Type Ia Supernova Scenarios and the Hubble Sequence

The dependence of the Type Ia supernova (SN Ia) rate on galaxy type is examined for three currently proposed scenarios: merging of a Chandrasekhar--mass CO white dwarf (WD) with a CO WD companion, explosion of a sub--Chandrasekhar mass CO WD induced by accretion of material from a He star companion, and explosion of a sub--Chandrasekhar CO WD in a symbiotic system. The variation of the SNe Ia rate and explosion characteristics with time is derived, and its correlation with parent population age and galaxy redshift is discussed. Among current scenarios, CO + He star systems should be absent from E galaxies. Explosion of CO WDs in symbiotic systems could account for the SNe Ia rate in these galaxies. The same might be true for the CO + CO WD scenario, depending on the value of the common envelope parameter. A testable prediction of the sub--Chandrasekhar WD model is that the average brightness and kinetic energy of the SN Ia events should increase with redshift for a given Hubble type. Also for this scenario, going along the Hubble sequence from E to Sc galaxies SNe Ia events should be brighter on average and should show larger mean velocities of the ejecta. The observational correlations strongly suggest that the characteristics of the SNe Ia explosion are linked to parent population age. The scenario in which WDs with masses below the Chandrasekhar mass explode appears the most promising one to explain the observed variation of the SN Ia rate with galaxy type together with the luminosity--expansion velocity trend.Comment: 16 pages uuencoded compressed Postscript, 2 figures included. ApJ Letters, in pres

Clinicopathologic study on the effects of Glyphosate (Roundup?) at sublethal levels in a murine experimental model

P?ginas 17-24Recurso Electr?nicoEn Colombia, los pesticidas a base de glifosato se usan para el control de malezas en la agricultura y erradicaci?n de cultivos il?citos. Sin embargo, los efectos t?xicos en animales y humanos expuestos a dosis subletales son desconocidos. Este estudio evalu? los efectos cl?nico-patol?gicos de dietas con 7,5 ppm y 15 ppm glifosato en ratones Mus musculus gestantes, usando el herbicida Roundup?. Se registr? el peso corporal de las hembras, de sus cr?as, y la viabilidad de las camadas diariamente. Las lesiones macrosc?picas e histopatol?gicas en el h?gado, ri??n, ?tero y cerebro se determinaron a trav?s de necropsias en los d?as 5, 30 y 45 despu?s de la exposici?n, adem?s de los ?ndices org?nicos hep?tico y cardiaco. No hubo diferencias significativas en el peso corporal, el tama?o y la viabilidad de las camadas a ninguna de las dosis evaluadas. Se observ? congesti?n y aumento en el tama?o del h?gado, ri??n y bazo, despu?s de 5 d?as de exposici?n, sugiriendo un proceso de desintoxicaci?n. A 30 y 45 d?as, no se observaron signos cl?nicos ni lesiones patol?gicas atribuibles al glifosato; sin embargo, un aumento en el tama?o de los hepatocitos, con contenido vacuolar y granular de aspecto protein?ceo indican un efecto evidente, aunque sutil del Roundup? a dosis subletales con posible adaptabilidad org?nica. Se concluye que el consumo de alimento con 7,5 ppm y 15 ppm de glifosato durante 5, 30 y 45 d?as causa alteraciones sutiles de toxicidad en ratones durante la gestaci?n, la lactancia y el posparto, pero no en sus camadas.ABSTRACT. In Colombia, glyphosate-based pesticides are used for weed control in agriculture and eradication of illicit crops; however, the toxic effects in animals and humans exposed to sublethal doses are unknown. This study evaluated the clinical and pathological changes induced by diets containing glyphosate at 7,5 ppm and 15 ppm in pregnant mice Mus musculus, using the herbicide Roundup ?. The body-weight of pregnant females and offspring and the viability of litters were recorded daily. Gross and microscopic lesions in liver, kidney, uterus and brain were determined at necropsies performed at 5, 30 and 45 days post- exposure, in addition to the liver and heart organic indexes. No significant differences were found in body weight, size and viability of litters at any dose. Organs such as the liver, kidney and spleen were enlarged and congested at day 5 post exposure, suggesting a detoxification process. At 30 and 45 days, no clinical signs or pathological lesions attributed to glyphosate were found. However, there was an increase in the hepatocyte size, with vacuolar and granular cytoplasm and proteinaceus-like content, suggesting a subtle effect of sublethal doses of Roundup ?, with possible organ adaptability. We conclude that the consumption of food containing 7.5 ppm and 15 ppm of glyphosate for 5, 30 and 45 days, cause subtle toxic alterations in mice during pregnancy, lactation and postpartum, but not in their litters

Depolarization-repolarization synchrony after right ventricular and left bundle branch area pacing

Introduction: Left bundle branch area pacing (LBBAP) has been recently proposed to overcome the limitations associated with right ventricular pacing (RVP) and has been suggested as a new physiological pacing form with high feasibility and safety. A greater difference between QRS complex and T-wave angle directions has been proposed as a marker of abnormal electrical activity in several patient populations, but a comparison between these two pacing modalities has never been performed. The total cosine R to T (TCRT) is an ECG descriptor that accounts for depolarization-repolarization synchrony by measuring the difference between their directions. The purpose of this study was to compare TCRT in patients referred for RVP and LBBAP pacing as anti-bradycardia therapy. Methods: ECG recordings from 134 patients (82 LBBAP, 52 RVP) were classified into two groups, narrow QRS and wide QRS, depending on the patient’s QRS duration prior to implantation. In the post-implantation state, the TCRT index was calculated from a median beat calculated for each patient. Singular value decomposition was applied to the median beat in the eight independent ECG leads (I, II, V1, V2, V3, V4, V5, V6). The QRS complex and T wave loops in a three-dimensional space were determined from the first three components of the decomposition. TCRT was computed as the average of the cosines of the angles between the QRS complex directions and the maximum T wave direction. More positive values corresponded to more synchronized depolarization and repolarization processes while more negative values indicated larger differences in the orientation of the QRS and T wave loops and, therefore, greater dyssynchronization. Results: showed that TCRT took negative values for both techniques, RVP and LBBAP, and both groups, narrow and wide QRS, indicating that pacing generated dyssynchronization between ventricular depolarization and repolarization. Nevertheless, TCRT values for both groups were significantly more negative (p<0.01) for RVP than for LBBAP. We hypothesize that cardiac memory induced by pacing could account for these negative TCRT values. In any case, LBBAP did not increase the difference in the QRS complex and T wave loop orientations as much as RVP. Conclusion: LBBAP induces less dyssynchrony than RVP in the depolarization-repolarization process

The Age-Redshift Relation for Standard Cosmology

We present compact, analytic expressions for the age-redshift relation $\tau(z)$ for standard Friedmann-Lema\^ \itre-Robertson-Walker (FLRW) cosmology. The new expressions are given in terms of incomplete Legendre elliptic integrals and evaluate much faster than by direct numerical integration.Comment: 13 pages, 3 figure

The evolution of H{\sc ii} galaxies: Testing the bursting scenario through the use of self-consistent models

We have computed a series of realistic and self-consistent models of the emitted spectra of H{\sc ii} galaxies. Our models combine different codes of chemical evolution, evolutionary population synthesis and photoionization. The emitted spectrum of H{\sc ii} galaxies is reproduced by means of the photoionization code CLOUDY, using as ionizing spectrum the spectral energy distribution of the modelled H{\sc ii} galaxy, which in turn is calculated according to a Star Formation History (SFH) and a metallicity evolution given by a chemical evolution model that follows the abundances of 15 different elements. The contribution of emission lines to the broad-band colours is explicitly taken into account. The results of our code are compared with photometric and spectroscopic data of H{\sc ii} galaxies. Our technique reproduces observed diagnostic diagrams, abundances, equivalent width-colour and equivalent width-metallicity relations for local H{\sc ii} galaxies.Comment: 13 figures and 2 tables, accepted for publication in MNRAS Main Journa

One hundred sherds of grey: compositional and technological characterization of Medieval greyware pottery production at Cabrera d'Anoia, Catalonia, Spain

Detailed petrographic and geochemical analyses of 100 sherds of greyware cooking pottery from the large Medieval kiln site of Cabrera d’Anoia have revealed the presence of several compositional groups that are correlated to different phases in the operation of the site. These appear to relate to changes in the extraction of local raw materials for pottery production concomitant with the development of the workshop over several centuries. Macroscopic, microstructural and mineralogical analyses have permitted the reconstruction of a consistent tradition of ceramic manufacture at d’Anoia. Close correspondence between the petrographic and geochemical characterisation of the sherds provides several well-defined compositional reference groups for this major production centre. This is permitting the identification of the products of Cabrera d’Anoia at other rural sites in Catalonia and will provide a firm basis with which to examine the supply and demand of utilitarian pottery vessels in this area during the Medieval period

Differentiating dark energy and modified gravity with galaxy redshift surveys

The observed cosmic acceleration today could be due to an unknown energy component (dark energy), or a modification to general relativity (modified gravity). If dark energy models and modified gravity models are required to predict the same cosmic expansion history H(z), they will predict different growth rate for cosmic large scale structure, f_g(z)=d\ln \delta/d\ln a (\delta=(\rho_m-\bar{\rho_m})/\bar{\rho_m}), a is the cosmic scale factor). If gravity is not modified, the measured H(z) leads to a unique prediction for f_g(z), f_g^H(z). Comparing f_g^H(z) with the measured f_g(z) provides a transparent and straightforward test of gravity. We show that a simple \chi^2 test provides a general figure-of-merit for our ability to distinguish between dark energy and modified gravity given the measured H(z) and f_g(z). We study a magnitude-limited NIR galaxy redshift survey covering >10,000 (deg)^2 and the redshift range of 0.5<z<2. The resultant data can be divided into 7 redshift bins, and yield the measurement of H(z) to the accuracy of 1-2% via baryon acoustic oscillation measurements, and f_g(z) to the accuracy of a few percent via the measurement of redshift space distortions and the bias factor which describes how light traces mass. We find that if the H(z) data are fit by both a DGP gravity model and an equivalent dark energy model that predict the same expansion history, a survey area of 11,931 (deg)^2 is required to rule out the DGP gravity model at the 99.99% confidence level. It is feasible for such a galaxy redshift survey to be carried out by the next generation space missions from NASA and ESA, and it will revolutionize our understanding of the universe by differentiating between dark energy and modified gravity.Comment: 6 pages, 2 color figures. Expanded version accepted by JCA

Validation of a new In Vitro Sun Protection Factor (SPF) method to include a wide range of sunscreen product emulsion types

In 2017, Cosmetics Europe performed a double-blinded ring test of 24 emulsion-type sunscreen products, across 3 in vivo test laboratories and 3 in vitro test laboratories, using a new candidate in vitro SPF test method. Based on the results of this work, an article was published showing how data derived from a new lead candidate method conform to new International Standards (ISO) acceptance criteria for alternative SPF test methods (Any alternative method should consider the matrix effect and if required, specify the matrix applicability of the method; Criterion 1a: Systematic differences between methods should be negligible: 95% of all individual results of an alternative method are within the range of ±2× reproducibility standard deviation of the in vivo method, that is overall bias must be below 0.5× reproducibility standard deviation of the in vivo method; Criterion 1b: Measurement uncertainty of an alternative method should be below the measurement uncertainty of the in vivo method. Candidate method predicted values must fall within the full 'funnel' (SPF 6-50+) limits proposed by Cosmetics Europe (derived from the same minimum test design, that is using the ISO24444 Method to measure at least 24 products across at least 3 laboratories using at least 5 test subjects/laboratory, in a blinded fashion).). Of the 24 sunscreen products tested, the majority of emulsions were of the oil-in-water (O/W) type, whereas only one was water-in-oil (W/O) and there were no products with a mineral-only sun filter system. In order to confirm the scope of this method, therefore, a new study was conducted that included 73 W/O (12 mineral + organic, 44 mineral only and 17 organic only) and 3 O/W mineral-only, emulsion-type sunscreen products (a total of 76 new sunscreen products). When combined with the previous 24 products (tested in 3 different laboratories), this yielded a new data set comprising a total of 100 emulsion-type sunscreen products, with SPF values ranging from 6 to 50+ (with a total of 148 data points). These products were tested using the double-plate in vitro SPF test method and compared with the ISO TC217/WG7 acceptance criteria for alternative SPF test methods. Over 95% of paired in vitro: in vivo SPF values lay within the upper and lower limits of the ISO acceptance criteria funnel, with no bias. This new in vitro SPF test method, therefore, meets the minimum requirements for an alternative SPF test method to ISO24444:2010, for emulsion-type sunscreen products (which make up the majority of marketed sunscreen products)