Based on phase-resolved broadband spectroscopy using XMM-Newton and NuSTAR, we report on a potential cyclotron resonant scattering feature (CRSF) at E ∼ 13 keV in the pulsed spectrum of the recently ...discovered ultraluminous X-ray source (ULX) pulsar NGC 300 ULX1. If this interpretation is correct, the implied magnetic field of the central neutron star is B ∼ 1012 G (assuming scattering by electrons), similar to that estimated from the observed spin-up of the star, and also similar to known Galactic X-ray pulsars. We discuss the implications of this result for the connection between NGC 300 ULX1 and the other known ULX pulsars, particularly in light of the recent discovery of a likely proton cyclotron line in another ULX, M51 ULX-8.
Sea-level rise is a consequence of climate change that can impact the ecological and physiological changes of coastal, ground-dwelling species. Sea-level rise has a potential to inundate birds, ...rodents, spiders, and insects that live on the ground in coastal areas. Yet, there is still much to be learned concerning the specifics of these impacts. The red imported fire ant Solenopsis invicta (Buren) excavates soil for its home and is capable of surviving flooding. Because of their ground-dwelling life history and rapid reproduction, fire ants make an ideal model for discovery and prediction of changes that may be due to sea-level rise. There are up to 500,000 individuals in a colony, and these invasive ants naturally have a painful sting. However, observations suggest that colonies of fire ants that dwell in tidally-influenced areas are more aggressive with more frequent stings and more venom injected per sting (behavioral and physiological changes) than those located inland. This may be an adaption to sea-level rise. Therefore, the objective of this study is to elucidate differences in inland and coastal defensiveness via micro-dissection and comparison of head width, head length, stinger length, and venom sac volume. But first because fire ants' ability to raft on brackish tidal water is unknown, it had to be determined if fire ants could indeed raft in brackish water and examine the behavior differences between those flooded with freshwater vs. saltwater.
To test the coastal-aggression hypothesis, inland colonies and coastal colonies, which experience relatively greater amounts of flooding, specifically regular tidal and windblown water and oscillations (i.e. El Nińo Southern Oscillation) from the Gulf of Mexico, were collected. To mimic sea-level rise, the colonies were flooded in salinities that correspond to both their collection site and conditions found in a variety of locales and situations (such as storm surge from a tropical storm). Individual ants were immediately taken from each colony for dissection before flooding, 1-hour into flooding, and 24-hours into flooding.
Fire ants use their venom to defend themselves and to communicate alarm or aggression. Dissections and measurement of heads, venom sacs, and stingers revealed both coastal and inland colonies experience an increase in venom sac volume after 24 hours; in fact coastal colonies increased their venom volume by 75% after 24 h of flooding Whether this venom sac enlargement is due to diffusion of water or venom sac production is unknown. These ground-dwelling ants exhibit physiological and behavioral adaptations to ongoing sea-level rise possibly indicating that they are responding to increased flooding. Fire ants will raft on high-salinity water; and sea-level rise may cause stings by flooded ants to be more severe because of increased venom volume.
SN2010da/NGC 300 ULX-1 was first detected as a supernova impostor in 2010 May and was recently discovered to be a pulsating ultraluminous X-ray source. In this Letter, we present Very Large ...Telescope/X-shooter spectra of this source obtained in 2018 October, covering the wavelength range 350-2300 nm. The J- and H-bands clearly show the presence of a red supergiant (RSG) donor star that is best matched by a MARCS stellar atmosphere with Teff = 3650-3900 K and log(Lbol/L ) = 4.25 0.10, which yields a stellar radius R = 310 70R . To fit the full spectrum, two additional components are required: a blue excess that can be fitted either by a hot blackbody (T 20,000 K) or a power law (spectral index 4) and is likely due to X-ray emission reprocessed in the outer accretion disk or the donor star; and a red excess that is well fitted by a blackbody with a temperature of ∼1100 K, and is likely due to warm dust in the vicinity of SN2010da. The presence of an RSG in this system implies an orbital period of at least 0.8-2.1 yr, assuming Roche-lobe overflow. Given the large donor-to-compact object mass ratio, orbital modulations of the radial velocity of the RSG are likely undetectable. However, the radial velocity amplitude of the neutron star is large enough (up to 40-60 km s−1) to potentially be measured in the future, unless the system is viewed at a very unfavorable inclination.
