Stellar Motion around Spiral Arms: Gaia Mock Data

We compare the stellar motion around a spiral arm created in two different scenarios, transient/co-rotating spiral arms and density-wave-like spiral arms. We generate Gaia mock data from snapshots of the simulations following these two scenarios using our stellar population code, SNAPDRAGONS, which takes into account dust extinction and the expected Gaia errors. We compare the observed rotation velocity around a spiral arm similar in position to the Perseus arm, and find that there is a clear difference in the velocity features around the spiral arm between the co-rotating spiral arm and the density-wave-like spiral arm. Our result demonstrates that the volume and accuracy of the Gaia data are sufficient to clearly distinguish these two scenarios of the spiral arms.Comment: 5 pages, 1 figure, to appear in the proceedings of "The Milky Way Unravelled by Gaia: GREAT Science from the Gaia Data Releases", Barcelona, 1-5 December 2014, eds. N. Walton, F. Figueras, C. Soubira

Stellar Motion around Spiral Arms: Gaia Mock Data

We compare the stellar motion around a spiral arm created in two different scenarios, transient/co-rotating spiral arms and density-wave-like spiral arms. We generate Gaia mock data from snapshots of the simulations following these two scenarios using our stellar population code, SNAPDRAGONS, which takes into account dust extinction and the expected Gaia errors. We compare the observed rotation velocity around a spiral arm similar in position to the Perseus arm, and find that there is a clear difference in the velocity features around the spiral arm between the co-rotating spiral arm and the density-wave-like spiral arm. Our result demonstrates that the volume and accuracy of the Gaia data are sufficient to clearly distinguish these two scenarios of the spiral arms

Range of reproduction number estimates for COVID-19 spread

To monitor local and global COVID-19 outbreaks, and to plan containment measures, accessible and comprehensible decision-making tools need to be based on the growth rates of new confirmed infections, hospitalization or case fatality rates. Growth rates of new cases form the empirical basis for estimates of a variety of reproduction numbers, dimensionless numbers whose value, when larger than unity, describes surging infections and generally worsening epidemiological conditions. Typically, these determinations rely on noisy or incomplete data gained over limited periods of time, and on many parameters to estimate. This paper examines how estimates from data and models of time-evolving reproduction numbers of national COVID-19 infection spread change by using different techniques and assumptions. Given the importance acquired by reproduction numbers as diagnostic tools, assessing their range of possible variations obtainable from the same epidemiological data is relevant. We compute control reproduction numbers from Swiss and Italian COVID-19 time series adopting both data convolution (renewal equation) and a SEIR-type model. Within these two paradigms we run a comparative analysis of the possible inferences obtained through approximations of the distributions typically used to describe serial intervals, generation, latency and incubation times, and the delays between onset of symptoms and notification. Our results suggest that estimates of reproduction numbers under these different assumptions may show significant temporal differences, while the actual variability range of computed values is rather small

Theory of Stellar Population Synthesis with an application to N-Body simulations

Aims. We present here a new theoretical approach to population synthesis. The aim is to predict colour magnitude diagrams (CMDs) for huge numbers of stars. With this method we generate synthetic CMDs for N-body simulations of galaxies. Sophisticated hydrodynamic N-body models of galaxies require equal quality simulations of the photometric properties of their stellar content. The only prerequisite for the method to work is very little information on the star formation and chemical enrichment histories, i.e. the age and metallicity of all star-particles as a function of time. The method takes into account the gap between the mass of real stars and that of the star-particles in N-body simulations, which best correspond to the mass of star clusters with different age and metallicity, i.e. a manifold of single stellar sopulations (SSP). Methods. The theory extends the concept of SSP to include the phase-space (position and velocity) of each star. Furthermore, it accelerates the building up of simulated CMD by using a database of theoretical SSPs that extends to all ages and metallicities of interest. Finally, it uses the concept of distribution functions to build up the CMD. The technique is independent of the mass resolution and the way the N-body simulation has been calculated. This allows us to generate CMDs for simulated stellar systems of any kind: from open clusters to globular clusters, dwarf galaxies, or spiral and elliptical galaxies. Results. The new theory is applied to an N-body simulation of a disc galaxy to test its performance and highlight its flexibility.Comment: accepted for publication in A&

Lactancia materna y hospital amigo del niño: una necesidad en la provincia de Corrientes

La Lactancia Materna (LM) es la mejor forma de alimentar y criar a un niño, no obstante su práctica se ha reducido paulatinamente. La Organización Mundial de la Salud (OMS) junto a UNICEF ha propuesto la “Iniciativa Hospital Amigo” (IHAN), con objetivos tendientes a restablecer y mejorar dicha práctica. Objetivos: Determinar las características socio-demográficas de las madres que asisten a un hospital de referencia de la Provincia de Corrientes; Identificar la influencia del nivel de instrucción materno con la posibilidad de mantener la LM exclusiva; y Evaluar la necesidad de la IHAN en nuestra Provincia. Materiales y Métodos: Se realizó estudio observacional descriptivo de corte transversal, a través de encuestas a 146 madres de la Maternidad del Hospital “Dr. José R. Vidal” en el período de Agosto a Diciembre del 2010. Resultados: El 79,5% estaba entre los 15 y 30 años; 53,4% se encontraban separadas o en concubinato, el 52,7% tenía un nivel de instrucción moderado; 97,9% consideraba importante amamantar, el 78,1% daría pecho exclusivo; 45,2% daría LM hasta el año; el 81,5% no trabaja fuera del hogar; 40,4% recibió información del equipo de salud; el 89% asistiría a un centro de apoyo de lactancia. Discusión: El IHAN, es una necesidad en nuestra región; lo que posibilitaría que el deseo expresado por las madres de amamantar más allá de los 6 meses y de contar con apoyo asistencial, sea posible.Introduction: Breastfeeding (BF) is the best way to feed and raise a child, however the practice has declined gradually. The World Health Organization (WHO) together with UNICEF has proposed the "Baby Friendly Hospital Initiative" (BFHI), with objectives aimed at restoring and improving the practice. Objectives: To determine the sociodemographic characteristics of mothers attending a referral hospital in the province of Corrientes, Identify the influence of mother's education level with the ability to maintain exclusive BF, and Evaluate the need for the BFHI in our province. Materials and Methods: Descriptive study of cross-section through surveys of 146 mothers in the Maternity Hospital "Dr. José R. Vidal" in the period from August to December 2010. Results: 79.5% were between 15 and 30 years, 53.4% were separated or cohabiting, 52.7% had a moderate level of education, 97.9% considered it important to breastfeed, 78.1% would exclusively breastfed, 45.2% would give for a year BF, 81.5% do not work outside the home, 40.4% received information from the health team, 89% would attend a breastfeeding support center. Discussion: The BFHI is a necessity in our region, that would allow the desire of mothers to breastfeed beyond 6 months and to have care support.Fil: Niello, Esteban N.. Universidad Nacional del Nordeste; ArgentinaFil: Palma Pérez, Ricardo D.. Universidad Nacional del Nordeste; ArgentinaFil: Pasetto, Raúl I.. Universidad Nacional del Nordeste; ArgentinaFil: Horna, Maria Eugenia. Universidad Nacional del Nordeste. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hidalgo, Susana. Universidad Nacional del Nordeste; Argentin

A stratified compartmental model for the transmission of Sparicotyle chrysophrii (Platyhelminthes: Monogenea) in gilthead seabream (Sparus aurata) fish farms †

The rapid development of intensive fish farming has been associated with the spreading of infectious diseases, pathogens and parasites. One such parasite is Sparicotyle chrysophrii (Platyhelminthes: Monogenea), which commonly infects cultured gilthead seabream (Sparus aurata)-a vital species in Mediterranean aquaculture. The parasite attaches to fish gills and can cause epizootics in sea cages with relevant consequences for fish health and associated economic losses for fish farmers. In this study, a novel stratified compartmental epidemiological model of S. chrysophrii transmission was developed and analysed. The model accounts for the temporal progression of the number of juvenile and adult parasites attached to each fish, as well as the abundance of eggs and oncomiracidia. We applied the model to data collected in a seabream farm, where the fish population and the number of adult parasites attached to fish gills were closely monitored in six different cages for 10 months. The model successfully replicated the temporal dynamics of the distribution of the parasite abundance within fish hosts and simulated the effects of environmental factors, such as water temperature, on the transmission dynamics. The findings highlight the potential of modelling tools for farming management, aiding in the prevention and control of S. chrysophrii infections in Mediterranean aquaculture