703 research outputs found
Jet transport performance in thunderstorm wind shear conditions
Several hours of three dimensional wind data were collected in the thunderstorm approach-to-landing environment, using an instrumented Queen Air airplane. These data were used as input to a numerical simulation of aircraft response, concentrating on fixed-stick assumptions, while the aircraft simulated an instrument landing systems approach. Output included airspeed, vertical displacement, pitch angle, and a special approach deterioration parameter. Theory and the results of approximately 1000 simulations indicated that about 20 percent of the cases contained serious wind shear conditions capable of causing a critical deterioration of the approach. In particular, the presence of high energy at the airplane's phugoid frequency was found to have a deleterious effect on approach quality. Oscillations of the horizontal wind at the phugoid frequency were found to have a more serious effect than vertical wind. A simulation of Eastern flight 66, which crashed at JFK in 1975, served to illustrate the points of the research. A concept of a real-time wind shear detector was outlined utilizing these results
Safety and Efficacy of Extended Interval Dosing for Immune Checkpoint Inhibitors in Non-Small Cell Lung Cancer During the COVID-19 Pandemic
INTRODUCTION: Extended interval (EI) dosing for immune checkpoint inhibitor (ICI) mono- or consolidation therapy initiated due to the COVID-19 pandemic led to a significant reduction in ICI-related site visits for patients with stage III and IV non-small cell lung cancer (NSCLC). Here we report the safety and efficacy compared to standard dose (SD) schedules. METHOD: In this retrospective analysis patients who received ICI mono- or consolidation therapy, or adjuvant ICI therapy were assessed. Safety and efficacy of EI dosing with data of SD schedules were compared. RESULTS: One hundred seventeen patients received EI dosing for ICI and 88 patients SD. Patient characteristics were comparable. We observed 237 adverse events in the EI dosing cohort versus 118 in the SD group (p = 0.02). Overall, there was no difference in the occurrence of grade ≥3 adverse events (EI dosing: 21/237 [8.9%]; SD group: 20/118 [17.0%], p = 0.42), except for the pembrolizumab EI dosing cohort. Of all patients who received an EI dosing schedule, however, only 8 (6.8%) were reduced to SD because of toxicity. In 5 (4.3%) patients ICI was permanently stopped because of severe toxicity compared to 11 (12.5%) discontinuations in the SD group. Short-term treatment interruption occurred with similar frequencies in both groups. PFS and OS were comparable in patients receiving pembrolizumab and in those receiving adjuvant durvalumab. Progression-free survival and OS were better in the EI dosing cohort of nivolumab. CONCLUSION: EI dosing for ICI did not lead to an increase of clinically relevant toxicities resulting in dose reduction and/or treatment discontinuation. Efficacy of EI dosing of pembrolizumab and durvalumab were comparable to SD. Based on our safety and efficacy data EI dosing for ICI seems a safe and effective strategy. MICRO ABSTRACT: Aim Retrospective analysis of the safety and efficacy of extended interval dosing (EI) ICI compared to standard dose (SD) schedules. Results 117 patients received EI dosing and 88 SD. In the EI dosing cohort was no increase in toxicity leading to dose reduction and/or discontinuation of treatment. Furthermore, efficacy of EI dosing of pembrolizumab and durvalumab were comparable to SD. Based on our safety and efficacy data EI dosing for ICI seem a safe and effective strategy and should be continued also beyond the COVID-19 pandemic
Blunt cerebrovascular injuries in the craniofacial fracture population - Are we screening the right patients?
Current knowledge of blunt cerebrovascular injuries (BCVIs) in craniomaxillofacial fracture (CMF) patients is limited. The purpose of this study was to determine the occurrence of BCVIs in patients with all types of CMF. This retrospective study included CMF patients in a level 1 trauma centre during a 3-year period. Patients who were not imaged with computed tomography angiography and patients with mechanisms other than blunt injury were excluded. The primary outcome variable was BCVI. A total of 753 patients were included in the analysis. A BCVI was detected in 4.4% of the patients screened. BCVIs occurred in 8.7% of cranial fracture patients, 7.1% of combined craniofacial fracture patients, and 3.1% of facial fracture patients. The risk of BCVI was significantly increased in patients with isolated cranial fractures (odds ratio (OR) 2.55, 95% confidence interval (CI) 1.18?5.50; P = 0.017), those involved in motor vehicle accidents (OR 3.42, 95% CI 1.63?7.17; P = 0.001), and those sustaining high-energy injuries (OR 3.17, 95% CI 1.57?6.40; P = 0.001). BCVIs in CMF patients are relatively common in highenergy injuries. However, these injuries also occur in minor traumas. Imaging thresholds should be kept low in this patient population when BCVIs are suspected.Peer reviewe
Submillimeter Wave Astronomy Satellite observations of comet 9P/Tempel 1 and Deep Impact
On 4 July 2005 at 5:52 UT the Deep Impact mission successfully completed its
goal to hit the nucleus of 9P/Tempel 1 with an impactor, forming a crater on
the nucleus and ejecting material into the coma of the comet. NASA's
Submillimeter Wave Astronomy Satellite (SWAS) observed the 1(10)-1(01)
ortho-water ground-state rotational transition in comet 9P/Tempel 1 before,
during, and after the impact. No excess emission from the impact was detected
by SWAS and we derive an upper limit of 1.8e7 kg on the water ice evaporated by
the impact. However, the water production rate of the comet showed large
natural variations of more than a factor of three during the weeks before and
after the impact. Episodes of increased activity with Q(H2O)~1e28 molecule/s
alternated with periods with low outgassing (Q(H2O)<~5e27 molecule/s). We
estimate that 9P/Tempel 1 vaporized a total of N~4.5e34 water molecules (~1.3e9
kg) during June-September 2005. Our observations indicate that only a small
fraction of the nucleus of Tempel 1 appears to be covered with active areas.
Water vapor is expected to emanate predominantly from topographic features
periodically facing the Sun as the comet rotates. We calculate that appreciable
asymmetries of these features could lead to a spin-down or spin-up of the
nucleus at observable rates.Comment: 38 pages, 2 tables, 7 figures; Icarus, in pres
Genetic and morphometric divergence of an invasive bird : the introduced house sparrow (Passer domesticus) in Brazil
Introduced species are interesting systems for the study of contemporary evolution in new environments because of their spatial and temporal scales. For this study we had three aims: (i) to determine how genetic diversity and genetic differentiation of introduced populations of the house sparrow (Passer domesticus) in Brazil varies with range expansion, (ii) to determine how genetic diversity and differentiation in Brazil compares to ancestral European populations; and (iii) to determine whether selection or genetic drift has been more influential on phenotypic divergence. We used six microsatellite markers to genotype six populations from Brazil and four populations from Europe. We found slightly reduced levels of genetic diversity in Brazilian compared to native European populations. However, among introduced populations of Brazil, we found no association between genetic diversity and time since introduction. Moreover, overall genetic differentiation among introduced populations was low indicating that the expansion took place from large populations in which genetic drift effects would likely have been weak. We found significant phenotypic divergence among sites in Brazil. Given the absence of a spatial genetic pattern, divergent selection and not genetic drift seems to be the main force behind most of the phenotypic divergence encountered. Unravelling whether microevolution (e.g., allele frequency change), phenotypic plasticity, or both mediated phenotypic divergence is challenging and will require experimental work (e.g., common garden experiments or breeding programs)
A Sample of [CII] Clouds Tracing Dense Clouds in Weak FUV Fields observed by Herschel
The [CII] fine--structure line at 158um is an excellent tracer of the warm
diffuse gas in the ISM and the interfaces between molecular clouds and their
surrounding atomic and ionized envelopes. Here we present the initial results
from Galactic Observations of Terahertz C+ (GOTC+), a Herschel Key Project
devoted to study the [CII] fine structure emission in the galactic plane using
the HIFI instrument. We use the [CII] emission together with observations of CO
as a probe to understand the effects of newly--formed stars on their
interstellar environment and characterize the physical and chemical state of
the star-forming gas. We collected data along 16 lines--of--sight passing near
star forming regions in the inner Galaxy near longitudes 330 degrees and 20
degrees. We identify fifty-eight [CII] components that are associated with
high--column density molecular clouds as traced by 13CO emission. We combine
[CII], 12CO, and 13CO observations to derive the physical conditions of the
[CII]--emitting regions in our sample of high--column density clouds based on
comparison with results from a grid of Photon Dominated Region (PDR) models.
From this unbiased sample, our results suggest that most of [CII] emission
originates from clouds with H2 volume densities between 10e3.5 and 10e5.5 cm^-3
and weak FUV strength (CHI_0=1-10). We find two regions where our analysis
suggests high densities >10e5 cm^-3 and strong FUV fields (CHI=10e4-10e6),
likely associated with massive star formation. We suggest that [CII] emission
in conjunction with CO isotopes is a good tool to differentiate between regions
of massive star formation (high densities/strong FUV fields) and regions that
are distant from massive stars (lower densities/weaker FUV fields) along the
line--of--sightComment: To be published in A&A HIFI Special Editio
The structure of self-gravitating clouds
To study the interaction of star-formation and turbulent molecular cloud
structuring, we analyse numerical models and observations of self-gravitating
clouds using the Delta-variance as statistical measure for structural
characteristics. In the models we resolve the transition from purely
hydrodynamic turbulence to gravitational collapse associated with the formation
and mass growth of protostellar cores. We compare models of driven and freely
decaying turbulence with and without magnetic fields. Self-gravitating
supersonic turbulence always produces a density structure that contains most
power on the smallest scales provided by collapsed cores as soon as local
collapse sets in. This is in contrast to non-self-gravitating hydrodynamic
turbulence where the Delta-variance is dominated by large scale structures. To
detect this effect in star-forming regions observations have to resolve the
high density contrast of protostellar cores with respect to their ambient
molecular cloud. Using the 3mm continuum map of a star-forming cluster in
Serpens we show that the dust emission traces the full density evolution. On
the contrary, the density range accessible by molecular line observations is
insufficient for this analysis. Only dust emission and dust extinction
observations are able to to determine the structural parameters of star-forming
clouds following the density evolution during the gravitational collapse.Comment: 12 pages, 9 figures, A&A in pres
Probing isotopic ratios at z = 0.89: molecular line absorption in front of the quasar PKS 1830-211
With the Plateau de Bure interferometer, we have measured the C, N, O and S
isotopic abundance ratios in the arm of a spiral galaxy with a redshift of
0.89. The galaxy is seen face-on according to HST images. Its bulge intercepts
the line of sight to the radio-loud quasar PKS 1830-211, giving rise at mm
wavelengths to two Einstein images located each behind a spiral arm. The arms
appear in absorption in the lines of several molecules, giving the opportunity
to study the chemical composition of a galaxy only a few Gyr old. The isotopic
ratios in this spiral galaxy differ markedly from those observed in the Milky
Way. The O/O and N/N ratios are low, as one would
expect from an object too young to let low mass stars play a major role in the
regeneration of the gas.Comment: accepted in A&
First-principles study of nucleation, growth, and interface structure of Fe/GaAs
We use density-functional theory to describe the initial stages of Fe film
growth on GaAs(001), focusing on the interplay between chemistry and magnetism
at the interface. Four features appear to be generic: (1) At submonolayer
coverages, a strong chemical interaction between Fe and substrate atoms leads
to substitutional adsorption and intermixing. (2) For films of several
monolayers and more, atomically abrupt interfaces are energetically favored.
(3) For Fe films over a range of thicknesses, both Ga- and As-adlayers
dramatically reduce the formation energies of the films, suggesting a
surfactant-like action. (4) During the first few monolayers of growth, Ga or As
atoms are likely to be liberated from the interface and diffuse to the Fe film
surface. Magnetism plays an important auxiliary role for these processes, even
in the dilute limit of atomic adsorption. Most of the films exhibit
ferromagnetic order even at half-monolayer coverage, while certain
adlayer-capped films show a slight preference for antiferromagnetic order.Comment: 11 two-column pages, 12 figures, to appear in Phys. Rev.
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