69 research outputs found
Experimental investigation of rear flexible flaps interacting with the wake dynamics behind a squareback Ahmed body
We have conducted an experimental study on the use of rear flexible vertical flaps as adaptive solutions to reduce the drag of a squareback Ahmed body, and on the fluid–structure interaction mechanisms at the turbulent wake. To that aim, wind tunnel experiments were conducted to compare the performance of various configurations including the baseline body, the body with rigid flaps and with flexible flaps. These configurations were tested under different aligned and cross-flow conditions. The results reveal that the flexible adaptive devices effectively reduce the drag within for low values of the dimensionless stiffness quantified through the Cauchy number, ����. Thus, the two-dimensional deformation of the flexible flaps, which undergo progressive inwards reconfiguration (with an averaged tip deflection angle of �� ≃ 4◦), reduces the bluffness of the flow separation at the body base, thus shrinking the recirculation region. This reconfiguration leads to increased base pressure, resulting into a 8.3% decrease in the global drag, ����, under aligned conditions. Similar drag reductions are observed under yawed conditions. Two regimes are identified in terms of the coupled fluid–structure dynamics. For low ����, the passive reconfiguration of the flaps include small amplitude, periodic oscillations corresponding to the first free deformation mode of a cantilevered beam. Alongside these weak oscillations, the flaps are deformed guided by the changes in the value of the horizontal base pressure gradient, depicting bi-stable behavior which is caused by the synchronization between the Reflectional Symmetry Breaking (RSB) mode, typically present in the wake of three-dimensional bluff bodies, and the flaps deformation. For higher values of ����, the flexible flaps deflect inwardly by about �� ≃ 20◦ on average, but exhibit vigorous oscillations combining the first and second free deformation modes of a cantilevered beam. These large amplitude oscillations excite the flow separation at the model’s trailing edges, leading to significant fluctuations in the separated shear layers and a consequent 31% increase in the global drag. Under yawed conditions, the flaps responses for large values of ���� are different due to the asymmetry of the corresponding recirculation region.This work is a result of the Projects PDC2021-121288-I00, TED2021-131805B-C21 and TED2021-131805B-C22, financed by the Spanish MCIN/ AEI/10.13039/501100011033/, FEDER, UE, and the European Union NextGenerationEU/PRTR. M.L.D. also acknowledges the support from grant FJC2020-043093-I funded by MCIN/AEI/10.13039/501100011033 and European Union NextGenerationEU/PRTR. Finally, J.C.M.H. acknowledges for the support of the Spanish MECD through FPU20/07261. Funding for open access charge: Universidad de Granada / CBUA
Regulation of Protein Secretion Systems Mediated by Cyclic Diguanylate in Plant-Interacting Bacteria
The ubiquitous second messenger cyclic diguanylate (c-di-GMP) is involved in the regulation of different processes in bacteria. In phytopathogens, intracellular fluctuations in the concentration of this molecule contribute to the lifestyle switching from a motile and virulent stage to a sessile and biofilm-forming phase. Among the virulence mechanisms used by bacterial pathogens, different specific type secretion systems (TSSs) and the effector proteins that they translocate are included. Some of these TSS are conceived to suppress host immune responses during bacterial colonization. The modulation of the expression of secretion systems components and/or effector proteins can be influenced by c-di-GMP levels at transcriptional, translational, or post-translational levels and can take place directly by binding to specific or global regulators, or via transducer proteins. Different genera of plant-interacting bacteria have been analyzed to shed some light in the implications of c-di-GMP in the regulation of host plant colonization through protein secretion systems. Expression of (1) adhesins secreted by Type 1 secretion systems to bind the host plant in Pectobacterium (formerly Erwinia) and some beneficial Pseudomonas strains; (2) catalytic exoproteins delivered by Type 2 secretion systems to break plant cell wall in Dickeya; (3) effectors secreted by Type 3 secretion systems to suppress plant immunity in Xanthomonas; or (4) the activity of Type 6 secretion systems to export an ATPase in Pseudomonas, are finely tuned by c-di-GMP levels. In this minireview, we summarize the knowledge available about the implications of c-di-GMP in the regulation of protein secretion in different plant-interacting bacteria.Spanish Ministry of Economy, Industry and Competitivity BIO2016-78409-
Evaluación de la influencia de los recursos computacionales en la QoE del servicio.
