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Ulsig L.,University of Edinburgh | Nichol C.J.,University of Edinburgh | Huemmrich K.F.,University of Maryland Baltimore County | Landis D.R.,Global Science and Technology | And 5 more authors.
Remote Sensing | Year: 2017

Long-term observations of vegetation phenology can be used to monitor the response of terrestrial ecosystems to climate change. Satellite remote sensing provides the most efficient means to observe phenological events through time series analysis of vegetation indices such as the Normalized Difference Vegetation Index (NDVI). This study investigates the potential of a Photochemical Reflectance Index (PRI), which has been linked to vegetation light use efficiency, to improve the accuracy of MODIS-based estimates of phenology in an evergreen conifer forest. Timings of the start and end of the growing season (SGS and EGS) were derived from a 13-year-long time series of PRI and NDVI based on a MAIAC (multi-angle implementation of atmospheric correction) processed MODIS dataset and standard MODIS NDVI product data. The derived dates were validated with phenology estimates from ground-based flux tower measurements of ecosystem productivity. Significant correlations were found between the MAIAC time series and ground-estimated SGS (R2 = 0.36-0.8), which is remarkable since previous studies have found it difficult to observe inter-annual phenological variations in evergreen vegetation from satellite data. The considerably noisier NDVI product could not accurately predict SGS, and EGS could not be derived successfully from any of the time series. While the strongest relationship overall was found between SGS derived from the ground data and PRI, MAIAC NDVI exhibited high correlations with SGS more consistently (R2 > 0.6 in all cases). The results suggest that PRI can serve as an effective indicator of spring seasonal transitions, however, additional work is necessary to confirm the relationships observed and to further explore the usefulness of MODIS PRI for detecting phenology. © 2017 by the authors; licensee MDPI, Basel, Switzerland.


Rauscher B.J.,Global Science and Technology | Antonille S.R.,Global Science and Technology | Boehm N.,Global Science and Technology | Davila P.S.,Conceptual Analytics LLC | And 10 more authors.
Publications of the Astronomical Society of the Pacific | Year: 2013

We describe the "overlight" test that was done for JWST's Teledyne H2RG HgCdTe near-infrared detector arrays. We projected many very bright λ = 632.8 nm spots onto one flight representative, substrate-removed, HgCdTe 5 μm cutoff detector array. We allowed individual spots to "burn in" for as long as ≈1000 s before turning off the laser. We did not detect any permanent change in detector performance for extreme over illuminations as bright as 320 μW pixel-1 (≤ 1 μW μm-2) after the array had been returned to ambient laboratory temperature and pressure. The brightest individual spot contained roughly 4 mW of power spread over a 100 μm diameter circular area. This is brighter than the brightest lasers that are planned for use during JWST integration and testing. It is also ≈103× brighter than any 632.8 nm astronomical source in the night sky. © 2013. The Astronomical Society of the Pacific. All rights reserved.


Hill R.J.,Conceptual Analytics Inc. | Malumuth E.,Wyle | Foltz R.,NASA | Kimble R.A.,NASA | And 5 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

The Detector Characterization Laboratory at NASA/GSFC has investigated the reciprocity failure characteristics of 1.7μm cut-off HgCdTe devices provided by Teledyne Imaging Sensors to the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) project. The reciprocity failure follows a power law behavior over the range of fluxes tested (0.1-10 4 photons/second). The slope of the power law varies among detectors, ranging from ~0.3-1%/dex at 1.0μm, which is much smaller than the ~6%/dex effect observed with the HST NICMOS 2.5μm cut-off detectors. In addition, the reciprocity failure exhibits no wavelength dependence, although only a restricted range of wavelengths (0.85-1.0μm) has been explored to date. Despite its relatively small magnitude, reciprocity failure is nevertheless an important effect in the calibration of WFC3 data, as well as in other applications in which there is a large difference in flux between the photometric standards and the scientific sources of interest. © 2010 SPIE.


Treatment with the Aerobika* device can significantly reduce the recurrence of exacerbations of COPD in the crucial 30-day period following hospitalization or emergency room visits, according to a study published this month in Pulmonary Therapy.[1] The study also showed that per-patient cost of exacerbations was significantly lower in the Aerobika* device group. This study provides the first real-world evidence for the benefits of using the Aerobika* device in reducing exacerbation-related emergency department visits and hospital readmissions. COPD is a major (and growing) source of morbidity, mortality and healthcare utilization, with hospitalization for acute exacerbations being the biggest cost driver. Once a patient experiences an exacerbation, the risk of further exacerbation is increased two- to four-fold[2], and many patients experience two or three exacerbations every year.[3]-[5] As many as one in five patients discharged from hospital following an exacerbation are re-admitted within 30 days.[6] This retrospective study analyzed hospital database records for 810 COPD Chronic Bronchitis patients who were hospitalized or visited the emergency room, and showed significantly fewer patients given the Aerobika* device experienced moderate-to-severe exacerbations or severe exacerbations compared with matched controls within the critical 30-day follow-up period. Exacerbation-related costs also showed a statistically significant savings in the Aerobika* device group compared with the control group for moderate-to severe and severe exacerbations. The Aerobika* device was given in addition to the patients' regular COPD treatments. "This is the first study to evaluate the benefits of any OPEP in a real-world setting, and it provides encouraging evidence that the Aerobika* device can help reduce recurrence of exacerbations in this high-risk group of patients over the crucial early 30-day period", noted Dr. Michael Bauer, Pulmonary Physician, Cooperstown, New York. Jason Suggett, PhD, BPharm, MRPharmS (Group Director of Global Science and Technology at TMI), explained how the Aerobika* device may provide these benefits. "During an exacerbation, airways are compromised by (among other factors) inflammation and mucus build-up, which can continue to disrupt ventilation mechanics and lung function after the event, and lead to prolonged respiratory impairment." He noted that "the Aerobika* device, with its proprietary mechanism of action, helps stent open and clear excess mucus from the upper airways, and may also aid drug deposition, providing a potential mechanism of protection from exacerbations". The internationally-recognized GOLD guidelines[7] stress the importance of exacerbation management, stating that a major treatment goal is to 'minimize the negative impact of the current exacerbation and to prevent subsequent events'. A recent analysis[2] predicting that the absolute number of COPD cases could increase by between 150% and 220% in the period from 2010 to 2030, with the burden of inpatient care (total annual inpatient days) growing by around 185% further underlines this need to address the burden of COPD exacerbations. A retrospective cohort study utilizing patient data from the US hospital Charge Detail Master (CDM) claims database (data selection period between 1 September 2013 and 31 August 2015). This real-word study involved 810 COPD patients with a diagnosis of chronic bronchitis, 405 receiving treatment with the Aerobika* device and 405 matched controls, (propensity matched to reduce bias and mimic randomization). The data showed significantly fewer patients given the Aerobika* device experienced moderate-to-severe exacerbations (18.5% vs 25.7%, p=0.014) or severe exacerbations (13.5% vs 19.0%; p<0.046) compared with matched controls over the 30-day follow-up period, with consequent reductions in costs. The Aerobika* device is hand-held, robust, easy-to-use, and drug-free with a proprietary mode of action. When the patient exhales through the device, intermittent resistance creates a unique pressure-oscillation dynamic, which expands the airways, helps expel the mucus to the upper airways where it can be coughed out, and may also aid in improved drug deposition. The Aerobika* device has been shown to significantly improve forced vital capacity (FVC), 6-min walk distance (6MWD), and St. George's Respiratory Questionnaire (SGRQ) score in COPD patients.[8] The Aerobika* device is available in Canada, Mexico (http://www.aerosolms.com ), Australia (http://www.airliquidehealthcare.com.au) and select European countries including the UK and Germany through Trudell Medical International and in the US via Monaghan Medical Corporation. TMI designs, develops and manufactures a wide range of high quality, innovative medical devices and is home to a global Aerosol Lab and Research Center. From the flagship AeroChamber* Brand of Valved Holding Chamber (VHC) and the latest award-winning Aerobika* device, to custom designed products and systems, our best-in-class respiratory management products have been sold in over 110 countries. Their efficacy has been validated in numerous peer-reviewed publications. For clinical inquiries, please contact: Dr. Jason Suggett, Group Director, Global Science and Technology, +1-519-455-7060 ext. 2270


Wald A.,Global Science and Technology | Levy R.C.,NASA | Angal A.,Science Systems And Applications Inc. | Geng X.,Science Systems And Applications Inc. | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

The spectral reflectance measured by the MODIS reflective solar bands (RSB) is used for retrieving many atmospheric science products. The accuracy of these products depends on the accuracy of the calibration of the RSB. To this end, the RSB of the MODIS instruments are primarily calibrated on-orbit using regular solar diffuser (SD) observations. For λ <0.94 μm the SD's on-orbit bi-directional reflectance factor (BRF) change is tracked using solar diffuser stability monitor (SDSM) observations. For λ <0.94 μm, the MODIS Characterization Support Team (MCST) developed, in MODIS Collection 6 (C6), a time-dependent correction using observations from pseudo-invariant earth-scene targets. This correction has been implemented in C6 for the Terra MODIS 1.24 μm band over the entire mission, and for the 1.38 μm band in the forward processing. As the instruments continue to operate beyond their design lifetime of six years, a similar correction is planned for other short-wave infrared (SWIR) bands as well. MODIS SWIR bands are used in deriving atmosphere products, including aerosol optical thickness, atmospheric total column water vapor, cloud fraction and cloud optical depth. The SD degradation correction in Terra bands 5 and 26 impact the spectral radiance and therefore the retrieval of these atmosphere products. Here, we describe the corrections to Bands 5 (1.24 μm) and 26 (1.38 μm), and produce three sets (B5, B26 correction = on/on, on/off, and off/off) of Terra-MODIS Level 1B (calibrated radiance product) data. By comparing products derived from these corrected and uncorrected Terra MODIS Level 1B (L1B) calibrations, dozens of L3 atmosphere products are surveyed for changes caused by the corrections, and representative results are presented. Aerosol and water vapor products show only small local changes, while some cloud products can change locally by >10%, which is a large change. © SPIE.


Wald A.,Global Science and Technology | Brinkmann J.,Science Systems And Applications Inc. | Wu A.,Science Systems And Applications Inc. | Xiong J.,NASA
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Terra MODIS has been known since pre-launch to have polarization sensitivity, particularly in shortest-wavelength bands 8 and 9. On-orbit reflectance trending of pseudo-invariant sites show a variation in reflectance as a function of band and scan mirror angle of incidence consistent with time-dependent polarization effects from the rotating doublesided scan mirror. The MODIS Characterization Support Team [MCST] estimates the Mueller matrix trending from this variation as observed from a single desert site, but this effect is not included in Collection 6 [C6] calibration. Here we extend the MCST's current polarization sensitivity monitoring to two ocean sites distributed over latitude to help estimate the uncertainties in the derived Mueller matrix. The Mueller matrix elements derived for polarization-sensitive Band 8 for a given site are found to be fairly insensitive to surface brdf modeling. The site-to-site variation is a measure of the uncertainty in the Mueller estimation. Results for band 8 show that the polarization correction reduces mirror-side striping by up to 50% and reduces the instrument polarization effect on reflectance time series of an ocean target. © SPIE.


Wu P.-H.,National Cheng Kung University | Lin I.-K.,Global Science and Technology | Lin I.-K.,NASA | Yan H.-Y.,National Cheng Kung University | And 3 more authors.
Sensors and Actuators, A: Physical | Year: 2011

In this paper, the mechanical and fracture properties of silicon nitride films subjected to rapid thermal annealing (RTA) have been systemically tested. The residual stress, Young's modulus, hardness, fracture toughness, and interfacial strength of both sputtered and plasma-enhanced chemical vapor deposition (PECVD) silicon nitride films deposited on silicon wafers were measured and compared. The results indicated that the Young's modulus and hardness of both types of silicon nitride films significantly increased when the RTA temperature increased. Furthermore, RTA processes could also alter the state of residual stress. The initial residual compressive stress of sputtered silicon nitride film was gradually relieved, and the film became tensile after the RTA process. For PECVD silicon nitride, the tensile residual stress reached its peak after a 600 °C RTA, then dropped after further increases in RTA temperature, due to stress relaxation. The tendency of the equivalent fracture toughness was to exhibit a strong correlation with that shown in the residual stress of silicon nitride. By considering the effect of residual stress, the real fracture toughness of both types of silicon nitride films were slightly enhanced by using RTA processes. Finally, experimental results indicated that the interfacial strength of PECVD silicon nitride could also be significantly improved by RTA processes at 600-800 °C. On the other hand, the initial interfacial strength of the sputtered silicon nitride was sufficiently strong, and the RTA processes only resulted in minor improvements. The characterization flow could be applied to other brittle films, and these specific test results should be useful for improving the structural integrity and process optimization of related MEMS and IC applications. © 2011 Elsevier B.V. All rights reserved.


Percivall G.,Open Geospatial Consortium | Alameh N.,Open Geospatial Consortium | Moe K.,NASA | Evans J.,Global Science and Technology
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2012

This paper describes how GEOSS and CEOS are individually and collaboratively strengthening the world's ability to manage the disasters lifecycle. The Architecture Implementation Pilot (AIP) of GEOSS has, through an agile development process, deployed and tested advanced information systems for Earth Observations based on interoperability arrangements. In particular AIP has focused on several Disaster Management Scenarios resulting in an architecture that has improved the ready viability and usability of data for disasters. CEOS is constructing a reference architecture, intended to streamline access to satellite data and services for disaster management. The CEOS approach aims to support disaster management activities with satellite information in a holistic fashion, taking account of their overlaps and interdependencies. Jointly GEOSS and CEOS are now working to align the approaches for Disaster Management to describe enterprise components and improve understanding of contributed systems and their roles. The coordination will lead to refinements of the Disaster Management Scenario via further implementation in AIP-5. By collaborating via the CEOS working groups and GEOSS communities of practice, these efforts are intended to engage the international community focused on disaster management to fully utilize remote sensing resources for societal benefit. © 2012 IEEE.


Jhabvala M.,NASA | Reuter D.,NASA | Choi K.,U.S. Army | Sundaram M.,QmagiQ, LLC | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

The Thermal Infrared Sensor (TIRS) is a QWIP based instrument intended to supplement the Operational Land Imager (OLI) for the Landsat Data Continuity Mission (LDCM) [1]. The TIRS instrument is a dual channel far infrared imager with the two bands centered at 10.8μm and 12.0μm. The focal plane assembly (FPA) consists of three 640x512 GaAs Quantum Well Infrared Photodetector (QWIP) arrays precisely mounted to a silicon carrier substrate that is mounted on an invar baseplate. The two spectral bands are defined by bandpass filters mounted in close proximity to the detector surfaces. The focal plane operating temperature is 43K. The QWIP arrays are hybridized to Indigo ISC9803 readout integrated circuits (ROICs). Two varieties of QWIP detector arrays are being developed for this project, a corrugated surface structure QWIP and a grating surface structure QWIP. This paper will describe the TIRS system noise equivalent temperature difference sensitivity as it affects the QWIP focal plane performance requirements: spectral response, dark current, conversion efficiency, read noise, temperature stability, pixel uniformity, optical crosstalk and pixel yield. Additional mechanical constraints as well as qualification through Technology Readiness Level 6 (TRL 6) will also be discussed. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Lin I.-K.,Global Science and Technology | Lin I.-K.,NASA | Zhang X.,Boston University | Zhang Y.,Boston University
Sensors and Actuators, A: Physical | Year: 2011

The application and commercialization of microelectromechanical system (MEMS) devices suffer from reliability problems due to the structural inelastic deformation during device operation. Nanocoatings have been demonstrated to be promising solutions for suppressing creep and stress relaxation in bilayer MEMS devices. However, the micro/nano-mechanics within and/or between microcantilevers and coatings are not fully understood, especially when temperature, time, and geometric and material nonlinearities play significant roles in the thermomechanical responses. In this study, the thermomechanical behavior of alumina-coated/uncoated Au/SiNx bilayer microcantilevers was characterized by using thermal cycling and isothermal holding tests. Finite element analysis with power-law creep was used to simulate the mechanical behavior of microcantilevers during isothermal holding. To better understand the stress evolution and the mechanism of inelastic deformation, scanning electron microscopy and atomic force microscopy was employed to explore the grain growth and grain boundary grooving after isothermal holding at various temperatures of 100 °C, 150 °C and 200 °C. The methods and results presented in this paper are useful for the fundamental understanding of many similar bilayer microcantilever-based MEMS devices. © 2011 Elsevier B.V. All rights reserved.

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