Abstract
We observed HD 19467 B with JWST’s NIRCam in six filters spanning 2.5–4.6
μ
m with the long-wavelength bar coronagraph. The brown dwarf HD 19467 B was initially identified through a ...long-period trend in the radial velocity of the G3V star HD 19467. HD 19467 B was subsequently detected via coronagraphic imaging and spectroscopy, and characterized as a late-T type brown dwarf with an approximate temperature ∼1000 K. We observed HD 19467 B as a part of the NIRCam GTO science program, demonstrating the first use of the NIRCam Long Wavelength Bar coronagraphic mask. The object was detected in all six filters (contrast levels of 2 × 10
−4
to 2 × 10
−5
) at a separation of 1.″6 using angular differential imaging and synthetic reference differential imaging. Due to a guide star failure during the acquisition of a preselected reference star, no reference star data were available for post-processing. However, reference differential imaging was successfully applied using synthetic point-spread functions developed from contemporaneous maps of the telescope’s optical configuration. Additional radial velocity data (from Keck/HIRES) are used to constrain the orbit of HD 19467 B. Photometric data from TESS are used to constrain the properties of the host star, particularly its age. NIRCam photometry, spectra, and photometry from the literature, and improved stellar parameters are used in conjunction with recent spectral and evolutionary substellar models to derive the physical properties of HD 19467 B. Using an age of 9.4 ± 0.9 Gyr inferred from spectroscopy, Gaia astrometry, and TESS asteroseismology, we obtain a model-derived mass of 62 ± 1
M
J
, which is consistent within 2
σ
with the dynamically derived mass of
81
−
12
+
14
M
J
.
Plasma waves generated in the wake of intense, relativistic laser1,2 or particle beams3,4 can accelerate electron bunches to gigaelectronvolt energies in centimetre-scale distances. This allows the ...realization of compact accelerators with emerging applications ranging from modern light sources such as the free-electron laser to energy frontier lepton colliders. In a plasma wakefield accelerator, such multi-gigavolt-per-metre wakefields can accelerate witness electron bunches that are either externally injected5,6 or captured from the background plasma7,8. Here we demonstrate optically triggered injection9–11 and acceleration of electron bunches, generated in a multi-component hydrogen and helium plasma employing a spatially aligned and synchronized laser pulse. This ‘plasma photocathode’ decouples injection from wake excitation by liberating tunnel-ionized helium electrons directly inside the plasma cavity, where these cold electrons are then rapidly boosted to relativistic velocities. The injection regime can be accessed via optical11 density down-ramp injection12–16 and is an important step towards the generation of electron beams with unprecedented low transverse emittance, high current and 6D-brightness17. This experimental path opens numerous prospects for transformative plasma wakefield accelerator applications based on ultrahigh-brightness beams.
There is a fundamental difference between the ways in which ecologists and lawyers view uncertainty: in the study of ecology, uncertainty provides a catalyst for exploration, whereas uncertainty is ...antithetical to the rule of law. This issue is particularly troubling in environmental management, where the tensions between law and ecology become apparent. Rather than acknowledge uncertainties in management actions, legal frameworks often force a false sense of certainty in linking cause and effect. While adaptive management has been developed to deal with uncertainty, laws and legal wrangling can be obstacles to implementation. In this article, we recommend resilience-based governance - "adaptive governance" - as a means to begin bridging the gap between law and ecology.
Low concentrations of carbon monoxide (CO) can protect tissues against ischemia–reperfusion (I–R) injury. We have recently identified a novel class of compounds, CO-releasing molecules (CO-RMs), ...which exert important pharmacological activities by carrying and delivering CO to biological systems. Here, we examined the possible beneficial effects of CO liberated from CO-RMs on the damage inflicted by cold storage and I–R in isolated perfused kidneys. Hemodynamic and biochemical parameters as well as mitochondrial respiration were measured in isolated perfused rabbit kidneys that were previously flushed with CO-RMs and stored at 4°C for 24 h. Two water-soluble CO-RMs were tested: (1) sodium boranocarbonate (CORM-A1), a boron-containing carbonate that releases CO at a slow rate, and (2) tricarbonylchloro(glycinato)ruthenium(II) (CORM-3), a transition metal carbonyl that liberates CO very rapidly in solution. Kidneys flushed with Celsior solution supplemented with CO-RMs (50 μM) and stored at 4°C for 24 h displayed at reperfusion a significantly higher perfusion flow rate (PFR), glomerular filtration rate, and sodium and glucose reabsorption rates compared to control kidneys flushed with Celsior solution alone. Addition of 1H-1,2,4oxadiazolo4,3-alphaquinoxalin-1-one (ODQ), a guanylate cyclase inhibitor, prevented the increase in PFR mediated by CO-RMs. The respiratory control index from kidney mitochondria treated with CO-RMs was also markedly increased. Notably, renal protection was lost when kidneys were flushed with Celsior containing an inactive compound (iCO-RM), which had been deliberately depleted of CO. CO-RMs are effective therapeutic agents that deliver CO during kidney cold preservation and can be used to ameliorate vascular activity, energy metabolism and renal function at reperfusion.
The detection of high-redshift ( ) blazars enables the study of the evolution of the most luminous relativistic jets over cosmic time. More importantly, high-redshift blazars tend to host massive ...black holes and can be used to constrain the space density of heavy black holes in the early universe. Here, we report the first detection with the Fermi-Large Area Telescope of five γ-ray-emitting blazars beyond z = 3.1, more distant than any blazars previously detected in γ-rays. Among these five objects, NVSS J151002+570243 is now the most distant known γ-ray-emitting blazar at z = 4.31. These objects have steeply falling γ-ray spectral energy distributions (SEDs), and those that have been observed in X-rays have a very hard X-ray spectrum, both typical of powerful blazars. Their Compton dominance (ratio of the inverse Compton to synchrotron peak luminosities) is also very large ( ). All of these properties place these objects among the most extreme members of the blazar population. Their optical spectra and the modeling of their optical-UV SEDs confirm that these objects harbor massive black holes ( ). We find that, at , the space density of black holes hosted in radio-loud and radio-quiet active galactic nuclei are similar, implying that radio-loudness may play a key role in rapid black hole growth in the early universe.
There is an urgent need to understand the pathways and processes underlying Alzheimer's disease (AD) for early diagnosis and development of effective treatments. This study was aimed to investigate ...Alzheimer's dementia using an unsupervised lipid, protein and gene multi-omics integrative approach.
A lipidomics dataset comprising 185 AD patients, 40 mild cognitive impairment (MCI) individuals and 185 controls, and two proteomics datasets (295 AD, 159 MCI and 197 controls) were used for weighted gene co-expression network analyses (WGCNA). Correlations of modules created within each modality with clinical AD diagnosis, brain atrophy measures and disease progression, as well as their correlations with each other, were analyzed. Gene ontology enrichment analysis was employed to examine the biological processes and molecular and cellular functions of protein modules associated with AD phenotypes. Lipid species were annotated in the lipid modules associated with AD phenotypes. The associations between established AD risk loci and the lipid/protein modules that showed high correlation with AD phenotypes were also explored.
Five of the 20 identified lipid modules and five of the 17 identified protein modules were correlated with clinical AD diagnosis, brain atrophy measures and disease progression. The lipid modules comprising phospholipids, triglycerides, sphingolipids and cholesterol esters were correlated with AD risk loci involved in immune response and lipid metabolism. The five protein modules involved in positive regulation of cytokine production, neutrophil-mediated immunity, and humoral immune responses were correlated with AD risk loci involved in immune and complement systems and in lipid metabolism (the APOE ε4 genotype).
Modules of tightly regulated lipids and proteins, drivers in lipid homeostasis and innate immunity, are strongly associated with AD phenotypes.
The effects of monensin on transition cow metabolism may be dependent on modulation of feeding behavior, rumen pH, and expression of key metabolic genes. Multiparous Holstein cows were used to ...determine the effects of monensin (400mg/cow daily) on these variables. Cows were randomly assigned, based on calving date, to control or monensin treatments (n=16 per treatment) 21 d before their expected calving date, and cows remained on treatments through 21 d postpartum. Feeding behavior and water intake data were collected daily. Liver biopsies were conducted after assessing BCS and BW on d −21, −7, 1, 7, and 21 relative to calving for analysis of triglyceride (TG) content as well as mRNA abundance of cytosolic phosphoenolpyruvate carboxykinase, carnitine palmitoyltransferase 1a, and apolipoprotein B. Blood samples were collected 21, 7, and 4 d before expected calving and 1 (day of calving), 4, 7, 14, and 21 d postpartum for nonesterified fatty acid, β-hydroxybutyrate, glucose, insulin, and haptoglobin analyses. Ruminal pH was collected every 5min on d 1 through 6 postpartum via a wireless indwelling probe. On d 7 postpartum, a caffeine clearance test was performed to assess liver function. Data were analyzed using mixed models with repeated measures over time. Monensin decreased mean plasma β-hydroxybutyrate (734 vs. 616±41μM) and peak concentrations (1,076 vs. 777±70μM on d 4 postpartum). Monensin also decreased time between meals prepartum (143 vs. 126±5.0min) and postpartum (88.8 vs. 81.4±2.9min), which was likely related to a smaller ruminal pH standard deviation in the first day after cows changed to a lactation ration (0.31 vs. 0.26±0.015). Monensin also increased liver mRNA abundance of carnitine palmitoyltransferase 1a (0.10 vs. 0.15±0.002 arbitrary units), which corresponded to a slower rate of liver TG accumulation from d −7 to +7 (412 vs. 128±83mg of TG/g of protein over this time period). No significant effects of monensin supplementation were observed on milk production, liver cytosolic phosphoenolpyruvate carboxykinase, apolipoprotein B, plasma nonesterified fatty acid, glucose, insulin, or haptoglobin. No effects on disease incidence were detected, but sample size was small for detecting such effects. Overall, results confirm that the effects of monensin on transition cows extend beyond altered propionate flux.
The Active Magnetosphere and Planetary Electrodynamics Response Experiment uses magnetic field data from the Iridium constellation to derive the global Birkeland current distribution every 10 min. We ...examine cases in which the interplanetary magnetic field (IMF) rotated from northward to southward resulting in onsets of the Birkeland currents. Dayside Region 1/2 currents, totaling ~25% of the final current, appear within 20 min of the IMF southward turning and remain steady. Onset of nightside currents occurs 40 to 70 min after the dayside currents appear. Thereafter, the currents intensify at dawn, dusk, and on the dayside, yielding a fully formed Region 1/2 system ~30 min after the nightside onset. The results imply that the dayside Birkeland currents are driven by magnetopause reconnection, and the remainder of the system forms as magnetospheric return flows start and progress sunward, ultimately closing the Dungey convection cycle.
Key Points
Dayside currents, both Regions 1 and 2, form promptly with solar wind forcing
The onset of nightside currents, Regions 1 and 2, coincides with substorm onset
Most of the current system develops from the nightside after onset
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