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1

A Multimodal Approach to Image-Derived Input Functions for Brain PET  

PubMed Central

Many methods have been proposed for generating an image-derived input function (IDIF) exclusively from PET images. The purpose of this study was to assess the viability of a multimodality approach utilizing registered MR images. 3T-MR and HRRT-PET data were acquired from human subjects. Segmentation of both the left and right carotid arteries was performed in MR images using a 3D level sets method. Vessel centerlines were extracted by parameterization of the segmented voxel coordinates with either a single polynomial curve or a B-spline curve fitted to the segmented data. These centerlines were subsequently re-registered to static PET data to maximize the accurate classification of PET voxels in the ROI. The accuracy of this approach was assessed by comparison of the area under the curve (AUC) of the IDIF to that measured from conventional automated arterial blood sampling. Our method produces curves similar in shape to that of blood sampling. The mean AUC ratio of the centerline region was 0.40±0.19 before re-registration and 0.69±0.26 after re-registration. Increasing the diameter of the carotid ROI produced a smooth reduction in AUC. Thus, even with the high resolution of the HRRT, partial volume correction is still necessary. This study suggests that the combination of PET information with MR segmented regions will demonstrate an improvement over regions based solely on MR or PET alone.

Fung, Edward K.; Planeta-Wilson, Beata; Mulnix, Tim; Carson, Richard E.

2010-01-01

2

Noninvasive image derived heart input function for CMRglc measurements in small animal slow infusion FDG PET studies.  

PubMed

Absolute quantitation of the cerebral metabolic rate for glucose (CMRglc) can be obtained in positron emission tomography (PET) studies when serial measurements of the arterial [(18)F]-fluoro-deoxyglucose (FDG) input are available. Since this is not always practical in PET studies of rodents, there has been considerable interest in defining an image-derived input function (IDIF) by placing a volume of interest (VOI) within the left ventricle of the heart. However, spill-in arising from trapping of FDG in the myocardium often leads to progressive contamination of the IDIF, which propagates to underestimation of the magnitude of CMRglc. We therefore developed a novel, non-invasive method for correcting the IDIF without scaling to a blood sample. To this end, we first obtained serial arterial samples and dynamic FDG-PET data of the head and heart in a group of eight anaesthetized rats. We fitted a bi-exponential function to the serial measurements of the IDIF, and then used the linear graphical Gjedde-Patlak method to describe the accumulation in myocardium. We next estimated the magnitude of myocardial spill-in reaching the left ventricle VOI by assuming a Gaussian point-spread function, and corrected the measured IDIF for this estimated spill-in. Finally, we calculated parametric maps of CMRglc using the corrected IDIF, and for the sake of comparison, relative to serial blood sampling from the femoral artery. The uncorrected IDIF resulted in 20% underestimation of the magnitude of CMRglc relative to the gold standard arterial input method. However, there was no bias with the corrected IDIF, which was robust to the variable extent of myocardial tracer uptake, such that there was a very high correlation between individual CMRglc measurements using the corrected IDIF with gold-standard arterial input results. Based on simulation, we furthermore find that electrocardiogram-gating, i.e. ECG-gating is not necessary for IDIF quantitation using our approach. PMID:23160517

Xiong, Guoming; Paul, Cumming; Todica, Andrei; Hacker, Marcus; Bartenstein, Peter; Böning, Guido

2012-12-01

3

Noninvasive image derived heart input function for CMRglc measurements in small animal slow infusion FDG PET studies  

NASA Astrophysics Data System (ADS)

Absolute quantitation of the cerebral metabolic rate for glucose (CMRglc) can be obtained in positron emission tomography (PET) studies when serial measurements of the arterial [18F]-fluoro-deoxyglucose (FDG) input are available. Since this is not always practical in PET studies of rodents, there has been considerable interest in defining an image-derived input function (IDIF) by placing a volume of interest (VOI) within the left ventricle of the heart. However, spill-in arising from trapping of FDG in the myocardium often leads to progressive contamination of the IDIF, which propagates to underestimation of the magnitude of CMRglc. We therefore developed a novel, non-invasive method for correcting the IDIF without scaling to a blood sample. To this end, we first obtained serial arterial samples and dynamic FDG-PET data of the head and heart in a group of eight anaesthetized rats. We fitted a bi-exponential function to the serial measurements of the IDIF, and then used the linear graphical Gjedde-Patlak method to describe the accumulation in myocardium. We next estimated the magnitude of myocardial spill-in reaching the left ventricle VOI by assuming a Gaussian point-spread function, and corrected the measured IDIF for this estimated spill-in. Finally, we calculated parametric maps of CMRglc using the corrected IDIF, and for the sake of comparison, relative to serial blood sampling from the femoral artery. The uncorrected IDIF resulted in 20% underestimation of the magnitude of CMRglc relative to the gold standard arterial input method. However, there was no bias with the corrected IDIF, which was robust to the variable extent of myocardial tracer uptake, such that there was a very high correlation between individual CMRglc measurements using the corrected IDIF with gold-standard arterial input results. Based on simulation, we furthermore find that electrocardiogram-gating, i.e. ECG-gating is not necessary for IDIF quantitation using our approach.

Xiong, Guoming; Cumming, Paul; Todica, Andrei; Hacker, Marcus; Bartenstein, Peter; Böning, Guido

2012-12-01

4

Cerebral blood flow with [15O]water PET studies using an image-derived input function and MR-defined carotid centerlines  

NASA Astrophysics Data System (ADS)

Full quantitative analysis of brain PET data requires knowledge of the arterial input function into the brain. Such data are normally acquired by arterial sampling with corrections for delay and dispersion to account for the distant sampling site. Several attempts have been made to extract an image-derived input function (IDIF) directly from the internal carotid arteries that supply the brain and are often visible in brain PET images. We have devised a method of delineating the internal carotids in co-registered magnetic resonance (MR) images using the level-set method and applying the segmentations to PET images using a novel centerline approach. Centerlines of the segmented carotids were modeled as cubic splines and re-registered in PET images summed over the early portion of the scan. Using information from the anatomical center of the vessel should minimize partial volume and spillover effects. Centerline time-activity curves were taken as the mean of the values for points along the centerline interpolated from neighboring voxels. A scale factor correction was derived from calculation of cerebral blood flow (CBF) using gold standard arterial blood measurements. We have applied the method to human subject data from multiple injections of [15O]water on the HRRT. The method was assessed by calculating the area under the curve (AUC) of the IDIF and the CBF, and comparing these to values computed using the gold standard arterial input curve. The average ratio of IDIF to arterial AUC (apparent recovery coefficient: aRC) across 9 subjects with multiple (n = 69) injections was 0.49 ± 0.09 at 0-30 s post tracer arrival, 0.45 ± 0.09 at 30-60 s, and 0.46 ± 0.09 at 60-90 s. Gray and white matter CBF values were 61.4 ± 11.0 and 15.6 ± 3.0 mL/min/100 g tissue using sampled blood data. Using IDIF centerlines scaled by the average aRC over each subjects’ injections, gray and white matter CBF values were 61.3 ± 13.5 and 15.5 ± 3.4 mL/min/100 g tissue. Using global average aRC values, the means were unchanged, and intersubject variability was noticeably reduced. This MR-based centerline method with local re-registration to [15O]water PET yields a consistent IDIF over multiple injections in the same subject, thus permitting the absolute quantification of CBF without arterial input function measurements.

Fung, Edward K.; Carson, Richard E.

2013-03-01

5

Non-invasive assessment of skeletal kinetics using fluorine-18 fluoride positron emission tomography: evaluation of image and population-derived arterial input functions.  

PubMed

To measure regional skeletal kinetics using fluorine-18 fluoride positron emission tomography (PET) it is necessary to know the concentration of radioactive tracer being delivered to bone by arterial plasma with relation to time, the arterial input function (IFa). Methods by which IFa can be derived without arterial sampling are attractive because of their relative technical simplicity and the reduction in possible morbidity to the subject. We have compared the use of a scaled population input function (IFp) and a corrected image-derived input function from the aorta (IFi) with an IFa directly measured from a radial artery line in ten normal postmenopausal women. Both of the aforementioned methods rely only on a small number of discrete venous samples. Each subject had a dynamic PET acquisition of the lumbar spine performed after the intravenous injection of 180 MBq (18)F-fluoride. Both the IFp and the IFi were compared with the IFa in terms of the accuracy of determination of six parameters. These were: plasma clearance of fluoride to bone mineral (K(i)), unidirectional plasma clearance to total bone tissue (K(1)) and individual rate constants k(2), k(3) and k(4), calculated using non-linear regression with a three-compartment model, and the plasma clearance to bone mineral calculated using the Patlak method (K(pat)). For both the IFp and the IFi method the root mean square errors for K(pat) and K(i) were similar and small (<8.2%). The errors in determining K(1) and the rate constants k(2) to k(4) are larger by either method, but with a small advantage using the IFp method. It is concluded that the use of either non-invasive method for determining the arterial plasma input function is suitable for the measurement of the most important parameters, K(i) and K(pat), in these subjects. PMID:10552083

Cook, G J; Lodge, M A; Marsden, P K; Dynes, A; Fogelman, I

1999-11-01

6

Calibrated image-derived input functions for the determination of the metabolic uptake rate of glucose with [18F]-FDG PET  

PubMed Central

Purpose We investigated the use of a simple calibration method to remove bias in previously proposed approaches to image-derived input functions (IDIFs) when used to calculate the metabolic uptake rate of glucose (Km) from dynamic [18F]-FDG PET scans of the thigh. Our objective was to obtain nonbiased, low-variance Km values without blood sampling. Materials and methods We evaluated eight previously proposed IDIF methods. Km values derived from these IDIFs were compared with Km values calculated from the arterial blood samples (gold standard). We used linear regression to extract calibration parameters to remove bias. Following calibration, cross-validation and bootstrapping were used to estimate the mean square error and variance. Results Three of the previously proposed methods failed mainly because of zero-crossings of the IDIF. The remaining five methods were improved by calibration, yielding unbiased Km values. The method with the lowest SD yielded an SD of 0.0017/min – that is, below 10% of the muscle Km value in this study. Conclusion Previously proposed IDIF methods can be improved by using a simple calibration procedure. The calibration procedure may be used in other studies, thus obviating the need for arterial blood sampling, once the calibration parameters have been established in a subgroup of participants. The method has potential for use in other parts of the body as it is robust with regard to partial volume effects.

Reichkendler, Michala H.; Larsen, Rasmus; Auerbach, Pernille; H?jgaard, Liselotte; Nielsen, Henning B.; Ploug, Thorkil; Stallknecht, Bente; Holm, S?ren

2014-01-01

7

Guiding an image acquisition strategy: MODIS-derived growing season timing and cloud cover probability as inputs to a global agriculture monitoring (GEO-GLAM) system of systems  

NASA Astrophysics Data System (ADS)

Satellite remote sensing is an invaluable tool in the collection of data and generation of information about global agricultural production and food security. In order to secure the necessary image acquisitions for these global agricultural monitoring applications, we must first articulate Earth observation (EO) requirements for the diverse agricultural landscapes and cropping systems which cover the land surface. Crucial to this task are the identification of growing season timing at a meaningful spatial scale, so as to better define the necessary periods of image acquisition, as well as the determination of the likelihood of a cloud-free observation during different portions of the agricultural growing season. To this end, ten years of MODIS imagery have been used to determine phenological transition dates (start, peak, and end of season) and their ranges over that time period at 0.5 degree globally. This is the first set of global, satellite-derived, cropland-specific calendar dates. Because cloud cover presents a temporally and spatially heterogeneous obstacle in optical remote sensing of many important agricultural areas, roughly a decade of MODIS observations have been used to determine the likelihood of a cloud-free observation during different portions of the agricultural growing season at 0.05 degree. This research shows persistent cloud cover during crucial portions of the growing season for some important agricultural regions, information which can be used to better define the actual repeat time required to obtain a valid acquisition and provides evidence for a constellation approach for Earth observations for agricultural monitoring. Coupled with the growing season calendars, this research provides important inputs to agricultural production and food security monitoring in the context of the Global Agricultural Monitoring initiative (GEO-GLAM), an effort by the Group on Earth Observations (GEO) to synergize existing national and regional observation systems for improved agricultural production and food security monitoring.

Whitcraft, A. K.; Vermote, E.

2012-12-01

8

Non-invasive assessment of skeletal kinetics using fluorine-18 fluoride positron emission tomography: evaluation of image and population-derived arterial input functions  

Microsoft Academic Search

.   To measure regional skeletal kinetics using fluorine-18 fluoride positron emission tomography (PET) it is necessary to know\\u000a the concentration of radioactive tracer being delivered to bone by arterial plasma with relation to time, the arterial input\\u000a function (IFa). Methods by which IFa can be derived without arterial sampling are attractive because of their relative technical\\u000a simplicity and the reduction

Gary J. R. Cook; Martin A. Lodge; Paul K. Marsden; Angela Dynes; Ignac Fogelman

1999-01-01

9

Removing the input derivatives in the generalized bilinear state equations  

Microsoft Academic Search

The paper suggests constraints on the coefficients ai, bi, ci j of the bilinear continuous-time input-output model that yield generalized state equations with input derivative order lower than that in the input-output equations. In the limiting case when one removes the input derivatives altogether, these conditions provide a solution of the realizability problem. The new state coordinates are found step

Tanel Mullari; Ü Kotta; P Kotta; M Tõnso; A S Zinober

2009-01-01

10

Multiple-input fiber optic imaging system  

NASA Astrophysics Data System (ADS)

Fiber optic imaging bundles have been used for a number of years in medical and industrial remote sensing applications. Several NASA applications (such as Orbiter payload alignment for berthing/unberthing operations and Space Station Freedom construction) requiring multiple views have been identified. This paper reports on some of the proposed systems and on an optical switch which can connect any one of multiple imaging bundles to a single camera. The switch uses a rotating offset prism and collimated optics to relay the image to the camera. The offset prism merely displaces the image without dispersing, thereby acting as a periscope. By operating the prism in collimated light any one of several imaging bundles can be selected with negligible sensitivity to rotational precision. Located in the Orbiter payload bay, the input view would be selected by driving motors to rotate the prism. The same motors, used in a feedback mode, would be used to `stop-down' the input optics. Detailed mechanical and optical designs are presented as well as results from developmental studies.

Faller, Carlton S.; Ehrhardt, Mark W.; Monroe, Stanley E.; Juday, Richard D.

1993-09-01

11

PRINCIPLES OF TOMOGRAPHICAL IMAGING WITH LIMITED-ANGLE INPUT  

SciTech Connect

The theory of tomographical imaging with limited-angular input is discussed , from which two reconstruction algorithms are derived. The existence of missing information due to incomplete angular coverage is demonstrated. and an iteration algorithm to recover this information from a priori knowledge on the finite extent of the object developed. Smoothing algorithms to stabilize reconstructions in the presence of noise are given. The effects of digitization and finite truncation of the reconstruction region in numerical computation are also analysed. It is shown that the limited-angle problem is governed by a set of eigenvalues whose spectrum is determined by the imaging angle and the finite extent of the object. The distortion on a point source caused by the missing information is calculated; from the results some properties of the iteration scheme, such as spatial uniformity, are derived.

Tam, K. C.; Perez-Mendez, V.

1980-09-01

12

Fuzzy vision - Multiple inputs speed image understanding  

NASA Technical Reports Server (NTRS)

The fuzzy vision system designed for the interpretation of multiple successive images is described. The system is noise insensitive and can be mapped directly onto parallel processing hardware. The system consists of a region generator and a viewer which access a common semantic net; the components and operation of these subsystems are examined. The advantages and disadvantages of the fuzzy vision system are discussed. Diagrams of the region generator, viewer, and a semantic net are provided. An example depicting the operation of the fuzzy vision system is presented.

Meier, R. J., Jr.

1985-01-01

13

A kinetic and 3D image input device  

Microsoft Academic Search

Gesture recognition in real time can bridge a gap between humans and computers. Object segmentation from the background is a critical problem in the conventional gesture recognition technology. We have developed a new input device which can detect a kinetic and 3D image of a hand in real time. We call it “Motion Processor”. The Motion Processor with infrared light

Shunichi Numazaki; Akira Morishita; Naoko Umeki; Minoru Ishikawa; Miwako Doi

1998-01-01

14

Noninvasive Quantification of the Cerebral Metabolic Rate for Glucose Using Positron Emission Tomography, 18F-Fluoro-2Deoxyglucose, the Patlak Method, and an Image-Derived Input Function  

Microsoft Academic Search

The authors developed and tested a method for the noninvasive quantification of the cerebral metabolic rate for glucose (CMRglc) using positron emission tomography (PET), 18F-fluoro-2-deoxyglucose, the Patlak method, and an imagederived input function. Dynamic PET data acquired 12 to 48 seconds after rapid tracer injection were summed to identify carotid artery regions of interest (ROIs). The input function then was

Kewei Chen; Daniel Bandy; Eric Reiman; Sung-Cheng Huang; Michael Lawson; Dagan Feng; Lang-sheng Yun; Anita Palant

1998-01-01

15

A field study of the effects of agriculturally derived insecticide input on stream macroinvertebrate dynamics  

Microsoft Academic Search

Information about the effects of agriculturally derived insecticide input on the aquatic fauna in the field is sparse. Runoff-related insecticide input and the resulting toxicological effects on the aquatic fauna (abundance, drift, emergence) at three sampling sites at different distances (450–1150 m) from the input location of contaminated edge-of-field runoff (erosion rill) were investigated. By means of event-triggered sampling it

Ralf Schulz; Mathias Liess

1999-01-01

16

Approach for Input Uncertainty Propagation and Robust Design in CFD Using Sensitivity Derivatives  

NASA Technical Reports Server (NTRS)

An implementation of the approximate statistical moment method for uncertainty propagation and robust optimization for quasi 3-D Euler CFD code is presented. Given uncertainties in statistically independent, random, normally distributed input variables, first- and second-order statistical moment procedures are performed to approximate the uncertainty in the CFD output. Efficient calculation of both first- and second-order sensitivity derivatives is required. In order to assess the validity of the approximations, these moments are compared with statistical moments generated through Monte Carlo simulations. The uncertainties in the CFD input variables are also incorporated into a robust optimization procedure. For this optimization, statistical moments involving first-order sensitivity derivatives appear in the objective function and system constraints. Second-order sensitivity derivatives are used in a gradient-based search to successfully execute a robust optimization. The approximate methods used throughout the analyses are found to be valid when considering robustness about input parameter mean values.

Putko, Michele M.; Taylor, Arthur C., III; Newman, Perry A.; Green, Lawrence L.

2002-01-01

17

Noninvasive estimation of the arterial input function in positron emission tomography imaging of cerebral blood flow  

PubMed Central

Positron emission tomography (PET) with 15O-labeled water can provide reliable measurement of cerebral blood flow (CBF). Quantification of CBF requires knowledge of the arterial input function (AIF), which is usually provided by arterial blood sampling. However, arterial sampling is invasive. Moreover, the blood generally is sampled at the wrist, which does not perfectly represent the AIF of the brain, because of the effects of delay and dispersion. We developed and validated a new noninvasive method to obtain the AIF directly by PET imaging of the internal carotid artery in a region of interest (ROI) defined by coregistered high-resolution magnetic resonance angiography. An ROI centered at the petrous portion of the internal carotid artery was defined, and the AIF was estimated simultaneously with whole brain blood flow. The image-derived AIF (IDAIF) method was validated against conventional arterial sampling. The IDAIF generated highly reproducible CBF estimations, generally in good agreement with the conventional technique.

Su, Yi; Arbelaez, Ana M; Benzinger, Tammie L S; Snyder, Abraham Z; Vlassenko, Andrei G; Mintun, Mark A; Raichle, Marcus E

2013-01-01

18

The Fluoroscopic Image as Input Data for Computed Tomography  

Microsoft Academic Search

The use of a fluoroscopic imaging system for providing the projection data required in computerized tomography has been explored. The capability of both conventional systems and large flat screen-low light level vidio systems are discussed. The highlights of previously published data are also presented. Specific applications to radiation therapy are illustrated and the equipment described. The differential contrast senditivity is

Norman A. Baily

1979-01-01

19

On the Derivation of Input Parameters for Urban Canopy Models from Urban Morphological Datasets  

NASA Astrophysics Data System (ADS)

Two techniques are analysed to derive mean street width and mean building width from morphological data of real cities: one based on a two-dimensional simplified morphology, and the other based on a three-dimensional regular simplified morphology. For each simplified morphology (two-dimensional and three-dimensional), the sky-view factors (street-to-sky) are computed and compared with the sky-view factors derived from the real morphology for selected districts of three European and two North American cities. The two-dimensional simplified morphology reproduces the real sky-view factors better than the three-dimensional morphology. Since many urban canopy parameterizations represent the city using simplified morphologies, this can be useful information for the derivation of input parameters for urban canopy parameterizations from real morphological data.

Martilli, Alberto

2009-02-01

20

The effect of input data transformations on object-based image analysis  

PubMed Central

The effect of using spectral transform images as input data on segmentation quality and its potential effect on products generated by object-based image analysis are explored in the context of land cover classification in Accra, Ghana. Five image data transformations are compared to untransformed spectral bands in terms of their effect on segmentation quality and final product accuracy. The relationship between segmentation quality and product accuracy is also briefly explored. Results suggest that input data transformations can aid in the delineation of landscape objects by image segmentation, but the effect is idiosyncratic to the transformation and object of interest.

LIPPITT, CHRISTOPHER D.; COULTER, LLOYD L.; FREEMAN, MARY; LAMANTIA-BISHOP, JEFFREY; PANG, WYSON; STOW, DOUGLAS A.

2011-01-01

21

Effects of Ground Motion Input on the Derived Fragility Functions: Case study of 2010 Haiti Earthquake  

NASA Astrophysics Data System (ADS)

Empirical fragility functions are derived by statistical processing of the data on: i) Damaged and undamaged buildings, and ii) Ground motion intensity values at the buildings' locations. This study investigates effects of different ground motion inputs on the derived fragility functions. The previously constructed fragility curves (Hancilar et al. 2013), which rely on specific shaking intensity maps published by the USGS after the 2010 Haiti Earthquake, are compared with the fragility functions computed in the present study. Building data come from field surveys of 6,347 buildings that are grouped with respect to structural material type and number of stories. For damage assessment, the European Macroseismic Scale (EMS-98) damage grades are adopted. The simplest way to account for the variability in ground motion input could have been achieved by employing different ground motion prediction equations (GMPEs) and their standard variations. However, in this work, we prefer to rely on stochastically simulated ground motions of the Haiti earthquake. We employ five different source models available in the literature and calculate the resulting strong ground motion in time domain. In our simulations we also consider the local site effects by published studies on NEHRP site classes and micro-zoning maps of the city of Port-au-Prince. We estimate the regional distributions from the waveforms simulated at the same coordinates that we have damage information from. The estimated spatial distributions of peak ground accelerations and velocities, PGA and PGV respectively, are then used as input to fragility computations. The results show that changing the ground motion input causes significant variability in the resulting fragility functions.

Hancilar, Ufuk; Harmandar, Ebru; Çakti, Eser

2014-05-01

22

Exploring 2D\\/3D Input Techniques for Medical Image Analysis  

Microsoft Academic Search

We describe a series of experiments that compared the 2D and 3D input methods for selection and positioning tasks related to medical image analysis. For this study, we chose a switchable P5 glove controller, which can be used to provide both 2DOF and 6DOF input control. Our results suggest that for both tasks the overall completion time and accuracy can

E. Zudilova-Seinstra; P. Sloot; P. de Koning; A. Suinesiaputra; R. van der Geest; J. Reiber

2009-01-01

23

Evaluation of 2D and 3D glove input applied to medical image analysis  

Microsoft Academic Search

We describe a series of experiments that compared 2D\\/3D input methods for selection and positioning tasks related to medical image analysis. For our study, we chose a switchable P5 Glove Controller, which can be used to provide both 2DOF and 6DOF input control. Our results suggest that for both tasks the overall performance and accuracy can be improved when the

Elena V. Zudilova-Seinstra; Patrick J. H. de Koning; Avan Suinesiaputra; Boris W. van Schooten; Rob J. van der Geest; Johan H. C. Reiber; Peter M. A. Sloot

2010-01-01

24

Exploring 2D\\/3D input techniques for medical image analysis  

Microsoft Academic Search

We describe a series of experiments that compared the 2D and 3D input methods for selection and positioning tasks related to medical image analysis. For this study, we chose a switchable P5 glove controller, which can be used to provide both 2DOF and 6DOF input control. Our results suggest that for both tasks the overall completion time and accuracy can

E. V. Zudilova-Seinstra; P. M. A. Sloot; Koning de P. J. H; A. Suinesiaputra; Geest van der R. J; J. H. C. Reiber

2010-01-01

25

Maximum likelihood identification and optimal input design for identifying aircraft stability and control derivatives  

NASA Technical Reports Server (NTRS)

A new method of extracting aircraft stability and control derivatives from flight test data is developed based on the maximum likelihood cirterion. It is shown that this new method is capable of processing data from both linear and nonlinear models, both with and without process noise and includes output error and equation error methods as special cases. The first application of this method to flight test data is reported for lateral maneuvers of the HL-10 and M2/F3 lifting bodies, including the extraction of stability and control derivatives in the presence of wind gusts. All the problems encountered in this identification study are discussed. Several different methods (including a priori weighting, parameter fixing and constrained parameter values) for dealing with identifiability and uniqueness problems are introduced and the results given. The method for the design of optimal inputs for identifying the parameters of linear dynamic systems is also given. The criterion used for the optimization is the sensitivity of the system output to the unknown parameters. Several simple examples are first given and then the results of an extensive stability and control dervative identification simulation for a C-8 aircraft are detailed.

Stepner, D. E.; Mehra, R. K.

1973-01-01

26

Fluorescein Derivatives in Intravital Fluorescence Imaging  

PubMed Central

Intravital fluorescence microscopy enables the direct imaging of fluorophores in vivo and advanced techniques such as fluorescence lifetime imaging (FLIM) enable the simultaneous detection of multiple fluorophores. Consequently, it is now possible to record distribution and metabolism of a chemical in vivo and to optimise the delivery of fluorophores in vivo. Recent clinical applications with fluorescein and other intravital fluorescent stains have occurred in neurosurgery, dermatology [including photodynamic therapy (PDT)] and endomicroscopy. Potential uses have been identified in periodontal disease, skin graft and cancer surgery. Animal studies have demonstrated that diseased tissue can be specifically stained with fluorophore conjugates. This review focuses on the fluorescein derived fluorophores in common clinical use and provides examples of novel applications from studies in tissue samples.

Robertson, Thomas A.; Bunel, Florestan; Roberts, Michael S.

2013-01-01

27

Image Deblurring Using Derivative Compressed Sensing for Optical Imaging Application  

NASA Astrophysics Data System (ADS)

Reconstruction of multidimensional signals from the samples of their partial derivatives is known to be a standard problem in inverse theory. Such and similar problems routinely arise in numerous areas of applied sciences, including optical imaging, laser interferometry, computer vision, remote sensing and control. Though being ill-posed in nature, the above problem can be solved in a unique and stable manner, provided proper regularization and relevant boundary conditions. In this paper, however, a more challenging setup is addressed, in which one has to recover an image of interest from its noisy and blurry version, while the only information available about the imaging system at hand is the amplitude of the generalized pupil function (GPF) along with partial observations of the gradient of GPF's phase. In this case, the phase-related information is collected using a simplified version of the Shack-Hartmann interferometer, followed by recovering the entire phase by means of derivative compressed sensing. Subsequently, the estimated phase can be combined with the amplitude of the GPF to produce an estimate of the point spread function (PSF), whose knowledge is essential for subsequent image deconvolution. In summary, the principal contribution of this work is twofold. First, we demonstrate how to simplify the construction of the Shack-Hartmann interferometer so as to make it less expensive and hence more accessible. Second, it is shown by means of numerical experiments that the above simplification and its associated solution scheme produce image reconstructions of the quality comparable to those obtained using dense sampling of the GPF phase.

Rostami, Mohammad; Michailovich, Oleg; Wang, Zhou

2012-07-01

28

Classifiers vs. input variables—The drivers in image classification for land cover mapping  

NASA Astrophysics Data System (ADS)

The study investigates the performance of image classifiers for landscape-scale land cover mapping and the relevance of ancillary data for the classification success in order to assess and to quantify the importance of these components in image classification. Specifically tested are the performance of maximum likelihood classification (MLC), artificial neural networks (ANN) and discriminant analysis (DA) based on Landsat7 ETM+ spectral data in combination with topographic measures and NDVI. ANN produced high accuracies of more than 75% also with limited input information, while MLC and DA produced comparable results only by incorporating ancillary data into the classification process. The superiority of ANN classification was less pronounced on the level of the single land cover classes. The use of ancillary data generally increased classification accuracy and showed a similar potential for increasing classification accuracy than the selection of the classifier. Therefore, a stronger focus on the development of appropriate and optimised sets of input variables is suggested. Also the definition and selection of land cover classes has shown to be crucial and not to be simply adaptable from existing land cover class schemes. A stronger research focus towards discriminating land cover classes by their typical spectral, topographic or seasonal properties is therefore suggested to advance image classification.

Heinl, M.; Walde, J.; Tappeiner, G.; Tappeiner, U.

2009-12-01

29

Global Auroral Energy Deposition Derived from Polar UVI Images  

NASA Technical Reports Server (NTRS)

Quantitative measurement of the transfer of energy and momentum to the ionosphere from the solar wind is one of the main objectives of the ISTP program. Global measurement of auroral energy deposition derived from observations of the longer wavelength LBH band emissions made by the Ultraviolet Imager on the Polar spacecraft is one of the key elements in this satellite and ground-based instrument campaign. These "measurements" are inferred by combining information from consecutive images using different filters and have a time resolution on the average of three minutes and are made continuously over a 5 to 8 hour period during each 18 hour orbit of the Polar spacecraft. The energy deposition in the ionosphere from auroral electron precipitation augments are due to Joule heating associated with field aligned currents. Assuming conjugacy of energy deposition between the two hemispheres the total energy input to the ionosphere through electron precipitation can be determined at high time resolution. Previously, precipitating particle measurements along the tracks of low altitude satellites provided only local measurements and the global energy precipitation could be inferred through models but not directly measured. We use the UVI images for the entire month of January 1997 to estimate the global energy deposition at high time resolution. We also sort the energy deposition into sectors to find possible trends, for example, on the dayside and nightside, or the dawn and dusk sides.

Fillingim, M. O.; Brittnacher, M. J.; Elsen, R.; Parks, G. K.; Spann, J. F., Jr.; Germany, G. A.

1997-01-01

30

Estimation of Enterococci Input from Bathers and Animals on A Recreational Beach Using Camera Images  

PubMed Central

Enterococci, are used nationwide as a water quality indicator of marine recreational beaches. Prior research has demonstrated that enterococci inputs to the study beach site (located in Miami, FL) are dominated by non-point sources (including humans and animals). We have estimated their respective source functions by developing a counting methodology for individuals to better understand their non-point source load impacts. The method utilizes camera images of the beach taken at regular time intervals to determine the number of people and animal visitors. The developed method translates raw image counts for weekdays and weekend days into daily and monthly visitation rates. Enterococci source functions were computed from the observed number of unique individuals for average days of each month of the year, and from average load contributions for humans and for animals. Results indicate that dogs represent the larger source of enterococci relative to humans and birds.

D, Wang John; M, Solo-Gabriele Helena; M, Abdelzaher Amir; E, Fleming Lora

2010-01-01

31

Historical changes in terrestrially derived organic carbon inputs to Louisiana continental margin sediments over the past 150 years  

Microsoft Academic Search

Major rivers (and associated deltaic environments) provide the dominant pathway for the input of terrestrial-derived organic carbon in sediments (TOCT) to the ocean. Natural watershed processes and land-use changes are important in dictating the amount and character of carbon being buried on continental margins. Seven core sites were occupied on the Louisiana continental margin aboard the R\\/V Pelican in July

Troy P. Sampere; Thomas S. Bianchi; Mead A. Allison

2011-01-01

32

Glutamate Synaptic Inputs to Ventral Tegmental Area Neurons in the Rat Derive Primarily from Subcortical Sources  

PubMed Central

Dopamine and GABA neurons in the ventral tegmental area project to the nucleus accumbens and prefrontal cortex and modulate locomotor and reward behaviors as well as cognitive and affective processes. Both midbrain cell types receive synapses from glutamate afferents that provide an essential control of behaviorally-linked activity patterns, although the sources of glutamate inputs have not yet been completely characterized. We used antibodies against the vesicular glutamate transporters VGlut1 and VGlut2 to investigate the morphology and synaptic organization of axons containing these proteins as putative markers of glutamate afferents from cortical versus subcortical sites, respectively. We also characterized the ventral tegmental area cell populations receiving VGlut1+ or VGlut2+ synapses according to their transmitter phenotype (dopamine or GABA) and major projection target (nucleus accumbens or prefrontal cortex). By light and electron microscopic examination, VGlut2+ as opposed to VGlut1+ axon terminals were more numerous, had a larger average size, synapsed more proximally, and were more likely to form convergent synapses onto the same target. Both axon types formed predominantly asymmetric synapses, although VGlut2+ terminals more often formed synapses with symmetric morphology. No absolute selectivity was observed for VGlut1+ or VGlut2+ axons to target any particular cell population. However, the synapses onto mesoaccumbens neurons more often involved VGlut2+ terminals, whereas mesoprefrontal neurons received relatively equal synaptic inputs from VGlut1+ and VGlut2+ profiles. The distinct morphological features of VGlut1 and VGlut2 positive axons suggest that glutamate inputs from presumed cortical and subcortical sources, respectively, differ in the nature and intensity of their physiological actions on midbrain neurons. More specifically, our findings imply that subcortical glutamate inputs to the ventral tegmental area expressing VGlut2 predominate over cortical sources of excitation expressing VGlut1 and are more likely to drive the behaviorally-linked bursts in dopamine cells that signal future expectancy or attentional shifting.

Omelchenko, Natalia; Sesack, Susan R.

2007-01-01

33

Derivation of input function from FDG-PET studies in small hearts  

Microsoft Academic Search

The extraction of pure arterial time-activity curves (TACs) from dynamic PET images of a small animal heart using factor analysis of dynamic structures (FADS) was found to be unsuccessful due to the small size of the cardiac chamber that causes extensive mixture of TACs of different structures. In this study, we used digital phantoms of the left ventricle (LV cavity

Hsiao-Ming Wu; Sung-Cheng Huang; V. Allada

1996-01-01

34

Multi-modal pharmacokinetic modelling for DCE-MRI: using diffusion weighted imaging to constrain the local arterial input function  

NASA Astrophysics Data System (ADS)

The routine acquisition of multi-modal magnetic resonance imaging data in oncology yields the possibility of combined model fitting of traditionally separate models of tissue structure and function. In this work we hypothesise that diffusion weighted imaging data may help constrain the fitting of pharmacokinetic models to dynamic contrast enhanced (DCE) MRI data. Parameters related to tissue perfusion in the intra-voxel incoherent motion (IVIM) modelling of diffusion weighted MRI provide local information on how tissue is likely to perfuse that can be utilised to guide DCE modelling via local modification of the arterial input function (AIF). In this study we investigate, based on multi-parametric head and neck MRI of 8 subjects (4 with head and neck tumours), the benefit of incorporating parameters derived from the IVIM model within the DCE modelling procedure. Although we find the benefit of this procedure to be marginal on the data used in this work, it is conceivable that a technique of this type will be of greater use in a different application.

Hamy, Valentin; Modat, Marc; Shipley, Rebecca; Dikaios, Nikos; Cleary, Jon; Punwani, Shonit; Ourselin, Sebastien; Atkinson, David; Melbourne, Andrew

2014-03-01

35

IMPROVED DERIVATION OF INPUT FUNCTION IN DYNAMIC MOUSE [18F]FDG PET USING BLADDER RADIOACTIVITY KINETICS  

PubMed Central

Purpose Accurate determination of the plasma input function (IF) is essential for absolute quantification of physiological parameters in positron emission tomography (PET). However, it requires an invasive and tedious procedure of arterial blood sampling that is challenging in mice because of the limited blood volume. In this study, a hybrid modeling approach is proposed to estimate the plasma IF of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) in mice using accumulated radioactivity in urinary bladder together with a single late-time blood sample measurement. Methods Dynamic PET scans were performed on nine isoflurane-anesthetized male C57BL/6 mice after a bolus injection of [18F]FDG at the lateral caudal vein. During a 60- or 90-min scan, serial blood samples were taken from the femoral artery. Image data were reconstructed using filtered backprojection with CT-based attenuation correction. Total accumulated radioactivity in the urinary bladder was fitted to a renal compartmental model with the last blood sample and a 1-exponential function that described the [18F]FDG clearance in blood. Multiple late-time blood sample estimates were calculated by the blood [18F]FDG clearance equation. A sum of 4-exponentials was assumed for the plasma IF that served as a forcing function to all tissues. The estimated plasma IF was obtained by simultaneously fitting the [18F]FDG model to the time-activity curves (TACs) of liver and muscle and the forcing function to early (0–1 min) left-ventricle data (corrected for delay, dispersion, partial-volume effects and erythrocytes uptake) and the late-time blood estimates. Using only the blood sample acquired at the end of the study to estimate the IF and the use of liver TAC as an alternative IF were also investigated. Results The area under the plasma TACs calculated for all studies using the hybrid approach was not significantly different from that using all blood samples. [18F]FDG uptake constants in brain, myocardium, skeletal muscle and liver computed by the Patlak analysis using estimated and measured plasma TACs were in excellent agreement (slope ~ 1; R2 > 0.938). The IF estimated using only the last blood sample acquired at the end of the study and the use of liver TAC as plasma IF provided less reliable results. Conclusions The estimated plasma IFs obtained with the hybrid model agreed well with those derived from arterial blood sampling. Importantly, the proposed method obviates the need of arterial catheterization, making it possible to perform repeated dynamic [18F]FDG PET studies on the same animal. Liver TAC is unsuitable as an input function for absolute quantification of [18F]FDG PET data.

Wong, Koon-Pong; Zhang, Xiaoli; Huang, Sung-Cheng

2013-01-01

36

Groundwater-derived nutrient inputs to the Upper Gulf of Thailand  

NASA Astrophysics Data System (ADS)

We report here the first direct measurements of nutrient fluxes via groundwater discharge into the Upper Gulf of Thailand. Nutrient and standard oceanographic surveys were conducted during the wet and dry seasons along the Chao Phraya River, Estuary and out into the Upper Gulf of Thailand. Additional measurements in selected near-shore regions of the Gulf included manual and automatic seepage meter deployments, as well as nutrient evaluations of seepage and coastal waters. The river transects characterized the distribution of biogeochemical parameters in this highly contaminated urban environment. Seepage flux measurements together with nutrient analyses of seepage fluids were used to estimate nutrient fluxes via groundwater pathways for comparison to riverine fluxes. Our findings show that disseminated seepage of nutrient-rich mostly saline groundwater into the Upper Gulf of Thailand is significant. Estimated fluxes of dissolved inorganic nitrogen (DIN) supplied via groundwater discharge were 40-50% of that delivered by the Chao Phraya River, inorganic phosphate was 60-70%, and silica was 15-40%. Dissolved organic nitrogen (DON) and phosphorus (DOP) groundwater fluxes were also high at 30-40% and 30-130% of the river inputs, respectively. These observations are especially impressive since the comparison is being made to the river that is the largest source of fresh water into the Gulf of Thailand and flows directly through the megacity of Bangkok with high nutrient loadings from industrial and domestic sources.

Burnett, William C.; Wattayakorn, Gullaya; Taniguchi, Makoto; Dulaiova, Henrieta; Sojisuporn, Pramot; Rungsupa, Sompop; Ishitobi, Tomotoshi

2007-01-01

37

Combustion-derived substances in deep basins of Puget Sound: historical inputs from fossil fuel and biomass combustion.  

PubMed

Reconstructions of 250 years historical inputs of two distinct types of black carbon (soot/graphitic black carbon (GBC) and char-BC) were conducted on sediment cores from two basins of the Puget Sound, WA. Signatures of polycyclic aromatic hydrocarbons (PAHs) were also used to support the historical reconstructions of BC to this system. Down-core maxima in GBC and combustion-derived PAHs occurred in the 1940s in the cores from the Puget Sound Main Basin, whereas in Hood Canal such peak was observed in the 1970s, showing basin-specific differences in inputs of combustion byproducts. This system showed relatively higher inputs from softwood combustion than the northeastern U.S. The historical variations in char-BC concentrations were consistent with shifts in climate indices, suggesting an influence of climate oscillations on wildfire events. Environmental loading of combustion byproducts thus appears as a complex function of urbanization, fuel usage, combustion technology, environmental policies, and climate conditions. PMID:21236534

Kuo, Li-Jung; Louchouarn, Patrick; Herbert, Bruce E; Brandenberger, Jill M; Wade, Terry L; Crecelius, Eric

2011-04-01

38

Boolean Derivatives With Application to Edge Detection for Imaging Systems  

Microsoft Academic Search

This paper introduces a new concept of Boolean derivatives as a fusion of partial derivatives of Boolean functions (PDBFs). Three efficient algorithms for the calculation of PDBFs are presented. It is shown that Boolean function derivatives are useful for the application of identifying the location of edge pixels in binary images. The same concept is extended to the development of

Sos S. Agaian; Karen A. Panetta; Shahan C. Nercessian; Ethan E. Danahy

2010-01-01

39

An improved temperature index model for alpine glaciers using derived degree-day factors from climatic inputs  

NASA Astrophysics Data System (ADS)

Glacier melt rates are strongly affected by minor perturbations in climatic systems. Quantifying changes in glacier melt rates is therefore important, particularly in areas where melt-water contributes to hydroelectric power generation, irrigation, or flood risks. Several methods currently exist for modeling glacier melt rates, but one widely used method is temperature index modeling, also called positive degree-day modeling. This model is often applied due to its simplicity and small number of input variables, but it still depends on an empirically-measured scaling constant (the degree-day factor). These degree-day factors can vary by a factor of five from one glacier to the next, complicating the applicability of the approach to new regions, or to different time periods. Previous work suggests the degree-day factor may be a function of the surface albedo, solar radiation, and near-surface air temperature. Thus, it is possible the degree-day factor itself is predictable. In this study we present a method to derive these melt factors directly from easily obtained climatic variables, thus allowing for the ready application of temperature index modeling to a much wider suite of glaciers with greater accuracy. We used a full energy-balance model to calculate possible degree-day factors over the full range of climate conditions commonly encountered with alpine glaciers. We then constructed a statistical emulator (a linear model which considers numerous interactions and polynomial effects) using select climate variables (insolation, positive degree-days, and albedo) as inputs. The statistical model is tuned using the energy-balance output as training data. The model skill will be tested against a suite of empirically-derived degree-day factors. These results would allow for the application of more accurate glacier melt models with quantified uncertainties to under-sampled glacial regions and paleoclimate reconstructions.

Keeler, D. G.; Havens, A. P.; Rupper, S.; Christensen, W. F.

2013-12-01

40

Diphenyl Ether Derivatives and Their Use for Imaging Serotonin Transporters.  

National Technical Information Service (NTIS)

This invention relates to diphenyl ether derivatives and their use in imaging of Serotonin Transporters (SERTS). The present invention also provides diagnostic compositions comprising the compounds of the present invention, and a pharmaceutically acceptab...

H. F. Kung

2005-01-01

41

Boolean derivatives with application to edge detection for imaging systems.  

PubMed

This paper introduces a new concept of Boolean derivatives as a fusion of partial derivatives of Boolean functions (PDBFs). Three efficient algorithms for the calculation of PDBFs are presented. It is shown that Boolean function derivatives are useful for the application of identifying the location of edge pixels in binary images. The same concept is extended to the development of a new edge detection algorithm for grayscale images, which yields competitive results, compared with those of traditional methods. Furthermore, a new measure is introduced to automatically determine the parameter values used in the thresholding portion of the binarization procedure. Through computer simulations, demonstrations of Boolean derivatives and the effectiveness of the presented edge detection algorithm, compared with traditional edge detection algorithms, are shown using several synthetic and natural test images. In order to make quantitative comparisons, two quantitative measures are used: one based on the recovery of the original image from the output edge map and the Pratt's figure of merit. PMID:19884097

Agaian, Sos S; Panetta, Karen A; Nercessian, Shahan C; Danahy, Ethan E

2010-04-01

42

Thermal imaging for input to terrestrial and planetary thermal models (Invited)  

NASA Astrophysics Data System (ADS)

Multispectral imaging of emitted thermal radiation is used to estimate surface composition, especially of silicate minerals, but the most common use is to estimate surface temperature T. Thermal modeling requires accurate estimation of T, which for many terrestrial and nearly all planetary studies requires measuring radiance L remotely. The key difficulty is that thermal imaging is underdetermined, with 3 atmospheric parameters and n+1 surface parameters where n is the number of channels (i, j...), even if adjacency effects and anisothermal pixels are overlooked. The n unknowns are emissivities ? (i), and if T is to be estimated something about the ? spectrum must generally be known or assumed. Many different algorithms have been devised. If n=1, ? is assumed from laboratory data; if n=2, T for water is proportional to L(i) and L(j)-L(i) (split-window technique), empirically calibrated. One of the benefits of multispectral imaging is that ?(i) can be estimated pixel by pixel, such that T can be recovered with more confidence. Multispectral and hyperspectral data are commonly handled by assuming the maximum value of ?. Under some conditions, two-time imaging can be used assuming that ?(i) is unchanging. Generally, terrestrial atmospheric corrections, instrumental calibration and ? assumptions contribute roughly equally to T inaccuracy of 1-2 K for high spatial resolution data, although for low resolution, restricted atmospheric conditions, and known surface composition this figure can be improved. Peak L occurs at increasing wavenumber as T rises. Thus, T recovery for active volcanoes makes use of midwave (2000-3300 cm-1) or shortwave (3300-10,000 cm-1) rather than longwave thermal infrared (700-1250 cm-1). One complexity is atmospheric variability near active vents; another is the possibility that ? may change as lava cools and the crystallinity of the skin changes (Abtahi et al., 2002). At the other extreme Mars and the icy satellites have low T and therefore lower SNR than warmer targets. This especially is true at night, for example on Mars. Thermal inertia, a measure of the resistance of a surface to changing its T as energy is added or subtracted to it, can be estimated from day-night temperature differences. It can in principle be used to learn something about the porosity, rock/soil ratios, the presence of thin veneers of sand, or other non-compositional characteristics of a surface. Quantitative measures of T, ? and thermal inertia are needed for thermal modeling. However, calculating thermal inertia requires accounting for topography and albedo and is more challenging than just estimating T, and therefore on both Earth and Mars approximations to it are commonly used photointerpretively, just as images of T images and even derived ? are sometimes used photointerpretively also.

Gillespie, A. R.

2013-12-01

43

A Hybrid Clustering Method for ROI Delineation in Small Animal Dynamic PET Images: Application to the Automatic Estimation of FDG Input Functions  

PubMed Central

Tracer kinetic modeling with dynamic Positron Emission Tomography (PET) requires a plasma time-activity curve (PTAC) as an input function. Several image-derived input function (IDIF) methods that rely on drawing the region-of-interest (ROI) in large vascular structures have been proposed to overcome the problems caused by the invasive approach to obtaining the PTAC, especially for small animal studies. However, the manual placement of ROIs for estimating IDIF is subjective and labor-intensive, making it an undesirable and unreliable process. In this paper, we propose a novel hybrid clustering method (HCM) that objectively delineates ROIs in dynamic PET images for the estimation of IDIFs, and demonstrate its application to the mouse PET studies acquired with [18F]Fluoro-2-deoxy-2-D-glucose (FDG). We begin our HCM using K-means clustering for background removal. We then model the time-activity curves using polynomial regression mixture models in curve clustering for heart structure detection. The hierarchical clustering is finally applied for ROI refinements. The HCM achieved accurate ROI delineation in both computer simulations and experimental mouse studies. In the mouse studies the predicted IDIF had a high correlation with the gold standard, the PTAC derived from the invasive blood samples. The results indicate that the proposed HCM has a great potential in ROI delineation for automatic estimation of IDIF in dynamic FDG-PET studies.

Zheng, Xiujuan; Tian, Guangjian; Huang, Sung-Cheng; Feng, Dagan

2011-01-01

44

Direct Characterization of Arterial Input Functions by Fluorescence Imaging of Exposed Carotid Artery to Facilitate Kinetic Analysis  

PubMed Central

Purpose With the goal of facilitating tracer kinetic analysis in small-animal planar fluorescence imaging, an experimental method for characterizing tracer arterial input functions is presented. The proposed method involves exposing the common carotid arteries by surgical dissection, which can then be imaged directly during tracer injection and clearance. Procedures Arterial concentration curves of IRDye-700DX-carboxylate, IRDye-800CW-EGF, and IRDye-800CW conjugated to anti-EGFR Affibody are recovered from athymic female mice (n=12) by directly imaging exposed vessels. Images were acquired with two imaging protocols: a slow-kinetics approach (temporal resolution=45 s) to recover the arterial curves from two tracers simultaneously, and a fast-kinetics approach (temporal resolution=500 ms) to characterize the first-pass peak of a single tracer. Arterial input functions obtained by the carotid imaging technique, as well as plasma curves measured by blood sampling were fit with a biexponential pharmacokinetic model. Results Pharmacological fast- and slow-phase rate constants recovered with the proposed method were 0.37±0.26 and 0.007±0.001 min?1, respectively, for the IRDye700DX-C. For the IRDye800CW-EGF, the rate constants were 0.11±0.13 and 0.003±0.002 min?1. These rate constants did not differ significantly from those calculated previously by blood sampling, as determined by an F test; however, the between-subject variability was four times lower for arterial curves recovered using the proposed technique, compared with blood sampling. Conclusions The proposed technique enables the direct characterization of arterial input functions for kinetic analysis. As this method requires no additional instrumentation, it is immediately deployable in commercially available planar fluorescence imaging systems.

Elliott, Jonathan T.; Tichauer, Kenneth M.; Samkoe, Kimberley S.; Gunn, Jason R.; Sexton, Kristian J.; Pogue, Brian W.

2014-01-01

45

The Rate of Weathering-Derived Calcium Input to a Base-Poor Forest Ecosystem in the Northeastern USA  

NASA Astrophysics Data System (ADS)

Over the past 50 years,acid deposition in the northeastern USA has leached calcium and other base cations (K, Na, and Mg) from the soil exchange complex, creating a nutrient-poor environment for trees. In order to quantify losses from the soil exchange pool and estimate ecosystem recovery from acid deposition, inputs from atmospheric deposition and mineral weathering must be known. Atmospheric deposition can be measured directly, but weathering inputs are difficult to distinguish from cation exchange pool depletion in stream fluxes. The objectives of this study were to determine the variability of long-term weathering rates across a small watershed at Hubbard Brook Experimental Forest (HBEF), NH, and to compare these rates to the current flux of cations from the watershed. The HBEF is a northern hardwood forest last logged in the early 1900s; at higher elevations, conifers are dominant. Soils have developed on relatively homogeneous, glacial till deposited about 14,000 years ago and derived predominantly from granodiorite and pelitic schist. Soils were sampled by horizon from 45 soil pits within a 12-hectare watershed. Long-term weathering rates were calculated as the loss of elements from soils relative to the parent material using Ti as an immobile element. The average long-term chemical weathering rate in the watershed (40 meq m-2 yr-1) is similar to rates in other 10 to 15 ka old soils developed on granitic till in temperate climates. The soil parent material is chemically homogeneous, yet the weathering rates range from 21 to 65 meq m-2 yr-1 across the watershed, generally increasing with elevation due to changes in vegetation, soil water flow paths, and depth to impermeable bedrock. Feldspar weathering rates are greater at higher elevations at HBEF. Plagioclase weathering accounts for a significant amount (56-84%) of the calcium lost from the soils over the last 14,000 years, while the dissolution of apatite accounts for 15 to 32%. The present-day loss of base cations from the watershed greatly exceeds the long-term weathering rate providing additional support that the pool of exchangeable base cations in the soil continues to be diminished.

Nezat, C. A.; Blum, J. D.; Johnson, C. E.

2003-12-01

46

Multiple-input multiple-output (MIMO) radar and imaging: degrees of freedom and resolution  

Microsoft Academic Search

In this paper, radar is discussed in the context of a multiple-input multiple-output (MIMO) system model. A comparison is made between MIMO wireless communication and MIMO radar. Examples are given showing that many traditional radar approaches can be interpreted within a MIMO context. Furthermore, exploiting this MIMO perspective, useful extensions to traditional radar can be constructed. Performance advantages in terms

D. W. Bliss; K. W. Forsythe

2003-01-01

47

Wh-Questions in Child L2 French: Derivational Complexity and Its Interactions with L1 Properties, Length of Exposure, Age of Exposure, and the Input  

ERIC Educational Resources Information Center

This study investigates how derivational complexity interacts with first language (L1) properties, second language (L2) input, age of first exposure to the target language, and length of exposure in child L2 acquisition. We compared elicited production of "wh"-questions in French in two groups of 15 participants each, one with L1 English…

Prévost, Philippe; Strik, Nelleke; Tuller, Laurie

2014-01-01

48

Interpretation of caesium-137 profiles in lacustrine and other sediments: the role of catchment-derived inputs  

Microsoft Academic Search

The caesium-137 profiles obtained in many investigations which have attempted to use caesium-137 measurements as a means of assessing the rate of accumulation of recent lake sediments, have not conformed to the classic shape expected from the record of fallout input. Such deviations have been accounted for in terms of post-depositional mobility of the caesium-137 input (e.g. bioturbation) and delayed

D. E. Walling; He Qingping

1992-01-01

49

Genetic dissection of retinal inputs to brainstem nuclei controlling image stabilization.  

PubMed

When the head rotates, the image of the visual world slips across the retina. A dedicated set of retinal ganglion cells (RGCs) and brainstem visual nuclei termed the "accessory optic system" (AOS) generate slip-compensating eye movements that stabilize visual images on the retina and improve visual performance. Which types of RGCs project to each of the various AOS nuclei remain unresolved. Here we report a new transgenic mouse line, Hoxd10-GFP, in which the RGCs projecting to all the AOS nuclei are fluorescently labeled. Electrophysiological recordings of Hoxd10-GFP RGCs revealed that they include all three subtypes of On direction-selective RGCs (On-DSGCs), responding to upward, downward, or forward motion. Hoxd10-GFP RGCs also include one subtype of On-Off DSGCs tuned for forward motion. Retrograde circuit mapping with modified rabies viruses revealed that the On-DSGCs project to the brainstem centers involved in both horizontal and vertical retinal slip compensation. In contrast, the On-Off DSGCs labeled in Hoxd10-GFP mice projected to AOS nuclei controlling horizontal but not vertical image stabilization. Moreover, the forward tuned On-Off DSGCs appear physiologically and molecularly distinct from all previously genetically identified On-Off DSGCs. These data begin to clarify the cell types and circuits underlying image stabilization during self-motion, and they support an unexpected diversity of DSGC subtypes. PMID:24198370

Dhande, Onkar S; Estevez, Maureen E; Quattrochi, Lauren E; El-Danaf, Rana N; Nguyen, Phong L; Berson, David M; Huberman, Andrew D

2013-11-01

50

Genetic Dissection of Retinal Inputs to Brainstem Nuclei Controlling Image Stabilization  

PubMed Central

When the head rotates, the image of the visual world slips across the retina. A dedicated set of retinal ganglion cells (RGCs) and brainstem visual nuclei termed the “accessory optic system” (AOS) generate slip-compensating eye movements that stabilize visual images on the retina and improve visual performance. Which types of RGCs project to each of the various AOS nuclei remain unresolved. Here we report a new transgenic mouse line, Hoxd10–GFP, in which the RGCs projecting to all the AOS nuclei are fluorescently labeled. Electrophysiological recordings of Hoxd10–GFP RGCs revealed that they include all three subtypes of On direction-selective RGCs (On–DSGCs), responding to upward, downward, or forward motion. Hoxd10–GFP RGCs also include one subtype of On–Off DSGCs tuned for forward motion. Retrograde circuit mapping with modified rabies viruses revealed that the On–DSGCs project to the brainstem centers involved in both horizontal and vertical retinal slip compensation. In contrast, the On–Off DSGCs labeled in Hoxd10–GFP mice projected to AOS nuclei controlling horizontal but not vertical image stabilization. Moreover, the forward tuned On–Off DSGCs appear physiologically and molecularly distinct from all previously genetically identified On–Off DSGCs. These data begin to clarify the cell types and circuits underlying image stabilization during self-motion, and they support an unexpected diversity of DSGC subtypes.

