76 research outputs found
Problemática del txistu
El txistu, nuestro tÃpico y ancestral instrumento, sÃmbolo del sentir musical del pueblo vasco, Ãntimamente unido a su desarrollo, ha adquirido gran popularidad a través de las melodÃas ejecutadas por txistularis en romerÃas, danzas populares pero existe un escaso conocimiento del txistu de concierto. Actualmente se está llevando a cabo un movimiento de renovación del ambiente txistulari (mejora técnica de los instrumentos, aumento de la familia instrumental del txistu). El aspecto pedagógico del txistu necesita una estructuración urgente en sus sistemas y enseñanzas. El txistu puede servir a nuestra música de muy diversas formas. El rústico txistu se adentra en el terreno experimental con una doble problemática: técnica y emocional (adaptando nuestra mentalidad ante los aires renovadores del instrumento). Ha llegado la hora de apreciar nuevas sonoridades, técnicas nuevas, concertar el txistu con otros instrumentos, componer partituras originales, perfeccionar a los alumnos txistularis. El mantenimiento y progreso del txistu compete a todo
Uncovering Proximity of Chromosome Territories using Classical Algebraic Statistics
Exchange type chromosome aberrations (ETCAs) are rearrangements of the genome
that occur when chromosomes break and the resulting fragments rejoin with other
fragments from other chromosomes. ETCAs are commonly observed in cancer cells
and in cells exposed to radiation. The frequency of these chromosome
rearrangements is correlated with their spatial proximity, therefore it can be
used to infer the three dimensional organization of the genome. Extracting
statistical significance of spatial proximity from cancer and radiation data
has remained somewhat elusive because of the sparsity of the data. We here
propose a new approach to study the three dimensional organization of the
genome using algebraic statistics. We test our method on a published data set
of irradiated human blood lymphocyte cells. We provide a rigorous method for
testing the overall organization of the genome, and in agreement with previous
results we find a random relative positioning of chromosomes with the exception
of the chromosome pairs \{1,22\} and \{13,14\} that have a significantly larger
number of ETCAs than the rest of the chromosome pairs suggesting their spatial
proximity. We conclude that algebraic methods can successfully be used to
analyze genetic data and have potential applications to larger and more complex
data sets
A Liquid Crystal Model of Viral DNA Encapsidation
A liquid crystal continuum modeling framework for icosahedra bacteriophage
viruses is developed and tested. The main assumptions of the model are the
chromonic columnar hexagonal structure of confined DNA, the high resistance to
bending and the phase transition from solid to fluid-like states as the
concentration of DNA in the capsid decreases during infection. The model
predicts osmotic pressure inside the capsid and the ejection force of the DNA
as well as the size of the isotropic volume at the center of the capsid.
Extensions of the model are discussed
Fine Structure of Viral dsDNA Encapsidation
In vivo configurations of dsDNA of bacteriophage viruses in a capsid are
known to form hexagonal chromonic liquid crystal phases. This article studies
the liquid crystal ordering of viral dsDNA in an icosahedral capsid, combining
the chromonic model with that of liquid crystals with variable degree of
orientation. The scalar order parameter of the latter allows us to distinguish
regions of the capsid with well-ordered DNA from the disordered central core.
We employ a state-of-the-art numerical algorithm based on the finite element
method to find equilibrium states of the encapsidated DNA and calculate the
corresponding pressure. With a data-oriented parameter selection strategy, the
method yields phase spaces of the pressure and the radius of the disordered
core, in terms of relevant dimensionless parameters, rendering the proposed
algorithm into a preliminary bacteriophage designing tool. The presence of the
order parameter also has the unique role of allowing for non-smooth capsid
domains as well as accounting for knot locations of the DNA
Topology of viral DNA
Chromosome organization plays a key role in many biological processes. In viruses genome organization is essential for the packaging and releasing of the genome as well as for maintaining the stability of the viral capsid. This organization varies across different families and is highly dependent on the virus morphogenetic pathway (Casjens, 1997). In this review we will focus on the packing of double stranded DNA (dsDNA) in bacteriophages.
Understanding how dsDNA is packed in bacteriophage capsids is important because it arguably yields the simplest example of a full genome organization in a biological system. Furthermore bacteriophages are believed to pack their DNA similarly to some animal viruses such as herpes and adeno-viruses (Casjens, 1997). Therefore understanding the basic principles of DNA packing in bacteriophages may provide essential insights into the viral assembly pathways for a wide range of bacterial and animal viruses.J. Arsuaga is supported by NIH grant 2S06GM52588–12.Peer Reviewe
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The Rabl configuration limits topological entanglement of chromosomes in budding yeast.
The three dimensional organization of genomes remains mostly unknown due to their high degree of condensation. Biophysical studies predict that condensation promotes the topological entanglement of chromatin fibers and the inhibition of function. How organisms balance between functionally active genomes and a high degree of condensation remains to be determined. Here we hypothesize that the Rabl configuration, characterized by the attachment of centromeres and telomeres to the nuclear envelope, helps to reduce the topological entanglement of chromosomes. To test this hypothesis we developed a novel method to quantify chromosome entanglement complexity in 3D reconstructions obtained from Chromosome Conformation Capture (CCC) data. Applying this method to published data of the yeast genome, we show that computational models implementing the attachment of telomeres or centromeres alone are not sufficient to obtain the reduced entanglement complexity observed in 3D reconstructions. It is only when the centromeres and telomeres are attached to the nuclear envelope (i.e. the Rabl configuration) that the complexity of entanglement of the genome is comparable to that of the 3D reconstructions. We therefore suggest that the Rabl configuration is an essential player in the simplification of the entanglement of chromatin fibers
Orientation of DNA Minicircles Balances Density and Topological Complexity in Kinetoplast DNA
Kinetoplast DNA (kDNA), a unique mitochondrial structure common to trypanosomatid parasites, contains thousands of DNA minicircles that are densely packed and can be topologically linked into a chain mail-like network. Experimental data indicate that every minicircle in the network is, on average, singly linked to three other minicircles (i.e., has mean valence 3) before replication and to six minicircles in the late stages of replication. The biophysical factors that determine the topology of the network and its changes during the cell cycle remain unknown. Using a mathematical modeling approach, we previously showed that volume confinement alone can drive the formation of the network and that it induces a linear relationship between mean valence and minicircle density. Our modeling also predicted a minicircle valence two orders of magnitude greater than that observed in kDNA. To determine the factors that contribute to this discrepancy we systematically analyzed the relationship between the topological properties of the network (i.e., minicircle density and mean valence) and its biophysical properties such as DNA bending, electrostatic repulsion, and minicircle relative position and orientation. Significantly, our results showed that most of the discrepancy between the theoretical and experimental observations can be accounted for by the orientation of the minicircles with volume exclusion due to electrostatic interactions and DNA bending playing smaller roles. Our results are in agreement with the three dimensional kDNA organization model, initially proposed by Delain and Riou, in which minicircles are oriented almost perpendicular to the horizontal plane of the kDNA disk. We suggest that while minicircle confinement drives the formation of kDNA networks, it is minicircle orientation that regulates the topological complexity of the network
Sobre la situación de los servicios psiquiátricos de la provincia de Alicante.
Con motivo de la solicitud realizada por un grupo de profesionales de los servicios psiquiátricos de la Diputación de Alicante, en la que señalaban una serie de dificultades en el proceso de integración y reforma de la salud mental, la Junta Directiva de la AEN acordó formar una comisión que se desplazase a Alicante con objeto de valorar, sobre el terreno, la situación de dichos servicios. Dos miembros de la Comisión de Asistencia nos desplazamos a Alicante y Valencia para intentar conocer directamente el funcionamiento de los servicios y mantener varias entrevistas con todas las partes relacionadas con los mismos
Sobre la situación de los servicios psiquiátricos de la provincia de Alicante.
Con motivo de la solicitud realizada por un grupo de profesionales de los servicios psiquiátricos de la Diputación de Alicante, en la que señalaban una serie de dificultades en el proceso de integración y reforma de la salud mental, la Junta Directiva de la AEN acordó formar una comisión que se desplazase a Alicante con objeto de valorar, sobre el terreno, la situación de dichos servicios. Dos miembros de la Comisión de Asistencia nos desplazamos a Alicante y Valencia para intentar conocer directamente el funcionamiento de los servicios y mantener varias entrevistas con todas las partes relacionadas con los mismos
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