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1

Image-Derived Input Function for Human Brain Using High Resolution PET Imaging with [11  

E-print Network

](R)-rolipram and [11 C]PBR28 Paolo Zanotti-Fregonara1 *, Jeih-San Liow1 , Masahiro Fujita1 , Elodie Dusch2 , Sami S of the methods required arterial blood samples to scale the image-input, and four were blood-free methods-S, Fujita M, Dusch E, Zoghbi SS, et al. (2011) Image-Derived Input Function for Human Brain Using High

Shen, Jun

2

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

3

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

PubMed

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

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

2012-12-01

4

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

NASA Astrophysics Data System (ADS)

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

Fung, Edward K.; Carson, Richard E.

2013-03-01

5

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

PubMed Central

Full quantitative analysis of brain PET data requires knowledge of the arterial input function into the brain. Such data are normally acquired by arterial sampling with corrections for delay and dispersion to account for the distant sampling site. Several attempts have been made to extract an image-derived input function (IDIF) directly from the internal carotid arteries that supply the brain and are often visible in brain PET images. We have devised a method of delineating the internal carotids in co-registered MR images using the level-set method and applying the segmentations to PET images using a novel centerline approach. Centerlines of the segmented carotids were modeled as cubic splines and re-registered in PET images summed over the early portion of the scan. Using information from the anatomical center of the vessel should minimize partial volume and spillover effects. Centerline time-activity curves were taken as the mean of the values for points along the centerline interpolated from neighboring voxels. A scale factor correction was derived from calculation of cerebral blood flow (CBF) using gold standard arterial blood measurements. We have applied the method to human subject data from multiple injections of [15O]water on the HRRT. The method was assessed by calculating the area under the curve (AUC) of the IDIF and the CBF, and comparing these to values computed using the gold standard arterial input curve. The average ratio of IDIF to arterial AUC (apparent recovery coefficient: aRC) across 9 subjects with multiple (n = 69) injections was 0.49 ± 0.09 at 0–30 s post tracer arrival, 0.45 ± 0.09 at 30–60 s, and 0.46 ± 0.09 at 60–90 s. Grey and white matter CBF values were 61.4 ± 11.0 and 15.6 ± 3.0 mL/min/100g tissue using sampled blood data. Using IDIF centerlines scaled by the average aRC over each subjects’ injections, gray and white matter CBF values were 61.3 ± 13.5 and 15.5 ± 3.4 mL/min/100g tissue. Using global average aRC values, the means were unchanged, and intersubject variability was noticeably reduced. This MR-based centerline method with local re-registration to [15O]water PET yields a consistent IDIF over multiple injections in the same subject, thus permitting the absolute quantification of CBF without arterial input function measurements. PMID:23442733

Fung, Edward K; Carson, Richard E

2013-01-01

6

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

PubMed Central

Purpose We investigated the use of a simple calibration method to remove bias in previously proposed approaches to image-derived input functions (IDIFs) when used to calculate the metabolic uptake rate of glucose (Km) from dynamic [18F]-FDG PET scans of the thigh. Our objective was to obtain nonbiased, low-variance Km values without blood sampling. Materials and methods We evaluated eight previously proposed IDIF methods. Km values derived from these IDIFs were compared with Km values calculated from the arterial blood samples (gold standard). We used linear regression to extract calibration parameters to remove bias. Following calibration, cross-validation and bootstrapping were used to estimate the mean square error and variance. Results Three of the previously proposed methods failed mainly because of zero-crossings of the IDIF. The remaining five methods were improved by calibration, yielding unbiased Km values. The method with the lowest SD yielded an SD of 0.0017/min – that is, below 10% of the muscle Km value in this study. Conclusion Previously proposed IDIF methods can be improved by using a simple calibration procedure. The calibration procedure may be used in other studies, thus obviating the need for arterial blood sampling, once the calibration parameters have been established in a subgroup of participants. The method has potential for use in other parts of the body as it is robust with regard to partial volume effects. PMID:24335879

Reichkendler, Michala H.; Larsen, Rasmus; Auerbach, Pernille; Højgaard, Liselotte; Nielsen, Henning B.; Ploug, Thorkil; Stallknecht, Bente; Holm, Søren

2014-01-01

7

Image Derived Input Function for [18F]-FEPPA: Application to Quantify Translocator Protein (18 kDa) in the Human Brain  

PubMed Central

In [18F]-FEPPA positron emission topography (PET) imaging, automatic blood sampling system (ABSS) is currently the gold standard to obtain the blood time activity curve (TAC) required to extract the input function (IF). Here, we compare the performance of two image-based methods of IF extraction to the ABSS gold standard method for the quantification of translocator protein (TSPO) in the human brain. The IFs were obtained from a direct delineation of the internal carotid signal (CS) and a new concept of independent component analysis (ICA). PET scans were obtained from 18 healthy volunteers. The estimated total distribution volume (VT) by CS-IF and ICA-IF were compared to the reference VT obtained by ABSS-IF in the frontal and temporal cortex, cerebellum, striatum and thalamus regions. The VT values estimated using ICA-IF were more reliable than CS-IF for all brain regions. Specifically, the slope regression in the frontal cortex with ICA-IF was r2?=?0.91 (p<0.05), and r2?=?0.71 (p<0.05) using CS-IF. PMID:25549260

Mabrouk, Rostom; Rusjan, Pablo M.; Mizrahi, Romina; Jacobs, Mark F.; Koshimori, Yuko; Houle, Sylvain; Ko, Ji Hyun; Strafella, Antonio P.

2014-01-01

8

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

PubMed Central

Purpose Quantification of small animal PET images necessitates knowledge of the plasma input function (PIF). We propose and validate a simplified hybrid single-input-dual-output (HSIDO) algorithm to estimate the PIF. Procedures The HSIDO algorithm integrates the peak of the input function from two ROI TACs with a tail segment expressed by a sum of two exponentials. Partial volume parameters are optimized simultaneously. The algorithm is validated using both simulated and real small animal PET images. In addition, the algorithm is compared to existing techniques in terms of area under curve (AUC) error, bias and precision of compartmental model micro-parameters. Results In general, the HSIDO method generated PIF with significantly (P<0.05) less AUC error, lower bias, and improved precision of kinetic estimates in comparison to the reference method. Conclusions HISDO is an improved modeling based PIF estimation method. This method can be applied for quantitative analysis of small animal dynamic PET studies. PMID:19949986

Su, Yi; Shoghi, Kooresh I.

2014-01-01

9

Image annotation by input-output structural grouping sparsity.  

PubMed

Automatic image annotation (AIA) is very important to image retrieval and image understanding. Two key issues in AIA are explored in detail in this paper, i.e., structured visual feature selection and the implementation of hierarchical correlated structures among multiple tags to boost the performance of image annotation. This paper simultaneously introduces an input and output structural grouping sparsity into a regularized regression model for image annotation. For input high-dimensional heterogeneous features such as color, texture, and shape, different kinds (groups) of features have different intrinsic discriminative power for the recognition of certain concepts. The proposed structured feature selection by structural grouping sparsity can be used not only to select group-of-features but also to conduct within-group selection. Hierarchical correlations among output labels are well represented by a tree structure, and therefore, the proposed tree-structured grouping sparsity can be used to boost the performance of multitag image annotation. In order to efficiently solve the proposed regression model, we relax the solving process as a framework of the bilayer regression model for multilabel boosting by the selection of heterogeneous features with structural grouping sparsity (Bi-MtBGS). The first-layer regression is to select the discriminative features for each label. The aim of the second-layer regression is to refine the feature selection model learned from the first layer, which can be taken as a multilabel boosting process. Extensive experiments on public benchmark image data sets and real-world image data sets demonstrate that the proposed approach has better performance of multitag image annotation and leads to a quite interpretable model for image understanding. PMID:22262682

Han, Yahong; Wu, Fei; Tian, Qi; Zhuang, Yueting

2012-06-01

10

Limits to image reconstruction from restricted angular input  

SciTech Connect

Distortion in an object due to the unavailability of some Fourier components in a cone-shaped region is analyzed. The results throw light on the factors that limit the accuracy in reconstructing objects from limited-angle input in practice. It is also shown that norm- or entropy-related reconstruction methods are not expected to improve the fidelity of the reconstructed images; only more a priori knowledge of exact nature on the object can serve this purpose. 8 figures.

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

1980-11-01

11

Deriving Intrinsic Images from Image Sequences  

Microsoft Academic Search

Intrinsic images are a useful midlevel description of scenes proposed by Barrow and Tenenbaum (1). An image is de- composed into two images: a reflectance image and an il- lumination image. Finding such a decomposition remains a difficult problem in computer vision. Here we focus on a slightly easier problem: given a sequence of im- ages where the reflectance is

Yair Weiss

2001-01-01

12

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

13

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

14

Visual Image Filtering at the Level of Cortical Input  

Microsoft Academic Search

A computational model of the spatial-frequency filtering processes at the level of 4C ? layer of the visual striate cortex is being proposed. The model does not interfere with the filter- ing performed by the cortical receptive fields itself, and the focus of attention is restricted to the cortical input. The model is based on the literature data concerning the

Aleksandr Bulatov; Algis Bertulis

2004-01-01

15

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

NASA Astrophysics Data System (ADS)

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

Hancilar, Ufuk; Harmandar, Ebru; Çakti, Eser

2014-05-01

16

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

PubMed Central

The effect of using spectral transform images as input data on segmentation quality and its potential effect on products generated by object-based image analysis are explored in the context of land cover classification in Accra, Ghana. Five image data transformations are compared to untransformed spectral bands in terms of their effect on segmentation quality and final product accuracy. The relationship between segmentation quality and product accuracy is also briefly explored. Results suggest that input data transformations can aid in the delineation of landscape objects by image segmentation, but the effect is idiosyncratic to the transformation and object of interest. PMID:21673829

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

2011-01-01

17

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

18

Using Whole-House Field Tests to Empirically Derive Moisture Buffering Model Inputs  

SciTech Connect

Building energy simulations can be used to predict a building's interior conditions, along with the energy use associated with keeping these conditions comfortable. These models simulate the loads on the building (e.g., internal gains, envelope heat transfer), determine the operation of the space conditioning equipment, and then calculate the building's temperature and humidity throughout the year. The indoor temperature and humidity are affected not only by the loads and the space conditioning equipment, but also by the capacitance of the building materials, which buffer changes in temperature and humidity. This research developed an empirical method to extract whole-house model inputs for use with a more accurate moisture capacitance model (the effective moisture penetration depth model). The experimental approach was to subject the materials in the house to a square-wave relative humidity profile, measure all of the moisture transfer terms (e.g., infiltration, air conditioner condensate) and calculate the only unmeasured term: the moisture absorption into the materials. After validating the method with laboratory measurements, we performed the tests in a field house. A least-squares fit of an analytical solution to the measured moisture absorption curves was used to determine the three independent model parameters representing the moisture buffering potential of this house and its furnishings. Follow on tests with realistic latent and sensible loads showed good agreement with the derived parameters, especially compared to the commonly-used effective capacitance approach. These results show that the EMPD model, once the inputs are known, is an accurate moisture buffering model.

Woods, J.; Winkler, J.; Christensen, D.; Hancock, E.

2014-08-01

19

Fluorescein Derivatives in Intravital Fluorescence Imaging  

PubMed Central

Intravital fluorescence microscopy enables the direct imaging of fluorophores in vivo and advanced techniques such as fluorescence lifetime imaging (FLIM) enable the simultaneous detection of multiple fluorophores. Consequently, it is now possible to record distribution and metabolism of a chemical in vivo and to optimise the delivery of fluorophores in vivo. Recent clinical applications with fluorescein and other intravital fluorescent stains have occurred in neurosurgery, dermatology [including photodynamic therapy (PDT)] and endomicroscopy. Potential uses have been identified in periodontal disease, skin graft and cancer surgery. Animal studies have demonstrated that diseased tissue can be specifically stained with fluorophore conjugates. This review focuses on the fluorescein derived fluorophores in common clinical use and provides examples of novel applications from studies in tissue samples. PMID:24709799

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

2013-01-01

20

Multiple-input ghost imaging via sparsity constraints with thermal light  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

21

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

22

Java Library for Input and Output of Image Data and Metadata  

NASA Technical Reports Server (NTRS)

A Java-language library supports input and output (I/O) of image data and metadata (label data) in the format of the Video Image Communication and Retrieval (VICAR) image-processing software and in several similar formats, including a subset of the Planetary Data System (PDS) image file format. The library does the following: It provides low-level, direct access layer, enabling an application subprogram to read and write specific image files, lines, or pixels, and manipulate metadata directly. Two coding/decoding subprograms ("codecs" for short) based on the Java Advanced Imaging (JAI) software provide access to VICAR and PDS images in a file-format-independent manner. The VICAR and PDS codecs enable any program that conforms to the specification of the JAI codec to use VICAR or PDS images automatically, without specific knowledge of the VICAR or PDS format. The library also includes Image I/O plugin subprograms for VICAR and PDS formats. Application programs that conform to the Image I/O specification of Java version 1.4 can utilize any image format for which such a plug-in subprogram exists, without specific knowledge of the format itself. Like the aforementioned codecs, the VICAR and PDS Image I/O plug-in subprograms support reading and writing of metadata.

Deen, Robert; Levoe, Steven

2003-01-01

23

Image deblurring using derivative compressed sensing for optical imaging application.  

PubMed

The problem of reconstruction of digital images from their blurred and noisy measurements is unarguably one of the central problems in imaging sciences. Despite its ill-posed nature, this problem can often be solved in a unique and stable manner, provided appropriate assumptions on the nature of the images to be recovered. In this paper, however, a more challenging setting is considered, in which accurate knowledge of the blurring operator is lacking, thereby transforming the reconstruction problem at hand into a problem of blind deconvolution. As a specific application, the current presentation focuses on reconstruction of short-exposure optical images measured through atmospheric turbulence. The latter is known to give rise to random aberrations in the optical wavefront, which are in turn translated into random variations of the point spread function of the optical system in use. A standard way to track such variations involves using adaptive optics. Thus, for example, the Shack-Hartmann interferometer provides measurements of the optical wavefront through sensing its partial derivatives. In such a case, the accuracy of wavefront reconstruction is proportional to the number of lenslets used by the interferometer and, hence, to its complexity. Accordingly, in this paper, we show how to minimize the above complexity through reducing the number of the lenslets while compensating for undersampling artifacts by means of derivative compressed sensing. Additionally, we provide empirical proof that the above simplification and its associated solution scheme result in image reconstructions, whose quality is comparable to the reconstructions obtained using conventional (dense) measurements of the optical wavefront. PMID:22434800

Rostami, Mohammad; Michailovich, Oleg; Wang, Zhou

2012-07-01

24

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

25

Global Auroral Energy Deposition Derived from Polar UVI Images  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

26

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. PMID:21992376

Shen, Jun

2011-01-01

27

Synthesis and characterization of styrylchromone derivatives as ?-amyloid imaging agents  

Microsoft Academic Search

Several promising agents have been synthesized and evaluated for in vivo imaging probes of ?-amyloid plaques in Alzheimer’s disease (AD) brain. Recently, we have developed flavone derivatives, which possess the basic structure of the 2-phenylchromone, as useful candidates for amyloid imaging agents. In an attempt to further develop novel tracers, we synthesized and evaluated a series of 2-styrylchromone derivatives, which

Masahiro Ono; Yoshifumi Maya; Mamoru Haratake; Morio Nakayama

2007-01-01

28

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

PubMed Central

Purpose Accurate determination of the plasma input function (IF) is essential for absolute quantification of physiological parameters in positron emission tomography (PET). However, it requires an invasive and tedious procedure of arterial blood sampling that is challenging in mice because of the limited blood volume. In this study, a hybrid modeling approach is proposed to estimate the plasma IF of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) in mice using accumulated radioactivity in urinary bladder together with a single late-time blood sample measurement. Methods Dynamic PET scans were performed on nine isoflurane-anesthetized male C57BL/6 mice after a bolus injection of [18F]FDG at the lateral caudal vein. During a 60- or 90-min scan, serial blood samples were taken from the femoral artery. Image data were reconstructed using filtered backprojection with CT-based attenuation correction. Total accumulated radioactivity in the urinary bladder was fitted to a renal compartmental model with the last blood sample and a 1-exponential function that described the [18F]FDG clearance in blood. Multiple late-time blood sample estimates were calculated by the blood [18F]FDG clearance equation. A sum of 4-exponentials was assumed for the plasma IF that served as a forcing function to all tissues. The estimated plasma IF was obtained by simultaneously fitting the [18F]FDG model to the time-activity curves (TACs) of liver and muscle and the forcing function to early (0–1 min) left-ventricle data (corrected for delay, dispersion, partial-volume effects and erythrocytes uptake) and the late-time blood estimates. Using only the blood sample acquired at the end of the study to estimate the IF and the use of liver TAC as an alternative IF were also investigated. Results The area under the plasma TACs calculated for all studies using the hybrid approach was not significantly different from that using all blood samples. [18F]FDG uptake constants in brain, myocardium, skeletal muscle and liver computed by the Patlak analysis using estimated and measured plasma TACs were in excellent agreement (slope ~ 1; R2 > 0.938). The IF estimated using only the last blood sample acquired at the end of the study and the use of liver TAC as plasma IF provided less reliable results. Conclusions The estimated plasma IFs obtained with the hybrid model agreed well with those derived from arterial blood sampling. Importantly, the proposed method obviates the need of arterial catheterization, making it possible to perform repeated dynamic [18F]FDG PET studies on the same animal. Liver TAC is unsuitable as an input function for absolute quantification of [18F]FDG PET data. PMID:23322346

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

2013-01-01

29

Fig. 2. Results of the color segmentation. Evaluation of the initialization procedure. (a) Input image. (b) Color segmentation result Random initialization. (c) Color  

E-print Network

procedure. (a) Input image. (b) Color segmentation result ­ Random initialization. (c) Color segmentation segmentation. Evaluation of the initialization procedure. (a) Input image. (b) Color segmentation result parameter. (a) Input noiseless image. (b) Color segmentation result ­ no diffusion. (c) Color segmentation

Whelan, Paul F.

30

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

31

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

PubMed

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

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

2011-04-01

32

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

33

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

SciTech Connect

The extraction of pure arterial time-activity curves (TACs) from dynamic PET images of a small animal heart using factor analysis of dynamic structures (FADS) was found to be unsuccessful due to the small size of the cardiac chamber that causes extensive mixture of TACs of different structures. In this study, we used digital phantoms of the left ventricle (LV cavity size: 1-2 cm) and small monkey (LV cavity size: {approx} 2 cm) dynamic FDG PET studies to evaluate FADS for extracting the pure blood-pool TACs by adding a single blood sample (taken at a late scan time) constraint. In the digital phantom studies, spillover fractions in the extracted blood-pool TACs using FADS without a blood sample constraint (FADS(-)) and with a blood sample constraint (FADS(+)) were 3%-91% and < 3%, respectively. In the monkey studies (n = 4), FADS(+) extracted blood-pool TACs matched well with the arterialized well counter measurements (% differences of curve integration: FADS(-) < 82%; FADS(+) < 9%). The microparameters (K*{sub 1}, k*{sub 2}, k*{sub 3}, k*{sub 4}) and macroparameters (K{sub nlr}), obtained from the FADS(+) blood-pool TACs, were similar to those obtained from plasma samples in a three-compartment model fitting (% differences of K{sub nlr}: phantom studies < 5%; monkey studies < 9%). The FADS technique with a single-blood sample has the potential to extract the pure blood-pool TACs directly from dynamic PET images of a small animal without multiple blood sampling, region of interest definition or spillover correction. 14 refs., 5 figs., 3 tabs.

Wu, Hsiao-Ming; Huang, Sung-Cheng; Allada, V. [Univ. of California, Los Angeles, CA (United States)] [and others

1996-10-01

34

Light field creating and imaging with different order intensity derivatives  

NASA Astrophysics Data System (ADS)

Microscopic image restoration and reconstruction is a challenging topic in the image processing and computer vision, which can be widely applied to life science, biology and medicine etc. A microscopic light field creating and three dimensional (3D) reconstruction method is proposed for transparent or partially transparent microscopic samples, which is based on the Taylor expansion theorem and polynomial fitting. Firstly the image stack of the specimen is divided into several groups in an overlapping or non-overlapping way along the optical axis, and the first image of every group is regarded as reference image. Then different order intensity derivatives are calculated using all the images of every group and polynomial fitting method based on the assumption that the structure of the specimen contained by the image stack in a small range along the optical axis are possessed of smooth and linear property. Subsequently, new images located any position from which to reference image the distance is ?z along the optical axis can be generated by means of Taylor expansion theorem and the calculated different order intensity derivatives. Finally, the microscopic specimen can be reconstructed in 3D form using deconvolution technology and all the images including both the observed images and the generated images. The experimental results show the effectiveness and feasibility of our method.

Wang, Yu; Jiang, Huan

2014-10-01

35

Landsat Thematic Mapper image-derived MTF  

NASA Technical Reports Server (NTRS)

The Landsat Image Data Quality Analysis (LIDQA) Program conducted by NASA has the objective to quantify the performance of the Thematic Mapper (TM) on the Landsat-4 and Landsat-5 spacecraft. The interest in the spatial resolution performance of the TM is partly related to the decrease of the instantaneous field of view (IFOV) from 80 m for the MSS to 30 m for the TM. Studies related to the preflight line spread function (LSF), square wave response (SWR), and theoretical component modeling of the TM system modulation transfer function (MTF) have been conducted. However, the need remains to estimate the MTF of the complete system. The present paper is concerned with investigations related to this task. Attention is given to three approaches for measuring the MTF of the TM system from imagery.

Schowengerdt, R. A.; Archwamety, C.; Wrigley, R. C.

1985-01-01

36

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

37

A comparison of individual and population-derived vascular input functions for quantitative DCE-MRI in rats.  

PubMed

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) can quantitatively and qualitatively assess physiological characteristics of tissue. Quantitative DCE-MRI requires an estimate of the time rate of change of the concentration of the contrast agent in the blood plasma, the vascular input function (VIF). Measuring the VIF in small animals is notoriously difficult as it requires high temporal resolution images limiting the achievable number of slices, field-of-view, spatial resolution, and signal-to-noise. Alternatively, a population-averaged VIF could be used to mitigate the acquisition demands in studies aimed to investigate, for example, tumor vascular characteristics. Thus, the overall goal of this manuscript is to determine how the kinetic parameters estimated by a population based VIF differ from those estimated by an individual VIF. Eight rats bearing gliomas were imaged before, during, and after an injection of Gd-DTPA. K(trans), ve, and vp were extracted from signal-time curves of tumor tissue using both individual and population-averaged VIFs. Extended model voxel estimates of K(trans) and ve in all animals had concordance correlation coefficients (CCC) ranging from 0.69 to 0.98 and Pearson correlation coefficients (PCC) ranging from 0.70 to 0.99. Additionally, standard model estimates resulted in CCCs ranging from 0.81 to 0.99 and PCCs ranging from 0.98 to 1.00, supporting the use of a population based VIF if an individual VIF is not available. PMID:24556502

Hormuth, David A; Skinner, Jack T; Does, Mark D; Yankeelov, Thomas E

2014-05-01

38

Derivate  

NSDL National Science Digital Library

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

2010-01-01

39

Antibody-derived in vivo imaging of tau pathology.  

PubMed

Antibodies or their derivatives as imaging probes for pathological tau protein have great potential, but have not been well studied. In particular, smaller, single-chain-variable antibody fragments (scFv's) are attractive for detecting tau lesions in live subjects. Here, we generated libraries of scFv's and identified numerous phospho-tau-selective scFv's. Peripheral injection of one of these scFv's consistently resulted in a strong in vivo brain signal in transgenic tauopathy mice, but not in wild-type or amyloid-? plaque mice. The parent tau antibody provided similar results, albeit with a weaker signal intensity. The imaging signal correlated very well with colocalization of the probe with intraneuronal tau aggregates. Both were associated with markers of endosomes, autophagosomes, and lysosomes, suggesting their interaction in these degradation pathways. Such specific antibody-derived imaging probes have great potential as diagnostic markers for Alzheimer's disease and related tauopathies. PMID:25505335

Krishnaswamy, Senthilkumar; Lin, Yan; Rajamohamedsait, Wajitha J; Rajamohamedsait, Hameetha B; Krishnamurthy, Pavan; Sigurdsson, Einar M

2014-12-10

40

Subthreshold membrane currents confer distinct tuning properties that enable neurons to encode the integral or derivative of their input  

PubMed Central

Neurons rely on action potentials, or spikes, to encode information. But spikes can encode different stimulus features in different neurons. We show here through simulations and experiments how neurons encode the integral or derivative of their input based on the distinct tuning properties conferred upon them by subthreshold currents. Slow-activating subthreshold inward (depolarizing) current mediates positive feedback control of subthreshold voltage, sustaining depolarization and allowing the neuron to spike on the basis of its integrated stimulus waveform. Slow-activating subthreshold outward (hyperpolarizing) current mediates negative feedback control of subthreshold voltage, truncating depolarization and forcing the neuron to spike on the basis of its differentiated stimulus waveform. Depending on its direction, slow-activating subthreshold current cooperates or competes with fast-activating inward current during spike initiation. This explanation predicts that sensitivity to the rate of change of stimulus intensity differs qualitatively between integrators and differentiators. This was confirmed experimentally in spinal sensory neurons that naturally behave as specialized integrators or differentiators. Predicted sensitivity to different stimulus features was confirmed by covariance analysis. Integration and differentiation, which are themselves inverse operations, are thus shown to be implemented by the slow feedback mediated by oppositely directed subthreshold currents expressed in different neurons. PMID:25620913

Ratté, Stéphanie; Lankarany, Milad; Rho, Young-Ah; Patterson, Adam; Prescott, Steven A.

2015-01-01

41

Subthreshold membrane currents confer distinct tuning properties that enable neurons to encode the integral or derivative of their input.  

PubMed

Neurons rely on action potentials, or spikes, to encode information. But spikes can encode different stimulus features in different neurons. We show here through simulations and experiments how neurons encode the integral or derivative of their input based on the distinct tuning properties conferred upon them by subthreshold currents. Slow-activating subthreshold inward (depolarizing) current mediates positive feedback control of subthreshold voltage, sustaining depolarization and allowing the neuron to spike on the basis of its integrated stimulus waveform. Slow-activating subthreshold outward (hyperpolarizing) current mediates negative feedback control of subthreshold voltage, truncating depolarization and forcing the neuron to spike on the basis of its differentiated stimulus waveform. Depending on its direction, slow-activating subthreshold current cooperates or competes with fast-activating inward current during spike initiation. This explanation predicts that sensitivity to the rate of change of stimulus intensity differs qualitatively between integrators and differentiators. This was confirmed experimentally in spinal sensory neurons that naturally behave as specialized integrators or differentiators. Predicted sensitivity to different stimulus features was confirmed by covariance analysis. Integration and differentiation, which are themselves inverse operations, are thus shown to be implemented by the slow feedback mediated by oppositely directed subthreshold currents expressed in different neurons. PMID:25620913

Ratté, Stéphanie; Lankarany, Milad; Rho, Young-Ah; Patterson, Adam; Prescott, Steven A

2014-01-01

42

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

NASA Astrophysics Data System (ADS)

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

Gillespie, A. R.

2013-12-01

43

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

PubMed Central

Purpose With the goal of facilitating tracer kinetic analysis in small-animal planar fluorescence imaging, an experimental method for characterizing tracer arterial input functions is presented. The proposed method involves exposing the common carotid arteries by surgical dissection, which can then be imaged directly during tracer injection and clearance. Procedures Arterial concentration curves of IRDye-700DX-carboxylate, IRDye-800CW-EGF, and IRDye-800CW conjugated to anti-EGFR Affibody are recovered from athymic female mice (n=12) by directly imaging exposed vessels. Images were acquired with two imaging protocols: a slow-kinetics approach (temporal resolution=45 s) to recover the arterial curves from two tracers simultaneously, and a fast-kinetics approach (temporal resolution=500 ms) to characterize the first-pass peak of a single tracer. Arterial input functions obtained by the carotid imaging technique, as well as plasma curves measured by blood sampling were fit with a biexponential pharmacokinetic model. Results Pharmacological fast- and slow-phase rate constants recovered with the proposed method were 0.37±0.26 and 0.007±0.001 min?1, respectively, for the IRDye700DX-C. For the IRDye800CW-EGF, the rate constants were 0.11±0.13 and 0.003±0.002 min?1. These rate constants did not differ significantly from those calculated previously by blood sampling, as determined by an F test; however, the between-subject variability was four times lower for arterial curves recovered using the proposed technique, compared with blood sampling. Conclusions The proposed technique enables the direct characterization of arterial input functions for kinetic analysis. As this method requires no additional instrumentation, it is immediately deployable in commercially available planar fluorescence imaging systems. PMID:24420443

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

2014-01-01

44

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

NASA Astrophysics Data System (ADS)

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 2003 along two major sediment transport pathways south and west of the Mississippi River mouth. Lignin profiles in these age-dated cores (210Pb geochronology) indicate artificial reservoir retention as a primary control on organic carbon quantity and quality reaching the margin post-1950, whereas pre-1950 sediments may reflect soil erosion due to land clearing and farming practices. Lignin (?8) concentrations (range 0.2 to 1.7) also indicate that TOCT delivery rates/decay processes have probably remained relatively consistent from proximal to distal stations along transects. The down-core profile at the Canyon station seems to be temporally linked and connected to inner shelf deposition, suggestive of rapid cross-shelf transport. Sources of terrestrially derived organic carbon were reflective of mixed angiosperms over the last 150 years in cores west and south of the Mississippi River delta. The lignin-phenol vegetation index (LPVI) (range 130.0 to 510) proved to be a sensitive indicator of source changes in these sediments and eliminated some of the variability compared to C/V (range 0.01 to 0.4) and S/V (range 0.9 to 2.1) ratios. Stochastic events such as hurricanes and large river floods have a measurable, albeit ephemeral, effect on the shelf TOCT record. Burial of TOCT on the river-dominated Louisiana continental margin is largely driven by anthropogenic land-use alterations in the last 150 years. Land-use changes in the Mississippi River basin and river damming have likely affected carbon cycling and TOCT burial on the Louisiana continental margin over a large spatial extent as observed by similar trends in cores from across and along the margin.

