Orchestrating datacenters and networks to facilitate the telecom cloud

In the Internet of services, information technology (IT) infrastructure providers play a critical role in making the services accessible to end-users. IT infrastructure providers host platforms and services in their datacenters (DCs). The cloud initiative has been accompanied by the introduction of new computing paradigms, such as Infrastructure as a Service (IaaS) and Software as a Service (SaaS), which have dramatically reduced the time and costs required to develop and deploy a service. However, transport networks become crucial to make services accessible to the user and to operate DCs. Transport networks are currently configured with big static fat pipes based on capacity over-provisioning aiming at guaranteeing traffic demand and other parameters committed in Service Level Agreement (SLA) contracts. Notwithstanding, such over-dimensioning adds high operational costs for DC operators and service providers. Therefore, new mechanisms to provide reconfiguration and adaptability of the transport network to reduce the amount of over-provisioned bandwidth are required. Although cloud-ready transport network architecture was introduced to handle the dynamic cloud and network interaction and Elastic Optical Networks (EONs) can facilitate elastic network operations, orchestration between the cloud and the interconnection network is eventually required to coordinate resources in both strata in a coherent manner. In addition, the explosion of Internet Protocol (IP)-based services requiring not only dynamic cloud and network interaction, but also additional service-specific SLA parameters and the expected benefits of Network Functions Virtualization (NFV), open the opportunity to telecom operators to exploit that cloud-ready transport network and their current infrastructure, to efficiently satisfy network requirements from the services. In the telecom cloud, a pay-per-use model can be offered to support services requiring resources from the transport network and its infrastructure. In this thesis, we study connectivity requirements from representative cloud-based services and explore connectivity models, architectures and orchestration schemes to satisfy them aiming at facilitating the telecom cloud. The main objective of this thesis is demonstrating, by means of analytical models and simulation, the viability of orchestrating DCs and networks to facilitate the telecom cloud. To achieve the main goal we first study the connectivity requirements for DC interconnection and services on a number of scenarios that require connectivity from the transport network. Specifically, we focus on studying DC federations, live-TV distribution, and 5G mobile networks. Next, we study different connectivity schemes, algorithms, and architectures aiming at satisfying those connectivity requirements. In particular, we study polling-based models for dynamic inter-DC connectivity and propose a novel notification-based connectivity scheme where inter-DC connectivity can be delegated to the network operator. Additionally, we explore virtual network topology provisioning models to support services that require service-specific SLA parameters on the telecom cloud. Finally, we focus on studying DC and network orchestration to fulfill simultaneously SLA contracts for a set of customers requiring connectivity from the transport network.En la Internet de los servicios, los proveedores de recursos relacionados con tecnologías de la información juegan un papel crítico haciéndolos accesibles a los usuarios como servicios. Dichos proveedores, hospedan plataformas y servicios en centros de datos. La oferta plataformas y servicios en la nube ha introducido nuevos paradigmas de computación tales como ofrecer la infraestructura como servicio, conocido como IaaS de sus siglas en inglés, y el software como servicio, SaaS. La disponibilidad de recursos en la nube, ha contribuido a la reducción de tiempos y costes para desarrollar y desplegar un servicio. Sin embargo, para permitir el acceso de los usuarios a los servicios así como para operar los centros de datos, las redes de transporte resultan imprescindibles. Actualmente, las redes de transporte están configuradas con conexiones estáticas y su capacidad sobredimensionada para garantizar la demanda de tráfico así como los distintos parámetros relacionados con el nivel de servicio acordado. No obstante, debido a que el exceso de capacidad en las conexiones se traduce en un elevado coste tanto para los operadores de los centros de datos como para los proveedores de servicios, son necesarios nuevos mecanismos que permitan adaptar y reconfigurar la red de forma eficiente de acuerdo a las nuevas necesidades de los servicios a los que dan soporte. A pesar de la introducción de arquitecturas que permiten la gestión de redes de transporte y su interacción con los servicios en la nube de forma dinámica, y de la irrupción de las redes ópticas elásticas, la orquestación entre la nube y la red es necesaria para coordinar de forma coherente los recursos en los distintos estratos. Además, la explosión de servicios basados el Protocolo de Internet, IP, que requieren tanto interacción dinámica con la red como parámetros particulares en los niveles de servicio además de los habituales, así como los beneficios que se esperan de la virtualización de funciones de red, representan una oportunidad para los operadores de red para explotar sus recursos y su infraestructura. La nube de operador permite ofrecer recursos del operador de red a los servicios, de forma similar a un sistema basado en pago por uso. En esta Tesis, se estudian requisitos de conectividad de servicios basados en la nube y se exploran modelos de conectividad, arquitecturas y modelos de orquestación que contribuyan a la realización de la nube de operador. El objetivo principal de esta Tesis es demostrar la viabilidad de la orquestación de centros de datos y redes para facilitar la nube de operador, mediante modelos analíticos y simulaciones. Con el fin de cumplir dicho objetivo, primero estudiamos los requisitos de conectividad para la interconexión de centros de datos y servicios en distintos escenarios que requieren conectividad en la red de transporte. En particular, nos centramos en el estudio de escenarios basados en federaciones de centros de datos, distribución de televisión en directo y la evolución de las redes móviles hacia 5G. A continuación, estudiamos distintos modelos de conectividad, algoritmos y arquitecturas para satisfacer los requisitos de conectividad. Estudiamos modelos de conectividad basados en sondeos para la interconexión de centros de datos y proponemos un modelo basado en notificaciones donde la gestión de la conectividad entre centros de datos se delega al operador de red. Estudiamos la provisión de redes virtuales para soportar en la nube de operador servicios que requieren parámetros específicos en los acuerdos de nivel de servicio además de los habituales. Finalmente, nos centramos en el estudio de la orquestación de centros de datos y redes con el objetivo de satisfacer de forma simultánea requisitos para distintos servicios.Postprint (published version

