Which could be the role of Hybrid Fibre Coax in Next Generation Access networks?

Next generation access networks (NGAN) will support a renewed communication structure where opportunities lie in the provision of ubiquitous broadband connectivity, a wide variety of new applications, appealing contents and a general support to the sustainable growth of diverse sectors. From their deployment it is expected a wealth of innovations, jobs creation and a new wave of economic growth. In this paper we discuss which could be the role of Hybrid Fibre Coax (HFC) in the Next Generation Access Network (NGAN) roadmap. Thus, we propose a simplified model for making approximate cost calculations for HFC deployment based on the geographic and sociodemographic characteristics of Spain. Considering the latest evolution of HFC based on DOCSIS 3.0 from integrated (I-CMTS) towards modular (M-CMTS), the results from the model are compared with the most competitive NGAN for ultrabroadband speeds: Fibre to the Home (FTTH) based on Gigabitcapable Passive Optical Networks (GPON

Comprehensive Study and Optimized Redesign of the CERN's Antiproton Decelerator Target

El Antiproton Decelerator Target (AD-Target) es un dispositivo único responsable de la generación de Antiprotones en la Organización Europea para la Investigación Nuclear (CERN). En operación, intensos haces de protones con una energía de 26 GeV son impactados en su núcleo, un cilindro de 3 mm de diámetro constituido por un material de alta densidad como el iridio, creando partículas secundarias -entre ellas, antiprotones- como consecuencia de las reacciones nucleares inducidas en el interior de éste. La tesis profundiza en las características del target de producción de antiprotones, y en particular, en la respuesta mecánica de su núcleo, el cual está sometido a un incremento de temperatura de aproximademente 2000 grados centígrados en menos de 0.5 microsegundos cada vez que es impactado por el haz de protones primario. Para ello, una metodología combinando técnicas numéricas y experimentales ha sido llevada a cabo. Se han aplicado herramientas computacionales específicas, llamadas hydrocodes, para simular la respuesta dinámica originada en el núcleo del target y su matriz contenedora, hecha de grafito, indicando su potencial fragmentación como resultado de una onda radial de alta frecuencia de presión compresión-tracción generada después de cada impacto del haz de protones. Asimismo, se ha llevado a cabo un experimento llamado HiRadMat27. En éste, varios cilindros de materiales de alta densidad, candidatos para un futuro diseño del target, tales como Ir, W, W-La, Mo, TZM y Ta, han sido expuestos a condiciones dinámicas equivalentes a las alcanzadas en el AD-Target mediante impactos de haces de protones de 440 GeV en la instalación HiRadMat. Se ha usado instrumentación en línea para medir la onda radial pronosticada, confirmando la precisión de las simulaciones de hydrocodes. Todos los materiales irradiados excepto Ta sufrieron agrietamientos internos desde condiciones 5-7 veces menores a las presentes en el AD-Target, mientras que este último aparentemente sobrevivió. La información obtenida ha sido aplicada para proponer un nuevo diseño optimizado del target, el cual incluye un sistema de refrigeración de aire a presión, una nueva configuración en Ta de su núcleo, y una matriz contenedora hecha de grafito expandido (GE). Se han llevado a cabo cálculos de dinámica de fluidos computacional y elementos finitos para validar el sistema de refrigeración y la vida a fatiga del ensamblaje del target. Además, se ha construido un primer prototipo del núcleo del target y su matrix contenedora. Estas actividades marcan la senda para la fabricación de un nuevo lote de targets que garanticen la física de antiprotones en el CERN durante las siguientes décadas de operación.The Antiproton Decelerator Target (AD-Target) is a unique device responsible for the production of antiprotons at the European Organization for Nuclear Research (CERN). During operation, intense 26 GeV energy proton beams are impacted into its core, made of a 3 mm diameter rod of a high density material such as iridium, creating secondary particles -including antiprotons- from the nuclear reactions induced in its interior. This thesis delves into the characteristics of antiproton production and in particular in the mechanical response of the target core material, which is exposed to a rise of temperature of approximate 2000 degrees Celsius in less than 0.5 microseconds