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1

Image-Derived Input Function from Cardiac Gated Maximum a Posteriori Reconstructed PET Images in Mice  

Microsoft Academic Search

Purpose  The purpose of this study was to determine if accurate image-derived input functions (IDIF) can be measured from cardiac gated\\u000a positron emission tomography (PET) images reconstructed using ordered subset expectation maximization–maximum a posteriori (OSEM-MAP) without further correction.\\u000a \\u000a \\u000a \\u000a \\u000a Procedures  IDIFs from the left ventricle were measured from cardiac gated PET images reconstructed using OSEM-MAP with computed tomography\\u000a (CT)-based attenuation correction for five

Landon W. Locke; Stuart S. Berr; Bijoy K. Kundu

2011-01-01

2

Image-Derived Input Function from Cardiac Gated Maximum a Posteriori Reconstructed PET Images in Mice  

PubMed Central

Purpose To determine if accurate image-derived input functions (IDIF) can be measured from cardiac gated PET images reconstructed using ordered subset expectation maximization – maximum a posteriori (OSEM-MAP) without further correction. Procedures IDIFs from the left ventricle (LV) were measured from cardiac gated PET images reconstructed using OSEM-MAP with CT-based attenuation correction for 5 C57/BL6 mice. The accuracy of the IDIF was tested against blood samples using Bland-Altman analysis. Results Image-derived blood radioactivity concentration values were not significantly different from sampled blood values at two late time points as determined by a paired t-test (P=0.97). Bland-Altman analysis revealed a mean difference of ?0.06 µCi/ml (1%). Using kinetics analysis, the mean myocardial FDG uptake rate constant based on the IDIF was comparable to values reported in the literature based on physical blood sampling. Conclusions Accurate IDIFs can be obtained non-invasively. Although reconstruction times are increased, no further spillover corrections are necessary for IDIFs derived from gated, OSEM-MAP reconstructed images with attenuation correction.

Locke, Landon W.; Berr, Stuart S.; Kundu, Bijoy K.

2010-01-01

3

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.

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

2011-01-01

4

FDG-PET Quantification of Lung Inflammation with Image-Derived Blood Input Function in Mice  

PubMed Central

Dynamic FDG-PET imaging was used to study inflammation in lungs of mice following administration of a virulent strain of Klebsiella (K.) pneumoniae. Net whole-lung FDG influx constant (Ki) was determined in a compartment model using an image-derived blood input function. Methods. K. pneumoniae (~3 x 105 CFU) was intratracheally administered to six mice with 6 other mice serving as controls. Dynamic FDG-PET and X-Ray CT scans were acquired 24 hr after K. pneumoniae administration. The experimental lung time activity curves were fitted to a 3-compartment FDG model to obtain Ki. Following imaging, lungs were excised and immunohistochemistry analysis was done to assess the relative presence of neutrophils and macrophages. Results. Mean Ki for control and K. pneumoniae infected mice were (5.1 ± 1.2) ×10?3 versus (11.4 ± 2.0) ×10?3?min?1, respectively, revealing a 2.24 fold significant increase (P = 0.0003) in the rate of FDG uptake in the infected lung. Immunohistochemistry revealed that cellular lung infiltrate was almost exclusively neutrophils. Parametric Ki maps by Patlak analysis revealed heterogeneous inflammatory foci within infected lungs. Conclusion. The kinetics of FDG uptake in the lungs of mice can be noninvasively quantified by PET with a 3-compartment model approach based on an image-derived input function.

Locke, Landon W.; Williams, Mark B.; Fairchild, Karen D.; Zhong, Min; Kundu, Bijoy K.; Berr, Stuart S.

2011-01-01

5

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

PubMed

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 [(11)C]flumazenil and [(11)C]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; Varnäs, Katarina; Forsberg, Anton; Halldin, Christer; Lansner, Anders; Farde, Lars; Varrone, Andrea

2013-04-10

6

A method of generating image derived input function in quantitative 18F-FDG PET study based on the monotonicity of the input and output function curve  

PubMed Central

Objective A method for defining image-derived input function (IDIF) has been introduced and evaluated for the quantification of the regional cerebral metabolic rate of glucose in positron emission tomography studies. Methods The voxels in the brain vasculature are extracted based on the different monotonicity between the input and output function curves. The TACs of such voxels are averaged to get the uncorrected TAC of the brain vasculature. The IDIF was obtained from the raw TAC after correcting for the partial volume and spillover effects by an empirical formula in conjunction with single blood sample and the TAC of the brain tissue. Data from 16 human subjects were used to test the proposed method. The Patlak approach is used to calculate the net FDG clearance with plasma-derived input function (PDIF) and our generated IDIF, respectively. Results the net FDG clearances calculated with the image-derived input function generated by our approach are not only highly correlated (correlation coefficients close to 1) to, but also highly comparable (regression slopes close to 1, and intercepts close to 0) with those calculated with plasma-derived input function. Conclusion The method used in the present work is feasible and accurate.

Zhou, Shan; Chen, Kewei; Reiman, Eric M; Li, De-min; Shan, Baoci

2013-01-01

7

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

8

Image-derived input function in dynamic human PET\\/CT: methodology and validation with 11 C-acetate and 18 F-fluorothioheptadecanoic acid in muscle and 18 F-fluorodeoxyglucose in brain  

Microsoft Academic Search

Purpose  Despite current advances in PET\\/CT systems, blood sampling still remains the standard method to obtain the radiotracer input\\u000a function for tracer kinetic modelling. The purpose of this study was to validate the use of image-derived input functions\\u000a (IDIF) of the carotid and femoral arteries to measure the arterial input function (AIF) in PET imaging. The data were obtained\\u000a from two

Etienne Croteau; Éric Lavallée; Sébastien M. Labbe; Laurent Hubert; Fabien Pifferi; Jacques A. Rousseau; Stephen C. Cunnane; André C. Carpentier; Roger Lecomte; François Bénard

2010-01-01

9

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

10

Non-invasive estimation of hepatic blood perfusion from H215O-PET images using tissue-derived arterial and portal input functions  

PubMed Central

The liver is perfused through the portal vein and the hepatic artery. When its perfusion is assessed using PET and 15O-labeled water (H215O), calculations require a dual blood input function (DIF), i.e., arterial and portal blood activity curves. The former can be generally obtained invasively, but blood withdrawal from the portal vein is not feasible in humans. The aim of the present study was to develop a new technique to estimate quantitative liver perfusion from H215O-PET images with a completely noninvasive approach. We studied normal pigs (n=14), in which arterial and portal blood tracer concentrations and Doppler ultrasonography flow rates were determined invasively to serve as reference measurements. Our technique consisted of using model DIF to create tissue model function, and the latter to simultaneously fit multiple liver time-activity curves from images. The parameters obtained reproduced the DIF. Simulation studies were performed to examine the magnitude of potential biases in the flow values, and to optimize the extraction of multiple tissue curves from the image. The simulation showed the error associated with assumed parameters was <10%, and the optimal number of tissue curves was between 10 and 20. The estimated DIFs were well reproduced against the measured ones. In addition, the calculated liver perfusion values were not different between the methods and showed a tight correlation (r=0.90). In conclusion, our results demonstrate DIF can be estimated directly from tissue curves obtained through H215O-PET imaging. This suggests the possibility to enable completely noninvasive technique to assess liver perfusion in patho-physiological studies.

Kudomi, Nobuyuki; Slimani, Lotfi; Jarvisalo, Mikko J.; Kiss, Jan; Lautamaki, Riikka; Naum, Gratian A.; Savunen, Timo; Knuuti, Juhani; Iida, Hirokazu; Nuutila, Pirjo; Iozzo, Patricia

2008-01-01

11

Image-derived input function in dynamic human PET/CT: methodology and validation with 11C-acetate and 18F-fluorothioheptadecanoic acid in muscle and 18F-fluorodeoxyglucose in brain  

PubMed Central

Purpose Despite current advances in PET/CT systems, blood sampling still remains the standard method to obtain the radiotracer input function for tracer kinetic modelling. The purpose of this study was to validate the use of image-derived input functions (IDIF) of the carotid and femoral arteries to measure the arterial input function (AIF) in PET imaging. The data were obtained from two different research studies, one using 18F-FDG for brain imaging and the other using 11C-acetate and 18F-fluoro-6-thioheptadecanoic acid (18F-FTHA) in femoral muscles. Methods The method was validated with two phantom systems. First, a static phantom consisting of syringes of different diameters containing radioactivity was used to determine the recovery coefficient (RC) and spill-in factors. Second, a dynamic phantom built to model bolus injection and clearance of tracers was used to establish the correlation between blood sampling, AIF and IDIF. The RC was then applied to the femoral artery data from PET imaging studies with 11C-acetate and 18F-FTHA and to carotid artery data from brain imaging with 18F-FDG. These IDIF data were then compared to actual AIFs from patients. Results With 11C-acetate, the perfusion index in the femoral muscle was 0.34±0.18 min?1 when estimated from the actual time–activity blood curve, 0.29±0.15 min?1 when estimated from the corrected IDIF, and 0.66±0.41 min?1 when the IDIF data were not corrected for RC. A one-way repeated measures (ANOVA) and Tukey’s test showed a statistically significant difference for the IDIF not corrected for RC (p<0.0001). With 18F-FTHA there was a strong correlation between Patlak slopes, the plasma to tissue transfer rate calculated using the true plasma radioactivity content and the corrected IDIF for the femoral muscles (vastus lateralis r=0.86, p=0.027; biceps femoris r=0.90, p=0.017). On the other hand, there was no correlation between the values derived using the AIF and those derived using the uncorrected IDIF. Finally, in the brain imaging study with 18F-FDG, the cerebral metabolic rate of glucose (CMRglc) measured using the uncorrected IDIF was consistently overestimated. The CMRglc obtained using blood sampling was 13.1±3.9 mg/100 g per minute and 14.0±5.7 mg/100 g per minute using the corrected IDIF (r2=0.90). Conclusion Correctly obtained, carotid and femoral artery IDIFs can be used as a substitute for AIFs to perform tracer kinetic modelling in skeletal femoral muscles and brain analyses.

Croteau, Etienne; Lavallee, Eric; Labbe, Sebastien M.; Hubert, Laurent; Pifferi, Fabien; Rousseau, Jacques A.; Cunnane, Stephen C.; Carpentier, Andre C.; Lecomte, Roger

2010-01-01

12

Single-Input–Dual-Output Modeling of Image-Based Input Function Estimation  

Microsoft Academic Search

Purpose  Quantification of small-animal positron emission tomography (PET) images necessitates knowledge of the plasma input function\\u000a (PIF). We propose and validate a simplified hybrid single-input–dual-output (HSIDO) algorithm to estimate the PIF.\\u000a \\u000a \\u000a \\u000a \\u000a Procedures  The HSIDO algorithm integrates the peak of the input function from two region-of-interest time–activity curves with a tail\\u000a segment expressed by a sum of two exponentials. Partial volume parameters are

Yi Su; Kooresh I. Shoghi

2010-01-01

13

Standards for image input devices: review and forecast  

NASA Astrophysics Data System (ADS)

Driven by the rapid growth of computer multimedia and digital broadcast television production and facilitated by the ever-increasing speed of digital video processing circuits, the development and issuance of standards addressing the transfer of images continues to accelerate. While this proliferation appears to widen the options available to the systems designer, it also tends to obscure the basic similarities among the various standards without revealing their key differences. Understanding the implications of these differences, especially as they involve critical timing and channel configuration issues, is important to the user who must assure successful video data transfer. Unfortunately, and despite the many projects underway, the available standards defining the interfaces to image input devices remain inadequate to fully support the designer tasked with producing and maintaining high quality video data acquisition. In this review, we consider each of the key interfaces in turn, describe and compare the standardized choices available, point up shortcomings in the application of these choices, describe ongoing work intended to address these shortcomings, and suggest additional standards development which might benefit the user of image input devices. We also hope to help the user to ask the right questions and develop the right answers.

Gilblom, David L.

1996-01-01

14

Unsupervised Learning of Overlapping Image Components Using Divisive Input Modulation  

PubMed Central

This paper demonstrates that nonnegative matrix factorisation is mathematically related to a class of neural networks that employ negative feedback as a mechanism of competition. This observation inspires a novel learning algorithm which we call Divisive Input Modulation (DIM). The proposed algorithm provides a mathematically simple and computationally efficient method for the unsupervised learning of image components, even in conditions where these elementary features overlap considerably. To test the proposed algorithm, a novel artificial task is introduced which is similar to the frequently-used bars problem but employs squares rather than bars to increase the degree of overlap between components. Using this task, we investigate how the proposed method performs on the parsing of artificial images composed of overlapping features, given the correct representation of the individual components; and secondly, we investigate how well it can learn the elementary components from artificial training images. We compare the performance of the proposed algorithm with its predecessors including variations on these algorithms that have produced state-of-the-art performance on the bars problem. The proposed algorithm is more successful than its predecessors in dealing with overlap and occlusion in the artificial task that has been used to assess performance.

Spratling, M. W.; De Meyer, K.; Kompass, R.

2009-01-01

15

Monte Carlo simulations of clinical PET and SPECT scans: impact of the input data on the simulated images  

NASA Astrophysics Data System (ADS)

Monte Carlo simulations of emission tomography have proven useful to assist detector design and optimize acquisition and processing protocols. The more realistic the simulations, the more straightforward the extrapolation of conclusions to clinical situations. In emission tomography, accurate numerical models of tomographs have been described and well validated under specific operating conditions (collimator, radionuclide, acquisition parameters, count rates, etc). When using these models under these operating conditions, the realism of simulations mostly depends on the activity distribution used as an input for the simulations. It has been proposed to derive the input activity distribution directly from reconstructed clinical images, so as to properly model the heterogeneity of the activity distribution between and within organs. However, reconstructed patient images include noise and have limited spatial resolution. In this study, we analyse the properties of the simulated images as a function of the properties of the reconstructed images used to define the input activity distributions in 18F-FDG PET and 131I SPECT simulations. The propagation through the simulation/reconstruction process of the noise and spatial resolution in the input activity distribution was studied using simulations. We found that the noise properties of the images reconstructed from the simulated data were almost independent of the noise in the input activity distribution. The spatial resolution in the images reconstructed from the simulations was slightly poorer than that in the input activity distribution. However, using high-noise but high-resolution patient images as an input activity distribution yielded reconstructed images that could not be distinguished from clinical images. These findings were confirmed by simulated highly realistic 131I SPECT and 18F-FDG PET images from patient data. In conclusion, we demonstrated that 131I SPECT and 18F-FDG PET images indistinguishable from real scans can be simulated using activity maps with spatial resolution higher than that used in routine clinical applications.

Stute, S.; Carlier, T.; Cristina, K.; Noblet, C.; Martineau, A.; Hutton, B.; Barnden, L.; Buvat, I.

2011-10-01

16

Closed-Loop Input Impedance of PWM Buck-Derived DC-DC Converters  

Microsoft Academic Search

The small-signal closed-loop input impedance is derived for the PWM buck DC-DC converter operated in continuous conduction mode (CCM), taking into account all parasitic resistances. The plots of the closed-loop input impedance are shown versus frequency for four values of the equivalent series resistance of the capacitor

Marian K. Kazimierczuk; Robert Cravens II; Alberto Reatti

1994-01-01

17

Fractional Fourier transform based image multiplexing and encryption technique for four-color images using input images as keys  

NASA Astrophysics Data System (ADS)

A digital technique for multiplexing and encryption of four RGB images has been proposed using the fractional Fourier transform (FRT). The four input RGB images are first converted into their indexed image formats and subsequently multiplexed into a single image through elementary mathematical steps prior to the encryption. The encryption algorithm uses two random phase masks in the input- and the FRT domain, respectively. These random phase masks are especially designed using the input images. As the encryption is carried out through a single channel, the technique is more compact and faster as compared to the multichannel techniques. Different fractional orders, the random masks in input-, and FRT domain are the keys for decryption as well as de-multiplexing. The algorithms to implement the proposed multiplexing-, and encryption scheme are discussed, and results of digital simulation are presented. Simulation results show that the technique is free from cross-talk. The performance of the proposed technique has also been analyzed against occlusion, noise, and attacks using partial windows of the correct random phase keys. The robustness of the technique against known-, and chosen plain-text attacks has also been explained.

Joshi, Madhusudan; Shakher, Chandra; Singh, Kehar

2010-06-01

18

MRI-derived arterial input functions for PET kinetic modelling in rats  

NASA Astrophysics Data System (ADS)

Simultaneous PET–MR acquisition provides the high temporal and spatial resolution of MRI with the specificity of PET. In PET, accurate modelling of physiological function in vivo requires the time-activity curve of tracer in blood plasma, known as the arterial input function (AIF). As the gold standard method of blood sampling is inherently prohibitive in the small animal case, here we discuss how we prepare to rapidly sample MRI signals from gadolinium-doped tracer to obtain the tracer input functions from a simultaneous PET-MR measurement. ?R2* measurements taken from EPI images were used to obtain first pass bolus AIFs in the rat brain from DSC-MRI datasets of 5 rats. AIFs obtained using our automatic algorithm were found to be consistent between animals and compared well with manual methods without need for a priori voxel selection. A variable flip angle FLASH sequence used for T1 mapping was successfully tested in a phantom study, providing accurate measurements of Gd concentration.

Evans, Eleanor; Sawiak, Stephen J.; Adrian Carpenter, T.

2013-02-01

19

Use of multimedia input in automated image annotation and content-based retrieval  

NASA Astrophysics Data System (ADS)

This research explores the interaction of linguistic and photographic information in an integrated text/image database. By utilizing linguistic descriptions of a picture (speech and text input) coordinated with pointing references to the picture, we extract information useful in two aspects: image interpretation and image retrieval. In the image interpretation phase, objects and regions mentioned in the text are identified; the annotated image is stored in a database for future use. We incorporate techniques from our previous research on photo understanding using accompanying text: a system, PICTION, which identifies human faces in a newspaper photograph based on the caption. In the image retrieval phase, images matching natural language queries are presented to a user in a ranked order. This phase combines the output of (1) the image interpretation/annotation phase, (2) statistical text retrieval methods, and (3) image retrieval methods (e.g., color indexing). The system allows both point and click querying on a given image as well as intelligent querying across the entire text/image database.

Srihari, Rohini K.

1995-03-01

20

Image Deblurring Using Derivative Compressed Sensing for Optical Imaging Application  

Microsoft Academic Search

Reconstruction of multidimensional signals from the samples of their partial derivatives is known to be a standard problem in inverse theory. Such and similar problems routinely arise in numerous areas of applied sciences, including optical imaging, laser interferometry, computer vision, remote sensing and control. Though being ill-posed in nature, the above problem can be solved in a unique and stable

Mohammad Rostami; Oleg Michailovich; Zhou Wang

2011-01-01

21

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

22

Forecasting future phosphorus export to the Laurentian Great Lakes from land-derived nutrient inputs  

NASA Astrophysics Data System (ADS)

Anthropogenic use of the land through agricultural and urban activities has significantly increased phosphorus loading to rivers that flow to the Great Lakes. Phosphorus (P) is a critical element in the eutrophication of the freshwater ecosystems, most notably the Great Lakes. To better understand factors influencing phosphorus delivery to aquatic systems and thus their potential harmful effects to lake ecosystems, models that predict P export should incorporate account for changing changes in anthropogenic activities. Land-derived P from high yielding sources, such as agriculture and urban areas, affect eutrophication at various scales (e.g. specific bays to all of Lake Erie). SPARROW (SPAtially Referenced Regression On Watershed attributes) is a spatially explicit watershed model that has been used to understand linkages between land-derived sources and nutrient transport to the Great Lakes. The Great Lakes region is expected to experience a doubling of urbanized areas along with a ten percent increase in agricultural use over the next 40 years, which is likely to increase P loading. To determine how these changes will impact P loading, SPARROW have been developed that relate changes in land use to changes in nutrient sources, including relationships between row crop acreage and fertilizer intensity and urban land use and point source intensity. We used land use projections from the Land Transformation Model, a, spatially explicit, neural-net based land change model. Land use patterns from current to 2040 were used as input into HydroSPARROW, a forecasting tool that enables SPARROW to simulate the effects of various land-use and climate scenarios. Consequently, this work is focusing on understanding the effects of how specific agriculture and urbanization activities affect P loading in the watersheds of the Laurentian Great Lakes to potentially find strategies to reduce the extent and severity of future eutrophication.

LaBeau, M. B.; Robertson, D. M.; Mayer, A. S.; Pijanowski, B. C.

2011-12-01

23

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

24

Derivation of Auroral Conductances from IMAGE FUV  

NASA Astrophysics Data System (ADS)

Auroral emissions are observed in 3 separate Far-Ultraviolet (FUV) wavelength regimes by IMAGE. The Wideband Imaging Camera (WIC) is sensitive mainly to N2 LBH and N I emissions in the 140-190-nm range, while the Spectrographic Imager (SI) spectrally separates the OI 135.6-nm emission and Doppler shifted hydrogen emissions of the proton aurora at 121.8 nm. The brightness of the N2 LBH and OI 135.6-nm emissions depend in part on the spectrum and total energy flux of incoming electrons, and on the height-density profile of the respective species, and O2. Due mainly to these atmospheric factors, the ratio of the N2 and OI emissions depends strongly on the characteristic energy of precipitating electrons which, once estimated, can in turn be used to calculate the total energy flux. The proton aurora generates secondary electrons, which excite additional emissions of N2 and OI. It is not possible to absolutely determine either the total proton energy flux or the characteristic proton energy () with a single proton imaging channel. However, the proton-induced N2 and OI emissions depend mainly on the total proton energy flux, so reasonable estimates of can be used in the calculation of proton energy input. Ground-based or in-situ observations of proton energies can help in this determination. With accurate corrections for N2 and OI airglow emissions, and formulae such as those provided by Robinson et al. [1987], IMAGE FUV can provide global maps of height-integrated conductivity (conductance) in the auroral oval. It is also possible to examine the degree to which the proton aurora contributes to enhanced conductance on a global scale. The promise of providing these conductances using IMAGE's real-time capabilities will be discussed. Robinson, R. M., R. R. Vondrak, K. Miller, T. Dabbs, and D. Hardy, On Calculating Ionospheric Conductances from the Flux and Energy of Precipitating Electrons, J. Geophys. Res., 92, 2566, 1987.

Immel, T. J.; Mende, S. B.; Frey, H. U.; Gerard, J.; Hubert, B.

2001-05-01

25

Delay-dependent H? control of linear systems with input delay using composite state-derivative feedback  

Microsoft Academic Search

H? control problem for input-delayed systems is considered in this paper. A composite state-derivative control law is used, in which, a composition of the state variables and their derivatives appear in the control law. Thus, the resulting closed-loop system turns into a specific time-delay system of neutral type. The significant specification of this neutral system is that its delayed term

A. Shariati; H. D. Taghirad; B. Labibi

2010-01-01

26

Manufacturing Technology for Production of 80-mm-Input, 40-mm-Output (80/40) Image Intensifier Tubes.  

National Technical Information Service (NTIS)

Manufacturing techniques were established for fabricating image intensifier tubes with 80-mm input and 40-mm output, suitable for interface with the 40-mm SEC camera tube. The manufacturing processes, techniques and controls necessary to fabricate a limit...

1970-01-01

27

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

PubMed Central

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

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

2010-01-01

28

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

29

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

30

Input-Specific Spine Entry of Soma-Derived Vesl-1S Protein Conforms to Synaptic Tagging  

Microsoft Academic Search

Late-phase synaptic plasticity depends on the synthesis of new proteins that must function only in the activated synapses. The synaptic tag hypothesis requires input-specific functioning of these proteins after undirected transport. Confirmation of this hypothesis requires specification of a biochemical tagging activity and an example protein that behaves as the hypothesis predicts. We found that in rat neurons, soma-derived Vesl-1S

Daisuke Okada; Fumiko Ozawa; Kaoru Inokuchi

2009-01-01

31

Derivative encoding for parallel magnetic resonance imaging a  

PubMed Central

Purpose: To introduce a linear shift-invariant relationship between the partial derivatives of k space signals acquired using multichannel receive coils and to demonstrate that k space derivatives can be used for image unwrapping.Methods: Fourier transform of k space derivatives contains information on the spatial origins of aliased pixels; therefore, images can be reconstructed by k space derivatives. Fully sampled phantom and brain images acquired at 3 T using a standard eight channel receive coil were used to validate the k space derivatives theorem by unwrapping aliased images.Results: Derivative encoding leads to new methods for parallel imaging reconstruction in both k space and image domains. Noise amplification in sensitivity encoding image reconstruction, which is considered to produce the optimal SNR, can be further reduced using k space derivative encoding without making any assumptions on the characteristics of the images to be reconstructed.Conclusions: This work demonstrated that the partial derivative of the k space signal acquired from one coil with respect to one direction can be expressed as a sum of partial derivatives of signals from multiple coils with respect to the perpendicular k space direction(s). This relationship between the partial derivatives of k space signals is linear and shift-invariant in the Cartesian coordinate system.

Shen, Jun

2011-01-01

32

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

Microsoft Academic Search

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

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

2009-01-01

33

Sensory inputs from whisking movements modify cortical whisker maps visualized with functional magnetic resonance imaging  

PubMed Central

Rodents vary the frequency of whisking movements during exploratory and discriminatory behaviours. The effect of whisking frequency on whisker cortical maps was investigated by simulating whisking at physiological frequencies and imaging the whisker representations with blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI). Repetitive deflection of many right-sided whiskers at 10 Hz evoked a positive BOLD response that extended across contralateral primary somatosensory cortex (SI) and secondary somatosensory cortex (SII). In contrast, synchronous deflection of two adjacent whiskers (right C1 and C2) at 10 Hz evoked separate positive BOLD responses in contralateral SI and SII that were predominantly located in upper cortical layers. The positive BOLD responses were separated and partially surrounded by a negative BOLD response that was mainly in lower cortical layers. Two-whisker representations varied with the frequency of simulated whisking. Positive BOLD responses were largest with 7 Hz deflection. Negative BOLD responses were robust at 10 Hz, but were weaker or absent with 7 Hz or 3 Hz deflection. Our findings suggest that sensory inputs attributable to the frequency of whisking movements modify whisker cortical representations.

de Celis Alonso, Benito; Lowe, Andrew S.; Dear, John P.; Lee, Kalok C.; Williams, Steven C. R.; Finnerty, Gerald T.

2007-01-01

34

A text input system developed by using lips image recognition based LabVIEW for the seriously disabled.  

PubMed

In this paper, we present a text input system for the seriously disabled by using lips image recognition based on LabVIEW. This system can be divided into the software subsystem and the hardware subsystem. In the software subsystem, we adopted the technique of image processing to recognize the status of mouth-opened or mouth-closed depending the relative distance between the upper lip and the lower lip. In the hardware subsystem, parallel port built in PC is used to transmit the recognized result of mouth status to the Morse-code text input system. Integrating the software subsystem with the hardware subsystem, we implement a text input system by using lips image recognition programmed in LabVIEW language. We hope the system can help the seriously disabled to communicate with normal people more easily. PMID:17271421

Chen, S C; Shao, C L; Liang, C K; Lin, S W; Huang, T H; Hsieh, M C; Yang, C H; Luo, C H; Wuo, C M

2004-01-01

35

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

Microsoft Academic Search

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

Imke Radtke; Uwe Haberlandt

2010-01-01

36

Input of deeply derived carbon dioxide in southern Apennine regional aquifers (Italy)  

Microsoft Academic Search

Twenty regional carbonate aquifers of the southern Apennine have been studied to evaluate the occurrence of the influx of deeply derived CO2 in to groundwaters of that region. Eighty-three springs, representative from 60 % to 97 % of the total water discharge of the aquifers (˜ 97 m3 s-1), were sampled in order to obtain a representative data set of

C. Cardellini; G. Chiodini; F. Frondini; S. Giaquinto; S. Caliro; F. Parello

2003-01-01

37

Determination of electron and proton auroral energy inputs from FUV-IMAGE  

NASA Astrophysics Data System (ADS)

The FUV experiment onboard the IMAGE spacecraft offers the unique possibility to obtain simultaneous snapshots of the global north aurora every 2 minutes in three different spectral channels. The WIC camera has a broadband channel covering the 135-190 nm interval including the N2 LBH bands, part of which may be absorbed by O2. The SI13 channel is centered on the OI 135.6 nm line which is optically thin and includes a ~ 40% LBH contribution. Finally, the SI12 camera images the Doppler-shifted Ly-? emission excited by the proton aurora. This set of instrumentation is combined with auroral models to determine the electron and the proton energy fluxes from the magnetosphere. Examples will be presented and compared with the values deduced from the NOAA satellites. Simultaneous in-situ measurements of the particle characteristic energy have been combined with the data extracted from the FUV images to validate the models and derive empirical relationships between the particle flux measured by the detectors and the brightness observed by FUV-IMAGE at the footprint of the same magnetic field line. Finally, we will assess the ability to deduce the characteristic energy of the auroral particles from the ratio of co-registered images in the WIC and SI13 cameras. This method is based on the difference of vertical distribution of the LBH and the OI 135.6 nm emissions. It offers the potential to globally remotely sense not only the energy flux from the magnetosphere but also the main features of the electron characteristic energy.

Gérard, J.; Hubert, B.; Meurant, M.; Frey, H. U.; Mende, S. B.; Immel, T.; Bisikalo, D. V.; Shematovich, V. I.; Gladstone, G. R.

2001-05-01

38

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

PubMed

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

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

2011-01-13

39

Objective image quality measure derived from digital image power spectra  

NASA Astrophysics Data System (ADS)

An objective image quality measure based on the digital image power spectrum of normally acquired arbitrary scenes is developed. This image quality measure, which does not require imaging either designed targets or a constant scene, utilizes the previously known invariance property for the power spectra of arbitrary scenes. The measure incorporates a representation of the human visual system, a novel approach to account for directional differences in perspective (scale) for obliquely acquired scenes, and a filter developed to account for imaging system noise as specifically evidenced in the image power spectra. The primary application is to assess the quality of digital images relevant to the image task of detection, recognition, and identification of man-made objects from softcopy displayed versions of visible spectral region digital aerial images. Experimental verification is presented demonstrating very good correlation (r = 0.9) of this objective quality measure with visual quality assessments.

Nill, Norman B.; Bouzas, Brian H.

1992-04-01

40

Diphenyl Ether Derivatives and Their Use for Imaging Serotonin Transporters.  

National Technical Information Service (NTIS)

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

H. F. Kung

2005-01-01

41

The Chemokine Stromal Cell-Derived Factor-1 Regulates GABAergic Inputs to Neural Progenitors in the Postnatal Dentate Gyrus  

PubMed Central

Stromal cell-derived factor-1 (SDF-1) and its receptor CXC chemokine receptor 4 (CXCR4) are important regulators of the development of the dentate gyrus (DG). Both SDF-1 and CXCR4 are also highly expressed in the adult DG. We observed that CXCR4 receptors were expressed by dividing neural progenitor cells located in the subgranular zone (SGZ) as well as their derivatives including doublecortin-expressing neuroblasts and immature granule cells. SDF-1 was located in DG neurons and in endothelial cells associated with DG blood vessels. SDF-1-expressing neurons included parvalbumin-containing GABAergic interneurons known as basket cells. Using transgenic mice expressing an SDF-1-mRFP1 (monomeric red fluorescence protein 1) fusion protein we observed that SDF-1 was localized in synaptic vesicles in the terminals of basket cells together with GABA-containing vesicles. These terminals were often observed to be in close proximity to dividing nestin-expressing neural progenitors in the SGZ. Electrophysiological recordings from slices of the DG demonstrated that neural progenitors received both tonic and phasic GABAergic inputs and that SDF-1 enhanced GABAergic transmission, probably by a postsynaptic mechanism. We also demonstrated that, like GABA, SDF-1 was tonically released in the DG and that GABAergic transmission was partially dependent on coreleased SDF-1. These data demonstrate that SDF-1 plays a novel role as a neurotransmitter in the DG and regulates the strength of GABAergic inputs to the pool of dividing neural progenitors. Hence, SDF-1/CXCR4 signaling is likely to be an important regulator of adult neurogenesis in the DG.

Bhattacharyya, Bula J.; Banisadr, Ghazal; Jung, Hosung; Ren, Dongjun; Cronshaw, Darran G.; Zou, Yongrui; Miller, Richard J.

2009-01-01

42

Methods for edge enhancement in color images based on derivative operations  

NASA Astrophysics Data System (ADS)

We present optical methods for edge enhancement in color images using optical derivative operations (first order derivative and Laplacian operator). The proposed methods is based on the polarization properties of liquid-crystal displays (LCD) and on the capacity of digital micro mirror devices to generate a (positive) copy of the digital image used as input, and simultaneously a complementary color replica of it. In the proposed optical setup the negative and positive replicas are at the same time imagined across a plane. First we analyzed the case when the negative replica has a lateral differential displacement relative to the original one; an image with enhanced first derivatives along a specific direction is obtained. In the case when the negative replica is low-pass filtered, one obtains the Laplacian of the original image. Unlike Fourier, our proposal works with incoherent illumination and does not require precise alignment, and thus, it could be a useful tool for edge extraction/enhancement in large images in real-time applications. Validation experiments are presented.

Flores, Jorge L.; Ferrari, José A.; Fernández, Ariel; Alonso, Julia R.; Ayubi, Gastón A.; Di Martino, J. Matías

2012-10-01

43

Data-derived spatiotemporal resolution constraints for global auroral imagers  

NASA Astrophysics Data System (ADS)

We present new data-derived constraints on spatiotemporal resolution of global auroral imagers. The reported results are based on an extensive set of images from two previously flown instruments, POLAR UVI and IMAGE WIC, processed using the event detection methodology developed by Uritsky et al. (2002, 2003, 2006). We use the cross-scale analysis of ground-based and spacecraft observations of auroral emission regions by Kozelov et al. (2004) to derive the power law exponent relating spatial and temporal scales of auroral precipitation events, and estimate the normalization factor entering this relation using the satellite data. Our results show the existence of a nontrivial scaling relation between the relaxation time and the spatial dimension of auroral emission events. We use this relation as a proxi to the resolution scaling function providing non-redundant combinations of spatial and temporal resolution of an optimized auroral imager consistent with the dynamics of multiscale auroral precipitation.

Uritsky, Vadim M.; Donovan, Eric; Trondsen, Trond; Pineau, Deanna; Kozelov, Boris V.

2010-09-01

44

Early Time Points Perfusion Imaging: Theoretical Analysis of Correction Factors for relative cerebral blood flow Estimation Given Local Arterial Input Function  

PubMed Central

If local arterial input function (AIF) could be identified, we present a theoretical approach to generate a correction factor based on local AIF for the estimation of relative cerebral blood flow (rCBF) under the framework of early time points perfusion imaging (ET). If C(t), the contrast agent bolus concentration signal time course, is used for rCBF estimation in ET, the correction factor for C(t) is the integral of its local AIF. The recipe to apply the correction factor is to divide C(t) by the integral of its local AIF to obtain the correct rCBF. By similar analysis, the correction factor for the maximum derivative (MD1) of C(t) is the maximum signal of AIF and the correction factor for the maximum second derivative (MD2) of C(t) is the maximum derivative of AIF. In the specific case of using normalized gamma-variate function as a model for AIF, the correction factor for C(t) (but not for MD1) at the time to reach the maximum derivative is relatively insensitive to the shape of the local AIF.

Kwong, Kenneth K.; Chesler, David A.

2011-01-01

45

Delay-Dependent Stabilization of Linear Input-Delayed Systems with Composite State-Derivative Feedback: Constant and Time-Varying Delays  

Microsoft Academic Search

This paper considers stability problem for input- delayed systems for both constant and time-varying delay case. A new composite state-derivative control law is introduced, in which, a composition of the state variables and their derivatives appear in control law. By this means, the resulting closed-loop system becomes a particular time-delay system of neutral type. The significant specification of this neutral

A. Shariati; H. D Taghirad; B. Labibi

46

Dynamic contrast-enhanced MRI in mice at high field: Estimation of the arterial input function can be achieved by phase imaging.  

