Digital Simulation Of Precise Sensor Degradations Including Non-Linearities And Shift Variance

NASA Astrophysics Data System (ADS)

Kornfeld, Gertrude H.

1987-09-01

Realistic atmospheric and Forward Looking Infrared Radiometer (FLIR) degradations were digitally simulated. Inputs to the routine are environmental observables and the FLIR specifications. It was possible to achieve realism in the thermal domain within acceptable computer time and random access memory (RAM) requirements because a shift variant recursive convolution algorithm that well describes thermal properties was invented and because each picture element (pixel) has radiative temperature, a materials parameter and range and altitude information. The computer generation steps start with the image synthesis of an undegraded scene. Atmospheric and sensor degradation follow. The final result is a realistic representation of an image seen on the display of a specific FLIR.

Genetically encoded calcium indicators for multi-color neural activity imaging and combination with optogenetics

PubMed Central

Akerboom, Jasper; Carreras Calderón, Nicole; Tian, Lin; Wabnig, Sebastian; Prigge, Matthias; Tolö, Johan; Gordus, Andrew; Orger, Michael B.; Severi, Kristen E.; Macklin, John J.; Patel, Ronak; Pulver, Stefan R.; Wardill, Trevor J.; Fischer, Elisabeth; Schüler, Christina; Chen, Tsai-Wen; Sarkisyan, Karen S.; Marvin, Jonathan S.; Bargmann, Cornelia I.; Kim, Douglas S.; Kügler, Sebastian; Lagnado, Leon; Hegemann, Peter; Gottschalk, Alexander; Schreiter, Eric R.; Looger, Loren L.

2013-01-01

Genetically encoded calcium indicators (GECIs) are powerful tools for systems neuroscience. Here we describe red, single-wavelength GECIs, “RCaMPs,” engineered from circular permutation of the thermostable red fluorescent protein mRuby. High-resolution crystal structures of mRuby, the red sensor RCaMP, and the recently published red GECI R-GECO1 give insight into the chromophore environments of the Ca2+-bound state of the sensors and the engineered protein domain interfaces of the different indicators. We characterized the biophysical properties and performance of RCaMP sensors in vitro and in vivo in Caenorhabditis elegans, Drosophila larvae, and larval zebrafish. Further, we demonstrate 2-color calcium imaging both within the same cell (registering mitochondrial and somatic [Ca2+]) and between two populations of cells: neurons and astrocytes. Finally, we perform integrated optogenetics experiments, wherein neural activation via channelrhodopsin-2 (ChR2) or a red-shifted variant, and activity imaging via RCaMP or GCaMP, are conducted simultaneously, with the ChR2/RCaMP pair providing independently addressable spectral channels. Using this paradigm, we measure calcium responses of naturalistic and ChR2-evoked muscle contractions in vivo in crawling C. elegans. We systematically compare the RCaMP sensors to R-GECO1, in terms of action potential-evoked fluorescence increases in neurons, photobleaching, and photoswitching. R-GECO1 displays higher Ca2+ affinity and larger dynamic range than RCaMP, but exhibits significant photoactivation with blue and green light, suggesting that integrated channelrhodopsin-based optogenetics using R-GECO1 may be subject to artifact. Finally, we create and test blue, cyan, and yellow variants engineered from GCaMP by rational design. This engineered set of chromatic variants facilitates new experiments in functional imaging and optogenetics. PMID:23459413

Information theoretic analysis of canny edge detection in visual communication

NASA Astrophysics Data System (ADS)

Jiang, Bo; Rahman, Zia-ur

2011-06-01

In general edge detection evaluation, the edge detectors are examined, analyzed, and compared either visually or with a metric for specific an application. This analysis is usually independent of the characteristics of the image-gathering, transmission and display processes that do impact the quality of the acquired image and thus, the resulting edge image. We propose a new information theoretic analysis of edge detection that unites the different components of the visual communication channel and assesses edge detection algorithms in an integrated manner based on Shannon's information theory. The edge detection algorithm here is considered to achieve high performance only if the information rate from the scene to the edge approaches the maximum possible. Thus, by setting initial conditions of the visual communication system as constant, different edge detection algorithms could be evaluated. This analysis is normally limited to linear shift-invariant filters so in order to examine the Canny edge operator in our proposed system, we need to estimate its "power spectral density" (PSD). Since the Canny operator is non-linear and shift variant, we perform the estimation for a set of different system environment conditions using simulations. In our paper we will first introduce the PSD of the Canny operator for a range of system parameters. Then, using the estimated PSD, we will assess the Canny operator using information theoretic analysis. The information-theoretic metric is also used to compare the performance of the Canny operator with other edge-detection operators. This also provides a simple tool for selecting appropriate edgedetection algorithms based on system parameters, and for adjusting their parameters to maximize information throughput.

Shift-variant linear system modeling for multispectral scanners

NASA Astrophysics Data System (ADS)

Amini, Abolfazl M.; Ioup, George E.; Ioup, Juliette W.

1995-07-01

Multispectral scanner data are affected both by the spatial impulse response of the sensor and the spectral response of each channel. To achieve a realistic representation for the output data for a given scene spectral input, both of these effects must be incorporated into a forward model. Each channel can have a different spatial response and each has its characteristic spectral response. A forward model is built which includes the shift invariant spatial broadening of the input for the channels and the shift variant spectral response across channels. The model is applied to the calibrated airborne multispectral scanner as well as the airborne terrestrial applications sensor developed at NASA Stennis Space Center.

Characterization of form variants of Xenorhabdus luminescens.

PubMed Central

Gerritsen, L J; de Raay, G; Smits, P H

1992-01-01

From Xenorhabdus luminescens XE-87.3 four variants were isolated. One, which produced a red pigment and antibiotics, was luminescent, and could take up dye from culture media, was considered the primary form (XE-red). A pink-pigmented variant (XE-pink) differed from the primary form only in pigmentation and uptake of dye. Of the two other variants, one produced a yellow pigment and fewer antibiotics (XE-yellow), while the other did not produce a pigment or antibiotics (XE-white). Both were less luminescent, did not take up dye, and had small cell and colony sizes. These two variants were very unstable and shifted to the primary form after 3 to 5 days. It was not possible to separate the primary form and the white variant completely; subcultures of one colony always contained a few colonies of the other variant. The white variant was also found in several other X. luminescens strains. DNA fingerprints showed that all four variants are genetically identical and are therefore derivatives of the same parent. Protein patterns revealed a few differences among the four variants. None of the variants could be considered the secondary form. The pathogenicity of the variants decreased in the following order: XE-red, XE-pink, XE-yellow, and XE-white. The mechanism and function of this variability are discussed. Images PMID:1622273

Theoretical foundations of spatially-variant mathematical morphology part ii: gray-level images.

PubMed

Bouaynaya, Nidhal; Schonfeld, Dan

2008-05-01

In this paper, we develop a spatially-variant (SV) mathematical morphology theory for gray-level signals and images in the Euclidean space. The proposed theory preserves the geometrical concept of the structuring function, which provides the foundation of classical morphology and is essential in signal and image processing applications. We define the basic SV gray-level morphological operators (i.e., SV gray-level erosion, dilation, opening, and closing) and investigate their properties. We demonstrate the ubiquity of SV gray-level morphological systems by deriving a kernel representation for a large class of systems, called V-systems, in terms of the basic SV graylevel morphological operators. A V-system is defined to be a gray-level operator, which is invariant under gray-level (vertical) translations. Particular attention is focused on the class of SV flat gray-level operators. The kernel representation for increasing V-systems is a generalization of Maragos' kernel representation for increasing and translation-invariant function-processing systems. A representation of V-systems in terms of their kernel elements is established for increasing and upper-semi-continuous V-systems. This representation unifies a large class of spatially-variant linear and non-linear systems under the same mathematical framework. Finally, simulation results show the potential power of the general theory of gray-level spatially-variant mathematical morphology in several image analysis and computer vision applications.

Molecular Mechanism of Wide Photoabsorption Spectral Shifts of Color Variants of Human Cellular Retinol Binding Protein II.

PubMed

Cheng, Cheng; Kamiya, Motoshi; Uchida, Yoshihiro; Hayashi, Shigehiko

2015-10-21

Color variants of human cellular retinol binding protein II (hCRBPII) created by protein engineering were recently shown to exhibit anomalously wide photoabsorption spectral shifts over ∼200 nm across the visible region. The remarkable phenomenon provides a unique opportunity to gain insight into the molecular basis of the color tuning of retinal binding proteins for understanding of color vision as well as for engineering of novel color variants of retinal binding photoreceptor proteins employed in optogenetics. Here, we report a theoretical investigation of the molecular mechanism underlying the anomalously wide spectral shifts of the color variants of hCRBPII. Computational modeling of the color variants with hybrid molecular simulations of free energy geometry optimization succeeded in reproducing the experimentally observed wide spectral shifts, and revealed that protein flexibility, through which the active site structure of the protein and bound water molecules is altered by remote mutations, plays a significant role in inducing the large spectral shifts.

Inner-volume echo volumar imaging (IVEVI) for robust fetal brain imaging.

PubMed

Nunes, Rita G; Ferrazzi, Giulio; Price, Anthony N; Hutter, Jana; Gaspar, Andreia S; Rutherford, Mary A; Hajnal, Joseph V

2018-07-01

Fetal functional MRI studies using conventional 2-dimensional single-shot echo-planar imaging sequences may require discarding a large data fraction as a result of fetal and maternal motion. Increasing the temporal resolution using echo volumar imaging (EVI) could provide an effective alternative strategy. Echo volumar imaging was combined with inner volume (IV) imaging (IVEVI) to locally excite the fetal brain and acquire full 3-dimensional images, fast enough to freeze most fetal head motion. IVEVI was implemented by modifying a standard multi-echo echo-planar imaging sequence. A spin echo with orthogonal excitation and refocusing ensured localized excitation. To introduce T2* weighting and to save time, the k-space center was shifted relative to the spin echo. Both single and multi-shot variants were tested. Acoustic noise was controlled by adjusting the amplitude and switching frequency of the readout gradient. Image-based shimming was used to minimize B 0 inhomogeneities within the fetal brain. The sequence was first validated in an adult. Eight fetuses were scanned using single-shot IVEVI at a 3.5 × 3.5 × 5.0 mm 3 resolution with a readout duration of 383 ms. Multishot IVEVI showed reduced geometric distortions along the second phase-encode direction. Fetal EVI remains challenging. Although effective echo times comparable to the T2* values of fetal cortical gray matter at 3 T could be achieved, controlling acoustic noise required longer readouts, leading to substantial distortions in single-shot images. Although multishot variants enabled us to reduce susceptibility-induced geometric distortions, sensitivity to motion was increased. Future studies should therefore focus on improvements to multishot variants. Magn Reson Med 80:279-285, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Low-dose cone-beam CT via raw counts domain low-signal correction schemes: Performance assessment and task-based parameter optimization (Part II. Task-based parameter optimization).

PubMed

Gomez-Cardona, Daniel; Hayes, John W; Zhang, Ran; Li, Ke; Cruz-Bastida, Juan Pablo; Chen, Guang-Hong

2018-05-01

Different low-signal correction (LSC) methods have been shown to efficiently reduce noise streaks and noise level in CT to provide acceptable images at low-radiation dose levels. These methods usually result in CT images with highly shift-variant and anisotropic spatial resolution and noise, which makes the parameter optimization process highly nontrivial. The purpose of this work was to develop a local task-based parameter optimization framework for LSC methods. Two well-known LSC methods, the adaptive trimmed mean (ATM) filter and the anisotropic diffusion (AD) filter, were used as examples to demonstrate how to use the task-based framework to optimize filter parameter selection. Two parameters, denoted by the set P, for each LSC method were included in the optimization problem. For the ATM filter, these parameters are the low- and high-signal threshold levels p l and p h ; for the AD filter, the parameters are the exponents δ and γ in the brightness gradient function. The detectability index d' under the non-prewhitening (NPW) mathematical observer model was selected as the metric for parameter optimization. The optimization problem was formulated as an unconstrained optimization problem that consisted of maximizing an objective function d'(P), where i and j correspond to the i-th imaging task and j-th spatial location, respectively. Since there is no explicit mathematical function to describe the dependence of d' on the set of parameters P for each LSC method, the optimization problem was solved via an experimentally measured d' map over a densely sampled parameter space. In this work, three high-contrast-high-frequency discrimination imaging tasks were defined to explore the parameter space of each of the LSC methods: a vertical bar pattern (task I), a horizontal bar pattern (task II), and a multidirectional feature (task III). Two spatial locations were considered for the analysis, a posterior region-of-interest (ROI) located within the noise streaks region and an anterior ROI, located further from the noise streaks region. Optimal results derived from the task-based detectability index metric were compared to other operating points in the parameter space with different noise and spatial resolution trade-offs. The optimal operating points determined through the d' metric depended on the interplay between the major spatial frequency components of each imaging task and the highly shift-variant and anisotropic noise and spatial resolution properties associated with each operating point in the LSC parameter space. This interplay influenced imaging performance the most when the major spatial frequency component of a given imaging task coincided with the direction of spatial resolution loss or with the dominant noise spatial frequency component; this was the case of imaging task II. The performance of imaging tasks I and III was influenced by this interplay in a smaller scale than imaging task II, since the major frequency component of task I was perpendicular to imaging task II, and because imaging task III did not have strong directional dependence. For both LSC methods, there was a strong dependence of the overall d' magnitude and shape of the contours on the spatial location within the phantom, particularly for imaging tasks II and III. The d' value obtained at the optimal operating point for each spatial location and imaging task was similar when comparing the LSC methods studied in this work. A local task-based detectability framework to optimize the selection of parameters for LSC methods was developed. The framework takes into account the potential shift-variant and anisotropic spatial resolution and noise properties to maximize the imaging performance of the CT system. Optimal parameters for a given LSC method depend strongly on the spatial location within the image object. © 2018 American Association of Physicists in Medicine.

Engineering 'Golden' Fluorescence by Selective Pressure Incorporation of Non-canonical Amino Acids and Protein Analysis by Mass Spectrometry and Fluorescence.

PubMed

Baumann, Tobias; Schmitt, Franz-Josef; Pelzer, Almut; Spiering, Vivian Jeanette; Freiherr von Sass, Georg Johannes; Friedrich, Thomas; Budisa, Nediljko

2018-04-27

Fluorescent proteins are fundamental tools for the life sciences, in particular for fluorescence microscopy of living cells. While wild-type and engineered variants of the green fluorescent protein from Aequorea victoria (avGFP) as well as homologs from other species already cover large parts of the optical spectrum, a spectral gap remains in the near-infrared region, for which avGFP-based fluorophores are not available. Red-shifted fluorescent protein (FP) variants would substantially expand the toolkit for spectral unmixing of multiple molecular species, but the naturally occurring red-shifted FPs derived from corals or sea anemones have lower fluorescence quantum yield and inferior photo-stability compared to the avGFP variants. Further manipulation and possible expansion of the chromophore's conjugated system towards the far-red spectral region is also limited by the repertoire of 20 canonical amino acids prescribed by the genetic code. To overcome these limitations, synthetic biology can achieve further spectral red-shifting via insertion of non-canonical amino acids into the chromophore triad. We describe the application of SPI to engineer avGFP variants with novel spectral properties. Protein expression is performed in a tryptophan-auxotrophic E. coli strain and by supplementing growth media with suitable indole precursors. Inside the cells, these precursors are converted to the corresponding tryptophan analogs and incorporated into proteins by the ribosomal machinery in response to UGG codons. The replacement of Trp-66 in the enhanced "cyan" variant of avGFP (ECFP) by an electron-donating 4-aminotryptophan results in GdFP featuring a 108 nm Stokes shift and a strongly red-shifted emission maximum (574 nm), while being thermodynamically more stable than its predecessor ECFP. Residue-specific incorporation of the non-canonical amino acid is analyzed by mass spectrometry. The spectroscopic properties of GdFP are characterized by time-resolved fluorescence spectroscopy as one of the valuable applications of genetically encoded FPs in life sciences.

Room temperature spectrally resolved single-molecule spectroscopy reveals new spectral forms and photophysical versatility of aequorea green fluorescent protein variants.

PubMed

Blum, Christian; Meixner, Alfred J; Subramaniam, Vinod

2004-12-01

It is known from ensemble spectroscopy at cryogenic temperatures that variants of the Aequorea green fluorescent protein (GFP) occur in interconvertible spectroscopically distinct forms which are obscured in ensemble room temperature spectroscopy. By analyzing the fluorescence of the GFP variants EYFP and EGFP by spectrally resolved single-molecule spectroscopy we were able to observe spectroscopically different forms of the proteins and to dynamically monitor transitions between these forms at room temperature. In addition to the predominant EYFP B-form we have observed the blue-shifted I-form thus far only seen at cryogenic temperatures and have followed transitions between these forms. Further we have identified for EYFP and for EGFP three more, so far unknown, forms with red-shifted fluorescence. Transitions between the predominant forms and the red-shifted forms show a dark time which indicates the existence of a nonfluorescent intermediate. The spectral position of the newly-identified red-shifted forms and their formation via a nonfluorescent intermediate hint that these states may account for the possible photoactivation observed in bulk experiments. The comparison of the single-protein spectra of the red-shifted EYFP and EGFP forms with single-molecule fluorescence spectra of DsRed suggest that these new forms possibly originate from an extended chromophoric pi-system analogous to the DsRed chromophore.

In-line phase shift tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammonds, Jeffrey C.; Price, Ronald R.; Pickens, David R.

2013-08-15

Purpose: The purpose of this work is to (1) demonstrate laboratory measurements of phase shift images derived from in-line phase-contrast radiographs using the attenuation-partition based algorithm (APBA) of Yan et al.[Opt. Express 18(15), 16074–16089 (2010)], (2) verify that the APBA reconstructed images obey the linearity principle, and (3) reconstruct tomosynthesis phase shift images from a collection of angularly sampled planar phase shift images.Methods: An unmodified, commercially available cabinet x-ray system (Faxitron LX-60) was used in this experiment. This system contains a tungsten anode x-ray tube with a nominal focal spot size of 10 μm. The digital detector uses CsI/CMOS withmore » a pixel size of 50 × 50 μm. The phantoms used consisted of one acrylic plate, two polystyrene plates, and a habanero pepper. Tomosynthesis images were reconstructed from 51 images acquired over a ±25° arc. All phase shift images were reconstructed using the APBA.Results: Image contrast derived from the planar phase shift image of an acrylic plate of uniform thickness exceeded the contrast of the traditional attenuation image by an approximate factor of two. Comparison of the planar phase shift images from a single, uniform thickness polystyrene plate with two polystyrene plates demonstrated an approximate linearity of the estimated phase shift with plate thickness (−1600 rad vs −2970 rad). Tomographic phase shift images of the habanero pepper exhibited acceptable spatial resolution and contrast comparable to the corresponding attenuation image.Conclusions: This work demonstrated the feasibility of laboratory-based phase shift tomosynthesis and suggests that phase shift imaging could potentially provide a new imaging biomarker. Further investigation will be needed to determine if phase shift contrast will be able to provide new tissue contrast information or improved clinical performance.« less

Rational design of a monomeric and photostable far-red fluorescent protein for fluorescence imaging in vivo.

PubMed

Yu, Dan; Dong, Zhiqiang; Gustafson, William Clay; Ruiz-González, Rubén; Signor, Luca; Marzocca, Fanny; Borel, Franck; Klassen, Matthew P; Makhijani, Kalpana; Royant, Antoine; Jan, Yuh-Nung; Weiss, William A; Guo, Su; Shu, Xiaokun

2016-02-01

Fluorescent proteins (FPs) are powerful tools for cell and molecular biology. Here based on structural analysis, a blue-shifted mutant of a recently engineered monomeric infrared fluorescent protein (mIFP) has been rationally designed. This variant, named iBlueberry, bears a single mutation that shifts both excitation and emission spectra by approximately 40 nm. Furthermore, iBlueberry is four times more photostable than mIFP, rendering it more advantageous for imaging protein dynamics. By tagging iBlueberry to centrin, it has been demonstrated that the fusion protein labels the centrosome in the developing zebrafish embryo. Together with GFP-labeled nucleus and tdTomato-labeled plasma membrane, time-lapse imaging to visualize the dynamics of centrosomes in radial glia neural progenitors in the intact zebrafish brain has been demonstrated. It is further shown that iBlueberry can be used together with mIFP in two-color protein labeling in living cells and in two-color tumor labeling in mice. © 2015 The Protein Society.

MAI-free performance of PMU-OFDM transceiver in time-variant environment

NASA Astrophysics Data System (ADS)

Tadjpour, Layla; Tsai, Shang-Ho; Kuo, C.-C. J.

2005-06-01

An approximately multi-user OFDM transceiver was introduced to reduce the multi-access interference (MAI ) due to the carrier frequency offset (CFO) to a negligible amount via precoding by Tsai, Lin and Kuo. In this work, we investigate the performance of this precoded multi-user (PMU) OFDM system in a time-variant channel environment. We analyze and compare the MAI effect caused by time-variant channels in the PMU-OFDM and the OFDMA systems. Generally speaking, the MAI effect consists of two parts. The first part is due to the loss of orthogonality among subchannels for all users while the second part is due to the CFO effect caused by the Doppler shift. Simulation results show that, although OFDMA outperforms the PMU-OFDM transceiver in a fast time-variant environment without CFO, PMU-OFDM outperforms OFDMA in a slow time-variant channel via the use of M/2 symmetric or anti-symmetric codewords of M Hadamard-Walsh codes.

Canary: an atomic pipeline for clinical amplicon assays.

PubMed

Doig, Kenneth D; Ellul, Jason; Fellowes, Andrew; Thompson, Ella R; Ryland, Georgina; Blombery, Piers; Papenfuss, Anthony T; Fox, Stephen B

2017-12-15

High throughput sequencing requires bioinformatics pipelines to process large volumes of data into meaningful variants that can be translated into a clinical report. These pipelines often suffer from a number of shortcomings: they lack robustness and have many components written in multiple languages, each with a variety of resource requirements. Pipeline components must be linked together with a workflow system to achieve the processing of FASTQ files through to a VCF file of variants. Crafting these pipelines requires considerable bioinformatics and IT skills beyond the reach of many clinical laboratories. Here we present Canary, a single program that can be run on a laptop, which takes FASTQ files from amplicon assays through to an annotated VCF file ready for clinical analysis. Canary can be installed and run with a single command using Docker containerization or run as a single JAR file on a wide range of platforms. Although it is a single utility, Canary performs all the functions present in more complex and unwieldy pipelines. All variants identified by Canary are 3' shifted and represented in their most parsimonious form to provide a consistent nomenclature, irrespective of sequencing variation. Further, proximate in-phase variants are represented as a single HGVS 'delins' variant. This allows for correct nomenclature and consequences to be ascribed to complex multi-nucleotide polymorphisms (MNPs), which are otherwise difficult to represent and interpret. Variants can also be annotated with hundreds of attributes sourced from MyVariant.info to give up to date details on pathogenicity, population statistics and in-silico predictors. Canary has been used at the Peter MacCallum Cancer Centre in Melbourne for the last 2 years for the processing of clinical sequencing data. By encapsulating clinical features in a single, easily installed executable, Canary makes sequencing more accessible to all pathology laboratories. Canary is available for download as source or a Docker image at https://github.com/PapenfussLab/Canary under a GPL-3.0 License.

Photoswitchable red fluorescent protein with a large Stokes shift

PubMed Central

Piatkevich, Kiryl D.; English, Brian P.; Malashkevich, Vladimir N.; Xiao, Hui; Almo, Steven C.; Singer, Robert H.; Verkhusha, Vladislav V.

2014-01-01

SUMMARY Subclass of fluorescent proteins, large Stokes shift fluorescent proteins, is characterized by their increased spread between the excitation and emission maxima. Here we report a photoswitchable variant of a red fluorescent protein with a large Stokes shift, PSLSSmKate, which initially exhibits excitation/emission at 445/622 nm, but irradiation with violet light photoswitches PSLSSmKate into a common red form with excitation/emission at 573/621 nm. We characterize spectral, photophysical and biochemical properties of PSLSSmKate in vitro and in mammalian cells, and determine its crystal structure in the large Stokes shift form. Mass-spectrometry, mutagenesis and spectroscopic analysis of PSLSSmKate allow us to propose molecular mechanisms for the large Stokes shift, pH dependence and light-induced chromophore transformation. We demonstrate applicability of PSLSSmKate to superresolution PALM microscopy and protein dynamics in live cells. Given its promising properties, we expect that PSLSSmKate-like phenotype will be further used for photoactivatable imaging and tracking multiple populations of intracellular objects. PMID:25242289

Overcoming turbulence-induced space-variant blur by using phase-diverse speckle.

PubMed

Thelen, Brian J; Paxman, Richard G; Carrara, David A; Seldin, John H

2009-01-01

Space-variant blur occurs when imaging through volume turbulence over sufficiently large fields of view. Space-variant effects are particularly severe in horizontal-path imaging, slant-path (air-to-ground or ground-to-air) geometries, and ground-based imaging of low-elevation satellites or astronomical objects. In these geometries, the isoplanatic angle can be comparable to or even smaller than the diffraction-limited resolution angle. We report on a postdetection correction method that seeks to correct for the effects of space-variant aberrations, with the goal of reconstructing near-diffraction-limited imagery. Our approach has been to generalize the method of phase-diverse speckle (PDS) by using a physically motivated distributed-phase-screen model. Simulation results are presented that demonstrate the reconstruction of near-diffraction-limited imagery under both matched and mismatched model assumptions. In addition, we present evidence that PDS could be used as a beaconless wavefront sensor in a multiconjugate adaptive optics system when imaging extended scenes.

Image reconstructions from super-sampled data sets with resolution modeling in PET imaging.

PubMed

Li, Yusheng; Matej, Samuel; Metzler, Scott D

2014-12-01

Spatial resolution in positron emission tomography (PET) is still a limiting factor in many imaging applications. To improve the spatial resolution for an existing scanner with fixed crystal sizes, mechanical movements such as scanner wobbling and object shifting have been considered for PET systems. Multiple acquisitions from different positions can provide complementary information and increased spatial sampling. The objective of this paper is to explore an efficient and useful reconstruction framework to reconstruct super-resolution images from super-sampled low-resolution data sets. The authors introduce a super-sampling data acquisition model based on the physical processes with tomographic, downsampling, and shifting matrices as its building blocks. Based on the model, we extend the MLEM and Landweber algorithms to reconstruct images from super-sampled data sets. The authors also derive a backprojection-filtration-like (BPF-like) method for the super-sampling reconstruction. Furthermore, they explore variant methods for super-sampling reconstructions: the separate super-sampling resolution-modeling reconstruction and the reconstruction without downsampling to further improve image quality at the cost of more computation. The authors use simulated reconstruction of a resolution phantom to evaluate the three types of algorithms with different super-samplings at different count levels. Contrast recovery coefficient (CRC) versus background variability, as an image-quality metric, is calculated at each iteration for all reconstructions. The authors observe that all three algorithms can significantly and consistently achieve increased CRCs at fixed background variability and reduce background artifacts with super-sampled data sets at the same count levels. For the same super-sampled data sets, the MLEM method achieves better image quality than the Landweber method, which in turn achieves better image quality than the BPF-like method. The authors also demonstrate that the reconstructions from super-sampled data sets using a fine system matrix yield improved image quality compared to the reconstructions using a coarse system matrix. Super-sampling reconstructions with different count levels showed that the more spatial-resolution improvement can be obtained with higher count at a larger iteration number. The authors developed a super-sampling reconstruction framework that can reconstruct super-resolution images using the super-sampling data sets simultaneously with known acquisition motion. The super-sampling PET acquisition using the proposed algorithms provides an effective and economic way to improve image quality for PET imaging, which has an important implication in preclinical and clinical region-of-interest PET imaging applications.

Image Processing for Cameras with Fiber Bundle Image Relay

DTIC Science & Technology

length. Optical fiber bundles have been used to couple between this focal surface and planar image sensors . However, such fiber-coupled imaging systems...coupled to six discrete CMOS focal planes. We characterize the locally space-variant system impulse response at various stages: monocentric lens image...vignetting, and stitch together the image data from discrete sensors into a single panorama. We compare processed images from the prototype to those taken with

Development of measurement system for gauge block interferometer

NASA Astrophysics Data System (ADS)

Chomkokard, S.; Jinuntuya, N.; Wongkokua, W.

2017-09-01

We developed a measurement system for collecting and analyzing the fringe pattern images from a gauge block interferometer. The system was based on Raspberry Pi which is an open source system with python programming and opencv image manipulation library. The images were recorded by the Raspberry Pi camera with five-megapixel capacity. The noise of images was suppressed for the best result in analyses. The low noise images were processed to find the edge of fringe patterns using the contour technique for the phase shift analyses. We tested our system with the phase shift patterns between a gauge block and a reference plate. The phase shift patterns were measured by a Twyman-Green type of interferometer using the He-Ne laser with the temperature controlled at 20.0 °C. The results of the measurement will be presented and discussed.

Multispectral multisensor image fusion using wavelet transforms

USGS Publications Warehouse

Lemeshewsky, George P.

1999-01-01

Fusion techniques can be applied to multispectral and higher spatial resolution panchromatic images to create a composite image that is easier to interpret than the individual images. Wavelet transform-based multisensor, multiresolution fusion (a type of band sharpening) was applied to Landsat thematic mapper (TM) multispectral and coregistered higher resolution SPOT panchromatic images. The objective was to obtain increased spatial resolution, false color composite products to support the interpretation of land cover types wherein the spectral characteristics of the imagery are preserved to provide the spectral clues needed for interpretation. Since the fusion process should not introduce artifacts, a shift invariant implementation of the discrete wavelet transform (SIDWT) was used. These results were compared with those using the shift variant, discrete wavelet transform (DWT). Overall, the process includes a hue, saturation, and value color space transform to minimize color changes, and a reported point-wise maximum selection rule to combine transform coefficients. The performance of fusion based on the SIDWT and DWT was evaluated with a simulated TM 30-m spatial resolution test image and a higher resolution reference. Simulated imagery was made by blurring higher resolution color-infrared photography with the TM sensors' point spread function. The SIDWT based technique produced imagery with fewer artifacts and lower error between fused images and the full resolution reference. Image examples with TM and SPOT 10-m panchromatic illustrate the reduction in artifacts due to the SIDWT based fusion.

A spatially-variant deconvolution method based on total variation for optical coherence tomography images

NASA Astrophysics Data System (ADS)

Almasganj, Mohammad; Adabi, Saba; Fatemizadeh, Emad; Xu, Qiuyun; Sadeghi, Hamid; Daveluy, Steven; Nasiriavanaki, Mohammadreza

2017-03-01

Optical Coherence Tomography (OCT) has a great potential to elicit clinically useful information from tissues due to its high axial and transversal resolution. In practice, an OCT setup cannot reach to its theoretical resolution due to imperfections of its components, which make its images blurry. The blurriness is different alongside regions of image; thus, they cannot be modeled by a unique point spread function (PSF). In this paper, we investigate the use of solid phantoms to estimate the PSF of each sub-region of imaging system. We then utilize Lucy-Richardson, Hybr and total variation (TV) based iterative deconvolution methods for mitigating occurred spatially variant blurriness. It is shown that the TV based method will suppress the so-called speckle noise in OCT images better than the two other approaches. The performance of proposed algorithm is tested on various samples, including several skin tissues besides the test image blurred with synthetic PSF-map, demonstrating qualitatively and quantitatively the advantage of TV based deconvolution method using spatially-variant PSF for enhancing image quality.

