The global mass function of M15

Data obtained with the NICMOS instrument on board the Hubble Space Telescope (HST) have been used to determine the H-band luminosity function (LF) and mass function (MF) of three stellar fields in the globular cluster M15, located ~7' from the cluster centre. The data confirm that the cluster MF has a characteristic mass of ~0.3 Msolar, as obtained by Paresce & De Marchi (2000) for a stellar field at 4.6' from the centre. By combining the present data with those published by other authors for various radial distances (near the centre, at 20" and at 4.6'), we have studied the radial variation of the LF due to the effects of mass segregation and derived the global mass function (GMF) using the Michie-King approach. The model that simultaneously best fits the LF at various locations, the surface brightness profile and the velocity dispersion profile suggests that the GMF should resemble a segmented power-law with the following indices: x ~ 0.8 for stars more massive than 0.8 Msolar, x ~ 0.9 for 0.3 - 0.8 Msolar and x ~ -2.2 at smaller masses (Salpeter's IMF would have x=1.35). The best fitting model also suggests that the cluster mass is ~5.4 10^5 Msolar and that the mass-to-light ratio is on average M/L_V ~ 2.1, with M/L_V ~ 3.7 in the core. A large amount of mass (~ 44 %) is found in the cluster core in the form of stellar heavy remnants, which may be sufficient to explain the mass segregation in M15 without invoking the presence of an intermediate-mass black hole.Comment: 12 pages, 10 figures, accepted for publication in A&

Genetic parameters for milk mineral content and acidity predicted by mid-infrared spectroscopy in Holstein–Friesian cows

peer-reviewedThis article was first published in animal, Volume 9, Issue 05, May 2015, pp 775-780 © The Animal Consortium 2015The aim of the present study was to estimate genetic parameters for calcium (Ca), phosphorus (P) and titratable acidity (TA) in bovine milk predicted by mid-IR spectroscopy (MIRS). Data consisted of 2458 Italian Holstein−Friesian cows sampled once in 220 farms. Information per sample on protein and fat percentage, pH and somatic cell count, as well as test-day milk yield, was also available. (Co)variance components were estimated using univariate and bivariate animal linear mixed models. Fixed effects considered in the analyses were herd of sampling, parity, lactation stage and a two-way interaction between parity and lactation stage; an additive genetic and residual term were included in the models as random effects. Estimates of heritability for Ca, P and TA were 0.10, 0.12 and 0.26, respectively. Positive moderate to strong phenotypic correlations (0.33 to 0.82) existed between Ca, P and TA, whereas phenotypic weak to moderate correlations (0.00 to 0.45) existed between these traits with both milk quality and yield. Moderate to strong genetic correlations (0.28 to 0.92) existed between Ca, P and TA, and between these predicted traits with both fat and protein percentage (0.35 to 0.91). The existence of heritable genetic variation for Ca, P and TA, coupled with the potential to predict these components for routine cow milk testing, imply that genetic gain in these traits is indeed possible

U.S. day of the dead : fusing Spanish, indigeous and U.S. cultures to communicate new messages

