ORCID Profile
0000-0002-4378-9043
Current Organisation
The University of Edinburgh
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Publisher: Copernicus GmbH
Date: 23-09-2022
DOI: 10.5194/EPSC2022-989
Abstract: & & The discovery of long period comet C/2014 UN271 (Bernardinelli-Bernstein) announced in June 2021 quickly suggested an inactive nucleus with an absolute magnitude of H& sub& V& /sub& = 7.8 mag [1], which implied a diameter between 130 and 260 km assuming geometric albedos between 2% and 8%. Immediate follow-up observations with our Las Cumbres Observatory (LCO) Outbursting Objects Key project (LOOK) [2] as well as with SkyGems Namibia [3] revealed that the comet was active at 20.18 au. Evidence was quickly found that C/2014 UN271 had been active since 2018 and possibly even active at the time it was first observed in 2014 (at 29 au) [4,5]. After the discovery announcement, follow-up observations with ALMA and HST determined that Bernardinelli-Bernstein has a cometary albedo (0.033 & #177 0.009) and an effective diameter of 137 & #177 17 km, distinguishing it as the largest observed Oort-cloud comet [6,7].& & & & Prior to the observations of C/2014 UN271, the most distant comet discoveries were C/2010 U3 and C/2017 K2, which were made between 15 and 20 au, but for which pre-discovery images indicate activity beyond 20 au [8,9]. C/2014 UN271 was significantly brighter than those comets at the same distance, which provided an exceptional opportunity to characterize its very distant comet activity close to 20 au. In this presentation we will report the results of our observing program with FORS2 on ESO& #8217 s 8-meter VLT in July and August 2021. The VLT/FORS data are interpreted in combination with targeted observations with the 4.1-m SOAR and the long-term monitoring c aign with 1-m facilities within the LOOK Project [10,11].& & & & & The multi-facility long-term photometric monitoring of C/2014 UN271 enabled our team to identify three outbursts between June and September 2021, indicating that the comet's optical brightness was dominated by cometary outbursts during the VLT observing run. Our VLT/FORS2 multi-band imaging and spectroscopic observations allowed us therefore to characterize the comet& #8217 s outburst in terms of spectral slope and coma morphology, including arc-like features. We will also present our efforts to characterize the comet& #8217 s short-term variability and rotation period.& & & & & & & & & & & & em& References: [1] & /em& & em& ec/K21/K21M53.html& /em& & em& [2] Kokotanekova, R., et al. (2021), ATel, 14733 [3] & /em& & em& ec/K21/K21M83.html& /em& & em& [4] & /em& & em& ec/K21/K21M83.html& /em& & em& [5] Farnham, T. (2021), ATel, 14759& & /em& [6] Lellouch, E. et al. (2022) A& ,659, L1, 8 [7] & em& Hui, M.-T., et al. (2022) ApJL, 929, 1, L12, 7& & /em& & em& [8] Hui, M.-T., et al. (2019) AJ 157 [9] Jewitt, D. et al. (2021) AJ 161, 188 [10] Lister et al., submitted [11] Kelley et al., submitted.& /em& & & & & & br /& & br /& & &
Publisher: American Astronomical Society
Date: 23-05-2023
Abstract: The Vera C. Rubin Observatory is expected to start the Legacy Survey of Space and Time (LSST) in early to mid-2025. This multiband wide-field synoptic survey will transform our view of the solar system, with the discovery and monitoring of over five million small bodies. The final survey strategy chosen for LSST has direct implications on the discoverability and characterization of solar system minor planets and passing interstellar objects. Creating an inventory of the solar system is one of the four main LSST science drivers. The LSST observing cadence is a complex optimization problem that must balance the priorities and needs of all the key LSST science areas. To design the best LSST survey strategy, a series of operation simulations using the Rubin Observatory scheduler have been generated to explore the various options for tuning observing parameters and prioritizations. We explore the impact of the various simulated LSST observing strategies on studying the solar system’s small body reservoirs. We examine what are the best observing scenarios and review what are the important considerations for maximizing LSST solar system science. In general, most of the LSST cadence simulations produce ±5% or less variations in our chosen key metrics, but a subset of the simulations significantly hinder science returns with much larger losses in the discovery and light-curve metrics.
