392 research outputs found
Delivery of Dark Material to Vesta via Carbonaceous Chondritic Impacts
NASA's Dawn spacecraft observations of asteroid (4) Vesta reveal a surface
with the highest albedo and color variation of any asteroid we have observed so
far. Terrains rich in low albedo dark material (DM) have been identified using
Dawn Framing Camera (FC) 0.75 {\mu}m filter images in several geologic
settings: associated with impact craters (in the ejecta blanket material and/or
on the crater walls and rims); as flow-like deposits or rays commonly
associated with topographic highs; and as dark spots (likely secondary impacts)
nearby impact craters. This DM could be a relic of ancient volcanic activity or
exogenic in origin. We report that the majority of the spectra of DM are
similar to carbonaceous chondrite meteorites mixed with materials indigenous to
Vesta. Using high-resolution seven color images we compared DM color properties
(albedo, band depth) with laboratory measurements of possible analog materials.
Band depth and albedo of DM are identical to those of carbonaceous chondrite
xenolith-rich howardite Mt. Pratt (PRA) 04401. Laboratory mixtures of Murchison
CM2 carbonaceous chondrite and basaltic eucrite Millbillillie also show band
depth and albedo affinity to DM. Modeling of carbonaceous chondrite abundance
in DM (1-6 vol%) is consistent with howardite meteorites. We find no evidence
for large-scale volcanism (exposed dikes/pyroclastic falls) as the source of
DM. Our modeling efforts using impact crater scaling laws and numerical models
of ejecta reaccretion suggest the delivery and emplacement of this DM on Vesta
during the formation of the ~400 km Veneneia basin by a low-velocity (<2
km/sec) carbonaceous impactor. This discovery is important because it
strengthens the long-held idea that primitive bodies are the source of carbon
and probably volatiles in the early Solar System.Comment: Icarus (Accepted) Pages: 58 Figures: 15 Tables:
Phenomenology of the Lense-Thirring effect in the Solar System
Recent years have seen increasing efforts to directly measure some aspects of
the general relativistic gravitomagnetic interaction in several astronomical
scenarios in the solar system. After briefly overviewing the concept of
gravitomagnetism from a theoretical point of view, we review the performed or
proposed attempts to detect the Lense-Thirring effect affecting the orbital
motions of natural and artificial bodies in the gravitational fields of the
Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of
the impact of several sources of systematic uncertainties of dynamical origin
to realistically elucidate the present and future perspectives in directly
measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in
Astrophysics and Space Science (ApSS). Some uncited references in the text
now correctly quoted. One reference added. A footnote adde
Marital Satisfaction and Depression: A Replication of the Marital Discord Model in a Latino Sample
Efficacy and safety of dupilumab with concomitant topical corticosteroids in children 6 to 11 years old with severe atopic dermatitis: a randomized, double-blinded, placebo-controlled phase 3 trial
Background
Children with severe atopic dermatitis (AD) have limited treatment options.
Objective
We report efficacy and safety of dupilumab + topical corticosteroids (TCS) in children aged 6–11 years with severe AD inadequately controlled with topical therapies.
Methods
In this double-blind, 16-week, phase 3 trial (NCT03345914), 367 patients were randomized 1:1:1 to 300mg dupilumab every 4 weeks (300mg-q4w), a weight-based regimen of dupilumab every 2 weeks (100mg-q2w, baseline weight <30kg; 200mg-q2w, ≥30kg), or placebo; with concomitant medium-potency TCS.
Results
Both the q4w and q2w dupilumab+TCS regimens resulted in clinically meaningful and statistically significant improvement in signs, symptoms, and quality of life (QoL) versus placebo+TCS in all prespecified endpoints. For q4w/q2w/placebo, 32.8%/29.5%/11.4% of patients achieved Investigator’s Global Assessment scores of 0/1; 69.7%/67.2%/26.8% achieved ≥75% improvement in Eczema Area and Severity Index scores; and 50.8%/58.3%/12.3% achieved ≥4-point reduction in worst itch score. Response to therapy was weight-dependent: optimal dupilumab doses for efficacy and safety were 300mg-q4w in children <30kg and 200mg-q2w in children ≥30kg. Conjunctivitis and injection-site reactions were more common with dupilumab+TCS than placebo+TCS.
Limitations
Short-term 16-week treatment period; severe AD only.
Conclusion
Dupilumab+TCS is efficacious and well tolerated in children with severe AD, significantly improving signs, symptoms, and QoL
High Precision Measurement of the Proton Elastic Form Factor Ratio at low
We report a new, high-precision measurement of the proton elastic form factor
ratio \mu_p G_E/G_M for the four-momentum transfer squared Q^2 = 0.3-0.7
(GeV/c)^2. The measurement was performed at Jefferson Lab (JLab) in Hall A
using recoil polarimetry. With a total uncertainty of approximately 1%, the new
data clearly show that the deviation of the ratio \mu_p G_E/G_M from unity
observed in previous polarization measurements at high Q^2 continues down to
the lowest Q^2 value of this measurement. The updated global fit that includes
the new results yields an electric (magnetic) form factor roughly 2% smaller
(1% larger) than the previous global fit in this Q^2 range. We obtain new
extractions of the proton electric and magnetic radii, which are
^(1/2)=0.875+/-0.010 fm and ^(1/2)=0.867+/-0.020 fm. The charge
radius is consistent with other recent extractions based on the electron-proton
interaction, including the atomic hydrogen Lamb shift measurements, which
suggests a missing correction in the comparison of measurements of the proton
charge radius using electron probes and the recent extraction from the muonic
hydrogen Lamb shift.Comment: 12 pages, 3 figure
Physical Processes in Star Formation
© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00693-8.Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the physical processes at work, both individually and of their interactions. In this review we will give an overview of the main processes that are important for the understanding of star formation. We start with an observationally motivated view on star formation from a global perspective and outline the general paradigm of the life-cycle of molecular clouds, in which star formation is the key process to close the cycle. After that we focus on the thermal and chemical aspects in star forming regions, discuss turbulence and magnetic fields as well as gravitational forces. Finally, we review the most important stellar feedback mechanisms.Peer reviewedFinal Accepted Versio
Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV
Peer reviewe
Search for leptophobic Z ' bosons decaying into four-lepton final states in proton-proton collisions at root s=8 TeV
Peer reviewe
A search for resonances decaying into a Higgs boson and a new particle X in the XH → qqbb final state with the ATLAS detector
A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb−1 of proton–proton collision data at collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state is analysed. The search considers the regime of high XH resonance masses, where the X and H bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of XH mass versus X mass is scanned for evidence of a signal, over a range of XH resonance mass values between 1 TeV and 4 TeV, and for X particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of XH and X masses, on the production cross-section of the resonance
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