279 research outputs found
Electropneumatic linear gimbal actuation system, model nv-bi, 29 june 1963 - 29 june 1964
Electropneumatic linear actuator for thrust vector control on J- 2 rocket engin
Clear-column radiative closure during ACE-Asia: Comparison of multiwavelength extinction derived from particle size and composition with results from Sun photometry
From March to May 2001, aerosol size distributions and chemical compositions were measured using differential mobility analyzers (DMA), an aerodynamic particle sizer (APS), Micro-Orifice Uniform Deposit Impactors (MOUDI), and denuder samplers onboard the Twin Otter aircraft as part of the Aerosol Characterization Experiment (ACE)-Asia campaign. Of the 19 research flights, measurements on four flights that represented different aerosol characteristics are analyzed in detail. Clear-column radiative closure is studied by comparing aerosol extinctions predicted using in situ aerosol size distribution and chemical composition measurements to those derived from the 14-wavelength NASA Ames Airborne Tracking Sun photometer (AATS-14). In the boundary layer, pollution layers, and free troposphere with no significant mineral dust present, aerosol extinction closure was achieved within the estimated uncertainties over the full range of wavelengths of AATS-14. Aerosol extinctions predicted based on measured size distributions also reproduce the wavelength dependence derived from AATS-14 data. Considering all four flights, the best fit lines yield Predicted/Observed ratios in boundary and pollution layers of 0.97 ± 0.24 and 1.07 ± 0.08 at λ = 525 nm and 0.96 ± 0.21 and 1.08 ± 0.08 at λ = 1059 nm, respectively. In free troposphere dust layers, aerosol extinctions predicted from the measured size distributions were generally smaller than those derived from the AATS-14 data, with Predicted/Observed ratios of 0.65 ± 0.06 and 0.66 ± 0.05 at 525 and 1059 nm, respectively. A detailed analysis suggests that the discrepancy is likely a result of the lack of the knowledge of mineral dust shape as well as variations in aerosol extinction derived from AATS-14 data when viewing through horizontally inhomogeneous layers
In situ aerosol-size distributions and clear-column radiative closure during ACE-2
As part of the second Aerosol Characterization Experiment (ACE-2) during June and July of 1997, aerosol-size distributions were measured on board the CIRPAS Pelican aircraft through the use of a DMA and 2 OPCs. During the campaign, the boundary-layer aerosol typically possessed characteristics representative of a background marine aerosol or a continentally influenced aerosol, while the free-tropospheric aerosol was characterized by the presence or absence of a Saharan dust layer. A range of radiative closure comparisons were made using the data obtained during vertical profiles flown on 4 missions. Of particular interest here are the comparisons made between the optical properties as determined through the use of measured aerosol-size distributions and those measured directly by an airborne 14-wavelength sunphotometer and 3 nephelometers. Variations in the relative humidity associated with each of the direct measurements required consideration of the hygroscopic properties of the aerosol for size-distribution-based calculations. Simultaneous comparison with such a wide range of directly-measured optical parameters not only offers evidence of the validity of the physicochemical description of the aerosol when closure is achieved, but also provides insight into potential sources of error when some or all of the comparisons result in disagreement. Agreement between the derived and directly-measured optical properties varied for different measurements and for different cases. Averaged over the 4 case studies, the derived extinction coefficient at 525 nm exceeded that measured by the sunphotometer by 2.5% in the clean boundary layer, but underestimated measurements by 13% during pollution events. For measurements within the free troposphere, the mean derived extinction coefficient was 3.3% and 17% less than that measured by the sunphotometer during dusty and non-dusty conditions, respectively. Likewise, averaged discrepancies between the derived and measured scattering coefficient were −9.6%, +4.7%, +17%, and −41% for measurements within the clean boundary layer, polluted boundary layer, free troposphere with a dust layer, and free troposphere without a dust layer, respectively. Each of these quantities, as well as the majority of the >100 individual comparisons from which they were averaged, were within estimated uncertainties
Overview of ACE-Asia spring 2001 investigations on aerosol-radiation interactions
In spring 2001 the Asian Pacific Regional Aerosol
Characterization Experiment (ACE-Asia) made
extensive measurements from land, ocean, air and
space platforms. A primary objective was to
quantify the interactions between aerosols and
radiation. This talk presents illustrative results from
each type of platform, with initial assessments of
regional aerosol radiative forcing obtained by
combining satellite and suborbital results
Airborne sunphotometer, airborne in-situ, space-borne, and ground-based measurements of tropospheric aerosol in ACE-2
The North Atlantic Regional Aerosol Characterization
Experiment (ACE-2) of the International Global Atmospheric
Chemistry Project (IGAC) ran from 16 June to 25 July 1997.
The results presented in this study are part of the "Clear-sky
column closure experiment" (CLEARCOLUMN) activity,
one of 6 ACE-2 activities [1]. Clear-sky column closure
experiments call for characterization of aerosol layers by
simultaneous measurements using different techniques that
can be related using models [2].
A wide range of aerosol types was encountered throughout
the ACE-2 area, including background Atlantic marine,
European pollution-derived and African mineral dust. In a
series of papers, we reported on ACE-2 CLEARCOLUMN
results obtained by combining airborne sunphotometer and
in-situ measurements taken aboard the Pelican aircraft, spaceborne
NOAA/VHRR data and ground-based lidar and
sunphotometer measurements [3]-[10]. Those and other
CLEARCOLUMN results have been summarized in [11].
In this paper we only report on results not shown in this
form in [3]-[11]
Classification of the nucleolytic ribozymes based upon catalytic mechanism
The nucleolytic ribozymes carry out site-specific RNA cleavage reactions by nucleophilic attack of the 2’-oxygen atom on the adjacent phosphorus with an acceleration of a million-fold or greater. A major part of this arises from concerted general acid-base catalysis. Recent identification of new ribozymes has expanded the group to a total of nine and this provides a new opportunity to identify sub-groupings according to the nature of the general base and acid. These include nucleobases, hydrated metal ions, and 2’-hydroxyl groups. Evolution has selected a number of different combinations of these elements that lead to efficient catalysis. These differences provide a new mechanistic basis for classifying these ribozymes
mRNA Secondary Structures Fold Sequentially But Exchange Rapidly In Vivo
Self-cleavage assays of RNA folding reveal that mRNA structures fold sequentially in vitro and in vivo, but exchange between adjacent structures is much faster in vivo than it is in vitro
PF-05280014 (a trastuzumab biosimilar) plus paclitaxel compared with reference trastuzumab plus paclitaxel for HER2-positive metastatic breast cancer: a randomised, double-blind study
BACKGROUND: This randomised, double-blind study compared PF-05280014 (a trastuzumab biosimilar) with reference
trastuzumab (Herceptin®) sourced from the European Union (trastuzumab-EU), when each was given with paclitaxel as first-line
treatment for HER2-positive metastatic breast cancer.
METHODS: Between 4 April 2014 and 22 January 2016, 707 participants were randomised 1:1 to receive intravenous PF-05280014
plus paclitaxel (PF-05280014 group; n = 352) or trastuzumab-EU plus paclitaxel (trastuzumab-EU group; n = 355). PF-05280014 or
trastuzumab-EU was administered weekly (first dose 4 mg/kg, subsequent doses 2 mg/kg), with the option to change to a 3-weekly
regimen (6 mg/kg) from Week 33. Treatment with PF-05280014 or trastuzumab-EU could continue until disease progression.
Paclitaxel (starting dose 80 mg/m2
) was administered on Days 1, 8 and 15 of 28-day cycles for at least six cycles or until maximal
benefit of response. The primary endpoint was objective response rate (ORR), evaluating responses achieved by Week 25 and
confirmed by Week 33, based on blinded central radiology review.
RESULTS: The risk ratio for ORR was 0.940 (95% CI: 0.842–1.049). The 95% CI fell within the pre-specified equivalence margin of
0.80–1.25. ORR was 62.5% (95% CI: 57.2–67.6%) in the PF-05280014 group and 66.5% (95% CI: 61.3–71.4%) in the trastuzumab-EU
group. As of data cut-off on 11 January 2017 (using data up to 378 days post-randomisation), there were no notable differences
between groups in progression-free survival (median: 12.16 months in the PF-05280014 group vs. 12.06 months in the trastuzumab-EU
group; 1-year rate: 54% vs. 51%) or overall survival (median: not reached in either group; 1-year rate: 89.31% vs. 87.36%). Safety
outcomes and immunogenicity were similar between the treatment groups.
CONCLUSION: When given as first-line treatment for HER2-positive metastatic breast cancer, PF-05280014 plus paclitaxel
demonstrated equivalence to trastuzumab-EU plus paclitaxel in terms of ORR.
CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT0198967
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