PubMed

PURPOSE: Quantitative dynamic contrast-enhanced MRI requires an accurate arterial input function (AIF). At high field, increased susceptibility effects and decreased longitudinal relaxivity of contrast agents lead to predominant T(2) * effects in blood vessels, producing a dip in signal during passage of the contrast agent bolus. This study determined phase-derived AIFs in mice at 11.7 T. METHODS: AIFs were measured in aorta/vena cava for five FBV/N mice and in iliac arteries/veins for five NMRI mice with a fast low angle shot sequence, simultaneously with tumor imaging (temporal resolution: 1.19 s). Gadoterate was injected into the tail vein as a bolus (0.286 mmol Gd/kg). An in vitro study was also performed to calculate the relationship between ?? and gadolinium concentration. RESULTS: The phantom system confirmed the linear relationship between measured ?? and gadolinium concentration. In vivo, a dip in arterial magnitude signal made it impossible to quantify the AIF. With phase imaging, a clear quantifiable bolus peak was obtained; peak measured concentration in plasma was 4.9?±?0.9 mM for FBV/N mice and 8.0?±?0.6 mM for NMRI mice, close to the expected concentration of 6.8 mM. CONCLUSION: Phase imaging seems to be an appropriate means to measure the AIF of mice at high field. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc. PMID:23440927

Fruytier, A-C; Magat, J; Colliez, F; Jordan, B; Cron, G; Gallez, B

2013-02-25

47

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

Microsoft Academic Search

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

X. Zhuge

2010-01-01

48

Learning photographic global tonal adjustment with a database of input\\/output image pairs  

Microsoft Academic Search

Adjusting photographs to obtain compelling renditions requires skill and time. Even contrast and brightness adjustments are challenging because they require taking into account the image content. Photographers are also known for having different retouching preferences. As the result of this complexity, rule-based, one-size-fits-all automatic techniques often fail. This problem can greatly benefit from supervised machine learning but the lack of

Vladimir Bychkovsky; Sylvain Paris; Eric Chan; Fredo Durand

2011-01-01

49

Learning photographic global tonal adjustment with a database of input \\/ output image pairs  

Microsoft Academic Search

Adjusting photographs to obtain compelling renditions requires skill and time. Even contrast and brightness adjustments are challenging because they require taking into account the image content. Photographers are also known for having different retouching preferences. As the result of this complexity, rule-based, one-size-fits-all automatic techniques often fail. This problem can greatly benefit from supervised machine learning but the lack of

Vladimir Bychkovsky; Sylvain Paris; Eric Chan; Fredo Durand

2011-01-01

50

Resistive grid image filtering: input\\/output analysis via the CNN framework  

Microsoft Academic Search

The cellular neural network framework developed by L.O. Chua and L. Yang (IEEE Trans. Circuits Syst., vol.32, Oct. 1988) is used to analyze the image filtering operation performed by the VLSI linear resistive grid. In particular, it is shown in detail how the resistive grid can be cast as a CNN, and the use of frequency-domain techniques to characterize the

Bertram E. Shi; L. O. Chua

1992-01-01

51

Effects of reconstruction filter and input parameter variability on object detectability in CT imaging  

NASA Astrophysics Data System (ADS)

The purpose of this work is to investigate and quantify the effects of technical parameter variability and reconstruction algorithm on image quality and object detectability. To accomplish this, metrics of both noise and signal to noise ratio (SNR) are explored and then applied in object detection tasks using a computer aided diagnosis (CAD) system. The noise power spectrum (NPS) is investigated as a noise metric in that it describes both the magnitude of noise and the spatial characteristics of noise that are introduced by the reconstruction algorithm. The NPS was found to be much more robust than the conventional standard deviation metric. The noise equivalent quanta (NEQ) is also studied as a tool for comparing effects of acquisition parameters (esp. mAs) on noise and, as NEQ is not influenced by reconstruction filter or other post-processing, its utility for comparison across different techniques and manufacturers is demonstrated. The Ideal Bayesian Observer (IBO) and Non-Prewhitening Matched Filter (NPWMF) are investigated as SNR metrics under a variety of acquisition and reconstruction conditions. The signal and noise processes of image formation were studied individually, which allowed for analysis of their separate effects on the overall SNR. The SNR metrics were found to characterize the influence of reconstruction filter and technical parameter variability with high sensitivity. To correlate the above SNR metrics with detection, signal images were combined with noise images and passed to a CAD system. A simulated lung nodule detection task was performed on a series of objects of increasing contrast. The average minimum contrast detected and corresponding IBO and NPWMF SNR values were recorded over 100 trials for each reconstruction filter and technical parameter condition studied. Among the trends discovered, it was found that detectability scales with SNR as mAs is varied. Furthermore, the CAD system appears to under-perform when sharp algorithms are used. Conclusion. Robust noise metrics and SNR metrics were explored and applied under a variety of detections tasks. The results offer insight into both potential improvements for CAD, as well as for improving protocol design.

Boedeker, Kirsten L.

52

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

PubMed Central

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

Henderson, Luke A.; Macefield, Vaughan G.

2013-01-01

53

Detection of blood-related signal from a series of fingerprint images acquired during an input action  

NASA Astrophysics Data System (ADS)

When a finger is pressed against a flat plate and deformed, blood inside the finger moves away from the deformed area. This causes the finger to change its appearance from reddish to white. As the finger leaves the plate, the blood comes back and it looks reddish again. We have proposed to use this color change to distinguish genuine fingers from artificial ones for un-attended fingerprint identification systems. This blood-related signal may reflect the stiffness of the peripheral blood vessels and therefore it may be correlated with some health conditions such as blood pressure. In experiments, we used a fingerprint sensor based on scattered light detection. Because the spectra of the light scattered by the deformed fingers showed large changes mostly in the green portion, an LED emitting at 525 nm at peak strength was used. First, we compared series of fingerprint images acquired during a normal input action and those obtained while a rubber band occluded the blood flow. The occluded finger required a larger force to exhibit a similar change for these pixel values than the finger without the rubber band. Second, we analyzed fingerprint images recorded by six volunteers. We defined some indices based on the pixel values of the fingerprint images and the pressure applied to the fingers. The correlation coefficient of one of such indices and the average blood pressure of the participants was 0.86. Although the number of the subjects is small, this initial result is encouraging.

Fujieda, Ichiro; Hori, Atsushi; Kurita, Masashi

2007-10-01

54

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

2013-03-13

55

Strategies for the generation of parametric images of [11C]PIB with plasma input functions considering discriminations and reproducibility.  

PubMed

Pittsburgh compound B or [11C]PIB is an amyloid imaging agent which shows a clear differentiation between subjects with Alzheimer's disease (AD) and controls. However the observed signal difference in other forms of dementia such as dementia with Lewy bodies (DLB) is smaller, and mild cognitively impaired (MCI) subjects and some healthy elderly normals may show intermediate levels of [11C]PIB binding. The cerebellum, a commonly used reference region for non-specific tracer uptake in [11C]PIB studies in AD may not be valid in Prion disorders or monogenic forms of AD. The aim of this work was to: 1-compare methods for generating parametric maps of [11C]PIB retention in tissue using a plasma input function in respect of their ability to discriminate between AD subjects and controls and 2-estimate the test-retest reproducibility in AD subjects. 12 AD subjects (5 of which underwent a repeat scan within 6 weeks) and 10 control subjects had 90 minute [11C]PIB dynamic PET scans, and arterial plasma input functions were measured. Parametric maps were generated with graphical analysis of reversible binding (Logan plot), irreversible binding (Patlak plot), and spectral analysis. Between group differentiation was calculated using Student's t-test and comparisons between different methods were made using p values. Reproducibility was assessed by intraclass correlation coefficients (ICC). We found that the 75 min value of the impulse response function showed the best group differentiation and had a higher ICC than volume of distribution maps generated from Logan and spectral analysis. Patlak analysis of [11C]PIB binding was the least reproducible. PMID:19591948

Edison, Paul; Brooks, David J; Turkheimer, Federico E; Archer, Hilary A; Hinz, Rainer

2009-07-08

56

Solar EUV and XUV energy input to thermosphere on solar rotation time scales derived from photoelectron observations.  

NASA Astrophysics Data System (ADS)

Solar radiation below ~100 nm produces photoelectrons, a substantial portion of the F region ionization, most of the E region ionization, and drives chemical reactions in the thermosphere. Unquantified uncertainties in thermospheric models exist because of uncertainties in solar irradiance models used to fill spectral and temporal gaps in solar irradiance observations. We investigate uncertainties in solar energy input to the thermosphere on solar rotation time scales using photoelectron observations from the FAST satellite. We compare observed and modeled photoelectron energy spectra using two photoelectron production codes driven by five different solar irradiance models. We observe about 1.7 per cent of the ionizing solar irradiance power in the escaping photoelectron flux. Most of the code/model pairs used reproduce the average escaping photoelectron flux over a 109-day interval in late 2006. The code/model pairs we used do not completely reproduce the observed spectral and solar cycle variations in photoelectron power density. For the interval examined, 30 per cent of the variability in photoelectron power density with equivalent wavelengths between 18 and 45 nm was not captured in the code/model pairs. For equivalent wavelengths below ~ 16 nm, most of the variability was missed. This result implies that thermospheric model runs based on the solar irradiance models we tested systematically underestimate the energy input from ionizing radiation on solar rotation time scales.

Peterson, W. K. Bill; Solomon, Stanley; Warren, Harry; Fontenla, Juan; Woods, Thomas; Richards, Phil; Chamberlin, Phillip; Tobiska, W. Kent

2012-07-01

57

Late quaternary Mediterranean sapropels. III. Assessment of source of input and palaeotemperature as derived from biological markers  

SciTech Connect

Sources of input contributing to the organic matter of four different Mediterranean sapropels (S/sub 1/, S/sub 5/, S/sub 6/, S/sub 7/) are inferred from the relative distributions of terrigenous and marine biological markers in these Quaternary deposits. The relative terrigenous contribution does not vary significantly. Within the marine contribution there is a significant compositional variation. A contribution from dinoflagellates is relatively important in the S/sub 1/ sapropel, whereas sapropels S/sub 6/ and S/sub 7/ are characterized by a relatively large contribution from prymnesiophyte algae and planktonic cyanobacteria. The abundance of diatoms in sapropel S/sub 5/, as deduced from microscopic observations, is probably reflected by a high concentration of loliolide. Variations in sea-surface water temperatures can be deduced from the relative abundance of di- and triunsaturated C/sub 37/ ketones and from the relative abundance of esterified 27-nor-24-methylcholesta-5,22E-dien-3..beta..-ol and cholesta-5,22E-dien-3..beta..-ol. These two molecular temperature indices are consistent with the delta /sup 18/O record and with the pollen record of the sapropels investigated.

Ten Haven, H.L.; Baas, M.; Kroot, M.; De Leeuw, J.W.; Schenck, P.A.; Ebbing, J.

1987-04-01

58

Input \\/ Output Control Device Attached to the Electron-Ray Tube with a Dark Trace Recording for the Digital Image Treatment System  

Microsoft Academic Search

Description and operating principle of a video-control device for digital image treatment systems are given. The authors substantiate the choice of electron-ray tubes with dark-trace recording of the skiatron type for the control of the input-output operations carried out by slow mechanical devices.

V. G. Parusimov; A. V. Polyanskij; P. V. Nevodovskij; N. K. Zayets; A. A. Babichev

1984-01-01

59

Detection and characterization of local to regional groundwater inputs to rivers, lakes and oceans with electrical imaging (Invited)  

NASA Astrophysics Data System (ADS)

Surface water (SW) and groundwater (GW) interact at multiple levels in myriad settings and their interaction is an important hydrogeologic process that impacts ecological and biogeochemical functions. GW discharge and associated mixing with SW in these settings have been challenging to map with sufficient detail and coverage. Three examples are presented on the application of electrical resistivity imaging (ERI) for mapping GW discharge and for understanding SW-GW interactions: (1) a large regulated river, (2) several neighboring lakes, and (3) a fringing coral reef. (1) Time-lapse ERI was conducted at the Colorado River, Texas where the river stage varied by 0.7 m due to dam operations. Submerged and towed electrode cables were used to capture the subsurface mixing dynamics of SW and GW. Using temporal variability in electrical resistivity (ER) signatures, we identified a shallow well-flushed hyporheic zone, a transition zone where SW and GW mix, and a stable deep zone hosting only GW. (2) Towed ER surveys in alkaline lakes in the Nebraska Sand Hills helped distinguishing flow-through lakes, which have decreasing subsurface ER from GW inflow to outflow area, from pure GW discharge lakes, which have uniformly stratified increasing-with-depth ER profiles. (3) More than 30 km of ER profiles collected via towed surveys over a fringing coral reef in the Philippines identified areas of high ER within the reef that coincide with resistive zones in the seawater. Analysis of 222Rn of bottom waters and vertical conductivity-temperature-depth measurements show the persistence of fresh GW input into the ocean where low salinity and high 222Rn areas coincided with high ER areas. A 3D map showing sources and pathways for GW across the reef is developed. ERI is a powerful and convenient tool for mapping GW discharge and SW-GW interactions in rivers, lakes, and oceans.

Cardenas, M. B.; Befus, K. M.; Markowski, M.; Ong, J.; Zamora, P. B.; Siringan, F. P.; Zlotnik, V. A.

2010-12-01

60

Modelling purine derivative excretion in dairy goats: endogenous excretion and the relationship between duodenal input and urinary output.  

PubMed

To determine the endogenous contribution of purine derivatives (PD) to renal excretion and the urinary recovery of duodenal purine bases (PB), five dairy Granadina goats (initial weight ± s.e.: 38.6 ± 2.78 kg) were each fitted with a duodenal infusion catheter. Animals were offered ad libitum a mixed diet (75 : 25; alfalfa hay : concentrate), which was supplied in equal portions every 3 h. To label microbial PB, (15NH4)2SO4 was added to the concentrate. The lower enrichment of urinary PD (15N-allantoin) compared with duodenal PB enrichment confirmed the presence of an endogenous PD fraction (268.5 ± 21.98 ?mol/kg weight0.75 or 0.386 of the total PD excretion). The recovery of PD in urine and milk increased linearly in response to increasing amounts of duodenally infused RNA (starting on day 21 after parturition). On average, 0.74 of infused PB from RNA was recovered in urine. Milk PD constituted a minor (<0.01) fraction of the total PD excretion and this fraction decreased as the amount of infused PB increased. Our findings indicate that lactation in goats did not affect the urinary recovery of duodenal PB but increased the endogenous contribution to urinary excretion of PD. PMID:22444962

Mota, M; Balcells, J; Ozdemir Baber, N H; Bölüktepe, S; Belenguer, A

2008-01-01

61

Using Sediment Records to Reconstruct Historical Inputs Combustion-Derived Contaminants to Urban Airsheds/Watersheds: A Case Study From the Puget Sound  

NASA Astrophysics Data System (ADS)

Urban centers are major sources of combustion-derived particulate matter (e.g. black carbon (BC), polycyclic aromatic hydrocarbons (PAH), anhydrosugars) and volatile organic compounds to the atmosphere. Evidence is mounting that atmospheric emissions from combustion sources remain major contributors to air pollution of urban systems. For example, recent historical reconstructions of depositional fluxes for pyrogenic PAHs close to urban systems have shown an unanticipated reversal in the trends of decreasing emissions initiated during the mid-20th Century. Here we compare a series of historical reconstructions of combustion emission in urban and rural airsheds over the last century using sedimentary records. A complex suite of combustion proxies (BC, PAHs, anhydrosugars, stable lead concentrations and isotope signatures) assisted in elucidating major changes in the type of atmospheric aerosols originating from specific processes (i.e. biomass burning vs. fossil fuel combustion) or fuel sources (wood vs. coal vs. oil). In all studied locations, coal continues to be a major source of combustion-derived aerosols since the early 20th Century. Recently, however, oil and biomass combustion have become substantial additional sources of atmospheric contamination. In the Puget Sound basin, along the Pacific Northwest region of the U.S., rural locations not impacted by direct point sources of contamination have helped assess the influence of catalytic converters on concentrations of oil-derived PAH and lead inputs since the early 1970s. Although atmospheric deposition of lead has continued to drop since the introduction of catalytic converters and ban on leaded gasoline, PAH inputs have "rebounded" in the last decade. A similar steady and recent rise in PAH accumulations in urban systems has been ascribed to continued urban sprawl and increasing vehicular traffic. In the U.S., automotive emissions, whether from gasoline or diesel combustion, are becoming a major source of combustion-derived PM and BC to the atmosphere and have started to replace coal as the major source in some surficial reservoirs. This increased urban influence of gasoline and diesel combustion on BC emissions was also observed in Europe both from model estimates as well as from measured fluxes in recent lake sediments.

Louchouarn, P. P.; Kuo, L.; Brandenberger, J.; Marcantonio, F.; Wade, T. L.; Crecelius, E.; Gobeil, C.

2008-12-01

62

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

NASA Astrophysics Data System (ADS)

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

Huffman, French Tyler

63

Postmortem Validation of Imaging-Derived Formulas for Prediction of Fetal Lung Volume  

Microsoft Academic Search

Objective: To determine the validity of existing imaging-derived formulas for predicting the fetal lung volume (FLV). Methods: In a consecutive series of postmortem lungs without pulmonary anomalies, the observed FLV (FLVobs) after inflation was correlated with individual fetal variables used in imaging-derived formulas. In addition, FLVobs was correlated with the predicted FLV calculated according to these same formulas. Results: Postmortem

Monique E. De Paepe; Stephen R. Carr; John A. Cassese

2003-01-01

64

Multispectral image classification of MRI data using an empirically- derived clustering algorithm.  

National Technical Information Service (NTIS)

Multispectral image analysis of magnetic resonance imaging (MRI) data has been performed using an empirically-derived clustering algorithm. This algorithm groups image pixels into distinct classes which exhibit similar response in the T(sub 2) 1st and 2nd...

K. M. Horn G. C. Osbourn A. M. Bouchard J. A. Sanders

1998-01-01

65

A robust and fast imaging algorithm without derivative operations for UWB pulse radars  

Microsoft Academic Search

Target shape estimation with UWB pulse radars is promising as an imaging technique for household robots. We have already proposed a fast imaging algorithm, SEABED based on a reversible transform BST (Boundary Scattering Transform) between the received signals and the target shape. However the target image obtained by SEABED deteriorates in a noisy environment because it utilizes a derivative of

Shouhei Kidera; Takuya Sakamoto; Toru Sato

2006-01-01

66

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

PubMed

We have studied the cross section for electron trapping that occurs at the surfaces and interfaces of a variety of thin dielectric films (n-octane, methanol, n-butanol, and difluoromethane) that are grown on Kr buffer films. When such films are bombarded with electrons of very low incident energies (E less, similar 300 meV), charging cross sections up to the order of 10(-14) cm(2) are measured for submonolayer quantities of a variety of coadsorbed molecules: CH(3)I, CH(3)Br, CH(3)Cl, and CO(2). These huge cross sections are ascribed to the formation of image states at the dielectric film interfaces, which trap incoming electrons and, via coupling to the adsorbate electron affinity levels, dramatically enhance the capture probability. We have also shown that thin film dielectric layer structures can be created which display image-derived states, such as a "quantum well" in a sandwich structure with two "electron barrier" layers surrounding a Kr and adsorbate spacer film. These phenomena are shown to be of a general nature, occurring for a wide variety of molecular thin films, and depend on the dielectric constant and electron affinity of the selected species. We also report the absolute cross section for dissociative electron attachment of submonolayer CH(3)I adsorbed on Kr thin films. PMID:19044788

Jensen, E T; Sanche, L

2008-08-21

67

Guided Image Filtering  

Microsoft Academic Search

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

Kaiming He; Jian Sun; Xiaoou Tang

2010-01-01

68

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

69

Mirror-Image Matching and Mental Rotation Problem Solving by Baboons (Papio papio ): Unilateral Input Enhances Performance  

Microsoft Academic Search

Three experiments, using a matching-to-sample procedure, were conducted to examine hemispheric specialization in mirror-image discrimination and mental rotation in baboons (Papio papio). In Experiment 1, no significant difference was found in discrimination of mirror-image and asymmetric pattern stimuli. In Experiment 2, orientation discrimination was assessed within the left (LVF) and right (RVF) visual half-fields. An RVF advantage was found in

William D. Hopkins; Joël Fagot; Jacques Vauclair

1993-01-01

70

The Benefits of Using Short Interval Satellite Images to Derive Winds for Tropical Cyclones.  

National Technical Information Service (NTIS)

During the 1975, 1976, and 1977, NOAA's National Environmental Satellite Service and NASA's Goddard Space Flight Center conducted a cooperative program to determine the optimum resolution and frequency of satellite images for deriving winds to study and f...

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

1978-01-01

71

BIODISTRIBUTION AND PET IMAGING OF [18F]-FLUOROADENOSINE DERIVATIVES  

PubMed Central

Introduction: Many fluorinated analogues of adenosine nucleoside have been synthesized and studied as potential antitumor and antiviral agents. Earlier we reported radiosynthesis of 2?-deoxy-2?-[18F]fluoro-1-?-D-arabinofuranosyl-adenine ([18F]-FAA) and 3?-deoxy-3?-[18F]fluoro-1-?-D-xylofuranosyl-adenine ([18F]FXA). Now we report their in vivo studies including blood clearance, biodistribution and micro-PET imaging in tumor-bearing nude mice. Methods: Tumors were grown in six weeks old athymic nude mice (Harlan, Indianapolis, IN) by inoculation of HT-29 cells, wild type cells in the left flank and transduced cells with HSV-tk on the right flank. When the tumor was about 1 cm in size, animals were injected with these radiotracers for in vivo studies, including blood clearance, micro-PET imaging and biodistribution. Results: Uptake of [18F]FAA in tumor was 3.3-fold higher than blood, with highest uptake in the spleen. Maximum uptake of [18F]FXA was observed in the heart compared to other organs. There was no tumor uptake of [18F]FXA. Biodistribution results were supported by micro-PET images, which also showed very high uptake of [18F]FAA in spleen and visualization of tumors, and high uptake of [18F]FXA in the heart. Conclusion: These results suggest that [18F]FAA may be useful for tumor imaging, while [18F]FXA may have potential as a heart imaging agent with PET.

Alauddin, Mian M.; Shahinian, Antranik; Park, Ryan; Tohme, Michael; Fissekis, John D.; Conti, Peter S.

2007-01-01

72

Noise and Other Artifacts in OTF Derived from Image Scanning.  

PubMed

Image scanning here means measuring intensity distribution in the image of a pinhole or slit target with a moving knife edge or slit, with data recorded digitally. With the aid of some established methods for empirically estimating noise power spectra, combined with prior knowledge of the spectrum of a dominant noise process (usually shot noise of the PM tube), quantitative statistical formulae are developed that relate the magnitude of the fluctuating part of the answers to the several instrumental parameters that must be chosen in planning a measurement: the scan length, scanning speed, choice of target and choice of scanner, sampling rate, etc. Another noise mechanism, essentially peculiar to the computational method, is also examined briefly. The predictive formulae are compared statistically with a mass of experimental data, and it is concluded that they do predict, to within better than a factor of 2, the outcome of an actual measurement. Some sources of systematic error are also briefly discussed. PMID:20134915

Dutton, D

1975-02-01

73

Strategies for the generation of parametric images of [ 11C]PIB with plasma input functions considering discriminations and reproducibility  

Microsoft Academic Search

Pittsburgh compound B or [11C]PIB is an amyloid imaging agent which shows a clear differentiation between subjects with Alzheimer's disease (AD) and controls. However the observed signal difference in other forms of dementia such as dementia with Lewy bodies (DLB) is smaller, and mild cognitively impaired (MCI) subjects and some healthy elderly normals may show intermediate levels of [11C]PIB binding.

Paul Edison; David J. Brooks; Federico E. Turkheimer; Hilary A. Archer; Rainer Hinz

2009-01-01

74

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

75

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

PubMed Central

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

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

2012-01-01

76

Imaging and tracking of bone marrow-derived immune and stem cells.  

PubMed

Bone marrow (BM)-derived stem and immune cells play critical roles in maintaining the health, regeneration, and repair of many tissues. Given their important functions in tissue regeneration and therapy, tracking the dynamic behaviors of BM-derived cells has been a long-standing research goal of both biologists and engineers. Because of the complex cellular-level processes involved, real-time imaging technologies that have sufficient spatial and temporal resolution to visualize them are needed. In addition, in order to track cellular dynamics, special attention is needed to account for changes in the microenvironment where the cells reside, for example, tissue contraction, stretching, development, etc. In this chapter, we introduce methods for real-time imaging and longitudinal tracking of BM-derived immune and stem cells in in vivo three-dimensional (3-D) tissue environments with an integrated optical microscope. The integrated microscope combines multiple imaging functions derived from optical coherence tomography (OCT) and multiphoton microscopy (MPM), including optical coherence microscopy (OCM), microvasculature imaging, two-photon excited fluorescence (TPEF), and second harmonic generation (SHG) microscopy. Short- and long-term tracking of the dynamic behavior of BM-derived cells involved in cutaneous wound healing and skin grafting in green fluorescent protein (GFP) BM-transplanted mice is demonstrated. Methods and algorithms for nonrigid registration of time-lapse images are introduced, which allows for long-term tracking of cell dynamics over several months. PMID:23737096

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

2013-01-01

77

Systematic development of input-quantum-limited fluoroscopic imagers based on active-matrix flat-panel technology  

NASA Astrophysics Data System (ADS)

The development of fluoroscopic imagers exhibiting performance that is primarily limited by the noise of the incident x-ray quanta, even at very low exposures, remains a highly desirable objective for active matrix flat-panel technology. Previous theoretical and empirical studies have indicated that promising strategies to acheiving this goal include the development of array designs incorporating improved optical collection fill factors, pixel-level amplifiers, or very high-gain photoconductors. Our group is pursuing all three strategies and this paper describes progress toward the systematic development of array designs involving the last approach. The research involved the iterative fabrication and evaluation of a series of prototype imagers incorporating a promising high-gain photoconductive material, mercuric iodide (HgI2). Over many cycles of photoconductor deposition and array evaluation, improvements ina variety of properties have been observed and remaining fundamental challenges have become apparent. For example, process compatibility between the deposited HgI2 and the arrays have been greatly improved, while preserving efficient, prompt signal extraction. As a result, x-ray sensitivities within a factor of two of the nominal limit associated with the single-crystal form of HgI2 have been observed at relatively low electric fields (~0.1 to 0.6 V/?m), for some iterations. In addition, for a number of iterations, performance targets for dark current stability and range of linearity have been met or exceeded. However, spotting of the array, due to localized chemical reactions, is still a concern. Moreover, the dark current, uniformity of pixel response, and degree of charge trapping, though markedly improved for some iterations, require further optimization. Furthermore, achieving the desired performance for all properties simultaneously remains an important goal. In this paper, a broad overview of the progress of the research will be presented, remaining challenges in the development of this photoconductive material will be outlined, and prospects for further improvement will be discussed.

Antonuk, Larry E.; Zhao, Qihua; Su, Zhong; Yamamoto, Jin; El-Mohri, Youcef; Li, Yixin; Wang, Yi; Sawant, Amit R.

2004-05-01

78

Image segmentation using fuzzy rules derived from K-means clusters  

Microsoft Academic Search

Image segmentation is one of the most important steps in computerized systems for analyzing geographic map images. We present a segmentation technique, based on fuzzy rules derived from the K-means clusters, that is aimed at achieving humanlike performance. In this technique, the K-means clustering algorithm is first used to obtain mixed-class clusters of training examples, whose centers and variances are

Zheru Chi; Hong Yan

1995-01-01

79

Derivative spectra matching for wetland vegetation identification and by hyperspectral image  

NASA Astrophysics Data System (ADS)

In this paper, we reported some research result in applying hyperspectral remote sensing data in identification and classification of wetland plant species and associations. Hyperspectral data were acquired by Modular Airborne Imaging Spectrometer (MAIS) over Poyang Lake wetland, China. A derivative spectral matching algorithm was used in hyperspectral vegetation analysis. The field measurement spectra were as reference for derivative spectral matching. In the study area, seven wetland plant associations were identified and classified with overall average accuracy is 84.03%.

Wang, Jinnian; Zheng, Lanfen; Tong, Qingxi

1998-08-01

80

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

81

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

NASA Astrophysics Data System (ADS)

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

Hashimoto, Seitaro; Kose, Katsumi; Haishi, Tomoyuki

2012-05-01

82

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

83

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

84

Image-based display of activation patterns derived from scattered electrodes  

Microsoft Academic Search

Presentation of electrophysiologic data, such as activation patterns, can take many forms, the most common of which are hand or machine-drawn isochronal maps. The authors present an image-based method which provides accurate matching between electrophysiologic data and the anatomic sites from which the data were derived. This method is linear, simple, and straightforward to implement, and presents results in a

David S. Buckles; Matthew M. Wienecke; David A. Golod; Kenneth W. Hewett

1995-01-01

85

Resolution and shutter profile measurements with point source inputs for a microchannel-plate image intensifier (MCPII) with a 160-ps FWHM whole-image shutter  

NASA Astrophysics Data System (ADS)

The modulation transfer function (MTF) of a shuttered, 18-mm-diameter, proximity-focused 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 (off-off) for point-source (6-micrometers -diameter) illumination and 230 ps FWHM, -590 V gate pulses was measured to be inputs at several different locations on the MCPII and at different times in the shutering sequence. The best resolution, a 50% MTF 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 shutter speed (off-to-off) of the MCPII with a fully illuminated 18-mm-diameter photocathode was measured to be 270 ps and the FWHM was 160 ps.

Thomas, Matthew C.; Yates, George J.; Zagarino, Paul A.

1995-09-01

86

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

2013-07-08

87

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

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

2012-11-29

89

Practical method to derive nonlinear response functions of cameras for scientific imaging.  

PubMed

We developed a practical method to derive response functions that convert the amount of incident light to the counts of analog-to-digital conversion (A/D) of cameras for scientific imaging. In this method, we need a mechanism to accurately control the amount of incident light into cameras just within a limited dynamic range and at a limited number of steps. A variable brightness light source, which supplies the incident light into cameras, is also necessary, but we do not need to know its accurate brightness. Thus, this method enables us to derive the nonlinear response functions accurately with such a simple setup. PMID:21629319

Hanaoka, Yoichiro; Suzuki, Isao; Sakurai, Takashi

2011-06-01

90

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

91

An Evaluation of Stratosphere-Troposphere Ozone Exchange During TOPSE Using GOES Derived Product Images  

Microsoft Academic Search

The integration of newly developed GOES derived product images to TOPSE flight measurements allows for a more complete characterization of stratosphere-troposphere exchange along tropopause folds. The aircraft-based dIfferential absorption lidar (DIAL), ozone retrievals and co-located potential vorticity (PV) from the RUC-2 atmospheric model improves our understanding of the direct relationship between PV and stratospheric ozone. We shall examine the transport

A. J. Wimmers; J. L. Moody; E. V. Browell; J. W. Hair; C. F. Butler; W. B. Grant; M. A. Fenn; C. C. Schmidt; J. Li

2001-01-01

92

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

93

Reprocessing input data validation  

SciTech Connect

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

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

1990-01-01

94

Statistical tests for discriminating inaccurate input functions in dynamic mouse microPET studies  

Microsoft Academic Search

Image-derived input functions (EDIF) are desirable for quantifying biological functions in mouse microPET studies. Due to difficulties in taking many blood samples from each mouse, conventional IDIF validation method of comparing blood samples with IDIF in a single animal is not applicable. A new approach that requires statistical testing on data of multiple animals has been conceived and investigated for

Sung-Cheng Huang; Hsiao-Ming Wu; Kooresh Shoghi-Jadid; David Stout; Arion Chatziioannou

2003-01-01

95

Monitoring of agricultural drought in Poland using data derived from environmental satellite images  

NASA Astrophysics Data System (ADS)

In Poland one can observe a lack of sufficientcient amount of rainfall during plant growth season. This results in the occurrence of agricultural drought and the consequent drop in crop yields. For the early detection of drought, satellite images taken by environmental and meteorological satellites have been used. On the basis of these images various plant indices like NDVI, VCI and TCI have been determined. Analysis of changes in these indices allows preparation of maps showing the emergence and extent of drought. These vegetation indices were also used in the model of cereal yield forecast. Comparison of the results provided by the model show a high conformity with the results published by the Polish Central Statistical Office. Elaborated model estimating crop yield reduction due to drought, based on satellite-derived data allows venture of measures to mitigate results of drought and prevent the lowering yields by artificial irrigation.

Dabrowska-Zielinska, K.; Ciolkosz, A.; Malinska, A.; Bartold, M.

2012-06-01

96

Optimal filtering for systems with unknown inputs  

Microsoft Academic Search

An optimal filtering formula is derived for linear time-varying discrete systems with unknown inputs. By making use of the well-known innovations filtering technique, the derivation is an extension of a new observer design method for time-invariant deterministic systems with unknown inputs. The systems under consideration have the most general form. The derived optimal filter has a similar form to the

M. Hou; R. J. Patton

1998-01-01

97

Synthesis of fluorescent derivatives of praziquantel: cell-imaging and interaction with Schistosoma japonicum cercariae.  

PubMed

Schistosomiasis is one of the most burdensome of the neglected tropical diseases. Praziquantel is a recommended drug for treatment against all forms of schistosomiasis. To investigate the interaction between praziquantel and Schistosoma japonicum cercariae, two praziquantel derivatives (PZQ-2 and PZQ-3) and one praziquantel fluorescent derivative (PZQ-5) have been synthesized and characterized using nuclear magnetic resonance spectroscopy (NMR) and MS spectra. The cytotoxicity of PZQ-2, PZQ-3 and PZQ-5 was measured by performing the methyl thiazolyl tetrazolium (MTT) assay. The cell viability for them shows that the three compounds exhibit low cytotoxicity to HeLa cells. Cell imaging experiments demonstrate that PZQ-5 is biocompatible and cell-permeable, which indicates that PZQ-5 is suitable for studying their interaction. Confocal fluorescence microscopy revealed that PZQ-5 is mainly located at the cercarial tegument, which leads to the death of cercariae with the increase in time. PMID:23925274

Xie, Yunzhi; Li, Yibao; Wu, Yongquan; Liu, Chunhua; Li, Xiaokang; Li, Xun; Fan, Xiaolin

2013-09-28

98

Assessment of the potential for soil acidification in North India using the critical load approach and locally derived data for acidic and basic inputs.  

PubMed

Major ions (Cl-, NO3(-), SO4(2-), Ca2+, Mg2+, Na+, K+ and NH4(+)) were analysed in wet and dry deposition samples collected for 2 years using a polyethylene bottle and funnel collector at Agra in India. The deposition of ionic components (Ca2+ and Mg2+) derived from natural sources i.e. soil were higher than those of anthropogenic origin. In rainwater samples, non-sea-salt fraction was found to be 60-90%. In both wet and dry deposition Ca2+ was found to be the dominant ion which may be due to its large particle diameter. Results suggest that most of the acidity, which occurs due to NO3(-), SO4(2-) and Cl- is neutralized by alkaline constituents, which originate from airborne local soil and dust transported from the Thar desert. Acid neutralizing capacity of soil has also been quantified and found to be 33 x 10(3) neqg(-1). Using deposition data, the critical load for acidity of soil with respect to Ashoka and Eucalyptus was evaluated. The present level of deposition of S and N was found to be much lower than critical loads calculated for S and N. Critical load of exceedance in terms of deposition acidity was also calculated and found to be negative. This indicates that with respect to these species, the ecosystem is protected at the current level of deposition. PMID:14505724

Satsangi, Gur Sumiran; Lawrence, A J; Lakhani, A; Taneja, Ajay

2003-12-01

99

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

100

Stratospheric Images of Jupiter Derived from Hydrocarbon Emissions in Voyager 1 and 2 IRIS Spectra  

NASA Astrophysics Data System (ADS)

Spectroscopic data obtained by the Infrared Interferometer Spectrometer (IRIS) aboard Voyager 1 and 2 have been re-visited. Using the spectroscopic data and footprints of the IRIS aperture on the planet, we constructed images of the stratosphere of Jupiter at the emission bands of hydrocarbons including CH4, C2H6, C2H2, C3H4, C6H6, and C2H4. Thermal emission from the hydrocarbons on Jupiter originates from a broad region of the stratosphere extending from 1 to 10 millibars. We averaged the data using a bin of 20 degrees of longitude and latitudes in order to increase signal-to-noise ratios. The resultant images show interesting wave structure in Jupiter's stratosphere. Fourier transform analyses of these images yield wavenumbers 5 - 7 at mid-Northern and mid-Southern latitudes, and these results are different from those resulted from previous ground-based observations and recent Cassini CIRS, suggesting temporal variations on the stratospheric infrared pattern. The comparisons of the Voyager 1 and 2 spectra also show evidence of temporal intensity variations not only on the infrared hydrocarbon polar brightenings of hydrocarbon emissions but also on the stratospheric infrared structure in the temperate regions of Jupiter over the 4 month period between the two Voyager encounters. Short running title: Stratospheric Images of Jupiter derived from Voyager IRIS Spectra.

Seo, Haingja; Kim, Sang Joon; Choi, W. K.; Kostiuk, T.; Bjoraker, G.

2005-12-01

101

Optimal Image Subtraction Method: Summary Derivations, Applications, and Publicly Shared Application Using IDL  

NASA Astrophysics Data System (ADS)

To detect objects that vary in brightness or spatial coordinates over time, C. Alard and R. H. Lupton in 1998 proposed an "optimal image subtraction" (OIS) method that constructs a convolution kernel from a set of matching stars distributed across the two images to be subtracted. Using multivariable least squares, the kernel is derived and can be designed to vary by pixel coordinates across the convolved image. Local effects in the optics, including aberrations or other spatially sensitive perturbations to a perfect image, can be mitigated. This paper presents the specific systems of equations that originate from the OIS method. Also included is a complete description of the Gaussian components basis vectors used by Alard & Lupton to construct the convolution kernel. An alternative set of basis vectors, called the delta function basis, is also described. Important issues are addressed, including the selection of the matching stars, differential background correction, constant photometric flux, contaminated pixel masking, and alignment at the subpixel level. Computer algorithms for the OIS method were developed, written using the Interactive Data Language (IDL), and applications demonstrating these algorithms are presented.

Miller, J. Patrick; Pennypacker, C. R.; White, Graeme L.

2008-04-01

102

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

PubMed

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

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

2013-10-01

103

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.

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

2012-01-01

104

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

105

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.

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

2013-01-01

106

Evaluating the diagnostic and chemotherapeutic potential of vancomycin-derived imaging conjugates.  

PubMed

The main use of glycopeptide antibiotics is treatment of infections which are resistant to the commonly used ?- lactam antibiotics. Antitumor activity has also been reported for some glycopeptide antibiotics like bleomycin. In the present study we investigated the chemotherapeutic and diagnostic potential of two imaging agent derivatives of the glycopeptide antibiotic vancomycin. For the first conjugate, vancomycin was coupled to the fluorescent dye rhodamine, used in confocal laser scanning microscopy (CLSM) and fluorescence-activated cell sorting (FACS). The second conjugate consisted of vancomycin coupled to gadolinium-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (GdDOTA), a magnetic resonance imaging (MRI) contrast agent. The cellular uptake, specificity, and the accessibility by imaging methods of the two vancomycin conjugates was evaluated on 8 human cell lines (one benign, 7 malignant) by CLSM, FACS, and MRI experiments. Cytotoxicity of both vancomycin conjugates was determined in the FACS experiments with the annexin test indicating disrupted cell membranes. Some of the malignant cell lines showed clearly stronger uptake than the others and the benign cell line was among the cell lines with the lowest uptake. In the annexin test the cytotoxicity could be correlated to the conjugate uptake for all cell lines. The intracellular uptake of the vancomycin conjugates and the increased uptake into some of the malignant cell lines were interesting findings which should be further pursued. PMID:22741805

Sheikh, Sumbla; Sturzu, Alexander; Klose, Uwe; Echner, Hartmut; Deeg, Martin; Nägele, Thomas; Horger, Marius; Schwentner, Christian; Ernemann, Ulrike; Voelter, Wolfgang; Heckl, Stefan

2012-11-01

107

Noninvasive Detection and Imaging of Molecular Markers in Live Cardiomyocytes Derived from Human Embryonic Stem Cells  

PubMed Central

Raman microspectroscopy (RMS) was used to detect and image molecular markers specific to cardiomyocytes (CMs) derived from human embryonic stem cells (hESCs). This technique is noninvasive and thus can be used to discriminate individual live CMs within highly heterogeneous cell populations. Principal component analysis (PCA) of the Raman spectra was used to build a classification model for identification of individual CMs. Retrospective immunostaining imaging was used as the gold standard for phenotypic identification of each cell. We were able to discriminate CMs from other phenotypes with >97% specificity and >96% sensitivity, as calculated with the use of cross-validation algorithms (target 100% specificity). A comparison between Raman spectral images corresponding to selected Raman bands identified by the PCA model and immunostaining of the same cells allowed assignment of the Raman spectral markers. We conclude that glycogen is responsible for the discrimination of CMs, whereas myofibril proteins have a lesser contribution. This study demonstrates the potential of RMS for allowing the noninvasive phenotypic identification of hESC progeny. With further development, such label-free optical techniques may enable the separation of high-purity cell populations with mature phenotypes, and provide repeated measurements to monitor time-dependent molecular changes in live hESCs during differentiation in vitro.

Pascut, Flavius C.; Goh, Huey T.; Welch, Nathan; Buttery, Lee D.; Denning, Chris; Notingher, Ioan

2011-01-01

108

Generating Precise and Accurate Waveform-Derived Products From Medium-Footprint Geodetic Imaging Lidar  

NASA Astrophysics Data System (ADS)

NASA's airborne Laser Vegetation Imaging Sensor (LVIS) is a medium-high altitude (10 km above the ground), medium-footprint (10-25 m wide) wide-swath (2 km) geodetic, imaging laser altimeter system that digitally records the shapes of both the outgoing and returning laser pulses (waveforms) for every shot. Since 1997, the system has been used to acquire data in various locations including California, Arkansas, Costa Rica, New England, Maryland, Virginia and Greenland. It has also been used to prototype future spaceborne measurements (e.g., VCL, DESDynI), develop and refine data and return waveform processing algorithms, and showcase science applications of full-waveform altimetry. Data geolocation is achieved using NASA's Variable Estimation, Geolocation and Analysis Software (VEGAS). Using this software, we solve for and apply various system biases and parameters (e.g., angular offsets between the various reference frames on the aircraft and the timing offsets between the various data inputs) to generate the position of the laser footprint on the ground relative to a global reference frame such as WGS84. Waveforms are interpreted to identify the locations of different surfaces within the footprint including the mean ground, canopy top, and several metrics related to surface (including canopy) structure. For each data set, the precision and accuracy of the data products are assessed by intercomparison, and comparison to available in-situ data such as collected using GPS or higher-resolution laser altimetry. We will review the latest data processing procedures employed in the VEGAS system and the LVIS waveform interpretation approaches. The precision and accuracy of the data products from various locations will also be presented. Implications for future spaceborne missions recommended by the National Research Council (NRC) such as DESDynI, ICESat II and LIST will be discussed.

Hofton, M. A.; Blair, J. B.; Rabine, D. L.

2008-12-01

109

TART input manual  

SciTech Connect

The TART code is a Monte Carlo neutron/photon transport code that is only on the CRAY computer. All the input cards for the TART code are listed, and definitions for all input parameters are given. The execution and limitations of the code are described, and input for two sample problems are given. (WHK)

Kimlinger, J.R.; Plechaty, E.F.

1982-04-01

110

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

PubMed Central

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

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

2011-01-01

111

Technology and setup development for thermodiffusion welding of photocathode heteroepitaxial structures (HES) with glass input windows for image intensifier tubes (I2)  

NASA Astrophysics Data System (ADS)

In GaAs, InGaAs, InGaP-photocathodes for I2 to bond HES with input glass windows vacuum thermodiffusion welding (TDW) is used. By existing technology of TDW some problems are appeared, that connected with fragility, deformation, thermic matching of materials, also with thermic stresses in welded materials. In this report describe the methods of concrete problem-solving that attend TDW is described.

Ahmadeev, I.; Dolgyh, A.; Korsun, P.

2005-06-01

112

Tectonic features on Saturns satellites Dione and Rhea: Morphology and stratigraphy derived from Cassini ISS images  

NASA Astrophysics Data System (ADS)

Introduction: The second- and fourth-largest satellites of Saturn, Rhea (1528 km in diameter) and Dione (1124 km), harbor old, densely cratered surfaces but also show evidence of resurfacing through tectonism in the images taken by the two ISS cameras aboard the Cassini spacecraft since July 2004. On Dione, tectonic features are more widespread than on Rhea implying that geologic activity has been going on for a longer time, whereas on Rhea tectonic activity may have ceased early in its history. The tectonic inventory of both satellites incorporates (a) troughs (graben), (b) scarps, (c) ridges, (d) lineaments, and (e) plateaus on Dione. Procedure: In this paper we focus on the stratigraphic sequence of events which created these tectonic landforms, independent of specific stress origins which are the topic of further work. Our investigation is based on the global ISS image coverage at regional (150 - 500 m/pxl), and, for selected target areas, at high-resolution scale (< 50 m/pxl). Relative ages of tectonic landforms are constrained by (1) cross-cutting relationships, (2) by their degree of degradation, (3) and by their superimposed crater frequency. On Dione, the image resolutions are sufficient to examine stratigraphic relationships between tectonic features while on Rhea the areas affected by tectonism could not yet be observed so far at regional or high resolution. Stratigraphy: On both satellites, densely cratered plains are the dominant geologic units with inferred high ages of ~ 3 - 4.2 Gyr from cratering chronology models. Degraded, densely cratered graben in the high northern and southern latitudes on Dione were formed early in its history. On Rhea, ridges seen in stereo data also appear to be rather old features. Troughs and graben on Rhea's trailing hemisphere could be old, but further regional- and high-resolution imaging is needed for detailed investigations. On Dione's trailing hemisphere, a stratigraphic sequence of horsts, graben and scarps has been derived by mutual crosscutting and truncation. Three age groups can be observed: (1) Clusium and Carthage Fossae are the oldest, truncated by (2) Eurotas and Palatine Chasmata which in turn were truncated by (3) Padua Chasmata representing the youngest set of troughs. Time and duration of tectonic activity on the two satellites is difficult to determine because of uncertainties in cratering chronology models. In the Eurotas Chasmata region, for example, cratering models suggest either older tectonism of about ~ 3 Gyr, or even younger events of about ~ 1 Gyr. No age determinations of tectonic events on Rhea have been made so far due to lack of sufficient image coverage.

Wagner, R. J.; Neukum, G.; Stephan, K.; Giese, B.; Roatsch, T.; Wolf, U.; Porco, C. C.

2009-04-01

113

Ladar image recognition using synthetically derived discrete phase-amplitude filters in an optical correlator  

NASA Astrophysics Data System (ADS)

Correlation filters using computer-generated laser radar imagery have been constructed. This paper describes how the filters were constructed and reports correlating result with the synthetic imagery used in the training set, with real ladar imagery of equivalent targets, and with real ladar imagery of false targets. A comprehensive set of images was collected on the Eglin Test Range using a direct-detect scanning ladar mounted on a 100-meter tower. Various targets were placed on a large turntable and ladar range and intensity data were collected at various aspect and depression angles. The Irma scene generation software package was then used to generate synthetic ladar imagery for these targets at a similar set of range, aspect, and depression angles. Several different techniques were used to generate the filters and to process the imagery used in this research. This paper describes one of the most successful techniques. The paper provides details on the iterative approach used to generate composite filters, describes how they were applied, and compares the results produced from synthetic and real target imagery. This experiment was considered a success since the synthetically derived filters were capable of recognizing images of real targets while rejecting false targets.

Calloway, David; Goldstein, Dennis H.

2002-03-01

114

TLC-image analysis of non-chromophoric tuberostemonine alkaloid derivatives in Stemona species.  

PubMed

A simple, selective, precise, and accurate thin-layer chromatographic (TLC) image analytical method was developed and validated for simultaneous quantification of the major components in the root extracts of Stemona tuberosa (tuberostemonine, tuberostemonine N and neotuberostemonine)), and S. phyllantha (tuberostemonine and tuberostemonine A). The analysis was performed by TLC on silica gel 60 F254 aluminum plates using a mixture of dichloromethane: ethyl acetate: methanol: ammonium hydroxide (50:45:4:1) as mobile phase. Post-derivatization was employed by dipping the TLC plate into Dragendorff's reagent to visualize the spots. Image analysis of the scanned TLC plate was performed to detect the contents of tuberostemonine derivatives. The polynomial regression data for the calibration plots showed good linear relationships within the concentration range of 2-7 microg/spot. The method gave satisfactory precision, accuracy, selectivity and could simultaneously quantify tuberostemonine, tuberostemonine A, tuberostemonine N and neotuberostemonine. Dried powdered roots of S. tuberosa grown in Thailand contained 1.31 +/- 0.28, 1.63 +/- 0.18 and 1.24 +/- 0.27% tuberostemonine, tuberostemonine N, and neotuberostemonine (dry weight), respectively, while S. phyllantha roots contained 1.39 +/- 0.14% tuberostemonine and 0.39 +/- 0.08% tuberostemonine A (dry weight). The proposed method was simple, inexpensive, and more accessible to apply for many local authorities and small laboratories. PMID:24079167

Kongkiatpaiboon, Sumet; Keeratinijakal, Vichien; Gritsanapan, Wandee

2013-08-01

115

Swallow-tailed perylene derivative: a new tool for fluorescent imaging of lipid hydroperoxides.  

PubMed

A swallow-tailed perylene derivative including a triphenylphosphine moiety was synthesized and applied to the detection and the live-cell imaging of lipid hydroperoxides. The novel probe, named Spy-LHP, reacted rapidly and quantitatively with lipid hydroperoxides to form the corresponding oxide, Spy-LHPOx, which emits extremely strong fluorescence (Phi approximately 1) in the visible range (lambda(em) = 535 nm, 574 nm). Spy-LHP was highly selective for lipid hydroperoxides, and the addition of other reactive oxygen species (ROS) including hydrogen peroxides, hydroxyl radical, superoxide anion, nitric oxide, peroxynitrite, and alkylperoxyl radical, caused no significant increase in the fluorescence intensity. The probe exhibited good localization to cellular membranes and was successfully applied to the confocal laser scanning microscopy (CLSM) imaging of lipid hydroperoxides in live J774A.1 cells, in which lipid peroxidation was proceeded by the stimulation of 2,2-azobis(2-amidinopropane)dihydrochloride (AAPH). These findings establish Spy-LHP as a promising new tool for investigating the physiology of lipid hydroperoxides. PMID:18004455

Soh, Nobuaki; Ariyoshi, Tomoyuki; Fukaminato, Tuyoshi; Nakajima, Hizuru; Nakano, Koji; Imato, Toshihiko

2007-10-19

116

Doppler-Derived Trigger Signals for High-Frame-Rate Mouse Cardiovascular Imaging  

PubMed Central

The availability of an electrocardiogram (ECG) waveform in the adult mouse has permitted the measurement of fast, dynamic cardiac events where data acquisition is synchronized to the R-wave of the ECG waveform. These methods can easily attain one thousand frames/s at ultrasound frequencies greater than 20 MHz. With the heart being the first organ to develop, normal cardiovascular function is crucial to the viability of the developing embryo. Thus, translating such methodologies to analyze embryonic cardiovascular development would add crucial information in mouse models of congenital heart disease which are embryonic lethal. Obtaining an ECG signal from mouse embryos is impractical. Therefore, in this study, preliminary results are presented which derive a cardiac-trigger signal from Doppler blood-flow waveforms. A continuous wave 40 MHz Doppler ultrasound system was used to acquire the Doppler waveforms and a real-time algorithm was developed to process the Doppler waveforms and generate a trigger. Validation studies revealed that a heart rate can be reliably measured and that the Doppler trigger algorithm was robust enough to follow changes in the blood flow. Preliminary data showed that Doppler-derived triggers can be used for high-frame-rate prospective imaging of the early embryonic mouse heart.

Aristizabal, Orlando; Mamou, Jonathan; Turnbull, Daniel H.; Ketterling, Jeffrey A.

2009-01-01

117

Donor-Acceptor-Donor Fluorene Derivatives for Two-Photon Fluorescence Lysosomal Imaging  

PubMed Central

As part of a strategy to achieve large two-photon absorptivity in fluorene-based probes, a series of donor-acceptor-donor (D-A-D) type derivatives were synthesized and their two-photon absorption (2PA) properties investigated. The synthesis of D-A-D fluorophores was achieved by efficient preparation of key intermediates for the introduction of central electron acceptor groups. To accomplish the synthesis of two of the new derivatives, a high yield method for a one-step direct dibromomethylation of phenyl sulfide was developed. The linear and nonlinear optical properties, including UV-vis absorption, fluorescence emission, fluorescence anisotropy, and two-photon absorption (2PA), of the new D-A-D compounds were measured and compared to their D-A or D-D counterparts. Fully conjugated acceptor moieties in the center of the D-A-D fluorophore led to the greatest increase in the 2PA cross section, while weakly conjugated central acceptors exhibited only a modest increase in the 2PA cross section relative to D-A diploar analogs. Encapsulation of the new probes in Pluronic™ F 108NF micelles, and subsequent incubation in HCT 116 cells, resulted in very high lysosomal colocalization (>0.98 colocalization coefficient) relative to commercial Lysotracker™ Red, making the micelle-encapsulated dyes particularly attractive as fluorescent probes for two-photon fluorescence microscopy lysosomal imaging.

Yao, Sheng; Ahn, Hyo-Yang; Wang, Xuhua; Fu, Jie; Van Stryland, Eric W.; Hagan, David J.

2010-01-01

118

Molecular and Magnetic Resonance Imaging of Human Embryonic Stem Cell–Derived Neural Stem Cell Grafts in Ischemic Rat Brain  

Microsoft Academic Search

Real-time imaging of transplanted stem cells is essential for understanding their interactions in vivo with host environments, for tracking cell fate and function and for successful delivery and safety monitoring in the clinical setting. In this study, we used bioluminescence (BLI) and magnetic resonance imaging (MRI) to visualize the fate of grafted human embryonic stem cell (hESC)–derived human neural stem

Marcel M Daadi; Zongjin Li; Ahmet Arac; Brad A Grueter; Marc Sofilos; Robert C Malenka; Joseph C Wu; Gary K Steinberg

2009-01-01

119

Processing distributed inputs in coupled excitable lasers  

SciTech Connect

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

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

2007-11-15

120

Tycho Input Catalog.  

National Technical Information Service (NTIS)

The production of a specific Tycho input catalog for data reduction is presented. It contains about 2,000,000 objects at a magnitude value of B = 12.5 magnitude. The expected external errors of the Tycho input catalog positions are in the range of 1 to 2 ...

D. Egret P. Didelon B. J. Mclean

1989-01-01

121

Hyperpolarized (3)He magnetic resonance imaging-derived pulmonary pressure-volume curves.  

PubMed

We aimed to evaluate the potential for the use of hyperpolarized helium-3 magnetic resonance imaging (MRI) apparent diffusion coefficient (ADC) surrogates of alveolar size, together with literature-based morphological parameters in a theoretical model of lung mechanics to simulate noninvasive transpulmonary pressure-volume curves. Fourteen ex-smokers with chronic obstructive pulmonary disease (COPD) (n = 8 stage II, n = 6 stage III/IV COPD) and five age-matched never-smokers, provided written, informed consent and were evaluated at baseline and 26 + or - 2 mo later (n = 15 subjects) using plethysmography, spirometry, and (3)He MRI at 3.0 T. Total lung capacity, residual volume, and literature-based morphological parameters were used with alveolar volumes derived from (3)He ADC to simulate noninvasive pressure-volume curves. The resultant anterior-posterior transpulmonary pressure gradient was significantly decreased for stage II COPD (P < 0.01) and stage III COPD subjects (P < 0.001) compared with healthy volunteers. Both COPD subgroups showed increased alveolar radius compared with healthy subjects (P < 0.01, stage II COPD; P < 0.001, stage III COPD). In addition, surface area and surface tension were significantly increased in stage III COPD compared with healthy volunteers (P < 0.01). These results suggest that (3)He MRI provides a potential noninvasive approach to evaluate lung mechanics regionally and further supports the use of ADC values as a regional noninvasive probe of pulmonary microstructure and compliance. PMID:20538846

Choy, Stephen; Wheatley, Andrew; McCormack, David G; Parraga, Grace

2010-06-10

122

Ferrioxamine B derivatives as hepatobiliary contrast agents for magnetic resonance imaging.  

PubMed

Succinyl (SDF), phenylsuccinyl (PSDF), glutaryl (GDF), and phenylglutaryl (PGDF) derivatives of desferrioxamine B (DF) have been synthesized. In rats given the 59Fe(III) chelates of each these ligands at tracer levels, 82-94% of the 59Fe was eliminated within 1-2 days. 59Fe given as DF, SDF, and GDF chelates was excreted primarily in the urine, while nearly 50% of that given as PSDF and PGDF was excreted in the feces. Correspondingly, Fe-DF, Fe-SDF, and Fe-GDF (0.2 mmol/kg) produced early, marked renal, but no gastrointestinal magnetic resonance imaging (MRI) enhancement. Fe-PSDF and Fe-PGDF (0.2 mmol/kg) produced marked and rapid MRI enhancement of the upper small intestine. In animals with cannulated bile ducts, 59Fe from 59Fe-PGDF (carrier added, 0.1 mmol/kg) appeared rapidly in the collected bile, but not in the intestinal contents, proving that the contrast agent reaches the bowel via the bile. These changes in the excretion and MRI enhancement patterns brought about by the presence of a phenyl substituent apparently were not related to changes in lipophilicity or protein binding. PMID:1798398

Muetterties, K A; Hoener, B A; Engelstad, B L; Tongol, J M; Wikstrom, M G; Wang, S C; Eason, R G; Moseley, M E; White, D L

1991-11-01

123

Imaging perylene derivatives on rutile TiO2(110) by noncontact atomic force microscopy  

NASA Astrophysics Data System (ADS)

The adsorption of 3,4,9,10-perylene tetracarboxylic diimide derivative molecules on the rutile TiO2(110) surface was investigated by noncontact atomic force microscopy and density-functional theory (DFT) calculations. After submonolayer deposition, individual molecules are observed to adsorb with their main axis aligned along the [001] direction and centered on top of the bridging oxygen rows. Depending on the tip termination, two distinctly different molecular contrasts are achieved. In the first mode, the molecules are imaged as bright elongated features, while in another mode the molecules appear with a bright rim and a dark bow-shaped center. Comparison with the defect density on the bare TiO2(110) surface suggests that the molecules preferentially anchor to surface defects. Our DFT calculations reveal details of the molecular adsorption position, confirming the experimentally observed adsorption on top of the bridging oxygen rows. The DFT results indicate that diffusion along the rows should be quite easily possible, while diffusion perpendicular to the rows seems to be hindered by a significant energy barrier.

Schütte, J.; Bechstein, R.; Rahe, P.; Rohlfing, M.; Kühnle, A.; Langhals, H.

2009-01-01

124

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

Microsoft Academic Search

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

M. C. Thomas; G. J. Yates; P. Zagarino

1995-01-01

125

Aerosol input to the South China Sea: Results from the MODerate Resolution Imaging Spectroradiometer, the Quick Scatterometer, and the Measurements of Pollution in the Troposphere Sensor  

Microsoft Academic Search

Data from the MODerate Resolution Imaging Spectro-radiometer (MODIS) and other satellite sensors in 2002–2004 indicate that, in addition to locally produced sea-salt particles, aerosols from various remote sources also find their ways to the South China Sea, including industrial\\/urban pollution in eastern China, wind-blown dust from Asian deserts and biomass burning in Sumatra and Borneo. Among these sources, anthropogenic aerosols

I-I Lin; Jen-Ping Chen; George T. F. Wong; Chih-Wei Huang; Chun-Chi Lien

2007-01-01

126

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

PubMed

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

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

2012-07-01

127

Input and Interaction.  

ERIC Educational Resources Information Center

Examines the connection between empirical studies of interaction involving second-language learners and the specific claims of Krashen's Input Hypothesis, as modified by Chaudron, White, and Swain. (36 references) (GLR)

Young, Richard

1988-01-01

128

Input: A Communication Experience  

ERIC Educational Resources Information Center

Reports on Project Input at the Hoffman, Minnesota High School which gives students experience in using oral language with residents in a nursing home, retarded children and adults, and pupils in an elementary school. (RB)

Westbrock, Leon

1973-01-01

129

High-resolution Atlases of Mimas, Tethys, and Iapetus derived from Cassini-ISS images  

Microsoft Academic Search

The Cassini Imaging Science Subsystem (ISS) acquired 282, 258, and 513 high-resolution images (<800m\\/pixel) of Mimas, Tethys, and Iapetus, respectively, during two close flyby of Tethys and Iapetus and eight non-targeted flybys between 2004 and 2007. We combined these images with lower-resolution Cassini images and others taken by Voyager cameras to produce high-resolution semi-controlled mosaics of Mimas, Tethys, and Iapetus.

Th. Roatsch; M. Wählisch; A. Hoffmeister; E. Kersten; K.-D. Matz; F. Scholten; R. Wagner; T. Denk; G. Neukum; P. Helfenstein; C. Porco

2009-01-01

130

Modeling Stokes flow in real pore geometries derived by high resolution micro CT imaging  

NASA Astrophysics Data System (ADS)

Meanwhile, numerical modeling of rock properties forms an important part of modern petrophysics. Substantially, equivalent rock models are used to describe and assess specific properties and phenomena, like fluid transport or complex electrical properties. In recent years, non-destructive computed X-ray tomography got more and more important - not only to take a quick and three dimensional look into rock samples but also to get access to in-situ sample information for highly accurate modeling purposes. Due to - by now - very high resolution of the 3D CT data sets (micron- to submicron range) also very small structures and sample features - e.g. micro porosity - can be visualized and used for numerical models of very high accuracy. Special demands even arise before numerical modeling can take place. Inappropriate filter applications (e.g. improper type of filter, wrong kernel, etc.) may lead to a significant corruption of spatial sample structure and / or even sample or void space volume. Because of these difficulties, especially small scale mineral- and pore space textures are very often lost and valuable in-situ information is erased. Segmentation of important sample features - porosity as well as rock matrix - based upon grayscale values strongly depends upon the scan quality and upon the experience of the application engineer, respectively. If the threshold for matrix-porosity separation is set too low, porosity can be quickly (and even more, due to restrictions of scanning resolution) underestimated. Contrary to this, a too high threshold over-determines porosity and small void space features as well as interfaces are changed and falsified. Image based phase separation in close combination with "conventional" analytics, as scanning electron microscopy or thin sectioning, greatly increase the reliability of this preliminary work. For segmentation and quantification purposes, a special CT imaging and processing software (Avizo Fire) has been used. By using this tool, 3D rock data can be assessed and interpreted by petrophysical means. Furthermore, pore structures can be directly segmented and hence could be used for so called image based modeling approach. The special XLabHydro module grants a finite volume solver for the direct assessment of Stokes flow (incompressible fluid, constant dynamic viscosity, stationary conditions and laminar flow) in real pore geometries. Nevertheless, also pore network extraction and numerical modeling with standard FE or lattice Boltzmann solvers is possible. By using the achieved voxel resolution as smallest node distance, fluid flow properties can be analyzed even in very small sample structures and hence with very high accuracy, especially with interaction to bigger parts of the pore network. The so derived results in combination with a direct 3D visualization within the structures offer great new insights and understanding in range of meso- and microscopic pore space phenomena.

Halisch, M.; Müller, C.

2012-04-01

131

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

132

Deriving star-formation and extinction in normal galaxies from H(alpha) and Paschen(beta) imaging  

Microsoft Academic Search

We propose to derive spatial maps of extinction corrected ionizing radiation and dust columns using narrow-band imaging in H(alpha) and Paschen(beta) of normal, nearby galaxies. This is possible because the intrinsic line ratios are insensitive to temperature and densities in HII regions. Comparison of observed line ratios to the intrinsic ones, using the extinction law, will yield column densities of

Sangeeta Malhotra; Daniel Dale; James Rhoads; George Helou; Robert Kennicutt; Deidre Hunter

1999-01-01

133

11C-labeled stilbene derivatives as A?-aggregate-specific PET imaging agents for Alzheimer’s disease  

Microsoft Academic Search

A series of stilbene derivatives as potential diagnostic imaging agents targeting amyloid plaques in Alzheimer’s disease (AD) were synthesized and evaluated. The syntheses of the stilbenes were successfully achieved by a simple Wadsworth-Emmons reaction between diethyl (4-nitrobenzyl)phosphonate and 4-methoxybenzaldehyde. 4-N,N-dimethylamino-4?-methyoxy and the corresponding 4-N-monomethylamino-, 4?-hydroxy stilbenes showed good binding affinities towards A? aggregates in vitro (Ki < 10 nM). The

Masahiro Ono; Alan Wilson; Jose Nobrega; David Westaway; Paul Verhoeff; Zhi-Ping Zhuang; Mei-Ping Kung; Hank F. Kung

2003-01-01

134

Data-driven inversion\\/depth imaging derived from approximations to one-dimensional inverse acoustic scattering  

Microsoft Academic Search

This paper presents a new mathematical framework based on inverse scattering for the estimation of the scattering potential and its nature of a one-dimensional acoustic layered medium from single scattering data. Given the Born potential associated with constant-velocity imaging of the single scattering data, a closed-form implicit expression for the scattering potential is derived in the WKBJ and eikonal approximations.

Lasse Amundsen; Arne Reitan; Hans Kr Helgesen; Børge Arntsen

2005-01-01

135

High-resolution atlas of Rhea derived from Cassini-ISS images  

NASA Astrophysics Data System (ADS)

The Cassini Imaging Science Subsystem (ISS) acquired 370 high-resolution images (<500 m/pixel) of Rhea during two close flybys and 9 non-targeted flybys between 2004 and 2010. We combined these images with lower-resolution Cassini images and others taken by the Voyager cameras to produce a high-resolution semi-controlled mosaic of Rhea. This global mosaic is the baseline for a high-resolution Rhea atlas. The nomenclature used in this atlas was proposed by the Cassini imaging team and approved by the International Astronomical Union (IAU). The atlas is available to the public through the Imaging Team's website and the Planetary Data System . This atlas completes the series of the atlases of the Saturnian medium-sized satellites Mimas, Enceladus, Tethys, Dione, Rhea, and Iapetus.

Roatsch, Th.; Kersten, E.; Wählisch, M.; Hoffmeister, A.; Matz, K.-D.; Scholten, F.; Wagner, R.; Denk, T.; Neukum, G.; Porco, C. C.

2012-02-01

136

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

137

Deriving High-Level Concepts Using Fuzzy-ID3 Decision Tree for Image Retrieval  

Microsoft Academic Search

To improve the retrieval accuracy of content-based image retrieval, an important task is to reduce the 'semantic gap' between low-level image features and the richness of human semantics. In this paper, we present a region-based image retrieval system with high-level semantic concepts used. The contribution of the paper is two-fold. First, salient low-level features are extracted from arbitrary-shaped regions. Second,

Ying Liu; Dengsheng Zhang; Guojun Lu; Wei-Ying Ma

2005-01-01

138

Variable structure control of non-simple input systems  

Microsoft Academic Search

To date the variable structure control (VSC) technique has been used to control systems that are affected by a forcing function that is composed solely of an input u (i.e. simple input systems). However, some systems are affected by forcing functions that are composed of an input plus its derivatives and integrals (i.e. non-simple input systems).A procedure is presented that

G. WALKER

1991-01-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

140

Tutorial on Exit Pupils and Eye Rotation with Virtual Image Optical Displays.  

National Technical Information Service (NTIS)

Exit pupils of virtual image optical displays and eye entrance pupils and how their sizes and relative positions influence light input to the eye are discussed. Equations based on simplifying assumptions about the eye and its rotational behavior are deriv...

H. C. Self

1992-01-01

141

Radioiodinated phenoxyacetic acid derivatives as potential brain imaging agents. I. Efficient synthesis via trimethylsilyl intermediates.  

PubMed

The usefulness of radioiodination via demetallation of aryltrimethylsilanes was demonstrated. The radioiodination reaction was found to be very rapid and the regiospecific incorporation of radioiodine could be carried out with high radiochemical yields and high radiospecific activity. 125I-Labeled dimethylaminoethyl iodophenoxyacetate derivatives (5a--e), dimethylaminoethyl iodophenoxyacetamide derivatives (7a--c), iodophenoxyethyl ethylenediamine derivatives (9,14) and an iodophenoxyethylpiperazine derivative (18) were efficiently synthesized from the corresponding aryltrimethylsilyl intermediates (4a--e, 6a--c, 8, 13, 17) by this method. PMID:2605676

Ohmomo, Y; Okuyama, S; Magata, Y; Ueno, Y; Tanaka, C; Yokoyama, A

1989-09-01

142

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

Microsoft Academic Search

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

P. Reimer; T. Allkemper; G. Schuierer; P. E. Peters

1996-01-01

143

A derivative-aided hyperspectral image analysis system for land-cover classification  

Microsoft Academic Search

The large number of spectral bands in hyperspectral data seriously complicates their use for classification. Selection of a useful subset of bands or derived features (spectral ratios, differences, derivatives) is always desirable, strongly affects the accuracy of the classification, and is often a practical necessity to keep the processing speed and memory requirements under control. This paper examines one possible

Fuan Tsai; William D. Philpot

2002-01-01

144

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

PubMed Central

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

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

2013-01-01

145

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

PubMed

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 (123)I-labeled pyridyl benzofuran derivatives as SPECT probes for A? imaging. The formation of a pyridyl benzofuran backbone was accomplished by Suzuki coupling. [(123)I/(125)I]-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 [(123)I]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). [(125)I]8 displayed the quickest clearance from the brain (1.30% ID/g at 60 min). SPECT/CT with [(123)I]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 [(123)I]8 to A? plaques in the Tg2576 mouse brain. These combined results warrant further investigation of [(123)I]8 as a SPECT imaging agent for visualizing A? plaques in the AD brain. PMID:24058519

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

2013-09-13

146

Yet another user input method: Accelerometer assisted single key input  

Microsoft Academic Search

In this paper we present YAUIM - yet another user input method. YAUIM is an alternative user input mechanism to the conventional keyboard, mouse, and touch screen inputs. It utilizes the embedded accelerometer to detect device movements and tilt positions to enable user inputs. Accelerometers embedded in devices have been used to identify meaningful combinations of movements for gaming and

Chunming Gao; Robert Pastel; Jindong Tan

2010-01-01

147

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

PubMed Central

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

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

2013-01-01

148

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

Microsoft Academic Search

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

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

2002-01-01

149

Definition of Energy Input: Operation ICE CAP.  

National Technical Information Service (NTIS)

Photometric and Image Intensified TV (IITV) measurements of auroral precipitation patterns and energy input were made at Poker Flats, Alaska in support of the 1972 ICE CAP series of rocket experiments. Photometric data was obtained on 4278A, 4861A and 630...

R. D. Sears

1972-01-01

150

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

NASA Astrophysics Data System (ADS)

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

Magland, Jeremy F.; Wehrli, Felix W.

2008-04-01

151

Identification of Controlled-Complexity Thermal Therapy Models Derived from Magnetic Resonance Thermometry Images  

PubMed Central

Medical imaging provides information valuable in diagnosis, planning, and control of therapies. In this paper, we develop a method that uses a specific type of imaging—the magnetic resonance thermometry—to identify accurate and computationally efficient site and patient-specific computer models for thermal therapies, such as focused ultrasound surgery, hyperthermia, and thermally triggered targeted drug delivery. The developed method uses a sequence of acquired MR thermometry images to identify a treatment model describing the deposition and dissipation of thermal energy in tissues. The proper orthogonal decomposition of thermal images is first used to identify a set of empirical eigenfunctions, which captures spatial correlations in the thermal response of tissues. Using the reduced subset of eigenfunction as a functional basis, low-dimensional thermal response and the ultrasound specific absorption rate models are then identified. Once identified, the treatment models can be used to plan, optimize, and control the treatment. The developed approach is validated experimentally using the results of MR thermal imaging of a tissue phantom during focused ultrasound sonication. The validation demonstrates that our approach produces accurate low-dimensional treatment models and provides a convenient tool for balancing the accuracy of model predictions and the computational complexity of the treatment models.

Niu, Ran; Skliar, Mikhail

2011-01-01

152

Identification of controlled-complexity thermal therapy models derived from magnetic resonance thermometry images.  

PubMed

Medical imaging provides information valuable in diagnosis, planning, and control of therapies. In this paper, we develop a method that uses a specific type of imaging--the magnetic resonance thermometry--to identify accurate and computationally efficient site and patient-specific computer models for thermal therapies, such as focused ultrasound surgery, hyperthermia, and thermally triggered targeted drug delivery. The developed method uses a sequence of acquired MR thermometry images to identify a treatment model describing the deposition and dissipation of thermal energy in tissues. The proper orthogonal decomposition of thermal images is first used to identify a set of empirical eigenfunctions, which captures spatial correlations in the thermal response of tissues. Using the reduced subset of eigenfunction as a functional basis, low-dimensional thermal response and the ultrasound specific absorption rate models are then identified. Once identified, the treatment models can be used to plan, optimize, and control the treatment. The developed approach is validated experimentally using the results of MR thermal imaging of a tissue phantom during focused ultrasound sonication. The validation demonstrates that our approach produces accurate low-dimensional treatment models and provides a convenient tool for balancing the accuracy of model predictions and the computational complexity of the treatment models. PMID:22073204

Niu, Ran; Skliar, Mikhail

2011-11-02

153

Estimation of tensors and tensor-derived measures in diffusional kurtosis imaging.  

PubMed

This article presents two related advancements to the diffusional kurtosis imaging estimation framework to increase its robustness to noise, motion, and imaging artifacts. The first advancement substantially improves the estimation of diffusion and kurtosis tensors parameterizing the diffusional kurtosis imaging model. Rather than utilizing conventional unconstrained least squares methods, the tensor estimation problem is formulated as linearly constrained linear least squares, where the constraints ensure physically and/or biologically plausible tensor estimates. The exact solution to the constrained problem is found via convex quadratic programming methods or, alternatively, an approximate solution is determined through a fast heuristic algorithm. The computationally more demanding quadratic programming-based method is more flexible, allowing for an arbitrary number of diffusion weightings and different gradient sets for each diffusion weighting. The heuristic algorithm is suitable for real-time settings such as on clinical scanners, where run time is crucial. The advantage offered by the proposed constrained algorithms is demonstrated using in vivo human brain images. The proposed constrained methods allow for shorter scan times and/or higher spatial resolution for a given fidelity of the diffusional kurtosis imaging parametric maps. The second advancement increases the efficiency and accuracy of the estimation of mean and radial kurtoses by applying exact closed-form formulae. PMID:21337412

Tabesh, Ali; Jensen, Jens H; Ardekani, Babak A; Helpern, Joseph A

2010-10-28

154

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

Microsoft Academic Search

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

Alexandra Duel-hallen

1992-01-01

155

(99m)Tc-labeled dibenzylideneacetone derivatives as potential SPECT probes for in vivo imaging of ?-amyloid plaque.  

PubMed

Four (99m)Tc-labeled dibenzylideneacetone derivatives and corresponding rhenium complexes were successfully synthesized and biologically evaluated as potential imaging probes for A? plaques using SPECT. All rhenium complexes (5a-d) showed affinity for A?(1-42) aggregates (Ki = 13.6-120.9 nM), and selectively stained the A? plaques on brain sections of transgenic mice. Biodistribution in normal mice revealed that [(99m)Tc]5a-d exhibited moderate initial uptake (0.31%-0.49% ID/g at 2 min) and reasonable brain washout at 60 min post-injection. Although additional optimizations are still needed to facilitate it's penetration through BBB, the present results indicate that [(99m)Tc]5a may be a potential SPECT probe for imaging A? plaques in Alzheimer's brains. PMID:23644192

Yang, Yanping; Cui, Mengchao; Jin, Bing; Wang, Xuedan; Li, Zijing; Yu, Pingrong; Jia, Jianhua; Fu, Hualong; Jia, Hongmei; Liu, Boli

2013-04-06

156

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

157

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

NASA Astrophysics Data System (ADS)

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

Tun, Samuel D.; Vourlidas, A.

2013-04-01

158

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

159

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

2013-10-11

160

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

161

Brachial plexus MR imaging: accuracy and reproducibility of DTI-derived measurements and fibre tractography at 3.0-T  

Microsoft Academic Search

Objective  To estimate intrastudy, intraobserver and interobserver reproducibility of DTI-derived measurements and fibre tractography\\u000a (FT) at 3.0 T MR imaging in subjects without known brachial plexus pathology.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  IRB approval and written informed consent were obtained. Forty healthy volunteers underwent bilateral 3.0-T DTI of the brachial\\u000a plexus. Postprocessing included FT and analysis of fractional anisotropy (FA) and apparent diffusion coefficient (ADC). Four\\u000a authors

Alberto Tagliafico; Massimo Calabrese; Matteo Puntoni; Daniele Pace; Gabriella Baio; Carlo Emanuele Neumaier; Carlo Martinoli

2011-01-01

162

Derivation of new emission factors for quantification of mass emissions when using optical gas imaging for detecting leaks.  

PubMed

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 using a combination of field data and Monte Carlo statistical simulation techniques. These newly derived leak/no-leak emission factors are designed to replace the U.S. Environment Protection Agency (EPA) 1995 Protocol factors, which were based on Method 21 monitoring of leaks at "uncontrolled" facilities. The emission factors published in the 1995 Protocol have not been updated since the 1970s. This derivation is based on results where the authors document the use of a Monte Carlo simulation technique to quantify the required leak detection thresholds that provide equal--or better--environmental benefits for an AWP. The use of these newly derived emission factors is demonstrated for different methods of computing fugitive emissions from a hypothetical model refinery. The resulting facility emissions calculated by using these new emission factors is compared with the existing emission estimation methods provided in the EPA 1995 Protocol. The results demonstrate that the new emission factors provide an emission estimate that is the closest to that obtained from the direct determination of total emissions by Monte Carlo simulations. PMID:17912925

Lev-On, Miriam; Epperson, David; Siegell, Jeffrey; Ritter, Karin

2007-09-01

163

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

164

Quantifying bedside-derived imaging of microcirculatory abnormalities in septic patients: a prospective validation study  

Microsoft Academic Search

INTRODUCTION: The introduction of orthogonal polarization spectral (OPS) imaging in clinical research has elucidated new perspectives on the role of microcirculatory flow abnormalities in the pathogenesis of sepsis. Essential to the process of understanding and reproducing these abnormalities is the method of quantification of flow scores. METHODS: In a consensus meeting with collaboraters from six research centres in different fields

E Christiaan Boerma; Keshen R Mathura; Peter HJ van der Voort; Peter E Spronk; Can Ince

2005-01-01

165

BrainMap: A Database of Functional Neuroanatomy Derived from Human Brain Images.  

National Technical Information Service (NTIS)

The goal of the BrainMap project is to promote efficient compilation, analysis, and dissemination of the rapidly growing body of information about the functional organization of the human brain which can be provided by medical imaging techniques such as P...

1991-01-01

166

Deriving a blood-mimicking fluid for particle image velocimetry in sylgard-184 vascular models  

Microsoft Academic Search

A new blood-mimicking fluid (BMF) has been developed for particle image velocimetry (PIV), which enables flow studies in vascular models (phantoms). A major difficulty in PIV that affects measurement accuracy is the refraction and distortion of light passing through the interface between the model and the fluid, due to the difference in refractive index (n) between the two materials. The

Majid Y. Yousif; David W. Holdsworth; Tamie L. Poepping

2009-01-01

167

A High-Resolution Imaging Algorithm without Derivatives Based on Waveform Estimation for UWB Radars  

Microsoft Academic Search

SUMMARY UWB pulse radars enable us to measure a target location with high range-resolution, and so are applicable for measurement systems for robots and automobile. We have already proposed a robust and fast imaging algorithm with an envelope of circles, which is suitable for these applications. In this method, we determine time delays from received sig- nals with the matched

Shouhei Kidera; Takuya Sakamoto; Toru Sato

2007-01-01

168

The methods research of deriving bamboo information based on IKONOS image  

Microsoft Academic Search

Bamboo is an important forest resource at sub-tropical regions in China, which continuous expansion has taken place in China during the last 20 years. Monitoring its distribution has important significance. It provide a possibility that we can extract accurate information among vegetation types as result of detailed texture features, patterns, optical information can be obtained from IKONOS image. In this

Zheng Guo; Hong Jiang; Jian Chen; Miaomiao Cheng; Zishan Jiang

2009-01-01

169

An assessment of Multiangle Imaging Spectroradiometer (MISR) stereo-derived cloud top heights and cloud top winds using ground-based radar, lidar, and microwave radiometers  

Microsoft Academic Search

(1) In this article stereoscopically derived cloud top heights and cloud winds estimated from the Multiangle Imaging Spectroradiometer (MISR) are assessed. MISR is one of five instruments on board the NASATerra satellite. The cloud top height assessment is based on a comparison of more than 4 years of MISR retrievals with that derived from ground-based radar and lidar systems operated

Roger T. Marchand; Thomas P. Ackerman; Catherine Moroney

2007-01-01

170

An assessment of Multiangle Imaging Spectroradiometer (MISR) stereo-derived cloud top heights and cloud top winds using ground-based radar, lidar, and microwave radiometers  

Microsoft Academic Search

In this article stereoscopically derived cloud top heights and cloud winds estimated from the Multiangle Imaging Spectroradiometer (MISR) are assessed. MISR is one of five instruments on board the NASA Terra satellite. The cloud top height assessment is based on a comparison of more than 4 years of MISR retrievals with that derived from ground-based radar and lidar systems operated

Roger T. Marchand; Thomas P. Ackerman; Catherine Moroney

2007-01-01

171

Nuclear inputs for nucleosynthesis applications  

NASA Astrophysics Data System (ADS)

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.; Hilaire, S.; Chamel, N.

2009-01-01

172

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

173

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

NASA Astrophysics Data System (ADS)

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 the DEMs, we adjust their longitude, latitude and altitude over motionless areas. The uncertainty of the thickness change measurement is greatly reduced by averaging over areas covering altitude intervals of 50 m. Comparisons with topographic profiles and a differential DEM from aerial photographs obtained on the Mer de Glace indicate an overall accuracy of 1 m for the thickness change measurement. Below 2100 m, satellite DEMs show an evolution of the thinning rate from 1 +/- 0.4 m.a-1 (years 1979-1994) to 4.1 +/- 1.7 m.a-1 (2000-2003).

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

2004-09-01

174

High-resolution Vesta Low Altitude Mapping Orbit Atlas derived from Dawn Framing Camera images  

NASA Astrophysics Data System (ADS)

The Dawn Framing Camera (FC) acquired close to 10,000 clear filter images of Vesta with a resolution of about 20 m/pixel during the Low Altitude Mapping Orbit (LAMO) between December 2011 and April 2012. We ortho-rectified these images and produced a global high-resolution uncontrolled mosaic of Vesta. This global mosaic is the baseline for a high-resolution Vesta atlas that consists of 30 tiles mapped at a scale between 1:200,000 and 1:225,180. The nomenclature used in this atlas was proposed by the Dawn team and was approved by the International Astronomical Union (IAU). The whole atlas is available to the public through the Dawn GIS web page [http://dawn_gis.dlr.de/atlas].

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

2013-09-01

175

High Resolution Vesta Survey Atlas derived from Dawn-FC images  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

176

2?-(2-((dimethylamino)methyl)-4?-(2-fluoroalkoxy)-phenylthio)benzenamine Derivatives as Serotonin Transporter Imaging Agents  

PubMed Central

A novel series of ligands with substitutions at the 5-position on phenyl ring A and at the 4?-position on phenyl ring B of 2?-(2-((dimethylamino)methyl)-4?-(2-fluoro- alkoxy)phenylthio)benzenamine (4?-2-fluoroethoxy derivatives, 28–31 and 4?-3-fluoro propoxy derivatives, 40–42) were prepared and tested as serotonin transporter (SERT) imaging agents. The new ligands displayed high binding affinities to SERT (Ki ranging from 0.07 to 1.5 nM). The corresponding 18F labeled compounds, which can be prepared readily, showed excellent brain uptake and retention after iv injection in rats. The hypothalamus region showed high uptake values between 0.74 to 2.2 % dose/g at 120 min post iv injection. Significantly, the hypothalamus to cerebellum ratios (target to non-target ratios) at 120 min were 7.8 and 7.7 for [18F]28 and [18F]40, respectively. The selective uptake and retention in the hypothalamus, which has a high concentration of SERT binding sites, demonstrated that [18F]28 and [18F]40 are promising PET (positron emission computed tomography) imaging agents for mapping SERT binding sites in the brain.

Parhi, Ajit K.; Wang, Julie L.; Oya, Shunichi; Choi, Seok-Rye; Kung, Mei-Ping; Kung, Hank F.

2008-01-01

177

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

178

Edge detection in gated cardiac nuclear medicine images  

Microsoft Academic Search

Mean field annealing using a piecewise linear model was applied to gated cardiac nuclear medicine images as a preprocessing tool for image smoothing and noise reduction. A second derivative operator was then used to extract the edges for ventricle boundary estimation. Combined with the user input initial boundary estimate, the extracted edge information was used to find a minimum cost

Cliff X. Wang; Lon Small; Wesley E. Snyder; Rodney Williams

1994-01-01

179

Feature selection for tree species identification in very high resolution satellite images  

Microsoft Academic Search

The aim of this study was to provide an effective feature selection for tree species classifiers in mixed-species boreal forest, from a very high resolution optical satellite image. The 35 input features were the 5 input spectral bands (multispectral and panchromatic channels), 9 contextual features derived from the panchromatic channel and 21 segment-wise features computed at three segment sizes around

Matthieu Molinier; Heikki Astola

2011-01-01

180

Solar Differential Rotation Derived from H-alpha Full Disk Images by Means of Local Correlation Tracking  

NASA Astrophysics Data System (ADS)

We present the application of Local Correlation Tracking (LCT) techniques to time series of contrast-enhanced H-alpha full disk images taken as part of the synoptic observing program at Big Bear Solar Observatory (BBS0) during the summer of 1998. A typical set of daily H-alpha full disk images consists of 600 to 800 individual frames, taken 30 to 60 s apart, with a 2k x 2k pixel Kodak 4.2 MegaPlus CCD camera at BBSO's Singer telescope. For each pair of successive images, we compute displacement vectors over a 64 x 64 element cartesian grid covering the solar disk. The resulting daily-averaged flow maps show predominantly solar differential rotation and proper motions in active regions. We remap the flow maps to heliographic coordinates and determine a Legendre polynomial expansion of the daily differential rotation profile. We present preliminary findings regarding differential rotation based on different types of features seen in H-alpha, such as quiet-sun fibrils, plages, and dark filaments. We discuss the relation of our differential rotation profiles to profiles derived by other methods and address the question of time variability. The work at BBSO is supported by ONR under grant N00014-97-1-1037, by NSF under grant ATM 97-14796, and by NASA under grant NAG 5-4919. Louis Strous is supported by NASA NAG5-3077 to Stanford University.

Woodard, M. F.; Denker, C.; Strous, L. H.; BBSO Collaboration; LMSAL Collaboration

1999-05-01

181

Modeling Recognition Memory Using the Similarity Structure of Natural Input  

Microsoft Academic Search

Abstract The Natural Input Memory,(NIM) model is a new model for recognition memory,that operates on natural visual input. A biologically-informed perceptual pre-processing method,takes local samples (eye fixations) from a natural image and translates t hese into a feature-vector representation. During recognition, the model compares incoming pre-processed natural input to stored representations. By complementing,the recognition memory,process with a perceptual front-end, the

Joyca P. W. Lacroix; Jaap M. J. Murre; Eric O. Postma; H. Jaap Van Den Herik

2006-01-01

182

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

PubMed

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

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

2013-02-08

183

Reduced state estimator for systems with parametric inputs  

Microsoft Academic Search

A reduced state estimator is derived for systems with bounded parameters as inputs. Optimal filter gains are derived for minimizing the total covariance of the estimation error due to measurement noise and parameter uncertainty. It is shown that these filter gains for a two-state system with a Gaussian parameter satisfy the Kalata relation in steady state. Equations are also derived

PURUSOTTAM MOOKERJEE; FRANK REIFLER

2004-01-01

184

In vivo optical imaging of human lymphoma xenograft using a library-derived peptidomimetic against alpha4beta1 integrin.  

PubMed

Increasing literature suggests that cell adhesion molecule alpha4beta1 integrin plays a pivotal role in autoimmune diseases and cancer development. Noninvasive visualization of alpha4beta1 integrin in vivo will facilitate the understanding of its involvement in disease progression and development of targeted therapies. Due to the lack of high-affinity targeting ligands, molecular imaging of alpha4beta1 integrin is much less explored than that of alphavbeta3 and alphavbeta5 integrins. We have recently reported using the one bead-one compound combinatorial library method to identify a peptidomimetic, LLP2A, that preferentially binds to activated alpha4beta1 integrin. Here, we described the use of LLP2A-Cy5.5 conjugate as an in vivo optical imaging probe in a human lymphoma xenograft model. This univalent LLP2A-Cy5.5 conjugate retained the binding activity and specificity to alpha4beta1 integrin as shown by cell binding assays using alpha4beta1-positive Molt-4 T-leukemia cells. The subcutaneous Molt-4 tumor was clearly visualized from 1 to 24 h after tail vein injection of the conjugate. Direct imaging and confocal microscopic examination of excised tumors and organs confirmed the accumulation of LLP2A in tumors and revealed very little or no uptake in normal organs except for lymph nodes. Kidney uptake was high when the whole organ was scanned but it was negative when examined microscopically, suggesting that LLP2A bound to the renal tubules loosely. Tumor uptake of LLP2A-Cy5.5 conjugate was blocked by excess unlabeled LLP2A. This study showed that the combinatorial chemical library-derived peptidomimetic LLP2A can be easily developed into an optical imaging probe for noninvasively monitoring of activated alpha4beta1 integrin in vivo. PMID:18245670

Peng, Li; Liu, Ruiwu; Andrei, Mirela; Xiao, Wenwu; Lam, Kit S

2008-02-01

185

Input transformations for Lagrange's equations of space vehicle motion  

Microsoft Academic Search

This paper outlines the general framework for transforming the input variables of Lagrange's equations. The theory is presented from the viewpoint of preserving the virtual work. A transformation is derived that transforms the input forces and torques of a six-degree of freedom space vehicle into realizable forces and torques. Analytical analysis and simulations are performed to demonstrate the results.

Douglas R. Isenberg; Y. P. Kakad

2009-01-01

186

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

187

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

PubMed Central

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

Tatrai, Erika; Ranganathan, Sudarshan; Ferencz, Maria; DeBuc, Delia Cabrera; Somfai, Gabor Mark

2011-01-01

188

Controlling for premorbid brain size in imaging studies: T1-derived cranium scaling factor vs. T2-derived intracranial vault volume  

Microsoft Academic Search

Intracranial vault (ICV) volume, obtained from T2-weighted magnetic resonance imaging (MRI), is generally used to estimate premorbid brain size in imaging studies. T1-weighted sequences lack the signal characteristics for ICV measurements [they have poor contrast at the outer boundary of sulcal cranium scaling factor (CSF)] but are valuable in imaging studies due to their excellent gray vs. white matter contrast.

George Fein; Victoria Di Sclafani; Colin Taylor; Kirk Moon; Jerome Barakos; Hoang Tran; Bennett Landman; Robert Shumway

2004-01-01

189

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.

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

2010-01-01

190

Synthesis and evaluation of a novel 68Ga-labeled DOTA-benzamide derivative for malignant melanoma imaging.  

PubMed

Malignant melanoma displays a highly aggressive metastasis. Thus, early diagnosis of malignant melanoma is important for patient survival. We designed and synthesized a novel (68)Ga-labeled benzamide derivative that specifically binds to melanoma as demonstrated by its ability to bind to melanin. (68)Ga-SCN-DOTA-PCA was synthesized with a radiochemical yield of ~80% and a radiochemical purity of >97% by analytical HPLC. The in vitro binding of (68)Ga-SCN-DOTA-PCA to melanin and its cellular uptake demonstrated the selective uptake in melanin. In addition, the biodistribution and micro-PET imaging of (68)Ga-SCN-DOTA-PCA in B16F10 tumor models showed the specific accumulation in melanoma. These results suggest that (68)Ga-SCN-DOTA-PCA would be a promising agent for melanoma diagnosis. PMID:22796183

Kim, Hee-Jung; Kim, Dong-Yeon; Park, Jeong-Hoon; Yang, Seung-Dae; Hur, Min-Goo; Min, Jung-Joon; Yu, Kook-Hyun

2012-06-19

191

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

192

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

NASA Astrophysics Data System (ADS)

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

Lukianova, R.; Kozlovsky, A.

2013-01-01

193

Deriving a blood-mimicking fluid for particle image velocimetry in Sylgard-184 vascular models.  

PubMed

A new blood-mimicking fluid (BMF) has been developed for particle image velocimetry (PIV), which enables flow studies in vascular models (phantoms). A major difficulty in PIV that affects measurement accuracy is the refraction and distortion of light passing through the interface between the model and the fluid, due to the difference in refractive index (n) between the two materials. The problem can be eliminated by using a fluid with a refractive index matching that of the model. Such fluids are not commonly available, especially for vascular research where the fluid should also have a viscosity similar to human blood. In this work, a blood-mimicking fluid, composed of water (47.38% by weight), glycerol (36.94% by weight) and sodium iodide salt (15.68% by weight), was developed for compatibility with our silicone (Sylgard 184; n = 1.414) phantoms. The fluid exhibits a dynamic viscosity of 4.31+/-0.03 cP which lies within the range of human blood viscosity (4.4+/-0.6 cP). Both refractive index and viscosity were attained at 22.2+/-0.2 degrees C, which is a feasible room temperature, thus eliminating the need for a temperature-control system. The fluid will be used to study hemodynamics in vascular flow models fabricated from Sylgard 184. PMID:19964526

Yousif, Majid Y; Holdsworth, David W; Poepping, Tamie L

2009-01-01

194

[Comparison of diffusion tensor imaging-derived fractional anisotropy in multiple centers for identical human subjects].  

PubMed

The fractional anisotropy (FA) is calculated by using diffusion tensor imaging (DTI) with multiple motion probing gradients (MPG). While FA has become a widely used tool to detect moderate changes in water diffusion in brain tissue, the measured value is sensitive to scan parameters (e.g. MPG-direction, signal to noise ratio, etc.). Therefore, it is paramount to address the reproducibility of DTI measurements among multiple centers. The purpose of this study was to assess the inter-center variability of FA. We studied five healthy volunteers who underwent DTI brain scanning three times at three different centers (I-III), each with a 1.5 T scanner having a different MPG-schema. Then, we compared the FA and eigenvalue from the three centers measured in seven brain regions: splenium of corpus callosum (CCs), genu of corpus callosum (CCg), putamen, posterior limb of internal capsule, cerebral peduncle, optic radiation, and middle cerebellar peduncle. At the CCs and CCg, there was a statistical difference (p<0.05) between center Iand center IIfor the same MPG-directions. Furthermore, at CCs and CCg, there was a statistical difference (p<0.05) between center II and center III for different MPG-directions. Conversely, no statistical differences were found between center I and center III for the different MPG-directions for all regions. These results indicate that the FA value was affected by the MPG-schema as well as by the MPG-directions. PMID:23001272

Saotome, Kousaku; Ishimori, Yoshiyuki; Isobe, Tomonori; Satou, Eisuke; Shinoda, Kazuya; Ookubo, Jun; Hirano, Yuuji; Oosuka, Satoru; Matsushita, Akira; Miyamoto, Katsumi; Sankai, Yoshiyuki

2012-01-01

195

Synthesis and biological evaluation of 18F-labled 2-phenylindole derivatives as PET imaging probes for ?-amyloid plaques.  

PubMed

A novel series of fluorinated 2-phenylindole derivatives were synthesized and evaluated as ?-amyloid imaging probes for PET. The in vitro inhibition assay demonstrated that their binding affinities for A?(1-42) aggregates ranged from 28.4 to 1097.8 nM. One ligand was labeled with (18)F ([(18)F]1a) for its high affinity (K(i)=28.4 nM), which was also confirmed by in vitro autoradiography experiments on brain sections of transgenic mouse (C57BL6, APPswe/PSEN1, 11 months old, male). In vivo biodistribution experiments in normal mice showed that this radiotracer displayed high initial uptake (5.82±0.51% ID/g at 2 min) into and moderate washout (2.77±0.31% ID/g at 60 min) from the brain. [(18)F]1a could be developed as a promising new PET imaging probe for A? plaques although necessary modifications are still needed. PMID:23673220

Fu, Hualong; Yu, Lihai; Cui, Mengchao; Zhang, Jinming; Zhang, Xiaojun; Li, Zijing; Wang, Xuedan; Jia, Jianhua; Yang, Yanping; Yu, Pingrong; Jia, Hongmei; Liu, Boli

2013-04-24

196

Large two-photon absorption of terpyridine-based quadrupolar derivatives: towards their applications in optical limiting and biological imaging.  

PubMed

Developing organic chromophores with large two-photon absorption (TPA) in both organic solvents and aqueous media is crucial owing to their applications in solid-state photonic devices and biological imaging. Herein, a series of novel terpyridine-based quadrupolar derivatives have been synthesized. The influences of electron-donating group, type of conjugated bridge, as well as solvent polarity on the molecular TPA properties have been investigated in detail. In contrast to the case in organic solvents, bis(thienyl)-benzothiadiazole as a rigid conjugated bridge will completely quench molecular two-photon emission in aqueous media. However, the combination of alkylcarbazole as the donor and bis(styryl)benzene as a conjugation bridge can enlarge molecular TPA cross-sections in both organic solvent and aqueous media. The reasonable two-photon emission brightness for the organic nanoparticles of chromophores 3-5 in the aqueous media, prepared by the reprecipitation method, enables them to be used as probes for in vivo biological imaging. PMID:23281197

He, Tingchao; Lim, Zheng Bang; Ma, Lin; Li, Hairong; Rajwar, Deepa; Ying, Yongjun; Di, Ziyun; Grimsdale, Andrew C; Sun, Handong

2012-12-28

197

Theranostic effect of serial manganese-enhanced magnetic resonance imaging of human embryonic stem cell derived teratoma.  

PubMed

Although human embryonic stem cell (hESC) hold therapeutic potential, teratoma formation has deterred clinical translation. Manganese (Mn(2+)) enters metabolically active cells through voltage-gated calcium channels and subsequently, induces T(1) shortening. We hypothesized that serial manganese-enhanced MRI would have theranostic effect to assess hESC survival, teratoma formation, and hESC-derived teratoma reduction through intracellular accumulation of Mn(2+). Firefly luciferase transduced hESCs (hESC-Lucs) were transplanted into severe combined immunodeficient mouse hindlimbs to form teratoma. The chemotherapy group was injected with MnCl(2) intraperitoneally three times a week. The control group was given MnCl(2) only prior to manganese-enhanced MRI. Longitudinal evaluation by manganese-enhanced MRI and bioluminescence imaging was performed. The chemotherapy group showed significant reduction in the teratoma volume and luciferase activity at weeks 6 and 8. Histology revealed increased proportion of dead cells and caspase 3 positive cells in the chemotherapy group. Systemic administration of MnCl(2) enabled simultaneous monitoring and elimination of hESC-derived teratoma cells by higher intracellular accumulation of Mn(2+). PMID:22190225

Chung, Jaehoon; Dash, Rajesh; Kee, Kehkooi; Barral, Joëlle K; Kosuge, Hisanori; Robbins, Robert C; Nishimura, Dwight; Reijo-Pera, Renee A; Yang, Phillip C

2011-12-21

198

Theranostic effect of serial manganese-enhanced magnetic resonance imaging of human embryonic stem cell derived teratoma  

PubMed Central

Although hESCs hold therapeutic potential, teratoma formation has deterred clinical translation. Manganese (Mn2+) enters metabolically active cells through voltage-gated calcium channels and, subsequently, induces T1 shortening. We hypothesized that serial MEMRI would have theranostic effect to assess hESC survival, teratoma formation, and hESC-derived teratoma reduction through intracellular accumulation of Mn2+. Firefly luciferase transduced hESCs (hESC-Lucs) were transplanted into SCID mouse hindlimbs to form teratoma. The chemotherapy group was injected with MnCl2 IP three times a week. The control group was given MnCl2 only prior to MEMRI. Longitudinal evaluation by MEMRI and bioluminescence imaging (BLI) was performed. The chemotherapy group showed significant reduction in the teratoma volume and luciferase activity at weeks 6 and 8. Histology revealed increased proportion of dead cells and caspase 3 positive cells in the chemotherapy group. Systemic administration of MnCl2 enabled simultaneous monitoring and elimination of hESC-derived teratoma cells by higher intracellular accumulation of Mn2+.

Chung, Jaehoon; Dash, Rajesh; Kee, Kehkooi; Barral, Joelle K.; Kosuge, Hisanori; Robbins, Robert C.; Nishimura, Dwight; Reijo-Pera, Renee A.; Yang, Phillip C.

2011-01-01

199

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

2013-01-28

200

Fire temperature and fractional area derivations over the world trade center disaster site from imaging spectometer measurements  

NASA Astrophysics Data System (ADS)

As part of the World Trade Center disaster response, the NASA Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) was flown over the site on the 16t h and 18t h of September 2001. AVIRIS measures the solar reflected spectrum from 370 to 2500-nm at 10-nm sampling. For this flight the data were acquired at 1.5-m spatial sampling with image coverage of the entire disaster site. AVIRIS measurements are spectrally, radiometrically, spatially calibrated in the laboratory and validated in flight. Rapid examination of the World Trade Center AVIRIS data in the 2300 nm spectral region showed numerous high radiance targets indicative of burning fires. A new spectroscopic algorithm was implem n ted to simultaneously solve for thee temperature and fractional area of the fires. This algorithm uses the Planck function in conjunction with the full spectral shape measured by AVIRIS to determine the temperature and fractional area of the fire. This spectral algorithm overcomes the ambiguity between temperature and area that exists in single -spectral-b a n d temperature estimation methods. With these AVIRIS data set and new algorithm, 8 hot spot zones were identified in the September 16t h data with temperatures ranging from 700 to 1019 - K and fractional areas from 1.1 to 18-%. Analysis of the data set acquired on Septemb e r 18t h showed 7 of the hot spot zones still present with temperatures ranging from 471 to 952-K and fractional areas from 0.5 to 36-%. These imaging spectrometer derived physical parameters of fire temperature and fractional-area were found useful to the personnel making decisions on the ground. The complete set measurements, analyses, and results of this effort are reported in this paper.

Green, R.; Clark, R.; Boardman, J.

201

Radioiodinated styrylbenzene derivatives as potential SPECT imaging agents for amyloid plaque detection in Alzheimer's disease.  

PubMed

Development of probes for beta-amyloid (A beta) plaques, a critical factor associated with Alzheimer's disease (AD), provides important tools for studying their role in AD. Previously, we reported [125I]IMSB and [125I]ISB as excellent probes for A beta plaque labeling. Despite their exquisite in vitro binding characteristics, low brain uptakes (likely due to two ionizable carboxylic acid groups) limited their potential as in vivo imaging agents. To improve brain penetration, we have successfully prepared a neutral radioiodinated probe [125I]3. The improved probe displayed good binding affinity for A beta aggregates (Ki = 2.0 +/- 0.2 using A beta40 aggregates). In addition, the brominated counterpart displayed fluorescent-staining properties of A beta plaques in postmortem AD brain sections similar to BSB, a fluoroscent probe reported previously. [125I]3 gave excellent plaque labeling by film autoradiography of AD brain sections. Unlike [125I]IMSB (which preferentially detects A beta40 plaques), the improved radioioinated probe, [125I]3, can readily detect plaques containing aggregates of both A beta40 and A beta42. The initial brain uptake of [125I]3 in normal mice at 2 min p.i. was moderate (0.18% ID) and displayed a very slow washout from the brain (0.11%.ID at 4 h p.i). Taken together, these data suggest that [125I]3 is useful for in vitro plaque detection, it may not be suitable for in vivo monitoring of A beta progression and deposition. PMID:12212796

Kung, Mei-Ping; Hou, Catherine; Zhuang, Zhi-Ping; Skovronsky, Daniel M; Zhang, Bin; Gur, Tamar L; Trojanowski, John Q; Lee, Virginia M Y; Kung, Hank F

202

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

203

Synthesis and in vitro biological evaluation of carbon-11-labeled quinoline derivatives as new candidate PET radioligands for cannabinoid CB2 receptor imaging  

Microsoft Academic Search

Cannabinoids have been recently proposed as a new family of potential antitumor agents, and cannabinoid receptor 2 (CB2) is believed to be over-expressed in tumor cells. This study was designed to develop new radioligands for imaging of CB2 receptor in cancer using biomedical imaging technique positron emission tomography (PET). Carbon-11-labeled 2-oxoquinoline and 2-chloroquinoline derivatives, [11C]6a–d and [11C]9a–d, were prepared by

Mingzhang Gao; Min Wang; Kathy D. Miller; Gary D. Hutchins; Qi-Huang Zheng

2010-01-01

204

Input estimation for nonlinear systems  

Microsoft Academic Search

A novel input estimation inverse methodology of determining the time-varying exciting forces, named as the input, in a nonlinear system is presented. These forces are estimated from the measured dynamic response data of a nonlinear system using the approach. The algorithm includes the extended Kalman filter (KF) with a recursive estimator. The extended KF generates the residual innovation sequences. The

Dong-Cherng Lin

2010-01-01

205

Magnetic resonance imaging tracking of human adipose derived stromal cells within three-dimensional scaffolds for bone tissue engineering.  

PubMed

For bone tissue engineering, human Adipose Derived Stem Cells (hADSCs) are proposed to be associated with a scaffold for promoting bone regeneration. After implantation, cellularised scaffolds require a non-invasive method for monitoring their fate in vivo. The purpose of this study was to use Magnetic Resonance Imaging (MRI)-based tracking of these cells, labelled with magnetic agents for in vivo longitudinal assessment. hADSCs were isolated from adipose tissue and labelled with USPIO-rhodamine (Ultrasmall SuperParamagnetic Iron Oxide). USPIO internalisation, absence of toxicity towards hADSCs, and osteogenic differentiation of the labelled cells were evaluated in standard culture conditions. Labelled cells were then seeded within a 3D porous polysaccharide-based scaffold and imaged in vitro using fluorescence microscopy and MRI. Cellularised scaffolds were implanted subcutaneously in nude mice and MRI analyses were performed from 1 to 28 d after implantation. In vitro, no effect of USPIO labelling on cell viability and osteogenic differentiation was found. USPIO were efficiently internalised by hADSCs and generated a high T2* contrast. In vivo MRI revealed that hADSCs remain detectable until 28 d after implantation and could migrate from the scaffold and colonise the area around it. These data suggested that this scaffold might behave as a cell carrier capable of both holding a cell fraction and delivering cells to the site of implantation. In addition, the present findings evidenced that MRI is a reliable technique to validate cell-seeding procedures in 3D porous scaffolds, and to assess the fate of hADSCs transplanted in vivo. PMID:21484704

Lalande, C; Miraux, S; Derkaoui, S M; Mornet, S; Bareille, R; Fricain, J C; Franconi, J M; Le Visage, C; Letourneur, D; Amédée, J; Bouzier-Sore, A K

2011-04-11

206

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

207

Computer-Aided Diagnosis in Breast MRI: Do Adjunct Features Derived from T 2-weighted Images Improve Classification of Breast Masses?  

NASA Astrophysics Data System (ADS)

In the field of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) of breast cancer, current research efforts in computer-aided diagnosis (CADx) are mainly focused on the temporal series of T 1-weighted images acquired during uptake of a contrast agent, processing morphological and kinetic information. Although static T 2-weighted images are usually part of DCE-MRI protocols, they are seldom used in CADx systems. The aim of this work was to evaluate to what extent T 2-weighted images provide complementary information to a CADx system, improving its performance for the task of discriminating benign breast masses from life-threatening carcinomas. In a preliminary study considering 64 masses, inclusion of lesion features derived from T 2-weighted images increased the classification performance from A z =0.94 to A z =0.99.

van Aalst, Willem; Twellmann, Thorsten; Buurman, Hans; Gerritsen, Frans A.; Ter Haar Romeny, Bart M.

208

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

209

Reference ranges of ductus arteriosus derived by cardio-spatiotemporal image correlation from 14 to 40 weeks of gestation.  

PubMed

Objective: To construct reference ranges of fetal ductus arteriosus (DA) derived by volume datasets of cardio-spatiotemporal image correlation (cardio-STIC). Methods: Cardio-STIC volume datasets were acquired from low-risk singleton pregnancies with a reliable gestational age from 14 to 40 weeks. In offline analysis with 4D View version 9, fetal DA was measured in the transverse ductal arch view with orthogonal control in the multiplanar view. The reference ranges of the DA and Z-score equation were constructed against gestational weeks and biparietal diameter (BPD) as independent variables. Results: A total of satisfactory 606 volumes were analyzed. The reference ranges for predicting means and SDs of fetal DA were constructed based on the best-fit regression model. Mean DA (mm) was best predicted by linear model as a function of GA (weeks) and BPD (cm) as follows: Predicted DA diameter (cm) = -0.051 + 0.014 × GA (weeks) (r = 0.84) and Predicted DA diameter (cm) = -0.015 + 0.053 × BPD (cm) (r = 0.83). Models for Z-score calculation and centile charts for predicting fetal DA were also provided. Conclusion: Reference ranges of the fetal DA and Z-score model are provided. These may serve as a useful tool in the assessment of fetal DA, especially in fetal cardiac anomalies or in monitoring fetuses exposed to maternal indomethacin. PMID:23635389

Traisrisilp, Kuntharee; Tongprasert, Fuanglada; Srisupundit, Kasemsri; Luewan, Suchaya; Tongsong, Theera

2013-04-30

210

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

PubMed

INTRODUCTION: No comparative study of adipose-derived stem cells (ADSCs) and bone marrow mesenchymal stem cells (BMSCs) by using superparamagnetic iron oxide nanoparticles (SPIOs)-labeling and magnetic resonance imaging (MRI) has been performed. METHODS: We studied the biological activity and MRI of ADSCs by labeling them with SPIOs and comparing them with BMSCs. After incubating the cells in culture medium with different levels of SPIOs (control group: 0 ?g/ml; Groups 1 to 3: 25, 50, and 100 ?g/ml) for 24 hours, we compared ADSCs with BMSCs in terms of intracellular iron content, labeling efficiency, and cell viability. Stem cells in the culture medium containing 50 ?g/ml SPIOs were induced into osteoblasts and fat cells. Adipogenic and osteogenic differentiation potentials were compared. R2* values of MRI in vitro were compared. RESULTS: The results showed that labeling efficiency was highest in Group 2. Intracellular iron content and R2* values increased with increasing concentrations of SPIOs, whereas cell viability decreased with increasing concentrations of SPIOs, and adipogenic and osteogenic differentiation potentials decreased. However, we found no significant difference between the two kinds of cells for any of these indexes. CONCLUSIONS: ADSCs can be labeled and traced as easily as BMSCs in vitro. Given their abundance and higher proliferative capacity, as was previously shown, ADSCs may be better suited to stem cell therapy than are BMSCs. PMID:23618360

Fan, Jingjing; Tan, Yanbin; Jie, Liyong; Wu, Xinying; Yu, Risheng; Zhang, Minming

2013-04-23

211

Opportunities to Refine Regional Crop Modeling Using Current and Simulated Future NASA Data Inputs in RPC Framework  

NASA Astrophysics Data System (ADS)

The Sinclair soybean prediction model requires daily meteorological data inputs of minimum and maximum temperature, solar radiation, precipitation along with data such as planting date and day length based on latitude. The model estimates daily LAI (Leaf Area Index) from the input variables to simulate yield. The Sinclair model has been used operationally by USDA/FAS PECAD to provide soybean yield forecasts before harvest. Various approaches to deriving model input parameters from remote sensing datasets have been suggested to improve model efficiency and to reduce the time and labor requirements for regional yield predictions. This research will evaluate the use of current and simulated future NASA data sources as well as model products as proxy input parameters for regional yield predication. The effort will employ NASA data streams to determine whether the current NASA datasets from MODIS (Moderate Resolution Imaging Spectroradiometer) and simulated future products from VIIRS (Visible Infrared Imager / Radiometer Suite) as well as meteorological data from NASA `LDAS' (Land Data Assimilation System) can be used as surrogate input variables to replace the current method of data input in the model so as to improve the technical methodologies of regional yield prediction using remote sensing data streams. The area of interest is in Argentina, South America, one of the largest soybean growing nations. MODIS datasets and simulated VIIRS datasets from MODIS will be compared to rapidly prototype soybean production estimation and to benchmark the ability of NASA data-streams to provide vegetation vigor as an input to the soybean prediction model to provide effective technological solutions in an RPC framework for USDA/FAS PECAD's operational efficiency.

Mali, P.; O'Hara, C. G.; Shrestha, B.; Sinclair, T.; Toll, D.

2006-12-01

212

Use of a beta microprobe system to measure arterial input function in PET via an arteriovenous shunt in rats  

PubMed Central

Background Kinetic modeling of physiological function using imaging techniques requires the accurate measurement of the time-activity curve of the tracer in plasma, known as the arterial input function (IF). The measurement of IF can be achieved through manual blood sampling, the use of small counting systems such as beta microprobes, or by derivation from PET images. Previous studies using beta microprobe systems to continuously measure IF have suffered from high background counts. Methods In the present study, a light-insensitive beta microprobe with a temporal resolution of up to 1 s was used in combination with a pump-driven femoral arteriovenous shunt to measure IF in rats. The shunt apparatus was designed such that the placement of the beta microprobe was highly reproducible. The probe-derived IF was compared to that obtained from manual sampling at 5-s intervals and IF derived from a left ventricle VOI in a dynamic PET image of the heart. Results Probe-derived IFs were very well matched to that obtained by "gold standard" manual blood sampling, but with an increased temporal resolution of up to 1 s. The area under the curve (AUC) ratio between probe- and manually derived IFs was 1.07 ± 0.05 with a coefficient of variation of 0.04. However, image-derived IFs were significantly underestimated compared to the manually sampled IFs, with an AUC ratio of 0.76 ± 0.24 with a coefficient of variation of 0.32. Conclusions IF derived from the beta microprobe accurately represented the IF as measured by blood sampling, was reproducible, and was more accurate than an image-derived technique. The use of the shunt removed problems of tissue-background activity, and the use of a light-tight probe with minimal gamma sensitivity refined the system. The probe/shunt apparatus can be used in both microprobe and PET studies.

2011-01-01

213

Touch-sensing input devices  

Microsoft Academic Search

We can touch things, and our senses tell us when our hands aretouching something. But most computer input devices cannot detectwhen the user touches or releases the device or some portion of thedevice. Thus, adding touch sensors to input devices offers manypossibilities for novel interaction techniques. We demonstrate theTouchTrackball and the Scrolling TouchMouse, which use unobtrusivecapacitance sensors to detect contact

Ken Hinckley; Mike Sinclair

1999-01-01

214

Advective surface velocities derived from sequential images for rotational flow field: Limitations and applications of maximum cross-correlation method with rotational registration  

NASA Astrophysics Data System (ADS)

An objective technique is developed to calculate advective surface velocities from sequential images. A pattern matching method is used with the identification of maximum cross correlation (MCC) between a template window in the first image and search areas in the second image. We examined the limitations of the MCC method in two cases: (1) eddy size (LE) much smaller than the radius of deformation (LD), and (2) LE?LD. In the first case an eddy is regarded as a particle. Maximum detectable time period is estimated to be about 1 day. For the second case we developed the MCC method to detect a rotational motion. We compared velocity fields derived from the method with a real velocity field in a numerical analysis of tracer and quasi-geostrophic eddy fields. The optimal template size is about the eddy diameter which spans between the maximum velocity points. We also applied the MCC method to infrared images in the Kuroshio-Oyashio confluence zone.

Kamachi, M.

1989-12-01

215

Baseline tissue Doppler imaging-derived echocardiographic parameters and left ventricle reverse remodelling following cardiac resynchronization therapy introduction  

PubMed Central

Introduction The aim of the study was to assess the relation of baseline mechanical dyssynchrony with the left ventricular end-systolic volume (LVESV) decrease following cardiac resynchronization (CRT) therapy introduction. Material and methods Sixty consecutive patients (aged 66.3 ± 8.7 years; 57 men) with chronic heart failure (71.7% of ischaemic and 28.3% of non-ischaemic origin) and current indications for CRT were assessed before and 3 months after biventricular heart stimulator implantation. Longitudinal movements of twelve segments of the left ventricle (LV) (6 basal and 6 midlevel) and two segments of the right ventricle (RV) were analysed using tissue Doppler imaging (TDI) techniques with time from onset of Q wave in ECG to peak systolic velocity in colour-coded TDI (TTDI), time to peak strain (Tstrain) and time to peak strain rate (Tstrain rate). Minimal and maximal time differences within LV and between LV and RV walls were calculated. Results In the study group LVEF and 6-min walk test distance increased, while NYHA class, NT-proBNP level, left ventricular end-diastolic volume and LVESV decreased. Significant correlations between the magnitude of LVESV reduction with maximal time differences between Tstrain of 12 LV segments (r=0.34, p = 0.017) and time differences between TTDI basal LV-RV segments (r = –0.29, p=0.041) were found. Conclusions Only a few TDI-derived parameters such as maximal time differences between Tstrain of 12 LV segments and TTDI difference of LV-RV basal segments can be useful to predict the magnitude of left ventricle reverse remodelling after CRT introduction.

Wilinski, Jerzy; Czarnecka, Danuta; Wojciechowska, Wiktoria; Kloch-Badelek, Malgorzata; Jastrzebski, Marek; Bacior, Bogumila; Sondej, Tomasz; Kusiak, Aleksander

2011-01-01

216

On the asymptotic input-output weight distributions and thresholds of convolutionaland turbo-like encoders  

Microsoft Academic Search

We present a general method for computing the asymptotic input-output weight distribution of convolutional encoders. In some instances, one can derive explicit analytic expressions. In general, though, to determine the growth rate of the input-output weight distribution for a particular normalized input weight ? and output weight ?, a system of polynomial equations has to be solved. This method is

Igal Sason; Ì. Emre Telatar; Rüdiger L. Urbanke

2002-01-01

217

Input Type and Parameter Resetting: Is Naturalistic Input Necessary?  

ERIC Educational Resources Information Center

|It has been argued that extended exposure to naturalistic input provides L2 learners with more of an opportunity to converge of target morphosyntactic competence as compared to classroom-only environments, given that the former provide more positive evidence of less salient linguistic properties than the latter (e.g., Isabelli 2004). Implicitly,…

Rothman, Jason; Iverson, Michael

2007-01-01

218

Spatiotemporal variations of snowmelt in Antarctica derived from satellite scanning multichannel microwave radiometer and Special Sensor Microwave Imager data (1978-2004)  

Microsoft Academic Search

We derived the extent, onset date, end date, and duration of snowmelt in Antarctica from 1978 to 2004 using satellite passive microwave scanning multichannel microwave radiometer (SMMR) and Special Sensor Microwave Imager (SSM\\/I) data. A wavelet-transform-based method was developed to determine and characterize melt occurrences. About 9-12% of the Antarctic surface experiences melt annually. This is more than twice the

Hongxing Liu; Lei Wang; Kenneth C. Jezek

2006-01-01

219

Spatiotemporal variations of snowmelt in Antarctica derived from satellite scanning multichannel microwave radiometer and Special Sensor Microwave Imager data (1978–2004)  

Microsoft Academic Search

We derived the extent, onset date, end date, and duration of snowmelt in Antarctica from 1978 to 2004 using satellite passive microwave scanning multichannel microwave radiometer (SMMR) and Special Sensor Microwave Imager (SSM\\/I) data. A wavelet-transform-based method was developed to determine and characterize melt occurrences. About 9–12% of the Antarctic surface experiences melt annually. This is more than twice the

Hongxing Liu; Lei Wang; Kenneth C. Jezek

2006-01-01

220

Efficient radiosynthesis of carbon-11 labelled uncharged Thioflavin T derivatives using [ 11C]methyl triflate for ? -amyloid imaging in Alzheimer's Disease with PET  

Microsoft Academic Search

The synthesis of carbon-11 amino function labelled uncharged Thioflavin T derivatives is known to be performed by reaction of the demethyl-precursors with [11C]methyl iodide but the labelling yields are only mediocre. The use of [11C]methyl triflate improved the radiochemical yield of three potential ?-amyloid imaging PET-radiotracers significantly. Performance of the labelling reaction by reacting the corresponding precursor molecules with [11C]methyl

C. Solbach; M. Uebele; G. Reischl; H.-J. Machulla

2005-01-01

221

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

222

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

NASA Astrophysics Data System (ADS)

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

Bahmani, Baharak; Bacon, Danielle; Anvari, Bahman

2013-07-01

223

Image restoration using online photo collections  

Microsoft Academic Search

We present an image restoration method that leverages a large database of images gathered from the web. Given an input image, we execute an efficient visual search to find the closest images in the database; these images define the input's visual context. We use the visual context as an image-specific prior and show its value in a variety of image

Kevin Dale; Micah K. Johnson; Kalyan Sunkavalli; Wojciech Matusik; Hanspeter Pfister

2009-01-01

224

7 CFR 3430.607 - Stakeholder input.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Stakeholder input. 3430.607 Section 3430...Rancher Development Program § 3430.607 Stakeholder input. CSREES shall seek and obtain stakeholder input through a variety of forums...

2010-01-01

225

7 CFR 3430.907 - Stakeholder input.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Stakeholder input. 3430.907 Section 3430...Competitive Grants Program § 3430.907 Stakeholder input. CSREES shall seek and obtain stakeholder input through a variety of forums...

2010-01-01

226

SAM: an improved input device  

Microsoft Academic Search

SAM allows people to communicate by sending Morse code with a single switch. Unlike most Morse code input devices, SAM allows extreme latitude in the timing of dots and dashes. This makes it usable by people who have trouble mastering the precise timing of conventional Morse code. SAM is portable and inexpensive-it costs about $50 to build and runs on

L. T. Hauck

1992-01-01

227

INCA (Input catalog) Data Base.  

National Technical Information Service (NTIS)

The construction and the contents of the input catalog (INCA) data base are presented. It contains the compiled data on all stars processed by the INCA Consortium, which are about 215,000. The specific software developed for handling the data base, is out...

A. Gomez D. Morin F. Arenou

1989-01-01

228

Lab Inputs for Common Micros.  

ERIC Educational Resources Information Center

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

Tinker, Robert

1984-01-01

229

Long-term live-cell imaging of mammalian preimplantation development and derivation process of pluripotent stem cells from the embryos.  

PubMed

Mammalian fertilization is a process in which two highly specialized haploid gametes unite and endow totipotency to the resulting diploid zygote. This is followed by cell proliferation and the onset of differentiation during the brief period leading up to implantation. In these processes, a number of cellular components and structures are regulated spatially and temporally, as seen in repeated cell division, cell cycle progression, and epigenetic reprogramming. In mammals, the numbers of oocytes and embryos that can be collected are very limited. Therefore, analyses of molecular mechanisms are hampered because of difficulties in conducting biochemical analyses on such limited material. Furthermore, immunostaining methods require cell fixation and are insufficient for understanding ontogeny, because the processes observed in fertilization and early embryonic development progress in time-dependent manners and each phenomenon is connected with others by cause-and-effect relationships. Consequently, it is important to develop an experimental system that enables molecular imaging without affecting embryonic development. To achieve the above advantages, especially retrospective and prospective analyses, we have established a live-cell imaging system that enables observations under minimally invasive conditions. Using this approach, we have succeeded in visualizing and predicting the developmental potential of embryos after various perturbations. We also succeeded in imaging embryonic stem (ES) cell derivation in natural conditions. In this review, we describe a brief history of embryonic imaging and detailed protocols. We also discuss promising aspects of imaging in the fields of developmental and stem cell biology. PMID:23495974

Yamagata, Kazuo; Ueda, Jun

2013-03-18

230

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

231

Visual Input Driving Human Smooth-Pursuit Eye Movements.  

National Technical Information Service (NTIS)

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

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

1996-01-01

232

Mathematical image analysis based cell reprogramming with applications for epigenetic and non-epigenetic base induced pluripotent stem cell derivation  

US Patent & Trademark Office Database

Mathematical and statistical image analysis methods and systems are applied to enhance and refine the process of reprogramming cells, for example, to modify cells from patients into custom-matched stem cells.

Mangoubi; Rami (Newton, MA); Sammak; Paul J. (Pittsburgh, PA); Desai; Mukund (Needham, MA); Lowry; Nathan (Lexington, MA)

2013-08-20

233

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

234

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

Microsoft Academic Search

We present infrared interferometric imaging of the S-type Mira star chi Cygni. The object was observed at four different epochs in 2005-2006 with the Infrared-Optical Telescope Array optical interferometer (H band). Images show up to 40% variation in the stellar diameter, as well as significant changes in the limb darkening and stellar inhomogeneities. Model fitting gave precise time-dependent values of

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

2009-01-01

235

Comparison of Simulated and Measured Synthetic Aperture Radar Image Spectra with Buoy-Derived Ocean Wave Spectra During the Shuttle Imaging Radar B Mission  

Microsoft Academic Search

During the SIR-B mission over the North Sea, two successful synthetic aperture radar (SAR) data takes with simultaneous buoy measurements of ocean wave spectra have been obtained on October 6 and 8, 1984. On October 6, the SAR imaging of ocean waves was predicted as strongly nonlinear and on October 8 as almost linear. The SIR-B experiment confirmed the theoretical

Werner Alpers; Claus Bruening; Karl Richter

1986-01-01

236

Power spectra of the natural input to the visual system.  

PubMed

The efficient coding hypothesis posits that sensory systems are adapted to the regularities of their signal input so as to reduce redundancy in the resulting representations. It is therefore important to characterize the regularities of natural signals to gain insight into the processing of natural stimuli. While measurements of statistical regularity in vision have focused on photographic images of natural environments it has been much less investigated, how the specific imaging process embodied by the organism's eye induces statistical dependencies on the natural input to the visual system. This has allowed using the convenient assumption that natural image data are homogeneous across the visual field. Here we give up on this assumption and show how the imaging process in a human model eye influences the local statistics of the natural input to the visual system across the entire visual field. Artificial scenes with three-dimensional edge elements were generated and the influence of the imaging projection onto the back of a spherical model eye were quantified. These distributions show a strong radial influence of the imaging process on the resulting edge statistics with increasing eccentricity from the model fovea. This influence is further quantified through computation of the second order intensity statistics as a function of eccentricity from the center of projection using samples from the dead leaves image model. Using data from a naturalistic virtual environment, which allows generation of correctly projected images onto the model eye across the entire field of view, we quantified the second order dependencies as function of the position in the visual field using a new generalized parameterization of the power spectra. Finally, we compared this analysis with a commonly used natural image database, the van Hateren database, and show good agreement within the small field of view available in these photographic images. We conclude by providing a detailed quantitative analysis of the second order statistical dependencies of the natural input to the visual system across the visual field and demonstrating the importance of considering the influence of the sensory system on the statistical regularities of the input to the visual system. PMID:23458676

Pamplona, D; Triesch, J; Rothkopf, C A

2013-03-01

237

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

NASA Astrophysics Data System (ADS)

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

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

2002-07-01

238

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

PubMed Central

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

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

2009-01-01

239

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

PubMed

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

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

2013-07-24

240

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

PubMed

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

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

2006-07-13

241

Three-dimensional imaging of a geothermal system using temperature and geological models derived from a well-log dataset  

Microsoft Academic Search

The accurate imaging of geothermal systems from the ground surface down to great depths is an interdisciplinary problem common to geothermal resource exploration and development. Rocks can be characterized mainly in terms of their lithology, mineralogy, fracture distribution, permeability, thermal conductivity and porosity, and similarly the geothermal fluid (and its circulation) by its geochemistry, flow pattern, velocity, temperature and pressure.

Yun Teng; Katsuaki Koike

2007-01-01

242

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

243

Quantitative relationships between éeld-measured leaf area index and vegetation index derived from VEGETATION images for paddy rice éelds  

Microsoft Academic Search

In an eVort to develop the quantitative relationships between éeld- measured leaf area index (LAI) and VEGETATION-derived vegetation indices for paddy rice é elds, we have measured LAI of paddy rice é elds at 10-day intervals at é ve sampling sites in Jiangning County, Jiangsu Province of China during the rice growing season (July to October) of 1999, using a

X. XIAO; L. HE; W. SALAS; C. LI; B. MOORE III; R. ZHAO; S. FROLKING; S. BOLES

2002-01-01

244

Tracking Long-Term Survival of Intramyocardially Delivered Human Adipose Tissue-Derived Stem Cells Using Bioluminescence Imaging  

Microsoft Academic Search

Purpose  Transplantation of a regenerative cell population derived from human subcutaneous adipose tissue (hASCs) for cardiac regeneration\\u000a represents a promising therapy due to the capacity of these cells for proliferation and differentiation. Understanding the\\u000a fate of injected hASCs would help to understand how hASCs work in vivo. The aim of this study was to track the long-term fate, including survival, differentiation,

Xiaowen Bai; Yasheng Yan; Michael Coleman; Grace Wu; Brian Rabinovich; Max Seidensticker; Eckhard Alt

245

Synthesis of a potent and selective (18)F-labeled delta-opioid receptor antagonist derived from the Dmt-Tic pharmacophore for positron emission tomography imaging.  

PubMed

Identification and pharmacological characterization of two new selective delta-opioid receptor antagonists, derived from the Dmt-Tic pharmacophore, of potential utility in positron emission tomography (PET) imaging are described. On the basis of its high delta selectivity, H-Dmt-Tic--Lys(Z)-OH (reference compound 1) is a useful starting point for the synthesis of (18)F-labeled compounds prepared by the coupling of N-succinimidyl 4-[ (18)F]fluorobenzoate ([(18)F]SFB) with Boc-Dmt-Tic--Lys(Z)-OH under slightly basic conditions at 37 degrees C for 15 min, deprotection with TFA, and HPLC purification. The total synthesis time was 120 min, and the decay-corrected radiochemical yield of [(18)F]- 1 was about 25-30% ( n = 5) starting from [(18)F]SFB ( n = 5) with an effective specific activity about 46 GBq/micromol. In vitro autoradiography studies showed prominent uptake of [ (18)F]- 1 in the striatum and cortex with significant blocking by 1 and UFP-501 (selective delta-opioid receptor antagonist), suggesting high specific binding of [(18)F]- 1 to delta-opioid receptors. Noninvasive microPET imaging studies revealed the absence of [(18)F]- 1 in rat brain, since it fails to cross the blood-brain barrier. This study demonstrates the suitability of [ (18)F]- 1 for imaging peripheral delta-opioid receptors. PMID:18311909

Ryu, Eun Kyoung; Wu, Zhanhong; Chen, Kai; Lazarus, Lawrence H; Marczak, Ewa D; Sasaki, Yusuke; Ambo, Akihiro; Salvadori, Severo; Ren, Chuancheng; Zhao, Heng; Balboni, Gianfranco; Chen, Xiaoyuan

2008-03-01

246

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

247

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

248

Minimum number of input states required for quantum gate characterization  

NASA Astrophysics Data System (ADS)

We derive an algebraic framework which identifies the minimal information required to assess how well a quantum device implements a desired quantum operation. Our approach is based on characterizing only the unitary part of an open system's evolution. We show that a reduced set of input states is sufficient to estimate the average fidelity of a quantum gate, avoiding a sampling over the full Liouville space. Surprisingly, the minimal set consists of only two input states, independent of the Hilbert-space dimension. The minimal set is, however, impractical for device characterization, since one of the states is a totally mixed thermal state and extracting bounds for the average fidelity is impossible. We therefore present two further reduced sets of input states that allow for, respectively, numerical and analytical bounds on the average fidelity.

Reich, Daniel M.; Gualdi, Giulia; Koch, Christiane P.

2013-10-01

249

Synthesis of 8-[ 18F]fluoroguanine derivatives: in vivo probes for imaging gene expression with positron emission tomography  

Microsoft Academic Search

A new method for the preparation of 8-[18F]fluoroguanine derivatives based on a direct radiofluorination reaction has been developed. The radiofluorination of ganciclovir (1a) with [18F]F2 was carried out in absolute ethanol in the presence of tetraethylammonium hydroxide at room temperature to give 8-[18F]fluoroganciclovir (3a) in an approximately 1% radiochemical yield. Similarly, 8-[18F]fluoropenciclovir (3b), 8-[18F]fluoroacyclovir (3c), and 8-[18F]fluoroguanosine (3d) were synthesized

Mohammad Namavari; Jorge R Barrio; Tatsushi Toyokuni; Sanjiv S Gambhir; Simon R Cherry; Harvey R Herschman; Michael E Phelps; N Satyamurthy

2000-01-01

250

Balancing nutrient inputs to Lake Kivu  

Microsoft Academic Search

The primary production in meromictic Lake Kivu is sustained by external nutrient inputs and by internal loading due to upwelling caused by sub-aquatic sources. We present here the results of external loading of phosphorus (P), nitrogen (N) and silica (Si) by rivers and atmospheric deposition measured from 2006 to 2008. These external inputs are compared to internal loading. The input

Fabrice A. Muvundja; Natacha Pasche; Fred W. B. Bugenyi; Mwapu Isumbisho; Beat Müller; Jean-Népomuscène Namugize; Päivi Rinta; Martin Schmid; Ruth Stierli; Alfred Wüest

2009-01-01

251

Effects of Auditory Input in Individuation Tasks  

ERIC Educational Resources Information Center

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

Robinson, Christopher W.; Sloutsky, Vladimir M.

2008-01-01

252

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

253

7 CFR 3430.15 - Stakeholder input.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Stakeholder input. 3430.15 Section 3430...Solicitation and Application § 3430.15 Stakeholder input. Section 103(c...provide instructions for submission of stakeholder input in the RFA. CSREES will...

2010-01-01

254

7 CFR 3430.15 - Stakeholder input.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Stakeholder input. 3430.15 Section 3430...Solicitation and Application § 3430.15 Stakeholder input. Section 103 (c...provide instructions for submission of stakeholder input in the RFA. CSREES will...

2009-01-01

255

The ALMANAC model's sensitivity to input variables  

Microsoft Academic Search

Crop models often require extensive input data sets to realistically simulate crop growth. Development of such input data sets can be difficult for some model users. The objective of this study was to evaluate the importance of variables in input data sets for crop modeling. Based on published hybrid performance trials in eight Texas counties, we developed standard data sets

Yun Xie; James R. Kiniry; Jimmy R. Williams

2003-01-01

256

Integrality and Separability of Input Devices  

Microsoft Academic Search

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

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

1994-01-01

257

Effects of Auditory Input in Individuation Tasks  

ERIC Educational Resources Information Center

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

Robinson, Christopher W.; Sloutsky, Vladimir M.

2008-01-01

258

Textual Enhancement of Input: Issues and Possibilities  

ERIC Educational Resources Information Center

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

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

2008-01-01

259

Efficient input—output model representations  

Microsoft Academic Search

A family of multivariate representations is presented to capture the input—output relationships of physical systems with many input variables. The high-dimensional model representations (HDMR) are based on the ansatz that for most physical systems, only relatively low order correlations of the input variables will have an impact on the output. Application of the HDMR tools can dramatically reduce the computational

Herschel Rabitz; Ömer F. Ali?; Jeffrey Shorter; Kyurhee Shim

1999-01-01

260

In vivo bioluminescence imaging of magnetically targeted bone marrow-derived mesenchymal stem cells in skeletal muscle injury model.  

PubMed

The purpose of this study is to clarify the kinetics of transplanted mesenchymal stem cells (MSCs) in rat skeletal muscle injury model and the contribution of the magnetic cell delivery system to muscle injury repair. A magnetic field generator was used to apply an external magnetic force to the injury site of the tibia anterior muscle, and 1?×?10(6) MSCs labeled with ferucarbotran-protamine complexes, which were isolated from luciferase transgenic rats, were injected into the injury site. MSCs were injected with and without an external magnetic force (MSC M+ and MSC M- groups, respectively), and phosphate-buffered saline was injected into injury sites as a control. In vivo bioluminescence imaging was performed immediately after the transplantation and, at 12, 24, and 72?h, and 1 and 4 weeks post-transplantation. Also, muscle regeneration and function were histologically and electromechanically evaluated. In vivo bioluminescence imaging showed that the photon of the MSC M+ group was significantly higher than that of the MSC M- group throughout the observation period. In addition, muscle regeneration and function in the MSC M+ group was histologically and functionally better than that of the MSC M- group. The results of our study indicated that magnetic cell delivery system may be of use in directing the transplanted MSCs to the injury site to promote skeletal muscle regeneration. PMID:23192745

Nakabayashi, Akihiro; Kamei, Naosuke; Sunagawa, Toru; Suzuki, Osami; Ohkawa, Shingo; Kodama, Akira; Kamei, Goki; Ochi, Mitsuo

2012-11-28

261

Motion-compensated mega-voltage cone beam CT using the deformation derived directly from 2D projection images.  

PubMed

This paper presents a novel method for respiratory motion compensated reconstruction for cone beam computed tomography (CBCT). The reconstruction is based on a time sequence of motion vector fields, which is generated by a dynamic geometrical object shape model. The dynamic model is extracted from the 2D projection images of the CBCT. The process of the motion extraction is converted into an optimal 3D multiple interrelated surface detection problem, which can be solved by computing a maximum flow in a 4D directed graph. The method was tested on 12 mega-voltage (MV) CBCT scans from three patients. Two sets of motion-artifact-free 3D volumes, full exhale (FE) and full inhale (FI) phases, were reconstructed for each daily scan. The reconstruction was compared with three other motion-compensated approaches based on quantification accuracy of motion and size. Contrast-to-noise ratio (CNR) was also quantified for image quality. The proposed approach has the best overall performance, with a relative tumor volume quantification error of 3.39 ± 3.64% and 8.57 ± 8.31% for FE and FI phases, respectively. The CNR near the tumor area is 3.85 ± 0.42 (FE) and 3.58 ± 3.33 (FI). These results show the clinical feasibility to use the proposed method to reconstruct motion-artifact-free MVCBCT volumes. PMID:23247845

Chen, Mingqing; Cao, Kunlin; Zheng, Yefeng; Siochi, R Alfredo C

2012-12-10

262

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.

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

2013-01-01

263

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

NASA Astrophysics Data System (ADS)

The plasmasphere density distributions and their time variations determine the characteristics of the plasma waves (e.g., hiss, chorus, EMIC) within the plasmasphere and affect the propagation of those waves, which in turn influence the radiation belt dynamics. Therefore, it is necessary to study the plasmaspheric density distribution and to develop reliable models of the plasmaspheric density in order to investigate the wave propagation in the plasmasphere, model the radiation belt, and forecast space weather. A model of the electron densities in the plasmasphere (from the plasmapause location down to the altitude of ~2000 km) is presented. The plasma density is described as a function of L-shell and magnetic latitude. The model is based on the almost instantaneous sounding measurements of the plasma densities along the individual magnetic field lines obtained from the radio plasma imager (RPI) onboard the NASA's IMAGE satellite. The database includes more than 700 electron density profiles, that cover all magnetic local times and range from L = 1.6 to L = 4 spatially. The performance of the model is tested against the data from several satellites and the previously developed models of electron densities in the plasmasphere.

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

2011-12-01

264

An input-balanced realization based adaptive IIR filter using particle swarm optimization  

Microsoft Academic Search

In this paper, based on input-balanced realizations (IBR) and the particle swarm optimization (PSO) technique a novel adaptive IIR filter is proposed. This filter is derived from the input-balanced realization (IBR) that yields an excellent per- formance against finite precision errors. With such a realization, the stability of the adaptive filter can be ensured easily. As well known, the traditional

Yue Wang; Gang Li; Liping Chang

2011-01-01

265

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

266

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

NASA Astrophysics Data System (ADS)

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

Robinson, Mark Southwick

267

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

SciTech Connect

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

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

2009-12-10

268

Multiple-input-multiple-output measurements and modeling in Manhattan  

Microsoft Academic Search

Narrowband multiple-input-multiple-output (MIMO) measurements using 16 transmitters and 16 receivers at 2.11 GHz were carried out in Manhattan. High capacities were found for full, as well as smaller array configurations, all within 80% of the fully scattering channel capacity. Correlation model parameters are derived from data. Spatial MIMO channel capacity statistics are found to be well represented by the separate

Dmitry Chizhik; Jonathan Ling; Peter W. Wolniansky; Reinaldo A. Valenzuela; Nelson Costa; Kris Huber

2003-01-01

269

A storage model with self-similar input  

Microsoft Academic Search

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

Ilkka Norros

1994-01-01

270

A 2.6 inch VGA LCD with Optical Input Function using a 1Transistor Active-Pixel Sensor  

Microsoft Academic Search

A 2.6 inch VGA active-matrix LCD has an integrated optical input function. The optical input function may be used for touch input or fingerprint recognition applications and is achieved by integrating image sensor elements within each display pixel. By using a 1-transistor active-pixel sensor, a 30Hz, 300dpi VGA image sensor is integrated within an LCD with an aperture ratio of

Chris Brown; Ben Hadwen; Hiromi Kato

2007-01-01

271

Validation of a paleo river system derived by ground based electromagnetic induction measurements with satellite based RapidEye images  

NASA Astrophysics Data System (ADS)

Morphological remnants of an inactive river system that has been filled by younger sediments can provide datable proxies about past climatic conditions. However, sediment composition of their infillings is a challenge for agriculture, in particular for precision agriculture. Differential crop development and yield reduction are often a consequence of lateral and vertical textural inhomogeneities. Several studies have shown that buried river systems can be traced by the use of remote sensing. However, the appearance of crop marks strongly depends on environmental conditions, and therefore, the reliance of remotely acquired data can become time and cost expensive. Soil physical properties which are related to textural differences can be mapped fast and cost-effective by the use of near surface geophysics. Especially electromagnetic induction (EMI), which measures soil apparent conductivity (ECa), has become a tool of choice to characterize large areas in high resolution. The introduction of multiple coil EMI systems as well as the quantification of respective measurements enables a reliable multilayer inversion. The aim of this study was to map a postglacial river system on agricultural fields and to mark out buried remains such as trenches and bomb craters of World War II. In summer 2012 ten fields (17 ha) were mapped with the CMD MiniExplorer, a multiple coil EMI system especially appropriate for near surface applications, after the harvest of winter wheat and sugar beet. At elevated sandy sites meander like patterns with higher conductivity were mapped. ECa measurements were verified by textural data taken from directed soil samples and vertical ECa logs. Sediment thickness was evaluated on soil cores and electrical resistivity tomography (ERT) transects. Furthermore, ERT quantified ECa measurements were correlated with satellite as well as destructive derived leaf area index (LAI) measurements. In 3 of 71 LAI maps derived by multispectral RapidEye imagery crop marks were clearly visible following a dry season in spring 2011. These patterns are in coincidence with higher conductivity patterns caused by a higher amount of silt and clay. Good correlations were found for LAI measurements taken during a growing season with underlying sediments especially in the early stages of plant development. Finally, ECa measurements of two heterogeneous fields were used for a 3D layer inversion which will be further implemented into landscape models. This study shows that multiple EMI measurements can be successfully used to recover buried river systems, highlight possible sample locations and support farmers to manage their fields more precisely.

Rudolph, Sebastian; von Hebel, Christian; Ali, Mohammed; Stadler, Anja; Herbst, Michael; Montzka, Carsten; Pätzold, Stefan; Weihermüller, Lutz; van der Kruk, Jan; Vereecken, Harry

2013-04-01

272

2D-Proling: Detecting Input-Dependent Branches with a Single Input Data Set  

Microsoft Academic Search

Static compilers use proling to predict run-time program behavior. A program can behave differently with different input data sets. Aggressively optimized code for one input set can hurt performance when the code is run using a different input set. Hence, compilers need to prole using multiple input sets that can represent a wide range of program behavior. However, using multiple

Hyesoon Kim; M. Aater; Suleman Onur; Mutlu Yale; N. Patt

273

Spectral characterisation of the CARMENES input catalogue  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

274

Comparison of special sensor microwave imager vector wind stress with model-derived and subjective products for the tropical Pacific  

SciTech Connect

The authors address the role of wind data in the development of general ocean circulation model studies. Satellite scatterometry has been proposed, but only minimally implemented, as a means of providing global information on ocean surface wind speed and direction. However, a number of microwave systems have monitored wind speed information on a global scale, some over extended periods of time, which provide day-to-day coverage, compared to the sparse information available from ship or buoy data collections. Recently data from the Defense Meteorological Satellite Program special sensor microwave imager, for the period July 1987 to June 1988 was utilized, in conjunction with conventional data collections to build a model system which included wind directions. The authors here take this data set and use it as a forcing function in a general ocean circulation model study. Their interest is in knowing if this gives results comparable with such data sets built from much more limited observational and subjective analysis. The results are encouraging, and they suggest reexamination of earlier information collections with the idea of reconstructing ocean surface wind speed and direction data sets to be used in further modeling studies.

Busalacchi, A.J.; Atlas, R.M. (NASA Goddard Space Flight Center, Greenbelt, MD (United States)); Hackert, E.C. (Hughes/STX Corp., Lanham, MD (United States))

1993-04-15

275

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

SciTech Connect

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

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

1991-02-01

276

Superparamagnetic iron oxide does not affect the viability and function of adipose-derived stem cells, and superparamagnetic iron oxide-enhanced magnetic resonance imaging identifies viable cells.  

PubMed

The objectives of this study were (1) to determine whether superparamagnetic iron oxide (SPIO) affects viability, transdifferentiation potential and cell-factor secretion of adipose-derived stem cells (ASCs); and (2) to determine whether SPIO-enhanced magnetic resonance (MR) imaging highlights living stem cells. Rat ASCs were incubated in SPIO-containing cell culture medium for 2 days. The SPIO-treated ASCs were then subjected to adipogenic, osteogenic and myogenic transdifferentiation. Expression of vascular endothelial growth factor, hepatocyte growth factor and insulin-like growth factor 1 by the SPIO-treated ASCs was measured using reverse transcription polymerase chain reaction. Cell viability was assessed using trypan blue stain. For in vivo experiments, SPIO-labeled ASCs were injected into 10 rat hearts. The hearts were monitored using MRI. We found that survival rate of the ASCs cultured in the SPIO-containing medium was very high (97-99%). The SPIO-treated ASCs continued to express specific markers for the three types of transdifferentiation. Expression of the cell factors by the ASCs was not affected by SPIO. Signal voids on MR images were associated with the living SPIO-labeled ASCs in the rat hearts. We conclude that SPIO does not affect viability, transdifferentiation potential or cell-factor secretion of ASCs. MRI mainly highlights living SPIO-labeled stem cells. PMID:18657922

Wang, Lei; Deng, Jixian; Wang, Jian; Xiang, Bo; Yang, Tonghua; Gruwel, Marco; Kashour, Tarek; Tomanek, Boguslaw; Summer, Randy; Freed, Darren; Jassal, Davinder S; Dai, Guangping; Glogowski, Miriam; Deslauriers, Roxanne; Arora, Rakesh C; Tian, Ganghong

2008-07-26

277

Synthesis and in vitro biological evaluation of carbon-11-labeled quinoline derivatives as new candidate PET radioligands for cannabinoid CB2 receptor imaging.  

PubMed

Cannabinoids have been recently proposed as a new family of potential antitumor agents, and cannabinoid receptor 2 (CB2) is believed to be over-expressed in tumor cells. This study was designed to develop new radioligands for imaging of CB2 receptor in cancer using biomedical imaging technique positron emission tomography (PET). Carbon-11-labeled 2-oxoquinoline and 2-chloroquinoline derivatives, [(11)C]6a-d and [(11)C]9a-d, were prepared by O-[(11)C]methylation of their corresponding precursors using [(11)C]CH(3)OTf under basic conditions and isolated by a simplified solid-phase extraction (SPE) method in 40-50% radiochemical yields based on [(11)C]CO(2) and decay corrected to end of bombardment (EOB). The overall synthesis time from EOB was 15-20 min, the radiochemical purity was >99%, and the specific activity at end of synthesis (EOS) was 111-185 GBq/micromol. Radioligand binding assays indicated compounds 6f, 6b, and 9f display potent in vitro binding affinities with nanomolar K(i) values and at least 100-2000-fold selectivity for CB2. PMID:20189815

Gao, Mingzhang; Wang, Min; Miller, Kathy D; Hutchins, Gary D; Zheng, Qi-Huang

2010-02-10

278

Fluorescence imaging of mitochondria in living cells using a novel fluorene derivative with a large two-photon absorption cross-section.  

PubMed

We have examined optical properties of a fluorene derivative with two positively charged substituents, 1,1'- diethyl-4,4'-(9,9-diethyl-2,7-fluorenediyl-2,1-ethanediyl)dipyridinium perchlorate (1), in water. The photoluminescence quantum yield of 1 was relatively high (35%) for use as a fluorescent probe in water. We also examined two-photon absorption (TPA) properties of 1 in methanol. The maximum value of the TPA cross-section (730 GM at 750 nm, 1 GM = 10(-50) cm4 s photon-1 molecule-1) was larger than that for most two-photon-excited fluorescent dyes including a classical mitochondria-selective fluorescent dye rhodamine 123. Preliminary fluorescence imaging experiments of the mitochondria in living Paramecium caudatum and HeLa cells were carried out with 1. Bright green fluorescence was observed from the mitochondria in both living cells loaded 1 without toxicity effects. These our results indicate that water-soluble fluorene derivative 1 is a promising candidate as a two-photon-excited fluorescence probe for mitochondria in living cells. PMID:22039816

Tani, Seiji; Nakagawa, Kenta; Honda, Takuya; Saito, Hiromasa; Suzuki, Yasutaka; Kawamata, Jun; Uchida, Makiyo; Sasaki, Akira; Kinjo, Masataka

2012-11-01

279

Accounting for input-model and input-parameter uncertainties in simulation  

Microsoft Academic Search

To account for the input-model and input-parameter uncertainties inherent in many simulations as well as the usual stochastic uncertainty, we present a Bayesian input-modeling technique that yields improved point and confidence-interval estimators for a selected posterior mean response. Exploiting prior information to specify the prior probabilities of the postulated input models and the associated prior input-parameter distributions, we use sample

FAKER ZOUAOUI; JAMES R. WILSON

2004-01-01

280

Impact of metal binding on the antitumor activity and cellular imaging of a metal chelator cationic imidazopyridine derivative.  

PubMed

A new water soluble cationic imidazopyridine species, viz. (1E)-1-((pyridin-2-yl)methyleneamino)-3-(3-(pyridin-2-yl)imidazo[1,5-a]pyridin-2(3H)-yl)propan-2-ol (1), as a metal chelator is prepared as its PF(6) salt and characterized. Compound 1 shows fluorescence at 438 nm on excitation at 342 nm in Tris-HCl buffer giving a fluorescence quantum yield (?) of 0.105 and a life-time of 5.4 ns. Compound 1, as an avid DNA minor groove binder, shows pUC19 DNA cleavage activity in UV-A light of 365 nm forming singlet oxygen species in a type-II pathway. The photonuclease potential of 1 gets enhanced in the presence of Fe(2+), Cu(2+) or Zn(2+). Compound 1 itself displays anticancer activity in HeLa, HepG2 and Jurkat cells with an enhancement on addition of the metal ions. Photodynamic effect of 1 at 365 nm also gets enhanced in the presence of Fe(2+) and Zn(2+). Fluorescence-based cell cycle analysis shows a significant dead cell population in the sub-G1 phase of the cell cycle suggesting apoptosis via ROS generation. A significant change in the nuclear morphology is observed from Hoechst 33258 and an acridine orange/ethidium bromide (AO/EB) dual nuclear staining suggesting apoptosis in cells when treated with 1 alone or in the presence of the metal ions. Apoptosis is found to be caspase-dependent. Fluorescence imaging to monitor the distribution of 1 in cells shows that 1 in the presence of metal ions accumulates predominantly in the cytoplasm. Enhanced uptake of 1 into the cells within 12 h is observed in the presence of Fe(2+) and Zn(2+). PMID:21431236

Roy, Mithun; Chakravarthi, Balabhadrapatruni V S K; Jayabaskaran, Chelliah; Karande, Anjali A; Chakravarty, Akhil R

2011-03-24

281

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

282

High-performance optical input servovalve  

NASA Astrophysics Data System (ADS)

In support of the Fly-by-Light Advanced Systems Hardware (FLASH) Program, Moog has developed and continues to refine a high performance optical input servovalve. This servovalve features no external electrical connections, with all control inputs commanding the valve via an optical fiber. This valve has already demonstrated dynamic and static performance that exceeds most aerospace servovalve requirements, requiring less than 100 milliwatts of optical input power.

Harrington, Carlos

1995-05-01

283

Broadband klystron input and output cavities  

Microsoft Academic Search

A report is given on a method of design of individually broad-banded input and output circuits for use on an experimental broad-band klystron. Multiple-cavity filter design techniques are applied to achieve a bandwidth of seven percent in L-band. The input circuit is comprised of a low Q coaxial cavity tightly coupled to the input cavity. It has a double humped

L. K. Brodersen

1960-01-01

284

Ensemble Color Image Segmentation  

Microsoft Academic Search

\\u000a The subject of this chapter is ensemble color image segmentation. This is an image fusion application in which combine several\\u000a simple image segmentation algorithms to obtain a state-of-the-art image segmentation algorithm. The goal of image segmentation\\u000a is to decompose the input image into a set of meaningful or spatially coherent regions sharing similar attributes. The algorithm\\u000a is often a crucial

H. B. Mitchell

285

Subthreshold dynamics of the neural membrane potential driven by stochastic synaptic input  

NASA Astrophysics Data System (ADS)

In the cerebral cortex, neurons are subject to a continuous bombardment of synaptic inputs originating from the network's background activity. This leads to ongoing, mostly subthreshold membrane dynamics that depends on the statistics of the background activity and of the synapses made on a neuron. Subthreshold membrane polarization is, in turn, a potent modulator of neural responses. The present paper analyzes the subthreshold dynamics of the neural membrane potential driven by synaptic inputs of stationary statistics. Synaptic inputs are considered in linear interaction. The analysis identifies regimes of input statistics which give rise to stationary, fluctuating, oscillatory, and unstable dynamics. In particular, I show that (i) mere noise inputs can drive the membrane potential into sustained, quasiperiodic oscillations (noise-driven oscillations), in the absence of a stimulus-derived, intraneural, or network pacemaker; (ii) adding hyperpolarizing to depolarizing synaptic input can increase neural activity (hyperpolarization-induced activity), in the absence of hyperpolarization-activated currents.

Hillenbrand, Ulrich

2002-08-01

286

Predicting forest structural parameters using the image texture derived from WorldView-2 multispectral imagery in a dryland forest, Israel  

NASA Astrophysics Data System (ADS)

Estimation of forest structural parameters by field-based data collection methods is both expensive and time consuming. Satellite remote sensing is a low-cost alternative in modeling and mapping structural parameters in large forest areas. The current study investigates the potential of using WordView-2 multispectral satellite imagery for predicting forest structural parameters in a dryland plantation forest in Israel. The relationships between image texture features and the several structural parameters such as Number of Trees (NT), Basal Area (BA), Stem Volume (SV), Clark-Evans Index (CEI), Diameter Differentiation Index (DDI), Contagion Index (CI), Gini Coefficient (GC), and Standard Deviation of Diameters at Breast Heights (SDDBH) were examined using correlation analyses. These variables were obtained from 30 m × 30 m square-shaped plots. The Standard Deviation of Gray Levels (SDGL) as a first order texture feature and the second order texture variables based on Gray Level Co-occurrence Matrix (GLCM) were calculated for the pixels that corresponds to field plots. The results of the correlation analysis indicate that the forest structural parameters are significantly correlated with the image texture features. The highest correlation coefficients were calculated for the relationships between the SDDBH and the contrast of red band (r = 0.75, p < 0.01), the BA and the entropy of blue band (r = 0.73, p < 0.01), and the GC and the contrast of blue band (r = 0.71, p < 0.01). Each forest structural parameter was modeled as a function of texture measures derived from the satellite image using stepwise multi linear regression analyses. The determination coefficient (R2) and root mean square error (RMSE) values of the best fitting models, respectively, are 0.38 and 109.56 ha-1 for the NT; 0.54 and 1.79 m2 ha-1 for the BA; 0.42 and 27.18 m3 ha-1 for the SV; 0.23 and 0.16 for the CEI; 0.32 and 0.05 for the DDI; 0.25 and 0.06 for the CI; 0.50 and 0.05 for the GC; and 0.67 and 0.70 for the SDDBH. The leave-one-out cross-validation technique was applied for validation of the best-fitted models (R2 > 0.50). In conclusion, cross-validated statistics confirmed that the structural parameters including the BA, SDDBH, and GC can be predicted and mapped with a reasonable accuracy using the texture features extracted from the spectral bands of WorldView-2 image.

Ozdemir, Ibrahim; Karnieli, Arnon

2011-10-01

287

Heterosynaptic scaling of developing GABAergic synapses: dependence on glutamatergic input and developmental stage.  

PubMed

A proportionality or balance between coactivated excitatory and inhibitory inputs is often observed for individual cortical neurons and is proposed to be important for their functions. This feature of neural circuits may arise from coordinated modulation of excitatory and inhibitory synaptic inputs, a mechanism that remains unknown. Here, in vivo whole-cell recordings from tectal neurons of young Xenopus tadpoles reveals activity-dependent bidirectional modifications of GABAergic inputs. At early developmental stages when GABAergic inputs dominate visually evoked responses, repetitive visual stimulation leads to long-term depression of GABAergic inputs. At later stages when convergent glutamatergic inputs are much stronger, long-term potentiation (LTP) of GABAergic inputs is induced. The polarity of GABAergic plasticity depends on the ratio between the magnitude of coactivated glutamatergic and GABAergic inputs (E/I ratio) to the tectal cell: LTP is induced only when the E/I ratio is above a threshold, and the level of LTP correlates linearly with the logarithm of the E/I ratio. The induction of LTP requires the activation of postsynaptic NMDA receptors, as well as presynaptic TrkB signaling likely through retrograde BDNF (brain-derived neurotrophic factor) and is achieved by overcoming a predominant depression process mediated by NMDA receptors on the presynaptic GABAergic neurons. Our results indicate that the strength of developing GABAergic synapses can be scaled in accordance to coactivated convergent glutamatergic input. This mechanism may contribute to the formation of functional neural circuits with correlated excitatory and inhibitory inputs. PMID:17507553

Liu, Yan; Zhang, Li I; Tao, Huizhong W

2007-05-16

288

High-performance optical input servovalve  

Microsoft Academic Search

In support of the Fly-by-Light Advanced Systems Hardware (FLASH) Program, Moog has developed and continues to refine a high performance optical input servovalve. This servovalve features no external electrical connections, with all control inputs commanding the valve via an optical fiber. This valve has already demonstrated dynamic and static performance that exceeds most aerospace servovalve requirements, requiring less than 100

Carlos Harrington

1995-01-01

289

A new wearable input device: SCURRY  

Microsoft Academic Search

A new wearable input device named SCURRY, developed by the Samsung Advanced Institute of Technology, is introduced in this paper. Based on inertial sensors, this device allows a human operator to select a specified character, an event, or an operation as the input he\\/she wants spatially through both hand motion and finger clicking. It is a glovelike device, which can

Yoon Sang Kim; Byung Seok Soh; Sang-Goog Lee

2005-01-01

290

The Input Hypothesis: An Inside Look.  

ERIC Educational Resources Information Center

|Summarizes and discusses Krashen's "input hypothesis" as presented in his "Principles and Practice in Second Language Acquisition." Suggests that the input hypothesis fails to account convincingly for arrested second language acquisition in an acquisition-rich environment and that it is not directly applicable to U.S. high school and university…

Higgs, Theodore V.

1985-01-01

291

Optimal inputs for linear system identification  

Microsoft Academic Search

This paper considers the design of optimal inputs for identifying parameters in linear dynamic systems. The criterion used for optimization is the sensitivity of the system output to the unknown parameters as expressed by the weighted trace of the Fisher information matrix. It is shown that the optimal energy constrained input is an eigenfunction of a positive self-adjoint operator corresponding

R. Mehra

1974-01-01

292

Maximizing the guessability of symbolic input  

Microsoft Academic Search

Guessability is essential for symbolic input, in which users enter gestures or keywords to indicate characters or commands, or rely on labels or icons to access features. We present a unified approach to both maximizing and evaluating the guessability of symbolic input. This approach can be used by anyone wishing to design a symbol set with high guessability, or to

Jacob O. Wobbrock; Htet Htet Aung; Brandon Rothrock; Brad A. Myers

2005-01-01

293

A new model for handling input  

Microsoft Academic Search

Although there has been important progress in models and packages for the output of graphics to computer screens, there has been little change in the way that input from the mouse, keyboard, and other input devices is handled. New graphics standards are still using a fifteen-year-old model even though it is widely accepted as inadequate, and most modern window managers

Brad A. Myers

1990-01-01

294

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

295

CASSAVA AGRONOMY IN INDIA - LOW INPUT MANAGEMENT  

Microsoft Academic Search

Agronomic research on cassava in India during the past three decades was instrumental in the development of management practices that led to substantial increases in yield, mainly in Tamil Nadu and Kerala. Research efforts have recently focused on the development of low-input technologies with special emphasis on the identification of genotypes adapted to low-input conditions, the utilization of locally available

T. V. R. Nayar; G. Suja; K. Susan John; V. Ravi

296

Human-computer interaction: input devices  

Microsoft Academic Search

All aspects of human-computer interaction, from the high-level concerns of organizational context and system requirements to the conceptual, semantic, syntactic, and lexical levels of user interface design, are ultimately funneled through physical input and output actions and devices. The fundamental task in computer input is to move information from the brain of the user to the computer. Progress in this

Robert J. K. Jacob

1996-01-01

297

Adaptive weighting input estimation for nonlinear systems  

Microsoft Academic Search

This work determines the time-varying load, called input, in a nonlinear system using a novel input estimation inverse algorithm. The algorithm employs the linearised Kalman filter (LKF) with a recursive estimator to determine shocks. The LKF generates the residual innovation sequences, and the estimator uses the residual innovation sequences to evaluate the magnitudes and, therefore, the onset time histories of

Dong-Cherng Lin

2012-01-01

298

Adaptive weighting input estimation for nonlinear systems  

Microsoft Academic Search

This work determines the time-varying load, called input, in a nonlinear system using a novel input estimation inverse algorithm. The algorithm employs the linearised Kalman filter (LKF) with a recursive estimator to determine shocks. The LKF generates the residual innovation sequences, and the estimator uses the residual innovation sequences to evaluate the magnitudes and, therefore, the onset time histories of

Dong-Cherng Lin

2010-01-01

299

Input File Formats - SEER Prep Software  

Cancer.gov

Input data must be stored in either text or compressed text files. If the input file is a text file then it must be named with a .txd extension. A compressed format may be used to reduce the disk space required to store the data.

300

Information leakage of input operation on touch screen monitors caused by electromagnetic noise  

Microsoft Academic Search

It is known that the display image on a personal computer with a monitor can be reconstructed by receiving the electromagnetic noise. Recently, the concern about information leakage in the display image caused by the electromagnetic noise has increased from the aspect of information security. In the present study, the information leakage of input button key operations on touch screen

Hidenori Sekiguchi

2010-01-01

301

Metamodelling with independent and dependent inputs  

NASA Astrophysics Data System (ADS)

In the cases of computationally expensive models the metamodelling technique which maps inputs and outputs is a very useful and practical way of making computations tractable. A number of new techniques which improve the efficiency of the Random Sampling-High dimensional model representation (RS-HDMR) for models with independent and dependent input variables are presented. Two different metamodelling methods for models with dependent input variables are compared. Both techniques are based on a Quasi Monte Carlo variant of RS-HDMR. The first technique makes use of transformation of the dependent input vector into a Gaussian independent random vector and then applies the decomposition of the model using a tensored Hermite polynomial basis. The second approach uses a direct decomposition of the model function into a basis which consists of the marginal distributions of input components and their joint distribution. For both methods the copula formalism is used. Numerical tests prove that the developed methods are robust and efficient.

Zuniga, M. Munoz; Kucherenko, S.; Shah, N.

2013-06-01

302

Retinomorphic image processing.  

PubMed

The present work is aimed at understanding and explaining some of the aspects of visual signal processing at the retinal level while exploiting the same towards the development of some simple techniques in the domain of digital image processing. Classical studies on retinal physiology revealed the nature of contrast sensitivity of the receptive field of bipolar or ganglion cells, which lie in the outer and inner plexiform layers of the retina. To explain these observations, a difference of Gaussian (DOG) filter was suggested, which was subsequently modified to a Laplacian of Gaussian (LOG) filter for computational ease in handling two-dimensional retinal inputs. Till date almost all image processing algorithms, used in various branches of science and engineering had followed LOG or one of its variants. Recent observations in retinal physiology however, indicate that the retinal ganglion cells receive input from a larger area than the classical receptive fields. We have proposed an isotropic model for the non-classical receptive field of the retinal ganglion cells, corroborated from these recent observations, by introducing higher order derivatives of Gaussian expressed as linear combination of Gaussians only. In digital image processing, this provides a new mechanism of edge detection on one hand and image half-toning on the other. It has also been found that living systems may sometimes prefer to "perceive" the external scenario by adding noise to the received signals in the pre-processing level for arriving at better information on light and shade in the edge map. The proposed model also provides explanation to many brightness-contrast illusions hitherto unexplained not only by the classical isotropic model but also by some other Gestalt and Constructivist models or by non-isotropic multi-scale models. The proposed model is easy to implement both in the analog and digital domain. A scheme for implementation in the analog domain generates a new silicon retina model implemented on a hardware development platform. PMID:18166395

Ghosh, Kuntal; Bhaumik, Kamales; Sarkar, Sandip

2008-01-01

303

Closed-loop input and output impedances of DC-DC switching converters operating in voltage and current mode control  

Microsoft Academic Search

This work derives the closed-loop input and output impedances of three major types of DC-DC converters (Buck, Boost, and Buck-Boost) operating in voltage or current mode control. First, it introduces the small-signal converter model employed to derive the input and output impedances. Next, it reviews open-loop impedances for use in simplifying the expressions developed for closed-loop impedances. It then derives

Reza Ahmadi; Darren Paschedag; Mehdi Ferdowsi

2010-01-01

304

Multispectral imaging of the olfactory bulb activation: influence of realistic differential pathlength correction factors on the derivation of oxygenation and total hemoglobin concentration maps  

NASA Astrophysics Data System (ADS)

In vivo multispectral reflectance imaging has been extensively used in the somatosensory cortex (SsC) in anesthetized rodents to collect intrinsic signal during activation and derive hemodynamics signals time courses. So far it has never been applied to the Olfactory Bulb (OB), although this structure is particularly well suited to the optical study of brain activation due to the its well defined organization, the ability to physiologically activate it with odorants, and the low depth of the activated layers. To obtain hemodynamics parameters from reflectance variations data, it is necessary to take into account a corrective factor called Differential Pathlength (DP). It is routinely estimated using Monte Carlo simulations, modeling photons propagation in simplified infinite geometry tissue models. The first goal of our study was to evaluate the influence of more realistic layered geometries and optical properties on the calculation of DP and ultimately on the estimation of the hemodynamics parameters. Since many valuable results have been obtained previously by others in the SSc, for the purpose of validation and comparison we performed Monte Carlo simulations in both the SSC and the OB. We verified the assumption of constant DP during activation by varying the hemoglobin oxygen saturation, total hemoglobin concentration and we also studied the effect of a superficial bone layer on DP estimation for OB. The simulations show the importance of defining a finite multilayer model instead of the coarse infinite monolayer model, especially for the SSc, and demonstrate the need to perform DP calculation for each structure taking into account their anatomofunctional properties. The second goal of the study was to validate in vivo multispectral imaging for the study of hemodynamics in the OB during activation. First results are presented and discussed.

Renaud, R.; Gurden, H.; Chery, R.; Bendhamane, M.; Martin, C.; Pain, F.

2011-02-01

305

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.

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

2012-01-01

306

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

307

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.

2008-04-01

308

RELATIVE INPUT STRENGTH RAPIDLY REGULATES DENDRITIC STRUCTURE of CHICK auditory brainstem NEURONS  

PubMed Central

Competition between presynaptic inputs has been suggested to shape dendritic form. This hypothesis can be directly tested on bitufted, auditory neurons in chicken nucleus laminaris (NL). Each NL neuron contains two relatively symmetrical dendritic arbors; the dorsal dendrite receives excitatory glutamatergic input from the ipsilateral ear and the ventral dendrites receive corresponding input from the contralateral ear. To assess the effect of relative synaptic strength on NL dendrites, we used single cell electroporation, electrophysiology and live, two-photon laser scanning microscopy to manipulate both the amount and the balance of synaptic input to the two matching sets of dendrites. With simultaneous activation, both sets of dendrites changed together, either growing or retracting over the imaging period. In contrast, stimulation of only one set of dendrites (either dorsal or ventral) resulted in the unstimulated dendrites losing total dendritic branch length, while the stimulated dendrites exhibited a tendency to grow. In this system, balanced input leads to balanced changes in the two sets of dendrites while imbalanced input results in differential changes. Time-lapse imaging revealed that NL dendrites respond to differential stimulation by first decreasing the size of their unstimulated dendrites, and then increasing the size of their stimulated dendrites. This result suggests that the relative activity of presynaptic neurons dynamically controls dendritic structure in NL, and that dendritic real estate can rapidly be shifted from inactive inputs to active inputs.

Sorensen, Staci A.; Rubel, Edwin W.

2011-01-01

309

Kernel principal component analysis for stochastic input model generation  

SciTech Connect

Highlights: {yields} KPCA is used to construct a reduced order stochastic model of permeability. {yields} A new approach is proposed to solve the pre-image problem in KPCA. {yields} Polynomial chaos is used to provide a parametric stochastic input model. {yields} Flow in porous media with channelized permeability is considered. - Abstract: Stochastic analysis of random heterogeneous media provides useful information only if realistic input models of the material property variations are used. These input models are often constructed from a set of experimental samples of the underlying random field. To this end, the Karhunen-Loeve (K-L) expansion, also known as principal component analysis (PCA), is the most popular model reduction method due to its uniform mean-square convergence. However, it only projects the samples onto an optimal linear subspace, which results in an unreasonable representation of the original data if they are non-linearly related to each other. In other words, it only preserves the first-order (mean) and second-order statistics (covariance) of a random field, which is insufficient for reproducing complex structures. This paper applies kernel principal component analysis (KPCA) to construct a reduced-order stochastic input model for the material property variation in heterogeneous media. KPCA can be considered as a nonlinear version of PCA. Through use of kernel functions, KPCA further enables the preservation of higher-order statistics of the random field, instead of just two-point statistics as in the standard Karhunen-Loeve (K-L) expansion. Thus, this method can model non-Gaussian, non-stationary random fields. In this work, we also propose a new approach to solve the pre-image problem involved in KPCA. In addition, polynomial chaos (PC) expansion is used to represent the random coefficients in KPCA which provides a parametric stochastic input model. Thus, realizations, which are statistically consistent with the experimental data, can be generated in an efficient way. We showcase the methodology by constructing a low-dimensional stochastic input model to represent channelized permeability in porous media.

Ma Xiang [Materials Process Design and Control Laboratory, Sibley School of Mechanical and Aerospace Engineering, 101 Frank H.T. Rhodes Hall, Cornell University, Ithaca, NY 14853-3801 (United States); Zabaras, Nicholas, E-mail: zabaras@cornell.edu [Materials Process Design and Control Laboratory, Sibley School of Mechanical and Aerospace Engineering, 101 Frank H.T. Rhodes Hall, Cornell University, Ithaca, NY 14853-3801 (United States)

2011-08-10

310

Bootstrap Resampling for Voxel-wise Variance Analysis of Three-dimensional Density Maps Derived by Image Analysis of Two-dimensional Crystals  

PubMed Central

Difference density maps are commonly used in structural biology for identifying conformational changes in macromolecular complexes. For interpretation of the results, it is essential to estimate the variance or standard deviation of the difference density and the distribution of errors in space. In order to compare three-dimensional density maps of gap junction channels with and without the C-terminal regulatory domain, we developed a bootstrap-resampling method for estimation of the voxel-wise standard deviation. The bootstrap approach has been successfully used for estimating the sampling distribution from a limited data set and for estimating the statistical properties of the derived quantities [Efron, B. Ann. Statist. 7, 1 (1979)]. In our application, the standard deviation map can be estimated by bootstrapping the images. Our result showed that, apart from the symmetry axes and small regions bordering the lumen of the extracellular vestibule, difference maps normalized by the mean of the standard deviation map can be used as a good approximation of the t-test map of the gap junction crystals.

Cheng, Anchi; Yeager, Mark

2010-01-01

311

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

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 10(7) 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; Janic, Branislava

2013-08-09

312

High throughput measurement of Ca²? dynamics for drug risk assessment in human stem cell-derived cardiomyocytes by kinetic image cytometry.  

PubMed

Current methods to measure physiological properties of cardiomyocytes and predict fatal arrhythmias that can cause sudden death, such as Torsade de Pointes, lack either the automation and throughput needed for early-stage drug discovery and/or have poor predictive value. To increase throughput and predictive power of in vitro assays, we developed kinetic imaging cytometry (KIC) for automated cell-by-cell analyses via intracellular fluorescence Ca²? indicators. The KIC instrument simultaneously records and analyzes intracellular calcium concentration [Ca²?](i) at 30-ms resolution from hundreds of individual cells/well of 96-well plates in seconds, providing kinetic details not previously possible with well averaging technologies such as plate readers. Analyses of human embryonic stem cell and induced pluripotent stem cell-derived cardiomyocytes revealed effects of known cardiotoxic and arrhythmogenic drugs on kinetic parameters of Ca²? dynamics, suggesting that KIC will aid in the assessment of cardiotoxic risk and in the elucidation of pathogenic mechanisms of heart disease associated with drugs treatment and/or genetic background. PMID:22926323

Cerignoli, Fabio; Charlot, David; Whittaker, Ross; Ingermanson, Randy; Gehalot, Piyush; Savchenko, Alex; Gallacher, David J; Towart, Rob; Price, Jeffrey H; McDonough, Patrick M; Mercola, Mark

2012-08-25

313

Intravoxel incoherent motion MR imaging for prostate cancer: an evaluation of perfusion fraction and diffusion coefficient derived from different b-value combinations.  

PubMed

There has been a resurgent interest in intravoxel incoherent motion (IVIM) MR imaging to obtain perfusion as well as diffusion information on lesions, in which the diffusion was modeled as Gaussian diffusion. However, it was observed that this diffusion deviated from expected monoexponential decay at high b-values and the reported perfusion in prostate is contrary to the findings in dynamic contrast-enhanced (DCE) MRI studies and angiogenesis. Thus, this work is to evaluate the effect of different b-values on IVIM perfusion fractions (f) and diffusion coefficients (D) for prostate cancer detection. The results show that both parameters depended heavily on the b-values, and those derived without the highest b-value correlated best with the results from DCE-MRI studies; specifically, f was significantly elevated (7.2% vs. 3.7%) in tumors when compared with normal tissues, in accordance with the volume transfer constant (K(trans); 0.39 vs. 0.18 min(-1)) and plasma fractional volume (v(p) ; 8.4% vs. 3.4%). In conclusion, it is critical to choose an appropriate range of b-values in studies or include the non-Gaussian diffusion contribution to obtain unbiased IVIM measurements. These measurements could eliminate the need for DCE-MRI, which is especially relevant in patients who cannot receive intravenous gadolinium-based contrast media. PMID:22488794

Pang, Yuxi; Turkbey, Baris; Bernardo, Marcelino; Kruecker, Jochen; Kadoury, Samuel; Merino, Maria J; Wood, Bradford J; Pinto, Peter A; Choyke, Peter L

2012-04-09

314

High Throughput Measurement of Ca2+ Dynamics for Drug Risk Assessment in Human Stem Cell-derived Cardiomyocytes by Kinetic Image Cytometry  

PubMed Central

Current methods to measure physiological properties of cardiomyocytes and predict fatal arrhythmias that can cause sudden death, such as Torsade de Pointes, lack either the automation and throughput needed for early-stage drug discovery and/or have poor predictive value. To increase throughput and predictive power of in vitro assays, we developed kinetic imaging cytometry (KIC) for automated cell-by-cell analyses via intracellular fluorescence Ca2+ indicators. The KIC instrument simultaneously records and analyzes intracellular calcium concentration [Ca2+]i at 30-ms resolution from hundreds of individual cells/well of 96-well plates in seconds, providing kinetic details not previously possible with well averaging technologies such as plate readers. Analyses of human embryonic stem cell and induced pluripotent stem cell-derived cardiomyocytes revealed effects of known cardiotoxic and arrhythmogenic drugs on kinetic parameters of Ca2+ dynamics, suggesting that KIC will aid in the assessment of cardiotoxic risk and in the elucidation of pathogenic mechanisms of heart disease associated with drugs treatment and/or genetic background.

Cerignoli, Fabio; Charlot, David; Whittaker, Ross; Ingermanson, Randy; Gehalot, Piyush; Savtchenko, Alex; Gallacher, David J.; Towart, Rob; Price, Jeffrey H.; McDonough, Patrick M.; Mercola, Mark

2013-01-01

315

Design, Synthesis, and Evaluation of 1,4,7,10-Tetraazacyclododecane-1,4,7-triacetic Acid-Derived, Redox-Sensitive Contrast Agents for Magnetic Resonance Imaging  

PubMed Central

The design and synthesis of three 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) derivatives bearing linkers with terminal thiol groups and a preliminary evaluation of their potential for use in assembling redox-sensitive Magnetic Resonance Imaging (MRI) contrast agents are reported. The linkers were selected based on computational docking with a crystal structure of human serum albumin (HSA). Gd(III)-DO3A and Eu(III)-DO3A complexes were synthesized, and the structure of one complex was established by X-ray crystallographic analysis. The binding to HSA of a Gd(III)-DO3A complex bearing a thiol-terminated 3,6-dioxanonyl chain was competitively inhibited by homocysteine and by the corresponding Eu chelate. Binding to HSA was abolished when the terminal thiol group of this complex was absent. The longitudinal water-proton relaxivities (r1) of the three Gd(III)-DO3A complexes and of two Gd(III)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) complexes were measured in saline at 7 Tesla. The DO3A complexes exhibited smaller r1 values, in both bound and free states, than the DOTA complexes.

Raghunand, Natarajan; Guntle, Gerald P.; Gokhale, Vijay; Nichol, Gary S.; Mash, Eugene A.; Jagadish, Bhumasamudram

2010-01-01

316

Novel ¹?F-labeled benzoxazole derivatives as potential positron emission tomography probes for imaging of cerebral ?-amyloid plaques in Alzheimer's disease.  

PubMed

Two radiofluoro-pegylated phenylbenzoxazole derivatives, 4-(5-(2-(2-(2-[(18)F]fluoroethoxy)ethoxy)ethoxy)benzo[d]oxazol-2-yl)-N-methylaniline ([(18)F]24) and 4-(5-(2-(2-(2-[(18)F]fluoroethoxy)ethoxy)ethoxy)benzo[d]oxazol-2-yl)-N,N-dimethylaniline ([(18)F]32), were synthesized and evaluated as probes for imaging cerebral ?-amyloid (A?) plaques in living brain tissue by PET. [(18)F]24 and [(18)F]32 displayed high affinity for A?(1-42) aggregates (K(i) = 9.3 and 3.9 nM, respectively). In vitro autoradiography with sections of post-mortem AD brain and transgenic mouse brain confirmed the affinity of these tracers. Initial high uptake into and rapid washout from the brain in normal mice were observed. [(18)F]24 also displayed excellent binding to A? plaques in ex vivo autoradiographic experiments with Tg2576 mice. Furthermore, small-animal PET studies demonstrated significant differences in the clearance profile after the administration of [(18)F]24 between Tg2576 and wild-type mice. The results suggest [(18)F]24 to be a useful PET agent for detecting A? plaques in the living human brain. PMID:22690944

Cui, Mengchao; Ono, Masahiro; Kimura, Hiroyuki; Ueda, Masashi; Nakamoto, Yuji; Togashi, Kaori; Okamoto, Yoko; Ihara, Masafumi; Takahashi, Ryosuke; Liu, Boli; Saji, Hideo

2012-06-12

317

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

318

Optical correlation and convolution of real 2D inputs and real 2D filters  

NASA Astrophysics Data System (ADS)

Frequently in character recognition, there is a need to correlate or convolve purely real 2D inputs and real 2D filters. We propose two optical correlators. The first, basic real-input-real-filter optical correlator, adds x and y mirror images adjacent to the image to generate real and even images. This avoids the need for an offset reference to capture phase. Therefore, we have greater diffraction efficiency and a reduction in filter LCD pixel size. The second, Hilbert transform basic real-input-real-filter optical correlator, uses a Hilbert transform by masking in the filter plane to reduce the number elements in the filter LCD to that of the number of pixels in a filter image. An optical system can generate the mirror images in real time so that both the input LCD and the filter LCD can have only the same number of elements as their respective number of image pixels. We show how a spatial filter can be used to remove the intensity offset produced in the Hilbert transform and restore shift invariance if required. Finally, if desired, some rotation invariance can be achieved by overlapping the mirror images with the basic correlator. Advantages and disadvantages of the proposed correlators are discussed.

McAulay, Alastair D.

1999-10-01

319

Neutron field imaging with microchannel plates  

NASA Astrophysics Data System (ADS)

Rapid and spatially resolved imaging of neutron fields is not a well-developed technology relative to photon- and electron- based imaging techniques, However, glass-based microchannel plate (MCP) technology is relatively mature, enabling its application to neutron imaging to be straightforward. NOVA's approach to improved neutron detection efficiency and spatial resolution is derived from the suggestion of Fraser and Pearson, where 10B is directly incorporated into the glass matrix of the MCP structure. The 10B(n,(alpha) )7Li capture conversion stimulates the emission of secondary electrons into the adjacent microchannel structure. An electron cascade ensues, amplifying the detection event into a subnanosecond electron pulse emitted from the microchannel. The pulse can be electronically registered by a radiation-hard readout device and processed as a digital image. The image corresponds to spatial variations in the neutron flux striking the MCP input face. NOVA has constructed and tested a number of prototype neutron imaging detectors using cold and thermal neutron beams at the NIST Center for Neutron Research (NCNR) in Gaithersburg, MD. Features having a spatial separation of 30 micrometer are clearly resolvable in the raw images. Software processing further improves the image resolution. Conversion efficiency for thermal neutrons of an initial iteration of the specially modified MCPs is approximately 20%, with negligible gamma ray-induced background. In-progress modifications to the MCP base material and structure should produce imaging detectors with neutron detection efficiencies that exceed 50%.

Feller, W. Bruce; Downing, Robert G.; White, Paul L.

2000-11-01

320

Virtual Image Display for Space Flight Simulator.  

