Abstract
Gravitational-wave detectors are starting to reveal the redshift evolution of the binary black hole (BBH) merger rate,
R
BBH
(
z
). We make predictions for
R
BBH
(
z
) as a function of black ...hole mass for systems originating from isolated binaries. To this end, we investigate correlations between the delay time and black hole mass by means of the suite of binary population synthesis simulations,
COMPAS
. We distinguish two channels: the common envelope (CE), and the stable Roche-lobe overflow (RLOF) channel, characterized by whether the system has experienced a common envelope or not. We find that the CE channel preferentially produces BHs with masses below about 30
M
⊙
and short delay times (
t
delay
≲ 1 Gyr), while the stable RLOF channel primarily forms systems with BH masses above 30
M
⊙
and long delay times (
t
delay
≳ 1 Gyr). We provide a new fit for the metallicity-dependent specific star formation rate density based on the Illustris TNG simulations, and use this to convert the delay time distributions into a prediction of
R
BBH
(
z
). This leads to a distinct redshift evolution of
R
BBH
(
z
) for high and low primary BH masses. We furthermore find that, at high redshift,
R
BBH
(
z
) is dominated by the CE channel, while at low redshift, it contains a large contribution (∼40%) from the stable RLOF channel. Our results predict that, for increasing redshifts, BBHs with component masses above 30
M
⊙
will become increasingly scarce relative to less massive BBH systems. Evidence of this distinct evolution of
R
BBH
(
z
) for different BH masses can be tested with future detectors.
The theory for single stellar evolution predicts a gap in the mass distribution of black holes (BHs) between approximately 45 and 130 , the so-called "pair-instability mass gap." We examine whether ...BHs can pollute the gap after accreting from a stellar companion. To this end, we simulate the evolution of isolated binaries using a population synthesis code, where we allow for super-Eddington accretion. Under our most extreme assumptions, we find that at most about 2% of all merging binary BH systems contains a BH with a mass in the pair-instability mass gap, and we find that less than 0.5% of the merging systems has a total mass larger than 90 . We find no merging binary BH systems with a total mass exceeding 100 . We compare our results to predictions from several dynamical pathways to pair-instability mass gap events and discuss the distinguishable features. We conclude that the classical isolated binary formation scenario will not significantly contribute to the pollution of the pair-instability mass gap. The robustness of the predicted mass gap for the isolated binary channel is promising for the prospective of placing constraints on (i) the relative contribution of different formation channels, (ii) the physics of the progenitors including nuclear reaction rates, and, tentatively, (iii) the Hubble parameter.
Catalysts are often added to solid propellant formulations to tailor burning rates. Nanocatalysts can increase propellant burning rates over standard catalyst sizes due to the increase in surface ...area per unit weight. However, the increased surface area that the binder must wet can be prohibitive if large amounts of nanocatalysts are used. Additionally, agglomeration of the nanocatalyst can result in micron-scale particles, reducing catalyst effectiveness. In this study a nanoscale iron oxide catalyst has been used to decorate graphene. By decorating graphene with the catalyst, nanoscale features are kept but the catalyst is stabilized to reduce agglomeration. Changes in burning rate between the catalyzed and uncatalyzed propellants are investigated. The effect on burning rate of encapsulating the catalyst inside the fine AP crystals compared to propellants where it is added to the binder is also investigated. We also compare propellants with decorated graphene and propellants with undecorated graphene catalysts. The three comparisons are made for two different graphene preparation methods. It is found that the highest burning rates occur in propellants where the graphene is decorated with catalyst and encapsulated in the fine AP. The next highest burning rates occur in propellants with decorated graphene that is physically mixed into the propellant. The lowest burning rates are found in propellants where the graphene is undecorated, where there is little difference between encapsulated or physically mixed graphene blanks, or compared to a baseline propellant. Burning rates are found to be similar between graphene preparation methods considered.
The Seyfert 1 galaxy Arp 151 was monitored as part of three reverberation mapping campaigns spanning 2008-2015. We present modeling of these velocity-resolved reverberation mapping data sets using a ...geometric and dynamical model for the broad-line region (BLR). By modeling each of the three data sets independently, we infer the evolution of the BLR structure in Arp 151 over a total of 7 yr and constrain the systematic uncertainties in nonvarying parameters such as the black hole mass. We find that the BLR geometry of a thick disk viewed close to face-on is stable over this time, although the size of the BLR grows by a factor of ∼2. The dynamics of the BLR are dominated by inflow, and the inferred black hole mass is consistent for the three data sets, despite the increase in BLR size. Combining the inference for the three data sets yields a black hole mass and statistical uncertainty of log10( / ) = with a standard deviation in individual measurements of 0.13 dex.
•LDPE is proposed as a robust, cost-effective binding agent for beneficiating low-grade coal fines into briquettes.•Interaction effects between southern Indiana coal and LDPE are noted via ...TGA/DSC.•Addition of LDPE increases flame temperatures and assists ignition of blends.•Addition of LDPE increases combustion efficiency of coal under identical operating conditions.
Significant ecological concerns and attractive financial opportunities are raised by growing deposits of waste coal fines in the United States. These fines can potentially be utilized by extrusion or roller press briquetting along with a binder to impart mechanical strength and water resistance to the briquettes. This research focuses on low density polyethylene (LDPE) as a binder, which is abundant in waste streams and possesses desirable energy, waterproofing, and binding characteristics. The goal of this study was to characterize a briquetted fuel made from waste coal and LDPE that may be an economic and ecologic viable substitute for conventional stoker coal. Thermal and mechanical analyses of the fuel were conducted using standard techniques including compression and attrition testing, bomb calorimetry, thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), and lab-scale combustion testing. The results of this work indicate that LDPE is an effective binding agent when incorporated at suitable concentrations and particle sizes. Addition of 10% LDPE increases the measured higher heating value of the coal from 21.9MJ/kg to 24.3MJ/kg and imparts water resistance to the compacted fuel. Differential scanning calorimetry of coal/LDPE mixtures indicates a significant interaction, consistent with prior research. Addition of LDPE in concentrations as low as 5% eases ignition of the fuel by significantly lowering the onset temperature of exothermic decomposition. Lab-scale combustion experimentation confirms that ignition characteristics of the parent coal are positively influenced by the addition of LDPE.
Background & Aims T cells play a critical role in viral infection. We examined whether T-cell effector and regulatory responses can define clinical stages of chronic hepatitis B (CHB). Methods We ...enrolled 200 adults with CHB who participated in the National Institutes of Health−supported Hepatitis B Research Network from 2011 through 2013 and 20 uninfected individuals (controls). Peripheral blood lymphocytes from these subjects were analyzed for T-cell responses (proliferation and production of interferon gamma and interleukin 10) to overlapping hepatitis B virus (HBV) peptides (preS, S, preC, core, and reverse transcriptase), influenza matrix peptides, and lipopolysaccharide. T-cell expression of regulatory markers FOXP3, programmed death-1, and cytotoxic T lymphocyte-associated antigen-4 was examined by flow cytometry. Immune measures were compared with clinical parameters, including physician-defined immune-active, immune-tolerant, or inactive CHB phenotypes, in a blinded fashion. Results Compared with controls, patients with CHB had weak T-cell proliferative, interferon gamma, and interleukin 10 responses to HBV, with increased frequency of circulating FOXP3+ CD127− regulatory T cells and CD4+ T-cell expression of programmed death-1 and cytotoxic T lymphocyte-associated antigen-4. T-cell measures did not clearly distinguish between clinical CHB phenotypes, although the HBV core-specific T-cell response was weaker in hepatitis B e antigen (HBeAg)+ than HBeAg− patients (percent responders: 3% vs 23%; P = .00008). Although in vitro blockade of programmed death-1 or cytotoxic T lymphocyte-associated antigen-4 increased T-cell responses to HBV, the effect was weaker in HBeAg+ than HBeAg− patients. Furthermore, T-cell responses to influenza and lipopolysaccharide were weaker in CHB patients than controls. Conclusions HBV persists with virus-specific and global T-cell dysfunction mediated by multiple regulatory mechanisms, including circulating HBeAg, but without distinct T-cell−based immune signatures for clinical phenotypes. These findings suggest additional T-cell−independent or regulatory mechanisms of CHB pathogenesis that warrant further investigation.
Numerous prevalence studies and outbreaks of
infection have been extensively reported in shellfish and crustaceans. Information on the quantitative detection of
in finfish species is limited. In this ...study, short mackerels (
) obtained from different retail marketplaces were monitored with the presence of total and pathogenic strains of
. Out of 130 short mackerel samples, 116 (89.2%) were detected with the presence of total
and microbial loads of total
ranging from <3 to >10
MPN/g. Prevalence of total
was found highest in wet markets (95.2%) followed by minimarkets (89.1%) and hypermarkets (83.3%). Pathogenic
strains (
+ and/or
+) were detected in 16.2% (21 of 130) of short mackerel samples. The density of
+
strains were examined ranging from 3.6 to >10
MPN/g and microbial loads of
strains positive for both
and
were found ranging from 300 to 740 MPN/g. On the other hand, antibiotic susceptibility profiles of
strains isolated from short mackerels were determined through disc diffusion method in this study. Assessment of antimicrobial susceptibility profile of
revealed majority of the isolates were highly susceptible to ampicillin sulbactam, meropenem, ceftazidime, and imipenem, but resistant to penicillin G and ampicillin. Two isolates (2.99%) exhibited the highest multiple antibiotic resistance (MAR) index value of 0.41 which shown resistance to 7 antibiotics. Results of the present study demonstrated that the occurrence of pathogenic
strains in short mackerels and multidrug resistance of
isolates could be a potential public health concerns to the consumer. Furthermore, prevalence data attained from the current study can be further used to develop a microbial risk assessment model to estimate health risks associated with the consumption of short mackerels contaminated with pathogenic
.
► Peak temperatures measured (up to 3200K) in an oxy-fuel boiler using an inverse technique. ► Flame speed and spectral intensity quantified for a variety of conditions in laboratory burner. ► ...Spherical flame speed ranged between 0.8m/s and 4.1m/s in laboratory experiments. ► Thermo-chemical equilibrium calculations performed on oxy-coal to quantify trends.
Our focus is on oxy-fuel combustion and its associated heat transfer properties, especially radiative transport. Spectral intensity measurements have been obtained in a laboratory setting as well as on a pilot scale boiler. The pilot-scale experiments utilize a boiler retrofitted for oxy-fuel that operates at a temperature ranging to over 3000K. Due to such high temperatures, temperature measurements of the flame are not possible with probes and are instead inferred by a process called inverse radiation interpretation. Multiple operating conditions are considered while noting that the temperature profiles indicate peak temperatures ranging from 2400K to 3200K. Laboratory-scale dust cloud combustion studies are also performed that characterize the radiative properties and flame speed while varying the coal type, particle size and oxygen content. Laboratory flame speed and spectral intensity is seen to increase with higher levels of oxygen, higher volatile content in coals, smaller particle sizes and diluents with lower specific heats. Flame speed is seen to range between 0.8m/s and 4.1m/s in these experiments. Lastly, chemical equilibrium calculations are presented. Equilibrium product temperature and species were shown with varying parameters. The maximum temperature for Illinois #6 coal and an Indonesian low sulfur bituminous coal is 2954K and 2959K respectively.
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