An escape room for an alternative evaluation system

Our traditional education system spins around evaluation and its traditional grading system: summative assessment. In that system, professors spend time and effort trying to be “fair” when they mark the exercises, while students' main concern is snatching enough points to pass. We believe learning should be at the center. Students should put their energy on learning and professors on facilitating this learning process. However, we are still required to give a mark. We propose a game to achieve formative assessment. Play is a source of motivation to both engage students and enhance learning. The aim is that students should learn and enjoy their learning. We have designed an escape room with different sets of questions, each set corresponds to one topic. The student is presented with one activity to solve correctly. There is no grading but feedback: the answer can either be correct or incorrect. If the answer is correct, the student moves on to the next set of questions, otherwise the student is challenged with another activity of the same set. This goes on until the student solves one exercise correctly of each set. The student can only escape the room if one exercise of each topic is solved correctly. All activities proposed are of a basic level and if the student escapes the room he has a pass. Another bundle of sets can be done with more advanced exercises and if the student escapes the room he would achieve a higher mark. The method emphasizes two fundamental (but neglected) aspects of education: (i) the joy of learning; and (ii) diversity, as we give students as many opportunities as they need to learn at their own pace without penalty.This work has been supported by the Institut de Ciències de l’Educació (ICE) Convocatòria de projectes d’innovació docent 2021 (Acord CG/2021/02/34, de 9 d'abril de 2021) and by Escola Tècnica d’Enginyeria de Telecomunicació (upctelecos-BarcelonaTech).Peer ReviewedPostprint (published version

Meeting the requirements to deploy cloud RAN over optical networks

Radio access network (RAN) cost savings are expected in future cloud RAN (C-RAN). In contrast to traditional distributed RAN architectures, in C-RAN, remote radio heads (RRHs) from different sites can share baseband processing resources from virtualized baseband unit pools placed in a few central locations (COs). Due to the stringent requirements of the several interfaces needed in C-RAN, optical networks have been proposed to support C-RAN. One of the key elements that needs to be considered are optical transponders. Specifically, sliceable bandwidth-variable transponders (SBVTs) have recently shown many advantages for core optical transport networks. In this paper, we study the connectivity requirements of C-RAN applications and conclude that dynamicity, fine granularity, and elasticity are needed. However, there is no SBVT implementation that supports those requirements, and thus, we propose and assess an SBVT architecture based on dynamic optical arbitrary generation/measurement. We consider different long-term evolution-advanced configurations and study the impact of the centralization level in terms of the capital expense and operating expense. An optimization problem is modeled to decide which COs should be equipped and which equipment, including transponders, needs to be installed. The results show noticeable cost savings from installing the proposed SBVTs compared to installing fixed transponders. Finally, compared to the maximum centralization level, remarkable cost savings are shown when a lower level of centralization is considered.Peer ReviewedPostprint (author's final draft