Application of field dependent polynomial model

NASA Astrophysics Data System (ADS)

Janout, Petr; Páta, Petr; Skala, Petr; Fliegel, Karel; Vítek, Stanislav; Bednář, Jan

2016-09-01

Extremely wide-field imaging systems have many advantages regarding large display scenes whether for use in microscopy, all sky cameras, or in security technologies. The Large viewing angle is paid by the amount of aberrations, which are included with these imaging systems. Modeling wavefront aberrations using the Zernike polynomials is known a longer time and is widely used. Our method does not model system aberrations in a way of modeling wavefront, but directly modeling of aberration Point Spread Function of used imaging system. This is a very complicated task, and with conventional methods, it was difficult to achieve the desired accuracy. Our optimization techniques of searching coefficients space-variant Zernike polynomials can be described as a comprehensive model for ultra-wide-field imaging systems. The advantage of this model is that the model describes the whole space-variant system, unlike the majority models which are partly invariant systems. The issue that this model is the attempt to equalize the size of the modeled Point Spread Function, which is comparable to the pixel size. Issues associated with sampling, pixel size, pixel sensitivity profile must be taken into account in the design. The model was verified in a series of laboratory test patterns, test images of laboratory light sources and consequently on real images obtained by an extremely wide-field imaging system WILLIAM. Results of modeling of this system are listed in this article.

Image-based Modeling of PSF Deformation with Application to Limited Angle PET Data

PubMed Central

Matej, Samuel; Li, Yusheng; Panetta, Joseph; Karp, Joel S.; Surti, Suleman

2016-01-01

The point-spread-functions (PSFs) of reconstructed images can be deformed due to detector effects such as resolution blurring and parallax error, data acquisition geometry such as insufficient sampling or limited angular coverage in dual-panel PET systems, or reconstruction imperfections/simplifications. PSF deformation decreases quantitative accuracy and its spatial variation lowers consistency of lesion uptake measurement across the imaging field-of-view (FOV). This can be a significant problem with dual panel PET systems even when using TOF data and image reconstruction models of the detector and data acquisition process. To correct for the spatially variant reconstructed PSF distortions we propose to use an image-based resolution model (IRM) that includes such image PSF deformation effects. Originally the IRM was mostly used for approximating data resolution effects of standard PET systems with full angular coverage in a computationally efficient way, but recently it was also used to mitigate effects of simplified geometric projectors. Our work goes beyond this by including into the IRM reconstruction imperfections caused by combination of the limited angle, parallax errors, and any other (residual) deformation effects and testing it for challenging dual panel data with strongly asymmetric and variable PSF deformations. We applied and tested these concepts using simulated data based on our design for a dedicated breast imaging geometry (B-PET) consisting of dual-panel, time-of-flight (TOF) detectors. We compared two image-based resolution models; i) a simple spatially invariant approximation to PSF deformation, which captures only the general PSF shape through an elongated 3D Gaussian function, and ii) a spatially variant model using a Gaussian mixture model (GMM) to more accurately capture the asymmetric PSF shape in images reconstructed from data acquired with the B-PET scanner geometry. Results demonstrate that while both IRMs decrease the overall uptake bias in the reconstructed image, the second one with the spatially variant and accurate PSF shape model is also able to ameliorate the spatially variant deformation effects to provide consistent uptake results independent of the lesion location within the FOV. PMID:27812222

Along-track calibration of SWIR push-broom hyperspectral imaging system

NASA Astrophysics Data System (ADS)

Jemec, Jurij; Pernuš, Franjo; Likar, Boštjan; Bürmen, Miran

2016-05-01

Push-broom hyperspectral imaging systems are increasingly used for various medical, agricultural and military purposes. The acquired images contain spectral information in every pixel of the imaged scene collecting additional information about the imaged scene compared to the classical RGB color imaging. Due to the misalignment and imperfections in the optical components comprising the push-broom hyperspectral imaging system, variable spectral and spatial misalignments and blur are present in the acquired images. To capture these distortions, a spatially and spectrally variant response function must be identified at each spatial and spectral position. In this study, we propose a procedure to characterize the variant response function of Short-Wavelength Infrared (SWIR) push-broom hyperspectral imaging systems in the across-track and along-track direction and remove its effect from the acquired images. A custom laser-machined spatial calibration targets are used for the characterization. The spatial and spectral variability of the response function in the across-track and along-track direction is modeled by a parametrized basis function. Finally, the characterization results are used to restore the distorted hyperspectral images in the across-track and along-track direction by a Richardson-Lucy deconvolution-based algorithm. The proposed calibration method in the across-track and along-track direction is thoroughly evaluated on images of targets with well-defined geometric properties. The results suggest that the proposed procedure is well suited for fast and accurate spatial calibration of push-broom hyperspectral imaging systems.

SU-F-J-47: Inherent Uncertainty in the Positional Shifts Determined by a Volumetric Cone Beam Imaging System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giri, U; Ganesh, T; Saini, V

2016-06-15

Purpose: To quantify inherent uncertainty associated with a volumetric imaging system in its determination of positional shifts. Methods: The study was performed on an Elekta Axesse™ linac’s XVI cone beam computed tomography (CBCT) system. A CT image data set of a Penta- Guide phantom was used as reference image by placing isocenter at the center of the phantom.The phantom was placed arbitrarily on the couch close to isocenter and CBCT images were obtained. The CBCT dataset was matched with the reference image using XVI software and the shifts were determined in 6-dimensions. Without moving the phantom, this process was repeatedmore » 20 times consecutively within 30 minutes on a single day. Mean shifts and their standard deviations in all 6-dimensions were determined for all the 20 instances of imaging. For any given day, the first set of shifts obtained was kept as reference and the deviations of the subsequent 19 sets from the reference set were scored. Mean differences and their standard deviations were determined. In this way, data were obtained for 30 consecutive working days. Results: Tabulating the mean deviations and their standard deviations observed on each day for the 30 measurement days, systematic and random errors in the determination of shifts by XVI software were calculated. The systematic errors were found to be 0.03, 0.04 and 0.03 mm while random errors were 0.05, 0.06 and 0.06 mm in lateral, craniocaudal and anterio-posterior directions respectively. For rotational shifts, the systematic errors were 0.02°, 0.03° and 0.03° and random errors were 0.06°, 0.05° and 0.05° in pitch, roll and yaw directions respectively. Conclusion: The inherent uncertainties in every image guidance system should be assessed and baseline values established at the time of its commissioning. These shall be periodically tested as part of the QA protocol.« less

A linear shift-invariant image preprocessing technique for multispectral scanner systems

NASA Technical Reports Server (NTRS)

Mcgillem, C. D.; Riemer, T. E.

1973-01-01

A linear shift-invariant image preprocessing technique is examined which requires no specific knowledge of any parameter of the original image and which is sufficiently general to allow the effective radius of the composite imaging system to be arbitrarily shaped and reduced, subject primarily to the noise power constraint. In addition, the size of the point-spread function of the preprocessing filter can be arbitrarily controlled, thus minimizing truncation errors.

Study of nanometer-level precise phase-shift system used in electronic speckle shearography and phase-shift pattern interferometry

NASA Astrophysics Data System (ADS)

Jing, Chao; Liu, Zhongling; Zhou, Ge; Zhang, Yimo

2011-11-01

The nanometer-level precise phase-shift system is designed to realize the phase-shift interferometry in electronic speckle shearography pattern interferometry. The PZT is used as driving component of phase-shift system and translation component of flexure hinge is developed to realize micro displacement of non-friction and non-clearance. Closed-loop control system is designed for high-precision micro displacement, in which embedded digital control system is developed for completing control algorithm and capacitive sensor is used as feedback part for measuring micro displacement in real time. Dynamic model and control model of the nanometer-level precise phase-shift system is analyzed, and high-precision micro displacement is realized with digital PID control algorithm on this basis. It is proved with experiments that the location precision of the precise phase-shift system to step signal of displacement is less than 2nm and the location precision to continuous signal of displacement is less than 5nm, which is satisfied with the request of the electronic speckle shearography and phase-shift pattern interferometry. The stripe images of four-step phase-shift interferometry and the final phase distributed image correlated with distortion of objects are listed in this paper to prove the validity of nanometer-level precise phase-shift system.

Single scan parameterization of space-variant point spread functions in image space via a printed array: the impact for two PET/CT scanners.

PubMed

Kotasidis, F A; Matthews, J C; Angelis, G I; Noonan, P J; Jackson, A; Price, P; Lionheart, W R; Reader, A J

2011-05-21

Incorporation of a resolution model during statistical image reconstruction often produces images of improved resolution and signal-to-noise ratio. A novel and practical methodology to rapidly and accurately determine the overall emission and detection blurring component of the system matrix using a printed point source array within a custom-made Perspex phantom is presented. The array was scanned at different positions and orientations within the field of view (FOV) to examine the feasibility of extrapolating the measured point source blurring to other locations in the FOV and the robustness of measurements from a single point source array scan. We measured the spatially-variant image-based blurring on two PET/CT scanners, the B-Hi-Rez and the TruePoint TrueV. These measured spatially-variant kernels and the spatially-invariant kernel at the FOV centre were then incorporated within an ordinary Poisson ordered subset expectation maximization (OP-OSEM) algorithm and compared to the manufacturer's implementation using projection space resolution modelling (RM). Comparisons were based on a point source array, the NEMA IEC image quality phantom, the Cologne resolution phantom and two clinical studies (carbon-11 labelled anti-sense oligonucleotide [(11)C]-ASO and fluorine-18 labelled fluoro-l-thymidine [(18)F]-FLT). Robust and accurate measurements of spatially-variant image blurring were successfully obtained from a single scan. Spatially-variant resolution modelling resulted in notable resolution improvements away from the centre of the FOV. Comparison between spatially-variant image-space methods and the projection-space approach (the first such report, using a range of studies) demonstrated very similar performance with our image-based implementation producing slightly better contrast recovery (CR) for the same level of image roughness (IR). These results demonstrate that image-based resolution modelling within reconstruction is a valid alternative to projection-based modelling, and that, when using the proposed practical methodology, the necessary resolution measurements can be obtained from a single scan. This approach avoids the relatively time-consuming and involved procedures previously proposed in the literature.

Synchronous Bioimaging of Intracellular pH and Chloride Based on LSS Fluorescent Protein.

PubMed

Paredes, Jose M; Idilli, Aurora I; Mariotti, Letizia; Losi, Gabriele; Arslanbaeva, Lyaysan R; Sato, Sebastian Sulis; Artoni, Pietro; Szczurkowska, Joanna; Cancedda, Laura; Ratto, Gian Michele; Carmignoto, Giorgio; Arosio, Daniele

2016-06-17

Ion homeostasis regulates critical physiological processes in the living cell. Intracellular chloride concentration not only contributes in setting the membrane potential of quiescent cells but it also plays a role in modulating the dynamic voltage changes during network activity. Dynamic chloride imaging demands new tools, allowing faster acquisition rates and correct accounting of concomitant pH changes. Joining a long-Stokes-shift red-fluorescent protein to a GFP variant with high sensitivity to pH and chloride, we obtained LSSmClopHensor, a genetically encoded fluorescent biosensor optimized for the simultaneous chloride and pH imaging and requiring only two excitation wavelengths (458 and 488 nm). LSSmClopHensor allowed us to monitor the dynamic changes of intracellular pH and chloride concentration during seizure like discharges in neocortical brain slices. Only cells with tightly controlled resting potential revealed a narrow distribution of chloride concentration peaking at about 5 and 8 mM, in neocortical neurons and SK-N-SH cells, respectively. We thus showed that LSSmClopHensor represents a new versatile tool for studying the dynamics of chloride and proton concentration in living systems.

Emission shaping in fluorescent proteins: role of electrostatics and π-stacking.

PubMed

Park, Jae Woo; Rhee, Young Min

2016-02-07

For many decades, simulating the excited state properties of complex systems has been an intriguing but daunting task due to its high computational cost. Here, we apply molecular dynamics based techniques with interpolated potential energy surfaces toward calculating fluorescence spectra of the green fluorescent protein (GFP) and its variants in a statistically meaningful manner. With the GFP, we show that the diverse electrostatic tuning can shape the emission features in many different ways. By computationally modulating the electrostatic interactions between the chromophore phenoxy oxygen and its nearby residues, we demonstrate that we indeed can shift the emission to the blue or to the red side in a predictable manner. We rationalize the shifting effects of individual residues in the GFP based on the responses of both the adiabatic and the diabatic electronic states of the chromophore. We next exhibit that the yellow emitting variant, the Thr203Tyr mutant, generates changes in the electrostatic interactions and an additional π-stacking interaction. These combined effects indeed induce a red shift to emit the fluorescence into the yellow region. With the series of demonstrations, we suggest that our approach can provide sound rationales and useful insights in understanding different responses of various fluorescent complexes, which may be helpful in designing new light emitting proteins and other related systems in future studies.

Use of Genetically-encoded Calcium Indicators for Live Cell Calcium Imaging and Localization in Virus-infected Cells

PubMed Central

Perry, Jacob L.; Ramachandran, Nina K.; Utama, Budi; Hyser, Joseph M.

2015-01-01

Calcium signaling is a ubiquitous and versatile process involved in nearly every cellular process, and exploitation of host calcium signals is a common strategy used by viruses to facilitate replication and cause disease. Small molecule fluorescent calcium dyes have been used by many to examine changes in host cell calcium signaling and calcium channel activation during virus infections, but disadvantages of these dyes, including poor loading and poor long-term retention, complicate analysis of calcium imaging in virus-infected cells due to changes in cell physiology and membrane integrity. The recent expansion of genetically-encoded calcium indicators (GECIs), including blue and red-shifted color variants and variants with calcium affinities appropriate for calcium storage organelles like the endoplasmic reticulum (ER), make the use of GECIs an attractive alternative for calcium imaging in the context of virus infections. Here we describe the development and testing of cell lines stably expressing both green cytoplasmic (GCaMP5G and GCaMP6s) and red ER-targeted (RCEPIAer) GECIs. Using three viruses (rotavirus, poliovirus and respiratory syncytial virus) previously shown to disrupt host calcium homeostasis, we show the GECI cell lines can be used to detect simultaneous cytoplasmic and ER calcium signals. Further, we demonstrate the GECI expression has sufficient stability to enable long-term confocal imaging of both cytoplasmic and ER calcium during the course of virus infections. PMID:26344758

A Fast Variant of 1H Spectroscopic U-FLARE Imaging Using Adjusted Chemical Shift Phase Encoding

NASA Astrophysics Data System (ADS)

Ebel, Andreas; Dreher, Wolfgang; Leibfritz, Dieter

2000-02-01

So far, fast spectroscopic imaging (SI) using the U-FLARE sequence has provided metabolic maps indirectly via Fourier transformation (FT) along the chemical shift (CS) dimension and subsequent peak integration. However, a large number of CS encoding steps Nω is needed to cover the spectral bandwidth and to achieve sufficient spectral resolution for peak integration even if the number of resonance lines is small compared to Nω and even if only metabolic images are of interest and not the spectra in each voxel. Other reconstruction algorithms require extensive prior knowledge, starting values, and/or model functions. An adjusted CS phase encoding scheme (APE) can be used to overcome these drawbacks. It incorporates prior knowledge only about the resonance frequencies present in the sample. Thus, Nω can be reduced by a factor of 4 for many 1H in vivo studies while no spectra have to be reconstructed, and no additional user interaction, prior knowledge, starting values, or model function are required. Phantom measurements and in vivo experiments on rat brain have been performed at 4.7 T to test the feasibility of the method for proton SI.

Quantitative Magnetic Resonance Diffusion-Weighted Imaging Evaluation of the Supratentorial Brain Regions in Patients Diagnosed with Brainstem Variant of Posterior Reversible Encephalopathy Syndrome: A Preliminary Study.

PubMed

Chen, Tai-Yuan; Wu, Te-Chang; Ko, Ching-Chung; Feng, I-Jung; Tsui, Yu-Kun; Lin, Chien-Jen; Chen, Jeon-Hor; Lin, Ching-Po

2017-07-01

Posterior reversible encephalopathy syndrome (PRES) is a clinicoradiologic entity with several causes, characterized by rapid onset of symptoms and typical neuroimaging features, which usually resolve if promptly recognized and treated. Brainstem variant of PRES presents with vasogenic edema in brainstem regions on magnetic resonance (MR) images and there is sparing of the supratentorial regions. Because PRES is usually caused by a hypertensive crisis, which would likely have a systemic effect and global manifestations on the brain tissue, we thus proposed that some microscopic abnormalities of the supratentorial regions could be detected with diffusion-weighted imaging (DWI) using apparent diffusion coefficient (ADC) analysis in brainstem variant of PRES and hypothesized that "normal-looking" supratentorial regions will increase water diffusion. We retrospectively identified patients with PRES who underwent brain magnetic resonance imaging studies. We identified 11 brainstem variants of PRES patients, who formed the study cohort, and 11 typical PRES patients and 20 normal control subjects as the comparison cohorts for this study. Nineteen regions of interest were drawn and systematically placed. The mean ADC values were measured and compared among these 3 groups. ADC values of the typical PRES group were consistently elevated compared with those in normal control subjects. ADC values of the brainstem variant group were consistently elevated compared with those in normal control subjects. ADC values of the typical PRES group and brainstem variant group did not differ significantly, except for the pons area. Quantitative MR DWI may aid in the evaluation of supratentorial microscopic abnormalities in brainstem variant of PRES patients. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Bioluminescence resonance energy transfer (BRET) imaging of protein–protein interactions within deep tissues of living subjects

PubMed Central

Dragulescu-Andrasi, Anca; Chan, Carmel T.; Massoud, Tarik F.; Gambhir, Sanjiv S.

2011-01-01

Identifying protein–protein interactions (PPIs) is essential for understanding various disease mechanisms and developing new therapeutic approaches. Current methods for assaying cellular intermolecular interactions are mainly used for cells in culture and have limited use for the noninvasive assessment of small animal disease models. Here, we describe red light-emitting reporter systems based on bioluminescence resonance energy transfer (BRET) that allow for assaying PPIs both in cell culture and deep tissues of small animals. These BRET systems consist of the recently developed Renilla reniformis luciferase (RLuc) variants RLuc8 and RLuc8.6, used as BRET donors, combined with two red fluorescent proteins, TagRFP and TurboFP635, as BRET acceptors. In addition to the native coelenterazine luciferase substrate, we used the synthetic derivative coelenterazine-v, which further red-shifts the emission maxima of Renilla luciferases by 35 nm. We show the use of these BRET systems for ratiometric imaging of both cells in culture and deep-tissue small animal tumor models and validate their applicability for studying PPIs in mice in the context of rapamycin-induced FK506 binding protein 12 (FKBP12)-FKBP12 rapamycin binding domain (FRB) association. These red light-emitting BRET systems have great potential for investigating PPIs in the context of drug screening and target validation applications. PMID:21730157

Pose-variant facial expression recognition using an embedded image system

NASA Astrophysics Data System (ADS)

Song, Kai-Tai; Han, Meng-Ju; Chang, Shuo-Hung

2008-12-01

In recent years, one of the most attractive research areas in human-robot interaction is automated facial expression recognition. Through recognizing the facial expression, a pet robot can interact with human in a more natural manner. In this study, we focus on the facial pose-variant problem. A novel method is proposed in this paper to recognize pose-variant facial expressions. After locating the face position in an image frame, the active appearance model (AAM) is applied to track facial features. Fourteen feature points are extracted to represent the variation of facial expressions. The distance between feature points are defined as the feature values. These feature values are sent to a support vector machine (SVM) for facial expression determination. The pose-variant facial expression is classified into happiness, neutral, sadness, surprise or anger. Furthermore, in order to evaluate the performance for practical applications, this study also built a low resolution database (160x120 pixels) using a CMOS image sensor. Experimental results show that the recognition rate is 84% with the self-built database.

Bioluminescent system for dynamic imaging of cell and animal behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hara-Miyauchi, Chikako; Laboratory for Cell Function Dynamics, Brain Science Institute, RIKEN, Saitama 351-0198; Department of Biophysics and Biochemistry, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo 113-8510

2012-03-09

Highlights: Black-Right-Pointing-Pointer We combined a yellow variant of GFP and firefly luciferase to make ffLuc-cp156. Black-Right-Pointing-Pointer ffLuc-cp156 showed improved photon yield in cultured cells and transgenic mice. Black-Right-Pointing-Pointer ffLuc-cp156 enabled video-rate bioluminescence imaging of freely-moving animals. Black-Right-Pointing-Pointer ffLuc-cp156 mice enabled tracking real-time drug delivery in conscious animals. -- Abstract: The current utility of bioluminescence imaging is constrained by a low photon yield that limits temporal sensitivity. Here, we describe an imaging method that uses a chemiluminescent/fluorescent protein, ffLuc-cp156, which consists of a yellow variant of Aequorea GFP and firefly luciferase. We report an improvement in photon yield by over threemore » orders of magnitude over current bioluminescent systems. We imaged cellular movement at high resolution including neuronal growth cones and microglial cell protrusions. Transgenic ffLuc-cp156 mice enabled video-rate bioluminescence imaging of freely moving animals, which may provide a reliable assay for drug distribution in behaving animals for pre-clinical studies.« less

GPUs benchmarking in subpixel image registration algorithm

NASA Astrophysics Data System (ADS)

Sanz-Sabater, Martin; Picazo-Bueno, Jose Angel; Micó, Vicente; Ferrerira, Carlos; Granero, Luis; Garcia, Javier

2015-05-01

Image registration techniques are used among different scientific fields, like medical imaging or optical metrology. The straightest way to calculate shifting between two images is using the cross correlation, taking the highest value of this correlation image. Shifting resolution is given in whole pixels which cannot be enough for certain applications. Better results can be achieved interpolating both images, as much as the desired resolution we want to get, and applying the same technique described before, but the memory needed by the system is significantly higher. To avoid memory consuming we are implementing a subpixel shifting method based on FFT. With the original images, subpixel shifting can be achieved multiplying its discrete Fourier transform by a linear phase with different slopes. This method is high time consuming method because checking a concrete shifting means new calculations. The algorithm, highly parallelizable, is very suitable for high performance computing systems. GPU (Graphics Processing Unit) accelerated computing became very popular more than ten years ago because they have hundreds of computational cores in a reasonable cheap card. In our case, we are going to register the shifting between two images, doing the first approach by FFT based correlation, and later doing the subpixel approach using the technique described before. We consider it as `brute force' method. So we will present a benchmark of the algorithm consisting on a first approach (pixel resolution) and then do subpixel resolution approaching, decreasing the shifting step in every loop achieving a high resolution in few steps. This program will be executed in three different computers. At the end, we will present the results of the computation, with different kind of CPUs and GPUs, checking the accuracy of the method, and the time consumed in each computer, discussing the advantages, disadvantages of the use of GPUs.

Sine-squared shifted pulses for recoupling interactions in solid-state NMR

NASA Astrophysics Data System (ADS)

Jain, Mukul G.; Rajalakshmi, G.; Equbal, Asif; Mote, Kaustubh R.; Agarwal, Vipin; Madhu, P. K.

2017-06-01

Rotational-Echo DOuble-Resonance (REDOR) is a versatile experiment for measuring internuclear distance between two heteronuclear spins in solid-state NMR. At slow to intermediate magic-angle spinning (MAS) frequencies, the measurement of distances between strongly coupled spins is challenging due to rapid dephasing of magnetisation. This problem can be remedied by employing the pulse-shifted version of REDOR known as Shifted-REDOR (S-REDOR) that scales down the recoupled dipolar coupling. In this study, we propose a new variant of the REDOR sequence where the positions of the π pulses are determined by a sine-squared function. This new variant has scaling properties similar to S-REDOR. We use theory, numerical simulations, and experiments to compare the dipolar recoupling efficiencies and the experimental robustness of the three REDOR schemes. The proposed variant has advantages in terms of radiofrequency field requirements at fast MAS frequencies.

Shift-Variant Multidimensional Systems.

DTIC Science & Technology

1985-05-29

i=0,1,** *N-1 in (3.1), one will get 0() i_0,1,* ,N-1 which is nonnegative due to the Perron - Frobenius Theorem [24]. That is, the A nonnegativity ...and the current input. The state-space model was extended in order to model 2-D discrete LSV systems with support on a causality cone . Subsequently...formulated as a special system of linear equations with nonnegative coefficients whose solution is required to satisfy con- straints like nonnegativity in

Three-dimensional motion-picture imaging of dynamic object by parallel-phase-shifting digital holographic microscopy using an inverted magnification optical system

NASA Astrophysics Data System (ADS)

Fukuda, Takahito; Shinomura, Masato; Xia, Peng; Awatsuji, Yasuhiro; Nishio, Kenzo; Matoba, Osamu

2017-04-01

We constructed a parallel-phase-shifting digital holographic microscopy (PPSDHM) system using an inverted magnification optical system, and succeeded in three-dimensional (3D) motion-picture imaging for 3D displacement of a microscopic object. In the PPSDHM system, the inverted and afocal magnification optical system consisted of a microscope objective (16.56 mm focal length and 0.25 numerical aperture) and a convex lens (300 mm focal length and 82 mm aperture diameter). A polarization-imaging camera was used to record multiple phase-shifted holograms with a single-shot exposure. We recorded an alum crystal, sinking down in aqueous solution of alum, by the constructed PPSDHM system at 60 frames/s for about 20 s and reconstructed high-quality 3D motion-picture image of the crystal. Then, we calculated amounts of displacement of the crystal from the amounts in the focus plane and the magnifications of the magnification optical system, and obtained the 3D trajectory of the crystal by that amounts.

The remote sensing image segmentation mean shift algorithm parallel processing based on MapReduce

NASA Astrophysics Data System (ADS)

Chen, Xi; Zhou, Liqing

2015-12-01

With the development of satellite remote sensing technology and the remote sensing image data, traditional remote sensing image segmentation technology cannot meet the massive remote sensing image processing and storage requirements. This article put cloud computing and parallel computing technology in remote sensing image segmentation process, and build a cheap and efficient computer cluster system that uses parallel processing to achieve MeanShift algorithm of remote sensing image segmentation based on the MapReduce model, not only to ensure the quality of remote sensing image segmentation, improved split speed, and better meet the real-time requirements. The remote sensing image segmentation MeanShift algorithm parallel processing algorithm based on MapReduce shows certain significance and a realization of value.

Ghost artifact cancellation using phased array processing.

PubMed

Kellman, P; McVeigh, E R

2001-08-01

In this article, a method for phased array combining is formulated which may be used to cancel ghosts caused by a variety of distortion mechanisms, including space variant distortions such as local flow or off-resonance. This method is based on a constrained optimization, which optimizes SNR subject to the constraint of nulling ghost artifacts at known locations. The resultant technique is similar to the method known as sensitivity encoding (SENSE) used for accelerated imaging; however, in this formulation it is applied to full field-of-view (FOV) images. The method is applied to multishot EPI with noninterleaved phase encode acquisition. A number of benefits, as compared to the conventional interleaved approach, are reduced distortion due to off-resonance, in-plane flow, and EPI delay misalignment, as well as eliminating the need for echo-shifting. Experimental results demonstrate the cancellation for both phantom as well as cardiac imaging examples.

Ghost Artifact Cancellation Using Phased Array Processing

PubMed Central

Kellman, Peter; McVeigh, Elliot R.

2007-01-01

In this article, a method for phased array combining is formulated which may be used to cancel ghosts caused by a variety of distortion mechanisms, including space variant distortions such as local flow or off-resonance. This method is based on a constrained optimization, which optimizes SNR subject to the constraint of nulling ghost artifacts at known locations. The resultant technique is similar to the method known as sensitivity encoding (SENSE) used for accelerated imaging; however, in this formulation it is applied to full field-of-view (FOV) images. The method is applied to multishot EPI with noninterleaved phase encode acquisition. A number of benefits, as compared to the conventional interleaved approach, are reduced distortion due to off-resonance, in-plane flow, and EPI delay misalignment, as well as eliminating the need for echo-shifting. Experimental results demonstrate the cancellation for both phantom as well as cardiac imaging examples. PMID:11477638

Optical image security using Stokes polarimetry of spatially variant polarized beam

NASA Astrophysics Data System (ADS)

Fatima, Areeba; Nishchal, Naveen K.

2018-06-01

We propose a novel security scheme that uses vector beam characterized by the spatially variant polarization distribution. A vector beam is so generated that its helical components carry tailored phases corresponding to the image/images that is/are to be encrypted. The tailoring of phase has been done by employing the modified Gerchberg-Saxton algorithm for phase retrieval. Stokes parameters for the final vector beam is evaluated and is used to construct the ciphertext and one of the keys. The advantage of the proposed scheme is that it generates real ciphertext and keys which are easier to transmit and store than complex quantities. Moreover, the known plaintext attack is not applicable to this system. As a proof-of-concept, simulation results have been presented for securing single and double gray-scale images.

The role of noninvasive and invasive diagnostic imaging techniques for detection of extra-cranial venous system anomalies and developmental variants

PubMed Central

2013-01-01

The extra-cranial venous system is complex and not well studied in comparison to the peripheral venous system. A newly proposed vascular condition, named chronic cerebrospinal venous insufficiency (CCSVI), described initially in patients with multiple sclerosis (MS) has triggered intense interest in better understanding of the role of extra-cranial venous anomalies and developmental variants. So far, there is no established diagnostic imaging modality, non-invasive or invasive, that can serve as the “gold standard” for detection of these venous anomalies. However, consensus guidelines and standardized imaging protocols are emerging. Most likely, a multimodal imaging approach will ultimately be the most comprehensive means for screening, diagnostic and monitoring purposes. Further research is needed to determine the spectrum of extra-cranial venous pathology and to compare the imaging findings with pathological examinations. The ability to define and reliably detect noninvasively these anomalies is an essential step toward establishing their incidence and prevalence. The role for these anomalies in causing significant hemodynamic consequences for the intra-cranial venous drainage in MS patients and other neurologic disorders, and in aging, remains unproven. PMID:23806142

Geometric correction method for 3d in-line X-ray phase contrast image reconstruction

PubMed Central

2014-01-01

Background Mechanical system with imperfect or misalignment of X-ray phase contrast imaging (XPCI) components causes projection data misplaced, and thus result in the reconstructed slice images of computed tomography (CT) blurred or with edge artifacts. So the features of biological microstructures to be investigated are destroyed unexpectedly, and the spatial resolution of XPCI image is decreased. It makes data correction an essential pre-processing step for CT reconstruction of XPCI. Methods To remove unexpected blurs and edge artifacts, a mathematics model for in-line XPCI is built by considering primary geometric parameters which include a rotation angle and a shift variant in this paper. Optimal geometric parameters are achieved by finding the solution of a maximization problem. And an iterative approach is employed to solve the maximization problem by using a two-step scheme which includes performing a composite geometric transformation and then following a linear regression process. After applying the geometric transformation with optimal parameters to projection data, standard filtered back-projection algorithm is used to reconstruct CT slice images. Results Numerical experiments were carried out on both synthetic and real in-line XPCI datasets. Experimental results demonstrate that the proposed method improves CT image quality by removing both blurring and edge artifacts at the same time compared to existing correction methods. Conclusions The method proposed in this paper provides an effective projection data correction scheme and significantly improves the image quality by removing both blurring and edge artifacts at the same time for in-line XPCI. It is easy to implement and can also be extended to other XPCI techniques. PMID:25069768

The rotate-plus-shift C-arm trajectory. Part I. Complete data with less than 180° rotation.

