GLOBE Hydrology Workshop SEIP program

NASA Image and Video Library

2005-06-30

Matt Krigbaum (left), a teacher at Mitchell Elementary in Ann Arbor, Mich., pours water from the Pearl River into a turbidity tube to measure the river's light penetration. Krigbaum, along with Lois Williams, principal at Elizabeth Courville Elementary in Detroit, Mich.; and Carolyn Martin and Arlene Wittmer, teachers at Elizabeth Courville Elementary; conducted the experiment during a GLOBE (Global Learning and Observations to Benefit the Environment) hydrology workshop. GLOBE is a worldwide, hands-on science education program in which teachers can become certified to implement the program at their schools after taking hydrology, land cover/biology, atmosphere/climate and soil protocol workshops. Twelve teachers from across the country attended the recent weeklong GLOBE training at SSC, offered through its Educator Resource Center and the NASA Explorer Schools program. All workshops are free and offer continuing education units.

User's guide to the Nimbus-4 backscatter ultraviolet experiment data sets

NASA Technical Reports Server (NTRS)

Lowrey, B. E.

1978-01-01

The first year's data from the Nimbus 4 backscatter ultraviolet (BUV) experiment have been archived in the National Space Science Data Center (NSSDC). Backscattered radiances in the ultraviolet measured by the satellite were used to compute the global total ozone for the period April 1970 - April 1971. The data sets now in the NSSDC are the results obtained by the Ozone Processing Team, which has processed the data with the purpose of determining the best quality of the data. There are four basic sets of data available in the NSSDC representing various stages in processing. The primary data base contains organized and cleaned data in telemetry units. The radiance data has had most of the engineering calibrations performed. The detailed total ozone data is the result of computations to obtain the total ozone; the Compressed Total Ozone data is a convenient condensation of the detailed total ozone. Product data sets are also included.

Backscatter measurements for NIF ignition targets (invited).

PubMed

Moody, J D; Datte, P; Krauter, K; Bond, E; Michel, P A; Glenzer, S H; Divol, L; Niemann, C; Suter, L; Meezan, N; MacGowan, B J; Hibbard, R; London, R; Kilkenny, J; Wallace, R; Kline, J L; Knittel, K; Frieders, G; Golick, B; Ross, G; Widmann, K; Jackson, J; Vernon, S; Clancy, T

2010-10-01

Backscattered light via laser-plasma instabilities has been measured in early NIF hohlraum experiments on two beam quads using a suite of detectors. A full aperture backscatter system and near backscatter imager (NBI) instrument separately measure the stimulated Brillouin and stimulated Raman scattered light. Both instruments work in conjunction to determine the total backscattered power to an accuracy of ∼15%. In order to achieve the power accuracy we have added time-resolution to the NBI for the first time. This capability provides a temporally resolved spatial image of the backscatter which can be viewed as a movie.

GLOBE at Night: Scientific Research outside of the Classroom

NASA Astrophysics Data System (ADS)

Henderson, S.; Walker, C. E.; Geary, E.; Pompea, S. M.

2005-12-01

Increased and robust understanding of our environment requires learning opportunities that take place outside of the traditional K-12 classroom and beyond the confines of the school day. GLOBE at Night is a new event within The GLOBE Program that provides a mechanism for a nontraditional learning activity involving teachers, students, and their families taking observations of the night sky around the world and reporting their observations via a central data base for analysis. To support activities centered on authentic research experiences such as GLOBE at Night, The GLOBE Program has changed its approach to professional development (PD). The new focus of GLOBE PD efforts is centered on teachers being able to facilitate student research in and out of the classroom reflective of authentic scientific research experiences. It has been recognized that there is a critical need for effective teacher professional development programs that support teacher involvement in meaningful scientific research that encourages partnerships between scientists, teachers, and students. Partnerships promoting scientific research for K-12 audiences provides the foundation for The GLOBE Program, an international inquiry-based program designed to engage teachers with their students in partnership with research scientists to better understand the environment at local, regional, and global scales. GLOBE is an ongoing international science and education program that unites students, teachers, and scientists in the study of the Earth System. Students participating in GLOBE engage in hands-on activities, including the collection, analysis, and sharing of research quality scientific data with their peers around the world. Students interact with members of the science community who use the data collected from locations around the world in their research - data that would often not be available otherwise. As of September 2005, over 30,000 teachers representing over 16,000 schools worldwide have

Spatial and temporal variation of acoustic backscatter in the STRESS experiment

NASA Astrophysics Data System (ADS)

Dworski, J. George; Jackson, Darrell R.

1994-08-01

Acoustic backscatter measurements were made of the seabed with a bottom mounted, circularly scanning sonar. The placement was at 91 m depth, mid-shelf of Northern California (38° 34'N), site C3 of the experiment STRESS I (1988-1989). Our expectation was that sonar images (70 m radius, 12,000 m 2) would provide a means of observing, over a large field of view, changes in the bottom due to storm-induced sediment transport and due to bioturbation. This expectation was supported in part by towed sonar measurements at 35 kHz over a sandy area in the North Sea, where dramatic spatial variation in the level of the backseattered signal was observed during an Autumn storm on scales of a few km with no concomitant change in sediment grain size [ JACKSONet al. (1986) The Journal of the Acoustical Society of America, 80, 1188-1199]. It appeared possible that storm-driven sediment transport might have been responsible for this patchiness, by altering bottom roughness and by redeposition of suspended material. At the California site, a conventional sonar processing of our data from the STRESS experiment reveals no such dramatic change in backscattered signal level due to storms. The sonar images contain random structures whose time evolution is subtle and difficult to interpret. A much clearer picture of temporal and spatial variations emerges from a processing scheme involving cross-correlation of time-separated acoustic views of the bottom. In effect, the sequence of correlation data images produces a movie in which patches of activity are seen to develop as functions of time. It appears that most of this activity is biological rather than hydrodynamic. A tentative explanation is two-fold. The bottom shear stress might have been considerably greater at the North Sea site (with depth only one-half of the California site). The seafloor at the California site was silty-clayey, and backscatter from such floor is less sensitive to the water-floor interface shape and roughness than

12348_GLOBE_Observer_App_Promo

NASA Image and Video Library

2016-08-25

GLOBE Observer invites you to make environmental observations that complement NASA satellite observations to help scientists studying Earth and the global environment. Version 1.1 includes GLOBE Clouds, which allows you to photograph clouds and record sky observations and compare them with NASA satellite images. GLOBE is now the major source of human observations of clouds, which provide more information than automated systems. Future versions of GLOBE Observer will add additional tools for you to use as a citizen environmental scientist. By using the GLOBE Observer app, you are joining the GLOBE community and contributing important scientific data to NASA and GLOBE, your local community, and students and scientists worldwide. New and interested users are encouraged to go to observer.globe.gov to learn more about the GLOBE program, or learn more about the GLOBE Clouds protocol.

Lidar backscattering measurements of background stratospheric aerosols

NASA Technical Reports Server (NTRS)

Remsberg, E. E.; Northam, G. B.; Butler, C. F.

1979-01-01

A comparative lidar-dustsonde experiment was conducted in San Angelo, Texas, in May 1974 in order to estimate the uncertainties in stratospheric-aerosol backscatter for the NASA Langley 48-inch lidar system. The lidar calibration and data-analysis procedures are discussed. Results from the Texas experiment indicate random and systematic uncertainties of 35 and 63 percent, respectively, in backscatter from a background stratospheric-aerosol layer at 20 km.

Seafloor multibeam backscatter calibration experiment: comparing 45°-tilted 38-kHz split-beam echosounder and 30-kHz multibeam data

NASA Astrophysics Data System (ADS)

Ladroit, Yoann; Lamarche, Geoffroy; Pallentin, Arne

2018-06-01

Obtaining absolute seafloor backscatter measurements from hydrographic multibeam echosounders is yet to be achieved. We propose a low-cost experiment to calibrate the various acquisition modes of a 30-kHz Kongsberg EM 302 multibeam echosounder in a range of water depths. We use a 38-kHz Simrad EK60 calibrated fisheries split-beam echosounder mounted at 45° angle on the vessel's hull as a reference for the calibration. The processing to extract seafloor backscatter from the EK60 requires bottom detection, ray tracing and motion compensation to obtain acceptable geo-referenced backscatter measurements from this non-hydrographic system. Our experiment was run in Cook Strait, New Zealand, on well-known seafloor patches in shallow, mid, and deep-water depths. Despite acquisition issues due to weather, our results demonstrate the strong potential of such an approach to obtain system's absolute calibration which is required for quantitative use of backscatter strength data.

The aCORN backscatter-suppressed beta spectrometer

DOE PAGES

Hassan, M. T.; Bateman, F.; Collett, B.; ...

2017-06-16

Backscatter of electrons from a beta detector, with incomplete energy deposition, can lead to undesirable effects in many types of experiments. We present and discuss the design and operation of a backscatter-suppressed beta spectrometer that was developed as part of a program to measure the electron–antineutrino correlation coefficient in neutron beta decay (aCORN). An array of backscatter veto detectors surrounds a plastic scintillator beta energy detector. The spectrometer contains an axial magnetic field gradient, so electrons are efficiently admitted but have a low probability for escaping back through the entrance after backscattering. Lastly, the design, construction, calibration, and performance ofmore » the spectrometer are discussed.« less

Observations of Radar Backscatter at Ku and C Bands in the Presence of Large Waves during the Surface Wave Dynamics Experiment

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Li, Fuk K.; Lou, Shu-Hsiang; Neumann, Gregory; McIntosh, Robert E.; Carson, Steven C.; Carswell, James R.; Walsh, Edward J.; Donelan, Mark A.; Drennan, William M.

1995-01-01

Ocean radar backscatter in the presence of large waves is investigated using data acquired with the Jet Propulsion Laboratory NUSCAT radar at Ku band for horizontal and vertical polarizations and the University of Massachusetts CSCAT radar at C band for vertical polarization during the Surface Wave Dynamics Experiment. Off-nadir backscatter data of ocean surfaces were obtained in the presence of large waves with significant wave height up to 5.6 m. In moderate-wind cases, effects of large waves are not detectable within the measurement uncertainty and no noticeable correlation between backscatter coefficients and wave height is found. Under high-wave light-wind conditions, backscatter is enhanced significantly at large incidence angles with a weaker effect at small incidence angles. Backscatter coefficients in the wind speed range under consideration are compared with SASS-2 (Ku band), CMOD3-H1 (C band), and Plant's model results which confirm the experimental observations. Variations of the friction velocity, which can give rise to the observed backscatter behaviors in the presence of large waves, are presented.

GLOBE Program Teacher's Guide.

ERIC Educational Resources Information Center

1997

The GLOBE Program is a worldwide, hands-on educational program for elementary and secondary school students. GLOBE aims to increase student achievement in mathematics and science, awareness towards the environment, and improve science process skills through network technology. This teacher's guide provides an overview of the GLOBE program and…

HF coherent backscatter in the ionosphere: In situ measurements of SuperDARN backscatter with e-POP RRI

NASA Astrophysics Data System (ADS)

Perry, G. W.; James, H. G.; Hussey, G. C.; Howarth, A. D.; Yau, A. W.

2017-12-01

We report in situ polarimetry measurements of HF scattering obtained by the Enhanced Polar Outflow Probe (e-POP) Radio Receiver Instrument (RRI) during a coherent backscatter scattering event detected by the Saskatoon Super Dual Auroral Radar Network (SuperDARN). On April 1, 2015, e-POP conducted a 4 minute coordinated experiment with SuperDARN Saskatoon, starting at 3:38:44 UT (21:38:44 LT). Throughout the experiment, SuperDARN was transmitting at 17.5 MHz and e-POP's ground track moved in a northeastward direction, along SuperDARN's field-of-view, increasing in altitude from 331 to 352 km. RRI was tuned to 17.505 MHz, and recorded nearly 12,000 SuperDARN radar pulses during the experiment. In the first half of the experiment, radar pulses recorded by RRI were "well behaved": they retained their transmitted amplitude envelope, and their pulse-to-pulse polarization characteristics were coherent - Faraday rotation was easily measured. During the second half of the experiment the pulses showed clear signs of scattering: their amplitude envelopes became degraded and dispersed, and their pulse-to-pulse polarization characteristics became incoherent - Faraday rotation was difficult to quantify. While these pulses were being received by RRI, SuperDARN Saskatoon detected a latitudinal band of coherent backscatter at e-POP's location, indicating that the scattered pulses measured by RRI may be a signature of HF backscatter. In this presentation, we will outline the polarimetric details of the scattered pulses, and provide an analytic interpretation of RRI's measurements to give new insight into the nature of HF coherent backscatter mechanism taking place in the terrestrial ionosphere.

Displaying Annotations for Digitised Globes

NASA Astrophysics Data System (ADS)

Gede, Mátyás; Farbinger, Anna

2018-05-01

Thanks to the efforts of the various globe digitising projects, nowadays there are plenty of old globes that can be examined as 3D models on the computer screen. These globes usually contain a lot of interesting details that an average observer would not entirely discover for the first time. The authors developed a website that can display annotations for such digitised globes. These annotations help observers of the globe to discover all the important, interesting details. Annotations consist of a plain text title, a HTML formatted descriptive text and a corresponding polygon and are stored in KML format. The website is powered by the Cesium virtual globe engine.

Wet-Bulb-Globe Temperature Data Report

DTIC Science & Technology

2015-03-01

Hour Min Pressure Dry Nat Wet Globe Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPSc RH S1 WBGT Q WBGT...Wet Globe Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPSc RH S1 WBGT Q WBGT K2 WBGT GMT millibars deg F...Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPSc RH S1 WBGT Q WBGT K2 WBGT GMT millibars deg F deg F deg

GLOBE Program's Data and Information System

NASA Astrophysics Data System (ADS)

Memarsadeghi, N.; Overoye, D.; Lewis, C.; Butler, D. M.; Ramapriyan, H.

2016-12-01

"The Global Learning and Observations to Benefit the Environment (GLOBE) Program is an international science and education program that provides students and the public worldwide with the opportunity to participate in data collection and the scientific process, and contribute meaningfully to our understanding of the Earth system and global environment" (www.globe.gov ). GLOBE Program has a rich community of students, teachers, scientists, trainers, country coordinators, and alumni across the world, technologically spanning both high- and low-end users. There are 117 GLOBE participating countries from around the world. GLOBE's Science data protocols and educational material span atmosphere, biosphere, hydrosphere, soil (pedosphere), and Earth as a System scientific areas (http://www.globe.gov/do-globe/globe-teachers-guide). GLOBE's Data and Information System (DIS), when first introduced in 1995, was a cutting edge system that was well-received and innovative for its time. However, internet-based technologies have changed dramatically since then. Projects to modernize and evolve the GLOBE DIS started in 2010, resulting in today's GLOBE DIS. The current GLOBE DIS is now built upon the latest information technologies and is engaging and supporting the user community with advanced tools and services to further the goals of the GLOBE Program. GLOBE DIS consists of over 20 years of observation and training data, a rich set of software systems and applications for data entry, visualization, and analysis, as well as tools for training users in various science data protocols and enabling collaborations among members of the international user community. We present the existing GLOBE DIS, application technologies, and lessons learned for their operations, development, sustaining engineering, and data management practices. Examples of GLOBE DIS technologies include Liferay System for integrated user and content management, a Postgress/PostGIS database, Ruby on Rails for Data

Acoustical and optical backscatter measurements of sediment transport in the 1988 1989 STRESS experiment

NASA Astrophysics Data System (ADS)

Lynch, J. F.; Gross, T. F.; Sherwood, C. R.; Irish, J. D.; Brumley, B. H.

1997-04-01

During the 1988-1989 Sediment Transport Events on Shelves and Slopes (STRESS) experiment, a 1-MHz acoustic backscatter system (ABSS), deployed in 90 m of water off the California coast measured vertical profiles of suspended sediment concentration from 1.5 to (nominally) 26 meters above bottom (m.a.b.). An 8-week-long time series was obtained, showing major sediment transport events (storms) in late December and early January. Comparison of the acoustics measurements from 1.5 m.a.b. are made with optical backscatter system (OBS) concentration estimates lower in the boundary layer (0.25 m.a.b.). Correlations between ABSS and OBS concentration measurements and the boundary layer forcing functions (waves, currents, and their non-linear interaction) provided a variety of insights into the nature of the sediment transport of the STRESS site. Transport rates and integrated transport are seen to be dominated by the largest storm events.

Building the Capacity of HBCU's for Establishing Effective Globe Partnerships

NASA Technical Reports Server (NTRS)

Bagayoko, Diola; Ford, Robert L.

2002-01-01

The special GLOBE train-the-trainer (TTT) workshop entitled "Building the Capacity of HBCUs For Establishing Effective GLOBE Partnerships" was help for the purpose of expanding GLOBE training capacity on the campuses of Historically Black Colleges and Universities (HBCUs) and community colleges (CCs). The workshop was held March 17-22, 2002 in Washington, D.C. at Howard University. It was designed to establish research and instructional collaboration between and among U.S. universities (HBCUs and CCs) and African countries. Representatives from 13 HBCUs, and two community colleges were represented among trainees, so were representatives from eight African countries who were financially supported by other sources. A total of 38 trainees increased their knowledge of GLOBE protocols through five days of rigorous classroom instruction, field experiences, cultural events, and computer lab sessions.

Fiber optic backscatter spectroscopic sensor to monitor enamel demineralization and remineralization in vitro

PubMed Central

Kishen, Anil; Shrestha, Annie; Rafique, Adeela

2008-01-01

In this study, a Fiber Optic Backscatter Spectroscopic Sensor (FOBSS) is used to monitor demineralization and remineralization induced changes in the enamel. A bifurcated fiber optic backscatter probe connected to a visible light source and a high resolution spectrophotometer was used to acquire the backscatter light spectrum from the tooth surface. The experiments were conducted in two parts. In Part 1, experiments were carried out using fiber optic backscatter spectroscopy on (1) sound enamel and dentine sections and (2) sound tooth specimens subjected to demineralization and remineralization. In Part 2, polarization microscopy was conducted to examine the depth of demineralization in tooth specimens. The enamel and dentine specimens from the Part-1 experiments showed distinct backscatter spectra. The spectrum obtained from the enamel-dentine combination and the spectrum generated from the average of the enamel and dentine spectral values were closely similar and showed characteristics of dentine. The experiments in Part 2 showed that demineralization and remineralization processes induced a linear decrease and linear increase in the backscatter light intensity respectively. A negative correlation between the decrease in the backscatter light intensity during demineralization and the depth of demineralization determined using the polarization microscopy was calculated to be p = -0.994. This in vitro experiment highlights the potential benefit of using FOBSS to detect demineralization and remineralization of enamel. PMID:20142887

The GLOBE Earth Day 2004 Contrail Count-a-Thon

NASA Technical Reports Server (NTRS)

Chambers, Lin H.; Cole, Julia

2004-01-01

Early in 2004 the GLOBE Science team suggested a contrail count activity to celebrate Earth Day 2004, which was held this year on April 22nd in the United States and some other countries around the world. The GLOBE contrail team embraced this idea and developed a simplified data collection sheet for this special project. Information about the event was shared through the GLOBE site, UCAR and NASA press releases, the NASA portal (http://www.nasa.gov) and the CERES S'COOL Project (http://scool.larc.nasa.gov). On Earth Day, about 120 observations were received through the GLOBE Contrail Count-a-Thon website, about 70 contrail observations were received through regular GLOBE data reporting, and 19 contrail observations were received through regular S'COOL data reporting. Only observations between 11:00 and 13:00 local time were included in the Count-a-Thon. The event was reported in the Boulder Daily Camera beforehand and in the Oregon Register-Guard after the fact. It was also reported on National Public Radio s Day-to-Day show; whose host even submitted an observation. This poster discusses the Count-a-Thon experience and reports the results.

Relating P-band AIRSAR backscatter to forest stand parameters

NASA Technical Reports Server (NTRS)

Wang, Yong; Melack, John M.; Davis, Frank W.; Kasischke, Eric S.; Christensen, Norman L., Jr.

1993-01-01

As part of research on forest ecosystems, the Jet Propulsion Laboratory (JPL) and collaborating research teams have conducted multi-season airborne synthetic aperture radar (AIRSAR) experiments in three forest ecosystems including temperate pine forest (Duke, Forest, North Carolina), boreal forest (Bonanza Creek Experimental Forest, Alaska), and northern mixed hardwood-conifer forest (Michigan Biological Station, Michigan). The major research goals were to improve understanding of the relationships between radar backscatter and phenological variables (e.g. stand density, tree size, etc.), to improve radar backscatter models of tree canopy properties, and to develop a radar-based scheme for monitoring forest phenological changes. In September 1989, AIRSAR backscatter data were acquired over the Duke Forest. As the aboveground biomass of the loblolly pine forest stands at Duke Forest increased, the SAR backscatter at C-, L-, and P-bands increased and saturated at different biomass levels for the C-band, L-band, and P-band data. We only use the P-band backscatter data and ground measurements here to study the relationships between the backscatter and stand density, the backscatter and mean trunk dbh (diameter at breast height) of trees in the stands, and the backscatter and stand basal area.

The GLOBE Program: Partnerships in Action

NASA Astrophysics Data System (ADS)

Henderson, S.; Kennedy, T.; Lemone, M.; Blurton, C.

2004-12-01

The GLOBE Program is a worldwide science and education partnership endeavor designed to increase scientific understanding of Earth as a system, support improved student achievement in science and math, and enhance environmental awareness through inquiry-based learning activities. GLOBE began on the premise that teachers and their students would partner with scientists to collect and analyze environmental data using specific protocols in five study areas - atmosphere, soils, hydrology, land cover, and phenology. As the GLOBE network grew, additional partnerships flourished making GLOBE an unprecedented collaboration of individuals worldwide - primary, secondary, and tertiary students, teachers and teacher educators, scientists, government officials, and others - to improve K-12 education. Since its inception in 1994, more than one million students in over 14,000 schools around the world have taken part in The GLOBE Program. The GLOBE Web site (http://www.globe.gov) is the repository for over 11 million student-collected data measurements easily accessible to students and scientists worldwide. Utilizing the advantages of the Internet for information sharing and communication, GLOBE has created an international community. GLOBE enriches students by giving them the knowledge and skills that they will need to become informed citizens and responsible decision-makers in an increasingly complex world. Understanding that all members of a community must support change if it is to be sustainable, GLOBE actively encourages the development of GLOBE Learning Communities (GLCs) which are designed to get diverse stakeholder groups involved in a local or regional environmental issue. Central to the GLC is the engagement of local schools. GLCs go beyond individual teachers implementing GLOBE in the isolation of their classrooms. Instead, the GLC brings multiple teachers and grade levels together to examine environmental issues encouraging the participation of a broad range of

Elementary GLOBE: Inquiring About the Earth System Through Elementary Student Investigations

NASA Astrophysics Data System (ADS)

Henderson, S.; Hatheway, B.; Gardiner, L.; Gallagher, S.

2006-12-01

Elementary GLOBE was designed to introduce K-4 students to the study of Earth System Science (ESS). Elementary GLOBE forms an instructional unit comprised of five modules that address ESS and interrelated subjects including weather, hydrology, seasons, and soils. Each Elementary GLOBE module contains a science based storybook, classroom learning activities that complement the science content covered in each book, and teacher's notes. The storybooks explore a component of the Earth system and the associated classroom learning activities provide students with a meaningful introduction to technology, a basic understanding of the methods of inquiry, and connection to math and literacy skills. The science content in the books and activities serves as a springboard to GLOBE's scientific protocols. All Elementary GLOBE materials are freely downloadable (www.globe.gov/elementaryglobe) The use of science storybooks with elementary students has proven to be an effective practice in exposing students to science content while providing opportunities for students to improve their reading, writing, and oral communication skills. The Elementary GLOBE storybooks portray kids asking questions about the natural world, doing science investigations, and exploring the world around them. Through the storybook characters, scientific inquiry is modeled for young learners. The associated learning activities provide opportunities for students to practice science inquiry and investigation skills, including observation, recording, measuring, etc. Students also gain exposure and increase their comfort with different tools that scientists use. The learning activities give students experiences with asking questions, conducting scientific investigations, and scientific journaling. Elementary GLOBE fills an important niche in K-4 instruction. The international GLOBE Program brings together students, teachers, and scientists with the basic goals of increasing scientific understanding of the Earth

Reducing parametric backscattering by polarization rotation

DOE PAGES

Barth, Ido; Fisch, Nathaniel J.

2016-10-01

When a laser passes through underdense plasmas, Raman and Brillouin Backscattering can reflect a substantial portion of the incident laser energy. This is a major loss mechanism, for example, in employing lasers in inertial confinement fusion. But, by slow rotation of the incident linear polarization, the overall reflectivity can be reduced significantly. Particle in cell simulations show that, for parameters similar to those of indirect drive fusion experiments, polarization rotation reduces the reflectivity by a factor of 5. A general, fluid-model based analytical estimation for the reflectivity reduction agrees with simulations. However, in identifying the source of the backscatter reduction,more » it is difficult to disentangle the rotating polarization from the frequency separation based approach used to engineer the beam's polarization. Though the backscatter reduction arises similarly to other approaches that employ frequency separation, in the case here, the intensity remains constant in time.« less

Electron backscattering simulation in Geant4

NASA Astrophysics Data System (ADS)

Dondero, Paolo; Mantero, Alfonso; Ivanchencko, Vladimir; Lotti, Simone; Mineo, Teresa; Fioretti, Valentina

2018-06-01

The backscattering of electrons is a key phenomenon in several physics applications which range from medical therapy to space including AREMBES, the new ESA simulation framework for radiation background effects. The importance of properly reproducing this complex interaction has grown considerably in the last years and the Geant4 Monte Carlo simulation toolkit, recently upgraded to the version 10.3, is able to comply with the AREMBES requirements in a wide energy range. In this study a validation of the electron Geant4 backscattering models is performed with respect to several experimental data. In addition a selection of the most recent validation results on the electron scattering processes is also presented. Results of our analysis show a good agreement between simulations and data from several experiments, confirming the Geant4 electron backscattering models to be robust and reliable up to a few tens of electronvolts.

GLOBE Aerosol Field Campaign - U.S. Pilot Study 2016

NASA Technical Reports Server (NTRS)

Pippin, Margaret; Marentette, Christina; Bujosa, Robert; Taylor, Jessica; Lewis, Preston

2016-01-01

During the spring of 2016, from April 4 - May 27, sixteen GLOBE schools participated in the GLOBE Aerosol Field Campaign - U.S. Pilot Study. Thirteen teachers from these schools had previously participated in the NASA LEARN program (Long-term Experience in Authentic Research with NASA) where they were GLOBE trained in Atmosphere protocols, and engaged in 1-3 years of research under the mentorship of NASA scientists. Each school was loaned two aerosol instruments for the Campaign duration, either 2 GLOBE sun photometers, 2 Calitoo sun photometers, or 1 of each. This allowed for students to make measurements side-by-side and in the case of the Calitoos, to compare AOT results immediately with each other for better consistency in data collection. Additionally, as part of the Field Campaign evaluation, multiple instruments allow for an assessment of the ease of use of each instrument for grade level of students, whether in middle school or high school. Before the Campaign, all GLOBE and Calitoo instruments were 'checked out' against an AERONET, then checked again upon return after the Campaign. By examining all data, before, during and after the Campaign, this gives an indication of instrument performance and proficiency obtained by the students. Support was provided to each teacher and their students at the level requested, via email, phone or video conferencing.

World Wind: NASA's Virtual Globe

NASA Astrophysics Data System (ADS)

Hogan, P.

2007-12-01

Virtual globes have set the standard for information exchange. Once you've experienced the visually rich and highly compelling nature of data delivered via virtual globes with their highly engaging context of 3D, it's hard to go back to a flat 2D world. Just as the sawbones of not-too-long-ago have given way to sophisticated surgical operating theater, today's medium for information exchange is just beginning to leap from the staid chalkboards and remote libraries to fingertip navigable 3D worlds. How we harness this technology to serve a world inundated with information will describe the quality of our future. Our instincts for discovery and entertainment urge us on. There's so much we could know if the world's knowledge was presented to us in its natural context. Virtual globes are almost magical in their ability to reveal natural wonders. Anyone flying along a chain of volcanoes, a mid-ocean ridge or deep ocean trench, while simultaneously seeing the different depths to the history of earthquakes in those areas, will be delighted to sense Earth's dynamic nature in a way that would otherwise take several paragraphs of "boring" text. The sophisticated concepts related to global climate change would be far more comprehensible when experienced via a virtual globe. There is a large universe of public and private geospatial data sets that virtual globes can bring to light. The benefit derived from access to this data within virtual globes represents a significant return on investment for government, industry, the general public, and especially in the realm of education. Data access remains a key issue. Just as the highway infrastructure allows unimpeded access from point A to point B, an open standards-based infrastructure for data access allows virtual globes to exchange data in the most efficient manner possible. This data can be either free or proprietary. The Open Geospatial Consortium is providing the leadership necessary for this open standards-based data access

Effect of species structure and dielectric constant on C-band forest backscatter

NASA Technical Reports Server (NTRS)

Lang, R. H.; Landry, R.; Kilic, O.; Chauhan, N.; Khadr, N.; Leckie, D.

1993-01-01

A joint experiment between Canadian and USA research teams was conducted early in Oct. 1992 to determine the effect of species structure and dielectric variations on forest backscatter. Two stands, one red pine and one jack pine, in the Petawawa National Forestry Institute (PNFI) were utilized for the experiment. Extensive tree architecture measurements had been taken by the Canada Centre for Remote Sensing (CCRS) several months earlier by employing a Total Station surveying instrument which provides detailed information on branch structure. A second part of the experiment consisted of cutting down several trees and using dielectric probes to measure branch and needle permittivity values at both sites. The dielectric and the tree geometry data were used in the George Washington University (GWU) Vegetation Model to determine the C band backscattering coefficients of the individual stands for VV polarization. The model results show that backscatter at C band comes mainly from the needles and small branches and the upper portion of the trunks acts only as an attenuator. A discussion of variation of backscatter with specie structure and how dielectric variations in needles for both species may affect the total backscatter returns is provided.

Globes: A Librarian's Guide to Selection and Purchase.

ERIC Educational Resources Information Center

Coombs, James

1981-01-01

Provides a guide for librarians to use in selecting globes by discussing how globes are made, types of globes, special and extraterrestrial globes, selecting criteria, and comparing such features as aesthetic appeal, readability, and currency of political information. A list of globe manufacturers and a selected bibliography are provided. (CHC)

Anatomic features of the cetacean globe.

PubMed

Miller, Sarah; Samuelson, Don; Dubielzig, Richard

2013-07-01

To provide measurements of globe dimensions and describe morphological characteristics of the cetacean globe with an emphasis on Bowman's layer and encapsulated sensory corpuscles (ESC) for available cetacean species. Cetacean globes housed at the Comparative Ocular Pathology Laboratory of Wisconsin from various odontocete and two mysticete species. Measurements were taken from formalin fixed globes and images of formalin fixed globes with embedded rulers. Histological sections of globes were used to count ESC and measure Bowman's layer. The horizontal diameter of the globe was longer than the vertical diameter. The posterior sclera was thick, causing the internal axial length (and therefore the optical axis) to be shorter than the vertical diameter. The cornea was composed of an epithelium, Bowman's layer, collagenous stroma, thin Descemet's membrane and endothelial layer. Bowman's layer was present in all specimens except one Kogia breviceps. The thickness was variable, with the acellular layer thickest in Tursiops truncatus and thinnest in Kogia sp. The iris was well vascularized and muscled while the ciliary body lacked musculature, but retained vasculature. Single and clustered ESC were found in the anterior uvea, sclera surrounding the anterior uvea, trabecular meshwork, or some combination of these locations. They were often regionally grouped and varied from 0 to 21. There were three species where no ESC were found, L. borealis, D. capensis, and S. bredanensis, but the presence of these corpuscles cannot be ruled as only one section of the globe was analyzed. © 2013 American College of Veterinary Ophthalmologists.

Detailed Globes Enhance Education and Recreation

NASA Technical Reports Server (NTRS)

2007-01-01

Orbis World Globes creates inflatable globes-Earthballs-in many sizes that depict Earth as it is seen from space, complete with atmospheric cloud cover. Orbis designs and produces the most visually authentic replicas of Earth ever created, and NASA took notice of Orbis globes and employed a 16-inch diameter EarthBall for an educational film it made aboard the STS-45 shuttle mission. Orbis later collaborated with NASA to create two 16-foot diameter world globes for display at the 2002 Olympic Winter Games in Salt Lake City, using more detailed satellite imagery. The satellite image now printed on all Orbis globes displays 1-kilometer resolution and is 21,600 by 43,200 pixels in size, and Orbis globes are otherwise meteorologically accurate, though the cloud cover has been slightly reduced in order for most of the landforms to be visible. Orbis also developed the exclusive NightGlow Cities feature, enabling EarthBalls to display the world's cities as they appear as the Earth revolves from daylight into night. Orbis inflatable globes are available in sizes from 1 to 100 feet in diameter, with the most common being the standard 16-inch and 1-meter diameter EarthBalls. Applications include educational uses from preschools to universities, games, and for a variety of display purposes at conferences, trade shows, festivals, concerts, and parades. A 16-foot diameter Orbis globe was exhibited at the United Nations' World Urban Forum, in Vancouver, Canada; the Space 2006 conference, in San Jose, California; and the X-Prize Cup Personal Spaceflight Exposition in Las Cruces, New Mexico.

Average Annual Rainfall over the Globe

ERIC Educational Resources Information Center

Agrawal, D. C.

2013-01-01

The atmospheric recycling of water is a very important phenomenon on the globe because it not only refreshes the water but it also redistributes it over land and oceans/rivers/lakes throughout the globe. This is made possible by the solar energy intercepted by the Earth. The half of the globe facing the Sun, on the average, intercepts 1.74 ×…

GLOBE Goes GO with Mosquitoes

NASA Astrophysics Data System (ADS)

Boger, R. A.; Low, R.

2016-12-01

The GLOBE Mosquito Larvae protocol and a new citizen science initiative, GLOBE Observers (GO), were both launched in Summer 2016. While the GLOBE Mosquito Larvae Protocol and associated educational materials target K-16 student inquiry and research, the GO protocol version is simplified to enable citizen scientists of all ages from all walks of life to participate. GO allows citizen scientists to collect and submit environmental data through an easy-to-use smart phone app available for both Apple and Android mobile devices. GO mosquito asks for photos of larvae mosquito genus or species, location, and type of water source (e.g., container or pond) where the larvae were found. To initiate the new mosquito GLOBE/GO opportunities, workshops have been held in Barbuda, Thailand, West Indies, US Gulf Coast, New York City, and at the GLOBE Annual Meeting in Colorado. Through these venues, the protocols have been refined and a field campaign has been initiated so that GO and GLOBE citizen scientists (K-16 students and all others) can contribute data. Quality assurance measures are taken through the online training required to participate and the validation of identification by other citizen sciences and mosquito experts. Furthermore, initial research is underway to develop optical recognition software starting with the species that carry the Zika virus (Aedes aegypti and A. albopictus). With this launch, we plan to move forward by providing opportunities throughout the world to engage people in meaningful environmental and public health data collection and to promote citizen scientists to become agents of change in their communities.

Infrared backscattering

NASA Technical Reports Server (NTRS)

Bohren, Craig F.; Nevitt, Timothy J.; Singham, Shermila Brito

1989-01-01

All particles in the atmosphere are not spherical. Moreover, the scattering properties of randomly oriented nonspherical particles are not equivalent to those of spherical particles no matter how the term equivalent is defined. This is especially true for scattering in the backward direction and at the infrared wavelengths at which some atmospheric particles have strong absorption bands. Thus calculations based on Mie theory of infrared backscattering by dry or insoluble atmospheric particles are suspect. To support this assertion, it was noted that peaks in laboratory-measured infrared backscattering spectra show appreciable shifts compared with those calculated using Mie theory. One example is ammonium sulfate. Some success was had in modeling backscattering spectra of ammonium sulfate particles using a simple statistical theory called the continuous distribution of ellipsoids (CDE) theory. In this theory, the scattering properties of an ensemble are calculated. Recently a modified version of this theory was applied to measured spectra of scattering by kaolin particles. The particles were platelike, so the probability distribution of ellipsoidal shapes was chosen to reflect this. As with ammonium sulfate, the wavelength of measured peak backscattering is shifted longward of that predicted by Mie theory.

Thomson-backscattered x rays from laser-accelerated electrons.

PubMed

Schwoerer, H; Liesfeld, B; Schlenvoigt, H-P; Amthor, K-U; Sauerbrey, R

2006-01-13

We present the first observation of Thomson-backscattered light from laser-accelerated electrons. In a compact, all-optical setup, the "photon collider," a high-intensity laser pulse is focused into a pulsed He gas jet and accelerates electrons to relativistic energies. A counterpropagating laser probe pulse is scattered from these high-energy electrons, and the backscattered x-ray photons are spectrally analyzed. This experiment demonstrates a novel source of directed ultrashort x-ray pulses and additionally allows for time-resolved spectroscopy of the laser acceleration of electrons.

Map and Globe Reading Skills.

ERIC Educational Resources Information Center

Georgia State Dept. of Education, Atlanta. Office of Instructional Services.

Although the guide was designed to accompany an instructional television series, it contains teacher-developed activities on map and globe skills which can be selected and adapted to the needs of elementary students independent of the series. Geographic concepts include direction, the globe, boundaries, hemispheres, scale, latitude, longitude, and…

Dynamic coherent backscattering mirror

NASA Astrophysics Data System (ADS)

Zeylikovich, I.; Xu, M.

2016-02-01

The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation.

Ocean backscatter across the Gulf Stream sea surface temperature front

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nghiem, S.V.; Li, F.K.

1997-06-01

Ocean backscatter was measured by the Jet Propulsion Laboratory, with the airborne NUSCAT K{sub u}-band scatterometer, across the Gulf Stream sea surface temperature front during the Surface Wave Dynamics Experiment off the coast of Virginia and Maryland in the winter of 1991. Backscatter across the front between the National Oceanic and Atmospheric Administration experimental coastal buoy A (44024) on the cold side and Discus C buoy (44023) on the warm side shows a difference of more than 5 dB for vertical polarization in many cases. This large frontal backscatter change is observed in all upwind, downwind, and crosswind directions. Themore » sea surface temperature difference measured by the buoys was about 9{degrees}C. The corresponding difference in wind speed cannot account for the large backscatter change in view of geophysical model functions depending only on neutral wind velocity such as SASS. The measured backscatter also has larger upwind-downwind and upwind-crosswind ratios compared to the model results. Furthermore, NUSCAT data reveal that upwind backscatter on the cold side was smaller than or close to crosswind backscatter on the warm side for incidence angles between 30{degrees} to 50{degrees}. This suggests that the temperature front can be detected by the scatterometer at these incidence angles for different wind directions in the cold and warm sides.« less

Design of the optical backscatter diagnostic for laser plasma interaction measurements on NIF

NASA Astrophysics Data System (ADS)

Moody, J. D.; Datte, P.; Ng, E.; Maitland, K.; Hsing, W.; MacGowan, B. J.; Froula, D. H.; Neumayer, P.; Sutter, L.; Meezan, N.; Glenzer, S. H.; Kirkwood, R. K.; Divol, L.; Andrews, S.; Jackson, J.; MacKinnon, A.; Jovanovic, I.; Beeler, R.; Bertolini, L.; Landon, M.; Alvarez, S.; Lee, T.; Watts, P.

2007-11-01

We describe the design of the backscatter diagnostic for NIF laser-plasma interaction (LPI) studies. It will initially be used to validate the 280 eV point design hohlraum and select phase plates for the ignition experiments. Backscatter measurements are planned for two separate groups of 4 beams (a quad). One quad is 30^o from the hohlraum axis and the other at 50^o. The backscatter measurement utilizes 2 instruments for each beam quad. The full aperture backscatter system (FABS) measures light backscattered into the final focus lens of each beam in the quad. The near backscatter imager (NBI) measures light backscattered outside of the beam quad. Both instruments must work in conjunction to provide spectrally and temporally resolved backscatter power. We describe the design of the diagnostic and its capabilities as well as plans for calibrating it and analyzing the resulting data. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

Teacher Preparation with GLOBE and NASA Assets

NASA Astrophysics Data System (ADS)

Czajkowski, K. P.; Templin, M.; Struble, J.; Mierzwiak, S.; Hedley, M. L.; Padgett, D.

2017-12-01

The GLOBE Program has been a working with teachers and students for over 20 years. Pre-service education students can be a target audience as well. Mission EARTH is a NASA funded project through the NASA Cooperative Agreement Notice (CAN) from the Science Mission Directorate. A goal of Mission EARTH is to improve student understanding of Earth System Science and to engage the next generation of scientists and global citizens. This presentation will discuss Weather and Climate courses offered at both the University of Toledo and Tennessee State University for pre-service education students. Students engaged in atmospheric observations through the GLOBE protocols and developed research projects to study El Nino. Undergraduate students helped K-12 students take GLOBE observations as well by partnering with in-service GLOBE teachers affiliated with these GLOBE partnerships.

GLOBE Earth Science Education and Public Outreach in Developing Countries GLOBE Earth Science Education and Public Outreach in Developing Countries

NASA Astrophysics Data System (ADS)

Sparrow, E. B.; Boger, R. A.

2005-12-01

GLOBE is an international hands-on earth science education program that involves scientists, teachers and students in more than 16,000 primary and secondary schools. GLOBE is funded by the National Aeronautics Administration (NASA), the National Science Foundation (NSF) and the U.S. Department of State. GLOBE works with schools (teachers and students) through more than 100 U.S. GLOBE partnerships with universities, state and local school systems, and non-government organizations. Internationally, GLOBE is partnered with 109 countries that include many developing nations throughout the world. In addition to the GLOBE's different areas of investigation e.g. Atmosphere/ Weather, Hydrology, Soils, Land Cover Biology and Phenology ( plant and animal), there are special projects such as the GLOBE Urban Phenology Year Project (GUPY) that engages developing and developed countries ( Finland, United States, Japan, Philippines, Thailand, Jordan, Kyrgystan, Senegal, Poland, Estonia, and the Dominican Republic) in studying the effects of urbanization on vegetation phenology, a sensitive indicator of climate change. Vegetation phenology integrates different components of the Earth system i.e. carbon and geochemical cycling, water cycling and energy cycling and is an excellent way to engage students in collaborative projects. This presentation will highlight the GUPY project and provide additional examples of local initiatives and collaborations with indigenous communities that use GLOBE and an inquiry approach to revise science education in developing countries .

Average Annual Rainfall Over the Globe

NASA Astrophysics Data System (ADS)

Agrawal, D. C.

2013-12-01

The atmospheric recycling of water is a very important phenomenon on the globe because it not only refreshes the water but it also redistributes it over land and oceans/rivers/lakes throughout the globe. This is made possible by the solar energy intercepted by the Earth. The half of the globe facing the Sun, on the average, intercepts 1.74×1017 J of solar radiation per second and it is divided over various channels as given in Table 1. It keeps our planet warm and maintains its average temperature2 of 288 K with the help of the atmosphere in such a way that life can survive. It also recycles the water in the oceans/rivers/ lakes by initial evaporation and subsequent precipitation; the average annual rainfall over the globe is around one meter. According to M. King Hubbert the amount of solar power going into the evaporation and precipitation channel is 4.0×1016 W. Students can verify the value of average annual rainfall over the globe by utilizing this part of solar energy. This activity is described in the next section.

Assessing backscatter change due to backscatter gradient over the Greenland ice sheet using Envisat and SARAL altimetry

NASA Astrophysics Data System (ADS)

Su, Xiaoli; Luo, Zhicai; Zhou, Zebing

2018-06-01

Knowledge of backscatter change is important to accurately retrieve elevation change time series from satellite radar altimetry over continental ice sheets. Previously, backscatter coefficients generated in two cases, namely with and without accounting for backscatter gradient (BG), are used. However, the difference between backscatter time series obtained separately in these two cases and its impact on retrieving elevation change are not well known. Here we first compare the mean profiles of the Ku and Ka band backscatter over the Greenland ice sheet (GrIS), with results illustrating that the Ku-band backscatter is 3 ∼ 5 dB larger than that of the Ka band. We then conduct statistic analysis about time series of backscatter formed separately in the above two cases for both Ku and Ka bands over two regions in the GrIS. It is found that the standard deviation of backscatter time series becomes slightly smaller after removing the BG effect, which suggests that the method for the BG correction is effective. Furthermore, the impact on elevation change from backscatter change due to the BG effect is separately assessed for both Ku and Ka bands over the GrIS. We conclude that Ka band altimetry would benefit from a BG induced backscatter analysis (∼10% over region 2). This study may provide a reference to form backscatter time series towards refining elevation change time series from satellite radar altimetry over ice sheets using repeat-track analysis.

The globe and orbit in Laron syndrome.

PubMed

Kornreich, L; Konen, O; Lilos, P; Laron, Z

2011-09-01

Patients with LS have an inborn growth hormone resistance, resulting in failure to generate IGF-1. The purpose of this study was to evaluate the size of the eye and orbit in LS. We retrospectively reviewed the MR imaging of the brain in 9 patients with LS for the following parameters: axial diameter of the globe, interzygomatic distance, perpendicular distance from the interzygomatic line to margins of the globe, medial-to-lateral diameter of the orbit at the anterior orbital rim, distance from the anterior orbital rim to the anterior globe, maximal distance between the medial walls of the orbits, lateral orbital wall angle, lateral orbital wall length, and mediolateral thickness of the intraorbital fat in the most cranial image of the orbit. All measurements were made bilaterally. Twenty patients referred for MR imaging for unrelated reasons served as control subjects. Compared with the control group, the patients with LS had a significantly smaller maximal globe diameter and shallower but wider orbits due to a shorter lateral wall, a smaller medial distance between the orbits, and a larger angle of the orbit. The ratio between the most anterior orbital diameter and the globe was greater than that in controls. The position of the globe was more anterior in relation to the interzygomatic line. Shallow and wide orbits and small globes relative to orbital size are seen in LS and may be secondary to IGF-1 deficiency.

The Process of Digitizing of Old Globe

NASA Astrophysics Data System (ADS)

Ambrožová, K.; Havrlanta, J.; Talich, M.; Böhm, O.

2016-06-01

This paper describes the process of digitalization of old globes that brings with it the possibility to use globes in their digital form. Created digital models are available to the general public through modern technology in the Internet network. This gives an opportunity to study old globes located in various historical collections, and prevent damage of the originals. Another benefit of digitization is also a possibility of comparing different models both among themselves and with current map data by increasing the transparency of individual layers. Digitization is carried out using special device that allows digitizing globes with a diameter ranging from 5 cm to 120 cm. This device can be easily disassembled, and it is fully mobile therefore the globes can be digitized in the place of its storage. Image data of globe surface are acquired by digital camera firmly fastened to the device. Acquired image data are then georeferenced by using a method of complex adjustment. The last step of digitization is publication of the final models that is realized by two ways. The first option is in the form of 3D model through JavaScript library Cesium or Google Earth plug-in in the Web browser. The second option is as a georeferenced map using Tile Map Service.

Theoretical and experimental models of the diffuse radar backscatter from Mars

NASA Technical Reports Server (NTRS)

England, A. W.

1995-01-01

The general objective for this work was to develop a theoretically and experimentally consistent explanation for the diffuse component of radar backscatter from Mars. The strength, variability, and wavelength independence of Mars' diffuse backscatter are unique among our Moon and the terrestrial planets. This diffuse backscatter is generally attributed to wavelength-scale surface roughness and to rock clasts within the Martian regolith. Through the combination of theory and experiment, the authors attempted to bound the range of surface characteristics that could produce the observed diffuse backscatter. Through these bounds they gained a limited capability for data inversion. Within this umbrella, specific objectives were: (1) To better define the statistical roughness parameters of Mars' surface so that they are consistent with observed radar backscatter data, and with the physical and chemical characteristics of Mars' surface as inferred from Mariner 9, the Viking probes, and Earth-based spectroscopy; (2) To better understand the partitioning between surface and volume scattering in the Mars regolith; (3) To develop computational models of Mars' radio emission that incorporate frequency dependent, surface and volume scattering.

Cavitation inception by the backscattering of pressure waves from a bubble interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahira, Hiroyuki, E-mail: takahira@me.osakafu-u.ac.jp; Ogasawara, Toshiyuki, E-mail: oga@me.osakafu-u.ac.jp; Mori, Naoto, E-mail: su101064@edu.osakafu-u.ac.jp

2015-10-28

The secondary cavitation that occurs by the backscattering of focused ultrasound from a primary cavitation bubble caused by the negative pressure part of the ultrasound (Maxwell, et al., 2011) might be useful for the energy exchange due to bubble oscillations in High Intensity Focused Ultrasound (HIFU). The present study is concerned with the cavitation inception by the backscattering of ultrasound from a bubble. In the present experiment, a laser-induced bubble which is generated by a pulsed focused laser beam with high intensity is utilized as a primary cavitation bubble. After generating the bubble, focused ultrasound is emitted to the bubble.more » The acoustic field and the bubble motion are observed with a high-speed video camera. It is confirmed that the secondary cavitation bubble clouds are generated by the backscattering from the laser-induced bubble. The growth of cavitation bubble clouds is analyzed with the image processing method. The experimental results show that the height and width of the bubble clouds grow in stepwise during their evolution. The direct numerical simulations are also conducted for the backscattering of incident pressure waves from a bubble in order to evaluate a pressure field near the bubble. It is shown that the ratio of a bubble collapse time t{sub 0} to a characteristic time of wave propagation t{sub S}, η = t{sub 0}/t{sub s}, is an important determinant for generating negative pressure region by backscattering. The minimum pressure location by the backscattering in simulations is in good agreement with the experiment.« less

Turning Content into Conversation: How The GLOBE Program is Growing its Brand Online

NASA Astrophysics Data System (ADS)

Zwerin, R.; Randolph, J. G.; Andersen, T.; Mackaro, J.; Malmberg, J.; Tessendorf, S. A.; Wegner, K.

2012-12-01

Social Media is now a ubiquitous way for individuals, corporations, governments and communities to communicate. However, the same does not hold quite as true for the science community as many science educators, thought leaders and science programs are either reluctant or unable to build and cultivate a meaningful social media strategy. This presentation will show how The GLOBE Program uses social media to disseminate messages, build a meaningful and engaged following and grow a brand on an international scale using a proprietary Inside-Out strategy that leverages social media platforms such as Facebook, LinkedIn, Twitter, YouTube and Blogs to significantly increase influencers on a worldwide scale. In addition, this poster presentation will be interactive, so viewers will be able to touch and feel the social experience. Moreover, GLOBE representatives will be on hand to talk viewers through how they can implement a social media strategy that will allow them to turn their content into meaningful conversation. About The GLOBE Program: GLOBE is a science and education program that connects a network of students, teachers and scientists from around the world to better understand, sustain and improve Earth's environment at local, regional and global scales. By engaging students in hands-on learning of Earth system science, GLOBE is an innovative way for teachers to get students of all ages excited about scientific discovery locally and globally. To date, more than 23 million measurements have been contributed to the GLOBE database, creating meaningful, standardized, global research-quality data sets that can be used in support of student and professional scientific research. Since beginning operations in 1995, over 58,000 trained teachers and 1.5 million students in 112 countries have participated in GLOBE. For more information or to become involved, visit www.globe.gov.

Electromagnetic backscattering from one-dimensional drifting fractal sea surface II: Electromagnetic backscattering model

NASA Astrophysics Data System (ADS)

Tao, Xie; William, Perrie; Shang-Zhuo, Zhao; He, Fang; Wen-Jin, Yu; Yi-Jun, He

2016-07-01

Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, the Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service Program.

GLOBE and Place-based learning

NASA Astrophysics Data System (ADS)

Andersen, T. J.; Murphy, T.; Malmberg, J. S.; Wegner, K.

2016-12-01

You visit a special natural setting and are amazed at the splendor. You revisit it years later at the same time of year and note how it has changed. The environment looks different-algae is growing where it didn't before. Trees are dying. Weeds are flourishing. You ask yourself "why is this happening?" The spark starting your climate place-based awareness just ignited. The GLOBE program encourages and enables young citizen scientists to observe and record measurements related to the environment and to use those measurements for research. Over 130 learning activities supplement the 51 measurement protocols that can be done in and out of the field, with and without technical devices that open up the mind to questions about one's environment. From taking pictures of the sky to creating instruments, to noting when plants bloom and examining the characteristics of the soil and land, GLOBE encourages investigating climate change in numerous ways. GLOBE activities encouraging climate awareness and "what if" scenarios fuel student research and help validate scientific research. Studying one's local GLOBE observations and seeing where and when change occurs, brings out intrigue that expands to investigating multiple places where even more questions can arise-fueling the scientific process and encouraging place-based learning.

Bilateral Traumatic Globe Luxation with Optic Nerve Transection

PubMed Central

Tok, Levent; Tok, Ozlem Yalcin; Argun, Tugba Cakmak; Yilmaz, Omer; Gunes, Alime; Unlu, Elif Nisa; Sezer, Sezgin; Ibisoglu, Seda; Argun, Mehmet

2014-01-01

Purpose The purpose of this study was to document clinical findings and management of a patient with bilateral globe luxation and optic nerve transection. Materials and Methods A 25-year-old female patient was admitted to the emergency department with bilateral traumatic globe luxation following a motor vehicle accident. Results Visual acuity testing showed no light perception. The right pupil was dilated and bilaterally did not react to light. The globes were bilaterally intact. A computed tomography scan revealed Le Fort type II fractures, bilateral optic nerve transection and disruption of all extraocular muscles. The globes of the patient were bilaterally reduced into the orbit. However, the patient developed phthisis bulbi in the right eye at month 3. Conclusion Globe luxation presents a dramatic clinical picture, and may lead to the development of severe complications due to the concomitance of complete optic nerve dissection and multiple traumas. Even if the luxated globe is repositioned into the orbit, there is still an increased risk of the development of phthisis due to ischemia. PMID:25606034

The GLOBE Program 10 Years On: Challenges and Opportunities

NASA Astrophysics Data System (ADS)

Blurton, C.

2004-12-01

The initiative for the GLOBE Program, a hands-on primary and secondary school-based Earth science and education program that unites students, teachers and scientists in study and research about the dynamics of the Earth's environment, was first announced on Earth Day, April 22, 1994, by then-Vice President Al Gore. The U.S. National Oceanic and Atmospheric Administration (NOAA) was designated as GLOBE's lead agency. Along with NOAA, the National Aeronautics and Space Administration (NASA), the National Science Foundation (NSF), and the Environmental Protection Agency (EPA) provided funding, and the Department of State, although not a funding agency, was involved in the development and implementation of the international aspects of the program. The US Agency for International Development (USAID) and the Peace Corps have also provided support to GLOBE in other countries. GLOBE started up with just a few hundred schools and teachers but quickly grew over the years largely through the efforts of the growing number of International Partners and U.S. Partners such as universities, school districts and others. In December 2003, over 25,000 teachers in more than 14,500 schools in 105 countries had been trained to implement GLOBE in their classrooms. Students in those classrooms had contributed over 11,000,000 individual environmental measurements to the GLOBE database. In September 2002, NASA assumed lead U.S. federal agency responsibility for GLOBE and shortly thereafter issued a Cooperative Agreement Notice to solicit proposals to assume responsibility in assisting NASA in the management of the GLOBE Program, including both worldwide implementation and coordination in the U.S. A Cooperative Agreement between NASA and the University Corporation for Atmospheric Research (UCAR) for the Program entitled: Inspiring the Next Generation of Explorers: The GLOBE Program (NCC5-735) was signed June 16, 2003. UCAR's partner in implementing GLOBE is Colorado State University (CSU

Investigation of microwave backscatter from the air-sea interface

NASA Technical Reports Server (NTRS)

Mcintosh, Robert E.; Carswell, James R.

1995-01-01

Monitoring the ocean surface winds and mean ocean surface level is essential for improving our knowledge of the climate. Two instruments that may provide us with this information are satellite-based scatterometers and altimeters. However, these instruments measure the backscatter characteristics of the ocean surface from which other physical parameters, such as the wind speed or ocean surface height, are derived. To improve the algorithms or models that relate the electromagnetic backscatter to the desired physical parameters, the University of Massachusetts (UMass) Microwave Remote Sensing Laboratory (MIRSL) designed and fabricated three airborne scatterometers: a C-band scatterometer (CSCAT), Ku-band scatterometer (KUSCAT) and C/Ku-band scatterometer (EMBR). One or more of these instruments participated in the Electromagnetic Bias experiment (EM Bias), Shelf Edge Exchange Processes experiment (SEEP), Surface Wave Dynamics Experiment (SWADE), Southern Ocean Wave Experiment (SOWEX), Hurricane Tina research flights, Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE), and Ladir In-space Technology Experiment (LITE). This document describes the three scatterometers, summarizes our measurement campaigns and major contributions to the scientific and engineering communities, lists the publications that resulted, and presents the degrees earned under the support of this NASA grant.

Occupational open globe injuries.

PubMed

Vasu, U; Vasnaik, A; Battu, R R; Kurian, M; George, S

2001-03-01

Occupational ocular trauma is an important cause of acquired monocular blindness in a rapidly industrialising country like India. Knowledge of the epidemiology of occupational eye injuries is essential to formulate viable industrial safety measures. We retrospectively reviewed all patients with occupational open globe injuries between 1994 and 1998. We documented the circumstances of the injuries, their clinical findings and the use of appropriate protective eyewear at the time of the injury. The visual acuity 6 months after the injury was the final outcome measure. In this study period we examined 43 patients with open globe injuries sustained at the work place. Thirty-four (79.1%) patients were young males. The iron and steel industry accounted for 19 (44.2%) cases while 8 (18.6%) patients each were from the agricultural, mining and other small scale industrial sectors. At the time of the injury, 33 (76.7%) were not wearing the recommended protective eyewear and 6 (13.9%) were under the influence of alcohol. The injuries were mild in 6 (13.9%), moderate in 18 (41.9%) and severe in 19 (44.2%) patients. At the end of 6 months, 2 (4.7%) patients had a visual acuity of 6/12 or better, 4 (9.3%) had a visual acuity of 6/18 to 6/60 and 29 (67.4.%) had a vision of <6/60. Eight (18.6%) patients were not available for follow up. Occupational open globe injuries are usually severe and are associated with a poor visual outcome. Mandatory use of protective eyewear and alcohol-free environment at the work place is likely to reduce the incidence of severe occupational open globe injuries.

Enhanced backscattering of optical waves due to densely distributed scatterers

NASA Astrophysics Data System (ADS)

Ma, Yushieh; Varadan, Vijay K.; Varadan, Vasundara V.

1988-01-01

Using multiple scattering theory, the T matrix of a pair of scatterers which takes all back-and-forth scattering between the pair members into account and considers multiple scattering effects in the intensity calculation is used to calculate the magnitude and the width of the backscattered intensity peak. Generally, at low concentrations, both the magnitude of the scattered intensity and multiple scattering contributions are not sufficiently strong to reach the enhanced-backscattering threshold. The results obtained are consistent with those yielded by optical experiments.

Multibeam Sonar Backscatter Data Acquisition and Processing: Guidelines and Recommendations from the GEOHAB Backscatter Working Group

NASA Astrophysics Data System (ADS)

Heffron, E.; Lurton, X.; Lamarche, G.; Brown, C.; Lucieer, V.; Rice, G.; Schimel, A.; Weber, T.

2015-12-01

Backscatter data acquired with multibeam sonars are now commonly used for the remote geological interpretation of the seabed. The systems hardware, software, and processing methods and tools have grown in numbers and improved over the years, yet many issues linger: there are no standard procedures for acquisition, poor or absent calibration, limited understanding and documentation of processing methods, etc. A workshop organized at the GeoHab (a community of geoscientists and biologists around the topic of marine habitat mapping) annual meeting in 2013 was dedicated to seafloor backscatter data from multibeam sonars and concluded that there was an overwhelming need for better coherence and agreement on the topics of acquisition, processing and interpretation of data. The GeoHab Backscatter Working Group (BSWG) was subsequently created with the purpose of documenting and synthetizing the state-of-the-art in sensors and techniques available today and proposing methods for best practice in the acquisition and processing of backscatter data. Two years later, the resulting document "Backscatter measurements by seafloor-mapping sonars: Guidelines and Recommendations" was completed1. The document provides: An introduction to backscatter measurements by seafloor-mapping sonars; A background on the physical principles of sonar backscatter; A discussion on users' needs from a wide spectrum of community end-users; A review on backscatter measurement; An analysis of best practices in data acquisition; A review of data processing principles with details on present software implementation; and finally A synthesis and key recommendations. This presentation reviews the BSWG mandate, structure, and development of this document. It details the various chapter contents, its recommendations to sonar manufacturers, operators, data processing software developers and end-users and its implication for the marine geology community. 1: Downloadable at https://www.niwa.co.nz/coasts-and-oceans/research-projects/backscatter-measurement-guidelines

The Inverted Snow Globe Shadow

NASA Astrophysics Data System (ADS)

Ribeiro, Jair Lúcio Prados

2015-01-01

Our high school optics course finishes with an assignment that students usually appreciate. They must take pictures of everyday situations representing optical phenomena such as reflection, refraction, or dispersion, and post them on Instagram.1 When the photos were presented to the class, one student revealed an intriguing photo, similar to Fig. 1, showing a snow globe exposed to sunlight and its inverted shadow. This paper offers an explanation of the problem, which occurs due to light refraction from the globe.

Ku-band ocean radar backscatter observations during SWADE

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Li, F. K.; Lou, S. H.; Neumann, G.

1993-01-01

We present results obtained by an airborne Ku-band scatterometer during the Surface Wave Dynamics Experiment (SWADE). The specific objective of this study is to improve our understanding of the relationship between ocean radar backscatter and near surface winds. The airborne scatterometer, NUSCAT, was flown on the NASA Ames C-130 over an instrumented oceanic area near 37 deg N and 74 deg W. A total of 10 flights from 27 Feb. to 9 Mar. 1991 were conducted. Radar backscatter at incidence angles of 0 to 60 deg were obtained. For each incidence angle, the NUSCAT antenna was azimuthally scanned in multiple complete circles to measure the azimuthal backscatter modulations. Both horizontal and vertical polarization backscatter measurements were made. In some of the flights, the cross-polarization backscatter was measured as well. Internal calibrations were carried out throughout each of the flights. Preliminary results indicate that the radar was stable to +/-0.3 dB for each flight. In this paper, we present studies of the backscatter measurements over several crossings of the Gulf Stream. In these crossings, large air-sea temperature differences were encountered and substantial changes in the radar cross section were observed. We summarize the observations and compare them to the changes of several wind variables across the Gulf Stream boundary. In one of the flights, the apparent wind near the cold side of the Gulf Stream was very low (less than 3 m/s). The behavior of the radar cross sections at such low wind speeds and a comparison with models are presented. A case study of the effects of swell on the absolute cross section and the azimuthal modulation pattern is presented. Significant wave heights larger than m were observed during SWADE. The experimentally observed effects of the swell on the radar backscatter are discussed. The effects are used to assess the uncertainties in wind retrieval due to underlying waves. A summary of azimuthal modulation from our ten

Airborne detection of oceanic turbidity cell structure using depth-resolved laser-induced water Raman backscatter

NASA Technical Reports Server (NTRS)

Hoge, F. E.; Swift, R. N.