Assessment of Multilocus Sequence Analysis (MLSA) for Identification of Candidatus Liberibacter Solanacearum from Different Host Plants in Spain

[EN] Liberibacteris a bacterial group causing different diseases and disorders in plants. Among liberibacters,CandidatusLiberibacter solanaceraum (CLso) produces disorders in several species mainly within Apiaceae and Solanaceae families. CLso isolates are usually grouped in defined haplotypes according to single nucleotide polymorphisms in genes associated with ribosomal elements. In order to characterize more precisely isolates of CLso identified in potato in Spain, a Multilocus Sequence Analysis (MLSA) was applied. This methodology was validated by a complete analysis of ten housekeeping genes that showed an absence of positive selection and a nearly neutral mechanism for their evolution. Most of the analysis performed with single housekeeping genes, as well as MLSA, grouped together isolates of CLso detected in potato crops in Spain within the haplotype E, undistinguishable from those infecting carrots, parsnips or celery. Moreover, the information from these housekeeping genes was used to estimate the evolutionary divergence among the different CLso by using the concatenated sequences of the genes assayed. Data obtained on the divergence among CLso haplotypes support the hypothesis of evolutionary events connected with different hosts, in different geographic areas, and possibly associated with different vectors. Our results demonstrate the absence in Spain of CLso isolates molecularly classified as haplotypes A and B, traditionally considered causal agents of zebra chip in potato, as well as the uncertain possibility of the present haplotype to produce major disease outbreaks in potato that may depend on many factors that should be further evaluated in future worksThis research was funded by Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA), grant numbers AT2016-007 and RTA2014-00008-C04-03-E, co-financed by FEDER.Ruiz-Padilla, A.; Redondo, C.; Asensio, A.; Garita-Cambronero, J.; Martinez, C.; Perez-Padilla, V.; Marquinez, R.... (2020). Assessment of Multilocus Sequence Analysis (MLSA) for Identification of Candidatus Liberibacter Solanacearum from Different Host Plants in Spain. Microorganisms. 8(9):1-19. https://doi.org/10.3390/microorganisms8091446S11989Haapalainen, M. (2014). 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Microbial Biotechnology, 10(4), 833-844. doi:10.1111/1751-7915.12707Alfaro-Fernández, A., Hernández-Llopis, D., & Font, M. I. (2017). Haplotypes of ‘Candidatus Liberibacter solanacearum’ identified in Umbeliferous crops in Spain. European Journal of Plant Pathology, 149(1), 127-131. doi:10.1007/s10658-017-1172-2Haapalainen, M., Wang, J., Latvala, S., Lehtonen, M. T., Pirhonen, M., & Nissinen, A. I. (2018). Genetic Variation of ‘Candidatus Liberibacter solanacearum’ Haplotype C and Identification of a Novel Haplotype from Trioza urticae and Stinging Nettle. Phytopathology®, 108(8), 925-934. doi:10.1094/phyto-12-17-0410-rHaapalainen, M., Latvala, S., Wickström, A., Wang, J., Pirhonen, M., & Nissinen, A. I. (2019). A novel haplotype of ‘Candidatus Liberibacter solanacearum’ found in Apiaceae and Polygonaceae family plants. European Journal of Plant Pathology, 156(2), 413-423. doi:10.1007/s10658-019-01890-0Mauck, K. E., Sun, P., Meduri, V. R., & Hansen, A. K. (2019). New Ca. Liberibacter psyllaurous haplotype resurrected from a 49-year-old specimen of Solanum umbelliferum: a native host of the psyllid vector. Scientific Reports, 9(1). doi:10.1038/s41598-019-45975-6Teixeira, D. C., Eveillard, S., Sirand-Pugnet, P., Wulff, A., Saillard, C., Ayres, A. J., & Bove, J. M. (2008). The