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1

Improved Imaged-derived Input Function for Study of Human Brain FDG-PET  

E-print Network

Improved Imaged-derived Input Function for Study of Human Brain FDG-PET Hongbin Guo, Rosemary tomography (PET) studies. Two time windows can be recognized in the time activity curve measured from the compartmental model for FDG PET [5]. Index Terms Quantification of FDG PET, Automated Image-derived input

Renaut, Rosemary

2

A multimodal approach to image-derived input functions for brain PET  

Microsoft Academic Search

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

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

2009-01-01

3

Image-Derived Input Function for [ 11C]Flumazenil Kinetic Analysis in Human Brain  

Microsoft Academic Search

PURPOSE: We describe a method for analysis of [11C]flumazenil data using an input curve directly derived from the positron emission tomography (PET) images.PROCEDURE: The shape of the tracer plasma curve was obtained from the product of the intact flumazenil fraction in plasma in six arterial samples and the internal carotid artery time-activity curve (TAC). The resulting curve was calibrated using

Sandra M. Sanabria-Bohórquez; Alex Maes; Patrick Dupont; Guy Bormans; Tjibbe de Groot; Alexandre Coimbra; WaiSi Eng; Tine Laethem; Inge De Lepeleire; Jay Gambale; Jose M. Vega; H. Donald Burns

2003-01-01

4

Image-derived input function for brain PET studies: many challenges and few opportunities  

PubMed Central

Quantitative positron emission tomography (PET) brain studies often require that the input function be measured, typically via arterial cannulation. Image-derived input function (IDIF) is an elegant and attractive noninvasive alternative to arterial sampling. However, IDIF is also a very challenging technique associated with several problems that must be overcome before it can be successfully implemented in clinical practice. As a result, IDIF is rarely used as a tool to reduce invasiveness in patients. The aim of the present review was to identify the methodological problems that hinder widespread use of IDIF in PET brain studies. We conclude that IDIF can be successfully implemented only with a minority of PET tracers. Even in those cases, it only rarely translates into a less-invasive procedure for the patient. Finally, we discuss some possible alternative methods for obtaining less-invasive input function. PMID:21811289

Zanotti-Fregonara, Paolo; Chen, Kewei; Liow, Jeih-San; Fujita, Masahiro; Innis, Robert B

2011-01-01

5

Arterial input function derived from pairwise correlations between PET-image voxels  

PubMed Central

A metabolite corrected arterial input function is a prerequisite for quantification of positron emission tomography (PET) data by compartmental analysis. This quantitative approach is also necessary for radioligands without suitable reference regions in brain. The measurement is laborious and requires cannulation of a peripheral artery, a procedure that can be associated with patient discomfort and potential adverse events. A non invasive procedure for obtaining the arterial input function is thus preferable. In this study, we present a novel method to obtain image-derived input functions (IDIFs). The method is based on calculation of the Pearson correlation coefficient between the time-activity curves of voxel pairs in the PET image to localize voxels displaying blood-like behavior. The method was evaluated using data obtained in human studies with the radioligands [11C]flumazenil and [11C]AZ10419369, and its performance was compared with three previously published methods. The distribution volumes (VT) obtained using IDIFs were compared with those obtained using traditional arterial measurements. Overall, the agreement in VT was good (?3% difference) for input functions obtained using the pairwise correlation approach. This approach performed similarly or even better than the other methods, and could be considered in applied clinical studies. Applications to other radioligands are needed for further verification. PMID:23571279

Schain, Martin; Benjaminsson, Simon; Varnas, Katarina; Forsberg, Anton; Halldin, Christer; Lansner, Anders; Farde, Lars; Varrone, Andrea

2013-01-01

6

Image derived input functions for dynamic High Resolution Research Tomograph PET brain studies.  

PubMed

The High Resolution Research Tomograph (HRRT) is a dedicated human brain positron emission tomography (PET) scanner. The aim of the present study was to validate the use of image derived input functions (IDIF) as an alternative for arterial sampling for HRRT human brain studies. To this end, IDIFs were extracted from 3D ordinary Poisson ordered subsets expectation maximization (OP-OSEM) and reconstruction based partial volume corrected (PVC) OP-OSEM images. IDIFs, either derived directly from regions of interest or further calibrated using manual samples taken during scans, were evaluated for dynamic [(11)C]flumazenil data (n=6). Results obtained with IDIFs were compared with those obtained using blood sampler input functions (BSIF). These comparisons included areas under the curve (AUC) for peak (0-3.3 min) and tail (3.3-55.0 min). In addition, slope, intercept and Pearson's correlation coefficient of tracer kinetic analysis results based on IDIF and BSIF were calculated for each subject. Good peak AUC ratios (0.83+/-0.21) between IDIF and BSIF were found for calibrated IDIFs extracted from OP-OSEM images. This combination of IDIFs and images also provided good slope values (1.07+/-0.11). Improved resolution, as obtained with PVC OP-OSEM, changed AUC ratios to 1.14+/-0.35 and, for tracer kinetic analysis, slopes changed to 0.95+/-0.13. For all reconstructions, non-calibrated IDIFs gave poorer results (>61+/-34% higher slopes) compared with calibrated IDIFs. The results of this study indicate that the use of IDIFs, extracted from OP-OSEM or PVC OP-OSEM images, is feasible for dynamic HRRT data, thereby obviating the need for online arterial sampling. PMID:18707007

Mourik, Jurgen E M; van Velden, Floris H P; Lubberink, Mark; Kloet, Reina W; van Berckel, Bart N M; Lammertsma, Adriaan A; Boellaard, Ronald

2008-12-01

7

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. PMID:20607124

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

2010-01-01

8

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

9

Image-derived input function in PET brain studies: blood-based methods are resistant to motion artifacts  

PubMed Central

Background Image-derived input function (IDIF) from carotid arteries is an elegant alternative to full arterial blood sampling for brain PET studies. However, a recent study using blood-free IDIFs found that this method is particularly vulnerable to patient motion. The present study used both simulated and clinical [11C](R)-rolipram data to assess the robustness of a blood-based IDIF method (a method that is ultimately normalized with blood samples) with regard to motion artifacts. Methods The impact of motion on the accuracy of IDIF was first assessed with an analytical simulation of a high-resolution research tomograph using a numerical phantom of the human brain, equipped with internal carotids. Different degrees of translational (from 1 to 20mm) and rotational (from 1 to 15°) motions were tested. The impact of motion was then tested on the high-resolution research tomograph dynamic scans of three healthy volunteers, reconstructed with and without an online motion correction system. IDIFs and Logan-distribution volume (VT) values derived from simulated and clinical scans with motion were compared with those obtained from the scans with motion correction. Results In the phantom scans, the difference in the area under the curve (AUC) for the carotid time–activity curves was up to 19% for rotations and up to 66% for translations compared with the motionless simulation. However, for the final IDIFs, which were fitted to blood samples, the AUC difference was 11% for rotations and 8% for translations. Logan-VT errors were always less than 10%, except for the maximum translation of 20 mm, in which the error was 18%. Errors in the clinical scans without motion correction appeared to be minor, with differences in AUC and Logan-VT always less than 10% compared with scans with motion correction. Conclusion When a blood-based IDIF method is used for neurological PET studies, the motion of the patient affects IDIF estimation and kinetic modeling only minimally. PMID:22760300

Zanotti-Fregonara, Paolo; Liow, Jeih-San; Comtat, Claude; Zoghbi, Sami S.; Zhang, Yi; Pike, Victor W.; Fujita, Masahiro; Innis, Robert B.

2013-01-01

10

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

11

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

PubMed Central

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 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. Grey and white matter CBF values were 61.4 ± 11.0 and 15.6 ± 3.0 mL/min/100g 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/100g 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. PMID:23442733

Fung, Edward K; Carson, Richard E

2013-01-01

12

Local Binary Patterns Calculated Over Gaussian Derivative Images  

E-print Network

Local Binary Patterns Calculated Over Gaussian Derivative Images Varun Jain James L. Crowley analysis. We combine Gaussian derivatives with Local Binary Patterns to provide a robust and powerful derivatives form the input to the Linear Binary Pattern(LBP) operator instead of the original image

Paris-Sud XI, Université de

13

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

14

Robust image retrieval from noisy inputs using lattice associative memories  

NASA Astrophysics Data System (ADS)

Lattice associative memories also known as morphological associative memories are fully connected feedforward neural networks with no hidden layers, whose computation at each node is carried out with lattice algebra operations. These networks are a relatively recent development in the field of associative memories that has proven to be an alternative way to work with sets of pattern pairs for which the storage and retrieval stages use minimax algebra. Different associative memory models have been proposed to cope with the problem of pattern recall under input degradations, such as occlusions or random noise, where input patterns can be composed of binary or real valued entries. In comparison to these and other artificial neural network memories, lattice algebra based memories display better performance for storage and recall capability; however, the computational techniques devised to achieve that purpose require additional processing or provide partial success when inputs are presented with undetermined noise levels. Robust retrieval capability of an associative memory model is usually expressed by a high percentage of perfect recalls from non-perfect input. The procedure described here uses noise masking defined by simple lattice operations together with appropriate metrics, such as the normalized mean squared error or signal to noise ratio, to boost the recall performance of either the min or max lattice auto-associative memories. Using a single lattice associative memory, illustrative examples are given that demonstrate the enhanced retrieval of correct gray-scale image associations from inputs corrupted with random noise.

Urcid, Gonzalo; Nieves-V., José Angel; García-A., Anmi; Valdiviezo-N., Juan Carlos

2009-02-01

15

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

16

For every movement we perform the brain receives inputs from the muscles, skin, tendons and joints -and from these inputs the brain derives a sense of oneself or  

E-print Network

For every movement we perform the brain receives inputs from the muscles, skin, tendons and joints - and from these inputs the brain derives a sense of oneself or 'proprioception'. Proprioception is processed for higher brain function - the cerebral cortex - governs our skilful actions. Notably, the motor cortex

Govindarajan, Ramaswamy

17

Classification of multispectral images using BP-neural network classifier-input codings assessment  

Microsoft Academic Search

The research effort reported in this paper focused on the evaluation of different input codings influencing the performance of a backpropagation (BP) neural network for the classification of multispectral images. The assessments of the input codings are based on the performances of a network classifier using five different input coding schemes, namely normalization, temperature, coarse, binary coded decimal and Gray

C. C. Chong; J. C. Jia; D. P. Mital

1994-01-01

18

Limits to Image Reconstruction from Restricted Angular Input.  

National Technical Information Service (NTIS)

Distortion in an object due to the unavailability of some Fourier components in a cone-shaped region is analyzed. The results throw light on the factors that limit the accuracy in reconstructing objects from limited-angle input in practice. It is also sho...

K. C. Tam, V. Perez-Mendez

1980-01-01

19

Assessment of neural network input codings for classification of multispectral images  

Microsoft Academic Search

The research effort reported in this paper focuses on the evaluation of different input codings influencing the performance of a back-propagation neural network for classification of remotely sensed images. The clustering capability, which can be visualized through the Euclidean distance graph, is introduced as a tool to predict the credibility of the input coding. An investigation was also conducted to

Jiancheng Jia; Cheechung Chong

1996-01-01

20

Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen  

NASA Astrophysics Data System (ADS)

The Southern Ocean is known as the largest High-Nutrient, Low-Chlorophyll (HNLC) region of the global ocean due to iron limitation. However, a large phytoplankton bloom develops annually downstream of the Kerguelen Islands, which is sustained partly by iron released from the sediments deposited onto the margins. In the framework of the KEOPS-2 project, we used radium isotopes (224Ra, T1/2 = 3.66 d; 223Ra, T1/2 = 11.4 d; 228Ra, T1/2 = 5.75 yr) to provide information on the origin of iron fertilization and on the timescales of the transfer of sediment-derived inputs (including iron and other micronutrients) towards offshore waters. Significant 223Ra and 223Ra activities were found in the near vicinity of the Kerguelen Islands, in agreement with the short half-lives of these isotopes. Significant 224Ra and 223Ra activities were also detected up to 200 km downstream of the islands and more unexpectedly in offshore waters south of the Polar Front. These observations thus clearly indicate (i) that the sediment-derived inputs are rapidly transferred towards offshore waters (on timescales in the order of several days up to several weeks) and (ii) that the Polar Front is not a physical barrier for the chemical elements released from the sediments of Kerguelen Plateau. The Ra dataset suggests that iron and other micronutrients released by the shallow sediments of the Kerguelen margins may contribute to fuel the phytoplankton bloom downstream of the islands, despite the presence of the Polar Front. However, the heterogeneous distribution of the 224Ra and 223Ra activities in surface waters suggests that this supply across the front is not a continuous process, but rather a process that is highly variable in space and time.

Sanial, V.; van Beek, P.; Lansard, B.; Souhaut, M.; Kestenare, E.; d'Ovidio, F.; Zhou, M.; Blain, S.

2014-09-01

21

Assessment of neural network input codings for classification of multispectral images  

NASA Astrophysics Data System (ADS)

The research effort reported in this paper focuses on the evaluation of different input codings influencing the performance of a back-propagation neural network for classification of remotely sensed images. The clustering capability, which can be visualized through the Euclidean distance graph, is introduced as a tool to predict the credibility of the input coding. An investigation was also conducted to study the use of weight function to improve the clustering capability of the binary-coded-decimal input coding, a widely used coding approach in remote sensing area. Results obtained indicate that the classification performance of the neural network classifier is closely related to the clustering capability of the input codings. In order to fully exploit the generalization property of neural network, the clustering property of the classes must be maintained during the input coding process.

Jia, Jiancheng; Chong, Cheechung

1996-12-01

22

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

23

Shelf-derived iron inputs drive biological productivity in the southern Drake Passage  

NASA Astrophysics Data System (ADS)

In the Southern Ocean near the Antarctic Peninsula, Antarctic Circumpolar Current (ACC) fronts interact with shelf waters facilitating lateral transport of shelf-derived components such as iron into high-nutrient offshore regions. To trace these shelf-derived components and estimate lateral mixing rates of shelf water, we used naturally occurring radium isotopes. Short-lived radium isotopes were used to quantify the rates of shelf water entrainment while Fe/228Ra ratios were used to calculate the Fe flux. In the summer of 2006 we found rapid mixing and significant lateral iron export, namely, a dissolved iron flux of 1.1 × 105 mol d-1 and total acid leachable iron flux of 1.1 × 106 mol d-1 all of which is transported in the mixed layer from the shelf region offshore. This dissolved iron flux is significant, especially considering that the bloom observed in the offshore region (0.5-2 mg chl a m-3) had an iron demand of 1.1 to 4 × 105 mol Fe. Net vertical export fluxes of particulate Fe derived from 234Th/238U disequilibrium and Fe/234Th ratios accounted for only about 25% of the dissolved iron flux. On the other hand, vertical upward mixing of iron rich deeper waters provided only 7% of the lateral dissolved iron flux. We found that similarly to other studies in iron-fertilized regions of the Southern Ocean, lateral fluxes overwhelm vertical inputs and vertical export from the water column and support significant phytoplankton blooms in the offshore regions of the Drake Passage.

Dulaiova, H.; Ardelan, M. V.; Henderson, P. B.; Charette, M. A.

2009-12-01

24

Multiple-input ghost imaging via sparsity constraints with thermal light  

NASA Astrophysics Data System (ADS)

Single-pixel detection is one of the advantages of ghost imaging via sparsity constraints (GISC), but numerous modulations from the source are usually required to obtain an image with a good signal-to-noise ratio. When the spatial information at the detection plane is taken into consideration and recorded by sparse-array single-pixel detectors, we experimentally demonstrate that multiple-input ghost imaging via sparsity constraints (MI-GISC) with thermal light can further reduce the source’s modulations compared with GISC. Factors affecting the imaging quality of MI-GISC with thermal light are also discussed.

Bo, Zunwang; Gong, Wenlin; Li, Enrong; Han, Shensheng

2014-10-01

25

Derived flood frequency analysis using different precipitation input data - a comparison  

NASA Astrophysics Data System (ADS)

For planning of hydraulic structures design floods with different recurrence intervals are required. For monitored river cross sections these values are usually obtained using flood frequency analysis based on long time series of observed discharge. If such observations are missing or if effects of new flood protection measures or changes in natural conditions are to be evaluated derived flood frequency analysis based on continuous rainfall-runoff modelling is a recommended alternative. The objective of this contribution is the comparison of rainfall-runoff modelling for the estimation of floods using three different rainfall inputs on an hourly time step. First design storms are used with event based hydrological modelling. Then two different types of synthetic precipitation loads are applied with continuous hydrological modelling. These are disaggregated daily precipitation data based on a multiplicative random cascade model and stochastic precipitation generated using a space-time alternating renewal model. The specific focus of this study is to investigate strategies for optimal parameter estimation and application of a rainfall-runoff model for derived flood frequency analysis considering different precipitation data. For hydrologic modelling the conceptual semi distributed model HEC-HMS is used. The study areas are some mesoscale catchments within the Bode river basin in northern Germany. For parameter estimation and application of the hydrological model the following three strategies are investigated: a) calibration of the model on observed single events b) calibration of the model on observed discharge time series, each using observed precipitation data as model input. In the third strategy c) calibration of the model on fitted probability distributions of observed annual maximum discharge series is carried out using synthetic precipitation data. For application of the model to estimate the design floods precipitation data and parameter sets are combined as follows. For single events design storms and parameter sets a) and b) are used, and for continuous simulation synthetic precipitation data and parameter sets b) and c) are applied. Then the peak flows of the simulated runoff time series are statistically analysed. Finally, the estimated flood quantiles resulting from the different precipitation loads and calibration strategies are compared with observed flood statistics paying special attention to the uncertainty. The results show that the spread of the uncertainty bands can be reduced considerably if synthetic rainfall is used directly for calibration of the hydrological model based on probability distributions of observed annual maximum flows.

Radtke, Imke; Haberlandt, Uwe

2010-05-01

26

Multifocus fusion is the process of fusing focal information from a set of input images into one all-in-  

E-print Network

Abstract Multifocus fusion is the process of fusing focal information from a set of input images into one all-in- focus image. Here, a versatile multifocus fusion algorithm is presented for application-independent fusion. A focally connected region is a region or a set of regions in an input image that falls under

Koschan, Andreas

27

Quantitative phase reconstruction from input-output intensities using a shift-invariant linear imaging system  

SciTech Connect

We formulate an iteration scheme for quantitative two-dimensional phase retrieval of complex scalar wave fields from input-output intensity profiles using a coherent rotationally symmetric shift-invariant linear optical imaging system. This method is a generalization of our previous method for quantitative single-image pure phase reconstruction using an imperfect shift-invariant linear imaging system. The method is somewhat analogous to the Gerchberg-Saxton iterative phase-retrieval algorithm, but typically converges much more rapidly. We have demonstrated the efficacy of the method using simulated data in the presence of noise.

Yu, Rotha P.; Paganin, David M. [School of Physics, Monash University, Victoria 3800 (Australia)

2009-05-15

28

Regional biomass and leaf-area estimates derived from satellite imagery as inputs to spatial trace-gas flux models for arctic tundra  

SciTech Connect

Reflectance spectra, leaf area index (LAI), and live biomass measurements were collected for 60 plots near Toolik Lake and Imnavait Creek, Alaska during July and August, 1993. Normalized difference vegetation indices (NDVI) were calculated from the reflectance spectra. NDVI was found to be highly correlated to both LAI and biomass. These relationships have been seen in temperate ecosystems, but have never been tested in Arctic tundra previous to this study. In addition, a clear relationship is seen between NDVI values and pH and moisture. Acidic plots have much higher NDVI values than non-acidic plots, while moist plots have high NDVI values relative to dry and wet plots. The average field NDVI measurements for major physiognomic categories were compared to average NDVI values for the same categories derived from a SPOT multispectral satellite image of the area. These values were also found to be highly correlated. However, field NDVI values were consistently about 40% higher than SPOT NDVI values. Possible explanations for this consistent trend include effects of low sun angle in the Arctic in combination with relatively high view angle of the SPOT sensor. Using the regression equations for the above relationships, biomass and LAI images were calculated from the SPOT image. The resulting images show expected trends in the LAI and biomass across the landscape. The image of biomass will be used as an input to a spatial model of methane emissions for the Alaskan Arctic. Another key input variable to the methane model will be soil moisture. Alternative image processing methods and/or radar images will be used to derive this important variable.

Shippert, M.M.; Walker, D.A.; Auerbach, N.A.; Lewis, B.E. (Univ. of Colorado, Boulder, CO (United States))

1994-06-01

29

Deriving and matching image fingerprint sequences for mobile robot localization  

E-print Network

Deriving and matching image fingerprint sequences for mobile robot localization Pierre Lamon1 identifiers, called fingerprint sequences, for visually distinct locations by recovering statistically significant features in panoramic color images. Fingerprint sequences are expressive enough for mobile robot

Nourbakhsh, Illah

30

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

31

Design method of input phase mask to improve light use efficiency and reconstructed image quality for holographic memory.  

PubMed

A design method of an input phase mask for holographic memory is proposed. In the method, a modification of a design procedure and another restraint condition are applied to our conventional design method. The light use efficiency and the quality of a reconstructed image are improved. The performance of an input phase mask designed by the method is confirmed by numerical simulations. Finally, a suitable design condition of an input phase mask is determined from simulation results. PMID:25089971

Saita, Yusuke; Nomura, Takanori

2014-07-01

32

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. PMID:20381094

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

2010-01-01

33

Spatially multiplexed multi-input-multi-output optical imaging system in a turbid, turbulent atmosphere.  

PubMed

Active optical imaging is preferred over radio frequency counterparts due to its higher resolution, faster area search rate, and relatively easier learning and interpretation of the image by a human observer. However, in imaging through atmosphere, one should consider dispersive effects of multiple scatterings and turbulence-induced wave perturbations, which give rise to intensity fluctuations and wavefront distortions. All these phenomena broaden and distort the spatial impulse response known as the point spread function (PSF). In this paper, a spatially multiplexed multi-input-multi-output imaging system design, inspired by multispot diffuse indoor communications configuration first introduced by Yun and Kavehrad [IEEE International Conference Selected Topics in Wireless Communications (IEEE, 1992), pp 262-265], is presented. At the transmitter, a computer-generated holographic beam splitter is used to generate arrays of beamlets, providing a faster area search rate and a uniformly distributed illumination over the entire target area. Then, at the receiver, an array of photodetectors is used to collect the reflected rays. While a Monte Carlo ray-tracing algorithm developed at Pennsylvania State University, Center for Information and Communications Research (CICTR), is used to model imaging in multiple-scattering turbid media, phase screens are employed to simulate turbulence-induced wavefront distortions. Hence, a comprehensive framework is exploited that takes into account possible sources of degradation. Using this framework, system performance is analyzed under different meteorological conditions. Restoration techniques such as adaptive-optics corrections, blind deconvolution, and time gating are used to improve the contrast and enhance the sharpness and resolution of the images. PMID:20300147

Hajjarian, Zeinab; Kavehrad, Mohsen; Fadlullah, Jarir

2010-03-20

34

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

35

A GOES imager-derived microburst product  

E-print Network

A new multispectral Geostationary Operational Environmental Satellite (GOES) imager product has been developed to assess downburst potential over the western United States employing brightness temperature differences (BTD) between band 3 (upper level water vapor), band 4 (longwave infrared window), and split window band 5. Band 3 is intended to indicate mid to upper-level moisture content and advection while band 5 indicates low-level moisture content. Large BTDs between bands 3 and 5 imply a large relative humidity gradient between the mid-troposphere and the surface, a condition favorable for strong convective downdraft generation due to evaporational cooling of precipitation in the deep sub-cloud layer. In addition, small BTDs between bands 4 and 5 indicate a relatively dry surface layer with solar heating in progress. This paper will outline the development of the GOES-West imager microburst product and present case studies that feature example images, outline potential operational use and assess performa...

Pryor, Kenneth L

2008-01-01

36

Imaging derivative spectroscopy for vegetation dysfunction assessments  

Microsoft Academic Search

The practical application of current airborne and future satellite or space station based high spectral resolution (hyperspectral) imagery to vegetative canopies (sparse or dense) and resulting derived bio-physical variables will depend upon our ability to rapidly apply scientifically based algorithms. Key to these rapid assessments is the selection of the best or optimal channels or bands for detection of plant

Charles R. Bostater

1998-01-01

37

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

38

An activity-subspace approach for estimating the integrated input function and relative distribution volume in PET parametric imaging.  

PubMed

Dynamic positron emission tomography (PET) imaging technique enables the measurement of neuroreceptor distributions corresponding to anatomic structures, and thus, allows image-wide quantification of physiological and biochemical parameters. Accurate quantification of the concentration of neuroreceptor has been the objective of many research efforts. Compartment modeling is the most widely used approach for receptor binding studies. However, current compartment-model-based methods often either require intrusive collection of accurate arterial blood measurements as the input function, or assume the existence of a reference region. To obviate the need for the input function or a reference region, in this paper, we propose to estimate the input function. We propose a novel concept of activity subspace, and estimate the input function by the analysis of the intersection of the activity subspaces. Then, the input function and the distribution volume (DV) parameter are refined and estimated iteratively. Thus, the underlying parametric image of the total DV is obtained. The proposed method is compared with a blind estimation method, iterative quadratic maximum-likelihood (IQML) via simulation, and the proposed method outperforms IQML. The proposed method is also evaluated in a brain PET dataset. PMID:19129021

Qiu, Peng; Wang, Z Jane; Liu, K J Ray; Szabo, Zsolt

2009-01-01

39

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

40

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. PMID:20952342

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

2011-01-01

41

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. PMID:24420443

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

2014-01-01

42

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

43

Image-based derivation of aerosol optical depth to correct the atmospheric effect for satellite image  

Microsoft Academic Search

An image-based atmospheric correction model for a satellite image is proposed. By assuming Junge size distributed aerosol in the atmosphere and feeding back the new Junge parameter, not only the aerosol optical depth but also the Junge parameter, single scattering albedo and phase function can be iteratively derived and converged from digital counts of dense-dark vegetation (DDV) in the green

C. H. Liu; A. J. Chen; G. R. Liu

1995-01-01

44

A neural network for unsupervised categorization of multivalued input patterns: an application to satellite image clustering  

Microsoft Academic Search

Presents an implementation of an artificial neural network (ANN) which performs unsupervised detection of recognition categories from arbitrary sequences of multivalued input patterns. The proposed ANN is called Simplified Adaptive Resonance Theory Neural Network (SARTNN). First, an Improved Adaptive Resonance Theory 1 (IART1)-based neural network for binary pattern analysis is discussed and a Simplified ART1 (SART1) model is proposed. Second,

Andrea Baraldi; Flavio Parmiggiani

1995-01-01

45

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

46

On the input-output stability of time-varying nonlinear feedback systems Part one: Conditions derived using concepts of loop gain, conicity, and positivity  

Microsoft Academic Search

The object of this paper is to outline a stability theory for input-output problems using functional methods. More particularly, the aim is to derive open loop conditions for the boundedness and continuity of feedback systems, without, at the beginning, placing restrictions on linearity or time invariance. It will be recalled that, in the special case of a linear time invariant

G. Zames

1966-01-01

47

Derivative encoding for parallel magnetic resonance imaging Molecular Imaging Branch, National Institute of Mental Health Intramural Research Program, NIH,  

E-print Network

Derivative encoding for parallel magnetic resonance imaging a) Jun Shenb) Molecular Imaging Branch September 2011) Purpose: To introduce a linear shift-invariant relationship between the partial derivatives- tives can be used for image unwrapping. Methods: Fourier transform of k space derivatives contains

Shen, Jun

48

Biologically derived companding algorithm for high dynamic range mammography images.  

PubMed

The screening mammography is currently the best procedure available for early detection of the breast cancer. The acquired mammograms are high dynamic range (HDR) images having a 12 bit grayscale resolution. When viewed by a radiologist, a single image must be examined several times, each time focusing on a different intensity range. We have developed a biologically derived mammography companding (BDMC) algorithm for compression, expansion, and enhancement of mammograms, in a fully automatic way. The BDMC is comprised of two main processing stages: 1) preliminary processing operations which include standardization of the intensity range and expansion of the intensities which belong to the low intensity range. 2) Adaptively companding the HDR range by integrating multiscale contrast measures. The algorithm's performance has been preliminarily clinically tested on dozens of mammograms in collaboration with experienced radiologists. It appears that the suggested method succeeds in presenting all of the clinical information, including all the abnormalities, in a single low dynamic range companded image. This companded and enhanced image is not degraded more than the HDR image and can be analyzed without the need for professional workstation and its specific enhancement software. PMID:23508248

Kanelovitch, Leon; Itzchak, Yaakov; Rundstein, Arie; Sklair, Miri; Spitzer, Hedva

2013-08-01

49

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. PMID:24198370

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

2013-01-01

50

Imaging synaptically mediated responses produced by brainstem inputs onto identified spinal neurons in the neonatal mouse.  

PubMed

Descending inputs to spinal cord neurons in mammals have previously been characterized functionally using microelectrode recording of single neurons, a technique with high spatial and temporal resolution but low yield. Consequently our knowledge about the functional connections between the brain and the spinal cord has been accumulating at a very low pace. Here we describe a high throughput optical recording approach in an ex vivo brainstem-spinal cord preparation of the neonatal mouse that permits screening many spinal neurons simultaneously for synaptic inputs from descending axons. The fluorescent calcium indicator calcium green dextran amine was loaded retrogradely into specific spinal neuron populations, including motoneurons (MNs) of the medial and lateral motor columns and two populations of interneurons with descending axons (dINs) in the ventral funiculus. Focal electrical stimulation of brainstem neuron populations with descending axons generated synaptic responses revealed by transient increases in intracellular calcium concentration in all four populations of spinal neurons. The resultant fluorescence signals could be readily visualized in individual MNs directly through the ventral white matter. In the more deeply located dINs, responses could be readily visualized in individual neurons from the surface of an oblique cut through the spinal cord. The rapid optical investigation of functional connections between brainstem descending neurons and various populations of spinal neurons in the living mammalian preparation should help uncover some of the key features of supraspinal sensory and motor control and provide a valuable tool for examining the re-innervation of spinal neurons by descending axons after spinal cord regeneration. PMID:19427523

Szokol, Karolina; Perreault, Marie-Claude

2009-05-30

51

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

52

Generating an image from an ambiguous visual input: an electroencephalographic (EEG) investigation.  

PubMed

Fourteen right-handed males were shown slides of common objects (e.g., wristwatch), familiar situations (e.g., two people shaking hands), and inkblots from a popular projective test (Holtzman, 1986) and then asked to name the object, assess the situation, or describe the most salient image emerging from the inkblot. Alpha power suppression was monitored over the left and right frontal, temporal, parietal, and occipital lobes to determine the brain circuitry responsible for the processing of each type of stimulus. When processing common objects and familiar situations there was bilateral activation of the parietal and occipital lobes; when processing inkblots, bilateral activation of the parietal and occipital lobes was again obtained, but complemented by selective activation of the right frontal lobe. The later suggests that anterior regions of the right cerebral hemisphere contribute to the generation of dynamic images like those evoked by visually ambiguous inkblots. PMID:12727183

Gill, Harwant S; O'Boyle, Michael W

2003-04-01

53

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. PMID:24062670

Henderson, Luke A.; Macefield, Vaughan G.

2013-01-01

54

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

55

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

56

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

57

Variational Methods with HigherOrder Derivatives in Image Processing  

E-print Network

of an optical flow field (middle), matrix-valued image of a DT-MRI slice (right). to a symmetric positive of gray­ value images and matrix fields. Vector-valued images are for example col- ored images or optical for the simultaneous esti- mation and decomposition of optical flows [47]. Matrix-valued data have gained significant

Steidl, Gabriele

58

Classification and Visualization Based on Derived Image Features: Application to Genetic Syndromes  

PubMed Central

Data transformations prior to analysis may be beneficial in classification tasks. In this article we investigate a set of such transformations on 2D graph-data derived from facial images and their effect on classification accuracy in a high-dimensional setting. These transformations are low-variance in the sense that each involves only a fixed small number of input features. We show that classification accuracy can be improved when penalized regression techniques are employed, as compared to a principal component analysis (PCA) pre-processing step. In our data example classification accuracy improves from 47% to 62% when switching from PCA to penalized regression. A second goal is to visualize the resulting classifiers. We develop importance plots highlighting the influence of coordinates in the original 2D space. Features used for classification are mapped to coordinates in the original images and combined into an importance measure for each pixel. These plots assist in assessing plausibility of classifiers, interpretation of classifiers, and determination of the relative importance of different features. PMID:25405460

Balliu, Brunilda; Würtz, Rolf P.; Horsthemke, Bernhard; Wieczorek, Dagmar; Böhringer, Stefan

2014-01-01

59

Digital Image Processing "Cookbook": A method to derive bathymetric data from high spatial resolution multi-  

E-print Network

Digital Image Processing "Cookbook": A method to derive bathymetric data from high spatial imagery. It records image processing steps of the second run through an image specific methodology) Tutuila IKONOS Satellite Image (purchased from GeoEye, Inc.) Collection date/time: March 3, 2002/21:38 GMT

Wright, Dawn Jeannine

60

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

61

Linear alkylbenzenes as tracers of sewage-sludge-derived inputs of organic matter, PCBs, and PAHs to sediments at the 106-mile deep water disposal site  

USGS Publications Warehouse

Linear alkylbenzenes (LABs) are sensitive source-specific tracers of sewage inputs to the marine environment. Because they are highly particle reactive and nonspecifically sorbed to organic matter, LABs are potential tracers of the transport of both sludge-derived organic matter and other low solubility hydrophobic contaminants (e.g., PCBs and PAHs); sediment trap studies at the 106-Mile Site have shown LABs to be valuable in testing models of sludge deposition to the sea floor. In this study we report on the distributions of LABs, PCBs, PAHs, and Ag in surface sediments collected within a month of the complete cessation of dumping (July, 1992) in the vicinity of the dump site. Total LAB concentrations were lower than those measured by Takada and coworkers in samples from nearby sites collected in 1989. LABs from both studies appear to be significantly depleted (6 to 25-fold) in surface sediments relative to excess Ag (another sludge tracer) when compared to sewage sludge and sediment trap compositions. Comparison of LAB sediment inventories to model predictions of sludge particle fluxes supports the contention that LABs have been lost from the bed. The use of LABs to examine the short-or long-term fate of sludge derived materials in deep-sea sediments should be questioned. The causes of this LAB depletion are unclear at this point, and we discuss several hypotheses. The concentrations of total PCBs and PAHs are both correlated with sludge tracers, suggesting that there may be a measurable contribution of sludge-derived inputs on top of other nonpoint sources of these contaminant classes. This possibility is consistent with the composition of these contaminants determined in recent and historical analyses of sewage sludge.

Lamoureux, E.M.; Brownawell, B.J.; Bothner, M.H.

1996-01-01

62

ASAR WSS PRODUCT VERIFICATION USING DERIVED IMAGE MOSAICS  

Microsoft Academic Search

A program has been written to create image mosaics from ASA_WSS_1P ASAR-WSS level-1 products, providing an overview of the imaged area. The ability to generate WSS mosaics facilitates the study of several WSS product features. This study focuses on their radiometric and geometric characteristics. The incidence angle variation of 16 to 43 degrees across beams SS1 through SS5 creates large

Adrian Schubert; Betlem Rosich; Erich Meier

2007-01-01

63

Application research on enhancing near-infrared micro-imaging quality by 2nd derivative  

NASA Astrophysics Data System (ADS)

Near-infrared micro-imaging will not only provide the sample's spatial distribution information, but also the spectroscopic information of each pixel. In this thesis, it took the artificial sample of wheat flour and formaldehyde sodium sulfoxylate distribution given for example to research the data processing method for enhancing the quality of near-infrared micro-imaging. Near-infrared spectroscopic feature of wheat flour and formaldehyde sodium sulfoxylate being studied on, compare correlation imaging and 2nd derivative imaging were applied in the imaging processing of the near-infrared micro-image of the artificial sample. Furthermore, the two methods were combined, i.e. 2nd derivative compare correlation imaging was acquired. The result indicated that the difference of the correlation coefficients between the two substances, i.e. wheat flour and formaldehyde sodium sulfoxylate, and the reference spectrum has been increased from 0.001 in compare correlation image to 0.796 in 2nd derivative compare correlation image respectively, which enhances the imaging quality efficiently. This study will, to some extent, be of important reference significance to near-infrared micro-imaging method research of agricultural products and foods.