Bright and photostable fluorescence from nitrogen-vacancy (NV) centers is demonstrated in unprocessed detonation nanodiamond particle aggregates. The optical properties of these particles is analyzed ...using confocal fluorescence microscopy and spectroscopy, time resolved fluorescence decay measurements, and optically detected magnetic resonance experiments. Two particle populations with distinct optical properties are identified and compared to high-pressure high-temperature (HPHT) fluorescent nanodiamonds. We find that the brightness of one detonation nanodiamond particle population is on the same order as that of highly processed fluorescent 100 nm HPHT nanodiamonds. Our results may open the path to a simple and up-scalable route for the production of fluorescent NV nanodiamonds for use in bioimaging applications.
Dust formation in supernova ejecta is currently the leading candidate to explain the large quantities of dust observed in the distant, early universe. However, it is unclear whether the ejecta-formed ...dust can survive the hot interior of the supernova remnant (SNR). We present infrared observations of ∼0.02 solar masses of warm (∼100 kelvin) dust seen near the center of the ∼10,000-year-old Sagittarius A East SNR at the Galactic center. Our findings indicate the detection of dust within an older SNR that is expanding into a relatively dense surrounding medium (electron density ∼103 centimeters–3) and has survived the passage of the reverse shock. The results suggest that supernovae may be the dominant dust-production mechanism in the dense environment of galaxies of the early universe.
The Sgr A-H H ii regions are a collection of sources that may represent one of the most recent sites of star formation in the Galactic center (GC). Examining these H ii regions provides important ...information on the prevalence and distribution of massive stars in the region and may provide clues on the origin of other massive field stars throughout the GC. In this work, we present infrared imaging observations of the Sgr A-H H ii regions taken with the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST) at 19.7, 25.2, 31.5, and 37.1 m. These data provide high angular resolution maps (∼4″) of the sources, which allow us to study the morphology of spatially extended H ii regions in detail. The wavelength coverage of FORCAST also supplies important constraints on the dust mass, temperature, and luminosity of the sources. We produce spectral energy distribution models using DustEM to measure the luminosity and dust mass, which range from ∼3 × 103 to 6 × 105 L and from ∼6 × 10−4 to 3 × 10−1 M , respectively. Analysis of dust temperatures in the four spatially extended H ii regions (H1, H2, H3, and H5) shows that three of these objects require multiple heating sources, and we identify potential stellar candidates. We also compare the size and morphology of the H ii regions and demonstrate that the properties of H2 are consistent with in situ star formation. Lastly, we identify nine additional sources that may be part of the H complex and provide initial characterizations of their infrared emission.
We present 19.7, 31.5, and 37.1 mu m images of the inner 6 pc of the Galactic center of the Milky Way with a spatial resolution of 3".2-4".6 taken by the Faint Object Infrared Camera on the ...Stratospheric Observatory for Infrared Astronomy. The images reveal in detail the "clumpy" structure of the circumnuclear ring (CNR)-the inner edge of the molecular torus orbiting the supermassive black hole at the Galactic center-and the prominent streamers of hot, ionized gas and dust within the CNR that compose the H II region Sgr A West. The CNR exhibits features of a classic H II region: the dust emission at 19.7 mu m closely traces the ionized gas emission observed in the radio while the 31.5 and 37.1 mu m emission traces the photo-dissociation region beyond the ionized gas. The 19.7/37.1 color temperature map reveals a radial temperature gradient across the CNR with temperatures ranging from 65 to 85 K, consistent with the prevailing paradigm in which the dust is centrally heated by the inner cluster of hot, young stars. We model the 37.1 mu m intensity of the CNR as an inclined (thetai = 67degrees) ring with a thickness and radius of 0.34 pc and 1.4 pc, respectively, and find that it is consistent with the observed 37.1 mu m map of the CNR. The 37.1 mu m optical depth map also reveals the clumpy dust distribution of the CNR and implies a total gas mass of ~610 M sub(middot in circle). Dense (5-9 x 10 super(4) cm super(-3)) clumps with an FWHM of ~0.15 pc exist along the inner edge of the CNR and shadow the material deeper into the ring. We find that the clumps are unlikely to be long-lived structures since they are not dense enough to be stable against tidal shear from the supermassive black hole and will be sheared out on a timescale of an orbital period (~10 super(5) yr).
Thioamides antithyroid‐drugs (ATDs) are important in hyperthyroid disease management. Identification of the susceptibility locus of ATD‐induced agranulocytosis is important for clinical management. ...We performed a genome‐wide association study (GWAS) involving 20 patients with ATD‐induced agranulocytosis and 775 healthy controls. The top finding was further replicated. A single‐nucleotide polymorphism (SNP), rs185386680, showed the strongest association with ATD‐induced agranulocytosis in GWAS (odds ratio (OR) = 36.4; 95% confidence interval (CI) = 12.8–103.7; P = 1.3 × 10‐24) and replication (OR = 37; 95% CI = 3.7–367.4; P = 9.6 × 10‐7). HLA‐B*38:02:01 was in complete linkage disequilibrium with rs185386680. High‐resolution HLA typing confirmed that HLA‐B*38:02:01 was associated with carbimazole (CMZ)/methimazole (MMI)‐induced agranulocytosis (OR = 265.5; 95% CI = 27.9–2528.0; P = 2.5 × 10‐14), but not associated with propylthiouracil (PTU). The positive and negative predictive values of HLA‐B*38:02:01 in predicting CMZ/MMI‐induced agranulocytosis were 0.07 and 0.999. Approximately 211 cases need to be screened to prevent one case. Screening for the risk allele will be useful in preventing agranulocytosis in populations in which the frequency of the risk allele is high.
Barrett's esophagus is the only known mucosal precursor for the highly malignant esophageal adenocarcinoma. Malignant degeneration of non-dysplastic Barrett's esophagus occurs in < 0.6% per year in ...Dutch surveillance cohorts. Therefore, it has been proposed to increase the surveillance intervals from 3 to 5 years, potentially increasing development of advanced stage interval cancers. To prevent such cases robust biomarkers for more optimal stratification over longer follow up periods for non-dysplastic Barrett's patients are required. In this multi-center study, aberrations for chromosomes 7, 17, and structural abnormalities for c-MYC, CDKN2A, TP53, Her-2/neu and 20q assessed by DNA fluorescence in situ hybridization on brush cytology specimens, were used to determine marker scores and to perform clonal diversity measurements, as described previously. In this study, these genetic biomarkers were combined with clinical variables and analyzed to obtain the most efficient cancer prediction model after an extended period of follow-up (median time of 7 years) by applying Cox regression modeling, bootstrapping and leave-one-out analyses. A total of 334 patients with Barrett's esophagus without dysplasia from 6 community hospitals (n = 220) and one academic center (n = 114) were included. The annual progression rate to high grade dysplasia and/or esophageal adenocarcinoma was 1.3%, and to adenocarcinoma alone 0.85%. A prediction model including age, Barrett circumferential length, and a clonicity score over the genomic set including chromosomes 7, 17, 20q and c-MYC, resulted in an area under the curve of 0.88. The sensitivity and specificity of this model were 0.91 and 0.38. The positive and negative predictive values were 0.13 (95% CI 0.09 to 0.19) and 0.97 (95% CI 0.93 to 0.99). We propose the implementation of the model to identify non-dysplastic Barrett's patients, who are required to remain in surveillance programs with 3-yearly surveillance intervals from those that can benefit from less frequent or no surveillance.
The objectives of this tutorial are as follows: 1) to help students and researchers develop a basic understanding of how pulsed-power systems are used to create high-energy-density (HED) matter; 2) ...to develop a basic understanding of a new, compact, and efficient pulsed-power technology called linear transformer drivers (LTDs); 3) to understand why LTDs are an attractive technology for driving HED physics (HEDP) experiments; 4) to contrast LTDs with the more traditional Marx-generator/pulse-forming-line approach to driving HEDP experiments; and 5) to briefly review the history of LTD technology as well as some of the LTD-driven HEDP research presently underway at universities and research laboratories across the globe. This invited tutorial is part of the Mini-Course on Charged Particle Beams and High-Powered Pulsed Sources, held in conjunction with the 44th International Conference on Plasma Science in May of 2017.
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