The largest Hispanic celebration in the U.S., el Día de los Muertos, has both Spanish and Indigenous American roots. Largely unknown in the US prior to the 1970s, it was adopted by Mexican American artists as an emblematic symbol of the Chicano Movement. It is now part of the educational curricula of many U.S. schools and universities and is one of the most popular annual exhibits in art galleries and museums. Receiving prominent media coverage because of its colorful rituals, the celebration in its new socio-political context honors the growing demographic of Latinos in the U.S. and encourages moral reflection on issues of political importance. Many Day of the Dead activities honor popular Latino icons (i.e. artist Frida Kahlo, labor union organizer César Chávez, salsa star Celia Cruz) and a significant number draw attention to sociopolitical causes of death affecting the Latino community (i.e. gang violence, war, labor exploitation). Through public altars, art installations, street processions and vigils commemorating the dead, participants contest the privatization of sadness and frustration experienced by sectors of U.S. society disproportionately affected by an unnecessary loss of life. At the same time, the celebration is a unique medium for teaching about Latino identities and histories. Based on ethnographic observation of more than 100 Day of the Dead events in the United States over a 10 year period, as well as interviews with 78 Chicano artists and other participants, this paper will discuss the emergence of the celebration in the US and the changes in meaning that have occurred as the festivities have migrated to new geographical and socio-political contexts.La fiesta hispánica más grande de los Estados Unidos, el Día de los Muertos, tiene raíces indígenas y españolas. Básicamente desconocida en los EEUU hasta la década de los años setenta, la fiesta fue adoptada por artistas México-Americanos como un símbolo emblemático del movimiento chicano. Ahora forma parte del currículum educacional de muchas escuelas y universidades norteamericanas y es una de las exposiciones más populares en museos y galerías de arte. La celebración recibe amplia cobertura de los medios de comunicación dado a sus rituales coloridos y exóticos. La celebración en su nuevo contexto político y social hace honor a la creciente presencia latina en los EEUU y alienta la reflexión moral sobre cuestiones de importancia política. Muchas actividades del Día de los Muertos están dedicadas a iconos populares latinos (como por ejemplo Frida Kahlo, el sindicalista César Chávez, la cantante de salsa Celia Cruz) como también a recalcar causas de muerte y sufrimiento que afectan a la comunidad latina (violencia de las pandillas, la guerra, explotación laboral). A través de la construcción de altares públicos, instalaciones artísticas, marchas, y vigilias honrando a los difuntos, los participantes enfrentan la privatización de la tristeza y la frustración experimentada por los sectores de la sociedad americana afectada desproporcionalmente por la muerte innecesaria. Al mismo tiempo, la celebración es un medio único para enseñar sobre la historia e identidad latina. Basado en la observación etnográfica de más de cien eventos de Día de los Muertos en los EEUU a través de una década, como también entrevistas a 78 artistas chicanos y otros participantes, esta monografía discute la llegada de la celebración a los EEUU y los cambios de significado que han ocurrido al cambiar las festividades su geografía y contexto socio político

U.S. day of the dead : fusing Spanish, indigeous and U.S. cultures to communicate new messages

The largest Hispanic celebration in the U.S., el Día de los Muertos, has both Spanish and Indigenous American roots. Largely unknown in the US prior to the 1970s, it was adopted by Mexican American artists as an emblematic symbol of the Chicano Movement. It is now part of the educational curricula of many U.S. schools and universities and is one of the most popular annual exhibits in art galleries and museums. Receiving prominent media coverage because of its colorful rituals, the celebration in its new socio-political context honors the growing demographic of Latinos in the U.S. and encourages moral reflection on issues of political importance. Many Day of the Dead activities honor popular Latino icons (i.e. artist Frida Kahlo, labor union organizer César Chávez, salsa star Celia Cruz) and a significant number draw attention to sociopolitical causes of death affecting the Latino community (i.e. gang violence, war, labor exploitation). Through public altars, art installations, street processions and vigils commemorating the dead, participants contest the privatization of sadness and frustration experienced by sectors of U.S. society disproportionately affected by an unnecessary loss of life. At the same time, the celebration is a unique medium for teaching about Latino identities and histories. Based on ethnographic observation of more than 100 Day of the Dead events in the United States over a 10 year period, as well as interviews with 78 Chicano artists and other participants, this paper will discuss the emergence of the celebration in the US and the changes in meaning that have occurred as the festivities have migrated to new geographical and socio-political contexts.La fiesta hispánica más grande de los Estados Unidos, el Día de los Muertos, tiene raíces indígenas y españolas. Básicamente desconocida en los EEUU hasta la década de los años setenta, la fiesta fue adoptada por artistas México-Americanos como un símbolo emblemático del movimiento chicano. Ahora forma parte del currículum educacional de muchas escuelas y universidades norteamericanas y es una de las exposiciones más populares en museos y galerías de arte. La celebración recibe amplia cobertura de los medios de comunicación dado a sus rituales coloridos y exóticos. La celebración en su nuevo contexto político y social hace honor a la creciente presencia latina en los EEUU y alienta la reflexión moral sobre cuestiones de importancia política. Muchas actividades del Día de los Muertos están dedicadas a iconos populares latinos (como por ejemplo Frida Kahlo, el sindicalista César Chávez, la cantante de salsa Celia Cruz) como también a recalcar causas de muerte y sufrimiento que afectan a la comunidad latina (violencia de las pandillas, la guerra, explotación laboral). A través de la construcción de altares públicos, instalaciones artísticas, marchas, y vigilias honrando a los difuntos, los participantes enfrentan la privatización de la tristeza y la frustración experimentada por los sectores de la sociedad americana afectada desproporcionalmente por la muerte innecesaria. Al mismo tiempo, la celebración es un medio único para enseñar sobre la historia e identidad latina. Basado en la observación etnográfica de más de cien eventos de Día de los Muertos en los EEUU a través de una década, como también entrevistas a 78 artistas chicanos y otros participantes, esta monografía discute la llegada de la celebración a los EEUU y los cambios de significado que han ocurrido al cambiar las festividades su geografía y contexto socio político

Heating of near-Earth objects and meteoroids due to close approaches to the Sun

It is known that near-Earth objects (NEOs) during their orbital evolution may often undergo close approaches to the Sun. Indeed it is estimated that up to ~70% of them end their orbital evolution colliding with the Sun. Starting from the present orbital properties, it is possible to compute the most likely past evolution for every NEO, and to trace its distance from the Sun. We find that a large fraction of the population may have experienced in the past frequent close approaches, and thus, as a consequence, a considerable Sun-driven heating, not trivially correlated to the present orbits. The detailed dynamical behaviour, the rotational and the thermal properties of NEOs determine the exact amount of the resulting heating due to the Sun. In the present paper we discuss the general features of the process, providing estimates of the surface temperature reached by NEOs during their evolution. Moreover, we investigate the effects of this process on meteor-size bodies, analyzing possible differences with the NEO population. We also discuss some possible effects of the heating which can be observed through remote sensing by ground-based surveys or space missions.Comment: 8 pages, 5 figures, accepted by MNRA

Late movement of basin-edge lobate scarps on Mercury

Basin-edge lobate scarps are a sub-type of tectonic shortening structure on the surface of Mercury that have formed at the edge of volcanic units that fill or partly fill impact basins. We have performed a global survey of these features and find that they are widespread in basins across the planet. We obtained model ages from crater size–frequency distribution analysis for a subset of our surveyed basins, for both the smooth plains infill and for the last resolvable tectonic activity on the associated basin-edge scarps. Our results indicate that some of these lobate scarps were still accumulating strain in the late Mansurian (approximately 1 Ga). From a photogeological assessment, we find that the orientations of these basin-edge lobate scarps are similar to those reported for the global population of lobate scarps in earlier studies, appearing to align ∼north–south at low latitudes and ∼east–west at higher latitudes. However, reassessing these landforms’ orientation with artificially illuminated topographic data does not allow us to rule out the effect of illumination bias. We propose that these landforms, the result of crustal shortening in response to global contraction, formed along the interface between the basin floor and the smooth plains unit, which acted as a mechanical discontinuity along which shortening strains were concentrated

The Cratering History of Asteroid (2867) Steins

The cratering history of main belt asteroid (2867) Steins has been investigated using OSIRIS imagery acquired during the Rosetta flyby that took place on the 5th of September 2008. For this purpose, we applied current models describing the formation and evolution of main belt asteroids, that provide the rate and velocity distributions of impactors. These models coupled with appropriate crater scaling laws, allow the cratering history to be estimated. Hence, we derive Steins' cratering retention age, namely the time lapsed since its formation or global surface reset. We also investigate the influence of various factors -like bulk structure and crater erasing- on the estimated age, which spans from a few hundred Myrs to more than 1Gyr, depending on the adopted scaling law and asteroid physical parameters. Moreover, a marked lack of craters smaller than about 0.6km has been found and interpreted as a result of a peculiar evolution of Steins cratering record, possibly related either to the formation of the 2.1km wide impact crater near the south pole or to YORP reshaping.Comment: Accepted by Planetary and Space Scienc

Measurements of debris flow velocity through cross-correlation of instrumentation data

International audienceDetection of debris flow occurrence can be efficiently obtained through different types of sensors. A pair of ultrasonic sensors placed at a known distance from each other along a torrent have been used as a method to obtain mean front velocity of debris-flows, in addition to their use as detectors of debris flow occurrence. Also seismic and acoustic sensors have been employed to measure debris-flow front velocity and discharge in the same manner. In order to obtain velocity measurements, however, these methods require the presence of a well identifiable and defined main front in the debris flow wave. The time lag between the recordings of the front of the wave at two consecutive stations allows an estimation of its mean velocity. When a well-defined front is not present and no recurrent feature can be found along the wave, the measurement of velocity may prove difficult. The cross-correlation technique may help identifying the mean velocity of the flow in such cases. In fact, cross correlation allows to determine the mean time lag elapsed between the recording of two sets of data of the same event at different positions. This technique may be also used to measure velocity using signals coming from different types of sensors, for instance where a ground vibration detector has been placed along a torrent where an ultrasonic sensor was already present or viceversa. An application has been made using field data recorded through seismic and ultrasonic sensors in a small instrumented catchment in the Italian Alps (Moscardo Torrent)