Abstract
We present a study of the effective (half-light) radii and other structural properties of a systematically selected sample of young, massive star clusters (≥5 × 10
3
and ≤200 Myr) in two ...nearby spiral galaxies, NGC 628 and NGC 1313. We use
Hubble Space Telescope
(
HST
) WFC3/UVIS and archival ACS/WFC data obtained by the Legacy Extragalactic UV Survey (LEGUS), an
HST
Treasury Program. We measure effective radii with GALFIT, a two-dimensional image-fitting package, and with a new technique to estimate effective radii from the concentration index of observed clusters. The distribution of effective radii from both techniques spans ∼0.5–10 pc and peaks at 2–3 pc for both galaxies. We find slight positive correlations between effective radius and cluster age in both galaxies, but no significant relationship between effective radius and galactocentric distance. Clusters in NGC 1313 display a mild increase in effective radius with cluster mass, but the trend disappears when the sample is divided into age bins. We show that the vast majority of the clusters in both galaxies are much older than their dynamical times, suggesting they are gravitationally bound objects. We find that about half of the clusters in NGC 628 are underfilling their Roche lobes, based on their Jacobi radii. Our results suggest that the young, massive clusters in NGC 628 and NGC 1313 are expanding, due to stellar mass loss or two-body relaxation, and are not significantly influenced by the tidal fields of their host galaxies.
Anemia remains a pervasive public health problem among preschool-age children in Ghana. Recent analyses have found that anemia in Ghanaian children, particularly in Southern regions, is largely ...attributable to infectious causes, rather than nutritional factors. Infections with enteropathogens can reduce iron absorption and increase systemic inflammation, but few studies have examined direct links between enteropathogens and anemia. This study investigated associations between detection of individual bacterial enteropathogens and systemic inflammation, iron deficiency, and anemia among 6- to 59-month-old children in Greater Accra, Ghana. Serum samples were analyzed from a cross-sectional sample of 262 children for concentrations of hemoglobin (Hb), biomarkers of systemic inflammation C-reactive protein (CRP) and α-1-acid glycoprotein (AGP), and biomarkers of iron status serum ferritin (SF) and serum transferrin receptor (sTfR). Stool samples were analyzed for ten bacterial enteropathogens using qPCR. We estimated associations between presence of each enteropathogen and elevated systemic inflammation (CRP > 5 mg/L and AGP > 1 g/L), iron deficiency (SF < 12 μg/L and sTfR > 8.3 mg/L) and anemia (Hb < 110 g/L). Enteropathogens were detected in 87% of children's stool despite a low prevalence of diarrhea (6.5%). Almost half (46%) of children had anemia while one-quarter (24%) had iron deficiency (low SF). Despite finding no associations with illness symptoms, Campylobacter jejuni/coli detection was strongly associated with elevated CRP Odds Ratio (95% CI): 3.49 (1.45, 8.41) and elevated AGP 4.27 (1.85, 9.84). Of the pathogens examined, only enteroinvasive Escherichia coli/Shigella spp. (EIEC/Shigella) was associated with iron deficiency, and enteroaggregative Escherichia coli (EAEC) 1.69 (1.01, 2.84) and EIEC/Shigella 2.34 (1.15, 4.76) were associated with anemia. These results suggest that certain enteroinvasive pathogenic bacteria may contribute to child anemia. Reducing exposure to enteropathogens through improved water, sanitation, and hygiene practices may help reduce the burden of anemia in young Ghanaian children.
We present an analysis of the positions and ages of young star clusters in eight local galaxies to investigate the connection between the age difference and separation of cluster pairs. We find that ...star clusters do not form uniformly but instead are distributed so that the age difference increases with the cluster pair separation to the 0.25-0.6 power, and that the maximum size over which star formation is physically correlated ranges from ∼200 pc to ∼1 kpc. The observed trends between age difference and separation suggest that cluster formation is hierarchical both in space and time: clusters that are close to each other are more similar in age than clusters born further apart. The temporal correlations between stellar aggregates have slopes that are consistent with predictions of turbulence acting as the primary driver of star formation. The velocity associated with the maximum size is proportional to the galaxy's shear, suggesting that the galactic environment influences the maximum size of the star-forming structures.
