The Initial Mass Functions in the Super-Star-Clusters NGC 1569A and NGC 1705-1

I use recent photometric and stellar velocity dispersion measurements of the super-star-clusters (SSCs) NGC 1569A and NGC 1705-1 to determine their present-day luminosity/mass (L_V/M) ratios. I then use the inferred L_V/M ratios, together with population synthesis models of evolving star-clusters, to constrain the initial-mass-functions (IMFs) in these objects. I find that (L_V/M)_solar=28.9 in 1569A, and (L_V/M)_solar=126 in 1705-1. It follows that in 1569A the IMF is steep with alpha~2.5 for m**(-alpha)dm IMFs which extend to 0.1 M_sun. This implies that most of the stellar mass in 1569A is contained in low-mass (< 1 M_sun) stars. However, in 1705-1 the IMF is either flat, with alpha<2$, or it is truncated at a lower mass-limit between 1 and 3 M_sun. I compare the inferred IMFs with the mass functions (MFs) of Galactic globular clusters. It appears that 1569A has a sufficient reservoir of low-mass stars for it to plausibly evolve into an object similar to Galactic globular clusters. However, the apparent deficiency of low-mass stars in 1705-1 may make it difficult for this SSC to become a globular cluster. If low-mass stars do dominate the cluster mass in 1705-1, the large L_V/M ratio in this SSC may be evidence that the most massive stars have formed close to the cluster cores.Comment: ApJ, in press. 19 Pages, Latex; [email protected]

The Ratio of Ortho- to Para-H2 in Photodissociation Regions

We discuss the ratio of ortho- to para-H2 in photodissociation regions (PDRs). We draw attention to an apparent confusion in the literature between the ortho-to-para ratio of molecules in FUV-pumped vibrationally excited states, and the H2 ortho-to-para abundance ratio. These ratios are not the same because the process of FUV-pumping of fluorescent H2 emission in PDRs occurs via optically thick absorption lines. Thus, gas with an equilibrium ratio of ortho- to para-H2 equal to 3 will yield FUV-pumped vibrationally excited ortho-to-para ratios smaller than 3, because the ortho-H2 pumping rates are preferentially reduced by optical depth effects. Indeed, if the ortho and para pumping lines are on the ``square root'' part of the curve-of-growth, then the expected ratio of ortho and para vibrational line strengths is the square root of 3, ~ 1.7, close to the typically observed value. Thus, contrary to what has sometimes been stated in the literature, most previous measurements of the ratio of ortho- to para-H2 in vibrationally excited states are entirely consistent with a total ortho-to-para ratio of 3, the equilibrium value for temperatures greater than 200 K. We present an analysis and several detailed models which illustrate the relationship between the total ratios of ortho- to para-H2 and the vibrationally excited ortho-to-para ratios in PDRs. Recent Infrared Space Observatory (ISO) measurements of pure rotational and vibrational H2 emissions from the PDR in the star-forming region S140 provide strong observational support for our conclusions.Comment: 23 pages (including 5 figures), LaTeX, uses aaspp4.sty, accepted for publication in Ap

Ionizing Photon Emission Rates from O- and Early B-type Stars and Clusters

We present new computations of the ionizing spectral energy distributions (SEDs) and Lyman continuum (Lyc) and HeI continuum photon emission rates, for hot O-type and early B-type stars. We consider solar metallicity stars, with effective temperatures ranging from 25,000 to 55,000 K and surface gravities (cm s^-2) logg ranging from 3 to 4, covering the full range of spectral types and luminosity classes for hot stars. We use our updated (WM-basic) code to construct radiation-driven wind atmosphere models for hot stars. Our models include the coupled effects of hydrodynamics and non-LTE radiative transfer in spherically outflowing winds, including the detailed effects of metal line blocking and line blanketing on the radiative transfer and energy balance. We incorporate our hot-star models into our population synthesis code (STARS), and we compute the time-dependent SEDs and resulting Lyc and HeI emission rates for evolving star clusters. We present results for continuous and impulsive star formation for a range of assumed stellar initial mass functions.Comment: 23 pages, 7 figures. To appear in the Astrophysical Journal. For grid of star models see ftp://wise3.tau.ac.il/pub/star

Age before stage: insulin resistance rises before the onset of puberty: a 9-year longitudinal study (EarlyBird 26).

