We present a search and analysis of variable stars in the recently discovered Crater II dwarf galaxy. Based on B, V, I data collected with the Isaac Newton Telescope (FoV∼0.44 deg2), we detected 37 ...variable stars, of which 34 are bone-fide RR Lyrae stars of Crater II (28 RRab, 4 RRc, 2 RRd). We applied the metal-independent (V, B - V) Period-Wesenheit relation and derived a true distance modulus (μ = 20.30 ± 0.08 mag (σ = 0.16 mag). Individual metallicities for RR Lyrae stars were derived by inversion of the predicted I-band Period-Luminosity relation. We find a mean metallicity of Fe/H = -1.64 and a standard deviation of σ _{Fe/H}=0.21 dex, compatible with either negligible or vanishing intrinsic metallicity dispersion. The analysis of the colour-magnitude diagram reveals a stark paucity of blue horizontal branch stars, at odds with other Galactic dwarfs, and globular clusters with similar metal abundances.
Abstract
We report the detection of three RR Lyrae (RRL) stars (two RRc and one RRab) in the ultra-faint dwarf (UFD) galaxy Centaurus I (Cen I) and two Milky Way (MW)
δ
Scuti/SX Phoenicis stars based ...on multi-epoch
giz
DECam observations. The two RRc stars are located within two times the half-light radius (
r
h
) of Cen I, while the RRab star (CenI-V3) is at ∼6
r
h
. The presence of three distant RRL stars clustered this tightly in space represents a 4.7
σ
excess relative to the smooth distribution of RRL in the Galactic halo. Using the newly detected RRL stars, we obtain a distance modulus to Cen I of
μ
0
= 20.354 ± 0.002 mag (
σ
= 0.03 mag), a heliocentric distance of
D
⊙
= 117.7 ± 0.1 kpc (
σ
= 1.6 kpc), with systematic errors of 0.07 mag and 4 kpc. The location of the Cen I RRL stars in the Bailey diagram is in agreement with other UFD galaxies (mainly Oosterhoff II). Finally, we study the relative rate of RRc+RRd (RRcd) stars (
f
cd
) in UFD and classical dwarf galaxies. The full sample of MW dwarf galaxies gives a mean of
f
cd
= 0.28. While several UFD galaxies, such as Cen I, present higher RRcd ratios, if we combine the RRL populations of all UFD galaxies, the RRcd ratio is similar to the one obtained for the classical dwarfs (
f
cd
∼ 0.3). Therefore, there is no evidence for a different fraction of RRcd stars in UFD and classical dwarf galaxies.
ABSTRACT We report the discovery of an excess of main-sequence turnoff stars in the direction of the constellations of Eridanus and Phoenix from the first-year data of the Dark Energy Survey (DES). ...The Eridanus-Phoenix (EriPhe) overdensity is centered around and and spans at least 30° in longitude and 10° in latitude. The Poisson significance of the detection is at least . The stellar population in the overdense region is similar in brightness and color to that of the nearby globular cluster NGC 1261, indicating that the heliocentric distance of EriPhe is about . The extent of EriPhe in projection is therefore at least ∼4 kpc by ∼3 kpc. On the sky, this overdensity is located between NGC 1261 and a new stellar stream discovered by DES at a similar heliocentric distance, the so-called Phoenix Stream. Given their similar distance and proximity to each other, it is possible that these three structures may be kinematically associated. Alternatively, the EriPhe overdensity is morphologically similar to the Virgo overdensity and the Hercules-Aquila cloud, which also lie at a similar Galactocentric distance. These three overdensities lie along a polar plane separated by ∼120° and may share a common origin. Spectroscopic follow-up observations of the stars in EriPhe are required to fully understand the nature of this overdensity.
We present cosmological results from a combined analysis of galaxy clustering and weak gravitational lensing, using 1321 deg2 of griz imaging data from the first year of the Dark Energy Survey (DES ...Y1). We combine three two-point functions: (i) the cosmic shear correlation function of 26 million source galaxies in four redshift bins, (ii) the galaxy angular autocorrelation function of 650,000 luminous red galaxies in five redshift bins, and (iii) the galaxy-shear cross-correlation of luminous red galaxy positions and source galaxy shears. To demonstrate the robustness of these results, we use independent pairs of galaxy shape, photometric-redshift estimation and validation, and likelihood analysis pipelines. To prevent confirmation bias, the bulk of the analysis was carried out while “blind” to the true results; we describe an extensive suite of systematics checks performed and passed during this blinded phase. The data are modeled in flat ΛCDM and wCDM cosmologies, marginalizing over 20 nuisance parameters, varying 6 (for ΛCDM) or 7 (for wCDM) cosmological parameters including the neutrino mass density and including the 457×457 element analytic covariance matrix. We find consistent cosmological results from these three two-point functions and from their combination obtain S8≡σ8(Ωm/0.3)0.5=0.773−0.020+0.026 and Ωm=0.267−0.017+0.030 for ΛCDM; for wCDM, we find S8=0.782−0.024+0.036, Ωm=0.284−0.030+0.033, and w=−0.82−0.20+0.21 at 68% C.L. The precision of these DES Y1 constraints rivals that from the Planck cosmic microwave background measurements, allowing a comparison of structure in the very early and late Universe on equal terms. Although the DES Y1 best-fit values for S8 and Ωm are lower than the central values from Planck for both ΛCDM and wCDM, the Bayes factor indicates that the DES Y1 and Planck data sets are consistent with each other in the context of ΛCDM. Combining DES Y1 with Planck, baryonic acoustic oscillation measurements from SDSS, 6dF, and BOSS and type Ia supernovae from the Joint Lightcurve Analysis data set, we derive very tight constraints on cosmological parameters: S8=0.802±0.012 and Ωm=0.298±0.007 in ΛCDM and w=−1.00−0.04+0.05 in wCDM. Upcoming Dark Energy Survey analyses will provide more stringent tests of the ΛCDM model and extensions such as a time-varying equation of state of dark energy or modified gravity.
During development inhibitor of DNA-bind-2 (Id2) regulates proliferation and differentiation. Id2 expression has been detected in cancer cells, yet its cellular function and validity as a therapeutic ...target remains largely unknown. Immunohistochemical analysis of colorectal cancer (CRC) specimens revealed that Id2 was undetectable in normal colonic mucosa, but occurs in 40% of primary tumors and in most CRC liver metastases (P<0.0001). Additionally, Id2 was expressed in all CRC cell lines assayed. CRC cells with reduced Id2 expression demonstrated reduced proliferation. Analysis of CRC cell cycle regulatory proteins showed that reducing Id2 levels reduces cyclin D1 levels and increased p21 levels. Reduction of Id2 expression also enhanced tumor cell apoptosis, increasing levels of the pro-apoptotic protein Bim/Bod, and cleavage of caspase-7 and poly (ADP-ribose) polymerase. In vivo studies show tumors derived from cells with decreased Id2 levels formed smaller tumors with fewer metastases compared with tumors with normal levels (P<0.05). Furthermore, intraperitoneal administration of Id2 small interfering RNA (siRNA) conjugated with the neutral liposome 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine decreased tumor burden in mice compared with control treatment (P=0.006). We conclude that Id2 is upregulated in CRC, and is important in promoting cell survival. In vivo targeting of Id2 by siRNA establishes that it is a valid therapeutic target where its expression occurs.
We present the results from a search for the electromagnetic counterpart of the LIGO/Virgo event S190510g using the Dark Energy Camera (DECam). S190510g is a binary neutron star (BNS) merger ...candidate of moderate significance detected at a distance of 227 92 Mpc and localized within an area of 31 (1166) square degrees at 50% (90%) confidence. While this event was later classified as likely nonastrophysical in nature within 30 hours of the event, our short latency search and discovery pipeline identified 11 counterpart candidates, all of which appear consistent with supernovae following offline analysis and spectroscopy by other instruments. Later reprocessing of the images enabled the recovery of six more candidates. Additionally, we implement our candidate selection procedure on simulated kilonovae and supernovae under DECam observing conditions (e.g., seeing and exposure time) with the intent of quantifying our search efficiency and making informed decisions on observing strategy for future similar events. This is the first BNS counterpart search to employ a comprehensive simulation-based efficiency study. We find that using the current follow-up strategy, there would need to be 19 events similar to S190510g for us to have a 99% chance of detecting an optical counterpart, assuming a GW170817-like kilonova. We further conclude that optimization of observing plans, which should include preference for deeper images over multiple color information, could result in up to a factor of 1.5 reduction in the total number of follow-ups needed for discovery.
Objective
To confirm that a single water‐surface sweep‐net collection coupled with three calibration factors (2.6, 3.0 and 3.5 for 1/3, 2/3 and 3/3 water levels, respectively) (WSCF) could accurately ...estimate very low to high Aedes aegypti pupae numbers in water containers more rapidly than the exhaustive 5‐sweep and total count (ESTC) method recommended by WHO.
Methods
Both methods were compared in semi‐field trials using low (n = 25) to moderate (n = 50–100) pupae numbers in a 250‐l drum at 1/3, 2/3 and 3/3 water levels, and by their mean‐time determinations using 200 pupae in three 220‐ to 1024‐l water containers at these water levels. Accuracy was further assessed using 69.1% (393/569) of the field‐based drums and tanks which contained <100 pupae.
Results
The WSCF method accurately estimated total populations in the semi‐field trials up to 13.0 times faster than the ESTC method (all P < 0.001); no significant differences (all P‐values ≥ 0.05) were obtained between the methods for very low (n = 4) to low–moderate (n = 25–100) and high (n > 100) pupae numbers/container and without sediment disturbance.
Conclusion
The simple WSCF method sensitively, accurately and robustly estimated total pupae numbers in their principal breeding sites worldwide, containers with >20 l water volumes, significantly (2.7‐ to 13.0‐fold: all P‐values <0.001) faster than the ESTC method for very low to high pupae numbers/container without contaminating the clean water by sediment disturbance which is generated using the WHO‐recommended ESTC method. The WSCF method seems ideal for global community‐based surveillance and control programmes.
Objectif
Confirmer qu'une collecte unique par balayage de la surface de l'eau à l'aide d'un tamis, couplé à trois facteurs d’étalonnage (WSCF): 2,6; 3,0 et 3,5 pour les niveaux de remplissage d'eau de 1/3, 2/3 et 3/3, respectivement, peut permettre d'estimer avec précision des nombres très faibles à élevés de pupes d’Aedes aegypti dans des récipients d'eau, plus rapidement que la méthode de balayage exhaustif de 5 balayages et de comptage total (ESTC) recommandée par l’OMS.
Méthodes
Les deux méthodes ont été comparées dans des essais semi‐terrain en utilisant un nombre faible (n = 25) à modérée (n = 50 à 100) de pupes dans un tonneau de 250 litres à des niveaux de remplissage d'eau de 1/3, 2/3 et 3/3; et par leurs temps moyens de détermination en utilisant 200 pupes dans trois conteneurs d'eau de 220 à 1024 litres à ces niveaux de remplissage d'eau. La précision a en outre été évaluée en utilisant 69,1% (393/569) des tonneaux et des récipients testés sur le terrain qui contenaient moins de 100 pupes.
Résultats
La méthode WSCF a estimé avec précision les populations totales dans les essais semi‐terrain jusqu’à 13,0 fois plus rapidement que la méthode ESTC (toutes les valeurs p <0,001); aucune différence significative (toutes les valeurs p> 0,05) n'a été observée entre les méthodes pour les nombres très faibles (n = 4) à faiblement modérés (n = 25 à 100) et élevés (n > 100) de pupes par récipient et sans la perturbation des sédiments.
Conclusion
La méthode WSCF simple a permis une estimation sensible, précise et robuste du nombre total de pupes dans leurs principaux sites de reproduction à travers le monde, les conteneurs avec des volumes d'eau > 20 litres, plus rapidement de façon significative (de 2,7 à 13,0 fois: toutes les valeurs p <0,001) que la méthode ESTC pour des nombres très faibles à élevés de pupes par conteneur sans contaminer l'eau potable par la perturbation des sédiments générée avec l'utilisation de la méthode ESTC recommandée par l’OMS. La méthode WSCF semble idéale pour les programmes de surveillance et de lutte communautaires à travers le monde.
Objetivo
Confirmar que una única recolección con red mediante barrido rápido sobre la superficie del agua combinado con tres factores de calibración (2.6, 3.0 y 3.5 para niveles de agua 1/3, 2/3 y 3/3 respectivamente) (BRFC) pueden servir para calcular de forma precisa desde números muy bajos hasta números muy altos de pupas de Aedes aegypti en contenedores de agua, de forma más rápida que el método de barrido exhaustivo y conteo total (BRCT) recomendado por la OMS.
Métodos
Ambos métodos se compararon en ensayos bajo condiciones de semicampo, utilizando números de pupas bajos (n= 25) a moderados (n= 50‐100), en un contenedores de 250‐litros con niveles de agua de 1/3, 2/3 y 3/3; y por las determinaciones de tiempo medio utilizando 200 pupas en tres contenedores de agua de 220‐1024‐litros con los mismos niveles de agua. La precisión se evaluó utilizando un 69.1% (393/569) de los contenedores localizados en el campo y de los tanques que contenían <100 pupas.
Resultados
El método BRFC calculaba de forma precisa la población total en ensayos bajo condiciones de semicampo y con una velocidad de hasta 13.0 veces mayor que el método BRCT (p <0.001); no se obtuvieron diferencias significativas (todos los valores p ≥0.05) entre los métodos para números de pupa/contenedor muy bajos (n= 4) a bajos‐moderados (n= 25‐100) y altos (n>100) y sin perturbación de sedimentos.
Conclusión
El método simple de BRFC calculó de forma sensible, precisa y robusta el número total de pupas en los que son su principal lugar de reproducción a nivel mundial, contenedores con un volumen de agua >20 litros, significativamente más rápido (2.7‐13.0 veces: todos los valores p <0.001) que el método BRCT para números de pupa/contenedor desde muy bajos hasta altos y sin contaminar el agua limpia por perturbación de sedimentos, que se genera utilizando el método BRCT recomendado por la OMS. El método BRFC parece ideal para la vigilancia comunitaria y programas de control a nivel global.
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