each time is impacted by the primary proton beam. A coupled numerical-experimental approach has been applied for this purpose. Specific computational tools, called hydrocodes, have been used for simulating the extreme dynamic response taking place in the target core and its containing graphite matrix, indicating their potential damage and fragmentation as a result of a high frequency radial compressive-to-tensile pressure wave generated after each proton beam impact. A challenging first-of-its-kind experiment called HRMT27 was carried out. Several rods of high density materials, candidate for a future optimized target design, such as Ir, W, W-La, Mo, TZM and Ta were brought to equivalent dynamic conditions as reached in the AD-Target core by impacting them with 440 GeV proton beams using the HiRadMat facility. Online instrumentation was used to measure the predicted radial wave, confirming the accuracy of the hydrocode simulations. All of the irradiated target materials except Ta showed internal cracking from conditions 5-7 times below the present in the AD-Target while the latter apparently survived. Lessons learned are applied for proposing a new optimized target design, including a pressurized-air cooling system, Ta core configuration, and a containing matrix made of expanded graphite (EG). Computational Fluid Dynamic and Structural Finite Element analyses have been carried out to validate the new cooling system and fatigue life of the target assembly. A first prototype of the target core and its containing EG matrix has been built. These activities lead the way into manufacturing a new set of antiproton targets to guarantee antiproton physics at CERN during next decades of operation.L'Antiproton Decelerator Target (AD-Target) és un dispositiu únic responsable de la generació d'Antiprotons a la Organització Europea per la Recerca Nuclear (CERN). En operació, intensos feixos de protons amb una energia de 26 GeV impacten contra el seu nucli, un cilindre de 3 mm de diámetre constituït per un material de densitat alta com l'iridi, creant partícules secundáries - entre elles, antiprotons - com a conseqüència de les reaccions nuclears induïdes a l'interior d'aquest. La tesis profunditza en les característiques del target de producció d'antiprotons i, en particular, a la resposta mecánica del seu nucli, el qual és sotmès a un increment de temperatura de aproximadement 2000 graus centígrads en menys de 0.5 microsegons cada vegada que és impactat pel feix de protons primari. Per aixó, s'ha portat a terme una metodologia que combina tècniques numèriques i experimentals. S'han utilitzat eines computacionals específiques, anomenades hydrocodes, per simular la resposta dinàmica originada al nucli del target i a la seva matriu contenidora, feta de grafit. La dita resposta, indica la seva potencial fragmentació com a resultat d'una ona radial d'alta freqüència de pressió compressió-tracció generada després de cada impact del feix de protons. Així mateix, s'ha portat a terme un experiment anomenat HiRadMat27. En aquest, varis cilindres de materials d'alta densitat, candidats per un futur diseny del target, tals com Ir, W, W-La, Mo, TZM i Ta, han estat exposats a condicions dinàmiques equivalents a les assolides a l'AD-Target mitjanant impactes de feixos de protons de 440 GeV a l'instalació HiRadMat. S'ha utilitzat instrumentació en línia per mesurar l'ona radial pronosticada, confirmant la precisió de les simulacions d'hydrocodes. Tots el materials irradiats excepte Ta van sofrir esquerdaments interns desde condicions de 5-7 vegades menors a les presents a l'AD-Target, mentres que aquest últim aparentment va sobreviure. L'informació obtinguda ha estat aplicada per proposar un nou diseny optimizat del target, el qual inclou un sistema de refrigeració de l'aire a pressió, una nova configuració en Ta del seu nucli, i una matriu contenidora feta de grafit expandit (GE). S'han portat a terme càlculs de dinàmica de fluids computacionals i elements finits per validar el sistema de refrigeració i la vida a fatiga de l'ensambladura del target. S'ha construit un primer prototip del nucli del target i la seva matriu contenidora. Totes aquestes activitats marquen la sendera per a la fabricació del nou lot de targets que garantitzin la física d'antiprotons al CERN durant les següents décades d'operació.Torregrosa Martín, CL. (2018). Comprehensive Study and Optimized Redesign of the CERN's Antiproton Decelerator Target [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/100489TESI

Determination of any pure spatial qudits from a minimum number of measurements by phase-stepping interferometry

We present a proof-of-principle demonstration of a method to characterize any pure spatial qudit of arbitrary dimension d, which is based on the classic phase-shift interferometry technique. In the proposed scheme a total of only 4d measurement outcomes are needed, implying a significant reduction with respect to the standard schemes for quantum-state tomography which require on the order of d^2. By using this technique, we have experimentally reconstructed a large number of states ranging from d=2 up to 14 with mean fidelity values higher than 0.97. For that purpose the qudits were codified in the discretized transverse-momentum position of single photons, once they are sent through an aperture with d slits. We provide an experimental implementation of the method based in a Mach-Zehnder interferometer, which allows one to reduce the number of measurement settings to four since the d slits can be measured simultaneously. Furthermore, it can be adapted to consider the reconstruction of the unknown state from the outcome frequencies of 4d−3 fixed projectors independently of the encoding or the nature of the quantum system, allowing one to implement the reconstruction method in a general experiment.Fil: Pears Stefano, Quimey Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; ArgentinaFil: Rebón, Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Ledesma, Silvia Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; ArgentinaFil: Iemmi, Claudio César. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentin

Extração, caracterização parcial e susceptibilidade ao Hg2+ da fosfatase ácida da microalga Pseudokirchneriella subcapitata

Pseudokirchneriella subcapitata is a unicellular green algae widely distributed in freshwater and soils. Due to its cosmopolitan characteristic, its use is recommended by national and international protocols in ecotoxicity studies. The alteration of phosphatase activities by agriculture pollutants like heavy metals has been extensively used as a biomarker in risk assessment and biomonitoring. In this study, we compared the extraction of acid phosphatase from P. subcapitata by different procedures and we studied the stability, substrates specificity, kinetics and the effect of Hg2+ in the crude extract. The freezing and thawing technique associated with probe sonication was the most suitable method of extraction. The enzyme was stable when frozen at -20ºC for at least six months, showed an optimum pH of 5 and a Km value of 0.27 mM for p-nitrophenylphosphate (pNPP) as substrate. Some natural organic substrates were cleaved by a similar extent as the synthetic substrate pNPP. Short term exposure (24 hours) to Hg2+ had little effect but inhibition of the specific activity was observed after 7 days with EC50 (concentration of Hg2+ that promotes 50% decrease of specific activity) value of 12.63 μM Hg2+.Pseudokirchneriella subcapitata é uma alga verde unicelular amplamente distribuída em corpos d´agua e solos. Devido a sua natureza cosmopolita, seu uso é recomendado por protocolos nacionais e internacionais na realização de estudos de ecotoxicidade. A alteração da atividade de fosfatases por agentes poluentes de origem agrícola, como metais pesados, tem sido largamente usada como um biomarcador na avaliação de risco e biomonitoramento. No presente trabalho foi comparada a extração da fosfatase ácida de P. subcapitata por diferentes métodos e estudada a sua estabilidade, especificidade por substratos, cinética e efeito do Hg2+ no extrato bruto. O congelamento e descongelamento, associado com ultrassom, foi o método que proporcionou maior rendimento de extração. A enzima, praticamente estável por armazenamento a -20ºC, durante aproximadamente seis meses, demonstrou uma atividade ótima em pH 5 e um valor de Km para o p-nitrofenilfostato (pNPP) de 0,27 mM. Alguns substratos naturais foram hidrolisados com uma intensidade semelhante à do substrato sintético pNPP. Diferentemente dos estudos de exposição a curto prazo (24 horas), observou-se inibição da atividade específica nas culturas expostas durante 7 dias, com um valor de CE50 (concentração de Hg2+ que promove 50% de decréscimo da atividade específica) equivalente a 12,63 μM Hg2+

Generalized q -plates and alternative kinds of vector and vortex beams

We took a generalization of the conventional concept of the q-plate, allowing in its definition nonlinear functions of the azimuthal coordinate, and simulated the resulting fields of applying this kind of element to uniformly polarized input beams, both in the near-field (Fresnel diffraction) and the far-field (Fraunhofer diffraction) approximations. In general terms, when working in the near-field regime, the chosen function defines the output polarization structure for linearly polarized input beams and the phase of the output field for circularly polarized input beams. In the far-field regime, it is obtained that when there are nonlinearities in the azimuthal variable, the central singularity of the polarization field of a vector or vortex beam may divide into several singularities of lower topological charge, preserving the total charge. Depending on the chosen q-plate function, different particular behaviors on the output beam are observed, which offers a whole range of possibilities for creating alternative kinds of vector and vortex beams, as well as polarization critical points and singularity distributions.Fil: Vergara, Martín Alexis. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Procesado de Imágenes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Iemmi, Claudio César. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Procesado de Imágenes; Argentin

A simple laboratory class using a Pseudomonas aeruginosa auxotroph to illustrate UV-mutagenic killing, DNA photorepair and mutagenic DNA repair

A simple and cheap laboratory class is proposed to illustrate the lethal effect of UV radiation on bacteria and the operation of different DNA repair mechanisms. The class is divided into two sessions, an initial 3-hour experimental session and a second 2-hour analytical session. The experimental session involves two separate experiments: one dedicated to illustrating the lethal effect of UV radiation and the protective effect of DNA photorepair; the second to explore the operation of DNA repair mechanisms that prioritise survival but introduce mutations. The procedure makes use of a Pseudomonas aeruginosa double auxotroph, which serves to detect UV-induced back-mutations to prototrophy. The proposed scheme is carried out by undergraduate students of the Bacterial Physiology and Genetics course, as part of our Biotechnology curriculum. We think that it will be a valuable tool for microbiology students to increase their understanding of basic genetic concepts.Fil: Sobrero, Patricio Martín. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Valverde, Claudio Fabián. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

The bacterial protein Hfq: Much more than a mere RNA-binding factor

Most of the sequenced bacterial genomes contain a gene encoding a protein known as Hfq that resembles the eukaryotic RNA-binding proteins of the LSm family. It was originally identified in Escherichia coli as a host factor required for replication of the Qβ RNA phage. In this review, we present a comprehensive summary of 40 years of investigation to learn that Hfq is an influential, though not essential, global regulator of gene expression in bacteria and that this feature is undoubtedly linked to Hfq's RNA-binding properties. This protein intervenes in different RNA transactions, notably the promotion of antisense interactions between messenger RNAs and small regulatory RNAs. Yet, several aspects of its molecular mechanism remain not understood. In addition, mechanistic studies have been exclusively carried out in enterobacterial models, highlighting the need to expand the research on Hfq function to other taxons. Upon reviewing the genetic, structural, biochemical, and biological aspects of this extraordinary protein, we discuss recent findings on interactions with macromolecules other than RNA suggesting a broader participation of Hfq in major steps in the flow of genetic information. We show that, although significant progress has been achieved to elucidate Hfq role at the molecular level, many open questions remain.Fil: Sobrero, Patricio Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Valverde, Claudio Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentin

Evidences of autoregulation of hfq expression in Sinorhizobium meliloti strain 2011

Riboregulation comprises gene expression regulatory mechanisms that rely upon the activity of small non-coding RNAs (sRNAs) and in most cases RNA binding proteins. In c-proteobacteria, the Sm-like protein Hfq is a key player in riboregulatory processes, because it promotes sRNA-mRNA interactions and influences mRNA polyadenylation or translation. In the α-proteobacterium Sinorhizobium meliloti, the large number of detected small RNA transcripts and the pleiotropic effects of hfq mutations lead to the hypothesis that riboregulatory mechanisms are important in this soil microorganism to adjust gene expression both in free-living conditions and as a nitrogenfixing endosymbiont within legume root nodules. In this study, homology modeling of S. meliloti Hfq protein and cross-complementation experiments of S. meliloti and Escherichia coli mutants indicates that hfq Sm encodes an RNA chaperone that can be functionally exchanged by its homolog from E. coli. A transcriptional and translational analysis of S. meliloti hfq expression by means of lacZ reporter fusions strongly suggests that the S. meliloti Hfq protein autocontrols its expression at the translational level, a phenomenon that was evident in the natural host S. meliloti as well as in the heterologous host E. coli.Fil: Sobrero, Patricio Martín. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Valverde, Claudio Fabián. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Comparative Genomics and Evolutionary Analysis of RNA-Binding Proteins of the CsrA Family in the Genus Pseudomonas

Gene expression is adjusted according to cellular needs through a combination of mechanisms acting at different layers of the flow of genetic information. At the posttranscriptional level, RNA-binding proteins are key factors controlling the fate of nascent and mature mRNAs. Among them, the members of the CsrA family are small dimeric proteins with heterogeneous distribution across the bacterial tree of life, that act as global regulators of gene expression because they recognize characteristic sequence/structural motifs (short hairpins with GGA triplets in the loop) present in hundreds of mRNAs. The regulatory output of CsrA binding to mRNAs is counteracted in most cases by molecular mimic, non-protein coding RNAs that titrate the CsrA dimers away from the target mRNAs. In γ-proteobacteria, the regulatory modules composed by CsrA homologs and the corresponding antagonistic sRNAs, are mastered by two-component systems of the GacS-GacA type, which control the transcription and the abundance of the sRNAs, thus constituting the rather linear cascade Gac-Rsm that responds to environmental or cellular signals to adjust and coordinate the expression of a set of target genes posttranscriptionally. Within the γ-proteobacteria, the genus Pseudomonas has been shown to contain species with different number of active CsrA (RsmA) homologs and of molecular mimic sRNAs. Here, with the help of the increasing availability of genomic data we provide a comprehensive state-of-the-art picture of the remarkable multiplicity of CsrA lineages, including novel yet uncharacterized paralogues, and discuss evolutionary aspects of the CsrA subfamilies of the genus Pseudomonas, and implications of the striking presence of csrA alleles in natural mobile genetic elements (phages and plasmids).Fil: Sobrero, Patricio Martín. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Centro de Bioquímica y Microbiología de Suelos. Laboratorio de Fisiología, Genética de Bacterias para Plantas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Valverde, Claudio Fabián. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Centro de Bioquímica y Microbiología de Suelos. Laboratorio de Fisiología, Genética de Bacterias para Plantas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin