On plane subgraphs of complete topological drawings

Topological drawings are representations of graphs in the plane, where vertices are represented by points, and edges by simple curves connecting the points. A drawing is simple if two edges intersect at most in a single point, either at a common endpoint or at a proper crossing. In this paper we study properties of maximal plane subgraphs of simple drawings Dnof the complete graph Knon n vertices. Our main structural result is that maximal plane subgraphs are 2-connected and what we call essentially 3-edge-connected. Besides, any maximal plane subgraph contains at least [3n/2] edges. We also address the problem of obtaining a plane subgraph of Dnwith the maximum number of edges, proving that this problem is NP-complete. However, given a plane spanning connected subgraph of Dn, a maximum plane augmentation of this subgraph can be found in O(n3) time. As a side result, we also show that the problem of finding a largest compatible plane straight-line graph of two labeled point sets is NP-complete. © 2021 Society of Mathematicians, Physicists and Astronomers of Slovenia. All rights reserved

A game theory-based approach for modeling autonomous vehicle behavior in congested, urban lane-changing scenarios

Autonomous vehicles are expected to display human-like behavior, at least to the extent that their decisions can be intuitively understood by other road users. If this is not the case, the coexistence of manual and autonomous vehicles in a mixed environment might affect road user interactions negatively and might jeopardize road safety. To this end, it is highly important to design algorithms that are capable of analyzing human decision-making processes and of reproducing them. In this context, lane-change maneuvers have been studied extensively. However, not all potential scenarios have been considered, since most works have focused on highway rather than urban scenarios. We contribute to the field of research by investigating a particular urban traffic scenario in which an autonomous vehicle needs to determine the level of cooperation of the vehicles in the adjacent lane in order to proceed with a lane change. To this end, we present a game theory-based decision-making model for lane changing in congested urban intersections. The model takes as input driving-related parameters related to vehicles in the intersection before they come to a complete stop. We validated the model by relying on the Co-AutoSim simulator. We compared the prediction model outcomes with actual participant decisions, i.e., whether they allowed the autonomous vehicle to drive in front of them. The results are promising, with the prediction accuracy being 100% in all of the cases in which the participants allowed the lane change and 83.3% in the other cases. The false predictions were due to delays in resuming driving after the traffic light turned green. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.This work was supported by the Austrian Ministry for Climate Action, Environment, Energy, Mobility, Innovation, and Technology (BMK) Endowed Professorship for Sustainable Transport Logistics 4.0., IAV France S.A.S.U., IAV GmbH, Austrian Post AG, and the UAS Technikum Wien. It was additionally supported by the Zero Emission Roll-Out?Cold Chain Distribution_877493

Depletion of the heaviest stable N isotope is associated with NH4+/NH3 toxicity in NH4+-fed plants

Open Access article - can be viewed online without a subscription at: http://dx.doi.org/doi:10.1186/1471-2229-11-83Background: In plants, nitrate (NO3 -) nutrition gives rise to a natural N isotopic signature (δ15N), which correlates with the δ15N of the N source. However, little is known about the relationship between the δ15N of the N source and the 14N/15N fractionation in plants under ammonium (NH4 +) nutrition. When NH4 + is the major N source, the two forms, NH4 + and NH3, are present in the nutrient solution. There is a 1.025 thermodynamic isotope effect between NH3 (g) and NH4 + (aq) which drives to a different δ15N. Nine plant species with different NH4 +-sensitivities were cultured hydroponically with NO3 - or NH4 + as the sole N sources, and plant growth and δ15N were determined. Short-term NH4 +/NH3 uptake experiments at pH 6.0 and 9.0 (which favours NH3 form) were carried out in order to support and substantiate our hypothesis. N source fractionation throughout the whole plant was interpreted on the basis of the relative transport of NH4 + and NH3. Results: Several NO3 --fed plants were consistently enriched in 15N, whereas plants under NH4 + nutrition were depleted of 15N. It was shown that more sensitive plants to NH4 + toxicity were the most depleted in 15N. In parallel, N-deficient pea and spinach plants fed with 15NH4 + showed an increased level of NH3 uptake at alkaline pH that was related to the 15N depletion of the plant. Tolerant to NH4 + pea plants or sensitive spinach plants showed similar trend on 15N depletion while slight differences in the time kinetics were observed during the initial stages. The use of RbNO3 as control discarded that the differences observed arise from pH detrimental effects. Conclusions: This article proposes that the negative values of δ15N in NH4 +-fed plants are originated from NH3 uptake by plants. Moreover, this depletion of the heavier N isotope is proportional to the NH4 +/NH3 toxicity in plants species. Therefore, we hypothesise that the low affinity transport system for NH4 + may have two components: one that transports N in the molecular form and is associated with fractionation and another that transports N in the ionic form and is not associated with fractionatio

Depletion of the heaviest stable N isotope is associated with NH4+/NH3 toxicity in NH4+-fed plants

Background: In plants, nitrate (NO3-) nutrition gives rise to a natural N isotopic signature (δ15N), which correlates with the δ15N of the N source. However, little is known about the relationship between the δ15N of the N source and the 14N/15N fractionation in plants under ammonium (NH4+) nutrition. When NH4 + is the major N source, the two forms, NH4 + and NH3, are present in the nutrient solution. There is a 1.025 thermodynamic isotope effect between NH3 (g) and NH4 + (aq) which drives to a different δ15N. Nine plant species with different NH4 +-sensitivities were cultured hydroponically with NO3 - or NH4 + as the sole N sources, and plant growth and δ15N were determined. Short-term NH4 +/NH3 uptake experiments at pH 6.0 and 9.0 (which favours NH3 form) were carried out in order to support and substantiate our hypothesis. N source fractionation throughout the whole plant was interpreted on the basis of the relative transport of NH4 + and NH3. Results: Several NO3 --fed plants were consistently enriched in 15N, whereas plants under NH4 + nutrition were depleted of 15N. It was shown that more sensitive plants to NH4 + toxicity were the most depleted in 15N. In parallel, N-deficient pea and spinach plants fed with 15NH4 + showed an increased level of NH3 uptake at alkaline pH that was related to the 15N depletion of the plant. Tolerant to NH4 + pea plants or sensitive spinach plants showed similar trend on 15N depletion while slight differences in the time kinetics were observed during the initial stages. The use of RbNO3 as control discarded that the differences observed arise from pH detrimental effects. Conclusions: This article proposes that the negative values of δ15N in NH4 +-fed plants are originated from NH3 uptake by plants. Moreover, this depletion of the heavier N isotope is proportional to the NH4 +/NH3 toxicity in plants species. Therefore, we hypothesise that the low affinity transport system for NH4 + may have two components: one that transports N in the molecular form and is associated with fractionation and another that transports N in the ionic form and is not associated with fractionation.This work was supported by the Spanish MICIIN (grant nos. AGL2006-12792-CO2- 01 and 02 and AGL2009- 13339-CO2-01 and 02 [to P.A.-T. and C.G.M.] and AGL2007-64432/AGR [to J.F.M.]), by the Portuguese FCT (PTDC/BIA- BEC/ 099323/2008) and by the Basque Government IT526-10

Movilidad Ip: macromovilidad, micromovilidad, calidad de servicio y seguridad

a actual tendencia hacia la provisión de conectvidad ubícua, independientemente del lugar, instante, aplicación utilizada, o tecnología de acceso ha contrbuÍdo a acuñar la expresión, "Always Best Connected" (ABC), para describir este entorno. Un requisito fundamental a cumplir hacia este objectivo consiste en ofrecer mecanismos de soporte a la movilidad de usuarios y/o terminales. En el presente artículo se revisan algunas de las soluciones para ofrecer movilidad en la capa de red, así como los puntos a salvar hacia ese objetivo, como son la calidad de servicio y la seguridad. Ambos puntos generan interesantes temas de investigación debido a la variabilidad de las condiciones asociadas a un entorno móvil, y al potencial aumento de las amenazas de seguridad.Postprint (published version

Movilidad Ip: macromovilidad, micromovilidad, calidad de servicio y seguridad

a actual tendencia hacia la provisión de conectvidad ubícua, independientemente del lugar, instante, aplicación utilizada, o tecnología de acceso ha contrbuÍdo a acuñar la expresión, "Always Best Connected" (ABC), para describir este entorno. Un requisito fundamental a cumplir hacia este objectivo consiste en ofrecer mecanismos de soporte a la movilidad de usuarios y/o terminales. En el presente artículo se revisan algunas de las soluciones para ofrecer movilidad en la capa de red, así como los puntos a salvar hacia ese objetivo, como son la calidad de servicio y la seguridad. Ambos puntos generan interesantes temas de investigación debido a la variabilidad de las condiciones asociadas a un entorno móvil, y al potencial aumento de las amenazas de seguridad

Movilidad Ip: macromovilidad, micromovilidad, calidad de servicio y seguridad

a actual tendencia hacia la provisión de conectvidad ubícua, independientemente del lugar, instante, aplicación utilizada, o tecnología de acceso ha contrbuÍdo a acuñar la expresión, "Always Best Connected" (ABC), para describir este entorno. Un requisito fundamental a cumplir hacia este objectivo consiste en ofrecer mecanismos de soporte a la movilidad de usuarios y/o terminales. En el presente artículo se revisan algunas de las soluciones para ofrecer movilidad en la capa de red, así como los puntos a salvar hacia ese objetivo, como son la calidad de servicio y la seguridad. Ambos puntos generan interesantes temas de investigación debido a la variabilidad de las condiciones asociadas a un entorno móvil, y al potencial aumento de las amenazas de seguridad