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Although prenatal exposure to high ambient temperatures were reported to be associated with preterm birth, limited research assessed the impact of weather-related extreme heat events (EHE) on birthweight, particularly by trimester. We, therefore, investigated the impact of prenatal EHE on birthweight among term babies (tLBW) by trimester and birthweight percentile. We conducted a population-based case–control study on singleton live births at 38–42 gestational weeks in New York State (NYS) by linking weather data with NYS birth certificates. A total of 22,615 cases were identified as birthweight <2500 gram, and a random sample of 139,168 normal birthweight controls was included. EHE was defined as three consecutive days with the maximum temperatures of ≥32.2 °C/90 °F (EHE90) and two consecutive days of temperatures ≥97th percentile (EHE97) based on the distribution of the maximum temperature for the season and region. We estimated odds ratios (ORs) and 95% confidence intervals (95% CI) with multivariable unconditional logistic regression, controlling for confounders. Overall exposure to EHE97 for 2 d was associated with tLBW (OR 1.05; 95% CI 1.02, 1.09); however, the strongest associations were only observed in the first trimester for both heat indicators, especially when exposure was ≥3 d (ORs ranged: 1.06–1.13). EHE in the first trimester was associated with significant reduction in mean birthweight from 26.78 gram (EHE90) to 36.25 gram (EHE97), which mainly affected the 40th and 60th birthweight percentiles. Findings revealed associations between multiple heat indicators and tLBW, where the impact was consistently strongest in the first trimester.
Palaeoscolecid worms are widespread in the Palaeozoic period, and are of key importance to understanding the emergence of moulting animals (superphylum Ecdysozoa). However, palaeoscolecids lack a diagnostic set of morphological characters, and as such are unlikely to form a natural (monophyletic) group. Consequently, detailed anatomical study of individual taxa is necessary in order to evaluate the phylogenetic significance of palaeoscolecids. New specimens of Mafangscolex from the Cambrian Stage 3 Xiaoshiba Lagerstätte in Kunming, China, provide the first detailed account of a proboscis in Palaeoscoelcida sensu stricto, a core group of palaeoscolecids characterized by having a tessellating scleritome of phosphatic plates and platelets. The eversible mouthparts of Mafangscolex comprise an armoured, hexaradially symmetrical introvert, a ring of coronal spines and quincuncially arranged pharyngeal armature, with a range of tooth morphologies. Taken together, this configuration strikingly resembles the proboscis arrangement inferred for the ancestral ecdysozoan. The six-fold symmetry represents an important difference from the pentaradial priapulan proboscis. The retention of key aspects of the ancestral ecdysozoan body plan suggests that palaeoscolecids represent a useful window on the earliest stages of ecdysozoan evolution.
We use the results of a supernova light-curve population synthesis to predict the range of possible supernova light curves arising from a population of single-star progenitors that lead to type IIP supernovae. We calculate multiple models varying the initial mass, explosion energy, nickel mass and nickel mixing and then compare these to type IIP supernovae with detailed light curve data and pre-explosion imaging progenitor constraints. Where a good fit is obtained to observations, we are able to achieve initial progenitor and nickel mass estimates from the supernova lightcurve that are comparable in precision to those obtained from progenitor imaging. For 2 of the 11 IIP supernovae considered our fits are poor, indicating that more progenitor models should be included in our synthesis or that our assumptions, regarding factors such as stellar mass loss rates or the rapid final stages of stellar evolution, may need to be revisited in certain cases. Using the results of our analysis we are able to show that most of the type IIP supernovae have an explosion energy of the order of log(Eexp/ergs) = 50.52 ± 0.10 and that both the amount of nickel in the supernovae and the amount of mixing may have a dependence on initial progenitor mass.
We present results of a supernova lightcurve population synthesis, predicting the range of possible supernova lightcurves arising from a population of progenitor stars that include interacting binary systems. We show that the known diversity of supernova lightcurves can be interpreted as arising from binary interactions. Given detailed models of the progenitor stars, we are able to the determine what parameters within these stars determine the shape of their supernova lightcurve. The primary factors are the mass of supernova ejecta and the mass of hydrogen in the final progenitor. We find that there is a continuum of lightcurve behaviour from type IIP, IIL, to IIb supernovae related to the range of hydrogen and ejecta masses. Most type IIb supernovae arise from a relatively narrow range of initial masses from 10 to 15 M⊙. We also find a few distinct lightcurves that are the result of stellar mergers.
