7,598 research outputs found

    Effect of mould inoculation on formation of chunky graphite in heavy section spheroidal graphite cast iron parts

    Get PDF
    The manufacturing process of heavy section ductile iron castings is strongly influenced by the risk of graphite degeneration under slow cooling rates. Appearance of this kind of defect is commonly linked to significant reductions in the mechanical properties of large castings. Studies on the effect of inoculation on chunky graphite formation in heavy sections have led to contradictory results in the literature and this triggered the present work. New experimental data are presented on the effect of mould inoculation on chunky graphite appearance during solidification of nodular irons which clearly demonstrate that mould inoculation increases the risk of chunky graphite formation in heavy sections. This is in agreement with some previous works which are reviewed, and it is suggested that the contradiction with other results could relate to the fact that these latter works dealt with chill casting

    A search for water maser emission toward obscured post-AGB star and planetary nebula candidates

    Full text link
    Water maser emission at 22 GHz is a useful probe to study the transition between the nearly spherical mass-loss in the AGB to a collimated one in the post-AGB phase. In their turn, collimated jets in the post-AGB phase could determine the shape of planetary nebulae (PNe) once photoionization starts. We intend to find new cases of post-AGB stars and PNe with water maser emission, including water fountains or water-maser-emitting PNe. We observed water maser emission in a sample of 133 objects, with a significant fraction being post-AGB and young PN candidate sources with strong obscuration. We detected this emission in 15 of them, of which seven are reported here for the first time. We identified three water fountain candidates: IRAS 17291-2147, with a total velocity spread of ~96 km/s in its water maser components and two sources (IRAS 17021-3109 and IRAS 17348-2906) that show water maser emission outside the velocity range covered by OH masers. We have also identified IRAS 17393-2727 as a possible new water-maser-emitting PN. The detection rate is higher in obscured objects (14%) than in those with optical counterparts (7%), consistent with previous results. Water maser emission seems to be common in objects that are bipolar in the near-IR (43% detection rate). The water maser spectra of water fountain candidates like IRAS 17291-2147 show significantly less maser components than others (e.g., IRAS 18113-2503). We speculate that most post-AGBs may show water maser emission with wide enough velocity spread (> 100 km/s) when observed with enough sensitivity and/or for long enough periods of time. Therefore, it may be necessary to single out a special group of "water fountains", probably defined by their high maser luminosities. We also suggest that the presence of both water and OH masers in a PN is a better tracer of its youth, rather than the presence of just one of these species.Comment: To be published in Astronomy & Astrophysics. 16 pages, 1 figure (spanning 5 pages). This version includes some minor language corrections and fixes some errors in Table

    Point Source Detection with Fully-Convolutional Networks: Performance in Realistic Simulations

    Full text link
    Point sources (PS) are one of the main contaminants to the recovery of the cosmic microwave background (CMB) signal at small scales, and their detection is important for the next generation of CMB experiments. We develop a method (PoSeIDoN) based on fully convolutional networks to detect PS in realistic simulations, and we compare its performance against one of the most used PS detection method, the Mexican hat wavelet 2 (MHW2). We produce realistic simulations of PS taking into account contaminating signals as the CMB, the cosmic infrared background, the Galactic thermal emission, the thermal Sunyaev-Zel'dovich effect, and the instrumental and PS shot noises. We first produce a set of training simulations at 217 GHz to train the network. Then we apply both PoSeIDoN and the MHW2 to recover the PS in the validating simulations at all 143, 217, and 353 GHz, comparing the results by estimating the reliability, completeness, and flux density accuracy and by computing the receiver operating characteristic curves. In the extra-galactic region with a 30{\deg} galactic cut, the network successfully recovers PS at 90% completeness corresponding to 253, 126, and 250 mJy for 143, 217, and 353 GHz respectively. The MHW2 with a 3σ\sigma flux density detection limit recovers PS up to 181, 102, and 153 mJy at 90% completeness. In all cases PoSeIDoN produces a much lower number of spurious sources with respect to MHW2. The results on spurious sources for both techniques worsen when reducing the galactic cut to 10{\deg}. Our results suggest that using neural networks is a very promising approach for detecting PS, providing overall better results in dealing with spurious sources with respect to usual filtering approaches. Moreover, PoSeIDoN gives competitive results even at nearby frequencies where the network was not trained.Comment: 12 pages, 6 figures, accepted Astronomy & Astrophysic

    Creencias sexistas y actitudes de violencia de género. Situación de estudiantes universitario del área de la salud. Cartagena - Colombia