National Technical Information Service (NTIS)

This report describes the addition of virtual display imagery to a spacecraft rendezvous and docking simulator. The virtual image display is an optical system which accepts inputs from two image generators and produces a superimposed, virtual image. The m...

T. P. Neuberger W. E. Myles U. W. Ludwig

1966-01-01

321

Micromachined dual input axis rate gyroscope  

NASA Astrophysics Data System (ADS)

The need for inexpensive yet reliable angular rate sensors in fields ranging from automotive to consumer electronics has motivated prolific micromachined rate gyroscope research. The vast majority of research has focused on single input axis rate gyroscopes based upon either translational resonance, such as tuning forks, or structural mode resonance, such as vibrating rings. However, this work presents a novel, contrasting approach based on angular resonance of a rotating rigid rotor suspended by torsional springs. The inherent symmetry of the circular design allows angular rate measurement about two axes simultaneously, hence the name micromachined dual-axis rate gyroscope. The underlying theory of operation, mechanical structure design optimization, electrical interface circuitry, and signal processing are described in detail. Several operational versions were fabricated using two different fully integrated surface micromachining processes as proof of concept. The heart of the dual-axis rate gyroscope is a ˜2 mum thick polysilicon disk or rotor suspended above the substrate by a four beam suspension. When this rotor in driven into angular oscillation about the axis perpendicular to the substrate, a rotation rate about the two axes parallel to the substrate invokes an out of plane rotor tilting motion due to Coriolis acceleration. This tilting motion is capacitively measured and on board integrated signal processing provides two output voltages proportional to angular rate input about the two axes parallel to the substrate. The design process begins with the derivation of gyroscopic dynamics. The equations suggest that tuning sense mode frequencies to the drive oscillation frequency can vastly increase mechanical sensitivity. Hence the supporting four beam suspension is designed such that electrostatic tuning can match modes despite process variations. The electrostatic tuning range is limited only by rotor collapse to the substrate when tuning-voltage induced electrostatic forces over power the beam suspension. Multivariable design optimization is used to maximize performance given process constraints. All electronics needed to sustain rotor oscillation, control oscillation amplitude, sense rotor tilting due to Coriolis acceleration, and process sense signals to produce voltage outputs are explained. A voltage controlled oscillator slaved to the structure oscillation through a phase-lock-loop is used as the master clock to produce all signals needed for signal processing and amplitude control. Thus, the micromachine serves as both a rotation sensor and a frequency reference. Final versions fabricated by Sandia National Laboratory were fully integrated and therefore required only passive components and electrical sources off-chip. Without electrostatic tuning, dual-axis rate gyroscopes achieved 0.1sp°/sec/sqrt{Hz} noise level. This provided automotive grade performance of approximately 1sp°/sec noise floor over a 100 Hz bandwidth. Electrical tuning decreased noise to below 0.02sp°/sec/sqrt{Hz}. However, open-loop operation with nearly matched sense and drive modes can result in higher cross-axis sensitivity, scale factor drift, and phase errors. Closed-loop feedback methods which alleviate these problems as well as reduce offset drift due to quadrature error are presented as future directions.

Juneau, Thor Nelson

322

Distribution of Earthquake Input Energy in Structures.  

National Technical Information Service (NTIS)

In developing an energy-based design approach and assessing the damage potential of structures, one must know the distribution of earthquake input energy among energy components: kinetic, elastic strain, hysteretic, and damping. The report examines the in...

P. Khashaee B. Mohraz F. SAdek H. S. Lew J. L. Gross

2003-01-01

323

Spectral properties of the Preisach hysteresis model with random input. I. General results  

NASA Astrophysics Data System (ADS)

We derive exact results for the spectral density S(?) of the output of the Preisach model, a standard model for complex, nonlocal hysteresis. We obtain general results for uncorrelated input signals with arbitrary input and Preisach densities. It is shown analytically that uncorrelated input signals are transformed into output exhibiting long-time correlations. For the simplest example of uniform input and Preisach distributions we prove that correlations decay asymptotically with a t-3 power law corresponding to a logarithmic low frequency divergence of the second derivative of the spectrum S(?) . A simpler expression for symmetric Preisach models is also obtained, which is discussed in detail in Part II, showing that long-time tails or even 1/f noise are general features of this class of models.

Radons, Günter

2008-06-01

324

Input-Output-to-State Stability  

Microsoft Academic Search

This work explores Lyapunov characterizations of the input-output-to-state stability (IOSS) property for nonlinear systems. The notion of IOSS is a natural generalization of the standard zero-detectability property used in the linear case. The main contribution of this work is to establish a complete equivalence between the input-output-to-state stability property and the existence of a certain type of smooth Lyapunov function.

Mikhail Krichmanand; Eduardo D. Sontag; Yuan Wang

1999-01-01

325

Input-Output-to-State Stability  

Microsoft Academic Search

This work explores Lyapunov characterizations of the input-output-to-state stability (ioss) property for nonlinear systems. The notion of ioss is a natural generalization of the standard zero-detectability property used in the linear case. The main contribution of this work is to establish a complete equivalence between the input-output-to-state stability property and the existence of a certain type of smooth Lyapunov function.

Mikhail Krichman; Eduardo D. Sontag; Yuan Wang

2001-01-01

326

Multi-touch surface as input device  

Microsoft Academic Search

In consideration of the rapid development of displays and multi-touch technologies, many workspaces could feature integrated multi-touch displays in the near future and therefore the possibility of using them as input devices for other computers needs to be reviewed. The idea is, to get rid of many different input devices (e.g. keyboard, mouse, multi-touch-pad) by using a single multi-touch display.

Andreas Dippon

2010-01-01

327

Fair Scheduling for Input-Queued Switches  

Microsoft Academic Search

Input-queued switch architecture has become attractive for implementing high performance routers because the switching fabric and the buffer need not run at a multiple of input link's rate. It is challenging to provide a scheduling technique that is both highly efficient and fair in resource allocation. We propose an iterative cell-based fair scheduling (iCFS) scheme, based on SLIP that support

C. Roidel; N. Razavi; M. Analoui

2006-01-01

328

A new unit cell design with automatic input stage selection capability for increased SNR  

NASA Astrophysics Data System (ADS)

This paper presents novel unit cell architecture for short wave infrared (SWIR) imaging applications. It has two input stages which are CTIA and SFD covering for both respectively low and high light levels and automatic input stage selection circuitry that chooses best input stage. A user can select 2 modes for FPA manual and automatic mode. In manual mode, user can set CTIA or SFD for all pixels according to user needs. In automatic mode, each pixel selects input stage itself according to light level. Automatic input stage selection for each pixel brings high SNR level and low noise along with highest possible dynamic range. Standard CMOS 0.18µm TSMC technology is used to realize unit cell. In the architecture of unit cell, circuit level techniques are used to optimize layout size.

Yazici, Melik; Kayahan, Huseyin; Ceylan, Omer; Gurbuz, Yasar

2013-06-01

329

Significance of input correlations in striatal function.  

PubMed

The striatum is the main input station of the basal ganglia and is strongly associated with motor and cognitive functions. Anatomical evidence suggests that individual striatal neurons are unlikely to share their inputs from the cortex. Using a biologically realistic large-scale network model of striatum and cortico-striatal projections, we provide a functional interpretation of the special anatomical structure of these projections. Specifically, we show that weak pairwise correlation within the pool of inputs to individual striatal neurons enhances the saliency of signal representation in the striatum. By contrast, correlations among the input pools of different striatal neurons render the signal representation less distinct from background activity. We suggest that for the network architecture of the striatum, there is a preferred cortico-striatal input configuration for optimal signal representation. It is further enhanced by the low-rate asynchronous background activity in striatum, supported by the balance between feedforward and feedback inhibitions in the striatal network. Thus, an appropriate combination of rates and correlations in the striatal input sets the stage for action selection presumably implemented in the basal ganglia. PMID:22125480

Yim, Man Yi; Aertsen, Ad; Kumar, Arvind

2011-11-17

330

Influential input classification in probabilistic multimedia models  

SciTech Connect

Monte Carlo analysis is a statistical simulation method that is often used to assess and quantify the outcome variance in complex environmental fate and effects models. Total outcome variance of these models is a function of (1) the uncertainty and/or variability associated with each model input and (2) the sensitivity of the model outcome to changes in the inputs. To propagate variance through a model using Monte Carlo techniques, each variable must be assigned a probability distribution. The validity of these distributions directly influences the accuracy and reliability of the model outcome. To efficiently allocate resources for constructing distributions one should first identify the most influential set of variables in the model. Although existing sensitivity and uncertainty analysis methods can provide a relative ranking of the importance of model inputs, they fail to identify the minimum set of stochastic inputs necessary to sufficiently characterize the outcome variance. In this paper, we describe and demonstrate a novel sensitivity/uncertainty analysis method for assessing the importance of each variable in a multimedia environmental fate model. Our analyses show that for a given scenario, a relatively small number of input variables influence the central tendency of the model and an even smaller set determines the shape of the outcome distribution. For each input, the level of influence depends on the scenario under consideration. This information is useful for developing site specific models and improving our understanding of the processes that have the greatest influence on the variance in outcomes from multimedia models.

Maddalena, Randy L.; McKone, Thomas E.; Hsieh, Dennis P.H.; Geng, Shu

1999-05-01

331

Significance of Input Correlations in Striatal Function  

PubMed Central

The striatum is the main input station of the basal ganglia and is strongly associated with motor and cognitive functions. Anatomical evidence suggests that individual striatal neurons are unlikely to share their inputs from the cortex. Using a biologically realistic large-scale network model of striatum and cortico-striatal projections, we provide a functional interpretation of the special anatomical structure of these projections. Specifically, we show that weak pairwise correlation within the pool of inputs to individual striatal neurons enhances the saliency of signal representation in the striatum. By contrast, correlations among the input pools of different striatal neurons render the signal representation less distinct from background activity. We suggest that for the network architecture of the striatum, there is a preferred cortico-striatal input configuration for optimal signal representation. It is further enhanced by the low-rate asynchronous background activity in striatum, supported by the balance between feedforward and feedback inhibitions in the striatal network. Thus, an appropriate combination of rates and correlations in the striatal input sets the stage for action selection presumably implemented in the basal ganglia.

Yim, Man Yi; Aertsen, Ad; Kumar, Arvind

2011-01-01

332

3D and Appearance Modeling from Images  

NASA Astrophysics Data System (ADS)

This paper gives an overview of works done in our group on 3D and appearance modeling of objects, from images. The backbone of our approach is to use what we consider as the principled optimization criterion for this problem: to maximize photoconsistency between input images and images rendered from the estimated surface geometry and appearance. In initial works, we have derived a general solution for this, showing how to write the gradient for this cost function (a non-trivial undertaking). In subsequent works, we have applied this solution to various scenarios: recovery of textured or uniform Lambertian or non-Lambertian surfaces, under static or varying illumination and with static or varying viewpoint. Our approach can be applied to these different cases, which is possible since it naturally merges cues that are often considered separately: stereo information, shading, silhouettes. This merge naturally happens as a result of the cost function used: when rendering estimated geometry and appearance (given known lighting conditions), the resulting images automatically contain these cues and their comparison with the input images thus implicitly uses these cues simultaneously.

Sturm, Peter; Delaunoy, Amaël; Gargallo, Pau; Prados, Emmanuel; Yoon, Kuk-Jin

333

Temporal precision of spike response to fluctuating input in pulse-coupled networks of oscillating neurons.  

PubMed

A single neuron is known to generate almost identical spike trains when the same fluctuating input is repeatedly applied. Here, we study the reliability of spike firing in a pulse-coupled network of oscillator neurons receiving fluctuating inputs. We can study the precise responses of the network as synchronization between uncoupled copies of the network by a common noisy input. To study the noise-induced synchronization between networks, we derive a self-consistent equation for the distribution of spike-time differences between the networks. Solving this equation, we elucidate how the spike precision changes as a function of the coupling strength. PMID:19113676

Teramae, Jun-nosuke; Fukai, Tomoki

2008-12-12

334

Distribution of return point memory states for systems with stochastic inputs  

NASA Astrophysics Data System (ADS)

We consider the long term effect of stochastic inputs on the state of an open loop system which exhibits the so-called return point memory. An example of such a system is the Preisach model; more generally, systems with the Preisach type input-state relationship, such as in spin-interaction models, are considered. We focus on the characterisation of the expected memory configuration after the system has been effected by the input for sufficiently long period of time. In the case where the input is given by a discrete time random walk process, or the Wiener process, simple closed form expressions for the probability density of the vector of the main input extrema recorded by the memory state, and scaling laws for the dimension of this vector, are derived. If the input is given by a general continuous Markov process, we show that the distribution of previous memory elements can be obtained from a Markov chain scheme which is derived from the solution of an associated one-dimensional escape type problem. Formulas for transition probabilities defining this Markov chain scheme are presented. Moreover, explicit formulas for the conditional probability densities of previous main extrema are obtained for the Ornstein-Uhlenbeck input process. The analytical results are confirmed by numerical experiments.

Amann, A.; Brokate, M.; Rachinskii, D.; Temnov, G.

2011-01-01

335

Novel pentameric thiophene derivatives for in vitro and in vivo optical imaging of a plethora of protein aggregates in cerebral amyloidoses  

PubMed Central

Molecular probes for selective identification of protein aggregates are important to advance our understanding of the molecular pathogenesis underlying cerebral amyloidoses. Here we report the chemical design of pentameric thiophene derivatives, denoted luminescent conjugated oligothiophenes (LCOs), which could be used for real-time visualization of cerebral protein aggregates in transgenic mouse models of neurodegenerative diseases by multiphoton microscopy. One of the LCOs, p-FTAA, showed conformation-dependent optical properties and could be utilized for ex vivo spectral assignment of distinct prion deposits from two mouse-adapted prion strains. p-FTAA also revealed staining of transient soluble pre-fibrillar non-thioflavinophilic A?- assemblies during in vitro fibrillation of A? peptides. In brain tissue samples, A? deposits and neurofibrillary tangles (NFTs) were readily identified by a strong fluorescence from p-FTAA and the LCO staining showed complete co-localization with conventional antibodies (6E10 and AT8), indicating that p-FTAA detects all the immuno-positive aggregated proteinaceous species in Alzheimer disease, but with significantly shorter imaging time (100 fold) compared to immunofluorescence. In addition, a patchy islet-like staining of individual A? plaque was unveiled by the anti-oligomer A11 antibody during co-staining with p-FTAA, suggesting that pre-fibrillar species are likely an intrinsic component of A? plaques in human brain. The major hallmarks of Alzheimer’s disease, namely A? aggregates versus NFTs could also be distinguished due to distinct emission spectra from p-FTAA. Overall, we demonstrate that LCOs can be utilized as powerful practical research tools for studying protein aggregation diseases and facilitate the study of amyloid origin, evolution and maturation, A??tau interactions and pathogenesis both ex vivo and in vivo.

Aslund, Andreas; Sigurdson, Christina J.; Klingstedt, Therese; Grathwohl, Stefan; Bolmont, Tristan; Dickstein, Dara L.; Glimsdal, Eirik; Prokop, Stefan; Lindgren, Mikael; Konradsson, Peter; Holtzman, David M.; Hof, Patrick R.; Heppner, Frank L.; Gandy, Samuel; Jucker, Mathias; Aguzzi, Adriano; Hammarstrom, Per; Nilsson, K. Peter R.

2010-01-01

336

Accuracy of a simple method for deriving the presampled modulation transfer function of a digital radiographic system from an edge image.  

PubMed

Several methods for accurately deriving the presampled modulation transfer function (MTF) of a pixelated detector from the image of a slightly slanted edge have been described in the literature. In this paper we report on a simple variant of the edge method that produces sufficiently accurate MTF values for frequencies up to the Nyquist frequency limit of the detector with little effort in edge alignment and computation. The oversampled ESF is constructed in a very simple manner by rearranging the pixel data of N consecutive lines corresponding to a lateral shift of the edge by one pixel. A regular subsampling pitch is assumed for the oversampled ESF, which is given by the original pixel sampling distance divided by the integer number N. This allows the original data to be used for further computational analysis (differentiation and Fourier transform) without data preprocessing. Since the number of lines leading to an edge shift by one pixel generally is a fractional number rather than an integer, a systematic error may be introduced into the presampled MTF. Simulations and theoretical investigations show that this error is proportional to 1/N and increases with spatial frequency. For all frequencies up to the Nyquist limit, the relative error delta MTF/MTF is smaller than 1/(2N). It can thus be kept below a given threshold by suitably selecting N, which furnishes a certain maximum edge angle. The method is especially useful for applications where the presampled MTF is needed only for frequencies up to the Nyquist frequency limit, such as the determination of the detective quantum efficiency (DQE). PMID:14528954

Buhr, Egbert; Günther-Kohfahl, Susanne; Neitzel, Ulrich

2003-09-01

337

Analysis of the influences of uncertainties in input variables on the outcomes of the Heliosat-2 method  

Microsoft Academic Search

The Heliosat-2 method, which employs satellite images to assess solar irradiance at ground level, is one of the most accurate among the available operational methods. Its input variables have uncertainties which impact on the final result. The General Law of Uncertainty Propagation is employed to analyze the impact of these uncertainties on a single pixel with Meteosat-7 inputs in various

B. Espinar; L. Ramírez; J. Polo; L. F. Zarzalejo; L. Wald

2009-01-01

338

Analysis of MODIS snow cover time series over the alpine regions as input for hydrological modeling  

NASA Astrophysics Data System (ADS)

Snow extent and relative physical properties are key parameters in hydrology, weather forecast and hazard warning as well as in climatological models. Satellite sensors offer a unique advantage in monitoring snow cover due to their temporal and spatial synoptic view. The Moderate Resolution Imaging Spectrometer (MODIS) from NASA is especially useful for this purpose due to its high frequency. However, in order to evaluate the role of snow on the water cycle of a catchment such as runoff generation due to snowmelt, remote sensing data need to be assimilated in hydrological models. This study presents a comparison on a multi-temporal basis between snow cover data derived from (1) MODIS images, (2) LANDSAT images, and (3) predictions by the hydrological model GEOtop [1,3]. The test area is located in the catchment of the Matscher Valley (South Tyrol, Northern Italy). The snow cover maps derived from MODIS-images are obtained using a newly developed algorithm taking into account the specific requirements of mountain regions with a focus on the Alps [2]. This algorithm requires the standard MODIS-products MOD09 and MOD02 as input data and generates snow cover maps at a spatial resolution of 250 m. The final output is a combination of MODIS AQUA and MODIS TERRA snow cover maps, thus reducing the presence of cloudy pixels and no-data-values due to topography. By using these maps, daily time series starting from the winter season (November - May) 2002 till 2008/2009 have been created. Along with snow maps from MODIS images, also some snow cover maps derived from LANDSAT images have been used. Due to their high resolution (< 30 m) they have been considered as an evaluation tool. The snow cover maps are then compared with the hydrological GEOtop model outputs. The main objectives of this work are: 1. Evaluation of the MODIS snow cover algorithm using LANDSAT data 2. Investigation of snow cover, and snow cover duration for the area of interest for South Tyrol 3. Derivation and interpretation of the snow line for the seven winter seasons 4. An evaluation of the model outputs in order to determine the situations in which the remotely sensed data can be used to improve the model prediction of snow coverage and related variables References [1] Rigon R., Bertoldi G. and Over T.M. 2006. GEOtop: A Distributed Hydrological Model with Coupled Water and Energy Budgets, Journal of Hydrometeorology, 7: 371-388. [2] Rastner P., Irsara L., Schellenberger T., Della Chiesa S., Bertoldi G., Endrizzi S., Notarnicola C., Steurer C., Zebisch M. 2009. Monitoraggio del manto nevoso in aree alpine con dati MODIS multi-temporali e modelli idrologici, 13th ASITA National Conference, 1-4.12.2009, Bari, Italy. [3] Zanotti F., Endrizzi S., Bertoldi G. and Rigon R. 2004. The GEOtop snow module. Hydrological Processes, 18: 3667-3679. DOI:10.1002/hyp.5794.

Notarnicola, Claudia; Rastner, Philipp; Irsara, Luca; Moelg, Nico; Bertoldi, Giacomo; Dalla Chiesa, Stefano; Endrizzi, Stefano; Zebisch, Marc

2010-05-01

339

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

340

Image Registration Techniques in Nuclear Medicine Imaging  

Microsoft Academic Search

Nuclear medicine has a long tradition of incorporating quantitative analysis in its diagnostic procedures. Until recently, the analysis was based on radionuclide images as the sole input although the importance of the complementary information available from other modalities or from earlier scans has long been recognized. Indeed, qualitative correlation between images, based on anatomical expertise, has always been part of

B. F. Hutton; M. Braun; P. Slomka

341

Input functions for 6-[fluorine-18]Fluorodopa quantitation in parkinsonism: Comparative studies and clinical correlations  

SciTech Connect

PET has been used to quantify striatal 6-[{sup 18}F]fluro-L-dopa (FDOPA) uptake as a measure of presynaptic dopaminergic function. Striatal FDOPA uptake rate constants (K{sub 1}) can be calculated using dynamic PET imaging with measurements of the plasma FDOPA input function determined either directly or by several estimation procedures. The authors assessed the comparative clinical utility of these methods by calculating the striato-occipital ratio (SOR) and striatal K{sub 1} values in 12 patients with mild to moderate PD and 12 age-matched normal volunteers. The plasma FDOPA time-activity curve (K{sub 1}{sup FD}); the plasma {sup 18}F time-activity curve (K{sub i}{sup P}); the occipital time-activity curve (K{sub i}{sup OCC}); and a simplified population-derived FDOPA input function (K{sub i}{sup EFD}) were used to calculate striatal K{sub i}. Mean values for all striatal K{sub i} estimates and SOR were significantly lower in the PD group. Although all measured parameters discriminated PD patients with normals, K{sub i}{sup FD} and K{sub i}{sup EFD} provided the best between-group separation. K{sub i}{sup FD}, K{sub i}{sup EFD}, and K{sub i}{sup OCC} measures correlated significantly with quantitative disease severity ratings, although K{sub i}{sup FD} predicted quantitative clinical disability most accurately. These results suggest that K{sub i}{sup FD} may be an optimal marker of the parkinsonian disease process. K{sub i}{sup EFD} may be a useful alternative to K{sub i}{sup FD} for most clinical research applications. 40 refs., 4 figs., 7 tabs.

Takikawa, S.; Dhawan, V.; Chaly, T.; Robeson, W.; Dahl, R.; Zanzi, I.; Mandel, F.; Spetsieris, P.; Eidelberg, D. [North Shore Univ. Hospital/Cornell Univ., Medical College, Manhasset, NY (United States)

1994-06-01

342

Automatic pH Control and Soluble and Insoluble Substrate Input for Continuous Culture of Rumen Microorganisms  

PubMed Central

An artifical rumen continuous culture with pH control, automated input of water-soluble and water-insoluble substrates, controlled mixing of contents, and a collection system for gas is described. Images

Slyter, Leonard L.

1975-01-01

343

Advances in high-resolution image simulation  

SciTech Connect

Continuing advances in hardware and software have improved both the speed and the range of computations that can be made to simulate high resolution electron microscope (HREM) images from various structures. Use of image display systems and array processors have made the image simulation procedure much more interactive while laser printers provide a fast high-quality hard copy output. Use of array processors has enabled the rewriting of electron scattering algorithms to include convergence effects (previously only considered after the scattered electron beams had emerged from the specimen) and upper-layer-line effects. With an array processor it is faster to compute effects of spatial and temporal coherence in real space, rather than use approximation solutions derived from series expansion in reciprocal space. With a frame buffer and suitable software the use has the facility to change parameters and view the results of the change almost immediately. Selected images can then be directed to hard copy output, in contrast with batch methods where series of hard copy images are produced and then selected from. Given a microdensitometer for input of experimental images from plates, or a video camera attached to the electron microscope and a frame buffer, split screen comparisons between experimental and computed images are possible, including independent control of image contrast, magnification and orientation. 23 refs., 19 figs., 2 tabs.

O'Keefe, M.A.; Kilaas, R.

1988-09-01

344

Vector ARMAX modeling approach in multi-input modal analysis  

NASA Astrophysics Data System (ADS)

This paper analyses multivariate time series using a parametric approach for the purpose of identification of modal parameters of mechanical structures. Because of computer capacity the multi-input/multi-output (MIMO) data were treated with the multi-input/single-output (MISO) consecutively. By noting that some of the modal parameters must have global characteristics regardless of measurement locations in theory, a MIMO modeling approach is taken to analyse a set of multiple-random excitation/multiple response measurements. The MISO approach is also applied to the same data and the results obtained by the two methods are compared. Two specific regression models for the MIMO and MISO approach are derived from the vector Autoregressive Moving Average model with exogenous variables (ARMAX) and the least squares method is applied iteratively for the parameter estimation. The modal parameters are derived from the parameters of the vector ARMAX based upon the principle of impulse response invariance. The procedures are used to analyse a set of simulation data of a three degree of freedom system.

Park, Byeong-Ho; Kim, Kwang-Joon

1989-10-01

345

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

346

Image-based modeling and photo editing  

Microsoft Academic Search

We present an image-based modeling and editing system that takes a single photo as input. We represent a scene as a layered collection of depth images, where each pixel encodes both color and depth. Starting from an input image, we employ a suite of user-assisted techniques, based on a painting metaphor, to assign depths and extract layers. We introduce two

Byong Mok Oh; Max Chen; Julie Dorsey; Frédo Durand

2001-01-01

347

Replenishment of magma chambers by light inputs  

NASA Astrophysics Data System (ADS)

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 ? denotes the uniform density of the resident magma and ? — ?? that of the input, the situation is described by the reduced gravity g' = g??/?, the volume flux Q, and the viscosities of the resident and input magmas ?e and ?i, respectively. The (nondimensional) Reynolds numbers, Ree = (g'Q3)1/5/?e and Rei = (g'Q3)1/5/?i and chamber geometry then completely specify the system. For sufficiently low values of the two Reynolds numbers (each less than approximately 10), the input rises as a laminar conduit. For larger values of the Reynolds numbers, the conduit may break down and exhibit either a varicose or a meander instability and entrain some resident magma. At still larger Reynolds numbers, the flow will become quite unsteady and finally turbulent. The values of the Reynolds numbers at which these transitions occur have been documented by a series of experiments with water, glycerine, and corn syrup. If the input rises as a turbulent plume, significant entrainment of the resident magma can take place. The final spatial distribution of the mixed magma depends on the geometry of the chamber. If the chamber is much wider than it is high, the mixed magma forms a compositionally stratified region between the roof and a sharp front above uncontaminated magma. In the other geometrical extreme, the input magma is mixed with almost all of the resident magma. If the density of the resident magma is already stratified, the input plume may penetrate only part way into the chamber, even though its initial density is less than that of the lowest density resident magma. The plume will then intrude horizontally and form a hybrid layer at an intermediate depth. This provides a mechanism for preventing even primitive basaltic magmas of minimum density from erupting at the surface. By conducting an experiment using aqueous solutions, we show that entrainment can lead to crystallization of the magma in the input plume by making it locally supersaturated. All these effects are discussed and illustrated by photographs of laboratory experiments.

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

1986-05-01

348

Three-input majority logic gate and multiple input logic circuit based on DNA strand displacement.  

PubMed

In biomolecular programming, the properties of biomolecules such as proteins and nucleic acids are harnessed for computational purposes. The field has gained considerable attention due to the possibility of exploiting the massive parallelism that is inherent in natural systems to solve computational problems. DNA has already been used to build complex molecular circuits, where the basic building blocks are logic gates that produce single outputs from one or more logical inputs. We designed and experimentally realized a three-input majority gate based on DNA strand displacement. One of the key features of a three-input majority gate is that the three inputs have equal priority, and the output will be true if any of the two inputs are true. Our design consists of a central, circular DNA strand with three unique domains between which are identical joint sequences. Before inputs are introduced to the system, each domain and half of each joint is protected by one complementary ssDNA that displays a toehold for subsequent displacement by the corresponding input. With this design the relationship between any two domains is analogous to the relationship between inputs in a majority gate. Displacing two or more of the protection strands will expose at least one complete joint and return a true output; displacing none or only one of the protection strands will not expose a complete joint and will return a false output. Further, we designed and realized a complex five-input logic gate based on the majority gate described here. By controlling two of the five inputs the complex gate can realize every combination of OR and AND gates of the other three inputs. PMID:23710909

Li, Wei; Yang, Yang; Yan, Hao; Liu, Yan

2013-05-30

349

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

350

Computer-Aided Diagnosis in Breast MRI: Do Adjunct Features Derived from T 2-weighted Images Improve Classification of Breast Masses?  

Microsoft Academic Search

In the field of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) of breast cancer, current research efforts in computer-aided diagnosis (CADx) are mainly focused on the temporal series of T 1-weighted images acquired during uptake of a contrast agent, processing morphological and kinetic information. Although static T 2-weighted images are usually part of DCE-MRI protocols, they are seldom used in CADx

Willem van Aalst; Thorsten Twellmann; Hans Buurman; Frans A. Gerritsen; Bart M. Ter Haar Romeny

2008-01-01

351

Computer-Aided Diagnosis in Breast MRI: Do Adjunct Features Derived from T2-weighted Images Improve Classification of Breast Masses?  

Microsoft Academic Search

In the field of dynamic contrast-enhanced magnetic reso- nance imaging (DCE-MRI) of breast cancer, current research efforts in computer-aided diagnosis (CADx) are mainly focused on the temporal series of T1-weighted images acquired during uptake of a contrast agent, processing morphological and kinetic information. Although static T2- weighted images are usually part of DCE-MRI protocols, they are sel- dom used in

Willem Van Aalst; Thorsten Twellmann; Hans Buurman; Frans A. Gerritsen; Bart M. Ter Haar Romeny

2008-01-01

352

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).

2012-01-01

353

Scratch input: creating large, inexpensive, unpowered and mobile finger input surfaces  

Microsoft Academic Search

We present Scratch Input, an acoustic-based input tech- nique that relies on the unique sound produced when a fin- gernail is dragged over the surface of a textured material, such as wood, fabric, or wall paint. We employ a simple sensor that can be easily coupled with existing surfaces, such as walls and tables, turning them into large, unpow- ered

Chris Harrison; Scott E. Hudson

2008-01-01

354

Image registration and atlas-based segmentation of cardiac outflow velocity profiles.  

PubMed

Cardiovascular disease is the leading cause of death worldwide and for this reason computer-based diagnosis of cardiac diseases is a very important task. In this article, a method for segmentation of aortic outflow velocity profiles from cardiac Doppler ultrasound images is presented. The proposed method is based on the statistical image atlas derived from ultrasound images of healthy volunteers. The ultrasound image segmentation is done by registration of the input image to the atlas, followed by a propagation of the segmentation result from the atlas onto the input image. In the registration process, the normalized mutual information is used as an image similarity measure, while optimization is performed using a multiresolution gradient ascent method. The registration method is evaluated using an in-silico phantom, real data from 30 volunteers, and an inverse consistency test. The segmentation method is evaluated using 59 images from healthy volunteers and 89 images from patients, and using cardiac parameters extracted from the segmented image. Experimental validation is conducted using a set of healthy volunteers and patients and has shown excellent results. Cardiac parameter segmentation evaluation showed that the variability of the automated segmentation relative to the manual is comparable to the intra-observer variability. The proposed method is useful for computer aided diagnosis and extraction of cardiac parameters. PMID:21156328

Kalini?, Hrvoje; Lon?ari?, Sven; Cikeš, Maja; Mili?i?, Davor; Bijnens, Bart

2010-12-14

355

7 CFR 3431.4 - Solicitation of stakeholder input.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Solicitation of stakeholder input. 3431.4 Section 3431.4...Situations § 3431.4 Solicitation of stakeholder input. The Secretary will solicit stakeholder input on the process and...

2010-01-01

356

Evaluating capacitive touch input on clothes  

Microsoft Academic Search

Wearable computing and smart clothing have attracted a lot of attention in the last years. For a variety of applications, it can be seen as potential future direction of mobile user interfaces. In this paper, we concentrate on usability and applicability issues concerned with capacitive touch input on clothing. To be able to perform user studies, we built a generic

Paul Holleis; Albrecht Schmidt; Susanna Paasovaara; Arto Puikkonen; Jonna Häkkilä

2008-01-01

357

Responding to Semantically Ill-Formed Input,  

National Technical Information Service (NTIS)

One cause of failure language interfaces is semantic overshoot; this is reflected in input sentences which do not correspond to any semantic pattern in the system, We describe a system which provides helpful feedback in such cases by identifying the seman...

R. Grishman P. Peng

1987-01-01

358

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

359

Treatments of Precipitation Inputs to Hydrologic Models  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hydrological models are used to assess many water resources problems from agricultural use and water quality to engineering issues. The success of these models are dependent on correct parameterization; the most sensitive being the rainfall input time series. These records can come from land-based ...

360

Dual Motion Valve with Single Motion Input.  

National Technical Information Service (NTIS)

A dual motion valve (A) includes two dual motion valve assemblies with a rotary input which allows the benefits of applying both rotary and axial motion to a rotary sealing element with a plurality of ports. The motion of the rotary sealing element during...

R. R. Belew

1985-01-01

361

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

362

Stane: synthesized surfaces for tactile input  

Microsoft Academic Search

Stane is a hand-held interaction device controlled by tactile input: scratching or rubbing textured surfaces and tapping. The system has a range of sensors, including contact micro- phones, capacitive sensing and inertial sensing, and provides audio and vibrotactile feedback. The surface textures vary around the device, providing perceivably different textures to the user. We demonstrate that the vibration signals genera-

Roderick Murray-smith; John Williamson; Stephen Hughes; Torben Quaade

2008-01-01

363

Multiple Input Microcantilever Sensor with Capacitive Readout  

SciTech Connect

A surface-micromachined MEMS process has been used to demonstrate multiple-input chemical sensing using selectively coated cantilever arrays. Combined hydrogen and mercury-vapor detection was achieved with a palm-sized, self-powered module with spread-spectrum telemetry reporting.

Britton, C.L., Jr.; Brown, G.M.; Bryan, W.L.; Clonts, L.G.; DePriest, J.C.; Emergy, M.S.; Ericson, M.N.; Hu, Z.; Jones, R.L.; Moore, M.R.; Oden, P.I.; Rochelle, J.M.; Smith, S.F.; Threatt, T.D.; Thundat, T.; Turner, G.W.; Warmack, R.J.; Wintenberg, A.L.

1999-03-11

364

Investment in Education—Inputs and Incentives  

Microsoft Academic Search

From the point of view of economic development, education is the acquisition of knowledge and skills through experiences from conception onwards over the life cycle that increase productivity broadly defined. Education can occur through, but is not limited to, formal educational activities such as preschool programs, schools, and formal training programs. The proximate determinants of education are experiences or inputs

Jere R. Behrman

2010-01-01

365

Robustness of decoupling with almost redundant inputs  

Microsoft Academic Search

Control design for an ill-conditioned plant is known to be problematic. One reason a plant may be ill-conditioned is that its control inputs may be almost redundant, in the sense that they have an almost identical effect upon the controlled outputs. In this paper we study robustness problems that may occur when a controller that decouples, or partially decouples, the

J. Freudenberg; Rick Middleton

2002-01-01

366

Bioelectric input devices: an example: BIOLINK  

Microsoft Academic Search

As new input devices for interactive systems appear (e.g., eye pointing devices, data gloves, motion detection systems, speech recognition systems), devices based on bioelectric signals are emerging. They are still very few and mainly used for electronic music systems. This development, which have been pioneered by Rosenboom (1976), originates from the desire to control electronic music by biofeedback techniques. For

François Aubin; Jean-Marc Robert

1992-01-01

367

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

368

Dynamically adapting GUIs to diverse input devices  

Microsoft Academic Search

Many of today's desktop applications are designed for use with a pointing device and keyboard. Someone with a dis- ability, or in a unique environment, may not be able to use one or both of these devices. We have developed an approach for automatically modifying desktop applications to accommodate a variety of input alternatives as well as a demonstration implementation,

Scott Carter; Amy Hurst; Jennifer Mankoff; Jack Li

2006-01-01

369

The Texas Input-Output Model, 1972.  

National Technical Information Service (NTIS)

The purpose of the report is to revise and update the 1967 Input-Output Model to 1972, the latest year for which a complete economic census is available. This model can be used as a: (1) source of information about the Texas economy, (2) tool to evaluate ...

1978-01-01

370

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

371

Input variable selection for median flood regionalization  

NASA Astrophysics Data System (ADS)

Flood estimation for ungauged catchments is a challenging task for hydrologists. A modern geographical information system is able to extract a large number of catchment characteristics as input variables for regionalization analysis. Effective and efficient selection of the best input variables is urgently needed in this field. This paper explores a new methodology for selecting the best input variable combination on the basis of the gamma test and leave-one-out cross validation (LOOCV) to estimate the median annual maximum flow (as an index flood). Since the gamma test is capable of efficiently calculating the output variance on the basis of the input without the need to select a model structure type, more effective regionalization models could be developed because there is no need to define an a priori model structure. A case study from 20 catchments in southwest England has been used to illustrate and validate the proposed scheme. It has been found that the gamma test is able to narrow down the search options to be further explored by the LOOCV. The best formula from this approach outperforms the conventional approaches based on cross validation, data filtering with Spearman's rank correlation matrix, and corrected Akaike information criterion. In addition, the developed formula is significantly more accurate than the existing equation used in the Flood Estimation Handbook.

Wan Jaafar, W. Z.; Liu, J.; Han, D.

2011-07-01

372

JIAWG Input/Output System (JIOS).  

National Technical Information Service (NTIS)

The JIAWG Input/Output System (JIOS) provides the software/hardware Interface for Built-In-Test and l/O provided via the PI-Bus and TM-Bus for the JIAWG 16-bit Common Modules. This paper describes the need for JIOS, the functionality of the JIOS, concerns...

C. Roark J. Newport

1990-01-01

373

Repeat on input for data flow computers  

DOEpatents

A processing node for a data flow parallel processing computer is activated by an input token from the system. The token or the stored information in the node includes information to cause the node to repeat a specified sequence of operations upon initiation by the token, thereby increasing the efficiency system for some computing operations.

Grafe, V.G.; Hoch, J.E.

1989-12-27

374

Identification of Multi-Input Biological Systems  

Microsoft Academic Search

The Wiener theory of nonlinear system identification is extended to multi-input-output systems and experimentally applied. The experimental applicability of the method is discussed with regard to biological systems. It is shown that the method is well suited for the treatment of the idiosyncratic features of such systems: nonlinearities, short lifetimes of experimental preparations, and high noise content. A preliminary analysis

Panos Z. Marmarelis; Ken-Ichi Naka

1974-01-01

375

A hydro-optical model for deriving water quality variables from satellite images (HydroSat): A case study of the Nile River demonstrating the future Sentinel-2 capabilities  

NASA Astrophysics Data System (ADS)

This paper describes a hydro-optical model for deriving water quality variables from satellite images, hereafter HydroSat. HydroSat corrects images for atmospheric interferences and simultaneously retrieves water quality variables. An application of HydroSat to Landsat Enhanced Thematic Mapper (ETM) observations over the Rosetta Branch of the Nile River demonstrates that reliable estimates of water quality are obtained. For example, the impact of the many water inlets along the Rosetta on the water quality can be very well identified. Quantitatively, the accuracy of the derived products is assessed via comparison with the output of a validated water quality process model for the Rosetta Branch. This matchup between the HydroSat and process model's output results in determination coefficients, R2s, larger than 0.6 for all derived water quality variables. It should be noted that derivation of water quality variables using HydroSat does not rely on any tuning parameters. Hence, the successful application of HydroSat to Landsat-ETM data could also be seen as a demonstration of the future Sentinel-2 capabilities for mapping water quality over rivers.

Salama, Mhd. Suhyb; Radwan, Mona; van der Velde, Rogier

376

Input permutation method to detect active voxels in fMRI study.  

PubMed

Correctly identifying voxels or regions of interest (ROI) that actively respond to a given stimulus is often an important objective/step in many functional magnetic resonance imaging (fMRI) studies. In this article, we study a nonparametric method to detect active voxels, which makes minimal assumption about the distribution of blood oxygen level-dependent (BOLD) signals. Our proposal has several interesting features. It uses time lagged correlation to take into account the delay in response to the stimulus, due to hemodynamic variations. We introduce an input permutation method (IPM), a type of block permutation method, to approximate the null distribution of the test statistic. Also, we propose to pool the permutation-derived statistics of preselected voxels for a better approximation to the null distribution. Finally, we control multiple testing error rate using the local false discovery rate (FDR) by Efron [Correlation and large-scale simultaneous hypothesis testing. J Am Stat Assoc 102 (2007) 93-103] and Park et al. [Estimation of empirical null using a mixture of normals and its use in local false discovery rate. Comput Stat Data Anal 55 (2011) 2421-2432] to select the active voxels. PMID:22819177

Lee, Sang H; Lim, Johan; Park, DoHwan; Biswal, Bharat B; Petkova, Eva

2012-07-20

377

Polar Mesospheric Cloud properties derived from the Cloud Imaging and Particle Size Experiment on the Aeronomy of Ice in the Mesosphere Mission  

Microsoft Academic Search

The Cloud Imaging and Particle Size Experiment (CIPS) is a four-camera nadir pointing imager with a bandpass centered at 265 nm and a field of view of 80 by 120 degrees. CIPS observes Polar Mesospheric Clouds (PMCs) against the sunlit Rayleigh scattered background. The observations cover five PMC seasons, three in the North (2007, 2008, and 2009) and two in

D. W. Rusch; G. E. Thomas; W. E. McClintock; A. W. Merkel; J. D. Lumpe; S. Benze; S. Bailey; C. E. Randall; J. M. Russell

2009-01-01

378

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

379

Shifts in allochthonous input and autochthonous production in streams along an agricultural land-use gradient  

Microsoft Academic Search

Relative contributions of allochthonous inputs and autochthonous production vary depending on terrestrial land use and biome.\\u000a Terrestrially derived organic matter and in-stream primary production were measured in 12 headwater streams along an agricultural\\u000a land-use gradient. Streams were examined to see how carbon (C) supply shifts from forested streams receiving primarily terrestrially\\u000a derived C to agricultural streams, which may rely primarily

Elizabeth M. HagenMatthew; Matthew E. McTammany; Jackson R. WebsterErnest; Ernest F. Benfield

2010-01-01

380

Evidence for Oceanic/Continental Climate Linkages During Freshwater Inputs to the Gulf of Mexico  

NASA Astrophysics Data System (ADS)

Understanding the linkage between oceanic and continental responses to millennial-scale climate variability can provide insight into the mechanisms controlling abrupt global climate change, however there are few marine depositional systems where these linkages can be studied simultaneously. Here we present new evidence for freshwater input (Laurentide Ice Sheet (LIS) meltwater versus precipitation?) to the northern Gulf of Mexico from 28-45 ka (within Marine Isotope Stage 3), and draw linkages to continental climate using organic geochemical proxies. A 32-m laminated sediment core (MD02-2551) from the anaerobic Orca Basin was collected aboard the R/V Marion Dufresne in July 2002 as part of the IMAGES program. Radiocarbon dates suggest that the average sedimentation rate is >50 cm/1000 years during this interval, allowing for 40-year resolution sampling at 2-cm intervals. Paired ? 18O and Mg/Ca data on the planktic foraminifer Globigerinoides ruber are used to separate changes in Mg-derived sea-surface temperature (SST) and the oxygen isotopic composition of seawater, which can be interpreted in terms of salinity. Three large negative excursions in ? 18Osw (<0.5 \\permil), each lasting ~3 ka, exist in the record. Two of these excursions may correlate with Heinrich events 3 and 4, but show no clear relationship to Dansgaard-Oeschger warmings. ? 18Osw excursions have significant ramifications for Gulf of Mexico salinity, which can be constrained using two freshwater end members: the current Mississippi River (MR) value of -7 \\permil and an LIS value of -30 \\permil. Use of the MR end-member would require extraordinarily large floods and changes in salinity of 5-6 psu, whereas use of the LIS end-member results in a salinity decrease of 2-3 psu. Preliminary results of analyses of organic biomarkers preserved in the Orca Basin sediments suggest that the freshwater events are dominated by terrigenous organic matter, but are also associated with an increase in marine-derived algal inputs, suggesting that changes in the nutrient flux to the Gulf of Mexico from the North American continent may support marine production. Molecular carbon and hydrogen isotopic components of biomarkers will be used to evaluate shifts in continental climate through analyses of vegetation (? 13C; C3 vs C4 plants) and source water (? D) changes during large salinity excursions observed in the Gulf of Mexico.

Hill, H. W.; Flower, B. P.; Hollander, D. J.; Quinn, T. M.

2004-12-01

381

A Novel Color Transfer Algorithm for Image Sequences  

Microsoft Academic Search

This paper presents a novel image sequence color transfer algorithm (ISCT). It is able to render an image sequence with color characteristics borrowed from three user-given target images. The input of this algorithm consists of a single input image (I1) and three target images (T1, T2, T3). The output of the algorithm is an image sequence {Si} with N images

Chung-ming Wang; Yao-hsien Huang

2004-01-01

382

Synthesis and biological evaluation of a novel (99m)Tc labeled 2-nitroimidazole derivative as a potential agent for imaging tumor hypoxia.  

PubMed

Tumor hypoxia plays a major role in reducing the efficacy of therapeutic modalities like chemotherapy and radiation therapy in combating cancer. In order to target hypoxic tissues, a tripeptide ligand having a 2-nitroimidazole moiety, as a bioreductive species, was synthesized. The latter was radiolabeled with (99m)Tc for imaging hypoxic regions of tumors and was characterized by means of its rhenium analogue. The biodistribution and scintigraphic image of the corresponding (99m)Tc-complex showed accumulation in tumor and these results suggest that it could be a marker for imaging tumor hypoxia. PMID:23726027

Joyard, Yoann; Le Joncour, Vadim; Castel, Hélène; Diouf, Chérif Bounana; Bischoff, Laurent; Papamicaël, Cyril; Levacher, Vincent; Vera, Pierre; Bohn, Pierre

2013-05-16

383

Sniffing controls an adaptive filter of sensory input to the olfactory bulb  

Microsoft Academic Search

Most sensory stimuli are actively sampled, yet the role of sampling behavior in shaping sensory codes is poorly understood. Mammals sample odors by sniffing, a complex behavior that controls odorant access to receptor neurons. Whether sniffing shapes the neural code for odors remains unclear. We addressed this question by imaging receptor input to the olfactory bulb of awake rats performing

Justus V Verhagen; Daniel W Wesson; Theoden I Netoff; John A White; Matt Wachowiak

2007-01-01

384

Multimodal interfaces with voice and gesture input  

SciTech Connect

The modalities of speech and gesture have different strengths and weaknesses, but combined they create synergy where each modality corrects the weaknesses of the other. We believe that a multimodal system such a one interwining speech and gesture must start from a different foundation than ones which are based solely on pen input. In order to provide a basis for the design of a speech and gesture system, we have examined the research in other disciplines such as anthropology and linguistics. The result of this investigation was a taxonomy that gave us material for the incorporation of gestures whose meanings are largely transparent to the users. This study describes the taxonomy and gives examples of applications to pen input systems.

Milota, A.D.; Blattner, M.M.

1995-07-20

385

Entanglement distillation from Gaussian input states  

NASA Astrophysics Data System (ADS)

Entanglement distillation is an essential protocol for long-distance quantum communications, typically for extending the range of quantum key distribution. In the field of continuous variable quantum information processing, quantum as well as classical information is encoded in the light field quadratures, often in the form of Gaussian states. However, distillation from Gaussian input states has not yet been accomplished. It is made difficult by a prominent no-go theorem stating that no Gaussian operation can distill Gaussian states. Here we demonstrate, for the first time, such distillation from Gaussian input states, realized by the implementation of non-Gaussian operations. By subtracting one or two photons, a large gain of entanglement was observed. For two photons, Gaussian-like entanglement was also improved. Other than quantum key distribution, this distilled entanglement can also be used for downstream applications such as high-fidelity quantum teleportation and a loophole-free Bell test.

Takahashi, Hiroki; Neergaard-Nielsen, Jonas S.; Takeuchi, Makoto; Takeoka, Masahiro; Hayasaka, Kazuhiro; Furusawa, Akira; Sasaki, Masahide

2010-03-01

386

Dust input from AGB stars in the Large Magellanic Cloud  

NASA Astrophysics Data System (ADS)

Aims: The dust-forming population of AGB stars and their input to the interstellar dust budget of the Large Magellanic Cloud (LMC) are studied with evolutionary dust models with the main goals (1) to investigate how the amount and composition of dust from AGB stars vary over the galactic history; (2) to characterise the mass and metallicity distribution of the present population of AGB stars; (3) to quantify the contribution of AGB stars of different mass and metallicity to the present stardust population in the interstellar medium (ISM). Methods: We used models of the stardust lifecycle in the ISM developed and tested for the solar neighbourhood. The first global spatially resolved reconstruction of the star formation history of the LMC from the Magellanic Clouds Photometric Survey was employed to calculate the stellar populations in the LMC. Results: The dust input from AGB stars is dominated by carbon grains from stars with masses ?4 M? almost during the entire history of the LMC. The production of silicate, silicon carbide, and iron dust is delayed until the ISM is enriched to about half the present metallicity in the LMC. For the first time, theoretically calculated dust production rates of AGB stars are compared with those derived from infrared observations of AGB stars for the entire galaxy. We find good agreement within scatter of various observational estimates. We show that the majority of silicate and iron grains in the present stardust population originate from a small population of intermediate-mass stars consisting of only ?4% of the total number of stars, whereas in the solar neighbourhood they originate from low-mass stars. With models of the lifecycle of stardust grains in the ISM we confirm the strong discrepancy between dust input from stars and the existing interstellar dust mass in the LMC reported previously.

Zhukovska, S.; Henning, T.

2013-07-01

387

Using 232Th to monitor dissolved and total detrital inputs to the ocean  

Microsoft Academic Search

This study uses long lived thorium isotopes as a tracer for both total and dissolved detrital inputs to seawater over time. Th-232 in seawater is derived exclusively from detritus, and its presence in the dissolved phase results from partial dissolution of this material. 230Th is produced in situ at a predictable rate by the decay of uranium, and its subsequent

L. F. Robinson; T. L. Noble; J. F. McManus

2007-01-01

388

Position control of ultrasonic motors using two-control inputs H? controller  

Microsoft Academic Search

The ultrasonic motor has nonlinearity characteristics, which varies with driving conditions associated the variations of temperature and applied load torque of USM. The nonlinearity characteristics for actuators are problem in accurate position control. To improve the control performance of the ultrasonic motor, we apply two-control inputs H? controller for position control of the USM. Applying an H? methodology we derive

Tomonobu Senjyu; T. Yoshida; N. Urasaki; K. Uezato; T. Funabashi; H. Sekine; S. K. Panda

2003-01-01

389

AN ANALYSIS OF THE POLE PLACEMENT PROBLEM II. THE MULTI-INPUT CASE  

Microsoft Academic Search

For the solution of the multi-input pole placement problem we derive explicit formulas for the sub- space from which the feedback gain matrix can be chosen and for the feedback gain as well as the eigenvector matrix of the closed-loop system. We discuss which Jordan structures can be assigned and also when diagonalizability can be achieved. Based on these formulas

VOLKER MEHRMANN; HONGGUO XU

390

An LMI-based approach to critical control system design for rate-limited exogenous inputs  

Microsoft Academic Search

This paper considers a linear matrix inequality approach to the design of critical control systems for rate-limited exogenous inputs. The sufficient condition for ensuring the critical requirement is derived from the exponential convergence condition of the unit step response. By changing the variables, it is transformed into the set of BMI and LMI conditions. The problem amounts to a convex

Takahiko Ono; Tadashi Ishihara; Hikaru Inooka

2002-01-01

391

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

392

Input impedance of closed-loop PWM buck-boost DC-DC converter for CCM  

Microsoft Academic Search

The small-signal closed-loop impedance of the PWM buck-boost DC-DC converter is derived for continuous conduction mode (CCM), taking into account all parasitic resistances. The plots of the closed-loop input impedance are shown versus frequency for three values of the duty cycle

M. K. Kazimierczuk

1995-01-01

393

The Dynamic Response or PWM DC-DC Conv~rtc..s with Input Filters  

Microsoft Academic Search

The paper develops computer aided procedures for the analysis and design or input filters or PWM DC-DC converters operating in voltage or current mode. The proposed methodology is based on the Switched Inductor Model (SIM) which is an equivalent circuit approach for modelling and simulation of switch mode systems. The method is compatible with all versions of SPICE derived electronic

Sam Ben

394

An analysis of the acoustic input impedance of the ear.  

PubMed

Ear canal acoustics was examined using a one-dimensional lossy transmission line with a distributed load impedance to model the ear. The acoustic input impedance of the ear was derived from sound pressure measurements in the ear canal of healthy human ears. A nonlinear least squares fit of the model to data generated estimates for ear canal radius, ear canal length, and quantified the resistance that would produce transmission losses. Derivation of ear canal radius has application to quantifying the impedance mismatch at the eardrum between the ear canal and the middle ear. The length of the ear canal was found, in general, to be longer than the length derived from the one-quarter wavelength standing wave frequency, consistent with the middle ear being mass-controlled at the standing wave frequency. Viscothermal losses in the ear canal, in some cases, may exceed that attributable to a smooth rigid wall. Resistance in the middle ear was found to contribute significantly to the total resistance. In effect, this analysis "reverse engineers" physical parameters of the ear from sound pressure measurements in the ear canal. PMID:23917695

Withnell, Robert H; Gowdy, Lauren E

2013-08-06

395

Generalized Input-Output Inequality Systems  

SciTech Connect

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

Liu Yingfan [Department of Mathematics, Nanjing University of Post and Telecommunications, Nanjing 210009 (China)], E-mail: yingfanliu@hotmail.com; Zhang Qinghong [Department of Mathematics and Computer Science, Northern Michigan University, Marquette, MI 49855 (United States)], E-mail: qzhang@nmu.edu

2006-09-15

396

Two pointer input for 3D interaction  

Microsoft Academic Search

We explore a range of techniques that use two hands to control two independent cursors to perform operations in 3D desktop applications. Based on research results in 2D applications , we believe that two-handed input provides the potential for creating more efficient and more fluid interfaces, especiall y for tasks that are context-sensitive or that have many degre es of

Robert C. Zeleznik; Andrew S. Forsberg; Paul S. Strauss

1997-01-01

397

Spatial frequency domain image processing for biometric recognition  

Microsoft Academic Search

Biometric recognition refers to the process of matching an input biometric to stored biometric information. In particular, biometric verification refers to matching the live biometric input from an individual to the stored biometric template about that individual. Examples of biometrics include face images, fingerprint images, iris images, retinal scans, etc. Thus, image processing techniques prove useful in the biometric recognition.

B. V. K. Vijaya Kumar; Chunyan Xie; Marios Savvides; Krithika Venkataramani

2002-01-01

398

Molecular structure input on the web  

PubMed Central

A molecule editor, that is program for input and editing of molecules, is an indispensable part of every cheminformatics or molecular processing system. This review focuses on a special type of molecule editors, namely those that are used for molecule structure input on the web. Scientific computing is now moving more and more in the direction of web services and cloud computing, with servers scattered all around the Internet. Thus a web browser has become the universal scientific user interface, and a tool to edit molecules directly within the web browser is essential. The review covers a history of web-based structure input, starting with simple text entry boxes and early molecule editors based on clickable maps, before moving to the current situation dominated by Java applets. One typical example - the popular JME Molecule Editor - will be described in more detail. Modern Ajax server-side molecule editors are also presented. And finally, the possible future direction of web-based molecule editing, based on technologies like JavaScript and Flash, is discussed.

2010-01-01

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

400

Masticator space abscess derived from odontogenic infection: imaging manifestation and pathways of extension depicted by CT and MR in 30 patients  

Microsoft Academic Search

Propagation of odontogenic masticator space abscesses is insufficiently understood. The purpose was to analyse pathways of\\u000a spread in 30 patients with odontogenic masticator space abscess. The imaging findings in 30 patients (CT in 30, MR in 16 patients)\\u000a were retrospectively analysed. CT and MR imaging depicted a masticator space abscess within: medial pterygoid muscle in 13\\u000a patients (43.3%), lateral masseter

B. Schuknecht; G. Stergiou; K. Graetz

2008-01-01

401

Contrast-guided image interpolation.  

PubMed

In this paper a contrast-guided image interpolation method is proposed that incorporates contrast information into the image interpolation process. Given the image under interpolation, four binary contrast-guided decision maps (CDMs) are generated and used to guide the interpolation filtering through two sequential stages: 1) the 45 (°) and 135 (°) CDMs for interpolating the diagonal pixels and 2) the 0 (°) and 90 (°) CDMs for interpolating the row and column pixels. After applying edge detection to the input image, the generation of a CDM lies in evaluating those nearby non-edge pixels of each detected edge for re-classifying them possibly as edge pixels. This decision is realized by solving two generalized diffusion equations over the computed directional variation (DV) fields using a derived numerical approach to diffuse or spread the contrast boundaries or edges, respectively. The amount of diffusion or spreading is proportional to the amount of local contrast measured at each detected edge. The diffused DV fields are then thresholded for yielding the binary CDMs, respectively. Therefore, the decision bands with variable widths will be created on each CDM. The two CDMs generated in each stage will be exploited as the guidance maps to conduct the interpolation process: for each declared edge pixel on the CDM, a 1-D directional filtering will be applied to estimate its associated to-be-interpolated pixel along the direction as indicated by the respective CDM; otherwise, a 2-D directionless or isotropic filtering will be used instead to estimate the associated missing pixels for each declared non-edge pixel. Extensive simulation results have clearly shown that the proposed contrast-guided image interpolation is superior to other state-of-the-art edge-guided image interpolation methods. In addition, the computational complexity is relatively low when compared with existing methods; hence, it is fairly attractive for real-time image applications. PMID:23846469

Wei, Zhe; Ma, Kai-Kuang

2013-07-03

402

Definition and use of higher-level graphics input tools  

Microsoft Academic Search

A proposal is made for the definition of 'tools', high-level graphics input functions based on the six primitive input classes Clock, Pick, Button, Key, Valuator and Locator. Tools are defined in terms of input expressions, the operands of which are themselves tools, the definition of which may be nested inside this tool. Input expressions are written much like production rules

Jan Van den Bos

1978-01-01

403

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

404

Single image dehazing by multi-scale fusion.  

PubMed

Haze is an atmospheric phenomenon that significantly degrades the visibility of outdoor scenes. This is mainly due to the atmosphere particles that absorb and scatter the light. This paper introduces a novel single image approach that enhances the visibility of such degraded images. Our method is a fusion-based strategy that derives from two original hazy image inputs by applying a white balance and a contrast enhancing procedure. To blend effectively the information of the derived inputs to preserve the regions with good visibility, we filter their important features by computing three measures (weight maps): luminance, chromaticity, and saliency. To minimize artifacts introduced by the weight maps, our approach is designed in a multiscale fashion, using a Laplacian pyramid representation. We are the first to demonstrate the utility and effectiveness of a fusion-based technique for dehazing based on a single degraded image. The method performs in a per-pixel fashion, which is straightforward to implement. The experimental results demonstrate that the method yields results comparative to and even better than the more complex state-of-the-art techniques, having the advantage of being appropriate for real-time applications. PMID:23674449

Ancuti, Codruta Orniana; Ancuti, Cosmin

2013-08-01

405

Multiple-input full bridge dc\\/dc converter  

Microsoft Academic Search

In the renewable power system with two or more sources, the application of multiple-input converter (MIC) instead of several single-input converters can simplify the circuit and reduce the cost. A novel multiple-input full bridge dc\\/dc converter is proposed in this paper. Taking the two inputs as the example, the operation principles and characteristics of the double-input full bridge dc\\/dc converter

Dongsheng Yang; Xinbo Ruan; Yan Li; Fuxin Liu

2009-01-01

406

Input—output modeling of production processes for business management  

Microsoft Academic Search

The input—ouput model is traditionally used for macroeconomic analysis. In this paper, we develop a micro-level input—output process model and demonstrate how it can be used to provide information and analytical support for making business decisions. The input—output process model provides a mathematical description of production processes and the input—output structure of a company or plant. It includes all inputs

Xiannuan Lin; Karen R. Polenske

1998-01-01

407

Nonlinear dimensionality reduction combining MR imaging with non-imaging information.  

PubMed

We propose a framework for the extraction of biomarkers from low-dimensional manifolds representing inter-subject brain variation. Manifold coordinates of each image capture information about structural shape and appearance and, when a phenotype exists, about the subject's clinical state. Our framework incorporates subject meta-information into the manifold learning step. Apart from gender and age, information such as genotype or a derived biomarker is often available in clinical studies and can inform the classification of a query subject. Such information, whether discrete or continuous, is used as an additional input to manifold learning, extending the Laplacian Eigenmap objective function and enriching a similarity measure derived from pairwise image similarities. The biomarkers identified with the proposed method are data-driven in contrast to a priori defined biomarkers derived from, e.g., manual or automated segmentations. They form a unified representation of both the imaging and non-imaging measurements, providing a natural use for data analysis and visualization. We test the method to classify subjects with Alzheimer's Disease (AD), mild cognitive impairment (MCI) and healthy controls enrolled in the ADNI study. Non-imaging metadata used are ApoE genotype, a risk factor associated with AD, and the CSF-concentration of A?(1-42), an established biomarker for AD. In addition, we use hippocampal volume as a derived imaging-biomarker to enrich the learned manifold. Our classification results compare favorably to what has been reported in a recent meta-analysis using established neuroimaging methods on the same database. PMID:22244037

Wolz, Robin; Aljabar, Paul; Hajnal, Joseph V; Lötjönen, Jyrki; Rueckert, Daniel

2011-12-22

408

A comparison of rat SPECT images obtained using (99m)Tc derived from 99Mo produced by an electron accelerator with that from a reactor.  

PubMed

Recent shortages of molybdenum-99 ((99)Mo) 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 (99)Mo from which technetium-99m ((99m)Tc) is extracted. SPECT images of rat anatomy obtained using the accelerator-produced (99m)Tc with those obtained using (99m)Tc from a commercial generator were compared. Disks of (100)Mo were irradiated with x-rays produced by a 35 MeV electron beam to generate about 1110 MBq (30 mCi) of (99)Mo per disk. After target dissolution, a NorthStar ARSII unit was used to separate the (99m)Tc, 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 (99m)Tc from a standard reactor (99)Mo generator. The efficiency of (99)Mo-(99m)Tc separation was typically greater than 90%. This study demonstrated the delivery of (99m)Tc 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 (99m)Tc were comparable. High-power electron accelerators are an attractive option for producing (99)Mo on a national scale. PMID:23552053

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

2013-04-03

409

Image, Image, Image  

ERIC Educational Resources Information Center

|With all the talk today about accountability, budget cuts, and the closing of programs in public education, teachers cannot overlook the importance of image in the field of industrial technology. It is very easy for administrators to cut ITE (industrial technology education) programs to save school money--money they might shift to teaching the…

Howell, Robert T.

2004-01-01

410

Synthesis of a potent and selective 18F-labeled ?-opioid receptor antagonist derived from the Dmt-Tic pharmacophore for PET imaging  

PubMed Central

H-Dmt-Tic-?-Lys(Z)-OH (1) was used in the synthesis of 18F-labeled opioids for positron emission tomography (PET) imaging by coupling N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB) with Boc-Dmt-Tic-?-Lys(Z)-OH under slightly basic conditions at 37 °C for 15 min, deprotected with TFA and HPLC purification in 120 min with a decay-corrected radiochemical 25–30% yield of [18F]-1 (n = 5) and specific activity ca. 46 GBq/µmol. Autoradiography uptake of [18F]-1 in striatum and cortex was blocked by 1 and UFP-501 demonstrating specific binding to ?-opioid receptors. MicroPET imaging revealed the absence of [18F]-1 in rat brain, suggesting its suitability for imaging peripheral ?-opioid receptors.

Ryu, Eun Kyoung; Wu, Zhanhong; Chen, Kai; Lazarus, Lawrence H.; Marczak, Ewa, D.; Sasaki, Yusuke; Ambo, Akihiro; Salvadori, Severo; Ren, Chuancheng; Zhao, Heng; Balboni, Gianfranco; Chen, Xiaoyuan

2009-01-01

411

System identification of lossless layered media from input-output data  

NASA Astrophysics Data System (ADS)

The interior of the Earth is modeled as a lossless layered medium, and the reconstruction of the parameters of such a medium from the input and the output (input-output data) are studied. The study assumes that the input-output data is noise free, and derives a so-called layer stripping algorithm for the reconstruction of the parameters of the medium. The algorithm is just one of the many versions of layer stripping algorithms that are available in the literature. The study then assumes that both the input and the output are corrupted by noise, and derives two new methods for the estimation of the parameters of the medium using the noisy input-output data. The methods are based on the estimation of the parameters of an ARX-representation of a lossless layered medium. The distinction between the two methods is that in one method the ARX parameters are free, while in the other method the ARX parameters have to correspond to parameters of a lossless layered medium that are physically realistic. The methods are illustrated by means of a numerical experiment.

Vanderwoude, J. W.

1989-11-01

412

Distal dendritic inputs control neuronal activity by heterosynaptic potentiation of proximal inputs  

PubMed Central

Synaptic inputs onto distal dendritic tufts are believed to function by modulating time-locked proximal inputs. However, little is known about the function of these inputs when proximal synapses are not coincident or silent. Surprisingly we found that activation of apical tuft synapses alone resulted in heterosynaptic potentiation of proximal synapses. In mouse adult hippocampal CA1 pyramidal neurons, we show that activation of distal inputs from the entorhinal cortex specifically strengthens proximal synapses projecting from CA3. This AMPA receptor-mediated potentiation is accompanied by increased synaptic GluN2B-containing NMDA receptors, which are normally restricted to juvenile animals. These two synaptic modifications interact to generate striking bi-directional metaplastic changes. Heterosynaptically potentiated synapses become resistant to subsequent long-term potentiation (LTP) as the two forms of AMPA receptor-mediated potentiation mutually occlude. However this is only true when the LTP induction protocol is relatively weak. When it is strong and repeated, the magnitude of LTP after heterosynaptic plasticity is greatly increased, specifically through the activation of GluN2B-containing NMDA receptors. Thus in addition to strengthening proximal apical synapses, heterosynaptic plasticity shifts the input-selectivity of CA1 neurons and expands the dynamic range of LTP, resulting in neurons that are tuned to greatly potentiate strong CA3 inputs. These results show that one set of inputs can exert long-lasting heterosynaptic control over another, allowing the interplay of two functionally and spatially distinct pathways, thereby greatly expanding the repertoire of cellular and network plasticity.

Han, Edward B.; Heinemann, Stephen F.

2013-01-01

413

Lattices of processes in graphs with inputs  

SciTech Connect

This article is a continuation of others work, presenting a detailed analysis of finite lattices of processes in graphs with input nodes. Lattices of processes in such graphs are studied by representing the lattices in the form of an algebra of pairs. We define the algebra of pairs somewhat generalizing the definition. Let K and D be bounded distributive lattices. A sublattice {delta} {contained_in} K x D is called an algebra of pairs if for all K {element_of} K we have (K, 1{sub D}) {element_of} {delta} and for all d {element_of} D we have (O{sub K}).

Shakhbazyan, K.V.

1995-09-01

414

Approximate input physics for stellar modelling  

NASA Astrophysics Data System (ADS)

We present a simple and efficient, yet reasonably accurate, equation of state, which at the moderately low temperatures and high densities found in the interiors of stars less massive than the Sun is substantially more accurate than its predecessor by Eggleton, Faulkner & Flannery. Along with the most recently available values in tabular form of opacities, neutrino loss rates, and nuclear reaction rates for a selection of the most important reactions, this provides a convenient package of input physics for stellar modelling. We briefly discuss a few results obtained with the updated stellar evolution code.

Pols, Omno R.; Tout, Christopher A.; Eggleton, Peter P.; Han, Zhanwen

1995-06-01

415

Image-based Participating Media  

Microsoft Academic Search

Light transport inside participating media, like fog or water, involves complex interaction phenomena, which make traditional 3D rendering approaches challenging and computationally expensive. To circumvent this, we propose an image-based method which adds perceptually plausible participating media effects to a single, clean high dy- namic range image. We impose no prior requirements on the input image, and show that the

Jorge Lopez-Moreno; Angel Cabanes; Diego Gutierrez

2008-01-01

416

Synthetic Fingerprint-Image Generation  

Microsoft Academic Search

Introduces a method for the generation of synthetic fingerprint images. Gabor-like space-variant filters are used for iteratively expanding an initially empty image containing just one or a few seeds. A directional image model, whose inputs are the number and location of the fingerprint cores and deltas, is used for tuning the filters according to the underlying ridge orientation. Very realistic

Raffaele Cappelli; Dario Maio; Davide Maltoni; Ali Erol

2000-01-01

417

Perception-based image editing  

Microsoft Academic Search

Image editing and post-processing techniques have matured over the years, making it difficult (verging on impossible) to assess whether an image has been digitally enhanced or doctored somehow. However, complex manipulations still rely on skilled user input, painstakingly painting over pixels. We present our recent and on-going work on advanced image editing techniques, extending current tools by leveraging the limitations

Diego Gutierrez

2009-01-01

418

Linear and quadratic models of point process systems: contributions of patterned input to output.  

PubMed

In the 1880's Volterra characterised a nonlinear system using a functional series connecting continuous input and continuous output. Norbert Wiener, in the 1940's, circumvented problems associated with the application of Volterra series to physical problems by deriving from it a new series of terms that are mutually uncorrelated with respect to Gaussian processes. Subsequently, Brillinger, in the 1970's, introduced a point-process analogue of Volterra's series connecting point-process inputs to the instantaneous rate of point-process output. We derive here a new series from this analogue in which its terms are mutually uncorrelated with respect to Poisson processes. This new series expresses how patterned input in a spike train, represented by third-order cross-cumulants, is converted into the instantaneous rate of an output point-process. Given experimental records of suitable duration, the contribution of arbitrary patterned input to an output process can, in principle, be determined. Solutions for linear and quadratic point-process models with one and two inputs and a single output are investigated. Our theoretical results are applied to isolated muscle spindle data in which the spike trains from the primary and secondary endings from the same muscle spindle are recorded in response to stimulation of one and then two static fusimotor axons in the absence and presence of a random length change imposed on the parent muscle. For a fixed mean rate of input spikes, the analysis of the experimental data makes explicit which patterns of two input spikes contribute to an output spike. PMID:22721703

Lindsay, K A; Rosenberg, J R

2012-06-18

419

Echo state property linked to an input: exploring a fundamental characteristic of recurrent neural networks.  

PubMed

The echo state property is a key for the design and training of recurrent neural networks within the paradigm of reservoir computing. In intuitive terms, this is a passivity condition: a network having this property, when driven by an input signal, will become entrained by the input and develop an internal response signal. This excited internal dynamics can be seen as a high-dimensional, nonlinear, unique transform of the input with a rich memory content. This view has implications for understanding neural dynamics beyond the field of reservoir computing. Available definitions and theorems concerning the echo state property, however, are of little practical use because they do not relate the network response to temporal or statistical properties of the driving input. Here we present a new definition of the echo state property that directly connects it to such properties. We derive a fundamental 0-1 law: if the input comes from an ergodic source, the network response has the echo state property with probability one or zero, independent of the given network. Furthermore, we give a sufficient condition for the echo state property that connects statistical characteristics of the input to algebraic properties of the network connection matrix. The mathematical methods that we employ are freshly imported from the young field of nonautonomous dynamical systems theory. Since these methods are not yet well known in neural computation research, we introduce them in some detail. As a side story, we hope to demonstrate the eminent usefulness of these methods. PMID:23272918

Manjunath, G; Jaeger, H

2012-12-28

420

T*1e and T*2e maps derived in vivo from the rat using longitudinally detected electron spin resonance phase imaging: application to abdominal oxygen mapping.  

PubMed

A novel imaging modality is introduced which uses radiofrequency longitudinally detected electron spin resonance (RF-LODESR). It is capable of providing qualitative and semiquantitative information on a variety of parameters reflecting physiological function, the most significant being tissue oxygenation. Effective spin-lattice (T*1e) and spin-spin (T*2e) electronic relaxation time maps of the abdomen of living 200-g rats were generated after intravenous administration of a triarylmethyl free radical (TAM). These maps were used to evaluate oxygen distribution. Differences between the liver, kidneys, and bladder were noted. Conclusions were made regarding the distribution, perfusion, and excretion rate of the contrast medium. Ligature-induced anoxia in the kidney was also visualized. LODESR involves transverse ESR irradiation with a modulated excitation, and observing oscillations in the spin magnetization parallel to the main magnetic field. The T*1e and T*2e maps were calculated from a set of LODESR signal phase images collected at different detection frequencies. Each phase image also provides qualitative information on tissue oxygen levels without any further processing. This method presents an alternative to the conventional transverse ESR linewidth-based oximetry methods, particularly for animal whole-body imaging applications. PMID:11746590

Panagiotelis, I; Nicholson, I; Foster, M A; Hutchison, J M

2001-12-01