OBJECTIVE: Insulin resistance (IR) is associated with diabetes. IR is higher during puberty in both sexes, with some studies showing the increase to be independent of changes in adiposity. Few longitudinal studies have reported on children, and it remains unclear when the rise in IR that is often attributed to puberty really begins. We sought to establish from longitudinal data its relationship to pubertal onset, and interactions with age, sex, adiposity, and IGF-1. RESEARCH DESIGN AND METHODS: The EarlyBird Diabetes study is a longitudinal prospective cohort study of healthy children aged 5-14 years. Homeostasis model assessment (HOMA-IR), skinfolds (SSF), adiposity (percent fat, measured by dual-energy X-ray absorptiometry), serum leptin, and IGF-1 were measured annually in 235 children (134 boys). Pubertal onset was adduced from Tanner stage (TS) and from the age at which luteinizing hormone (LH) first became serially detectable (≥0.2 international units/L). RESULTS: IR rose progressively from age 7 years, 3-4 years before TS2 was reached or LH became detectable. Rising adiposity and IGF-1 together explained 34% of the variance in IR in boys and 35% in girls (both P < 0.001) over the 3 years preceding pubertal onset. The contribution of IGF-1 to IR was greater in boys, despite their comparatively lower IGF-1 levels. CONCLUSIONS: IR starts to rise in mid-childhood, some years before puberty. Its emergence relates more to the age of the child than to pubertal onset. More than 60% of the variation in IR prior to puberty was unexplained. The demography of childhood diabetes is changing, and prepubertal IR may be important

The Super Star Cluster NGC 1569-A Resolved on Sub-Parsec Scales with Hubble Space Telescope Spectroscopy

We present 3000--10000 Ang HST/STIS long-slit spectroscopy of the bright super star cluster A (SSC-A) in the dwarf starburst galaxy NGC 1569. The 0.05" HST angular resolution allows, for the first time, to probe for spatial variations in the stellar population of a ~ 10^6 M_sun SSC. Integrated ground-based spectra of SSC-A have previously revealed young Wolf-Rayet (WR) signatures that coexist with features from supposedly older, red supergiant (RSG), populations. We find that the WR emission complexes come solely from the subcluster A2, identified in previous HST imaging, and are absent from the main cluster A1, thus resolving the question of whether the WR and RSG features arise in a single or distinct clusters. The equivalent widths of the WR features in A2 --- including the CIV 5808 complex which we detect in this object for the first time --- are larger than previously observed in other WR galaxies. Models with sub-solar metallicity, as inferred from the nebular emission lines of this galaxy, predict much lower equivalent widths. On the ``clean'' side of A1, opposite to A2, we find no evidence for radial gradients in the observed stellar population at 0.05"<R<0.40" (~0.5 to 5 pc), neither in broad-band, low-resolution, spectra nor in medium-resolution spectra of the infrared CaII triplet.Comment: 5 pages, accepted for publication in ApJ Le

CN and HCN in Dense Interstellar Clouds

We present a theoretical investigation of CN and HCN molecule formation in dense interstellar clouds. We study the gas-phase CN and HCN production efficiencies from the outer photon-dominated regions (PDRs) into the opaque cosmic-ray dominated cores. We calculate the equilibrium densities of CN and HCN, and of the associated species C+, C, and CO, as functions of the far-ultraviolet (FUV) optical depth. We consider isothermal gas at 50 K, with hydrogen particle densities from 10^2 to 10^6 cm^-3. We study clouds that are exposed to FUV fields with intensities 20 to 2*10^5 times the mean interstellar FUV intensity. We assume cosmic-ray H2 ionization rates ranging from 5*10^-17 s^-1, to an enhanced value of 5*10^-16 s^-1. We also examine the sensitivity of the density profiles to the gas-phase sulfur abundance.Comment: Accepted for publication in ApJ, 33 pages, 8 figure