This paper presents a comprehensive investigation into flow past a circular cylinder where compressibility and rarefaction effects play an important role. The study focuses on steady subsonic flow in the Reynolds-number range 0.1–45. Rarefaction, or non-equilibrium, effects in the slip and early transition regime are accounted for using the method of moments and results are compared to data from kinetic theory obtained from the direct simulation Monte Carlo method. Solutions obtained for incompressible continuum flow serve as a baseline to examine non-equilibrium effects on the flow features. For creeping flow, where the Reynolds number is less than unity, the drag coefficient predicted by the moment equations is in good agreement with kinetic theory for Knudsen numbers less than one. When flow separation occurs, we show that the effects of rarefaction and velocity slip delay flow separation and will reduce the size of the vortices downstream of the cylinder. When the Knudsen number is above 0.028, the vortex length shows an initial increase with the Reynolds number, as observed in the standard no-slip continuum regime. However, once the Reynolds number exceeds a critical value, the size of the downstream vortices decreases with increasing Reynolds number until they disappear. An existence criterion, which identifies the limits for the presence of the vortices, is proposed. The flow physics around the cylinder is further analysed in terms of velocity slip, pressure and skin friction coefficients, which highlights that viscous, rarefaction and compressibility effects all play a complex role. We also show that the local Knudsen number, which indicates the state of the gas around the cylinder, can differ significantly from its free-stream value and it is essential that computational studies of subsonic gas flows in the slip and early transition regime are able to account for these strong non-equilibrium effects.
High-energy electron radiography (HEER) has been proposed for time-resolved imaging of materials, high-energy density matter, and for inertial confinement fusion. The areal-density resolution, determined by the image intensity information is critical for these types of diagnostics. Preliminary experimental studies for different materials with the same thickness and the same areal-density target have been imaged and analyzed. Although there are some discrepancies between experimental and theory analysis, the results show that the density distribution can indeed be attained from HEER. The reason for the discrepancies has been investigated and indicates the importance of the uniformity in the transverse distribution beam illuminating the target. Furthermore, the method for generating a uniform transverse distribution beam using octupole magnets was studied and verified by simulations. The simulations also confirm that the octupole field does not affect the angle-position correlation in the center part beam, a critical requirement for the imaging lens. A more practical method for HEER using collimators and octupoles for generating more uniform beams is also described. Detailed experimental results and simulation studies are presented in this paper.
Considering as many as 70% of massive stars interact with a binary companion (Sana et al.2012, 2014), we created a new model of the optical nebular emission of HII regions by combining the results of the Binary Population and Spectral Synthesis (BPASS, Eldridge, Stanway et al.2017) code with the photoionization code (CLOUDY). This is discussed more in detail in Xiao et al.2018a. Then we use this model to explore a variety of emission-line diagnostics of CCSN host HII regions from the PMAS/PPAK Integral-field Supernova hosts COmpilation (PISCO, Galbany et al.2018). We determine the age, metallicity and gas parameters for H II regions associated with CCSNe, contrasting the above variables to distribution type II and type Ibc SNe. We find their nebular emission and CCSN progenitor types are largely determined by past and ongoing binary interactions, for example mass loss, mass gain and stellar mergers. However we note these two types SNe have little preference in their host environment metallicity measured by oxygen abundance or in progenitor initial mass, except that at lower metallicities supernovae are more likely to be of type II. The BPASS and nebular emission models are available from bpass.auckland.ac.nz and warwick.ac.uk/bpass.
It was reported that high blood cholesterol levels increased the susceptibility to mitochondrial dysfunction. This study hypothesized that the gestational hypercholesterolemia (HC) could induce the mitochondrial dysfunction in term human placenta. The eligible pregnant women were recruited from Xuanwu Hospital in Beijing during their first prenatal visit (before their 10th week of pregnancy). In total, 19 pregnant women whose serum total cholesterol levels were higher than 7.25 mm at third trimester (measured at 36–38 weeks) were selected as gestational HC. Other 19 pregnant women with normal cholesterol level matched with age, pre-gestational body mass index, and the neonatal gender were included as the control group. Full-term placenta samples were collected. The mitochondrial DNA (mtDNA) copy number, messenger RNA (mRNA) expression of cytochrome c oxidase subunit I, adenosine triphosphate monophosphatase 6 (ATP6ase), citrate synthase, peroxisome proliferator-activated receptor-γ (PPARγ) co-activator 1α, PPARγ co-activator 1β and estrogen-related receptor-α, and the activity of mitochondrial respiratory chain enzyme complex were measured. Pregnancy outcomes were obtained by extraction from medical records and the labor ward register. The results showed that only placental mtDNA copy number and mRNA expression of ATP6ase were significantly decreased in HC group. No significant differences were detected of other measurements between the two groups. These findings indicated that gestational HC might not induce the damage of placental function seriously.
This paper reports the measurement of the energy loss of protons at the energy of 100 keV penetrating a partially ionized hydrogen plasma. The plasma of ne ≈ 1015–16 cm−3; Te ≈ 1–2 eV and lifetime of about 8 µs is created by the hydrogen gas discharge. The experimental results show an increase of a factor of 2.8 in the energy loss, which are in good agreement with the Bethe, Standard Stopping Model, Li–Petrasso and Vlasov models’ predictions within the error limit. The Bethe–Bloch Coulomb logarithm term is found to increase by a factor of 4.0 for free electrons as compared with the situation where bound electrons prevail. The potential application of protons energy loss for diagnosing the electron density in plasma is proposed too.
The influence of different inclusion levels of a biologically active peptide derived from soybeans by enzymatic hydrolysis, on growth performance, foot pad lesions and carcass characteristics in broilers were examined in this study. Starter (1 to 21 d) and finisher (22 to 42 d) diets, based on maize and soybean meal, were subjected to seven inclusion levels of a commercial soybean bioactive peptide (SBP) product (Fortide, Chengdu Mytech Biotech Co. Ltd., Chengdu, Sichuan, China) at 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 g/kg of diet. All diets were equivalent in respect of energy density, digestible amino acids and other nutrients. A total of 840, one-day-old male broilers (Ross 308) were allocated to 42 pens (20 birds/pen), which were randomly assigned to seven dietary treatments. During the starter period, there was no significant effect of SBP on weight gain and feed intake of the birds. However, a significant (P < 0.05) effect of SBP was observed for the feed conversion ratio (FCR), with SBP inclusion at 3.0 g/kg and above showing lower (P < 0.05) FCR values compared to the diet with no SBP. No effect of SBP was observed for weight gain and feed intake over the whole trial period. However, SBP inclusion tended (P = 0.06) to influence the FCR of birds. Increasing SBP inclusion level resulted in gradual decrease in FCR values, with SBP inclusion at 5.0 and 6.0 g/kg showing lower FCR values compared to the diet with no SBP. Overall, the present study suggests that dietary supplementation of SBP in broiler diets has the potential to improve FCR and to be used as a novel functional protein in poultry diets.
The Binary Population and Spectral Synthesis suite of binary stellar evolution models and synthetic stellar populations provides a framework for the physically motivated analysis of both the integrated light from distant stellar populations and the detailed properties of those nearby. We present a new version 2.1 data release of these models, detailing the methodology by which Binary Population and Spectral Synthesis incorporates binary mass transfer and its effect on stellar evolution pathways, as well as the construction of simple stellar populations. We demonstrate key tests of the latest Binary Population and Spectral Synthesis model suite demonstrating its ability to reproduce the colours and derived properties of resolved stellar populations, including well-constrained eclipsing binaries. We consider observational constraints on the ratio of massive star types and the distribution of stellar remnant masses. We describe the identification of supernova progenitors in our models, and demonstrate a good agreement to the properties of observed progenitors. We also test our models against photometric and spectroscopic observations of unresolved stellar populations, both in the local and distant Universe, finding that binary models provide a self-consistent explanation for observed galaxy properties across a broad redshift range. Finally, we carefully describe the limitations of our models, and areas where we expect to see significant improvement in future versions.
Here a compact three orthogonal planes high-energy electron radiography system was proposed. One of the critical technologies, the ultra-fast beam bunches split from the bunch train are studied. The separated bunches could be transported to the three orthogonal planes of the target for dynamic radiography diagnostics. The key elements of the ultra-fast bunches split system are transverse deflecting cavity (TDC) and the twin septum magnet (TSM). The principle of TDC and TSM are briefly introduced. An example of the beam bunches split system for test experiment (40 MeV electron beam) with TDC and TSM is designed and studied by particle-tracking simulation and it confirms this method is valid and feasible. Especially with TSM, a compact three orthogonal planes radiography system can be realized. The evolution of the beam parameters along the beam line from simulation are investigated. The detailed design of the beam split system and beam dynamics simulation study are presented in this paper.