tufB-secE-nusG-rplKAJL-rpoB gene cluster of the liberibacters: sequence comparisons, phylogeny and speciation. INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 58(6), 1414-1421. doi:10.1099/ijs.0.65641-0Glaeser, S. P., & Kämpfer, P. (2015). Multilocus sequence analysis (MLSA) in prokaryotic taxonomy. Systematic and Applied Microbiology, 38(4), 237-245. doi:10.1016/j.syapm.2015.03.007Gevers, D., Cohan, F. M., Lawrence, J. G., Spratt, B. G., Coenye, T., Feil, E. J., … Swings, J. (2005). Re-evaluating prokaryotic species. Nature Reviews Microbiology, 3(9), 733-739. doi:10.1038/nrmicro1236Swisher Grimm, K. D., & Garczynski, S. F. (2019). Identification of a New Haplotype of ‘CandidatusLiberibacter solanacearum’ inSolanum tuberosum. Plant Disease, 103(3), 468-474. doi:10.1094/pdis-06-18-0937-reLin, H., Lou, B., Glynn, J. M., Doddapaneni, H., Civerolo, E. L., Chen, C., … Vahling, C. M. (2011). The Complete Genome Sequence of ‘Candidatus Liberibacter solanacearum’, the Bacterium Associated with Potato Zebra Chip Disease. PLoS ONE, 6(4), e19135. doi:10.1371/journal.pone.0019135Thompson, S. M., Johnson, C. P., Lu, A. Y., Frampton, R. A., Sullivan, K. L., Fiers, M. W. E. J., … Smith, G. R. (2015). Genomes of ‘Candidatus Liberibacter solanacearum’ Haplotype A from New Zealand and the United States Suggest Significant Genome Plasticity in the Species. Phytopathology®, 105(7), 863-871. doi:10.1094/phyto-12-14-0363-fiLin, H., Pietersen, G., Han, C., Read, D. A., Lou, B., Gupta, G., & Civerolo, E. L. (2015). Complete Genome Sequence of « Candidatus Liberibacter africanus,» a Bacterium Associated with Citrus Huanglongbing. Genome Announcements, 3(4). doi:10.1128/genomea.00733-15Wulff, N. A., Zhang, S., Setubal, J. C., Almeida, N. F., Martins, E. C., Harakava, R., … Gabriel, D. W. (2014). The Complete Genome Sequence of ‘Candidatus Liberibacter americanus’, Associated with Citrus Huanglongbing. Molecular Plant-Microbe Interactions®, 27(2), 163-176. doi:10.1094/mpmi-09-13-0292-rDuan, Y., Zhou, L., Hall, D. G., Li, W., Doddapaneni, H., Lin, H., … Gottwald, T. (2009). Complete Genome Sequence of Citrus Huanglongbing Bacterium, ‘CandidatusLiberibacter asiaticus’ Obtained Through Metagenomics. Molecular Plant-Microbe Interactions®, 22(8), 1011-1020. doi:10.1094/mpmi-22-8-1011Katoh, H., Miyata, S., Inoue, H., & Iwanami, T. (2014). Unique Features of a Japanese ‘Candidatus Liberibacter asiaticus’ Strain Revealed by Whole Genome Sequencing. PLoS ONE, 9(9), e106109. doi:10.1371/journal.pone.0106109Leonard, M. T., Fagen, J. R., Davis-Richardson, A. G., Davis, M. J., & Triplett, E. W. (2012). Complete genome sequence of Liberibacter crescens BT-1. Standards in Genomic Sciences, 7(2), 271-283. doi:10.4056/sigs.3326772Teresani, G. R., Bertolini, E., Alfaro-Fernández, A., Martínez, C., Tanaka, F. A. O., Kitajima, E. W., … Font, M. I. (2014). Association of ‘Candidatus Liberibacter solanacearum’ with a Vegetative Disorder of Celery in Spain and Development of a Real-Time PCR Method for Its Detection. Phytopathology®, 104(8), 804-811. doi:10.1094/phyto-07-13-0182-rLi, W., Hartung, J. S., & Levy, L. (2006). Quantitative real-time PCR for detection and identification of Candidatus Liberibacter species associated with citrus huanglongbing. Journal of Microbiological Methods, 66(1), 104-115. doi:10.1016/j.mimet.2005.10.018Munyaneza, J. E., Sengoda, V. G., Crosslin, J. M., De la Rosa-Lozano, G., & Sanchez, A. (2009). First Report of ‘Candidatus Liberibacter psyllaurous’ in Potato Tubers with Zebra Chip Disease in Mexico. Plant Disease, 93(5), 552-552. doi:10.1094/pdis-93-5-0552aPhillips, J. L., & Gnanakaran, S. (2014). A data-driven approach to modeling the tripartite structure of multidrug resistance efflux pumps. Proteins: Structure, Function, and Bioinformatics, 83(1), 46-65. doi:10.1002/prot.24632Kumar, S., Stecher, G., Li, M., Knyaz, C., & Tamura, K. (2018). MEGA X: Molecular Evolutionary Genetics Analysis across Computing Platforms. Molecular Biology and Evolution, 35(6), 1547-1549. doi:10.1093/molbev/msy096Estimation of the number of nucleotide substitutions in the control region of mitochondrial DNA in humans and chimpanzees. (1993). Molecular Biology and Evolution. doi:10.1093/oxfordjournals.molbev.a040023Rozas, J., Ferrer-Mata, A., Sánchez-DelBarrio, J. C., Guirao-Rico, S., Librado, P., Ramos-Onsins, S. E., & Sánchez-Gracia, A. (2017). DnaSP 6: DNA Sequence Polymorphism Analysis of Large Data Sets. Molecular Biology and Evolution, 34(12), 3299-3302. doi:10.1093/molbev/msx248Liao, J., Wiedmann, M., & Kovac, J. (2017). Genetic Stability and Evolution of the sigB Allele, Used for Listeria Sensu Stricto Subtyping and Phylogenetic Inference. Applied and Environmental Microbiology, 83(12). doi:10.1128/aem.00306-17Tamura, K., Battistuzzi, F. U., Billing-Ross, P., Murillo, O., Filipski, A., & Kumar, S. (2012). Estimating divergence times in large molecular phylogenies. Proceedings of the National Academy of Sciences, 109(47), 19333-19338. doi:10.1073/pnas.1213199109Tamura, K., Tao, Q., & Kumar, S. (2018). Theoretical Foundation of the RelTime Method for Estimating Divergence Times from Variable Evolutionary Rates. Molecular Biology and Evolution, 35(7), 1770-1782. doi:10.1093/molbev/msy044López-Hermoso, C., de la Haba, R. R., Sánchez-Porro, C., Papke, R. T., & Ventosa, A. (2017). Assessment of MultiLocus Sequence Analysis As a Valuable Tool for the Classification of the Genus Salinivibrio. Frontiers in Microbiology, 8. doi:10.3389/fmicb.2017.01107Hajri, A., Loiseau, M., Cousseau-Suhard, P., Renaudin, I., & Gentit, P. (2017). Genetic Characterization of ‘Candidatus Liberibacter solanacearum’ Haplotypes Associated with Apiaceous Crops in France. Plant Disease, 101(8), 1383-1390. doi:10.1094/pdis-11-16-1686-reFang, Y., Wang, Y., Liu, Z., Dai, H., Cai, H., Li, Z., … Wang, D. (2019). Multilocus Sequence Analysis, a Rapid and Accurate Tool for Taxonomic Classification, Evolutionary Relationship Determination, and Population Biology Studies of the Genus Shewanella. Applied and Environmental Microbiology, 85(11). doi:10.1128/aem.03126-18Konstantinidis, K. T., Ramette, A., & Tiedje, J. M. (2006). Toward a More Robust Assessment of IntraspeciesDiversity, Using Fewer GeneticMarkers. Applied and Environmental Microbiology, 72(11), 7286-7293. doi:10.1128/aem.01398-06Ajene, I. J., Khamis, F., Ballo, S., Pietersen, G., van Asch, B., Seid, N., … Mohamed, S. (2020). Detection of Asian Citrus Psyllid (Hemiptera: Psyllidae) in Ethiopia: A New Haplotype and its Implication to the Proliferation of Huanglongbing. Journal of Economic Entomology, 113(4), 1640-1647. doi:10.1093/jee/toaa113Thapa, S. P., De Francesco, A., Trinh, J., Gurung, F. B., Pang, Z., Vidalakis, G., … Coaker, G. (2020). Genome‐wide analyses of Liberibacter species provides insights into evolution, phylogenetic relationships, and virulence factors. Molecular Plant Pathology, 21(5), 716-731. doi:10.1111/mpp.12925Antolinez, C. A., Fereres, A., & Moreno, A. (2017). Risk assessment of ‘Candidatus Liberibacter solanacearum’ transmission by the psyllids Bactericera trigonica and B. tremblayi from Apiaceae crops to potato. 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COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

ESTRUCTURA DE COMPUTADORS I (Examen 2n quadrimestre)

Examen final del curs 2017-2018