    Get PDF
    Introduction: Violence towards women is a problem that attempts towards equalness, the development of social peace. Situation that is acknowledged as a factor associated with the deterioration in the quality of life of the individuals as it is constituted a violation of human rights. Target: To describe the degree of agreement and disagreement between the sexist beliefs and those that lead students in the health area of superior education institution of Cartagena. Materials and methods: Descriptive study, cross-sectional the calculated sample was of 509 students, selected through convenience sampling, the questionnaire of attitudes towards gender and violence was used. (C.A.G.V), the questionnaire was divided in two sections, the first one, deals with social demographics the second, sexist beliefs and violance.Results: The factor with the most disagreement and rejected to sexist beliefs it is factor 1 with 79% of participants in disagreement, the factors 2,3,4 a high percentage is shown of disagreement and indifference in men and women to the evaluated beliefs. Conclusion: It is concluded that exists behaviors that promote violence, and this study was evidenced domination, isolation and conducts that pass unnotified, this is how violence against women done by the partner or ex-partner opens fields to important health issues; problems that have shown an unbalanced and well-being psychosocial in long and short term.Introducción: La violencia contra la mujer es un problema que atenta contra la igualdad, el desarrollo y la paz social. Situación que se reconoce como factor asociado al deterioro en la calidad de vida de los individuos en la medida que se constituye en violación de los Derechos Humanos. Objetivo: Describir el grado de acuerdo o desacuerdo entre las creencias sexistas y las que conducen a la violencia en estudiantes del área de la salud de una Institución de Educación Superior de Cartagena. Materiales y métodos: Estudio descriptivo, transversal, la muestra calculada fue de 509 estudiantes, seleccionados mediante muestreo por conveniencia, se utilizó el cuestionario de Actitudes hacia el Género y la Violencia (C.A.G.V), el cuestionario se dividió en dos secciones, la primera, aborda datos sociodemográficos, la segunda, las creencias sexistas y violencia. Resultados: El factor con mayor desacuerdo y/o rechazo a las creencias sexistas es el factor 1 con un 79% de participantes en desacuerdo, los factores 2, 3 y 4 tiene presentan un alto porcentaje de desacuerdo y actitud indiferente en hombres y mujeres ante las creencias evaluadas. Conclusión: Se concluye que existen comportamientos que promueven la violencia, en este estudio se evidenció dominación, aislamiento y conductas que suelen pasar inadvertidas, es así como la violencia contra las mujeres ejercidas por sus parejas o ex parejas abre campos a importantes problemas de salud, problemas que han demostrado un desequilibrio del bienestar psicosocial a corto y/o a largo plazo

    Association of Systemic Lupus Erythematosus Clinical Features with European Population Genetic Substructure

    Get PDF
    Systemic Lupus Erythematosus (SLE) is an autoimmune disease with a very varied spectrum of clinical manifestations that could be partly determined by genetic factors. We aimed to determine the relationship between prevalence of 11 clinical features and age of disease onset with European population genetic substructure. Data from 1413 patients of European ancestry recruited in nine countries was tested for association with genotypes of top ancestry informative markers. This analysis was done with logistic regression between phenotypes and genotypes or principal components extracted from them. We used a genetic additive model and adjusted for gender and disease duration. Three clinical features showed association with ancestry informative markers: autoantibody production defined as immunologic disorder (P = 6.8×10(-4)), oral ulcers (P = 6.9×10(-4)) and photosensitivity (P = 0.002). Immunologic disorder was associated with genotypes more common in Southern European ancestries, whereas the opposite trend was observed for photosensitivity. Oral ulcers were specifically more common in patients of Spanish and Portuguese self-reported ancestry. These results should be taken into account in future research and suggest new hypotheses and possible underlying mechanisms to be investigated. A first hypothesis linking photosensitivity with variation in skin pigmentation is suggested

    On the mechanism of the digold(I) hydroxide-catalyzed hydrophenoxylation of alkynes

    Get PDF
    Herein we present a detailed investigation of the mechanistic aspects of the dual gold-catalysed hydrophenoxylation of alkynes, using both experimental and computational methods. The dissociation of [{Au(NHC)}2(µ-OH)][BF4] is essential to enter the catalytic cycle; this step is favored in the presence of bulky, non-coordinating counterions. Moreover, in silico studies confirmed that phenol does not only act as a reactant, but as a co-catalyst, lowering the energy barriers for several transition states. A gem-diaurated species might form during the reaction, but this lies deep within a potential energy well, and is likely to be an ‘off-cycle’ rather than an ‘in-cycle’ intermediate

    Epigenetic inactivation of the splicing RNA-binding protein CELF2 in human breast cancer

    Get PDF
    Altres ajuts: This work was co-finaced by the European Development Regional Fund, "A way to achieve Europe" ERDF; the Cellex Foundation; and "la Caixa" Banking Foundation (LCF/PR/PR15/ 11100003).Human tumors show altered patterns of protein isoforms that can be related to the dysregulation of messenger RNA alternative splicing also observed in transformed cells. Although somatic mutations in core spliceosome components and their associated factors have been described in some cases, almost nothing is known about the contribution of distorted epigenetic patterns to aberrant splicing. Herein, we show that the splicing RNA-binding protein CELF2 is targeted by promoter hypermethylation-associated transcriptional silencing in human cancer. Focusing on the context of breast cancer, we also demonstrate that CELF2 restoration has growth-inhibitory effects and that its epigenetic loss induces an aberrant downstream pattern of alternative splicing, affecting key genes in breast cancer biology such as the autophagy factor ULK1 and the apoptotic protein CARD10. Furthermore, the presence of CELF2 hypermethylation in the clinical setting is associated with shorter overall survival of the breast cancer patients carrying this epigenetic lesion

    Dispersion, solvent and metal effects in the binding of gold cations to alkynyl ligands: implications for Au(i) catalysis.

    Get PDF
    The coordination modes of the [Au(PPh3)](+) cation to metal alkynyl complexes have been investigated. On addition to ruthenium, a vinylidene complex, [Ru(η(5)-C5H5)(PPh3)2([double bond, length as m-dash]C[double bond, length as m-dash]CPh{AuPPh3})](+), is obtained while addition to a gold(iii) compound gives di- and trinuclear gold complexes depending on the conditions employed. In the trinuclear species, a gold(i) cation is sandwiched between two gold(iii) alkynyl complexes, suggesting that coordination of multiple C-C triple bonds to gold is facile
    • …
    corecore