906 research outputs found

    Determination of pulsation periods and other parameters of 2875 stars classified as MIRA in the All Sky Automated Survey (ASAS)

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    We have developed an interactive PYTHON code and derived crucial ephemeris data of 99.4% of all stars classified as 'Mira' in the ASAS data base, referring to pulsation periods, mean maximum magnitudes and, whenever possible, the amplitudes among others. We present a statistical comparison between our results and those given by the AAVSO International Variable Star Index (VSX), as well as those determined with the machine learning automatic procedure of Richards et al. 2012. Our periods are in good agreement with those of the VSX in more than 95% of the stars. However, when comparing our periods with those of Richards et al, the coincidence rate is only 76% and most of the remaining cases refer to aliases. We conclude that automatic codes require still more refinements in order to provide reliable period values. Period distributions of the target stars show three local maxima around 215, 275 and 330 d, apparently of universal validity, their relative strength seems to depend on galactic longitude. Our visual amplitude distribution turns out to be bimodal, however 1/3 of the targets have rather small amplitudes (A << 2.5m^{m}) and could refer to semi-regular variables (SR). We estimate that about 20% of our targets belong to the SR class. We also provide a list of 63 candidates for period variations and a sample of 35 multiperiodic stars which seem to confirm the universal validity of typical sequences in the double period and in the Petersen diagramsComment: 14 pages, 14 figures, and 8 tables. Accepted to The Astrophysical Journal Supplement Series, September 201

    IMAGES I. Strong evolution of galaxy kinematics since z=1

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    (abbreviated) We present the first results of the ESO large program, ``IMAGES'' which aims at obtaining robust measurements of the kinematics of distant galaxies using the multi-IFU mode of GIRAFFE on the VLT. 3D spectroscopy is essential to robustly measure the often distorted kinematics of distant galaxies (e.g., Flores et al. 2006). We derive the velocity fields and σ\sigma-maps of 36 galaxies at 0.4<z<0.75 from the kinematics of the [OII] emission line doublet, and generate a robust technique to identify the nature of the velocity fields based on the pixels of the highest signal-to-noise ratios (S/N). We have gathered a unique sample of 63 velocity fields of emission line galaxies (W0([OII]) > 15 A) at z=0.4-0.75, which are a representative subsample of the population of M_stellar>1.5x10^{10} M_sun emission line galaxies in this redshift range, and are largely unaffected by cosmic variance. Taking into account all galaxies -with or without emission lines- in that redshift range, we find that at least 41+/-7% of them have anomalous kinematics, i.e., they are not dynamically relaxed. This includes 26+/-7% of distant galaxies with complex kinematics, i.e., they are not simply pressure or rotationally supported. Our result implies that galaxy kinematics are among the most rapidly evolving properties, because locally, only a few percent of the galaxies in this mass range have complex kinematics.Comment: 17 pages, 6 figures, Accepted by A&

    IMAGES II. A surprisingly low fraction of undisturbed rotating spiral disks at z~0.6: The morpho-kinematical relation 6 Gyrs ago

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    We present a first combined analysis of the morphological and dynamical properties for the Intermediate MAss Galaxy Evolution Sequence (IMAGES) sample. It is a representative sample of 52 z~0.6 galaxies with Mstell from 1.5 to 15 10^10Msun and possessing 3D resolved kinematics and HST deep imaging in at least two broad band filters. We aim at evaluate robustly the evolution of rotating spirals since z~0.6, as well as to test the different schemes for classifying galaxies morphologically. We used all the information provided by multi-band images, color maps and 2 dimensional light fitting to assign to each object a morphological class. We divided our sample between spiral disks, peculiar objects, compact objects and mergers. Using our morphological classification scheme, 4/5 of identified spirals are rotating disks and more than 4/5 of identified peculiar galaxies show complex kinematics, while automatic classification methods such as Concentration-Asymmetry and GINI-M20 severely overestimate the fraction of relaxed disk galaxies. Using this methodology, we find that the fraction of rotating spirals has increased by a factor ~ 2 during the last 6 Gyrs, a much higher fraction that found previously based on morphologies alone. These rotating spiral disks are forming stars very rapidly, doubling their stellar masses over the last 6 Gyrs, while most of their stars have been formed few Gyrs earlier, which reveals the presence of a large gas supply. Because they are likely the progenitors of local spirals, we can conjecture how their properties are evolving. Their disks show some evidence for an inside-out growth and the gas supply/accretion is not made randomly as the disk need to be stable in order to match the local disk properties.Comment: Typos corrected, reference adde

    Hot topics, urgent priorities, and ensuring success for racial/ethnic minority young investigators in academic pediatrics.

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    BackgroundThe number of racial/ethnic minority children will exceed the number of white children in the USA by 2018. Although 38% of Americans are minorities, only 12% of pediatricians, 5% of medical-school faculty, and 3% of medical-school professors are minorities. Furthermore, only 5% of all R01 applications for National Institutes of Health grants are from African-American, Latino, and American Indian investigators. Prompted by the persistent lack of diversity in the pediatric and biomedical research workforces, the Academic Pediatric Association Research in Academic Pediatrics Initiative on Diversity (RAPID) was initiated in 2012. RAPID targets applicants who are members of an underrepresented minority group (URM), disabled, or from a socially, culturally, economically, or educationally disadvantaged background. The program, which consists of both a research project and career and leadership development activities, includes an annual career-development and leadership conference which is open to any resident, fellow, or junior faculty member from an URM, disabled, or disadvantaged background who is interested in a career in academic general pediatrics.MethodsAs part of the annual RAPID conference, a Hot Topic Session is held in which the young investigators spend several hours developing a list of hot topics on the most useful faculty and career-development issues. These hot topics are then posed in the form of six "burning questions" to the RAPID National Advisory Committee (comprised of accomplished, nationally recognized senior investigators who are seasoned mentors), the RAPID Director and Co-Director, and the keynote speaker.Results/conclusionsThe six compelling questions posed by the 10 young investigators-along with the responses of the senior conference leadership-provide a unique resource and "survival guide" for ensuring the academic success and optimal career development of young investigators in academic pediatrics from diverse backgrounds. A rich conversation ensued on the topics addressed, consisting of negotiating for protected research time, career trajectories as academic institutions move away from an emphasis on tenure-track positions, how "non-academic" products fit into career development, racism and discrimination in academic medicine and how to address them, coping with isolation as a minority faculty member, and how best to mentor the next generation of academic physicians

    Images IV: Strong evolution of the oxygen abundance in gaseous phases of intermediate mass galaxies since z=0.8

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    Intermediate mass galaxies (logM(Msun)>10) at z~0.6 are the likeliest progenitors of the present-day numerous population of spirals. There is growing evidence that they have evolved rapidly since the last 6 to 8 Gyr ago, and likely have formed a significant fraction of their stellar mass, often showing perturbed morphologies and kinematics. We have gathered a representative sample of 88 such galaxies and have provided robust estimates of their gas phase metallicity. For doing so, we have used moderate spectral resolution spectroscopy at VLT/FORS2 with unprecedented high S/N allowing to remove biases coming from interstellar absorption lines and extinction to establish robust values of R23=([OII]3727 + [OIII]4959,5007)/Hbeta. We definitively confirm that the predominant population of z~0.6 starbursts and luminous IR galaxies (LIRGs) are on average, two times less metal rich than the local galaxies at a given stellar mass. We do find that the metal abundance of the gaseous phase of galaxies is evolving linearly with time, from z=1 to z=0 and after comparing with other studies, from z=3 to z=0. Combining our results with the reported evolution of the Tully Fisher relation, we do find that such an evolution requires that ~30% of the stellar mass of local galaxies have been formed through an external supply of gas, thus excluding the close box model. Distant starbursts & LIRGs have properties (metal abundance, star formation efficiency & morphologies) similar to those of local LIRGs. Their underlying physics is likely dominated by gas infall probably through merging or interactions. Our study further supports the rapid evolution of z~0.4-1 galaxies. Gas exchanges between galaxies is likely the main cause of this evolution.Comment: 21 pages, 12 figures, A&A, In pres

    Metales pesados en polvo atmosférico depositado en hojas de Acacia farnesiana (Fabaceae) y Prosopis laevigata (Fabaceae)

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    Atmospheric dust establishes an element of study to know the distribution of pollutant particles such as heavy metals and their effects on ecological systems. The objective was to determine the elemental composition of particles deposited in two species of trees as an indicator of environmental impact in San Luis Potosí, México. The distribution of Acacia farnesiana and Prosopis laevigata trees was taken into account in five soil uses to collect leaf material and extract atmospheric dust during the spring and summer seasons, determining the concentration of heavy metals using the ICP-MS technique. The results indicated the presence of Al&gt; Cu&gt; Zn&gt; Pb&gt; V&gt; As&gt; Ni&gt; Cd&gt; Ti&gt; Cr&gt; Co. Correlations with values of r2&gt; 0.90 were presented between V-Ti, Ni-V, Ni-Ti, Al-Ti and Cr-V. The species factor conditioned the concentrations of Al, Ti, V, Cr, Ni and Zn mainly in the particles deposited in Prosopis leaves. Particles of nine elements were conditioned by the activities of the five land uses, where the use of mineral soil affected by the presence of Al, Cd, Co, Pb, Cu and Zn. Concentrations of Cd were 6.2 times higher in the use of mining soil than in the agricultural sector; 5.9 and 5.4 times the concentrations of Co and Pb in the use of mining soil with respect to the trade and service respectively. The season had only significant effects on Cr and Pb particles. This study indicates the existence of pollutants that can affect ecological systems so it falls within the context of continued evaluation of environmental impacts.El polvo atmosférico se establece como elemento de estudio para conocer la distribución de partículas contaminantes, como son los metales pesados y sus efectos sobre los sistemas ecológicos. El objetivo fue determinar la composición elemental de las partículas depositadas en dos especies de árboles como un indicador de impacto ambiental en San Luis Potosí, México. La distribución de los árboles de Acacia farnesiana y Prosopis laevigata se tomó en cuenta en cinco usos del suelo para recolectar material foliar y extraer el polvo atmosférico durante la primavera y el verano, determinando la concentración de metales pesados utilizando la técnica ICP-MS. Los resultados indicaron la presencia de Al&gt; Cu&gt; Zn&gt; Pb&gt; V&gt; As&gt; Ni&gt; Cd&gt; Ti&gt; Cr&gt; Co. Se presentaron correlaciones con valores de r2&gt; 0,90 entre V-Ti, Ni-V, Ni-Ti, Al-Ti y Cr-V. El factor especie condicionó las concentraciones de Al, Ti, V, Cr, Ni y Zn principalmente en las partículas depositadas en las hojas de Prosopis. Las partículas de nueve elementos fueron condicionadas por las actividades de los cinco usos de la tierra, donde el uso del suelo mineral se vio afectado por la presencia de Al, Cd, Co, Pb, Cu y Zn. Las concentraciones de Cd fueron 6,2 veces más altas en el uso de suelo minero que en el sector agrícola; 5,9 y 5,4 veces las concentraciones de Co y Pb en el uso del suelo minero con respecto al comercio y al servicio, respectivamente. La temporada solo tuvo efectos significativos sobre las partículas de Cr y Pb. Este estudio indica la existencia de contaminantes que pueden afectar los sistemas ecológicos, por lo que entran en el contexto de la evaluación de los impactos ambientales.Fil: Jorge Alcalá Jáuregui. Universidad Autónoma de San Luis Potosí. Facultad de AgronomíaFil: Juan C. Rodríguez Ortiz. Universidad Autónoma de San Luis Potosí. Facultad de AgronomíaFil: Alejandra Hernández Montoya. Universidad Autónoma de San Luis Potosí. Facultad de AgronomíaFil: María Flavia Filippini. Universidad Nacional de Cuyo. Facultad de Ciencias AgrariasFil: Eduardo Martinez Carretero. Instituto Argentino de Investigaciones de las Zonas Áridas Fil: Paola Elizabeth Díaz Flores. Universidad Autónoma de San Luis Potosí. Facultad de AgronomíaFil: Ángel Natanael Rojas Velázquez. Universidad Autónoma de San Luis Potosí. Facultad de AgronomíaFil: Humberto Rodríguez-Fuentes. Universidad Autónoma de Nuevo León (México). Facultad de Agronomía.Fil: Félix Alfredo Beltrán Morales. Universidad Autónoma de Baja California Sur (México

    IMAGES-III: The evolution of the Near-Infrared Tully-Fisher relation over the last 6 Gyr

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    Using the multi-integral field spectrograph GIRAFFE at VLT, we have derived the K-band Tully-Fisher relation (TFR) at z~0.6 for a representative sample of 65 galaxies with emission lines. We confirm that the scatter in the z~0.6 TFR is caused by galaxies with anomalous kinematics, and find a positive and strong correlation between the complexity of the kinematics and the scatter that they contribute to the TFR. Considering only relaxed-rotating disks, the scatter, and possibly also the slope of the TFR, do not appear to evolve with z. We detect an evolution of the K-band TFR zero point between z~0.6 and z=0, which, if interpreted as an evolution of the K-band luminosity of rotating disks, would imply that a brightening of 0.66+/-0.14 mag occurs between z~0.6 and z=0. Any disagreement with the results of Flores et al. (2006) are attributed to both an improvement of the local TFR and the more detailed accurate measurement of the rotation velocities in the distant sample. Most of the uncertainty can be explained by the relatively coarse spatial-resolution of the kinematical data. Because most rotating disks at z~0.6 are unlikely to experience further merging events, one may assume that their rotational velocity does not evolve dramatically. If true, our result implies that rotating disks observed at z~0.6 are rapidly transforming their gas into stars, to be able to double their stellar masses and be observed on the TFR at z=0. The rotating disks observed are indeed emission-line galaxies that are either starbursts or LIRGs, which implies that they are forming stars at a high rate. Thus, a significant fraction of the rotating disks are forming the bulk of their stars within 6 to 8 Gyr, in good agreement with former studies of the evolution of the M-Z relation.Comment: 17 pages, 11 figures, accepted for publication in A&A. v2 taking into account comments from language edito

    Pattern recognition applying LDA and LR to optoelectronic signals of optical scanning systems

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    [ES] Este artículo da seguimiento a previas experimentaciones actualmente publicadas acerca de la minimización de ruido ópticoeléctrico en los sistemas de barrido óptico OSS (en inglés, Optical Scanning Systems), implementando técnicas computacionales para el reconocimiento de los patrones que se generan de cada fuente de referencia y que son utilizadas para indicar una coordenada que el OSS monitoreará. Técnicas como análisis linear discriminante LDA (en inglés, Linear Discriminant Analysis) y regresión lineal LR (en inglés, Linear Regression) fueron implementadas para discriminar las señales causadas por otras fuentes distintas a las de referencia. Para aumentar la eficiencia de estos modelos fueron implementados codificación predictiva lineal LPC (en inglés, Linear Predictive Coding) y Cuantiles como extractores de características. Los resultados fueron alentadores con tasas de reconocimiento mayores al 91.2 %, alcanzando en algunos casos una exactitud del 100 %.[EN] This paper is a follow-up to previous researches already published regarding the minimization of optical-electrical noise in optical scanning systems OSS, by the implementation of computational techniques for pattern recognition generated by each reference source used to indicate a coordinate that the OSS will be monitoring. Techniques such as linear discriminant analysis LDA and linear regression LR were implemented in order to discriminate the signals caused by other sources different to the references. In order to enhance the efficiency of these models was implemented linear predictive coding LPC and quantiles as features extractors. The results were encouraging with rates of recognition greater than 91.2 %, reaching in some cases an accuracy of 100 %.Miranda-Vega, JE.; Rivas-López, M.; Flores-Fuentes, W.; Sergiyenko, O.; Lindner, L.; Rodríguez-Quiñonez, JC. (2020). Reconocimiento de patrones aplicando LDA y LR a señales optoelectrónicas de sistemas de barrido óptico. Revista Iberoamericana de Automática e Informática industrial. 17(4):401-411. https://doi.org/10.4995/riai.2020.12385OJS401411174Brooks, D. R., Mims III, F. M., 2001. Development of an inexpensive handheld led-based sun photometer for the globe program. Journal of Geophysical Research: Atmospheres 106 (D5), 4733-4740. https://doi.org/10.1029/2000JD900545Cervantes, J., Taltempa, J., Lamont, F. G., Castilla, J. S. R., Rendon, A. Y., Jali- li, L. D., 2017. Análisis comparativo de las técnicas utilizadas en un sistema de reconocimiento de hojas de planta. Revista Iberoamericana de Automática e Informática industrial 14 (1), 104-114. https://doi.org/10.1016/j.riai.2016.09.005Cheng, P., John, W., Zheng, W., 2002. Large structure health dynamic monito- ring using gps technology. In: FIG XXII International Congress, Washing- ton, DC USA. pp. 1-10.Dave, N., 2013. Feature extraction methods lpc, plp and mfcc in speech recog- nition. International journal for advance research in engineering and techno- logy 1 (6), 1-4.Di Sante, R., 2015. Fibre optic sensors for structural health monitoring of aircraft composite structures: Recent advances and applications. Sensors 15 (8), 18666-18713. https://www.mdpi.com/1424-8220/15/8/18666 , https://doi.org/10.3390/s150818666Doebling, S., Farrar, C., Prime, M., Shevitz, D., 5 1996. Damage identification and health monitoring of structural and mechanical systems from changes in their vibration characteristics: A literature review. Report. https://doi.org/10.2172/249299Feng, D., Feng, M. Q., 2017. Experimental validation of cost-effective vision- based structural health monitoring. Mechanical Systems and Signal Processing 88, 199-211. https://doi.org/10.1016/j.ymssp.2016.11.021Flores-Fuentes, W., López, M., Sergiyenko, O., González-Navarro, F. F., Rivera-Castillo, J., Hernandez-Balbuena, D., Rodríguez-Quiñonez, J., 2014. Combined application of power spectrum centroid and support vector ma- chines for measurement improvement in optical scanning systems. Signal Processing 98, 37-51. https://doi.org/10.1016/j.sigpro.2013.11.008Flores-Fuentes, W., Miranda-Vega, J. E., Rivas-López, M., Sergiyenko, O., Rodríguez-Quiñonez, J. C., Lindner, L., 2018. Comparison between different types of sensors used in the real operational environment based on optical scanning system. Sensors 18 (6). https://doi.org/10.3390/s18061684Jayalakshmi, T., Santhakumaran, A., 2011. Statistical normalization and back propagation for classification. International Journal of Computer Theory and Engineering 3 (1), 1793-8201. https://doi.org/10.7763/IJCTE.2011.V3.288Jo, H., Sim, S.-H., Tatkowski, A., Spencer Jr, B., Nelson, M. E., 2013. Feasibility of displacement monitoring using low-cost gps receivers. Structural Control and Health Monitoring 20 (9), 1240-1254. https://doi.org/10.1002/stc.1532Jung, H. K., Park, G., 2018. Integrating passive-and active-sensing techniques using an l-shaped sensor array for impact and damage localization. Journal of Intelligent Material Systems and Structures 29 (17), 3436-3443. https://doi.org/10.1177/1045389X17733059Lindner, L., Sergiyenko, O., Rodríguez-Quiñonez, J. C., Rivas-Lopez, M., Hernandez-Balbuena, D., Flores-Fuentes, W., Murrieta-Rico, F. N., Tyrsa, V., 2016. Mobile robot vision system using continuous laser scanning for industrial application. Industrial Robot: An International Journal. https://doi.org/10.1108/IR-01-2016-0048Mims, F. M., Dec 2000. Solar radiometer with light-emitting diodes as spectrally-selective detectors. Appl. Opt. 39 (34), 6517-6518. http://ao.osa.org/abstract.cfm?URI=ao-39-34-6517, https://doi.org/10.1364/AO.39.006517Miranda-Vega, J. E., Rivas-Lopez, M., Flores-Fuentes, W., Sergiyenko, O., Lindner, L., Rodríguez-Quiñonez, J. C., 2019. Implementación digital de filtros fir para la minimización del ruido óptico y optoelectrónico de un sistema de barrido óptico. Revista Iberoamericana de Automática e Informática industrial 16, 344-357. https://doi.org/10.4995/riai.2019.10210Rivera-Castillo, J., Flores-Fuentes, W., Rivas-Lopez, M., Sergiyenko, O., Gonzalez-Navarro, F. F., Rodríguez-Quiñonez, J. C., Hernandez-Balbuena, D., Lindner, L., Básaca-Preciado, L. C., 2017. Experimental image and range scanner datasets fusion in shm for displacement detection. Structural Control and Health Monitoring 24 (10), e1967. https://doi.org/10.1002/stc.1967Sergiyenko, O., Hernandez, W., Tyrsa, V., Cruz, L. F. 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    Digital Implementation of FIR Filters for the Minimize of Optical and Optoelectronic Noise of an Optical Scanning System.

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    [EN] There are different devices capable of discriminating optical and optoelectronic noise, however, the cost of its implementation and maintenance is expensive. This paper examines the possibility of digitally integrating Finite Impulse Response (FIR) filters into the transducer of an OSS systems to obtain better performance in a real operating environment. In this paper we propose the evaluation of the implementation of different FIR filters in different photo-sensors transducers, such as the Light-Dependent Resistor (LDR) and the Light Emitting Diode (LED).[ES] Existen distintos dispositivos capaces de discriminar el ruido óptico y optoelectrónico, sin embargo, el costo de su implementación y mantenimiento resulta costoso. Este trabajo examina la posibilidad de integrar digitalmente filtros de respuesta finita al impulso (en inglés, FIR; Finite Impulse Response) al transductor de un sistema OSS para obtener un mejor rendimiento en un ambiente real de operación. En este trabajo se propone la evaluación de la implementación de distintos filtros FIR en diferentes transductores fotosensores como lo son el resistor dependiente de luz (en inglés, LDR; Light-Dependent Resistor) y el diodo emisor de luz (en inglés, LED; Light-Emitting Diode).Miranda-Vega, JE.; Rivas-López, M.; Flores-Fuentes, W.; Sergiyenko, O.; Lindner, L.; Rodríguez-Quiñonez, JC. (2019). Implementación digital de filtros FIR para la minimización del ruido óptico y optoelectrónico de un sistema de barrido óptico. Revista Iberoamericana de Automática e Informática. 16(3):344-357. https://doi.org/10.4995/riai.2019.10210SWORD34435716
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