114 research outputs found
SAGE 3: A visible wavelength limb sounder
A brief description is presented for the SAGE 3 (Stratospheric Aerosol and Gas Experiment 3) instrument that has been selected to fly onboard the National Polar Platform 1 (NPOP 1) for the Earth Observational System (Eos) in 1996. The SAGE 3 instrument will perform earth limb sounding with the solar occultation technique measuring the ultraviolet (UV), the visible, and the near infrared (IR) wavelength solar radiation. The instrument will produce atmospheric data for the vertical distribution of aerosol, ozone, nitrogen dioxide, water vapor, and oxygen. The details of the instrument design, data flow, and processing requirements are discussed
Conformational photoswitching of a synthetic peptide foldamer bound within a phospholipid bilayer
The dynamic properties of foldamers, synthetic molecules that mimic folded biomolecules, have mainly been explored in free solution.We report on the design, synthesis, and conformational behavior of photoresponsive foldamers bound in a phospholipid bilayer akin to a biological membrane phase. These molecules contain a chromophore, which can be switched between two configurations by different wavelengths of light, attached to a helical synthetic peptide that both promotes membrane insertion and communicates conformational change along its length. Light-induced structural changes in the chromophore are translated into global conformational changes, which are detected by monitoring the solid-state 19 F nuclear magnetic resonance signals of a remote fluorine-containing residue located 1 to 2 nanometers away. The behavior of the foldamers in the membrane phase is similar to that of analogous compounds in organic solvents
Therapeutic and educational objectives in robot assisted play for children with autism
âThis material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder." âCopyright IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.â DOI: 10.1109/ROMAN.2009.5326251This article is a methodological paper that describes the therapeutic and educational objectives that were identified during the design process of a robot aimed at robot assisted play. The work described in this paper is part of the IROMEC project (Interactive Robotic Social Mediators as Companions) that recognizes the important role of play in child development and targets children who are prevented from or inhibited in playing. The project investigates the role of an interactive, autonomous robotic toy in therapy and education for children with special needs. This paper specifically addresses the therapeutic and educational objectives related to children with autism. In recent years, robots have already been used to teach basic social interaction skills to children with autism. The added value of the IROMEC robot is that play scenarios have been developed taking children's specific strengths and needs into consideration and covering a wide range of objectives in children's development areas (sensory, communicational and interaction, motor, cognitive and social and emotional). The paper describes children's developmental areas and illustrates how different experiences and interactions with the IROMEC robot are designed to target objectives in these areas.Final Published versio
Trend and variability in ozone in the tropical lower stratosphere over 2.5 solar cycles observed by SAGE II and OSIRIS
We have extended the satellite-based ozone anomaly time series to the
present (December 2012) by merging SAGE II (Stratospheric Aerosol and Gas Experiment
II) with OSIRIS (Optical Spectrograph and Infrared Imager System)
and correcting for the small bias (~0.5%) between them,
determined using their temporal overlap of 4 years. Analysis of the merged
data set (1984â2012) shows a statistically significant negative trend at all
altitudes in the 18â25 km range, including a trend of (â4.6 ± 2.6)% decade<sup>â1</sup>
at 19.5 km where the relative standard error is a minimum. We are
also able to replicate previously reported decadal trends in the tropical
lower-stratospheric ozone anomaly based on SAGE II observations.
Uncertainties are smaller on the merged trend than the SAGE II trend at all
altitudes. Underlying strong fluctuations in ozone anomaly due to El NiñoâSouthern Oscillation (ENSO), the altitude-dependent quasi-biennial
oscillation, and tropopause pressure need to be taken into account to reduce
trend uncertainties and, in the case of ENSO, to accurately determine the
linear trend just above the tropopause. We also compare the observed ozone
trend with a calculated trend that uses information on tropical upwelling
and its temporal trend from model simulations, tropopause pressure trend
information derived from reanalysis data, and vertical profiles from SAGE II
and OSIRIS to determine the vertical gradient of ozone and its trend. We
show that the observed trend agrees with the calculated trend and that the
magnitude of the calculated trend is dominated by increased tropical
upwelling, with minor but increasing contribution from the vertical ozone
gradient trend as the tropical tropopause is approached. Improvements are
suggested for future regression modelling efforts which could reduce trend
uncertainties and biases in trend magnitudes, thereby allowing accurate
trend detection to extend below 18 km
SAGE Version 7.0 Algorithm: Application to SAGE II
This paper details the Stratospheric Aerosol and Gas Experiments (SAGE) version 7.0 algorithm and how it is applied to SAGE II. Changes made between the previous (v6.2) and current (v7.0) versions are described and their impacts on the data products explained for both coincident event comparisons and time-series analysis. Users of the data will notice a general improvement in all of the SAGE II data products, which are now in better agreement with more modern data sets (e.g. SAGE III) and more robust for use with trend studies
Global and long-term comparison of SCIAMACHY limb ozone profiles with correlative satellite data (2002â2008)
SCIAMACHY limb scatter ozone profiles from 2002 to 2008 have been compared with MLS (2005â2008), SABER (2002â2008), SAGE II (2002â2005), HALOE (2002â2005) and ACE-FTS (2004â2008) measurements. The comparison is performed for global zonal averages and heights from 10 to 50 km in one km steps. The validation was performed by comparing monthly mean zonal means and by comparing averages over collocated profiles within a zonal band and month. Both approaches yield similar results. For most of the stratosphere SCIAMACHY agrees to within 10% or better with other correlative data. A systematic bias of SCIAMACHY ozone of up to 100% between 10 and 20 km in the tropics points to some remaining issues with regard to convective cloud interference. Statistical hypothesis testing reveals at which altitudes and in which region differences between SCIAMACHY and other satellite data are statistically significant. We also estimated linear trends from monthly mean data for different periods where SCIAMACHY has common observations with other satellite data using a classical trend model with QBO and seasonal terms in order to draw conclusions on potential instrumental drifts as a function of latitude and altitude. Since the time periods considered here are rather short these trend estimates are only used to identify potential instrumental issues with the SCIAMACHY data. As a result SCIAMACHY exhibits a statistically significant negative trend in the range of of about 1â3% per year depending on latitude during the period 2002â2005 (overlapping with HALOE and SAGE II) and somewhat less during 2002â2008 (overlapping with SABER) in the altitude range of 30â40 km, while in the period 2004â2008 (overlapping with MLS and ACE-FTS) no significant trends are observed. Since all correlative satellite instruments do not show to a very large extent statistically significant trends in any of the time periods considered here, the negative trends observed with SCIAMACHY data point at some remaining instrumental artifact which is most likely related to residual errors in the tangent height registration of SCIAMACHY
Merged SAGEÂ II, Ozone_cci and OMPS ozone profile dataset and evaluation of ozone trends in the stratosphere
In this paper, we present a merged dataset of ozone profiles from
several satellite instruments: SAGEÂ II on ERBS, GOMOS, SCIAMACHY and
MIPAS on Envisat, OSIRIS on Odin, ACE-FTS on SCISAT, and OMPS on
Suomi-NPP. The merged dataset is created in the framework of the
European Space Agency Climate Change Initiative (Ozone_cci) with
the aim of analyzing stratospheric ozone trends. For the merged
dataset, we used the latest versions of the original ozone
datasets. The datasets from the individual instruments have been
extensively validated and intercompared; only those datasets which
are in good agreement, and do not exhibit significant drifts with
respect to collocated ground-based observations and with respect to
each other, are used for merging. The long-term SAGEâCCIâOMPS
dataset is created by computation and merging of deseasonalized
anomalies from individual instruments.
The merged SAGEâCCIâOMPS dataset consists of deseasonalized
anomalies of ozone in 10° latitude bands from 90°âŻS
to 90°âŻN and from 10 to 50âŻkm in steps of
1âŻkm covering the period from October 1984 to
July 2016. This newly created dataset is used for evaluating ozone
trends in the stratosphere through multiple linear
regression. Negative ozone trends in the upper stratosphere are
observed before 1997 and positive trends are found after 1997. The
upper stratospheric trends are statistically significant at
midlatitudes and indicate ozone recovery, as expected from the
decrease of stratospheric halogens that started in the middle of the
1990s and stratospheric cooling
Low Energy Nuclear Reaction Aircraft- 2013 ARMD Seedling Fund Phase I Project
This report serves as the final written documentation for the Aeronautic Research Mission Directorate (ARMD) Seedling Fund's Low Energy Nuclear Reaction (LENR) Aircraft Phase I project. The findings presented include propulsion system concepts, synergistic missions, and aircraft concepts. LENR is a form of nuclear energy that potentially has over 4,000 times the energy density of chemical energy sources. It is not expected to have any harmful emissions or radiation which makes it extremely appealing. There is a lot of interest in LENR, but there are no proven theories. This report does not explore the feasibility of LENR. Instead, it assumes that a working system is available. A design space exploration shows that LENR can enable long range and high speed missions. Six propulsion concepts, six missions, and four aircraft concepts are presented. This report also includes discussion of several issues and concerns that were uncovered during the study and potential research areas to infuse LENR aircraft into NASA's aeronautics research
Long-term evolution of upper stratospheric ozone at selected stations of the Network for the Detection of Stratospheric Change (NDSC)
The long-term evolution of upper stratospheric ozone has been recorded by lidars and
microwave radiometers within the ground-based Network for the Detection of
Stratospheric Change (NDSC), and by the space-borne Solar Backscatter Ultra-Violet
instruments (SBUV), Stratospheric Aerosol and Gas Experiment (SAGE), and Halogen
Occultation Experiment (HALOE). Climatological mean differences between these
instruments are typically smaller than 5% between 25 and 50 km. Ozone anomaly time
series from all instruments, averaged from 35 to 45 km altitude, track each other very
well and typically agree within 3 to 5%. SBUV seems to have a slight positive drift against
the other instruments. The corresponding 1979 to 1999 period from a transient simulation
by the fully coupled MAECHAM4-CHEM chemistry climate model reproduces many
features of the observed anomalies. However, in the upper stratosphere the model shows
too low ozone values and too negative ozone trends, probably due to an underestimation of
methane and a consequent overestimation of ClO. The combination of all observational
data sets provides a very consistent picture, with a long-term stability of 2% or better.
Upper stratospheric ozone shows three main features: (1) a decline by 10 to 15% since
1980, due to chemical destruction by chlorine; (2) two to three year fluctuations by 5 to
10%, due to the Quasi-Biennial Oscillation (QBO); (3) an 11-year oscillation by about
5%, due to the 11-year solar cycle. The 1979 to 1997 ozone trends are larger at the southern
mid-latitude station Lauder (45 S), reaching 8%/decade, compared to only about
6%/decade at Table Mountain (35 N), Haute Provence/Bordeaux ( 45 N), and
Hohenpeissenberg/Bern( 47 N). At Lauder, Hawaii (20 N), Table Mountain, and Haute
Provence, ozone residuals after subtraction of QBO- and solar cycle effects have levelled
off in recent years, or are even increasing. Assuming a turning point in January 1997,
the change of trend is largest at southern mid-latitude Lauder, +11%/decade, compared to
+7%/decade at northern mid-latitudes. This points to a beginning recovery of upper
stratospheric ozone. However, chlorine levels are still very high and ozone will remain
vulnerable. At this point the most northerly mid-latitude station, Hohenpeissenberg/Bern
differs from the other stations, and shows much less clear evidence for a beginning
recovery, with a change of trend in 1997 by only +3%/decade. In fact, record low upper
stratospheric ozone values were observed at Hohenpeissenberg/Bern, and to a lesser degree
at Table Mountain and Haute Provence, in the winters 2003/2004 and 2004/2005
Ground-Based Assessment of the Bias and Long-Term Stability of Fourteen Limb and Occultation Ozone Profile Data Records
The ozone profile records of a large number of limb and occultation satellite instruments are widely used to address several key questions in ozone research. Further progress in some domains depends on a more detailed understanding of these data sets, especially of their long-term stability and their mutual consistency. To this end, we made a systematic assessment of fourteen limb and occultation sounders that, together, provide more than three decades of global ozone profile measurements. In particular, we considered the latest operational Level-2 records by SAGE II, SAGE III, HALOE, UARS MLS, Aura MLS, POAM II, POAM III, OSIRIS, SMR, GOMOS, MIPAS, SCIAMACHY, ACE-FTS and MAESTRO. Central to our work is a consistent and robust analysis of the comparisons against the ground-based ozonesonde and stratospheric ozone lidar networks. It allowed us to investigate, from the troposphere up to the stratopause, the following main aspects of satellite data quality: long-term stability, overall bias, and short-term variability, together with their dependence on geophysical parameters and profile representation. In addition, it permitted us to quantify the overall consistency between the ozone profilers. Generally, we found that between 20-40 kilometers the satellite ozone measurement biases are smaller than plus or minus 5 percent, the short-term variabilities are less than 5-12 percent and the drifts are at most plus or minus 5 percent per decade (or even plus or minus 3 percent per decade for a few records). The agreement with ground-based data degrades somewhat towards the stratopause and especially towards the tropopause where natural variability and low ozone abundances impede a more precise analysis. In part of the stratosphere a few records deviate from the preceding general conclusions; we identified biases of 10 percent and more (POAM II and SCIAMACHY), markedly higher single-profile variability (SMR and SCIAMACHY), and significant long-term drifts (SCIAMACHY, OSIRIS, HALOE, and possibly GOMOS and SMR as well). Furthermore, we reflected on the repercussions of our findings for the construction, analysis and interpretation of merged data records. Most notably, the discrepancies between several recent ozone profile trend assessments can be mostly explained by instrumental drift. This clearly demonstrates the need for systematic comprehensive multi-instrument comparison analyses
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