Dhande, Onkar S.; Estevez, Maureen E.; Quattrochi, Lauren E.; El-Danaf, Rana N.; Nguyen, Phong L.

2013-01-01

51

Derivate  

NSDL National Science Digital Library

In this activity, students input functions in order to calculate the derivative and tangent line of that function. This activity allows students to explore tangent lines of various functions. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2010-01-01

52

Design criteria for a multiple input land use system. [digital image processing techniques  

NASA Technical Reports Server (NTRS)

A design is presented that proposes the use of digital image processing techniques to interface existing geocoded data sets and information management systems with thematic maps and remote sensed imagery. The basic premise is that geocoded data sets can be referenced to a raster scan that is equivalent to a grid cell data set, and that images taken of thematic maps or from remote sensing platforms can be converted to a raster scan. A major advantage of the raster format is that x, y coordinates are implicitly recognized by their position in the scan, and z values can be treated as Boolean layers in a three-dimensional data space. Such a system permits the rapid incorporation of data sets, rapid comparison of data sets, and adaptation to variable scales by resampling the raster scans.

Billingsley, F. C.; Bryant, N. A.

1975-01-01

53

Short-Range Ultra-Wideband Imaging with Multiple-Input Multiple-Output Arrays  

Microsoft Academic Search

Compact, cost-efficient and high-resolution imaging sensors are especially desirable in the field of short-range observation and surveillance. Such sensors are of great value in fields of security, rescue and medical applications. Systems can be formed for various practical purposes, such as detecting concealed weapons in public places, locating people inside buildings or beneath rubbles during emergency rescue, detecting landmine with

X. Zhuge

2010-01-01

54

Functional Imaging of the Human Brainstem during Somatosensory Input and Autonomic Output  

PubMed Central

Over the past half a century, many investigations in experimental animal have explored the functional roles of specific regions in the brainstem. Despite the accumulation of a considerable body of knowledge in, primarily, anesthetized preparations, relatively few studies have explored brainstem function in awake humans. It is important that human brainstem function is explored given that many neurological conditions, from obstructive sleep apnea, chronic pain, and hypertension, likely involve significant changes in the processing of information within the brainstem. Recent advances in the collection and processing of magnetic resonance images have resulted in the possibility of exploring brainstem activity changes in awake healthy individuals and in those with various clinical conditions. We and others have begun to explore changes in brainstem activity in humans during a number of challenges, including cutaneous and muscle pain, as well as during maneuvers that evoke increases in sympathetic nerve activity. More recently we have successfully recorded sympathetic nerve activity concurrently with functional magnetic resonance imaging of the brainstem, which will allow us, for the first time to explore brainstem sites directly responsible for conditions such as hypertension. Since many pathophysiological conditions no doubt involve changes in brainstem function and structure, defining these changes will likely result in a greater ability to develop more effective treatment regimens.

Henderson, Luke A.; Macefield, Vaughan G.

2013-01-01

55

Propagation of uncertainty analysis of CO2 transfer velocities derived from the COARE gas transfer model using satellite inputs  

NASA Astrophysics Data System (ADS)

propagation of uncertainty method is developed to describe gas transfer uncertainties for carbon dioxide (CO2) using the National Oceanic and Atmospheric Administration-Coupled Ocean Atmosphere Response Experiment (NOAA-COARE) gas transfer model (COAREG). The uncertainty model assesses the impact uncertainties in satellite inputs to COAREG have on the resulting carbon dioxide gas transfer velocities. The model impact of 10 m temperature, 10 m specific humidity, 10 m wind speed, sea surface temperature, longwave and shortwave downward surface flux are investigated. Nine years of gas transfer velocities and their uncertainties were constructed and analyzed. The climatological mean transfer velocities were found to have standard errors of less than 15%. Spatial and temporal variations of the uncertainties from these inputs are presented and the percentage variance explained for each input was dominated by uncertainties in wind speed. Uncertainty due to the covariance between air temperature and wind speed and the uncertainties in the 10 m air temperature at low wind speed conditions were found to be significant. Additionally, the likelihood air temperature uncertainties affect the gas transfer uncertainty is greatest in regions where air temperature exceeds sea surface temperature. Buoyancy-driven transfer in COAREG increases gas transfer velocities uncertainties under these conditions. These conditions most typically occur in regions along the equatorial cold tongue region east of South America and in the North Pacific and North Atlantic.

Jackson, Darren L.; Wick, Gary A.

2014-03-01

56

Importance of budgets for estimating the input of groundwater-derived nutrients to an eutrophic tidal river and estuary  

NASA Astrophysics Data System (ADS)

Groundwater is often overlooked as a source of nutrients to estuaries and most previous groundwater-surface water exchange studies did not consider the input of dissolved organic nutrients. Here, we hypothesize that groundwater is contributing to high dissolved inorganic and organic nutrient concentrations in an eutrophic subtropical tidal river and estuary (Caboolture River, Queensland, Australia). Several spatial radon (222Rn, a natural groundwater tracer) surveys indicated that the majority of groundwater discharge occurred in the tidal river just upstream of the estuary, and that the radon hotspot did not necessarily coincide with the nutrient hotspot. A radon mass balance revealed that groundwater discharge into the tidal river was equivalent to about 50% of the gauged river flow in February 2012. Groundwater discharge apparently contributed 85% of ammonium and 35% of phosphate entering the estuary. In spite of significant correlations between radon and nitrate and dissolved organic nitrogen (DON) during spatial surveys, groundwater could account for only 7% of nitrate and 9% of DON inputs due to low groundwater concentrations and other sources (i.e., apparently a sewage treatment plant for nitrate and floodplain tributaries for DON). Because total dissolved nitrogen (TDN) was dominated by DON (69%) and nitrate (23%), the groundwater ammonium inputs were a minor source to the TDN pool within the tidal river and estuary. This study demonstrated that correlations between a groundwater tracer and nutrient concentrations do not necessarily illustrate causation. To assess how groundwater drives nutrient dynamics in estuaries, it may be important to include the tidal river (not only the estuarine salinity gradient) in field investigations, consider DON (not only ammonium and nitrate), and perform detailed budgets that include minor tributaries.

Makings, Uriah; Santos, Isaac R.; Maher, Damien T.; Golsby-Smith, Lindsay; Eyre, Bradley D.

2014-04-01

57

Extraction of a series of novel damage sensitive features derived from the continuous wavelet transform of input and output acceleration measurements  

NASA Astrophysics Data System (ADS)

This paper proposes a series of novel Damage Sensitive Features for earthquake damage estimation. The features take into account input (ground motion) and output acceleration (structure response) measurements. The Continuous Wavelet Transform is applied to both acceleration signals in order to obtain both time domain and frequency domain resolution. An algorithm that has been proposed for Maximum Entropy Deconvolution is applied to the Continuous Wavelet Transforms in order to obtain a matrix that relates the output wavelet coefficients to the input ones. The Damage Sensitive Features are then derived through statistical processing of the resulting matrix. This algorithm has been applied on data acquired from shake table tests where the structures were subjected to progressive damage. The proposed features are compared to response quantities that are indicative of damage (such as the hysteretic energy dissipated) and show high correlation with the extent of damage. The data utilized has not been pre-processed, illustrating the robustness of the algorithm against sensor noise. The proposed algorithm has several advantages: Minimal input and knowledge of the structure is required. More information on the structure's state is extracted through use of both the input and output signals than when only output signal is considered. Only two acceleration measurements are required to obtain a damage forecast utilizing primarily the strong motion recordings, resulting in easier sensor deployment. The use of strong motion recordings allows for information delivery immediately after an earthquake without additional data collection.

Balafas, Konstantinos; Kiremidjian, Anne S.

2014-03-01

58

High resolution fire danger modeling : integration of quantitative precipitation amount estimates derived from weather radars as an input of FWI  

NASA Astrophysics Data System (ADS)

Fire meteo indices provide efficient guidance tools for the prevention, early warning and surveillance of forest fires. The indices are based on meteorological input data. The underlying approach is to exploit meteorological information as fully as possible to model the soil water content, biomass condition and fire danger. Fire meteorological danger is estimated by Météo-France at national level through the use of Fire Weather Index. The fire index services developed within the PREVIEW project (2005-2008) offer for the first time very high resolution mapping of forest fire risk. The high resolution FWI has been implemented in France complementary to the existing EFFIS operated by the Joint Research Center. A new method (ANTILOPE method) of combining precipitation data originating from different sources like rain gauges and weather radar measurements has been applied in the new service. Some of the advantages of this new service are: · Improved detection of local features of fire risk · More accurate analysis of meteorological input data used in forest fire index models providing added value for forest fire risk forecasts · Use of radar precipitation data "as is” utilizing the higher resolution, i.e. avoiding averaging operations The improved accuracy and spatial resolution of the indices provide a powerful early warning tool for national and regional civil protection and fire fighting authorities to alert and initiate forest fire fighting actions and measures.

Cloppet, E.; Regimbeau, M.

2009-09-01

59

The Atlases of Vesta derived from Dawn Framing Camera images  

NASA Astrophysics Data System (ADS)

The Dawn Framing Camera acquired during its two HAMO (High Altitude Mapping Orbit) phases in 2011 and 2012 about 6,000 clear filter images with a resolution of about 60 m/pixel. We combined these images in a global ortho-rectified mosaic of Vesta (60 m/pixel resolution). Only very small areas near the northern pole were still in darkness and are missing in the mosaic. The Dawn Framing Camera also acquired about 10,000 high-resolution clear filter images (about 20 m/pixel) of Vesta during its Low Altitude Mapping Orbit (LAMO). Unfortunately, the northern part of Vesta was still in darkness during this phase, good illumination (incidence angle < 70°) was only available for 66.8 % of the surface [1]. We used the LAMO images to calculate another global mosaic of Vesta, this time with 20 m/pixel resolution. Both global mosaics were used to produce atlases of Vesta: a HAMO atlas with 15 tiles at a scale of 1:500,000 and a LAMO atlas with 30 tiles at a scale between 1:200,000 and 1:225,180. The nomenclature used in these atlases is based on names and places historically associated with the Roman goddess Vesta, and is compliant with the rules of the IAU. 65 names for geological features were already approved by the IAU, 39 additional names are currently under review. Selected examples of both atlases will be shown in this presentation. Reference: [1]Roatsch, Th., etal., High-resolution Vesta Low Altitude Mapping Orbit Atlas derived from Dawn Framing Camera images. Planetary and Space Science (2013), http://dx.doi.org/10.1016/j.pss.2013.06.024i

Roatsch, T.; Kersten, E.; Matz, K.; Preusker, F.; Scholten, F.; Jaumann, R.; Raymond, C. A.; Russell, C. T.

2013-12-01

60

Inputs of glacially derived dissolved and colloidal iron to the coastal ocean and implications for primary productivity  

NASA Astrophysics Data System (ADS)

Glacial meltwaters draining shield bedrock under the Greenland Ice Sheet (GIS) contain <0.4 ?m "total dissolved" Fe (TDFe) with an average flow weighted concentration of ˜53 nM. The concentrations of <0.03 and 0.03-0.4 ?m Fe vary over the ablation period, with weighted means for each of these fractions being respectively 22.4 nM and 30.8 nM. These concentrations are lower estimates as an adjacent larger glacier (a more representative source of glacial meltwater) had higher dissolved Fe concentrations, and reactions of meltwaters with proglacial sediments could also enhance dissolved Fe concentrations. This source of TDFe is additional to the reactive (oxyhydr)oxide phases identified by Raiswell et al. (2006) that are also introduced to adjacent polar seas from glaciers. The Fe concentrations in the shield bedrock underlying the GIS are lower than those of other crustal rocks (4.0% cf. 6.2%), but we argue that these Fe concentrations are not limiting on the total dissolved Fe concentrations we measure. The biogeochemical weathering processes operating on the subglacial debris and suspended sediment in our catchment are likely to be similar to those in other glaciated catchments. Therefore the meltwater Fe concentrations reported here can be used to give a first estimate of global fluxes of meltwater dissolved Fe to coastal polar waters. A lower estimate of the global flux of TDFe from glacial meltwaters is ˜75 × 106 moles Fe/a. This glacial meltwater input of Fe to adjacent polar waters will be greatest around Greenland where there are highest annual meltwater discharges. However, the greatest impact of this source of glacial meltwater Fe is anticipated to be in Antarctic high nutrient low chlorophyll (HNLC) waters where phytoplankton productivity is typically limited by availability of Fe. For Antarctic waters the estimated meltwater Fe (TDFe) input is about 10% of that suggested to come from sea ice melting, but glacial inputs continue throughout the austral summer ablation period after sea ice melt is complete.

Statham, Peter J.; Skidmore, Mark; Tranter, Martyn

2008-09-01

61

Single subject image analysis using the complex general linear model--an application to functional magnetic resonance imaging with multiple inputs.  

PubMed

A linear time invariant model is applied to functional fMRI blood flow data. Based on traditional time series analysis, this model assumes that the fMRI stochastic output sequence can be determined by a constant plus a linear filter (hemodynamic response function) of several fixed deterministic inputs and an error term assumed stationary with zero mean. The input function consists of multiple exponential distributed (time delay between images) visual stimuli consisting of negative and erotic images. No a priori assumptions are made about the hemodynamic response function that, in essence, is calculated at each spatial position from the data. The sampling rate for the experiment is 400 ms in order to allow for filtering out higher frequencies associated with the cardiac rate. Since the statistical analysis is carried out in the Fourier domain, temporal correlation problems associated with inference in the time domain are avoided. This formal model easily lends itself to further development based on previously developed statistical techniques. PMID:16530880

Rio, Daniel E; Rawlings, Robert R; Woltz, Lawrence A; Salloum, Jasmin B; Hommer, Daniel W

2006-04-01

62

Comparison of a Range of Terrain Variables Derived From DEMs Based on Different Resolutions and Input Data  

NASA Astrophysics Data System (ADS)

It is a well-known fact that the grid cell size of a raster digital elevation model has significant effects on derived terrain variables such as slope, aspect, plan and profile curvature or the wetness index. This poster presents vital information for users of DEMs generated from 100 m regularly sampled, or similar, elevation points such as those available province-wide for Alberta, Canada. Findings are valid for flat to moderately sloped terrain present in the North American prairies and foothills regions and other locations with similar terrain. DEMs with grid cell sizes ranging from 100 to 5 m were interpolated from both 100 and 10 m regularly spaced elevation points using the ANUDEM interpolation method. Significant differences in a number of terrain variables derived from DEMs with different resolutions using cumulative distribution functions and a subsequent Kolmogorov-Smirnov test are revealed. Terrain variables based on 100 m regularly sampled elevation points (100 m DEM) are compared to a DEM based on 10 m regularly sampled elevation points which serves as a benchmark. Correlation analysis reveals that only elevation and slope have a strong positive relationship while all other terrain derivatives are not represented realistically. Relative root mean square errors quantify the quality of terrain derivatives. Major findings are summarised as follows: (a) All computed terrain variables tested (slope, aspect, plan and profile curvature, curvature and the wetness index) vary significantly with a change in grid cell size; (b) the higher the order of the derivative, the smaller the DEM resolution should be; (c) only elevation and slope show a high correlation between the 100 m DEM and the benchmark DEM; (d) the 100 m DEM can, therefore, only be used to show the general range and general spatial distribution of terrain variables, but fails - with the exception of slope - to represent spatially correctly the terrain variables at the associated scale.

Kienzle, S. W.

2002-12-01

63

The least-squares mixing models to generate fraction images derived from remote sensing multispectral data  

Microsoft Academic Search

Constrained-least-squares (CLS) and weighted-least-squares (WLS) mixing models for generating fraction images derived from remote sensing multispectral data are presented. An experiment considering three components within the pixels-eucalyptus, soil (understory), and shade-was performed. The generated fraction images for shade (shade image) derived from these two methods were compared by considering the performance and computer time. The derived shade images are related

Yosio Edemir Shimabukuro; James A. Smith

1991-01-01

64

Derivation of Population Distribution Using Remote Sensing and Statistical Data as an Input for Tsunami Risk Assessment  

NASA Astrophysics Data System (ADS)

Information about people distribution is a crucial component in disaster risk management. Every disaster such as flood, drought, tsunami, volcanic eruption, storm, earthquake etc. implies threats to people with respect to loss of live, injury, and suffer. The number of people affected during 1991 - 2005 is approximately 3.5 billion people (UN ESCAP note), and that means more than 50% of people on the world are affected by disasters. Therefore, the information on people distribution in the disaster or hazard zone is important in order to mitigate the impact of natural disasters. Especially for tsunami, this information will help the government to better manage the evacuation of people and to estimate the number of people affected if there is tsunami event in their area. Normally, the available information on population distribution is based statistical data related to administrative boundaries, e.g. village, municipal, district, province, or national level. This research focuses on the improvement of the spatial resolution of data on the people distribution covering the area along the west coast Sumatera, South Coast of Java, and Bali. The results are used as an input for tsunami risk assessment in the framework of the GITEWS project. A combination of the number of people at village level with land use maps is under¬taken in this research. GIS and remote sensing techniques are used to improve the spatial detail of statistical data on people distribution. The model is based on an analysis of people activities in a certain land use. To assign appropriate weighting factors, census data and potential of village (PODES) data are used. The results of this research are detailed people distribution maps (day and night time) for the Coast of Sumatera, South Coast of Java, and Coastal of Bali. The spatial improvement can be shown. Moreover, besides the spatial improvement, the results also provide information on the distribution during day and night time. To estimate the accuracy of this approach, sensitivity analyses have been performed, which show the quality of the results. Keywords: spatial improvement, people distribution, census, land use, risk assessment

Khomarudin, R.; Strunz, G.; Post, J.; Zosseder, K.; Ludwig, R.

2009-04-01

65

Instrument requirements for imaging the magnetosphere in extreme-ultraviolet and energetic neutral atoms derived from computer-simulated images  

NASA Technical Reports Server (NTRS)

Scientific requirements for He(+)(304 A) and energetic neutral atom (ENA) magnetospheric imaging, as well as the derived instrumental requirements are presented. Both ENA imaging of the hot plasma and EUV imaging of the cold plasma are highlighted. The question of the accuracy with which physically significant parameters can be extracted from actual images using computerized algorithms is addressed. An example of an ENA image analyzed by means of the Powell minimization algorithm is given. Automated unfolding of global magnetospheric images is also discussed. A Mercator projection of a model INA image is shown.

Roelof, Edmond C.; Mauk, Barry H.; Meier, Robert R.

1992-01-01

66

Assessing the impact of uncertainties and errors on multi-criteria evaluation procedures when using remote sensing derived land cover input data  

NASA Astrophysics Data System (ADS)

Spatial decision-making procedures, such as multi-criteria evaluation (MCE), often rely upon input data derived from remote sensing in the form of land cover maps. However, these data can often contain inherent errors and misclassifications that can influence the accuracy of the final output associated with spatial decision-making procedures. The research presented here explores what influence errors and misclassifications in remote sensing derived land cover data can have on the output from spatial decision-making procedures. Four land cover data layers, each covering the same spatial area and easily obtained from scholarly or governmental institutions, are used throughout this research. These comparative land cover data layers are compared with an author-created land cover data layer known as the BASE layer. The BASE layer represents the nearest approximation of the land cover condition in the study region. Overall land cover classification accuracy is assessed for each of the land cover data layers used in this research. In addition to overall land cover classification accuracy, classification accuracy is evaluated along the edge and interior of land cover regions in order to determine if the spatial location of errors and misclassifications, rather than the quantity of errors and misclassifications alone, can have an impact on the output form spatial decision making procedures. This is followed by an assessment of the influence of errors and misclassifications on site and situational factors, two of the primary components of spatial decision-making procedures. Direct comparisons are made between the BASE layer and the comparative land cover data layers. A series of multi-criteria evaluation procedures using the BASE layer and the four comparative data layers as input concludes this research. The output from the spatial decision-making procedure using the BASE layer is directly compared with the same spatial decision-making procedure using each of the comparative land cover data layers as input. Differences between the BASE layer and the comparative land cover data layers are then assessed to determine if errors and misclassifications have had an impact on the output of the spatial decision-making procedures.

Huffman, French Tyler

67

Speckle Noise Reduction in Ultrasound Biomedical B-Scan Images Using Discrete Topological Derivative  

Microsoft Academic Search

Over three decades, several despeckling techniques have been developed by researchers to reduce the speckle noise inherently present in ultrasound B-scan images without losing the diagnostic information. The topological derivative (TD) is the recently adopted technique in the area of biomedical image processing. In this work, we computed the topological derivative for an appropriate function associated to the ultrasound B-scan

D. Nedumaran; R. Sivakumar; V. Sekar; M. K. Gayathri

68

The least-squares mixing models to generate fraction images derived from remote sensing multispectral data  

NASA Technical Reports Server (NTRS)

Constrained-least-squares and weighted-least-squares mixing models for generating fraction images derived from remote sensing multispectral data are presented. An experiment considering three components within the pixels-eucalyptus, soil (understory), and shade-was performed. The generated fraction images for shade (shade image) derived from these two methods were compared by considering the performance and computer time. The derived shade images are related to the observed variation in forest structure, i.e., the fraction of inferred shade in the pixel is related to different eucalyptus ages.

Shimabukuro, Yosio Edemir; Smith, James A.

1991-01-01

69

Fluorophor-labeled spermidine derivatives as fluorescent markers in optical tumor imaging.  

PubMed

Up-regulation of polyamine transporters on the surface of tumor cells and the internalization of biogenic polyamines by active transport processes may be exploited for the accumulation of spermidine derivatives as reporter molecules. We have synthesized and tested fluorophor-labeled spermidine derivatives for the development of a new class of intraoperative tumor imaging agents. In vitro uptake experiments and initial in vivo imaging studies illustrated that fluorophor tagged spermidine derivatives show tumor accumulation. PMID:16621552

Wolf, Markus; Bauder-Wüst, Ulrike; Pipkorn, Rüdiger; Eskerski, Helmut; Eisenhut, Michael

2006-06-15

70

First bodipy-DOTA derivatives as probes for bimodal imaging.  

PubMed

The synthesis and the photophysical studies of the first bodipy-DOTA and its In(III), Ga(III) and Cu(II) complexes are reported. The introduction of an isothiocyanate handle generates a new bimodal imaging agent capable of both optical and nuclear imaging. PMID:20877903

Bernhard, Claire; Goze, Christine; Rousselin, Yoann; Denat, Franck

2010-11-21

71

Electron transfer reactions for image and image-derived states in dielectric thin films  

NASA Astrophysics Data System (ADS)

We have studied the cross section for electron trapping that occurs at the surfaces and interfaces of a variety of thin dielectric films (n-octane, methanol, n-butanol, and difluoromethane) that are grown on Kr buffer films. When such films are bombarded with electrons of very low incident energies (E<~300 meV), charging cross sections up to the order of 10-14 cm2 are measured for submonolayer quantities of a variety of coadsorbed molecules: CH3I, CH3Br, CH3Cl, and CO2. These huge cross sections are ascribed to the formation of image states at the dielectric film interfaces, which trap incoming electrons and, via coupling to the adsorbate electron affinity levels, dramatically enhance the capture probability. We have also shown that thin film dielectric layer structures can be created which display image-derived states, such as a ``quantum well'' in a sandwich structure with two ``electron barrier'' layers surrounding a Kr and adsorbate spacer film. These phenomena are shown to be of a general nature, occurring for a wide variety of molecular thin films, and depend on the dielectric constant and electron affinity of the selected species. We also report the absolute cross section for dissociative electron attachment of submonolayer CH3I adsorbed on Kr thin films.

Jensen, E. T.; Sanche, L.

2008-08-01

72

Boundary estimation of fiber bundles derived from diffusion tensor images  

Microsoft Academic Search

Purpose  Diffusion tensor imaging (DTI) is a non-invasive imaging technique that allows estimating the location of white matter tracts\\u000a based on the measurement of water diffusion properties. Using DTI data, the fiber bundle boundary can be determined to gain\\u000a information about eloquent structures, which is of major interest for neurosurgical interventions. In this paper, a novel\\u000a approach for boundary estimation is

Miriam Helen Anna Bauer; Sebastiano Barbieri; Jan Klein; Jan Egger; Daniela Kuhnt; Bernd Freisleben; Horst Karl Hahn; Christopher Nimsky

2011-01-01

73

Shear-wave velocity profile and seismic input derived from ambient vibration array measurements: the case study of downtown L'Aquila  

NASA Astrophysics Data System (ADS)

Downtown L'Aquila suffered severe damage (VIII-IX EMS98 intensity) during the 2009 April 6 Mw 6.3 earthquake. The city is settled on a top flat hill, with a shear-wave velocity profile characterized by a reversal of velocity at a depth of the order of 50-100 m, corresponding to the contact between calcareous breccia and lacustrine deposits. In the southern sector of downtown, a thin unit of superficial red soils causes a further shallow impedance contrast that may have influenced the damage distribution during the 2009 earthquake. In this paper, the main features of ambient seismic vibrations have been studied in the entire city centre by using array measurements. We deployed six 2-D arrays of seismic stations and 1-D array of vertical geophones. The 2-D arrays recorded ambient noise, whereas the 1-D array recorded signals produced by active sources. Surface-wave dispersion curves have been measured by array methods and have been inverted through a neighbourhood algorithm, jointly with the H/V ambient noise spectral ratios related to Rayleigh waves ellipticity. We obtained shear-wave velocity (Vs) profiles representative of the southern and northern sectors of downtown L'Aquila. The theoretical 1-D transfer functions for the estimated Vs profiles have been compared to the available empirical transfer functions computed from aftershock data analysis, revealing a general good agreement. Then, the Vs profiles have been used as input for a deconvolution analysis aimed at deriving the ground motion at bedrock level. The deconvolution has been performed by means of EERA and STRATA codes, two tools commonly employed in the geotechnical engineering community to perform equivalent-linear site response studies. The waveform at the bedrock level has been obtained deconvolving the 2009 main shock recorded at a strong motion station installed in downtown. Finally, this deconvolved waveform has been used as seismic input for evaluating synthetic time-histories in a strong-motion target site located in the middle Aterno river valley. As a target site, we selected the strong-motion station of AQV 5 km away from downtown L'Aquila. For this site, the record of the 2009 L'Aquila main shock is available and its surface stratigraphy is adequately known making possible to propagate the deconvolved bedrock motion back to the surface, and to compare recorded and synthetic waveforms.

Di Giulio, Giuseppe; Gaudiosi, Iolanda; Cara, Fabrizio; Milana, Giuliano; Tallini, Marco

2014-08-01

74

Fluorescent fructose derivatives for imaging breast cancer cells.  

PubMed

Breast cancer cells are known to overexpress Glut5, a sugar transporter responsible for the transfer of fructose across the cell membrane. Since Glut5 transporter is not significantly expressed in normal breast cells, fructose uptake can potentially be used to differentiate between normal and cancerous cells. Fructose was labeled with two fluorophores at the C-1 position: 7-nitro-1,2,3-benzadiazole (NBD) and Cy5.5. The labeling site was chosen on the basis of the presence and substrate specificity of the key proteins involved in the first steps of fructose metabolism. Using fluorescence microscopy, the uptake of the probes was studied in three breast cancer cell lines: MCF 7, MDA-MB-435, and MDA-MB-231. Both fluorescent fructose derivatives showed a very good uptake in all tested cell lines. The level of uptake was comparable to that of the corresponding glucose analogs, 2-NBDG and Cy5.5-DG. Significant uptake of 1-NBDF derivative was not observed in cells lacking Glut5 transporter, while the uptake of the 1-Cy5.5-DF derivative was independent of the presence of a fructose-specific transporter. While 1-NBDF showed Glut5-specific accumulation, the coupling of a large fluorophore such as Cy5.5 likely introduces big structural and electronic changes, leading to a fructose derivative that does not accurately describe the uptake of fructose in cells. PMID:17444608

Levi, Jelena; Cheng, Zhen; Gheysens, Olivier; Patel, Manish; Chan, Carmel T; Wang, Yingbing; Namavari, Mohammad; Gambhir, Sanjiv Sam

2007-01-01

75

High resolution Vesta HAMO atlas derived from Dawn FC images.  

NASA Astrophysics Data System (ADS)

NASA's Dawn spacecraft entered orbit of the inner main belt asteroid 4 Vesta on July 16, 2011, and is spending one year in orbit to characterize the geology, elemental and mineralogical composition, topography, shape, and internal structure of Vesta before departing to asteroid 1 Ceres in late 2012. The Dawn mission is mapping Vesta from three different orbit heights during Survey orbit (2700 km altitude), HAMO (High Altitude Mapping Orbit, 700 km altitude), and LAMO (Low Altitude Mapping Orbit, 210 km altitude). Dawn orbited Vesta during HAMO in 6 cycles between end of September end early November 2011. The framing camera took about 2,500 clear filter images with a resolution of about 70 m/pixel during these cycles. The images were taken with different viewing angles and different illumination conditions. We selected images from one cycle (cycle #3) for the mosaicking process to have similar viewing and illumination conditions. Cycle 3 with 518 images was selected since it was the first cycle with almost complete global coverage.The Vesta atlas was produced in a scale of 1:500,000 and consists of 15 tiles that conform to the quadrangle scheme whoich is widely used for small planetray bodies.

Roatsch, T.; Kersten, E.; Matz, K.-D.; Preusker, F.; Scholten, F.; Jaumann, R.; Raymond, C. A.; Russell, C. T.

2012-04-01

76

Using Catastrophe Theory to Derive Trees from Images  

Microsoft Academic Search

In order to investigate the deep structure of Gaussian scale space images, one needs to understand the behaviour of critical points under the influence of blurring. We show how the mathematical framework of catastrophe theory can be used to describe the different types of annihilations and the creation of pairs of critical points and how this knowledge can be exploited

Arjan Kuijper; LUC M. J. FLORACK

2005-01-01

77

An investigation into the effect of input function shape and image acquisition interval on estimates of washin for dynamic cardiac SPECT  

NASA Astrophysics Data System (ADS)

Dynamic cardiac SPECT and PET can be used to measure myocardial perfusion by estimating the kinetic rate constant describing the washin of radioactive-labelled tracers from the blood to the extravascular myocardial tissue. Because of differences in photon statistics and data acquisition techniques, protocols which produce optimal estimates of the washin for dynamic cardiac PET may give suboptimal estimates if applied in dynamic cardiac SPECT. Two important factors in the estimation of washin are the shape of the tracer input function and the image acquisition interval. This study uses computer simulations to investigate the effect of varying the tracer infusion length and image acquisition interval on the bias and variance of estimates of washin obtained with dynamic cardiac SPECT and images/0031-9155/42/11/014/img7.gif" ALIGN="TOP"/>-labelled teboroxime. Bias in parameter estimates can be introduced by aliasing, integration of the time-varying radioactivity by the detector, and detector motion. This bias can be reduced by decreasing the acquisition interval and using a longer-duration input function. However, this results in poor photon statistics, which generate large variance, and can also introduce bias in the estimates of the washin. Our studies indicate that better estimates of the washin are obtained by using an acquisition interval that is of sufficient duration to obtain adequate photon statistics even if this is at the expense of temporal resolution. The increase in bias caused by using a 10 or 20 s acquisition interval instead of a 5 s acquisition interval is minimal when compared with the reduction in variance. Variance in estimates is also reduced by using a sharp input function, resulting in higher peak counts during washin. It is also shown that the variance of estimates of the washin increases generally when faster kinetics are observed. This variance can, however, be reduced by using longer acquisition intervals.

Ross, Steven G.; Welch, Andy; Gullberg, Grant T.; Huesman, Ronald H.

1997-11-01

78

Image-Derived Prediction of Spectral Image Utility for Target Detection Applications  

Microsoft Academic Search

The utility of an image is an attribute that describes the ability of that image to satisfy performance requirements for a particular application. Building on previous research that defines the assessment of the utility of a spectral image based on the detectability of subpixel targets, this paper examines the prediction of spectral image utility. It first reviews existing methods for

Marcus S. Stefanou; John P. Kerekes

2010-01-01

79

Multidimensional mutual information image similarity metrics based on derivatives of linear scale-space  

Microsoft Academic Search

We propose a new voxel similarity measure which uses local image structure as well as intensity information. The derivatives of linear scale space are used to provide struc- tural information in the form of a feature vector for each voxel. Each scale space derivative is assigned to its own in- formation channel. We illustrate the behavior of the similar- ity

Mark Holden; Lewis D. Griffin; Derek L. G. Hill

80

Guided Image Filtering  

Microsoft Academic Search

In this paper, we propose a novel type of explicit image fil- ter - guided filter. Derived from a local linear model, the guided filter generates the filtering output by considering the content of a guidance image, which can be the input image itself or another different image. The guided filter can perform as an edge-preserving smoothing opera- tor like

Kaiming He; Jian Sun; Xiaoou Tang

2010-01-01

81

No-reference image quality assessment based on log-derivative statistics of natural scenes  

NASA Astrophysics Data System (ADS)

We propose an efficient blind/no-reference image quality assessment algorithm using a log-derivative statistical model of natural scenes. Our method, called DErivative Statistics-based QUality Evaluator (DESIQUE), extracts image quality-related statistical features at two image scales in both the spatial and frequency domains. In the spatial domain, normalized pixel values of an image are modeled in two ways: pointwise-based statistics for single pixel values and pairwise-based log-derivative statistics for the relationship of pixel pairs. In the frequency domain, log-Gabor filters are used to extract the fine scales of the image, which are also modeled by the log-derivative statistics. All of these statistics can be fitted by a generalized Gaussian distribution model, and the estimated parameters are fed into combined frameworks to estimate image quality. We train our models on the LIVE database by using optimized support vector machine learning. Experiment results tested on other databases show that the proposed algorithm not only yields a substantial improvement in predictive performance as compared to other state-of-the-art no-reference image quality assessment methods, but also maintains a high computational efficiency.

Zhang, Yi; Chandler, Damon M.

2013-10-01

82

Automated Computer-derived Prostate Volumes from MR Imaging Data: Comparison with Radiologist-derived MR Imaging and Pathologic Specimen Volumes  

PubMed Central

Purpose: To compare prostate gland volume (PV) estimation of automated computer-generated multifeature active shape models (MFAs) performed with 3-T magnetic resonance (MR) imaging with that of other methods of PV assessment, with pathologic specimens as the reference standard. Materials and Methods: All subjects provided written informed consent for this HIPAA-compliant and institutional review board–approved study. Freshly weighed prostatectomy specimens from 91 patients (mean age, 59 years; range, 42–84 years) served as the reference standard. PVs were manually calculated by two independent readers from MR images by using the standard ellipsoid formula. Planimetry PV was calculated from gland areas generated by two independent investigators by using manually drawn regions of interest. Computer-automated assessment of PV with an MFA was determined by the aggregate computer-calculated prostate area over the range of axial T2-weighted prostate MR images. Linear regression, linear mixed-effects models, concordance correlation coefficients, and Bland-Altman limits of agreement were used to compare volume estimation methods. Results: MFA-derived PVs had the best correlation with pathologic specimen PVs (slope, 0.888). Planimetry derived volumes produced slopes of 0.864 and 0.804 for two independent readers when compared with specimen PVs. Ellipsoid formula–derived PVs had slopes closest to one when compared with planimetry PVs. Manual MR imaging and MFA PV estimates had high concordance correlation coefficients with pathologic specimens. Conclusion: MFAs with axial T2-weighted MR imaging provided an automated and efficient tool with which to assess PV. Both MFAs and MR imaging planimetry require adjustments for optimized PV accuracy when compared with prostatectomy specimens. © RSNA, 2012

Bulman, Julie C.; Toth, Robert; Patel, Amish D.; Bloch, B. Nicolas; McMahon, Colm J.; Ngo, Long; Madabhushi, Anant

2012-01-01

83

Imaging and Tracking of Bone Marrow-Derived Immune and Stem Cells  

PubMed Central

Bone marrow (BM)-derived stem and immune cells play critical roles in maintaining the health, regeneration, and repair of many tissues. Given their important functions in tissue regeneration and therapy, tracking the dynamic behaviors of BM-derived cells has been a long-standing research goal of both biologists and engineers. Because of the complex cellular-level processes involved, real-time imaging technologies that have sufficient spatial and temporal resolution to visualize them are needed. In addition, in order to track cellular dynamics, special attention is needed to account for changes in the microenvironment where the cells reside, for example, tissue contraction, stretching, development, etc. In this chapter, we introduce methods for real-time imaging and longitudinal tracking of BM-derived immune and stem cells in in vivo three-dimensional (3-D) tissue environments with an integrated optical microscope. The integrated microscope combines multiple imaging functions derived from optical coherence tomography (OCT) and multiphoton microscopy (MPM), including optical coherence microscopy (OCM), micro-vasculature imaging, two-photon excited fluorescence (TPEF), and second harmonic generation (SHG) microscopy. Short- and long-term tracking of the dynamic behavior of BM-derived cells involved in cutaneous wound healing and skin grafting in green fluorescent protein (GFP) BM-transplanted mice is demonstrated. Methods and algorithms for nonrigid registration of time-lapse images are introduced, which allows for long-term tracking of cell dynamics over several months.

Zhao, Youbo; Bower, Andrew J.; Graf, Benedikt W.; Boppart, Marni D.; Boppart, Stephen A.

2014-01-01

84

A complementary dual-slope ADC with high frame rate and wide input range for fast X-ray imaging  

NASA Astrophysics Data System (ADS)

The single-slope analog-to-digital converter (SS-ADC) is the most commonly used column-level ADC for high-speed industrial, complementary metal-oxide semiconductor (CMOS)-based X-ray image sensors because of its small chip area (the width of a pixel), its simple circuit structure, and its low power consumption. However, it generally has a long conversion time, so we propose an innovative design: a complimentary dual-slope ADC (CDS-ADC) that uses two opposite ramp signals instead of a single ramp to double the conversion speed. This CDS-ADC occupies only 15% more area than the original SS-ADC. A prototype 12-bit CDS-ADC and a 12-bit SS-ADC were fabricated using a 0.35-µm 1P 4M CMOS process. During comparison of the two, the measured maximum differential non-linearity (DNL) of the CDS-ADC was a 0.49 least significant bit (LSB), the maximum integral non-linearity (INL) was a 0.43 LSB, the effective number of bits (ENOB) was 9.18 bits, and the figure of merit (FOM) was 0.03 pJ/conversion. The total power consumption was 0.031 uW. The conversion time of the new CDS-ADC was half that of the SS-ADC. The proposed dual-slope concept can be extended to further multiply the conversion speed by using multiple pairs of dual-slope ramps.

Lee, Daehee; Cho, Minsik; Kang, Dong-Uk; Kim, Myung Soo; Kim, Hyunduk; Cho, Gyuseong

2014-02-01

85

In vivo imaging of zebrafish retinal cells using fluorescent coumarin derivatives  

PubMed Central

Background The zebrafish visual system is a good research model because the zebrafish retina is very similar to that of humans in terms of the morphologies and functions. Studies of the retina have been facilitated by improvements in imaging techniques. In vitro techniques such as immunohistochemistry and in vivo imaging using transgenic zebrafish have been proven useful for visualizing specific subtypes of retinal cells. In contrast, in vivo imaging using organic fluorescent molecules such as fluorescent sphingolipids allows non-invasive staining and visualization of retinal cells en masse. However, these fluorescent molecules also localize to the interstitial fluid and stain whole larvae. Results We screened fluorescent coumarin derivatives that might preferentially stain neuronal cells including retinal cells. We identified four coumarin derivatives that could be used for in vivo imaging of zebrafish retinal cells. The retinas of living zebrafish could be stained by simply immersing larvae in water containing 1 ?g/ml of a coumarin derivative for 30 min. By using confocal laser scanning microscopy, the lamination of the zebrafish retina was clearly visualized. Using these coumarin derivatives, we were able to assess the development of the zebrafish retina and the morphological abnormalities induced by genetic or chemical interventions. The coumarin derivatives were also suitable for counter-staining of transgenic zebrafish expressing fluorescent proteins in specific subtypes of retinal cells. Conclusions The coumarin derivatives identified in this study can stain zebrafish retinal cells in a relatively short time and at low concentrations, making them suitable for in vivo imaging of the zebrafish retina. Therefore, they will be useful tools in genetic and chemical screenings using zebrafish to identify genes and chemicals that may have crucial functions in the retina.

2010-01-01

86

Long-term exclusion of plant-inputs to soil reduces the functional capacity of microbial communities to mineralise recalcitrant root-derived carbon sources  

Microsoft Academic Search

Microbial communities in soil are highly species-rich, recognition of which has led to the view that functional redundancy within communities may buffer many impacts of altered community structure on soil functions. In this study we investigated the impact of long-term (>50 years) exclusion of plant-inputs (bare-fallow treatment) on soil microbial community structure and on the ability of the microbial biomass to

Eric Paterson; Allan Sim; Shona M. Osborne; Phil J. Murray

2011-01-01

87

Mapping of photon distribution and imaging of MR-derived anatomically accurate optical models of the female breast  

Microsoft Academic Search

We have computed optical images of the female breast based on analysis of tomographic data obtained from simulated time-independent optical measurements of anatomically accurate maps derived from segmented 3D magnetic resonance (MR) images. Images were segmented according to the measured MR contrast levels for fat and parenchymal tissue from T1 weighted acquisitions. Computed images were obtained from analysis of solutions

San-Lian S. Barbour; Randall L. Barbour; Ping C. Koo; Harry L. Graber; Jenghwa Chang

1995-01-01

88

Resolution and shutter speed measurements of an MCPII with a 270-ps whole image shutter for a point-source input  

SciTech Connect

The modulation transfer function (MF) of a shuttered, 18-mm-diameter, proximity-focused microchemical-plate image intensifier (MCPII) was measured as a function of time in the shutter sequence. Electrical gate pulses were delivered to the MCPII with microstrip impedance transformers for reduced pulse dispersion and reflections. Using 30 ps FWHM, 600 nm pulses from a sync-pumped dye, argon-ion laser as a probe, the MCPII`s shutter speed for point-source (6-{mu}m-diameter) illumination and 230 ps FWHM, {minus}590 V gate pulses was measured to be between 200 and 250 ps FWHM. The MF of the MCPII was measured by analyzing the point spread function (PSF) for inputs at several different locations on the MCPII and at different times in the shuttering sequence. The best 50% MF resolution of 16.2 lp/mm was found with illumination near the edge where the gate pulse enters the MCPII and at 120 ps into the shutter sequence. The whole image (18-mm-diameter) shutter speed (off-to-off) of the MCPII was measured to be 270 ps.

Thomas, M.C. [Special Technologies Lab., Santa Barbara, CA (United States); Yates, G.J. [Los Alamos National Lab., NM (United States); Zagarino, P. [Sharpenit, Ellwood, CA (United States)

1995-07-01

89

Development of a pulse programmer for magnetic resonance imaging using a personal computer and a high-speed digital input-output board  

NASA Astrophysics Data System (ADS)

We have developed a pulse programmer for magnetic resonance imaging (MRI) using a personal computer and a commercially available high-speed digital input-output board. The software for the pulse programmer was developed using C/C++ and .NET Framework 2.0 running under the Windows 7 operating system. The pulse programmer was connected to a digital MRI transceiver using a 32-bit parallel interface, and 128-bit data (16 bits × 8 words) for the pulse sequence and the digitally detected MRI signal were transferred bi-directionally every 1 ?s. The performance of the pulse programmer was evaluated using a 1.0 T permanent magnet MRI system. The acquired MR images demonstrated the usefulness of the pulse programmer. Although our pulse programmer was developed for a specially designed digital MRI transceiver, our approach can be used for any MRI system if the interface for the transceiver is properly designed. Therefore, we have concluded that our approach is promising for MRI pulse programmers.

Hashimoto, Seitaro; Kose, Katsumi; Haishi, Tomoyuki

2012-05-01

90

Properties of the Water Column and Bottom Derived from Airborne Visible Infrared Imaging Spectrometer (AVIRIS) Data  

Microsoft Academic Search

Using Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data as an example, we show in this study that the properties of the water column and bottom of a large, shallow area can be adequately retrieved using a model-driven optimization technique. The simultaneously derived properties include bottom depth, bottom albedo, and water absorption and backscattering coefficients, which in turn could be used

ZhongPing Lee; Kendall L. Carder; Robert F. Chen; Thomas G. Peacock

2001-01-01

91

Image method for the derivation of point sources in elastostatic problems with plane interfaces  

NASA Technical Reports Server (NTRS)

An image method algorithm is presented for the derivation of point sources of elastostatics in multilayered media assuming the infinite space point source is known. Specific cases were worked out and shown to coincide with well known solutions in the literature.

Fares, Nabil; Li, Victor C.

1986-01-01

92

Solar Subsurface Fluid Dynamics Descriptors Derived from Global Oscillation Network Group and Michelson Doppler Imager Data  

Microsoft Academic Search

We analyze Global Oscillation Network Group (GONG) and Michelson Doppler Imager (MDI) observations obtained during Carrington rotation 1988 (2002 March 30-April 26) with a ring-diagram technique in order to measure the zonal and meridional flow components in the upper solar convection zone. We derive daily flow maps over a range of depths up to 16 Mm on a spatial grid

R. Komm; T. Corbard; B. R. Durney; I. González Hernández; F. Hill; R. Howe; C. Toner

2004-01-01

93

The benefits of using short interval satellite images to derive winds for tropical cyclones  

NASA Technical Reports Server (NTRS)

During the 1975, 1976, and 1977, NOAA's National Environmental Satellite Service and NASA's Goddard Space Flight Center conducted a cooperative program to determine the optimum resolution and frequency of satellite images for deriving winds to study and forecast tropical cyclones. Rapid scan images were obtained at 7.5 minute interval from SMS-2 for hurricane Eloise and cyclone Caroline, and at 3 minute intervals from GOES-1 for tropical storms Belle, Holly, and Anita. Cloud motions were derived from these images using the Atmospheric and Oceanographic Information Processing System. Winds that were derived from the movement of upper and lower tropospheric level clouds using rapid scan data were compared with the 15 and 30 minute interval data. Greater than 10 (5) times as many clouds could be tracked to obtain winds using 3 and 7.5 minute rapid scan images as when using 15 or 30 minute interval images. A few bright areas within the central dense overcast which appeared to be moving with the winds at low levels were tracked.

Rodgers, E.; Gentry, R. C.; Shenk, W. E.; Oliver, V.

1978-01-01

94

Tri-stereo Pleiades images-derived digital surface models for tectonic geomorphology studies  

NASA Astrophysics Data System (ADS)

Very high resolution digital elevation models are a key component of modern quantitative geomorphology. In parallel to high-precision but time-consuming kinematic GPS and/or total station surveys and dense coverage but expensive LiDAR campaigns, we explore the usability of affordable, flexible, wide coverage digital surface models (DSMs) derived from Pleiades tri-stereo optical images. We present two different approaches to extract DSM from a triplet of images. The first relies on the photogrammetric extraction of 3 DSMs from the 3 possible stereo couples and subsequent merge based on the best correlation score. The second takes advantage of simultaneous correlation over the 3 images to derive a point cloud. We further extract DSM from panchromatic 0.5 m resolution images and multispectral 2 m resolution images to test for correlation and noise and determine optimal correlation window size and achievable resolution. Georeferencing is also assessed by comparing raw coordinates derived from Pleiades Rational Polynomial Coefficients to ground control points. Primary images appear to be referenced within ~15 m over flat areas where parallax is minimal while derived DSMs and associated orthorectified images show a much improved referencing within ~5 m of GCPs. In order to assess the adequacy of Pleiades DSMs for tectonic geomorphology, we present examples from case studies along the Trougout normal fault (Morocco), the Hovd strike-slip fault (Mongolia), the Denali strike-slip fault (USA and Canada) and the Main Frontal Thrust (Bhutan). In addition to proposing a variety of tectonic contexts, these examples cover a wide range of climatic conditions (semi-arid, arctic and tropical), vegetation covers (bare earth, sparse Mediterranean, homogeneous arctic pine, varied tropical forest), lithological natures and related erosion rates. The capacity of derived DSMs is demonstrated to characterize geomorphic markers of active deformation such as marine and alluvial terraces, stream gullies, alluvial fans and fluvio-glacial deposits in terms of vertical (from DSMs) and horizontal (from orthorectified optical images) offsets. Values extracted from Pleiades DSMs compare well to field measurements in terms of relief and slope, which suggests effort and resources necessary for field topography could be significantly reduced, especially in poorly accessible areas.

Ferry, Matthieu; Le Roux-Mallouf, Romain; Ritz, Jean-François; Berthet, Théo; Peyret, Michel; Vernant, Philippe; Maréchal, Anaïs; Cattin, Rodolphe; Mazzotti, Stéphane; Poujol, Antoine

2014-05-01

95

A new method of phase derivative extracting for off-axis quantitative phase imaging  

NASA Astrophysics Data System (ADS)

We present a new derivative method for phase information extraction in off-axis quantitative phase imaging (QPI). Similar to other rapid derivative method, this method only uses the interference term, the 1st and 2nd order derivatives of a single interferogram in QPI, but the assumption in our method is different from that of other derivative method. And this method can be used to optimize small spatial frequency processing capability in slightly off-axis QPI. We illustrate the proposed method with theory and simulation experiment of a ball, and prove our method by comparing our simulation results with the experimental results of the red blood cell and the skin cancer cell, respectively.

Xu, Yuanyuan; Wang, Yawei; Jin, Weifeng; Lv, Cuihong; Wu, Hui

2013-09-01

96

Spatially Variant Positron Range Modeling Derived from CT for PET Image Reconstruction  

PubMed Central

The influence of a finite positron annihilation distance represents a fundamental limit to the spatial resolution of PET scanners. It is appreciated that this effect is a minor concern in whole-body F18 imaging, but it does represent an issue when imaging with higher energy isotopes such as N13 or Rb82. This effect is especially relevant for imaging tasks along tissue gradients such as the cardiac/lung boundary and diaphragm/lung boundary. This work presents a method to determine the positron range effect from a CT scan and to model this effect as shift-variant, anisotropic kernels. The positron annihilation distance across boundaries of tissues is represented with a simple model, which can be quickly derived from CT scans and applied in the reconstruction of PET images. The positron range compensation map is applied in a modified OSEM algorithm to simulated and measured data.

Alessio, Adam; MacDonald, Lawrence

2009-01-01

97

Video image-based analysis of single human induced pluripotent stem cell derived cardiomyocyte beating dynamics using digital image correlation  

PubMed Central

Background The functionality of a cardiomyocyte is primarily measured by analyzing the electrophysiological properties of the cell. The analysis of the beating behavior of single cardiomyocytes, especially ones derived from stem cells, is challenging but well warranted. In this study, a video-based method that is non-invasive and label-free is introduced and applied for the study of single human cardiomyocytes derived from induced pluripotent stem cells. Methods The beating of dissociated stem cell-derived cardiomyocytes was visualized with a microscope and the motion was video-recorded. Minimum quadratic difference, a digital image correlation method, was used for beating analysis with geometrical sectorial cell division and radial/tangential directions. The time series of the temporal displacement vector fields of a single cardiomyocyte was computed from video data. The vector field data was processed to obtain cell-specific, contraction-relaxation dynamics signals. Simulated cardiomyocyte beating was used as a reference and the current clamp of real cardiomyocytes was used to analyze the electrical functionality of the beating cardiomyocytes. Results Our results demonstrate that our sectorized image correlation method is capable of extracting single cell beating characteristics from the video data of induced pluripotent stem cell-derived cardiomyocytes that have no clear movement axis, and that the method can accurately identify beating phases and time parameters. Conclusion Our video analysis of the beating motion of single human cardiomyocytes provides a robust, non-invasive and label-free method to analyze the mechanobiological functionality of cardiomyocytes derived from induced pluripotent stem cells. Thus, our method has potential for the high-throughput analysis of cardiomyocyte functions.

2014-01-01

98

In vivo imaging of human adipose-derived stem cells in Alzheimer's disease animal model  

NASA Astrophysics Data System (ADS)

Stem cell therapy is a promising tool for the treatment of diverse conditions, including neurodegenerative diseases such as Alzheimer's disease (AD). To understand transplanted stem cell biology, in vivo imaging is necessary. Nanomaterial has great potential for in vivo imaging and several noninvasive methods are used, such as magnetic resonance imaging, positron emission tomography, fluorescence imaging (FI) and near-infrared FI. However, each method has limitations for in vivo imaging. To overcome these limitations, multimodal nanoprobes have been developed. In the present study, we intravenously injected human adipose-derived stem cells (hASCs) that were labeled with a multimodal nanoparticle, LEO-LIVE™-Magnoxide 675 or 797 (BITERIALS, Seoul, Korea), into Tg2576 mice, an AD mouse model. After sequential in vivo tracking using Maestro Imaging System, we found fluorescence signals up to 10 days after injection. We also found strong signals in the brains extracted from hASC-transplanted Tg2576 mice up to 12 days after injection. With these results, we suggest that in vivo imaging with this multimodal nanoparticle may provide a useful tool for stem cell tracking and understanding stem cell biology in other neurodegenerative diseases.

Ha, Sungji; Ahn, Sangzin; Kim, Saeromi; Joo, Yuyoung; Chong, Young Hae; Suh, Yoo-Hun; Chang, Keun-A.

2014-05-01

99

(abstract) Monitoring Seasonal State and Mapping Species in Alaskan Taiga Using Imaging Radar as Input to CO(sub 2) Flux Models  

NASA Technical Reports Server (NTRS)

Changes in the seasonal CO(sub 2) flux of the boreal forests may result from increased atmospheric CO(sub 2) concentrations and associated atmospheric warming. To monitor this potential change, a combination of remote sensing information and ecophysiological models are required. In this paper we address the use of synthetic aperture radar (SAR) data to provide some of the input to the ecophysiological models: forest type, freeze/thaw state which limits the growing season for conifers, and leaf on/off state which limits the growing season for deciduous species. AIRSAR data collected in March 1988 during an early thaw event and May 1991 during spring breakup are used to generate species maps and to determine the sensitivity of SAR to canopy freeze/thaw transitions. These data are also used to validate a microwave scattering model which is then used to determine the sensitivity of SAR to leaf on/off and soil freeze/thaw transitions. Finally, a CO(sub 2) flux algorithm which utilizes SAR data and an ecophysiological model to estimate CO(sub 2) flux is presented. CO(sub 2) flux maps are generated from which areal estimates of CO(sub 2) flux are derived.

