59 research outputs found
Rapid radio brightening of GRB 210702A
We observed the rapid radio brightening of GRB 210702A with the Australian
Telescope Compact Array (ATCA) just 11hr post-burst, tracking early-time radio
variability over a 5hr period on ~15min timescales at 9.0, 16.7, and 21.2GHz. A
broken power-law fit to the 9.0GHz light curve showed that the 5hr flare peaked
at a flux density of 0.4+/-0.1mJy at ~13hr post-burst with a steep rise and
decline. The observed temporal and spectral evolution are not expected in the
standard internal-external shock model, where forward and reverse shock radio
emission evolves on much longer timescales. The early-time (<1day) optical and
X-ray light curves from the Neil Gehrels Swift Observatory demonstrated typical
afterglow forward shock behaviour, allowing us to use blast wave physics to
determine a likely homogeneous circumburst medium and an emitting electron
population power-law index of p=2.9+/-0.1. We suggest the early-time radio
flare is likely due to weak interstellar scintillation (ISS), which boosted the
radio afterglow emission above the ATCA sensitivity limit on minute timescales.
Using weak ISS relations, we were able to place an upper limit on the size of
the blast wave of cm in the plane of the sky, which is
consistent with the theoretical forward shock size prediction of
cm for GRB 210702A at ~13h post-burst. This represents the
earliest ISS size constraint on a GRB blast wave to date, demonstrating the
importance of rapid (<1day) radio follow-up of GRBs using several-hour
integrations to capture the early afterglow evolution, and to track
scintillation over a broad frequency range.Comment: Submitted to MNRAS 13 pages, 6 figures, 2 table
Standardized research protocols enable transdisciplinary research of climate variation impacts in corn production systems
The important questions about agriculture, climate, and sustainability have become increasingly complex and require a coordinated, multifaceted approach for developing new knowledge and understanding. A multistate, transdisciplinary project was begun in 2011 to study the potential for both mitigation and adaptation of corn-based cropping systems to climate variations. The team is measuring the baseline as well as change of the system\u27s carbon (C), nitrogen (N), and water footprints, crop productivity, and pest pressure in response to existing and novel production practices. Nine states and 11 institutions are participating in the project, necessitating a well thought out approach to coordinating field data collection procedures at 35 research sites. In addition, the collected data must be brought together in a way that can be stored and used by persons not originally involved in the data collection, necessitating robust procedures for linking metadata with the data and clearly delineated rules for use and publication of data from the overall project. In order to improve the ability to compare data across sites and begin to make inferences about soil and cropping system responses to climate across the region, detailed research protocols were developed to standardize the types of measurements taken and the specific details such as depth, time, method, numbers of samples, and minimum data set required from each site. This process required significant time, debate, and commitment of all the investigators involved with field data collection and was also informed by the data needed to run the simulation models and life cycle analyses. Although individual research teams are collecting additional measurements beyond those stated in the standardized protocols, the written protocols are used by the team for the base measurements to be compared across the region. A centralized database was constructed to meet the needs of current researchers on this project as well as for future use for data synthesis and modeling for agricultural, ecosystem, and climate sciences
Dissecting the interstellar medium of a z=6.3 galaxy: X-shooter spectroscopy and HST imaging of the afterglow and environment of the Swift GRB 210905A
The study of the properties of galaxies in the first billion years after the
Big Bang is one of the major topic of current astrophysics.
Optical/near-infrared spectroscopy of the afterglows of long Gamma-ray bursts
(GRBs) provide a powerful diagnostic tool to probe the interstellar medium
(ISM) of their host galaxies and foreground absorbers, even up to the highest
redshifts. We analyze the VLT/X-shooter afterglow spectrum of GRB 210905A,
triggered by the Swift Neil Gehrels Observatory, and detect neutral-hydrogen,
low-ionization, high-ionization, and fine-structure absorption lines from a
complex system at z=6.3118, that we associate with the GRB host galaxy. We
study the ISM properties of the host system, revealing the metallicity,
kinematics and chemical abundance pattern. The total metallicity of the z~6.3
system is [M/H]=-1.72+/-0.13, after correcting for dust-depletion and taking
into account alpha-element enhancement. In addition, we determine the overall
amount of dust and dust-to-metal mass ratio (DTM) ([Zn/Fe]_fit=0.33+/-0.09,
DTM=0.18+/-0.03). We find indications of nucleosynthesis due to massive stars
and evidence of peculiar over-abundance of aluminium. From the analysis of
fine-structure lines, we determine distances of several kpc for the
low-ionization gas clouds closest to the GRB. Those farther distances are
possibly due to the high number of ionizing photons. Using the HST/F140W image
of the GRB field, we show the GRB host galaxy as well as multiple objects
within 2" from the GRB. We discuss the galaxy structure and kinematics that
could explain our observations, also taking into account a tentative detection
of Lyman-alpha emission. Deep spectroscopic observations with VLT/MUSE and JWST
will offer the unique possibility of combining our results with the ionized-gas
properties, with the goal of better understanding how galaxies in the
reionization era form and evolve.Comment: Accepted Publication (In Press on A&A) - 22 pages, 10 figures, 6
tables - Appendix: 6 figures, 3 table
AMPK Modulation Ameliorates Dominant Disease Phenotypes of CTRP5 Variant in Retinal Degeneration
Late-onset retinal degeneration (L-ORD) is an autosomal dominant disorder caused by a missense substitution in CTRP5. Distinctive clinical features include sub-retinal pigment epithelium (RPE) deposits, choroidal neovascularization, and RPE atrophy. In induced pluripotent stem cells-derived RPE from L-ORD patients (L-ORD-iRPE), we show that the dominant pathogenic CTRP5 variant leads to reduced CTRP5 secretion. In silico modeling suggests lower binding of mutant CTRP5 to adiponectin receptor 1 (ADIPOR1). Downstream of ADIPOR1 sustained activation of AMPK renders it insensitive to changes in AMP/ATP ratio resulting in defective lipid metabolism, reduced Neuroprotectin D1(NPD1) secretion, lower mitochondrial respiration, and reduced ATP production. These metabolic defects result in accumulation of sub-RPE deposits and leave L-ORD-iRPE susceptible to dedifferentiation. Gene augmentation of L-ORD-iRPE with WT CTRP5 or modulation of AMPK, by metformin, re-sensitize L-ORD-iRPE to changes in cellular energy status alleviating the disease cellular phenotypes. Our data suggests a mechanism for the dominant behavior of CTRP5 mutation and provides potential treatment strategies for L-ORD patients. © 2021, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply
Crescimento e produção de pigmentos fotossintéticos em Achillea millefolium L. cultivada sob diferentes níveis de sombreamento e doses de nitrogênio
Swearing, Euphemisms, and Linguistic Relativity
Participants read aloud swear words, euphemisms of the swear words, and neutral stimuli while their autonomic activity was measured by electrodermal activity. The key finding was that autonomic responses to swear words were larger than to euphemisms and neutral stimuli. It is argued that the heightened response to swear words reflects a form of verbal conditioning in which the phonological form of the word is directly associated with an affective response. Euphemisms are effective because they replace the trigger (the offending word form) by another word form that expresses a similar idea. That is, word forms exert some control on affect and cognition in turn. We relate these findings to the linguistic relativity hypothesis, and suggest a simple mechanistic account of how language may influence thinking in this context
The Faces in Infant-Perspective Scenes Change over the First Year of Life
Mature face perception has its origins in the face experiences of infants. However, little is known about the basic statistics of faces in early visual environments. We used head cameras to capture and analyze over 72,000 infant-perspective scenes from 22 infants aged 1-11 months as they engaged in daily activities. The frequency of faces in these scenes declined markedly with age: for the youngest infants, faces were present 15 minutes in every waking hour but only 5 minutes for the oldest infants. In general, the available faces were well characterized by three properties: (1) they belonged to relatively few individuals; (2) they were close and visually large; and (3) they presented views showing both eyes. These three properties most strongly characterized the face corpora of our youngest infants and constitute environmental constraints on the early development of the visual system
The Gamow Explorer: A Gamma-Ray Burst Observatory to study the high redshift universe and enable multi-messenger astrophysics
UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XXII 2021San Diego1 August 2021 through 5 August 2021Code 172616.-- Proceedings of SPIE - The International Society for Optical Engineering, Volume 118212021 Article number 1182109The Gamow Explorer will use Gamma Ray Bursts (GRBs) to: 1) probe the high redshift universe (z < 6) when the first stars were born, galaxies formed and Hydrogen was reionized; and 2) enable multi-messenger astrophysics by rapidly identifying Electro-Magnetic (IR/Optical/X-ray) counterparts to Gravitational Wave (GW) events. GRBs have been detected out to z ∼ 9 and their afterglows are a bright beacon lasting a few days that can be used to observe the spectral fingerprints of the host galaxy and intergalactic medium to map the period of reionization and early metal enrichment. Gamow Explorer is optimized to quickly identify high-z events to trigger follow-up observations with JWST and large ground-based telescopes. A wide field of view Lobster Eye X-ray Telescope (LEXT) will search for GRBs and locate them with arc-minute precision. When a GRB is detected, the rapidly slewing spacecraft will point the 5 photometric channel Photo-z Infra-Red Telescope (PIRT) to identify high redshift (z < 6) long GRBs within 100s and send an alert within 1000s of the GRB trigger. An L2 orbit provides < 95% observing efficiency with pointing optimized for follow up by the James Webb Space Telescope (JWST) and ground observatories. The predicted Gamow Explorer high-z rate is <10 times that of the Neil Gehrels Swift Observatory. The instrument and mission capabilities also enable rapid identification of short GRBs and their afterglows associated with GW events. The Gamow Explorer will be proposed to the 2021 NASA MIDEX call and if approved, launched in 2028With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709Peer reviewe
The Gamow Explorer: A Gamma-Ray Burst Observatory to study the high redshift universe and enable multi-messenger astrophysics
UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XXII 2021San Diego1 August 2021 through 5 August 2021Code 172616.-- Proceedings of SPIE - The International Society for Optical Engineering, Volume 118212021 Article number 1182109The Gamow Explorer will use Gamma Ray Bursts (GRBs) to: 1) probe the high redshift universe (z < 6) when the first stars were born, galaxies formed and Hydrogen was reionized; and 2) enable multi-messenger astrophysics by rapidly identifying Electro-Magnetic (IR/Optical/X-ray) counterparts to Gravitational Wave (GW) events. GRBs have been detected out to z ∼ 9 and their afterglows are a bright beacon lasting a few days that can be used to observe the spectral fingerprints of the host galaxy and intergalactic medium to map the period of reionization and early metal enrichment. Gamow Explorer is optimized to quickly identify high-z events to trigger follow-up observations with JWST and large ground-based telescopes. A wide field of view Lobster Eye X-ray Telescope (LEXT) will search for GRBs and locate them with arc-minute precision. When a GRB is detected, the rapidly slewing spacecraft will point the 5 photometric channel Photo-z Infra-Red Telescope (PIRT) to identify high redshift (z < 6) long GRBs within 100s and send an alert within 1000s of the GRB trigger. An L2 orbit provides < 95% observing efficiency with pointing optimized for follow up by the James Webb Space Telescope (JWST) and ground observatories. The predicted Gamow Explorer high-z rate is <10 times that of the Neil Gehrels Swift Observatory. The instrument and mission capabilities also enable rapid identification of short GRBs and their afterglows associated with GW events. The Gamow Explorer will be proposed to the 2021 NASA MIDEX call and if approved, launched in 2028With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709Peer reviewe
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