1983-01-01

Airborne laser-induced, depth-resolved water Raman backscatter is useful in the detection and mapping of water optical transmission variations. This test, together with other field experiments, has identified the need for additional field experiments to resolve the degree of the contribution to the depth-resolved, Raman-backscattered signal waveform that is due to (1) sea surface height or elevation probability density; (2) off-nadir laser beam angle relative to the mean sea surface; and (3) the Gelbstoff fluorescence background, and the analytical techniques required to remove it. When converted to along-track profiles, the waveforms obtained reveal cells of a decreased Raman backscatter superimposed on an overall trend of monotonically decreasing water column optical transmission.

Raised Relief Mars Globe Brings the Red Planet Closer

NASA Technical Reports Server (NTRS)

2006-01-01

The Mars Globe 20x is the first digitally produced raised relief globe to be sold at retail establishments. The rises and dips of the Martian landscape have been multiplied by 20 to make the shapes more noticeable to human touch and sight. They make this globe, with its over 1 million elevation points, a visually stunning introduction to the planet. Spectrum 3D used the NASA digital land elevation data to aim lasers that then shaped and defined the master globe s surface. Subsequent copies were then made by creating a master globe mold. The molded copies are hand finished by workers who remove errant edges or lines that may appear on the raw globes and then paint the surfaces. The result is a globe that measures in at 18 inches in diameter, roughly 1:15,729,473 scale of the actual planet. The exaggerated raised relief is like having a 3-D digital microscope for planetary shapes. This makes the landmarks easier to learn and understand, as it provides easy visuals for orientation. People have a natural propensity for understanding 3-D shapes more easily than numbers or words. The 3-D globes appeal to both the kinetic and visual learning aspects of the brain, making it easy for people to readily memorize the landmarks and to make a mental model that they will remember for a long time.

Artificially controlled backscattering in single mode fibers based on femtosecond laser fabricated reflectors

NASA Astrophysics Data System (ADS)

Wang, Xiaoliang; Chen, Daru; Li, Haitao; Wu, Qiong

2018-04-01

A novel method to artificially control the backscattering of the single-mode fiber (SMF) is proposed and investigated for the first time. This method can help to fabricate a high backscattering fiber (HBSF), such as by fabricating reflectors in every one meter interval of an SMF based on the exposure of the femtosecond laser beam. The artificially controlled backscattering (ACBS) can be much higher than the natural Rayleigh backscattering (RB) of the SMF. The RB power and ACBS power in the unit length fiber are derived according to the theory of the RBS. The total relative power and the relative back power reflected in the unit length of the HBSF have been simulated and presented. The simulated results show that the HBSF has the characteristics of both low optical attenuation and high backscattering. The relative back power reflected in the unit length of the HBSF is 25dB larger than the RB power of the SMF when the refractive index modulation quantity of the reflectors is 0.009. Some preliminary experiments also indicate that the method fabricating reflectors to increase the backscattering power of the SMF is practical and promising.

Development of a global model for atmospheric backscatter at CO2 wavelengths

NASA Technical Reports Server (NTRS)

Kent, G. S.; Wang, P. H.; Farrukh, U.; Deepak, A.; Patterson, E. M.

1986-01-01

The variation of the aerosol backscattering at 10.6 micrometers within the free troposphere was investigated and a model to describe this variation was developed. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets used were obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series, and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained that describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season.

Using The GLOBE Program to address the Global Development Goals

NASA Astrophysics Data System (ADS)

Wegner, K.; Murphy, T.; Wigbels, L.; Mauriello, H.; Kucera, P. A.

2016-12-01

The GLOBE Program (globe.gov) is an international science and education program in more than 110 countries that provides students and the public worldwide the opportunity to participate in the scientific process through Earth observations and geospatial information. To address the Global Goals for Sustainable Development, The GLOBE Program has collaborated with with international organizations such as the UNEP, Peace Corps, USAID, UNESCO, Eco-Schools, and SciStarter to address the Goals for Sustainable Development. In this presentation, GLOBE will share the alignment materials that they have created to provide pathways to achieving the goals, as well as present case studies that demonstrate how the GLOBE community uses GLOBE protocols as Earth observations to monitor and communicate environmental indicators aligned to the Global Development Goals.

Globe at Night: From IYA2009 to the International Year of Light 2015 and Beyond

NASA Astrophysics Data System (ADS)

Walker, Constance Elaine; Pompea, Stephen M.; Sparks, Robert T.

2015-08-01

Citizen-science is a rewardingly inclusive way to bring awareness to the public on important issues like the disappearing starry night sky, its cause and solutions. Citizen-science can also provide meaningful, hands-on “science process” experiences for students. One program that does both is Globe at Night (www.globeatnight.org), an international campaign to raise public awareness of the impact of light pollution by having people measure night-sky brightness and submit observations via a “web app” on any smart device or computer. Additionally, 2 native mobile apps - Loss of the Night for iPhone & Android, and Dark Sky Meter for iPhone - support Globe at Night.Since 2006, more than 125,000 vetted measurements from 115 countries have been reported. For 2015 the campaign is offered as a 10-day observation window each month when the Moon is not up. To facilitate Globe at Night as an international project, the web app and other materials are in many languages. (See www.globeatnight.org/downloads.)Students and the general public can use the data to monitor levels of light pollution around the world, as well as understand light pollution’s effects on energy consumption, plants, wildlife, human health and our ability to enjoy a starry night sky. Projects have compared Globe at Night data with ground-truthing using meters for energy audits as well as with data on birds and bats, population density, satellite data and trends over time. Globe at Night tackles grand challenges and everyday problems. It provides resources for formal and informal educators to engage learners of all ages. It has 9 years of experience in best practices for data management, design, collection, visualization, interpretation, etc. It has externally evaluated its program, workshops, lesson plans and accompanying kit to explore reasons for participation, skills developed, impact of experiences and perceived outcomes. Three recent papers (Birriel et al. 2014; Kyba et al. 2013; 2015) verify the

Multibeam sonar backscatter data processing

NASA Astrophysics Data System (ADS)

Schimel, Alexandre C. G.; Beaudoin, Jonathan; Parnum, Iain M.; Le Bas, Tim; Schmidt, Val; Keith, Gordon; Ierodiaconou, Daniel

2018-06-01

Multibeam sonar systems now routinely record seafloor backscatter data, which are processed into backscatter mosaics and angular responses, both of which can assist in identifying seafloor types and morphology. Those data products are obtained from the multibeam sonar raw data files through a sequence of data processing stages that follows a basic plan, but the implementation of which varies greatly between sonar systems and software. In this article, we provide a comprehensive review of this backscatter data processing chain, with a focus on the variability in the possible implementation of each processing stage. Our objective for undertaking this task is twofold: (1) to provide an overview of backscatter data processing for the consideration of the general user and (2) to provide suggestions to multibeam sonar manufacturers, software providers and the operators of these systems and software for eventually reducing the lack of control, uncertainty and variability associated with current data processing implementations and the resulting backscatter data products. One such suggestion is the adoption of a nomenclature for increasingly refined levels of processing, akin to the nomenclature adopted for satellite remote-sensing data deliverables.

The GLOBE Contrail Protocol: Initial Analysis of Results

NASA Technical Reports Server (NTRS)

Chambers, Lin; Duda, David

2004-01-01

The GLOBE contrail protocol was launched in March 2003 to obtain surface observer reports of contrail occurrence to complement satellite and model studies underway at NASA Langley, among others. During the first year, more than 30,000 ground observations of contrails were submitted to GLOBE. An initial analysis comparing the GLOBE observations to weather prediction model results for relative humidity at flight altitudes is in progress. This paper reports on the findings to date from this effort.

Development of global model for atmospheric backscatter at CO2 wavelengths

NASA Technical Reports Server (NTRS)

Kent, G. S.; Wang, P. H.; Farrukh, U.; Deepak, A.; Patterson, E. M.

1985-01-01

The improvement of an understanding of the variation of the aerosol backscattering at 10.6 micron within the free troposphere and the development model to describe this was undertaken. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets are obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained, which describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season. Most data are available and greatest consistency is found inside the Northern Hemisphere.

Australian aerosol backscatter survey

NASA Technical Reports Server (NTRS)

Gras, John L.; Jones, William D.

1989-01-01

This paper describes measurements of the atmospheric backscatter coefficient in and around Australia during May and June 1986. One set of backscatter measurements was made with a CO2 lidar operating at 10.6 microns; the other set was obtained from calculations using measured aerosol parameters. Despite the two quite different data collection techniques, there is quite good agreement between the two methods. Backscatter values range from near 1 x 10 to the -8th/m per sr near the surface to 4 - 5 x 10 to the -11th/m per sr in the free troposphere at 5-7-km altitude. The values in the free troposphere are somewhat lower than those typically measured at the same height in the Northern Hemisphere.

GLOBE Observer: Earth Science in the Palm of Your Hand

NASA Astrophysics Data System (ADS)

Weaver, K. L. K.; Riebeek Kohl, H.

2017-12-01

You can get involved in doing Earth system science research tied to NASA research and data. This demo will introduce GLOBE and GLOBE Observer, a student and citizen science program designed to collect observations of the environment. The GLOBE Observer app, released in September 2016, harnesses smart phone technology to simplify select GLOBE observations to open the program to new audiences and to increase data volume. The end goal is to facilitate new student and scientific research. The demo will provide an overview of the app and show you how to access GLOBE Observer environmental data. The app includes a protocol for observing clouds and sky color (air quality proxy), mosquito habitats, and land cover/land use. The GLOBE Observer observations may be matched to NASA satellite data for a more in-depth analysis.

Backscatter from metal surfaces in diagnostic radiology.

PubMed

Kodera, Y; Schmidt, R A; Chan, H P; Doi, K

1984-01-01

Backscatter from four commonly used metals (aluminum, lead, copper, and iron) was measured under diagnostic imaging conditions, using screen-film systems as detectors. The results indicate that for an 80-kV filtered beam and Par Speed/XRP system, backscatter increases as aluminum (Al) thickness increases until it reaches a plateau of approximately 12% at 50 mm Al. The amount of backscatter from any of these four metals increases as the tube voltage is raised from 60 to 115 kV. Measured backscatter depends strongly on the screens used, possibly due to their attenuation and energy response. Backscatter from aluminum was significantly greater than that from the other metals tested.

Diurnal Thermal Cycling Effects on Backscatter of Thin Sea Ice

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Gow, A. J.; Perovich, D. K.; Hsu, C. C.; Ding, K. H.; Kong, J. A.; Grenfell, T. C.

1996-01-01

To invesigate effects on polarimetric backscatter of sea ice grown under diurnal cycling conditions, we carried out an experiment inJanuary 1994 at the outdoor Geophysical Research Facility in the Cold Regions Research and Engineering Laboratory.

Backscatter from metal surfaces in diagnostic radiology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kodera, Y.; Schmidt, R.A.; Chan, H.P.

Backscatter from four commonly used metals (aluminum, lead, copper, and iron) was measured under diagnostic imaging conditions, using screen-film systems as detectors. The results indicate that for an 80-kV filtered beam and Par Speed/XRP system, backscatter increases as aluminum (Al) thickness increases until it reaches a plateau of approximately 12% at 50 mm Al. The amount of backscatter from any of these four metals increases as the tube voltage is raised from 60 to 115 kV. Measured backscatter depends strongly on the screens used, possibly due to their attenuation and energy response. Backscatter from aluminum was significantly greater than thatmore » from the other metals tested.« less

The relationship between VHF radar auroral backscatter amplitude and Doppler velocity: a statistical study

NASA Astrophysics Data System (ADS)

Shand, B. A.; Lester, M.; Yeoman, T. K.

1996-08-01

A statistical investigation of the relationship between VHF radar auroral backscatter intensity and Doppler velocity has been undertaken with data collected from 8 years operation of the Wick site of the Sweden And Britain Radar-auroral Experiment (SABRE). The results indicate three different regimes within the statistical data set; firstly, for Doppler velocities <200 m s-1, the backscatter intensity (measured in decibels) remains relatively constant. Secondly, a linear relationship is observed between the backscatter intensity (in decibels) and Doppler velocity for velocities between 200 m s-1 and 700 m s-1. At velocities greater than 700 m s-1 the backscatter intensity saturates at a maximum value as the Doppler velocity increases. There are three possible geophysical mechanisms for the saturation in the backscatter intensity at high phase speeds: a saturation in the irregularity turbulence level, a maximisation of the scattering volume, and a modification of the local ambient electron density. There is also a difference in the dependence of the backscatter intensity on Doppler velocity for the flow towards and away from the radar. The results for flow towards the radar exhibit a consistent relationship between backscatter intensity and measured velocities throughout the solar cycle. For flow away from the radar, however, the relationship between backscatter intensity and Doppler velocity varies during the solar cycle. The geometry of the SABRE system ensures that flow towards the radar is predominantly associated with the eastward electrojet, and flow away is associated with the westward electrojet. The difference in the backscatter intensity variation as a function of Doppler velocity is attributed to asymmetries between the eastward and westward electrojets and the geophysical parameters controlling the backscatter amplitude.

Radar backscatter from the sea: Controlled experiments

NASA Astrophysics Data System (ADS)

Moore, R. K.

1992-04-01

The subwindowing method of modelling synthetic-aperture-radar (SAR) imaging of ocean waves was extended to allow wave propagation in arbitrary directions. Simulated images show that the SAR image response to swells that are imaged by velocity bunching is reduced by random smearing due to wind-generated waves. The magnitude of this response is not accurately predicted by introducing a finite coherence time in the radar backscatter. The smearing does not affect the imaging of waves by surface radar cross-section modulation, and is independent of the wind direction. Adjusting the focus of the SAR processor introduces an offset in the image response of the surface scatters. When adjusted by one-half the azimuthal phase velocity of the wave, this compensates the incoherent advance of the wave being imaged, leading to a higher image contrast. The azimuthal cut-off and range rotation of the spectral peak are predicted when the imaging of wind-generated wave trains is simulated. The simulated images suggest that velocity bunching and azimuthal smearing are strongly interdependent, and cannot be included in a model separately.

C-band backscattering from corn canopies

NASA Technical Reports Server (NTRS)

Daughtry, C. S. T.; Ranson, K. J.; Biehl, L. L.

1991-01-01

A frequency-modulatad continuous-wave C-band (4.8 GHz) scatterometer was mounted on an aerial lift truck, and backscatter coefficients of corn (Zea mays L.) were acquired as functions of polarizations, view angles, and row directions. As phytomass and green-leaf area index increased, the backscatter also increased. Near anthesis, when the canopies were fully developed, the major scattering elements were located in the upper 1 m of the 2.8 m tall canopy and little backscatter was measured below that level for view angles of 30 deg or greater. C-band backscatter data could provide information to monitor tillage operations at small view zenith angles and vegetation at large view zenith angles.

Driver's side curtain air bag-related globe rupture.

PubMed

Porter, Ashley J; Hayes, Rylan; Lee, Lawrence; O'Hagan, Stephen

2018-06-04

A 35-year-old man presented after a high-speed motor vehicle accident and the driver's side curtain air bag causing blunt force trauma rupturing his right globe. The tangential force of the air bag resulted in an unusual arcuate horseshoe-shaped rupture through the lateral rectus insertion, causing avulsion of the muscle and tearing the sclera, with the apices of the tear extending anteriorly towards the limbus. Repair of the globe rupture was undertaken, and secondary vitrectomy revealed that the scleral tear had not involved the retina abutting the ora serrata. Silicone oil tamponade was used to fill the globe and the postoperative best corrected vision was 6/9. This is the first reported case of a ruptured globe caused by a side curtain air bag, resulting in a uniquely shaped arcuate scleral wound combined with lateral rectus avulsion, not associated with rhegmatogenous retinal damage, and is the first air bag-related globe rupture with scleral involvement to report a final best-corrected visual acuity better than 6/60. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

A Backscatter-Lidar Forward-Operator

NASA Astrophysics Data System (ADS)

Geisinger, Armin; Behrendt, Andreas; Wulfmeyer, Volker; Vogel, Bernhard; Mattis, Ina; Flentje, Harald; Förstner, Jochen; Potthast, Roland

2015-04-01

We have developed a forward-operator which is capable of calculating virtual lidar profiles from atmospheric state simulations. The operator allows us to compare lidar measurements and model simulations based on the same measurement parameter: the lidar backscatter profile. This method simplifies qualitative comparisons and also makes quantitative comparisons possible, including statistical error quantification. Implemented into an aerosol-capable model system, the operator will act as a component to assimilate backscatter-lidar measurements. As many weather services maintain already networks of backscatter-lidars, such data are acquired already in an operational manner. To estimate and quantify errors due to missing or uncertain aerosol information, we started sensitivity studies about several scattering parameters such as the aerosol size and both the real and imaginary part of the complex index of refraction. Furthermore, quantitative and statistical comparisons between measurements and virtual measurements are shown in this study, i.e. applying the backscatter-lidar forward-operator on model output.

The isolation and mapping of a novel hydroxycinnamoyltransferase in the globe artichoke chlorogenic acid pathway

PubMed Central

Comino, Cinzia; Hehn, Alain; Moglia, Andrea; Menin, Barbara; Bourgaud, Frédéric; Lanteri, Sergio; Portis, Ezio

2009-01-01

Background The leaves of globe artichoke and cultivated cardoon (Cynara cardunculus L.) have significant pharmaceutical properties, which mainly result from their high content of polyphenolic compounds such as monocaffeoylquinic and dicaffeoylquinic acid (DCQ), and a range of flavonoid compounds. Results Hydroxycinnamoyl-CoA:quinate hydroxycinnamoyltransferase (HQT) encoding genes have been isolated from both globe artichoke and cultivated cardoon (GenBank accessions DQ915589 and DQ915590, respectively) using CODEHOP and PCR-RACE. A phylogenetic analysis revealed that their sequences belong to one of the major acyltransferase groups (anthranilate N-hydroxycinnamoyl/benzoyltransferase). The heterologous expression of globe artichoke HQT in E. coli showed that this enzyme can catalyze the esterification of quinic acid with caffeoyl-CoA or p-coumaroyl-CoA to generate, respectively, chlorogenic acid (CGA) and p-coumaroyl quinate. Real time PCR experiments demonstrated an increase in the expression level of HQT in UV-C treated leaves, and established a correlation between the synthesis of phenolic acids and protection against damage due to abiotic stress. The HQT gene, together with a gene encoding hydroxycinnamoyl-CoA:shikimate/quinate hydroxycinnamoyltransferase (HCT) previously isolated from globe artichoke, have been incorporated within the developing globe artichoke linkage maps. Conclusion A novel acyltransferase involved in the biosynthesis of CGA in globe artichoke has been isolated, characterized and mapped. This is a good basis for our effort to understand the genetic basis of phenylpropanoid (PP) biosynthesis in C. cardunculus. PMID:19292932

GLOBE-al Impact through Diversity Bootcamps and Student Research Symposia

NASA Astrophysics Data System (ADS)

Bourgeault, J.; Murphy, T.; Johnson, J.; Sparrow, E. B.; Czajkowski, K. P.; Herron, S.; Falcon, P.

2016-12-01

Inclusion, diversity, underrepresented groups, underserved populations...the key words and phrases that represent the students, we, as science education professionals, want to reach and encourage to enter the geoscience pipeline. Wanting to do this is one thing and having the skills to succeed is very different. It is also one that the GLOBE Program, an international science and education program, is working on as a community. GLOBE encourages students from around the world to participate in authentic scientific research of the Earth system. Students use scientific protocols to explore their local environments, compare their findings with other GLOBE schools both in the U.S. and in other participating countries, and then share their findings via the GLOBE.gov website. In the last year, two initiatives, six face-to-face Student Research Symposia and two diversity-focused GLOBE Partner Bootcamps, set the GLOBE community of Partners, teachers and students on the path to being able to address this challenge. This presentation will include the framework for the student research symposia, the barriers the leadership team faced when recruiting and getting students there and the lessons learned. Agendas for the GLOBE Partner Bootcamps will be shared to demonstrate how facilitators supplemented a standard GLOBE Partner workshop to model a more inclusive environment, along with future improvements to the format.

Globe Teachers Guide and Photographic Data on the Web

NASA Technical Reports Server (NTRS)

Kowal, Dan

2004-01-01

The task of managing the GLOBE Online Teacher s Guide during this time period focused on transforming the technology behind the delivery system of this document. The web application transformed from a flat file retrieval system to a dynamic database access approach. The new methodology utilizes Java Server Pages (JSP) on the front-end and an Oracle relational database on the backend. This new approach allows users of the web site, mainly teachers, to access content efficiently by grade level and/or by investigation or educational concept area. Moreover, teachers can gain easier access to data sheets and lab and field guides. The new online guide also included updated content for all GLOBE protocols. The GLOBE web management team was given documentation for maintaining the new application. Instructions for modifying the JSP templates and managing database content were included in this document. It was delivered to the team by the end of October, 2003. The National Geophysical Data Center (NGDC) continued to manage the school study site photos on the GLOBE website. 333 study site photo images were added to the GLOBE database and posted on the web during this same time period for 64 schools. Documentation for processing study site photos was also delivered to the new GLOBE web management team. Lastly, assistance was provided in transferring reference applications such as the Cloud and LandSat quizzes and Earth Systems Online Poster from NGDC servers to GLOBE servers along with documentation for maintaining these applications.

Backscatter from metal surfaces in diagnostic radiology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kodera, Y.; Schmidt, R.A.; Chan, H.P.

Backscatter from four commonly used metals (aluminum, lead, copper, and iron) was measured under diagnostic imaging conditions, using screen-film systems as detectors. The results indicate that for an 80-kV filtered beam and Par Speed/XRP system, backscatter increases as aluminum (Al) thickness increases until it reaches a plateau of approximately 12% at 50 mm Al. The amount of backscatter depends strongly on the screen used, possibly due to their attenuation and energy response. Backscatter from aluminum was significantly greater than that from the other metals tested.

Long-term variation of radar-auroral backscatter and the interplanetary sector structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeoman, T.K.; Burrage, M.D.; Lester, M.

Recurrent variation of geomagnetic activity at the {approximately}27-day solar rotation period and higher harmonics is a well-documented phenomenon. Auroral radar backscatter data from the Sweden and Britain Radar-Auroral Experiment (SABRE) radar provide a continuous time series from 1981 to the present which is a highly sensitive monitor of geomagnetic activity. In this study, Maximum Entropy Method (MEM) dynamic power spectra of SABRE backscatter data from 1981 to 1989, concurrent interplanetary magnetic field (IMF) and solar wind parameters from 1981 to 1987, and the Kp index since 1932 are examined. Data since 1977 are compared with previously published heliospheric current sheetmore » measurements mapped out from the solar photosphere. Stong periodic behavior is observed in the radar backscatter during the declining phase of solar cycle 21, but this periodicity disappears at the start of solar cycle 22. Similar behavior is observed in earlier solar cycles in the Kp spectra. Details of the radar backscatter, IMF, and solar wind spectra indicate that the solar wind momentum density is the dominant parameter in determining the backscatter periodicity. The temporal evolution of two- and four-sector structures, as predicted by SABRE backscatter spectra, throughout solar cycle 21 generally still agree well with heliospheric current sheet measurements. For one interval, however, there is evidence that evolution of the current sheet has occurred between the photospheric source surface and the Earth.« less

Processing ultrasound backscatter to monitor high-intensity focused ultrasound (HIFU) therapy

NASA Astrophysics Data System (ADS)

Kaczkowski, Peter J.; Anand, Ajay; Bailey, Michael R.

2005-09-01

The development of new noninvasive surgical methods such as HIFU for the treatment of cancer and internal bleeding requires simultaneous development of new sensing approaches to guide, monitor, and assess the therapy. Ultrasound imaging using echo amplitude has long been used to map tissue morphology for diagnostic interpretation by the clinician. New quantitative ultrasonic methods that rely on amplitude and phase processing for tissue characterization are being developed for monitoring of ablative therapy. We have been developing the use of full wave ultrasound backscattering for real-time temperature estimation, and to image changes in tissue backscatter spectrum as therapy progresses. Both approaches rely on differential processing of the backscatter signal in time, and precise measurement of phase differences. Noise and artifacts from motion and nonstationary speckle statistics are addressed by constraining inversions for tissue parameters with physical models. We present results of HIFU experiments with static point and scanned HIFU exposures in which temperature rise can be accurately mapped using a new heat transfer equation (HTE) model-constrained inverse approach. We also present results of a recently developed spectral imaging method that elucidates microbubble-mediated nonlinearity not visible as a change in backscatter amplitude. [Work supported by Army MRMC.

Backscattering from targets residing in caustics resulting from ocean boundary interactions

NASA Astrophysics Data System (ADS)

Dzikowicz, Benjamin R.; Marston, Philip L.

2005-04-01

Detection of targets by backscatter in shallow water can be enhanced by interactions with ocean boundaries. A laboratory experiment is performed where a spherical target passes through an Airy caustic formed by a curved surface. When the target resides in the insonified region of the caustic there are two sets of multi-path rays: two pairs reflecting once off the surface (either to or from the target), and three reflecting twice off the surface (to and from the target). When a target moves across the caustic the singly reflected rays merge, as do the doubly reflected. With a longer tone burst the rays in each set overlap and the backscatter is greatly enhanced as the target moves into the insonified region. For a point target the singly reflected backscatter scales as an Airy function [B. R. Dzikowicz and P. L. Marston, J. Acoust. Soc. Am. 116, 2751-2757 (2004)], and the doubly reflected as the square of an Airy function. For a finite target the doubly reflected backscatter unfolds into a hyperbolic umbilic function. The arguments of the Airy and Hyperbolic Umbilic functions are calculated using the relative echo times of transient pulses. [Work supported by ONR.

Crowd-Sourcing with K-12 citizen scientists: The Continuing Evolution of the GLOBE Program

NASA Astrophysics Data System (ADS)

Murphy, T.; Wegner, K.; Andersen, T. J.

2016-12-01

Twenty years ago, the Internet was still in its infancy, citizen science was a relatively unknown term, and the idea of a global citizen science database was unheard of. Then the Global Learning and Observations to Benefit the Environment (GLOBE) Program was proposed and this all changed. GLOBE was one of the first K-12 citizen science programs on a global scale. An initial large scale ramp-up of the program was followed by the establishment of a network of partners in countries and within the U.S. Now in the 21st century, the program has over 50 protocols in atmosphere, biosphere, hydrosphere and pedosphere, almost 140 million measurements in the database, a visualization system, collaborations with NASA satellite mission scientists (GPM, SMAP) and other scientists, as well as research projects by GLOBE students. As technology changed over the past two decades, it was integrated into the program's outreach efforts to existing and new members with the result that the program now has a strong social media presence. In 2016, a new app was launched which opened up GLOBE and data entry to citizen scientists of all ages. The app is aimed at fresh audiences, beyond the traditional GLOBE K-12 community. Groups targeted included: scouting organizations, museums, 4H, science learning centers, retirement communities, etc. to broaden participation in the program and increase the number of data available to students and scientists. Through the 20 years of GLOBE, lessons have been learned about changing the management of this type of large-scale program, the use of technology to enhance and improve the experience for members, and increasing community involvement in the program.

Evaluation and Strategic Planning for the GLOBE Program

NASA Astrophysics Data System (ADS)

Geary, E. E.; Williams, V. L.

2010-12-01

The Global Learning and Observations to Benefit the Environment (GLOBE) Program is an international environmental education program. It unites educators, students and scientists worldwide to collaborate on inquiry based investigations of the environment and Earth system science. Evaluation of the GLOBE program has been challenging because of its broad reach, diffuse models of implementation, and multiple stakeholders. In an effort to guide current evaluation efforts, a logic model was developed that provides a visual display of how the GLOBE program operates. Using standard elements of inputs, activities, outputs, customers and outcomes, this model describes how the program operates to achieve its goals. The template used to develop this particular logic model aligns the GLOBE program operations with its program strategy, thus ensuring that what the program is doing supports the achievement of long-term, intermediate and annual goals. It also provides a foundation for the development of key programmatic metrics that can be used to gauge progress toward the achievement of strategic goals.

The relationship of the globe to the orbital rim.

PubMed

Eckstein, Lauren A; Shadpour, Joseph M; Menghani, Ravi; Goldberg, Robert A

2011-01-01

To present a novel method for accurately characterizing the position of the globe relative to the orbital rim. The appearance and function of the eyelids are dependent on the underlying orbital bony architecture and globe position; however, no comprehensive language to describe these complex 3-dimensional relationships exists. Three-dimensional orbital reconstructions were generated from computed tomographic scans of 15 Occidental and 12 Oriental orbits without orbital pathologic disease. Globe and orbital rim anatomy were identified and outlined. Reference points were measured along 2 independent axes: (1) the distance between a plane defined by the corneal apex and the sagittal projection of the orbital rim and (2) the distance between the circumference of the globe and the coronal projection of the orbital rim. For Occidental orbits, the mean (SD) elevation of the sagittal projection of the orbital rim relative to the anterior projection of the globe was 4.6 (4.2) mm superiorly, 5.9 (3.0) mm nasally, 12.6 (3.7) mm inferiorly, and 20.6 (2.6) mm laterally. The mean (SD) radial distance between the coronal projection of the orbital rim and the circumference of the globe was 3.7 (2.1) mm superiorly, 7.6 (1.8) mm nasally, 6.6 (2.2) mm inferiorly, and 4.6 (2.3) mm laterally. For Oriental orbits, the mean (SD) elevation of the sagittal projection of the orbital rim relative to the anterior projection of the globe was 5.0 (4.5) mm superiorly, 6.8 (4.1) mm nasally, 11.1 (4.3) mm inferiorly, and 17.5 (3.3) mm laterally. The mean (SD) radial distance between the coronal projection of the orbital rim and the circumference of the globe was 2.1 (1.2) mm superiorly, 8.2 (2.0) mm nasally, 6.5 (1.9) mm inferiorly, and 4.5 (1.7) mm laterally. Comparison of Occidental and Oriental orbital rim and globe configurations revealed quantitative and qualitative differences. In addition to differences in soft-tissue anatomy, bony architectural variations may contribute substantially to

Place-based Learning About Climate with Elementary GLOBE

NASA Astrophysics Data System (ADS)

Hatheway, B.; Gardiner, L. S.; Harte, T.; Stanitski, D.; Taylor, J.

2017-12-01

Place-based education - helping students make connections between themselves, their community, and their local environment - is an important tool to help young learners understand their regional climate and start to learn about climate and environmental change. Elementary GLOBE storybooks and learning activities allow opportunities for place-based education instructional strategies about climate. In particular, two modules in the Elementary GLOBE unit - Seasons and Climate - provide opportunities for students to explore their local climate and environment. The storybooks and activities also make connections to other parts of elementary curriculum, such as arts, geography, and math. Over the long term, place-based education can also encourage students to be stewards of their local environment. A strong sense of place may help students to see themselves as stakeholders in their community and its resilience. In places that are particularly vulnerable to the impacts of climate and environmental change and the economic, social, and environmental tradeoffs of community decisions, helping young students developing a sense of place and to see the connection between Earth science, local community, and their lives can have a lasting impact on how a community evolves for decades to come. Elementary GLOBE was designed to help elementary teachers (i.e., grades K-4) integrate Earth system science topics into their curriculum as they teach literacy skills to students. This suite of instructional materials includes seven modules. Each module contains a science-based storybook and learning activities that support the science content addressed in the storybooks. Elementary GLOBE modules feature air quality, climate, clouds, Earth system, seasons, soil, and water. New eBooks allow students to read stories on computers or tablets, with the option of listening to each story with an audio recording. A new Elementary GLOBE Teacher Implementation Guide, published in 2017, provides

A study on the impact of the GLOBE program on students' attitudes regarding environmental issues

NASA Astrophysics Data System (ADS)

Manfready, Gary Martin

A key objective in environmental curricula should be to instill responsible and concerned attitudes toward environmental issues. This can be accomplished through the application of innovative programs which emphasize the development of the affective domain of learning. The development of personal attitudes is one form of evidence that the affective domain is being addressed. This study was undertaken to determine the impact of the GLOBE program (Global Learning and Observation to Benefit the Environment) on the attitudes of students toward environmental issues. Three hundred and five middle and high school level students from four states were surveyed to determine their attitudes toward selected environmental statements. Results demonstrated that attitudes toward environmental issues of GLOBE students were significantly greater than non-GLOBE students. Additional analysis demonstrated that regardless of grade levels, gender, racial and ethnicity backgrounds, depth of GLOBE involvement, and degree of teachers' GLOBE experiences, GLOBE students display similar levels of attitudes toward environmental issues. Establishment of a reliable Likert scale measurement instrument was accomplished. Permission to use an existing survey was obtained. Additional items were added to increase validity. Establishment of reliability was accomplished through a Guttman split half analysis of the piloted instrument. Through the use of factor analysis, four categories or sub-groupings of attitudes were determined to exist. Reliability was established for the factors. These sub-groupings were identified as personal commitment to environmental protection, awareness of avenues for action, loci of control, and students' perception of teachers' abilities to present environmental topics. These categories were a part of the analysis of four hypotheses.

Using the GLOBE Program To Enhance Classroom Teaching.

ERIC Educational Resources Information Center

Ramey, Linda K.; Tomlin, James

The Wright State University Global Learning and Observations to Benefit the Environment (GLOBE) Franchise has developed a project to fill the need for direct, strong connections linking science, mathematics and technology to classroom curriculum and students' learning of integrated, relevant content. GLOBE is an international project that involves…

A method for removing arm backscatter from EPID images

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, Brian W.; Greer, Peter B.; School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, New South Wales 2308

2013-07-15

Purpose: To develop a method for removing the support arm backscatter from images acquired using current Varian electronic portal imaging devices (EPIDs).Methods: The effect of arm backscatter on EPID images was modeled using a kernel convolution method. The parameters of the model were optimized by comparing on-arm images to off-arm images. The model was used to develop a method to remove the effect of backscatter from measured EPID images. The performance of the backscatter removal method was tested by comparing backscatter corrected on-arm images to measured off-arm images for 17 rectangular fields of different sizes and locations on the imager.more » The method was also tested using on- and off-arm images from 42 intensity modulated radiotherapy (IMRT) fields.Results: Images generated by the backscatter removal method gave consistently better agreement with off-arm images than images without backscatter correction. For the 17 rectangular fields studied, the root mean square difference of in-plane profiles compared to off-arm profiles was reduced from 1.19% (standard deviation 0.59%) on average without backscatter removal to 0.38% (standard deviation 0.18%) when using the backscatter removal method. When comparing to the off-arm images from the 42 IMRT fields, the mean {gamma} and percentage of pixels with {gamma} < 1 were improved by the backscatter removal method in all but one of the images studied. The mean {gamma} value (1%, 1 mm) for the IMRT fields studied was reduced from 0.80 to 0.57 by using the backscatter removal method, while the mean {gamma} pass rate was increased from 72.2% to 84.6%.Conclusions: A backscatter removal method has been developed to estimate the image acquired by the EPID without any arm backscatter from an image acquired in the presence of arm backscatter. The method has been shown to produce consistently reliable results for a wide range of field sizes and jaw configurations.« less

Locally Motivated GLOBE Investigations - A Key to Success

NASA Astrophysics Data System (ADS)

Washburne, J. C.; Geery, W.

2003-12-01

The GLOBE program was set up to help students make a core set of environmental observations at or near their schools, report their data through the internet to share with other students and scientists, analyze their data both locally and globally, and use this knowledge to form a better understanding of their environment. While the GLOBE program has been successful promoting more meaningful data collection, many of the tools and much of the infrastructure available to schools to synthesize their observations are underused. Schools that integrate GLOBE protocols with locally motivated investigations are more likely to implement the higher-order analysis and synthesis components of the program. Indicators of a successful observational program are things like measurement persistence, high data quality, and regular data. Participation in community forums and student-based research projects are evidence of a successful integrated program. A locally motivated issue allows a school to mold their GLOBE investigations around a multi-faceted question that they have first-hand knowledge of, that is both relevant and engaging to their students, and that can be supported by local expertise. In contrast, many GLOBE investigations are designed around abstract, non-site specific, narrowly focused and externally analyzed questions that limit local involvement and motivation. The main focus of this presentation is a few case histories of successful local investigations that incorporated GLOBE soil and air temperature data-logger measurements. The main example is drawn from Mr. Geery's fifth grade class investigation of why temperature differences exist between a local river bottom area and the school, which is located several kilometers away and 100 meters higher.

Quantitative Ultrasound Imaging Using Acoustic Backscatter Coefficients.

NASA Astrophysics Data System (ADS)

Boote, Evan Jeffery

Current clinical ultrasound scanners render images which have brightness levels related to the degree of backscattered energy from the tissue being imaged. These images offer the interpreter a qualitative impression of the scattering characteristics of the tissue being examined, but due to the complex factors which affect the amplitude and character of the echoed acoustic energy, it is difficult to make quantitative assessments of scattering nature of the tissue, and thus, difficult to make precise diagnosis when subtle disease effects are present. In this dissertation, a method of data reduction for determining acoustic backscatter coefficients is adapted for use in forming quantitative ultrasound images of this parameter. In these images, the brightness level of an individual pixel corresponds to the backscatter coefficient determined for the spatial position represented by that pixel. The data reduction method utilized rigorously accounts for extraneous factors which affect the scattered echo waveform and has been demonstrated to accurately determine backscatter coefficients under a wide range of conditions. The algorithms and procedures used to form backscatter coefficient images are described. These were tested using tissue-mimicking phantoms which have regions of varying scattering levels. Another phantom has a fat-mimicking layer for testing these techniques under more clinically relevant conditions. Backscatter coefficient images were also formed of in vitro human liver tissue. A clinical ultrasound scanner has been adapted for use as a backscatter coefficient imaging platform. The digital interface between the scanner and the computer used for data reduction are described. Initial tests, using phantoms are presented. A study of backscatter coefficient imaging of in vivo liver was performed using several normal, healthy human subjects.

Oil film thickness using airborne laser-induced oil fluorescence backscatter

NASA Technical Reports Server (NTRS)

Hoge, F. E.

1983-01-01

Remote airborne measurement of oil film thickness on ocean surface using laser-induced water Raman backscatter is discussed. It is pointed out that the theoretical model of oil fluorescence by Horvath et al. (1971) contains the necessary constituents to provide for the natural background fluorescence that is also induced by the laser during the course of an oil thickness experiment. How the various parameters of the model are obtained from typical airborne profile data is discussed, and it is shown that the water Raman backscatter may be used to assist further in the application of the data. The regions or water types over which the technique might be most useful or applicable are discussed.

The Fold Analysis Challenge: A virtual globe-based educational resource

NASA Astrophysics Data System (ADS)

De Paor, Declan G.; Dordevic, Mladen M.; Karabinos, Paul; Tewksbury, Barbara J.; Whitmeyer, Steven J.

2016-04-01

We present an undergraduate structural geology laboratory exercise using the Google Earth virtual globe with COLLADA models, optionally including an interactive stereographic projection and JavaScript controls. The learning resource challenges students to identify bedding traces and estimate bedding orientation at several locations on a fold, to fit the fold axis and axial plane to stereographic projection data, and to fit a doubly-plunging fold model to the large-scale structure. The chosen fold is the Sheep Mountain Anticline, a Laramide uplift in the Big Horn Basin of Wyoming. We take an education research-based approach, guiding students through three levels of difficulty. The exercise aims to counter common student misconceptions and stumbling blocks regarding penetrative structures. It can be used in preparation for an in-person field trip, for post-trip reinforcement, or as a virtual field experience in an online-only course. Our KML scripts can be easily transferred to other fold structures around the globe.

Bottom Backscattering Strengths Measured in Shallow and Deep Water

DTIC Science & Technology

2017-01-18

basically the same experimental set up (Fig. 2-1) as the BBS experiments that form the basis of the shallow-water portion of this report1. Their dates...6 experiments in 5 distinct environments from 1993 to 2005. This report presents the BBS results from these experiments , as well as empirical fits...Test Operations…………………………………………………………..50 B Measured Bottom Backscattering Strengths…………………...……..50 7 CROSS- EXPERIMENT EPL-FIT VALUES (SHALLOW

iGlobe Interactive Visualization and Analysis of Spatial Data

NASA Technical Reports Server (NTRS)

Hogan, Patrick

2012-01-01

iGlobe is open-source software built on NASA World Wind virtual globe technology. iGlobe provides a growing set of tools for weather science, climate research, and agricultural analysis. Up until now, these types of sophisticated tools have been developed in isolation by national agencies, academic institutions, and research organizations. By providing an open-source solution to analyze and visualize weather, climate, and agricultural data, the scientific and research communities can more readily advance solutions needed to understand better the dynamics of our home planet, Earth

VRPI Temporal Progression of Closed Globe Injury from Blast Exposure

DTIC Science & Technology

2015-09-01

significant increases in VEGF have been reported in many ocular disorders including diabetic retinopathy , diffuse macular edema, retinal vein...Open globe injury is often readily identifiable and typically undergoes urgent surgical repair. However, closed globe injury may not be detected ...including shrapnel or debris to the eye, is easily identified and rapidly treated. Closed globe trauma may not be detected right away, and little is

A Laboratory Study of the Effect of Frost Flowers on C Band Radar Backscatter from Sea Ice

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Martin, S.; Perovich, D. K.; Kwok, R.; Drucker, R.; Gow, A. J.

1997-01-01

C band images of Arctic sea ice taken by the ERS 1 synthetic aperture radar show transitory regions of enhanced radar backscatter from young sea ice. Published field observations associate this increase with frost flower growth and the capture of blowing snow by the flowers. To investigate the first part of this phenomenon, we carried out a laboratory experiment on the response of C band radar backscatter to frost flowers growing on the surface of newly formed saline ice. The experiment took place in a 5 m by 7 m by 1.2 m deep saline water pool located in a two-story indoor refrigerated facility at the Cold Regions Research and Engineering Laboratory. Sodium chloride ice was grown in this pool at an air temperature of -28 C. The frost flowers first appeared on the ice surface as dendrites and then changed to needles as the ice sheet grew thicker and the surface temperatures became colder. The frost flowers reached to a height of 10-15 mm, and beneath each cluster of frost flowers a slush layer formed to a thickness of approximately 4 mm. Far-field radar measurements of the backscatter from the ice were made at incident angles from 20 to 40 deg and at approximately 6-hour intervals throughout the 3-day period of the experiment. A backscatter minimum occurred early in the flower growth at the time coincident with an abrupt doubling in the ice surface salinity. Once the full flower coverage was achieved, we removed first the crystal flowers and then the slush layer from the ice surface. The results for these cases show that the crystals have little impact on the backscatter, while the underlying slush patches yield a backscatter increase of 3-5 dB over that of bare ice. The laboratory results suggest that this relative backscatter increase of approximately 5 dB can be used as an index to mark the full area coverage of frost flowers.

A Laboratory Study of the Effect of Frost Flowers on C Band Radar Backscatter from Sea Ice

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Martin, S.; Perovich, D. K.; Kwok, R.; Drucker, R.; Gow, A. J.

1997-01-01

C band images of Arctic sea ice taken by the ERS 1 synthetic aperture radar show transitory regions of enhanced radar backscatter from young sea ice. Published field observations associate this increase with frost flower growth and the capture of blowing snow by the flowers. To investigate the first part of this phenomenon, we carried out a laboratory experiment on the response of C band radar backscatter to frost flowers growing on the surface of newly formed saline ice. The experiment took place in a 5 m by 7 m by 1.2 m deep saline water pool located in a two-story indoor refrigerated facility at the Cold Regions Research and Engineering Laboratory. Sodium chloride ice was grown in this pool at an air temperature of -28 C. The frost flowers first appeared on the ice surface as dendrites and then changed to needles as the ice sheet grew thicker and the surface temperatures became colder. The frost flowers reached to a height of 10-15 mm, and beneath each cluster of frost flowers a slush layer formed to a thickness of approximately 4 mm. Far-field radar measurements of the backscatter from the ice were made at incident angles from 20 C to 40 C and at approximately 6-hour intervals throughout the 3-day period of the experiment. A backscatter minimum occurred early in the flower growth at the time coincident with an abrupt doubling in the ice surface salinity. Once the full flower coverage was achieved, we removed first the crystal flowers and then the slush layer from the ice surface. The results for these cases show that the crystals have little impact on the backscatter, while the underlying slush patches yield a backscatter increase of 3-5 dB over that o f bare ice. The laboratory results suggest that this relative backscatter increase of approximately 5 dB can be used as an index to mark the full areal coverage of frost flowers.

Trial-by-fire transformation: an interview with Globe Metallurgical's Arden C. Sims. Interview by Bruce Rayner.

PubMed

Sims, A C

1992-01-01

Globe Metallurgical Inc., a $115 million supplier of specialty metals, is best known as the first small company to win the Baldrige Award in 1988. But there is much more to this gutsy little company than total quality. During the 1980s, Globe transformed itself from a rust-belt has-been on the verge of bankruptcy into a high-technology, high-quality industry leader. Along the way, the company went private in a management-led leveraged buyout, embraced flexible work teams, adopted a high-value-added, niche marketing strategy, and took its business global. Leading the way in Globe's reinvention was Chief Executive Arden C. Sims, the slow-talking son of a West Virginian coal miner. When he joined the company in 1984, Sims had no experience in the new managerial techniques. He was a product of the old school of management: cut costs and trim operations to regain competitiveness. But he soon discovered that old-style management was not enough to battle offshore competitors, an unproductive work force, rising costs, and outdated production technology. He was forced to go looking for new ideas and practices. In a succession of learning experiences, Sims attended a seminar on total quality in 1985, paving the way for the company's quality program; he discovered the power of flexible work teams when management was forced to run the furnaces during a year-long strike; he organized an LBO, allowing him to change the work order even more dramatically; and he took the company global and into highly profitable niche markets by severing a long-standing relationship with Globe's sales and marketing representative. As a result of these and other changes, Globe leads the specialty metals industry in virtually all performance measures.

OceanGLOBE: an Outdoor Research and Environmental Education Program for K-12 Students

NASA Astrophysics Data System (ADS)

Perry, R. B.; Hamner, W. M.

2006-12-01

OceanGLOBE is an outdoor environmental research and education program for upper elementary, middle and high school students, supplemented by online instructional materials that are available without charge to any educator. OceanGLOBE was piloted in 1995 with support from a National Science Foundation Teacher Enhancement project, "Leadership in Marine Science" (award no.ESI-9454413 to UCLA). Continuing support by a second NSF Teacher Enhancement project (award no. ESI-9819424 to UCLA) and by COSEE-West (NSF awards OCE-215506 to UCLA and OCE-0215497 to USC) has enabled OceanGLOBE to expand to a growing number of schools and to provide an increasingly robust collection of marine science instructional materials on its website, http://www.msc.ucla.edu/oceanglobe/ OceanGLOBE provides a mechanism for students to conduct inquiry-based, hands-on marine science research, providing experiences that anchor the national and state science content standards learned in the classroom. Students regularly collect environmental and biological data from a beach site over an extended period of time. In the classroom they organize, graph and analyze their data, which can lead to a variety of student-created science products. Beach research is supported by instructional marine science materials on the OceanGLOBE website. These online materials also can be used in the classroom independent of the field component. Annotated PowerPoint slide shows explain research protocols and provide marine science content. Field guides and photographs of marine organisms (with emphasis on the Southern California Bight) and a growing collection of classroom investigations (applicable to any ocean location) support the science content presented in the beach research program and slide shows. In summary, OceanGLOBE is a comprehensive learning package grounded in hands-on, outdoor marine science research project in which students are the principal investigators. By doing scientific work repetitively over an

Engaging Citizen Scientists across North America to Monitor Eclipse-driven Environmental Change through NASA GLOBE Observer, Results and Lessons Learned

NASA Astrophysics Data System (ADS)

Riebeek Kohl, H.; Weaver, K.; Overoye, D.; Martin, A.; Andersen, T.

2017-12-01

How cool was the eclipse? NASA GLOBE Observer challenged citizen scientists across North America to answer that question by observing temperature and cloud changes throughout the August 2017 Total Solar Eclipse. The experiment was meant to chart the impact of changes in solar energy at Earth's surface across all regions that experienced the eclipse, both partial and total. Citizen scientists reported air temperature every 5-10 minutes from first contact to last contact through the free GLOBE Observer app. They also reported cloud cover and cloud type every 15-30 minutes or as changes happened as a proxy for changes in the atmosphere. No data were collected during totality, as we wanted citizen scientists to focus on the eclipse at that time. To recruit citizen scientists, members of the GLOBE Observer Team participated in six large outreach events across the path of totality. We also encouraged participation outside the path of totality though partnerships with informal education institutions and direct communication to the public through NASA communication channels. This presentation will report statistics on citizen science participation and lessons learned about citizen science as an outreach tool. Did participation in the experiment enhance a person's eclipse experience? Did citizen scientists find enough value in the experiment to continue to participate in GLOBE Observer, a long-term citizen science program, after the eclipse? We will also present early results of observed temperature and cloud changes.

A Review of Global Learning & Observations to Benefit the Environment (GLOBE)

ERIC Educational Resources Information Center

Executive Office of the President, 2010

2010-01-01

The Global Learning and Observations to Benefit the Environment (GLOBE) program is a worldwide, hands-on, primary and secondary school-based science and education program. GLOBE supports students, teachers, and scientists in collaborations using inquiry-based investigations of the environment and the earth system. GLOBE currently works in close…

Modeling the wet bulb globe temperature using standard meteorological measurements.

PubMed

Liljegren, James C; Carhart, Richard A; Lawday, Philip; Tschopp, Stephen; Sharp, Robert

2008-10-01

The U.S. Army has a need for continuous, accurate estimates of the wet bulb globe temperature to protect soldiers and civilian workers from heat-related injuries, including those involved in the storage and destruction of aging chemical munitions at depots across the United States. At these depots, workers must don protective clothing that increases their risk of heat-related injury. Because of the difficulty in making continuous, accurate measurements of wet bulb globe temperature outdoors, the authors have developed a model of the wet bulb globe temperature that relies only on standard meteorological data available at each storage depot for input. The model is composed of separate submodels of the natural wet bulb and globe temperatures that are based on fundamental principles of heat and mass transfer, has no site-dependent parameters, and achieves an accuracy of better than 1 degree C based on comparisons with wet bulb globe temperature measurements at all depots.

Snowcover influence on backscattering from terrain

NASA Technical Reports Server (NTRS)

Ulaby, F. T.; Abdelrazik, M.; Stiles, W. H.

1984-01-01

The effects of snowcover on the microwave backscattering from terrain in the 8-35 GHz region are examined through the analysis of experimental data and by application of a semiempirical model. The model accounts for surface backscattering contributions by the snow-air and snow-soil interfaces, and for volume backscattering contributions by the snow layer. Through comparisons of backscattering data for different terrain surfaces measured both with and without snowcover, the masking effects of snow are evaluated as a function of snow water equivalent and liquid water content. The results indicate that with dry snowcover it is not possible to discriminate between different types of ground surface (concrete, asphalt, grass, and bare ground) if the snow water equivalent is greater than about 20 cm (or a depth greater than 60 cm for a snow density of 0.3 g/cu cm). For the same density, however, if the snow is wet, a depth of 10 cm is sufficient to mask the underlying surface.

Science Outreach in Virtual Globes; Best Practices

NASA Astrophysics Data System (ADS)

Treves, R. W.

2007-12-01

The popularity of projects such as 'Crisis in Darfur' and the IPY (International Polar Year) network link show the potential of using the rich functionality of Virtual Globes for science outreach purposes. However, the structure of outreach projects in Virtual Globes varies widely. Consider an analogy: If you pick up a science journal you immediately know where to find the contents page and what the title and cover story are meant to communicate. That is because journals have a well defined set of norms that they follow in terms of layout and design. Currently, science projects presented in virtual globes have, at best, weakly defined norms, there are little common structural elements beyond those imposed by the constraints of the virtual globe system. This is not a criticism of the science community, it is to be expected since norms take time to develop for any new technology. An example of the development of norms are pages on the web: when they first started appearing structure was unguided but over the last few years structural elements such as a left hand side navigation system and a bread crumb trail near the header have become common. In this paper I shall describe the developing norms of structure I have observed in one area of virtual globe development; Google Earth science outreach projects. These norms include text introductions, video introductions, use of folders and overlay presentation. I shall go on to examine how best to use these norms to build a clear and engaging outreach project and describe some cartographic best practices that we should also consider adopting as norms. I also will briefly explain why I think norms in science outreach aid creativity rather than limiting it despite the counter intuitive nature of this concept.

Interlinking backscatter, grain size and benthic community structure

NASA Astrophysics Data System (ADS)

McGonigle, Chris; Collier, Jenny S.

2014-06-01

The relationship between acoustic backscatter, sediment grain size and benthic community structure is examined using three different quantitative methods, covering image- and angular response-based approaches. Multibeam time-series backscatter (300 kHz) data acquired in 2008 off the coast of East Anglia (UK) are compared with grain size properties, macrofaunal abundance and biomass from 130 Hamon and 16 Clamshell grab samples. Three predictive methods are used: 1) image-based (mean backscatter intensity); 2) angular response-based (predicted mean grain size), and 3) image-based (1st principal component and classification) from Quester Tangent Corporation Multiview software. Relationships between grain size and backscatter are explored using linear regression. Differences in grain size and benthic community structure between acoustically defined groups are examined using ANOVA and PERMANOVA+. Results for the Hamon grab stations indicate significant correlations between measured mean grain size and mean backscatter intensity, angular response predicted mean grain size, and 1st principal component of QTC analysis (all p < 0.001). Results for the Clamshell grab for two of the methods have stronger positive correlations; mean backscatter intensity (r2 = 0.619; p < 0.001) and angular response predicted mean grain size (r2 = 0.692; p < 0.001). ANOVA reveals significant differences in mean grain size (Hamon) within acoustic groups for all methods: mean backscatter (p < 0.001), angular response predicted grain size (p < 0.001), and QTC class (p = 0.009). Mean grain size (Clamshell) shows a significant difference between groups for mean backscatter (p = 0.001); other methods were not significant. PERMANOVA for the Hamon abundance shows benthic community structure was significantly different between acoustic groups for all methods (p ≤ 0.001). Overall these results show considerable promise in that more than 60% of the variance in the mean grain size of the Clamshell grab

Virtual Globes, where we were, are and will be

NASA Astrophysics Data System (ADS)

Dehn, J.; Webley, P. W.; Worden, A. K.

2016-12-01

Ten years ago, Google Earth was new, and the first "Virtual Globes" session was held at AGU. Only a few of us realized the potential of this technology at the time, but the idea quickly caught on. At that time a virtual globe came in two flavors, first a complex GIS system that was utterly impenetrable for the public, or a more accessible version with limited functionality and layers that was available on a desktop computer with a good internet connection. Google Earth's use of the Keyhole Markup Language opened the door for scientists and the public to share data and visualizations across disciplines and revolutionized how everyone uses geographic data. In the following 10 years, KML became more advanced, virtual globes moved to mobile and handheld platforms, and the Google Earth engine allowed for more complex data sharing among scientists. Virtual globe images went from a rare commodity to being everywhere in our lives, from weather forecasts, in our cars, on our smart-phones and shape how we receive and process data. This is a fantastic tool for education and with newer technologies can reach the the remote corners of the world and developing countries. New and emerging technologies allow for augmented reality to be merged with the globes, and for real-time data integration with sensors built into mobile devices or add-ons. This presentation will follow the history of virtual globes in the geosciences, show how robust technologies can be used in the field and classroom today, and make some suggestions for the future.

SAR backscatter from coniferous forest gaps

NASA Technical Reports Server (NTRS)

Day, John L.; Davis, Frank W.

1992-01-01

A study is in progress comparing Airborne Synthetic Aperture Radar (AIRSAR) backscatter from coniferous forest plots containing gaps to backscatter from adjacent gap-free plots. Issues discussed are how do gaps in the range of 400 to 1600 sq m (approximately 4-14 pixels at intermediate incidence angles) affect forest backscatter statistics and what incidence angles, wavelengths, and polarizations are most sensitive to forest gaps. In order to visualize the slant-range imaging of forest and gaps, a simple conceptual model is used. This strictly qualitative model has led us to hypothesize that forest radar returns at short wavelengths (eg., C-band) and large incidence angles (e.g., 50 deg) should be most affected by the presence of gaps, whereas returns at long wavelengths and small angles should be least affected. Preliminary analysis of 1989 AIRSAR data from forest near Mt. Shasta supports the hypothesis. Current forest backscatter models such as MIMICS and Santa Barbara Discontinuous Canopy Backscatter Model have in several cases correctly predicted backscatter from forest stands based on inputs of measured or estimated forest parameters. These models do not, however, predict within-stand SAR scene texture, or 'intrinsic scene variability' as Ulaby et al. has referred to it. For instance, the Santa Barbara model, which may be the most spatially coupled of the existing models, is not truly spatial. Tree locations within a simulated pixel are distributed according to a Poisson process, as they are in many natural forests, but tree size is unrelated to location, which is not the case in nature. Furthermore, since pixels of a simulated stand are generated independently in the Santa Barbara model, spatial processes larger than one pixel are not modeled. Using a different approach, Oliver modeled scene texture based on an hypothetical forest geometry. His simulated scenes do not agree well with SAR data, perhaps due to the simple geometric model used. Insofar as texture

The angular distribution of diffusely backscattered light

NASA Astrophysics Data System (ADS)

Vera, M. U.; Durian, D. J.

1997-03-01

The diffusion approximation predicts the angular distribution of light diffusely transmitted through an opaque slab to depend only on boundary reflectivity, independent of scattering anisotropy, and this has been verified by experiment(M.U. Vera and D.J. Durian, Phys. Rev. E 53) 3215 (1996). Here, by contrast, we demonstrate that the angular distribution of diffusely backscattered light depends on scattering anisotropy as well as boundary reflectivity. To model this observation scattering anisotropy is added to the diffusion approximation by a discontinuity in the photon concentration at the source point that is proportional to the average cosine of the scattering angle. We compare the resulting predictions with random walk simulations and with measurements of diffusely backscattered intensity versus angle for glass frits and aqueous suspensions of polystyrene spheres held in air or immersed in a water bath. Increasing anisotropy and boundary reflectivity each tend to flatten the predicted distributions, and for different combinations of anisotropy and reflectivity the agreement between data and predictions ranges from qualitatively to quantitatively good.

Unfolding Leonardo DA Vinci's Globe (ad 1504) to Reveal its Historical World Map

NASA Astrophysics Data System (ADS)

Verhoeven, G. J.; Missinne, S. J.

2017-08-01

This paper reports in detail on the image-based modelling and unwrapping approach used to create a two-dimensional projected map of an astonishing ostrich egg globe from AD 1504. This miniature egg globe is not only the oldest extant engraved globe, but it is also the oldest post-Columbian globe of the world and the first ever to depict Newfoundland and many other territories. The intention of digitally recording the surface geometry and colour of this unique artefact was to portray the original layout of the world map used by the Florentine Renaissance artist to make this globe. In addition, it was expected to substantiate iconographical details, which are hard to study at its scale of 1:80,000,000. The ostrich egg globe is the prototype of the Lenox Globe kept at the New York Public Library. The latter is very beneficial to examine how the egg globe looked like before being glued together at its equator. On the other hand, unfolding the map engraved in the ostrich egg halves enables a more detailed study of the remarkable details visible on both globes, since the engravings on the quasi-white egg surface are much easier to discern than those of the highly reflective red copper Lenox Globe. Finally, a detailed study of the unwrapped 3D surface is essential to learn more about the world vision of its creator and the incredible efforts that went into making this globe. Thanks to some particular pictographic details as well as the way in which the engravings are applied (by a left-handed person), the globe artist can be identified as Leonardo da Vinci.

Backscatter correction factor for megavoltage photon beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Yida; Zhu, Timothy C.

2011-10-15

Purpose: For routine clinical dosimetry of photon beams, it is often necessary to know the minimum thickness of backscatter phantom material to ensure that full backscatter condition exists. Methods: In case of insufficient backscatter thickness, one can determine the backscatter correction factor, BCF(s,d,t), defined as the ratio of absorbed dose measured on the central-axis of a phantom with backscatter thickness of t to that with full backscatter for square field size s and forward depth d. Measurements were performed in SAD geometry for 6 and 15 MV photon beams using a 0.125 cc thimble chamber for field sizes between 10more » x 10 and 30 x 30 cm at depths between d{sub max} (1.5 cm for 6 MV and 3 cm for 15 MV) and 20 cm. Results: A convolution method was used to calculate BCF using Monte-Carlo simulated point-spread kernels generated for clinical photon beams for energies between Co-60 and 24 MV. The convolution calculation agrees with the experimental measurements to within 0.8% with the same physical trend. The value of BCF deviates more from 1 for lower energies and larger field sizes. According to our convolution calculation, the minimum BCF occurs at forward depth d{sub max} and 40 x 40 cm field size, 0.970 for 6 MV and 0.983 for 15 MV. Conclusions: The authors concluded that backscatter thickness is 6.0 cm for 6 MV and 4.0 cm for 15 MV for field size up to 10 x 10 cm when BCF = 0.998. If 4 cm backscatter thickness is used, BCF is 0.997 and 0.983 for field size of 10 x 10 and 40 x 40 cm for 6 MV, and is 0.998 and 0.990 for 10 x 10 and 40 x 40 cm for 15 MV, respectively.« less

Seeing Stars: A GLOBE at Night Campaign Update

NASA Astrophysics Data System (ADS)

Walker, Constance E.; Pompea, S. M.; Sparks, R. T.; Newhouse, M.

2012-01-01

The emphasis in the international citizen-science, star-hunting campaign, GLOBE at Night, is in bringing awareness to the public on issues of light pollution. Light pollution threatens not only observatory sites and our "right to starlight", but can affect energy consumption, wildlife and health. GLOBE at Night has successfully reached a few 100,000 citizen-scientists. What has done in the last year to contribute to its success? • To promote the campaign via popular social media, GLOBE at Night created Facebook and Twitter pages. • Videos have been created for 4 out of 8 Dark Skies Rangers activities. • Sky brightness measurements can be submitted in real time with smart phones or tablets using the new Web application at www.globeatnight.org/webapp/. The location, date and time register automatically. • As a proto-type, an adopt-a-street program had people in Tucson take measurements every mile for the length of the street. Grid measurements canvassed the town, allowing for comparisons of light levels over time. • The increase to 2 campaigns in 2011 re-enforces these studies. In 2012, the campaign will be offered 4 times for 10 days a month: January 14-23, February 12-21, March 13-22 and April 11-20. • A new Web application (www.globeatnight.org/mapapp/) allows for mapping GLOBE at Night data points within a specified distance around a city or area of choice. The resulting maps are bookmarkable and shareable. • NOAO and Arizona Game and Fish Department started a project with GLOBE at Night data and bat telemetry to examine a dark skies corridor in Tucson where endangered bats fly. While providing these updates to the GLOBE at Night program, the presentation will highlight the education and outreach value of the program's resources and outcomes, lessons learned, successes and pitfalls in communicating awareness with the public and attracting young people to study science.

GLOBE Cornerstones: Advancing Student Research Worldwide through Virtual and Regional Symposia

NASA Astrophysics Data System (ADS)

Bourgeault, J.; Malmberg, J. S.; Murphy, T.; Darche, S.; Ruscher, P.; Jabot, M.; Odell, M. R. L.; Kennedy, T.