PubMed

Ritschl, Ludwig; Kuntz, Jan; Fleischmann, Christof; Kachelrieß, Marc

2016-05-01

In the last decade, C-arm-based cone-beam CT became a widely used modality for intraoperative imaging. Typically a C-arm CT scan is performed using a circular or elliptical trajectory around a region of interest. Therefore, an angular range of at least 180° plus fan angle must be covered to ensure a completely sampled data set. However, mobile C-arms designed with a focus on classical 2D applications like fluoroscopy may be limited to a mechanical rotation range of less than 180° to improve handling and usability. The method proposed in this paper allows for the acquisition of a fully sampled data set with a system limited to a mechanical rotation range of at least 180° minus fan angle using a new trajectory design. This enables CT like 3D imaging with a wide range of C-arm devices which are mainly designed for 2D imaging. The proposed trajectory extends the mechanical rotation range of the C-arm system with two additional linear shifts. Due to the divergent character of the fan-beam geometry, these two shifts lead to an additional angular range of half of the fan angle. Combining one shift at the beginning of the scan followed by a rotation and a second shift, the resulting rotate-plus-shift trajectory enables the acquisition of a completely sampled data set using only 180° minus fan angle of rotation. The shifts can be performed using, e.g., the two orthogonal positioning axes of a fully motorized C-arm system. The trajectory was evaluated in phantom and cadaver examinations using two prototype C-arm systems. The proposed trajectory leads to reconstructions without limited angle artifacts. Compared to the limited angle reconstructions of 180° minus fan angle, image quality increased dramatically. Details in the rotate-plus-shift reconstructions were clearly depicted, whereas they are dominated by artifacts in the limited angle scan. The method proposed here employs 3D imaging using C-arms with less than 180° rotation range adding full 3D functionality to a C-arm device retaining both handling comfort and the usability of 2D imaging. This method has a clear potential for clinical use especially to meet the increasing demand for an intraoperative 3D imaging.

The rotate-plus-shift C-arm trajectory. Part I. Complete data with less than 180° rotation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ritschl, Ludwig; Fleischmann, Christof; Kuntz, Jan, E-mail: j.kuntz@dkfz.de

Purpose: In the last decade, C-arm-based cone-beam CT became a widely used modality for intraoperative imaging. Typically a C-arm CT scan is performed using a circular or elliptical trajectory around a region of interest. Therefore, an angular range of at least 180° plus fan angle must be covered to ensure a completely sampled data set. However, mobile C-arms designed with a focus on classical 2D applications like fluoroscopy may be limited to a mechanical rotation range of less than 180° to improve handling and usability. The method proposed in this paper allows for the acquisition of a fully sampled datamore » set with a system limited to a mechanical rotation range of at least 180° minus fan angle using a new trajectory design. This enables CT like 3D imaging with a wide range of C-arm devices which are mainly designed for 2D imaging. Methods: The proposed trajectory extends the mechanical rotation range of the C-arm system with two additional linear shifts. Due to the divergent character of the fan-beam geometry, these two shifts lead to an additional angular range of half of the fan angle. Combining one shift at the beginning of the scan followed by a rotation and a second shift, the resulting rotate-plus-shift trajectory enables the acquisition of a completely sampled data set using only 180° minus fan angle of rotation. The shifts can be performed using, e.g., the two orthogonal positioning axes of a fully motorized C-arm system. The trajectory was evaluated in phantom and cadaver examinations using two prototype C-arm systems. Results: The proposed trajectory leads to reconstructions without limited angle artifacts. Compared to the limited angle reconstructions of 180° minus fan angle, image quality increased dramatically. Details in the rotate-plus-shift reconstructions were clearly depicted, whereas they are dominated by artifacts in the limited angle scan. Conclusions: The method proposed here employs 3D imaging using C-arms with less than 180° rotation range adding full 3D functionality to a C-arm device retaining both handling comfort and the usability of 2D imaging. This method has a clear potential for clinical use especially to meet the increasing demand for an intraoperative 3D imaging.« less

Red-shifted fluorescent proteins mPlum and mRaspberry and polynucleotides encoding the same

DOEpatents

Tsien, Roger Y [La Jolla, CA; Wang, Lei [San Diego, CA

2008-07-01

Methods using somatic hypermutation (SHM) for producing polypeptide and nucleic acid variants, and nucleic acids encoding such polypeptide variants are disclosed. Such variants may have desired properties. Also disclosed are novel polypeptides, such as improved fluorescent proteins, produced by the novel methods, and nucleic acids, vectors, and host cells comprising such vectors.

Impairment in flexible emotion-based learning in hallucination- and delusion-prone individuals.

PubMed

Cella, Matteo; Dymond, Simon; Cooper, Andrew

2009-11-30

Deficits in emotion-based learning are implicated in many psychiatric disorders. Research conducted with patients with schizophrenia using one of the most popular tasks for the investigation of emotion-based learning, the Iowa Gambling Task (IGT), has largely been inconclusive. The present study employed a novel, contingency-shifting variant IGT with hallucination- and delusion-prone university students to determine whether previous findings were due merely to the presence of psychosis. Following initial screening of a sample of 253 students (mean age = 20.13 years, S.D. = 3.27), 28 high (10 male, 18 female) and 27 low (12 male, 15 female) hallucination-prone and 27 high (7 male, 20 female) and 26 low (11 male, 15 female) delusion-prone individuals completed the contingency-shifting variant IGT. Results showed no significant differences between the performances of high and low hallucination- and delusion-prone individuals during the original phase of the task. Differences only emerged following the onset of the contingency-shift phases, with individuals high in hallucination- and delusion-proneness having impaired performance compared with low hallucination- and delusion-prone individuals. Overall, the present findings demonstrate that impairments associated with hallucination- and delusion-proneness are specific to the shift phase of the contingency-shifting variant IGT, which supports previous findings with patients with schizophrenia.

Circuit design for the retina-like image sensor based on space-variant lens array

NASA Astrophysics Data System (ADS)

Gao, Hongxun; Hao, Qun; Jin, Xuefeng; Cao, Jie; Liu, Yue; Song, Yong; Fan, Fan

2013-12-01

Retina-like image sensor is based on the non-uniformity of the human eyes and the log-polar coordinate theory. It has advantages of high-quality data compression and redundant information elimination. However, retina-like image sensors based on the CMOS craft have drawbacks such as high cost, low sensitivity and signal outputting efficiency and updating inconvenience. Therefore, this paper proposes a retina-like image sensor based on space-variant lens array, focusing on the circuit design to provide circuit support to the whole system. The circuit includes the following parts: (1) A photo-detector array with a lens array to convert optical signals to electrical signals; (2) a strobe circuit for time-gating of the pixels and parallel paths for high-speed transmission of the data; (3) a high-precision digital potentiometer for the I-V conversion, ratio normalization and sensitivity adjustment, a programmable gain amplifier for automatic generation control(AGC), and a A/D converter for the A/D conversion in every path; (4) the digital data is displayed on LCD and stored temporarily in DDR2 SDRAM; (5) a USB port to transfer the data to PC; (6) the whole system is controlled by FPGA. This circuit has advantages as lower cost, larger pixels, updating convenience and higher signal outputting efficiency. Experiments have proved that the grayscale output of every pixel basically matches the target and a non-uniform image of the target is ideally achieved in real time. The circuit can provide adequate technical support to retina-like image sensors based on space-variant lens array.

Comparisons of lesion detectability in ultrasound images acquired using time-shift compensation and spatial compounding.

PubMed

Lacefield, James C; Pilkington, Wayne C; Waag, Robert C

2004-12-01

The effects of aberration, time-shift compensation, and spatial compounding on the discrimination of positive-contrast lesions in ultrasound b-scan images are investigated using a two-dimensional (2-D) array system and tissue-mimicking phantoms. Images were acquired within an 8.8 x 12-mm2 field of view centered on one of four statistically similar 4-mm diameter spherical lesions. Each lesion was imaged in four planes offset by successive 45 degree rotations about the central scan line. Images of the lesions were acquired using conventional geometric focusing through a water path, geometric focusing through a 35-mm thick distributed aberration phantom, and time-shift compensated transmit and receive focusing through the aberration phantom. The views of each lesion were averaged to form sets of water path, aberrated, and time-shift compensated 4:1 compound images and 16:1 compound images. The contrast ratio and detectability index of each image were computed to assess lesion differentiation. In the presence of aberration representative of breast or abdominal wall tissue, time-shift compensation provided statistically significant improvements of contrast ratio but did not consistently affect the detectability index, and spatial compounding significantly increased the detectability index but did not alter the contrast ratio. Time-shift compensation and spatial compounding thus provide complementary benefits to lesion detection.

Image restoration method based on Hilbert transform for full-field optical coherence tomography

NASA Astrophysics Data System (ADS)

Na, Jihoon; Choi, Woo June; Choi, Eun Seo; Ryu, Seon Young; Lee, Byeong Ha

2008-01-01

A full-field optical coherence tomography (FF-OCT) system utilizing a simple but novel image restoration method suitable for a high-speed system is demonstrated. An en-face image is retrieved from only two phase-shifted interference fringe images through using the mathematical Hilbert transform. With a thermal light source, a high-resolution FF-OCT system having axial and transverse resolutions of 1 and 2.2 μm, respectively, was implemented. The feasibility of the proposed scheme is confirmed by presenting the obtained en-face images of biological samples such as a piece of garlic and a gold beetle. The proposed method is robust to the error in the amount of the phase shift and does not leave residual fringes. The use of just two interference images and the strong immunity to phase errors provide great advantages in the imaging speed and the system design flexibility of a high-speed high-resolution FF-OCT system.

Infrared small target tracking based on SOPC

NASA Astrophysics Data System (ADS)

Hu, Taotao; Fan, Xiang; Zhang, Yu-Jin; Cheng, Zheng-dong; Zhu, Bin

2011-01-01

The paper presents a low cost FPGA based solution for a real-time infrared small target tracking system. A specialized architecture is presented based on a soft RISC processor capable of running kernel based mean shift tracking algorithm. Mean shift tracking algorithm is realized in NIOS II soft-core with SOPC (System on a Programmable Chip) technology. Though mean shift algorithm is widely used for target tracking, the original mean shift algorithm can not be directly used for infrared small target tracking. As infrared small target only has intensity information, so an improved mean shift algorithm is presented in this paper. How to describe target will determine whether target can be tracked by mean shift algorithm. Because color target can be tracked well by mean shift algorithm, imitating color image expression, spatial component and temporal component are advanced to describe target, which forms pseudo-color image. In order to improve the processing speed parallel technology and pipeline technology are taken. Two RAM are taken to stored images separately by ping-pong technology. A FLASH is used to store mass temp data. The experimental results show that infrared small target is tracked stably in complicated background.

Image compression-encryption scheme based on hyper-chaotic system and 2D compressive sensing

NASA Astrophysics Data System (ADS)

Zhou, Nanrun; Pan, Shumin; Cheng, Shan; Zhou, Zhihong

2016-08-01

Most image encryption algorithms based on low-dimensional chaos systems bear security risks and suffer encryption data expansion when adopting nonlinear transformation directly. To overcome these weaknesses and reduce the possible transmission burden, an efficient image compression-encryption scheme based on hyper-chaotic system and 2D compressive sensing is proposed. The original image is measured by the measurement matrices in two directions to achieve compression and encryption simultaneously, and then the resulting image is re-encrypted by the cycle shift operation controlled by a hyper-chaotic system. Cycle shift operation can change the values of the pixels efficiently. The proposed cryptosystem decreases the volume of data to be transmitted and simplifies the keys distribution simultaneously as a nonlinear encryption system. Simulation results verify the validity and the reliability of the proposed algorithm with acceptable compression and security performance.

Information theoretic analysis of linear shift-invariant edge-detection operators

NASA Astrophysics Data System (ADS)

Jiang, Bo; Rahman, Zia-ur

2012-06-01

Generally, the designs of digital image processing algorithms and image gathering devices remain separate. Consequently, the performance of digital image processing algorithms is evaluated without taking into account the influences by the image gathering process. However, experiments show that the image gathering process has a profound impact on the performance of digital image processing and the quality of the resulting images. Huck et al. proposed one definitive theoretic analysis of visual communication channels, where the different parts, such as image gathering, processing, and display, are assessed in an integrated manner using Shannon's information theory. We perform an end-to-end information theory based system analysis to assess linear shift-invariant edge-detection algorithms. We evaluate the performance of the different algorithms as a function of the characteristics of the scene and the parameters, such as sampling, additive noise etc., that define the image gathering system. The edge-detection algorithm is regarded as having high performance only if the information rate from the scene to the edge image approaches its maximum possible. This goal can be achieved only by jointly optimizing all processes. Our information-theoretic assessment provides a new tool that allows us to compare different linear shift-invariant edge detectors in a common environment.

Efficient Retrieval of Massive Ocean Remote Sensing Images via a Cloud-Based Mean-Shift Algorithm.

PubMed

Yang, Mengzhao; Song, Wei; Mei, Haibin

2017-07-23

The rapid development of remote sensing (RS) technology has resulted in the proliferation of high-resolution images. There are challenges involved in not only storing large volumes of RS images but also in rapidly retrieving the images for ocean disaster analysis such as for storm surges and typhoon warnings. In this paper, we present an efficient retrieval of massive ocean RS images via a Cloud-based mean-shift algorithm. Distributed construction method via the pyramid model is proposed based on the maximum hierarchical layer algorithm and used to realize efficient storage structure of RS images on the Cloud platform. We achieve high-performance processing of massive RS images in the Hadoop system. Based on the pyramid Hadoop distributed file system (HDFS) storage method, an improved mean-shift algorithm for RS image retrieval is presented by fusion with the canopy algorithm via Hadoop MapReduce programming. The results show that the new method can achieve better performance for data storage than HDFS alone and WebGIS-based HDFS. Speedup and scaleup are very close to linear changes with an increase of RS images, which proves that image retrieval using our method is efficient.

Efficient Retrieval of Massive Ocean Remote Sensing Images via a Cloud-Based Mean-Shift Algorithm

PubMed Central

Song, Wei; Mei, Haibin

2017-01-01

The rapid development of remote sensing (RS) technology has resulted in the proliferation of high-resolution images. There are challenges involved in not only storing large volumes of RS images but also in rapidly retrieving the images for ocean disaster analysis such as for storm surges and typhoon warnings. In this paper, we present an efficient retrieval of massive ocean RS images via a Cloud-based mean-shift algorithm. Distributed construction method via the pyramid model is proposed based on the maximum hierarchical layer algorithm and used to realize efficient storage structure of RS images on the Cloud platform. We achieve high-performance processing of massive RS images in the Hadoop system. Based on the pyramid Hadoop distributed file system (HDFS) storage method, an improved mean-shift algorithm for RS image retrieval is presented by fusion with the canopy algorithm via Hadoop MapReduce programming. The results show that the new method can achieve better performance for data storage than HDFS alone and WebGIS-based HDFS. Speedup and scaleup are very close to linear changes with an increase of RS images, which proves that image retrieval using our method is efficient. PMID:28737699

Stochastic detecting images from strong noise field in visual communications

NASA Astrophysics Data System (ADS)

Cai, Defu

1991-11-01

Random noise interference in image pick-up and image transmission is an important restriction for vision systems. In this paper, interframe shift sampling (IFSS) transform has been used for diminishing noise interference and detecting weak image signal submerged by strong noise in communication systems.

Excitation-resolved wide-field fluorescence imaging of indocyanine green visualizes the microenvironment properties in vivo via solvatochromic shift (Conference Presentation)

NASA Astrophysics Data System (ADS)

Cho, Jaedu; Kim, Chang-Seok; Gulsen, Gultekin

2016-03-01

Near-infrared fluorescence imaging (NIRF) is a powerful wide-field optical imaging tool that has a potential to visualize molecular-specific exogenous fluorescence agents, such as FDA approved Indocyanine Green (ICG), in thick tissue. Indeed, ICG is sensitive to biochemical environment such that it can be used to detect micro- or macroscopic environmental changes in tissue by solvatochromic shift that is defined by the dependence of absorption and emission spectra with the solvent polarity. For example, dimethyl sulfoxide (DMSO) is a very powerful drug carrier that can penetrate biological barriers such as the skin, the membranes, and the blood-brain-barrier. In presence of DMSO, ICG in tissue shows the excitation blue shift. However, NIRF imaging of microenvironment dependent changes of ICG has been challenging for the following reasons. First, the Stoke's shift of ICG is too small to separate the excitation and emission spectra easily. Second, the solvatochromic shift of ICG is too small to be detected by conventional NIRF techniques. Last but not least, the multiple scattering in tissue degrades not only the spatial information but also the spectral contents by the red-shift. We developed a wavelength-swept laser-based NIRF system that can resolve the excitation shift of ICG in tissue such that DMSO can be indirectly visualized. We plan to conduct an in-vivo lymph-node drug-delivery study in a mouse model to show feasibility of the indirect imaging of the drug-carrier with the wavelength-swept-laser based NIRF system.

Application of shift-and-add algorithms for imaging objects within biological media

NASA Astrophysics Data System (ADS)

Aizert, Avishai; Moshe, Tomer; Abookasis, David

2017-01-01

The Shift-and-Add (SAA) technique is a simple mathematical operation developed to reconstruct, at high spatial resolution, atmospherically degraded solar images obtained from stellar speckle interferometry systems. This method shifts and assembles individual degraded short-exposure images into a single average image with significantly improved contrast and detail. Since the inhomogeneous refractive indices of biological tissue causes light scattering similar to that induced by optical turbulence in the atmospheric layers, we assume that SAA methods can be successfully implemented to reconstruct the image of an object within a scattering biological medium. To test this hypothesis, five SAA algorithms were evaluated for reconstructing images acquired from multiple viewpoints. After successfully retrieving the hidden object's shape, quantitative image quality metrics were derived, enabling comparison of imaging error across a spectrum of layer thicknesses, demonstrating the relative efficacy of each SAA algorithm for biological imaging.

Textural characteristics of bone marrow blast nucleus images with different variants of acute lymphoblastic leukemia

NASA Astrophysics Data System (ADS)

Nikitaev, V. G.; Pronichev, A. N.; Polyakov, E. V.; Mozhenkova, A. V.; Tupitsin, N. N.; Frenkel, M. A.

2018-01-01

The paper describes the method of recognition of T - and B - variants of acute lymphoblastic leukemia in microscopic images of blood cells. The method is based on the use of texture characteristics of images. Experimental recognition accuracy evaluation is obtained from the sample of 38 patients (17 with T-ALL and 21 with B-ALL variants of acute lymphoblastic leukemia). The obtained results show the possibility of applying of the proposed approach to the differential diagnosis of T- and B- variants of acute lymphoblastic leukemia.

Neuropsychological Function in a Case of Dandy-Walker Variant in a 68-Year-Old Veteran.

PubMed

Gross, Patricia L; Kays, Jill L; Shura, Robert D

2016-01-01

Dandy-Walker syndrome (DWS) is a congenital brain malformation that is characterized by partial or complete agenesis of the cerebellar vermis and cystic dilatation of the 4th ventricle that shifts ventrolaterally to displace the cerebellar hemispheres. This case is a 68-year-old male veteran with complaints of new-onset cognitive disorder who was found to have previously unsuspected DWS on head computed tomography. This is one of the first case studies to present complete neuropsychological test results in a veteran with DWS. Despite the level of abnormality on imaging, the veteran functioned well until onset of mild cognitive impairments in late adulthood.

SU-E-J-47: Comparison of Online Image Registrations of Varian TrueBeam Cone-Beam CT and BrainLab ExacTrac Imaging Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, J; Shi, W; Andrews, D

2015-06-15

Purpose To compare online image registrations of TrueBeam cone-beam CT (CBCT) and BrainLab ExacTrac imaging systems. Methods Tests were performed on a Varian TrueBeam STx linear accelerator (Version 2.0), which is integrated with a BrainLab ExacTrac imaging system (Version 6.0.5). The study was focused on comparing the online image registrations for translational shifts. A Rando head phantom was placed on treatment couch and immobilized with a BrainLab mask. The phantom was shifted by moving the couch translationally for 8 mm with a step size of 1 mm, in vertical, longitudinal, and lateral directions, respectively. At each location, the phantom wasmore » imaged with CBCT and ExacTrac x-ray. CBCT images were registered with TrueBeam and ExacTrac online registration algorithms, respectively. And ExacTrac x-ray image registrations were performed. Shifts calculated from different registrations were compared with nominal couch shifts. Results The averages and ranges of absolute differences between couch shifts and calculated phantom shifts obtained from ExacTrac x-ray registration, ExacTrac CBCT registration with default window, ExaxTrac CBCT registration with adjusted window (bone), Truebeam CBCT registration with bone window, and Truebeam CBCT registration with soft tissue window, were: 0.07 (0.02–0.14), 0.14 (0.01–0.35), 0.12 (0.02–0.28), 0.09 (0–0.20), and 0.06 (0–0.10) mm, in vertical direction; 0.06 (0.01–0.12), 0.27 (0.07–0.57), 0.23 (0.02–0.48), 0.04 (0–0.10), and 0.08 (0– 0.20) mm, in longitudinal direction; 0.05 (0.01–0.21), 0.35 (0.14–0.80), 0.25 (0.01–0.56), 0.19 (0–0.40), and 0.20 (0–0.40) mm, in lateral direction. Conclusion The shifts calculated from ExacTrac x-ray and TrueBeam CBCT registrations were close to each other (the differences between were less than 0.40 mm in any direction), and had better agreements with couch shifts than those from ExacTrac CBCT registrations. There were no significant differences between TrueBeam CBCT registrations using different windows. In ExacTrac CBCT registrations, using bone window led to better agreements than using default window.« less

Fast registration and reconstruction of aliased low-resolution frames by use of a modified maximum-likelihood approach.

PubMed

Alam, M S; Bognar, J G; Cain, S; Yasuda, B J

1998-03-10

During the process of microscanning a controlled vibrating mirror typically is used to produce subpixel shifts in a sequence of forward-looking infrared (FLIR) images. If the FLIR is mounted on a moving platform, such as an aircraft, uncontrolled random vibrations associated with the platform can be used to generate the shifts. Iterative techniques such as the expectation-maximization (EM) approach by means of the maximum-likelihood algorithm can be used to generate high-resolution images from multiple randomly shifted aliased frames. In the maximum-likelihood approach the data are considered to be Poisson random variables and an EM algorithm is developed that iteratively estimates an unaliased image that is compensated for known imager-system blur while it simultaneously estimates the translational shifts. Although this algorithm yields high-resolution images from a sequence of randomly shifted frames, it requires significant computation time and cannot be implemented for real-time applications that use the currently available high-performance processors. The new image shifts are iteratively calculated by evaluation of a cost function that compares the shifted and interlaced data frames with the corresponding values in the algorithm's latest estimate of the high-resolution image. We present a registration algorithm that estimates the shifts in one step. The shift parameters provided by the new algorithm are accurate enough to eliminate the need for iterative recalculation of translational shifts. Using this shift information, we apply a simplified version of the EM algorithm to estimate a high-resolution image from a given sequence of video frames. The proposed modified EM algorithm has been found to reduce significantly the computational burden when compared with the original EM algorithm, thus making it more attractive for practical implementation. Both simulation and experimental results are presented to verify the effectiveness of the proposed technique.

Effectiveness of a simple and real-time baseline shift monitoring system during stereotactic body radiation therapy of lung tumors.

PubMed

Uchida, Yukihiro; Tachibana, Hidenobu; Kamei, Yoshiyuki; Kashihara, Kenichi

2017-11-01

This study aimed to clinically validate a simple real-time baseline shift monitoring system in a prospective study of consecutive patients undergoing stereotactic body radiation therapy (SBRT) of lung tumors, and to investigate baseline shift due to intrafraction motion of the patient's body during lung SBRT. Ten consecutive patients with peripheral lung tumors were treated by SBRT consisting of four fractions of 12 Gy each, with a total dose of 48 Gy. During treatment, each patient's geometric displacement in the anterior-posterior and left-right directions (the baseline shift) was measured using a real-time monitoring webcam system. Displacement between the start and end of treatment was measured using an X-ray fluoroscopic imaging system. The displacement measurements of the two systems were compared, and the measurements of baseline shift acquired by the monitoring system during treatment were analyzed for all patients. There was no significant deviation between the monitoring system and the X-ray imaging system, with the accuracy of measurement being within 1 mm. Measurements using the monitoring system showed that 7 min of treatment generated displacements of more than 1 mm in 50% of the patients. Baseline shift of a patient's body may be measured accurately in real time, using a monitoring system without X-ray exposure. The manubrium of the sternum is a good location for measuring the baseline shift of a patient's body at all times. The real-time monitoring system may be useful for measuring the baseline shift of a patient's body independently of a gating system. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Constrained optimization of image restoration filters

NASA Technical Reports Server (NTRS)

Riemer, T. E.; Mcgillem, C. D.

1973-01-01

A linear shift-invariant preprocessing technique is described which requires no specific knowledge of the image parameters and which is sufficiently general to allow the effective radius of the composite imaging system to be minimized while constraining other system parameters to remain within specified limits.

Satellite tobacco mosaic virus sequence variants with only five Nucleotide differences can interfere with each other in a cross protection-like phenomenon in plants

USGS Publications Warehouse

Kurath, Gael; Dodds, J. Allan

1994-01-01

The type strain of satellite tobacco mosaic virus (STMV) contains two major variants, designated type 5 (T5) and type 6 (T6), which can be easily distinguished by RNase protection analyses. Clones containing cDNA of representative T5 and T6 STMV genomes have only five single-base differences in the entire 1059-nucleotide genome, and RNA transcribed from each clone is highly infectious when inoculated onto tobacco plants. The different RNase protection assay patterns can be used as genetic markers to identify individual STMV variants and to follow the interactions of variants and their progeny during coinfections in plants. The study described here investigated the effects of coinoculation and various delayed inoculations of T5 and T6 variants on the composition of the progeny STMV populations in systemically infected tobacco tissues. When T5 and T6 STMV RNAs were coinoculated or inoculated with 1-hr delays, the progeny from individual plants most often contained a mixture of T5 and T6 genomes. However, when there was a 24-hr delay between inoculations, the balance of T5 and T6 components in the progeny populations shifted toward predominance of the first variant inoculated. With delays of 3 or 7 days only the first variant was evident in the progeny populations, indicating that established replication of one STMV variant interferes with replication of another in a manner similar to the cross protection phenomenon.

Research on spatial-variant property of bistatic ISAR imaging plane of space target

NASA Astrophysics Data System (ADS)

Guo, Bao-Feng; Wang, Jun-Ling; Gao, Mei-Guo

2015-04-01

The imaging plane of inverse synthetic aperture radar (ISAR) is the projection plane of the target. When taking an image using the range-Doppler theory, the imaging plane may have a spatial-variant property, which causes the change of scatter’s projection position and results in migration through resolution cells. In this study, we focus on the spatial-variant property of the imaging plane of a three-axis-stabilized space target. The innovative contributions are as follows. 1) The target motion model in orbit is provided based on a two-body model. 2) The instantaneous imaging plane is determined by the method of vector analysis. 3) Three Euler angles are introduced to describe the spatial-variant property of the imaging plane, and the image quality is analyzed. The simulation results confirm the analysis of the spatial-variant property. The research in this study is significant for the selection of the imaging segment, and provides the evidence for the following data processing and compensation algorithm. Project supported by the National Natural Science Foundation of China (Grant No. 61401024), the Shanghai Aerospace Science and Technology Innovation Foundation, China (Grant No. SAST201240), and the Basic Research Foundation of Beijing Institute of Technology (Grant No. 20140542001).

Ataxia-telangiectasia gene (ATM) mutation heterozygosity in breast cancer: a narrative review.

PubMed

Jerzak, K J; Mancuso, T; Eisen, A

2018-04-01

Despite the fact that heterozygosity for a pathogenic ATM variant is present in 1%-2% of the adult population, clinical guidelines to inform physicians and genetic counsellors about optimal management in that population are lacking. In this narrative review, we describe the challenges and controversies in the management of women who are heterozygous for a pathogenic ATM variant with respect to screening for breast and other malignancies, to choices for systemic therapy, and to decisions about radiation therapy. Given that the lifetime risk for breast cancer in women who are heterozygous for a pathogenic ATM variant is likely greater than 25%, those women should undergo annual mammographic screening starting at least by 40 years of age. For women in this group who have a strong family history of breast cancer, earlier screening with both magnetic resonance imaging and mammography should be considered. High-quality data to inform the management of established breast cancer in carriers of pathogenic ATM variants are lacking. Although deficiency in the ATM gene product might confer sensitivity to dna-damaging pharmaceuticals such as inhibitors of poly (adp-ribose) polymerase or platinum agents, prospective clinical trials have not been conducted in the relevant patient population. Furthermore, the evidence with respect to radiation therapy is mixed; some data suggest increased toxicity, and other data suggest improved clinical benefit from radiation in women who are carriers of a pathogenic ATM variant. As in the 2017 U.S. National Comprehensive Cancer Network guidelines, we recommend high-risk imaging for women in Ontario who are heterozygous for a pathogenic ATM variant. Currently, ATM carrier status should not influence decisions about systemic or radiation therapy in the setting of an established breast cancer diagnosis.

Habituation, discrimination and anxiety in transgenic mice overexpressing acetylcholinesterase splice variants.

PubMed

Kofman, Ora; Shavit, Yehoshua; Ashkenazi, Sarit; Gabay, Shai

2007-12-14

TgS and TgR transgenic mice overexpress different splice variants of acetylcholinesterase and serve as models for genetic disruption of the cholinergic system. Whereas the TgS mouse overexpresses synaptic AChE, the TgR mouse overexpresses the rare readthrough variant whose C-terminal lacks the cysteine residue which permits adherence to the membrane. The two genotypes were compared to the parent strain, FVB/N mice on locomotion, discrimination learning and anxiety behavior following two exposures to the elevated plus maze. Male TgS mice were slower to acquire a simple odor discrimination, failed to habituate to a novel environment but were not impaired on reversal or set shifting compared to the FVB/N or TgR mice. In addition, TgS mice showed less avoidance behavior on the first exposure and but less exploration on the second exposure to the EPM. TgR mice were not impaired on discrimination learning; however, the females showed excessive running in circles in the activity meter. The findings suggest that the effects of overexpression of AChE are unique to different splice variants and may be sex-dependent.

Performance of Multi-chaotic PSO on a shifted benchmark functions set

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pluhacek, Michal; Senkerik, Roman; Zelinka, Ivan

2015-03-10

In this paper the performance of Multi-chaotic PSO algorithm is investigated using two shifted benchmark functions. The purpose of shifted benchmark functions is to simulate the time-variant real-world problems. The results of chaotic PSO are compared with canonical version of the algorithm. It is concluded that using the multi-chaotic approach can lead to better results in optimization of shifted functions.

Blind restoration of retinal images degraded by space-variant blur with adaptive blur estimation

NASA Astrophysics Data System (ADS)

Marrugo, Andrés. G.; Millán, María. S.; Å orel, Michal; Å roubek, Filip

2013-11-01

Retinal images are often degraded with a blur that varies across the field view. Because traditional deblurring algorithms assume the blur to be space-invariant they typically fail in the presence of space-variant blur. In this work we consider the blur to be both unknown and space-variant. To carry out the restoration, we assume that in small regions the space-variant blur can be approximated by a space-invariant point-spread function (PSF). However, instead of deblurring the image on a per-patch basis, we extend individual PSFs by linear interpolation and perform a global restoration. Because the blind estimation of local PSFs may fail we propose a strategy for the identification of valid local PSFs and perform interpolation to obtain the space-variant PSF. The method was tested on artificial and real degraded retinal images. Results show significant improvement in the visibility of subtle details like small blood vessels.

Surface plasmon resonance imaging system with Mach-Zehnder phase-shift interferometry for DNA micro-array hybridization

NASA Astrophysics Data System (ADS)

Hsiu, Feng-Ming; Chen, Shean-Jen; Tsai, Chien-Hung; Tsou, Chia-Yuan; Su, Y.-D.; Lin, G.-Y.; Huang, K.-T.; Chyou, Jin-Jung; Ku, Wei-Chih; Chiu, S.-K.; Tzeng, C.-M.

2002-09-01

Surface plasmon resonance (SPR) imaging system is presented as a novel technique based on modified Mach-Zehnder phase-shifting interferometry (PSI) for biomolecular interaction analysis (BIA), which measures the spatial phase variation of a resonantly reflected light in biomolecular interaction. In this technique, the micro-array SPR biosensors with over a thousand probe NDA spots can be detected simultaneously. Owing to the feasible and swift measurements, the micro-array SPR biosensors can be extensively applied to the nonspecific adsorption of protein, the membrane/protein interactions, and DNA hybridization. The detection sensitivity of the SPR PSI imaging system is improved to about 1 pg/mm2 for each spot over the conventional SPR imaging systems. The SPR PSI imaging system and its SPR sensors have been successfully used to observe slightly index change in consequence of argon gas flow through the nitrogen in real time, with high sensitivity, and at high-throughout screening rates.

A New Anatomic Variation: Coexistence of Both Dandy-Walker Variant and Ophthalmic Artery Originating From Contralateral Internal Carotid Artery.

PubMed

Ogul, Hayri; Havan, Nuri; Gedikli, Yusuf; Pirimoglu, Berhan; Kantarci, Mecit

2016-06-01

The authors report on 1 patient of variant origin of right ophthalmic artery (OA) from ophthalmic segment of the left internal carotid artery. A 41-year-old man was performed magnetic resonance (MR) imaging and MR angiography. Cerebral MR imaging revealed a Dandy-Walker variant. In MR angiography the authors observed this unusual variant of origin of OA and a complete occlusion of right internal carotid artery. To the authors' knowledge, this is the first patient who has coincidence of both Dandy-Walker variant and origin of OA from contralateral internal carotid artery. Careful observation of MR angiography images with maximum intensity projection is very important for detecting rare vascular variations.

Phase calibration target for quantitative phase imaging with ptychography.

PubMed

Godden, T M; Muñiz-Piniella, A; Claverley, J D; Yacoot, A; Humphry, M J

2016-04-04

Quantitative phase imaging (QPI) utilizes refractive index and thickness variations that lead to optical phase shifts. This gives contrast to images of transparent objects. In quantitative biology, phase images are used to accurately segment cells and calculate properties such as dry mass, volume and proliferation rate. The fidelity of the measured phase shifts is of critical importance in this field. However to date, there has been no standardized method for characterizing the performance of phase imaging systems. Consequently, there is an increasing need for protocols to test the performance of phase imaging systems using well-defined phase calibration and resolution targets. In this work, we present a candidate for a standardized phase resolution target, and measurement protocol for the determination of the transfer of spatial frequencies, and sensitivity of a phase imaging system. The target has been carefully designed to contain well-defined depth variations over a broadband range of spatial frequencies. In order to demonstrate the utility of the target, we measure quantitative phase images on a ptychographic microscope, and compare the measured optical phase shifts with Atomic Force Microscopy (AFM) topography maps and surface profile measurements from coherence scanning interferometry. The results show that ptychography has fully quantitative nanometer sensitivity in optical path differences over a broadband range of spatial frequencies for feature sizes ranging from micrometers to hundreds of micrometers.

A Selective-Echo Method for Chemical-Shift Imaging of Two-Component Systems

NASA Astrophysics Data System (ADS)

Gerald, Rex E., II; Krasavin, Anatoly O.; Botto, Robert E.

A simple and effective method for selectively imaging either one of two chemical species in a two-component system is presented and demonstrated experimentally. The pulse sequence employed, selective- echo chemical- shift imaging (SECSI), is a hybrid (frequency-selective/ T1-contrast) technique that is executed in a short period of time, utilizes the full Boltzmann magnetization of each chemical species to form the corresponding image, and requires only hard pulses of quadrature phase. This approach provides a direct and unambiguous representation of the spatial distribution of the two chemical species. In addition, the performance characteristics and the advantages of the SECSI sequence are compared on a common basis to those of other pulse sequences.

Video flow active control by means of adaptive shifted foveal geometries

NASA Astrophysics Data System (ADS)

Urdiales, Cristina; Rodriguez, Juan A.; Bandera, Antonio J.; Sandoval, Francisco

2000-10-01

This paper presents a control mechanism for video transmission that relies on transmitting non-uniform resolution images depending on the delay of the communication channel. These images are built in an active way to keep the areas of interest of the image at the highest resolution available. In order to shift the area of high resolution over the image and to achieve a data structure easy to process by using conventional algorithms, a shifted fovea multi resolution geometry of adaptive size is used. Besides, if delays are nevertheless too high, the different areas of resolution of the image can be transmitted at different rates. A functional system has been developed for corridor surveillance with static cameras. Tests with real video images have proven that the method allows an almost constant rate of images per second as long as the channel is not collapsed.

Double-image storage optimized by cross-phase modulation in a cold atomic system

NASA Astrophysics Data System (ADS)

Qiu, Tianhui; Xie, Min

2017-09-01

A tripod-type cold atomic system driven by double-probe fields and a coupling field is explored to store double images based on the electromagnetically induced transparency (EIT). During the storage time, an intensity-dependent signal field is applied further to extend the system with the fifth level involved, then the cross-phase modulation is introduced for coherently manipulating the stored images. Both analytical analysis and numerical simulation clearly demonstrate a tunable phase shift with low nonlinear absorption can be imprinted on the stored images, which effectively can improve the visibility of the reconstructed images. The phase shift and the energy retrieving rate of the probe fields are immune to the coupling intensity and the atomic optical density. The proposed scheme can easily be extended to the simultaneous storage of multiple images. This work may be exploited toward the end of EIT-based multiple-image storage devices for all-optical classical and quantum information processings.

Auto-luminescent genetically encoded ratiometric indicator for real-time Ca2+ imaging at the single cell level

NASA Astrophysics Data System (ADS)

Saito, Kenta; Kobayashi, Kentaro; Nagai, Takeharu

2011-12-01

Efficient bioluminescence resonance energy transfer (BRET) from a bioluminescent protein to a fluorescent protein with high fluorescent quantum yield has been utilized to enhance luminescence intensity, allowing single-cell imaging in near real time without external light illumination. We have applied this strategy to develop an autoluminescent Ca2+ indicator, BRAC, which is composed of Ca2+-binding protein, calmodulin, and its target peptide, M13, sandwiched between a yellow fluorescent protein variant, Venus, and an enhanced Renilla luciferase, RLuc8. With this BRAC, we succeeded visualization of Ca2+ dynamics at the single-cell level with temporal resolution at 1 Hz. Moreover, BRAC signals were acquired by ratiometric imaging capable of canceling out Ca2+-independent signal drifts due to change in cell shape, focus shift, etc. Taking advantage of the bioluminescence imaging property that does not require external excitation light, BRAC might become a powerful tool applicable in conjunction with so-called optogenetic technology by which we can control cellular and protein function by light illumination.

Nodal-line dynamics via exact polynomial solutions for coherent waves traversing aberrated imaging systems.

PubMed

Paganin, David M; Beltran, Mario A; Petersen, Timothy C

2018-03-01

We obtain exact polynomial solutions for two-dimensional coherent complex scalar fields propagating through arbitrary aberrated shift-invariant linear imaging systems. These solutions are used to model nodal-line dynamics of coherent fields output by such systems.

High-throughput, image-based screening of pooled genetic variant libraries

PubMed Central

Emanuel, George; Moffitt, Jeffrey R.; Zhuang, Xiaowei

2018-01-01

Image-based, high-throughput screening of genetic perturbations will advance both biology and biotechnology. We report a high-throughput screening method that allows diverse genotypes and corresponding phenotypes to be imaged in numerous individual cells. We achieve genotyping by introducing barcoded genetic variants into cells and using massively multiplexed FISH to measure the barcodes. We demonstrated this method by screening mutants of the fluorescent protein YFAST, yielding brighter and more photostable YFAST variants. PMID:29083401

Preliminary results for mask metrology using spatial heterodyne interferometry

NASA Astrophysics Data System (ADS)

Bingham, Philip R.; Tobin, Kenneth; Bennett, Marylyn H.; Marmillion, Pat

2003-12-01

Spatial heterodyne interferometry (SHI) is an imaging technique that captures both the phase and amplitude of a complex wavefront in a single high-speed image. This technology was developed at the Oak Ridge National Laboratory (ORNL) and is currently being implemented for semiconductor wafer inspection by nLine Corporation. As with any system that measures phase, metrology and inspection of surface structures is possible by capturing a wavefront reflected from the surface. The interpretation of surface structure heights for metrology applications can become very difficult with the many layers of various materials used on semiconductor wafers, so inspection (defect detection) has been the primary focus for semiconductor wafers. However, masks used for photolithography typically only contain a couple well-defined materials opening the doors to high-speed mask metrology in 3 dimensions in addition to inspection. Phase shift masks often contain structures etched out of the transparent substrate material for phase shifting. While these structures are difficult to inspect using only intensity, the phase and amplitude images captured with SHI can produce very good resolution of these structures. The phase images also provide depth information that is crucial for these phase shift regions. Preliminary testing has been performed to determine the feasibility of SHI for high-speed non-contact mask metrology using a prototype SHI system with 532 nm wavelength illumination named the Visible Alpha Tool (VAT). These results show that prototype SHI system is capable of performing critical dimension measurements on 400nm lines with a repeatability of 1.4nm and line height measurements with a repeatability of 0.26nm. Additionally initial imaging of an alternating aperture phase shift mask has shown the ability of SHI to discriminate between typical phase shift heights.

Optical image encryption using chaos-based compressed sensing and phase-shifting interference in fractional wavelet domain

NASA Astrophysics Data System (ADS)

Liu, Qi; Wang, Ying; Wang, Jun; Wang, Qiong-Hua

2018-02-01

In this paper, a novel optical image encryption system combining compressed sensing with phase-shifting interference in fractional wavelet domain is proposed. To improve the encryption efficiency, the volume data of original image are decreased by compressed sensing. Then the compacted image is encoded through double random phase encoding in asymmetric fractional wavelet domain. In the encryption system, three pseudo-random sequences, generated by three-dimensional chaos map, are used as the measurement matrix of compressed sensing and two random-phase masks in the asymmetric fractional wavelet transform. It not only simplifies the keys to storage and transmission, but also enhances our cryptosystem nonlinearity to resist some common attacks. Further, holograms make our cryptosystem be immune to noises and occlusion attacks, which are obtained by two-step-only quadrature phase-shifting interference. And the compression and encryption can be achieved in the final result simultaneously. Numerical experiments have verified the security and validity of the proposed algorithm.

Directed evolution of a monomeric, bright and photostable version of Clavularia cyan fluorescent protein: structural characterization and applications in fluorescence imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al, Hui-wang; Henderson, J. Nathan; Remington, S. James

The arsenal of engineered variants of the GFP [green FP (fluorescent protein)] from Aequorea jellyfish provides researchers with a powerful set of tools for use in biochemical and cell biology research. The recent discovery of diverse FPs in Anthozoa coral species has provided protein engineers with an abundance of alternative progenitor FPs from which improved variants that complement or supersede existing Aequorea GFP variants could be derived. Here, we report the engineering of the first monomeric version of the tetrameric CFP (cyan FP) cFP484 from Clavularia coral. Starting from a designed synthetic gene library with mammalian codon preferences, we identifiedmore » dimeric cFP484 variants with fluorescent brightness significantly greater than the wild-type protein. Following incorporation of dimer-breaking mutations and extensive directed evolution with selection for blue-shifted emission, high fluorescent brightness and photostability, we arrived at an optimized variant that we have named mTFP1 [monomeric TFP1 (teal FP 1)]. The new mTFP1 is one of the brightest and most photostable FPs reported to date. In addition, the fluorescence is insensitive to physiologically relevant pH changes and the fluorescence lifetime decay is best fitted as a single exponential. The 1.19 {angstrom} crystal structure (1 {angstrom}=0.1 nm) of mTFP1 confirms the monomeric structure and reveals an unusually distorted chromophore conformation. As we experimentally demonstrate, the high quantum yield of mTFP1 (0.85) makes it particularly suitable as a replacement for ECFP (enhanced CFP) or Cerulean as a FRET (fluorescence resonance energy transfer) donor to either a yellow or orange FP acceptor.« less

Cystic fibrosis transmembrane conductance regulator (CFTR) allelic variants relate to shifts in faecal microbiota of cystic fibrosis patients.

PubMed

Schippa, Serena; Iebba, Valerio; Santangelo, Floriana; Gagliardi, Antonella; De Biase, Riccardo Valerio; Stamato, Antonella; Bertasi, Serenella; Lucarelli, Marco; Conte, Maria Pia; Quattrucci, Serena

2013-01-01

In this study we investigated the effects of the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene variants on the composition of faecal microbiota, in patients affected by Cystic Fibrosis (CF). CFTR mutations (F508del is the most common) lead to a decreased secretion of chloride/water, and to mucus sticky secretions, in pancreas, respiratory and gastrointestinal tracts. Intestinal manifestations are underestimated in CF, leading to ileum meconium at birth, or small bowel bacterial overgrowth in adult age. Thirty-six CF patients, fasting and under no-antibiotic treatment, were CFTR genotyped on both alleles. Faecal samples were subjected to molecular microbial profiling through Temporal Temperature Gradient Electrophoresis and species-specific PCR. Ecological parameters and multivariate algorithms were employed to find out if CFTR variants could be related to the microbiota structure. Patients were classified by two different criteria: 1) presence/absence of F508del mutation; 2) disease severity in heterozygous and homozygous F508del patients. We found that homozygous-F508del and severe CF patients exhibited an enhanced dysbiotic faecal microbiota composition, even within the CF cohort itself, with higher biodiversity and evenness. We also found, by species-specific PCR, that potentially harmful species (Escherichia coli and Eubacterium biforme) were abundant in homozygous-F508del and severe CF patients, while beneficial species (Faecalibacterium prausnitzii, Bifidobacterium spp., and Eubacterium limosum) were reduced. This is the first report that establishes a link among CFTR variants and shifts in faecal microbiota, opening the way to studies that perceive CF as a 'systemic disease', linking the lung and the gut in a joined axis.

Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Allelic Variants Relate to Shifts in Faecal Microbiota of Cystic Fibrosis Patients

PubMed Central

Santangelo, Floriana; Gagliardi, Antonella; De Biase, Riccardo Valerio; Stamato, Antonella; Bertasi, Serenella; Lucarelli, Marco

2013-01-01

Introduction In this study we investigated the effects of the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene variants on the composition of faecal microbiota, in patients affected by Cystic Fibrosis (CF). CFTR mutations (F508del is the most common) lead to a decreased secretion of chloride/water, and to mucus sticky secretions, in pancreas, respiratory and gastrointestinal tracts. Intestinal manifestations are underestimated in CF, leading to ileum meconium at birth, or small bowel bacterial overgrowth in adult age. Methods Thirty-six CF patients, fasting and under no-antibiotic treatment, were CFTR genotyped on both alleles. Faecal samples were subjected to molecular microbial profiling through Temporal Temperature Gradient Electrophoresis and species-specific PCR. Ecological parameters and multivariate algorithms were employed to find out if CFTR variants could be related to the microbiota structure. Results Patients were classified by two different criteria: 1) presence/absence of F508del mutation; 2) disease severity in heterozygous and homozygous F508del patients. We found that homozygous-F508del and severe CF patients exhibited an enhanced dysbiotic faecal microbiota composition, even within the CF cohort itself, with higher biodiversity and evenness. We also found, by species-specific PCR, that potentially harmful species (Escherichia coli and Eubacterium biforme) were abundant in homozygous-F508del and severe CF patients, while beneficial species (Faecalibacterium prausnitzii, Bifidobacterium spp., and Eubacterium limosum) were reduced. Conclusions This is the first report that establishes a link among CFTR variants and shifts in faecal microbiota, opening the way to studies that perceive CF as a ‘systemic disease’, linking the lung and the gut in a joined axis. PMID:23613805

Experimental evaluation and basis function optimization of the spatially variant image-space PSF on the Ingenuity PET/MR scanner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kotasidis, Fotis A., E-mail: Fotis.Kotasidis@unige.ch; Zaidi, Habib; Geneva Neuroscience Centre, Geneva University, CH-1205 Geneva

2014-06-15

Purpose: The Ingenuity time-of-flight (TF) PET/MR is a recently developed hybrid scanner combining the molecular imaging capabilities of PET with the excellent soft tissue contrast of MRI. It is becoming common practice to characterize the system's point spread function (PSF) and understand its variation under spatial transformations to guide clinical studies and potentially use it within resolution recovery image reconstruction algorithms. Furthermore, due to the system's utilization of overlapping and spherical symmetric Kaiser-Bessel basis functions during image reconstruction, its image space PSF and reconstructed spatial resolution could be affected by the selection of the basis function parameters. Hence, a detailedmore » investigation into the multidimensional basis function parameter space is needed to evaluate the impact of these parameters on spatial resolution. Methods: Using an array of 12 × 7 printed point sources, along with a custom made phantom, and with the MR magnet on, the system's spatially variant image-based PSF was characterized in detail. Moreover, basis function parameters were systematically varied during reconstruction (list-mode TF OSEM) to evaluate their impact on the reconstructed resolution and the image space PSF. Following the spatial resolution optimization, phantom, and clinical studies were subsequently reconstructed using representative basis function parameters. Results: Based on the analysis and under standard basis function parameters, the axial and tangential components of the PSF were found to be almost invariant under spatial transformations (∼4 mm) while the radial component varied modestly from 4 to 6.7 mm. Using a systematic investigation into the basis function parameter space, the spatial resolution was found to degrade for basis functions with a large radius and small shape parameter. However, it was found that optimizing the spatial resolution in the reconstructed PET images, while having a good basis function superposition and keeping the image representation error to a minimum, is feasible, with the parameter combination range depending upon the scanner's intrinsic resolution characteristics. Conclusions: Using the printed point source array as a MR compatible methodology for experimentally measuring the scanner's PSF, the system's spatially variant resolution properties were successfully evaluated in image space. Overall the PET subsystem exhibits excellent resolution characteristics mainly due to the fact that the raw data are not under-sampled/rebinned, enabling the spatial resolution to be dictated by the scanner's intrinsic resolution and the image reconstruction parameters. Due to the impact of these parameters on the resolution properties of the reconstructed images, the image space PSF varies both under spatial transformations and due to basis function parameter selection. Nonetheless, for a range of basis function parameters, the image space PSF remains unaffected, with the range depending on the scanner's intrinsic resolution properties.« less

Photoswitchable red fluorescent protein with a large Stokes shift.

PubMed

Piatkevich, Kiryl D; English, Brian P; Malashkevich, Vladimir N; Xiao, Hui; Almo, Steven C; Singer, Robert H; Verkhusha, Vladislav V

2014-10-23

A subclass of fluorescent proteins (FPs), large Stokes shift (LSS) FP, are characterized by increased spread between excitation and emission maxima. We report a photoswitchable variant of a red FP with an LSS, PSLSSmKate, which initially exhibits excitation and emission at 445 and 622 nm, but violet irradiation photoswitches PSLSSmKate into a common red form with excitation and emission at 573 and 621 nm. We characterize spectral, photophysical, and biochemical properties of PSLSSmKate in vitro and in mammalian cells and determine its crystal structure in the LSS form. Mass spectrometry, mutagenesis, and spectroscopy of PSLSSmKate allow us to propose molecular mechanisms for the LSS, pH dependence, and light-induced chromophore transformation. We demonstrate the applicability of PSLSSmKate to superresolution photoactivated localization microscopy and protein dynamics in live cells. Given its promising properties, we expect that PSLSSmKate-like phenotype will be further used for photoactivatable imaging and tracking multiple populations of intracellular objects.

Learning to Be (In)Variant: Combining Prior Knowledge and Experience to Infer Orientation Invariance in Object Recognition

ERIC Educational Resources Information Center

Austerweil, Joseph L.; Griffiths, Thomas L.; Palmer, Stephen E.

2017-01-01

How does the visual system recognize images of a novel object after a single observation despite possible variations in the viewpoint of that object relative to the observer? One possibility is comparing the image with a prototype for invariance over a relevant transformation set (e.g., translations and dilations). However, invariance over…

A fast two-plus-one phase-shifting algorithm for high-speed three-dimensional shape measurement system

NASA Astrophysics Data System (ADS)

Wang, Wenyun; Guo, Yingfu

2008-12-01

Phase-shifting methods for 3-D shape measurement have long been employed in optical metrology for their speed and accuracy. For real-time, accurate, 3-D shape measurement, a four-step phase-shifting algorithm which has the advantage of its symmetry is a good choice; however, its measurement error is sensitive to any fringe image errors caused by various sources such as motion blur. To alleviate this problem, a fast two-plus-one phase-shifting algorithm is proposed in this paper. This kind of technology will benefit many applications such as medical imaging, gaming, animation, computer vision, computer graphics, etc.

Development and optimization of hardware for delta relaxation enhanced MRI.

PubMed

Harris, Chad T; Handler, William B; Araya, Yonathan; Martínez-Santiesteban, Francisco; Alford, Jamu K; Dalrymple, Brian; Van Sas, Frank; Chronik, Blaine A; Scholl, Timothy J

2014-10-01

Delta relaxation enhanced magnetic resonance (dreMR) imaging requires an auxiliary B0 electromagnet capable of shifting the main magnetic field within a clinical 1.5 Tesla (T) MR system. In this work, the main causes of interaction between an actively shielded, insertable resistive B0 electromagnet and a 1.5T superconducting system are systematically identified and mitigated. The effects of nonideal fabrication of the field-shifting magnet are taken into consideration through careful measurement during winding and improved accuracy in the design of the associated active shield. The shielding performance of the resultant electromagnet is compared against a previously built system in which the shield design was based on an ideal primary coil model. Hardware and software approaches implemented to eliminate residual image artifacts are presented in detail. The eddy currents produced by the newly constructed dreMR system are shown to have a significantly smaller "long-time-constant" component, consistent with the hypothesis that less energy is deposited into the cryostat of the MR system. With active compensation, the dreMR imaging system is capable of 0.22T field shifts within a clinical 1.5T MRI with no significant residual eddy-current fields. Copyright © 2013 Wiley Periodicals, Inc.

Patient-specific estimation of spatially variant image noise for a pinhole cardiac SPECT camera.

PubMed

Cuddy-Walsh, Sarah G; Wells, R Glenn

2018-05-01

New single photon emission computed tomography (SPECT) cameras using fixed pinhole collimation are increasingly popular. Pinhole collimators are known to have variable sensitivity with distance and angle from the pinhole aperture. It follows that pinhole SPECT systems will also have spatially variant sensitivity and hence spatially variant image noise. The objective of this study was to develop and validate a rapid method for analytically estimating a map of the noise magnitude in a reconstructed image using data from a single clinical acquisition. The projected voxel (PV) noise estimation method uses a modified forward projector with attenuation effects to estimate the number of photons detected from each voxel in the field-of-view. We approximate the noise for each voxel as the standard deviation of a Poisson distribution with a mean equal to the number of detected photons. An empirical formula is used to address scaling discrepancies caused by image reconstruction. Calibration coefficients are determined for the PV method by comparing it with noise measured from a nonparametrically bootstrapped set of images of a spherical uniformly filled Tc-99m water phantom. Validation studies compare PV noise estimates with bootstrapped measured noise for 31 patient images (5 min, 340 MBq, 99m Tc-tetrofosmin rest study). Bland-Altman analysis shows R 2 correlations ≥70% between the PV-estimated and -measured image noise. For the 31 patient cardiac images, the PV noise estimate has an average bias of 0.1% compared to bootstrapped noise and have a coefficient of variation (CV) ≤ 17%. The bootstrap approach to noise measurement requires 5 h of computation for each image, whereas the PV noise estimate requires only 64 s. In cardiac images, image noise due to attenuation and camera sensitivity varies on average from 4% at the apex to 9% in the basal posterior region of the heart. The standard deviation between 15 healthy patient study images (including physiological variability in the population) ranges from 6% to 16.5% over the length of the heart. The PV method provides a rapid estimate for spatially variant patient-specific image noise magnitude in a pinhole-collimated dedicated cardiac SPECT camera with a bias of -0.3% and better than 83% precision. © 2018 American Association of Physicists in Medicine.

Measurement of the Band-to-Band Registration of the SNPP VIIRS Imaging System from On-Orbit Data

NASA Technical Reports Server (NTRS)

Tilton, James C.; Lin, Guoqing; Tan, Bin

2016-01-01

The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument was launched 28 October 2011 onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite. The VIIRS instrument is a whiskbroom system with 22 spectral and thermal bands split between 16 moderate resolution bands (M-bands), five imagery resolution bands (I-bands) and a day-night band. In this study we measure the along-scan and along-track band-to-band registration between the I-bands and M-bands from on-orbit data. This measurement is performed by computing the Normalized Mutual Information (NMI) between shifted image band pairs and finding the amount of shift required (if any) to produce the peak in NMI value. Subpixel accuracy is obtained by utilizing bicubic interpolation. Registration shifts are found to be similar to pre-launch measurements and stable (within measurement error) over the instruments first four years in orbit.

On NUFFT-based gridding for non-Cartesian MRI

NASA Astrophysics Data System (ADS)

Fessler, Jeffrey A.

2007-10-01

For MRI with non-Cartesian sampling, the conventional approach to reconstructing images is to use the gridding method with a Kaiser-Bessel (KB) interpolation kernel. Recently, Sha et al. [L. Sha, H. Guo, A.W. Song, An improved gridding method for spiral MRI using nonuniform fast Fourier transform, J. Magn. Reson. 162(2) (2003) 250-258] proposed an alternative method based on a nonuniform FFT (NUFFT) with least-squares (LS) design of the interpolation coefficients. They described this LS_NUFFT method as shift variant and reported that it yielded smaller reconstruction approximation errors than the conventional shift-invariant KB approach. This paper analyzes the LS_NUFFT approach in detail. We show that when one accounts for a certain linear phase factor, the core of the LS_NUFFT interpolator is in fact real and shift invariant. Furthermore, we find that the KB approach yields smaller errors than the original LS_NUFFT approach. We show that optimizing certain scaling factors can lead to a somewhat improved LS_NUFFT approach, but the high computation cost seems to outweigh the modest reduction in reconstruction error. We conclude that the standard KB approach, with appropriate parameters as described in the literature, remains the practical method of choice for gridding reconstruction in MRI.

New generation of meteorology cameras

NASA Astrophysics Data System (ADS)

Janout, Petr; Blažek, Martin; Páta, Petr

2017-12-01

A new generation of the WILLIAM (WIde-field aLL-sky Image Analyzing Monitoring system) camera includes new features such as monitoring of rain and storm clouds during the day observation. Development of the new generation of weather monitoring cameras responds to the demand for monitoring of sudden weather changes. However, new WILLIAM cameras are ready to process acquired image data immediately, release warning against sudden torrential rains, and send it to user's cell phone and email. Actual weather conditions are determined from image data, and results of image processing are complemented by data from sensors of temperature, humidity, and atmospheric pressure. In this paper, we present the architecture, image data processing algorithms of mentioned monitoring camera and spatially-variant model of imaging system aberrations based on Zernike polynomials.

Modelling and restoration of ultrasonic phased-array B-scan images.

PubMed

Ardouin, J P; Venetsanopoulos, A N

1985-10-01

A model is presented for the radio-frequency image produced by a B-scan (pulse-echo) ultrasound imaging system using a phased-array transducer. This type of scanner is widely used for real-time heart imaging. The model allows for dynamic focusing as well as an acoustic lens focusing the beam in the elevation plane. A result of the model is an expression to compute the space-variant point spread function (PSF) of the system. This is made possible by the use of a combination of Fresnel and Fraunhoffer approximations which are valid in the range of interest for practical applications. The PSF is used to design restoration filters in order to improve image resolution. The filters are then applied to experimental images of wires.

A common-path phase-shift interferometry surface plasmon imaging system

NASA Astrophysics Data System (ADS)

Su, Y.-T.; Chen, Shean-Jen; Yeh, T.-L.

2005-03-01

A biosensing imaging system is proposed based on the integration of surface plasmon resonance (SPR) and common-path phase-shift interferometry (PSI) techniques to measure the two-dimensional spatial phase variation caused by biomolecular interactions upon a sensing chip. The SPR phase imaging system can offer high resolution and high-throughout screening capabilities to analyze microarray biomolecular interaction without the need for additional labeling. With the long-term stability advantage of the common-path PSI technique even with external disturbances such as mechanical vibration, buffer flow noise, and laser unstable issue, the system can match the demand of real-time kinetic study for biomolecular interaction analysis (BIA). The SPR-PSI imaging system has achieved a detection limit of 2×10-7 refraction index change, a long-term phase stability of 2.5x10-4π rms over four hours, and a spatial phase resolution of 10-3 π with a lateral resolution of 100μm.

Coarctation of the aorta associated with Dandy–Walker variant

PubMed Central

Zhou, Li; Lui, George K.; Shenoy, Rajesh; Taub, Cynthia C.

2013-01-01

This article reports a rare case of coarctation of the aorta associated with Dandy–Walker variant in a 17-year-old girl. Differential diagnoses of coarctation of the aorta and Dandy–Walker variant are extensively discussed. In addition, standard surgical treatment of coarctation as well as new approaches such as endovascular stenting are described in detail to provide therapeutic insights into her management. Although surgical or endovascular repair of coarctation results in significant improvement of systemic hypertension and is associated with better survival, cardiovascular complications are still very common. Thus, long-term follow-up after repair is required, and high-quality imaging studies such as echocardiography, CT and MRI are warranted. PMID:24396258

Shifting barriers and phenotypic diversification by hybridisation.

PubMed

Sefc, Kristina M; Mattersdorfer, Karin; Ziegelbecker, Angelika; Neuhüttler, Nina; Steiner, Oliver; Goessler, Walter; Koblmüller, Stephan

2017-05-01

The establishment of hybrid taxa relies on reproductive isolation from the parental forms, typically achieved by ecological differentiation. Here, we present an alternative mechanism, in which shifts in the strength and location of dispersal barriers facilitate diversification by hybridisation. Our case study concerns the highly diverse, stenotopic rock-dwelling cichlids of the African Great Lakes, many of which display geographic colour pattern variation. The littoral habitat of these fish has repeatedly been restructured in the course of ancient lake level fluctuations. Genetic data and an experimental cross support the hybrid origin of a distinct yellow-coloured variant of Tropheus moorii from ancient admixture between two allopatric, red and bluish variants. Deficient assortative mating preferences imply that reproductive isolation continues to be contingent on geographic separation. Linking paleolimnological data with the establishment of the hybrid variant, we sketch a selectively neutral diversification process governed solely by rearrangements of dispersal barriers. © 2017 John Wiley & Sons Ltd/CNRS.

Full-field optical coherence tomography image restoration based on Hilbert transformation

NASA Astrophysics Data System (ADS)

Na, Jihoon; Choi, Woo June; Choi, Eun Seo; Ryu, Seon Young; Lee, Byeong Ha

2007-02-01

We propose the envelope detection method that is based on Hilbert transform for image restoration in full-filed optical coherence tomography (FF-OCT). The FF-OCT system presenting a high-axial resolution of 0.9 μm was implemented with a Kohler illuminator based on Linnik interferometer configuration. A 250 W customized quartz tungsten halogen lamp was used as a broadband light source and a CCD camera was used as a 2-dimentional detector array. The proposed image restoration method for FF-OCT requires only single phase-shifting. By using both the original and the phase-shifted images, we could remove the offset and the background signals from the interference fringe images. The desired coherent envelope image was obtained by applying Hilbert transform. With the proposed image restoration method, we demonstrate en-face imaging performance of the implemented FF-OCT system by presenting a tilted mirror surface, an integrated circuit chip, and a piece of onion epithelium.

Substitutions at Amino Acid Positions 143, 148, and 155 of HIV-1 Integrase Define Distinct Genetic Barriers to Raltegravir Resistance In Vivo

PubMed Central

Fransen, Signe; Gupta, Soumi; Frantzell, Arne; Petropoulos, Christos J.