The new generation of mobile networks goes beyond radio communications by providing a resilient and flexible architecture. In this context, the virtualization of Radio Access Networks (vRAN) completes the Network Func4on Virtualization (NFV) milestone, enabling a distributed and scalable network architecture. However, this approach increases the complexity of management tasks as computing resources start to play an essential role in the network provisioning process. In this sense, this work aims to assess the impact of computational resources on the delivery of video streaming services. The results obtained prove that inadequate resource assignment to vRAN instances leads to degradation of the Quality of Experience (QoE), even if the allocation of radio resources is adequate for the service.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
GPPP y SDR como una potente herramienta científica
One of the greatest problems in mobile networks that researchers have always faced on, is the difficulty of obtaining data from a real network. The limited access to commercial networks or the high prices which presents the equipment encourages the use of simulators in order to get data or test some algorithms. However, these problems can be solved with the emerging of the concept of SDR and GPPP. Hence, in this work it is presented a framework which enables their use in a scientific field. Moreover, a set of video experiment has been made, whose analysis shows the flexibility that these platforms offer as well as its potential as a wide source of real network data, introducing itself in this way, as a powerful tool for researching
Optimización de señalización en el canal común descendente para el estándar LTE-LAA
The use of unlicensed bands is one of the most promising features envisaged to increase capacity in cellular networks. However, this poses multiple challenges associated to the operation of LTE based standards with coexisting networks, such as WiFi. Previous coexistence analyses have been focused on the user-plane data-related transmissions and mainly based on abstract models. Meanwhile, the effects of the in-band signaling defined by the standards have been mainly disregarded, particularly for ultra-dense scenarios. This paper performs an assessment of how the different in-band signaling mechanisms influence the performance of the coexisting technologies. Based on this analyzed, an optimized signaling solution is envisaged to additionally enhance the service provision in these scenarios.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
The Rhizobial Type 3 Secretion System: The Dr. Jekyll and Mr. Hyde in the Rhizobium–Legume Symbiosis
Rhizobia are soil bacteria that can establish a symbiotic association with legumes. As a result, plant nodules are formed on the roots of the host plants where rhizobia differentiate to bacteroids capable of fixing atmospheric nitrogen into ammonia. This ammonia is transferred to the plant in exchange of a carbon source and an appropriate environment for bacterial survival. This process is subjected to a tight regulation with several checkpoints to allow the progression of the infection or its restriction. The type 3 secretion system (T3SS) is a secretory system that injects proteins, called effectors (T3E), directly into the cytoplasm of the host cell, altering host pathways or suppressing host defense responses. This secretion system is not present in all rhizobia but its role in symbiosis is crucial for some symbiotic associations, showing two possible faces as Dr. Jekyll and Mr. Hyde: it can be completely necessary for the formation of nodules, or it can block nodulation in different legume species/cultivars. In this review, we compile all the information currently available about the effects of different rhizobial effectors on plant symbiotic phenotypes. These phenotypes are diverse and highlight the importance of the T3SS in certain rhizobium–legume symbioses.Ministerio de Ciencia e Innovación PID2019-107634RB-I00Junta de Andalucía P20_00185Universidad de Sevilla FEDER-US 1259948, FEDER-US 125054
Impacto de la asignación de recursos CPU sobre el rendimiento de la vRAN en O-Cloud.
The need for mobile operators to have an infrastructure that can handle everincreasing
traffic and support the development of more demanding services at lower costs
has led to the emergence of the O-RAN paradigm. This organiza.on proposes an unbundled
and virtualized Radio Access Network (vRAN) running on commodity servers, moving away
from tradi.onal monolithic network environments. In this context, managing the available
compu.ng resources at the host machine is key for mee.ng network requirements without
was.ng resources. In this regard, this work abempts to evaluate the impact of
computa.onal and radio resources on network performance under different radio
configura.ons. The results prove that misalloca.ng resources to vRAN instances can lead to
network performance degrada.on and that addi.onal dedicated resources do not always
translate into beber performance.Trabajo financiado por el Ministerio de Asuntos Económicos y Transformación Digital y la Unión Europea a través de fondos NextGenerationEU, en el marco del Plan de Recuperación, Transformación y Resiliencia y el Mecanismo de Recuperación y Resiliencia bajo el proyecto MAORI. Además, ha sido apoyado por el Ministerio de Ciencia e Innovación a través de las becas FPU19/04468 y FPU21/04472. También ha sido parcialmente financiado a través del II Plan Propio de Investigación y Transferencia de la Universidad de Málaga (Campus de Excelencia Internacional Andalucía Tech).
- Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Herramienta de diagnosis para redes móviles basada en puntos sigmas de correlaciones
Mobile network users are demanding with regard to the quality of the services, forcing the operators to solve the network degradations in the shortest time possible. For this purpose, a method for root cause diagnosis of degradations is proposed. It is based on different correlations (among CMs and a KPI) and the weighted average of sigma points to provide a ranking of possible causal candidates. Finally, this method is tested on metrics obtained from a commercial equipment.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Estudio preliminar para el diseño y validación de un cuestionario sobre la percepción de la seguridad según el sistema antivuelco de las porterías en eventos deportivos
The safety of the athletes is basic at sports events and the anti-tip system of the goalposts is an essential element to avoid injuries and accidents in handball/futsal. The objective of this study was to carry out a preliminary study of the design and validation of a new questionnaire to know the opinion of sports agents involved in sports events about the perception of the performance in the handball/futsal game with the goalpost anti-tip system. The content validation was carried out by means of a structured interview with 16 experts and the understanding validity to a sample of 60 participants in the 4 Nations International Handball Tournament held in 2019. Cronbach’s alpha on the items is .860 on a scale 0 -1, which indicates an adequate internal consistency of the items and Friedman’s χ2 test is p < .05, which indicates that individually each included question in the instrument provides relevant information, so this preliminary study indicates that the instrument could be considered valid and reliable to assess the opinion of sports agents on the goalpost anti-tip systemEn los eventos deportivos la seguridad de los deportis-tas es fundamental y el sistema antivuelco de las porte-rías es un elemento imprescindible para evitar lesiones y accidentes en el balonmano/futsal. El objetivo de este estudio fue realizar un estudio preliminar del diseño y validación de un nuevo cuestionario para conocer la opinión de los agentes implicados en los eventos de-portivos acerca de la percepción en el rendimiento del juego del balonmano/futsal del sistema antivuelco de las porterías. La validación de contenido se ha llevado a cabo a través de dieciséis expertos mediante entrevista estructurada y la validez de comprensión determinada por la aplicación del cuestionario a una muestra de 60 participantes en el Torneo Internacional 4 Naciones de Balonmano en el año 2019. El alfa de Cronbach sobre la base de 18 ítems es de .860 en una escala 0-1, lo que indica una consistencia interna adecuada de los ítems, la prueba χ2 de Friedman es de p< .05, lo cual indica que de forma individual cada pregunta incluida en el instrumento aporta información relevante. Este estudio preliminar indica que el instrumento podría considerar-se válido y fiable para valorar la opinión de los agentes deportivos sobre el sistema antivuelco de las porteríasActividad Física y Deport
Regulation and symbiotic significance of nodulation outer proteins secretion in Sinorhizobium fredii HH103
In this work we show that the Sinorhizobium fredii HH103 ttsI gene is essential for the expression
of the tts genes and secretion of nodulation outer proteins (Nops). Moreover, we demonstrate
for the first time, to our knowledge, that the nod box preceding ttsI is necessary for Nops
secretion. TtsI is responsible for the transcriptional activation of nopX, nopA, rhcJ and rhcQ. We
confirm that the S. fredii HH103 ttsI gene is activated by NodD1 and repressed by NolR. In
contrast, NodD2 is not involved in the regulation of ttsI expression. Despite the dependence of
expression of both ttsI and nodA on NodD1 and flavonoids, clear differences in the capacity of
some flavonoids to activate these genes were found. The expression of the ttsI and nodA
genes was also sensitive to differences in the pH of the media. Secretion of Nops in the ttsI
mutant could not be complemented with a DNA fragment containing the ttsI gene and its nod
box, but it was restored when a plasmid harbouring the ttsI, rhcC2 and y4xK genes was
transferred to the mutant strain. The symbiotic effect of Nops secretion was host-dependent but
independent of the type of nodule formed by the host legume. Nops are beneficial in the symbiosis
with Glycine max and Glycyrrhiza uralensis, and detrimental in the case of the tropical legume
Erythrina variegata
- …