Wang, Dong; Ma, Zhi-hong; Zhao, Liu; Wang, Bei-hong; Han, Ping; Pan, Li-gang; Wang, Ji-hua

2013-08-01

64

Tropical Cyclone Parameters Derived from Synthetic Aperture Radar (SAR) Images  

Microsoft Academic Search

Ocean waves play an important role in the dynamics of extreme events like hurricanes or typhoons by conditioning the air\\/sea fluxes of momentum, heat and moisture. In this study a data set of ENVISAT ASAR Scan SAR images (400 times 400 km coverage) are used to observe the structure of tropical cyclones and typhoons at the sea surface. The following

A. Reppucci; S. Lehner; J. Schulz-Stellenfleth

2006-01-01

65

Synthesis of an (iodovinyl)misonidazole derivative for hypoxia imaging.  

PubMed

Nitroimidazoles undergo a bioreduction in viable hypoxic tissue, resulting in trapping within these tissues, as demonstrated by misonidazole. A radioiodinated analogue of misonidazole (IVM, (E)-5-(2-Nitroimidazolyl)-4-hydroxy-1-iodopent-1-ene, 3) has been synthesized by halodestannylation, for evaluation as an imaging agent for hypoxia. A key step in the synthetic sequence involves the use of the Lewis acid BF3.Et2O to promote the nucleophilic ring opening of glycidyl tosylate with (E)-1-lithio-2-(tributylstannyl)ethylene. Direct comparison of IVM versus F-MISO (2) another misonidazole type hypoxic cell marker, in several in vitro cell culture studies, indicates that IVM behaves in analogous fashion to F-MISO and has promise as a hypoxia imaging agent for SPECT. PMID:2066990

Biskupiak, J E; Grierson, J R; Rasey, J S; Martin, G V; Krohn, K A

1991-07-01

66

A Fractional Derivative Approach for Robust Segmentation of Blood Vessels in Digital Fundus Retinal Images  

Microsoft Academic Search

Segmentation of Blood vessels is of key importance in the diagnosis of retinal images and early detection of diabetic retinopathy. In this paper, we propose a novel approach for segmentation of blood vessels in digital fundus retinal images using a fractional derivative-based edge operator. We have tested our algorithm on the standard DRIVE database. The results show significant improvement in

G. VijayaSaradhi; S. Balasubramanian; V. Chandrasekaran

2008-01-01

67

Saliency of color image derivatives: a comparison between computational models and human  

E-print Network

task of salient object detection in real-world images. The psychophysical experiment demonstrates detection confirm that an early fusion of color and contrast provide accurate performance to compute visualSaliency of color image derivatives: a comparison between computational models and human perception

Gevers, Theo

68

High resolution VESTA LAMO atlas derived from Dawn FC images.  

NASA Astrophysics Data System (ADS)

Introduction: NASA's Dawn spacecraft entered orbit of the inner main belt asteroid 4 Vesta on July 16, 2011, and spent about one year in orbit to characterize the geology, elemental and mineralogical composition, topography, shape, and internal structure of Vesta before it departed to asteroid 1 Ceres in late 2012. One of the major goals of the mission was a global mapping of Vesta. Data: The DAWN mission was mapping Vesta from three different orbit heights during Survey orbit (3100 km altitude), HAMO (High Altitude Mapping Orbit, 700 km altitude), and LAMO (Low Altitude Mapping Orbit, 210 km altitude) [1]. The Dawn mission is equipped with a framing camera (FC) [2] which was the prime instrument during the LAMO phase. DAWN orbited Vesta during LAMO in 21 cycles between December 2011 and end of April 2012. The framing camera took about 10,000 clear filter images with a resolution of about 20 m/pixel during these cycles. The images were taken with different viewing angles and different illumination conditions. We selected about 8,000 images for the global coverage of Vesta. Data Processing: The first step of the processing chain is to ortho rectify the images to the proper scale and map projection type. This process requires detailed high-resolution information of the local topography of Vesta. The global topgraphy was calculated during the stereo processing of the HAMO images [3] and was used here. The shape model was used for the calculation of the ray intersection points while the map projection itself was done onto a sphere with a mean radius of 255 km. The next step was the mosaicking of all images to one global mosaic of Vesta, the so called basemap. Vesta map tiles: The Vesta atlas was produced in a scale of 1:200,000 and consists of 30 tiles that conform to the quadrangle scheme proposed by Greeley and Batson [4] and is used for example for mapping Mars in a scale of 1:5,000,000. A map scale of 1:200,000 guarantees a mapping at the highest available DAWN resolution in LAMO and results in an acceptable printing scale for the hardcopy map of 10 pixel/mm. The individual tiles were separately mosaicked and reprojected. Nomenclature: The DAWN team proposed to the International Astronomical Union (IAU) to use the names of vestal virgins and famous Roman women as names for the craters and to use names of places and festivals associated with vestal virgins for other feature names. This proposal was accepted by the IAU and the team could propose 50 names for geological features to the IAU which were also approved [5]. These feature names were applied to the map tiles. The entire Vesta atlas consisting of 30 map tiles will become available to the public through the Planetary Photojournal and the PDS. References: [1] Russell, C.T. and Raymond, C.A., Space Sci. Review, 163, DOI 10.1007/s11214-011-9836-2; [2] Sierks, et al., 2011, Space Sci. Rev., 163, DOI 10.1007/s11214-011-9745-4; [3] Preusker, F. et al., this session; [4] Greeley, R. and Batson, G., 1990, Planetary Mapping, Cambridge University Press; [5] http://planetarynames.wr.usgs.gov/Page/VESTA/target

Roatsch, Thomas; Kersten, Elke; Matz, Klaus-Dieter; Preusker, Frank; Scholten, Frank; Jaumann, Ralf; Raymond, Carol A.; Russell, Cris T.

2013-04-01

69

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 PMID:22190657

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

2012-01-01

70

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 North Atlantic hurricane seasons, NOAA/NESS and NASA/GSFC conducted a cooperative program to determine the best resolution and frequency now available from satellite images for deriving winds to study and forecast tropical cyclones. High spatial and temporal resolution satellite imagery made it feasible to provide a large number of lower and upper tropospheric winds which can be obtained by tracking clouds within 650 km of tropical cyclone centers. Up to 10 (5) times as many low-level winds were derived from images spaced at 3 or 7.5 min intervals as from those at 30 min (15 min) intervals. Rapid-scan full-resolution IR and visible images minimized the 'erroneous' winds derived by tracking cloud elements that propagate by growing on one side and dissipating on the other and by tracking repetitive patterns that provided ambiguous indications of direction of movement.

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

1979-01-01

71

Three very high resolution optical images for land use mapping of a suburban catchment: input to distributed hydrological models  

NASA Astrophysics Data System (ADS)

Keywords : land cover mapping, very high resolution, remote sensing processing techniques, object oriented approach, distributed hydrological model, peri-urban area Urbanization and other modifications of land use affect the hydrological cycle of suburban catchments. In order to quantify these impacts, the AVuPUR project (Assessing the Vulnerability of Peri-Urban Rivers) is currently developing a distributed hydrological model that includes anthropogenic features. The case study is the Yzeron catchment (150 km²), located close to Lyon city, France. This catchment experiences a growing of urbanization and a modification of traditional land use since the middle of the 20th century, resulting in an increase of flooding, water pollution and river banks erosion. This contribution discusses the potentials of automated data processing techniques on three different VHR images, in order to produce appropriate and detailed land cover data for the models. Of particular interest is the identification of impermeable surfaces (buildings, roads, and parking places) and permeable surfaces (forest areas, agricultural fields, gardens, trees…) within the catchment, because their infiltration capacity and their impact on runoff generation are different. Three aerial and spatial images were acquired: (1) BD Ortho IGN aerial images, 0.50 m resolution, visible bands, may 5th 2008; (2) QuickBird satellite image, 2.44 m resolution, visible and near-infrared bands, august 29th 2008; (3) Spot satellite image, 2.50 m resolution, visible and near-infrared bands, September 22nd 2008. From these images, we developed three image processing methods: (1) a pixel-based method associated to a segmentation using Matlab®, (2) a pixel-based method using ENVI®, (3) an object-based classification using Definiens®. We extracted six land cover types from the BD Ortho IGN (visible bands) and height classes from the satellite images (visible and near infrared bands). The three classified images are resampled in the same low resolution of 2.5 m and compared in order to evaluate the accuracy of different image processing methods and to determine for each cover type, the more appropriate image and/or method. This comparison provides hydrologists with a synthetic land cover map. Four parameters affect the accuracy of land cover mapping: firstly the addition of the NIR band improves vegetation classification such as the distinction between coniferous forest and broad-leaved forest. Moreover the intensity of chlorophyllian activity allows us to characterize the use of agricultural fields. Secondly, the images were taken at three dates in the agricultural calendar. This multi-date data allows the discrimination between permanently vegetalized pastures, and temporarily bare crops, a useful information for hydrologists who study surfaces hydraulic properties. Thirdly, the high resolution of the BD Ortho IGN image emphasizes the heterogeneity inside the spatial entities. Thus, in urbanised areas, high-resolution imagery allows the precise identification of objects > 5 m2 and consequently the quantification of impervious and pervious surfaces. However, the continuity of forest areas is not maintained because of the presence of small entities with sparser tree cover that were classified as herbaceous areas. Finally, image characteristics are more crucial than classification methods for the accuracy of land cover mapping. However, object based approach improves the classification of mixed pixels on the edge between different objects. It's particularly true for buildings and roads.

Jacqueminet, Christine; Kermadi, Saïda; Michel, Kristell; Jankowfsky, Sonja; Braud, Isabelle; Branger, Flora; Beal, David; Gagnage, Matthieu

2010-05-01

72

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

73

Exploring the nutrient inputs and cycles in Tampa Bay and coastal watersheds using MODIS images and data mining  

NASA Astrophysics Data System (ADS)

Excessive nutrients, which may be represented as Total Nitrogen (TN) and Total Phosphorus (TP) levels, in natural water systems have proven to cause high levels of algae production. The process of phytoplankton growth which consumes the excess TN and TP in a water body can also be related to the changing water quality levels, such as Dissolved Oxygen (DO), chlorophyll-a, and turbidity, associated with their changes in absorbance of natural radiation. This paper explores spatiotemporal nutrient patterns in Tampa Bay, Florida with the aid of Moderate Resolution Imaging Spectroradiometer or MODIS images and Genetic Programming (GP) models that are deigned to link those relevant water quality parameters in aquatic environments.

Chang, Ni-Bin; Xuan, Zhemin

2011-09-01

74

Derivation of planetary topography using multi-image shape-from-shading  

USGS Publications Warehouse

In many cases, the derivation of high-resolution digital terrain models (DTMs) from planetary surfaces using conventional digital image matching is a problem. The matching methods need at least one stereo pair of images with sufficient texture. However, many space missions provide only a few stereo images and planetary surfaces often possess insufficient texture. This paper describes a method for the generation of high-resolution DTMs from planetary surfaces, which has the potential to overcome the described problem. The suggested method, developed by our group, is based on shape-from-shading using an arbitrary number of digital optical images, and is termed "multi-image shape-from-shading" (MI-SFS). The paper contains an explanation of the theory of MI-SFS, followed by a presentation of current results, which were obtained using images from NASA's lunar mission Clementine, and constitute the first practical application with our method using extraterrestrial imagery. The lunar surface is reconstructed under the assumption of different kinds of reflectance models (e.g. Lommel-Seeliger and Lambert). The represented results show that the derivation of a high-resolution DTM of real digital planetary images by means of MI-SFS is feasible. ?? 2006 Elsevier Ltd. All rights reserved.

Lohse, V.; Heipke, C.; Kirk, R.L.

2006-01-01

75

Baseline 18F-FDG PET image derived parameters for therapy response prediction in oesophageal cancer  

E-print Network

1 Baseline 18F-FDG PET image derived parameters for therapy response prediction in oesophageal for therapy response Keywords: oesophageal cancer, response to therapy, PET scan, tumour volume, total lesion of tumour measurements on 18F-FDG PET pretreatment scan regarding therapy response in oesophageal cancer

Paris-Sud XI, Université de

76

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

77

Integration of Color and Local Derivative Pattern Features for Content-Based Image Indexing and Retrieval  

NASA Astrophysics Data System (ADS)

This paper presents two new feature descriptors for content based image retrieval (CBIR) application. The proposed two descriptors are named as color local derivative patterns (CLDP) and inter color local derivative pattern (ICLDP). In order to reduce the computational complexity the uniform patterns are applied to both CLDP and ICLDP. Further, uniform CLDP (CLDPu2) and uniform ICLDP (ICLDPu2) are generated respectively. The proposed descriptors are able to exploit individual (R, G and B) spectral channel information and co-relating pair (RG, GB, BR, etc.) of spectral channel information. The retrieval performances of the proposed descriptors (CLDP and ICLDP) are tested by conducting two experiments on Corel-5000 and Corel-10000 benchmark databases. The results after investigation show a significant improvement in terms of precision, average retrieval precision (ARP), recall and average retrieval rate (ARR) as compared to local binary patterns (LBP), local derivative patterns (LDP) and other state-of-the-art techniques for image retrieval.

Vipparthi, Santosh Kumar; Nagar, Shyam Krishna

2014-09-01

78

Validation of spectral sky radiance derived from all-sky camera images - a case study  

NASA Astrophysics Data System (ADS)

Spectral sky radiance (380-760 nm) is derived from measurements with a Hemispherical Sky Imager (HSI) system. The HSI consists of a commercial compact CCD (charge coupled device) camera equipped with a fish-eye lens and provides hemispherical sky images in three reference bands such as red, green and blue. To obtain the spectral sky radiance from these images non-linear regression functions for various sky conditions have been derived. The camera-based spectral sky radiance was validated by spectral sky radiance measured with a CCD spectroradiometer. The spectral sky radiance for complete distribution over the hemisphere between both instruments deviates by less than 20% at 500 nm for all sky conditions and for zenith angles less than 80°. The reconstructed spectra of the wavelength 380 nm to 760 nm between both instruments at various directions deviate by less then 20% for all sky conditions.

Tohsing, K.; Schrempf, M.; Riechelmann, S.; Seckmeyer, G.

2014-01-01

79

Dependence of ventilation image derived from 4D CT on deformable image registration and ventilation algorithms.  

PubMed

Ventilation imaging using 4D CT is a convenient and low-cost functional imaging methodology which might be of value in radiotherapy treatment planning to spare functional lung volumes. Deformable image registration (DIR) is needed to calculate ventilation imaging from 4D CT. This study investigates the dependence of calculated ventilation on DIR methods and ventilation algorithms. DIR of the normal end expiration and normal end inspiration phases of the 4D CT images was used to correlate the voxels between the two respiratory phases. Three different DIR algorithms, optical flow (OF), diffeomorphic demons (DD), and diffeomorphic morphons (DM) were retrospectively applied to ten esophagus and ten lung cancer cases with 4D CT image sets that encompassed the entire lung volume. The three ventilation extraction methods were used based on either the Jacobian, the change in volume of the voxel, or directly calculated from Hounsfield units. The ventilation calculation algorithms used are the Jacobian, ?V, and HU method. They were compared using the Dice similarity coefficient (DSC) index and Bland-Altman plots. Dependence of ventilation images on the DIR was greater for the ?V and the Jacobian methods than for the HU method. The DSC index for 20% of low-ventilation volume for ?V was 0.33 ± 0.03 (1 SD) between OF and DM, 0.44 ± 0.05 between OF and DD, and 0.51 ± 0.04 between DM and DD. The similarity comparisons for Jacobian were 0.32 ± 0.03, 0.44 ± 0.05, and 0.51 ± 0.04, respectively, and for HU they were 0.53 ± 0.03, 0.56 ± 0.03, and 0.76 ± 0.04, respectively. Dependence of extracted ventilation on the ventilation algorithm used showed good agreement between the ?V and Jacobian methods, but differed significantly for the HU method. DSC index for using OF as DIR was 0.86 ± 0.01 between ?V and Jacobian, 0.28 ± 0.04 between ?V and HU, and 0.28 ± 0.04 between Jacobian and HU, respectively. When using DM or DD as DIR, similar values were obtained when comparing the different ventilation calculation methods. The similarity values for the 20% high-ventilation volume were close to those found for the 20% low-ventilation volume. The results obtained with DSC index were confirmed when using the Bland-Altman plots for comparing the ventilation images. Our data suggest that ventilation calculated from 4D CT depends on the DIR algorithm employed. Similarities between ?V and Jacobian are higher than between ?V and HU, and Jacobian and HU. PMID:23835389

Latifi, Kujtim; Forster, Kenneth M; Hoffe, Sarah E; Dilling, Thomas J; van Elmpt, Wouter; Dekker, Andre; Zhang, Geoffrey G

2013-01-01

80

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

81

Using Geotags to Derive Rich Tag-Clouds for Image Annotation  

NASA Astrophysics Data System (ADS)

Geotagging has become popular for many multimedia applications. In this chapter, we present an integrated and intuitive system for location-driven tag suggestion, in the form of tag-clouds, for geotagged photos. Potential tags from multiple sources are extracted and weighted. Sources include points of interest (POI) tags from a public Geographic Names Information System (GNIS) database, community tags from Flickr® pictures, and personal tags shared through users' own, family, and friends' photo collections. To increase the effectiveness of GNIS POI tags, bags of place-name tags are first retrieved, clustered, and then re-ranked using a combined tf-idf and spatial distance criteria. The community tags from photos taken in the vicinity of the input geotagged photo are ranked according to distance and visual similarity to the input photo. Personal tags from other personally related photos inherently carry a significant weight due more to their high relevance than to both the generic place-name tags and community tags, and are ranked by weights that decay over time and distance differences. Finally, a rich set of the most relevant location-driven tags is presented to the user in the form of individual tag clouds under the three mentioned source categories. The tag clouds act as intuitive suggestions for tagging an input image. We also discuss quantitative and qualitative findings from a user study that we conducted. Evaluation has revealed the respective benefits of the three categories toward the effectiveness of the integrated tag suggestion system.

Joshi, Dhiraj; Luo, Jiebo; Yu, Jie; Lei, Phoury; Gallagher, Andrew

82

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

83

In vivo Photoacoustic Spectroscopic Imaging of Hemoglobin Derivatives in Thermally Damaged Tissue  

NASA Astrophysics Data System (ADS)

Photoacoustic (PA) spectroscopic measurement was performed for thermally damaged skin in a rat in vivo to analyze hemoglobin derivatives in the tissue. We observed PA signals at around 500 and 633 nm, which are center wavelengths of methemoglobin (MetHb) absorption peaks, at depths corresponding the uppermost dermis (?0.16 mm) and hair follicles (?0.62 mm), indicating formation of MetHb in these tissue regions. By scanning a PA detector on the tissue, two-dimensional PA images (tomograms) were produced. Subtraction imaging technique was used for multispectral PA tomograms to analyze specific components of hemoglobin derivatives in the tissue, by which the contrast of oxyhemogobin (HbO2)-associated PA signal has been improved and the distribution of PA signal that seems to reflect the concentration of MetHb has been visualized.

Aizawa, Kazuya; Sato, Shunichi; Saitoh, Daizoh; Ashida, Hiroshi; Obara, Minoru

2009-06-01

84

Analysis of dynamic SPECT\\/CT measurements of the arterial input function in human subjects  

Microsoft Academic Search

Measurement of the arterial input function (AIF) is essential to deriving quantitative estimates of regional myocardial blood flow using kinetic models. Accurate measurements have been possible with a wide range of radiotracers in both research and clinical PET\\/CT imaging. However, accurate measurements of the AIF with dynamic SPECT or SPECT\\/CT have posed various challenges; foremost being that imaging a rapidly

Celeste D. Winant; Yuval R. Zelnik; Bryan W. Reutter; Arkadiusz Sitek; Steven L. Bacharach; Grant T. Gullberg; Carina Mari Aparici

2009-01-01

85

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

PubMed

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. PMID:22667620

Hashimoto, Seitaro; Kose, Katsumi; Haishi, Tomoyuki

2012-05-01

86

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

87

Evaluation of Existing Image Matching Methods for Deriving Glacier Surface Displacements Globally from Optical Satellite Imagery  

NASA Astrophysics Data System (ADS)

Automatic matching of images from two different times is a method that is often used to derive glacier surface velocity. Nearly global repeat coverage of the Earth's surface by optical satellite sensors now opens the possibility for global-scale mapping and monitoring of glacier flow with a number of applications in, for example, glacier physics, glacier-related climate change and impact assessment, and glacier hazard management. The purpose of this study is to compare and evaluate different existing image matching methods for glacier flow determination over large scales. The study compares six different matching methods: normalized cross-correlation (NCC), the phase correlation algorithm used in the COSI-Corr software, and four other Fourier methods with different normalizations. We compare the methods over five regions of the world with different representative glacier characteristics: Karakoram, the European Alps, Alaska, Pine Island (Antarctica) and southwest Greenland. Landsat images are chosen for matching because they expand back to 1972, they cover large areas, and at the same time their spatial resolution is as good as 15 m for images after 1999 (ETM+ pan). Cross-correlation on orientation images (CCF-O) outperforms the three similar Fourier methods, both in areas with high and low visual contrast. NCC experiences problems in areas with low visual contrast, areas with thin clouds or changing snow conditions between the images. CCF-O has problems on narrow outlet glaciers where small window sizes (about 16 pixels by 16 pixels or smaller) are needed, and it also obtains fewer correct matches than COSI-Corr in areas with low visual contrast. COSI-Corr has problems on narrow outlet glaciers and it obtains fewer correct matches compared to CCF-O when thin clouds cover the surface, or if one of the images contains snow dunes. In total, we consider CCF-O and COSI-Corr to be the two most robust matching methods for global-scale mapping and monitoring of glacier velocities. If combining CCF-O with locally adaptive template sizes and by filtering the matching results automatically by comparing the displacement matrix to its low pass filtered version, the matching process can be automated to a large degree. This allows the derivation of glacier velocities with minimal (but not without!) user interaction and hence also opens up the possibility of global-scale mapping and monitoring of glacier flow.

Heid, T.; Kääb, A.

2011-12-01

88

Arterial input function of an optical tracer for dynamic contrast enhanced imaging can be determined from pulse oximetry oxygen saturation measurements.  

PubMed

In many cases, kinetic modeling requires that the arterial input function (AIF)--the time-dependent arterial concentration of a tracer--be characterized. A straightforward method to measure the AIF of red and near-infrared optical dyes (e.g., indocyanine green) using a pulse oximeter is presented. The method is motivated by the ubiquity of pulse oximeters used in both preclinical and clinical applications, as well as the gap in currently available technologies to measure AIFs in small animals. The method is based on quantifying the interference that is observed in the derived arterial oxygen saturation (SaO?) following a bolus injection of a light-absorbing dye. In other words, the change in SaO? can be converted into dye concentration knowing the chromophore-specific extinction coefficients, the true arterial oxygen saturation, and total hemoglobin concentration. A simple error analysis was performed to highlight potential limitations of the approach, and a validation of the method was conducted in rabbits by comparing the pulse oximetry method with the AIF acquired using a pulse dye densitometer. Considering that determining the AIF is required for performing quantitative tracer kinetics, this method provides a flexible tool for measuring the arterial dye concentration that could be used in a variety of applications. PMID:23190567

Elliott, Jonathan T; Wright, Eric A; Tichauer, Kenneth M; Diop, Mamadou; Morrison, Laura B; Pogue, Brian W; Lee, Ting-Yim; St Lawrence, Keith

2012-12-21

89

Arterial input function of an optical tracer for dynamic contrast enhanced imaging can be determined from pulse oximetry oxygen saturation measurements  

NASA Astrophysics Data System (ADS)

In many cases, kinetic modeling requires that the arterial input function (AIF)—the time-dependent arterial concentration of a tracer—be characterized. A straightforward method to measure the AIF of red and near-infrared optical dyes (e.g., indocyanine green) using a pulse oximeter is presented. The method is motivated by the ubiquity of pulse oximeters used in both preclinical and clinical applications, as well as the gap in currently available technologies to measure AIFs in small animals. The method is based on quantifying the interference that is observed in the derived arterial oxygen saturation (SaO2) following a bolus injection of a light-absorbing dye. In other words, the change in SaO2 can be converted into dye concentration knowing the chromophore-specific extinction coefficients, the true arterial oxygen saturation, and total hemoglobin concentration. A simple error analysis was performed to highlight potential limitations of the approach, and a validation of the method was conducted in rabbits by comparing the pulse oximetry method with the AIF acquired using a pulse dye densitometer. Considering that determining the AIF is required for performing quantitative tracer kinetics, this method provides a flexible tool for measuring the arterial dye concentration that could be used in a variety of applications.

Elliott, Jonathan T.; Wright, Eric A.; Tichauer, Kenneth M.; Diop, Mamadou; Morrison, Laura B.; Pogue, Brian W.; Lee, Ting-Yim; St. Lawrence, Keith

2012-12-01

90

(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

91

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

92

Synthesis and evaluation of 18F labeled alanine derivatives as potential tumor imaging agents  

PubMed Central

Introduction This paper reports the synthesis and labeling of 18F alanine derivatives. We also investigate their biological characteristics as potential tumor imaging agents mediated by alanine-serine-cysteine preferring (ASC) transporter system. Methods Three new 18F alanine derivatives were prepared from corresponding tosylate-precursors through a two-step labelling reaction. In vitro uptake studies to evaluate and to compare these three analogs were carried out in 9L glioma and PC-3 prostate cancer cell lines. Potential transport mechanisms, protein incorporation and stability of 3-(1-[18F]fluoromethyl)-L-alanine (L[18F]FMA) were investigated in 9L glioma cells. Its biodistribution was determined in a rat-bearing 9L tumor model. PET imaging studies were performed on rat bearing 9L glioma tumors and transgenic mouse carrying spontaneous generated M/tomND tumor (mammary gland adenocarcinoma). Results New 18F alanine derivatives were prepared with 7–34% uncorrected radiochemical yields, excellent enantiomeric purity (>99%) and good radiochemical purity (>99%). In vitro uptake of the L-[18F]FMA in 9L glioma and PC-3 prostate cancer cells was higher than those observed for other two alanine derivatives and [18F]FDG in first 1 h. Inhibition of cell uptake studies suggested that L-[18F]FMA uptake in 9L glioma was predominantly via transport system ASC. After entering into cells, L-[18F]FMA remained stable and was not incorporated into protein within 2 h. In vivo biodistribution studies demonstrated that L-[18F]FMA had relatively high uptake in liver and kidney. Tumor uptake was fast, reaching a maximum within 30 min. The tumor-to-muscle, tumor-to-blood and tumor-to-brain ratios at 60 min post injection were 2.2, 1.9 and 3.0, respectively. In PET imaging studies, tumors were visualized with L-[18F]FMA in both 9L rat and transgenic mouse. Conclusion L-[18F]FMA showed promising properties as a PET imaging agent for up-regulated ASC transporter associated with tumor proliferation. PMID:22542392

Wang, Limin; Zha, Zhihao; Qu, Wenchao; Qiao, Hongwen; Lieberman, Brian P.; Plossl, Karl; Kung, Hank F.

2012-01-01

93

Hierarchy of Electronic Properties of Chemically Derived and Pristine Graphene Probed by Microwave Imaging  

SciTech Connect

Local electrical imaging using microwave impedance microscope is performed on graphene in different modalities, yielding a rich hierarchy of the local conductivity. The low-conductivity graphite oxide and its derivatives show significant electronic inhomogeneity. For the conductive chemical graphene, the residual defects lead to a systematic reduction of the microwave signals. In contrast, the signals on pristine graphene agree well with a lumped-element circuit model. The local impedance information can also be used to verify the electrical contact between overlapped graphene pieces.

Kundhikanjana, W.

2010-06-02

94

In vivo bioluminescence imaging of cord blood derived mesenchymal stem cell transplantation into rat myocardium  

Microsoft Academic Search

Objective  The conventional method for the analysis of myocardial cell transplantation depends on postmortem histology. Here, we have\\u000a sought to demonstrate the feasibility of a longitudinal monitoring of transplanted cell survival in living animals, accomplished\\u000a with optical imaging techniques and pharmacological interventions.\\u000a \\u000a \\u000a \\u000a Methods  Human cord blood (50 ml) was donated with parental consent. After getting cord blood derived mesenchymal stem cells (CBMSCs),

Jung-Joon Min; Sungmin Moon; Sung Mi Kim; Hee-Seung Bom; Uyenchi N. Le; Youngkeun Ahn; Yong Sook Kim; Soo Yeon Joo; Moon Hwa Hong; Myung Ho Jeong; Chang Hun Song; Jong Eun Park; Joseph C. Wu; Deok Hwan Yang; Yun Hyeok Jeong; Kyung-Sun Kang; Kyung Yeon Yoo

2006-01-01

95

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

96

Decomposition of satellite-derived images for the distinction of cloud types' features  

NASA Astrophysics Data System (ADS)

Linear filtering methods using convolution techniques are applied in computer vision, to detect spatial discontinuities in the intensity of luminance of photograph images. These techniques are based on the following principal: a pixel's neighborhood contains information about its intensity. The variation of this intensity provides some information about the distribution and the possible decomposition of the image in various features. This decomposition relies on the relative position of the pixel (edge or not) on the image. These principals, integrated into remote sensing analyses, are applied in this study to differentiate cloud morphological features representing cloud types from a thermal image product (the Cloud top temperatures) derived from polar orbit satellites' observations. This approach contrast with that of other techniques commonly used in satellite cloud classification, and based on optical or thermodynamic properties of the clouds. The interpretation of the distribution of these cloud morphological features, and their frequency is evaluated against another cloud classification method relying on cloud optical properties. The results show a relatively good match between the two classifications. Implications of these results, on the estimation of the impact of cloud shapes' variations on the recent climate are discussed.

Dim, Jules R.; Murakami, Hiroshi

2013-02-01

97

Eur J Nucl Med Mol Imaging . Author manuscript Baseline F-FDG PET image-derived parameters for therapy response18  

E-print Network

to therapy ; PET scan ; tumour volume ; total lesion glycolysis Introduction Oesophageal cancer is the thirdEur J Nucl Med Mol Imaging . Author manuscript Page /1 16 Baseline F-FDG PET image-derived parameters for therapy response18 prediction in oesophageal cancer Mathieu Hatt 1 * , Dimitris Visvikis 1

Paris-Sud XI, Université de

98

The natural input memory model  

Microsoft Academic Search

A new recognition memory model is proposed which differs from the existing memory models in that it operates on natural input. Therefore it is called the natural input memory (N IM) model. A biologically-informed perceptual pre-processing method takes local samples from a natural image and translates these into a feature-vector representation. The feature-vector representations reside in a similarity space in

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

2005-01-01

99

Novel Positively Charged Nanoparticle Labeling for In Vivo Imaging of Adipose Tissue-Derived Stem Cells  

PubMed Central

Stem cell transplantation has been expected to have various applications for regenerative medicine. However, in order to detect and trace the transplanted stem cells in the body, non-invasive and widely clinically available cell imaging technologies are required. In this paper, we focused on magnetic resonance (MR) imaging technology, and investigated whether the trimethylamino dextran-coated magnetic iron oxide nanoparticle -03 (TMADM-03), which was newly developed by our group, could be used for labeling adipose tissue-derived stem cells (ASCs) as a contrast agent. No cytotoxicity was observed in ASCs transduced with less than 100 µg-Fe/mL of TMADM-03 after a one hour transduction time. The transduction efficiency of TMADM-03 into ASCs was about four-fold more efficient than that of the alkali-treated dextran-coated magnetic iron oxide nanoparticle (ATDM), which is a major component of commercially available contrast agents such as ferucarbotran (Resovist), and the level of labeling was maintained for at least two weeks. In addition, the differentiation ability of ASCs labeled with TMADM-03 and their ability to produce cytokines such as hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and prostaglandin E2 (PGE2), were confirmed to be maintained. The ASCs labeled with TMADM-03 were transplanted into the left kidney capsule of a mouse. The labeled ASCs could be imaged with good contrast using a 1T MR imaging system. These data suggest that TMADM-03 can therefore be utilized as a contrast agent for the MR imaging of stem cells. PMID:25365191

Yukawa, Hiroshi; Nakagawa, Shingo; Yoshizumi, Yasuma; Watanabe, Masaki; Saito, Hiroaki; Miyamoto, Yoshitaka; Noguchi, Hirofumi; Oishi, Koichi; Ono, Kenji; Sawada, Makoto; Kato, Ichiro; Onoshima, Daisuke; Obayashi, Momoko; Hayashi, Yumi; Kaji, Noritada; Ishikawa, Tetsuya; Hayashi, Shuji; Baba, Yoshinobu

2014-01-01

100

High-resolution digital elevation models derived from Viking Orbiter images: Method and comparison with Mars Orbiter Laser Altimeter  

E-print Network

and comparison with Mars Orbiter Laser Altimeter Data D. Baratoux, C. Delacourt and, P. Allemand Laboratoire des local and high-resolution digital elevation models (DEM) of Mars from Viking Orbiter images. We focus1 High-resolution digital elevation models derived from Viking Orbiter images: Method

Delacourt, Christophe

101

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

102

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

103

Monitoring tropical cyclone intensity using wind fields derived from short-interval satellite images  

NASA Technical Reports Server (NTRS)

Rapid scan visible images from the Visible Infrared Spin Scan Radiometer sensor on board SMS-2 and GOES-1 were used to derive high resolution upper and lower tropospheric environmental wind fields around three western Atlantic tropical cyclones (1975-78). These wind fields were used to derive upper and lower tropospheric areal mean relative vorticity and their differences, the net relative angular momentum balance and upper tropospheric mass outflow. These kinematic parameters were shown by studies using composite rawinsonde data to be strongly related to tropical cyclone formation and intensity changes. Also, the role of forced synoptic scale subsidence in tropical cyclone formation was examined. The studies showed that satellite-derived lower and upper tropospheric wind fields can be used to monitor and possibly predict tropical cyclone formation and intensity changes. These kinematic analyses showed that future changes in tropical cyclone intensity are mainly related to the "spin-up" of the storms by the net horizontal transport of relative angular momentum caused by convergence of cyclonic vorticity in the lower troposphere and to a lesser extent the divergence of anticyclone vorticity in the upper troposphere.

Rodgers, E. B.; Gentry, R. C.

1981-01-01

104

Derivatives of dibenzothiophene for PET imaging of ?7-Nicotinic Acetylcholine Receptors  

PubMed Central

A new series of derivatives of 3-(1,4-diazabicyclo[3.2.2]nonan-4-yl)dibenzo[b,d]thiophene 5,5-dioxide with high binding affinities and selectivity for ?7-nicotinic acetylcholine receptors (?7-nAChRs) (Ki = 0.4 – 20 nM) has been synthesized for PET imaging of ?7-nAChRs. Two radiolabeled members of the series [18F]7a (Ki = 0.4 nM) and [18F]7c (Ki = 1.3 nM) were synthesized. [18F]7a and [18F]7c readily entered the mouse brain and specifically labeled ?7-nAChRs. The ?7-nAChR selective ligand 1 (SSR180711) blocked the binding of [18F]7a in the mouse brain in a dose-dependent manner. The mouse blocking studies with non-?7-nAChR CNS drugs demonstrated that [18F]7a is highly ?7-nAChR selective. In agreement with its binding affinity the binding potential of [18F]7a (BPND = 5.3 – 8.0) in control mice is superior to previous ?7-nAChR PET radioligands. Thus, [18F]7a displays excellent imaging properties in mice and has been chosen for further evaluation as a potential PET radioligand for imaging of ?7-nAChR in non-human primates. PMID:24050653

Gao, Yongjun; Kellar, Kenneth J.; Yasuda, Robert P.; Tran, Thao; Xiao, Yingxian; Dannals, Robert F.; Horti, Andrew G.

2013-01-01

105

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 ?E(ST) 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

106

Enhancing Proprioceptive Input to Motoneurons Differentially Affects Expression of Neurotrophin 3 and Brain-Derived Neurotrophic Factor in Rat Hoffmann-Reflex Circuitry  

PubMed Central

The importance of neurotrophin 3 (NT-3) for motor control prompted us to ask the question whether direct electrical stimulation of low-threshold muscle afferents, strengthening the proprioceptive signaling, could effectively increase the endogenous pool of this neurotrophin and its receptor TrkC in the Hoffmann-reflex (H-reflex) circuitry. The effects were compared with those of brain-derived neurotrophic factor (BDNF) and its TrkB receptor. Continuous bursts of stimuli were delivered unilaterally for seven days, 80 min daily, by means of a cuff-electrode implanted over the tibial nerve in awake rats. The H-reflex was recorded in the soleus muscle to control the strength of stimulation. Stimulation aimed at activation of Ia fibers produced a strong increase of NT-3 protein, measured with ELISA, in the lumbar L3-6 segments of the spinal cord and in the soleus muscle. This stimulation exerted much weaker effect on BDNF protein level which slightly increased only in L3-6 segments of the spinal cord. Increased protein level of NT-3 and BDNF corresponded to the changes of NT-3 mRNA and BDNF mRNA expression in L3-6 segments but not in the soleus muscle. We disclosed tissue-specificity of TrkC mRNA and TrkB mRNA responses. In the spinal cord TrkC and TrkB transcripts tended to decrease, whereas in the soleus muscle TrkB mRNA decreased and TrkC mRNA expression strongly increased, suggesting that stimulation of Ia fibers leads to sensitization of the soleus muscle to NT-3 signaling. The possibility of increasing NT-3/TrkC signaling in the neuromuscular system, with minor effects on BDNF/TrkB signaling, by means of low-threshold electrical stimulation of peripheral nerves, which in humans might be applied in non-invasive way, offers an attractive therapeutic tool. PMID:23776573

Gajewska-Wozniak, Olga; Skup, Malgorzata; Kasicki, Stefan; Ziemlinska, Ewelina; Czarkowska-Bauch, Julita

2013-01-01

107

Bis-pyridinium quadrupolar derivatives. High Stokes shift selective probes for bio-imaging  

NASA Astrophysics Data System (ADS)

We describe the design, synthesis and characterization of five high Stokes shift quadrupolar heteroaryl compounds suitable as fluorescent probes in bio-imaging. In particular, we characterize the photophysical properties and the intracellular localization in Human Umbilical Vein Endothelial Cells (HUVEC) and Human Mesenchymal Stem Cells (HMSCs) for each dye. We show that, amongst all of the investigated derivatives, the 2,5-bis[1-(4-N-methylpyridinium)ethen-2-yl)]- N-methylpyrrole salt is the best candidates as selective mitochondrial tracker. Finally, we recorded the full emission spectrum of the most performing - exclusively mitochondrial selective - fluorescent probe directly from HUVEC stained cells. The emission spectrum collected from the stained mitochondria shows a remarkably more pronounced vibronic structure with respect to the emission of the free fluorophore in solution.

Salice, Patrizio; Versari, Silvia; Bradamante, Silvia; Meinardi, Francesco; Macchi, Giorgio; Pagani, Giorgio A.; Beverina, Luca

2013-11-01

108

Eur J Nucl Med Mol Imaging . Author manuscript The age of reason for FDG PET image-derived indices  

E-print Network

; therapy response The clinical use of Positron Emission Tomography (PET) imaging using the 2-deoxy-2-(18F interest in the use of 18F-FDG PET imaging for the prediction and monitoring of therapy response. WithinEur J Nucl Med Mol Imaging . Author manuscript Page /1 3 The age of reason for FDG PET image

Paris-Sud XI, Université de

109

A study on the topological derivative-based imaging of thin electromagnetic inhomogeneities in limited-aperture problems  

NASA Astrophysics Data System (ADS)

The topological derivative-based non-iterative imaging algorithm has demonstrated its applicability in limited-aperture inverse scattering problems. However, this has been confirmed through many experimental simulation results, and the reason behind this applicability has not been satisfactorily explained. In this paper, we identify the mathematical structure and certain properties of topological derivatives for the imaging of two-dimensional crack-like thin penetrable electromagnetic inhomogeneities that are completely embedded in a homogeneous material. To this end, we establish a relationship with an infinite series of Bessel functions of integer order of the first kind. Based on the derived structure, we discover a necessary condition for applying topological derivatives in limited-aperture inverse scattering problems, and thus confirm why topological derivatives can be applied. Furthermore, we analyze the structure of multi-frequency topological derivative, and identify why this improves the single-frequency topological derivative in limited-aperture inverse scattering problems. Various numerical simulations are conducted with noisy data, and the results support the derived structure and exhibit certain properties of single- and multi-frequency topological derivatives.

Ahn, Chi Young; Jeon, Kiwan; Ma, Yong-Ki; Park, Won-Kwang

2014-10-01

110

A Quantitative Comparison of Traditional and Image-Derived Bathymetry From Landsats 5, 7, and 8  

NASA Astrophysics Data System (ADS)

Though the ocean covers 70% of the earth and is a prime driver of our climate, roughly 95% of it is unexplored. As a basic geophysical parameter, accurate and sufficiently detailed bathymetry is a key piece in understanding the oceans and coasts. Moreover, coastal bathymetry in particular can change rapidly in response to storms, sea level rise, changes in river conditions, and engineering activity. Because of the expense and time involved with traditional, though very accurate, bathymetric methods, remote sensing imagery-derived measurement is often used as a technique for in-fill or rapid response to bathymetry-changing events. While imagery-based bathymetry has been in use for many decades, the techniques and imaging platforms have both evolved and improved over the years. Landsat 8, with its added coastal band, 12-bit capability, 2-week revisit, and global coverage, is an important step forward in updating coastal morphology maps and extending them in to less well-known coastal waters. Here, we present results quantitatively comparing Landsat 5, Landsat 7, and Landsat 8 to sonar-derived bathymetry.

Hulslander, D.

2013-12-01

111

Magnetic resonance velocity imaging derived pressure differential using control volume analysis  

PubMed Central

Background Diagnosis and treatment of hydrocephalus is hindered by a lack of systemic understanding of the interrelationships between pressures and flow of cerebrospinal fluid in the brain. Control volume analysis provides a fluid physics approach to quantify and relate pressure and flow information. The objective of this study was to use control volume analysis and magnetic resonance velocity imaging to non-invasively estimate pressure differentials in vitro. Method A flow phantom was constructed and water was the experimental fluid. The phantom was connected to a high-resolution differential pressure sensor and a computer controlled pump producing sinusoidal flow. Magnetic resonance velocity measurements were taken and subsequently analyzed to derive pressure differential waveforms using momentum conservation principles. Independent sensor measurements were obtained for comparison. Results Using magnetic resonance data the momentum balance in the phantom was computed. The measured differential pressure force had amplitude of 14.4 dynes (pressure gradient amplitude 0.30 Pa/cm). A 12.5% normalized root mean square deviation between derived and directly measured pressure differential was obtained. These experiments demonstrate one example of the potential utility of control volume analysis and the concepts involved in its application. Conclusions This study validates a non-invasive measurement technique for relating velocity measurements to pressure differential. These methods may be applied to clinical measurements to estimate pressure differentials in vivo which could not be obtained with current clinical sensors. PMID:21414222

2011-01-01

112

Synthesis and preliminary evaluation of 2-arylhydroxyquinoline derivatives for tau imaging.  

PubMed

Alzheimer's disease (AD) is the most common cause of dementia. Senile plaques, consisting of ?-amyloid, and neurofibrillary tangles (NFTs), composed of tau protein, are representative pathological hallmarks of AD. It is believed that the accumulation of NFTs precedes the onset of clinical symptoms of AD and correlates with the progression of memory dysfunction. Thus, the use of noninvasive detection techniques including radiolabeled probes and positron emission tomography (PET) will facilitate early diagnosis or staging of AD. In this study, we synthesized and evaluated novel hydroxylated 2-arylquinoline derivatives as tau imaging PET probes. The binding affinities of compounds for tau were evaluated by fluorescent staining of the AD hippocampal section and a competitive binding assay using [(18) F]THK-523. THK-951 showed high binding affinity for tau pathology in an AD brain section and K18?280K fibrils (Ki ?=?20.7?nM); thus, we radiosynthesized a (11) C-labeled THK-951 and further studied its potential as a tau PET probe. The [(11) C]THK-951 demonstrated excellent kinetics in a normal mouse brain (3.23% ID/g at 2?min postinjection and 0.15% ID/g at 30?min postinjection) and showed the labeling of NFTs in an AD brain section by autoradiography assay. These findings indicate the availability of [(11) C]THK-951 for in vivo PET imaging of tau pathology in AD. PMID:24448742

Tago, Tetsuro; Furumoto, Shozo; Okamura, Nobuyuki; Harada, Ryuichi; Ishikawa, Yoichi; Arai, Hiroyuki; Yanai, Kazuhiko; Iwata, Ren; Kudo, Yukitsuka

2014-01-01

113

Brain imaging: Reduced sensitivity of RARE-derived techniques to susceptibility effects  

SciTech Connect

Our goal was to evaluate the decreased sensitivity of RARE-derived pulse sequences to susceptibility effects. A variety of RARE-derived T2-weighted fast SE echo (FSE) sequences with echo trains from 6 to 16 were compared with conventional SE (CSE) sequences by means of MRI in phantoms (iron oxides), volunteers (n = 10), and patients (n = 13) with old hemorrhagic brain lesions. All experiments were performed on a 1.5 T clinical MR system (Magnetom SP 4000; Siemens AG, Erlangen, Germany) with constant imaging parameters. Contrast-to-noise ratios (CNRs) of tubes doped with iron oxides at different concentrations and brain areas with physiological iron deposition (red nucleus, substantia nigra) were calculated for CSE and FSE pulse sequences. Areas of old brain hemorrhage were analyzed for lesion conspicuity by blinded analysis with CSE as an internal standard. CNR of iron oxide tubes (TE 90 ins, CSE 45.0 {+-} 3.5, FSE 16 echo trains 28.5 {+-} 3. 1; p {le} 0.01) and iron-containing brain areas decreased with increasing echo trains of FSE sequences. A significantly lower number of old hemorrhagic brain lesions was visible in patients scanned with FSE sequences (6 echo trains: n = 28; 16 echo trains: n = 26) than CSE (n = 40). Our results demonstrate that the sensitivity of RARE-derived techniques to susceptibility effects is significantly decreased compared with CSE. CSE sequences or GE sequences should still be preferred in patients with a history of seizures or intracranial hemorrhage. 25 refs., 3 figs., 1 tabs.

Reimer, P.; Allkemper, T.; Schuierer, G.; Peters, P.E. [Westfalian Wilhelms-Univ. Muenster, Muenster (Germany)] [Westfalian Wilhelms-Univ. Muenster, Muenster (Germany)

1996-03-01

114

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

NASA Astrophysics Data System (ADS)

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 of 7.5d in latitude and longitude covering +/-60° in latitude and central meridian distance and combine them to make synoptic flow maps. We begin exploring the dynamics of the near-surface layers and the interaction between flows and magnetic flux by deriving fluid dynamics descriptors such as divergence and vorticity from these flow maps. Using these descriptors, we derive the vertical velocity component and the kinetic helicity density. For this particular Carrington rotation, we find that the vertical velocity component is anticorrelated with the unsigned magnetic flux. Strong downflows are more likely associated with locations of strong magnetic activity. The vertical vorticity is positive in the northern hemisphere and negative in the southern hemisphere. At locations of magnetic activity, we find an excess vorticity of the same sign as that introduced by differential rotation. The vertical gradient of the zonal flow is mainly negative except within 2 Mm of the surface at latitudes poleward of about 20°. The zonal-flow gradient appears to be related to the unsigned magnetic flux in the sense that locations of strong activity are also locations of large negative gradients. The vertical gradient of the meridional flow changes sign near about 7 Mm, marking a clear distinction between near-surface and deeper layers. GONG and MDI data show very similar results. Differences occur mainly at high latitudes, especially in the northern hemisphere, where MDI data show a counter cell in the meridional flow that is not present in the corresponding GONG data.

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

2004-04-01

115

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

116

Kalman filter input estimation  

NASA Astrophysics Data System (ADS)

As system output includes information concerning system input, it seems possible that system output can be used to estimate noisy system input. For Single Input Single Output (SISO) systems, the problem of input estimation using a Kalman filter is examined. Since the problem is different from an ordinary Kalman filter problem, it is first modified to an ordinary Kalman filter problem, and the input estimation accuracy is then calculated from the measurement accuracy through the Riccati equation. The input accuracy for an integrator system is analyzed, and a sinusoidal input is estimated using the simulated output of an integrator system.

Sasa, Shuuichi; Nagayasu, Masahiko

1992-11-01

117

Input-based Language Modelling in the Design of High Performance Text Input Techniques  

Microsoft Academic Search

We present a critique of language-based modelling for text input research, and propose an alternative input- based approach. Current language-based statistical models are derived from large samples of text (corpora). However, this text reflects only the output, or final result, of the text input task. We argue that this weakens the utility of the model, because, (1) users' language is

R. William Soukoreff; I. Scott Mackenzie

2003-01-01

118

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

NASA Astrophysics Data System (ADS)

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 to the forward problem for breasts containing 'added pathologies', representing tumors, to breasts lacking these inclusions. Both breast size and its optical properties have been examined in tissue. In each case, two small simulated tumors were 'added' to the background issue. Values of absorption and scattering coefficients of the tumors have been examined that are both greater and less than the surrounding tissue. Detector responses and the required imaging operators were computed by numerically solving the diffusion equation for inhomogeneous media. Detectors were distributed uniformly, in a circular fashion, around the breast in a plane positioned parallel and half-way between the chest wall and the nipple. A total of 20 sources were used, and for each 20 detectors. Reconstructed images were obtained by solving a linear perturbation equation derived from transport theory. Three algorithms were tested to solve the perturbation equation and include, the methods of conjugate gradient decent (CGD), projection onto convex sets (POCS), and simultaneous algebraic reconstruction technique (SART). Results obtained showed that in each case, high quality reconstructions were obtained. The computed images correctly resolved and identified the spatial position of the two tumors. Additional studies showed that computed images were stable to large systematic errors in the imaging operators and to added noise. Further, examination of the computed detector readings indicate that images of tissue up to approximately 10 cm in thickness should be possible. The results reported are the first to demonstrate that high quality images of small added inclusions can be obtained from anatomically accurate models of thick tissues having arbitrary boundaries based on the analysis of diffusely sscattered light.

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

1995-05-01

119

Structure-function correlation and biostability of antibody CDR-derived peptides as tumour imaging agents.  

PubMed

Based on the CDR3 V(H) sequence of a monoclonal antibody (ASM2) raised against epithelial cancer cells, the synthetic peptide YCAREPPTRTFAYWG (EPPT1) has been found to have an appreciable affinity (Kd = 20 microM) for the deglycosylated mucin-derived peptide antigen YVTSAPDTRPAPGST (PDTRP). The technetium-radiolabelled form of this peptide has been found to be a good tumour-imaging candidate for diagnosis of breast carcinoma. Several EPPT1 peptide analogues were synthesised. A differential biostability was obtained blocking the end groups of EPPT1. The susceptibility to proteolytic degradation was significantly decreased for the C-amidated form of EPPT1 than the N-acetylated form. Using resonant mirror biosensor technique, the EPPT1 analogues were classified as active and non-active peptides according to their PDTRP-binding properties. The binding of EPPT1 to PDTRP in free solution was also determined unambiguously by CD spectroscopy. CD spectra of both active and non-active peptides showed the presence of irregular conformations in H2) and SDS above cmc. In TFE, significant degree of ordered conformations of alpha-helix or beta-turn type were induced but did not correlate well with their binding properties. In SDS below cmc a conformational difference was observed between the active and non-active peptides. The active peptides exhibited CD spectra of aggregation of beta-strand type whilst the non-active showed CD spectra similar to those in H2O and SDS above cmc, critical micelle concentration. A good correlation between the extended conformation of beta-strand type and the binding affinity of the active peptides suggests this conformation as the binding feature of the EPPT tumour-imaging peptides. These information are vital for the design of novel EPPT analogues. Any modification to improve binding affinity must retain the ability of the peptides to adopt the extended conformation of beta-strand type. PMID:9575342

Hussain, R; Courtenay-Luck, N S; Siligardi, G

120

Deriving statistical significance maps for SVM based image classification and group comparisons  

PubMed Central

Population based pattern analysis and classification for quantifying structural and functional differences between diverse groups has been shown to be a powerful tool for the study of a number of diseases, and is quite commonly used especially in neuroimaging. The alternative to these pattern analysis methods, namely mass univariate methods such as voxel based analysis and all related methods, cannot detect multivariate patterns associated with group differences, and are not particularly suitable for developing individual-based diagnostic and prognostic biomarkers. A commonly used pattern analysis tool is the support vector machine (SVM). Unlike univariate statistical frameworks for morphometry, analytical tools for statistical inference are unavailable for the SVM. In this paper, we show that null distributions ordinarily obtained by permutation tests using SVMs can be analytically approximated from the data. The analytical computation takes a small fraction of the time it takes to do an actual permutation test, thereby rendering it possible to quickly create statistical significance maps derived from SVMs. Such maps are critical for understanding imaging patterns of group differences and interpreting which anatomical regions are important in determining the classifier's decision. PMID:23285616

Gaonkar, Bilwaj; Davatzikos, Christos

2013-01-01

121

Automatic Identification and Truncation of Boundary Outlets in Complex Imaging-Derived Biomedical Geometries  

PubMed Central

Efficient and accurate reconstruction of imaging-derived geometries and subsequent quality mesh generation are enabling technologies for both clinical and research simulations. A challenging part of this process is the introduction of computable, orthogonal boundary patches, namely the outlets, into treed structures, such as vasculature, arterial or airway trees. We present efficient and robust algorithms for automatically identifying and truncating the outlets for complex geometries. Our approach is based on a conceptual decomposition of objects into tips, segments, and branches, where the tips determine the outlets. We define the tips by introducing a novel concept called the average interior center of curvature (AICC) and identify the tips that are stable and noise resistant. We compute well-defined orthogonal planes, which truncate the tips into outlets. The rims of the outlets are connected into curves, and the outlets are then closed using Delaunay triangulation. We illustrate the effectiveness and robustness of our approach with a variety of complex lung and coronary artery geometries. PMID:19526263

Jiao, Xiangmin; Einstein, Daniel R.; Dyedov, Vladimir; Carson, James P.

2009-01-01

122

Imaging of hydrogen peroxide generation in cultured cells using dichlorofluorescein derivatives  

NASA Astrophysics Data System (ADS)

There is growing evidence that generation of reactive oxygen molecules (e.g., hydrogen peroxide, superoxide, hydroxyl and nitric oxide radicals) plays an important role in cell death. In this report we evaluated the effectiveness of the membrane permeable probe carboxy- dichlorodihydrofluorescein diacetate acetoxymethyl ester (C-DCDHF-DA-AM) for imaging the production of H2O2 in cultured cells. We examined the properties of three derivatives of the ester in saline droplets and compared the results with responses recorded from cells loaded with the ester. Results indicated that fluorescence was generated in cells and droplets by a photo-oxidative process involving H2O2. Videomicroscopy demonstrated that the cellular responses originated in small vesicles (presumably peroxisomes), with large responses filling the cytosol and enveloping the nucleus. We interpreted these responses as due to light-induced activation of flavin-containing oxidases, which generate H2O2 in peroxisomes, followed by diffusion of H2O2 throughout the cell. Escape of H2O2 from peroxisomes into Fe2+-containing compartments could have dire consequences on cell viability due to the production of hydroxyl free radicals. Such a mechanism could underly the phototoxic effects of visible light on cultured cells.

Hockberger, Philip E.; Ahmed, Mohammed S.; Skimina, Timothy A.; Lee, Christopher; Hung, Wu-Yen; Siddique, Tippu

1996-05-01

123

Automatic Input Rectification  

E-print Network

We present a novel technique, automatic input rectification, and a prototype implementation called SOAP. SOAP learns a set of constraints characterizing typical inputs that an application is highly likely to process ...

Long, Fan

2011-10-03

124

Automatic input rectification  

E-print Network

We present a novel technique, automatic input rectification, and a prototype implementation, SOAP. SOAP learns a set of constraints characterizing typical inputs that an application is highly likely to process correctly. ...

Long, Fan, S.M. Massachusetts Institute of Technology

2012-01-01

125

Automatic input rectification  

E-print Network

We present a novel technique, automatic input rectification, and a prototype implementation, SOAP. SOAP learns a set of constraints characterizing typical inputs that an application is highly likely to process correctly. ...

Long, Fan

126

Medical image fusion by wavelet transform modulus maxima  

Microsoft Academic Search

Medical image fusion has been used to derive useful information from multimodality medical image data. In this research, we propose a novel method for multimodality medical image fusion. Using wavelet transform, we achieved a fusion scheme. Afusion rule is proposed and used for calculating the wavelet transformation modulus maxima of input images at different bandwidths and levels. To evaluate the

Qu Guihong; Zhang Dali; Yan Pingfan

2001-01-01

127

A statistical protocol for describing global land-cover characterizations derived from remotely-sensed images  

NASA Astrophysics Data System (ADS)

Statistical measures are evaluated and recommended for use in a protocol to describe land-cover characterizations (often with more than 100 classes), to identify classes needing further evaluation, and to support mapping the land-cover characterization classes into user-specified land-cover classes (often with fewer than 20 classes). The data sets studied are the Land-Cover Characterization database derived from AVHRR images (1992--1993) for the conterminous U.S., the USGS Land-Use Land-Cover database derived from aerial photography (1960s and 1970s), and the USFS coordinated ground-sampled Land-Cover Characterization Validation database (1993--1994). A set of overall, class-specific and class-pairs measures of association with distinct statistical properties is incorporated into the protocol. Three overall measures, Proportional Reduction in Error (PRE), Proportion of Explained Variance (PEV), and Cramer's V, quantify the relationship between land-cover characterizations and landcover classifications. Using a Monte Carlo simulation, at sample sizes less than 0.1% the population parameters are no longer contained within the interquartile range of the estimates. Standardized conditional variants of PEV and PRE are used to identify classes whose distributions of counts differ statistically from the marginal frequencies. The Chi-square, correlation coefficient, Yule's Q and deviance residuals quantify the associations between land-cover characterization and land-cover classification class-pairs. The Chi-square statistic identifies statistically independent class-pairs. The other three measures allow class-pairs to be ranked. The protocol was used to compare the three data sets for 2,523 sample plots (0.0327% of the population). The Land-Cover Characterization was slightly more closely associated with the USGS classification than was the USFS classification. The strongest associations for each Land-Cover Characterization class, in general, support the interpreted land-cover labels. A few Land-Cover Characterization classes with no, or only weak, associations with the interpreted class warrant further analysis. A comparison of the reference classifications identified potential sources of confusion. Techniques described in the remote-sensing literature for the analysis of contingency tables are designed to assess accuracy or agreement. The protocol and measures described in this dissertation provide a valuable set of tools for use by the resource scientist to efficiently and effectively handle the very large number of classes and relationships that exist in general global land-cover characterizations.

Fosnight, Eugene Alan

128

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

129

Docking study, synthesis, and in vitro evaluation of fluoro-MADAM derivatives as SERT ligands for PET imaging.  

PubMed

In order to predict affinity of new diphenylsulfides for the serotonin transporter (SERT), a molecular modeling model was used to compare potential binding affinity of new compounds with known potent ligands. The aim of this study is to identify a suitable PET radioligand for imaging the SERT, new derivatives, and their precursors for a C-11 or F-18 radiolabeling, were synthesized. Two fluorinated derivatives displayed good in vitro affinity for the SERT (K(i)=14.3+/-1 and 10.1+/-2.7 nM) and good selectivity toward the other monoamine transporters as predicted by the docking study. PMID:18793858

Mavel, Sylvie; Vercouillie, Johnny; Garreau, Lucette; Raguza, Tiziana; Ravna, Aina Westrheim; Chalon, Sylvie; Guilloteau, Denis; Emond, Patrick

2008-10-01

130

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

131

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

132

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

133

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

134

Derivation of New Emission Factors for Quantification of Mass Emissions When Using Optical Gas Imaging for Detecting Leaks  

Microsoft Academic Search

This paper describes the development of new “leak\\/no-leak” emission factors that are suitable for estimating facilities’ fugitive emissions when using an alternative work practice (AWP) that is based on optical gas imaging technology for detecting leaking piping system components. These emission factors were derived for valves, pumps, and connectors\\/flanges for instrument leak detection thresholds ranging from 3 to 60 g\\/hr

Miriam Lev-On; David Epperson; Jeffrey Siegell; Karin Ritter; Norman Robinson; Dana Trimble; Steven Kohl; John Watson; L.-W. Chen; M. C. Chang; Hsing-Wang Li; Yee-Lin Wu; Wen-Jhy Lee; Guo-Ping Chang-Chien; Joao Gomes; Joana Nascimento; Helena Rodrigues; David Schaad; James Halley; Vince Alaimo; Hal Taback; Yu Zhou; Lixin Fu; Linglin Cheng; Pao-Wen Liu; Daniel Brady; Gregory Pratt; Qingzhong Yuan; Kalliat Valsaraj; Danny Reible; Clinton Willson; Wipada Sanongraj; Yongsheng Chen; John Crittenden; Hugo Destaillats; David Hand; David Perram; Roy Taylor; Sangil Lee; Armistead Russell; Karsten Baumann

2007-01-01

135

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

136

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

137

Identification and detection of oil and oil-derived substances at the surface and subsurface levels via hyperspectral imaging  

NASA Astrophysics Data System (ADS)

Detection and estimation of oil and oil-derived substances from an oil spill is a challenging issue. Over the last few years, several algorithms have been proposed for the detection of oil on the ocean surface. These techniques do not address the issue of detection of subsurface oil and estimate the depth of the location of oil at the subsurface level. In this paper, algorithms are developed to detect the presence of surface oil in ocean water using hyperspectral imagery. A support vector machine classifier was trained using region-of-interests (ROIs) to classify the oil/oil-derived substances under the water surface in the Gulf of Mexico. Using the pixel intensity of the identified oil based image, Beer-Lambert's law is used to calculate the depth at which the oil and/or oil-derived substance are present in the scene of investigation.

Alam, M. S.; Gollapalli, R. P.; Sidike, P.

2012-04-01

138

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

139

Deriving Texture Feature Set for Content-Based Retrieval of Satellite Image Database  

Microsoft Academic Search

In this paper, the performance of similarity retrieval from satellite image databases by using different sets of spatial and transformed-based texture features is evaluated and compared. A benchmark consisting of 37 satellite image clips from various satellite instruments is devised for the experiments. We show that although the proposed feature set perform only slightly better with the Brodatz set, its

Chung-sheng Li; Vittorio Clastelli

1997-01-01

140

PET image reconstruction with system matrix based on point spread function derived from single photon incidence response  

E-print Network

In positron emission tomography (PET) imaging, statistical iterative reconstruction (IR) techniques appear particularly promising since they can provide accurate physical model and geometric system description. The reconstructed image quality mainly depends on the system matrix model which describes the relationship between image space and projection space for the IR method. The system matrix can contain some physics factors of detection such as geometrical component and blurring component. Point spread function (PSF) is generally used to describe the blurring component. This paper proposes an IR method based on the PSF system matrix, which is derived from the single photon incidence response function. More specifically, the gamma photon incidence on a crystal array is simulated by the Monte Carlo (MC) simulation, and then the single photon incidence response functions are obtained. Subsequently, using the single photon incidence response functions, the coincidence blurring factor is acquired according to the...

Xin, Fan; Ming-Kai, Yun; Xiao-Li, Sun; Xue-Xiang, Cao; Shuang-Quanm, Liu; Pei, Chai; Dao-Wu, Li; Long, Wei

2014-01-01

141

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. PMID:21234108

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

2011-01-01

142

High input impedance amplifier  

NASA Technical Reports Server (NTRS)

High input impedance amplifiers are provided which reduce the input impedance solely to a capacitive reactance, or, in a somewhat more complex design, provide an extremely high essentially infinite, capacitive reactance. In one embodiment, where the input impedance is reduced in essence, to solely a capacitive reactance, an operational amplifier in a follower configuration is driven at its non-inverting input and a resistor with a predetermined magnitude is connected between the inverting and non-inverting inputs. A second embodiment eliminates the capacitance from the input by adding a second stage to the first embodiment. The second stage is a second operational amplifier in a non-inverting gain-stage configuration where the output of the first follower stage drives the non-inverting input of the second stage and the output of the second stage is fed back to the non-inverting input of the first stage through a capacitor of a predetermined magnitude. These amplifiers, while generally useful, are very useful as sensor buffer amplifiers that may eliminate significant sources of error.

Kleinberg, Leonard L.

1995-01-01

143

MDS MIC Catalog Inputs  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the inputs to the MDS Medical Information Communique (MIC) catalog. The purpose of the group is to provide input for updating the MDS MIC Catalog and to request that MMOP assign Action Item to other working groups and FSs to support the MITWG Process for developing MIC-DDs.

Johnson-Throop, Kathy A.; Vowell, C. W.; Smith, Byron; Darcy, Jeannette

2006-01-01

144

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

145

Comparison of NMR simulations of porous media derived from analytical and voxelized representations  

E-print Network

Comparison of NMR simulations of porous media derived from analytical and voxelized representations contained in various models of porous media. The grain-based approach uses a spherical grain pack as input, the input is a com- puter-tomography or computer-generated image of reconstructed porous media

Torres-Verdín, Carlos

146

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. PMID:24058519

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

2013-01-01

147

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 18F-Fluorodeoxyglucose (FDG) and 15O-Water (H2O). 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 H2O 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 H2O are obtained. PMID:24770914

Huang, Jian; O'Sullivan, Finbarr

2014-05-01

148

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

149

On the camparability of cloud fractions derived from whole sky imager and ceilometer data  

SciTech Connect

The Atmospheric Radiation Measurement (ARM) Program`s most heavily instrumented site is its central facility in Lamont, OK. With respect to cloud observations, the instrumentation included a whole sky imager, ceilometers, lidar, millimeter cloud radar, microwave profilers, and radiosondes. Data from three of these instrument--the Whole Sky Imager (WSI), Belfort Laser Ceilometer (BLC) and Micropulse Lidar (MPL)-- are used in this study primarily to investigate the utility of using ceilometers, now strategically emplaced at four additional locations along the perimeter of the site.

Rodriguez, D.

1998-01-30

150

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

151

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

PubMed Central

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. PMID:25302010

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

2014-01-01

152

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

153

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

154

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

155

Error Analysis of Spectral ReflectanceDerived from Imaging SpectrometerData' John P. Kerekes  

E-print Network

resulting from multiple scattering, as in a forest, are not considered. ILLUMINATION AND ATMOSPHERICEFFECTS significant paths for the radiance measured by an airbome or spacebome imaging spectrometer for a flat, nearly,vertical relief, or manmade objects. Four significant terms are seen to form the total radiance incident

Kerekes, John

156

DERIVING 3-D SHORELINES FROM HIGH RESOLUTION IKONOS SATELLITE IMAGES WITH RATIONAL FUNCTIONS  

Microsoft Academic Search

Rational Functions (RFs) have been used in the remote sensing community to replace the rigorous sensor models that are sometimes confidential or used to achieve a greater processing speed. In particular, they are used to define the imaging geometry for the data from emerging high-resolution satellites, allowing vendors to keep the sensor models confidential. This paper presents methods for and

Kaichang Di; Ruijin Ma; Ron Li

2001-01-01

157

Deriving statistical significance maps for support vector regression using medical imaging data  

PubMed Central

Regression analysis involves predicting a continuous variable using imaging data. The Support Vector Regression (SVR) algorithm has previously been used in addressing regression analysis in neuroimaging. However, identifying the regions of the image that the SVR uses to model the dependence of a target variable remains an open problem. It is an important issue when one wants to biologically interpret the meaning of a pattern that predicts the variable(s) of interest, and therefore to understand normal or pathological process. One possible approach to the identification of these regions is the use of permutation testing. Permutation testing involves 1) generation of a large set of ‘null SVR models’ using randomly permuted sets of target variables, and 2) comparison of the SVR model trained using the original labels to the set of null models. These permutation tests often require prohibitively long computational time. Recent work in support vector classification shows that it is possible to analytically approximate the results of permutation testing in medical image analysis. We propose an analogous approach to approximate permutation testing based analysis for support vector regression with medical imaging data. In this paper we present 1) the theory behind our approximation, and 2) experimental results using two real datasets.

Gaonkar, Bilwaj; Sotiras, Aristeidis; Davatzikos, Christos

2013-01-01

158

Radiolabeled Mannosylated Dextran Derivatives Bearing an NIR-Fluorophore for Sentinel Lymph Node Imaging.  

PubMed

Current methods for sentinel lymph node (SLN) mapping involve the use of radioactivity detection with technetium-99m sulfur colloid and/or visually guided identification using a blue dye. To overcome the kinetic variations of two individual imaging agents through the lymphatic system, we report herein on two multifunctional macromolecules, 5a and 6a, that contain a radionuclide ((99m)Tc or (68)Ga) and a near-infrared (NIR) reporter for pre- and/or intraoperative SLN mapping by nuclear and NIR optical imaging techniques. Both bimodal probes are dextran-based polymers (10 kDa) functionalized with pyrazole-diamine (Pz) or 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelating units for labeling with fac-[(99m)Tc(CO)3](+) or (68)Ga(III), respectively, mannose units for receptor targeting, and NIR fluorophore units for optical imaging. The probes allowed a clear visualization of the popliteal node by single-photon emission computed tomography (SPECT/CT) or positron emission tomography (PET/CT), as well as real-time optically guided excision. Biodistribution studies confirmed that both macromolecules present a significant accumulation in the popliteal node (5a: 3.87 ± 0.63% IA/organ; 6a: 1.04 ± 0.26% IA/organ), with minimal spread to other organs. The multifunctional nanoplatforms display a popliteal extraction efficiency >90%, highlighting their potential to be further explored as dual imaging agents. PMID:25265437

Morais, Maurício; Campello, Maria P C; Xavier, Catarina; Heemskerk, Johannes; Correia, João D G; Lahoutte, Tony; Caveliers, Vicky; Hernot, Sophie; Santos, Isabel

2014-11-19

159

Speckle image analysis of cortical blood flow and perfusion using temporally derived contrasts  

Microsoft Academic Search

Contrast values estimated from temporal statistics is used for laser speckle contrast analysis (LASCA) of cortical blood flow and perfusion. Using temporal statistics, we are able to reliably estimate the blood flow and perfusion by processing only a selected number of pixels from the raw speckle images. For the number of frames (N > 6) for estimating the temporal contrast,

Allan Tan; Wanzhen Liu; Yan Seng Elijah Yew; Sim Heng Ong; Joseph Suresh Paul

2004-01-01

160

Localized regulatory frequencies of human skin temperature derived from the analysis of series of infrared images  

Microsoft Academic Search

The physiological function of human skin in body temperature regulation is reviewed, and methods for measuring skin temperature are described. Different ways to extract diagnostic data from thermal images, focusing on dynamic studies that provide valuable information on the physiological and pathological functions of the autonomous nervous system, are presented. Using fast-Fourier-transform analysis, the frequencies of the different regulatory processes

Michael Anbar; Sean D'Arcy

1991-01-01

161

Picture-based physics: Using POD derived process constraints to enhance imaging of groundwater systems  

NASA Astrophysics Data System (ADS)

Geophysical imaging techniques are increasingly important tools for developing conceptual models of subsurface processes and characterizing hydrogeologic properties. In particular, recent studies have shown that coupled inversion, i.e., using coupled hydrologic process and geophysical instrument simulators as a single forward model, can lead to vast improvements in our ability to accurately constrain estimates of aquifer hydraulic properties with a limited amount of geophysical data. In this case, the hydrologic model acts as an implicit process constraint that regularizes the inverse problem. A major challenge with the coupled approach, however, is that the hydrologic process model is a hard constraint on the inverse problem; it is not possible to accurately reproduce subsurface behaviors when the conceptualization of the hydrologic model is incorrect. To overcome this issue, we take an image-processing perspective to develop physics-based constraints for inverse problems. Philosophically our approach is analogous to the use of images as training data for inferring multiple point geostatistics. In our case, however, we instead use training images to extract a set of basis vectors using proper orthogonal decomposition (POD) that can be used to constrain the inverse problem. Careful selection of a basis for an inverse problem is important as an appropriate basis can significantly improve estimation efficiency and accuracy. A key element of our approach is that the training images are generated using Monte Carlo simulations of the physical groundwater process of interest (e.g., flow and transport). As a result the training images and POD basis provide a site specific, non-parametric representation of the processes driving the groundwater system. A consequence is that a limited number of POD basis vectors can be used to compactly capture complex heterogeneities within the subsurface, thereby reducing the dimensionality of parameter space and effectively regularizing the inverse problem. In this talk we provide a conceptual understanding of POD and its application to inverse problems. We then provide examples where the POD inversion strategy is used to enhance geophysical imaging of unsaturated flow in the vadose zone and solute transport in an aquifer. Finally, we discuss how the POD approach can be extended for applications such as hydraulic tomography and general geostatistical estimation problems.

Moysey, S. M.; Oware, E. K.; Khan, T.

2012-12-01

162

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

PubMed

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. PMID:24113375

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

163

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

164

Water-soluble derivatives of chitosan as a target delivery system of 99m Tc to some organs in vivo for nuclear imaging and biodistribution  

Microsoft Academic Search

Carboxymethyl chitosan, (CMC), and N-lauryl-carboxymethyl chitosan (LCMC), have been prepared as water soluble derivatives of chitosan. These biodegradable chitosan\\u000a derivatives were characterized and investigated for nuclear imaging and body distribution. They were labeled with 99mTc to use them as targeted delivery to some organs in vivo for nuclear imaging and to follow their biodistribution within\\u000a the body. The factors controlling

Dalia L. Hawary; Mohamed A. Motaleb; Hamed Farag; Osiris W. Guirguis; Maher Z. Elsabee

165

Preparation and evaluation of technetium-99m labeled cardiac glycoside derivatives as potential myocardial imaging agent.  

PubMed

Three cardiac glycosides, two natural, cymarin and convallotoxin and one synthetic, strophanthidin-beta-D-glucoside were converted to their thiosemicarbazone and subsequently radiolabeled with 99mTc by chelation. The resulting radioactive chelate complexes were evaluated in animals to determine the suitability of this class of compounds for myocardial imaging. It was observed from the animal biodistribution data of the three radioactive compounds, there was a considerable variation in the heart to non-target organ uptake ratio. A possible explanation of this variation was offered in the light of their lipophilic character, protein binding ability and affinity towards non-target receptors. It is anticipated that this study may help to develop a 99mTc-cardiac glycoside complex with better distribution characteristics, and such a compound may offer a suitable alternative to 201Tl, which is at present used for myocardial imaging. PMID:3255737

Misra, M; Sarkar, H S; Chatterjee, M; Banerjee, S

1988-01-01

166

Atomic force and scanning tunneling microscopy imaging of graphene nanosheets derived from graphite oxide.  

PubMed

Graphene nanosheets produced in the form of stable aqueous dispersions by chemical reduction of graphene oxide and deposited onto graphite substrates have been investigated by atomic force and scanning tunneling microscopy (AFM/STM). The chemically reduced graphene oxide nanosheets were hardly distinguishable from their unreduced counterparts in the topographic AFM images. However, they could be readily discriminated through phase imaging in the attractive regime of tapping-mode AFM, probably because of differences in hydrophilicity arising from their distinct oxygen contents. The chemically reduced nanosheets displayed a smoothly undulated, globular morphology on the nanometer scale, with typical vertical variations in the subnanometer range and lateral feature sizes of approximately 5-10 nm. Such morphology was attributed to be the result of significant structural disorder in the carbon skeleton, which originates during the strong oxidation that leads to graphene oxide and remains after chemical reduction. Direct evidence of structural disorder was provided by atomic-scale STM imaging, which revealed an absence of long-range periodicity in the graphene nanosheets. Only structured domains a few nanometers large were observed instead. Likewise, the nanosheet edges appeared atomically rough and ill-defined, though smooth on the nanometer scale. The unreduced graphene oxide nanosheets could only be imaged by STM at very low tunneling currents (approximately 1 pA), being visualized in some cases with inverted contrast relative to the graphite substrate, a result that was attributed to their extremely low conductivity. Complementary characterization of the unreduced and chemically reduced nanosheets was carried out by thermogravimetric analysis as well as UV-visible absorption and X-ray photoelectron and Raman spectroscopies. In particular, the somewhat puzzling Raman results were interpreted to be the result of an amorphous character of the graphene oxide material. PMID:19341286

Paredes, J I; Villar-Rodil, S; Solís-Fernández, P; Martínez-Alonso, A; Tascón, J M D

2009-05-19

167

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

168

Correlation between MR imaging-derived nasopharyngeal carcinoma tumor volume and TNM system  

SciTech Connect

Purpose: To measure nasopharyngeal carcinoma tumor volume based on magnetic resonance images using a validated semiautomated measurement methodology and correlate tumor volume with TNM T classification. Methods and Materials: The study population consisted of 206 consecutive nasopharyngeal carcinoma patients who had magnetic resonance imaging staging scans. Tumor volume was measured using a semisupervised knowledge-based fuzzy clustering algorithm. Patients were divided into 4 groups according to TNM T classification. The difference in tumor volumes among the various TNM T-classification groups was examined. Results: The mean tumor volume in each T-classification group is as follows: T1, 8.6 mL {+-} 5.0 (standard deviation [SD]); T2, 18.1 mL {+-} 8.1 (SD); T3, 25.8 mL {+-} 14.1 (SD); and T4, 36.2 mL {+-} 18.9 (SD). The mean tumor volume increased significantly with advancing T classification (p < 0.0001). Tumor volume in a more advanced T group was significantly larger than that in an adjacent early T group (p < 0.01). Conclusion: Validated magnetic resonance imaging-based tumor volume shows positive correlation between tumor volume and advancing T-classification groups. It may be possible to incorporate tumor volume as an additional prognostic factor into the existing TNM system.

Chong, Vincent F.H. [Department of Diagnostic Radiology, Faculty of Medicine, National University of Singapore, Singapore (Singapore)]. E-mail: dnrcfhv@nus.edu.sg; Zhou, J.-Y. [Biomedical Engineering Research Centre, Nanyang Technological University, Singapore (Singapore); Khoo, James B.K. [Department of Oncologic Imaging, National Cancer Centre, Singapore (Singapore); Chan, K.-L. [Biomedical Engineering Research Centre, Nanyang Technological University, Singapore (Singapore); Huang Jing [Department of Oncologic Imaging, National Cancer Centre, Singapore (Singapore)

2006-01-01

169

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

170

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

171

Elastic and transport properties of cellular solids derived from three-dimensional tomographic images  

NASA Astrophysics Data System (ADS)

We describe a three-dimensional imaging and analysis study of eight industrial cellular foam morphologies. The foam morphologies were generated by differing industrial processing methods. Tomograms are acquired on an X-ray micro-computed tomography facility at scales of approximately equal to (5mm)3 at resolutions down to 7?m. The image quality is sufficient in all cases to measure local structure and connectivity of the foamed material, and the field of view large enough to calculate a range of material properties. Phase separation into solid and porous components is straightforward.Three-dimensional structural characteristics are measured directly on the porous and solid phases of the images. A number of morphological parameters are obtained, including pore volume-to-surface-area ratio, connectivity, the pore and solid phase size distributions defined by maximal sphere openings and chord length measurements. We further calculate the pore size distribution associated with capillary pressure via simulating of mercury drainage on the digital images.The binarized microstructures are used as a basis for calculations of transport properties (fluid permeability, diffusivity and thermal conductivity) and elastic moduli. From the data, we generate property-porosity relationships for the range of foam morphologies imaged and quantitatively analyse the effects of porosity and microstructure on the resultant properties of the foams.We compare our numerical data to commonly used theoretical and empirical property-porosity relationships. For thermal conductivity, we find that the numerical results agree extremely well with an empirical expression based on experimental data of various foams. The upper Hashin-Shtrikman bound also provides an excellent prediction of the data across all densities. From simulation of the diffusivity, we can define the tortuosity of the pore space within the cellular solid. We find that different processing methods lead to strong variations in the tortuosity of the pore space of the foams. For elastic properties, our results show that for the Young modulus, E, both the differential effective medium theory and the classical correlation E/Es=(?/?s)2 give a good correlation. Assuming a constant Poisson's ratio ? leads to reasonable agreement. The best correlation for ? is given by assuming a slight variation in ? as a linear function of porosity. The permeability of the foams varies over three orders of magnitude. Correlations for permeability based on the classical Kozeny-Carman equation lead to reasonable agreement, except at the lowest porosities. Permeability estimations based on mercury porosimetry give excellent agreement for all foams.

Knackstedt, Mark A.; Arns, Christoph H.; Saadatfar, Mohammad; et al.

2006-09-01

172

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. PMID:23255420

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

173

Synthesis of 68Ga-labeled DOTA-nitroimidazole derivatives and their feasibilities as hypoxia imaging PET tracers.  

PubMed

The imaging of hypoxia is important for therapeutic decision making in various diseases. (68)Ga is an important radionuclide for positron emission tomography (PET), and its usage is increasing, due to the development of the (68)Ge/(68)Ga-generator. In the present study, the authors synthesized two nitroimidazole derivatives by conjugating nitroimidazole and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) via an amide bond (4) and a thiourea bond (5). Both derivatives were labeled with (68)Ga with high labeling efficiency and were stable after labeling. The low partition coefficients (logP) of (68)Ga-4 (-4.6) and (68)Ga-5 (-4.5) demonstrated the hydrophilic natures of the derivatives, and both showed higher uptake in cancer cell lines cultured under hypoxic condition than under normoxic condition. However, (68)Ga-5 showed higher liver uptake than (68)Ga-4 in a biodistribution study due to higher lipophilicity. In an animal PET study, (68)Ga-4 showed higher standard uptake values (SUV) in tumors than (68)Ga-5 in mice xenografted with CT-26 mouse colon cancer cells. PMID:21419635

Hoigebazar, Lathika; Jeong, Jae Min; Hong, Mee Kyung; Kim, Young Ju; Lee, Ji Youn; Shetty, Dinesh; Lee, Yun-Sang; Lee, Dong Soo; Chung, June-Key; Lee, Myung Chul

2011-04-01

174

Comparison of biokinetics and biliary imaging parameters of four /sup 99m/Tc iminodiacetic acid derivatives in normal subjects  

SciTech Connect

The biokinetics (blood clearance, urinary excretion, hepatic peak time, uptake, and excretion t-1/2) and the imaging parameters (the time of appearance of the common bile duct, gallbladder, and duodenum) were determined in 34 normal subjects using /sup 99m/Tc diethyl (EIDA), /sup 99m/Tc dimethyl (HIDA), /sup 99m/Tc paraisopropyl (PIPIDA), and /sup 99m/Tc parabutyl (PBIDA) iminodiacetic acid derivatives. The blood and hepatic clearance of the four agents were significantly different (P less than 0.05) from each other. The 24-hour urinary excretion of PBIDA was significantly lower (P less than 0.05) than the urinary excretion of the other three agents. There was no difference among the four agents in the time of appearance of the gallbladder and duodenum. The time of appearance of the common bile duct was significantly delayed with PBIDA. The maximum intensity of the common bile duct usually occurred between 20 to 40 minutes with all four agents. However, gallbladder intensity continued to increase up to 3 hours. It is concluded that in the presence of normal liver function, all four /sup 99m/Tc IDA agents show definite differences in biokinetics but these differences do not have a major effect on biliary imaging parameters. If imaging alone is the primary goal, the selection of any one of the four agents will meet the clinican's need satisfactorily.

Bobba, V.V.; Krishnamurthy, G.T.; Kingston, E.; Brown, P.H.; Eklem, M.; Turner, F.E.

1983-02-01

175

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

176

N/2 Input Benes Network N/2 Input Benes Network  

E-print Network

(Top) N/2 Input Benes Network (Bottom) Figure 1: Structure of an N input Benes Network CS 606 Oine Network A Benes Network is simply a Butter y network on N inputs (denoted BN) connected \\in series" following a reverse butter y network on N inputs (denoted BH N). In particular, the node in row i column n

Ranade, Abhiram G.

177

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

178

Scaling, propagating and mapping uncertainty in spectroscopy-derived foliar traits from the leaf to the image  

NASA Astrophysics Data System (ADS)

A major goal of remote sensing, and imaging spectroscopy in particular, is the development of generalizable algorithms to repeatedly and accurately map ecosystem properties such as canopy chemistry across space and time. Existing methods must therefore be tested across a range of measurement approaches to identify and overcome limits to the consistent retrieval of such properties from spectroscopic imagery. Here we illustrate a general approach for the estimation of key foliar biochemical and morphological traits from spectroscopic imagery derived from the AVIRIS instrument and the propagation of errors from the leaf to the image scale using partial least squares regression (PLSR) techniques. Our method involves the integration of three types of data representing different scales of observation: At the image scale, the images were normalized for atmospheric, illumination and BRDF effects. Spectra from field plot locations were extracted from the 51AVIRIS images and were averaged when the field plot was larger than a single pixel. At the plot level, the scaling was conducted using multiple replicates (1000) derived from the leaf-level uncertainty estimates to generate plot-level estimates with their associated uncertainties. Leaf-level estimates of foliar traits (%N, %C, %Fiber, %Cellulose, %Lignin, LMA) were scaled to the canopy based on relative species composition of each plot. Image spectra were iteratively split into 50/50 randomized calibration-validation datasets and multiple (500) trait-predictive PLSR models were generated, this time sampling from within the plot-level uncertainty distribution. This allowed the propagation of uncertainty from the leaf-level dependent variables to the plot level, and finally to models built using AVIRIS image spectra. Moreover, this method allows us to generate spatially explicit maps of uncertainty in our sampled traits. Both LMA and %N PLSR models had a R2 greater than 0.8, root mean square errors (RMSEs) for both variables were less than 6% of the range of data. Fiber and lignin were predicted with R2 > 0.65 and carbon and cellulose greater than 0.5. Although R2 of these variables were lower than LMA and %N, their RMSE values were beneath 9% of the range of data. The comparatively lower R2 values for %C and cellulose in particular were related to the low amount of natural variability in these constituents. Further, coefficients from the randomized set of PLSR models were applied to imagery and aggregated to obtain pixel-wise predicted means and uncertainty estimates for each foliar trait. The resulting maps of nutritional and morphological properties together with their overall uncertainties represent a first-of-its-kind data product for examining the spatio-temporal patterns of forest functioning and nutrient cycling. These data are now being used to relate foliar traits with ecosystem processes such as streamwater nutrient export and insect herbivory. In addition, the ability to assign a retrieval uncertainty enables more efficient assimilation of these data products into ecosystem models to help constrain carbon and nutrient cycling projections.

Singh, A.; Serbin, S. P.; Kingdon, C.; Townsend, P. A.

2013-12-01

179

Approach to derivation of SIR-C science requirements for calibration. [Shuttle Imaging Radar  

NASA Technical Reports Server (NTRS)

Many of the experiments proposed for the forthcoming SIR-C mission require calibrated data, for example those which emphasize (1) deriving quantitative geophysical information (e.g., surface roughness and dielectric constant), (2) monitoring daily and seasonal changes in the Earth's surface (e.g., soil moisture), (3) extending local case studies to regional and worldwide scales, and (4) using SIR-C data with other spaceborne sensors (e.g., ERS-1, JERS-1, and Radarsat). There are three different aspects to the SIR-C calibration problem: radiometric and geometric calibration, which have been previously reported, and polarimetric calibration. The study described in this paper is an attempt at determining the science requirements for polarimetric calibration for SIR-C. A model describing the effect of miscalibration is presented first, followed by an example describing how to assess the calibration requirements specific to an experiment. The effects of miscalibration on some commonly used polarimetric parameters are also discussed. It is shown that polarimetric calibration requirements are strongly application dependent. In consequence, the SIR-C investigators are advised to assess the calibration requirements of their own experiment. A set of numbers summarizing SIR-C polarimetric calibration goals concludes this paper.

Dubois, Pascale C.; Evans, Diane; Van Zyl, Jakob

1992-01-01

180

Integration of Image Data for Refining Building Boundaries Derived from Point Clouds  

NASA Astrophysics Data System (ADS)

Geometrically and topologically correct 3D building models are required to satisfy with new demands such as 3D cadastre, map updating, and decision making. More attention on building reconstruction has been paid using Airborne Laser Scanning (ALS) point cloud data. The planimetric accuracy of roof outlines, including step-edges is questionable in building models derived from only point clouds. This paper presents a new approach for the detection of accurate building boundaries by merging point clouds acquired by ALS and aerial photographs. It comprises two major parts: reconstruction of initial roof models from point clouds only, and refinement of their boundaries. A shortest closed circle (graph) analysis method is employed to generate building models in the first step. Having the advantages of high reliability, this method provides reconstruction without prior knowledge of primitive building types even when complex height jumps and various types of building roof are available. The accurate position of boundaries of the initial models is determined by the integration of the edges extracted from aerial photographs. In this process, scene constraints defined based on the initial roof models are introduced as the initial roof models are representing explicit unambiguous geometries about the scene. Experiments were conducted using the ISPRS benchmark test data. Based on test results, we show that the proposed approach can reconstruct 3D building models with higher geometrical (planimetry and vertical) and topological accuracy.

Perera, S. N.; Hetti Arachchige, N.; Schneider, D.

2014-08-01

181

Monitoring tropical-cyclone intensity using environmental wind fields derived from short-interval satellite images  

NASA Technical Reports Server (NTRS)

The feasibility of predicting changes in tropical storm intensity based on satellite observations of the dynamical relationships between the large-scale upper and lower tropospheric circulations surrounding the cyclone and the characteristics of the storm's inner core is studied. Rapid-scan visible images from the SMS-1 and GOES-1 satellites were used to examine the local change in relative angular momentum (RAM), the lower and upper tropospheric environmental areal mean relative vorticity and transverse circulation on three consecutive days for tropical storms Caroline (August, 1975), Anita (August and September, 1977) and Ella (September, 1978). The three case studies suggest that storm intensification may be predicted from the storm's local change of net RAM, with this quantity best correlated with storm intensification after a time lag of 6 hours. Intensification is also found to be related to the environmental lower and upper tropospheric areal-mean relative vorticity, and to the upper tropospheric environmental circulation, which acts either to hinder or to enhance the storm's anticyclonic outflow channels.

Rodgers, E.; Gentry, R. C.

1983-01-01

182

Visualization of Membrane Rafts Using a Perylene Monoimide Derivative and Fluorescence Lifetime Imaging  

PubMed Central

A new membrane probe, based on the perylene imide chromophore, with excellent photophysical properties (high absorption coefficient, quantum yield (QY) ? 1, high photostability) and excited in the visible domain is proposed for the study of membrane rafts. Visualization of separation between the liquid-ordered (Lo) and the liquid-disordered (Ld) phases can be achieved in artificial membranes by fluorescence lifetime imaging due to the different decay times of the membrane probe in the two phases. Rafts on micrometer-scale in cell membranes due to cellular activation can also be observed by this method. The decay time of the dye in the Lo phase is higher than in organic solvents where its QY is 1. This allows proposing a (possible general) mechanism for the decay time increase in the Lo phase, based on the local field effects of the surrounding molecules. For other fluorophores with QY < 1, the suggested mechanism could also contribute, in addition to effects reducing the nonradiative decay pathways, to an increase of the fluorescence decay time in the Lo phase. PMID:17573424

Margineanu, Anca; Hotta, Jun-ichi; Van der Auweraer, Mark; Ameloot, Marcel; Stefan, Alina; Beljonne, David; Engelborghs, Yves; Herrmann, Andreas; Mullen, Klaus; De Schryver, Frans C.; Hofkens, Johan

2007-01-01

183

Lanthanide (III) complexes of PCTA-(tris-amide) derivatives as potential bimodal MRI and optical imaging agents  

PubMed Central

Lanthanide complexes of two tris-(amide) derivatives of PCTA were synthesized and characterized. The relaxometric and luminescence properties of their lanthanide complexes were investigated as bimodal magnetic resonance (MR) and optical imaging agents. Luminescence studies show that one of the TbIII complexes dimerizes in solution at low millimolar concentrations while the other may have a higher than expected coordination number in solution. The corresponding GdIII complexes display unusually high T1 relaxivities and enhanced kinetic inertness compared to GdPCTA. These features suggest that these new chelates may be suitable for in vivo applications. The fast water exchange rates observed for these complexes make them unsuitable as paramagnetic chemical exchange saturation transfer (PARACEST) agents. PMID:19882595

Rojas-Quijano, Federico A.; Benyo, Eniko Tircsone; Tircso, Gyula; Kalman, Ferenc K.; Baranyai, Zsolt; Aime, Silvio; Sherry, A. Dean

2010-01-01

184

Multimodality Molecular Imaging of [18F]-Fluorinated Carboplatin Derivative Encapsulated in [111In]-Labeled Liposomes  

NASA Astrophysics Data System (ADS)

Platinum based chemotherapy is amongst the mainstream DNA-damaging agents used in clinical cancer therapy today. Agents such as cisplatin, carboplatin are clinically prescribed for the treatment of solid tumors either as single agents, in combination, or as part of multi-modality treatment strategy. Despite the potent anti-tumor activity of these drugs, overall effectiveness is still hampered by inadequate delivery and retention of drug in tumor and unwanted normal tissue toxicity, induced by non-selective accumulation of drug in normal cells and tissues. Utilizing molecular imaging and nanoparticle technologies, this thesis aims to contribute to better understanding of how to improve the profile of platinum based therapy. By developing a novel fluorinated derivative of carboplatin, incorporating a Flourine-18 (18F) moiety as an inherent part of the molecule, quantitative measures of drug concentration in tumors and normal tissues can be directly determined in vivo and within the intact individual environment. A potential impact of this knowledge will be helpful in predicting the overall response of individual patients to the treatment. Specifically, the aim of this project, therefore, is the development of a fluorinated carboplatin drug derivative with an inherent positron emission tomography (PET) imaging capability, so that the accumulation of the drug in the tumor and normal organs can be studied during the course of therapy . A secondary objective of this research is to develop a proof of concept for simultaneous imaging of a PET radiolabeled drug with a SPECT radiolabeled liposomal formulation, enabling thereby bi-modal imaging of drug and delivery vehicle in vivo. The approach is challenging because it involves development in PET radiochemistry, PET and SPECT imaging, drug liposomal encapsulation, and a dual-modal imaging of radiolabeled drug and radiolabeled vehicle. The principal development is the synthesis of fluorinated carboplatin 19F-FCP using 2-(5-fluoro-pentyl)-2-methyl malonic acid as the labeling agent to coordinate with the cisplatin aqua complex. It was then used to treat various cell lines and compared with cisplatin and carboplatin at different concentrations ranging from 0.001 microM to 100 microM for 72 hrs and 96 hrs. IC50 values calculated from cell viability indicated that 19F-FCP is a more potent drug than Carboplatin. Manual radiosynthesis and characterization of [18F]-FCP was performed using [18F]-2-(5-fluoro-pentyl)-2-methyl malonic acid with coordination with cisplatin aqua complex. Automated radiosynthesis of [18F]-FCP was optimized using the manual synthetic procedures and using them as macros for the radiosynthesizer. [18F]-FCP was evaluated in vivo with detailed biodistribution studies and PET imaging in normal and KB 3-1 and KB 8-5 tumor xenograft bearing nude mice. The biodistribution studies and PET imaging of [18F]-FCP showed major uptake in kidneys which attributes to the renal clearance of radiotracer. In vivo plasma and urine stability demonstrated intact [18F]-FCP. [ 111In]-Labeled Liposomes was synthesized and physiochemical properties were assessed with DLS. [111In]-Labeled Liposome was evaluated in vivo with detailed pharmacokinetic studies and SPECT imaging. The biodistribution and ROI analysis from SPECT imaging showed the spleen and liver uptake of [111In]-Labeled Liposome and subsequent clearance of activity with time. [18F]-FCP encapsulated [111In]-Labeled Liposome was developed and physiochemical properties were characterized with DLS. [18F]-FCP encapsulated [111In]-Labeled Liposome was used for in vivo dual tracer PET and SPECT imaging from the same nanoconstruct in KB 3-1 (sensitive) and COLO 205 (resistant) tumor xenograft bearing nude mice. PET imaging of [18F]-FCP in KB 3-1 (sensitive) and COLO 205 (resistant) tumor xenograft bearing nude mice was performed. Naked [18F]-FCP and [18F]-FCP encapsulated [ 111In]-Labeled Liposome showed different pharmacokinetic profiles. PET imaging of [18F]-FCP showed major uptake in kidneys and bladder. However, [18F]-FCP encapsula

Lamichhane, Narottam

185

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

PubMed

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. PMID:24573178

Grange, Cristina; Tapparo, Marta; Bruno, Stefania; Chatterjee, Devasis; Quesenberry, Peter J; Tetta, Ciro; Camussi, Giovanni

2014-05-01

186

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

187

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

188

Chitosan Derivatives Cross-Linked with Iodinated 2,5-Dimethoxy-2,5-dihydrofuran for Non-Invasive Imaging.  

PubMed

Radiopaque polymer derivatives were successfully prepared through surface diffusion mediated cross-linking of chitosan with iodinated 2,5-dimethoxy-2,5-dihydrofuran. The incorporation of iodine in 2,5-dimethoxy-2,5-dihydrofuran was validated by (1)H NMR and mass spectroscopy. The cross-linking of the glucosamine moieties of chitosan with the iodinated product was confirmed by (13)C NMR and energy-dispersive X-ray spectroscopy. Radiography analysis proved inherent opacity of the iodinated fibrous sheets and microspheres that were comparable to the X-ray visibility of aluminum hollow rings of equivalent thickness and commercially available radiopaque tape, respectively. Microscopic studies evidenced retention of the fiber/microsphere morphology after the iodination/cross-linking reactions. The effects of iodination/cross-linking on the mechanical and biodegradation properties of fibers were studied by nanoindentation and enzymatic assay, respectively. In vitro and in vivo studies established the nontoxic, biodegradable nature of radiopaque derivatives. Iodinated fiber mesh implanted in a rabbit model was significantly X-ray opaque compared to the uncross-linked fiber mesh and medical grade surgical swabs. Further, opacity of the iodinated mesh was evident even after 60 days, though the intensity was reduced, which indicates the biodegradable nature of the iodinated polymer. The opacity of the iodinated sutures was also established in the computed tomography images. Finally, the sufficient in vivo contrast property of the radiopaque microspheres in the gastrointestinal tract indicates its possible role in clinical diagnostics. PMID:25265599

Ghosh, Paulomi; Das, Manisit; Rameshbabu, Arun Prabhu; Das, Dipankar; Datta, Sayanti; Pal, Sagar; Panda, Asit Baran; Dhara, Santanu

2014-10-22

189

Material input of Finnish foodstuffs  

Microsoft Academic Search

The Report introduces the material input of 23 Finnish foodstuff groups and Brazilian soy transported to Finland. Material input of the foodstuffs is present- ed using the MIPS-method (Material Input per Service unit). All the foodstuffs are studied using the same system boundaries. The material flows are counted towards the material input until the foodstuff is off the shelf. Shop-going,

Tommi Kauppinen; Satu Lähteenoja; Michael Lettenmeier

190

Coseismic Deformation from the 2008 Wenchuan, China, Earthquake Derived from ALOS/PALSAR Images  

NASA Astrophysics Data System (ADS)

We analyzed ALOS/PALSAR images along eight paths acquired before and after the mainshock of an earthquake in Wenchuan, in the Sichuan province of China, May 12, 2008. We found entire coseismic deformation features and detected many fringes in an approximately 100-km wide region surrounding the Longmen Shan fault zone. We found 6-7 broad elliptic fringes north of the epicenter, which indicated around 70-80-cm increase in range (distance between the ground and satellite). This pattern corresponded to subsidence or eastward shift of ground, which is often seen above the lower margin of a low-angled thrust. We also counted 8-9 fringes, i.e., 90-100-cm range decrease, between the fault zone and Chengdu. Chengdu is located roughly 50 km away from the Pengguan fault, which is the southernmost trace of the Longmen Shan fault zone. As this area is located on the footwall side, the pattern suggested a westward shift of the earth's surface. However, we could not obtain high correlations due to large displacements in the about 240 km long belt along the surface faults. Several concentric fringes were found along the Beichuan fault, which is the central trace of the Longmen Shan fault zone. This implied that the rupture process of this earthquake was complicated. We also performed pixel matching to estimate offsets in the region of low correlation. Positive and negative range offsets larger than 2 m were found on the north and south sides of the Beichuan fault, respectively. We observed a belt of negative range and azimuth offsets between the Beichuan and Pengguan faults. We calculated an interferogram using a multi-segment fault model with uniform slip along the Beichuan and Pengguan faults and estimated the slip distribution. Based on previous seismological studies, we assumed that the southwestern part dipped toward the northwest by 33 degrees, whereas the central and northeastern parts had a much steeper dip angle. We found two regions of slips larger than 4 m in the southwest and central parts of the Beichuan fault. The Pengguan segments may have much smaller slips (around 1 m). The southwestern segments of the Beichuan fault and the entire Pengguan fault had dominant thrust components, whereas dextral slip prevailed in the central and northeastern segments of the Beichuan fault. The estimated geodetic moment was 5.87 × 10 20Nm (Mw = 7.78).

Hashimoto, Manabu; Enomoto, Mari; Fukushima, Yo

2010-08-01

191

Multi-input/multi-output molecular response system based on the dynamic redox behavior of 3,3,4,4-tetraaryldihydro[5]helicene derivatives: reversible formation/destruction of chiral fluorophore and modulation of chiroptical properties by solvent polarity.  

PubMed

3,3,4,4-Tetaaryldihydro[5]helicenes (1) and 1,1'-binaphthyl-2,2'-diylbis(diarylcarbenium)s (2(2+)) can be reversibly interconverted upon electron transfer, which is accompanied by a vivid color change (electrochromism) as well as by the formation/cleavage of a C-C bond ("dynamic redox behavior"). Because only the neutral donor 1 exhibits strong fluorescence, electrochemical input can further modify the fluorescent properties of the pair. Due to the configurational stability of the helicity in 1 and axial chirality in 2(2+), the redox reaction of optically pure material proceeds stereospecifically, which induces a chiroptical change such as circular dichroism (CD) as an additional output. The CD spectra of dications 2(2+) exhibit solvent dependency (chiro-solvatochromism), which is accompanied by solvatochromic behavior based on the pi-pi interaction of the two cationic chromophores as well as coordinative interaction of the Lewis basic solvent to the Lewis acidic triarylcarbenium moieties. Thus, the present system is endowed with multi-input functionality for modifying multiple output signals. PMID:19621397

Suzuki, Takanori; Ishigaki, Yusuke; Iwai, Tomohiro; Kawai, Hidetoshi; Fujiwara, Kenshu; Ikeda, Hiroshi; Kano, Yusuke; Mizuno, Kazuhiko

2009-09-21

192

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

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

Spatial and temporal variability in Moderate Resolution Imaging Spectroradiometer-derived surface albedo over global arid regions  

NASA Astrophysics Data System (ADS)

We derive spectral and broadband surface albedo for global arid regions from data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra spacecraft, at 1 km spatial resolution for 2001. MODIS data show considerable spatial variability both across various arid regions of the globe (from the bright deserts of northern Africa and the Arabian peninsula to substantially less reflective American and Asian deserts) and within regions (variability related to soil and rock types). For example, over arid northern Africa and the Arabian peninsula, albedo in the visible broadband varies by a factor of over 2, from the brightest sand sheets to the darkest luvisols. Few, if any, global and regional land-atmosphere models capture this observed spatial variability in surface albedo over arid regions. We suggest a scheme that relates soil groups (based on the United Nations Food and Agriculture Organization (FAO) soil classification) to MODIS-derived surface albedo statistics. This approach allows for an efficient representation in climate and weather forecasting models of the observed spatial and temporal variability in surface albedo over global deserts. Observed variability in albedo was reduced to a small (1-13, depending on the region) number of soil-related classes (end-members) that could be used in climate models. We also addressed the temporal evolution of albedo during 2001 over global deserts. Regions/soils of stable albedo with very low temporal variability were identified. For other regions/soils, temporal signals in albedo were related to ephemeral inundation with water or variations in sample size.

Tsvetsinskaya, Elena A.; Schaaf, Crystal B.; Gao, Feng; Strahler, Alan H.; Dickinson, Robert E.

2006-10-01

195

Horizontal and vertical distribution of bromine monoxide in northern Alaska during BROMEX derived from airborne imaging-DOAS measurements  

NASA Astrophysics Data System (ADS)

Bromine monoxide (BrO) is a reactive halogen species (RHS) and has been known for quite a while to have a profound impact on the chemistry of the polar tropospheric boundary layer. Details of the bromine release and reaction processes are still unclear, especially the role of frost flowers, first-year sea ice, aerosols, atmospheric stability and snow. To investigate important details of the bromine release, a novel imaging DOAS instrument for the ultraviolet wavelength range (300 to 400 nm) was deployed aboard a light twin-engine aircraft (ALAR, Purdue Univ.) as part of the BRomine, Ozone, and Mercury EXperiment (BROMEX) in Barrow, Alaska, in spring 2012. This instrument utilizes (1) a scanner system in nadir direction to map trace gas distributions of the overflown area at high spatial resolution and (2) a forward-looking system, to observe the vertical trace gas distribution. Both viewing directions are equipped with digital cameras, enabling the creation of aerial maps and the comparison of spectral data with background features. We derived horizontal and vertical distribution of bromine monoxide (BrO) and other gases (e.g. NO2) over a wide variety of sea, ice and land surface conditions (first-year sea ice, frost flowers, open leads, and arctic tundra). We observed strong horizontal gradients of BrO within few km and a fast movement of BrO plumes. Distributions change significantly within few hours. The data show interesting correlations to the different surfaces. Additionally a clear anti-correlation of BrO and NO2 can be observed. Tropospheric BrO-distributions derived from satellite observations match within the satellite resolution those seen with the aircraft. Vertical gradients show a shallow layer of BrO close to the surface. These and other results from the 11 flights will be presented together with conclusions of the involved chemistry.

Pöhler, Denis; Stephan, General; Zielcke, Johannes; Shepson, Paul B.; Sihler, Holger; Stirm, Brian H.; Frieß, Udo; Pratt, Kerry A.; Walsh, Steve; Simpson, William R.; Platt, Ulrich

2013-04-01

196

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

197

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

198

A large area TDI image sensor for low light level imaging  

Microsoft Academic Search

A 1030 x 128 element time delay and integration (TDI) CCD image sensor has been developed for low-light-level (LLL) imaging applications. For LLL imaging, output is derived from a high-gain low-noise floating-gate amplifier (FGA). For larger input signal levels, a second, resettable floating-gate amplifier (RFGA) with lower gain and wider dynamic range provides output in parallel to the FGA. The

M. G. Farrier; R. H. Dyck

1980-01-01

199

Input Multiplicities in Process Control.  

ERIC Educational Resources Information Center

Describes research investigating potential effect of input multiplicity on multivariable chemical process control systems. Several simple processes are shown to exhibit the possibility of theoretical developments on input multiplicity and closely related phenomena are discussed. (JN)

Koppel, Lowell B.

1983-01-01

200

Identification of a Novel Indoline Derivative for in Vivo Fluorescent Imaging of Blood-Brain Barrier Disruption in Animal Models  

PubMed Central

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

2013-01-01

201

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

202

Automatic identification and delineation of germ layer components in H&E stained images of teratomas derived from human and nonhuman primate embryonic stem cells  

Microsoft Academic Search

We present a methodology for the automatic identification and delineation of germ-layer components in H&E stained images of teratomas derived from human and nonhuman primate embryonic stem cells. A knowledge and understanding of the biology of these cells may lead to advances in tissue regeneration and repair, the treatment of genetic and developmental syndromes, and drug testing and discovery. As

Ramamurthy Bhagavatula; Matthew C. Fickus; W. Kelly; Chenlei Guo; John A. Ozolek; Carlos A. Castro; Jelena Kovacevic

2010-01-01

203

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

204

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

205

Evaluation of Modified PEG-Anilinoquinazoline Derivatives as Potential Agents for EGFR Imaging in Cancer by Small Animal PET  

PubMed Central

Purpose The in vivo evaluation of three modified polyethylene glycol (PEG)-anilinoquinazoline derivatives labeled with 124I, 18F, and 11C as potential positron emission tomography (PET) bioprobes for visualizing epidermal growth factor receptor (EGFR) in cancer using small animal PET. Procedures Xenograft mice with the human glioblastoma cell lines U138MG (lacking EGFR expression) and U87MG.wtEGFR (transfected with an overexpressing human wild-type EGFR gene) were used. Static and dynamic PET imaging was conducted for all three PEGylated compounds. Tumor necrosis, microvessel density, and EGFR levels were evaluated by histopathology and enzyme-linked immunosorbent assay. Results Nineteen animal models were generated (two U138MG, three U87MG, 14 with both U138MG and U87MG bilateral masses). In static images, a slight increase in tracer uptake was observed in tumors, but in general, there was no retention of tracer uptake over time and no difference in uptake between U138MG and U87MG masses. In addition, no significant uptake was demonstrated in dynamic scans of the 18F-PEG tracer. No necrosis was present except in four animals. MVD was 9.6 and 48 microvessels/×400 field in the U138GM and U87GM masses, respectively (p?=?0.00008). Similarly, the microvessel grades were generally higher in the U87GM group (p?=?0.002). Total EGFR amount was higher in U87MG than U138MG masses (p?=?0.001), but the ratio of activated (pY1068) to total EGFR did not differ (p?=?0.95). Conclusions PEGylated tracers labeled with 11C, 124I, and 18F showed no significant difference in uptake between U138MG and U87MG glioblastoma xenograft mice. The tracer binding with EGFR could be influenced by activation of the tyrosine kinase portion of the receptor which was similar in U138MG and U87MG. Despite these results, these tracers should be investigated in animal models with mutant EGFR genes to determine whether aberrant receptor function plays a role in tumor uptake. PMID:20379787

Mishani, Eyal; Nanni, Cristina; Landuzzi, Lorena; Boschi, Stefano; Nicoletti, Giordano; Dissoki, Samar; Paterini, Paola; Piccaluga, Pier Poalo; Lodi, Filippo; Lollini, Pier-Luigi; Fanti, Stefano; Biasco, Guido

2010-01-01

206

SDR Input Power Estimation Algorithms  

NASA Technical Reports Server (NTRS)

The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) provides experimenters an opportunity to develop and demonstrate experimental waveforms in space. The SDR has an analog and a digital automatic gain control (AGC) and the response of the AGCs to changes in SDR input power and temperature was characterized prior to the launch and installation of the SCAN Testbed on the ISS. The AGCs were used to estimate the SDR input power and SNR of the received signal and the characterization results showed a nonlinear response to SDR input power and temperature. In order to estimate the SDR input from the AGCs, three algorithms were developed and implemented on the ground software of the SCAN Testbed. The algorithms include a linear straight line estimator, which used the digital AGC and the temperature to estimate the SDR input power over a narrower section of the SDR input power range. There is a linear adaptive filter algorithm that uses both AGCs and the temperature to estimate the SDR input power over a wide input power range. Finally, an algorithm that uses neural networks was designed to estimate the input power over a wide range. This paper describes the algorithms in detail and their associated performance in estimating the SDR input power.

Nappier, Jennifer M.; Briones, Janette C.

2013-01-01

207

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

208

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

209

Learning to represent visual input.  

PubMed

One of the central problems in computational neuroscience is to understand how the object-recognition pathway of the cortex learns a deep hierarchy of nonlinear feature detectors. Recent progress in machine learning shows that it is possible to learn deep hierarchies without requiring any labelled data. The feature detectors are learned one layer at a time and the goal of the learning procedure is to form a good generative model of images, not to predict the class of each image. The learning procedure only requires the pairwise correlations between the activations of neuron-like processing units in adjacent layers. The original version of the learning procedure is derived from a quadratic 'energy' function but it can be extended to allow third-order, multiplicative interactions in which neurons gate the pairwise interactions between other neurons. A technique for factoring the third-order interactions leads to a learning module that again has a simple learning rule based on pairwise correlations. This module looks remarkably like modules that have been proposed by both biologists trying to explain the responses of neurons and engineers trying to create systems that can recognize objects. PMID:20008395

Hinton, Geoffrey E

2010-01-12

210

Learning to represent visual input  

PubMed Central

One of the central problems in computational neuroscience is to understand how the object-recognition pathway of the cortex learns a deep hierarchy of nonlinear feature detectors. Recent progress in machine learning shows that it is possible to learn deep hierarchies without requiring any labelled data. The feature detectors are learned one layer at a time and the goal of the learning procedure is to form a good generative model of images, not to predict the class of each image. The learning procedure only requires the pairwise correlations between the activations of neuron-like processing units in adjacent layers. The original version of the learning procedure is derived from a quadratic ‘energy’ function but it can be extended to allow third-order, multiplicative interactions in which neurons gate the pairwise interactions between other neurons. A technique for factoring the third-order interactions leads to a learning module that again has a simple learning rule based on pairwise correlations. This module looks remarkably like modules that have been proposed by both biologists trying to explain the responses of neurons and engineers trying to create systems that can recognize objects. PMID:20008395

Hinton, Geoffrey E.

2010-01-01

211

Hierarchical image fusion  

Microsoft Academic Search

A hierarchical image fusion scheme is presented that preserves those details from the input images that are most relevant to visual perception. Results show that fused images present a more detailed representation of the scene and provide information that cannot be obtained by viewing the input images separately. Detection, recognition, and search tasks may therefore benefit from this fused image

Alexander Toet

1989-01-01

212

Inputs to the atmosphere from relativistic electrons  

SciTech Connect

The precipitation rates into the atmosphere of electrons >1 MeV during a weak relativistic enhancements in the spring of 1979 have been derived from electron fluxes measured on a low-altitude satellite, P78-1. The inputs to the atmosphere were obtained from drift loss cone fluxes of electrons >1 MeV by using measurements with fine angular resolution at lower energies of the ratios of the direct precipitation rates to the fluxes of locally trapped electrons. The analyses indicated that often the inputs to the atmosphere may be primarily from precipitating electrons at pitch angles near the edge of the trapped fluxes, illustrating the inadequacy of broad angular resolution measurements for precipitation studies. The data showed a strong L dependence for the precipitation of relativistic electrons extending from L {approx} 2.5 to L {approx} 8.5, indicating the limitations of obtaining inputs to the atmosphere from high-altitude measurements alone over a limited L shell range, such as at geosynchronous altitude (L {approx} 6.6). When summed over all longitudes and latitudes in the southern hemisphere, the total input energy rate of electrons >1 MeV precipitating into the atmosphere near the peak of the event on May 25-30, 1979, was {approximately}5 x 10{sup 19} ergs d{sup {minus}1}. 8 refs., 8 figs.

Imhof, W.L.; Gaines, E.E. [Lockheed Palo Alto Research Lab., CA (United States)

1993-08-01

213

Optimizing multiresolution pixel-level image fusion  

NASA Astrophysics Data System (ADS)

A number of pixel level image fusion schemes have been proposed in the past which combine registered input sensor images into a single fused output image. The two general objectives that underpin the operations of these schemes are a) the transfer of all visually important information form input images into a fused image and b) the minimization of undesirable distortions and artifacts which may be generated in the fused image. Fusion is usually achieved by i) the decomposition of input images into representations of their spectral bands and ii) a selection process which transfers information from input bands to yield the required representation of a single fused output image. Furthermore, decomposition is often based on multi-resolution pyramidal representations and the selection process operates on corresponding input image pyramidal levels using selection templates which focus on local spectral characteristics. The performance of such a multi-resolution pixel level image fusion system depends primarily on the actual decomposition and selection algorithms used. Thus for a given decomposition selection arrangement, fusion performance is dependent on the pyramid size (i.e. number of level) and template size. Pyramid and template sizes on the other hand greatly influence the system's computational complexity. This paper is concerned with the performance optimization/characterization of several multi- resolution image fusion schemes, in general and with performance/ complexity trade-offs in particular. Performance is measured using a subjectively meaningful, objective fusion metric which has been proposed recently by authors and which is based on the preservation of image edge information. Thus fusion systems based on derivatives of Gaussian low-pass pyramid and the Discrete Wavelet transform are examined and their performances versus decomposition/selection parameters are defined and compared. The performance/algorithmic complexity results presented for these multi-resolution fusion systems highlight clearly their strengths and weaknesses.

Petrovic, Vladimir S.; Xydeas, Costas S.

2001-03-01

214

Eyewear-style three-dimensional endoscope derived from microstructured polymer fiber with the function of image transmission  

NASA Astrophysics Data System (ADS)

A method of fabricating multi-core polymer image fiber is proposed. Image fiber preform is fabricated by stacking thousands of polymer fibers each with a 0.25-mm diameter orderly in a die by only one step. The preform is heated and stretched into image fiber with an outer diameter of 2 mm. Then a portable eyewear-style three-dimensional (3D) endoscope system is designed, fabricated, and characterized. This endoscopic system is composed of two graded index lenses, two pieces of 0.35-m length image guide fibers, and a pair of oculars. It shows good flexibility and portability, and can provide the depth information accordingly.

Kong, De-Peng; Wang, Li-Li; He, Zheng-Quan; Chu, Jiu-Rong; Ma, Tian

2013-02-01

215

Input a journal Viewing Journals  

E-print Network

Journals Contents: Input a journal Viewing Journals Deleting a journal Entering jnl into different period Problems Input a journal 1 Login to Bluqube 2 Select 3 Enter relevant Doc type To select the number of journals you will processing & the total credit value 6 Click on 7 Enter brief description 8

Sussex, University of

216

High-resolution three-dimensional imaging of the rich membrane structures of bone marrow-derived mast cells  

E-print Network

-derived mast cells T. Zink a , Z. Deng b , H. Chen c , L. Yu c , F.T. Liu c , G.Y. Liu a,b,Ã? a Biophysics marrow-derived mast cells. Cells were immobilized by a quick centrifugation and fixation to preserve of individual cells. & 2008 Elsevier B.V. All rights reserved. 1. Introduction Mast cells represent a class

Liu, Gang-yu

217

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

218

Correlation of Multiple Sclerosis Measures Derived from T2Weighted, T1Weighted, Magnetization Transfer, and Diffusion Tensor MR Imaging  

Microsoft Academic Search

BACKGROUND AND PURPOSE: In multiple sclerosis (MS), the severity of tissue damage can vary from edema and inflammation to irreversible demyelination and axonal loss. Com- pared with conventional T2-weighted MR imaging, magnetization transfer (MT) and diffusion tensor (DT) MR imaging provide quantitative indices with increased specificity to the most destructive aspects of MS. To increase our understanding of the pathophysiologic

Giuseppe Iannucci; Marco Rovaris; Laura Giacomotti; Giancarlo Comi; Massimo Filippi

2001-01-01

219

Optical-Input, Optical-Output Morphological Processor  

NASA Technical Reports Server (NTRS)

Some advantages of optical and electronic processing combined. Proposed optical-input/optical-output morphological processor is optoelectronic assembly performing some binary operations on picture elements of binary input image, yielding processed binary output image. Number of such processors cascaded to form more complicated image-processing system. Use of optics as connection medium makes rate of processing faster than in all-electronic system designed to perform same overall processing functions. At the same time, use of electronics as processing medium provides flexibility of reconfiguration not available in all-optical system.

Yu, Jeffrey W.; Chao, Tien Hsin; Cheng, Li Jen; Psaltis, Demetri

1992-01-01

220

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

221

Wind Profiles Derived from Volume Imaging Lidar Data: Enhancements to the Algorithm and Comparisons with Insitu Observations.  

National Technical Information Service (NTIS)

This paper presents wind measurements made with the University of Wisconsin Volume Imaging Lidar (VIL) during Aug. 1989 as part of the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE). Enhancements to the alg...

A. K. Piironen, E. W. Eloranta

1992-01-01

222

Sea Surface Current Estimates off Central California as Derived from Enhanced AVHRR (Advanced Very High Resolution Radiometer) Infrared Images.  

National Technical Information Service (NTIS)

A technique is presented which uses an interactive computer program to estimate sea surface current velocities from the displacement of sea surface temperature (SST) patterns apparent in enhanced sequential infrared images obtained from the NOAA-6 Advance...

C. M. Fang

1987-01-01

223

Long-term time-lapse multimodal intravital imaging of regeneration and bone-marrow-derived cell dynamics in skin  

PubMed Central

A major challenge for translating cell-based therapies is understanding the dynamics of cells and cell populations in complex in vivo environments. Intravital microscopy has shown great promise for directly visualizing cell behavior in vivo. However, current methods are limited to relatively short imaging times (hours), by ways to track cell and cell population dynamics over extended time-lapse periods (days to weeks to months), and by relatively few imaging contrast mechanisms that persist over extended investigations. We present technology to visualize and quantify complex, multifaceted dynamic changes in natural deformable skin over long time periods using novel multimodal imaging and a non-rigid image registration method. These are demonstrated in green fluorescent protein (GFP) bone marrow (BM) transplanted mice to study dynamic skin regeneration. This technology provides a novel perspective for studying dynamic biological processes and will enable future studies of stem, immune, and tumor cell biology in vivo. PMID:25089085

Graf, Benedikt W.; Chaney, Eric J.; Marjanovic, Marina; Adie, Steven G.; De Lisio, Michael; Valero, M. Carmen; Boppart, Marni D.; Boppart, Stephen A.

2014-01-01

224

COMPARISON OF UNMIXING RESULTS DERIVED FROM AVIRIS, HIGH AND LOW RESOLUTION, AND HYDICE IMAGES AT CUPRITE, NV  

Microsoft Academic Search

IntroductionThe availability of low-altitude, high-spatial-resolution AVIRIS (Green et al, 1998) images and high-resolutionHYDICE (Basedow et al, 1995) images over Cuprite, Nevada has provided an unprecedented opportunity tocompare the radiometric quality, the ability to detect end-members and the application of matched filters to threedifferent data sets in an area that is well-understood mineralogically. An earlier paper (Goetz and Kindel, 1996)compared high-altitude

Alexander F. H. Goetz; Bruce Kindel

225

Synthesis, biological evaluation and radiochemical labeling of a dansylhydrazone derivative as a potential imaging agent for apoptosis  

Microsoft Academic Search

To develop a small molecule-based tracer for in vivo apoptosis imaging, dansylhydrazone (DFNSH) was synthesized in 93% yield in less than 30min. The biological evaluation showed that DFNSH selectively binds to paclitaxel-induced apoptotic cancer cells. The high magnification fluorescent images demonstrate that DFNSH is localized within the cytoplasm of cells that bound Alexa® 488 labeled annexin V on the plasma

Wenbin Zeng; Min-liang Yao; David Townsend; George Kabalka; Jonathan Wall; Michael Le Puil; John Biggerstaff; Weimin Miao

2008-01-01

226

Code Completion From Abbreviated Input  

E-print Network

Abbreviation Completion is a novel technique to improve the efficiency of code-writing by supporting code completion of multiple keywords based on non-predefined abbreviated input - a different approach from conventional ...

Miller, Robert C.

227

World Input-Output Network  

E-print Network

Economic systems, traditionally analyzed as almost independent national systems, are increasingly connected on a global scale. Only recently becoming available, the World Input-Output Database (WIOD) is one of the first efforts to construct the multi-regional input-output (MRIO) tables at the global level. By viewing the world input-output system as an interdependent network where the nodes are the individual industries in different economies and the edges are the monetary goods flows between industries, we study the network properties of the so-called world input-output network (WION) and document its evolution over time. We are able to quantify not only some global network properties such as assortativity, clustering coefficient, and degree and strength distributions, but also its subgraph structure and dynamics by using community detection techniques. Over time, we detect a marked increase in cross-country connectivity of the production system, only temporarily interrupted by the 2008-2009 crisis. Moreover...

Cerina, Federica; Chessa, Alessandro; Riccaboni, Massimo

2014-01-01

228

System monitors discrete computer inputs  

NASA Technical Reports Server (NTRS)

Computer system monitors inputs from checkout devices. The comparing, addressing, and controlling functions are performed in the I/O unit. This leaves the computer main frame free to handle memory, access priority, and interrupt instructions.

Burns, J. J.

1966-01-01

229

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

230

Wind Profiles Derived from Volume Imaging Lidar Data: Enhancements to the Algorithm and Comparisons with Insitu Observations  

NASA Technical Reports Server (NTRS)

This paper presents wind measurements made with the University of Wisconsin Volume Imaging Lidar (VIL) during Aug. 1989 as part of the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE). Enhancements to the algorithm are described. Comparisons of these results to aircraft, balloon, and surface based wind measurements are presented. Observations of the spatial variance of aerosol backscatter are also compared to measurements of the convective boundary layer depth. Measurements are based on two-dimensional cross correlations between horizontal image planes showing the spatial distribution of aerosol scattering observed by the lidar at intervals of approximately 3 minutes. Each image plane covers an area of 500-1000 sq km and the winds calculated represent area averages.

Piironen, A. K.; Eloranta, E. W.

1992-01-01

231

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. PMID:19116186

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

232

Teaching Image Formation by Extended Light Sources: The Use of a Model Derived from the History of Science  

ERIC Educational Resources Information Center

This research, carried out in Greece on pupils aged 12-16, focuses on the transformation of their representations concerning light emission and image formation by extended light sources. The instructive process was carried out in two stages, each one having a different, distinct target set. During the first stage, the appropriate conflict…

Dedes, Christos; Ravanis, Konstantinos

2009-01-01

233

Characterization of conductive nanobiomaterials derived from viral assemblies by low-voltage STEM imaging and Raman scattering  

NASA Astrophysics Data System (ADS)

New technologies require the development of novel nanomaterials that need to be fully characterized to achieve their potential. High-resolution low-voltage scanning transmission electron microscopy (STEM) has proven to be a very powerful technique in nanotechnology, but its use for the characterization of nanobiomaterials has been limited. Rotavirus VP6 self-assembles into nanotubular assemblies that possess an intrinsic affinity for Au ions. This property was exploited to produce hybrid nanobiomaterials by the in situ functionalization of recombinant VP6 nanotubes with gold nanoparticles. In this work, Raman spectroscopy and advanced analytical electron microscopy imaging with spherical aberration-corrected (Cs) STEM and nanodiffraction at low-voltage doses were employed to characterize nanobiomaterials. STEM imaging revealed the precise structure and arrangement of the protein templates, as well as the nanostructure and atomic arrangement of gold nanoparticles with high spatial sub-Angstrom resolution and avoided radiation damage. The imaging was coupled with backscattered electron imaging, ultra-high resolution scanning electron microscopy and x-ray spectroscopy. The hybrid nanobiomaterials that were obtained showed unique properties as bioelectronic conductive devices and showed enhanced Raman scattering by their precise arrangement into superlattices, displaying the utility of viral assemblies as functional integrative self-assembled nanomaterials for novel applications.

Plascencia-Villa, Germán; Carreño-Fuentes, Liliana; Bahena, Daniel; José-Yacamán, Miguel; Palomares, Laura A.; Ramírez, Octavio T.

2014-09-01

234

EXE: Automatically Generating Inputs of Death Cristian Cadar, Vijay Ganesh, Peter M. Pawlowski, David L. Dill, Dawson R. Engler  

E-print Network

EXE: Automatically Generating Inputs of Death Cristian Cadar, Vijay Ganesh, Peter M. Pawlowski on manually or randomly constructed input, EXE runs it on symbolic input initially allowed to be ``any­ thing.'' As checked code runs, EXE tracks the constraints on each symbolic (i.e., input­derived) memory location

Engler, Dawson

235

EXE: Automatically Generating Inputs of Death Cristian Cadar, Vijay Ganesh, Peter M. Pawlowski, David L. Dill, Dawson R. Engler  

E-print Network

EXE: Automatically Generating Inputs of Death Cristian Cadar, Vijay Ganesh, Peter M. Pawlowski on manually or randomly constructed input, EXE runs it on symbolic input initially allowed to be "any- thing." As checked code runs, EXE tracks the constraints on each symbolic (i.e., input-derived) memory location

Engler, Dawson

236

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

237

Alignment of range image data based on MEMS IMU and coarse 3D models derived from evacuation plans  

NASA Astrophysics Data System (ADS)

Within the paper, we present an approach for the alignment of point clouds collected by the RGB-D sensor Microsoft Kinect, using a MEMS IMU and a coarse 3D model derived from a photographed evacuation plan. In this approach, the alignment of the point clouds is based on the sensor pose, which is computed from the analysis of the user's track, normal vectors of the ground points, and the information extracted from the coarse 3D model. The user's positions are derived from a foot mounted MEMS IMU, based on zero velocity updates, and also the information extracted from a coarse 3D model. We will then estimate the accuracy of point cloud alignment using this approach, and discuss about the applications of this method in indoor modeling of buildings.

Khosravani, Ali M.; Peter, Michael; Fritsch, Dieter

2013-04-01

238

MR Elastography Derived Shear Stiffness - A New Imaging Biomarker for the Assessment of Early Tumor Response to Chemotherapy  

PubMed Central

Purpose The overall goal is to develop MR Elastography (MRE) 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. MRE 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 MRE-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 MRE-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. 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.

2014-01-01

239

Images of Gravitational and Magnetic Phenomena Derived from Two-dimensional Back-projection Doppler Tomography of Interacting Binary Stars  

NASA Astrophysics Data System (ADS)

We have used two-dimensional back-projection Doppler tomography as a tool to examine the influence of gravitational and magnetic phenomena in interacting binaries that undergo mass transfer from a magnetically active star onto a non-magnetic main-sequence star. This multitiered study of over 1300 time-resolved spectra of 13 Algol binaries involved calculations of the predicted dynamical behavior of the gravitational flow and the dynamics at the impact site, analysis of the velocity images constructed from tomography, and the influence on the tomograms of orbital inclination, systemic velocity, orbital coverage, and shadowing. The H? tomograms revealed eight sources: chromospheric emission, a gas stream along the gravitational trajectory, a star-stream impact region, a bulge of absorption or emission around the mass-gaining star, a Keplerian accretion disk, an absorption zone associated with hotter gas, a disk-stream impact region, and a hot spot where the stream strikes the edge of a disk. We described several methods used to extract the physical properties of the emission sources directly from the velocity images, including S-wave analysis, the creation of simulated velocity tomograms from hydrodynamic simulations, and the use of synthetic spectra with tomography to sequentially extract the separate sources of emission from the velocity image. In summary, the tomography images have revealed results that cannot be explained solely by gravitational effects: chromospheric emission moving with the mass-losing star, a gas stream deflected from the gravitational trajectory, and alternating behavior between stream state and disk state. Our results demonstrate that magnetic effects cannot be ignored in these interacting binaries.

Richards, Mercedes T.; Cocking, Alexander S.; Fisher, John G.; Conover, Marshall J.

2014-11-01

240

Entropy-based measures of in vivo cilia-driven microfluidic mixing derived from quantitative optical imaging  

NASA Astrophysics Data System (ADS)

Motile cilia are cellular organelles that project from different epithelial surfaces including respiratory epithelium. They generate directional fluid flow that removes harmful pathogens and particulate matter from the respiratory system. While it has been known that primary ciliary dyskinesia increases the risk of recurrent pulmonary infections, there is now heightened interest in understanding the role that cilia play in a wide-variety of respiratory diseases. Different optical imaging technologies are being investigated to visualize cilia-driven fluid flow, and quantitative image analysis is used to generate measures of ciliary performance. Here, we demonstrate the quantification of in vivo cilia-driven microfluidic mixing using spatial and temporal measures of Shannon information entropy. Using videomicroscopy, we imaged in vivo cilia-driven fluid flow generated by the epidermis of the Xenopus tropicalis embryo. Flow was seeded with either dyes or microparticles. Both spatial and temporal measures of entropy show significant levels of mixing, with maximum entropy measures of ~6.5 (out of a possible range of 0 to 8). Spatial entropy measures showed localization of mixing "hot-spots" and "cold-spots" and temporal measures showed mixing throughout.In sum, entropy-based measures of microfluidic mixing can characterize in vivo cilia-driven fluid flow and hold the potential for better characterization of ciliary dysfunction.

Chandrasekera, Kenny; Jonas, Stephan; Bhattacharya, Dipankan; Khokha, Mustafa; Choma, Michael A.

2012-02-01

241

Micro-CT image-derived metrics quantify arterial wall distensibility reduction in a rat model of pulmonary hypertension  

NASA Astrophysics Data System (ADS)

We developed methods to quantify arterial structural and mechanical properties in excised rat lungs and applied them to investigate the distensibility decrease accompanying chronic hypoxia-induced pulmonary hypertension. Lungs of control and hypertensive (three weeks 11% O2) animals were excised and a contrast agent introduced before micro-CT imaging with a special purpose scanner. For each lung, four 3D image data sets were obtained, each at a different intra-arterial contrast agent pressure. Vessel segment diameters and lengths were measured at all levels in the arterial tree hierarchy, and these data used to generate features sensitive to distensibility changes. Results indicate that measurements obtained from 3D micro-CT images can be used to quantify vessel biomechanical properties in this rat model of pulmonary hypertension and that distensibility is reduced by exposure to chronic hypoxia. Mechanical properties can be assessed in a localized fashion and quantified in a spatially-resolved way or as a single parameter describing the tree as a whole. Micro-CT is a nondestructive way to rapidly assess structural and mechanical properties of arteries in small animal organs maintained in a physiological state. Quantitative features measured by this method may provide valuable insights into the mechanisms causing the elevated pressures in pulmonary hypertension of differing etiologies and should become increasingly valuable tools in the study of complex phenotypes in small-animal models of important diseases such as hypertension.

Johnson, Roger H.; Karau, Kelly L.; Molthen, Robert C.; Haworth, Steven T.; Dawson, Christopher A.

2000-04-01

242

Classifying input for active games  

Microsoft Academic Search

Active games are video games that involve physical activity. Active games capture input via a variety of devices such as accelerometers, cameras, pressure sensors and exercise equipment. Although active games have become highly popular, the interaction styles they support are poorly understood, and largely driven by the capabilities of individual hardware devices. In order to allow for a standard development

Tadeusz Stach; T. C. Nicholas Graham; Matthew Brehmer; Andreas Hollatz

2009-01-01

243

Signal Prediction With Input Identification  

NASA Technical Reports Server (NTRS)

A novel coding technique is presented for signal prediction with applications including speech coding, system identification, and estimation of input excitation. The approach is based on the blind equalization method for speech signal processing in conjunction with the geometric subspace projection theory to formulate the basic prediction equation. The speech-coding problem is often divided into two parts, a linear prediction model and excitation input. The parameter coefficients of the linear predictor and the input excitation are solved simultaneously and recursively by a conventional recursive least-squares algorithm. The excitation input is computed by coding all possible outcomes into a binary codebook. The coefficients of the linear predictor and excitation, and the index of the codebook can then be used to represent the signal. In addition, a variable-frame concept is proposed to block the same excitation signal in sequence in order to reduce the storage size and increase the transmission rate. The results of this work can be easily extended to the problem of disturbance identification. The basic principles are outlined in this report and differences from other existing methods are discussed. Simulations are included to demonstrate the proposed method.

Juang, Jer-Nan; Chen, Ya-Chin

1999-01-01

244

Resources Abstracts Input Transaction Form  

E-print Network

in the western half of North. America. There are two main varieties of rainbow trout, a sea-going form known#12;Resources Abstracts Input Transaction Form 4. Title 5. Report Date 6.Urban Aquaculture of the Rainbow Trout (Salmo gairdneri) 8. Performing Organization Report No.7. Author(s) Albert Jose Jones 10

District of Columbia, University of the

245

Late gestation fetal magnetic resonance imaging-derived total lung volume predicts postnatal survival and need for extracorporeal membrane oxygenation support in isolated congenital diaphragmatic hernia  

PubMed Central

Purpose Magnetic resonance imaging (MRI) has been used as an imaging modality to assess pulmonary hypoplasia in congenital diaphragmatic hernias (CDHs). The objective of this study was to determine if there is a correlation between late gestational fetal MRI–derived total lung volumes (TLVs) and CDH outcomes. Methods From 2006 to 2009, 44 patients met criteria of an isolated CDH with a late gestational MRI evaluation. The prenatal TLV (in milliliters) was obtained between 32 and 34 weeks gestation. The measured study outcomes included survival, need for extracorporeal membrane oxygenation (ECMO), and length of stay. Results There were 39 left and 5 right CDH patients. The average TLV was significantly lower for nonsurvivors (P = .01), and there was a significant association between lower TLV and the need for ECMO (P = .0001). When stratified by TLV, patients with a TLV of greater than 40 mL had a 90% survival vs 35% survival for a TLV of less than 20 mL. Furthermore, patients with a TLV greater than 40 mL had a lower rate of ECMO use (10%) than patients with a TLV of less than 20 mL (86%). Shorter length of stay was found to correlate with increasing TLV (P = .022). Conclusion Late gestation fetal MRI–derived TLV significantly correlates with postnatal survival and need for ECMO. Fetal MRI may be useful for the evaluation of patients who present late in gestation with a CDH. PMID:21683216

Lee, Timothy C.; Lim, Foong Y.; Keswani, Sundeep G.; Frischer, Jason S.; Haberman, Beth; Kingma, Paul S.; Habli, Mounira; Jaekle, Ronald K.; Sharp, Gina; Kline-Fath, Beth; Rubio, Eva I.; Calvo, Maria; Guimaraes, Carolina; Crombleholme, Timothy M.

2013-01-01

246

Correlations between Functional Imaging Markers Derived from PET/CT and Diffusion-Weighted MRI in Diffuse Large B-Cell Lymphoma and Follicular Lymphoma  

PubMed Central

Objectives To investigate the correlations between functional imaging markers derived from positron emission tomography/computed tomography (PET/CT) and diffusion-weighted magnetic resonance imaging (DWI) in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). Further to compare the usefulness of these tumor markers in differentiating diagnosis of the two common types of Non-Hodgkin's lymphoma (NHL). Materials and Methods Thirty-four consecutive pre-therapy adult patients with proven NHL (23 DLBCL and 11 FL) underwent PET/CT and MRI examinations and laboratory tests. The maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and metabolic tumor burden (MTB) were determined from the PET/CT images. DWI was performed in addition to conventional MRI sequences using two b values (0 and 800 s/mm2). The minimum and mean apparent diffusion coefficient (ADCmin and ADCmean) were measured on the parametric ADC maps. Results The SUVmax correlated inversely with the ADCmin (r?=??0.35, p<0.05). The ADCmin, ADCmean, serum thymidine kinase (TK), Beta 2-microglobulin (B2m), lactate dehydrogenase (LD), and C-reactive protein (CRP) correlated with both whole-body MTV and whole-body MTB (p<0.05 or 0.01). The SUVmax, TK, LD, and CRP were significantly higher in the DLBCL group than in the FL group. Receiver operating characteristic curve analysis showed that they were reasonable predictors in differentiating DLBCL from FL. Conclusions The functional imaging markers determined from PET/CT and DWI are associated, and the SUVmax is superior to the ADCmin in differentiating DLBCL from FL. All the measured serum markers are associated with functional imaging markers. Serum LD, TK, and CRP are useful in differentiating DLBCL from FL. PMID:24454777

Wu, Xingchen; Pertovaara, Hannu; Korkola, Pasi; Dastidar, Prasun; Jarvenpaa, Ritva; Eskola, Hannu; Kellokumpu-Lehtinen, Pirkko-Liisa

2014-01-01

247

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

248

High-resolution intravital imaging reveals that blood-derived macrophages but not resident microglia facilitate secondary axonal dieback in traumatic spinal cord injury.  

PubMed

After traumatic spinal cord injury, functional deficits increase as axons die back from the center of the lesion and the glial scar forms. Axonal dieback occurs in two phases: an initial axon intrinsic stage that occurs over the first several hours and a secondary phase which takes place over the first few weeks after injury. Here, we examine the secondary phase, which is marked by infiltration of macrophages. Using powerful time-lapse multi-photon imaging, we captured images of interactions between Cx3cr1(+/GFP) macrophages and microglia and Thy-1(YFP) axons in a mouse dorsal column crush spinal cord injury model. Over the first few weeks after injury, axonal retraction bulbs within the lesion are static except when axonal fragments are lost by a blebbing mechanism in response to physical contact followed by phagocytosis by mobile Cx3Cr1(+/GFP) cells. Utilizing a radiation chimera model to distinguish marrow-derived cells from radio-resistant CNS-resident microglia, we determined that the vast majority of accumulated cells in the lesion are derived from the blood and only these are associated with axonal damage. Interestingly, CNS-resident Cx3Cr1(+/GFP) microglia did not increasingly accumulate nor participate in neuronal destruction in the lesion during this time period. Additionally, we found that the blood-derived cells consisted mainly of singly labeled Ccr2(+/RFP) macrophages, singly labeled Cx3Cr1(+/GFP) macrophages and a small population of double-labeled cells. Since all axon destructive events were seen in contact with a Cx3Cr1(+/GFP) cell, we infer that the CCR2 single positive subset is likely not robustly involved in axonal dieback. Finally, in our model, deletion of CCR2, a chemokine receptor, did not alter the position of axons after dieback. Understanding the in vivo cellular interactions involved in secondary axonal injury may lead to clinical treatment candidates involving modulation of destructive infiltrating blood monocytes. PMID:24468477

Evans, Teresa A; Barkauskas, Deborah S; Myers, Jay T; Hare, Elisabeth G; You, Jing Qiang; Ransohoff, Richard M; Huang, Alex Y; Silver, Jerry

2014-04-01

249

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. PMID:24991202

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

2014-01-01

250

Imaging.  

PubMed

Imaging of the musculoskeletal system includes many modalities and is an area that is changing rapidly. Selection of the most accurate techniques and avoidance of duplication are vital to both good patient care and cost containment. PMID:3466135

Wilkinson, R

1986-12-01

251

Imaging Abeta plaques in living transgenic mice with multiphoton microscopy and methoxy-X04, a systemically administered Congo red derivative.  

PubMed

The identification of amyloid deposits in living Alzheimer disease (AD) patients is important for both early diagnosis and for monitoring the efficacy of newly developed anti-amyloid therapies. Methoxy-X04 is a derivative of Congo red and Chrysamine-G that contains no acid groups and is therefore smaller and much more lipophilic than Congo red or Chrysamine-G. Methoxy-X04 retains in vitro binding affinity for amyloid beta (Abeta) fibrils (Ki = 26.8 nM) very similar to that of Chrysamine-G (Ki = 25.3 nM). Methoxy-X04 is fluorescent and stains plaques, tangles, and cerebrovascular amyloid in postmortem sections of AD brain with good specificity. Using multiphoton microscopy to obtain high-resolution (1 microm) fluorescent images from the brains of living PSI/APP mice, individual plaques could be distinguished within 30 to 60 min after a single i.v. injection of 5 to 10 mg/kg methoxy-X04. A single i.p. injection of 10 mg/kg methoxy-X04 also produced high contrast images of plaques and cerebrovascular amyloid in PSI/APP mouse brain. Complementary quantitative studies using tracer doses of carbon- 11-labeled methoxy-X04 show that it enters rat brain in amounts that suggest it is a viable candidate as a positron emission tomography (PET) amyloid-imaging agent for in vivo human studies. PMID:12230326

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

2002-09-01

252

In Vivo Classification of Breast Masses Using Features Derived From Axial-Strain and Axial-Shear Images  

PubMed Central

Breast cancer is currently the second leading cause of cancer deaths in women. Early detection and accurate classification of suspicious masses as benign or malignant is important for arriving at an appropriate treatment plan. In this article, we present classification results for features extracted from ultrasound-based, axial-strain and axial-shear images of breast masses. The breast-mass stiffness contrast, size ratio, and a normalized axial-shear strain area feature are evaluated for the classification of in vivo breast masses using a leave-one-out classifier. Radiofrequency echo data from 123 patients were acquired using Siemens Antares or Elegra clinical ultrasound systems during freehand palpation. Data from four different institutions were analyzed. Axial displacements and strains were estimated using a multilevel, pyramid-based two-dimensional cross-correlation algorithm, with final processing block dimensions of 0.385 mm × 0.507 mm (three A-lines). Since mass boundaries on B-mode images for 21 patients could not be delineated (isoechoic), the combined feature analysis was only performed for 102 patients. Results from receiver operating characteristic (ROC) demonstrate that the area under the curve was 0.90, 0.84, and 0.52 for the normalized axial-shear strain, size ratio, and stiffness contrast, respectively. When these three features were combined using a leave-one-out classifier and support vector machine approach, the overall area under the curve improved to 0.93. PMID:23160475

Xu, Haiyan; Varghese, Tomy; Jiang, Jingfeng; Zagzebski, James A.

2013-01-01

253

Bis(Methylpyridine)-EDTA Derivative as a Potential Ligand for PET Imaging: Synthesis, Complexation, and Biological Evaluation.  

PubMed

A novel transitional metal ligand derivatized from EDTA-conjugated 2-amino-4-methyl pyridine, an acyclic vehicle (EDTA-Mepy2 ) was designed, synthesized, and characterized for PET imaging with (68) Ga. The drug likeliness and appropriate lipophilicity were first analyzed by molecular docking studies which shows interactive property of ligand with serum albumin protein (HSA: PDB 1E78), at Lys199, Arg257, and His242 residues, which make it more appropriate in transportation as a specific ligand for PET imaging. As a confirmation, binding constant of the ligand with human serum albumin was calculated at ?ex  = 350 nm which was found to be 4.9 × 10(3)  m(-1) . The pharmacokinetics of (68) Ga-EDTA-Mepy2 was analyzed by blood kinetics (t1/2 slow: 3 h 56 min and t1/2 fast: 32 min) and biodistribution (maximum%ID/g was found in kidney at 1 h). Further the capability of this ligand was analyzed as optical marker also, by recording ?ex  = 380 nm, RFU = 8000; 710 nm, RFU = 1000 units at fixed ?em  = 280 nm. Additionally, in physiological conditions where its stability was calculated, suggests 15-20 times selectivity over the endogenously present metal ions (KG aL /KZ nL  = 14.3, KG aL /KC uL  = 18.1). PMID:24894071

Singh, Pooja; Aggarwal, Swati; Tiwari, Anjani K; Kumar, Vikas; Pratap, Ramendra; Chuttani, Krishna; Mishra, Anil K

2014-12-01

254

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

255

Inputs for subject-specific computational fluid dynamics simulation of blood flow in the mouse aorta.  

PubMed

Mouse models are an important way for exploring relationships between blood hemodynamics and eventual plaque formation. We have developed a mouse model of aortic regurgitation (AR) that produces large changes in plaque burden with charges in hemodynamics [Zhou et al., 2010, "Aortic Regurgitation Dramatically Alters the Distribution of Atherosclerotic Lesions and Enhances Atherogenesis in Mice," Arterioscler. Thromb. Vasc. Biol., 30(6), pp. 1181-1188]. In this paper, we explore the amount of detail needed for realistic computational fluid dynamics (CFD) calculations in this experimental model. The CFD calculations use inputs based on experimental measurements from ultrasound (US), micro computed tomography (CT), and both anatomical magnetic resonance imaging (MRI) and phase contrast MRI (PC-MRI). The adequacy of five different levels of model complexity (a) subject-specific CT data from a single mouse; (b) subject-specific CT centerlines with radii from US; (c) same as (b) but with MRI derived centerlines; (d) average CT centerlines and averaged vessel radius and branching vessels; and (e) same as (d) but with averaged MRI centerlines) is evaluated by demonstrating their impact on relative residence time (RRT) outputs. The paper concludes by demonstrating the necessity of subject-specific geometry and recommends for inputs the use of CT or anatomical MRI for establishing the aortic centerlines, M-mode US for scaling the aortic diameters, and a combination of PC-MRI and Doppler US for estimating the spatial and temporal characteristics of the input wave forms. PMID:25070260

Van Doormaal, Mark; Zhou, Yu-Qing; Zhang, Xiaoli; Steinman, David A; Mark Henkelman, R

2014-10-01

256

Learning control of process systems with hard input constraints  

Microsoft Academic Search

In this paper, a novel and simple learning control strategy based on using a bounded nonlinear controller for process systems with hard input constraints is proposed. To enable the bounded nonlinear controller to learn to control a changing plant by merely observing the process output errors, a simple learning algorithm for parameter updating is derived based on the Lyapunov stability

Chyi-Tsong Chen; Shih-Tien Peng

1999-01-01

257

Optical properties of the Martian aerosols as derived from Imager for Mars Pathfinder midday sky brightness data  

NASA Astrophysics Data System (ADS)

It is well known that the aerosol play a major role in the energy budget of the Martian atmosphere. The importance of the aerosols for the radiative loading of the atmosphere has hence, direct impact on the Martian present weather and its seasonal cycle as well as consequences for its long term climate. Very accurate models of the sky brightness are required to separate the atmospheric illumination from the spectrum of the Martian surface, and hence to understand the mineralogy of the surface rocks and soil. Such accurate models are only possible if the optical properties of the Martian aerosols are known. In this work we analyze the images of the brightness of the Martian sky at midday acquired from the surface of the Mars during the Mars Pathfinder mission. The Imager for Mars Pathfinder (IMP) obtained data in filters centered at 443.6, 481.0, 670.8, 896.1 and 965.3 nm. Useful data sets were returned on sols 27, 40, 56, 65, 68, 74 and 82. Although the coverage in scattering angles of this sequence is limited to about 100°, having the Sun near zenith minimizes multiple scattering. This property should help in accuracy of constraining the size distribution and material properties. The shape of the particles can be expected to be less well constrained, as scattering events at angles around 150° are only present through multiple scattering. Data from sol 56 (Figure 1) were fitted with multiple scattering radiative transfer calculations to extract the size distribution, optical properties, and shape of the aerosols suspended in the atmosphere [1].

Shalygina, O. S.; Markiewicz, W. J.; Hviid, S. F.

2012-09-01

258

Input space versus feature space in kernel-based methods  

Microsoft Academic Search

This paper collects some ideas targeted at advancing our understanding of the feature spaces associated with support vector (SV) kernel functions. We first discuss the geometry of feature space. In particular, we review what is known about the shape of the image of input space under the feature space map, and how this influences the capacity of SV methods. Following

Bernhard Schölkopf; Sebastian Mika; Christopher J. C. Burges; Phil Knirsch; Klaus-robert Müller; Gunnar Rätsch; Alexander J. Smola

1999-01-01

259

Prediction of crude fat content of longissimus muscle of beef using the ratio of fat area calculated from computer image analysis: Comparison of regression equations for prediction using different input devices at different stations  

Microsoft Academic Search

Crude fat content of longissimus (ri- beye) muscle of beef cattle was predicted from a ratio of fat area (RFA) to area of ribeye muscle calculated from computer image analysis (CIA). Cross sections of 64 ribeyes taken from the 6-7th rib from cattle at experi- ment station A and cross sections of 94 ribeyes taken from the 6-7th rib from

K. Kuchida; S. Kono; K. Konishi; L. D. Van Vleck; M. Suzuki; S. Miyoshi; Roman L. Hruska

2010-01-01

260

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

261

Constraints for Input\\/Output Logics  

Microsoft Academic Search

In a previous paper we developed a general theory of input\\/output logics. These are operations resembling inference, but where inputs need not be included among outputs, and outputs need not be reusable as inputs. In the present paper we study what happens when they are constrained to render output consistent with input. This is of interest for deontic logic, where

David Makinson; Leendert van der Torre

2001-01-01

262

Images of Gravitational and Magnetic Phenomena Derived from 2D Back-Projection Doppler Tomography of Interacting Binary Stars  

E-print Network

We have used 2D back-projection Doppler tomography as a tool to examine the influence of gravitational and magnetic phenomena in interacting binaries which undergo mass transfer from a magnetically-active star onto a non-magnetic main sequence star. This multi-tiered study of over 1300 time-resolved spectra of 13 Algol binaries involved calculations of the predicted dynamical behavior of the gravitational flow and the dynamics at the impact site, analysis of the velocity images constructed from tomography, and the influence on the tomograms of orbital inclination, systemic velocity, orbital coverage, and shadowing. The H$\\alpha$ tomograms revealed eight sources: chromospheric emission, a gas stream along the gravitational trajectory, a star-stream impact region, a bulge of absorption or emission around the mass-gaining star, a Keplerian accretion disk, an absorption zone associated with hotter gas, a disk-stream impact region, and a hot spot where the stream strikes the edge of a disk. We described several me...

Richards, Mercedes T; Fisher, John G; Conover, Marshall J

2014-01-01

263

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

PubMed

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. PMID:23752742

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

2013-10-01

264

Photosensitive nanocapsules for use in imaging from poly(styrene-co-divinylbenzene) cross-linked with coumarin derivatives.  

PubMed

The study objective was to generate biocompatible probes and develop a stable macromolecule imaging system that are based on nanolipopolymersomes and can be used in living cells. We synthesized nanolipopolymersomes with a fluorescent polymer wall surrounded by an outer phospholipid shell that exhibits potential for the controlled delivery of diagnostic agents to cells. We describe a new type of probe suitable for dual detection methods (spectrophotometric and fluorescence). This aspect makes it unique among currently available probes because allows it to be detected with greater accuracy. We developed a highly fluorescent coumarinated polymer to overcome the limited brightness of conventional dyes with insufficient for long-term photostablility. Hydrophilic dyes (Lucifer yellow, Procion red, Procion blue) are entrapped in the aqueous core of stable polymeric nanocapsules with coumarin 6 embedded in a nanometre-thick poly(styrene-co-divinylbenzene) wall. Target compounds can be incorporated into nanocapsules in a single step. The hydrophilic phospholipids outer shell ensures biocompatibility and facilitates cell penetration. In this way, the novel fluorescent hybrid materials can help of nanotechnology. PMID:23893031

Sierant, Malgorzata; Paluch, Piotr; Florczak, Marcin; Rozanski, Artur; Miksa, Beata

2013-11-01

265

Application of imaging-derived parameters to dosimetry of intravascular brachytherapy sources: perturbation effects of residual plaque burden.  

PubMed

The dosimetric effect of geometric and material heterogeneities on intravascular brachytherapy dose delivery has been studied recently. Residual plaque within the coronary vessel appears to have an impact on the uniform delivery of radiation dose to the arterial tissue. In this study, we have examined the effect of residual plaque burden and post-PCI (percutaneous coronary intervention) plaque configuration on the dose to the arterial wall from clinical intravascular brachytherapy beta-emitting sources containing 32P and 90Sr/90Y. Monte Carlo simulations using the MCNP4B code were performed for these catheter-based sources with residual plaque burden ranging between 25% and 50%. The residual plaque burden values were derived from post-PCI data provided in several recent clinical studies. Dose calculations were performed for three different values of plaque density (1.45 g cm(-3), 2.20 g cm(-3), and 3.1 g cm(-3)) and three different plaque morphologies for the same residual plaque burden. The dose perturbation factor (DPF), defined as the ratio of dose at 2 mm radial distance for a given case to the dose at the same radial distance in homogeneous water medium, was determined for each of the three different plaque densities. The range of DPF values was 0.81-1.01, 0.62-0.99, and 0.41-0.97 for different plaque densities for the 32P source. Corresponding DPF values for the 90Sr/90Y source were 0.90-1.01, 0.84-1.01, and 0.62-1.01. The results indicate the need for accurate assessment of post-PCI clinical measurements such as minimal lumen diameter and residual plaque burden and incorporation of these values into dose calculations. PMID:12148741

Sehgal, Varun; Li, Zuofeng; Palta, Jatinder R; Smith, Karen M; Bolch, W E

2002-07-01

266

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

267

Functional transformations of odor inputs in the mouse olfactory bulb  

PubMed Central

Sensory inputs from the nasal epithelium to the olfactory bulb (OB) are organized as a discrete map in the glomerular layer (GL). This map is then modulated by distinct types of local neurons and transmitted to higher brain areas via mitral and tufted cells. Little is known about the functional organization of the circuits downstream of glomeruli. We used in vivo two-photon calcium imaging for large scale functional mapping of distinct neuronal populations in the mouse OB, at single cell resolution. Specifically, we imaged odor responses of mitral cells (MCs), tufted cells (TCs) and glomerular interneurons (GL-INs). Mitral cells population activity was heterogeneous and only mildly correlated with the olfactory receptor neuron (ORN) inputs, supporting the view that discrete input maps undergo significant transformations at the output level of the OB. In contrast, population activity profiles of TCs were dense, and highly correlated with the odor inputs in both space and time. Glomerular interneurons were also highly correlated with the ORN inputs, but showed higher activation thresholds suggesting that these neurons are driven by strongly activated glomeruli. Temporally, upon persistent odor exposure, TCs quickly adapted. In contrast, both MCs and GL-INs showed diverse temporal response patterns, suggesting that GL-INs could contribute to the transformations MCs undergo at slow time scales. Our data suggest that sensory odor maps are transformed by TCs and MCs in different ways forming two distinct and parallel information streams. PMID:25408637

Adam, Yoav; Livneh, Yoav; Miyamichi, Kazunari; Groysman, Maya; Luo, Liqun; Mizrahi, Adi

2014-01-01

268

A mathematical model for MIMO imaging  

NASA Astrophysics Data System (ADS)

Multiple Input Multiple Output- MIMO Radar is a fast growing research area. This paper will give a brief introduction to the subject as well as derive an image formation scheme. The general problem of radar imaging is to use some physical model for a transmitted signal, and measurements of the signal that is scattered back to a receiver by a scene to attempt to derive information about the scene. The concept of communication involves a message sender, a message receiver, and a channel. The sender sends a message through the channel to the receiver. The receiver attempts to recover the original message. MIMO communication is just communication that involves sending several messages to several recipients. The problem of Multiple Input Multiple Output Radar Imaging is to use the corruption of transmitted messages to try and derive useful information about the environment that the messages traveled through. The extra information gained with MIMO Radar can be used to get rid of false targets, detect moving targets, and create a better resolution image. The plan for this research is to culminate to an in-scene 3-d Image reconstruction algorithm. The model presented provides a context in which to examine this problem.

Cao, Yufeng; Lopez, Juan F., Jr.; Martinez, Alex; Qiao, Zhijun

2012-05-01

269

Status of input design for aircraft parameter identification  

NASA Technical Reports Server (NTRS)

Results are presented on the design of aircraft inputs (i.e. elevator, rudder and aeleron deflection time histories) to identify aircraft stability and control derivatives from flight test data. The problem is first reduced to an optimization problem with differential and integral constraints. The criteria used are either expressed in terms of the Cramer-Rao lower bound on the covariance matrix of the parameter estimates or in terms of the maximum prediction error variance. Both time-domain longitudinal and lateral dynamics of C-8 and Jet Star aircrafts and comparison with doublet type inputs are made.

Mehra, R. K.; Eupta, N. K.

1975-01-01

270

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

271

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

272

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

273

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.

2012-03-01

274

Input/output properties of the lateral vestibular nucleus  

NASA Technical Reports Server (NTRS)

This article is a review of work in three species, squirrel monkey, cat, and rat studying the inputs and outputs from the lateral vestibular nucleus (LVN). Different electrophysiological shock paradigms were used to determine the synaptic inputs derived from thick to thin diameter vestibular nerve afferents. Angular and linear mechanical stimulations were used to activate and study the combined and individual contribution of inner ear organs and neck afferents. The spatio-temporal properties of LVN neurons in the decerebrated rat were studied in response to dynamic acceleration inputs using sinusoidal linear translation in the horizontal head plane. Outputs were evaluated using antidromic identification techniques and identified LVN neurons were intracellularly injected with biocytin and their morphology studied.

Boyle, R.; Bush, G.; Ehsanian, R.

2004-01-01

275

Partial volume correction of the microPET blood input function using ensemble learning independent component analysis  

NASA Astrophysics Data System (ADS)

Medical images usually suffer from a partial volume effect (PVE), which may degrade the accuracy of any quantitative information extracted from the images. Our aim was to recreate accurate radioactivity concentration and time-activity curves (TACs) by microPET R4 quantification using ensemble learning independent component analysis (EL-ICA). We designed a digital cardiac phantom for this simulation and in order to evaluate the ability of EL-ICA to correct the PVE, the simulated images were convoluted using a Gaussian function (FWHM = 1-4 mm). The robustness of the proposed method towards noise was investigated by adding statistical noise (SNR = 2-16). During further evaluation, another set of cardiac phantoms were generated from the reconstructed images, and Poisson noise at different levels was added to the sinogram. In real experiments, four rat microPET images and a number of arterial blood samples were obtained; these were used to estimate the metabolic rate of FDG (MRFDG). Input functions estimated using the FastICA method were used for comparison. The results showed that EL-ICA could correct PVE in both the simulated and real cases. After correcting for the PVE, the errors for MRFDG, when estimated by the EL-ICA method, were smaller than those when TACs were directly derived from the PET images and when the FastICA approach was used.

Su, Kuan-Hao; Lee, Jih-Shian; Li, Jia-Hung; Yang, Yu-Wen; Liu, Ren-Shian; Chen, Jyh-Cheng

2009-03-01

276

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

277

Meta-analysis of peritumoural rCBV values derived from dynamic susceptibility contrast imaging in differentiating high-grade gliomas from intracranial metastases  

PubMed Central

Background and purpose: In the preoperative period, it is very important to accurately differentiate high-grade gliomas from intracranial metastases, as treatment strategies vary. Hence we performed a meta-analysis to evaluate the sensitivity and specificity of peritumoural relative cerebral blood volume (rCBV) values derived from dynamic susceptibility contrast imaging (DSCI) in differentiating high-grade gliomas from intracranial metastases. Materials and methods: Between 2004 and June 2014, relevant studies were searched from the databases of Medline and Embase for analysis. A total of 3 eligible studies were included in this analysis. Statistical analysis was performed with Meta-Disc 1.4. Results: A total of 136 patients included in the rCBV analysis: 79 with high-grade glioma and 57 with metastasis. The pooled sensitivity, specificity, positive likelihood ratio (+LR), negative likelihood ratio (-LR) and diagnostic odds ratio (DOR) for differentiating high-grade glioma from metastasis were 82% (95% CI 0.72-0.90), 96% (95% CI 0.88-1.00), 18.04 (95% CI 5.41-60.15), 0.19 (95% CI 0.12-0.31), and 90.20 (95% CI 23.10-352.27), respectively. The value of Cochran’s Q of DOR was 0.78 (P = 0.6774), and I2 was 0.0%, revealing that no statistically significant between-study heterogeneity was found. Conclusions: The results of this present study clearly present that the peritumoural rCBV values derived from DSCI could be used in distinguishing high-grade gliomas from intracranial metastases in the preoperative.

Liang, Ruofei; Wang, Xiang; Li, Mao; Yang, Yuan; Luo, Jiewen; Mao, Qing; Liu, Yanhui

2014-01-01

278

Power sharing analysis of double-input converters based on H-bridge cells  

Microsoft Academic Search

This paper concludes the previous works on the synthesis of double input converters based on H-bridge cells. First it derives a new double input converter topology called the boost-boost converter based on cascaded H-bridge cells. Next it presents a thorough power sharing analysis of the H-bridge based double input converters. Finally, it provides simulation results to support the theoretical outcomes.

Reza Ahmadi; Nima Yousefpoor; Mehdi Ferdowsi

2011-01-01

279

UP States Protect Ongoing Cortical Activity from Thalamic Inputs  

PubMed Central

Cortical neurons in vitro and in vivo fluctuate spontaneously between two stable membrane potentials: a depolarized UP state and a hyperpolarized DOWN state. UP states temporally correspond with multineuronal firing sequences which may be important for information processing. To examine how thalamic inputs interact with ongoing cortical UP state activity, we used calcium imaging and targeted whole-cell recordings of activated neurons in thalamocortical slices of mouse somatosensory cortex. Whereas thalamic stimulation during DOWN states generated multineuronal, synchronized UP states, identical stimulation during UP states had no effect on the subthreshold membrane dynamics of the vast majority of cells or on ongoing multineuronal temporal patterns. Both thalamocortical and corticocortical PSPs were significantly reduced and neuronal input resistance was significantly decreased during cortical UP states – mechanistically consistent with UP state insensitivity. Our results demonstrate that cortical dynamics during UP states are insensitive to thalamic inputs. PMID:19092994

Watson, Brendon O.; MacLean, Jason N.; Yuste, Rafael

2008-01-01

280

Image-Based Quantification of Benzoporphyrin Derivative Uptake, Localization, and Photobleaching in 3D Tumor Models, for Optimization of PDT Parameters  

PubMed Central

Photodynamic therapy (PDT) is a light-based treatment modality in which wavelength specific activation of a photosensitizer (PS) generates cytotoxic response in the irradiated region. PDT response is critically dependent on several parameters including light dose, PS dose, uptake time, fluence rate, and the mode of light delivery. While the systematic optimization of these treatment parameters can be complex, it also provides multiple avenues for enhancement of PDT efficacy under diverse treatment conditions, provided that a rational framework is established to quantify the impact of parameter selection upon treatment response. Here we present a theranostic technique, combining the inherent ability of the PS to serve simultaneously as a therapeutic and imaging agent, with the use of image-based treatment assessment in three dimensional (3D) in vitro tumor models, to comprise a platform to evaluate the impact of PDT parameters on treatment outcomes. We use this approach to visualize and quantify the uptake, localization, and photobleaching of the PS benzoporphyrin derivative monoacid ring-A (BPD) in a range of treatment conditions with varying uptake times as well as continuous and fractionated light delivery regimens in 3D cultures of AsPC-1 and PANC-1 cells. Informed by photobleaching patterns and correlation with cytotoxic response, asymmetric fractionated light delivery at 4 hours BPD uptake was found to be the most effective regimen assessed. Quantification of the spatial profile of cell killing within multicellular nodules revealed that these conditions also achieve the highest depth of cytotoxicity along the radial axis of 3D nodules. The framework introduced here provides a means for systematic assessment of PDT treatment parameters in biologically relevant 3D tumor models with potential for broader application to other systems. PMID:23082096

Glidden, Michael D.; Celli, Jonathan P.; Massodi, Iqbal; Rizvi, Imran; Pogue, Brian W.; Hasan, Tayyaba

2012-01-01

281

Derivative computation by multiscale filters  

Microsoft Academic Search

It is a common problem to compute the derivative of a signal in image processing and computer vision. So far, in most of the computational methods, the nth order derivative of a noisy signal is obtained by filtering the signal by a nth Order Derivative Filter (NODF), which is the nth order derivative of a smooth filter. In order to

Song De Ma; Bingcheng Li

1998-01-01

282

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

283

Test Generation with Inputs, Outputs, and Quiescence  

Microsoft Academic Search

This paper studies testing based on labelled transition systems, using the assumption that implementations communicate with their environment via inputs and outputs. Such implementations are formalized by restricting the class of transition systems to those systems that can always accept input actions, as in input\\/output automata. Implementation relations, formalizing the notion of conformance of these implementations with respect to labelled

Jan Tretmans

1996-01-01

284

History and alternative game input methods  

Microsoft Academic Search

Abstr act–This paper r eviews the history of input methods used for video games, in par ticular pr evious attempts at intr oducing alter native input methods and how successful they have been. It also aims to answer the questions: ‘What ar e player s’ per ceptions of alter native input methods? and ‘Can playing a game with an alter

Andrew Thorpe; Minhua Ma; Andreas Oikonomou

2011-01-01

285

Measurements of diagnostic examination performance and correlation analysis using microvascular leakage, cerebral blood volume, and blood flow derived from 3T dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging in glial tumor grading  

Microsoft Academic Search

Introduction  To assess the diagnostic accuracy of microvascular leakage (MVL), cerebral blood volume (CBV) and blood flow (CBF) values\\u000a derived from dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging (DSC-MR imaging) for grading of cerebral\\u000a glial tumors, and to estimate the correlation between vascular permeability\\/perfusion parameters and tumor grades.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  A prospective study of 79 patients with cerebral glial tumors underwent DSC-MR imaging. Normalized

Andrés Server; Bjørn A. Graff; Tone E. Døli Orheim; Till Schellhorn; Roger Josefsen; Øystein B. Gadmar; Per H. Nakstad

2011-01-01

286

Evaluating an Alternative Model for the Input Function in FDG-PET Studies 1  

E-print Network

Evaluating an Alternative Model for the Input Function in FDG-PET Studies 1 Hongbin Guo 2 Rosemary-D-glucose flu- oro (FDG) positron emission tomography (PET) brain studies with bolus injection is presented-derived expressions. The new model provides an effective means to recover the input function in FDG-PET studies

Renaut, Rosemary

287

A zero-placement technique for designing shaped inputs to suppress multiple-mode vibration  

Microsoft Academic Search

The performance of many flexible systems can be improved by employing command shaping techniques to reduce machine vibration. The input shaping technique, in particular, has proven to be highly effective for a wide class of systems. Due to the mathematical complexity of higher-order problems, multiple-mode input shapers can be tricky to derive and difficult to understand. This paper proposes a

Timothy D. Tuttle; Warren P. Seering

1994-01-01

288

An Experimental Study on Software Structural Testing: Deterministic versus Random Input Generation  

Microsoft Academic Search

The fault revealing power of different test patterns derived from ten structural test criteria currently referred to in unit testing is investigated. Experiments performed on four programs that are pieces of a real-life software system from the nuclear field are reported. Three test input generation techniques are studied: (1) deterministic choice, (2) random selection based on an input probability distribution

Pascale Thévenod-fosse; Hélène Waeselynck; Yves Crouzet

1991-01-01

289

A Web Browsing System by Eye-gaze Input  

NASA Astrophysics Data System (ADS)

We have developed an eye-gaze input system for people with severe physical disabilities, such as amyotrophic lateral sclerosis (ALS) patients. This system utilizes a personal computer and a home video camera to detect eye-gaze under natural light. The system detects both vertical and horizontal eye-gaze by simple image analysis, and does not require special image processing units or sensors. We also developed the platform for eye-gaze input based on our system. In this paper, we propose a new web browsing system for physically disabled computer users as an application of the platform for eye-gaze input. The proposed web browsing system uses a method of direct indicator selection. The method categorizes indicators by their function. These indicators are hierarchized relations; users can select the felicitous function by switching indicators group. This system also analyzes the location of selectable object on web page, such as hyperlink, radio button, edit box, etc. This system stores the locations of these objects, in other words, the mouse cursor skips to the object of candidate input. Therefore it enables web browsing at a faster pace.

Abe, Kiyohiko; Owada, Kosuke; Ohi, Shoichi; Ohyama, Minoru

290

Noninvasive high-resolution detection of the arterial and venous input function through a PET Wrist  

E-print Network

Noninvasive high-resolution detection of the arterial and venous input function through a PET Wrist using planar coincidence images. I. INTRODUCTION Quantitative Positron Emission Tomography (PET) often determine the input function. These techniques include external monitors and PET scanners that measure

291

Intravenous Administration of Human Umbilical Cord Blood-Derived AC133+ Endothelial Progenitor Cells in Rat Stroke Model Reduces Infarct Volume: Magnetic Resonance Imaging and Histological Findings  

PubMed Central

Abstract Endothelial progenitor cells (EPCs) hold enormous therapeutic potential for ischemic vascular diseases. Previous studies have indicated that stem/progenitor cells derived from human umbilical cord blood (hUCB) improve functional recovery in stroke models. Here, we examined the effect of hUCB AC133+ EPCs on stroke development and resolution in a middle cerebral artery occlusion (MCAo) rat model. Since the success of cell therapies strongly depends on the ability to monitor in vivo the migration of transplanted cells, we also assessed the capacity of magnetic resonance imaging (MRI) to track in vivo the magnetically labeled cells that were administered. Animals were subjected to transient MCAo and 24 hours later injected intravenously with 107 hUCB AC133+ EPCs. MRI performed at days 1, 7, and 14 after the insult showed accumulation of transplanted cells in stroke-affected hemispheres and revealed that stroke volume decreased at a significantly higher rate in cell-treated animals. Immunohistochemistry analysis of brain tissues localized the administered cells in the stroke-affected hemispheres only and indicated that these cells may have significantly affected the magnitude of endogenous proliferation, angiogenesis, and neurogenesis. We conclude that transplanted cells selectively migrated to the ischemic brain parenchyma, where they exerted a therapeutic effect on the extent of tissue damage, regeneration, and time course of stroke resolution. PMID:23934909

Iskander, Asm; Knight, Robert A.; Zhang, Zheng Gang; Ewing, James R.; Shankar, Adarsh; Varma, Nadimpalli Ravi S.; Bagher-Ebadian, Hassan; Ali, Meser M.; Arbab, Ali S.

2013-01-01

292

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

293

A hyperspectral image analysis workbench for environmental science applications  

SciTech Connect

A significant challenge to the information sciences is to provide more powerful and accessible means to exploit the enormous wealth of data available from high-resolution imaging spectrometry, or ``hyperspectral`` imagery, for analysis, for mapping purposes, and for input to environmental modeling applications. As an initial response to this challenge, Argonne`s Advanced Computer Applications Center has developed a workstation-based prototype software workbench which employs Al techniques and other advanced approaches to deduce surface characteristics and extract features from the hyperspectral images. Among its current capabilities, the prototype system can classify pixels by abstract surface type. The classification process employs neural network analysis of inputs which include pixel spectra and a variety of processed image metrics, including image ``texture spectra`` derived from fractal signatures computed for subimage tiles at each wavelength.

Christiansen, J.H.; Zawada, D.G.; Simunich, K.L.; Slater, J.C.

1992-10-01

294

A hyperspectral image analysis workbench for environmental science applications  

SciTech Connect

A significant challenge to the information sciences is to provide more powerful and accessible means to exploit the enormous wealth of data available from high-resolution imaging spectrometry, or hyperspectral'' imagery, for analysis, for mapping purposes, and for input to environmental modeling applications. As an initial response to this challenge, Argonne's Advanced Computer Applications Center has developed a workstation-based prototype software workbench which employs Al techniques and other advanced approaches to deduce surface characteristics and extract features from the hyperspectral images. Among its current capabilities, the prototype system can classify pixels by abstract surface type. The classification process employs neural network analysis of inputs which include pixel spectra and a variety of processed image metrics, including image texture spectra'' derived from fractal signatures computed for subimage tiles at each wavelength.

Christiansen, J.H.; Zawada, D.G.; Simunich, K.L.; Slater, J.C.

1992-01-01

295

Turn customer input into innovation.  

PubMed

It's difficult to find a company these days that doesn't strive to be customer-driven. Too bad, then, that most companies go about the process of listening to customers all wrong--so wrong, in fact, that they undermine innovation and, ultimately, the bottom line. What usually happens is this: Companies ask their customers what they want. Customers offer solutions in the form of products or services. Companies then deliver these tangibles, and customers just don't buy. The reason is simple--customers aren't expert or informed enough to come up with solutions. That's what your R&D team is for. Rather, customers should be asked only for outcomes--what they want a new product or service to do for them. The form the solutions take should be up to you, and you alone. Using Cordis Corporation as an example, this article describes, in fine detail, a series of effective steps for capturing, analyzing, and utilizing customer input. First come indepth interviews, in which a moderator works with customers to deconstruct a process or activity in order to unearth "desired outcomes." Addressing participants' comments one at a time, the moderator rephrases them to be both unambiguous and measurable. Once the interviews are complete, researchers then compile a comprehensive list of outcomes that participants rank in order of importance and degree to which they are satisfied by existing products. Finally, using a simple mathematical formula called the "opportunity calculation," researchers can learn the relative attractiveness of key opportunity areas. These data can be used to uncover opportunities for product development, to properly segment markets, and to conduct competitive analysis. PMID:12964470

Ulwick, Anthony W

2002-01-01

296

[Sensory input and basal ganglia].  

PubMed

Non-motor symptoms including sensory signs have recently been stressed in basal ganglia (BG) disorders. Why do sensory symptoms appear in BG disorders? Four closed loops have been shown between cortex and BG, but no sensory cortical-BG loops. I review two points: fiber connections between the somatosensory cortex and BG to explain sensory symptoms, and pain and basal ganglia. Somatosensory system and BG Many animal studies have shown somatosensory cortex- striatum- globus pallidus- motor thalamus connections, but no connections to the sensory thalamus. This indicates that sensory system may modulate four closed loops between the cortices and BG (motor loop, oculomotor loop, prefrontal loop and limbic loop) as an open loop system. Based on the above findings, two possible mechanisms may explain somatosensory symptoms in BG disorders. Motor modulation abnormalities may be considered as sensory symptoms in patients with BG disorders. Some sensory cognition abnormalities due to abnormal modulation of the prefrontal- BG loop may be considered as sensory symptoms. Pain and dopamine Two systems contribute to pain signs in patients with BG disorders. Descending pain modulation system: several brainstem nuclei send descending pain modulation fibers to the spinal cord mediated by serotonin or noradrenalin. These nuclei are facilitated by D2 neurons from the striatum. Striatal dopamine must suppress the pain information input at the spinal cord. Ascending pain relief system D2 neurons from the ventral tegmental area to anterior cingulate cortex, accumbens and amygdala may reduce pain feeling at the association cortices. In summary, dopamine system will reduce pain at the spinal cord and association cortices. Dopamine depletion, therefore, will enhance the pain sensation. PMID:23196445

Ugawa, Yoshikazu

2012-01-01

297

Optimizing multiresolution pixel-level image fusion  

Microsoft Academic Search

A number of pixel level image fusion schemes have been proposed in the past which combine registered input sensor images into a single fused output image. The two general objectives that underpin the operations of these schemes are a) the transfer of all visually important information form input images into a fused image and b) the minimization of undesirable distortions

Vladimir S. Petrovic; Costas S. Xydeas

2001-01-01

298

CARMENES. III. CARMENCITA, the input catalogue  

NASA Astrophysics Data System (ADS)

CARMENES, the new near-infrared/optical high-resolution spectrograph for the 3.5 m Calar Alto Telescope, is expected to see its first light in early 2014. Before that, we must have chosen carefully the 300 M dwarfs to which CARMENES will look for terrestrial exoplanets with the radial-velocity method under guaranteed time. CARMENCITA, the CARMENES Cool dwarf Information and daTa Archive, our ``input catalogue'', will be the most comprehensive database of M dwarfs ever built. It already contains dozens of parameters measured by us or compiled from the literature for over 1300 bright M dwarfs in the solar neighbourhood: coordinates, spectral indices, photometry at different bandpasses, parallaxes and spectro-photometric distances, rotational and radial velocities, H? equivalent widths, X-ray count rates and hardness ratios, close and wide multiplicity data, proper motions, Galactocentric space velocities, full references, and much more parameters. The private on-line catalogue, including preparatory science (i.e., high-resolution imaging, low- and high-resolution spectroscopy), will be eventually public as a CARMENES legacy.

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

2013-05-01

299

Input-State Feedback Linearization of Single-Input Nonlinear Time-Delay Systems  

E-print Network

1 Input-State Feedback Linearization of Single-Input Nonlinear Time-Delay Systems Kamel BAIBECHE problem for a class of single-input nonlinear time-delay systems is studied for the first time. Keywords : Input-state feedback linearization, Nonlinear time-delay systems, Linearizing output. I

Boyer, Edmond

300

Input estimation from measured structural response  

SciTech Connect

This report will focus on the estimation of unmeasured dynamic inputs to a structure given a numerical model of the structure and measured response acquired at discrete locations. While the estimation of inputs has not received as much attention historically as state estimation, there are many applications where an improved understanding of the immeasurable input to a structure is vital (e.g. validating temporally varying and spatially-varying load models for large structures such as buildings and ships). In this paper, the introduction contains a brief summary of previous input estimation studies. Next, an adjoint-based optimization method is used to estimate dynamic inputs to two experimental structures. The technique is evaluated in simulation and with experimental data both on a cantilever beam and on a three-story frame structure. The performance and limitations of the adjoint-based input estimation technique are discussed.

Harvey, Dustin [Los Alamos National Laboratory; Cross, Elizabeth [Los Alamos National Laboratory; Silva, Ramon A [Los Alamos National Laboratory; Farrar, Charles R [Los Alamos National Laboratory; Bement, Matt [Los Alamos National Laboratory

2009-01-01

301

Using model order tests to determine sensory inputs in a motion study  

NASA Technical Reports Server (NTRS)

In the study of motion effects on tracking performance, a problem of interest is the determination of what sensory inputs a human uses in controlling his tracking task. In the approach presented here a simple canonical model (FID or a proportional, integral, derivative structure) is used to model the human's input-output time series. A study of significant changes in reduction of the output error loss functional is conducted as different permutations of parameters are considered. Since this canonical model includes parameters which are related to inputs to the human (such as the error signal, its derivatives and integration), the study of model order is equivalent to the study of which sensory inputs are being used by the tracker. The parameters are obtained which have the greatest effect on reducing the loss function significantly. In this manner the identification procedure converts the problem of testing for model order into the problem of determining sensory inputs.

Repperger, D. W.; Junker, A. M.

1977-01-01

302

Programmable remapper for image processing  

NASA Technical Reports Server (NTRS)

A video-rate coordinate remapper includes a memory for storing a plurality of transformations on look-up tables for remapping input images from one coordinate system to another. Such transformations are operator selectable. The remapper includes a collective processor by which certain input pixels of an input image are transformed to a portion of the output image in a many-to-one relationship. The remapper includes an interpolative processor by which the remaining input pixels of the input image are transformed to another portion of the output image in a one-to-many relationship. The invention includes certain specific transforms for creating output images useful for certain defects of visually impaired people. The invention also includes means for shifting input pixels and means for scrolling the output matrix.

Juday, Richard D. (inventor); Sampsell, Jeffrey B. (inventor)

1991-01-01

303

Dust deflation by dust devils on Mars derived from optical depth measurements using the shadow method in HiRISE images  

NASA Astrophysics Data System (ADS)

We measured the optical depth of three separate dust devils and their surroundings with the so called "shadow method" in HiRISE images. The calculated optical depths of the dust devils range from 0.29±0.18 to 1.20±0.38. Conservative calculations of the minimum and maximum dust loads are in the range of 4-122 mg m-3. Assuming reliable upper and lower boundary values of vertical speeds within the dust devils between 0.1 and 10 ms-1 based on terrestrial and Martian studies we derived dust fluxes in the range of 6.3-1221 mg m-2 s-1 (PSP_004285_1375), from 0.38-162 mg m-2 s-1 (ESP_013545_1110), and from 3.2-581 mg m-2 s-1 (ESP_016306_2410) for the three dust devils. Our dust load and dust flux calculations for the three dust devils are in good agreement to previous studies. Two of the analyzed dust devils left continuous dark tracks on the surface. For these dust devils we could calculate how much dust was removed by using the minimum and maximum dust fluxes in combination with measured horizontal speeds of these dust devils. Our results indicate that a dust removal of an equivalent layer of less than 2 ?m (or less than one monolayer) is sufficient for the formation of dust devil tracks on Mars. This value might be used in future studies to estimate the contribution of dust devils to the global dust entrainment into the atmosphere on Mars.

Reiss, D.; Hoekzema, N. M.; Stenzel, O. J.

2014-04-01

304

Japanese Sentence Input Method Using Acceleration Sensor  

Microsoft Academic Search

\\u000a Digital pens are used for character input method without training. Some lecture support systems were developed by using pen\\u000a input, because of collecting remarks of student in a real time. We proposed a lecture support system by using Wiimote for\\u000a character input method. Because Wiimote has 3D acceleration sensor, a student writes a character in the air, and our system

Masaki Sugimoto; Kazufumi Nakai; Nobuo Ezaki; Kimiyasu Kiyota

305

Input scene restoration in pattern recognition correlator based on digital photo camera  

NASA Astrophysics Data System (ADS)

Diffraction image correlator based on commercial digital SLR photo camera was reported earlier. The correlator was proposed for recognition of external scenes illuminated by quasimonochromatic spatially incoherent light. The correlator hardware consists of digital camera with plugged in optical correlation filter unit and control computer. The kinoform used as correlation filter is placed in a free space of the SLR camera body between the interchangeable camera lens and the swing mirror. On the other hand, this correlator can be considered as a hybrid optical-digital imaging system with wavefront coding. It allows not only to recognize objects in input scene but to restore, if needed, the whole image of input scene from correlation signals distribution registered by SLR camera sensor. Linear methods for image reconstruction in the correlator are discussed. The experimental setup of the correlator and experimental results on images recognition and input scenes restoration are presented.

Starikov, Sergey N.; Balan, Nikita N.; Konnik, Mikhail V.; Rodin, Vladislav G.; Solyakin, Ivan V.; Shapkarina, Ekaterina A.

2007-04-01

306

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

307

Reinforcement learning with raw image pixels as input state  

E-print Network

. In many real-life problems, such as robot navigation ones, the state is made of visual percept. Up to now). For a given initial condition x0 = x, Jµ is defined as follows: Jµ (x) = lim N N-1 t=0 t r(xt, µ(xt)) (2

Wehenkel, Louis

308

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

309

Response of traveling waves to transient inputs in neural fields  

NASA Astrophysics Data System (ADS)

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.

Kilpatrick, Zachary P.; Ermentrout, Bard

2012-02-01

310

Managing Input during Assistive Technology Product Design  

ERIC Educational Resources Information Center

Many different sources of input are available to assistive technology innovators during the course of designing products. However, there is little information on which ones may be most effective or how they may be efficiently utilized within the design process. The aim of this project was to compare how three types of input--from simulation tools,…

Choi, Young Mi

2011-01-01

311

Computing Functions by Approximating the Input  

ERIC Educational Resources Information Center

In computing real-valued functions, it is ordinarily assumed that the input to the function is known, and it is the output that we need to approximate. In this work, we take the opposite approach: we show how to compute the values of some transcendental functions by approximating the input to these functions, and obtaining exact answers for their…

Goldberg, Mayer

2012-01-01

312

EDP Applications to Musical Bibliography: Input Considerations  

ERIC Educational Resources Information Center

The application of Electronic Data Processing (EDP) has been a boon in the analysis and bibliographic control of music. However, an extra step of encoding must be undertaken for input of music. The best hope to facilitate musical input is the development of an Optical Character Recognition (OCR) music-reading machine. (29 references) (Author/NH)

Robbins, Donald C.

1972-01-01

313

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

314

Replenishment of magma chambers by light inputs  

Microsoft Academic Search

Magma chambers, particularly those of basaltic composition, are often replenished by an influx of magma whose density is less than that of the resident magma. This paper describes the fundamental fluid mechanics involved in the replenishment by light inputs. If rho denotes the uniform density of the resident magma and rho-Deltarho that the input, the situation is described by the

Herbert E. Huppert; R. Stephen; J. Sparks; John A. Whitehead; Mark A. Halloworth

1986-01-01

315

BRANCH INPUT RESISTANCE AND STEADY ATTENUATION FOR  

E-print Network

attenuation depend upon the following: the number of den- dritic trees, the orders of dendritic branching, the electrotonic length of the den- dritic trees, the location of the dendritic input site, and the input the synaptic site to other locations, both in the same dendritic tree, at the neuron soma, and in other den

Levine, Alex J.

316

Wind Energy Input to the Ekman Layer  

Microsoft Academic Search

Wind stress energy input through the surface ageostrophic currents is studied. The surface ageostrophic velocity is calculated using the classical formula of the Ekman spiral, with the Ekman depth determined from an empirical formula. The total amount of energy input over the global oceans for subinertial frequency is estimated as 2.4 TW averaged over a period from 1997 to 2002,

Wei Wang; Rui Xin Huang

2004-01-01

317

Input Effects within a Constructionist Framework  

ERIC Educational Resources Information Center

Constructionist approaches to language hypothesize that grammar can be learned from the input using domain-general mechanisms. This emphasis has engendered a great deal of research--exemplified in the present issue--that seeks to illuminate the ways in which input-related factors can both drive and constrain constructional acquisition. In this…

Boyd, Jeremy K.; Goldberg, Adele E.

2009-01-01

318

The design space of input devices  

Microsoft Academic Search

A bewildering variety of devices for communication from humans to computers now exists on the market. In order to make sense of this variety, and to aid in the design of new input devices, we propose a framework for describing and analyzing input devices. Following Mackinlay's semantic analysis of the design space for graphical presentations, our goal is to provide

Stuart K. Card; Jock D. Mackinlay; George G. Robertson

1990-01-01

319

PULSE INPUT SEQUENCES FOR RESIDUAL VIBRATION REDUCTION  

Microsoft Academic Search

Preshaping of the input is a well known technique to reduce the vibration in a flexible structure. In this paper, inputs in the form of pulse sequences that are able to reduce the residual vibration in overhead crane are presented. If the exact natural frequency and damping ratio of the system are known, then the residual vibration can be eliminated

C. L. Teo; C. J. Ong; M. Xu

1998-01-01

320

Decimated Input Ensembles for Improved Generalization  

Microsoft Academic Search

Using an ensemble of classifiers instead ofa single classifier has been demonstrated to improve generalizationperformance in many difficult problems. However,for this improvement to take place it is necessary tomake the classifiers in an ensemble more complementary.In this paper, we highlight the need to reduce the correlationamong the component classifiers and investigate one methodfor correlation reduction: input decimation. We elaborateon input

Kagan Tumer; Moffett Field; Ca Nikunj C. Oza

1999-01-01

321

Code input alternatives John C. Wright  

E-print Network

language (XML) can be used for flexible data representation, gui data input via a browser, input validation, native database storage with read/write search access. A W3C standard that along with HTML/WebDAV gives can be stored in a native XML database (eXist or XML BDB.) XForms is a W3C standard. ­ In the process

Wright, John C.

322

Quantitative assessment of multiple sclerosis lesion load using CAD and expert input  

NASA Astrophysics Data System (ADS)

Multiple sclerosis (MS) is a frequently encountered neurological disease with a progressive but variable course affecting the central nervous system. Outline-based lesion quantification in the assessment of lesion load (LL) performed on magnetic resonance (MR) images is clinically useful and provides information about the development and change reflecting overall disease burden. Methods of LL assessment that rely on human input are tedious, have higher intra- and inter-observer variability and are more time-consuming than computerized automatic (CAD) techniques. At present it seems that methods based on human lesion identification preceded by non-interactive outlining by CAD are the best LL quantification strategies. We have developed a CAD that automatically quantifies MS lesions, displays 3-D lesion map and appends radiological findings to original images according to current DICOM standard. CAD is also capable to display and track changes and make comparison between patient's separate MRI studies to determine disease progression. The findings are exported to a separate imaging tool for review and final approval by expert. Capturing and standardized archiving of manual contours is also implemented. Similarity coefficients calculated from quantities of LL in collected exams show a good correlation of CAD-derived results vs. those incorporated as expert's reading. Combining the CAD approach with an expert interaction may impact to the diagnostic work-up of MS patients because of improved reproducibility in LL assessment and reduced time for single MR or comparative exams reading. Inclusion of CAD-generated outlines as DICOM-compliant overlays into the image data can serve as a better reference in MS progression tracking.

Gertych, Arkadiusz; Wong, Alexis; Sangnil, Alan; Liu, Brent J.

2008-03-01

323

Pixel-level image fusion: the case of image sequences  

Microsoft Academic Search

In pixel-level image sequence fusion, a composite image sequence has to be built of several spatially registered input image sequences. One of the primary goals in image sequence fusion is the temporal stability and consistency of the fused image sequence. To fulfill the preceding desiderata, we propose a novel approach based on a shift invariant extension of the 2D discrete

Oliver Rockinger; Thomas Fechner

1998-01-01

324

Single-image superresolution based on local regression and nonlocal self-similarity  

NASA Astrophysics Data System (ADS)

The challenge of learning-based superresolution (SR) is to predict the relationships between low-resolution (LR) patches and their corresponding high-resolution (HR) patches. By learning such relationships from external training images, the existing learning-based SR approaches are often affected by the relevance between the training data and the LR input image. Therefore, we propose a single-image SR method that learns the LR-HR relations from the given LR image itself instead of any external images. Both the local regression model and nonlocal patch redundancy are exploited in the proposed method. The local regression model is employed to derive the mapping functions between self-LR-HR example patches, and the nonlocal self-similarity gives rise to a high-order derivative estimation of the derived mapping function. Moreover, to fully exploit the multiscale similarities inside the LR input image, we accumulate the previous reconstruction results and their corresponding LR versions as additional example patches for the subsequent estimation process, and adopt a gradual magnification scheme to achieve the desired zooming size step by step. Extensive experiments on benchmark images have validated the effectiveness of the proposed method. Compared to other state-of-the-art SR approaches, the proposed method provides photorealistic HR images with sharp edges.

Hu, Jing; Luo, Yupin

2014-05-01

325

Tracking of In-111-labeled human umbilical tissue-derived cells (hUTC) in a rat model of cerebral ischemia using SPECT imaging  

PubMed Central

Background In order to increase understanding of how infused cells work, it becomes important to track their initial movement, localization, and engraftment efficiency following transplantation. However, the available in vivo cell tracking techniques are suboptimal. The study objective was to determine the biodistribution of intravenously administered Indium-111 (In-111) oxine labeled human umbilical tissue-derived cells (hUTC) in a rat model of transient middle cerebral occlusion (tMCAo) using single photon emission computed tomography (SPECT). Methods Rats received 3 million In-111 labeled hUTC (i.v.) 48?hrs after tMCAo. Following the administration of either hUTC or equivalent dose of In-111-oxine (18.5?MBq), animals underwent SPECT imaging on days 0, 1, and 3. Radioactivity in various organs as well as in the stroke area and contralateral hemisphere was determined, decay corrected and normalized to the total (whole body including head) radioactivity on day 0. Immunohistochemical analysis was also performed to confirm the beneficial effects of hUTC on vascular and synaptic density, and apoptosis. Results Most of the radioactivity (43.36±23.07% on day 0) trafficked to the lungs immediately following IV administration of In-111 labeled hUTC (day 0) and decreased drastically to 8.81±7.75 and 4.01±4.52% on days 1 and 3 post-injection, respectively. In contrast, radioactivity measured in the lung of animals that received In-111-oxine alone remained relatively unchanged from day 0 to day 1 (18.38±5.45% at day 0 to 12.59±5.94%) and decreased to 8.34±4.25% on day 3. Significantly higher radioactivity was observed in stroke areas of animals that received In-111 labeled hUTC indicating the presence of cells at the site of injury representing approximately 1% of total administered dose. In addition, there was significant increase in vascular and synaptophysin immunoreactivity in stroke areas of rats that received In-111 labeled hUTC. Conclusions The present studies showed the tracking of In-111 labeled hUTC to the sites of stroke in a rat model of tMCAo using SPECT. Animals treated with In-111 labeled hUTC showed histological improvements, with higher vascular and synaptic densities observed in the ischemic boundary zone (IBZ). PMID:23217090

2012-01-01

326

High dynamic range image acquisition using multiple images with different apertures  

NASA Astrophysics Data System (ADS)

The authors propose a method to obtain a high dynamic range (HDR) image from multiple images with different exposure. Unlike conventional methods that use multiple images with different shutter speeds, the proposed method takes multiple images with identical and short shutter speeds but with different apertures. Consequently, the input low dynamic range image is less affected by scene change, while it has undesirable defocus blur due to different depth of field. In order to mitigate defocus blur of input images with larger apertures, we estimate the defocus map of each input image and use it as the spatially variant point spread function to deblur the image. Then, we extract the weight maps of input images, which are used to combine them to synthesize an HDR image. Our experimental results show that the proposed algorithm produces high-quality HDR images using a small number (typically three) of input images.

Park, Tae Jang; Park, In Kyu

2012-12-01

327

Hadamard-like derivatives in Preisach modeling and control  

Microsoft Academic Search

We define a concept of derivatives of the relative boundary of the active set, on the Preisach plane, with respect to the time variable, under a time-varying input of the piecewise monotone type. These derivatives are related to the set-valued derivatives previously introduced by these authors. This concept of derivatives, which is akin to the derivatives introduced by Hadamard in

S. A. Belbas; I. D. Mayergoyz

2006-01-01

328

The application of cloud texture and motion derived from geostationary satellite images in rain estimation - a study on mid-latitude depressions  

Microsoft Academic Search

This paper presents the preliminary results of a rain rate estimation system that utilizes a combination of cloud appearance and motion that can be derived from Meteosat7. The proposed rain rate estimation system consists of three steps: feature selection, rain estimation and validation. In feature selection, cloud textural information is extracted and cloud motions are derived by a modified optical

Aimamorn Suvichakorn; Adrian Tatnall

2005-01-01

329

A new synthesis for terrestrial nitrogen inputs  

NASA Astrophysics Data System (ADS)

Nitrogen (N) inputs sustain many different aspects of local soil processes, their services, and their interactions with the broader Earth system. We present a new synthesis for terrestrial N inputs that considers both rock and atmospheric sources. We review evidence for state-factor regulation over biological N fixation, deposition and rock weathering inputs from local to global scales and in transient vs. steady-state landscapes. Our framework highlights strong organism and topographic (relief) controls over all three N input pathways, with the anthropogenic factor clearly important in rising N deposition rates. In addition, the climate, parent material and time factors are shown to influence patterns of fixation and rock-weathering inputs of N in diverse soil-systems. Data reanalysis suggests that weathering of N-rich parent material could resolve several known cases of "missing N inputs" in ecosystems, and demonstrates how the inclusion of rock N sources into modern concepts can lead to a richer understanding of spatial and temporal patterns of ecosystem N availability. For example, explicit consideration of rock N inputs into classic pedogenic models (e.g., Walker and Syers model) yields a fundamentally different expectation from the standard case: weathering of N-rich parent material could enhance N availability and facilitate terrestrial succession in developmentally young sites even in the absence of N-fixing organisms. We conclude that a state-factor framework for N complements our growing understanding multiple-source controls on phosphorus and cation availability in Earth's soil; but with significant exceptions given the lack of an N fixation analogue in all other biogeochemical cycles. Rather, a state-factor analysis of N must recognize non-symmetrical feedbacks among input pathways, whereby high N inputs via deposition or rock weathering have the potential to reduce biological fixation rates within a given state-factor.

Houlton, B. Z.; Morford, S. L.

2014-09-01

330

Quantum filtering for multiple input multiple output systems driven by arbitrary zero-mean jointly Gaussian input fields  

NASA Astrophysics Data System (ADS)

In this paper, we treat the quantum filtering problem for multiple input multiple output (MIMO) Markovian open quantum systems coupled to multiple boson fields in an arbitrary zero-mean jointly Gaussian state, using the reference probability approach formulated by Bouten and van Handel as a quantum version of a well-known method of the same name from classical nonlinear filtering theory, and exploiting the generalized Araki-Woods representation of Gough. This includes Gaussian field states such as vacuum, squeezed vacuum, thermal, and squeezed thermal states as special cases. The contribution is a derivation of the general quantum filtering equation (or stochastic master equation as they are known in the quantum optics community) in the full MIMO setup for any zero-mean jointly Gaussian input field states, up to some mild rank assumptions on certain matrices relating to the measurement vector.

Nurdin, H. I.

2014-07-01

331

Two-dimensional phase unwrapping using robust derivative estimation and adaptive integration.  

PubMed

The adaptive integration (ADI) method for two-dimensional (2-D) phase unwrapping is presented. The method uses an algorithm for noise robust estimation of partial derivatives, followed by a noise robust adaptive integration process. The ADI method can easily unwrap phase images with moderate noise levels, and the resulting images are congruent modulo 2pi with the observed, wrapped, input images. In a quantitative evaluation, both the ADI and the BLS methods (Strand et al.) were better than the least-squares methods of Ghiglia and Romero (GR), and of Marroquin and Rivera (MRM). In a qualitative evaluation, the ADI, the BLS, and a conjugate gradient version of the MRM method (MRMCG), were all compared using a synthetic image with shear, using 115 magnetic resonance images, and using 22 fiber-optic interferometry images. For the synthetic image and the interferometry images, the ADI method gave consistently visually better results than the other methods. For the MR images, the MRMCG method was best, and the ADI method second best. The ADI method was less sensitive to the mask definition and the block size than the BLS method, and successfully unwrapped images with shears that were not marked in the masks. The computational requirements of the ADI method for images of nonrectangular objects were comparable to only two iterations of many least-squares-based methods (e.g., GR). We believe the ADI method provides a powerful addition to the ensemble of tools available for 2-D phase unwrapping. PMID:18249691

Strand, Jarle; Taxt, Torfinn

2002-01-01

332

Generation of RTL verification input stimulus  

E-print Network

This thesis presents an approach for generating input stimulus for verification of register-transfer level (RTL) design of VLSI circuits. RTL design is often subjected to a significant verification effort due to errors introduced during manual...

Selvarathinam, Anand Manivannan

2012-06-07

333

7 CFR 3430.907 - Stakeholder input.  

Code of Federal Regulations, 2011 CFR

...Department of Agriculture (Continued) NATIONAL INSTITUTE OF FOOD AND AGRICULTURE COMPETITIVE AND NONCOMPETITIVE NON-FORMULA...forums (e.g., public meetings, requests for input and/or Web site), as well as through a notice in the Federal...

2011-01-01

334

7 CFR 3430.607 - Stakeholder input.  

Code of Federal Regulations, 2011 CFR

...Department of Agriculture (Continued) NATIONAL INSTITUTE OF FOOD AND AGRICULTURE COMPETITIVE AND NONCOMPETITIVE NON-FORMULA...forums (e.g., public meetings, request for input and/or via Web site), as well as through a notice in the Federal...

2011-01-01

335

Fingerprint Image Enhancement: Algorithm and Performance Evaluation  

Microsoft Academic Search

A critical step in automatic fingerprint matching is to automatically and reliably extract minutiae from the input fingerprint images. However, the performance of a minutiae extraction algorithm relies heavily on the quality of the input fingerprint images. In order to ensure that the performance of an automatic fingerprint identification\\/verification system will be robust with respect to the quality of input

Lin Hong; Yifei Wan; Anil K. Jain

1998-01-01

336

The GKS Input Model in MANIFOLD  

Microsoft Academic Search

This paper describes the specification of the GKS input model in MANIFOLD. The aim of the work reported in this paper was two-fold: first, to review the communication pat-terns implied by the GKS input model, and second, to evaluate the suitability of the MANIFOLD language as a tool for defining complex dynamic interaction patterns that are common in non-trivial user

Dirk Soede; Farhad Arbab; Ivan Herman; Paul J. W. Ten Hagen

1991-01-01

337

Proprioception: Peripheral Inputs and Perceptual Interactions  

Microsoft Academic Search

\\u000a Much emphasis has been placed on the specific role of specific inputs from muscle, joint and cutaneous afferents in the detection\\u000a of movement. However, particularly for the hand, multiple inputs from the moving part are likely to be important. This chapter\\u000a reviews some recent studies which examine the co-operative interaction between the various proprioceptive channels. Proprioceptive\\u000a control of movement must

Simon C. Gandevia; Kathyrn M. Refshauge; David F. Collins

338

Aggregate Input Output Models of Neuronal Populations  

PubMed Central

An extraordinary amount of electrophysiological data has been collected from various brain nuclei to help us understand how neural activity in one region influences another region. In this paper, we exploit the point process modeling (PPM) framework and describe a method for constructing aggregate input-output (IO) stochastic models that predict spiking activity of a population of neurons in the “output” region as a function of the spiking activity of a population of neurons in the “input” region. We first build PPMs of each output neuron as a function of all input neurons, and then cluster the output neurons using the model parameters. Output neurons that lie within the same cluster have the same functional dependence on the input neurons. We first applied our method to simulated data, and successfully uncovered the predetermined relationship between the two regions. We then applied our method to experimental data to understand the input-output relationship between motor cortical neurons and (i) somatosensory and (ii) premotor cortical neurons during a behavioral task. Our aggregate IO models highlighted interesting physiological dependencies including relative effects of inhibition/excitation from input neurons and extrinsic factors on output neurons. PMID:22552544

Saxena, Shreya; Schieber, Marc H.; Thakor, Nitish V.; Sarma, Sridevi V.

2014-01-01

339

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

340

Eur J Nucl Med Mol Imaging. Author manuscript Non-invasive estimation of hepatic blood perfusion from H2 15O PET  

E-print Network

perfusion from H2 15O PET images using tissue-derived arterial and portal input functions Kudomi Nobuyuki 1 Timo 2 , Knuuti Juhani 1 , Iida Hirokazu 3 , Nuutila Pirjo 1 4 , Iozzo Patricia 1 5 Turku PET Centre1 artery. When its perfusion is assessed using PET and O-labeled water15 (H O), calculations require a dual

Paris-Sud XI, Université de

341

A novel method to derive separate gray and white matter cerebral blood flow measures from MR imaging of acute ischemic stroke patients  

Microsoft Academic Search

Perfusion-weighted imaging (PWI) measures can predict tissue outcome in acute ischemic stroke. Accuracy might be improved if differential tissue susceptibility to ischemia is considered. We present a novel voxel-by-voxel analysis to characterize cerebral blood flow (CBF) separately in gray (GM) and white matter (WM). Ten patients were scanned with inversion-recovery spin-echo EPI (IRSEPI), diffusion-weighted imaging (DWI), PWI<6 h from onset

Jessica E Simon; Michael S Bristow; Hong Lu; M Louis Lauzon; Robert A Brown; José V Manjón; Michael Eliasziw; Richard Frayne; Alastair M Buchan; Andrew M Demchuk; J Ross Mitchell; R Mitchell

2005-01-01

342

Syntheses of 2-nitroimidazole derivatives conjugated with 1,4,7-triazacyclononane-N,N'-diacetic acid labeled with F-18 using an aluminum complex method for hypoxia imaging.  

PubMed

Hypoxia imaging is important for diagnosis of ischemic diseases, and thus various (18)F-labeled radiopharmaceuticals have been developed. However, (18)F-labeling requires multistep procedures including azeotropic distillation, which is complicated and difficult to automate. Recently, (18)F-labeling method using Al-F complex in aqueous solution was devised that offered a straightforward (18)F-labeling procedure. We synthesized nitroimidazole derivatives conjugated with 1,4,7-triazacyclononane-1,4-diacetic acid (NODA) that can be labeled with (18)F using Al-F complex and examined their radiochemistries, in vitro and in vivo biological properties, and animal PET imaging characteristics. We found that the synthesized derivatives have excellent (18)F-labeling efficiencies, high stabilities, specific uptakes in cultured hypoxic tumor cells, and high tumor to nontumor ratios in xenografted mice. Furthermore, the derivatives were labeled with (18)F in a straightforward manner within 15 min at high labeling efficiencies and radiochemical purities. In conclusion, (18)F-labeled NODA-nitroimidazole conjugates were developed and proved to be promising hypoxia PET agents. PMID:22443100

Hoigebazar, Lathika; Jeong, Jae Min; Lee, Ji-Youn; Shetty, Dinesh; Yang, Bo Yeun; Lee, Yun-Sang; Lee, Dong Soo; Chung, June-Key; Lee, Myung Chul

2012-04-12

343

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

344

A comparison of rat SPECT images obtained using 99mTc derived from 99Mo produced by an electron accelerator with that from a reactor  

NASA Astrophysics Data System (ADS)

Recent shortages of molybdenum-99 (99Mo) have led to an examination of alternate production methods that could contribute to a more robust supply. An electron accelerator and the photoneutron reaction were used to produce 99Mo from which technetium-99m (99mTc) is extracted. SPECT images of rat anatomy obtained using the accelerator-produced 99mTc with those obtained using 99mTc from a commercial generator were compared. Disks of 100Mo were irradiated with x-rays produced by a 35 MeV electron beam to generate about 1110 MBq (30 mCi) of 99Mo per disk. After target dissolution, a NorthStar ARSII unit was used to separate the 99mTc, which was subsequently used to tag pharmaceuticals suitable for cardiac and bone imaging. SPECT images were acquired for three rats and compared to images for the same three rats obtained using 99mTc from a standard reactor 99Mo generator. The efficiency of 99Mo-99mTc separation was typically greater than 90%. This study demonstrated the delivery of 99mTc from the end of beam to the end user of approximately 30 h. Images obtained using the heart and bone scanning agents using reactor and linac-produced 99mTc were comparable. High-power electron accelerators are an attractive option for producing 99Mo on a national scale.

Galea, R.; Wells, R. G.; Ross, C. K.; Lockwood, J.; Moore, K.; Harvey, J. T.; Isensee, G. H.

2013-05-01

345

Shallow sea-floor reflectance and water depth derived by unmixing multispectral imagery  

SciTech Connect

A major problem for mapping shallow water zones by the analysis of remotely sensed data is that contrast effects due to water depth obscure and distort the special nature of the substrate. This paper outlines a new method which unmixes the exponential influence of depth in each pixel by employing a mathematical constraint. This leaves a multispectral residual which represents relative substrate reflectance. Input to the process are the raw multispectral data and water attenuation coefficients derived by the co-analysis of known bathymetry and remotely sensed data. Outputs are substrate-reflectance images corresponding to the input bands and a greyscale depth image. The method has been applied in the analysis of Landsat TM data at Hamelin Pool in Shark Bay, Western Australia. Algorithm derived substrate reflectance images for Landsat TM bands 1, 2, and 3 combined in color represent the optimum enhancement for mapping or classifying substrate types. As a result, this color image successfully delineated features, which were obscured in the raw data, such as the distributions of sea-grasses, microbial mats, and sandy area. 19 refs.

Bierwirth, P.N.; Lee, T.J.; Burne, R.V. (Marine Spill Response Corp., Washington, DC (United States) Michigan Environmental Research Inst., Ann Arbor (United States))

1993-03-01

346

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

347

The computational complexity of matching an input fingerprint against every entry in a large-scale fingerprint  

E-print Network

1 Abstract The computational complexity of matching an input fingerprint against every entry in a large-scale fingerprint database can be prohibitive. In fingerprint indexing, a small set of candidate fingerprints is selected from the database and only images in this set are compared against the input probe

Ross, Arun Abraham

348

Wiimote as an Input Device in Google Earth Visualization and Navigation: A User Study Comparing Two Alternatives  

Microsoft Academic Search

This paper presents a user study performed to compare the usability of the Wiimote as an input device to visualize information and navigate in Google Earth using two different configurations. This study had the collaboration of 15 participants which performed a set of tasks using the Wiimote as an input device while the image was projected on a common projection

Beatriz Sousa Santos; Bruno Prada; Hugo Ribeiro; Paulo Dias; Samuel S. Silva; Carlos Ferreira

2010-01-01

349

An Image Completion Algorithm Using Occlusion-Free Images from Internet Photo Sharing Sites  

NASA Astrophysics Data System (ADS)

In this paper, we propose an image completion algorithm which takes advantage of the countless number of images available on Internet photo sharing sites to replace occlusions in an input image. The algorithm 1) automatically selects the most suitable images from a database of downloaded images and 2) seamlessly completes the input image using the selected images with minimal user intervention. Experimental results on input images captured at various locations and scene conditions demonstrate the effectiveness of the proposed technique in seamlessly reconstructing user-defined occlusions.

Amirshahi, Hanieh; Kondo, Satoshi; Ito, Koichi; Aoki, Takafumi

350

Staring 2-D hadamard transform spectral imager  

DOEpatents

A staring imaging system inputs a 2D spatial image containing multi-frequency spectral information. This image is encoded in one dimension of the image with a cyclic Hadamarid S-matrix. The resulting image is detecting with a spatial 2D detector; and a computer applies a Hadamard transform to recover the encoded image.

Gentry, Stephen M. (Albuquerque, NM); Wehlburg, Christine M. (Albuquerque, NM); Wehlburg, Joseph C. (Albuquerque, NM); Smith, Mark W. (Albuquerque, NM); Smith, Jody L. (Albuquerque, NM)

2006-02-07

351

Image Fusion Quality Metrics by Directional Projection  

Microsoft Academic Search

Image fusion has been over-studied recently. Nevertheless, few works aim to how to evaluate the performance of image fusion algorithms. In this paper, we extend the work in image quality evaluation to a novel metric for objective evaluation of image fusion. Firstly the input images and the result image are converted into local sensitive intensity (LSI) by Radon transform. Then

Richang Hong; Yan Song; Jinhui Tang; Jianxin Pang

2009-01-01

352

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

353

Squiggle - A Glyph Recognizer for Gesture Input  

E-print Network

Squiggle is a template-based glyph recognizer in the lineage of `$1 Recognizer' and `Protractor'. It seeks a good fit linear affine mapping between the input and template glyphs which are represented as a list of milestone points along the glyph path. The algorithm can recognize input glyphs invariant of rotation, scaling, skew, and reflection symmetries. In practice the algorithm is fast and robust enough to recognize user-generated glyphs as they are being drawn in real time, and to project `shadows' of the matching templates as feedback.

Lee, Jeremy

2011-01-01

354

Input/Output Subroutine Library Program  

NASA Technical Reports Server (NTRS)

Efficient, easy-to-use program moved easily to different computers. Purpose of NAVIO, Input/Output Subroutine Library, provides input/output package of software for FORTRAN programs that is portable, efficient, and easy to use. Implemented as hierarchy of libraries. At bottom is very small library containing only non-portable routines called "I/O Kernel." Design makes NAVIO easy to move from one computer to another, by simply changing kernel. NAVIO appropriate for software system of almost any size wherein different programs communicate through files.

Collier, James B.

1988-01-01

355

Desert dust aerosol air mass mapping in the western Sahara, using particle properties derived from space-based multi-angle imaging  

Microsoft Academic Search

ABSTRACT Coincident observations made over the Moroccan desert during the Sahara mineral dust experiment (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from multi-angle imaging spectroradiometer (MISR) observations, and to place the suborbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days during which coincident observations were made, MISR mid-visible

Ralph Kahn; Andreas Petzold; Manfred Wendisch; Eike Bierwirth; Tilman Dinter; Michael Esselborn; Marcus Fiebig; Birgit Heese; Peter Knippertz; Detlef Müller; Alexander Schladitz; Wolfgang von Hoyningen-Huene

2009-01-01

356

Desert dust aerosol air mass mapping in the western Sahara, using particle properties derived from space-based multi-angle imaging  

Microsoft Academic Search

Coincident observations made over the Moroccan desert during the Sahara mineral dust experiment (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from multi-angle imaging spectroradiometer (MISR) observations, and to place the suborbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days during which coincident observations were made, MISR mid-visible aerosol

RALPH K AHN; P ETZOLD; M A NFRED; W E NDISCH; E IKE B IERW; M ICHAEL E SSELBORN; M A RCUS; F IEBIG; PETER K NIPPERTZ; A LEXANDER

2009-01-01

357

DESIGN AND IMPLEMENTATION OF TIME-OPTIMAL NEGATIVE INPUT SHAPERS  

Microsoft Academic Search

Input shaping is a method for reducing residual vibrations in computer controlled machines. Vibration is eliminated by convolving a sequence of impulses, an input shaper, with a desired system command to produce a shaped input. The shaped input is then used to drive the system. The input shaper has traditionally contained only positively valued impulses. However, when the impulses are

William E. Singhose; Neil C. Singer; Warren P. Seering

358

An advanced image fusion algorithm based on wavelet transform: incorporation with PCA and morphological processing  

NASA Astrophysics Data System (ADS)

There are numerous applications for image fusion, some of which include medical imaging, remote sensing, nighttime operations and multi-spectral imaging. In general, the discrete wavelet transform (DWT) and various pyramids (such as Laplacian, ratio, contrast, gradient and morphological pyramids) are the most common and effective methods. For quantitative evaluation of the quality of fused imagery, the root mean square error (RMSE) is the most suitable measure of quality if there is a "ground truth" image available; otherwise, the entropy, spatial frequency or image quality index of the input images and the fused images can be calculated and compared. Here, after analyzing the pyramids" performance with the four measures mentioned, an advanced wavelet transform (aDWT) method that incorporates principal component analysis (PCA) and morphological processing into a regular DWT fusion algorithm is presented. Specifically, at each scale of the wavelet transformed images, a principle vector was derived from two input images and then applied to two of the images" approximation coefficients (i.e., they were fused by using the principal eigenvector). For the detail coefficients (i.e., three quarters of the coefficients), the larger absolute values were chosen and subjected to a neighborhood morphological processing procedure which served to verify the selected pixels by using a "filling" and "cleaning" operation (this operation filled or removed isolated pixels in a 3-by-3 local region). The fusion performance of the advanced DWT (aDWT) method proposed here was compared with six other common methods, and, based on the four quantitative measures, was found to perform the best when tested on the four input image types. Since the different image sources used here varied with respect to intensity, contrast, noise, and intrinsic characteristics, the aDWT is a promising image fusion procedure for inhomogeneous imagery.

Zheng, Yufeng; Essock, Edward A.; Hansen, Bruce C.

2004-05-01

359

Edge Detection Discrete approx. of a derivative  

E-print Network

Edge Detection #12;· Discrete approx. of a derivative · Threshold the derivative image · Second derivative, zero crossing detect ­ Weak edges (gradual variation) detected better, less chance of multiple edge responses · Derivative: enhances noise · Band-pass filtering: some smoothing followed

Vaswani, Namrata

360

Derivation of formulas for root-mean-square errors in location, orientation, and shape in triangulation solution of an elongated object in space  

NASA Technical Reports Server (NTRS)

Formulas are derived for the root-mean-square (rms) displacement, slope, and curvature errors in an azimuth-elevation image trace of an elongated object in space, as functions of the number and spacing of the input data points and the rms elevation error in the individual input data points from a single observation station. Also, formulas are derived for the total rms displacement, slope, and curvature error vectors in the triangulation solution of an elongated object in space due to the rms displacement, slope, and curvature errors, respectively, in the azimuth-elevation image traces from different observation stations. The total rms displacement, slope, and curvature error vectors provide useful measure numbers for determining the relative merits of two or more different triangulation procedures applicable to elongated objects in space.

Long, S. A. T.

1974-01-01

361

Fusion engines for multimodal input: a survey  

Microsoft Academic Search

Fusion engines are fundamental components of multimodal inter-active systems, to interpret input streams whose meaning can vary according to the context, task, user and time. Other surveys have considered multimodal interactive systems; we focus more closely on the design, specification, construction and evaluation of fusion engines. We first introduce some terminology and set out the major challenges that fusion engines

Denis Lalanne; Laurence Nigay; Philippe A. Palanque; Peter Robinson; Jean Vanderdonckt; Jean-françois Ladry

2009-01-01

362

The chromatic input to global motion perception  

Microsoft Academic Search

For over 30 years there has been a controversy over whether color-defined motion can be perceived by the human visual system. Some results suggest that there is no chromatic motion mechanism at all, whereas others do find evidence for a purely chromatic motion mechanism. Here we examine the chromatic input to global motion processing for a range of color directions

ALEXA I. RUPPERTSBERG; SOPHIE M. WUERGER; MARCO BERTAMINI

2003-01-01

363

Sensor networks as video game input devices  

Microsoft Academic Search

In this work we are motivated by creating a network of sensors that can be used as input devices for video games. Our goal is to create an inexpensive network of off-the-shelf sensors that are used to force proper movement and engagement of the player. Our experience shows that a distributed set of sensors around the body prevents the player

Anthony Whitehead; Nick Crampton; Kaitlyn Fox; Hannah Johnston

2007-01-01

364

Effective Input Variable Selection for Function Approximation  

E-print Network

subset of variables that are usually obtained by linear or nonlinear transformations of the original ones (feature extraction or input variable extraction). This paper deals with filter methods for feature selection. Filter methods have the great advantage that the model has no influence on the selected variables

Verleysen, Michel

365

Instrumentation for measuring energy inputs to implements  

SciTech Connect

A microcomputer-based instrumentation system for monitoring tractor operating parameters and energy inputs to implements was developed and mounted on a 75-power-takeoff-KW tractor. The instrumentation system, including sensors and data handling equipment, is discussed. 10 refs.

Tompkins, F.D.; Wilhelm, L.R.

1981-01-01

366

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

367

Student Input in College Decision Making  

ERIC Educational Resources Information Center

Engaging students in making decisions, especially those that directly impact student life, benefits the institution and the students themselves. Students are often asked to evaluate faculty, courses, campus services, and their overall college experience, but their opinions are more rarely solicited for input about new institutional initiatives.…

Schwartz, Celeste M.; Craig, Emory M.; Trzeciak, Jeff; Little, Julie K.; Diaz, Veronica

2008-01-01

368

SWAT 2012 Input/Output Documentation  

E-print Network

The Soil and Water Assessment Tool (SWAT) is a comprehensive model that requires a diversity of information in order to run. Novice users may feel overwhelmed by the variety and number of inputs when they first begin to use the model. This document...

Arnold, J.G.; Kiniry, J.R.; Srinivasan, R.; Williams, J.R.; Haney, E.B.; Neitsch, S.L.

2013-03-04

369

Optimum Input Leads for Cryogenic Apparatus  

Microsoft Academic Search

Electrical leads carrying currents into cryogenic apparatus also introduce heat. Even with an ideal Carnot cycle, the mechanical power needed to remove this heat can be one hundred or more times the heat flow itself. If the currents and hence the input leads are heavy, a very sizeable refrigerator may be required. In this article the configuration of the leads

Richard McFee

1959-01-01

370

Univariate input models for stochastic simulation  

Microsoft Academic Search

Techniques are presented for modeling and randomly sampling many of the multivariate probabilistic input processes that drive discrete-event simulation experiments. Emphasis is given to bivariate and trivariate extensions of the univariate beta, Johnson, and Bézier dist ribution families because of the flexibility of these families to model a wide range of shapes for the marginal distributions while also representing the

Michael E. Kuhl; Julie S. Ivy; Emily K. Lada; Natalie M. Steiger; Mary Ann Flanigan Wagner; James R. Wilson

2010-01-01

371

Programmable Input for Nanomagnetic Logic Devices  

NASA Astrophysics Data System (ADS)

A programmable magnetic input, based on the magnetic interaction of a soft and hard magnetic layer is presented for the ?rst time. Therefore, a single-domain Co/Pt nanomagnet is placed on top of one end of a permalloy bar, separated by a thin dielectric layer. The permalloy bar of the introduced input structure is magnetized by weak easy-axis in-plane ?elds. Acting like a 'magnetic ampli?er', the generated fringing ?elds of the permalloy pole are strong enough to control the magnetization of the superimposed Co/Pt nanomagnets, which have high crystalline perpendicular magnetic anisotropy. This magnetostatic interaction results in a shift of the hysteresis curve of the Co/Pt nanomagnet, measured by magneto-optical Kerr microscopy. The Co/Pt nanomagnet is ?xed by the fringing ?eld of the permalloy and thereby not affected by the magnetic power clock of the Nanomagnetic Logic system. MFM measurements verify the functionality of the programmable magnetic input structure. The fringing ?elds are extracted from micromagnetic simulations and are in good agreement with experimental results. The introduced input structure enables switching the logic functionality of the majority gate from NAND to NOR during runtime, offering programmable Nanomagnetic Logic.

Kiermaier, J.; Breitkreutz, S.; Eichwald, I.; Ju, X.; Csaba, G.; Schmitt-Landsiedel, D.; Becherer, M.

2013-01-01

372

Hydrogen Generation Rate Model Calculation Input Data  

SciTech Connect

This report documents the procedures and techniques utilized in the collection and analysis of analyte input data values in support of the flammable gas hazard safety analyses. This document represents the analyses of data current at the time of its writing and does not account for data available since then.

KUFAHL, M.A.

2000-04-27

373

Regulation of cough by secondary sensory inputs  

Microsoft Academic Search

We have reviewed the role of afferent inputs and blood chemical changes to the central nervous system, and the way in which they modify the cough and expiration reflexes (CR and ER). Slowly adapting pulmonary stretch receptors (SARs) augment the CR, insofar as when their activity is abolished the CRs from the tracheobronchial (TB) tree and larynx are abolished or

Jan Hanacek; Milos Tatar; John Widdicombe

2006-01-01

374

Selecting training inputs via greedy rank covering  

SciTech Connect

We present a general method for selecting a small set of training inputs, the observations of which will suffice to estimate the parameters of a given linear model. We exemplify the algorithm in terms of predicting segmental duration of phonetic-segment feature vectors in a text-to-speech synthesizer, but the algorithm will work for any linear model and its associated domain.

Buchsbaum, A.L.; Santen, J.P.H. van [AT& T Bell Laboratories, Murray Hill, NJ (United States)

1996-12-31

375

Neuronal Models with Current Inputs Jianfeng Feng  

E-print Network

a superposition of `colored' and `white' noise to approximate current inputs in neural models. Numerical results of EPSPs and IPSPs affect the output of a single neuron model­the integrate-and-fire model and the Hodgkin the mean of interspike intervals (ISIs) of efferent spike trains of the integrate-and-fire model

Feng, Jianfeng

376

Input to Priorities Panel August 7, 2012  

E-print Network

Input to Priorities Panel August 7, 2012 Jeff Freidberg MIT 1 #12;The Emperor of Fusion has · Comparison (1 GW overnight cost) · Coal $ 3B · Gas $ 1B · Nuclear $ 4B · Wind $ 2B · Solar-T $ 3B · ITER $25B

377

Pricing Access to a Monopoly Input  

Microsoft Academic Search

What price should downstream entrants pay a vertically integrated incumbent monopoly for use of its assets? Courts, legislators, and regulators have at times mandated that incumbent monopolies lease assets required for the production of a retail service to entrants in efforts to increase the competitiveness of retail markets. This pa- per compares two rules for pricing such monopoly inputs: marginal

David S. Sibley; Michael J. Doane; Michael A. Williams

2003-01-01

378

Pricing Access to a Monopoly Input  

Microsoft Academic Search

What price should downstream entrants pay a vertically integrated incumbent monopoly for use of its assets? Courts, legislators, and regulators have at times mandated that incumbent monopolies lease assets required for the production of a retail service to entrants in efforts to increase the competitiveness of retail markets. This paper compares two rules for pricing such monopoly inputs: marginal cost

David S. Sibley; Michael J. Doane; Michael A. Williams; Shu-Yi Tsai

2004-01-01

379

DO MODEL UNCERTAINTY WITH CORRELATED INPUTS  

EPA Science Inventory

The effect of correlation among the input parameters and variables on the output uncertainty of the Streeter-Phelps water quality model is examined. hree uncertainty analysis techniques are used: sensitivity analysis, first-order error analysis, and Monte Carlo simulation. odifie...

380

Module 14: Low Input Ag Models  

NSDL National Science Digital Library

Eastern Iowa Community College provides this learning module to teach students topics related to low input agricultural models such as current issues in development, grid issues, and energy efficiency. Users can download a zip file in which they will find a syllabus, student handouts, a quiz, and 75 slide PowerPoint presentation.

2014-08-29

381

Cumulative input function method for linear compartmental models and spectral analysis in PET  

PubMed Central

Compartmental modeling and spectral analysis are often used for tracer kinetic modeling in positron emission tomography (PET). The concentrations in kinetic equations are usually considered to be instantaneous, whereas PET data are inherently integrated over time, which leads to uncertainties in the results. A new formalism for kinetic analysis that uses cumulative tracer concentrations and avoids approximating the image-derived input function and PET measurements with midframe instantanous values was developed. We assessed the improvements of the new formalism over the midframe approximation methods for three commonly used radiopharmaceuticals: [11C]raclopride, 2?-deoxy-2?-[18F]fluoro--glucose (FDG), and 3?-deoxy-3?-[18F]fluoro-thymidine (FLT). We found that improvements are case dependent and often not negligible. Improvements for determination of binding potential for [11C]raclopride ranged from 5% to 25%. Improvements in estimation accuracy of FDG and FLT microparameters ranged up to 25%. On the other hand, estimation of macroparameter Ki=K1k3/(k2+k3) for FDG or FLT did not show significant benefit with the new method; only modest improvement up to 2% was observed. Assessment of the benefits of using new method is far from being exhaustive, but possibly significant improvement was demonstrated. Therefore, we consider the proposed algorithm a necessary component of any kinetic analysis software. PMID:20808319

Simoncic, Urban; Jeraj, Robert

2011-01-01

382

Operational life prediction on gating image intensifier  

NASA Astrophysics Data System (ADS)

Operational life is one of the important parameters to evaluate second and super second generation image intensifiers. It can be used not only to monitor manufacturing technique in product line, then the technology on photocathode processing, MCP degassing and MCP producing can be adjusted promptly, but also to eliminate the image intensifiers which have hidden risk on operational life as early as possible. Recently gating image intensifiers are used widely, method to estimate the operational life of gating image intensifier related to its practical operate mode and working condition need to be established urgently. The least square method to analyze the operational life test data in product line was introduced in this paper. Now the data can be analyzed with convenient statistic analyze function on Excel. Using "worksheet function" and "chart wizard" and "data analysis" on Excel to do the least square method calculation, spreadsheets are established to do complex data calculation with worksheet functions. Based on them, formulas to monitor the technology parameters were derived, and the conclusion that the operational life was only related to the decrease slope of photocathode exponential fit curve was made. The decrease slope of photocathode sensitivity exponential fit curve and the decrease percent of the exponential fit photocathode sensitivity can be used to evaluate the qualification of the operational life rapidly. The mathematic models for operational life prediction on image intensifier and gating image intensifier are established respectively based on the acceptable values of the decrease percent of the exponential fit photocathode sensitivity and the expecting signal to noise ratio. The equations predicting the operational life related to duty cycle and input light level on gating image intensifier were derived, and the relationship between them were discussed too. The theory foundation were made herein, so the user can select proper gating image intensifier type just considering the practical using condition and make the best design and application project. The paper gave guidance on data analyzing in product line and using gating image intensifier.

Dong, Yu-hui; Shen, Zhi-guo; Li, Zhong-li

2009-07-01

383

Synthesis and evaluation of a 125I-labeled iminodihydroquinoline-derived tracer for imaging of voltage-gated sodium channels?  

PubMed Central

In vivo imaging of voltage-gated sodium channels (VGSCs) can potentially provide insights into the activation of neuronal pathways and aid the diagnosis of a number of neurological diseases. The iminodihydroquinoline WIN17317-3 is one of the most potent sodium channel blockers reported to date and binds with high affinity to VGSCs throughout the rat brain. We have synthesized a 125I-labeled analogue of WIN17317-3 and evaluated the potential of the tracer for imaging of VGSCs with SPECT. Automated patch clamp studies with CHO cells expressing the Nav1.2 isoform and displacement studies with [3H]BTX yielded comparable results for the non-radioactive iodinated iminodihydroquinoline and WIN17317-3. However, the 125I-labeled tracer was rapidly metabolized in vivo, and suffered from low brain uptake and high accumulation of radioactivity in the intestines. The results suggest that iminodihydroquinolines are poorly suited for tracer development. PMID:23910595

Perez-Medina, Carlos; Patel, Niral; Robson, Mathew; Lythgoe, Mark F.; Arstad, Erik

2013-01-01

384

Influences of urbanization on surface characteristics as derived from the Moderate-Resolution Imaging Spectroradiometer: A case study for the Beijing metropolitan area  

Microsoft Academic Search

Moderate-Resolution Imaging Spectroradiometer (MODIS) global land surface temperature\\/emissivity (LST), vegetation indices, BRDF\\/Albedo and land cover products collected for the period of March 2000 to March 2006 are combined with the surface heat fluxes retrieved from MODIS as well as meteorological data to investigate the influence of urbanization associated with the surface characteristics of the city of Beijing. The results show

Kaicun Wang; Jiankai Wang; Pucai Wang; Michael Sparrow; Juan Yang; Hongbin Chen

2007-01-01

385

Quantum limits on noise in dual input-output linear optical amplifiers and attenuators  

SciTech Connect

The input-output relations for linear amplifiers and attenuators that have two input and two output channels are used to derive inequalities that relate their gain profiles and output noise spectra. The results generalize earlier derivations, which mainly focus their attention on single-channel devices, to the two-ended amplifiers and attenuators often used in practical communications systems. The present inequalities are satisfied by the results of previous calculations for specific model systems. It is shown that; in contrast to single-channel devices, a two-ended system can act as an amplifier for some input signals and an attenuator for others, even when all the signal frequencies are the same. The output from the two-channel amplifier has a minimum noise determined by the sum of the gains for both input channels, even when only one input channel is used and the other is in its vacuum state. The conditions on device construction needed to achieve equal gains for signals that arrive at the two ends of the device are determined. The present results reduce to those of single-channel theory in special cases where the two output channels are each separately fed by only one of the two input channels.

Loudon, Rodney; Jedrkiewicz, Ottavia [Department of Electronic Systems Engineering, University of Essex, Colchester CO4 3SQ (United Kingdom); Barnett, Stephen M.; Jeffers, John [Department of Physics, University of Strathclyde, Glasgow G4 0NG, Scotland (United Kingdom)

2003-03-01

386

Patch-based near-optimal image denoising.  

PubMed

In this paper, we propose a denoising method motivated by our previous analysis of the performance bounds for image denoising. Insights from that study are used here to derive a high-performance practical denoising algorithm. We propose a patch-based Wiener filter that exploits patch redundancy for image denoising. Our framework uses both geometrically and photometrically similar patches to estimate the different filter parameters. We describe how these parameters can be accurately estimated directly from the input noisy image. Our denoising approach, designed for near-optimal performance (in the mean-squared error sense), has a sound statistical foundation that is analyzed in detail. The performance of our approach is experimentally verified on a variety of images and noise levels. The results presented here demonstrate that our proposed method is on par or exceeding the current state of the art, both visually and quantitatively. PMID:22020683

Chatterjee, Priyam; Milanfar, Peyman

2012-04-01

387

Multi-input square iterative learning control with input rate limits and bounds.  

PubMed

We present a simple modification of the iterative learning control algorithm of Arimoto et al. (1984) for the case where the inputs are bounded and time-rate-limited. The Jacobian error condition for monotonicity of input-error, rather than output-error, norms, is specified, the latter being insufficient to assure convergence, as proved herein. To the best of our knowledge, these facts have not been previously pointed out in the iterative learning control literature. We present a new proof that the modified controller produces monotonically decreasing input error norms, with a norm that covers the entire time interval of a learning trial. PMID:18238150

Driessen, B J; Sadegh, N

2002-01-01

388

Using digital image processing to characterize the Campbell-Stokes sunshine recorder and to derive high-temporal resolution direct solar irradiance  

NASA Astrophysics Data System (ADS)

The Campbell-Stokes sunshine recorder (CSSR) has been one of the most commonly used instruments for measuring sunshine duration (SD) through the burn length of a given CSSR card. Many authors have used SD to obtain information about cloudiness and solar radiation (by using Ångström-Prescott type formulas). Contrarily, the burn width has not been used systematically. In principle, the burn width increases for increasing direct beam irradiance. The aim of this research is to show the relationship between burn width and direct solar irradiance (DSI), and to prove whether this relationship depends on the type of CSSR and burning card. A semi-automatic method based on image processing of digital scanned images of burnt cards is presented. With this method, the temporal evolution of the burn width with 1 min resolution can be obtained. From this, SD is easily calculated and compared with the traditional (i.e. visual) determination. The method tends to slightly overestimate SD but the thresholds that are used in the image processing could be adjusted to obtain an unbiased estimation. Regarding the burn width, results show that there is a high correlation between two different models of CSSRs, as well as a strong relationship between burn widths and DSI at a high-temporal resolution. Thus, for example, hourly DSI may be estimated from the burn width with higher accuracy than based on burn length (for one of the CSSR, relative root mean squared error 24 and 30% respectively; mean bias error -0.6 and -30.0 W m-2 respectively). The method offers a practical way to exploit long-term sets of CSSR cards to create long time series of DSI. Since DSI is affected by atmospheric aerosol content, CSSR records may also become a proxy measurement for turbidity and atmospheric aerosol loading.

Sanchez-Romero, A.; González, J. A.; Calbó, J.; Sanchez-Lorenzo, A.

2014-09-01

389

Input on NIH Toolbox inclusion criteria  

PubMed Central

Objective: The NIH Toolbox is intended to be responsive to the needs of investigators evaluating neurologic and behavioral function in diverse settings. Early phases of the project involved gathering information and input from potential end users. Methods: Information was collected through literature and instrument database reviews, requests for information, consensus meetings, and expert interviews and integrated into the NIH Toolbox development process in an iterative manner. Results: Criteria for instrument inclusion, subdomains to be assessed, and preferences regarding instrument cost and length were obtained. Existing measures suitable for inclusion in the NIH Toolbox and areas requiring new measure development were identified. Conclusion: The NIH Toolbox was developed with explicit input from potential end users regarding many of its key features. PMID:23479548

Victorson, David; Debb, Scott M.; Gershon, Richard C.

2013-01-01

390

Forest Floor Decomposition Following Hurricane Litter Inputs in Several Puerto Rican Forests  

Microsoft Academic Search

Hurricanes affect ecosystem processes by altering resource availability and heterogeneity, but the spatial and temporal signatures of these events on biomass and nutrient cycling processes are not well understood. We examined mass and nutrient inputs of hurricane-derived litter in six tropical forests spanning three life zones in northeastern Puerto Rico after the passage of Hurricane Georges. We then followed the

Rebecca Ostertag; Frederick N. Scatena; Whendee L. Silver

2003-01-01

391

Chandrasekhar equations for infinite dimensional systems. Part 2: Unbounded input and output case  

NASA Technical Reports Server (NTRS)

A set of equations known as Chandrasekhar equations arising in the linear quadratic optimal control problem is considered. In this paper, we consider the linear time-invariant system defined in Hilbert spaces involving unbounded input and output operators. For a general class of such systems, the Chandrasekhar equations are derived and the existence, uniqueness, and regularity of the results of their solutions established.

Ito, Kazufumi; Powers, Robert K.

1987-01-01

392

A Practical Approach for Analysis of Input and Output Impedances of Feedback Amplifiers  

ERIC Educational Resources Information Center

This paper suggests a pedagogical approach to teaching the subject of the analysis of feedback amplifiers for electrical engineering students at the undergraduate level. Special attention is given to derivation of the input and output impedances. In order to make the procedure clear and suitable for classroom presentation an alternative proof of…

Abramovitz, A.

2009-01-01

393

Finite time observation of nonlinear time-delay systems with unknown inputs  

E-print Network

Finite time observation of nonlinear time-delay systems with unknown inputs G. Zheng J.-P. Barbot in this paper for nonlinear time- delay systems. By extending the Lie derivative for time-delay systems, unlike nonlinear systems without delays, the analysis of properties for time-delay system is more com

Paris-Sud XI, Université de

394

Environmental Input - Output Multipliers in Greece: The Impact of Technological Change (1988-1998)  

Microsoft Academic Search

The paper derives measures of environmental emissions related to economic activity in Greece for the year 2000, utilizing the environmental input-output framework. Alternatively, two different technical coefficients matrices, i.e. for the years 1988 and 1998 respectively, are used for the calculations concerning year 2000. The difference observed in the results originates in technological change and is expressed directly through each

ATHENA BELEGRI-ROBOLI; MARIA MARKAKI; PANAYOTIS MICHAELIDES

395

Investigation of Effects of Varying Model Inputs on Mercury Deposition Estimates in the Southwest US  

EPA Science Inventory

The Community Multiscale Air Quality (CMAQ) model version 4.7.1 was used to simulate mercury wet and dry deposition for a domain covering the continental United States (US). The simulations used MM5-derived meteorological input fields and the US Environmental Protection Agency (E...

396

Robust Residual Generation Using Unknown Input Observers  

Microsoft Academic Search

\\u000a The generation of robust residuals is the most important task in model-based fault diagnosis techniques. As pointed out in\\u000a Section 2.11, the disturbance de-coupling based approaches are the dominant approaches for robust residual generation. For\\u000a those approaches, uncertain factors in system modeling are considered to act via an unknown input (or disturbance) on a linear\\u000a system model. Although the unknown

Jie Chen; Ron J. Patton

397

Solar wind-magnetosphere energy input functions  

Microsoft Academic Search

A new formula for the solar wind-magnetosphere energy input parameter, P\\/sub i\\/, is sought by applying the constraints imposed by dimensional analysis. Applying these constraints yields a general equation for P\\/sub i\\/ which is equal to rho V³l\\/sub CF\\/²F(M\\/sub A\\/,theta) where, rho V³ is the solar wind kinetic energy density and l\\/sub CF\\/² is the scale size of the magnetosphere's

L. F. Bargatze; R. L. McPherron; D. N. Baker

1985-01-01

398

Generalized Input-Output Inequality Systems  

Microsoft Academic Search

In this paper two types of generalized Leontief input-output inequality systems are introduced. The minimax properties for\\u000a a class of functions associated with the\\u000a inequalities are studied. Sufficient and necessary conditions for the inequality systems to have solutions are obtained in\\u000a terms of the minimax value. Stability analysis for the solution set is provided in terms of upper semi-continuity and

Yingfan Liu; Qinghong Zhang

2006-01-01

399

[Input and output channels of quantum biocomputers].  

PubMed

It is proposed that "Quantum Molecular" computer of a neuron consists of the cell cytoskeleton serving as calculating media and input ionic channel sending a hypersound signal to observe these media. The sound spreads through the media travelling along microtubules and microfilaments and switching between those via molecular bridges which serve as elementary switches. The whole system works like a wave guiding net connecting input ionic channels (which generate different sound signals) and output ionic channels (which are controlled by the processed sound signals). Thus the output of such systems depends on the input (controlled by synaptic activity) and on the construction and state of these calculating media. We think that the sound waves spreading through different calculating media solve different physical problems. The construction of the calculating part of the cytoskeleton, according to the hypothesis, is different in different neurons. It is defined by special protein which is produced by DNA, RNA and protein molecular word processor (during brain development and, may be, education). We comment on how the existence of an extremal computer produces an impact on physics and mathematics exemplified by the optimality principle as substitution of physical relativity principle for a complex problem. PMID:1693290

Minina, S V; Liberman, E A

1990-01-01

400

Treefall inputs to boreal soils and implications for C dynamics  

NASA Astrophysics Data System (ADS)

Stand replacing fires are the dominant disturbance of black spruce-dominated boreal forests. A previous study (Manies et al. 2005) determined that fire-killed wood is the source of between 10% and 60% of the carbon (C) found in the deeper, more recalcitrant soil layers of these ecosystems, although these inputs vary spatially and temporally. In that study, we assumed that the turnover time for standing dead to be converted to woody debris was approximately nine years. Over the last decade, however, woody debris inventories within two Alaskan study sites, both of which burned in 1999, indicate a longer turnover time than previously estimated. We have used these new constraints on course woody debris inputs to update the original model and calculated the impact slower fall rates could have on C storage within the deep soil C pool. These new values increase the amount of wood-derived C by up to 20%, which in turn increases deep C storage. Understanding the source of soil C is important for modeling efforts, especially those that need to partition different sources of C to determine rates of C cycling. These results also have implications for land managers who are beginning to consider C storage as a part of their management strategies.

Manies, K.; Harden, J. W.

2011-12-01

401

A closed-form solution to natural image matting.  

PubMed

Interactive digital matting, the process of extracting a foreground object from an image based on limited user input, is an important task in image and video editing. From a computer vision perspective, this task is extremely challenging because it is massively ill-posed -- at each pixel we must estimate the foreground and the background colors, as well as the foreground opacity ("alpha matte") from a single color measurement. Current approaches either restrict the estimation to a small part of the image, estimating foreground and background colors based on nearby pixels where they are known, or perform iterative nonlinear estimation by alternating foreground and background color estimation with alpha estimation. In this paper we present a closed-form solution to natural image matting. We derive a cost function from local smoothness assumptions on foreground and background colors, and show that in the resulting expression it is possible to analytically eliminate the foreground and background colors to obtain a quadratic cost function in alpha. This allows us to find the globally optimal alpha matte by solving a sparse linear system of equations. Furthermore, the closed-form formula allows us to predict the properties of the solution by analyzing the eigenvectors of a sparse matrix, closely related to matrices used in spectral image segmentation algorithms. We show that high quality mattes for natural images may be obtained from a small amount of user input. PMID:18084055

Levin, Anat; Lischinski, Dani; Weiss, Yair

2008-02-01

402

DC servomechanism parameter identification: a Closed Loop Input Error approach.  

PubMed

This paper presents a Closed Loop Input Error (CLIE) approach for on-line parametric estimation of a continuous-time model of a DC servomechanism functioning in closed loop. A standard Proportional Derivative (PD) position controller stabilizes the loop without requiring knowledge on the servomechanism parameters. The analysis of the identification algorithm takes into account the control law employed for closing the loop. The model contains four parameters that depend on the servo inertia, viscous, and Coulomb friction as well as on a constant disturbance. Lyapunov stability theory permits assessing boundedness of the signals associated to the identification algorithm. Experiments on a laboratory prototype allows evaluating the performance of the approach. PMID:21868009

Garrido, Ruben; Miranda, Roger

2012-01-01

403

Development of Purine-Derived 18F-Labeled Pro-drug Tracers for Imaging of MRP1 Activity with PET  

PubMed Central

Multidrug resistance-associated protein 1 (MRP1) is a drug efflux transporter that has been implicated in the pathology of several neurological diseases and is associated with development of multidrug resistance. To enable measurement of MRP1 function in the living brain, a series of 6-halopurines decorated with fluorinated side chains have been synthesized and evaluated as putative pro-drug tracers. The tracers were designed to undergo conjugation with glutathione within the brain and hence form the corresponding MRP1 substrate tracers in situ. 6-Bromo-7-(2-[18F]fluoroethyl)purine showed good brain uptake and rapid metabolic conversion. Dynamic PET imaging demonstrated a marked difference in brain clearance rates between wild-type and mrp1 knockout mice, suggesting that the tracer can allow noninvasive assessment of MRP1 activity in vivo. PMID:24456310

2014-01-01

404

Label-free, live optical imaging of reprogrammed bipolar disorder patient-derived cells reveals a functional correlate of lithium responsiveness.  

PubMed

Development of novel treatments and diagnostic tools for psychiatric illness has been hindered by the absence of cellular models of disease. With the advent of cellular reprogramming, it may be possible to recapitulate the disease biology of psychiatric disorders using patient skin cells transdifferentiated to neurons. However, efficiently identifying and characterizing relevant neuronal phenotypes in the absence of well-defined pathophysiology remains a challenge. In this study, we collected fibroblast samples from patients with bipolar 1 disorder, characterized by their lithium response (n=12), and healthy control subjects (n=6). We identified a cellular phenotype in reprogrammed neurons using a label-free imaging assay based on a nanostructured photonic crystal biosensor and found that an optical measure of cell adhesion was associated with clinical response to lithium treatment. This cellular phenotype may represent a useful biomarker to evaluate drug response and screen for novel therapeutics. PMID:25158003

Wang, J L; Shamah, S M; Sun, A X; Waldman, I D; Haggarty, S J; Perlis, R H

2014-01-01

405

Characterization of the Campbell-Stokes sunshine duration recorder and its ability to derive direct solar radiation by using digital image processing  

NASA Astrophysics Data System (ADS)

The World Meteorological Organization defines the sunshine duration (SD) as the time that, along a given period, direct solar irradiance (DSI) exceeds the threshold level of 120 W/m2. Since the end of 19th century, the Campbell-Stokes sunshine recorder (CSSR) has been the most commonly used instrument used for measuring SD. Due to the large number of long records that exist worldwide, valuable climatic information can be extracted from them. Many authors have used the daily SD (as obtained from the measurement of the length of burn for a given card) to obtain additional information about solar radiation, by using Ångström-Prescott type formulas. Contrarily, the burn width has not been systematically used. Theoretically, the burn is wider (narrower) when the direct insolation is stronger (weaker). The aim of this research is to show the relationship between burn width and DSI, and to prove whether this relationship depends on the type of CSSR and burning card. The research has been carried out in Girona (NE Spain) for a period of two years (from January 2012 to January 2014). Two different models of CSSR (which use different types of cards) and a pyrheliometer from Kipp&Zonen were used to measure SD and DSI, respectively. A semi-automatic method based on image processing of digital scanned images of burnt cards is presented. The method can be summarized in four steps: (i) scan each band on a green background; (ii) apply a digital process to increase the contrast of the burn; (iii) define two/three points in the image, depending of the geometry of the card, to point the center of the day (12.00 TST) on the image and define the trajectory of the sun with 1-minute intervals; and (iv) apply a program to make cross-sections every minute and measure the width of burn. So, after all of this process, we obtain a temporal evolution of the burn width with 1-minute resolution and distinguishing between morning and afternoon. The results show that there is a good correlation between the burn widths obtained from the two types of CSSR. We also observe a quite good correlation with DSI, which is consistent with our hypothesis. However, if we study the threshold value, we obtain a wide range of values that are almost always higher than 120 W/m2, with a significant difference between the morning and afternoon records. Consequently, we consider that the behaviour of cards may also depend on other meteorological variables (temperature, humidity…) affecting the burn. The physical characteristics of the heliograph and of the cardboard from which the bands are made may also have an important role in this relationship. The method was applied to a limited series of cards, but could offer a practical way to exploit the worldwide sets of long-term CSSR data to create long time series of DSI. As there are methods to extract atmospheric aerosol content based on DSI (Linke turbidity factor, Ångström's turbidity coefficient, etc.), SD may become a proxy measurement for turbidity and atmospheric aerosol loading since the late 19th century.

Sanchez-Romero, Alejandro; González, Josep-Abel; Calbó, Josep; Sanchez-Lorenzo, Arturo

2014-05-01

406

Writing to your car: handwritten text input while driving  

Microsoft Academic Search

For in-car navigation, information and entertainment systems, text input is increasingly important. We investigate handwriting as a text input modality and assess where to best position the input surface and how to provide feedback. For this purpose, we created different prototypes that allow text input on the steering wheel and in the central console, as well as visual feedback on

Dagmar Kern; Albrecht Schmidt; Jonas Arnsmann; Thorsten Appelmann; Nillakshi Pararasasegaran; Benjamin Piepiera

2009-01-01

407

INDES User's guide multistep input design with nonlinear rotorcraft modeling  

NASA Technical Reports Server (NTRS)

The INDES computer program, a multistep input design program used as part of a data processing technique for rotorcraft systems identification, is described. Flight test inputs base on INDES improve the accuracy of parameter estimates. The input design algorithm, program input, and program output are presented.

1979-01-01

408

Queue Response to Input Correlation Functions: Discrete Spectral Analysis  

Microsoft Academic Search

A new concept of spectral characterization of the wideband input process in high-speed networks is examined. The eigenstructure technique, through the modeling of input Markov chains, helps localize wideband sources in a subspace, especially in a low frequency band. Simple periodic chains are used for the construction of the input rate process. The input power spectral distribution is defined in

San-qi Li; Chia-lin Hwang

1992-01-01

409

5-Aminolevulinic Acid-derived Tumor Fluorescence: The Diagnostic Accuracy of Visible Fluorescence Qualities as Corroborated by Spectrometry and Histology and Postoperative Imaging  

PubMed Central

BACKGROUND: 5-Aminolevulinic acid is used for fluorescence-guided resections. During resection, different macroscopic fluorescence qualities (“strong,” “weak”) can be distinguished that help guide resections. OBJECTIVE: This prospective study was designed to assess the reliability of visible fluorescence qualities by spectrometry, pathology, and imaging. METHODS: Thirty-three patients with malignant gliomas received 5-aminolevulinic acid (20 mg/kg). After debulking surgery, standardized biopsies were obtained from tissues with “weak” and “strong” fluorescence and from nonfluorescing near and distant brain for blinded assessment of cell density and tissue type (necrosis, solid or infiltrating tumor, normal tissue). The positive predictive value was calculated. Unresected fluorescing tissue was navigated for blinded correlation to postoperative magnetic resonance imaging (MRI). Receiver operating characteristic curves were generated for assessing the classification efficiency of spectrometry. RESULTS: “Strong” fluorescence corresponded to greater spectrometric fluorescence, solidly proliferating tumor, and high cell densities, whereas “weak” fluorescence corresponded to lower spectrometric fluorescence, infiltrating tumor, and medium cell densities. The positive predictive value was 100% in strongly fluorescing tissue and 95% in weakly fluorescing tissue. Spectrometric fluorescence was detected in marginal tissue without macroscopic fluorescence. Depending on the threshold, spectrometry displayed greater sensitivity but lower specificity (accuracy 88.4%). Residual MRI enhancement in the tumor bed was detected in 15 of 23 (65%) patients with residual fluorescence, but in none of the patients without residual fluorescence. CONCLUSION: Macroscopic fluorescence qualities predict solid and infiltrating tumor, providing useful information during resection. Fluorescence appears superior to contrast enhancement on MRI for indicating residual tumor. Spectrometry, on the other hand, is more sensitive but less specific, depending on threshold definition. ABBREVIATIONS: 5-ALA, 5-aminolevulinic acid CI, confidence interval gamma-GT, gamma-glutamyl transpeptidase GBM, glioblastoma multiforme NPV, negative predictive value PPIX, protoporphyrin IX PPV, positive predictive value SD, standard deviation WHO, World Health Organization PMID:24335821

Tonn, Jorg-Christian; Goetz, Claudia; Ullrich, Winfried; Stepp, Herbert; Bink, Andrea; Pietsch, Thorsten; Pichlmeier, Uwe

2013-01-01

410

Prestack time imaging algorithm with simultaneous velocity estimation in hard rock environments  

NASA Astrophysics Data System (ADS)

Reflection seismic imaging faces several difficulties in hard rock environments. One of them is the estimation of the propagation velocity of seismic waves. Therefore, imaging algorithms that do not require prior construction of a velocity model seem promising for such environments. In this paper we illustrate an application of prestack time migration, which does not require an input velocity model, to hard rock conditions, and we demonstrate its effectiveness on synthetic data. This approach is based on an estimation of local event slopes (horizontal slownesses) in common-shot and common-receiver gathers and a subsequent calculation of the migration attributes (migration velocity, vertical traveltime and horizontal coordinates of the migrated reflection point). These attributes allow us to derive all the information needed to construct a time-migrated image. We also use the obta