2016-12-01

The GLOBE Program, an international science and education program, encourages students from around the world to participate in authentic scientific research of the Earth system. Students use scientific protocols to explore their local environments, compare their findings with other GLOBE schools both in the U.S. and in other participating countries, and then share their findings via the GLOBE.gov website. In order to facilitate this scientific communication, GLOBE held an international virtual science fair in 2016. The science fair included 105 research projects submitted from GLOBE students in various countries, 37 mentoring scientists, and 24 judges. Mentors and judges were members of the GLOBE International STEM Professionals Network and located around the world. On a national level, NSF funded six face-to-face U.S. regional student research symposia where 164 students presented 67 research projects to scientists for review. The 1.5 day events included student activities, teacher professional development, tours of NASA centers, and opportunities for students to engage with scientists to discover both traditional and non-traditional STEM career pathways. To support teachers, the leadership team offered and archived webinars on science practices; from field investigation basics to creating a poster and GLOBE partners provided guidance along the way. This presentation will include the framework for the regional and international science symposia , the scoring rubrics and evaluation, recruitment of judges and mentors, and lessons learned.

Laissez-Faire : Fully Asymmetric Backscatter Communication

PubMed Central

Hu, Pan; Zhang, Pengyu; Ganesan, Deepak

2016-01-01

Backscatter provides dual-benefits of energy harvesting and low-power communication, making it attractive to a broad class of wireless sensors. But the design of a protocol that enables extremely power-efficient radios for harvesting-based sensors as well as high-rate data transfer for data-rich sensors presents a conundrum. In this paper, we present a new fully asymmetric backscatter communication protocol where nodes blindly transmit data as and when they sense. This model enables fully flexible node designs, from extraordinarily power-efficient backscatter radios that consume barely a few micro-watts to high-throughput radios that can stream at hundreds of Kbps while consuming a paltry tens of micro-watts. The challenge, however, lies in decoding concurrent streams at the reader, which we achieve using a novel combination of time-domain separation of interleaved signal edges, and phase-domain separation of colliding transmissions. We provide an implementation of our protocol, LF-Backscatter, and show that it can achieve an order of magnitude or more improvement in throughput, latency and power over state-of-art alternatives. PMID:28286885

Atmospheric Backscatter Model Development for CO Sub 2 Wavelengths

NASA Technical Reports Server (NTRS)

Deepak, A.; Kent, G.; Yue, G. K.

1982-01-01

The results of investigations into the problems of modeling atmospheric backscatter from aerosols, in the lowest 20 km of the atmosphere, at CO2 wavelengths are presented, along with a summary of the relevant aerosol characteristics and their variability, and a discussion of the measurement techniques and errors involved. The different methods of calculating the aerosol backscattering function, both from measured aerosol characteristics and from optical measurements made at other wavelengths, are discussed in detail, and limits are placed on the accuracy of these methods. The effects of changing atmospheric humidity and temperature on the backscatter are analyzed and related to the actual atmosphere. Finally, the results of modeling CO2 backscatter in the atmosphere are presented and the variation with height and geographic location discussed, and limits placed on the magnitude of the backscattering function. Conclusions regarding modeling techniques and modeled atmospheric backscatter values are presented in tabular form.

3D Backscatter Imaging System

NASA Technical Reports Server (NTRS)

Whitaker, Ross (Inventor); Turner, D. Clark (Inventor)

2016-01-01

Systems and methods for imaging an object using backscattered radiation are described. The imaging system comprises both a radiation source for irradiating an object that is rotationally movable about the object, and a detector for detecting backscattered radiation from the object that can be disposed on substantially the same side of the object as the source and which can be rotationally movable about the object. The detector can be separated into multiple detector segments with each segment having a single line of sight projection through the object and so detects radiation along that line of sight. Thus, each detector segment can isolate the desired component of the backscattered radiation. By moving independently of each other about the object, the source and detector can collect multiple images of the object at different angles of rotation and generate a three dimensional reconstruction of the object. Other embodiments are described.

X-ray backscatter imaging of nuclear materials

DOEpatents

Chapman, Jeffrey Allen; Gunning, John E; Hollenbach, Daniel F; Ott, Larry J; Shedlock, Daniel

2014-09-30

The energy of an X-ray beam and critical depth are selected to detect structural discontinuities in a material having an atomic number Z of 57 or greater. The critical depth is selected by adjusting the geometry of a collimator that blocks backscattered radiation so that backscattered X-ray originating from a depth less than the critical depth is not detected. Structures of Lanthanides and Actinides, including nuclear fuel rod materials, can be inspected for structural discontinuities such as gaps, cracks, and chipping employing the backscattered X-ray.

Rotating Globe of Ganymede Geology

NASA Image and Video Library

2014-02-12

This is a frame from an animation of a rotating globe of Jupiter moon Ganymede, with a geologic map superimposed over a global color mosaic, incorporating the best available imagery from NASA Voyager 1 and 2 spacecraft, and Galileo spacecraft.

A microwave backscattering model for precipitation

NASA Astrophysics Data System (ADS)

Ermis, Seda

A geophysical microwave backscattering model for space borne and ground-based remote sensing of precipitation is developed and used to analyze backscattering measurements from rain and snow type precipitation. Vector Radiative Transfer (VRT) equations for a multilayered inhomogeneous medium are applied to the precipitation region for calculation of backscattered intensity. Numerical solution of the VRT equation for multiple layers is provided by the matrix doubling method to take into account close range interactions between particles. In previous studies, the VRT model was used to calculate backscattering from a rain column on a sea surface. In the model, Mie scattering theory for closely spaced scatterers was used to determine the phase matrix for each sublayer characterized by a set of parameters. The scatterers i.e. rain drops within the sublayers were modelled as spheres with complex permittivities. The rain layer was bounded by rough boundaries; the interface between the cloud and the rain column as well as the interface between the sea surface and the rain were all analyzed by using the integral equation model (IEM). Therefore, the phase matrix for the entire rain column was generated by the combination of surface and volume scattering. Besides Mie scattering, in this study, we use T-matrix approach to examine the effect of the shape to the backscattered intensities since larger raindrops are most likely oblique in shape. Analyses show that the effect of obliquity of raindrops to the backscattered wave is related with size of the scatterers and operated frequency. For the ground-based measurement system, the VRT model is applied to simulate the precipitation column on horizontal direction. Therefore, the backscattered reflectivities for each unit range of volume are calculated from the backscattering radar cross sections by considering radar range and effective illuminated area of the radar beam. The volume scattering phase matrices for each range interval

Mars Orbiter Laser Altimiter (MOLA) Globe

NASA Technical Reports Server (NTRS)

2000-01-01

The color shaded relief image used as the base for this globe has a resolution of 32 pixels per degree (approximately 1850 m/pixel), and was produced and supplied by the MOLA Science Team (http://ltpwww.gsfc.nasa.gov/tharsis/mola.html). The image is shaded as if illuminated everywhere from the west. The elevations represented in color are with respect to a gravitational equipotential surface whose mean equatorial radius is that of the topography. The Astrogeology Team of the U.S. Geological Survey reprojected the image into the format displayed above.

The images are presented in a projection that portrays the entire surface of Mars in a manner suitable for the production of a globe; the number, size, and placement of text annotations were chosen for a 12-inch globe. Prominent features are labeled with names approved by the International Astronomical Union. A specialized program was used to create the 'flower petal' appearance of the images; the area of each petal from 0 to 75 degrees latitude is in the Transverse Mercator projection, and the area from 75 to 90 degrees latitude is in the Lambert Azimuthal Equal-Area projection. The northern hemisphere of Mars is shown on the left, and the southern hemisphere on the right.

Shedding Light on Light Pollution: Reports from GLOBE at Night

NASA Astrophysics Data System (ADS)

Walker, Constance E.; Pompea, S. M.; Isbell, D.

2009-05-01

The citizen-science program on light pollution, GLOBE at Night, has had rich responses during this year's campaign in March 2009. Reporting on some of the highlights, we will hear success stories and lessons learned from educators, students, science centers and astronomy clubs from around the world. Communities will be featured from several cities, such Norman, Oklahoma, Mishawaka, Indiana, Willimantic, Connecticut, and Waynesville, Ohio, which created mini-campaigns that combined local students with public advocates and representatives from local city and county governments. Connecticut kids collaborated with students in Wales, Canada and Romania on GLOBE at Night, and an extensive campaign was planned with the schools near the observatories of north-central Chile. Groups that have received special training in GLOBE at Night and related activities include the "Astronomy from the Ground Up” network of science and nature centers (fostered by the ASP and the NSF), 146 amateur astronomers who are part of the ASP-NASA Night-Sky Network, and the Association of Science-Technology Centers. Special training was given over forums, telecon-powerpoint presentations and blogs, to fit the needs of the communities. Among the more interesting media efforts for the general public, GLOBE at Night was the topic of the March 6 episode of the IYA2009 "Days of Astronomy" podcast. International organizing efforts for GLOBE at Night have been strong in countries like Argentina, Australia, Austria, Brazil, Canada, Chile, Costa Rica, the Czech Republic, Germany, Hungary, Ireland, Poland, Portugal, Romania, Spain and the United Kingdom, to name a few. We will also discuss how cities, such as Tucson, Arizona, combined efforts on GLOBE at Night with involvement in the World Wildlife Fund's Earth Hour event (www.earthhour.org). Earth Hour encouraged everyone to turn out their lights from 8:30-9:30 p.m. local time on Saturday, March 28, the final night of GLOBE at Night 2009.

Observations of HF backscatter decay rates from HAARP generated FAI

NASA Astrophysics Data System (ADS)

Bristow, William; Hysell, David

2016-07-01

Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

Observations of HF backscatter decay rates from HAARP generated FAI

NASA Astrophysics Data System (ADS)

Bristow, W. A.; Hysell, D. L.

2016-12-01

Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

Mode-converted diffuse ultrasonic backscatter.

PubMed

Hu, Ping; Kube, Christopher M; Koester, Lucas W; Turner, Joseph A

2013-08-01

Diffuse ultrasonic backscatter describes the scattering of elastic waves from interfaces within heterogeneous materials. Previously, theoretical models have been developed for the diffuse backscatter of longitudinal-to-longitudinal (L-L) wave scattering within polycrystalline materials. Following a similar formalism, a mode-conversion scattering model is presented here to quantify the component of an incident longitudinal wave that scatters and is converted to a transverse (shear) wave within a polycrystalline sample. The model is then used to fit experimental measurements associated with a pitch-catch transducer configuration performed using a sample of 1040 steel. From these measurements, an average material correlation length is determined. This value is found to be in agreement with results from L-L scattering measurements and is on the order of the grain size as determined from optical micrographs. Mode-converted ultrasonic backscatter is influenced much less by the front-wall reflection than an L-L measurement and it provides additional microstructural information that is not accessible in any other manner.

Visualization on the Day Night Year Globe

NASA Astrophysics Data System (ADS)

Božić, Mirjana; Vušković, Leposava; Popović, Svetozar; Popović, Jelena; Marković-Topalović, Tatjana

2016-11-01

The story about a properly oriented outdoor globe in the hands and minds of Eratosthenes, Jefferson, Milanković and science educators is presented. Having the same orientation in space as the Earth, the Day Night Year Globe (DING) shows in real time the pattern of illumination of the Earth’s surface and its diurnal and seasonal variations. It is an ideal object for the visualization of knowledge and increase in knowledge about: the form of the Earth, Earth’s rotation, Earth’s revolution around the Sun, the length of seasons, solstices, equinoxes, the longitude problem, the distribution of the Sun’s radiation over the Earth, the impact of this radiation on Earth’s climate, and how to use it efficiently. By attaching a movable vane to the poles, or adding pins around the equator to read time, DING becomes a spherical/globe-shaped sundial. So, the DING is simultaneously useful for teaching physics, geophysics, astronomy, use of solar energy and promoting an inquiry-based learning environment for students and the public.

A web-system of virtual morphometric globes

NASA Astrophysics Data System (ADS)

Florinsky, Igor; Garov, Andrei; Karachevtseva, Irina

2017-04-01

Virtual globes — programs implementing interactive three-dimensional (3D) models of planets — are increasingly used in geo- and planetary sciences. We develop a web-system of virtual morphometric globes. As the initial data, we used the following global digital elevation models (DEMs): (1) a DEM of the Earth extracted from SRTM30_PLUS database; (2) a DEM of Mars extracted from the Mars Orbiter Laser Altimeter (MOLA) gridded data record archive; and (3) A DEM of the Moon extracted from the Lunar Orbiter Laser Altimeter (LOLA) gridded data record archive. From these DEMs, we derived global digital models of the following 16 local, nonlocal, and combined morphometric variables: horizontal curvature, vertical curvature, mean curvature, Gaussian curvature, minimal curvature, maximal curvature, unsphericity curvature, difference curvature, vertical excess curvature, horizontal excess curvature, ring curvature, accumulation curvature, catchment area, dispersive area, topographic index, and stream power index (definitions, formulae, and interpretations can be found elsewhere [1]). To calculate local morphometric variables, we applied a finite-difference method intended for spheroidal equal angular grids [1]. Digital models of a nonlocal and combined morphometric variables were derived by a method of Martz and de Jong adapted to spheroidal equal angular grids [1]. DEM processing was performed in the software LandLord [1]. The calculated morphometric models were integrated into the testing version of the system. The following main functions are implemented in the system: (1) selection of a celestial body; (2) selection of a morphometric variable; (3) 2D visualization of a calculated global morphometric model (a map in equirectangular projection); (4) 3D visualization of a calculated global morphometric model on the sphere surface (a globe by itself); (5) change of a globe scale (zooming); and (6) globe rotation by an arbitrary angle. The testing version of the system

Quantification of Posterior Globe Flattening: Methodology Development and Validationc

NASA Technical Reports Server (NTRS)

Lumpkins, S. B.; Garcia, K. M.; Sargsyan, A. E.; Hamilton, D. R.; Berggren, M. D.; Antonsen, E.; Ebert, D.

2011-01-01

Microgravity exposure affects visual acuity in a subset of astronauts, and mechanisms may include structural changes in the posterior globe and orbit. Particularly, posterior globe flattening has been implicated in several astronauts. This phenomenon is known to affect some terrestrial patient populations, and has been shown to be associated with intracranial hypertension. It is commonly assessed by magnetic resonance imaging (MRI), computed tomography (CT), or B-mode ultrasound (US), without consistent objective criteria. NASA uses a semi-quantitative scale of 0-3 as part of eye/orbit MRI and US analysis for occupational monitoring purposes. The goal of this study was to initiate development of an objective quantification methodology for posterior globe flattening.

Quantification of Posterior Globe Flattening: Methodology Development and Validation

NASA Technical Reports Server (NTRS)

Lumpkins, Sarah B.; Garcia, Kathleen M.; Sargsyan, Ashot E.; Hamilton, Douglas R.; Berggren, Michael D.; Ebert, Douglas

2012-01-01

Microgravity exposure affects visual acuity in a subset of astronauts and mechanisms may include structural changes in the posterior globe and orbit. Particularly, posterior globe flattening has been implicated in the eyes of several astronauts. This phenomenon is known to affect some terrestrial patient populations and has been shown to be associated with intracranial hypertension. It is commonly assessed by magnetic resonance imaging (MRI), computed tomography (CT) or B-mode Ultrasound (US), without consistent objective criteria. NASA uses a semiquantitative scale of 0-3 as part of eye/orbit MRI and US analysis for occupational monitoring purposes. The goal of this study was ot initiate development of an objective quantification methodology to monitor small changes in posterior globe flattening.

The effect of artificial rain on backscattered acoustic signal: first measurements

NASA Astrophysics Data System (ADS)

Titchenko, Yuriy; Karaev, Vladimir; Meshkov, Evgeny; Goldblat, Vladimir

The problem of rain influencing on a characteristics of backscattered ultrasonic and microwave signal by water surface is considered. The rain influence on backscattering process of electromagnetic waves was investigated in laboratory and field experiments, for example [1-3]. Raindrops have a significant impact on backscattering of microwave and influence on wave spectrum measurement accuracy by string wave gauge. This occurs due to presence of raindrops in atmosphere and modification of the water surface. For measurements of water surface characteristics during precipitation we propose to use an acoustic system. This allows us obtaining of the water surface parameters independently on precipitation in atmosphere. The measurements of significant wave height of water surface using underwater acoustical systems are well known [4, 5]. Moreover, the variance of orbital velocity can be measure using these systems. However, these methods cannot be used for measurements of slope variance and the other second statistical moments of water surface that required for analyzing the radar backscatter signal. An original design Doppler underwater acoustic wave gauge allows directly measuring the surface roughness characteristics that affect on electromagnetic waves backscattering of the same wavelength [6]. Acoustic wave gauge is Doppler ultrasonic sonar which is fixed near the bottom on the floating disk. Measurements are carried out at vertically orientation of sonar antennas towards water surface. The first experiments were conducted with the first model of an acoustic wave gauge. The acoustic wave gauge (8 mm wavelength) is equipped with a transceiving antenna with a wide symmetrical antenna pattern. The gauge allows us to measure Doppler spectrum and cross section of backscattered signal. Variance of orbital velocity vertical component can be retrieved from Doppler spectrum with high accuracy. The result of laboratory and field experiments during artificial rain is presented

Light Pollution Awareness through Globe at Night & IYL2015

NASA Astrophysics Data System (ADS)

Walker, Constance E.

2015-01-01

The International Astronomical Union (IAU) will be coordinating extensive activities to raise awareness of light pollution through running the Cosmic Light theme of the International Year of Light (IYL2015) and by partnering in particular with the popular Globe at Night program.Globe at Night (www.globeatnight.org) is an international campaign to raise public awareness of the impact of light pollution by having people measure night-sky brightness and submit observations in real-time with smart phone or later with a computer. In 2015, Globe at Night will run for 10-nights each month, an hour after sunset til before the Moon rises. Students can use the data to monitor levels of light pollution around the world, as well as understand light pollution's effects on energy consumption, plants, wildlife, human health and our ability to enjoy a starry night sky.Since its inception in 2006, more than 115,000 measurements from 115 countries have been reported. The last 9 years of data can be explored with Globe at Night's interactive world map or with the 'map app' to view a particular area. A spreadsheet of the data is downloadable from any year. One can compare Globe at Night data with a variety of other databases to see, for example, how light pollution affects the foraging habits of bats.To encourage public participation in Globe at Night during IYL2015, each month will target an area of the world that habitually contributes during that time. Special concerns for how light pollution affects that area and solutions will be featured on the Globe at Night website (www.globeatnight.org), through its Facebook page, in its newsletter or in the 365DaysofAstronomy.org podcasts.Twice during IYL there will be a global Flash Mob event, one on Super Pi Day (March 14, 2015) and a second in mid-September, where the public will be invited to take night-sky brightness measurements en masse. In April, the International Dark-Sky Week hosted by the International Dark-Sky Association will be

Analysis of the Viscoelastic Properties of the Human Cornea Using Scheimpflug Imaging in Inflation Experiment of Eye Globes

PubMed Central

Lombardo, Giuseppe; Serrao, Sebastiano; Rosati, Marianna; Lombardo, Marco

2014-01-01

Purpose To demonstrate a Scheimpflug-based imaging procedure for investigating the depth- and time-dependent strain response of the human cornea to inflation testing of whole eye globes. Methods Six specimens, three of which with intact corneal epithelium, were mounted in a customized apparatus within a humidity and temperature-monitored wet chamber. Each specimen was subjected to two mechanical tests in order to measure corneal strain resulting from application of cyclic (cyclic regimen) and constant (creep regimen) stress by changing the intra-ocular pressure (IOP) within physiological ranges (18–42 mmHg). Corneal shape changes were analyzed as a function of IOP and both corneal stress-strain curves and creep curves were generated. Results The procedure was highly accurate and repeatable. Upon cyclic stress application, a biomechanical corneal elasticity gradient was found in the front-back direction. The average Young's modulus of the anterior cornea ranged between 2.28±0.87 MPa and 3.30±0.90 MPa in specimens with and without intact epithelium (P = 0.05) respectively. The Young's modulus of the posterior cornea was on average 0.21±0.09 MPa and 0.17±0.06 MPa (P>0.05) respectively. The time-dependent strain response of the cornea to creep testing was quantified by fitting data to a modified Zener model for extracting both the relaxation time and compliance function. Conclusion Cyclic and creep mechanical tests are valuable for investigating the strain response of the intact human cornea within physiological IOP ranges, providing meaningful results that can be translated to clinic. The presence of epithelium influences the results of anterior corneal shape changes when monitoring deformation via Scheimpflug imaging in inflation experiments of whole eye globes. PMID:25397674

An energy-dependent electron backscattering coefficient

NASA Astrophysics Data System (ADS)

Williamson, W., Jr.; Antolak, A. J.; Meredith, R. J.

1987-05-01

An energy-dependent electron backscattering coefficient is derived based on the continuous slowing down approximation and the Bethe stopping power. Backscattering coefficients are given for 10-50-keV electrons incident on bulk and thin-film aluminum, silver, and gold targets. The results are compared with the Everhart theory and empirical fits to experimental data. The energy-dependent theory agrees better with experimental work.

Interaction-induced backscattering in short quantum wires

DOE PAGES

Rieder, M. -T.; Micklitz, T.; Levchenko, A.; ...

2014-10-06

We study interaction-induced backscattering in clean quantum wires with adiabatic contacts exposed to a voltage bias. Particle backscattering relaxes such systems to a fully equilibrated steady state only on length scales exponentially large in the ratio of bandwidth of excitations and temperature. Here in this paper we focus on shorter wires in which full equilibration is not accomplished. Signatures of relaxation then are due to backscattering of hole excitations close to the band bottom which perform a diffusive motion in momentum space while scattering from excitations at the Fermi level. This is reminiscent to the first passage problem of amore » Brownian particle and, regardless of the interaction strength, can be described by an inhomogeneous Fokker-Planck equation. From general solutions of the latter we calculate the hole backscattering rate for different wire lengths and discuss the resulting length dependence of interaction-induced correction to the conductance of a clean single channel quantum wire.« less

Effects of fatty infiltration in human livers on the backscattered statistics of ultrasound imaging.

PubMed

Wan, Yung-Liang; Tai, Dar-In; Ma, Hsiang-Yang; Chiang, Bing-Hao; Chen, Chin-Kuo; Tsui, Po-Hsiang

2015-06-01

Ultrasound imaging has been widely applied to screen fatty liver disease. Fatty liver disease is a condition where large vacuoles of triglyceride fat accumulate in liver cells, thereby altering the arrangement of scatterers and the corresponding backscattered statistics. In this study, we used ultrasound Nakagami imaging to explore the effects of fatty infiltration in human livers on the statistical distribution of backscattered signals. A total of 107 patients volunteered to participate in the experiments. The livers were scanned using a clinical ultrasound scanner to obtain the raw backscattered signals for ultrasound B-mode and Nakagami imaging. Clinical scores of fatty liver disease for each patient were determined according to a well-accepted sonographic scoring system. The results showed that the Nakagami image can visualize the local backscattering properties of liver tissues. The Nakagami parameter increased from 0.62 ± 0.11 to 1.02 ± 0.07 as the fatty liver disease stage increased from normal to severe, indicating that the backscattered statistics vary from pre-Rayleigh to Rayleigh distributions. A significant positive correlation (correlation coefficient ρ = 0.84; probability value (p value) < 0.0001) exists between the degree of fatty infiltration and the Nakagami parameter, suggesting that ultrasound Nakagami imaging has potentials in future applications in fatty liver disease diagnosis. © IMechE 2015.

Tablet and Face-to-Face Hybrid Professional Development: Providing Earth Systems Science Educators Authentic Research Opportunities through The GLOBE Program at Purdue University

NASA Astrophysics Data System (ADS)

Wegner, K.; Branch, B. D.; Smith, S. C.

2013-12-01

The Global Learning and Observations to Benefit the Environment (GLOBE) program is a worldwide hands-on, primary and secondary school-based science and education program (www.globe.gov). GLOBE's vision promotes and supports students, teachers and scientists to collaborate on inquiry-based authentic science investigations of the environment and the Earth system working in close partnership with NASA, NOAA and NSF Earth System Science Projects (ESSP's) in study and research about the dynamics of Earth's environment. GLOBE Partners conduct face-to-face Professional Development in more than 110 countries, providing authentic scientific research experience in five investigation areas: atmosphere, earth as a system, hydrology, land cover, and soil. This presentation will provide a sample for a new framework of Professional Development that was implemented in July 2013 at Purdue University lead by Mr. Steven Smith who has tested GLOBE training materials for future training. The presentation will demonstrate how institutions can provide educators authentic scientific research opportunities through various components, including: - Carrying out authentic research investigations - Learning how to enter their authentic research data into the GLOBE database and visualize it on the GLOBE website - Learn how to access to NASA's Earth System Science resources via GLOBE's new online 'e-Training Program' - Exploring the connections of their soil protocol measurements and the history of the soil in their area through iPad soils app - LIDAR data exposure, Hydrology data exposure

Incomplete immunity to backscattering in chiral one-way photonic crystals.

PubMed

Cheng, Pi-Ju; Tien, Chung-Hao; Chang, Shu-Wei

2015-04-20

We show that the propagating modes in a strongly-guided chiral one-way photonic crystal are not backscattering-immune even though they are indeed insensitive to many kinds of scatters. Since these modes are not protected by the nonreciprocity, the backscattering does occur under certain circumstances. We use a perturbative method to derive criteria for the prominent backscattering in such chiral structures. From both our theory and numerical examinations, we find that the amount of backscattering critically depends on the symmetry of scatters. Additionally, for these chiral photonic modes, disturbances at the most intense parts of field profiles do not necessarily lead to the most effective backscattering.

Injuries of the globe: what can the radiologist offer?

PubMed

Sung, Edward K; Nadgir, Rohini N; Fujita, Akifumi; Siegel, Cory; Ghafouri, Roya H; Traband, Anastasia; Sakai, Osamu

2014-01-01

Traumatic ocular injuries are a significant cause of blindness and visual deficits. In the setting of acute orbital trauma, urgent ophthalmologic evaluation and intervention are critical in preserving vision. However, in the acute trauma setting, clinical evaluation of the globe may be difficult in the presence of surrounding periorbital soft-tissue swelling and other associated injuries, and patient cooperation may be limited because of unresponsiveness, altered mentation, or sedation. Often, rapid access to imaging is part of the initial diagnostic evaluation, and radiologists may be the first to identify traumatic injuries of the globe. Because of this, radiologists should be familiar with normal orbital and globe anatomy at various imaging modalities and have a thorough understanding of the various patterns of ocular injury and their imaging appearances. Radiologists should also be familiar with the various mimics of ocular injury, including congenital and acquired conditions that may alter the shape of the globe, various types of ocular calcifications, and the different types of material used to treat retinal detachment. Such knowledge may help radiologists make accurate diagnoses, which facilitates prompt and appropriate patient care. RSNA, 2014

The Citizen-Scientist as Data Collector: GLOBE at Night, Part 2

NASA Astrophysics Data System (ADS)

Walker, C. E.; Pompea, S. M.; Ward, D.; Henderson, S.; Meymaris, K.; Gallagher, S.; Salisbury, D.

2006-12-01

An innovative program to realize light pollution education on two continents via Internet 2-based videoconferencing was begun 4 years ago by the National Optical Astronomy Observatory. Bilingual science teachers and their students in Arizona and Chile recorded the brightness of the night sky by matching its appearance toward the constellation Orion with one of 6 stellar maps of limiting magnitude. Students from both hemispheres would report their findings via videoconferences. In the last year the program has evolved in collaboration with UCAR and other partners into an international, user-friendly, web-based science event open to anyone in the world, known as GLOBE at Night. GLOBE at Night uses the same design to observe and record the visible stars toward Orion, as a means of measuring light pollution in a given location. The inaugural event occurred over 11 nights last March, when 18,000 citizen- scientists made over 4,500 observations from 96 countries. Analysis of the GLOBE at Night data set found that the brighter skies corresponded to areas with higher population density, and that most observations were taken in a location with some light pollution. The data also tended to confirm that satellite data is reliable in assessing light pollution. This session will describe our program to incorporate more technology into the GLOBE at Night program. Citizen-scientists will use sky quality meters (visible light photometers), calibrated digital photography, and GPS as a means to measure and map more accurately the brightness of the sky at selected urban and rural sites. This extension of the program is designed to aid further in teaching about the impact of artificial lighting on local environments and the ongoing loss of a dark night sky as a natural resource. We will also describe how detailed maps of selected urban areas can be used to assess lighting design, safety considerations and energy usage. Given the widespread interest in the inaugural GLOBE at Night

Implementing GLOBE in the New York City Metropolitan Area: Trials, Errors, and Successes

NASA Astrophysics Data System (ADS)

Ludman, A.; Schmidt, P.; Borman, G.

2003-12-01

The Queens College GLOBE NY Metro Partnership was created to introduce GLOBE to more than 1.5 million students in southern NY State and provide continuing support for their teachers. In our first 18 months, we have trained 185 teachers from 82 schools and will triple these numbers this year. Teachers and administrators are attracted to GLOBE by its scientific rigor, the authentic research it offers students, and its fit with NYS standards. They are also eager to interact with our science faculty. Early difficulties included problems with the "standard" 5-day GLOBE training format and misconceptions that protocols are not suitable for urban settings and that preparing for the NYS Regents exams leaves no room for GLOBE. We held information meetings for school districts and for Queens high schools before our first workshop. These identified the most committed schools, energetic teachers, and potential implementation problems. Creative participants at these meetings countered the misconceptions and suggested solutions to the problems better than any outsider could, and generated an atmosphere leading to nearly 100% recruitment. The following stratagems have worked well: a close working relationship with the NYC Dept of Education, BOCES, and other environmental educators; affiliations with government agencies and community environmental groups; two bribes (giving a GLOBE instrument kit and GPS unit to each school that we train and awarding graduate or professional development credits for GLOBE training); a user-friendly training format (an initial 3-day workshop followed by two optional days for hydrology and land use); lending seldom-used items (e.g. soil auger) when needed; building a sense of GLOBE community with a graduation "ceremony", local website (www.qc.edu/qcglobe) and newsletter, phone and email helplines, and annual pedagogy and student research conferences. We also urge that three teachers be trained from each school in order to build local GLOBE support

Optical backscattering properties of the "clearest" natural waters

NASA Astrophysics Data System (ADS)

Twardowski, M. S.; Claustre, H.; Freeman, S. A.; Stramski, D.; Huot, Y.

2007-11-01

During the BIOSOPE field campaign October-December 2004, measurements of inherent optical properties from the surface to 500 m depth were made with a ship profiler at stations covering over 8000 km through the Southeast Pacific Ocean. Data from a ~3000 km section containing the very clearest waters in the central gyre are reported here. The total volume scattering function at 117°, βt(117°), was measured with a WET Labs ECO-BB3 sensor at 462, 532, and 650 nm with estimated uncertainties of 2×10-5, 5×10-6, and 2×10-6 m-1 sr-1, respectively. These values were approximately 6%, 3%, and 3% of the volume scattering by pure seawater at their respective wavelengths. From a methodological perspective, there were several results: - distributions were resolvable even though some of the values from the central gyre were an order of magnitude lower than the lowest previous measurements in the literature; - Direct in-situ measurements of instrument dark offsets were necessary to accurately resolve backscattering at these low levels; - accurate pure seawater backscattering values are critical in determining particulate backscattering coefficients in the open ocean (not only in these very clear waters); the pure water scattering values determined by Buiteveld et al. (1994) with a [1+0.3S/37] adjustment for salinity based on Morel (1974) appear to be the most accurate estimates, with aggregate accuracies as low as a few percent; and - closure was demonstrated with subsurface reflectance measurements reported by Morel et al. (2007) within instrument precisions, a useful factor in validating the backscattering measurements. This methodology enabled several observations with respect to the hydrography and the use of backscattering as a biogeochemical proxy: -The clearest waters sampled were found at depths between 300 and 350 m, from 23.5° S, 118° W to 26° S, 114° W, where total backscattering at 650 nm was not distinguishable from pure seawater; -Distributions of

Optical backscattering properties of the "clearest" natural waters

NASA Astrophysics Data System (ADS)

Twardowski, M. S.; Claustre, H.; Freeman, S. A.; Stramski, D.; Huot, Y.

2007-07-01

During the BIOSOPE field campaign October-December 2004, measurements of inherent optical properties from the surface to 500 m depth were made with a ship profiler at stations covering over ~8000 km through the Southeast Pacific Ocean. Data from a ~3000 km section containing the very clearest waters in the central gyre are reported here. The total volume scattering function at 117°, βt(117°), was measured with a WET Labs ECO-BB3 sensor at 462, 532, and 650 nm with estimated uncertainties of 2×10-5, 5×10-6, and 2×10-6 m-1 sr-1, respectively. These values were approximately 6%, 3%, and 3% of the scattering by pure seawater at their respective wavelengths. From a methodological perspective, there were several results: - bbp distributions were resolvable even though some of the values from the central gyre were an order of magnitude lower than the lowest previous measurements in the literature; - Direct in-situ measurements of instrument dark offsets were necessary to accurately resolve backscattering at these low levels; - accurate pure seawater backscattering values are critical in determining particulate backscattering coefficients in the open ocean (not only in these very clear waters); the pure water scattering values determined by Buiteveld et al. (1994) with a [1 + 0.3S/37] adjustment for salinity based on Morel (1974) appear to be the most accurate estimates, with aggregate accuracies as low as a few percent; and - closure was demonstrated with subsurface reflectance measurements reported by Morel et al. (2007) within instrument precisions, a useful factor in validating the backscattering measurements. This methodology enabled several observations with respect to the hydrography and the use of backscattering as a biogeochemical proxy: - The clearest waters sampled were found at depths between 300 and 350 m, from 23.5° S, 118° W to 26° S, 114° W, where total backscattering at 650 nm was not distinguishable from pure seawater; - Distributions of

A morphologically preserved multi-resolution TIN surface modeling and visualization method for virtual globes

NASA Astrophysics Data System (ADS)

Zheng, Xianwei; Xiong, Hanjiang; Gong, Jianya; Yue, Linwei

2017-07-01

Virtual globes play an important role in representing three-dimensional models of the Earth. To extend the functioning of a virtual globe beyond that of a "geobrowser", the accuracy of the geospatial data in the processing and representation should be of special concern for the scientific analysis and evaluation. In this study, we propose a method for the processing of large-scale terrain data for virtual globe visualization and analysis. The proposed method aims to construct a morphologically preserved multi-resolution triangulated irregular network (TIN) pyramid for virtual globes to accurately represent the landscape surface and simultaneously satisfy the demands of applications at different scales. By introducing cartographic principles, the TIN model in each layer is controlled with a data quality standard to formulize its level of detail generation. A point-additive algorithm is used to iteratively construct the multi-resolution TIN pyramid. The extracted landscape features are also incorporated to constrain the TIN structure, thus preserving the basic morphological shapes of the terrain surface at different levels. During the iterative construction process, the TIN in each layer is seamlessly partitioned based on a virtual node structure, and tiled with a global quadtree structure. Finally, an adaptive tessellation approach is adopted to eliminate terrain cracks in the real-time out-of-core spherical terrain rendering. The experiments undertaken in this study confirmed that the proposed method performs well in multi-resolution terrain representation, and produces high-quality underlying data that satisfy the demands of scientific analysis and evaluation.

A simple backscattering microscope for fast tracking of biological molecules

PubMed Central

Sowa, Yoshiyuki; Steel, Bradley C.; Berry, Richard M.

2010-01-01

Recent developments in techniques for observing single molecules under light microscopes have helped reveal the mechanisms by which molecular machines work. A wide range of markers can be used to detect molecules, from single fluorophores to micron sized markers, depending on the research interest. Here, we present a new and simple objective-type backscattering microscope to track gold nanoparticles with nanometer and microsecond resolution. The total noise of our system in a 55 kHz bandwidth is ∼0.6 nm per axis, sufficient to measure molecular movement. We found our backscattering microscopy to be useful not only for in vitro but also for in vivo experiments because of lower background scattering from cells than in conventional dark-field microscopy. We demonstrate the application of this technique to measuring the motion of a biological rotary molecular motor, the bacterial flagellar motor, in live Escherichia coli cells. PMID:21133475

Dark Skies Awareness through the GLOBE at Night Citizen-Science Campaign

NASA Astrophysics Data System (ADS)

Walker, C. E.

2011-10-01

The emphasis in the international citizen-science, star-hunting campaign, GLOBE at Night, is in bringing awareness to the public on issues of light pollution. Light pollution threatens not only observatory sites and our "right to starlight", but can affect energy consumption, wildlife and health. GLOBE at Night has successfully reached a few hundred thousand citizen-scientists during the annual 2-week campaign over the past 6 years. Provided is an overview, update and discussion of what steps can be taken to improve programs like GLOBE at Night.

Real-time, rapidly updating severe weather products for virtual globes

NASA Astrophysics Data System (ADS)

Smith, Travis M.; Lakshmanan, Valliappa

2011-01-01

It is critical that weather forecasters are able to put severe weather information from a variety of observational and modeling platforms into a geographic context so that warning information can be effectively conveyed to the public, emergency managers, and disaster response teams. The availability of standards for the specification and transport of virtual globe data products has made it possible to generate spatially precise, geo-referenced images and to distribute these centrally created products via a web server to a wide audience. In this paper, we describe the data and methods for enabling severe weather threat analysis information inside a KML framework. The method of creating severe weather diagnosis products that are generated and translating them to KML and image files is described. We illustrate some of the practical applications of these data when they are integrated into a virtual globe display. The availability of standards for interoperable virtual globe clients has not completely alleviated the need for custom solutions. We conclude by pointing out several of the limitations of the general-purpose virtual globe clients currently available.

Crowdsourced Science: Citizen Science Using the Globe Observer Mobile App

NASA Astrophysics Data System (ADS)

Low, R.; Riebeek Kohl, H.

2016-12-01

Field-based citizen science programs broaden public understanding of the Earth's system and connect users personally in seeing and understanding the changes that are taking place on our planet. GLOBE Observer (GO) is a new initiative for citizen scientists of all ages and connects users to NASA science via a simple smartphone app. Version 1.0 includes GLOBE Clouds, which guides users in photographing clouds and recording sky observations. Citizen scientist cloud observations are compared with NASA satellite images, and provide critical ground validation of satellite data so we better understand the Earth and its environment. The GLOBE Observer mobile app is equipped with data collection capabilities and visualization opportunities that lower the barrier for public participation in data collection and analysis efforts. Future releases of the GLOBE Observer app will support public engagement in investigations of the hydrosphere and biosphere. Some of the exciting developments on the horizon include in-app training games to build skills, in-app push messaging, which challenge a citizen scientist to participate data collection missions, and automated data validation capabilities.

The Role of Virtual Globes in Geoscience

NASA Technical Reports Server (NTRS)

Bailey, John E.; Chen, Aijun

2011-01-01

One of the difficulties faced by Earth scientists of all disciplines is how to effectively communicate their research to both other scientists and the general public. With increased attention paid to the health of the planet, the activities of geoscientists in particular are falling under the spotlight of public interest. In age where the internet availability has brought an expectation of information being instantly visible in a graphically rich format, the development of Virtual Globes --computer-based representations of the real-world--has become a natural progression for how best to view these data. In this special issue we bring together a cross-selection of the many examples of how Virtual Globe technologies are being used for geoscience.

Determining Light Pollution of the Global Sky: GLOBE at Night

NASA Astrophysics Data System (ADS)

Henderson, S.; Meymaris, K.; Ward, D.; Walker, C.; Russell, R.; Pompea, S.; Salisbury, D.

2006-05-01

GLOBE at Night is an international science event designed to observe and record the visible stars as a means of measuring light pollution in a given location. Increased and robust understanding of our environment requires learning opportunities that take place outside of the conventional K-12 classroom and beyond the confines of the school day. This hands-on learning activity extended the traditional classroom and school day last March with a week of nighttime sky observations involving teachers, students and their families. The quality of the night sky for stellar observations is impacted by several factors including human activities. By observing cloud cover and locating specific constellations in the sky, students from around the world learned how the lights in their community contribute to light pollution, exploring the relationship between science, technology and their society. Students learned that light pollution impacts more than just the visibility of stars at night. Lights at night impact both the biology and ecology of many species in our environment. Students were able to participate in this global scientific campaign by submitting their observations through an online database, allowing for authentic worldwide research and analysis by participating scientists. Students and their families learned how latitude and longitude coordinates provide a location system to map and analyze the observation data submitted from around the globe. The collected data is available online for use by students, teachers and scientists worldwide to assess how the quality of the night sky varies around the world. This session will share how students and scientists across the globe can explore and analyze the results of this exciting campaign. GLOBE at Night is a collaborative effort sponsored by The GLOBE Program, the National Optical Astronomy Observatory (NOAO), Centro de Apoyo a la Didactica de la Astronomia (CADIAS), Windows to the Universe, and ESRI. The GLOBE Program is

Criteria of backscattering in chiral one-way photonic crystals

NASA Astrophysics Data System (ADS)

Cheng, Pi-Ju; Chang, Shu-Wei

2016-03-01

Optical isolators are important devices in photonic circuits. To reduce the unwanted reflection in a robust manner, several setups have been realized using nonreciprocal schemes. In this study, we show that the propagating modes in a strongly-guided chiral photonic crystal (no breaking of the reciprocity) are not backscattering-immune even though they are indeed insensitive to many types of scatters. Without the protection from the nonreciprocity, the backscattering occurs under certain circumstances. We present a perturbative method to calculate the backscattering of chiral photonic crystals in the presence of chiral/achiral scatters. The model is, essentially, a simplified analogy to the first-order Born approximation. Under reasonable assumptions based on the behaviors of chiral photonic modes, we obtained the expression of reflection coefficients which provides criteria for the prominent backscattering in such chiral structures. Numerical examinations using the finite-element method were also performed and the results agree well with the theoretical prediction. From both our theory and numerical calculations, we find that the amount of backscattering critically depends on the symmetry of scatter cross sections. Strong reflection takes place when the azimuthal Fourier components of scatter cross sections have an order l of 2. Chiral scatters without these Fourier components would not efficiently reflect the chiral photonic modes. In addition, for these chiral propagating modes, disturbances at the most significant parts of field profiles do not necessarily result in the most effective backscattering. The observation also reveals what types of scatters or defects should be avoided in one-way applications of chiral structures in order to minimize the backscattering.

Clinical characteristics and outcomes of fall-related open globe injuries in Japan.

PubMed

Morikawa, Shohei; Okamoto, Yoshifumi; Okamoto, Fumiki; Inomoto, Naoki; Ishikawa, Hiroto; Harimoto, Kozo; Ueda, Tetsuo; Sakamoto, Taiji; Oshika, Tetsuro

2018-07-01

To investigate the clinical characteristics and visual outcomes in patients with fall-related open globe injuries and to evaluate differences between fall-related and non-fall-related open globe injuries in Japan. A retrospective review of patients with open globe injury who presented to Japan-Clinical Research of Study (J-CREST) hospitals between 2005 and 2015 was enrolled. Clinical information including age, sex, initial visual acuity, final visual acuity, type of injury, status of the crystalline lens, zone of injury, wound length, presence of retinal detachment, proliferative vitreoretinopathy, expulsive hemorrhage, and endophthalmitis was recorded. A total of 374 eyes were enrolled, of which 120 (32.1%) suffered from fall-related injury with average age of 73.7 ± 15.9 years (range, 11-101 years). A majority of patients were female (55.8%). Of 120 patients with fall-related injury, 109 (90.8%) presented with rupture and 11 (9.2%) with laceration. A multiple regression analysis revealed that final visual acuity was significantly associated with initial visual acuity (r = 0.99, P < 0.001). Compared to non-fall-related open globe injuries, fall-related open globe injuries were associated with elderly age, female sex, poorer initial and final visual acuity, rupture, absence of the lens, larger wound size, retinal detachment, expulsive hemorrhage, and absence of endophthalmitis (P < 0.01). Fall-related open globe injuries were more frequent in elderly female and accompanied by larger wound lengths and severer ocular complications. Visual outcomes in patients with fall-related open globe injuries were related to initial visual acuity.

The Citizen-Scientist as Data Collector: GLOBE at Night, Part 1

NASA Astrophysics Data System (ADS)

Ward, D. L.; Henderson, S.; Meymaris, K.; Walker, C.; Pompea, S. M.; Gallagher, S.; Salisbury, D.

2006-12-01

GLOBE at Night is an international science event designed to observe and record the visible stars as a means of measuring light pollution in a given location. Increased and robust understanding of our environment requires learning opportunities that take place outside of the conventional K-12 classroom and beyond the confines of the school day. This hands-on learning activity extended the traditional classroom and school day through 11 nights last March, when 18,000 citizen-scientists made over 4,500 observations from 96 countries. Utilizing the international networking capabilities of The GLOBE Program, GLOBE at Night was designed to make data collection and input user-friendly. Citizen-scientists were able to participate in this global scientific campaign by submitting their observations through an online database, allowing for authentic worldwide research and analysis by participating scientists. The data collected is available online in a variety of formats for use by students, teachers and scientists worldwide to assess how the quality of the night sky varies around the world. Using the online analysis tools provided by ESRI, participants were able to compare the observed data with population density and nighttime lighting datasets (DMSP Earth at Night). This comparison allowed correlations between observed data patterns and commonly used indices of population density and energy usage. This session will share our results and demonstrate how students and scientists across the globe can explore and analyze the results of this exciting campaign. We will discuss how the project team planned and executed the project in such a way that non-astronomers were able to make valid and useful contributions. We will also discuss lessons learned and best practices based on the 2006 campaign. GLOBE at Night is a collaborative effort sponsored by The GLOBE Program, the National Optical Astronomy Observatory (NOAO), Centro de Apoyo a la Didactica de la Astronomia (CADIAS

Coherent backscattering enhancement in cavities. Highlights of the role of symmetry.

PubMed

Gallot, Thomas; Catheline, Stefan; Roux, Philippe

2011-04-01

Through experiments and simulations, the consequences of symmetry on coherent backscattering enhancement (CBE) are studied in cavities. Three main results are highlighted. First, the CBE outside the source is observed: (a) on a single symmetric point in a one-dimensional (1-D) cavity, in a disk and in a symmetric chaotic plate; (b) on three symmetric points in a two-dimensional (2-D) rectangle; and (c) on seven symmetric points in a three-dimensional (3-D) parallelepiped cavity. Second, the existence of enhanced intensity lines and planes in 2-D and 3-D simple-shape cavities is demonstrated. Third, it is shown how the anti-symmetry caused by the special boundary conditions is responsible for the existence of a coherent backscattering decrement with a dimensional dependence of R = (½)(d), with d = 1,2,3 as the dimensionality of the cavity.

Improving predictive capabilities of environmental change with GLOBE data

NASA Astrophysics Data System (ADS)

Robin, Jessica Hill

This dissertation addresses two applications of Normalized Difference Vegetation Index (NDVI) essential for predicting environmental changes. The first study focuses on whether NDVI can improve model simulations of evapotranspiration for temperate Northern (>35°) regions. The second study focuses on whether NDVI can detect phenological changes in start of season (SOS) for high Northern (>60°) environments. The overall objectives of this research were to (1) develop a methodology for utilizing GLOBE data in NDVI research; and (2) provide a critical analysis of NDVI as a long-term monitoring tool for environmental change. GLOBE is an international partnership network of K-12 students, teachers, and scientists working together to study and understand the global environment. The first study utilized data collected by one GLOBE school in Greenville, Pennsylvania and the second utilized phenology observations made by GLOBE students in Alaska. Results from the first study showed NDVI could predict transpiration periods for environments like Greenville, Pennsylvania. In phenological terms, these environments have three distinct periods (QI, QII, and QIII). QI reflects onset of the growing season (mid March--mid May) when vegetation is greening up (NDVI < 0.60) and transpiration is less than 2mm/day. QII reflects end of the growing season (mid September--October) when vegetation is greening down and transpiration is decreasing. QIII reflects height of the growing season (mid May--mid September) when transpiration rates average between 2 and 5 mm per day and NDVI is at its maximum (>0.60). Results from the second study showed that a climate threshold of 153 +/- 22 growing degree days was a better predictor of SOS for Fairbanks than a NDVI threshold applied to temporal AVHRR and MODIS datasets. Accumulated growing degree days captured the interannual variability of SOS better than the NDVI threshold and most closely resembled actual SOS observations made by GLOBE students

Visual outcomes and prognostic factors in open-globe injuries.

PubMed

Fujikawa, Azusa; Mohamed, Yasser Helmy; Kinoshita, Hirofumi; Matsumoto, Makiko; Uematsu, Masafumi; Tsuiki, Eiko; Suzuma, Kiyoshi; Kitaoka, Takashi

2018-06-08

Ocular trauma is an important cause of visual loss worldwide. Improvements in our knowledge of the pathophysiology and management of ocular trauma during the past 30 years, in conjunction with advances in the instrumentation and techniques of ocular surgery, have improved the efficacy of vitreoretinal surgery in injured eyes. The aim of the current study was to determine the visual outcomes and prognostic factors of open-globe injuries in the Japanese population. Retrospective study of 59 eyes of 59 patients presented with open globe injuries between September 2008 and March 2014 at Nagasaki University Hospital was conducted. Demographic factors including age, gender, and clinical data such as cause of injury, presenting visual acuity (VA), location of injury, type of injury, lens status, presence of intraocular foreign body, types of required surgeries, and final VA were recorded. According to the classification of Ocular Trauma Classification Group, wound location was classified into three zones. Chi-square test was used to compare presented data. Out of the 59 patients, 46 were placed in the Light Perception (LP) group, and 13 were placed in the No Light Perception (NLP) group. Work-related trauma was the most common cause (27 eyes) followed by falls (19eyes). Work-related trauma was common in males (P = 0.004), while falls was significantly common in females (P = 0.00001). Zone III injuries had statistically significantly poor prognostic factor compared to other zones (P = 0.04). All cases of NLP group (100%) presented with rupture globe. Poor VA at first visit (P = 0.00001), rupture globe (P = 0.026), history of penetrating keratoplasty (PK) (P = 0.017), retinal detachment (RD) (P = 0.0001), vitreous hemorrhage (VH) (P = 0.044), and dislocation of crystalline lens (P = 0.0003) were considered as poor prognostic factors. Poor VA at first visit, rupture globe, zone III injuries, history of penetrating keratoplasty, RD, VH, and

Raman backscatter measurement research on water vapor systems

NASA Technical Reports Server (NTRS)

Workman, G. L.

1975-01-01

Raman backscatter techniques proved to be a useful remote sensing tool, whose full potential has not been realized. The types of information available from laser probes in atmospheric studies are reviewed. Detection levels for known Raman cross sections are calculated using the laser radar equation. Laboratory experiments performed for H2O, N2, SO2, O2 and HCL indicate that accurate wavelength cross sections need to be obtained, as well as more emphasis on obtaining accurate Raman cross sections of molecular species at wavelengths in the ultraviolet spectra.

A Review of Global Learning & Observations to Benefit the Environment (GLOBE)

DTIC Science & Technology

2010-04-01

review (Yoder et al., 2008) of the GPO performance, NASA continued the cooperative agreement with UCAR. Another external review ( Bybee et al., 2008) of...Submitted by the Program Office External Review Committee. Bybee , Rodger W. (Chair), 2008. NASA External Review of a GLOBE Proposal, The Globe

The GLOBE Program in Alabama: A Mentoring Approach to State-wide Implementation

NASA Astrophysics Data System (ADS)

Cox, G. N.

2003-12-01

Established in 1997, the GLOBE in Alabama (GIA) partnership has trained more than 1,000 teachers in almost 500 schools - over 25% of the total number of K-12 schools in Alabama. Over those five years, GIA has strived to achieve recognition of GLOBE as the "glue" to Alabama's new education program, the Alabama Math, Science and Technology Initiative (AMSTI). In 2003, GIA trained over 370 AMSTI K-8 teachers at two AMSTI hub sites in north Alabama. As the AMSTI program grows with the addition of future hub sites (eleven are planned), GIA must ready itself to train thousands of AMSTI teachers during the two-week summer professional development institutes that are part of AMSTI. A key component of AMSTI is a mentoring program conducted by math and science specialists - classroom educators loaned to the AMSTI hub sites by the school systems each hub site serves. The AMSTI mentoring program mirrors the GIA mentoring model begun in 1999 that originally funded regional GLOBE master teachers to provide technical assistance, feedback, and coaching for other GLOBE teachers. In schools where GIA mentor teachers were working, nearly a 100% increase in GLOBE student data reporting was noted. The GIA mentors now work within the hub site framework to ensure implementation of GLOBE as an integrated part of AMSTI. With the continued support of the State of Alabama, GIA will establish a network of mentors who work with the AMSTI hub site specialists in providing support for all AMSTI teachers. GIA is administered by the National Space Science and Technology Center, a partnership between NASA and the State of Alabama's seven research universities. Operational funding for GIA has been provided by the University of Alabama in Huntsville's Earth System Science Center, the NASA Marshall Space Flight Center, the Alabama Space Grant Consortium, The Alabama Department of Economic and Community Affairs, the Alabama State Department of Education, and Legacy. GIA has been able to build on these

Lidar inversion of atmospheric backscatter and extinction-to-backscatter ratios by use of a Kalman filter.

PubMed

Rocadenbosch, F; Soriano, C; Comerón, A; Baldasano, J M

1999-05-20

A first inversion of the backscatter profile and extinction-to-backscatter ratio from pulsed elastic-backscatter lidar returns is treated by means of an extended Kalman filter (EKF). The EKF approach enables one to overcome the intrinsic limitations of standard straightforward nonmemory procedures such as the slope method, exponential curve fitting, and the backward inversion algorithm. Whereas those procedures are inherently not adaptable because independent inversions are performed for each return signal and neither the statistics of the signals nor a priori uncertainties (e.g., boundary calibrations) are taken into account, in the case of the Kalman filter the filter updates itself because it is weighted by the imbalance between the a priori estimates of the optical parameters (i.e., past inversions) and the new estimates based on a minimum-variance criterion, as long as there are different lidar returns. Calibration errors and initialization uncertainties can be assimilated also. The study begins with the formulation of the inversion problem and an appropriate atmospheric stochastic model. Based on extensive simulation and realistic conditions, it is shown that the EKF approach enables one to retrieve the optical parameters as time-range-dependent functions and hence to track the atmospheric evolution; the performance of this approach is limited only by the quality and availability of the a priori information and the accuracy of the atmospheric model used. The study ends with an encouraging practical inversion of a live scene measured at the Nd:YAG elastic-backscatter lidar station at our premises at the Polytechnic University of Catalonia, Barcelona.

Nimbus 7 solar backscatter ultraviolet (SBUV) ozone products user's guide

NASA Technical Reports Server (NTRS)

Fleig, Albert J.; Mcpeters, R. D.; Bhartia, P. K.; Schlesinger, Barry M.; Cebula, Richard P.; Klenk, K. F.; Taylor, Steven L.; Heath, Donald F.

1990-01-01

Three ozone tape products from the Solar Backscatter Ultraviolet (SBUV) experiment aboard Nimbus 7 were archived at the National Space Science Data Center. The experiment measures the fraction of incoming radiation backscattered by the Earth's atmosphere at 12 wavelengths. In-flight measurements were used to monitor changes in the instrument sensitivity. Total column ozone is derived by comparing the measurements with calculations of what would be measured for different total ozone amounts. The altitude distribution is retrieved using an optimum statistical technique for the inversion. The estimated initial error in the absolute scale for total ozone is 2 percent, with a 3 percent drift over 8 years. The profile error depends on latitude and height, smallest at 3 to 10 mbar; the drift increases with increasing altitude. Three tape products are described. The High Density SBUV (HDSBUV) tape contains the final derived products - the total ozone and the vertical ozone profile - as well as much detailed diagnostic information generated during the retrieval process. The Compressed Ozone (CPOZ) tape contains only that subset of HDSBUV information, including total ozone and ozone profiles, considered most useful for scientific studies. The Zonal Means Tape (ZMT) contains daily, weekly, monthly and quarterly averages of the derived quantities over 10 deg latitude zones.

Enhanced backscatter of optical beams reflected in turbulent air

NASA Astrophysics Data System (ADS)

Nelson, W.; Palastro, J. P.; Wu, C.; Davis, C. C.

2015-07-01

Optical beams propagating through air acquire phase distortions from turbulent fluctuations in the refractive index. While these distortions are usually deleterious to propagation, beams reflected in a turbulent medium can undergo a local recovery of spatial coherence and intensity enhancement referred to as enhanced backscatter (EBS). Using a combination of lab-scale experiments and simulations, we investigate the EBS of optical beams reflected from corner cubes and rough surfaces, and identify the regimes in which EBS is most distinctly observed.

A Backscattering Enhanced Microwave Canopy Scattering Model Based On MIMICS

NASA Astrophysics Data System (ADS)

Shen, X.; Hong, Y.; Qin, Q.; Chen, S.; Grout, T.

2010-12-01

For modeling microwave scattering of vegetated areas, several microwave canopy scattering models, based on the vectorized radiative transfer equation (VRT) that use different solving techniques, have been proposed in the past three decades. As an iterative solution of VRT at low orders, the Michigan Microwave Canopy Scattering Model (MIMICS) gives an analytical expression for calculating scattering as long as the volume scattering is not too strong. The most important usage of such models is to predict scattering in the backscattering direction. Unfortunately, the simplified assumption of MIMICS is that the scattering between the ground and trunk layers only includes the specular reflection. As a result, MIMICS includes a dominant coherent term which vanishes in the backscattering direction because this term contains a delta function factor of zero in this direction. This assumption needs reconsideration for accurately calculating the backscattering. In the framework of MIMICS, any incoherent terms that involve surface scattering factors must at least undergo surface scattering twice and volume scattering once. Therefore, these incoherent terms are usually very weak. On the other hand, due to the phenomenon of backscattering enhancement, the surface scattering in the backscattering direction is very strong compared to most other directions. Considering the facts discussed above, it is reasonable to add a surface backscattering term to the last equation of the boundary conditions of MIMICS. More terms appear in the final result including a backscattering coherent term which enhances the backscattering. The modified model is compared with the original MIMICS (version 1.0) using JPL/AIRSAR data from NASA Campaign Soil Moisture Experimental 2003 (SMEX03) and Washita92. Significant improvement is observed.

Ocean subsurface particulate backscatter estimation from CALIPSO spaceborne lidar measurements

NASA Astrophysics Data System (ADS)

Chen, Peng; Pan, Delu; Wang, Tianyu; Mao, Zhihua

2017-10-01

A method for ocean subsurface particulate backscatter estimation from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite was demonstrated. The effects of the CALIOP receiver's transient response on the attenuated backscatter profile were first removed. The two-way transmittance of the overlying atmosphere was then estimated as the ratio of the measured ocean surface attenuated backscatter to the theoretical value computed from wind driven wave slope variance. Finally, particulate backscatter was estimated from the depolarization ratio as the ratio of the column-integrated cross-polarized and co-polarized channels. Statistical results show that the derived particulate backscatter by the method based on CALIOP data agree reasonably well with chlorophyll-a concentration using MODIS data. It indicates a potential use of space-borne lidar to estimate global primary productivity and particulate carbon stock.

Backscatter absorption gas imaging system

DOEpatents

McRae, Jr., Thomas G.

1985-01-01

A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

Backscatter absorption gas imaging system

DOEpatents

McRae, T.G. Jr.

A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

GLOBE and the Earth SySTEM Model in Teacher Preparation

NASA Astrophysics Data System (ADS)

Jabot, M.; Moore, J.; Dorofy, P.

2017-12-01

This presentation will share the growing body of work linking ArcMap and GLOBE and the Earth SySTEM approach in the development of preservice teachers. Our work is linking the power of ArcMap with the vast database of GLOBE in a unique way that links the power of geospatial technologies in shaping the planning for and delivery of science instruction in the P-5 classroom.

Computer simulation of backscattering spectra from paint

NASA Astrophysics Data System (ADS)

Mayer, M.; Silva, T. F.

2017-09-01

To study the role of lateral non-homogeneity on backscattering analysis of paintings, a simplified model of paint consisting of randomly distributed spherical pigment particles embedded in oil/binder has been developed. Backscattering spectra for lead white pigment particles in linseed oil have been calculated for 3 MeV H+ at a scattering angle of 165° for pigment volume concentrations ranging from 30 vol.% to 70 vol.% using the program STRUCTNRA. For identical pigment volume concentrations the heights and shapes of the backscattering spectra depend on the diameter of the pigment particles: This is a structural ambiguity for identical mean atomic concentrations but different lateral arrangement of materials. Only for very small pigment particles the resulting spectra are close to spectra calculated supposing atomic mixing and assuming identical concentrations of all elements. Generally, a good fit can be achieved when evaluating spectra from structured materials assuming atomic mixing of all elements and laterally homogeneous depth distributions. However, the derived depth profiles are inaccurate by a factor of up to 3. The depth range affected by this structural ambiguity ranges from the surface to a depth of roughly 0.5-1 pigment particle diameters. Accurate quantitative evaluation of backscattering spectra from paintings therefore requires taking the correct microstructure of the paint layer into account.

Identification of major backscattering sources in trees and shrubs at 10 GHz

NASA Technical Reports Server (NTRS)

Zoughi, R.; Wu, L. K.; Moore, R. K.

1986-01-01

A short-range very-fine-resolution FM-CW radar scatterometer has been used to identify the primary contributors to 10-GHz radar backscatter from pine, pin oak, American sycamore and sugar maple trees, and from creeping juniper shrubs. This system provided a range resolution of 11 cm and gave a 16-cm diameter illumination area at the target range of about 4 m. For a pine tree, the needles caused the strongest backscatter as well as the strongest attenuation in the radar signal. Cones, although insignificant contributors to the total backscatter, were more important for backscattering than for attenuation. For the rest of the trees, leaves were the strongest cause of backscattering and attenuation. However, in the absence of leaves, the petioles, small twigs, and branches gave relatively strong backscatter. For American sycamore and sugar maple trees, the fruits did not affect the total backscatter unless they were packed in clusters. For creeping juniper the backscattered energy and attenuation in the radar signal were mainly due to the top two layers of the evergreen scales. The contribution of the tree trunks was not determined.

The GLOBE at Night Campaign: Promoting Dark Skies Awareness Beyond IYA2009

NASA Astrophysics Data System (ADS)

Walker, Constance E.

2010-01-01

One of the most productive programs in the IYA2009 Dark Skies Awareness Cornerstone Project has been GLOBE at Night. The GLOBE at Night program has endeavored to promote social awareness of the dark sky by getting the general public to measure light pollution and submit results on-line. During IYA2009 alone, over 15,700 measurements from 70 countries were contributed during the 2-week campaign period. That amount is twice the number of measurements on average from previous years. The GLOBE at Night website explains clearly the simple-to-participate-in 5 step program and offers background information and interactive games on key concepts. The program has been expanded to include trainings of the general public, but especially educators in schools, museums and science centers, in unique ways. Education kits for Dark Skies Awareness have been distributed at these training workshops. The kit includes material for a light shielding demonstration, a digital Sky Quality Meter and Dark Skies Ranger Activities. The activities are on how unshielded light wastes energy, how light pollution affects wildlife and how you can participate in a citizen-science star-hunt like GLOBE at Night. In addition, projects are being developed for what to do with the data once it is taken. There were particularly spirited and creative GLOBE at Night campaigns around the world in 2009. One such "poster child” was carried out by 6500 students in northern Indiana. The students produced 3,391 GLOBE at Night measurements. To visualize the magnitudes of dark sky lost to light pollution, these students removed over 12,000 of the 35,000 stacked LEGO blocks that represented an ideal night sky across the school district. The presentation will provide an update with lessons learned, describe how people can become involved and take a look ahead at the program's sustainability. For further information, visit www.globe.gov/globeatnight.

Bruce Thompson: Adventures and advances in ultrasonic backscatter

NASA Astrophysics Data System (ADS)

Margetan, Frank J.