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

2011-03-01

45

Total electron and proton energy input during auroral substorms: Remote sensing with IMAGE-FUV  

E-print Network

] The IMAGE satellite carries three FUV imagers observing N2 LBH, O I 1356 A° , and HI Lyman a emissions contribution to the N2 LBH and O I 1356 A° emissions is calculated and subtracted to obtain the electron

California at Berkeley, University of

46

Biologically derived companding algorithm for high dynamic range mammography images.  

PubMed

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

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

2013-08-01

47

Peepholes with no strings attached: using image processing as input in camera-phones  

Microsoft Academic Search

Peepholes are virtual windows to large workspaces. Using a peephole provides an intuitive interface onto information spaces too large to be viewed on the screen of a mobile device. To date, these peephole systems have relied on tethered tracking devices or string connected to a desktop mouse to provide input to the system. In this paper, we investigate the use

Leonard Martin Ah Kun; Kuo-hung Lee; Gary Marsden

2007-01-01

48

The Atlases of Vesta derived from Dawn Framing Camera images  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

49

Time-delayed fluorescence imaging of a porphycene derivative  

NASA Astrophysics Data System (ADS)

Porphycenes are currently under investigation for use in Photodynamic therapy, which is a promising treatment for cancer. These materials, which display preferential uptake in cancerous cells, also exhibit high fluorescence yields, and can be used for tumour detection. Problems with steady-state fluorescence techniques such as background autofluorescence can be eliminated by the use of time-resolved techniques. Improved contrast can be obtained with time-resolved techniques because of the differing fluorescence lifetimes between autofluorescence and longer-living exogenous photosensitisers. An imaging system was constructed using a fast (200 ps) gated CCD camera and a pulsed 635 nm laser diode. A tissue phantom composed of polymethyl methacrylate (PMMA) with thirty-six wells of varying diameter and depth (10 mm to 1 mm) was assembled to test the system. The system was used to record images of a porphycene derivative within the wells at differing concentrations in an organic solvent. A tissue imitator was placed on top of the PMMA block at varying thickness. 10-4 M zinc phthalocyanine tetrasulfonate was also placed on top of the block to mimic autofluorescence. The results indicate that the time-gated imaging system can prevent background excitation scatter and fluorescence from a shorter-lived fluorophore from distorting the fluorescence signal from a longer-lived photosensitiser.

Gundy, Sarah L.; van der Putten, Wilhelm J.; Shearer, Andrew; Buckton, Daniel J.; Ryder, Alan G.; Ball, Michael

2003-06-01

50

Aerial infrared imaging reveals large nutrient-rich groundwater inputs to the ocean  

NASA Astrophysics Data System (ADS)

Regional high-resolution (0.1°C, 0.5 m) low-altitude thermal infrared imagery (TIR) reveals the exact input locations and fine-scale mixing structure of massive, cool groundwaters that discharge into the coastal zone as both diffuse flows and as >30 large point-sourced nutrient-rich plumes along the dry western half of the large volcanic island of Hawaii. These inputs are the sole source of new nutrient delivery to coastal waters in this oligotrophic setting. Water column profiling and nutrient sampling show that the plumes are cold, buoyant, nutrient-rich brackish mixtures of groundwater and seawater. By way of example, we illustrate in detail one of the larger plumes, which discharges ca. 12,000 m3 d-1 (ca. 8,600 m3 d-1 freshwater), rates comparable in volume to high-flux groundwater outputs in better-known tropical karst terrains. We further show how nutrient mixing trends may be integrated into TIR sea surface temperatures to produce surface water nutrient maps of regional extent.

Johnson, Adam G.; Glenn, Craig R.; Burnett, William C.; Peterson, Richard N.; Lucey, Paul G.

2008-08-01

51

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

Microsoft Academic Search

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

Yosio Edemir Shimabukuro; James A. Smith

1991-01-01

52

Fluctuations and movements of the Kuksai Glacier, western China, derived from Landsat image sequences  

NASA Astrophysics Data System (ADS)

Nine Landsat thematic mapper/enhanced thematic mapper (TM/ETM)+ images from 1998 to 2010 were analyzed to detect variations in the Kuksai Glacier of Mt. Muztagh Ata, western China. The velocities of glacial movement were quantified using the normalized cross-correlation (NCC) method. The surface debris cover of the glacier makes automated glacier outline mapping difficult, but provides useful features for monitoring glacier movement with the NCC method. Six displacement maps of the Kuksai Glacier, with an accuracy of 7 m, were derived from the band 3 of Landsat images. The NCC method is proven to be very effective in monitoring the activity of debris-covered glaciers. The results indicate that the velocity of the Kuksai Glacier is high in the upper portion and decreases downstream. For most of the years studied, the variability in the glacier movements in the middle and upper parts of the glacier, especially at 9 to 16 km upstream from the glacier terminal, is much larger than that in the downstream part. This study demonstrates that glacial movements can be routinely monitored using Landsat images, providing an input to and an opportunity for the detailed study of glacier dynamics.

Yang, Huaining; Yan, Shiyong; Liu, Guang; Ruan, Zhixing

2014-01-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

54

Design of an Intelligent Global Terminal Backstepping Controller without Derivative for a Class of Input Constrained High-Supersonic Missiles  

Microsoft Academic Search

A new intelligent global terminal backstepping design method is proposed for a class of high-supersonic missiles. It has several advantages as follows. Firstly, the differential bomb problem is avoided because of the no time derivative design concept. So the control law is simplified and the system becomes more stable and robust. Secondly, by adopting the global terminal control rule, a

Lei Junwei; Yu Hongyun; Huichao Zou

2008-01-01

55

Derivation of an indoor air averaging time model from the mass balance equation for the case of independent source inputs and fixed air exchange rates  

SciTech Connect

Previous human activity pattern-exposure models have required improved ways for handling the serial autocorrelation of pollutant concentrations in indoor and in-transit microenvironments. Because existing models often sample concentrations from microenvironmental distributions for different averaging times, one approach for handling this autocorrelation is to develop an averaging time model for each microenvironment of importance. The paper explores a new approach for developing averaging time models: deriving the model theoretically from the mass balance equation, which describes the relationship between the time series of the input and output concentrations of any pollutant introduced into a well-mixed chamber. Beginning with the mass balance equation, the paper derives an averaging time model that predicts the mean, variance, and autocorrelation of the time series of pollutant concentrations in a well-mixed chamber for any averaging time. The paper considers the case of a discrete model in which the input source concentration is a time series of independent, piecewise-constant concentrations of equal duration while the air exchange rate remains fixed. Because the model is derived theoretically, the model is exact for the conditions specified. The goal of the research is to provide human exposure researchers with basic concepts for designing and developing useful, practical algorithms for future exposure and indoor air quality models.

Switzer, P.; Ott, W.

1993-01-01

56

Cortical long-range interactions embed statistical knowledge of natural sensory input: a voltage-sensitive dye imaging study.  

PubMed

How is contextual processing as demonstrated with simplified stimuli, cortically enacted in response to ecologically relevant complex and dynamic stimuli? Using voltage-sensitive dye imaging, we captured mesoscopic population dynamics across several square millimeters of cat primary visual cortex. By presenting natural movies locally through either one or two adjacent apertures, we show that simultaneous presentation leads to mutual facilitation of activity. These synergistic effects were most effective when both movie patches originated from the same natural movie, thus forming a coherent stimulus in which the inherent spatio-temporal structure of natural movies were preserved in accord with Gestalt principles of perceptual organization. These results suggest that natural sensory input triggers cooperative mechanisms that are imprinted into the cortical functional architecture as early as in primary visual cortex. PMID:24358899

Onat, Selim; Jancke, Dirk; König, Peter

2013-01-01

57

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

PubMed Central

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

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

2014-01-01

58

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

USGS Publications Warehouse

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

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

1996-01-01

59

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

NASA Technical Reports Server (NTRS)

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

Shimabukuro, Yosio Edemir; Smith, James A.

1991-01-01

60

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

61

Derivation of quantitative information in NMR imaging: a phantom study.  

PubMed

The use of NMR imaging as a quantitative research tool requires insight into the relationship between various imaging techniques and their resultant images. Work was undertaken to elucidate this relationship by using the following procedure. First, a theoretical model of NMR imaging under various pulse sequences was elaborated. Subsequently, a series of inversion recovery and saturation recovery images of a particular object slice was generated by varying the sequence parameters. Finally, pure rho, T1 and T2 images of that slice were obtained by solving the corresponding model equations. This procedure was applied to a test phantom containing tubes with suitable reference substances, including aqueous solutions of agar, manganese chloride and deuterium, and water-fat mixtures. The concentration of various samples was chosen such as to yield rho, T1 and T2 values usually encountered in clinical NMR imaging. Experiments were carried out with a prototype resistive NMR imager with a static magnetic field of 0.14 T, corresponding to a hydrogen proton resonance frequency of 5.9 MHz. For most samples a weighted non-linear regression analysis showed the theoretical model to produce an adequate parametrisation of the data at the 5% significance level, given the number of data points and the experimental accuracy. The quantitative information extracted from the NMR imaging experiments, i.e. rho, T1 and T2, appeared to be in good agreement with the results of conventional methods, including NMR spectroscopy. The clinical efficacy of the proposed methods is currently being investigated. PMID:6514785

Bakker, C J; de Graaf, C N; van Dijk, P

1984-12-01

62

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

63

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

64

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. PMID:17383576

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

2007-01-01

65

Simplified molecular input-line entry system and International Chemical Identifier in the QSAR analysis of styrylquinoline derivatives as HIV-1 integrase inhibitors.  

PubMed

The simplified molecular input-line entry system (SMILES) and IUPAC International Chemical Identifier (InChI) were examined as representations of the molecular structure for quantitative structure-activity relationships (QSAR), which can be used to predict the inhibitory activity of styrylquinoline derivatives against the human immunodeficiency virus type 1 (HIV-1). Optimal SMILES-based descriptors give a best model with n = 26, r(2) = 0.6330, q(2) = 0.5812, s = 0.502, F = 41 for the training set and n = 10, r(2) = 0.7493, r(pred)(2) = 0.6235, R(m)(2) = 0.537, s = 0.541, F = 24 for the validation set. Optimal InChI-based descriptors give a best model with n = 26, r(2) = 0.8673, q(2) = 0.8456, s = 0.302, F = 157 for the training set and n = 10, r(2) = 0.8562, r(pred)(2) = 0.7715, R(m)(2) = 0.819, s = 0.329, F = 48 for the validation set. Thus, the InChI-based model is preferable. The described SMILES-based and InChI-based approaches have been checked with five random splits into the training and test sets. PMID:21352501

Toropova, Alla P; Toropov, Andrey A; Benfenati, Emilio; Gini, Giuseppina

2011-05-01

66

Geometric algebra colour image representations and derived total orderings for morphological operators Part I: Colour quaternions  

E-print Network

Geometric algebra colour image representations and derived total orderings for morphological is the first part of a series of studies which focus on defining colour total orderings based on geometric algebra represen- tations of colour images. In particular, in this article we focus on real quaternions

Angulo,Jesús

67

Imaging of transient electromagnetic soundings using a scaling approximate fréchet derivative  

NASA Astrophysics Data System (ADS)

The imaging algorithm is fast, robust, fully automated, and requires no initial model. The computation time, including the transformation from dH/dt to H-field, is approximately 0.5 sec/sounding/Mflop, which is 2-3 orders of magnitude faster than conventional least squares iterative inversion. The imaging produces models which fit the original data typically within 5-15%. The imaged models may be used as very good input models to an iterative least squares inversion program, can be implemented as an online interpretation in TEM instruments, and the imaging procedure lends itself readily to AIM strategies (Oldenburg 1991). Contoured model sections based on imaged models from soundings along profile lines give a very fast insight in the subsurface conductivity distribution.

Christensen, Niels B.

68

A technique for extracting physiological parameters and the required input function simultaneously from PET image measurements: theory and simulation study  

Microsoft Academic Search

Positron emission tomography (PET) is an important tool for enabling quantification of human brain function. However, quantitative studies using tracer kinetic modeling require the measurement of the tracer time-activity curve in plasma (PTAC) as the model input function. It is widely believed that the insertion of arterial lines and the subsequent collection and processing of the biomedical signal sampled from

David Dagan Feng; Koon-pong Wong; Chi-ming Wu; Wan-chi Siu

1997-01-01

69

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

PubMed Central

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

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

2014-01-01

70

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

71

MR image super-resolution reconstruction using sparse representation, nonlocal similarity and sparse derivative prior.  

PubMed

In magnetic resonance (MR) imaging, image spatial resolution is determined by various instrumental limitations and physical considerations. This paper presents a new algorithm for producing a high-resolution version of a low-resolution MR image. The proposed method consists of two consecutive steps: (1) reconstructs a high-resolution MR image from a given low-resolution observation via solving a joint sparse representation and nonlocal similarity L1-norm minimization problem; and (2) applies a sparse derivative prior based post-processing to suppress blurring effects. Extensive experiments on simulated brain MR images and two real clinical MR image datasets validate that the proposed method achieves much better results than many state-of-the-art algorithms in terms of both quantitative measures and visual perception. PMID:25638262

Zhang, Di; He, Jiazhong; Zhao, Yun; Du, Minghui

2015-03-01

72

Speckle noise reduction in ultrasound biomedical B-scan images using discrete topological derivative.  

PubMed

Over three decades, several despeckling techniques have been developed by researchers to reduce the speckle noise inherently present in ultrasound B-scan images without losing the diagnostic information. The topological derivative (TD) is the recently adopted technique in the area of biomedical image processing. In this work, we computed the topological derivative for an appropriate function associated to the ultrasound B-scan image gradient by assigning a diffusion factor k, which indicates the cost endowed to that particular image. In this article, a novel image denoising approach, called discrete topological derivative (DTD) has been implemented. The algorithm has been developed in MATLAB7.1 and tested over 200 ultrasound B-scan images of several organs such as the liver, kidney, gall bladder and pancreas. Further, the performance of the DTD algorithm has been estimated by calculating important performance metrics. A comparative study was carried out between the DTD and the traditional despeckling techniques. The calculated peak signal-to-noise ratio (PSNR) (the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation) value of the DTD despeckled liver image is found to be 28 which is comparable with the outperformed speckle reducing anisotropic diffusion (SRAD) filter. SRAD filter is an edge-sensitive diffusion method for speckled images of ultrasonic and radar imaging applications. Canny edge detection and visual inspection of DTD filtered images by the trained radiologist found that the DTD algorithm preserves the hypoechoic and hyperechoic regions resulting in improved diagnosis as well as tissue characterization. PMID:22230135

Damodaran, Nedumaran; Ramamurthy, Sivakumar; Velusamy, Sekar; Manickam, Gayathri Kanakaraj

2012-02-01

73

Synthesis and biological evaluation of ( E)-3-styrylpyridine derivatives as amyloid imaging agents for Alzheimer's disease  

Microsoft Academic Search

A new series of (E)-3-styrylpyridine derivatives as potential diagnostic imaging agents targeting amyloid plaques in Alzheimer's disease (AD) were synthesized and examined. When in vitro binding studies using AD brain homogenates were carried out with a series of styrylpyridine derivatives, (E)-2-Bromo-5-(4-dimethylaminostyryl)pyridine (7) with a dimethylamino group showed the highest binding affinity. Compound 7 intensely stained neuritic and diffused plaques and

Masahiro Ono; Mamoru Haratake; Morio Nakayama; Yoshikazu Kaneko; Koichi Kawabata; Hiroshi Mori; Mei-Ping Kung; Hank F. Kung

2005-01-01

74

Derivative method for phase retrieval in off-axis quantitative phase imaging.  

PubMed

We present a method for phase retrieval in off-axis interferometric systems. By numerically calculating the transverse 1st and 2nd order derivatives of the interferogram, we show that one can directly retrieve the quantitative phase image, without the need for Fourier or Hilbert transformations. Because of this, the method is significantly faster than the current approaches. We illustrate our method using biological specimen data from three different off-axis quantitative phase imaging techniques. PMID:22660056

Bhaduri, Basanta; Popescu, Gabriel

2012-06-01

75

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

NASA Astrophysics Data System (ADS)

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

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

1997-11-01

76

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

77

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

78

18F-Labeled benzylideneaniline derivatives as new ligands for ?-amyloid plaque imaging in Alzheimer's disease  

Microsoft Academic Search

IntroductionNoninvasive early detection of ?-amyloid (A?) plaques might be useful for the treatment of patients with Alzheimer's disease (AD). We herein describe the synthesis of 18F-labeled benzylideneaniline derivatives using a novel labeling approach for imaging A? plaques in AD patients.

Hak Jeong Lee; Jae Min Jeong; Ganesha Rai; Yun-Sang Lee; Young Soo Chang; Young Ju Kim; Hyung Woo Kim; Dong Soo Lee; Jung Key Chung; Inhee Mook-Jung; Myung Chul Lee

2009-01-01

79

Improving sub-salt imaging using 3D basin model derived velocities  

Microsoft Academic Search

The quality of depth imaging is directly related to the accuracy of the underlying velocity model. In most sub-salt settings, lack of angular illumination severely degrades the resolution and accuracy of velocity information derived from the seismic data itself. A standard approach for building a starting velocity model uses more reliable velocity information outboard of salt which is subsequently extrapolated

R. Stephan Petmecky; Martin L. Albertin; Nick Burke

2009-01-01

80

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

NASA Astrophysics Data System (ADS)

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

Chang, Ni-Bin; Xuan, Zhemin

2011-09-01

81

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

NASA Astrophysics Data System (ADS)

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

Vipparthi, Santosh Kumar; Nagar, Shyam Krishna

2014-09-01

82

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

83

Derivatives  

NSDL National Science Digital Library

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

Bourne, Murray

2008-04-22

84

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

85

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

86

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

Microsoft Academic Search

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

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

2009-01-01

87

Sequential deconvolution input reconstruction  

NASA Astrophysics Data System (ADS)

The reconstruction of inputs from measured outputs is examined. It is shown that the rank deficiency that arises in de-convolving non-collocated arrangements is associated with a kernel that is non-zero only over the part of the time axis where delay from wave propagation prevents uniqueness. Input deconvolution, therefore, follows in the same manner for collocated and non-collocated scenarios, collocation being the special case where the prediction lag can be zero. This paper illustrates that deconvolution carried out on a sliding window is a conditionally stable process and the condition for stability is derived. Examination of the Cramer-Rao Lower Bound of the inputs in frequency shows that the inference model should be formulated such that the spectra of the inputs to be reconstructed, and of the realized measurement noise, are within the model bandwidth. An expression for the error in the reconstructed input as a function of the noise sequence is developed and is used to control the regularization, when regularization is needed. The paper brings attention to the fact that finite dimensional models cannot display true dead time and that failure to recognize this matter has led to algorithms that, in general, propose to violate the physical constraints.

Bernal, Dionisio; Ussia, Alessia

2015-01-01

88

New Data on Lunar Topography Derived from Galileo and Clementine Stereo Images  

NASA Astrophysics Data System (ADS)

We analyzed images, obtained by the Galileo and Clementine spacecraft in 1992 and 1994 using state-of-the-art photogrammetric techniques to derive Digital Terrain Models (DTMs) for selected lunar regions. These regions include: the near-side northern hemisphere, parts of Mare Orientale, and the Alpine Valley. The new topographic data allow us to study the morphology of the Moon, in particular large craters and the multi-ring impact basins in unprecedented detail.

Oberst, J.; Wahlisch, M.; Zhang, W.; Roatsch, T.; Cook, A. C.; Jaumann, R.

1996-03-01

89

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

PubMed

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

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

2014-05-01

90

Empirical Model of Plasmaspheric Densities Derived from the IMAGE RPI Observations  

NASA Astrophysics Data System (ADS)

Using the data gathered during NASA’s IMAGE mission we developed an empirical model of inner plasmasphere (L-shell less than 4) densities. The Radio Plasma Imager (RPI) on board the IMAGE satellite transmitted coded signals and measured the amplitude of the returned echo signals as functions of echo frequency. An inversion algorithm was developed at the Center for Atmospheric Research, University of Massachusetts Lowell, which allows us to derive the plasma density distribution along the magnetic field based on the distinct discrete traces formed by the reflected signals (echoes). By analyzing more than 700 electron density profiles, we determined the dependence of model parameters on the L-shell, magnetic local time, and geomagnetic disturbance indices (Dst or Kp). The developed model is of potential to be a useful tool for the inner magnetosphere research and space weather forecasting.

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

2010-12-01

91

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

92

Surface mineral maps of Afghanistan derived from HyMap imaging spectrometer data, version 2  

USGS Publications Warehouse

This report presents a new version of surface mineral maps derived from HyMap imaging spectrometer data collected over Afghanistan in the fall of 2007. This report also describes the processing steps applied to the imaging spectrometer data. The 218 individual flight lines composing the Afghanistan dataset, covering more than 438,000 square kilometers, were georeferenced to a mosaic of orthorectified Landsat images. The HyMap data were converted from radiance to reflectance using a radiative transfer program in combination with ground-calibration sites and a network of cross-cutting calibration flight lines. The U.S. Geological Survey Material Identification and Characterization Algorithm (MICA) was used to generate two thematic maps of surface minerals: a map of iron-bearing minerals and other materials, which have their primary absorption features at the shorter wavelengths of the reflected solar wavelength range, and a map of carbonates, phyllosilicates, sulfates, altered minerals, and other materials, which have their primary absorption features at the longer wavelengths of the reflected solar wavelength range. In contrast to the original version, version 2 of these maps is provided at full resolution of 23-meter pixel size. The thematic maps, MICA summary images, and the material fit and depth images are distributed in digital files linked to this report, in a format readable by remote sensing software and Geographic Information Systems (GIS). The digital files can be downloaded from http://pubs.usgs.gov/ds/787/downloads/.

Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.

2013-01-01

93

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

94

A neural-based code for computing image velocity from small sets of middle temporal (MT/V5) neuron inputs.  

PubMed

It is still not known how the primate visual system is able to measure the velocity of moving stimuli such as edges and dots. Neurons have been found in the Medial Superior Temporal (MST) area of the primate brain that respond at a rate proportional to the speed of the stimulus but it is not clear how this property is derived from the speed-tuned Middle Temporal (MT) neurons that precede area MST along the visual motion pathway. I show that a population code based on the outputs from a number of MT neurons is susceptible to errors if the MT neurons are tuned to a broad range of spatial frequencies and have receptive fields that span a wide range of sizes. I present a solution that uses the activity of just three MT units within a velocity channel to estimate the velocity using a weighted vector average (centroid) technique. I use a range of velocity channels (1, 2, 4, and 8°/s) with inhibition between them so that only a single channel passes the velocity estimate onto the next stage of processing (MST). I also include a contrast-dependent redundancy-removal stage which provides tighter spatial resolution for the velocity estimates under conditions of high contrast but which trades off spatial compactness for greater sensitivity at low contrast. The new model produces an output signal proportional to the stimulus input velocity (consistent with MST neurons) and its input stages have properties closely tied to those of neurons in areas V1 and MT. PMID:22854102

Perrone, John A

2012-01-01

95

MRI-Derived 3-D-Printed Breast Phantom for Microwave Breast Imaging Validation  

PubMed Central

We propose a 3-D-printed breast phantom for use in preclinical experimental microwave imaging studies. The phantom is derived from an MRI of a human subject; thus, it is anthropomorphic, and its interior is very similar to an actual distribution of fibroglandular tissues. Adipose tissue in the breast is represented by the solid plastic (printed) regions of the phantom, while fibroglandular tissue is represented by liquid-filled voids in the plastic. The liquid is chosen to provide a biologically relevant dielectric contrast with the printed plastic. Such a phantom enables validation of microwave imaging techniques. We describe the procedure for generating the 3-D-printed breast phantom and present the measured dielectric properties of the 3-D-printed plastic over the frequency range 0.5–3.5 GHz. We also provide an example of a suitable liquid for filling the fibroglandular voids in the plastic. PMID:25132808

Burfeindt, Matthew J.; Colgan, Timothy J.; Mays, R. Owen; Shea, Jacob D.; Behdad, Nader; Van Veen, Barry D.; Hagness, Susan C.

2014-01-01

96

Fluorescent carbon nanoparticles derived from natural materials of mango fruit for bio-imaging probes.  

PubMed

Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials. PMID:25375199

Jeong, Chan Jin; Roy, Arup Kumer; Kim, Sung Han; Lee, Jung-Eun; Jeong, Ji Hoon; In, Insik; Park, Sung Young

2014-12-21

97

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

PubMed

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

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

2014-01-15

98

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

SciTech Connect

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

Kundhikanjana, W.

2010-06-02

99

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

PubMed Central

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

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

2012-01-01

100

Fluorescent carbon nanoparticles derived from natural materials of mango fruit for bio-imaging probes  

NASA Astrophysics Data System (ADS)

Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials.Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04805a

Jeong, Chan Jin; Roy, Arup Kumer; Kim, Sung Han; Lee, Jung-Eun; Jeong, Ji Hoon; Insik; Park, Sung Young

2014-11-01

101

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

USGS Publications Warehouse

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

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

2008-01-01

102

Velocity-based cardiac contractility personalization from images using derivative-free optimization.  

PubMed

Model personalization is a key aspect for biophysical models to impact clinical practice, and cardiac contractility personalization from medical images is a major step in this direction. Existing gradient-based optimization approaches show promising results of identifying the maximum contractility from images, but the contraction and relaxation rates are not accounted for. A main reason is the limited choices of objective functions when their gradients are required. For complicated cardiac models, analytical evaluations of gradients are very difficult if not impossible, and finite difference approximations are computationally expensive and may introduce numerical difficulties. By removing such limitations with derivative-free optimization, we found that a velocity-based objective function can properly identify regional maximum contraction stresses, contraction rates, and relaxation rates simultaneously with intact model complexity. Experiments on synthetic data show that the parameters are better identified using the velocity-based objective function than its position-based counterpart, and the proposed framework is insensitive to initial parameters with the adopted derivative-free optimization algorithm. Experiments on clinical data show that the framework can provide personalized contractility parameters which are consistent with the underlying physiologies of the patients and healthy volunteers. PMID:25553554

Wong, Ken C L; Sermesant, Maxime; Rhode, Kawal; Ginks, Matthew; Rinaldi, C Aldo; Razavi, Reza; Delingette, Hervé; Ayache, Nicholas

2015-03-01

103

Novel positively charged nanoparticle labeling for in vivo imaging of adipose tissue-derived stem cells.  

PubMed

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

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

2014-01-01

104

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

105

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

SciTech Connect

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

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

1993-06-01

106

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

107

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

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

108

Labeling Pluripotent Stem Cell-Derived Neural Progenitors with Iron Oxide Particles for Magnetic Resonance Imaging.  

PubMed

Due to the unlimited proliferation capacity and the unique differentiation ability of pluripotent stem cells (PSCs), including both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), large numbers of PSC-derived cell products are in demand for applications in drug screening, disease modeling, and especially cell therapy. In stem cell-based therapy, tracking transplanted cells with magnetic resonance imaging (MRI) has emerged as a powerful technique to reveal cell survival and distribution. This chapter illustrated the basic steps of labeling PSC-derived neural progenitors (NPs) with micron-sized particles of iron oxide (MPIO, 0.86 ?m) for MRI analysis. The protocol described PSC expansion and differentiation into NPs, and the labeling of the derived cells either after replating on adherent surface or in suspension. The labeled cells can be analyzed using in vitro MRI analysis. The methods presented here can be easily adapted for cell labeling in cell processing facilities under current Good Manufacturing Practices (cGMP). The iron oxide-labeled NPs can be used for cellular monitoring of in vitro cultures and in vivo transplantation. PMID:25304204

Sart, Sébastien; Bejarano, Fabian Calixto; Yan, Yuanwei; Grant, Samuel C; Li, Yan

2014-10-11

109

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

110

Noninvasive detection and imaging of molecular markers in live cardiomyocytes derived from human embryonic stem cells.  