2012-01-01

Mutations at amino acids 143, 148, and 155 in HIV-1 integrase (IN) define primary resistance pathways in subjects failing raltegravir (RAL)-containing treatments. Although each pathway appears to be genetically distinct, shifts in the predominant resistant virus population have been reported under continued drug pressure. To better understand this dynamic, we characterized the RAL susceptibility of 200 resistant viruses, and we performed sequential clonal analysis for selected cases. Patient viruses containing Y143R, Q148R, or Q148H mutations consistently exhibited larger reductions in RAL susceptibility than patient viruses containing N155H mutations. Sequential analyses of virus populations from three subjects revealed temporal shifts in subpopulations representing N155H, Y143R, or Q148H escape pathways. Evaluation of molecular clones isolated from different time points demonstrated that Y143R and Q148H variants exhibited larger reductions in RAL susceptibility and higher IN-mediated replication capacity (RC) than N155H variants within the same subject. Furthermore, shifts from the N155H pathway to either the Q148R or H pathway or the Y143R pathway were dependent on the amino acid substitution at position 148 and the secondary mutations in Y143R- or Q148R- or H-containing variants and correlated with reductions in RAL susceptibility and restorations in RC. Our observations in patient viruses were confirmed by analyzing site-directed mutations. In summary, viruses that acquire mutations defining the 143 or 148 escape pathways are less susceptible to RAL and exhibit greater RC than viruses containing 155 pathway mutations. These selective pressures result in the displacement of N155H variants by 143 or 148 variants under continued drug exposure. PMID:22553340

Self-calibrated correlation imaging with k-space variant correlation functions.

PubMed

Li, Yu; Edalati, Masoud; Du, Xingfu; Wang, Hui; Cao, Jie J

2018-03-01

Correlation imaging is a previously developed high-speed MRI framework that converts parallel imaging reconstruction into the estimate of correlation functions. The presented work aims to demonstrate this framework can provide a speed gain over parallel imaging by estimating k-space variant correlation functions. Because of Fourier encoding with gradients, outer k-space data contain higher spatial-frequency image components arising primarily from tissue boundaries. As a result of tissue-boundary sparsity in the human anatomy, neighboring k-space data correlation varies from the central to the outer k-space. By estimating k-space variant correlation functions with an iterative self-calibration method, correlation imaging can benefit from neighboring k-space data correlation associated with both coil sensitivity encoding and tissue-boundary sparsity, thereby providing a speed gain over parallel imaging that relies only on coil sensitivity encoding. This new approach is investigated in brain imaging and free-breathing neonatal cardiac imaging. Correlation imaging performs better than existing parallel imaging techniques in simulated brain imaging acceleration experiments. The higher speed enables real-time data acquisition for neonatal cardiac imaging in which physiological motion is fast and non-periodic. With k-space variant correlation functions, correlation imaging gives a higher speed than parallel imaging and offers the potential to image physiological motion in real-time. Magn Reson Med 79:1483-1494, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

High-resolution imaging of biological tissue with full-field optical coherence tomography

NASA Astrophysics Data System (ADS)

Zhu, Yue; Gao, Wanrong

2015-03-01

A new full-field optical coherence tomography system with high-resolution has been developed for imaging of cells and tissues. Compared with other FF-OCT (Full-field optical coherence tomography, FF-OCT) systems illuminated with optical fiber bundle, the improved Köhler illumination arrangement with a halogen lamp was used in the proposed FF-OCT system. High numerical aperture microscopic objectives were used for imaging and a piezoelectric ceramic transducer (PZT) was used for phase-shifting. En-face tomographic images can be obtained by applying the five-step phase-shifting algorithm to a series of interferometric images which are recorded by a smart camera. Three-dimensional images can be generated from these tomographic images. Imaging of the chip of Intel Pentium 4 processor demonstrated the ultrahigh resolution of the system (lateral resolution is 0.8μm ), which approaches the theoretical resolution 0.7 μm× 0.5 μm (lateral × axial). En-face images of cells of onion show an excellent performance of the system in generating en-face images of biological tissues. Then, unstained pig stomach was imaged as a tissue and gastric pits could be easily recognized using FF-OCT system. Our study provides evidence for the potential ability of FFOCT in identifying gastric pits from pig stomach tissue. Finally, label-free and unstained ex vivo human liver tissues from both normal and tumor were imaged with this FFOCT system. The results show that the setup has the potential for medical diagnosis applications such liver cancer diagnosis.

B0 concomitant field compensation for MRI systems employing asymmetric transverse gradient coils.

PubMed

Weavers, Paul T; Tao, Shengzhen; Trzasko, Joshua D; Frigo, Louis M; Shu, Yunhong; Frick, Matthew A; Lee, Seung-Kyun; Foo, Thomas K-F; Bernstein, Matt A

2018-03-01

Imaging gradients result in the generation of concomitant fields, or Maxwell fields, which are of increasing importance at higher gradient amplitudes. These time-varying fields cause additional phase accumulation, which must be compensated for to avoid image artifacts. In the case of gradient systems employing symmetric design, the concomitant fields are well described with second-order spatial variation. Gradient systems employing asymmetric design additionally generate concomitant fields with global (zeroth-order or B 0 ) and linear (first-order) spatial dependence. This work demonstrates a general solution to eliminate the zeroth-order concomitant field by applying the correct B 0 frequency shift in real time to counteract the concomitant fields. Results are demonstrated for phase contrast, spiral, echo-planar imaging (EPI), and fast spin-echo imaging. A global phase offset is reduced in the phase-contrast exam, and blurring is virtually eliminated in spiral images. The bulk image shift in the phase-encode direction is compensated for in EPI, whereas signal loss, ghosting, and blurring are corrected in the fast-spin echo images. A user-transparent method to compensate the zeroth-order concomitant field term by center frequency shifting is proposed and implemented. This solution allows all the existing pulse sequences-both product and research-to be retained without any modifications. Magn Reson Med 79:1538-1544, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Efficient determination of the uncertainty for the optimization of SPECT system design: a subsampled fisher information matrix.

PubMed

Fuin, Niccolo; Pedemonte, Stefano; Arridge, Simon; Ourselin, Sebastien; Hutton, Brian F

2014-03-01

System designs in single photon emission tomography (SPECT) can be evaluated based on the fundamental trade-off between bias and variance that can be achieved in the reconstruction of emission tomograms. This trade off can be derived analytically using the Cramer-Rao type bounds, which imply the calculation and the inversion of the Fisher information matrix (FIM). The inverse of the FIM expresses the uncertainty associated to the tomogram, enabling the comparison of system designs. However, computing, storing and inverting the FIM is not practical with 3-D imaging systems. In order to tackle the problem of the computational load in calculating the inverse of the FIM, a method based on the calculation of the local impulse response and the variance, in a single point, from a single row of the FIM, has been previously proposed for system design. However this approximation (circulant approximation) does not capture the global interdependence between the variables in shift-variant systems such as SPECT, and cannot account e.g., for data truncation or missing data. Our new formulation relies on subsampling the FIM. The FIM is calculated over a subset of voxels arranged in a grid that covers the whole volume. Every element of the FIM at the grid points is calculated exactly, accounting for the acquisition geometry and for the object. This new formulation reduces the computational complexity in estimating the uncertainty, but nevertheless accounts for the global interdependence between the variables, enabling the exploration of design spaces hindered by the circulant approximation. The graphics processing unit accelerated implementation of the algorithm reduces further the computation times, making the algorithm a good candidate for real-time optimization of adaptive imaging systems. This paper describes the subsampled FIM formulation and implementation details. The advantages and limitations of the new approximation are explored, in comparison with the circulant approximation, in the context of design optimization of a parallel-hole collimator SPECT system and of an adaptive imaging system (similar to the commercially available D-SPECT).

Easy performance of 6-color confocal immunofluorescence with 4-laser line microscopes.

PubMed

Eissing, Nathalie; Heger, Lukas; Baranska, Anna; Cesnjevar, Robert; Büttner-Herold, Maike; Söder, Stephan; Hartmann, Arndt; Heidkamp, Gordon F; Dudziak, Diana

2014-09-01

Confocal laser scanning microscopy is an advanced technique for imaging tissue samples in vitro and in vivo at high optical resolution. The development of new fluorochrome variants do not only make it possible to perform multicolor flow cytometry of single cells, but in combination with high resolution laser scanning systems also to investigate the distribution of cells in lymphoid tissues by confocal immunofluorescence analyses, thus allowing the distinction of various cell populations directly in the tissue. Here, we provide a protocol for the visualization of at least six differently fluorochrome-labeled antibodies at the same time using a conventional confocal laser scanning microscope with four laser lines (405 nm, 488 nm, 555 nm, and 639 nm laser wavelength) in both murine and human tissue samples. We further demonstrate that compensation correction algorithms are not necessary to reduce spillover of fluorochromes into other channels when the used fluorochromes are combined according to their specific emission bands and the varying Stokes shift for co-excited fluorochromes with the same laser line. Copyright © 2014 Elsevier B.V. All rights reserved.

In Situ alignment system for phase-shifting point-diffraction interferometry

DOEpatents

Goldberg, Kenneth Alan; Naulleau, Patrick P.

2000-01-01

A device and method to facilitate the gross alignment of patterned object- and image-plane masks in optical systems such as the phase-shifting point diffraction interferometer are provided. When an array of similar pinholes or discreet mask fields is used, confusion can occur over the alignment of the focused beams within the field. Adding to the mask pattern a circumscribed or inscribed set of symbols that are identifiable in situ facilitates the unambiguous gross alignment of the object- and/or image-plane masks. Alternatively, a system of markings can be encoded directly into the window shape to accomplish this same task.

Differential Shift Estimation in the Absence of Coherence: Performance Analysis and Benefits of Polarimetry

NASA Astrophysics Data System (ADS)

Villano, Michelangelo; Papathanassiou, Konstantinos P.

2011-03-01

The estimation of the local differential shift between synthetic aperture radar (SAR) images has proven to be an effective technique for monitoring glacier surface motion. As images acquired over glaciers by short wavelength SAR systems, such as TerraSAR-X, often suffer from a lack of coherence, image features have to be exploited for the shift estimation (feature-tracking).The present paper addresses feature-tracking with special attention to the feasibility requirements and the achievable accuracy of the shift estimation. In particular, the dependence of the performance on image characteristics, such as texture parameters, signal-to-noise ratio (SNR) and resolution, as well as on processing techniques (despeckling, normalised cross-correlation versus maximum likelihood estimation) is analysed by means of Monte-Carlo simulations. TerraSAR-X data acquired over the Helheim glacier, Greenland, and the Aletsch glacier, Switzerland, have been processed to validate the simulation results.Feature-tracking can benefit of the availability of fully-polarimetric data. As some image characteristics, in fact, are polarisation-dependent, the selection of an optimum polarisation leads to improved performance. Furthermore, fully-polarimetric SAR images can be despeckled without degrading the resolution, so that additional (smaller-scale) features can be exploited.

Real-time image processing of TOF range images using a reconfigurable processor system

NASA Astrophysics Data System (ADS)

Hussmann, S.; Knoll, F.; Edeler, T.

2011-07-01

During the last years, Time-of-Flight sensors achieved a significant impact onto research fields in machine vision. In comparison to stereo vision system and laser range scanners they combine the advantages of active sensors providing accurate distance measurements and camera-based systems recording a 2D matrix at a high frame rate. Moreover low cost 3D imaging has the potential to open a wide field of additional applications and solutions in markets like consumer electronics, multimedia, digital photography, robotics and medical technologies. This paper focuses on the currently implemented 4-phase-shift algorithm in this type of sensors. The most time critical operation of the phase-shift algorithm is the arctangent function. In this paper a novel hardware implementation of the arctangent function using a reconfigurable processor system is presented and benchmarked against the state-of-the-art CORDIC arctangent algorithm. Experimental results show that the proposed algorithm is well suited for real-time processing of the range images of TOF cameras.

Methodology for the Elimination of Reflection and System Vibration Effects in Particle Image Velocimetry Data Processing

NASA Technical Reports Server (NTRS)

Bremmer, David M.; Hutcheson, Florence V.; Stead, Daniel J.

2005-01-01

A methodology to eliminate model reflection and system vibration effects from post processed particle image velocimetry data is presented. Reflection and vibration lead to loss of data, and biased velocity calculations in PIV processing. A series of algorithms were developed to alleviate these problems. Reflections emanating from the model surface caused by the laser light sheet are removed from the PIV images by subtracting an image in which only the reflections are visible from all of the images within a data acquisition set. The result is a set of PIV images where only the seeded particles are apparent. Fiduciary marks painted on the surface of the test model were used as reference points in the images. By locating the centroids of these marks it was possible to shift all of the images to a common reference frame. This image alignment procedure as well as the subtraction of model reflection are performed in a first algorithm. Once the images have been shifted, they are compared with a background image that was recorded under no flow conditions. The second and third algorithms find the coordinates of fiduciary marks in the acquisition set images and the background image and calculate the displacement between these images. The final algorithm shifts all of the images so that fiduciary mark centroids lie in the same location as the background image centroids. This methodology effectively eliminated the effects of vibration so that unbiased data could be used for PIV processing. The PIV data used for this work was generated at the NASA Langley Research Center Quiet Flow Facility. The experiment entailed flow visualization near the flap side edge region of an airfoil model. Commercial PIV software was used for data acquisition and processing. In this paper, the experiment and the PIV acquisition of the data are described. The methodology used to develop the algorithms for reflection and system vibration removal is stated, and the implementation, testing and validation of these algorithms are presented.

Archimedes' principle for characterisation of recombinant whole cell biocatalysts.

PubMed

Schmitt, Steven; Walser, Marcel; Rehmann, Michael; Oesterle, Sabine; Panke, Sven; Held, Martin

2018-02-14

The ability of whole cells to catalyse multistep reactions, often yielding synthetically demanding compounds later used by industrial biotech or pharma, makes them an indispensable tool of synthetic chemistry. The complex reaction network employed by cellular catalysts and the still only moderate predictive power of modelling approaches leaves this tool challenging to engineer. Frequently, large libraries of semi-rationally generated variants are sampled in high-throughput mode in order to then identify improved catalysts. We present a method for space- and time-efficient processing of very large libraries (10 7 ) of recombinant cellular catalysts, in which the phenotypic characterisation and the isolation of positive variants for the entire library is done within one minute in a single, highly parallelized operation. Specifically, product formation in nanolitre-sized cultivation vessels is sensed and translated into the formation of catalase as a reporter protein. Exposure to hydrogen peroxide leads to oxygen gas formation and thus to a density shift of the cultivation vessel. Exploiting Archimedes' principle, this density shift and the resulting upward buoyancy force can be used for batch-wise library sampling. We demonstrate the potential of the method for both, screening and selection protocols, and envision a wide applicability of the system for biosensor-based assays.

Finite slice analysis (FINA) of sliced and velocity mapped images on a Cartesian grid

NASA Astrophysics Data System (ADS)

Thompson, J. O. F.; Amarasinghe, C.; Foley, C. D.; Rombes, N.; Gao, Z.; Vogels, S. N.; van de Meerakker, S. Y. T.; Suits, A. G.

2017-08-01

Although time-sliced imaging yields improved signal-to-noise and resolution compared with unsliced velocity mapped ion images, for finite slice widths as encountered in real experiments there is a loss of resolution and recovered intensities for the slow fragments. Recently, we reported a new approach that permits correction of these effects for an arbitrarily sliced distribution of a 3D charged particle cloud. This finite slice analysis (FinA) method utilizes basis functions that model the out-of-plane contribution of a given velocity component to the image for sequential subtraction in a spherical polar coordinate system. However, the original approach suffers from a slow processing time due to the weighting procedure needed to accurately model the out-of-plane projection of an anisotropic angular distribution. To overcome this issue we present a variant of the method in which the FinA approach is performed in a cylindrical coordinate system (Cartesian in the image plane) rather than a spherical polar coordinate system. Dubbed C-FinA, we show how this method is applied in much the same manner. We compare this variant to the polar FinA method and find that the processing time (of a 510 × 510 pixel image) in its most extreme case improves by a factor of 100. We also show that although the resulting velocity resolution is not quite as high as the polar version, this new approach shows superior resolution for fine structure in the differential cross sections. We demonstrate the method on a range of experimental and synthetic data at different effective slice widths.

Integration of bioinformatics and imaging informatics for identifying rare PSEN1 variants in Alzheimer's disease.

PubMed

Nho, Kwangsik; Horgusluoglu, Emrin; Kim, Sungeun; Risacher, Shannon L; Kim, Dokyoon; Foroud, Tatiana; Aisen, Paul S; Petersen, Ronald C; Jack, Clifford R; Shaw, Leslie M; Trojanowski, John Q; Weiner, Michael W; Green, Robert C; Toga, Arthur W; Saykin, Andrew J

2016-08-12

Pathogenic mutations in PSEN1 are known to cause familial early-onset Alzheimer's disease (EOAD) but common variants in PSEN1 have not been found to strongly influence late-onset AD (LOAD). The association of rare variants in PSEN1 with LOAD-related endophenotypes has received little attention. In this study, we performed a rare variant association analysis of PSEN1 with quantitative biomarkers of LOAD using whole genome sequencing (WGS) by integrating bioinformatics and imaging informatics. A WGS data set (N = 815) from the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort was used in this analysis. 757 non-Hispanic Caucasian participants underwent WGS from a blood sample and high resolution T1-weighted structural MRI at baseline. An automated MRI analysis technique (FreeSurfer) was used to measure cortical thickness and volume of neuroanatomical structures. We assessed imaging and cerebrospinal fluid (CSF) biomarkers as LOAD-related quantitative endophenotypes. Single variant analyses were performed using PLINK and gene-based analyses of rare variants were performed using the optimal Sequence Kernel Association Test (SKAT-O). A total of 839 rare variants (MAF < 1/√(2 N) = 0.0257) were found within a region of ±10 kb from PSEN1. Among them, six exonic (three non-synonymous) variants were observed. A single variant association analysis showed that the PSEN1 p. E318G variant increases the risk of LOAD only in participants carrying APOE ε4 allele where individuals carrying the minor allele of this PSEN1 risk variant have lower CSF Aβ1-42 and higher CSF tau. A gene-based analysis resulted in a significant association of rare but not common (MAF ≥ 0.0257) PSEN1 variants with bilateral entorhinal cortical thickness. This is the first study to show that PSEN1 rare variants collectively show a significant association with the brain atrophy in regions preferentially affected by LOAD, providing further support for a role of PSEN1 in LOAD. The PSEN1 p. E318G variant increases the risk of LOAD only in APOE ε4 carriers. Integrating bioinformatics with imaging informatics for identification of rare variants could help explain the missing heritability in LOAD.

Bright blue-shifted fluorescent proteins with Cys in the GAF domain engineered from bacterial phytochromes: fluorescence mechanisms and excited-state dynamics.

PubMed

Hontani, Yusaku; Shcherbakova, Daria M; Baloban, Mikhail; Zhu, Jingyi; Verkhusha, Vladislav V; Kennis, John T M

2016-11-18

Near-infrared fluorescent proteins (NIR FPs) engineered from bacterial phytochromes (BphPs) are of great interest for in vivo imaging. They utilize biliverdin (BV) as a chromophore, which is a heme degradation product, and therefore they are straightforward to use in mammalian tissues. Here, we report on fluorescence properties of NIR FPs with key alterations in their BV binding sites. BphP1-FP, iRFP670 and iRFP682 have Cys residues in both PAS and GAF domains, rather than in the PAS domain alone as in wild-type BphPs. We found that NIR FP variants with Cys in the GAF or with Cys in both PAS and GAF show blue-shifted emission with long fluorescence lifetimes. In contrast, mutants with Cys in the PAS only or no Cys residues at all exhibit red-shifted emission with shorter lifetimes. Combining these results with previous biochemical and BphP1-FP structural data, we conclude that BV adducts bound to Cys in the GAF are the origin of bright blue-shifted fluorescence. We propose that the long fluorescence lifetime follows from (i) a sterically more constrained thioether linkage, leaving less mobility for ring A than in canonical BphPs, and (ii) that π-electron conjugation does not extend on ring A, making excited-state deactivation less sensitive to ring A mobility.

Genome-wide association study indicates variants associated with insulin signaling and inflammation mediate lipoprotein responses to fenofibrate

USDA-ARS?s Scientific Manuscript database

A shift towards overall larger very low-density lipoprotein (VLDL), and smaller low-density lipoprotein and high-density lipoprotein (HDL) diameters occurs in insulin resistance (IR), which reflects shifts in the distribution of the subfraction concentrations. Fenofibrate, indicated for hypertriglyc...

TU-FG-BRB-05: A 3 Dimensional Prompt Gamma Imaging System for Range Verification in Proton Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Draeger, E; Chen, H; Polf, J

2016-06-15

Purpose: To report on the initial developments of a clinical 3-dimensional (3D) prompt gamma (PG) imaging system for proton radiotherapy range verification. Methods: The new imaging system under development consists of a prototype Compton camera to measure PG emission during proton beam irradiation and software to reconstruct, display, and analyze 3D images of the PG emission. For initial test of the system, PGs were measured with a prototype CC during a 200 cGy dose delivery with clinical proton pencil beams (ranging from 100 MeV – 200 MeV) to a water phantom. Measurements were also carried out with the CC placedmore » 15 cm from the phantom for a full range 150 MeV pencil beam and with its range shifted by 2 mm. Reconstructed images of the PG emission were displayed by the clinical PG imaging software and compared to the dose distributions of the proton beams calculated by a commercial treatment planning system. Results: Measurements made with the new PG imaging system showed that a 3D image could be reconstructed from PGs measured during the delivery of 200 cGy of dose, and that shifts in the Bragg peak range of as little as 2 mm could be detected. Conclusion: Initial tests of a new PG imaging system show its potential to provide 3D imaging and range verification for proton radiotherapy. Based on these results, we have begun work to improve the system with the goal that images can be produced from delivery of as little as 20 cGy so that the system could be used for in-vivo proton beam range verification on a daily basis.« less

Colour segmentation of multi variants tuberculosis sputum images using self organizing map

NASA Astrophysics Data System (ADS)

Rulaningtyas, Riries; Suksmono, Andriyan B.; Mengko, Tati L. R.; Saptawati, Putri

2017-05-01

Lung tuberculosis detection is still identified from Ziehl-Neelsen sputum smear images in low and middle countries. The clinicians decide the grade of this disease by counting manually the amount of tuberculosis bacilli. It is very tedious for clinicians with a lot number of patient and without standardization for sputum staining. The tuberculosis sputum images have multi variant characterizations in colour, because of no standardization in staining. The sputum has more variants colour and they are difficult to be identified. For helping the clinicians, this research examined the Self Organizing Map method for colouring image segmentation in sputum images based on colour clustering. This method has better performance than k-means clustering which also tried in this research. The Self Organizing Map could segment the sputum images with y good result and cluster the colours adaptively.

Meta-analysis of gene-level tests for rare variant association.

PubMed

Liu, Dajiang J; Peloso, Gina M; Zhan, Xiaowei; Holmen, Oddgeir L; Zawistowski, Matthew; Feng, Shuang; Nikpay, Majid; Auer, Paul L; Goel, Anuj; Zhang, He; Peters, Ulrike; Farrall, Martin; Orho-Melander, Marju; Kooperberg, Charles; McPherson, Ruth; Watkins, Hugh; Willer, Cristen J; Hveem, Kristian; Melander, Olle; Kathiresan, Sekar; Abecasis, Gonçalo R

2014-02-01

The majority of reported complex disease associations for common genetic variants have been identified through meta-analysis, a powerful approach that enables the use of large sample sizes while protecting against common artifacts due to population structure and repeated small-sample analyses sharing individual-level data. As the focus of genetic association studies shifts to rare variants, genes and other functional units are becoming the focus of analysis. Here we propose and evaluate new approaches for performing meta-analysis of rare variant association tests, including burden tests, weighted burden tests, variable-threshold tests and tests that allow variants with opposite effects to be grouped together. We show that our approach retains useful features from single-variant meta-analysis approaches and demonstrate its use in a study of blood lipid levels in ∼18,500 individuals genotyped with exome arrays.

Three dimensional imaging detector employing wavelength-shifting optical fibers

DOEpatents

Worstell, William A.

1997-01-01

A novel detector element structure and method for its use is provided. In a preferred embodiment, one or more inorganic scintillating crystals are coupled through wavelength shifting optical fibers (WLSFs) to position sensitive photomultipliers (PS-PMTs). The superior detector configuration in accordance with this invention is designed for an array of applications in high spatial resolution gamma ray sensing with particular application to SPECT, PET and PVI imaging systems. The design provides better position resolution than prior art devices at a lower total cost. By employing wavelength shifting fibers (WLSFs), the sensor configuration of this invention can operate with a significant reduction in the number of photomultipliers and electronics channels, while potentially improving the resolution of the system by allowing three dimensional reconstruction of energy deposition positions.

Three dimensional imaging detector employing wavelength-shifting optical fibers

DOEpatents

Worstell, W.A.

1997-02-04

A novel detector element structure and method for its use is provided. In a preferred embodiment, one or more inorganic scintillating crystals are coupled through wavelength shifting optical fibers (WLSFs) to position sensitive photomultipliers (PS-PMTs). The superior detector configuration in accordance with this invention is designed for an array of applications in high spatial resolution gamma ray sensing with particular application to SPECT, PET and PVI imaging systems. The design provides better position resolution than prior art devices at a lower total cost. By employing wavelength shifting fibers (WLSFs), the sensor configuration of this invention can operate with a significant reduction in the number of photomultipliers and electronics channels, while potentially improving the resolution of the system by allowing three dimensional reconstruction of energy deposition positions. 11 figs.

Three-dimensional reconstruction from serial sections in PC-Windows platform by using 3D_Viewer.

PubMed

Xu, Yi-Hua; Lahvis, Garet; Edwards, Harlene; Pitot, Henry C

2004-11-01

Three-dimensional (3D) reconstruction from serial sections allows identification of objects of interest in 3D and clarifies the relationship among these objects. 3D_Viewer, developed in our laboratory for this purpose, has four major functions: image alignment, movie frame production, movie viewing, and shift-overlay image generation. Color images captured from serial sections were aligned; then the contours of objects of interest were highlighted in a semi-automatic manner. These 2D images were then automatically stacked at different viewing angles, and their composite images on a projected plane were recorded by an image transform-shift-overlay technique. These composition images are used in the object-rotation movie show. The design considerations of the program and the procedures used for 3D reconstruction from serial sections are described. This program, with a digital image-capture system, a semi-automatic contours highlight method, and an automatic image transform-shift-overlay technique, greatly speeds up the reconstruction process. Since images generated by 3D_Viewer are in a general graphic format, data sharing with others is easy. 3D_Viewer is written in MS Visual Basic 6, obtainable from our laboratory on request.

Nonparaxial and paraxial focusing of azimuthal-variant vector beams.

PubMed

Gu, Bing; Cui, Yiping

2012-07-30

Based on the vectorial Rayleigh-Sommerfeld formulas under the weak nonparaxial approximation, we investigate the propagation behavior of a lowest-order Laguerre-Gaussian beam with azimuthal-variant states of polarization. We present the analytical expressions for the radial, azimuthal, and longitudinal components of the electric field with an arbitrary integer topological charge m focused by a nonaperturing thin lens. We illustrate the three-dimensional optical intensities, energy flux distributions, beam waists, and focal shifts of the focused azimuthal-variant vector beams under the nonparaxial and paraxial approximations.

Image degradation characteristics and restoration based on regularization for diffractive imaging

NASA Astrophysics Data System (ADS)

Zhi, Xiyang; Jiang, Shikai; Zhang, Wei; Wang, Dawei; Li, Yun

2017-11-01

The diffractive membrane optical imaging system is an important development trend of ultra large aperture and lightweight space camera. However, related investigations on physics-based diffractive imaging degradation characteristics and corresponding image restoration methods are less studied. In this paper, the model of image quality degradation for the diffraction imaging system is first deduced mathematically based on diffraction theory and then the degradation characteristics are analyzed. On this basis, a novel regularization model of image restoration that contains multiple prior constraints is established. After that, the solving approach of the equation with the multi-norm coexistence and multi-regularization parameters (prior's parameters) is presented. Subsequently, the space-variant PSF image restoration method for large aperture diffractive imaging system is proposed combined with block idea of isoplanatic region. Experimentally, the proposed algorithm demonstrates its capacity to achieve multi-objective improvement including MTF enhancing, dispersion correcting, noise and artifact suppressing as well as image's detail preserving, and produce satisfactory visual quality. This can provide scientific basis for applications and possesses potential application prospects on future space applications of diffractive membrane imaging technology.

Real time, TV-based, point-image quantizer and sorter

DOEpatents

Case, Arthur L.; Davidson, Jackson B.

1976-01-01

A device is provided for improving the vertical resolution in a television-based, two-dimensional readout for radiation detection systems such as are used to determine the location of light or nuclear radiation impinging a target area viewed by a television camera, where it is desired to store the data indicative of the centroid location of such images. In the example embodiment, impinging nuclear radiation detected in the form of a scintillation occurring in a crystal is stored as a charge image on a television camera tube target. The target is scanned in a raster and the image position is stored according to a corresponding vertical scan number and horizontal position number along the scan. To determine the centroid location of an image that may overlap a number of horizontal scan lines along the vertical axis of the raster, digital logic circuits are provided with at least four series-connected shift registers, each having 512 bit positions according to a selected 512 horizontal increment of resolutions along a scan line. The registers are shifted by clock pulses at a rate of 512 pulses per scan line. When an image or portion thereof is detected along a scan, its horizontal center location is determined and the present front bit is set in the first shift register and shifted through the registers one at a time for each horizontal scan. Each register is compared bit-by-bit with the preceding register to detect coincident set bit positions until the last scan line detecting a portion of the image is determined. Depending on the number of shift registers through which the first detection of the image is shifted, circuitry is provided to store the vertical center position of the event according to the number of shift registers through which the first detection of the event is shifted. Interpolation circuitry is provided to determine if the event centroid is between adjacent scan lines and stored in a vertical address accordingly. The horizontal location of the event is stored in a separate address memory.

Clinical and molecular analysis of GM2 gangliosidosis in two apparent littermate kittens of the Japanese domestic cat.

PubMed

Hasegawa, Daisuke; Yamato, Osamu; Kobayashi, Masanori; Fujita, Michio; Nakamura, Shinichiro; Takahashi, Kimimasa; Satoh, Hiroyuki; Shoda, Toru; Hayashi, Daisuke; Yamasaki, Masahiro; Maede, Yoshimitsu; Arai, Toshiro; Orima, Hiromitsu

2007-06-01

This case report documents clinical and molecular findings in two littermate kittens of the Japanese domestic cat with GM2 gangliosidosis variant 0. Analysis included detailed physical, magnetic resonance imaging, biochemical, pathological and genetic examinations. At first, these littermate kittens showed typical cerebellar signs at approximately 2 months of age. About 2 months later, they progressively showed other neurological signs and subsequently died at about 7 months of age. Magnetic resonance imaging just before the death showed an enlarged ventricular system, T1 hyperintensity in the internal capsule, and T2 hyperintensity in the white matter of the whole brain. Histological findings suggested a type of lysosomal storage disease. Biochemical studies demonstrated that the kittens were affected with GM2 gangliosidosis variant 0, and a DNA assay finally demonstrated that these animals were homozygous for the mutation, which the authors had identified in a different family of the Japanese domestic cat. The findings in the present cases provide useful information about GM2 gangliosidosis variant 0 in Japanese domestic cats.

Anatomic variants in Dandy-Walker complex.

PubMed

Jurcă, Maria Claudia; Kozma, Kinga; Petcheşi, CodruŢa Diana; Bembea, Marius; Pop, Ovidiu Laurean; MuŢiu, Gabriela; Coroi, Mihaela Cristiana; Jurcă, Alexandru Daniel; Dobjanschi, Luciana

2017-01-01

Dandy-Walker complex (DWC) is a malformative association of the central nervous system. DWC includes four different types: Dandy-Walker malformation (vermis agenesis or hypoplasia, cystic dilatation of the fourth ventricle and a large posterior fossa); Dandy-Walker variant (vermis hypoplasia, cystic dilatation of the fourth ventricle, normal posterior fossa); mega cysterna magna (large posterior fossa, normal vermis and fourth ventricle) and posterior fossa arachnoid cyst. We present and discuss four cases with different morphological and clinical forms of the Dandy-Walker complex. In all four cases, diagnosis was reached by incorporation of clinical (macrocephaly, seizures) and imaging [X-ray, computed tomography (CT), magnetic resonance imaging (MRI)] data. Two patients were diagnosed with Dandy-Walker complex, one patient was diagnosed with Dandy-Walker variant in a rare association with neurofibromatosis and one patient was diagnosed with a posterior fossa arachnoid cyst associated with left-sided Claude Bernard-Horner syndrome, congenital heart disease (coarctation of the aorta, mitral stenosis) and gastroesophageal reflux. In all forms of DWC, the clinical, radiological and functional manifestations are variable and require adequate diagnostic and therapeutic measures.

Improved image quality in pinhole SPECT by accurate modeling of the point spread function in low magnification systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pino, Francisco; Roé, Nuria; Aguiar, Pablo, E-mail: pablo.aguiar.fernandez@sergas.es

2015-02-15

Purpose: Single photon emission computed tomography (SPECT) has become an important noninvasive imaging technique in small-animal research. Due to the high resolution required in small-animal SPECT systems, the spatially variant system response needs to be included in the reconstruction algorithm. Accurate modeling of the system response should result in a major improvement in the quality of reconstructed images. The aim of this study was to quantitatively assess the impact that an accurate modeling of spatially variant collimator/detector response has on image-quality parameters, using a low magnification SPECT system equipped with a pinhole collimator and a small gamma camera. Methods: Threemore » methods were used to model the point spread function (PSF). For the first, only the geometrical pinhole aperture was included in the PSF. For the second, the septal penetration through the pinhole collimator was added. In the third method, the measured intrinsic detector response was incorporated. Tomographic spatial resolution was evaluated and contrast, recovery coefficients, contrast-to-noise ratio, and noise were quantified using a custom-built NEMA NU 4–2008 image-quality phantom. Results: A high correlation was found between the experimental data corresponding to intrinsic detector response and the fitted values obtained by means of an asymmetric Gaussian distribution. For all PSF models, resolution improved as the distance from the point source to the center of the field of view increased and when the acquisition radius diminished. An improvement of resolution was observed after a minimum of five iterations when the PSF modeling included more corrections. Contrast, recovery coefficients, and contrast-to-noise ratio were better for the same level of noise in the image when more accurate models were included. Ring-type artifacts were observed when the number of iterations exceeded 12. Conclusions: Accurate modeling of the PSF improves resolution, contrast, and recovery coefficients in the reconstructed images. To avoid the appearance of ring-type artifacts, the number of iterations should be limited. In low magnification systems, the intrinsic detector PSF plays a major role in improvement of the image-quality parameters.« less

Practical aspects of modern interferometry for optical manufacturing quality control: Part 2

NASA Astrophysics Data System (ADS)

Smythe, Robert

2012-07-01

Modern phase shifting interferometers enable the manufacture of optical systems that drive the global economy. Semiconductor chips, solid-state cameras, cell phone cameras, infrared imaging systems, space based satellite imaging and DVD and Blu-Ray disks are all enabled by phase shifting interferometers. Theoretical treatments of data analysis and instrument design advance the technology but often are not helpful towards the practical use of interferometers. An understanding of the parameters that drive system performance is critical to produce useful results. Any interferometer will produce a data map and results; this paper, in three parts, reviews some of the key issues to minimize error sources in that data and provide a valid measurement.

Practical aspects of modern interferometry for optical manufacturing quality control, Part 3

NASA Astrophysics Data System (ADS)

Smythe, Robert A.

2012-09-01

Modern phase shifting interferometers enable the manufacture of optical systems that drive the global economy. Semiconductor chips, solid-state cameras, cell phone cameras, infrared imaging systems, space-based satellite imaging, and DVD and Blu-Ray disks are all enabled by phase-shifting interferometers. Theoretical treatments of data analysis and instrument design advance the technology but often are not helpful toward the practical use of interferometers. An understanding of the parameters that drive the system performance is critical to produce useful results. Any interferometer will produce a data map and results; this paper, in three parts, reviews some of the key issues to minimize error sources in that data and provide a valid measurement.

Usefulness of a Darwinian System in a Biotechnological Application: Evolution of Optical Window Fluorescent Protein Variants under Selective Pressure

PubMed Central

Ng, David; Pauli, Jutta; Resch-Genger, Ute; Kühn, Enrico; Heuer, Steffen; Beisker, Wolfgang; Köster, Reinhard W.; Zitzelsberger, Horst; Caldwell, Randolph B

2014-01-01

With rare exceptions, natural evolution is an extremely slow process. One particularly striking exception in the case of protein evolution is in the natural production of antibodies. Developing B cells activate and diversify their immunoglobulin (Ig) genes by recombination, gene conversion (GC) and somatic hypermutation (SHM). Iterative cycles of hypermutation and selection continue until antibodies of high antigen binding specificity emerge (affinity maturation). The avian B cell line DT40, a cell line which is highly amenable to genetic manipulation and exhibits a high rate of targeted integration, utilizes both GC and SHM. Targeting the DT40's diversification machinery onto transgenes of interest inserted into the Ig loci and coupling selective pressure based on the desired outcome mimics evolution. Here we further demonstrate the usefulness of this platform technology by selectively pressuring a large shift in the spectral properties of the fluorescent protein eqFP615 into the highly stable and advanced optical imaging expediting fluorescent protein Amrose. The method is advantageous as it is time and cost effective and no prior knowledge of the outcome protein's structure is necessary. Amrose was evolved to have high excitation at 633 nm and excitation/emission into the far-red, which is optimal for whole-body and deep tissue imaging as we demonstrate in the zebrafish and mouse model. PMID:25192257

Usefulness of a Darwinian system in a biotechnological application: evolution of optical window fluorescent protein variants under selective pressure.

PubMed

Schoetz, Ulrike; Deliolanis, Nikolaos C; Ng, David; Pauli, Jutta; Resch-Genger, Ute; Kühn, Enrico; Heuer, Steffen; Beisker, Wolfgang; Köster, Reinhard W; Zitzelsberger, Horst; Caldwell, Randolph B

2014-01-01

With rare exceptions, natural evolution is an extremely slow process. One particularly striking exception in the case of protein evolution is in the natural production of antibodies. Developing B cells activate and diversify their immunoglobulin (Ig) genes by recombination, gene conversion (GC) and somatic hypermutation (SHM). Iterative cycles of hypermutation and selection continue until antibodies of high antigen binding specificity emerge (affinity maturation). The avian B cell line DT40, a cell line which is highly amenable to genetic manipulation and exhibits a high rate of targeted integration, utilizes both GC and SHM. Targeting the DT40's diversification machinery onto transgenes of interest inserted into the Ig loci and coupling selective pressure based on the desired outcome mimics evolution. Here we further demonstrate the usefulness of this platform technology by selectively pressuring a large shift in the spectral properties of the fluorescent protein eqFP615 into the highly stable and advanced optical imaging expediting fluorescent protein Amrose. The method is advantageous as it is time and cost effective and no prior knowledge of the outcome protein's structure is necessary. Amrose was evolved to have high excitation at 633 nm and excitation/emission into the far-red, which is optimal for whole-body and deep tissue imaging as we demonstrate in the zebrafish and mouse model.

Proton nuclear magnetic resonance characterization of the aromatic residues in the variant-3 neurotoxin from Centruroides sculpturatus Ewing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishna, N.R.; Nettesheim, D.G.; Klevit, R.E.

1989-02-21

The amino acid sequence for the variant-3 (CsE-v3) toxin from the venom of the scorpion Centruroides sculpturatus Ewing contains eight aromatic residues. By use of 2D NMR spectroscopic methods, the resonances from the individual protons (NH, C{sup alpha}H, C{sup beta}H{prime}, H{double prime}, and the ring) for each of the individual aromatic residues have been completely assigned. The spatial arrangement of the aromatic ring systems with respect to each other has been qualitatively analyzed by 2D-NOESY techniques. The results show that Trp-47, Tyr-4, and Tyr-42 are in close spatial proximity to each other. The NOESY contacts and the ring current inducedmore » shifts in the resonances of the individual protons of Tyr-4 and Trp-47 suggest that the aromatic ring planes of these residues are in an orthogonal arrangement. A comparison with the published crystal structure suggests that there is a minor rearrangement of the aromatic rings in the solution phase. No 2D-NOESY contacts involving Phe-44 and Tyr-14 to any other aromatic ring protons have been observed. The pH dependence of the aromatic ring proton chemical shifts has also been studied. These results suggest that the Tyr-58 phenolic group is experiencing a hydrogen-bonding interaction with a positively charged group, while Tyr-4, -14, -38, and -40 are experiencing through-space interactions with proximal negatively charged groups. These studies define the microenvironment of the aromatic residues in the variant-3 neurotoxin in aqueous solution.« less

Quantifying attention shifts in augmented reality image-guided neurosurgery

PubMed Central

Drouin, Simon; Collins, D. Louis; Popa, Tiberiu; Kersten-Oertel, Marta

2017-01-01

Image-guided surgery (IGS) has allowed for more minimally invasive procedures, leading to better patient outcomes, reduced risk of infection, less pain, shorter hospital stays and faster recoveries. One drawback that has emerged with IGS is that the surgeon must shift their attention from the patient to the monitor for guidance. Yet both cognitive and motor tasks are negatively affected with attention shifts. Augmented reality (AR), which merges the realworld surgical scene with preoperative virtual patient images and plans, has been proposed as a solution to this drawback. In this work, we studied the impact of two different types of AR IGS set-ups (mobile AR and desktop AR) and traditional navigation on attention shifts for the specific task of craniotomy planning. We found a significant difference in terms of the time taken to perform the task and attention shifts between traditional navigation, but no significant difference between the different AR set-ups. With mobile AR, however, users felt that the system was easier to use and that their performance was better. These results suggest that regardless of where the AR visualisation is shown to the surgeon, AR may reduce attention shifts, leading to more streamlined and focused procedures. PMID:29184663

Quantifying attention shifts in augmented reality image-guided neurosurgery.

PubMed

Léger, Étienne; Drouin, Simon; Collins, D Louis; Popa, Tiberiu; Kersten-Oertel, Marta

2017-10-01

Image-guided surgery (IGS) has allowed for more minimally invasive procedures, leading to better patient outcomes, reduced risk of infection, less pain, shorter hospital stays and faster recoveries. One drawback that has emerged with IGS is that the surgeon must shift their attention from the patient to the monitor for guidance. Yet both cognitive and motor tasks are negatively affected with attention shifts. Augmented reality (AR), which merges the realworld surgical scene with preoperative virtual patient images and plans, has been proposed as a solution to this drawback. In this work, we studied the impact of two different types of AR IGS set-ups (mobile AR and desktop AR) and traditional navigation on attention shifts for the specific task of craniotomy planning. We found a significant difference in terms of the time taken to perform the task and attention shifts between traditional navigation, but no significant difference between the different AR set-ups. With mobile AR, however, users felt that the system was easier to use and that their performance was better. These results suggest that regardless of where the AR visualisation is shown to the surgeon, AR may reduce attention shifts, leading to more streamlined and focused procedures.

Development of a digital-micromirror-device-based multishot snapshot spectral imaging system.

PubMed

Wu, Yuehao; Mirza, Iftekhar O; Arce, Gonzalo R; Prather, Dennis W

2011-07-15

We report on the development of a digital-micromirror-device (DMD)-based multishot snapshot spectral imaging (DMD-SSI) system as an alternative to current piezostage-based multishot coded aperture snapshot spectral imager (CASSI) systems. In this system, a DMD is used to implement compressive sensing (CS) measurement patterns for reconstructing the spatial/spectral information of an imaging scene. Based on the CS measurement results, we demonstrated the concurrent reconstruction of 24 spectral images. The DMD-SSI system is versatile in nature as it can be used to implement independent CS measurement patterns in addition to spatially shifted patterns that piezostage-based systems can offer. © 2011 Optical Society of America

MARS-MD: rejection based image domain material decomposition

NASA Astrophysics Data System (ADS)

Bateman, C. J.; Knight, D.; Brandwacht, B.; McMahon, J.; Healy, J.; Panta, R.; Aamir, R.; Rajendran, K.; Moghiseh, M.; Ramyar, M.; Rundle, D.; Bennett, J.; de Ruiter, N.; Smithies, D.; Bell, S. T.; Doesburg, R.; Chernoglazov, A.; Mandalika, V. B. H.; Walsh, M.; Shamshad, M.; Anjomrouz, M.; Atharifard, A.; Vanden Broeke, L.; Bheesette, S.; Kirkbride, T.; Anderson, N. G.; Gieseg, S. P.; Woodfield, T.; Renaud, P. F.; Butler, A. P. H.; Butler, P. H.

2018-05-01

This paper outlines image domain material decomposition algorithms that have been routinely used in MARS spectral CT systems. These algorithms (known collectively as MARS-MD) are based on a pragmatic heuristic for solving the under-determined problem where there are more materials than energy bins. This heuristic contains three parts: (1) splitting the problem into a number of possible sub-problems, each containing fewer materials; (2) solving each sub-problem; and (3) applying rejection criteria to eliminate all but one sub-problem's solution. An advantage of this process is that different constraints can be applied to each sub-problem if necessary. In addition, the result of this process is that solutions will be sparse in the material domain, which reduces crossover of signal between material images. Two algorithms based on this process are presented: the Segmentation variant, which uses segmented material classes to define each sub-problem; and the Angular Rejection variant, which defines the rejection criteria using the angle between reconstructed attenuation vectors.

Magnetic resonance imaging findings are useful for evaluating the three-dimensional development and follow-up of linear lupus erythematosus profundus.

PubMed

Ogawa, M; Muro, Y; Sugiura, K; Sakakibara, A; Akiyama, M

2015-10-01

Lupus erythematosus profundus (LEP), which is a variant of chronic cutaneous lupus erythematosus (CLE), is seen in approximately 2∼3% of CLE patients, and only 10% to 20% of LEP patients present with systemic LE (SLE). LEP shows subcutaneous nodules with or without discoid LE (DLE). Linear LEP, a very rare variant of LEP, was first reported in 1991 in Japanese and in 1998 in English. Since LEP sometimes leaves skin depressions or scars as a result of atrophy of adipose tissue, early and adequate treatments are necessary. Here, we introduce an LEP case in which magnetic resonance imaging (MRI) was quite effective in evaluating a lesion that had been considered to be linear DLE. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Common Genetic Variation Near Melatonin Receptor 1A Gene Linked to Job-Related Exhaustion in Shift Workers

PubMed Central

Sulkava, Sonja; Ollila, Hanna M.; Alasaari, Jukka; Puttonen, Sampsa; Härmä, Mikko; Viitasalo, Katriina; Lahtinen, Alexandra; Lindström, Jaana; Toivola, Auli; Sulkava, Raimo; Kivimäki, Mika; Vahtera, Jussi; Partonen, Timo; Silander, Kaisa; Porkka-Heiskanen, Tarja

2017-01-01

Abstract Study Objectives: Tolerance to shift work varies; only some shift workers suffer from disturbed sleep, fatigue, and job-related exhaustion. Our aim was to explore molecular genetic risk factors for intolerance to shift work. Methods: We assessed intolerance to shift work with job-related exhaustion symptoms in shift workers using the emotional exhaustion subscale of the Maslach Burnout Inventory-General Survey, and carried out a genome-wide association study (GWAS) using Illumina’s Human610-Quad BeadChip (n = 176). The most significant findings were further studied in three groups of Finnish shift workers (n = 577). We assessed methylation in blood cells with the Illumina HumanMethylation450K BeadChip, and examined gene expression levels in the publicly available eGWAS Mayo data. Results: The second strongest signal identified in the GWAS (p = 2.3 × 10E-6) was replicated in two of the replication studies with p < .05 (p = 2.0 × 10E-4 when combining the replication studies) and indicated an association of job-related exhaustion in shift workers with rs12506228, located downstream of the melatonin receptor 1A gene (MTNR1A). The risk allele was also associated with reduced in silico gene expression levels of MTNR1A in brain tissue and suggestively associated with changes in DNA methylation in the 5' regulatory region of MTNR1A. Conclusions: These findings suggest that a variant near MTNR1A may be associated with job-related exhaustion in shift workers. The risk variant may exert its effect via epigenetic mechanisms, potentially leading to reduced melatonin signaling in the brain. These results could indicate a link between melatonin signaling, a key circadian regulatory mechanism, and tolerance to shift work. PMID:28364478

Seamless tiled display system

NASA Technical Reports Server (NTRS)

Dubin, Matthew B. (Inventor); Larson, Brent D. (Inventor); Kolosowsky, Aleksandra (Inventor)

2006-01-01

A modular and scalable seamless tiled display apparatus includes multiple display devices, a screen, and multiple lens assemblies. Each display device is subdivided into multiple sections, and each section is configured to display a sectional image. One of the lens assemblies is optically coupled to each of the sections of each of the display devices to project the sectional image displayed on that section onto the screen. The multiple lens assemblies are configured to merge the projected sectional images to form a single tiled image. The projected sectional images may be merged on the screen by magnifying and shifting the images in an appropriate manner. The magnification and shifting of these images eliminates any visual effect on the tiled display that may result from dead-band regions defined between each pair of adjacent sections on each display device, and due to gaps between multiple display devices.

Two-level image authentication by two-step phase-shifting interferometry and compressive sensing

NASA Astrophysics Data System (ADS)

Zhang, Xue; Meng, Xiangfeng; Yin, Yongkai; Yang, Xiulun; Wang, Yurong; Li, Xianye; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi

2018-01-01

A two-level image authentication method is proposed; the method is based on two-step phase-shifting interferometry, double random phase encoding, and compressive sensing (CS) theory, by which the certification image can be encoded into two interferograms. Through discrete wavelet transform (DWT), sparseness processing, Arnold transform, and data compression, two compressed signals can be generated and delivered to two different participants of the authentication system. Only the participant who possesses the first compressed signal attempts to pass the low-level authentication. The application of Orthogonal Match Pursuit CS algorithm reconstruction, inverse Arnold transform, inverse DWT, two-step phase-shifting wavefront reconstruction, and inverse Fresnel transform can result in the output of a remarkable peak in the central location of the nonlinear correlation coefficient distributions of the recovered image and the standard certification image. Then, the other participant, who possesses the second compressed signal, is authorized to carry out the high-level authentication. Therefore, both compressed signals are collected to reconstruct the original meaningful certification image with a high correlation coefficient. Theoretical analysis and numerical simulations verify the feasibility of the proposed method.

Interferometric imaging of acoustical phenomena using high-speed polarization camera and 4-step parallel phase-shifting technique

NASA Astrophysics Data System (ADS)

Ishikawa, K.; Yatabe, K.; Ikeda, Y.; Oikawa, Y.; Onuma, T.; Niwa, H.; Yoshii, M.

2017-02-01

Imaging of sound aids the understanding of the acoustical phenomena such as propagation, reflection, and diffraction, which is strongly required for various acoustical applications. The imaging of sound is commonly done by using a microphone array, whereas optical methods have recently been interested due to its contactless nature. The optical measurement of sound utilizes the phase modulation of light caused by sound. Since light propagated through a sound field changes its phase as proportional to the sound pressure, optical phase measurement technique can be used for the sound measurement. Several methods including laser Doppler vibrometry and Schlieren method have been proposed for that purpose. However, the sensitivities of the methods become lower as a frequency of sound decreases. In contrast, since the sensitivities of the phase-shifting technique do not depend on the frequencies of sounds, that technique is suitable for the imaging of sounds in the low-frequency range. The principle of imaging of sound using parallel phase-shifting interferometry was reported by the authors (K. Ishikawa et al., Optics Express, 2016). The measurement system consists of a high-speed polarization camera made by Photron Ltd., and a polarization interferometer. This paper reviews the principle briefly and demonstrates the high-speed imaging of acoustical phenomena. The results suggest that the proposed system can be applied to various industrial problems in acoustical engineering.

Detection of unmanned aerial vehicles using a visible camera system.

PubMed

Hu, Shuowen; Goldman, Geoffrey H; Borel-Donohue, Christoph C

2017-01-20

Unmanned aerial vehicles (UAVs) flown by adversaries are an emerging asymmetric threat to homeland security and the military. To help address this threat, we developed and tested a computationally efficient UAV detection algorithm consisting of horizon finding, motion feature extraction, blob analysis, and coherence analysis. We compare the performance of this algorithm against two variants, one using the difference image intensity as the motion features and another using higher-order moments. The proposed algorithm and its variants are tested using field test data of a group 3 UAV acquired with a panoramic video camera in the visible spectrum. The performance of the algorithms was evaluated using receiver operating characteristic curves. The results show that the proposed approach had the best performance compared to the two algorithmic variants.

Handling Different Spatial Resolutions in Image Fusion by Multivariate Curve Resolution-Alternating Least Squares for Incomplete Image Multisets.

PubMed

Piqueras, Sara; Bedia, Carmen; Beleites, Claudia; Krafft, Christoph; Popp, Jürgen; Maeder, Marcel; Tauler, Romà; de Juan, Anna

2018-06-05

Data fusion of different imaging techniques allows a comprehensive description of chemical and biological systems. Yet, joining images acquired with different spectroscopic platforms is complex because of the different sample orientation and image spatial resolution. Whereas matching sample orientation is often solved by performing suitable affine transformations of rotation, translation, and scaling among images, the main difficulty in image fusion is preserving the spatial detail of the highest spatial resolution image during multitechnique image analysis. In this work, a special variant of the unmixing algorithm Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) for incomplete multisets is proposed to provide a solution for this kind of problem. This algorithm allows analyzing simultaneously images collected with different spectroscopic platforms without losing spatial resolution and ensuring spatial coherence among the images treated. The incomplete multiset structure concatenates images of the two platforms at the lowest spatial resolution with the image acquired with the highest spatial resolution. As a result, the constituents of the sample analyzed are defined by a single set of distribution maps, common to all platforms used and with the highest spatial resolution, and their related extended spectral signatures, covering the signals provided by each of the fused techniques. We demonstrate the potential of the new variant of MCR-ALS for multitechnique analysis on three case studies: (i) a model example of MIR and Raman images of pharmaceutical mixture, (ii) FT-IR and Raman images of palatine tonsil tissue, and (iii) mass spectrometry and Raman images of bean tissue.

Surface plasmon holographic microscopy for near-field refractive index detection and thin film mapping

NASA Astrophysics Data System (ADS)

Zhao, Jianlin; Zhang, Jiwei; Dai, Siqing; Di, Jianglei; Xi, Teli

2018-02-01

Surface plasmon microscopy (SPM) is widely applied for label-free detection of changes of refractive index and concentration, as well as mapping thin films in near field. Traditionally, the SPM systems are based on the detection of light intensity or phase changes. Here, we present two kinds of surface plasmon holographic microscopy (SPHM) systems for amplitude- and phase-contrast imaging simultaneously. Through recording off-axis holograms and numerical reconstruction, the complex amplitude distributions of surface plasmon resonance (SPR) images can be obtained. According to the Fresnel's formula, in a prism/ gold/ dielectric structure, the reflection phase shift is uniquely decided by refractive index of the dielectric. By measuring the phase shift difference of the reflected light exploiting prism-coupling SPHM system based on common-path interference configuration, monitoring tiny refractive index variation and imaging biological tissue are performed. Furthermore, to characterize the thin film thickness in near field, we employ a four-layer SPR model in which the third film layer is within the evanescent field. The complex reflection coefficient, including the reflectivity and reflection phase shift, is uniquely decided by the film thickness. By measuring the complex amplitude distributions of the SPR images exploiting objective-coupling SPHM system based on common-path interference configuration, the thickness distributions of thin films are mapped with sub-nanometer resolution theoretically. Owing to its high temporal stability, the recommended SPHMs show great potentials for monitoring tiny refractive index variations, imaging biological tissues and mapping thin films in near field with dynamic, nondestructive and full-field measurement capabilities in chemistry, biomedicine field, etc.

SU-E-T-438: Frameless Cranial Stereotactic Radiosurgery Immobilization Effectiveness Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tseng, T; Green, S; Sheu, R

Purpose: To evaluate immobilization effectiveness of Brainlab frameless mask in cranial stereotactic radiosurgery (SRS). Methods: Two sets of setup images were collected pre-and post-treatment for 24 frameless SRS cases. The pre-treatment images were obtained after applying 2D-2D kV image-guided shifts with patients in treatment position and approved by physicians; the post-treatment images were taken immediately after treatment completion. All cases were treated on a Novalis linac with ExacTrac positioning system and Exact Couch. The two image sets were compared with the correctional shifts measured by ExacTrac 6D auto-fusion. The shift differences were considered patient motion within the frameless mask andmore » were used to evaluate its effectiveness for immobilization. Two-tailed paired t-test was applied for significance comparison. Results: The correctional shifts (mean±STD, median) of pre-and post-treatment images were 0.33±0.27mm, 0.26mm and 0.34±0.27mm, 0.23mm (p=0.740) in lateral direction; 0.32±0.29mm, 0.22mm and 0.48±0.30mm, 0.50mm (p=0.012) in longitudinal direction; 0.31±0.22mm, 0.24mm and 0.33±0.21mm, 0.36mm (p=0.623) in vertical direction. The radial correctional shifts (mean±STD, median) of pre -and post-treatment images were 0.60±0.38mm, 0.45mm and 0.75±0.31mm, 0.66mm (p=0.033). The shift differences (mean±STD, median, maximum) were 0.35±0.28mm, 0.3mm, 1.05mm, 0.34±0.28mm, 0.3mm, 1.00mm, 0.24±0.15mm, 0.21mm, 0.60mm and 0.61±0.32mm, 0.57mm, 1.40mm in lateral, longitudinal, vertical and radial direction, respectively. Two shifts greater than 1 mm (1.06mm and 1.02mm) were acquired from post-treatment images. However, the shift differences were only 0.09 and 0.19mm for these two shifts. Two patients with shift differences greater than 1mm (1.05 and 1.04mm) were observed and didn’t coincide with those two who had post-correctional shifts greater than 1mm. Conclusion: Image-guided SRS allowed us to set up patients with sub-millimeter accuracy relative to simulation position. However, patient motion during treatment could affect treatment accuracy. Our Result shows that Brainlab frameless mask provides reasonable patient immobilization and maintains the mean post-treatment position within sub-millimeter accuracy with some borderline results observed.« less

On-Board Imaging Validation of Optically Guided Stereotactic Radiosurgery Positioning System for Conventionally Fractionated Radiotherapy for Paranasal Sinus and Skull Base Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxim, Peter G.; Loo, Billy W.; Murphy, James D.

2011-11-15

Purpose: To evaluate the positioning accuracy of an optical positioning system for stereotactic radiosurgery in a pilot experience of optically guided, conventionally fractionated, radiotherapy for paranasal sinus and skull base tumors. Methods and Materials: Before each daily radiotherapy session, the positioning of 28 patients was set up using an optical positioning system. After this initial setup, the patients underwent standard on-board imaging that included daily orthogonal kilovoltage images and weekly cone beam computed tomography scans. Daily translational shifts were made after comparing the on-board images with the treatment planning computed tomography scans. These daily translational shifts represented the daily positionalmore » error in the optical tracking system and were recorded during the treatment course. For 13 patients treated with smaller fields, a three-degree of freedom (3DOF) head positioner was used for more accurate setup. Results: The mean positional error for the optically guided system in patients with and without the 3DOF head positioner was 1.4 {+-} 1.1 mm and 3.9 {+-} 1.6 mm, respectively (p <.0001). The mean positional error drifted 0.11 mm/wk upward during the treatment course for patients using the 3DOF head positioner (p = .057). No positional drift was observed in the patients without the 3DOF head positioner. Conclusion: Our initial clinical experience with optically guided head-and-neck fractionated radiotherapy was promising and demonstrated clinical feasibility. The optically guided setup was especially useful when used in conjunction with the 3DOF head positioner and when it was recalibrated to the shifts using the weekly portal images.« less

Range determination for scannerless imaging

DOEpatents

Muguira, Maritza Rosa; Sackos, John Theodore; Bradley, Bart Davis; Nellums, Robert

2000-01-01

A new method of operating a scannerless range imaging system (e.g., a scannerless laser radar) has been developed. This method is designed to compensate for nonlinear effects which appear in many real-world components. The system operates by determining the phase shift of the laser modulation, which is a physical quantity related physically to the path length between the laser source and the detector, for each pixel of an image.

mRuby, a Bright Monomeric Red Fluorescent Protein for Labeling of Subcellular Structures

PubMed Central

Kredel, Simone; Oswald, Franz; Nienhaus, Karin; Deuschle, Karen; Röcker, Carlheinz; Wolff, Michael; Heilker, Ralf; Nienhaus, G. Ulrich; Wiedenmann, Jörg

2009-01-01

A monomeric variant of the red fluorescent protein eqFP611, mRuby, is described. With excitation and emission maxima at 558 nm and 605 nm, respectively, and a large Stokes shift of 47 nm, mRuby appears particularly useful for imaging applications. The protein shows an exceptional resistance to denaturation at pH extremes. Moreover, mRuby is about ten-fold brighter compared to EGFP when being targeted to the endoplasmic reticulum. The engineering process of eqFP611 revealed that the C-terminal tail of the protein acts as a natural peroxisomal targeting signal (PTS). Using an mRuby variant carrying the eqFP611-PTS, we discovered that ordered inheritance of peroxisomes is widespread during mitosis of different mammalian cell types. The ordered partitioning is realized by the formation of peroxisome clusters around the poles of the mitotic spindle and ensures that equal numbers of the organelle are inherited by the daughter cells. The unique spectral properties make mRuby the marker of choice for a multitude of cell biological applications. Moreover, the use of mRuby has allowed novel insights in the biology of organelles responsible for severe human diseases. PMID:19194514

A new Fourier transform based CBIR scheme for mammographic mass classification: a preliminary invariance assessment

NASA Astrophysics Data System (ADS)

Gundreddy, Rohith Reddy; Tan, Maxine; Qui, Yuchen; Zheng, Bin

2015-03-01

The purpose of this study is to develop and test a new content-based image retrieval (CBIR) scheme that enables to achieve higher reproducibility when it is implemented in an interactive computer-aided diagnosis (CAD) system without significantly reducing lesion classification performance. This is a new Fourier transform based CBIR algorithm that determines image similarity of two regions of interest (ROI) based on the difference of average regional image pixel value distribution in two Fourier transform mapped images under comparison. A reference image database involving 227 ROIs depicting the verified soft-tissue breast lesions was used. For each testing ROI, the queried lesion center was systematically shifted from 10 to 50 pixels to simulate inter-user variation of querying suspicious lesion center when using an interactive CAD system. The lesion classification performance and reproducibility as the queried lesion center shift were assessed and compared among the three CBIR schemes based on Fourier transform, mutual information and Pearson correlation. Each CBIR scheme retrieved 10 most similar reference ROIs and computed a likelihood score of the queried ROI depicting a malignant lesion. The experimental results shown that three CBIR schemes yielded very comparable lesion classification performance as measured by the areas under ROC curves with the p-value greater than 0.498. However, the CBIR scheme using Fourier transform yielded the highest invariance to both queried lesion center shift and lesion size change. This study demonstrated the feasibility of improving robustness of the interactive CAD systems by adding a new Fourier transform based image feature to CBIR schemes.

Multiwavelength digital holography with wavelength-multiplexed holograms and arbitrary symmetric phase shifts.

PubMed

Tahara, Tatsuki; Otani, Reo; Omae, Kaito; Gotohda, Takuya; Arai, Yasuhiko; Takaki, Yasuhiro

2017-05-15

We propose multiwavelength in-line digital holography with wavelength-multiplexed phase-shifted holograms and arbitrary symmetric phase shifts. We use phase-shifting interferometry selectively extracting wavelength information to reconstruct multiwavelength object waves separately from wavelength-multiplexed monochromatic images. The proposed technique obtains systems of equations for real and imaginary parts of multiwavelength object waves from the holograms by introducing arbitrary symmetric phase shifts. Then, the technique derives each complex amplitude distribution of each object wave selectively and analytically by solving the two systems of equations. We formulate the algorithm in the case of an arbitrary number of wavelengths and confirm its validity numerically and experimentally in the cases where the number of wavelengths is two and three.

Fucci2a: a bicistronic cell cycle reporter that allows Cre mediated tissue specific expression in mice.

PubMed

Mort, Richard Lester; Ford, Matthew Jonathan; Sakaue-Sawano, Asako; Lindstrom, Nils Olof; Casadio, Angela; Douglas, Adam Thomas; Keighren, Margaret Anne; Hohenstein, Peter; Miyawaki, Atsushi; Jackson, Ian James

2014-01-01

Markers of cell cycle stage allow estimation of cell cycle dynamics in cell culture and during embryonic development. The Fucci system incorporates genetically encoded probes that highlight G1 and S/G2/M phases of the cell cycle allowing live imaging. However the available mouse models that incorporate Fucci are beset by problems with transgene inactivation, varying expression level, lack of conditional potential and/or the need to maintain separate transgenes-there is no transgenic mouse model that solves all these problems. To address these shortfalls we re-engineered the Fucci system to create 2 bicistronic Fucci variants incorporating both probes fused using the Thosea asigna virus 2A (T2A) self cleaving peptide. We characterize these variants in stable 3T3 cell lines. One of the variants (termed Fucci2a) faithfully recapitulated the nuclear localization and cell cycle stage specific florescence of the original Fucci system. We go on to develop a conditional mouse allele (R26Fucci2aR) carefully designed for high, inducible, ubiquitous expression allowing investigation of cell cycle status in single cell lineages within the developing embryo. We demonstrate the utility of R26Fucci2aR for live imaging by using high resolution confocal microscopy of ex vivo lung, kidney and neural crest development. Using our 3T3 system we describe and validate a method to estimate cell cycle times from relatively short time-lapse sequences that we then apply to our neural crest data. The Fucci2a system and the R26Fucci2aR mouse model are compelling new tools for the investigation of cell cycle dynamics in cell culture and during mouse embryonic development.

CT angiography of the renal arteries and veins: normal anatomy and variants.

PubMed

Hazırolan, Tuncay; Öz, Meryem; Türkbey, Barış; Karaosmanoğlu, Ali Devrim; Oğuz, Berna Sayan; Canyiğit, Murat

2011-03-01

Conventional angiography has long been regarded as gold standard imaging modality for evaluation of the renal vasculature. Introduction of multidetector computed tomography (MDCT) angiography had a groundbreaking impact on evaluation of the renal vessels and is gradually replacing conventional angiography as standard imaging. Herein, we review and illustrate the normal and variant anatomy of renal vessels with special emphasis on imaging protocols and reconstruction techniques in MDCT.

A modification of the fusion model for log polar coordinates

NASA Technical Reports Server (NTRS)

Griswold, N. C.; Weiman, Carl F. R.

1990-01-01

The fusion mechanism for application in stereo analysis of range restricted the depth of field and therefore required a shift variant mechanism in the peripheral area to find disparity. Misregistration was prevented by restricting the disparity detection range to a neighborhood spanned by the directional edge detection filters. This transformation was essentially accomplished by a nonuniform resampling of the original image in a horizontal direction. While this is easily implemented for digital processing, the approach does not (in the peripheral vision area) model the log-conformal mapping which is known to occur in the human mechanism. This paper therefore modifies the original fusion concept in the peripheral area to include the polar exponential grid-to-log conformal tesselation. Examples of the fusion process resulting in accurate disparity values are given.

Molecular Imaging for Breast Cancer Using Magnetic Resonance-Guided Positron Emission Mammography and Excitation-Resolved Near-Infrared Fluorescence Imaging

NASA Astrophysics Data System (ADS)

Cho, Jaedu

The aim of this work is to develop novel breast-specific molecular imaging techniques for management of breast cancer. In this dissertation, we describe two novel molecular imaging approaches for breast cancer management. In Part I, we introduce our multimodal molecular imaging approach for breast cancer therapy monitoring using magnetic resonance imaging and positron emission mammography (MR/PEM). We have focused on the therapy monitoring technique for aggressive cancer molecular subtypes, which is challenging due to time constraint. Breast cancer therapy planning relies on a fast and accurate monitoring of functional and anatomical change. We demonstrate a proof-of-concept of sequential dual-modal magnetic resonance and positron emission mammography (MR/PEM) for the cancer therapy monitoring. We have developed dedicated breast coils with breast compression mechanism equipped with MR-compatible PEM detector heads. We have designed a fiducial marker that allows straightforward image registration of data obtained from MRI and PEM. We propose an optimal multimodal imaging procedure for MR/PEM. In Part II, we have focused on the development of a novel intraoperative near-infrared fluorescence imaging system (NIRF) for image-guided breast cancer surgery. Conventional spectrally-resolved NIRF systems are unable to resolve various NIR fluorescence dyes for the following reasons. First, the fluorescence spectra of viable NIR fluorescence dyes are heavily overlapping. Second, conventional emission-resolved NIRF suffers from a trade-off between the fluence rate and the spectral resolution. Third, the multiple scattering in tissue degrades not only the spatial information but also the spectral contents by the red-shift. We develop a wavelength-swept laser-based NIRF system that can resolve the excitation shift of various NIR fluorescence dyes without substantial loss of the fluence rate. A linear ratiometric model is employed to measure the relative shift of the excitation spectrum of a fluorescence dye.

Smart Stylet: The development and use of a bedside external ventricular drain image-guidance system

PubMed Central

Patil, Vaibhav; Gupta, Rajiv; Estépar, Raúl San José; Lacson, Ronilda; Cheung, Arnold; Wong, Judith M.; Popp, A. John; Golby, Alexandra; Ogilvy, Christopher; Vosburgh, Kirby G.

2015-01-01

Background Placement accuracy of ventriculostomy catheters is reported in a wide and variable range. Development of an efficient image-guidance system may improve physician performance and patient safety. Objective We evaluate the prototype of Smart Stylet, a new electromagnetic image-guidance system for use during bedside ventriculostomy. Methods Accuracy of the Smart Stylet system was assessed. System operators were evaluated for their ability to successfully target the ipsilateral frontal horn in a phantom model. Results Target registration error across 15 intracranial targets ranged from 1.3 – 4.6 mm (mean 3.1 mm). Using Smart Stylet guidance, a test operator successfully passed a ventriculostomy catheter to a shifted ipsilateral frontal horn 20/20 (100%) times from the frontal approach in a skull phantom. Without Smart Stylet guidance, the operator was successful 4/10 (40 %) from the right frontal approach and 6/10 (60 %) from the left frontal approach. In a separate experiment, resident operators were successful 2/4 (50%) when targeting the shifted ipsilateral frontal horn with Smart Stylet guidance and 0/4 (0 %) without image-guidance using a skull phantom. Conclusions Smart Stylet may improve the ability to successfully target the ventricles during frontal ventriculostomy. PMID:25662506

Infrared image enhancement using H(infinity) bounds for surveillance applications.

PubMed

Qidwai, Uvais

2008-08-01

In this paper, two algorithms have been presented to enhance the infrared (IR) images. Using the autoregressive moving average model structure and H(infinity) optimal bounds, the image pixels are mapped from the IR pixel space into normal optical image space, thus enhancing the IR image for improved visual quality. Although H(infinity)-based system identification algorithms are very common now, they are not quite suitable for real-time applications owing to their complexity. However, many variants of such algorithms are possible that can overcome this constraint. Two such algorithms have been developed and implemented in this paper. Theoretical and algorithmic results show remarkable enhancement in the acquired images. This will help in enhancing the visual quality of IR images for surveillance applications.

Technical Note: Dosimetric effects of couch position variability on treatment plan quality with an MRI-guided Co-60 radiation therapy machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, Phillip E., E-mail: pechow@mednet.ucla.edu

2016-08-15

Purpose: Magnetic resonance imaging (MRI) guidance in radiation therapy brings real-time imaging and adaptive planning into the treatment vault where it can account for interfraction and intrafraction movement of soft tissue. The only commercially available MRI-guided radiation therapy device is a three-head {sup 60}Co and MRI system with an integrated treatment planning system (TPS). Couch attenuation of the beam of up to 20% is well modeled in the TPS. Variations in the patient’s day-to-day position introduce discrepancies in the actual couch attenuation as modeled in the treatment plan. For this reason, the authors’ institution avoids plans with beams that passmore » through or near the couch edges. This study investigates the effects of differential beam attenuation by the couch due to couch shifts in order to determine whether couch edge avoidance restrictions can be lifted. Couch shifts were simulated using a Monte Carlo treatment planning system and ion chamber measurements performed for validation. Methods: A total of 27 plans from 23 patients were investigated. Couch shifts of 1 and 2 cm were introduced in combinations of lateral and vertical directions to simulate patient position variations giving 16 shifted plans per reference plan. The 1 and 2 cm shifts were based on shifts recorded in 320 treatment fractions. Results: Following TG176 recommendations for measurement methods, couch attenuation measurements agreed with TPS modeled attenuation to within 2.1%. Planning target volume D95 changed less than 1% for 1 and 2 cm couch shifts in only the x-direction and less than 3% for all directions. Conclusions: Dosimetry of all plans tested was robust to couch shifts up to ±2 cm. In general, couch shifts resulted in clinically insignificant dosimetric deviations. It is conceivable that in certain cases with large systematic couch shifts and plans that are particularly sensitive to shifts, dosimetric changes might rise to a clinically significant level.« less

Forward model with space-variant of source size for reconstruction on X-ray radiographic image

NASA Astrophysics Data System (ADS)

Liu, Jin; Liu, Jun; Jing, Yue-feng; Xiao, Bo; Wei, Cai-hua; Guan, Yong-hong; Zhang, Xuan

2018-03-01

The Forward Imaging Technique is a method to solve the inverse problem of density reconstruction in radiographic imaging. In this paper, we introduce the forward projection equation (IFP model) for the radiographic system with areal source blur and detector blur. Our forward projection equation, based on X-ray tracing, is combined with the Constrained Conjugate Gradient method to form a new method for density reconstruction. We demonstrate the effectiveness of the new technique by reconstructing density distributions from simulated and experimental images. We show that for radiographic systems with source sizes larger than the pixel size, the effect of blur on the density reconstruction is reduced through our method and can be controlled within one or two pixels. The method is also suitable for reconstruction of non-homogeneousobjects.

Optical cage generated by azimuthal- and radial-variant vector beams.

PubMed

Man, Zhongsheng; Bai, Zhidong; Li, Jinjian; Zhang, Shuoshuo; Li, Xiaoyu; Zhang, Yuquan; Ge, Xiaolu; Fu, Shenggui

2018-05-01

We propose a method to generate an optical cage using azimuthal- and radial-variant vector beams in a high numerical aperture optical system. A new kind of vector beam that has azimuthal- and radial-variant polarization states is proposed and demonstrated theoretically. Then, an integrated analytical model to calculate the electromagnetic field and Poynting vector distributions of the input azimuthal- and radial-variant vector beams is derived and built based on the vector diffraction theory of Richards and Wolf. From calculations, a full polarization-controlled optical cage is obtained by simply tailoring the radial index of the polarization, the uniformity U of which is up to 0.7748, and the cleanness C is zero. Additionally, a perfect optical cage can be achieved with U=1, and C=0 by introducing an amplitude modulation; its magnetic field and energy flow are also demonstrated in detail. Such optical cages may be helpful in applications such as optical trapping and high-resolution imaging.

High-speed single-pixel digital holography

NASA Astrophysics Data System (ADS)

González, Humberto; Martínez-León, Lluís.; Soldevila, Fernando; Araiza-Esquivel, Ma.; Tajahuerce, Enrique; Lancis, Jesús

2017-06-01

The complete phase and amplitude information of biological specimens can be easily determined by phase-shifting digital holography. Spatial light modulators (SLMs) based on liquid crystal technology, with a frame-rate around 60 Hz, have been employed in digital holography. In contrast, digital micro-mirror devices (DMDs) can reach frame rates up to 22 kHz. A method proposed by Lee to design computer generated holograms (CGHs) permits the use of such binary amplitude modulators as phase-modulation devices. Single-pixel imaging techniques record images by sampling the object with a sequence of micro-structured light patterns and using a simple photodetector. Our group has reported some approaches combining single-pixel imaging and phase-shifting digital holography. In this communication, we review these techniques and present the possibility of a high-speed single-pixel phase-shifting digital holography system with phase-encoded illumination. This system is based on a Mach-Zehnder interferometer, with a DMD acting as the modulator for projecting the sampling patterns on the object and also being used for phase-shifting. The proposed sampling functions are phaseencoded Hadamard patterns generated through a Lee hologram approach. The method allows the recording of the complex amplitude distribution of an object at high speed on account of the high frame rates of the DMD. Reconstruction may take just a few seconds. Besides, the optical setup is envisaged as a true adaptive system, which is able to measure the aberration induced by the optical system in the absence of a sample object, and then to compensate the wavefront in the phasemodulation stage.

Effect of Solvation on Electron Detachment and Excitation Energies of a Green Fluorescent Protein Chromophore Variant.

PubMed

Bose, Samik; Chakrabarty, Suman; Ghosh, Debashree

2016-05-19

Hybrid quantum mechanics/molecular mechanics (QM/MM) is applied to the fluorinated green fluorescent protein (GFP) chromophore (DFHBDI) in its deprotonated form to understand the solvatochromic shifts in its vertical detachment energy (VDE) and vertical excitation energy (VEE). This variant of the GFP chromophore becomes fluorescent in an RNA environment and has a wide range of applications in biomedical and biochemical fields. From microsolvation studies, we benchmark (with respect to full QM) the accuracy of our QM/MM calculations with effective fragment potential (EFP) as the MM method of choice. We show that while the solvatochromic shift in the VEE is minimal (0.1 eV blue shift) and its polarization component is only 0.03 eV, the effect of the solvent on the VDE is quite large (3.85 eV). We also show by accurate calculations on the solvatochromic shift of the VDE that polarization accounts for ∼0.23 eV and therefore cannot be neglected. The effect of the counterions on the VDE of the deprotonated chromophore in solvation is studied in detail, and a charge-smearing scheme is suggested for charged chromophores.

Neuroradiological findings in GM2 gangliosidosis variant B1.

PubMed

Bano, Shahina; Prasad, Akhila; Yadav, Sachchida Nand; Chaudhary, Vikas; Garga, Umesh Chandra

2011-07-01

GM2 gangliosidosis variant B1 is a very rare lysosomal disorder. As per our knowledge, to date, only one article depicting the magnetic resonance imaging (MRI) findings of GM2 gangliosidosis variant B1 is available in the literature. We are the first to describe the neuroradiological findings in an Indian patient diagnosed with GM2 gangliosidosis variant B1.

Fluorescent proteins for quantitative microscopy: important properties and practical evaluation.

PubMed

Shaner, Nathan Christopher

2014-01-01

More than 20 years after their discovery, fluorescent proteins (FPs) continue to be the subject of massive engineering efforts yielding continued improvements. Among these efforts are many aspects that should be of great interest to quantitative imaging users. With new variants frequently introduced into the research community, "tried and true" FPs that have been relied on for many years may now be due for upgrades to more modern variants. However, the dizzying array of FPs now available can make the initial act of narrowing down the potential choices an intimidating prospect. This chapter describes the FP properties that most strongly impact their performance in quantitative imaging experiments, along with their physical origins as they are currently understood. A workflow for evaluating a given FP in the researcher's chosen experimental system (e.g., a specific cell line) is described. © 2014 Elsevier Inc. All rights reserved.

Turboprop: improved PROPELLER imaging.

PubMed

Pipe, James G; Zwart, Nicholas

2006-02-01

A variant of periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) MRI, called turboprop, is introduced. This method employs an oscillating readout gradient during each spin echo of the echo train to collect more lines of data per echo train, which reduces the minimum scan time, motion-related artifact, and specific absorption rate (SAR) while increasing sampling efficiency. It can be applied to conventional fast spin-echo (FSE) imaging; however, this article emphasizes its application in diffusion-weighted imaging (DWI). The method is described and compared with conventional PROPELLER imaging, and clinical images collected with this PROPELLER variant are shown. Copyright 2006 Wiley-Liss, Inc.

Preoperative magnetic resonance and intraoperative ultrasound fusion imaging for real-time neuronavigation in brain tumor surgery.

PubMed

Prada, F; Del Bene, M; Mattei, L; Lodigiani, L; DeBeni, S; Kolev, V; Vetrano, I; Solbiati, L; Sakas, G; DiMeco, F

2015-04-01

Brain shift and tissue deformation during surgery for intracranial lesions are the main actual limitations of neuro-navigation (NN), which currently relies mainly on preoperative imaging. Ultrasound (US), being a real-time imaging modality, is becoming progressively more widespread during neurosurgical procedures, but most neurosurgeons, trained on axial computed tomography (CT) and magnetic resonance imaging (MRI) slices, lack specific US training and have difficulties recognizing anatomic structures with the same confidence as in preoperative imaging. Therefore real-time intraoperative fusion imaging (FI) between preoperative imaging and intraoperative ultrasound (ioUS) for virtual navigation (VN) is highly desirable. We describe our procedure for real-time navigation during surgery for different cerebral lesions. We performed fusion imaging with virtual navigation for patients undergoing surgery for brain lesion removal using an ultrasound-based real-time neuro-navigation system that fuses intraoperative cerebral ultrasound with preoperative MRI and simultaneously displays an MRI slice coplanar to an ioUS image. 58 patients underwent surgery at our institution for intracranial lesion removal with image guidance using a US system equipped with fusion imaging for neuro-navigation. In all cases the initial (external) registration error obtained by the corresponding anatomical landmark procedure was below 2 mm and the craniotomy was correctly placed. The transdural window gave satisfactory US image quality and the lesion was always detectable and measurable on both axes. Brain shift/deformation correction has been successfully employed in 42 cases to restore the co-registration during surgery. The accuracy of ioUS/MRI fusion/overlapping was confirmed intraoperatively under direct visualization of anatomic landmarks and the error was < 3 mm in all cases (100 %). Neuro-navigation using intraoperative US integrated with preoperative MRI is reliable, accurate and user-friendly. Moreover, the adjustments are very helpful in correcting brain shift and tissue distortion. This integrated system allows true real-time feedback during surgery and is less expensive and time-consuming than other intraoperative imaging techniques, offering high precision and orientation. © Georg Thieme Verlag KG Stuttgart · New York.

Utilizing the KCNJ11 Gene Mutations in Spotting Egyptian Patients With Permanent Neonatal Diabetes Who Can Benefit From Treatment Shift.

PubMed

Ahmed, Dina M; Abdel Dayem, Soha M; Abdel Kader, Mona; Khalifa, Rania H; El-Lebedy, Dalia H; Kamel, Solaf A; Shawky, Shereen M

2017-08-01

Neonatal diabetes mellitus (NDM) is a monogenic form of diabetes mellitus. Until now, patients in developing countries who had this condition had been misdiagnosed as having type 1 diabetes mellitus and accordingly directed to erroneous, ineffective, and costly therapeutic regimens. To detect Egyptian patients who harbor pathological variant in the KCNJ11 gene, so that their treatment regimen can be modified as needed to increase its effectiveness. We sequenced KCNJ11 in 17 ethnic Egyptian probands diagnosed with diabetes mellitus before age 2 years. A preliminary case individual harboring a KCNJ11 pathological variant (p.R201H) was identified. The patient was successfully shifted from insulin therapy to sulfonylurea. Four previously identified benign variants, namely, E23K, I337V, L270V, and A190A, were detected in this patient. Implementing the findings of this molecular analysis could have a major clinical and nationwide economic impact on world health, especially in developing countries. © American Society for Clinical Pathology, 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Integrated system for point cloud reconstruction and simulated brain shift validation using tracked surgical microscope

NASA Astrophysics Data System (ADS)

Yang, Xiaochen; Clements, Logan W.; Luo, Ma; Narasimhan, Saramati; Thompson, Reid C.; Dawant, Benoit M.; Miga, Michael I.

2017-03-01

Intra-operative soft tissue deformation, referred to as brain shift, compromises the application of current imageguided surgery (IGS) navigation systems in neurosurgery. A computational model driven by sparse data has been used as a cost effective method to compensate for cortical surface and volumetric displacements. Stereoscopic microscopes and laser range scanners (LRS) are the two most investigated sparse intra-operative imaging modalities for driving these systems. However, integrating these devices in the clinical workflow to facilitate development and evaluation requires developing systems that easily permit data acquisition and processing. In this work we present a mock environment developed to acquire stereo images from a tracked operating microscope and to reconstruct 3D point clouds from these images. A reconstruction error of 1 mm is estimated by using a phantom with a known geometry and independently measured deformation extent. The microscope is tracked via an attached tracking rigid body that facilitates the recording of the position of the microscope via a commercial optical tracking system as it moves during the procedure. Point clouds, reconstructed under different microscope positions, are registered into the same space in order to compute the feature displacements. Using our mock craniotomy device, realistic cortical deformations are generated. Our experimental results report approximately 2mm average displacement error compared with the optical tracking system. These results demonstrate the practicality of using tracked stereoscopic microscope as an alternative to LRS to collect sufficient intraoperative information for brain shift correction.

Generating Artificial Reference Images for Open Loop Correlation Wavefront Sensors

NASA Astrophysics Data System (ADS)

Townson, M. J.; Love, G. D.; Saunter, C. D.

2018-05-01

Shack-Hartmann wavefront sensors for both solar and laser guide star adaptive optics (with elongated spots) need to observe extended objects. Correlation techniques have been successfully employed to measure the wavefront gradient in solar adaptive optics systems and have been proposed for laser guide star systems. In this paper we describe a method for synthesising reference images for correlation Shack-Hartmann wavefront sensors with a larger field of view than individual sub-apertures. We then show how these supersized reference images can increase the performance of correlation wavefront sensors in regimes where large relative shifts are induced between sub-apertures, such as those observed in open-loop wavefront sensors. The technique we describe requires no external knowledge outside of the wavefront-sensor images, making it available as an entirely "software" upgrade to an existing adaptive optics system. For solar adaptive optics we show the supersized reference images extend the magnitude of shifts which can be accurately measured from 12% to 50% of the field of view of a sub-aperture and in laser guide star wavefront sensors the magnitude of centroids that can be accurately measured is increased from 12% to 25% of the total field of view of the sub-aperture.

Galactosidase Alpha p.A143T Variant Fabry Disease May Result in a Phenotype With Multifocal Microvascular Cerebral Involvement at a Young Age.

PubMed

Hauth, Lothar; Kerstens, Jeroen; Yperzeele, Laetitia; Eyskens, François; Parizel, Paul M; Willekens, Barbara

2018-01-01

A 16-year-old male presented with episodic headaches and a brain magnetic resonance imaging (MRI) that showed multifocal punctate to patchy white matter lesions. The diagnosis of Fabry disease (FD) was suggested upon the finding of significantly reduced plasma alpha-galactosidase A activity (0.62 µmol/L or 13% of normal; normal range ≥ 1.65 μmol/L) and genetic investigation confirmed the presence of a hemizygous missense variant in the galactosidase alpha (GLA) gene (p.A143T). Baseline assessment of other systemic involvement showed only a discrete proteinuria. FD is a rare lysosomal storage disorder. Genetic screening studies have revealed over 600 variants in the GLA gene. The p.A143T variant is a genetic variant of unknown significance, with its associated phenotype ranging from classical FD to healthy unaffected patients. Some authors, however, deem this variant non-pathogenic. We describe the case of a 16-year-old male with multifocal white matter lesions on brain MRI, who was diagnosed with FD and carried this genetic variant. The causative p.A143T mutation can be associated with a more severe subclinical phenotype than has been reported to date. Furthermore, a diagnosis of FD should be considered when finding asymptomatic cerebral white matter lesions in a young patient.

Photoconversion in orange and red fluorescent proteins

PubMed Central

Kremers, Gert-Jan; Hazelwood, Kristin L.; Murphy, Christopher S.; Davidson, Michael W.; Piston, David W.

2009-01-01

We report that photoconversion is fairly common among orange and red fluorescent proteins, as a screen of 12 variants yielded 8 that exhibit photoconversion. Specifically, three red fluorescent proteins can be switched into a green state, and two orange variants can be photoconverted to the far red. The orange highlighters are ideal for dual-probe highlighter applications, and they exhibit the most red-shifted excitation of all fluorescent protein described to date. PMID:19363494

Magnetic quadrupoles lens for hot spot proton imaging in inertial confinement fusion

NASA Astrophysics Data System (ADS)

Teng, J.; Gu, Y. Q.; Chen, J.; Zhu, B.; Zhang, B.; Zhang, T. K.; Tan, F.; Hong, W.; Zhang, B. H.; Wang, X. Q.

2016-08-01

Imaging of DD-produced protons from an implosion hot spot region by miniature permanent magnetic quadrupole (PMQ) lens is proposed. Corresponding object-image relation is deduced and an adjust method for this imaging system is discussed. Ideal point-to-point imaging demands a monoenergetic proton source; nevertheless, we proved that the blur of image induced by proton energy spread is a second order effect therefore controllable. A proton imaging system based on miniature PMQ lens is designed for 2.8 MeV DD-protons and the adjust method in case of proton energy shift is proposed. The spatial resolution of this system is better than 10 μm when proton yield is above 109 and the spectra width is within 10%.

Data-Driven Multiresolution Camera Using the Foveal Adaptive Pyramid

PubMed Central

González, Martin; Sánchez-Pedraza, Antonio; Marfil, Rebeca; Rodríguez, Juan A.; Bandera, Antonio

2016-01-01

There exist image processing applications, such as tracking or pattern recognition, that are not necessarily precise enough to maintain the same resolution across the whole image sensor. In fact, they must only keep it as high as possible in a relatively small region, but covering a wide field of view. This is the aim of foveal vision systems. Briefly, they propose to sense a large field of view at a spatially-variant resolution: one relatively small region, the fovea, is mapped at a high resolution, while the rest of the image is captured at a lower resolution. In these systems, this fovea must be moved, from one region of interest to another one, to scan a visual scene. It is interesting that the part of the scene that is covered by the fovea should not be merely spatial, but closely related to perceptual objects. Segmentation and attention are then intimately tied together: while the segmentation process is responsible for extracting perceptively-coherent entities from the scene (proto-objects), attention can guide segmentation. From this loop, the concept of foveal attention arises. This work proposes a hardware system for mapping a uniformly-sampled sensor to a space-variant one. Furthermore, this mapping is tied with a software-based, foveal attention mechanism that takes as input the stream of generated foveal images. The whole hardware/software architecture has been designed to be embedded within an all programmable system on chip (AP SoC). Our results show the flexibility of the data port for exchanging information between the mapping and attention parts of the architecture and the good performance rates of the mapping procedure. Experimental evaluation also demonstrates that the segmentation method and the attention model provide results comparable to other more computationally-expensive algorithms. PMID:27898029

Data-Driven Multiresolution Camera Using the Foveal Adaptive Pyramid.

PubMed

González, Martin; Sánchez-Pedraza, Antonio; Marfil, Rebeca; Rodríguez, Juan A; Bandera, Antonio

2016-11-26

There exist image processing applications, such as tracking or pattern recognition, that are not necessarily precise enough to maintain the same resolution across the whole image sensor. In fact, they must only keep it as high as possible in a relatively small region, but covering a wide field of view. This is the aim of foveal vision systems. Briefly, they propose to sense a large field of view at a spatially-variant resolution: one relatively small region, the fovea, is mapped at a high resolution, while the rest of the image is captured at a lower resolution. In these systems, this fovea must be moved, from one region of interest to another one, to scan a visual scene. It is interesting that the part of the scene that is covered by the fovea should not be merely spatial, but closely related to perceptual objects. Segmentation and attention are then intimately tied together: while the segmentation process is responsible for extracting perceptively-coherent entities from the scene (proto-objects), attention can guide segmentation. From this loop, the concept of foveal attention arises. This work proposes a hardware system for mapping a uniformly-sampled sensor to a space-variant one. Furthermore, this mapping is tied with a software-based, foveal attention mechanism that takes as input the stream of generated foveal images. The whole hardware/software architecture has been designed to be embedded within an all programmable system on chip (AP SoC). Our results show the flexibility of the data port for exchanging information between the mapping and attention parts of the architecture and the good performance rates of the mapping procedure. Experimental evaluation also demonstrates that the segmentation method and the attention model provide results comparable to other more computationally-expensive algorithms.

A Variational Approach to the Denoising of Images Based on Different Variants of the TV-Regularization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bildhauer, Michael, E-mail: bibi@math.uni-sb.de; Fuchs, Martin, E-mail: fuchs@math.uni-sb.de

2012-12-15

We discuss several variants of the TV-regularization model used in image recovery. The proposed alternatives are either of nearly linear growth or even of linear growth, but with some weak ellipticity properties. The main feature of the paper is the investigation of the analytic properties of the corresponding solutions.

Hybrid UV Imager Containing Face-Up AlGaN/GaN Photodiodes

NASA Technical Reports Server (NTRS)

Zheng, Xinyu; Pain, Bedabrata

2005-01-01

A proposed hybrid ultraviolet (UV) image sensor would comprise a planar membrane array of face-up AlGaN/GaN photodiodes integrated with a complementary metal oxide/semiconductor (CMOS) readout-circuit chip. Each pixel in the hybrid image sensor would contain a UV photodiode on the AlGaN/GaN membrane, metal oxide/semiconductor field-effect transistor (MOSFET) readout circuitry on the CMOS chip underneath the photodiode, and a metal via connection between the photodiode and the readout circuitry (see figure). The proposed sensor design would offer all the advantages of comparable prior CMOS active-pixel sensors and AlGaN UV detectors while overcoming some of the limitations of prior (AlGaN/sapphire)/CMOS hybrid image sensors that have been designed and fabricated according to the methodology of flip-chip integration. AlGaN is a nearly ideal UV-detector material because its bandgap is wide and adjustable and it offers the potential to attain extremely low dark current. Integration of AlGaN with CMOS is necessary because at present there are no practical means of realizing readout circuitry in the AlGaN/GaN material system, whereas the means of realizing readout circuitry in CMOS are well established. In one variant of the flip-chip approach to integration, an AlGaN chip on a sapphire substrate is inverted (flipped) and then bump-bonded to a CMOS readout circuit chip; this variant results in poor quantum efficiency. In another variant of the flip-chip approach, an AlGaN chip on a crystalline AlN substrate would be bonded to a CMOS readout circuit chip; this variant is expected to result in narrow spectral response, which would be undesirable in many applications. Two other major disadvantages of flip-chip integration are large pixel size (a consequence of the need to devote sufficient area to each bump bond) and severe restriction on the photodetector structure. The membrane array of AlGaN/GaN photodiodes and the CMOS readout circuit for the proposed image sensor would be fabricated separately.

