The Heterotic Dyonic Instanton

The static Yang-Mills-Higgs dyonic instanton is shown to have a non-vanishing, but anti-self-dual, angular momentum 2-form with skew eigenvalues equal to the electric charge; for large charge the angular momentum causes the instanton to expand into a hyper-spherical shell. A class of exact multi dyonic instantons is then found and then generalized to a new class of 1/4 supersymmetric, non-singular, stationary, exact solutions of the ten-dimensional supergravity/Yang-Mills theory. These self-gravitating dyonic instantons yield new heterotic string solitons, to leading order in the inverse string tension.Comment: 18 pages, LaTeX, no figures. Previous revision was to include exact multi-solitons. Third version corrects typos and ADM energy formul

Non-BPS Branes in a Type I Orbifold

We analyse the spectrum of non-BPS branes in the type I theory on the orbifold $T^4/{\cal I}_4$. We present a detailed analysis of the action of the worldsheet parity $\Omega$ on the different D-brane boundary state sectors of type IIB on $T^4/{\cal I}_4$, using the covariant formulation. Using these results we derive the spectrum of branes in the type I orbifold. We find $\Z_2$- and $\Z$- charged non-BPS branes. A study of the stability of these branes in the type I orbifold is also presented. We find that the type I non-BPS D-particle and D-instanton remain stable in the orbifold. The D-particle carries no charge whereas the non-BPS D-instanton can carry twisted R-R charge.Comment: 32 pages, LaTeX, no figures. Stability analysis has been corrected: the D-particle is found to be stabl

Spacetime-Filling Branes and Strings with Sixteen Supercharges

We discuss branes whose worldvolume dimension equals the target spacetime dimension, i.e. ``spacetime-filling branes''. In addition to the D9-branes, there are 9-branes in the NS-NS sectors of both the IIA and IIB strings. The worldvolume actions of these branes are constructed, via duality, from the known actions of branes with codimension larger than zero. Each of these types of branes is used in the construction of a string theory with sixteen supercharges by modding out a type II string by an appropriate discrete symmetry and adding 32 9-branes. These constructions are related by a web of dualities and each arises as a different limit of the Horava-Witten construction.Comment: 43 pages, LaTeX, 8 figures, uses html.sty, version to appear in Nucl. Phys.

T-duality and Actions for Non-BPS D-branes

We employ T-duality to restrict the tachyon dependence of effective actions for non-BPS D-branes. For the Born-Infeld part the criteria of T-duality and supersymmetry are satisfied by a simple extension of the D-brane Born-Infeld action.Comment: Latex, 11 page

Herramienta para estimación de generación fotovoltaica en edificaciones e integración arquitectónica

Se presenta en este trabajo una herramienta didáctica destinada a proyectistas e instaladores que disponen sus sistemas solares fotovoltaicos sobre azoteas de edificios, cubiertas inclinadas y sobre otras superficies edilicias o no. Dichas superficies no siempre posibilitan una perfecta inclinación y orientación de los arreglos de paneles para lograr la máxima generación que el equipo permite. A través de un poliedro de generación solar es posible estimar de manera rápida, sencilla y con un bajo grado de error, la energía disponible para instalar estos equipos en edificios ubicados en los principales centros urbanos de la República Argentina y en diferentes inclinaciones y orientaciones distintas de la ideal. Esta herramienta también puede resultar de utilidad para aquellos ciudadanos interesados en realizar estimaciones de generación fotovoltaica en instalaciones dentro de la normativa de generación distribuida actual.In residential photovoltaic systems, teachers, designers and installers, usually work with different tools to estimate the annual energy production. The objective of this article is to present a new simple tool which can be used not only for teaching but also by designers and installers. Photovoltaic systems lay over rooftops, sloping roofs and others building surfaces. These surfaces may not allow a perfect slope or orientation for the solar panels to obtain the maximum energy production. Using a polyhedron of solar energy production, it is possible to estimate the energy production of a system in a fast and easy way with low error ratio. This tool is intended to be used in the main urban centers in Argentine. In addition, it could be useful in promotion and outreach addressed to citizens who are in the process of buying a photovoltaic system under the new law of distributed energy generation.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Instantonic dyons of Yang-Mills--Chern-Simons models in d=2n+1 dimensions, n>2

We investigate finite energy solutions of Yang-Mills--Chern-Simons systems in odd spacetime dimensions, d=2n+1, with n>2. This can be carried out systematically for all n, but the cases n=3,4 corresponding to a 7,8 dimensional spacetime are treated concretely. These are static and spherically symmetric configurations, defined in a flat Minkowski background. The value of the electric charge is fixed by the Chern-Simons coupling constant.Comment: 15 pages, 4 figure

Gauged supergravity from dimensional reduction

We perform a generalised Scherk-Schwarz reduction of the effective action of the heterotic string on T6 to obtain a massive N = 4 supergravity theory in four dimensions. The local symmetry-group of the resulting d = 4 theory includes a Heisenberg group, which is a subgroup of the global 0(6,6 + n) obtained in the standard reduction. We show explicitly that the same theory can be obtained by gauging this Heisenberg group in d = 4, N = 4 supergravity.

Systematic benchmarking of tools for CpG methylation detection from nanopore sequencing

DNA methylation plays a fundamental role in the control of gene expression and genome integrity. Although there are multiple tools that enable its detection from Nanopore sequencing, their accuracy remains largely unknown. Here, we present a systematic benchmarking of tools for the detection of CpG methylation from Nanopore sequencing using individual reads, control mixtures of methylated and unmethylated reads, and bisulfite sequencing. We found that tools have a tradeoff between false positives and false negatives and present a high dispersion with respect to the expected methylation frequency values. We described various strategies to improve the accuracy of these tools, including a consensus approach, METEORE ( https://github.com/comprna/METEORE ), based on the combination of the predictions from two or more tools that shows improved accuracy over individual tools. Snakemake pipelines are also provided for reproducibility and to enable the systematic application of our analyses to other datasets

Chromatin and alternative splicing

Alternative splicing affects more than 90% of human genes. Coupling between transcription and splicing has become crucial in the complex network underlying alternative splicing regulation. Because chromatin is the real template for nuclear transcription, changes in its structure, but also in the "reading" and "writing" of the histone code, could modulate splicing choices. Here, we discuss the evidence supporting these ideas, from the first proposal of chromatin affecting alternative splicing, performed 20 years ago, to the latest findings including genome-wide evidence that nucleosomes are preferentially positioned in exons. We focus on two recent reports from our laboratories that add new evidence to this field. The first report shows that a physiological stimulus such as neuron depolarization promotes intragenic histone acetylation (H3K9ac) and chromatin relaxation, causing the skipping of exon 18 of the neural cell adhesion molecule gene. In the second report, we show how specific histone modifications can be created at targeted gene regions as a way to affect alternative splicing: Using small interfering RNAs (siRNAs), we increased the levels of H3K9me2 and H3K27me3 in the proximity of alternative exon 33 of the human fibronectin gene, favoring its inclusion into mature messenger RNA (mRNA) through a mechanism that recalls RNAmediated transcriptional gene silencing. © 2010 Cold Spring Harbor Laboratory Press.Fil:Alló, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Schor, I.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Muñoz, M.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:De La Mata, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Kornblihtt, A.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina