Comparison of Echo 7 field line length measurements to magnetospheric model predictions

International Nuclear Information System (INIS)

Nemzek, R.J.; Winckler, J.R.; Malcolm, P.R.

1992-01-01

The Echo 7 sounding rocket experiment injected electron beams on central tail field lines near L = 6.5. Numerous injections returned to the payload as conjugate echoes after mirroring in the southern hemisphere. The authors compare field line lengths calculated from measured conjugate echo bounce times and energies to predictions made by integrating electron trajectories through various magnetospheric models: the Olson-Pfitzer Quiet and Dynamic models and the Tsyganenko-Usmanov model. Although Kp at launch was 3-, quiet time magnetic models est fit the echo measurements. Geosynchronous satellite magnetometer measurements near the Echo 7 field lies during the flight were best modeled by the Olson-Pfitzer Dynamic Model and the Tsyganenko-Usmanov model for Kp = 3. The discrepancy between the models that best fit the Echo 7 data and those that fit the satellite data was most likely due to uncertainties in the small-scale configuration of the magnetospheric models. The field line length measured by the conjugate echoes showed some temporal variation in the magnetic field, also indicated by the satellite magnetometers. This demonstrates the utility an Echo-style experiment could have in substorm studies

Echo 7: Magnetospheric properties determined by artificial electron beams

International Nuclear Information System (INIS)

Nemzek, R.J.

1990-01-01

The sounding rocket Echo 7 was launched from the Poker Flat Research Range. An on-board accelerator injected high-power electron beams into the magnetospheric tail near L = 6.5. After mirroring at the southern conjugate point, about 20 percent of the initial beam electrons returned to the North as Conjugate Echoes, where detectors (scintillators and spectrometers) on four subpayloads measured their energy and bounce time. The other 80 percent of the beam was pitch angle diffused by wave near the equatorial plane either into the conjugate atmosphere or up to mirror points above the payload. Comparison of measured values to calculations showed that the actual magnetosphere during the flight was well-described by the Tsyganenko-Usmanov model magnetosphere with a Kp value of 2- or 2+. Analysis of echo energies yielded values for the highly variable magnetospheric convection electric field

The utility of bathymetric echo sounding data in modelling benthic impacts using NewDEPOMOD driven by an FVCOM model.

Science.gov (United States)

Rochford, Meghan; Black, Kenneth; Aleynik, Dmitry; Carpenter, Trevor

2017-04-01

The Scottish Environmental Protection Agency (SEPA) are currently implementing new regulations for consenting developments at new and pre-existing fish farms. Currently, a 15-day current record from multiple depths at one location near the site is required to run DEPOMOD, a depositional model used to determine the depositional footprint of waste material from fish farms, developed by Cromey et al. (2002). The present project involves modifying DEPOMOD to accept data from 3D hydrodynamic models to allow for a more accurate representation of the currents around the farms. Bathymetric data are key boundary conditions for accurate modelling of current velocity data. The aim of the project is to create a script that will use the outputs from FVCOM, a 3D hydrodynamic model developed by Chen et al. (2003), and input them into NewDEPOMOD (a new version of DEPOMOD with more accurately parameterised sediment transport processes) to determine the effect of a fish farm on the surrounding environment. This study compares current velocity data under two scenarios; the first, using interpolated bathymetric data, and the second using bathymetric data collected during a bathymetric echo sounding survey of the site. Theoretically, if the hydrodynamic model is of high enough resolution, the two scenarios should yield relatively similar results. However, the expected result is that the survey data will be of much higher resolution and therefore of better quality, producing more realistic velocity results. The improvement of bathymetric data will also improve sediment transport predictions in NewDEPOMOD. This work will determine the sensitivity of model predictions to bathymetric data accuracy at a range of sites with varying bathymetric complexity and thus give information on the potential costs and benefits of echo sounding survey data inputs. Chen, C., Liu, H. and Beardsley, R.C., 2003. An unstructured grid, finite-volume, three-dimensional, primitive equations ocean model

Application of surface geophysics to ground-water investigations

Science.gov (United States)

Zohdy, Adel A.R.; Eaton, Gordon P.; Mabey, Don R.

1974-01-01

This manual reviews the standard methods of surface geophysics applicable to ground-water investigations. It covers electrical methods, seismic and gravity methods, and magnetic methods. The general physical principles underlying each method and its capabilities and limitations are described. Possibilities for non-uniqueness of interpretation of geophysical results are noted. Examples of actual use of the methods are given to illustrate applications and interpretation in selected geohydrologic environments. The objective of the manual is to provide the hydrogeologist with a sufficient understanding of the capabilities, imitations, and relative cost of geophysical methods to make sound decisions as to when to use of these methods is desirable. The manual also provides enough information for the hydrogeologist to work with a geophysicist in designing geophysical surveys that differentiate significant hydrogeologic changes.

Investigations of the form and flow of ice sheets and glaciers using radio-echo sounding

Energy Technology Data Exchange (ETDEWEB)

Dowdeswell, J A; Evans, S [Scott Polar Research Institute, University of Cambridge, Cambridge CB2 1ER (United Kingdom)

2004-10-01

Radio-echo sounding (RES), utilizing a variety of radio frequencies, was developed to allow glaciologists to measure the thickness of ice sheets and glaciers. We review the nature of electromagnetic wave propagation in ice and snow, including the permittivity of ice, signal attenuation and volume scattering, along with reflection from rough and specular surfaces. The variety of instruments used in RES of polar ice sheets and temperate glaciers is discussed. The applications and insights that a knowledge of ice thickness, and the wider nature of the form and flow of ice sheets, provides are also considered. The thickest ice measured is 4.7 km in East Antarctica. The morphology of the Antarctic and Greenland ice sheets, and many of the smaller ice caps and glaciers of the polar regions, has been investigated using RES. These findings are being used in three-dimensional numerical models of the response of the cryosphere to environmental change. In addition, the distribution and character of internal and basal reflectors within ice sheets contains information on, for example, ice-sheet layering and its chrono-stratigraphic significance, and has enabled the discovery and investigation of large lakes beneath the Antarctic Ice Sheet. Today, RES from ground-based and airborne platforms remains the most effective tool for measuring ice thickness and internal character.

Ionospheric Irregularities at Mars Probed by MARSIS Topside Sounding

Science.gov (United States)

Harada, Y.; Gurnett, D. A.; Kopf, A. J.; Halekas, J. S.; Ruhunusiri, S.

2018-01-01

The upper ionosphere of Mars contains a variety of perturbations driven by solar wind forcing from above and upward propagating atmospheric waves from below. Here we explore the global distribution and variability of ionospheric irregularities around the exobase at Mars by analyzing topside sounding data from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board Mars Express. As irregular structure gives rise to off-vertical echoes with excess propagation time, the diffuseness of ionospheric echo traces can be used as a diagnostic tool for perturbed reflection surfaces. The observed properties of diffuse echoes above unmagnetized regions suggest that ionospheric irregularities with horizontal wavelengths of tens to hundreds of kilometers are particularly enhanced in the winter hemisphere and at high solar zenith angles. Given the known inverse dependence of neutral gravity wave amplitudes on the background atmospheric temperature, the ionospheric irregularities probed by MARSIS are most likely associated with plasma perturbations driven by atmospheric gravity waves. Though extreme events with unusually diffuse echoes are more frequently observed for high solar wind dynamic pressures during some time intervals, the vast majority of the diffuse echo events are unaffected by varying solar wind conditions, implying limited influence of solar wind forcing on the generation of ionospheric irregularities. Combination of remote and in situ measurements of ionospheric irregularities would offer the opportunity for a better understanding of the ionospheric dynamics at Mars.

Results from the University of Calgary environmental geophysics test range

Energy Technology Data Exchange (ETDEWEB)

Duckworth, K; Lawton, D.C.; Juigalli, J; Parry, D. [Calgary Univ., AB (Canada). Dept. of Geology and Geophysics

1995-12-31

The Spy Hill Research Farm, operated by the University of Calgary as a test range site where geophysical equipment and methods related to environmental monitoring can be operated under controlled conditions, was described. The site is used by students in the geophysics courses offered at the University, but it is also intended to be available to other users for equipment tests. The site is underlain by glacial gravels and clays which reach thicknesses in excess of 30 m. Surveys of the site have been completed with the following geophysical systems: Geonics EM-31 and EM-34; Apex Max-Min; Huntec Mk4 IP with Phoenix IP-T1 transmitter; Geometrics Proton Magnetometer; McPhar vertical field Fluxgate magnetometer; Androtex TDR6 IP with Phoenix IP-T1 transmitter; Geometrics 12 channel refraction seismic system; and Pulse Echo Ground Penetrating Radar. The site has proved to be well suited to serve as a test range. The addition of yet more features to the site is being planned.

Speed of sound measurements of liquid C1–C4 alkanols

International Nuclear Information System (INIS)

Dávila, María J.; Gedanitz, Holger; Span, Roland

2016-01-01

Highlights: • Speeds of sound in alkanols were measured in a wide temperature and pressure range. • A pulse-echo method with a double path type sensor was employed. • A double polynomial equation was used to fit the experimental speed of sound data. • The accurate results were compared with available literature sources. - Abstract: Speed of sound measurements were made in methanol, ethanol, propan-1-ol, and butan-1-ol in the temperature range from (253.15 to 353.15) K at pressures up to 30 MPa by use of a pulse-echo method with a double path type sensor. The expanded overall uncertainty (k = 2) in speed of sound measurements are estimated to be 0.026% for methanol, 0.03% for ethanol, 0.013% for propan-1-ol and 0.01% for butan-1-ol. A double polynomial equation for the speed of sound with inputs of temperature and pressure has been fitted from the experimental results. These were compared with available literature sources and fundamental equations of state, showing good agreement among them to comparable alcohol purities and experimental uncertainties.

Testing how geophysics can reduce the uncertainty of groundwater model predictions

DEFF Research Database (Denmark)

Christensen, Nikolaj Kruse; Christensen, Steen; Ferre, Ty

2014-01-01

Geophysical data are increasingly used to construct groundwater models. Such data are collected at lower cost and much higher density than the traditionally used geological, hydraulic, and hydrological data. The geophysical data are often inverted independently and used together with geological......, respectively. There is also complete flexibility in the choice of relationships between hydraulic and geophysical properties. Noise can be added to the synthetic hydrologic and geophysical datasets and these exhaustive data sets can be down sampled to represent realistic data sets of varying measurement...... with and covered by layered glaciofluvial and glacial deposits. The hydrological data consist of 35 hydraulic head measurements and one river discharge measurement, while the geophysical data consist of 77 TEM soundings. The data are inverted sequentially and jointly. Through this example, we highlight the value...

Vespertilionid bats control the width of their biosonar sound beam dynamically during prey pursuit

DEFF Research Database (Denmark)

Jakobsen, Lasse; Surlykke, Annemarie

2010-01-01

Animals using sound for communication emit directional signals, focusing most acoustic energy in one direction. Echolocating bats are listening for soft echoes from insects. Therefore, a directional biosonar sound beam greatly increases detection probability in the forward direction and decreases...

Hydro geophysical Investigation for Groundwater Development at ...

African Journals Online (AJOL)

ADOWIE PERE

Environ. Manage. May. 2017. Vol. 21 (3) 527-535. Full-text Available Online at ... is of equal importance with the air we breathe in ... numerical modeling solutions. The electrical geophysical survey method is the .... VES data at twelve (12) sounding points as shown in figure 2; five along traverse one; two along traverse two,.

Depth study of insular shelf electric sounding Adelaida anomaly (Rivera)

International Nuclear Information System (INIS)

Cicalese, H.

1983-01-01

In the framework of the Uranium prospecting programme, the DINAMIGE geophysical equipment have made a study. It was about the depth of insular shelf electric sounding on the anomalies zone of Adelaida. This equipment carried out a study of the following subjects: geographical location, geologic framework, geophysical intervention, developed works, methods and material and results

The detection of 'virtual' objects using echoes by humans: Spectral cues.

Science.gov (United States)

Rowan, Daniel; Papadopoulos, Timos; Archer, Lauren; Goodhew, Amanda; Cozens, Hayley; Lopez, Ricardo Guzman; Edwards, David; Holmes, Hannah; Allen, Robert

2017-07-01

Some blind people use echoes to detect discrete, silent objects to support their spatial orientation/navigation, independence, safety and wellbeing. The acoustical features that people use for this are not well understood. Listening to changes in spectral shape due to the presence of an object could be important for object detection and avoidance, especially at short range, although it is currently not known whether it is possible with echolocation-related sounds. Bands of noise were convolved with recordings of binaural impulse responses of objects in an anechoic chamber to create 'virtual objects', which were analysed and played to sighted and blind listeners inexperienced in echolocation. The sounds were also manipulated to remove cues unrelated to spectral shape. Most listeners could accurately detect hard flat objects using changes in spectral shape. The useful spectral changes for object detection occurred above approximately 3 kHz, as with object localisation. However, energy in the sounds below 3 kHz was required to exploit changes in spectral shape for object detection, whereas energy below 3 kHz impaired object localisation. Further recordings showed that the spectral changes were diminished by room reverberation. While good high-frequency hearing is generally important for echolocation, the optimal echo-generating stimulus will probably depend on the task. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Testing of wooden construction elements with ultrasonic echo technique and x-ray

International Nuclear Information System (INIS)

Hasenstab, A.; Krause, M.; Osterloh, K.

2008-01-01

Damages inside of wooden construction components (e.g. interior rot) or at inaccessible surfaces represent a special problem, since they are difficult to recognize from the outside, they can even cause a sudden failure of the component. As a result the research, it could be proved that ultrasonic echo technique can be used on wood both with longitudinal and transverse waves. Further more the different influences of the wood fibres on the sound velocity of the longitudinal and transverse waves is pointed out on the basis results of measurements. The efficiency of the ultrasonic echo technique is shown on wooden specimens. The combination of ultrasonic echo technique and radiography resulted in a very substantial reduction of possible misinterpretations of damage. There it is possible to detect the damage from the undamaged side of the specimen by ultrasound echo. The spread of the damage can be obtained with mobile x-ray measurements. Finally the results show, that ultrasonic methods are more sensitive starting decay and cracks parallel to the surface.

Speed of sound in biodiesel produced by low power ultrasound

Science.gov (United States)

Oliveira, P. A.; Silva, R. M. B.; Morais, G. C.; Alvarenga, A. V.; Costa-Felix, R. P. B.

2018-03-01

The quality control of the biodiesel produced is an important issue to be addressed for every manufacturer or retailer. The speed of sound is a property that has an influence on the quality of the produced fuel. This work presents the evaluation about the speed of sound in biodiesel produced with the aid of low power ultrasound in the frequencies of 1 MHz and 3 MHz. The speed of sound was measured by pulse-echo technique. The ultrasonic frequency used during reaction affects the speed of sound in biodiesel. The larger expanded uncertainty for adjusted curve was 4.9 m.s-1.

An approach towards solving refraction problems in EM1002 multi-beam echo-sounder system

Digital Repository Service at National Institute of Oceanography (India)

Fernandes, W.A.

Multi-beam echo-sounding is the technique in which multiple beams of acoustic in nature are sent down to seabed and upon reflection, they are received back and processed to give depths values. The report is focused to give a brief idea about EM1002...

Electromagnetic sounding of the Earth's interior

CERN Document Server

Spichak, Viacheslav V

2015-01-01

Electromagnetic Sounding of the Earth's Interior 2nd edition provides a comprehensive up-to-date collection of contributions, covering methodological, computational and practical aspects of Electromagnetic sounding of the Earth by different techniques at global, regional and local scales. Moreover, it contains new developments such as the concept of self-consistent tasks of geophysics and , 3-D interpretation of the TEM sounding which, so far, have not all been covered by one book. Electromagnetic Sounding of the Earth's Interior 2nd edition consists of three parts: I- EM sounding methods, II- Forward modelling and inversion techniques, and III - Data processing, analysis, modelling and interpretation. The new edition includes brand new chapters on Pulse and frequency electromagnetic sounding for hydrocarbon offshore exploration. Additionally all other chapters have been extensively updated to include new developments. Presents recently developed methodological findings of the earth's study, including seism...

Comparison of multi-echo and single-echo gradient-recalled echo sequences for SPIO-enhanced Liver MRI at 3 T

International Nuclear Information System (INIS)

Choi, J.S.; Kim, M.-J.; Kim, J.H.; Choi, J.-Y.; Chung, Y.E.; Park, M.-S.; Kim, K.W.

2010-01-01

Aim: To assess the utility of a T2*-weighted, multi-echo data imaging combination sequenced on superparamagnetic iron oxide (SPIO)-enhanced liver magnetic resonance imaging (MRI) using a 3 T system. Materials and methods: Fifty patients underwent SPIO-enhanced MRI at 3 T using T2*-weighted, single-echo, gradient-recalled echo (GRE) sequences [fast imaging with steady precession; repetition time (TR)/echo time (TE), 126 ms/9 ms; flip angle, 30 o ] and multi-echo GRE (multi-echo data image combination) sequences (TR/TE, 186 ms/9 ms; flip angle, 30 o ). Three radiologists independently reviewed the images in a random order. The sensitivity and accuracy for the detection of focal hepatic lesions (a total of 76 lesions in 33 patients; 48 solid lesions, 28 non-solid lesions) were compared by analysing the area under the receiver operating characteristic curves. Image artefacts (flow artefacts, susceptibility artefacts, dielectric artefacts, and motion artefacts), lesion conspicuity, and overall image quality were evaluated according to a four-point scale: 1, poor; 2, fair; 3, good; 4, excellent. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the lesions were compared. Results: Image artefacts were more frequent with single-echo GRE (p < 0.05). The mean scale of image quality assessment for flow, susceptibility, dielectric, and motion artefacts were 2.76, 3.13, 3.42, and 2.89 with singe-echo, respectively, compared with 3.47, 3.43, 3.47, and 3.39, respectively, with multi-echo GRE. There was no significant difference in lesion conspicuity between single-echo (3.15) and multi-echo (3.30) GRE sequences. The overall image quality was significantly (p < 0.05) better with multi-echo (3.37) than with single-echo GRE (2.89). The mean SNR and CNR of the lesions were significantly (p < 0.05) higher on multi-echo (79 ± 23 and 128 ± 59, respectively) images than on single-echo (38 ± 11 and 102 ± 44, respectively) images. Lesion detection accuracy and

Ice sheet anisotropy measured with polarimetric ice sounding radar

DEFF Research Database (Denmark)

Dall, Jørgen

2010-01-01

For polar ice sheets, valuable stress and strain information can be deduced from crystal orientation fabrics (COF) and their prevailing c-axis alignment. Polarimetric radio echo sounding is a promising technique to measure the anisotropic electromagnetic propagation and reflection properties asso...

Characteristics of Sounds Emitted During High-Resolution Marine Geophysical Surveys

Science.gov (United States)

2016-03-24

Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law , no person shall be...marine transportation , oil and gas, marine mineral, and renewable energy projects. In particular, geophysical surveys support infrastructure siting...sand resource delineation, geomorphic characterization, environmental monitoring, archaeological resource identification, and mapping of shallow

Echo

Energy Technology Data Exchange (ETDEWEB)

Harvey, Dustin Yewell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-01-25

This document is a white paper marketing proposal for Echo™ is a data analysis platform designed for efficient, robust, and scalable creation and execution of complex workflows. Echo’s analysis management system refers to the ability to track, understand, and reproduce workflows used for arriving at results and decisions. Echo improves on traditional scripted data analysis in MATLAB, Python, R, and other languages to allow analysts to make better use of their time. Additionally, the Echo platform provides a powerful data management and curation solution allowing analysts to quickly find, access, and consume datasets. After two years of development and a first release in early 2016, Echo is now available for use with many data types in a wide range of application domains. Echo provides tools that allow users to focus on data analysis and decisions with confidence that results are reported accurately.

High-Resolution Digitization of the Film Archive of SPRI/NSF/TUD Radar Sounding of the Antarctic Ice Sheet

Science.gov (United States)

Schroeder, D. M.; Dowdeswell, J. A.; Mackie, E. J.; Vega, K. I.; Emmons, J. R.; Winstein, K.; Bingham, R. G.; Benham, T. J.

2017-12-01

The airborne radio echo sounding data collected during the SPRI/NSF/TUD surveys of the Antarctic Ice Sheet in the late nineteen sixties and early seventies were recorded on a combination of 35mm and super-8 mm black-and-white optical film. These data represent the oldest extant continent-scale geophysical observations of ice thickness, internal layering and conditions beneath the Antarctic Ice Sheet. As such, when compared with modern radar sounding observations, they offer a unique opportunity to investigate temporal changes in ice sheet conditions across half a century. However, the storage of these data on film, paper-prints, and scans of those prints have made such comparison at the full radiometric and geometric resolution of the data difficult. To address this challenge, we utilized a state-of-the-art high-resolution Hollywood film scanning system to digitize the entire SPRI/NSF/TUD optical film archive. This has resulted in over two million digital images with information at the full spatial and brightness-level resolution of the original film. We present the process and results of this scanning as well as the current progress in formatting, registering, and positioning these data for release and use by the wider radio glaciological community. We also discuss the glaciological insights enabled by this effort.

The University of Texas Institute for Geophysics Marine Geology and Geophysics Field Course

Science.gov (United States)

Duncan, D.; Davis, M. B.; Goff, J. A.; Gulick, S. P. S.; McIntosh, K. D.; Saustrup, S., Sr.

2014-12-01

The University of Texas Institute for Geophysics, part of the Jackson School of Geosciences, annually offers a three-week marine geology and geophysics field course during the spring-summer intersession. The course provides hands-on instruction and training for graduate and upper-level undergraduate students in high-resolution seismic reflection, CHIRP sub-bottom profiling, multibeam bathymetry, sidescan sonar, several types of sediment coring, grab sampling, and the sedimentology of resulting seabed samples. Students participate in an initial three days of classroom instruction designed to communicate geological context of the field area along with theoretical and technical background on each field method. The class then travels to the Gulf Coast for a week of at-sea field work. Our field sites at Port Aransas, and Galveston, TX, and Grand Isle, LA, provide ideal locations for students to investigate coastal processes of the Gulf Coast and continental shelf through application of geophysical techniques in an exploratory mode. At sea, students assist with survey design and instrumentation set up while learning about acquisition parameters, data quality control, trouble-shooting, and safe instrument deployment and retrieval. In teams of four, students work in onshore field labs preparing sediment samples for particle size analysis and data processing. During the course's final week, teams return to the classroom where they integrate, interpret, and visualize data in a final project using industry-standard software such as Echos, Landmark, Caris, and Fledermaus. The course concludes with a series of final presentations and discussions in which students examine geologic history and/or sedimentary processes represented by the Gulf Coast continental shelf with academic and industry supporters. Students report a greater understanding of marine geology and geophysics through the course's intensive, hands-on, team approach and low instructor to student ratio (sixteen

Depth study of insular shelf electric sounding in the Puntas de Abrojal anomaly

International Nuclear Information System (INIS)

Cicalese, H.

1983-01-01

In the framework of the Uranium prospecting Programme, a geophysics team composed by BRGM and DINAMIGE workers were carried out an study about of insular shelf electric sounding on the Puntas de Abrojal area.A geographical location, geologic framework, geophysical survey and methods, materials and results were given

Geophysical anomalies associated with Imjin River Belt (IRB) in the middle Korean Peninsula revealed by geomagnetic depth sounding and seismological data

Science.gov (United States)

Yang, J.; Choi, H.; Noh, M.; Im, C.

2012-12-01

Imjin River Belt (IRB), located in the middle of the Korean Peninsula, has been one of long-standing geological issues because it is a very important tectonic link to understand a tectonic evolution of north-eastern Asia including China, Korea and Japan. Although the IRB has been considered as an extension of collision belt between the North China Block (NCB) and South China Block (SCB), there is little geophysical observation or study on this issue. In recent, we compiled a new induction arrow map for the Korean Peninsula, on the basis of long-period magneto-telluric (MT) data and the geomagnetic depth sounding data performed since the late 1990's. This newly compiled map has finer spatial resolution expecially in the middle area of the peninsula, which helps us to present the geophysical evidence that the IRB is the continuation or extension of the collision belt to the peninsula. The overall pattern of induction arrows in the peninsula appears to indicate a northwest-southeast direction, which is well-known 'sea effect' by the surrounding seas. However, the results of observations in the middle of the peninsula distinctly show an anomalous pattern around the IRB, which can not be explained only by the surrounding seas. This anomalous pattern may be attributed to enhanced conductivity associated with tectonic events that Imjin River Belt has experienced. The 3-D electromagnetic modeling results, considering both surrounding seas and enhanced conductivity of the IRB, explain well the anomalous observations around the IRB. Furthermore, recent seismological study demonstrates that focal mechanism around the IRB is mainly normal faulting event, which may be interpreted as the reactivation of paleo structures that are related to the post collisional lithospheric delamination. All the geophysical evidences convince us that the IRB is an extension of the collision belt between the NCB and SCB to the peninsula.

Electron ECHO 6: a study by particle detectors of electrons artificially injected into the magnetosphere

International Nuclear Information System (INIS)

Malcolm, P.R.

1986-01-01

The ECHO-6 sounding rocket was launched from the Poke Flat Research Range, Alaska on 30 March 1983. A Terrier-Black Brant launch vehicle carried the payload on a northward trajectory over an auroral arc and to an apogee of 216 kilometers. The primary objective of the ECHO-6 experiment was to evaluate electric fields, magnetic fields, and plasma processes in the distant magnetosphere by injecting electron beams in the ionosphere and observing conjugate echoes. The experiment succeeded in injection 10-36 keV beams during the existence of a moderate growth-phase aurora, an easterly electrojet system, and a pre-midnight inflation condition of the magnetosphere. The ECHO-6 payload system consisted of an accelerator MAIN payload, a free-flying Plasma Diagnostics Package (PDP), and four rocket-propelled Throw Away Detectors (TADs). The PDP was ejected from the MAIN payload to analyze electric fields, plasma particles, energetic electrons, and photometric effects produced by beam injections. The TADs were ejected from the MAIN payload in a pattern to detect echoes in the conjugate echo region south of the beam-emitting MAIN payload. The TADs reached distances exceeding 3 kilometers from the MAIN payload and made measurements of the ambient electrons by means of solid-state detectors and electrostatic analyzers

Sustainable urban development and geophysics

Science.gov (United States)

Liu, Lanbo; Chan, L. S.

2007-09-01

development and geophysics' in Journal of Geophysics and Engineering is a response to the call for the development of novel geophysical techniques especially applicable to city settings. It consists of 11 papers which are selected and expanded from a collection of papers presented to the special sessions on 'Sustainable Urban Development and Geophysics' (U14A, U15A, and U41B) in the Union section of the Western Pacific Geophysics Meeting held in Beijing, China, on 22-27 July 2006 [3]. This indicates that new and innovative geophysical applications in urban settings have emerged, and these innovations may be potentially useful for the planning, implementation, and maintenance of urban infrastructure systems. These 11 research papers can be divided into three groups: (1) geophysics and urban infrastructure; (2) geophysics and urban environment; and (3) geophysical investigations associated with geological hazards. The first group of papers focuses on urban infrastructure. Fred Stumm et al reported a geohydrologic assessment of fractured crystalline bedrock with borehole radar in Manhattan, New York in preparation for the construction of a new water tunnel. Using GPR, Xie et al conducted a quality control study of the walls of the river-crossing highway tunnel in Shanghai. For the same purpose, S Liu et al investigated the effect of concrete cracks on GPR signatures using a numerical simulation technique. Sun et al, using seismic surface waves, investigated road beds and the degree of weathering of the marble fence in the Forbidden City, Beijing. In the second group of papers, using a numerical simulation technique, L Liu et al studied the effect of a building coordinate error on sound wave propagation with the aim of locating sound sources in urban settings. Chan et al studied the abundance of radio elements in weathered igneous bedrock in Hong Kong for the purpose of the promotion of public health in the urban environment. The third group includes five papers on geo

Investigation of echo sounding parameters for the characterisation of bottom sediments in a sub-tropical reservoir

Directory of Open Access Journals (Sweden)

Stephan Hilgert

2016-07-01

Full Text Available The increasing number of reservoirs around the world today reaches a surface area of around 500,000 km², equaling one third of that of non-artificial surface water bodies. By impounding rivers through the construction of dams, riverine systems and biochemical cycles are disrupted. Different types of transported materials are trapped behind the dams and form layers of sediment. A method to characterise the spatially extensive sediment volumes with an EA 400 echo sounder was tested in the Vossoroca reservoir in the southeast of Brazil, Paraná State. A number of core and grab samples was taken and analysed for a variety of chemical and physical parameters. These data served as ground truthing for the hydro-acoustic assessment of the sediment. Eight hydro-acoustic parameters were derived from the echo signals using the Sonar5-Pro software. The major objective of defining the optimal survey parameters for the echo sounder as well as determining the difference between core and grab samples was reached by correlating the various single parameters and identifying the best combinations. Density and grain size distribution represented the best detectable sediment features with r-values of 0.94 and 0.95. The lower 38 kHz frequency generally had a better performance than the 200 kHz frequency. Results show that core samples reached a significantly higher quality of correlation for sediment characterisation. Additionally, it is was found that shorter pulse lengths yield a better characterisation. The results underline the potential of single beam echo sounders for extensive sediment characterisation. This methodology may be used for future mass balance estimations of large reservoirs.

Aural localization of silent objects by active human biosonar: neural representations of virtual echo-acoustic space.

Science.gov (United States)

Wallmeier, Ludwig; Kish, Daniel; Wiegrebe, Lutz; Flanagin, Virginia L

2015-03-01

Some blind humans have developed the remarkable ability to detect and localize objects through the auditory analysis of self-generated tongue clicks. These echolocation experts show a corresponding increase in 'visual' cortex activity when listening to echo-acoustic sounds. Echolocation in real-life settings involves multiple reflections as well as active sound production, neither of which has been systematically addressed. We developed a virtualization technique that allows participants to actively perform such biosonar tasks in virtual echo-acoustic space during magnetic resonance imaging (MRI). Tongue clicks, emitted in the MRI scanner, are picked up by a microphone, convolved in real time with the binaural impulse responses of a virtual space, and presented via headphones as virtual echoes. In this manner, we investigated the brain activity during active echo-acoustic localization tasks. Our data show that, in blind echolocation experts, activations in the calcarine cortex are dramatically enhanced when a single reflector is introduced into otherwise anechoic virtual space. A pattern-classification analysis revealed that, in the blind, calcarine cortex activation patterns could discriminate left-side from right-side reflectors. This was found in both blind experts, but the effect was significant for only one of them. In sighted controls, 'visual' cortex activations were insignificant, but activation patterns in the planum temporale were sufficient to discriminate left-side from right-side reflectors. Our data suggest that blind and echolocation-trained, sighted subjects may recruit different neural substrates for the same active-echolocation task. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

ECHO Gov Login | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Comparison of third-order plasma wave echoes with ballistic second-order plasma wave echoes

International Nuclear Information System (INIS)

Leppert, H.D.; Schuelter, H.; Wiesemann, K.

1982-01-01

The apparent dispersion of third-order plasma wave echoes observed in a high frequency plasma is compared with that of simultaneously observed ballistic second-order echoes. Amplitude and wavelength of third-order echoes are found to be always smaller than those of second-order echoes, however, the dispersion curves of both types of echoes are very similar. These observations are in qualitative agreement with calculations of special ballistic third-order echoes. The ballistic nature of the observed third-order echoes may, therefore, be concluded from these measurements. (author)

ECHO virus

Science.gov (United States)

... page: //medlineplus.gov/ency/article/001340.htm ECHO virus To use the sharing features on this page, please enable JavaScript. Enteric cytopathic human orphan (ECHO) viruses are a group of viruses that can lead ...

A full simulation of the Quetzal echo at the Mayan pyramid of Kukulkan at Chichen Itza in Mexico

Science.gov (United States)

Declercq, Nico F.; Degrieck, Joris; Briers, Rudy; Leroy, Oswald

2003-04-01

It is well known that a handclap in front of the staircase of the pyramid produces an echo that sounds similar to the chirp of the Quetzal bird. This phenomenon occurs due to diffraction. There exist some publications concerning this phenomenon and even some first attempts are reported to simulate it. However, no full simulation (amplitude, frequency, time) has ever been reported before. The present work presents a simulation which is based on the theory of the diffraction of plane waves and which takes into account continuity conditions. The latter theory is the building block for an extended theory that tackles the diffraction of a spherical sound pulse. By means of these principles it is possible to entirely simulate the echo following a handclap in front of the staircase. [Work supported by The Flemish Institute for the Encouragement of the Scientific and Technological Research in Industry (I.W.T.)

Fast spin-echo imaging

International Nuclear Information System (INIS)

Mackey, K.; Zoarski, G.; Bentson, J.R.; Lufkin, R.B.; Melki, P.; Jolesz, F.

1991-01-01

This paper reports on a partial radio-frequency (RF) echo-planar pulse sequence called contiguous slice fast spin echo (CSFSE) which is undergoing clinical trials for spine MR imaging. In this variation of rapid acquisition relaxation enhanced (RARE) spin-echo imaging, rapid 180 degrees RF pulse generated refocused echoes, producing T2-weighted images in about one-third the time of conventional double-echo technique. Forty patients with suspected pathology of the spine were imaged with conventional double-echo and closely matched CSFSE techniques on a GE Signa 1.5-T Advantage system. Cases were reviewed by two board-certified neuroradiologists. In all cases the CSFSE images were of equal or superior quality compared with those obtained with the conventional double-echo technique. Pathologic processes that were imaged consisted of inflammatory, neoplastic, posttraumatic, and degenerative conditions

Hearing abilities and sound reception of broadband sounds in an adult Risso's dolphin (Grampus griseus).

Science.gov (United States)

Mooney, T Aran; Yang, Wei-Cheng; Yu, Hsin-Yi; Ketten, Darlene R; Jen, I-Fan

2015-08-01

While odontocetes do not have an external pinna that guides sound to the middle ear, they are considered to receive sound through specialized regions of the head and lower jaw. Yet odontocetes differ in the shape of the lower jaw suggesting that hearing pathways may vary between species, potentially influencing hearing directionality and noise impacts. This work measured the audiogram and received sensitivity of a Risso's dolphin (Grampus griseus) in an effort to comparatively examine how this species receives sound. Jaw hearing thresholds were lowest (most sensitive) at two locations along the anterior, midline region of the lower jaw (the lower jaw tip and anterior part of the throat). Responses were similarly low along a more posterior region of the lower mandible, considered the area of best hearing in bottlenose dolphins. Left- and right-side differences were also noted suggesting possible left-right asymmetries in sound reception or differences in ear sensitivities. The results indicate best hearing pathways may vary between the Risso's dolphin and other odontocetes measured. This animal received sound well, supporting a proposed throat pathway. For Risso's dolphins in particular, good ventral hearing would support their acoustic ecology by facilitating echo-detection from their proposed downward oriented echolocation beam.

Monitoring of aquifer pump tests with Magnetic Resonance Sounding (MRS)

DEFF Research Database (Denmark)

Herckenrath, Daan; Auken, Esben; Bauer-Gottwein, Peter

2009-01-01

Magnetic Resonance Sounding (MRS) can provide valuable data to constrain and calibrate groundwater flow and transport models. With this non-invasive geophysical technique, field measurements of water content and hydraulic conductivities can be obtained. We developed a hydrogeophyiscal forward...

Grating stimulated echo

International Nuclear Information System (INIS)

Dubetsky, B.; Berman, P.R.; Sleator, T.

1992-01-01

A theory of a grating simulated echo (GTE) is developed. The GSE involves the sequential excitation of atoms by two counterpropagating traveling waves, a standing wave, and a third traveling wave. It is shown that the echo signal is very sensitive to small changes in atomic velocity, much more sensitive than the normal stimulated echo. Use of the GSE as a collisional probe or accelerometer is discussed

Speed of sound as a function of temperature for ultrasonic propagation in soybean oil

Science.gov (United States)

Oliveira, P. A.; Silva, R. M. B.; Morais, G. C.; Alvarenga, A. V.; Costa-Félix, R. P. B.

2016-07-01

Ultrasound has been used for characterization of liquid in several productive sectors and research. This work presents the studied about the behavior of the speed of sound in soybean oil with increasing temperature. The pulse echo technique allowed observing that the speed of sound decreases linearly with increasing temperature in the range 20 to 50 °C at 1 MHz. As result, a characteristic function capable to reproduce the speed of sound behavior in soybean oil, as a function of temperature was established, with the respective measurement uncertainty.

Objective function analysis for electric soundings (VES), transient electromagnetic soundings (TEM) and joint inversion VES/TEM

Science.gov (United States)

Bortolozo, Cassiano Antonio; Bokhonok, Oleg; Porsani, Jorge Luís; Monteiro dos Santos, Fernando Acácio; Diogo, Liliana Alcazar; Slob, Evert

2017-11-01

Ambiguities in geophysical inversion results are always present. How these ambiguities appear in most cases open to interpretation. It is interesting to investigate ambiguities with regard to the parameters of the models under study. Residual Function Dispersion Map (RFDM) can be used to differentiate between global ambiguities and local minima in the objective function. We apply RFDM to Vertical Electrical Sounding (VES) and TEM Sounding inversion results. Through topographic analysis of the objective function we evaluate the advantages and limitations of electrical sounding data compared with TEM sounding data, and the benefits of joint inversion in comparison with the individual methods. The RFDM analysis proved to be a very interesting tool for understanding the joint inversion method of VES/TEM. Also the advantage of the applicability of the RFDM analyses in real data is explored in this paper to demonstrate not only how the objective function of real data behaves but the applicability of the RFDM approach in real cases. With the analysis of the results, it is possible to understand how the joint inversion can reduce the ambiguity of the methods.

Rapid Gradient-Echo Imaging

Science.gov (United States)

Hargreaves, Brian

2012-01-01

Gradient echo sequences are widely used in magnetic resonance imaging (MRI) for numerous applications ranging from angiography to perfusion to functional MRI. Compared with spin-echo techniques, the very short repetition times of gradient-echo methods enable very rapid 2D and 3D imaging, but also lead to complicated “steady states.” Signal and contrast behavior can be described graphically and mathematically, and depends strongly on the type of spoiling: fully balanced (no spoiling), gradient spoiling, or RF-spoiling. These spoiling options trade off between high signal and pure T1 contrast while the flip angle also affects image contrast in all cases, both of which can be demonstrated theoretically and in image examples. As with spin-echo sequences, magnetization preparation can be added to gradient-echo sequences to alter image contrast. Gradient echo sequences are widely used for numerous applications such as 3D perfusion imaging, functional MRI, cardiac imaging and MR angiography. PMID:23097185

ECHO-UseFY17.png | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Help Content for ECHO Reports | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Analysis of the acoustic sound in MRI

Energy Technology Data Exchange (ETDEWEB)

Wada, Tetsuro; Hara, Akira; Kusakari, Jun; Yoshioka, Hiroshi; Niitsu, Mamoru; Itai, Yuji [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine; Ase, Yuji

1999-04-01

The noise level and power spectra of the acoustic sound exposed during the examination of Magnetic Resonance Imaging (MRI) using a MRI scanner (Philips Gyroscan 1.5 T) were measured at the position of the human auricle. The overall noise levels on T1-weighted images and T2-weighted images with Spin Echo were 105 dB and 98 dB, respectively. The overall noise level on T2-weighted images with Turbo Spin Echo was 110 dB. Fourier analysis revealed energy peaks ranging from 225 to 325 Hz and a steep high frequency cutoff for each pulse sequence. The MRI noise was not likely to cause permanent threshold shift. However, because of the inter-subject variation in susceptibility to acoustic trauma and to exclude the anxiety in patients, ear protectors were recommended for all patients during MRI testing. (author)

Analysis of Complex Marine Hazards on the Romanian Black Sea Shelf Using Combined Geophysical Methods

Science.gov (United States)

Samoila, I. V.; Radulescu, V.; Moise, G.; Diaconu, A.; Radulescu, R.

2017-12-01

Combined geophysical acquisition technologies including High Resolution 2D Seismic (HR2D), Multi-Beam Echo-Sounding (MBES), Sub-Bottom Profiling (SBP) and Magnetometry were used in the Western Black Sea (offshore Romania) to identify possible geohazards, such as gas escaping surface sediments and tectonic hazard areas up to 1 km below the seafloor. The National Project was funded by the Research and Innovation Ministry of Romania, and has taken place over 1.5 years with the purpose of creating risk maps for the surveyed pilot area. Using an array of geophysical methods and creating a workflow to identify geohazard susceptible areas on the Romanian Black Sea continental shelf is important and beneficial for future research projects. The SBP and MBES data show disturbed areas that can be interpreted as gas escapes on the surface of the seafloor, and some escapes were confirmed on the HR2D profiles. Shallow gas indicators like gas chimneys and acoustic blanking are usually delimited by vertical, sub-vertical and/or quasi-horizontal faults that mark possible hazard areas on shallow sedimentary sections. Interpreted seismic profiles show three main markers: one delimiting the Pliocene-Quaternary boundary and two for the Miocene (Upper and Lower). Vertical and quasi-horizontal faults are characteristic for the Upper Miocene, while the Lower Miocene has NW-SE horizontal faults. Faults and possible hazard areas were marked on seismic sections and were further correlated with the MBES, SBP, Magnetometry and previously recorded data, such as earthquake epicenters scattered offshore in the Western Black Sea. The main fault systems likely to cause those earthquakes also aid the migration of gas if the faults are not sealed. We observed that the gas escapes were correlated with faults described on the recent seismic profiles. Mapping hazard areas will have an important contribution to better understand the recent evolution of the Western Black Sea basin but also for projecting

Time-domain electromagnetic soundings collected in Dawson County, Nebraska, 2007-09

Science.gov (United States)

Payne, Jason; Teeple, Andrew

2011-01-01

Between April 2007 and November 2009, the U.S. Geological Survey, in cooperation with the Central Platte Natural Resources District, collected time-domain electro-magnetic (TDEM) soundings at 14 locations in Dawson County, Nebraska. The TDEM soundings provide information pertaining to the hydrogeology at each of 23 sites at the 14 locations; 30 TDEM surface geophysical soundings were collected at the 14 locations to develop smooth and layered-earth resistivity models of the subsurface at each site. The soundings yield estimates of subsurface electrical resistivity; variations in subsurface electrical resistivity can be correlated with hydrogeologic and stratigraphic units. Results from each sounding were used to calculate resistivity to depths of approximately 90-130 meters (depending on loop size) below the land surface. Geonics Protem 47 and 57 systems, as well as the Alpha Geoscience TerraTEM, were used to collect the TDEM soundings (voltage data from which resistivity is calculated). For each sounding, voltage data were averaged and evaluated statistically before inversion (inverse modeling). Inverse modeling is the process of creating an estimate of the true distribution of subsurface resistivity from the mea-sured apparent resistivity obtained from TDEM soundings. Smooth and layered-earth models were generated for each sounding. A smooth model is a vertical delineation of calculated apparent resistivity that represents a non-unique estimate of the true resistivity. Ridge regression (Interpex Limited, 1996) was used by the inversion software in a series of iterations to create a smooth model consisting of 24-30 layers for each sounding site. Layered-earth models were then generated based on results of smooth modeling. The layered-earth models are simplified (generally 1 to 6 layers) to represent geologic units with depth. Throughout the area, the layered-earth models range from 2 to 4 layers, depending on observed inflections in the raw data and smooth model

Rotary spin echoes

Energy Technology Data Exchange (ETDEWEB)

Solomon, I. [Commissariat a l' energie atomique et aux energies alternatives - CEA, Centre d' Etudes Nucleaires de Saclay, BP2, Gif-sur-Yvette (France)

1959-07-01

Torrey has observed the free precession of nuclear spins around an r-f field H{sub 1}, fixed in a frame rotating at the Larmor frequency ω{sub 0} = γH{sub 0} around a large d-c magnetic field H{sub 0}. He showed that for an H{sub 1}, much larger than inhomogeneity of H{sub 0}, the latter has a negligible effect on the decay of the spin magnetization which is mainly due to the inhomogeneity of H{sub 1}. We report here on a method of overcoming the inhomogeneity of H{sub 1}, by production of echoes in the rotating frame ('rotary echoes'). These echoes are obtained by a 180 deg. phase shift at t = τ on the r-f field so that H{sub 1}, is suddenly reversed, producing a re-focussing of the magnetization vectors at the time t = 2 τ. The rotary echoes so obtained are very similar to the usual spin-echoes with, however some specific features that make them particularly suitable for the measurement of long relaxation times. Reprint of a paper published in Physical Review Letters, vol. 2, no. 7, Apr 1959, p. 301-302.

Rotary spin echoes

International Nuclear Information System (INIS)

Solomon, I.

1959-01-01

Torrey has observed the free precession of nuclear spins around an r-f field H 1 , fixed in a frame rotating at the Larmor frequency ω 0 = γH 0 around a large d-c magnetic field H 0 . He showed that for an H 1 , much larger than inhomogeneity of H 0 , the latter has a negligible effect on the decay of the spin magnetization which is mainly due to the inhomogeneity of H 1 . We report here on a method of overcoming the inhomogeneity of H 1 , by production of echoes in the rotating frame ('rotary echoes'). These echoes are obtained by a 180 deg. phase shift at t = τ on the r-f field so that H 1 , is suddenly reversed, producing a re-focussing of the magnetization vectors at the time t = 2 τ. The rotary echoes so obtained are very similar to the usual spin-echoes with, however some specific features that make them particularly suitable for the measurement of long relaxation times. Reprint of a paper published in Physical Review Letters, vol. 2, no. 7, Apr 1959, p. 301-302

How can dolphins recognize fish according to their echoes? A statistical analysis of fish echoes.

Directory of Open Access Journals (Sweden)

Yossi Yovel

Full Text Available Echo-based object classification is a fundamental task of animals that use a biosonar system. Dolphins and porpoises should be able to rely on echoes to discriminate a predator from a prey or to select a desired prey from an undesired object. Many studies have shown that dolphins and porpoises can discriminate between objects according to their echoes. All of these studies however, used unnatural objects that can be easily characterized in human terminologies (e.g., metallic spheres, disks, cylinders. In this work, we collected real fish echoes from many angles of acquisition using a sonar system that mimics the emission properties of dolphins and porpoises. We then tested two alternative statistical approaches in classifying these echoes. Our results suggest that fish species can be classified according to echoes returning from porpoise- and dolphin-like signals. These results suggest how dolphins and porpoises can classify fish based on their echoes and provide some insight as to which features might enable the classification.

Efficient multichannel acoustic echo cancellation using constrained tap selection schemes in the subband domain

Science.gov (United States)

Desiraju, Naveen Kumar; Doclo, Simon; Wolff, Tobias

2017-12-01

Acoustic echo cancellation (AEC) is a key speech enhancement technology in speech communication and voice-enabled devices. AEC systems employ adaptive filters to estimate the acoustic echo paths between the loudspeakers and the microphone(s). In applications involving surround sound, the computational complexity of an AEC system may become demanding due to the multiple loudspeaker channels and the necessity of using long filters in reverberant environments. In order to reduce the computational complexity, the approach of partially updating the AEC filters is considered in this paper. In particular, we investigate tap selection schemes which exploit the sparsity present in the loudspeaker channels for partially updating subband AEC filters. The potential for exploiting signal sparsity across three dimensions, namely time, frequency, and channels, is analyzed. A thorough analysis of different state-of-the-art tap selection schemes is performed and insights about their limitations are gained. A novel tap selection scheme is proposed which overcomes these limitations by exploiting signal sparsity while not ignoring any filters for update in the different subbands and channels. Extensive simulation results using both artificial as well as real-world multichannel signals show that the proposed tap selection scheme outperforms state-of-the-art tap selection schemes in terms of echo cancellation performance. In addition, it yields almost identical echo cancellation performance as compared to updating all filter taps at a significantly reduced computational cost.

Wind yield forecast with Echo State Networks; Windertragsprognose mit Echo State Networks

Energy Technology Data Exchange (ETDEWEB)

Kobialka, Hans-Ulrich [Fraunhofer IAIS, Sankt Augustin (Germany)

2012-07-01

Statistical methods are able to create models of complex system dynamics which are difficult to capture analytically. This paper describes a wind energy prediction system based on a machine learning method, called Echo State Networks. Echo State Networks enable the training of large recurrent neural networks which are able to model and predict highly non-linear system dynamics. This paper gives a short description of Echo State Networks and the realization of the wind energy prediction system. (orig.)

Happy birthday Echo!

CERN Document Server

Staff Association

2010-01-01

You are reading the number hundred and one (no. 101) edition of our bulletin Echo. Just over four years ago, on 27th March 2006, the first untitled edition was published (Fig. 1 on the left). The title Echo appeared on the second edition on 10th April 2006 (Fig. 1 in the centre). Today (see Fig. 1 on the right), the layout is slightly different, but the structure of each edition has remained more or less the same: an editorial informing you of the important issues, followed by articles on club life, cultural activities (exhibitions and conferences), information from GAC-EPA, and special offers for our members.     Fig. 1 : Nos. 1, 2 and 100 of our twice-monthly publication Echo Echo was created in March 2006 when, much to our regret, CERN official communication and that of your representatives were separated. November 2009 saw a return to normal practice, and since then the CERN st...

A comparison of multi-echo spin-echo and triple-echo steady-state T2 mapping for in vivo evaluation of articular cartilage

International Nuclear Information System (INIS)

Juras, Vladimir; Szomolanyi, Pavol; Bohndorf, Klaus; Kronnerwetter, Claudia; Hager, Benedikt; Zbyn, Stefan; Heule, Rahel; Bieri, Oliver; Trattnig, Siegfried

2016-01-01

To assess the clinical relevance of T 2 relaxation times, measured by 3D triple-echo steady-state (3D-TESS), in knee articular cartilage compared to conventional multi-echo spin-echo T 2 -mapping. Thirteen volunteers and ten patients with focal cartilage lesions were included in this prospective study. All subjects underwent 3-Tesla MRI consisting of a multi-echo multi-slice spin-echo sequence (CPMG) as a reference method for T 2 mapping, and 3D TESS with the same geometry settings, but variable acquisition times: standard (TESSs 4:35min) and quick (TESSq 2:05min). T 2 values were compared in six different regions in the femoral and tibial cartilage using a Wilcoxon signed ranks test and the Pearson correlation coefficient (r). The local ethics committee approved this study, and all participants gave written informed consent. The mean quantitative T 2 values measured by CPMG (mean: 46±9ms) in volunteers were significantly higher compared to those measured with TESS (mean: 31±5ms) in all regions. Both methods performed similarly in patients, but CPMG provided a slightly higher difference between lesions and native cartilage (CPMG: 90ms→61ms [31%],p=0.0125;TESS 32ms→24ms [24%],p=0.0839). 3D-TESS provides results similar to those of a conventional multi-echo spin-echo sequence with many benefits, such as shortening of total acquisition time and insensitivity to B 1 and B 0 changes. (orig.)

A comparison of multi-echo spin-echo and triple-echo steady-state T2 mapping for in vivo evaluation of articular cartilage

Energy Technology Data Exchange (ETDEWEB)

Juras, Vladimir; Szomolanyi, Pavol [Medical University of Vienna, High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Vienna (Austria); Institute of Measurement Science, Department of Imaging Methods, Bratislava (Slovakia); Bohndorf, Klaus; Kronnerwetter, Claudia; Hager, Benedikt; Zbyn, Stefan [Medical University of Vienna, High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Vienna (Austria); Heule, Rahel; Bieri, Oliver [University of Basel Hospital, Division of Radiological Physics, Department of Radiology, Basel (Switzerland); Trattnig, Siegfried [Medical University of Vienna, High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Vienna (Austria); Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna (Austria); Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Austrian Cluster for Tissue Regeneration, Vienna (Austria)

2016-06-15

To assess the clinical relevance of T{sub 2} relaxation times, measured by 3D triple-echo steady-state (3D-TESS), in knee articular cartilage compared to conventional multi-echo spin-echo T{sub 2}-mapping. Thirteen volunteers and ten patients with focal cartilage lesions were included in this prospective study. All subjects underwent 3-Tesla MRI consisting of a multi-echo multi-slice spin-echo sequence (CPMG) as a reference method for T{sub 2} mapping, and 3D TESS with the same geometry settings, but variable acquisition times: standard (TESSs 4:35min) and quick (TESSq 2:05min). T{sub 2} values were compared in six different regions in the femoral and tibial cartilage using a Wilcoxon signed ranks test and the Pearson correlation coefficient (r). The local ethics committee approved this study, and all participants gave written informed consent. The mean quantitative T{sub 2} values measured by CPMG (mean: 46±9ms) in volunteers were significantly higher compared to those measured with TESS (mean: 31±5ms) in all regions. Both methods performed similarly in patients, but CPMG provided a slightly higher difference between lesions and native cartilage (CPMG: 90ms→61ms [31%],p=0.0125;TESS 32ms→24ms [24%],p=0.0839). 3D-TESS provides results similar to those of a conventional multi-echo spin-echo sequence with many benefits, such as shortening of total acquisition time and insensitivity to B{sub 1} and B{sub 0} changes. (orig.)

Measurement of sound velocity profiles in fluids for process monitoring

International Nuclear Information System (INIS)

Wolf, M; Kühnicke, E; Lenz, M; Bock, M

2012-01-01

In ultrasonic measurements, the time of flight to the object interface is often the only information that is analysed. Conventionally it is only possible to determine distances or sound velocities if the other value is known. The current paper deals with a novel method to measure the sound propagation path length and the sound velocity in media with moving scattering particles simultaneously. Since the focal position also depends on sound velocity, it can be used as a second parameter. Via calibration curves it is possible to determine the focal position and sound velocity from the measured time of flight to the focus, which is correlated to the maximum of averaged echo signal amplitude. To move focal position along the acoustic axis, an annular array is used. This allows measuring sound velocity locally resolved without any previous knowledge of the acoustic media and without a reference reflector. In previous publications the functional efficiency of this method was shown for media with constant velocities. In this work the accuracy of these measurements is improved. Furthermore first measurements and simulations are introduced for non-homogeneous media. Therefore an experimental set-up was created to generate a linear temperature gradient, which also causes a gradient of sound velocity.

The thermal and dynamical state of the atmosphere during polar mesosphere winter echoes

Directory of Open Access Journals (Sweden)

F.-J. Lübken

2006-01-01

Full Text Available In January 2005, a total of 18 rockets were launched from the Andøya Rocket Range in Northern Norway (69° N into strong VHF radar echoes called 'Polar Mesosphere Winter Echoes' (PMWE. The echoes were observed in the lower and middle mesosphere during large solar proton fluxes. In general, PMWE occur much more seldom compared to their summer counterparts PMSE (typical occurrence rates at 69° N are 1–3% vs. 80%, respectively. Our in-situ measurements by falling sphere, chaff, and instrumented payloads provide detailed information about the thermal and dynamical state of the atmosphere and therefore allow an unprecedented study of the background atmosphere during PMWE. There are a number of independent observations indicating that neutral air turbulence has caused PMWE. Ion density fluctuations show a turbulence spectrum within PMWE and no fluctuations outside. Temperature lapse rates close to the adiabatic gradient are observed in the vicinity of PMWE indicating persistent turbulent mixing. The spectral broadening of radar echoes is consistent with turbulent velocity fluctuations. Turbulence also explains the mean occurrence height of PMWE (~68–75 km: viscosity increases rapidly with altitude and destroys any small scale fluctuations in the upper mesosphere, whereas electron densities are usually too low in the lower mesosphere to cause significant backscatter. The seasonal variation of echoes in the lower mesosphere is in agreement with a turbulence climatology derived from earlier sounding rocket flights. We have performed model calculations to study the radar backscatter from plasma fluctuations caused by neutral air turbulence. We find that volume reflectivities observed during PMWE are in quantitative agreement with theory. Apart from turbulence the most crucial requirement for PMWE is a sufficiently large number of electrons, for example produced by solar proton events. We have studied the sensitivity of the radar echo strength on

Interface for Barge-in Free Spoken Dialogue System Based on Sound Field Reproduction and Microphone Array

Directory of Open Access Journals (Sweden)

Hinamoto Yoichi

2007-01-01

Full Text Available A barge-in free spoken dialogue interface using sound field control and microphone array is proposed. In the conventional spoken dialogue system using an acoustic echo canceller, it is indispensable to estimate a room transfer function, especially when the transfer function is changed by various interferences. However, the estimation is difficult when the user and the system speak simultaneously. To resolve the problem, we propose a sound field control technique to prevent the response sound from being observed. Combined with a microphone array, the proposed method can achieve high elimination performance with no adaptive process. The efficacy of the proposed interface is ascertained in the experiments on the basis of sound elimination and speech recognition.

An apparatus for the determination of speeds of sound in fluids

International Nuclear Information System (INIS)

Gedanitz, Holger; Davila, Maria J.; Baumhoegger, Elmar; Span, Roland

2010-01-01

An apparatus for accurate measurements of the sound velocity in fluids is described, which is based on the pulse-echo technique, and operates up to 30 MPa in the temperature range between (250 and 350) K. The expanded uncertainties (k = 2) in the speed of sound measurements are 0.006%, 6 mK in the temperature, 2.1 hPa in the pressure up to 3 MPa, and 23.9 hPa above this value. Measurements of the speed of sound for nitrogen from (250 to 350) K and for water at temperatures between (303.15 and 323.15) K are presented at pressures up to 30 MPa to validate the new apparatus. The expanded overall uncertainty of the measurements on nitrogen and water were estimated to be 0.011% and 0.006%, respectively. The speed of sound of both fluids was compared with literature sources showing an excellent agreement among them, with relative deviations lower than 0.01% in nitrogen and 0.006% in water.

Bi-Static Deep Electromagnetic Soundings for Martian Subsurface Characterization: Experimental Validation in the Egyptian Western Desert

Science.gov (United States)

Ciarletti, V.; Le Gall, A.; Berthelier, J. J.; Corbel, Ch.; Dolon, F.; Ney, R.; Reineix, A.; Guiffaud, Ch.; Clifford, S.; Heggy, E.

2007-03-01

A bi-static version of the HF GPR TAPIR developed for martian deep soundings has been operated in the Egyptian Western Desert. The study presented focuses on the retrieval of the direction of arrival of the observed echoes on both simulated and measured d

Classification of radar echoes using fractal geometry

International Nuclear Information System (INIS)

Azzaz, Nafissa; Haddad, Boualem

2017-01-01

Highlights: • Implementation of two concepts of fractal geometry to classify two types of meteorological radar echoes. • A new approach, called a multi-scale fractal dimension is used for classification between fixed echoes and rain echoes. • An Automatic identification system of meteorological radar echoes was proposed using fractal geometry. - Abstract: This paper deals with the discrimination between the precipitation echoes and the ground echoes in meteorological radar images using fractal geometry. This study aims to improve the measurement of precipitations by weather radars. For this, we considered three radar sites: Bordeaux (France), Dakar (Senegal) and Me lbourne (USA). We showed that the fractal dimension based on contourlet and the fractal lacunarity are pertinent to discriminate between ground and precipitation echoes. We also demonstrated that the ground echoes have a multifractal structure but the precipitations are more homogeneous than ground echoes whatever the prevailing climate. Thereby, we developed an automatic classification system of radar using a graphic interface. This interface, based on the fractal geometry makes possible the identification of radar echoes type in real time. This system can be inserted in weather radar for the improvement of precipitation estimations.

Geophysical Investigation of a Thermokarst Lake Talik in Continuous Permafrost

Science.gov (United States)

Creighton, A.; Parsekian, A.; Arp, C. D.; Jones, B. M.; Babcock, E.; Bondurant, A. C.

2016-12-01

On the Arctic Coastal Plain (ACP) of northern Alaska, shallow thermokarst lakes cover up to 25% of the landscape. These lakes occupy depressions created by the subsidence of thawed, ice-rich permafrost. Areas of unfrozen sediment, or taliks, can form under lakes that have a mean annual bottom temperature greater than 0°C. The geometry of these taliks, as well as the processes that create them, are important for understanding interactions between surface water, groundwater, and carbon cycling. Non-invasive geophysical methods are a useful means to study talik sediments as borehole studies yield few data points, and the contrast between unfrozen and frozen sediments is an ideal geophysical target. To study talik configuration associated with an actively expanding thermokarst lake, we conducted a geophysical transect across Peatball Lake. This lake has an estimated initiation age of 1400 calendar years BP. Over the past 60 years, lake surface area has increased through thermal and mechanical shoreline erosion. A talik of previously unknown thickness likely exists below Peatball Lake. We conducted a transect of transient electromagnetic soundings across the lake extending into the surrounding terrestrial environment. Since permafrost has relatively high resistivity compared to talik sediments, the interpreted electrical structure of the subsurface likely reflects talik geometry. We also conducted nuclear magnetic resonance soundings at representative locations along the transect. These measurements can provide data on sub-lake sediment properties including water content. Together, these measurements resolve the talik structure across the lake transect and showed evidence of varying talik thicknesses from the lake edge to center. These is no evidence of a talik at the terrestrial control sites. These results can help constrain talik development models and thus provide insight into Arctic and permafrost processes in the face of a changing climate.

A comparison of multi-echo spin-echo and triple-echo steady-state T2 mapping for in vivo evaluation of articular cartilage.

Science.gov (United States)

Juras, Vladimir; Bohndorf, Klaus; Heule, Rahel; Kronnerwetter, Claudia; Szomolanyi, Pavol; Hager, Benedikt; Bieri, Oliver; Zbyn, Stefan; Trattnig, Siegfried

2016-06-01

To assess the clinical relevance of T2 relaxation times, measured by 3D triple-echo steady-state (3D-TESS), in knee articular cartilage compared to conventional multi-echo spin-echo T2-mapping. Thirteen volunteers and ten patients with focal cartilage lesions were included in this prospective study. All subjects underwent 3-Tesla MRI consisting of a multi-echo multi-slice spin-echo sequence (CPMG) as a reference method for T2 mapping, and 3D TESS with the same geometry settings, but variable acquisition times: standard (TESSs 4:35min) and quick (TESSq 2:05min). T2 values were compared in six different regions in the femoral and tibial cartilage using a Wilcoxon signed ranks test and the Pearson correlation coefficient (r). The local ethics committee approved this study, and all participants gave written informed consent. The mean quantitative T2 values measured by CPMG (mean: 46±9ms) in volunteers were significantly higher compared to those measured with TESS (mean: 31±5ms) in all regions. Both methods performed similarly in patients, but CPMG provided a slightly higher difference between lesions and native cartilage (CPMG: 90ms→61ms [31%],p=0.0125;TESS 32ms→24ms [24%],p=0.0839). 3D-TESS provides results similar to those of a conventional multi-echo spin-echo sequence with many benefits, such as shortening of total acquisition time and insensitivity to B1 and B0 changes. • 3D-TESS T 2 mapping provides clinically comparable results to CPMG in shorter scan-time. • Clinical and investigational studies may benefit from high temporal resolution of 3D-TESS. • 3D-TESS T 2 values are able to differentiate between healthy and damaged cartilage.

Short echo time, fast gradient-echo imaging

International Nuclear Information System (INIS)

Haacke, E.M.; Lenz, G.W.

1987-01-01

Present fast-gradient-echoes schemes can acquire volume data rapidly and are flexible in T1 or T1/T2 contrast behavior. However, sequences used to date employ echo time (TE) values of about 15 ms +- 5 and, because of in vivo field inhomogeneities (short T2), they suffer badly from signal loss near sinuses and tissue boundaries. The authors implemented sequences with TE = 4-6 ms and found significant improvement in image quality, especially at high fields. Examples with long TEs vs. short TEs are given in the knee, spine, head, and orbits. Further advantages include (1) faster repetition times (15 ms), (2) higher-quality spin-density or T1-weighted images, and (3) reduction of blood motion artifacts

Depth study of insular shelf electric sounding in the Las Mercedes anomaly (Tacuarembo)

International Nuclear Information System (INIS)

Cicalese, H.

1983-01-01

In the framework of Uranium prospecting Programme the geophysics team composed by BRGM and DINAMIGE workers were carried out an study about insular shelf electric sounding on the Mercedes area.They were studied the following topics: geographical location, geologic framework, methods, materials and some results

Longitudinal collective echoes in coasting particle beams

Directory of Open Access Journals (Sweden)

Ahmed Al-Khateeb

2003-01-01

Full Text Available Longitudinal ballistic and collective beam echoes with diffusion effects are investigated theoretically. In the presence of the space-charge impedance, the collective echo amplitude is obtained as a closed form expression. In contrast to the ballistic case, the collective echo amplitude consists of one maximum at time t_{echo}. The echo amplitude grows up and damps down with a rate proportional to the Landau damping rate of space-charge waves. The effect of weak diffusion is found to modify the ballistic and the collective echo amplitudes in the same manner. This effect of diffusion was confirmed using a “noiseless,” grid-based simulation code. As a first application the amount of numerical diffusion in our simulation code was determined using the echo effect.

Sound velocity variation as function of polarization state in Lead Zirconate Titanate (PZT) Ceramics

International Nuclear Information System (INIS)

Essolaani, W; Farhat, N

2012-01-01

There are several ultrasonic techniques to measure the sound velocity, for example, the pulse-echo method. In such method, the size of transducer used to measure the sound velocity must be in the same order of the sample size. If not, the incompatibility of sizes becomes an error source of the sound velocity measurement. In this work, the Laser Induced Pressure Pulse (LIPP) method is used as ultrasonic method. This method has been very useful for studying the spatial distribution of charges and polarization in dielectrics. We take advantage of the fact that the method allows the sound velocity measurement, to study its variation as function of polarization state in (PZT) ceramics. In a sample with a known thickness e, the sound velocity ν is deduced from the measurement of the transit time T. The sound velocity depends on the elastic constants which in turn they depend on poling conditions. Thus, the variation of the sound velocity is related to the direction and the amplitude of the polarization.

A multi-scale permafrost investigation along the Alaska Highway Corridor based on airborne electromagnetic and auxiliary geophysical data

Science.gov (United States)

Minsley, B. J.; Kass, M. A.; Bloss, B.; Pastick, N.; Panda, S. K.; Smith, B. D.; Abraham, J. D.; Burns, L. E.

2012-12-01

More than 8000 square kilometers of airborne electromagnetic (AEM) data were acquired along the Alaska Highway Corridor in 2005-2006 by the Alaska Department of Natural Resources Division of Geological and Geophysical Surveys. Because this large AEM dataset covers diverse geologic and permafrost settings, it is an excellent testbed for studying the electrical geophysical response from a wide range of subsurface conditions. These data have been used in several recent investigations of geology, permafrost, and infrastructure along the highway corridor. In this study, we build on existing interpretations of permafrost features by re-inverting the AEM data using traditional least squares inversion techniques as well as recently developed stochastic methods aimed at quantifying uncertainty in geophysical data. Ground-based geophysical measurements, including time-domain electromagnetic soundings, surface nuclear magnetic resonance soundings, and shallow frequency-domain electromagnetic profiles, have also been acquired to help validate and extend the AEM interpretations. Here, we focus on the integration of different types of data to yield an improved characterization of permafrost, including: methods to discriminate between geologic and thermal controls on resistivity; identifying relationships between shallow resistivity and active layer thickness by incorporating auxiliary remote sensing data and ground-based measurements; quantifying apparent slope-aspect-resistivity relationships, where south-facing slopes appear less resistive than north-facing slopes within similar geologic settings; and investigating an observed decrease in resistivity beneath several areas associated with recent fires.

Understanding Animal Detection of Precursor Earthquake Sounds.

Science.gov (United States)

Garstang, Michael; Kelley, Michael C

2017-08-31

We use recent research to provide an explanation of how animals might detect earthquakes before they occur. While the intrinsic value of such warnings is immense, we show that the complexity of the process may result in inconsistent responses of animals to the possible precursor signal. Using the results of our research, we describe a logical but complex sequence of geophysical events triggered by precursor earthquake crustal movements that ultimately result in a sound signal detectable by animals. The sound heard by animals occurs only when metal or other surfaces (glass) respond to vibrations produced by electric currents induced by distortions of the earth's electric fields caused by the crustal movements. A combination of existing measurement systems combined with more careful monitoring of animal response could nevertheless be of value, particularly in remote locations.

Theory of single-photon echo (SP-echo) and the possibility of its experimental study in the gamma-region

International Nuclear Information System (INIS)

Moiseev, S.A.

1997-01-01

The single-photon echo (SP-echo) effect is predicted to appear in the case of three-level medium excitation by means of a single photon propagating to the medium along two optical paths with a mutual time delay surpassing the temporal duration of the photon wave packet. The quantum electrodynamical theory describing this interaction is presented and the S-matrix of the field is shown for infinite time (t=∞). Using the S-matrix approach, physical properties of the scattering field are studied. Hence, it is shown that the field has an echo signal at the ω 32 0 carrier frequency. It has been shown that the echo signal exists only in the field amplitude while being absent in its intensity behaviour. Thus, SP-echo is an interference effect and is not influenced by the energy irradiation. The problems of SP-echo detection in the gamma-region (where special generation difficulties appear) are discussed. The influence of the additional detection of theω 21 0 frequency field on the echo signal has been shown. A special case is the EPR-paradox which can appear within the echo phenomenon

Theory of single-photon echo (SP-echo) and the possibility of its experimental study in the gamma-region

Energy Technology Data Exchange (ETDEWEB)

Moiseev, S.A

1997-05-15

The single-photon echo (SP-echo) effect is predicted to appear in the case of three-level medium excitation by means of a single photon propagating to the medium along two optical paths with a mutual time delay surpassing the temporal duration of the photon wave packet. The quantum electrodynamical theory describing this interaction is presented and the S-matrix of the field is shown for infinite time (t={infinity}). Using the S-matrix approach, physical properties of the scattering field are studied. Hence, it is shown that the field has an echo signal at the {omega}{sub 32}{sup 0} carrier frequency. It has been shown that the echo signal exists only in the field amplitude while being absent in its intensity behaviour. Thus, SP-echo is an interference effect and is not influenced by the energy irradiation. The problems of SP-echo detection in the gamma-region (where special generation difficulties appear) are discussed. The influence of the additional detection of the{omega}{sub 21}{sup 0} frequency field on the echo signal has been shown. A special case is the EPR-paradox which can appear within the echo phenomenon.

A radar-echo model for Mars

International Nuclear Information System (INIS)

Thompson, T.W.; Moore, H.J.

1990-01-01

Researchers developed a radar-echo model for Mars based on 12.6 cm continuous wave radio transmissions backscattered from the planet. The model broadly matches the variations in depolarized and polarized total radar cross sections with longitude observed by Goldstone in 1986 along 7 degrees S. and yields echo spectra that are generally similiar to the observed spectra. Radar map units in the model include an extensive cratered uplands unit with weak depolarized echo cross sections, average thermal inertias, moderate normal refelectivities, and moderate rms slopes; the volcanic units of Tharsis, Elysium, and Amazonis regions with strong depolarized echo cross sections, low thermal inertia, low normal reflectivities, and large rms slopes; and the northern planes units with moderate to strong depolarized echo cross sections, moderate to very high thermal inertias, moderate to large normal reflectivities, and moderate rms slopes. The relevance of the model to the interpretation of radar echoes from Mars is discussed

The acoustics of the echo cornet

Science.gov (United States)

Pyle, Robert W., Jr.; Klaus, Sabine K.

2002-11-01

The echo cornet was an instrument produced by a number of makers in several countries from about the middle of the nineteenth to the early twentieth centuries. It consists of an ordinary three-valve cornet to which a fourth valve has been added, downstream of the three normal valves. The extra valve diverts the airstream from the normal bell to an ''echo'' bell that gives a muted tone quality. Although the air column through the echo bell is typically 15 cm longer than the path through the normal bell, there is no appreciable change of playing pitch when the echo bell is in use. Acoustic input impedance and impulse response measurements and consideration of the standing-wave pattern within the echo bell show how this can be so. Acoustically, the echo bell is more closely related to hand-stopping on the French horn than to the mutes commonly used on the trumpet and cornet.

A Two-Level Sound Classification Platform for Environmental Monitoring

Directory of Open Access Journals (Sweden)

Stelios A. Mitilineos

2018-01-01

Full Text Available STORM is an ongoing European research project that aims at developing an integrated platform for monitoring, protecting, and managing cultural heritage sites through technical and organizational innovation. Part of the scheduled preventive actions for the protection of cultural heritage is the development of wireless acoustic sensor networks (WASNs that will be used for assessing the impact of human-generated activities as well as for monitoring potentially hazardous environmental phenomena. Collected sound samples will be forwarded to a central server where they will be automatically classified in a hierarchical manner; anthropogenic and environmental activity will be monitored, and stakeholders will be alarmed in the case of potential malevolent behavior or natural phenomena like excess rainfall, fire, gale, high tides, and waves. Herein, we present an integrated platform that includes sound sample denoising using wavelets, feature extraction from sound samples, Gaussian mixture modeling of these features, and a powerful two-layer neural network for automatic classification. We contribute to previous work by extending the proposed classification platform to perform low-level classification too, i.e., classify sounds to further subclasses that include airplane, car, and pistol sounds for the anthropogenic sound class; bird, dog, and snake sounds for the biophysical sound class; and fire, waterfall, and gale for the geophysical sound class. Classification results exhibit outstanding classification accuracy in both high-level and low-level classification thus demonstrating the feasibility of the proposed approach.

78 FR 33369 - Takes of Marine Mammals Incidental to Specified Activities; Low-Energy Marine Geophysical Survey...

Science.gov (United States)

2013-06-04

... information on the study, their modeling process of the experiment in shallow, intermediate, and deep water... element operation and that it uses shallow-water sound propagation as a proxy for deep water propagation... geophysical (i.e., seismic) survey in the deep water of the Gulf of Mexico, April to May 2013. DATES...

The Geysers-Clear Lake geothermal area, California - an updated geophysical perspective of heat sources

Science.gov (United States)

Stanley, W.D.; Blakely, R.J.

1995-01-01

The Geysers-Clear Lake geothermal area encompasses a large dry-steam production area in The Geysers field and a documented high-temperature, high-pressure, water-dominated system in the area largely south of Clear Lake, which has not been developed. An updated view is presented of the geological/geophysical complexities of the crust in this region in order to address key unanswered questions about the heat source and tectonics. Forward modeling, multidimensional inversions, and ideal body analysis of the gravity data, new electromagnetic sounding models, and arguments made from other geophysical data sets suggest that many of the geophysical anomalies have significant contributions from rock property and physical state variations in the upper 7 km and not from "magma' at greater depths. Regional tectonic and magmatic processes are analyzed to develop an updated scenario for pluton emplacement that differs substantially from earlier interpretations. In addition, a rationale is outlined for future exploration for geothermal resources in The Geysers-Clear Lake area. -from Authors

Experimental separation of a frequency spin echo signal

International Nuclear Information System (INIS)

Bun'kov, Yu.M.; Dmitriev, V.V.

1981-01-01

To study systems with bound nuclear-electron precession CsMnF 2 antiferromagnetic light-plane monocrystal was investigated. Crystal orientation was carried out by roentgenoscopy. Measurements were performed at helium temperatures in the 500-700 MHz frequency range. A NMR pulsed spectrometer with generators of both resonance and doubled frequency was used to produce an echo signal (to study by the parametric echo method). It was shown that the theory of the formation of a frequency modulated echo (FM echo) did not fully describe the properties of the echo signals in systems with dynamic frequency shift (DFS). An intense spin echo signal, which formation was apparently connected with other nonlinear properties of the systems with nuclear-electron precession, was observed. The spin echo signal in magnetics with DFS, which properties correspond to notions of the frequency mechanism of echo formation, was experimentally separated. As a result of the investigations it had been possible to settle contradictions between the theory of FM echo formation and the experimental results for the last 9 years. It turned out that the mechanism of FM echo formation in the magnetics with bound nuclear-electron precession was effective only at large delay times between the pulses. In the range of small delays the FM echo is ''jammed'' by a gigantic echo signal of a nature different from that of the traditional FM signal. The constant of gigantic echo intensity drop at increasing delay between the pulses weakly depends on spin-spin relaxation time [ru

Single-shot echo-planar imaging of multiple sclerosis: effects of varying echo time

International Nuclear Information System (INIS)

Wolansky, L.J.; Chong, S.; Liu, W.C.; Kang, E.; Simpson, S.W.; Karimi, S.; Akbari, H.

1999-01-01

Our aim was to determine the relative merits of short and long echo times (TE) with single-shot echo-planar imaging for imaging cerebral lesions such as multiple sclerosis. We examined seven patients with clinically definite multiple sclerosis were imaged at 1.5 T. Patients were scanned with spin-echo, single-shot echo-planar imaging, using TEs of 45, 75, 105, and 135 ms. Region of interest (ROI) measurements were performed on 36 lesions at or above the level of the corona radiata. The mean image contrast (IC) was highest (231.1) for a TE of 45 ms, followed by 75 ms (218.9), 105 ms (217.9), and 135 ms (191.6). When mean contrast-to-noise ratios (C/N) were compared, the value was again highest (29.7) for TE 45 ms, followed by 75 ms (28.9), 105 ms (28.5), and 135 ms (26.3). In a lesion-by-lesion comparison, TE 45 ms had the highest IC and C/N in the largest number of cases (50 % and 47.2 %, respectively). IC and C/N for TE 45 ms were superior to those of 75 ms in 64 % and 58 %, respectively. These results support the use of relatively short TEs for single-shot echo-planar imaging in the setting of cerebral lesions such as multiple sclerosis. (orig.) (orig.)

Wavelet-LMS algorithm-based echo cancellers

Science.gov (United States)

Seetharaman, Lalith K.; Rao, Sathyanarayana S.

2002-12-01

This paper presents Echo Cancellers based on the Wavelet-LMS Algorithm. The performance of the Least Mean Square Algorithm in Wavelet transform domain is observed and its application in Echo cancellation is analyzed. The Widrow-Hoff Least Mean Square Algorithm is most widely used algorithm for Adaptive filters that function as Echo Cancellers. The present day communication signals are widely non-stationary in nature and some errors crop up when Least Mean Square Algorithm is used for the Echo Cancellers handling such signals. The analysis of non-stationary signals often involves a compromise between how well transitions or discontinuities can be located. The multi-scale or multi-resolution of signal analysis, which is the essence of wavelet transform, makes Wavelets popular in non-stationary signal analysis. In this paper, we present a Wavelet-LMS algorithm wherein the wavelet coefficients of a signal are modified adaptively using the Least Mean Square Algorithm and then reconstructed to give an Echo-free signal. The Echo Canceller based on this Algorithm is found to have a better convergence and a comparatively lesser MSE (Mean Square error).

A neurally inspired musical instrument classification system based upon the sound onset.

Science.gov (United States)

Newton, Michael J; Smith, Leslie S

2012-06-01

Physiological evidence suggests that sound onset detection in the auditory system may be performed by specialized neurons as early as the cochlear nucleus. Psychoacoustic evidence shows that the sound onset can be important for the recognition of musical sounds. Here the sound onset is used in isolation to form tone descriptors for a musical instrument classification task. The task involves 2085 isolated musical tones from the McGill dataset across five instrument categories. A neurally inspired tone descriptor is created using a model of the auditory system's response to sound onset. A gammatone filterbank and spiking onset detectors, built from dynamic synapses and leaky integrate-and-fire neurons, create parallel spike trains that emphasize the sound onset. These are coded as a descriptor called the onset fingerprint. Classification uses a time-domain neural network, the echo state network. Reference strategies, based upon mel-frequency cepstral coefficients, evaluated either over the whole tone or only during the sound onset, provide context to the method. Classification success rates for the neurally-inspired method are around 75%. The cepstral methods perform between 73% and 76%. Further testing with tones from the Iowa MIS collection shows that the neurally inspired method is considerably more robust when tested with data from an unrelated dataset.

Assessment of diagnosing metastatic bone tumor on T2*-weighted images. Comparison between turbo spin echo (TSE) method and gradient echo (GE) method

International Nuclear Information System (INIS)

Hayashi, Takahiko; Sugiyama, Akira; Katayama, Motoyuki

1996-01-01

We examined the usefulness of T2 * weighted gradient field echo images for diagnosis for metastatic bone tumors in comparison with T2 weighted turbo spin echo (fast spin echo) images. In T2 * weighted gradient field echo sequence to obtain maximum contrast-to-noise ratio (CNR), we experimentally manipulated flip angle (FA) (5deg-90deg), repetition time (TR) (400, 700 msec), and echo time (TE) (10-50 msec). The best CNR was 16.4 in fast low angle shot (FLASH) (TE: 24 msec, TR: 700 msec, FA: 40deg). Magnetic resonance imaging was carried out in 28 patients with metastatic bone tumors. In addition to conventional T1 weighted spin echo images, T2 weighted turbo spin echo (fast spin echo images) and T2 * weighted gradient field echo images were obtained. T2 * weighted gradient field echo images were superior to T2 weighted turbo spin echo (fast spin echo) images in delineating the tumors, adjacent fat tissues, and bone marrow. (author)

Implementing statistical analysis in multi-channel acoustic impact-echo testing of concrete bridge decks: Determining thresholds for delamination detection

Science.gov (United States)

Hendricks, Lorin; Spencer Guthrie, W.; Mazzeo, Brian

2018-04-01

An automated acoustic impact-echo testing device with seven channels has been developed for faster surveying of bridge decks. Due to potential variations in bridge deck overlay thickness, varying conditions between testing passes, and occasional imprecise equipment calibrations, a method that can account for variations in deck properties and testing conditions was necessary to correctly interpret the acoustic data. A new methodology involving statistical analyses was therefore developed. After acoustic impact-echo data are collected and analyzed, the results are normalized by the median for each channel, a Gaussian distribution is fit to the histogram of the data, and the Kullback-Leibler divergence test or Otsu's method is then used to determine the optimum threshold for differentiating between intact and delaminated concrete. The new methodology was successfully applied to individual channels of previously unusable acoustic impact-echo data obtained from a three-lane interstate bridge deck surfaced with a polymer overlay, and the resulting delamination map compared very favorably with the results of a manual deck sounding survey.

Sound-scattering layers of the Black Sea based on ADCP observations

Science.gov (United States)

Morozov, A. N.; Lemeshko, E. M.; Fedorov, S. V.

2017-09-01

The paper discusses the results of expeditions to the northwestern part of the Black Sea carried out in 2004-2008. Acoustic Doppler Current Profilers (ADCP) with an operating frequency of 150 and 300 kHz were used as the echo sounders. The characteristic scales of the spatial variability of sound scattering in the Black Sea were determined; the revealed peculiarities are interpreted. The characteristics of a deep soundscattering layer in the Black Sea are given.

SAGE (Summer of Applied Geophysical Experience): Learning Geophysics by Doing Geophysics

Science.gov (United States)

Jiracek, G. R.; Baldridge, W. S.; Biehler, S.; Braile, L. W.; Ferguson, J. F.; Gilpin, B. E.; Pellerin, L.

2005-12-01

SAGE, a field-based educational program in applied geophysical methods has been an REU site for 16 years and completed its 23rd year of operation in July 2005. SAGE teaches the major geophysical exploration methods (including seismics, gravity, magnetics, and electromagnetics) and applies them to the solution of specific local and regional geologic problems. These include delineating buried hazardous material; mapping archaeological sites; and studying the structure, tectonics, and water resources of the Rio Grande rift in New Mexico. Nearly 600 graduates, undergraduates, and professionals have attended SAGE since 1983. Since 1990 REU students have numbered 219 coming from dozens of different campuses. There have been 124 underrepresented REU students including 100 women, 14 Hispanics, 7 Native Americans, and 3 African Americans. Tracking of former REU students has revealed that 81% have gone on to graduate school. Keys to the success of SAGE are hands-on immersion in geophysics for one month and a partnership between academia, industry, and a federal laboratory. Successful approaches at SAGE include: 1) application of the latest equipment by all students; 2) continued updating of equipment, computers, and software by organizing universities and industry affiliates; 3) close ties with industry who provide supplemental instruction, furnish new equipment and software, and alert students to the current industry trends and job opportunities; 4) two-team, student data analysis structure that simultaneously addresses specific geophysical techniques and their integration; and 5) oral and written reports patterned after professional meetings and journals. An eight member, 'blue ribbon' advisory panel from academia, industry, and the federal government has been set up to maintain the vitality of SAGE by addressing such issues as funding, new faculty, organization, and vision. SAGE is open to students from any university (or organization) with backgrounds including

Learning about hydrothermal volcanic activity by modeling induced geophysical changes

Science.gov (United States)

Currenti, Gilda M.; Napoli, Rosalba

2017-05-01

Motivated by ongoing efforts to understand the nature and the energy potential of geothermal resources, we devise a coupled numerical model (hydrological, thermal, mechanical), which may help in the characterization and monitoring of hydrothermal systems through computational experiments. Hydrothermal areas in volcanic regions arise from a unique combination of geological and hydrological features which regulate the movement of fluids in the vicinity of magmatic sources capable of generating large quantities of steam and hot water. Numerical simulations help in understanding and characterizing rock-fluid interaction processes and the geophysical observations associated with them. Our aim is the quantification of the response of different geophysical observables (i.e. deformation, gravity and magnetic field) to hydrothermal activity on the basis of a sound geological framework (e.g. distribution and pathways of the flows, the presence of fractured zones, caprock). A detailed comprehension and quantification of the evolution and dynamics of the geothermal systems and the definition of their internal state through a geophysical modeling approach are essential to identify the key parameters for which the geothermal system may fulfill the requirements to be exploited as a source of energy. For the sake of illustration only, the numerical computations are focused on a conceptual model of the hydrothermal system of Vulcano Island by simulating a generic 1-year unrest and estimating different geophysical changes. We solved (i) the mass and energy balance equations of flow in porous media for temperature, pressure and density changes, (ii) the elastostatic equation for the deformation field and (iii) the Poisson’s equations for gravity and magnetic potential fields. Under the model assumptions, a generic unrest of 1-year engenders on the ground surface low amplitude changes in the investigated geophysical observables, that are, however, above the accuracies of the modern

Learning about Hydrothermal Volcanic Activity by Modeling Induced Geophysical Changes

Directory of Open Access Journals (Sweden)

Gilda M. Currenti

2017-05-01

Full Text Available Motivated by ongoing efforts to understand the nature and the energy potential of geothermal resources, we devise a coupled numerical model (hydrological, thermal, mechanical, which may help in the characterization and monitoring of hydrothermal systems through computational experiments. Hydrothermal areas in volcanic regions arise from a unique combination of geological and hydrological features which regulate the movement of fluids in the vicinity of magmatic sources capable of generating large quantities of steam and hot water. Numerical simulations help in understanding and characterizing rock-fluid interaction processes and the geophysical observations associated with them. Our aim is the quantification of the response of different geophysical observables (i.e., deformation, gravity, and magnetic fields to hydrothermal activity on the basis of a sound geological framework (e.g., distribution and pathways of the flows, the presence of fractured zones, caprock. A detailed comprehension and quantification of the evolution and dynamics of the geothermal systems and the definition of their internal state through a geophysical modeling approach are essential to identify the key parameters for which the geothermal system may fulfill the requirements to be exploited as a source of energy. For the sake of illustration only, the numerical computations are focused on a conceptual model of the hydrothermal system of Vulcano Island by simulating a generic 1-year unrest and estimating different geophysical changes. We solved (i the mass and energy balance equations of flow in porous media for temperature, pressure and density changes, (ii the elastostatic equation for the deformation field and (iii the Poisson's equations for gravity and magnetic potential fields. Under the model assumptions, a generic unrest of 1-year engenders on the ground surface low amplitude changes in the investigated geophysical observables, that, being above the accuracies of

Electric Dipole Echoes and Noise-Induced Coherence

International Nuclear Information System (INIS)

Mestayer, J.J.; Zhao, W.; Lancaster, J.C.; Dunning, F.B.; Yoshida, S.; Reinhold, Carlos O.; Burgdorfer, J.

2007-01-01

The generation of echoes in the electric dipole moment of a Rydberg wavepacket precessing in an external electric field by reversal of the field is described. When the wavepacket experiences reversible dephasing, large echoes are observed pointing to strong refocusing of the wavepacket. The presence of irreversible dephasing leads to a reduction in the size of the echoes. The effect of irreversible dynamics on echoes is investigated using artificially synthesized noise. Methods to determine the decoherence rate are discussed

Beam echoes in the presence of coupling

Energy Technology Data Exchange (ETDEWEB)

Gross, Axel [Case Western Reserve U.

2017-10-03

Transverse beam echoes could provide a new technique of measuring diusion characteristics orders of magnitude faster than the current methods; however, their interaction with many accelerator parameters is poorly understood. Using a program written in C, we explored the relationship between coupling and echo strength. We found that echoes could be generated in both dimensions, even with a dipole kick in only one dimension. We found that the echo eects are not destroyed even when there is strong coupling, falling o only at extremely high coupling values. We found that at intermediate values of skew quadrupole strength, the decoherence time of the beam is greatly increased, causing a destruction of the echo eects. We found that this is caused by a narrowing of the tune width of the particles. Results from this study will help to provide recommendations to IOTA (Integrable Optics Test Accelerator) for their upcoming echo experiment.

Geophysics of Geothermal Areas: State of the Art and Future Development

Science.gov (United States)

Mabey, Don R.

In May 1980 a workshop organized by the Advanced School of Geophysics of the Ettore Majorana Center for Scientific Culture was held in Erice, Italy. The purpose was to present the state of the art and future development of geophysics as related to exploration for geothermal resources and the environmental impact of the development of geothermal systems. The workshop was addressed to “younger researchers working in scientific institutions and in public or private agencies and who are particularly interested in these aspects of the energy problem.” Fourteen formal lectures were presented to the workshop. This volume contains papers based on 10 of these lectures with a preface, forward, and introduction by the editors. The ten papers are “Heat Transfer in Geothermal Areas,” “Interpretation of Conductive Heat Flow Anomalies,” “Deep Electromagnetic Soundings in Geothermal Exploration,” “A Computation Method for dc Geoelectric Fields,” “Measurement of Ground Deformation in Geothermal Areas,” “Active Seismic Methods in Geothermal Exploration,” “The Role of Geophysical Investigations in the Discovery of the Latera Geothermal Field,” “Geothermal Resources Exploration in the European Community: The Geophysical Case,” “Activity Performed by AGIP (ENI Group) in the Field of Geothermal Energy,” and “Geothermal Exploration in the Western United States.” Six of the authors are from Italy, and one each is from Iceland, the Netherlands, West Germany, and the United States. All of the papers are in English.

Geophysical Field Theory

International Nuclear Information System (INIS)

Eloranta, E.

2003-11-01

The geophysical field theory includes the basic principles of electromagnetism, continuum mechanics, and potential theory upon which the computational modelling of geophysical phenomena is based on. Vector analysis is the main mathematical tool in the field analyses. Electrostatics, stationary electric current, magnetostatics, and electrodynamics form a central part of electromagnetism in geophysical field theory. Potential theory concerns especially gravity, but also electrostatics and magnetostatics. Solid state mechanics and fluid mechanics are central parts in continuum mechanics. Also the theories of elastic waves and rock mechanics belong to geophysical solid state mechanics. The theories of geohydrology and mass transport form one central field theory in geophysical fluid mechanics. Also heat transfer is included in continuum mechanics. (orig.)

Geophysical investigations in the Veitsivaara area, Finland summary report

International Nuclear Information System (INIS)

Heikkinen, E.; Saksa, P.; Hinkkanen, H.

1991-10-01

Teollisuuden Voima Oy (TVO carries out site investigations in Finland for final disposal of nuclear high level waste during 1987-2000. Investigations by geological, geophysical, geohydrological and geochemical methods were carried out in the Veitsivaara area in 1987-90 to determine the suitability of the bedrock for the final disposal of spent nuclear fuel. Airborne, ground and borehole geophysical methods were used to study the rock type distribution, fracturing and hydraulic conductivity. Airborne surveys were performed by magnetic, radiometric and two electromagnetic methods and ground investigations by VLF magnetic and resistivity, magnetic and impulse radar methods. Electromagnetic and seismic refraction surveys were used to locate crushed and fracture zones. The properties of weak electrical conductors, e.g. their depth dimensions, were studied by direct current resistivity measurements. The rock type distribution was studied by single-hole logging of susceptibility, natural γ-radiation and radiometric γ γ-density. Electrical and acoustic logging allowed water bearing fractures to be mapped and the results of water injection tests to be interpreted. Flow conditions in the boreholes were studied by both fluid logging and tube wave sounding

Use of geophysical methods to characterize groundwater in karstic rocks near Puerto Morelos, Yucatan Peninsula, Mexico

Science.gov (United States)

cerda Garcia, C. G.; Carpenter, P. J.; Leal-Bautista, R. M.

2017-12-01

Geophysical surveys were used to determine the depth of the freshwater/saltwater interface and groundwater preferential flow pathways along the Ruta de los Cenotes, near Puerto Morelos (northeast part of the Yucatán peninsula). The Yucatán Peninsula is a limestone platform that allows quick recharge of the aquifer, the main supply of water for this region. The water in the aquifer is divided into freshwater and saltwater zones. A Schlumberger resistivity sounding along the road near one cenote suggests the water table is 5 meters deep and the freshwater/saltwater interface is 38 meters deep. A time-domain electromagnetic (TEM) sounding suggests the freshwater/saltwater interface is 45 meters deep. The depth of the interface determines the volume of fresh water available. Preferential flow pathways in the vadose and saturated zones are karst conduits where groundwater percolates downward in the vadose zone. These were identified using resistivity profiling and spontaneous self-potential (SP) geophysical methods. Interpretation of SP profile Line SP1, located 3 m south of the cenote, suggests two fractures, which appear to extend south as far as SP profile Line SP2, 15 m south of the cenote; both lines are parallel to each other. SP anomalies suggest water flow along these fractures. The use of noninvasive geophysical methods, specifically SP, resistivity and TEM are useful for exploring the karst system in the Yucatán peninsula.

Fundamentals of Geophysics

Science.gov (United States)

Lowrie, William

1997-10-01

This unique textbook presents a comprehensive overview of the fundamental principles of geophysics. Unlike most geophysics textbooks, it combines both the applied and theoretical aspects to the subject. The author explains complex geophysical concepts using abundant diagrams, a simplified mathematical treatment, and easy-to-follow equations. After placing the Earth in the context of the solar system, he describes each major branch of geophysics: gravitation, seismology, dating, thermal and electrical properties, geomagnetism, paleomagnetism and geodynamics. Each chapter begins with a summary of the basic physical principles, and a brief account of each topic's historical evolution. The book will satisfy the needs of intermediate-level earth science students from a variety of backgrounds, while at the same time preparing geophysics majors for continued study at a higher level.

A Bayesian trans-dimensional approach for the fusion of multiple geophysical datasets

Science.gov (United States)

JafarGandomi, Arash; Binley, Andrew

2013-09-01

We propose a Bayesian fusion approach to integrate multiple geophysical datasets with different coverage and sensitivity. The fusion strategy is based on the capability of various geophysical methods to provide enough resolution to identify either subsurface material parameters or subsurface structure, or both. We focus on electrical resistivity as the target material parameter and electrical resistivity tomography (ERT), electromagnetic induction (EMI), and ground penetrating radar (GPR) as the set of geophysical methods. However, extending the approach to different sets of geophysical parameters and methods is straightforward. Different geophysical datasets are entered into a trans-dimensional Markov chain Monte Carlo (McMC) search-based joint inversion algorithm. The trans-dimensional property of the McMC algorithm allows dynamic parameterisation of the model space, which in turn helps to avoid bias of the post-inversion results towards a particular model. Given that we are attempting to develop an approach that has practical potential, we discretize the subsurface into an array of one-dimensional earth-models. Accordingly, the ERT data that are collected by using two-dimensional acquisition geometry are re-casted to a set of equivalent vertical electric soundings. Different data are inverted either individually or jointly to estimate one-dimensional subsurface models at discrete locations. We use Shannon's information measure to quantify the information obtained from the inversion of different combinations of geophysical datasets. Information from multiple methods is brought together via introducing joint likelihood function and/or constraining the prior information. A Bayesian maximum entropy approach is used for spatial fusion of spatially dispersed estimated one-dimensional models and mapping of the target parameter. We illustrate the approach with a synthetic dataset and then apply it to a field dataset. We show that the proposed fusion strategy is

Application of Surface Geophysical Methods, With Emphasis on Magnetic Resonance Soundings, to Characterize the Hydrostratigraphy of the Brazos River Alluvium Aquifer, College Station, Texas, July 2006 - A Pilot Study

Science.gov (United States)

Shah, Sachin D.; Kress, Wade H.; Legchenko, Anatoly

2007-01-01

The U.S. Geological Survey, in cooperation with the Texas Water Development Board, used surface geophysical methods at the Texas A&M University Brazos River Hydrologic Field Research Site near College Station, Texas, in a pilot study, to characterize the hydrostratigraphic properties of the Brazos River alluvium aquifer and determine the effectiveness of the methods to aid in generating an improved ground-water availability model. Three non-invasive surface geophysical methods were used to characterize the electrical stratigraphy and hydraulic properties and to interpret the hydrostratigraphy of the Brazos River alluvium aquifer. Two methods, time-domain electromagnetic (TDEM) soundings and two-dimensional direct-current (2D-DC) resistivity imaging, were used to define the lateral and vertical extent of the Ships clay, the alluvium of the Brazos River alluvium aquifer, and the underlying Yegua Formation. Magnetic resonance sounding (MRS), a recently developed geophysical method, was used to derive estimates of the hydrologic properties including percentage water content and hydraulic conductivity. Results from the geophysics study demonstrated the usefulness of combined TDEM, 2D-DC resistivity, and MRS methods to reduce the need for additional boreholes in areas with data gaps and to provide more accurate information for ground-water availability models. Stratigraphically, the principal finding of this study is the relation between electrical resistivity and the depth and thickness of the subsurface hydrostratigraphic units at the site. TDEM data defined a three-layer electrical stratigraphy corresponding to a conductor-resistor-conductor that represents the hydrostratigraphic units - the Ships clay, the alluvium of the Brazos River alluvium aquifer, and the Yegua Formation. Sharp electrical boundaries occur at about 4 to 6 and 20 to 22 meters below land surface based on the TDEM data and define the geometry of the more resistive Brazos River alluvium aquifer

X-ray echoes from gamma-ray bursts

International Nuclear Information System (INIS)

Dermer, C.D.; Hurley, K.C.; Hartmann, D.H.

1991-01-01

The identification of an echo of reflected radiation in time histories of gamma-ray burst spectra can provide important information about the existence of binary companions or accretion disks in gamma-ray burst systems. Because of the nature of Compton scattering, the spectrum of the echo will be attenuated at gamma-ray energies compared with the spectrum of the primary burst emission. The expected temporal and spectral signatures of the echo and a search for such echoes are described, and implications for gamma-ray burst models are discussed. 35 refs

The French balloon and sounding rocket space program

Science.gov (United States)

Coutin/Faye, S.; Sadourny, I.

1987-08-01

Stratospheric and long duration flight balloon programs are outlined. Open stratospheric balloons up to 1 million cu m volume are used to carry astronomy, solar system, aeronomy, stratosphere, biology, space physics, and geophysics experiments. The long duration balloons can carry 50 kg payloads at 20 to 30 km altitude for 10 days to several weeks. Pressurized stratospheric balloons, and infrared hot air balloons are used. They are used to study the dynamics of stratospheric waves and atmospheric water vapor. Laboratories participating in sounding rocket programs are listed.

Geophysical borehole logging

International Nuclear Information System (INIS)

McCann, D.; Barton, K.J.; Hearn, K.

1981-08-01

Most of the available literature on geophysical borehole logging refers to studies carried out in sedimentary rocks. It is only in recent years that any great interest has been shown in geophysical logging in boreholes in metamorphic and igneous rocks following the development of research programmes associated with geothermal energy and nuclear waste disposal. This report is concerned with the programme of geophysical logging carried out on the three deep boreholes at Altnabreac, Caithness, to examine the effectiveness of these methods in crystalline rock. Of particular importance is the assessment of the performance of the various geophysical sondes run in the boreholes in relation to the rock mass properties. The geophysical data can be used to provide additional in-situ information on the geological, hydrogeological and engineering properties of the rock mass. Fracturing and weathering in the rock mass have a considerable effect on both the design parameters for an engineering structure and the flow of water through the rock mass; hence, the relation between the geophysical properties and the degree of fracturing and weathering is examined in some detail. (author)

HMF-Geophysics - An Update

Science.gov (United States)

Crook, N.; Knight, R.; Robinson, D.

2007-12-01

There is growing recognition of the challenges we face, in many parts of the world, in finding and maintaining clean sources of water for human consumption and agricultural use, while balancing the needs of the natural world. Advancements in hydrologic sciences are needed in order to develop an improved understanding of the controls on the quantity, movement, and quality of water, thus enhancing our ability to better protect and manage our water resources. Geophysical methods can play a central role in these investigations. CUAHSI (Consortium of Universities for the Advancement of Hydrologic Sciences) is developing, with the support of the National Science Foundation, a Hydrologic Measurement Facility (HMF), which contains a Geophysics module, referred to as HMF-Geophysics. The Geophysics module will support and advance the use of geophysics for hydrologic applications. Currently in second year of a 3 year pilot study, the main aim of HMF-Geophysics is to develop the infrastructure necessary to provide geophysical techniques and the expertise to apply them correctly for the hydrological community. The current working model consists of a central HMF-Geophysics facility and a number of volunteer nodes. The latter consists of individuals at universities who have volunteered to be part of HMF-Geophysics by using their equipment, and/or software, and expertise, in research partnerships with hydrologists. In response to an inquiry the central facility takes on the evaluation of the potential of geophysics to the area of research/watershed. The central facility can then undertake a feasibility study to determine how/if geophysical methods could be of use, and to evaluate the "value-added" by geophysics to the science. Once it is clear that the geophysics can contribute in a significant way to addressing the science questions the central facility works with the hydrologist to set up the next step. Our assumption is that at this point, the hydrologist (perhaps with a

Anti-bat tiger moth sounds: Form and function

Directory of Open Access Journals (Sweden)

Aaron J. CORCORAN, William E. CONNER, Jesse R. BARBER

2010-06-01

Full Text Available The night sky is the venue of an ancient acoustic battle between echolocating bats and their insect prey. Many tiger moths (Lepidoptera: Arctiidae answer the attack calls of bats with a barrage of high frequency clicks. Some moth species use these clicks for acoustic aposematism and mimicry, and others for sonar jamming, however, most of the work on these defensive functions has been done on individual moth species. We here analyze the diversity of structure in tiger moth sounds from 26 species collected at three locations in North and South America. A principal components analysis of the anti-bat tiger moth sounds reveals that they vary markedly along three axes: (1 frequency, (2 duty cycle (sound production per unit time and frequency modulation, and (3 modulation cycle (clicks produced during flexion and relaxation of the sound producing tymbal structure. Tiger moth species appear to cluster into two distinct groups: one with low duty cycle and few clicks per modulation cycle that supports an acoustic aposematism function, and a second with high duty cycle and many clicks per modulation cycle that is consistent with a sonar jamming function. This is the first evidence from a community-level analysis to support multiple functions for tiger moth sounds. We also provide evidence supporting an evolutionary history for the development of these strategies. Furthermore, cross-correlation and spectrogram correlation measurements failed to support a “phantom echo” mechanism underlying sonar jamming, and instead point towards echo interference [Current Zoology 56 (3: 358–369, 2010].

Geophysical investigations of geology and structure at the Martis Creek Dam, Truckee, California

Science.gov (United States)

Bedrosian, P.A.; Burton, B.L.; Powers, M.H.; Minsley, B.J.; Phillips, J.D.; Hunter, L.E.

2012-01-01

A recent evaluation of Martis Creek Dam highlighted the potential for dam failure due to either seepage or an earthquake on nearby faults. In 1972, the U.S. Army Corps of Engineers constructed this earthen dam, located within the Truckee Basin to the north of Lake Tahoe, CA for water storage and flood control. Past attempts to raise the level of the Martis Creek Reservoir to its design level have been aborted due to seepage at locations downstream, along the west dam abutment, and at the base of the spillway. In response to these concerns, the U.S. Geological Survey has undertaken a comprehensive suite of geophysical investigations aimed at understanding the interplay between geologic structure, seepage patterns, and reservoir and groundwater levels. This paper concerns the geologic structure surrounding Martis Creek Dam and emphasizes the importance of a regional-scale understanding to the interpretation of engineering-scale geophysical data. Our studies reveal a thick package of sedimentary deposits interbedded with Plio-Pleistocene volcanic flows; both the deposits and the flows are covered by glacial outwash. Magnetic field data, seismic tomography models, and seismic reflections are used to determine the distribution and chronology of the volcanic flows. Previous estimates of depth to basement (or the thickness of the interbedded deposits) was 100 m. Magnetotelluric soundings suggest that electrically resistive bedrock may be up to 2500 m deep. Both the Polaris Fault, identified outside of the study area using airborne LiDAR, and the previously unnamed Martis Creek Fault, have been mapped through the dam area using ground and airborne geophysics. Finally, as determined by direct-current resistivity imaging, time-domain electromagnetic sounding, and seismic refraction, the paleotopography of the interface between the sedimentary deposits and the overlying glacial outwash plays a principal role both in controlling groundwater flow and in the distribution of the

MEASUREMENT OF TRANSVERSE ECHOES IN RHIC

International Nuclear Information System (INIS)

FISCHER, W.; SATOGATA, T.; TOMAS, R.

2005-01-01

Beam echoes are a very sensitive method to measure diffusion, and longitudinal echo measurements were performed in a number of machines. In RHIC, for the first time, a transverse beam echo was observed after applying a dipole kick followed by a quadrupole .kick. After application of the dipole kick, the dipole moment decohered completely due to lattice nonlinearities. When a quadrupole kick is applied at time τ after the dipole kick, the beam re-cohered at time 2τ thus showing an echo response. We describe the experimental setup and measurement results. In the measurements the dipole and quadrupole kick amplitudes, amplitude dependent tune shift, and the time between dipole and quadrupole kick were varied. In addition, measurements were taken with gold bunches of different intensities. These should exhibit different transverse diffusion rates due to intra-beam scattering

Time-resolved Femtosecond Photon Echo Probes Bimodal Solvent Dynamics

NARCIS (Netherlands)

Pshenichnikov, M.S; Duppen, K.; Wiersma, D. A.

1995-01-01

We report on time-resolved femtosecond photon echo experiments of a dye molecule in a polar solution. The photon echo is time resolved by mixing the echo with a femtosecond gate pulse in a nonlinear crystal. It is shown that the temporal profile of the photon echo allows separation of the

Depth study of insular shelf electric sounding Adelaida anomaly (Rivera)[Geochemical prospection of Uranium in Uruguay]; Estudio de la profundidad del zocalo por sondeos electricos Anomalia Adelaida (Rivera)

Energy Technology Data Exchange (ETDEWEB)

Cicalese, H

1983-07-01

In the framework of the Uranium prospecting programme, the DINAMIGE geophysical equipment have made a study. It was about the depth of insular shelf electric sounding on the anomalies zone of Adelaida. This equipment carried out a study of the following subjects: geographical location, geologic framework, geophysical intervention, developed works, methods and material and results.

Gravitational wave sources: reflections and echoes

Science.gov (United States)

Price, Richard H.; Khanna, Gaurav

2017-11-01

The recent detection of gravitational waves has generated interest in alternatives to the black hole interpretation of sources. A subset of such alternatives involves a prediction of gravitational wave ‘echoes’. We consider two aspects of possible echoes: first, general features of echoes coming from spacetime reflecting conditions. We find that the detailed nature of such echoes does not bear any clear relationship to quasi-normal frequencies. Second, we point out the pitfalls in the analysis of local reflecting ‘walls’ near the horizon of rapidly rotating black holes.

Gravitational wave sources: reflections and echoes

International Nuclear Information System (INIS)

Price, Richard H; Khanna, Gaurav

2017-01-01

The recent detection of gravitational waves has generated interest in alternatives to the black hole interpretation of sources. A subset of such alternatives involves a prediction of gravitational wave ‘echoes’. We consider two aspects of possible echoes: first, general features of echoes coming from spacetime reflecting conditions. We find that the detailed nature of such echoes does not bear any clear relationship to quasi-normal frequencies. Second, we point out the pitfalls in the analysis of local reflecting ‘walls’ near the horizon of rapidly rotating black holes. (paper)

Sparse adaptive filters for echo cancellation

CERN Document Server

Paleologu, Constantin

2011-01-01

Adaptive filters with a large number of coefficients are usually involved in both network and acoustic echo cancellation. Consequently, it is important to improve the convergence rate and tracking of the conventional algorithms used for these applications. This can be achieved by exploiting the sparseness character of the echo paths. Identification of sparse impulse responses was addressed mainly in the last decade with the development of the so-called ``proportionate''-type algorithms. The goal of this book is to present the most important sparse adaptive filters developed for echo cancellati

Liver iron content determined by MRI. Spin-echo vs. gradient-echo

Energy Technology Data Exchange (ETDEWEB)

Juchems, M.S.; Wunderlich, A.P. [Universitaetskliniken Ulm (Germany). Klinik fuer Diagnostische und Interventionelle Radiologie; Cario, H. [Universitaetskliniken Ulm (Germany). Klinik fuer Kinder- und Jugendmedizin; Schmid, M. [Stadtspital Triemli, Zuerich (Switzerland). Medizinische Onkologie und Haematologie

2012-05-15

Purpose: Liver iron content (LIC) measurement plays a central role in the management of patients with transfusional iron overload. Calculating the LIC with data obtained from standardized MRI sequences represents an attractive alternative diagnostic possibility. The purpose of this study was to compare the LIC measurement obtained with gradient-echo (GRE) sequences to the mean liver proton transverse relaxation (R2) acquired with SE sequences. Materials and Methods: 68 patients with iron overload (median age: 24, range: 3 - 88) underwent 1.5 T MRI for liver iron content measurement. All patients received spin-echo (SE) and gradient-echo (GRE) sequences. Results: The two MRI methods revealed different liver iron content results although a significant correlation was found (r = 0.85, p < 0.001). Values evaluated using GRE sequences (median: 260 {mu}mol/g dry weight [d.w.], range: 6 - 732) were generally higher than those obtained by SE examinations (median: 161 {mu}mol /g d.w., range: 5 - 830). Conclusion: In conclusion, our study revealed different results for both MRI measurements, which could lead to different decisions concerning the management of chelation therapy in individual patients. (orig.)

Evaluation of cardiac function using multi-shot echo planar imaging

Energy Technology Data Exchange (ETDEWEB)

Nakanishi, Tadashi; Tanitame, Nobuko; Hata, Ryoichiro; Hirai, Nobuhiko; Ikeda, Midori; Ono, Chiaki; Fukuoka, Haruhito; Ito, Katsuhide [Hiroshima Univ. (Japan). School of Medicine

1998-01-01

In this study, we performed multi-shot echo planar imaging (8 shot, TR/TE/FL=55 ms/18 ms/60 degrees) and k-space segmented fast gradient echo sequence (8 views per segment, TR/TE/FL=9.9 ms/1.8 ms/30 degrees) to assess cardiac function in healthy volunteers. Transaxial sections of the entire heart were obtained with both sequences in ECG triggered, breath hold, and with a 256 x 128 matrix. Resulting temporal resolution was 55 ms for echo planar imaging, and 71 ms for k-space segmented fast gradient echo sequence, respectively. Ventricular volume and ejection fraction of both ventricles and left ventricular mass obtained with multi-shot echo planar imaging were assessed in comparison with k-space segmented fast gradient echo sequence. Measurements of left ventricular volume, ejection fraction and mass obtained with multi-shot echo planar imaging demonstrated close correlation with those obtained with k-space segmented fast gradient echo sequence. Right ventricular volumes obtained with echo planar imaging were significantly higher than those obtained with k-space segmented fast gradient echo sequence. This tendency is considered to be due to differing contrast between right ventricular myocardium and fat tissue observed with echo planar imaging relative to that observed with fast gradient echo sequence, because fat suppression is always performed in echo planar images. Multi-shot echo planar imaging can be a reliable tool for measurement of cardiac functional parameters, although wall motion analysis of the left ventricle requires higher temporal resolution and a short axial section. (K.H.)

Mock ECHO: A Simulation-Based Medical Education Method.

Science.gov (United States)

Fowler, Rebecca C; Katzman, Joanna G; Comerci, George D; Shelley, Brian M; Duhigg, Daniel; Olivas, Cynthia; Arnold, Thomas; Kalishman, Summers; Monnette, Rebecca; Arora, Sanjeev

2018-04-16

This study was designed to develop a deeper understanding of the learning and social processes that take place during the simulation-based medical education for practicing providers as part of the Project ECHO® model, known as Mock ECHO training. The ECHO model is utilized to expand access to care of common and complex diseases by supporting the education of primary care providers with an interprofessional team of specialists via videoconferencing networks. Mock ECHO trainings are conducted through a train the trainer model targeted at leaders replicating the ECHO model at their organizations. Trainers conduct simulated teleECHO clinics while participants gain skills to improve communication and self-efficacy. Three focus groups, conducted between May 2015 and January 2016 with a total of 26 participants, were deductively analyzed to identify common themes related to simulation-based medical education and interdisciplinary education. Principal themes generated from the analysis included (a) the role of empathy in community development, (b) the value of training tools as guides for learning, (c) Mock ECHO design components to optimize learning, (d) the role of interdisciplinary education to build community and improve care delivery, (e) improving care integration through collaboration, and (f) development of soft skills to facilitate learning. Mock ECHO trainings offer clinicians the freedom to learn in a noncritical environment while emphasizing real-time multidirectional feedback and encouraging knowledge and skill transfer. The success of the ECHO model depends on training interprofessional healthcare providers in behaviors needed to lead a teleECHO clinic and to collaborate in the educational process. While building a community of practice, Mock ECHO provides a safe opportunity for a diverse group of clinician experts to practice learned skills and receive feedback from coparticipants and facilitators.

MR imaging of articular cartilage : comparison of magnetization transfer contrast and fat-suppression in multiplanar and 3D gradient-echo, spin-echo, turbo spin-echo techniques

International Nuclear Information System (INIS)

Lee, Young Joon; Joo, Eun Young; Eun, Choong Ki

1999-01-01

The purpose of this study was to evaluate the effects of magnetization transfer contrast(MTC) and fat-suppression(FS) in variable spin-echo and gradient-echo sequences for articular cartilage imaging and to determine the optimal pulse sequences. Using variable 7-pulse sequences, the knees of 15 pigs were imaged Axial images were obtained using proton density and T2-weighted spin-echo (PDWSE and T2WSE), turbo spin-echo (TSE), multiplanar gradient-echo (MPGR), and 3D steady-state gradient-echo (3DGRE) sequences, and the same pulse sequences were then repeated using MTC. Also T1-weighted spin-echo(T1WSE) and 3D spoiled gradient-echo(3DSPGR) images of knees were also acquired, and the procedure was repeated using FS. For each knee, a total of 14 axial images were acquired, and using a 6-band scoring system, the visibility of and the visibilities of the the articular cartilage was analyzed. The visual effect of MTC and FS was scored using a 4-band scale. For each image, the signal intensities of articular cartilage, subchondral bone, muscles, and saline were measured, and signal-to-noise ratios(SNR) and contrast-to-noise ratios(CNR) were also calculated. Visibility of the cartilage was best when 3DSPGR and T1WSE sequences were used. MTC imaging increased the negative contrast between cartilage and saline, but FS imaging provided more positive contrast. CNR between cartilage and saline was highest when using TSE with FS(-351.1±15.3), though CNR between cartilage and bone then fell to -14.7±10.8. In MTC imaging using MPGR showed the greatest increase of negative contrast between cartilage and saline(CNR change=-74.7); the next highest was when 3DGRE was used(CNR change=-34.3). CNR between cartilage and bone was highest with MPGR(161.9±17.7), but with MTC, the greatest CNR decrease(-81.8) was observed. The greatest CNR increase between cartilage and bone was noted in T1WSE with FS. In all scans, FS provided a cartilage-only positive contrast image, though the absolute

Echo 2: a study of electron beams injected into the high-latitude ionosphere from a large sounding rocket

International Nuclear Information System (INIS)

Winckler, J.R.; Arnoldy, R.L.; Hendrickson, R.A.

1975-01-01

The Black Brant V-C Echo 2 rocket was launched at Fort Churchill on September 25, 1972, and it injected 64-ms pulses of electron beams of 80-mA current and 45-keV voltage into the ionosphere. This paper studies the responses of on-board electrostatic deflection and solid state detectors to injected electrons after motion in the near ionosphere and atmosphere. It is shown that it was only through some form of scattering that the detectors could sense the injected beam electrons. By means of 'phase maps' of injection and detection pitch angles a number of distinct regions are found corresponding to a rocket scattering halo, an atmospheric scattering halo, a region of weak responses, and a source of strong scattering above the rocket. The atmospheric scattering has been compared with the theoretical and experimental results of the Echo 1 experiment, and it is found to be in reasonable agreement. The rocket halo is discussed qualitatively; but no explanation is found for the backscatter from above the rocket, which may be associated with an occasional violent beam instability. This analysis has been carried out to better understand the complexities of electron motion observed near large rockets carrying artifical electron accelerators as a guide in the planning of future experiments

The effect of strong pitch angle scattering on the use of artificial auroral streaks for echo detection - Echo 5

International Nuclear Information System (INIS)

Swanson, R.L.; Steffen, J.E.; Winckler, J.R.

1986-01-01

During the Echo 5 experiment launched 13 November 1979 from the Poker Flat Research Range (Fairbanks, Alaska), a 0.75 A, 37 keV electron beam was injected both up and down the field line to test the use of optical and X-ray methods to detect the beam as it interacted with the atmosphere below the rocket for both the downward injections (markers) and the upward injected electrons which mirrored at the Southern Hemisphere and returned echoes. The artificial auroral streaks created by the markers were easily visible on the ground TV system but the large intensity of photons produced around the rocket masked any response to the markers by the on-board photometers and X-ray detectors. No echoes were detected with any of the detection systems although the power in some of the upward injections was 7.6 times the power in a detected downward injection thus setting an upper limit on the loss-cone echo flux. The magnitude of the bounce averaged pitch angle diffusion coefficient necessary to explain the lack of observable echoes was found to be 4 x 10 -4 S -1 . It was found that an equatorial wave electric field of 11 mVm -1 would account for the lack of echoes. Such fields should cause strong pitch angle scattering of up to 10 keV natural electrons and thus be consistent with the presence of diffuse aurora on the Echo 5 trajectory. (author)

Assessment of geothermal energy potential by geophysical methods: Nevşehir Region, Central Anatolia

Science.gov (United States)

Kıyak, Alper; Karavul, Can; Gülen, Levent; Pekşen, Ertan; Kılıç, A. Rıza

2015-03-01

In this study, geothermal potential of the Nevşehir region (Central Anatolia) was assessed by using vertical electrical sounding (VES), self-potential (SP), magnetotelluric (MT), gravity and gravity 3D Euler deconvolution structure analysis methods. Extensive volcanic activity occurred in this region from Upper Miocene to Holocene time. Due to the young volcanic activity Nevşehir region can be viewed as a potential geothermal area. We collected data from 54 VES points along 5 profiles, from 28 MT measurement points along 2 profiles (at frequency range between 320 and 0.0001 Hz), and from 4 SP profiles (total 19 km long). The obtained results based on different geophysical methods are consistent with each other. Joint interpretation of all geological and geophysical data suggests that this region has geothermal potential and an exploration well validated this assessment beyond doubt.

SOUND VELOCITY and Other Data from FIXED PLATFORM and Other Platforms From NE Atlantic (limit-40 W) and Others from 19860512 to 19891112 (NODC Accession 9000121)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The sound velocity and other data in this accession has been processed by NODC from a tape submitted by the originator containing Inverted Echo Sounder data from the...

Application of comprehensive geophysical methods to prospecting for sandstone-type uranium deposit in Bayanmaodu basin

International Nuclear Information System (INIS)

Yao Yifeng; Sun Zexuan; Chen Zhiguo; He Tao; Li Guoxin

2003-01-01

By using comprehensive geophysical methods including magnetic survey, resistivity sounding, self potential survey, 210 Po survey etc., the shape and the depth of the basement, the structure of the sedimentary cover, characteristics of prospecting target horizon, the development of interlayer oxidation zone at depth, as well as the information of uranium mineralization have been basically revealed, thus providing a basis for the prospect evaluation of sandstone-type uranium mineralization in the basin

Magnetotelluric soundings on the Idaho National Engineering Laboratory facility, Idaho

International Nuclear Information System (INIS)

Stanley, W.D.

1982-01-01

The magnetotelluric (MT) method was used as one of several geophysical tools to study part of the Idaho Engineering Laboratory (INEL) facility. The purpose of the geophysical study on INEL was to investigate the facility for a possible site to drill a geothermal exploration well. The initial interpretation of the MT sounding data was done with one-dimensional models consisting of four or five layers, the minimum number required to fit the data. After the test well (INEL-1) was completed, the electric log was used to guide an improved one-dimensional ID interpretation of the MT sounding data. Profile models derived from the well log provided good agreement with velocity models derived from refraction seismic data. A resolution study using generalized inverse techniques shows that the resolution of resistive layers in the lower part of the MT models is poor, as is the definition of a shallow, altered basalt unit. The only major structure observed on the MT data was the faulted contact between the SNRP and basin and range structures on the west. Modeling of the data near this structure with a two-dimensional computer program showed that the MT data near the fault require a model similar to the seismic refraction models and that structure on a deep crustal conductor is also required

Geophysical investigations of the Romuvaara area, Finland

International Nuclear Information System (INIS)

Saksa, P.; Paananen, M.

1991-06-01

In the study area of Romuvaara, investigations have been carried out during 1987 - 90 with the aim of finding out whether the polyphasically deformed Precambrian gneiss complex is suitable for the final disposal of spent nuclear fuel. The bedrock has been studied by geological, geophysical, geohydrological and geochemical methods. Airborne, ground and borehole geophysical surveys were used in studying the rock type distribution, fracturing and hydraulic conductivity of the bedrock to a depth of one kilometre. Airborne surveys (magnetic, radiometric and two electromagnetic methods) and ground surveys (VLF and VLF-R, magnetic and soil radar methods) were useful in distinguishing the metadiabases, amphibolites and granodiorites from the less magnetized migmatites. The electromagnetic and seismic refraction surveys were used in locating crushed and fractured zones. The rock type distribution was studied by single-hole logging of susceptibility, natural γ radiation and radiometric γ-γ -density. Electrical and acoustic logging served the mapping of fractures and the interpretation of water injection tests. The flow conditions in the boreholes were studied by fluid logging and tube-wave sounding. The rock volume surrounding the boreholes was mapped by borehole radar with a frequency of 22 MHz. The upper parts of the boreholes were also studied by vertical radar profiling (VRP). Larger volumes of rock were mapped by vertical seismic profiling (VSP) using 4 - 5 transmitter shotholes per borehole

Echo-Interleaved-Spiral MR Imaging

International Nuclear Information System (INIS)

Rosenthal, Shirrie; Azhari, Haim; Montag, Avram

1998-01-01

Interleaved-Spiral imaging is an efficient method for MRI fast scans. However, images suffer from blurring and artifacts due to field inhomogeneities and the long readout times. In this paper, we combine interleaved-spirals with spin-echo for 3D scans. The refocusing RF-pulses (echoes) refocus off-resonance spins, thus allowing longer acquisition times per excitation, by limiting inhomogeneity effects. The total number of excitations for a 3D scan is reduced by half. The 3D Fourier transform of an object is divided into pairs of slices, one slice is scanned in an outgoing interleaved-spiral, initiated after a 90 degree pulse has been applied. The second slice is scanned in an ingoing interleaved-spiral, after a 180 degree pulse has been applied, thus reaching the slice origin at the echo time. (authors)

Geophysics

CERN Document Server

Bolt, Bruce

1973-01-01

Methods in Computational Physics, Volume 13: Geophysics is a 10-chapter text that focuses with the theoretical solid-earth geophysics. This volume specifically covers the general topics of terrestrial magnetism and electricity, the Earth's gravity field, tidal deformations, dynamics of global spin, spin processing, and convective models for the deep interior. This volume surveys first the construction of mathematical models, such as the representation of the geomagnetic field by assuming arrangements of multipole sources in the core and the fast computer evaluation of two- and three-dimensiona

Time Delay Estimation Algoritms for Echo Cancellation

Directory of Open Access Journals (Sweden)

Kirill Sakhnov

2011-01-01

Full Text Available The following case study describes how to eliminate echo in a VoIP network using delay estimation algorithms. It is known that echo with long transmission delays becomes more noticeable to users. Thus, time delay estimation, as a part of echo cancellation, is an important topic during transmission of voice signals over packetswitching telecommunication systems. An echo delay problem associated with IP-based transport networks is discussed in the following text. The paper introduces the comparative study of time delay estimation algorithm, used for estimation of the true time delay between two speech signals. Experimental results of MATLab simulations that describe the performance of several methods based on cross-correlation, normalized crosscorrelation and generalized cross-correlation are also presented in the paper.

summarytable.PNG | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Resources.PNG | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Custom Search | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Watershed Statistics | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Advances in geophysics

CERN Document Server

Sato, Haruo

2013-01-01

The critically acclaimed serialized review journal for over 50 years, Advances in Geophysics is a highly respected publication in the field of geophysics. Since 1952, each volume has been eagerly awaited, frequently consulted, and praised by researchers and reviewers alike. Now in its 54th volume, it contains much material still relevant today--truly an essential publication for researchers in all fields of geophysics.Key features: * Contributions from leading authorities * Informs and updates on all the latest developments in the field

Clinical characteristics in normal healthy adults with microbleeds on echo-planar gradient-echo T2*-weighted MRI

International Nuclear Information System (INIS)

Takahashi, Wakoh; Ide, Michiru; Ohnuki, Tomohide; Takagi, Shigeharu; Shinohara, Yukito

2004-01-01

The gradient-echo T 2 * -weighted sequence in magnetic resonance imaging is known to be useful for detecting microbleeds (MBs) in patients with intracranial hemorrhage or lacunar stroke. We investigated the characteristics of apparently healthy adults with MBs but without stroke, employing echo-planar gradient-echo T 2 * -weighted MRI. The subjects were recruited from among 3,537 participants who underwent brain check-ups at the HIMEDIC Imaging Center. Of the 3,537 participants, 3,296 (mean age, 55±11 years) without any history of cerebrovascular disease or apparent focal neurological manifestations were selected for the present study. MBs on echo-planar gradient-echo T 2 * -weighted MRI were observed in 74 (2.2%) of the 3,296 subjects. Of a total of 133 lesions found in these 74 persons, 31 were located in the basal ganglia or cortico-subcortical regions. Thirty were in the deep white matter, 19 in the thalamus, 16 in the cerebellum, and 6 in the brain stem. The subjects with MBs were significantly older than the subjects without MBs, and the mean values for their systolic and diastolic blood pressures were higher than those in the subjects without MBs. Asymptomatic cerebral infarction, periventricular hyperintensity, and deep and subcortical white matter hyperintensity on T 1 - and T 2 -weighted MRI were more frequent in the subjects with MBs, as compared with those without MBs. Asymptomatic cerebral infarction, periventricular hyperintensity, and deep and subcortical white matter hyperintensity on T 1 - and T 2 -weighted MRI were more frequent in the subjects with MBs of the basal ganglia or thalamus than in those with MBs in other regions. MBs on echo-planar gradient-echo T 2 * -weighted MRI were thus relatively rare in apparently healthy adults. However, MBs in the basal ganglia or thalamus are suggested to be closely related to intracerebral microangiopathy. Persons with MBs in such regions should therefore be carefully checked for cerebrovascular risk

CUTLASS HF radar observations of high-velocity E-region echoes

Directory of Open Access Journals (Sweden)

M. V. Uspensky

Full Text Available A short event of high-velocity E-region echo observations by the Pykkvibaer HF radar is analysed to study echo parameters and the echo relation to the Farley-Buneman plasma instability. The echoes were detected in several beams aligned closely to the magnetic L-shell direction. Two echo groups were identified: one group corresponded to the classical type 1 echoes with velocities close to the nominal ion-acoustic speed of 400 ms^–1 , while the other group had significantly larger velocities, of the order of 700 ms^–1 . The mutual relationship between the echo power, Doppler velocity, spectral width and elevation angles for these two groups was studied. Plotting of echo parameters versus slant range showed that all ~700 ms^–1 echoes originated from larger heights and distances of 500–700 km, while all ~400 ms^–1 echoes came from lower heights and from farther distances; 700–1000 km. We argue that both observed groups of echoes occurred due to the Farley-Buneman plasma instability excited by strong ( ~70 mVm^–1 and uniformly distributed electric fields. We show that the echo velocities for the two groups were different because the echoes were received from different heights. Such a separation of echo heights occurred due to the differing amounts of ionospheric refraction at short and large ranges. Thus, the ionospheric refraction and related altitude modulation of ionospheric parameters are the most important factors to consider, when various characteristics of E-region decametre irregularities are derived from HF radar measurements.

Key words. Ionosphere (ionospheric irregularities; plasma waves and instabilities; polar ionosphere

Theory and optical design of x-ray echo spectrometers

Science.gov (United States)

Shvyd'ko, Yuri

2017-08-01

X-ray echo spectroscopy, a space-domain counterpart of neutron spin echo, is a recently proposed inelastic x-ray scattering (IXS) technique. X-ray echo spectroscopy relies on imaging IXS spectra and does not require x-ray monochromatization. Due to this, the echo-type IXS spectrometers are broadband, and thus have a potential to simultaneously provide dramatically increased signal strength, reduced measurement times, and higher resolution compared to the traditional narrow-band scanning-type IXS spectrometers. The theory of x-ray echo spectrometers presented earlier [Yu. Shvyd'ko, Phys. Rev. Lett. 116, 080801 (2016), 10.1103/PhysRevLett.116.080801] is developed here further with a focus on questions of practical importance, which could facilitate optical design and assessment of the feasibility and performance of the echo spectrometers. Among others, the following questions are addressed: spectral resolution, refocusing condition, echo spectrometer tolerances, refocusing condition adjustment, effective beam size on the sample, spectral window of imaging and scanning range, impact of the secondary source size on the spectral resolution, angular dispersive optics, focusing and collimating optics, and detector's spatial resolution. Examples of optical designs and characteristics of echo spectrometers with 1-meV and 0.1-meV resolutions are presented.

Echo-Interleaved-Spiral MR Imaging

Energy Technology Data Exchange (ETDEWEB)

Rosenthal, Shirrie; Azhari, Haim [Department of Biomedical Engineering, Technion, Israel Institute of Technology, Haifa 32000 (Israel); Montag, Avram [Elscint Ltd., MRI division, Haifa (Israel)

1999-12-31

Interleaved-Spiral imaging is an efficient method for MRI fast scans. However, images suffer from blurring and artifacts due to field inhomogeneities and the long readout times. In this paper, we combine interleaved-spirals with spin-echo for 3D scans. The refocusing RF-pulses (echoes) refocus off-resonance spins, thus allowing longer acquisition times per excitation, by limiting inhomogeneity effects. The total number of excitations for a 3D scan is reduced by half. The 3D Fourier transform of an object is divided into pairs of slices, one slice is scanned in an outgoing interleaved-spiral, initiated after a 90 degree pulse has been applied. The second slice is scanned in an ingoing interleaved-spiral, after a 180 degree pulse has been applied, thus reaching the slice origin at the echo time. (authors) 4 refs., 3 figs.

Echo phenomena in a plasma

International Nuclear Information System (INIS)

Pavlenko, V.N.

1983-01-01

The mechanism of echo phenomenon in different plasma media: laboratory and cosmic plasma, metals and semiconductors is analyzed to get a more comprehensive idea on collective processes in a plasma and for practical applications in radiophysics and plasma diagnostics. The echo phenomenon permitted to confirm a reversible nature of the Landau damping, to prove the fact that the information on perturbation is conserved in a plasma (as non-damping oscillations of the distribution function) even after disappearing of the macroscopic field. The dependence of the diffusion coefficient on the velocity is measured, microturbulences in a plasma are investigated. New ways of the plasma wave conversion are suggested, as well as ''lightning'' of super-critical plasma layers and regions of plasma non-transparency. Prospective advantages of using echo for studying the mechanisms of charged particle interaction with the surface bounding a plasma are revealed

Application of electrical geophysics to the release of water resources, case of Ain Leuh (Morocco)

Science.gov (United States)

Zitouni, A.; Boukdir, A.; El Fjiji, H.; Baite, W.; Ekouele Mbaki, V. R.; Ben Said, H.; Echakraoui, Z.; Elissami, A.; El Maslouhi, M. R.

2018-05-01

Being seen needs in increasing waters in our contry for fine domestics, manufactures and agricultural, the prospecting of subterranean waters by geologic and hydrogeologic classic method remains inaplicable in the cases of the regions where one does not arrange drillings or polls (soundings) of gratitude (recongnition) in very sufficient (self-important) number. In that case of figure, the method of prospecting geophysics such as the method of nuclear magnetic resonance (NMR) and the method of the geophysics radar are usually used most usually because they showed, worldwide, results very desive in the projects of prospecting and evaluation of the resources in subterranean waters. In the present work, which concerns only the methodology of the electric resistivity, we treat the adopted methodological approach and the study of the case of application in the tray of Ajdir Ain Leuh.

Depth study of insular shelf electric sounding in the Puntas de Abrojal anomaly[Study of Uranium geochemical prospection in Uruguay]; Estudio de la profundidad del zocalo por sondeos electricos en la Anomalia Puntas de Abrojal

Energy Technology Data Exchange (ETDEWEB)

Cicalese, H

1983-07-01

In the framework of the Uranium prospecting Programme, a geophysics team composed by BRGM and DINAMIGE workers were carried out an study about of insular shelf electric sounding on the Puntas de Abrojal area.A geographical location, geologic framework, geophysical survey and methods, materials and results were given.

Geophysical Investigations of Hypersaline Subglacial Water Systems in the Canadian Arctic: A Planetary Analog

Science.gov (United States)

Rutishauser, A.; Sharp, M. J.; Blankenship, D. D.; Skidmore, M. L.; Grima, C.; Schroeder, D. M.; Greenbaum, J. S.; Dowdeswell, J. A.; Young, D. A.

2017-12-01

Robotic exploration and remote sensing of the solar system have identified the presence of liquid water beneath ice on several planetary bodies, with evidence for elevated salinity in certain cases. Subglacial water systems beneath Earth's glaciers and ice sheets may provide terrestrial analogs for microbial habitats in such extreme environments, especially those with higher salinity. Geological data suggest that several ice caps and glaciers in the eastern Canadian High Arctic are partially underlain by evaporite-rich sedimentary rocks, and subglacial weathering of these rocks is potentially conducive to the formation of hypersaline subglacial waters. Here, we combine airborne geophysical data with geological constraints to identify and characterize hypersaline subglacial water systems beneath ice caps in Canada's Queen Elizabeth Islands. High relative bedrock reflectivity and specularity anomalies that are apparent in radio-echo sounding data indicate multiple locations where subglacial water is present in areas where modeled ice temperatures at the glacier bed are well below the pressure melting point. This suggests that these water systems are hypersaline, with solute concentrations that significantly depress the freezing point of water. From combined interpretations of geological and airborne-magnetic data, we define the geological context within which these systems have developed, and identify possible solute-sources for the inferred brine-rich water systems. We also derive subglacial hydraulic potential gradients using airborne laser altimetry and ice thickness data, and apply water routing models to derive subglacial drainage pathways. These allow us to identify marine-terminating glaciers where outflow of the brine-rich waters may be anticipated. These hypersaline subglacial water systems beneath Canadian Arctic ice caps and glaciers may represent robust microbial habitats, and potential analogs for brines that may exist beneath ice masses on planetary

Meteor head echoes - observations and models

Directory of Open Access Journals (Sweden)

A. Pellinen-Wannberg

2005-01-01

Full Text Available Meteor head echoes - instantaneous echoes moving with the velocities of the meteors - have been recorded since 1947. Despite many attempts, this phenomenon did not receive a comprehensive theory for over 4 decades. The High Power and Large Aperture (HPLA features, combined with present signal processing and data storage capabilities of incoherent scatter radars, may give an explanation for the old riddle. The meteoroid passage through the radar beam can be followed with simultaneous spatial-time resolution of about 100m-ms class. The current views of the meteor head echo process will be presented and discussed. These will be related to various EISCAT observations, such as dual-frequency target sizes, altitude distributions and vector velocities.

Characteristics of spondylotic myelopathy on 3D driven-equilibrium fast spin echo and 2D fast spin echo magnetic resonance imaging: a retrospective cross-sectional study.

Science.gov (United States)

Abdulhadi, Mike A; Perno, Joseph R; Melhem, Elias R; Nucifora, Paolo G P

2014-01-01

In patients with spinal stenosis, magnetic resonance imaging of the cervical spine can be improved by using 3D driven-equilibrium fast spin echo sequences to provide a high-resolution assessment of osseous and ligamentous structures. However, it is not yet clear whether 3D driven-equilibrium fast spin echo sequences adequately evaluate the spinal cord itself. As a result, they are generally supplemented by additional 2D fast spin echo sequences, adding time to the examination and potential discomfort to the patient. Here we investigate the hypothesis that in patients with spinal stenosis and spondylotic myelopathy, 3D driven-equilibrium fast spin echo sequences can characterize cord lesions equally well as 2D fast spin echo sequences. We performed a retrospective analysis of 30 adult patients with spondylotic myelopathy who had been examined with both 3D driven-equilibrium fast spin echo sequences and 2D fast spin echo sequences at the same scanning session. The two sequences were inspected separately for each patient, and visible cord lesions were manually traced. We found no significant differences between 3D driven-equilibrium fast spin echo and 2D fast spin echo sequences in the mean number, mean area, or mean transverse dimensions of spondylotic cord lesions. Nevertheless, the mean contrast-to-noise ratio of cord lesions was decreased on 3D driven-equilibrium fast spin echo sequences compared to 2D fast spin echo sequences. These findings suggest that 3D driven-equilibrium fast spin echo sequences do not need supplemental 2D fast spin echo sequences for the diagnosis of spondylotic myelopathy, but they may be less well suited for quantitative signal measurements in the spinal cord.

ECHO Data Partners Join Forces to Federate Access to Resources

Science.gov (United States)

Kendall, J.; Macie, M.

2003-12-01

During the past year the NASA's Earth Science Data and Information System (ESDIS) project has been collaborating with various Earth science data and client providers to design and implement the EOS Clearinghouse (ECHO). ECHO is an open, interoperable metadata clearinghouse and order broker system. ECHO functions as a repository of information intended to streamline access to digital data and services provided by NASA's Earth Science Enterprise and the extended Earth science community. In a unique partnership, ECHO data providers are working to extend their services in the digital era, to reflect current trends in scientific and educational communications. The multi-organization, inter-disciplinary content of ECHO provides a valuable new service to a growing number of Earth science applications and interdisciplinary research efforts. As such, ECHO is expected to attract a wide audience. In this poster, we highlight the contributions of current ECHO data partners and provide information for prospective data partners on how the project supports the incorporation of new collections and effective long-term asset management that is directly under the control of the organizations who contribute resources to ECHO.

Echolocating bats emit a highly directional sonar sound beam in the field

DEFF Research Database (Denmark)

Surlykke, Annemarie; Boel Pedersen, Simon; Jakobsen, Lasse

2009-01-01

Bats use echolocation or biosonar to navigate and find prey at night. They emit short ultrasonic calls and listen for reflected echoes. The beam width of the calls is central to the function of the sonar, but directionality of echolocation calls has never been measured from bats flying in the wild....... We used a microphone array to record sounds and determine horizontal directionality for echolocation calls of the trawling Daubenton's bat, Myotis daubentonii, flying over a pond in its natural habitat. Myotis daubentonii emitted highly directional calls in the field. Directionality increased...... and directionality can be explained by the simple piston model. The model also suggests that the increase in the emitted intensity in the field is caused by the increased directionality, focusing sound energy in the forward direction. The bat may increase directionality by opening the mouth wider to emit a louder...

Ultrafast bold fMRI using single-shot spin-echo echo planar imaging

Directory of Open Access Journals (Sweden)

Boujraf Said

2009-01-01

Full Text Available The choice of imaging parameters for functional MRI can have an impact on the accuracy of functional localization by affecting the image quality and the degree of blood oxygenation-dependent (BOLD contrast achieved. By improving sampling efficiency, parallel acquisition techniques such as sensitivity encoding (SENSE have been used to shorten readout trains in single-shot (SS echo planar imaging (EPI. This has been applied to susceptibility artifact reduction and improving spatial resolution. SENSE together with single-shot spin-echo (SS-SE imaging may also reduce off-resonance artifacts. The goal of this work was to investigate the BOLD response of a SENSE-adapted SE-EPI on a three Tesla scanner. Whole-brain fMRI studies of seven healthy right hand-dominant volunteers were carried out in a three Tesla scanner. fMRI was performed using an SS-SE EPI sequence with SENSE. The data was processed using statistical parametric mapping. Both, group and individual subject data analyses were performed. Individual average percentage and maximal percentage signal changes attributed to the BOLD effect in M1 were calculated for all the subjects as a function of echo time. Corresponding activation maps and the sizes of the activated clusters were also calculated. Our results show that susceptibility artifacts were reduced with the use of SENSE; and the acquired BOLD images were free of the typical quadrature artifacts of SS-EPI. Such measures are crucial at high field strengths. SS SE-EPI with SENSE offers further benefits in this regard and is more specific for oxygenation changes in the microvasculature bed. Functional brain activity can be investigated with the help of single-shot spin echo EPI using SENSE at high magnetic fields.

``Hiss, clicks and pops'' - The enigmatic sounds of meteors

Science.gov (United States)

Finnegan, J. A.

2015-04-01

The improbability of sounds heard simultaneously with meteors allows the phenomenon to remain on the margins of scientific interest and research. This is unjustified, since these audibly perceived electric field effects indicate complex, inconsistent and still unresolved electric-magnetic coupling and charge dynamics; interacting between the meteor; the ionosphere and mesosphere; stratosphere; troposphere and the surface of the earth. This paper reviews meteor acoustic effects, presents illustrating reports and hypotheses and includes a summary of similar and additional phenomena observed during the 2013 February 15 asteroid fragment disintegration above the Russian district of Chelyabinsk. An augmenting theory involving near ground, non uniform electric field production of Ozone, as a stimulated geo-physical phenomenon to explain some hissing `meteor sounds' is suggested in section 2.2. Unlike previous theories, electric-magnetic field fluctuation rates are not required to occur in the audio frequency range for this process to acoustically emit hissing and intermittent impulsive sounds; removing the requirements of direct conversion, passive human transduction or excited, localised acoustic `emitters'. Links to the Armagh Observatory All-sky meteor cameras, electrophonic meteor research and full construction plans for an extremely low frequency (ELF) receiver are also included.

Sound and sound sources

DEFF Research Database (Denmark)

Larsen, Ole Næsbye; Wahlberg, Magnus

2017-01-01

There is no difference in principle between the infrasonic and ultrasonic sounds, which are inaudible to humans (or other animals) and the sounds that we can hear. In all cases, sound is a wave of pressure and particle oscillations propagating through an elastic medium, such as air. This chapter...... is about the physical laws that govern how animals produce sound signals and how physical principles determine the signals’ frequency content and sound level, the nature of the sound field (sound pressure versus particle vibrations) as well as directional properties of the emitted signal. Many...... of these properties are dictated by simple physical relationships between the size of the sound emitter and the wavelength of emitted sound. The wavelengths of the signals need to be sufficiently short in relation to the size of the emitter to allow for the efficient production of propagating sound pressure waves...

An application of the geophysical methods and ALS DTM for the identification of the geological structure in the Kraśnik region - Lublin Upland, Poland

Science.gov (United States)

Kamiński, Mirosław

2017-11-01

The purpose of the study was the assessment of the viability of selected geophysical methods and the Airborne Laser Scanning (ALS) for the identification and interpretation of the geological structure. The studied area is covered with a dense forest. For this reason, the ALS numerical terrain model was applied for the analysis of the topography. Three geophysical methods were used: gravimetric, in the form of a semi-detailed gravimetric photograph, Vertical Electrical Sounding (VES), and Electrical Resistivity Tomography (ERT). The numerical terrain model enabled the identification of Jurassic limestone outcrops and interpretation of the directions of the faults network. The geological interpretation of the digitally processed gravimetric data enabled the determination of the spatial orientation of the synclines and anticlines axes and of the course directions of main faults. Vertical Electrical Sounding carried along the section line perpendicular to the Gościeradów anticline axis enabled the interpretation of the lithology of this structure and identification of its complex tectonic structure. The shallow geophysical surveys using the ERT method enabled the estimation of the thickness of Quaternary formations deposited unconformably on the highly eroded Jurassic limestone outcrop. The lithology of Quaternary, Cretaceous and Jurassic rocks was also interpreted.

A "continuity-index" for assessing ice-sheet dynamics from radar-sounded internal layers

DEFF Research Database (Denmark)

Karlsson, Nanna Bjørnholt; Rippin, David; Bingham, Robert G.

2012-01-01

Radio-echo sounding (RES) of polar icesheets reveals extensive internal layering. The degree of continuity of internal layering holds critical information about the ice-flow field, but previous analyses of this parameter have been limited to qualitative classifications. Here we present a new...... further support that the main trunk and tributaries are unlikely to have undergone substantial migration since the deposition of the internal layering. Significantly, our new method for analyzing internallayers is readily transferable across RES datasets, offering promise for data-led assessments of past...

Comparison between two.magnetic resonance sequences (spin-echo and gradient-echo) in the analysis of lesions of the knee joint meniscus

International Nuclear Information System (INIS)

Marti-Bonati, L.; Casillas, C.

1999-01-01

To compare the diagnostic reliability, the proportion of common diagnoses and the degree of agreement between the results of two magnetic resonance (MR) sequences in the diagnosis of lesions of the meniscus of the knee. One hundred consecutive patients were studied prospectively by MR (1,5 Teslas). All of them underwent T1-weighted spin-echo and T1 and T2-weighted gradient-echo sequences. The final diagnosis was based on the combined results of four imaging sequences. The sensitivity, specificity, positive predictive value (PPV) and negative predictive (NPV) in terms of the final diagnosis were calculated for each meniscus and MR technique. The chi.squared test and kappa test were employed for the statistical analysis. There were discrepancies between the final diagnosis and the spin-echo sequence in 4 cases and between the final diagnosis and the gradient-echo sequences in 5 Both spin-echo and gradient-echo sequences showed the same diagnostic reliabilities: sensitivity of 0.98, specificity of 0.99, PPV of 0.98 and NPV of 0.99. The correlation between the two sequences was highly significant (chi-squared, p < 0.001) with a very high rate of agreement (kappa=0.84). The two sequences can be considered equally reliable in the study of meniscal lesions. (Author) 7 refs

3D modelling of the electromagnetic response of geophysical targets using the FDTD method

Energy Technology Data Exchange (ETDEWEB)

Debroux, P.S. [Univ. of Arizona, Tucson, AZ (United States). Mining and Geological Engineering Dept.

1996-05-01

A publicly available and maintained electromagnetic finite-difference time domain (FDTD) code has been applied to the forward modelling of the response of 1D, 2D and 3D geophysical targets to a vertical magnetic dipole excitation. The FDTD method is used to analyze target responses in the 1 MHz to 100 MHz range, where either conduction or displacement currents may have the controlling role. The response of the geophysical target to the excitation is presented as changes in the magnetic field ellipticity. The results of the FDTD code compare favorably with previously published integral equation solutions of the response of 1D targets, and FDTD models calculated with different finite-difference cell sizes are compared to find the effect of model discretization on the solution. The discretization errors, calculated as absolute error in ellipticity, are presented for the different ground geometry models considered, and are, for the most part, below 10% of the integral equation solutions. Finally, the FDTD code is used to calculate the magnetic ellipticity response of a 2D survey and a 3D sounding of complicated geophysical targets. The response of these 2D and 3D targets are too complicated to be verified with integral equation solutions, but show the proper low- and high-frequency responses.

Diagnosis of partial and complete rotator cuff tears using combined gradient echo and spin echo imaging

International Nuclear Information System (INIS)

Tuite, M.J.; Yandow, D.R.; DeSmet, A.A.; Orwin, J.F.; Quintana, F.A.

1994-01-01

Most magnetic resonance (MR) studies evaluating the rotator cuff for tears have used T2-weighted imaging in the coronal oblique and sagittal oblique planes. T2 * -weighted gradient echo imaging, however, has advantages over spin echo imaging, including contiguous slices without cross-talk, high contrast around the cuff, and intrinsically shorter imaging times which can be used to increase the number of signals averaged and thus improve the signal-to-noise ratio. We reviewed the shoulder MR scans of 87 consecutive patients who underwent both a MR scan and a shoulder arthroscopy during which the size of tears, if present, was graded. The reviewers were blinded as to the history and arthroscopic results. The MR scans included oblique coronal T2 * -weighted gradient echo and oblique sagittal T2-weighted spin echo images. MR cuff grades were correlated with arthroscopic findings. For complete tears, the sensitivity of MR was 0.91 and the specificity 0.95. For partial tears, the sensitivity was 0.74 and the specificity 0.87. This accuracy is similar to two-plane T2-weighted imaging as previously reported in the literature. There was a statistically significant correlation (p < 0.0005) between the cuff grade as determined by MR and the arthroscopic findings. (orig.)

Diagnosis of partial and complete rotator cuff tears using combined gradient echo and spin echo imaging

Energy Technology Data Exchange (ETDEWEB)

Tuite, M J [Dept. of Radiology, Univ. of Wisconsin, Madison, WI (United States); Yandow, D R [Dept. of Radiology, Univ. of Wisconsin, Madison, WI (United States); DeSmet, A A [Dept. of Radiology, Univ. of Wisconsin, Madison, WI (United States); Orwin, J F [Div. of Orthopedic Surgery, Univ. of Wisconsin, Madison, WI (United States); Quintana, F A [Dept. of Biostatistics, Univ. of Wisconsin, Madison, WI (United States)

1994-10-01

Most magnetic resonance (MR) studies evaluating the rotator cuff for tears have used T2-weighted imaging in the coronal oblique and sagittal oblique planes. T2{sup *}-weighted gradient echo imaging, however, has advantages over spin echo imaging, including contiguous slices without cross-talk, high contrast around the cuff, and intrinsically shorter imaging times which can be used to increase the number of signals averaged and thus improve the signal-to-noise ratio. We reviewed the shoulder MR scans of 87 consecutive patients who underwent both a MR scan and a shoulder arthroscopy during which the size of tears, if present, was graded. The reviewers were blinded as to the history and arthroscopic results. The MR scans included oblique coronal T2{sup *}-weighted gradient echo and oblique sagittal T2-weighted spin echo images. MR cuff grades were correlated with arthroscopic findings. For complete tears, the sensitivity of MR was 0.91 and the specificity 0.95. For partial tears, the sensitivity was 0.74 and the specificity 0.87. This accuracy is similar to two-plane T2-weighted imaging as previously reported in the literature. There was a statistically significant correlation (p < 0.0005) between the cuff grade as determined by MR and the arthroscopic findings. (orig.)

Utility of dual echo T2-weighted turbo spin echo MR imaging for differentiation of solid, malignant hepatic lesions from nonsolid, benign hepatic lesions

International Nuclear Information System (INIS)

Yang, Dal Mo; Yoon, Myung Hwan; Kim, Hak Soo; Lee, Eun Joo; Kim, Jong Ho; Kim, Hyung Sik; Chung, Jin Woo

1999-01-01

To evaluate the additive value of multiphasic contrast-enhanced dynamic MR imaging as a supplement to dual-echo T2-weighted TSE MR imaging for the differentiation of solid, malignant hepatic lesions from nonsolid, benign hepatic lesions. Two radiologists retrospectively reviewed dual-echo T2-weighted TSE MR images and gadolinium-enhanced MR images in 51 patients with hepatic lesions (28 malignant, 69 benign). For the differentiation of malignant from benign lesions, as seen on dual-echo T2-weighted TSE MR images, we evaluated sensitivity, specificity, and accuracy, and compared with the results with those for dual echo T2-weighted MR images plus multiphasic contrast-enhanced dynamic MR images. In addition, Az values for dual echo T2-weighted MR images were compared with those for dual echo T2-weighted MR images plus multiphasic contrast-enhanced dynamic MR images. For the differentiation of malignant from benign hepatic lesions, as seen on dual-echo T2-weighted TSE images, sensitivity, specificity, and accuracy were 80.0%, 97.5%, and 93.9%, respectively, for lesions less than 3cm in diameter, and 92.3%, 95.0%, and 93.5%, respectively, for those that were 3cm or larger. The results for dual-echo T2-weighted MR imaging plus multiphasic contrast-enhanced dynamic MR imaging were 86.7%, 100.0%, and 97.3%, respectively, for lesions less than 3cm, and 92.3%, 100.0%, and 95.7%, respectively for those that were 3cm or larger. There were no significant differences in sensitivity, specificity, or accuracy between the results obtained using dual-echo T2-weighted MR imaging and those obtained with dual-echo T2-weighted MR imaging plus multiphasic contrast-enhanced dynamic MR imaging. Nor were these statistically significant differences in Az values between the two groups. For the differentiation of solid, malignant hepatic lesions from nonsolid, benign hepatic lesions, there is no difference in accuracy between dual-echo T2-weighted TSE MR imaging and the additional use of

Comparison of gradient-recalled echo and spin-echo echo-planar imaging MR elastography in staging liver fibrosis. A meta-analysis

International Nuclear Information System (INIS)

Kim, Yong Seek; Jang, Yu Na; Song, Ji Soo

2018-01-01

To compare the diagnostic performance of gradient-recalled echo-based magnetic resonance elastography (GRE-MRE) and spin-echo echo-planar imaging-based MRE (SE-EPI-MRE) in liver fibrosis staging. A systematic literature search was performed to identify studies involving the performance of MRE for the diagnosis of liver fibrosis. Pooled sensitivity, specificity, positive and negative likelihood ratios, the diagnostic odds ratio, and a summary receiver operating characteristic (ROC) curve were estimated by using a bivariate random effects model. Subgroup analyses were performed between different study characteristics. Twenty-six studies with a total of 3,200 patients were included in the meta-analysis. Pooled sensitivity and specificity of GRE-MRE and SE-EPI-MRE did not differ significantly. The area under the summary ROC curve for stage diagnosis of any (F ≥ 1), significant (F ≥ 2), advanced (F ≥ 3), and cirrhosis (F = 4) on GRE-MRE and SE-EPI-MRE were 0.93 versus 0.94, 0.95 versus 0.94, 0.94 versus 0.95, and 0.92 versus 0.93, respectively. Substantial heterogeneity was detected for both sequences. Both GRE and SE-EPI-MRE show high sensitivity and specificity for detection of each stage of liver fibrosis, without significant differences. Magnetic resonance elastography (MRE) may be useful for noninvasive evaluation of liver fibrosis in chronic liver disease. (orig.)

Theoretical determination of transit time locus curves for ultrasonic pulse echo testing - ALOK. Pt. 4

International Nuclear Information System (INIS)

Grohs, B.

1983-01-01

The ALOK-technique allows the simultaneous detection of flaws and their evaluation with respect to type, location and dimension by interpretation of the transit time behaviour during scanning of the reflector. The accuracy of information obtained by means of this technique can be further improved both during interference elimination and reconstruction owing to the ability of exact calculation of possible transit time locus curves of given reflectors. The mathematical solution of transit time locus curve calculations refers here to pulse echo testing in consideration of the refraction of sound on the forward wedge/test object - interface. The method of solving the problem is equivalent to the Fermat's principle in optics. (orig.) [de

An application of the geophysical methods and ALS DTM for the identification of the geological structure in the Kraśnik region – Lublin Upland, Poland

Directory of Open Access Journals (Sweden)

Kamiński Mirosław

2017-01-01

Full Text Available The purpose of the study was the assessment of the viability of selected geophysical methods and the Airborne Laser Scanning (ALS for the identification and interpretation of the geological structure. The studied area is covered with a dense forest. For this reason, the ALS numerical terrain model was applied for the analysis of the topography. Three geophysical methods were used: gravimetric, in the form of a semi-detailed gravimetric photograph, Vertical Electrical Sounding (VES, and Electrical Resistivity Tomography (ERT. The numerical terrain model enabled the identification of Jurassic limestone outcrops and interpretation of the directions of the faults network. The geological interpretation of the digitally processed gravimetric data enabled the determination of the spatial orientation of the synclines and anticlines axes and of the course directions of main faults. Vertical Electrical Sounding carried along the section line perpendicular to the Gościeradów anticline axis enabled the interpretation of the lithology of this structure and identification of its complex tectonic structure. The shallow geophysical surveys using the ERT method enabled the estimation of the thickness of Quaternary formations deposited unconformably on the highly eroded Jurassic limestone outcrop. The lithology of Quaternary, Cretaceous and Jurassic rocks was also interpreted.

Revival of silenced echo and quantum memory for light

Energy Technology Data Exchange (ETDEWEB)

Damon, V; Bonarota, M; Louchet-Chauvet, A; Chaneliere, T; Le Gouet, J-L, E-mail: jean-louis.legouet@lac.u-psud.fr [Laboratoire Aime Cotton, CNRS-UPR 3321, Univ. Paris-Sud, Bat. 505, 91405 Orsay cedex (France)

2011-09-15

We propose an original quantum memory protocol. It belongs to the class of rephasing processes and is closely related to two-pulse photon echo. It is known that the strong population inversion produced by the rephasing pulse prevents the plain two-pulse photon echo from serving as a quantum memory scheme. Indeed, gain and spontaneous emission generate prohibitive noise. A second {pi}-pulse can be used to simultaneously reverse the atomic phase and bring the atoms back into the ground state. Then a secondary echo is radiated from a non-inverted medium, avoiding contamination by gain and spontaneous emission noise. However, one must kill the primary echo, in order to preserve all the information for the secondary signal. In the present work, spatial phase mismatching is used to silence the standard two-pulse echo. An experimental demonstration is presented.

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Duel frequency echo data acquisition system for sea-floor classification

Digital Repository Service at National Institute of Oceanography (India)

Navelkar, G.S.; Desai, R.G.P.; Chakraborty, B.

An echo data acquisition system is designed to digitize echo signal from a single beam shipboard echo-sounder for use in sea-floor classification studies using a 12 bit analog to digital (A/D) card with a maximum sampling frequency of 1 MHz. Both 33...

Variations in the occurrence of SuperDARN F region echoes

Directory of Open Access Journals (Sweden)

M. Ghezelbash

2014-02-01

Full Text Available The occurrence of F region ionospheric echoes observed by a number of SuperDARN HF radars is analyzed statistically in order to infer solar cycle, seasonal, and diurnal trends. The major focus is on Saskatoon radar data for 1994–2012. The distribution of the echo occurrence rate is presented in terms of month of observation and magnetic local time. Clear repetitive patterns are identified during periods of solar maximum and solar minimum. For years near solar maximum, echoes are most frequent near midnight during winter. For years near solar minimum, echoes occur more frequently near noon during winter, near dusk and dawn during equinoxes and near midnight during summer. Similar features are identified for the Hankasalmi and Prince George radars in the northern hemisphere and the Bruny Island TIGER radar in the southern hemisphere. Echo occurrence for the entire SuperDARN network demonstrates patterns similar to patterns in the echo occurrence for the Saskatoon radar and for other radars considered individually. In terms of the solar cycle, the occurrence rate of nightside echoes is shown to increase by a factor of at least 3 toward solar maximum while occurrence of the near-noon echoes does not significantly change with the exception of a clear depression during the declining phase of the solar cycle.

Sound velocity from inverted echo sounders (IES) in the western Pacific Ocean from 1992-08-26 to 1993-03-22 (NODC Accession 9300159)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains inverted echo sounder data collected from two stations in the western Pacific, TPW nominally @ 2S and 154E and TPE nominally @ 2S and 164E....

Fast spin echo MRI techniques. Contrast characteristics and clinical potential. Techniques d'IRM en fast spin echo. Caracteristiques de contraste et potentiels cliniques

Energy Technology Data Exchange (ETDEWEB)

Melki, P.; Mulkern, R.V.; Dacher, J.N.; Helenon, O.; Higuchi, N. (Harvard Medical School, Boston, MA (United States)); Oshio, K.; Jolesz, F. (Keio Univ., Tokyo (Japan)); Pourcelot, L. (Hopital Bretonneau, 37 - Tours (France)); Einstein, S. (General Electric Medical System, Milwaukee, WI (United States))

1993-03-01

Based on partial RF echo planar principles, Fast Spin Echo techniques (FSE) were implemented on high field systems. These methods produce image quality and contrast which resemble to conventional spin echo (SE) techniques. By reducing acquisition times by factors between 1.4 and 16 over SE methods, FSE allows for several imaging options usually prohibitive with conventional spin echo (SE) sequences. These include fast scans (especially breathold acquisitions); improved T2 contrast with longer TR intervals; increased spatial resolution with the use of larger image matrices and/or smaller fields of view; and 3D volume imaging with a 3D multislab FSE technique. Contrast features of FSE techniques are directly comparable to those of multiple echo SE sequences using the same echo spacing than FSE methods. However, essential contrast differences existing between the FSE sequences and their routine asymmetric dual SE counterpart can be identified. Decreased magnetic susceptibility effects and increased fat signal present within T2 weighted images compared to conventional dual SE images are due to the use of shorter echo spacings employed in FSE sequences. Off-resonance irradiation inherent to the use of a large number of radio frequency pulses in shown to results in dramatic magnetization contrast transfer effects in FSE images acquired in multislice mode.

Definition of a critical confining zone using surface geophysical methods

International Nuclear Information System (INIS)

Eddy-Dilek, C.A.; Looney, B.B.; Hoekstra, P.; Harthill, N.; Blohm, M.; Phillips, D.R.

1997-01-01

Definition of the hydrologic framework in layered sediments of fluvial and deltaic origin is a difficult challenge for environmental characterization and remediation programs due to the lithologic and stratigraphic heterogeneities inherent in these settings. The authors set out to use complementary geophysical surveys to determine the nature and extent of a deep confining unit at the Savannah River Site, South Carolina. Time Domain Electromagnetic (TDEM) soundings were used to define the electrical conductance of the clayey confining unit (aquitard), and shear-wave reflection seismic was used to define the stratigraphic framework. Based on correlations with borehole geophysical logs and sieve data, the shear-wave seismic proved capable of defining relatively fine layering in the coastal plain sediments, the upper and lower surfaces of a critical confining unit, and erosional features on the surface of the confining unit. The TDEM surveys defined the presence or absence of the clay facies of the confining unit. Moreover, by constraining the interpretation of the TDEM data with the thickness of the confining unit derived from the seismic data, the authors mapped the extent of the unit, showing where the clay is thicker, where it probably was never deposited, and where it was eroded by downcutting channels. These results have significant implications on the design and optimization of remedial systems

Design and Control of a New Biomimetic Transfemoral Knee Prosthesis Using an Echo-Control Scheme

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Mario G. Bernal-Torres

2018-01-01

Full Text Available Passive knee prostheses require a significant amount of additional metabolic energy to carry out a gait cycle, therefore affecting the natural human walk performance. Current active knee prostheses are still limited because they do not reply with accuracy of the natural human knee movement, and the time response is relatively large. This paper presents the design and control of a new biomimetic-controlled transfemoral knee prosthesis based on a polycentric-type mechanism. The aim was to develop a knee prosthesis able to provide additional power and to mimic with accuracy of the natural human knee movement using a stable control strategy. The design of the knee mechanism was obtained from the body-guidance kinematics synthesis based on real human walking patterns obtained from computer vision and 3D reconstruction. A biomechanical evaluation of the synthesized prosthesis was then carried out. For the activation and control of the prosthesis, an echo-control strategy was proposed and developed. In this echo-control strategy, the sound side leg is sensed and synchronized with the activation of the knee prosthesis. An experimental prototype was built and evaluated in a test rig. The results revealed that the prosthetic knee is able to mimic the biomechanics of the human knee.

Ultrasound pulse-echo measurements on rough surfaces with linear array transducers

DEFF Research Database (Denmark)

Sjøj, Sidsel M. N.; Blanco, Esther N.; Wilhjelm, Jens E.

2012-01-01

The echo from planar surfaces with rms roughness, Rq, in the range from 0-155 μm was measured with a clinical linear array transducer at different angles of incidence at 6 MHz and 12 MHz. The echo-pulse from the surfaces was isolated with an equal sized window and the power of the echo-pulse was ......The echo from planar surfaces with rms roughness, Rq, in the range from 0-155 μm was measured with a clinical linear array transducer at different angles of incidence at 6 MHz and 12 MHz. The echo-pulse from the surfaces was isolated with an equal sized window and the power of the echo......-pulse was calculated. The power of the echo from the smooth surface (Rq = 0) is highly angle-dependent due to a high degree of specular reflection. Within the angular range considered here, -10° to 10°, the variation spans a range of 18 dB at both 6 MHz and 12 MHz. When roughness increases, the angle......-dependence decreases, as the echo process gradually changes from pure reflection to being predominantly governed by backscattering. The power of the echoes from the two roughest surfaces (Rq = 115 μm and 155 μm) are largely independent of angle at both 6 MHz and 12 MHz with a variation of 2 dB in the angular range...

The architecture of dynamic reservoir in the echo state network

Science.gov (United States)

Cui, Hongyan; Liu, Xiang; Li, Lixiang

2012-09-01

Echo state network (ESN) has recently attracted increasing interests because of its superior capability in modeling nonlinear dynamic systems. In the conventional echo state network model, its dynamic reservoir (DR) has a random and sparse topology, which is far from the real biological neural networks from both structural and functional perspectives. We hereby propose three novel types of echo state networks with new dynamic reservoir topologies based on complex network theory, i.e., with a small-world topology, a scale-free topology, and a mixture of small-world and scale-free topologies, respectively. We then analyze the relationship between the dynamic reservoir structure and its prediction capability. We utilize two commonly used time series to evaluate the prediction performance of the three proposed echo state networks and compare them to the conventional model. We also use independent and identically distributed time series to analyze the short-term memory and prediction precision of these echo state networks. Furthermore, we study the ratio of scale-free topology and the small-world topology in the mixed-topology network, and examine its influence on the performance of the echo state networks. Our simulation results show that the proposed echo state network models have better prediction capabilities, a wider spectral radius, but retain almost the same short-term memory capacity as compared to the conventional echo state network model. We also find that the smaller the ratio of the scale-free topology over the small-world topology, the better the memory capacities.

Electric Dipole Echoes in Rydberg Atoms

International Nuclear Information System (INIS)

Yoshida, S.; Reinhold, C. O.; Burgdoerfer, J.; Zhao, W.; Mestayer, J. J.; Lancaster, J. C.; Dunning, F. B.

2007-01-01

We report the first observation of echoes in the electric dipole moment of an ensemble of Rydberg atoms precessing in an external electric field F. Rapid reversal of the field direction is shown to play a role similar to that of a π pulse in NMR in rephasing a dephased ensemble of electric dipoles resulting in the buildup of an echo. The mechanisms responsible for this are discussed with the aid of classical trajectory Monte Carlo simulations

No counterpart of visual perceptual echoes in the auditory system.

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Barkın İlhan

Full Text Available It has been previously demonstrated by our group that a visual stimulus made of dynamically changing luminance evokes an echo or reverberation at ~10 Hz, lasting up to a second. In this study we aimed to reveal whether similar echoes also exist in the auditory modality. A dynamically changing auditory stimulus equivalent to the visual stimulus was designed and employed in two separate series of experiments, and the presence of reverberations was analyzed based on reverse correlations between stimulus sequences and EEG epochs. The first experiment directly compared visual and auditory stimuli: while previous findings of ~10 Hz visual echoes were verified, no similar echo was found in the auditory modality regardless of frequency. In the second experiment, we tested if auditory sequences would influence the visual echoes when they were congruent or incongruent with the visual sequences. However, the results in that case similarly did not reveal any auditory echoes, nor any change in the characteristics of visual echoes as a function of audio-visual congruence. The negative findings from these experiments suggest that brain oscillations do not equivalently affect early sensory processes in the visual and auditory modalities, and that alpha (8-13 Hz oscillations play a special role in vision.

Fast spin echo MRI techniques. Contrast characteristics and clinical potential

International Nuclear Information System (INIS)

Melki, P.; Mulkern, R.V.; Dacher, J.N.; Helenon, O.; Higuchi, N.; Oshio, K.; Jolesz, F.; Pourcelot, L.; Einstein, S.

1993-01-01

Based on partial RF echo planar principles, Fast Spin Echo techniques (FSE) were implemented on high field systems. These methods produce image quality and contrast which resemble to conventional spin echo (SE) techniques. By reducing acquisition times by factors between 1.4 and 16 over SE methods, FSE allows for several imaging options usually prohibitive with conventional spin echo (SE) sequences. These include fast scans (especially breathold acquisitions); improved T2 contrast with longer TR intervals; increased spatial resolution with the use of larger image matrices and/or smaller fields of view; and 3D volume imaging with a 3D multislab FSE technique. Contrast features of FSE techniques are directly comparable to those of multiple echo SE sequences using the same echo spacing than FSE methods. However, essential contrast differences existing between the FSE sequences and their routine asymmetric dual SE counterpart can be identified. Decreased magnetic susceptibility effects and increased fat signal present within T2 weighted images compared to conventional dual SE images are due to the use of shorter echo spacings employed in FSE sequences. Off-resonance irradiation inherent to the use of a large number of radio frequency pulses in shown to results in dramatic magnetization contrast transfer effects in FSE images acquired in multislice mode

Echo project

DEFF Research Database (Denmark)

Gfader, Verina; Carson, Rebecca; Kraus, Chris

2016-01-01

team to both present the printed matter in the format of running a book stall, and stage a discursive event at the Classroom. Echo reverberates some of the encounters and debates there, with new commissioned chapters propelling a ongoing correspondence across urban environs: An essay on the General...... mothers and demonology (Kathy Acker’s property deals in the UK), and more; and future materials formalized as poster texts . . ....

Whole brain, high resolution multiband spin-echo EPI fMRI at 7 T: A comparison with gradient-echo EPI using a color-word Stroop task

NARCIS (Netherlands)

Boyacioglu, R.; Schulz, J.; Müller, N.C.J.; Koopmans, P.J.; Barth, M.; Norris, David Gordon

2014-01-01

A whole brain, multiband spin-echo (SE) echo planar imaging (EPI) sequence employing a high spatial (1.5 mm isotropic) and temporal (TR of 2 s) resolution was implemented at 7 T. Its overall performance (tSNR, sensitivity and CNR) was assessed and compared to a geometrically matched gradient-echo

Time-resolved echo-shared parallel MRA of the lung: observer preference study of image quality in comparison with non-echo-shared sequences

International Nuclear Information System (INIS)

Fink, C.; Puderbach, M.; Zaporozhan, J.; Plathow, C.; Kauczor, H.-U.; Ley, S.

2005-01-01

The aim of this study was to evaluate the image quality of time-resolved echo-shared parallel MRA of the lung. The pulmonary vasculature of nine patients (seven females, two males; median age: 44 years) with pulmonary disease was examined using a time-resolved MRA sequence combining echo sharing with parallel imaging (time-resolved echo-shared angiography technique, or TREAT). The sharpness of the vessel borders, conspicuousness of peripheral lung vessels, artifact level, and overall image quality of TREAT was assessed independently by four readers in a side-by-side comparison with non-echo-shared time-resolved parallel MRA data (pMRA) previously acquired in the same patients. Furthermore, the SNR of pulmonary arteries (PA) and veins (PV) achieved with both pulse sequences was compared. The mean voxel size of TREAT MRA was decreased by 24% compared with the non-echo-shared MRA. Regarding the sharpness of the vessel borders, conspicuousness of peripheral lung vessels, and overall image quality the TREAT sequence was rated superior in 75-76% of all cases. If the TREAT images were preferred over the pMRA images, the advantage was rated as major in 61-71% of all cases. The level of artifacts was not increased with the TREAT sequence. The mean interobserver agreement for all categories ranged between fair (artifact level) and good (overall image quality). The maximum SNR of TREAT did not differ from non-echo-shared parallel MRA (PA: TREAT: 273±45; pMRA: 280±71; PV: TREAT: 273±33; pMRA: 258±62). TREAT achieves a higher spatial resolution than non-echo-shared parallel MRA which is also perceived as an improved image quality. (orig.)

Effect of echolocation behavior-related constant frequency-frequency modulation sound on the frequency tuning of inferior collicular neurons in Hipposideros armiger.

Science.gov (United States)

Tang, Jia; Fu, Zi-Ying; Wei, Chen-Xue; Chen, Qi-Cai

2015-08-01

In constant frequency-frequency modulation (CF-FM) bats, the CF-FM echolocation signals include both CF and FM components, yet the role of such complex acoustic signals in frequency resolution by bats remains unknown. Using CF and CF-FM echolocation signals as acoustic stimuli, the responses of inferior collicular (IC) neurons of Hipposideros armiger were obtained by extracellular recordings. We tested the effect of preceding CF or CF-FM sounds on the shape of the frequency tuning curves (FTCs) of IC neurons. Results showed that both CF-FM and CF sounds reduced the number of FTCs with tailed lower-frequency-side of IC neurons. However, more IC neurons experienced such conversion after adding CF-FM sound compared with CF sound. We also found that the Q 20 value of the FTC of IC neurons experienced the largest increase with the addition of CF-FM sound. Moreover, only CF-FM sound could cause an increase in the slope of the neurons' FTCs, and such increase occurred mainly in the lower-frequency edge. These results suggested that CF-FM sound could increase the accuracy of frequency analysis of echo and cut-off low-frequency elements from the habitat of bats more than CF sound.

Improved methods for nightside time domain Lunar Electromagnetic Sounding

Science.gov (United States)

Fuqua-Haviland, H.; Poppe, A. R.; Fatemi, S.; Delory, G. T.; De Pater, I.

2017-12-01

Time Domain Electromagnetic (TDEM) Sounding isolates induced magnetic fields to remotely deduce material properties at depth. The first step of performing TDEM Sounding at the Moon is to fully characterize the dynamic plasma environment, and isolate geophysically induced currents from concurrently present plasma currents. The transfer function method requires a two-point measurement: an upstream reference measuring the pristine solar wind, and one downstream near the Moon. This method was last performed during Apollo assuming the induced fields on the nightside of the Moon expand as in an undisturbed vacuum within the wake cavity [1]. Here we present an approach to isolating induction and performing TDEM with any two point magnetometer measurement at or near the surface of the Moon. Our models include a plasma induction model capturing the kinetic plasma environment within the wake cavity around a conducting Moon, and a geophysical forward model capturing induction in a vacuum. The combination of these two models enable the analysis of magnetometer data within the wake cavity. Plasma hybrid models use the upstream plasma conditions and interplanetary magnetic field (IMF) to capture the wake current systems formed around the Moon. The plasma kinetic equations are solved for ion particles with electrons as a charge-neutralizing fluid. These models accurately capture the large scale lunar wake dynamics for a variety of solar wind conditions: ion density, temperature, solar wind velocity, and IMF orientation [2]. Given the 3D orientation variability coupled with the large range of conditions seen within the lunar plasma environment, we characterize the environment one case at a time. The global electromagnetic induction response of the Moon in a vacuum has been solved numerically for a variety of electrical conductivity models using the finite-element method implemented within the COMSOL software. This model solves for the geophysically induced response in vacuum to

Scex 3 and Electron Echo 7, a Comparison of Data from Two Rocket Experiments.

Science.gov (United States)

Bale, Stuart Douglas

Results from two separate active sounding rocket experiments are presented and discussed. The SCEX III sounding rocket (NASA 39.002 UE) and Electron Echo 7 (NASA 36.015) were both launched from the Poker Flat Research Range (65.1^circ N, 147.5^circ W) near Fairbanks, Alaska, on 1 February, 1990 and 9 February, 1988, respectively. Each payload was equipped with an electron accelerator to study both natural and beam-related plasma phenomena. Data from the SCEX III retarding potential analyzer (RPA) and 3805 A and 3914 A photometers show evidence of a plasma discharge process occurring concomitant with operation of the electron gun. This appears as an enhanced electron current, nonlinear with gun injection current, in the RPA. The photometers register a sharp increase in luminosity during full current electron injection. This luminosity is an indicator of the ionizing electron-neutral collisions which liberate electrons and lead to the cascade-type discharge process. These observations are used to attempt to infer the mechanism of electron acceleration which leads to the discharge process. Before the electron gun was activated, the SCEX III payload flew through a region of auroral activity as evidenced by ground-based all-sky TV and energetic particle flux in the forward payload RPA. During this time, low frequency (10 Hz) electrostatic waves were observed in the DC receivers and Langmuir probe instrument. This data is analyzed, with a cross-spectral technique, and an approximate wave number is inferred. Comparison with theory suggests that the observed wave is the electrostatic ion cyclotron mode (EIC) operating on a heavy ion species (NO or O _2). The Echo 7 nose payload, carrying a plasma wave receiver, was ejected upfield of the main electron gun -equipped payload. Data from the swept frequency analyzer experiment provide wave amplitudes, at frequencies up to 15 MHz, as a function of separation of the main and nose payloads. These observations, and the wave modes

ANNALS OF GEOPHYSICS: AD MAJORA

Directory of Open Access Journals (Sweden)

Fabio Florindo

2014-03-01

Full Text Available Annals of Geophysics is a bimonthly international journal, which publishes scientific papers in the field of geophysics sensu lato. It derives from Annali di Geofisica, which commenced publication in January 1948 as a quarterly periodical devoted to general geophysics, seismology, earth magnetism, and atmospheric studies. The journal was published regularly for a quarter of a century until 1982 when it merged with the French journal Annales de Géophysique to become Annales Geophysicae under the aegis of the European Geophysical Society. In 1981, this journal ceased publication of the section on solid earth geophysics, ending the legacy of Annali di Geofisica. In 1993, the Istituto Nazionale di Geofisica (ING, founder of the journal, decided to resume publication of its own journal under the same name, Annali di Geofisica. To ensure continuity, the first volume of the new series was assigned the volume number XXXVI (following the last issue published in 1982. In 2002, with volume XLV, the name of the journal was translated into English to become Annals of Geophysics and in consequence the journal impact factor counter was restarted. Starting in 2010, in order to improve its status and better serve the science community, Annals of Geophysics has instituted a number of editorial changes including full electronic open access, freely accessible online, the possibility to comment on and discuss papers online, and a board of editors representing Asia and the Americas as well as Europe. [...

