The Closest View of a Dwarf Galaxy: New Evidence on the Nature of the Canis Major over-density

We present a first deep colour-magnitude diagram of the putative central region (0.5 deg x 0.5 deg) of the Canis Major stellar over-density (l,b)=(240,-8) found by Martin et al. (2004), which has been proposed as the remnant of a dwarf satellite accreted onto the Milky Way on a near-equatorial orbit. We find a narrow (in apparent magnitude) main-sequence, extending 6 magnitudes below the turn-off to our limiting magnitude of B ~ 24.5 mag. This main sequence has very high constrast (>3) with respect to the thin/thick disk/halo background; its narrowness at brighter magnitudes clearly implies the presence of a distinct and possibly still bound stellar system. We derived the line-of-sight size (r_{1/2}) of this system based on the B-band width of the lower main sequence, obtaining 0.94 +/- 0.18 (random) +/- 0.18 (systematic) kpc. That size matches a model prediction for the main body of the parent galaxy of the Monoceros tidal stream. The high density contrast and limited spatial extent in the radial direction are very hard to reconcile with the alternative explanation put forward to explain the Canis Major stellar-overdensity: a flared or warped Galactic disk viewed in projection (Momamy et al. 2004). We also derived a central surface brightness of mu_{V,0}= 23.3 +/- 0.1 mag arcsec^{-2} and an absolute magnitude of M_{V}=-14.5 +/- 0.1 mag. These values place the Canis Major object in the category of dwarf galaxy in the the L_{V}--size and M_V - mu_{V} planes for such objects. However, like the Sagittarius dwarf, it is an outlier in the[Fe/H] -M_V plane in the sense that it is too metal rich for its estimated absolute magnitude. This suggests that the main mechanism driving its recent and current star formation history (possibly tidal stripping) is different to that of isolated dwarfs.Comment: Accepted version in Astrophysical Journal Part 1. Include a new figure, some changes in the derive CMa dwarf properties, main conclusions unchanged. 5 Pages, 3 figures, 2 tables. High resolution version can be downloaded from:ftp://ftp.iaa.csic.es/pub/ddelgado/canismajor.ps.g

Biotic and abiotic controls on carbon storage in aggregates in calcareous alpine and prealpine grassland soils

Alpine and prealpine grasslands provide various ecosystem services and are hotspots for the storage of soil organic C (SOC) in Central Europe. Yet, information about aggregate-related SOC storage and its controlling factors in alpine and prealpine grassland soils is limited. In this study, the SOC distribution according to the aggregate size classes large macroaggregates (> 2000 μm), small macroaggregates (250–2000 μm), microaggregates (63–250 μm), and silt-/clay-sized particles (< 63 μm) was studied in grassland soils along an elevation gradient in the Northern Limestone Alps of Germany. This was accompanied by an analysis of earthworm abundance and biomass according to different ecological niches. The SOC and N stocks increased with elevation and were associated with relatively high proportions of water-stable macroaggregates due to high contents of exchangeable Ca$^{2+}$ and Mg$^{2+}$. At lower elevations, earthworms appeared to act as catalyzers for a higher microaggregate formation. Thus, SOC stabilization by aggregate formation in the studied soils is a result of a joined interaction of organic matter and Ca$^{2+}$ as binding agents for soil aggregates (higher elevations), and the earthworms that act as promoters of aggregate formation through the secretion of biogenic carbonates (low elevation). Our study highlights the importance of aggregate-related factors as potential indices to evaluate the SOC storage potential in other mountainous grassland soils

Taking Census of Massive, Star-Forming Galaxies formed <1 Gyr After the Big Bang

Two decades of effort have been poured into both single-dish and interferometric millimeter-wave surveys of the sky to infer the volume density of dusty star-forming galaxies (DSFGs, with SFR>100M⊙ yr^(−1)) over cosmic time. Though obscured galaxies dominate cosmic star-formation near its peak at z∼2, the contribution of such heavily obscured galaxies to cosmic star-formation is unknown beyond z∼2.5 in contrast to the well-studied population of Lyman-break galaxies (LBGs) studied through deep, space- and ground-based pencil beam surveys in the near-infrared. Unlocking the volume density of DSFGs beyond z>3, particularly within the first 1 Gyr after the Big Bang is critical to resolving key open questions about early Universe galaxy formation: (1) What is the integrated star-formation rate density of the Universe in the first few Gyr and how is it distributed among low-mass galaxies (e.g. Lyman-break galaxies) and high-mass galaxies (e.g. DSFGs and quasar host galaxies)? (2) How and where do the first massive galaxies assemble? (3) What can the most extreme DSFGs teach us about the mechanisms of dust production (e.g. supernovae, AGB stars, grain growth in the ISM) <1 Gyr after the Big Bang? We summarize the types of observations needed in the next decade to address these questions

Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

The HERA-B collaboration has studied the production of charmonium and open charm states in collisions of 920 GeV protons with wire targets of different materials. The acceptance of the HERA-B spectrometer covers negative values of xF up to xF=-0.3 and a broad range in transverse momentum from 0.0 to 4.8 GeV/c. The studies presented in this paper include J/psi differential distributions and the suppression of J/psi production in nuclear media. Furthermore, production cross sections and cross section ratios for open charm mesons are discussed.Comment: 5 pages, 9 figures, to be published in the proceedings of the 6th International Conference on Hyperons, Charm & Beauty Hadrons (BEACH04), Chicago, IL, June 27 - July 3, 200

Un caso de seroconversión del H.I.V. en una trabajadora del sexo portadora asintomática

NAN

The IARC perspective on cervical cancer screening

In May 2018, the World Health Organization (WHO) called for a global initiative to eliminate cervical cancer as a public health problem. To achieve this goal, global scale-up of effective vaccination against the human papillomavirus (HPV) as well as screening for and treatment of cervical cancer are required. Cervical cancer screening was evaluated in 2005 by the International Agency for Research on Cancer (IARC) Handbooks program,1 and a reevaluation was deemed to be timely given the major advances in the field since then. The new handbook provides updated evaluations of the effectiveness of screening methods, which were used as a basis for the update of the WHO Guideline for Screening and Treatment of Cervical Pre-cancer Lesions for Cervical Cancer Prevention.2 We convened an IARC Working Group of 27 scientists from 20 countries to assess the evidence on the current approaches to and technologies used in cervical cancer screening with the use of the newly updated Handbooks Preamble3 (Fig. 1) and Table 1).Fil: Bouvard, Véronique. International Agency For Research On Cancer; FranciaFil: Wentzensen, Nicolas. National Cancer Institute; Estados UnidosFil: Mackie, Anne. Public Health England; Reino UnidoFil: Berkhof, Johannes. University of Amsterdam; Países BajosFil: Brotherton, Julia. VCS Foundation; Australia. University of Melbourne; AustraliaFil: Giorgi Rossi, Paolo. Azienda Unità Sanitaria Locale Di Reggio Emilia; ItaliaFil: Kupets, Rachel. University of Toronto; CanadáFil: Smith, Robert. American Cancer Society; Estados UnidosFil: Arrossi, Silvina. Centro de Estudios de Estado y Sociedad; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bendahhou, Karima. Casablanca Cancer Registry; MarruecosFil: Canfell, Karen. The University Of Sydney; AustraliaFil: Chirenje, Z. Mike. University Of Zimbabwe; ZimbabueFil: Chung, Michael H.. University of Emory; Estados UnidosFil: del Pino, Marta. Hospital Clinico de Barcelona; EspañaFil: de Sanjosé, Silvia. Program for Appropriate Technology in Health; Estados UnidosFil: Elfström, Miriam. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Franco, Eduardo L.. McGill University; CanadáFil: Hamashima, Chisato. Teikyo University; JapónFil: Hamers, Françoise F.. French National Public Health Agency; FranciaFil: Herrington, C. Simon. University of Edinburgh; Reino UnidoFil: Murillo, Raúl. Hospital Universitario San Ignacio; ColombiaFil: Sangrajrang, Suleeporn. National Cancer Institute; TailandiaFil: Sankaranarayanan, Rengaswamy. Research Triangle Institute; Estados UnidosFil: Saraiya, Mona. Centers for Disease Control and Prevention; Estados UnidosFil: Schiffman, Mark. National Cancer Institute; Estados UnidosFil: Zhao, Fanghui. Chinese Academy of Medical Sciences & Peking Union Medical College; ChinaFil: Arbyn, Marc. Sciensano; BélgicaFil: Prendiville, Walter. International Agency For Research On Cancer; FranciaFil: Indave Ruiz, Blanca I.. International Agency For Research On Cancer; FranciaFil: Mosquera Metcalfe, Isabel. International Agency For Research On Cancer; FranciaFil: Lauby Secretan, Béatrice. International Agency For Research On Cancer; Franci

Control of star formation by supersonic turbulence

Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that stellar birth is primarily controlled by the interplay between gravity and magnetostatic support, modulated by ambipolar diffusion. Recently, however, both observational and numerical work has begun to suggest that support by supersonic turbulence rather than magnetic fields controls star formation. In this review we outline a new theory of star formation relying on the control by turbulence. We demonstrate that although supersonic turbulence can provide global support, it nevertheless produces density enhancements that allow local collapse. Inefficient, isolated star formation is a hallmark of turbulent support, while efficient, clustered star formation occurs in its absence. The consequences of this theory are then explored for both local star formation and galactic scale star formation. (ABSTRACT ABBREVIATED)Comment: Invited review for "Reviews of Modern Physics", 87 pages including 28 figures, in pres

Amplified melt and flow of the Greenland ice sheet driven by late-summer cyclonic rainfall

Intense rainfall events significantly affect Alpine and Alaskan glaciers through enhanced melting, ice-flow acceleration and subglacial sediment erosion, yet their impact on the Greenland ice sheet has not been assessed. Here we present measurements of ice velocity, subglacial water pressure and meteorological variables from the western margin of the Greenland ice sheet during a week of warm, wet cyclonic weather in late August and early September 2011. We find that extreme surface runoff from melt and rainfall led to a widespread acceleration in ice flow that extended 140 km into the ice-sheet interior. We suggest that the late-season timing was critical in promoting rapid runoff across an extensive bare ice surface that overwhelmed a subglacial hydrological system in transition to a less-efficient winter mode. Reanalysis data reveal that similar cyclonic weather conditions prevailed across southern and western Greenland during this time, and we observe a corresponding ice-flow response at all land- and marine-terminating glaciers in these regions for which data are available. Given that the advection of warm, moist air masses and rainfall over Greenland is expected to become more frequent in the coming decades, our findings portend a previously unforeseen vulnerability of the Greenland ice sheet to climate change