A biologically active peptide derived from soybeans by enzymatic hydrolysis was evaluated for its potential benefits on chicken growth performance, apparent ileal nutrient digestibility and intestinal histology in young broilers. Seven broiler starter diets, based on maize and soybean meal, were formulated to contain 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 g/kg of a commercial soybean bioactive peptide (SBP) product (Fortide, Chengdu Mytech Biotech Co. Ltd., Chengdu, Sichuan, China). All diets were equivalent in respect of energy density, and digestible protein, amino acids, and other nutrients. A total of 336, one-day-old male broilers (Ross 308) were allocated to 42 cages (eight birds/cage), which were randomly assigned to the six dietary treatments. There was no significant effect of SBP on weight gain and feed intake of the birds. A significant (P < 0.01) effect of SBP was observed for FCR. Inclusion of 1.0, 2.0, 3.0 and 4.0 g SBP/kg of feed resulted in similar FCR values to the diet with no SBP, addition of SBP to the diets at 5.0 and 6.0 g/kg of feed resulted in lower (P < 0.05) FCR compared to the diet with no SBP. Inclusion of SBP had no effect (P > 0.05) on apparent ileal digestibility of nutrients and energy utilisation. Though not statistically significant, SBP inclusion, regardless of level, resulted in 5.7% and 6.3% increases in digestibility of dry matter and nitrogen, respectively. Birds receiving no SBP had the shortest villi and those fed SBP at 3.0 and 6.0 g/kg of feed tended (P = 0.075) to have the greatest villus height. The current findings suggested that including SBP in broiler diets may benefit production through improving feed efficiency, and, to some extent, nutrient digestion and intestinal histology parameters.
Cygnus OB2 is a rich and relatively close (d~1.4 kpc) OB association in our Galaxy. It represents an ideal testbed for our theories about self-enrichment processes produced by pollution of the interstellar medium by successive generations of massive stars. Comerón & Pasquali (2012, A&A, 543, A101) found a correlation between the age of young stellar groups in Cygnus OB2 and their Galactic longitude. If is associated with a chemical composition gradient, it could support these self-enrichment processes.
With red supergiants (RSGs) predicted to end their lives as Type IIP core collapse supernova (CCSN), their behaviour before explosion needs to be fully understood. Mass loss rates govern RSG evolution towards SN and have strong implications on the appearance of the resulting explosion. To study how the mass-loss rates change with the evolution of the star, we have measured the amount of circumstellar material around 19 RSGs in a coeval cluster. Our study has shown that mass loss rates ramp up throughout the lifetime of an RSG, with more evolved stars having mass loss rates a factor of 40 higher than early stage RSGs. Interestingly, we have also found evidence for an increase in circumstellar extinction throughout the RSG lifetime, meaning the most evolved stars are most severely affected. We find that, were the most evolved RSGs in NGC2100 to go SN, this extra extinction would cause the progenitor’s initial mass to be underestimated by up to 9M⊙.
The Of?p category was introduced more than 40 years ago to gather several Galactic stars with some odd properties. Since 2000, spectropolarimetry, high-resolution spectroscopy, long-term photometry, and X-ray observations have revealed their nature: magnetic oblique rotators - they all have magnetic fields that confine their winds. Several Of?p stars have now been detected in the Magellanic Clouds, likely the prototypes of magnetic massive stars at low metallicity. This contribution will present the most recent photometric, spectroscopic, and spectropolarimetric data, along with the first modeling of these objects.
Observations of star-forming galaxies in the distant Universe (z > 2) are starting to confirm the importance of massive stars in shaping galaxy emission and evolution. Inevitably, these distant stellar populations are unresolved, and the limited data available must be interpreted in the context of stellar population synthesis models. With the imminent launch of JWST and the prospect of spectral observations of galaxies within a gigayear of the Big Bang, the uncertainties in modelling of massive stars are becoming increasingly important to our interpretation of the high redshift Universe. In turn, these observations of distant stellar populations will provide ever stronger tests against which to gauge the success of, and flaws in, current massive star models.
We carried out a pivot experiment to select distant luminous late-type stars on the basis on their 2MASS and GLIMPSE photometry. Low-resolution infrared spectra enabled us to measure the equivalent widths (EWs) of their CO band-heads at 2.293 μm, and to confirm an extraordinarily high detection rate of red supergiants (RSGs), i.e. 61% (Messineo et al. (2016)).