Ground geophysical study of the Buckeye mine tailings, Boulder watershed, Montana

Science.gov (United States)

McDougal, Robert R.; Smith, Bruce D.

2000-01-01

The Buckeye mine site is located in the Boulder River watershed along Basin Creek, in northern Jefferson County, Montana. This project is part of the Boulder River watershed Abandoned Mine Lands Initiative, and is a collaborative effort between the U.S. Geological Survey and Bureau of Land Management in the U.S. Department of the Interior, and the U.S. Forest Service in the U.S. Department of Agriculture. The site includes a large flotation milltailing deposit, which extends to the stream and meadows below the mine. These tailings contain elevated levels of metals, such as silver, cadmium, copper, lead, and zinc. Metal-rich fluvial tailings containing these metals, are possible sources of ground and surface water contamination. Geophysical methods were used to characterize the sediments at the Buckeye mine site. Ground geophysical surveys, including electromagnetics, DC resistivity, and total field magnetic methods, were used to delineate anomalies that probably correlate with subsurface metal contamination. Subsurface conductivity was mapped using EM-31 and EM-34 terrain conductivity measuring systems. The conductivity maps represent variation of concentration of dissolved solids in the subsurface from a few meters, to an approximate depth of 30 meters. Conductive sulfides several centimeters thick were encountered in a shallow trench, dug in an area of very high conductivity, at a depth of approximately 1 to1.5 meters. Laboratory measurements of samples of the sulfide layers show the conductivity is on the order of 1000 millisiemens. DC resistivity soundings were used to quantify subsurface conductivity variations and to estimate the depth to bedrock. Total field magnetic measurements were used to identify magnetic metals in the subsurface. The EM surveys identified several areas of relatively high conductivity and detected a conductive plume extending to the southwest, toward the stream. This plume correlates well with the potentiometric surface and direction of

The EChO science case

DEFF Research Database (Denmark)

Tinetti, Giovanna; Drossart, Pierre; Eccleston, Paul

2015-01-01

in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary....... The mission can target super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300–3000 K) of F to M-type host stars. The EChO core science would be delivered by a three-tier survey. The EChO Chemical Census: This is a broad survey of a few...

J-NSE: Neutron spin echo spectrometer

Directory of Open Access Journals (Sweden)

Olaf Holderer

2015-08-01

Full Text Available Neutron Spin-Echo (NSE spectroscopy is well known as the only neutron scattering technique that achieves energy resolution of several neV. By using the spin precession of polarized neutrons in magnetic field one can measure tiny velocity changes of the individual neutron during the scattering process. Contrary to other inelastic neutron scattering techniques, NSE measures the intermediate scattering function S(Q,t in reciprocal space and time directly. The Neutron Spin-Echo spectrometer J-NSE, operated by JCNS, Forschungszentrum Jülich at the Heinz Maier-Leibnitz Zentrum (MLZ in Garching, covers a time range (2 ps to 200 ns on length scales accessible by small angle scattering technique. Along with conventional NSE spectroscopy that allows bulk measurements in transmission mode, J-NSE offers a new possibility - gracing incidence spin echo spectroscopy (GINSENS, developed to be used as "push-button" option in order to resolve the depth dependent near surface dynamics.

Echo Shaping Using Sums of Damped Complex Sinusoids

DEFF Research Database (Denmark)

Putnam, Lance Jonathan

2015-01-01

Feedback delay lines are the basis of myriad audio effects and reverberation schemes. The feedback delay line, by itself, is limited to producing an infinite sequence of exponentially decaying echoes. We introduce a new type of linear time-invariant echo effect whose impulse response is a general...

Magnetic resonance, especially spin echo, in spinor Bose-Einstein condensates

International Nuclear Information System (INIS)

Yasunaga, Masashi; Tsubota, Makoto

2009-01-01

Magnetic resonance, especially NMR and ESR, has been studied in magnetic materials for a long time, having been used in various fields. Spin echo is typical phenomenon in magnetic resonance. The magnetic resonance should be applied to spinor Bose-Einstein condensates (BECs). We numerically study spin echo of a spinor BEC in a gradient magnetic field by calculating the spin-1 two-dimensional Gross-Pitaevskii equations, obtaining the recovery of the signal of the spins, which is called spin echo. We will discuss the relation between the spin echo and the Stern-Gelrach separation in the system.

Developments in geophysical exploration methods

CERN Document Server

1982-01-01

One of the themes in current geophysical development is the bringing together of the results of observations made on the surface and those made in the subsurface. Several benefits result from this association. The detailed geological knowledge obtained in the subsurface can be extrapolated for short distances with more confidence when the geologi­ cal detail has been related to well-integrated subsurface and surface geophysical data. This is of value when assessing the characteristics of a partially developed petroleum reservoir. Interpretation of geophysical data is generally improved by the experience of seeing the surface and subsurface geophysical expression of a known geological configuration. On the theoretical side, the understanding of the geophysical processes themselves is furthered by the study of the phenomena in depth. As an example, the study of the progress of seismic wave trains downwards and upwards within the earth has proved most instructive. This set of original papers deals with some of ...

Chaos theory in geophysics: past, present and future

International Nuclear Information System (INIS)

Sivakumar, B.

2004-01-01

The past two decades of research on chaos theory in geophysics has brought about a significant shift in the way we view geophysical phenomena. Research on chaos theory in geophysics continues to grow at a much faster pace, with applications to a wide variety of geophysical phenomena and geophysical problems. In spite of our success in understanding geophysical phenomena also from a different (i.e. chaotic) perspective, there still seems to be lingering suspicions on the scope of chaos theory in geophysics. The goal of this paper is to present a comprehensive account of the achievements and status of chaos theory in geophysics, and to disseminate the hope and scope for the future. A systematic review of chaos theory in geophysics, covering a wide spectrum of geophysical phenomena studied (e.g. rainfall, river flow, sediment transport, temperature, pressure, tree ring series, etc.), is presented to narrate our past achievements not only in understanding and predicting geophysical phenomena but also in improving the chaos identification and prediction techniques. The present state of chaos research in geophysics (in terms of geophysical phenomena, problems, and chaos methods) and potential for future improvements (in terms of where, why and possibly how) are also highlighted. Our popular views of nature (i.e. stochastic and deterministic), and of geophysical phenomena in particular, are discussed, and the usefulness of chaos theory as a bridge between such views is also put forth

The electron capture in 163Ho experiment - ECHo

Science.gov (United States)

Gastaldo, L.; Blaum, K.; Chrysalidis, K.; Day Goodacre, T.; Domula, A.; Door, M.; Dorrer, H.; Düllmann, Ch. E.; Eberhardt, K.; Eliseev, S.; Enss, C.; Faessler, A.; Filianin, P.; Fleischmann, A.; Fonnesu, D.; Gamer, L.; Haas, R.; Hassel, C.; Hengstler, D.; Jochum, J.; Johnston, K.; Kebschull, U.; Kempf, S.; Kieck, T.; Köster, U.; Lahiri, S.; Maiti, M.; Mantegazzini, F.; Marsh, B.; Neroutsos, P.; Novikov, Yu. N.; Ranitzsch, P. C. O.; Rothe, S.; Rischka, A.; Saenz, A.; Sander, O.; Schneider, F.; Scholl, S.; Schüssler, R. X.; Schweiger, Ch.; Simkovic, F.; Stora, T.; Szücs, Z.; Türler, A.; Veinhard, M.; Weber, M.; Wegner, M.; Wendt, K.; Zuber, K.

2017-06-01

Neutrinos, and in particular their tiny but non-vanishing masses, can be considered one of the doors towards physics beyond the Standard Model. Precision measurements of the kinematics of weak interactions, in particular of the 3H β-decay and the 163Ho electron capture (EC), represent the only model independent approach to determine the absolute scale of neutrino masses. The electron capture in 163Ho experiment, ECHo, is designed to reach sub-eV sensitivity on the electron neutrino mass by means of the analysis of the calorimetrically measured electron capture spectrum of the nuclide 163Ho. The maximum energy available for this decay, about 2.8 keV, constrains the type of detectors that can be used. Arrays of low temperature metallic magnetic calorimeters (MMCs) are being developed to measure the 163Ho EC spectrum with energy resolution below 3 eV FWHM and with a time resolution below 1 μs. To achieve the sub-eV sensitivity on the electron neutrino mass, together with the detector optimization, the availability of large ultra-pure 163Ho samples, the identification and suppression of background sources as well as the precise parametrization of the 163Ho EC spectrum are of utmost importance. The high-energy resolution 163Ho spectra measured with the first MMC prototypes with ion-implanted 163Ho set the basis for the ECHo experiment. We describe the conceptual design of ECHo and motivate the strategies we have adopted to carry on the present medium scale experiment, ECHo-1K. In this experiment, the use of 1 kBq 163Ho will allow to reach a neutrino mass sensitivity below 10 eV/ c 2. We then discuss how the results being achieved in ECHo-1k will guide the design of the next stage of the ECHo experiment, ECHo-1M, where a source of the order of 1 MBq 163Ho embedded in large MMCs arrays will allow to reach sub-eV sensitivity on the electron neutrino mass.

The EChO science case

Science.gov (United States)

Tinetti, Giovanna; Drossart, Pierre; Eccleston, Paul; Hartogh, Paul; Isaak, Kate; Linder, Martin; Lovis, Christophe; Micela, Giusi; Ollivier, Marc; Puig, Ludovic; Ribas, Ignasi; Snellen, Ignas; Swinyard, Bruce; Allard, France; Barstow, Joanna; Cho, James; Coustenis, Athena; Cockell, Charles; Correia, Alexandre; Decin, Leen; de Kok, Remco; Deroo, Pieter; Encrenaz, Therese; Forget, Francois; Glasse, Alistair; Griffith, Caitlin; Guillot, Tristan; Koskinen, Tommi; Lammer, Helmut; Leconte, Jeremy; Maxted, Pierre; Mueller-Wodarg, Ingo; Nelson, Richard; North, Chris; Pallé, Enric; Pagano, Isabella; Piccioni, Guseppe; Pinfield, David; Selsis, Franck; Sozzetti, Alessandro; Stixrude, Lars; Tennyson, Jonathan; Turrini, Diego; Zapatero-Osorio, Mariarosa; Beaulieu, Jean-Philippe; Grodent, Denis; Guedel, Manuel; Luz, David; Nørgaard-Nielsen, Hans Ulrik; Ray, Tom; Rickman, Hans; Selig, Avri; Swain, Mark; Banaszkiewicz, Marek; Barlow, Mike; Bowles, Neil; Branduardi-Raymont, Graziella; du Foresto, Vincent Coudé; Gerard, Jean-Claude; Gizon, Laurent; Hornstrup, Allan; Jarchow, Christopher; Kerschbaum, Franz; Kovacs, Géza; Lagage, Pierre-Olivier; Lim, Tanya; Lopez-Morales, Mercedes; Malaguti, Giuseppe; Pace, Emanuele; Pascale, Enzo; Vandenbussche, Bart; Wright, Gillian; Ramos Zapata, Gonzalo; Adriani, Alberto; Azzollini, Ruymán; Balado, Ana; Bryson, Ian; Burston, Raymond; Colomé, Josep; Crook, Martin; Di Giorgio, Anna; Griffin, Matt; Hoogeveen, Ruud; Ottensamer, Roland; Irshad, Ranah; Middleton, Kevin; Morgante, Gianluca; Pinsard, Frederic; Rataj, Mirek; Reess, Jean-Michel; Savini, Giorgio; Schrader, Jan-Rutger; Stamper, Richard; Winter, Berend; Abe, L.; Abreu, M.; Achilleos, N.; Ade, P.; Adybekian, V.; Affer, L.; Agnor, C.; Agundez, M.; Alard, C.; Alcala, J.; Allende Prieto, C.; Alonso Floriano, F. J.; Altieri, F.; Alvarez Iglesias, C. A.; Amado, P.; Andersen, A.; Aylward, A.; Baffa, C.; Bakos, G.; Ballerini, P.; Banaszkiewicz, M.; Barber, R. J.; Barrado, D.; Barton, E. J.; Batista, V.; Bellucci, G.; Belmonte Avilés, J. A.; Berry, D.; Bézard, B.; Biondi, D.; Błęcka, M.; Boisse, I.; Bonfond, B.; Bordé, P.; Börner, P.; Bouy, H.; Brown, L.; Buchhave, L.; Budaj, J.; Bulgarelli, A.; Burleigh, M.; Cabral, A.; Capria, M. T.; Cassan, A.; Cavarroc, C.; Cecchi-Pestellini, C.; Cerulli, R.; Chadney, J.; Chamberlain, S.; Charnoz, S.; Christian Jessen, N.; Ciaravella, A.; Claret, A.; Claudi, R.; Coates, A.; Cole, R.; Collura, A.; Cordier, D.; Covino, E.; Danielski, C.; Damasso, M.; Deeg, H. J.; Delgado-Mena, E.; Del Vecchio, C.; Demangeon, O.; De Sio, A.; De Wit, J.; Dobrijévic, M.; Doel, P.; Dominic, C.; Dorfi, E.; Eales, S.; Eiroa, C.; Espinoza Contreras, M.; Esposito, M.; Eymet, V.; Fabrizio, N.; Fernández, M.; Femenía Castella, B.; Figueira, P.; Filacchione, G.; Fletcher, L.; Focardi, M.; Fossey, S.; Fouqué, P.; Frith, J.; Galand, M.; Gambicorti, L.; Gaulme, P.; García López, R. J.; Garcia-Piquer, A.; Gear, W.; Gerard, J.-C.; Gesa, L.; Giani, E.; Gianotti, F.; Gillon, M.; Giro, E.; Giuranna, M.; Gomez, H.; Gomez-Leal, I.; Gonzalez Hernandez, J.; González Merino, B.; Graczyk, R.; Grassi, D.; Guardia, J.; Guio, P.; Gustin, J.; Hargrave, P.; Haigh, J.; Hébrard, E.; Heiter, U.; Heredero, R. L.; Herrero, E.; Hersant, F.; Heyrovsky, D.; Hollis, M.; Hubert, B.; Hueso, R.; Israelian, G.; Iro, N.; Irwin, P.; Jacquemoud, S.; Jones, G.; Jones, H.; Justtanont, K.; Kehoe, T.; Kerschbaum, F.; Kerins, E.; Kervella, P.; Kipping, D.; Koskinen, T.; Krupp, N.; Lahav, O.; Laken, B.; Lanza, N.; Lellouch, E.; Leto, G.; Licandro Goldaracena, J.; Lithgow-Bertelloni, C.; Liu, S. J.; Lo Cicero, U.; Lodieu, N.; Lognonné, P.; Lopez-Puertas, M.; Lopez-Valverde, M. A.; Lundgaard Rasmussen, I.; Luntzer, A.; Machado, P.; MacTavish, C.; Maggio, A.; Maillard, J.-P.; Magnes, W.; Maldonado, J.; Mall, U.; Marquette, J.-B.; Mauskopf, P.; Massi, F.; Maurin, A.-S.; Medvedev, A.; Michaut, C.; Miles-Paez, P.; Montalto, M.; Montañés Rodríguez, P.; Monteiro, M.; Montes, D.; Morais, H.; Morales, J. C.; Morales-Calderón, M.; Morello, G.; Moro Martín, A.; Moses, J.; Moya Bedon, A.; Murgas Alcaino, F.; Oliva, E.; Orton, G.; Palla, F.; Pancrazzi, M.; Pantin, E.; Parmentier, V.; Parviainen, H.; Peña Ramírez, K. Y.; Peralta, J.; Perez-Hoyos, S.; Petrov, R.; Pezzuto, S.; Pietrzak, R.; Pilat-Lohinger, E.; Piskunov, N.; Prinja, R.; Prisinzano, L.; Polichtchouk, I.; Poretti, E.; Radioti, A.; Ramos, A. A.; Rank-Lüftinger, T.; Read, P.; Readorn, K.; Rebolo López, R.; Rebordão, J.; Rengel, M.; Rezac, L.; Rocchetto, M.; Rodler, F.; Sánchez Béjar, V. J.; Sanchez Lavega, A.; Sanromá, E.; Santos, N.; Sanz Forcada, J.; Scandariato, G.; Schmider, F.-X.; Scholz, A.; Scuderi, S.; Sethenadh, J.; Shore, S.; Showman, A.; Sicardy, B.; Sitek, P.; Smith, A.; Soret, L.; Sousa, S.; Stiepen, A.; Stolarski, M.; Strazzulla, G.; Tabernero, H. M.; Tanga, P.; Tecsa, M.; Temple, J.; Terenzi, L.; Tessenyi, M.; Testi, L.; Thompson, S.; Thrastarson, H.; Tingley, B. W.; Trifoglio, M.; Martín Torres, J.; Tozzi, A.; Turrini, D.; Varley, R.; Vakili, F.; de Val-Borro, M.; Valdivieso, M. L.; Venot, O.; Villaver, E.; Vinatier, S.; Viti, S.; Waldmann, I.; Waltham, D.; Ward-Thompson, D.; Waters, R.; Watkins, C.; Watson, D.; Wawer, P.; Wawrzaszk, A.; White, G.; Widemann, T.; Winek, W.; Wiśniowski, T.; Yelle, R.; Yung, Y.; Yurchenko, S. N.

2015-12-01

The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune—all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10-4 relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength

Assessment of groundwater potentiality using geophysical techniques in Wadi Allaqi basin, Eastern Desert, Egypt - Case study

Science.gov (United States)

Helaly, Ahmad Sobhy

2017-12-01

Electrical resistivity surveying has been carried out for the determination of the thickness and resistivity of layered media in Wadi Allaqi, Eastern Desert, Egypt. That is widely used geophysical tool for the purpose of assessing the groundwater potential and siting the best locations for boreholes in the unconfined Nubian Sandstone aquifers within the study area. This has been done using thirteen 1D Vertical Electrical Sounding (VES) surveys. 1D-VES surveys provide only layered model structures for the subsurface and do not provide comprehensive information for interpreting the structure and extent of subsurface hydro-geological features. The integration of two-dimensional (2D) geophysical techniques for groundwater prospecting has been done to provide a more detailed identification for the subsurface hydro-geological features from which potential sites for successful borehole locations are recognized. In addition, five magnetic profiles were measured for basement depth determination, expected geological structures and thickness of sedimentary succession that could include some basins suitable for groundwater accumulation as groundwater aquifers.

Unusual Radar Echo from the Wake of Meteor Fireball in Nearly

Directory of Open Access Journals (Sweden)

Young-Sook Lee

2018-06-01

Full Text Available The summer polar lower thermosphere (90–100 km has an interesting connection to meteors, adjacent to the mesopause region attaining the lowest temperature in summer. Meteors supply condensation nuclei for charged ice particles causing polar mesospheric summer echoes (PMSE. We report the observation of meteor trail with nearly horizontal transit at high speed (20–50 km/s, and at last with re-enhanced echo power followed by diffusive echoes. Changes in phase difference between radar receivers aligned in meridional and zonal directions are used to determine variations in horizontal displacements and speeds with respect to time by taking advantage of radar interferometric analysis. The actual transit of echo target is observed along the straight pathway vertically and horizontally extended as much as a distance of at least 24 km and at most 29 km. The meteor trail initially has a signature similar to ‘head echoes’, with travel speeds from 20 – 50 km/s. It subsequently transforms into a different type of echo target including specular echo and then finally the power reenhanced. The reenhancement of echo power is followed by fume-like diffusive echoes, indicating sudden release of plasma as like explosive process probably involved. We discuss a possible role of meteor-triggered secondary plasma trail, such as fireball embedded with electrical discharge that continuously varies the power and transit speed.

Polar mesosphere summer echoes (PMSE: Review of observations and current understanding

Directory of Open Access Journals (Sweden)

M. Rapp

2004-01-01

Full Text Available Polar mesosphere summer echoes (PMSE are very strong radar echoes primarily studied in the VHF wavelength range from altitudes close to the polar summer mesopause. Radar waves are scattered at irregularities in the radar refractive index which at mesopause altitudes is effectively determined by the electron number density. For efficient scatter, the electron number density must reveal structures at the radar half wavelength (Bragg condition for monostatic radars; ~3 m for typical VHF radars. The question how such small scale electron number density structures are created in the mesopause region has been a longstanding open scientific question for almost 30 years. This paper reviews experimental and theoretical milestones on the way to an advanced understanding of PMSE. Based on new experimental results from in situ observations with sounding rockets, ground based observations with radars and lidars, numerical simulations with microphysical models of the life cycle of mesospheric aerosol particles, and theoretical considerations regarding the diffusivity of electrons in the ice loaded complex plasma of the mesopause region, a consistent explanation for the generation of these radar echoes has been developed. The main idea is that mesospheric neutral air turbulence in combination with a significantly reduced electron diffusivity due to the presence of heavy charged ice aerosol particles (radii ~5–50 nm leads to the creation of structures at spatial scales significantly smaller than the inner scale of the neutral gas turbulent velocity field itself. Importantly, owing to their very low diffusivity, the plasma structures acquire a very long lifetime, i.e., 10 min to hours in the presence of particles with radii between 10 and 50 nm. This leads to a temporal decoupling of active neutral air turbulence and the existence of small scale plasma structures and PMSE and thus readily explains observations proving the absence of neutral air turbulence at

Echoes of the Great War: The recordings of African prisoners in the First World War

Directory of Open Access Journals (Sweden)

Anette Hoffmann

2014-10-01

Full Text Available Apart from army registers, some (often anonymous photographs and the files of anthropometric examination, the involvement of thousands of African soldiers in WWI and their presence in POW camps in Europe seems to have left few traces in European archives. Vis-à-vis a mass of autobiographic texts on the Great War, written by Europeans and Americans, there are very few published accounts of African soldiers that would allow for their historical experiences and views to be included in historiographies of WWI. A collection of sound recordings produced with African prisoners of war in German camps by a group of German linguists, musicologists and anthropologists between 1915-18 offers a notable documentation of their presence. Yet, similar to the anthropometric registration, these recordings were not designed to accommodate the soldiers’ accounts, but to create a collection of language recordings. If these cannot be considered as ‘authentic voices from the past’ and unmediated accounts of WWI, how do we understand and theorise these hitherto untranslated voice recordings, their form and content? This essay understands the recordings not as ‘voices’ but as echoes, that is, as mediated, often effaced reverberations of accounts of the self and the war. The notion of echo in this essay grapples with issues of extraction, attenuation, limitation, distance and distortion, or outright effacement, that is the result of the form and the mediation of those speech acts, the belatedness of listening to them, as well as, the gaps in meaning and intelligibility the recordings entail. By conceptualising the recorded voices and their translation as echoes, I seek to understand the status of the recordings, the effects of this linguistic practice and gain a sense of the situation in the camps, so as to position these subaltern articulations in their mediated, distorted form as part of the colonial archive.

Hierarchy of Loading Calculations | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

eff-date-range.png | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

PWS_Dashboard_2.png | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

eff-hover-chart.png | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

PWS_Dashboard_1.png | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

eff-toggle-chart.png | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Analyze Trends: State Hazardous Waste Dashboard | ECHO ...

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Custom Search Results Help | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Technical Users Background Document | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Black hole ringdown echoes and howls

Science.gov (United States)

Nakano, Hiroyuki; Sago, Norichika; Tagoshi, Hideyuki; Tanaka, Takahiro

2017-07-01

Recently the possibility of detecting echoes of ringdown gravitational waves from binary black hole mergers was shown. The presence of echoes is expected if the black hole is surrounded by a mirror that reflects gravitational waves near the horizon. Here, we present slightly more sophisticated templates motivated by a waveform which is obtained by solving the linear perturbation equation around a Kerr black hole with a complete reflecting boundary condition in the stationary traveling wave approximation. We estimate that the proposed template can bring about a 10% improvement in the signal-to-noise ratio.

Evolution of entanglement under echo dynamics

International Nuclear Information System (INIS)

Prosen, Tomaz; Znidaric, Marko; Seligman, Thomas H.

2003-01-01

Echo dynamics and fidelity are often used to discuss stability in quantum-information processing and quantum chaos. Yet fidelity yields no information about entanglement, the characteristic property of quantum mechanics. We study the evolution of entanglement in echo dynamics. We find qualitatively different behavior between integrable and chaotic systems on one hand and between random and coherent initial states for integrable systems on the other. For the latter the evolution of entanglement is given by a classical time scale. Analytic results are illustrated numerically in a Jaynes-Cummings model

Correction of echo shift in reconstruction processing for ultra-short TE pulse sequence

International Nuclear Information System (INIS)

Takizawa, Masahiro; Ootsuka, Takehiro; Abe, Takayuki; Takahashi, Tetsuhiko

2010-01-01

An ultra-short echo time (TE) pulse sequence is composed of a radial sampling that acquires echo signals radially in the K-space and a half-echo acquisition that acquires only half of the echo signal. The shift in the position of the echo signal (echo shift) caused by the timing errors in the gradient magnetic field pulses affects the image quality in the radial sampling with the half-echo acquisition. To improve image quality, we have developed a signal correction algorithm that detects and eliminates this echo shift during reconstruction by performing a pre-scan within 10 seconds. The results showed that image quality is improved under oblique and/or off-centering conditions that frequently cause image distortion due to hardware error. In conclusion, we have developed a robust ultra-short TE pulse sequence that allows wide latitude in the scan parameters, including oblique and off-centering conditions. (author)

Foley Sounds vs Real Sounds

DEFF Research Database (Denmark)

Trento, Stefano; Götzen, Amalia De

2011-01-01

This paper is an initial attempt to study the world of sound effects for motion pictures, also known as Foley sounds. Throughout several audio and audio-video tests we have compared both Foley and real sounds originated by an identical action. The main purpose was to evaluate if sound effects...

Annals of the International Geophysical Year solar radio emission during the International Geophysical Year

CERN Document Server

Smerd, S F

1969-01-01

Annals of the International Geophysical Year, Volume 34: Solar Radio Emission During the International Geophysical Year covers the significant solar radio emission events observed during the International Geophysical Year (IGY). This book is composed of six chapters, and begins with a summary of tabulated quantities describing solar radio emission during the IGY. The tabulated figures illustrate the method of recording the position of radio sources on the sun, the use of symbols in describing the structure of bursts observed at single frequencies, and the different types used in a spectral

E-region echo characteristics governed by auroral arc electrodynamics

Directory of Open Access Journals (Sweden)

S. E. Milan

2003-07-01

Full Text Available Observations of a pair of auroral arc features by two imagers, one ground- and one space-based, allows the associated field-aligned current (FAC and electric field structure to be inferred. Simultaneous observations of HF radar echoes provide an insight into the irregularity-generating mechanisms. This is especially interesting for the E-region echoes observed, which form the focus of our analysis, and from which several conclusions can be drawn, summarized as follows. Latitudinal variations in echo characteristics are governed by the FAC and electric field background. Particularly sharp boundaries are found at the edges of auroral arcs. Within regions of auroral luminosity, echoes have Doppler shifts below the ion-acoustic speed and are proportional to the electric field, suggesting scatter from gradient drift waves. Regions of downward FAC are associated with mixed high and low Doppler shift echoes. The high Doppler shift component is greatly in excess of the ion-acoustic speed, but seems to be commensurate with the driving electric field. The low Doppler shift component appears to be much depressed below expectations.Key words. Ionosphere (ionospheric irregularities; electric fields and currents

E-region echo characteristics governed by auroral arc electrodynamics

Directory of Open Access Journals (Sweden)

S. E. Milan

Full Text Available Observations of a pair of auroral arc features by two imagers, one ground- and one space-based, allows the associated field-aligned current (FAC and electric field structure to be inferred. Simultaneous observations of HF radar echoes provide an insight into the irregularity-generating mechanisms. This is especially interesting for the E-region echoes observed, which form the focus of our analysis, and from which several conclusions can be drawn, summarized as follows. Latitudinal variations in echo characteristics are governed by the FAC and electric field background. Particularly sharp boundaries are found at the edges of auroral arcs. Within regions of auroral luminosity, echoes have Doppler shifts below the ion-acoustic speed and are proportional to the electric field, suggesting scatter from gradient drift waves. Regions of downward FAC are associated with mixed high and low Doppler shift echoes. The high Doppler shift component is greatly in excess of the ion-acoustic speed, but seems to be commensurate with the driving electric field. The low Doppler shift component appears to be much depressed below expectations.

Key words. Ionosphere (ionospheric irregularities; electric fields and currents

Investigating the Group-Level Impact of Advanced Dual-Echo fMRI Combinations

Directory of Open Access Journals (Sweden)

Adam Kettinger

2016-12-01

Full Text Available Multi-echo fMRI data acquisition has been widely investigated and suggested to optimize sensitivity for detecting the BOLD signal. Several methods have also been proposed for the combination of data with different echo times. The aim of the present study was to investigate how these advance echo combination methods provide advantages over the simple averaging of echoes when state-of-the-art group-level random-effect analyses are performed. Both resting-state and task-based dual-echo fMRI data were collected from 27 healthy adult individuals (14 male, mean age = 25.75 years using standard echo-planar acquisition methods at 3T. Both resting-state and task-based data were subjected to a standard image pre-processing pipeline. Subsequently the two echoes were combined as a weighted average, using four different strategies for calculating the weights: (1 simple arithmetic averaging, (2 BOLD sensitivity weighting, (3 temporal-signal-to-noise ratio weighting and (4 temporal BOLD sensitivity weighting. Our results clearly show that the simple averaging of data with the different echoes is sufficient. Advanced echo combination methods may provide advantages on a single-subject level but when considering random-effects group level statistics they provide no benefit regarding sensitivity (i.e. group-level t-values compared to the simple echo-averaging approach. One possible reason for the lack of clear advantages may be that apart from increasing the average BOLD sensitivity at the single-subject level, the advanced weighted averaging methods also inflate the inter-subject variance. As the echo combination methods provide very similar results, the recommendation is to choose between them depending on the availability of time for collecting additional resting-state data or whether subject-level or group-level analyses are planned.

The marine digital terrain model of the Panarea caldera (Aeolian Islands, Southern Italy

Directory of Open Access Journals (Sweden)

M. Anzidei

1998-06-01

Full Text Available A Marine Digital Elevation Model (MDEM of the still active volcanic area of Panarea caldera is presented in this paper. A fast and accurate survey was performed by means of the Differential Global Positioning System (DGPS geodetic technique coupled with an echo-sounding gear and a real time navigation software. The instrumentation was installed on board of a low draught boat in order to collect data starting from the bathymeter of one meter. Planar positions and depths were obtained with average accuracies of 30 cm and 10 cm respectively providing a 3D map of the seafloor useful for geomorphological, geophysical and volcanic hazard applications.

Visual Perceptual Echo Reflects Learning of Regularities in Rapid Luminance Sequences.

Science.gov (United States)

Chang, Acer Y-C; Schwartzman, David J; VanRullen, Rufin; Kanai, Ryota; Seth, Anil K

2017-08-30

A novel neural signature of active visual processing has recently been described in the form of the "perceptual echo", in which the cross-correlation between a sequence of randomly fluctuating luminance values and occipital electrophysiological signals exhibits a long-lasting periodic (∼100 ms cycle) reverberation of the input stimulus (VanRullen and Macdonald, 2012). As yet, however, the mechanisms underlying the perceptual echo and its function remain unknown. Reasoning that natural visual signals often contain temporally predictable, though nonperiodic features, we hypothesized that the perceptual echo may reflect a periodic process associated with regularity learning. To test this hypothesis, we presented subjects with successive repetitions of a rapid nonperiodic luminance sequence, and examined the effects on the perceptual echo, finding that echo amplitude linearly increased with the number of presentations of a given luminance sequence. These data suggest that the perceptual echo reflects a neural signature of regularity learning.Furthermore, when a set of repeated sequences was followed by a sequence with inverted luminance polarities, the echo amplitude decreased to the same level evoked by a novel stimulus sequence. Crucially, when the original stimulus sequence was re-presented, the echo amplitude returned to a level consistent with the number of presentations of this sequence, indicating that the visual system retained sequence-specific information, for many seconds, even in the presence of intervening visual input. Altogether, our results reveal a previously undiscovered regularity learning mechanism within the human visual system, reflected by the perceptual echo. SIGNIFICANCE STATEMENT How the brain encodes and learns fast-changing but nonperiodic visual input remains unknown, even though such visual input characterizes natural scenes. We investigated whether the phenomenon of "perceptual echo" might index such learning. The perceptual echo is a

78 FR 13869 - Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy...

Science.gov (United States)

2013-03-01

...-123-LNG; 12-128-NG; 12-148-NG; 12- 158-NG] Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; CE FLNG, LLC; Consolidated...-NG Puget Sound Energy, Inc Order granting long- term authority to import/export natural gas from/to...

A computational model for biosonar echoes from foliage.

Directory of Open Access Journals (Sweden)

Chen Ming

Full Text Available Since many bat species thrive in densely vegetated habitats, echoes from foliage are likely to be of prime importance to the animals' sensory ecology, be it as clutter that masks prey echoes or as sources of information about the environment. To better understand the characteristics of foliage echoes, a new model for the process that generates these signals has been developed. This model takes leaf size and orientation into account by representing the leaves as circular disks of varying diameter. The two added leaf parameters are of potential importance to the sensory ecology of bats, e.g., with respect to landmark recognition and flight guidance along vegetation contours. The full model is specified by a total of three parameters: leaf density, average leaf size, and average leaf orientation. It assumes that all leaf parameters are independently and identically distributed. Leaf positions were drawn from a uniform probability density function, sizes and orientations each from a Gaussian probability function. The model was found to reproduce the first-order amplitude statistics of measured example echoes and showed time-variant echo properties that depended on foliage parameters. Parameter estimation experiments using lasso regression have demonstrated that a single foliage parameter can be estimated with high accuracy if the other two parameters are known a priori. If only one parameter is known a priori, the other two can still be estimated, but with a reduced accuracy. Lasso regression did not support simultaneous estimation of all three parameters. Nevertheless, these results demonstrate that foliage echoes contain accessible information on foliage type and orientation that could play a role in supporting sensory tasks such as landmark identification and contour following in echolocating bats.

Echo questions as a means of building coherence in conversational discourse

Directory of Open Access Journals (Sweden)

Strelchenko Natalia

2017-06-01

Full Text Available The study focuses on the cognitive-communicative characteristics of echo questions in English conversational discourse. Drawing on van Dijk's sociocognitive (mental model theory and cognitive discourse analysis, the paper suggests viewing echo questions as a means of building/updating a mental context model of a communicative situation. As discourse comprehension presupposes building its coherent mental model, echo questions resolving misunderstanding are regarded as an instrument for increasing coherence in conversational discourse. Based on the mental model theory, the study offers a typology of misunderstandings corrected by echo questions.

Self-normalizing multiple-echo technique for measuring the in vivo apparent diffusion coefficient

International Nuclear Information System (INIS)

Perman, W.H.; Gado, M.; Sandstrom, J.C.

1989-01-01

This paper presents work to develop a new technique for quantitating the in vivo apparent diffusion/perfusion coefficient (ADC) by obtaining multiple data points from only two images with the capability to normalize the data from consecutive images, thus minimizing the effect of interimage variation. Two multiple-echo (six-to eight-echo) cardiac-gated images are obtained, one without and one with additional diffusion/perfusion encoding gradients placed about the 180 RF pulses of all but the first echo. Since the first echoes of both images have identical pulse sequence parameters, variations in signal intensity-between the first echoes represent image-to-image variation. The signal intensities of the subsequent echoes with additional diffusion/perfusion encoding gradients are then normalized by using the ratio of the first-echo signal intensities

Diagnostic accuracy of dual-echo (in- and opposed-phase) T1-weighted gradient recalled echo for detection and grading of hepatic iron using quantitative and visual assessment

Energy Technology Data Exchange (ETDEWEB)

Schieda, Nicola; Ramanathan, Subramaniyan; Ryan, John; Khanna, Maneesh; Virmani, Vivek; Avruch, Leonard [The University of Ottawa, The Ottawa Hospital, Ottawa, Ontario (Canada)

2014-07-15

Detection and quantification of hepatic iron with dual-echo gradient recalled echo (GRE) has been proposed as a rapid alternative to other magnetic resonance imaging (MRI) techniques. Co-existing steatosis and T1 weighting are limitations. This study assesses the accuracy of routine dual-echo GRE. Between 2010 and 2013, 109 consecutive patients underwent multi-echo (ME) MRI and dual-echo GRE for quantification of hepatic iron. Liver iron concentration (LIC) was calculated from ME-MRI. Relative signal intensity (RSI) and fat signal fraction (FSF) were calculated from dual-echo GRE. Four radiologists subjectively evaluated dual-echo GRE (±subtraction). Diagnostic accuracy was compared between techniques and correlated with biopsy using Fisher's exact test, Spearman correlation and regression. The sensitivity of visual detection of iron ranged from 48 to 55 %. Subtraction did not increase sensitivity (p < 0.001). Inter-observer variability was substantial (κ = 0.72). The specificity of visual detection of iron approached 100 % with false-positive diagnoses observed using subtraction. LIC showed a higher correlation with histopathological iron grade (r = 0.94, p < 0.001) compared with RSI (r = 0.65, p = 0.02). Univariate regression showed an association between RSI and LIC (B = 0.98, p < 0.001, CI 0.73-1.23); however, the association was not significant with multi-variate regression including FSF (p = 0.28). Dual-echo GRE has low sensitivity for hepatic iron. Subtraction imaging can result in false-positive diagnoses. (orig.)

Environmental Geophysical Study of the Groundwater Mineralization in a Plot of the Cotonou Littoral Zone (South Benin

Directory of Open Access Journals (Sweden)

Yalo Nicaise

2012-01-01

Full Text Available Geophysical investigations comprising electrical resistivity and electromagnetic conductivities methods were deployed in a 350 m2 sector, strewn with 11 wells. Within the framework of an environmental study on a small scale in the south of Benin, the water conductivity of these wells was measured to determine in a direct way mineralization of the coastal water table in the littoral zone. This environmental study aimed to prospect by the geophysical methods the space extension of the water table mineralization obtained by direct measurements of water conductivity in the well and the depth of the fresh water/salted water interface in the coastal aquifer. Electromagnetic measurements of conductivities made it possible to chart a gradient of mineralization in the northwest direction. The logs of vertical electric soundings showed a deepening of the fresh water/salted water interface in the southern part and its rupture in the northern part. The electrical resistivities of the interface are sensitive to the degree of its mineralization. It has been observed that the geophysical methods in electrical and electromagnetic prospection are a great contribution to the environmental study of the water table mineralization in the littoral zone for a sustainable management of the water resource.

Efficiency Evaluation of Handling of Geologic-Geophysical Information by Means of Computer Systems

Science.gov (United States)

Nuriyahmetova, S. M.; Demyanova, O. V.; Zabirova, L. M.; Gataullin, I. I.; Fathutdinova, O. A.; Kaptelinina, E. A.

2018-05-01

Development of oil and gas resources, considering difficult geological, geographical and economic conditions, requires considerable finance costs; therefore their careful reasons, application of the most perspective directions and modern technologies from the point of view of cost efficiency of planned activities are necessary. For ensuring high precision of regional and local forecasts and modeling of reservoirs of fields of hydrocarbonic raw materials, it is necessary to analyze huge arrays of the distributed information which is constantly changing spatial. The solution of this task requires application of modern remote methods of a research of the perspective oil-and-gas territories, complex use of materials remote, nondestructive the environment of geologic-geophysical and space methods of sounding of Earth and the most perfect technologies of their handling. In the article, the authors considered experience of handling of geologic-geophysical information by means of computer systems by the Russian and foreign companies. Conclusions that the multidimensional analysis of geologicgeophysical information space, effective planning and monitoring of exploration works requires broad use of geoinformation technologies as one of the most perspective directions in achievement of high profitability of an oil and gas industry are drawn.

Geophysical images of basement rocks. Geophysical images in the Guianese basement. Airborne geophysical campaign in French Guiana - 1996

International Nuclear Information System (INIS)

Delor, C.; Perrin, J.; Truffert, C.; Asfirane, F.; Rossi, Ph.; Bonjoly, D.; Dubreuihl, J.; Chardon, D.

1998-01-01

The French Office for Geological and Mining Research (BRGM) has carried out a high sensitivity airborne geophysical survey of northern French Guiana during the second half of 1996. The aim was to realize a high resolution magnetic and gamma spectrometric mapping for future prospecting, land use and environment management. This paper describes in details the geophysical campaign, the material used, the navigation techniques, the processing of magnetic data, the gamma radiation sources used, the spectrometric calibrations and the geologic interpretation of the results. (J.S.)

Introduction to the JEEG Agricultural Geophysics Special Issue

Science.gov (United States)

Allred, Barry J.; Smith, Bruce D.

2010-01-01

Near-surface geophysical methods have become increasingly important tools in applied agricultural practices and studies. The great advantage of geophysical methods is their potential rapidity, low cost, and spatial continuity when compared to more traditional methods of assessing agricultural land, such as sample collection and laboratory analysis. Agricultural geophysics investigations commonly focus on obtaining information within the soil profile, which generally does not extend much beyond 2 meters beneath the ground surface. Although the depth of interest oftentimes is rather shallow, the area covered by an agricultural geophysics survey can vary widely in scale, from experimental plots (10 s to 100 s of square meters), to farm fields (10 s to 100 s of hectares), up to the size of watersheds (10 s to 100 s of square kilometers). To date, three predominant methods—resistivity, electromagnetic induction (EMI), and ground-penetrating radar (GPR)—have been used to obtain surface-based geophysical measurements within agricultural settings. However, a recent conference on agricultural geophysics (Bouyoucos Conference on Agricultural Geophysics, September 8–10, 2009, Albuquerque, New Mexico; www.ag-geophysics.org) illustrated that other geophysical methods are being applied or developed. These include airborne electromagnetic induction, magnetometry, seismic, and self-potential methods. Agricultural geophysical studies are also being linked to ground water studies that utilize deeper penetrating geophysical methods than normally used.

Acoustic and geophysical measurement of infrasound from turbines at wind farms

Energy Technology Data Exchange (ETDEWEB)

Hepburn, H.G. [Hepburn Exploration Inc., Canmore, AB (Canada)

2005-07-01

An experiment was conducted at the Castle River Wind Farm in southern Alberta to measure and characterize infrasound from the turbines. The wind farm contains one 600 MW turbine and fifty-nine 660 MW wind turbines. Three types of sensors were used to measure both the low and high frequency acoustic energy and geophysical sound levels. These included low frequency geophones, acoustic microphones and a precision sound analyzer. Data was recorded for low, medium and high wind states, with the entire wind turbine array operating, and with the entire wind farm stopped. Downwind telemetry measurements were recorded for 30 continuous 50 metre offsets, up to a distance of 1450 metres from the wind farm. The objective of the project was to characterize the ambient noise levels and sound emitted by the turbines. Measurements were taken for wind speed and direction, atmospheric pressure, atmospheric temperature and turbine related data. Visual observations included atmospheric conditions, extraneous sources of noise such as aircraft, trains, motor vehicle traffic, highway noise, bird song, crickets and the rotational state of the turbines. It was concluded that for studying low frequency sound, the linear dB scale should be used instead of the dBA scale. Measurements of frequencies down to 6.3 Hz, showed that infrasound emission from the Castle River Wind Farm is not a significant concern. Lower frequencies down to about 2.5 Hz also confirmed that infrasound emissions are not significantly above the ambient noise levels. Any infrasound emissions were strongly coupled to the ground and were attenuated quickly. Time domain measurements showed that at all wind speeds and for frequencies up to 270 Hz, wind noise was actually attenuated when the wind farm is in operation. The noise levels were higher when the turbines were not turning. This finding was confirmed through spectral analysis. 12 refs., 2 tabs., 46 figs.

Geophysical Institute. Biennial report, 1993-1994

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-01-01

The 1993-1994 Geophysical Institute Biennial Report was published in November 1995 by the Geophysical Institute of the University of Alaska Fairbanks. It contains an overview of the Geophysical Institute, the Director`s Note, and research presentations concerning the following subjects: Scientific Predictions, Space Physics, Atmospheric Sciences, Snow, Ice and Permafrost, Tectonics and Sedimentation, Seismology, Volcanology, Remote Sensing, and other projects.

Variable-flip-angle spin-echo imaging (VFSE)

International Nuclear Information System (INIS)

Kasai, Toshifumi; Sugimura, Kazuro; Kawamitsu, Hideaki; Yasui, Kiyoshi; Ishida, Tetsuya; Tsukamoto, Tetsuji.

1990-01-01

T 2 weighted imaging provides images with high object contrast for pathologic conditions in which the water content of tissues is increased. The authors predicted theoretical analysis of the effects of changing flip angle, and analyzed the effects in MR imaging of both phantoms and humans. Variable flip angle spin echo MR imaging (VFSE) with a 1,000/80 (repetition time msec/echo time msec) can obtain T 2 weighted image when flip angle is smaller than 80 degrees. VFSE with 40 to 60 degrees flip angle have higher contrast than other flip angle images. Signal to noise ratio (S/N) of VFSE are 55% at a 30 degree, 76% at a 45 degree, 92% at a 60 degree respectively as compared with conventional spin echo image (2000/80, flip angle 90 degree). VFSE is applicable to obtain T 2 weighted image reduced imaging time. (author)

New spoiled spin-echo technique for three-dimensional MR imaging

International Nuclear Information System (INIS)

Darrasse, L.; Mao, L.; Saint-Jalmes, H.

1989-01-01

For 3D MR imaging within a convenient scanning time, the authors propose an improved spin-echo technique that permits the use of TRs shorter than 100 msec. They use a two-pulse RF sequence (α-π echo). The echo is read with conventional 3DFT encoding. To avoid steady-state signal refocusing before either α or (imperfect) π pulses, we apply randomized gradient spoilers both before each α pulse and on each side of the π pulse. So the sequence works like standard spin- echo sequences, with the z-magnetization recovery being adjusted by means of α rather than TR. The authors have investigated the method on a new 0.1-T Magnetom system dedicated for 3D MR imaging

Classification of underwater target echoes based on auditory perception characteristics

Science.gov (United States)

Li, Xiukun; Meng, Xiangxia; Liu, Hang; Liu, Mingye

2014-06-01

In underwater target detection, the bottom reverberation has some of the same properties as the target echo, which has a great impact on the performance. It is essential to study the difference between target echo and reverberation. In this paper, based on the unique advantage of human listening ability on objects distinction, the Gammatone filter is taken as the auditory model. In addition, time-frequency perception features and auditory spectral features are extracted for active sonar target echo and bottom reverberation separation. The features of the experimental data have good concentration characteristics in the same class and have a large amount of differences between different classes, which shows that this method can effectively distinguish between the target echo and reverberation.

Dynamic rayed aurora and enhanced ion-acoustic radar echoes

Directory of Open Access Journals (Sweden)

E. M. Blixt

2005-01-01

Full Text Available The generation mechanism for naturally enhanced ion-acoustic echoes is still debated. One important issue is how these enhancements are related to auroral activity. All events of enhanced ion-acoustic echoes observed simultaneously with the EISCAT Svalbard Radar (ESR and with high-resolution narrow field-of-view auroral imagers have been collected and studied. Characteristic of all the events is the appearance of very dynamic rayed aurora, and some of the intrinsic features of these auroral displays are identified. Several of these identified features are directly related to the presence of low energy (10-100eV precipitating electrons in addition to the higher energy population producing most of the associated light. The low energy contribution is vital for the formation of the enhanced ion-acoustic echoes. We argue that this type of aurora is sufficient for the generation of naturally enhanced ion-acoustic echoes. In one event two imagers were used to observe the auroral rays simultaneously, one from the radar site and one 7km away. The data from these imagers shows that the auroral rays and the strong backscattering filaments (where the enhanced echoes are produced are located on the same field line, which is in contrast to earlier statements in the litterature that they should be separated.

Faraday rotation echo spectroscopy and detection of quantum fluctuations.

Science.gov (United States)

Chen, Shao-Wen; Liu, Ren-Bao

2014-04-15

Central spin decoherence is useful for detecting many-body physics in environments and moreover, the spin echo control can remove the effects of static thermal fluctuations so that the quantum fluctuations are revealed. The central spin decoherence approach, however, is feasible only in some special configurations and often requires uniform coupling between the central spin and individual spins in the baths, which are very challenging in experiments. Here, by making analogue between central spin decoherence and depolarization of photons, we propose a scheme of Faraday rotation echo spectroscopy (FRES) for studying quantum fluctuations in interacting spin systems. The echo control of the photon polarization is realized by flipping the polarization with a birefringence crystal. The FRES, similar to spin echo in magnetic resonance spectroscopy, can suppress the effects of the static magnetic fluctuations and therefore reveal dynamical magnetic fluctuations. We apply the scheme to a rare-earth compound LiHoF4 and calculate the echo signal, which is related to the quantum fluctuations of the system. We observe enhanced signals at the phase boundary. The FRES should be useful for studying quantum fluctuations in a broad range of spin systems, including cold atoms, quantum dots, solid-state impurities, and transparent magnetic materials.

MR contrast of ferritin and hemosiderin in the brain: comparison among gradient-echo, conventional spin-echo and fast spin-echo sequences

Energy Technology Data Exchange (ETDEWEB)

Haque, Tabassum Laz; Miki, Yukio; Kanagaki, Mitsunori; Takahashi, Takahiro; Yamamoto, Akira; Konishi, Junya; Nozaki, Kazuhiko; Hashimoto, Nobuo; Konishi, Junji

2003-12-01

Objective: To compare the magnetic resonance image contrasts due to ferritin and hemosiderin in the brain tissue among different pulse sequences. Materials and methods: Fourteen patients with cavernous hemangioma in the brain prospectively underwent MR imaging with T2*-weighted gradient-echo (GRE), T2-weighted conventional spin-echo (SE) and fast spin-echo (FSE) sequences. The relative contrast ratios (CRs) of the hypointense part of cavernous hemangioma, globus pallidus and putamen to the deep frontal white matter were measured on each pulse sequence and statistically analyzed using analysis of variance followed by paired t-test. Results: In the hypointense part of cavernous hemangioma, relative CRs were significantly lower on T2*-weighted GRE than on T2-weighted SE images (P=0.0001), and on T2-weighted SE than on T2-weighted FSE images (P=0.0001). In the globus pallidus, relative CRs were significantly lower on T2-weighted SE than on T2*-weighted GRE images (P=0.002), and on T2*-weighted GRE than on T2-weighted FSE images (P=0.0002). In the putamen, relative CRs were significantly lower on T2-weighted SE than on T2*-weighted GRE images (P=0.001), and there was no significant difference between CRs on T2-weighted FSE and T2*-weighted GRE images (P=0.90). Conclusion: Hemosiderin showed best image contrast on T2*-weighted GRE images but ferritin showed more prominent image contrast on T2-weighted SE than on T2*-weighted GRE images, which may help to determine an appropriate pulse sequence in neurological diseases associated with excessive ferritin accumulation.

MR contrast of ferritin and hemosiderin in the brain: comparison among gradient-echo, conventional spin-echo and fast spin-echo sequences

International Nuclear Information System (INIS)

Haque, Tabassum Laz; Miki, Yukio; Kanagaki, Mitsunori; Takahashi, Takahiro; Yamamoto, Akira; Konishi, Junya; Nozaki, Kazuhiko; Hashimoto, Nobuo; Konishi, Junji

2003-01-01

Objective: To compare the magnetic resonance image contrasts due to ferritin and hemosiderin in the brain tissue among different pulse sequences. Materials and methods: Fourteen patients with cavernous hemangioma in the brain prospectively underwent MR imaging with T2*-weighted gradient-echo (GRE), T2-weighted conventional spin-echo (SE) and fast spin-echo (FSE) sequences. The relative contrast ratios (CRs) of the hypointense part of cavernous hemangioma, globus pallidus and putamen to the deep frontal white matter were measured on each pulse sequence and statistically analyzed using analysis of variance followed by paired t-test. Results: In the hypointense part of cavernous hemangioma, relative CRs were significantly lower on T2*-weighted GRE than on T2-weighted SE images (P=0.0001), and on T2-weighted SE than on T2-weighted FSE images (P=0.0001). In the globus pallidus, relative CRs were significantly lower on T2-weighted SE than on T2*-weighted GRE images (P=0.002), and on T2*-weighted GRE than on T2-weighted FSE images (P=0.0002). In the putamen, relative CRs were significantly lower on T2-weighted SE than on T2*-weighted GRE images (P=0.001), and there was no significant difference between CRs on T2-weighted FSE and T2*-weighted GRE images (P=0.90). Conclusion: Hemosiderin showed best image contrast on T2*-weighted GRE images but ferritin showed more prominent image contrast on T2-weighted SE than on T2*-weighted GRE images, which may help to determine an appropriate pulse sequence in neurological diseases associated with excessive ferritin accumulation

Characterization of echoes: A Dyson-series representation of individual pulses

Science.gov (United States)

Correia, Miguel R.; Cardoso, Vitor

2018-04-01

The ability to detect and scrutinize gravitational waves from the merger and coalescence of compact binaries opens up the possibility to perform tests of fundamental physics. One such test concerns the dark nature of compact objects: are they really black holes? It was recently pointed out that the absence of horizons—while keeping the external geometry very close to that of General Relativity—would manifest itself in a series of echoes in gravitational wave signals. The observation of echoes by LIGO/Virgo or upcoming facilities would likely inform us on quantum gravity effects or unseen types of matter. Detection of such signals is in principle feasible with relatively simple tools but would benefit enormously from accurate templates. Here we analytically individualize each echo waveform and show that it can be written as a Dyson series, for arbitrary effective potential and boundary conditions. We further apply the formalism to explicitly determine the echoes of a simple toy model: the Dirac delta potential. Our results allow to read off a few known features of echoes and may find application in the modeling for data analysis.

Predictive geophysics: geochemical simulations to geophysical targets

Science.gov (United States)

Chopping, R. G.; Cleverley, J.

2017-12-01

With an increasing focus on deep exploration for covered targets, new methods are required to target mineral systems under cover. Geophysical responses are driven by physical property contrasts; for example, density contrasts provide a gravity signal, acoustic impedance contrasts provide a seismic reflection signal. In turn, the physical properties for basement, crystalline rocks which host the vast majority of mineral systems are determined almost wholly by the mineralogy of the rocks in question. Mineral systems, through the transport of heat and reactive fluids, will serve to modify the physical properties of country rock as they chemically alter the hosting strata. To understand these changes, we have performed 2D reactive transport modelling that simulates the formation of Archean gold deposits of the Yilgarn Craton, Western Australia. From this, we derive a model of mineralogy that we can use to predict the density, magnetic susceptibility and seismic reflection changes associated with ore formation. It is then possible to predict the gravity, magnetic and seismic reflection responses associated with these deposits. Scenario mapping, such as testing the ability to resolve buried ore bodies or the geophysical survey spacing required to resolve the mineral system, can be performed to produce geophysical targets from these geochemical simulations. We find that there is a gravity response of around 9% of the unaltered response for deposits even buried by 1km of cover, and there is a magnetic spike associated with proximal alteration of the ore system. Finally, seismic reflection response is mostly characterised by additional reflections along faults that plumb the alteration system.

A Pilot Study Assessing ECG versus ECHO Ventriculoventricular Optimization in Pediatric Resynchronization Patients.

Science.gov (United States)

Punn, Rajesh; Hanisch, Debra; Motonaga, Kara S; Rosenthal, David N; Ceresnak, Scott R; Dubin, Anne M

2016-02-01

Cardiac resynchronization therapy indications and management are well described in adults. Echocardiography (ECHO) has been used to optimize mechanical synchrony in these patients; however, there are issues with reproducibility and time intensity. Pediatric patients add challenges, with diverse substrates and limited capacity for cooperation. Electrocardiographic (ECG) methods to assess electrical synchrony are expeditious but have not been extensively studied in children. We sought to compare ECHO and ECG CRT optimization in children. Prospective, pediatric, single-center cross-over trial comparing ECHO and ECG optimization with CRT. Patients were assigned to undergo either ECHO or ECG optimization, followed for 6 months, and crossed-over to the other assignment for another 6 months. ECHO pulsed-wave tissue Doppler and 12-lead ECG were obtained for 5 VV delays. ECG optimization was defined as the shortest QRSD and ECHO optimization as the lowest dyssynchrony index. ECHOs/ECGs were interpreted by readers blinded to optimization technique. After each 6 month period, these data were collected: ejection fraction, velocimetry-derived cardiac index, quality of life, ECHO-derived stroke distance, M-mode dyssynchrony, study cost, and time. Outcomes for each optimization method were compared. From June 2012 to December 2013, 19 patients enrolled. Mean age was 9.1 ± 4.3 years; 14 (74%) had structural heart disease. The mean time for optimization was shorter using ECG than ECHO (9 ± 1 min vs. 68 ± 13 min, P cost for charges was $4,400 ± 700 less for ECG. No other outcome differed between groups. ECHO optimization of synchrony was not superior to ECG optimization in this pilot study. ECG optimization required less time and cost than ECHO optimization. © 2015 Wiley Periodicals, Inc.

Velocities of Auroral Coherent Echoes At 12 and 144 Mhz

Science.gov (United States)

Koustov, A. V.; Danskin, D. W.; Makarevitch, R. A.; Uspensky, M. V.; Janhunen, P.; Nishitani, N.; Nozawa, N.; Lester, M.; Milan, S.

Two Doppler coherent radar systems are currently working at Hankasalmi, Finland, the STARE and CUTLASS radars operating at 144 MHz and 12 MHz, respectively. The STARE beam 3 is nearly co-located with the CUTLASS beam 5 providing an opportunity for echo velocity comparison along the same direction but at significantly different radar frequencies. In this study we consider one event when STARE radar echoes are detected t the same ranges as CUTLASS radar echoes. The observations are complemented by EISCAT measurements of the ionospheric electric field and elec- tron density behavior at one range of 900 km. Two separate situations are studied; for the first one, CUTLASS observed F-region echoes (including the range of the EIS- CAT measurements) while for the second one CUTLASS observed E-region echoes. In both cases STARE E-region measurements were available. We show that F-region CUTLASS velocities agree well with the convection component along the CUTLASS radar beam while STARE velocities are sometimes smaller by a factor of 2-3. For the second case, STARE velocities are found to be either smaller or larger than CUTLASS velocities, depending on range. Plasma physics of E- and F-region irregularities is dis- cussed in attempt to explain inferred relationship between various velocities. Special attention is paid to ionospheric refraction that is important for the detection of 12-MHz echoes.

Short term memory in echo state networks

OpenAIRE

Jaeger, H.

2001-01-01

The report investigates the short-term memory capacity of echo state recurrent neural networks. A quantitative measure MC of short-term memory capacity is introduced. The main result is that MC 5 N for networks with linear Output units and i.i.d. input, where N is network size. Conditions under which these maximal memory capacities are realized are described. Several theoretical and practical examples demonstrate how the short-term memory capacities of echo state networks can be exploited for...

Speed of sound in saturated aliphatic alcohols (propan-2-ol, butan-2-ol, and 2-methylpropan-1-ol) and alkanediols (ethane-1,2-diol, propane-1,2- and -1,3-diol) at temperature between 253.15 K and 353.15 K and pressures up to 30 MPa

International Nuclear Information System (INIS)

Dávila, María J.; Gedanitz, Holger; Span, Roland

2016-01-01

Highlights: • Speed of sound measurements were made in aliphatic alcohols and alkanediols. • Speeds of sound were measured in a wide temperature and pressure range. • A pulse-echo method with a double path type sensor operating at 8 MHz was employed. • A double polynomial equation was used to fit the experimental speed of sound data. • The accurate results were compared with available literature sources. - Abstract: Speeds of sound have been measured in three saturated aliphatic alcohols (propan-2-ol, butan-2-ol, and 2-methylpropan-1-ol) and three alkanediols (ethane-1,2-diol, propane-1,2- and -1,3-diol) in the temperature range from (253.15 to 353.15) K and pressures up to 30 MPa by use of a pulse-echo method with a double path type sensor operating at 8 MHz. The expanded overall uncertainties (k = 2) in the speed of sound measurements are estimated to be 0.013% for propan-2-ol, 0.019% for butan-2-ol, 0.01% for 2-methylpropan-1-ol, 0.009% for ethane-1,2-diol, 0.02% for propane-1,2-diol, and 0.07% for propane-1,3-diol. Experimental speeds of sound data were correlated with the temperature and pressure with an empirical double polynomial equation. Our results were also compared with the available literature data and a satisfactory agreement was found.

Synthesis of the works of geophysical (electrical soundings) carried out in the region of the anomalies of Yerba Sola (Cerro Largo) Uruguay

International Nuclear Information System (INIS)

Perrin, J.

1983-01-01

In this report has been studied geographical localization, geology, geophysics prospection, equipment and methods used and their results in Yerba Sola anomalies Province Cerro Largo and Fraile Muerto formation

Relativistic electron dropout echoes induced by interplanetary shocks

Science.gov (United States)

Schiller, Q.; Kanekal, S. G.; Boyd, A. J.; Baker, D. N.; Blake, J. B.; Spence, H. E.

2017-12-01

Interplanetary shocks that impact Earth's magnetosphere can produce immediate and dramatic responses in the trapped relativistic electron population. One well-studied response is a prompt injection capable of transporting relativistic electrons deep into the magnetosphere and accelerating them to multi-MeV energies. The converse effect, electron dropout echoes, are observations of a sudden dropout of electron fluxes observed after the interplanetary shock arrival. Like the injection echo signatures, dropout echoes can also show clear energy dispersion signals. They are of particular interest because they have only recently been observed and their causal mechanism is not well understood. In the analysis presented here, we show observations of electron drift echo signatures from the Relativistic Electron-Proton Telescope (REPT) and Magnetic Electron and Ion Sensors (MagEIS) onboard NASA's Van Allen Probes mission, which show simultaneous prompt enhancements and dropouts within minutes of the associated with shock impact. We show that the observations associated with both enhancements and dropouts are explained by the inward motion caused by the electric field impulse induced by the interplanetary shock, and either energization to cause the enhancement, or lack of a seed population to cause the dropout.

Electromagnetic SAMPO monitoring soundings at Olkiluoto 2011 with updated interpretations

International Nuclear Information System (INIS)

Korhonen, K.

2013-11-01

The Geological Survey of Finland (GTK) has carried out electromagnetic depth soundings annually at fixed stations in Olkiluoto since 2004 as part of a monitoring programme. The goal of the programme is to detect and monitor changes in the electrical properties of the bedrock above and in the vicinity of the underground nuclear waste disposal facility. A new Sampo monitoring survey was carried out during September-October 2011. The survey resulted in 39 soundings at 17 measurement stations. The nominal coil separations of 200, 400, 500, 600 and 800 meters were used. Eight stations were selected for detailed annual layer-model interpretation. The layer models were based on prior geological and geophysical knowledge of the area. The thicknesses of the layer-model layers were kept fixed whereas their resistivities were solved for each subsequent year independent of each other. Many time series indicate clear trends in electrical resistivity. However, even though the data was carefully corrected and edited, the time series display a fairly large amount of variability increasing the uncertainty of the calculated trends. (orig.)

A review of nuclear geophysics

International Nuclear Information System (INIS)

Clayton, C.G.; Schweitzer, J.S.

1992-01-01

This paper summarizes the development of nuclear geophysics in scientific and technological content and in range from its beginnings early in this century to the present day. We note that the early work in nuclear geophysics was originally referred to under the umbrella of open-quotes isotope applicationsclose quotes and the origin of the term open-quotes nuclear geophysicsclose quotes (which is seen to clarify and to focus work in this area) is exposed in this paper. The current expansion of nuclear geophysics front its original concern with oil well logging is an important trend because much of the underlying science, technology, and instrumentation is common ground. A review of nuclear geophysics would be a barren document without reference to long-term and, in some cases, short-term commercial and economic as well as to technological considerations, since these factors are the principal motivation for further development

Echo in a semibounded plasma confined by an inhomogeneous electrostatic potential

International Nuclear Information System (INIS)

Revenchuk, S.M.

1997-01-01

The effect of the shape of a confining potential (potential barrier) on linear and nonlinear echoes arising due to the reflection of charged particles by this potential is studied. The model of a plasma confined by a potential that is a monotonous power-law function of the space coordinate is used to study the problem. It is shown that a linear echo (the effect of a nonlocal reflection of waves) arises only for a square-law confining potential. The second-order nonlinear echo caused by two external perturbations with different frequencies can occur for potentials with both square-law and inverse power-law coordinate dependences: the frequency of this echo equals the difference of the frequencies of the externally applied perturbations. In the model considered, an echo at the frequency that is the sum of the frequencies of the external perturbations, which was predicted in the previous papers, does not occur

Numerical modelling of so-called secondary ultrasonic echoes

International Nuclear Information System (INIS)

Langenberg, K.J.; Fellinger, P.; Hofmann, C.

1994-01-01

The formation of secondary ultrasonic echoes is discussed for a particularly simple testing situation. This discussion is based upon the intuitive visualization of elastic wave propagation as obtained with the numerical EFIT-Code (Elastodynamic Finite Integration Technique). The resulting travel times for the econdary echoes contain well-defined limits as they originate from the simple model of grazing incidence plane longitudinal wave mode conversion. (orig.) [de

Cardiac T2-mapping using a fast gradient echo spin echo sequence - first in vitro and in vivo experience

OpenAIRE

Baessler, Bettina; Schaarschmidt, Frank; Stehning, Christian; Schnackenburg, Bernhard; Maintz, David; Bunck, Alexander C.

2015-01-01

Background: The aim of this study was the evaluation of a fast Gradient Spin Echo Technique (GraSE) for cardiac T2-mapping, combining a robust estimation of T2 relaxation times with short acquisition times. The sequence was compared against two previously introduced T2-mapping techniques in a phantom and in vivo. Methods: Phantom experiments were performed at 1.5 T using a commercially available cylindrical gel phantom. Three different T2-mapping techniques were compared: a Multi Echo Spin Ec...

Detection of generalized synchronization using echo state networks

Science.gov (United States)

Ibáñez-Soria, D.; Garcia-Ojalvo, J.; Soria-Frisch, A.; Ruffini, G.

2018-03-01

Generalized synchronization between coupled dynamical systems is a phenomenon of relevance in applications that range from secure communications to physiological modelling. Here, we test the capabilities of reservoir computing and, in particular, echo state networks for the detection of generalized synchronization. A nonlinear dynamical system consisting of two coupled Rössler chaotic attractors is used to generate temporal series consisting of time-locked generalized synchronized sequences interleaved with unsynchronized ones. Correctly tuned, echo state networks are able to efficiently discriminate between unsynchronized and synchronized sequences even in the presence of relatively high levels of noise. Compared to other state-of-the-art techniques of synchronization detection, the online capabilities of the proposed Echo State Network based methodology make it a promising choice for real-time applications aiming to monitor dynamical synchronization changes in continuous signals.

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.

Science.gov (United States)

2010-04-01

... system. (a) Identification. An ultrasonic pulsed echo imaging system is a device intended to project a... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultrasonic pulsed echo imaging system. 892.1560... receiver. This generic type of device may include signal analysis and display equipment, patient and...

Diuretic-enhanced gadolinium excretory MR urography: comparison of conventional gradient-echo sequences and echo-planar imaging

Energy Technology Data Exchange (ETDEWEB)

Nolte-Ernsting, C.C.A.; Tacke, J.; Adam, G.B.; Haage, P.; Guenther, R.W. [Univ. of Technology, Aachen (Germany). Dept. of Diagnostic Radiology; Jung, P.; Jakse, G. [Univ. of Technology, Aachen (Germany). Dept. of Urology

2001-01-01

The aim of this study was to investigate the utility of different gadolinium-enhanced T1-weighted gradient-echo techniques in excretory MR urography. In 74 urologic patients, excretory MR urography was performed using various T1-weighted gradient-echo (GRE) sequences after injection of gadolinium-DTPA and low-dose furosemide. The examinations included conventional GRE sequences and echo-planar imaging (GRE EPI), both obtained with 3D data sets and 2D projection images. Breath-hold acquisition was used primarily. In 20 of 74 examinations, we compared breath-hold imaging with respiratory gating. Breath-hold imaging was significantly superior to respiratory gating for the visualization of pelvicaliceal systems, but not for the ureters. Complete MR urograms were obtained within 14-20 s using 3D GRE EPI sequences and in 20-30 s with conventional 3D GRE sequences. Ghost artefacts caused by ureteral peristalsis often occurred with conventional 3D GRE imaging and were almost completely suppressed in EPI sequences (p < 0.0001). Susceptibility effects were more pronounced on GRE EPI MR urograms and calculi measured 0.8-21.7% greater in diameter compared with conventional GRE sequences. Increased spatial resolution degraded the image quality only in GRE-EPI urograms. (orig.)

A new technique for MR elastography of the supraspinatus muscle: A gradient-echo type multi-echo sequence.

Science.gov (United States)

Ito, Daiki; Numano, Tomokazu; Mizuhara, Kazuyuki; Takamoto, Koichi; Onishi, Takaaki; Nishijo, Hisao

2016-10-01

Magnetic resonance elastography (MRE) can measure tissue stiffness quantitatively and noninvasively. Supraspinatus muscle injury is a significant problem among throwing athletes. The purpose of this study was to develop an MRE technique for application to the supraspinatus muscle by using a conventional magnetic resonance imaging (MRI). MRE acquisitions were performed with a gradient-echo type multi-echo MR sequence at 100Hz pneumatic vibration. A custom-designed vibration pad was used as a pneumatic transducer in order to adapt to individual shoulder shapes. In a gradient-echo type multi-echo MR sequence, without motion encoding gradient (MEG) that synchronizes with vibrations, bipolar readout gradient lobes achieved a similar function to MEG (MEG-like effect). In other words, a dedicated MRE sequence (built-in MEG) is not always necessary for MRE. In this study, 7 healthy volunteers underwent MRE. We investigated the effects of direction of the MEG-like effect and selected imaging planes on the patterns of wave propagation (wave image). The results indicated that wave images showed clear wave propagation on a condition that the direction of the MEG-like effect was nearly perpendicular to the long axis of the supraspinatus muscle, and that the imaging plane was superior to the proximal supraspinatus muscle. This limited condition might be ascribed to specific features of fibers in the supraspinatus muscle and wave reflection from the boundaries of the supraspinous fossa. The mean stiffness of the supraspinatus muscle was 10.6±3.17kPa. Our results demonstrated that using MRE, our method can be applied to the supraspinatus muscle by using conventional MRI. Copyright © 2016 Elsevier Inc. All rights reserved.

Spontaneous cerebral microbleeds on gradient echo MR imaging in the stroke patients

International Nuclear Information System (INIS)

Kwak, Seong Ho; Song, Chang June; Kim, Dae Bong; Jeong, Geum Chae

2003-01-01

To investigate the spontaneous cerebral microbleeding occurring at gradient-echo MRI, and its relationship with associated stroke lesions and risk factors. Between September 2001 and December, 2002, 32 patients (21 men and 11 women; mean age 63 years) in whom cerebral microbleeding occurred at gradient-echo MRI were retrospectively investigated. Using a 1.5T MR imager, spin-echo T1-weighted, fast spin-echo T2-weighted, diffusion-weighted, and gradient-echo images were obtained. The number and location of microbleeds seen on gradient echo images, patients data, and associated stroke lesions such as intracerebral hemorrhage and lacunar and territorial infarction were assessed. Among the 32 patients, 563 microbleeds and between 1 and 66 (mean, 17.6) were noted at gradient-echo imaging. Microbleeding occurred in the cortical/subcortical area (n=216), the basal ganglia (n=173), thalamus (n=92), cerebellum (n=41), brainstem (n=36) and corpus callosum (n=1), and in 20 patients was bilateral. Patients had a history of hypertension (n=26), hypertriglycemia (n=12), heart disease (n=4), and diabetes mellitus (n=3). Stroke lesions were seen in 27 patients, intracerebral hemorrhage in ten, lacunar infarction in 24, and territorial infarction in four. The incidence and number of microbleeds was greater in older patients and in those with hypertension, hypertriglycemia, and stroke lesions such as intracerebral hemorrhage or lacunar infarction. The detection of microbleeding at gradient-echo imaging is helpful, since it predicts the possibility of cerebral hemorrhage in these patients

Proton T2 Relaxation effect of superparamagnetic iron oxide on fast spin echo sequence. Influence of echo number (even or odd) of effective TE

International Nuclear Information System (INIS)

Tsuchihashi, Toshio; Maki, Toshio; Kitagawa, Matsuo; Suzuki, Takeshi; Fujita, Isao

1999-01-01

The T 2 relaxation effect of the fast spin echo sequence (FSE) was investigated using superparamagnetic iron oxide (SPIO) particles. When even echoes were used as the effective TE of FSE, the signal intensity ratio [signal intensity of FSE/signal intensity of conventional spin echo sequence (CSE)] of FSE and CSE increased, whereas the T 2 relaxation effect of SPIO with FSE was reduced. However, when odd echoes were used, neither signal intensity changed, and weakening of the T 2 relaxation effect, considered a problem with FSE, was reduced. This phenomenon was not observed when the refocusing flip angle was changed to 30 and 60 degrees. However, it was observed when the refocusing flip angle was 120 and 150 degrees. Thus, this phenomenon can be considered to be related to oscillation in longitudinal magnetization when using the Carr-Purcell-Meiboom-Gill (CPMG) technique. (author)

The Absent Presence of the Parental Generation: Incest and the Ordering of Experience in The Sound and The Fury

Science.gov (United States)

1993-04-25

Father and son are secret sharers in defeat, and the argument between them echoed in the second section suggests not so much a duel as a doleful...in a duel . Failing in all five parts of Wyatt-Brown’s definition of honorable conduct, Quentin shamefully relives the act in many forms throughout his... Psychoanalysis . 3 (1975): 151-62. Bleikasten, Andre. The Ink of Melancholy: Faulkner’s Novels from The Sound and the Fury to Light in August. Bloom- ington

Water Quality Indicators Data Review | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Civil Enforcement Case Report Data Dictionary | ECHO | US ...

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Water Pollution Search Criteria Help | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

DW_Dashboard_CalendarView.png | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

TRI DMR Dashboard Top Industries_Chemicals.png | ECHO ...

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Hypoxia Task Force Scope and Methodology | ECHO | US ...

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

HF Radar Sea-echo from Shallow Water

Directory of Open Access Journals (Sweden)

Josh Kohut

2008-08-01

Full Text Available HF radar systems are widely and routinely used for the measurement of ocean surface currents and waves. Analysis methods presently in use are based on the assumption of infinite water depth, and may therefore be inadequate close to shore where the radar echo is strongest. In this paper, we treat the situation when the radar echo is returned from ocean waves that interact with the ocean floor. Simulations are described which demonstrate the effect of shallow water on radar sea-echo. These are used to investigate limits on the existing theory and to define water depths at which shallow-water effects become significant. The second-order spectral energy increases relative to the first-order as the water depth decreases, resulting in spectral saturation when the waveheight exceeds a limit defined by the radar transmit frequency. This effect is particularly marked for lower radar transmit frequencies. The saturation limit on waveheight is less for shallow water. Shallow water affects second-order spectra (which gives wave information far more than first-order (which gives information on current velocities, the latter being significantly affected only for the lowest radar transmit frequencies for extremely shallow water. We describe analysis of radar echo from shallow water measured by a Rutgers University HF radar system to give ocean wave spectral estimates. Radar-derived wave height, period and direction are compared with simultaneous shallow-water in-situ measurements.

HST Archival Imaging of the Light Echoes of SN 1987A

Science.gov (United States)

Lawrence, S. S.; Hayon, M.; Sugerman, B. E. K.; Crotts, A. P. S.

2002-12-01

We have undertaken a search for light echo signals from Supernova 1987A that have been serendipitously recorded in images taken near the 30 Doradus region of the Large Magellanic Cloud by HST. We used the MAST interface to create a database of the 1282 WF/PC, WFPC2 and STIS images taken within 15 arcminutes of the supernova, between 1992 April and 2002 June. These 1282 images are grouped into 125 distinct epochs and pointings, with each epoch containing between 1 and 42 separate exposures. Sorting this database with various programs, aided by the STScI Visual Target Tuner, we have identified 63 pairs of WFPC2 imaging epochs that are not centered on the supernova but that have a significant amount of spatial overlap between their fields of view. These image data were downloaded from the public archive, cleaned of cosmic rays, and blinked to search for light echoes at radii larger than 2 arcminutes from the supernova. Our search to date has focused on those pairs of epochs with the largest degree of overlap. Of 16 pairs of epochs scanned to date, we have detected 3 strong light echoes and one faint, tentative echo signal. We will present direct and difference images of these and any further echoes, as well as the 3-D geometric, photometric and color properties of the echoing dust structures. In addition, a set of 20 epochs of WF/PC and WFPC2 imaging centered on SN 1987A remain to be searched for echoes within 2 arcminutes of the supernova. We will discuss our plans to integrate the high spatial-resolution HST snapshots of the echoes with our extensive, well-time-sampled, ground-based imaging data. We gratefully acknowledge the support of this undergraduate research project through an HST Archival Research Grant (HST-AR-09209.01-A).

Influence of sound source location on the behavior and physiology of the precedence effect in cats.

Science.gov (United States)

Dent, Micheal L; Tollin, Daniel J; Yin, Tom C T

2009-08-01

Psychophysical experiments on the precedence effect (PE) in cats have shown that they localize pairs of auditory stimuli presented from different locations in space based on the spatial position of the stimuli and the interstimulus delay (ISD) between the stimuli in a manner similar to humans. Cats exhibit localization dominance for pairs of transient stimuli with |ISDs| from approximately 0.4 to 10 ms, summing localization for |ISDs| 10 ms, which is the approximate echo threshold. The neural correlates to the PE have been described in both anesthetized and unanesthetized animals at many levels from auditory nerve to cortex. Single-unit recordings from the inferior colliculus (IC) and auditory cortex of cats demonstrate that neurons respond to both lead and lag sounds at ISDs above behavioral echo thresholds, but the response to the lag is reduced at shorter ISDs, consistent with localization dominance. Here the influence of the relative locations of the leading and lagging sources on the PE was measured behaviorally in a psychophysical task and physiologically in the IC of awake behaving cats. At all configurations of lead-lag stimulus locations, the cats behaviorally exhibited summing localization, localization dominance, and breakdown of fusion. Recordings from the IC of awake behaving cats show neural responses paralleling behavioral measurements. Both behavioral and physiological results suggest systematically shorter echo thresholds when stimuli are further apart in space.

Collision-induced stimulated photon echoes in ‘strong’ magnetic field

Science.gov (United States)

Reshetov, V. A.

2018-05-01

Collision-induced stimulated photon echoes formed in a gaseous medium on the transition with the angular momentum change Ja=0 → Jb=1 under the action of ‘strong’ longitudinal magnetic field, when the echo pulse becomes unpolarized, are considered with an account of elastic depolarizing collisions. In the case of narrow spectral line the explicit expressions for the echo polarization density matrix and the degree of polarization are obtained. In the case of broad spectral line the results of the numeric calculations reproduce qualitatively the curve obtained in the experiments with ytterbium vapor.

Sound

CERN Document Server

Robertson, William C

2003-01-01

Muddled about what makes music? Stuck on the study of harmonics? Dumbfounded by how sound gets around? Now you no longer have to struggle to teach concepts you really don t grasp yourself. Sound takes an intentionally light touch to help out all those adults science teachers, parents wanting to help with homework, home-schoolers seeking necessary scientific background to teach middle school physics with confidence. The book introduces sound waves and uses that model to explain sound-related occurrences. Starting with the basics of what causes sound and how it travels, you'll learn how musical instruments work, how sound waves add and subtract, how the human ear works, and even why you can sound like a Munchkin when you inhale helium. Sound is the fourth book in the award-winning Stop Faking It! Series, published by NSTA Press. Like the other popular volumes, it is written by irreverent educator Bill Robertson, who offers this Sound recommendation: One of the coolest activities is whacking a spinning metal rod...

Neogene and Quaternary geology of a stratigraphic test hole on Horn Island, Mississippi Sound

Science.gov (United States)

Gohn, Gregory S.; Brewster-Wingard, G. Lynn; Cronin, Thomas M.; Edwards, Lucy E.; Gibson, Thomas G.; Rubin, Meyer; Willard, Debra A.

1996-01-01

During April and May, 1991, the U.S. Geological Survey (USGS) drilled a 510-ft-deep, continuously cored, stratigraphic test hole on Horn Island, Mississippi Sound, as part of a field study of the Neogene and Quaternary geology of the Mississippi coastal area. The USGS drilled two new holes at the Horn Island site. The first hole was continuously cored to a depth of 510 ft; coring stopped at this depth due to mechanical problems. To facilitate geophysical logging, an unsampled second hole was drilled to a depth of 519 ft at the same location.

Monitoring of aquifer pump tests with Magnetic Resonance Sounding (MRS): a synthetic case study

DEFF Research Database (Denmark)

Herckenrath, Daan; Auken, E.; Bauer-Gottwein, Peter

2011-01-01

Magnetic Resonance Sounding (MRS) can provide valuable data to constrain and calibrate groundwater flow and transport models. With this non-invasive geophysical technique, measurements of water content and hydraulic conductivity can be obtained. We developed a hydrogeophyiscal forward method, which...... calculates the MRS-signal generated by an aquifer pump test. A synthetic MRS-dataset was subsequently used to determine the hydrogeological parameters in an inverse parameter estimation approach. This was done for a virtual pump test with a partially and a fully penetrating well. With the MRS data we were...

Improved sensitivity and specificity for resting state and task fMRI with multiband multi-echo EPI compared to multi-echo EPI at 7T.

NARCIS (Netherlands)

Boyacioglu, R.; Schulz, J.; Koopmans, P.J.; Barth, M.; Norris, David Gordon

2015-01-01

A multiband multi-echo (MBME) sequence is implemented and compared to a matched standard multi-echo (ME) protocol to investigate the potential improvement in sensitivity and spatial specificity at 7 T for resting state and task fMRI. ME acquisition is attractive because BOLD sensitivity is less

A review of geophysical investigations at the site of Chalk River Nuclear Laboratories, Ontario

International Nuclear Information System (INIS)

Thomas, M.D.; Hayles, J.G.

1988-01-01

The site of the Chalk River Nuclear Laboratories was one of the first research areas located on crystalline rocks to be extensively investigated under the Canadian Nuclear Fuel Waste Management Program. A large contribution to meeting the geoscientific objectives of the program has been made using a suite of geophysical techniques. Many of them are standard, though sometimes modified in terms of instrumentation and/or experimental and/or analytical procedures, to meet the particular needs of the waste management program. Relatively new techniques have also been employed. Much of the early evaluation and development of the various techniques took place at the Chalk River site. Standard methods such as gravity, magnetics and seismic sounding have been used to investigate bedrock structure, and the seismic method has also been used to estimate overburden thickness. Standard geophysical borehole logging has been used to obtain in situ estimates of physical properties, to locate fracture zones and to make hole to hole correlations that have helped define local structure. Several standard electrical (e.g. resitivity) and electromagnetic (e.g. VLF-EM) techniques have proven successful in identifying water-filled fractures and faults. Relatively new techniques introduced into the geophysics at Chalk River were: ground probing radar; to investigate overburden; borehole TV and acoustic televiewer and VLF-EM, to locate fractures; studies of seismic tube-waves, well tides and temperature logs, to investigate fracture location and permeability. Most of these methods have been successful and are now routinely employed at other research sites

ECHO Services: Foundational Middleware for a Science Cyberinfrastructure

Science.gov (United States)

Burnett, Michael

2005-01-01

This viewgraph presentation describes ECHO, an interoperability middleware solution. It uses open, XML-based APIs, and supports net-centric architectures and solutions. ECHO has a set of interoperable registries for both data (metadata) and services, and provides user accounts and a common infrastructure for the registries. It is built upon a layered architecture with extensible infrastructure for supporting community unique protocols. It has been operational since November, 2002 and it available as open source.

A fractured rock geophysical toolbox method selection tool

Science.gov (United States)

Day-Lewis, F. D.; Johnson, C.D.; Slater, L.D.; Robinson, J.L.; Williams, J.H.; Boyden, C.L.; Werkema, D.D.; Lane, J.W.

2016-01-01

Geophysical technologies have the potential to improve site characterization and monitoring in fractured rock, but the appropriate and effective application of geophysics at a particular site strongly depends on project goals (e.g., identifying discrete fractures) and site characteristics (e.g., lithology). No method works at every site or for every goal. New approaches are needed to identify a set of geophysical methods appropriate to specific project goals and site conditions while considering budget constraints. To this end, we present the Excel-based Fractured-Rock Geophysical Toolbox Method Selection Tool (FRGT-MST). We envision the FRGT-MST (1) equipping remediation professionals with a tool to understand what is likely to be realistic and cost-effective when contracting geophysical services, and (2) reducing applications of geophysics with unrealistic objectives or where methods are likely to fail.

Informing groundwater models with near-surface geophysical data

DEFF Research Database (Denmark)

Herckenrath, Daan

Over the past decade geophysical methods have gained an increased popularity due to their ability to map hydrologic properties. Such data sets can provide valuable information to improve hydrologic models. Instead of using the measured geophysical and hydrologic data simultaneously in one inversion...... approach, many of the previous studies apply a Sequential Hydrogeophysical Inversion (SHI) in which inverted geophysical models provide information for hydrologic models. In order to fully exploit the information contained in geophysical datasets for hydrological purposes, a coupled hydrogeophysical...... inversion was introduced (CHI), in which a hydrologic model is part of the geophysical inversion. Current CHI-research has been focussing on the translation of simulated state variables of hydrologic models to geophysical model parameters. We refer to this methodology as CHI-S (State). In this thesis a new...

Experimental observation of fluid echoes in a non-neutral plasma

International Nuclear Information System (INIS)

Yu, Jonathan H.; Driscoll, C. Fred

2002-01-01

Experimental observation of a nonlinear fluid echo is presented which demonstrates the reversible nature of spatial Landau damping, and that non-neutral plasmas behave as nearly ideal 2D fluids. These experiments are performed on UCSD's CamV Penning-Malmberg trap with magnetized electron plasmas. An initial m i =2 diocotron wave is excited, and the received wall signal damps away in about 5 wave periods. The density perturbation filaments are observed to wrap up as the wave is spatially Landau damped. An m t =4 'tickler' wave is then excited, and this wave also Landau damps. The echo consists of a spontaneous appearance of a third m e =2 wave after the responses to the first two waves have inviscidly damped away. The appearance time of the echo agrees with theory, and data suggests the echo is destroyed at least partly due to saturation

Multiscale geophysical imaging of the critical zone

Science.gov (United States)

Parsekian, Andy; Singha, Kamini; Minsley, Burke J.; Holbrook, W. Steven; Slater, Lee

2015-01-01

Details of Earth's shallow subsurface—a key component of the critical zone (CZ)—are largely obscured because making direct observations with sufficient density to capture natural characteristic spatial variability in physical properties is difficult. Yet this inaccessible region of the CZ is fundamental to processes that support ecosystems, society, and the environment. Geophysical methods provide a means for remotely examining CZ form and function over length scales that span centimeters to kilometers. Here we present a review highlighting the application of geophysical methods to CZ science research questions. In particular, we consider the application of geophysical methods to map the geometry of structural features such as regolith thickness, lithological boundaries, permafrost extent, snow thickness, or shallow root zones. Combined with knowledge of structure, we discuss how geophysical observations are used to understand CZ processes. Fluxes between snow, surface water, and groundwater affect weathering, groundwater resources, and chemical and nutrient exports to rivers. The exchange of gas between soil and the atmosphere have been studied using geophysical methods in wetland areas. Indirect geophysical methods are a natural and necessary complement to direct observations obtained by drilling or field mapping. Direct measurements should be used to calibrate geophysical estimates, which can then be used to extrapolate interpretations over larger areas or to monitor changing processes over time. Advances in geophysical instrumentation and computational approaches for integrating different types of data have great potential to fill gaps in our understanding of the shallow subsurface portion of the CZ and should be integrated where possible in future CZ research.

Comparison of dynamic dual spin-echo and fast-gradient-echo techniques in the evaluation of cardiac diseases

International Nuclear Information System (INIS)

Pettigrew, R.I.; Eisner, R.L.; Groen, J.P.; Baron, M.G.

1987-01-01

To determine the relative roles of a dynamic spin-echo method and a fast acquisition with multiphase excitations (FAME) technique, ten patients with myocardial infarction (MI), five with myocardial masses, and five healthy patients were studied with both methods. The dynamic dual-spin-echo (DSE) technique allows acquisition of each of seven sections at 14 cardiac phases in 20 minutes. Wall motion abnormalities were seen equally well with both techniques, but FAME usually required a shorter study time (10 minutes). DSE, however, was superior for evaluating cardiac masses and provided superior wall blood contrast. Thus, these techniques are complementary, and both are now a routine part of the authors' study of cardiac patients

Usefulness of dual echo volumetric isotropic turbo spin echo acquisition (VISTA) in MR imaging of the temporomandibular joint

International Nuclear Information System (INIS)

Sugimori, Yuko; Tanaka, Shigeko; Naito, Yukari; Nishimura, Tetsuya; Yamamoto, Akira; Miki, Yukio; Ohfuji, Satoko; Katsumata, Yasutomo

2013-01-01

We investigated the ability to detect the articular disk and joint effusion of the temporomandibular joint (TMJ) of a method of dual echo volumetric isotropic turbo spin echo acquisition (DE-VISTA) additional fusion images (AFI). DE-VISTA was performed in the 26 TMJ of 13 volunteers and 26 TMJ of 13 patients. Two-dimensional (2D) dual echo turbo spin echo was performed in the 26 TMJ of 13 volunteers. On a workstation, we added proton density-weighted images (PDWI) and T 2 weighted images (T 2 WI) of the DE-VISTA per voxel to reconstruct DE-VISTA-AFI. Two radiologists reviewed these images visually and quantitatively. Visual evaluation of the articular disk was equivalent between DE-VISTA-AFI and 2D-PDWI. The sliding thin-slab multiplanar reformation (MPR) method of DE-VISTA-AFI could detect all articular disks. The ratio of contrast (CR) of adipose tissue by the articular disk to that of the articular disk itself was significantly higher in DE-VISTA-AFI than DE-VISTA-PDWI (P 2 WI but in only 3 of those joints in 2D-T 2 WI. The CR of joint effusion to adipose tissue on DE-VISTA-AFI did not differ significantly from that on DE-VISTA-PDWI. However, using DE-VISTA-T 2 WI in addition to DE-VISTA-PDWI, we could visually identify joint effusion on DE-VISTA-AFI that could not be identified on DE-VISTA-PDWI alone. DE-VISTA-AFI can depict the articular disk and a small amount of joint effusion by the required plane of MPR using the sliding thin-slab MPR method. (author)

MARSIS data and simulation exploited using array databases: PlanetServer/EarthServer for sounding radars

Science.gov (United States)

Cantini, Federico; Pio Rossi, Angelo; Orosei, Roberto; Baumann, Peter; Misev, Dimitar; Oosthoek, Jelmer; Beccati, Alan; Campalani, Piero; Unnithan, Vikram

2014-05-01

MARSIS is an orbital synthetic aperture radar for both ionosphere and subsurface sounding on board ESA's Mars Express (Picardi et al. 2005). It transmits electromagnetic pulses centered at 1.8, 3, 4 or 5 MHz that penetrate below the surface and are reflected by compositional and/or structural discontinuities in the subsurface of Mars. MARSIS data are available as a collection of single orbit data files. The availability of tools for a more effective access to such data would greatly ease data analysis and exploitation by the community of users. For this purpose, we are developing a database built on the raster database management system RasDaMan (e.g. Baumann et al., 1994), to be populated with MARSIS data and integrated in the PlanetServer/EarthServer (e.g. Oosthoek et al., 2013; Rossi et al., this meeting) project. The data (and related metadata) are stored in the db for each frequency used by MARSIS radar. The capability of retrieving data belonging to a certain orbit or to multiple orbit on the base of latitute/longitude boundaries is a key requirement of the db design, allowing, besides the "classical" radargram representation of the data, and in area with sufficiently hight orbit density, a 3D data extraction, subset and analysis of subsurface structures. Moreover the use of the OGC WCPS (Web Coverage Processing Service) standard can allow calculations on database query results for multiple echoes and/or subsets of a certain data product. Because of the low directivity of its dipole antenna, MARSIS receives echoes from portions of the surface of Mars that are distant from nadir and can be mistakenly interpreted as subsurface echoes. For this reason, methods have been developed to simulate surface echoes (e.g. Nouvel et al., 2004), to reveal the true origin of an echo through comparison with instrument data. These simulations are usually time-consuming, and so far have been performed either on a case-by-case basis or in some simplified form. A code for

Zonal asymmetry of daytime 150-km echoes observed by Equatorial Atmosphere Radar in Indonesia

Directory of Open Access Journals (Sweden)

T. Yokoyama

2009-03-01

Full Text Available Multi-beam observations of the daytime ionospheric E-region irregularities and the so-called 150-km echoes with the 47-MHz Equatorial Atmosphere Radar (EAR in West Sumatra, Indonesia (0.20° S, 100.32° E, 10.36° S dip latitude are presented. 150-km echoes have been frequently observed by the EAR, and their characteristics are basically the same as the equatorial ones, except for an intriguing zonal asymmetry; stronger echoes in lower altitudes in the east directions, and weaker echoes in higher altitudes in the west. The highest occurrence is seen at 5.7° east with respect to the magnetic meridian, and the altitude gradually increases as viewing from the east to west. Arc structures which return backscatter echoes are proposed to explain the asymmetry. While the strength of radar echoes below 105 km is uniform within the wide coverage of azimuthal directions, the upper E-region (105–120 km echoes also show a different type of zonal asymmetry, which should be generated by an essentially different mechanism from the lower E-region and 150-km echoes.

2D interpretation of vertical electrical soundings: application to the Sarantaporon basin (Thessaly, Greece)

International Nuclear Information System (INIS)

Atzemoglou, A; Tsourlos, P

2012-01-01

A large-scale vertical electrical sounding (VES) survey was applied at the basin of Sarantaporon, Elassona in order to study the tectonic and hydrogeological setting of the area. A large number of VES was obtained on a near-regular grid and data were initially processed with 1D inversion algorithm. Since some of the dense measured soundings were collinear, it was possible to combine 1D sounding data and produce 2D data sets which were interpreted using a fully 2D inversion algorithm. 2D geoelectrical models were in very good agreement with the existing drilling information of the area. 2D interpretation results were combined to produce pseudo-3D geoelectrical images of the subsurface. Resulting geoelectrical interpretations are in very good agreement with the existing geological information and reveal a relatively detailed picture of the basin's lithology. Further, the results allowed us to obtain new, and verify existing, structural information regarding the studied area. Overall, it is concluded that 2D interpretation of 1D VES measurements can produce improved subsurface geophysical images and presents a potential useful tool for larger scale geological investigations especially in the case of reprocessing existing VES data sets

Bias-Voltage Stabilizer for HVHF Amplifiers in VHF Pulse-Echo Measurement Systems.

Science.gov (United States)

Choi, Hojong; Park, Chulwoo; Kim, Jungsuk; Jung, Hayong

2017-10-23

The impact of high-voltage-high-frequency (HVHF) amplifiers on echo-signal quality is greater with very-high-frequency (VHF, ≥100 MHz) ultrasound transducers than with low-frequency (LF, ≤15 MHz) ultrasound transducers. Hence, the bias voltage of an HVHF amplifier must be stabilized to ensure stable echo-signal amplitudes. We propose a bias-voltage stabilizer circuit to maintain stable DC voltages over a wide input range, thus reducing the harmonic-distortion components of the echo signals in VHF pulse-echo measurement systems. To confirm the feasibility of the bias-voltage stabilizer, we measured and compared the deviations in the gain of the HVHF amplifier with and without a bias-voltage stabilizer. Between -13 and 26 dBm, the measured gain deviations of a HVHF amplifier with a bias-voltage stabilizer are less than that of an amplifier without a bias-voltage stabilizer. In order to confirm the feasibility of the bias-voltage stabilizer, we compared the pulse-echo responses of the amplifiers, which are typically used for the evaluation of transducers or electronic components used in pulse-echo measurement systems. From the responses, we observed that the amplitudes of the echo signals of a VHF transducer triggered by the HVHF amplifier with a bias-voltage stabilizer were higher than those of the transducer triggered by the HVHF amplifier alone. The second, third, and fourth harmonic-distortion components of the HVHF amplifier with the bias-voltage stabilizer were also lower than those of the HVHF amplifier alone. Hence, the proposed scheme is a promising method for stabilizing the bias voltage of an HVHF amplifier, and improving the echo-signal quality of VHF transducers.

Workshop on neutron spin-echo

Energy Technology Data Exchange (ETDEWEB)

Aynajian, P.; Habicht, K.; Keller, Th.; Keimer, B.; Mezei, F.; Monkenbusch, M.; Allgaier, J.; Richter, D.; Fetters, L.J.; Muller, K.; Kreiling, S.; Dehnicke, K.; Greiner, A.; Ehlers, G.; Arbe, A.; Colmenero, J.; Richter, D.; Farago, B.; Monkenbusch, M.; Ohl, M.; Butzek, M.; Kozielewski, T.; Monkenbusch, M.; Richter, D.; Pappas, C.; Hillier, A.; Manuel, P.; Cywinski, R.; Bentley, P.; Alba, M.; Mezei, F.; Campbell, I.A.; Zimmermann, U.; Ellis, J.; Jobic, H.; Pickup, R.M.; Pappas, C.; Farago, B.; Cywinski, R.; Haussler, W.; Holderer, O.; Frielinghaus, H.; Byelov, D.; Monkenbusch, M.; Allgaier, J.; Richter, D.; Egger, H.; Hellweg, Th.; Malikova, N.; Cadene, A.; Marry, V.; Dubois, E.; Turq, P.; Gardner, J.S.; Ehlers, G.; Bramwell, St.S.; Grigoriev, S.; Kraan, W.; Rekveldt, T.; Bouwman, W.; Van Dijk, N.; Falus, P.; Vorobiev, A.; Major, J.; Felcher, G.P.; Te-velthuis, S.; Dosch, H.; Vorobiev, A.; Dridi, M.H.; Major, J.; Dosch, H.; Falus, P.; Felcher, G.P.; Te Velthuis, S.G.E.; Bleuel, M.; Broell, M.; Lang, E.; Littrell, K.; Gahler, R.; Lal, J.; Lauter, H.; Toperverg, B.; Lauter, V.; Jernenkov, M.; Stueber, S.; Enderle, M.; Janoschek, M.; Keller, Th.; Klimko, S.; Boeni, P.; Nagao, M.; Yamada, N.; Kawabata, Y.; Seto, H.; Takeda, T.; Yoshizawa, H.; Yoshida, K.; Yamaguchi, T.; Bellissent-Funel, M.C.; Longeville, St

2005-07-01

This document gathers the abstracts of most papers presented at the workshop. Neutron spin-echo (NSE) spectroscopy is a well established technique with a growing expert user community, the aim of the meeting was to discuss the latest achievements in neutron spin-echo science and instrumentation. One of the applications presented is the investigation on the microscopic scale of the dynamics of water in montmorillonite clays with Na{sup +} and Cs{sup +} ions in monolayer and bilayer states. The NSE technique has been used in the normal and resonance modes. NSE results show consistently slower dynamics (higher relaxation times) than both time-of-flight technique (TOF) and classical molecular dynamics simulations (MD). In the present TOF and NSE experiments, anisotropy of the water motion in the interlayer is almost impossible to detect, due to the use of powder samples and insufficient resolution. (A.C.)

Study of turbulent flow using Half-Fourier Echo-Planar imaging

International Nuclear Information System (INIS)

Rodriguez, A.O.

2006-01-01

The Echo-Planar Imaging technique combined with a partial Fourier acquisition method was used to obtain velocity images for liquid flows in a circular cross-section pipe at Reynolds number of up to 8000. This partial-Fourier imaging scheme is able to generate shorter echo times than the full-Fourier Echo-Planar Imaging methods, reducing the signal attenuation due to T2 * and flow. Velocity images along the z axis were acquired with a time-scale of 80 ms thus obtaining a real-time description of flow in both the laminar and turbulent regimes. Velocity values and velocity fluctuations were computed with the flow image data. A comparison plot of NMR velocity and bulk velocity and a plot of velocity fluctuations were calculated to investigate the feasibility of this imaging technique. Flow encoded Echo-Planar Imaging together with a reduced data acquisition method can provide us with a real-time technique to capture instantaneous images of the flow field for both laminar and turbulent regimes. (author)

Methodological Developments in Geophysical Assimilation Modeling

Science.gov (United States)

Christakos, George

2005-06-01

This work presents recent methodological developments in geophysical assimilation research. We revisit the meaning of the term "solution" of a mathematical model representing a geophysical system, and we examine its operational formulations. We argue that an assimilation solution based on epistemic cognition (which assumes that the model describes incomplete knowledge about nature and focuses on conceptual mechanisms of scientific thinking) could lead to more realistic representations of the geophysical situation than a conventional ontologic assimilation solution (which assumes that the model describes nature as is and focuses on form manipulations). Conceptually, the two approaches are fundamentally different. Unlike the reasoning structure of conventional assimilation modeling that is based mainly on ad hoc technical schemes, the epistemic cognition approach is based on teleologic criteria and stochastic adaptation principles. In this way some key ideas are introduced that could open new areas of geophysical assimilation to detailed understanding in an integrated manner. A knowledge synthesis framework can provide the rational means for assimilating a variety of knowledge bases (general and site specific) that are relevant to the geophysical system of interest. Epistemic cognition-based assimilation techniques can produce a realistic representation of the geophysical system, provide a rigorous assessment of the uncertainty sources, and generate informative predictions across space-time. The mathematics of epistemic assimilation involves a powerful and versatile spatiotemporal random field theory that imposes no restriction on the shape of the probability distributions or the form of the predictors (non-Gaussian distributions, multiple-point statistics, and nonlinear models are automatically incorporated) and accounts rigorously for the uncertainty features of the geophysical system. In the epistemic cognition context the assimilation concept may be used to

36 CFR 902.59 - Geological and geophysical information.

Science.gov (United States)

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Geological and geophysical information. 902.59 Section 902.59 Parks, Forests, and Public Property PENNSYLVANIA AVENUE DEVELOPMENT... Geological and geophysical information. Any geological or geophysical information and data (including maps...

Water Dashboard Help | ECHO | US EPA

Science.gov (United States)

The dashboards on the ECHO website are specialized to track both facility and agency performance as they relate to compliance with and enforcement of environmental standards under the Clean Water Act (CWA).

Climatology and variability in the ECHO coupled GCM

International Nuclear Information System (INIS)

Latif, M.; Stockdale, T.; Wolff, J.; Burgers, G.; Maier-Reimer, E.; Junge, M.M.; Arpe, K.; Bengtsson, L.

1993-01-01

ECHO is a new global coupled ocean-atmosphere general circulation model (GCM), consisting of the Hamburg version of the European Centre atmospheric GCM (ECHAM) and the Hamburg Primitive Equation ocean GCM (HOPE). We performed a twenty year integration with ECHO. Climate drift is significant, but typical in the open oceans. Near the boundaries, however, SST errors are considerably larger. The coupled model simulates an irregular ENSO cycle in the tropical Pacific, with spatial patterns similar to those observed. The mechanism behind the model ENSO is related to the subsurface memory of the system, but stochastic forcing by the atmosphere seems to be also important. The variability, however, is somewhat weaker relative to observations. ECHO also simulates significant interannual variability in midlatitudes. Consistent with observations, variability over the North Pacific can be partly attributed to remote forcing from the tropics. In contract, the interannual variability over the North Atlantic appears to be generated locally. Indications for decadal-scale variability are also found over the North Atlantic. (orig.)

Russian Meteorological and Geophysical Rockets of New Generation

Science.gov (United States)

Yushkov, V.; Gvozdev, Yu.; Lykov, A.; Shershakov, V.; Ivanov, V.; Pozin, A.; Afanasenkov, A.; Savenkov, Yu.; Kuznetsov, V.

2015-09-01

To study the process in the middle and upper atmosphere, ionosphere and near-Earth space, as well as to monitor the geophysical environment in Russian Federal Service for Hydrology and Environmental Monitoring (ROSHYDROMET) the development of new generation of meteorological and geophysical rockets has been completed. The modern geophysical research rocket system MR-30 was created in Research and Production Association RPA "Typhoon". The basis of the complex MR-30 is a new geophysical sounding rocket MN-300 with solid propellant, Rocket launch takes place at an angle of 70º to 90º from the launcher, which is a farm with a guide rail type required for imparting initial rotation rocket. The Rocket is spin stabilized with a spin rate between 5 and 7 Hz. Launch weight is 1564 kg, and the mass of the payload of 50 to 150 kg. MR-300 is capable of lifting up to 300 km, while the area of dispersion points for booster falling is an ellipse with parameters 37x 60 km. The payload of the rocket MN-300 consists of two sections: a sealed, located below the instrument compartment, and not sealed, under the fairing. Block of scientific equipment is formed on the platform in a modular layout. This makes it possible to solve a wide range of tasks and conduct research and testing technologies using a unique environment of space, as well as to conduct technological experiments testing and research systems and spacecraft equipment. New Russian rocket system MERA (MEteorological Rocket for Atmospheric Research) belongs to so called "dart" technique that provide lifting of small scientific payload up to altitude 100 km and descending with parachute. It was developed at Central Aerological Observatory jointly with State Unitary Enterprise Instrument Design Bureau. The booster provides a very rapid acceleration to about Mach 5. After the burning phase of the buster the dart is separated and continues ballistic flight for about 2 minutes. The dart carries the instrument payload+ parachute

25 CFR 211.56 - Geological and geophysical permits.

Science.gov (United States)

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Geological and geophysical permits. 211.56 Section 211.56... FOR MINERAL DEVELOPMENT Rents, Royalties, Cancellations and Appeals § 211.56 Geological and geophysical permits. Permits to conduct geological and geophysical operations on Indian lands which do not...

Two-pulse and stimulated nuclear-quadrupole-resonance echoes in YAlO3:Pr3+

International Nuclear Information System (INIS)

Erickson, L.E.

1991-01-01

The dephasing of trivalent praseodymium dilute in yttrium aluminum oxide (YAlO 3 ) in the ground electronic state 3 H 4 state is evaluated using an optically detected method, to measure two-rf-pulse- and three-rf-pulse-stimulated nuclear quadrupole echoes. The magnitude of the echo is obtained by detecting the weak Raman optical field generated by the interaction of the magnetic moment of the echo and a light beam resonant with the 3 H 4 (0 cm 1 ) to 1 D 2 (16 374 cm -1 ) optical transition. This same light beam is used as an optical pump (37-ms duration) prior the rf-pulse sequence to increase the population difference of the hyperfine energy levels, thereby improving the echo signal. The light is turned off 9 ms before the rf-pulse sequence and remains off until the echo to avoid optical-pumping effects on the measured nuclear-quadrupole-resonance (NQR) echo lifetime. The dephasing time T 2 from two-pulse nuclear-quadrupole-echo measurement is found to be 366±29 μs

Mapping of sound scattering objects in the northern part of the Barents Sea and their geological interpretation

Science.gov (United States)

Sokolov, S. Yu.; Moroz, E. A.; Abramova, A. S.; Zarayskaya, Yu. A.; Dobrolubova, K. O.

2017-07-01

On cruises 25 (2007) and 28 (2011) of the R/V Akademik Nikolai Strakhov in the northern part of the Barents Sea, the Geological Institute, Russian Academy of Sciences, conducted comprehensive research on the bottom relief and upper part of the sedimentary cover profile under the auspices of the International Polar Year program. One of the instrument components was the SeaBat 8111 shallow-water multibeam echo sounder, which can map the acoustic field similarly to a side scan sonar, which records the response both from the bottom and from the water column. In the operations area, intense sound scattering objects produced by the discharge of deep fluid flows are detected in the water column. The sound scattering objects and pockmarks in the bottom relief are related to anomalies in hydrocarbon gas concentrations in bottom sediments. The sound scattering objects are localized over Triassic sequences outcropping from the bottom. The most intense degassing processes manifest themselves near the contact of the Triassic sequences and Jurassic clay deposits, as well as over deep depressions in a field of Bouguer anomalies related to the basement of the Jurassic-Cretaceous rift system

A spin echo study of A15 intermetallic compounds

International Nuclear Information System (INIS)

Schoep, G.K.

1976-01-01

This thesis mainly concerns the measurement of spin-lattice relaxation times in intermetallic compounds of the bcc lattice structure, having the formula V 3 X (C = Pt, Ir, Os, Pd, Rh, Ni, Co, Au). When, in a spin echo experiment, a two-pulse sequence was applied, several quadrupolar echoes were observed. Special attention is given to the 'forbidden' echoes (absol.(Δm')GT1) in V 3 Au and V 3 Co. In relation to the V 3 X compounds, several characteristics are discussed including temperature dependence and concentration dependence of spin relaxation times, superconductivity and the importance of d-state electrons in determination of the spin relaxation times. Finally, the above characteristics were determined for 6 different samples of the vanadium-gold alloy, V 3 Au, specifically

On the factors controlling occurrence of F-region coherent echoes

Directory of Open Access Journals (Sweden)

D. W. Danskin

2002-09-01

Full Text Available Several factors are known to control the HF echo occurrence rate, including electron density distribution in the ionosphere (affecting the propagation path of the radar wave, D-region radio wave absorption, and ionospheric irregularity intensity. In this study, we consider 4 days of CUTLASS Finland radar observations over an area where the EISCAT incoherent scatter radar has continuously monitored ionospheric parameters. We illustrate that for the event under consideration, the D-region absorption was not the major factor affecting the echo appearance. We show that the electron density distribution and the radar frequency selection were much more significant factors. The electron density magnitude affects the echo occurrence in two different ways. For small F-region densities, a minimum value of 1 × 1011 m-3 is required to have sufficient radio wave refraction so that the orthogonality (with the magnetic field lines condition is met. For too large densities, radio wave strong "over-refraction" leads to the ionospheric echo disappearance. We estimate that the over-refraction is important for densities greater than 4 × 1011 m-3. We also investigated the backscatter power and the electric field magnitude relationship and found no obvious relationship contrary to the expectation that the gradient-drift plasma instability would lead to stronger irregularity intensity/echo power for larger electric fields.Key words. Ionosphere (ionospheric irregularities; plasma waves and instabilities; auroral ionosphere

Magnetic resonance imaging of lumbar spine. Comparison of multiple spin echo and low flip angle gradient echo imaging

Energy Technology Data Exchange (ETDEWEB)

Murakami, Takamichi; Fujita, Norihiko; Harada, Koushi; Kozuka, Takahiro (Osaka Univ. (Japan). Faculty of Medicine)

1989-07-01

Sixteen patients including 13 cases with disk herniation and 3 cases with spondylosis of lumbar spine were examined on a resistive MRI system operating at 0.1 T. All lesions were studied with both multiple spin echo (MSE) and low flip angle gradient echo (LF) techniques to evaluate which technique is more effective in detecting the disk degeneration and the indentation on subarachnoid space. MSE images were obtained with repetition time (TR) of 1100-1500 ms or cardiac gating, an echo time (TE) of 30, 60, 90, 120, 150, and 180 ms symmetrical 6 echoes, and total acquisition time of more than 281 sec. LF images were obtained with TR of 500, 250, and 100 ms, TE of 18 ms, a flip angle of 30 degree, and total acquisition time of 128 sec. Eleven lesions of spinal disk degeneration and 12 of indentation on subarachnoid space were detected with LF. On the other hand, 26 lesions of spinal disk degeneration and 38 of indentation on subarachnoid space were detected with MSE. Although the parameters of LF employed in this study were relatively effective to emphasize T2{sup *}-based contrast, the ability of LF in detection of spinal disk degeneration and indentation on subarachnoid space is less than that of MSE. Signal contrast to noise ratios for normal disk and degenerative disk, epidural-fat and disk herniated material, CSF and disk herniated material, and epidural-fat and CSF were less than 4 with LF, but more than 4 with MSE. This difference of contrast to noise ratio between MSE and LF was one of the main causes of the difference of the detection rate of spinal disk degeneration and indentation on subarachnoid space. (author).

25 CFR 212.56 - Geological and geophysical permits.

Science.gov (United States)

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Geological and geophysical permits. 212.56 Section 212.56... FOR MINERAL DEVELOPMENT Rents, Royalties, Cancellations, and Appeals § 212.56 Geological and geophysical permits. (a) Permits to conduct geological and geophysical operations on Indian lands which do not...

Significance of spin-echo intracardiac signal during cine cardiac MR imaging

International Nuclear Information System (INIS)

Feiglin, D.H.I.; O'Donnell, J.K.

1987-01-01

Thirty patient studies were performed using several multisection spin multi-echo pulse sequences (SEPS) formattable into the cine mode, with repetition time (TR)≤RR interval and 18 msec ≤ echo time (TE) ≤ 64 msec. Thirteen studies were performed in patients with various cardiomyopathies, ten in patients with cardiac tumors, and seven in healthy volunteers. The SEPS in the multi-echo acquisition format differentiated between tumor and stasis in terms of signal behavior. Healthy subjects may exhibit stasis of flow adjacent to the endocardium during the cardiac cycle

What ears do for bats: a comparative study of pinna sound pressure transformation in chiroptera.

Science.gov (United States)

Obrist, M K; Fenton, M B; Eger, J L; Schlegel, P A

1993-07-01

Using a moveable loudspeaker and an implanted microphone, we studied the sound pressure transformation of the external ears of 47 species of bats from 13 families. We compared pinna gain, directionality of hearing and interaural intensity differences (IID) in echolocating and non-echolocating bats, in species using different echolocation strategies and in species that depend upon prey-generated sounds to locate their targets. In the Pteropodidae, two echolocating species had slightly higher directionality than a non-echolocating species. The ears of phyllostomid and vespertilionid species showed moderate directionality. In the Mormoopidae, the ear directionality of Pteronotus parnellii clearly matched the dominant spectral component of its echolocation calls, unlike the situation in three other species. Species in the Emballonuridae, Molossidae, Rhinopomatidae and two vespertilionids that use narrow-band search-phase echolocation calls showed increasingly sharp tuning of the pinna to the main frequency of their signals. Similar tuning was most evident in Hipposideridae and Rhinolophidae, species specialized for flutter detection via Doppler-shifted echoes of high-duty-cycle narrow-band signals. The large pinnae of bats that use prey-generated sounds to find their targets supply high sound pressure gain at lower frequencies. Increasing domination of a narrow spectral band in echolocation is reflected in the passive acoustic properties of the external ears (sharper directionality). The importance of IIDs for lateralization and horizontal localization is discussed by comparing the behavioural directional performance of bats with their bioacoustical features.

Water Pollution Search Results Help - TRI | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

TRI DMR Dashboard Summary Table.png | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

TRI DMR Dashboard Top Industries Graph.png | ECHO | US ...

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

TRI DMR Dashboard Pie Chart.png | ECHO | US EPA

Science.gov (United States)

ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

Rapid Geophysical Surveyor

International Nuclear Information System (INIS)

Roybal, L.G.; Carpenter, G.S.; Josten, N.E.

1993-01-01

The Rapid Geophysical Surveyor (RGS) is a system designed to rapidly and economically collect closely-spaced geophysical data used for characterization of US Department of Energy waste sites. Geophysical surveys of waste sites are an important first step in the remediation and closure of these sites; especially older sites where historical records are inaccurate and survey benchmarks have changed because of refinements in coordinate controls and datum changes. Closely-spaced data are required to adequately differentiate pits, trenches, and soil vault rows whose edges may be only a few feet from each other. A prototype vehicle designed to collect magnetic field data was built at the Idaho National Engineering Laboratory (INEL) during the summer of 1992. The RGS was funded by the Buried Waste Integrated Demonstration program. This vehicle was demonstrated at the Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex at the INEL in September 1992. Magnetic data were collected over two areas in the SDA, with a total survey area of about 1.7 acres. Data were collected at a nominal density of 2 1/2 in. along survey lines spaced 1-ft apart. Over 350,000 data points were collected over a 6 day period corresponding to about 185 worker-days using conventional ground survey techniques

Geophysical evidence for melt in the deep lunar interior and implications for lunar evolution

Science.gov (United States)

Khan, A.; Connolly, J. A. D.; Pommier, A.; Noir, J.

2014-10-01

Analysis of lunar laser ranging and seismic data has yielded evidence that has been interpreted to indicate a molten zone in the lowermost mantle overlying a fluid core. Such a zone provides strong constraints on models of lunar thermal evolution. Here we determine thermochemical and physical structure of the deep Moon by inverting lunar geophysical data (mean mass and moment of inertia, tidal Love number, and electromagnetic sounding data) in combination with phase-equilibrium computations. Specifically, we assess whether a molten layer is required by the geophysical data. The main conclusion drawn from this study is that a region with high dissipation located deep within the Moon is required to explain the geophysical data. This region is located within the mantle where the solidus is crossed at a depth of ˜1200 km (≥1600°C). Inverted compositions for the partially molten layer (150-200 km thick) are enriched in FeO and TiO2 relative to the surrounding mantle. The melt phase is neutrally buoyant at pressures of ˜4.5-4.6 GPa but contains less TiO2 (<15 wt %) than the Ti-rich (˜16 wt %) melts that produced a set of high-density primitive lunar magmas (density of 3.4 g/cm3). Melt densities computed here range from 3.25 to 3.45 g/cm3 bracketing the density of lunar magmas with moderate-to-high TiO2 contents. Our results are consistent with a model of lunar evolution in which the cumulate pile formed from crystallization of the magma ocean as it overturned, trapping heat-producing elements in the lower mantle.

The hydrocarbon accumulations mapping in crystalline rocks by mobile geophysical methods

Science.gov (United States)

Nesterenko, A.

2013-05-01

Sedimentary-migration origin theory of hydrocarbons dominates nowadays. However, a significant amount of hydrocarbon deposits were discovered in the crystalline rocks, which corroborates the theory of non-organic origin of hydrocarbons. During the solving of problems of oil and gas exploration in crystalline rocks and arrays so-called "direct" methods can be used. These methods include geoelectric methods of forming short-pulsed electromagnetic field (FSPEF) and vertical electric-resonance sounding (VERS) (FSPEF-VERS express-technology). Use of remote Earth sounding (RES) methods is also actual. These mobile technologies are extensively used during the exploration of hydrocarbon accumulations in crystalline rocks, including those within the Ukrainian crystalline shield. The results of explorations Four anomalous geoelectric zones of "gas condensate reservoir" type were quickly revealed as a result of reconnaissance prospecting works (Fig. 1). DTA "Obukhovychi". Anomaly was traced over a distance of 4 km. Approximate area is 12.0 km2. DTA"Korolevskaya". Preliminary established size of anomalous zone is 10.0 km2. The anomalous polarized layers of gas and gas-condensate type were determined. DTA "Olizarovskaya". Approximate size of anomaly is about 56.0 km2. This anomaly is the largest and the most intense. DTA "Druzhba". Preliminary estimated size of anomaly is 16.0 km2. Conclusions Long experience of a successful application of non-classical geoelectric methods for the solving of variety of practical tasks allow one to state their contribution to the development of a new paradigm of geophysical researches. Simultaneous usage of the remote sensing data processing and interpretation method and FSPEF and VERS technologies can essentially optimize and speed up geophysical work. References 1. S.P. Levashov. Detection and mapping of anomalies of "hydrocarbon deposit" type in the fault zones of crystalline arrays by geoelectric methods. / S.P. Levashov, N.A. Yakymchuk, I

Stationary echo canceling in velocity estimation by time-domain cross-correlation

DEFF Research Database (Denmark)

Jensen, Jørgen Arendt

1993-01-01

The application of stationary echo canceling to ultrasonic estimation of blood velocities using time-domain cross-correlation is investigated. Expressions are derived that show the influence from the echo canceler on the signals that enter the cross-correlation estimator. It is demonstrated...

Myocardial viability: comparison of free-breathing navigator-echo-gated three-dimensional inversion-recovery gradient-echo MR and standard multiple breath-hold two-dimensional inversion-recovery gradient-echo MR

International Nuclear Information System (INIS)

Kim, Jin Hee; Seo, Joon Beom; Do, Kyung Hyun; Yang, Dong Hyun; Lee, Soo Hyun; Ko, Sung Min; Heo, Jeong Nam; Lim, Tae Hwan

2004-01-01

To compare a free-breathing, navigator-echo-gated, three-dimensional, inversion-recovery, gradient-echo, MR pulse sequence (3D-MRI) with standard, multiple breath-hold, two-dimensional, inversion-recovery, gradient-echo MR (2D-MRI) for the evaluation of delayed hyperenhancement of nonviable myocardium in patients with chronic ischemic heart disease. Ten patients with chronic ischemic heart disease were enrolled in this study. MRI was performed on a 1.5-T system. 3D-MRI was obtained in the short axis plane at 10 minutes after the administration of Gd-DTPA (0.2 mmol/kg, 4 cc/sec). Prospective gating of the acquisition based on the navigator echo was applied. 2D-MRI was performed immediately after finishing 3D-MRI. The area of total and hyperenhanced myocardium measured on both image sets was compared with paired Student t-test and Bland-Altman method. By using a 60-segment model, the transmural extent and segment width of the hyperenhanced area were recorded by 3-scale grading method. The agreement between the two sequences was evaluated with kappa statistics. We also evaluated the agreement of hyperenhancement among the three portions (apical, middle and basal portion) of the left ventricle with kappa statistics. The two sequences showed good agreement for the measured area of total and hyperenhanced myocardium on paired t-test (ρ = 0.11 and ρ = 0.34, respectively). No systematic bias was shown on Bland-Altman analysis. Good agreement was found for the segmental width (Κ = 0.674) and transmural extent (Κ = 0.615) of hyperenhancement on the segmented analysis. However, the agreement of the transmural extent of hyperenhancement in the apical segments was relatively poor compared with that in the middle or basal portions. This study showed good agreement between 3D-MRI and 2D-MRI in evaluation of non-viable myocardium. Therefore, 3D-MRI may be useful in the assessment of myocardial viability in patients with dyspnea and children because it allows free

Observation of the geometric phase using photon echoes

International Nuclear Information System (INIS)

Tian, Mingzhen; Reibel, Randy R.; Barber, Zeb W.; Fischer, Joe A.; Babbitt, Wm. Randall

2003-01-01

The geometric phase of an atomic system has been observed in V-type three-level barium atoms using photon echoes. The geometric phase results from a cyclic evolution of a two-level subsystem driven by a laser pulse. The phase change is observed on the echo field produced on a different subsystem that is coupled via the ground state to the driven subsystem. The measured geometric phase was half of the solid angle subtended by the Bloch vector along the driven evolution circuit. This evolution has the potential to form universal operations of quantum bits

Unleashing Geophysics Data with Modern Formats and Services

Science.gov (United States)

Ip, Alex; Brodie, Ross C.; Druken, Kelsey; Bastrakova, Irina; Evans, Ben; Kemp, Carina; Richardson, Murray; Trenham, Claire; Wang, Jingbo; Wyborn, Lesley

2016-04-01

Geoscience Australia (GA) is the national steward of large volumes of geophysical data extending over the entire Australasian region and spanning many decades. The volume and variety of data which must be managed, coupled with the increasing need to support machine-to-machine data access, mean that the old "click-and-ship" model delivering data as downloadable files for local analysis is rapidly becoming unviable - a "big data" problem not unique to geophysics. The Australian Government, through the Research Data Services (RDS) Project, recently funded the Australian National Computational Infrastructure (NCI) to organize a wide range of Earth Systems data from diverse collections including geoscience, geophysics, environment, climate, weather, and water resources onto a single High Performance Data (HPD) Node. This platform, which now contains over 10 petabytes of data, is called the National Environmental Research Data Interoperability Platform (NERDIP), and is designed to facilitate broad user access, maximise reuse, and enable integration. GA has contributed several hundred terabytes of geophysical data to the NERDIP. Historically, geophysical datasets have been stored in a range of formats, with metadata of varying quality and accessibility, and without standardised vocabularies. This has made it extremely difficult to aggregate original data from multiple surveys (particularly un-gridded geophysics point/line data) into standard formats suited to High Performance Computing (HPC) environments. To address this, it was decided to use the NERDIP-preferred Hierarchical Data Format (HDF) 5, which is a proven, standard, open, self-describing and high-performance format supported by extensive software tools, libraries and data services. The Network Common Data Form (NetCDF) 4 API facilitates the use of data in HDF5, whilst the NetCDF Climate & Forecasting conventions (NetCDF-CF) further constrain NetCDF4/HDF5 data so as to provide greater inherent interoperability

Sound algorithms

OpenAIRE

De Götzen , Amalia; Mion , Luca; Tache , Olivier

2007-01-01

International audience; We call sound algorithms the categories of algorithms that deal with digital sound signal. Sound algorithms appeared in the very infancy of computer. Sound algorithms present strong specificities that are the consequence of two dual considerations: the properties of the digital sound signal itself and its uses, and the properties of auditory perception.

Description of geophysical data in the SKB database GEOTAB

International Nuclear Information System (INIS)

Sehlstedt, S.

1988-02-01

For the storage of different types of data collected by SKB a database called Geotab has been created. The following data are stored in the database: Background data, geological data, geophysical data, hydrogeological data, hydrochemical data. This report describes the data flow for different types of geophysical measurements. The descriptions start with measurements and end with the storage of data in Geotab. Each process and the resulting data volume is presented separately. The geophysical measurements have been divided into the following subjects: Geophysical ground surface measurements, profile measurements; geophysical ground surface measurements, grid net measurements; geophysical borehole logging; petrophysical measurements. Each group of measurements is described in an individual chapter. In each chapter several measuring techniques are described and each method has a data table and a flyleaf table in Geotab. (orig.)

Topography of sound level representation in the FM sweep selective region of the pallid bat auditory cortex.

Science.gov (United States)

Measor, Kevin; Yarrow, Stuart; Razak, Khaleel A

2018-05-26

Sound level processing is a fundamental function of the auditory system. To determine how the cortex represents sound level, it is important to quantify how changes in level alter the spatiotemporal structure of cortical ensemble activity. This is particularly true for echolocating bats that have control over, and often rapidly adjust, call level to actively change echo level. To understand how cortical activity may change with sound level, here we mapped response rate and latency changes with sound level in the auditory cortex of the pallid bat. The pallid bat uses a 60-30 kHz downward frequency modulated (FM) sweep for echolocation. Neurons tuned to frequencies between 30 and 70 kHz in the auditory cortex are selective for the properties of FM sweeps used in echolocation forming the FM sweep selective region (FMSR). The FMSR is strongly selective for sound level between 30 and 50 dB SPL. Here we mapped the topography of level selectivity in the FMSR using downward FM sweeps and show that neurons with more monotonic rate level functions are located in caudomedial regions of the FMSR overlapping with high frequency (50-60 kHz) neurons. Non-monotonic neurons dominate the FMSR, and are distributed across the entire region, but there is no evidence for amplitopy. We also examined how first spike latency of FMSR neurons change with sound level. The majority of FMSR neurons exhibit paradoxical latency shift wherein the latency increases with sound level. Moreover, neurons with paradoxical latency shifts are more strongly level selective and are tuned to lower sound level than neurons in which latencies decrease with level. These data indicate a clustered arrangement of neurons according to monotonicity, with no strong evidence for finer scale topography, in the FMSR. The latency analysis suggests mechanisms for strong level selectivity that is based on relative timing of excitatory and inhibitory inputs. Taken together, these data suggest how the spatiotemporal

Geophysical Responses of Hydrocarbon-impacted Zones at the Various Contamination Conditions

Science.gov (United States)

Kim, C.; Ko, K.; Son, J.; Kim, J.

2008-12-01

aged LNAPL- impacted sites, and (3) high electrical resistivity anomalies at the fresh or aged sites contaminated with residual products of crude oils (lubricating oils). The study results also show that the geophysical methods, as a non-invasive sounding technique, can be effectively applied to mapping hydrocarbon-contaminated zones.

46 CFR 7.20 - Nantucket Sound, Vineyard Sound, Buzzards Bay, Narragansett Bay, MA, Block Island Sound and...

Science.gov (United States)

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Nantucket Sound, Vineyard Sound, Buzzards Bay, Narragansett Bay, MA, Block Island Sound and easterly entrance to Long Island Sound, NY. 7.20 Section 7.20... Atlantic Coast § 7.20 Nantucket Sound, Vineyard Sound, Buzzards Bay, Narragansett Bay, MA, Block Island...

Application of fast spin-echo T2-weighted imaging for examination of the neurocranium. Comparison with the conventional T2-weighted spin-echo sequence

International Nuclear Information System (INIS)

Siewert, C.; Hosten, N.; Felix, R.

1994-01-01

T 2 -weighted spin-echo imaging is the standard screening procedure in MR imaging of the neutrocranium. We evaluated fast spin-echo T 2 -weighted imaging (TT 2 ) of the neurocranium in comparison to conventional spin-echo T 2 -weighted imaging (T 2 ). Signal-to-noise and contrast-to-noise ratio of normal brain tissues (basal ganglia, grey and white matter, CSF fluid) and different pathologies were calculated. Signal-to-noise ratio and contrast-to-noise ratio were significantly higher than TT 2 than in T 2 (with the exception of grey-to-white matter contrast). Tissues with increased content of water protons (mobile protons) showed the highest contrast to surrounding tissues. The increased signal intensity of fat must be given due attention in fatty lesions. Because the contrast-to-noise ratio between white matter and basal ganglia is less in TT 2 , Parkinson patients have to be examined by conventional T 2 . If these limitations are taken into account, fast spin-echo T 2 -weighted imaging is well appropriate for MR imaging of the neurocranium, resulting in heavy T 2 -weighting achieved in a short acquisition time. (orig.) [de

Echo III: The study of electric and magnetic fields with conjugate echoes from artificial electron beams injected into the auroral zone ionosphere

International Nuclear Information System (INIS)

Hendrickson, R.A.; Winckler, J.R.; Arnoldy, R.L.

1976-01-01

The third in a series of rocket flights carrying large electron guns for electron beam-plasma analysis and magnetosphere probing has been carried out from the Poker Flat rocket range near Fairbanks, Alaska at L=6. Echoes from the injected electrons mirroring at the southern hemisphere conjugate point were observed on the rocket by particle detectors and in the nearby ionosphere by photometers on board the rocket. The bounce time and drift velocities of the echoes were measured using the known trajectory and aspect of the rocket. Ionospheric electric fields near the rocket were inferred from drift motion of the ambient ion population measured by two techniques, electrostatic analyzers on board the rocket and incoherent backscatter radar from the ground. Using model magnetic fields, gradient and curvature drift and bound times have been computed under the conditions appropriate for this experiment. Assuming that field lines are equipotentials, the addition of the observed ionospheric electric field drift to the model-independent gradient and curvature drifts predicts a net echo drift velocity that is in agreement with the observations, provided the Mead-Fairfield 1972--73 model is used. The observed bounce time constitutes an independent model check and is in better agreement with the Olson-Pfitzer model. Echo spatial and temporal fluctuations reflected the turbulence associated with the diffuse aurora into which the rocket was launched

Gaussian-approximation formalism for evaluating decay of NMR spin echoes

International Nuclear Information System (INIS)

Recchia, C.H.; Gorny, K.; Pennington, C.H.

1996-01-01

We present a formalism for evaluating the amplitude of the NMR spin echo and stimulated echo as a function of pulse spacings, for situations in which the nuclear spins experience an effective longitudinal magnetic field h z (t) resulting from an arbitrary number of independent sources, each characterized by its own arbitrary time correlation function. The distribution of accumulated phase angles for the ensemble of nuclear spins at the time of the echo is approximated as a Gaussian. The development of the formalism is motivated by the need to understand the transverse relaxation of 89 Y in YBa 2 Cu 3 O 7 , in which the 89 Y experiences 63,65 Cu dipolar fields which fluctuate due to 63,65 Cu T 1 processes. The formalism is applied successfully to this example, and to the case of nuclei diffusing in a spatially varying magnetic field. Then we examine a situation in which the approximation fails emdash the classic problem of chemical exchange in dimethylformamide, where the methyl protons experience a chemical shift which fluctuates between two discrete values. In this case the Gaussian approximation yields a monotonic decay of the echo amplitude with increasing pulse spacing, while the exact solution yields distinct open-quote open-quote beats close-quote close-quote in the echo height, which we confirm experimentally. In light of this final example the limits of validity of the approximation are discussed. copyright 1996 The American Physical Society

NovoPen Echo® insulin delivery device

Directory of Open Access Journals (Sweden)

Hyllested-Winge J

2016-01-01

Full Text Available Jacob Hyllested-Winge,1 Thomas Sparre,2 Line Kynemund Pedersen2 1Novo Nordisk Pharma Ltd, Tokyo, Japan; 2Novo Nordisk A/S, Søborg, Denmark Abstract: The introduction of insulin pen devices has provided easier, well-tolerated, and more convenient treatment regimens for patients with diabetes mellitus. When compared with vial and syringe regimens, insulin pens offer a greater clinical efficacy, improved quality of life, and increased dosing accuracy, particularly at low doses. The portable and discreet nature of pen devices reduces the burden on the patient, facilitates adherence, and subsequently contributes to the improvement in glycemic control. NovoPen Echo® is one of the latest members of the NovoPen® family that has been specifically designed for the pediatric population and is the first to combine half-unit increment (=0.5 U of insulin dosing with a simple memory function. The half-unit increment dosing amendments and accurate injection of 0.5 U of insulin are particularly beneficial for children (and insulin-sensitive adults/elders, who often require small insulin doses. The memory function can be used to record the time and amount of the last dose, reducing the fear of double dosing or missing a dose. The memory function also provides parents with extra confidence and security that their child is taking insulin at the correct doses and times. NovoPen Echo is a lightweight, durable insulin delivery pen; it is available in two different colors, which may help to distinguish between different types of insulin, providing more confidence for both users and caregivers. Studies have demonstrated a high level of patient satisfaction, with 80% of users preferring NovoPen Echo to other pediatric insulin pens. Keywords: NovoPen Echo®, memory function, half-unit increment dosing, adherence, children, adolescents 

Calibration and Confirmation in Geophysical Models

Science.gov (United States)

Werndl, Charlotte

2016-04-01

For policy decisions the best geophysical models are needed. To evaluate geophysical models, it is essential that the best available methods for confirmation are used. A hotly debated issue on confirmation in climate science (as well as in philosophy) is the requirement of use-novelty (i.e. that data can only confirm models if they have not already been used before. This talk investigates the issue of use-novelty and double-counting for geophysical models. We will see that the conclusions depend on the framework of confirmation and that it is not clear that use-novelty is a valid requirement and that double-counting is illegitimate.

Mono-Exponential Fitting in T2-Relaxometry: Relevance of Offset and First Echo.

Directory of Open Access Journals (Sweden)

David Milford

Full Text Available T2 relaxometry has become an important tool in quantitative MRI. Little focus has been put on the effect of the refocusing flip angle upon the offset parameter, which was introduced to account for a signal floor due to noise or to long T2 components. The aim of this study was to show that B1 imperfections contribute significantly to the offset. We further introduce a simple method to reduce the systematic error in T2 by discarding the first echo and using the offset fitting approach.Signal curves of T2 relaxometry were simulated based on extended phase graph theory and evaluated for 4 different methods (inclusion and exclusion of the first echo, while fitting with and without the offset. We further performed T2 relaxometry in a phantom at 9.4T magnetic resonance imaging scanner and used the same methods for post-processing as in the extended phase graph simulated data. Single spin echo sequences were used to determine the correct T2 time.The simulation data showed that the systematic error in T2 and the offset depends on the refocusing pulse, the echo spacing and the echo train length. The systematic error could be reduced by discarding the first echo. Further reduction of the systematic T2 error was reached by using the offset as fitting parameter. The phantom experiments confirmed these findings.The fitted offset parameter in T2 relaxometry is influenced by imperfect refocusing pulses. Using the offset as a fitting parameter and discarding the first echo is a fast and easy method to minimize the error in T2, particularly for low to intermediate echo train length.

Fundamentals of Geophysics

Science.gov (United States)

Frohlich, Cliff

Choosing an intermediate-level geophysics text is always problematic: What should we teach students after they have had introductory courses in geology, math, and physics, but little else? Fundamentals of Geophysics is aimed specifically at these intermediate-level students, and the author's stated approach is to construct a text “using abundant diagrams, a simplified mathematical treatment, and equations in which the student can follow each derivation step-by-step.” Moreover, for Lowrie, the Earth is round, not flat—the “fundamentals of geophysics” here are the essential properties of our Earth the planet, rather than useful techniques for finding oil and minerals. Thus this book is comparable in both level and approach to C. M. R. Fowler's The Solid Earth (Cambridge University Press, 1990).

Geophysical and geochemical techniques for exploration of hydrocarbons and minerals

International Nuclear Information System (INIS)

Sittig, M.

1980-01-01

The detailed descriptive information in this book is based on 389 US patents that deal with geophysical and geochemical techniques useful for the exploration of hydrocarbons and minerals. Where it was necessary to round out the complete technological picture, a few paragraphs from cited government reports have been included. These techniques are used in prospecting for oil, coal, oil shale, tar sand and minerals. The patents are grouped under the following chapters: geochemical prospecting; geobiological prospecting; geophysical exploration; magnetic geophysical prospecting; gravitational geophysical prospecting; electrical geophysical prospecting; nuclear geophysical prospecting; seismic geophysical prospecting; and exploratory well drilling. This book serves a double purpose in that it supplies detailed technical information and can be used as a guide to the US patent literature in this field. By indicating all the information that is significant, and eliminating legal jargon and juristic phraseology, this book presents an advanced, industrially oriented review of modern methods of geophysical and geochemical exploration techniques

Multiband multi-echo imaging of simultaneous oxygenation and flow timeseries for resting state connectivity.

Science.gov (United States)

Cohen, Alexander D; Nencka, Andrew S; Lebel, R Marc; Wang, Yang

2017-01-01

A novel sequence has been introduced that combines multiband imaging with a multi-echo acquisition for simultaneous high spatial resolution pseudo-continuous arterial spin labeling (ASL) and blood-oxygenation-level dependent (BOLD) echo-planar imaging (MBME ASL/BOLD). Resting-state connectivity in healthy adult subjects was assessed using this sequence. Four echoes were acquired with a multiband acceleration of four, in order to increase spatial resolution, shorten repetition time, and reduce slice-timing effects on the ASL signal. In addition, by acquiring four echoes, advanced multi-echo independent component analysis (ME-ICA) denoising could be employed to increase the signal-to-noise ratio (SNR) and BOLD sensitivity. Seed-based and dual-regression approaches were utilized to analyze functional connectivity. Cerebral blood flow (CBF) and BOLD coupling was also evaluated by correlating the perfusion-weighted timeseries with the BOLD timeseries. These metrics were compared between single echo (E2), multi-echo combined (MEC), multi-echo combined and denoised (MECDN), and perfusion-weighted (PW) timeseries. Temporal SNR increased for the MECDN data compared to the MEC and E2 data. Connectivity also increased, in terms of correlation strength and network size, for the MECDN compared to the MEC and E2 datasets. CBF and BOLD coupling was increased in major resting-state networks, and that correlation was strongest for the MECDN datasets. These results indicate our novel MBME ASL/BOLD sequence, which collects simultaneous high-resolution ASL/BOLD data, could be a powerful tool for detecting functional connectivity and dynamic neurovascular coupling during the resting state. The collection of more than two echoes facilitates the use of ME-ICA denoising to greatly improve the quality of resting state functional connectivity MRI.

Air Dashboard Help | ECHO | US EPA

Science.gov (United States)

The dashboards found on the Enforcement and Compliance History Online (ECHO) website are specialized to track both facility and agency performance as they relate to compliance with and enforcement of environmental standards under the Clean Air Act (CAA).

Evolution of Web Services in EOSDIS: Search and Order Metadata Registry (ECHO)

Science.gov (United States)

Mitchell, Andrew; Ramapriyan, Hampapuram; Lowe, Dawn

2009-01-01

During 2005 through 2008, NASA defined and implemented a major evolutionary change in it Earth Observing system Data and Information System (EOSDIS) to modernize its capabilities. This implementation was based on a vision for 2015 developed during 2005. The EOSDIS 2015 Vision emphasizes increased end-to-end data system efficiency and operability; increased data usability; improved support for end users; and decreased operations costs. One key feature of the Evolution plan was achieving higher operational maturity (ingest, reconciliation, search and order, performance, error handling) for the NASA s Earth Observing System Clearinghouse (ECHO). The ECHO system is an operational metadata registry through which the scientific community can easily discover and exchange NASA's Earth science data and services. ECHO contains metadata for 2,726 data collections comprising over 87 million individual data granules and 34 million browse images, consisting of NASA s EOSDIS Data Centers and the United States Geological Survey's Landsat Project holdings. ECHO is a middleware component based on a Service Oriented Architecture (SOA). The system is comprised of a set of infrastructure services that enable the fundamental SOA functions: publish, discover, and access Earth science resources. It also provides additional services such as user management, data access control, and order management. The ECHO system has a data registry and a services registry. The data registry enables organizations to publish EOS and other Earth-science related data holdings to a common metadata model. These holdings are described through metadata in terms of datasets (types of data) and granules (specific data items of those types). ECHO also supports browse images, which provide a visual representation of the data. The published metadata can be mapped to and from existing standards (e.g., FGDC, ISO 19115). With ECHO, users can find the metadata stored in the data registry and then access the data either

Enforcement and Compliance History Online (ECHO) Facilities

Data.gov (United States)

U.S. Environmental Protection Agency — ECHO provides integrated compliance and enforcement information for about 800,000 regulated facilities nationwide. Its features range from simple to advanced,...

Photon echo with a few photons in two-level atoms

International Nuclear Information System (INIS)

Bonarota, M; Dajczgewand, J; Louchet-Chauvet, A; Le Gouët, J-L; Chanelière, T

2014-01-01

To store and retrieve signals at the single photon level, various photon echo schemes have resorted to complex preparation steps involving ancillary shelving states in multi-level atoms. For the first time, we experimentally demonstrate photon echo operation at such a low signal intensity without any preparation step, which allows us to work with mere two-level atoms. This simplified approach relies on the so-coined ‘revival of silenced echo’ (ROSE) scheme. Low noise conditions are obtained by returning the atoms to the ground state before the echo emission. In the present paper we manage ROSE in photon counting conditions, showing that very strong control fields can be compatible with extremely weak signals, making ROSE consistent with quantum memory requirements. (paper)

Marine geophysical data management and presentation system

Digital Repository Service at National Institute of Oceanography (India)

Kunte, P.D.

) of the National Institute of Oceanography, Goa, India. GPDMPS is designed for the computerized storage retrieval and presentation of marine geophysical data and information. For the systematic management of geophysical data and information, GPDMPS is subdivided...

Temperature sheets and aspect sensitive radar echoes

Directory of Open Access Journals (Sweden)

H. Luce

Full Text Available here have been years of discussion and controversy about the existence of very thin and stable temperature sheets and their relationship to the VHF radar aspect sensitivity. It is only recently that very high-resolution in situ temperature observations have brought credence to the reality and ubiquity of these structures in the free atmosphere and to their contribution to radar echo enhancements along the vertical. Indeed, measurements with very high-resolution sensors are still extremely rare and rather difficult to obtain outside of the planetary boundary layer. They have only been carried out up to the lower stratosphere by Service d’A´ eronomie (CNRS, France for about 10 years. The controversy also persisted due to the volume resolution of the (Mesosphere-Stratosphere-Troposphere VHF radars which is coarse with respect to sheet thickness, although widely sufficient for meteorological or mesoscale investigations. The contribution within the range gate of many of these structures, which are advected by the wind, and decay and grow at different instants and could be distorted either by internal gravity waves or turbulence fields, could lead to radar echoes with statistical properties similar to those produced by anisotropic turbulence. Some questions thus remain regarding the manner in which temperature sheets contribute to VHF radar echoes. In particular, the zenithal and azimuthal angular dependence of the echo power may not only be produced by diffuse reflection on stable distorted or corrugated sheets, but also by extra contributions from anisotropic turbulence occurring in the stratified atmosphere. Thus, for several years, efforts have been put forth to improve the radar height resolution in order to better describe thin structures. Frequency interferometric techniques are widely used and have been recently further developed with the implementation of high-resolution data processings. We begin by reviewing briefly some characteristics

Temperature sheets and aspect sensitive radar echoes

Directory of Open Access Journals (Sweden)

H. Luce

2001-08-01

Full Text Available here have been years of discussion and controversy about the existence of very thin and stable temperature sheets and their relationship to the VHF radar aspect sensitivity. It is only recently that very high-resolution in situ temperature observations have brought credence to the reality and ubiquity of these structures in the free atmosphere and to their contribution to radar echo enhancements along the vertical. Indeed, measurements with very high-resolution sensors are still extremely rare and rather difficult to obtain outside of the planetary boundary layer. They have only been carried out up to the lower stratosphere by Service d’A´ eronomie (CNRS, France for about 10 years. The controversy also persisted due to the volume resolution of the (Mesosphere-Stratosphere-Troposphere VHF radars which is coarse with respect to sheet thickness, although widely sufficient for meteorological or mesoscale investigations. The contribution within the range gate of many of these structures, which are advected by the wind, and decay and grow at different instants and could be distorted either by internal gravity waves or turbulence fields, could lead to radar echoes with statistical properties similar to those produced by anisotropic turbulence. Some questions thus remain regarding the manner in which temperature sheets contribute to VHF radar echoes. In particular, the zenithal and azimuthal angular dependence of the echo power may not only be produced by diffuse reflection on stable distorted or corrugated sheets, but also by extra contributions from anisotropic turbulence occurring in the stratified atmosphere. Thus, for several years, efforts have been put forth to improve the radar height resolution in order to better describe thin structures. Frequency interferometric techniques are widely used and have been recently further developed with the implementation of high-resolution data processings. We begin by reviewing briefly some characteristics

Thin-Sheet Inversion Modeling of Geomagnetic Deep Sounding Data Using MCMC Algorithm

Directory of Open Access Journals (Sweden)

Hendra Grandis

2013-01-01

Full Text Available The geomagnetic deep sounding (GDS method is one of electromagnetic (EM methods in geophysics that allows the estimation of the subsurface electrical conductivity distribution. This paper presents the inversion modeling of GDS data employing Markov Chain Monte Carlo (MCMC algorithm to evaluate the marginal posterior probability of the model parameters. We used thin-sheet model to represent quasi-3D conductivity variations in the heterogeneous subsurface. The algorithm was applied to invert field GDS data from the zone covering an area that spans from eastern margin of the Bohemian Massif to the West Carpathians in Europe. Conductivity anomalies obtained from this study confirm the well-known large-scale tectonic setting of the area.

Application of fast spin-echo T[sub 2]-weighted imaging for examination of the neurocranium. Comparison with the conventional T[sub 2]-weighted spin-echo sequence. Die Anwendung der T[sub 2]-gewichteten Turbo-Spin-Echo-Sequenz zur Untersuchung des Neurokraniums. Vergleich mit der konventionellen T[sub 2]-gewichteten Spin-Echo-Sequenz

Energy Technology Data Exchange (ETDEWEB)

Siewert, C. (Strahlenklinik und Poliklinik, Universitaets-Klinikum Rudolf Virchow, Standort Wedding, Freie Univ. Berlin (Germany)); Hosten, N. (Strahlenklinik und Poliklinik, Universitaets-Klinikum Rudolf Virchow, Standort Wedding, Freie Univ. Berlin (Germany)); Felix, R. (Strahlenklinik und Poliklinik, Universitaets-Klinikum Rudolf Virchow, Standort Wedding, Freie Univ. Berlin (Germany))

1994-07-01

T[sub 2]-weighted spin-echo imaging is the standard screening procedure in MR imaging of the neutrocranium. We evaluated fast spin-echo T[sub 2]-weighted imaging (TT[sub 2]) of the neurocranium in comparison to conventional spin-echo T[sub 2]-weighted imaging (T[sub 2]). Signal-to-noise and contrast-to-noise ratio of normal brain tissues (basal ganglia, grey and white matter, CSF fluid) and different pathologies were calculated. Signal-to-noise ratio and contrast-to-noise ratio were significantly higher than TT[sub 2] than in T[sub 2] (with the exception of grey-to-white matter contrast). Tissues with increased content of water protons (mobile protons) showed the highest contrast to surrounding tissues. The increased signal intensity of fat must be given due attention in fatty lesions. Because the contrast-to-noise ratio between white matter and basal ganglia is less in TT[sub 2], Parkinson patients have to be examined by conventional T[sub 2]. If these limitations are taken into account, fast spin-echo T[sub 2]-weighted imaging is well appropriate for MR imaging of the neurocranium, resulting in heavy T[sub 2]-weighting achieved in a short acquisition time. (orig.)

Pesticide Dashboard Help | ECHO | US EPA

Science.gov (United States)

The dashboards found on the Enforcement and Compliance History Online (ECHO) website are specialized to track both facility and agency performance as they relate to compliance with and enforcement of environmental standards under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

HTTP-based Search and Ordering Using ECHO's REST-based and OpenSearch APIs

Science.gov (United States)

Baynes, K.; Newman, D. J.; Pilone, D.

2012-12-01

Metadata is an important entity in the process of cataloging, discovering, and describing Earth science data. NASA's Earth Observing System (EOS) ClearingHOuse (ECHO) acts as the core metadata repository for EOSDIS data centers, providing a centralized mechanism for metadata and data discovery and retrieval. By supporting both the ESIP's Federated Search API and its own search and ordering interfaces, ECHO provides multiple capabilities that facilitate ease of discovery and access to its ever-increasing holdings. Users are able to search and export metadata in a variety of formats including ISO 19115, json, and ECHO10. This presentation aims to inform technically savvy clients interested in automating search and ordering of ECHO's metadata catalog. The audience will be introduced to practical and applicable examples of end-to-end workflows that demonstrate finding, sub-setting and ordering data that is bound by keyword, temporal and spatial constraints. Interaction with the ESIP OpenSearch Interface will be highlighted, as will ECHO's own REST-based API.

Light echoes - Type II supernovae

International Nuclear Information System (INIS)

Schaefer, B.E.

1987-01-01

Type II supernovae (SNs) light curves show a remarkable range of shapes. Data have been collected for the 12 Type II SNs that have light curve information for more than four months past maximum. Contrary to previous reports, it is found that (1) the decay rate after 100 days past maximum varies by almost an order of magnitude and (2) the light curve shapes are not bimodally distributed, but actually form a continuum. In addition, it is found that the extinctions to the SNs are related to the light curve shapes. This implies that the absorbing dust is local to the SNs. The dust is likely to be part of a circumstellar shell emitted by the SN progenitor that Dwek (1983) has used to explain infrared echoes. The optical depth of the shell can get quite large. In such cases, it is found that the photons scattered and delayed by reflection off dust grains will dominate the light curve several months after peak brightness. This light echo offers a straightforward explanation of the diversity of Type II SN light curves. 22 references

How to misuse echo contrast

Directory of Open Access Journals (Sweden)

Missios Anna

2009-01-01

Full Text Available Abstract Background Primary intracardiac tumours are rare, there are however several entities that can mimic tumours. Contrast echocardiography has been suggested to aid the differentiation of various suspected masses. We present a case where transthoracic echocardiography completely misdiagnosed a left atrial mass, partly due to use of echo contrast. Case presentation An 80 year-old woman was referred for transthoracic echocardiography because of one-month duration of worsening of dyspnoea. Transthoracic echocardiography displayed a large echodense mass in the left atrium. Intravenous injection of contrast (SonoVue, Bracco Inc., It indicated contrast-enhancement of the structure, suggesting tumour. Transesophageal echocardiography revealed, however, a completely normal finding in the left atrium. Subsequent gastroscopy examination showed a hiatal hernia. Conclusion It is noteworthy that the transthoracic echocardiographic exam completely misdiagnosed what seemed like a left atrial mass, which in part was an effect of the use of echo contrast. This example highlights that liberal use of transoesophageal echocardiography is often warranted if optimal display of cardiac structures is desired.

Ultrafast Dephasing and Incoherent Light Photon Echoes in Organic Amorphous Systems

Science.gov (United States)

Yano, Ryuzi; Matsumoto, Yoshinori; Tani, Toshiro; Nakatsuka, Hiroki

1989-10-01

Incoherent light photon echoes were observed in organic amorphous systems (cresyl violet in polyvinyl alcohol and 1,4-dihydroxyanthraquinone in polymethacrylic acid) by using temporally-incoherent nanosecond laser pulses. It was found that an echo decay curve of an organic amorphous system is composed of a sharp peak which decays very rapidly and a slowly decaying wing at the tail. We show that the persistent hole burning (PHB) spectra were reproduced by the Fourier-cosine transforms of the echo decay curves. We claim that in general, we must take into account the multi-level feature of the system in order to explain ultrafast dephasing at very low temperatures.

Stellar Echo Imaging of Exoplanets, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — All stars exhibit intensity fluctuations over several time scales, from nanoseconds to days; these intensity fluctuations echo off planetary bodies in the star...

Stellar Echo Imaging of Exoplanets, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — All stars exhibit intensity fluctuations over several time scales, from nanoseconds to days; these intensity fluctuations echo off planetary bodies in the star...

Improving Pain Care with Project ECHO in Community Health Centers.

Science.gov (United States)

Anderson, Daren; Zlateva, Ianita; Davis, Bennet; Bifulco, Lauren; Giannotti, Tierney; Coman, Emil; Spegman, Douglas

2017-10-01

Pain is an extremely common complaint in primary care, and patient outcomes are often suboptimal. This project evaluated the impact of Project ECHO Pain videoconference case-based learning sessions on knowledge and quality of pain care in two Federally Qualified Health Centers. Quasi-experimental, pre-post intervention, with comparison group. Two large, multisite federally qualified health centers in Connecticut and Arizona. Intervention (N = 10) and comparison (N = 10) primary care providers. Primary care providers attended 48 weekly Project ECHO Pain sessions between January and December 2013, led by a multidisciplinary pain specialty team. Surveys and focus groups assessed providers' pain-related knowledge and self-efficacy. Electronic health record data were analyzed to evaluate opioid prescribing and specialty referrals. Compared with control, primary care providers in the intervention had a significantly greater increase in pain-related knowledge and self-efficacy. Providers who attended ECHO were more likely to use formal assessment tools and opioid agreements and refer to behavioral health and physical therapy compared with control providers. Opioid prescribing decreased significantly more among providers in the intervention compared with those in the control group. Pain is an extremely common and challenging problem, particularly among vulnerable patients such as those cared for at the more than 1,200 Federally Qualified Health Centers in the United States. In this study, attendance at weekly Project ECHO Pain sessions not only improved knowledge and self-efficacy, but also altered prescribing and referral patterns, suggesting that knowledge acquired during ECHO sessions translated into practice changes. © 2017 American Academy of Pain Medicine.

Determination of Cenozoic sedimentary structures using integrated geophysical surveys: A case study in the Barkol Basin, Xinjiang, China

Science.gov (United States)

Sun, Kai; Chen, Chao; Du, Jinsong; Wang, Limin; Lei, Binhua

2018-01-01

Thickness estimation of sedimentary basin is a complex geological problem, especially in an orogenic environment. Intense and multiple tectonic movements and climate changes result in inhomogeneity of sedimentary layers and basement configurations, which making sedimentary structure modelling difficult. In this study, integrated geophysical methods, including gravity, magnetotelluric (MT) sounding and electrical resistivity tomography (ERT), were used to estimate basement relief to understand the geological structure and evolution of the eastern Barkol Basin in China. This basin formed with the uplift of the eastern Tianshan during the Cenozoic. Gravity anomaly map revealed the framework of the entire area, and ERT as well as MT sections reflected the geoelectric features of the Cenozoic two-layer distribution. Therefore, gravity data, constrained by MT, ERT and boreholes, were utilized to estimate the spatial distribution of the Quaternary layer. The gravity effect of the Quaternary layer related to the Tertiary layer was later subtracted to obtain the residual anomaly for inversion. For the Tertiary layer, the study area was divided into several parts because of lateral difference of density contrasts. Gravity data were interpreted to determine the density contrast constrained by the MT results. The basement relief can be verified by geological investigation, including the uplift process and regional tectonic setting. The agreement between geophysical survey and prior information from geology emphasizes the importance of integrated geophysical survey as a complementary means of geological studies in this region.

Depth study of insular shelf electric sounding in the Las Mercedes anomaly (Tacuarembo)[Geochemical prospection of Uranium in Uruguay]; Estudio de la profundidad del zocalo por sondeos electricos en la Anomalia de Las Mercedes (Tacuarembo)

Energy Technology Data Exchange (ETDEWEB)

Cicalese, H

1983-07-01

In the framework of Uranium prospecting Programme the geophysics team composed by BRGM and DINAMIGE workers were carried out an study about insular shelf electric sounding on the Mercedes area.They were studied the following topics: geographical location, geologic framework, methods, materials and some results.

Accurate step-FMCW ultrasound ranging and comparison with pulse-echo signaling methods

Science.gov (United States)

Natarajan, Shyam; Singh, Rahul S.; Lee, Michael; Cox, Brian P.; Culjat, Martin O.; Grundfest, Warren S.; Lee, Hua

2010-03-01

This paper presents a method setup for high-frequency ultrasound ranging based on stepped frequency-modulated continuous waves (FMCW), potentially capable of producing a higher signal-to-noise ratio (SNR) compared to traditional pulse-echo signaling. In current ultrasound systems, the use of higher frequencies (10-20 MHz) to enhance resolution lowers signal quality due to frequency-dependent attenuation. The proposed ultrasound signaling format, step-FMCW, is well-known in the radar community, and features lower peak power, wider dynamic range, lower noise figure and simpler electronics in comparison to pulse-echo systems. In pulse-echo ultrasound ranging, distances are calculated using the transmit times between a pulse and its subsequent echoes. In step-FMCW ultrasonic ranging, the phase and magnitude differences at stepped frequencies are used to sample the frequency domain. Thus, by taking the inverse Fourier transform, a comprehensive range profile is recovered that has increased immunity to noise over conventional ranging methods. Step-FMCW and pulse-echo waveforms were created using custom-built hardware consisting of an arbitrary waveform generator and dual-channel super heterodyne receiver, providing high SNR and in turn, accuracy in detection.

Geophysical Research Facility

Data.gov (United States)

Federal Laboratory Consortium — The Geophysical Research Facility (GRF) is a 60 ft long × 22 ft wide × 7 ft deep concrete basin at CRREL for fresh or saltwater investigations and can be temperature...

Application of velocity imaging and gradient-recalled echo in neuroimaging

International Nuclear Information System (INIS)

Boyko, O.B.; Pelc, N.J.; Shimakawa, A.

1990-01-01

This paper describes the initial clinical experience with imaging blood flow at 1.5 T by means of a phase-sensitive gradient refocused pulse sequence. A spin-echo flow-encoding technique was modified to a gradient recalled acquisition in a steady state sequence, producing a velocity imaging and gradient recalled echo (VIGRE) sequence (TR = 24 msec, TE = 13 msec, flip angle = 45 degrees, 24-cm field of view, 7 mm contiguous sections). Two views per phase-encoding step are acquired; one using the first-moment flow-compensation gradient waveform and the second having a (selectable) nonzero first moment. A phase subtraction image is obtained where the signal is dependent on the direction and velocity of flow. The sequence was done following routine spin-echo imaging in 35 patients

Imaging of the brain using the fast-spin-echo and gradient-spin-echo techniques

International Nuclear Information System (INIS)

Umek, W.; Ba-Ssalamah, A.; Prokesch, R.; Mallek, R.; Heimberger, K.; Hittmair, K.

1998-01-01

The aim of our study was to compare gradient-spin-echo (GRASE) to fast-spin-echo (FSE) sequences for fast T2-weighted MR imaging of the brain. Thirty-one patients with high-signal-intensity lesions on T2-weighted images were examined on a 1.5-T MR system. The FSE and GRASE sequences with identical sequence parameters were obtained and compared side by side. Image assessment criteria included lesion conspicuity, contrast between different types of normal tissue, and image artifacts. In addition, signal-to-noise, contrast-to-noise, and contrast ratios and were determined. The FSE technique demonstrated more lesions than GRASE and with generally better conspicuity. Smaller lesions in particular were better demonstrated on FSE because of lower image noise and slightly weaker image artifacts. Gray-white differentiation was better on FSE. Ferritin and hemosiderin depositions appeared darker on GRASE, which resulted in better contrast. Fatty tissue was less bright on GRASE. With current standard hardware equipment, the FSE technique seems preferable to GRASE for fast T2-weighted routine MR imaging of the brain. For the assessment of hemosiderin or ferritin depositions, GRASE might be considered. (orig.)

Integrating Multiple Geophysical Methods to Quantify Alpine Groundwater- Surface Water Interactions: Cordillera Blanca, Peru

Science.gov (United States)

Glas, R. L.; Lautz, L.; McKenzie, J. M.; Baker, E. A.; Somers, L. D.; Aubry-Wake, C.; Wigmore, O.; Mark, B. G.; Moucha, R.

2016-12-01

Groundwater- surface water interactions in alpine catchments are often poorly understood as groundwater and hydrologic data are difficult to acquire in these remote areas. The Cordillera Blanca of Peru is a region where dry-season water supply is increasingly stressed due to the accelerated melting of glaciers throughout the range, affecting millions of people country-wide. The alpine valleys of the Cordillera Blanca have shown potential for significant groundwater storage and discharge to valley streams, which could buffer the dry-season variability of streamflow throughout the watershed as glaciers continue to recede. Known as pampas, the clay-rich, low-relief valley bottoms are interfingered with talus deposits, providing a likely pathway for groundwater recharged at the valley edges to be stored and slowly released to the stream throughout the year by springs. Multiple geophysical methods were used to determine areas of groundwater recharge and discharge as well as aquifer geometry of the pampa system. Seismic refraction tomography, vertical electrical sounding (VES), electrical resistivity tomography (ERT), and horizontal-to-vertical spectral ratio (HVSR) seismic methods were used to determine the physical properties of the unconsolidated valley sediments, the depth to saturation, and the depth to bedrock for a representative section of the Quilcayhuanca Valley in the Cordillera Blanca. Depth to saturation and lithological boundaries were constrained by comparing geophysical results to continuous records of water levels and sediment core logs from a network of seven piezometers installed to depths of up to 6 m. Preliminary results show an average depth to bedrock for the study area of 25 m, which varies spatially along with water table depths across the valley. The conceptual model of groundwater flow and storage derived from these geophysical data will be used to inform future groundwater flow models of the area, allowing for the prediction of groundwater

Geophysical Investigations of Habitability in Ice-Covered Ocean Worlds

Science.gov (United States)

Vance, Steven D.; Panning, Mark P.; Stähler, Simon; Cammarano, Fabio; Bills, Bruce G.; Tobie, Gabriel; Kamata, Shunichi; Kedar, Sharon; Sotin, Christophe; Pike, William T.; Lorenz, Ralph; Huang, Hsin-Hua; Jackson, Jennifer M.; Banerdt, Bruce

2018-01-01

Geophysical measurements can reveal the structures and thermal states of icy ocean worlds. The interior density, temperature, sound speed, and electrical conductivity thus characterize their habitability. We explore the variability and correlation of these parameters using 1-D internal structure models. We invoke thermodynamic consistency using available thermodynamics of aqueous MgSO4, NaCl (as seawater), and NH3; pure water ice phases I, II, III, V, and VI; silicates; and any metallic core that may be present. Model results suggest, for Europa, that combinations of geophysical parameters might be used to distinguish an oxidized ocean dominated by MgSO4 from a more reduced ocean dominated by NaCl. In contrast with Jupiter's icy ocean moons, Titan and Enceladus have low-density rocky interiors, with minimal or no metallic core. The low-density rocky core of Enceladus may comprise hydrated minerals or anhydrous minerals with high porosity. Cassini gravity data for Titan indicate a high tidal potential Love number (k2>0.6), which requires a dense internal ocean (ρocean>1,200 kg m-3) and icy lithosphere thinner than 100 km. In that case, Titan may have little or no high-pressure ice, or a surprisingly deep water-rock interface more than 500 km below the surface, covered only by ice VI. Ganymede's water-rock interface is the deepest among known ocean worlds, at around 800 km. Its ocean may contain multiple phases of high-pressure ice, which will become buoyant if the ocean is sufficiently salty. Callisto's interior structure may be intermediate to those of Titan and Europa, with a water-rock interface 250 km below the surface covered by ice V but not ice VI.

Problems in nonlinear acoustics: Scattering of sound by sound, parametric receiving arrays, nonlinear effects in asymmetric sound beams and pulsed finite amplitude sound beams

Science.gov (United States)

Hamilton, Mark F.

1989-08-01

Four projects are discussed in this annual summary report, all of which involve basic research in nonlinear acoustics: Scattering of Sound by Sound, a theoretical study of two nonconlinear Gaussian beams which interact to produce sum and difference frequency sound; Parametric Receiving Arrays, a theoretical study of parametric reception in a reverberant environment; Nonlinear Effects in Asymmetric Sound Beams, a numerical study of two dimensional finite amplitude sound fields; and Pulsed Finite Amplitude Sound Beams, a numerical time domain solution of the KZK equation.

NMR multiple-echo phase-contrast blood flow imaging

International Nuclear Information System (INIS)

O'Donnell, M.

1986-01-01

A method is described for magnetic resonance imaging of fluid flow in a sample, comprising the steps of: (a) immersing the sample in a static magnetic field disposed in a first direction; (b) applying a first sequence of magnetic field gradients and radio-frequency signals to the sample to both define a slab, of the sample to be imaged, in a plane substantially orthogonal to a selected direction for which flow velocity is to be measured, and to obtain a plurality N of spin-echo response signals form that slab; (c) processing the plurality of first sequence spin-echo signals to obtain a complex value A/sub 1/(X,Y,Z) relating both the spin density rho'(X,Y,Z),... and the phase rotation phi(X,Y,Z), induced by the first sequence, for each of a selected number of sequential locations (X,Y,Z) in the sample slab; (d) applying a second sequence of magnetic field gradient and radio-frequency signals to both define the same sample slab as in step (b) and to obtain another plurality N of spin-echo response signals from that slab; (e) including a waveform in at least one of the magnetic field gradient and radio-frequency signals applied in step (d) for imparting to each of the spin-echo signal components from each slab location having a flowing material therein a phase rotation dependent upon the magnitude of the flow velocity therein in the selected direction; (f) processing the plurality of second sequence spin-echo signals to obtain a complex value A/sub 2/(X,Y,Z) relating the spin density rho'(X,Y,Z) and the imparted phase rotation of the sample material along the selected flow measurement direction for each of the sequential locations (X,Y,Z) in the sample slab; and (g) processing the complex values A/sub 1/(X,Y,Z) and A/sub 2/(X,Y,Z) for each sample location to obtain a differential phase-contrast value related to the velocity of the flowing material therein in the selected measurement direction

Numerical calculation of spin echo amplitude in pulsed NMR: effects of quadrupole interaction

International Nuclear Information System (INIS)

Sobral, R.R.

1986-01-01

The spin echo obtained by nuclear magnetic resonance, in systems which atomic nuclei interact with magnetic fields and electric field gradients, present oscillations in function of the time interval between two excitations pulses. Using the density matrix formalism, the amplitudes of these echo is calculated, analytically. In this work, echo amplitudes obtained under different excitation conditions for nuclei of different nuclear spin values are calculated. The numerical results are compared with disposable analytical solutions. Applications of this method to the case of electric field gradient without axial symmetry were studied. Within the used approximation limits, an expression for attnuation of oscillatory behaviour of echo amplitude in function of the time interval between experimentally observed pulses was obtained. (M.C.K.) [pt

PREFACE: Aerodynamic sound Aerodynamic sound

Science.gov (United States)

Akishita, Sadao

2010-02-01

The modern theory of aerodynamic sound originates from Lighthill's two papers in 1952 and 1954, as is well known. I have heard that Lighthill was motivated in writing the papers by the jet-noise emitted by the newly commercialized jet-engined airplanes at that time. The technology of aerodynamic sound is destined for environmental problems. Therefore the theory should always be applied to newly emerged public nuisances. This issue of Fluid Dynamics Research (FDR) reflects problems of environmental sound in present Japanese technology. The Japanese community studying aerodynamic sound has held an annual symposium since 29 years ago when the late Professor S Kotake and Professor S Kaji of Teikyo University organized the symposium. Most of the Japanese authors in this issue are members of the annual symposium. I should note the contribution of the two professors cited above in establishing the Japanese community of aerodynamic sound research. It is my pleasure to present the publication in this issue of ten papers discussed at the annual symposium. I would like to express many thanks to the Editorial Board of FDR for giving us the chance to contribute these papers. We have a review paper by T Suzuki on the study of jet noise, which continues to be important nowadays, and is expected to reform the theoretical model of generating mechanisms. Professor M S Howe and R S McGowan contribute an analytical paper, a valuable study in today's fluid dynamics research. They apply hydrodynamics to solve the compressible flow generated in the vocal cords of the human body. Experimental study continues to be the main methodology in aerodynamic sound, and it is expected to explore new horizons. H Fujita's study on the Aeolian tone provides a new viewpoint on major, longstanding sound problems. The paper by M Nishimura and T Goto on textile fabrics describes new technology for the effective reduction of bluff-body noise. The paper by T Sueki et al also reports new technology for the

Gradient-echo imaging of intervertebral disk degeneration and facet joint disease

International Nuclear Information System (INIS)

Berns, D.H.; Kormos, D.; Modic, M.T.; Carter, J.; Masaryk, T.J.; Ross, J.S.

1988-01-01

The purpose of this study was to evaluate the accuracy of gradient-echo, partial-flip angle images in the evaluation of components of degenerative spine disease. First, cadaveric spines were studied with plain radiographs, high-resolution CT, T1-weighted spin-echo (SE) MR images (repetition time msec/echo time msec=500/17). T2-weighted SE images (2,000/30-90), and fast low-angle shot (FLASH) images (200/10.50 0 ) before and after intradiskal injection of air (0.1-1cc). Second, lumbar spine MR images were retrospectively evaluated to compare gradient-echo and SE sequences. Results indicate that the signal intensity changes of the intervertebral disk related to degeneration were best appreciated on T2-weighted SE studies in both groups. Vacuum phenomenon and calcification were most accurately assessed with FLASH imaging (based on susceptibility changes) and CT images. SE images appeared more sensitive to adjacent marrow change. In the facet joints, CT was more accurate for changes in the subarticular bone, but FLASH images were more sensitive to change in the articular cartilage

Skew Projection of Echo-Detected EPR Spectra for Increased Sensitivity and Resolution

Science.gov (United States)

Bowman, Michael K.; Krzyaniak, Matthew D.; Cruce, Alex A.; Weber, Ralph T.

2013-01-01

The measurement of EPR spectra during pulsed EPR experiments is commonly accomplished by recording the integral of the electron spin echo as the applied magnetic field is stepped through the spectrum. This approach to echo-detected EPR spectral measurement (ED-EPR) limits sensitivity and spectral resolution and can cause gross distortions in the resulting spectra because some of the information present in the electron spin echo is discarded in such measurements. However, Fourier Transformation of echo shapes measured at a series of magnetic field values followed by skew projection onto either a magnetic field or resonance frequency axis can increase both spectral resolution and sensitivity without the need to trade one against the other. Examples of skew-projected spectra with single crystals, glasses and powders show resolution improvements as large as a factor of seven with sensitivity increases of as much as a factor of five. PMID:23644351

Artificial intelligence and dynamic systems for geophysical applications

CERN Document Server

Gvishiani, Alexei

2002-01-01

The book presents new clustering schemes, dynamical systems and pattern recognition algorithms in geophysical, geodynamical and natural hazard applications. The original mathematical technique is based on both classical and fuzzy sets models. Geophysical and natural hazard applications are mostly original. However, the artificial intelligence technique described in the book can be applied far beyond the limits of Earth science applications. The book is intended for research scientists, tutors, graduate students, scientists in geophysics and engineers

Radioactivity and geophysics

International Nuclear Information System (INIS)

Radvanyi, P.

1992-01-01

The paper recalls a few steps of the introduction of radioactivity in geophysics and astrophysics: contribution of radioelements to energy balance of the Earth, age of the Earth based on radioactive disintegration and the discovery of cosmic radiations

Review of geophysical characterization methods used at the Hanford Site

International Nuclear Information System (INIS)

GV Last; DG Horton

2000-01-01

This paper presents a review of geophysical methods used at Hanford in two parts: (1) shallow surface-based geophysical methods and (2) borehole geophysical methods. This review was not intended to be ''all encompassing'' but should represent the vast majority (>90% complete) of geophysical work conducted onsite and aimed at hazardous waste investigations in the vadose zone and/or uppermost groundwater aquifers. This review did not cover geophysical methods aimed at large-scale geologic structures or seismicity and, in particular, did not include those efforts conducted in support of the Basalt Waste Isolation Program. This review focused primarily on the more recent efforts

Geophysical data fusion for subsurface imaging

International Nuclear Information System (INIS)

Hoekstra, P.; Vandergraft, J.; Blohm, M.; Porter, D.

1993-08-01

A geophysical data fusion methodology is under development to combine data from complementary geophysical sensors and incorporate geophysical understanding to obtain three dimensional images of the subsurface. The research reported here is the first phase of a three phase project. The project focuses on the characterization of thin clay lenses (aquitards) in a highly stratified sand and clay coastal geology to depths of up to 300 feet. The sensor suite used in this work includes time-domain electromagnetic induction (TDEM) and near surface seismic techniques. During this first phase of the project, enhancements to the acquisition and processing of TDEM data were studied, by use of simulated data, to assess improvements for the detection of thin clay layers. Secondly, studies were made of the use of compressional wave and shear wave seismic reflection data by using state-of-the-art high frequency vibrator technology. Finally, a newly developed processing technique, called ''data fusion,'' was implemented to process the geophysical data, and to incorporate a mathematical model of the subsurface strata. Examples are given of the results when applied to real seismic data collected at Hanford, WA, and for simulated data based on the geology of the Savannah River Site

Foundation integrity assessment using integrated geophysical and geotechnical techniques: case study in crystalline basement complex, southwestern Nigeria

Science.gov (United States)

Olayanju, G. M.; Mogaji, K. A.; Lim, H. S.; Ojo, T. S.

2017-06-01

The determination of parameters comprising exact depth to bedrock and its lithological type, lateral changes in lithology, and detection of fractures, cracks, or faults are essential to designing formidable foundations and assessing the integrity of civil engineering structures. In this study, soil and site characterization in a typical hard rock geologic terrain in southwestern Nigeria were carried out employing integrated geophysical and geotechnical techniques to address tragedies in civil engineering infrastructural development. The deployed geophysical measurements involved running both very low frequency electromagnetic (VLF-EM) and electrical resistivity methods (dipole-dipole imaging and vertical electrical sounding (VES) techniques) along the established traverses, while the latter technique entailed conducting geological laboratory sieve analysis and Atterberg limit-index tests upon the collected soil samples in the area. The results of the geophysical measurement, based on the interpreted VLF-EM and dipole-dipole data, revealed conductive zones and linear features interpreted as fractures/faults which endanger the foundations of public infrastructures. The delineation of four distinct geoelectric layers in the area—comprised of topsoil, lateritic/clayey substratum, weathered layer, and bedrock—were based on the VES results. Strong evidence, including high degree of decomposition and fracturing of underlying bedrock revealed by the VES results, confirmed the VLF-EM and dipole-dipole results. Furthermore, values in the range of 74.2%-77.8%, 55%-62.5%, 23.4%-24.5%, 7.7%-8.2%, 19.5%-22.4%, and 31.65%-38.25% were obtained for these geotechnical parameters viz soil percentage passing 0.075 mm sieve size, liquid limit, plasticity index, linear shrinkage, natural moisture content, and plastic limit, respectively, resulting from the geotechnical analysis of the soil samples. The comparatively analyzed geophysical and geotechnical results revealed a high

Direct magnetic field estimation based on echo planar raw data.

Science.gov (United States)

Testud, Frederik; Splitthoff, Daniel Nicolas; Speck, Oliver; Hennig, Jürgen; Zaitsev, Maxim

2010-07-01

Gradient recalled echo echo planar imaging is widely used in functional magnetic resonance imaging. The fast data acquisition is, however, very sensitive to field inhomogeneities which manifest themselves as artifacts in the images. Typically used correction methods have the common deficit that the data for the correction are acquired only once at the beginning of the experiment, assuming the field inhomogeneity distribution B(0) does not change over the course of the experiment. In this paper, methods to extract the magnetic field distribution from the acquired k-space data or from the reconstructed phase image of a gradient echo planar sequence are compared and extended. A common derivation for the presented approaches provides a solid theoretical basis, enables a fair comparison and demonstrates the equivalence of the k-space and the image phase based approaches. The image phase analysis is extended here to calculate the local gradient in the readout direction and improvements are introduced to the echo shift analysis, referred to here as "k-space filtering analysis." The described methods are compared to experimentally acquired B(0) maps in phantoms and in vivo. The k-space filtering analysis presented in this work demonstrated to be the most sensitive method to detect field inhomogeneities.

Observations of fast magnetospheric echoes of artificially injected electrons above an auroral arc

International Nuclear Information System (INIS)

Wilhelm, K.; Becker, C.; Schmidt, R.

1984-04-01

Electron beam experiments using rocket-borne instrumentation have confirmed earlier observations of fast magnetospheric echoes of artificially injected energetic electrons. These experiments were jointly carried out by the University of Minnesota, the National Research Council of Canada and the Max-Planck-Institut fuer Aeronomie. A total of 234 echoes have been observed in a pitch angle range from 0 0 to 110 0 at energies of 1.87 and 3.90 keV. Out of this number, 95 echoes could unambiguously be identified with known accelerator operations at 2, 4 or 8 keV energy and highest current levels resulting in the determination of transit times of typically 400 ms. In most cases, when echoes were present in both energy channels, the higher energy electrons led the lower energy ones by approximately 50 ms. No echoes have been found in the 7.9 keV-detector channels. Adiabatic theory applied to these observations yields a reflection height of 3000 to 4000 km. The injection process is briefly discussed as the strong beam-plasma interaction that occurred near the electron accelerator appears to be instrumental in generating the source of heated electrons required for successful echo detection. Two consequences of this interaction, namely, strong energy and pitch angle diffusion and electron acceleration are illustrated with several examples. (orig.) [de

Using the Echo Nest's automatically extracted music features for a musicological purpose

DEFF Research Database (Denmark)

Andersen, Jesper Steen

2014-01-01

This paper sums up the preliminary observations and challenges encountered during my first engaging with the music intelligence company Echo Nest's automatically derived data of more than 35 million songs. The overall purpose is to investigate whether musicologists can draw benefit from Echo Nest...

EchoBASE: an integrated post-genomic database for Escherichia coli.

Science.gov (United States)

Misra, Raju V; Horler, Richard S P; Reindl, Wolfgang; Goryanin, Igor I; Thomas, Gavin H

2005-01-01

EchoBASE (http://www.ecoli-york.org) is a relational database designed to contain and manipulate information from post-genomic experiments using the model bacterium Escherichia coli K-12. Its aim is to collate information from a wide range of sources to provide clues to the functions of the approximately 1500 gene products that have no confirmed cellular function. The database is built on an enhanced annotation of the updated genome sequence of strain MG1655 and the association of experimental data with the E.coli genes and their products. Experiments that can be held within EchoBASE include proteomics studies, microarray data, protein-protein interaction data, structural data and bioinformatics studies. EchoBASE also contains annotated information on 'orphan' enzyme activities from this microbe to aid characterization of the proteins that catalyse these elusive biochemical reactions.

An integrated geophysical and hydraulic investigation to characterize a fractured-rock aquifer, Norwalk, Connecticut

Science.gov (United States)

Lane, J.W.; Williams, J.H.; Johnson, C.D.; Savino, D.M.; Haeni, F.P.

2002-01-01

The U.S. Geological Survey conducted an integrated geophysical and hydraulic investigation at the Norden Systems, Inc. site in Norwalk, Connecticut, where chlorinated solvents have contaminated a fractured-rock aquifer. Borehole, borehole-to-borehole, surface-geophysical, and hydraulic methods were used to characterize the site bedrock lithology and structure, fractures, and transmissive zone hydraulic properties. The geophysical and hydraulic methods included conventional logs, borehole imagery, borehole radar, flowmeter under ambient and stressed hydraulic conditions, and azimuthal square-array direct-current resistivity soundings. Integrated interpretation of geophysical logs at borehole and borehole-to-borehole scales indicates that the bedrock foliation strikes northwest and dips northeast, and strikes north-northeast to northeast and dips both southeast and northwest. Although steeply dipping fractures that cross-cut foliation are observed, most fractures are parallel or sub-parallel to foliation. Steeply dipping reflectors observed in the radar reflection data from three boreholes near the main building delineate a north-northeast trending feature interpreted as a fracture zone. Results of radar tomography conducted close to a suspected contaminant source area indicate that a zone of low electromagnetic (EM) velocity and high EM attenuation is present above 50 ft in depth - the region containing the highest density of fractures. Flowmeter logging was used to estimate hydraulic properties in the boreholes. Thirty-three transmissive fracture zones were identified in 11 of the boreholes. The vertical separation between transmissive zones typically is 10 to 20 ft. Open-hole and discrete-zone transmissivity was estimated from heat-pulse flowmeter data acquired under ambient and stressed conditions. The open-hole transmissivity ranges from 2 to 86 ft2/d. The estimated transmissivity of individual transmissive zones ranges from 0.4 to 68 ft2/d. Drawdown monitoring

Spin echo SPI methods for quantitative analysis of fluids in porous media.

Science.gov (United States)

Li, Linqing; Han, Hui; Balcom, Bruce J

2009-06-01

Fluid density imaging is highly desirable in a wide variety of porous media measurements. The SPRITE class of MRI methods has proven to be robust and general in their ability to generate density images in porous media, however the short encoding times required, with correspondingly high magnetic field gradient strengths and filter widths, and low flip angle RF pulses, yield sub-optimal S/N images, especially at low static field strength. This paper explores two implementations of pure phase encode spin echo 1D imaging, with application to a proposed new petroleum reservoir core analysis measurement. In the first implementation of the pulse sequence, we modify the spin echo single point imaging (SE-SPI) technique to acquire the k-space origin data point, with a near zero evolution time, from the free induction decay (FID) following a 90 degrees excitation pulse. Subsequent k-space data points are acquired by separately phase encoding individual echoes in a multi-echo acquisition. T(2) attenuation of the echo train yields an image convolution which causes blurring. The T(2) blur effect is moderate for porous media with T(2) lifetime distributions longer than 5 ms. As a robust, high S/N, and fast 1D imaging method, this method will be highly complementary to SPRITE techniques for the quantitative analysis of fluid content in porous media. In the second implementation of the SE-SPI pulse sequence, modification of the basic measurement permits fast determination of spatially resolved T(2) distributions in porous media through separately phase encoding each echo in a multi-echo CPMG pulse train. An individual T(2) weighted image may be acquired from each echo. The echo time (TE) of each T(2) weighted image may be reduced to 500 micros or less. These profiles can be fit to extract a T(2) distribution from each pixel employing a variety of standard inverse Laplace transform methods. Fluid content 1D images are produced as an essential by product of determining the

[The use of the T2-weighted turbo-spin-echo sequence in studying the neurocranium. A comparison with the conventional T2-weighted spin-echo sequence].

Science.gov (United States)

Siewert, C; Hosten, N; Felix, R

1994-07-01

T2-weighted spin-echo imaging is the standard screening procedure in MR imaging of the neurocranium. We evaluated fast spin-echo T2-weighted imaging (TT2) of the neurocranium in comparison to conventional spin-echo T2-weighted imaging (T2). Signal-to-noise and contrast-to-noise ratio of normal brain tissues (basal ganglia, grey and white matter, CSF fluid) and different pathologies were calculated. Signal-to-noise ratio and contrast-to-noise ratio were significantly higher in TT2 than in T2 (with the exception of gray-to-white matter contrast). Tissues with increased content of water protons (mobile protons) showed the highest contrast to surrounding tissues. The increased signal intensity of fat must be given due attention in fatty lesions. Because the contrast-to-noise ratio between white matter and basal ganglia is less in TT2, Parkinson patients have to be examined by conventional T2. If these limitations are taken into account, fast spin-echo T2-weighted imaging is well appropriate for MR imaging of the neurocranium, resulting in heavy T2-weighting achieved in a short acquisition time.

Field Geophysics at SAGE: Strategies for Effective Education

Science.gov (United States)

Braile, L. W.; Baldridge, W. S.; Jiracek, G. R.; Biehler, S.; Ferguson, J. F.; Pellerin, L.; McPhee, D. K.; Bedrosian, P. A.; Snelson, C. M.; Hasterok, D. P.

2011-12-01

SAGE (Summer of Applied Geophysical Experience) is a unique program of education and research in geophysical field methods for undergraduate and graduate students from any university and for professionals. The core program is held for 4 weeks each summer in New Mexico and for an additional week in the following academic year in San Diego for U.S. undergraduates supported by the NSF Research Experience for Undergraduates (REU) program. Since SAGE was initiated in 1983, 730 students have participated in the program. NSF REU funding for SAGE began in 1990 and 319 REU students have completed SAGE through 2011. The primary objectives of SAGE are to teach the major geophysical exploration methods (seismic, gravity, magnetics, electromagnetics); apply these methods to the solution of specific problems (environmental, archaeological, hydrologic, geologic structure and stratigraphy); gain experience in processing, modeling and interpretation of geophysical data; and integrate the geophysical models and interpretations with geology. Additional objectives of SAGE include conducting research on the Rio Grande rift of northern New Mexico, and providing information on geophysics careers and professional development experiences to SAGE participants. Successful education, field and research strategies that we have implemented over the years include: 1. learn by doing; 2. mix lecture/discussion, field work, data processing and analysis, modeling and interpretation, and presentation of results; 3. a two-tier team approach - method/technique oriented teams and interpretation/integration teams (where each team includes persons representing different methods), provides focus, in-depth study, opportunity for innovation, and promotes teamwork and a multi-disciplinary approach; 4. emphasis on presentations/reports - each team (and all team members) make presentation, each student completes a written report; 5. experiment design discussion - students help design field program and consider

Shallow radar (SHARAD) sounding observations of the Medusae Fossae Formation, Mars

Science.gov (United States)

Carter, L.M.; Campbell, B.A.; Watters, T.R.; Phillips, R.J.; Putzig, N.E.; Safaeinili, A.; Plaut, J.J.; Okubo, C.H.; Egan, A.F.; Seu, R.; Biccari, D.; Orosei, R.

2009-01-01

The SHARAD (shallow radar) sounding radar on the Mars Reconnaissance Orbiter detects subsurface reflections in the eastern and western parts of the Medusae Fossae Formation (MFF). The radar waves penetrate up to 580 m of the MFF and detect clear subsurface interfaces in two locations: west MFF between 150 and 155?? E and east MFF between 209 and 213?? E. Analysis of SHARAD radargrams suggests that the real part of the permittivity is ???3.0, which falls within the range of permittivity values inferred from MARSIS data for thicker parts of the MFF. The SHARAD data cannot uniquely determine the composition of the MFF material, but the low permittivity implies that the upper few hundred meters of the MFF material has a high porosity. One possibility is that the MFF is comprised of low-density welded or interlocked pyroclastic deposits that are capable of sustaining the steep-sided yardangs and ridges seen in imagery. The SHARAD surface echo power across the MFF is low relative to typical martian plains, and completely disappears in parts of the east MFF that correspond to the radar-dark Stealth region. These areas are extremely rough at centimeter to meter scales, and the lack of echo power is most likely due to a combination of surface roughness and a low near-surface permittivity that reduces the echo strength from any locally flat regions. There is also no radar evidence for internal layering in any of the SHARAD data for the MFF, despite the fact that tens-of-meters scale layering is apparent in infrared and visible wavelength images of nearby areas. These interfaces may not be detected in SHARAD data if their permittivity contrasts are low, or if the layers are discontinuous. The lack of closely spaced internal radar reflectors suggests that the MFF is not an equatorial analog to the current martian polar deposits, which show clear evidence of multiple internal layers in SHARAD data. ?? 2008 Elsevier Inc.

Mechanisms of echolocation in bats; Komori no echolocation

Energy Technology Data Exchange (ETDEWEB)

Kawasaki, M.

1999-12-05

This paper summarizes echolocation in bats. Bats hear reflected echo of ultrasonic waves they generate themselves, enabling them to fly freely in darkness or catch preys. Bats generate wave sounds of large volume at high frequencies suitable for catching preys, and can detect distance from objects, shapes of the objects, and relative velocity with that of the preys. Considering in terms of physics, bats detect the distance from delay in echo reflection, the size from echo intensity, and the relative velocity from the Doppler effect. The static sound generated ten times per second contains CF sound (for detecting a target) and FM sound (for measuring the distance), each composed of four frequency components. The animal's brain unifies and calculates signals from hair cells in the cochleae to acquire items of information including distance. Neurons exist in the acoustic sense field in brain cortex to generate impulses only when the static sound is coupled with the echo. Response properties of these neurons are formed in the brain via complex processing based on acoustic information caught by the hair cells. (NEDO)

Dissecting a Light Echo

Science.gov (United States)

2008-01-01

[figure removed for brevity, see original site] Click on image for audio animation This animation illustrates how a light echo works, and how an optical illusion of material moving outward is created. A light echo occurs when a star explodes, acting like a cosmic flashbulb. The light from this explosion zips through nearby dust clumps, illuminating and heating them up slightly. This brief period of warming causes them to glow in infrared, like a chain of Christmas bulbs lighting up one by one. The animation starts by showing the explosion of a star, which results in a flash of light that moves outward in all directions. The direction of our line of sight from Earth is indicated by the blue arrow. When the light flash reaches surrounding dust, shown here as three dark clouds, the dust is heated up, creating infrared light that begins to travel toward Earth (indicated by the red arrows). Dust closest to the explosion lights up first, while the explosion's shock wave takes longer to reach more distant material. This results in light from different parts of the cloud reaching Earth at different times, creating the illusion of motion over time. As the animation shows, the inclination of the cloud toward our line of sight can result in the material seeming to move both away from and toward the central star.

Simultaneous pH-sensitive and oxygen-sensitive MRI of human gliomas at 3 T using multi-echo amine proton chemical exchange saturation transfer spin-and-gradient echo echo-planar imaging (CEST-SAGE-EPI).

Science.gov (United States)

Harris, Robert J; Yao, Jingwen; Chakhoyan, Ararat; Raymond, Catalina; Leu, Kevin; Liau, Linda M; Nghiemphu, Phioanh L; Lai, Albert; Salamon, Noriko; Pope, Whitney B; Cloughesy, Timothy F; Ellingson, Benjamin M

2018-04-06

To introduce a new pH-sensitive and oxygen-sensitive MRI technique using amine proton CEST echo spin-and-gradient echo (SAGE) EPI (CEST-SAGE-EPI). pH-weighting was obtained using CEST estimations of magnetization transfer ratio asymmetry (MTR asym ) at 3 ppm, and oxygen-weighting was obtained using R2' measurements. Glutamine concentration, pH, and relaxation rates were varied in phantoms to validate simulations and estimate relaxation rates. The values of MTR asym and R2' in normal-appearing white matter, T 2 hyperintensity, contrast enhancement, and macroscopic necrosis were measured in 47 gliomas. Simulation and phantom results confirmed an increase in MTR asym with decreasing pH. The CEST-SAGE-EPI estimates of R 2 , R2*, and R2' varied linearly with gadolinium diethylenetriamine penta-acetic acid concentration (R 2  = 6.2 mM -1 ·sec -1 and R2* = 6.9 mM -1 ·sec -1 ). The CEST-SAGE-EPI and Carr-Purcell-Meiboom-Gill estimates of R 2 (R 2  = 0.9943) and multi-echo gradient-echo estimates of R2* (R 2  = 0.9727) were highly correlated. T 2 lesions had lower R2' and higher MTR asym compared with normal-appearing white matter, suggesting lower hypoxia and high acidity, whereas contrast-enhancement tumor regions had elevated R2' and MTR asym , indicating high hypoxia and acidity. The CEST-SAGE-EPI technique provides simultaneous pH-sensitive and oxygen-sensitive image contrasts for evaluation of the brain tumor microenvironment. Advantages include fast whole-brain acquisition, in-line B 0 correction, and simultaneous estimation of CEST effects, R 2 , R2*, and R2' at 3 T. © 2018 International Society for Magnetic Resonance in Medicine.

The novel echo-guided ProGlide technique during percutaneous transfemoral transcatheter aortic valve implantation.

Science.gov (United States)

Honda, Yohsuke; Araki, Motoharu; Yamawaki, Masahiro; Tokuda, Takahiro; Tsutumi, Masakazu; Mori, Shinsuke; Sakamoto, Yasunari; Kobayashi, Norihiro; Hirano, Keisuke; Ito, Yoshiaki

2018-04-01

The aim of this study was to assess clinical benefit of the Echo-guided ProGlide technique in patients undergoing percutaneous transfemoral transcatheter aortic valve implantation (TF-TAVI). The efficacy of the Echo-guided ProGlide technique during percutaneous TF-TAVI was not previously clarified. A total of 121 consecutive patients who underwent percutaneous TF-TAVI at our institution between February 2014 and July 2017 were enrolled in this study. According to the introduction of this novel technique in March 2016, patients were divided into two groups (echo-guided group who underwent TAVI from March 2016 to July 2017, n = 63; not echo-guided group who underwent TAVI from February 2014 to February 2016, n = 58). The incidence of major vascular complications, defined per the Valve Academic Research Consortium-2 criteria, and ProGlide complications including acute femoral artery stenosis or occlusion and bleeding requiring any intervention. The incidence of major vascular complication and ProGlide complication were significantly lower in the echo-guided group than in not echo-guided group (1.6% vs 17.2%, P guided ProGlide technique was independently associated with prevention of ProGlide complications (odds ratio, 0.11; 95% confidential interval, 0.01-0.76; P = 0.03). This novel Echo-guided ProGlide technique was associated with a lower rate of major vascular complications, particularly ProGlide complications during percutaneous TF-TAVI. © 2017, Wiley Periodicals, Inc.

Geophysical Methods for Investigating Ground-Water Recharge

Science.gov (United States)

Ferre, Ty P.A.; Binley, Andrew M.; Blasch, Kyle W.; Callegary, James B.; Crawford, Steven M.; Fink, James B.; Flint, Alan L.; Flint, Lorraine E.; Hoffmann, John P.; Izbicki, John A.; Levitt, Marc T.; Pool, Donald R.; Scanlon, Bridget R.

2007-01-01

While numerical modeling has revolutionized our understanding of basin-scale hydrologic processes, such models rely almost exclusively on traditional measurements?rainfall, streamflow, and water-table elevations?for calibration and testing. Model calibration provides initial estimates of ground-water recharge. Calibrated models are important yet crude tools for addressing questions about the spatial and temporal distribution of recharge. An inverse approach to recharge estimation is taken of necessity, due to inherent difficulties in making direct measurements of flow across the water table. Difficulties arise because recharging fluxes are typically small, even in humid regions, and because the location of the water table changes with time. Deep water tables in arid and semiarid regions make recharge monitoring especially difficult. Nevertheless, recharge monitoring must advance in order to improve assessments of ground-water recharge. Improved characterization of basin-scale recharge is critical for informed water-resources management. Difficulties in directly measuring recharge have prompted many efforts to develop indirect methods. The mass-balance approach of estimating recharge as the residual of generally much larger terms has persisted despite the use of increasing complex and finely gridded large-scale hydrologic models. Geophysical data pertaining to recharge rates, timing, and patterns have the potential to substantially improve modeling efforts by providing information on boundary conditions, by constraining model inputs, by testing simplifying assumptions, and by identifying the spatial and temporal resolutions needed to predict recharge to a specified tolerance in space and in time. Moreover, under certain conditions, geophysical measurements can yield direct estimates of recharge rates or changes in water storage, largely eliminating the need for indirect measures of recharge. This appendix presents an overview of physically based, geophysical methods

Investigations on resolution enhancement in EPR by means of electron spin echoes

International Nuclear Information System (INIS)

Merks, R.P.J.

1979-01-01

The electron spin echo technique has been applied in four types of experiments: the measurement of electric field induced shifts of the EPR line; the detection of electron spin echo ENDOR; a relaxation measurement and the measurement of hyperfine interactions via the nuclear modulation effect. (Auth.)

Review of geophysical characterization methods used at the Hanford Site

Energy Technology Data Exchange (ETDEWEB)

GV Last; DG Horton

2000-03-23

This paper presents a review of geophysical methods used at Hanford in two parts: (1) shallow surface-based geophysical methods and (2) borehole geophysical methods. This review was not intended to be ``all encompassing'' but should represent the vast majority (>90% complete) of geophysical work conducted onsite and aimed at hazardous waste investigations in the vadose zone and/or uppermost groundwater aquifers. This review did not cover geophysical methods aimed at large-scale geologic structures or seismicity and, in particular, did not include those efforts conducted in support of the Basalt Waste Isolation Program. This review focused primarily on the more recent efforts.

Solar Wind Monitor--A School Geophysics Project

Science.gov (United States)

Robinson, Ian

2018-01-01

Described is an established geophysics project to construct a solar wind monitor based on a nT resolution fluxgate magnetometer. Low-cost and appropriate from school to university level it incorporates elements of astrophysics, geophysics, electronics, programming, computer networking and signal processing. The system monitors the earth's field in…

Scattered-Light Echoes from the Historical Galactic Supernovae Cassiopeia A and Tycho (SN 1572)

Energy Technology Data Exchange (ETDEWEB)

Rest, A; Welch, D L; Suntzeff, N B; Oaster, L; Lanning, H; Olsen, K; Smith, R C; Becker, A C; Bergmann, M; Challis, P; Clocchiatti, A; Cook, K H; Damke, G; Garg, A; Huber, M E; Matheson, T; Minniti, D; Prieto, J L; Wood-Vasey, W M

2008-05-06

We report the discovery of an extensive system of scattered light echo arclets associated with the recent supernovae in the local neighborhood of the Milky Way: Tycho (SN 1572) and Cassiopeia A. Existing work suggests that the Tycho SN was a thermonuclear explosion while the Cas A supernova was a core collapse explosion. Precise classifications according to modern nomenclature require spectra of the outburst light. In the case of ancient SNe, this can only be done with spectroscopy of their light echo, where the discovery of the light echoes from the outburst light is the first step. Adjacent light echo positions suggest that Cas A and Tycho may share common scattering dust structures. If so, it is possible to measure precise distances between historical Galactic supernovae. On-going surveys that alert on the development of bright scattered-light echo features have the potential to reveal detailed spectroscopic information for many recent Galactic supernovae, both directly visible and obscured by dust in the Galactic plane.

Scattered-Light Echoes from the Historical Galactic Supernovae Cassiopeia A and Tycho (SN 1572)

International Nuclear Information System (INIS)

Rest, A.; Welch, D.L.; Suntzeff, N.B.; Oaster, L.; Lanning, H.; Olsen, K.; Smith, R.C.; Becker, A.C.; Bergmann, M.; Challis, P.; Clocchiatti, A.; Cook, K.H.; Damke, G.; Garg, A.; Huber, M.E.; Matheson, T.; Minniti, D.; Prieto, J.L.; Wood-Vasey, W.M.

2008-01-01

We report the discovery of an extensive system of scattered light echo arclets associated with the recent supernovae in the local neighborhood of the Milky Way: Tycho (SN 1572) and Cassiopeia A. Existing work suggests that the Tycho SN was a thermonuclear explosion while the Cas A supernova was a core collapse explosion. Precise classifications according to modern nomenclature require spectra of the outburst light. In the case of ancient SNe, this can only be done with spectroscopy of their light echo, where the discovery of the light echoes from the outburst light is the first step. Adjacent light echo positions suggest that Cas A and Tycho may share common scattering dust structures. If so, it is possible to measure precise distances between historical Galactic supernovae. On-going surveys that alert on the development of bright scattered-light echo features have the potential to reveal detailed spectroscopic information for many recent Galactic supernovae, both directly visible and obscured by dust in the Galactic plane

Fast-gradient-echo variable-flip-angle imaging of the cervical spine

International Nuclear Information System (INIS)

Van Dyke, C.W.; Ross, J.S.; Masaryk, T.J.; Tkach, J.; Beale, S.; Hueftle, M.G.; Kaufman, B.; Modic, M.T.

1987-01-01

Two hundred consecutive patients were studied with 4-mm sagittal and axial T1-weighted images and gradient echo sequences with 6-msec or 13-msec echo time (TE) and 10 0 or 60 0 flip angles to evaluate cervical extradural disease. Images were independently evaluated for contrast behavior and anatomy, then directly compared for conspicuity of lesions. FLASH sequences produced better conspicuity of disease in half the imaging time. T1-weighted spin-echo (SE) sequences were more sensitive to marrow changes and intradural disease. Shorter TEs produced overall image improvement and reduced susceptibility effects. A fast and sensitive cervical examination combines sagittal T1-weighted SE with sagittal and axial FLASH 10 0 sequences with 6-msec TE

A comparison between fast and conventional spin-echo in the detection of multiple sclerosis lesions

International Nuclear Information System (INIS)

Thorpe, J.W.; Halpin, S.F.; MacManus, D.G.; Barker, G.J.; Kendall, B.E.; Miller, D.H.

1994-01-01

Long repetition time (TR) spin-echo (SE) with T 2 - or proton density weighting is the sequence of choice to detect the brain lesions of multiple sclerosis (MS). Fast spin-echo (FSE) permits the generation of T 2 -weighted images with similar contrast to SE but in a fraction of the time. We compared the sensitivity of FSE and SE in the detection of the brain lesions of MS. Six patients with clinically definite MS underwent brain imaging with both dual echo (long TR, long and short echo time (TE) SE and dual echo FSE. The SE and FSE images were first reviewed independently and then compared. A total of 404 lesions was detected on SE and 398 on FSE. Slightly more periventricular lesions were detected using SE than FSE (145 vs 127), whereas more posterior cranial fossa lesions were detected by FSE (77 vs 57). With both SE and FSE the short TE images revealed more lesions than the long echo. These results suggest that FSE could replace SE as the long TR sequence of choice in the investigation of MS. (orig.)

Pre-ejection period by radial artery tonometry supplements echo doppler findings during biventricular pacemaker optimization

Directory of Open Access Journals (Sweden)

Qamruddin Salima

2011-07-01

Full Text Available Abstract Background Biventricular (Biv pacemaker echo optimization has been shown to improve cardiac output however is not routinely used due to its complexity. We investigated the role of a simple method involving computerized pre-ejection time (PEP assessment by radial artery tonometry in guiding Biv pacemaker optimization. Methods Blinded echo and radial artery tonometry were performed simultaneously in 37 patients, age 69.1 ± 12.8 years, left ventricular (LV ejection fraction (EF 33 ± 10%, during Biv pacemaker optimization. Effect of optimization on echo derived velocity time integral (VTI, ejection time (ET, myocardial performance index (MPI, radial artery tonometry derived PEP and echo-radial artery tonometry derived PEP/VTI and PEP/ET indices was evaluated. Results Significant improvement post optimization was achieved in LV ET (286.9 ± 37.3 to 299 ± 34.6 ms, p Conclusion An acute shortening of PEP by radial artery tonometry occurs post Biv pacemaker optimization and correlates with improvement in hemodynamics by echo Doppler and may provide a cost-efficient approach to assist with Biv pacemaker echo optimization.

Application of nuclear-geophysical methods to reserves estimation

International Nuclear Information System (INIS)

Bessonova, T.B.; Karpenko, I.A.

1980-01-01

On the basis of the analysis of reports dealing with calculations of mineral reserves considered are shortcomings in using nuclear-geophysical methods and in assessment of the reliability of geophysical sampling. For increasing efficiency of nuclear-geophysical investigations while prospecting ore deposits, it is advisable to introduce them widely instead of traditional geological sampling methods. For this purpose it is necessary to increase sensitivity and accuracy of radioactivity logging methods, to provide determination of certain elements in ores by these methods

Groundwater geophysics. A tool for hydrology. 2. ed.

Energy Technology Data Exchange (ETDEWEB)

Kirsch, Reinhard (ed.) [Landesamt fuer Natur und Umwelt, Flintbek (Germany). Abt. Geologie/Boden

2009-07-01

Access to clean water is a human right and a basic requirement for economic development. The safest kind of water supply is the use of groundwater. Since groundwater normally has a natural protection against pollution by the covering layers, only minor water treatment is required. Detailed knowledge on the extent, hydraulic properties, and vulnerability of groundwater reservoirs is necessary to enable a sustainable use of the resources. This book addresses students and professionals in Geophysics and Hydrogeology. The aim of the authors is to demonstrate the application of geophysical techniques to provide a database for hydrogeological decisions like drillhole positioning or action plans for groundwater protection. Physical fundamentals and technical aspects of modern geophysical reconnaissance methods are discussed in the first part of the book. Beside 'classical' techniques like seismic, resistivity methods, radar, magnetic, and gravity methods emphasis is on relatively new techniques like complex geoelectric, radiomagnetotellurics, vertical groundwater flow determination, or nuclear magnetic resonance. An overview of direct push techniques is given which can fill the gap between surface and borehole geophysics. The applications of these techniques for hydrogeological purposes are illustrated in the second part of the book. The investigation of pore aquifers is demonstrated by case histories from Denmark, Germany, and Egypt. Examples for the mapping of fracture zone and karst aquifers as well as for saltwater intrusions leading to reduced groundwater quality are shown. The assessment of hydraulic conductivities of aquifers by geophysical techniques is discussed with respect to the use of porosity - hydraulic conductivity relations and to geophysical techniques like NMR or SIP which are sensitive to the effective porosity of the material. The classification of groundwater protective layers for vulnerability maps as required by the EU water framework

Contrast-enhanced MR imaging of metastatic brain tumor at 3 Tesla. Utility of T1-weighted SPACE compared with 2D spin echo and 3D gradient echo sequence

International Nuclear Information System (INIS)

Komada, Tomohiro; Naganawa, Shinji; Ogawa, Hiroshi

2008-01-01

We evaluated the newly developed whole-brain, isotropic, 3-dimensional turbo spin-echo imaging with variable flip angle echo train (SPACE) for contrast-enhanced T 1 -weighted imaging in detecting brain metastases at 3 tesla (T). Twenty-two patients with suspected brain metastases underwent postcontrast study with SPACE, magnetization-prepared rapid gradient-echo (MP-RAGE), and 2-dimensional T 1 -weighted spin echo (2D-SE) imaging at 3 T. We quantitatively compared SPACE, MP-RAGE, and 2D-SE images by using signal-to-noise ratios (SNRs) for gray matter (GM) and white matter (WM) and contrast-to-noise ratios (CNRs) for GM-to-WM, lesion-to-GM, and lesion-to-WM. Two blinded radiologists evaluated the detection of brain metastases by segment-by-segment analysis and continuously-distributed test. The CNR between GM and WM was significantly higher on MP-RAGE images than on SPACE images (P 1 -weighted imaging. (author)

NMR polarization echoes in a nematic liquid crystal

Science.gov (United States)

Levstein, Patricia R.; Chattah, Ana K.; Pastawski, Horacio M.; Raya, Jésus; Hirschinger, Jérôme

2004-10-01

We have modified the polarization echo (PE) sequence through the incorporation of Lee-Goldburg cross polarization steps to quench the 1H-1H dipolar dynamics. In this way, the 13C becomes an ideal local probe to inject and detect polarization in the proton system. This improvement made possible the observation of the local polarization P00(t) and polarization echoes in the interphenyl proton of the liquid crystal N-(4-methoxybenzylidene)-4-butylaniline. The decay of P00(t) was well fitted to an exponential law with a characteristic time τC≈310 μs. The hierarchy of the intramolecular dipolar couplings determines a dynamical bottleneck that justifies the use of the Fermi Golden Rule to obtain a spectral density consistent with the structural parameters. The time evolution of P00(t) was reversed by the PE sequence generating echoes at the time expected by the scaling of the dipolar Hamiltonian. This indicates that the reversible 1H-1H dipolar interaction is the main contribution to the local polarization decrease and that the exponential decay for P00(t) does not imply irreversibility. The attenuation of the echoes follows a Gaussian law with a characteristic time τφ≈527 μs. The shape and magnitude of the characteristic time of the PE decay suggest that it is dominated by the unperturbed homonuclear dipolar Hamiltonian. This means that τφ is an intrinsic property of the dipolar coupled network and not of other degrees of freedom. In this case, one cannot unambiguously identify the mechanism that produces the decoherence of the dipolar order. This is because even weak interactions are able to break the fragile multiple coherences originated on the dipolar evolution, hindering its reversal. Other schemes to investigate these underlying mechanisms are proposed.

Realtime identification of the propagation direction of received echoes in long range ultrasonic testing

International Nuclear Information System (INIS)

Choi, Myoung Seon; Heo, Won Nyoung

2013-01-01

In long range ultrasonic testing, a phased array probe composed of multiple identical transducers with an uniform interval of one quarter wavelength is usually used for the transmission or reception directivity control. This paper shows that the propagation directions of individual echoes can be identified in real time by displaying the inputs of a process for summing the constitution reception signals after compensating the phase difference due to the transducer interval, together with the output of the process. A constructive interference of the constitution echoes indicates a forward direction echo propagating along an intended direction while a destructive interference implies a reverse direction echo propagating along the direction opposite to the intended one

Normal range of hepatic fat fraction on dual- and triple-echo fat quantification MR in children.

Science.gov (United States)

Shin, Hyun Joo; Kim, Hyun Gi; Kim, Myung-Joon; Koh, Hong; Kim, Ha Yan; Roh, Yun Ho; Lee, Mi-Jung

2015-01-01

To evaluate hepatic fat fraction on dual- and triple-echo gradient-recalled echo MRI sequences in healthy children. We retrospectively reviewed the records of children in a medical check-up clinic from May 2012 to November 2013. We excluded children with abnormal laboratory findings or those who were overweight. Hepatic fat fraction was measured on dual- and triple-echo sequences using 3T MRI. We compared fat fractions using the Wilcoxon signed rank test and the Bland-Altman 95% limits of agreement. The correlation between fat fractions and clinical and laboratory findings was evaluated using Spearman's correlation test, and the cut-off values of fat fractions for diagnosing fatty liver were obtained from reference intervals. In 54 children (M:F = 26:28; 5-15 years; mean 9 years), the dual fat fraction (0.1-8.0%; median 1.6%) was not different from the triple fat fraction (0.4-6.5%; median 2.7%) (p = 0.010). The dual- and triple-echo fat fractions showed good agreement using a Bland-Altman plot (-0.6 ± 2.8%). Eight children (14.8%) on dual-echo sequences and six (11.1%) on triple-echo sequences had greater than 5% fat fraction. From these children, six out of eight children on dual-echo sequences and four out of six children on triple-echo sequences had a 5-6% hepatic fat fraction. When using a cut-off value of a 6% fat fraction derived from a reference interval, only 3.7% of children were diagnosed with fatty liver. There was no significant correlation between clinical and laboratory findings with dual and triple-echo fat fractions. Dual fat fraction was not different from triple fat fraction. We suggest a cut-off value of a 6% fat fraction is more appropriate for diagnosing fatty liver on both dual- and triple-echo sequences in children.

Four-wave neutron-resonance spin echo

International Nuclear Information System (INIS)

Grigoriev, S.V.; Kraan, W.H.; Rekveldt, M.Th.

2004-01-01

We develop a technique of scattering from many-body systems. It is based on the principle of the neutron spin echo (SE), where a neutron wave in the magnetic field splits into two waves, which are separated in space or in time after propagation in this field. The neutron thus prepared as a probe passes through the sample to test its properties on a space R or time t scale. This separation in space or in time can be measured using coherence of these two waves as a phase shift φ between them. These two waves are collected or focused and compensated by the SE technique in order to compare their phases after interaction with the sample. In this way one studies interference between these waves and thus can directly measure the pair-correlation function in space or in time. Instead of two-wave SE we propose to realize the four-wave neutron-resonance spin-echo (NRSE). In our experiments, spin precession produced by a couple of the neutron-resonance coils in one arm is compensated by an identical couple of other NR coils in a second arm of a spin-echo machine. The neutron spin-flip probability ρ in the resonance coils is a key parameter of the NRSE arm. The limiting cases, ρ=0 and ρ=1, provide, in quantum terms, a two-level-two-wave k splitting of the neutron and result in the separation of the split waves into two different lengths in space (R 1 ,R 2 ) or in time (t 1 ,t 2 ). These two cases correspond to Larmor precession with phase φ 1 in the static magnetic fields of the NR flippers or to NRSE precession with φ 2 , respectively. The intermediate case, 0 1 ,R 2 ,R 3 ) or in time (t 1 ,t 2 ,t 3 ). The interference of each pair of waves after compensation results in three different echos with phases φ 1 , φ 2 , and φ 3 =(φ 1 +φ 2 )/2. Focusing or compensating all four waves into a single point of the phase-of-waves diagram produces quantum interference of all newly created waves. This task of focusing is experimentally performed. Different options for the

Geophysical background and as-built target characteristics

International Nuclear Information System (INIS)

Allen, J.W.

1994-09-01

The US Department of Energy (DOE) Grand Junction Projects Office (GJPO) has provided a facility for DOE, other Government agencies, and the private sector to evaluate and document the utility of specific geophysical measurement techniques for detecting and defining cultural and environmental targets. This facility is the Rabbit Valley Geophysics Performance Evaluation Range (GPER). Geophysical surveys prior to the fiscal year (FY) 1994 construction of new test cells showed the primary test area to be relatively homogeneous and free from natural or man-made artifacts, which would generate spurious responses in performance evaluation data. Construction of nine new cell areas in Rabbit Valley was completed in June 1994 and resulted in the emplacement of approximately 150 discrete targets selected for their physical and electrical properties. These targets and their geophysical environment provide a broad range of performance evaluation parameters from ''very easy to detect'' to ''challenging to the most advanced systems.'' Use of nonintrusive investigative techniques represents a significant improvement over intrusive characterization methods, such as drilling or excavation, because there is no danger of exposing personnel to possible hazardous materials and no risk of releasing or spreading contamination through the characterization activity. Nonintrusive geophysical techniques provide the ability to infer near-surface structure and waste characteristics from measurements of physical properties associated with those targets

Looking Forward to the electronic Geophysical Year

Science.gov (United States)

Kamide, Y.; Baker, D. N.; Thompson, B.; Barton, C.; Kihn, E.

2004-12-01

During the International Geophysical Year (1957-1958), member countries established many new capabilities pursuing the major IGY objectives of collecting geophysical data as widely as possible and providing free access to these data for all scientists around the globe. A key achievement of the IGY was the establishment of a worldwide system of data centers and physical observatories. The worldwide scientific community has now endorsed and is promoting an electronic Geophysical Year (eGY) initiative. The proposed eGY concept would both commemorate the 50th anniversary of the IGY in 2007-2008 and would provide a forward impetus to geophysics in the 21st century, similar to that provide by the IGY fifty years ago. The eGY concept advocates the establishment of a series of virtual geophysical observatories now being deployed in cyberspace. We discuss plans to aggregate measurements into a readily accessible database along with analysis, visualization, and display tools that will make information available and useful to the scientific community, to the user community, and to the general public. We are examining the possibilities for near-realtime acquisition of data and utilization of forecast tools in order to provide users with advanced space weather capabilities. This program will provide powerful tools for education and public outreach concerning the connected Sun-Earth System.

Imagining Sound

DEFF Research Database (Denmark)

Grimshaw, Mark; Garner, Tom Alexander

2014-01-01

We make the case in this essay that sound that is imagined is both a perception and as much a sound as that perceived through external stimulation. To argue this, we look at the evidence from auditory science, neuroscience, and philosophy, briefly present some new conceptual thinking on sound...... that accounts for this view, and then use this to look at what the future might hold in the context of imagining sound and developing technology....

Rapid geophysical surveyor

International Nuclear Information System (INIS)

Roybal, L.G.; Carpenter, G.S.; Josten, N.E.

1993-01-01

The Rapid Geophysical Surveyor (RGS) is a system designed to rapidly and economically collect closely-spaced geophysical data used for characterization of Department of Energy (DOE) waste sites. Geophysical surveys of waste sites are an important first step in the remediation and closure of these sites; especially older sties where historical records are inaccurate and survey benchmarks have changed due to refinements in coordinate controls and datum changes. Closely-spaced data are required to adequately differentiate pits, trenches, and soil vault rows whose edges may be only a few feet from each other. A prototype vehicle designed to collect magnetic field data was built at the Idaho national Engineering Laboratory (INEL) during the summer of 1992. The RGS was one of several projects funded by the Buried Waste Integrated Demonstration (BWID) program. This vehicle was demonstrated at the Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex (RWMC) on the INEL in September of 1992. Magnetic data were collected over two areas in the SDA, with a total survey area of about 1.7 acres. Data were collected at a nominal density of 2 1/2 inches along survey lines spaced 1 foot apart. Over 350,000 data points were collected over a 6 day period corresponding to about 185 man-days using conventional ground survey techniques. This report documents the design and demonstration of the RGS concept including the presentation of magnetic data collected at the SDA. The surveys were able to show pit and trench boundaries and determine details of their spatial orientation never before achieved

Kinematic, dynamic, and thermodynamic impacts of hook-echo hydrometeors, including explorations into the utilization of polarimetric radar data

Science.gov (United States)

Askelson, Mark Anthony

Recent studies have revealed that the thermodynamic properties of the rear flank downdraft (RFD) may dictate whether or not a supercell becomes tornadic. Since hydrometeors are thought to be an important driving force for the RFD, it is postulated that they may be important to its thermodynamic properties and, possibly, to tornadogenesis. The role hook-echo hydrometeors play in driving RFDs is investigated by estimating hook-echo hydrometeor types and amounts from polarimetric radar data and by using that information to drive a relatively simple downdraft model. Soundings for the individual cases are used to initialize the downdraft model in order to replicate the environments of the storms as closely as possible. Since this effort and others like it require the quantitative utilization of radar data, issues pertaining to this are explored. In addition to analyses of coordinate transformation equations and an innovative objective analysis technique for weather radar data, the difficult problem of response functions for arbitrary weight functions and data distributions was considered. A novel approach to this problem revealed that the local response function for distance dependent weighted averaging schemes is the complex conjugate of the normalized Fourier transform of the effective weight function. This facilitates new research avenues, especially regarding analyses of irregularly spaced data. Simulations of hydrometeor driven RFDs show that hydrometeor fields inferred from radar data are able to drive significant downdrafts without the influence of vertical perturbation pressure gradients. Moreover, they reveal that above the boundary layer supercell environments are relatively resistant to downdrafts whereas within the boundary layer they are generally supportive of downdrafts. It appears that in many supercell environments relatively large hail (≥1 cm in diameter) or vertical perturbation pressure gradients may be needed to drive deep midlevel downdrafts that

Development of Geophysical Ideas and Institutions in Ottoman Empire

Science.gov (United States)

Ozcep, Ferhat; Ozcep, Tazegul

2015-04-01

In Anatolia, the history of geophysical sciences may go back to antiquity (600 BC), namely the period when Thales lived in Magnesia (Asia Minor). In the modern sense, geophysics started with geomagnetic works in the 1600s. The period between 1600 and 1800 includes the measurement of magnetic declination, inclination and magnetic field strength. Before these years, there is a little information, such as how to use a compass, in the Kitab-i Bahriye (the Book of Navigation) of Piri Reis, who is one of the most important mariners of the Ottoman Empire. However, this may not mean that magnetic declination was generally understood. The first scientific book relating to geophysics is the book Fuyuzat-i Miknatissiye that was translated by Ibrahim Müteferrika and printed in 1731. The subject of this book is earth's magnetism. There is also information concerning geophysics in the book Cihannuma (Universal Geography) that was written by Katip Celebi and in the book Marifetname written by Ibrahim Hakki Erzurumlu, but these books are only partly geophysical books. In Istanbul the year 1868 is one of the most important for geophysical sciences because an observatory called Rasathane-i Amire was installed in the Pera region of this city. At this observatory the first systematic geophysical observations such as meteorological, seismological and even gravimetrical were made. There have been meteorological records in Anatolia since 1839. These are records of atmospheric temperature, pressure and humidity. In the Ottoman Empire, the science of geophysics is considered as one of the natural sciences along with astronomy, mineralogy, geology, etc., and these sciences are included as a part of physics and chemistry.

Meteor head echo polarization at 930 MHz studied with the EISCAT UHF HPLA radar

Directory of Open Access Journals (Sweden)

G. Wannberg

2011-06-01

Full Text Available The polarization characteristics of 930-MHz meteor head echoes have been studied for the first time, using data obtained in a series of radar measurements carried out with the tristatic EISCAT UHF high power, large aperture (HPLA radar system in October 2009. An analysis of 44 tri-static head echo events shows that the polarization of the echo signal recorded by the Kiruna receiver often fluctuates strongly on time scales of tens of microseconds, illustrating that the scattering process is essentially stochastic. On longer timescales (> milliseconds, more than 90 % of the recorded events show an average polarization signature that is independent of meteor direction of arrival and echo strength and equal to that of an incoherent-scatter return from underdense plasma filling the tristatic observation volume. This shows that the head echo plasma targets scatter isotropically, which in turn implies that they are much smaller than the 33-cm wavelength and close to spherically symmetric, in very good agreement with results from a previous EISCAT UHF study of the head echo RCS/meteor angle-of-incidence relationship. Significant polarization is present in only three events with unique target trajectories. These all show a larger effective target cross section transverse to the trajectory than parallel to it. We propose that the observed polarization may be a signature of a transverse charge separation plasma resonance in the region immediately behind the meteor head, similar to the resonance effects previously discussed in connection with meteor trail echoes by Herlofson, Billam and Browne, Jones and Jones and others.

Electron Dropout Echoes Induced by Interplanetary Shock: A Statistical Study

Science.gov (United States)

Liu, Z.; Zong, Q.; Hao, Y.; Zhou, X.; Ma, X.; Liu, Y.

2017-12-01

"Electron dropout echo" as indicated by repeated moderate dropout and recovery signatures of the flux of energetic electron in the out radiation belt region has been investigated systematically. The electron dropout and its echoes are usually found for higher energy (> 300 keV) channels fluxes, whereas the flux enhancements are obvious for lower energy electrons simultaneously after the interplanetary shock arrives at the Earth's geosynchronous orbit. 104 dropout echo events have been found from 215 interplanetary shock events from 1998 to 2007 based on LANL satellite data. In analogy to substorm injections, these 104 events could be naturally divided into two categories: dispersionless (49 events) or dispersive (55 events) according to the energy dispersion of the initial dropout. It is found that locations of dispersionless events are distributed mainly in the duskside magnetosphere. Further, the obtained locations derived from dispersive events with the time-of-flight technique of the initial dropout regions are mainly located at the duskside as well. Statistical studies have shown that the effect of shock normal, interplanetary magnetic field Bz and solar wind dynamic pressure may be insignificant to these electron dropout events. We suggest that the electric field impulse induced by the IP shock produces a more pronounced inward migration of electrons at the dusk side, resulting in the observed dusk-side moderate dropout of electron flux and its consequent echoes.

Optimization image of magnetic resonance imaging (MRI) T2 fast spin echo (FSE) with variation echo train length (ETL) on the rupture tendon achilles case

International Nuclear Information System (INIS)

Muzamil, Akhmad; Firmansyah, Achmad Haries

2017-01-01

The research was done the optimization image of Magnetic Resonance Imaging (MRI) T2 Fast Spin Echo (FSE) with variation Echo Train Length (ETL) on the Rupture Tendon Achilles case. This study aims to find the variations Echo Train Length (ETL) from the results of ankle’s MRI image and find out how the value of Echo Train Length (ETL) works on the MRI ankle to produce optimal image. In this research, the used ETL variations were 12 and 20 with the interval 2 on weighting T2 FSE sagittal. The study obtained the influence of Echo Train Length (ETL) on the quality of ankle MRI image sagittal using T2 FSE weighting and analyzed in 25 images of five patients. The data analysis has done quantitatively with the Region of Interest (ROI) directly on computer MRI image planes which conducted statistical tests Signal to Noise Ratio (SNR) and Contras to Noise Ratio (CNR). The Signal to Noise Ratio (SNR) was the highest finding on fat tissue, while the Contras to Noise Ratio (CNR) on the Tendon-Fat tissue with ETL 12 found in two patients. The statistics test showed the significant SNR value of the 0.007 (p<0.05) of Tendon tissue, 0.364 (p>0.05) of the Fat, 0.912 (p>0.05) of the Fibula, and 0.436 (p>0.05) of the Heel Bone. For the contrast to noise ratio (CNR) of the Tendon-FAT tissue was about 0.041 (p>0.05). The results of the study showed that ETL variation with T2 FSE sagittal weighting had difference at Tendon tissue and Tendon-Fat tissue for MRI imaging quality. SNR and CNR were an important aspect on imaging optimization process to give the diagnose information. (paper)

A short TE gradient-echo sequence using asymmetric sampling

International Nuclear Information System (INIS)

Fujita, Norihiko; Harada, Kohshi; Sakurai, Kosuke; Nakanishi, Katsuyuki; Kim, Shyogen; Kozuka, Takahiro

1990-01-01

We have developed a gradient-echo pulse sequence with a short TE less than 4 msec using a data set of asymmetric off-center sampling with a broad bandwidth. The use of such a short TE significantly reduces T 2 * dephasing effect even in a two-dimensional mode, and by collecting an off-center echo, motion-induced phase dispersion is also considerably decreased. High immunity of this sequence to these dephasing effects permits clear visualization of anatomical details near the skull base where large local field inhomogeneities and rapid blood flow such as in the internal carotid artery are present. (author)

Spin-echo Echo-planar Imaging MR Elastography versus Gradient-echo MR Elastography for Assessment of Liver Stiffness in Children and Young Adults Suspected of Having Liver Disease.

Science.gov (United States)

Serai, Suraj D; Dillman, Jonathan R; Trout, Andrew T

2017-03-01

Purpose To compare two-dimensional (2D) gradient-recalled echo (GRE) and 2D spin-echo (SE) echo-planar imaging (EPI) magnetic resonance (MR) elastography for measurement of hepatic stiffness in pediatric and young adult patients suspected of having liver disease. Materials and Methods In this institutional review board-approved, HIPAA-compliant study, 58 patients underwent both 2D GRE and 2D SE-EPI MR elastography at 1.5 T during separate breath holds. Liver stiffness (mean of means; in kilopascals) was measured by five blinded reviewers. Pooled mean liver stiffness and region-of-interest (ROI) size were compared by using paired t tests. Intraclass correlation coefficients (ICCs) were used to assess agreement between techniques. Respiratory motion artifacts were compared across sequences by using the Fisher exact test. Results Mean patient age was 14.7 years ± 5.2 (standard deviation; age range, 0.7-20.5 years), and 55.2% (32 of 58) of patients were male. Mean liver stiffness was 2.92 kPa ± 1.29 measured at GRE MR elastography and 2.76 kPa ± 1.39 at SE-EPI MR elastography (n = 290; P = .15). Mean ROI sizes were 8495 mm 2 ± 4482 for 2D GRE MR elastography and 15 176 mm 2 ± 7609 for 2D SE-EPI MR elastography (n = 290; P range, 0.91-0.95). Moderate or severe breathing artifacts were observed on 27.5% (16 of 58) of 2D GRE images versus 0% 2D SE-EPI images (P < .001). Conclusion There is excellent agreement on measured hepatic stiffness between 2D GRE and 2D SE-EPI MR elastography across multiple reviewers. SE-EPI MR elastography allowed for stiffness measurement across larger areas of the liver and can be performed in a single breath hold. © RSNA, 2016.

Geophysical investigations in Jordan

Science.gov (United States)

Kovach, R.L.; Andreasen, G.E.; Gettings, M.E.; El-Kaysi, K.

1990-01-01

A number of geophysical investigations have been undertaken in the Hashemite Kingdom of Jordan to provide data for understanding the tectonic framework, the pattern of seismicity, earthquake hazards and geothermal resources of the country. Both the historical seismic record and the observed recent seismicity point to the dominance of the Dead Sea Rift as the main locus of seismic activity but significant branching trends and gaps in the seismicity pattern are also seen. A wide variety of focal plane solutions are observed emphasizing the complex pattern of fault activity in the vicinity of the rift zone. Geophysical investigations directed towards the geothermal assessment of the prominent thermal springs of Zerga Ma'in and Zara are not supportive of the presence of a crustal magmatic source. ?? 1990.

Sound radiation contrast in MR phase images. Method for the representation of elasticity, sound damping, and sound impedance changes

International Nuclear Information System (INIS)

Radicke, Marcus

2009-01-01

The method presented in this thesis combines ultrasound techniques with the magnetic-resonance tomography (MRT). An ultrasonic wave generates in absorbing media a static force in sound-propagation direction. The force leads at sound intensities of some W/cm 2 and a sound frequency in the lower MHz range to a tissue shift in the micrometer range. This tissue shift depends on the sound power, the sound frequency, the sound absorption, and the elastic properties of the tissue. A MRT sequence of the Siemens Healthcare AG was modified so that it measures (indirectly) the tissue shift, codes as grey values, and presents as 2D picture. By means of the grey values the sound-beam slope in the tissue can be visualized, and so additionally sound obstacles (changes of the sound impedance) can be detected. By the MRT images token up spatial changes of the tissue parameters sound absorption and elasticity can be detected. In this thesis measurements are presented, which show the feasibility and future chances of this method especially for the mammary-cancer diagnostics. [de

Hazardous Waste Dashboard Help | ECHO | US EPA

Science.gov (United States)

The dashboards found on the Enforcement and Compliance History Online (ECHO) website are specialized to track both facility and agency performance as they relate to compliance with and enforcement of environmental standards under the Resource Conservation and Recovery Act (RCRA).

Geophysical fluid dynamics

CERN Document Server

Pedlosky, Joseph

1982-01-01

The content of this book is based, largely, on the core curriculum in geophys­ ical fluid dynamics which land my colleagues in the Department of Geophysical Sciences at The University of Chicago have taught for the past decade. Our purpose in developing a core curriculum was to provide to advanced undergraduates and entering graduate students a coherent and systematic introduction to the theory of geophysical fluid dynamics. The curriculum and the outline of this book were devised to form a sequence of courses of roughly one and a half academic years (five academic quarters) in length. The goal of the sequence is to help the student rapidly advance to the point where independent study and research are practical expectations. It quickly became apparent that several topics (e. g. , some aspects of potential theory) usually thought of as forming the foundations of a fluid-dynamics curriculum were merely classical rather than essential and could be, however sadly, dispensed with for our purposes. At the same tim...

Geophysical fluid dynamics

CERN Document Server

Pedlosky, Joseph

1979-01-01

The content of this book is based, largely, on the core curriculum in geophys­ ical fluid dynamics which I and my colleagues in the Department of Geophysical Sciences at The University of Chicago have taught for the past decade. Our purpose in developing a core curriculum was to provide to advanced undergraduates and entering graduate students a coherent and systematic introduction to the theory of geophysical fluid dynamics. The curriculum and the outline of this book were devised to form a sequence of courses of roughly one and a half academic years (five academic quarters) in length. The goal of the sequence is to help the student rapidly advance to the point where independent study and research are practical expectations. It quickly became apparent that several topics (e. g. , some aspects of potential theory) usually thought of as forming the foundations of a fluid-dynamics curriculum were merely classical rather than essential and could be, however sadly, dispensed with for our purposes. At the same ti...

Computer analysis of sound recordings from two Anasazi sites in northwestern New Mexico

Science.gov (United States)

Loose, Richard

2002-11-01

Sound recordings were made at a natural outdoor amphitheater in Chaco Canyon and in a reconstructed great kiva at Aztec Ruins. Recordings included computer-generated tones and swept sine waves, classical concert flute, Native American flute, conch shell trumpet, and prerecorded music. Recording equipment included analog tape deck, digital minidisk recorder, and direct digital recording to a laptop computer disk. Microphones and geophones were used as transducers. The natural amphitheater lies between the ruins of Pueblo Bonito and Chetro Ketl. It is a semicircular arc in a sandstone cliff measuring 500 ft. wide and 75 ft. high. The radius of the arc was verified with aerial photography, and an acoustic ray trace was generated using cad software. The arc is in an overhanging cliff face and brings distant sounds to a line focus. Along this line, there are unusual acoustic effects at conjugate foci. Time history analysis of recordings from both sites showed that a 60-dB reverb decay lasted from 1.8 to 2.0 s, nearly ideal for public performances of music. Echoes from the amphitheater were perceived to be upshifted in pitch, but this was not seen in FFT analysis. Geophones placed on the floor of the great kiva showed a resonance at 95 Hz.

CISS MR imaging findings of epidermoid tumor : comparison with spin-echo images

Energy Technology Data Exchange (ETDEWEB)

Kim, Yong Woo; Kim, Hak Jin; Choi, Sang Yoel; Heo, Jin Sam; Jung, Hoon Sik; Lee, Suck Hong; Kim, Byung Soo [Pusan National Univ. College of Medicine, Pusan (Korea, Republic of); Lee, Jong Wha [Ulsan Univ. Hospital, Ulsan (Korea, Republic of)

1999-03-01

To evaluate CISS MR imaging findings of epidermoid tumor in comparison with conventional spin-echo images. We studied 6 cases of epidermoid tumor in the subarachnoid space. We used a 1.5T MR unit to obtain CISS images(TR/TE/FA ; 12.3msec/5.9 msec/700) and T1- and T2- weighted spin-echo images. CISS MR imaging findings were evaluated with respect to tumor's signal intensity , contour, and relation with adjacent structures. Conspicuity of the tumor was compared between CISS and spin-echo images. A quantitative analysis was performed by measuring tumor to CSF contrast. In qualitative analysis, three radiologists independently compared CISS image and conventional spin-echo images for visibility of the tumor and graded them into three categories( poor, good, and excellent). Epidermoid tumors were located in the cerebellopontine angle in 4 cases, the prepontine cisstern in 1 case, and the cerebellopontine angle-prepontine cistern in 1 case. The tumors were hyperintense relative to brain parenchyma and hypointense relative to CSF on CISS images, were lobulated, encased adjacent cranial nerve and vessels, and invaginated into brain parenchyma. In qualitative analysis, CISS images showed clear demarcation between tumor and CSF, exact tumor extension, and tumor's relation with cranial nerves and vessels better than conventional spin-echo images. In quantitative analysis, the mean contrast values of tumor to CSF on T1-, T2-weighted images, and CISS images were 0.12, 0.06, and 0.52, respectively. The contrast value for CISS images was significantly higher than that for T1-and T2-weighted images(p<0.05). Epidermoid tumors in the subarachnoid space are better demonstrated on CISS images than on conventional spin-echo images. This special MR sequence can be added as a routine protocol in the diagnosis of subarachnoid epidermoid tumor.

Responsibilities, opportunities and challenges in geophysical exploration

International Nuclear Information System (INIS)

Rytle, R.J.

1982-01-01

Geophysical exploration for engineering purposes is conducted to decrease the risk in encountering site uncertainties in construction of underground facilities. Current responsibilities, opportunities and challenges for those with geophysical expertise are defined. These include: replacing the squiggly line format, developing verification sites for method evaluations, applying knowledge engineering and assuming responsibility for crucial national problems involving rock mechanics expertise

Global status of and prospects for protection of terrestrial geophysical diversity.

Science.gov (United States)

Sanderson, Eric W; Segan, Daniel B; Watson, James E M

2015-06-01

Conservation of representative facets of geophysical diversity may help conserve biological diversity as the climate changes. We conducted a global classification of terrestrial geophysical diversity and analyzed how land protection varies across geophysical diversity types. Geophysical diversity was classified in terms of soil type, elevation, and biogeographic realm and then compared to the global distribution of protected areas in 2012. We found that 300 (45%) of 672 broad geophysical diversity types currently meet the Convention on Biological Diversity's Aichi Target 11 of 17% terrestrial areal protection, which suggested that efforts to implement geophysical diversity conservation have a substantive basis on which to build. However, current protected areas were heavily biased toward high elevation and low fertility soils. We assessed 3 scenarios of protected area expansion and found that protection focused on threatened species, if fully implemented, would also protect an additional 29% of geophysical diversity types, ecoregional-focused protection would protect an additional 24%, and a combined scenario would protect an additional 42%. Future efforts need to specifically target low-elevation sites with productive soils for protection and manage for connectivity among geophysical diversity types. These efforts may be hampered by the sheer number of geophysical diversity facets that the world contains, which makes clear target setting and prioritization an important next step. © 2015 Society for Conservation Biology.

Brief overview of geophysical probing technology

International Nuclear Information System (INIS)

Ramirez, A.L.; Lytle, R.J.

1982-01-01

An evaluation of high-resolution geophysical techniques which can be used to characterize a nulcear waste disposal site is being conducted by the Lawrence Livermore National Laboratory (LLNL) at the request of the US Nuclear Regulatory Commisson (NRC). LLNL is involved in research work aimed at evaluating the current capabilities and limitations of geophysical methods used for site selection. This report provides a brief overview of the capabilities and limitations associated with this technology and explains how our work addresses some of the present limitations. We are examining both seismic and electromagnetic techniques to obtain high-resolution information. We are also assessing the usefulness of geotomography in mapping fracture zones remotely. Finally, we are collecting core samples from a site in an effort to assess the capability of correlating such geophysical data with parameters of interest such as fracture continuity, orientation, and fracture density

Geophysical Signitures From Hydrocarbon Contaminated Aquifers

Science.gov (United States)

Abbas, M.; Jardani, A.

2015-12-01

The task of delineating the contamination plumes as well as studying their impact on the soil and groundwater biogeochemical properties is needed to support the remediation efforts and plans. Geophysical methods including electrical resistivity tomography (ERT), induced polarization (IP), ground penetrating radar (GPR), and self-potential (SP) have been previously used to characterize contaminant plumes and investigate their impact on soil and groundwater properties (Atekwana et al., 2002, 2004; Benson et al., 1997; Campbell et al., 1996; Cassidy et al., 2001; Revil et al., 2003; Werkema et al., 2000). Our objective was to: estimate the hydrocarbon contamination extent in a contaminated site in northern France, and to adverse the effects of the oil spill on the groundwater properties. We aim to find a good combination of non-intrusive and low cost methods which we can use to follow the bio-remediation process, which is planned to proceed next year. We used four geophysical methods including electrical resistivity tomography, IP, GPR, and SP. The geophysical data was compared to geochemical ones obtained from 30 boreholes installed in the site during the geophysical surveys. Our results have shown: low electrical resistivity values; high chargeability values; negative SP anomalies; and attenuated GPR reflections coincident with groundwater contamination. Laboratory and field geochemical measurements have demonstrated increased groundwater electrical conductivity and increased microbial activity associated with hydrocarbon contamination of groundwater. Our study results support the conductive model suggested by studies such as Sauck (2000) and Atekwana et al., (2004), who suggest that biological alterations of hydrocarbon contamination can substantially modify the chemical and physical properties of the subsurface, producing a dramatic shift in the geo-electrical signature from resistive to conductive. The next stage of the research will include time lapse borehole

Geophysical monitoring in a hydrocarbon reservoir

Science.gov (United States)

Caffagni, Enrico; Bokelmann, Goetz

2016-04-01

Extraction of hydrocarbons from reservoirs demands ever-increasing technological effort, and there is need for geophysical monitoring to better understand phenomena occurring within the reservoir. Significant deformation processes happen when man-made stimulation is performed, in combination with effects deriving from the existing natural conditions such as stress regime in situ or pre-existing fracturing. Keeping track of such changes in the reservoir is important, on one hand for improving recovery of hydrocarbons, and on the other hand to assure a safe and proper mode of operation. Monitoring becomes particularly important when hydraulic-fracturing (HF) is used, especially in the form of the much-discussed "fracking". HF is a sophisticated technique that is widely applied in low-porosity geological formations to enhance the production of natural hydrocarbons. In principle, similar HF techniques have been applied in Europe for a long time in conventional reservoirs, and they will probably be intensified in the near future; this suggests an increasing demand in technological development, also for updating and adapting the existing monitoring techniques in applied geophysics. We review currently available geophysical techniques for reservoir monitoring, which appear in the different fields of analysis in reservoirs. First, the properties of the hydrocarbon reservoir are identified; here we consider geophysical monitoring exclusively. The second step is to define the quantities that can be monitored, associated to the properties. We then describe the geophysical monitoring techniques including the oldest ones, namely those in practical usage from 40-50 years ago, and the most recent developments in technology, within distinct groups, according to the application field of analysis in reservoir. This work is performed as part of the FracRisk consortium (www.fracrisk.eu); this project, funded by the Horizon2020 research programme, aims at helping minimize the

Wideband Radar Echo Frequency-domain Simulation and Analysis for High Speed Moving Targets

Directory of Open Access Journals (Sweden)

Ning Chao

2014-04-01

Full Text Available A frequency-domain method is proposed for wideband radar echo simulation of high-speed moving targets. Based on the physical process of electromagnetic waves observing a moving target, a frequency-domain echo model of wideband radar is constructed, and the block diagram of the radar echo simulation in frequency-domain is presented. Then, the impacts of radial velocity and slant range on the matching filtering of LFM radar are analyzed, and some quantitative conclusions on the shift and expansion of the radar profiles are obtained. Simulation results illustrate the correctness and efficiency of the proposed method.

Development of Prediction Tool for Sound Absorption and Sound Insulation for Sound Proof Properties

OpenAIRE

Yoshio Kurosawa; Takao Yamaguchi

2015-01-01

High frequency automotive interior noise above 500 Hz considerably affects automotive passenger comfort. To reduce this noise, sound insulation material is often laminated on body panels or interior trim panels. For a more effective noise reduction, the sound reduction properties of this laminated structure need to be estimated. We have developed a new calculate tool that can roughly calculate the sound absorption and insulation properties of laminate structure and handy ...

Parameterizing Sound: Design Considerations for an Environmental Sound Database

Science.gov (United States)

2015-04-01

associated with, or produced by, a physical event or human activity and 2) sound sources that are common in the environment. Reproductions or sound...Rogers S. Confrontation naming of environmental sounds. Journal of Clinical and Experimental Neuropsychology . 2000;22(6):830–864. 14 VanDerveer NJ

Modified echo peak correction for radial acquisition regime (RADAR).

Science.gov (United States)

Takizawa, Masahiro; Ito, Taeko; Itagaki, Hiroyuki; Takahashi, Tetsuhiko; Shimizu, Kanichirou; Harada, Junta

2009-01-01

Because radial sampling imposes many limitations on magnetic resonance (MR) imaging hardware, such as on the accuracy of the gradient magnetic field or the homogeneity of B(0), some correction of the echo signal is usually needed before image reconstruction. In our previous study, we developed an echo-peak-shift correction (EPSC) algorithm not easily affected by hardware performance. However, some artifacts remained in lung imaging, where tissue is almost absent, or in cardiac imaging, which is affected by blood flow. In this study, we modified the EPSC algorithm to improve the image quality of the radial aquisition regime (RADAR) and expand its application sequences. We assumed the artifacts were mainly caused by errors in the phase map for EPSC and used a phantom on a 1.5-tesla (T) MR scanner to investigate whether to modify the EPSC algorithm. To evaluate the effectiveness of EPSC, we compared results from T(1)- and T(2)-weighted images of a volunteer's lung region using the current and modified EPSC. We then applied the modified EPSC to RADAR spin echo (SE) and RADAR balanced steady-state acquisition with rewound gradient echo (BASG) sequence. The modified EPSC reduced phase discontinuity in the reference data used for EPSC and improved visualization of blood vessels in the lungs. Motion and blood flow caused no visible artifacts in the resulting images in either RADAR SE or RADAR BASG sequence. Use of the modified EPSC eliminated artifacts caused by signal loss in the reference data for EPSC. In addition, the modified EPSC was applied to RADAR SE and RADAR BASG sequences.

Modified echo peak correction for radial acquisition regime (RADAR)

International Nuclear Information System (INIS)

Takizawa, Masahiro; Ito, Taeko; Itagaki, Hiroyuki; Takahashi, Tetsuhiko; Shimizu, Kanichirou; Harada, Junta

2009-01-01

Because radial sampling imposes many limitations on magnetic resonance (MR) imaging hardware, such as on the accuracy of the gradient magnetic field or the homogeneity of B 0 , some correction of the echo signal is usually needed before image reconstruction. In our previous study, we developed an echo-peak-shift correction (EPSC) algorithm not easily affected by hardware performance. However, some artifacts remained in lung imaging, where tissue is almost absent, or in cardiac imaging, which is affected by blood flow. In this study, we modified the EPSC algorithm to improve the image quality of the radial acquisition regime (RADAR) and expand its application sequences. We assumed the artifacts were mainly caused by errors in the phase map for EPSC and used a phantom on a 1.5-tesla (T) MR scanner to investigate whether to modify the EPSC algorithm. To evaluate the effectiveness of EPSC, we compared results from T 1 -and T 2 -weighted images of a volunteer's lung region using the current and modified EPSC. We then applied the modified EPSC to RADAR spin echo (SE) and RADAR balanced steady-state acquisition with rewound gradient echo (BASG) sequence. The modified EPSC reduced phase discontinuity in the reference data used for EPSC and improved visualization of blood vessels in the lungs. Motion and blood flow caused no visible artifacts in the resulting images in either RADAR SE or RADAR BASG sequence. Use of the modified EPSC eliminated artifacts caused by signal loss in the reference data for EPSC. In addition, the modified EPSC was applied to RADAR SE and RADAR BASG sequences. (author)

Evaluation of the chondromalacia patella using a microscopy coil: comparison of the two-dimensional fast spin echo techniques and the three-dimensional fast field echo techniques.

Science.gov (United States)

Kim, Hyun-joo; Lee, Sang Hoon; Kang, Chang Ho; Ryu, Jeong Ah; Shin, Myung Jin; Cho, Kyung-Ja; Cho, Woo Shin

2011-01-01

We wanted to compare the two-dimensional (2D) fast spin echo (FSE) techniques and the three-dimensional (3D) fast field echo techniques for the evaluation of the chondromalacia patella using a microscopy coil. Twenty five patients who underwent total knee arthroplasty were included in this study. Preoperative MRI evaluation of the patella was performed using a microscopy coil (47 mm). The proton density-weighted fast spin echo images (PD), the fat-suppressed PD images (FS-PD), the intermediate weighted-fat suppressed fast spin echo images (iw-FS-FSE), the 3D balanced-fast field echo images (B-FFE), the 3D water selective cartilage scan (WATS-c) and the 3D water selective fluid scan (WATS-f) were obtained on a 1.5T MRI scanner. The patellar cartilage was evaluated in nine areas: the superior, middle and the inferior portions that were subdivided into the medial, central and lateral facets in a total of 215 areas. Employing the Noyes grading system, the MRI grade 0-I, II and III lesions were compared using the gross and microscopic findings. The sensitivity, specificity and accuracy were evaluated for each sequence. The significance of the differences for the individual sequences was calculated using the McNemar test. The gross and microscopic findings demonstrated 167 grade 0-I lesions, 40 grade II lesions and eight grade III lesions. Iw-FS-FSE had the highest accuracy (sensitivity/specificity/accuracy = 88%/98%/96%), followed by FS-PD (78%/98%/93%, respectively), PD (76%/98%/93%, respectively), B-FFE (71%/100%/93%, respectively), WATS-c (67%/100%/92%, respectively) and WATS-f (58%/99%/89%, respectively). There were statistically significant differences for the iw-FS-FSE and WATS-f and for the PD-FS and WATS-f (p chondromalacia patella.

Human listeners provide insights into echo features used by dolphins (Tursiops truncatus) to discriminate among objects.

Science.gov (United States)

Delong, Caroline M; Au, Whitlow W L; Harley, Heidi E; Roitblat, Herbert L; Pytka, Lisa

2007-08-01

Echolocating bottlenose dolphins (Tursiops truncatus) discriminate between objects on the basis of the echoes reflected by the objects. However, it is not clear which echo features are important for object discrimination. To gain insight into the salient features, the authors had a dolphin perform a match-to-sample task and then presented human listeners with echoes from the same objects used in the dolphin's task. In 2 experiments, human listeners performed as well or better than the dolphin at discriminating objects, and they reported the salient acoustic cues. The error patterns of the humans and the dolphin were compared to determine which acoustic features were likely to have been used by the dolphin. The results indicate that the dolphin did not appear to use overall echo amplitude, but that it attended to the pattern of changes in the echoes across different object orientations. Human listeners can quickly identify salient combinations of echo features that permit object discrimination, which can be used to generate hypotheses that can be tested using dolphins as subjects.

Optical decoherence times and spectral diffusion in an Er-doped optical fiber measured by two-pulse echoes, stimulated photon echoes, and spectral hole burning

International Nuclear Information System (INIS)

Macfarlane, R.M.; Sun, Y.; Sellin, P.B.; Cone, R.L.

2007-01-01

Two-pulse and stimulated photon echoes and spectral hole burning were measured on the transition from the lowest component of the 4 I 15/2 manifold to the lowest component of 4 I 13/2 of Er 3+ in a silicate optical fiber at 1.6 K. The two-pulse echo decays gave decoherence times as long as 230 ns for magnetic fields above 2 T. A large field dependent contribution to the homogeneous line width of >2 MHz was found and interpreted in terms of coupling to magnetic tunneling modes (TLS) in the glass. The stimulated echoes measured at 2 T showed spectral diffusion of 0.8 MHz/decade of time between 0.4 and 500 μs. Spectral diffusion in this high field region is attributed to coupling to elastic TLS modes which have a distribution of flip rates in glasses. Time-resolved spectral hole burning at very low field showed stronger spectral diffusion of 5.7 MHz/decade of time, attributed to coupling to magnetic spin-elastic TLS modes

Making fictions sound real - On film sound, perceptual realism and genre

Directory of Open Access Journals (Sweden)

Birger Langkjær

2010-05-01

Full Text Available This article examines the role that sound plays in making fictions perceptually real to film audiences, whether these fictions are realist or non-realist in content and narrative form. I will argue that some aspects of film sound practices and the kind of experiences they trigger are related to basic rules of human perception, whereas others are more properly explained in relation to how aesthetic devices, including sound, are used to characterise the fiction and thereby make it perceptually real to its audience. Finally, I will argue that not all genres can be defined by a simple taxonomy of sounds. Apart from an account of the kinds of sounds that typically appear in a specific genre, a genre analysis of sound may also benefit from a functionalist approach that focuses on how sounds can make both realist and non-realist aspects of genres sound real to audiences.

Making fictions sound real - On film sound, perceptual realism and genre

Directory of Open Access Journals (Sweden)

Birger Langkjær

2009-09-01

Full Text Available This article examines the role that sound plays in making fictions perceptually real to film audiences, whether these fictions are realist or non-realist in content and narrative form. I will argue that some aspects of film sound practices and the kind of experiences they trigger are related to basic rules of human perception, whereas others are more properly explained in relation to how aesthetic devices, including sound, are used to characterise the fiction and thereby make it perceptually real to its audience. Finally, I will argue that not all genres can be defined by a simple taxonomy of sounds. Apart from an account of the kinds of sounds that typically appear in a specific genre, a genre analysis of sound may also benefit from a functionalist approach that focuses on how sounds can make both realist and non-realist aspects of genres sound real to audiences.

Modeling geophysical complexity: a case for geometric determinism

Directory of Open Access Journals (Sweden)

C. E. Puente

2007-01-01

Full Text Available It has been customary in the last few decades to employ stochastic models to represent complex data sets encountered in geophysics, particularly in hydrology. This article reviews a deterministic geometric procedure to data modeling, one that represents whole data sets as derived distributions of simple multifractal measures via fractal functions. It is shown how such a procedure may lead to faithful holistic representations of existing geophysical data sets that, while complementing existing representations via stochastic methods, may also provide a compact language for geophysical complexity. The implications of these ideas, both scientific and philosophical, are stressed.

MPD model for radar echo signal of hypersonic targets

Directory of Open Access Journals (Sweden)

Xu Xuefei

2014-08-01

Full Text Available The stop-and-go (SAG model is typically used for echo signal received by the radar using linear frequency modulation pulse compression. In this study, the authors demonstrate that this model is not applicable to hypersonic targets. Instead of SAG model, they present a more realistic echo signal model (moving-in-pulse duration (MPD for hypersonic targets. Following that, they evaluate the performances of pulse compression under the SAG and MPD models by theoretical analysis and simulations. They found that the pulse compression gain has an increase of 3 dB by using the MPD model compared with the SAG model in typical cases.

Geophysics comes of age in oil sands development

Energy Technology Data Exchange (ETDEWEB)

Bauman, P. [WorleyParsons Komex, Calgary, AB (Canada); Birch, R.; Parker, D.; Andrews, B. [Calgary Univ., AB (Canada). Dept. of Geology and Geophysics

2008-07-01

This paper discussed geophysical techniques developed for oil sands exploration and production applications in Alberta's oil sands region. Geophysical methods are playing an important role in mine planning, tailings containment, water supply, and land reclamation activities. Geophysics techniques are used to estimate the volume of muskeg that needs to be stripped and stored for future reclamation activities as well as to site muskeg piles and delineate the thickness of clay Clearwater formations overlying Cretaceous oil-bearing sands. 2-D electrical resistivity mapping is used to map river-connected deep bedrock Pleistocene paleovalleys in the region. Geophysical studies are also used to investigate the interiors of dikes and berms as well as to monitor salt migration within tailings piles. Sonic and density logs are used to create synthetic seismograms for mapping the Devonian surface in the region. The new applications included the calculation of bitumen saturation from surface sands and shales; muskeg thickness mapping; and non-intrusive monitoring of leachate plumes. Geophysical techniques included 2-D electrical resistivity imaging; transient electromagnetic (EM) technologies; ground penetrating radar; and high-resolution seismic reflections. Polarization, surface nuclear magnetic resonance and push-probe sensing techniques were also discussed. Techniques were discussed in relation to Alberta's Athabasca oil sands deposits. 4 refs.

The application actualities and prospects of geophysical methods to uranium prospecting

International Nuclear Information System (INIS)

Liu Qingcheng

2010-01-01

Basic principles of geophysical methods to uranium prospect are briefly introduced, and the effects as well as problems in using those methods are analysed respectively. Combining with the increasing demand of uranium resources for Chinese nuclear power development and the higher requirements of geophysical techniques, the developing directions and the thoughts of geophysical techniques in uranium prospecting were proposed. A new pattern with producing, teaching and researching together is brought forward to develop advancing uranium prospecting key technologies and to break through technological bottlenecks depending on independent innovation. Integrated geophysical methods for prospecting uranium deposits are suggested. The method includes geophysical techniques as follows: gravity, magnetic, seismic, radioactive, remote sensing, and geochemical method in some proving grounds. Based on the experimental research, new uranium deposits prospecting models with efficient integrated geophysical methods can be established. (authors)

Gravitational wave echoes from macroscopic quantum gravity effects

Energy Technology Data Exchange (ETDEWEB)

Barceló, Carlos [Instituto de Astrofísica de Andalucía (IAA-CSIC),Glorieta de la Astronomía, 18008 Granada (Spain); Carballo-Rubio, Raúl [The Cosmology & Gravity Group and the Laboratory for Quantum Gravity & Strings,Department of Mathematics & Applied Mathematics, University of Cape Town,Private Bag, Rondebosch 7701 (South Africa); Garay, Luis J. [Departamento de Física Teórica II,Universidad Complutense de Madrid, 28040 Madrid (Spain); Instituto de Estructura de la Materia (IEM-CSIC),Serrano 121, 28006 Madrid (Spain)

2017-05-10

New theoretical approaches developed in the last years predict that macroscopic quantum gravity effects in black holes should lead to modifications of the gravitational wave signals expected in the framework of classical general relativity, with these modifications being characterized in certain scenarios by the existence of dampened repetitions of the primary signal. Here we use the fact that non-perturbative corrections to the near-horizon external geometry of black holes are necessary for these modifications to exist, in order to classify different proposals and paradigms with respect to this criterion and study in a neat and systematic way their phenomenology. Proposals that lead naturally to the existence of echoes in the late-time ringdown of gravitational wave signals from black hole mergers must share the replacement of black holes by horizonless configurations with a physical surface showing reflective properties in the relevant range of frequencies. On the other hand, proposals or paradigms that restrict quantum gravity effects on the external geometry to be perturbative, such as black hole complementarity or the closely related firewall proposal, do not display echoes. For the sake of completeness we exploit the interplay between the timescales associated with the formation of firewalls and the mechanism behind the existence of echoes in order to conclude that even unconventional distortions of the firewall concept (such as naked firewalls) do not lead to this phenomenon.

Proton T2 relaxation effect of superparamagnetic iron oxide. Comparison between fast spin echo and conventional spin echo sequence

International Nuclear Information System (INIS)

Tanimoto, Akihiro; Satoh, Yoshinori; Higuchi, Nobuya; Izutsu, Mutsumu; Yuasa, Yuji; Hiramatsu, Kyoichi

1995-01-01

Superparamagnetic iron oxide (SPIO) particles have been known to show a great T 2 relaxation effect in the liver, which contributes to significant liver signal decrease and detection of hepatic neoplasms. Recently, fast spin echo (FSE) sequence with less scanning time than conventional spin echo (SE) sequence has been rapidly introduced in clinical MR imaging. To investigate whether SPIO would show decreased T 2 relaxation effect on FSE, we obtained T 2 relaxivity (R2) of SPIO in vitro and liver signal decrease caused by SPIO in vivo. SPIO showed 20% less R2 on Carr-Purcell-Meiboom-Gill (CPMG) sequence than on SE. Relative liver signal-to-noise ratio (SNR) decrease caused by SPIO was significantly smaller (p 2 relaxation effect on FSE than on SE. However, further studies will be required to assess the diagnostic capability of SPIO on FSE, in the detection of hepatic neoplasms. (author)

The use of Impact-Echo and Spectral-Analysis-of-Surface-Waves methods for the concrete investigation of Rogers Dam spillway structure

International Nuclear Information System (INIS)

Olson, L.D.; Sack, D.A.; Chan, Y.F.; Gilmore, R.T.; Christy, J.T.; Dumont, M.F.

1994-01-01

IE and SASW NDT methods were employed to investigate the concrete conditions of the Rogers Hydro Station's concrete spillway. The results showed that the surface gunite/shotcrete on the majority of the piers and walls was delaminated from the interior sound concrete and that there was a significant amount of sound concrete in the interior cores of the piers and walls. The NDT results correspond well in general trend with those of the concrete coring performed in 1988 and 1991; however, because of the greatly varying concrete conditions and additional concrete deterioration since 1988 when the majority of the horizontal cores were taken, a direct point-per-point comparison cannot be made. The NDT results correspond well with the as-found conditions on Pier 1 and on the east abutment wall except that the deep degradation (SASW results) conditions on the west face of Pier 1 did not exist. The highly deteriorated nature of the concrete could have contributed to the lower wave velocities. The cracking conditions below the demolition line were not verified. Some of the IE echoes could have been caused by the boundary conditions, in view of the highly fractured nature of the surface concrete/shotcrete and the very low strength and deteriorated concrete at the construction joints

Slow flow and mural thrombus in aortic diseases: Spin-echo MR findings and their differentiation

International Nuclear Information System (INIS)

Chung, Jin Wook; Park, Jae Hyung; Han, Man Chung

1993-01-01

In order to evaluate the ability of spin-echo MR imaging to differentiate slow flow from mural thrombus in aortic diseases, we reviewed the spin-echo MR images of 13 patients with intraaortic thrombus documented by CT (N=11) or aortography (N=2). Six patients had aortic aneurysms and seven had aortic dissections. Intraaortic mural thrombi were accompanied by flow-related intraluminal signal of various pattern and extents in all 13 patients. On 10 gated MR studies, slow flow regions showed ever-echo rephasing phenomenon (N=8), interslice variation of signal intensities of the intraluminal signal (N=7) and flow-related ghost artifact (N=2). However, these MR flow phenomena were obscured on two of three non-gated studies. Seven of 13 intraaortic thrombi remained hyperintense on T2-weighted second-echo images. In these circumstance, a hypointense boundary layer between slow flow and mural thrombus, which was caused by either ' boundary layer dephasing phenomenon' of slow flow or 'paramagnetic T2 shortening' of fresh clot at the edge of mural thrombus, was very useful in discriminating the area of slow flow from that of mural thrombus. Proper interpretation of spin-echo MR images may obviate the need for phase display imaging or gradient-echo imaging in differentiating slow flow and mural thrombus

Supporting and improving community health services-a prospective evaluation of ECHO technology in community palliative care nursing teams.

Science.gov (United States)

White, Clare; McIlfatrick, Sonja; Dunwoody, Lynn; Watson, Max

2015-12-01

Project ECHO (Extension for Community Healthcare Outcomes) uses teleconferencing technology to support and train healthcare providers (HCPs) remotely, and has improved care across the USA. A 6-month pilot was trialled in a community palliative care nursing setting to determine if ECHO would be effective in the UK in providing education and support to community hospice nurses (CHN). The pilot involved weekly 2 hour sessions of teaching and case-based discussions facilitated by hospice staff linking with nine teams of CHN using video conferencing technology. A mixed-methods prospective longitudinal cohort study was used to evaluate the pilot. Each CHN provided demographic data, and completed a written knowledge assessment and a self-efficacy tool before and after the pilot. Two focus groups were also performed after the pilot. 28 CHNs completed the evaluation. Mean knowledge score improved significantly from 71.3% to 82.7% (p=0.0005) as did overall self-efficacy scores following the ECHO pilot. Pre-ECHO (p=0.036) and Retro-Pretest ECHO (p=0.0005) self-efficacy were significantly lower than post-ECHO. There was no significant difference between Pretest and Retro-Pretest ECHO self-efficacy (p=0.063). 96% recorded gains in learning, and 90% felt that ECHO had improved the care they provided for patients. 83% would recommend ECHO to other HCPs. 70% stated the technology used in ECHO had given them access to education that would have been hard to access due to geography. This study supports the use of Project ECHO for CHNs in the UK by demonstrating how a 6-month pilot improved knowledge and self-efficacy. As a low-cost high-impact model, ECHO provides an affordable solution to addressing growing need. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Basic elements of nuclear geophysics

International Nuclear Information System (INIS)

Nordemann, D.J.R.; Pereira, E.B.

1984-01-01

Nuclear Geophysics applies the nuclear radiation detection methodology to the geosciences, specially to study the dynamical processes of the lithosphere, the hydrosphere and the atmosphere as well as some aspects of planetology and astrophysics. Here the main methods are described: alpha-ray and gamma-ray spectrometry, the interaction of alpha and gamma radiation with matter and the detectors used (grid chambers, surface barrier silicon detector for alpha radiation; and sodium iodide thallium activated phosphors, hyperpure and lithium drifted germanium semiconductor detectors for gamma radiation). The principal applications of Nuclear Geophysics are given as examples to ilustrate the use of the methods described. (AUthor) [pt

Rotation commensurate echo of asymmetric molecules—Molecular fingerprints in the time domain

Energy Technology Data Exchange (ETDEWEB)

Chesnokov, E. N., E-mail: chesnok@kinetics.nsc.ru [Institute of Chemical Kinetics and Combustion, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Kubarev, V. V. [Budker Institute of Nuclear Physics, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Koshlyakov, P. V. [Institute of Chemical Kinetics and Combustion, Novosibirsk 630090 (Russian Federation)

2014-12-29

Using the pulses of terahertz free electron laser and ultra-fast Schottky diode detectors, we observed the coherent transients within a free induction decay of gaseous nitrogen dioxide NO{sub 2}. The laser excited different sub-bands of rotation spectra of NO{sub 2} containing about 50–70 lines. The free induction signal continued more than 30 ns and consisted of many echo-like bursts duration about 0.2 ns. Unlike the similar effect observed previously for linear and symmetric top molecules, the sequence of echo bursts is not periodic. The values for delay of individual echo are stable, and the set of these delays can be considered as a “molecular fingerprint” in the time domain.

The geology and geophysics of the Oslo rift

Science.gov (United States)

Ruder, M. E.

1981-01-01

The regional geology and geophysical characteristics of the Oslo graben are reviewed. The graben is part of a Permian age failed continental rift. Alkali olivine, tholefitic, and monzonitic intrusives as well as basaltic lavas outline the extent of the graben. Geophysical evidence indicates that rifting activity covered a much greater area in Skagerrak Sea as well as the Paleozoic time, possibly including the northern Skagerrak Sea as well as the Oslo graben itself. Much of the surficial geologic characteristics in the southern part of the rift have since been eroded or covered by sedimentation. Geophysical data reveal a gravity maximum along the strike of the Oslo graben, local emplacements of magnetic material throughout the Skagerrak and the graben, and a slight mantle upward beneath the rift zone. Petrologic and geophysical maps which depict regional structure are included in the text. An extensive bibliography of pertinent literature published in English between 1960 and 1980 is also provided.

Geophysical characterisation of the groundwater-surface water interface

Science.gov (United States)

McLachlan, P. J.; Chambers, J. E.; Uhlemann, S. S.; Binley, A.

2017-11-01

Interactions between groundwater (GW) and surface water (SW) have important implications for water quantity, water quality, and ecological health. The subsurface region proximal to SW bodies, the GW-SW interface, is crucial as it actively regulates the transfer of nutrients, contaminants, and water between GW systems and SW environments. However, geological, hydrological, and biogeochemical heterogeneity in the GW-SW interface makes it difficult to characterise with direct observations. Over the past two decades geophysics has been increasingly used to characterise spatial and temporal variability throughout the GW-SW interface. Geophysics is a powerful tool in evaluating structural heterogeneity, revealing zones of GW discharge, and monitoring hydrological processes. Geophysics should be used alongside traditional hydrological and biogeochemical methods to provide additional information about the subsurface. Further integration of commonly used geophysical techniques, and adoption of emerging techniques, has the potential to improve understanding of the properties and processes of the GW-SW interface, and ultimately the implications for water quality and environmental health.

Site characterization and validation - geophysical single hole logging

International Nuclear Information System (INIS)

Andersson, Per

1989-05-01

A total of 15 boreholes have been drilled for preliminary characterization of a previously unexplored site at the 360 and 385 m level in the Stripa mine. To adequately described the rock mass in the vicinity of these boreholes, a comprehensive program utilizing a large number of geophysical borehole methods has been carried out in 10 of these boreholes. The specific geophysical character of the rock mass and the major deformed units distinguished in the vicinity of the boreholes are recognized, and in certain cases also correlated between the boreholes. A general conclusion based on the geophysical logging results, made in this report, is that the preliminary predictions made in stage 2, of the site characterization and validation project (Olsson et.al, 1988), are adequate. The results from the geophysical logging can support the four predicted fracture/ fracture zones GHa, GHb, GA and GB whereas the predicted zones GC and GI are hard to confirm from the logging results. (author)

ASYMMETRY IN THE OUTBURST OF SN 1987A DETECTED USING LIGHT ECHO SPECTROSCOPY

International Nuclear Information System (INIS)

Sinnott, B.; Welch, D. L.; Sutherland, P. G.; Rest, A.; Bergmann, M.

2013-01-01

We report direct evidence for asymmetry in the early phases of SN 1987A via optical spectroscopy of five fields of its light echo system. The light echoes allow the first few hundred days of the explosion to be reobserved, with different position angles providing different viewing angles to the supernova. Light echo spectroscopy therefore allows a direct spectroscopic comparison of light originating from different regions of the photosphere during the early phases of SN 1987A. Gemini multi-object spectroscopy of the light echo fields shows fine structure in the Hα line as a smooth function of position angle on the near-circular light echo rings. Hα profiles originating from the northern hemisphere of SN 1987A show an excess in redshifted emission and a blue knee, while southern hemisphere profiles show an excess of blueshifted Hα emission and a red knee. This fine structure is reminiscent of the 'Bochum event' originally observed for SN 1987A, but in an exaggerated form. Maximum deviation from symmetry in the Hα line is observed at position angles 16° and 186°, consistent with the major axis of the expanding elongated ejecta. The asymmetry signature observed in the Hα line smoothly diminishes as a function of viewing angle away from the poles of the elongated ejecta. We propose an asymmetric two-sided distribution of 56 Ni most dominant in the southern far quadrant of SN 1987A as the most probable explanation of the observed light echo spectra. This is evidence that the asymmetry of high-velocity 56 Ni in the first few hundred days after explosion is correlated to the geometry of the ejecta some 25 years later.

Sound Absorbers

Science.gov (United States)

Fuchs, H. V.; Möser, M.

Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

Hydrostratigraphic interpretation of test-hole and surface geophysical data, Elkhorn and Loup River Basins, Nebraska, 2008 to 2011

Science.gov (United States)

Hobza, Christopher M.; Bedrosian, Paul A.; Bloss, Benjamin R.

2012-01-01

The Elkhorn-Loup Model (ELM) was begun in 2006 to understand the effect of various groundwater-management scenarios on surface-water resources. During phase one of the ELM study, a lack of subsurface geological information was identified as a data gap. Test holes drilled to the base of the aquifer in the ELM study area are spaced as much as 25 miles apart, especially in areas of the western Sand Hills. Given the variable character of the hydrostratigraphic units that compose the High Plains aquifer system, substantial variation in aquifer thickness and characteristics can exist between test holes. To improve the hydrogeologic understanding of the ELM study area, the U.S. Geological Survey, in cooperation with the Nebraska Department of Natural Resources, multiple Natural Resources Districts participating in the ELM study, and the University of Nebraska-Lincoln Conservation and Survey Division, described the subsurface lithology at six test holes drilled in 2010 and concurrently collected borehole geophysical data to identify the base of the High Plains aquifer system. A total of 124 time-domain electromagnetic (TDEM) soundings of resistivity were collected at and between selected test-hole locations during 2008-11 as a quick, non-invasive means of identifying the base of the High Plains aquifer system. Test-hole drilling and geophysical logging indicated the base-of-aquifer elevation was less variable in the central ELM area than in previously reported results from the western part of the ELM study area, where deeper paleochannels were eroded into the Brule Formation. In total, more than 435 test holes were examined and compared with the modeled-TDEM soundings. Even where present, individual stratigraphic units could not always be identified in modeled-TDEM sounding results if sufficient resistivity contrast was not evident; however, in general, the base of aquifer [top of the aquifer confining unit (ACU)] is one of the best-resolved results from the TDEM

31P NMR imaging of solid bone with solid echoes combined with refocused gradients

International Nuclear Information System (INIS)

Li, L.; Utah Univ., Salt Lake City, UT; Kruger, R.A.

1990-01-01

This note on 31 p NMR imaging presents some observations of the solid echoes acquired from solid bone and how the proposed solid echo imaging method can be employed to obtain the 31 images of solid bone. (UK)

Geophysical investigations in the Syyry area, Finland

International Nuclear Information System (INIS)

Heikkinen, E.; Kurimo, M.

1992-12-01

Investigations were carried out at the Syyry site at Sievi using geological, geophysical, geohydrological and geochemical methods in 1987-1991 to determine the suitability of the bedrock for the final disposal of spent nuclear fuel. In this survey airborne, ground and borehole geophysical methods were used to study the rock type distribution, fracturing and hydraulic conductivity of the bedrock to a depth of one kilometre

Geophysical investigations in the Olkiluoto area, Finland

International Nuclear Information System (INIS)

Heikkinen, E.; Paananen, M.

1992-12-01

Investigations were carried out at the Olkiluoto site at Eurajoki using geological, geophysical, geohydrological and geochemical methods in 1987-1992 to determine the suitability of the bedrock for the final disposal of spent nuclear fuel. In this survey airborne, ground and borehole geophysical methods were used to study the rock type distribution, fracturing and hydraulic conductivity of the bedrock to a depth of one kilometre

Geophysical investigations in the Kivetty area, Finland

International Nuclear Information System (INIS)

Heikkinen, E.; Paananen, M.; Oehberg, A.; Front, K.; Okko, O.; Pitkaenen, P.

1992-09-01

Investigations were carried out at Kivetty site in Konginkangas, in central Finland, by geological, geophysical, geohydrological and geochemical methods in 1987-1991 to determine the suitability of the bedrock for the final disposal of spent nuclear fuel. Airborne, ground and borehole geophysical methods were used to study the rock type distribution, fracturing and hydraulic conductivity of the bedrock to a depth of one kilometre

Electrical Resistivity Structure of the Valles Caldera, New Mexico, USA: Results From 3D Inversion of Modern and Legacy Magnetotelluric Data Collected by Industry and the Summer of Applied Geophysical Experience (SAGE).

Science.gov (United States)

Feucht, D. W.; Bedrosian, P.; Jiracek, G. R.; Pellerin, L.; Nettleton, C. E.

2017-12-01

The Valles caldera, in north-central New Mexico, USA, is a 20-km wide topographic depression in the Jemez Mountains volcanic complex that formed during two massive ignimbrite eruptions 1.65 and 1.26 Ma. Post-collapse volcanic activity in the caldera includes the rise of a 1 km high resurgent dome, periodic eruptions of the Valles rhyolite along ring fractures, and the presence of a geothermal reservoir beneath the western caldera with temperatures in excess of 300°C at a mere 2 km depth. We present an electrical resistivity model of the upper crust from three-dimensional (3D) inversion of broadband (100 Hz to 600 s) magnetotelluric (MT) data collected in and around the Valles caldera. The Summer of Applied Geophysical Experience (SAGE) has been acquiring geophysical data in the northern Rio Grande rift for more than three decades (1983-2017). Included in that vast dataset are over 60 broadband magnetotelluric soundings that have recently been cataloged, geo-located, and digitized for use in modern geophysical processing and modeling. The resistivity models presented here were produced by inverting a subset of SAGE MT data along with 30 broadband MT soundings acquired by the Unocal Corporation in 1983 for geothermal exploration of the caldera. We use the 3D inversion algorithm ModEM (Egbert and Kelbert, 2012) to invert full impedance tensors and tipper functions from >30 MT stations for the electrical resistivity structure beneath the caldera. Our preferred model reveals the geometry and electrical properties of (1) the conductive caldera fill, (2) the resistive crystalline basement, and (3) an enigmatic mid-crustal conductor related to magmatic activity that post-dates caldera formation.

Output Pressure and Pulse-Echo Characteristics of CMUTs as Function of Plate Dimensions

DEFF Research Database (Denmark)

Diederichsen, Søren Elmin; Hansen, Jesper Mark Fly; Engholm, Mathias

2017-01-01

This paper presents an experimental study of the acoustic performance of Capacitive Micromachined Ultrasonic Transducers (CMUTs) as function of plate dimensions. The objective is to increase the output pressure without decreasingthe pulse-echo signal. The CMUTs are fabricated with a LOCOS process......-to-peak output pressure and pulse-echo signal is obtained for the 9.3μm plate, which still has a moderate pulseecho bandwidth of 60%. The 9.3μm plate results in a 1.9 times higher peak-to-peak output pressure and a 3.6 times higherpulse-echo signal compared to the 2μm plate. By adjusting the plate dimensions...

Depolarization of neutron spin echo by magnetic fluid

International Nuclear Information System (INIS)

Achiwa, N.; Sirozu, G.; Nishioka, T.; Ebisawa, T.; Hino, M.; Tasaki, S.; Kawai, T.; Yamazaki, D.

2001-01-01

A new method to study the fluctuations of magnetization in magnetic fluids by measuring relations between the phase shift of Larmor precession and the visibility of the neutron spin echo caused by the change of flight path length is studied. Magnetic fluid in which fine particles of magnetite of about 10 nm diameters coated with oleic acid and suspended in water was used. Thickness of the sample was 2 mm. In the dynamics of magnetic fluids, Brownian motions of colloids and the thermal fluctuations of magnetization known as the superparamagnetism are dominant. Isolated ferromagnetic particles of the present size are superparamagnetic but they aggregate to form clusters in a weak magnetic field in the sample of 40% weight density. When neutrons pass the sample, spins process in the magnetic flux density of the clusters fluctuating in time and space. Consequently the Larmor precession phases become distributed and the quantization axes are fluctuated. The result is observed as a decrease of the visibility of the spin echo signals. The change of magnetic flux density in the magnetic fluid is measured from the change of echo visibility of the neutrons, vice versa. In the present experiment, echo was measured at q=0. It is observed that the phase shift changes as a quadratic function of the sample angle reflecting the change of the path length through the sample. Since the number of Larmor precession is proportional to the product of the magnetic field and the length of the flight path, mean flux density in the magnetic fluid is calculated from the phase shift. On the other hand, the decrease of the spin echo amplitude as the function of the sample angle reflects the time and space fluctuations of the flux density in the sample. If the direction of the magnetic flux density vector (quantization axis) changes slowly enough compared to the Larmor precession period while a neutron passes one magnetic domain, the neutron spin rotation in the domain is given by the spin

Efficient Multichannel NLMS Implementation for Acoustic Echo Cancellation

Directory of Open Access Journals (Sweden)

Schüldt Christian

2007-01-01

Full Text Available An acoustic echo cancellation structure with a single loudspeaker and multiple microphones is, from a system identification perspective, generally modelled as a single-input multiple-output system. Such a system thus implies specific echo-path models (adaptive filter for every loudspeaker to microphone path. Due to the often large dimensionality of the filters, which is required to model rooms with standard reverberation time, the adaptation process can be computationally demanding. This paper presents a selective updating normalized least mean square (NLMS-based method which reduces complexity to nearly half in practical situations, while showing superior convergence speed performance as compared to conventional complexity reduction schemes. Moreover, the method concentrates the filter adaptation to the filter which is most misadjusted, which is a typically desired feature.

Efficient Multichannel NLMS Implementation for Acoustic Echo Cancellation

Directory of Open Access Journals (Sweden)

Fredric Lindstrom

2007-02-01

Full Text Available An acoustic echo cancellation structure with a single loudspeaker and multiple microphones is, from a system identification perspective, generally modelled as a single-input multiple-output system. Such a system thus implies specific echo-path models (adaptive filter for every loudspeaker to microphone path. Due to the often large dimensionality of the filters, which is required to model rooms with standard reverberation time, the adaptation process can be computationally demanding. This paper presents a selective updating normalized least mean square (NLMS-based method which reduces complexity to nearly half in practical situations, while showing superior convergence speed performance as compared to conventional complexity reduction schemes. Moreover, the method concentrates the filter adaptation to the filter which is most misadjusted, which is a typically desired feature.

Geophysical Research in the Ganuelas-Mazarron Tertiary Basin (Murcia, Spain), as a Natural Analogue of CO2 Storage and Leakage

International Nuclear Information System (INIS)

Rodrigo-Naharro, J.; Aracil, E.; Perez del Villar, L.

2013-01-01

In order to determine the depth, morphology and extent of the CO 2 -enriched deep saline aquifer in the Ganuelas-Mazarron Tertiary basin (Murcia, Spain), it was necessary reprocessing the vertical electrical soundings performed by IGME-ADARO in the eighties and to perform several geophysical campaigns by means of electrical tomography, time domain electromagnetic surveys and gravimetry. Densities of the outcropping lithologies in the studied basin were also determined in order to refine the model obtained from gravimetric data. The geophysical results, particularly from gravimetric data, seem to indicate that the CO 2 -enriched deep saline aquifer, located in the contact or within the carbonate materials of the Nevado-Filabride Complex, could reach a depth greater than 800 m. For this reason, the possibility that this CO 2 is in supercritical state in certain areas of the aquifer, is not discardable. Thus, the studied basin would be an excellent natural analogue of a CO 2 -deep geological storage in a deep saline aquifer in volcanic and/or carbonate rocks, anthropogenically perturbed by geothermal exploration wells (La Ermita de El Saladillo and El Alto de El Reventon) and hydrogeological wells for agricultural purposes. (Author)

Making Sound Connections

Science.gov (United States)

Deal, Walter F., III

2007-01-01

Sound provides and offers amazing insights into the world. Sound waves may be defined as mechanical energy that moves through air or other medium as a longitudinal wave and consists of pressure fluctuations. Humans and animals alike use sound as a means of communication and a tool for survival. Mammals, such as bats, use ultrasonic sound waves to…

Development of radio acoustic sounding system (RASS with Gadanki MST radar – first results

Directory of Open Access Journals (Sweden)

T. Tsuda

2008-09-01

Full Text Available A high-power acoustic exciter was designed and developed for the Gadanki MST Radar to facilitate observations in the Radio Acoustic Sounding System (RASS mode. Sweep range of acoustic signal frequencies was set to 94–125 Hz so as to satisfy Bragg matching condition for temperature range of −90°–40°C between surface and the tropopause (about 17 km. Raytracing of acoustic wave propagation was used to predict the antenna beam directions along which optimum RASS echoes could be obtained. During the RASS observation period of about 18 h on 23–24 July 2006 height profiles of atmospheric virtual temperature were obtained between 1.5 km and 10 km and occasionally up to 14 km. In comparison with the three simultaneous radiosonde launches, RASS derived temperature profiles had the r.m.s. discrepancy of about 1 K, although deviation of the RASS results sometimes appeared when the radial wind velocity was not fully available for the correction of apparent sound speed. This study has successfully demonstrated capability of the RASS application with the Gadanki MST radar, which will be used for continuous monitoring of the temperature profiles in the troposphere and lower stratosphere region in the tropics.

Moving Beyond IGY: An Electronic Geophysical Year (eGY) Concept

Science.gov (United States)

Baker, D. N.; Barton, C. E.; Rodger, A. S.; Thompson, B. J.; Fraser, B.; Papitashvili, V.

2003-12-01

During the International Geophysical Year (1957-1958), member countries established many new geophysical observatories pursuing the major IGY objectives - to collect geophysical data as widely as possible and to provide free access to these data for all scientists around the globe. Today, geophysics has attained a rather good understanding within traditional regions, i.e., the atmosphere, ionosphere, magnetosphere, and other such geospheres. At the same time, it has become clear that much of the new and important science is coming from the studies of interfaces and coupling between geospheres. Thus, if geophysical data are made `'transparently'' available to a much wider range of scientists and students than to those who do the observations, then new and exciting discoveries can be expected. An International Association of Geomagnetic and Aeronomy (IAGA) task force, recognizing that a key achievement of the IGY was the establishment of a worldwide system of data centers and physical observatories, proposes that for the 50th anniversary of IGY, the worldwide scientific community should endorse and promote an electronic Geophysical Year (eGY) initiative. The proposed eGY concept would both commemorate the IGY in 2007-2008 and provide a forward impetus to geophysics in 21st century, similar to that provided by the IGY fifty years ago. The IAGA task force strongly advocates: (1) Securing permission and release of existing data; (2) Creating access to information; and (3) Conversion of relevant analog data to digital form. The eGY concept embraces all available and upcoming geophysical data (e.g., atmospheric, ionospheric, geomagnetic, gravity, etc.) through the establishment of a series of virtual geophysical observatories now being `'deployed'' in cyberspace. The eGY concept is modern, global, and timely; it is attractive, pragmatic, and affordable. The eGY is based on the existing and continually developing computing/networking technologies (e.g., XML, Semantic Web

Notes on the history of geophysics in the Ottoman Empire

Science.gov (United States)

Ozcep, F.; Ozcep, T.

2014-09-01

In Anatolia, the history of geophysical sciences may go back to antiquity (600 BC), namely the period when Thales lived in Magnesia (Asia Minor). In the modern sense, geophysics started with geomagnetic works in the 1600s. The period between 1600 and 1800 includes the measurement of magnetic declination, inclination and magnetic field strength. Before these years, there is a little information, such as how to use a compass, in the Kitab-i Bahriye (the Book of Navigation) of Piri Reis, who is one of the most important mariners of the Ottoman Empire. However, this may not mean that magnetic declination was generally understood. The first scientific book relating to geophysics is the book Fuyuzat-i Miknatissiye that was translated by Ibrahim Müteferrika and printed in 1731. The subject of this book is earth's magnetism. There is also information concerning geophysics in the book Cihannuma (Universal Geography) that was written by Katip Celebi and in the book Marifetname written by Ibrahim Hakki Erzurumlu, but these books are only partly geophysical books. In Istanbul the year 1868 is one of the most important for geophysical sciences because an observatory called Rasathane-i Amire was installed in the Pera region of this city. At this observatory the first systematic geophysical observations such as meteorological, seismological and even gravimetrical were made. There have been meteorological records in Anatolia since 1839. These are records of atmospheric temperature, pressure and humidity. In the Ottoman Empire, the science of geophysics is considered as one of the natural sciences along with astronomy, mineralogy, geology, etc., and these sciences are included as a part of physics and chemistry.

Abnormal sound detection device

International Nuclear Information System (INIS)

Yamada, Izumi; Matsui, Yuji.

1995-01-01

Only components synchronized with rotation of pumps are sampled from detected acoustic sounds, to judge the presence or absence of abnormality based on the magnitude of the synchronized components. A synchronized component sampling means can remove resonance sounds and other acoustic sounds generated at a synchronously with the rotation based on the knowledge that generated acoustic components in a normal state are a sort of resonance sounds and are not precisely synchronized with the number of rotation. On the other hand, abnormal sounds of a rotating body are often caused by compulsory force accompanying the rotation as a generation source, and the abnormal sounds can be detected by extracting only the rotation-synchronized components. Since components of normal acoustic sounds generated at present are discriminated from the detected sounds, reduction of the abnormal sounds due to a signal processing can be avoided and, as a result, abnormal sound detection sensitivity can be improved. Further, since it is adapted to discriminate the occurrence of the abnormal sound from the actually detected sounds, the other frequency components which are forecast but not generated actually are not removed, so that it is further effective for the improvement of detection sensitivity. (N.H.)

Can a single-shot black-blood T2-weighted spin-echo echo-planar imaging sequence with sensitivity encoding replace the respiratory-triggered turbo spin-echo sequence for the liver? An optimization and feasibility study.

Science.gov (United States)

Hussain, Shahid M; De Becker, Jan; Hop, Wim C J; Dwarkasing, Soendersing; Wielopolski, Piotr A

2005-03-01

To optimize and assess the feasibility of a single-shot black-blood T2-weighted spin-echo echo-planar imaging (SSBB-EPI) sequence for MRI of the liver using sensitivity encoding (SENSE), and compare the results with those obtained with a T2-weighted turbo spin-echo (TSE) sequence. Six volunteers and 16 patients were scanned at 1.5T (Philips Intera). In the volunteer study, we optimized the SSBB-EPI sequence by interactively changing the parameters (i.e., the resolution, echo time (TE), diffusion weighting with low b-values, and polarity of the phase-encoding gradient) with regard to distortion, suppression of the blood signal, and sensitivity to motion. The influence of each change was assessed. The optimized SSBB-EPI sequence was applied in patients (N = 16). A number of items, including the overall image quality (on a scale of 1-5), were used for graded evaluation. In addition, the signal-to-noise ratio (SNR) of the liver was calculated. Statistical analysis was carried out with the use of Wilcoxon's signed rank test for comparison of the SSBB-EPI and TSE sequences, with P = 0.05 considered the limit for significance. The SSBB-EPI sequence was improved by the following steps: 1) less frequency points than phase-encoding steps, 2) a b-factor of 20, and 3) a reversed polarity of the phase-encoding gradient. In patients, the mean overall image quality score for the optimized SSBB-EPI (3.5 (range: 1-4)) and TSE (3.6 (range: 3-4)), and the SNR of the liver on SSBB-EPI (mean +/- SD = 7.6 +/- 4.0) and TSE (8.9 +/- 4.6) were not significantly different (P > .05). Optimized SSBB-EPI with SENSE proved to be feasible in patients, and the overall image quality and SNR of the liver were comparable to those achieved with the standard respiratory-triggered T2-weighted TSE sequence. (c) 2005 Wiley-Liss, Inc.

Aquifer Recharge Estimation In Unsaturated Porous Rock Using Darcian And Geophysical Methods.

Science.gov (United States)

Nimmo, J. R.; De Carlo, L.; Masciale, R.; Turturro, A. C.; Perkins, K. S.; Caputo, M. C.

2016-12-01

Within the unsaturated zone a constant downward gravity-driven flux of water commonly exists at depths ranging from a few meters to tens of meters depending on climate, medium, and vegetation. In this case a steady-state application of Darcy's law can provide recharge rate estimates.We have applied an integrated approach that combines field geophysical measurements with laboratory hydraulic property measurements on core samples to produce accurate estimates of steady-state aquifer recharge, or, in cases where episodic recharge also occurs, the steady component of recharge. The method requires (1) measurement of the water content existing in the deep unsaturated zone at the location of a core sample retrieved for lab measurements, and (2) measurement of the core sample's unsaturated hydraulic conductivity over a range of water content that includes the value measured in situ. Both types of measurements must be done with high accuracy. Darcy's law applied with the measured unsaturated hydraulic conductivity and gravitational driving force provides recharge estimates.Aquifer recharge was estimated using Darcian and geophysical methods at a deep porous rock (calcarenite) experimental site in Canosa, southern Italy. Electrical Resistivity Tomography (ERT) and Vertical Electrical Sounding (VES) profiles were collected from the land surface to water table to provide data for Darcian recharge estimation. Volumetric water content was estimated from resistivity profiles using a laboratory-derived calibration function based on Archie's law for rock samples from the experimental site, where electrical conductivity of the rock was related to the porosity and water saturation. Multiple-depth core samples were evaluated using the Quasi-Steady Centrifuge (QSC) method to obtain hydraulic conductivity (K), matric potential (ψ), and water content (θ) estimates within this profile. Laboratory-determined unsaturated hydraulic conductivity ranged from 3.90 x 10-9 to 1.02 x 10-5 m

Monitoring and Quantifying Subsurface Ice and Water Content in Permafrost Regions Based on Geophysical Data Sets

Science.gov (United States)

Hauck, C.; Bach, M.; Hilbich, C.

2007-12-01

Based on recent observational evidence of climate change in permafrost regions, it is now recognised that a detailed knowledge of the material composition of the subsurface in permafrost regions is required for modelling of the future evolution of the ground thermal regime and an assessment of the hazard potential due to degrading permafrost. However, due to the remote location of permafrost areas and the corresponding difficulties in obtaining high-quality data sets of the subsurface, knowledge about the material composition in permafrost areas is scarce. In frozen ground subsurface material may consist of four different phases: rock/soil matrix, unfrozen pore water, ice and air-filled pore space. Applications of geophysical techniques for determining the subsurface composition are comparatively cheap and logistically feasible alternatives to the single point information from boreholes. Due to the complexity of the subsurface a combination of complementary geophysical methods (e.g. electrical resistivity tomography (ERT) and refraction seismic tomography) is often favoured to avoid ambiguities in the interpretation of the results. The indirect nature of geophysical soundings requires a relation between the measured variable (electrical resistivity, seismic velocity) and the rock-, water-, ice- and air content. In this contribution we will present a model which determines the volumetric fractions of these four phases from tomographic electrical and seismic data sets. The so-called 4-phase model is based on two well-known geophysical mixing rules using observed resistivity and velocity data as input data on a 2-dimensional grid. Material properties such as resistivity and P- wave velocity of the host rock material and the pore water have to be known beforehand. The remaining free model parameters can be determined by a Monte-Carlo approach, the results of which are used additionally as indicator for the reliability of the model results. First results confirm the

EchoScan: A new system to objectively assess peripheral hearing disorders

Directory of Open Access Journals (Sweden)

Thomas Venet

2012-01-01

Full Text Available Pure-tone air-conduction audiometry (PTA is the reference clinical test used in Europe and the United States to measure the extent of hearing loss. It is a subjective, behavioral test, which measures thresholds of hearing sensations and perceptions based on patient responses to frequency-specific pure-tone stimuli. PTA can detect hearing problems due to cochlear or retro-cochlear impairment, without identifying the source of the problem. In contrast, cubic distortion product otoacoustic emissions (DPOAEs detect inner-ear dysfunctions, particularly those involving the outer hair cells sensitive to noise and ototoxicants. Recently, ototoxicants were shown to have an action on the central nuclei driving the middle-ear acoustic reflex. Therefore, a new device, called EchoScan, was conceived to collect and measure performance both in the middle- and inner-ear. Its originality: the use of a battery of DPOAE measurements associated with contra-lateral acoustic stimulation. Changes in DPOAE amplitude due to ageing and gender were incidentally detected and EchoScan was more sensitive than impedancemetry to detect the stapedial reflex. EchoScan can be used both in clinical investigations and in occupational medicine, especially for the auditory follow-up of people exposed to noise or ototoxic agents. EchoScan could be promising to assess early detection in programs to prevent hearing loss.

Seabed sediment classification for monitoring underwater nourishments using time series of multi-beam echo-soundings

Science.gov (United States)

Gaida, T. C.; Snellen, M.; van Dijk, T. A. G. P.; Simons, D. G.

2017-12-01

Coastal erosion induced by natural processes, such as wind, waves, tidal currents, or human interferences endangers human beings, infrastructure, fauna and flora at the oceans and rivers all over the world. In The Netherlands, in particular the North Sea islands are strongly affected by sediment erosion. To protect and stabilize the coastline, beach and shoreface nourishments are frequently performed. Thereby, sediment reservoirs are created that replace the eroded sediments. Increasing the long-term efficiency of coastal protection requires monitoring of the temporal and spatial development of the coastal nourishments. Multi-beam echo-sounders (MBES) allow for detailed and comprehensive investigations of the seabed composition and structure. To investigate the potential of using MBES for monitoring nourishments in a tidal inlet, four MBES surveys per year are carried out at the Dutch Wadden island Ameland. A pre-nourishment MBES survey was performed in April 2017 and the subsequent post-nourishment survey will take place in September 2017. Both surveys are equipped with a Kongsberg EM 2040C dual-head MBES and are supported with extensive grab sampling. In this study the use of MBES backscatter and bathymetry data are considered as an approach for monitoring coastal nourishments. The aim is to develop a monitoring procedure that allows for comparing MBES data taken during different surveys, i.e., with variations in environmental conditions, MBES characteristics and acquisition procedures. Different unsupervised and supervised acoustic seafloor classification techniques are applied to the processed MBES data to classify the seabed sediments. The analysis of the pre-nourishment MBES data indicates that the backscatter and consequently the classification are highly driven by the abundancy of shell fragments. These results will be used as a baseline to investigate the accumulation of the underwater nourishments. Independent grab samples will be used to select the

Self-calibrated multiple-echo acquisition with radial trajectories using the conjugate gradient method (SMART-CG).

Science.gov (United States)

Jung, Youngkyoo; Samsonov, Alexey A; Bydder, Mark; Block, Walter F

2011-04-01

To remove phase inconsistencies between multiple echoes, an algorithm using a radial acquisition to provide inherent phase and magnitude information for self correction was developed. The information also allows simultaneous support for parallel imaging for multiple coil acquisitions. Without a separate field map acquisition, a phase estimate from each echo in multiple echo train was generated. When using a multiple channel coil, magnitude and phase estimates from each echo provide in vivo coil sensitivities. An algorithm based on the conjugate gradient method uses these estimates to simultaneously remove phase inconsistencies between echoes, and in the case of multiple coil acquisition, simultaneously provides parallel imaging benefits. The algorithm is demonstrated on single channel, multiple channel, and undersampled data. Substantial image quality improvements were demonstrated. Signal dropouts were completely removed and undersampling artifacts were well suppressed. The suggested algorithm is able to remove phase cancellation and undersampling artifacts simultaneously and to improve image quality of multiecho radial imaging, the important technique for fast three-dimensional MRI data acquisition. Copyright © 2011 Wiley-Liss, Inc.

Spin-Echo Small-Angle Neutron Scattering Development

NARCIS (Netherlands)

Uca, O.

2003-01-01

Spin-Echo Small-Angle Neutron Scattering (SESANS) instrument is a novel SANS technique which enables one to characterize distances from a few nanometers up to the micron range. The most striking difference between normal SANS and SESANS is that in SESANS one gets information in real space, whereas

A theoretical study of special acoustic effects caused by the staircase of the El Castillo pyramid at the Maya ruins of Chichen-Itza in Mexico

Science.gov (United States)

Declercq, Nico F.; Degrieck, Joris; Briers, Rudy; Leroy, Oswald

2004-12-01

It is known that a handclap in front of the stairs of the great pyramid of Chichen Itza produces a chirp echo which sounds more or less like the sound of a Quetzal bird. The present work describes precise diffraction simulations and attempts to answer the critical question what physical effects cause the formation of the chirp echo. Comparison is made with experimental results obtained from David Lubman. Numerical simulations show that the echo shows a strong dependence on the kind of incident sound. Simulations are performed for a (delta function like) pulse and also for a real handclap. The effect of reflections on the ground in front of the pyramid is also discussed. The present work also explains why an observer seated on the lowest step of the pyramid hears the sound of raindrops falling in a water filled bucket instead of footstep sounds when people, situated higher up the pyramid, climb the stairs. .

Geophysical characterization from Itu intrusive suite

International Nuclear Information System (INIS)

Pascholati, M.E.

1989-01-01

The integrated use of geophysical, geological, geochemical, petrographical and remote sensing data resulted in a substantial increase in the knowledge of the Itu Intrusive Suite. The main geophysical method was gamma-ray spectrometry together with fluorimetry and autoradiography. Three methods were used for calculation of laboratory gamma-ray spectrometry data. For U, the regression method was the best one. For K and Th, equations system and absolute calibration presented the best results. Surface gamma-ray spectrometry allowed comparison with laboratory data and permitted important contribution to the study of environmental radiation. (author)

A portable marine geophysical data access and management system

Digital Repository Service at National Institute of Oceanography (India)

Kunte, P.D.; Narvekar, P.

Geophysical Oracle Database Management System (GPODMS) that is residing on UNIX True 64 Compaq Alpha server. GPODMS is a stable Oracle database system for longterm storage and systematic management of geophysical data and information of various disciplines...