Publisher: American Astronomical Society
Date: 23-11-2015
Publisher: Springer Science and Business Media LLC
Date: 18-12-2017
Publisher: American Astronomical Society
Date: 23-05-2016
Publisher: American Astronomical Society
Date: 18-08-2017
Publisher: American Astronomical Society
Date: 07-2022
DOI: 10.3847/PSJ/AC7A31
Abstract: The LCO Outbursting Objects Key (LOOK) Project uses the telescopes of the Las Cumbres Observatory (LCO) Network to (1) systematically monitor a s le of previously discovered over the whole sky, to assess the evolutionary state of these distant remnants from the early solar system, and (2) use alerts from existing sky surveys to rapidly respond to and characterize detected outburst activity in all small bodies. The data gathered on outbursts helps to characterize each outburst’s evolution with time, helps to assess the frequency and magnitude distribution of outbursts in general, and contributes to the understanding of outburst processes and volatile distribution in the solar system. The LOOK Project exploits the synergy between current and future wide-field surveys such as ZTF, Pan-STARRS, and LSST, as well as rapid-response telescope networks such as LCO, and serves as an excellent test bed for what will be needed for the much larger number of objects coming from Rubin Observatory. We will describe the LOOK Project goals, the planning and target selection (including the use of NEOexchange as a Target and Observation Manager or “TOM”), and results from the first phase of observations, including the detection of activity and outbursts on the giant comet C/2014 UN 271 (Bernardinelli–Bernstein) and the discovery and follow-up of 28 outbursts on 14 comets. Within these outburst discoveries, we present a high-cadence light curve of 7P/Pons–Winnecke with 10 outbursts observed over 90 days, a large outburst on 57P/duToit–Neujmin–Delporte, and evidence that comet P/2020 X1 (ATLAS) was in outburst when discovered.
Publisher: Springer Science and Business Media LLC
Date: 09-02-2018
Publisher: EDP Sciences
Date: 25-10-2012
Publisher: American Astronomical Society
Date: 22-03-2016
Publisher: American Astronomical Society
Date: 28-06-2016
Publisher: American Astronomical Society
Date: 06-07-2012
Publisher: Proceedings of the National Academy of Sciences
Date: 05-07-2000
Abstract: Transforming growth factor β (TGF-β) has been shown to participate in the pathophysiology of diabetic complications. As shown most recently, TGF-β stimulates the expression of a distinct serine/threonine kinase (hSGK) which had previously been cloned as an early gene transcriptionally regulated by cell volume alterations. The present study was performed to elucidate transcription and function of hSGK in diabetic nephropathy. As shown by Northern blotting, an increase of extracellular glucose concentration increased hSGK mRNA levels in cultured cells, an effect qualitatively mimicked by osmotic cell shrinkage or treatment with TGF-β (2 μg/liter), phorbol 12,13-didecanoate (1 μM), or the Ca 2+ ionophore ionomycin (1 μM) and blunted by high concentrations of nifedipine (10 and 100 μM). In situ hybridization revealed that hSGK transcription was markedly enhanced in diabetic nephropathy, with particularly high expression in mesangial cells, interstitial cells, and cells in thick ascending limbs of Henle's loop and distal tubules. According to voltage cl and tracer flux studies in Xenopus oocytes expressing the renal epithelial Na + channel ENaC or the mouse thick ascending limb Na + ,K + ,2Cl − cotransporter BSC-1, coexpression with hSGK stimulated ENaC and BSC-1 11-fold and 6-fold, respectively, effects reversed by kinase inhibitors staurosporine (1 μM) and chelerythrine (1 μM) and not elicited by inactive hSGK. In conclusion, excessive extracellular glucose concentrations enhance hSGK transcription, which in turn stimulates renal tubular Na + transport. These observations disclose an additional element in the pathophysiology of diabetic nephropathy.
Publisher: American Astronomical Society
Date: 07-11-2016
Publisher: American Astronomical Society
Date: 16-10-2015
Publisher: American Astronomical Society
Date: 29-08-2016
Publisher: American Physiological Society
Date: 10-2008
DOI: 10.1152/AJPRENAL.90278.2008
Abstract: The heat shock protein subfamily of 90 kDa (HSP90) is composed of five isoforms. The more abundant proteins of this subfamily are cytosolic isoforms known as HSP90α and HSP90β. More than 100 client proteins have been found to be regulated by HSP90. Several studies have shown that HSP90 regulates nitric oxide synthesis that is dependent on endothelial nitric oxide synthase (eNOS). Because eNOS regulates renal vascular tone and glomerular filtration rate (GFR), the present study was designed to evaluate the effect of acute HSP90 inhibition with radicicol on GFR and the eNOS pathway. Twenty male Wistar rats were ided into two groups: control vehicle animals and radicicol-infused animals (25 μg·ml −1 ·min −1 ). Basal levels were taken before experimental measurements. Mean arterial pressure and renal blood flow (RBF) were recorded, as well as GFR, urinary nitrite and nitrate excretion (UNO 2 /NO 3 V). Additionally, we evaluated eNOS expression, Ser1177 and Thr495 eNOS phosphorylation levels, the eNOS dimer-to-monomer ratio, as well as oxidative stress by assessing renal lipoperoxidation and urinary isoprostane F 2α and hydrogen peroxide. HSP90 inhibition with radicicol produced a fall in RBF and GFR that was associated with a significant reduction of UNO 2 /NO 3 V. The effects of radicicol were in part mediated by a significant decrease in eNOS phosphorylation and in the eNOS dimer-to-monomer ratio. Our findings suggest that GFR is in part maintained by HSP90-eNOS interaction.
Publisher: Oxford University Press (OUP)
Date: 29-01-2019
DOI: 10.1093/MNRAS/STZ306
Publisher: IOP Publishing
Date: 25-10-2016
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: Mexico
No related grants have been discovered for Gerardo Gamba.