2012-05-01

Over the course of his professional career Dr. R. Bruce Thompson published several hundred articles on non-destructive evaluation, the majority dealing with topics in ultrasonics. One longtime research interest of Dr. Thompson, with applications both to microstructure characterization and defect detection, was backscattered grain noise in metals. Over a 20 year period he led a revolving team of staff members and graduate students investigating various aspects of ultrasonic backscatter. As a member of that team I had the privilege of working along side Dr. Thompson for many years, serving as a sort of Dr. Watson to Bruce's Sherlock Holmes. This article discusses Dr. Thompson's general approaches to modeling backscatter, the research topics he chose to explore to systematically elucidate a better understanding of the phenomena, and the many contributions to the field achieved under his leadership. The backscatter work began in earnest around 1990, motivated by a need to improve inspections of aircraft engine components. At that time Dr. Thompson launched two research efforts. The first led to the heuristic Independent Scatterer Model which could be used to estimate the average grain noise level that would be seen in any given ultrasonic inspection. There the contribution from the microstructure was contained in a measureable parameter known as the Figure-of-Merit or FOM. The second research effort, spearheaded by Dr. Jim Rose, led to a formal relationship between FOM and details of the metal microstructure. The combination of the Independent Scattering Model and Rose's formalism provided a powerful tool for investigating backscatter in metals. In this article model developments are briefly reviewed and several illustrative applications are discussed. These include: the determination of grain size and shape from ultrasonic backscatter; grain noise variability in engine-titanium billets and forgings; and the design of ultrasonic inspection systems to improve defect

High-frequency attenuation and backscatter measurements of rat blood between 30 and 60 MHz.

PubMed

Huang, Chih-Chung

2010-10-07

There has recently been a great deal of interest in noninvasive high-frequency ultrasound imaging of small animals such as rats due to their being the preferred animal model for gene therapy and cancer research. Improving the interpretation of the obtained images and furthering the development of the imaging devices require a detailed knowledge of the ultrasound attenuation and backscattering of biological tissue (e.g. blood) at high frequencies. In the present study, the attenuation and backscattering coefficients of the rat red blood cell (RBC) suspensions and whole blood with hematocrits ranging from 6% to 40% were measured between 30 and 60 MHz using a modified substitution approach. The acoustic parameters of porcine blood under the same conditions were also measured in order to compare differences in the blood properties between these two animals. For porcine blood, both whole blood and RBC suspension were stirred at a rotation speed of 200 rpm. Three different rotation speeds of 100, 200 and 300 rpm were carried out for rat blood experiments. The attenuation coefficients of both rat and porcine blood were found to increase linearly with frequency and hematocrit (the values of coefficients of determination (r(2)) are around 0.82-0.97 for all cases). The average attenuation coefficient of rat whole blood with a hematocrit of 40% increased from 0.26 Nepers mm(-1) at 30 MHz to 0.47 Nepers mm(-1) at 60 MHz. The maximum backscattering coefficients of both rat and porcine RBC suspensions were between 10% and 15% hematocrits at all frequencies. The fourth-power dependence of backscatter on frequency was approximately valid for rat RBC suspensions with hematocrits between 6% and 40%. However, the frequency dependence of the backscatter estimate deviates from a fourth-power law for porcine RBC suspension with hematocrit higher than 20%. The backscattering coefficient plateaued for hematocrits higher than 15% in porcine blood, but for rat blood it was maximal around a

Observation of coherent backscattering of light in ultracold ^85Rb

NASA Astrophysics Data System (ADS)

Kulatunga, P.; Sukenik, C. I.; Havey, M. D.; Kupriyanov, D. V.; Sokolov, I. M.

2002-05-01

We report investigation of multiple coherent light scattering from ^85Rb atoms confined in a magneto-optic trap. In experimental studies, measurements are made of coherent backscattering of a low-intensity probe beam tuned near the F = 3 - F' = 4 transition in ^85Rb atoms. Polarization of backscattered light is determined by a backscattering polarimeter; the spatial distribution of light intensity is measured by a liquid-nitrogen cooled CCD camera set in the focal plane of the analyzing optics. The instrument has angular resolution of about 100 micro-radians, and a polarization analyzing power of roughly 1000. In this paper we describe the instrument details, including calibration procedures, and our measurements of atomic coherent backscattering. In a theoretical study of intensity enhancement of near-resonant backscattered light from cold ^85,87Rb atoms, we consider scattering orders up to 8 and a Gaussian atom distribution in the MOT. Enhancement factors are calculated for all D1 and D2 hyperfine components and for both isotopes.

Whole-globe biomechanics using high-field MRI.

PubMed

Voorhees, Andrew P; Ho, Leon C; Jan, Ning-Jiun; Tran, Huong; van der Merwe, Yolandi; Chan, Kevin; Sigal, Ian A

2017-07-01

The eye is a complex structure composed of several interconnected tissues acting together, across the whole globe, to resist deformation due to intraocular pressure (IOP). However, most work in the ocular biomechanics field only examines the response to IOP over smaller regions of the eye. We used high-field MRI to measure IOP induced ocular displacements and deformations over the whole globe. Seven sheep eyes were obtained from a local abattoir and imaged within 48 h using MRI at multiple levels of IOP. IOP was controlled with a gravity perfusion system and a cannula inserted into the anterior chamber. T2-weighted imaging was performed to the eyes serially at 0 mmHg, 10 mmHg, 20 mmHg and 40 mmHg of IOP using a 9.4 T MRI scanner. Manual morphometry was conducted using 3D visualization software to quantify IOP-induced effects at the globe scale (e.g. axial length and equatorial diameters) or optic nerve head scale (e.g. canal diameter, peripapillary sclera bowing). Measurement sensitivity analysis was conducted to determine measurement precision. High-field MRI revealed an outward bowing of the posterior sclera and anterior bulging of the cornea due to IOP elevation. Increments in IOP from 10 to 40 mmHg caused measurable increases in axial length in 6 of 7 eyes of 7.9 ± 5.7% (mean ± SD). Changes in equatorial diameter were minimal, 0.4 ± 1.2% between 10 and 40 mmHg, and in all cases less than the measurement sensitivity. The effects were nonlinear, with larger deformations at normal IOPs (10-20 mmHg) than at elevated IOPs (20-40 mmHg). IOP also caused measurable increases in the nasal-temporal scleral canal diameter of 13.4 ± 9.7% between 0 and 20 mmHg, but not in the superior-inferior diameter. This study demonstrates that high-field MRI can be used to visualize and measure simultaneously the effects of IOP over the whole globe, including the effects on axial length and equatorial diameter, posterior sclera displacement and bowing, and even

Effects of soil and canopy characteristics on microwave backscattering of vegetation

NASA Technical Reports Server (NTRS)

Daughtry, C. S. T.; Ranson, K. J.

1991-01-01

A frequency modulated continuous wave C-band (4.8 GHz) scatterometer was mounted on an aerial lift truck and backscatter coefficients of corn were acquired as functions of polarizations, view angles, and row directions. As phytomass and green leaf area index increased, the backscatter also increased. Near anthesis when the canopies were fully developed, the major scattering elements were located in the upper 1 m of the 2.8 m tall canopy and little backscatter was measured below that level. C-band backscatter data could provide information to monitor vegetation at large view zenith angles.

Engaging the Public in the Citizen Science GLOBE at Night Campaign

NASA Astrophysics Data System (ADS)

Walker, Constance E.; Sparks, R. T.; Pompea, S. M.

2011-05-01

The emphasis in the international star-hunting campaign, GLOBE at Night, is in bringing awareness to the public on issues of light pollution. Light pollution threatens not only observatory sites and our "right to starlight", but can affect energy consumption, wildlife and health. GLOBE at Night has successfully reached a few 100,000 citizen-scientists. What steps can be taken to improve it? To promote the campaign via popular social media, GLOBE at Night created Facebook and Twitter pages. To increase participation in the 2011 campaign, children and adults submitted their sky brightness measurements in real time with smart phones or tablets using the web application at www.globeatnight.org/webapp/. With smart phones and tablets, the location, date and time register automatically. For those without smart mobile devices, user-friendly tools on the GLOBE at Night report page were reconfigured to determine latitude and longitude more easily and accurately. To increase the robustness of the data, 2 new approaches were taken. GLOBE at Night prototyped an "Adopt a Street” program in Tucson. The aim was for people to adopt different major or semi-major streets and take measurements every mile or so for the length of the street. The grid of measurements would canvas the town, allowing for comparisons of light levels over time (hours, days, years) or search for dark sky oases or light polluted areas. The increase to 2 campaigns in 2011 re-enforces these studies. The intent is to offer the program year-round for seasonal studies. The data can also be used to compare with datasets on wildlife, health, and energy consumption. Recently, NOAO and the Arizona Game and Fish Department have started a project with GLOBE at Night data and bat telemetry to examine a dark skies corridor in Tucson where the endangered bats fly. In our presentation, results of our efforts are discussed.

Measure of Backscatter for small particles of atmosphere by lasers

NASA Astrophysics Data System (ADS)

Abud, Mariam M.

2018-05-01

It developed a program for the atmosphere to study the backscattering for contents gas and molecules, aerosol, fog, clouds and rain droplets. By using Rayleigh, Mie and geometric scattering. The aim of research, using different types of lasers from various optical region, is to calculate differential cross scatter section and backscatter of atmosphere component in one layer from height 10-2000m. 180° is backscattering angle using ISA standard sea level condition P=1013.25 (kpa) at t0=15 ° C.and then calculated the density of molecules and water vapor molecules represented D in kg/m3. Results reflected index consist of the large value of the real part and imaginary m=1.463-0.028i.this research diff. scatter cross section of different component of atmosphere layer decreased vs. wavelengths. The purpose of lider research to find backscatter from UV to IR laser within the optical range in the atmosphere and measurement of excitation and analysis of backscatter signals. Recently, the atmosphere of Iraq has become full of dust and pollution, so by knowing the differential cross scatter section and backscatter of atmosphere. Relation between total Rayleigh scatter coefficient & type of particles include fog and clouds, aerosols and water droplets (-0.01, 0.025,- 0.005) m-1/sr-1.

Engaging Communities to Understand and Adapt to Environmental Changes with The GLOBE Program

NASA Astrophysics Data System (ADS)

Wegner, K.; Malmberg, J. S.; Murphy, T.; Mauriello, H.

2015-12-01

During the past twenty years, The GLOBE Program (www.globe.gov) has connected scientists, K-12 students, teachers, and other stakeholders to "co-create" scientific understanding of their local, regional, and global environment in more than 110 countries. Through the support and collaboration of federal agencies- NASA, NSF, and NOAA- the community-driven GLOBE database has more than 130 million Earth science measurements (atmosphere, biosphere, hydrosphere, and pedosphere) that align with the USGCRP's indicators of climate change, such as air and surface temperature (Indicator: Global Surface Temperature), land cover (Indicators: 1) Forest Cover; 2) Grassland, Shrubland, and Pasture Cover), and plant phenology (Indicator: Start of Spring). GLOBE contributes to climate literacy while encouraging community members of all ages to enrich their scientific understanding, define issues of local relevance, and engage in broader action, such as regional and global science campaigns. In this session, we will present case studies of how GLOBE data has been used to inspire "homegrown" research campaigns such as the GLOBE Surface Temperature Campaign and European Aerosols Campaign, as well as solution-based action in response to environmental changes, including the development of a mosquito protocol in Thailand and across Africa and a toad service project in the Czech Republic. We will also discuss some of the initiatives we have led as a program in order to promote and share local and regional community-led efforts with our worldwide GLOBE community, as well as some of the challenges and opportunities presented by supporting climate research.

Effect of mannitol on globe and orbital volumes in humans.

PubMed

Weber, Adam C; Blandford, Alexander D; Costin, Bryan R; Perry, Julian D

2018-03-01

To determine the effect of intravenous mannitol on globe and orbital volumes. Retrospective chart review of a consecutive series of Cleveland Clinic Neurosurgical Intensive Care Unit patients who underwent computed tomographic imaging before and after intravenous mannitol administration. Volume measurements were performed according to a previously described technique by averaging axial image areas. Measurements before and after mannitol administration were compared using paired t-test. Fourteen patients (28 eyes) met inclusion criteria. Average globe volume decreased 186 mm 3 (-2.5%, p = 0.02) after mannitol administration, while average orbital volume increased 353 mm 3 (+3.5%, p = 0.04). Average globe volume change for subjects with follow-up scan less than 4.7 hours (mean 1.9 hours; range 0.2-4.5 hours) after mannitol administration was -125 mm 3 (-1.7%, p = 0.24) and average orbital volume change was +458 mm 3 (+5.1%, p = 0.11). Average globe volume change after mannitol administration for those with follow-up more than 4.7 hours (average 13.9 hours, range 4.9-24.7 hours) was -246 mm 3 (-3.3%, p = 0.05) and orbital volume change was +248 mm 3 (+2.2%, p = 0.24). Dividing the study population into groups based on mannitol dose did not yield any statistically significant change. Human globe volume decreases after intravenous mannitol administration, while orbital volume increases. These volume changes occur during the time period when intraocular pressure normalizes, after the pressure-lowering effects of the drug. This novel volumetric information improves our understanding of mannitol's mechanism of action and its effects on human ocular and periocular tissues.

How Cool was the Eclipse? Atmospheric Measurements and Citizen Science via NASA's GLOBE Observer

NASA Astrophysics Data System (ADS)

Weaver, K. L. K.; Riebeek Kohl, H.

2017-12-01

The solar eclipse of 2017 presented an extraordinary opportunity to engage the public in shared science activity across the entire United States. While a natural focus of the eclipse was on astronomy and heliophysics, there was also an opening for excellent connections to Earth science. Because of the excitement of the event, many people gathered for long periods before and after totality, a perfect opportunity for observations and data collection to explore the impact of the eclipse on the atmosphere. The data was collected via NASA's GLOBE Observer app, a subset of the Global Learning and Observations to Benefit the Environment Program, a citizen science project which has been active for more than 20 years training teachers to collect many different types of environmental science data with their students. GLOBE Observer expands that audience to citizen scientists who might not be connected to a school, but are still interested in collecting data. In addition to the clouds observations that are normally part of GLOBE Observer, a special temporary protocol was added for the eclipse to include air temperature. Both types of measurements were collected at regular intervals for several hours before and after the point of maximum eclipse. By crowdsourcing data from all across the United States, on and off the path of totality, the hope was to be able to see patterns that wouldn't be apparent with fewer data points. In particular, there are few sources of detailed cloud data from the ground, including cloud type as well as overall cloud cover, especially as collected during a unique natural experiment such as an eclipse. This presentation will report preliminary results of the GLOBE Observer eclipse citizen science project, including participation totals and impact, data site distribution, as well as early analyses of both temperature and cloud data.

GLOBE: A Science/Education Partnership Program.

ERIC Educational Resources Information Center

Murphy, Anthony P.; Coppola, Ralph K.

This paper reviews the history of the GLOBE (Global Learning and Observations to Benefit the Environment) Program, an international environmental science education program. The goals of the program are to: enhance the environmental awareness of individuals around the world; contribute to the scientific understanding of the earth; and to help all…

Analysis of C and Ku band ocean backscatter measurements under low-wind conditions

NASA Astrophysics Data System (ADS)

Carswell, James R.; Donnelly, William J.; McIntosh, Robert E.; Donelan, Mark A.; Vandemark, Douglas C.

1999-09-01

Airborne ocean backscatter measurements at C and Ku band wavelengths obtained in low to moderate-wind conditions are presented. The differences between the low-wind backscatter data and the CMOD4 and SASS-II models are reported. The measurements show that the upwind/crosswind backscatter ratio is greater than predicted. These large upwind/crosswind backscatter ratios are attributed to a rapid decrease in the crosswind backscatter at low winds. Qualitative agreement with the composite surface model proposed by Donelan and Pierson suggests the rapid decrease in the crosswind backscatter may be caused by viscous dampening of the Bragg-resonant capillary-gravity waves. We show that for larger antenna footprints typical of satellite-based scatterometers, the variability in the observed wind field smooths out the backscatter response such that the rapid decrease in the crosswind direction is not observed.

Quantitative Ultrasound Backscatter for Pulsed Cavitational Ultrasound Therapy—Histotripsy

PubMed Central

Wang, Tzu-Yin; Xu, Zhen; Winterroth, Frank; Hall, Timothy L.; Fowlkes, J. Brian; Rothman, Edward D.; Roberts, William W.; Cain, Charles A.

2011-01-01

Histotripsy is a well-controlled ultrasonic tissue ablation technology that mechanically and progressively fractionates tissue structures using cavitation. The fractionated tissue volume can be monitored with ultrasound imaging because a significant ultrasound backscatter reduction occurs. This paper correlates the ultrasound backscatter reduction with the degree of tissue fractionation characterized by the percentage of remaining normal-appearing cell nuclei on histology. Different degrees of tissue fractionation were generated in vitro in freshly excised porcine kidneys by varying the number of therapeutic ultrasound pulses from 100 to 2000 pulses per treatment location. All ultrasound pulses were 15 cycles at 1 MHz delivered at 100 Hz pulse repetition frequency and 19 MPa peak negative pressure. The results showed that the normalized backscatter intensity decreased exponentially with increasing number of pulses. Correspondingly, the percentage of normal appearing nuclei in the treated area decreased exponentially as well. A linear correlation existed between the normalized backscatter intensity and the percentage of normal appearing cell nuclei in the treated region. This suggests that the normalized backscatter intensity may be a potential quantitative real-time feedback parameter for histotripsy-induced tissue fractionation. This quantitative feedback may allow the prediction of local clinical outcomes, i.e., when a tissue volume has been sufficiently treated. PMID:19750596

Quantitative ultrasound backscatter for pulsed cavitational ultrasound therapy- histotripsy.

PubMed

Wang, Tzu-yin; Xu, Zhen; Winterroth, Frank; Hall, Timothy L; Fowlkes, J Brian; Rothman, Edward D; Roberts, William W; Cain, Charles A

2009-05-01

Histotripsy is a well-controlled ultrasonic tissue ablation technology that mechanically and progressively fractionates tissue structures using cavitation. The fractionated tissue volume can be monitored with ultrasound imaging because a significant ultrasound backscatter reduction occurs.This paper correlates the ultrasound backscatter reduction with the degree of tissue fractionation characterized by the percentage of remaining normal-appearing cell nuclei on histology.Different degrees of tissue fractionation were generated in vitro in freshly excised porcine kidneys by varying the number of therapeutic ultrasound pulses from 100 to 2000 pulses per treatment location. All ultrasound pulses were 15 cycles at 1 MHz delivered at 100 Hz pulse repetition frequency and 19 MPa peak negative pressure. The results showed that the normalized backscatter intensity decreased exponentially with increasing number of pulses. Correspondingly, the percentage of normal appearing nuclei in the treated area decreased exponentially as well. A linear correlation existed between the normalized backscatter intensity and the percentage of normal appearing cell nuclei in the treated region. This suggests that the normalized backscatter intensity may be a potential quantitative real-time feedback parameter for histotripsy-induced tissue fractionation. This quantitative feedback may allow the prediction of local clinical outcomes, i.e., when a tissue volume has been sufficiently treated.

Traumatic globe luxation associated with orbital fracture in a child: a case report and literature review.

PubMed

Amaral, Márcio Bruno Figueiredo; Carvalho, Matheus Furtado; Ferreira, André Baptista; Mesquita, Ricardo Alves

2015-03-01

Orbital fracture associated with traumatic globe luxation is rare, as it generally requires trauma with high energy for this to occur. The present case report focused on a child who had been hit by a motorcycle, leading to a globe luxation of the left eye and fractures of the superolateral orbital walls. The patient presented initial cosmetic and psychological benefits from the repositioning of the intact globe and the reduction of the orbital fractures. However, a subsequent evisceration of the globe was required due to persistent proptosis and pain. An ocular prosthesis was also implanted, thus recovering the patient's aesthetics. Thirty-four well-documented cases of traumatic globe luxation could be found in the English literature since 1970. The mean age of patients presenting traumatic globe luxation was 29.5 years. The male gender proved to be more prevalent, with traffic collisions representing the most common accident etiology. Direct orbital trauma with fractures of medial and floor walls displacing the globe into the maxillary sinus represented the most common injury mechanism (38.2 %), followed by an elongated object entering the orbit (26.5 %). Optical nerve avulsion is the most serious complication seen in association with traumatic globe luxation, with the repositioning of the initial globe, with no enucleation or evisceration, representing the main form of management.

Seafloor Characterization from Spatial Variation of Multibeam Backscatter vs. Grazing Angle

NASA Astrophysics Data System (ADS)

hou, T.

2001-12-01

Backscatter vs. grazing angle, which can be extracted from multibeam backscatter data, depend on characteristics of the multibeam system and the angular responses of backscatter that are characteristic of different seafloor properties, such as sediment hardness and roughness. Changes in backscatter vs. grazing angle that are contributed by the multibeam system normally remain fixed over both space and time. Therefore, they can readily be determined and removed from backscatter data. The variation of backscatter vs. grazing angle due to the properties of sediments will vary from location to location, as sediment type changes. The sediment component of variability can be inferred using the redundant observations from different grazing angles in several small pieces of seafloor where the sediment property is uniform in any given piece of seafloor yet vary from one piece of the seafloor to another. Thanks to the multibeam survey (Roger Flood, State University of New York) at SAX 99 Project sponsored by Office of Naval Research (ONR), which had 800% coverage in most of the survey area; there is a data set, which is suitable for investigating seafloor characterization. The investigation analyzed the spatial variation of the backscatter vs. grazing angle and compared that with ground truth sediment data. In this research, the 6.9 gigabytes raw multibeam data were cleaned using an automated outlier detection algorithm (Tianhang Hou, Lloyd Huff and Larry Mayer. 2001). Then, the surveyed area was equally divided into 52X78 rectangle working cells (4056), the side of each cell was about 20 meters. The backscatter vs. grazing angle of backscatter data for each cell is computed by averaging backscatter data by the corresponding beam numbers using all data with the same beam number from different survey lines. Systematic effects on the backscatter vs. grazing angle, caused by multibeam system hardware or software as well as system installation, were corrected in order to remove

Laser Backscatter and Propagation in Low-Density Ta2O5 and SiO2 Foams

NASA Astrophysics Data System (ADS)

Mariscal, Derek; Patankar, Siddarth; Goyon, Clement; Baker, Kevin; MacLaren, Stephan; Hammer, Jim; Baumann, Ted; Amendt, Peter; Menapace, Joseph; Berger, Robert; Afeyan, Bedros; Tabak, Max; Kim, Sung Ho; Dixit, Sham; Moody, John; Jones, Ogden; LLNL Team; Polymath Research Inc. Collaboration

2016-10-01

Recent experiments at the Jupiter Laser Facility at LLNL have investigated the propagation and backscatter of a laser in low-density foams (2-30 mg/cc) comprised of Ta2O5 and SiO2. The foams fill the volume of thin polyimide tubes (2 mm diameter, 0.5-2 mm length), while the laser is directed down the axis of the tubes. Time-resolved Stimulated Brillouin Scattering (SBS) spectrum, time-integrated Stimulated Raman Scattering (SRS) spectrum and power were measured in the focusing cone. In addition Near Backscatter Imaging (NBI) assessed SBS outside the focusing cone while X-ray diagnostics were used to assess laser propagation through the foams. While this experiment uses a 2-omega laser drive, the pulse shape, irradiance, and the ratio ne/nc are scaled to be similar to future tests using Ta2O5 foams at the NIF. Experimental results are directly compared to calculations of laser propagation and backscattered spectra. This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, with funding support from the Laboratory Directed Research and Development Program 15-ERD-073.

Quantitative Analysis of Venus Radar Backscatter Data in ArcGIS

NASA Technical Reports Server (NTRS)

Long, S. M.; Grosfils, E. B.

2005-01-01

Ongoing mapping of the Ganiki Planitia (V14) quadrangle of Venus and definition of material units has involved an integrated but qualitative analysis of Magellan radar backscatter images and topography using standard geomorphological mapping techniques. However, such analyses do not take full advantage of the quantitative information contained within the images. Analysis of the backscatter coefficient allows a much more rigorous statistical comparison between mapped units, permitting first order selfsimilarity tests of geographically separated materials assigned identical geomorphological labels. Such analyses cannot be performed directly on pixel (DN) values from Magellan backscatter images, because the pixels are scaled to the Muhleman law for radar echoes on Venus and are not corrected for latitudinal variations in incidence angle. Therefore, DN values must be converted based on pixel latitude back to their backscatter coefficient values before accurate statistical analysis can occur. Here we present a method for performing the conversions and analysis of Magellan backscatter data using commonly available ArcGIS software and illustrate the advantages of the process for geological mapping.

Investigation of the optimal backscatter for an aSi electronic portal imaging device.

PubMed

Ko, Lung; Kim, Jong Oh; Siebers, Jeffrey V

2004-05-07

The effects of backscattered radiation on the dosimetric response of the Varian aS500 amorphous silicon electronic portal imaging device (EPID) are studied. Measurements demonstrate that radiation backscattered from the EPID mechanical support structure causes 5% asymmetries in the detected signal. To minimize the effect of backscattered radiation from the support structure, this work proposes adding material downstream of the EPID phosphor which provides uniform backscattering material to the phosphor and attenuates backscatter from the support structure before it reaches the phosphor. Two material locations were studied: downstream of the existing image cassette and within the cassette, immediately downstream of the flat-panel imager glass panel. Monte Carlo simulations were used to determine the thicknesses of water, Pb and Cu backscattering materials required to saturate the backscattered signal response for 6 MV and 18 MV beams for material thicknesses up to 50 mm. Water was unable to saturate the backscattered signal for thicknesses up to 50 mm for both energies. For Pb, to obtain a signal within 1% of saturation, 3 mm was required at 6 MV, and 6.8 mm was required at 18 MV. For Cu, thicknesses of 20.6 mm and 22.6 mm were required for the 6 MV and 18 MV beams, respectively. For saturation thicknesses, at 6 MV, the Cu backscatter enhanced the signal more than for Pb (Cu 1.25, Pb 1.11), but at 18 MV the reverse was found (Cu 1.19, Pb 1.23). This is due to the fact that at 6 MV, the backscattered radiation signal is dominated by low-energy scattered photons, which are readily attenuated by the Pb, while at 18 MV, electron backscatter contributes substantially to the signal. Image blurring caused by backscatter spread was less for Pb than Cu. Placing Pb immediately downstream of the glass panel further reduced the signal spread and increased the backscatter enhancement to 1.20 and 1.39 for the 6 MV and 18 MV beams, respectively. Overall, it is determined that

Quantifying Fish Backscattering using SONAR Instrument and Kirchhoff Ray Mode (KRM) Model

NASA Astrophysics Data System (ADS)

Manik, Henry M.

2016-08-01

Sonar instrument was used to study backscattering from tuna fish. Extraction of target strength, incidence angle, and frequency dependence of the backscattered signal for individual scatterer was important for biological information. For this purpose, acoustic measurement of fish backscatter was conducted in the laboratory. Characteristics and general trends of the target strength of fish with special reference to tuna fish were investigated by using a Kirchhoff Ray Mode (KRM) model. Backscattering strength were calculated for the KRM having typical morphological and physical parameters of actual fish. Those backscattering amplitudes were shown as frequency, body length, backscattering patterns, the density and sound speed dependences, and orientation dependence. These results were compared with experimentally measured target strength data and good agreement was found. Measurement and model showed the target strength from the fish are depend on the presence of swimbladder. Target Strength increase with increasing the frequency and fish length.

Simulation of radar backscattering from snowpack at X-band and Ku-band

NASA Astrophysics Data System (ADS)

Gay, Michel; Phan, Xuan-Vu; Ferro-Famil, Laurent

2016-04-01

This paper presents a multilayer snowpack electromagnetic backscattering model, based on Dense Media Radiative Transfer (DMRT). This model is capable of simulating the interaction of electromagnetic wave (EMW) at X-band and Ku-band frequencies with multilayer snowpack. The air-snow interface and snow-ground backscattering components are calculated using the Integral Equation Model (IEM) by [1], whereas the volume backscattering component is calculated based on the solution of Vector Radiative Transfer (VRT) equation at order 1. Case study has been carried out using measurement data from NoSREx project [2], which include SnowScat data in X-band and Ku-band, TerraSAR-X acquisitions and snowpack stratigraphic in-situ measurements. The results of model simulations show good agreement with the radar observations, and therefore allow the DMRT model to be used in various applications, such as data assimilation [3]. [1] A.K. Fung and K.S. Chen, "An update on the iem surface backscattering model," Geoscience and Remote Sensing Letters, IEEE, vol. 1, no. 2, pp. 75 - 77, april 2004. [2] J. Lemmetyinen, A. Kontu, J. Pulliainen, A. Wiesmann, C. Werner, T. Nagler, H. Rott, and M. Heidinger, "Technical assistance for the deployment of an x- to ku-band scatterometer during the nosrex ii experiment," Final Report, ESA ESTEC Contract No. 22671/09/NL/JA., 2011. [3] X. V. Phan, L. Ferro-Famil, M. Gay, Y. Durand, M. Dumont, S. Morin, S. Allain, G. D'Urso, and A. Girard, "3d-var multilayer assimilation of x-band sar data into a detailed snowpack model," The Cryosphere Discussions, vol. 7, no. 5, pp. 4881-4912, 2013.

GLOBE Observer: A new tool to bring science activities and measurements home

NASA Astrophysics Data System (ADS)

Riebeek Kohl, H.; Murphy, T.

2016-12-01

The Global Learning and Observations to Benefit the Environment (GLOBE) Program is an international science and education program that provides students and the public worldwide with the opportunity to participate in data collection and the scientific process, and contribute meaningfully to our understanding of the Earth system and global environment. For more than 20 years, GLOBE-trained teachers have been leading environmental data collection and student research in the classroom. In 2016, GLOBE expanded to invite data collection from citizen scientists of all ages through a simple smart phone app. The app makes it possible for students to take GLOBE data (environmental observations) outside of school with their families. It enables a museum, park, youth organization, or other informal institution to provide a simple take-home activity that will keep patrons engaged in environmental science from home. This presentation will provide a demonstration of the app and will provide examples of its use in informal settings.

Backscattering Measurement From a Single Microdroplet

PubMed Central

Lee, Jungwoo; Chang, Jin Ho; Jeong, Jong Seob; Lee, Changyang; Teh, Shia-Yen; Lee, Abraham; Shung, K. Kirk

2011-01-01

Backscattering measurements for acoustically trapped lipid droplets were undertaken by employing a P[VDF-TrFE] broadband transducer of f-number = 1, with a bandwidth of 112%. The wide bandwidth allowed the transmission of the 45 MHz trapping signal and the 15 MHz sensing signal using the same transducer. Tone bursts at 45 MHz were first transmitted by the transducer to hold a single droplet at the focus (or the center of the trap) and separate it from its neighboring droplets by translating the transducer perpendicularly to the beam axis. Subsequently, 15 MHz probing pulses were sent to the trapped droplet and the backscattered RF echo signal received by the same transducer. The measured beam width at 15 MHz was measured to be 120 μm. The integrated backscatter (IB) coefficient of an individual droplet was determined within the 6-dB bandwidth of the transmit pulse by normalizing the power spectrum of the RF signal to the reference spectrum obtained from a flat reflector. The mean IB coefficient for droplets with a 64 μm average diameter (denoted as cluster A) was −107 dB, whereas it was −93 dB for 90-μm droplets (cluster B). The standard deviation was 0.9 dB for each cluster. The experimental values were then compared with those computed with the T-matrix method and a good agreement was found: the difference was as small as 1 dB for both clusters. These results suggest that this approach might be useful as a means for measuring ultrasonic backscattering from a single microparticle, and illustrate the potential of acoustic sensing for cell sorting. PMID:21507767

Analysis of the Dryden Wet Bulb GLobe Temperature Algorithm for White Sands Missile Range

NASA Technical Reports Server (NTRS)

LaQuay, Ryan Matthew

2011-01-01

In locations where workforce is exposed to high relative humidity and light winds, heat stress is a significant concern. Such is the case at the White Sands Missile Range in New Mexico. Heat stress is depicted by the wet bulb globe temperature, which is the official measurement used by the American Conference of Governmental Industrial Hygienists. The wet bulb globe temperature is measured by an instrument which was designed to be portable and needing routine maintenance. As an alternative form for measuring the wet bulb globe temperature, algorithms have been created to calculate the wet bulb globe temperature from basic meteorological observations. The algorithms are location dependent; therefore a specific algorithm is usually not suitable for multiple locations. Due to climatology similarities, the algorithm developed for use at the Dryden Flight Research Center was applied to data from the White Sands Missile Range. A study was performed that compared a wet bulb globe instrument to data from two Surface Atmospheric Measurement Systems that was applied to the Dryden wet bulb globe temperature algorithm. The period of study was from June to September of2009, with focus being applied from 0900 to 1800, local time. Analysis showed that the algorithm worked well, with a few exceptions. The algorithm becomes less accurate to the measurement when the dew point temperature is over 10 Celsius. Cloud cover also has a significant effect on the measured wet bulb globe temperature. The algorithm does not show red and black heat stress flags well due to shorter time scales of such events. The results of this study show that it is plausible that the Dryden Flight Research wet bulb globe temperature algorithm is compatible with the White Sands Missile Range, except for when there are increased dew point temperatures and cloud cover or precipitation. During such occasions, the wet bulb globe temperature instrument would be the preferred method of measurement. Out of the 30

Acoustic backscatter of the 1995 flood deposit on the Eel shelf

USGS Publications Warehouse

Borgeld, J.C.; Hughes-Clarke, John E.; Goff, John A.; Mayer, Larry A.; Curtis, Jennifer A.

1999-01-01

Acoustic swath mapping and sediment box coring conducted on the continental shelf near the mouth of the Eel River revealed regional variations in acoustic backscatter that can be related to the shelf sedimentology. The acoustic-backscatter variations observed on the shelf were unusually narrow compared to the response of similar sediment types documented in other areas. However, the acoustic data revealed four principal bottom types on the shelf that can be related to sedimentologic differences observed in cores. The four areas are: (1) low acoustic backscatter associated with the nearshore-sand facies and the prodelta terraces of the Eel and Mad rivers, composed of fine sands and coarse silts with low porosity; (2) high acoustic backscatter associated with fine silts characterized by high porosity and deposited by the 1995 flood of the Eel River; (3) intermediate acoustic backscatter in the outer-shelf muds, where clayey silts are accumulating and the 1995 flood apparently had limited direct effect; and (4) intermediate acoustic backscatter near the fringes of the 1995 flood deposits and in areas where the flood sediments were more disrupted by post-depositional processes. The highest acoustic backscatter was identified in areas where the 1995 flood sediments remained relatively intact and near the shelf surface into the summer of 1995. Cores collected from these areas contained wavy or lenticular bedding. The rapid deposition of the high-porosity muddy layers results in better preservation of incorporated ripple forms than in areas less directly impacted by the flood deposit. The high-porosity muddy layers allow acoustic penetration into the sediments and result in greater acoustic backscatter from incorporated roughness elements.

2D Doppler backscattering using synthetic aperture microwave imaging of MAST edge plasmas

NASA Astrophysics Data System (ADS)

Thomas, D. A.; Brunner, K. J.; Freethy, S. J.; Huang, B. K.; Shevchenko, V. F.; Vann, R. G. L.

2016-02-01

Doppler backscattering (DBS) is already established as a powerful diagnostic; its extension to 2D enables imaging of turbulence characteristics from an extended region of the cut-off surface. The Synthetic Aperture Microwave Imaging (SAMI) diagnostic has conducted proof-of-principle 2D DBS experiments of MAST edge plasma. SAMI actively probes the plasma edge using a wide (±40° vertical and horizontal) and tuneable (10-34.5 GHz) beam. The Doppler backscattered signal is digitised in vector form using an array of eight Vivaldi PCB antennas. This allows the receiving array to be focused in any direction within the field of view simultaneously to an angular range of 6-24° FWHM at 10-34.5 GHz. This capability is unique to SAMI and is a novel way of conducting DBS experiments. In this paper the feasibility of conducting 2D DBS experiments is explored. Initial observations of phenomena previously measured by conventional DBS experiments are presented; such as momentum injection from neutral beams and an abrupt change in power and turbulence velocity coinciding with the onset of H-mode. In addition, being able to carry out 2D DBS imaging allows a measurement of magnetic pitch angle to be made; preliminary results are presented. Capabilities gained through steering a beam using a phased array and the limitations of this technique are discussed.

Light backscattering efficiency and related properties of some phytoplankters

NASA Astrophysics Data System (ADS)

Ahn, Yu-Hwan; Bricaud, Annick; Morel, André

1992-11-01

By using a set-up that combines an integrating sphere with a spectroradiometer LI-1800 UW, the backscattering properties of nine different phytoplankters grown in culture have been determined experimentally for the wavelengths domain ν = 400 up to 850 nm. Simultaneously, the absorption and attenuation properties, as well as the size distribution function, have been measured. This set of measurements allowed the spectral values of refractive index, and subsequently the volume scattering functions (VSF) of the cells, to be derived, by operating a scattering model previously developed for spherical and homogeneous cells. The backscattering properties, measured within a restricted angular domain (approximately between 132 and 174°), have been compared to theoretical predictions. Although there appear some discrepancies between experimental and predicted values (probably due to experimental errors as well as deviations of actual cells from computational hypotheses), the overall agreement is good; in particular the observed interspecific variations of backscattering values, as well as the backscattering spectral variation typical of each species, are well accounted for by theory. Using the computed VSF, the measured backscattering properties can be converted (assuming spherical and homogeneous cells) into efficiency factors for backscattering ( overlineQbb) . Thhe spectral behavior of overlineQbb appears to be radically different from that for total scattering overlineQb. For small cells, overlineQ (λ) is practically constant over the spectrum, whereas overlineQb(λ) varies approximately according to a power law (λ -2). As the cell size increases, overlineQbb conversely, becomes increasingly featured, whilst overlineQb becomes spectrally flat. The chlorophyll-specific backscattering coefficients ( b b∗ appear highly variable and span nearly two orders of magnitude. The chlorophyll-specific absorption and scattering coefficients, a ∗ and b ∗, are mainly ruled by

Globe, student inquiry, and learning communities

Treesearch

C.L. Henzel

2000-01-01

The Global Learning and Observations to Benefit the Environment (GLOBE) database is a web-based archive of environmental data gathered by K through 12 students in over 85 countries. The data are gathered under protocols developed by research scientists specializing in various fields of earth science. Students gather information, then enter and visualize the data via...

Surgery of the globe and orbit.

PubMed

Cho, Jane

2008-02-01

Orbital anatomy and the indications and surgical techniques for a variety of small animal orbital/globe surgical procedures are discussed. Details of the more common orbital surgical procedures, including ocular evisceration, intrascleral prosthesis implantation, enucleation, and proptosis repair, are given. Common complications and postoperative considerations for these procedures are also discussed with an emphasis on the practical aspects.

Dagik Earth: A Digital Globe Project for Classrooms, Science Museums, and Research Institutes

NASA Astrophysics Data System (ADS)

Saito, A.; Tsugawa, T.

2017-12-01

Digital globe system is a powerful tool to make the audiences understand phenomena on the Earth and planets in intuitive way. Geo-cosmos of Miraikan, Japan uses 6-m spherical LED, and is one of the largest systems of digital globe. Science on a Sphere (SOS) by NOAA is a digital globe system that is most widely used in science museums around the world. These systems are so expensive that the usage of the digital globes is mainly limited to large-scale science museums. Dagik Earth is a digital globe project that promotes educational programs using digital globe with low cost. It aims to be used especially in classrooms. The cost for the digital globe of Dagik Earth is from several US dollars if PC and PC projector are available. It uses white spheres, such as balloons and balance balls, as the screen. The software is provided by the project with free of charge for the educational usage. The software runs on devices of Windows, Mac and iOS. There are English and Chinese language versions of the PC software besides Japanese version. The number of the registered users of Dagik Earth is about 1,400 in Japan. About 60% of them belongs to schools, 30% to universities and research institutes, and 8% to science museums. In schools, it is used in classes by teachers, and science activities by students. Several teachers have used the system for five years and more. In a students' activity, Dagik Earth contents on the typhoon, solar eclipse, and satellite launch were created and presented in a school festival. This is a good example of the usage of Dagik Earth for STEM education. In the presentation, the system and activity of Dagik Earth will be presented, and the future expansion of the project will be discussed.

Retrieval of Ocean Subsurface Particulate Backscattering Coefficient from Space-Borne CALIOP Lidar Measurement

NASA Technical Reports Server (NTRS)

Lu, Xiaomei; Hu, Yongxiang; Pelon, Jacques; Trepte, Chip; Liu, Katie; Rodier, Sharon; Zeng, Shan; Luckher, Patricia; Verhappen, Ron; Wilson, Jamie;

Relating multifrequency radar backscattering to forest biomass: Modeling and AIRSAR measurement

NASA Technical Reports Server (NTRS)

Sun, Guo-Qing; Ranson, K. Jon

1992-01-01

During the last several years, significant efforts in microwave remote sensing were devoted to relating forest parameters to radar backscattering coefficients. These and other studies showed that in most cases, the longer wavelength (i.e. P band) and cross-polarization (HV) backscattering had higher sensitivity and better correlation to forest biomass. This research examines this relationship in a northern forest area through both backscatter modeling and synthetic aperture radar (SAR) data analysis. The field measurements were used to estimate stand biomass from forest weight tables. The backscatter model described by Sun et al. was modified to simulate the backscattering coefficients with respect to stand biomass. The average number of trees per square meter or radar resolution cell, and the average tree height or diameter breast height (dbh) in the forest stand are the driving parameters of the model. The rest of the soil surface, orientation, and size distributions of leaves and branches, remain unchanged in the simulations.

The effect of leaf size on the microwave backscattering by corn

NASA Technical Reports Server (NTRS)

Paris, J. F.

1986-01-01

Attema and Ulaby (1978) proposed the cloud model to predict the microwave backscattering properties of vegetation. This paper describes a modification in which the biophysical properties and microwave properties of vegetation are related at the level of the individual scatterer (e.g., the leaf or the stalk) rather than at the level of the aggregated canopy (e.g., the green leaf area index). Assuming that the extinction cross section of an average leaf was proportional to its water content, that a power law relationship existed between the backscattering cross section of an average green corn leaf and its area, and that the backscattering coefficient of the surface was a linear function of its volumetric soil moisture content, it is found that the explicit inclusion of the effects of corn leaf size in the model led to an excellent fit between the observed and predicted backscattering coefficients. Also, an excellent power law relationship existed between the backscattering cross section of a corn leaf and its area.

Probabilities and statistics for backscatter estimates obtained by a scatterometer

NASA Technical Reports Server (NTRS)

Pierson, Willard J., Jr.

1989-01-01

Methods for the recovery of winds near the surface of the ocean from measurements of the normalized radar backscattering cross section must recognize and make use of the statistics (i.e., the sampling variability) of the backscatter measurements. Radar backscatter values from a scatterometer are random variables with expected values given by a model. A model relates backscatter to properties of the waves on the ocean, which are in turn generated by the winds in the atmospheric marine boundary layer. The effective wind speed and direction at a known height for a neutrally stratified atmosphere are the values to be recovered from the model. The probability density function for the backscatter values is a normal probability distribution with the notable feature that the variance is a known function of the expected value. The sources of signal variability, the effects of this variability on the wind speed estimation, and criteria for the acceptance or rejection of models are discussed. A modified maximum likelihood method for estimating wind vectors is described. Ways to make corrections for the kinds of errors found for the Seasat SASS model function are described, and applications to a new scatterometer are given.

Optimal Time Allocation in Backscatter Assisted Wireless Powered Communication Networks.

PubMed

Lyu, Bin; Yang, Zhen; Gui, Guan; Sari, Hikmet

2017-06-01

This paper proposes a wireless powered communication network (WPCN) assisted by backscatter communication (BackCom). This model consists of a power station, an information receiver and multiple users that can work in either BackCom mode or harvest-then-transmit (HTT) mode. The time block is mainly divided into two parts corresponding to the data backscattering and transmission periods, respectively. The users first backscatter data to the information receiver in time division multiple access (TDMA) during the data backscattering period. When one user works in the BackCom mode, the other users harvest energy from the power station. During the data transmission period, two schemes, i.e., non-orthogonal multiple access (NOMA) and TDMA, are considered. To maximize the system throughput, the optimal time allocation policies are obtained. Simulation results demonstrate the superiority of the proposed model.

Optimal Time Allocation in Backscatter Assisted Wireless Powered Communication Networks

PubMed Central

Lyu, Bin; Yang, Zhen; Gui, Guan; Sari, Hikmet

2017-01-01

This paper proposes a wireless powered communication network (WPCN) assisted by backscatter communication (BackCom). This model consists of a power station, an information receiver and multiple users that can work in either BackCom mode or harvest-then-transmit (HTT) mode. The time block is mainly divided into two parts corresponding to the data backscattering and transmission periods, respectively. The users first backscatter data to the information receiver in time division multiple access (TDMA) during the data backscattering period. When one user works in the BackCom mode, the other users harvest energy from the power station. During the data transmission period, two schemes, i.e., non-orthogonal multiple access (NOMA) and TDMA, are considered. To maximize the system throughput, the optimal time allocation policies are obtained. Simulation results demonstrate the superiority of the proposed model. PMID:28587171

X-Ray Backscatter Imaging for Aerospace Applications

NASA Astrophysics Data System (ADS)

Shedlock, Daniel; Edwards, Talion; Toh, Chin

2011-06-01

Scatter x-ray imaging (SXI) is a real time, digital, x-ray backscatter imaging technique that allows radiographs to be taken from one side of an object. This x-ray backscatter imaging technique offers many advantages over conventional transmission radiography that include single-sided access and extremely low radiation fields compared to conventional open source industrial radiography. Examples of some applications include the detection of corrosion, foreign object debris, water intrusion, cracking, impact damage and leak detection in a variety of material such as aluminum, composites, honeycomb structures, and titanium.

Interference phenomena at backscattering by ice crystals of cirrus clouds.

PubMed

Borovoi, Anatoli; Kustova, Natalia; Konoshonkin, Alexander

2015-09-21

It is shown that light backscattering by hexagonal ice crystals of cirrus clouds is formed within the physical-optics approximation by both diffraction and interference phenomena. Diffraction determines the angular width of the backscattering peak and interference produces the interference rings inside the peak. By use of a simple model for distortion of the pristine hexagonal shape, we show that the shape distortion leads to both oscillations of the scattering (Mueller) matrix within the backscattering peak and to a strong increase of the depolarization, color, and lidar ratios needed for interpretation of lidar signals.

CO2 lidar backscatter profiles over Hawaii during fall 1988

NASA Technical Reports Server (NTRS)

Post, Madison J.; Cupp, Richard E.

1992-01-01

Aerosol and cloud backscatter data, obtained over a 24-day period in fall 1988 with the National Oceanic and Atmospheric Administration's Doppler lidar at 10.59-micron wavelength, are analyzed by using a new technique to lessen biases that are due to dropouts. Typical backscatter cross sections were significantly lower than those routinely observed over the continental United States, although episodic backscatter enhancements caused by cirrus and mineral dust also occurred. Implications of these data on the proposed Laser Atmospheric Wind Sounder wind profiling satellite sensor are discussed.

Electromagnetic backscattering by corner reflectors

NASA Technical Reports Server (NTRS)

Balanis, C. A.; Griesser, T.

1986-01-01

The Geometrical Theory of Diffraction (GTD), which supplements Geometric Optics (GO), and the Physical Theory of Diffraction (PTD), which supplements Physical Optics (PO), are used to predict the backscatter cross sections of dihedral corner reflectors which have right, obtuse, or acute included angles. These theories allow individual backscattering mechanisms of the dihedral corner reflectors to be identified and provide good agreement with experimental results in the azimuthal plane. The advantages and disadvantages of the geometrical and physical theories are discussed in terms of their accuracy, usefulness, and complexity. Numerous comparisons of analytical results with experimental data are presented. While physical optics alone is more accurate and more useful than geometrical optics alone, the combination of geometrical optics and geometrical diffraction seems to out perform physical optics and physical diffraction when compared with experimental data, especially for acute angle dihedral corner reflectors.

Backscatter and attenuation characterization of ventricular myocardium

NASA Astrophysics Data System (ADS)

Gibson, Allyson Ann

2009-12-01

This Dissertation presents quantitative ultrasonic measurements of the myocardium in fetal hearts and adult human hearts with the goal of studying the physics of sound waves incident upon anisotropic and inhomogeneous materials. Ultrasound has been used as a clinical tool to assess heart structure and function for several decades. The clinical usefulness of this noninvasive approach has grown with our understanding of the physical mechanisms underlying the interaction of ultrasonic waves with the myocardium. In this Dissertation, integrated backscatter and attenuation analyses were performed on midgestational fetal hearts to assess potential differences in the left and right ventricular myocardium. The hearts were interrogated using a 50 MHz transducer that enabled finer spatial resolution than could be achieved at more typical clinical frequencies. Ultrasonic data analyses demonstrated different patterns and relative levels of backscatter and attenuation from the myocardium of the left ventricle and the right ventricle. Ultrasonic data of adult human hearts were acquired with a clinical imaging system and quantified by their magnitude and time delay of cyclic variation of myocardial backscatter. The results were analyzing using Bayes Classification and ROC analysis to quantify potential advantages of using a combination of two features of cyclic variation of myocardial backscatter over using only one or the other feature to distinguish between groups of subjects. When the subjects were classified based on hemoglobin A1c, the homeostasis model assessment of insulin resistance, and the ratio of triglyceride to high-density lipoprotein-cholesterol, differences in the magnitude and normalized time delay of cyclic variation of myocardial backscatter were observed. The cyclic variation results also suggested a trend toward a larger area under the ROC curve when information from magnitude and time delay of cyclic variation is combined using Bayes classification than when

Application of HARLIE Measurements in Mesoscale Studies: Measurements of Aerosol Backscatter and Winds During A Gust Front

NASA Technical Reports Server (NTRS)

Demoz, Belay; Miller, David; Schwemmer, Geary; Starr, David OC (Technical Monitor)

2001-01-01

Lidar atmospheric systems have required large telescope for receiving atmospheric backscatter signals. Thus, the relative complexity in size and ease of operation has limited their wider use in the atmospheric science and meteorology community. The Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE) uses a scanning holographic receiver and demonstrates that these issues can be overcome. HARLIE participated at the DOE-ARM Southern Great Plains site (CART) during the Water Vapor Intensive Operation Period (WVIOP2000) held September-October 2000. It provided exceptional high temporal and spatial resolution measurements of aerosol and cloud backscatter in three dimensions. HARLIE recorded over 110 hours of data were recorded on 16 days between 17 September and 6 October 2000. Placed in a ground-based trailer for upward looking scanning measurements of clouds and aerosols, HARLIE provided a unique record of time-resolved atmospheric backscatter at 1-micron wavelength. The conical scanning lidar measures atmospheric backscatter on the surface of an inverted 90 degree (full angle) cone up to an altitude of 20 km, 360-degree scans having spatial resolutions of 20 meters in the vertical and 1 degree in azimuth were obtained every 36 seconds during the daily, operating period. In this study we present highlights of HARLIE-based measurements of the boundary layer and cloud parameters as well as atmospheric wind vectors where there is sufficiently resolved structure in the backscatter. In particular we present data and discussions from a bore-front case observed on 23 September 2000.

Circularly polarized measurements of radar backscatter from terrain

NASA Astrophysics Data System (ADS)

Wilson, E. A.; Brunfeldt, D. R.; Ulaby, F. T.; Holtzman, J. C.

1980-02-01

This report documents the design changes to the University of Kansas MAS 8-18/35 scatterometer system required to incorporate a circular polarization capability and a subsequent backscatter measurement program. The modifications enable the MAS 8-18/35 system to acquire both linear (HH, HV, VV) and circular (RR, RL, LL) radar backscatter data over its entire operating range of 8-18 GHz and 35 GHz. The measurement program described herein consisted of measurements of the backscatter coefficient, as a function of the angle of incidence (0-80) at selected frequencies in the 8-18 GHz range using circular polarization. Targets studied included coniferous and deciduous trees, wet and dry asphalt and concrete and bare and plowed ground at various moisture conditions. Coniferous and deciduous tree measurements were taken in both August and November so that seasonal changes could be observed.

Calculations of radar backscattering coefficient of vegetation-covered soils

NASA Technical Reports Server (NTRS)

Mo, T.; Schmugge, T. J.; Jackson, T. J. (Principal Investigator)

1983-01-01

A model for simulating the measured backscattering coefficient of vegetation-covered soil surfaces includes both coherent and incoherent components of the backscattered radar pulses from a rough sil surface. The effect of vegetation canopy scattering is also incorporated into the model by making the radar pulse subject to two-way attenuation and volume scattering when it passes through the vegetation layer. Model results agree well with the measured angular distributions of the radar backscattering coefficient for HH polarization at the 1.6 GHz and 4.75 GHz frequencies over grass-covered fields. It was found that the coherent scattering component is very important at angles near nadir, while the vegetation volume scattering is dominant at incident angles 30 degrees.

Interactive Visualization and Analysis of Geospatial Data Sets - TrikeND-iGlobe

NASA Astrophysics Data System (ADS)

Rosebrock, Uwe; Hogan, Patrick; Chandola, Varun

2013-04-01

The visualization of scientific datasets is becoming an ever-increasing challenge as advances in computing technologies have enabled scientists to build high resolution climate models that have produced petabytes of climate data. To interrogate and analyze these large datasets in real-time is a task that pushes the boundaries of computing hardware and software. But integration of climate datasets with geospatial data requires considerable amount of effort and close familiarity of various data formats and projection systems, which has prevented widespread utilization outside of climate community. TrikeND-iGlobe is a sophisticated software tool that bridges this gap, allows easy integration of climate datasets with geospatial datasets and provides sophisticated visualization and analysis capabilities. The objective for TrikeND-iGlobe is the continued building of an open source 4D virtual globe application using NASA World Wind technology that integrates analysis of climate model outputs with remote sensing observations as well as demographic and environmental data sets. This will facilitate a better understanding of global and regional phenomenon, and the impact analysis of climate extreme events. The critical aim is real-time interactive interrogation. At the data centric level the primary aim is to enable the user to interact with the data in real-time for the purpose of analysis - locally or remotely. TrikeND-iGlobe provides the basis for the incorporation of modular tools that provide extended interactions with the data, including sub-setting, aggregation, re-shaping, time series analysis methods and animation to produce publication-quality imagery. TrikeND-iGlobe may be run locally or can be accessed via a web interface supported by high-performance visualization compute nodes placed close to the data. It supports visualizing heterogeneous data formats: traditional geospatial datasets along with scientific data sets with geographic coordinates (NetCDF, HDF, etc

Comparison of radar backscatter from Antarctic and Arctic sea ice

NASA Technical Reports Server (NTRS)

Hosseinmostafa, R.; Lytle, V.

1992-01-01

Two ship-based step-frequency radars, one at C-band (5.3 GHz) and one at Ku-band (13.9 GHz), measured backscatter from ice in the Weddell Sea. Most of the backscatter data were from first-year (FY) and second-year (SY) ice at the ice stations where the ship was stationary and detailed snow and ice characterizations were performed. The presence of a slush layer at the snow-ice interface masks the distinction between FY and SY ice in the Weddell Sea, whereas in the Arctic the separation is quite distinct. The effect of snow-covered ice on backscattering coefficients (sigma0) from the Weddell Sea region indicates that surface scattering is the dominant factor. Measured sigma0 values were compared with Kirchhoff and regression-analysis models. The Weibull power-density function was used to fit the measured backscattering coefficients at 45 deg.

Reconsidering the Role of Artifacts in Reasoning: Children's Understanding of the Globe as a Model of the Earth

ERIC Educational Resources Information Center

Vosniadou, Stella; Skopeliti, Irini; Ikospentaki, Kalliopi

2005-01-01

This experiment investigated the effect of the presentation of a globe--the culturally accepted artifact representing the earth--on children's reasoning in elementary astronomy. Forty-four children from grades 1 and 3 were interviewed individually. First, the children were asked to make their own representations of the earth (i.e., drawings and…

Results from the Prototype GLOBE at Night Worldwide Light Pollution Observation Program

NASA Astrophysics Data System (ADS)

Walker, Constance E.; Pompea, S. M.; Isbell, D.; Orellana, D.; Blurton, C.; Henderson, S.

2006-06-01

Students, families, and educators worldwide participated in GLOBE at Night - an international event designed to observe and record the visible stars as a means of measuring light pollution in a given location. Participation was open to anyone - anywhere in the world - who could get outside and look skyward during the week of March 22-29, 2006. Our goal was 5000 observations from around the world in this prototype program.The hands-on learning activities associated with the program were designed to extend the traditional classroom and school day with a week of nighttime observations involving teachers, students and their families. By locating specific constellations in the sky, students from around the world learned how the lights in their community contribute to light pollution. Students explored the different light sources in their community learning the relationship between science, technology and society, and they reported their observations online through a central database allowing for authentic worldwide research and analysis. The observations made during GLOBE at Night helped students and scientists together assess how the quality of the night sky varies around the world as well as the level of energy wastage associated with poorly-shielded lights.For more information, visit http://www.globe.gov/globeatnight.GLOBE at Night is a collaboration between The GLOBE Program, the National Optical Astronomy Observatory (NOAO), Centro de Apoyo a la Didactica de la Astronomia (CADIAS) in Chile , Windows to the Universe, and Environmental Systems Research Institute, Inc. (ESRI).

The growth and decay of equatorial backscatter plumes

NASA Astrophysics Data System (ADS)

Tsunoda, R. T.

1980-02-01

During the past three years, a series of rocket experiments from the Kwajalein Atoll, Marshall Islands, were conducted to investigate the character of intense, scintillation-producing irregularities that occur in the nighttime equatorial ionosphere. Because the source mechanism of equatorial irregularities, believed to be the Rayleigh-Taylor instability, is analogous to that which generates plasma-density striations in a nuclear-induced environment, there is considerable interest in the underlying physics that controls the characteristics of these irregularities. A primary objective of ALTAIR investigations of equatorial irregularities is to seek an understanding of the underlying physics by establishing the relationship between meter-scale irregularities (detected by ALTAIR), and the large-scale plasma-density depletions (or 'bubbles') that contain the kilometer-scale, scintillation-producing irregularities. We describe the time evolution of backscatter 'plumes' produced by one meter equatorial field-aligned irregularities. Using ALTAIR, a fully steerable backscatter radar, to repeatedly map selected plumes, we characterize the dynamic behavior of plumes in terms of growth and a decay phase. Most of the observed characteristics are found to be consistent with equatorial-irregularity generation predicted by current theories of Rayleigh-Taylor and gradient-drift instabilities. However, other characteristics have been found that suggest key roles played by the eastward neutral wind and by altitude-modulation of the bottomside F layer in establishing the initial conditions for plume growth.

High Resolution Globe of Jupiter

NASA Image and Video Library

2001-01-30

This true-color simulated view of Jupiter is composed of 4 images taken by NASA's Cassini spacecraft on December 7, 2000. To illustrate what Jupiter would have looked like if the cameras had a field-of-view large enough to capture the entire planet, the cylindrical map was projected onto a globe. The resolution is about 144 kilometers (89 miles) per pixel. Jupiter's moon Europa is casting the shadow on the planet. https://photojournal.jpl.nasa.gov/catalog/PIA02873

Backscatter laser depolarization studies of simulated stratospheric aerosols - Crystallized sulfuric acid droplets

NASA Technical Reports Server (NTRS)

Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun

1989-01-01

The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystalization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

Backscatter laser depolarization studies of simulated stratospheric aerosols: Crystallized sulfuric acid droplets

NASA Technical Reports Server (NTRS)

Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun

1988-01-01

The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystallization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

Bathymetry and acoustic backscatter: Estero Bay, California

USGS Publications Warehouse

Hartwell, Stephen R.; Finlayson, David P.; Dartnell, Peter; Johnson, Samuel Y.

2013-01-01

Between July 30 and August 9, 2012, scientists from the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC), acquired bathymetry and acoustic-backscatter data from Estero Bay, San Luis Obispo, California, under PCMSC Field Activity ID S-05-12-SC. The survey was done using the R/V Parke Snavely outfitted with a multibeam sonar for swath mapping and highly accurate position and orientation equipment for georeferencing. This report provides these data in a number of different formats, as well as a summary of the mapping mission, maps of bathymetry and backscatter, and Federal Geographic Data Committee (FGDC) metadata.

Planning and Management of Real-Time Geospatialuas Missions Within a Virtual Globe Environment

NASA Astrophysics Data System (ADS)

Nebiker, S.; Eugster, H.; Flückiger, K.; Christen, M.

2011-09-01

This paper presents the design and development of a hardware and software framework supporting all phases of typical monitoring and mapping missions with mini and micro UAVs (unmanned aerial vehicles). The developed solution combines state-of-the art collaborative virtual globe technologies with advanced geospatial imaging techniques and wireless data link technologies supporting the combined and highly reliable transmission of digital video, high-resolution still imagery and mission control data over extended operational ranges. The framework enables the planning, simulation, control and real-time monitoring of UAS missions in application areas such as monitoring of forest fires, agronomical research, border patrol or pipeline inspection. The geospatial components of the project are based on the Virtual Globe Technology i3D OpenWebGlobe of the Institute of Geomatics Engineering at the University of Applied Sciences Northwestern Switzerland (FHNW). i3D OpenWebGlobe is a high-performance 3D geovisualisation engine supporting the web-based streaming of very large amounts of terrain and POI data.

SuperDARN elevation angle calibration using HAARP-induced backscatter

NASA Astrophysics Data System (ADS)

Shepherd, S. G.; Thomas, E. G.; Palinski, T. J.; Bristow, W.

2017-12-01

SuperDARN radars rely on refraction in the ionosphere to make Doppler measurements of backscatter from ionospheric irregularities or the ground/sea, often to ranges of 4000 km or more. Elevation angle measurements of backscattered signals can be important for proper geolocation, mode identification and Doppler velocity corrections to the data. SuperDARN radars are equipped with a secondary array to make elevation angle measurements, however, calibration is often difficult. One method of calibration is presented here, whereby backscatter from HAARP-induced irregularities, at a known location, is used to independently determine the elevation angle of signals. Comparisons are made for several radars with HAARP in their field-of-view in addition to the results obtained fromray-tracing in a model ionosphere.

Calculation of the effects of ice on the backscatter of a ground plane

NASA Technical Reports Server (NTRS)

Lambert, K. M.; Peters, L., Jr.

1988-01-01

Described is a technique for examining the effect of a rough ice layer on the backscatter of a ground plane. The technique is applied to the special case of a rough ice layer that is periodic in space. By assuming that the roughness is periodic, the backscatter of the ground plane can be found from the backscatter of a single period. Backscatter calculations are presented for a single period in which the thickness of the ice layer has a Gaussian shape.

Using Digital Globes to Explore the Deep Sea and Advance Public Literacy in Earth System Science

ERIC Educational Resources Information Center

Beaulieu, Stace E.; Emery, Emery; Brickley, Annette; Spargo, Abbey; Patterson, Kathleen; Joyce, Katherine; Silva, Tim; Madin, Katherine

2015-01-01

Digital globes are new technologies increasingly used in informal and formal education to display global datasets and show connections among Earth systems. But how effective are digital globes in advancing public literacy in Earth system science? We addressed this question by developing new content for digital globes with the intent to educate and…

Monitoring evolution of HIFU-induced lesions with backscattered ultrasound

NASA Astrophysics Data System (ADS)

Anand, Ajay; Kaczkowski, Peter J.