Use of Shotgun Metagenomics and Metabolomics to Evaluate the Impact of Glyphosate or Roundup MON 52276 on the Gut Microbiota and Serum Metabolome of Sprague-Dawley Rats

Background: There is intense debate on whether glyphosate can inhibit the shikimate pathway of gastrointestinal microorganisms, with potential health implications. Objectives: We tested whether glyphosate or its representative EU herbicide formulation Roundup MON 52276 affects the rat gut microbiome. Methods: We combined cecal microbiome shotgun metagenomics with serum and cecum metabolomics to assess the effects of glyphosate [0.5, 50, 175 mg/kg body weight (BW) per day] or MON 52276 at the same glyphosate-equivalent doses, in a 90-d toxicity test in rats. Results: Glyphosate and MON 52276 treatment resulted in ceca accumulation of shikimic acid and 3-dehydroshikimic acid, suggesting inhibition of 5-enolpyruvylshikimate-3-phosphate synthase of the shikimate pathway in the gut microbiome. Cysteinylglycine, γ-glutamylglutamine, and valylglycine levels were elevated in the cecal microbiome following glyphosate and MON 52276 treatments. Altered cecum metabolites were not differentially expressed in serum, suggesting that the glyphosate and MON 52276 impact on gut microbial metabolism had limited consequences on physiological biochemistry. Serum metabolites differentially expressed with glyphosate treatment were associated with nicotinamide, branched-chain amino acid, methionine, cysteine, and taurine metabolism, indicative of a response to oxidative stress. MON 52276 had similar, but more pronounced, effects than glyphosate on the serum metabolome. Shotgun metagenomics of the cecum showed that treatment with glyphosate and MON 52276 resulted in higher levels of Eggerthella spp., Shinella zoogleoides, Acinetobacter johnsonii, and Akkermansia muciniphila. Shinella zoogleoides was higher only with MON 52276 exposure. In vitro culture assays with Lacticaseibacillus rhamnosus strains showed that Roundup GT plus inhibited growth at concentrations at which MON 52276 and glyphosate had no effect. Discussion: Our study highlights the power of multi-omics approaches to investigate the toxic effects of pesticides. Multi-omics revealed that glyphosate and MON 52276 inhibited the shikimate pathway in the rat gut microbiome. Our findings could be used to develop biomarkers for epidemiological studies aimed at evaluating the effects of glyphosate herbicides on humans

Insulin pump therapy with automated insulin suspension in response to hypoglycemia: reduction in nocturnal hypoglycemia in those at greatest risk.

OBJECTIVE: To evaluate a sensor-augmented insulin pump with a low glucose suspend (LGS) feature that automatically suspends basal insulin delivery for up to 2 h in response to sensor-detected hypoglycemia. RESEARCH DESIGN AND METHODS: The LGS feature of the Paradigm Veo insulin pump (Medtronic, Inc., Northridge, CA) was tested for 3 weeks in 31 adults with type 1 diabetes. RESULTS: There were 166 episodes of LGS: 66% of daytime LGS episodes were terminated within 10 min, and 20 episodes lasted the maximum 2 h. LGS use was associated with reduced nocturnal duration ≤2.2 mmol/L in those in the highest quartile of nocturnal hypoglycemia at baseline (median 46.2 vs. 1.8 min/day, P = 0.02 [LGS-OFF vs. LGS-ON]). Median sensor glucose was 3.9 mmol/L after 2-h LGS and 8.2 mmol/L at 2 h after basal restart. CONCLUSIONS: Use of an insulin pump with LGS was associated with reduced nocturnal hypoglycemia in those at greatest risk and was well accepted by patients

Comparing Entrustment Decision-Making Outcomes of the Core Entrustable Professional Activities Pilot, 2019-2020

IMPORTANCE: Gaps in readiness for indirect supervision have been identified for essential responsibilities encountered early in residency, presenting risks to patient safety. Core Entrustable Professional Activities (EPAs) for entering residency have been proposed as a framework to address these gaps and strengthen the transition from medical school to residency. OBJECTIVE: To assess progress in developing an entrustment process in the Core EPAs framework. DESIGN, SETTING, AND PARTICIPANTS: In this quality improvement study in the Core EPAs for Entering Residency Pilot, trained faculty made theoretical entrustment determinations and recorded the number of workplace-based assessments (WBAs) available for each determination in 2019 and 2020. Four participating schools attempted entrustment decision-making for all graduating students or a randomly selected subset of students. Deidentified, individual-level data were merged into a multischool database. INTERVENTIONS: Schools implemented EPA-related curriculum, WBAs, and faculty development; developed systems to compile and display data; and convened groups to make theoretical summative entrustment determinations. MAIN OUTCOMES AND MEASURES: On an EPA-specific basis, the percentage of students for whom an entrustment determination could be made, the percentage of students ready for indirect supervision, and the volume of WBAs available were recorded. RESULTS: Four participating schools made 4525 EPA-specific readiness determinations (2296 determinations in 2019 and 2229 determinations in 2020) for 732 graduating students (349 students in 2019 and 383 students in 2020). Across all EPAs, the proportion of determinations of ready for indirect supervision increased from 2019 to 2020 (997 determinations [43.4%] vs 1340 determinations [60.1%]; 16.7 percentage point increase; 95% CI, 13.8-19.6 percentage points; P \u3c .001), as did the proportion of determinations for which there were 4 or more WBAs (456 of 2295 determinations with WBA data [19.9%] vs 938 [42.1%]; 22.2 percentage point increase; 95% CI, 19.6-24.8 percentage points; P \u3c .001). The proportion of EPA-specific data sets considered for which an entrustment determination could be made increased from 1731 determinations (75.4%) in 2019 to 2010 determinations (90.2%) in 2020 (14.8 percentage point increase; 95% CI, 12.6-16.9 percentage points; P \u3c .001). On an EPA-specific basis, there were 5 EPAs (EPA 4 [orders], EPA 8 [handovers], EPA 10 [urgent care], EPA 11 [informed consent], and EPA 13 [patient safety]) for which few students were deemed ready for indirect supervision and for which there were few WBAs available per student in either year. For example, for EPA 13, 0 of 125 students were deemed ready in 2019 and 0 of 127 students were deemed ready in 2020, while 0 determinations in either year included 4 or more WBAs. CONCLUSIONS AND RELEVANCE: These findings suggest that there was progress in WBA data collected, the extent to which entrustment determinations could be made, and proportions of entrustment determinations reported as ready for indirect supervision. However, important gaps remained, particularly for a subset of Core EPAs

Exploring the determinants of ethnic differences in insulin clearance between men of Black African and White European ethnicity

Aim: People of Black African ancestry, who are known to be at disproportionately high risk of type 2 diabetes (T2D), typically exhibit lower hepatic insulin clearance compared with White Europeans. However, the mechanisms underlying this metabolic characteristic are poorly understood. We explored whether low insulin clearance in Black African (BA) men could be explained by insulin resistance, subclinical inflammation or adiponectin concentrations. Methods: BA and White European (WE) men, categorised as either normal glucose tolerant (NGT) or with T2D, were recruited to undergo the following: a mixed meal tolerance test with C-peptide modelling to determine endogenous insulin clearance; fasting serum adiponectin and cytokine profiles; a hyperinsulinaemic–euglycaemic clamp to measure whole-body insulin sensitivity; and magnetic resonance imaging to quantify visceral adipose tissue. Results: Forty BA (20 NGT and 20 T2D) and 41 WE (23 NGT and 18 T2D) men were studied. BA men had significantly lower insulin clearance (P = 0.011) and lower plasma adiponectin (P = 0.031) compared with WE men. In multiple regression analysis, ethnicity, insulin sensitivity and plasma adiponectin were independent predictors of insulin clearance, while age, visceral adiposity and tumour necrosis factor alpha (TNF-α) did not significantly contribute to the variation. Conclusion: These data suggest that adiponectin may play a direct role in the upregulation of insulin clearance beyond its insulin-sensitising properties