Way, J. B.; Rignot, E.; McDonald, K.; Adams, P.; Viereck, L.

1993-01-01

100

Monitoring seasonal state and mapping species in Alaskan taiga using imaging radar as input to CO[sub 2] flux models  

SciTech Connect

Changes in the seasonal CO[sub 2] flux of the boreal forests may result from increased atmospheric CO[sub 2] concentrations and associated atmospheric warming. To monitor this potential change, a combination of remote sensing information and ecophysiological models are required. In this paper we address the use of synthetic aperture radar (SAR) data to provide some of the input to the ecophysiological models: forest type, freeze/thaw state which limits the growing season for conifers, and leaf on/off state which limits the growing season for deciduous species. AIRSAR data collected in March 1988 during an early thaw event and May 1991 during spring breakup are used to generate species maps and to determine the sensitivity of SAR to canopy freeze/thaw transitions. These data are also used to validate a microwave scattering model which is then used to determine the sensitivity of SAR to leaf on/off and soil freeze/thaw transitions. Finally, a CO[sub 2] flux algorithm which utilizes SAR data and an ecophysiological model to estimate CO[sub 2] flux is presented. CO[sub 2] flux maps are generated from which areal estimates of CO[sub 2] flux are derived. This work was carried out at the Jet Propulsion Laboratory under contract to the NASA.

Way, J.B.; Rignot, E.; McDonald, K.; Adams, P.; Viereck, L. (Jet Propulsion Lab., Pasadena, CA (United States) Institute of Northern Forestry, Fairbanks, AK (United States))

1993-06-01

101

Temporal binding via cortical coincidence detection of specific and nonspecific thalamocortical inputs: A voltage-dependent dye-imaging study in mouse brain slices  

PubMed Central

Voltage-sensitive dye imaging of mouse thalamocortical slices demonstrated that electrical stimulation of the centrolateral intralaminar thalamic nucleus (CL) resulted in the specific activation of thalamic reticular nucleus, striatum/putamen, and cortical layers 5, 6, and 1. By contrast, ventrobasal (VB) thalamic stimulation, while activating the reticular and basal ganglia nuclei, also activated directly layers 4 and deep 5 of the cortex. Conjoined stimulation of the VB and CL nuclei resulted in supralinear summation of the two inputs at cortical output layer 5, demonstrating coincidence detection along the apical dendrites. This supralinear summation was also noticed at gamma band stimulus frequency (?40 Hz). Direct stimulation of cortical layer 1, after a radial section of the cortex that spared only that layer, was shown to sum supralinearly with the cortical activation triggered by VB stimulation, providing a second demonstration for coincidence detection. Coincidence detection by coactivation of the specific (VB) and nonspecific (CL) thalamic nuclei has been proposed as the basis for the temporal conjunction that supports cognitive binding in the brain.

Llinas, Rodolfo R.; Leznik, Elena; Urbano, Francisco J.

2002-01-01

102

Relationship between LiDAR-derived forest canopy height and Landsat images  

Microsoft Academic Search

The mean and standard deviation (SD) of light detection and ranging (LiDAR)-derived canopy height are related to forest structure. However, LiDAR data typically cover a limited area and have a high economic cost compared with satellite optical imagery. Optical images may be required to extrapolate LiDAR height measurements across a broad landscape. Different spectral indices were obtained from three Landsat

Cristina Pascual; Antonio García-Abril; Warren B. Cohen; Susana Martín-Fernández

2010-01-01

103

Synthesis and biological evaluation of novel radioiodinated imidazopyridine derivatives for amyloid-? imaging in Alzheimer's disease.  

PubMed

Non-invasive detection for amyloid-? peptide (A?) deposition has important significance for the early diagnosis and medical intervention for Alzheimer's disease (AD). In this study, we developed a series of imidazopyridine derivatives as potential imaging agents for single-photon emission computed tomography (SPECT). Two of them, compounds DRK092 and DRM106, showed higher affinity for synthetic human A? 1-40 fibrils than did the well-known amyloid-imaging agent IMPY. A metabolite analysis revealed brain-permeable radioactive metabolites of (125)I-labeled DRK092 and IMPY; no radioactive metabolites from (125)I-labeled DRM106 ([(125)I]DRM106) were detected. In addition, in vitro autoradiography clearly demonstrated specific binding of [(125)I]DRM106 in the hippocampal region of AD enriched with A? plaques. Thus, our results strongly suggested that compound DRM106 can be used as an imaging agent for SPECT to detect A? deposition in AD brain. PMID:24931274

Chen, Chun-Jen; Bando, Kazunori; Ashino, Hiroki; Taguchi, Kazumi; Shiraishi, Hideaki; Fujimoto, Osuke; Kitamura, Chiemi; Matsushima, Satoshi; Fujinaga, Masayuki; Zhang, Ming-Rong; Kasahara, Hiroyuki; Minamizawa, Takao; Jiang, Cheng; Ono, Maiko; Higuchi, Makoto; Suhara, Tetsuya; Yamada, Kazutaka; Ji, Bin

2014-08-01

104

Derivative-based scale invariant image feature detector with error resilience.  

PubMed

We present a novel scale-invariant image feature detection algorithm (D-SIFER) using a newly proposed scale-space optimal 10th-order Gaussian derivative (GDO-10) filter, which reaches the jointly optimal Heisenberg's uncertainty of its impulse response in scale and space simultaneously (i.e., we minimize the maximum of the two moments). The D-SIFER algorithm using this filter leads to an outstanding quality of image feature detection, with a factor of three quality improvement over state-of-the-art scale-invariant feature transform (SIFT) and speeded up robust features (SURF) methods that use the second-order Gaussian derivative filters. To reach low computational complexity, we also present a technique approximating the GDO-10 filters with a fixed-length implementation, which is independent of the scale. The final approximation error remains far below the noise margin, providing constant time, low cost, but nevertheless high-quality feature detection and registration capabilities. D-SIFER is validated on a real-life hyperspectral image registration application, precisely aligning up to hundreds of successive narrowband color images, despite their strong artifacts (blurring, low-light noise) typically occurring in such delicate optical system setups. PMID:24723627

Mainali, Pradip; Lafruit, Gauthier; Tack, Klaas; Van Gool, Luc; Lauwereins, Rudy

2014-05-01

105

A 1000-year sediment record of recurring hypoxia off the Mississippi River: The potential role of terrestrially-derived organic matter inputs  

USGS Publications Warehouse

A suite of inorganic and organic geochemical tracers and a low-oxygen tolerant benthic faunal index ('PEB') were measured in a 14C-dated 2+??m long gravity core collected on the Louisiana shelf adjacent to the Mississippi River delta to study potential millennium-scale low-oxygen events. Periodic down-core excursions in the PEB index throughout the core suggest recurring, natural bottom water low-oxygen events that extend back ??? 1000??14C years. Select trace element and biomarker distributions in these same sediments were examined as potential tracers of past hypoxic events and to help distinguish between marine versus terrestrial processes involved in organic carbon production. In discrete sediment horizons where the PEB index was elevated, redox-sensitive vanadium concentrations were consistently depleted, excursions in sedimentary ??13C suggest periodic, preferential terrestrial inputs, and the concentrations of two sterol biomarkers (sitosterol and ??-stigmasterol) also showed concurrent enrichments. If the PEB index successfully records ??? 1000??14C year-scale low-oxygen events, then the distribution of these geochemical tracers can be interpreted to corroborate the view that naturally occurring low-oxygen bottom water conditions have existed on the inner Louisiana continental shelf, not only in recent times, but also over at least the last 1000??14C years. These data support the general hypothesis that historic, low-oxygen bottom water conditions on the Louisiana shelf are likely tied to periods of increased fluvial discharge and associated wetland export in the absence of modern river levees. Enhanced river discharge and associated material export would both stimulate enhanced in situ organic carbon production and foster water column stratification. Such periodic elevated river flows during the last millennium can be linked to climate fluctuations and tropical storm activity. ?? 2008 Elsevier B.V. All rights reserved.

Swarzenski, P. W.; Campbell, P. L.; Osterman, L. E.; Poore, R. Z.

2008-01-01

106

Derivatives  

NSDL National Science Digital Library

Murray Bourne developed the Interactive Mathematics site while working as a mathematics lecturer at Ngee Ann Polytechnic in Singapore. The site contains numerous mathematics tutorials and resources for students and teachers alike. This specific page is focused on differentiation, or finding derivatives. Bourne walks users through an introduction to differentiation and limits, and then moves on to more specific applications like rate of change, derivatives of polynomials, and differentiating powers of a function. Each topic includes graphs and interactive materials designed to aid users in understanding the presented concepts. The information here is presented in a clear, straightforward manner that is appropriate for introductory and advanced calculus students alike.

Bourne, Murray

2008-04-22

107

An operational software tool for the analysis of coronagraph images: Determining CME parameters for input into the WSA-Enlil heliospheric model  

NASA Astrophysics Data System (ADS)

Coronal mass ejections (CMEs)—massive explosions of dense plasma that originate in the lower solar atmosphere and propagate outward into the solar wind—are the leading cause of significant space weather effects within Earth's environment. Computational models of the heliosphere such as WSA-Enlil offer the possibility of predicting whether a given CME will become geo-effective and, if so, the likely time of arrival at Earth. To be meaningful, such a forecast model is dependent upon accurately characterizing key parameters for the CME, notably its speed and direction of propagation, and its angular width. Studies by Zhao et al. (2002) and Xie et al. (2004) suggest that these key CME parameters can be deduced from geometric analysis of the elliptical "halo" forms observed in coronagraph images on spacecraft such as the Solar and Heliospheric Observatory (SOHO) and which result from a CME whose propagation is roughly toward or away from the observer. Both studies assume that the CME presents a circular cross-section and maintains a constant angular width during its radial expansion, the so called "cone model." Development work at the NOAA Space Weather Prediction Center (SWPC) has been concerned with building and testing software tools to allow forecasters to determine these CME parameters routinely within an operational context, a key aspect of transitioning the WSA-Enlil heliospheric model into operations at the National Weather Service. We find "single viewpoint" cone analysis, while a useful start, to be highly problematic in many real-world situations. In particular, it is extremely difficult to establish objectively the correct ellipse that should be applied to a given halo form and that small changes in the exact ellipse chosen can lead to large differences in the deduced CME parameters. The inaccuracies in the technique are particularly evident for analysis of the "nearly circular" elliptical forms which result from CMEs that are propagating directly toward the observer and are therefore the most likely to be geo-effective. In working to resolve this issue we have developed a new three-dimensional (3-D) graphics-based analysis system which seeks to reduce inaccuracies by analyzing a CME using coronagraph images taken concurrently by SOHO and also by the two Solar TErrestrial RElations Observatory (STEREO) spacecraft, which provide additional viewing locations well away from the Sun-Earth line. The resulting "three view" technique has led to the development of the CME Analysis Tool (CAT), an operational software system in routine use at the SWPC as the primary means to determine CME parameters for input into the WSA-Enlil model. Results from the operational WSA-Enlil system are presented: utilizing CAT to provide CME input parameters, we show that, during the first year of operations at SWPC, the WSA-Enlil model has forecasted the arrival of CMEs at Earth with an average error 7.5 h.

Millward, G.; Biesecker, D.; Pizzo, V.; Koning, C. A.

2013-02-01

108

Corrections of arterial input function for dynamic H215O PET to assess perfusion of pelvic tumours: arterial blood sampling versus image extraction  

NASA Astrophysics Data System (ADS)

Assessment of perfusion with 15O-labelled water (H215O) requires measurement of the arterial input function (AIF). The arterial time activity curve (TAC) measured using the peripheral sampling scheme requires corrections for delay and dispersion. In this study, parametrizations with and without arterial spillover correction for fitting of the tissue curve are evaluated. Additionally, a completely noninvasive method for generation of the AIF from a dynamic positron emission tomography (PET) acquisition is applied to assess perfusion of pelvic tumours. This method uses a volume of interest (VOI) to extract the TAC from the femoral artery. The VOI TAC is corrected for spillover using a separate tissue TAC and for recovery by determining the recovery coefficient on a coregistered CT data set. The techniques were applied in five patients with pelvic tumours who underwent a total of 11 examinations. Delay and dispersion correction of the blood TAC without arterial spillover correction yielded in seven examinations solutions inconsistent with physiology. Correction of arterial spillover increased the fitting accuracy and yielded consistent results in all patients. Generation of an AIF from PET image data was investigated as an alternative to arterial blood sampling and was shown to have an intrinsic potential to determine the AIF noninvasively and reproducibly. The AIF extracted from a VOI in a dynamic PET scan was similar in shape to the blood AIF but yielded significantly higher tissue perfusion values (mean of 104.0 ± 52.0%) and lower partition coefficients (-31.6 ± 24.2%). The perfusion values and partition coefficients determined with the VOI technique have to be corrected in order to compare the results with those of studies using a blood AIF.

Lüdemann, L.; Sreenivasa, G.; Michel, R.; Rosner, C.; Plotkin, M.; Felix, R.; Wust, P.; Amthauer, H.

2006-06-01

109

Reprocessing input data validation  

SciTech Connect

The Isotope Correlation Technique (ICT), in conjunction with the gravimetric (Pu/U ratio) method for mass determination, provides an independent verification of the input accountancy at the dissolver or accountancy stage of the reprocessing plant. The Isotope Correlation Technique has been applied to many classes of domestic and international reactor systems (light-water, heavy-water, graphite, and liquid-metal) operating in a variety of modes (power, research, production, and breeder), and for a variety of reprocessing fuel cycle management strategies. Analysis of reprocessing operations data based on isotopic correlations derived for assemblies in a PWR environment and fuel management scheme, yielded differences between the measurement-derived and ICT-derived plutonium mass determinations of ({minus}0.02 {plus minus} 0.23)% for the measured U-235 and (+0.50 {plus minus} 0.31)% for the measured Pu-239, for a core campaign. The ICT analyses has been implemented for the plutonium isotopics in a depleted uranium assembly in a heavy-water, enriched uranium system and for the uranium isotopes in the fuel assemblies in light-water, highly-enriched systems. 7 refs., 5 figs., 4 tabs.

Persiani, P.J.; Bucher, R.G.; Pond, R.B.; Cornella, R.J.

1990-01-01

110

Fluorinated Benzofuran Derivatives for PET Imaging of ?-Amyloid Plaques in Alzheimer's Disease Brains  

PubMed Central

A series of fluorinated benzofuran derivatives as potential tracers for positron emission tomography (PET) targeting ?-amyloid plaques in the brains of patients with Alzheimer's disease (AD) were synthesized and evaluated. The derivatives were produced using an intramolecular Wittig reaction. In experiments in vitro, all displayed high affinity for A?(1?42) aggregates with Ki values in the nanomolar range. Radiofluorinated 17, [18F]17, in particular labeled ?-amyloid plaques in sections of Tg2576 mouse brain and displayed high uptake (5.66% ID/g) at 10 min postinjection, sufficient for PET imaging. In addition, in vivo ?-amyloid plaque labeling can be clearly demonstrated with [18F]17 in Tg2576 mice. In conclusion, [18F]17 may be useful for detecting ?-amyloid plaques in patients with AD.

2010-01-01

111

Near-infrared-fluorescence imaging of lymph nodes by using liposomally formulated indocyanine green derivatives.  

PubMed

Liposomally formulated indocyanine green (LP-ICG) has drawn much attention as a highly sensitive near-infrared (NIR)-fluorescence probe for tumors or lymph nodes in vivo. We synthesized ICG derivatives tagged with alkyl chains (ICG-Cn), and we examined NIR-fluorescence imaging for lymph nodes in the lower extremities of mice by using liposomally formulated ICG-Cn (LP-ICG-Cn) as well as conventional liposomally formulated ICG (LP-ICG) and ICG. Analysis with a noninvasive preclinical NIR-fluorescence imaging system revealed that LP-ICG-Cn accumulates in only the popliteal lymph node 1h after injection into the footpad, whereas LP-ICG and ICG accumulate in the popliteal lymph node and other organs like the liver. This result indicates that LP-ICG-Cn is a useful NIR-fluorescence probe for noninvasive in vivo bioimaging, especially for the sentinel lymph node. PMID:24393719

Toyota, Taro; Fujito, Hiromichi; Suganami, Akiko; Ouchi, Tomoki; Ooishi, Aki; Aoki, Akira; Onoue, Kazutaka; Muraki, Yutaka; Madono, Tomoyuki; Fujinami, Masanori; Tamura, Yutaka; Hayashi, Hideki

2014-01-15

112

The evaluation of NIR-absorbing porphyrin derivatives as contrast agents in photoacoustic imaging.  

PubMed

Six free base tetrapyrrolic chromophores, three quinoline-annulated porphyrins and three morpholinobacteriochlorins, that absorb light in the near-IR range and possess, in comparison to regular porphyrins, unusually low fluorescence emission and (1)O2 quantum yields were tested with respect to their efficacy as novel molecular photo-acoustic imaging contrast agents in a tissue phantom, providing an up to ?2.5-fold contrast enhancement over that of the benchmark contrast agent ICG. The testing protocol compares the photoacoustic signal output strength upon absorption of approximately the same light energy. Some relationships between photophysical parameters of the dyes and the resulting photoacoustic signal strength could be derived. PMID:24071709

Abuteen, Akram; Zanganeh, Saeid; Akhigbe, Joshua; Samankumara, Lalith P; Aguirre, Andres; Biswal, Nrusingh; Braune, Marcel; Vollertsen, Anke; Röder, Beate; Brückner, Christian; Zhu, Quing

2013-11-14

113

COLLINARUS: collection of image-derived non-linear attributes for registration using splines  

NASA Astrophysics Data System (ADS)

We present a new method for fully automatic non-rigid registration of multimodal imagery, including structural and functional data, that utilizes multiple texutral feature images to drive an automated spline based non-linear image registration procedure. Multimodal image registration is significantly more complicated than registration of images from the same modality or protocol on account of difficulty in quantifying similarity between different structural and functional information, and also due to possible physical deformations resulting from the data acquisition process. The COFEMI technique for feature ensemble selection and combination has been previously demonstrated to improve rigid registration performance over intensity-based MI for images of dissimilar modalities with visible intensity artifacts. Hence, we present here the natural extension of feature ensembles for driving automated non-rigid image registration in our new technique termed Collection of Image-derived Non-linear Attributes for Registration Using Splines (COLLINARUS). Qualitative and quantitative evaluation of the COLLINARUS scheme is performed on several sets of real multimodal prostate images and synthetic multiprotocol brain images. Multimodal (histology and MRI) prostate image registration is performed for 6 clinical data sets comprising a total of 21 groups of in vivo structural (T2-w) MRI, functional dynamic contrast enhanced (DCE) MRI, and ex vivo WMH images with cancer present. Our method determines a non-linear transformation to align WMH with the high resolution in vivo T2-w MRI, followed by mapping of the histopathologic cancer extent onto the T2-w MRI. The cancer extent is then mapped from T2-w MRI onto DCE-MRI using the combined non-rigid and affine transformations determined by the registration. Evaluation of prostate registration is performed by comparison with the 3 time point (3TP) representation of functional DCE data, which provides an independent estimate of cancer extent. The set of synthetic multiprotocol images, acquired from the BrainWeb Simulated Brain Database, comprises 11 pairs of T1-w and proton density (PD) MRI of the brain. Following the application of a known warping to misalign the images, non-rigid registration was then performed to recover the original, correct alignment of each image pair. Quantitative evaluation of brain registration was performed by direct comparison of (1) the recovered deformation field to the applied field and (2) the original undeformed and recovered PD MRI. For each of the data sets, COLLINARUS is compared with the MI-driven counterpart of the B-spline technique. In each of the quantitative experiments, registration accuracy was found to be significantly (p < 0.05) for COLLINARUS compared with MI-driven B-spline registration. Over 11 slices, the mean absolute error in the deformation field recovered by COLLINARUS was found to be 0.8830 mm.

Chappelow, Jonathan; Bloch, B. Nicolas; Rofsky, Neil; Genega, Elizabeth; Lenkinski, Robert; Dewolf, William; Viswanath, Satish; Madabhushi, Anant

2009-02-01

114

Imer-product array processor for retrieval of stored images represented by bipolar binary (+1,-1) pixels using partial input trinary pixels represented by (+1,-1)  

NASA Technical Reports Server (NTRS)

An inner-product array processor is provided with thresholding of the inner product during each iteration to make more significant the inner product employed in estimating a vector to be used as the input vector for the next iteration. While stored vectors and estimated vectors are represented in bipolar binary (1,-1), only those elements of an initial partial input vector that are believed to be common with those of a stored vector are represented in bipolar binary; the remaining elements of a partial input vector are set to 0. This mode of representation, in which the known elements of a partial input vector are in bipolar binary form and the remaining elements are set equal to 0, is referred to as trinary representation. The initial inner products corresponding to the partial input vector will then be equal to the number of known elements. Inner-product thresholding is applied to accelerate convergence and to avoid convergence to a negative input product.

Liu, Hua-Kuang (Inventor); Awwal, Abdul A. S. (Inventor); Karim, Mohammad A. (Inventor)

1993-01-01

115

Vector image method for the derivation of elastostatic solutions for point sources in a plane layered medium. Part 1: Derivation and simple examples  

NASA Technical Reports Server (NTRS)

An image method algorithm is presented for the derivation of elastostatic solutions for point sources in bonded halfspaces assuming the infinite space point source is known. Specific cases were worked out and shown to coincide with well known solutions in the literature.

Fares, Nabil; Li, Victor C.

1986-01-01

116

Apparent Surface Reflectance of the DOE ARM SGP CART Central Site Derived from AVIRIS Spectral Images  

NASA Technical Reports Server (NTRS)

The primary objective of the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) is to acquire in situ and remote sensing data to improve cloud and atmospheric radiative models and parameterizations. As a consequence of this program, a large number of atmosphere and surface measurements are being acquired at the ARM SGP CART central site. NASA's Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) overflew this site on August 1, 1997. AVIRIS measures the upwelling spectral solar radiance from 400 to 2500 nm at 10-nm intervals. From 20 km altitude, these calibrated spectra are acquired as images of 11 by up to 800 km with 20-by-20 m spatial resolution. These data were acquired at the ARM SGP CART Central Site to first investigate derivation of atmospheric parameters from the measured spectra, second study the variation of these parameters, and third demonstrate the inversion of the calibrated radiance spectra to apparent surface reflectance. These objectives have been pursued with AVIRIS data at other sites for atmospheric water vapor and derivation of apparent surface reflectance.

Green, Robert O.

1998-01-01

117

Testing sensitivity of the LISFLOOD subgrid hydraulic model to SAR image derived information  

NASA Astrophysics Data System (ADS)

There has been much interest in the use of Synthetic Aperture Radar (SAR) images to indirectly estimate flood extent and flood elevation to aid the understanding of fluvial flood inundation processes. SAR remote sensing satellites are capable of all-weather day/night observations that can discriminate between land and smooth open water surfaces over large scales. By combining SAR derived information with 2D hydraulic models and terrain data, the mechanisms of flooding can be better simulated therefore enabling more accurate and reliable flood forecasting. The objective of this study is to test the sensitivity of a LISFLOOD subgrid 2D model to its main parameters (i.e. roughness coefficient, river bathymetry) using SAR derived flood extent maps. Because of SAR imaging techniques and processing steps used to derive the flood information, any SAR-derived flood extent image will contain inherent uncertainty. We therefore use the uncertainty of the SAR information to obtain a range of plausible parameters to test sensitivity of the hydraulic model. LISFLOOD is a distributed 2D model developed at the University of Bristol and designed for use with larger ungauged river catchments. The version used employs a subgrid procedure which allows any size of river channel below that of the grid resolution to be represented. This procedure has been shown to improve hydraulic connectivity within the modelled flooded area and thus improve flood prediction for data sparse areas. A hydrodynamic LISFLOOD subgrid model of the River Severn at Tewkesbury covering a domain area of 50x70km and including the confluence with a major tributary (the River Avon) will be utilised. A complete storm hydrograph will be used as inflow to the model to simulate the full flood event. Surveyed cross section and gauged daily flows are also available for the River Severn. Therefore, the model results using variable parameters can be compared against results obtained from ground observations to further analyse the sensitivity of the model. The results will show which parameters the LISFLOOD subgrid model are most sensitive to, for the investigated test case.

Wood, Melissa; Bates, Paul; Neal, Jeff; Hostache, Renaud; Matgen, Patrick; Chini, Marco; Giustarini, Laura

2013-04-01

118

Imagery-derived modulation transfer function and its applications for underwater imaging  

NASA Astrophysics Data System (ADS)

The main challenge working with underwater imagery results from both rapid decay of signals due to absorption, which leads to poor signal to noise returns, and the blurring caused by strong scattering by the water itself and constituents within, especially particulates. The modulation transfer function (MTF) of an optical system gives the detailed and precise information regarding the system behavior. Underwater imageries can be better restored with the knowledge of the system MTF or the point spread function (PSF), the Fourier transformed equivalent, extending the performance range as well as the information retrieval from underwater electro-optical system. This is critical in many civilian and military applications, including target and especially mine detection, search and rescue, and diver visibility. This effort utilizes test imageries obtained by the Laser Underwater Camera Imaging Enhancer (LUCIE) from Defense Research and Development Canada (DRDC), during an April-May 2006 trial experiment in Panama City, Florida. Imaging of a standard resolution chart with various spatial frequencies were taken underwater in a controlled optical environment, at varying distances. In-water optical properties during the experiment were measured, which included the absorption and attenuation coefficients, particle size distribution, and volume scattering function. Resulting images were preprocessed to enhance signal to noise ratio by averaging multiple frames, and to remove uneven illumination at target plane. The MTF of the medium was then derived from measurement of above imageries, subtracting the effect of the camera system. PSFs converted from the measured MTF were then used to restore the blurred imageries by different deconvolution methods. The effects of polarization from source to receiver on resulting MTFs were examined and we demonstrate that matching polarizations do enhance system transfer functions. This approach also shows promise in deriving medium optical properties including absorption and attenuation.

Hou, Weilin; Weidemann, Alan D.; Gray, Deric J.; Fournier, Georges R.

2007-10-01

119

Remote Sensing of Vegetation Senescence and Stress using Derivative Spectroscopy Applied to Hyperspectral Images  

NASA Astrophysics Data System (ADS)

It is well established that senescence and stress affect the shape of the optical reflectance spectrum of vegetation. A prime example is the shift of the red edge inflection point (REIP) to lower wavelength as senescence or stress increases. The red edge refers to the sharp rise in vegetation reflectance between the chlorophyll well in the red (670-680 nm) and the near infrared plateau (~790-1350 nm). The REIP wavelength shift, however, can be subtle and not easily detected with hyperspectral imagers. I explore the use of derivative spectroscopy to enhance the features in the reflectance spectrum. Conventional analysis focuses on the wavelength position of the REIP as a measure of stress. In this paper, I examine the shape of the entire derivative spectrum to characterize the transition from healthy to senescent deciduous vegetation over the summer to autumn transition. While this transition occurs naturally, it causes changes in the reflectance spectrum similar to those changes due to stress such as drought or soil contamination. The experiment (carried out in southern New England) consisted of clipping leaves from maple and oak trees every two to three days from early September through late November and measuring the optical reflectance in the laboratory using an Analytical Spectral Devices (ASD) Field Spectrometer. Reflectance spectra were measured for stacks of leaves using different numbers of leaves in the stack and different backgrounds. The primary data set was measured using four-leaf stacks on a flat black background. The time series of derivative spectra clearly show the shift in the red edge inflection point as a function of date, as expected. In addition, the overall shape of the derivative spectra changes significantly as leaf senescence proceeds. The utility of derivative spectroscopy lay in whether it can be used with remote sensing data recorded by hyperspectral sensors such the NASA-JPL AVIRIS instrument. The lower spectral sampling of current remote sensing instruments (typically 10 nm) degrades the derivative spectrum compared to the 1-nm sampling of the laboratory measurements. Deployment of a new class of HSI instruments, such as NEON's airborne sensor, will go a long way to alleviating this problem. Different sampling rates were tested by resampling the derivative spectra time series. In general, current instruments with 10-nm sampling are barely adequate for this kind of analysis, with 5-nm sampling providing a significant improvement.

Cipar, J. J.

2012-12-01

120

Thermally activated delayed fluorescence of fluorescein derivative for time-resolved and confocal fluorescence imaging.  

PubMed

Compared with fluorescence imaging utilizing fluorophores whose lifetimes are in the order of nanoseconds, time-resolved fluorescence microscopy has more advantages in monitoring target fluorescence. In this work, compound DCF-MPYM, which is based on a fluorescein derivative, showed long-lived luminescence (22.11 ?s in deaerated ethanol) and was used in time-resolved fluorescence imaging in living cells. Both nanosecond time-resolved transient difference absorption spectra and time-correlated single-photon counting (TCSPC) were employed to explain the long lifetime of the compound, which is rare in pure organic fluorophores without rare earth metals and heavy atoms. A mechanism of thermally activated delayed fluorescence (TADF) that considers the long wavelength fluorescence, large Stokes shift, and long-lived triplet state of DCF-MPYM was proposed. The energy gap (?EST) of DCF-MPYM between the singlet and triplet state was determined to be 28.36 meV by the decay rate of DF as a function of temperature. The ?EST was small enough to allow efficient intersystem crossing (ISC) and reverse ISC, leading to efficient TADF at room temperature. The straightforward synthesis of DCF-MPYM and wide availability of its starting materials contribute to the excellent potential of the compound to replace luminescent lanthanide complexes in future time-resolved imaging technologies. PMID:24936960

Xiong, Xiaoqing; Song, Fengling; Wang, Jingyun; Zhang, Yukang; Xue, Yingying; Sun, Liangliang; Jiang, Na; Gao, Pan; Tian, Lu; Peng, Xiaojun

2014-07-01

121

Synthesis and evaluation of two novel 2-nitroimidazole derivatives as potential PET radioligands for tumor imaging  

PubMed Central

Introduction Nitroimidazole (azomycin) derivatives labeled with radioisotopes have been developed as cancer imaging and radiotherapeutic agents based on the oncological hypoxic mechanism. By attaching nitroimidazole core with different functional groups, we synthesized new nitroimidazole derivatives, and evaluated their potentiality as tumor imaging agents. Methods Starting with commercially available 2-nitroimdazole, 2-fluoro-N-(2-(2-nitro-1H-imidazol-1-yl)ethyl)acetamide (NEFA, [19F]7) and 2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl 2-fluoroacetate (NEFT, [19F]8), as well as radiolabeling precursors - the bromo substituted analogs were quickly synthesized through a three-step synthetic pathway. The precursors were radiolabeled with [18F]F-/18-crown-6/KHCO3 in DMSO at 90 °C for 10 min followed by purification with an Oasis HLB cartridge. Biodistribution studies were carried out in EMT-6 tumor-bearing mice. The uptake (%ID/g) in tumors and normal tissues were measured at 30 min post injection. Liquid chromatography-electrospray ionization mass spectrometry (LC/MS) was used to distinguish metabolites from parent drugs in urine and plasma of rat injected with “cold” NEFA ([19F]7) and NEFT ([19F]8). Results Two radiotracers, [18F]NEFA ([18F]7) and [18F]NEFT ([18F]8), were prepared with average yields of 6-7% and 9-10% (no decay corrected). Radiochemical purity for both tracers was >95% as determined by HPLC. Biodistribution studies in EMT-6 tumor-bearing mice indicated that the tumor to blood and tumor to liver ratios of both [18F]7 (0.96, 0.98) and [18F]8 (0.61,1.10) at 30 min were higher than those observed for [18F]FMISO (1) (0.91, 0.59), a well-investigated azomycin type hypoxia radiotacer. LC/MS analysis demonstrated that fluoroacetate was the main in vivo metabolite for both NEFA ([19F]7) and NEFT ([19F]8). Conclusions In this research, two new fluorine-18 labeled 2-nitroimdazole derivatives, [18F]7 and [18F]8, both of which containing in vivo hydrolyzable group, were successfully prepared. Further biological evaluations are warranted to investigate their potential as PET radioligands for imaging tumor.

Zha, Zhihao; Zhu, Lin; Liu, Yajing; Du, Fenghua; Gan, Hongmei; Qiao, Jinpin; Kung, Hank F.

2011-01-01

122

Desorption kinetics from a surface derived from direct imaging of the adsorbate layer.  

PubMed

There are numerous indications that adsorbed particles on a surface do not desorb statistically, but that their spatial distribution is important. Evidence almost exclusively comes from temperature-programmed desorption, the standard method for measuring desorption rates. However, this method, as a kinetics experiment, cannot uniquely prove an atomic mechanism. Here we report a low-energy electron microscopy investigation in which a surface is microscopically imaged while simultaneously temperature-programmed desorption is recorded. The data show that during desorption of oxygen molecules from a silver single crystal surface, islands of oxygen atoms are present. By correlating the microscopy and the kinetics data, a model is derived that includes the shapes of the islands and assumes that the oxygen molecules desorb from the island edges. The model quantitatively reproduces the complex desorption kinetics, confirming that desorption is affected by islands and that the often used mean-field treatment is inappropriate. PMID:24834863

Günther, S; Mente?, T O; Niño, M A; Locatelli, A; Böcklein, S; Wintterlin, J

2014-01-01

123

Desorption kinetics from a surface derived from direct imaging of the adsorbate layer  

NASA Astrophysics Data System (ADS)

There are numerous indications that adsorbed particles on a surface do not desorb statistically, but that their spatial distribution is important. Evidence almost exclusively comes from temperature-programmed desorption, the standard method for measuring desorption rates. However, this method, as a kinetics experiment, cannot uniquely prove an atomic mechanism. Here we report a low-energy electron microscopy investigation in which a surface is microscopically imaged while simultaneously temperature-programmed desorption is recorded. The data show that during desorption of oxygen molecules from a silver single crystal surface, islands of oxygen atoms are present. By correlating the microscopy and the kinetics data, a model is derived that includes the shapes of the islands and assumes that the oxygen molecules desorb from the island edges. The model quantitatively reproduces the complex desorption kinetics, confirming that desorption is affected by islands and that the often used mean-field treatment is inappropriate.

Günther, S.; Mente?, T. O.; Niño, M. A.; Locatelli, A.; Böcklein, S.; Wintterlin, J.

2014-05-01

124

Plasma distribution in Mercury's magnetosphere derived from MESSENGER Magnetometer and Fast Imaging Plasma Spectrometer observations  

NASA Astrophysics Data System (ADS)

assess the statistical spatial distribution of plasma in Mercury's magnetosphere from observations of magnetic pressure deficits and plasma characteristics by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. The statistical distributions of proton flux and pressure were derived from 10 months of Fast Imaging Plasma Spectrometer (FIPS) observations obtained during the orbital phase of the MESSENGER mission. The Magnetometer-derived pressure distributions compare favorably with those deduced from the FIPS observations at locations where depressions in the magnetic field associated with the presence of enhanced plasma pressures are discernible in the Magnetometer data. The magnitudes of the magnetic pressure deficit and the plasma pressure agree on average, although the two measures of plasma pressure may deviate for individual events by as much as a factor of ~3. The FIPS distributions provide better statistics in regions where the plasma is more tenuous and reveal an enhanced plasma population near the magnetopause flanks resulting from direct entry of magnetosheath plasma into the low-latitude boundary layer of the magnetosphere. The plasma observations also exhibit a pronounced north-south asymmetry on the nightside, with markedly lower fluxes at low altitudes in the northern hemisphere than at higher altitudes in the south on the same field line. This asymmetry is consistent with particle loss to the southern hemisphere surface during bounce motion in Mercury's offset dipole magnetic field.

Korth, Haje; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Solomon, Sean C.; McNutt, Ralph L.

2014-04-01

125

Preparation of asymmetric urea derivatives that target prostate-specific membrane antigen for SPECT imaging.  

PubMed

Prostate-specific membrane antigen (PSMA) has been identified as a diagnostic and therapeutic target for prostate cancer. (S)-2-[3-[(R)-1-Carboxy-2-mercaptoethyl]ureido-pentanedioic acid (Cys-CO-Glu) were used to design novel PSMA targeting probes by nucleophilic conjugate addition between cysteine and maleimide based reagents. 3 ([(123)I]IGLCE) was synthesized by this strategy and showed high affinity for PSMA. Results of binding inhibition assays of these derivatives suggested the importance of an aromatic group and succinimide moiety for high affinity. [(123)I]3 was evaluated in vivo with PSMA positive LNCaP and PSMA negative PC-3 human prostate cancer xenograft bearing mice. [(125)I]3 accumulated in LNCaP tumors but not in PC-3 tumors, and the accumulation was inhibited by 2-(phosphonomethyl)pentanedioic acid (2-PMPA). Use of [(123)I]3 provided positive images of LNCaP tumors in single photon emission tomography scans. These results warrant further evaluation of [(123)I]3 and its derivatives as radiolabeled probes for the diagnosis of prostate cancer. PMID:24063417

Harada, Naoya; Kimura, Hiroyuki; Ono, Masahiro; Saji, Hideo

2013-10-24

126

Derived Image of the Rupture Process of the Great Earthquakes Using Processing of Dense Arrays  

NASA Astrophysics Data System (ADS)

The study of the source of major earthquakes is of great interest for the scientific community because the parameters derived from have a major importance for the rapid estimation of associated effects (destruction or tsunami). The back-projection technics allow to follow the rupture process in space and in time. In the framework of these studies, we have identified the array processing as a modern tool that can provide important information concerning the geometry and the kinematics of the rupture. Thanks to the various technologies implied in the CTBT, we have brought these studies in the field of seismology, infrasound and hydroacoustic. These different approaches have resulted in either a direct visualization of the rupture thanks to the analysis of variations of azimuth with time of direct waves from the source or indirectly by obtaining the scope of radiation pattern of surface waves. This type of image is innovative because it allows provide information on geographic areas which are not instrumented. We show multiple images of PMCC processing (Progressive Multi Channel Correlation) associated with different major earthquakes as Sumatra Mw=9.3, Nias Mw=8.7, Kokoxoli Mw=7.8, Tohoku Mw=9.0 and how we can constrain the rupture of these events. These studies show the interest of the CTBT network and more precisely the dense arrays of sensors. These arrays offer the unique opportunity for a multi-technological approach of the seismic source and, perhaps, ultimately, the improvement of warning systems.

Guilbert, J.; Le Pichon, A.; Sèbe, O.; Vergoz, J.

2012-12-01

127

Optical Imaging of Tumors with Copper-Labeled Rhodamine Derivatives by Targeting Mitochondria  

PubMed Central

In this study, we evaluated Cu(L1) in two xenografted tumor-bearing (U87MG and MDA-MB-435) animal models to prove the concept that Cu(II)-labeled rhodamine derivatives, Cu(L) (L = L1 - L4) are useful as selective fluorescent probes for tumor imaging. We found that both multidrug resistance (MDR) negative U87MG gliomas and MDR-positive MDA-MB-435 breast tumors could be visualized. Because of tissue attenuation, accurate quantification of tumor uptake was difficult by optical methods. Therefore, 64Cu(L) (L = L1 - L4) were evaluated to compare their biodistribution properties. It was found that all four 64Cu radiotracers had a high glioma uptake (64Cu(L1): 5.71± 1.43 %ID/g; 64Cu(L2): 5.98 ± 2.75 %ID/g; 64Cu(L3): 4.28 ± 1.45 %ID/g; and 64Cu(L4): 6.25 ± 3.42 %ID/g) with 64Cu(L1) showing the highest tumor/background ratios. In athymic nude mice bearing MDA-MB-435 breast cancer xenografts, 64Cu(L4) showed almost identical normal organ uptake to that in the glioma-bearing animals, but its breast tumor uptake (1.26 ± 0.10% ID/g) was significantly lower (p < 0.001) than that in the glioma (6.25 ± 3.42% ID/g) because of MDR Pgps (P-glycoproteins) and MRPs (multidrug resistance-associated proteins) overexpressed in the xenografted MDA-MB-435 breast tumors. Results from cellular staining assays showed that both Cu(L2) and Cu(L4) were able to localize in mitochondria of U87MG cells, and their tumor selectivity was caused by the elevated negative mitochondrial potential in U87MG glioma cells as compared to that in human fibroblast cells. On the basis of these results, it was concluded that Cu(L) (L = L1 - L4) are useful as selective fluorescent probes for cellular staining assays and optical tumor imaging while 64Cu(L) (L = L1 - L4) have the potential as PET radiotracers for tumor imaging. This study represents a good example of dual modality imaging (PET and optical) using two agents, 64Cu(L) and Cu(L), with identical chemical composition. Future research will focus on developing new fluorescent probes with longer wavelength and reduced liver uptake.

Yan, Xin; Zhou, Yang; Liu, Shuang

2012-01-01

128

Bioluminescent imaging demonstrates transplanted human embryonic stem cell-derived CD34+ cells preferentially develop into endothelial cells  

PubMed Central

Human embryonic stem cells (hESCs) provide an important resource for novel regenerative medicine therapies and have been used to derive diverse cell populations, including hematopoietic and endothelial cells. However, it remains a challenge to achieve significant engraftment of hESC-derived blood cells when transplanted into animal models. To better understand mechanisms that enhance or limit the in vivo developmental potential of hESC-derived cells, we utilized hESCs that express firefly luciferase (luc) to allow non-invasive, real-time bioluminescent imaging of hESC-derived CD34+ cells transplanted into the liver of neonatal immunodeficient mice. Serial imaging demonstrated stable engraftment and expansion of the luc+ hESC-derived cells in vivo over several months. While we found that these hESC-derived CD34+ cells have bipotential ability to generate both hematopoietic and endothelial lineages in vitro, these studies demonstrate preferential differentiation into endothelial cells in vivo, with only low levels of hematopoietic cell engraftment. Therefore, these studies reveal key differences in the developmental potential of hESC-derived cells using in vitro and in vivo analyses. While transplanted hESC-derived CD34+ cells are well suited for revascularization therapies, additional measures are needed to provide higher levels of long-term hematopoietic engraftment.

Tian, Xinghui; Hexum, Melinda K.; Penchev, Vesselin R.; Taylor, Russell J.; Shultz, Leonard D.; Kaufman, Dan S

2010-01-01

129

Input devices for CCDs  

NASA Astrophysics Data System (ADS)

A systematic account of the physical and network-engineering aspects of the operation and design of input devices for CCDs is presented with emphasis on the maximum possibilities of such devices with respect to the injection of small signals into the CCD. A classification of input devices is given. It is shown that a unified approach to input devices as devices that are based on transistor structures makes it possible to identify the properties and limitations of all types of input devices for CCDs. Particular consideration is given to potentials and charges of MOS cells, methods of signal injection, the concentration of charge carriers in the source and gate, and the volt-ampere characteristics of input devices. Equivalent circuits, modes of operation, and electric circuits of input devices are also considered

Trishenkov, M. A.; Vinetskii, Iu. R.

1982-12-01

130

Processing distributed inputs in coupled excitable lasers  

SciTech Connect

In many instances, networks of dynamical elements are subject to distributed input signals that enter the network through different nodes. In these cases, processing of the input signals may be mediated by coupling, in what constitutes an emerging property of the network. Here we study experimentally this effect in two mutually injected semiconductor lasers with optical feedback, operating in an excitable regime. The lasers are subject to different periodic input signals in their pump current, with distinct frequencies. Our results show that when the signals are harmonics of an absent fundamental, the laser array is able to process these signals and respond at the missing fundamental frequency. When the input frequencies are rigidly shifted from their harmonic values, the response frequency follows a simple law derived from a linear sum of the inputs, even though the array integrates the electrical inputs after having transduced them optically. The results are reproduced numerically with a dynamical model of the laser array.

Gonzalez, Cristina M.; Torrent, M. C.; Garcia-Ojalvo, Jordi [Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Colom 11, E-08222 Terrassa (Spain); Buldu, Javier M. [Nonlinear Dynamics and Chaos Group, Departamento de Fisica, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain)

2007-11-15

131

COLLINARUS: collection of image-derived non-linear attributes for registration using splines  

Microsoft Academic Search

We present a new method for fully automatic non-rigid registration of multimodal imagery, including structural and functional data, that utilizes multiple texutral feature images to drive an automated spline based non-linear image registration procedure. Multimodal image registration is significantly more complicated than registration of images from the same modality or protocol on account of difficulty in quantifying similarity between different

Jonathan Chappelow; B. Nicolas Bloch; Neil Rofsky; Elizabeth Genega; Robert Lenkinski; William Dewolf; Satish Viswanath; Anant Madabhushi

2009-01-01

132

Ray-space based 3D image input method for a color 3D display using a method of the (a) reconstruction of parallax rays  

Microsoft Academic Search

We have developed a real-time color autostereoscopic display system using a reconstruction method of parallax rays. The notable point is to be able to display a volumetric image such as holography. Moreover, the data of this system can reduce much than that of hologram. Also, this system is visible to multiple viewers at the same time without special glasses. Well-known

Hideya Takahashi; Kenji Yamada; Shimizu Eiji

2002-01-01

133

A Mechanically Derived Systolic Implementation of Pyramid Initialization  

Microsoft Academic Search

Pyramidal algorithms manipulate hierarchical representations of data and are used in many image processing applications, for example, image segmentation and border extraction. We present a systolic network which performs the first phase of pyramidal algorithms: initialization. The derivation of the systolic solution is governed by a mechanical method whose input is a known Pascal-like pyramidal algorithm. After a few manual

Christian Lengauer; Bikash Sabata; Farshid Arman

1989-01-01

134

Mapping and monitoring changes in vegetation communities of Jasper Ridge, CA, using spectral fractions derived from AVIRIS images  

NASA Technical Reports Server (NTRS)

An important application of remote sensing is to map and monitor changes over large areas of the land surface. This is particularly significant with the current interest in monitoring vegetation communities. Most of traditional methods for mapping different types of plant communities are based upon statistical classification techniques (i.e., parallel piped, nearest-neighbor, etc.) applied to uncalibrated multispectral data. Classes from these techniques are typically difficult to interpret (particularly to a field ecologist/botanist). Also, classes derived for one image can be very different from those derived from another image of the same area, making interpretation of observed temporal changes nearly impossible. More recently, neural networks have been applied to classification. Neural network classification, based upon spectral matching, is weak in dealing with spectral mixtures (a condition prevalent in images of natural surfaces). Another approach to mapping vegetation communities is based on spectral mixture analysis, which can provide a consistent framework for image interpretation. Roberts et al. (1990) mapped vegetation using the band residuals from a simple mixing model (the same spectral endmembers applied to all image pixels). Sabol et al. (1992b) and Roberts et al. (1992) used different methods to apply the most appropriate spectral endmembers to each image pixel, thereby allowing mapping of vegetation based upon the the different endmember spectra. In this paper, we describe a new approach to classification of vegetation communities based upon the spectra fractions derived from spectral mixture analysis. This approach was applied to three 1992 AVIRIS images of Jasper Ridge, California to observe seasonal changes in surface composition.

Sabol, Donald E., Jr.; Roberts, Dar A.; Adams, John B.; Smith, Milton O.

1993-01-01

135

Shadow effects in simulated ultrasound images derived from computed tomography images using a focused beam tracing model.  

PubMed

Simulation of ultrasound images based on computed tomography (CT) data has previously been performed with different approaches. Shadow effects are normally pronounced in ultrasound images, so they should be included in the simulation. In this study, a method to capture the shadow effects has been developed, which makes the simulated ultrasound images appear more realistic. The method using a focused beam tracing model gives diffuse shadows that are similar to the ones observed in measurements on real objects. Ultrasound images of a cod (Gadus morhua) were obtained with a BK Medical 2202 ProFocus ultrasound scanner (BK Medical, Herlev, Denmark) equipped with a dedicated research interface giving access to beamformed radio frequency data. CT images were obtained with an Aquilion ONE Toshiba CT scanner (Toshiba Medical Systems Corp., Tochigi, Japan). CT data were mapped from Hounsfield units to backscatter strength, attenuation coefficients, and characteristic acoustic impedance. The focused beam tracing model was used to create maps of the transmission coefficient and scattering strength maps. Field II was then used to simulate an ultrasound image of 38.9 × 55.3 × 4.5 mm, using 10(6) point scatterers. As there is no quantitative method to assess quality of a simulated ultrasound image compared to a measured one, visual inspection was used for evaluation. PMID:22779495

Pham, An Hoai; Lundgren, Bo; Stage, Bjarne; Møller Pedersen, Mads; Bachmann Nielsen, Michael; Hemmsen, Martin Christian; Arendt Jensen, Jørgen

2012-07-01

136

Input Optics System  

NASA Astrophysics Data System (ADS)

In the gravitational waves interferometric detectors, the properties of the light beam at the input of the interferometer are very different from the ones of a standard laser source. Therefore, an interface between the laser source and the interferometer is essential. In this chapter, the interface devoted to deliver a light beam characterized by the right properties is described. This interface is called Input Optics System. The Input Optics System of Advanced Virgo is considered and taken as example: all the subsystems are described, focusing on the involved physical phenomena. Some possible future upgrades are also introduced. At the end, the few differences between the Advanced Virgo and the Advanced Ligo Input Optics Systems are presented.

Tacca, Matteo

137

Input-Output Experiment.  

National Technical Information Service (NTIS)

The objective of the suggested Input-Output experiment was to determine the feasibility of using auroral phenomena to simulate the ionizing effects produced by high-altitude nuclear detonations. Present objectives are focused primarily on the measurement ...

R. E. Meyerott

1964-01-01

138

3T Dynamic Contrast Enhanced Magnetic Resonance Imaging in Prostate Cancer -- Comparison between Population-Averaged and Patient Specific Arterial Input Function  

NASA Astrophysics Data System (ADS)

A population-averaged bi-exponential Arterial Input Function (AIF) has been commonly used to fit Dynamic Contrast Enhanced (DCE) MRI data to pharmacokinetic models. It has also been shown that patient specific AIF improves fit of prostate DCE MRI data to an adiabatic approximation model. In this pilot study, we compared the quality of fit of prostate DCE MRI data (acquired at 3T from two patients) to extended Kety model using the population-averaged AIF and patient specific AIF. Physiological parameters (K^trans--volume transfer constant, ve--extra-cellular extra-vascular space and vp--blood plasma volume) were calculated from tumor, peripheral zone and central gland of prostate. By comparing ?^2 of the fit with the two AIFs of a high enhancing voxel, we conclude that patient specific AIF provides more accurate pharmacokinetic modeling of prostate DCE MRI data in high enhancing areas than population-averaged AIF, thus patient specific AIF may result in more accurate detection of prostatic carcinoma.

Meng, Ran; Maedler, Burkhard; Chang, Silvia; Jones, Edward; Goldenberg, Larry; Kozlowski, Piotr

2009-05-01

139

Post-hoc derivation of SOHO Michelson doppler imager flat fields  

NASA Astrophysics Data System (ADS)

Context: The SOHO satellite now offers a unique perspective on the Sun as it is the only space-based instrument that can provide large, high-resolution data sets over an entire 11-year solar cycle. This unique property enables detailed studies of long-term variations in the Sun. One significant problem when looking for such changes is determining what component of any variation is due to deterioration of the instrument and what is due to the Sun itself. One of the key parameters that changes over time is the apparent sensitivity of individual pixels in the CCD array. This can change considerably as a result of optics damage, radiation damage, and aging of the sensor itself. In addition to reducing the sensitivity of the telescope over time, this damage significantly changes the uniformity of the flat field of the instrument, a property that is very hard to recalibrate in space. For procedures such as feature tracking and intensity analysis, this can cause significant errors. Aims: We present a method for deriving high-precision flat fields for high-resolution MDI continuum data, using analysis of existing continuum and magnetogram data sets. Methods: A flat field is constructed using a large set (1000-4000 frames) of cospatial magnetogram and continuum data. The magnetogram data is used to identify and mask out magnetically active regions on the continuum data, allowing systematic biases to be avoided. This flat field can then be used to correct individual continuum images from a similar time. Results: This method allows us to reduce the residual flat field error by around a factor 6-30, depending on the area considered, enough to significantly change the results from correlation-tracking analysis. One significant advantage of this method is that it can be done retrospectively using archived data, without requiring any special satellite operations.

Potts, H. E.; Diver, D. A.

2008-12-01

140

Imaged substellar companions: not as eccentric as they appear? The effect of an unseen inner mass on derived orbits  

NASA Astrophysics Data System (ADS)

Increasing numbers of substellar companions are now being discovered via direct imaging. Orbital elements for some of these objects have been derived using star-companion astrometry, and several of these appear to have eccentricities significantly greater than zero. We show that stellar motion caused by an undetected inner body may result in the companion elements derived in such a way being incorrect, which could lead to an overestimation of the eccentricity. The magnitude of this effect is quantified in several regimes and we derive the maximum eccentricity error a third body could introduce in a general form, which may be easily applied to any imaged system. Criteria for identifying systems potentially susceptible to this scenario are presented, and we find that around half of the planets/companion brown dwarfs currently imaged could be liable to these errors when their orbital elements are derived. In particular, this effect could be relevant for systems within 100 pc with companions at >50 au, if they also harbour an unseen ˜10 MJ object at >10 au. We use the Fomalhaut system as an example and show that a 10 per cent error could be induced on the planet's eccentricity by an observationally allowed inner mass, which is similar in size to the current error from astrometry.

Pearce, Tim D.; Wyatt, Mark C.; Kennedy, Grant M.

2014-01-01

141

An Analysis of Whole Body Tracer Kinetics in Dynamic PET Studies With Application to Image-Based Blood Input Function Extraction.  

PubMed

In a positron emission tomography (PET) study, the local uptake of the tracer is dependent on vascular delivery and retention. For dynamic studies the measured uptake time-course information can be best interpreted when knowledge of the time-course of tracer in the blood is available. This is certainly true for the most established tracers such as (18)F-Fluorodeoxyglucose (FDG) and (15)O-Water (H 2O). Since direct sampling of blood as part of PET studies is increasingly impractical, there is ongoing interest in image-extraction of blood time-course information. But analysis of PET-measured blood pool signals is complicated because they will typically involve a combination of arterial, venous and tissue information. Thus, a careful appreciation of these components is needed to interpret the available data. To facilitate this process, we propose a novel Markov chain model for representation of the circulation of a tracer atom in the body. The model represents both arterial and venous time-course patterns. Under reasonable conditions equilibration of tracer activity in arterial and venous blood is achieved by the end of the PET study-consistent with empirical measurement. Statistical inference for Markov model parameters is a challenge. A penalized nonlinear least squares process, incorporating a generalized cross-validation score, is proposed. Random effects analysis is used to adaptively specify the structure of the penalty function based on historical samples of directly measured blood data. A collection of arterially sampled data from PET studies with FDG and H 2 O is used to illustrate the methodology. These data analyses are highly supportive of the overall modeling approach. An adaptation of the model to the problem of extraction of arterial blood signals from imaging data is also developed and promising preliminary results for cerebral and thoracic imaging studies with FDG and H 2 O are obtained. PMID:24770914

Huang, Jian; O'Sullivan, Finbarr

2014-05-01

142

The method Heliosat-2 for deriving shortwave solar radiation from satellite images  

Microsoft Academic Search

This article presents the method Heliosat-2 that converts observations made by geostationary meteorological satellites into estimates of the global irradiation at ground level. This new version integrates the knowledge gained by various exploitations of the original method Heliosat and its varieties in a coherent and thorough way. It is based upon the same physical principles but the inputs to the

C. Rigollier; M. Lefevre; L. Wald

2004-01-01

143

Synthesis and preliminary evaluation of novel (99m)Tc-labeled folate derivative via click reaction for SPECT imaging.  

PubMed

The folate receptor is over expressed in a wide variety of human tumors. In this study, a novel (99m)Tc-labeled folate derivative ((99m)Tc-HYNIC-T-FA) was synthesized as a potential FR-targeting imaging probe and its efficiency was evaluated. This (99m)Tc-complex could be obtained through practical manner and showed improved in vivo characteristics compared with other radiofolates. Thus, this novel (99m)Tc-HYNIC-T-FA compound could serve as a potential imaging agent for folate receptor positive tumors. PMID:24880914

Guo, Zhide; Zhang, Pu; Song, Manli; Wu, Xiaowei; Liu, Chang; Zhao, Zuoquan; Lu, Jie; Zhang, Xianzhong

2014-09-01

144

Natural-color and color-infrared image mosaics of the Colorado River corridor in Arizona derived from the May 2009 airborne image collection  

USGS Publications Warehouse

The Grand Canyon Monitoring and Research Center (GCMRC) of the U.S. Geological Survey (USGS) periodically collects airborne image data for the Colorado River corridor within Arizona (fig. 1) to allow scientists to study the impacts of Glen Canyon Dam water release on the corridor’s natural and cultural resources. These data are collected from just above Glen Canyon Dam (in Lake Powell) down to the entrance of Lake Mead, for a total distance of 450 kilometers (km) and within a 500-meter (m) swath centered on the river’s mainstem and its seven main tributaries (fig. 1). The most recent airborne data collection in 2009 acquired image data in four wavelength bands (blue, green, red, and near infrared) at a spatial resolution of 20 centimeters (cm). The image collection used the latest model of the Leica ADS40 airborne digital sensor (the SH52), which uses a single optic for all four bands and collects and stores band radiance in 12-bits. Davis (2012) reported on the performance of the SH52 sensor and on the processing steps required to produce the nearly flawless four-band image mosaic (sectioned into map tiles) for the river corridor. The final image mosaic has a total of only 3 km of surface defects in addition to some areas of cloud shadow because of persistent inclement weather during data collection. The 2009 four-band image mosaic is perhaps the best image dataset that exists for the entire Arizona part of the Colorado River. Some analyses of these image mosaics do not require the full 12-bit dynamic range or all four bands of the calibrated image database, in which atmospheric scattering (or haze) had not been removed from the four bands. To provide scientists and the general public with image products that are more useful for visual interpretation, the 12-bit image data were converted to 8-bit natural-color and color-infrared images, which also removed atmospheric scattering within each wavelength-band image. The conversion required an evaluation of the histograms of each band’s digital-number population within each map tile throughout the corridor and the determination of the digital numbers corresponding to the lower and upper one percent of the picture-element population within each map tile. Visual examination of the image tiles that were given a 1-percent stretch (whereby the lower 1- percent 12-bit digital number is assigned an 8-bit value of zero and the upper 1-percent 12-bit digital number is assigned an 8-bit value of 255) indicated that this stretch sufficiently removed atmospheric scattering, which provided improved image clarity and true natural colors for all surface materials. The lower and upper 1-percent, 12-bit digital numbers for each wavelength-band image in the image tiles exhibit erratic variations along the river corridor; the variations exhibited similar trends in both the lower and upper 1-percent digital numbers for all four wavelength-band images (figs. 2–5). The erratic variations are attributed to (1) daily variations in atmospheric water-vapor content due to monsoonal storms, (2) variations in channel water color due to variable sediment input from tributaries, and (3) variations in the amount of topographic shadows within each image tile, in which reflectance is dominated by atmospheric scattering. To make the surface colors of the stretched, 8-bit images consistent among adjacent image tiles, it was necessary to average both the lower and upper 1-percent digital values for each wavelength-band image over 20 river miles to subdue the erratic variations. The average lower and upper 1-percent digital numbers for each image tile (figs. 2–5) were used to convert the 12-bit image values to 8-bit values and the resulting 8-bit four-band images were stored as natural-color (red, green, and blue wavelength bands) and color-infrared (near-infrared, red, and green wavelength bands) images in embedded geotiff format, which can be read and used by most geographic information system (GIS) and image-processing software. The tiff world files (tfw) are provided, even though they are generally

Davis, Philip A.

2013-01-01

145

Improved High Resolution Controlled Enceladus Atlas derived from Cassini-ISS Images  

NASA Astrophysics Data System (ADS)

The Cassini Imaging Science Subsystem (ISS) acquired 684 high-resolution images (< 1 km/pixel) of Enceladus during its tour through the Saturnian system since 2004. We have combined these images with lower-resolution Cassini images to produce a new high-resolution global controlled mosaic of this moonf Enceladus. This global mosaic is the baseline for the highresolution Enceladus atlas that consists of 15 tiles mapped at a scale of 1:500,000. The nomenclature used in this atlas was proposed by the Cassini imaging team and was approved by the International Astronomical Union (IAU). The whole atlas is available to the public through the Imaging Team's website [http://ciclops.org/maps].

Roatsch, T.; Kersten, E.; Hoffmeister, A.; Matz, K.-D.; Preusker, F.; Porco, C. C.

2012-09-01

146

Empirical electron density models for the inner magnetosphere derived from IMAGE RPI observations  

NASA Astrophysics Data System (ADS)

The radio plasma imager (RPI) onboard NASA's IMAGE satellite measured the electron density distribution in the inner magnetosphere using radio sounding techniques during almost six years from 2000 to 2005. RPI transmitted RF pulses and measured the echo delay times of signals reflected at the respective plasma cutoff frequencies, stepping through the frequency range from 3 to 3000 kHz. The echo traces in the plasmagrams of signals that propagated along magnetic field lines were inverted into electron density profiles along the field line. In contrast to previous in situ measurements which had to do a statistical composition of profiles, the entire RPI profile is obtained from one plasmagram recorded in less than a minute. Empirical models of the electron density distribution in the plasmasphere and the polar cap region were developed from the ensemble of profiles describing the plasma distribution. Nearly 1000 profiles were analyzed for the plasmasphere, and close to 2000 in the polar cap. For the polar cap our study covers a geocentric distance of R from 1.4 to 5.0 RE, where the polar cap is defined by an empirical boundary model that takes into account the dynamic nature of the location and size of the polar cap. The RPI Ne data show that the electron density distribution in the polar cap depends on the geocentric distance, R, geomagnetic activity level as measured by the Kp index, and solar illumination (solar zenith angle) at the footprints of the geomagnetic field lines. Our analysis of polar cap Ne data shows that although an increase in geomagnetic activity leads to an enhanced Ne, the enhancement is found to be altitude dependent such that the enhancement in Ne is most pronounced at higher altitudes. At geocentric distance of 4.5 RE, an increase in the geomagnetic activity level from Kp smaller than 2 to 5 results in an Ne increase by a factor of 5. On the other hand, the observations show a strong solar illumination control of Ne at lower altitudes, and not at higher. RPI Ne data show that in the polar cap at geocentric distance of about 2 RE, the average Ne is larger on the sunlit side than on the dark side by a factor of 3 - 4 both for quiet and disturbed conditions. At a geocentric distance of 2.5 RE the effects of these two factors on Ne appear to be comparable. Similar to previous polar cap density models, the new empirical model of Ne developed in this study takes the form of a power law. While in the previous Ne functional representations the power index is a constant, the power index in our representation of Ne distribution is a function of Kp index and solar zenith angle, which itself is dependent on latitude and local time In the plasmasphere, the data coverage is not very extensive but it is sufficient to describe the latitudinal variations. A hemispheric asymmetry was observed with higher densities in the winter hemisphere during solstices. Attempts have been made to connect the plasmasphere models to the topside ionospheric models derived from ISIS topside sounder data using Vary-Chap representations.

Reinisch, B. W.; Nsumei, P.; Huang, X.; Tu, J.; Ozhogin, P.

2009-04-01

147

Input Decimated Ensembles  

NASA Technical Reports Server (NTRS)

Using an ensemble of classifiers instead of a single classifier has been shown to improve generalization performance in many pattern recognition problems. However, the extent of such improvement depends greatly on the amount of correlation among the errors of the base classifiers. Therefore, reducing those correlations while keeping the classifiers' performance levels high is an important area of research. In this article, we explore input decimation (ID), a method which selects feature subsets for their ability to discriminate among the classes and uses them to decouple the base classifiers. We provide a summary of the theoretical benefits of correlation reduction, along with results of our method on two underwater sonar data sets, three benchmarks from the Probenl/UCI repositories, and two synthetic data sets. The results indicate that input decimated ensembles (IDEs) outperform ensembles whose base classifiers use all the input features; randomly selected subsets of features; and features created using principal components analysis, on a wide range of domains.

Tumer, Kagan; Oza, Nikunj C.; Clancy, Daniel (Technical Monitor)

2001-01-01

148

Regional rainfall climatologies derived from Special Sensor Microwave Imager (SSM/I) data  

NASA Technical Reports Server (NTRS)

Climatologies of convective precipitation were derived from passive microwave observations from the Special Sensor Microwave Imager using a scattering-based algorithm of Adler et al. Data were aggregated over periods of 3-5 months using data from 4 to 5 years. Data were also stratified by satellite overpass times (primarily 06 00 and 18 00 local time). Four regions (Mexico, Amazonia, western Africa, and the western equatorial Pacific Ocean (TOGA COARE area) were chosen for their meteorological interest and relative paucity of conventional observations. The strong diurnal variation over Mexico and the southern United States was the most striking aspect of the climatologies. Pronounced morning maxima occured offshore, often in concativities in the coastline, the result of the increased convergence caused by the coastline shape. The major feature of the evening rain field was a linear-shaped maximum along the western slope of the Sierra Madre Occidental. Topography exerted a strong control on the rainfall in other areas, particularly near the Nicaragua/Honduras border and in Guatemala, where maxima in excess of 700 mm/month were located adjacent to local maxima in terrain. The correlation between the estimates and monthly gage data over the southern United States was low (0.45), due mainly to poor temporal sampling in any month and an inadequate sampling of the diurnal cycle. Over the Amazon Basin the differences in morning versus evening rainfall were complex, with an alternating series of morning/evening maxima aligned southwest to northeast from the Andes to the northeast Brazilian coast. A real extent of rainfall in Amazonia was slightly higher in the evening, but a maximum in morning precipitation was found on the Amazon River just east of Manaus. Precipitation over the water in the intertropical convergence zone (ITCZ) north of Brazil was more pronounced in the morning, and a pronounced land-/sea-breeze circulation was found along the northeast coast of Brazil. Inter-comparison of four years revealed 1992 to be the driest over Amazonia, with about a 23% decrease in mean rate compared to the 4-year mean estimated rain rate.

Negri, Andrew J.; Adler, Robert F.; Nelkin, Eric J.; Huffman, George J.

1994-01-01

149

Use of a Reference Tissue and Blood Vessel to Measure the Arterial Input Function in DCEMRI  

PubMed Central

Accurate measurement of the arterial input function is critical for quantitative evaluation of dynamic contrast enhanced magnetic resonance imaging data. Use of the reference tissue method to derive a local arterial input function avoided large errors associated with direct arterial measurements, but relied on literature values for Ktrans and ve. We demonstrate that accurate values of Ktrans and ve in a reference tissue can be measured by comparing contrast media concentration in a reference tissue to plasma concentrations measured directly in a local artery after the 1–2 passes of the contrast media bolus—when plasma concentration is low and can be measured accurately. The values of Ktrans and ve calculated for the reference tissue can then be used to derive a more complete arterial input function including the first pass of the contrast bolus. This new approach was demonstrated using dynamic contrast enhanced magnetic resonance imaging data from rodent hind limb. Values obtained for Ktrans and ve in muscle, and the shape and amplitude of the derived arterial input function are consistent with published results.

Fan, Xiaobing; Haney, Chad R.; Mustafi, Devkumar; Yang, Cheng; Zamora, Marta; Markiewicz, Erica J.; Karczmar, Gregory S.

2010-01-01

150

Storm diagnostic/predictive images derived from a combination of lightning and satellite imagery  

NASA Technical Reports Server (NTRS)

A technique is presented for generating trend or convective tendency images using a combination of GOES satellite imagery and cloud-to-ground lightning observations. The convective tendency images can be used for short term forecasting of storm development. A conceptual model of cloud electrical development and an example of the methodology used to generate lightning/satellite convective tendency imagery are given. Successive convective tendency images can be looped or animated to show the previous growth or decay of thunderstorms and their associated lighting activity. It is suggested that the convective tendency image may also be used to indicate potential microburst producing storms.

Goodman, Steven J.; Buechler, Dennis E.; Meyer, Paul J.

1988-01-01

151

Recent rapid thinning of the ``Mer de Glace'' glacier derived from satellite optical images  

Microsoft Academic Search

The rapid wastage of mountain glaciers and their contribution to sea level rise require worldwide monitoring of their mass balance. In this paper, we show that changes in glacier thickness can be accurately measured from satellite images. We use SPOT image pairs to build Digital Elevation Models (DEMs) of the Mont Blanc area (French Alps) for different years. To register

E. Berthier; Y. Arnaud; D. Baratoux; C. Vincent; F. Rémy

2004-01-01

152

Enhanced Healing of Diabetic Wounds by Topical Administration of Adipose Tissue-Derived Stromal Cells Overexpressing Stromal-Derived Factor-1: Biodistribution and Engraftment Analysis by Bioluminescent Imaging  

PubMed Central

Chronic ulcers represent a major health problem in diabetic patients resulting in pain and discomfort. Conventional therapy does not guarantee adequate wound repair. In diabetes, impaired healing is partly due to poor endothelial progenitor cells mobilisation and homing, with altered levels of the chemokine stromal-derived factor-1 (SDF-1) at the wound site. Adipose tissue-associated stromal cells (AT-SCs) can provide an accessible source of progenitor cells secreting proangiogenic factors and differentiating into endothelial-like cells. We demonstrated that topical administration of AT-SCs genetically modified ex vivo to overexpress SDF-1, promotes wound healing into diabetic mice. In particular, by in vivo bioluminescent imaging analysis, we monitored biodistribution and survival after transplantation of luciferase-expressing cells. In conclusion, this study indicates the therapeutic potential of AT-SCs administration in wound healing, through cell differentiation, enhanced cellular recruitment at the wound site, and paracrine effects associated with local growth-factors production.

Di Rocco, Giuliana; Gentile, Antonietta; Antonini, Annalisa; Ceradini, Francesca; Wu, Joseph C.; Capogrossi, Maurizio C.; Toietta, Gabriele

2011-01-01

153

Enhanced healing of diabetic wounds by topical administration of adipose tissue-derived stromal cells overexpressing stromal-derived factor-1: biodistribution and engraftment analysis by bioluminescent imaging.  

PubMed

Chronic ulcers represent a major health problem in diabetic patients resulting in pain and discomfort. Conventional therapy does not guarantee adequate wound repair. In diabetes, impaired healing is partly due to poor endothelial progenitor cells mobilisation and homing, with altered levels of the chemokine stromal-derived factor-1 (SDF-1) at the wound site. Adipose tissue-associated stromal cells (AT-SCs) can provide an accessible source of progenitor cells secreting proangiogenic factors and differentiating into endothelial-like cells. We demonstrated that topical administration of AT-SCs genetically modified ex vivo to overexpress SDF-1, promotes wound healing into diabetic mice. In particular, by in vivo bioluminescent imaging analysis, we monitored biodistribution and survival after transplantation of luciferase-expressing cells. In conclusion, this study indicates the therapeutic potential of AT-SCs administration in wound healing, through cell differentiation, enhanced cellular recruitment at the wound site, and paracrine effects associated with local growth-factors production. PMID:21234108

Di Rocco, Giuliana; Gentile, Antonietta; Antonini, Annalisa; Ceradini, Francesca; Wu, Joseph C; Capogrossi, Maurizio C; Toietta, Gabriele

2010-01-01

154

Color Constancy Using 3D Scene Geometry Derived From a Single Image.  

PubMed

The aim of color constancy is to remove the effect of the color of the light source. As color constancy is inherently an ill-posed problem, most of the existing color constancy algorithms are based on specific imaging assumptions (e.g., gray-world and white patch assumption). In this paper, 3D geometry models are used to determine which color constancy method to use for the different geometrical regions (depth/layer) found in images. The aim is to classify images into stages (rough 3D geometry models). According to stage models, images are divided into stage regions using hard and soft segmentation. After that, the best color constancy methods are selected for each geometry depth. To this end, we propose a method to combine color constancy algorithms by investigating the relation between depth, local image statistics, and color constancy. Image statistics are then exploited per depth to select the proper color constancy method. Our approach opens the possibility to estimate multiple illuminations by distinguishing nearby light source from distant illuminations. Experiments on state-of-the-art data sets show that the proposed algorithm outperforms state-of-the-art single color constancy algorithms with an improvement of almost 50% of median angular error. When using a perfect classifier (i.e, all of the test images are correctly classified into stages); the performance of the proposed method achieves an improvement of 52% of the median angular error compared with the best-performing single color constancy algorithm. PMID:25051548

Elfiky, Noha; Gevers, Theo; Gijsenij, Arjan; Gonzalez, Jordi

2014-09-01

155

Development of Novel 123I-Labeled Pyridyl Benzofuran Derivatives for SPECT Imaging of ?-Amyloid Plaques in Alzheimer's Disease  

PubMed Central

Imaging of ?-amyloid (A?) plaques in the brain may facilitate the diagnosis of cerebral ?-amyloidosis, risk prediction of Alzheimer’s disease (AD), and effectiveness of anti-amyloid therapies. The purpose of this study was to evaluate novel 123I-labeled pyridyl benzofuran derivatives as SPECT probes for A? imaging. The formation of a pyridyl benzofuran backbone was accomplished by Suzuki coupling. [123I/125I]-labeled pyridyl benzofuran derivatives were readily prepared by an iododestannylation reaction. In vitro A? binding assays were carried out using A?(1–42) aggregates and postmortem human brain sections. Biodistribution experiments were conducted in normal mice at 2, 10, 30, and 60 min postinjection. A? labeling in vivo was evaluated by small-animal SPECT/CT in Tg2576 transgenic mice injected with [123I]8. Ex vivo autoradiography of the brain sections was performed after SPECT/CT. Iodinated pyridyl benzofuran derivatives showed excellent affinity for A?(1–42) aggregates (2.4 to 10.3 nM) and intensely labeled A? plaques in autoradiographs of postmortem AD brain sections. In biodistribution experiments using normal mice, all these derivatives displayed high initial uptake (4.03–5.49% ID/g at 10 min). [125I]8 displayed the quickest clearance from the brain (1.30% ID/g at 60 min). SPECT/CT with [123I]8 revealed higher uptake of radioactivity in the Tg2576 mouse brain than the wild-type mouse brain. Ex vivo autoradiography showed in vivo binding of [123I]8 to A? plaques in the Tg2576 mouse brain. These combined results warrant further investigation of [123I]8 as a SPECT imaging agent for visualizing A? plaques in the AD brain.

Kimura, Hiroyuki; Watanabe, Hiroyuki; Matsumura, Kenji; Yoshimura, Masashi; Iikuni, Shimpei; Okamoto, Yoko; Ihara, Masafumi; Takahashi, Ryosuke; Saji, Hideo

2013-01-01

156

Regional Rainfall Climatologies Derived from Special Sensor Microwave Imager (SSM/I) Data.  

NASA Astrophysics Data System (ADS)

Climatologies of convective precipitation were derived from passive microwave observations from the Special Sensor Microwave Imager using a scattering-based algorithm of Adler et al. Data were aggregated over periods of 3-5 months using data from 4 to 5 years. Data were also stratified by satellite overpass times(primarily 0600 and l800 local time). Four regions [Mexico, Amazonia, western Africa, and the western equatorial Pacific Ocean (TOGA COARE area)] were chosen for their meteorological interest and relative paucity of conventional observations.The strong diurnal variation over Mexico and the southern United States was the most striking aspect of the climatologies. Pronounced morning maxima occurred offshore, often in concavities in the coastline, the result of the increased convergence caused by the coastline shape. The major feature of the evening rain field was a linear-shaped maximum along the western slope of the Sierra Madre Occidental. Topography exerted a strong control on the rainfall in other areas, particularly near the Nicaragua/Honduras border and in Guatemala, where maxima in excess of 700 mm month1 were located adjacent to local maxima in terrain. The correlation between the estimates and monthly gage data over the southern United States was low (0.45), due mainly to poor temporal sampling in any month and an inadequate sampling of the diurnal cycle.Over the Amazon Basin the differences in morning versus evening rainfall were complex, with an alternating series of morning/evening maxima aligned southwest to northeast from the Andes to the northeast Brazilian coast. Areal extent of rainfall in Amazonia was slightly higher in the evening, but a maximum in morning precipitation was found on the Amazon River just east of Manaus. Precipitation over the water in the ITCZ north of Brazil was more pronounced in the morning, and a pronounced land-/sea-breeze circulation was found along the northeast coast of Brazil. Inter-comparison of four years revealed 1992 to be the driest over Amazonia, with about a 23% decrease in mean rain rate compared to the 4-year mean estimated rain rate.The major rain feature of tropical western Africa was found on the west coast-a pronounced overland evening maximum directly between the coast and a high mountain peak, and a morning maximum directly offshore. An intense, localized morning maximum of over 1000 mm month1 was found at a concavity in the coast at the Bight of Bonny. In the region of the TOGA COARE experiment, precipitation in the ITCZ was greater in November 1989-February 1990,compared to the same period in 1988-1989, notably in the region five degrees either side of the equator from 160°E to the dateline. There was a clear preference in both seasons for morning precipitation over the water. Interesting diurnal effects were found over and offshore of New Guinea and the Solomon Islands. For the eight months studied, averaging both the gauges and Goddard Scattering Algorithm estimates to 2.5° grid boxes yielded a correlation of 0.73, bias of 59.5 mm, and a root-mean-square difference of 131.8 mm-29% and 64%, respectively, of the mean monthly observed rainfall.

Negri, Andrew J.; Adler, Robert F.; Nelkin, Eric J.; Huffman, George J.

1994-07-01

157

CellOrganizer: Image-derived Models of Subcellular Organization and Protein Distribution  

PubMed Central

This chapter describes approaches for learning models of subcellular organization from images. The primary utility of these models is expected to be from incorporation into complex simulations of cell behaviors. Most current cell simulations do not consider spatial organization of proteins at all, or treat each organelle type as a single, idealized compartment. The ability to build generative models for all proteins in a proteome and use them for spatially accurate simulations is expected to improve the accuracy of models of cell behaviors. A second use, of potentially equal importance, is expected to be in testing and comparing software for analyzing cell images. The complexity and sophistication of algorithms used in cell image-based screens and assays (variously referred to as high content screening, high content analysis, or high throughput microscopy) is continuously increasing, and generative models can be used to produce images for testing these algorithms in which the expected answer is known.

Murphy, Robert F.

2014-01-01

158

Reproducibility of subregional trabecular bone micro-architectural measures derived from 7-Tesla magnetic resonance images  

PubMed Central

High-resolution magnetic resonance imaging (MRI) of trabecular bone combined with quantitative image analysis represents a powerful technique to gain insight into trabecular bone micro-architectural derangements in osteoporosis and osteoarthritis. The increased signal-to-noise ratio of ultra high-field MR (?7 Tesla) permits images to be obtained with higher resolution and/or decreased scan time compared to scanning at 1.5/3T. In this small feasibility study, we show high measurement precision for subregional trabecular bone micro-architectural analysis performed on 7T knee MR images. The results provide further support for the use of trabecular bone measures as biomarkers in clinical studies of bone disorders.

Wang, Ligong; Liang, Guoyuan; Babb, James S.; Saha, Punam K.; Regatte, Ravinder R.

2013-01-01

159

Image microarrays derived from tissue microarrays (IMA-TMA): New resource for computer-aided diagnostic algorithm development  

PubMed Central

Background: Conventional tissue microarrays (TMAs) consist of cores of tissue inserted into a recipient paraffin block such that a tissue section on a single glass slide can contain numerous patient samples in a spatially structured pattern. Scanning TMAs into digital slides for subsequent analysis by computer-aided diagnostic (CAD) algorithms all offers the possibility of evaluating candidate algorithms against a near-complete repertoire of variable disease morphologies. This parallel interrogation approach simplifies the evaluation, validation, and comparison of such candidate algorithms. A recently developed digital tool, digital core (dCORE), and image microarray maker (iMAM) enables the capture of uniformly sized and resolution-matched images, with these representing key morphologic features and fields of view, aggregated into a single monolithic digital image file in an array format, which we define as an image microarray (IMA). We further define the TMA-IMA construct as IMA-based images derived from whole slide images of TMAs themselves. Methods: Here we describe the first combined use of the previously described dCORE and iMAM tools, toward the goal of generating a higher-order image construct, with multiple TMA cores from multiple distinct conventional TMAs assembled as a single digital image montage. This image construct served as the basis of the carrying out of a massively parallel image analysis exercise, based on the use of the previously described spatially invariant vector quantization (SIVQ) algorithm. Results: Multicase, multifield TMA-IMAs of follicular lymphoma and follicular hyperplasia were separately rendered, using the aforementioned tools. Each of these two IMAs contained a distinct spectrum of morphologic heterogeneity with respect to both tingible body macrophage (TBM) appearance and apoptotic body morphology. SIVQ-based pattern matching, with ring vectors selected to screen for either tingible body macrophages or apoptotic bodies, was subsequently carried out on the differing TMA-IMAs, with attainment of excellent discriminant classification between the two diagnostic classes. Conclusion: The TMA-IMA construct enables and accelerates high-throughput multicase, multifield based image feature discovery and classification, thus simplifying the development, validation, and comparison of CAD algorithms in settings where the heterogeneity of diagnostic feature morphologic is a significant factor.

Hipp, Jennifer A.; Hipp, Jason D.; Lim, Megan; Sharma, Gaurav; Smith, Lauren B.; Hewitt, Stephen M.; Balis, Ulysses G. J.

2012-01-01

160

A lipophilic thioflavin-T derivative for positron emission tomography (PET) imaging of amyloid in brain  

Microsoft Academic Search

The synthesis of a new lipophilic thioflavin-T analogue (2-[4?-(methylamino)phenyl]benzothiazole, 6) with high affinity for amyloid is reported. Intravenous injection of [11C]-labeled 6 in control mice resulted in high brain uptake. Amyloid deposits were imaged with multiphoton microscopy in the brains of living transgenic mice following the systemic injection of unlabeled 6. [11C]6 is a promising amyloid imaging agent for Alzheimer's

Chester A. Mathis; Brian J. Bacskai; Stephen T. Kajdasz; Megan E. McLellan; Matthew P. Frosch; Bradley T. Hyman; Daniel P. Holt; Yanming Wang; Guo-Feng Huang; Manik L. Debnath; William E. Klunk

2002-01-01

161

Compensation for Spherical Geometric and Absorption Effects on Lower Thermospheric Emission Intensities Derived from High Earth Orbit Images  

NASA Technical Reports Server (NTRS)

Remote sensing of the atmosphere from high earth orbit is very attractive due to the large field of view obtained and a true global perspective. This viewpoint is complicated by earth curvature effects so that slant path enhancement and absorption effects, small from low earth orbit, become dominant even at small nadir view angles. The effect is further complicated by the large range of local times and solar zenith angles in a single image leading to a modulation of the image intensity by a significant portion of the diurnal height variation of the absorbing layer. The latter effect is significant in particular for mesospheric, stratospheric and auroral emissions due to their depth in the atmosphere. As a particular case, the emissions from atomic oxygen (130.4 and 135.6 nm) and molecular nitrogen (two LBH bands, LBHS from 140 to 160 nm and LBHL from 160 to 180 nm) as viewed from the Ultraviolet Imager (UVI) are examined. The LBH emissions are of particular interest since LBHS has significant 02 absorption while LBHL does not, In the case of auroral emissions this differential absorption, well examined in the nadir, gives information about the height of the emission and therefore the energy of the precipitating particles. Using simulations of the viewing geometry and images from the UVI we examine these effects and obtain correction factors to adjust to the nadir case with a significant improvement of the derived characteristic energy. There is a surprisingly large effect on the images from the 02 diurnal layer height changes. An empirical compensation to the nadir case is explored based on the local nadir and local zenith angles for each portion of the image. These compensations are demonstrated as applied to the above emissions in both auroral and dayglow images and compared to models. The extension of these findings to other instruments, emissions and spectral regions is examined.

Swift, W.; Germany, G. A.; Richards, P. G.; Parks, G. K.; Brittnacher, M.; Spann, J. F., Jr.

1997-01-01

162

Handling Input and Output for COAMPS  

NASA Technical Reports Server (NTRS)

Two suites of software have been developed to handle the input and output of the Coupled Ocean Atmosphere Prediction System (COAMPS), which is a regional atmospheric model developed by the Navy for simulating and predicting weather. Typically, the initial and boundary conditions for COAMPS are provided by a flat-file representation of the Navy s global model. Additional algorithms are needed for running the COAMPS software using global models. One of the present suites satisfies this need for running COAMPS using the Global Forecast System (GFS) model of the National Oceanic and Atmospheric Administration. The first step in running COAMPS downloading of GFS data from an Internet file-transfer-protocol (FTP) server computer of the National Centers for Environmental Prediction (NCEP) is performed by one of the programs (SSC-00273) in this suite. The GFS data, which are in gridded binary (GRIB) format, are then changed to a COAMPS-compatible format by another program in the suite (SSC-00278). Once a forecast is complete, still another program in the suite (SSC-00274) sends the output data to a different server computer. The second suite of software (SSC- 00275) addresses the need to ingest up-to-date land-use-and-land-cover (LULC) data into COAMPS for use in specifying typical climatological values of such surface parameters as albedo, aerodynamic roughness, and ground wetness. This suite includes (1) a program to process LULC data derived from observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard NASA s Terra and Aqua satellites, (2) programs to derive new climatological parameters for the 17-land-use-category MODIS data; and (3) a modified version of a FORTRAN subroutine to be used by COAMPS. The MODIS data files are processed to reformat them into a compressed American Standard Code for Information Interchange (ASCII) format used by COAMPS for efficient processing.

Fitzpatrick, Patrick; Tran, Nam; Li, Yongzuo; Anantharaj, Valentine

2007-01-01

163

Improved 3D skeletonization of trabecular bone images derived from in vivo MRI  

NASA Astrophysics Data System (ADS)

Independent of overall bone density, 3D trabecular bone (TB) architecture has been shown to play an important role in conferring strength to the skeleton. Advances in imaging technologies such as micro-computed tomography (CT) and micro-magnetic resonance (MR) now permit in vivo imaging of the 3D trabecular network in the distal extremities. However, various experimental factors preclude a straightforward analysis of the 3D trabecular structure on the basis of these in vivo images. For MRI, these factors include blurring due to patient motion, partial volume effects, and measurement noise. While a variety of techniques have been developed to deal with the problem of patient motion, the second and third issues are inherent limitations of the modality. To address these issues, we have developed a series of robust processing steps to be applied to a 3D MR image and leading to a 3D skeleton that accurately represents the trabecular bone structure. Here we describe the algorithm, provide illustrations of its use with both specimen and in vivo micro-MR images, and discuss the accuracy and quantify the relationship between the original bone structure and the resulting 3D skeleton volume.

Magland, Jeremy F.; Wehrli, Felix W.

2008-04-01

164

Ultraviolet Imaging Telescope images of the reflection nebula NGC 7023 - Derivation of ultraviolet scattering properties of dust grains  

NASA Technical Reports Server (NTRS)

The Ultraviolet Imaging Telescope as part of the Astro-1 mission, was used to obtain high-resolution surface brightness distribution data in six ultraviolet wavelength bands for the bright reflection nebula NGC 7023. From the quantitative comparison of the measured surface brightness gradients ratios of nebular to stellar flux, and detail radial surface brightness profiles with corresponding data from the visible, two major conclusions results: (1) the scattering in the near- and far-ultraviolet in this nebula is more strongly forward-directed than in the visible; (2) the dust albedo in the ultraviolet for wavelengths not less than 140 nm is identical to that in the visible, with the exception of the 220 nm bump in the extinction curve. In the wavelengths region of the bump, the albedo is reduced by 25 to 30 percent in comparison with wavelengths regions both shorter and longer. This lower albedo is expected, if the bump is a pure absorption feature.

Witt, Adolf N.; Petersohn, Jens K.; Bohlin, Ralph C.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P.

1992-01-01

165

Cirrus cloud characteristics derived from volume imaging lidar, high spectral resolution lidar, HIS radiometer, and satellite  

NASA Technical Reports Server (NTRS)

Preliminary measurement results are presented from the Cirrus Remote Sensing Pilot Experiment which used a unique suite of instruments to simultaneously retrieve cirrus cloud visible and IR optical properties, while addressing the disparities between satellite volume averages and local point measurements. The experiment employed a ground-based high resolution interferometer sounder (HIS) and a second Fourier transform spectrometer to measure the spectral radiance in the 4-20 micron band, a correlated high spectral resolution lidar, a volume imaging lidar, a CLASS radiosonde system, the Scripps Whole Sky Imager, and multispectral VAS, HIRS, and AVHRR satellite data from polar orbiting and geostationary satellites. Data acquired during the month long experiment included continuous daytime monitoring with the Whole Sky Imager.

Grund, Christian J.; Ackerman, Steven A.; Eloranta, Edwin W.; Knutsen, Robert O.; Revercomb, Henry E.; Smith, William L.; Wylie, Donald P.

1990-01-01

166

An adaptive `broom balancer' with visual inputs  

Microsoft Academic Search

An adaptive network with visual inputs has been trained to balance an inverted pendulum. Simulation results show that the network is capable of extracting the necessary state information from time sequences of crude visual images. A single linear adaptive threshold element (ADALINE) was adequate for this task. When tested by simulation, the performance achieved was sufficient to keep the pendulum

V. V. Tolat; Bernard Widrow

1988-01-01

167

High-resolution CCD imaging and derived gravitational lens models of 2237+0305  

NASA Technical Reports Server (NTRS)

Images of the gravitational lens 2237+0305 acquired in good seeing have resolved the system into at least five components within the central few arsec of the object: the galaxy nucleus and four point sources in a ringlike formation approximately centered on the galaxy. It is found that the four point sources are distinctly bluer than the galaxy, but that they do not have identical colors. The observed configuration is well reproduced by a simple model that assumes that the four objects are images of the quasar and that the lens is a constant mass-to-light ratio, elliptical, de Vaucouleurs bulge.

Schneider, D. P.; Turner, E. L.; Gunn, J. E.; Hewitt, J. N.; Schmidt, M.

1988-01-01

168

Effect of injection technique on temporal parametric imaging derived from digital subtraction angiography in patient specific phantoms  

NASA Astrophysics Data System (ADS)

Parametric imaging maps (PIM's) derived from digital subtraction angiography (DSA) for the cerebral arterial flow assessment in clinical settings have been proposed, but experiments have yet to determine the reliability of such studies. For this study, we have observed the effects of different injection techniques on PIM's. A flow circuit set to physiologic conditions was created using an internal carotid artery phantom. PIM's were derived for two catheter positions, two different contrast bolus injection volumes (5ml and 10 ml), and four injection rates (5, 10, 15 and 20 ml/s). Using a gamma variate fitting approach, we derived PIM's for mean-transit-time (MTT), time-to-peak (TTP) and bolus-arrivaltime (BAT). For the same injection rates, a larger bolus resulted in an increased MTT and TTP, while a faster injection rate resulted in a shorter MTT, TTP, and BAT. In addition, the position of the catheter tip within the vasculature directly affected the PIM. The experiment showed that the PIM is strongly correlated with the injection conditions, and, therefore, they have to be interpreted with caution. PIM images must be taken from the same patient to be able to be meaningfully compared. These comparisons can include pre- and post-treatment images taken immediately before and after an interventional procedure or simultaneous arterial flow comparisons through the left and right cerebral hemispheres. Due to the strong correlation between PIM and injection conditions, this study indicates that this assessment method should be used only to compare flow changes before and after treatment within the same patient using the same injection conditions.

Ionita, Ciprian N.; Garcia, Victor L.; Bednarek, Daniel R.; Snyder, Kenneth V.; Siddiqui, Adnan H.; Levy, Elad I.; Rudin, Stephen

2014-03-01

169

Derivation of the Magnetic Field in a Coronal Mass Ejection Core via Multi-frequency Radio Imaging  

NASA Astrophysics Data System (ADS)

The magnetic field within the core of a coronal mass ejection (CME) on 2010 August 14 is derived from analysis of multi-wavelength radio imaging data. This CME's core was found to be the source of a moving type IV radio burst, whose emission is here determined to arise from the gyrosynchrotron process. The CME core's true trajectory, electron density, and line-of-sight depth are derived from stereoscopic observations, constraining these parameters in the radio emission models. We find that the CME carries a substantial amount of mildly relativistic electrons (E < 100 keV) in a strong magnetic field (B < 15 G), and that the spectra at lower heights are preferentially suppressed at lower frequencies through absorption from thermal electrons. We discuss the results in light of previous moving type IV burst studies, and outline a plan for the eventual use of radio methods for CME magnetic field diagnostics.

Tun, Samuel D.; Vourlidas, A.

2013-04-01

170

DERIVATION OF THE MAGNETIC FIELD IN A CORONAL MASS EJECTION CORE VIA MULTI-FREQUENCY RADIO IMAGING  

SciTech Connect

The magnetic field within the core of a coronal mass ejection (CME) on 2010 August 14 is derived from analysis of multi-wavelength radio imaging data. This CME's core was found to be the source of a moving type IV radio burst, whose emission is here determined to arise from the gyrosynchrotron process. The CME core's true trajectory, electron density, and line-of-sight depth are derived from stereoscopic observations, constraining these parameters in the radio emission models. We find that the CME carries a substantial amount of mildly relativistic electrons (E < 100 keV) in a strong magnetic field (B < 15 G), and that the spectra at lower heights are preferentially suppressed at lower frequencies through absorption from thermal electrons. We discuss the results in light of previous moving type IV burst studies, and outline a plan for the eventual use of radio methods for CME magnetic field diagnostics.

Tun, Samuel D. [The Naval Research Laboratory, Washington, DC 20375 (United States)] [The Naval Research Laboratory, Washington, DC 20375 (United States); Vourlidas, A. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)] [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

2013-04-01

171

EFM data mapped into 2D images of tip-sample contact potential difference and capacitance second derivative.  

PubMed

We report a simple technique for mapping Electrostatic Force Microscopy (EFM) bias sweep data into 2D images. The method allows simultaneous probing, in the same scanning area, of the contact potential difference and the second derivative of the capacitance between tip and sample, along with the height information. The only required equipment consists of a microscope with lift-mode EFM capable of phase shift detection. We designate this approach as Scanning Probe Potential Electrostatic Force Microscopy (SPP-EFM). An open-source MATLAB Graphical User Interface (GUI) for images acquisition, processing and analysis has been developed. The technique is tested with Indium Tin Oxide (ITO) and with poly(3-hexylthiophene) (P3HT) nanowires for organic transistor applications. PMID:24284731

Lilliu, S; Maragliano, C; Hampton, M; Elliott, M; Stefancich, M; Chiesa, M; Dahlem, M S; Macdonald, J E

2013-01-01

172

EFM data mapped into 2D images of tip-sample contact potential difference and capacitance second derivative  

NASA Astrophysics Data System (ADS)

We report a simple technique for mapping Electrostatic Force Microscopy (EFM) bias sweep data into 2D images. The method allows simultaneous probing, in the same scanning area, of the contact potential difference and the second derivative of the capacitance between tip and sample, along with the height information. The only required equipment consists of a microscope with lift-mode EFM capable of phase shift detection. We designate this approach as Scanning Probe Potential Electrostatic Force Microscopy (SPP-EFM). An open-source MATLAB Graphical User Interface (GUI) for images acquisition, processing and analysis has been developed. The technique is tested with Indium Tin Oxide (ITO) and with poly(3-hexylthiophene) (P3HT) nanowires for organic transistor applications.

Lilliu, S.; Maragliano, C.; Hampton, M.; Elliott, M.; Stefancich, M.; Chiesa, M.; Dahlem, M. S.; MacDonald, J. E.

2013-11-01

173

Evaluation of a 125I-labelled benzazepinone derived voltage-gated sodium channel blocker for imaging with SPECT.  

PubMed

Voltage-gated sodium channels (VGSCs) are a family of transmembrane proteins that mediate fast neurotransmission, and are integral to sustain physiological conditions and higher cognitive functions. Imaging of VGSCs in vivo holds promise as a tool to elucidate operational functions in the brain and to aid the treatment of a wide range of neurological diseases. To assess the suitability of 1-benzazepin-2-one derived VGSC blockers for imaging, we have prepared a (125)I-labelled analogue of BNZA and evaluated the tracer in vivo. In an automated patch-clamp assay, a diastereomeric mixture of the non-radioactive compound blocked the Na(v)1.2 and Na(v)1.7 VGSC isoforms with IC(50) values of 4.1 ± 1.5 ?M and 0.25 ± 0.07 ?M, respectively. [(3)H]BTX displacement studies revealed a three-fold difference in affinity between the two diastereomers. Iodo-destannylation of a tin precursor with iodine-125 afforded the two diastereomerically pure tracers, which were used to assess binding to VGSCs in vivo by comparing their tissue distributions in mice. Whilst the results point to a lack of VGSC binding in vivo, SPECT imaging revealed highly localized uptake in the interscapular region, an area typically associated with brown adipose tissue, which in addition to high metabolic stability of the iodinated tracer, demonstrate the potential of 1-benzazepin-2-ones for in vivo imaging. PMID:23117159

Pérez-Medina, Carlos; Patel, Niral; Robson, Mathew; Badar, Adam; Lythgoe, Mark F; Årstad, Erik

2012-12-21

174

Effects of quantum noise in 4D-CT on deformable image registration and derived ventilation data  

NASA Astrophysics Data System (ADS)

Quantum noise is common in CT images and is a persistent problem in accurate ventilation imaging using 4D-CT and deformable image registration (DIR). This study focuses on the effects of noise in 4D-CT on DIR and thereby derived ventilation data. A total of six sets of 4D-CT data with landmarks delineated in different phases, called point-validated pixel-based breathing thorax models (POPI), were used in this study. The DIR algorithms, including diffeomorphic morphons (DM), diffeomorphic demons (DD), optical flow and B-spline, were used to register the inspiration phase to the expiration phase. The DIR deformation matrices (DIRDM) were used to map the landmarks. Target registration errors (TRE) were calculated as the distance errors between the delineated and the mapped landmarks. Noise of Gaussian distribution with different standard deviations (SD), from 0 to 200 Hounsfield Units (HU) in amplitude, was added to the POPI models to simulate different levels of quantum noise. Ventilation data were calculated using the ?V algorithm which calculates the volume change geometrically based on the DIRDM. The ventilation images with different added noise levels were compared using Dice similarity coefficient (DSC). The root mean square (RMS) values of the landmark TRE over the six POPI models for the four DIR algorithms were stable when the noise level was low (SD <150 HU) and increased with added noise when the level is higher. The most accurate DIR was DD with a mean RMS of 1.5 ± 0.5 mm with no added noise and 1.8 ± 0.5 mm with noise (SD = 200 HU). The DSC values between the ventilation images with and without added noise decreased with the noise level, even when the noise level was relatively low. The DIR algorithm most robust with respect to noise was DM, with mean DSC = 0.89 ± 0.01 and 0.66 ± 0.02 for the top 50% ventilation volumes, as compared between 0 added noise and SD = 30 and 200 HU, respectively. Although the landmark TRE were stable with low noise, the differences between ventilation images increased with noise level, even when the noise was low, indicating ventilation imaging from 4D-CT was sensitive to image noise. Therefore, high quality 4D-CT is essential for accurate ventilation images.

Latifi, Kujtim; Huang, Tzung-Chi; Feygelman, Vladimir; Budzevich, Mikalai M.; Moros, Eduardo G.; Dilling, Thomas J.; Stevens, Craig W.; van Elmpt, Wouter; Dekker, Andre; Zhang, Geoffrey G.

2013-11-01

175

Mean height and variability of height derived from lidar data and Landsat images relationship  

Microsoft Academic Search

The mean and standard deviation of lidar-derived height data have shown to be important variables with which to summarize forest structure. However, lidar data has a limited spatial extent and a very high economic cost. Landsat data provides useful structural information in the horizontal plane and is easily accessible. The integration of both data sources offers an interesting opportunity to

Cristina Pascual; Warren Cohen; Antonio García-Abril; Lara A. Arroyo; Rubén Valbuena; Susana Martí-Fernández; José Antonio Manzanera

2008-01-01

176

Evaluating Benthic Survey Techniques for Validating Maps of Coral Reefs Derived from Remotely Sensed Images  

Microsoft Academic Search

Field validation of maps derived from airborne or satellite imagery is essential to enable their use for monitoring and managing coral reef habitats. Methods of benthic survey in coral reef ecosystems have been documented elsewhere, yet a comparative evaluation of methods for integrating field data with remote sensing has not been completed. In addition to meeting standard field survey requirements,

Chris M. ROELFSEMA; Stuart R. PHINN

177

Derivation of complex resistivity values from MFEIT images formed with reactive references  

Microsoft Academic Search

The electrical response of tissue conveys information about the nature of tissue at a cellular level. Several methods have been described in the literature to determine the complex resistivity of tissue from pixels of multi-frequency electrical impedance tomography (MFEIT) images. These methods are limited in use by the requirement of a homogeneous, resistive reference or by the assumption that the

A. Fitzgerald; H. Griffiths

1998-01-01

178

Global Neutral gas Distribution at Saturn and Jupiter Derived From ENA Images  

NASA Astrophysics Data System (ADS)

Neutral gas distributions around giant planets are important indicators of the source, loss and transport processes that redistribute material from the planet, its moons and rings, through interaction with the ambient plasma of the magnetosphere. Energetic Neutral Atoms (ENAs) are produced by charge exchange between energetic ions and neutral gas and can be imaged by the INCA camera on board Cassini providing a marker for plasma-neutral processes. As Cassini flew by Jupiter Cassini-INCA data was used to reveal a trans- Europa gas torus [Mauk et al., Nature, 2003]. We demonstrate a technique to retrieve the global neutral gas distribution in Saturn's magnetosphere using ENA images obtained from the INCA imager on board Cassini. The neutral gas distribution at Saturn is retrieved by simulating INCA images using ion distributions of combined CHEMS, LEMMS and INCA in-situ ion measurements that cover several passes from the SOI (183/2004) to day 100/2007, at various local times over the dipole L range 5

Dialynas, K.; Brandt, P. C.; Krimigis, S. M.; Mauk, B. H.; Mitchell, D. G.; Hamilton, D. C.; Krupp, N.; Rymer, A. M.; Smith, H. T.

2008-12-01

179

White synthesis with user input for color balancing on mobile camera systems  

NASA Astrophysics Data System (ADS)

In this paper we extend the manual white balancing technique available on most imaging devices by allowing a user to specify arbitrary colors in the scene. We derive an interpolation technique to assign weights to the arbitrary colors which are then used to estimate the RGB complements corresponding to a white target. We obtain the user input by displaying a captured image alongside a color grid of commonly occurring colors. The user specifies color pairs - patches in the scene and veridical colors on the grid. We then use these pairs to estimate the white point with our interpolation method. The estimated white point is then used to construct a diagonal transform to determine the camera output under a desired illuminant. We will present results from testing our methods on images acquired under several illumination conditions. Our approach is very suitable for mobile devices because most mobile devices are equipped with moderately sophisticated imaging systems and our method allows better color capture with relatively little user input. Further, we can realize our method on mobile devices since these devices have built-in tools for graphical user input. Our method can be useful in several photography and image analysis applications.

Srivastava, Satyam; Xu, Chang; Delp, Edward J.

2012-02-01

180

Equalizers for Multiple Input\\/Multiple Output Channels and PAM Systems with Cyclostationary Input Sequences  

Microsoft Academic Search

The author studies minimum mean square error (MMSE) linear and decision feedback (DF) equalisers for multiple input\\/multiple output (MIMO) communication systems with intersymbol interference (ISI) and wide-sense stationary (WSS) inputs. To derive these equalizers, one works in the D-transform domain and uses prediction theory results. Partial-response MMSE equalizers are also found. As an application, the author considers a pulse amplitude

Alexandra Duel-hallen

1992-01-01

181

Comparison of epicardial potential maps derived from the 12-lead electrocardiograms with scintigraphic images during controlled myocardial ischemia.  

PubMed

Our aim was to cross-validate electrocardiographic (ECG) and scintigraphic imaging of acute myocardial ischemia. The former method was based on inverse calculation of heart-surface potentials from the body-surface ECGs, and the latter, on a single photon emission computed tomography (SPECT). A boundary-element torso model with 352 body-surface and 202 heart-surface nodes was used to perform the ECG inverse solution. Potentials at 352 body-surface nodes were calculated from those acquired at 12-lead ECG measurement sites using regression coefficients developed from a design set (n = 892) of body-surface potential mapping (BSPM) data. The test set (n = 18) consisted of BSPM data from patients who underwent a balloon-inflation angioplasty of either the left anterior descending coronary artery (LAD) (n = 7), left circumflex coronary artery (LCx) (n = 2), or the right coronary artery (RCA) (n = 9). Body-surface potential mapping distributions at J point for 352 nodes were estimated from the 12-lead ECG, and an agreement with those estimated from 120 leads was assessed by a correlation coefficient (CC) (in percent). These estimates yielded very similar BSPM distributions, with a CC of 91.0% ± 8.1% (mean ± SD) for the entire test set and 94.1% ± 1.4%, 96.7% ± 0.8%, and 87.4% ± 10.3% for LAD, LCx, and RCA subgroups, respectively. Corresponding heart-surface potential distributions obtained by inverse solution correlated with a lower CC of 69.3% ± 18.0% overall and 73.7% ± 10.8%, 84.7% ± 1.1%, and 62.6% ± 21.8%, respectively, for subgroups. Bull's-eye displays of heart-surface potentials calculated from estimated BSPM distributions had an area of positive potentials that qualitatively corresponded, in general, with the underperfused territory suggested by SPECT images. For the LAD and LCx groups, all 9 ECG-derived bull's-eye images indicated the expected territory; for the RCA group, 6 of 9 ECG-derived images were as expected; 2 of 3 misclassified cases had very small ECG changes in response to coronary-artery occlusion, and their SPECT images showed indiscernible patterns. In conclusion, our findings demonstrate that noninvasive ECG imaging based on just the 12-lead ECG might provide useful estimates of the regions of myocardial ischemia that agree with those provided by scintigraphic techniques. PMID:22018485

Horá?ek, B Milan; Sapp, John L; Penney, Cindy J; Warren, James W; Wang, John J

2011-01-01

182

High Resolution Vesta Survey Atlas derived from Dawn-FC images  

NASA Astrophysics Data System (ADS)

In August 2011, the Dawn Framing Camera will acquire hundreds of high-resolution images (about 250 m/pixel) during its Survey orbit around Vesta. We will combine these images to a global controlled ortho-rectified mosaic of Vesta. This global mosaic is the basis for the high-resolution Vesta Survey atlas that consists of 4 tiles (subdivision of the synoptic format) mapped at a scale of 1:1,500,000. The nomenclature used in this atlas will be based on names and places historically associated with the Roman goddess Vesta. The Dawn team will propose feature names compliant with the rules of the IAU. Selected examples of map sheets of the atlas will be shown in this presentation.

Roatsch, T.; Kersten, E.; Preusker, F.; Scholten, F.; Jaumann, R.; Coradini, A.; Nathues, A.; Raymond, C. A.; Russell, C. T.

2011-12-01

183

Statistical Storm-Time Examination of MLT Dependent Plasmapause Location Derived from IMAGE EUV  

NASA Astrophysics Data System (ADS)

The location of the outer edge of the plasmaphere (the plasmapause) as a function of geomagnetic storm-time is investigated statistically in terms of the solar wind driver. Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) Extreme Ultraviolet (EUV) data is used in an automated plasmapause extraction. The extraction technique searches a set range of possible plasmasphere densities for a maximum gradient. The magnetic local time (MLT) dependent plasmapause results are then compared to manual extractions. The plasmapause results are then examined along a normalized epoch storm timeline to determine the average plasmapause Lshell as a function of MLT and storm time. The smoothness of the plasmapause is inspected to describe the spatial scale of the electric field. The results are then investigated in terms of the solar wind driver and the storm intensity.

Katus, R. M.; Gallagher, D. L.; Liemohn, M. W.; Goldstein, J.

2013-12-01

184

High resolution Vesta High Altitude Mapping Orbit (HAMO) Atlas derived from Dawn framing camera images  

NASA Astrophysics Data System (ADS)

The Dawn framing camera (FC) acquired about 2500 clear filter images of Vesta with a resolution of about 70 m/pixels during the High Altitude Mapping Orbit (HAMO) in fall 2011. We ortho-rectified these images and produced a global high resolution controlled mosaic of Vesta. This global mosaic is the baseline for a high resolution Vesta atlas that consists of 15 tiles mapped at a scale of 1:500,000. The nomenclature used in this atlas was proposed by the Dawn team and was approved by the International Astronomical Union (IAU). The whole atlas is available to the public through the Dawn GIS web page [http://dawn_gis.dlr.de/atlas].

Roatsch, Th.; Kersten, E.; Matz, K.-D.; Preusker, F.; Scholten, F.; Jaumann, R.; Raymond, C. A.; Russell, C. T.

2012-12-01

185

Pixel-by-Pixel Spatiotemporal Progression of Focal Ischemia Derived Using Quantitative Perfusion and Diffusion Imaging  

Microsoft Academic Search

Summary: Pixel-by-pixel spatiotemporal progression of focal ischemia (permanent occlusion) in rats was investigated using quantitative perfusion and diffusion magnetic resonance imag- ing every 30 minutes for 3 hours. The normal left-hemisphere apparent diffusion coefficient (ADC) was 0.76 ± 0.03 × 10?3 mm2\\/s and CBF was 0.7 ± 0.3 mL · g?1 · min?1 (mean ± SD, n5). The ADC and

Qiang Shen; Xiangjun Meng; Marc Fisher; Christopher H. Sotak; Timothy Q. Duong

186

The July urban heat island of Bucharest as derived from modis images  

Microsoft Academic Search

The urban heat island (UHI) of the city of Bucharest (Romania) is analyzed in terms of its extension, geometry, and magnitude\\u000a using the surface thermal data provided by the moderate resolution imaging spectroradiometer (MODIS) sensors. An objective\\u000a method is developed that allows to delineate the UHI. The study focuses on the months of July from the 2000–2006 time interval.\\u000a The

S. Cheval; A. Dumitrescu

2009-01-01

187

Copper-free click reactions with polar bicyclononyne derivatives for modulation of cellular imaging.  

PubMed

The ability of cells to incorporate azidosugars metabolically is a useful tool for extracellular glycan labelling. The exposed azide moiety can covalently react with alkynes, such as bicyclo[6.1.0]nonyne (BCN), by strain-promoted alkyne-azide cycloaddition (SPAAC). However, the use of SPAAC can be hampered by low specificity of the cycloalkyne. In this article we describe the synthesis of more polar BCN derivatives and their properties for selective cellular glycan labelling. The new polar derivatives [amino-BCN, glutarylamino-BCN and bis(hydroxymethyl)-BCN] display reaction rates similar to those of BCN and are less cell-permeable. The labelling specificity in HEK293 cells is greater than that of BCN, as determined by confocal microscopy and flow cytometry. Interestingly, amino-BCN appears to be highly specific for the Golgi apparatus. In addition, the polar BCN derivatives label the N-glycan of the membrane calcium channel TRPV5 in HEK293 cells with significantly enhanced signal-to-noise ratios. PMID:24904006

Leunissen, E H P; Meuleners, M H L; Verkade, J M M; Dommerholt, J; Hoenderop, J G J; van Delft, F L

2014-07-01

188

Partial dependence of breast tumor malignancy on ultrasound image features derived from boosted trees  

NASA Astrophysics Data System (ADS)

Various computerized features extracted from breast ultrasound images are useful in assessing the malignancy of breast tumors. However, the underlying relationship between the computerized features and tumor malignancy may not be linear in nature. We use the decision tree ensemble trained by the cost-sensitive boosting algorithm to approximate the target function for malignancy assessment and to reflect this relationship qualitatively. Partial dependence plots are employed to explore and visualize the effect of features on the output of the decision tree ensemble. In the experiments, 31 image features are extracted to quantify the sonographic characteristics of breast tumors. Patient age is used as an external feature because of its high clinical importance. The area under the receiver-operating characteristic curve of the tree ensembles can reach 0.95 with sensitivity of 0.95 (61/64) at the associated specificity 0.74 (77/104). The partial dependence plots of the four most important features are demonstrated to show the influence of the features on malignancy, and they are in accord with the empirical observations. The results can provide visual and qualitative references on the computerized image features for physicians, and can be useful for enhancing the interpretability of computer-aided diagnosis systems for breast ultrasound.

Yang, Wei; Zhang, Su; Li, Wenying; Chen, Yaqing; Lu, Hongtao; Chen, Wufan; Chen, Yazhu

2010-04-01

189

Hyaluronic acid derivative-coated nanohybrid liposomes for cancer imaging and drug delivery.  

PubMed

Nanohybrid liposomes coated with amphiphilic hyaluronic acid-ceramide (HACE) was fabricated for targeted delivery of anticancer drug and in vivo cancer imaging. Nanohybrid liposomes including doxorubicin (DOX) and Magnevist, a contrast agent for magnetic resonance (MR) imaging, with 120-130nm mean diameter and a narrow size distribution were developed. DOX release from the developed formulation was improved at acidic pH (pH5.5 and 6.8) versus physiological pH (pH7.4). Cytotoxicity induced by the blank plain liposome was reduced by coating the outer surface of the nanohybrid liposome with HACE. Cellular uptake of DOX from the nanohybrid liposome was enhanced by HA and CD44 receptor interaction, versus the plain liposome. In vivo contrast-enhancing effects revealed that the nanohybrid liposome can be used as a tumor targeting MR imaging probe for cancer diagnosis. In a pharmacokinetic study in rats, in vivo clearance of DOX was decreased in the order DOX solution, plain liposome (F2), and nanohybrid liposome (F3), indicating prolonged circulation of the drug in the blood stream and improved therapeutic efficacy of the nanohybrid liposome (F3). Based on these findings, the nanohybrid liposomal system may be a useful candidate for real-time cancer diagnosis and therapy. PMID:24280260

Park, Ju-Hwan; Cho, Hyun-Jong; Yoon, Hong Yeol; Yoon, In-Soo; Ko, Seung-Hak; Shim, Jae-Seong; Cho, Jee-Hyun; Park, Jae Hyung; Kim, Kwangmeyung; Kwon, Ick Chan; Kim, Dae-Duk

2014-01-28

190

Visualizing 2D Probability Distributions from Satellite Image-Derived Data  

NASA Technical Reports Server (NTRS)

Creating maps of biophysical and geophysical variables using Earth Observing System (EOS) satellite image data is an important component of Earth science. These 2D maps have a single value at every location and standard techniques are used to visualize them. Current tools fall short, however, when it is necessary to describe a distribution of values at each location. Distributions may represent a frequency of occurrence over time, frequency of occurrence from multiple runs of an ensemble forecast or possible values from an uncertainty model. 'Distribution data sets' are described, then a case study is presented to visualize such 2D distributions. Distribution data sets are different from multivariate data sets in the sense that the values are for a single variable instead of multiple variables. Our case study data consists of multiple realizations of percent forest cover, generated using a geostatistical technique that combines ground measurements and satellite imagery to model uncertainty about forest cover. We present several approaches for analyzing and visualizing such data sets. The first is a pixel-wise analysis of the probability density functions for the 2D image while the second is an analysis of features identified within the image. Such pixel-wise and feature-wise views will give Earth scientists a more complete understanding of distribution data sets.

Kao, David; Dungan, Jennifer; Pang, Alex; Biegel, Bryan (Technical Monitor)

2002-01-01

191

Extreme inputs/outputs for multiple input multiple output linear systems.  

SciTech Connect

A linear structure is excited at multiple points with a stationary normal random process. The response of the structure is measured at multiple outputs. If the auto spectral densities of the inputs are specified, the phase relationships between the inputs are derived that will minimize or maximize the trace of the auto spectral density matrix of the outputs. If the autospectral densities of the outputs are specified, the phase relationships between the outputs that will minimize or maximize the trace of the input auto spectral density matrix are derived. It is shown that other phase relationships and ordinary coherence less than one will result in a trace intermediate between these extremes. Least favorable response and some classes of critical response are special cases of the development. It is shown that the derivation for stationary random waveforms can also be applied to nonstationary random, transients, and deterministic waveforms.

Smallwood, David Ora

2005-09-01

192

Cellular Bioenergetics is an Important Determinant of the Molecular Imaging Signal Derived from Luciferase and the Sodium-Iodide Symporter  

PubMed Central

Rationale Molecular imaging is useful for longitudinal assessment of engraftment. However, it is not known which factors, other than cell number can influence the molecular imaging signal obtained from reporter genes. Objective The effects of cell dissociation/suspension on cellular bioenergetics and the signal obtained by firefly luciferase(fluc) and human Na-I symporter(hNIS) labeling of cardiosphere-derived cells (CDCs) was investigated. Methods and Results 18FDG uptake, ATP levels, 99mTc-pertechnetate uptake and bioluminescence were measured in vitro, in adherent and suspended CDCs. In vivo dual isotope SPECT-CT imaging or bioluminescence imaging (BLI) were performed 1hr and 24hrs following CDC transplantation. SPECT quantification was performed using a phantom for signal calibration. Cell loss between 1hr & 24hrs post-transplantation was quantified by qPCR and ex vivo luciferase assay. Cell dissociation followed by suspension for 1hr resulted in decreased glucose uptake, cellular ATP, 99mTc uptake and BLI signal by 82%, 43%, 42%, and 44% respectively, when compared to adherent cells, in vitro. In vivo 99mTc uptake was significantly lower at 1hr, when compared to 24hrs following cell transplantation in the non-infarct (p<0.001, n=3) and infarct (p<0.001, n =4) model, despite significant cell loss during this period. The in vivo BLI signal was significantly higher at 1hr than at 24hrs (p<0.01), with the BLI signal being higher when CDCs were suspended in glucose-containing medium compared to saline(PBS). Conclusion Adhesion is an important determinant of cellular bioenergetics, 99mTc-pertechnetate uptake and BLI signal. BLI and NIS imaging may be useful for in vivo optimization of bioenergetics in transplanted cells.

Chang, Connie; Chan, Angel; Lin, Xiaoping; Higuchi, Takahiro; Terrovitis, John; Afzal, Junaid M.; Rittenbach, Andrew; Sun, Dongdong; Vakrou, Styliani; Woldemichael, Kirubel; O'Rourke, Brian; Wahl, Richard; Pomper, Martin; Tsui, Benjamin; Abraham, M. Roselle

2013-01-01

193

Nuclear inputs for nucleosynthesis applications  

SciTech Connect

Although an important effort has been devoted in the last decades to measure reaction cross sections of interest in astrophysics, most nuclear astrophysics applications still require the use of theoretical predictions to estimate experimentally unknown rates. The nuclear ingredients to the reaction model should preferably be estimated from microscopic or semi-microscopic global predictions based on sound and reliable nuclear models which, in turn, can compete with more phenomenological highly-parametrized models in the reproduction of experimental data. The latest developments made in deriving the nuclear inputs of relevance in astrophysics applications are reviewed. They mainly concern nuclear structure properties, nuclear level densities, optical potentials.New developments to improve the predictions of radiative neutron capture rates are also discussed. They include the recent improvements made to the TALYS reaction code and the analysis of the pre-equilibrium contribution. The direct reaction mechanism is also discussed and new estimates on the basis of the newly-derived nuclear ingredients are compared with the compound-nucleus contribution.

Goriely, S.; Chamel, N. [IAA, ULB, Campus de la Plaine, CP 226, 1050 Brussels (Belgium); Hilaire, S. [CEA/DAM, DPTA/Service de Physique Nucleaire, BP 12, 91680 Bruyeres-le-Chatel (France)

2009-01-28

194

Synthesis and preliminary evaluation of [18F]-labeled 2-oxoquinoline derivatives for PET imaging of cannabinoid CB2 receptor  

PubMed Central

Introduction The cannabinoid receptor type 2 (CB2) is an important target for development of drugs and imaging agents for diseases, such as neuroinflammation, neurodegeneration, and cancer. Recently we reported synthesis and results of in vitro receptor binding of a focused library of fluorinated 2-oxoquinoline derivatives as CB2 receptor ligands. Some of the compounds demonstrated as good CB2-specific ligands with Ki values in the nanomolar to sub-nanomolar concentrations; therefore, we pursued the development of their 18F-labeled analogues that should be useful for PET imaging of CB2 receptor expression. Here, we report the radiosynthesis of two 18F-labeled 2-oxoquinoline derivatives, and preliminary in vitro and ex-vivo evaluation of one compound as a CB2-specific radioligand. Methods 4-[18F]Fluorobenzyl amine [18F]-3 was prepared by radiofluorination of 4-cyano-N,N,N-trimethylanilinium triflate salt followed by reduction with LiAlH4 and then coupled with acid chlorides 11 and 12 to afford [18F]-13 and [18F]-14. In vitro CB2 receptor binding assay was performed using U87 cells transduced with CB2- and CB1-receptor. Ex-vivo autoradiography was performed with [18F]-14 on spleen, CB2- and CB1-expressing and wild type U87 subcutaneous tumors grown in mice. Results The radiochemical yields of [18F]-13 and [18F]-14 were 10%-15.0% with an average of 12% (n=10); radiochemical purity was > 99% with specific activity 1200 mCi/?mole. The dissociation constant Kd for [18F]-14 was 3.4 nM. Ex-vivo autoradiography showed accumulation of [18F]-14 in the CB2-expressing tumor. Conclusion Two new [18F]-labeled CB2 ligands have been synthesized. Compound [18F]-14 appears to be a potential PET imaging agent for the assessment of CB2 receptor expression in vivo.

Turkman, Nashaat; Paolillo, Vincenzo; Shavrin, Aleksander; Yeh, Hsin Hsien; Flores, Leo; Soghomonian, Suren; Ravinovich, Brian; Volgin, Andrei; Gelovani, Juri; Alauddin, Mian

2011-01-01

195

Demonstration of a Sucrose-derived Contrast Agent for Magnetic Resonance Imaging of the GI Tract  

PubMed Central

A scaffold bearing eight terminal alkyne groups was synthesized from sucrose, and copies of an azide-terminated Gd-DOTA complex were attached via copper(I)-catalyzed azide-alkyne cycloaddition. The resulting contrast agent (CA) was administered by gavage to C3H mice. Passage of the CA through the gastrointestinal (GI) tract was followed by T1-weighted magnetic resonance imaging (MRI) over a period of 47 hours, by which time the CA had exited the GI tract. No evidence for leakage of the CA from the GI tract was observed. Thus, a new, orally administered CA for MRI of the GI tract has been developed and successfully demonstrated.

Martinez, Gary V.; Navath, Suryakiran; Sewda, Kamini; Rao, Venkataramanarao; Foroutan, Parastou; Alleti, Ramesh; Moberg, Valerie E.; Ahad, Ali M.; Coppola, Domenico; Lloyd, Mark C.; Gillies, Robert J.; Morse, David L.; Mash, Eugene A.

2013-01-01

196

Carbon-dots derived from nanodiamond: photoluminescence tunable nanoparticles for cell imaging.  

PubMed

Water dispersible carbon-dots (CDs) with tunable photoluminescence were synthesized via one-pot hydrothermal oxidation of nanodiamond and subsequently utilized for cell imaging applications. The CDs were characterized by the following techniques including transmission electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, UV-Visible spectroscopy, and fluorescent spectroscopy. Results showed that the size of CDs is mainly distributed at 3-7 nm. Many functional groups were introduced on the surface of CDs during hydrothermal oxidation procedure. Cell morphology observation and cell viability measurement demonstrated the good biocompatibility of CDs, suggesting their potential bioimaging applications. PMID:23484769

Zhang, Xiaoyong; Wang, Shiqi; Zhu, Chongyu; Liu, Meiying; Ji, Yan; Feng, Lin; Tao, Lei; Wei, Yen

2013-05-01

197

Imaging studies of photodamage and recovery of anthraquinone derivatives doped into PMMA  

NASA Astrophysics Data System (ADS)

One of the efficiency-limiting factors of optical devices used at high intensities is photo damage to the optical materials. In devices that use organic dyes, photo damage causes irreversible damage to the chromophores, deteriorating efficiency, and eventually causes failure. Our present work focuses on monitoring degradation and recovery of anthraquinone dye doped PMMA thin films with a digital imaging apparatus, with the goal of understanding the mechanisms. Our results suggest the possibility of making optical components more resistant to photodamage, and capable of self recovery, removing the necessity to constantly replace components damaged by high intensity light.

Anderson, Benjamin; Ramini, Shiva K.; Kuzyk, Mark G.

2011-10-01

198

Synthesis, radiolabeling, and preliminary evaluation in mice of some (N-diethylaminoethyl)-4-iodobenzamide derivatives as melanoma imaging agents.  

PubMed

N-(2-Diethylaminoethyl)-4-iodobenzamide (BZA) is a radiopharmaceutical recently developed in our laboratory for the scintigraphic detection of melanoma and metastases. Optimal time for imaging was between 18-24 h p.i. of [123I] BZA. With a view to selecting compounds able to provide quality images shortly after the injection, synthesis of an initial series of BZA derivatives and their evaluation in B16 melanoma bearing mice have been carried out. The [125I] radiolabeled products were obtained by a simple isotopic exchange procedure with high radiochemical yields (85-95%). After i.v. administration of the compounds we observed a good tumoral targeting ability. Tumoral activity peaked at 2.6 to 7.70% injected dose per g within 1 h post-injection. One of the benzamides with a blood clearance faster than that of BZA--0.06 vs. 0.2% I D/g--6 h p.i. gave the same tumor to blood and to organ ratios as BZA at 12-18 h p.i. Based on these preclinical data we hope to obtain good tumoral images 6 h p.i. in scintigraphic studies in man. PMID:8535334

Moreau, M F; Michelot, J; Papon, J; Bayle, M; Labarre, P; Madelmont, J C; Parry, D; Boire, J Y; Moins, N; Seguin, H

1995-08-01

199

Potential for downscaling soil moisture maps derived from spaceborne imaging radar data  

NASA Astrophysics Data System (ADS)

The presence of nonlinear relationships between surface soil moisture and various hydrologic processes suggests that grid-scale water and energy fluxes cannot be accurately modeled without subgrid-scale soil moisture information. For land surface and energy balance models run over continental- to global-scale domains, accurate fine-scale soil moisture observations are nearly impossible to obtain on a consistent basis and will likely remain so through the next generation of soil moisture remote sensors. In the absence of such data sets, an alternative approach is to generalize the statistical behavior of soil moisture fields across the relevant range of spatial scales. Downscaling procedures offer the possibility that the fine-scale statistical properties of soil moisture fields can be inferred from coarse-scale data. Such an approach was used for a 29×200 km transect of 25 m active radar data acquired over Oklahoma by NASA's spaceborne imaging radar imaging (SIR-C) mission on April 12, 1994. Using a soil dielectric inversion model, the radar data were processed to provide estimates of surface soil dielectric values, which can be equated to volumetric soil moisture content. The soil moisture field along each strip was analyzed for evidence of spatial scaling for scales ranging from 100 to 6400 m. Results suggest that a spatial scaling assumption may not always be an appropriate basis for a downscaling approach. Prospects for the development of a more robust downscaling procedure for soil moisture are discussed.

Crow, Wade T.; Wood, Eric F.; Dubayah, Ralph

2000-01-01

200

Modeling and generating input processes  

SciTech Connect

This tutorial paper provides information relevant to the selection and generation of stochastic inputs to simulation studies. The primary area considered is multivariate but much of the philosophy at least is relevant to univariate inputs as well. 14 refs.

Johnson, M.E.

1987-01-01

201

Demonstration of a sucrose-derived contrast agent for magnetic resonance imaging of the GI tract.  

PubMed

A scaffold bearing eight terminal alkyne groups was synthesized from sucrose, and copies of an azide-terminated Gd-DOTA complex were attached via copper(I)-catalyzed azide-alkyne cycloaddition. The resulting contrast agent (CA) was administered by gavage to C3H mice. Passage of the CA through the gastrointestinal (GI) tract was followed by T1-weighted magnetic resonance imaging (MRI) over a period of 47h, by which time the CA had exited the GI tract. No evidence for leakage of the CA from the GI tract was observed. Thus, a new, orally administered CA for MRI of the GI tract has been developed and successfully demonstrated. PMID:23481651

Martinez, Gary V; Navath, Suryakiran; Sewda, Kamini; Rao, Venkataramanarao; Foroutan, Parastou; Alleti, Ramesh; Moberg, Valerie E; Ahad, Ali M; Coppola, Domenico; Lloyd, Mark C; Gillies, Robert J; Morse, David L; Mash, Eugene A

2013-04-01

202

Nitrogen-doped carbon dots derived from polyvinyl pyrrolidone and their multicolor cell imaging.  

PubMed

Nitrogen-doped carbon dots (N-CDs) with a high quantum yield of 19.6% were prepared by calcining polyvinyl pyrrolidone (PVP, K-30), and then modified with 4,7,10-trioxa-1,13-tridecanediamine. The as-prepared N-CDs exhibited excitation-dependent and pH-sensitive photoluminescence. Transmission electron microscopy and Raman spectra demonstrated the graphitic structure of the N-CDs. Fourier transform infrared spectroscopy and x-ray diffraction studies revealed successful passivation and the presence of hydrophilic groups on the surface. Importantly, such modified quantum dots acted as good multicolor cell imaging probes due to their excellent fluorescent properties, low cytotoxicity and fine dispersity. PMID:24786109

Ding, Hui; Zhang, Peng; Wang, Tian-Yi; Kong, Ji-Lie; Xiong, Huan-Ming

2014-05-23

203

Nitrogen-doped carbon dots derived from polyvinyl pyrrolidone and their multicolor cell imaging  

NASA Astrophysics Data System (ADS)

Nitrogen-doped carbon dots (N-CDs) with a high quantum yield of 19.6% were prepared by calcining polyvinyl pyrrolidone (PVP, K-30), and then modified with 4,7,10-trioxa-1,13-tridecanediamine. The as-prepared N-CDs exhibited excitation-dependent and pH-sensitive photoluminescence. Transmission electron microscopy and Raman spectra demonstrated the graphitic structure of the N-CDs. Fourier transform infrared spectroscopy and x-ray diffraction studies revealed successful passivation and the presence of hydrophilic groups on the surface. Importantly, such modified quantum dots acted as good multicolor cell imaging probes due to their excellent fluorescent properties, low cytotoxicity and fine dispersity.

Ding, Hui; Zhang, Peng; Wang, Tian-Yi; Kong, Ji-Lie; Xiong, Huan-Ming

2014-05-01

204

EU-FP7-iMars: Analysis of Mars Multi-Resolution Images using Auto-Coregistration, Data Mining and Crowd Source Techniques: an overview and a request for scientific inputs.  

NASA Astrophysics Data System (ADS)

Understanding the role of different planetary surface formation processes within our Solar System is one of the fundamental goals of planetary science research. There has been a revolution in planetary surface observations over the last 7 years, especially in 3D imaging of surface shape (down to resolutions of 10cm) and subsequent terrain correction of imagery from orbiting spacecraft. This has led to the ability to be able to overlay different epochs back to the mid-1970s, examine time-varying changes (such as the recent discovery of boulder movement [Orloff et al., 2011] or the sublimation of sub-surface ice revealed by meteoritic impact [Byrne et al., 2009] as well as examine geophysical phenomena, such as surface roughness on different length scales. Consequently we are seeing a dramatic improvement in our understanding of surface formation processes. Since January 2004 the ESA Mars Express has been acquiring global data, especially HRSC stereo (12.5-25m nadir images) with 87% coverage with images ?25m and more than 65% useful for stereo mapping (e.g. atmosphere sufficiently clear). It has been demonstrated [Gwinner et al., 2010] that HRSC has the highest possible planimetric accuracy of ?25m and is well co-registered with MOLA, which represents the global 3D reference frame. HRSC 3D and terrain-corrected image products therefore represent the best available 3D reference data for Mars. NASA began imaging the surface of Mars, initially from flybys in the 1960s with the first orbiter with images ?100m in the late 1970s from Viking Orbiter. The most recent orbiter to begin imaging in November 2006 is the NASA MRO which has acquired surface imagery of around 1% of the Martian surface from HiRISE (at ?20cm) and ?5% from CTX (?6m) in stereo. Unfortunately, for most of these NASA images, especially MGS, MO, VO and HiRISE their accuracy of georeferencing is often worse than the quality of Mars reference data from HRSC. This reduces their value for analysing changes in time series. Within the iMars project (http://i-Mars.eu), a fully automated large-scale processing ('Big Data') solution is being developed to generate the best possible multi-resolution DTM of Mars co-registered to HRSC (50-100m grid) products generated at DLR from CTX (6-20m grid, loc.cit.) and HiRISE (1-3m grids) on a large-scale linux cluster based at MSSL with 224 cores and 0.25 Pb of storage. The HRSC products are employed to provide a geographic reference for all current, future and historical NASA products using automated co-registration based on feature points and initial results will be shown. The metadata already available for all orbital imagery acquired to date, with poor georeferencing information, has been employed to determine the 'sweet spots' which have long time series of measurements with different spatial resolution ranges over the last ?50 years of observations and these will be shown. In 2015, as much of the entire NASA and ESA record of orbital images will be co-registered and the updated georeferencing information employed to generate a time series of terrain relief corrected orthorectified images (ORIs) back to 1977. Web-GIS using OGC protocols will be employed to allow exploration visually of changes of the surface. Data mining processing chains are being developed to search for changes in the Martian surface from 1971-2015 and the output of this data mining will be compared against the results from citizen scientists' measurements in a specialised Zooniverse implementation. Final co-registered data sets will be distributed through both European and US channels in a manner to be decided towards the end of the project. The resultant co-registered image datasets will represent the best possible capture of changes and evolutions in the Martian surface. A workshop is planned to be held during the EGU time period to try to capture scientific input on the relative priorities of different types of changes based on these 'sweet spots'. Acknowledgements: The research leading to these results has received funding from the European

Muller, Jan-Peter; Gwinner, Klaus; van Gasselt, Stephan; Ivanov, Anton; Morley, Jeremy; Houghton, Robert; Bamford, Steven; Yershov, Vladimir; Sidirpoulos, Panagiotis; Kim, Jungrack

2014-05-01

205

Input in Second Language Acquisition.  

ERIC Educational Resources Information Center

This collection of conference papers includes: "When Does Teacher Talk Work as Input?"; "Cultural Input in Second Language Learning"; "Skilled Variation in a Kindergarten Teacher's Use of Foreigner Talk"; "Teacher-Pupil Interaction in Second Language Development"; "Foreigner Talk in the University Classroom"; "Input and Interaction in the…

Gass, Susan M., Ed.; Madden, Carolyn G., Ed.

206

Comparison of retinal thickness by Fourier-domain optical coherence tomography and OCT retinal image analysis software segmentation analysis derived from Stratus optical coherence tomography images  

NASA Astrophysics Data System (ADS)

Purpose: To compare thickness measurements between Fourier-domain optical coherence tomography (FD-OCT) and time-domain OCT images analyzed with a custom-built OCT retinal image analysis software (OCTRIMA). Methods: Macular mapping (MM) by StratusOCT and MM5 and MM6 scanning protocols by an RTVue-100 FD-OCT device are performed on 11 subjects with no retinal pathology. Retinal thickness (RT) and the thickness of the ganglion cell complex (GCC) obtained with the MM6 protocol are compared for each early treatment diabetic retinopathy study (ETDRS)-like region with corresponding results obtained with OCTRIMA. RT results are compared by analysis of variance with Dunnett post hoc test, while GCC results are compared by paired t-test. Results: A high correlation is obtained for the RT between OCTRIMA and MM5 and MM6 protocols. In all regions, the StratusOCT provide the lowest RT values (mean difference 43 +/- 8 ?m compared to OCTRIMA, and 42 +/- 14 ?m compared to RTVue MM6). All RTVue GCC measurements were significantly thicker (mean difference between 6 and 12 ?m) than the GCC measurements of OCTRIMA. Conclusion: High correspondence of RT measurements is obtained not only for RT but also for the segmentation of intraretinal layers between FD-OCT and StratusOCT-derived OCTRIMA analysis. However, a correction factor is required to compensate for OCT-specific differences to make measurements more comparable to any available OCT device.

Tátrai, Erika; Ranganathan, Sudarshan; Ferencz, Mária; Debuc, Delia Cabrera; Somfai, Gábor Márk

2011-05-01

207

Deriving Atmospheric Properties and Escape Rates from MAVEN's Imaging UV Spectrograph (IUVS)  

NASA Astrophysics Data System (ADS)

MAVEN (Mars Volatile and Atmosphere EvolutioN) is a Mars Scout mission being readied for launch in November 2013. The key hardware and management partners are University of Colorado, Goddard Space Flight Center, University of California at Berkeley, Lockheed Martin, and the Jet Propulsion Laboratory. MAVEN carries a powerful suite of fields and particles instruments and a sophisticated remote sensing instrument, the Imaging UltraViolet Spectrograph (IUVS). This presentation begins by describing IUVS' science goals, instrument design, operational approach and data analysis strategy. IUVS supports the top-level MAVEN science goals: measure the present state of the atmosphere, observe its response to varying solar stimuli, and use the information to estimate loss from Mars' atmosphere over time. The instrument operates at low spectral resolution spanning the FUV and MUV ranges in separate channels, and at high resolution around the hydrogen Lyman alpha line to measure the D/H ratio in the upper atmosphere. MAVEN carries the instrument on an Articulated Payload Platform which orients the instrument for optimal observations during four segments of its 4.5 hr elliptical orbit. During periapse passage, IUVS uses a scan mirror to obtain vertical profiles of emissions from the atmosphere and ionosphere. Around apoapse, the instrument builds up low-resolution images of the atmosphere at multiple wavelengths. In between, the instrument measures emissions from oxygen, hydrogen and deuterium in the corona. IUVS also undertakes day-long stellar occultation campaigns at 2 month intervals, to measure the state of the atmosphere at altitudes below the airglow layer and in situ sampling. All data will be pipeline-processed from line brightnesses to column abundances, local densities and global 3-D maps. The focus of the presentation is development of these automatic processing algorithms and the data products they will provide to the Mars community through the PDS Atmospheres Node. The combined results from all instruments on ion and neutral escape will bear on the central question of the history of Mars' atmosphere and climate history. This work has been supported by NASA's MAVEN mission.

Schneider, Nicholas M.; IUVS Science Team

2013-10-01

208

Diurnal, Seasonal, and Interannual Variations of Cloud Properties Derived for CERES From Imager Data  

NASA Technical Reports Server (NTRS)

Simultaneous measurement of the radiation and cloud fields on a global basis is a key component in the effort to understand and model the interaction between clouds and radiation at the top of the atmosphere, at the surface, and within the atmosphere. The NASA Clouds and Earth s Radiant Energy System (CERES) Project, begun in 1998, is meeting this need. Broadband shortwave (SW) and longwave radiance measurements taken by the CERES scanners at resolutions between 10 and 20 km on the Tropical Rainfall Measuring Mission (TRMM), Terra, and Aqua satellites are matched to simultaneous retrievals of cloud height, phase, particle size, water path, and optical depth OD from the TRMM Visible Infrared Scanner (VIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Besides aiding the interpretation of the broadband radiances, the CERES cloud properties are valuable for understanding cloud variations at a variety of scales. In this paper, the resulting CERES cloud data taken to date are averaged at several temporal scales to examine the temporal and spatial variability of the cloud properties on a global scale at a 1 resolution.

Minnis, Patrick; Young, David F.; Sun-Mack, Sunny; Trepte, Qing Z.; Chen, Yan; Brown, Richard R.; Gibson, Sharon; Heck, Patrick W.

2004-01-01

209

Vitamin b1 derived blue and green fluorescent carbon nanoparticles for cell-imaging application.  

PubMed

A carbon-based fluorescent nanoparticle is considered to be a new generation nontoxic nanoprobe suitable for various bioimaging and sensing applications. However, the synthesis of such a high-quality nanoparticle is challenging, and its application potential is mostly unexplored. Here we report a vitamin B1 carbonization-based approach for blue and green fluorescent carbon nanoparticles of <10 nm size with a fluorescence quantum of up to 76%. We found that carbonization of vitamin B1 in the presence of phosphate salt at ?90-130 °C for about 2 h produces highly fluorescent carbon nanoparticles of 1-6 nm size. The particle size and fluorescence property can be controlled by varying the reaction temperature and nature of phosphate salt. Elemental analysis shows the incorporation of a large percentage (up to 48 wt %) of other elements (such as nitrogen, oxygen, phophorus, and sulfur) in the carbon matrix. The chemical structure of vitamin B1 (thiamine) is unique in a sense that it consists of a large number of heteroatoms along with unsaturated bonds and offers low-temperature carbonization with the formation of a nanoparticle having an optimum ratio of sp(2) and sp(3) carbon atoms. These carbon nanoparticles have high colloidal stability and stable fluorescence and have been used as fluorescent imaging probes. PMID:24697797

Bhunia, Susanta Kumar; Pradhan, Nibedita; Jana, Nikhil R

2014-05-28

210

A structural model of the orthorhombic Ga7Mn5 derived from its HREM image  

PubMed

The base-centered orthorhombic approximant Ga7Mn5 (a = 4.547(6) nm, b = 1.256(9) nm, c = 1.482(1) nm) consisting of flattened hexagon and concave octagon (called "crown" in this paper) subunits shown by high-resolution electron microscopy (HREM) was found to coexist with the Ga-Mn decagonal quasicrystal in the Ga58Mn42 alloy. The atomic sites in the flattened hexagon subunit have been deduced recently from a structural study of the orthorhombic Ga-Mn (1/1,1/1) approximant that consists only of the hexagon subunits. Similarly, the atomic sites in the crown subunit have been deduced from another orthorhombic Ga-Mn (2/1,1/1) approximant consisting only of the crown subunits. A structural model of the orthorhombic Ga7Mn5 can thus be constructed from these structural subunits. There are 332 Ga atoms and 232 Mn atoms in a unit cell, with a composition of Mn41.2Ga58.8, satisfying the symmetry of the space group Bmm2. The simulated electron diffraction patterns, [010] HREM images, and X-ray powder diffraction pattern based on this structural model agrees mainly with the experimental observations. PMID:10831289

Wu; Kuo

2000-10-01

211

Dynamics of polar boundary of the auroral oval derived from the IMAGE satellite data  

NASA Astrophysics Data System (ADS)

Based on a new database on positions of the auroral oval boundaries including measurements made by the IMAGE satellite in 2000-2002 with correct determination of the glow boundaries, statistical estimations of the latitudinal position of the polar cap boundary (PCB) are obtained depending on the IMF B y and B z , and the PCB evolution during a magnetic storm is analyzed. At zero IMF in the noon (midnight) sector, PCB is located approximately at 80° (76°) CGMLat. The PCB displacement along the noon-midnight meridian is controlled by the IMF B z , and in the noon (midnight) sector it is equal to 0.45° (0.15°) CGMLat when B z changes by 1 nT. The PCB displacement along the dawn-dusk meridian depends on the IMF B y , and it equals 0.1° CGMLat when B y changes by 1 nT. Accordingly, the north polar cap as a whole is shifted to the dawn (dusk) side at B y > 0 ( B y <0). After northward turn of the IMF during the storm's recovery phase, the PCB on the dayside is shifted to the north practically without time delay. The night boundary requires 25 h or more in order to be shifted to the pole to a latitude corresponding to B z > 0.

Lukianova, R.; Kozlovsky, A.

2013-01-01

212

Toxicological evaluation of a rotenone derivative in rodents for clinical myocardial perfusion imaging.  

PubMed

Myocardial perfusion scintigraphy is a valuable clinical tool for assessing coronary blood flow deficits in patients. We recently synthesized a new iodinated compound ((123)I-CMICE-013) based on rotenone and showed that it has excellent performance as a radiotracer for myocardial perfusion imaging. Here, we describe the cellular toxicity and subacute toxicity of CMICE-013 in rats. Cultured hepatocytes displayed sensitivity to rotenone but not CMICE-013 at equimolar concentrations. Following i.v. injection of CMICE-013 for 14 days, body weight, ambulation, behavior, grooming, guarding (abdominal, muscular), pale conjunctivae, and food intake were observed. Biochemical, hematological, and histopathological changes in tissues (heart, liver, kidney, spleen, lung, and brain) and echocardiography at pre- and post-dosing were also examined. All animals responded well to the daily injections of CMICE-013 and showed no mortality or adverse reactions with respect to the parameters above. Subacute i.v. injections at high- (5 ?g/kg) and low (1 ?g/kg)-dose levels did not result in any significant changes to either biochemical or hematological parameters and no detectable changes in histopathology compared to the vehicle or untreated animals. Echocardiographic analyses, including the measurements of cardiac function and anatomy (wall thickness, left atrial size, and left ventricular mass), were not different at pre- versus post-dose measures and were not different compared to the vehicle or untreated animals. Our observations in small animals reveal that CMICE-013 induces minimal toxicity when delivered intravenously for 14 days. PMID:24395712

Fernando, Pasan; Yan, Xuxu; Lockwood, Julia; Duan, Yin; Wei, Lihui; Glenn Wells, R; Bensimon, Corinne; Mullett, Wayne M; Ruddy, Terrence

2014-06-01

213

Emplacement of the 1907 Mauna Loa Basalt Flow as Derived From Precision Topography and Satellite Imaging  

NASA Astrophysics Data System (ADS)

The January 1907 eruption from the southwest rift zone of Mauna Loa produced a very substantial lava flow field. Satellite images and Differential Global Positioning System (DGPS) topographic data, combined with observations and photographs from the field, provide a new perspective on the 1907 eruption. Boundaries of the flow field from the satellite data, along with field measurements of flow thickness, indicate an area of 25.1 square km and a volume of 86.6 million cubic m. The eastern lobe of the flow field covers and area of 13.1 square km, with a volume of 55.0 million cubic m, and was emplaced with an average effusion rate of 119 cubic m per sec (for the highest one-half of the lobe). Ten DGPS topographic profiles across the eastern lobe aid in distinguishing the characteristics of, and transitions between, three specific zones identified during the emplacement of the 1984 Mauna Loa flow. Several subdivisions have been built directly on top of, or adjacent to, the 1907 lava flow. The strong likelihood of future eruptions from the Mauna Loa southwest rift zone make these housing developments of particular importance for assessment of potential volcanic hazards. The flow should be useful as an analog for interpreting lava flow features on other planets.

Zimbelman, J. R.; Garry, W. B.; Johnston, A. K.; Williams, S. H.

2006-12-01

214

Biodistribution of mesenchymal stem cell-derived extracellular vesicles in a model of acute kidney injury monitored by optical imaging  

PubMed Central

Mesenchymal stem cells (MSCs) contribute to the recovery of tissue injury, providing a paracrine support. Cell-derived extracellular vesicles (EVs), carrying membrane and cytoplasmatic constituents of the cell of origin, have been described as a fundamental mechanism of intercellular communication. We previously demonstrated that EVs derived from human MSCs accelerated recovery following acute kidney injury (AKI) in vivo. The aim of the present study was to investigate the biodistribution and the renal localization of EVs in AKI. For this purpose, two methods for EV labeling suitable for in vivo tracking with optical imaging (OI), were employed using near infrared (NIR) dye (DiD): i) labeled EVs were generated by MSCs pre-incubated with NIR dye and collected from cell supernatants; ii) purified EVs were directly labeled with NIR dye. EVs obtained with these two procedures were injected intravenously (i.v.) into mice with glycerol-induced AKI and into healthy mice to compare the efficacy of the two labeling methods for in vivo detection of EVs at the site of damage. We found that the labeled EVs accumulated specifically in the kidneys of the mice with AKI compared with the healthy controls. After 5 h, the EVs were detectable in whole body images and in dissected kidneys by OI with both types of labeling procedures. The directly labeled EVs showed a higher and brighter fluorescence compared with the labeled EVs produced by cells. The signal generated by the directly labeled EVs was maintained in time, but provided a higher background than that of the labeled EVs produced by cells. The comparison of the two methods indicated that the latter displayed a greater specificity for the injured kidney.

GRANGE, CRISTINA; TAPPARO, MARTA; BRUNO, STEFANIA; CHATTERJEE, DEVASIS; QUESENBERRY, PETER J.; TETTA, CIRO; CAMUSSI, GIOVANNI

2014-01-01

215

Modeling Recognition Memory Using the Similarity Structure of Natural Input  

ERIC Educational Resources Information Center

The natural input memory (NAM) model is a new model for recognition memory that operates on natural visual input. A biologically informed perceptual preprocessing method takes local samples (eye fixations) from a natural image and translates these into a feature-vector representation. During recognition, the model compares incoming preprocessed…

Lacroix, Joyca P. W.; Murre, Jaap M. J.; Postma, Eric O.; van den Herik, H. Jaap

2006-01-01

216

Photometric parameter maps of the Moon derived from LROC WAC images  

NASA Astrophysics Data System (ADS)

Spatially resolved photometric parameter maps were computed from 21 months of Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) images. Due to a 60° field-of-view (FOV), the WAC achieves nearly global coverage of the Moon each month with more than 50% overlap from orbit-to-orbit. From the repeat observations at various viewing and illumination geometries, we calculated Hapke bidirectional reflectance model parameters [1] for 1°x1° "tiles" from 70°N to 70°S and 0°E to 360°E. About 66,000 WAC images acquired from February 2010 to October 2011 were converted from DN to radiance factor (I/F) though radiometric calibration, partitioned into gridded tiles, and stacked in a time series (tile-by-tile method [2]). Lighting geometries (phase, incidence, emission) were computed using the WAC digital terrain model (100 m/pixel) [3]. The Hapke parameters were obtained by model fitting against I/F within each tile. Among the 9 parameters of the Hapke model, we calculated 3 free parameters (w, b, and hs) by setting constant values for 4 parameters (Bco=0, hc=1, ?, ?=0) and interpolating 2 parameters (c, Bso). In this simplification, we ignored the Coherent Backscatter Opposition Effect (CBOE) to avoid competing CBOE and Shadow Hiding Opposition Effect (SHOE). We also assumed that surface regolith porosity is uniform across the Moon. The roughness parameter (?) was set to an averaged value from the equator (× 3°N). The Henyey-Greenstein double lobe function (H-G2) parameter (c) was given by the 'hockey stick' relation [4] (negative correlation) between b and c based on laboratory measurements. The amplitude of SHOE (Bso) was given by the correlation between w and Bso at the equator (× 3°N). Single scattering albedo (w) is strongly correlated to the photometrically normalized I/F, as expected. The c shows an inverse trend relative to b due to the 'hockey stick' relation. The parameter c is typically low for the maria (0.08×0.06) relative to the highlands (0.47×0.16). Since c controls the fraction of backward/forward scattering in H-G2, lower c for the maria indicates more forward scattering relative to the highlands. This trend is opposite to what was expected because darker particles are usually more backscattering. However, the lower albedo of the maria is due to the higher abundance of ilmenite, which is an opaque mineral that scatters all of the light by specular reflection from the its surface. If their surface facets are relatively smooth the ilmenite particles will be forward scattering. Other factors (e.g. grain shape, grain size, porosity, maturity) besides the mineralogy might also be affecting c. The angular-width of SHOE (hs) typically shows lower values (0.047×0.02) for the maria relative to the highlands (0.074×0.025). An increase in hs for the maria theoretically suggests lower porosity or a narrower grain size distribution [1], but the link between actual materials and hs is not well constrained. Further experiments using both laboratory and spacecraft observations will help to unravel the photometric properties of the surface materials of the Moon. [1] Hapke, B.: Cambridge Univ. Press, 2012. [2] Sato, H. et al.: 42nd LPSC, abstract #1974, 2011. [3] Scholten, F. et al.: JGR, 117, E00H17, 2012. [4] Hapke, B.: Icarus, 221(2), p1079-1083, 2012.

Sato, H.; Robinson, M. S.; Hapke, B. W.; Denevi, B. W.; Boyd, A. K.

2013-12-01

217

Algal Accessory Pigment Detection Using AVIRIS Image-Derived Spectral Radiance Data  

NASA Technical Reports Server (NTRS)

Visual and derivative analyses of AVIRIS spectral data can be used to detect algal accessory pigments in aquatic communities. This capability extends the use of remote sensing for the study of aquatic ecosystems by allowing detection of taxonomically significant pigment signatures which yield information about the type of algae present. Such information allows remote sensing-based assessment of aquatic ecosystem health, as in the detection of nuisance blooms of cyanobacteria or toxic blooms of dinoflagellates. Remote sensing of aquatic systems has traditionally focused on quantification of chlorophyll a, a photoreactive (and light-harvesting) pigment which is common to all algae as well as cyanobacteria (bluegreen algae). Due to the ubiquitousness of this pigment within algae, chl a is routinely measured to estimate algal biomass both during ground-truthing and using various airborne or satellite based sensors, including AVIRIS. Within the remote sensing and aquatic sciences communities, ongoing research has been performed to detect algal accessory pigments for assessment of algal population composition. This research is based on the fact that many algal accessory pigments are taxonomically significant, and all are spectrally unique. Aquatic scientists have been refining pigment analysis techniques, primarily high performance liquid chromatography, or HPLC, to detect specific pigments as a time-saving alternative to individual algal cell identifications and counts. Remote sensing scientists are investigating the use of pigment signatures to construct pigment libraries analogous to mineral spectral libraries used in geological remote sensing applications. The accessory pigment approach has been used successfully in remote sensing using data from the Thematic Mapper, low-altitude, multiple channel scanners, field spectroradiometers and the AVIRIS hyperspectral scanner. Due to spectral and spatial resolution capabilities, AVIRIS is the sensor of choice for such studies. We present here our results on detection of algal accessory pigments using AVIRIS data.

Richardson, Laurie L.; Ambrosia, Vincent G.

1996-01-01

218

Physical Conditions in the Central Parsec Derived from Mid-Infrared Imaging Photometry  

NASA Technical Reports Server (NTRS)

Array camera images of the central 1 parsec of the Galactic Center at eight mid-infrared wavelengths between 4.8 and 20.0 microns with approximately 1 arcsec resolution are used to model the temperature, opacity and bolometric luminosity distributions of the emitting dust in the central parsec, and the extinction in the line of sight. We use the results to discriminate between two mechanisms for heating the dust: heating by radiation from a "central engine" (possibly a massive black hole associated with Sgr A*), or internal heating by luminous stars embedded in or among the dust clouds. The temperature and opacity distributions are consistent with the presence of self-luminous objects imbedded at prominent the IRS source positions. However, temperatures on the northern ann and east-west bar are highest along the inner flank of those structures surrounding the central cavity, while the dust opacity peaks further out from the central cavity. The warm inner ridge suggests heating by centrally located concentrated luminous sources, including IRS3 and IRS7. The of the model results are compared with the distributions of the various stellar populations in the central parsec. There is evidence for physical interaction between the warm emitting dust and luminous stars, including dozens of hot He1 emission line stars and B[] stars. The combined contributions of embedded stars at the IRS source positions and the luminous stars distributed throughout Sgr A West can account for the temperature enhancements and the luminosity distribution in the central parsec computed by the model.

Gezari, Dan; Dwek, Eli; Varosi, Frank

2002-01-01

219

Magnetic-resonance-imaging-derived indices for the normalization of left ventricular morphology by body size.  

PubMed

Scaling left ventricular (LV) mass and other cardiac dimensions to account for individual body size is important. The traditional method of simple ratio scaling using, for example, body surface area (BSA) assumes a linear and proportional relationship and accurate measurement of both LV mass and BSA. These assumptions can be questioned; hence, we examined the appropriateness of methods and different indices using highly accurate magnetic resonance imaging scans. Cardiac and whole-body scans were performed in 172 young, healthy, male subjects (age range, 17-28 years) to assess LV mass, volume, linear dimensions, lean body mass and fat mass. Height, body mass and BSA were determined anthropometrically. Relationships were examined for linearity and closeness of fit using log-log least-squares linear regression to determine the slope exponent b (where 1.0 indicates linearity). The relationship between LV mass and lean body mass (b=.90+/-.15; r(2)=.66) was linear and geometrically consistent. This was also the case for LV end-diastolic volume (b=.70), although the confidence intervals were broader (+/-0.32) and the r(2) (.31) smaller. The relationships between LV mass, volume and other variables were generally not linear or geometrically consistent. LV linear dimensions did not demonstrate any linear relationships, and in particular, those with BSA were extremely poor (r(2)=.02-.09). In summary, the traditional scaling of LV measurements to BSA does not remove the influence of body size and other techniques should be considered. Lean body mass was the most appropriate variable for simple indexing of LV mass. No body size variable had a linear and proportional relationship with LV linear dimensions, and the use of simple ratio scaling for these is seriously questioned. PMID:18687545

George, Keith P; Birch, Karen M; Pennell, Dudley J; Myerson, Saul G

2009-02-01

220

A Kalman Filter Based Tracking Scheme with Input Estimation  

Microsoft Academic Search

Beginning with the derivation of a least squares estimator that yields an estimate of the acceleration input vector, this paper first develops a detector for sensing target maneuvers and then develops the combination of the estimator, detector, and a \\

Y. T. Chan; A. G. C. Hu; J. B. Plant

1979-01-01

221

Susceptibility of the wild-derived inbred CAST/Ei mouse to infection by orthopoxviruses analyzed by live bioluminescence imaging.  

PubMed

Classical inbred mice are extensively used for virus research. However, we recently found that some wild-derived inbred mouse strains are more susceptible than classical strains to monkeypox virus. Experiments described here indicated that the 50% lethal dose of vaccinia virus (VACV) and cowpox virus (CPXV) were two logs lower in wild-derived inbred CAST/Ei mice than classical inbred BALB/c mice, whereas there was little difference in the susceptibility of the mouse strains to herpes simplex virus. Live bioluminescence imaging was used to follow spread of pathogenic and attenuated VACV strains and CPXV virus from nasal passages to organs in the chest and abdomen of CAST/Ei mice. Luminescence increased first in the head and then simultaneously in the chest and abdomen in a dose-dependent manner. The spreading kinetics was more rapid with VACV than CPXV although the peak photon flux was similar. These data suggest advantages of CAST/Ei mice for orthopoxvirus studies. PMID:24418545

Americo, Jeffrey L; Sood, Cindy L; Cotter, Catherine A; Vogel, Jodi L; Kristie, Thomas M; Moss, Bernard; Earl, Patricia L

2014-01-20

222

Synthesis and Preliminary Evaluation of a 2-Oxoquinoline Carboxylic Acid Derivative for PET Imaging the Cannabinoid Type 2 Receptor.  

PubMed

Cannabinoid receptor subtype 2 (CB2) has been shown to be up-regulated in activated microglia and therefore plays an important role in neuroinflammatory and neurodegenerative diseases such as multiple sclerosis, amyotrophic lateral sclerosis and Alzheimer's disease. The CB2 receptor is therefore considered as a very promising target for therapeutic approaches as well as for imaging. A promising 2-oxoquinoline derivative designated KP23 was synthesized and radiolabeled and its potential as a ligand for PET imaging the CB2 receptor was evaluated. [11C]KP23 was obtained in 10%-25% radiochemical yield (decay corrected) and 99% radiochemical purity. It showed high stability in phosphate buffer, rat and mouse plasma. In vitro autoradiography of rat and mouse spleen slices, as spleen expresses a high physiological expression of CB2 receptors, demonstrated that [11C]KP23 exhibits specific binding towards CB2. High spleen uptake of [11C]KP23 was observed in dynamic in vivo PET studies with Wistar rats. In conclusion, [11C]KP23 showed promising in vitro and in vivo characteristics. Further evaluation with diseased animal model which has higher CB2 expression levels in the brain is warranted. PMID:24662272

Mu, Linjing; Slavik, Roger; Müller, Adrienne; Popaj, Kasim; Cermak, Stjepko; Weber, Markus; Schibli, Roger; Krämer, Stefanie D; Ametamey, Simon M

2014-01-01

223

A new approach of the rupture process of the great earthquakes using images derived from hydroacoustic or infrasound array processing  

NASA Astrophysics Data System (ADS)

The study of the source of major earthquakes is of great interest for the scientific community because the parameters derived from have a major importance for the rapid estimation of associated effects (destruction or tsunami). In the framework of these studies, we have identified the array processing as a modern tool that can provide vital information on the geometry and the kinematics of the rupture. Thanks to the various technologies implied in the CTBT, we have brought these studies in the field of seismology, infrasound and hydroacoustic. These different approaches have resulted in either a direct visualization of the rupture thanks to the analysis of variations of azimuth with time of direct waves from the source or indirectly by obtaining the scope of radiation pattern of surface waves. This type of image is very innovative because it allows provide information on geographic areas which are not instrumented. We show multiple images of treatment PMCC (Progressive Multi Channel Correlation) associated with different major earthquakes as Sumatra Mw=9.3, Nias Mw=8.7, Kokoxoli Mw=7.8, Tohoku Mw=9.0 and how we can constrain the rupture of these events. These studies show the interest of the CTBT network and more precisely the dense arrays of sensors. These arrays offer the unique opportunity for a multi-technological approach of the seismic source and, perhaps, ultimately, the improvement of warning systems.

Guilbert, J.; Le Pichon, A.; Vergoz, J.; Sèbe, O.

2012-04-01

224

Analysis and minimization of the input current ripple of Interleaved Boost Converter  

Microsoft Academic Search

This paper proposes a new method to quantify the input current ripple cancellation effect of Interleaved Boost Converter (IBC) and derives an universal formula to quantify the input current ripple waveform of IBC. The practical factors that affect the input current ripple are presented and the comprehensive design of the input current ripple minimization of IBC is discussed based on

Zhang Saijun

2012-01-01

225

Characterization of a far-red analog of ghrelin for imaging GHS-R in P19-derived cardiomyocytes.  

PubMed

Ghrelin and its receptor, the growth hormone secretagogue receptor (GHS-R), are expressed in the heart, and may function to promote cardiomyocyte survival, differentiation and contractility. Previously, we had generated a truncated analog of ghrelin conjugated to fluorescein isothiocyanate for the purposes of determining GHS-R expression in situ. We now report the generation and characterization of a far-red ghrelin analog, [Dpr(3)(octanoyl), Lys(19)(Cy5)]ghrelin (1-19), and show that it can be used to image changes in GHS-R in developing cardiomyocytes. We also generated the des-acyl analog, des-acyl [Lys(19)(Cy5)]ghrelin (1-19) and characterized its binding to mouse heart sections. Receptor binding affinity of Cy5-ghrelin as measured in HEK293 cells overexpressing GHS-R1a was within an order of magnitude of that of fluorescein-ghrelin and native human ghrelin, while the des-acyl Cy5-ghrelin did not bind GHS-R1a. Live cell imaging in HEK293/GHS-R1a cells showed cell surface labeling that was displaced by excess ghrelin. Interestingly, Cy5-ghrelin, but not the des-acyl analog, showed concentration-dependent binding in mouse heart tissue sections. We then used Cy5-ghrelin to track GHS-R expression in P19-derived cardiomyocytes. Live cell imaging at different time points after DMSO-induced differentiation showed that GHS-R expression preceded that of the differentiation marker aMHC and tracked with the contractility marker SERCA 2a. Our far-red analog of ghrelin adds to the tools we are developing to map GHS-R in developing and diseased cardiac tissues. PMID:24468548

Douglas, Gregory A F; McGirr, Rebecca; Charlton, Carlie L; Kagan, Dov B; Hoffman, Lisa M; Luyt, Leonard G; Dhanvantari, Savita

2014-04-01

226

Intermediate inputs and economic productivity.  

PubMed

Many models of economic growth exclude materials, energy and other intermediate inputs from the production function. Growing environmental pressures and resource prices suggest that this may be increasingly inappropriate. This paper explores the relationship between intermediate input intensity, productivity and national accounts using a panel dataset of manufacturing subsectors in the USA over 47 years. The first contribution is to identify sectoral production functions that incorporate intermediate inputs, while allowing for heterogeneity in both technology and productivity. The second contribution is that the paper finds a negative correlation between intermediate input intensity and total factor productivity (TFP)--sectors that are less intensive in their use of intermediate inputs have higher productivity. This finding is replicated at the firm level. We propose tentative hypotheses to explain this association, but testing and further disaggregation of intermediate inputs is left for further work. Further work could also explore more directly the relationship between material inputs and economic growth--given the high proportion of materials in intermediate inputs, the results in this paper are suggestive of further work on material efficiency. Depending upon the nature of the mechanism linking a reduction in intermediate input intensity to an increase in TFP, the implications could be significant. A third contribution is to suggest that an empirical bias in productivity, as measured in national accounts, may arise due to the exclusion of intermediate inputs. Current conventions of measuring productivity in national accounts may overstate the productivity of resource-intensive sectors relative to other sectors. PMID:23359736

Baptist, Simon; Hepburn, Cameron

2013-03-13

227

Serial Input Output  

SciTech Connect

Serial Input/Output (SIO) is designed to be a long term storage format of a sophistication somewhere between simple ASCII files and the techniques provided by inter alia Objectivity and Root. The former tend to be low density, information lossy (floating point numbers lose precision) and inflexible. The latter require abstract descriptions of the data with all that that implies in terms of extra complexity. The basic building blocks of SIO are streams, records and blocks. Streams provide the connections between the program and files. The user can define an arbitrary list of streams as required. A given stream must be opened for either reading or writing. SIO does not support read/write streams. If a stream is closed during the execution of a program, it can be reopened in either read or write mode to the same or a different file. Records represent a coherent grouping of data. Records consist of a collection of blocks (see next paragraph). The user can define a variety of records (headers, events, error logs, etc.) and request that any of them be written to any stream. When SIO reads a file, it first decodes the record name and if that record has been defined and unpacking has been requested for it, SIO proceeds to unpack the blocks. Blocks are user provided objects which do the real work of reading/writing the data. The user is responsible for writing the code for these blocks and for identifying these blocks to SIO at run time. To write a collection of blocks, the user must first connect them to a record. The record can then be written to a stream as described above. Note that the same block can be connected to many different records. When SIO reads a record, it scans through the blocks written and calls the corresponding block object (if it has been defined) to decode it. Undefined blocks are skipped. Each of these categories (streams, records and blocks) have some characteristics in common. Every stream, record and block has a name with the condition that each stream, record or block name must be unique in its category (i.e. all streams must have different names, but a stream can have the same name as a record). Each category is an arbitrary length list which is handled by a 'manager' and there is one manager for each category.

Waite, Anthony; /SLAC

2011-09-07

228

Selection of weighting factors for quantification of PET radioligand binding using simplified reference tissue models with noisy input functions  

NASA Astrophysics Data System (ADS)

Input function noise contributes to model-predicted values and should be accounted for during parameter estimation. This problem has been examined in the context of PET data analysis using a noisy image-derived arterial input function. Huesman and Mazoyer (1987 Phys. Med. Biol 32 1569-79) incorporated the effect of error in the measured input function into the objective function and observed a subsequent improvement in the accuracy of parameters estimated from a kinetic model of cardiac blood flow. Such a treatment has not been applied to the reference region models commonly used to analyze dynamic positron emission tomography data with receptor-ligand tracers. Here, we propose a strategy for selection of weighting factors that accounts for noise in the reference region input function and test the method on two common formulations of the simplified reference tissue model (SRTM). We present a simulation study which demonstrates that the proposed weighting approach improves the accuracy of estimated binding potential at high noise levels and when the reference tissue and target regions of interest are of comparable size. In the second simulation experiment, we show that using a small, homogeneous reference tissue with our weighting technique may have advantages over input functions derived from a larger (and thus less noisy), heterogeneous region with conventional weighting. A comparative analysis of clinical [11C]flumazenil data found a small but significant increase in estimated binding potential when using the proposed weighting method, consistent with the finding of reduced negative bias in our simulation study. The weighting strategy described here accounts for noise in the reference region input function and may improve the performance of the SRTM in applications where data are noisy and the reference region is relatively small. This technique may offer similar benefits to other models using reference region inputs, particularly those derived from the SRTM.

Normandin, M. D.; Koeppe, R. A.; Morris, E. D.

2012-02-01

229

Atmospheric Motion Vectors Derived via a New Nested Tracking Algorithm Developed for the GOES-R Advanced Baseline Imager (ABI)  

NASA Astrophysics Data System (ADS)

A new Atmospheric Motion Vector (AMV) nested tracking algorithm has been developed for the Advanced Baseline Imager (ABI) to be flown on NOAA's future GOES-R satellite. The algorithm has been designed to capture the dominant motion in each target scene from a family of local motion vectors derived for each target scene. Capturing this dominant motion is achieved through use of a two-dimensional clustering algorithm that segregates local displacements into clusters. The dominant motion is taken to be the average of the local displacements of points belonging to the largest cluster. This approach prevents excessive averaging of motion that may be occurring at multiple levels or at different scales that can lead to a slow speed bias and a poor quality AMV. A representative height is assigned to the dominant motion vector through exclusive use of cloud heights from pixels belonging to the largest cluster. This algorithm has been demonstrated to significantly improve the slow speed bias typically observed in AMVs derived from satellite imagery. Meteosat SEVERI imagery is serving as an important GOES-R ABI proxy data source for the development, testing, and validation of the GOES-R AMV algorithms given its similarities (spectral coverage, pixel resolution, and scanning rate) and performance (spectral noise, navigation/registration) to the future GOES-R ABI. The new GOES-R AMV algorithm is also being applied to the instrumentation on the current operational GOES series of satellites and is expected to replace the heritage AMV algorithm being used in NESDIS operations today. Plans at NOAA/NESDIS also include using the new GOES-R AMV algorithm to generate AMVs from the future VIIRS instrument on the NPP satellite. Details of the GOES-R ABI AMV algorithm and the validation results will be presented and discussed.

Daniels, J.; Bresky, W.; Wanzong, S.; Velden, C.

2012-12-01

230

A Tc-99m labeled laminin derived peptide, Tc-99m-YIGSR for thrombus specific imaging  

SciTech Connect

Laminin derived adhesive peptides were studied as potential agents for thrombus specific imaging. Using a novel peptide Tc-99m labeling method studies were performed in vitro using human whole blood clots and platelets, and in vivo scintigraphy in animals with experimental thrombi. Aliquots of 0.1 ml human blood were placed in inclined Petri dishes until clot was well formed. Clots were rinsed 3x with phosphate buffer and 10 {mu}Ci Tc-99m YIGSR II was added. After incubation at room temperature for 1 hr, clots were again washed 3x. Residual activity was measured. Platelets were harvested using routine methods and incubated with Tc-99m YIGSR II, washed and assayed. Blocking experiments using cold YIGSR II showed that the Tc-99m labeled peptide preparation YIGSR II binds specifically and selectively to clot and platelets as compared to control experiments using nonspecific human Tc-99m IgG. Tissue distribution studies showed rapid blood clearance, urinary excretion and to a lesser degree GI tract excretion. Tc-99m YIGSR II was lower in all organs except kidneys compared to Tc-99m 50 H.19, Tc-99m IgG and Tc-99m YIGSR I. Tc-99m-YIGSR II consistently visualized thrombi within 30 min p.i. In vivo scintigraphic (thrombus/contralateral side) ratio was 3:1 and ex vivo direct counting (thrombosed to nonthrombosed vessel segment) was 5.4: 1. Compared to monoclonal antibodies peptide preparations are non- or minimally immunogenic, preparation is probably less expensive and there is also less danger of viral DNA contamination. These considerations and our data indicate that the Tc-99m-YIGSR II peptide has significant potential as a thrombus imaging agent.

Wang, G.J.; Oster, Z.H.; Som, P. [Brookhaven National Lab., Upton, NY (United States)] [and others

1994-05-01

231

Deriving soil function maps to assess related ecosystem services using imaging spectroscopy in the Lyss agricultural area, Switzerland  

NASA Astrophysics Data System (ADS)

Soils play an important role in the benefits offered by ecosystems services. In densely populated Switzerland soils are a scarce resource, with high pressure on services ranging from urban expansion to over-utilization. Key change drivers include erosion, soil degradation, land management change and (chemical) pollution, which should be taken into consideration. Therefore there is an emerging need for an integrated, sustainable and efficient system assessing the management of soil and land as a resource. The use of remote sensing can offer spatio-temporal and quantitative information of extended areas. In particular imaging spectroscopy has shown to perfectly complement existing sampling schemes as secondary information for digital soil mapping. Although only the upper-most layer of soil interacts with light when using reflectance spectroscopy, it still can offer valuable information that can be utilized by farmers and decision makers. Fully processed airborne imaging spectrometer data from APEX as well as land cover classification for the agricultural area in Lyss were available. Based on several spectral analysis methods we derived multiple soil properties, including soil organic matter, soil texture, and mineralogy; complemented by vegetation parameters, including leaf area index, chlorophyll content, pigment distribution, and water content. The surface variables were retrieved using a combination of index-based and physically-based retrievals. Soil properties in partly to fully vegetated areas were interpolated using regression kriging based methods. This allowed the continuous assessment of potential soil functions as well as non-contiguous maps of abundances of combined soil and vegetation parameters. Based on a simple regression model we could make a rough estimate of ecosystem services. This provided the opportunity to look at the differences between the interpolated soil function maps and the non-contiguous (but combined) vegetation and soil function maps. We demonstrate the use of interpolated soil function maps as well as non-contiguous (but combined) vegetation and soil function maps and comment on their combined usability to assess related ecosystem services.

Diek, Sanne; de Jong, Rogier; Braun, Daniela; Böhler, Jonas; Schaepman, Michael

2014-05-01

232

Imaging of hepatocellular carcinoma patient-derived xenografts using (89)Zr-labeled anti-glypican-3 monoclonal antibody.  

PubMed

Imaging probes for early detection of hepatocellular carcinoma (HCC) are highly desired to overcome current diagnostic limitations which lead to poor prognosis. The membrane protein glypican-3 (GPC3) is a potential molecular target for early HCC detection as it is over-expressed in >50% of HCCs, and is associated with early hepatocarcinogenesis. We synthesized the positron emission tomography (PET) probe (89)Zr-DFO-1G12 by bioconjugating and radiolabeling the anti-GPC3 monoclonal antibody (clone 1G12) with (89)Zr, and evaluated its tumor-targeting capacity. In vitro, (89)Zr-DFO-1G12 was specifically taken up into GPC3-positive HCC cells only, but not in the GPC3-negative prostate cancer cell line (PC3). In vivo, (89)Zr-DFO-1G12 specifically accumulated in subcutaneous GPC3-positive HCC xenografts only, but not in PC3 xenografts. Importantly, (89)Zr-DFO-1G12 delineated orthotopic HCC xenografts from surrounding normal liver, with tumor/liver (T/L) ratios of 6.65 ± 1.33 for HepG2, and 4.29 ± 0.52 for Hep3B xenografts. It also delineated orthotopic xenografts derived from three GPC3-positive HCC patient specimens, with T/L ratios of 4.21 ± 0.64, 2.78 ± 0.26, and 2.31 ± 0.38 at 168 h p.i. Thus, (89)Zr-DFO-1G12 is a highly translatable probe for the specific and high contrast imaging of GPC3-positive HCCs, which may aid early detection of HCC to allow timely intervention. PMID:24836949

Yang, Xiaoyang; Liu, Hongguang; Sun, Chris K; Natarajan, Arutselvan; Hu, Xiang; Wang, Xiaolin; Allegretta, Mark; Guttmann, Ronald D; Gambhir, Sanjiv S; Chua, Mei-Sze; Cheng, Zhen; So, Samuel K

2014-08-01

233

Inputs for L2 Acquisition.  

ERIC Educational Resources Information Center

Major approaches of describing or examining linguistic data from a potential target language (input) are analyzed for adequacy in addressing the concerns of second language learning theory. Suggestions are made for making the best of these varied concepts of input and for reformulation of a unified concept. (MSE)

Saleemi, Anjum P.

1989-01-01

234

Online algorithms with stochastic input  

Microsoft Academic Search

The design and analysis of online algorithms, where the input to the algorithm is revealed over time and the algorithm has to make decisions immediately without knowing the future input, has received a revived interest in the last few years primarily due to their application to online advertising. The canonical problem is the Adwords problem, which is motivated by the

Nikhil R. Devanur

2011-01-01

235

Sensitivity analysis for RADTRAN 4 input parameters  

SciTech Connect

The transportation risk analysis code, RADTRAN 4, computer estimates of incident-free dose consequence and accident dose-risk. The output of the code includes a tabulation of sensitivity of the result to variation of the input parameters for the incident-free analysis. The values are calculated using closed mathematical expressions derived from the constitutive equations, which are linear. However, the equations for accident risk are not linear, in general, and a similar tabulation has not been available. Because of the importance of knowing how accident-risk estimates are affected by uncertainties in the input parameters, a direct investigation was undertaken of the variation in calculated accident dose-risk with changes in individual parameters. A limited, representative group of transportation scenarios was used, initially, to determine which of 23 accident-risk parameters affect the calculated accident dose risk significantly. Many of the parameters were observed to have minimal effect on the output, and others were judged as ``fixed`` either by regulation, convention or standards. The remaining 5 variables were selected for further study through Latin Hypercube Sampling (LHS). LHS yields statistical information from observations (risk calculations) resulting from multiple input-parameter sets compiled from ``random`` sampling of parameter distributions. The LHS method requires fewer observations than classical Monte Carlo methods to yield statistically significant results. This paper presents the preliminary parameter study and LHS application results together with further LHS evaluations of RADTRAN input parameters.

Mills, G.S.; Neuhauser, K.S.

1995-02-01

236

Field-aligned distribution of the plasmaspheric electron density: An empirical model derived from the IMAGE RPI measurements  

NASA Astrophysics Data System (ADS)

We present a newly developed empirical model of the plasma density in the plasmasphere. It is based on more than 700 density profiles along field lines derived from active sounding measurements made by the radio plasma imager on IMAGE between June 2000 and July 2005. The measurements cover all magnetic local times and vary from L = 1.6 to L = 4 spatially, with every case manually confirmed to be within the plasmasphere by studying the corresponding dynamic spectrogram. The resulting model depends not only on L-shell but also on magnetic latitude and can be applied to specify the electron densities in the plasmasphere between 2000 km altitude and the plasmapause (the plasmapause location itself is not included in this model). It consists of two parts: the equatorial density, which falls off exponentially as a function of L-shell; and the field-aligned dependence on magnetic latitude and L-shell (in the form of invariant magnetic latitude). The fluctuations of density appear to be greater than what could be explained by a possible dependence on magnetic local time or season, and the dependence on geomagnetic activity is weak and cannot be discerned. The solar cycle effect is not included because the database covers only a fraction of a solar cycle. The performance of the model is evaluated by comparison to four previously developed plasmaspheric models and is further tested against the in situ passive IMAGE RPI measurements of the upper hybrid resonance frequency. While the equatorial densities of different models are mostly within the statistical uncertainties (especially at distances greater than L = 3), the clear latitudinal dependence of the RPI model presents an improvement over previous models. The model shows that the field-aligned density distribution can be treated neither as constant nor as a simple diffusive equilibrium distribution profile. This electron density model combined with an assumed model of the ion composition can be used to estimate the time for an Alfven wave to propagate from one hemisphere to the other, to determine the plasma frequencies along a field line, and to calculate the raypaths for high frequency waves propagating in the plasmasphere.

Ozhogin, P.; Tu, J.; Song, P.; Reinisch, B. W.

2012-06-01

237

Using Concept Maps to Assess the Effect of Graphing Calculators Use on Students' Concept Images of the Derivative at a Point  

ERIC Educational Resources Information Center

This study used concept maps to investigate the effect of using graphing calculators on students' understanding of the derivative at a point. The study looked for differences between the concept images that are held by students' who are using graphing calculators and the students who are not using them. Seventy one students enrolled in two…

Serhan, Derar

2009-01-01

238

Identification of a novel indoline derivative for in vivo fluorescent imaging of blood-brain barrier disruption in animal models.  

PubMed

Disruption of the blood-brain barrier (BBB) can occur in various pathophysiological conditions. Administration of extraneous tracers that can pass the disrupted, but not the intact, BBB and detection of the extravasation have been widely used to assess BBB disruption in animal models. Although several fluorescent tracers have been successfully used, the administration of these tracers basically requires intravascular injection, which can be laborious when using small animals such as zebrafish. To identify fluorescent tracers that could be easily administered into various animal models and visualize the BBB disruption in vivo, we prepared nine structurally related indoline derivatives (IDs) as a minimum set of diverse fluorescent compounds. We found that one ID, ZMB741, had the highest affinity for serum albumin and emitted the strongest fluorescence in the presence of serum albumin of the nine IDs tested. The affinity to serum albumin and the fluorescence intensity was superior to those of Evans blue and indocyanine green that have been conventionally used to assess the BBB disruption. We showed that ZMB741 could be administered into zebrafish by static immersion or mice by intraperitoneal injection and visualizes the active disruption of their BBB. These results suggest that ZMB741 can be a convenient and versatile tool for in vivo fluorescent imaging of BBB disruption in various animal models. The strategy used in this study can also be applied to diversity-oriented libraries to identify novel fluorescent tracers that may be superior to ZMB741. PMID:23668665

Nishimura, Yuhei; Yata, Kenichiro; Nomoto, Tsuyoshi; Ogiwara, Tomoaki; Watanabe, Kohei; Shintou, Taichi; Tsuboyama, Akira; Okano, Mie; Umemoto, Noriko; Zhang, Zi; Kawabata, Miko; Zhang, Beibei; Kuroyanagi, Junya; Shimada, Yasuhito; Miyazaki, Takeshi; Imamura, Takeshi; Tomimoto, Hidekazu; Tanaka, Toshio

2013-08-21

239

Radioiodinated benzimidazole derivatives as single photon emission computed tomography probes for imaging of ?-amyloid plaques in Alzheimer's disease.  

PubMed

Five iodinated 2-phenyl-1H-benzo[d]imidazole derivatives were synthesized and evaluated as potential probes for ?-amyloid (A?) plaques. One of the compounds, 4-(6-iodo-1H-benzo[d]imidazol-2-yl)-N,N-dimethylaniline (12), showed excellent affinity for A?(1-42) aggregates (K(i) = 9.8 nM). Autoradiography with sections of postmortem Alzheimer's disease (AD) brain revealed that a radioiodinated probe [(125)I]12, labeled A? plaques selectively with low nonspecific binding. Biodistribution experiments with normal mice injected intravenously with [(125)I]12 showed high uptake [4.14 percent injected dose per gram (% ID/g) at 2 min] into and rapid clearance (0.15% ID/g at 60 min) from the brain, which may bring about a good signal-to-noise ratio and therefore achieve highly sensitive detection of A? plaques. In addition, [(125)I]12 labeled amyloid plaques in vivo in an AD transgenic model. The preliminary results strongly suggest that [(125)I]12 bears characteristics suitable for detecting amyloid plaques in vivo. When labeled with (123)I, it may be a useful SPECT imaging agent for A? plaques in the brain of living AD patients. PMID:21492779

Cui, Mengchao; Ono, Masahiro; Kimura, Hiroyuki; Kawashima, Hidekazu; Liu, Bo Li; Saji, Hideo

2011-04-01

240

Synthesis and evaluation of (18)F-labeled mitiglinide derivatives as positron emission tomography tracers for ?-cell imaging.  

PubMed

Measuring changes in ?-cell mass in vivo during progression of diabetes mellitus is important for understanding the pathogenesis, facilitating early diagnosis, and developing novel therapeutics for this disease. However, a non-invasive method has not been developed. A novel series of mitiglinide derivatives (o-FMIT, m-FMIT and p-FMIT; FMITs) were synthesized and their binding affinity for the sulfonylurea receptor 1 (SUR1) of pancreatic islets were evaluated by inhibition studies. (+)-(S)-o-FMIT had the highest affinity of our synthesized FMITs (IC50=1.8?M). (+)-(S)-o-[(18)F]FMIT was obtained with radiochemical yield of 18% by radiofluorination of racemic precursor 7, hydrolysis, and optical resolution with chiral HPLC; its radiochemical purity was >99%. In biodistribution experiments using normal mice, (+)-(S)-o-[(18)F]FMIT showed 1.94±0.42% ID/g of pancreatic uptake at 5min p.i., and decreases in radioactivity in the liver (located close to the pancreas) was relatively rapid. Ex vivo autoradiography experiments using pancreatic sections confirmed accumulation of (+)-(S)-o-[(18)F]FMIT in pancreatic ?-cells. These results suggest that (+)-(S)-o-[(18)F]FMIT meets the basic requirements for an radiotracer, and could be a candidate positron emission tomography tracer for in vivo imaging of pancreatic ?-cells. PMID:24842616

Kimura, Hiroyuki; Matsuda, Hirokazu; Fujimoto, Hiroyuki; Arimitsu, Kenji; Toyoda, Kentaro; Mukai, Eri; Nakamura, Hiroshi; Ogawa, Yu; Takagi, Mikako; Ono, Masahiro; Inagaki, Nobuya; Saji, Hideo

2014-07-01

241

Biological activity and magnetic resonance imaging of superparamagnetic iron oxide nanoparticles-labeled adipose-derived stem cells  

PubMed Central

Introduction No comparative study of adipose-derived stem cells (ADSCs) and bone marrow mesenchymal stem cells (BMSCs) by using superparamagnetic iron oxide nanoparticles (SPIOs)-labeling and magnetic resonance imaging (MRI) has been performed. Methods We studied the biological activity and MRI of ADSCs by labeling them with SPIOs and comparing them with BMSCs. After incubating the cells in culture medium with different levels of SPIOs (control group: 0 ?g/ml; Groups 1 to 3: 25, 50, and 100 ?g/ml) for 24 hours, we compared ADSCs with BMSCs in terms of intracellular iron content, labeling efficiency, and cell viability. Stem cells in the culture medium containing 50 ?g/ml SPIOs were induced into osteoblasts and fat cells. Adipogenic and osteogenic differentiation potentials were compared. R2* values of MRI in vitro were compared. Results The results showed that labeling efficiency was highest in Group 2. Intracellular iron content and R2* values increased with increasing concentrations of SPIOs, whereas cell viability decreased with increasing concentrations of SPIOs, and adipogenic and osteogenic differentiation potentials decreased. However, we found no significant difference between the two kinds of cells for any of these indexes. Conclusions ADSCs can be labeled and traced as easily as BMSCs in vitro. Given their abundance and higher proliferative capacity, as was previously shown, ADSCs may be better suited to stem cell therapy than are BMSCs.

2013-01-01

242

Temporal and Spatial Assessment of Yearly Solar Maps Derived from Satellite Images over the UAE and Qatar  

NASA Astrophysics Data System (ADS)

The unique climate of countries located within the Arabian Peninsula, characterized by high dust concentrations, high humidity and modest cloud coverage, requires regional models to retrieve the solar irradiance components from satellite images. An artificial neural network (ANN) model has shown promising results in estimating the direct normal, diffuse horizontal and global horizontal irradiances using thermal satellite channels over the United Arab Emirates (UAE). This model is trained with six thermal channels of the SEVIRI instrument, onboard Meteosat Second Generation, along with the solar zenith angle, day number, solar time and eccentricity correction. The outputs of this model are the solar irradiance components at 15-min temporal and 3-km spatial resolutions, which are then utilized to derive the daily, monthly and yearly irradiation maps over the UAE and Qatar. The purpose of this research is to examine the temporal and spatial variations for annual irradiation maps over the UAE and Qatar, derived using the ANN approach. For the period ranging from 2008 to 2010, the year of 2009 shows the lowest annual direct normal and global horizontal irradiation, and the highest diffuse horizontal irradiation. That is due to frequent dust events which occurred during 2009. The annual direct normal irradiation maps for 2008 to 2010 show the same trend, with the higher irradiation values in the southern area of UAE and the values decreasing as the coast approaches in the northern region. For any given year, Qatar generally shows lower direct normal irradiation values than the UAE. This might be explained by higher humidity in Qatar due to its coastal climate. As for the annual diffuse horizontal irradiation maps, the lower irradiation values are observed in the southern area of UAE and along some coastal regions, with the higher values being in the middle. Qatar shows higher values in the western region, due to the increased airborne dust coming from Saudi Arabia, as opposed to the eastern coast which is along the Arabian Gulf. The annual global horizontal irradiation maps show less spatial variations. For the UAE the values consistently increase from north to south, while for Qatar lower values are observed along the eastern coast and the higher values are in the inland and southern locations. The direct normal irradiation map over the UAE and Qatar for the year 2010, which had values greater than 2008 and 2009.

Eissa, Y.; Marpu, P. R.; Ghedira, H.; Chiesa, M.

2012-12-01

243

Synthetic Morphology Using Alternative Inputs  

PubMed Central

Designing the shape and size of a cell is an interesting challenge for synthetic biology. Prolonged exposure to the mating pheromone ?-factor induces an unusual morphology in yeast cells: multiple mating projections. The goal of this work was to reproduce the multiple projections phenotype in the absence of ?-factor using a gain-of-function approach termed “Alternative Inputs (AIs)”. An alternative input is defined as any genetic manipulation that can activate the signaling pathway instead of the natural input. Interestingly, none of the alternative inputs were sufficient to produce multiple projections although some produced a single projection. Then, we extended our search by creating all combinations of alternative inputs and deletions that were summarized in an AIs-Deletions matrix. We found a genetic manipulation (AI-Ste5p ste2?) that enhanced the formation of multiple projections. Following up this lead, we demonstrated that AI-Ste4p and AI-Ste5p were sufficient to produce multiple projections when combined. Further, we showed that overexpression of a membrane-targeted form of Ste5p alone could also induce multiple projections. Thus, we successfully re-engineered the multiple projections mating morphology using alternative inputs without ?-factor.

Tanaka, Hiromasa; Yi, Tau-Mu

2009-01-01

244

An exploration of thresholds in retinex theory towards digital image processing of remotely sensed imagery  

Microsoft Academic Search

Optical remote sensing employs radiometric corrections to obtain measures of surface reflectance. Depending upon the particular application, these procedures may require intensive image processing and the specification of many external input parameters. This study uses principles derived from human colour vision research to help design new radiometric correction procedures that are simple, image-based, and perform reliably for a variety of

Katja Christine Bach

2000-01-01

245

Multiple input/output random vibration control system  

NASA Technical Reports Server (NTRS)

A multi-input/output random vibration control algorithm was developed based on system identification concepts derived from random vibration spectral analysis theory. The unique features of the algorithm are: (1) the number of input excitors and the number of output control responses need not be identical; (2) the system inverse response matrix is obtained directly from the input/output spectral matrix; and (3) the system inverse response matrix is updated every control loop cycle to accommodate system amplitude nonlinearities. A laboratory demonstration case of two imputs with three outputs is presented to demonstrate the system capabilities.

Unruh, James F.

1988-01-01

246

Inverting Amplifier with Current Input  

NSDL National Science Digital Library

This animated gif illustrates the changing voltages a conventional inverting amplifier when it receives input from a current source rather than a voltage source. Notice that the input resistor does not offer any impedance. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations.Other 3-D Circuit Animations can be seen here.

2009-11-23

247

Erythrocyte-derived photo-theranostic agents: hybrid nano-vesicles containing indocyanine green for near infrared imaging and therapeutic applications  

NASA Astrophysics Data System (ADS)

Development of theranostic nano-constructs may enable diagnosis and treatment of diseases at high spatial resolution. Some key requirements for clinical translation of such constructs are that they must be non-toxic, non-immunogenic, biodegradable, with extended circulating lifetime. Cell-based structures, particularly those derived from erythrocytes, are promising candidate carrier systems to satisfy these requirements. One particular type of theranostic materials utilize light-sensitive agents that once photo-activated can provide diagnostic imaging capability, and elicit therapeutic effects. Here we demonstrate the first successful engineering of hybrid nano-scale constructs derived from membranes of hemoglobin-depleted erythrocytes that encapsulate the near infrared chromophore, indocyanine green. We show the utility of the constructs as photo-theranostic agents in fluorescence imaging and photothermal destruction of human cells. These erythrocyte-mimicking nano-structures can be derived autologously, and may have broad applications in personal nanomedicine ranging from imaging and photo-destruction of cancerous tissues to vascular abnormalities, and longitudinal evaluations of therapeutic interventions.

Bahmani, Baharak; Bacon, Danielle; Anvari, Bahman

2013-07-01

248

Erythrocyte-derived photo-theranostic agents: hybrid nano-vesicles containing indocyanine green for near infrared imaging and therapeutic applications  

PubMed Central

Development of theranostic nano-constructs may enable diagnosis and treatment of diseases at high spatial resolution. Some key requirements for clinical translation of such constructs are that they must be non-toxic, non-immunogenic, biodegradable, with extended circulating lifetime. Cell-based structures, particularly those derived from erythrocytes, are promising candidate carrier systems to satisfy these requirements. One particular type of theranostic materials utilize light-sensitive agents that once photo-activated can provide diagnostic imaging capability, and elicit therapeutic effects. Here we demonstrate the first successful engineering of hybrid nano-scale constructs derived from membranes of hemoglobin-depleted erythrocytes that encapsulate the near infrared chromophore, indocyanine green. We show the utility of the constructs as photo-theranostic agents in fluorescence imaging and photothermal destruction of human cells. These erythrocyte-mimicking nano-structures can be derived autologously, and may have broad applications in personal nanomedicine ranging from imaging and photo-destruction of cancerous tissues to vascular abnormalities, and longitudinal evaluations of therapeutic interventions.

Bahmani, Baharak; Bacon, Danielle; Anvari, Bahman

2013-01-01

249

The value of satellite-derived snow cover images for calibrating a hydrological model in snow-dominated catchments in Central Asia  

NASA Astrophysics Data System (ADS)

satellite-derived snow cover data for hydrologic model calibration can be a good way to improve model internal consistency. This study applied a multiobjective genetic algorithm to characterize the trade-off curve between model performance in terms of discharge and snow cover area (SCA). Using a Monte Carlo-based approach, we further investigated the additional information content of an increasing number of SCA scenes used in the calibration period. The study was performed in six snowmelt-dominated headwater catchments of the Karadarya Basin in Kyrgyzstan, Central Asia, using the hydrological model WASA and snow cover data from four melt seasons retrieved from AVHRR (Advanced Very High Resolution Radiometer). We generally found only small trade-offs between good simulations with respect to discharge and SCA, but good model performance with respect to discharge did not exclude low performance in terms of SCA. On average, the snow cover error in the validation period could be reduced by very few images in the calibration period. Increasing the number of images resulted in only small further improvements. However, using only a small number of images involves the risk that these particular images cause the selection of parameter sets which are not representative for the catchment. It is therefore advisable to use a larger number of images. In this study, it was necessary to include at least 10-16 images.

Duethmann, Doris; Peters, Juliane; Blume, Theresa; Vorogushyn, Sergiy; Güntner, Andreas

2014-03-01

250

Estimation of the input parameters in the Feller neuronal model.  

PubMed

The stochastic Feller neuronal model is studied, and estimators of the model input parameters, depending on the firing regime of the process, are derived. Closed expressions for the first two moments of functionals of the first-passage time (FTP) through a constant boundary in the suprathreshold regime are derived, which are used to calculate moment estimators. In the subthreshold regime, the exponentiality of the FTP is utilized to characterize the input parameters. The methods are illustrated on simulated data. Finally, approximations of the first-passage-time moments are suggested, and biological interpretations and comparisons of the parameters in the Feller and the Ornstein-Uhlenbeck models are discussed. PMID:16906867

Ditlevsen, Susanne; Lansky, Petr

2006-06-01

251

Towards radiological diagnosis of abdominal adhesions based on motion signatures derived from sequences of cine-MRI images.  

PubMed

This paper reports novel development and preliminary application of an image registration technique for diagnosis of abdominal adhesions imaged with cine-MRI (cMRI). Adhesions can severely compromise the movement and physiological function of the abdominal contents, and their presence is difficult to detect. The image registration approach presented here is designed to expose anomalies in movement of the abdominal organs, providing a movement signature that is indicative of underlying structural abnormalities. Validation of the technique was performed using structurally based in vitro and in silico models, supported with Receiver Operating Characteristic (ROC) methods. For the more challenging cases presented to the small cohort of 4 observers, the AUC (area under curve) improved from a mean value of 0.67 ± 0.02 (without image registration assistance) to a value of 0.87 ± 0.02 when image registration support was included. Also, in these cases, a reduction in time to diagnosis was observed, decreasing by between 20% and 50%. These results provided sufficient confidence to apply the image registration diagnostic protocol to sample magnetic resonance imaging data from healthy volunteers as well as a patient suffering from encapsulating peritoneal sclerosis (an extreme form of adhesions) where immobilization of the gut by cocooning of the small bowel is observed. The results as a whole support the hypothesis that movement analysis using image registration offers a possible method for detecting underlying structural anomalies and encourages further investigation. PMID:24439767

Fenner, John; Wright, Benjamin; Emberey, Jonathan; Spencer, Paul; Gillott, Richard; Summers, Angela; Hutchinson, Charles; Lawford, Pat; Brenchley, Paul; Bardhan, Karna Dev

2014-06-01

252

INPUT-DRIVEN LANGUAGE LEARNING  

Microsoft Academic Search

Input-driven models provide an explicit and readily testable account of language learning. Although we share Ellis's view that the statisti- cal structure of the linguistic environment is a crucial and, until re- cently, relatively neglected variable in language learning, we also recognize that the approach makes three assumptions about cogni- tion and language learning that are not universally shared. The

Michael Harrington; Simon Dennis

2002-01-01

253

On 3D Input Devices  

Microsoft Academic Search

We provide an overview of some of our input device developments, which we designed in response to the need for more advanced 3D interfaces. Some of our devices are more task-specific and others are more general, but all of them support six or more degrees of freedom (DOF) and work in three dimensions. In our work, we try to understand

Bernd Fröhlich; Jan Hochstrate; Alexander Kulik; Anke Huckauf

2006-01-01

254

Dynamic input consensus using integrators  

Microsoft Academic Search

The consensus or agreement problem enables a team of agents to agree on certain information variables using a low-bandwidth, dynamic, and sparsely-connected graph. How- ever, most prior work on agreement protocols has focused on converging to a single, static variable. In this paper, we propose a consensus filter that accepts dynamically changing inputs at each agent. We analyze several properties

Clark N. Taylor; Randal W. Beard; Jeffrey Humpherys

2011-01-01

255

Lab Inputs for Common Micros.  

ERIC Educational Resources Information Center

The game paddle inputs of Apple microcomputers provide a simple way to get laboratory measurements into the computer. Discusses these game paddles and the necessary interface software. Includes schematics for Apple built-in paddle electronics, TRS-80 game paddle I/O, Commodore circuit for user port, and bus interface for Sinclair/Timex, Commodore,…

Tinker, Robert

1984-01-01

256

Input selection for ANFIS learning  

Microsoft Academic Search

We present a quick and straightfoward way of input selection for neuro-fuzzy modeling using adaptive neuro-fuzzy inference systems (ANFIS). The method is tested on two real-world problems: the nonlinear regression problem of automobile MPG (miles per gallon) prediction, and the nonlinear system identification using the Box and Jenkins gas furnace data

Jyh-shing Roger Jang

1996-01-01

257

Modeling Input Validation in UML  

Microsoft Academic Search

Security is an integral part of most software systems but it is not considered as an explicit part in the development process yet. Input validation is the most critical part of software security that is not covered in the design phase of software development life-cycle resulting in many security vulnerabilities. Our objective is to extend UML to new integrated framework

Pedram Hayati; Nastaran Jafari; S. Mohammad Rezaei; Saeed Sarenche; Vidyasagar Potdar

2008-01-01

258

Analog Input Data Acquisition Software  

NASA Technical Reports Server (NTRS)

DAQ Master Software allows users to easily set up a system to monitor up to five analog input channels and save the data after acquisition. This program was written in LabVIEW 8.0, and requires the LabVIEW runtime engine 8.0 to run the executable.

Arens, Ellen

2009-01-01

259

Image processing apparatus and image processing method  

US Patent & Trademark Office Database

An exposure condition when obtaining a sensed image is input. Shake information when obtaining the sensed image is input. A filter to be used to correct a blur of the sensed image is generated based on the exposure condition and a weight value including a non-integer obtained from the shake information.

2013-12-10

260

EXE: automatically generating inputs of death  

Microsoft Academic Search

This paper presents EXE, an effective bug-finding tool that automatically generates inputs that crash real code. Instead of running code on manually or randomly constructed input, EXE runs it on symbolic input initially allowed to be \\

Cristian Cadar; Vijay Ganesh; Peter M. Pawlowski; David L. Dill; Dawson R. Engler

2006-01-01

261

Systems and methods for reconfiguring input devices  

NASA Technical Reports Server (NTRS)

A system includes an input device having first and second input members configured to be activated by a user. The input device is configured to generate activation signals associated with activation of the first and second input members, and each of the first and second input members are associated with an input function. A processor is coupled to the input device and configured to receive the activation signals. A memory coupled to the processor, and includes a reconfiguration module configured to store the input functions assigned to the first and second input members and, upon execution of the processor, to reconfigure the input functions assigned to the input members when the first input member is inoperable.

Lancaster, Jeff (Inventor); De Mers, Robert E. (Inventor)

2012-01-01

262

Aerosol and Cloud Properties at the Huygens Entry Site as Derived from the Descent Imager/Spectral  

NASA Technical Reports Server (NTRS)

The Huygens Probe descended through Titan s atmosphere on January 14, 2005. The Descent Imager/Spectral Radiometer (DISR) instrument made optical measurements which constrain the nature and vertical distribution and of the aerosols in the atmosphere.

Doose, L. R.; Engel, S.; Tomasko, M. G.; Dafoe, L. E.; West, R.; Lemmon, M.

2005-01-01

263

Combined Optical Imaging and Mammography of the Healthy Breast: Optical Contrast Derived From Breast Structure and Compression  

Microsoft Academic Search

In this paper, we report new progress in developing the instrument and software platform of a combined X-ray mammography\\/diffuse optical breast imaging system. Particu- larly, we focus on system validation using a series of balloon phantom experiments and the optical image analysis of 49 healthy patients. Using the finite-element method for forward modeling and a regularized Gauss-Newton method for parameter

Qianqian Fang; Stefan A. Carp; Juliette Selb; Gregory Boverman; Quan Zhang; Daniel B. Kopans; Richard H. Moore; Eric L. Miller; Dana H. Brooks; David A. Boas

2009-01-01

264

Development of a Fluorescence-Based Imaging System for Colon Cancer Diagnosis Using Two Novel Rhodamine Derivatives  

Microsoft Academic Search

. Tissue characterisation by endoscopic fluorescence imaging of exogenous fluorophores appears to be a promising method for\\u000a cancer detection. Cationic and lipophilic fluorescence compounds of the aminoxanthene chemical family, have been found to\\u000a exhibit selective accumulation in various carcinoma cells.\\u000a \\u000a In this paper the development of an endoscopic fluorescence-based imaging system with the additional capability of collecting\\u000a emission spectra is

D. Yova; V. Atlamazoglou; N. Kavantzas; S. Loukas

2000-01-01

265

Validation of GOES-9 Satellite-Derived Cloud Properties over the Tropical Western Pacific Region  

NASA Technical Reports Server (NTRS)

Real-time processing of hourly GOES-9 images in the ARM TWP region began operationally in October 2003 and is continuing. The ARM sites provide an excellent source for validating this new satellitederived cloud and radiation property dataset. Derived cloud amounts, heights, and broadband shortwave fluxes are compared with similar quantities derived from ground-based instrumentation. The results will provide guidance for estimating uncertainties in the GOES-9 products and to develop improvements in the retrieval methodologies and input.

Khaiyer, Mandana M.; Nordeen, Michele L.; Doeling, David R.; Chakrapani, Venkatasan; Minnis, Patrick; Smith, William L., Jr.

2004-01-01

266

Structural response and input identification  

NASA Technical Reports Server (NTRS)

Three major goals were delineated: (1) to develop a general method for determining the response of a structure to combined base and acoustic random excitation: (2) to develop parametric relationships to aid in the design of plates which are subjected to random force or random base excitation: (3) to develop a method to identify the individual acoustic and base input to a structure with only a limited number of measurement channels, when both types of excitation act simultaneously.

Shepard, G. D.; Callahan, J. C.; Mcelman, J. A.

1981-01-01

267

An in vivo validation study of ultrasonic strain imaging: a comparison of strain derived by ultrasonic strain rate imaging, gray-scale M-mode and MRI  

Microsoft Academic Search

Strain rate imaging (SRI) is a new method to quantify regional myocardial deformation. It has been validated against other technique. However, these studies have been limited to validating peak strain values. As the temporal evolution of the strain curve is believed to contain important information on the functional consequences of regional pathology, we compared the complete strain curve as measured

L. Herbots; J. D'hooge; F. Maes; S. Dymarkowski; P. Mertens; P. Claus; B. Bijnens; J. Bogaert; F. E. Rademakers; G. R. Sutherland

2003-01-01

268

Medical image integrity control and forensics based on watermarking--approximating local modifications and identifying global image alterations.  

PubMed

In this paper we present a medical image integrity verification system that not only allows detecting and approximating malevolent local image alterations (e.g. removal or addition of findings) but is also capable to identify the nature of global image processing applied to the image (e.g. lossy compression, filtering …). For that purpose, we propose an image signature derived from the geometric moments of pixel blocks. Such a signature is computed over regions of interest of the image and then watermarked in regions of non interest. Image integrity analysis is conducted by comparing embedded and recomputed signatures. If any, local modifications are approximated through the determination of the parameters of the nearest generalized 2D Gaussian. Image moments are taken as image features and serve as inputs to one classifier we learned to discriminate the type of global image processing. Experimental results with both local and global modifications illustrate the overall performances of our approach. PMID:22256212

Huang, H; Coatrieux, G; Shu, H Z; Luo, L M; Roux, Ch

2011-01-01

269

Reduction of shading-derived artifacts in skin chromophore imaging without measurements or assumptions about the shape of the subject  

NASA Astrophysics Data System (ADS)

To quantitatively evaluate skin chromophores over a wide region of curved skin surface, we propose an approach that suppresses the effect of the shading-derived error in the reflectance on the estimation of chromophore concentrations, without sacrificing the accuracy of that estimation. In our method, we use multiple regression analysis, assuming the absorbance spectrum as the response variable and the extinction coefficients of melanin, oxygenated hemoglobin, and deoxygenated hemoglobin as the predictor variables. The concentrations of melanin and total hemoglobin are determined from the multiple regression coefficients using compensation formulae (CF) based on the diffuse reflectance spectra derived from a Monte Carlo simulation. To suppress the shading-derived error, we investigated three different combinations of multiple regression coefficients for the CF. In vivo measurements with the forearm skin demonstrated that the proposed approach can reduce the estimation errors that are due to shading-derived errors in the reflectance. With the best combination of multiple regression coefficients, we estimated that the ratio of the error to the chromophore concentrations is about 10%. The proposed method does not require any measurements or assumptions about the shape of the subjects; this is an advantage over other studies related to the reduction of shading-derived errors.

Yoshida, Kenichiro; Nishidate, Izumi; Ojima, Nobutoshi; Iwata, Kayoko

2014-01-01

270

Input impedance of probe-excited rectangular microstrip patch radiator  

Microsoft Academic Search

An expression for the input impedance seen by the coaxial line feeding a rectangular patch radiator is derived, taking the effect of wall admittance, conductor and dielectric losses into account. The real part of wall admittance of the patch radiator is determined from the angular spectrum of plane waves in the visible region of the wave-number plane, and its imaginary

Asok De; B. N. Das

1984-01-01

271

Human Factors Inputs to the Training Device Design Process.  

ERIC Educational Resources Information Center

Guidelines are presented for achieving human factors inputs to the design of synthetic training systems. A method is developed for design and organization of training concepts and data supportive to the human factors specialist in deriving the functional specifications for the design of any complex training device. Three major sections are…

Smode, Alfred F.

272

PET kinetic modeling without the need of input curve  

Microsoft Academic Search

In PET imaging, application of kinetic modeling always requires an input curve (IC) together with the PET data. The IC can be obtained by means of external blood sampling or, in the case of cardiac studies, by means of region-of-interest (ROI) drawn on the blood pool. It is, however, very unsuitable to withdraw and to analyse blood samples, and in

M. Bentourkia

2003-01-01

273

Visual Input Driving Human Smooth-Pursuit Eye Movements.  

National Technical Information Service (NTIS)

Current computational models of smooth-pursuit eye movements assume that the primary visual input is local retinal-image motion (often referred to as retinal slip). However, we show that humans can pursue object motion with considerable accuracy, even in ...

L. S. Stone, B. R. Beutter, J. Lorenceau

1996-01-01

274

Combined Optical Imaging and Mammography of the Healthy Breast: Optical Contrast Derived From Breast Structure and Compression  

PubMed Central

In this paper, we report new progress in developing the instrument and software platform of a combined X-ray mammography/diffuse optical breast imaging system. Particularly, we focus on system validation using a series of balloon phantom experiments and the optical image analysis of 49 healthy patients. Using the finite-element method for forward modeling and a regularized Gauss-Newton method for parameter reconstruction, we recovered the inclusions inside the phantom and the hemoglobin images of the human breasts. An enhanced coupling coefficient estimation scheme was also incorporated to improve the accuracy and robustness of the reconstructions. The recovered average total hemoglobin concentration (HbT) and oxygen saturation (SO2) from 68 breast measurements are 16.2 ?m and 71%, respectively, where the HbT presents a linear trend with breast density. The low HbT value compared to literature is likely due to the associated mammographic compression. From the spatially co-registered optical/X-ray images, we can identify the chest-wall muscle, fatty tissue, and fibroglandular regions with an average HbT of 20.1±6.1 ?m for fibroglandular tissue, 15.4±5.0 ?m for adipose, and 22.2±7.3 ?m for muscle tissue. The differences between fibroglandular tissue and the corresponding adipose tissue are significant (p < 0.0001). At the same time, we recognize that the optical images are influenced, to a certain extent, by mammographical compression. The optical images from a subset of patients show composite features from both tissue structure and pressure distribution. We present mechanical simulations which further confirm this hypothesis.

Fang, Qianqian; Carp, Stefan A.; Selb, Juliette; Boverman, Greg; Zhang, Quan; Kopans, Daniel B.; Moore, Richard H.; Miller, Eric L.; Brooks, Dana H.; Boas, David A.

2009-01-01

275

Self-disabling chip enable input  

US Patent & Trademark Office Database

A multi-die memory package may have separate chip enable inputs for the respective memory dice. Individual chip enable inputs may be separated by other chip connections such as power and ground. The memory dice may include multiple chip enable inputs to allow easy wire bonding of the individual chip enable inputs to a die without requiring any jumpers within the package. Circuitry may be included so that undriven chip enable inputs are masked and driven chip enable inputs may be propagated to the memory die to enable memory accesses while a single chip enable input is only connected to the capacitance of a single bonding pad.

2014-01-14

276

Validation of a novel CHX-A'' derivative suitable for peptide conjugation: small animal PET/CT imaging using yttrium-86-CHX-A''-octreotide.  

PubMed

A versatile bifunctional chelating reagent based on a preorganized cyclohexyl derivative of DTPA (CHX-A'') has been developed for the convenient N-terminal labeling of peptides with metal ion radionuclides of Bi(III), In(III), Lu(III), or Y(III). This was achieved via the synthesis of a mono-N-hydroxysuccinimidyl penta-tert-butyl ester derivative of CHX-A'' (trans-cyclohexyldiethylenetriaminepenta-acetic acid) featuring a glutaric acid spacer. Commercially obtained octreotide was modified at its N-terminus by this reagent in the solution phase, and its subsequent radiolabeling with (111)In (T(1/2) = 2.8 d) and (86)Y (T(1/2) = 14.7 h) demonstrated. Small animal PET/CT imaging results of (86)Y-CHX-A''-octreotide in a somatostatin receptor-positive tumor-bearing rat model are presented for the validation of the novel agent. PMID:16821789

Clifford, Thomas; Boswell, C Andrew; Biddlecombe, Grainne B; Lewis, Jason S; Brechbiel, Martin W

2006-07-13

277

Comparative analysis of folate derived PET imaging agents with [(18)F]-2-fluoro-2-deoxy-d-glucose using a rodent inflammatory paw model.  

PubMed

Activated macrophages play a significant role in initiation and progression of inflammatory diseases and may serve as the basis for the development of targeted diagnostic methods for imaging sites of inflammation. Folate receptor beta (FR-?) is differentially expressed on activated macrophages associated with inflammatory disease states yet is absent in either quiescent or resting macrophages. Because folate binds with high affinity to FR-?, development of folate directed imaging agents has proceeded rapidly in the past decade. However, reports of PET based imaging agents for use in inflammatory conditions remain limited. To investigate whether FR-? expressing macrophages could be exploited for PET based inflammatory imaging, two separate folate-targeted PET imaging agents were developed, 4-[(18)F]-fluorophenylfolate and [(68)Ga]-DOTA-folate, and their ability to target activated macrophages were examined in a rodent inflammatory paw model. We further compared inflamed tissue uptake with 2-[(18)F]fluoro-2-deoxy-d-glucose ([(18)F]-FDG). microPET analysis demonstrated that both folate-targeted PET tracers had higher uptake in the inflamed paw compared to the control paw. When these radiotracers were compared to [(18)F]-FDG, both folate PET tracers had a higher signal-to-noise ratio (SNR) than [(18)F]-FDG, suggesting that folate tracers may be superior to [(18)F]-FDG in detecting diseases with an inflammatory component. Moreover, both folate-PET imaging agents also bind to FR-? which is overexpressed on multiple human cancers. Therefore, these folate derived PET tracers may also find use for localizing and staging FR(+) cancers, monitoring response to therapy, and for selecting patients for tandem folate-targeted therapies. PMID:23819524

Kularatne, Sumith A; Bélanger, Marie-José; Meng, Xiangjun; Connolly, Brett M; Vanko, Amy; Suresch, Donna L; Guenther, Ilonka; Wang, Shubing; Low, Philip S; McQuade, Paul; Trotter, Dinko González

2013-08-01

278

Naval threat countermeasure simulator and the IR_CRUISE_missiles models for the generation of infrared (IR) videos of maritime targets and background for input into advanced imaging IR seekers  

NASA Astrophysics Data System (ADS)

A new hardware-in-the-loop modeling technique was developed at the US Naval Research Laboratory (NRL) for the evaluation of IR countermeasures against advanced IR imaging anti-ship cruise missiles. The research efforts involved the creation of tools to generate accurate IR imagery and synthesize video to inject in to real-world threat simulators. A validation study was conducted to verify the accuracy and limitations of the techniques that were developed.

Taczak, Thomas M.; Dries, John W.; Gover, Robert E.; Snapp, Mary Ann; Williams, Elmer F.; Cahill, Colin P.

2002-07-01

279

Investigation of iodine-123-labelled amino acid derivatives for imaging cerebral gliomas: uptake in human glioma cells and evaluation in stereotactically implanted C6 glioma rats  

Microsoft Academic Search

In developing iodine-123-labelled amino acid derivatives for imaging cerebral gliomas by single-photon emission tomography (SPET), we compared p-[123I]iodo-l-phenylalanine (IPA), l-[123I]iodo-1,2,3,4-tetrahydro-7-hydroxyisoquinoline-3-carboxylic acid (ITIC) and l-3-[123I]iodo-!-methyltyrosine (IMT) with regard to their uptake in human glioblastoma T99 and T3868 cells, and thereafter studied the mechanisms promoting the cellular uptake. The potential of the 123I-iodinated agents for use as SPET radiopharmaceuticals was evaluated in

Samuel Samnick; Sven Richter; Bernd F. Romeike; Axel Heimann; Wolfgang Feiden; Oliver Kempski; Carl-Martin Kirsch

2000-01-01

280

Elimination of direct derivative along source trajectory for accurate image reconstruction in helical cone-beam CT  

Microsoft Academic Search

An important breakthrough in helical cone-beam reconstruction is the development of Katsevich's algorithms, which appear to have numerous advantages over the algorithms developed previously. The original algorithm proposed by Katsevich has a simple form and requires only once the computation of the data filtering. It, however, invokes a derivative of the data function with respect to the rotation angle along

Yu Zou; Xiaochuan Pan

2004-01-01

281

High-resolution thermal inertia derived from the Thermal Emission Imaging System (THEMIS): Thermal model and applications  

Microsoft Academic Search

Thermal inertia values at 100 m per pixel are determined using nighttime temperature data from the Thermal Emission Imaging System (THEMIS) on the Mars Odyssey spacecraft, producing the highest-resolution thermal inertia data set to date. THEMIS thermal inertia values have an overall accuracy of ?20%, a precision of 10–15%, and are consistent with both Thermal Emission Spectrometer orbital and Miniature

Robin L. Fergason; Philip R. Christensen; Hugh H. Kieffer

2006-01-01

282

Tropical forest phenology and metabolism: Integrated analysis of tower-mounted camera images and tower derived GPP for interpreting ecosystem scale processes  

NASA Astrophysics Data System (ADS)

Seasonal and interannual patterns of leaf development and metabolism are a central topic of global change ecology. However, the seasonality of leaf development in tropical forests remains poorly understood due to the relatively low variation in climate, the high biodiversity of tropical biomes and the limitations of current observation techniques. In this study, we aim to demonstrate the feasibility of using near-surface remote sensing techniques to understand the phenology of an evergreen tropical forest (Tapajos National Forest or TNF site, Santarem, Para, Brazil), and how this phenology affects the metabolism of tropical vegetation. Two continuous years (2010-2011) of daily images from a tower mounted three-channel (red, green, and near-infrared) TetraCAM ADC camera were analyzed for this study. A new approach was developed based on an automatic image classification scheme which decomposed the images into two components (leaves and bare wood) to extract seasonality of leaf development. A confusion matrix method was used to assess the accuracy of image classification. MODIS EVI composites (MOD13Q1) were also acquired and processed for the TNF site (5km*5km). The camera based phenology information was first compared with MODIS EVI, and then combined with tower based eddy covariance measurements at the same site to quantify the effect of canopy-scale phenology on ecosystem metabolism. We found that: (1) Tower-based images revealed a clear seasonal pattern in leaf phenology that was supported by confusion matrix analysis. Matrix analysis gave a 96.7% user accuracy (user accuracy represents the probability that an image pixel classification actually corresponds to that category on the ground) for the leaf component, based on 24 images in 2010 (2 images per month). The tower-based pattern matched that retrieved from satellites (camera-sensed leaf phenology vs monthly MODIS EVI (01/2010-12/2011, R2=0.57, P-value<0.01). This suggests that quality-controlled MODIS EVI accurately captures optical phenology patterns observed near the ground in tropical regions, strong evidence against the previously suggested idea that tropical MODIS data are contaminated by atmospheric artifacts. (2) In particular, seasonal patterns observed from satellite and tower were robust to changes in solar zenith angle (SZA), which had a small effect in camera and satellite-derived leaf phenology, but this effect was secondary to the overall seasonal pattern of leaf development detected. (3) We also found the image classification scheme to be able to monitor the phenology of individual tree species. These results suggest this method to be a feasible way to monitor the complex phenology of a tropical forest system. (4)Net leaf production was extracted by applying a first derivative of monthly camera detected leaf component percentage (termed 'leaf phenology' in this study). Monthly net leaf production (02/2010-12/2011) was correlated with monthly eddy covariance derived light use efficiency (R2=0.59, P-value<0.01), but with ~4 months time lag. This might be associated with leaf age dependent physiological status (recently matured leaves have higher photosynthetic capacity compared with both newly emerged and previous growing leaves), a hypothesis that we are currently investigating.

Wu, J.; Restrepo-Coupe, N.; Hayek, M.; Stark, S. C.; Smith, M.; Wiedemann, K.; Marostica, S.; Ferreira, M.; Woodcock, T.; Prohaska, N.; da Silva, R.; Nelson, B. W.; Huete, A. R.; Saleska, S. R.

2013-12-01

283

Development of a 111In-labeled peptide derivative targeting a chemokine receptor, CXCR4, for imaging tumors  

Microsoft Academic Search

The chemokine receptor CXCR4 is highly expressed in tumor cells and plays an important role in tumor metastasis. The aim of this study was to develop a radiopharmaceutical for the imaging of CXCR4-expressing tumors in vivo. Based on structure–activity relationships, we designed a 14-residue peptidic CXCR4 inhibitor, Ac-TZ14011, as a precursor for radiolabeled peptides. For 111In-labeling, diethylenetriaminepentaacetic acid (DTPA) was

Hirofumi Hanaoka; Takahiro Mukai; Hirokazu Tamamura; Tomohiko Mori; Seigo Ishino; Kazuma Ogawa; Yasuhiko Iida; Ryuichiro Doi; Nobutaka Fujii; Hideo Saji

2006-01-01

284

Elimination of direct derivative along source trajectory for accurate image reconstruction in helical cone-beam CT  

NASA Astrophysics Data System (ADS)

An important breakthrough in helical cone-beam reconstruction is the development of Katsevich's algorithms, which appear to have numerous advantages over the algorithms developed previously. The original algorithm proposed by Katsevich has a simple form and requires only once the computation of the data filtering. It, however, invokes a derivative of the data function with respect to the rotation angle along the helical trajectory and thus makes the algorithm numerically susceptible to the sample aliasing along the helical trajectory. A modified version of the algorithm later developed by Katsevich that avoids the explicit computation of the derivative of the data function along the helical trajectory. However, this modified algorithm contains more terms than does the original algorithm and involves two different filtering of the data function. Therefore, this modified algorithm is computationally more complex and demanding than does the original Katsevich's algorithm. In this work, based upon the original Katsevich's algorithm, we present a new algorithm that not only avoids explicit computation of the derivative of the data function along the helical trajectory but also requires only one filtering of the data function. Therefore, in general, our algorithm is quantitatively more accurate than the original Katsevich's algorithm and is computationally more efficient than the modified Katsevich's algorithm.

Zou, Yu; Pan, Xiaochuan

2004-05-01

285

MR elastography derived shear stiffness-a new imaging biomarker for the assessment of early tumor response to chemotherapy.  

PubMed

Purpose: The overall goal is to develop magnetic resonance elastography derived shear stiffness as a biomarker for the early identification of chemotherapy response, allowing dose, agent type and treatment regimen to be tailored on a per patient basis, improving therapeutic outcome and minimizing normal tissue toxicity. The specific purpose of this study is to test the feasibility of this novel biomarker to measure the treatment response in a well-known chemotherapy model. Methods: Tumors were grown in the right flank of genetically modified mice by subcutaneous injection of DoHH2 (non-Hodgkin's lymphoma) cells. Magnetic resonance elastography was used to quantify tumor stiffness before and after injection of a chemotherapeutic agent or saline. Histological tests were also performed on the tumors. Results: A significant decrease (P < 0.0001) in magnetic resonance elastography-derived tumor shear stiffness was observed within 4 days of chemotherapy treatment, while no appreciable change was observed in saline-treated tumors. No significant change in volume occurred at this early stage, but there were decreased levels of cellular proliferation in chemotherapy-treated tumors. Conclusion: These results demonstrate that magnetic resonance elastography-derived estimates of shear stiffness reflect an initial response to cytotoxic therapy and suggest that this metric could be an early and sensitive biomarker of tumor response to chemotherapy. Magn Reson Med 71:1834-1840, 2014. © 2013 Wiley Periodicals, Inc. PMID:23801372

Pepin, Kay M; Chen, Jun; Glaser, Kevin J; Mariappan, Yogesh K; Reuland, Brian; Ziesmer, Steven; Carter, Rickey; Ansell, Stephen M; Ehman, Richard L; McGee, Kiaran P

2014-05-01

286

In vivo bioluminescence imaging validation of a human biopsy-derived orthotopic mouse model of glioblastoma multiforme.  

PubMed

Glioblastoma multiforme (GBM), the most aggressive brain malignancy, is characterized by extensive cellular proliferation, angiogenesis, and single-cell infiltration into the brain. We have previously shown that a xenograft model based on serial xenotransplantation of human biopsy spheroids in immunodeficient rodents maintains the genotype and phenotype of the original patient tumor. The present work further extends this model for optical assessment of tumor engraftment and growth using bioluminescence imaging (BLI). A method for successful lentiviral transduction of the firefly luciferase gene into multicellular spheroids was developed and implemented to generate optically active patient tumor cells. Luciferase-expressing spheroids were injected into the brains of immunodeficient mice. BLI photon counts and tumor volumes from magnetic resonance imaging (MRI) were correlated. Luciferase-expressing tumors recapitulated the histopathologic hallmarks of human GBMs and showed proliferation rates and microvessel density counts similar to those of wild-type xenografts. Moreover, we detected widespread invasion of luciferase-positive tumor cells in the mouse brains. Herein we describe a novel optically active model of GBM that closely mimics human pathology with respect to invasion, angiogenesis, and proliferation indices. The model may thus be routinely used for the assessment of novel anti-GBM therapeutic approaches implementing well-established and cost-effective optical imaging strategies. PMID:23490442

Jarzabek, Monika A; Huszthy, Peter C; Skaftnesmo, Kai O; McCormack, Emmet; Dicker, Patrick; Prehn, Jochen H M; Bjerkvig, Rolf; Byrne, Annette T

2013-05-01

287

Differentiation of Glioblastoma Multiforme and Single Brain Metastasis by Peak Height and Percentage of Signal Intensity Recovery Derived from Dynamic Susceptibility-Weighted Contrast-Enhanced Perfusion MR Imaging  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Glioblastoma multiforme (GBM) and single brain metastasis (MET) are the 2 most common malignant brain tumors that can appear similar on anatomic imaging but require vastly different treatment strategy. The purpose of our study was to determine whether the peak height and the percentage of signal intensity recovery derived from dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion MR imaging

S. Cha; J. M. Lupo; M.-H. Chen; K. R. Lamborn; M. W. McDermott; M. S. Berger; S. J. Nelson; W. P. Dillon

2007-01-01

288

Optimal gadolinium dose level for magnetic resonance imaging (MRI) contrast enhancement of U87-derived tumors in athymic nude rats for the assessment of photodynamic therapy  

NASA Astrophysics Data System (ADS)

This study aims to determine the effect of varying gadopentetate dimeglumine (Gd-DTPA) dose on Dynamic Contrast Enhanced-Magnetic Resonance Imaging (DCE-MRI) tracking of brain tumor photodynamic therapy (PDT) outcome. Methods: We injected 2.5 x 105 U87 cells (derived from human malignant glioma) into the brains of six athymic nude rats. After 9, 12, and 13 days DCE-MRI images were acquired on a 9.4 T micro-MRI scanner before and after administration of 100, 150, or 200 ?L of Gd-DTPA. Results: Tumor region normalized DCE-MRI scan enhancement at peak was: 1.217 over baseline (0.018 Standard Error [SE]) at the 100 ?L dose, 1.339 (0.013 SE) at the 150 ?L dose, and 1.287 (0.014 SE) at the 200 ?L dose. DCE-MRI peak tumor enhancement at the 150 ?L dose was significantly greater than both the 100 ?L dose (p < 3.323E-08) and 200 ?L dose (p < 0.0007396). Discussion: In this preliminary study, the 150 ?L Gd-DTPA dose provided the greatest T1 weighted contrast enhancement, while minimizing negative T2* effects, in DCE-MRI scans of U87-derived tumors. Maximizing Gd-DTPA enhancement in DCE-MRI scans may assist development of a clinically robust (i.e., unambiguous) technique for PDT outcome assessment.

Cross, Nathan; Varghai, Davood; Flask, Chris A.; Feyes, Denise K.; Oleinick, Nancy L.; Dean, David

2009-02-01

289

Self-consistent input-output formulation of quantum feedback  

SciTech Connect

A simple method of analyzing quantum feedback circuits is presented. The classical analysis of feedback circuits can be generalized to apply to quantum systems by mapping the field operators of various outputs to other inputs via the standard input-output formalism. Unfortunately, this has led to unphysical results such as the violation of the Heisenberg uncertainty principle for in-loop fields. This paper shows that this general approach can be redeemed by ensuring a self-consistently Hermitian Hamiltonian. The calculations are based on a noncommutative calculus of operator derivatives. A full description of several examples of quantum linear and nonlinear feedback for optical systems is presented.

Yanagisawa, M. [Department of Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Hope, J. J. [Department of Quantum Science, The Australian National University, Canberra, ACT 0200 (Australia)

2010-12-15

290

Multiple input electrode gap controller  

DOEpatents

A method and apparatus for controlling vacuum arc remelting (VAR) furnaces by estimation of electrode gap based on a plurality of secondary estimates derived from furnace outputs. The estimation is preferably performed by Kalman filter. Adaptive gain techniques may be employed, as well as detection of process anomalies such as glows.

Hysinger, Christopher L. (Austin, TX); Beaman, Joseph J. (Austin, TX); Melgaard, David K. (Albuquerque, NE); Williamson, Rodney L. (Albuquerque, NE)

1999-01-01

291

Multiple input electrode gap controller  

DOEpatents

A method and apparatus for controlling vacuum arc remelting (VAR) furnaces by estimation of electrode gap based on a plurality of secondary estimates derived from furnace outputs. The estimation is preferably performed by Kalman filter. Adaptive gain techniques may be employed, as well as detection of process anomalies such as glows. 17 figs.

Hysinger, C.L.; Beaman, J.J.; Melgaard, D.K.; Williamson, R.L.

1999-07-27

292

Radioiodinated benzimidazole derivatives as single photon emission computed tomography probes for imaging of ?-amyloid plaques in Alzheimer's disease  

Microsoft Academic Search

Five iodinated 2-phenyl-1H-benzo[d]imidazole derivatives were synthesized and evaluated as potential probes for ?-amyloid (A?) plaques. One of the compounds, 4-(6-iodo-1H-benzo[d]imidazol-2-yl)-N,N-dimethylaniline (12), showed excellent affinity for A?1-42 aggregates (Ki=9.8 nM). Autoradiography with sections of postmortem Alzheimer's disease (AD) brain revealed that a radioiodinated probe [125I]12, labeled A? plaques selectively with low nonspecific binding. Biodistribution experiments with normal mice injected intravenously with

Mengchao Cui; Masahiro Ono; Hiroyuki Kimura; Hidekazu Kawashima; Bo Li Liu; Hideo Saji

2011-01-01

293

Images.  

ERIC Educational Resources Information Center

The theme of this month's issue is "Images"--from early paintings and statuary to computer-generated design. Resources on the theme include Web sites, CD-ROMs and software, videos, books, and others. A page of reproducible activities is also provided. Features include photojournalism, inspirational Web sites, art history, pop art, and myths. (AEF)

Barr, Catherine, Ed.

1997-01-01

294

Global diffusion tensor imaging derived metrics differentiate glioblastoma multiforme vs. normal brains by using discriminant analysis: introduction of a novel whole-brain approach  

PubMed Central

Background Histological behavior of glioblastoma multiforme suggests it would benefit more from a global rather than regional evaluation. A global (whole-brain) calculation of diffusion tensor imaging (DTI) derived tensor metrics offers a valid method to detect the integrity of white matter structures without missing infiltrated brain areas not seen in conventional sequences. In this study we calculated a predictive model of brain infiltration in patients with glioblastoma using global tensor metrics. Methods Retrospective, case and control study; 11 global DTI-derived tensor metrics were calculated in 27 patients with glioblastoma multiforme and 34 controls: mean diffusivity, fractional anisotropy, pure isotropic diffusion, pure anisotropic diffusion, the total magnitude of the diffusion tensor, linear tensor, planar tensor, spherical tensor, relative anisotropy, axial diffusivity and radial diffusivity. The multivariate discriminant analysis of these variables (including age) with a diagnostic test evaluation was performed. Results The simultaneous analysis of 732 measures from 12 continuous variables in 61 subjects revealed one discriminant model that significantly differentiated normal brains and brains with glioblastoma: Wilks’ ? = 0.324, ?2 (3) = 38.907, p < .001. The overall predictive accuracy was 92.7%. Conclusions We present a phase II study introducing a novel global approach using DTI-derived biomarkers of brain impairment. The final predictive model selected only three metrics: axial diffusivity, spherical tensor and linear tensor. These metrics might be clinically applied for diagnosis, follow-up, and the study of other neurological diseases.

Roldan-Valadez, Ernesto; Rios, Camilo; Cortez-Conradis, David; Favila, Rafael; Moreno-Jimenez, Sergio

2014-01-01

295

Morphology and development of left-handed singlets derived from mirror-image doublets of Stylonychia mytilus.  

PubMed

Mirror-image doublets of Stylonychia mytilus include 2 sets of cortical structures, one with the normal "right-handed" (RH) arrangement, the other with a reversed "left-handed" (LH) arrangement. These sets, however, are incomplete, with certain structures, most notably cirri of the right marginal type, missing near the line of symmetry. When a mirror-image doublet is bisected longitudinally to separate the RH and LH components physically, each fragment undergoes a regeneration process that restores a complete set of cortical structures, including the previously missing cirri of the right marginal type. In the resulting LH cell, all ciliary structures are present in an arrangement that is globally reversed in relation to that found in RH cells; in particular, marginal cirri of the left-marginal type are formed at the cell's right margin, and marginal cirri of the right-marginal type are produced at the cell's left margin. Whereas the regenerated RH fragment always divides and initiates a clone of normal singlets, the LH fragment, though structurally nearly complete, in all cases eventually dies without dividing. The cause of death is starvation due to the formation of an abnormal oral apparatus. In the Discussion, we consider the nature and consequences of a reversal of global positional information. PMID:2106028

Shi, X B; Qiu, Z J; Frankel, J

1990-01-01

296

The Pulsation of ? Cygni Imaged by Optical Interferometry: A Novel Technique to Derive Distance and Mass of Mira Stars  

NASA Astrophysics Data System (ADS)

We present infrared interferometric imaging of the S-type Mira star ? Cygni. The object was observed at four different epochs in 2005-2006 with the Infrared-Optical Telescope Array optical interferometer (H band). Images show up to 40% variation in the stellar diameter, as well as significant changes in the limb darkening and stellar inhomogeneities. Model fitting gave precise time-dependent values of the stellar diameter, and reveals presence and displacement of a warm molecular layer. The star radius, corrected for limb darkening, has a mean value of 12.1 mas and shows a 5.1 mas amplitude pulsation. Minimum diameter was observed at phase 0.94 ± 0.01. Maximum temperature was observed several days later at phase 1.02 ± 0.02. We also show that combining the angular acceleration of the molecular layer with CO (?v = 3) radial velocity measurements yields a 5.9 ± 1.5 mas parallax. The constant acceleration of the CO molecules—during 80% of the pulsation cycle—lead us to argument for a free-falling layer. The acceleration is compatible with a gravitational field produced by a 2.1+1.5 -0.7 solar mass star. This last value is in agreement with fundamental mode pulsator models. We foresee increased development of techniques consisting in combining radial velocity with interferometric angular measurements, ultimately allowing total mapping of the speed, density, and position of the diverse species in pulsation-driven atmospheres.

Lacour, S.; Thiébaut, E.; Perrin, G.; Meimon, S.; Haubois, X.; Pedretti, E.; Ridgway, S. T.; Monnier, J. D.; Berger, J. P.; Schuller, P. A.; Woodruff, H.; Poncelet, A.; Le Coroller, H.; Millan-Gabet, R.; Lacasse, M.; Traub, W.

2009-12-01

297

Live-cell imaging of phosphatidic acid dynamics in pollen tubes visualized by Spo20p-derived biosensor.  

PubMed

Although phosphatidic acid (PA) is structurally the simplest membrane phospholipid, it has been implicated in the regulation of many cellular events, including cytoskeletal dynamics, membrane trafficking and stress responses. Plant PA shows rapid turnover but the information about its spatio-temporal distribution in plant cells is missing. Here we demonstrate the use of a lipid biosensor that enables us to monitor PA dynamics in plant cells. The biosensor consists of a PA-binding domain of yeast SNARE Spo20p fused to fluorescent proteins. Live-cell imaging of PA dynamics in transiently transformed tobacco (Nicotiana tabacum) pollen tubes was performed using confocal laser scanning microscopy. In growing pollen tubes, PA shows distinct annulus-like fluorescence pattern in the plasma membrane behind the extreme tip. Coexpression studies with markers for other plasmalemma signaling lipids phosphatidylinositol 4,5-bisphosphate and diacylglycerol revealed limited colocalization at the shoulders of the apex. PA distribution and concentrations show distinct responses to various lipid signaling inhibitors. Fluorescence recovery after photobleaching (FRAP) analysis suggests high PA turnover in the plasma membrane. Our data show that a biosensor based on the Spo20p-PA binding domain is suitable for live-cell imaging of PA also in plant cells. In tobacco pollen tubes, distinct subapical PA maximum corroborates its involvement in the regulation of endocytosis and actin dynamics. PMID:24750036

Potocký, Martin; Pleskot, Roman; Pejchar, P?emysl; Vitale, Nicolas; Kost, Benedikt; Zárský, Viktor

2014-07-01

298

Digital image processing of vascular angiograms  

NASA Technical Reports Server (NTRS)

A computer image processing technique was developed to estimate the degree of atherosclerosis in the human femoral artery. With an angiographic film of the vessel as input, the computer was programmed to estimate vessel abnormality through a series of measurements, some derived primarily from the vessel edge information and others from optical density variations within the lumen shadow. These measurements were combined into an atherosclerosis index, which was found to correlate well with both visual and chemical estimates of atherosclerotic disease.

Selzer, R. H.; Blankenhorn, D. H.; Beckenbach, E. S.; Crawford, D. W.; Brooks, S. H.

1975-01-01

299

Image quality assessment based on distortion identification  

NASA Astrophysics Data System (ADS)

A New Global Full-Reference Image Quality System based on classification and fusion scheme is proposed. It consists of many steps. The first step is devoted to the identification of the type of degradation contained in a given image based a Linear Discriminant Analysis (LDA) classifier using some common Image Quality Metric (IQM) as feature inputs. An IQM per degradation (IQM-D) is then used to estimate the quality of the image. For a given degradation type, the appropriate IQM-D is derived by combining the top three best IQMs using an Artificial Neural Network model. The performance of the proposed scheme is evaluated first in terms of good degradation identification. Then, for each distortion type the image quality estimation is evaluated in terms of good correlation with the subjective judgments using the TID 2008 image database.

Chetouani, Aladine; Beghdadi, Azeddine

2011-01-01

300

Input Variable Selection for Hydrologic Modeling Using Anns  

NASA Astrophysics Data System (ADS)

The use of artificial neural network (ANN) models in water resources applications has grown considerably over the last couple of decades. In learning problems, where a connectionist network is trained with a finite sized training set, better generalization performance is often obtained when unneeded weights in the network are eliminated. One source of unneeded weights comes from the inclusion of input variables that provide little information about the output variables. Hence, in the ANN modeling methodology, one of the approaches that has received little attention, is the selection of appropriate model inputs. In the past, different methods have been used for identifying and eliminating these input variables. Normally, linear methods of Auto Correlation Function (ACF) and Partial Auto Correlation Function (PACF) have been adopted. For nonlinear physical systems e.g. hydrological systems, model inputs selected based on the linear correlation analysis among input and output variables cannot assure to capture the non-linearity in the system. In the present study, two of the non-linear methods have been explored for the Input Variable Selection (IVS). The linear method employing ACF and PACF is also used for comparison purposes. The first non-linear method utilizes a measure of the Mutual Information Criterion (MIC) to characterize the dependence between a potential model input and the output, which is a step wise input selection procedure. The second non-linear method is improvement over the first method which eliminates redundant inputs based on a partial measure of mutual information criterion (PMIC), which is also a step wise procedure. Further, the number of input variables to be considered for the development of ANN model was determined using the Principal Component Analysis (PCA), which previously used to be done by trial and error approach. The daily river flow data derived from Godavari River Basin @ Polavaram, Andhra Pradesh, India, and the daily average rainfall data of three rain gauge stations spatially distributed in Godavari River Basin have been employed to evaluate all the IVS methods for ANN hydrologic model development. Single hidden layer architecture trained using Levenberg-Marquardt algorithm (LMA) has been employed. A wide range of error statistics was used to evaluate the performance of all the models developed with different input selection methods in this study. It has been found that PCA helps to fix the number of input variables to be considered for the model development. The results obtained show that the ANN hydrologic model developed using the inputs based on the first non-linear method performed better than the model developed using the inputs based on the linear method. Further, the ANN hydrologic model developed using the inputs based on the second non-linear method performed the best among all the models developed on various IVS methods investigated in this study. It is recommended that PCA should first be used to determine the number of inputs to be selected and then the second non-linear method should be used to select the specific inputs for the development of ANN hydrologic model.

Ganti, R.; Jain, A.

2011-12-01

301

Flight Test Validation of Optimal Input Design and Comparison to Conventional Inputs  

NASA Technical Reports Server (NTRS)

A technique for designing optimal inputs for aerodynamic parameter estimation was flight tested on the F-18 High Angle of Attack Research Vehicle (HARV). Model parameter accuracies calculated from flight test data were compared on an equal basis for optimal input designs and conventional inputs at the same flight condition. In spite of errors in the a priori input design models and distortions of the input form by the feedback control system, the optimal inputs increased estimated parameter accuracies compared to conventional 3-2-1-1 and doublet inputs. In addition, the tests using optimal input designs demonstrated enhanced design flexibility, allowing the optimal input design technique to use a larger input amplitude to achieve further increases in estimated parameter accuracy without departing from the desired flight test condition. This work validated the analysis used to develop the optimal input designs, and demonstrated the feasibility and practical utility of the optimal input design technique.

Morelli, Eugene A.

1997-01-01

302

Apparatus and method for inputting alphabet characters  

US Patent & Trademark Office Database

The invention shows the effective input of a target word or phrase by applying a Full Input Method and by using an index storing full code. In addition, this invention proposes an input system for inputting various objects (alphabet characters, special characters, functions, etc) by combination of a long stroke of a button and a short stroke of the button, and by combination of a long stroke of a button and a short stroke of a control button.

2009-12-01

303

Some aspects of lunar and martian volcanism as examined with spectral, topographic, and morphologic data derived from spacecraft images  

NASA Astrophysics Data System (ADS)

Utilizing newly calibrated Mariner 10 color images, the titanium abundances of lunar mare soils on the eastern limb and farside are examined. These maria are found to have TiO2 contents in the range of less than 2 to 5%. The existence of cryptomare deposits northeast of Mare Marginis is confirmed. This leads to the prediction that no high TiO2 (greater than 8 wt%) mare basalt soils will be found in regions with thickened crust (most of the lunar farside) that are yet to be examine with spectrometers, due to the greater density of high titanium magma. Utilizing Viking Orbiter and Mariner 9 data, the martian volcanoes Biblis Patera, Ceraunius Tholus, Jovis Tholus, Ulysses Patera Uranius Patera, and Uranius Tholus are analyzed. Specifically, morphologic and topographic features indicative of the eruption style (effusive vs. explosive) that formed each edifice are examined. From new digital mosaics of these volcanoes, both effusive and explosive deposits are found. It is proposed that the initial period of activity for some martian volcanoes was dominantly explosive (driven by juvenile gases), whereas later activity was mostly effusive. In support a this hypothesis, an analysis of the martian volcano Apollinaris Patera is presented. Using digital images, thermal inertia data and a new topographic model, the chronology of Apollinaris Patera is determined to have been dominated early on by explosive activity, followed by later effusive eruption. From the topographic data, its volume is estimated to be approximately 105/cu km. The volcano may have been active for approximately 107 yrs, based on its volume and an inferred rate of eruption of 1.5 x 10-2/cu km/yr. It is proposed that at least 2 x 1016 kg of juvenile water was added to the martian atmosphere as a consequence of these eruptions. Detailed examination of a multi-temporal series of Viking Orbiter color images of the Apollinaris Patera region shows, that, for a given area on the surface, the red over violet ratio varies from 2.9 to 3.4, and the albedo ranges from 21 to 16%. These changes are interpreted to be predominately due to variations in the amount of atmospheric condensates.

Robinson, Mark Southwick

304

Input filter compensation for switching regulators  

NASA Technical Reports Server (NTRS)

Problems caused by input filter interaction and conventional input filter design techniques are discussed. The concept of feedforward control is modeled with an input filter and a buck regulator. Experimental measurement and comparison to the analytical predictions is carried out. Transient response and the use of a feedforward loop to stabilize the regulator system is described. Other possible applications for feedforward control are included.

Lee, F. C.

1984-01-01

305

Input Devices for Young Handicapped Children.  

ERIC Educational Resources Information Center

The versatility of the computer can be expanded considerably for young handicapped children by using input devices other than the typewriter-style keyboard. Input devices appropriate for young children can be classified into four categories: alternative keyboards, contact switches, speech input devices, and cursor control devices. Described are…

Morris, Karen

306

Effects of Auditory Input in Individuation Tasks  

ERIC Educational Resources Information Center

Under many conditions auditory input interferes with visual processing, especially early in development. These interference effects are often more pronounced when the auditory input is unfamiliar than when the auditory input is familiar (e.g. human speech, pre-familiarized sounds, etc.). The current study extends this research by examining how…

Robinson, Christopher W.; Sloutsky, Vladimir M.

2008-01-01

307

Textual Enhancement of Input: Issues and Possibilities  

ERIC Educational Resources Information Center

The input enhancement hypothesis proposed by Sharwood Smith (1991, 1993) has stimulated considerable research over the last 15 years. This article reviews the research on textual enhancement of input (TE), an area where the majority of input enhancement studies have aggregated. Methodological idiosyncrasies are the norm of this body of research.…

Han, ZhaoHong; Park, Eun Sung; Combs, Charles

2008-01-01

308

Input-Output Analyses of Schools.  

ERIC Educational Resources Information Center

Cognitive and noncognitive outputs are surveyed, as well as the effects of inputs on outputs. Groups of student inputs include background characteristics, school-related characteristics, and attitudes. School inputs include conditions and instructional personnel. The literature is surveyed by population samples, data aggregation, and statistical…

Glasman, Naftaly S.; Biniaminov, Israel

1981-01-01

309

Integrality and Separability of Input Devices  

Microsoft Academic Search

Current input device taxonomies and other frameworks typically emphasize the mechanical structure of input devices. We suggest that selecting an appropriate input device for an interactive task requires looking beyond the physical structure of devices to the deeper perceptual structure of the task, the device, and the interrelationship between the perceptual structure of the task and the control properties of

Robert J. K. Jacob; Linda E. Sibert; Daniel C. Mcfarlane; M. Preston Mullen Jr.

1994-01-01

310

A coumarin-derived fluorescent chemosensor for selectively detecting Cu(2+): Synthesis, DFT calculations and cell imaging applications.  

PubMed

A novel coumarin-based fluorescent probe L ((4E)-4-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl) methyleneamino)-1,2-dihyydro-2,3-dimethyl-1-phenylpyrazol-5-one) has been developed as a simple and efficient chemosensor which exhibits a significant fluorescence reduction in the presence of metal cations. This sensor exhibits high selectivity and sensitivity toward Cu(2+) over other common cations. The mechanism for detecting copper was evaluated by time-dependent density functional theory (TD-DFT) calculations and the coordination mode was also confirmed by density functional theory (DFT) calculations. Furthermore, results of cell imaging in this study indicate that this new probe may be useful for detection and monitoring of Cu(2+) in biological applications. PMID:24767455

Chen, Fengjuan; Liu, Guozhen; Shi, Yanjun; Xi, Pinxian; Cheng, Ju; Hong, Jinpeng; Shen, Rong; Yao, Xiaojun; Bai, Decheng; Zeng, Zhengzhi

2014-06-15

311

Direct reconstruction of PET receptor binding parametric images using a simplified reference tissue model  

NASA Astrophysics Data System (ADS)

Molecular imaging using dynamic positron emission tomography (PET) can provide in vivo images of physiologically or biochemically important parameters. Direct reconstruction of parametric images from dynamic PET sinograms is statistically more efficient than the conventional indirect methods, which perform image reconstruction and kinetic modeling in two separate steps. Most existing direct reconstruction methods are derived based on a known blood input function. This paper presents a direct reconstruction algorithm using a simplified reference tissue model, which does not require a blood input function. We have derived a minorization-maximization algorithm to find the penalized maximum likelihood solution. Computer simulations show that the proposed method has better bias-variance tradeoff than the conventional indirect method for estimating parametric images of receptor binding potential using dynamic PET.

Wang, Guobao; Qi, Jinyi

2009-02-01

312

Fusion of 3D models derived from TLS and image-based techniques for CH enhanced documentation  

NASA Astrophysics Data System (ADS)

Recognizing the various advantages offered by 3D new metric survey technologies in the Cultural Heritage documentation phase, this paper presents some tests of 3D model generation, using different methods, and their possible fusion. With the aim to define potentialities and problems deriving from integration or fusion of metric data acquired with different survey techniques, the elected test case is an outstanding Cultural Heritage item, presenting both widespread and specific complexities connected to the conservation of historical buildings. The site is the Staffarda Abbey, the most relevant evidence of medieval architecture in Piedmont. This application faced one of the most topical architectural issues consisting in the opportunity to study and analyze an object as a whole, from twice location of acquisition sensors, both the terrestrial and the aerial one. In particular, the work consists in the evaluation of chances deriving from a simple union or from the fusion of different 3D cloudmodels of the abbey, achieved by multi-sensor techniques. The aerial survey is based on a photogrammetric RPAS (Remotely piloted aircraft system) flight while the terrestrial acquisition have been fulfilled by laser scanning survey. Both techniques allowed to extract and process different point clouds and to generate consequent 3D continuous models which are characterized by different scale, that is to say different resolutions and diverse contents of details and precisions. Starting from these models, the proposed process, applied to a sample area of the building, aimed to test the generation of a unique 3Dmodel thorough a fusion of different sensor point clouds. Surely, the describing potential and the metric and thematic gains feasible by the final model exceeded those offered by the two detached models.

Bastonero, P.; Donadio, E.; Chiabrando, F.; Spanò, A.

2014-05-01

313

THE PULSATION OF chi CYGNI IMAGED BY OPTICAL INTERFEROMETRY: A NOVEL TECHNIQUE TO DERIVE DISTANCE AND MASS OF MIRA STARS  

SciTech Connect

We present infrared interferometric imaging of the S-type Mira star chi Cygni. The object was observed at four different epochs in 2005-2006 with the Infrared-Optical Telescope Array optical interferometer (H band). Images show up to 40% variation in the stellar diameter, as well as significant changes in the limb darkening and stellar inhomogeneities. Model fitting gave precise time-dependent values of the stellar diameter, and reveals presence and displacement of a warm molecular layer. The star radius, corrected for limb darkening, has a mean value of 12.1 mas and shows a 5.1 mas amplitude pulsation. Minimum diameter was observed at phase 0.94 +- 0.01. Maximum temperature was observed several days later at phase 1.02 +- 0.02. We also show that combining the angular acceleration of the molecular layer with CO (DELTAv = 3) radial velocity measurements yields a 5.9 +- 1.5 mas parallax. The constant acceleration of the CO molecules-during 80% of the pulsation cycle-lead us to argument for a free-falling layer. The acceleration is compatible with a gravitational field produced by a 2.1{sup +1.5} {sub -0.7} solar mass star. This last value is in agreement with fundamental mode pulsator models. We foresee increased development of techniques consisting in combining radial velocity with interferometric angular measurements, ultimately allowing total mapping of the speed, density, and position of the diverse species in pulsation-driven atmospheres.

Lacour, S.; Perrin, G.; Haubois, X.; Poncelet, A. [Observatoire de Paris, LESIA, CNRS/UMR 8109, 92190 Meudon (France); Thiebaut, E. [Centre de Recherche Astrophysique de Lyon, CNRS/UMR 5574, 69561 Saint Genis Laval (France); Meimon, S. [Office National d'Etudes et de Recherches Aeronautiques, DOTA, 92322 Chatillon (France); Pedretti, E. [School of Physics and Astronomy, University of St. Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom); Ridgway, S. T. [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726-6732 (United States); Monnier, J. D. [University of Michigan, Astronomy Department, 914 Dennison Bldg., 500 Church Street, Ann Arbor, MI 40109 (United States); Berger, J. P. [LAOG-UMR 5571, CNRS and Universite Joseph Fourier, BP 53, 38041 Grenoble (France); Schuller, P. A. [Institut d'Astrophysique Spatiale, CNRS/UMR 8617, Universite Paris-Sud, 91405 Orsay (France); Woodruff, H. [Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia); Le Coroller, H. [Observatoire de Haute-Provence, OHP/CNRS, F-04870 St. Michel l'Observatoire (France); Millan-Gabet, R. [Michelson Science Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125 (United States); Lacasse, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Traub, W. [Jet Propulsion Laboratory, California Institute of Technology, M/S 301-451, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

2009-12-10

314

The derivation and verification of surface reflectances using airborne MSS data and a radiative transfer model  

SciTech Connect

Surface reflectance images were derived from airborne MSS data using a radiative transfer model to eliminate atmospheric effects and to derive downwelling irradiances. Input radiative transfer model parameters and Brightness Value (BV) to radiance conversion gain and bias factors were generated for each band using an optimization procedure to minimize the difference between modelled and image BV. Subsequently, reflectance images were derived at five wavelengths from the blue to red bands using the optimized parameters as inputs into the radiative transfer model. Modelled surface reflectance images were evaluated for accuracy by statistical comparison to measured reflectances, and for improved contrast by subjective comparison to the original images. Daedalus DS-1260 MSS bands 3, 4 and 5 modelled reflectances explained 25%, 75% and 72% of the measured reflectance variances, respectively; while bands 2 and 7 correlation were not significant (p < .05). Finally, the generated reflectance images showed dramatic improvement in contrast, revealing textures that were not apparent in the original images. 20 refs., 4 figs., 3 tabs.

Ramsey, E.W. III; Jensen, J.R.

1988-01-01

315

Kinetic quantitation of cerebral PET-FDG studies without concurrent blood sampling: statistical recovery of the arterial input function.  

PubMed

Kinetic quantitation of dynamic positron emission tomography (PET) studies via compartmental modeling usually requires the time-course of the radio-tracer concentration in the arterial blood as an arterial input function (AIF). For human and animal imaging applications, significant practical difficulties are associated with direct arterial sampling and as a result there is substantial interest in alternative methods that require no blood sampling at the time of the study. A fixed population template input function derived from prior experience with directly sampled arterial curves is one possibility. Image-based extraction, including requisite adjustment for spillover and recovery, is another approach. The present work considers a hybrid statistical approach based on a penalty formulation in which the information derived from a priori studies is combined in a Bayesian manner with information contained in the sampled image data in order to obtain an input function estimate. The absolute scaling of the input is achieved by an empirical calibration equation involving the injected dose together with the subject's weight, height and gender. The technique is illustrated in the context of (18)F -Fluorodeoxyglucose (FDG) PET studies in humans. A collection of 79 arterially sampled FDG blood curves are used as a basis for a priori characterization of input function variability, including scaling characteristics. Data from a series of 12 dynamic cerebral FDG PET studies in normal subjects are used to evaluate the performance of the penalty-based AIF estimation technique. The focus of evaluations is on quantitation of FDG kinetics over a set of 10 regional brain structures. As well as the new method, a fixed population template AIF and a direct AIF estimate based on segmentation are also considered. Kinetics analyses resulting from these three AIFs are compared with those resulting from radially sampled AIFs. The proposed penalty-based AIF extraction method is found to achieve significant improvements over the fixed template and the segmentation methods. As well as achieving acceptable kinetic parameter accuracy, the quality of fit of the region of interest (ROI) time-course data based on the extracted AIF, matches results based on arterially sampled AIFs. In comparison, significant deviation in the estimation of FDG flux and degradation in ROI data fit are found with the template and segmentation methods. The proposed AIF extraction method is recommended for practical use. PMID:19709971

O'Sullivan, F; Kirrane, J; Muzi, M; O'Sullivan, J N; Spence, A M; Mankoff, D A; Krohn, K A

2010-03-01

316

Selective detection of volatile organic compounds by spectral imaging of porphyrin derivatives bound to TiO2 porous films.  

PubMed

In this work, the carboxylic acid derivatives of a free-base porphyrin, 5,10,15,20-tetrakis(4-carboxyphenyl)-21H,23H-porphyrin, and 10 of its metal derivatives (TCPPs) have been used for optical gas sensing. For this purpose, microstructured columnar TiO(2) thin films prepared by GAPVD (glancing angle physical vapor deposition) have been used as host materials for the porphyrins as they are non-dispersive and porous, allowing their use for UV-visible spectroscopy and gas sensing. The chemical binding between the dye molecules and the TiO(2) has been studied through infrared spectroscopy, and the obtained spectral changes have been found to be compatible with chelating and/or bidentate binding modes of the carboxylate groups on the TiO(2) surface. When hosted in the film, the UV-visible spectra of the porphyrins featured a blue shift and broadening of the Soret band with respect to the solution, which has been attributed to the formation of ?-? aggregates between porphyrin molecules. The composite porphyrin/TiO(2) films obtained from each of the 11 porphyrins have been exposed to 12 different volatile organic compounds (VOCs), and their respective gas-sensitive properties have been analyzed as a function of the spectral changes in their Soret band region in the presence of the analytes. The set of composite films has shown high selectivity to the analyzed volatile compounds. For each analyte, an innovative way of showing the different responses has been developed. By means of this procedure, an imagelike recognition pattern has been obtained, which allows an easy identification of every compound. The kinetics of the exposure to several analytes showed a fast, reversible and reproducible response, with response times of a few seconds, which has been attributed to both the sensitivity of the porphyrins and the high porosity of the TiO(2) films. Also, increasing concentrations of the analytes resulted in an increase in the magnitude of the response, indicating that the sensor behavior is also concentration-dependent. PMID:22985094

Roales, Javier; Pedrosa, José M; Castillero, Pedro; Cano, Manuel; Richardson, Tim H; Barranco, Ángel; González-Elipe, Agustín R

2012-10-24

317

Guided image filtering.  

PubMed

In this paper, we propose a novel explicit image filter called guided filter. Derived from a local linear model, the guided filter computes the filtering output by considering the content of a guidance image, which can be the input image itself or another different image. The guided filter can be used as an edge-preserving smoothing operator like the popular bilateral filter [1], but it has better behaviors near edges. The guided filter is also a more generic concept beyond smoothing: It can transfer the structures of the guidance image to the filtering output, enabling new filtering applications like dehazing and guided feathering. Moreover, the guided filter naturally has a fast and nonapproximate linear time algorithm, regardless of the kernel size and the intensity range. Currently, it is one of the fastest edge-preserving filters. Experiments show that the guided filter is both effective and efficient in a great variety of computer vision and computer graphics applications, including edge-aware smoothing, detail enhancement, HDR compression, image matting/feathering, dehazing, joint upsampling, etc. PMID:23599054

He, Kaiming; Sun, Jian; Tang, Xiaoou

2013-06-01

318

Morphology of an ICME-event derived by Multi-point in Situ and Heliospheric Imaging Data  

NASA Astrophysics Data System (ADS)

We show the analysis of an outstanding fast interplanetary coronal mass ejection (ICME) of 07 March 2012, which has been observed stereoscopically from both STEREO spacecraft. Assuming self-similar expansion and constant direction of motion we derive the kinematical profiles for the eastern and the western part of the roughly Earth-directed ICME. As additional constraints we use the huge advantage of in situ measurements at various locations during the ICME's propagation, namely from Venus Express, Messenger, Wind and Mars Express. We found that the eastern part of the ICME had a much higher propagation speed than its western part. Using the drag-based model, a model for the propagation of ICMEs in the inner heliosphere, we analyzed the influence of the drag on both sides of the ICME due to the surrounding solar wind conditions. These different solar wind conditions could have been the reason for the differing velocities and therefore for a distortion of the ICME front. These studies are fundamental in order to deepen the understanding of ICME evolution and to enhance existing forecasting methods.

Rollett, Tanja; Möstl, Christian; Temmer, Manuela; Veronig, Astrid M.; Frahm, Rudy A.; Davies, Jackie A.; Vrsnak, Bojan; Farrugia, Charles J.; Amerstorfer, Ute V.

2014-05-01

319

Use of paramagnetic chelated metal derivatives of polysaccharides and spin-labeled polysaccharides as contrast agents in magnetic resonance imaging  

SciTech Connect

Soluble and insoluble polysaccharides were derivatized with diethylenetriaminepentaacetic acid (DTPA) and/or spin-labeled with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). Polysaccharides derivatized with DTPA were prepared via cyanogen bromide activation, coupling to a diamine linker, and to DTPA anhydride. Spin-labeled polysaccharides were also prepared via cyanogen bromide activation. The extent of derivatization for dextran (18 kDa) was about 120 glucose units per DTPA, and for cellulose and starch about 15-30 units per DTPA. For spin-labeled polysaccharides, the average loading ranged from 1 nitroxide per 16 glucose units for starch to 181 for dextran (82 kDa). These derivatized paramagnetic polysaccharides were shown to be more effective relaxants than the small paramagnetic molecules alone. Both soluble and insoluble polysaccharide-linker-DTPA-Gd(3) complexes were effectively cleared from the body (rats) after oral administration. After intravenous administration, the biodistribution of dextran-linker-DTPA-Gd(3) complexes differed significantly from that of GdDTPA. Reduction of the nitroxide by ascorbic acid was retarded in the polysaccharide derivatives, particularly in starch derivatized with both nitroxide and linker-DTPA-Cu(2). These agents showed contrast enhancement in the gastrointestinal tract of rabbits.

Bligh, S.W.; Harding, C.T.; Sadler, P.J.; Bulman, R.A.; Bydder, G.M.; Pennock, J.M.; Kelly, J.D.; Latham, I.A.; Marriott, J.A. (Department of Chemistry, Birkbeck College, London (England))

1991-02-01

320

Representations of modality-specific affective processing for visual and auditory stimuli derived from functional magnetic resonance imaging data.  

PubMed

There is converging evidence that people rapidly and automatically encode affective dimensions of objects, events, and environments that they encounter in the normal course of their daily routines. An important research question is whether affective representations differ with sensory modality. This research examined the nature of the dependency of affect and sensory modality at a whole-brain level of analysis in an incidental affective processing paradigm. Participants were presented with picture and sound stimuli that differed in positive or negative valence in an event-related functional magnetic resonance imaging experiment. Global statistical tests, applied at a level of the individual, demonstrated significant sensitivity to valence within modality, but not valence across modalities. Modality-general and modality-specific valence hypotheses predict distinctly different multidimensional patterns of the stimulus conditions. Examination of lower dimensional representation of the data demonstrated separable dimensions for valence processing within each modality. These results provide support for modality-specific valence processing in an incidental affective processing paradigm at a whole-brain level of analysis. Future research should further investigate how stimulus-specific emotional decoding may be mediated by the physical properties of the stimuli. Hum Brain Mapp 35:3558-3568, 2014. © 2013 Wiley Periodicals, Inc. PMID:24302696

Shinkareva, Svetlana V; Wang, Jing; Kim, Jongwan; Facciani, Matthew J; Baucom, Laura B; Wedell, Douglas H

2014-07-01

321

Activatable fluorescent cys-diabody conjugated with indocyanine green derivative: consideration of fluorescent catabolite kinetics on molecular imaging  

PubMed Central

Abstract. Antibody fragments including diabodies have more desirable pharmacokinetic characteristics than whole antibodies. An activatable optical imaging probe based on a cys-diabody targeting prostate-specific membrane antigen conjugated with the near-infrared fluorophore, indocyanine green (ICG), was designed such that it can only be activated when bound to the tumor, leading to high signal-to-background ratios. We employed short polyethylene glycol (PEG) linkers between the ICG and the reactive functional group (Sulfo-OSu group), resulting in covalent conjugation of ICG to the cys-diabody, which led to lower dissociation of ICG from cys-diabody early after injection, reducing hepatic uptake. However, unexpectedly, high and long-term fluorescence was observed in the kidneys, liver, and blood pool more than 1 h after injection of the cys-diabody PEG-ICG conjugate. A biodistribution study using I125-labeled cys-diabody-ICG showed immediate uptake in the kidneys followed by a rapid decrease, while gastric activity increased due to released radioiodine during rapid cys-diabody-ICG catabolism in the kidneys. To avoid this catabolic pathway, it would be preferable to use antibody fragments large enough not to be filtered through glomerulus or to conjugate the fragments with fluorescent dyes that are readily excreted into urine when cleaved from the cys-diabody to achieve high tumor-specific detection.

Sano, Kohei; Nakajima, Takahito; Ali, Towhid; Bartlett, Derek W.; Wu, Anna M.; Kim, Insook; Paik, Chang H.; Choyke, Peter L.; Kobayashi, Hisataka

2013-01-01

322

The response of gross nitrogen mineralization to labile carbon inputs  

NASA Astrophysics Data System (ADS)

Input of labile carbon sources to forest soils commonly result in priming, i.e. an increase in the microbial decomposition of soil organic matter. Efforts aimed at quantifying the extent of priming have, to date, largely focused on soil organic matter decomposition manifested as soil respiration. Less is known about how gross nitrogen mineralization responds to input of labile carbon. It is often assumed that increased priming results in decreased soil carbon stocks. However, microbial mineralization of organic nitrogen into plant available forms is a major factor limiting primary production in forests. If increased decomposition of soil organic matter in response to labile carbon is accompanied by a concurrent increased nitrogen mineralization, this could result in elevated primary production and higher rates of plant derived organic matter input to soils. Therefore, in order to fully understand the effect of priming on net ecosystem exchange and soil carbon stocks, it is vital to consider if increased decomposition of soil organic matter caused by priming also results in increased nitrogen mineralization. Here I present the results from a series of experiments aimed at determining if, and to which extent, gross nitrogen mineralization is stimulated by input of labile carbon. The results suggest that it is by no means uncommon to find an increase in gross N mineralization rates in response to labile carbon inputs. The magnitude of the increase seems dependent on the nitrogen status of the soil, as well as the concentration and rate of labile carbon inputs. However, continuous input of labile carbon sources that also contains nitrogen, e.g. amino acids, seems to inhibit rather than increase the mineralization of organic nitrogen. These findings suggest that there is a potential for a positive feedback between priming and primary production that needs to be considered in order to fully understand the influence of priming on net ecosystem exchange and soil carbon stocks.

Bengtson, Per

2014-05-01

323

Honeybee navigation: odometry with monocular input.  

PubMed

Recent studies have revealed that navigating honeybees, Apis mellifera, estimate the distance to a food source by integrating over time the image motion that they experience en route. Here we examine the ability of honeybees to gauge distance travelled when visual input is available primarily to one eye. Bees were trained to fly into a tunnel, lined with textured patterns, to collect a reward at a feeder placed at a certain distance. Their ability to estimate distance flown was then assessed by testing them in a fresh tunnel without the feeder. The results show that (1) bees can estimate distance flown under monocular conditions, performing nearly as accurately as when information is available to both eyes; (2) bees can learn to fly two different distances, where each distance is measured in terms of the image motion experienced by a different eye; and (3) bees that have acquired information on the distance to a food source using one eye can measure out the same distance when they are required to use the other (naive) eye. The need to measure distance using signals from a single eye becomes important when a bee flies to a food source along the face of a cliff or the edge of a forest. Furthermore, under such conditions, it is important to be able to deal with odometric signals that are transposed interocularly when the bee returns home from the food source. This is because, although distances are learnt primarily on the way to a food source, foraging bees monitor distance flown on the homebound as well as the outbound routes. Copyright 1998 The Association for the Study of Animal Behaviour. PMID:9819342

Srinivasan; Zhang; Lehrer

1998-11-01

324

High affinity tamoxifen derivatives  

US Patent & Trademark Office Database

The synthesis of tamoxifen derivatives, most particularly halo, halo alkyl, hydroxy, and amino tamoxifen derivatives is disclosed. The native tamoxifen molecule includes a substituted chemical group positioned on the aliphatic chain of the tamoxifen molecule. Particular tamoxifen derivatives of the invention include chloro, bromo, iodo, fluoro, amino and DTPA tamoxifen derivatives, and corresponding lower alkyl halogenated forms. The halogenated tamoxifen derivatives possess superior binding affinities for estrogen receptor rich tissues, such as uterine tissue and breast tissue, relative to unsubstituted native tamoxifen. Radiolabeled forms of the tamoxifen derivatives may be used as highly specific imaging agents for estrogen receptor rich tissues. The fluoro and bromo tamoxifen derivatives are particularly useful for imaging estrogen receptors by PET whereas the iodinated tamoxifens are particularly useful in imaging estrogen receptors by SPECT. Rapid and efficient methods of preparing the tamoxifen derivatives having high specific activity (>6 Ci/.mu.mol) are also disclosed. Aliphatic chain substituted tamoxifen derivatives are shown to possess greater estrogen receptor binding affinity and more potent tumor cell inhibition than tamoxifen or tamoxifen derivatives substituted at other locations on the molecule (i.e., non-aliphatic chain substituted tamoxifen). The tanioxifen derivatives of the present invention may advantageously be used as anti-cancer therapeutic agents to halt estrogen-receptor positive tumors, such as those of breast and uterine tissue. The present invention also provides a hydrophilic DTPA-tamnoxifen analogue, and uses thereof in imaging estrogen receptor positive ER+ lesions.

2000-08-01

325

A storage model with self-similar input  

Microsoft Academic Search

A storage model with self-similar input process is studied. A relation coupling together the storage requirement, the achievable utilization and the output rate is derived. A lower bound for the complementary distribution function of the storage level is given. Keywords: Self-similar, fractional Brownian motion, Local Area Network traffic 1 Introduction In a series of papers (e.g. Leland [8], Leland and

Ilkka Norros

1994-01-01

326

Generation of input signals for ArF amplifiers  

Microsoft Academic Search

Four different schemes for the generation of femtosecond input pulses for ArF amplifiers are described. Pulse energies of 100 nJ were obtained with phase-matched frequency mixing of a Raman-shifted frequency-doubled pulse derived from a 537-nm femtosecond dye-laser pulse. Excellent spatial, spectral, and amplitude stability was obtained when a broadband, nanosecond dye laser at 690 nm was used as a Raman

S. Szatmári; F. P. Schäfer

1989-01-01

327

A Novel Gestural Input Device for Virtual Reality  

Microsoft Academic Search

The ImageGlove is 3D input device with six degrees-of-freedom that can be used to interface with non-immersive virtual environments. It is possible to detect the position and orientation of the human hand in real time. The author's device can be used as a wireless replacement for the Polhemus position sensor. The system allows one to use the human hand as

Christoph Maggioni; SIEMENS AG; Otto Hahn

1993-01-01

328

Spectral characterisation of the CARMENES input catalogue  

NASA Astrophysics Data System (ADS)

CARMENES (Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Échelle Spectrographs) is the future exoplanet hunter for the 3.5-m Calar Alto telescope. Its first light is expected to be in early 2014. For a sample of 312 M-type stars, we performed their spectral-type classification by comparing their low-resolution spectra with those of spectral-type standard stars acquired during the same observing runs, and using spectral indices well-calibrated for M dwarfs, such as, TiO5, CaH2 and CaH3. We also derived chromospheric activity indicators and relative metallicities. All these data were included in our ``input catalogue'', CARMENCITA (CARMENES Cool star Information and daTa Archive), which will be the most comprehensive catalogue on M dwarfs ever built. This database currently comprises the over 1300 brightest, latest M dwarfs northern of ? = -23 deg. Among them, we will select carefully the 300 most promising candidates that will be surveyed for low-mass planet companions by means of the analysis of high accuracy radial velocity measurements. Our URL: {http://carmenes.caha.es/}

Klutsch, A.; Alonso-Floriano, F. J.; Caballero, J. A.; Montes, D.; Cortés-Contreras, M.; López-Santiago, J.; Morales, J. C.; Quirrenbach, A.; Amado, P. J.; Ribas, I.; Reiners, A.; Mundt, R.

2012-12-01

329

Deriving surface motion of mountain glaciers in the Tuomuer-Khan Tengri Mountain Ranges from PALSAR images  

NASA Astrophysics Data System (ADS)

Glaciers flow velocity is an important parameter for the study of glacier dynamics, mass balance and climate change, and can provide precursory warning of glacier melting induced flooding, debris flowing, etc. The Tuomuer-Khan Tengri Mountain Range is one of the largest glaciated areas in Tian Shan Mountain. However, the knowledge of glacier motion in this area is still rather limited. Using the method of robust Offset-tracking and four pairs of PALSAR images covering the Tuomuer-Khan Tengri Mountain Range, this paper estimates the displacement fields of the mountain glaciers in this area for each pair. The displacement fields are then mapped into daily glacier flow velocities by dividing the acquiring intervals of each pair. Using a series of checkpoints selected in stationary areas where the displacements can be assumed to be zero, we evaluate the estimation error of the displacement fields and find that most of them are less than 2.17 cm/day. The displacement fields are analyzed in detail with regards to glacier bed terrain and glacial temperature and thickness. We find that they are in excellent accordance with the flow characteristic of typical mountain glaciers. The velocity changes among the observation years have been carefully examined. This along with the associated runoff measurements makes us conclude that the glaciers in the Tuomuer-Khan Tengri Range are assumedly in dynamic equilibrium between intensified melting and increased precipitation and glaciation, and their velocity will maintain stable in the near future. We also find that the altitudes of the velocity peaks are close to the recorded snowline, which indicates that detecting the changes of velocity peaks' position might provide a reference for monitoring the changes of the snowlines.

Li, Jia; Li, Zhiwei; Zhu, Jianjun; Ding, Xiaoli; Wang, Changcheng; Chen, Jianli

2013-02-01

330

Hyperpolarized 13C spectroscopic imaging informs on hypoxia-inducible factor-1 and Myc activity downstream of platelet-derived growth factor receptor  

PubMed Central

The recent development of hyperpolarized 13C magnetic resonance spectroscopic imaging (MRSI) provides a novel method for in-vivo metabolic imaging with potential applications for detection of cancer and response to treatment. Chemotherapy-induced apoptosis was shown to decrease the flux of hyperpolarized 13C-label from pyruvate to lactate due to depletion of NADH, the coenzyme of lactate dehydrogenase (LDH). In contrast, we show here that in PC-3MM2 tumors, inhibition of platelet-derived growth factor receptor with imatinib reduces the conversion of hyperpolarized pyruvate to lactate by lowering the expression of LDH itself. This was accompanied by reduced expression of vascular endothelial growth factor and glutaminase, and is likely mediated by reduced expression of their transcriptional factors hypoxia-inducible factor-1 and c-Myc. Our results indicate that hyperpolarized 13C MRSI could potentially detect the molecular effect of various cell-signaling inhibitors, thus providing a radiation-free method to predict tumor response.

Dafni, Hagit; Larson, Peder E.Z; Hu, Simon; Yoshihara, Hikari A.I.; Ward, Christopher S.; Venkatesh, Humsa S.; Wang, Chunsheng; Zhang, Xiaoliang; Vigneron, Daniel B.; Ronen, Sabrina M.

2010-01-01

331

A 18F-labeled saxitoxin derivative for in vivo PET-MR imaging of voltage-gated sodium channel expression following nerve injury.  

PubMed

Both chronic and neuropathic pain conditions are associated with increased expression of certain voltage-gated sodium ion channel (NaV) isoforms in peripheral sensory neurons. A method for noninvasive imaging of these channels could represent a powerful tool for investigating aberrant expression of NaV and its role in pain pathogenesis. Herein, we describe the synthesis and evaluation of a positron emission tomography (PET) radiotracer targeting NaVs, the design of which is based on the potent, NaV-selective inhibitor saxitoxin. Both autoradiography analysis of sciatic nerves excised from injured rats as well as whole animal PET-MR imaging demonstrate that a systemically administered [(18)F]-labeled saxitoxin derivative concentrates at the site of nerve injury, consistent with upregulated sodium channel expression following axotomy. This type of PET agent has potential use for serial monitoring of channel expression levels at injured nerves throughout wound healing and/or following drug treatment. Such information may be correlated with pain behavioral analyses to help shed light on the complex molecular processes that underlie pain sensation. PMID:24261833

Hoehne, Aileen; Behera, Deepak; Parsons, William H; James, Michelle L; Shen, Bin; Borgohain, Preeti; Bodapati, Deepika; Prabhakar, Archana; Gambhir, Sanjiv S; Yeomans, David C; Biswal, Sandip; Chin, Frederick T; Du Bois, J

2013-12-01

332

Drawing Updates From Derivations  

Microsoft Academic Search

We propose a method for satisfying update requests in deductive databases. The setting is a generalization of the view update problem in relational databases. Updates can be drawn from goals and input clauses in derivations that are rooted at the request. An update may be invalidated by negation or integrity constraints. Thus, it may be necessary to try other updates,

Hendrik Decker; Siemens ZFE

1990-01-01

333

FLIGHT TEST VALIDATION OF OPTIMAL INPUT DESIGN AND COMPARISON TO CONVENTIONAL INPUTS  

Microsoft Academic Search

A technique for designing optimal inputs for aerodynamic parameter estimation was flight tested on the F-18 High Angle of Attack Research Vehicle (HARV). Model parameter accuracies calculated from flight test data were compared on an equal basis for optimal input designs and conventional inputs at the same flight condition. In spite of errors in the a priori input design models

Eugene A. Morelli

1997-01-01

334

Global image analysis to determine suitability for text-based image personalization  

NASA Astrophysics Data System (ADS)

Lately, image personalization is becoming an interesting topic. Images with variable elements such as text usually appear much more appealing to the recipients. In this paper, we describe a method to pre-analyze the image and automatically suggest to the user the most suitable regions within an image for text-based personalization. The method is based on input gathered from experiments conducted with professional designers. It has been observed that regions that are spatially smooth and regions with existing text (e.g. signage, banners, etc.) are the best candidates for personalization. This gives rise to two sets of corresponding algorithms: one for identifying smooth areas, and one for locating text regions. Furthermore, based on the smooth and text regions found in the image, we derive an overall metric to rate the image in terms of its suitability for personalization (SFP).

Ding, Hengzhou; Bala, Raja; Fan, Zhigang; Bouman, Charles A.; Allebach, Jan P.

2012-02-01

335

Input filter compensation for switching regulators  

NASA Technical Reports Server (NTRS)

The problems caused by the interaction between the input filter, output filter, and the control loop are discussed. The input filter design is made more complicated because of the need to avoid performance degradation and also stay within the weight and loss limitations. Conventional input filter design techniques are then dicussed. The concept of pole zero cancellation is reviewed; this concept is the basis for an approach to control the peaking of the output impedance of the input filter and thus mitigate some of the problems caused by the input filter. The proposed approach for control of the peaking of the output impedance of the input filter is to use a feedforward loop working in conjunction with feedback loops, thus forming a total state control scheme. The design of the feedforward loop for a buck regulator is described. A possible implementation of the feedforward loop design is suggested.

Lee, F. C.; Kelkar, S. S.

1982-01-01

336

Computer Generated Inputs for NMIS Processor Verification  

Microsoft Academic Search

Proper operation of the Nuclear Identification Materials System (NMIS) processor can be verified using computer-generated inputs [BIST (Built-In-Self-Test)] at the digital inputs. Preselected sequences of input pulses to all channels with known correlation functions are compared to the output of the processor. These types of verifications have been utilized in NMIS type correlation processors at the Oak Ridge National Laboratory

J. A. Mullens; J. E. Breeding; J. A. McEvers; R. W. Wysor; L. G. Chiang; J. R. Lenarduzzi; J. T. Mihalczo; J. K. Mattingly

2001-01-01

337

Performance evaluation of input and output queueing techniques in ATM switching systems  

NASA Astrophysics Data System (ADS)

In this paper, alternatives to model a fast packet switching system are analyzed. A nonblocking switch fabric which runs at the same speed as the input/output links is considered. The performance of the considered approaches have been derived by theoretical analysis and computer simulations. Performance comparison between input queueing approaches with different selection policies are presented. Novel input and output queueing techniques are also proposed. In particular it is shown that, depending on the implementation, the novel input queueing approach studied in this paper achieves the same performance as the optimum (output) queueing alternative, without resorting to a faster packet switch fabric.

Delre, Enrico; Fantacci, Romano

1993-10-01

338

Document understanding using layout styles of title page images  

NASA Astrophysics Data System (ADS)

An important problem in the application of compound document architectures is the input of data from raster images. One technique is to use visual, syntactic cues found in the layout of the raster document to infer its logical structure or semantics. Another is to use context derived from characters recognized within a given block of raster data. Both character- and image- based information are considered here. A well-constrained environment is defined for use in developing rules that can be applied to basic book title page understanding. This paper identifies the attributes of title page layout objects which aid in mapping them into the fields of a simple bibliographic format. Using as input the raster images of the title page and the verso of the title page along with the ASCII output of a generic character recognition engine from these same images, a system of rules is defined for generating a marked-up text wherein key bibliographic fields may be identified.

Sharpe, Louis H., II; Manns, Basil

1992-08-01

339

Dynamic allocation for input redundant control systems  

Microsoft Academic Search

In this paper we address control systems with redundant actuators and characterize the concepts of weak and strong input redundancy. Based on this characterization, we propose a dynamic augmentation to a control scheme which performs the plant input allocation with the goal of employing each actuator in a suitable way, based on its magnitude and rate limits. The proposed theory

Luca Zaccarian

2009-01-01

340

VALID: A Routine to Validate Input Data.  

National Technical Information Service (NTIS)

The VALID computer program checks input data for conformance to user-defined specifications. A context-free grammer is used to specify the format character sequence, or numeric range for each category of input data. Data may be supplied as free-form text ...

W. T. Overman J. E. Ramus

1975-01-01

341

Effective Input Variable Selection for Function Approximation  

Microsoft Academic Search

Input variable selection is a key preprocess step in any I\\/O modelling problem. Normally, better generalization performance is ob- tained when unneeded parameters coming from irrelevant or redundant variables are eliminated. Information theory provides a robust theoretical framework for performing input variable selection thanks to the concept of mutual information. Nevertheless, for continuous variables, it is usu- ally a more

Luis Javier Herrera; Héctor Pomares; Ignacio Rojas; Michel Verleysen; Alberto Guillén

2006-01-01

342

Modality of Input and Vocabulary Acquisition  

ERIC Educational Resources Information Center

This study examines the effect of input modality (video, audio, and captions, i.e., on-screen text in the same language as audio) on (a) the learning of written and aural word forms, (b) overall vocabulary gains, (c) attention to input, and (d) vocabulary learning strategies of beginning L2 learners. Twenty-six second-semester learners of Russian…

Sydorenko, Tetyana

2010-01-01

343

Mercury inputs into the Amazon Region, Brazil  

Microsoft Academic Search

Mercury inputs into the Brazilian Amazon ecosystem due to goldmining activities are quantified based on data from various Brazilian Mineral and Environmental Agencies as well as field works. Total losses of Hg were estimated to be 1.32 kg Hg\\/kg Au from which 45% are released into rivers and 55% into the atmosphere. Total Hg input to the Amazon may contribute

W. C. Pfeiffer; L. Drude de Lacerda

1988-01-01

344

Control input shaping for coordinate measuring machines  

Microsoft Academic Search

Structural vibrations in coordinate measuring machines deteriorate measurement quality at high operating speeds. In this paper, a control strategy is presented that appropriately shapes inputs to a CMM motion controller in order to avoid exciting unwanted vibrations. This control strategy utilizes a traditional bang-bang trajectory and new filtering technique called the feedforward filter. The control input construction takes place in

Steven D. Jones; A. Galip Ulsoy

1994-01-01

345

Input, Interaction, and Second Language Production.  

ERIC Educational Resources Information Center

This study investigated the relationship among input, interaction, and second-language production among 16 native-nonnative dyads. The results indicated that both modified input and interaction initiated by the native speaker lead to greater comprehension by the nonnative speaker, as measured by task performance. (Contains 48 references.) (MDM)

Gass, Susan M.; Varonis, Evangeline Marlos

1994-01-01

346

The Input Hypothesis: An Inside Look.  

ERIC Educational Resources Information Center

Summarizes and discusses Krashen's "input hypothesis" as presented in his "Principles and Practice in Second Language Acquisition." Suggests that the input hypothesis fails to account convincingly for arrested second language acquisition in an acquisition-rich environment and that it is not directly applicable to U.S. high school and university…

Higgs, Theodore V.

1985-01-01

347

FURTHER FACTS ABOUT INPUT TO STATE STABILIZATION  

Microsoft Academic Search

Previous results about input to state stabilizability are shown to hold even for systems which are not linear in controls, provided that a more general type of feedback be allowed. Applications to certain stabilization problems and coprime factorizations, as well as comparisons to other results on input to state stability, are also briefly discussed.

Eduardo D. Sontag

1989-01-01

348

Revisiting keratoconus diagnosis and progression classification based on evaluation of corneal asymmetry indices, derived from Scheimpflug imaging in keratoconic and suspect cases  

PubMed Central

Purpose To survey the standard keratoconus grading scale (Pentacam®-derived Amsler–Krumeich stages) compared to corneal irregularity indices and best spectacle-corrected distance visual acuity (CDVA). Patients and methods Two-hundred and twelve keratoconus cases were evaluated for keratoconus grading, anterior surface irregularity indices (measured by Pentacam imaging), and subjective refraction (measured by CDVA). The correlations between CDVA, keratometry, and the Scheimpflug keratoconus grading and the seven anterior surface Pentacam-derived topometric indices – index of surface variance, index of vertical asymmetry, keratoconus index, central keratoconus index, index of height asymmetry, index of height decentration, and index of minimum radius of curvature – were analyzed using paired two-tailed t-tests, coefficient of determination (r2), and trendline linearity. Results The average ± standard deviation CDVA (expressed decimally) was 0.626 ± 0.244 for all eyes (range 0.10–1.00). The average flat meridian keratometry was (K1) 46.7 ± 5.89 D; the average steep keratometry (K2) was 51.05 ± 6.59 D. The index of surface variance and the index of height decentration had the strongest correlation with topographic keratoconus grading (P < 0.001). CDVA and keratometry correlated poorly with keratoconus severity. Conclusion It is reported here for the first time that the index of surface variance and the index of height decentration may be the most sensitive and specific criteria in the diagnosis, progression, and surgical follow-up of keratoconus. The classification proposed herein may present a novel benchmark in clinical work and future studies.

John, Anastasios Kanellopoulos; Asimellis, George

2013-01-01

349

Response of traveling waves to transient inputs in neural fields.  

PubMed

We analyze the effects of transient stimulation on traveling waves in neural field equations. Neural fields are modeled as integro-differential equations whose convolution term represents the synaptic connections of a spatially extended neuronal network. The adjoint of the linearized wave equation can be used to identify how a particular input will shift the location of a traveling wave. This wave response function is analogous to the phase response curve of limit cycle oscillators. For traveling fronts in an excitatory network, the sign of the shift depends solely on the sign of the transient input. A complementary estimate of the effective shift is derived using an equation for the time-dependent speed of the perturbed front. Traveling pulses are analyzed in an asymmetric lateral inhibitory network and they can be advanced or delayed, depending on the position of spatially localized transient inputs. We also develop bounds on the amplitude of transient input necessary to terminate traveling pulses, based on the global bifurcation structure of the neural field. PMID:22463247

Kilpatrick, Zachary P; Ermentrout, Bard

2012-02-01

350

Statistical identification of effective input variables. [SCREEN  

SciTech Connect

A statistical sensitivity analysis procedure has been developed for ranking the input data of large computer codes in the order of sensitivity-importance. The method is economical for large codes with many input variables, since it uses a relatively small number of computer runs. No prior judgemental elimination of input variables is needed. The sceening method is based on stagewise correlation and extensive regression analysis of output values calculated with selected input value combinations. The regression process deals with multivariate nonlinear functions, and statistical tests are also available for identifying input variables that contribute to threshold effects, i.e., discontinuities in the output variables. A computer code SCREEN has been developed for implementing the screening techniques. The efficiency has been demonstrated by several examples and applied to a fast reactor safety analysis code (Venus-II). However, the methods and the coding are general and not limited to such applications.

Vaurio, J.K.

1982-09-01

351

Input, innateness, and induction in language acquisition.  

PubMed

Input and innateness compliment one another in language acquisition. Children exposed to different languages acquire different languages. Children's language experience, however, underdetermines the grammars that they acquire; the constraints that are not supplied by input must be available endogenously, and the ultimate origin of these endogenous contributions to acquisition may be traced to the biology of the mind. To the extent that assumptions of innateness encourage greater explicitness in the formulation of theories of acquisition, they should be welcomed. Excessively powerful assumptions of innateness may not be subject to empirical disconfirmation, however. Therefore, attention should be devoted to the development of a theory of language input, particularly with regard to identifying invariants of input. In combination with a linguistic theory providing an account of the endstate of acquisition, a theory of input would permit the deduction of properties of the mind that underlie the acquisition of language. PMID:2286297

Morgan, J L

1990-11-01

352

Metamodelling with independent and dependent inputs  

NASA Astrophysics Data System (ADS)

In the cases of computationally expensive models the metamodelling technique which maps inputs and outputs is a very useful and practical way of making computations tractable. A number of new techniques which improve the efficiency of the Random Sampling-High dimensional model representation (RS-HDMR) for models with independent and dependent input variables are presented. Two different metamodelling methods for models with dependent input variables are compared. Both techniques are based on a Quasi Monte Carlo variant of RS-HDMR. The first technique makes use of transformation of the dependent input vector into a Gaussian independent random vector and then applies the decomposition of the model using a tensored Hermite polynomial basis. The second approach uses a direct decomposition of the model function into a basis which consists of the marginal distributions of input components and their joint distribution. For both methods the copula formalism is used. Numerical tests prove that the developed methods are robust and efficient.

Zuniga, M. Munoz; Kucherenko, S.; Shah, N.

2013-06-01

353

Measuring Input Thresholds on an Existing Board  

NASA Technical Reports Server (NTRS)

A critical PECL (positive emitter-coupled logic) interface to Xilinx interface needed to be changed on an existing flight board. The new Xilinx input interface used a CMOS (complementary metal-oxide semiconductor) type of input, and the driver could meet its thresholds typically, but not in worst-case, according to the data sheet. The previous interface had been based on comparison with an external reference, but the CMOS input is based on comparison with an internal divider from the power supply. A way to measure what the exact input threshold was for this device for 64 inputs on a flight board was needed. The measurement technique allowed an accurate measurement of the voltage required to switch a Xilinx input from high to low for each of the 64 lines, while only probing two of them. Directly driving an external voltage was considered too risky, and tests done on any other unit could not be used to qualify the flight board. The two lines directly probed gave an absolute voltage threshold calibration, while data collected on the remaining 62 lines without probing gave relative measurements that could be used to identify any outliers. The PECL interface was forced to a long-period square wave by driving a saturated square wave into the ADC (analog to digital converter). The active pull-down circuit was turned off, causing each line to rise rapidly and fall slowly according to the input s weak pull-down circuitry. The fall time shows up as a change in the pulse width of the signal ready by the Xilinx. This change in pulse width is a function of capacitance, pulldown current, and input threshold. Capacitance was known from the different trace lengths, plus a gate input capacitance, which is the same for all inputs. The pull-down current is the same for all inputs including the two that are probed directly. The data was combined, and the Excel solver tool was used to find input thresholds for the 62 lines. This was repeated over different supply voltages and temperatures to show that the interface had voltage margin under all worst case conditions. Gate input thresholds are normally measured at the manufacturer when the device is on a chip tester. A key function of this machine was duplicated on an existing flight board with no modifications to the nets to be tested, with the exception of changes in the FPGA program.

Kuperman, Igor; Gutrich, Daniel G.; Berkun, Andrew C.

2011-01-01

354

Intravoxel incoherent motion MR imaging for prostate cancer: an evaluation of perfusion fraction and diffusion coefficient derived from different b-value combinations.  

PubMed

There has been a resurgent interest in intravoxel incoherent motion (IVIM) MR imaging to obtain perfusion as well as diffusion information on lesions, in which the diffusion was modeled as Gaussian diffusion. However, it was observed that this diffusion deviated from expected monoexponential decay at high b-values and the reported perfusion in prostate is contrary to the findings in dynamic contrast-enhanced (DCE) MRI studies and angiogenesis. Thus, this work is to evaluate the effect of different b-values on IVIM perfusion fractions (f) and diffusion coefficients (D) for prostate cancer detection. The results show that both parameters depended heavily on the b-values, and those derived without the highest b-value correlated best with the results from DCE-MRI studies; specifically, f was significantly elevated (7.2% vs. 3.7%) in tumors when compared with normal tissues, in accordance with the volume transfer constant (K(trans); 0.39 vs. 0.18 min(-1)) and plasma fractional volume (v(p) ; 8.4% vs. 3.4%). In conclusion, it is critical to choose an appropriate range of b-values in studies or include the non-Gaussian diffusion contribution to obtain unbiased IVIM measurements. These measurements could eliminate the need for DCE-MRI, which is especially relevant in patients who cannot receive intravenous gadolinium-based contrast media. PMID:22488794

Pang, Yuxi; Turkbey, Baris; Bernardo, Marcelino; Kruecker, Jochen; Kadoury, Samuel; Merino, Maria J; Wood, Bradford J; Pinto, Peter A; Choyke, Peter L

2013-02-01

355

Synthesis and evaluation of novel (18)F-labeled spirocyclic piperidine derivatives as ?1 receptor ligands for positron emission tomography imaging.  

PubMed

A series of spirocyclic piperidine derivatives were designed and synthesized as ?1 receptor ligands. In vitro competition binding assays showed that 1'-(4-(2-fluoroethoxy)benzyl)-3H-spiro[2-benzofuran-1,4'-piperidine] (19) possessed high ?1 receptor affinity (Ki = 0.79 nM) and excellent ?1/?2 subtype selectivity (350-fold) as well as high ?1/VAChT selectivity (799-fold). The radiolabeled compound [(18)F]19 was synthesized by substitution of the tosylate precursor 24 with [(18)F]fluoride, with an isolated radiochemical yield of 35-60%, a radiochemical purity of >99%, and a specific activity of 30-55 GBq/?mol. Biodistribution studies in imprinting control region mice indicated that [(18)F]19 displayed excellent initial brain uptake and slow washout. Ex vivo autoradiography in Sprague-Dawley rats demonstrated high accumulation of the radiotracer in brain areas known to express high levels of ?1 receptors. Micro positron emission tomography imaging and blocking studies confirmed the specific binding of [(18)F]19 to ?1 receptors in vivo. PMID:23566245

Li, Yan; Wang, Xia; Zhang, Jinming; Deuther-Conrad, Winnie; Xie, Fang; Zhang, Xiaojun; Liu, Jian; Qiao, Jinping; Cui, Mengchao; Steinbach, Jörg; Brust, Peter; Liu, Boli; Jia, Hongmei

2013-05-01

356

Spatial distribution of stabilizer-derived nitroxide radicals during thermal degradation of poly(acrylonitrile-butadiene-styrene) copolymers: a unified picture from pulsed ELDOR and ESR imaging.  

PubMed

Double Electron-Electron Resonance (DEER) provides information on the spatial distribution of radicals on the length scale of a few nanometres, while Electron Spin Resonance Imaging (ESRI) provides information on a length scale of millimetres with a resolution of about 100 micrometres. Despite the gap between these length scales, results from the two techniques are found to complement and support each other in the characterization of the identity and distribution of nitroxide radicals derived from the Hindered Amine Stabilizer (HAS) Tinuvin 770 in poly(acrylonitrile-butadiene-styrene) (ABS) copolymers. DEER measurements demonstrate that there is no significant formation of biradicals from the bifunctional HAS, and provide the distributions of local radical concentrations. These distributions are poorly resolved for model-free analysis of the DEER data by the Tikhonov regularization; the resolution was significantly improved by utilizing information obtained by ESRI. DEER data can be fitted with only one adjustable parameter, namely the average radical concentration, if 1D and 2D spectral--spatial ESRI results on both the spatial distribution of nitroxides and their distribution between the acrylonitrile--styrene-rich (SAN) and butadiene-rich (B) microphases are considered. PMID:17028698

Jeschke, Gunnar; Schlick, Shulamith

2006-09-21

357

Detection and localization of novel hordatine-like compounds and glycosylated derivates of hordatines by imaging mass spectrometry of barley seeds.  

PubMed

Mass spectrometry imaging was applied on germinated barley for the detailed localization of metabolites in longitudinal and transversal seed sections. Among others, 20 m/z signals occurred in three regular peak clusters with specific, distinct localizations in embryo tissues. High resolution FT-ICR MS, MALDI-TOF MS/MS, and UHPLC-ESI MS/MS served for the identification and structural characterization of these compounds. Only five metabolites were published in their structures, namely the antifungal compounds hordatine A and B in non-glycosylated and glycosylated forms. All other non-identified cluster compounds were of hordatine-like structure and differed by systematic O-methylations, hydroxylations, and glycosylations. These differences in molecular structures correlated to distinct localization patterns within the embryo and might serve for the regulation of antifungal properties. Based on the structural investigations by mass spectrometry, an array of different hordatines that comprises the five published hordatines, 15 novel hordatine derivates and their six precursors could be localized in the embryo of germinated barley. Implications for the biosynthetic pathway and transport processes are discussed. PMID:24671626

Gorzolka, Karin; Bednarz, Hanna; Niehaus, Karsten

2014-06-01

358

Kernel principal component analysis for stochastic input model generation  

NASA Astrophysics Data System (ADS)

Stochastic analysis of random heterogeneous media provides useful information only if realistic input models of the material property variations are used. These input models are often constructed from a set of experimental samples of the underlying random field. To this end, the Karhunen-Loève (K-L) expansion, also known as principal component analysis (PCA), is the most popular model reduction method due to its uniform mean-square convergence. However, it only projects the samples onto an optimal linear subspace, which results in an unreasonable representation of the original data if they are non-linearly related to each other. In other words, it only preserves the first-order (mean) and second-order statistics (covariance) of a random field, which is insufficient for reproducing complex structures. This paper applies kernel principal component analysis (KPCA) to construct a reduced-order stochastic input model for the material property variation in heterogeneous media. KPCA can be considered as a nonlinear version of PCA. Through use of kernel functions, KPCA further enables the preservation of higher-order statistics of the random field, instead of just two-point statistics as in the standard Karhunen-Loève (K-L) expansion. Thus, this method can model non-Gaussian, non-stationary random fields. In this work, we also propose a new approach to solve the pre-image problem involved in KPCA. In addition, polynomial chaos (PC) expansion is used to represent the random coefficients in KPCA which provides a parametric stochastic input model. Thus, realizations, which are statistically consistent with the experimental data, can be generated in an efficient way. We showcase the methodology by constructing a low-dimensional stochastic input model to represent channelized permeability in porous media.

Ma, Xiang; Zabaras, Nicholas

2011-08-01

359

Linear methods for input scenes restoration from signals of optical-digital pattern recognition correlator  

NASA Astrophysics Data System (ADS)

Linear methods of restoration of input scene's images in optical-digital correlators are described. Relatively low signal to noise ratio of a camera's photo sensor and extensional PSF's size are special features of considered optical-digital correlator. RAW-files of real correlation signals obtained by digital photo sensor were used for input scene's images restoration. It is shown that modified evolution method, which employs regularization by Tikhonov, is better among linear deconvolution methods. As a regularization term, an inverse signal to noise ratio as a function of spatial frequencies was used. For additional improvement of restoration's quality, noise analysis of boundary areas of the image to be reconstructed was performed. Experimental results on digital restoration of input scene's images are presented.

Starikov, Sergey N.; Konnik, Mikhail V.; Manykin, Edward A.; Rodin, Vladislav G.

2009-04-01

360

Relative input strength rapidly regulates dendritic structure of chick auditory brainstem neurons.  

PubMed

Competition between presynaptic inputs has been suggested to shape dendritic form. This hypothesis can be directly tested on bitufted, auditory neurons in chicken nucleus laminaris (NL). Each NL neuron contains two relatively symmetrical dendritic arbors; the dorsal dendrites receive excitatory glutamatergic input from the ipsilateral ear, and the ventral dendrites receive corresponding input from the contralateral ear. To assess the effect of relative synaptic strength on NL dendrites, we used single-cell electroporation; electrophysiology; and live, two-photon laser scanning microscopy to manipulate both the amount and the balance of synaptic input to the two matching sets of dendrites. With simultaneous activation, both sets of dendrites changed together, either growing or retracting over the imaging period. In contrast, stimulation of only one set of dendrites (either dorsal or ventral) resulted in the unstimulated dendrites losing total dendritic branch length, whereas the stimulated dendrites exhibited a tendency to grow. In this system, balanced input leads to balanced changes in the two sets of dendrites, but imbalanced input results in differential changes. Time-lapse imaging revealed that NL dendrites respond to differential stimulation by first decreasing the size of their unstimulated dendrites and then increasing the size of their stimulated dendrites. This result suggests that the relative activity of presynaptic neurons dynamically controls dendritic structure in NL and that dendritic real estate can rapidly be shifted from inactive inputs to active inputs. PMID:21500196

Sorensen, Staci A; Rubel, Edwin W

2011-10-01

361

Kernel principal component analysis for stochastic input model generation  

SciTech Connect

Highlights: {yields} KPCA is used to construct a reduced order stochastic model of permeability. {yields} A new approach is proposed to solve the pre-image problem in KPCA. {yields} Polynomial chaos is used to provide a parametric stochastic input model. {yields} Flow in porous media with channelized permeability is considered. - Abstract: Stochastic analysis of random heterogeneous media provides useful information only if realistic input models of the material property variations are used. These input models are often constructed from a set of experimental samples of the underlying random field. To this end, the Karhunen-Loeve (K-L) expansion, also known as principal component analysis (PCA), is the most popular model reduction method due to its uniform mean-square convergence. However, it only projects the samples onto an optimal linear subspace, which results in an unreasonable representation of the original data if they are non-linearly related to each other. In other words, it only preserves the first-order (mean) and second-order statistics (covariance) of a random field, which is insufficient for reproducing complex structures. This paper applies kernel principal component analysis (KPCA) to construct a reduced-order stochastic input model for the material property variation in heterogeneous media. KPCA can be considered as a nonlinear version of PCA. Through use of kernel functions, KPCA further enables the preservation of higher-order statistics of the random field, instead of just two-point statistics as in the standard Karhunen-Loeve (K-L) expansion. Thus, this method can model non-Gaussian, non-stationary random fields. In this work, we also propose a new approach to solve the pre-image problem involved in KPCA. In addition, polynomial chaos (PC) expansion is used to represent the random coefficients in KPCA which provides a parametric stochastic input model. Thus, realizations, which are statistically consistent with the experimental data, can be generated in an efficient way. We showcase the methodology by constructing a low-dimensional stochastic input model to represent channelized permeability in porous media.

Ma Xiang [Materials Process Design and Control Laboratory, Sibley School of Mechanical and Aerospace Engineering, 101 Frank H.T. Rhodes Hall, Cornell University, Ithaca, NY 14853-3801 (United States); Zabaras, Nicholas, E-mail: zabaras@cornell.edu [Materials Process Design and Control Laboratory, Sibley School of Mechanical and Aerospace Engineering, 101 Frank H.T. Rhodes Hall, Cornell University, Ithaca, NY 14853-3801 (United States)

2011-08-10

362

Software for Device-Independent Graphical Input.  

National Technical Information Service (NTIS)

A three-level model and a graphics software structure based on the model that was developed with the goal of making graphical applications independent of the input devices are described. The software structure makes graphical applications independent of t...

G. Hamlin

1982-01-01

363

Analytical derivation of distortion constraints and their verification in a learning vector quantization-based target recognition system  

NASA Astrophysics Data System (ADS)

We obtain a novel analytical derivation for distortion-related constraints in a neural network- (NN)-based automatic target recognition (ATR) system. We obtain two types of constraints for a realistic ATR system implementation involving 4-f correlator architecture. The first constraint determines the relative size between the input objects and input correlation filters. The second constraint dictates the limits on amount of rotation, translation, and scale of input objects for system implementation. We exploit these constraints in recognition of targets varying in rotation, translation, scale, occlusion, and the combination of all of these distortions using a learning vector quantization (LVQ) NN. We present the simulation verification of the constraints using both the gray-scale images and Defense Advanced Research Projects Agency's (DARPA's) Moving and Stationary Target Recognition (MSTAR) synthetic aperture radar (SAR) images with different depression and pose angles.

Iftekharuddin, Khan M.; Razzaque, Mohammad A.

2005-06-01

364

Input\\/Output Compatibility of Reactive Systems  

Microsoft Academic Search

The notion of I\\/O compatibility of reactive systems is defined. It models the fact that two systems can be connected and establish\\u000a a correct dialogue through their input and output events. I\\/O compatibility covers safeness and liveness properties that can\\u000a be checked with a polynomial-time decision procedure. The relationship between observational equivalence, I\\/O compatibility\\u000a and input properness is also studied

Josep Carmona; Jordi Cortadella

2002-01-01

365

Research on configuration of antenna input regions  

NASA Astrophysics Data System (ADS)

A method is proposed for the analysis of the antenna input region for rotationally symmetric antennas. The mathematical formulation is an integrodifferential equation obtained from the potential integrals and boundary conditions. The solution is obtained by the method of moments, and the results are expressed in terms of generalized network parameters. Using this method, tapered transmission line feed configurations were analyzed theoretically, and both the current distributions and the input admittance are presented. The analysis was validated by a comparison with experimental results.

Hu, Xiaofeng; Yang, Yuan

366

Capture-based Automated Test Input Generation  

Microsoft Academic Search

Testing object-oriented software is critical because object-oriented languages have been commonly used in developing modern software systems. Many efficient test input generation techniques for object-oriented software have been proposed; however, state-of-the-art algorithms yield very low code coverage (e.g., less than 50%) on large-scale software. Therefore, one important and yet challenging problem is to generate desirable input objects for receivers and

Hojun Jaygarl

2010-01-01

367

Stereo vision based 3D input device  

Microsoft Academic Search

This paper concerns extracting 3D motion information from a 3D input device in real time focused to enabling effective human-computer. interaction. In particular, we develop a novel algorithm for extracting 6 degrees-of-freedom motion information from a 3D input device by employing an epipolar geometry of stereo camera, color, motion, and structure information, free from requiring the aid of camera calibration

SangMin Yoon; Ig-Jae Kim; Sang Chul Ahn; H. Ko; HyoungGon Kim

2002-01-01

368

3D input for 3D worlds  

Microsoft Academic Search

Virtual Worlds present a 3D space to the user. However, input devices are typically 2D. This unnatural mapping reduces the engagement of the experience. We are exploring using Wii controllers to provide 3D gesture-based input to the 3D virtual world, Second Life. By evaluating its usability, we found that gesture-based interfaces are appealing and natural for hand gestures such as

Sreeram Sreedharan; Edmund S. Zurita; Beryl Plimmer

2007-01-01

369

Subnanosecond protection circuits for oscilloscope inputs  

Microsoft Academic Search

Overvoltage protection circuits have been developed to protect oscilloscope inputs or other 50-? recording systems from fast (?r?1 ns) rise-time pulses. These circuits are voltage dividers with linear output up to a specified level, typically 1.4 V, beyond which fast switching diodes limit the output to ≲5 V for inputs as high as 5 kV. The clipping circuits are frequency

G. R. Mitchel

1985-01-01

370

Synthesis and preclinical evaluation of a new C-6 alkylated pyrimidine derivative as a PET imaging agent for HSV1-tk gene expression.  

PubMed

[(18)F]FHOMP (6-((1-[(18)F]-fluoro-3-hydroxypropan-2-yloxy)methyl)-5-methylpyrimidine-2,4(1H,3H)-dione), a C-6 substituted pyrimidine derivative, has been synthesized and evaluated as a potential PET agent for imaging herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene expression. [(18)F]FHOMP was prepared by the reaction of the tosylated precursor with tetrabutylammonium [(18)F]-fluoride followed by acidic cleavage of the protecting groups. In vitro cell accumulation of [(18)F]FHOMP and [(18)F]FHBG (reference) was studied with HSV1-tk transfected HEK293 (HEK293TK+) cells. Small animal PET and biodistribution studies were performed with HEK293TK+ xenograft-bearing nude mice. The role of equilibrative nucleoside transporter 1 (ENT1) in the transport and uptake of [(18)F] FHOMP was also examined in nude mice after treatment with ENT1 inhibitor nitrobenzylmercaptopurine ribonucleoside phosphate (NBMPR-P). [(18)F]FHOMP was obtained in a radiochemical yield of ~25% (decay corrected) and the radiochemical purity was greater than 95%. The uptake of [(18)F]FHOMP in HSV1-TK containing HEK293TK+ cells was 52 times (at 30 min) and 244 times (at 180 min) higher than in control HEK293 cells. The uptake ratios between HEK293TK+ and HEK293 control cells for [(18)F]FHBG were significantly lower i.e. 5 (at 30 min) and 81 (240 min). In vivo, [(18)F]FHOMP accumulated to a similar extend in HEK293TK+ xenografts as [(18)F]FHBG but with a higher general background. Blocking of ENT1 reduced [(18)F]FHOMP uptake into brain from a standardized uptake value (SUV) of 0.10±0.01 to 0.06±0.02, but did not reduce the general background signal in PET. Although [(18)F]FHOMP does not outperform [(18)F]FHBG in its in vivo performance, this novel C-6 pyrimidine derivative may be a useful probe for monitoring HSV1-tk gene expression in vivo. PMID:23342302

Müller, Ursina; Ross, Tobias L; Ranadheera, Charlene; Slavik, Roger; Müller, Adrienne; Born, Mariana; Trauffer, Evelyn; Sephton, Selena Milicevic; Scapozza, Leonardo; Krämer, Stefanie D; Ametamey, Simon M

2013-01-01

371

Input filter compensation for switching regulators  

NASA Technical Reports Server (NTRS)

A novel input filter compensation scheme for a buck regulator that eliminates the interaction between the input filter output impedance and the regulator control loop is presented. The scheme is implemented using a feedforward loop that senses the input filter state variables and uses this information to modulate the duty cycle signal. The feedforward design process presented is seen to be straightforward and the feedforward easy to implement. Extensive experimental data supported by analytical results show that significant performance improvement is achieved with the use of feedforward in the following performance categories: loop stability, audiosusceptibility, output impedance and transient response. The use of feedforward results in isolating the switching regulator from its power source thus eliminating all interaction between the regulator and equipment upstream. In addition the use of feedforward removes some of the input filter design constraints and makes the input filter design process simpler thus making it possible to optimize the input filter. The concept of feedforward compensation can also be extended to other types of switching regulators.

Kelkar, S. S.; Lee, F. C.

1983-01-01

372

A simple processing method allowing comparison of renal enhancing volumes derived from standard portal venous phase contrast-enhanced multidetector CT images to derive a CT estimate of differential renal function with equivalent results to nuclear medicine quantification  

Microsoft Academic Search

As iodinated contrast medium is cleared by glomerular filtration, it should be possible to apply the same principles utilized in radionuclide studies to derive differential renal function by comparison of enhancing renal volumes derived from contrast enhanced multidetector CT (CEMDCT). Having established a technique iteratively which appeared successful, a retrospective study was performed using 25 consecutive patients with a wide

J C Fowler; C Beadsmoore; M T G Gaskarth; H K Cheow; R Bernal; P Hegarty; K N Bullock; H Taylor; A K Dixon; A M Peters

2006-01-01

373

Contribution of dust inputs to dissolved organic carbon and water transparency in Mediterranean reservoirs  

NASA Astrophysics Data System (ADS)

Mediterranean reservoirs receive frequent Saharan dust inputs with soil-derived organic compounds mostly during stratification periods, when run-off inputs are particularly limited. Here, we quantified and optically characterized the water-soluble organic carbon (WSOC) of the (dry and wet) atmospheric deposition in collectors located near three reservoirs from the Western Mediterranean Basin. In addition, we determined, during the stratification period, the WSOC contribution to the pool of dissolved organic carbon (DOC) and the influence of the chromophoric organic compounds from the dust on water transparency. We found synchrony both in the WSOC atmospheric inputs among collectors and in the DOC dynamics among the three reservoirs. DOC concentrations and WSOC atmospheric inputs were positive and significantly correlated in the two reservoirs more sensitive to atmospheric inputs: the most oligotrophic reservoir (Quentar) and the reservoir with the highest ratio of surface area to mixing water depth (Cubillas). Nevertheless, WSOC atmospheric inputs, during the stratification period, represented less than 10 % of the total DOC pool, suggesting that indirect effects of dust inputs such as primary productivity stimulation may also induce these synchronic patterns. Chromophoric compounds from dust inputs can significantly reduce water transparency to ultraviolet radiation (UVR). The depths where UVR at ? = 320 nm is reduced to ten percent of surface intensity (Z10 %) decreased 15 cm (about 24 %) in Beznar, 17 cm (about 27 %) in Cubillas, and 43 cm (about 39 %) in Quéntar due to dust inputs.

de Vicente, I.; Ortega-Retuerta, E.; Morales-Baquero, R.; Reche, I.

2012-07-01

374

Radiative forcing by aerosols over the Bay of Bengal region derived from shipborne, island-based, and satellite (Moderate-Resolution Imaging Spectroradiometer) observations  

NASA Astrophysics Data System (ADS)

Measurements of spectral aerosol optical depths (AODs) were made over the Bay of Bengal region (adjacent to the Indian landmass) on board the oceanographic research vessel Sagar Kanya during February 2003. Simultaneous measurements of spectral AODs and mass concentrations of the composite aerosols and aerosol black carbon (BC) were made at an island location, Port Blair (11.63°N, 92.71°E), also in the Bay of Bengal. At the cruise locations the AODs were in the range of ˜0.3-0.6 at 500 nm (with a mean value of 0.41 ± 0.14) and Angstrom wavelength exponent of ˜1.1 ± 0.1; while at Port Blair the AODs were in the range of 0.11-0.48 at 500 nm and Angstrom wavelength exponent of 0.98 ± 0.07. Aerosol BC constituted 5.8 ± 0.6% of the composite aerosol mass concentration with a single-scattering albedo of ˜0.88, indicating the presence of a significant amount of submicron absorbing aerosols. Comparisons of AODs measured at Port Blair during cruise 188 and an earlier cruise (cruise 161B) during March 2001 (over the Bay of Bengal, Arabian Sea, and Indian Ocean) with those derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) (on board the TERRA platform) showed excellent agreement with a mean difference of ˜0.01 and a root-mean-square difference of ˜0.03. Regionally averaged aerosol (net) forcing over the Bay of Bengal was in the range -15 to -24 W m-2 at the surface and -2 to -4 W m-2 at the top of the atmosphere in February 2003; these values were smaller in magnitude than those observed over this region during March 2001 and larger than that observed over the Arabian Sea and the Indian Ocean. The resulting atmospheric heating due to aerosol absorption was ˜0.5°K/d.

Vinoj, V.; Babu, S. Suresh; Satheesh, S. K.; Moorthy, K.; Kaufman, Y. J.

2004-03-01

375

[Flow-sensitive in-vivo 4D MR imaging at 3T for the analysis of aortic hemodynamics and derived vessel wall parameters].  

PubMed

Modern phase contrast MR imaging at 3 Tesla allows the depiction of 3D morphology as well as the acquisition of time-resolved blood flow velocities in 3 directions. In combination with state-of-the-art visualization and data processing software, the qualitative and quantitative analysis of hemodynamic changes associated with vascular pathologies is possible. The 4D nature of the acquired data permits free orientation within the vascular system of interest and offers the opportunity to quantify blood flow and derived vessel wall parameters at any desired location within the data volume without being dependent on predefined 2D slices. The technique has the potential of overcoming the limitations of current diagnostic strategies and of implementing new diagnostic parameters. In light of the recent discussions regarding the influence of the wall shear stress and the oscillatory shear index on the genesis of arteriosclerosis and dilatative vascular processes, flow-sensitive 4D MRI may provide the missing diagnostic link. Instead of relying on experience-based parameters such as aneurysm size, new hemodynamic considerations can deepen our understanding of vascular pathologies. This overview reviews the underlying methodology at 3T, the literature on time-resolved 3D MR velocity mapping, and presents case examples. By presenting the pre- and postoperative assessment of hemodynamics in a thoracic aortic aneurysm and the detailed analysis of blood flow in a patient with coarctation we underline the potential of time-resolved 3D phase contrast MR at 3T for hemodynamic assessment of vascular pathologies, especially in the thoracic aorta. PMID:17436180

Frydrychowicz, A; Markl, M; Harloff, A; Stalder, A F; Bock, J; Bley, T A; Berger, A; Russe, M F; Schlensak, C; Hennig, J; Langer, M

2007-05-01

376

Input-output gains for signal in noise in stochastic resonance  

Microsoft Academic Search

A theoretical model for the transmission of a periodic signal added to a noise through a static nonlinearity is considered. Expressions are derived for the gains experienced by the signal, the noise and the signal-to-noise ratio in the input-output nonlinear transmission. The gains are obtained in the presence of a periodic input, a noise distribution and a static nonlinearity, all

François Chapeau-Blondeau

1997-01-01

377

Improved linear soft-input soft-output detection via soft feedback successive interference cancellation  

Microsoft Academic Search

We propose an improved minimum mean square error (MMSE) vertical Bell Labs layered space-time (V-BLAST) detection technique, called a soft input, soft output, and soft feedback (SIOF) V-BLAST detector, for turbo multi-input multioutput (turbo-MIMO) systems. We derive a symbol estimator by minimizing the power of the interference plus noise, given a priori probabilities of undetected layer symbols and a posteriori

Jun Won Choi; Andrew C. Singer; Jung Woo Lee; Nam Ik Cho

2010-01-01

378

Quantization noise in single-loop sigma-delta modulation with sinusoidal inputs  

Microsoft Academic Search

An exact nonlinear difference equation is derived and solved for a simple sigma-delta modulator consisting of a discrete-time integrator and a binary quantizer inside a single feedback loop and an arbitrary input signal. It is shown that the system can be represented as an affine operation (discrete-time integration of a biased input) followed by a memoryless nonlinearity. An extension of

ROBERT M. GRAY; W. Chou; P. W. Wong

1989-01-01

379

Six axis force feedback input device  

NASA Technical Reports Server (NTRS)

The present invention is a low friction, low inertia, six-axis force feedback input device comprising an arm with double-jointed, tendon-driven revolute joints, a decoupled tendon-driven wrist, and a base with encoders and motors. The input device functions as a master robot manipulator of a microsurgical teleoperated robot system including a slave robot manipulator coupled to an amplifier chassis, which is coupled to a control chassis, which is coupled to a workstation with a graphical user interface. The amplifier chassis is coupled to the motors of the master robot manipulator and the control chassis is coupled to the encoders of the master robot manipulator. A force feedback can be applied to the input device and can be generated from the slave robot to enable a user to operate the slave robot via the input device without physically viewing the slave robot. Also, the force feedback can be generated from the workstation to represent fictitious forces to constrain the input device's control of the slave robot to be within imaginary predetermined boundaries.

Ohm, Timothy (Inventor)

1998-01-01

380

An exploratory pilot study into the association between microcirculatory parameters derived by MRI-based pharmacokinetic analysis and glucose utilization estimated by PET-CT imaging in head and neck cancer  

Microsoft Academic Search

Objectives:  To examine the feasibility of deriving quantitative microcirculatory parameters and to investigate the relationship between\\u000a vascular and metabolic characteristics of head and neck tumours in vivo, using dynamic contrast-enhanced (DCE) MRI and fluorodeoxyglucose\\u000a (FDG) PET imaging.\\u000a \\u000a \\u000a \\u000a \\u000a Methods:  Twenty-seven patients with primary squamous cell carcinoma (SCCA) underwent DCE-MRI and combined PET\\/CT imaging. DCE-MRI data\\u000a were post-processed by using commercially available software. Transfer

Sotirios Bisdas; Oliver Seitz; Markus Middendorp; Nicole Chambron-Pinho; Theodosios Bisdas; Thomas J. Vogl; Renate Hammerstingl; Ulrike Ernemann; Martin G. Mack

2010-01-01

381

Gradient echo plural contrast imaging--signal model and derived contrasts: T2*, T1, phase, SWI, T1f, FST2*and T2*-SWI.  

PubMed

Gradient Echo Plural Contrast Imaging (GEPCI) is a post processing technique that, based on a widely available multiple gradient echo sequence, allows simultaneous generation of naturally co-registered images with various contrasts: T1 weighted, R2*=1/T2* maps and frequency (f) maps. Herein, we present results demonstrating the capability of GEPCI technique to generate image sets with additional contrast characteristics obtained by combing the information from these three basic contrast maps. Specifically, we report its ability to generate GEPCI-susceptibility weighted images (GEPCI-SWI) with improved SWI contrast that is free of T1 weighting and RF inhomogeneities; GEPCI-SWI-like images with the contrast similar to original SWI; T1f images that offer superior GM/WM matter contrast obtained by combining the GEPCI T1 and frequency map data; Fluid Suppressed T2* (FST2*) images that utilize GEPCI T1 data to suppress CSF signal in T2* maps and provide contrast similar to FLAIR T2 weighted images; and T2*-SWI images that combine SWI contrast with quantitative T2* map and offer advantages of visualizing venous structure with hyperintense T2* lesions (e.g. MS lesions). To analyze GEPCI images we use an improved algorithm for combining data from multi-channel RF coils and a method for unwrapping phase/frequency maps that takes advantage of the information on phase evolution as a function of gradient echo time in GEPCI echo train. PMID:22305993

Luo, Jie; Jagadeesan, Bharathi D; Cross, Anne H; Yablonskiy, Dmitriy A

2012-04-01

382

Gradient Echo Plural Contrast Imaging - signal model and derived contrasts: T2*, T1, Phase, SWI, T1f, FST2*and T2*-SWI  

PubMed Central

Gradient Echo Plural Contrast Imaging (GEPCI) is a post processing technique that, based on a widely available multiple gradient echo sequence, allows simultaneous generation of naturally co-registered images with various contrasts: T1 weighted, R2* = 1/T2* maps and frequency (f) maps. Herein, we present results demonstrating the capability of GEPCI technique to generate image sets with additional contrast characteristics obtained by combing the information from these three basic contrast maps. Specifically, we report its ability to generate GEPCI-susceptibility weighted images (GEPCI-SWI) with improved SWI contrast that is free of T1 weighting and RF inhomogeneities; GEPCI-SWI-like images with the contrast similar to original SWI; T1f images that offer superior GM/WM matter contrast obtained by combining the GEPCI T1 and frequency map data; Fluid Suppressed T2* (FST2*) images that utilize GEPCI T1 data to suppress CSF signal in T2* maps and provide contrast similar to FLAIR T2 weighted images; and T2*-SWI images that combine SWI contrast with quantitative T2* map and offer advantages of visualizing venous structure with hyperintense T2* lesions (e.g. MS lesions). To analyze GEPCI images we use an improved algorithm for combining data from multi-channel RF coils and a method for unwrapping phase/frequency maps that takes advantage of the information on phase evolution as a function of gradient echo time in GEPCI echo train.

Luo, Jie; Jagadeesan, Bharathi D; Cross, Anne H; Yablonskiy, Dmitriy A

2012-01-01

383

Computer Generated Inputs for NMIS Processor Verification  

SciTech Connect

Proper operation of the Nuclear Identification Materials System (NMIS) processor can be verified using computer-generated inputs [BIST (Built-In-Self-Test)] at the digital inputs. Preselected sequences of input pulses to all channels with known correlation functions are compared to the output of the processor. These types of verifications have been utilized in NMIS type correlation processors at the Oak Ridge National Laboratory since 1984. The use of this test confirmed a malfunction in a NMIS processor at the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) in 1998. The NMIS processor boards were returned to the U.S. for repair and subsequently used in NMIS passive and active measurements with Pu at VNIIEF in 1999.

J. A. Mullens; J. E. Breeding; J. A. McEvers; R. W. Wysor; L. G. Chiang; J. R. Lenarduzzi; J. T. Mihalczo; J. K. Mattingly

2001-06-29

384

Study of the Effect and Design Criteria of the Input Filter for Buck Converters With Peak Current-Mode Control Using a Novel System Block Diagram  

Microsoft Academic Search

The effect and design criteria of the input filter for buck converters with peak current-mode (PCM) control are researched using a novel system block diagram. With this diagram, a novel current loop transfer function is proposed to derive the design criteria that apply to designing the input filter. However, the input filter that is added to reduce electromagnetic interference will

Shen-Yaur Chen; Jin-Jia Chen

2008-01-01

385

An input adaptive, pursuit tracking model of the human opertor  

NASA Technical Reports Server (NTRS)

Developed and evaluated is a simple model of the input adaptive behavior of the human operator (HO) in a pursuit tracking task in which the plant controlled consists of a pure gain. If it is assumed that the HO is approximately an optimal predictor using only position and velocity information, then there is a simple method of computing the values of the model parameters in terms of the autocorrelation function of the input signal. Experimental evidence indicates that the ability of the HO to use velocity information decreases with increasing signal velocity indicating that a biased estimator of the velocity weighting should be used. A suitable approximation is derived which has rapid convergence and low variance. The model thus derived is compared to actual subject transfer functions and is found to be in close agreement. In addition to tracking random processes the model can adapt to and track deterministic signals, such as sine waves, up to approximately the frequency at which human operators begin to track precognitively.

Ware, J. R.

1972-01-01

386

Derivatives Page  

NSDL National Science Digital Library

Derivatives are financial securities whose value is derived from another "underlying" financial security. Options, futures, swaps, swaptions, and structured notes are all examples of derivative securities. Derivatives can be used in hedging, protecting against financial risk, or can be used to speculate on the movement of commodity or security prices, interest rates, or the levels of financial indices. The valuation of derivatives makes use of the statistical mathematics of uncertainty. With links to related articles. See also Derivatives Concepts A-Z, glossary of derivatives-related terminology designed to make the other articles in the Financial Pipeline's Derivatives section easier to understand.

2007-03-22

387

Visceral Sensory Inputs to the Endocrine Hypothalamus  

PubMed Central

Interoceptive feedback signals from the body are transmitted to hypothalamic neurons that control pituitary hormone release. This review article describes the organization of central neural pathways that convey ascending visceral sensory signals to endocrine neurons in the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus in rats. A special emphasis is placed on viscerosensory inputs to corticotropin releasing factor (CRF)-containing PVN neurons that drive the hypothalamic-pituitary-adrenal axis, and on inputs to magnocellular PVN and SON neurons that release vasopressin (AVP) or oxytocin (OT) from the posterior pituitary. The postnatal development of these ascending pathways also is considered.

Rinaman, Linda

2007-01-01

388

An update of input instructions to TEMOD  

NASA Technical Reports Server (NTRS)

The theory and operation of a FORTRAN 4 computer code, designated as TEMOD, used to calcuate tubular thermoelectric generator performance is described in WANL-TME-1906. The original version of TEMOD was developed in 1969. A description is given of additions to the mathematical model and an update of the input instructions to the code. Although the basic mathematical model described in WANL-TME-1906 has remained unchanged, a substantial number of input/output options were added to allow completion of module performance parametrics as required in support of the compact thermoelectric converter system technology program.

1973-01-01

389

Input-output linearisation of nonlinear systems with ill-defined relative degree: the ball and beam revisited  

Microsoft Academic Search

We establish that for SISO systems lack of well-defined relative degree is not an obstacle to exact inversion. Sufficient conditions for the existence of exact linearising inputs are derived. Exact tracking solutions of a number of example systems, including the ball and beam system studied by Hauser et al. (1992), are analysed. It is shown that linearising inputs may be:

D. J. Leith; W. E. Leithead

2001-01-01

390

A stochastic multiple-input-multiple-output radio channel model for evaluation of space-time coding algorithms  

Microsoft Academic Search

A simple framework for Monte Carlo simulations of a multiple-input-multiple-output radio channel is proposed. The derived model includes the partial correlation between the paths in the channel, as well as fast fading and time dispersion. The only input parameters required for the model are the shape of the power delay spectrum and the spatial correlation functions at the transmit and

Klaus I. Pedersen; Jorgen Bach Andersen; J. P. Kermoal; Preben Mogensen

2000-01-01

391

Identifying Inputs Toward Production Function Application in Education.  

ERIC Educational Resources Information Center

Production function applications to improve the efficiency of educational programs require identification of inputs and outputs and the establishment of a data bank to provide information on input and output variables. This generalizable input identification model organizes inputs for systems analysis at various levels of inputs and provides a…

Copa, George H.

392

Image enhancement by non-linear extrapolation in frequency space  

NASA Technical Reports Server (NTRS)

An input image is enhanced to include spatial frequency components having frequencies higher than those in an input image. To this end, an edge map is generated from the input image using a high band pass filtering technique. An enhancing map is subsequently generated from the edge map, with the enhanced map having spatial frequencies exceeding an initial maximum spatial frequency of the input image. The enhanced map is generated by applying a non-linear operator to the edge map in a manner which preserves the phase transitions of the edges of the input image. The enhanced map is added to the input image to achieve a resulting image having spatial frequencies greater than those in the input image. Simplicity of computations and ease of implementation allow for image sharpening after enlargement and for real-time applications such as videophones, advanced definition television, zooming, and restoration of old motion pictures.

Anderson, Charles H. (Inventor); Greenspan, Hayit K. (Inventor)

1998-01-01

393

Economic and Ecological Input-Output Model.  

ERIC Educational Resources Information Center

This documentation presents an input-output model which has been modified to include the environmental impact of economic operation. In lieu of market prices for the environmental factors, trade-offs with regional income and employment are estimated for use in regional planning. The program is written in FORTRAN IV with single precision for the…

Blaylock, James E.; Jones, Lonnie L.

394

Anomalous Response Times of Input Synchronizers  

Microsoft Academic Search

This paper deals with an anomalous behavior of input synchronizers which results in the occurrence of random errors in asynchronously interfaced synchronous digital systems. The errors are caused by the undefined response time of a flip-flop as it recovers from its metastable state. To obtain their frequency, the timing diagram of the flip-flops has been analyzed and the probability distribution

Miroslav Pechoucek

1976-01-01

395

"Thumball" Auxiliary Data-Input Device  

NASA Technical Reports Server (NTRS)

Track-ball-type device mounted on joystick and operated by thumb. Thumball designed to enable precise input of data about two different axes to autopilot, avionics computer, or other electronic device without need for operator to remove hands from joystick or other vehicle control levers.

Garner, H. Douglas; Busquets, Anthony M.; Hogge, Thomas W.; Parrish, Russell V.

1988-01-01

396

The Smart Phone: A Ubiquitous Input Device  

Microsoft Academic Search

We show how modern mobile phones (Weiser's tabs) can interact with their environment, especially large situated displays (Weiser's boards). Smart phones' emerging capabilities are fueling a rise in the use of mobile phones as input devices to such resources as situated displays, vending machines, and home appliances. Mobile phones' prevalence gives them great potential to be the default physical interface

Rafael Ballagas; Jan Borchers; Michael Rohs; Jennifer G. Sheridan

2006-01-01

397

Manual and gaze input cascaded (MAGIC) pointing  

Microsoft Academic Search

This work explores a new direction in utilizing eye gaze forcomputer input. Gaze tracking has long been considered as analternative or potentially superior pointing method for computerinput. We believe that many fundamental limitations exist withtraditional gaze pointing. In particular, it is unnatural tooverload a perceptual channel such as vision with a motor controltask. We therefore propose an alternative approach, dubbed

Shumin Zhai; Carlos Morimoto; Steven Ihde

1999-01-01