49,803 research outputs found
A new white dwarf companion around the Δμ star GJ 3346
No full textWe present the discovery of a white dwarf companion at ∼3.6″ from GJ 3346, a nearby (π ∼ 42 mas) K star observed with SPHERE@VLT as part of an open time survey for faint companions to objects with significant proper motion discrepancies (∆μ) between Gaia DR1 and Tycho-2. Syrius-like systems like GJ 3346 AB, which include a main sequence star and a white dwarf, can be difficult to detect because of the intrinsic faintness of the latter. They have, however, been found to be common contaminants for direct imaging searches. White dwarfs have in fact similar brightness to sub-stellar companions in the infrared, while being much brighter in the visible bands like those used by Gaia. Combining our observations with Gaia DR2 and with several additional archival data sets, we were able to fully constrain the physical properties of GJ 3346 B, such as its effective temperature (11× 103 ±500 K) as well as the cooling age of the system (648±58 Myrs). This allowed us to better understand the system history and to partially explains the discrepancies previously noted in the age indicators for this objects. Although further investigation is still needed, it seems that GJ 3346, which was previously classified as young, is in fact most likely to be older than 4 Gyrs. Finally, given that the mass (0.58 ± 0.01 M☉) and separation (85 au) of GJ 3346 B are compatible with the observed ∆μ, this discovery represents a further confirmation of the potential of this kind of dynamical signatures as selection methods for direct imaging surveys targeting faint, sub-stellar companions
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
Epidemiology and etiology of stroke in the young: new therapeutic perspectives for prevention
No full textCharacterising weather and rotation on substellar worlds
No full textPhotometric variability monitoring is sensitive to atmospheric inhomogeneities
as they rotate in and out of view, and is a key probe of atmospheric features in
brown dwarfs and giant exoplanets. The population of young, low-gravity brown
dwarfs are an excellent test bed for characterising the gravity dependence of brown
dwarf atmospheres while also providing a critical analogue to the population of
directly-imaged planets. This thesis aims to expand our current understanding of
the variability of brown dwarfs with a focus on the role of gravity on variability
properties. In Chapter 2 I present the detection of photometric variability in the
L7 planetary-mass object PSO 318.5-22, as well as subsequent multi-wavelength
ground-based and space-based monitoring. I use the followup observations to
measure the rotational period of PSO 318.5-22 and to investigate the horizontal
and vertical structure of its atmosphere. In Chapter 3 I supplement the existing
brown dwarf variability data in the literature with new rotational velocities to
reveal relations between inclination angle, variability amplitude and colour. These
new relations probe the latitudinal cloud structure of brown dwarfs for the first
time and will inform future searches for variability on both free-floating exoplanets
and directly-imaged companions. In Chapter 4 I present Spitzer monitoring of
the three lowest-mass members of the AB Doradus moving group. I report mid-IR
variability in two late-L exoplanet analogues, W0047 and 2M2244 and place upper
limits on the variability of the T5.5 planetary-mass object SDSS 1110. I measure
the rotational periods and inclination angles of W0047 and 2M2244 and find that
they are consistent with the relations reported in Chapter 3 for the field dwarf
sample. Finally, in Chapter 5 I present the first large survey for photometric
variability in young low-gravity brown dwarfs. Theory and observations have
shown that gravity plays an important role in the atmospheric properties of L
and T types objects. Surface gravity significantly affects the height at which
condensate clouds form in the atmosphere (Marley et al., 2012) and thus we can
expect that gravity will have an effect on variability. I detect variability in 6
low-gravity brown dwarfs, 4 of which are reported in this thesis for the first time.
Focusing on the L0-L8/5 objects in the survey, I find a variability occurrence
rate of 30+16/-8 %. I reanalyse the results of Radigan (2014) and find a variability
occurrence rate of 11+13/-4 % for the field dwarf sample. This is the first quantitative
indication that the young objects are more likely to be variable than their higher
mass counterparts. The work presented in this thesis has provided crucial insight
into the role of gravity on variability properties, and acts as a key pathfinder for
future studies of variability on directly-imaged planets
COVID-19 and Cushing's syndrome: recommendations for a special population with endogenous glucocorticoid excess
No full textOver the past few months, COVID-19, the pandemic
disease caused by severe acute respiratory syndrome
coronavirus 2, has been associated with a high rate
of infection and lethality, especially in patients with
comorbidities such as obesity, hypertension, diabetes,
and immunodeficiency syndromes.1
These cardiometabolic and immune impairments
are common comorbidities of Cushing’s syndrome,
a condition characterised by excessive exposure to
endogenous glucocorticoids. In patients with Cushing’s
syndrome, the increased cardiovascular risk factors,
amplified by the increased thromboembolic risk, and the
increased susceptibility to severe infections, are the two
leading causes of death
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Informal gold mining and mercury pollution in Brazil
No full textThe Amazon region has been responsible for a major share of Brazilian gold production in recent years. The region has witnessed a sizable gold rush comparable only to the California gold rush last century. The gold rush has spawned a powerful informal mining sector and has attracted many people - some who have come to the region in search of wealth and some who were already there but were displaced from other, unsuccessful economicactivities. What these people encounter at the mining sites are dreadful living and working conditions. Gold mining also causes substantial environmental problems, which may persist whether gold deposits do or not. The author discusses the environmental effects of gold mining in the region, focusing on mercury pollution. Mercury, an important input in gold extraction, is being discharged into the atmosphere and the rivers at alarming rates. The environmental costs of the present extraction, is being discharged into the atmosphere and the rivers at alarming rates. The environmental costs of the present extraction technology will be faced primarily by future generations, because of natural chemical processes. Although removing the mercury already discharged from the Amazonian environment may be an enormous task, at least future discharges should be curtailed through the use of appropriate technology, environmental education, and a combination of command and control measures and market-based incentives. The author describes the gold extraction process and the extent of mercury use and contamination. He analyzes key elements of the environmental problem, especially the informal miner and the fish economy. Finally, he suggests a combination of command and control regulations and market-based incentives adapted to the informal gold mining economic environment. He emphasizes the need for an education campaign about the perils of using mercury and the availability of more appropriate, and inexpensive, alternative extraction technologies.Mining&Extractive Industry (Non-Energy),Montreal Protocol,Water and Industry,Coastal and Marine Resources,Primary Metals
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Measurement of b-hadron masses
No full textMeasurements of b-hadron masses are performed with the exclusive decay modes B +→J/ψK +, B 0→J/ψK +, B0→J/ψKS0, Bs0→J/ψφ and Λb0→J/ψΛ using an integrated luminosity of 35pb -1 collected in pp collisions at a centre-of-mass energy of 7 TeV by the LHCb experiment. The momentum scale is calibrated with J/ψ→μ +μ - decays and verified to be known to a relative precision of 2 ×10 -4 using other two-body decays. The results are more precise than previous measurements, particularly in the case of the Bs0 and Λb0 masses
Levoketoconazole: a novel treatment for endogenous Cushing's syndrome
No full textIntroduction: Endogenous Cushing’s syndrome (CS) is a rare, life-threatening endocrine disorder that is caused by chronic exposure to cortisol overproduction. Levoketoconazole (Recorlev), a 2S, 4R stereoisomer of ketoconazole, is a steroidogenesis inhibitor under investigation for the treatment of CS. Areas covered: This review covers the pharmacology, efficacy, and safety of levoketoconazole for the treatment of patients with endogenous CS. Expert opinion: Based on the preclinical and clinical pharmacology findings, levoketoconazole appears to be the relevant enantiomer of ketoconazole for inhibition of steroidogenesis, with more potent inhibition of both cortisol and androgen synthesis relative to ketoconazole racemate and the 2R, 4S stereoisomer dextroketoconazole. Results from the phase III SONICS study showed that levoketoconazole was effective in normalizing cortisol levels and improving biomarkers of cardiovascular risk in a significant percentage of patients. In addition, treatment with levoketoconazole showed improvements in subjective clinical assessments of clinician-rated CS clinical signs and symptoms, patient-reported quality of life, and depression symptom severity. Testosterone levels decreased significantly in women. Levoketoconazole had an acceptable safety profile with no unexpected safety signals. The favorable pharmacology, efficacy, and safety profile of levoketoconazole supports its use as medical therapy for CS, if approved
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