PubMed

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. PMID:21190678

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

2011-01-01

111

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

PubMed

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

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

2014-07-01

112

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

PubMed Central

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

Gajewska-Wo?niak, Olga; Skup, Ma?gorzata; Kasicki, Stefan; Ziemli?ska, Ewelina; Czarkowska-Bauch, Julita

2013-01-01

113

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. PMID:21531287

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

2011-01-01

114

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

115

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

116

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

PubMed

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

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

2013-10-24

117

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. PMID:19964029

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

2009-01-01

118

Changes in Thermospheric O/N2 Derived from UVI Auroral Images  

NASA Technical Reports Server (NTRS)

A rigorous test of our understanding of the coupled ionosphere-thermosphere and its response to geomagnetic storms is the ability to reproduce observed storm effects as seen in the ionosphere and neutral atmosphere. The concept of compositional change is central to studies of thermosphere response to storm conditions. In particular, information about compositional change within the highly dynamic auroral region is limited. The Ultraviolet Imager (UVI) is designed to view the full auroral region using five filters to isolate emissions from atomic oxygen (1304 and 1356) and N2 LBH. This spectral resolution allows auroral energy characteristics to be derived by two separate methods from examining ratios of observed intensities (OI 1356/LBHL or LBHS/LBHL). The LBHS:LBHL ratio is typically used as the mean energy diagnostic since the OI 1356 emission is dependent on changes in the atomic oxygen density, and these changes relative to N2 can be large. However, once the mean energy has been specified by the LBH ratio, this variability in OI 1356 emission can be exploited as a direct diagnostic of total atomic oxygen column density. This opens the potential of using UVI images to monitor the temporal and spatial response of thermospheric O to high latitude forcing within the auroral regions. Initial results of this type of analysis will be presented along with discussion of its limitations and capabilities.

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

1997-01-01

119

Synthesis and characterization of water-soluble polythiophene derivatives for cell imaging.  

PubMed

In this work, four water-soluble polythiophene derivatives (PT, PT-DDA, PT-ADA, and PT-ADA-PPR) with different pendant moieties were synthesized via oxidative copolymerization by FeCl3. By increasing the hydrophobic ability of side chain moieties, there is a gradually blue shift for the maximum absorption wavelength and red shift for the maximum emission wavelength, a reducing trend for fluorescence quantum yields, a growing trend for Stokes shift, and an increasing trend for the mean sizes in the order of PT, PT-ADA, and PT-DDA. All the synthesized polymers show low toxicity and good photostability and accumulate in the lysosomes of A549 cells. Furthermore, the introduction of porphyrin group to PT-ADA side chain (PT-ADA-PPR) broadens the absorption and emission ranges of PT-ADA. PT-ADA-PPR could be excited at two different excitation wavelengths (488?nm and 559?nm) and exhibits two emission pathways, and dual-color fluorescence images (orange and red) of PT-ADA-PPR accumulated in A549 cells are observed. Thus, PT-ADA-PPR could be used as an excellent dual-color fluorescent and lysosome-specific imaging material. PMID:25557020

Wang, Fengyan; Li, Meng; Wang, Bing; Zhang, Jiangyan; Cheng, Yongqiang; Liu, Libing; Lv, Fengting; Wang, Shu

2015-01-01

120

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

2007-12-01

121

Synthesis and Characterization of Water-Soluble Polythiophene Derivatives for Cell Imaging  

NASA Astrophysics Data System (ADS)

In this work, four water-soluble polythiophene derivatives (PT, PT-DDA, PT-ADA, and PT-ADA-PPR) with different pendant moieties were synthesized via oxidative copolymerization by FeCl3. By increasing the hydrophobic ability of side chain moieties, there is a gradually blue shift for the maximum absorption wavelength and red shift for the maximum emission wavelength, a reducing trend for fluorescence quantum yields, a growing trend for Stokes shift, and an increasing trend for the mean sizes in the order of PT, PT-ADA, and PT-DDA. All the synthesized polymers show low toxicity and good photostability and accumulate in the lysosomes of A549 cells. Furthermore, the introduction of porphyrin group to PT-ADA side chain (PT-ADA-PPR) broadens the absorption and emission ranges of PT-ADA. PT-ADA-PPR could be excited at two different excitation wavelengths (488 nm and 559 nm) and exhibits two emission pathways, and dual-color fluorescence images (orange and red) of PT-ADA-PPR accumulated in A549 cells are observed. Thus, PT-ADA-PPR could be used as an excellent dual-color fluorescent and lysosome-specific imaging material.

Wang, Fengyan; Li, Meng; Wang, Bing; Zhang, Jiangyan; Cheng, Yongqiang; Liu, Libing; Lv, Fengting; Wang, Shu

2015-01-01

122

Tumor Imaging and Targeting Potential of an Hsp70-Derived 14-Mer Peptide  

PubMed Central

Background We have previously used a unique mouse monoclonal antibody cmHsp70.1 to demonstrate the selective presence of a membrane-bound form of Hsp70 (memHsp70) on a variety of leukemia cells and on single cell suspensions derived from solid tumors of different entities, but not on non-transformed cells or cells from corresponding ’healthy‘ tissue. This antibody can be used to image tumors in vivo and target them for antibody-dependent cellular cytotoxicity. Tumor-specific expression of memHsp70 therefore has the potential to be exploited for theranostic purposes. Given the advantages of peptides as imaging and targeting agents, this study assessed whether a 14-mer tumor penetrating peptide (TPP; TKDNNLLGRFELSG), the sequence of which is derived from the oligomerization domain of Hsp70 which is expressed on the cell surface of tumor cells, can also be used for targeting membrane Hsp70 positive (memHsp70+) tumor cells, in vitro. Methodology/Principal Findings The specificity of carboxy-fluorescein (CF-) labeled TPP (TPP) to Hsp70 was proven in an Hsp70 knockout mammary tumor cell system. TPP specifically binds to different memHsp70+ mouse and human tumor cell lines and is rapidly taken up via endosomes. Two to four-fold higher levels of CF-labeled TPP were detected in MCF7 (82% memHsp70+) and MDA-MB-231 (75% memHsp70+) cells compared to T47D cells (29% memHsp70+) that exhibit a lower Hsp70 membrane positivity. After 90 min incubation, TPP co-localized with mitochondrial membranes in memHsp70+ tumors. Although there was no evidence that any given vesicle population was specifically localized, fluorophore-labeled cmHsp70.1 antibody and TPP preferentially accumulated in the proximity of the adherent surface of cultured cells. These findings suggest a potential association between membrane Hsp70 expression and cytoskeletal elements that are involved in adherence, the establishment of intercellular synapses and/or membrane reorganization. Conclusions/Significance This study demonstrates the specific binding and rapid internalization of TPP by tumor cells with a memHsp70+ phenotype. TPP might therefore have potential for targeting and imaging the large proportion of tumors (?50%) that express memHsp70. PMID:25165986

Oellinger, Rupert; Breuninger, Stephanie; Rad, Roland; Pockley, Alan G.; Multhoff, Gabriele

2014-01-01

123

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

124

Imaging-based chemical screens using normal and glioma-derived neural stem cells.  

PubMed

The development of optimal culture methods for embryonic, tissue and cancer stem cells is a critical foundation for their application in drug screening. We previously described defined adherent culture conditions that enable expansion of human radial glia-like fetal NS (neural stem) cells as stable cell lines. Similar protocols proved effective in the establishment of tumour-initiating stem cell lines from the human brain tumour glioblastoma multiforme, which we termed GNS (glioma NS) cells. Others have also recently derived more primitive human NS cell lines with greater neuronal subtype differentiation potential than NS cells, which have similarities to the early neuroepithelium, named NES (neuroepithelial stem) cells. In the present paper, we discuss the utility of these cells for chemical screening, and describe methods for a simple high-content live-image-based platform. We report the effects of a panel of 160 kinase inhibitors (Inhibitor Select I and II; Calbiochem) on NES cells, identifying three inhibitors of ROCK (Rho-associated kinase) as promoting the expansion of NES cell cultures. For the GNS cells, we screened a panel of 1000 compounds and confirmed our previous finding of a cytotoxic effect of modulators of neurotransmitter signalling pathways. These studies provide a framework for future higher-throughput screens. PMID:20659005

Danovi, Davide; Falk, Anna; Humphreys, Peter; Vickers, Richard; Tinsley, Jon; Smith, Austin G; Pollard, Steven M

2010-08-01

125

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

PubMed

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

Gaonkar, Bilwaj; Davatzikos, Christos

2012-01-01

126

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

PubMed Central

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

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

2009-01-01

127

A COMPACT IMAGE MAGNIFICATION METHOD WITH PRESERVATION OF PREFERENTIAL COMPONENTS  

E-print Network

in input images. We show that, by choosing the edge enhancement components as the preferen- tial components of computation. Index Terms-- Image enhancement, image reconstruc- tion, interpolation 1. INTRODUCTION Image], spatial neural networks [4], and sparse derivative prior [5]. These approaches use plenty of appropriate

Condat, Laurent

128

Total Bolus Extraction Method Improves Arterial Image Quality in Dynamic CTAs Derived from Whole-Brain CTP Data  

PubMed Central

Background and Purposes. The 320-detector row CT scanner enables visualization of whole-brain hemodynamic information (dynamic CT angiography (CTA) derived from CT perfusion scans). However, arterial image quality in dynamic CTA (dCTA) is inferior to arterial image quality in standard CTA. This study evaluates whether the arterial image quality can be improved by using a total bolus extraction (ToBE) method. Materials and Methods. DCTAs of 15 patients, who presented with signs of acute cerebral ischemia, were derived from 320-slice CT perfusion scans using both the standard subtraction method and the proposed ToBE method. Two neurointerventionalists blinded to the scan type scored the arterial image quality on a 5-point scale in the 4D dCTAs in consensus. Arteries were divided into four categories: (I) large extradural, (II) intradural (large, medium, and small), (III) communicating arteries, and (IV) cerebellar and ophthalmic arteries. Results. Quality of extradural and intradural arteries was significantly higher in the ToBE dCTAs than in the standard dCTAs (extradural P = 0.001, large intradural P < 0.001, medium intradural P < 0.001, and small intradural P < 0.001). Conclusion. The 4D dCTAs derived with the total bolus extraction (ToBE) method provide hemodynamic information combined with improved arterial image quality as compared to standard 4D dCTAs. PMID:25136600

Ghariq, Elyas; Mendrik, Adriënne M.; Willems, Peter W. A.; Joemai, Raoul M. S.; Ghariq, Eidrees; Vonken, Evert-jan; van Osch, Matthias J. P.; van Walderveen, Marianne A. A.

2014-01-01

129

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

130

Application of the mean intensity of the second derivative in evaluating the speckle patterns in digital image correlation  

NASA Astrophysics Data System (ADS)

In this work, the mean intensity of the second derivative of speckle pattern was used to quantify the quality of the speckle patterns for digital image correlation. Numerical experimental studies were performed to justify the correctness and effectiveness of this new global parameter. The results indicate that the measured displacement error was related to the mean intensity of the second derivative of the speckle patterns when they had equal mean intensity gradients. The results also indicate that the measurement accuracy was affected by both the mean intensity gradient and the mean intensity of the second derivative. Therefore, high quality speckle patterns should have a large mean intensity gradient and a small mean intensity of the second derivative.

Yu, Hai; Guo, Rongxin; Xia, Haiting; Yan, Feng; Zhang, Yubo; He, Tianchun

2014-09-01

131

Synthesis, Radiolabeling and Biological Evaluation of 99mTc-labeled Deoxyglucose Derivatives for Molecular Imaging  

PubMed Central

Two deoxyglucose (DG) derivatives, (?,?)-2-deoxy-2-amino(ethylcarbamate)-D-glucose (ECB-DG) and (?,?)-2-deoxy-2-amino(1,2-dihydroxypropyl)-D-glucose (DHP-DG), were synthesized and radiolabeled successfully with [99mTc(H2O)3(CO)3]+ complex. [99mTc]-ECB-DG and [99mTc]-DHP-DG complexes were prepared (96% and 93% radiochemical purities respectively) by using 46 mCi of Na99mTcO4 in 1 mL saline. Radio-HPLC analysis of [99mTc]- ECB-DG at pH = 7.4, revealed that labeling with 99mTc leads to formation of one radiochemical species with tR = 381 second. Three radiochemical species, Na99mTcO4, [99mTc]-DHP-DG and [99mTc(H2O)3(CO)3]+ complexes with tR = 342 sec, tR = 567 sec and tR = 1586 sec respectively, were obtained when [99mTc]-DHP-DG complex evaluated by HPLC. Biodistribution of two complexes were studied on normal mice at 10, 30 and 60 min post-injections. Compared to the 18F-FDG, [99mTc]-ECB-DG displayed a 2.8-fold reduction in brain uptake (1.7 ± 0.2 versus 0.61% ± 0.09) ,whereas [99mTc]-DHP-DG just showed 1.9-fold reduction in heart uptake (2.2 ± 0.05 towards 1.16±0.10) at 1 h post-injection. On the basis of our results, it seems that ECB-DG and DHP-DG analogues could be used as brain and heart imaging agent respectively. PMID:24250633

Sadeghzadeh, Masoud; Charkhlooiea, Ghorbanali; Johari Daha, Fariba

2013-01-01

132

Glacier topography and elevation changes derived from Pléiades sub-meter stereo images  

NASA Astrophysics Data System (ADS)

In response to climate change, most glaciers are losing mass and hence contribute to sea-level rise. Repeated and accurate mapping of their surface topography is required to estimate their mass balance and to extrapolate/calibrate sparse field glaciological measurements. In this study we evaluate the potential of sub-meter stereo imagery from the recently launched Pléiades satellites to derive digital elevation models (DEMs) of glaciers and their elevation changes. Our five evaluation sites, where nearly simultaneous field measurements were collected, are located in Iceland, the European Alps, the central Andes, Nepal and Antarctica. For Iceland, the Pléiades DEM is also compared to a lidar DEM. The vertical biases of the Pléiades DEMs are less than 1 m if ground control points (GCPs) are used, but reach up to 7 m without GCPs. Even without GCPs, vertical biases can be reduced to a few decimetres by horizontal and vertical co-registration of the DEMs to reference altimetric data on ice-free terrain. Around these biases, the vertical precision of the Pléiades DEMs is ±1 m and even ±0.5 m on the flat glacier tongues (1? confidence level). Similar precision levels are obtained in the accumulation areas of glaciers and in Antarctica. We also demonstrate the high potential of Pléiades DEMs for measuring seasonal, annual and multi-annual elevation changes with an accuracy of 1 m or better if cloud-free images are available. The negative region-wide mass balances of glaciers in the Mont-Blanc area (-1.04 ± 0.23 m a-1 water equivalent, w.e.) are revealed by differencing Satellite pour l'Observation de la Terre 5 (SPOT 5) and Pléiades DEMs acquired in August 2003 and 2012, confirming the accelerated glacial wastage in the European Alps.

Berthier, E.; Vincent, C.; Magnússon, E.; Gunnlaugsson, Á. Þ.; Pitte, P.; Le Meur, E.; Masiokas, M.; Ruiz, L.; Pálsson, F.; Belart, J. M. C.; Wagnon, P.

2014-12-01

133

Tensor-based image diffusions derived from generalizations of the Total Variation and Beltrami Functionals  

Microsoft Academic Search

We introduce a novel functional for vector-valued images that generalizes several variational methods, such as the Total Variation and Beltrami Functionals. This functional is based on the structure tensor that describes the geometry of image structures within the neighborhood of each point. We first generalize the Beltrami functional based on the image patches and using embeddings in high dimensional spaces.

Anastasios Roussos; Petros Maragos

2010-01-01

134

Bilinearity in Spatiotemporal Integration of Synaptic Inputs  

PubMed Central

Neurons process information via integration of synaptic inputs from dendrites. Many experimental results demonstrate dendritic integration could be highly nonlinear, yet few theoretical analyses have been performed to obtain a precise quantitative characterization analytically. Based on asymptotic analysis of a two-compartment passive cable model, given a pair of time-dependent synaptic conductance inputs, we derive a bilinear spatiotemporal dendritic integration rule. The summed somatic potential can be well approximated by the linear summation of the two postsynaptic potentials elicited separately, plus a third additional bilinear term proportional to their product with a proportionality coefficient . The rule is valid for a pair of synaptic inputs of all types, including excitation-inhibition, excitation-excitation, and inhibition-inhibition. In addition, the rule is valid during the whole dendritic integration process for a pair of synaptic inputs with arbitrary input time differences and input locations. The coefficient is demonstrated to be nearly independent of the input strengths but is dependent on input times and input locations. This rule is then verified through simulation of a realistic pyramidal neuron model and in electrophysiological experiments of rat hippocampal CA1 neurons. The rule is further generalized to describe the spatiotemporal dendritic integration of multiple excitatory and inhibitory synaptic inputs. The integration of multiple inputs can be decomposed into the sum of all possible pairwise integration, where each paired integration obeys the bilinear rule. This decomposition leads to a graph representation of dendritic integration, which can be viewed as functionally sparse. PMID:25521832

Li, Songting; Liu, Nan; Zhang, Xiao-hui; Zhou, Douglas; Cai, David

2014-01-01

135

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

136

A coumarin derivative as a fluorogenic glycoproteomic probe for biological imaging.  

PubMed

Fluorescence imaging in living cells is typically carried out using a functionalized fluorescent dye. But it often causes strong background noise under many conditions where washing is not applicable. Here, we report on a coumarin based fluorogenic probe, which can be used as a bioorthogonal-labeling tool for glycoproteins. The results indicated that the probe was able to image glycoproteins in living cells and it may also be suitable for intracellular imaging. PMID:24281692

Rong, Lei; Liu, Li-Han; Chen, Si; Cheng, Han; Chen, Chang-Sheng; Li, Ze-Yong; Qin, Si-Yong; Zhang, Xian-Zheng

2014-01-21

137

Average coherence image derived observations over an urban area: the case of Athens city  

NASA Astrophysics Data System (ADS)

In the present study coherence observations, in relation to the land-cover type, obtained using 20 C-band ERS SAR Single Look Complex (SLC) VV-polarization images acquired in descending mode over the metropolitan area of Athens covering the period 1992-1999 are presented. A straightforward approach using a single master SAR image on which the other images are mapped was adopted ensuring perfect registration of the interferometric results. After generating single coherence images, with temporal separation varying between 138 and 1335 days, an averaging procedure followed leading to the average coherence image. In order to identify and statistically interpret the properties of selected land cover types in terms of average degree of coherence, very high resolution QuickBird imagery was downloaded from Google Earth environment. The final geocoding of the average coherence image has been improved using common features in the coherence image and the very high-resolution QuickBird image. Overlay of coherence product on the QuickBird image allows correlating the level of coherence with characteristics and properties of the urban shell. As urban areas are considered of high coherence, observations of this type permit to investigate and evaluate their phase stability in details.

Parcharidis, I.; Foumelis, M.; Kourkouli, P.

2007-10-01

138

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

139

Automatic derivation of initial match points for paired digital images of skin.  

PubMed

Computerized matching of skin images has been suggested as a means of screening for changes indicative of malignant melanoma. Matching or "registering" each lesion in a pair of images plays an important role in this process. Point-pattern matching algorithms based upon correlation or geometric transformations of the image pairs have been shown to be effective for this registration but require knowledge of one or more "initial match" points which are known to be the same on both images. A method is described for automatically finding these initial match points with a high degree of success. Our algorithm uses the so-called "Gabriel graph" representation of the paired images to select sets of probable matching points. Performance of the algorithm has been measured in realistic trials, using images of patients with large numbers of pigmented lesions. Results show that the single best match chosen is correct greater than 99% of the time, while over 93% of the first three consecutive matches will be chosen correctly. It is likely that these results can be improved through the use of additional nonpositional information or additional image processing. PMID:1623497

White, R G; Perednia, D A

1992-01-01

140

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

Microsoft Academic Search

High-resolution magnetic resonance imaging (MRI) of trabecular bone combined with quantitative image analysis represents a\\u000a powerful technique to gain insight into trabecular bone micro-architectural derangements in osteoporosis and osteoarthritis.\\u000a The increased signal-to-noise ratio of ultra high-field MR (?7 Tesla) permits images to be obtained with higher resolution\\u000a and\\/or decreased scan time compared to scanning at 1.5\\/3T. In this small feasibility

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

2011-01-01

141

Three-dimensional image technology in forensic anthropology: Assessing the validity of biological profiles derived from CT-3D images of the skeleton  

NASA Astrophysics Data System (ADS)

This project explores the reliability of building a biological profile for an unknown individual based on three-dimensional (3D) images of the individual's skeleton. 3D imaging technology has been widely researched for medical and engineering applications, and it is increasingly being used as a tool for anthropological inquiry. While the question of whether a biological profile can be derived from 3D images of a skeleton with the same accuracy as achieved when using dry bones has been explored, bigger sample sizes, a standardized scanning protocol and more interobserver error data are needed before 3D methods can become widely and confidently used in forensic anthropology. 3D images of Computed Tomography (CT) scans were obtained from 130 innominate bones from Boston University's skeletal collection (School of Medicine). For each bone, both 3D images and original bones were assessed using the Phenice and Suchey-Brooks methods. Statistical analysis was used to determine the agreement between 3D image assessment versus traditional assessment. A pool of six individuals with varying experience in the field of forensic anthropology scored a subsample (n = 20) to explore interobserver error. While a high agreement was found for age and sex estimation for specimens scored by the author, the interobserver study shows that observers found it difficult to apply standard methods to 3D images. Higher levels of experience did not result in higher agreement between observers, as would be expected. Thus, a need for training in 3D visualization before applying anthropological methods to 3D bones is suggested. Future research should explore interobserver error using a larger sample size in order to test the hypothesis that training in 3D visualization will result in a higher agreement between scores. The need for the development of a standard scanning protocol focusing on the optimization of 3D image resolution is highlighted. Applications for this research include the possibility of digitizing skeletal collections in order to expand their use and for deriving skeletal collections from living populations and creating population-specific standards. Further research for the development of a standard scanning and processing protocol is needed before 3D methods in forensic anthropology are considered as reliable tools for generating biological profiles.

Garcia de Leon Valenzuela, Maria Julia

142

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

PubMed

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. PMID:21221706

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

2011-06-01

143

Design, synthesis, and structure–activity relationship of novel thiophene derivatives for ?-amyloid plaque imaging  

Microsoft Academic Search

Novel 2,5-diphenylthiophene derivatives were synthesized and structure activity relationship with regard to A? plaque binding was studied. Binding affinities of these compounds were found to range from 3.9 to >1000nM, depending on the substitution patterns on the phenyl ring. The fluoroethyl-substituted thiophene derivatives showed excellent binding affinities. These compounds may be useful for the development of novel PET tracers for

Rajesh Chandra; Mei-Ping Kung; Hank F. Kung

2006-01-01

144

Multi-thread input  

Microsoft Academic Search

Implementors of interactive computer workstations have tended to shy away from making several devices simultaneously available to a user of their systems. The principal reason for this reluctance has been the difficulty faced by an application program in analyzing the several streams of input that such a configuration would present. Recently systems have been developed that support such multi-thread input.

P P Tanner

1987-01-01

145

MDS MIC Catalog Inputs  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

146

Multispectral MWIR image classification using filters derived from independent component analysis  

NASA Astrophysics Data System (ADS)

It is known that spectral-spatial ICA basis functions of visible color images are similar to some processing elements in the human visual systems in that they resemble Gabor filters and show color opponencies. In this research we study combined spectral-spatial ICA basis functions of multispectral MWIR images. These ICA spectral-spatial basis functions are then used as filters to extract features from multispectral MWIR images. It is hypothesized that learning the added dimension of spectral information along with spatial characteristics of basis functions using ICA improves classification performance for multispectral MWIR images. The images are captured in the 3.0 - 5.0um, 3.7 - 4.2um and 4.0 - 4.5um bands using a multispectral MWIR camera. The phase relationship between the basis functions indicate how the extracted features from the different spectral band images can be combined. We use classification performance to compare features obtained by filtering using multispectral ICA basis functions, multispectral PCA basis functions and opponent Gabor filters.

Chari, Srikant; Halford, Carl; Jacobs, Eddie; Robinson, Aaron

2007-04-01

147

The Scale-height Of Optical-depth In Valles Marineris As Derived From Shadows In HRSC Images  

NASA Astrophysics Data System (ADS)

The optical depth of the Martian atmosphere can be estimated from the brightness of shadows with the so called "shadow method". We investigated the accuracy of this method by analyzing a set of stereo and color images observed on July 21, 2005 with the High Resolution Stereo Camera of the Mars-Express orbiter. The images show part of Valles Marineris during late afternoon and contain numerous shadows. Whereas the analyzed regions span height differences of about ten kilometers, we could study the relation between altitude and shadow method measurements. If the optical depth and gas-pressure have similar scale heights, then the accuracy with which our measurements can reproduce the pressure-scale-height tells about the accuracy of the shadow method. Various GCMs suggest a local pressure scale height of around 13 km at that moment, while the red and the five panchromatic stereo images all yielded similar scale heights with an average of 12.2 ± 0.7 km. Thus, in the color of the panchromatics (yellow to red) and in red the shadow method yielded good results. The scale height derived from the NIR image is too low: 10.6 ± 0.4 km, we speculate that this is an effect from airborne dust particles that are on average larger in the lower than in the higher atmosphere. The scale heights that were derived from blue and green images were unrealistically high: 17.0 ± 0.7 km and 14.5 ± 0.5 km respectively. This may be caused by thin white high altitude hazes, or indicate that the accuracy of the shadow method varies with optical depth in these colors.

Hoekzema, Nick; Garcia-Comas, M.; Petrova, E. V.; Stenzel, O. J.; Markiewicz, W. J.; Gwinner, K.; Keller, H. U.

2009-09-01

148

Dynamic susceptibility contrast MRI with localized arterial input functions.  

PubMed

Compared to gold-standard measurements of cerebral perfusion with positron emission tomography using H(2)[(15)O] tracers, measurements with dynamic susceptibility contrast MR are more accessible, less expensive, and less invasive. However, existing methods for analyzing and interpreting data from dynamic susceptibility contrast MR have characteristic disadvantages that include sensitivity to incorrectly modeled delay and dispersion in a single, global arterial input function. We describe a model of tissue microcirculation derived from tracer kinetics that estimates for each voxel a unique, localized arterial input function. Parameters of the model were estimated using Bayesian probability theory and Markov-chain Monte Carlo, circumventing difficulties arising from numerical deconvolution. Applying the new method to imaging studies from a cohort of 14 patients with chronic, atherosclerotic, occlusive disease showed strong correlations between perfusion measured by dynamic susceptibility contrast MR with localized arterial input function and perfusion measured by quantitative positron emission tomography with H(2)[(15)O]. Regression to positron emission tomography measurements enabled conversion of dynamic susceptibility contrast MR to a physiologic scale. Regression analysis for localized arterial input function gave estimates of a scaling factor for quantitation that described perfusion accurately in patients with substantial variability in hemodynamic impairment. PMID:20432301

Lee, John J; Bretthorst, G Larry; Derdeyn, Colin P; Powers, William J; Videen, Tom O; Snyder, Abraham Z; Markham, Joanne; Shimony, Joshua S

2010-05-01

149

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. PMID:22073204

Niu, Ran; Skliar, Mikhail

2011-01-01

150

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

151

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

PubMed Central

Parametric imaging maps (PIM’s) derived from digital subtraction angiography (DSA) for the cerebral arterial flow assessment in clinical settings have been proposed, but experiments have yet to determine the reliability of such studies. For this study, we have observed the effects of different injection techniques on PIM’s. A flow circuit set to physiologic conditions was created using an internal carotid artery phantom. PIM’s were derived for two catheter positions, two different contrast bolus injection volumes (5ml and 10 ml), and four injection rates (5, 10, 15 and 20 ml/s). Using a gamma variate fitting approach, we derived PIM’s for mean-transit-time (MTT), time-to-peak (TTP) and bolus-arrivaltime (BAT). For the same injection rates, a larger bolus resulted in an increased MTT and TTP, while a faster injection rate resulted in a shorter MTT, TTP, and BAT. In addition, the position of the catheter tip within the vasculature directly affected the PIM. The experiment showed that the PIM is strongly correlated with the injection conditions, and, therefore, they have to be interpreted with caution. PIM images must be taken from the same patient to be able to be meaningfully compared. These comparisons can include pre- and post-treatment images taken immediately before and after an interventional procedure or simultaneous arterial flow comparisons through the left and right cerebral hemispheres. Due to the strong correlation between PIM and injection conditions, this study indicates that this assessment method should be used only to compare flow changes before and after treatment within the same patient using the same injection conditions. PMID:25302010

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

2014-01-01

152

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

SciTech Connect

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

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

2013-04-01

153

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

154

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

PubMed

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

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

2013-01-01

155

Synthesis and In Vitro Evaluation of Oxindole Derivatives as Potential Radioligands for 5-HT7 Receptor Imaging with PET  

PubMed Central

The most recently discovered serotonin (5-HT) receptor subtype, 5-HT7, is considered to be associated with several CNS disorders. Noninvasive in vivo positron emission tomography (PET) studies of cerebral 5-HT7 receptors could provide a significant advance in the understanding of the neurobiology and eventual dysfunctions of the 5-HT7 receptor. To date, no appropriate 5-HT7 receptor PET ligand has been developed. Here, we modified known 5-HT7 selective phenylpiperazinyl-butyloxindole derivatives so that they may be labeled either with carbon-11 or fluorine-18. A set of potential 5-HT7 ligands for PET molecular imaging was successfully synthesized. Two compounds (10 and 14) were tested against a range of targets. Both compounds display a promising in vitro profile with respect to PET imaging of the 5-HT7 receptor in thalamic regions. PMID:23259035

2012-01-01

156

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

PubMed Central

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

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

2013-01-01

157

Time-lapse Imaging of Primary Preneoplastic Mammary Epithelial Cells Derived from Genetically Engineered Mouse Models of Breast Cancer  

PubMed Central

Time-lapse imaging can be used to compare behavior of cultured primary preneoplastic mammary epithelial cells derived from different genetically engineered mouse models of breast cancer. For example, time between cell divisions (cell lifetimes), apoptotic cell numbers, evolution of morphological changes, and mechanism of colony formation can be quantified and compared in cells carrying specific genetic lesions. Primary mammary epithelial cell cultures are generated from mammary glands without palpable tumor. Glands are carefully resected with clear separation from adjacent muscle, lymph nodes are removed, and single-cell suspensions of enriched mammary epithelial cells are generated by mincing mammary tissue followed by enzymatic dissociation and filtration. Single-cell suspensions are plated and placed directly under a microscope within an incubator chamber for live-cell imaging. Sixteen 650 ?m x 700 ?m fields in a 4x4 configuration from each well of a 6-well plate are imaged every 15 min for 5 days. Time-lapse images are examined directly to measure cellular behaviors that can include mechanism and frequency of cell colony formation within the first 24 hr of plating the cells (aggregation versus cell proliferation), incidence of apoptosis, and phasing of morphological changes. Single-cell tracking is used to generate cell fate maps for measurement of individual cell lifetimes and investigation of cell division patterns. Quantitative data are statistically analyzed to assess for significant differences in behavior correlated with specific genetic lesions. PMID:23425702

Nakles, Rebecca E.; Millman, Sarah L.; Cabrera, M. Carla; Johnson, Peter; Mueller, Susette; Hoppe, Philipp S.; Schroeder, Timm; Furth, Priscilla A.

