8,081 research outputs found

    Tracing out the Northern Tidal Stream of the Sagittarius Dwarf Spheoridal Galaxy

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    The main aim of this paper is to report two new detections of tidal debris in the northern stream of the Sagittarius dwarf galaxy located at 45 arcdeg and 55 arcdeg from the center of galaxy. Our observational approach is based on deep color-magnitude diagrams, that provides accurate distances, surface brightness and the properties of stellar population of the studied region of this tidal stream. The derived distances for these tidal debris wraps are 45 kpc and 54 kpc respectively.We also confirm these detections with numerical simulations of the Sagittarius dwarf plus the Milky Way. The model reproduces the present position and velocity of the Sagittarius main body and presents a long tidal stream formed by tidal interaction with the Milky Way potential. This model is also in good agreement with the available observations of the Sagittarius tidal stream. We also present a method for estimating the shape of the Milky Way halo potential using numerical simulations. From our simulations we obtain an oblateness of the Milky Way dark halo potential of 0.85, using the current database of distances and radial velocities of the Sagittarius tidal stream. The color-magnitude diagram of the apocenter of Sagittarius shows that this region of the stream shares the complex star formation history observed in the main body of the galaxy. We present the first evidence for a gradient in the stellar population along the stream, possibly correlated with its different pericenter passages. (abridged)Comment: 43 pages (including 15 figures; for high resolution color figures, please contact [email protected]). Submitted to Ap

    Sagittarius Tidal Debris 90 kpc from the Galactic Center

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    A new overdensity of A-colored stars in distant parts of the Milky Way's stellar halo, at a dereddened SDSS magnitude of g_0 = 20.3, is presented. Identification of associated variable RR Lyrae candidates supports the claim that these are blue horizontal branch stars. The inferred distance of these stars from the Galactic center is 90 kpc, assuming the absolute magnitude of these stars is M_g_0 = 0.7 and that the Sun is 8.5 kpc from the Galactic center. The new tidal debris is within 10 kpc of same plane as other confirmed tidal debris from the disruption of the Sagittarius dwarf galaxy, and could be associated with the trailing tidal arm. Distances to the Sagittarius stream estimated from M stars are about 13% smaller than our inferred distances. The tidal debris has a width of at least 10 degrees, and is traced for more than 20 degrees across the sky. The globular cluster NGC 2419 is located within the detected tidal debris, and may also have once been associated with the Sagittarius dwarf galaxy.Comment: 4 figures, ApJL in pres

    Targeting VIP and PACAP receptor signalling: new therapeutic strategies in multiple sclerosis

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    MS (multiple sclerosis) is a chronic autoimmune and neurodegenerative pathology of the CNS (central nervous system) affecting approx. 2.5 million people worldwide. Current and emerging DMDs (disease-modifying drugs) predominantly target the immune system. These therapeutic agents slow progression and reduce severity at early stages of MS, but show little activity on the neurodegenerative component of the disease. As the latter determines permanent disability, there is a critical need to pursue alternative modalities. VIP (vasoactive intestinal peptide) and PACAP (pituitary adenylate cyclase-activating peptide) have potent anti-inflammatory and neuroprotective actions, and have shown significant activity in animal inflammatory disease models including the EAE (experimental autoimmune encephalomyelitis) MS model. Thus, their receptors have become candidate targets for inflammatory diseases. Here, we will discuss the immunomodulatory and neuroprotective actions of VIP and PACAP and their signalling pathways, and then extensively review the structure–activity relationship data and biophysical interaction studies of these peptides with their cognate receptors

    High-order Harmonic Generation and Dynamic Localization in a driven two-level system, a non-perturbative solution using the Floquet-Green formalism

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    We apply the Floquet-Green operator formalism to the case of a harmonically-driven two-level system. We derive exact expressions for the quasi-energies and the components of the Floquet eigenstates with the use of continued fractions. We study the avoided crossings structure of the quasi-energies as a function of the strength of the driving field and give an interpretation in terms of resonant multi-photon processes. From the Floquet eigenstates we obtain the time-evolution operator. Using this operator we study Dynamic Localization and High-order Harmonic Generation in the non-perturbative regime

    Efecto de la presencia de flóculos sobre el crecimiento en juveniles de camarones blancos del pacifico litopenaeus vannamei en sistemas intensivos en condiciones experimentales

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    To determine the effect of the floc on the growth of juvenile shrimp Litopenaeus vannamei in intensive systems under experimental conditions. Materials and methods. To determine which treatment reached the highest, physical and chemical factors were measured: dissolved oxygen and temperature; and population parameters Accumulated Growth, Survival and Feed Conversion Factor. Collecting these data for 25 days where the Litopenaeus vannamei shrimp had an initial weight of 1.8 gr in both treatments. Results. According to the results obtained in the experiment, the commercial feed + floc treatment obtained a final growth of 5.35, on the other hand, the treatment with only commercial feed reached 4.9 gr. Conclution. The commercial feed + floc treatment gained larger size and biomass in less time because the floc application managed to provide more nutrients to the applied diet and in this way the shrimp took advantage of this supply, this natural food being the primary food source. while in the treatment without floc, lower biomass was obtained since no substitute was added to this treatment, only commercial feed, when performing the statistical analyzes it was found that p<0.05, which indicates that there was a significant difference, substantiating that with the use of floc growth of shrimp Litopenaeus vannamei is higher.  Determinar el efecto el flóculo sobre el crecimiento en juveniles de camarones juveniles Litopenaeus vannamei en sistemas intensivos en condiciones experimentales. Materiales y métodos.Para determinar cuál tratamiento alcanzó un mayor se midieron factores físicos y químicos: Oxígeno disuelto y Temperatura; y parámetros poblacionales Crecimiento acumulado, Sobrevivencia y Factor de Conversión Alimenticia. Recolectando estos datos durante 25 dias donde los camarones Litopenaeus vannamei tuvieron un peso inicial de 1.8 gr en ambos tratamientos. Resultados. Según los resultados obtenidos en el experimento, el tratamiento de alimento comercia + flóculo obtuvo un crecimiento final de 5.35 por otro lado el tratamiento solamente con alimento comercial alcanzó 4.9 gr. Conclusión. El tratamiento de alimento comercial + flóculo gano mayor tamaño y biomasa en menor tiempo debido a que la aplicación de flóculo logró aportar más nutrientes a la dieta aplicada y de esta forma los camarones aprovecharon este suministro siendo este alimento natural el primordial como fuente de alimentación, mientras que en el tratamiento sin flóculo se obtuvo menor biomasa ya a que este tratamiento no se le agrego ningún suplente solamente alimento comercial, al realizar los análisis estadísticos se encontró que p<0.05 lo que indica que hubo diferencia significativa fundamentando que con el uso de flóculos el crecimiento de los camarones Litopenaeus vannamei es mayor

    Bayesian analysis of the association between casein complex haplotype variants and milk yield, composition, and curve shape parameters in murciano-granadina goats

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    Considering casein haplotype variants rather than SNPs may maximize the understanding of heritable mechanisms and their implication on the expression of functional traits related to milk production. Effects of casein complex haplotypes on milk yield, milk composition, and curve shape parameters were used using a Bayesian inference for ANOVA. We identified 48 single nucleotide polymorphisms (SNPs) present in the casein complex of 159 unrelated individuals of diverse ancestry, which were organized into 86 haplotypes. The Ali and Schaeffer model was chosen as the best fitting model for milk yield (Kg), protein, fat, dry matter, and lactose (%), while parabolic yield-density was chosen as the best fitting model for somatic cells count (SCC × 103 sc/mL). Peak and persistence for all traits were computed respectively. Statistically significant differences (p < 0.05) were found for milk yield and components. However, no significant difference was found for any curve shape parameter except for protein percentage peak. Those haplotypes for which higher milk yields were reported were the ones that had higher percentages for protein, fat, dry matter, and lactose, while the opposite trend was described by somatic cells counts. Conclusively, casein complex haplotypes can be considered in selection strategies for economically important traits in dairy goats

    Software-automatized individual lactation model fitting, peak and persistence and Bayesian criteria comparison for milk yield genetic studies in Murciano-Granadina goats

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    SPSS model syntax was defined and used to evaluate the individual performance of 49 linear and non-linear models to fit the lactation curve of 159 Murciano-Granadina goats selected for genotyping analyses. Lactation curve shape, peak and persistence were evaluated for each model using 3107 milk yield controls with an average of 3.78 ± 2.05 lactations per goat. Best fit (Adjusted R2) values (0.47) were reached by the five-parameter logarithmic model of Ali and Schaeffer. Three main possibilities were detected: non-fitting (did not converge), standard (Adjusted R2 over 75%) and atypical curves (Adjusted R2 below 75%). All the goats fitted for 38 models. The ability to fit different possible functional forms for each goat, which progressively increased with the number of parameters comprised in each model, translated into a higher sensitivity to explaining curve shape individual variability. However, for models for which all goats fitted, only moderate increases in explanatory and predictive potential (AIC, AICc or BIC) were found. The Ali and Schaeffer model reported the best fitting results to study the genetic variability behind goat milk yield and perhaps enhance the evaluation of curve parameters as trustable future selection criteria to face the future challenges offered by the goat dairy industry

    Pilot3 D1.1 - Technical resources and problem definition

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    This deliverable starts with the proposal of Pilot3 but incorporates the development produced during the first four months of the project: activities on different workpackages, interaction with Topic Manager and Project Officer, and input received during the first Advisory Board meeting. This deliverable presents the definition of Pilot3 concept and methodology. It includes the high level the requirements of the prototype, preliminary data requirements, preliminary indicators that will be considered and a preliminary definition of case studies. The deliverable aims at defining the view of the consortium on the project at these early stages, while highlighting the feedback obtained from the Advisory Board and the further activities required to define some of the aspects of the project

    Observational constraints to boxy/peanut bulge formation time

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    Boxy/peanut bulges are considered to be part of the same stellar structure as bars and both could be linked through the buckling instability. The Milky Way is our closest example. The goal of this letter is determining if the mass assembly of the different components leaves an imprint in their stellar populations allowing to estimate the time of bar formation and its evolution. To this aim we use integral field spectroscopy to derive the stellar age distributions, SADs, along the bar and disc of NGC 6032. The analysis shows clearly different SADs for the different bar areas. There is an underlying old (>=12 Gyr) stellar population for the whole galaxy. The bulge shows star formation happening at all times. The inner bar structure shows stars of ages older than 6 Gyrs with a deficit of younger populations. The outer bar region presents a SAD similar to that of the disc. To interpret our results, we use a generic numerical simulation of a barred galaxy. Thus, we constrain, for the first time, the epoch of bar formation, the buckling instability period and the posterior growth from disc material. We establish that the bar of NGC 6032 is old, formed around 10 Gyr ago while the buckling phase possibly happened around 8 Gyr ago. All these results point towards bars being long-lasting even in the presence of gas.Comment: Accepted for publication in MNRAS Letter
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