2003-04-01

Backscattered radio frequency (rf) data from a modified commercial ultrasound scanner were collected in a series of in vitro experiments in which high intensity focused ultrasound (HIFU) was used to create lesions in freshly excised bovine liver tissue. Two signal processing approaches were used to visualize the temporal evolution of lesion formation. First, apparent tissue motion due to temperature rise was detected using cross-correlation techniques. Results indicate that differential processing of travel time can provide temperature change information throughout the therapy delivery phase and after HIFU has been turned off, over a relatively large spatial region. Second, changes in the frequency spectrum of rf echoes due to changes in the scattering properties of the heated region were observed well before the appearance of hyper-echogenic spots in the focal zone. Furthermore, the increase in attenuation in the lesion zone changes the measured backscatter spectrum from regions distal to it along the imaging beam. Both effects were visualized using spectral processing and display techniques that provide a color spatial map of these features for the clinician. Our results demonstrate potential for these ultrasound-based techniques in targeting and monitoring of HIFU therapy, and perhaps post-treatment visualization of HIFU-induced lesions.

Replacing backscattering with reduced scattering. A better formulation of reflectance function?

NASA Astrophysics Data System (ADS)

Piskozub, Jacek; McKee, David; Freda, Wlodzimierz

2014-05-01

Modern reflectance formulas all involve backscattering coefficient divided by absorption coefficient (bb/a). The backscattering (or backward scattering) coefficient describes how much of the incident radiation is scattered at angles between 90 and 180 deg. However, water leaving photons are not necessarily backscattered because it is possible for a variable fraction to exit after multiple forward scattering events. Therefore the whole angular function of scattering probability (phase function) influences the reflectance signal. This is the reason why phase functions of identical backscattering ratio may result in different reflectance values, contrary to the universally used formula. This creates the question whether there may exist a better formula using a parameter better describing phase function shape than backscattering ratio. The asymmetry parameter g (the average scattering cosine) is commonly used to parametrize phase functions. A replacement for backscattering should decrease with increasing g. Therefore, the simplest candidate to replace backscattering has the form of b(1-g), where b is the scattering coefficient. Such a parameter is well known in biomedical optics under the name of reduced scattering (sometimes transport scattering). It has even been used in parametrizing reflectance in (highly turbid) human tissues. However no attempt has been made to check its usefulness in marine optics. We perform Monte Carlo radiative transfer calculations of reflectance for multiple combinations of inherent optical properties, including different phase functions. The results are used to create a new reflectance formula as a function of reduced scattering and absorption and test its robustness to changes in phase function shape compared to the traditional bb/a formula. We discuss its usefulness as well as advantages and disadvantages compared to the traditional formulation.

DigitalGlobe(TM) Incorporated Corporate and System Update

NASA Technical Reports Server (NTRS)

Thomassie, Brett

2007-01-01

This viewgraph presentation describes a system update of Quickbird, the world's highest resolution commercial imaging satellite, operated by DigitalGlobe (TM) Incorporated. A satellite comparison of Quickbird, WorldView-60, and WorldView-110 is also presented.

A laboratory investigation into microwave backscattering from sea ice. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Bredow, Jonathan W.

1989-01-01

The sources of scattering of artificial sea ice were determined, backscatter measurements semi-quantitatively were compared with theoretical predictions, and inexpensive polarimetric radars were developed for sea ice backscatter studies. A brief review of the dielectric properties of sea ice and of commonly used surface and volume scattering theories is presented. A description is provided of the backscatter measurements performed and experimental techniques used. The development of inexpensive short-range polarimetric radars is discussed. The steps taken to add polarimetric capability to a simple FM-W radar are considered as are sample polarimetric phase measurements of the radar. Ice surface characterization data and techniques are discussed, including computation of surface rms height and correlation length and air bubble distribution statistics. A method is also presented of estimating the standard deviation of rms height and correlation length for cases of few data points. Comparisons were made of backscatter measurements and theory. It was determined that backscatter from an extremely smooth saline ice surface at C band cannot be attributed only to surface scatter. It was found that snow cover had a significant influence on backscatter from extremely smooth saline ice at C band.

The SIR-B observations of microwave backscatter dependence on soil moisture, surface roughness, and vegetation covers

NASA Technical Reports Server (NTRS)

Wang, J. R.; Shiue, J. C.; Engman, E. T.; Rusek, M.; Steinmeier, C.

1986-01-01

An experiment was conducted from an L-band SAR aboard Space Shuttle Challenger in October 1984 to study the microwave backscatter dependence on soil moisture, surface roughness, and vegetation cover. The results based on the analyses of an image obtained at 21-deg incidence angle show a positive correlatlion between scattering coefficient and soil moisture content, with a sensitivity comparable to that derived from the ground radar measurements reported by Ulaby et al. (1978). The surface roughness strongly affects the microwave backscatter. A factor of two change in the standard deviation of surface roughness height gives a corresponding change of about 8 dB in the scattering coefficient. The microwave backscatter also depends on the vegetation types. Under the dry soil conditions, the scattering coefficient is observed to change from about -24 dB for an alfalfa or lettuce field to about -17 dB for a mature corn field. These results suggest that observations with a SAR system of multiple frequencies and polarizations are required to unravel the effects of soil moisture, surface roughness, and vegetation cover.

On diel variability of marine sediment backscattering properties caused by microphytobenthos photosynthesis: Impact of environmental factors

NASA Astrophysics Data System (ADS)

Gorska, Natalia; Kowalska-Duda, Ewa; Pniewski, Filip; Latała, Adam

2018-06-01

The study has been motivated by the development of the hydroacoustic techniques for mapping and classifying the benthic habitats and for the research of the microbenthos photosynthesis in the semi-enclosed Baltic Sea, particularly sensitive to human activity. The investigation of the effect of the benthic microalgal photosynthesis on the echo signal from the Baltic sandy sediments is continuing. The study clarifies the impact of the abiotic and biotic factors on the diel variation of the backscattering caused by the benthic microalgal photosynthetic activity. Five multiday laboratory experiments, different in hydrophysical or biological conditions, were conducted. During each measurement series, the "day" (illumination) and "night" (darkness) conditions (L:D cycle) were simulated and the diel variations of the echo energy of the backscattered signal were analyzed. The hydroacoustic data were acquired along with measuring biological and biooptical parameters and oxygen concentration. The study demonstrated the impact of microphytobenthos photosynthesis on the backscattering properties of the marine sediment which is sensitive to the illumination level, benthic microalgal biomass and macrozoobenthos bioturbation.

A desktop system of virtual morphometric globes for Mars and the Moon

NASA Astrophysics Data System (ADS)

Florinsky, I. V.; Filippov, S. V.

2017-03-01

Global morphometric models can be useful for earth and planetary studies. Virtual globes - programs implementing interactive three-dimensional (3D) models of planets - are increasingly used in geo- and planetary sciences. We describe the development of a desktop system of virtual morphometric globes for Mars and the Moon. As the initial data, we used 15'-gridded global digital elevation models (DEMs) extracted from the Mars Orbiter Laser Altimeter (MOLA) and the Lunar Orbiter Laser Altimeter (LOLA) gridded archives. For two celestial bodies, we derived global digital models of several morphometric attributes, such as horizontal curvature, vertical curvature, minimal curvature, maximal curvature, and catchment area. To develop the system, we used Blender, the free open-source software for 3D modeling and visualization. First, a 3D sphere model was generated. Second, the global morphometric maps were imposed to the sphere surface as textures. Finally, the real-time 3D graphics Blender engine was used to implement rotation and zooming of the globes. The testing of the developed system demonstrated its good performance. Morphometric globes clearly represent peculiarities of planetary topography, according to the physical and mathematical sense of a particular morphometric variable.

A web system of virtual morphometric globes for Mars and the Moon

NASA Astrophysics Data System (ADS)

Florinsky, I. V.; Garov, A. S.; Karachevtseva, I. P.

2018-09-01

We developed a web system of virtual morphometric globes for Mars and the Moon. As the initial data, we used 15-arc-minutes gridded global digital elevation models (DEMs) extracted from the Mars Orbiter Laser Altimeter (MOLA) and the Lunar Orbiter Laser Altimeter (LOLA) gridded archives. We derived global digital models of sixteen morphometric variables including horizontal, vertical, minimal, and maximal curvatures, as well as catchment area and topographic index. The morphometric models were integrated into the web system developed as a distributed application consisting of a client front-end and a server back-end. The following main functions are implemented in the system: (1) selection of a morphometric variable; (2) two-dimensional visualization of a calculated global morphometric model; (3) 3D visualization of a calculated global morphometric model on the sphere surface; (4) change of a globe scale; and (5) globe rotation by an arbitrary angle. Free, real-time web access to the system is provided. The web system of virtual morphometric globes can be used for geological and geomorphological studies of Mars and the Moon at the global, continental, and regional scales.

Adaptive focus for deep tissue using diffuse backscatter

NASA Astrophysics Data System (ADS)

Kress, Jeremy; Pourrezaei, Kambiz

2014-02-01

A system integrating high density diffuse optical imaging with adaptive optics using MEMS for deep tissue interaction is presented. In this system, a laser source is scanned over a high density fiber bundle using Digital Micromirror Device (DMD) and channeled to a tissue phantom. Backscatter is then collected from the tissue phantom by a high density fiber array of different fiber type and channeled to CMOS sensor for image acquisition. Intensity focus is directly verified using a second CMOS sensor which measures intensity transmitted though the tissue phantom. A set of training patterns are displayed on the DMD and backscatter is numerically fit to the transmission intensity. After the training patterns are displayed, adaptive focus is performed using only the backscatter and fitting functions. Additionally, tissue reconstruction and prediction of interference focusing by photoacoustic and optical tomographic methods is discussed. Finally, potential NIR applications such as in-vivo adaptive neural photostimulation and cancer targeting are discussed.

Backscatter and attenuation properties of mammalian brain tissues

NASA Astrophysics Data System (ADS)

Wijekularatne, Pushpani Vihara

Traumatic Brain Injury (TBI) is a common category of brain injuries, which contributes to a substantial number of deaths and permanent disability all over the world. Ultrasound technology plays a major role in tissue characterization due to its low cost and portability that could be used to bridge a wide gap in the TBI diagnostic process. This research addresses the ultrasonic properties of mammalian brain tissues focusing on backscatter and attenuation. Orientation dependence and spatial averaging of data were analyzed using the same method resulting from insertion of tissue sample between a transducer and a reference reflector. Apparent backscatter transfer function (ABTF) at 1 to 10 MHz, attenuation coefficient and backscatter coefficient (BSC) at 1 to 5 MHz frequency ranges were measured on ovine brain tissue samples. The resulting ABTF was a monotonically decreasing function of frequency and the attenuation coefficient and BSC generally were increasing functions of frequency, results consistent with other soft tissues such as liver, blood and heart.

Voss with globe in Service module

NASA Image and Video Library

2001-04-08

ISS002-E-5136 (8 April 2001) --- Astronaut James S. Voss, Expedition Two flight engineer, holds a globe to be used for assistance in Earth observation duties. Voss is in the Zvezda Service Module aboard the International Space Station (ISS), where's he been working for several weeks along with cosmonaut Yury V. Usachev of Rosaviakosmos and astronaut Susan J. Helms. The image was recorded with a digital still camera.

Earth Adventure: Virtual Globe-based Suborbital Atmospheric Greenhouse Gases Exploration

NASA Astrophysics Data System (ADS)

Wei, Y.; Landolt, K.; Boyer, A.; Santhana Vannan, S. K.; Wei, Z.; Wang, E.

2016-12-01

The Earth Venture Suborbital (EVS) mission is an important component of NASA's Earth System Science Pathfinder program that aims at making substantial advances in Earth system science through measurements from suborbital platforms and modeling researches. For example, the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) project of EVS-1 collected measurements of greenhouse gases (GHG) on local to regional scales in the Alaskan Arctic. The Atmospheric Carbon and Transport - America (ACT-America) project of EVS-2 will provide advanced, high-resolution measurements of atmospheric profiles and horizontal gradients of CO2 and CH4.As the long-term archival center for CARVE and the future ACT-America data, the Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) has been developing a versatile data management system for CARVE data to maximize their usability. One of these efforts is the virtual globe-based Suborbital Atmospheric GHG Exploration application. It leverages Google Earth to simulate the 185 flights flew by the C-23 Sherpa aircraft in 2012-2015 for the CARVE project. Based on Google Earth's 3D modeling capability and the precise coordinates, altitude, pitch, roll, and heading info of the aircraft recorded in every second during each flight, the application provides users accurate and vivid simulation of flight experiences, with an active 3D visualization of a C-23 Sherpa aircraft in view. This application provides dynamic visualization of GHG, including CO2, CO, H2O, and CH4 captured during the flights, at the same pace of the flight simulation in Google Earth. Photos taken during those flights are also properly displayed along the flight paths. In the future, this application will be extended to incorporate more complicated GHG measurements (e.g. vertical profiles) from the ACT-America project. This application leverages virtual globe technology to provide users an integrated framework to interactively explore information

Backscatter Correction Algorithm for TBI Treatment Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez-Nieto, B.; Sanchez-Doblado, F.; Arrans, R.

2015-01-15

The accuracy requirements in target dose delivery is, according to ICRU, ±5%. This is so not only in standard radiotherapy but also in total body irradiation (TBI). Physical dosimetry plays an important role in achieving this recommended level. The semi-infinite phantoms, customarily used for dosimetry purposes, give scatter conditions different to those of the finite thickness of the patient. So dose calculated in patient’s points close to beam exit surface may be overestimated. It is then necessary to quantify the backscatter factor in order to decrease the uncertainty in this dose calculation. The backward scatter has been well studied atmore » standard distances. The present work intends to evaluate the backscatter phenomenon under our particular TBI treatment conditions. As a consequence of this study, a semi-empirical expression has been derived to calculate (within 0.3% uncertainty) the backscatter factor. This factor depends lineally on the depth and exponentially on the underlying tissue. Differences found in the qualitative behavior with respect to standard distances are due to scatter in the bunker wall close to the measurement point.« less

Growth and field emission properties of globe-like diamond microcrystalline-aggregate

NASA Astrophysics Data System (ADS)

Gao, Jin-hai; Zhang, Lan; Zhao, Limin; Hao, Haoshan

2009-02-01

The globe-like diamond microcrystalline-aggregates were fabricated by microwave plasma chemical vapor deposition (MPCVD) method. The ceramic with a Ti mental layer was used as substrate. The fabricated diamond was evaluated by Raman scattering spectroscopy, X-ray diffraction spectrum (XRD), and scanning electron microscope (SEM). The field emission properties were tested by using a diode structure in a vacuum. A phosphor-coated indium tin oxide (ITO) anode was used for observing and characterizing the field emission. It was found that the globe-like diamond microcrystalline-aggregates exhibited good electron emission properties. The turn-on field was only 0.55 V/μm, and emission current density as high as 11 mA/cm 2 was obtained under an applied field of 2.9 V/μm for the first operation. The growth mechanism and field emission properties of the globe-like diamond microcrystalline-aggregates are discussed relating to microstructure and electrical conductivity.

Creating Successful Scientist-Teacher-Student Collaborations: Examples From the GLOBE Program

NASA Astrophysics Data System (ADS)

Geary, E.; Wright, E.; Yule, S.; Randolph, G.; Larsen, J.; Smith, D.

2007-12-01

Actively engaging students in research on the environment at local, regional, and globe scales is a primary objective of the GLOBE (Global Learning and Observations to Benefit the Environment) Program. During the past 18 months, GLOBE, an international education and science program in 109 countries and tens of thousands of schools worldwide, has been working with four NSF-funded Earth System Science Projects to involve K-12 students, teachers, and scientists in collaborative research investigations of Seasons and Biomes, the Carbon Cycle, Local and Extreme Environments, and Watersheds. This talk will discuss progress to date in each of these investigation areas and highlight successes and challenges in creating effective partnerships between diverse scientific and educational stakeholders. More specifically we will discuss lessons learned in the following areas: (a) mutual goal and responsibility setting, (b) resource allocation, (c) development of adaptable learning activities, tools, and services, (d) creation of scientist and school networks, and (e) development of evaluation metrics, all in support of student research.

Observations of El Niño impacts using in situ GLOBE protocols and satellite data

NASA Astrophysics Data System (ADS)

Srinivasan, M. M.; Destaerke, D.

2015-12-01

The El Niño phenomenon is a periodic ocean condition that occurs every two to ten years in the central and east-central equatorial Pacific Ocean. It alters the normal patterns of ocean circulation, surface temperature, and evaporation, causing noticeable and often severe changes in weather conditions in many areas of the world. El Niño is the warm phase of the El Niño Southern Oscillation (ENSO), and usually reaches its peak between December and February time period. El Niño and its worldwide consequences are studied by the school network of the GLOBE Program (www.globe.gov) which brings together students, teachers, and scientists in support of student research and validation of international Earth science research projects. Since the start of the GLOBE Program over 20 years ago, GLOBE classrooms utilize carefully developed daily, weekly, or seasonally protocols such as maximum, minimum and current temperatures, rainfall, soil moisture, and others, to measure changes in the environment. The data collected by the students is entered in an online GLOBE database. In addition to the student-contributed data, automated stations also collect and send measurements to the GLOBE database.Students compare their data with global data acquired by satellites to help validate the satellite data. With a potentially historic-level El Niño event thought to be on the horizon--possibly one of the strongest in 50 years—we will propose an emphasis on measurements from GLOBE schools that will support studies and satellite observations of El Niño. We plan to provide the schools with additional satellite data sets such as ocean temperature measurements from Advanced Very High Resolution Radiometer (AVHRR), sea surface elevation measurements from Jason-2 and 3 (after it launches), and others to be identified. We wish to address and support the following educational objectives: - Demonstrate how El Niño affects local precipitation and temperature across the globe, - Link teachers

Modelling of backscatter from vegetation layers

NASA Technical Reports Server (NTRS)

Van Zyl, J. J.; Engheta, N.; Papas, C. H.; Elachi, C.; Zebker, H.

1985-01-01

A simple way to build up a library of models which may be used to distinguish between the different types of vegetation and ground surfaces by means of their backscatter properties is presented. The curve of constant power received by the antenna (Gamma sphere) is calculated for the given Stokes Scattering Operator, and model parameters are adopted of the most similar library model Gamma sphere. Results calculated for a single scattering model resembling coniferous trees are compared with the Gamma spheres of a model resembling tropical region trees. The polarization which would minimize the effect of either the ground surface or the vegetation layer can be calculated and used to analyze the backscatter from the ground surface/vegetation layer combination, and enhance the power received from the desired part of the combination.

Compositional Signatures in Acoustic Backscatter Over Vegetated and Unvegetated Mixed Sand-Gravel Riverbeds

NASA Astrophysics Data System (ADS)

Buscombe, D.; Grams, P. E.; Kaplinski, M. A.

2017-10-01

Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

Compositional signatures in acoustic backscatter over vegetated and unvegetated mixed sand-gravel riverbeds

USGS Publications Warehouse

Buscombe, Daniel; Grams, Paul E.; Kaplinski, Matt A.

2017-01-01

Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

Globe rupture with post cataract-surgery safety sunglasses.

PubMed

Brooks, Clifford W; Howard, Robert C; Lyons, Robert A; Reilly, Charles D

2010-07-01

We report a case of globe rupture associated with the use of post cataract-surgery protective eyewear. The patient had routine cataract surgery 3 months before presentation and had adapted his post cataract-surgery glasses to use on the tennis court. He experienced a large posterior globe rupture after falling directly onto his face during a match. Spectacle torsion is the suspected biomechanical process that led to the rupture. We conclude that although the glasses given to many patients after cataract surgery are protective for most low-impact injuries, patients should be aware they are not designed for activities with a risk for significant impact. Patients should also be counseled to use protective eyewear specifically designed and approved for the sport or activity in which they participate. No author has a financial or proprietary interest in any material or method mentioned. Published by Elsevier Inc.

Enhanced backscatter of optical beams reflected in turbulent air.

PubMed

Nelson, W; Palastro, J P; Wu, C; Davis, C C

2015-07-01

Optical beams propagating through air acquire phase distortions from turbulent fluctuations in the refractive index. While these distortions are usually deleterious to propagation, beams reflected in a turbulent medium can undergo a local recovery of spatial coherence and intensity enhancement referred to as enhanced backscatter (EBS). Here we validate the commonly used phase screen simulation with experimental results obtained from lab-scale experiments. We also verify theoretical predictions of the dependence of the turbulence strength on EBS. Finally, we present a novel algorithm called the "tilt-shift method" which allows detection of EBS in frozen turbulence, reducing the time required to detect the EBS signal.

The Cause of the Hot Spot in Vegetation Canopies and Soils: Shadow-Hiding Versus Coherent Backscatter

NASA Technical Reports Server (NTRS)

Hapke, Bruce; DiMucci, Dominick; Nelson, Robert; Smythe, William

1996-01-01

Two different mechanisms, shadow-hiding and coherent backscatter, can cause a hot spot, or opposition effect, in the bidirectional reflectance of vegetation and soils. Because the two mechanisms sample different properties, it is important to know which one is primarily responsible in a given medium. This question can be answered by measuring the bidirectional reflectance in circularly polarized light. If the results of the limited experiments reported here can be extrapolated to a wider range of materials, it appears that the primary cause of the hot spot in most vegetation canopies and in moist, clumpy soils is shadow-hiding. However, in vegetation with large numbers of wavelength-sized structures, such as mosses, and in dry, fine-grained soils, the hot spot is dominated by coherent backscatter.

Expansion of effective wet bulb globe temperature for vapor impermeable protective clothing.

PubMed

Sakoi, Tomonori; Mochida, Tohru; Kurazumi, Yoshihito; Sawada, Shin-Ichi; Horiba, Yosuke; Kuwabara, Kohei

2018-01-01

The wet bulb globe temperature (WBGT) is an effective measure for risk screening to prevent heat dISOrders. However, a heat risk evaluation by WBGT requires adjustments depending on the clothing. In this study, we proposed a new effective WBGT (WBGT eff * ) for general vapor permeable clothing ensembles and vapor impermeable protective clothing that is applicable to occupants engaged in moderate intensity work with a metabolic heat production value of around 174W/m 2 . WBGT eff * enables the conversion of heat stress into the scale experienced by the occupant dressed in the basic clothing ensemble (work clothes) based on the heat balances for a human body. We confirmed that WBGT eff * was effective for expressing the critical thermal environments for the prescriptive zones for occupants wearing vapor impermeable protective clothing. Based on WBGT eff * , we succeeded in clarifying how the weights for natural wet bulb, globe, and air temperatures and the intercept changed depending on clothing properties and the surrounding environmental factors when heat stress is expressed by the weighted sum of natural wet bulb, globe, and air temperatures and the intercept. The weight of environmental temperatures (globe and air temperatures) for WBGT eff * for vapor impermeable protective clothing increased compared with that for general vapor permeable clothing, whereas that of the natural wet bulb temperature decreased. For WBGT eff * in outdoor conditions with a solar load, the weighting ratio of globe temperature increased and that of air temperature decreased with air velocity. Approximation equations of WBGT eff * were proposed for both general vapor permeable clothing ensembles and for vapor impermeable protective clothing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anisotropic physical properties of myocardium characterized by ultrasonic measurements of backscatter, attenuation, and velocity

NASA Astrophysics Data System (ADS)

Baldwin, Steven L.

The goal of elucidating the physical mechanisms underlying the propagation of ultrasonic waves in anisotropic soft tissue such as myocardium has posed an interesting and largely unsolved problem in the field of physics for the past 30 years. In part because of the vast complexity of the system being studied, progress towards understanding and modeling the mechanisms that underlie observed acoustic parameters may first require the guidance of careful experiment. Knowledge of the causes of observed ultrasonic properties in soft tissue including attenuation, speed of sound, and backscatter, and how those properties are altered with specific pathophysiologies, may lead to new noninvasive approaches to the diagnosis of disease. The primary aim of this Dissertation is to contribute to an understanding of the physics that underlies the mechanisms responsible for the observed interaction of ultrasound with myocardium. To this end, through-transmission and backscatter measurements were performed by varying acoustic properties as a function of angle of insonification relative to the predominant myofiber direction and by altering the material properties of myocardium by increased protein cross-linking induced by chemical fixation as an extreme form of changes that may occur in certain pathologies such as diabetes. Techniques to estimate acoustic parameters from backscatter were broadened and challenges to implementing these techniques in vivo were addressed. Provided that specific challenges identified in this Dissertation can be overcome, techniques to estimate attenuation from ultrasonic backscatter show promise as a means to investigate the physical interaction of ultrasound with anisotropic biological media in vivo. This Dissertation represents a step towards understanding the physics of the interaction of ultrasonic waves with anisotropic biological media.

Modeling and visualizing borehole information on virtual globes using KML

NASA Astrophysics Data System (ADS)

Zhu, Liang-feng; Wang, Xi-feng; Zhang, Bing

2014-01-01

Advances in virtual globes and Keyhole Markup Language (KML) are providing the Earth scientists with the universal platforms to manage, visualize, integrate and disseminate geospatial information. In order to use KML to represent and disseminate subsurface geological information on virtual globes, we present an automatic method for modeling and visualizing a large volume of borehole information. Based on a standard form of borehole database, the method first creates a variety of borehole models with different levels of detail (LODs), including point placemarks representing drilling locations, scatter dots representing contacts and tube models representing strata. Subsequently, the level-of-detail based (LOD-based) multi-scale representation is constructed to enhance the efficiency of visualizing large numbers of boreholes. Finally, the modeling result can be loaded into a virtual globe application for 3D visualization. An implementation program, termed Borehole2KML, is developed to automatically convert borehole data into KML documents. A case study of using Borehole2KML to create borehole models in Shanghai shows that the modeling method is applicable to visualize, integrate and disseminate borehole information on the Internet. The method we have developed has potential use in societal service of geological information.

An improved Monte-Carlo model of the Varian EPID separating support arm and rear-housing backscatter

NASA Astrophysics Data System (ADS)

Monville, M. E.; Kuncic, Z.; Greer, P. B.

2014-03-01

Previous investigators of EPID dosimetric properties have ascribed the backscatter, that contaminates dosimetric EPID images, to its supporting arm. Accordingly, Monte-Carlo (MC) EPID models have approximated the backscatter signal from the layers under the detector and the robotic support arm using either uniform or non-uniform solid water slabs, or through convolutions with back-scatter kernels. The aim of this work is to improve the existent MC models by measuring and modelling the separate backscatter contributions of the robotic arm and the rear plastic housing of the EPID. The EPID plastic housing is non-uniform with a 11.9 cm wide indented section that runs across the cross-plane direction in the superior half of the EPID which is 1.75 cm closer to the EPID sensitive layer than the rest of the housing. The thickness of the plastic housing is 0.5 cm. Experiments were performed with and without the housing present by removing all components of the EPID from the housing. The robotic support arm was not present for these measurements. A MC model of the linear accelerator and the EPID was modified to include the rear-housing indentation and results compared to the measurement. The rear housing was found to contribute a maximum of 3% additional signal. The rear housing contribution to the image is non-uniform in the in-plane direction with 2% asymmetry across the central 20 cm of an image irradiating the entire detector. The MC model was able to reproduce this non-uniform contribution. The EPID rear housing contributes a non-uniform backscatter component to the EPID image, which has not been previously characterized. This has been incorporated into an improved MC model of the EPID.

Experimental results on the enhanced backscatter phenomenon and its dynamics

NASA Astrophysics Data System (ADS)

Wu, Chensheng; Nelson, William; Ko, Jonathan; Davis, Christopher C.

2014-10-01

Enhanced backscatter effects have long been predicted theoretically and experimentally demonstrated. The reciprocity of a turbulent channel generates a group of paired rays with identical trajectory and phase information that leads to a region in phase space with double intensity and scintillation index. Though simulation work based on phase screen models has demonstrated the existence of the phenomenon, few experimental results have been published describing its characteristics, and possible applications of the enhanced backscatter phenomenon are still unclear. With the development of commercially available high powered lasers and advanced cameras with high frame rates, we have successfully captured the enhanced backscatter effects from different reflection surfaces. In addition to static observations, we have also tilted and pre-distorted the transmitted beam at various frequencies to track the dynamic properties of the enhanced backscatter phenomenon to verify its possible application in guidance and beam and image correction through atmospheric turbulence. In this paper, experimental results will be described, and discussions on the principle and applications of the phenomenon will be included. Enhanced backscatter effects are best observed in certain levels of turbulence (Cn 2≍10-13 m-2/3), and show significant potential for providing self-guidance in beam correction that doesn't introduce additional costs (unlike providing a beacon laser). Possible applications of this phenomenon include tracking fast moving object with lasers, long distance (>1km) alignment, and focusing a high-power corrected laser beam over long distances.

Globe Watch. Teachers' Guide for Globe Watch IV: Mexico, Canada, Finland, Japan, the Arms Race, the Iran-Iraq War.

ERIC Educational Resources Information Center

Turner, Ginny

To enhance the use of the Globe Watch IV public television series, produced jointly by Hampden-Sydney College (Virginia) and the University of North Carolina Center for Public Television, each lesson in this guide provides: (1) a statement of the objective of the program; (2) a synopsis of the issue discussed; (3) background information; (4) brief…

Backscattering enhancement with a finite beam width for millimeter-wavelength weather radars

NASA Astrophysics Data System (ADS)

Kobayashi, Satoru; Tanelli, Simone; Iguchi, Toshio; Im, Eastwood

2004-12-01

Backscattering enhancement from random hydrometeors should increase as wavelengths of radars reach millimeter regions. For 95 GHz radars, the reflectivity of backscattering is expected to increase by 2 dB, due to multiple scattering including backscattering enhancement, for water droplets of diameter of 1 mm with a density of 5 x 103 m-3. Previous theoretical studies of backscattering enhancement considered infinitely extending plane waves. In this paper, we expand the theory to spherical waves with a Gaussian antenna pattern, including depolarizing effects. While the differences from the plane wave results are not great when the optical thickness is small, as the latter increases the differences become significant, and essentially depend on the ratio of radar footprint radius to the mean free path of hydrometeors. In this regime, for a radar footprint that is smaller than the mean free path, the backscattering-enhancement reflectivity corresponding to spherical waves is significantly less pronounced than in the case of the plane wave theory. Hence this reduction factor must be taken into account when analyzing radar reflectivity factors for use in remote sensing applications.

Artist concept of Solar Backscatter UV (SBUV) measurement technique on TIROS

NASA Technical Reports Server (NTRS)

1989-01-01

Artist concept titled OZONE MEASUREMENT TECHNIQUE shows how the Solar Backscatter Ultraviolet (UV) 2 (SBUV-2) on the National Oceanic and Atmospheric Administration's (NOAA's) TIROS satellites (NOAA-9 and NOAA-11) works. Ozone is derived from the 'SBUV' instrument from the ratio of the observed backscattered radiance to the solar irradiance in the ultraviolet. This is called the ultraviolet albedo. During STS-34 Shuttle Solar Backscatter Ultraviolet (SSBUV) instruments in Atlantis', Orbiter Vehicle (OV) 104's, payload bay (PLB) will calibrate the instruments onboard the TIROS satellites. SSBUV is managed by Goddard Space Flight Center (GSFC).

Atmospheric aerosol backscatter measurements using a tunable coherent CO2 lidar

NASA Technical Reports Server (NTRS)

Menzies, R. T.; Kavaya, M. J.; Flamant, P. H.; Haner, D. A.

1984-01-01

Measurements of atmospheric aerosol backscatter coefficients, using a coherent CO2 lidar at 9.25- and 10.6-micron wavelengths, are described. Vertical profiles of the volume backscatter coefficient beta have been measured to a 10-km altitude over the Pasadena, CA, region. These measurements indicate a wide range of variability in beta both in and above the local boundary layer. Certain profiles also indicate a significant enhancement in beta at the 9.25-micron wavelength compared with beta at the 10.6-micron wavelength, which possibly indicates a major contribution to the volume backscatter from ammonium sulfate aerosol particles.

Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas

NASA Astrophysics Data System (ADS)

Roche, Marc; Degrendele, Koen; Vrignaud, Christophe; Loyer, Sophie; Le Bas, Tim; Augustin, Jean-Marie; Lurton, Xavier

2018-06-01

The increased use of backscatter measurements in time series for environmental monitoring necessitates the comparability of individual results. With the current lack of pre-calibrated multibeam echosounder systems for absolute backscatter measurement, a pragmatic solution is the use of natural reference areas for ensuring regular assessment of the backscatter measurement repeatability. This method mainly relies on the assumption of a sufficiently stable reference area regarding its backscatter signature. The aptitude of a natural area to provide a stable and uniform backscatter response must be carefully considered and demonstrated by a sufficiently long time-series of measurements. Furthermore, this approach requires a strict control of the acquisition and processing parameters. If all these conditions are met, stability check and relative calibration of a system are possible by comparison with the averaged backscatter values for the area. Based on a common multibeam echosounder and sampling campaign completed by available bathymetric and backscatter time series, the suitability as a backscatter reference area of three different candidates was evaluated. Two among them, Carré Renard and Kwinte, prove to be excellent choices, while the third one, Western Solent, lacks sufficient data over time, but remains a valuable candidate. The case studies and the available backscatter data on these areas prove the applicability of this method. The expansion of the number of commonly used reference areas and the growth of the number of multibeam echosounder controlled thereon could greatly contribute to the further development of quantitative applications based on multibeam echosounder backscatter measurements.

Detecting changes in ultrasound backscattered statistics by using Nakagami parameters: Comparisons of moment-based and maximum likelihood estimators.

PubMed

Lin, Jen-Jen; Cheng, Jung-Yu; Huang, Li-Fei; Lin, Ying-Hsiu; Wan, Yung-Liang; Tsui, Po-Hsiang

2017-05-01

The Nakagami distribution is an approximation useful to the statistics of ultrasound backscattered signals for tissue characterization. Various estimators may affect the Nakagami parameter in the detection of changes in backscattered statistics. In particular, the moment-based estimator (MBE) and maximum likelihood estimator (MLE) are two primary methods used to estimate the Nakagami parameters of ultrasound signals. This study explored the effects of the MBE and different MLE approximations on Nakagami parameter estimations. Ultrasound backscattered signals of different scatterer number densities were generated using a simulation model, and phantom experiments and measurements of human liver tissues were also conducted to acquire real backscattered echoes. Envelope signals were employed to estimate the Nakagami parameters by using the MBE, first- and second-order approximations of MLE (MLE 1 and MLE 2 , respectively), and Greenwood approximation (MLE gw ) for comparisons. The simulation results demonstrated that, compared with the MBE and MLE 1 , the MLE 2 and MLE gw enabled more stable parameter estimations with small sample sizes. Notably, the required data length of the envelope signal was 3.6 times the pulse length. The phantom and tissue measurement results also showed that the Nakagami parameters estimated using the MLE 2 and MLE gw could simultaneously differentiate various scatterer concentrations with lower standard deviations and reliably reflect physical meanings associated with the backscattered statistics. Therefore, the MLE 2 and MLE gw are suggested as estimators for the development of Nakagami-based methodologies for ultrasound tissue characterization. Copyright © 2017 Elsevier B.V. All rights reserved.

External quantum efficiency enhancement by photon recycling with backscatter evasion.

PubMed

Nagano, Koji; Perreca, Antonio; Arai, Koji; Adhikari, Rana X

2018-05-01

The nonunity quantum efficiency (QE) in photodiodes (PD) causes deterioration of signal quality in quantum optical experiments due to photocurrent loss as well as the introduction of vacuum fluctuations into the measurement. In this paper, we report that the external QE enhancement of a PD was demonstrated by recycling the reflected photons. The external QE for an InGaAs PD was increased by 0.01-0.06 from 0.86-0.92 over a wide range of incident angles. Moreover, we confirmed that this technique does not increase backscattered light when the recycled beam is properly misaligned.

Aerosol backscatter lidar calibration and data interpretation

NASA Technical Reports Server (NTRS)

Kavaya, M. J.; Menzies, R. T.

1984-01-01

A treatment of the various factors involved in lidar data acquisition and analysis is presented. This treatment highlights sources of fundamental, systematic, modeling, and calibration errors that may affect the accurate interpretation and calibration of lidar aerosol backscatter data. The discussion primarily pertains to ground based, pulsed CO2 lidars that probe the troposphere and are calibrated using large, hard calibration targets. However, a large part of the analysis is relevant to other types of lidar systems such as lidars operating at other wavelengths; continuous wave (CW) lidars; lidars operating in other regions of the atmosphere; lidars measuring nonaerosol elastic or inelastic backscatter; airborne or Earth-orbiting lidar platforms; and lidars employing combinations of the above characteristics.

A framework to quantify uncertainties of seafloor backscatter from swath mapping echosounders

NASA Astrophysics Data System (ADS)

Malik, Mashkoor; Lurton, Xavier; Mayer, Larry

2018-06-01

Multibeam echosounders (MBES) have become a widely used acoustic remote sensing tool to map and study the seafloor, providing co-located bathymetry and seafloor backscatter. Although the uncertainty associated with MBES-derived bathymetric data has been studied extensively, the question of backscatter uncertainty has been addressed only minimally and hinders the quantitative use of MBES seafloor backscatter. This paper explores approaches to identifying uncertainty sources associated with MBES-derived backscatter measurements. The major sources of uncertainty are catalogued and the magnitudes of their relative contributions to the backscatter uncertainty budget are evaluated. These major uncertainty sources include seafloor insonified area (1-3 dB), absorption coefficient (up to > 6 dB), random fluctuations in echo level (5.5 dB for a Rayleigh distribution), and sonar calibration (device dependent). The magnitudes of these uncertainty sources vary based on how these effects are compensated for during data acquisition and processing. Various cases (no compensation, partial compensation and full compensation) for seafloor insonified area, transmission losses and random fluctuations were modeled to estimate their uncertainties in different scenarios. Uncertainty related to the seafloor insonified area can be reduced significantly by accounting for seafloor slope during backscatter processing while transmission losses can be constrained by collecting full water column absorption coefficient profiles (temperature and salinity profiles). To reduce random fluctuations to below 1 dB, at least 20 samples are recommended to be used while computing mean values. The estimation of uncertainty in backscatter measurements is constrained by the fact that not all instrumental components are characterized and documented sufficiently for commercially available MBES. Further involvement from manufacturers in providing this essential information is critically required.

Polished sample preparing and backscattered electron imaging and of fly ash-cement paste

NASA Astrophysics Data System (ADS)

Feng, Shuxia; Li, Yanqi

2018-03-01

In recent decades, the technology of backscattered electron imaging and image analysis was applied in more and more study of mixed cement paste because of its special advantages. Test accuracy of this technology is affected by polished sample preparation and image acquisition. In our work, effects of two factors in polished sample preparing and backscattered electron imaging were investigated. The results showed that increasing smoothing pressure could improve the flatness of polished surface and then help to eliminate interference of morphology on grey level distribution of backscattered electron images; increasing accelerating voltage was beneficial to increase gray difference among different phases in backscattered electron images.

Ocean Raman Scattering in Satellite Backscatter UV Measurements

NASA Technical Reports Server (NTRS)

Vasilkov, Alexander P.; Joiner, Joanna; Gleason, James; Bhartia, Pawan; Bhartia, P. K. (Technical Monitor)

2002-01-01

Ocean Raman scattering significantly contributes to the filling-in of solar Fraunhofer lines measured by satellite backscatter ultraviolet (buy) instruments in the cloudless atmosphere over clear ocean waters. A model accounting for this effect in buy measurements is developed and compared with observations from the Global Ozone Monitoring Experiment (GONE). The model extends existing models for ocean Raman scattering to the UV spectral range. Ocean Raman scattering radiance is propagated through the atmosphere using a concept of the Lambert equivalent reflectively and an accurate radiative transfer model for Rayleigh scattering. The model and observations can be used to evaluate laboratory measurements of pure water absorption in the UV. The good agreement between model and observations suggests that buy instruments may be useful for estimating chlorophyll content.

Citizen Scientist Contributions to Observations Benefiting the Earth through the GLOBE Program

NASA Astrophysics Data System (ADS)

Chambers, L. H.; Riebeek Kohl, H.; Murphy, A.; Butler, D. M.

2017-12-01

Citizen science has proliferated recently due to widespread use of the internet and mobile devices, but it has a long history (i.e., the Christmas Bird Count). Since the mid-1990s, the GLOBE Program has engaged participants at a global scale. Though initially focused on teachers and students in formal education settings, it quickly attracted interest from the public as well. In 2016, GLOBE formally launched an initiative to widely engage citizen scientists in its 117 countries through release of a mobile app called GLOBE Observer (GO). GO seeks to increase the number and distribution of participants by providing a simple, engaging - and fun - interface to collect and report data. Observations featured in the app are a carefully selected subset of 50+ GLOBE measurement protocols. They must leverage app features, require little to no equipment besides the mobile device, and have scientists or other stakeholders ready to use the data. The app is designed to minimize barriers to participation, but for those who want to do or know more GLOBE also offers on-line training to turn observers into community members with recognized certification in a protocol area. First released was a cloud observation protocol, supporting validation of a variety of Earth imaging sensors. Second was a mosquito habitat mapping protocol, poised to greatly increase the amount and distribution of local data to validate disease forecast models based on remotely sensed conditions, with additional focus on eliminating disease-carrying mosquito breeding sites. Next in development is a land cover protocol to obtain ground truth imagery for the Landsat science team. The app is also being leveraged for quick development of a short-term eclipse mini-app, to be used on August 21st only during the North American eclipse. This app is designed to make it easy for large numbers of people observing the eclipse, throughout North America, to take and record high time resolution observations of cloud cover and

Enhanced backscatter of a reflected beam in atmospheric turbulence

NASA Astrophysics Data System (ADS)

Churnside, James H.; Wilson, James J.

1993-05-01

We measure the mean and the variance of the irradiance of a diverging laser beam after reflection from a retroreflector and from a plane mirror in a turbulent atmosphere. Increases in both the mean irradiance and the normalized variance are observed in the direct backscatter direction because of correlation of turbulence on the outgoing path and the return path. The backscattered irradiance is enhanced by a factor of about 2 and the variance by somewhat less.

Taking the world for a spin: teaching spatial and data visualization with a digital globe

NASA Astrophysics Data System (ADS)

Teplitzky, S.; Powell, S.

2016-12-01

In the summer of 2016, the Earth Sciences & Map Library at the University of California, Berkeley, purchased a Magic Planet digital globe in a collaboration between the library and the departments of Geography and Earth & Planetary Science. This 30" diameter 3D display supplements and expands the library's instruction and outreach activities in GIS, data visualization and modeling. Faculty and graduate students were surveyed regarding their interest in using the globe for teaching and research projects. Based on this feedback, librarians developed a basic training plan for using the globe in the classroom, as well as an assessment tool to rate the effectiveness of instruction with the digital globe. Student and faculty responses at the end of fall semester (2016) will be evaluated for future plans to increase the variety of data sets and animations available to view on the globe. Curriculum and guides for visualizing custom and interactive data sets will be developed and made available based on current researcher and student interests. We are excited about partnering with our departments and engaging our students in the possibilities of 3d visualization, and look forward to sharing lessons learned.

Classification of kidney and liver tissue using ultrasound backscatter data

NASA Astrophysics Data System (ADS)

Aalamifar, Fereshteh; Rivaz, Hassan; Cerrolaza, Juan J.; Jago, James; Safdar, Nabile; Boctor, Emad M.; Linguraru, Marius G.

2015-03-01

Ultrasound (US) tissue characterization provides valuable information for the initialization of automatic segmentation algorithms, and can further provide complementary information for diagnosis of pathologies. US tissue characterization is challenging due to the presence of various types of image artifacts and dependence on the sonographer's skills. One way of overcoming this challenge is by characterizing images based on the distribution of the backscatter data derived from the interaction between US waves and tissue. The goal of this work is to classify liver versus kidney tissue in 3D volumetric US data using the distribution of backscatter US data recovered from end-user displayed Bmode image available in clinical systems. To this end, we first propose the computation of a large set of features based on the homodyned-K distribution of the speckle as well as the correlation coefficients between small patches in 3D images. We then utilize the random forests framework to select the most important features for classification. Experiments on in-vivo 3D US data from nine pediatric patients with hydronephrosis showed an average accuracy of 94% for the classification of liver and kidney tissues showing a good potential of this work to assist in the classification and segmentation of abdominal soft tissue.

Adding Another Dimension to Learning: Application of Real World Globes to Undergraduate Geoscience Teaching

NASA Astrophysics Data System (ADS)

McLeod, C. L.; Kugler, A.

2016-12-01

The Geological Globe of the World (www.realworldglobes.com) promotes hands-on, in-class activities and allows students to engage with a physical 3-D model of Earth's characteristic, planet-forming geological features. The effectiveness of this concept in student learning has been demonstrated by two pilot studies presented as posters by Weeraratne et al. (2011) and Stoddard and Rogers (2013) at previous AGU meetings. The impact of the Geological Globe of the World on undergraduate teaching at Miami University, OH during Fall semester 2016 will be presented. It is anticipated that this teaching tool will have the biggest impact on the teaching of our 100-level lab course, GLG 155L, which engages 900 students per academic year. A Learning Assessment based on the learning objectives of GLG 115L has been written in order to demonstrate and evaluate the role of the Geological Globe in student learning. This Learning Assessment will be issued through www.salgsite.org (SALG: Student Assessment of Learning Gains) and will ask students to assess their own knowledge and understanding of key concepts before and after specific lab exercises which implement the globe. From research discussed in Bamford (2013), it has been demonstrated that "students learning with 3D teaching aids had better ordering of concepts and had enhanced skills in describing their learning, including writing more, saying more and being more likely to use models to demonstrate their (own) learning". It is anticipated that through use of the Geological Globe of the World students will be able to interpret Earth's geological features on a 3-D projection including topography, active volcanism, crustal movements and the location of seismic events. The incorporation of the Geological Globe of the World in undergraduate geoscience teaching in GLG 115L, and other departmental courses, aims to encourage students to make observations and collect data in order to interpret and evaluate relevant geological

Mars Digital Image Mosaic Globe

NASA Technical Reports Server (NTRS)

2000-01-01

The photomosaic that forms the base for this globe was created by merging two global digital image models (DIM's) of Mars-a medium-resolution monochrome mosaic processed to emphasize topographic features and a lower resolution color mosaic emphasizing color and albedo variations.

The medium-resolution (1/256 or roughly 231 m/pixel) monochromatic image model was constructed from about 6,000 images having resolutions of 150-350 m/pixel and oblique illumination (Sun 20 o -45 o above the horizon). Radiometric processing was intended to suppress or remove the effects of albedo variations through the use of a high-pass divide filter, followed by photometric normalization so that the contrast of a given topographic slope would be approximately the same in all images.

The global color mosaic was assembled at 1/64 or roughly 864 m/pixel from about 1,000 red- and green-filter images having 500-1,000 m/pixel resolution. These images were first mosaiced in groups, each taken on a single orbit of the Viking spacecraft. The orbit mosaics were then processed to remove spatially and temporally varying atmospheric haze in the overlap regions. After haze removal, the per-orbit mosaics were photometrically normalized to equalize the contrast of albedo features and mosaiced together with cosmetic seam removal. The medium-resolution DIM was used for geometric control of this color mosaic. A green-filter image was synthesized by weighted averaging of the red- and violet-filter mosaics. Finally, the product seen here was obtained by multiplying each color image by the medium-resolution monochrome image. The color balance selected for images in this map series was designed to be close to natural color for brighter, redder regions, such as Arabia Terra and the Tharsis region, but the data have been stretched so that the relatively dark regions appear darker and less red than they actually are.

The images are presented in a projection that portrays the entire surface of Mars in a

Simulation of double-pass stimulated Raman backscattering

NASA Astrophysics Data System (ADS)

Wu, Z.; Chen, Q.; Morozov, A.; Suckewer, S.

2018-04-01

Experiments on Stimulated Raman Backscattering (SRBS) in plasma have demonstrated significantly higher energy conversion in a double-pass amplifier where the laser pulses go through the plasma twice compared with a single-pass amplifier with double the plasma length of a single pass. In this paper, the improvement in understanding recent experimental results is presented by considering quite in detail the effects of plasma heating on the modeling of SRBS. Our simulation results show that the low efficiency of single-pass amplifiers can be attributed to Landau damping and the frequency shift of Langmuir waves. In double-pass amplifiers, these issues can be avoided, to some degree, because pump-induced heating could be reduced, while the plasma cools down between the passes. Therefore, double-pass amplifiers yield considerably enhanced energy transfer from the pump to the seed, hence the output pulse intensity.

The GLOBE Visualization Project: Using WWW in the Classroom.

ERIC Educational Resources Information Center

de La Beaujardiere, J-F; And Others

1997-01-01

Describes a World Wide Web-based, user-friendly, language-independent graphical user interface providing access to visualizations created for GLOBE (Global Learning and Observations to Benefit the Environment), a multinational program of education and science. (DDR)

Radar backscatter measurements from Arctic sea ice during the fall freeze-up

NASA Technical Reports Server (NTRS)

Beaven, S.; Gogineni, S. P.; Shanableh, M.; Gow, A.; Tucker, W.; Jezek, K.

1993-01-01

Radar backscatter measurements from sea ice during the fall freeze-up were performed by the United States Coast Guard Icebreaker Polar Star as a part of the International Arctic Ocean Expedition (IAOE'91) from Aug. to Sep. 1991. The U.S. portion of the experiment took place on board the Polar Star and was referred to as TRAPOLEX '91 (Transpolar expedition) by some investigators. Before prematurely aborting its mission because of mechanical failure of her port shaft, the Polar Star reached 84 deg 57 min N latitude at 35 deg E longitude. The ship was in the ice (greater than 50 percent coverage) from 14 Aug. until 3 Sep. and was operational for all but 6 days due to two instances of mechanical problems with the port shaft. The second was fatal to the ship's participation in the expedition. During the expedition, radar backscatter was measured at C-band under a variety of conditions. These included measurements from young ice types as well as from multiyear and first-/second-year sea ice during the fall freeze-up. The sea ice types were determined by measurement of the ice properties at several of the stations and by visual inspection on others. Radar backscatter measurements were performed over a large portion of the ship's transit into the Arctic ice pack. These were accompanied by in situ sea ice property characterization by the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) at several stations and, when snow was present, its properties were documented by The Microwave Group, Ottawa River (MWG).

Optical analysis of nanoparticles via enhanced backscattering facilitated by 3-D photonic nanojets

NASA Astrophysics Data System (ADS)

Li, Xu; Chen, Zhigang; Taflove, Allen; Backman, Vadim

2005-01-01

We report the phenomenon of ultra-enhanced backscattering of visible light by nanoparticles facilitated by the 3-D photonic nanojet a sub-diffraction light beam appearing at the shadow side of a plane-waveilluminated dielectric microsphere. Our rigorous numerical simulations show that backscattering intensity of nanoparticles can be enhanced up to eight orders of magnitude when locating in the nanojet. As a result, the enhanced backscattering from a nanoparticle with diameter on the order of 10 nm is well above the background signal generated by the dielectric microsphere itself. We also report that nanojet-enhanced backscattering is extremely sensitive to the size of the nanoparticle, permitting in principle resolving sub-nanometer size differences using visible light. Finally, we show how the position of a nanoparticle could be determined with subdiffractional accuracy by recording the angular distribution of the backscattered light. These properties of photonic nanojets promise to make this phenomenon a useful tool for optically detecting, differentiating, and sorting nanoparticles.

Near-IR extinction and backscatter coefficient measurements in low- and mid-altitude clouds

NASA Technical Reports Server (NTRS)

Sztankay, Z. G.

1986-01-01

Knowledge of the attenuation and backscattering properties of clouds is required to high resolution for several types of optical sensing systems. Such data was obtained in about 15 hours of flights through clouds in the vicinity of Washington, D.C. The flights were mainly through stratocumulus, altocumulus, stratus, and stratus fractus clouds and covered an altitude and temperature range of 300 to 3200 m and -13 to 17 C. Two instruments were flown, each of which measured the backscatter from close range in two range bins to independently determine both the extinction and backscatter coefficients. The extinction and backscatter coefficients can be obtained from the signals in the two channels of each instrument, provided that the aerosol is uniform over the measurement region. When this assumptions holds, the extinction coefficient is derived basically from the ratio of the signal in the two channels; the backscatter coefficient can then be obtained from the signal in either channel.

Integrating Multibeam Backscatter Angular Response, Mosaic and Bathymetry Data for Benthic Habitat Mapping

PubMed Central

Che Hasan, Rozaimi; Ierodiaconou, Daniel; Laurenson, Laurie; Schimel, Alexandre

2014-01-01

Multibeam echosounders (MBES) are increasingly becoming the tool of choice for marine habitat mapping applications. In turn, the rapid expansion of habitat mapping studies has resulted in a need for automated classification techniques to efficiently map benthic habitats, assess confidence in model outputs, and evaluate the importance of variables driving the patterns observed. The benthic habitat characterisation process often involves the analysis of MBES bathymetry, backscatter mosaic or angular response with observation data providing ground truth. However, studies that make use of the full range of MBES outputs within a single classification process are limited. We present an approach that integrates backscatter angular response with MBES bathymetry, backscatter mosaic and their derivatives in a classification process using a Random Forests (RF) machine-learning algorithm to predict the distribution of benthic biological habitats. This approach includes a method of deriving statistical features from backscatter angular response curves created from MBES data collated within homogeneous regions of a backscatter mosaic. Using the RF algorithm we assess the relative importance of each variable in order to optimise the classification process and simplify models applied. The results showed that the inclusion of the angular response features in the classification process improved the accuracy of the final habitat maps from 88.5% to 93.6%. The RF algorithm identified bathymetry and the angular response mean as the two most important predictors. However, the highest classification rates were only obtained after incorporating additional features derived from bathymetry and the backscatter mosaic. The angular response features were found to be more important to the classification process compared to the backscatter mosaic features. This analysis indicates that integrating angular response information with bathymetry and the backscatter mosaic, along with their derivatives

Multi-temporal RADARSAT-1 and ERS backscattering signatures of coastal wetlands in southeastern Louisiana

USGS Publications Warehouse

Kwoun, Oh-Ig; Lu, Z.

2009-01-01

Using multi-temporal European Remote-sensing Satellites (ERS-1/-2) and Canadian Radar Satellite (RADARSAT-1) synthetic aperture radar (SAR) data over the Louisiana coastal zone, we characterize seasonal variations of radar backscat-tering according to vegetation type. Our main findings are as follows. First, ERS-1/-2 and RADARSAT-1 require careful radiometric calibration to perform multi-temporal backscattering analysis for wetland mapping. We use SAR backscattering signals from cities for the relative calibration. Second, using seasonally averaged backscattering coefficients from ERS-1/-2 and RADARSAT-1, we can differentiate most forests (bottomland and swamp forests) and marshes (freshwater, intermediate, brackish, and saline marshes) in coastal wetlands. The student t-test results support the usefulness of season-averaged backscatter data for classification. Third, combining SAR backscattering coefficients and an optical-sensor-based normalized difference vegetation index can provide further insight into vegetation type and enhance the separation between forests and marshes. Our study demonstrates that SAR can provide necessary information to characterize coastal wetlands and monitor their changes.

Effects of alternative cropping systems on globe artichoke qualitative traits.

PubMed

Spanu, Emanuela; Deligios, Paola A; Azara, Emanuela; Delogu, Giovanna; Ledda, Luigi

2018-02-01

Traditionally, globe artichoke cultivation in the Mediterranean basin is based on monoculture and on use of high amounts of nitrogen fertiliser. This raises issues regarding its compatibility with sustainable agriculture. We studied the effect of one typical conventional (CONV) and two alternative cropping systems [globe artichoke in sequence with French bean (NCV1), or in biannual rotation (NCV2) with cauliflower and with a leguminous cover crop in inter-row spaces] on yield, polyphenol and mineral content of globe artichoke heads over two consecutive growing seasons. NCV2 showed statistical differences in terms of fresh product yield with respect to the monoculture systems. In addition, the dihydroxycinnamic acids and dicaffeoylquinic acids of non-conventional samples were one-fold significantly higher than the conventional one. All the samples reported good mineral content, although NCV2 achieved a higher Fe content than conventional throughout the two seasons. After two and three dates of sampling, the CONV samples showed the highest levels of K content. In our study, an acceptable commercial yield and quality of 'Spinoso sardo' were achieved by shifting the common conventional agronomic management to more sustainable ones, by means of an accurate choice of cover crop species and rotations introduced in the systems. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Hydrodynamic influences on acoustical and optical backscatter in a fringing reef environment

NASA Astrophysics Data System (ADS)

Pawlak, Geno; Moline, Mark A.; Terrill, Eric J.; Colin, Patrick L.

2017-01-01

Observations of hydrodynamics along with optical and acoustical water characteristics in a tropical fringing reef environment reveal a distinct signature associated with flow characteristics and tidal conditions. Flow conditions are dominated by tidal forcing with an offshore component from the reef flat during ebb. Measurements span variable wave conditions enabling identification of wave effects on optical and acoustical water properties. High-frequency acoustic backscatter (6 MHz) is strongly correlated with tidal forcing increasing with offshore directed flow and modulated by wave height, indicating dominant hydrodynamic influence. Backscatter at 300 and 1200 kHz is predominantly diurnal suggesting a biological component. Optical backscatter is closely correlated with high-frequency acoustic backscatter across the range of study conditions. Acoustic backscatter frequency dependence is used along with changes in optical properties to interpret particle-size variations. Changes across wave heights suggest shifts in particle-size distributions with increases in relative concentrations of smaller particles for larger wave conditions. Establishing a connection between the physical processes of a fringing tropical reef and the resulting acoustical and optical signals allows for interpretation and forecasting of the remote sensing response of these phenomena over larger scales.

Microwave backscattering from an anisotropic soybean canopy

NASA Technical Reports Server (NTRS)

Lang, R. H.; Saatchi, S.; Levine, D. M.

1986-01-01

Electromagnetic backscattering from a soybean canopy is modeled in the L band region of the spectrum. Mature soybean plants are taken as an ensemble of leaves and stems which are represented by lossy dielectric disks and rods respectively. Field data indicated that leaves and stems are not distributed uniformly in the azimuth coordinate. The plant has a tendency to grow out into the area between the rows. The effects on backscattered radar waves was computed by the distorted Born approximation. Results for look directions along the rows and perpendicular to the rows show that only a modest difference occurs in the L band frequency range. The use of another nonuniform distribution, different from those observed experimentally, results in a significant effect due to vegetation asymmetry.

Assessing Place Location Knowledge Using a Virtual Globe

ERIC Educational Resources Information Center

Zhu, Liangfeng; Pan, Xin; Gao, Gongcheng

2016-01-01

Advances in the Google Earth virtual globe and the concomitant Keyhole Markup Language (KML) are providing educators with a convenient platform to cultivate and assess one's place location knowledge (PLK). This article presents a general framework and associated implementation methods for the online testing of PLK using Google Earth. The proposed…

Performance of low-power RFID tags based on modulated backscattering

NASA Astrophysics Data System (ADS)

Mhanna, Zeinab; Sibille, Alain; Contreras, Richard

2017-02-01

Ultra Wideband (UWB) modulated backscattering (MBS) passive Radio-Frequency IDentification (RFID) systems provide a promising solution to overcome many limitations of current narrowband RFID devices. This work addresses the performance of such systems from the point of view of the radio channel between the readers and the tags. Such systems will likely combine several readers, in order to provide both the detection and localization of tags operating in MBS. Two successive measurements campaigns have been carried out in an indoor reference scenario environment. The first is intended to verify the methods and serves as a way to validate the RFID backscattering measurement setup. The second represents a real use case for RFID application and allows one to quantitatively analyze the path loss of the backscattering propagation channel. xml:lang="fr"

Investigation of phonon coherence and backscattering using silicon nanomeshes

DOE PAGES

Lee, Jaeho; Lee, Woochul; Wehmeyer, Geoff; ...

2017-01-04

Phonons can display both wave-like and particle-like behaviour during thermal transport. While thermal transport in silicon nanomeshes has been previously interpreted by phonon wave effects due to interference with periodic structures, as well as phonon particle effects including backscattering, the dominant mechanism responsible for thermal conductivity reductions below classical predictions still remains unclear. Here we isolate the wave-related coherence effects by comparing periodic and aperiodic nanomeshes, and quantify the backscattering effect by comparing variable-pitch nanomeshes. We measure identical (within 6% uncertainty) thermal conductivities for periodic and aperiodic nanomeshes of the same average pitch, and reduced thermal conductivities for nanomeshes withmore » smaller pitches. Ray tracing simulations support the measurement results. We conclude phonon coherence is unimportant for thermal transport in silicon nanomeshes with periodicities of 100 nm and higher and temperatures above 14 K, and phonon backscattering, as manifested in the classical size effect, is responsible for the thermal conductivity reduction.« less

Measuring Ultrasonic Backscatter in the Presence of Nonlinear Propagation

NASA Astrophysics Data System (ADS)

Stiles, Timothy; Guerrero, Quinton

2011-11-01

A goal of medical ultrasound is the formation of quantitative ultrasound images in which contrast is determined by acoustic or physical properties of tissue rather than relative echo amplitude. Such images could greatly enhance early detection of many diseases, including breast cancer and liver cirrhosis. Accurate determination of the ultrasonic backscatter coefficient from patients remains a difficult task. One reason for this difficulty is the inherent nonlinear propagation of ultrasound at high intensities used for medical imaging. The backscatter coefficient from several tissue-mimicking samples were measured using the planar reflector method. In this method, the power spectrum from a sample is compared to the power spectrum of an optically flat sample of quartz. The results should be independent of incident pressure amplitude. Results demonstrate that backscatter coefficients can vary by more than an order of magnitude when ultrasound pressure varies from 0.1 MPa to 1.5 MPa at 5.0 MHz. A new method that incorporates nonlinear propagation is proposed to explain these discrepancies.

Globe of Natural Hazard - A new assessment tool for risk managers

NASA Astrophysics Data System (ADS)

Siebert, A. C.

2009-04-01

earth, and an extensive location database makes searching easy. The knowledge modules for historical catastrophes, megacities and change processes can be linked with each other and displayed on the maps. Completely new is the integration of the topic of climate change: various depictions of climate effects and projections show in which regions of the world risk situations have to be reckoned with in future. Thanks to its comprehensive information, the globe is an important tool for identifying risk locations worldwide and evaluating them from a geoscientific perspective. Thus, the transparency of insurance portfolios can be increased and legal requirements can be met. Munich Re's multi-discipline Geo Risks team combines a wealth of global experience and contacts. Clients benefit from a first-class natural hazard consultancy service and valuable support for introducing and implementing geographical information technology systems. The team can also provide the knowledge and technology to help clients plan and set up in-house solutions tailored to different classes of business in this innovative field of underwriting. With the new DVD "Globe of Natural Hazards" risk managers, scientists, lecturers and the public have access to Munich Re's natural hazard knowledge. The Globe of Natural Hazards is a natural hazard risk management tool that is easy to use and understand. Earth's exposure to extreme natural hazards will continue to increase. To overcome these challenges the insurance industry will need accurate and competent information.

Tilt angle dependence of backscattering enhancements from organ pipe modes of open water-filled cylinders: Measurements and models

NASA Astrophysics Data System (ADS)

Osterhoudt, Curtis F.; Marston, Philip L.

2003-04-01

A simple target for simulating narrow low-frequency resonances of cylinders is an open metal pipe completely filled with water. We have previously described how the high-Q organ-pipe modes having a pressure node near each end are easily observed in backscattering experiments with small cylinders [C. F. Osterhoudt and P. L. Marston, J. Acoust. Soc. Am. 110, 2773 (2001)]. The resonance occurs because of the strong reflection of internal acoustic waves from the open ends of the pipe [H. Levine and J. Schwinger, Phys. Rev. 73, 383-406 (1948)]. In the present research, the dependence of the backscattering amplitude on the orientation of the cylinder is measured and modeled. The tilt angle dependence is affected by the symmetry of the organ pipe mode. An approximation was also developed for the backscattering amplitude at high Q resonances based on energy conservation, reciprocity, and the optical theorem. While this analysis applies to cylinders suspended in water away from boundaries, the organ-pipe modes studied may be useful for investigating scattering processes for buried or partially buried cylinders. [Research supported in part by ONR.

Standoff detection of hidden objects using backscattered ultra-intense laser-produced x-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuwabara, H.; Mori, Y.; Kitagawa, Y.

2013-08-28

Ultra-intense laser-produced sub-ps X-ray pulses can detect backscattered signals from objects hidden in aluminium containers. Coincident measurements using primary X-rays enable differentiation among acrylic, copper, and lead blocks inside the container. Backscattering reveals the shapes of the objects, while their material composition can be identified from the modification methods of the energy spectra of backscattered X-ray beams. This achievement is an important step toward more effective homeland security.

Visualizing dynamic geosciences phenomena using an octree-based view-dependent LOD strategy within virtual globes

NASA Astrophysics Data System (ADS)

Li, Jing; Wu, Huayi; Yang, Chaowei; Wong, David W.; Xie, Jibo

2011-09-01

Geoscientists build dynamic models to simulate various natural phenomena for a better understanding of our planet. Interactive visualizations of these geoscience models and their outputs through virtual globes on the Internet can help the public understand the dynamic phenomena related to the Earth more intuitively. However, challenges arise when the volume of four-dimensional data (4D), 3D in space plus time, is huge for rendering. Datasets loaded from geographically distributed data servers require synchronization between ingesting and rendering data. Also the visualization capability of display clients varies significantly in such an online visualization environment; some may not have high-end graphic cards. To enhance the efficiency of visualizing dynamic volumetric data in virtual globes, this paper proposes a systematic framework, in which an octree-based multiresolution data structure is implemented to organize time series 3D geospatial data to be used in virtual globe environments. This framework includes a view-dependent continuous level of detail (LOD) strategy formulated as a synchronized part of the virtual globe rendering process. Through the octree-based data retrieval process, the LOD strategy enables the rendering of the 4D simulation at a consistent and acceptable frame rate. To demonstrate the capabilities of this framework, data of a simulated dust storm event are rendered in World Wind, an open source virtual globe. The rendering performances with and without the octree-based LOD strategy are compared. The experimental results show that using the proposed data structure and processing strategy significantly enhances the visualization performance when rendering dynamic geospatial phenomena in virtual globes.

Validation of automated supervised segmentation of multibeam backscatter data from the Chatham Rise, New Zealand

NASA Astrophysics Data System (ADS)

Hillman, Jess I. T.; Lamarche, Geoffroy; Pallentin, Arne; Pecher, Ingo A.; Gorman, Andrew R.; Schneider von Deimling, Jens

2018-06-01

Using automated supervised segmentation of multibeam backscatter data to delineate seafloor substrates is a relatively novel technique. Low-frequency multibeam echosounders (MBES), such as the 12-kHz EM120, present particular difficulties since the signal can penetrate several metres into the seafloor, depending on substrate type. We present a case study illustrating how a non-targeted dataset may be used to derive information from multibeam backscatter data regarding distribution of substrate types. The results allow us to assess limitations associated with low frequency MBES where sub-bottom layering is present, and test the accuracy of automated supervised segmentation performed using SonarScope® software. This is done through comparison of predicted and observed substrate from backscatter facies-derived classes and substrate data, reinforced using quantitative statistical analysis based on a confusion matrix. We use sediment samples, video transects and sub-bottom profiles acquired on the Chatham Rise, east of New Zealand. Inferences on the substrate types are made using the Generic Seafloor Acoustic Backscatter (GSAB) model, and the extents of the backscatter classes are delineated by automated supervised segmentation. Correlating substrate data to backscatter classes revealed that backscatter amplitude may correspond to lithologies up to 4 m below the seafloor. Our results emphasise several issues related to substrate characterisation using backscatter classification, primarily because the GSAB model does not only relate to grain size and roughness properties of substrate, but also accounts for other parameters that influence backscatter. Better understanding these limitations allows us to derive first-order interpretations of sediment properties from automated supervised segmentation.

Extinction-to-Backscatter Ratios of Lofted Aerosol Layers Observed During the First Three Months of CALIPSO Measurements

NASA Technical Reports Server (NTRS)

Omar, Ali H.; Vaughan, Mark A.; Liu, Zhaoyan; Hu, Yongxiang; Reagan, John A.; Winker, David M.

2007-01-01

Case studies from the first three months of the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) measurements of lofted aerosol layers are analyzed using transmittance [Young, 1995] and two-wavelength algorithms [Vaughan et al., 2004] to determine the aerosol extinction-to-backscatter ratios at 532 and 1064 nm. The transmittance method requires clear air below the layer so that the transmittance through the layer can be determined. Suitable scenes are selected from the browse images and clear air below features is identified by low 532 nm backscatter signal and confirmed by low depolarization and color ratios. The transmittance and two-wavelength techniques are applied to a number of lofted layers and the extinction-to-backscatter ratios are compared with values obtained from the CALIPSO aerosol models [Omar et al., 2004]. The results obtained from these studies are used to adjust the aerosol models and develop observations based extinction-to-backscatter ratio look-up tables and phase functions. Values obtained by these techniques are compared to Sa determinations using other independent methods with a goal of developing probability distribution functions of aerosol type-specific extinction to backscatter ratios. In particular, the results are compared to values determined directly by the High Spectral Resolution Lidar (HSRL) during the CALIPSO CloudSat Validation Experiments (CCVEX) and Sa determined by the application of the two-wavelength lidar Constrained Ratio Aerosol Model-fit (CRAM) retrieval approach [Cattrall et al., 2005; Reagan et al., 2004] to the HSRL data. The results are also compared to values derived using the empirical relationship between the multiple-scattering fraction and the linear depolarization ratio by using Monte Carlo simulations of water clouds [Hu et al., 2006].

Assessing the accuracy of globe thermometer method in predicting outdoor mean radiant temperature under Malaysia tropical microclimate

NASA Astrophysics Data System (ADS)

Khrit, N. G.; Alghoul, M. A.; Sopian, K.; Lahimer, A. A.; Elayeb, O. K.

2017-11-01

Assessing outdoor human thermal comfort and urban climate quality require experimental investigation of microclimatic conditions and their variations in open urban spaces. For this, it is essential to provide quantitative information on air temperature, humidity, wind velocity and mean radiant temperature. These parameters can be quantified directly except mean radiant temperature (Tmrt). The most accurate method to quantify Tmrt is integral radiation measurements (3-D shortwave and long-wave) which require using expensive radiometer instruments. To overcome this limitation the well-known globe thermometer method was suggested to calculate Tmrt. The aim of this study was to assess the possibility of using indoor globe thermometer method in predicting outdoor mean radiant temperature under Malaysia tropical microclimate. Globe thermometer method using small and large sizes of black-painted copper globes (50mm, 150mm) were used to estimate Tmrt and compare it with the reference Tmrt estimated by integral radiation method. The results revealed that the globe thermometer method considerably overestimated Tmrt during the middle of the day and slightly underestimated it in the morning and late evening. The difference between the two methods was obvious when the amount of incoming solar radiation was high. The results also showed that the effect of globe size on the estimated Tmrt is mostly small. Though, the estimated Tmrt by the small globe showed a relatively large amount of scattering caused by rapid changes in radiation and wind speed.

International Perspectives on the First-Year Experience in Higher Education. The First-Year Experience Monograph Series No. 52

ERIC Educational Resources Information Center

Nutt, Diane, Ed.; Calderon, Denis, Ed.

2009-01-01

Students around the globe have unique first-year experiences but struggle with many of the same challenges. This monograph focuses on their journeys and provides insights for educators interested in learning about how institutions across the globe provide supports to students dealing with first-year transition issues. Based on the successful…

GLOBE ONE: A Community-Based Environmental Field Campaign

Treesearch

Rebecca Boger; Peggy LeMone; John McLaughlin; Sharon Sikora; Sandra Henderson

2006-01-01

The Global Learning and Observations to Benefit the Environment (GLOBE) program is an international environmental science and education program involving scientists, teachers and students in the collection, analysis, and display of data used in environmental monitoring and research. Since its formation in 1994, students have collected over 11 million data points in...

The Significance of Ongoing Teacher Support in Earth Science Education Programs: Evidence from the GLOBE Program

NASA Astrophysics Data System (ADS)

Penuel, B.; Korbak, C.; Shear, L.

2003-12-01

The GLOBE program provides a rich context for examining issues concerning implementation of inquiry-oriented, scientist-driven educational programs, because the program has both a history of collecting evaluation data on implementation and mechanisms for capturing program activity as it occurs. In this paper, researchers from SRI International's evaluation team explore the different roles that regional partners play in preparing and supporting teachers to implement the GLOBE Program, an international inquiry-based Earth science education initiative that has trained over 14,000 teachers worldwide. GLOBE program evaluation results show the program can be effective in increasing students' inquiry skills, but that the program is also hard for teachers to implement (Means et al., 2001; Penuel et al., 2002). An analysis of GLOBE's regional partner organizations, which are tasked with preparing teachers to implement its data collection and reporting protocols with students, shows that some partners are more successful than others. This paper reports findings from a quantitative analysis of the relationship between data reporting and partner support activities and from case studies of two such regional partners focused on analyzing what makes them successful. The first analysis examined associations between partner training and support activities and data reporting. For this analysis, we used data from the GLOBE Student Data Archive matched with survey data collected from a large sample of GLOBE teachers as part of SRI's Year 5 evaluation of GLOBE. Our analyses point to the central importance of mentoring and material support to teachers. We found that incentives, mentoring, and other on-site support to teachers have a statistically significant association with higher data reporting levels. We also found that at present, teachers access these supports less often than they access listservs and e-mail communication with teachers after GLOBE training. As a follow-up to this

Selection Algorithm for the CALIPSO Lidar Aerosol Extinction-to-Backscatter Ratio

NASA Technical Reports Server (NTRS)

Omar, Ali H.; Winker, David M.; Vaughan, Mark A.

2006-01-01

The extinction-to-backscatter ratio (S(sub a)) is an important parameter used in the determination of the aerosol extinction and subsequently the optical depth from lidar backscatter measurements. We outline the algorithm used to determine Sa for the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) lidar. S(sub a) for the CALIPSO lidar will either be selected from a look-up table or calculated using the lidar measurements depending on the characteristics of aerosol layer. Whenever suitable lofted layers are encountered, S(sub a) is computed directly from the integrated backscatter and transmittance. In all other cases, the CALIPSO observables: the depolarization ratio, delta, the layer integrated attenuated backscatter, beta, and the mean layer total attenuated color ratio, gamma, together with the surface type, are used to aid in aerosol typing. Once the type is identified, a look-up-table developed primarily from worldwide observations, is used to determine the S(sub a) value. The CALIPSO aerosol models include desert dust, biomass burning, background, polluted continental, polluted dust, and marine aerosols.

Quantitative broadband ultrasonic backscatter - An approach to nondestructive evaluation in acoustically inhomogeneous materials

NASA Technical Reports Server (NTRS)

Odonnell, M.; Miller, J. G.

1981-01-01

The use of a broadband backscatter technique to obtain the frequency dependence of the longitudinal-wave ultrasonic backscatter coefficient from a collection of scatterers in a solid is investigated. Measurements of the backscatter coefficient were obtained over the range of ultrasonic wave vector magnitude-glass sphere radius product between 0.1 and 3.0 from model systems consisting of dilute suspensions of randomly distributed crown glass spheres in hardened polyester resin. The results of these measurements were in good agreement with theoretical prediction. Consequently, broadband measurements of the ultrasonic backscatter coefficient may represent a useful approach toward characterizing the physical properties of scatterers in intrinsically inhomogeneous materials such as composites, metals, and ceramics, and may represent an approach toward nondestructive evaluation of these materials.

Effect of curvature on the backscattering from leaves

NASA Technical Reports Server (NTRS)

Sarabandi, K.; Senior, T. B. A.; Ulaby, F. T.

1988-01-01

Using a model previously developed for the backscattering cross section of a planar leaf at X-band frequencies and above, the effect of leaf curvature is examined. For normal incidence on a rectangular section of a leaf curved in one and two dimensions, an integral expression for the backscattered field is evaluated numerically and by a stationary phase approximation, leading to a simple analytical expression for the cross section reduction produced by the curvature. Numerical results based on the two methods are virtually identical, and in excellent agreement with measured data for rectangular sections of coleus leaves applied to the surfaces of styrofoam cylinders and spheres of different radii.

Simulation of multistatic and backscattering cross sections for airborne radar

NASA Astrophysics Data System (ADS)

Biggs, Albert W.

1986-07-01

In order to determine susceptibilities of airborne radar to electronic countermeasures and electronic counter-countermeasures simulations of multistatic and backscattering cross sections were developed as digital modules in the form of algorithms. Cross section algorithms are described for prolate (cigar shape) and oblate (disk shape) spheroids. Backscattering cross section algorithms are also described for different categories of terrain. Backscattering cross section computer programs were written for terrain categorized as vegetation, sea ice, glacial ice, geological (rocks, sand, hills, etc.), oceans, man-made structures, and water bodies. PROGRAM SIGTERRA is a file for backscattering cross section modules of terrain (TERRA) such as vegetation (AGCROP), oceans (OCEAN), Arctic sea ice (SEAICE), glacial snow (GLASNO), geological structures (GEOL), man-made structures (MAMMAD), or water bodies (WATER). AGCROP describes agricultural crops, trees or forests, prairies or grassland, and shrubs or bush cover. OCEAN has the SLAR or SAR looking downwind, upwind, and crosswind at the ocean surface. SEAICE looks at winter ice and old or polar ice. GLASNO is divided into a glacial ice and snow or snowfields. MANMAD includes buildings, houses, roads, railroad tracks, airfields and hangars, telephone and power lines, barges, trucks, trains, and automobiles. WATER has lakes, rivers, canals, and swamps. PROGRAM SIGAIR is a similar file for airborne targets such as prolate and oblate spheroids.

Compton backscattered collimated x-ray source

DOEpatents

Ruth, R.D.; Huang, Z.

1998-10-20

A high-intensity, inexpensive and collimated x-ray source is disclosed for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications. 4 figs.

Compton backscattered collimated x-ray source

DOEpatents

Ruth, Ronald D.; Huang, Zhirong

1998-01-01

A high-intensity, inexpensive and collimated x-ray source for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications.

Compton backscattered collmated X-ray source

DOEpatents

Ruth, Ronald D.; Huang, Zhirong

2000-01-01

A high-intensity, inexpensive and collimated x-ray source for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications.

Natural variability of tropical upper stratospheric ozone inferred from the Atmosphere Explorer backscatter ultraviolet experiment

NASA Technical Reports Server (NTRS)

Frederick, J. E.; Abrams, R. B.; Dasgupta, R.; Guenther, B.

1981-01-01

Analysis of backscattered ultraviolet radiances observed at tropical latitudes by the Atmosphere Explorer-E satellite reveals both annual and semiannual cycles in upper stratospheric ozone. The annual variation dominates the signal at wavelengths which sense ozone primarily above 45 km while below this, to the lowest altitude sensed, 35 km, the semiannual component has comparable amplitude. Comparison of radiance measurements taken with the same instrument at solar minimum during 1976 and solar maximum in 1979 show no significant differences. This suggests that variations in upper stratospheric ozone over the solar cycle are small, although the data presently available do not allow a definite conclusion.

Comparison of modeled backscatter with SAR data at P-band

NASA Technical Reports Server (NTRS)

Wang, Yong; Davis, Frank W.; Melack, John M.

1992-01-01

In recent years several analytical models were developed to predict microwave scattering by trees and forest canopies. These models contribute to the understanding of radar backscatter over forested regions to the extent that they capture the basic interactions between microwave radiation and tree canopies, understories, and ground layers as functions of incidence angle, wavelength, and polarization. The Santa Barbara microwave model backscatter model for woodland (i.e. with discontinuous tree canopies) combines a single-tree backscatter model and a gap probability model. Comparison of model predictions with synthetic aperture radar (SAR) data and L-band (lambda = 0.235 m) is promising, but much work is still needed to test the validity of model predictions at other wavelengths. The validity of the model predictions at P-band (lambda = 0.68 m) for woodland stands at our Mt. Shasta test site was tested.

A simplified technique for in situ excision of cornea and evisceration of retinal tissue from human ocular globe.

PubMed

Parekh, Mohit; Ferrari, Stefano; Di Iorio, Enzo; Barbaro, Vanessa; Camposampiero, Davide; Karali, Marianthi; Ponzin, Diego; Salvalaio, Gianni

2012-06-12

Enucleation is the process of retrieving the ocular globe from a cadaveric donor leaving the rest of the globe undisturbed. Excision refers to the retrieval of ocular tissues, especially cornea, by cutting it separate from the ocular globe. Evisceration is the process of removing the internal organs referred here as retina. The ocular globe consists of the cornea, the sclera, the vitreous body, the lens, the iris, the retina, the choroid, muscles etc (Suppl. Figure 1). When a patient is suffering from corneal damage, the cornea needs to be removed and a healthy one must be transplanted by keratoplastic surgeries. Genetic disorders or defects in retinal function can compromise vision. Human ocular globes can be used for various surgical procedures such as eye banking, transplantation of human cornea or sclera and research on ocular tissues. However, there is little information available on human corneal and retinal excision, probably due to the limited accessibility to human tissues. Most of the studies describing similar procedures are performed on animal models. Research scientists rely on the availability of properly dissected and well-conserved ocular tissues in order to extend the knowledge on human eye development, homeostasis and function. As we receive high amount of ocular globes out of which approximately 40% (Table 1) of them are used for research purposes, we are able to perform huge amount of experiments on these tissues, defining techniques to excise and preserve them regularly. The cornea is an avascular tissue which enables the transmission of light onto the retina and for this purpose should always maintain a good degree of transparency. Within the cornea, the limbus region, which is a reservoir of the stem cells, helps the reconstruction of epithelial cells and restricts the overgrowth of the conjunctiva maintaining corneal transparency and clarity. The size and thickness of the cornea are critical for clear vision, as changes in either of them

GLOBE in the Czech Republic: A Program Evaluation

ERIC Educational Resources Information Center

Cincera, Jan; Maskova, Veronika

2011-01-01

The article presents results of the evaluation of the GLOBE program (Global Learning and Observations to Benefit the Environment) in the Czech Republic. The evaluation explores the implementation of the program in schools and its impact on research skills. Four hundred and sixty six pupils, aged 13, from 28 different schools participated in the…

Perspectives on Teaching Economics from around the Globe

ERIC Educational Resources Information Center

Round, David K.; Shanahan, Martin

2005-01-01

From July 13 to 16, 2004, colleagues from around the world gathered at the University of South Australia to present and discuss their research on economic education. The conference, entitled "What We Teach and How We Teach It: Perspectives on Economics from around the Globe," was presented by The Centre for Regulation and Market Analysis…

Relationship between wind, waves and radar backscatter

NASA Technical Reports Server (NTRS)

Katsaros, Kristina B.; Ataktuerk, Serhad S.

1991-01-01

The aim of the research was to investigate the relationship between wind, waves, and radar backscatter from water surface. To this end, three field experiments with periods of 2 to 4 weeks were carried out during summer months in 1988, 1989 and 1990. For these periods, the University of Washington group provided (1) environmental parameters such as wind speed, wind stress, and atmospheric stratification through measurements of surface fluxes (of momentum, sensible heat and latent heat) and of air and water temperatures; and (2) wave height spectra including both the dominant waves and the short gravity-capillary waves. Surface flux measurements were performed by using our well tested instruments: a K-Gill twin propeller-vane anemometer and a fast response thermocouple psychrometer. Wave heights were measured by a resistance wire wave gauge. The University of Kansas group was responsible for the operation of the microwave radars.

Monte Carlo investigation of backscatter point spread function for x-ray imaging examinations

NASA Astrophysics Data System (ADS)

Xiong, Zhenyu; Vijayan, Sarath; Rudin, Stephen; Bednarek, Daniel R.

2017-03-01

X-ray imaging examinations, especially complex interventions, may result in relatively high doses to the patient's skin inducing skin injuries. A method was developed to determine the skin-dose distribution for non-uniform x-ray beams by convolving the backscatter point-spread-function (PSF) with the primary-dose distribution to generate the backscatter distribution that, when added to the primary dose, gives the total-dose distribution. This technique was incorporated in the dose-tracking system (DTS), which provides a real-time color-coded 3D-mapping of skin dose during fluoroscopic procedures. The aim of this work is to investigate the variation of the backscatter PSF with different parameters. A backscatter PSF of a 1-mm x-ray beam was generated by EGSnrc Monte-Carlo code for different x-ray beam energies, different soft-tissue thickness above bone, different bone thickness and different entrance-beam angles, as well as for different locations on the SK-150 anthropomorphic head phantom. The results show a reduction of the peak scatter to primary dose ratio of 48% when X-ray beam voltage is increased from 40 keV to 120 keV. The backscatter dose was reduced when bone was beneath the soft tissue layer and this reduction increased with thinner soft tissue and thicker bone layers. The backscatter factor increased about 21% as the angle of incidence of the beam with the entrance surface decreased from 90° (perpendicular) to 30°. The backscatter PSF differed for different locations on the SK-150 phantom by up to 15%. The results of this study can be used to improve the accuracy of dose calculation when using PSF convolution in the DTS.

Bringing the Science of Climate Change to Elementary Students with new Classroom Activities from Elementary GLOBE

NASA Astrophysics Data System (ADS)

Gardiner, L. S.; Hatheway, B.; Taylor, J.; Chambers, L. H.; Stanitski, D.

2016-12-01

To address the dearth of climate education resources at the elementary level, we have developed a new module of Elementary GLOBE to showcase the science of climate change for young learners. Elementary GLOBE builds K-4 student understanding of the science concepts and the practices of science research. At the heart of each Elementary GLOBE module is a fiction storybook, describing how three kids investigate a science question. Accompanying classroom activities allow students to explore the science concepts in the book in more depth and in a context appropriate for young learners. The book for the Elementary GLOBE climate module, "What in the World Is Happening to Our Climate?," is the account of an adventure to explore climate change, how it is affecting melting glacial ice and sea level rise, and how climate change is a problem that can be solved. Three hands-on activities, which will be presented at this session, allow students to explore the topics in greater depth including differences between weather and climate, how sea level rise affects coastal areas, and how they can shrink their carbon footprint to help address recent climate change. Each activity includes instructions for teachers, background information, and activity sheets for students, and is aligned to the Next Generation Science Standards and Common Core Math and Language Arts Standards. The storybook and activities were field tested in classrooms and reviewed by climate and Earth system scientists as well as elementary education and climate education specialists and educators to ensure scientific accuracy and clear explanations, and that the resources are age appropriate and reflect the needs of the climate education community. Other Elementary GLOBE modules include the science of seasonal change, water, soil, clouds, aerosols, and Earth as a system. All Elementary GLOBE educational resources are freely available online (www.globe.gov/elementaryglobe).

Development of a Coded Aperture X-Ray Backscatter Imager for Explosive Device Detection

NASA Astrophysics Data System (ADS)

Faust, Anthony A.; Rothschild, Richard E.; Leblanc, Philippe; McFee, John Elton

2009-02-01

Defence R&D Canada has an active research and development program on detection of explosive devices using nuclear methods. One system under development is a coded aperture-based X-ray backscatter imaging detector designed to provide sufficient speed, contrast and spatial resolution to detect antipersonnel landmines and improvised explosive devices. The successful development of a hand-held imaging detector requires, among other things, a light-weight, ruggedized detector with low power requirements, supplying high spatial resolution. The University of California, San Diego-designed HEXIS detector provides a modern, large area, high-temperature CZT imaging surface, robustly packaged in a light-weight housing with sound mechanical properties. Based on the potential for the HEXIS detector to be incorporated as the detection element of a hand-held imaging detector, the authors initiated a collaborative effort to demonstrate the capability of a coded aperture-based X-ray backscatter imaging detector. This paper will discuss the landmine and IED detection problem and review the coded aperture technique. Results from initial proof-of-principle experiments will then be reported.

TU-D-209-02: A Backscatter Point Spread Function for Entrance Skin Dose Determination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayan, S; Xiong, Z; Shankar, A

Purpose: To determine the distribution of backscattered radiation to the skin resulting from a non-uniform distribution of primary radiation through convolution with a backscatter point spread function (PSF). Methods: A backscatter PSF is determined using Monte Carlo simulation of a 1 mm primary beam incident on a 30 × 30 cm × 20 cm thick PMMA phantom using EGSnrc software. A primary profile is similarly obtained without the phantom and the difference from the total provides the backscatter profile. This scatter PSF characterizes the backscatter spread for a “point” primary interaction and can be convolved with the entrance primary dosemore » distribution to obtain the total entrance skin dose. The backscatter PSF was integrated into the skin dose tracking system (DTS), a graphical utility for displaying the color-coded skin dose distribution on a 3D graphic of the patient during interventional fluoroscopic procedures. The backscatter convolution method was validated for the non-uniform beam resulting from the use of an ROI attenuator. The ROI attenuator is a copper sheet with about 20% primary transmission (0.7 mm thick) containing a circular aperture; this attenuator is placed in the beam to reduce dose in the periphery while maintaining full dose in the region of interest. The DTS calculated primary plus backscatter distribution is compared to that measured with GafChromic film and that calculated using EGSnrc Monte-Carlo software. Results: The PSF convolution method used in the DTS software was able to account for the spread of backscatter from the ROI region to the region under the attenuator. The skin dose distribution determined using DTS with the ROI attenuator was in good agreement with the distributions measured with Gafchromic film and determined by Monte Carlo simulation Conclusion: The PSF convolution technique provides an accurate alternative for entrance skin dose determination with non-uniform primary x-ray beams. Partial support from NIH

Comparisons of ionospheric electron density distributions reconstructed by GPS computerized tomography, backscatter ionograms, and vertical ionograms

NASA Astrophysics Data System (ADS)

Zhou, Chen; Lei, Yong; Li, Bofeng; An, Jiachun; Zhu, Peng; Jiang, Chunhua; Zhao, Zhengyu; Zhang, Yuannong; Ni, Binbin; Wang, Zemin; Zhou, Xuhua

2015-12-01

Global Positioning System (GPS) computerized ionosphere tomography (CIT) and ionospheric sky wave ground backscatter radar are both capable of measuring the large-scale, two-dimensional (2-D) distributions of ionospheric electron density (IED). Here we report the spatial and temporal electron density results obtained by GPS CIT and backscatter ionogram (BSI) inversion for three individual experiments. Both the GPS CIT and BSI inversion techniques demonstrate the capability and the consistency of reconstructing large-scale IED distributions. To validate the results, electron density profiles obtained from GPS CIT and BSI inversion are quantitatively compared to the vertical ionosonde data, which clearly manifests that both methods output accurate information of ionopsheric electron density and thereby provide reliable approaches to ionospheric soundings. Our study can improve current understanding of the capability and insufficiency of these two methods on the large-scale IED reconstruction.

A 3D Planetary Neocartographic Tool in Education: A Game on Virtual Moon and Mars Globes

NASA Astrophysics Data System (ADS)

Hargitai, H.; Simonné-Dombóvári, E.; Gede, M.

2012-03-01

The paper describes the educational use of online virtual globes of Mars and the Moon. The game uses topographic globes of Mars (MOLA) and the Moon (LRO DTM) that includes IAU nomenclature + informal names. Students have to position the points described.

Two-color short-pulse laser altimeter measurements of ocean surface backscatter

NASA Technical Reports Server (NTRS)

Abshire, James B.; Mcgarry, Jan F.

1987-01-01

The timing and correlation properties of pulsed laser backscatter from the ocean surface have been measured with a two-color short-pulse laser altimeter. The Nd:YAG laser transmitted 70- and 35-ps wide pulses simultaneously at 532 and 355 nm at nadir, and the time-resolved returns were recorded by a receiver with 800-ps response time. The time-resolved backscatter measured at both 330-m and 1291-m altitudes showed little pulse broadening due to the submeter laser spot size. The differential delay of the 355-nm and 532-nm backscattered waveforms were measured with a rms error of about 75 ps. The change in aircraft altitudes also permitted the change in atmospheric pressure to be estimated by using the two-color technique.

Revised ocean backscatter models at C and Ku band under high-wind conditions

NASA Astrophysics Data System (ADS)

Donnelly, William J.; Carswell, James R.; McIntosh, Robert E.; Chang, Paul S.; Wilkerson, John; Marks, Frank; Black, Peter G.

1999-05-01

A series of airborne scatterometer experiments designed to collect C and Ku band ocean backscatter data in regions of high ocean surface winds has recently been completed. More than 100 hours of data were collected using the University of Massachusetts C and Ku band scatterometers, CSCAT and KUSCAT. These instruments measure the full azimuthal normalized radar cross section (NRCS) of a common surface area of the ocean simultaneously at four incidence angles. Our results demonstrate limitations of the current empirical models, C band geophysical model function 4 (CMOD4), SeaSat scatterometer 2 (SASS 2), and NASA scatterometer 1 (NSCAT) 1, that relate ocean backscatter to the near-surface wind at high wind speeds. The discussion focuses on winds in excess of 15 m s-1 in clear atmospheric conditions. The scatterometer data are collocated with measurements from ocean data buoys and Global Positioning System dropsondes, and a Fourier analysis is performed as a function of wind regime. A three-term Fourier series is fit to the backscatter data, and a revised set of coefficients is tabulated. These revised models, CMOD4HW and KUSCAT 1, are the basis for a discussion of the NRCS at high wind speeds. Our scatterometer data show a clear overprediction of the derived NRCS response to high winds based on the CMOD4, SASS 2, and NSCAT 1 models. Furthermore, saturation of the NRCS response begins to occur above 15 m s-1. Sensitivity of the upwind and crosswind response is discussed with implications toward high wind speed retrieval.

Comparison of Lidar Backscatter with Particle Distribution and GOES-7 Data in Hurricane Juliette

NASA Technical Reports Server (NTRS)

Jarzembski, Maurice A.; Srivastava, Vandana; McCaul, Eugene W., Jr.; Jedlovec, Gary J.; Atkinson, Robert J.; Pueschel, Rudolf F.; Cutten, Dean R.

1997-01-01

Measurements of calibrated backscatter, using two continuous wave Doppler lidars operating at wavelengths 9.1 and 10.6 micrometers were obtained along with cloud particle size distributions in Hurricane Juliette on 21 September 1995 at altitude approximately 11.7 km. Agreement between backscatter from the two lidars and with the cloud particle size distribution is excellent. Features in backscatter and particle number density compare well with concurrent GOES-7 infrared images.

Laser-based air data system for aircraft control using Raman and elastic backscatter for the measurement of temperature, density, pressure, moisture, and particle backscatter coefficient.

PubMed

Fraczek, Michael; Behrendt, Andreas; Schmitt, Nikolaus

2012-01-10

Flight safety in all weather conditions demands exact and reliable determination of flight-critical air parameters. Air speed, temperature, density, and pressure are essential for aircraft control. Conventional air data systems can be impacted by probe failure caused by mechanical damage from hail, volcanic ash, and icing. While optical air speed measurement methods have been discussed elsewhere, in this paper, a new concept for optically measuring the air temperature, density, pressure, moisture, and particle backscatter is presented, being independent on assumptions on the atmospheric state and eliminating the drawbacks of conventional aircraft probes by providing a different measurement principle. The concept is based on a laser emitting laser pulses into the atmosphere through a window and detecting the signals backscattered from a fixed region just outside the disturbed area of the fuselage flows. With four receiver channels, different spectral portions of the backscattered light are extracted. The measurement principle of air temperature and density is based on extracting two signals out of the rotational Raman (RR) backscatter signal of air molecules. For measuring the water vapor mixing ratio-and thus the density of the moist air-a water vapor Raman channel is included. The fourth channel serves to detect the elastic backscatter signal, which is essential for extending the measurements into clouds. This channel contributes to the detection of aerosols, which is interesting for developing a future volcanic ash warning system for aircraft. Detailed and realistic optimization and performance calculations have been performed based on the parameters of a first prototype of such a measurement system. The impact and correction of systematic error sources, such as solar background at daytime and elastic signal cross talk appearing in optically dense clouds, have been investigated. The results of the simulations show the high potential of the proposed system for

The GLOBE/Madagascar Malaria Project: Creating Student/Educator/Scientist Partnerships With Regional Impact

NASA Astrophysics Data System (ADS)

Brooks, D.; Boger, R.; Rafalimanana, A.

2006-05-01

Malaria is a parasitic disease spread by mosquitoes in the genus Anopheles. It causes more than 300,000,000 acute illnesses and more than one million deaths annually, including the death of one African child every 30 seconds. Recent epidemiological trends include increases in malaria mortality and the emergence of drug-resistant parasites. Some experts believe that predicted climate changes during the 21st century will bring malaria to areas where it is not now common. The GLOBE Program is currently collaborating with students, educators, scientists, health department officials, and government officials in Madagascar to develop a program that combines existing GLOBE protocols for measuring atmospheric and water quality parameters with a new protocol for collecting and identifying mosquito larvae at the genus (Anopheles and non-Anopheles) level. There are dozens of Anopheles species and sub-species that are adapted to a wide range of micro-environmental conditions encountered in Madagascar's variable climate. Local data collection is essential because mosquitoes typically spend their entire lives within a few kilometers of their breeding sites. The GLOBE Program provides an ideal framework for such a project because it offers a highly structured system for defining experiment protocols that ensure consistent procedures, a widely dispersed network of observing sites, and a centralized data collection and reporting system. Following a series of training activities in 2005, students in Madagascar are now beginning to collect data. Basic environmental parameters and first attempts at larvae collection and identification are presented. Results from this project can be used to increase public awareness of malaria, to provide new scientific data concerning environmental impacts on mosquito breeding, and to provide better information for guiding effective mitigation strategies. Problems encountered include difficulties in visiting and communicating with remote school sites

The Use of Virtual Globes as a Spatial Teaching Tool with Suggestions for Metadata Standards

ERIC Educational Resources Information Center

Schultz, Richard B.; Kerski, Joseph J.; Patterson, Todd C.

2008-01-01

Virtual Globe software has become extremely popular both inside and outside of educational settings. This software allows users to explore the Earth in three dimensions while streaming satellite imagery, elevation, and other data from the Internet. Virtual Globes, such as Google Earth, NASA World Wind, and ESRI's ArcGIS Explorer can be effectively…

Standard-target calibration of an acoustic backscatter system

USGS Publications Warehouse

Foote, Kenneth G.; Martini, Marinna A.

2010-01-01

The standard-target method used to calibrate scientific echo sounders and other scientific sonars by a single, solid elastic sphere is being adapted to acoustic backscatter (ABS) systems. Its first application, to the AQUAscat 1000, is described. The on-axis sensitivity and directional properties of transducer beams at three operating frequencies, nominally 1, 2.5, and 4 MHz, have been determined using a 10-mm-diameter sphere of tungsten carbide with 6% cobalt binder. Preliminary results are reported for the 1-MHz transducer. Their application to measurements of suspended sediment made in situ with the same device is described. This will enable the data to be expressed directly in physical units of volume backscattering.

Successful medical treatment for globe penetration following tooth extraction in a dog.

PubMed

Guerreiro, Cleo E; Appelboam, Helen; Lowe, Robert C

2014-03-01

A five-year-old entire male Tibetan Terrier was referred for left-sided periorbital swelling and blepharospasm 4 days following ipsilateral maxillary tooth extraction. Examination of the left eye revealed mild exophthalmos, pain on retropulsion, and absent menace response and pupillary light reflexes. Examination of the posterior segment was not possible owing to the anterior segment pathology. Differential diagnoses considered were iatrogenic globe penetration and peribulbar abscess/cellulitis. Ocular ultrasound was consistent with a penetrating wound to the globe. Treatment with systemic prednisolone and marbofloxacin, and topical atropine sulfate 1%, prednisolone acetate, and brinzolamide was started. Marked clinical improvement allowed visual confirmation of the perforation. Oral prednisolone was tapered over the following 10 weeks. At final re-examination (10 months), the patient was visual, and fundic examination revealed an additional chorioretinal scar, most likely an exit wound that was obscured by vitreal debris on initial examinations. Neither scar was associated with retinal detachment. To the authors' knowledge, this is the first reported case of successful medical management of iatrogenic globe penetration following exodontic procedures. © 2013 American College of Veterinary Ophthalmologists.

Development of an Anatomically Accurate Finite Element Human Ocular Globe Model for Blast-Related Fluid-Structure Interaction Studies

DTIC Science & Technology

2017-02-01

ARL-TR-7945 ● FEB 2017 US Army Research Laboratory Development of an Anatomically Accurate Finite Element Human Ocular Globe...ARL-TR-7945 ● FEB 2017 US Army Research Laboratory Development of an Anatomically Accurate Finite Element Human Ocular Globe Model... Finite Element Human Ocular Globe Model for Blast-Related Fluid-Structure Interaction Studies 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

Forty-five degree backscattering-mode nonlinear absorption imaging in turbid media.

PubMed

Cui, Liping; Knox, Wayne H

2010-01-01

Two-color nonlinear absorption imaging has been previously demonstrated with endogenous contrast of hemoglobin and melanin in turbid media using transmission-mode detection and a dual-laser technology approach. For clinical applications, it would be generally preferable to use backscattering mode detection and a simpler single-laser technology. We demonstrate that imaging in backscattering mode in turbid media using nonlinear absorption can be obtained with as little as 1-mW average power per beam with a single laser source. Images have been achieved with a detector receiving backscattered light at a 45-deg angle relative to the incoming beams' direction. We obtain images of capillary tube phantoms with resolution as high as 20 microm and penetration depth up to 0.9 mm for a 300-microm tube at SNR approximately 1 in calibrated scattering solutions. Simulation results of the backscattering and detection process using nonimaging optics are demonstrated. A Monte Carlo-based method shows that the nonlinear signal drops exponentially as the depth increases, which agrees well with our experimental results. Simulation also shows that with our current detection method, only 2% of the signal is typically collected with a 5-mm-radius detector.

Analysis of seafloor backscatter strength dependence on the survey azimuth using multibeam echosounder data

NASA Astrophysics Data System (ADS)

Lurton, Xavier; Eleftherakis, Dimitrios; Augustin, Jean-Marie

2018-06-01

The sediment backscatter strength measured by multibeam echosounders is a key feature for seafloor mapping either qualitative (image mosaics) or quantitative (extraction of classifying features). An important phenomenon, often underestimated, is the dependence of the backscatter level on the azimuth angle imposed by the survey line directions: strong level differences at varying azimuth can be observed in case of organized roughness of the seabed, usually caused by tide currents over sandy sediments. This paper presents a number of experimental results obtained from shallow-water cruises using a 300-kHz multibeam echosounder and specially dedicated to the study of this azimuthal effect, with a specific configuration of the survey strategy involving a systematic coverage of reference areas following "compass rose" patterns. The results show for some areas a very strong dependence of the backscatter level, up to about 10-dB differences at intermediate oblique angles, although the presence of these ripples cannot be observed directly—neither from the bathymetry data nor from the sonar image, due to the insufficient resolution capability of the sonar. An elementary modeling of backscattering from rippled interfaces explains and comforts these observations. The consequences of this backscatter dependence upon survey azimuth on the current strategies of backscatter data acquisition and exploitation are discussed.

Coherent and incoherent ultrasound backscatter from cell aggregates.

PubMed

de Monchy, Romain; Destrempes, François; Saha, Ratan K; Cloutier, Guy; Franceschini, Emilie

2016-09-01

The effective medium theory (EMT) was recently developed to model the ultrasound backscatter from aggregating red blood cells [Franceschini, Metzger, and Cloutier, IEEE Trans. Ultrason. Ferroelectr. Freq. Control 58, 2668-2679 (2011)]. The EMT assumes that aggregates can be treated as homogeneous effective scatterers, which have effective properties determined by the aggregate compactness and the acoustical characteristics of the cells and the surrounding medium. In this study, the EMT is further developed to decompose the differential backscattering cross section of a single cell aggregate into coherent and incoherent components. The coherent component corresponds to the squared norm of the average scattering amplitude from the effective scatterer, and the incoherent component considers the variance of the scattering amplitude (i.e., the mean squared norm of the fluctuation of the scattering amplitude around its mean) within the effective scatterer. A theoretical expression for the incoherent component based on the structure factor is proposed and compared with another formulation based on the Gaussian direct correlation function. This theoretical improvement is assessed using computer simulations of ultrasound backscatter from aggregating cells. The consideration of the incoherent component based on the structure factor allows us to approximate the simulations satisfactorily for a product of the wavenumber times the aggregate radius kr ag around 2.

A novel biometric X-ray backscatter inspection of dangerous materials based on a lobster-eye objective

NASA Astrophysics Data System (ADS)

Xu, Jie; Wang, Xin; Mu, Baozhong; Zhan, Qi; Xie, Qing; Li, Yaran; Chen, Yifan; He, Yanan

2016-10-01

In order to counter drug-related crimes effectively, and to safeguard homeland security as well as public safety, it is important to inspect drugs, explosives and other contraband quickly and accurately from the express mail system, luggage, vehicles and other objects. In this paper, we discuss X-ray backscatter inspection system based on a novel lobster-eye X-ray objective, which is an effective inspection technology for drugs, explosives and other contraband inspection. Low atomic number materials, such as drugs and explosives, leads to strong Compton scattering after irradiated by X-ray, which is much stronger than high atomic number material, such as common metals, etc. By detecting the intensity of scattering signals, it is possible to distinguish between organics and inorganics. The lobster-eye X-ray optical system imitates the reflective eyes of lobsters, which field of view can be made as large as desired and it is practical to achieve spatial resolution of several millimeters for finite distance detection. A novel lobster-eye X-ray objective is designed based on modifying Schmidt geometry by using multi-lens structure, so as to reduce the difference of resolution between the horizontal and vertical directions. The demonstration experiments of X-ray backscattering imaging were carried out. A suitcase, a wooden box and a tire with several typical samples hidden in them were imaged by the X-ray backscattering inspection system based on a lobster-eye X-ray objective. The results show that this X-ray backscattering inspection system can get a resolution of less than five millimeters under the FOV of more than two hundred millimeters with 0.5 meter object distance, which can still be improved.

Nail gun-induced open-globe injuries: a 10-year retrospective review.

PubMed

Kolomeyer, Anton M; Shah, Avni; Bauza, Alain M; Langer, Paul D; Zarbin, Marco A; Bhagat, Neelakshi

2014-02-01

To describe the characteristics of nail gun-related open-globe injuries. Retrospective series of all patients presenting with open globes secondary to nail gun injury from 2000 to 2010. Data were collected on demographics, setting of accident, presenting clinical examination findings, visual acuity, management, surgical procedures needed, and long-term outcomes. Forty-two patients (43 eyes; mean age, 31.6 years; 100% male; 79% Hispanic) suffered open-globe injury from nail gun accidents. Thirty-seven eyes (86%) sustained injury at work. One of 15 (6.7%) patients, on whom data were available, wore protective eyewear during the incident. Entrance wounds were classified into Zone I (n = 24 [56%]), Zone II (n = 12 [28%]), and Zone III (n = 7 [16%]). Six eyes (14%) had retained intraocular foreign bodies. Mean presenting logarithm of the minimum angle of resolution visual acuity was 1.64 ± 0.83, whereas mean final logarithm of the minimum angle of resolution visual acuity was 1.01 ± 0.96 (P = 0.004). Two eyes (4.7%) had no light perception vision at final examination. Seventeen (40%) patients developed a traumatic cataract, and 2 (4.7%) had dislocated lens fragments. Most common findings on presentation included vitreous hemorrhage (n = 30 [70%]) and hyphema (n = 28 [64%]). Two eyes (4.7%) had a retinal detachment at presentation, and 10 (23%) developed a retinal detachment during follow-up visits. Anatomical success was observed in 11 eyes (92%) with a retinal detachment. Three eyes (7.0%) became phthisical or prephthisical, and 1 was enucleated for severe pain. No eyes developed endophthalmitis or sympathetic ophthalmia. This is the largest compilation of nail gun-related open-globe injury reported to date. Posterior segment complications, noted in the majority of cases, likely contributed to the overall guarded visual outcomes. Preventative measures for eye protection should be strictly followed while using nail guns.

Comparison of SeaWinds Backscatter Imaging Algorithms

PubMed Central

Long, David G.

2017-01-01

This paper compares the performance and tradeoffs of various backscatter imaging algorithms for the SeaWinds scatterometer when multiple passes over a target are available. Reconstruction methods are compared with conventional gridding algorithms. In particular, the performance and tradeoffs in conventional ‘drop in the bucket’ (DIB) gridding at the intrinsic sensor resolution are compared to high-spatial-resolution imaging algorithms such as fine-resolution DIB and the scatterometer image reconstruction (SIR) that generate enhanced-resolution backscatter images. Various options for each algorithm are explored, including considering both linear and dB computation. The effects of sampling density and reconstruction quality versus time are explored. Both simulated and actual data results are considered. The results demonstrate the effectiveness of high-resolution reconstruction using SIR as well as its limitations and the limitations of DIB and fDIB. PMID:28828143

Diffuse optical microscopy for quantification of depth-dependent epithelial backscattering in the cervix

NASA Astrophysics Data System (ADS)

Bodenschatz, Nico; Lam, Sylvia; Carraro, Anita; Korbelik, Jagoda; Miller, Dianne M.; McAlpine, Jessica N.; Lee, Marette; Kienle, Alwin; MacAulay, Calum

2016-06-01

A fiber optic imaging approach is presented using structured illumination for quantification of almost pure epithelial backscattering. We employ multiple spatially modulated projection patterns and camera-based reflectance capture to image depth-dependent epithelial scattering. The potential diagnostic value of our approach is investigated on cervical ex vivo tissue specimens. Our study indicates a strong backscattering increase in the upper part of the cervical epithelium caused by dysplastic microstructural changes. Quantization of relative depth-dependent backscattering is confirmed as a potentially useful diagnostic feature for detection of precancerous lesions in cervical squamous epithelium.

Google Earth: A Virtual Globe for Elementary Geography

ERIC Educational Resources Information Center

Britt, Judy; LaFontaine, Gus

2009-01-01

Originally called Earth Viewer in 2004, Google Earth was the first virtual globe easily available to the ordinary user of the Internet. Google Earth, at earth.google.com, is a free, 3-dimensional computer model of Earth, but that means more than just a large collection of pretty pictures. It allows the viewer to "fly" anywhere on Earth "to view…

What are the controls on mountain snowmelt and runoff around the globe?

NASA Astrophysics Data System (ADS)

Painter, T. H.

2017-12-01

The Anthropocene has seen a marked expulsion of mass from mountain glaciers to oceans and earlier snowmelt that evacuates the mountains earlier in the year. The loss of ice mass and snow cover is often attributed to increasing temperatures. However, process studies across the last two decades indicate that acceleration of melt by dust/black carbon (BC) may dominate in some regions. Process studies with detailed energy balance measurements around the globe are relatively sparse but strongly suggestive of the impact of dust and BC. Mesoscale and global scale modeling have recently taken on radiative transfer modeling of snow albedo that accounts for changes in grain size and dust/BC concentrations and optical properties. However, our understanding of metamorphism and changes in grain growth still has considerable range of uncertainty that, when passed through radiative transfer modeling, far exceeds in magnitude the at-surface greenhouse gas forcing of 3 W m-2. Likewise, it is a rare study that provides the quantitative knowledge of seasonal variation of dust and BC concentrations, let alone the range of optical properties. Therefore, the energy balance of snow in mountains around the globe is poorly understood and our capacity to model past, present, and future hydrologic responses is relatively weak. Atop the energy balance uncertainties, we also still do not know the spatio-temporal distributions of snow water equivalent in mountain basins around the globe. With the advent of the NASA Airborne Snow Observatory in 2013, we entered a new era of understanding mountain basin SWE. ASO uses scanning lidar, imaging spectrometer, and physical modeling to map distributions across basins in California, Colorado, and the Swiss Alps. The program is expanding in these and other regions for water management. However, in the science realm, in addition to providing the capacity to understand distributed SWE and its change, ASO is also pathfinding through the NASA Snow Experiment

The GLOBE Carbon Project: Integrating the Science of Carbon Cycling and Climate Change into K-12 Classrooms.

NASA Astrophysics Data System (ADS)

Ollinger, S. V.; Silverberg, S.; Albrechtova, J.; Freuder, R.; Gengarelly, L.; Martin, M.; Randolph, G.; Schloss, A.

2007-12-01

The global carbon cycle is a key regulator of the Earth's climate and is central to the normal function of ecological systems. Because rising atmospheric CO2 is the principal cause of climate change, understanding how ecosystems cycle and store carbon has become an extremely important issue. In recent years, the growing importance of the carbon cycle has brought it to the forefront of both science and environmental policy. The need for better scientific understanding has led to establishment of numerous research programs, such as the North American Carbon Program (NACP), which seeks to understand controls on carbon cycling under present and future conditions. Parallel efforts are greatly needed to integrate state-of-the-art science on the carbon cycle and its importance to climate with education and outreach efforts that help prepare society to make sound decisions on energy use, carbon management and climate change adaptation. Here, we present a new effort that joins carbon cycle scientists with the International GLOBE Education program to develop carbon cycle activities for K-12 classrooms. The GLOBE Carbon Cycle project is focused on bringing cutting edge research and research techniques in the field of terrestrial ecosystem carbon cycling into the classroom. Students will collect data about their school field site through existing protocols of phenology, land cover and soils as well as new protocols focused on leaf traits, and ecosystem growth and change. They will also participate in classroom activities to understand carbon cycling in terrestrial ecosystems, these will include plant- a-plant experiments, hands-on demonstrations of various concepts, and analysis of collected data. In addition to the traditional GLOBE experience, students will have the opportunity to integrate their data with emerging and expanding technologies including global and local carbon cycle models and remote sensing toolkits. This program design will allow students to explore research

Characterization of trabecular bone using the backscattered spectral centroid shift.

PubMed

Wear, Keith A

2003-04-01

Ultrasonic attenuation in bone in vivo is generally measured using a through-transmission method at the calcaneus. Although attenuation in calcaneus has been demonstrated to be a useful predictor for osteoporotic fracture risk, measurements at other clinically important sites, such as hip and spine, could potentially contain additional useful diagnostic information. Through-transmission measurements may not be feasible at these sites due to complex bone shapes and the increased amount of intervening soft tissue. Centroid shift from the backscattered signal is an index of attenuation slope and has been used previously to characterize soft tissues. In this paper, centroid shift from signals backscattered from 30 trabecular bone samples in vitro were measured. Attenuation slope also was measured using a through-transmission method. The correlation coefficient between centroid shift and attenuation slope was -0.71. The 95% confidence interval was (-0.86, -0.47). These results suggest that the backscattered spectral centroid shift may contain useful diagnostic information potentially applicable to hip and spine.

GLOBE at Night: Raising Public Awareness and Involvement through Citizen Science

NASA Astrophysics Data System (ADS)

Walker, C. E.; Pompea, S. M.; Sparks, R. T.

2010-12-01

With half of the world’s population now living in cities, many urban dwellers have never experienced the wonderment of pristinely dark skies and maybe never will. Light pollution is obscuring people’s long-standing natural heritage to view stars. The GLOBE at Night program (www.globeatnight.org) is an international citizen-science campaign to raise public awareness of the impact of light pollution by encouraging everyone everywhere to measure local levels of night sky brightness and contribute observations online to a world map. In the last 5 years, GLOBE at Night has been the most productive public light pollution monitoring campaign, collecting over 52,000 observations in a two-week period annually. This year, during the moonless two weeks in March, the campaign set a record high of over 17,800 measurements from people in 86 countries. Foundational resources are available to facilitate the public’s participation in promoting dark skies awareness. The GLOBE at Night website explains clearly the simple-to-participate-in 5 step program and offers background information and interactive games on key concepts. The program has been expanded to include trainings of the general public, but especially educators in schools, museums and science centers, in unique ways. Education kits for dark skies awareness have been distributed at the training workshops. The kit includes material for a light shielding demonstration, a digital Sky Quality Meter and “Dark Skies Rangers” activities. The activities are on how unshielded light wastes energy, how light pollution affects wildlife and how you can participate in a citizen-science star-hunt like GLOBE at Night. In addition, projects are being developed for what to do with the data once it is taken. The GLOBE at Night data from different years can be compared to look for trends over time or with population density maps. The data can also be used to search for dark sky oases or to monitor lighting ordinance compliance. Most

Recommendations for processing atmospheric attenuated backscatter profiles from Vaisala CL31 ceilometers

NASA Astrophysics Data System (ADS)

Kotthaus, Simone; O'Connor, Ewan; Münkel, Christoph; Charlton-Perez, Cristina; Haeffelin, Martial; Gabey, Andrew M.; Grimmond, C. Sue B.

2016-08-01

Ceilometer lidars are used for cloud base height detection, to probe aerosol layers in the atmosphere (e.g. detection of elevated layers of Saharan dust or volcanic ash), and to examine boundary layer dynamics. Sensor optics and acquisition algorithms can strongly influence the observed attenuated backscatter profiles; therefore, physical interpretation of the profiles requires careful application of corrections. This study addresses the widely deployed Vaisala CL31 ceilometer. Attenuated backscatter profiles are studied to evaluate the impact of both the hardware generation and firmware version. In response to this work and discussion within the CL31/TOPROF user community (TOPROF, European COST Action aiming to harmonise ground-based remote sensing networks across Europe), Vaisala released new firmware (versions 1.72 and 2.03) for the CL31 sensors. These firmware versions are tested against previous versions, showing that several artificial features introduced by the data processing have been removed. Hence, it is recommended to use this recent firmware for analysing attenuated backscatter profiles. To allow for consistent processing of historic data, correction procedures have been developed that account for artefacts detected in data collected with older firmware. Furthermore, a procedure is proposed to determine and account for the instrument-related background signal from electronic and optical components. This is necessary for using attenuated backscatter observations from any CL31 ceilometer. Recommendations are made for the processing of attenuated backscatter observed with Vaisala CL31 sensors, including the estimation of noise which is not provided in the standard CL31 output. After taking these aspects into account, attenuated backscatter profiles from Vaisala CL31 ceilometers are considered capable of providing valuable information for a range of applications including atmospheric boundary layer studies, detection of elevated aerosol layers, and model

An Arduino Based Citizen Science Soil Moisture Sensor in Support of SMAP and GLOBE

NASA Astrophysics Data System (ADS)

Podest, E.; Das, N. N.; Rajasekaran, E.; Jeyaram, R.; Lohrli, C.; Hovhannesian, H.; Fairbanks, G.

2017-12-01

Citizen science allows individuals anywhere in the world to engage in science by collecting environmental variables. One of the longest running platforms for the collection of in situ variables is the GLOBE program, which is international in scope and encourages students and citizen scientists alike to collect in situ measurements. NASA's Soil Moisture Active Passive (SMAP) satellite mission, which has been acquiring global soil moisture measurements every 3 days of the top 5 cm of the soil since 2015, has partnered with the GLOBE program to engage students from around the world to collect in situ soil moisture and help validate SMAP measurements. The current GLOBE SMAP soil moisture protocol consists in collecting a soil sample, weighing, drying and weighing it again in order to determine the amount of water in the soil. Preparation and soil sample collection can take up to 20 minutes and drying can take up to 3 days. We have hence developed a soil moisture measurement device based on Arduino- microcontrollers along with off-the-shelf and homemade sensors that are accurate, robust, inexpensive and quick and easy to use so that they can be implemented by the GLOBE community and citizen scientists alike. In addition, we have developed a phone app, which interfaces with the Arduino, displays the soil moisture value and send the measurement to the GLOBE database. This talk will discuss building, calibration and validation of the soil moisture measuring device and assessing the quality of the measurements collected. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Profiling of back-scattered electrons in opposed magnetic field of a Twin Electron Beam Gun

NASA Astrophysics Data System (ADS)

Sethi, S.; Gupta, Anchal; Dileep Kumar, V.; Mukherjee, Jaya; Gantayet, L. M.

2012-11-01

Electron gun is extensively used in material processing, physical vapour deposition and atomic vapour based laser processes. In these processes where the electron beam is incident on the substrate, a significant fraction of electron beam gets back-scattered from the target surface. The trajectory of this back scattered electron beam depends on the magnetic field in the vicinity. The fraction of back-scattered depends on the atomic number of the target metal and can be as high as ~40% of the incident beam current. These back-scattered electrons can cause undesired hot spots and also affect the overall process. Hence, the study of the trajectory of these back-scattered electrons is important. This paper provides the details of experimentally mapped back-scattered electrons of a 2×20kW Twin Electron Beam Gun (TEBG) in opposed magnetic field i.e. with these guns placed at 180° to each other.

Assessing Performance of P-Band Backscattering Coefficients and TSAR in Hemi-Boreal Forest AGB Estimation

NASA Astrophysics Data System (ADS)

Li, Wenmei; Chen, Erxue; Li, Zengyuan; Feng, Qi

2014-11-01

To assess performance of P-band backscattering coefficients and TSAR for hemi-boreal forest AGB estimation, airborne P-band repeat-path Pol-InSAR data collected by ESAR in Ramingstorp test site during March and May 2007 are applied. The correlation coefficient (R) between P-band backscattering coefficients and in-situ biomass reaches 0.87 for HH polarization. Meanwhile, the R between P-band backscattering power at specific height and in-situ biomass are higher in VV polarization than that in HH and HV polarization. And R between P-band backscattering power and in-situ biomass reaches 0.70 at 5m and 10m height in VV polarization.

Assessing Performance of P-Band Backscattering Coefficients and TSAR in Hemi-Boreal Forest AGB Estimation

NASA Astrophysics Data System (ADS)

Li, Wenmei; Chen, Erxue; Li, Zengyuan; Feng, Qi

2014-11-01

To assess performance of P-band backscattering coefficients and TSAR for hemi-boreal forest AGB estimation, airborne P-band repeat-path Pol-InSAR data collected by ESAR in Ramingstorp test site during March and May 2007 are applied.The correlation coefficient (R) between P-band backscattering coefficients and in-situ biomass reaches 0.87 for HH polarization. Meanwhile, the R between P-band backscattering power at specific height and in-situ biomass are higher in VV polarization than that in HH and HV polarization. And R between P-band backscattering power and in-situ biomass reaches 0.70 at 5m and 10m height in VV polarization.

Evaluation of backscatter dose from internal lead shielding in clinical electron beams using EGSnrc Monte Carlo simulations.

PubMed

De Vries, Rowen J; Marsh, Steven

2015-11-08

Internal lead shielding is utilized during superficial electron beam treatments of the head and neck, such as lip carcinoma. Methods for predicting backscattered dose include the use of empirical equations or performing physical measurements. The accuracy of these empirical equations required verification for the local electron beams. In this study, a Monte Carlo model of a Siemens Artiste linac was developed for 6, 9, 12, and 15 MeV electron beams using the EGSnrc MC package. The model was verified against physical measurements to an accuracy of better than 2% and 2mm. Multiple MC simulations of lead interfaces at different depths, corresponding to mean electron energies in the range of 0.2-14 MeV at the interfaces, were performed to calculate electron backscatter values. The simulated electron backscatter was compared with current empirical equations to ascertain their accuracy. The major finding was that the current set of backscatter equations does not accurately predict electron backscatter, particularly in the lower energies region. A new equation was derived which enables estimation of electron backscatter factor at any depth upstream from the interface for the local treatment machines. The derived equation agreed to within 1.5% of the MC simulated electron backscatter at the lead interface and upstream positions. Verification of the equation was performed by comparing to measurements of the electron backscatter factor using Gafchromic EBT2 film. These results show a mean value of 0.997 ± 0.022 to 1σ of the predicted values of electron backscatter. The new empirical equation presented can accurately estimate electron backscatter factor from lead shielding in the range of 0.2 to 14 MeV for the local linacs.

Waterfall notch-filtering for restoration of acoustic backscatter records from Admiralty Bay, Antarctica

NASA Astrophysics Data System (ADS)

Fonseca, Luciano; Hung, Edson Mintsu; Neto, Arthur Ayres; Magrani, Fábio José Guedes

2018-06-01

A series of multibeam sonar surveys were conducted from 2009 to 2013 around Admiralty Bay, Shetland Islands, Antarctica. These surveys provided a detailed bathymetric model that helped understand and characterize the bottom geology of this remote area. Unfortunately, the acoustic backscatter records registered during these bathymetric surveys were heavily contaminated with noise and motion artifacts. These artifacts persisted in the backscatter records despite the fact that the proper acquisition geometry and the necessary offsets and delays were applied during the survey and in post-processing. These noisy backscatter records were very difficult to interpret and to correlate with gravity-core samples acquired in the same area. In order to address this issue, a directional notch-filter was applied to the backscatter waterfall in the along-track direction. The proposed filter provided better estimates for the backscatter strength of each sample by considerably reducing residual motion artifacts. The restoration of individual samples was possible since the waterfall frame of reference preserves the acquisition geometry. Then, a remote seafloor characterization procedure based on an acoustic model inversion was applied to the restored backscatter samples, generating remote estimates of acoustic impedance. These remote estimates were compared to Multi Sensor Core Logger measurements of acoustic impedance obtained from gravity core samples. The remote estimates and the Core Logger measurements of acoustic impedance were comparable when the shallow seafloor was homogeneous. The proposed waterfall notch-filtering approach can be applied to any sonar record, provided that we know the system ping-rate and sampling frequency.

Optical-beam wavefront control based on the atmospheric backscatter signal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banakh, V A; Razenkov, I A; Rostov, A P

2015-02-28

The feasibility of compensating for aberrations of the optical-beam initial wavefront by aperture sounding, based on the atmospheric backscatter signal from an additional laser source with a different wavelength, is experimentally studied. It is shown that the adaptive system based on this principle makes it possible to compensate for distortions of the initial beam wavefront on a surface path in atmosphere. Specifically, the beam divergence decreases, while the level of the detected mean backscatter power from the additional laser source increases. (light scattering)

The Globe. Neighbourhood Agenda 21: Going Local in Reading.

ERIC Educational Resources Information Center

Welsh, Richard

1994-01-01

Reports on the philosophy underlying a project to promote local community involvement in neighborhood plans as a basis for a citywide Local Agenda 21 and the first stages of Go Local on a Better Environment (GLOBE) introduced to give the project a popular identify and communicate the environmental message. (LZ)

(abstract) Variations in Polarimetric Backscatter of Saline Ice Grown Under Diurnal Thermal Cycling Condition

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Kong, J. A.; Hsu, C. C.; Ding, K. H.