Abstract
We report the large effort that is producing comprehensive high-level young star cluster (YSC) catalogs for a significant fraction of galaxies observed with the Legacy ExtraGalactic UV ...Survey (LEGUS)
Hubble
treasury program. We present the methodology developed to extract cluster positions, verify their genuine nature, produce multiband photometry (from NUV to NIR), and derive their physical properties via spectral energy distribution fitting analyses. We use the nearby spiral galaxy NGC 628 as a test case for demonstrating the impact that LEGUS will have on our understanding of the formation and evolution of YSCs and compact stellar associations within their host galaxy. Our analysis of the cluster luminosity function from the UV to the NIR finds a steepening at the bright end and at all wavelengths suggesting a dearth of luminous clusters. The cluster mass function of NGC 628 is consistent with a power-law distribution of slopes
and a truncation of a few times 10
5
. After their formation, YSCs and compact associations follow different evolutionary paths. YSCs survive for a longer time frame, confirming their being potentially bound systems. Associations disappear on timescales comparable to hierarchically organized star-forming regions, suggesting that they are expanding systems. We find mass-independent cluster disruption in the inner region of NGC 628, while in the outer part of the galaxy there is little or no disruption. We observe faster disruption rates for low mass (≤10
4
) clusters, suggesting that a mass-dependent component is necessary to fully describe the YSC disruption process in NGC 628.
Aims. V838 Monocerotis erupted in 2002, brightened in a series of outbursts, and eventually developed a spectacular light echo. A very red star emerged a few months after the outburst. The whole ...event has been interpreted as the result of a merger. Methods. We obtained near- and mid-IR interferometric observations of V838 Mon with the AMBER and MIDI recombiners located at the Very Large Telescope Interferometer (VLTI) array. The MIDI two-beam observations were obtained with the 8 m unit telescopes between October 2011 and February 2012. The AMBER three-beam observations were obtained with the compact array (B ≤ 35 m) in April 2013 and the long array (B ≤ 140 m) in May 2014, using the 1.8 m auxiliary telescopes. Results. A significant new result is the detection of a compact structure around V838 Mon, as seen from MIDI data. The extension of the structure increases from a FWHM of 25 mas at 8 μm to 70 mas at 13 μm. At the adopted distance of D = 6.1 ± 0.6 kpc, the dust is distributed from about 150 to 400 AU around V838 Mon. The MIDI visibilities reveal a flattened structure whose aspect ratio increases with wavelength. The major axis is roughly oriented around a position angle of − 10°, which aligns with previous polarimetric studies reported in the literature. This flattening can be interpreted as a relic of the 2002 eruption or as caused by the influence of the currently embedded B3V companion. The AMBER data provide a new diameter for the pseudo-photosphere, which shows that its diameter has decreased by about 40% in 10 yr, reaching a radius R∗ = 750 ± 200 R⊙ (3.5 ± 1.0 AU). Conclusions. After the 2002 eruption, which was interpreted as the merging of two stars, it seems that the resulting source is relaxing to a normal state. The nearby environment exhibits an equatorial overdensity of dust up to several hundred AU.
ABSTRACT The Legacy ExtraGalactic UV Survey (LEGUS) is a Cycle 21 Treasury program on the Hubble Space Telescope aimed at the investigation of star formation and its relation with galactic ...environment in nearby galaxies, from the scales of individual stars to those of ∼kiloparsec-size clustered structures. Five-band imaging from the near-ultraviolet to the I band with the Wide-Field Camera 3 (WFC3), plus parallel optical imaging with the Advanced Camera for Surveys (ACS), is being collected for selected pointings of 50 galaxies within the local 12 Mpc. The filters used for the observations with the WFC3 are F275W(λ2704 ), F336W(λ3355 ), F438W(λ4325 ), F555W(λ5308 ), and F814W(λ8024 ); the parallel observations with the ACS use the filters F435W(λ4328 ), F606W(λ5921 ), and F814W(λ8057 ). The multiband images are yielding accurate recent ( 50 Myr) star formation histories from resolved massive stars and the extinction-corrected ages and masses of star clusters and associations. The extensive inventories of massive stars and clustered systems will be used to investigate the spatial and temporal evolution of star formation within galaxies. This will, in turn, inform theories of galaxy evolution and improve the understanding of the physical underpinning of the gas-star formation relation and the nature of star formation at high redshift. This paper describes the survey, its goals and observational strategy, and the initial scientific results. Because LEGUS will provide a reference survey and a foundation for future observations with the James Webb Space Telescope and with ALMA, a large number of data products are planned for delivery to the community.
Shrimp farming constitutes an important source of revenue and employment in many developing countries. However, the shrimp industry has always been plagued with infectious diseases having varied ...aetiologies. Dominated by non - specific immune mechanism, preventive health care strategy is the most appropriate approach to protect the crop. The present study evaluated the efficacy of an actinomycete, Nocardiopsis alba MCCB 110 in eliciting non - specific immune mechanism in Penaeus monodon having Vibrio harveyi as the challenge organism. Haemocyte count, total protein, phenoloxidase, reactive oxygen intermediates, acid and alkaline phosphatase as well as the gene expression of proPO, peroxinectin, transglutaminase, alpha 2-macroglobulin, astakine, crustin, and penaeidin-3 were evaluated. The results demonstrated that the phenoloxidase, respiratory burst, total protein, acid and alkaline phosphatases were higher in the haemolymph of shrimps fed with Nocardiopsis alba MCCB 110 incorporated feed before and after challenge with Vibrio harveyi, compared to those of placebo fed animals. Up-regulation of six immune genes (alpha 2 macroglobulin, penaeidin −3, transglutaminase, proPO, crustin and peroxinectin) during the post-challenge were recorded. Survival of shrimp among the Nocardiopsis alba administered ones was 83% while it was 50% in placebo fed group. The elevated levels of nonspecific immune gene transcripts and concurrent increase in non specific immunity besides the higher survival rate in the Nocardiopsis alba administered group demonstrated the immunomodulatory property of the marine actinomycete Nocardiopsis alba MCCB 110 in the tiger shrimp Penaeus monodon, and on administering it through diet shrimp could be protected from vibriosis especially of V. harveyi.
•A marine actinomycete Nocardiopsis alba MCCB 110 administered through diet enhanced innate immune responses such as phenol oxidase, respiratory burst, total protein, acid and alkaline phosphatases in the tiger shrimp Penaeus monodon.•Nocardiopsis alba supplementation up-regulated the gene expression of alpha 2 macroglobulin, penaeidin −3, transglutaminase, proPO, crustin and peroxinectin.•The survival of shrimp among Nocardiopsis alba administered ones was 83% while it was 50% in control during the post-challenge period with Vibrio harveyi.•This work demonstrated the immunomodulatory property of marine actinomycete Nocardiopsis alba MCCB 110 in the tiger shrimp Penaeus monodon..
Abstract
The Legacy ExtraGalactic UV Survey (LEGUS) is a multiwavelength Cycle 21 Treasury program on the
Hubble Space Telescope
. It studied 50 nearby star-forming galaxies in 5 bands from the ...near-UV to the I-band, combining new Wide Field Camera 3 observations with archival Advanced Camera for Surveys data. LEGUS was designed to investigate how star formation occurs and develops on both small and large scales, and how it relates to the galactic environments. In this paper we present the photometric catalogs for all the apparently single stars identified in the 50 LEGUS galaxies. Photometric catalogs and mosaicked images for all filters are available for download. We present optical and near-UV color–magnitude diagrams for all the galaxies. For each galaxy we derived the distance from the tip of the red giant branch. We then used the NUV color–magnitude diagrams to identify stars more massive than 14
M
⊙
, and compared their number with the number of massive stars expected from the
GALEX
FUV luminosity. Our analysis shows that the fraction of massive stars forming in star clusters and stellar associations is about constant with the star formation rate. This lack of a relation suggests that the timescale for evaporation of unbound structures is comparable or longer than 10 Myr. At low star formation rates this translates to an excess of mass in clustered environments as compared to model predictions of cluster evolution, suggesting that a significant fraction of stars form in unbound systems.
White spot syndrome virus (WSSV), the most contagious pathogen of cultured shrimp, causes mass mortality, leading to huge economic loss to the shrimp industry. The lack of effective therapeutic or ...prophylactic measures has aggravated the situation, necessitating the development of antiviral agents. With this objective, the antiviral activity in the aqueous extract of a mangrove plant
Ceriops tagal
in
Penaeus monodon
was evaluated
.
The
Ceriops tagal
aqueous extract (CTAE) was non-toxic to shrimps at 50 mg/ml when injected intramuscularly at a dosage of 10 μL/animal (0.5 mg/animal) and showed a protective effect against WSSV at 30 mg/ml when mixed with WSSV suspension at a 1:1 ratio. When the extract was administered along with the diet and the animals were challenged orally, there was a dose-dependent increase in survival, culminating in 100 % survival at a concentration of 500 mg/kg body weight/day. Neither hypertrophied nuclei nor the viral envelope protein VP28 could be demonstrated in surviving shrimps using histology and indirect immunofluorescence histochemistry (IIFH), respectively. To elucidate the mode of action, the temporal expression of WSSV genes and shrimp immune genes, including antimicrobial peptides, was attempted. None of the viral genes were found to be expressed in shrimps that were fed with the extract and challenged or in those that were administered CTAE-exposed WSSV. The overall results suggest that the aqueous extract from
C. tagal
can protect
P. monodon
from white spot syndrome virus infection.
Ramos and Gonzalez-Rodriguez introduce the concept of calibration in order to determine whether a system of evidence presentation is a reliable assessor of evidential weight. In this paper, we apply ...this calibration method to a dataset of mixed forensic DNA profiles generated using the QIAGEN Investigator® 24plex QS Kit and interpreted using the probabilistic genotyping software STRmix™.We describe the methodology for applying calibration to sets of forensic DNA profiles. We observe an approximate correspondence of the posterior probability, as assigned from the LR and the prior odds, with the observed rate of true donors for this dataset.
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