2013-01-01

158

Preclinical evaluation of a CXCR4-specific (68)Ga-labelled TN14003 derivative for cancer PET imaging.  

PubMed

Molecular imaging is an ideal platform for non-invasive detection and assessment of cancer. In recent years, the targeted imaging of CXCR4, a chemokine receptor that has been associated with tumour metastasis, has become an area of intensive research. In our pursuit of a CXCR4-specific radiotracer, we designed and synthesised a novel derivative of the CXCR4 peptidic antagonist TN14003, CCIC16, which is amenable to radiolabelling by chelation with a range of PET and SPECT radiometals, such as (68)Ga, (64)Cu and (111)In as well as (18)F (Al(18)F). Potent in vitro binding affinity and inhibition of signalling-dependent cell migration by unlabelled CCIC16 were confirmed by a threefold uptake in CXCR4-over-expressing cells compared to their isogenic counterparts. Furthermore, in vivo experiments demonstrated the favourable pharmacokinetic properties of the (68)Ga-labelled tracer (68)Ga-CCIC16, along with its CXCR4-specific accumulation in tissues with desirable contrast (tumour-to-muscle ratio: 9.5). The specificity of our tracer was confirmed by blocking experiments. Taking into account the attractive intrinsic PET imaging properties of (68)Ga, the comprehensive preclinical evaluation presented here suggests that (68)Ga-CCIC16 is a promising PET tracer for the specific imaging of CXCR4-expressing tumours. PMID:24365390

George, Guillaume P C; Stevens, Elizabeth; Åberg, Ola; Nguyen, Quang-Dé; Pisaneschi, Federica; Spivey, Alan C; Aboagye, Eric O

2014-01-15

159

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

160

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

Microsoft Academic Search

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

A. Fitzgerald; H. Griffiths

1998-01-01

161

Radiolabeled mannosylated dextran derivatives bearing an NIR-fluorophore for sentinel lymph node imaging.  

PubMed

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

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

2014-11-19

162

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

163

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

Microsoft Academic Search

AFM-compatible near-field microwave impedance microscope (MIM), capable of measuring local complex dielectric constant with 100 nm resolution, is used to study graphene in different modalities, with a hierarchy of electrical properties. The low-conductivity graphite oxide and its derivatives show significant electronic inhomogeneity. In the low DC resistance chemically exfoliated graphene sheets, the residual defects lead to appreciable electronics inhomogeneity. In

Worasom Kundhikanjana; Keji Lai; Hailiang Wang; Hongjie Dai; Michael Kelly; Zhi-Xun Shen

2010-01-01

164

Synthesis and biological evaluation of indole-chalcone derivatives as ?-amyloid imaging probe  

Microsoft Academic Search

A series of chaclone derivatives containing an indole moiety were evaluated in competitive binding assays with A?1-42 aggregates versus [125I]IMPY. The affinity of these compounds ranged from 4.46 to >1008nM, depending on the substitution on the phenyl ring. Fluorescent staining in vitro showed that one compound with a N,N-dimethylamino group intensely stained A? plaques within brain sections of AD transgenic

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

2011-01-01

165

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

PubMed

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

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

2014-01-28

166

Visualizing 2D Probability Distributions from Satellite Image-Derived Data  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

167

Synthesis of a Cu2+-Selective Probe Derived from Rhodamine and Its Application in Cell Imaging  

PubMed Central

A new fluorescent probe P based on rhodamine for Cu2+ was synthesized and characterized. The new probe P showed high selectivity to Cu2+ over other tested metal ions. With optimal conditions, the proposed probe P worked in a wide linear range of 1.0 × 10?6?1.0 × 10?5 M with a detection limit of 3.3 × 10?7 M Cu2+ in ethanol-water solution (9:1, v:v, 20 mM HEPES, pH 7.0). Furthermore, it has been used for imaging of Cu2+ in living cells with satisfying results. PMID:25397918

Yu, Chunwei; Wen, Yingying; Zhang, Jun

2014-01-01

168

Synthesis of a cu2+-selective probe derived from rhodamine and its application in cell imaging.  

PubMed

A new fluorescent probe P based on rhodamine for Cu2+ was synthesized and characterized. The new probe P showed high selectivity to Cu2+ over other tested metal ions. With optimal conditions, the proposed probe P worked in a wide linear range of 1.0 × 10-6-1.0 × 10-5 M with a detection limit of 3.3 × 10-7 M Cu2+ in ethanol-water solution (9:1, v:v, 20 mM HEPES, pH 7.0). Furthermore, it has been used for imaging of Cu2+ in living cells with satisfying results. PMID:25397918

Yu, Chunwei; Wen, Yingying; Zhang, Jun

2014-01-01

169

Labeling human embryonic stem-cell-derived cardiomyocytes for tracking with MR imaging  

Microsoft Academic Search

Background  Human embryonic stem cells (hESC) can generate cardiomyocytes (CM), which offer promising treatments for cardiomyopathies\\u000a in children. However, challenges for clinical translation result from loss of transplanted cell from target sites and high\\u000a cell death. An imaging technique that noninvasively and repetitively monitors transplanted hESC-CM could guide improvements\\u000a in transplantation techniques and advance therapies.\\u000a \\u000a \\u000a \\u000a \\u000a Objective  To develop a clinically applicable labeling

Rosalinda T. Castaneda; Sophie Boddington; Tobias D. Henning; Mike Wendland; Lydia Mandrussow; Siyuan Liu; Heike Daldrup-Link

170

Fluorescent labelling of DNA on superparamagnetic nanoparticles by a perylene bisimide derivative for cell imaging.  

PubMed

N,N'-Bis[tris-(2-aminoethyl) amine]-3,4,9,10-perylenetetracarboxylic diimide (PBI-TRIS), nonfluorescent dye was used to fluorescent labelling of DNA. For this aim, (3-aminopropyl) triethoxysilane (APTS) modified superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized to provide a suitable surface for binding of DNA. Amine functionalized nanoparticles showed a high immobilization capacity (82.70%) at 25mg of nanoparticle concentration for Calf thymus DNA. Binding capacity of PBI-TRIS to DNA-SPION was also found as 1.93?M on 25mg of nanoparticles by using UV-vis spectroscopy. Binding of PBI-TRIS to DNA onto nanoparticles was also characterized by scanning electron microscopy and infrared spectroscopy. The confocal images of PBI-TRIS labelled DNA-SPION and breast cells were taken at 488 and 561.7nm of excitation wavelengths. Cell image was also compared with a commercial dye, DAPI at 403.7nm of excitation wavelength. Results showed that PBI-TRIS can be used for cell staining. PMID:25579900

Maltas, Esra; Malkondu, Sait; Uyar, Pembegul; Ozmen, Mustafa

2015-03-01

171

Input Decimated Ensembles  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

172

Physical and Chemical Properties of Cometary Dust Derived from Modeling of Mid-Infrared Imaging Observations  

NASA Astrophysics Data System (ADS)

Significant constraints are placed on the physical and chemical properties of cometary dust grains by analyzing mid-infrared imaging data obtained with the UCSD 'Golden Gopher' infrared camera at the 1.5-meter telescope at Mt. Lemmon Observatory. Dust grains are modeled as Mie spheres composed of either amorphous olivine (a silicate glass) or an organic residue mixture, and the results show that the optical characteristics of the two materials are quite different. The equilibrium temperatures of organic grains are much higher than for olivine grains (for the same size grains), and their respective mid-infrared emission properties are rather distinct. The results of these calculations are applied to multi-wavelength imaging of comets C/1996 B2 Hyakutake and C/1995 O1 Hale-Bopp, and it is found that the observed thermal emission from these comets can be duplicated by emission from a mixture of olivine and organic grains. For Hyakutake, the best fit to the data is achieved using 1 ?m olivine grains and 7 ?m organic grains, with an olivine mass fraction of 10%. For Hale-Bopp the predominant grain radii are 1 ?m for olivine and 2.5 ?m for organics, with a much higher olivine mass fraction of 40%. Dynamical simulations are performed using these grains in order to interpret 11.7 ?m images of comet 109P/Swift-Tuttle taken over a three week period in November 1992. The nucleus of the comet is found to be in a simple rotational state (at least over short time-scales), undergoing prograde rotation with an obliquity of 45o± 10o relative to its orbital plane. At perihelion, the angle between the rotation axis and the Sun is 115o± 10o, so that the 'Southern' hemisphere of the comet is generally sunward. Assuming a spherical nucleus rotating with a period of 67.5 hours, three major emission regions on the surface are identified from the recurring jet pattern. The observed dust morphology is best simulated using a grain size distribution of the form f(a)~ a-? for grain radii in the range 0.6 < a < 10/ ?m with ? = 2.5 ± 0.5, and using jets whose opening angles are between 50o and 80o.

Sarmecanic, James Richard

1997-12-01

173

Establishing the resting state default mode network derived from functional magnetic resonance imaging tasks as an endophenotype: A twins study.  

PubMed

The resting state default mode network (DMN) has been shown to characterize a number of neurological and psychiatric disorders. Evidence suggests an underlying genetic basis for this network and hence could serve as potential endophenotype for these disorders. Heritability is a defining criterion for endophenotypes. The DMN is measured either using a resting-state functional magnetic resonance imaging (fMRI) scan or by extracting resting state activity from task-based fMRI. The current study is the first to evaluate heritability of this task-derived resting activity. 250 healthy adult twins (79 monozygotic and 46 dizygotic same sex twin pairs) completed five cognitive and emotion processing fMRI tasks. Resting state DMN functional connectivity was derived from these five fMRI tasks. We validated this approach by comparing connectivity estimates from task-derived resting activity for all five fMRI tasks, with those obtained using a dedicated task-free resting state scan in an independent cohort of 27 healthy individuals. Structural equation modeling using the classic twin design was used to estimate the genetic and environmental contributions to variance for the resting-state DMN functional connectivity. About 9-41% of the variance in functional connectivity between the DMN nodes was attributed to genetic contribution with the greatest heritability found for functional connectivity between the posterior cingulate and right inferior parietal nodes (P<0.001). Our data provide new evidence that functional connectivity measures from the intrinsic DMN derived from task-based fMRI datasets are under genetic control and have the potential to serve as endophenotypes for genetically predisposed psychiatric and neurological disorders. PMID:24453120

Korgaonkar, Mayuresh S; Ram, Kaushik; Williams, Leanne M; Gatt, Justine M; Grieve, Stuart M

2014-08-01

174

Comparing irradiance fields derived from Moderate Resolution Imaging Spectroradiometer airborne simulator cirrus cloud retrievals with solar spectral flux radiometer measurements  

NASA Astrophysics Data System (ADS)

During the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment, the Moderate Resolution Imaging Spectroradiometer (MODIS) airborne simulator (MAS) and the solar spectral flux radiometer (SSFR) operated on the same aircraft, the NASA ER-2. While MAS provided two-dimensional horizontal fields of cloud optical thickness and effective ice particle radius, the SSFR measured spectral irradiance in the visible to near-infrared wavelength range (0.3-1.7 ?m). The MAS retrievals, along with vertical profiles from a combined radar/lidar system on board the same aircraft were used to construct three-dimensional cloud fields, which were input into Monte Carlo radiative transfer models. The simulated field of spectral albedo (ratio of reflected upwelling to incident downwelling irradiance) was compared with the SSFR measurements. For two cases, the relative importance of spatial cloud heterogeneities, various approximations of the single scattering parameters, vertical structure, cirrus optical thickness, and ice crystal effective radius was studied.

Schmidt, K. Sebastian; Pilewskie, Peter; Platnick, Steven; Wind, Gala; Yang, Ping; Wendisch, Manfred

2007-12-01

175

Differential input preamplifier  

NASA Technical Reports Server (NTRS)

Preamplifier chops and amplifies very low level output of thermopile infrared detectors that will be used to measure thermal energy flux of Jupiter and its departure from a blackbody spectrum. Output signal has negligible phase shift. AC signal is RC-coupled to input stage of other amplifiers.

Callaway, P. W.

1972-01-01

176

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

177

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

NASA Astrophysics Data System (ADS)

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

Schneider, Nicholas M.; IUVS Science Team

2013-10-01

178

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

NASA Astrophysics Data System (ADS)

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

Lamichhane, Narottam

179

Sensible Heat Flux Derived From A Satellite Images and A Large Aperture Scintillometer. Results From The Gediz-experimen  

NASA Astrophysics Data System (ADS)

In the summer of 1998 a field experiment was carried out in the Gediz river basin near Menemen, Turkey. The main objective of this experiment, initiated by joint IWMI (International Water Management Institute)/GDRS (General Directorate of Rural Ser- vices, Government of Turkey) was to estimate the evaporation (E) using several dif- ferent methods, to compare the results and to assess the utility of each method for different applications. The Meteorology and Air Quality Group of the Wageningen University installed a large aperture scintillometers (LAS) in order to provide 'ground- truth' measurements of the sensible heat flux (H). It is the objective of this paper to present comparisons for H derived from satellites images and the LAS. Estimates of evaporation will be shown also.

Meijninger, W. M. L.; Gieske, A.; Bastiaanssen, W.; de Bruin, H. A. R.

180

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

181

Two-photon fluorescent probe derived from naphthalimide for cysteine detection and imaging in living cells.  

PubMed

A maleimide coupling naphthalimide was reported as new two-photon fluorescent (TPF) probe for cysteine (Cys). The probe was weakly fluorescent itself due to the donor-excited photoinduced electron transfer (d-PET). After reaction with Cys, d-PET process was blocked and fluorescence enhancement of the probe was observed at 470nm. The d-PET principle was rationalized by theoretical calculations with density functional theory and time-dependent density functional theory. Thiol-maleimide addition between the probe and Cys was confirmed by (1)H NMR and mass spectrum measurements. TPF analysis demonstrated a 24.7-fold emission increase of the probe induced by Cys upon excitation at 760nm. The two-photon action cross-section of probe-Cys adduct at 760nm reached 42GM compared to 1.7GM for free probe. The probe showed high sensitivity and selectivity to Cys over other potential interferences; especially it had the capability to discriminate Cys from glutathione and homocysteine. Through TPF imaging, the probe was successfully applied in the detection of Cys in living cells. PMID:25240143

Liu, Yanbin; Liu, Yuwen; Liu, Wei; Liang, Shucai

2015-02-25

182

Two-photon fluorescent probe derived from naphthalimide for cysteine detection and imaging in living cells  

NASA Astrophysics Data System (ADS)

A maleimide coupling naphthalimide was reported as new two-photon fluorescent (TPF) probe for cysteine (Cys). The probe was weakly fluorescent itself due to the donor-excited photoinduced electron transfer (d-PET). After reaction with Cys, d-PET process was blocked and fluorescence enhancement of the probe was observed at 470 nm. The d-PET principle was rationalized by theoretical calculations with density functional theory and time-dependent density functional theory. Thiol-maleimide addition between the probe and Cys was confirmed by 1H NMR and mass spectrum measurements. TPF analysis demonstrated a 24.7-fold emission increase of the probe induced by Cys upon excitation at 760 nm. The two-photon action cross-section of probe-Cys adduct at 760 nm reached 42 GM compared to 1.7 GM for free probe. The probe showed high sensitivity and selectivity to Cys over other potential interferences; especially it had the capability to discriminate Cys from glutathione and homocysteine. Through TPF imaging, the probe was successfully applied in the detection of Cys in living cells.

Liu, Yanbin; Liu, Yuwen; Liu, Wei; Liang, Shucai

2015-02-01

183

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

184

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

PubMed

Mesenchymal stem cells (MSCs) contribute to the recovery of tissue injury, providing a paracrine support. Cell-derived extracellular vesicles (EVs), carrying membrane and cytoplasmatic constituents of the cell of origin, have been described as a fundamental mechanism of intercellular communication. We previously demonstrated that EVs derived from human MSCs accelerated recovery following acute kidney injury (AKI) in vivo. The aim of the present study was to investigate the biodistribution and the renal localization of EVs in AKI. For this purpose, two methods for EV labeling suitable for in vivo tracking with optical imaging (OI), were employed using near infrared (NIR) dye (DiD): i) labeled EVs were generated by MSCs pre-incubated with NIR dye and collected from cell supernatants; ii) purified EVs were directly labeled with NIR dye. EVs obtained with these two procedures were injected intravenously (i.v.) into mice with glycerol-induced AKI and into healthy mice to compare the efficacy of the two labeling methods for in vivo detection of EVs at the site of damage. We found that the labeled EVs accumulated specifically in the kidneys of the mice with AKI compared with the healthy controls. After 5 h, the EVs were detectable in whole body images and in dissected kidneys by OI with both types of labeling procedures. The directly labeled EVs showed a higher and brighter fluorescence compared with the labeled EVs produced by cells. The signal generated by the directly labeled EVs was maintained in time, but provided a higher background than that of the labeled EVs produced by cells. The comparison of the two methods indicated that the latter displayed a greater specificity for the injured kidney. PMID:24573178

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

2014-05-01

185

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

PubMed Central

Mesenchymal stem cells (MSCs) contribute to the recovery of tissue injury, providing a paracrine support. Cell-derived extracellular vesicles (EVs), carrying membrane and cytoplasmatic constituents of the cell of origin, have been described as a fundamental mechanism of intercellular communication. We previously demonstrated that EVs derived from human MSCs accelerated recovery following acute kidney injury (AKI) in vivo. The aim of the present study was to investigate the biodistribution and the renal localization of EVs in AKI. For this purpose, two methods for EV labeling suitable for in vivo tracking with optical imaging (OI), were employed using near infrared (NIR) dye (DiD): i) labeled EVs were generated by MSCs pre-incubated with NIR dye and collected from cell supernatants; ii) purified EVs were directly labeled with NIR dye. EVs obtained with these two procedures were injected intravenously (i.v.) into mice with glycerol-induced AKI and into healthy mice to compare the efficacy of the two labeling methods for in vivo detection of EVs at the site of damage. We found that the labeled EVs accumulated specifically in the kidneys of the mice with AKI compared with the healthy controls. After 5 h, the EVs were detectable in whole body images and in dissected kidneys by OI with both types of labeling procedures. The directly labeled EVs showed a higher and brighter fluorescence compared with the labeled EVs produced by cells. The signal generated by the directly labeled EVs was maintained in time, but provided a higher background than that of the labeled EVs produced by cells. The comparison of the two methods indicated that the latter displayed a greater specificity for the injured kidney. PMID:24573178

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

2014-01-01

186

Photometric parameter maps of the Moon derived from LROC WAC images  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

187

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

NASA Technical Reports Server (NTRS)

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

Richardson, Laurie L.; Ambrosia, Vincent G.

1996-01-01

188

Derivation of lowland riparian wetland deposit architecture using geophysical image analysis and interface detection  

NASA Astrophysics Data System (ADS)

groundwater-surface water interactions to be understood in complex wetland settings, the architecture of the underlying deposits requires investigation at a spatial resolution sufficient to characterize significant hydraulic pathways. Discrete intrusive sampling using conventional approaches provides insufficient sample density and can be difficult to deploy on soft ground. Here a noninvasive geophysical imaging approach combining three-dimensional electrical resistivity tomography (ERT) and the novel application of gradient and isosurface-based edge detectors is considered as a means of illuminating wetland deposit architecture. The performance of three edge detectors were compared and evaluated against ground truth data, using a lowland riparian wetland demonstration site. Isosurface-based methods correlated well with intrusive data and were useful for defining the geometries of key geological interfaces (i.e., peat/gravels and gravels/Chalk). The use of gradient detectors approach was unsuccessful, indicating that the assumption that the steepest resistivity gradient coincides with the associated geological interface can be incorrect. These findings are relevant to the application of this approach in settings with a broadly layered geology with strata of contrasting resistivities. In addition, ERT revealed substantial structures in the gravels related to the depositional environment (i.e., braided fluvial system) and a complex distribution of low-permeability putty Chalk at the bedrock surface—with implications for preferential flow and variable exchange between river and groundwater systems. These results demonstrate that a combined approach using ERT and edge detectors can provide valuable information to support targeted monitoring and inform hydrological modeling of wetlands.

Chambers, J. E.; Wilkinson, P. B.; Uhlemann, S.; Sorensen, J. P. R.; Roberts, C.; Newell, A. J.; Ward, W. O. C.; Binley, A.; Williams, P. J.; Gooddy, D. C.; Old, G.; Bai, L.

2014-07-01

189

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

PubMed Central

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

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

2014-01-01

190

PET image reconstruction with a system matrix containing point spread function derived from single photon incidence response  

NASA Astrophysics Data System (ADS)

A point spread function (PSF) for the blurring component in positron emission tomography (PET) is studied. The PSF matrix is derived from the single photon incidence response function. A statistical iterative reconstruction (IR) method based on the system matrix containing the PSF is developed. More specifically, the gamma photon incidence upon a crystal array is simulated by Monte Carlo (MC) simulation, and then the single photon incidence response functions are calculated. Subsequently, the single photon incidence response functions are used to compute the coincidence blurring factor according to the physical process of PET coincidence detection. Through weighting the ordinary system matrix response by the coincidence blurring factors, the IR system matrix containing the PSF is finally established. By using this system matrix, the image is reconstructed by an ordered subset expectation maximization (OSEM) algorithm. The experimental results show that the proposed system matrix can substantially improve the image radial resolution, contrast, and noise property. Furthermore, the simulated single gamma-ray incidence response function depends only on the crystal configuration, so the method could be extended to any PET scanner with the same detector crystal configuration. Project supported by the National Natural Science Foundation of China (Grant Nos. Y4811H805C and 81101175).

Fan, Xin; Wang, Hai-Peng; Yun, Ming-Kai; Sun, Xiao-Li; Cao, Xue-Xiang; Liu, Shuang-Quan; Chai, Pei; Li, Dao-Wu; Liu, Bao-Dong; Wang, Lu; Wei, Long

2015-01-01

191

Near-infrared dye-conjugated amphiphilic hyaluronic Acid derivatives as a dual contrast agent for in vivo optical and photoacoustic tumor imaging.  

PubMed

Amphiphilic hyaluronic acid (HA) derivatives bearing hydrophobic indocyanine green dye derivatives and hydrophilic poly(ethylene glycol) were synthesized through the use of condensation and copper-catalyzed click cyclization reactions. The amphiphilic HA derivatives dissolved in water and formed self-assemblies in which the near-infrared dyes were tightly packed and arranged to form dimers or H-aggregates. By irradiating an aqueous solution of HA derivatives with near-infrared light, photoacoustic signals were detected along with fluorescence emission. Self-assemblies consisting of HA derivatives could smoothly accumulate in tumor tissues by passive tumor targeting. By utilizing HA derivatives as a contrast agent, tumor sites were clearly visualized by optical imaging as well as by photoacoustic tomography. PMID:25402751

Miki, Koji; Inoue, Tatsuhiro; Kobayashi, Yasuhito; Nakano, Katsuya; Matsuoka, Hideki; Yamauchi, Fumio; Yano, Tetsuya; Ohe, Kouichi

2015-01-12

192

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

193

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

SciTech Connect

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

Smallwood, David Ora

2005-09-01

194

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

195

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

NASA Astrophysics Data System (ADS)

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

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

2006-10-01

196

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

197

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

198

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

199

Validation of plasmasphere electron density reconstructions derived from data on board CHAMP by IMAGE/RPI data  

NASA Astrophysics Data System (ADS)

Plasmaspheric electron content is, beyond the ionosphere as major source, a significant contributor to the overall TEC budget affecting GNSS signals. The plasmasphere can induce half or more of the GNSS range errors caused by atmospheric electrical charges, in particular at nighttime. At DLR Neustrelitz, Germany, GPS measurements recorded onboard the LEO satellite CHAMP were used to reconstruct the topside electron density distribution (ionosphere and plasmasphere) up to GPS altitude, applying a model-based assimilation technique. In this paper, the potential of these CHAMP topside reconstructions for analyzing space weather related changes in the geo-plasma is investigated. For this purpose, comparisons are made between the CHAMP reconstructed profiles and electron densities derived from passive radio wave observations by the IMAGE RPI instrument for years 2001 till 2005. The comparison results indicate that an improvement, compared to the electron density of a background model, can be achieved by CHAMP data assimilation. The improvement is especially visible in the L-shell region below 3, which contributes notably to the GNSS signal delays. However, for the region around the plasmapause, systematical electron density underestimations of the background model w.r.t. the IMAGE data are detected. The rather limited CHAMP data coverage and the degraded observation geometry at these high altitudes seem to be not sufficient for complete compensation of this underestimation during the assimilation procedure. The results presented in this paper demonstrate the strengths of LEO TEC data assimilation, but at the same time illustrate the necessity to improve the modeling of the plasmasphere region above 4 ER L-shell distances. Furthermore, they reveal the need of additional data to establish an appropriate data base for the modeling of the complete plasmasphere.

Gerzen, T.; Feltens, J.; Jakowski, N.; Galkin, I.; Denton, R.; Reinisch, B.; Zandbergen, R.

2015-01-01

200

Nitroxide derivatives for imaging of hypercholesterolemia-induced kidney dysfunction and assessing the effectiveness of antilipidemic drugs.  

PubMed

The present study was designed to clarify the possibility for application of nitroxide derivatives in magnetic resonance imaging (MRI) of hypercholesterolemia-mediated renal dysfunction in mice, as well as to assess the effectiveness of antilipidemic drugs (cholestyramine and ezetimibe). The mice were separated in four groups: (i) on a normal diet (ND) without medication (control); (ii) on a high cholesterol diet (CD) without medication; (iii) CD mice receiving cholestyramine; and (iv) CD mice receiving ezetimibe. In CD mice without medication, a hypercholesterolemia was developed, detected by the increasing of total plasma cholesterol and non-HDL cholesterol, and decreasing of HDL cholesterol. The hypercholesterolemia compromised renal function: blood urea nitrogen, creatine and uric acid increased significantly, accompanied with development of glomerulosclerosis, enhancement of the amount of neutrophils and overexpression of metalloproteinase-9. The mice were subjected to anesthesia and MR imaging was performed on 7 T magnet (T1-weighted incoherent gradient-echo sequence; fast low-angle shot). The region-of-interest was selected within the kidney. The images were obtained before and after injection of contrast probe [carbamoyl-PROXYL (CMP) or Gd-DTPA]. In the kidney of ND mice, the MRI signal intensity increased after injection of CMP, reached a maximum (very well-defined renal filtration peak) and decreased to the baseline level within 14 min. In kidney of CD mice, the CMP-mediated enhancement of MRI signal was not detected. Antilipidemic drugs patially abolished the effect of hypercholesterolemia on CMP-enhanced MRI in the kidney. The kinetic curves of Gd-enhanced MRI signal had also different profiles in the kidney of ND and CD mice. They were similar to the profiles of the kinetic curves, obtained from MR urography of healthy human and human with renal pathology, respectively. The present study suggests that CMP is a suitable MRI contrast probe for visualization of hypercholesterolemia-induced renal dysfunction in intact animals and the assessment of the efficacy of antilipidemic drugs. The probe was applied at a concentration that was 3 times lower than the LD50 for intravenous administration in mice. Since the probe is excreted by the kidney, it could be considered harmless for mammalians in the selected dose and appropriate candidate for translational research. PMID:21744874

Tomizawa, Atsuyuki; Hadjidekov, George; Ishii, Itsuko; Bakalova, Rumiana; Zhelev, Zhivko; Aoki, Ichio; Saga, Tsuneo; Kitada, Mitsukazu

2011-10-01

201

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

ERIC Educational Resources Information Center

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

Serhan, Derar

2009-01-01

202

In vivo imaging of adipose-derived mesenchymal stem cells in female nude mice after simulated childbirth injury  

PubMed Central

The aim of the present study was to track in vivo the distribution and survival of adipose-derived mesenchymal stem cells (ASCs) transplanted into female BALB/c nude mice following simulated childbirth injury, using green fluorescent protein and luciferase dual labeling, bioluminescent imaging (BLI) and histological evaluation. The results demonstrated that the dually labeled ASCs could be detected for up to eight weeks in vivo. The number of implanted cells decreased during the first three weeks, and then stabilized until the end of the experiment. According to the linear regression plot, ~27,621 implanted cells survived until eight weeks after implantation. Transplanted ASCs predominantly existed at the inoculation site of the vagina, with little or no spread to other organs. Histological analysis confirmed the survival of the engrafted ASCs. The study provided basic evidence that BLI techniques can be used to monitor ASCs in vivo in real time and in the long term. Through local administration, ASCs could survive in the long term to facilitate repair following pelvic-floor injury. PMID:25574200

DAI, MIAO; XU, PEIRONG; HOU, MIN; TENG, YINCHENG; WU, QINGKAI

2015-01-01

203

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

PubMed Central

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

2013-01-01

204

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

205

Modeling and generating input processes  

SciTech Connect

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

Johnson, M.E.

1987-01-01

206

Impulsive Inputs for Feedback Control and Hybrid System  

E-print Network

1 Impulsive Inputs for Feedback Control and Hybrid System Modeling Alexander B description of feedback control theory in the class of impulsive inputs which allow higher derivatives form. Further described are physically realizable approximations of the "ideal" impulse-type solutions

Varaiya, Pravin

207

Color image restoration based on camera microscanning  

NASA Astrophysics Data System (ADS)

In this work, we propose a method to restore color images from a set of degraded color images obtained with a microscanning imaging system. Using the set of observed images, image restoration is carried out by solving a system of equations that is derived from optimization of an objective function. Since the proposed method possesses a high computational complexity, a fast algorithm is developed. Experimental and computer simulation results obtained with the proposed method are analyzed in terms of restoration accuracy and tolerance to additive input noise.

López Martínez, José L.; Kober, Vitaly; Escalante-Torres, Manuel

2014-09-01

208

Modeling Recognition Memory Using the Similarity Structure of Natural Input  

ERIC Educational Resources Information Center

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

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

2006-01-01

209

A Kalman Filter Based Tracking Scheme with Input Estimation  

Microsoft Academic Search

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

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

1979-01-01

210

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. PMID:22291826

Wili?ski, Jerzy; Czarnecka, Danuta; Wojciechowska, Wiktoria; Kloch-Bade?ek, Ma?gorzata; Jastrz?bski, Marek; Bacior, Bogumi?a; Sondej, Tomasz; Kusiak, Aleksander

2011-01-01

211

SDR Input Power Estimation Algorithms  

NASA Technical Reports Server (NTRS)

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

Nappier, Jennifer M.; Briones, Janette C.

2013-01-01

212

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

213

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

214

Learning to represent visual input  

PubMed Central

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

Hinton, Geoffrey E.

2010-01-01

215

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

216

Derivation of a MODIS-compatible enhanced vegetation index from visible infrared imaging radiometer suite spectral reflectances using vegetation isoline equations  

NASA Astrophysics Data System (ADS)

We developed a unique methodology that spectrally translates the enhanced vegetation index (EVI) across sensors for data continuity based on vegetation isoline equations and derived a moderate resolution imaging spectroradiometer (MODIS)-compatible EVI for the visible/infrared imager/radiometer suite (VIIRS) sensor. The derived equation had four coefficients that were a function of soil, canopy, and atmosphere, e.g., soil line slope, leaf area index (LAI), and aerosol optical thickness (AOT). The PROSAIL canopy reflectance and 6S atmospheric models were employed to numerically characterize the MODIS-compatible VIIRS EVI. MODIS-compatible VIIRS EVI values only differed from those of MODIS EVI by, at most, 0.002 EVI units, whereas VIIRS and MODIS EVI values differed by 0.018 EVI units. The derived coefficients were sensitive mainly to LAI and AOT for the full- and a partial-covered canopy, respectively. The MODIS-compatible EVI resulted in a reasonable level of accuracy when the coefficients were fixed at values found via optimization for model-simulated and actual sensor data (83 and 41% reduction in the root mean square error, respectively), demonstrating the potential practical utility of the derived equation. The developed methodology can be used to obtain a spectrally compatible EVI for any pair of sensors in the data continuity context.

Obata, Kenta; Miura, Tomoaki; Yoshioka, Hiroki; Huete, Alfredo R.

2013-01-01

217

Statistical linearization for multi-input/multi-output nonlinearities  

NASA Technical Reports Server (NTRS)

Formulas are derived for the computation of the random input-describing functions for MIMO nonlinearities; these straightforward and rigorous derivations are based on the optimal mean square linear approximation. The computations involve evaluations of multiple integrals. It is shown that, for certain classes of nonlinearities, multiple-integral evaluations are obviated and the computations are significantly simplified.

Lin, Ching-An; Cheng, Victor H. L.

1991-01-01

218

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

PubMed

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

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

2014-06-01

219

REL - English Bulk Data Input.  

ERIC Educational Resources Information Center

A bulk data input processor which is available for the Rapidly Extensible Language (REL) English versions is described. In REL English versions, statements that declare names of data items and their interrelationships normally are lines from a terminal or cards in a batch input stream. These statements provide a convenient means of declaring some…

Bigelow, Richard Henry

220

Input a journal Viewing Journals  

E-print Network

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

Sussex, University of

221

Optical-Input, Optical-Output Morphological Processor  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

222

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

223

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

PubMed Central

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

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

2014-01-01

224

Synthesis and evaluation of 18F-fluoroethylated benzothiazole derivatives for in vivo imaging of amyloid plaques in Alzheimer's disease  

Microsoft Academic Search

Amyloid aggregates play a major role in the development of Alzheimer's disease. Targeting these aggregates by PET probes enables non-invasively the detection and quantification of amyloid deposit distribution in human brains. Based on benzothiazole core structure a series of amyloid imaging agents were developed. Currently [11C]2-(4?-(methylamino)phenyl)-6-hydroxybenzothiazole (Pittsburgh Compound-B (PIB) is the most specific and widely used amyloid imaging ligand. But

B. Neumaier; S. Deisenhofer; C. Sommer; C. Solbach; S. N. Reske; F. Mottaghy

2010-01-01

225

Image Calibration  

NASA Technical Reports Server (NTRS)

Calibrate_Image calibrates images obtained from focal plane arrays so that the output image more accurately represents the observed scene. The function takes as input a degraded image along with a flat field image and a dark frame image produced by the focal plane array and outputs a corrected image. The three most prominent sources of image degradation are corrected for: dark current accumulation, gain non-uniformity across the focal plane array, and hot and/or dead pixels in the array. In the corrected output image the dark current is subtracted, the gain variation is equalized, and values for hot and dead pixels are estimated, using bicubic interpolation techniques.

Peay, Christopher S.; Palacios, David M.

2011-01-01

226

Synthesis of superparamagnetic iron oxide nanoparticles coated with a DDNP-carboxyl derivative for in vitro magnetic resonance imaging of Alzheimer's disease.  

PubMed

Superparamagnetic iron oxide nanoparticles (SPIONs) have been proposed for use in magnetic resonance imaging as versatile ultra-sensitive nanoprobes for Alzheimer's disease imaging. In this work, we synthetized an efficient contrast agent of Alzheimer's disease using 1,1-dicyano-2-[6-(dimethylamino)naphthalene-2-yl]propene (DDNP) carboxyl derivative to functionalize the surface of SPIONs. The DDNP-SPIONs are prepared by conjugating DDNP carboxyl derivative to oleic acid-treated SPIONs through ligand exchange. The structure, size distribution and magnetic property were identified by IR, TGA-DTA, XRD, TEM, Zetasizer Nano and VSM. TEM and Zetasizer Nano observations indicated that the DDNP-SPIONs are relatively mono-dispersed spherical distribution with an average size of 11.7nm. The DDNP-SPIONs were then further analyzed for their MRI relaxation properties using MR imaging and demonstrated high T2 relaxivity of 140.57s(-1)FemM(-1), and the vitro experiment that DDNP-SPIONs binding to ?-Amyloid aggregates were then investigated by fluorophotometry, the results showed that the combination had induced the fluorescence enhancement of the DDNP-SPIONs and displayed tremendous promise for use as a contrast agent of Alzheimer's disease in MRI. PMID:24582259

Zhou, Jingting; Fa, Huanbao; Yin, Wei; Zhang, Jin; Hou, Changjun; Huo, Danqun; Zhang, Dong; Zhang, Haifeng

2014-04-01

227

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

Microsoft Academic Search

A new source of vector wind stress data is assessed relative to existing analyses of the surface wind field. The large-scale variability of vector wind stress generated by Atlas et al. (1991) and based on the special sensor microwave imager (SSM\\/I) remotely sensed observations of surface wind speed is compared with five operational and subjectively analyzed wind products across the

Antonio J. Busalacchi; Robert M. Atlas; Eric C. Hackert

1993-01-01

228

Aberrations of holographic lenses in image quality evaluation  

Microsoft Academic Search

The imaging quality of holographic lenses depends on parameters that include the shape of a holographic lens surface or an input pupil position. Based on the formulas for third-order aberration coefficients derived for such cases, conditions that ensure the correction of aperture and field aberrations are given. The possibility of joint correction of spherical aberration, coma, and astigmatism is discussed.

Boguslawa Dubik; Jan Masajada; Jerzy Nowak; Marek Zajac

1992-01-01

229

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

230

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

231

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

PubMed Central

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

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

2013-01-01

232

Comparison of Texture Features Derived from Static and Respiratory-Gated PET Images in Non-Small Cell Lung Cancer  

PubMed Central

Background PET-based texture features have been used to quantify tumor heterogeneity due to their predictive power in treatment outcome. We investigated the sensitivity of texture features to tumor motion by comparing static (3D) and respiratory-gated (4D) PET imaging. Methods Twenty-six patients (34 lesions) received 3D and 4D [18F]FDG-PET scans before the chemo-radiotherapy. The acquired 4D data were retrospectively binned into five breathing phases to create the 4D image sequence. Texture features, including Maximal correlation coefficient (MCC), Long run low gray (LRLG), Coarseness, Contrast, and Busyness, were computed within the physician-defined tumor volume. The relative difference (?3D-4D) in each texture between the 3D- and 4D-PET imaging was calculated. Coefficient of variation (CV) was used to determine the variability in the textures between all 4D-PET phases. Correlations between tumor volume, motion amplitude, and ?3D-4D were also assessed. Results 4D-PET increased LRLG (?=?1%–2%, p<0.02), Busyness (?=?7%–19%, p<0.01), and decreased MCC (?=?1%–2%, p<7.5×10?3), Coarseness (?=?5%–10%, p<0.05) and Contrast (?=?4%–6%, p>0.08) compared to 3D-PET. Nearly negligible variability was found between the 4D phase bins with CV<5% for MCC, LRLG, and Coarseness. For Contrast and Busyness, moderate variability was found with CV?=?9% and 10%, respectively. No strong correlation was found between the tumor volume and ?3D-4D for the texture features. Motion amplitude had moderate impact on ? for MCC and Busyness and no impact for LRLG, Coarseness, and Contrast. Conclusions Significant differences were found in MCC, LRLG, Coarseness, and Busyness between 3D and 4D PET imaging. The variability between phase bins for MCC, LRLG, and Coarseness was negligible, suggesting that similar quantification can be obtained from all phases. Texture features, blurred out by respiratory motion during 3D-PET acquisition, can be better resolved by 4D-PET imaging. 4D-PET textures may have better prognostic value as they are less susceptible to tumor motion. PMID:25517987

Yip, Stephen; McCall, Keisha; Aristophanous, Michalis; Chen, Aileen B.

2014-01-01

233

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

234

Image-Guided PO2 Probe Measurements Correlated with Parametric Images Derived from 18F-Fluoromisonidazole Small-Animal PET Data in Rats  

PubMed Central

18F-fluoromisonidazole PET, a noninvasive means of identifying hypoxia in tumors, has been widely applied but with mixed results, raising concerns about its accuracy. The objective of this study was to determine whether kinetic analysis of dynamic 18F-fluoromisonidazole data provides better discrimination of tumor hypoxia than methods based on a simple tissue-to-plasma ratio. Methods Eleven Dunning R3327-AT prostate tumor-bearing nude rats were immobilized in custom-fabricated whole-body molds, injected intravenously with 18F-fluoromisonidazole, and imaged dynamically for 105 min. They were then transferred to a robotic system for image-guided measurement of intratumoral partial pressure of oxygen (PO2). The dynamic 18F-fluoromisonidazole uptake data were fitted with 2 variants of a 2-compartment, 3-rate-constant model, one constrained to have K1 equal to k2 and the other unconstrained. Parametric images of the rate constants were generated. The PO2 measurements were compared with spatially registered maps of kinetic rate constants and tumor-to-plasma ratios. Results The constrained pharmacokinetic model variant was shown to provide fits similar to that of the unconstrained model and did not introduce significant bias in the results. The trapping rate constant, k3, of the constrained model provided a better discrimination of low PO2 than the tissue-to-plasma ratio or the k3 of the unconstrained model. Conclusion The use of kinetic modeling on a voxelwise basis can identify tumor hypoxia with improved accuracy over simple tumor-to-plasma ratios. An effective means of controlling noise in the trapping rate constant, k3, without introducing significant bias, is to constrain K1 equal to k2 during the fitting process. PMID:22933821

Bartlett, Rachel M.; Beattie, Bradley J.; Naryanan, Manoj; Georgi, Jens-Christoph; Chen, Qing; Carlin, Sean D.; Roble, Gordon; Zanzonico, Pat B.; Gonen, Mithat; O’Donoghue, Joseph; Fischer, Alexander; Humm, John L.

2013-01-01

235

(constrain 4bar ((basea input)  

E-print Network

2 gamma3 psi2 psi3) ((Complex? D2) (Complex? D3) (number? phi2) (number? phi3) (number? gamma2) (number? gamma3) (number? psi2) (number? psi3)) (let ((Cphi2 (new Complex (real (cos phi2)) (imag (sin phi (new Complex (real (cos psi2)) (imag (sin psi2)))) (Cpsi3 (new Complex (real (cos psi3)) (imag (sin psi

Salustri, Filippo A.

236

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

PubMed Central

Background Histological behavior of glioblastoma multiforme suggests it would benefit more from a global rather than regional evaluation. A global (whole-brain) calculation of diffusion tensor imaging (DTI) derived tensor metrics offers a valid method to detect the integrity of white matter structures without missing infiltrated brain areas not seen in conventional sequences. In this study we calculated a predictive model of brain infiltration in patients with glioblastoma using global tensor metrics. Methods Retrospective, case and control study; 11 global DTI-derived tensor metrics were calculated in 27 patients with glioblastoma multiforme and 34 controls: mean diffusivity, fractional anisotropy, pure isotropic diffusion, pure anisotropic diffusion, the total magnitude of the diffusion tensor, linear tensor, planar tensor, spherical tensor, relative anisotropy, axial diffusivity and radial diffusivity. The multivariate discriminant analysis of these variables (including age) with a diagnostic test evaluation was performed. Results The simultaneous analysis of 732 measures from 12 continuous variables in 61 subjects revealed one discriminant model that significantly differentiated normal brains and brains with glioblastoma: Wilks’ ? = 0.324, ?2 (3) = 38.907, p < .001. The overall predictive accuracy was 92.7%. Conclusions We present a phase II study introducing a novel global approach using DTI-derived biomarkers of brain impairment. The final predictive model selected only three metrics: axial diffusivity, spherical tensor and linear tensor. These metrics might be clinically applied for diagnosis, follow-up, and the study of other neurological diseases. PMID:24991202

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

2014-01-01

237

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

PubMed

Perfusion-weighted imaging (PWI) measures can predict tissue outcome in acute ischemic stroke. Accuracy might be improved if differential tissue susceptibility to ischemia is considered. We present a novel voxel-by-voxel analysis to characterize cerebral blood flow (CBF) separately in gray (GM) and white matter (WM). Ten patients were scanned with inversion-recovery spin-echo EPI (IRSEPI), diffusion-weighted imaging (DWI), PWI<6 h from onset and fluid attenuated inversion-recovery (FLAIR) at 30 days. Image processing included coregistration to PWI, automatic segmentation of IRSEPI into GM, WM and CSF and semiautomatic segmentation of DWI/FLAIR to derive the acute and 30-day lesions. Five tissue compartments were defined: (1) 'Core' (abnormal acutely and at 30 days), (2) 'Growth' (or 'infarcted penumbra', abnormal only at 30 days), (3) 'Reversed' (abnormal acutely but normal at 30 days), (4) 'MTT-Delayed ' (tissue with delayed mean transit time but not part of the acute or 30-day lesion), and (5) 'Normal' brain. Cerebral blood flow in GM and WM of each compartment was obtained from quantitative maps. Gray matter and WM mean CBF in the growth region differed by 5.5 mL/100 g min (P=0.015). Mean CBF also differed significantly within normal and MTT-Delayed compartments. The difference in the reversed region approached statistical significance. In core, GM and WM CBF did not differ. The results suggest separate ischemic thresholds for GM and WM in stroke penumbra. PMID:15889045

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

2005-09-01

238

Evaluation of the Iron(iii) Complex of the 3,5 - Derivative of Catechol as AN Organ-Selective Magnetic Resonance Imaging Contrast Agent.  

NASA Astrophysics Data System (ADS)

The iron (III) diethylsulfonamide derivative of catechol (Fe(III)-DESAC) is a new target selective magnetic resonance imaging contrast agent based on the second-sphere interaction mechanism. It is a highly stable tris-complex that was chemically characterized for potential use as a magnetopharmaceutical. The contrast agent was evaluated for gross toxicity and biodistribution in a Fisher 344 rat model. The agent showed no significant acute toxicity at low doses. At a higher dose, 0.15 mmol/kg, the contrast agent exhibited toxic effects in test animals. No signs of abnormal behavior or chronic toxicity was noted. Biodistribution studies revealed increased uptake by the liver parenchyma and the kidneys suggesting combined hepatobiliary and renal excretion. Its potential as a magnetopharmaceutical was evaluated using a GE Signa MRI scanner at 0.1 mmol/kg doses in phantom and an animal model. Relaxivity measurements resulted in R_1 and R_2 relaxivity values of 2.47 mM^{ -1} sec^{-1} and 3.16 mM^{-1} sec ^{-1}, respectively. T _1-weighted MR images showed 63% increase in the liver image values and 99% increase in the kidney values. This contrast enhancement was approximately 75% greater in the healthy parenchyma compared to the imbedded mammary adenocarcinoma.

Sayed, M. Gary

239

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

PubMed Central

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

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

2013-01-01

240

Systems and methods for reconfiguring input devices  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

241

Signal Prediction With Input Identification  

NASA Technical Reports Server (NTRS)

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

Juang, Jer-Nan; Chen, Ya-Chin

1999-01-01

242

Analog Input Data Acquisition Software  

NASA Technical Reports Server (NTRS)

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

Arens, Ellen

2009-01-01

243

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

244

LAT1 Targeted Delivery of Methionine Based Imaging Probe Derived from M(III) Metal Ions for Early Diagnosis of Proliferating Tumors using Molecular Imaging Modalities.  

PubMed

We investigated the potential of DTPA-bis(Methionine), a target specific amino acid based probe for detection of L-type amino acid transporters (LAT1) over expressed in proliferating tumors using multimodality imaging. The ligand, DTPA-bis(Met) was readily converted to lanthanide complexes and were found capable of targeting cancer cells using multimodality imaging. DTPA-bis(Met) complexes were synthesized and characterized by mass spectroscopy. MR longitudinal relaxivity, r1=4.067 ± 0.31 mM-1s-1 and transverse relaxivity, r2= 8.61 ± 0.07 mM-1s-1 of Gd(III)-DTPA-bis(Met) was observed at pH 7.4 at 7T. Bright, localized fluorescence of Eu(III)-DTPA-bis(MET) was observed with standard microscopy and displacement studies indicated ligand functionality. KD value determined for Eu(III)-DTPA-bis(Met) on U-87MG cells was found to be 17.3 pM and showed appreciable fluorescence within the cells. Radio HPLC showed a radiochemical purity more than 95% (specific activity = 400-500 MBq/µmol, labeling efficiency 78 %) for 68Ga-DTPA-bis(Met). Pretreatment of xenografted U-87MG athymic mice with 68 Ga(III)-DTPA-bis(Met) following unlabeled L-methionine administration reduced tumor uptake by 10-folds in microPET. These data support the specific binding to LAT1 transporter of the 68 Ga(III)-DTPA-bis(Met). To summarize, this agent possesses high stability in biological environment, exhibits effective interaction with its LAT1 transporters giving high accumulation in tumor area, excellent tumor/non-tumor ratio and low non-specific retention in vivo. PMID:25329672

Hazari, Puja Panwar; Prakash, Surbhi; Meena, Virendra K; Jaswal, Ambika; Khurana, Harleen; Mishra, Surabhi Kirti; Kumar, B S Hemanth; Singh, Lokendra; Mishra, Anil K

2014-10-19

245

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

E-print Network

e e e e e e e e e ee ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡¡ N/2 Input Benes Network that the theorem is true for N=2 input Benes networks, i.e. we can establish node disjoint paths in an N=2 inputh ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡¡ h ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡¡ he e e e e e e e e e e e ee he e e e e e

Ranade, Abhiram G.

246

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

NASA Technical Reports Server (NTRS)

An assessment of a new source of vector wind stress data relative to existing analyses of the surface wind field is presented. The large-scale variability of vector wind stress generated by Atlas et al. (1991) and based on the special sensor microwave imager (SSM/I) remotely sensed observations of surface wind speed is compared with five operational and subjectively analyzed wind products across the tropical Pacific basin for the first year of SSM/I, July 1987 through June 1988. The spatial and temporal variability of the zonal component, meridional component, and curl of the wind stress are examined relative to their future use in wind-driven ocean model studies of tropical Pacific Ocean circulation.

Busalacchi, Antonio J.; Atlas, Robert M.; Hackhert, Eric C.

1993-01-01

247

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

248

A large area TDI image sensor for low light level imaging  

NASA Astrophysics Data System (ADS)

A 1030 x 128 element time delay and integration (TDI) CCD image sensor has been developed for low-light-level (LLL) imaging applications. For LLL imaging, output is derived from a high-gain low-noise floating-gate amplifier (FGA). For larger input signal levels, a second, resettable floating-gate amplifier (RFGA) with lower gain and wider dynamic range provides output in parallel to the FGA. The device features four-phase buried-channel construction and a polysilicon gate design tailored to produce optimum broad-band responsivity. Input signal levels of 500 electrons have been successfully imaged and amplifier noise levels of approximately 20 electrons have been observed.

Farrier, M. G.; Dyck, R. H.

1980-08-01

249

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

250

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

251

Retrospective analysis of outcomes after IVF using an aneuploidy risk model derived from time-lapse imaging without PGS.  

PubMed

Time-lapse imaging of human preimplantation IVF embryos has enabled objective algorithms based on novel observations of development (morphokinetics) to be used for clinical selection of embryos. Embryo aneuploidy, a major cause of IVF failure, has been correlated with specific morphokinetic variables used previously to develop an aneuploidy risk classification model. The purpose of this study was to evaluate the effectiveness and potential impact of this model for unselected IVF patients without biopsy and preimplantation genetic screening (PGS). Embryo outcomes - no implantation, fetal heart beat (FHB) and live birth (LB) - of 88 transferred blastocysts were compared according to calculated aneuploidy risk classes (low, medium, high). A significant difference was seen for FHB (P<0.0001) and LB (P<0.01) rates between embryos classified as low and medium risk. Within the low-risk class, relative increases of 74% and 56%, compared with rates for all blastocysts, were observed for FHB and LB respectively. The area under the receiver operating characteristic curve was 0.75 for FHB and 0.74 for LB. This study demonstrates the clinical relevance of the aneuploidy risk classification model and introduces a novel, non-invasive method of embryo selection to yield higher implantation and live birth rates without PGS. PMID:23683847

Campbell, Alison; Fishel, Simon; Bowman, Natalie; Duffy, Samantha; Sedler, Mark; Thornton, Simon

2013-08-01

252

National Hospital Input Price Index  

PubMed Central

The national community hospital input price index presented here isolates the effects of prices of goods and services required to produce hospital care and measures the average percent change in prices for a fixed market basket of hospital inputs. Using the methodology described in this article, weights for various expenditure categories were estimated and proxy price variables associated with each were selected. The index is calculated for the historical period 1970 through 1978 and forecast for 1979 through 1981. During the historical period, the input price index increased an average of 8.0 percent a year, compared with an average rate of increase of 6.6 percent for overall consumer prices. For the period 1979 through 1981, the average annual increase is forecast at between 8.5 and 9.0 percent. Using the index to deflate growth in expenses, the level of real growth in expenditures per inpatient day (net service intensity growth) averaged 4.5 percent per year with considerable annual variation related to government and hospital industry policies. PMID:10309052

Freeland, Mark S.; Anderson, Gerard; Schendler, Carol Ellen

1979-01-01

253

Digital image processing of vascular angiograms  

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

254

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

2011-05-14

255

Potential role of fractional anisotropy derived from diffusion tensor imaging in differentiating high-grade gliomas from low-grade gliomas: a meta-analysis  

PubMed Central

Background and purpose: It is crucial to accurately differentiate high-grade gliomas (HGGs) from low-grade gliomas (LGGs) preoperatively, as treatment strategies vary. So we performed a meta-analysis to assess the sensitivity and specificity of fractional anisotropy (FA) value derived from diffusion tensor imaging (DTI) in differentiating HGGs from LGGs. Materials and methods: Between January 2005 and June 2014, relevant articles were searched from the Embase and Medline databases for analysis. Statistical analyses were performed using Meta-Disc 1.4. Results: A total of 221 patients included in the FA analysis: 127 with HGGs and 94 LGGs. The pooled sensitivity, specificity and diagnostic odds ratio (DOR) for differentiating HGGs from LGGs were 93% (95% CI 0.87-0.97), 85% (95% CI 0.76-0.92), and 55.41 (95% CI 16.77-183.07), respectively. And computation of heterogeneity metrics revealed an acceptable level of the between-study heterogeneity of DOR (I2=30.9%). Conclusions: The results of our meta-analysis present that the FA derived from DTI act as a useful diagnostic marker could be used in distinguishing the HGGs from LGGs in the preoperative and the clinical application values are to be confirmed by further larger case-control studies. PMID:25419413

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

2014-01-01

256

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

257

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

PubMed

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

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

2013-12-01

258

Effects of control inputs on the estimation of stability and control parameters of a light airplane  

NASA Technical Reports Server (NTRS)

The maximum likelihood parameter estimation technique was used to determine the values of stability and control derivatives from flight test data for a low-wing, single-engine, light airplane. Several input forms were used during the tests to investigate the consistency of parameter estimates as it relates to inputs. These consistencies were compared by using the ensemble variance and estimated Cramer-Rao lower bound. In addition, the relationship between inputs and parameter correlations was investigated. Results from the stabilator inputs are inconclusive but the sequence of rudder input followed by aileron input or aileron followed by rudder gave more consistent estimates than did rudder or ailerons individually. Also, square-wave inputs appeared to provide slightly improved consistency in the parameter estimates when compared to sine-wave inputs.

Cannaday, R. L.; Suit, W. T.

1977-01-01

259

Synthesis, 68Ga-Radiolabeling, and Preliminary In Vivo Assessment of a Depsipeptide-Derived Compound as a Potential PET/CT Infection Imaging Agent  

PubMed Central

Noninvasive imaging is a powerful tool for early diagnosis and monitoring of various disease processes, such as infections. An alarming shortage of infection-selective radiopharmaceuticals exists for overcoming the diagnostic limitations with unspecific tracers such as 67/68Ga-citrate or 18F-FDG. We report here TBIA101, an antimicrobial peptide derivative that was conjugated to DOTA and radiolabeled with 68Ga for a subsequent in vitro assessment and in vivo infection imaging using Escherichia coli-bearing mice by targeting bacterial lipopolysaccharides with PET/CT. Following DOTA-conjugation, the compound was verified for its cytotoxic and bacterial binding behaviour and compound stability, followed by 68Gallium-radiolabeling. µPET/CT using 68Ga-DOTA-TBIA101 was employed to detect muscular E. coli-infection in BALB/c mice, as warranted by the in vitro results. 68Ga-DOTA-TBIA101-PET detected E. coli-infected muscle tissue (SUV = 1.3–2.4) > noninfected thighs (P = 0.322) > forearm muscles (P = 0.092) > background (P = 0.021) in the same animal. Normalization of the infected thigh muscle to reference tissue showed a ratio of 3.0 ± 0.8 and a ratio of 2.3 ± 0.6 compared to the identical healthy tissue. The majority of the activity was cleared by renal excretion. The latter findings warrant further preclinical imaging studies of greater depth, as the DOTA-conjugation did not compromise the TBIA101's capacity as targeting vector.

Mokaleng, Botshelo B.; Ebenhan, Thomas; Ramesh, Suhas; Govender, Thavendran; Kruger, Hendrik G.; Hazari, Puja P.; Mishra, Anil K.; Marjanovic-Painter, Biljana; Zeevaart, Jan R.; Sathekge, Mike M.

2015-01-01

260

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

261

Impact of remote sensing upon the planning, management and development of water resources. Summary of computers and computer growth trends for hydrologic modeling and the input of ERTS image data processing load  

NASA Technical Reports Server (NTRS)

An analysis of current computer usage by major water resources users was made to determine the trends of usage and costs for the principal hydrologic users/models. The laws and empirical relationships governing the growth of the data processing loads were described and applied to project the future data loads. Data loads for ERTS CCT image processing were computed and projected through the 1985 era. The analysis showns significant impact due to the utilization and processing of ERTS CCT's data.

Castruccio, P. A.; Loats, H. L., Jr.

1975-01-01

262

Convergence of multisensory inputs in the Xenopus tadpole tectum  

PubMed Central

The integration of multisensory information takes place in the optic tectum where visual and auditory/mechanosensory inputs converge and regulate motor outputs. The circuits which integrate multisensory information are poorly understood. In an effort to identify the basic components of a multisensory integrative circuit, we determined the projections of the mechanosensory input from the periphery to the optic tectum and compared their distribution to the retinotectal inputs in Xenopus laevis tadpoles using dye-labelling methods. The peripheral ganglia of the lateral line system project to the ipsilateral hindbrain and the axons representing mechanosensory inputs along the anterior/posterior body axis are mapped along the ventrodorsal axis in the axon tract in the dorsal column of the hindbrain. Hindbrain neurons project axons to the contralateral optic tectum. The neurons from anterior and posterior hindbrain regions project axons to the dorsal and ventral tectum, respectively. While the retinotectal axons project to a superficial lamina in the tectal neuropil, the hindbrain axons project to a deep neuropil layer. Calcium imaging showed that multimodal inputs converge on tectal neurons. The layer specific projections of the hindbrain and retinal axons suggest a functional segregation of sensory inputs to proximal and distal tectal cell dendrites, respectively. PMID:19813244

Hiramoto, Masateru; Cline, Hollis

2010-01-01

263

Images  

Cancer.gov

Images can be a powerful and direct means of communicating ideas and feelings about an organization and can create a personal connection with an audience. Imagery used for the main NCI website has been selected to give a consistent look throughout the site. Here are some recommended attributes for NCI website imagery.

264

Self-consistent input-output formulation of quantum feedback  

SciTech Connect

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

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

2010-12-15

265

Status of input design for aircraft parameter identification  

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

266

Guided image filtering.  

PubMed

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

He, Kaiming; Sun, Jian; Tang, Xiaoou

2013-06-01

267

The level and integrity of synaptic input regulates dendrite structure.  

PubMed

How localized synaptic input regulates dendritic branch structure is not well understood. For these experiments, we used single-cell electroporation, live cell imaging, in vitro deafferentation, pharmacology, and electrophysiological stimulation to study how local alterations in synaptic input affect dendritic branch structure in nucleus laminaris (NL). We found that interrupting or modulating synaptic input to distinct sets of NL dendrites can regulate their structure on a very short timescale. Specifically, eliminating synaptic input by deafferenting only one set of the bitufted NL dendrites caused a selective reduction in the total dendritic branch length of the deafferented dendrites but relatively few changes in the normally innervated dendrites on the same cell. An analysis of individual dendritic branch changes demonstrated that both control and deafferented NL dendrites exhibit branch extension and retraction. However, the presence of intact synaptic inputs balanced these changes, maintaining the total dendritic branch length of control dendrites. When glutamate receptor signaling was blocked (DNQX and AP-5), NL neurons exhibited significant dendrite retraction, demonstrating that NL dendrite maintenance depends in part on presynaptic glutamatergic input. Electrophysiological experiments further confirmed that modulating the level of synaptic input regulates NL dendrite structure. Differential stimulation of the two sets of dendrites resulted in a selective reduction in the total dendritic branch length of the unstimulated dendrites and a selective increase in the total dendritic branch length of the stimulated dorsal dendrites. These results suggest that balanced activation of the two sets of NL dendrites is required to maintain the relative amount of dendritic surface area allotted to each input. PMID:16452677

Sorensen, Staci A; Rubel, Edwin W

2006-02-01

268

Improved Quantification of Cerebral Hemodynamics Using Individualized Time Thresholds for Assessment of Peak Enhancement Parameters Derived from Dynamic Susceptibility Contrast Enhanced Magnetic Resonance Imaging  

PubMed Central

Purpose Assessment of cerebral ischemia often employs dynamic susceptibility contrast enhanced magnetic resonance imaging (DSC-MRI) with evaluation of various peak enhancement time parameters. All of these parameters use a single time threshold to judge the maximum tolerable peak enhancement delay that is supposed to reliably differentiate sufficient from critical perfusion. As the validity of this single threshold approach still remains unclear, in this study, (1) the definition of a threshold on an individual patient-basis, nevertheless (2) preserving the comparability of the data, was investigated. Methods The histogram of time-to-peak (TTP) values derived from DSC-MRI, the so-called TTP-distribution curve (TDC), was modeled using a double-Gaussian model in 61 patients without severe cerebrovascular disease. Particular model-based zf-scores were used to describe the arterial, parenchymal and venous bolus-transit phase as time intervals Ia,p,v. Their durations (delta Ia,p,v), were then considered as maximum TTP-delays of each phase. Results Mean-R2 for the model-fit was 0.967. Based on the generic zf-scores the proposed bolus transit phases could be differentiated. The Ip-interval reliably depicted the parenchymal bolus-transit phase with durations of 3.4 s–10.1 s (median?=?4.3s), where an increase with age was noted (?30 ms/year). Conclusion Individual threshold-adjustment seems rational since regular bolus-transit durations in brain parenchyma obtained from the TDC overlap considerably with recommended critical TTP-thresholds of 4 s–8 s. The parenchymal transit time derived from the proposed model may be utilized to individually correct TTP-thresholds, thereby potentially improving the detection of critical perfusion. PMID:25521121

Nasel, Christian; Kalcher, Klaudius; Boubela, Roland; Moser, Ewald

2014-01-01

269

Input Variable Selection for Hydrologic Modeling Using Anns  

NASA Astrophysics Data System (ADS)

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

Ganti, R.; Jain, A.

2011-12-01

270

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

271

Constrained least-squares image restoration filters for sampled image data  

NASA Astrophysics Data System (ADS)

Constrained least-squares image restoration, first proposed by Hunt twenty years ago, is a linear image restoration technique in which the smoothness of the restored image is maximized subject to a constraint on the fidelity of the restored image. The traditional derivation and implementation of the constrained least-squares restoration (CLS) filter is based on an incomplete discrete/discrete (d/d) system model which does not account for the effects of spatial sampling and image reconstruction. For many imaging systems, these effects are significant and should not be ignored. In a 1990 SPIE paper, Park et. al. demonstrated that a derivation of the Wiener filter based on the incomplete d/d model can be extended to a more comprehensive end-to-end, continuous/discrete/continuous (c/d/c) model. In a similar 1992 SPIE paper, Hazra et al. attempted to extend Hunt's d/d model-based CLS filter derivation to the c/d/c model, but with limited success. In this paper, a successful extension of the CLS restoration filter is presented. The resulting new CLS filter is intuitive, effective and based on a rigorous derivation. The issue of selecting the user-specified inputs for this new CLS filter is discussed in some detail. In addition, we present simulation-based restoration examples for a FLIR (Forward Looking Infra-Red) imaging system to demonstrate the effectiveness of this new CLS restoration filter.

Hazra, Rajeeb; Park, Stephen K.; Smith, G. Louis; Reichenbach, Stephen E.

1993-10-01

272

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

273

Portfolio Selection with Qualitative Input Anant Chiarawongsea  

E-print Network

Portfolio Selection with Qualitative Input Anant Chiarawongsea , Seksan Kiatsupaibulb, , Sunti and Accountancy, Chulalongkorn University, Bangkok 10330, Thailand c Department of Management Science problem that accommo- dates qualitative input about expected returns and provide an algorithm that solves

Van Roy, Ben

274

SYNAPTIC MECHANISMS BDNF and NT-3 increase excitatory input connectivity in rat  

E-print Network

SYNAPTIC MECHANISMS BDNF and NT-3 increase excitatory input connectivity in rat hippocampal Institute of Science, Rehovot, 76100 Israel Keywords: BDNF, network connectivity, NT-3, percolation, synaptic connectivity Abstract The neurotrophic factors brain-derived neurotrophic factor (BDNF

Moses, Elisha

275

77 FR 54902 - Proposed Information Collection; Comment Request; Input From Hawaii's Boat-based Anglers  

Federal Register 2010, 2011, 2012, 2013

...Collection; Comment Request; Input From Hawaii's Boat-based Anglers AGENCY: National...National Data Standards. The State of Hawaii is developing a comprehensive data collection...fishing catch and effort derived from Hawaii's private boaters--a required...

2012-09-06

276

Capacity of Power Constrained Memoryless AWGN Channels with Fixed Input Constellations  

E-print Network

Capacity of Power Constrained Memoryless AWGN Channels with Fixed Input Constellations #3; Nedeljko constellation constraint and 2) a maximum power constraint. We also consider nearly optimal codes derived from

Kavcic, Aleksandar

277

Quantitative prediction of radio frequency induced local heating derived from measured magnetic field maps in magnetic resonance imaging: A phantom validation at 7 T  

NASA Astrophysics Data System (ADS)

Electrical Properties Tomography (EPT) technique utilizes measurable radio frequency (RF) coil induced magnetic fields (B1 fields) in a Magnetic Resonance Imaging (MRI) system to quantitatively reconstruct the local electrical properties (EP) of biological tissues. Information derived from the same data set, e.g., complex numbers of B1 distribution towards electric field calculation, can be used to estimate, on a subject-specific basis, local Specific Absorption Rate (SAR). SAR plays a significant role in RF pulse design for high-field MRI applications, where maximum local tissue heating remains one of the most constraining limits. The purpose of the present work is to investigate the feasibility of such B1-based local SAR estimation, expanding on previously proposed EPT approaches. To this end, B1 calibration was obtained in a gelatin phantom at 7 T with a multi-channel transmit coil, under a particular multi-channel B1-shim setting (B1-shim I). Using this unique set of B1 calibration, local SAR distribution was subsequently predicted for B1-shim I, as well as for another B1-shim setting (B1-shim II), considering a specific set of parameter for a heating MRI protocol consisting of RF pulses plaid at 1% duty cycle. Local SAR results, which could not be directly measured with MRI, were subsequently converted into temperature change which in turn were validated against temperature changes measured by MRI Thermometry based on the proton chemical shift.

Zhang, Xiaotong; Van de Moortele, Pierre-Francois; Liu, Jiaen; Schmitter, Sebastian; He, Bin

2014-12-01

278

Longitudinal monitoring adipose-derived stem cell survival by PET imaging hexadecyl-4-(124)I-iodobenzoate in rat myocardial infarction model.  

PubMed

This study aims to monitor how the change of cell survival of transplanted adipose-derived stem cells (ADSCs) responds to myocardial infarction (MI) via the hexadecyl-4-(124)I-iodobenzoate ((124)I-HIB) mediated direct labeling method in vivo. Stem cells have shown the potential to improve cardiac function after MI. However, monitoring of the fate of transplanted stem cells at target sites is still unclear. Rat ADSCs were labeled with (124)I-HIB, and radiolabeled ADSCs were transplanted into the myocardium of normal and MI model. In the group of (124)I-HIB-labeled ADSC transplantation, in vivo imaging was performed using small-animal positron emission tomography (PET)/computed tomography (CT) for 9days. Twenty-one days post-transplantation, histopathological analysis and apoptosis assay were performed. ADSC viability and differentiation were not affected by (124)I-HIB labeling. In vivo tracking of the (124)I-HIB-labeled ADSCs was possible for 9 and 3days in normal and MI model, respectively. Apoptosis of transplanted cells increased in the MI model compared than that in normal model. We developed a direct labeling agent, (124)I-HIB, and first tried to longitudinally monitor transplanted stem cell to MI. This approach may provide new insights on the roles of stem cell monitoring in living bodies for stem cell therapy from pre-clinical studies to clinical trials. PMID:25446095

Kim, Min Hwan; Woo, Sang-Keun; Lee, Kyo Chul; An, Gwang Il; Pandya, Darpan; Park, Noh Won; Nahm, Sang-Soep; Eom, Ki Dong; Kim, Kwang Il; Lee, Tae Sup; Kim, Chan Wha; Kang, Joo Hyun; Yoo, Jeongsoo; Lee, Yong Jin

2015-01-01

279

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. PMID:20722424

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

2010-01-01

280

Input filter compensation for switching regulators  

NASA Technical Reports Server (NTRS)

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

Lee, F. C.

1984-01-01

281

Input Devices for Young Handicapped Children.  

ERIC Educational Resources Information Center

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

Morris, Karen

282

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

283

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

284

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

285

Image quality evaluation using generalized natural image  

Microsoft Academic Search

Most image quality metrics are derived from feature values of specified test charts. However, such test charts can explain only a small portion of the comprehensive performances on image quality of imaging systems. Thus, designers of imaging systems need to check every possible type of natural image to verify the performance even if they check every image quality factor by

Kenji Kagitani

2008-01-01

286

The response of gross nitrogen mineralization to labile carbon inputs  

NASA Astrophysics Data System (ADS)

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

Bengtson, Per

2014-05-01

287

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

288

A Novel Gestural Input Device for Virtual Reality  

Microsoft Academic Search

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

Christoph Maggioni; SIEMENS AG; Otto Hahn

1993-01-01

289

Honeybee navigation: odometry with monocular input.  

PubMed

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

Srinivasan; Zhang; Lehrer

1998-11-01

290

Analytical derivation of distortion constraints and their verification in a learning vector quantization-based target recognition system  

NASA Astrophysics Data System (ADS)

We obtain a novel analytical derivation for distortion-related constraints in a neural network- (NN)-based automatic target recognition (ATR) system. We obtain two types of constraints for a realistic ATR system implementation involving 4-f correlator architecture. The first constraint determines the relative size between the input objects and input correlation filters. The second constraint dictates the limits on amount of rotation, translation, and scale of input objects for system implementation. We exploit these constraints in recognition of targets varying in rotation, translation, scale, occlusion, and the combination of all of these distortions using a learning vector quantization (LVQ) NN. We present the simulation verification of the constraints using both the gray-scale images and Defense Advanced Research Projects Agency's (DARPA's) Moving and Stationary Target Recognition (MSTAR) synthetic aperture radar (SAR) images with different depression and pose angles.

Iftekharuddin, Khan M.; Razzaque, Mohammad A.

2005-06-01

291

Derivatives Page  

NSDL National Science Digital Library

Derivatives are financial securities whose value is derived from another "underlying" financial security. Options, futures, swaps, swaptions, and structured notes are all examples of derivative securities. Derivatives can be used in hedging, protecting against financial risk, or can be used to speculate on the movement of commodity or security prices, interest rates, or the levels of financial indices. The valuation of derivatives makes use of the statistical mathematics of uncertainty. With links to related articles. See also Derivatives Concepts A-Z, glossary of derivatives-related terminology designed to make the other articles in the Financial Pipeline's Derivatives section easier to understand.

292

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

293

Synthesis and preclinical evaluation of a new C-6 alkylated pyrimidine derivative as a PET imaging agent for HSV1-tk gene expression  

PubMed Central

[18F]FHOMP (6-((1-[18F]-fluoro-3-hydroxypropan-2-yloxy)methyl)-5-methylpyrimidine-2,4(1H,3H)-dione), a C-6 substituted pyrimidine derivative, has been synthesized and evaluated as a potential PET agent for imaging herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene expression. [18F]FHOMP was prepared by the reaction of the tosylated precursor with tetrabutylammonium [18F]-fluoride followed by acidic cleavage of the protecting groups. In vitro cell accumulation of [18F]FHOMP and [18F]FHBG (reference) was studied with HSV1-tk transfected HEK293 (HEK293TK+) cells. Small animal PET and biodistribution studies were performed with HEK293TK+ xenograft-bearing nude mice. The role of equilibrative nucleoside transporter 1 (ENT1) in the transport and uptake of [18F] FHOMP was also examined in nude mice after treatment with ENT1 inhibitor nitrobenzylmercaptopurine ribonucleoside phosphate (NBMPR-P). [18F]FHOMP was obtained in a radiochemical yield of ~25% (decay corrected) and the radiochemical purity was greater than 95%. The uptake of [18F]FHOMP in HSV1-TK containing HEK293TK+ cells was 52 times (at 30 min) and 244 times (at 180 min) higher than in control HEK293 cells. The uptake ratios between HEK293TK+ and HEK293 control cells for [18F]FHBG were significantly lower i.e. 5 (at 30 min) and 81 (240 min). In vivo, [18F]FHOMP accumulated to a similar extend in HEK293TK+ xenografts as [18F]FHBG but with a higher general background. Blocking of ENT1 reduced [18F]FHOMP uptake into brain from a standardized uptake value (SUV) of 0.10±0.01 to 0.06±0.02, but did not reduce the general background signal in PET. Although [18F]FHOMP does not outperform [18F]FHBG in its in vivo performance, this novel C-6 pyrimidine derivative may be a useful probe for monitoring HSV1-tk gene expression in vivo. PMID:23342302

Müller, Ursina; Ross, Tobias L; Ranadheera, Charlene; Slavik, Roger; Müller, Adrienne; Born, Mariana; Trauffer, Evelyn; Sephton, Selena Milicevic; Scapozza, Leonardo; Krämer, Stefanie D; Ametamey, Simon M

2013-01-01

294

PREVIMER : Meteorological inputs and outputs  

NASA Astrophysics Data System (ADS)

PREVIMER is a pre-operational system aiming to provide a wide range of users, from private individuals to professionals, with short-term forecasts about the coastal environment along the French coastlines bordering the English Channel, the Atlantic Ocean, and the Mediterranean Sea. Observation data and digital modelling tools first provide 48-hour (probably 96-hour by summer 2009) forecasts of sea states, currents, sea water levels and temperatures. The follow-up of an increasing number of biological parameters will, in time, complete this overview of coastal environment. Working in partnership with the French Naval Hydrographic and Oceanographic Service (Service Hydrographique et Océanographique de la Marine, SHOM), the French National Weather Service (Météo-France), the French public science and technology research institute (Institut de Recherche pour le Développement, IRD), the European Institute of Marine Studies (Institut Universitaire Européen de la Mer, IUEM) and many others, IFREMER (the French public institute fo marine research) is supplying the technologies needed to ensure this pertinent information, available daily on Internet at http://www.previmer.org, and stored at the Operational Coastal Oceanographic Data Centre. Since 2006, PREVIMER publishes the results of demonstrators assigned to limited geographic areas and to specific applications. This system remains experimental. The following topics are covered : Hydrodynamic circulation, sea states, follow-up of passive tracers, conservative or non-conservative (specifically of microbiological origin), biogeochemical state, primary production. Lastly, PREVIMER provides researchers and R&D departments with modelling tools and access to the database, in which the observation data and the modelling results are stored, to undertake environmental studies on new sites. The communication will focus on meteorological inputs to and outputs from PREVIMER. It will draw the lessons from almost 3 years during which the system has been operational almost everyday and propose perspectives in terms of technical improvements and possible business models.

Ravenel, H.; Lecornu, F.; Kerléguer, L.

2009-09-01

295

Turn customer input into innovation.  

PubMed

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

Ulwick, Anthony W

2002-01-01

296

Programmable remapper for image processing  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

297

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. PMID:19624097

Åslund, Andreas; Sigurdson, Christina J.; Klingstedt, Therése; 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; Hammarström, Per; Nilsson, K. Peter R.

2010-01-01

298

Radiative forcing by aerosols over the Bay of Bengal region derived from shipborne, island-based, and satellite (Moderate-Resolution Imaging Spectroradiometer) observations  

NASA Astrophysics Data System (ADS)

Measurements of spectral aerosol optical depths (AODs) were made over the Bay of Bengal region (adjacent to the Indian landmass) on board the oceanographic research vessel Sagar Kanya during February 2003. Simultaneous measurements of spectral AODs and mass concentrations of the composite aerosols and aerosol black carbon (BC) were made at an island location, Port Blair (11.63°N, 92.71°E), also in the Bay of Bengal. At the cruise locations the AODs were in the range of ˜0.3-0.6 at 500 nm (with a mean value of 0.41 ± 0.14) and Angstrom wavelength exponent of ˜1.1 ± 0.1; while at Port Blair the AODs were in the range of 0.11-0.48 at 500 nm and Angstrom wavelength exponent of 0.98 ± 0.07. Aerosol BC constituted 5.8 ± 0.6% of the composite aerosol mass concentration with a single-scattering albedo of ˜0.88, indicating the presence of a significant amount of submicron absorbing aerosols. Comparisons of AODs measured at Port Blair during cruise 188 and an earlier cruise (cruise 161B) during March 2001 (over the Bay of Bengal, Arabian Sea, and Indian Ocean) with those derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) (on board the TERRA platform) showed excellent agreement with a mean difference of ˜0.01 and a root-mean-square difference of ˜0.03. Regionally averaged aerosol (net) forcing over the Bay of Bengal was in the range -15 to -24 W m-2 at the surface and -2 to -4 W m-2 at the top of the atmosphere in February 2003; these values were smaller in magnitude than those observed over this region during March 2001 and larger than that observed over the Arabian Sea and the Indian Ocean. The resulting atmospheric heating due to aerosol absorption was ˜0.5°K/d.

Vinoj, V.; Babu, S. Suresh; Satheesh, S. K.; Moorthy, K.; Kaufman, Y. J.

2004-03-01

299

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

300

Input estimation from measured structural response  

SciTech Connect

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

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

2009-01-01

301

Evaluation of limited blood sampling population input approaches for kinetic quantification of [18F]fluorothymidine PET data  

PubMed Central

Background Quantification of kinetic parameters of positron emission tomography (PET) imaging agents normally requires collecting arterial blood samples which is inconvenient for patients and difficult to implement in routine clinical practice. The aim of this study was to investigate whether a population-based input function (POP-IF) reliant on only a few individual discrete samples allows accurate estimates of tumour proliferation using [18F]fluorothymidine (FLT). Methods Thirty-six historical FLT-PET data with concurrent arterial sampling were available for this study. A population average of baseline scans blood data was constructed using leave-one-out cross-validation for each scan and used in conjunction with individual blood samples. Three limited sampling protocols were investigated including, respectively, only seven (POP-IF7), five (POP-IF5) and three (POP-IF3) discrete samples of the historical dataset. Additionally, using the three-point protocol, we derived a POP-IF3M, the only input function which was not corrected for the fraction of radiolabelled metabolites present in blood. The kinetic parameter for net FLT retention at steady state, Ki, was derived using the modified Patlak plot and compared with the original full arterial set for validation. Results Small percentage differences in the area under the curve between all the POP-IFs and full arterial sampling IF was found over 60 min (4.2%-5.7%), while there were, as expected, larger differences in the peak position and peak height. A high correlation between Ki values calculated using the original arterial input function and all the population-derived IFs was observed (R2 = 0.85-0.98). The population-based input showed good intra-subject reproducibility of Ki values (R2 = 0.81-0.94) and good correlation (R2 = 0.60-0.85) with Ki-67. Conclusions Input functions generated using these simplified protocols over scan duration of 60 min estimate net PET-FLT retention with reasonable accuracy. PMID:22444834

2012-01-01

302

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 E.

1995-05-01

303

Supporting Incremental Join Queries on Ranked Inputs  

Microsoft Academic Search

This paper investigates the problem of incremen- tal joins of multiple ranked data sets when the join condition is a list of arbitrary user-defined predi- cates on the input tuples. This problem arises in many important applications dealing with ordered inputs and multiple ranked data sets, and requiring the top solutions. We use multimedia applica- tions as the motivating examples

Apostol Natsev; Yuan-chi Chang; John R. Smith; Chung-sheng Li; Jeffrey Scott Vitter

2001-01-01

304

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

305

Modality of Input and Vocabulary Acquisition  

ERIC Educational Resources Information Center

This study examines the effect of input modality (video, audio, and captions, i.e., on-screen text in the same language as audio) on (a) the learning of written and aural word forms, (b) overall vocabulary gains, (c) attention to input, and (d) vocabulary learning strategies of beginning L2 learners. Twenty-six second-semester learners of Russian…

Sydorenko, Tetyana

2010-01-01

306

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

307

Input Effects within a Constructionist Framework  

ERIC Educational Resources Information Center

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

Boyd, Jeremy K.; Goldberg, Adele E.

2009-01-01

308

The design space of input devices  

Microsoft Academic Search

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

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

1990-01-01

309

EDP Applications to Musical Bibliography: Input Considerations  

ERIC Educational Resources Information Center

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

Robbins, Donald C.

1972-01-01

310

FURTHER FACTS ABOUT INPUT TO STATE STABILIZATION  

Microsoft Academic Search

Previous results about input to state stabilizability are shown to hold even for systems which are not linear in controls, provided that a more general type of feedback be allowed. Applications to certain stabilization problems and coprime factorizations, as well as comparisons to other results on input to state stability, are also briefly discussed.

Eduardo D. Sontag

1989-01-01

311

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

312

Computing Functions by Approximating the Input  

ERIC Educational Resources Information Center

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

Goldberg, Mayer

2012-01-01

313

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

314

Statistical identification of effective input variables. [SCREEN  

SciTech Connect

A statistical sensitivity analysis procedure has been developed for ranking the input data of large computer codes in the order of sensitivity-importance. The method is economical for large codes with many input variables, since it uses a relatively small number of computer runs. No prior judgemental elimination of input variables is needed. The sceening method is based on stagewise correlation and extensive regression analysis of output values calculated with selected input value combinations. The regression process deals with multivariate nonlinear functions, and statistical tests are also available for identifying input variables that contribute to threshold effects, i.e., discontinuities in the output variables. A computer code SCREEN has been developed for implementing the screening techniques. The efficiency has been demonstrated by several examples and applied to a fast reactor safety analysis code (Venus-II). However, the methods and the coding are general and not limited to such applications.

Vaurio, J.K.

1982-09-01

315

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

316

A new synthesis for terrestrial nitrogen inputs  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

317

Pulse Input Sequences for Residual Vibration Reduction  

NASA Astrophysics Data System (ADS)

Preshaping of the input is a well known technique to reduce the vibration in a flexible structure. In this paper, inputs in the form of pulse sequences that are able to reduce the residual vibration in overhead crane are presented. If the exact natural frequency and damping ratio of the system are known, then the residual vibration can be eliminated completely. However, additional constraints can be imposed to incorporate some robustness in the system to variations in the natural frequency and damping ratio for practical implementation. Simulation results and experimental tests show that the inputs developed here are effective in moving the system with no or little residual vibration. In addition, the suggested inputs with robustness incorporated show marked insensitivity to errors in natural frequency and damping ratio estimates.

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

1998-03-01

318

Watfactory Virtual Manufacturing Process Varying Inputs  

E-print Network

process for automobile camshafts and has a number of processing steps and many inputs ­ see process map investigation, i.e. when and how many parts to select, what characteristics to measure/change, etc. · Models

Zhu, Mu

319

An input-output stability analysis of a fuzzy controller for a missile autopilot's yaw axis  

Microsoft Academic Search

This paper develops an input-output stability analysis on the basis of the rules, and the control input values generated by the fuzzy controller for each “cell partition” of the phase plane. It is assumed that the rule-base has been designed for a linear plant whose approximate model is available. Furthermore, the rules may have been derived using the operator manual-type

S. S. Farinwata; D. Pirovolou; G. J. Vachtsevanos

1994-01-01

320

Quantization noise in single-loop sigma-delta modulation with sinusoidal inputs  

Microsoft Academic Search

An exact nonlinear difference equation is derived and solved for a simple sigma-delta modulator consisting of a discrete-time integrator and a binary quantizer inside a single feedback loop and an arbitrary input signal. It is shown that the system can be represented as an affine operation (discrete-time integration of a biased input) followed by a memoryless nonlinearity. An extension of

ROBERT M. GRAY; W. Chou; P. W. Wong

1989-01-01

321

Variable-Duty-Cycle Control to Achieve High Input Power Factor for DCM Boost PFC Converter  

Microsoft Academic Search

A discontinuous-current-mode (DCM) boost power factor correction (PFC) converter features zero-current turn-on for the switch, no reverse recovery in diode, and constant- frequency operation. However, the input power factor (PF) is rela- tively low when the duty cycle is constant in a half line cycle. This paper derives the expressions of the input current and PF of the DCM boost

Kai Yao; Xinbo Ruan; Xiaojing Mao; Zhihong Ye

2011-01-01

322

Image enhancement by non-linear extrapolation in frequency space  

NASA Technical Reports Server (NTRS)

An input image is enhanced to include spatial frequency components having frequencies higher than those in an input image. To this end, an edge map is generated from the input image using a high band pass filtering technique. An enhancing map is subsequently generated from the edge map, with the enhanced map having spatial frequencies exceeding an initial maximum spatial frequency of the input image. The enhanced map is generated by applying a non-linear operator to the edge map in a manner which preserves the phase transitions of the edges of the input image. The enhanced map is added to the input image to achieve a resulting image having spatial frequencies greater than those in the input image. Simplicity of computations and ease of implementation allow for image sharpening after enlargement and for real-time applications such as videophones, advanced definition television, zooming, and restoration of old motion pictures.

Anderson, Charles H. (Inventor); Greenspan, Hayit K. (Inventor)

1998-01-01

323

Seven habits of highly successful input modelers  

Microsoft Academic Search

Discrete-event simulation models typically have stoch- astic components that mimic the probabilistic nature of the system under consideration. Successful input modeling requires a close match between the input model and the true underlying probabilistic mecha- nism associated with the system. The general ques- tion considered here is how to model an element (e.g., arrival process, service times) in a discrete-event

Lawrence Leemis

1997-01-01

324

Seven Habits Of Highly Successful Input Modelers  

Microsoft Academic Search

Discrete-event simulation models typically have stochastic components thah mimic the probabilistic nature of the system under consideration. Successful input modeling requires a close match between the input model and the true underlying probabilistic mechanism associated with the system. The general question considered here is how to model an element (e.g., arrival process, service times) in a discrete-event simulation given a

Larry Leemis

1997-01-01

325

Multiple-input experimental modal analysis  

NASA Technical Reports Server (NTRS)

The development of experimental modal analysis techniques is reviewed. System and excitation assumptions are discussed. The methods examined include the forced normal mode excitation method, the frequency response function method, the damped complex exponential response method, the Ibrahim time domain approach, the polyreference approach, and mathematical input-output model methods. The current trend toward multiple input utilization in the estimation of system parameters is noted.

Allemang, R. J.; Brown, D. L.

1985-01-01

326

Pre-clinical development of a neutral, estrogen receptor-targeted, tridentate 99mTc(I) estradiol pyridin-2-yl hydrazine derivative for imaging of breast and endometrial cancers  

PubMed Central

Breast and endometrial cancers are the most common invasive malignancies in women with more than 217,000 new diagnoses per year in the United States. These cancers are often classified into two subtypes based upon the expression of the classical estrogen receptor (ER?). In this study, we describe a new structural class of neutral tridentate 99mTc(I)-estradiol-pyridin-2-yl hydrazine derivatives for potential use in breast and endometrial cancer imaging. Methods The 99mTc(I)-estradiol-pyridin-2-yl hydrazine derivative was synthesized using the Sonogashira cross-coupling reaction and radiolabeled using the tricarbonyl approach. Radiochemical purity was assessed by HPLC. Cell binding studies were performed on human breast adenocarcinoma MCF-7 cells. In vivo biodistribution of the 99mTc(I) derivative was performed in virgin female C57BL/6 mice in defined phases of the estrus cycle. Biodistribution and nanoSPECT/CT imaging studies were performed on mice bearing MCF-7 and primary human endometrial tumors. Results Radiochemical analysis demonstrated that the post-purification purity of the 99mTc(I)-estradiol-pyridin-2-yl hydrazine derivative was ? 95% with a specific activity of 47.5 TBq 99mTc/mmol. Cell binding studies yielded a Kd value of 11 ± 1.5 nM. In vivo studies revealed that receptor-mediated uptake was present in all phases of the estrous cycle in reproductive organs and mammary glands but was highest during the diestrous phase of the estrous cycle. Despite high non-specific uptake in the liver, significant receptor-mediated uptake was observed in target tissues and ER-expressing tumors (0.67% for MCF-7 tumors and 0.77% for endometrial tumors). Tumor uptake was reduced by approximately 50% upon coinjection with 17?-estradiol. Conclusion We have characterized a novel neutral tridentate 99mTc(I)-estradiol-pyridin-2-yl hydrazine derivative for potential use in breast and endometrial cancer imaging. This study is a notable achievement and represents the first step on a path towards the design of estrogen-based Tc-labeled tracers with improved targeting and SPECT-imaging characteristics. PMID:18483091

Nayak, Tapan K.; Hathaway, Helen J.; Ramesh, Chinnasamy; Arterburn, Jeffrey B.; Dai, Donghai; Sklar, Larry A.; Norenberg, Jeffrey P.; Prossnitz, Eric R.

2008-01-01

327

Hippocampal phase precession from dual input components.  

PubMed

Phase precession is a well known phenomenon in which a hippocampal place cell will fire action potentials at successively earlier phases (relative to the theta-band oscillations recorded in the local field potential) as an animal moves through the cell's receptive field (also known as a place field). We present a model in which CA1 pyramidal cell spiking is driven by dual input components arising from CA3 and EC3. The receptive fields of these two input components overlap but are offset in space from each other such that as the animal moves through the model place field, action potentials are driven first by the CA3 input component and then the EC3 input component. As CA3 synaptic input is known to arrive in CA1 at a later theta phase than EC3 input (Mizuseki et al., 2009; Montgomery et al., 2009), CA1 spiking advances in phase as the model transitions from CA3-driven spiking to EC3-driven spiking. Here spike phase is a function of animal location, placing our results in agreement with many experimental observations characterizing CA1 phase precession (O'Keefe and Recce, 1993; Huxter et al., 2003; Geisler et al., 2007). We predict that experimental manipulations that dramatically enhance or disrupt activity in either of these areas should have a significant effect on phase precession observed in CA1. PMID:23175823

Chance, Frances S

2012-11-21

328

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

329

Input filter compensation for switching regulators  

NASA Technical Reports Server (NTRS)

A novel input filter compensation scheme for a buck regulator that eliminates the interaction between the input filter output impedance and the regulator control loop is presented. The scheme is implemented using a feedforward loop that senses the input filter state variables and uses this information to modulate the duty cycle signal. The feedforward design process presented is seen to be straightforward and the feedforward easy to implement. Extensive experimental data supported by analytical results show that significant performance improvement is achieved with the use of feedforward in the following performance categories: loop stability, audiosusceptibility, output impedance and transient response. The use of feedforward results in isolating the switching regulator from its power source thus eliminating all interaction between the regulator and equipment upstream. In addition the use of feedforward removes some of the input filter design constraints and makes the input filter design process simpler thus making it possible to optimize the input filter. The concept of feedforward compensation can also be extended to other types of switching regulators.

Kelkar, S. S.; Lee, F. C.

1983-01-01

330

Hydrologic modeling with uncertain input parameters  

NASA Astrophysics Data System (ADS)

Erosion risk is recognized as a major threat whose consequences affect urbanized and agricultural areas. Recent assessments of the predictive abilities of erosion models show the difficulty to correctly predict the spatial patterns of erosion and deposition. This is due to the high sensibility of the model to input parameters that contain large spatial and temporal variability. Many studies concluded that model outputs are very sensitive to input hydrological parameters, especially to the saturated hydraulic conductivity. Here, we use an erosion model coupling the Shallow Water equations with the Hairsine-Rose soil erosion which can integrate different sediment size classes. As the scale of modeling is different from the scale of observed or measured data, we use a stochastic distribution of relevant input parameters to represent the micro-scale. A first part of the study concerns the rainfall/runoff model in which the saturated hydraulic conductivity is considered as an uncertain input parameter. A second part is dedicated to the influence of soil parameters in the erosion model. For each part, we evaluate how uncertainties on the inputs impact the surface runoff or the erosion model outputs during various types of rainfall events. We test different stochastic tools to quantify the propagation of uncertainties (Monte Carlo method, Karhunen-Loève expansion…) and we use numerical test cases representing fields or hillslope to assess the methodology in the context of runoff and soil erosion modeling. Simulation results allow us to know where effort should be concentrated when collecting input parameters and limit output error.

Rousseau, M.; Cerdan, O.; Ern, A.; Le Maître, O.; Sochala, P.

2012-04-01

331

Rapid Airplane Parametric Input Design (RAPID)  

NASA Technical Reports Server (NTRS)

RAPID is a methodology and software system to define a class of airplane configurations and directly evaluate surface grids, volume grids, and grid sensitivity on and about the configurations. A distinguishing characteristic which separates RAPID from other airplane surface modellers is that the output grids and grid sensitivity are directly applicable in CFD analysis. A small set of design parameters and grid control parameters govern the process which is incorporated into interactive software for 'real time' visual analysis and into batch software for the application of optimization technology. The computed surface grids and volume grids are suitable for a wide range of Computational Fluid Dynamics (CFD) simulation. The general airplane configuration has wing, fuselage, horizontal tail, and vertical tail components. The double-delta wing and tail components are manifested by solving a fourth order partial differential equation (PDE) subject to Dirichlet and Neumann boundary conditions. The design parameters are incorporated into the boundary conditions and therefore govern the shapes of the surfaces. The PDE solution yields a smooth transition between boundaries. Surface grids suitable for CFD calculation are created by establishing an H-type topology about the configuration and incorporating grid spacing functions in the PDE equation for the lifting components and the fuselage definition equations. User specified grid parameters govern the location and degree of grid concentration. A two-block volume grid about a configuration is calculated using the Control Point Form (CPF) technique. The interactive software, which runs on Silicon Graphics IRIS workstations, allows design parameters to be continuously varied and the resulting surface grid to be observed in real time. The batch software computes both the surface and volume grids and also computes the sensitivity of the output grid with respect to the input design parameters by applying the precompiler tool ADIFOR to the grid generation program. The output of ADIFOR is a new source code containing the old code plus expressions for derivatives of specified dependent variables (grid coordinates) with respect to specified independent variables (design parameters). The RAPID methodology and software provide a means of rapidly defining numerical prototypes, grids, and grid sensitivity of a class of airplane configurations. This technology and software is highly useful for CFD research for preliminary design and optimization processes.

Smith, Robert E.

1995-01-01

332

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

333

Staring 2-D hadamard transform spectral imager  

DOEpatents

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

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

2006-02-07

334

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

E-print Network

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

Ross, Arun Abraham

335

Assessment of interannual variations in the surface mass balance of 18 Svalbard glaciers from the Moderate Resolution Imaging Spectroradiometer\\/Terra albedo product  

Microsoft Academic Search

We estimate annual anomalies of the surface mass balance of glaciers on Svalbard for the period 2000–2005 (six years), by calculating the so-called “satellite-derived mass balance” (Bsat) from time series of satellite-derived surface albedos. The method needs no other input variables. Surface albedos are extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS)\\/Terra albedo product. We validate the MODIS albedos by

Wouter Greuell; Jack Kohler; Friedrich Obleitner; Piotr Glowacki; Kjetil Melvold; Erik Bernsen; Johannes Oerlemans

2007-01-01

336

Assessment of interannual variations in the surface mass balance of 18 Svalbard glaciers from the Moderate Resolution Imaging Spectroradiometer\\/Terra albedo product  

Microsoft Academic Search

We estimate annual anomalies of the surface mass balance of glaciers on Svalbard for the period 2000-2005 (six years), by calculating the so-called ``satellite-derived mass balance'' (B sat ) from time series of satellite-derived surface albedos. The method needs no other input variables. Surface albedos are extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS)\\/Terra albedo product. We validate the MODIS

Wouter Greuell; Jack Kohler; Friedrich Obleitner; Piotr Glowacki; Kjetil Melvold; Erik Bernsen; Johannes Oerlemans

2007-01-01

337

NeuroMorph: A Toolset for the Morphometric Analysis and Visualization of 3D Models Derived from Electron Microscopy Image Stacks.  

PubMed

Serialelectron microscopy imaging is crucial for exploring the structure of cells and tissues. The development of block face scanning electron microscopy methods and their ability to capture large image stacks, some with near isotropic voxels, is proving particularly useful for the exploration of brain tissue. This has led to the creation of numerous algorithms and software for segmenting out different features from the image stacks. However, there are few tools available to view these results and make detailed morphometric analyses on all, or part, of these 3D models. We have addressed this issue by constructing a collection of software tools, called NeuroMorph, with which users can view the segmentation results, in conjunction with the original image stack, manipulate these objects in 3D, and make measurements of any region. This approach to collecting morphometric data provides a faster means of analysing the geometry of structures, such as dendritic spines and axonal boutons. This bridges the gap that currently exists between rapid reconstruction techniques, offered by computer vision research, and the need to collect measurements of shape and form from segmented structures that is currently done using manual segmentation methods. PMID:25240318

Jorstad, Anne; Nigro, Biagio; Cali, Corrado; Wawrzyniak, Marta; Fua, Pascal; Knott, Graham

2015-01-01

338

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

339

Bilateral olfactory sensory input enhances chemotaxis behavior.  

PubMed

Neural comparisons of bilateral sensory inputs are essential for visual depth perception and accurate localization of sounds in space. All animals, from single-cell prokaryotes to humans, orient themselves in response to environmental chemical stimuli, but the contribution of spatial integration of neural activity in olfaction remains unclear. We investigated this problem in Drosophila melanogaster larvae. Using high-resolution behavioral analysis, we studied the chemotaxis behavior of larvae with a single functional olfactory neuron on either the left or right side of the head, allowing us to examine unilateral or bilateral olfactory input. We developed new spectroscopic methods to create stable odorant gradients in which odor concentrations were experimentally measured. In these controlled environments, we observed that a single functional neuron provided sufficient information to permit larval chemotaxis. We found additional evidence that the overall accuracy of navigation is enhanced by the increase in the signal-to-noise ratio conferred by bilateral sensory input. PMID:18157126

Louis, Matthieu; Huber, Thomas; Benton, Richard; Sakmar, Thomas P; Vosshall, Leslie B

2008-02-01

340

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

341

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

2013-06-12

342

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

PubMed Central

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

Simoncic, Urban; Jeraj, Robert

2011-01-01

343

Scaling of increased dissolved organic carbon inputs by forest clear-cutting - What arrives downstream?  

NASA Astrophysics Data System (ADS)

Forest clear-cutting has been found to significantly increase concentrations of dissolved organic carbon (DOC) in boreal first-order streams. Here, we address the questions of 1) how the additional inputs of DOC by upstream forest harvesting affect downstream locations within a stream network and 2) what catchment area has to be harvested to cause a significant downstream increase in DOC concentration. We combined the use of primary data from a paired-catchment experiment, clear-cut history of a nested stream network derived from satellite images with a mixing-model approach in order to quantify the importance of upstream clear-cuts on two downstream sites with different catchment sizes. Modeled [DOC] agreed well with the measured concentrations in the smaller, 8.7 km2 catchment located above a larger wetland area, but discrepancies occurred for the larger 22.9 km2 catchment located downstream of the wetland. Estimates of the critical area (Acritical) needed to be harvested to cause a significant impact on downstream DOC concentrations was quantified to be 11% for p

Schelker, Jakob; Öhman, Karin; Löfgren, Stefan; Laudon, Hjalmar

2014-05-01

344

DO MODEL UNCERTAINTY WITH CORRELATED INPUTS  

EPA Science Inventory

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

345

Contemporary Mathematics Nonlinear Input-Output Equilibrium  

E-print Network

and study Nonlinear Input-Output Equilibrium (NIOE). The main difference between NIOE and the classical of productive sectors of an economy. Since WW2 the IO model has been widely used for analysis of economic. The applications of IO range from a branch of a single economy to the World economy. The main contributor to IO

Polyak, Roman A.

346

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 ...

347

Programmable Input for Nanomagnetic Logic Devices  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

348

Numerical simulation of LIGO input optics  

NASA Astrophysics Data System (ADS)

Numerical analysis has been carried out to understand the performance of the Input Optics used in the first generation of LIGO (Laser Interferometer Gravitational-wave Observatory) detector. The input optics is a subsystem consisting of a mode cleaner and mode-matching telescope, where all the optics are suspended and installed in vacuum. Using the end-to-end package (LIGO programming language), computer codes have been made to simulate the input optics. Giving realistic seismic noise to the suspension point of the optics and using the length sensing/alignment sensing control for the mode cleaner, the performance of the input optics has been simulated under various scenarios such as with an order of magnitude higher seismic noise than the normal level, and with/without the alignment sensing control feedback from the arm cavity to the mode-matching telescope. The results are assessed in terms of the beam pointing fluctuation of the laser beam going into the arm cavities, and its influence on the optical coupling to the arm cavities and the noise level at the gravitational wave port signal.

None, Shivanand; Jamal, Nafis; Yoshida, Sanichiro

2005-11-01

349

Consanguine Calculations Input File: blood.in  

E-print Network

1 of 20 Problem A+ Consanguine Calculations Input File: blood.in Every person's blood has 2 markers in a particular ABO blood type for that person. Combination ABO Blood Type AA A AB AB AO A BB B BO B OO O Likewise, every person has two alleles for the blood Rh factor, represented by the characters + and -. Someone who

California at Berkeley, University of

350

SWAT 2012 Input/Output Documentation  

E-print Network

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

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

2013-03-04

351

Rotary Drive Mechanism Accepts Two Inputs  

NASA Technical Reports Server (NTRS)

Mechanism connects two drives to single output shaft without clutches or planetary gears. More reliable than clutch-based two-drive mechanism and less bulky than planetary mechanism. Moreover, designed for any ratio of output to input speed, including an 1:1 ratio, unlike planetary gears. Drives operate simultaneously or separately.

Webster, Larry D.

1987-01-01

352

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

353

Towards Touching Interaction: A Simple Explicit Input  

Microsoft Academic Search

AmI proposes a new way of thinking about computers which follows the ideas of the Ubiquitous Computing vision of Mark Weiser. In these, there is what is known as a Disappearing Computer Initiative, with users immersed in intelligent environments. Hence, technologies need to be adapted so that they are capable of replacing the traditional inputs to the system by embedding

Gabriel Chavira; Salvador W. Nava; Ramón Hervás; José Bravo; C. Sanchez

2007-01-01

354

Input and Intake in Language Acquisition  

ERIC Educational Resources Information Center

This dissertation presents an approach for a productive way forward in the study of language acquisition, sealing the rift between claims of an innate linguistic hypothesis space and powerful domain general statistical inference. This approach breaks language acquisition into its component parts, distinguishing the input in the environment from…

Gagliardi, Ann C.

2012-01-01

355

Adaptive Random Testing with Combinatorial Input Domain  

PubMed Central

Random testing (RT) is a fundamental testing technique to assess software reliability, by simply selecting test cases in a random manner from the whole input domain. As an enhancement of RT, adaptive random testing (ART) has better failure-detection capability and has been widely applied in different scenarios, such as numerical programs, some object-oriented programs, and mobile applications. However, not much work has been done on the effectiveness of ART for the programs with combinatorial input domain (i.e., the set of categorical data). To extend the ideas to the testing for combinatorial input domain, we have adopted different similarity measures that are widely used for categorical data in data mining and have proposed two similarity measures based on interaction coverage. Then, we propose a new version named ART-CID as an extension of ART in combinatorial input domain, which selects an element from categorical data as the next test case such that it has the lowest similarity against already generated test cases. Experimental results show that ART-CID generally performs better than RT, with respect to different evaluation metrics. PMID:24772036

Lu, Yansheng

2014-01-01

356

Multichannel analyzers at high rates of input  

NASA Technical Reports Server (NTRS)

Multichannel analyzer, used with a gating system incorporating pole-zero compensation, pile-up rejection, and baseline-restoration, achieves good resolution at high rates of input. It improves resolution, reduces tailing and rate-contributed continuum, and eliminates spectral shift.

Rudnick, S. J.; Strauss, M. G.

1969-01-01

357

Tracing anthropogenic inputs of nitrogen to ecosystems  

E-print Network

375 CHAPTER 12 Tracing anthropogenic inputs of nitrogen to ecosystems CAROL KENDALL, EMILY M, often followed by fish-kills, due to oxygen deple- tion. Increased atmospheric loads of anthropogenic to become acidified. Still more streams that are not yet chronically acidic could undergo acidic episodes

Elliott, Emily M.

358

New Imaging Modalities in Bone  

Microsoft Academic Search

The digital era has witnessed an exponential growth in bone imaging as new modalities and analytic techniques improve the\\u000a potential for noninvasive study of bone anatomy, physiology, and pathophysiology. Bone imaging very much lends itself to input\\u000a across medical and engineering disciplines. It is in part a reflection of this multidisciplinary input that developments in\\u000a the field of bone imaging

James F. Griffith; Harry K. Genant

2011-01-01

359

Deriving the Intrahepatic Arteriovenous Shunt Rate from CT Images and Biochemical Data Instead of from Arterial Perfusion Scintigraphy in Hepatic Arterial Infusion Chemotherapy  

SciTech Connect

The purpose of the present study was to elucidate a method for predicting the intrahepatic arteriovenous shunt rate from computed tomography (CT) images and biochemical data, instead of from arterial perfusion scintigraphy, because adverse exacerbated systemic effects may be induced in cases where a high shunt rate exists. CT and arterial perfusion scintigraphy were performed in patients with liver metastases from gastric or colorectal cancer. Biochemical data and tumor marker levels of 33 enrolled patients were measured. The results were statistically verified by multiple regression analysis. The total metastatic hepatic tumor volume (V{sub metastasized}), residual hepatic parenchyma volume (V{sub residual}; calculated from CT images), and biochemical data were treated as independent variables; the intrahepatic arteriovenous (IHAV) shunt rate (calculated from scintigraphy) was treated as a dependent variable. The IHAV shunt rate was 15.1 {+-} 11.9%. Based on the correlation matrixes, the best correlation coefficient of 0.84 was established between the IHAV shunt rate and V{sub metastasized} (p < 0.01). In the multiple regression analysis with the IHAV shunt rate as the dependent variable, the coefficient of determination (R{sup 2}) was 0.75, which was significant at the 0.1% level with two significant independent variables (V{sub metastasized} and V{sub residual}). The standardized regression coefficients ({beta}) of V{sub metastasized} and V{sub residual} were significant at the 0.1 and 5% levels, respectively. Based on this result, we can obtain a predicted value of IHAV shunt rate (p < 0.001) using CT images. When a high shunt rate was predicted, beneficial and consistent clinical monitoring can be initiated in, for example, hepatic arterial infusion chemotherapy.

Ozaki, Toshiro, E-mail: ganronbun@amail.plala.or.jp; Seki, Hiroshi; Shiina, Makoto [Niigata Cancer Center Hospital, Department of Radiology (Japan)

2009-09-15

360

Deriving the intrahepatic arteriovenous shunt rate from CT images and biochemical data instead of from arterial perfusion scintigraphy in hepatic arterial infusion chemotherapy.  

PubMed

The purpose of the present study was to elucidate a method for predicting the intrahepatic arteriovenous shunt rate from computed tomography (CT) images and biochemical data, instead of from arterial perfusion scintigraphy, because adverse exacerbated systemic effects may be induced in cases where a high shunt rate exists. CT and arterial perfusion scintigraphy were performed in patients with liver metastases from gastric or colorectal cancer. Biochemical data and tumor marker levels of 33 enrolled patients were measured. The results were statistically verified by multiple regression analysis. The total metastatic hepatic tumor volume (V(metastasized)), residual hepatic parenchyma volume (V(residual); calculated from CT images), and biochemical data were treated as independent variables; the intrahepatic arteriovenous (IHAV) shunt rate (calculated from scintigraphy) was treated as a dependent variable. The IHAV shunt rate was 15.1 +/- 11.9%. Based on the correlation matrixes, the best correlation coefficient of 0.84 was established between the IHAV shunt rate and V(metastasized) (p < 0.01). In the multiple regression analysis with the IHAV shunt rate as the dependent variable, the coefficient of determination (R (2)) was 0.75, which was significant at the 0.1% level with two significant independent variables (V(metastasized) and V(residual)). The standardized regression coefficients (beta) of V(metastasized) and V(residual) were significant at the 0.1 and 5% levels, respectively. Based on this result, we can obtain a predicted value of IHAV shunt rate (p < 0.001) using CT images. When a high shunt rate was predicted, beneficial and consistent clinical monitoring can be initiated in, for example, hepatic arterial infusion chemotherapy. PMID:19484290

Ozaki, Toshiro; Seki, Hiroshi; Shiina, Makoto

2009-09-01

361

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

362

Long term functional plasticity of sensory inputs mediated by olfactory learning  

PubMed Central

Sensory inputs are remarkably organized along all sensory pathways. While sensory representations are known to undergo plasticity at the higher levels of sensory pathways following peripheral lesions or sensory experience, less is known about the functional plasticity of peripheral inputs induced by learning. We addressed this question in the adult mouse olfactory system by combining odor discrimination studies with functional imaging of sensory input activity in awake mice. Here we show that associative learning, but not passive odor exposure, potentiates the strength of sensory inputs up to several weeks after the end of training. We conclude that experience-dependent plasticity can occur in the periphery of adult mouse olfactory system, which should improve odor detection and contribute towards accurate and fast odor discriminations. DOI: http://dx.doi.org/10.7554/eLife.02109.001 PMID:24642413

Abraham, Nixon M; Vincis, Roberto; Lagier, Samuel; Rodriguez, Ivan; Carleton, Alan

2014-01-01

363

Postnatal subventricular zone progenitors switch their fate to generate neurons with distinct synaptic input patterns.  

PubMed

New granule cell neurons (GCs) generated in the neonatal and adult subventricular zone (SVZ) have distinct patterns of input synapses in their dendritic domains. These synaptic input patterns determine the computations that the neurons eventually perform in the olfactory bulb. We observed that GCs generated earlier in postnatal life had acquired an 'adult' synaptic development only in one dendritic domain, and only later-born GCs showed an 'adult' synaptic development in both dendritic domains. It is unknown to what extent the distinct synaptic input patterns are already determined in SVZ progenitors and/or by the brain circuit into which neurons integrate. To distinguish these possibilities, we heterochronically transplanted retrovirally labeled SVZ progenitor cells. Once these transplanted progenitors, which mainly expressed Mash1, had differentiated into GCs, their glutamatergic input synapses were visualized by genetic tags. We observed that GCs derived from neonatal progenitors differentiating in the adult maintained their characteristic neonatal synapse densities. Grafting of adult SVZ progenitors to the neonate had a different outcome. These GCs formed synaptic densities that corresponded to neither adult nor neonatal patterns in two dendritic domains. In summary, progenitors in the neonatal and adult brain generate distinct GC populations and switch their fate to generate neurons with specific synaptic input patterns. Once they switch, adult progenitors require specific properties of the circuit to maintain their characteristic synaptic input patterns. Such determination of synaptic input patterns already at the progenitor-cell level may be exploited for brain repair to engineer neurons with defined wiring patterns. PMID:25519243

Ravi, Namasivayam; Li, Zhijun; Oettl, Lars-Lennart; Bartsch, Dusan; Schönig, Kai; Kelsch, Wolfgang

2015-01-15

364

(constrain 4bar ((base-a input)  

E-print Network

gamma3 psi2 psi3) ((Complex? D2) (Complex? D3) (number? phi2) (number? phi3) (number? gamma2) (number? gamma3) (number? psi2) (number? psi3)) (let ((Cphi2 (new Complex (real (cos phi2)) (imag (sin phi2 Complex (real (cos psi2)) (imag (sin psi2)))) (Cpsi3 (new Complex (real (cos psi3)) (imag (sin psi3)))) (Z

Salustri, Filippo A.

365

Clouds of Venus. Input to VIRA.  

NASA Astrophysics Data System (ADS)

Venus is completely covered by a thick clod deck. Its' total optical depth in the visible is equal to 30+/-10. Original VIRA model based on the measurements from Pioneer Venus descent probes and orbiter described mainly cloud particle sizes, properties and their vertical distribution. Later measurements from Venera-15 and Venus Express permitted more detailed studies of horizontal and vertical variations. Imaging of Venus in the UV range shows variety of cloud features that include mottled and streaky clouds in the low latitudes, bright mid-latitude belt and ``polar cap'' with imbedded oval polar dipole. Despite this non-uniform picture the location of the upper boundary of the clouds, derived from the observation of the absorption bands in the reflected IR spectrum, demonstrates a smooth systematic behavior with the latitudinal trends symmetric with respect to equator. In low and middle latitudes the cloud top is located at 72+/-1 km. It decreases poleward of +/-50 degrees and reaches 63--69 km in polar regions. This depression coincides with the eye of the planetary vortex. The effective average particle size radius is equal to (1.3+/-0.5) micron at latitudes of 0--70, with a peak value some 50% larger in the polar regions. Cloud top can experience fast variations of about metricconverterProductID1 km1 km in tens of hours, while larger long-term variations of several kilometers have been observed only at high latitudes. UV markings correlate with the cloud altimetry, however the difference between adjacent UV dark and bright regions never exceeds few hundred meters. Ultraviolet dark spiral arms, which are often seen at about --70 degress, correspond to higher altitudes or to the regions with strong latitudinal gradient of the cloud top altitude. In contrast to the relatively uniform upper cloud boundary, strong variations of the brightness temperature at specific near infrared wavelengths, especially in low latitudes, are related to variations of the cloud thickness in the middle and low cloud decks consistent with significant convective activity at these levels. The morphology of the holes tends from highly variable orientations of features with aspect ratios of nearly one at low latitudes, to very large aspect ratios and zonally oriented features at higher latitudes.

Ignatiev, Nikolay; Zasova, Ludmila

2012-07-01

366

Complex derivatives  

NASA Astrophysics Data System (ADS)

The intrinsic complexity of the financial derivatives market has emerged as both an incentive to engage in it, and a key source of its inherent instability. Regulators now faced with the challenge of taming this beast may find inspiration in the budding science of complex systems.

Battiston, Stefano; Caldarelli, Guido; Georg, Co-Pierre; May, Robert; Stiglitz, Joseph

2013-03-01

367

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

368

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

EPA Science Inventory

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

369

Mixed-Domain Systems and Signal Processing Based on Input Decomposition  

Microsoft Academic Search

Using input decomposition as a starting point, a variety of new types of systems and signal processors, which mix together domains traditionally kept separate, are derived, and their properties are examined. In one of these systems, digital signals are processed in continuous time, thus avoiding sampling and consequent aliasing, while maintaining the advantages of digital implementations in terms of programmability

Yannis Tsividis

2006-01-01

370

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

371

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

NASA Technical Reports Server (NTRS)

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

Ito, Kazufumi; Powers, Robert K.

1987-01-01

372

Influence of streamside vegetation on inputs of terrestrial invertebrates to salmonid food webs  

E-print Network

Influence of streamside vegetation on inputs of terrestrial invertebrates to salmonid food webs J, and spawning migrations. We examined the contribution of terrestrially derived invertebrates (TI) to juvenile of invertebrate mass averaged across all sites; no significant differences associated with location (plant

Wagner, Diane

373

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

2013-10-01

374

Estimating 3D Hand Pose from a Cluttered Image  

Microsoft Academic Search

A method is proposed that can generate a ranked list of plausible three-dimensional hand configurations that best match an input image. Hand pose estimation is formulated as an image database indexing problem, where the closest matches for an input hand image are retrieved from a large database of synthetic hand images. In contrast to previ- ous approaches, the system can

Vassilis Athitsos; Stan Sclaroff

2003-01-01

375

Carbon Arc Image Furnaces  

Microsoft Academic Search

Various optical systems are discussed with reference to their use with carbon arc image furnaces. A new optical system which employs two elliptical mirrors is described and shown to have numerous practical advantages. Using modifications of motion picture projection lamps, measurements have been made of carbon arc image furnaces ranging up to more than 26-kw power input, producing approximately 3000-watts

M. R. Null; W. W. Lozier

1958-01-01

376

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

NASA Astrophysics Data System (ADS)

Reflection seismic imaging faces several difficulties in hard rock environments. One of them is the estimation of the propagation velocity of seismic waves. Therefore, imaging algorithms that do not require prior construction of a velocity model seem promising for such environments. In this paper we illustrate an application of prestack time migration, which does not require an input velocity model, to hard rock conditions, and we demonstrate its effectiveness on synthetic data. This approach is based on an estimation of local event slopes (horizontal slownesses) in common-shot and common-receiver gathers and a subsequent calculation of the migration attributes (migration velocity, vertical traveltime and horizontal coordinates of the migrated reflection point). These attributes allow us to derive all the information needed to construct a time-migrated image. We also use the obtained migration velocities as an input velocity model for Kirchhoff prestack time migration (PSTM) and compare the results of the proposed approach with a conventional Kirchhoff migration using as an input the picked NMO velocity model. This application to a hard rock synthetic model illustrates the potential of the presented migration algorithm for imaging in hard rock seismic exploration. We believe that this approach can be used in hard rock seismic processing workflows as an automatic tool to obtain an input velocity model for the Kirchhoff PSTM.

Tertyshnikov, Konstantin 12Bóna, Andrej 1Pevzner, Roman

2014-09-01

377

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

378

Signaling inputs to invadopodia and podosomes  

PubMed Central

Summary Remodeling of extracellular matrix (ECM) is a fundamental cell property that allows cells to alter their microenvironment and move through tissues. Invadopodia and podosomes are subcellular actin-rich structures that are specialized for matrix degradation and are formed by cancer and normal cells, respectively. Although initial studies focused on defining the core machinery of these two structures, recent studies have identified inputs from both growth factor and adhesion signaling as crucial for invasive activity. This Commentary will outline the current knowledge on the upstream signaling inputs to invadopodia and podosomes and their role in governing distinct stages of these invasive structures. We discuss invadopodia and podosomes as adhesion structures and highlight new data showing that invadopodia-associated adhesion rings promote the maturation of already-formed invadopodia. We present a model in which growth factor stimulation leads to phosphoinositide 3-kinase (PI3K) activity and formation of invadopodia, whereas adhesion signaling promotes exocytosis of proteinases at invadopodia. PMID:23843616

Hoshino, Daisuke; Branch, Kevin M.; Weaver, Alissa M.

2013-01-01

379

Radiofluorinated derivatives of 2-(phosphonomethyl)pentanedioic acid as inhibitors of prostate specific membrane antigen (PSMA) for the imaging of prostate cancer.  

PubMed

For prostate cancer, prostate specific membrane antigen (PSMA) has been identified as a diagnostic and therapeutic target. Fluorinated derivatives of 2-(phosphonomethyl)pentanedioic acid were designed and synthesized to explore whether this fluorine-substituent is tolerated in the pentanedioic acid moiety that is common to almost all PSMA targeting small molecule inhibitors. The binding affinities of the racemic and individual stereoisomers of 2-fluoro-4-(phosphonomethyl)pentanedioic acid were determined and showed that the introduction of fluorine was well tolerated. The radiosynthesis of the analogous 2-[(18)F]fluoro-4-(phosphonomethyl)pentanedioic acid was developed and evaluated in vivo with the PSMA positive LNCaP human prostate cancer cell. The biological results demonstrated specific binding of the tracer to PSMA positive tumors in mice. These results warrant the further evaluation of this class of compounds as radiolabeled tracers for the detection and staging of prostate cancer. PMID:23025786

Graham, Keith; Lesche, Ralf; Gromov, Alexey V; Böhnke, Niels; Schäfer, Martina; Hassfeld, Jorma; Dinkelborg, Ludger; Kettschau, Georg

2012-11-26

380

Image processing and recognition for biological images  

PubMed Central

This paper reviews image processing and pattern recognition techniques, which will be useful to analyze bioimages. Although this paper does not provide their technical details, it will be possible to grasp their main tasks and typical tools to handle the tasks. Image processing is a large research area to improve the visibility of an input image and acquire some valuable information from it. As the main tasks of image processing, this paper introduces gray-level transformation, binarization, image filtering, image segmentation, visual object tracking, optical flow and image registration. Image pattern recognition is the technique to classify an input image into one of the predefined classes and also has a large research area. This paper overviews its two main modules, that is, feature extraction module and classification module. Throughout the paper, it will be emphasized that bioimage is a very difficult target for even state-of-the-art image processing and pattern recognition techniques due to noises, deformations, etc. This paper is expected to be one tutorial guide to bridge biology and image processing researchers for their further collaboration to tackle such a difficult target. PMID:23560739

Uchida, Seiichi

2013-01-01

381

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

PubMed Central

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

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

2014-01-01

382

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

PubMed Central

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

2014-01-01

383

The WIRCam Deep Survey. I. Counts, colours, and mass-functions derived from near-infrared imaging in the CFHTLS deep fields  

NASA Astrophysics Data System (ADS)

We present a new near-infrared imaging survey in the four CFHTLS deep fields: the WIRCam Deep Survey or "WIRDS". WIRDS comprises extremely deep, high quality (FWHM ~ 0.6?) J, H, and Ks imaging covering a total effective area of 2.1 deg2 and reaching AB 50% completeness limits of ? 24.5. We combine our images with the CFHTLS to create a unique eight-band ugrizJHKS photometric catalogues in the four CFHTLS deep fields; these four separate fields allow us to make a robust estimate of the effect of cosmic variance for all our measurements. We use these catalogues in combination with ? 9800 spectroscopic redshifts to estimate precise photometric redshifts (??z/(1 + z) ? 0.03 at i < 25), galaxy types, star-formation rates and stellar masses for a unique sample of ? 1.8 million galaxies. Our JHKs number counts are consistent with previous studies. We apply the "BzK" selection to our gzK filter set and find that the star forming BzK selection successfully selects 76% of star-forming galaxies in the redshift range 1.4 < z < 2.5 in our photometric catalogue, based on our photometric redshift measurement. Similarly the passive BzK selection returns 52% of the passive 1.4 < z < 2.5 population identified in the photometric catalogue. We present the mass functions of the total galaxy population as a function of redshift up to z = 2 and present fits using double Schechter functions. A mass-dependent evolution of the mass function is seen with the numbers of galaxies with masses of M ? 1010.75 still evolving at z ? 1, but galaxies of higher mass reaching their present day numbers by z ~ 0.8-1. This is consistent with the present picture of downsizing in galaxy evolution. We compare our results with the predictions of the GALFORM semi-analytical galaxy formation model and find that the simulations provide a relatively successful fit to the observed mass functions at intermediate masses (i.e. 10 ? log (M/M?) ? 11). However, as is common with semi-analytical predictions of the mass function, the GALFORM results under-predict the mass function at low masses (i.e. log (M/M?) ? 10), whilst the fit as a whole degrades beyondredshifts of z ~ 1.2. All photometric catalogues and images are made publicly available from TERAPIX and CADC. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS.

Bielby, R.; Hudelot, P.; McCracken, H. J.; Ilbert, O.; Daddi, E.; Le Fèvre, O.; Gonzalez-Perez, V.; Kneib, J.-P.; Marmo, C.; Mellier, Y.; Salvato, M.; Sanders, D. B.; Willott, C. J.

2012-09-01

384

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

385

Sensory synergy as environmental input integration  

PubMed Central

The development of a method to feed proper environmental inputs back to the central nervous system (CNS) remains one of the challenges in achieving natural movement when part of the body is replaced with an artificial device. Muscle synergies are widely accepted as a biologically plausible interpretation of the neural dynamics between the CNS and the muscular system. Yet the sensorineural dynamics of environmental feedback to the CNS has not been investigated in detail. In this study, we address this issue by exploring the concept of sensory synergy. In contrast to muscle synergy, we hypothesize that sensory synergy plays an essential role in integrating the overall environmental inputs to provide low-dimensional information to the CNS. We assume that sensor synergy and muscle synergy communicate using these low-dimensional signals. To examine our hypothesis, we conducted posture control experiments involving lateral disturbance with nine healthy participants. Proprioceptive information represented by the changes on muscle lengths were estimated by using the musculoskeletal model analysis software SIMM. Changes on muscles lengths were then used to compute sensory synergies. The experimental results indicate that the environmental inputs were translated into the two dimensional signals and used to move the upper limb to the desired position immediately after the lateral disturbance. Participants who showed high skill in posture control were found to be likely to have a strong correlation between sensory and muscle signaling as well as high coordination between the utilized sensory synergies. These results suggest the importance of integrating environmental inputs into suitable low-dimensional signals before providing them to the CNS. This mechanism should be essential when designing the prosthesis' sensory system to make the controller simpler. PMID:25628523

Alnajjar, Fady; Itkonen, Matti; Berenz, Vincent; Tournier, Maxime; Nagai, Chikara; Shimoda, Shingo

2015-01-01

386

A study in two-handed input  

Microsoft Academic Search

Two experiments were run to investigate two-handed input. The experimental tasks were representative of those found in CAD and office information systems. Experiment one involved the performance of a compound selection\\/positioning task. The two sub-tasks were performed by different hands using separate transducers. Without prompting, novice subjects adopted strategies that involved performing the two sub-tasks simultaneously. We interpret this as

William Buxton; Brad A. Myers

1986-01-01

387

Handling Input on Windows Phone 7  

Microsoft Academic Search

\\u000a Handling input is a critical aspect of any application, but it is an especially unique challenge on a mobile device. The first\\u000a consideration is that the user is most likely not sitting in a comfortable chair sipping coffee, casually browsing the Internet.\\u000a A mobile application user is most likely on the go, looking to just get a task done or

Rob Cameron

388

Level 2 processing for the imaging Fourier transform spectrometer GLORIA: derivation and validation of temperature and trace gas volume mixing ratios from calibrated dynamics mode spectra  

NASA Astrophysics Data System (ADS)

The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an airborne infrared limb-imager combining a two-dimensional infrared detector with a Fourier transform spectrometer. It was operated aboard the new German Gulfstream G550 research aircraft HALO during the Transport And Composition in the upper Troposphere/lowermost Stratosphere (TACTS) and Earth System Model Validation (ESMVAL) campaigns in summer 2012. This paper describes the retrieval of temperature and trace gas (H2O, O3, HNO3) volume mixing ratios from GLORIA dynamics mode spectra. 26 integrated spectral windows are employed in a joint fit to retrieve seven targets using consecutively a fast and an accurate tabulated radiative transfer model. Typical diagnostic quantities are provided including effects of uncertainties in the calibration and horizontal resolution along the line-of-sight. Simultaneous in-situ observations by the BAsic HALO Measurement And Sensor System (BAHAMAS), the Fast In-Situ Stratospheric Hygrometer (FISH), FAIRO, and the Atmospheric chemical Ionization Mass Spectrometer (AIMS) allow a validation of retrieved values for three flights in the upper troposphere/lowermost stratosphere region spanning polar and sub-tropical latitudes. A high correlation is achieved between the remote sensing and the in-situ trace gas data, and discrepancies can to a large fraction be attributed to differences in the probed air masses caused by different sampling characteristics of the instruments. This 1-D processing of GLORIA dynamics mode spectra provides the basis for future tomographic inversions from circular and linear flight paths to better understand selected dynamical processes of the upper troposphere and lowermost stratosphere.

Ungermann, J.; Blank, J.; Dick, M.; Ebersoldt, A.; Friedl-Vallon, F.; Giez, A.; Guggenmoser, T.; Höpfner, M.; Jurkat, T.; Kaufmann, M.; Kaufmann, S.; Kleinert, A.; Krämer, M.; Latzko, T.; Oelhaf, H.; Olchewski, F.; Preusse, P.; Rolf, C.; Schillings, J.; Suminska-Ebersoldt, O.; Tan, V.; Thomas, N.; Voigt, C.; Zahn, A.; Zöger, M.; Riese, M.

2014-12-01

389

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. PMID:20298528

2010-01-01

390

Minimizing structural vibrations with Input Shaping (TM)  

NASA Technical Reports Server (NTRS)

A new method for commanding machines to move with increased dynamic performance was developed. This method is an enhanced version of input shaping, a patented vibration suppression algorithm. This technique intercepts a command input to a system command that moves the mechanical system with increased performance and reduced residual vibration. This document describes many advanced methods for generating highly optimized shaping sequences which are tuned to particular systems. The shaping sequence is important because it determines the trade off between move/settle time of the system and the insensitivity of the input shaping algorithm to variations or uncertainties in the machine which can be controlled. For example, a system with a 5 Hz resonance that takes 1 second to settle can be improved to settle instantaneously using a 0.2 shaping sequence (thus improving settle time by a factor of 5). This system could vary by plus or minus 15% in its natural frequency and still have no apparent vibration. However, the same system shaped with a 0.3 second shaping sequence could tolerate plus or minus 40% or more variation in natural frequency. This document describes how to generate sequences that maximize performance, sequences that maximize insensitivity, and sequences that trade off between the two. Several software tools are documented and included.

Singhose, Bill; Singer, Neil

1995-01-01

391

Molecular structure input on the web.  

PubMed

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. PMID:20298528

Ertl, Peter

2010-01-01

392

Investigation of dynamic SPECT measurements of the arterial input function in human subjects using simulation, phantom and human studies  

Microsoft Academic Search

Computer simulations, a phantom study and a human study were performed to determine whether a slowly rotating single-photon computed emission tomography (SPECT) system could provide accurate arterial input functions for quantification of myocardial perfusion imaging using kinetic models. The errors induced by data inconsistency associated with imaging with slow camera rotation during tracer injection were evaluated with an approach called

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

2012-01-01

393

Stability Analysis of Networked Control Systems with Unknown Inputs  

E-print Network

# , Jitesh H. Panchal and Dengfeng Sun Abstract-- Unknown Input Observers (UIO) use the known plant's inputs robust observers for linear and nonlinear systems, for systems with known and unknown inputsStability Analysis of Networked Control Systems with Unknown Inputs Ahmad F Taha, Ahmed Elmahdi

Sun, Dengfeng

394

Validation of the 3D biogeochemical model MIRO&CO with field nutrient and phytoplankton data and MERIS-derived surface chlorophyll a images  

NASA Astrophysics Data System (ADS)

This paper presents results obtained with MIRO&CO-3D, a biogeochemical model dedicated to the study of eutrophication and applied to the Channel and Southern Bight of the North Sea (48.5°N-52.5°N). The model results from coupling of the COHERENS-3D hydrodynamic model and the biogeochemical model MIRO, which was previously calibrated in a multi-box implementation. MIRO&CO-3D is run to simulate the annual cycle of inorganic and organic carbon and nutrients (nitrogen, phosphorus and silica), phytoplankton (diatoms, nanoflagellates and Phaeocystis), bacteria and zooplankton (microzooplankton and copepods) with realistic forcing (meteorological conditions and river loads) for the period 1991-2003. Model validation is first shown by comparing time series of model concentrations of nutrients, chlorophyll a, diatom and Phaeocystis with in situ data from station 330 (51°26.00'N, 2°48.50'E) located in the centre of the Belgian coastal zone. This comparison shows the model's ability to represent the seasonal dynamics of nutrients and phytoplankton in Belgian waters. However the model fails to simulate correctly the dissolved silica cycle, especially during the beginning of spring, due to the late onset (in the model) of the early spring diatom bloom. As a general trend the chlorophyll a spring maximum is underestimated in simulations. A comparison between the seasonal average of surface winter nutrients and spring chlorophyll a concentrations simulated with in situ data for different stations is used to assess the accuracy of the simulated spatial distribution. At a seasonal scale, the spatial distribution of surface winter nutrients is in general well reproduced by the model with nevertheless a small overestimation for a few stations close to the Rhine/Meuse mouth and a tendency to underestimation in the coastal zone from Belgium to France. PO 4 was simulated best; silica was simulated with less success. Spring chlorophyll a concentration is in general underestimated by the model. The accuracy of the simulated phytoplankton spatial distribution is further evaluated by comparing simulated surface chlorophyll a with that derived from the satellite sensor MERIS for the year 2003. Reasonable agreement is found between simulated and satellite-derived regions of high chlorophyll a with nevertheless discrepancies close to the boundaries.

Lacroix, Geneviève; Ruddick, Kevin; Park, Youngje; Gypens, Nathalie; Lancelot, Christiane

2007-01-01

395

Lineaments derived from analysis of linear features mapped from Landsat images of the Four Corners region of the Southwestern United States  

USGS Publications Warehouse

Linear features are relatively short, distinct, non-cultural linear elements mappable on Landsat multispectral scanner images (MSS). Most linear features are related to local topographic features, such as cliffs, slope breaks, narrow ridges, and stream valley segments that are interpreted as reflecting directed aspects of local geologic structure including faults, zones of fracturing (joints), and the strike of tilted beds. 6,050 linear features were mapped on computer-enhanced Landsat MSS images of 11 Landsat scenes covering an area from the Rio Grande rift zone on the east to the Grand Canyon on the west and from the San Juan Mountains, Colorado, on the north to the Mogollon Rim on the south. Computer-aided statistical analysis of the linear feature data revealed 5 statistically important trend intervals: 1.) N. 10W.-N.16E., 2.) N.35-72E., 3.) N.33-59W., 4.) N. 74-83W., and 5.) N.89-9-W. and N. 89-90E. Subsequent analysis of the distribution of the linear features indicated that only the first three trend intervals are of regional geologic significance. Computer-generated maps of the linear features in each important trend interval were prepared, as well as contour maps showing the relative concentrations of linear features in each trend interval. These maps were then analyzed for patterns suggestive of possible regional tectonic lines. 20 possible tectonic lines, or lineaments, were interpreted from the maps. One lineament is defined by an obvious change in overall linear feature concentrations along a northwest-trending line cutting across northeastern Arizona. Linear features are abundant northeast of the line and relatively scarce to the southwest. The remaining 19 lineaments represent the axes of clusters of parallel linear features elongated in the direction of the linear feature trends. Most of these lineaments mark previously known structural zones controlled by linear features in the Precambrian basement or show newly recognized relationships to geological and/or geophysical patterns that suggest probable influence by buried basement features. The remaining few lineaments are not strongly correlative with geological or geophysical patterns, but on the basis of existing data they cannot be dismissed as being possible expressions of basement features.

Knepper, Daniel H.

1982-01-01

396

Computerized tomography using video recorded fluoroscopic images  

NASA Technical Reports Server (NTRS)

A computerized tomographic imaging system is examined which employs video-recorded fluoroscopic images as input data. By hooking the video recorder to a digital computer through a suitable interface, such a system permits very rapid construction of tomograms.

Kak, A. C.; Jakowatz, C. V., Jr.; Baily, N. A.; Keller, R. A.

1975-01-01

397

One-pot synthesis of highly fluorescent pyrido[1,2-a]indole derivatives through C-H/N-H activation: photophysical investigations and application in cell imaging.  

PubMed

We describe a straightforward strategy for the synthesis of strongly fluorescent pyridoindoles by Pd-catalyzed oxidative annulations of internal alkynes with C-3 functionalized indoles through C?H/N?H bond activation in a one-pot tandem process. Mechanistic investigations reveal the preferential activation of N?H indole followed by C?H activation during the cyclization process. Photophysical properties of pyridoindoles exhibited the highest fluorescence quantum yield of nearly 80?%, with emission color varying from blue to green to orange depending on the substructures. Quantum mechanical calculations provide insights into the observed photophysical properties. The strong fluorescence of the pyrido[1,2-a]indole derivative has been employed in subcellular imaging, which demonstrates its localization in the cell nucleus. PMID:25213659

Samala, Srinivas; Pallavi, Pragyan; Kumar, Ravi; Arigela, Rajesh K; Singh, Gajendra; Ampapathi, Ravi Sankar; Priya, Amulya; Datta, Sunando; Patra, Abhijit; Kundu, Bijoy

2014-10-27

398

Water-soluble tetraphenylethene derivatives as fluorescent "light-up" probes for nucleic acid detection and their applications in cell imaging.  

PubMed

The detection of nucleic acids, such as DNA and RNA, plays a significant role in genetic engineering, forensics, and bioinformatics. Traditional nucleic acid probes are mainly intercalators, which are potential mutagens, or groove binders that show high preference only for double-stranded DNA. We herein present two versatile fluorescent probes for nucleic acid detection and visualization. The nonemissive tetraphenylethene derivatives (TTAPE) are induced by DNA/RNA to emit, thereby showing a novel phenomenon of aggregation-induced emission (AIE). This kind of "light-up" property enables the quantitation and visualization of nucleic acids in aqueous solution and electrophoretic gels, respectively. The cationic TTAPE can penetrate cells with a compromised plasma membrane easily but cannot enter live cells with an intact membrane, thus making them useful for the differentiation between dead and live cells. On account of the high binding affinity to DNA, TTAPE can selectively label the chromosomes and nuclei in fixed cells, which provides a simple and fast method for the observation of cell mitosis. Owing to their AIE characteristics, the dye molecules aggregate in DNA-rich regions and exert appreciable quantum efficiency as well as superior photostability. PMID:23596133

Hong, Yuning; Chen, Sijie; Leung, Chris Wai Tung; Lam, Jacky Wing Yip; Tang, Ben Zhong

2013-08-01

399

Desert Dust Air Mass Mapping in the Western Sahara, using Particle Properties Derived from Space-based Multi-angle Imaging  

NASA Technical Reports Server (NTRS)

Coincident observations made over the Moroccan desert during the SAhara Mineral dUst experiMent (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from Multi-angle Imaging SpectroRadiometer (MISR) observations, and to place the sub-orbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days for which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 to 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR's ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape, and single-scattering albedo. For the three study days, the satellite observations (a) highlight regional gradients in the mix of dust and background spherical particles, (b) identify a dust plume most likely part of a density flow, and (c) show an air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometers away.

Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Fiebig, Marcus; Schladitz, Alexander; von Hoyningen-Huene, Wolfgang

2008-01-01

400

Dephosphorylation of D-Peptide Derivatives to Form Biofunctional, Supramolecular Nanofibers/Hydrogels and Their Potential Applications for Intracellular Imaging and Intratumoral Chemotherapy  

PubMed Central

D-peptides, as the enantiomers of the naturally occurring L-peptides, usually resist endogenous proteases and presumably insensitive to most enzymes. But it is unclear whether or how a phosphatase catalyzes the dephosphorylation from D-peptides. In this work, we examine the formation of the nanofibers of D-peptides via enzymatic dephosphorylation. By comparing the enzymatic hydrogelation of L-peptide and D-peptide based hydrogelators, we find that the chirality of the precursors of the hydrogelators affects little on the enzymatic hydrogelation resulted from the removal of phosphate group from a tyrosine phosphate residue. The attachment of a therapeutic agent (e.g., taxol) or a fluorophore (e.g., 4-nitro-2,1,3-benzoxadiazole (NBD)) to the D-peptide based hydrogelators afford a new type of biostable or biocompatible hydrogelators, which may find applications in intratumoral chemotherapy or intracellular imaging, respectively. This work, as the first comprehensive and systematic study of the unexpected enzymatic dephosphorylation of D-peptides, illustrates a useful approach to generate supramolecular hydrogels that have both biostability and other desired functions. PMID:23742714

Li, Jiayang; Gao, Yuan; Kuang, Yi; Shi, Junfeng; Du, Xuewen; Zhou, Jie; Wang, Huaimin; Yang, Zhimou; Xu, Bing

2013-01-01

401

Comparative live bioluminescence imaging of monkeypox virus dissemination in a wild-derived inbred mouse (Mus musculus castaneus) and outbred African dormouse (Graphiurus kelleni).  

PubMed

Monkeypox virus belongs to the orthopoxvirus genus, infects rodents and monkeys in Africa, produces a smallpox-like zoonotic disease in humans, and has the potential for global spread and exploitation for bioterrorism. Several small animal models for studying monkeypox virus pathogenesis have been investigated. The African dormouse is a candidate natural host but is outbred and no immunological reagents exist. Although not a natural host, the CAST/EiJ mouse is inbred and animals and reagents are commercially available. We compared the dissemination of monkeypox virus by bioluminescence imaging in CAST/EiJ mice and dormice. In CAST/EiJ mice, intense replication occurred at the intranasal site of inoculation and virus spread rapidly to lungs and abdominal organs, which had a lower virus burden. Compared to CAST/EiJ mice, dormice exhibited a greater variation of virus spread, a slower time course, less replication in the head and chest, and more replication in abdominal organs prior to death. PMID:25462355

Earl, Patricia L; Americo, Jeffrey L; Cotter, Catherine A; Moss, Bernard

2015-01-15

402

Interactive specification and acquisition of depth from single images  

E-print Network

We describe a system for interactively acquiring depth for an image-based representation consisting of a single input image. We use layers of images with depth to represent the scene. Unlike traditional 3D modeling and ...

Chen, Max, 1977-

2001-01-01

403

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

404

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

405

Digital Image Compression  

Microsoft Academic Search

Nondeterministic finite automata with states and transitions labeled by real-valued weights have turned out to be powerful\\u000a tools for the representation and compression of digital grayscale and color images. The addressing of pixels by input-sequences\\u000a is extended to cover multi-resolution images. Encoding algorithms for such weighted finite automata (WFA) exploit self-similarities\\u000a for efficient image compression, outperforming the well-known JPEG baseline

Jürgen Albert; Jarkko Kari

2009-01-01

406

An in situ approach to detect tree root ecology: linking ground-penetrating radar imaging to isotope-derived water acquisition zones.  

PubMed

Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite-granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of ?(18)O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil ?(18)O isotopic signature declined with depth, providing conditions for plant-soil ?(18)O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10-20 cm depth but broader under phyllite-granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground-penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic-dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree-based landscapes. PMID:23762519

Isaac, Marney E; Anglaaere, Luke C N

2013-05-01

407

An in situ approach to detect tree root ecology: linking ground-penetrating radar imaging to isotope-derived water acquisition zones  

PubMed Central

Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite–granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of ?18O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified