131 research outputs found

    Implementaciones hardware de circuitos aritméticos sobre cuerpos finitos (Hardwareimolementations of arithmetic circuits over finite field)

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    La aritmética sobre cuerpos finitos ha recibido mucho interés debido a su importancia en criptografía, control de errores de codificación y procesado de señales digitales. Una gran parte del tiempo de las rutinas criptográficas se dedica al cálculo de operaciones aritméticas sobre cuerpos finitos. Los sistemas que usan esta aritmética deben ser rápidos debido a los rendimientos requeridos en los sistemas de comunicación actuales. La suma en GF(2^m) es una operación XOR binaria independiente, puede ser realizada de forma rápida y sin retardo. Sin embargo otras operaciones son mucho más complejas y con mayor retardo. La eficiencia de las implementaciones hardware se mide en términos del número de puertas (XOR y AND) y del retardo total debido a esas puertas del circuito. El objetivo de este documento es hacer un estudio comparativo de diferentes circuitos aritméticos sobre GF(2^m), se utilizarán los cuerpos recomendados por el NIST y el SECG. Por su importancia, se han estudiado diferentes implementaciones para los algoritmos de multiplicación, tanto multiplicación serie como paralela junto con multiplicación dígito serie. Para el estudio de toras operaciones aritméticas, también se estudian algoritmos para obtener el cuadrado y el inverso de elementos pertencientes a GF(2^m). Para realizar este trabajo se implentarán los algoritmos mencionados en VHDL para FPGAs estudiando el consumo de área y tiempo de las operaciones comparando los resultados entre sí y con los obtenidos por otros autores. [ABSTRACT]Finite field arithmetic has received much attention due to its importance in cryptography, error control coding and digital signal processing. A large portion of time from the routines of the cryptographies algorithms is used in the calculation of arithmetic operations on finite fields. Systems using this arithmetic must be faster because of performance required in current communication systems. Addition in GF(2^m) is bit independent XOR operation, it can be implemented in fast and inexpensive ways. Nevertheless other operations are much more complex and expensive. The efficiency of the hardware implementations is measured in terms of the numbers of gates (XOR and AND) and of the total gate delay of the circuit. The aim of this document is to make a comparative study of different arithmetic circuits over GF(2^m), NIST and SECG recommended fields will be used. Due to multiplication is one of the most complex and important operation in finite field arithmetic, different implementations will be treated, parallel and serial along with digit-serial algorithms. To perform other operations, also inversion and square algorithms over GF(2^m) have been discussed. VHDL implementations of these algorithms for FPGAs have been realized to study time and area consumption and to compare the result each other and with other authors'results

    ¡Quién me mandaría a mí...! Tribulaciones de una comunicante algo masoca (monólogo)

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    [ES] En este artículo se explica, en forma de monólogo, todo el proceso por el que se ha de pasar cuando a los biblioteca- rios se nos solicita presentar una comunicación en un congreso. Con gran sentido del humor se describen todos los pormenores que se deben sufrir cuando se hace frente a una experiencia de este tipo

    Leer con y para otros. 12TL#lectura3D, Lectura y conversación desde Peñaranda de Bracamonte

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    [ES] La red de lectura y conversación desde Peñaranda, creada en 2012, entreteje lectores y traza rutas de lectura. Sus propuestas se dividen en dos grandes bloques: la lectura compartida y la lectura solidaria. En este artículo se detalla en qué consiste cada una de esas propuestas y se realiza una valoración sobre ellas

    Propuesta de los principios pedagógicos del Padre Morales dirigida a educadores universitarios para lograr una formación integral de los postmillenials

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    La investigación busca brindar un plan de formación a docentes universitarios que los ayude en la educación integral de sus alumnos, enfatizando en el desarrollo de las tres facultades de la persona: entendimiento, que busca la verdad, voluntad para hacer el bien y el amor para vivir en verdad y bien. Con ello, sus alumnos pueden adquirir valores y el sentido pleno a su vida. Todo ello tomando como referencia la pedagogía propuesta por el P. Tomás Morales S. J., quien propone cuatro principios educativos: mística de exigencia, espíritu combativo, cultivo de la reflexión y escuela de constancia. Después de analizar las características de los jóvenes universitarios, que son parte de la generación post millennials, inmersos en una sociedad “líquida” con grandes influencias ideológicas, pero que, a su vez, descubren en sí el anhelo de perfección propio de toda persona humana; y las características de los docentes universitarios, que deben ser guías y testigos en su labor educativa, se presentan los principios y rasgos de la pedagogía del P. Tomás Morales a la luz de sus escritos, como modelos de educación. Finalmente, se estructura el plan de formación basado en seis medios: encuentro trascendental personal, talleres de formación integral, encuentro de universitarios, jornadas pedagógicas, coloquios docentes-estudiantes y acompañamiento docente

    Isolated pseudo-RNA-recognition motifs of SR proteins can regulate splicing using a noncanonical mode of RNA recognition

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    Serine/arginine (SR) proteins, one of the major families of alternativesplicing regulators in Eukarya, have two types of RNA-recognition motifs (RRMs): a canonical RRM and a pseudo-RRM. Although pseudo-RRMs are crucial for activity of SR proteins, their mode of action was unknown. By solving the structure of the human SRSF1 pseudo-RRM bound to RNA, we discovered a very unusual and sequence-specific RNA-binding mode that is centered on one a-helix and does not involve the β-sheet surface, which typically mediates RNA binding by RRMs. Remarkably, this mode of binding is conserved in all pseudo-RRMs tested. Furthermore, the isolated pseudo- RRM is sufficient to regulate splicing of about half of the SRSF1 target genes tested, and the bound a-helix is a pivotal element for this function. Our results strongly suggest that SR proteins with a pseudo-RRM frequently regulate splicing by competing with, rather than recruiting, spliceosome components, using solely this unusual RRM

    Singlet oxygen triggers chloroplast rupture and cell death in the zeaxanthin epoxidase defective mutant aba1 of Arabidopsis thaliana under high light stress

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    [EN] The two Arabidopsis thaliana mutants, aba1 and max4, were previously identified as sharing a number of coregulated genes with both the flu mutant and Arabidopsis cell suspension cultures exposed to high light (HL). On this basis, we investigated whether aba1 and max4 were generating high amounts of singlet oxygen (1O2) and activating 1O2-mediated cell death. Thylakoids of aba1 produced twice as much 1O2 as thylakoids of max4 and wild type (WT) plants when illuminated with strong red light. 1O2 was measured using the spin probe 2,2,6,6-tetramethyl-4-piperidone hydrochloride. 77-K chlorophyll fluorescence emission spectra of thylakoids revealed lower aggregation of the light harvesting complex II in aba1. This was rationalized as a loss of connectivity between photosystem II (PSII) units and as the main cause for the high yield of 1O2 generation in aba1. Upregulation of the 1O2 responsive gene AAA-ATPase was only observed with statistical significant in aba1 under HL. Two early jasmonate (JA)-responsive genes, JAZ1 and JAZ5, encoding for two repressor proteins involved in the negative feedback regulation of JA signalling, were not up-regulated to the WT plant levels. Chloroplast aggregation followed by chloroplast rupture and eventual cell death was observed by confocal imaging of the fluorescence emission of leaf cells of transgenic aba1 plants expressing the chimeric fusion protein SSU-GFP. Cell death was not associated with direct 1O2 cytotoxicity in aba1, but rather with a delayed stress response. In contrast, max4 did not show evidence of 1O2-mediated cell death. In conclusion, aba1 may serve as an alternative model to other 1O2-overproducing mutants of Arabidopsis for investigating 1O2-mediated cell death

    Co-transcriptional degradation of aberrant pre-mRNA by Xrn2

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    Eukaryotic protein-coding genes are transcribed as pre-mRNAs that are matured by capping, splicing and cleavage and polyadenylation. Although human pre-mRNAs can be long and complex, containing multiple introns and many alternative processing sites, they are usually processed co-transcriptionally. Mistakes during nuclear mRNA maturation could lead to potentially harmful transcripts that are important to eliminate. However, the processes of human pre-mRNA degradation are not well characterised in the human nucleus. We have studied how aberrantly processed pre-mRNAs are degraded and find a role for the 5′→3′ exonuclease, Xrn2. Xrn2 associates with and co-transcriptionally degrades nascent β-globin transcripts, mutated to inhibit splicing or 3′ end processing. Importantly, we provide evidence that many endogenous pre-mRNAs are also co-transcriptionally degraded by Xrn2 when their processing is inhibited by Spliceostatin A. Our data therefore establish a previously unknown function for Xrn2 and an important further aspect of pre-mRNA metabolism that occurs co-transcriptionally

    Cryptic splicing events in the iron transporter ABCB7 and other key target genes in SF3B1-mutant myelodysplastic syndromes.

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    The splicing factor SF3B1 is the most frequently mutated gene in myelodysplastic syndromes (MDS), and is strongly associated with the presence of ring sideroblasts (RS). We have performed a systematic analysis of cryptic splicing abnormalities from RNA sequencing data on hematopoietic stem cells (HSCs) of SF3B1-mutant MDS cases with RS. Aberrant splicing events in many downstream target genes were identified and cryptic 3' splice site usage was a frequent event in SF3B1-mutant MDS. The iron transporter ABCB7 is a well-recognized candidate gene showing marked downregulation in MDS with RS. Our analysis unveiled aberrant ABCB7 splicing, due to usage of an alternative 3' splice site in MDS patient samples, giving rise to a premature termination codon in the ABCB7 mRNA. Treatment of cultured SF3B1-mutant MDS erythroblasts and a CRISPR/Cas9-generated SF3B1-mutant cell line with the nonsense-mediated decay (NMD) inhibitor cycloheximide showed that the aberrantly spliced ABCB7 transcript is targeted by NMD. We describe cryptic splicing events in the HSCs of SF3B1-mutant MDS, and our data support a model in which NMD-induced downregulation of the iron exporter ABCB7 mRNA transcript resulting from aberrant splicing caused by mutant SF3B1 underlies the increased mitochondrial iron accumulation found in MDS patients with RS

    HIF-driven SF3B1 induces KHK-C to enforce fructolysis and heart disease.

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    Fructose is a major component of dietary sugar and its overconsumption exacerbates key pathological features of metabolic syndrome. The central fructose-metabolising enzyme is ketohexokinase (KHK), which exists in two isoforms: KHK-A and KHK-C, generated through mutually exclusive alternative splicing of KHK pre-mRNAs. KHK-C displays superior affinity for fructose compared with KHK-A and is produced primarily in the liver, thus restricting fructose metabolism almost exclusively to this organ. Here we show that myocardial hypoxia actuates fructose metabolism in human and mouse models of pathological cardiac hypertrophy through hypoxia-inducible factor 1α (HIF1α) activation of SF3B1 and SF3B1-mediated splice switching of KHK-A to KHK-C. Heart-specific depletion of SF3B1 or genetic ablation of Khk, but not Khk-A alone, in mice, suppresses pathological stress-induced fructose metabolism, growth and contractile dysfunction, thus defining signalling components and molecular underpinnings of a fructose metabolism regulatory system crucial for pathological growth
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