Efficient sampling from truncated bivariate Gaussians via Box-Muller transformation

Many practical simulation tasks demand procedures to draw samples efficiently from multivariate truncated Gaussian distributions. In this work, we introduce a novel rejection approach, based on the Box-Muller transformation, to generate samples from a truncated bivariate Gaussian density with an arbitrary support. Furthermore, for an important class of support regions the new method allows us to achieve exact sampling, thus becoming the most efficient approach possible. RESUMEN. Método específico para generar muestras de manera eficiente de Gaussianas bidimensionales truncadas con cualquier zona de truncamiento basado en la transformación de Box-Muller.

Testament, 1661 nov. 20, en Sant Celoni, de Elisabét Pujadas, muller de Antoni Joan Pujadas, pagès de la parroquia de Sant Andreu de Vallgorguina, bisbat de Barcelona, ante el notario Miquel Bosch [Manuscrito]

Alcance y contenido: Testamento ms. de Isabel Pujadas (antes Mascaró), dejando como herederos a su marido, Antoni Joan Pujadas y a sus tres hermanos, Antich, Jacinto y Miquel Mascaró. Fue escrito en su propia casa y después trasladado a Sant Celoni para rubricarlo el notario

Coloqui nou molt curios y entretengut pera lo desfres de les Carnistoltes : [Texto impreso] en que un llaurador ab tota politica explica seriament a una dama el seu amor, y la demana per muller en grans termens y cortesia

Hay un ejemplar encuadernado con: Discret rahonament, quiexa formal que fan contra el Micalet de la Seu, la Torre de Espioca, y la Torre de Paterna, sobre la gran visita que éste tingué en lo dia cinc de Deembre [sic] ... per veure y admirar tan magnífica obra y deliciosa vista ... Carlos Quart (que Deu guart) y el señor Don Fernando de Borbó ... : (XVIII/1105).

Rahonament y coloqui nou en lo qual un Llaurador li declara son amora una dama chispera, procurant per molts camins el llograrla per muller, també li dona conte y raó de un festech que tingué en lo seu poble de Alfafar en la filla del Alcalde, y el raro motiu per que es desfeu [Texto impreso]

Hay un ejemplar encuadernado con: Discret rahonament, quiexa formal que fan contra el Micalet de la Seu, la Torre de Espioca, y la Torre de Paterna, sobre la gran visita que éste tingué en lo dia cinc de Deembre [sic] ... per veure y admirar tan magnífica obra y deliciosa vista ... Carlos Quart (que Deu guart) y el señor Don Fernando de Borbó ... : (XVIII/1105).

Rahonament y coloqui nou en lo qual un Llaurador li declara son amora una dama gispera, requebrantla per molts camins per veure si pot llograrla per muller, y al mateix temps li proposa son saber, manya, y habilitat [Texto impreso]

Hay un ejemplar encuadernado con: Discret rahonament, quiexa formal que fan contra el Micalet de la Seu, la Torre de Espioca, y la Torre de Paterna, sobre la gran visita que éste tingué en lo dia cinc de Deembre [sic] ... per veure y admirar tan magnífica obra y deliciosa vista ... Carlos Quart (que Deu guart) y el señor Don Fernando de Borbó ... : (XVIII/1105).

Abaristo, Peó de Obrer de Vila ó Manobre, y sa muller Doña Pepa Antonia la llabanera [Texto impreso] : ella vol Camisón, y tots los demés arreos de currutaca, y ell la persuadix á que no convé por razon de estado y falta de pesetes

Hay un ejemplar encuadernado con: Poesías colocadas en el pórtico del Convento de San Francisco de Valencia (NP849.91/3086).

Accelerated evolution and Muller's rachet in endosymbiotic bacteria.

Many bacteria live only within animal cells and infect hosts through cytoplasmic inheritance. These endosymbiotic lineages show distinctive population structure, with small population size and effectively no recombination. As a result, endosymbionts are expected to accumulate mildly deleterious mutations. If these constitute a substantial proportion of new mutations, endosymbionts will show (i) faster sequence evolution and (ii) a possible shift in base composition reflecting mutational bias. Analyses of 16S rDNA of five independently derived endosymbiont clades show, in every case, faster evolution in endosymbionts than in free-living relatives. For aphid endosymbionts (genus Buchnera), coding genes exhibit accelerated evolution and unusually low ratios of synonymous to nonsynonymous substitutions compared to ratios for the same genes for enterics. This concentration of the rate increase in nonsynonymous substitutions is expected under the hypothesis of increased fixation of deleterious mutations. Polypeptides for all Buchnera genes analyzed have accumulated amino acids with codon families rich in A+T, supporting the hypothesis that substitutions are deleterious in terms of polypeptide function. These observations are best explained as the result of Muller's ratchet within small asexual populations, combined with mutational bias. In light of this explanation, two observations reported earlier for Buchnera, the apparent loss of a repair gene and the overproduction of a chaperonin, may reflect compensatory evolution. An alternative hypothesis, involving selection on genomic base composition, is contradicted by the observation that the speedup is concentrated at nonsynonymous sites.

Muller's ratchet decreases fitness of a DNA-based microbe.

Muller proposed that an asexual organism will inevitably accumulate deleterious mutations, resulting in an increase of the mutational load and an inexorable, ratchet-like, loss of the least mutated class [Muller, H.J. (1964) Mutat. Res. 1, 2-9]. The operation of Muller's ratchet on real populations has been experimentally demonstrated only in RNA viruses. However, these cases are exceptional in that the mutation rates of the RNA viruses are extremely high. We have examined whether Muller's ratchet operates in Salmonella typhimurium, a DNA-based organism with a more typical genomic mutation rate. Cells were grown asexually under conditions expected to result in high genetic drift, and the increase in mutational load was determined. S. typhimurium accumulated mutations under these conditions such that after 1700 generations, 1% of the 444 lineages tested had suffered an obvious loss of fitness, as determined by decreased growth rate. These results suggest that in the absence of sex and with high genetic drift, genetic mechanisms, such as back or compensatory mutations, cannot compensate for the accumulation of deleterious mutations. In addition, we measured the appearance of auxotrophs, which allowed us to calculate an average spontaneous mutation rate of approximately 0.3-1.5 x 10(-9) mutations per base pair per generation. This rate is measured for the largest genetic target studied so far, a collection of about 200 genes.

Protaetia (Eupotosia) affinis (Andersch, 1797) y Protaetia (Eupotosia) mirifica (Mulsant, 1842) en el sudoeste de la provincia de Salamanca (Coleoptera: Scarabaeoidea: Cetoniidae, Cetoniini)

Esta investigación fue financiada en parte por el Ministerio de Ciencia e Innovación (CGL2011-23658), Ministerio de Economía y Competitividad (CGL2012-31669) y Generalitat Valenciana (proyectos PROMETEO/2013/03412 y ACOMP/2014/140). A. R. H. agradece la beca predoctoral del programa Santiago Grisolía de la Generalitat Valenciana (GRISOLIA/2010/080).