1995-01-01

An experiment was carried out in January 1994 at the Geophysical Research Facility in the Cold Regions Research and Engineering Laboratory. To investigate effects on polarimetric scattering signatures of sea ice growth under diurnal temperature variations, an ice sheet was grown for 2.5 days for the thickness of 10 cm and a polarimetric radar operating at C-band was used to obtain backscattering data in conjunction with ice-characterization measurements. The ice sheet was grown in the late morning of January 19, 1994. The initial growth rate was slow due to high insolation and temperature. As the air temperature dropped during the night, the growth rate increased significantly. The air temperature changed drastically from about -10(deg)C to -35(deg)C between day and night. The temperature cycle was repeated during the next day and the growth rate varied in the same manner. The surface of the ice was partially covered by frost flowers and the areal coverage increased as the ice became thicker. Throughout the ice growth duration of 2.5 days, polarimetric backscatter data were collected at roughly every centimeter of ice growth. For each set of radar measurements of saline ice, a set of calibration measurements was carried out with trihedrial corner reflectors and a metallic sphere. Measured polarimetric backscattering coefficients of the ice sheet reveal a strong correlation between radar data and temperature variations. As the temperature increased (decreased), the backscatter increased (decreased) correspondingly. From the ice-characterization data, temperatures of the air, at the ice-air interface, and in the ice layer had the same variation trend. Another interesting experimental observation is that the salinity measured as a function of ice depth from a sample of 10-cm thich ice indicated that the salinity variations had a similar cycle as the temperature; i.e., the salinity profile recorded the history of the temperature variations. Characterization data of the

Multi-angle backscatter classification and sub-bottom profiling for improved seafloor characterization

NASA Astrophysics Data System (ADS)

Alevizos, Evangelos; Snellen, Mirjam; Simons, Dick; Siemes, Kerstin; Greinert, Jens

2018-06-01

This study applies three classification methods exploiting the angular dependence of acoustic seafloor backscatter along with high resolution sub-bottom profiling for seafloor sediment characterization in the Eckernförde Bay, Baltic Sea Germany. This area is well suited for acoustic backscatter studies due to its shallowness, its smooth bathymetry and the presence of a wide range of sediment types. Backscatter data were acquired using a Seabeam1180 (180 kHz) multibeam echosounder and sub-bottom profiler data were recorded using a SES-2000 parametric sonar transmitting 6 and 12 kHz. The high density of seafloor soundings allowed extracting backscatter layers for five beam angles over a large part of the surveyed area. A Bayesian probability method was employed for sediment classification based on the backscatter variability at a single incidence angle, whereas Maximum Likelihood Classification (MLC) and Principal Components Analysis (PCA) were applied to the multi-angle layers. The Bayesian approach was used for identifying the optimum number of acoustic classes because cluster validation is carried out prior to class assignment and class outputs are ordinal categorical values. The method is based on the principle that backscatter values from a single incidence angle express a normal distribution for a particular sediment type. The resulting Bayesian classes were well correlated to median grain sizes and the percentage of coarse material. The MLC method uses angular response information from five layers of training areas extracted from the Bayesian classification map. The subsequent PCA analysis is based on the transformation of these five layers into two principal components that comprise most of the data variability. These principal components were clustered in five classes after running an external cluster validation test. In general both methods MLC and PCA, separated the various sediment types effectively, showing good agreement (kappa >0.7) with the Bayesian

A Model for Backscattering from Quasi Periodic Corn Canopies at L-Band

NASA Technical Reports Server (NTRS)

Lang, R.; Utku, C.; Zhao, Q.; O'Neill, P.

2010-01-01

In this study, a model for backscattering at L-band from a corn canopy is proposed. The canopy consists of a quasi-periodic distribution of stalks and a random distribution of leaves. The Distorted Born Approximation (DBA) is employed to calculate the single scattered return from the corn field. The new feature of the method is that the coherence of the stalks in the row direction is incorporated in the model in a systematic fashion. Since the wavelength is on the order of the distance between corn stalks in a row, grating lobe behavior is observed at certain azimuth angles of incidence. The results are compared with experimental values measured in Huntsville, Alabama in 1998. The mean field and the effective dielectric constant of the canopy are obtained by using the Foldy approximation. The stalks are placed in the effective medium in a two dimensional lattice to simulate the row structure of a corn field. In order to mimic a real corn field, a quasi-periodic stalk distribution is assumed where the stalks are given small random perturbations about their lattice locations. Corn leaves are also embedded in the effective medium and the backscattered field from the stalks and the leaves is computed. The backscattering coefficient is calculated and averaged over successive stalk position perturbations. It is assumed that soil erosion has smoothed the soil sufficiently so that it can be assumed flat. Corn field backscatter data was collected from cornfields during the Huntsville 98 experimental campaign held at Alabama A&M University Research Station, Huntsville, Alabama in 1998 using the NASA/GW truck mounted radar. Extensive ground truth data was collected. This included soil moisture measurements and corn plant architectural data to be used in the model. In particular, the distances between the stalks in a single row have been measured. The L-band radar backscatter data was collected for both H and V polarizations and for look angles of 15o and 45o over a two week

Backscatter nephelometer to calibrate scanning lidar

Treesearch

Cyle E. Wold; Vladmir A. Kovalev; Wei Min Hao

2008-01-01

The general concept of an open-path backscatter nephelometer, its design, principles of calibration and the operational use are discussed. The research-grade instrument, which operates at the wavelength 355 nm, will be co-located with a scanning-lidar at measurement sites near wildfires, and used for the lidar calibration. Such a near-end calibration has significant...

Skin dose mapping for non-uniform x-ray fields using a backscatter point spread function

NASA Astrophysics Data System (ADS)

Vijayan, Sarath; Xiong, Zhenyu; Shankar, Alok; Rudin, Stephen; Bednarek, Daniel R.

2017-03-01

Beam shaping devices like ROI attenuators and compensation filters modulate the intensity distribution of the xray beam incident on the patient. This results in a spatial variation of skin dose due to the variation of primary radiation and also a variation in backscattered radiation from the patient. To determine the backscatter component, backscatter point spread functions (PSF) are generated using EGS Monte-Carlo software. For this study, PSF's were determined by simulating a 1 mm beam incident on the lateral surface of an anthropomorphic head phantom and a 20 cm thick PMMA block phantom. The backscatter PSF's for the head phantom and PMMA phantom are curve fit with a Lorentzian function after being normalized to the primary dose intensity (PSFn). PSFn is convolved with the primary dose distribution to generate the scatter dose distribution, which is added to the primary to obtain the total dose distribution. The backscatter convolution technique is incorporated in the dose tracking system (DTS), which tracks skin dose during fluoroscopic procedures and provides a color map of the dose distribution on a 3D patient graphic model. A convolution technique is developed for the backscatter dose determination for the nonuniformly spaced graphic-model surface vertices. A Gafchromic film validation was performed for shaped x-ray beams generated with an ROI attenuator and with two compensation filters inserted into the field. The total dose distribution calculated by the backscatter convolution technique closely agreed with that measured with the film.

Effect of curvature on the backscattering from a leaf

NASA Technical Reports Server (NTRS)

Sarabandi, K.; Senior, T. B. A.; Ulaby, F. T.

1988-01-01

Using a model previously developed for the backscattering cross section of a planar leaf at X-band frequencies and above, the effect of leaf curvature is examined. For normal incidence on a rectangular section of a leaf curved in one and two dimensions, an integral expression for the backscattered field is evaluated numerically and by a stationary phase approximation, leading to a simple analytical expression for the cross-section reduction produced by the curvature. Numerical results based on the two methods are virtually identical, and in excellent agreement with measured data for rectangular sections of coleus leaves applied to the surfaces of styrofoam cylinders and spheres of different radii.

Backscattering of decametric waves on magnetically oriented ionosphere inhomogeneities

NASA Astrophysics Data System (ADS)

Sivokon', V. P.

2017-05-01

The method of study of magnetically oriented ionosphere inhomogeneities based on the analysis of radar decametric emission backscattering on inhomogeneities is proposed. It is shown that certain conditions, including the orientation of the propagation route relative to the Earth's magnetic field lines and the polarization and frequency of the emitted wave, make possible resonant backscattering of radiolocation system emission on magnetically oriented ionosphere inhomogeneities. The paper presents the results of experimental observation of scattering in Kamchatka Peninsula. They demonstrated the opportunity to evaluate the extension of the scattering region, the vertical and horizontal components of the velocities of magnetically oriented inhomogeneities, and the frequency dependence of these parameters.

NASA Webworldwind: Multidimensional Virtual Globe for Geo Big Data Visualization

NASA Astrophysics Data System (ADS)

Brovelli, M. A.; Hogan, P.; Prestifilippo, G.; Zamboni, G.

2016-06-01

In this paper, we presented a web application created using the NASA WebWorldWind framework. The application is capable of visualizing n-dimensional data using a Voxel model. In this case study, we handled social media data and Call Detailed Records (CDR) of telecommunication networks. These were retrieved from the "BigData Challenge 2015" of Telecom Italia. We focused on the visualization process for a suitable way to show this geo-data in a 3D environment, incorporating more than three dimensions. This engenders an interactive way to browse the data in their real context and understand them quickly. Users will be able to handle several varieties of data, import their dataset using a particular data structure, and then mash them up in the WebWorldWind virtual globe. A broad range of public use this tool for diverse purposes is possible, without much experience in the field, thanks to the intuitive user-interface of this web app.

Computation of Nonlinear Backscattering Using a High-Order Numerical Method

NASA Technical Reports Server (NTRS)

Fibich, G.; Ilan, B.; Tsynkov, S.

2001-01-01

The nonlinear Schrodinger equation (NLS) is the standard model for propagation of intense laser beams in Kerr media. The NLS is derived from the nonlinear Helmholtz equation (NLH) by employing the paraxial approximation and neglecting the backscattered waves. In this study we use a fourth-order finite-difference method supplemented by special two-way artificial boundary conditions (ABCs) to solve the NLH as a boundary value problem. Our numerical methodology allows for a direct comparison of the NLH and NLS models and for an accurate quantitative assessment of the backscattered signal.

Target reflectance measurements for calibration of lidar atmospheric backscatter data

NASA Technical Reports Server (NTRS)

Kavaya, M. J.; Menzies, R. T.; Haner, D. A.; Oppenheim, U. P.; Flamant, P. H.

1983-01-01

Wavelength and angular dependence of reflectances and depolarization in the 9-11 micron region are reported for four standard targets: flowers of sulfur, flame-sprayed aluminum, 20-grit sandblasted aluminum, and 400-grit silicon carbon sandpaper. Measurements are presented and compared using a CW CO2 grating-tunable laser in a laboratory backscatter apparatus, an integrating sphere, and a coherent pulsed TEA-CO2 lidar system operating in the 9-11 micron region. Reflectance theory related to the use of hard targets to calibrate lidar atmospheric backscatter data is discussed.

Evaluation of backscatter dose from internal lead shielding in clinical electron beams using EGSnrc Monte Carlo simulations

PubMed Central

Marsh, Steven

2015-01-01

Internal lead shielding is utilized during superficial electron beam treatments of the head and neck, such as lip carcinoma. Methods for predicting backscattered dose include the use of empirical equations or performing physical measurements. The accuracy of these empirical equations required verification for the local electron beams. In this study, a Monte Carlo model of a Siemens Artiste linac was developed for 6, 9, 12, and 15 MeV electron beams using the EGSnrc MC package. The model was verified against physical measurements to an accuracy of better than 2% and 2 mm. Multiple MC simulations of lead interfaces at different depths, corresponding to mean electron energies in the range of 0.2–14 MeV at the interfaces, were performed to calculate electron backscatter values. The simulated electron backscatter was compared with current empirical equations to ascertain their accuracy. The major finding was that the current set of backscatter equations does not accurately predict electron backscatter, particularly in the lower energies region. A new equation was derived which enables estimation of electron backscatter factor at any depth upstream from the interface for the local treatment machines. The derived equation agreed to within 1.5% of the MC simulated electron backscatter at the lead interface and upstream positions. Verification of the equation was performed by comparing to measurements of the electron backscatter factor using Gafchromic EBT2 film. These results show a mean value of 0.997±0.022 to 1σ of the predicted values of electron backscatter. The new empirical equation presented can accurately estimate electron backscatter factor from lead shielding in the range of 0.2 to 14 MeV for the local linacs. PACS numbers: 87.53.Bn, 87.55.K‐, 87.56.bd PMID:26699566

Simulation of Radar-Backscattering from Phobos - A Contribution to the Experiment MARSIS aboard MarsExpress

NASA Astrophysics Data System (ADS)

Plettemeier, D.; Hahnel, R.; Hegler, S.; Safaeinili, A.; Orosei, R.; Cicchetti, A.; Plaut, J.; Picardi, G.

2009-04-01

MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) on board MarsExpress is the first and so far the only space borne radar that observed the Martian moon Phobos. Radar echoes were measured for different flyby trajectories. The primary aim of the low frequency sounding of Phobos is to prove the feasibility of deep sounding, into the crust of Phobos. In this poster we present a numerical method that allows a very precise computation of radar echoes backscattered from the surface of large objects. The software is based on a combination of physical optics calculation of surface scattering of the radar target, and Method of Moments to calculate the radiation pattern of the whole space borne radar system. The calculation of the frequency dependent radiation pattern takes into account all relevant gain variations and coupling effects aboard the space craft. Based on very precise digital elevation models of Phobos, patch models in the resolution of lambda/10 were generated. Simulation techniques will be explained and a comparison of simulations and measurements will be shown. SURFACE BACKSCATTERING SIMULATOR FOR LARGE OBJECTS The computation of surface scattering of the electromagnetic wave incident on Phobos is based on the Physical Optics method. The scattered field can be expressed by the induced equivalent surface currents on the target. The Algorithm: The simulation program itself is split into three phases. In the first phase, an illumination test checks whether a patch will be visible from the position of the space craft. If this is not the case, the patch will be excluded from the simulation. The second phase serves as a preparation stage for the third phase. Amongst other tasks, the dyadic products for the Js and Ms surface currents are calculated. This is a time-memory trade-off: the simulation will need additional 144 bytes of RAM for every patch that passes phase one. However, the calculation of the dyads is expensive, so that considerable

Wavelength dependence of aerosol backscatter coefficients obtained by multiple wavelength Lidar measurements

NASA Technical Reports Server (NTRS)

Sasano, Y.; Browell, E. V.

1986-01-01

Aerosols are often classified into several general types according to their origins and composition, such as maritime, continental, and stratospheric aerosols, and these aerosol types generally have different characteristics in chemical and physical properties. The present study aims at demonstrating the potential for distinguishing these aerosol types by the wavelength dependence of their backscatter coefficients obtained from quantitative analyses of multiple wavelength lidar signals. Data from the NASA Airborne Differential Abosrption lidar (DIAL) S ystems, which can measure aerosol backscatter profiles at wavelenghts of 300, 600, and 1064 nm and ozone profiles of backscatter coefficients for these three wavelength were derived from the observations of aerosols of different types. Observations were performed over the Atlantic Ocean, the Southwestern United States, and French Guyana.

Experimental evaluation of effective atomic number of composite materials using back-scattering of gamma photons

NASA Astrophysics Data System (ADS)

Singh, Inderjeet; Singh, Bhajan; Sandhu, B. S.; Sabharwal, Arvind D.

2017-04-01

A method has been presented for calculation of effective atomic number (Zeff) of composite materials, by using back-scattering of 662 keV gamma photons obtained from a 137Cs mono-energetic radioactive source. The present technique is a non-destructive approach, and is employed to evaluate Zeff of different composite materials, by interacting gamma photons with semi-infinite material in a back-scattering geometry, using a 3″ × 3″ NaI(Tl) scintillation detector. The present work is undertaken to study the effect of target thickness on intensity distribution of gamma photons which are multiply back-scattered from targets (pure elements) and composites (mixtures of different elements). The intensity of multiply back-scattered events increases with increasing target thickness and finally saturates. The saturation thickness for multiply back-scattered events is used to assign a number (Zeff) for multi-element materials. Response function of the 3″ × 3″ NaI(Tl) scintillation detector is applied on observed pulse-height distribution to include the contribution of partially absorbed photons. The reduced value of signal-to-noise ratio interprets the increase in multiply back-scattered data of a response corrected spectrum. Data obtained from Monte Carlo simulations and literature also support the present experimental results.

Multi-procedure management in an eyeglasses-related open globe injury

PubMed Central

Skopiński, Piotr; Langwińska-Wośko, Ewa; Korwin, Magdalena; Kołodziejczyk, Wojciech; Ambroziak, Anna Maria

2014-01-01

We present a case of successful multi-procedure management of a patient with an open globe injury. A 47-year-old man sustained an injury to his left eye caused by glass fragments of his own spectacles shattered while he was protecting an unknown woman from physical assault at a bus stop. Over a span of 65 months the patient underwent multiple procedures including primary wound repair, penetrating keratoplasty combined with extracapsular cataract extraction, neodymium: YAG laser capsulotomy, and laser-assisted subepithelial keratectomy (LASEK), and had a successfully treated episode of corneal graft rejection. This sequence of treatment substantially improved his left eye vision from hand movements at the time of admission to 0.9–0.5 × 90 at the last follow-up nearly 10 years after the trauma. Proper initial surgical management of an open globe injury can create the possibility for virtually complete vision restoration. PMID:24729818

Microbial cultures in open globe injuries in southern India.

PubMed

Gupta, Arvind; Srinivasan, Renuka; Kaliaperumal, Subashini; Setia, Sajita

2007-07-01

To determine the risk factors leading to positive intraocular culture in patients with open globe injury. A prospective interventional study involving 110 eyes of 110 patients of more than 15 years of age, presenting with open globe injury, was undertaken. Emergency repair of the injured globe was done. Prolapsed intraocular tissue or aqueous humour was sent for microbial work up before repair. In endophthalmitis cases intravitreal antibiotics were given according to the antimicrobial sensitivity. Chi-square and logistic regression analysis were used to determine the risk factors. Fifty-six patients showed microbial contamination. Bacteria were cultured in 42 patients and fungi in 14 patients. Nineteen patients developed endophthalmitis, of which 18 patients showed microbial growth initially. In univariate analysis, initial visual acuity (<6/360, P = 0.002), presence of uveal tissue prolapse (P < 0.001), vitreous prolapse (P < 0.001) and length of laceration (>8 mm, P < 0.001) were significantly associated with positive microbial culture, however, in the multivariate stepwise logistic regression delay in surgical intervention (>72 h, P < 0.001), uveal tissue prolapse (P = 0.004) and corneosclearal laceration (>8 mm, P = 0.013) were associated with increased risk of positive microbial culture. Six patients had intraocular foreign body but were culture negative. Age, gender, site of injury and presence of cataract did not significantly affect the culture positivity. Microbial contamination is a risk factor for the development for endophthalmitis. Despite the high frequency of microbial contamination, it develops only in few cases. Systemic antibiotics, virulence of the organism and host factors play a role in the manifestation of endophthalmitis. Prophylaxis with intraocular antibiotics should be strongly considered in cases with poor vision at presentation, larger corneoscleral laceration, delayed surgical intervention and uveal tissue or vitreous prolapse.

Window flaw detection by backscatter lighting

NASA Technical Reports Server (NTRS)

Crockett, L. K.; Minton, F. R.

1978-01-01

Portable fiber-optic probe detects tiny flaws in transparent materials. Probe transmits light through surface to illuminate interior of material by backscattering off its edges. Light-sensitive contact paper records scratch pattern. Technique can be used for rapid visual checks. Flexible fiber optics are safely used in explosive or flammable areas; they present no hazard of breakage or contamination in controlled environments.

Backscattering of electrons from solid targets

NASA Astrophysics Data System (ADS)

Dapor, Maurizio

1990-11-01

A simple equation is derived which describes the electron backscattering coefficient as a function of the target atomic number in the primary energy range 2-45 KeV. Such an equation, very useful for practical purposes, is in better agreement with the experimental data of Palluel and of Cosslett and Thomas than both the treatments of Everhart and of Archard.

Spectra of Particulate Backscattering in Natural Waters

NASA Technical Reports Server (NTRS)

Gordon, Howard, R.; Lewis, Marlon R.; McLean, Scott D.; Twardowski, Michael S.; Freeman, Scott A.; Voss, Kenneth J.; Boynton, Chris G.

2009-01-01

Hyperspectral profiles of downwelling irradiance and upwelling radiance in natural waters (oligotrophic and mesotrophic) are combined with inverse radiative transfer to obtain high resolution spectra of the absorption coefficient (a) and the backscattering coefficient (bb) of the water and its constituents. The absorption coefficient at the mesotrophic station clearly shows spectral absorption features attributable to several phytoplankton pigments (Chlorophyll a, b, c, and Carotenoids). The backscattering shows only weak spectral features and can be well represented by a power-law variation with wavelength (lambda): b(sub b) approx. Lambda(sup -n), where n is a constant between 0.4 and 1.0. However, the weak spectral features in b(sub b), suggest that it is depressed in spectral regions of strong particle absorption. The applicability of the present inverse radiative transfer algorithm, which omits the influence of Raman scattering, is limited to lambda < 490 nm in oligotrophic waters and lambda < 575 nm in mesotrophic waters.

Terrain-analysis procedures for modeling radar backscatter

USGS Publications Warehouse

Schaber, Gerald G.; Pike, Richard J.; Berlin, Graydon Lennis

1978-01-01

The collection and analysis of detailed information on the surface of natural terrain are important aspects of radar-backscattering modeling. Radar is especially sensitive to surface-relief changes in the millimeter- to-decimeter scale four conventional K-band (~1-cm wavelength) to L-band (~25-cm wavelength) radar systems. Surface roughness statistics that characterize these changes in detail have been generated by a comprehensive set of seven programmed calculations for radar-backscatter modeling from sets of field measurements. The seven programs are 1) formatting of data in readable form for subsequent topographic analysis program; 2) relief analysis; 3) power spectral analysis; 4) power spectrum plots; 5) slope angle between slope reversals; 6) slope angle against slope interval plots; and 7) base length slope angle and curvature. This complete Fortran IV software package, 'Terrain Analysis', is here presented for the first time. It was originally developed a decade ago for investigations of lunar morphology and surface trafficability for the Apollo Lunar Roving Vehicle.

Novel X-ray backscatter technique for detection of dangerous materials: application to aviation and port security

NASA Astrophysics Data System (ADS)

Kolkoori, S.; Wrobel, N.; Osterloh, K.; Zscherpel, U.; Ewert, U.

2013-09-01

Radiological inspections, in general, are the nondestructive testing (NDT) methods to detect the bulk of explosives in large objects. In contrast to personal luggage, cargo or building components constitute a complexity that may significantly hinder the detection of a threat by conventional X-ray transmission radiography. In this article, a novel X-ray backscatter technique is presented for detecting suspicious objects in a densely packed large object with only a single sided access. It consists of an X-ray backscatter camera with a special twisted slit collimator for imaging backscattering objects. The new X-ray backscatter camera is not only imaging the objects based on their densities but also by including the influences of surrounding objects. This unique feature of the X-ray backscatter camera provides new insights in identifying the internal features of the inspected object. Experimental mock-ups were designed imitating containers with threats among a complex packing as they may be encountered in reality. We investigated the dependence of the quality of the X-ray backscatter image on (a) the exposure time, (b) multiple exposures, (c) the distance between object and slit camera, and (d) the width of the slit. At the end, the significant advantages of the presented X-ray backscatter camera in the context of aviation and port security are discussed.

Visualization and dissemination of global crustal models on virtual globes

NASA Astrophysics Data System (ADS)

Zhu, Liang-feng; Pan, Xin; Sun, Jian-zhong

2016-05-01

Global crustal models, such as CRUST 5.1 and its descendants, are very useful in a broad range of geoscience applications. The current method for representing the existing global crustal models relies heavily on dedicated computer programs to read and work with those models. Therefore, it is not suited to visualize and disseminate global crustal information to non-geological users. This shortcoming is becoming obvious as more and more people from both academic and non-academic institutions are interested in understanding the structure and composition of the crust. There is a pressing need to provide a modern, universal and user-friendly method to represent and visualize the existing global crustal models. In this paper, we present a systematic framework to easily visualize and disseminate the global crustal structure on virtual globes. Based on crustal information exported from the existing global crustal models, we first create a variety of KML-formatted crustal models with different levels of detail (LODs). And then the KML-formatted models can be loaded into a virtual globe for 3D visualization and model dissemination. A Keyhole Markup Language (KML) generator (Crust2KML) is developed to automatically convert crustal information obtained from the CRUST 1.0 model into KML-formatted global crustal models, and a web application (VisualCrust) is designed to disseminate and visualize those models over the Internet. The presented framework and associated implementations can be conveniently exported to other applications to support visualizing and analyzing the Earth's internal structure on both regional and global scales in a 3D virtual-globe environment.

A Novel Three-Dimensional Vector Analysis of Axial Globe Position in Thyroid Eye Disease

PubMed Central

Guo, Jie; Yuan, Yifei; Zhang, Rui; Huang, Wenhu

2017-01-01

Purpose. To define a three-dimensional (3D) vector method to describe the axial globe position in thyroid eye disease (TED). Methods. CT data from 59 patients with TED were collected and 3D images were reconstructed. A reference coordinate system was established, and the coordinates of the corneal apex and the eyeball center were calculated to obtain the globe vector EC→. The measurement reliability was evaluated. The parameters of EC→ were analyzed and compared with the results of two-dimensional (2D) CT measurement, Hertel exophthalmometry, and strabismus tests. Results. The reliability of EC→ measurement was excellent. The difference between EC→ and 2D CT measurement was significant (p = 0.003), and EC→ was more consistent with Hertel exophthalmometry than with 2D CT measurement (p < 0.001). There was no significant difference between EC→ and Hirschberg test, and a strong correlation was found between EC→ and synoptophore test. When one eye had a larger deviation angle than its fellow, its corneal apex shifted in the corresponding direction, but the shift of the eyeball center was not significant. The parameters of EC→ were almost perfectly consistent with the geometrical equation. Conclusions. The establishment of a 3D globe vector is feasible and reliable, and it could provide more information in the axial globe position. PMID:28491471

Construction of a reference molecular linkage map of globe artichoke (Cynara cardunculus var. scolymus).

PubMed

Portis, E; Mauromicale, G; Mauro, R; Acquadro, A; Scaglione, D; Lanteri, S

2009-12-01

The genome organization of globe artichoke (Cynara cardunculus var. scolymus), unlike other species belonging to Asteraceae (=Compositae) family (i.e. sunflower, lettuce and chicory), remains largely unexplored. The species is highly heterozygous and suffers marked inbreeding depression when forced to self-fertilize. Thus a two-way pseudo-testcross represents the optimal strategy for linkage analysis. Here, we report linkage maps based on the progeny of a cross between globe artichoke (C. cardunculus var. scolymus) and cultivated cardoon (C. cardunculus var. altilis). The population was genotyped using a variety of PCR-based marker platforms, resulting in the identification of 708 testcross markers suitable for map construction. The male map consisted of 177 loci arranged in 17 major linkage groups, spanning 1,015.5 cM, while female map was built with 326 loci arranged into 20 major linkage groups, spanning 1,486.8 cM. The presence of 84 loci shared between these maps and those previously developed from a cross within globe artichoke allowed for map alignment and the definition of 17 homologous linkage groups, corresponding to the haploid number of the species. This will provide a favourable property for QTL scanning; furthermore, as 25 mapped markers (8%) correspond to coding regions, it has an additional value as functional map and might represent an important genetic tool for candidate gene studies in globe artichoke.

On the relationship between age of lava flows and radar backscattering

NASA Technical Reports Server (NTRS)

Blom, R. G.; Cooley, P.; Schenck, L. R.

1986-01-01

The observation that older lava flows have lower backscatter in radar images is assessed with multiwavelength/polarization scatterometer data with incidence angles from 15 to 50 deg. Backscatter decreases over time because surface roughness decreases due to infilling with dust and mechanical weathering of the rocks. Pahoehoe lavas in the Snake River Plain with ages of 2.1, 7,4, and 12.0 K yr are best separated with 2.25 cm wavelength data. Blocky obsidian flows at Medicine Lake Highland and Newberry Volcano with ages of 0.9, 1.1 and 1.4 K yr are best separated with 6.3 cm wavelength data. Two Pleistocene flows at the Snake River Plain are best separated with 19.0 cm wavelength data. Incidence angles from 20 to 35 deg are best. These data indicate it may be possible to separate lava flows into eruptive periods using calibrated multiwavelength radar backscatter data.

Switchable and non-switchable zero backscattering of dielectric nano-resonators

DOE PAGES

Wang, Feng; Wei, Qi -Huo; Htoon, Han

2015-02-27

Previous studies have shown that two-dimensional (2D) arrays of high-permittivity dielectric nanoparticles are capable of fully suppressing backward light scattering when the resonant frequencies of electrical and magnetic dipolar modes are coincident. In this paper, we numerically demonstrate that the zero-backscattering of 2D Si nanocuboid arrays can be engineered to be switchable or non-switchable in response to a variation in the environmental refractive index. For each cuboid width/length, there exist certain cuboid heights and orthogonal periodicity ratio for which the electrical and magnetic resonances exhibit similar spectra widths and equivalent sensitivities to the environmental index changes, so that the zero-backscatteringmore » is non-switchable upon environmental change. For some other cuboid heights and certain anisotropic periodicity ratios, the electric and magnetic modes exhibit different sensitivities to environmental index changes, making the zero-backscattering sensitive to environmental changes. We also show that by using two different types of nano-resonators in the unit cell, Fano resonances can be introduced to greatly enhance the switching sensitivity of zero-backscattering.« less

Backscatter-to-Extinction Ratios in the Top Layers of Tropical Mesoscale Convective Systems and in Isolated Cirrus from LITE Observations

NASA Technical Reports Server (NTRS)

Platt, C. M. R.; Winker, D. M.; Vaughan, M. A.; Miller, S. D.

1999-01-01

Cloud-integrated attenuated backscatter from observations with the Lidar In-Space Technology Experiment (LITE) was studied over a range of cirrus clouds capping some extensive mesoscale convective systems (MCSS) in the Tropical West Pacific. The integrated backscatter when the cloud is completely attenuating, and when corrected for multiple scattering, is a measure of the cloud particle backscatter phase function. Four different cases of MCS were studied. The first was very large, very intense, and fully attenuating, with cloud tops extending to 17 km and a maximum lidar pulse penetration of about 3 km. It also exhibited the highest integrated attenuated isotropic backscatter, with values in the 532-nm channel of up to 2.5 near the center of the system, falling to 0.6 near the edges. The second MCS had cloud tops that extended to 14.8 km. Although MCS2 was almost fully attenuating, the pulse penetration into the cloud was up to 7 km and the MCS2 had a more diffuse appearance than MCS1. The integrated backscatter values were much lower in this system but with some systematic variations between 0.44 and 0.75. The third MCS was Typhoon Melissa. Values of integrated backscatter in tt-ds case varied from 1.64 near the eye of the typhoon to between 0.44 and 1.0 in the areas of typhoon outflow and in the 532-nm channel. Mean pulse penetration through the cloud top was 2-3 km, the lowest penetration of any of the systems. The fourth MCS consisted of a region of outflow from Typhoon Melissa. The cloud was semitransparent for more than half of the image time. During that time, maximum cloud depth was about 7 km. The integrated backscatter varied from about 0.38 to 0.63 in the 532-nm channel when the cloud was fully attenuating. In some isolated cirrus between the main systems, a plot of integrated backscatter against one minus the two-way transmittance gave a linear dependence with a maximum value of 0.35 when the clouds were fully attenuating. The effective backscatter

Eratosthenes' Teachings with a Globe in a School Yard

ERIC Educational Resources Information Center

Bozic, Mirjana; Ducloy, Martial

2008-01-01

A globe, in a school or university yard, which simulates the Earth's orientation in space, could be a very useful and helpful device for teaching physics, geometry, astronomy and the history of science. It would be very useful for science education to utilize the forthcoming International Year of the Planet Earth 2008 and the International Year of…

A novel lobster-eye imaging system based on Schmidt-type objective for X-ray-backscattering inspection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Jie; Wang, Xin, E-mail: wangx@tongji.edu.cn, E-mail: mubz@tongji.edu.cn; Zhan, Qi

This paper presents a novel lobster-eye imaging system for X-ray-backscattering inspection. The system was designed by modifying the Schmidt geometry into a treble-lens structure in order to reduce the resolution difference between the vertical and horizontal directions, as indicated by ray-tracing simulations. The lobster-eye X-ray imaging system is capable of operating over a wide range of photon energies up to 100 keV. In addition, the optics of the lobster-eye X-ray imaging system was tested to verify that they meet the requirements. X-ray-backscattering imaging experiments were performed in which T-shaped polymethyl-methacrylate objects were imaged by the lobster-eye X-ray imaging system basedmore » on both the double-lens and treble-lens Schmidt objectives. The results show similar resolution of the treble-lens Schmidt objective in both the vertical and horizontal directions. Moreover, imaging experiments were performed using a second treble-lens Schmidt objective with higher resolution. The results show that for a field of view of over 200 mm and with a 500 mm object distance, this lobster-eye X-ray imaging system based on a treble-lens Schmidt objective offers a spatial resolution of approximately 3 mm.« less

A novel lobster-eye imaging system based on Schmidt-type objective for X-ray-backscattering inspection

NASA Astrophysics Data System (ADS)

Xu, Jie; Wang, Xin; Zhan, Qi; Huang, Shengling; Chen, Yifan; Mu, Baozhong

2016-07-01

This paper presents a novel lobster-eye imaging system for X-ray-backscattering inspection. The system was designed by modifying the Schmidt geometry into a treble-lens structure in order to reduce the resolution difference between the vertical and horizontal directions, as indicated by ray-tracing simulations. The lobster-eye X-ray imaging system is capable of operating over a wide range of photon energies up to 100 keV. In addition, the optics of the lobster-eye X-ray imaging system was tested to verify that they meet the requirements. X-ray-backscattering imaging experiments were performed in which T-shaped polymethyl-methacrylate objects were imaged by the lobster-eye X-ray imaging system based on both the double-lens and treble-lens Schmidt objectives. The results show similar resolution of the treble-lens Schmidt objective in both the vertical and horizontal directions. Moreover, imaging experiments were performed using a second treble-lens Schmidt objective with higher resolution. The results show that for a field of view of over 200 mm and with a 500 mm object distance, this lobster-eye X-ray imaging system based on a treble-lens Schmidt objective offers a spatial resolution of approximately 3 mm.

Low-frequency acousto-optic backscattering of Bessel light beams

NASA Astrophysics Data System (ADS)

Khilo, Nikolai A.; Belyi, Vladimir N.; Khilo, Petr A.; Kazak, Nikolai S.

2018-05-01

The use of Bessel light beams, as well as Bessel acoustic beams, substantially enhances the capabilities of acousto-optic methods for control of optical field. We present a theoretical study of the process of optical Bessel beams conversion by means of backward acousto-optic scattering on a Bessel acoustic field in a transversely isotropic crystal. It is shown that, with an appropriate choice of Bessel beams parameters, the backscattering in visible spectral range can be realized at relatively low acoustic frequencies less than one gigahertz. Under conditions of phase matching and transverse spatial synchronism, the efficiency of backscattering is sufficiently high, which is interesting, for example, for construction of acousto-optic spectral analyzers.

Bathymetry and acoustic backscatter-outer mainland shelf, eastern Santa Barbara Channel, California

USGS Publications Warehouse

Dartnell, Peter; Finlayson, David P.; Ritchie, Andrew C.; Cochrane, Guy R.; Erdey, Mercedes D.

2012-01-01

In 2010 and 2011, scientists from the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC), acquired bathymetry and acoustic-backscatter data from the outer shelf region of the eastern Santa Barbara Channel, California. These surveys were conducted in cooperation with the Bureau of Ocean Energy Management (BOEM). BOEM is interested in maps of hard-bottom substrates, particularly natural outcrops that support reef communities in areas near oil and gas extraction activity. The surveys were conducted using the USGS R/V Parke Snavely, outfitted with an interferometric sidescan sonar for swath mapping and real-time kinematic navigation equipment. This report provides the bathymetry and backscatter data acquired during these surveys in several formats, a summary of the mapping mission, maps of bathymetry and backscatter, and Federal Geographic Data Committee (FGDC) metadata.

Windows Into the Real World From a Virtual Globe

NASA Astrophysics Data System (ADS)

Rich, J.; Urban-Rich, J.

2007-12-01

Virtual globes such as Google Earth can be great tools for learning about the geographical variation of the earth. The key to virtual globes is the use of satellite imagery to provide a highly accurate view of the earth's surface. However, because the images are not updated regularly, variations in climate and vegetation over time can not be easily seen. In order to enhance the view of the earth and observe these changes by region and over time we are working to add near real time "windows" into the real world from a virtual globe. For the past 4 years we have been installing web cameras in areas of the world that will provide long term monitoring of global changes. By archiving hourly images from arctic, temperate and tropical regions we are creating a visual data set that is already beginning to tell the story of climate variability. The cameras are currently installed in 10 elementary schools in 3 countries and show the student's view out each window. The Windows Around the World program (http://www.WindowsAroundTheWorld.org) uses the images from these cameras to help students gain a better understanding of earth process and variability in climate and vegetation between different regions and over time. Previously we have used standard web based technologies such as DHTML and AJAX to provide near real-time access to these images and also provide enhanced functionality such as dynamic time lapse movies that allow users to see changes over months, days or hours up to the current hour (http://www.windowsaroundtheworld.org/north_america.aspx). We have integrated the camera images from Windows Around the World into Google Earth. Through network links and models we are creating a way for students to "fly" to another school in the program and see what the current view is out the window. By using a model as a screen, the image can be viewed from the same direction as the students who are sitting in a classroom at the participating school. Once at the school, visiting

Anisotropy of the apparent frequency dependence of backscatter in formalin fixed human myocardium.

PubMed

Hall, C S; Verdonk, E D; Wickline, S A; Perez, J E; Miller, J G

1997-01-01

Measurements of the frequency dependence of ultrasonic backscatter are presented for specific angles of insonification for regions of infarcted and noninfarcted human myocardium. A 5-MHz transducer was used to insonify cylindrical cores taken from 7 noninfarcted regions and 12 infarcted regions of the left ventricular free wall of 6 formalin-fixed human hearts explanted because of ischemic cardiomyopathy. The dependence of apparent (uncompensated for diffraction effects and attenuation) backscatter on frequency was approximated by a power-law dependence, magnitude of B(f)2 = afn. Under ideal conditions in a lossless medium, the effect of not compensating for the effects of diffraction and attenuation leads to the value of n to be 2.0 for Rayleigh scatterers while the frequency dependence of the fully compensated backscatter coefficient would be f4. The value of n was determined over the frequency range, 3-7 MHz. Both nonifarcted and infarcted myocardium exhibited anisotropy of the frequency dependence of backscatter, with maxima occurring at angles that were perpendicular to the predominant myofiber direction and minima when parallel to the fibers. Perpendicular insonification yielded results for n of 1.8 +/- 0.1 for noninfarcted myocardium and 1.2 +/- 0.1 for infarcted myocardium while parallel insonification yielded results of 0.4 +/- 0.1 for noninfarcted and 0.0 +/- 0.1 for infarcted myocardium. The functional form of the angle-dependent backscatter is similar for both noninfarcted and infarcted myocardium, although the frequency dependence is clearly different for both tissue states for all angles of insonification. The results of this study indicate that the anisotropy of the frequency dependence of backscatter may play a significant role in ultrasonic imaging and is an important consideration for ultrasonic tissue characterization in myocardium.

Recommendations for improved and coherent acquisition and processing of backscatter data from seafloor-mapping sonars

NASA Astrophysics Data System (ADS)

Lamarche, Geoffroy; Lurton, Xavier

2018-06-01

Multibeam echosounders are becoming widespread for the purposes of seafloor bathymetry mapping, but the acquisition and the use of seafloor backscatter measurements, acquired simultaneously with the bathymetric data, are still insufficiently understood, controlled and standardized. This presents an obstacle to well-accepted, standardized analysis and application by end users. The Marine Geological and Biological Habitat Mapping group (Geohab.org) has long recognized the need for better coherence and common agreement on acquisition, processing and interpretation of seafloor backscatter data, and established the Backscatter Working Group (BSWG) in May 2013. This paper presents an overview of this initiative, the mandate, structure and program of the working group, and a synopsis of the BSWG Guidelines and Recommendations to date. The paper includes (1) an overview of the current status in sensors and techniques available in seafloor backscatter data from multibeam sonars; (2) the presentation of the BSWG structure and results; (3) recommendations to operators, end-users, sonar manufacturers, and software developers using sonar backscatter for seafloor-mapping applications, for best practice methods and approaches for data acquisition and processing; and (4) a discussion on the development needs for future systems and data processing. We propose for the first time a nomenclature of backscatter processing levels that affords a means to accurately and efficiently describe the data processing status, and to facilitate comparisons of final products from various origins.

Backscattering measurement of 6He on 209Bi: Critical interaction distance

NASA Astrophysics Data System (ADS)

Guimarães, V.; Kolata, J. J.; Aguilera, E. F.; Howard, A.; Roberts, A.; Becchetti, F. D.; Torres-Isea, R. O.; Riggins, A.; Febrarro, M.; Scarduelli, V.; de Faria, P. N.; Monteiro, D. S.; Huiza, J. F. P.; Arazi, A.; Hinnefeld, J.; Moro, A. M.; Rossi, E. S.; Morcelle, V.; Barioni, A.

2016-06-01

An elastic backscattering experiment has been performed at energies below the Coulomb barrier to investigate static and dynamic effects in the interaction of 6He with 209Bi. The measured cross sections are presented in terms of the d σ /d σR u t h ratio, as a function of the distance of closest approach on a Rutherford trajectory. The data are compared with a three-body CDCC calculation and good agreement is observed. In addition, the critical distance of interaction was extracted. A larger value was obtained for the exotic 6He nucleus as compared with the weakly bound 6Li and 9Be nuclei and the tightly bound 4He12C, and 16O nuclei.

Evaluating multiple causes of persistent low microwave backscatter from Amazon forests after the 2005 drought.

PubMed

Frolking, Steve; Hagen, Stephen; Braswell, Bobby; Milliman, Tom; Herrick, Christina; Peterson, Seth; Roberts, Dar; Keller, Michael; Palace, Michael

2017-01-01

Amazonia has experienced large-scale regional droughts that affect forest productivity and biomass stocks. Space-borne remote sensing provides basin-wide data on impacts of meteorological anomalies, an important complement to relatively limited ground observations across the Amazon's vast and remote humid tropical forests. Morning overpass QuikScat Ku-band microwave backscatter from the forest canopy was anomalously low during the 2005 drought, relative to the full instrument record of 1999-2009, and low morning backscatter persisted for 2006-2009, after which the instrument failed. The persistent low backscatter has been suggested to be indicative of increased forest vulnerability to future drought. To better ascribe the cause of the low post-drought backscatter, we analyzed multiyear, gridded remote sensing data sets of precipitation, land surface temperature, forest cover and forest cover loss, and microwave backscatter over the 2005 drought region in the southwestern Amazon Basin (4°-12°S, 66°-76°W) and in adjacent 8°x10° regions to the north and east. We found moderate to weak correlations with the spatial distribution of persistent low backscatter for variables related to three groups of forest impacts: the 2005 drought itself, loss of forest cover, and warmer and drier dry seasons in the post-drought vs. the pre-drought years. However, these variables explained only about one quarter of the variability in depressed backscatter across the southwestern drought region. Our findings indicate that drought impact is a complex phenomenon and that better understanding can only come from more extensive ground data and/or analysis of frequent, spatially-comprehensive, high-resolution data or imagery before and after droughts.

Evaluating multiple causes of persistent low microwave backscatter from Amazon forests after the 2005 drought

PubMed Central

Hagen, Stephen; Braswell, Bobby; Milliman, Tom; Herrick, Christina; Peterson, Seth; Roberts, Dar; Keller, Michael; Palace, Michael

2017-01-01

Amazonia has experienced large-scale regional droughts that affect forest productivity and biomass stocks. Space-borne remote sensing provides basin-wide data on impacts of meteorological anomalies, an important complement to relatively limited ground observations across the Amazon’s vast and remote humid tropical forests. Morning overpass QuikScat Ku-band microwave backscatter from the forest canopy was anomalously low during the 2005 drought, relative to the full instrument record of 1999–2009, and low morning backscatter persisted for 2006–2009, after which the instrument failed. The persistent low backscatter has been suggested to be indicative of increased forest vulnerability to future drought. To better ascribe the cause of the low post-drought backscatter, we analyzed multiyear, gridded remote sensing data sets of precipitation, land surface temperature, forest cover and forest cover loss, and microwave backscatter over the 2005 drought region in the southwestern Amazon Basin (4°-12°S, 66°-76°W) and in adjacent 8°x10° regions to the north and east. We found moderate to weak correlations with the spatial distribution of persistent low backscatter for variables related to three groups of forest impacts: the 2005 drought itself, loss of forest cover, and warmer and drier dry seasons in the post-drought vs. the pre-drought years. However, these variables explained only about one quarter of the variability in depressed backscatter across the southwestern drought region. Our findings indicate that drought impact is a complex phenomenon and that better understanding can only come from more extensive ground data and/or analysis of frequent, spatially-comprehensive, high-resolution data or imagery before and after droughts. PMID:28873422

Z dependence of thick-target β-ray backscattering

NASA Astrophysics Data System (ADS)

Sharma, K. K.; Singh, M.

1980-04-01

Variation of β-ray backscattering with the atomic number of target material has been studied using thick targets of polythene, aluminum, iron, copper, zinc, tin, silver, tungsten, and lead for five β emitters, viz., 35S, 147Pm, 204Tl, 32P, and 90Sr-90Y. Effects of geometry and β-ray end-point energy have been investigated using a reflection geometry in which the geometry factors were varied by more than 40 and β-ray energy varied over a range 0.167-2.27 MeV. It is found that the mean value of the index of Z dependence of β-ray backscattering is 1.840.05 over these regions of geometry and energy. Deviations for soft β emitters have been confirmed as due to air absorption. The importance of these results in studies of two-component systems is emphasized.

The characteristics simulation of FMCW laser backscattering signals

NASA Astrophysics Data System (ADS)

Liu, Bohu; Song, Chengtian; Duan, Yabo

2018-04-01

A Monte Carlo simulation model of FMCW laser transmission in a smoke interference environment was established in this paper. The aerosol extinction coefficient and scattering coefficient changed dynamically in the simulation according to the smoke concentration variation, aerosol particle distributions and photon spatial positions. The simulation results showed that the smoke backscattering interference produced a number of amplitude peaks in the beat signal spectrum; the SNR of target echo signal to smoke interference was related to the transmitted laser wavelength and the aerosol particle size distribution; a better SNR could be obtained when the laser wavelength was in the range of 560-1660 nm. The characteristics of FMCW laser backscattering signals generated by simulation are consistent with the theoretical analysis. Therefore, this study was greatly helpful for improving the ability of identifying target and anti-interference in the further research.

Backscattering spectrometry device for identifying unknown elements present in a workpiece

DOEpatents

Doyle, Barney L.; Knapp, James A.

1991-01-01

A backscattering spectrometry method and device for identifying and quantifying impurities in a workpiece during processing and manufacturing of that workpiece. While the workpiece is implanted with an ion beam, that same ion beam backscatters resulting from collisions with known atoms and with impurities within the workpiece. Those ions backscatter along a predetermined scattering angle and are filtered using a self-supporting filter to stop the ions with a lower energy because they collided with the known atoms of the workpiece of a smaller mass. Those ions which pass through the filter have a greater energy resulting from impact with impurities having a greater mass than the known atoms of the workpiece. A detector counts the number and measures the energy of the ions which pass through the filter. From the energy determination and knowledge of the scattering angle, a mass calculation determines the identity, and from the number and solid angle of the scattering angle, a relative concentration of the impurity is obtained.

Heavenly Networks. Celestial Maps and Globes in Circulation between Artisans, Mathematicians, and Noblemen in Renaissance Europe.

PubMed

Gessner, Samuel

2015-01-01

The aim of this paper is to examine the iconography on a set of star charts by Albrecht Dürer (1515), and celestial globes by Caspar Vopel (1536) and Christoph Schissler (1575). The iconography on these instruments is conditioned by strong traditions which include not only the imagery on globes and planispheres (star charts), but also ancient literature about the constellations. Where this iconography departs from those traditions, the change had to do with humanism in the sixteenth century. This "humanistic" dimension is interwoven with other concerns that involve both "social" and "technical" motivations. The interplay of these three dimensions illustrates how the iconography on celestial charts and globes expresses some features of the shared knowledge and shared culture between artisans, mathematicians, and nobles in Renaissance Europe.

Estimation of stable boundary-layer height using variance processing of backscatter lidar data

NASA Astrophysics Data System (ADS)

Saeed, Umar; Rocadenbosch, Francesc

2017-04-01

Stable boundary layer (SBL) is one of the most complex and less understood topics in atmospheric science. The type and height of the SBL is an important parameter for several applications such as understanding the formation of haze fog, and accuracy of chemical and pollutant dispersion models, etc. [1]. This work addresses nocturnal Stable Boundary-Layer Height (SBLH) estimation by using variance processing and attenuated backscatter lidar measurements, its principles and limitations. It is shown that temporal and spatial variance profiles of the attenuated backscatter signal are related to the stratification of aerosols in the SBL. A minimum variance SBLH estimator using local minima in the variance profiles of backscatter lidar signals is introduced. The method is validated using data from HD(CP)2 Observational Prototype Experiment (HOPE) campaign at Jülich, Germany [2], under different atmospheric conditions. This work has received funding from the European Union Seventh Framework Programme, FP7 People, ITN Marie Curie Actions Programme (2012-2016) in the frame of ITaRS project (GA 289923), H2020 programme under ACTRIS-2 project (GA 654109), the Spanish Ministry of Economy and Competitiveness - European Regional Development Funds under TEC2015-63832-P project, and from the Generalitat de Catalunya (Grup de Recerca Consolidat) 2014-SGR-583. [1] R. B. Stull, An Introduction to Boundary Layer Meteorology, chapter 12, Stable Boundary Layer, pp. 499-543, Springer, Netherlands, 1988. [2] U. Löhnert, J. H. Schween, C. Acquistapace, K. Ebell, M. Maahn, M. Barrera-Verdejo, A. Hirsikko, B. Bohn, A. Knaps, E. O'Connor, C. Simmer, A. Wahner, and S. Crewell, "JOYCE: Jülich Observatory for Cloud Evolution," Bull. Amer. Meteor. Soc., vol. 96, no. 7, pp. 1157-1174, 2015.

Calibrating nadir striped artifacts in a multibeam backscatter image using the equal mean-variance fitting model

NASA Astrophysics Data System (ADS)

Yang, Fanlin; Zhao, Chunxia; Zhang, Kai; Feng, Chengkai; Ma, Yue

2017-07-01

Acoustic seafloor classification with multibeam backscatter measurements is an attractive approach for mapping seafloor properties over a large area. However, artifacts in the multibeam backscatter measurements prevent accurate characterization of the seafloor. In particular, the backscatter level is extremely strong and highly variable in the near-nadir region due to the specular echo phenomenon. Consequently, striped artifacts emerge in the backscatter image, which can degrade the classification accuracy. This study focuses on the striped artifacts in multibeam backscatter images. To this end, a calibration algorithm based on equal mean-variance fitting is developed. By fitting the local shape of the angular response curve, the striped artifacts are compressed and moved according to the relations between the mean and variance in the near-nadir and off-nadir region. The algorithm utilized the measured data of near-nadir region and retained the basic shape of the response curve. The experimental results verify the high performance of the proposed method.

Diurnal Soil Temperature Effects within the Globe[R] Program Dataset

ERIC Educational Resources Information Center

Witter, Jason D.; Spongberg, Alison L.; Czajkowski, Kevin P.

2007-01-01

Long-term collection of soil temperature with depth is important when studying climate change. The international program GLOBE[R] provides an excellent opportunity to collect such data, although currently endorsed temperature collection protocols need to be refined. To enhance data quality, protocol-based methodology and automated data logging,…

UV-VIS backscattering measurements on atmospheric particles mixture using polarization lidar coupled with numerical simulations and laboratory experiments

NASA Astrophysics Data System (ADS)

Miffre, Alain; Francis, Mirvatte; Anselmo, Christophe; Rairoux, Patrick

2015-04-01

As underlined by the latest IPCC report [1], tropospheric aerosols are nowadays recognized as one of the main uncertainties affecting the Earth's climate and human health. This issue is not straightforward due to the complexity of these nanoparticles, which present a wide range of sizes, shapes and chemical composition, which vary as a function of altitude, especially in the troposphere, where strong temperature variations are encountered under different water vapour content (from 10 to 100 % relative humidity). During this oral presentation, I will first present the scientific context of this research. Then, the UV-VIS polarimeter instrument and the subsequent calibration procedure [2] will be presented, allowing quantitative evaluation of particles backscattering coefficients in the atmosphere. In this way, up to three-component particles external mixtures can be partitioned into their spherical and non-spherical components, by coupling UV-VIS depolarization lidar measurements with numerical simulations of backscattering properties specific to non-spherical particles, such as desert dust or sea-salt particles [3], by applying the T-matrix numerical code [4]. This combined methodology is new, as opposed to the traditional approach using the lidar and T-matrix methodologies separately. In complement, recent laboratory findings [5] and field applications [6] will be presented, enhancing the sensitivity of the UV-VIS polarimeter. References [1] IPCC report, Intergovernmental Panel on Climate Change, IPCC, (2013). [2] G. David, A. Miffre, B. Thomas, and P. Rairoux: "Sensitive and accurate dual-wavelength UV-VIS polarization detector for optical remote sensing of tropospheric aerosols," Appl. Phys. B 108, 197-216 (2012). [3] G. David, B. Thomas, T. Nousiainen, A. Miffre and P. Rairoux: "Retrieving simulated volcanic, desert dust, and sea-salt particle properties from two / three-component particle mixtures using UV-VIS polarization Lidar and T-matrix," Atmos. Chem Phys

Risk factors for poor outcomes in patients with open-globe injuries

PubMed Central

Page, Rita D; Gupta, Sumeet K; Jenkins, Thomas L; Karcioglu, Zeynel A

2016-01-01

Purpose The aim of this study was to identify the risk factors that are predictive of poor outcomes in penetrating globe trauma. Patients and methods This retrospective case series evaluated 103 eyes that had been surgically treated for an open-globe injury from 2007 to 2010 at the eye clinic of the University of Virginia. A total of 64 eyes with complete medical records and at least 6 months of follow-up were included in the study. Four risk factors (preoperative best-corrected visual acuity [pre-op BCVA], ocular trauma score [OTS], zone of injury [ZOI], and time lapse [TL] between injury and primary repair) and three outcomes (final BCVA, monthly rate of additional surgeries [MRAS], and enucleation) were identified for analysis. Results Pre-op BCVA was positively associated with MRAS, final BCVA, and enucleation. Calculated OTS was negatively associated with the outcome variables. No association was found between TL and ZOI with the outcome variables. Further, age and predictor variable-adjusted analyses showed pre-op BCVA to be independently positively associated with MRAS (P=0.008) and with final BCVA (P<0.001), while the calculated OTS was independently negatively associated with final BCVA (P<0.001), but not uniquely associated with MRAS (P=0.530). Conclusion Pre-op BCVA and OTS are best correlated with prognosis in open-globe injuries. However, no conventional features reliably predict the outcome of traumatized eyes. PMID:27536059

Incidence angle normalization of radar backscatter data

USDA-ARS?s Scientific Manuscript database

NASA’s Soil Moisture Passive Active (SMAP) satellite (~2014) will include a radar system that will provide L-band multi-polarization backscatter at a constant incidence angle of 40º. During the pre-launch phase of the project there is a need for observations that will support the radar-based soil mo...

Characterization of highly scattering media by measurement of diffusely backscattered polarized light

DOEpatents

Hielscher, Andreas H.; Mourant, Judith R.; Bigio, Irving J.

2000-01-01

An apparatus and method for recording spatially dependent intensity patterns of polarized light that is diffusely backscattered from highly scattering media are described. These intensity patterns can be used to differentiate different turbid media, such as polystyrene-sphere and biological-cell suspensions. Polarized light from a He-Ne laser (.lambda.=543 nm) is focused onto the surface of the scattering medium, and a surface area of approximately 4.times.4 cm centered on the light input point is imaged through polarization analysis optics onto a CCD camera. A variety of intensity patterns may be observed by varying the polarization state of the incident laser light and changing the analyzer configuration to detect different polarization components of the backscattered light. Experimental results for polystyrene-sphere and Intralipid suspensions demonstrate that the radial and azimuthal variations of the observed pattern depend on the concentration, size, and anisotropy factor, g, of the particles constituting the scattering medium. Measurements performed on biological cell suspensions show that intensity patterns can be used to differentiate between suspensions of cancerous and non-cancerous cells. Introduction of the Mueller-matrix for diffusely backscattered light, permits the selection of a subset of measurements which comprehensively describes the optical properties of backscattering media.

Coherent backscattering of singular beams

NASA Astrophysics Data System (ADS)

Schwartz, Chaim; Dogariu, Aristide

2006-02-01

The phenomenon of coherent backscattering depends on both the statistical characteristics of a random scattering medium and the correlation features of the incident field. Imposing a wavefront singularity on the incident field offers a unique and very attractive way to modify the field correlations in a deterministic manner. The field correlations are found to act as a path-length filter which modifies the distribution of different contributions to the enhancement cone. This effect is thoroughly discussed and demonstrated experimentally for the case of single scale scattering systems.

MSIs across the Globe: Laying the Foundation for Future Research

ERIC Educational Resources Information Center

Hallmark, Tyler; Gasman, Marybeth

2018-01-01

In this paper, we explore the role that Minority Serving Institutions (MSIs) play in democratizing education in the USA and around the world, examining both the institutions and their larger context. We also put forth recommendations for reaching and empowering students attending MSIs and "students at the margins" across the globe.

Science and Math in the Library Media Center Using GLOBE.

ERIC Educational Resources Information Center

Aquino, Teresa L.; Levine, Elissa R.

2003-01-01

Describes the Global Learning and Observations to Benefit the Environment (GLOBE) program which helps school library media specialists and science and math teachers bring earth science, math, information literacy, information technology, and student inquiry into the classroom. Discusses use of the Internet to create a global network to study the…

Ethics and Corporal Punishment within the Schools across the Globe

ERIC Educational Resources Information Center

Rajdev, Usha

2012-01-01

This paper contains cultural anthropological research on various discipline measures used within the classrooms in India, United Kingdom, China, Africa, and the United States. My recent visit to schools in India on study abroad programs prompted my desire to research across the globe different methods of classroom management discipline conducted…

Improved detection and mapping of deepwater hydrocarbon seeps: optimizing multibeam echosounder seafloor backscatter acquisition and processing techniques

NASA Astrophysics Data System (ADS)

Mitchell, Garrett A.; Orange, Daniel L.; Gharib, Jamshid J.; Kennedy, Paul

2018-06-01

Marine seep hunting surveys are a current focus of hydrocarbon exploration surveys due to recent advances in offshore geophysical surveying, geochemical sampling, and analytical technologies. Hydrocarbon seeps are ephemeral, small, discrete, and therefore difficult to sample on the deep seafloor. Multibeam echosounders are an efficient seafloor exploration tool to remotely locate and map seep features. Geophysical signatures from hydrocarbon seeps are acoustically-evident in bathymetric, seafloor backscatter, midwater backscatter datasets. Interpretation of these signatures in backscatter datasets is a fundamental component of commercial seep hunting campaigns. Degradation of backscatter datasets resulting from environmental, geometric, and system noise can interfere with the detection and delineation of seeps. We present a relative backscatter intensity normalization method and an oversampling acquisition technique that can improve the geological resolvability of hydrocarbon seeps. We use Green Canyon (GC) Block 600 in the Northern Gulf of Mexico as a seep calibration site for a Kongsberg EM302 30 kHz MBES prior to the start of the Gigante seep hunting program to analyze these techniques. At GC600, we evaluate the results of a backscatter intensity normalization, assess the effectiveness of 2X seafloor coverage in resolving seep-related features in backscatter data, and determine the off-nadir detection limits of bubble plumes using the EM302. Incorporating these techniques into seep hunting surveys can improve the detectability and sampling of seafloor seeps.

Globe At Night: A Dark-skies Awareness Campaign During The International Year Of Astronomy

NASA Astrophysics Data System (ADS)

Walker, Constance E.; Isbell, D.; Pompea, S. M.; Smith, D. A.; Baker, T.

2009-01-01

GLOBE at Night is an international citizen-science event encouraging everyone, scientists, non-scientists, students and the general public, to measure local levels of light pollution and contribute the observations online to a world map. This program is a centerpiece of the Dark Skies Awareness Global Cornerstone Project for the International Year of Astronomy (IYA) as well as the US IYA "Dark Skies are a Universal Resource” theme for 2009. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved. Utilizing the international networks of its hosts, the GLOBE program at the National Optical Astronomy Observatory, the University Corporation for Atmospheric Research and the Environmental Systems Research Institute, along with the Astronomical Society of the Pacific, the Association of Science and Technology Centers, the Astronomical League and the International Dark-Sky Association, GLOBE at Night is able to engage people from around the world. Data collection and online reporting is simple and user-friendly. During a 13-day campaign in each spring, citizen-scientists take data on light pollution levels by comparing observations with stellar maps of limiting magnitudes toward the constellation, Orion. For more precise measurements, citizen-scientists use digital sky brightness meters. During the campaign period over the last 3 years, 20,000 measurements from 100 countries have been logged. The collected data is available online in a variety of formats and for comparison with data from previous years, Earth at Night satellite data and population density data. We will discuss how students and scientists worldwide can explore and analyze these results. We will provide the "know-how” and the means for session participants to become community advocates for GLOBE at Night in their hometowns. We will also discuss lessons learned, best practices and campaign plans during IYA (March 16-28, 2009). For more

The Use of the Nelder-Mead Method in Determining Projection Parameters for Globe Photographs

NASA Astrophysics Data System (ADS)

Gede, M.

2009-04-01

A photo of a terrestrial or celestial globe can be handled as a map. The only hard issue is its projection: the so-called Tilted Perspective Projection which, if the optical axis of the photo intersects the globe's centre, is simplified to the Vertical Near-Side Perspective Projection. When georeferencing such a photo, the exact parameters of the projections are also needed. These parameters depend on the position of the viewpoint of the camera. Several hundreds of globe photos had to be georeferenced during the Virtual Globes Museum project, which made necessary to automatize the calculation of the projection parameters. The author developed a program for this task which uses the Nelder-Mead Method in order to find the optimum parameters when a set of control points are given as input. The Nelder-Mead method is a numerical algorithm for minimizing a function in a many-dimensional space. The function in the present application is the average error of the control points calculated from the actual values of parameters. The parameters are the geographical coordinates of the projection centre, the image coordinates of the same point, the rotation of the projection, the height of the perspective point and the scale of the photo (calculated in pixels/km). The program reads the Global Mappers Ground Control Point (.GCP) file format as input and creates projection description files (.PRJ) for the same software. The initial values of the geographical coordinates of the projection centre are calculated as the average of the control points, while the other parameters are set to experimental values which represent the most common circumstances of taking a globe photograph. The algorithm runs until the change of the parameters sinks below a pre-defined limit. The minimum search can be refined by using the previous result parameter set as new initial values. This paper introduces the calculation mechanism and examples of the usage. Other possible other usages of the method are

Method and Apparatus for Computed Imaging Backscatter Radiography

NASA Technical Reports Server (NTRS)

Shedlock, Daniel (Inventor); Sabri, Nissia (Inventor); Dugan, Edward T. (Inventor); Jacobs, Alan M. (Inventor); Meng, Christopher (Inventor)

2013-01-01

Systems and methods of x-ray backscatter radiography are provided. A single-sided, non-destructive imaging technique utilizing x-ray radiation to image subsurface features is disclosed, capable of scanning a region using a fan beam aperture and gathering data using rotational motion.

Radar backscatter properties of milo and soybeans

NASA Technical Reports Server (NTRS)

Bush, T. F.; Ulaby, F. T.; Metzler, T.

1975-01-01

The radar backscatter from fields of milo and soybeans was measured with a ground based radar as a function of frequency (8-18 GHz), polarization (HH and VV) and angle of incidence (0 deg-70 deg) during the summer of 1974. Supporting ground truth was gathered contemporaneously with the backscatter data. At nadir sigma deg of milo correlated highly, r = 0.96, with soil moisture in the milo field at 8.6 GHz but decreased to a value of r = 0.78 at a frequency of 17.0 GHz. Correlation studies of the variations of sigma deg with soil moisture in the soybean fields were not possible due to a lack of a meaningful soil moisture dynamic range. At the larger angles of incidence, however, sigma deg of soybeans did appear to be dependent on precipitation. It is suggested this phenomenon was caused by the rain altering plant geometry. In general sigma deg of both milo and soybeans had a relatively small dynamic range at the higher angles of incidence and showed no significant dependence on the measured crop parameters.

Enhanced backscattering of electrons in a magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berkovits, R.; Eliyahu, D.; Kaveh, M.

1990-01-01

We calculate the exact shape of the enhanced coherent backscattering peak for electrons in the presence of an external magnetic field. The interference phenomena that cause the backscattered enhancement are reduced due to the breaking of time-reversal symmetry. It is shown that the form of the peak in the presence of a magnetics field {ital I}({ital q},{ital H}) can be obtained (to a good approximation) from {ital I}({ital q},{ital H}=0) by replacing {ital q} with {ital {tilde q}}=({ital q}{sup 2}+(3L{sub {ital H}}{sup 2}){sup {minus}1}){sup 11}, where {ital L}{sub {ital H}}=(2{h bar}c/eH){sup 1/2}. We have also calculated {ital I}({ital q},{ital H})more » at finite temperatures and proposed it as the most sensitive tool for extracting inelastic processes.« less

Raman Backscatter as a Remote Laser Power Sensor in High-Energy-Density Plasmas [Stimulated Scattering as a Remote Laser Power Sensor in High-Density and Temperature Plasmas

DOE PAGES

Moody, J. D.; Strozzi, D. J.; Divol, L.; ...

2013-07-09

Stimulated Raman backscatter is used as a remote sensor to quantify the instantaneous laser power after transfer from outer to inner cones that cross in a National Ignition Facility (NIF) gas-filled hohlraum plasma. By matching stimulated Raman backscatter between a shot reducing outer versus a shot reducing inner power we infer that about half of the incident outer-cone power is transferred to inner cones, for the specific time and wavelength configuration studied. Furthermore, this is the first instantaneous nondisruptive measure of power transfer in an indirect drive NIF experiment using optical measurements.

Central Radar System, Over-the-Horizon Backscatter

DTIC Science & Technology

1990-03-09

1,2-Dibromo-3- chloropropane (DBCP) 0.3 TABLE 41-6 (Continued). MINNESOTA RECOMMENDED ALLOWABLE LIMITS (RAL) FOR DRINKING WATER WELLS Compound RAL (ug/ 1 ...TABLE OF CONTENTS ENVIRONMENTAL IMPACT ANALYSIS PROCESS OVERVIEW ............ TECHNICAL STUDY 1 FACILITIES...TECHNICAL STUDY 10 0 TECHNICAL STUDY 1 CENTRAL RADAR SYSTEM OVER-THE-HORIZON BACKSCATTER RADAR PROGRAM 0 ENVIRONMENTAL IMPACT

User expectations for multibeam echo sounders backscatter strength data-looking back into the future

NASA Astrophysics Data System (ADS)

Lucieer, Vanessa; Roche, Marc; Degrendele, Koen; Malik, Mashkoor; Dolan, Margaret; Lamarche, Geoffroy

2018-06-01

With the ability of multibeam echo sounders (MBES) to measure backscatter strength (BS) as a function of true angle of insonification across the seafloor, came a new recognition of the potential of backscatter measurements to remotely characterize the properties of the seafloor. Advances in transducer design, digital electronics, signal processing capabilities, navigation, and graphic display devices, have improved the resolution and particularly the dynamic range available to sonar and processing software manufacturers. Alongside these improvements the expectations of what the data can deliver has also grown. In this paper, we identify these user-expectations and explore how MBES backscatter is utilized by different communities involved in marine seabed research at present, and the aspirations that these communities have for the data in the future. The results presented here are based on a user survey conducted by the GeoHab (Marine Geological and Biological Habitat Mapping) association. This paper summarises the different processing procedures employed to extract useful information from MBES backscatter data and the various intentions for which the user community collect the data. We show how a range of backscatter output products are generated from the different processing procedures, and how these results are taken up by different scientific disciplines, and also identify common constraints in handling MBES BS data. Finally, we outline our expectations for the future of this unique and important data source for seafloor mapping and characterisation.

Investigating the role of urban development in the conventional environmental Kuznets curve: evidence from the globe.

PubMed

Katircioglu, Setareh; Katircioglu, Salih; Kilinc, Ceyhun C

2018-03-19

We investigated the role of urbanization in the conventional environmental Kuznets curve (EKC) of the globe. The overall population and rural population were also considered for control purposes. Based on our findings, we suggest that the conventional EKC of the globe is not an inverted U-shape but becomes downward sloping when urban development is added and inverted U-shapes when the overall population and rural population volumes are added.

The GLOBAL Learning and Observations to Benefit the Environment (GLOBE) Data Visualization and Retrieval System. Building a robust system for scientists and students.

NASA Astrophysics Data System (ADS)

Overoye, D.; Lewis, C.; Butler, D. M.; Andersen, T. J.

2016-12-01

The Global Learning and Observations to Benefit the Environment (GLOBE) Program is a worldwide hands-on, primary and secondary school-based science and education program founded on Earth Day 1995. Implemented in 117 countries, GLOBE promotes the teaching and learning of science, supporting students, teachers and scientists worldwide to collaborate with each other on inquiry-based investigations of the Earth system. The GLOBE Data Information System (DIS) currently supports users with the ability to enter data from over 50 different science protocols. GLOBE's Data Access and Visualization tools have been developed to accommodate the need to display and retrieve data from this large number of protocols. The community of users is also diverse, including NASA scientists, citizen scientists and grade school students. The challenge for GLOBE is to meet the needs from this diverse set of users with protocol specific displays that are simple enough for a GLOBE school to use, but also provide enough features for a NASA Scientist to retrieve data sets they are interested in. During the last 3 years, the GLOBE visualization system has evolved to meet the needs of these various users, leveraging user feedback and technological advances. Further refinements and enhancements continue. In this session we review the design and capabilities of the GLOBE visualization and data retrieval tool set, discuss the evolution of these tools, and discuss coming directions.

Astronomy Meets the Environmental Sciences: Using GLOBE at Night Data

NASA Astrophysics Data System (ADS)

Barringer, D.; Walker, C. E.; Pompea, S. M.; Sparks, R. T.

2011-09-01

The GLOBE at Night database now contains over 52,000 observations from the five annual two-week campaigns. It can be used as a resource to explore various issues related to light pollution and our environment. Students can compare data over time to look for changes and trends. For example, they can compare the data to population density or with nighttime photography and spectroscopy of lights. The data can be used in a lighting survey, to search for dark sky oases or to monitor ordinance compliance. Students can study effects of light pollution on animals, plants, human health, safety, security, energy consumption, and cost. As an example, we used data from the GLOBE at Night project and telemetry tracking data of lesser long-nosed bats obtained by the Arizona Game and Fish Department to study the effects of light pollution on the flight paths of the bats between their day roosts and night foraging areas around the city of Tucson, AZ. With the visual limiting magnitude data from GLOBE at Night, we ran a compositional analysis with respect to the bats' flight paths to determine whether the bats were selecting for or against flight through regions of particular night sky brightness levels. We found that the bats selected for the regions in which the limiting sky magnitudes fell between the ranges of 2.8-3.0 to 3.6-3.8 and 4.4-4.6 to 5.0-5.2, suggesting that the lesser long-nosed bat can tolerate a fair degree of urbanization. We also compared this result to contour maps created with digital Sky Quality Meter (http://www.unihedron.com) data.

ATRF Earns Three Green Globes, Exceeds NIH Building Standards | Poster

Cancer.gov

By Ashley DeVine, Staff Writer From project management and energy and water efficiency to emissions and the indoor environment, the Advanced Technology Research Facility (ATRF) was built with sustainability in mind, exceeding the National Institutes of Health’s (NIH’s) building standards and earning three Green Globes from the Green Building Initiative (GBI).

Backscattering analysis of high frequency ultrasonic imaging for ultrasound-guided breast biopsy

NASA Astrophysics Data System (ADS)

Cummins, Thomas; Akiyama, Takahiro; Lee, Changyang; Martin, Sue E.; Shung, K. Kirk

2017-03-01

A new ultrasound-guided breast biopsy technique is proposed. The technique utilizes conventional ultrasound guidance coupled with a high frequency embedded ultrasound array located within the biopsy needle to improve the accuracy in breast cancer diagnosis.1 The array within the needle is intended to be used to detect micro- calcifications indicative of early breast cancers such as ductal carcinoma in situ (DCIS). Backscattering analysis has the potential to characterize tissues to improve localization of lesions. This paper describes initial results of the application of backscattering analysis of breast biopsy tissue specimens and shows the usefulness of high frequency ultrasound for the new biopsy related technique. Ultrasound echoes of ex-vivo breast biopsy tissue specimens were acquired by using a single-element transducer with a bandwidth from 41 MHz to 88 MHz utilizing a UBM methodology, and the backscattering coefficients were calculated. These values as well as B-mode image data were mapped in 2D and matched with each pathology image for the identification of tissue type for the comparison to the pathology images corresponding to each plane. Microcalcifications were significantly distinguished from normal tissue. Adenocarcinoma was also successfully differentiated from adipose tissue. These results indicate that backscattering analysis is able to quantitatively distinguish tissues into normal and abnormal, which should help radiologists locate abnormal areas during the proposed ultrasound-guided breast biopsy with high frequency ultrasound.

Improving the detection of wind fields from LIDAR aerosol backscatter using feature extraction

NASA Astrophysics Data System (ADS)

Bickel, Brady R.; Rotthoff, Eric R.; Walters, Gage S.; Kane, Timothy J.; Mayor, Shane D.

2016-04-01

The tracking of winds and atmospheric features has many applications, from predicting and analyzing weather patterns in the upper and lower atmosphere to monitoring air movement from pig and chicken farms. Doppler LIDAR systems exist to quantify the underlying wind speeds, but cost of these systems can sometimes be relatively high, and processing limitations exist. The alternative is using an incoherent LIDAR system to analyze aerosol backscatter. Improving the detection and analysis of wind information from aerosol backscatter LIDAR systems will allow for the adoption of these relatively low cost instruments in environments where the size, complexity, and cost of other options are prohibitive. Using data from a simple aerosol backscatter LIDAR system, we attempt to extend the processing capabilities by calculating wind vectors through image correlation techniques to improve the detection of wind features.

Open globe injury with an interesting intra-ocular foreign body

PubMed Central

Gill, Ekjyot; Shulman, Matthew; Schechet, Sid; Grumbine, Lawson

2017-01-01

Introduction: Cases of penetrating ocular trauma due to osseous material are limited, so reported incidents are valuable in determining outcomes and proper treatment courses. Case description: We report a case of an open globe injury of the left eye with an intraocular foreign body occurring after a firework exploded in the hand of a 22-year-old man. The patient presented with light perception vision in the injured eye with a full-thickness limbal laceration and dense hyphema obscuring fundoscopy. CT scan revealed a hyperdense foreign body juxtaposed to the lens. Immediate surgical intervention to repair the globe rupture revealed a defect in the anterior capsule and small, white objects in the posterior chamber that were promptly removed. Pathologic investigation determined these fragments to be cortical bone likely from the patient’s phalanges. Results and discussion: There was no evidence of endophthalmitis or keratitis from time of injury to the five-month follow-up, suggesting that the risk of infection may be low and therefore it may be reasonable to manage these injuries with a period of observation. PMID:28706770

Probing insect backscatter cross section and melanization using kHz optical remote detection system

NASA Astrophysics Data System (ADS)

Gebru, Alem; Brydegaard, Mikkel; Rohwer, Erich; Neethling, Pieter

2017-01-01

A kHz optical remote sensing system is implemented to determine insect melanization features. This is done by measuring the backscatter signal in the visible and near-infrared (VIS-NIR) and short-wave infrared (SWIR) in situ. It is shown that backscatter cross section in the SWIR is insensitive to melanization and absolute melanization can be derived from the ratio of backscatter cross section of different bands (SWIR/VIS-NIR). We have shown that reflectance from insect is stronger in the SWIR as compared to NIR and VIS. This reveals that melanization plays a big role to determine backscatter cross section. One can use this feature as a tool to improve insect species and age classification. To support the findings, we illustrated melanization feature using three different insects [dead, dried specimens of snow white moth (Spilosoma genus), fox moth (Macrothylacia), and leather beetle (Odontotaenius genus)]. It is shown that reflectance from the leather beetle in the VIS and NIR is more affected by melanization as compared with snow white moth.

Monte Carlo simulation for coherent backscattering with diverging illumination (Conference Presentation)

NASA Astrophysics Data System (ADS)

Wu, Wenli; Radosevich, Andrew J.; Eshein, Adam; Nguyen, The-Quyen; Backman, Vadim

2016-03-01

Diverging beam illumination is widely used in many optical techniques especially in fiber optic applications and coherence phenomenon is one of the most important properties to consider for these applications. Until now, people have used Monte Carlo simulations to study the backscattering coherence phenomenon in collimated beam illumination only. We are the first one to study the coherence phenomenon under the exact diverging beam geometry by taking into account the impossibility of the existence for the exact time-reversed path pairs of photons, which is the main contribution to the backscattering coherence pattern in collimated beam. In this work, we present a Monte Carlo simulation that considers the influence of the illumination numerical aperture. The simulation tracks the electric field for the unique paths of forward path and reverse path in time-reversed pairs of photons as well as the same path shared by them. With this approach, we can model the coherence pattern formed between the pairs by considering their phase difference at the collection plane directly. To validate this model, we use the Low-coherence Enhanced Backscattering Spectroscopy, one of the instruments looking at the coherence pattern using diverging beam illumination, as the benchmark to compare with. In the end, we show how this diverging configuration would significantly change the coherent pattern under coherent light source and incoherent light source. This Monte Carlo model we developed can be used to study the backscattering phenomenon in both coherence and non-coherence situation with both collimated beam and diverging beam setups.

Coherent Backscattering by Polydisperse Discrete Random Media: Exact T-Matrix Results

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Dlugach, Janna M.; Mackowski, Daniel W.

2011-01-01

The numerically exact superposition T-matrix method is used to compute, for the first time to our knowledge, electromagnetic scattering by finite spherical volumes composed of polydisperse mixtures of spherical particles with different size parameters or different refractive indices. The backscattering patterns calculated in the far-field zone of the polydisperse multiparticle volumes reveal unequivocally the classical manifestations of the effect of weak localization of electromagnetic waves in discrete random media, thereby corroborating the universal interference nature of coherent backscattering. The polarization opposition effect is shown to be the least robust manifestation of weak localization fading away with increasing particle size parameter.

Shallow water acoustic backscatter and reverberation measurements using a 68-kHz cylindrical array

NASA Astrophysics Data System (ADS)

Gallaudet, Timothy Cole

2001-10-01

The characterization of high frequency, shallow water acoustic backscatter and reverberation is important because acoustic systems are used in many scientific, commercial, and military applications. The approach taken is to use data collected by the Toroidal Volume Search Sonar (TVSS), a 68 kHz multibeam sonar capable of 360° imaging in a vertical plane perpendicular to its direction of travel. With this unique capability, acoustic backscatter imagery of the seafloor, sea surface, and horizontal and vertical planes in the volume are constructed from data obtained in 200m deep waters in the Northeastern Gulf of Mexico when the TVSS was towed 78m below the surface, 735m astern of a towship. The processed imagery provide a quasi-synoptic characterization of the spatial and temporal structure of boundary and volume acoustic backscatter and reverberation. Diffraction, element patterns, and high sidelobe levels are shown to be the most serious problems affecting cylindrical arrays such as the TVSS, and an amplitude shading method is presented for reducing the peak sidelobe levels of irregular-line and non-coplanar arrays. Errors in the towfish's attitude and motion sensor, and irregularities in the TVSS's transmitted beampattern produce artifacts in the TVSS-derived bathymetry and seafloor acoustic backscatter imagery. Correction strategies for these problems are described, which are unique in that they use environmental information extracted from both ocean boundaries. Sea surface and volume acoustic backscatter imagery are used to explore and characterize the structure of near-surface bubble clouds, schooling fish, and zooplankton. The simultaneous horizontal and vertical coverage provided by the TVSS is shown to be a primary advantage, motivating further use of multibeam sonars in these applications. Whereas boundary backscatter fluctuations are well described by Weibull, K, and Rayleigh mixture probability distributions, those corresponding to volume backscatter are

Ice Cloud Backscatter Study and Comparison with CALIPSO and MODIS Satellite Data

NASA Technical Reports Server (NTRS)

Ding, Jiachen; Yang, Ping; Holz, Robert E.; Platnick, Steven; Meyer, Kerry G.; Vaughan, Mark A.; Hu, Yongxiang; King, Michael D.

2016-01-01

An invariant imbedding T-matrix (II-TM) method is used to calculate the single-scattering properties of 8-column aggregate ice crystals. The II-TM based backscatter values are compared with those calculated by the improved geometric-optics method (IGOM) to refine the backscattering properties of the ice cloud radiative model used in the MODIS Collection 6 cloud optical property product. The integrated attenuated backscatter-to-cloud optical depth (IAB-ICOD) relation is derived from simulations using a CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite) lidar simulator based on a Monte Carlo radiative transfer model. By comparing the simulation results and co-located CALIPSO and MODIS (Moderate Resolution Imaging Spectroradiometer) observations, the non-uniform zonal distribution of ice clouds over ocean is characterized in terms of a mixture of smooth and rough ice particles. The percentage of the smooth particles is approximately 6 percent and 9 percent for tropical and mid-latitude ice clouds, respectively.

Monte Carlo study of backscattering of. beta. rays from various monoatomic slabs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pandey, L. N.; Rustgi, M. L.

1989-07-01

A Monte Carlo study of the backscattering coefficients and backscatteringintensity of ..beta.. rays from /sup 204/ Tl and /sup 90/ Y sources from slabs of Al,Cu, Sn, Tb, and Pb of different thicknesses is carried out. The results forangles of incidence 0/degree/, 30/degree/, 45/degree/, and 60/degree/ and absorber thicknesses of 3,5, 10, 15, 30, and 50 mg/cm/sup 2/ for /sup 204/ Tl ..beta.. rays and thicknesses of3, 5, 10, 20, 50, 100, 150, and 190 mg/cm/sup 2/ for /sup 90/ Y ..beta.. rays aregiven in tabular form. On using normalization factors good agreement with themeasurements of Sharma and Singh ismore » obtained. A phenomenological attempt toinvestigate a relationship between the backscatter intensity and atomic number/ital Z/ of the backscatterer indicates that the backscattered intensity is alinear function of ln /ital Z/(/ital Z/+1). A partial theoretical justification forthis relationship is given.« less

Surface Parameters of Titan Feature Classes From Cassini RADAR Backscatter Measurements

NASA Astrophysics Data System (ADS)

Wye, L. C.; Zebker, H. A.; Lopes, R. M.; Peckyno, R.; Le Gall, A.; Janssen, M. A.

2008-12-01

Multimode microwave measurements collected by the Cassini RADAR instrument during the spacecraft's first four years of operation form a fairly comprehensive set of radar backscatter data over a variety of Titan surface features. We use the real-aperture scatterometry processor to analyze the entire collection of active data, creating a uniformly-calibrated dataset that covers 93% of Titan's surface at a variety of viewing angles. Here, we examine how the measured backscatter response (radar reflectivity as a function of incidence angle) varies with surface feature type, such as dunes, cryovolcanic areas, and anomalous albedo terrain. We identify the feature classes using a combination of maps produced by the RADAR, ISS, and VIMS instruments. We then derive surface descriptors including roughness, dielectric constant, and degree of volume scatter. Radar backscatter on Titan is well-modeled as a superposition of large-scale surface scattering (quasispecular scattering) together with a combination of small-scale surface scattering and subsurface volume scattering (diffuse scattering). The viewing geometry determines which scattering mechanism is strongest. At low incidence angles, quasispecular scatter dominates the radar backscatter return. At higher incidence angles (angles greater than ~30°), diffuse scatter dominates the return. We use a composite model to separate the two scattering regimes; we model the quasispecular term with a combination of two traditional backscatter laws (we consider the Hagfors, Gaussian, and exponential models), following a technique developed by Sultan-Salem and Tyler [1], and we model the diffuse term, which encompasses both diffuse mechanisms, with a simple cosine power law. Using this total composite model, we analyze the backscatter curves of all features classes on Titan for which we have adequate angular coverage. In most cases, we find that the superposition of the Hagfors law with the exponential law best models the

Inversion of atmospheric optical parameters from elastic-backscatter lidar returns using a Kalman filter

NASA Astrophysics Data System (ADS)

Rocadenbosch, Francesc; Comeron, Adolfo; Vazquez, Gregori; Rodriguez-Gomez, Alejandro; Soriano, Cecilia; Baldasano, Jose M.

1998-12-01

Up to now, retrieval of the atmospheric extinction and backscatter has mainly relied on standard straightforward non-memory procedures such as slope-method, exponential- curve fitting and Klett's method. Yet, their performance becomes ultimately limited by the inherent lack of adaptability as they only work with present returns and neither past estimations, nor the statistics of the signals or a prior uncertainties are taken into account. In this work, a first inversion of the backscatter and extinction- to-backscatter ratio from pulsed elastic-backscatter lidar returns is tackled by means of an extended Kalman filter (EKF), which overcomes these limitations. Thus, as long as different return signals income,the filter updates itself weighted by the unbalance between the a priori estimates of the optical parameters and the new ones based on a minimum variance criterion. Calibration errors or initialization uncertainties can be assimilated also. The study begins with the formulation of the inversion problem and an appropriate stochastic model. Based on extensive simulation and realistic conditions, it is shown that the EKF approach enables to retrieve the sought-after optical parameters as time-range-dependent functions and hence, to track the atmospheric evolution, its performance being only limited by the quality and availability of the 'a priori' information and the accuracy of the atmospheric model assumed. The study ends with an encouraging practical inversion of a live-scene measured with the Nd:YAG elastic-backscatter lidar station at our premises in Barcelona.

The Pale Blue Dot: Utilizing Real World Globes in High School and Undergraduate Oceanography Classrooms

NASA Astrophysics Data System (ADS)

Rogers, D. B.

2017-12-01

Geoscience classrooms have benefitted greatly from the use of interactive, dry-erasable globes to supplement instruction on topics that require three-dimensional visualization, such as seismic wave propagation and the large-scale movements of tectonic plates. Indeed, research by Bamford (2013) demonstrates that using three-dimensional visualization to illustrate complex processes enhances student comprehension. While some geoscience courses tend to bake-in lessons on visualization, other disciplines of earth science that require three-dimensional visualization, such as oceanography, tend to rely on students' prior spatial abilities. In addition to spatial intelligence, education on the three-dimensional structure of the ocean requires knowledge of the external processes govern the behavior of the ocean, as well as the vertical and lateral distribution of water properties around the globe. Presented here are two oceanographic activities that utilize RealWorldGlobes' dry-erase globes to supplement traditional oceanography lessons on thermohaline and surface ocean circulation. While simultaneously promoting basic plotting techniques, mathematical calculations, and unit conversions, these activities touch on the processes that govern global ocean circulation, the principles of radiocarbon dating, and the various patterns exhibited by surface ocean currents. These activities challenge students to recognize inherent patterns within their data and synthesize explanations for their occurrence. Spatial visualization and critical thinking are integral to any geoscience education, and the combination of these abilities with engaging hands-on activities has the potential to greatly enhance oceanography education in both secondary and postsecondary settings

The sapphire backscattering monochromator at the Dynamics beamline P01 of PETRA III

DOE PAGES

Alexeev, P.; Asadchikov, V.; Bessas, D.; ...

2016-02-23

Here, we report on a high resolution sapphire backscattering monochromator installed at the Dynamics beamline P01 of PETRA III. The device enables nuclear resonance scattering experiments on M ossbauer isotopes with transition energies between 20 and 60 keV with sub-meV to meV resolution. In a first performance test with 119Sn nuclear resonance at a X-ray energy of 23.88 keV an energy resolution of 1.34 meV was achieved. Moreover, the device extends the field of nuclear resonance scattering at the PETRA III synchrotron light source to many further isotopes like 151Eu, 149Sm, 161Dy, 125Te and 121Sb.

Effects of vegetation canopy on the radar backscattering coefficient

NASA Technical Reports Server (NTRS)

Mo, T.; Blanchard, B. J.; Schmugge, T. J.

1983-01-01

Airborne L- and C-band scatterometer data, taken over both vegetation-covered and bare fields, were systematically analyzed and theoretically reproduced, using a recently developed model for calculating radar backscattering coefficients of rough soil surfaces. The results show that the model can reproduce the observed angular variations of radar backscattering coefficient quite well via a least-squares fit method. Best fits to the data provide estimates of the statistical properties of the surface roughness, which is characterized by two parameters: the standard deviation of surface height, and the surface correlation length. In addition, the processes of vegetation attenuation and volume scattering require two canopy parameters, the canopy optical thickness and a volume scattering factor. Canopy parameter values for individual vegetation types, including alfalfa, milo and corn, were also determined from the best-fit results. The uncertainties in the scatterometer data were also explored.

Backscattering from a randomly rough dielectric surface

NASA Technical Reports Server (NTRS)

Fung, Adrian K.; Li, Zongqian; Chen, K. S.

1992-01-01

A backscattering model for scattering from a randomly rough dielectric surface is developed based on an approximate solution of a pair of integral equations for the tangential surface fields. Both like and cross-polarized scattering coefficients are obtained. It is found that the like polarized scattering coefficients contain two types of terms: single scattering terms and multiple scattering terms. The single scattering terms in like polarized scattering are shown to reduce the first-order solutions derived from the small perturbation method when the roughness parameters satisfy the slightly rough conditions. When surface roughnesses are large but the surface slope is small, only a single scattering term corresponding to the standard Kirchhoff model is significant. If the surface slope is large, the multiple scattering term will also be significant. The cross-polarized backscattering coefficients satisfy reciprocity and contain only multiple scattering terms. The difference between vertical and horizontal scattering coefficients is found to increase with the dielectric constant and is generally smaller than that predicted by the first-order small perturbation model. Good agreements are obtained between this model and measurements from statistically known surfaces.

Corneal backscatter in insulin-dependent and non-insulin-dependent diabetes mellitus patients: a pilot study.

PubMed

Calvo-Maroto, Ana M; Pérez-Cambrodí, Rafael J; Esteve-Taboada, José J; García-Lázaro, Santiago; Cerviño, Aleja Ndro

2017-06-01

To compare central corneal backscatter obtained from Scheimpflug images between patients with insulin-dependent and non-insulin-dependent diabetes mellitus (IDDM and NIDDM, respectively) and healthy controls. Seven patients with IDDM (7 eyes), eleven patients with NIDDM (11 eyes), and sixteen healthy subjects (16 eyes) were included in this pilot study. Scheimpflug imaging system (Pentacam, Oculus Inc., Germany) was used to obtain optical sections of the cornea. Seven meridians were analyzed for each eye, oriented from 70° to 110°. Optical density values for the central 3-mm and 5-mm zones of the cornea were obtained by image analysis using external software. Corneal backscatter was significantly higher in the diabetic patients than in the controls for the central 3-mm (p=0.016) and 5-mm (p=0.014) zones. No significant differences in corneal backscatter were found between the IDDM and NIDDM groups for either zone (both p>0.05). In the NIDDM group, significant correlations were observed for both central zones between corneal backscatter and age (3 mm: r=0.604, p=0.025; 5 mm: r=0.614, p=0.022) and central corneal thickness (3 mm: r=0.641, p=0.017; 5 mm: r=0.671, p=0.012); this was not found in the IDDM group (p>0.05). The presence of diabetes showed a significant effect on central corneal backscatter (Kruskal-Wallis test, p<0.001). Diabetic patients showed higher values of corneal light backscatter than healthy subjects. Corneal optical density analysis may be a useful tool for monitoring and assessing the ocular changes caused by diabetes.

Emergent risk factors associated with eyeball loss and ambulatory vision loss after globe injuries.

PubMed

Hyun Lee, Seung; Ahn, Jae Kyoun

2010-07-01

The objective of this study was to evaluate risk factors associated with eyeball loss and ambulatory vision loss on emergent examination of patients with ocular trauma. We reviewed the medical records of 1,875 patients hospitalized in a single tertiary referral center between January 2003 and December 2007. Emergent examinations included a history of trauma, elapsed time between injury and hospital arrival, visible intraocular tissues, and initial visual acuity (VA) using a penlight. The main outcome measures were ocular survival and ambulatory vision survival (>20/200) at 1 year after trauma using univariate and multivariate regression analysis. The ocular trauma scores were significantly higher in open globe injuries than in closed globe injuries (p < 0.01). In open globe injuries, initial VA less than light perception (LP) and a history of golf ball injury were the significant risk factors associated with eyeball loss. Elapsed time more than 12 hours and visible intraocular tissues were the significant risk factors associated with ambulatory vision loss. The most powerful predictor of eyeball loss and ambulatory vision loss was eyeball rupture. In closed globe injuries, there were no significant risk factors of eyeball loss, whereas initial vision less than LP and the presence of relative afferent pupillary defect were the significant risk factors associated with ambulatory vision loss. An initial VA less than LP using a penlight, a history of golf ball injury, and elapsed time more than 12 hours between ocular trauma and hospital arrival were associated with eyeball loss and ambulatory vision loss. Physicians should bear these factors in mind so that they can more effectively counsel patients with such injuries.

Oxygen Saturation in Closed-Globe Blunt Ocular Trauma

PubMed Central

Long, Chongde; Wen, Xin; Gao, Qianying

2016-01-01

Purpose. To evaluate the oxygen saturation in retinal blood vessels in patients after closed-globe blunt ocular trauma. Design. Retrospective observational case series. Methods. Retinal oximetry was performed in both eyes of 29 patients with unilateral closed-globe blunt ocular trauma. Arterial oxygen saturation (SaO2), venous oxygen saturation (SvO2), arteriovenous difference in oxygen saturation (SO2), arteriolar diameter, venular diameter, and arteriovenous difference in diameter were measured. Association parameters including age, finger pulse oximetry, systolic pressure, diastolic pressure, and heart rate were analyzed. Results. The mean SaO2 in traumatic eyes (98.1% ± 6.8%) was not significantly different from SaO2 in unaffected ones (95.3% ± 7.2%) (p = 0.136). Mean SvO2 in traumatic eyes (57.1% ± 10.6%) was significantly lower than in unaffected ones (62.3% ± 8.4%) (p = 0.044). The arteriovenous difference in SO2 in traumatic eyes (41.0% ± 11.2%) was significantly larger than in unaffected ones (33.0% ± 6.9%) (p = 0.002). No significant difference was observed between traumatic eyes and unaffected ones in arteriolar (p = 0.249) and venular diameter (p = 0.972) as well as arteriovenous difference in diameter (p = 0.275). Conclusions. Oxygen consumption is increased in eyes after cgBOT, associated with lower SvO2 and enlarged arteriovenous difference in SO2 but not with changes in diameter of retinal vessels. PMID:27699174

Differences in Vvufgt and VvmybA1 Gene Expression Levels and Phenolic Composition in Table Grape (Vitis vinifera L.) 'Red Globe' and Its Somaclonal Variant 'Pink Globe'.

PubMed

Bustamante, Luis; Sáez, Vania; Hinrichsen, Patricio; Castro, María H; Vergara, Carola; von Baer, Dietrich; Mardones, Claudia

2017-04-05

A novel 'Red Globe' (RG)-derived grape variety, 'Pink Globe' (PG), was described and registered as a new genotype, with earlier ripening and sweeter taste than those of RG. Microsatellite analysis revealed that PG and RG are undifferentiable; however, the PG VvmybA1c contains six single-nucleotide polymorphisms within the coding and noncoding region, possibly related to the reduced VvmybA1 expression levels. Conversely, HPLC-DAD-ESI-MS/MS analysis showed significantly lower anthocyanin content in PG skin than in RG skin, and PG had no detectable trihydroxylated anthocyanins. Total flavonols did not differ between the variants, although some quercetin derivate concentrations were lower in PG. HPLC-FLD analysis revealed slightly higher concentrations of epicatechin and a procyanidin dimer in PG seeds, although the antioxidant capacity of crude extracts from either variety did not differ significantly. These differences, particularly in monomeric anthocyanin content, can be attributed to altered activity of a MYB-type transcription factor, reducing Vvufgt expression.

50 kHz bottom backscattering measurements from two types of artificially roughened sandy bottoms

NASA Astrophysics Data System (ADS)

Son, Su-Uk; Cho, Sungho; Choi, Jee Woong

2016-07-01

Laboratory measurements of 50 kHz bottom backscattering strengths as a function of grazing angle were performed on the sandy bottom of a water tank; two types of bottom roughnesses, a relatively smooth interface and a rough interface, were created on the bottom surface. The roughness profiles of the two interface types were measured directly using an ultrasound arrival time difference of 5 MHz and then were Fourier transformed to obtain the roughness power spectra. The measured backscattering strengths increased from -29 to 0 dB with increasing grazing angle from 35 to 86°, which were compared to theoretical backscattering model predictions. The comparison results implied that bottom roughness is a key factor in accurately predicting bottom scattering for a sandy bottom.

X-ray backscatter imaging for radiography by selective detection and snapshot: Evolution, development, and optimization

NASA Astrophysics Data System (ADS)

Shedlock, Daniel

Compton backscatter imaging (CBI) is a single-sided imaging technique that uses the penetrating power of radiation and unique interaction properties of radiation with matter to image subsurface features. CBI has a variety of applications that include non-destructive interrogation, medical imaging, security and military applications. Radiography by selective detection (RSD), lateral migration radiography (LMR) and shadow aperture backscatter radiography (SABR) are different CBI techniques that are being optimized and developed. Radiography by selective detection (RSD) is a pencil beam Compton backscatter imaging technique that falls between highly collimated and uncollimated techniques. Radiography by selective detection uses a combination of single- and multiple-scatter photons from a projected area below a collimation plane to generate an image. As a result, the image has a combination of first- and multiple-scatter components. RSD techniques offer greater subsurface resolution than uncollimated techniques, at speeds at least an order of magnitude faster than highly collimated techniques. RSD scanning systems have evolved from a prototype into near market-ready scanning devices for use in a variety of single-sided imaging applications. The design has changed to incorporate state-of-the-art detectors and electronics optimized for backscatter imaging with an emphasis on versatility, efficiency and speed. The RSD system has become more stable, about 4 times faster, and 60% lighter while maintaining or improving image quality and contrast over the past 3 years. A new snapshot backscatter radiography (SBR) CBI technique, shadow aperture backscatter radiography (SABR), has been developed from concept and proof-of-principle to a functional laboratory prototype. SABR radiography uses digital detection media and shaded aperture configurations to generate near-surface Compton backscatter images without scanning, similar to how transmission radiographs are taken. Finally, a

Estimating random errors due to shot noise in backscatter lidar observations.

PubMed

Liu, Zhaoyan; Hunt, William; Vaughan, Mark; Hostetler, Chris; McGill, Matthew; Powell, Kathleen; Winker, David; Hu, Yongxiang

2006-06-20

We discuss the estimation of random errors due to shot noise in backscatter lidar observations that use either photomultiplier tube (PMT) or avalanche photodiode (APD) detectors. The statistical characteristics of photodetection are reviewed, and photon count distributions of solar background signals and laser backscatter signals are examined using airborne lidar observations at 532 nm using a photon-counting mode APD. Both distributions appear to be Poisson, indicating that the arrival at the photodetector of photons for these signals is a Poisson stochastic process. For Poisson- distributed signals, a proportional, one-to-one relationship is known to exist between the mean of a distribution and its variance. Although the multiplied photocurrent no longer follows a strict Poisson distribution in analog-mode APD and PMT detectors, the proportionality still exists between the mean and the variance of the multiplied photocurrent. We make use of this relationship by introducing the noise scale factor (NSF), which quantifies the constant of proportionality that exists between the root mean square of the random noise in a measurement and the square root of the mean signal. Using the NSF to estimate random errors in lidar measurements due to shot noise provides a significant advantage over the conventional error estimation techniques, in that with the NSF, uncertainties can be reliably calculated from or for a single data sample. Methods for evaluating the NSF are presented. Algorithms to compute the NSF are developed for the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations lidar and tested using data from the Lidar In-space Technology Experiment.

Estimating Random Errors Due to Shot Noise in Backscatter Lidar Observations

NASA Technical Reports Server (NTRS)

Liu, Zhaoyan; Hunt, William; Vaughan, Mark A.; Hostetler, Chris A.; McGill, Matthew J.; Powell, Kathy; Winker, David M.; Hu, Yongxiang

2006-01-01

In this paper, we discuss the estimation of random errors due to shot noise in backscatter lidar observations that use either photomultiplier tube (PMT) or avalanche photodiode (APD) detectors. The statistical characteristics of photodetection are reviewed, and photon count distributions of solar background signals and laser backscatter signals are examined using airborne lidar observations at 532 nm using a photon-counting mode APD. Both distributions appear to be Poisson, indicating that the arrival at the photodetector of photons for these signals is a Poisson stochastic process. For Poisson-distributed signals, a proportional, one-to-one relationship is known to exist between the mean of a distribution and its variance. Although the multiplied photocurrent no longer follows a strict Poisson distribution in analog-mode APD and PMT detectors, the proportionality still exists between the mean and the variance of the multiplied photocurrent. We make use of this relationship by introducing the noise scale factor (NSF), which quantifies the constant of proportionality that exists between the root-mean-square of the random noise in a measurement and the square root of the mean signal. Using the NSF to estimate random errors in lidar measurements due to shot noise provides a significant advantage over the conventional error estimation techniques, in that with the NSF uncertainties can be reliably calculated from/for a single data sample. Methods for evaluating the NSF are presented. Algorithms to compute the NSF are developed for the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar and tested using data from the Lidar In-space Technology Experiment (LITE). OCIS Codes:

Electromagnetic backscattering from freak waves in (1 + 1)-dimensional deep-water

NASA Astrophysics Data System (ADS)

Xie, Tao; Shen, Tao; William, Perrie; Chen, Wei; Kuang, Hai-Lan

2010-05-01

To study the electromagnetic (EM) backscatter characteristics of freak waves at moderate incidence angles, we establish an EM backscattering model for freak waves in (1 + 1)-dimensional deep water. The nonlinear interaction between freak waves and Bragg short waves is considered to be the basic hydrodynamic spectra modulation mechanism in the model. Numerical results suggest that the EM backscattering intensities of freak waves are less than those from the background sea surface at moderate incidence angles. The normalised radar cross sections (NRCSs) from freak waves are highly polarisation dependent, even at low incidence angles, which is different from the situation for normal sea waves; moreover, the NRCS of freak waves is more polarisation dependent than the background sea surface. NRCS discrepancies between freak waves and the background sea surface with using horizontal transmitting horizomtal (HH) polarisation are larger than those using vertical transmitting vertical (VV) polarisation, at moderate incident angles. NRCS discrepancies between freak waves and background sea surface decreases with the increase of incidence angle, in both HH and VV polarisation radars. As an application, in the synthetic-aperture radar (SAR) imaging of freak waves, we suggest that freak waves should have extremely low backscatter NRCSs for the freak wave facet with the strongest slope. Compared with the background sea surface, the freak waves should be darker in HH polarisation echo images than in VV echo images, in SAR images. Freak waves can be more easily detected from the background sea surface in HH polarisation images than in VV polarisation images. The possibility of detection of freak waves at low incidence angles is much higher than at high incidence angles.

Seasonal and interannual variations in total ozone revealed by the Nimbus-4 backscattered ultraviolet experiment

NASA Technical Reports Server (NTRS)

Hilsenrath, E.; Heath, D. F.; Schlesinger, B. M.

1978-01-01

The first two years of Backscattered Ultraviolet (BUV) ozone data from the Nimbus-4 spacecraft were reprocessed. The seasonal variations of total ozone for the period April 1970 to April 1972 are described using daily zonal means to 10 deg latitude zones and a time-latitude cross section. In addition, the BUV data are compared with analyzed Dobson data and with IRIS data also obtained from the Nimbus-4 spacecraft. A harmonic analysis was performed on the daily zonal means. Amplitudes, days of peaks, and percentage of variance were computed for annual and semi-annual waves and for higher harmonics of an annual period for the two years. Asymmetries are found in the annual waves in the two hemispheres, with a subtle interannual difference which may be due to changes in the general circulation. A significant semi-annual component is detected in the tropics for the first year, which appears to result from influences of the annual waves in the two hemispheres.

Investigation of radar backscattering from second-year sea ice

NASA Technical Reports Server (NTRS)

Lei, Guang-Tsai; Moore, Richard K.; Gogineni, S. P.

1988-01-01

The scattering properties of second-year ice were studied in an experiment at Mould Bay in April 1983. Radar backscattering measurements were made at frequencies of 5.2, 9.6, 13.6, and 16.6 GHz for vertical polarization, horizontal polarization and cross polarizations, with incidence angles ranging from 15 to 70 deg. The results indicate that the second-year ice scattering characteristics were different from first-year ice and also different from multiyear ice. The fading properties of radar signals were studied and compared with experimental data. The influence of snow cover on sea ice can be evaluated by accounting for the increase in the number of independent samples from snow volume with respect to that for bare ice surface. A technique for calculating the snow depth was established by this principle and a reasonable agreement has been observed. It appears that this is a usable way to measure depth in snow or other snow-like media using radar.

Observations of Enhanced Radar Backscatter (ERB) from Millstone Hill

NASA Technical Reports Server (NTRS)

Lee, M. C.

1991-01-01

Intense enhancements of the incoherent radar backscatter spectrum from the topside ionosphere were observed with the Millstone Hill UHF radar. Enhancements occurring at the local ion acoustic frequency causing large asymmetries in the measured ion line may be produced by current driven instabilities. These enhancements pose a practical problem for space surveillance systems because their cross section and spectral width are characteristic of satellites. Conversely, their hard target signature complicates the study of naturally occurring ERB events; it is nearly impossible to distinguish them from satellites based on a single measurement. Statistical comparisons of observed coherent echo distributions with predictions from a satellite catalog were used to broadly identify periods of ERB activity. A series of experiments using multiple diagnostics, including satellite instruments, for simultaneous observations have established the association of ERB with large fluxes of soft suprathermal electrons carrying field aligned currents. Zenith data are also presented which show the asymmetric growth of ion acoustic waves directly above Millstone Hill. Details of these results are presented.

Calculated effects of backscattering on skin dosimetry for nuclear fuel fragments.

PubMed

Aydarous, A Sh

2008-01-01

The size of hot particles contained in nuclear fallout ranges from 10 nm to 20 microm for the worldwide weapons fallout. Hot particles from nuclear power reactors can be significantly bigger (100 microm to several millimetres). Electron backscattering from such particles is a prominent secondary effect in beta dosimetry for radiological protection purposes, such as skin dosimetry. In this study, the effect of electron backscattering due to hot particles contamination on skin dose is investigated. These include parameters such as detector area, source radius, source energy, scattering material and source density. The Monte-Carlo Neutron Particle code (MCNP4C) was used to calculate the depth dose distribution for 10 different beta sources and various materials. The backscattering dose factors (BSDF) were then calculated. A significant dependence is shown for the BSDF magnitude upon detector area, source radius and scatterers. It is clearly shown that the BSDF increases with increasing detector area. For high Z scatterers, the BSDF can reach as high as 40 and 100% for sources with radii 0.1 and 0.0001 cm, respectively. The variation of BSDF with source radius, source energy and source density is discussed.

Spatial variability in acoustic backscatter as an indicator of tissue homogenate production in pulsed cavitational ultrasound therapy.

PubMed

Parsons, Jessica E; Cain, Charles A; Fowlkes, J Brian

2007-03-01

Spatial variability in acoustic backscatter is investigated as a potential feedback metric for assessment of lesion morphology during cavitation-mediated mechanical tissue disruption ("histotripsy"). A 750-kHz annular array was aligned confocally with a 4.5 MHz passive backscatter receiver during ex vivo insonation of porcine myocardium. Various exposure conditions were used to elicit a range of damage morphologies and backscatter characteristics [pulse duration = 14 micros, pulse repetition frequency (PRF) = 0.07-3.1 kHz, average I(SPPA) = 22-44 kW/cm2]. Variability in backscatter spatial localization was quantified by tracking the lag required to achieve peak correlation between sequential RF A-lines received. Mean spatial variability was observed to be significantly higher when damage morphology consisted of mechanically disrupted tissue homogenate versus mechanically intact coagulation necrosis (2.35 +/- 1.59 mm versus 0.067 +/- 0.054 mm, p < 0.025). Statistics from these variability distributions were used as the basis for selecting a threshold variability level to identify the onset of homogenate formation via an abrupt, sustained increase in spatially dynamic backscatter activity. Specific indices indicative of the state of the homogenization process were quantified as a function of acoustic input conditions. The prevalence of backscatter spatial variability was observed to scale with the amount of homogenate produced for various PRFs and acoustic intensities.

Tropical Forest Backscatter Anomaly Evident in SeaWinds Scatterometer Morning Overpass Data During 2005 Drought in Amazonia

NASA Astrophysics Data System (ADS)

Frolking, S. E.; Milliman, T.; Palace, M. W.; Wisser, D.; Lammers, R. B.; Fahnestock, M. A.

2010-12-01

A severe drought occurred in many portions of Amazonia in the dry season (June-September) of 2005. We analyzed ten years (7/99-10/09) of SeaWinds active microwave Ku-band backscatter data collected over the Amazon Basin, developing a monthly climatology and monthly anomalies from that climatology in an effort to detect landscape responses to this drought. We compared these to seasonal accumulating water deficit anomalies generated using Tropical Rainfall Monitoring Mission (TRMM) precipitation data (1999-2009) and 100 mm/mo evapotranspirative demand as a water deficit threshold. There was significant interannual variability in monthly mean backscatter only for ascending (early morning) overpass data, and little interannual variability in monthly mean backscatter for descending (late afternoon) overpass data. Strong negative anomalies in both ascending-overpass backscatter and accumulating water deficit developed during July-October 2005, centered on the southwestern Amazon Basin (Acre and western Amazonas states in Brazil; Madre de Dios state in Peru; Pando state in Bolivia). During the 2005 drought, there was a strong spatial correlation between morning overpass backscatter anomalies and water deficit anomalies. We hypothesize that as the drought persisted over several months, the forest canopy was increasingly unable to recover full leaf moisture content over night, and the early morning overpass backscatter data became anomalously low. This is the first reporting of tropical wet forest seasonal drought detection by active microwave scatterometry.

Characterization of Forest Opacity Using Multi-Angular Emission and Backscatter Data

NASA Technical Reports Server (NTRS)

Kurum, Mehmet; O'Neill, Peggy; Lang, Roger H.; Joseph, Alicia T.; Cosh, Michael H.; Jackson, Thomas J.

2010-01-01

This paper discusses the results from a series of field experiments using ground-based L-band microwave active/passive sensors. Three independent approaches are employed to the microwave data to determine vegetation opacity of coniferous trees. First, a zero-order radiative transfer model is fitted to multi-angular microwave emissivity data in a least-square sense to provide "effective" vegetation optical depth. Second, a ratio between radar backscatter measurements with the corner reflector under trees and in an open area is calculated to obtain "measured" tree propagation characteristics. Finally, the "theoretical" propagation constant is determined by forward scattering theorem using detailed measurements of size/angle distributions and dielectric constants of the tree constituents (trunk, branches, and needles). The results indicate that "effective" values underestimate attenuation values compared to both "theoretical" and "measured" values.

Coherent Backscattering and Opposition Effects Observed in Some Atmosphereless Bodies of the Solar System

NASA Technical Reports Server (NTRS)

Dlugach, Zh. M.; Mishchenko, M. I.

2013-01-01

The results of photometric and polarimetric observations carried out for some bright atmosphere-less bodies of the Solar system near the zero phase angle reveal the simultaneous existence of two spectacular optical phenomena, the so-called brightness and polarization opposition effects. In a number of studies, these phenomena were explained by the influence of coherent backscattering. However, in general, the interference concept of coherent backscattering can be used only in the case where the particles are in the far-field zones of each other, i.e., when the scattering medium is rather rarefied. Because of this, it is important to prove rigorously and to demonstrate that the coherent backscattering effect may also exist in densely packed scattering media like regolith surface layers of celestial bodies. From the results of the computer modeling performed with the use of numerically exact solutions of the macroscopic Maxwell equations for discrete random media with different packing densities of particles, we studied the origin and evolution of all the opposition phenomena predicted by the coherent backscattering theory for low-packing-density media. It has been shown that the predictions of this theory remain valid for rather high-packing densities of particles that are typical, in particular, of regolith surfaces of the Solar system bodies. The results allow us to conclude that both opposition effects observed simultaneously in some high-albedo atmosphereless bodies of the Solar system are caused precisely by coherent backscattering of solar light in the regolith layers composed of microscopic particles.

Monte Carlo investigation of backscatter factors for skin dose determination in interventional neuroradiology procedures

NASA Astrophysics Data System (ADS)

Omar, Artur; Benmakhlouf, Hamza; Marteinsdottir, Maria; Bujila, Robert; Nowik, Patrik; Andreo, Pedro

2014-03-01

Complex interventional and diagnostic x-ray angiographic (XA) procedures may yield patient skin doses exceeding the threshold for radiation induced skin injuries. Skin dose is conventionally determined by converting the incident air kerma free-in-air into entrance surface air kerma, a process that requires the use of backscatter factors. Subsequently, the entrance surface air kerma is converted into skin kerma using mass energy-absorption coefficient ratios tissue-to-air, which for the photon energies used in XA is identical to the skin dose. The purpose of this work was to investigate how the cranial bone affects backscatter factors for the dosimetry of interventional neuroradiology procedures. The PENELOPE Monte Carlo system was used to calculate backscatter factors at the entrance surface of a spherical and a cubic water phantom that includes a cranial bone layer. The simulations were performed for different clinical x-ray spectra, field sizes, and thicknesses of the bone layer. The results show a reduction of up to 15% when a cranial bone layer is included in the simulations, compared with conventional backscatter factors calculated for a homogeneous water phantom. The reduction increases for thicker bone layers, softer incident beam qualities, and larger field sizes, indicating that, due to the increased photoelectric crosssection of cranial bone compared to water, the bone layer acts primarily as an absorber of low-energy photons. For neurointerventional radiology procedures, backscatter factors calculated at the entrance surface of a water phantom containing a cranial bone layer increase the accuracy of the skin dose determination.

Monitoring Everglades freshwater marsh water level using L-band synthetic aperture radar backscatter

USGS Publications Warehouse

Kim, Jin-Woo; Lu, Zhong; Jones, John W.; Shum, C.K.; Lee, Hyongki; Jia, Yuanyuan

2014-01-01

The Florida Everglades plays a significant role in controlling floods, improving water quality, supporting ecosystems, and maintaining biodiversity in south Florida. Adaptive restoration and management of the Everglades requires the best information possible regarding wetland hydrology. We developed a new and innovative approach to quantify spatial and temporal variations in wetland water levels within the Everglades, Florida. We observed high correlations between water level measured at in situ gages and L-band SAR backscatter coefficients in the freshwater marsh, though C-band SAR backscatter has no close relationship with water level. Here we illustrate the complementarity of SAR backscatter coefficient differencing and interferometry (InSAR) for improved estimation of high spatial resolution water level variations in the Everglades. This technique has a certain limitation in applying to swamp forests with dense vegetation cover, but we conclude that this new method is promising in future applications to wetland hydrology research.

An analytical model for light backscattering by coccoliths and coccospheres of Emiliania huxleyi.

PubMed

Fournier, Georges; Neukermans, Griet

2017-06-26

We present an analytical model for light backscattering by coccoliths and coccolithophores of the marine calcifying phytoplankter Emiliania huxleyi. The model is based on the separation of the effects of diffraction, refraction, and reflection on scattering, a valid assumption for particle sizes typical of coccoliths and coccolithophores. Our model results match closely with results from an exact scattering code that uses complex particle geometry and our model also mimics well abrupt transitions in scattering magnitude. Finally, we apply our model to predict changes in the spectral backscattering coefficient during an Emiliania huxleyi bloom with results that closely match in situ measurements. Because our model captures the key features that control the light backscattering process, it can be generalized to coccoliths and coccolithophores of different morphologies which can be obtained from size-calibrated electron microphotographs. Matlab codes of this model are provided as supplementary material.

Interior view, looking northeast in computer room OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Interior view, looking northeast in computer room - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Five Receiver Building, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

Interior view, looking south in computer room OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Interior view, looking south in computer room - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Six Receiver Building, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

General view looking northnortheast at antenna array OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

General view looking north-northeast at antenna array - Over-the-Horizon Backscatter Radar Network, Moscow Radar Site Transmit Sector Two Antenna Array, At the end of Steam Road, Moscow, Somerset County, ME

Detail of antenna array, looking northnorthwest OvertheHorizon Backscatter Radar ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail of antenna array, looking north-northwest - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Five Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

General view looking northnortheast at antenna array OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

General view looking north-northeast at antenna array - Over-the-Horizon Backscatter Radar Network, Moscow Radar Site Transmit Sector One Antenna Array, At the end of Steam Road, Moscow, Somerset County, ME

General view of Antenna Array, looking west OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

General view of Antenna Array, looking west - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Six Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

Laser remote sensing of tropospheric aerosol over Southern Ireland using a backscatter Raman LIDAR

NASA Astrophysics Data System (ADS)

Ruth, Albert A.; Acheson, Karen; Apituley, Arnoud; Chaikovsky, Anatoli; Nicolae, Doina; Ortiz-Amezcua, Pablo; Stoyanov, Dimitar; Trickl, Thomas

2016-04-01

Raman backscatter coefficients, extinction coefficients and lidar ratios were measured with a ground based Raman lidar system at University College Cork, Ireland, during the periods of July 2012 - August 2012, April 2013 - December 2013 and March 2014 - May 2014. Statistical analysis of these parameters in this time provided information about seasonal effects of Raman backscatter coefficients and the altitude of the top of the planetary boundary layer. The mean of the altitude of the top of the planetary boundary layer over these time periods is 950 ± 302 m. The values are larger in summer, 1206 ± 367 m, than in winter, 735 m. The altitude of the top of the planetary boundary layer measured at Cork is lower than most EARLINET stations. Raman backscatter coefficients above and altitude of 2 km are highest in summer and spring where the values are greater than 0.28 Mm-1 sr-1. Winter values of Raman backscatter coefficient are less than 0.06 Mm-1 sr-1. These seasonal effects are consistent with most EARLINET stations. Large aerosol loads were detected in July 2013 due to a Canadian forest fire event. HYSPLIT air-mass back trajectory models were used to trace the origin of the detected aerosol layers. The aerosol forecast model, MACC, was used to further investigate and verify the propagation of the smoke. The Lidar ratio values and Klett and Raman backscatter coefficients at Cork, for the 4th July, the 7th to 9th of July and the 11th July were compared with observations at Cabauw, Minsk, Granada, Bucharest, Sofia and Garmisch. Lidar ratio values for the smoke detected at Cork were determined to be between 33 sr and 62 sr. The poster will discuss the seasonal changes of Raman backscatter coefficients and the altitude of the top of the planetary boundary layer at Cork. An investigation of a Canadian forest fire event measured at Cork will be compared with other data from the EARLINET database.

Joint learning of ultrasonic backscattering statistical physics and signal confidence primal for characterizing atherosclerotic plaques using intravascular ultrasound.

PubMed

Sheet, Debdoot; Karamalis, Athanasios; Eslami, Abouzar; Noël, Peter; Chatterjee, Jyotirmoy; Ray, Ajoy K; Laine, Andrew F; Carlier, Stephane G; Navab, Nassir; Katouzian, Amin

2014-01-01

Intravascular Ultrasound (IVUS) is a predominant imaging modality in interventional cardiology. It provides real-time cross-sectional images of arteries and assists clinicians to infer about atherosclerotic plaques composition. These plaques are heterogeneous in nature and constitute fibrous tissue, lipid deposits and calcifications. Each of these tissues backscatter ultrasonic pulses and are associated with a characteristic intensity in B-mode IVUS image. However, clinicians are challenged when colocated heterogeneous tissue backscatter mixed signals appearing as non-unique intensity patterns in B-mode IVUS image. Tissue characterization algorithms have been developed to assist clinicians to identify such heterogeneous tissues and assess plaque vulnerability. In this paper, we propose a novel technique coined as Stochastic Driven Histology (SDH) that is able to provide information about co-located heterogeneous tissues. It employs learning of tissue specific ultrasonic backscattering statistical physics and signal confidence primal from labeled data for predicting heterogeneous tissue composition in plaques. We employ a random forest for the purpose of learning such a primal using sparsely labeled and noisy samples. In clinical deployment, the posterior prediction of different lesions constituting the plaque is estimated. Folded cross-validation experiments have been performed with 53 plaques indicating high concurrence with traditional tissue histology. On the wider horizon, this framework enables learning of tissue-energy interaction statistical physics and can be leveraged for promising clinical applications requiring tissue characterization beyond the application demonstrated in this paper. Copyright © 2013 Elsevier B.V. All rights reserved.

Monte Carlo simulation of MOSFET dosimeter for electron backscatter using the GEANT4 code.

PubMed

Chow, James C L; Leung, Michael K K

2008-06-01

The aim of this study is to investigate the influence of the body of the metal-oxide-semiconductor field effect transistor (MOSFET) dosimeter in measuring the electron backscatter from lead. The electron backscatter factor (EBF), which is defined as the ratio of dose at the tissue-lead interface to the dose at the same point without the presence of backscatter, was calculated by the Monte Carlo simulation using the GEANT4 code. Electron beams with energies of 4, 6, 9, and 12 MeV were used in the simulation. It was found that in the presence of the MOSFET body, the EBFs were underestimated by about 2%-0.9% for electron beam energies of 4-12 MeV, respectively. The trend of the decrease of EBF with an increase of electron energy can be explained by the small MOSFET dosimeter, mainly made of epoxy and silicon, not only attenuated the electron fluence of the electron beam from upstream, but also the electron backscatter generated by the lead underneath the dosimeter. However, this variation of the EBF underestimation is within the same order of the statistical uncertainties as the Monte Carlo simulations, which ranged from 1.3% to 0.8% for the electron energies of 4-12 MeV, due to the small dosimetric volume. Such small EBF deviation is therefore insignificant when the uncertainty of the Monte Carlo simulation is taken into account. Corresponding measurements were carried out and uncertainties compared to Monte Carlo results were within +/- 2%. Spectra of energy deposited by the backscattered electrons in dosimetric volumes with and without the lead and MOSFET were determined by Monte Carlo simulations. It was found that in both cases, when the MOSFET body is either present or absent in the simulation, deviations of electron energy spectra with and without the lead decrease with an increase of the electron beam energy. Moreover, the softer spectrum of the backscattered electron when lead is present can result in a reduction of the MOSFET response due to stronger

Simulation of L-band and HH microwave backscattering from coniferous forest stands - A comparison with SIR-B data

NASA Technical Reports Server (NTRS)

Sun, Guo-Qing; Simonett, David S.

1988-01-01

SIR-B images of the Mt. Shasta region of northern California are used to evaluate a composite L-band HH backscattering model of coniferous forest stands. It is found that both SIR-B and simulated backscattering coefficients for eight stands studied have similar trends and relations to average tree height and average number of trees per pixel. Also, the dispersion and distribution of simulated backscattering coefficients from each stand broadly match SIR-B data from the same stand. Although the limited quality and quantity of experimental data makes it difficult to draw any strong conclusions, the comparisons indicate that a stand-based L-band HH composite model seems promising for explaining backscattering features.

The Growth and Decay of Equatorial Backscatter Plumes.

DTIC Science & Technology

1980-02-01

spatially connected to bottomside backscatter, a feature noted in Jica- marca radar observations that led Woodman and La Hoz (1976) to speculate that...described in Section Ill-B, this pattern of plume growth resembles the "C-shaped" and "fishtail" patterns found in Jica- marca radar RTI displays of 50-MHz

The Backscattering Phase Function for a Sphere with a Two-Scale Relief of Rough Surface

NASA Astrophysics Data System (ADS)

Klass, E. V.

2017-12-01

The backscattering of light from spherical surfaces characterized by one and two-scale roughness reliefs has been investigated. The analysis is performed using the three-dimensional Monte-Carlo program POKS-RG (geometrical-optics approximation), which makes it possible to take into account the roughness of objects under study by introducing local geometries of different levels. The geometric module of the program is aimed at describing objects by equations of second-order surfaces. One-scale roughness is set as an ensemble of geometric figures (convex or concave halves of ellipsoids or cones). The two-scale roughness is modeled by convex halves of ellipsoids, with surface containing ellipsoidal pores. It is shown that a spherical surface with one-scale convex inhomogeneities has a flatter backscattering phase function than a surface with concave inhomogeneities (pores). For a sphere with two-scale roughness, the dependence of the backscattering intensity is found to be determined mostly by the lower-level inhomogeneities. The influence of roughness on the dependence of the backscattering from different spatial regions of spherical surface is analyzed.

Advancements in Electromagnetic Wave Backscattering Simulations: Applications in Active Lidar Remote Sensing Involving Aerosols

NASA Astrophysics Data System (ADS)

Bi, L.

2016-12-01

Atmospheric remote sensing based on the Lidar technique fundamentally relies on knowledge of the backscattering of light by particulate matters in the atmosphere. This talk starts with a review of the current capabilities of electromagnetic wave scattering simulations to determine the backscattering optical properties of irregular particles, such as the backscatterer and depolarization ratio. This will be followed by a discussion of possible pitfalls in the relevant simulations. The talk will then be concluded with reports on the latest advancements in computational techniques. In addition, we summarize the laws of the backscattering optical properties of aerosols with respect to particle geometries, particle sizes, and mixing rules. These advancements will be applied to the analysis of the Lidar observation data to reveal the state and possible microphysical processes of various aerosols.

Exploring the Globe: Collecting and Sharing Data to Make a Difference.

ERIC Educational Resources Information Center

Singletary, Ted J.; Jordan, J. Richard

1996-01-01

Describes the Global Learning and Observations to Benefit the Environment (GLOBE) program that aims at involving K-12 students in significant data collection and analysis which are then entered into a widely accessible World Wide Web site for use by other students, teachers, and researchers. Provides an invaluable base for developing a better…

Oblique view to south OvertheHorizon Backscatter Radar Network, Mountain ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Oblique view to south - Over-the-Horizon Backscatter Radar Network, Mountain Home Air Force Operations Building, On Desert Street at 9th Avenue Mountain Home Air Force Base, Mountain Home, Elmore County, ID

Detail of antenna tower structure, looking northnorthwest OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey