Optimización del diseño de las actuaciones y de la planta propulsora del INTA-ALO para la minimización del consumo energético

El objetivo de este trabajo es el estudio y optimización de las actuaciones y la planta propulsora de una aeronave con planta de potencia eléctrica. El avión estudiado es el INTA ALO, avión de reconocimiento y vigilancia en tiempo real con capacidad de recolección de imágenes en el espectro visible y de infrarrojos. La misión estudiada por su parte, es la que dicho avión desarrolla en el centro de investigación del Arenosillo. En el desarrollo del trabajo se ha estudiado la configuración inicial de la aeronave, obteniendo los consumos de potencia y energía. Posteriormente se ha desarrollado el proceso de optimización, identificando las posibilidades de mejora a introducir en la nueva configuración. Una vez seleccionada la configuración final, se han vuelto a calcular los consumos de potencia y energía para la misma, comparando estos con los resultados iniciales, verificándose así las mejoras introducidas por las modificaciones.The objective of this work is the study and optimization of the actions and the propulsion plant of an aircraft with electric power plant. The aircraft studied is the INTA ALO, a real-time reconnaissance and surveillance aircraft with image collection capacity in the visible and infrared spectrum. The mission studied, on the other hand, is the one that this aircraft develops in the Arenosillo research center. In the development of the work, the initial configuration of the aircraft has been studied, obtaining the power and energy consumption. Subsequently, the optimization process has been developed, identifying the possibilities of improvement to be introduced in the new configuration. Once the final configuration has been selected, the power and energy consumption for it has been recalculated, comparing these with the initial results, thus verifying the improvements introduced by the modifications.Universidad de Sevilla. Grado en Ingeniería Aeroespacia

Energy-based stochastic resetting can avoid noise-enhanced stability

The theory of stochastic resetting asserts that restarting a stochastic process can expedite its completion. In this paper, we study the escape process of a Brownian particle in an open Hamiltonian system that suffers noise-enhanced stability. This phenomenon implies that under specific noise amplitudes the escape process is delayed. Here, we propose a new protocol for stochastic resetting that can avoid the noise-enhanced stability effect. In our approach, instead of resetting the trajectories at certain time intervals, a trajectory is reset when a predefined energy threshold is reached. The trajectories that delay the escape process are the ones that lower their energy due to the stochastic fluctuations. Our resetting approach leverages this fact and avoids long transients by resetting trajectories before they reach low energy levels. Finally, we show that the chaotic dynamics (i.e., the sensitive dependence on initial conditions) catalyzes the effectiveness of the resetting strategy

Rate and memory effects in bifurcation-induced tipping

A variation in the environment of a system, such as the temperature, the concentration of a chemical solution or the appearance of a magnetic field, may lead to a drift in one of the parameters. If the parameter crosses a bifurcation point, the system can tip from one attractor to another (bifurcation-induced tipping). Typically, this stability exchange occurs at a parameter value beyond the bifurcation value. This is what we call here the stability exchange shift. We study systematically how the shift is affected by the initial parameter value and its change rate. To that end, we present numerical and analytical results for different types of bifurcations and different paradigmatic systems. Finally, we deduce the scaling laws governing this phenomenon. We show that increasing the change rate and starting the drift further from the bifurcation can delay the tipping process. Furthermore, if the change rate is sufficiently small, the shift becomes independent of the initial condition (no memory) and the shift tends to zero as the square root of the change rate. Thus, the bifurcation diagram for the system with fixed parameters is recovered

A toggle-switch and a feed-forward loop engage in the control of the Drosophila retinal determination gene network

Dipterans show a striking range of eye sizes, shapes, and functional specializations. Their eye is of the compound type, the most frequent eye architecture in nature. The development of this compound eye has been most studied in Drosophila melanogaster. The early development of the Drosophila eye is under the control of a gene regulatory network of transcription factors and signaling molecules called the retinal determination gene network (RDGN). Nodes in this network have been found to be involved not only in the development of different eye types in invertebrates and vertebrates, but also of other organs. Here we have analyzed the network properties in detail. First, we have generated quantitative expression profiles for a number of the key RDGN transcription factors, at a single-cell resolution. With these profiles, and applying a correlation analysis, we revisited several of the links in the RDGN. Our study uncovers a new link, that we confirm experimentally, between the transcription factors Hth/Meis1 and Optix/Six3 and indicates that, at least during the period of eye differentiation, positive feedback regulation from Eya and Dac on the Pax6 gene Ey is not operating. From this revised RDGN we derive a simplified gene network that we model mathematically. This network integrates three basic motifs: a coherent feedforward loop, a toggle-switch and a positive autoregulation which, together with the input from the Dpp/BMP2 signaling molecule, recapitulate the gene expression profiles obtained experimentally, while ensuring a robust transition from progenitor cells into retinal precursors.This work was funded by MINECO and the Agencia Estatal de Investigacion (AEI) of Spain, co-financed by FEDER funds (EU) through grants BFU2012-34324 and BFU2015-66040-P to FC, MDM-2016-0687 in which FC is participant researcher, and TIN2017-89842 P in which MCL is participant researcher

A Toggle-Switch and a Feed-Forward Loop Engage in the Control of the Drosophila Retinal Determination Gene Network

Dipterans show a striking range of eye sizes, shapes, and functional specializations. Their eye is of the compound type, the most frequent eye architecture in nature. The development of this compound eye has been most studied in Drosophila melanogaster. The early development of the Drosophila eye is under the control of a gene regulatory network of transcription factors and signaling molecules called the retinal determination gene network (RDGN). Nodes in this network have been found to be involved not only in the development of different eye types in invertebrates and vertebrates, but also of other organs. Here we have analyzed the network properties in detail. First, we have generated quantitative expression profiles for a number of the key RDGN transcription factors, at a single-cell resolution. With these profiles, and applying a correlation analysis, we revisited several of the links in the RDGN. Our study uncovers a new link, that we confirm experimentally, between the transcription factors Hth/Meis1 and Optix/Six3 and indicates that, at least during the period of eye differentiation, positive feedback regulation from Eya and Dac on the Pax6 gene Ey is not operating. From this revised RDGN we derive a simplified gene network that we model mathematically. This network integrates three basic motifs: a coherent feedforward loop, a toggle-switch and a positive autoregulation which, together with the input from the Dpp/BMP2 signaling molecule, recapitulate the gene expression profiles obtained experimentally, while ensuring a robust transition from progenitor cells into retinal precursors.MINECOFEDER (BFU2012-34324, BFU2015-66040-P)Agencia Estatal de Investigacion (AEI) of Spai

Age-Dependent Association between Low Frequency of CD27/CD28 Expression on pp65 CD8+ T Cells and Cytomegalovirus Replication after Transplantation

In this cross-sectional study of 42 solid organ transplant recipients, the association of human cytomegalovirus (HCMV) replication and age with the phenotype of the HCMV-specific CD8+ T cells was analyzed by using the CMV pp65 HLA-A*0201 pentamer. A correlation between the proportion of CD28− HCMV-specific CD8+ T cells and age was observed in patients without HCMV replication (r = 0.50; P = 0.02) but not in patients with HCMV replication (r = −0.05; P = 0.83), a finding which differs from that observed for total CD8+ T cells. Within the group of patients younger than 50 years of age, patients with HCVM replication after transplantation had higher percentages of CD28− HCMV-specific CD8+ T cells (85.6 compared with 58.7% for patients without HCMV replication; P = 0.004) and CD27− HCMV-specific CD8+ T cells (90.7 compared with 68.8% for patients without HCMV replication; P = 0.03). However, in patients older than age 50 years, a high frequency of these two subpopulations was observed in patients both with and without previous HCMV replication (for CD28− HCMV-specific CD8+ T cells, 84.4 and 80.9%, respectively [P = 0.39]; for CD27− HCMV-specific CD8+ T cells 86.6 and 81.5%, respectively [P = 0.16]). In conclusion, the present study shows that in the group of recipients younger than age 50 years, HCMV replication after transplantation is associated with a high percentage of CD27− and CD28− HCMV-specific CD8+ T cells. These results suggest that the increased percentage of CD27− or CD28− HCMV-specific subsets can be considered a biomarker of HCMV replication in solid organ transplant recipients younger than age 50 years but not in older patients. Further studies are necessary to define the significance of these changes in HCMV-associated clinical complications posttransplantation

Pretransplant CMV-Specific T-Cell Immunity But Not Dose of Antithymocyte Globulin Is Associated With Recovery of Specific Immunity After Kidney Transplantation

Background This is a prospective, multicenter, observational study in cytomegalovirus (CMV)-seropositive kidney transplant recipients with pretransplant CMV-specific cell-mediated immunity (CMV-CMI) receiving antithymocyte globulin (ATG). We aimed to investigate posttransplant CMV-CMI over time and the impact of the dose-dependent ATG. Methods CMV-CMI was assessed at days +30, +45, +60, and +90 after transplantation with the QuantiFERON-CMV assay. A reactive result (interferon-γ [IFN-γ] ≥ 0.2 IU/mL) indicated a positive CMV-CMI. Results A total of 78 positive CMV-CMI patients were enrolled in the study, of which 59.5% had a positive CMV-CMI at day +30 and 82.7% at day +90. Multivariate logistic regression analysis showed that ATG dose was not associated with positive CMV-CMI at any point. However, pretransplant IFN-γ level (>12 IU/mL vs ≤12 IU/mL) was associated with positive CMV-CMI at day +30 (odds ratio, 12.9; 95% confidence interval, 3.1–53.3; P < .001). In addition, all the patients who did not recover CMV-CMI at day +90 had a pretransplant IFN-γ level ≤12 IU/mL. Conclusions More than half of CMV-seropositive kidney transplant recipients receiving ATG recover (or maintain) CMV-CMI by the first month after transplantation. The pretransplant IFN-γ level, but not the ATG dose, shows a strong association with the kinetics of this recovery