A magnified glance into the dark sector: probing cosmological models with strong lensing in A1689

In this paper we constrain four alternative models to the late cosmic acceleration in the Universe: Chevallier-Polarski-Linder (CPL), interacting dark energy (IDE), Ricci holographic dark energy (HDE), and modified polytropic Cardassian (MPC). Strong lensing (SL) images of background galaxies produced by the galaxy cluster Abell $1689$ are used to test these models. To perform this analysis we modify the LENSTOOL lens modeling code. The value added by this probe is compared with other complementary probes: Type Ia supernovae (SNIa), baryon acoustic oscillations (BAO), and cosmic microwave background (CMB). We found that the CPL constraints obtained of the SL data are consistent with those estimated using the other probes. The IDE constraints are consistent with the complementary bounds only if large errors in the SL measurements are considered. The Ricci HDE and MPC constraints are weak but they are similar to the BAO, SNIa and CMB estimations. We also compute the figure-of-merit as a tool to quantify the goodness of fit of the data. Our results suggest that the SL method provides statistically significant constraints on the CPL parameters but weak for those of the other models. Finally, we show that the use of the SL measurements in galaxy clusters is a promising and powerful technique to constrain cosmological models. The advantage of this method is that cosmological parameters are estimated by modelling the SL features for each underlying cosmology. These estimations could be further improved by SL constraints coming from other galaxy clusters.Comment: 13 pages, 5 figures, accepted for publication in Ap

Probing the dynamical and X-ray mass proxies of the cluster of galaxies Abell S1101

Context: The galaxy cluster Abell S1101 (S1101 hereafter) deviates significantly from the X-ray luminosity versus velocity dispersion relation (L-sigma) of galaxy clusters in our previous study. Given reliable X-ray luminosity measurement combining XMM-Newton and ROSAT, this could most likely be caused by the bias in the velocity dispersion due to interlopers and low member statistic in the previous sample of member galaxies, which was solely based on 20 galaxy redshifts drawn from the literature. Aims: We intend to increase the galaxy member statistic to perform a precision measurement of the velocity dispersion and dynamical mass of S1101. We aim for a detailed substructure and dynamical state characterization of this cluster, and a comparison of mass estimates derived from (i) the velocity dispersion (M_vir), (ii) the caustic mass computation (M_caustic), and (iii) mass proxies from X-ray observations and the Sunyaev-Zeldovich (SZ) effect. Methods: We carried out new optical spectroscopic observations of the galaxies in this cluster field with VIMOS, obtaining a sample of ~60 member galaxies for S1101. We revised the cluster redshift and velocity dispersion measurements based on this sample and also applied the Dressler-Shectman substructure test. Results: The completeness of cluster members within r200 was significantly improved for this cluster. Tests for dynamical substructure did not show evidence for major disturbances or merging activities in S1101. We find good agreement between the dynamical cluster mass measurements and X-ray mass estimates which confirms the relaxed state of the cluster displayed in the 2D substructure test. The SZ mass proxy is slightly higher than the other estimates. The updated measurement of the velocity dispersion erased the deviation of S1101 in the L-sigma relation.Comment: 17 pages, 7 figures, 5 table

Phenological cycle and floral development of Chloraea crispa (Orchidaceae)

Vogel, H (Vogel, Hermine).Univ Talca, Fac Ciencias Agr, Talca, ChileU. Steinfort, M.A. Cisternas, R. Garcia, H. Vogel, and G. Verdugo. 2012. Phenological cycle and floral development of Chloraea crispa (Orchidaceae). Cien. Inv. Agr. 39(2): 377-385. Chloraea crispa Lindl. is a terrestrial orchid endemic to Chile that has potential to be a novel alternative for the cut flower industry. The objectives of this study were to describe the phenological cycle and floral bud development of C. crispa to determine the timing of initiation and differentiation of the spike. During the summer, plants are dormant. The renewal buds are located at the top of the rhizome, next to the buds from which the shoot of the previous season originated. From the end of summer until the end of winter, the plant is in vegetative growth. From June onward, the flower stalk starts to emerge, and flowering and leaf senescence occur during the spring until the beginning of summer. The renewal buds started forming leaf primordia during or after the flowering of the above-ground annual stems and the senescence of the plant. Between December and January, the apical meristem changes to the reproductive stage, and from March, the first flower primordial could be observed. C. crispa shows similarity with other geophytes in which florogenesis and the development of new organs occurs within the renewal buds during or after the summer dormancy period

Multiwavelength Study of NGC 281 Region

We present a multiwavelength study of the NGC 281 complex which contains the young cluster IC 1590 at the center, using deep wide-field optical UBVI_c photometry, slitless spectroscopy along with archival data sets in the near-infrared (NIR) and X-ray. The extent of IC 1590 is estimated to be ~6.5 pc. The cluster region shows a relatively small amount of differential reddening. The majority of the identified young stellar objects (YSOs) are low mass PMS stars having age <1-2 Myr and mass 0.5-3.5 M_\odot. The slope (\Gamma) of the mass function for IC 1590, in the mass range 2 < M/M_\odot \le 54, is found to be -1.11+-0.15. The slope of the K-band luminosity function (0.37+-0.07) is similar to the average value (~0.4) reported for young clusters. The distribution of gas and dust obtained from the IRAS, CO and radio maps indicates clumpy structures around the central cluster. The radial distribution of the young stellar objects, their ages, \Delta(H-K) NIR-excess, and the fraction of classical T Tauri stars suggest triggered star formation at the periphery of the cluster region. However, deeper optical, NIR and MIR observations are needed to have a conclusive view of star formation scenario in the region. The properties of the Class 0/I and Class II sources detected by using the Spitzer mid-infrared observations indicate that a majority of the Class II sources are X-ray emitting stars, whereas X-ray emission is absent from the Class 0/I sources. The spatial distribution of Class 0/I and Class II sources reveals the presence of three sub-clusters in the NGC 281 West region.Comment: 29 pages, 21 figures and 11 tables, Accepted for the publication in PAS

Capacidad predictiva de la P.A.A. en el rendimiento universitario para los alumnos de primer ano de la Universidad de Talca

136 p.La Prueba de Aptitud Académica (P.A.A.) ha sido objeto de múltiples cuestionamientos acerca de su efectividad como instrumento de medición, en este contexto quisimos preguntarnos en que grado esta prueba seria capaz de predecir el rendimiento académico de los postulantes a la educación superior. En nuestro estudio se quiso analizar econométricamente la capacidad predictiva de dicha prueba. Para ello utilizamos como metodología de trabajo, el modelo de Regresión Múltiple. Se escogió como muestra a los alumnos que ingresaron vía P.A.A. a la Universidad de Talca entre los anos 1993 a 1997, considerando solo el primer ano académico para las carreras que poseían ingresos continuos durante el periodo en estudio. Para el análisis de regresión se definió como variable dependiente o explicada, el rendimiento académico medido a través de una formula basada en el concepto de Puntaje de Prioridad que actualmente utiliza la Facultad de Ciencias Económicas y Administrativas de la Universidad de Chile. Las variables independientes o explicativas estarán dadas por las pruebas obligatorias que componen la P.A.A y las Notas de Enseñanza Media. En primera instancia, observamos que no existía correlación entre las variables y no fue posible explicar el comportamiento del rendimiento académico a través de las variables independientes. Para ratificar nuestros resultados, se selecciono una nueva muestra que incluyera no solo el primer ano sino tres anos académicos, de manera de descartar la posible aleatoriedad del comportamiento del rendimiento en primer nivel. Sin embargo, nuevamente se obtuvieron los mismos resultados

Resultados generales

Aspecto externo Morfometría esquelética y masa Morfometría alar y caudal Tamaño Estructuras sexuales externas Determinación del sexo Neumatización craneal Muda Datación mediante variables semicuantitativas Ciclos vitale

Serious limitations of the QTL/Microarray approach for QTL gene discovery

<p>Abstract</p> <p>Background</p> <p>It has been proposed that the use of gene expression microarrays in nonrecombinant parental or congenic strains can accelerate the process of isolating individual genes underlying quantitative trait loci (QTL). However, the effectiveness of this approach has not been assessed.</p> <p>Results</p> <p>Thirty-seven studies that have implemented the QTL/microarray approach in rodents were reviewed. About 30% of studies showed enrichment for QTL candidates, mostly in comparisons<b/> between congenic and background strains. Three studies led to the identification of an underlying <it>QTL </it>gene. To complement the literature results, a microarray experiment was performed using three mouse congenic strains isolating the effects of at least 25 biometric QTL. Results show that genes in the congenic donor regions were preferentially selected. However, within donor regions, the distribution of differentially expressed genes was homogeneous once gene density was accounted for. Genes within identical-by-descent (IBD) regions were less likely to be differentially expressed in chromosome 2, but not in chromosomes 11 and 17. Furthermore, expression of <it>QTL </it>regulated in <it>cis </it>(<it>cis </it>eQTL) showed higher expression in the background genotype, which was partially explained by the presence of single nucleotide polymorphisms (SNP).</p> <p>Conclusions</p> <p>The literature shows limited successes from the QTL/microarray approach to identify <it>QTL </it>genes. Our own results from microarray profiling of three congenic strains revealed a strong tendency to select <it>cis-</it>eQTL over <it>trans-</it>eQTL. IBD regions had little effect on rate of differential expression, and we provide several reasons why IBD should not be used to discard eQTL candidates. In addition, mismatch probes produced false <it>cis-</it>eQTL that could not be completely removed with the current strains genotypes and low probe density microarrays. The reviewed studies did not account for lack of coverage from the platforms used and therefore removed genes that were not tested. Together, our results explain the tendency to report QTL candidates as differentially expressed and indicate that the utility of the QTL/microarray as currently implemented is limited. Alternatives are proposed that make use of microarray data from multiple experiments to overcome the outlined limitations.</p

Fichas de las especies

Sittasomus griseicapillus, Xiphorhynchus flavigaster, Myiopagis viridicata, Mitrephanes phaeocercus, Empidonax difficilis / occidentalis, Myiarchus tuberculifer, Myiarchus cinerascens, Myiarchus nuttingi, Myiarchus tyrannulus, Pitangus sulphuratus, Myiozetetes similis, Myiodynastes luteiventris, Pachyramphus aglaiae, Vireo brevipennis, Vireo bellii, Vireo nelsoni, Vireo hypochryseus, Vireo gilvus, Vireo flavoviridis, Thryothorus sinaloa, Thryothorus felix, Troglodytes brunneicollis, Troglodytes aedon, Henicorhina leucophrys, Polioptila caerulea, Myadestes occidentalis, Catharus aurantiirostris, Catharus occidentalis, Catharus frantzii, Catharus ustulatus, Turdus assimilis, Turdus rufopalliatus, Melanotis caerulescens, Vermivora celata, Vermivora ruficapilla, Vermivora crissalis, Parula superciliosa, Parula pitiayumi, Dendroica petechia, Dendroica coronata, Dendroica nigrescens, Dendroica townsendi, Dendroica graciae, Mniotilta varia, Seiurus aurocapilla, Seiurus noveboracensis, Seiurus motacilla, Oporornis tolmiei, Geothlypis trichas, Geothlypis poliocephala, Wilsonia pusilla, Cardellina rubrifrons, Myioborus miniatus, Basileuterus belli, Icteria virens, Granatellus venustus Piranga erythrocephala, Volatinia jacarina, Diglossa baritula, Atlapetes pileatus, Arremon virenticeps Arremonops rufivirgatus, Melozone kieneri, Pipilo ocai, Aimophila ruficauda, Melospiza lincolnii Saltator coerulescens, Pheucticus melanocephalus, Cyanocompsa parellina, Passerina leclancherii, Passerina versicolor, Passerina ciris, Icterus cucullatus, Icterus pustulatus, Icterus graduacauda Carduelis notat

ALMA resolves molecular clouds in the metal poor Magellanic Bridge A

(Abridged)We characterize gas and dust emission in Magellanic Bridge A, which has the highest 870$\mu$m excess of emission found in single dish surveys. Using the ALMA telescope, we mapped the Magellanic Bridge A molecular cloud with sub-parsec resolution, in 1.3 mm continuum and CO(2-1) line emission. We also map the cloud in 870$\mu$m continuum and CO(2-1) line emission at ~6 pc resolution with APEX. We combine the ALMA and APEX CO(2-1) line cubes to study the molecular gas emission. Magellanic Bridge A breaks up into two distinct molecular clouds in dust and CO(2-1) emission, which we call North and South. Dust emission in the North source, according to our best parameters from fitting the far-infrarred fluxes, is ~3 K colder than in the South source in correspondence to its less developed star formation. Both dust sources present large submillimeter excesses in LABOCA data: according to our best fits the excess over the modified blackbody (MBB) fit to the Spitzer/Herschel continuum are ~7 and ~3 for the North and South sources respectively. Nonetheless, we do not detect the corresponding 1.3 mm continuum with ALMA. Our limits are compatible with the extrapolation of the MBB fits and therefore we cannot independently confirm the excess at this longer wavelength. The CO(2-1) emission is in two parsec-sized clouds with virial masses around 400 and 700 Mo each. Their volume densities are ~700-2600 cm$^{-3}$, larger than typical bulk densities of Galactic molecular clouds. The CO-to-H2 conversion factor is 6.5 and 15 M$_{\odot}$ (K km s$^{-1}$ pc$^2$)$^{-1}$ for the North and South clouds, calculated using their respective virial masses and CO(2-1) luminosities. Gas mass estimates from our MBB fits to dust emission yields masses $M\sim1.3\times10^3$ M$_{\odot}$ and $2.9\times10^3$ M$_{\odot}$ for North and South respectively, a factor ~4 larger than the virial masses we infer from CO.Comment: Astronomy & Astrophysics in press. 14 pages, 6 figures, 7 table