l’interès cap a aquesta

Validez del Penn State Worry Questionnaire-11 en Colombia y equivalencia factorial a través de género y muestras clínicas y no clínicas

The Penn State Worry Questionnaire (PSWQ) is the gold standard measure of the unspecific worry that characterizes generalized anxiety disorder. This study aims to explore the validity of the PSWQ in Colombia and its measurement invariance across gender and clinical and nonclinical participants. An abbreviated, 11-item version of the PSWQ by Sandín, Chorot, Valiente, and Lostao (2009) was used because the negatively worded items have shown to be problematic for Spanish speakers. Additionally, research has suggested that the negatively worded items of the PSWQ lack of practical utility. The PSWQ-11 was administered to a total of 1045 participants, including a sample of nonclinical participants (N = 710) and a sample of clinical participants (N = 335). The internal consistency of the PSWQ-11 across samples was excellent. The one-factor model showed an acceptable fit to the data. Metric and scalar invariance were observed across gender and clinical and nonclinical samples. In conclusion, the PSWQ-11 seems to be a valid measure of GAD-related worry in Colombia, whereas data on factorial equivalence data warrant the comparison of scores across gender and clinical and nonclinical samples.El Penn State Worry Questionnaire (PSWQ) es la medida principal de la preocupación inespecífica que caracteriza al trastorno de ansiedad generalizada (TAG). Este estudio explora la validez del PSWQ en Colombia y su invarianza de medida entre género y participantes clínicos y no clínicos. Se utilizó la versión abreviada de 11 ítems de PSWQ propuesta por Sandín, Chorot, Valiente y Lostao (2009) porque los ítems redactados negativamente han mostrado ser problemáticos para los hispanohablantes. Adicionalmente, la investigación ha sugerido que los ítems redactados en negativa carecen de utilidad práctica. El PSWQ-11 se administró a un total de 1045 participantes, incluyendo una muestra de participantes no clínicos (N = 710) y una muestra de participantes clínicos (N = 335). La consistencia interna del PSWQ-11 a través de muestras fue excelente. El modelo de un factor mostró un ajuste aceptable a los datos. Se observó invarianza métrica y escalar a través de género y muestras clínicas y no clínicas. En conclusión, el PSWQ-11 parece ser una medida válida de la preocupación tipo TAG, mientras que los datos sobre equivalencia factorial permiten la comparación de puntuaciones a través de género y participantes clínicos y no clínicos

Temporal evolution of acid mine drainage (AMD) leachates from the abandoned tharsis mine (Iberian Pyrite Belt, Spain)

Acid mine drainage (AMD) due to the mining of sulfide deposits is one of the most important causes of water pollution worldwide. Remediation measures, especially in historical abandoned mines, require a deep knowledge of the geochemical characteristics of AMD effluents and metal fluxes, considering their high spatial and temporal evolution, and the existence of point and diffuse sources with a different response to rainfall events. This study investigates the temporal variations and hydrogeochemical processes affecting the composition of main AMD sources from the Tharsis mines (SW Spain), one of most important historical metal mining districts in the world. To address this, a fortnightly-monthly sampling was performed during two years in the main AMD sources and streams within the mine site covering different hydrological conditions. A seasonal pattern was observed linked to hydrological variations; higher pollutant concentrations were observed during the dry season (maximum values of 4,6 g/L of Al, 11,8 g/L of Fe, and 67 g/L of sulfate) and lower ones were observed during the rainy periods. Stream samples exhibited a negative correlation between electrical conductivity (EC) and flow, while positive values were observed in AMD sources, where groundwater fluxes were predominant. High flow also seems to be the main driver of Pb fluxes from AMD sources, as the concentration of Pb in waters increased notably during these events. The precipitation of secondary Fe minerals may limit the mobility of As and V, being retained in the proximity of mine sites. The concentration of Zn in waters seems to be controlled by the original grade in the metal deposit from which the waste is generated, together with the age of these wastes. The pollutant load delivered by the Tharsis mines to the surrounding water courses is very high; e.g., mean of 733 ton/yr of Al or 2757 ton/yr of Fe, deteriorating the streams and reservoirs downstream.This work was supported by the Spanish Ministry of Economic and Competitiveness through the projects CGL2016-78783-C2-1-R (SCYRE) and by H2020 European Institute of Innovation and Technology (EIT RawMaterials) through the projects Modular recovery process services for hydrometallurgy and water treatment (MORECOVERY). C.R Canovas thanks the Spanish Ministry of Science and Innovation for the Postdoctoral Fellowship granted under application reference RYC2019- 027949-I. F. Macias was funded by the R&D FEDER Andalucía 2014–2020 call through the project RENOVAME (FEDER; UHU-1255729). Funding for open access charge: Universidad de Huelva/CBU

Phosphogypsum weathering and implications for pollutant discharge into an estuary

Approximately 100 million tons of phosphogypsum were stockpiled onto marsh soils of the Tinto River estuary (Huelva, SW Spain). This study focuses on the hydraulic response of the phosphogypsum stack to the different weathering agents, as well as on the hydrochemical behavior of highly acidic and polluted effluents from its leaching during different hydrological conditions. To address these issues, a CTD-Diver was installed in a bore-hole within a phosphogypsum stack profile, which recorded the variations in the water-table of the stack, and edge outflows samples were collected around the perimeter of the stack during four sampling periods in different seasons. During dry periods, the water-table of the stack remains almost static and is controlled only by the tide oscillations. However, during rainy events this water-level rapidly increases up to 20 cm and subsequently decreases, defining peaks that coincide with the rainfalls. Having a hydraulic connection to the sea and groundwater flow in conduits, the phosphogypsum stack behaves as an anthropogenic karstic-coastal aquifer. Regarding the hydrochemical behavior of the edge outflows, the concentrations of most pollutants (e.g., PO4, Al, As, Cd or U) showed a slight decrease from the dry-warm to the rainy period. These leachates releases high concentrations of contaminants to the estuary, e.g., PO4, As and U (average values of 5000, 6.9 and 3.0 t/yr, respectively). The results obtained in this study could contribute to the development of effective treatment systems for leachates from phosphogypsum stack of Huelva and to minimize their impact on the surrounding estuarine environment.This work was supported by the Spanish Ministry of Economy and Competitiveness, the European Regional Development Fund and the University of Huelva under the research projects TRAMPA (MINECO; PID2020-119196RB-C21), VALOREY (MINECO; RTI 2018-101276-JI00) and EMFHA-SIST (FEDER; UHU-486 1253533). C.R C´anovas thanks the Spanish Ministry of Science and Innovation for the Postdoctoral Fellowship granted under application reference RYC2019- 027949-I. Funding for open access charge: Universidad de Huelva/ CBUA. We would also like to thank Dr. Huaming Guo (Editor-in-Chief) and two anonymous re-viewers for the support and comments that significantly improved the quality of the original paper

Aurophilicity as a cofactor in crystal engineering. Dicyanoaurate(I) anion as a building block in a novel Co(II)–Au(I) bimetallic assembly

A 2D grid-shaped cyanide-bridged Co(II)–Au(I) bimetallic coordination polymer, [Co(DMF)2{Au(CN)2}2], has been prepared from the [Au(CN)2]2 building block; sheets associate pair-wise by aurophilic interactions and the compound exhibits zeolite-like properties.Lloret Pastor, Francisco, [email protected]

Psychometric properties of the Valuing Questionnaire in a Spaniard sample and factorial equivalence with a Colombian sample

Background. The Valuing Questionnaire (VQ) is considered as one of the most psychometrically robust instruments to measure valued living according to the acceptance and commitment therapy model. It consists of 10 items that are responded to on a 7-point Likert-type scale and has two factors: Progression and Obstruction. The Spanish version of theVQshowed good psychometric properties in Colombian samples. However, there is no evidence of the psychometric properties of the VQ in Spaniard samples. This study aims to analyze the validity of the VQ in a large Spaniard sample and analyze the measurement invariance with a similar Colombian sample. Method. The VQ was administered to a Spaniard sample of 846 adult participants from general online population. Cronbach's alpha and McDonald's omega were computed to analyze the internal consistency of the VQ. The fit of the VQ's two-factor model was tested through a confirmatory factor analysis with a robust maximum likelihood (MLR) estimation method. Afterward, we analyzed the measurement invariance across countries and gender. Convergent construct validity was analyzed with a package of questionnaires that evaluated experiential avoidance (Acceptance and Action Questionnaire-II, AAQ-II), emotional symptoms (Depression Anxiety and Stress Scale-21, DASS-21), life satisfaction (Satisfaction with Life Scale, SWLS), and cognitive fusion (Cognitive Fusion Questionnaire, CFQ). Results. The internal consistency across samples was adequate (alphas and omegas were .85 for VQ-Progress and .84 for VQ-Obstruction). The two-factor model obtained a good fit to the data (RMSEA D 0.073, 90% CI [0.063, 0.083], CFI D 0.98, NNFI D 0.97, and SRMR D 0.053). The VQ showed strict invariance across countries and gender and showed theoretically coherent correlations with emotional symptoms, life satisfaction, experiential avoidance, and cognitive fusion. In conclusion, the Spanish version of the VQ demonstrated good psychometric properties in a large Spaniard sample

Metal bioaccumulation in spontaneously grown aquatic macrophytes in Fe-rich substrates of a passive treatment plant for acid mine drainage

Some plants may thrive in polluted environments, accumulating high concentrations of metal/loids in their organs. This study investigates for the first time the bioaccumulation and translocation of metal/loids in Typha domingensis spontaneously grown in extremely Fe-rich substrates (38–44% of Fe2O3) from different components of an acid mine drainage disperse alkaline substrate passive treatment. Most metal/loids were predominantly accumulated in the roots over the aerial parts of the plant, with concentrations of 0.66–9.5% of Fe, 0.02%–0.18% of Al, 55–2589 mg kg-1 of Mg, 51–116 mg kg-1 of Zn, 17–173 mg kg-1 of Cu, and 5.2–50 mg kg-1 of Pb. Bioconcentration factors were mostly below 1 for metal/loids in the studied aneas (e.g. 0.03–0.47 for Cu, 0.10–0.73 for Zn, 0.04–0.28 for As, 0.07–0.55 for Pb, 0.27–055 for Cd, 0.24–0.80 for Ni), which evidences that T. domingensis behaves as an excluder species in these substrates. Translocation factors were below 1 for most elements (e.g. 0.01–0.42 for As, 0.06–0.50 for Pb, 0.24–0.65 for Cd, and 0.10–0.56 for Sb), except for Mn, Ni and in some cases for Tl, Cu and Zn, which indicates limited transfer of metals between plant tissues. Mineralogical and geochemical substrate properties are pointed out as the main factors responsible for the lower bioconcentration and translocation of potentially toxic elements. In addition, the oxidizing conditions existent in the pore water-root system may also limit the mobility of metals from Fe oxides and hydroxysulfates, the main component of the substrate. The formation of a Fe plaque inside the roots may also limit the transfer of metals to the aerial parts. The spontaneous occurrence of T. domingensis in the substrates of the acid mine drainage passive treatments is an environmental indicator of the efficiency of the system and could be used as a complementary polishing step, given the strong tolerance of this plants to high concentrations of metal/loids.Funding for open access charge: Universidad de Huelva / CBUA M.D. Basallote thanks the Spanish Ministry of Science and Innovation for the Postdoctoral Fellowship granted under application reference IJC2018-035056-I. C.R C´anovas thanks the Spanish Ministry of Science and Innovation for the Postdoctoral Fellowship granted under application reference RYC2019-027949-I

Fatty acid and phenolic compound concentrations in eight different monovarietal virgin olive oils from Extremadura and the relationship with oxidative stability

Olive oils have been shown to be more resistant to oxidation than other vegetable fats, mainly due to their fatty acid (FA) profile which is rich in oleic acid and to their high content of antioxidants, principally phenols and tocopherols. This has situated virgin olive oils (VOOs) among the fats of high nutritional quality. However, it is important to stress that the oil’s commercial category (olive oil, virgin olive oil, extra-virgin olive oil), the variety of the source plant, and the extraction-conservation systems all decisively influence the concentration of these antioxidants and the oil’s shelf-life. The present work studied the fatty acid (FA) and phenolic composition and the oxidative stability (OS) of eight olive varieties grown in Extremadura (Arbequina, Cornicabra, Manzanilla Cacereña, Manzanilla de Sevilla, Morisca, Pico Limón, Picual, and Verdial de Badajoz), with the olives being harvested at different locations and dates. The Cornicabra, Picual, and Manzanilla Cacereña VOOs were found to have high oleic acid contents (>77.0%), while the VOOs of Morisca and Verdial de Badajoz had high linoleic acid contents (>14.5%). Regarding the phenol content, high values were found in the Cornicabra (633 mg. kg-1) and Morisca (550 mg.kg-1) VOOs, and low values in Arbequina (200 mg. kg-1). The OS was found to depend upon both the variety and the date of harvesting. It was higher in the Cornicabra and Picual oils (>55 h), and lower in those of Verdial de Badajoz (26.3 h), Arbequina (29.8 h), and Morisca (31.5 h). In relating phenols and FAs with the OS, it was observed that, while the latter, particularly the linoleic content (R = -0.710, p < 0.001, n = 135), constitute the most influential factors, the phenolic compounds, especially o-diphenols, are equally influential when the oils’ linoleic content is ≥12.5% (R = 0.674, p < 0.001, n = 47). The results show that VOOs’ resistance to oxidation depends not only on the FA or phenolic profile, but also on the interaction of these compounds within the same matrix.Trabajo financiado por: Acuerdo de investigación entre el Ministerio de Ciencia e Innovación y el Centro Tecnológico Agroalimentario de Extremadura Junta de Extremadura y Fondos FEDER. Ayuda GR15138peerReviewe