52 research outputs found

    The HIHI- and H2H_{2}-to-stellar mass correlations of late- and early-type galaxies and their consistency with the observational mass functions

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    We compile and carrefully homogenize local galaxy samples with available information on stellar, HI\rm HI and/or H2\rm H_{2} masses, and morphology. After processing the information on upper limits in the case of non gas detections, we determine the HI\rm HI- and H2\rm H_{2}-to-stellar mass relations and their 1σ1\sigma scatter for both late- and early-type galaxies. The obtained relations are fitted to single or double power laws. Late-type galaxies are significantly gas richer than early-type ones, specially at high masses. The respective H2\rm H_{2}-to-HI\rm HI mass ratios as a function of MM_{\ast} are discussed. Further, we constrain the full mass-dependent distribution functions of the HI\rm HI- and H2\rm H_{2}-to-stellar mass ratios. We find that they can be described by a Schechter function for late types and a (broken) Schechter + uniform function for early types. By using the observed galaxy stellar mass function and the volume-complete late-to-early-type galaxy ratio as a function of MM_{\ast}, these empirical distribution functions are mapped into HI\rm HI and H2\rm H_{2} mass functions. The obtained mass functions are consistent with those inferred from large surveys. The empirical gas-to-stellar mass relations and their distributions for local late- and early-type galaxies presented here can be used to constrain models and simulations of galaxy evolution.Comment: 43 pages, 18 figures, to appear in RMxAA. Minor corrections introduced. The presented results are optimal for comparisons with theoretical predictions. Py-code to generate the HI- and H2-to-stellar mass relations and their 1sigma scatter, as well as the full mass-dependent distribution functions of the MHI/Ms and MH2/Ms ratios are available upon request to A.R. Calett

    U B V R I Photometry of Stellar Structures throughout the Disk of the Barred Galaxy NGC 3367

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    We report new detailed surface U, B, V, R, and I photometry of 81 stellar structures in the disk of the barred galaxy NGC 3367. The images show many different structures indicating that star formation is going on in the most part of the disk. NGC 3367 is known to have a very high concentration of molecular gas distribution in the central regions of the galaxy and bipolar synchrotron emission from the nucleus with two lobes (at 6 kpc) forming a triple structure similar to a radio galaxy. We have determined the U, B, V, R, and I magnitudes and U - B, B - V, U - V, and V - I colors for the central region (nucleus), a region which includes supernovae 2003 AA, and 79 star associations throughout NGC 3367. Estimation of ages of star associations is very difficult due to several factors, among them: filling factor, metallicity, spatial distribution of each structure and the fact that we estimated the magnitudes with a circular aperture of 16 pixels in diameter, equivalent to 6.81.46''.8\sim1.4 kpc. However, if the colors derived for NGC 3367 were similar to the colors expected of star clusters with theoretical evolutionary star tracks developed for the LMC and had a similar metallicity, NGC 3367 show 51 percent of the observed structures with age type SWB I (few tens of Myrs), with seven sources outside the bright surface brightness visible disk of NGC 3367.Comment: Accepted for publication (abr 2007) in The Astronomical Journal (July 2007 issue

    Assessment of interests and cognitive styles of learning in science in students 7th and 8th years of teaching basic and 1st and 2nd of teaching secondary in the province of Llanquihue

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    El interés por estudiar ciencia en nuestro país debe ser abordado bajo nuevos modelos didácticos curriculares, que estén relacionados con el entorno y con el desarrollo económico social de la región, de tal forma que los estudiantes se puedan ver más motivados y encuentren el sentido de vida que tiene la ciencia. Se evaluaron los intereses y estilos cognitivos de aprendizaje en ciencia en alumnos de séptimo y octavo Básico y primero y segundo año de Educación Media de la Provincia de Llanquihue, Región de los Lagos, Chile. La muestra estuvo compuesta por 80 alumnos seleccionados de un colegio Particular, uno Particular Subvencionado, uno de Educación General Básica Municipalizado y un colegio Técnico Profesional Municipalizado. Se evaluaron los intereses vocacionales a través del test de Kuder y los estilos de aprendizaje con el test de Honey –Alonso. Todos los colegios están sobre el 60% de actitud positiva hacia el aprendizaje de la ciencia, pero la contextualización no se ve inserta en el tratamiento de los contenidos.The interest for studying science in our country should considerate a new didactic approach and a new curricular model, related to the environment and to the regional social economical development, in order to motivate students and help them to find the sense of life through science. The samples utilized in this research were: a private school, a semi- private school, a primary public school and a public vocational school. The results show that 60% of students have a positive attitude towards the science learning. However, contextualization in the science teaching is not noticed

    A novel HPV 16 L1-based chimeric virus-like particle containing E6 and E7 seroreactive epitopes permits highly specific detection of antibodies in patients with CIN 1 and HPV-16 infection

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    <p>Abstract</p> <p>Background</p> <p>The presence of IgG antibodies to HPV-16 L1-virus like particles (VLPs) in serum has been reported as a result of persistent exposure to the virus and as a marker of disease progression. However, detection of VLP-specific antibodies in sera does not always indicate a malignant lesion as positive results may also be due to a nonmalignant viral infection. Furthermore, malignant lesions are associated with an increased antibody titer for E6 and E7 proteins. The aim of this study was to develop an ELISA using a novel chimeric virus-like particle (cVLP) encoding an L1 protein fused with a string of HPV-16 E6 and E7 seroreactive epitopes to its C-terminus to be used for detection of HPV-16 specific antibodies in patients with cervical intraepithelial lesion grade 1 (CIN 1).</p> <p>Results</p> <p>The sera of 30 patients with CIN 1 who also tested positive for HPV-16 DNA and of 30 age-matched normal donors negative for HPV infection were tested for the presence of IgG antibodies specific for either VLP-L1 (HPV-16 L1), gVLP (derived from Gardasil), or cVLP by ELISA. The cVLP-reactive sera yielded two distinct groups of results: (H) reactivity levels that presented very strong cVLP-specific titers, and (L) reactivity levels with significantly lower titers similar to those obtained with VLP-L1 and gVLP antigens. Additionally, the sera that presented the higher cVLP titers closely matched those that had significantly stronger reactivity to E6 and E7 epitopes. Interestingly, the samples with the highest titers corresponded to patients with the higher numbers of sexual partners and pregnancies. On the other hand only 4 out of the 12 sera that harbored antibodies with VLP neutralizing ability corresponded to the group with high cVLP antibody titers.</p> <p>Conclusion</p> <p>We report for the first time that chimeric particles containing HPV-16 L1 protein fused with E6 and E7 seroreactive epitopes enable much better detection of IgG antibodies in the sera of CIN 1 patients positive for HPV-16 infection than those obtained with VLPs containing only the HPV-16 L1 protein. We also found that the sera with higher cVLP antibody titers corresponded to patients with more sexual partners and pregnancies, and not always with to those with a high neutralizing activity. This novel assay could help in the development of a tool to evaluate cervical cancer risk.</p

    High performance fluoroelastomer composites filled withgraphite and/or bismuth oxide for applications ingamma-ray shielding

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    Fluoroelastomer-based composites with nano-sized bismuth oxide (B) and/orgraphite (G) as fillers were prepared and characterized using FKM type 1 fluoroe-lastomer as a matrix. The effects of these fillers used singly or in combination onthe crosslinking process, mechanical, thermal, dynamic mechanical, electrical,optical, and high-energy radiation attenuation properties of FKM were investi-gated. The results showed that graphite significantly increased the moduli E50(MPa) of FKM/G and FKM/GB composites by 1026% and 1459%, respectively,compared to FKM. On the other hand, bismuth(III) oxide did not affect the stiff-ness or elongation at break of FKM significantly. Graphite also imparted electricalconductivity to FKM (10 6Scm 1), which was reduced by bismuth oxide to10 12Scm 1. Furthermore, the linear attenuation coefficients (μ), half-value layer(HVL), and tenth-value layer (THV) ofpure FKM and FKM composites were eval-uated using a137Cs (662 keV) source, revealing that FKM/B and FKM/GB com-posites show 47.4% and 35.8% higherμvalues, respectively, than FKM. Takinginto consideration that the attenuation coefficient of FKM is 10 times higher thanconventional elastomers such as natural rubber, these results indicate that thinflexible shielding against high electromagnetic radiation can be achieved to pro-tect different sensitive equipment such as electronic devices used in nuclear powerplants, gamma radiation facilities, telescopes, and artificial satellites.Projects for Initiation in Research ANID-FONDECYT, Grant/Award Numbers:11200919, 11200437; ANID-FONDECYTRegular Project, Grant/Award Number:1221364 and 1191566; ANID—Millennium Science Initiative Program,Grant/Award Number: ICN2019_044;ANID BECAS/DOCTORADONACIONAL, Grant/Award Number:21211480Peer reviewe

    The Lockman-SpReSO project. Galactic flows in a sample of far-infrared galaxies

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    Methods. We performed measurements of the \MgII, \MgI, \FeIIa, \FeIIb, and \FeIIc\ spectral lines present in the spectra of the selected sample to determine the EW and velocity of the flows observed in the star-forming galaxies. Subsequently, we conducted 10710^7 bootstrap simulations using Spearman's rank correlation coefficient (ρs\rho_s) to explore correlations with galaxy properties. Furthermore, we calculated the covering factor, gas density, and optical depth for the measured \ion{Fe}{II} doublets. Results. Our analysis revealed strong correlations between the EW of \ion{Mg}{II} lines and both MM_{*} (ρs=0.43\rho_s=0.43, 4.5σ\sigma) and SFR (ρs=0.42\rho_s=0.42, 4.4σ\sigma). For the \ion{Fe}{II} lines, we observed strong correlations between the EW and SFR (ρs0.65\rho_s\sim0.65, >3.9σ>3.9\sigma), with a weaker correlation for MM_{*} (ρs0.35\rho_s\sim0.35, >1.9σ>1.9\sigma). No notable correlations were found between velocity measurements of \ion{Mg}{II} line and MM_{*}, SFR, or sSFR of the objects (ρs0.1)\rho_s\sim0.1). However, a negative strong correlation was found between the velocity of the \ion{Fe}{II} lines and the SFR of the galaxies (ρs0.45\rho_s\sim-0.45, 3σ\sim3\sigma). Our results align with previous studies but studying FIR-selected objects. Finally, we detected a candidate \textit{loitering outflow}, a recently discovered subtype of FeLoBAL quasar, at redshift of z=1.4399z=1.4399, exhibiting emission in \ion{C}{III}] and low line velocities (v|v|\lesssim 200 km/s).Comment: 25 pages, 31 figure
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