Deciphering and Imaging Pathogenesis and Cording of Mycobacterium abscessus in Zebrafish Embryos

PubMed Central

Bernut, Audrey; Dupont, Christian; Sahuquet, Alain; Herrmann, Jean-Louis; Lutfalla, Georges; Kremer, Laurent

2015-01-01

Zebrafish (Danio rerio) embryos are increasingly used as an infection model to study the function of the vertebrate innate immune system in host-pathogen interactions. The ease of obtaining large numbers of embryos, their accessibility due to external development, their optical transparency as well as the availability of a wide panoply of genetic/immunological tools and transgenic reporter line collections, contribute to the versatility of this model. In this respect, the present manuscript describes the use of zebrafish as an in vivo model system to investigate the chronology of Mycobacterium abscessus infection. This human pathogen can exist either as smooth (S) or rough (R) variants, depending on cell wall composition, and their respective virulence can be imaged and compared in zebrafish embryos and larvae. Micro-injection of either S or R fluorescent variants directly in the blood circulation via the caudal vein, leads to chronic or acute/lethal infections, respectively. This biological system allows high resolution visualization and analysis of the role of mycobacterial cording in promoting abscess formation. In addition, the use of fluorescent bacteria along with transgenic zebrafish lines harbouring fluorescent macrophages produces a unique opportunity for multi-color imaging of the host-pathogen interactions. This article describes detailed protocols for the preparation of homogenous M. abscessus inoculum and for intravenous injection of zebrafish embryos for subsequent fluorescence imaging of the interaction with macrophages. These techniques open the avenue to future investigations involving mutants defective in cord formation and are dedicated to understand how this impacts on M. abscessus pathogenicity in a whole vertebrate. PMID:26382225

Rates of Amyloid Imaging Positivity in Patients With Primary Progressive Aphasia.

PubMed

Santos-Santos, Miguel A; Rabinovici, Gil D; Iaccarino, Leonardo; Ayakta, Nagehan; Tammewar, Gautam; Lobach, Iryna; Henry, Maya L; Hubbard, Isabel; Mandelli, Maria Luisa; Spinelli, Edoardo; Miller, Zachary A; Pressman, Peter S; O'Neil, James P; Ghosh, Pia; Lazaris, Andreas; Meyer, Marita; Watson, Christa; Yoon, Soo Jin; Rosen, Howard J; Grinberg, Lea; Seeley, William W; Miller, Bruce L; Jagust, William J; Gorno-Tempini, Maria Luisa

2018-03-01

The ability to predict the pathology underlying different neurodegenerative syndromes is of critical importance owing to the advent of molecule-specific therapies. To determine the rates of positron emission tomography (PET) amyloid positivity in the main clinical variants of primary progressive aphasia (PPA). This prospective clinical-pathologic case series was conducted at a tertiary research clinic specialized in cognitive disorders. Patients were evaluated as part of a prospective, longitudinal research study between January 2002 and December 2015. Inclusion criteria included clinical diagnosis of PPA; availability of complete speech, language, and cognitive testing; magnetic resonance imaging performed within 6 months of the cognitive evaluation; and PET carbon 11-labeled Pittsburgh Compound-B or florbetapir F 18 brain scan results. Of 109 patients referred for evaluation of language symptoms who underwent amyloid brain imaging, 3 were excluded because of incomplete language evaluations, 5 for absence of significant aphasia, and 12 for presenting with significant initial symptoms outside of the language domain, leaving a cohort of 89 patients with PPA. Clinical, cognitive, neuroimaging, and pathology results. Twenty-eight cases were classified as imaging-supported semantic variant PPA (11 women [39.3%]; mean [SD] age, 64 [7] years), 31 nonfluent/agrammatic variant PPA (22 women [71.0%]; mean [SD] age, 68 [7] years), 26 logopenic variant PPA (17 women [65.4%]; mean [SD] age, 63 [8] years), and 4 mixed PPA cases. Twenty-four of 28 patients with semantic variant PPA (86%) and 28 of 31 patients with nonfluent/agrammatic variant PPA (90%) had negative amyloid PET scan results, while 25 of 26 patients with logopenic variant PPA (96%) and 3 of 4 mixed PPA cases (75%) had positive scan results. The amyloid positive semantic variant PPA and nonfluent/agrammatic variant PPA cases with available autopsy data (2 of 4 and 2 of 3, respectively) all had a primary frontotemporal lobar degeneration and secondary Alzheimer disease pathologic diagnoses, whereas autopsy of 2 patients with amyloid PET-positive logopenic variant PPA confirmed Alzheimer disease. One mixed PPA patient with a negative amyloid PET scan had Pick disease at autopsy. Primary progressive aphasia variant diagnosis according to the current classification scheme is associated with Alzheimer disease biomarker status, with the logopenic variant being associated with carbon 11-labeled Pittsburgh Compound-B positivity in more than 95% of cases. Furthermore, in the presence of a clinical syndrome highly predictive of frontotemporal lobar degeneration pathology, biomarker positivity for Alzheimer disease may be associated more with mixed pathology rather than primary Alzheimer disease.

Time-domain Surveys and Data Shift: Case Study at the intermediate Palomar Transient Factory

NASA Astrophysics Data System (ADS)

Rebbapragada, Umaa; Bue, Brian; Wozniak, Przemyslaw R.

2015-01-01

Next generation time-domain surveys are susceptible to the problem of data shift that is caused by upgrades to data processing pipelines and instruments. Data shift degrades the performance of automated machine learning classifiers that vet detections and classify source types because fundamental assumptions are violated when classifiers are built in one data regime but are deployed on data from another. This issue is not currently discussed within the astronomical community, but will be increasingly pressing over the next decade with the advent of new time domain surveys.We look at the problem of data shift that was caused by a data pipeline upgrade when the intermediate Palomar Transient Factory (iPTF) succeeded the Palomar Transient Factory (PTF) in January 2013. iPTF relies upon machine-learned Real-Bogus classifiers to vet sources extracted from subtracted images on a scale of zero to one where zero indicates a bogus (image artifact) and one indicates a real astronomical transient, with the overwhelming majority of candidates are scored as bogus. An effective Real-Bogus system filters all but the most promising candidates, which are presented to human scanners who make decisions about triggering follow up assets.The Real-Bogus systems currently in operation at iPTF (RB4 and RB5) solve the data shift problem. The statistical models of RB4 and RB5 were built from the ground up using examples from iPTF alone, whereas an older system, RB2, was built using PTF data, but was deployed after iPTF launched. We discuss the machine learning assumptions that are violated when a system is trained on one domain (PTF) but deployed on another (iPTF) that experiences data shift. We provide illustrative examples of data parameters and statistics that experienced shift. Finally, we show results comparing the three systems in operation, demonstrating that systems that solve domain shift (RB4 and RB5) are superior to those that don't (RB2).Research described in this abstract was carried out at the Jet Propulsion Laboratory under contract with the National Aeronautics and Space Administration. US Government Support Acknowledged.

Positioning accuracy in a registration-free CT-based navigation system

NASA Astrophysics Data System (ADS)

Brandenberger, D.; Birkfellner, W.; Baumann, B.; Messmer, P.; Huegli, R. W.; Regazzoni, P.; Jacob, A. L.

2007-12-01

In order to maintain overall navigation accuracy established by a calibration procedure in our CT-based registration-free navigation system, the CT scanner has to repeatedly generate identical volume images of a target at the same coordinates. We tested the positioning accuracy of the prototype of an advanced workplace for image-guided surgery (AWIGS) which features an operating table capable of direct patient transfer into a CT scanner. Volume images (N = 154) of a specialized phantom were analysed for translational shifting after various table translations. Variables included added weight and phantom position on the table. The navigation system's calibration accuracy was determined (bias 2.1 mm, precision ± 0.7 mm, N = 12). In repeated use, a bias of 3.0 mm and a precision of ± 0.9 mm (N = 10) were maintainable. Instances of translational image shifting were related to the table-to-CT scanner docking mechanism. A distance scaling error when altering the table's height was detected. Initial prototype problems visible in our study causing systematic errors were resolved by repeated system calibrations between interventions. We conclude that the accuracy achieved is sufficient for a wide range of clinical applications in surgery and interventional radiology.

Imaging the Glenoid Labrum and Labral Tears.

PubMed

De Coninck, Tineke; Ngai, Steven S; Tafur, Monica; Chung, Christine B

2016-10-01

The shoulder joint is the most unstable articulation in the entire human body. While this certainly introduces vulnerability to injury, it also confers the advantage of broad range of motion. There are many elements that work in combination to offset the inherent instability of the glenohumeral joint, but the glenoid labrum is perhaps related most often. Broadly, clinical unidirectional instability can be subdivided into anterior and posterior instability, which usually raise concern for anteroinferior and posteroinferior labral lesions, respectively. In the special case of superior labral damage, potential dislocation is blocked by structures that include the acromion; hence, while damage elsewhere commonly manifests as clinical instability, damage to the superior labrum is often described by the term microinstability. In this particular case, one of the radiologist's main concerns should be classic superior labral anteroposterior lesions. The glenoid labrum is also subject to a wide range of normal variants that can mimic labral tears. Knowledge of these variants is central to interpreting an imaging study of the labrum because misdiagnosis of labral variants as tears can lead to superfluous surgical procedures and decreased shoulder mobility. This article reviews labral anatomy and normal labral variants, describes their imaging features, and discusses how to discriminate normal variants from labral tears. Specific labral pathologic lesions are described per labral quadrant (anteroinferior, posteroinferior, and superior), and imaging features are described in detail. Online supplemental material is available for this article. © RSNA, 2016.

Pan-neuronal calcium imaging with cellular resolution in freely swimming zebrafish.

PubMed

Kim, Dal Hyung; Kim, Jungsoo; Marques, João C; Grama, Abhinav; Hildebrand, David G C; Gu, Wenchao; Li, Jennifer M; Robson, Drew N

2017-11-01

Calcium imaging with cellular resolution typically requires an animal to be tethered under a microscope, which substantially restricts the range of behaviors that can be studied. To expand the behavioral repertoire amenable to imaging, we have developed a tracking microscope that enables whole-brain calcium imaging with cellular resolution in freely swimming larval zebrafish. This microscope uses infrared imaging to track a target animal in a behavior arena. On the basis of the predicted trajectory of the animal, we applied optimal control theory to a motorized stage system to cancel brain motion in three dimensions. We combined this motion-cancellation system with differential illumination focal filtering, a variant of HiLo microscopy, which enabled us to image the brain of a freely swimming larval zebrafish for more than an hour. This work expands the repertoire of natural behaviors that can be studied with cellular-resolution calcium imaging to potentially include spatial navigation, social behavior, feeding and reward.

Shot noise-limited Cramér-Rao bound and algorithmic sensitivity for wavelength shifting interferometry

NASA Astrophysics Data System (ADS)

Chen, Shichao; Zhu, Yizheng

2017-02-01

Sensitivity is a critical index to measure the temporal fluctuation of the retrieved optical pathlength in quantitative phase imaging system. However, an accurate and comprehensive analysis for sensitivity evaluation is still lacking in current literature. In particular, previous theoretical studies for fundamental sensitivity based on Gaussian noise models are not applicable to modern cameras and detectors, which are dominated by shot noise. In this paper, we derive two shot noiselimited theoretical sensitivities, Cramér-Rao bound and algorithmic sensitivity for wavelength shifting interferometry, which is a major category of on-axis interferometry techniques in quantitative phase imaging. Based on the derivations, we show that the shot noise-limited model permits accurate estimation of theoretical sensitivities directly from measured data. These results can provide important insights into fundamental constraints in system performance and can be used to guide system design and optimization. The same concepts can be generalized to other quantitative phase imaging techniques as well.

An investigation of care-based vs. rule-based morality in frontotemporal dementia, Alzheimer's disease, and healthy controls.

PubMed

Carr, Andrew R; Paholpak, Pongsatorn; Daianu, Madelaine; Fong, Sylvia S; Mather, Michelle; Jimenez, Elvira E; Thompson, Paul; Mendez, Mario F

2015-11-01

Behavioral changes in dementia, especially behavioral variant frontotemporal dementia (bvFTD), may result in alterations in moral reasoning. Investigators have not clarified whether these alterations reflect differential impairment of care-based vs. rule-based moral behavior. This study investigated 18 bvFTD patients, 22 early onset Alzheimer's disease (eAD) patients, and 20 healthy age-matched controls on care-based and rule-based items from the Moral Behavioral Inventory and the Social Norms Questionnaire, neuropsychological measures, and magnetic resonance imaging (MRI) regions of interest. There were significant group differences with the bvFTD patients rating care-based morality transgressions less severely than the eAD group and rule-based moral behavioral transgressions more severely than controls. Across groups, higher care-based morality ratings correlated with phonemic fluency on neuropsychological tests, whereas higher rule-based morality ratings correlated with increased difficulty set-shifting and learning new rules to tasks. On neuroimaging, severe care-based reasoning correlated with cortical volume in right anterior temporal lobe, and rule-based reasoning correlated with decreased cortical volume in the right orbitofrontal cortex. Together, these findings suggest that frontotemporal disease decreases care-based morality and facilitates rule-based morality possibly from disturbed contextual abstraction and set-shifting. Future research can examine whether frontal lobe disorders and bvFTD result in a shift from empathic morality to the strong adherence to conventional rules. Published by Elsevier Ltd.

An Investigation of Care-Based vs. Rule-Based Morality in Frontotemporal Dementia, Alzheimer’s Disease, and Healthy Controls

PubMed Central

Carr, Andrew R.; Paholpak, Pongsatorn; Daianu, Madelaine; Fong, Sylvia S.; Mather, Michelle; Jimenez, Elvira E.; Thompson, Paul; Mendez, Mario F.

2015-01-01

Behavioral changes in dementia, especially behavioral variant frontotemporal dementia (bvFTD), may result in alterations in moral reasoning. Investigators have not clarified whether these alterations reflect differential impairment of care-based vs. rule-based moral behavior. This study investigated 18 bvFTD patients, 22 early onset Alzheimer’s disease (eAD) patients, and 20 healthy age-matched controls on care-based and rule-based items from the Moral Behavioral Inventory and the Social Norms Questionnaire, neuropsychological measures, and magnetic resonance imaging (MRI) regions of interest. There were significant group differences with the bvFTD patients rating care-based morality transgressions less severely than the eAD group and rule-based moral behavioral transgressions more severely than controls. Across groups, higher care-based morality ratings correlated with phonemic fluency on neuropsychological tests, whereas higher rule-based morality ratings correlated with increased difficulty set-shifting and learning new rules to tasks. On neuroimaging, severe care-based reasoning correlated with cortical volume in right anterior temporal lobe, and rule-based reasoning correlated with decreased cortical volume in the right orbitofrontal cortex. Together, these findings suggest that frontotemporal disease decreases care-based morality and facilitates rule-based morality possibly from disturbed contextual abstraction and set-shifting. Future research can examine whether frontal lobe disorders and bvFTD result in a shift from empathic morality to the strong adherence to conventional rules. PMID:26432341

Denoising of polychromatic CT images based on their own noise properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Ji Hye; Chang, Yongjin; Ra, Jong Beom, E-mail: jbra@kaist.ac.kr

Purpose: Because of high diagnostic accuracy and fast scan time, computed tomography (CT) has been widely used in various clinical applications. Since the CT scan introduces radiation exposure to patients, however, dose reduction has recently been recognized as an important issue in CT imaging. However, low-dose CT causes an increase of noise in the image and thereby deteriorates the accuracy of diagnosis. In this paper, the authors develop an efficient denoising algorithm for low-dose CT images obtained using a polychromatic x-ray source. The algorithm is based on two steps: (i) estimation of space variant noise statistics, which are uniquely determinedmore » according to the system geometry and scanned object, and (ii) subsequent novel conversion of the estimated noise to Gaussian noise so that an existing high performance Gaussian noise filtering algorithm can be directly applied to CT images with non-Gaussian noise. Methods: For efficient polychromatic CT image denoising, the authors first reconstruct an image with the iterative maximum-likelihood polychromatic algorithm for CT to alleviate the beam-hardening problem. We then estimate the space-variant noise variance distribution on the image domain. Since there are many high performance denoising algorithms available for the Gaussian noise, image denoising can become much more efficient if they can be used. Hence, the authors propose a novel conversion scheme to transform the estimated space-variant noise to near Gaussian noise. In the suggested scheme, the authors first convert the image so that its mean and variance can have a linear relationship, and then produce a Gaussian image via variance stabilizing transform. The authors then apply a block matching 4D algorithm that is optimized for noise reduction of the Gaussian image, and reconvert the result to obtain a final denoised image. To examine the performance of the proposed method, an XCAT phantom simulation and a physical phantom experiment were conducted. Results: Both simulation and experimental results show that, unlike the existing denoising algorithms, the proposed algorithm can effectively reduce the noise over the whole region of CT images while preventing degradation of image resolution. Conclusions: To effectively denoise polychromatic low-dose CT images, a novel denoising algorithm is proposed. Because this algorithm is based on the noise statistics of a reconstructed polychromatic CT image, the spatially varying noise on the image is effectively reduced so that the denoised image will have homogeneous quality over the image domain. Through a simulation and a real experiment, it is verified that the proposed algorithm can deliver considerably better performance compared to the existing denoising algorithms.« less

Spatial-heterodyne interferometry for transmission (SHIFT) measurements

DOEpatents

Bingham, Philip R.; Hanson, Gregory R.; Tobin, Ken W.

2006-10-10

Systems and methods are described for spatial-heterodyne interferometry for transmission (SHIFT) measurements. A method includes digitally recording a spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis using a reference beam, and an object beam that is transmitted through an object that is at least partially translucent; Fourier analyzing the digitally recorded spatially-heterodyned hologram, by shifting an original origin of the digitally recorded spatially-heterodyned hologram to sit on top of a spatial-heterodyne carrier frequency defined by an angle between the reference beam and the object beam, to define an analyzed image; digitally filtering the analyzed image to cut off signals around the original origin to define a result; and performing an inverse Fourier transform on the result.

Ankle fracture spur sign is pathognomonic for a variant ankle fracture.

PubMed

Hinds, Richard M; Garner, Matthew R; Lazaro, Lionel E; Warner, Stephen J; Loftus, Michael L; Birnbaum, Jacqueline F; Burket, Jayme C; Lorich, Dean G

2015-02-01

The hyperplantarflexion variant ankle fracture is composed of a posterior tibial lip fracture with posterolateral and posteromedial fracture fragments separated by a vertical fracture line. This infrequently reported injury pattern often includes an associated "spur sign" or double cortical density at the inferomedial tibial metaphysis. The objective of this study was to quantitatively establish the association of the ankle fracture spur sign with the hyperplantarflexion variant ankle fracture. Our clinical database of operative ankle fractures was retrospectively reviewed for the incidence of hyperplantarflexion variant and nonvariant ankle fractures as determined by assessment of injury radiographs, preoperative advanced imaging, and intraoperative observation. Injury radiographs were then evaluated for the presence of the spur sign, and association between the spur sign and variant fractures was analyzed. The incidence of the hyperplantarflexion variant fracture among all ankle fractures was 6.7% (43/640). The spur sign was present in 79% (34/43) of variant fractures and absent in all nonvariant fractures, conferring a specificity of 100% in identifying variant fractures. Positive predictive value and negative predictive value were 100% and 99%, respectively. The ankle fracture spur sign was pathognomonic for the hyperplantarflexion variant ankle fracture. It is important to identify variant fractures preoperatively as patient positioning, operative approach, and fixation construct of variant fractures often differ from those employed for osteosynthesis of nonvariant fractures. Identification of the spur sign should prompt acquisition of advanced imaging to formulate an appropriate operative plan to address the variant fracture pattern. Level III, retrospective comparative study. © The Author(s) 2014.

Pepino mosaic virus genotype shift in North America and development of a loop-mediated isothermal amplification for rapid genotype identification

PubMed Central

2013-01-01

Background Pepino mosaic, once an emerging disease a decade ago, has become endemic on greenhouse tomatoes worldwide in recent years. Three distinct genotypes of Pepino mosaic virus (PepMV), including EU, US1 and CH2 have been recognized. Our earlier study conducted in 2006–2007 demonstrated a predominant EU genotype in Canada and United States. The objective of the present study was to monitor the dynamic of PepMV genetic composition and its current status in North America. Results Through yearly monitoring efforts in 2009–2012, we detected a dramatic shift in the prevalent genotype of PepMV from the genotype EU to CH2 in North America since early 2010, with another shift from CH2 to US1 occurring in Mexico only two years later. Through genetic diversity analysis using the coat protein gene, such genotype shifting of PepMV in North America was linked to the positive identification of similar sequence variants in two different commercial tomato seed sources used for scion and rootstock, respectively. To allow for a quick identification, a reverse transcription loop-mediated isothermal amplification (RT-LAMP) system was developed and demonstrated to achieve a rapid identification for each of the three genotypes of PepMV, EU, US1 and CH2. Conclusion Through systemic yearly monitoring and genetic diversity analysis, we identified a linkage between the field epidemic isolates and those from commercial tomato seed lots as the likely sources of initial PepMV inoculum that resulted in genetic shifting as observed on greenhouse tomatoes in North America. Application of the genotype-specific RT-LAMP system would allow growers to efficiently determine the genetic diversity on their crops. PMID:23587202

Content based image retrieval using local binary pattern operator and data mining techniques.

PubMed

Vatamanu, Oana Astrid; Frandeş, Mirela; Lungeanu, Diana; Mihalaş, Gheorghe-Ioan

2015-01-01

Content based image retrieval (CBIR) concerns the retrieval of similar images from image databases, using feature vectors extracted from images. These feature vectors globally define the visual content present in an image, defined by e.g., texture, colour, shape, and spatial relations between vectors. Herein, we propose the definition of feature vectors using the Local Binary Pattern (LBP) operator. A study was performed in order to determine the optimum LBP variant for the general definition of image feature vectors. The chosen LBP variant is then subsequently used to build an ultrasound image database, and a database with images obtained from Wireless Capsule Endoscopy. The image indexing process is optimized using data clustering techniques for images belonging to the same class. Finally, the proposed indexing method is compared to the classical indexing technique, which is nowadays widely used.

Imaging genetics approach to predict progression of Parkinson's diseases.

PubMed

Mansu Kim; Seong-Jin Son; Hyunjin Park

2017-07-01

Imaging genetics is a tool to extract genetic variants associated with both clinical phenotypes and imaging information. The approach can extract additional genetic variants compared to conventional approaches to better investigate various diseased conditions. Here, we applied imaging genetics to study Parkinson's disease (PD). We aimed to extract significant features derived from imaging genetics and neuroimaging. We built a regression model based on extracted significant features combining genetics and neuroimaging to better predict clinical scores of PD progression (i.e. MDS-UPDRS). Our model yielded high correlation (r = 0.697, p <; 0.001) and low root mean squared error (8.36) between predicted and actual MDS-UPDRS scores. Neuroimaging (from 123 I-Ioflupane SPECT) predictors of regression model were computed from independent component analysis approach. Genetic features were computed using image genetics approach based on identified neuroimaging features as intermediate phenotypes. Joint modeling of neuroimaging and genetics could provide complementary information and thus have the potential to provide further insight into the pathophysiology of PD. Our model included newly found neuroimaging features and genetic variants which need further investigation.

Consequences of "going digital" for pathology professionals - entering the cloud.

PubMed

Laurinavicius, Arvydas; Raslavicus, Paul

2012-01-01

New opportunities and the adoption of digital technologies will transform the way pathology professionals and services work. Many areas of our daily life as well as medical professions have experienced this change already which has resulted in a paradigm shift in many activities. Pathology is an image-based discipline, therefore, arrival of digital imaging into this domain promises major shift in our work and required mentality. Recognizing the physical and digital duality of the pathology workflow, we can prepare for the imminent increase of the digital component, synergize and enjoy its benefits. Development of a new generation of laboratory information systems along with seamless integration of digital imaging, decision-support, and knowledge databases will enable pathologists to work in a distributed environment. The paradigm of "cloud pathology" is proposed as an ultimate vision of digital pathology workstations plugged into the integrated multidisciplinary patient care systems.

Extrinsic Tryptophans as NMR Probes of Allosteric Coupling in Membrane Proteins: Application to the A2A Adenosine Receptor.

PubMed

Eddy, Matthew T; Gao, Zhan-Guo; Mannes, Philip; Patel, Nilkanth; Jacobson, Kenneth A; Katritch, Vsevolod; Stevens, Raymond C; Wüthrich, Kurt

2018-06-20

Tryptophan indole 15 N- 1 H signals are well separated in nuclear magnetic resonance (NMR) spectra of proteins. Assignment of the indole 15 N- 1 H signals therefore enables one to obtain site-specific information on complex proteins in supramacromolecular systems, even when extensive assignment of backbone 15 N- 1 H resonances is challenging. Here we exploit the unique indole 15 N- 1 H chemical shift by introducing extrinsic tryptophan reporter residues at judiciously chosen locations in a membrane protein for increased coverage of structure and function by NMR. We demonstrate this approach with three variants of the human A 2A adenosine receptor (A 2A AR), a class A G protein-coupled receptor, each containing a single extrinsic tryptophan near the receptor intracellular surface, in helix V, VI, or VII, respectively. We show that the native A 2A AR global protein fold and ligand binding activity are preserved in these A 2A AR variants. The indole 15 N- 1 H signals from the extrinsic tryptophan reporter residues show different responses to variable efficacy of drugs bound to the receptor orthosteric cavity, and the indole 15 N- 1 H chemical shift of the tryptophan introduced at the intracellular end of helix VI is sensitive to conformational changes resulting from interactions with a polypeptide from the carboxy terminus of the Gα S intracellular partner protein. Introducing extrinsic tryptophans into proteins in complex supramolecular systems thus opens new avenues for NMR investigations in solution.

Specific insertions of zinc finger domains into Gag-Pol yield engineered retroviral vectors with selective integration properties

PubMed Central

Lim, Kwang-il; Klimczak, Ryan; Yu, Julie H.; Schaffer, David V.

2010-01-01

Retroviral vectors offer benefits of efficient delivery and stable gene expression; however, their clinical use raises the concerns of insertional mutagenesis and potential oncogenesis due to genomic integration preferences in transcriptional start sites (TSS). We have shifted the integration preferences of retroviral vectors by generating a library of viral variants with a DNA-binding domain inserted at random positions throughout murine leukemia virus Gag-Pol, then selecting for variants that are viable and exhibit altered integration properties. We found seven permissive zinc finger domain (ZFD) insertion sites throughout Gag-Pol, including within p12, reverse transcriptase, and integrase. Comprehensive genome integration analysis showed that several ZFD insertions yielded retroviral vector variants with shifted integration patterns that did not favor TSS. Furthermore, integration site analysis revealed selective integration for numerous mutants. For example, two retroviral variants with a given ZFD at appropriate positions in Gag-Pol strikingly integrated primarily into four common sites out of 3.1 × 109 possible human genome locations (P = 4.6 × 10-29). Our findings demonstrate that insertion of DNA-binding motifs into multiple locations in Gag-Pol can make considerable progress toward engineering safer retroviral vectors that integrate into a significantly narrowed pool of sites on human genome and overcome the preference for TSS. PMID:20616052

Recognition of blurred images by the method of moments.

PubMed

Flusser, J; Suk, T; Saic, S

1996-01-01

The article is devoted to the feature-based recognition of blurred images acquired by a linear shift-invariant imaging system against an image database. The proposed approach consists of describing images by features that are invariant with respect to blur and recognizing images in the feature space. The PSF identification and image restoration are not required. A set of symmetric blur invariants based on image moments is introduced. A numerical experiment is presented to illustrate the utilization of the invariants for blurred image recognition. Robustness of the features is also briefly discussed.

Advanced Imaging Optics Utilizing Wavefront Coding.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scrymgeour, David; Boye, Robert; Adelsberger, Kathleen

2015-06-01

Image processing offers a potential to simplify an optical system by shifting some of the imaging burden from lenses to the more cost effective electronics. Wavefront coding using a cubic phase plate combined with image processing can extend the system's depth of focus, reducing many of the focus-related aberrations as well as material related chromatic aberrations. However, the optimal design process and physical limitations of wavefront coding systems with respect to first-order optical parameters and noise are not well documented. We examined image quality of simulated and experimental wavefront coded images before and after reconstruction in the presence of noise.more » Challenges in the implementation of cubic phase in an optical system are discussed. In particular, we found that limitations must be placed on system noise, aperture, field of view and bandwidth to develop a robust wavefront coded system.« less

TH-A-9A-05: Initial Setup Accuracy Comparison Between Frame-Based and Frameless Stereotactic Radiosurgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tseng, T; Sheu, R; Todorov, B

2014-06-15

Purpose: To evaluate initial setup accuracy for stereotactic radiosurgery (SRS) between Brainlab frame-based and frameless immobilization system, also to discern the magnitude frameless system has on setup parameters. Methods: The correction shifts from the original setup were compared for total 157 SRS cranial treatments (69 frame-based vs. 88 frameless). All treatments were performed on a Novalis linac with ExacTrac positioning system. Localization box with isocenter overlay was used for initial setup and correction shift was determined by ExacTrac 6D auto-fusion to achieve submillimeter accuracy for treatment. For frameless treatments, mean time interval between simulation and treatment was 5.7 days (rangemore » 0–13). Pearson Chi-Square was used for univariate analysis. Results: The correctional radial shifts (mean±STD, median) for the frame and frameless system measured by ExacTrac were 1.2±1.2mm, 1.1mm and 3.1±3.3mm, 2.0mm, respectively. Treatments with frameless system had a radial shift >2mm more often than those with frames (51.1% vs. 2.9%; p<.0001). To achieve submillimeter accuracy, 85.5% frame-based treatments did not require shift and only 23.9% frameless treatment could succeed with initial setup. There was no statistical significant system offset observed in any direction for either system. For frameless treatments, those treated ≥ 3 days from simulation had statistically higher rates of radial shifts between 1–2mm and >2mm compared to patients treated in a shorter amount of time from simulation (34.3% and 56.7% vs. 28.6% and 33.3%, respectively; p=0.006). Conclusion: Although image-guided positioning system can also achieve submillimeter accuracy for frameless system, users should be cautious regarding the inherent uncertainty of its capability of immobilization. A proper quality assurance procedure for frameless mask manufacturing and a protocol for intra-fraction imaging verification will be crucial for frameless system. Time interval between simulation and treatment was influential to initial setup accuracy. A shorter time frame for frameless SRS treatment could be helpful in minimizing uncertainties in localization.« less

The UCL low-density lipoprotein receptor gene variant database: pathogenicity update

PubMed Central

Futema, Marta; Whittall, Ros; Taylor-Beadling, Alison; Williams, Maggie; den Dunnen, Johan T; Humphries, Steve E

2017-01-01

Background Familial hypercholesterolaemia (OMIM 143890) is most frequently caused by variations in the low-density lipoprotein receptor (LDLR) gene. Predicting whether novel variants are pathogenic may not be straightforward, especially for missense and synonymous variants. In 2013, the Association of Clinical Genetic Scientists published guidelines for the classification of variants, with categories 1 and 2 representing clearly not or unlikely pathogenic, respectively, 3 representing variants of unknown significance (VUS), and 4 and 5 representing likely to be or clearly pathogenic, respectively. Here, we update the University College London (UCL) LDLR variant database according to these guidelines. Methods PubMed searches and alerts were used to identify novel LDLR variants for inclusion in the database. Standard in silico tools were used to predict potential pathogenicity. Variants were designated as class 4/5 only when the predictions from the different programs were concordant and as class 3 when predictions were discordant. Results The updated database (http://www.lovd.nl/LDLR) now includes 2925 curated variants, representing 1707 independent events. All 129 nonsense variants, 337 small frame-shifting and 117/118 large rearrangements were classified as 4 or 5. Of the 795 missense variants, 115 were in classes 1 and 2, 605 in class 4 and 75 in class 3. 111/181 intronic variants, 4/34 synonymous variants and 14/37 promoter variants were assigned to classes 4 or 5. Overall, 112 (7%) of reported variants were class 3. Conclusions This study updates the LDLR variant database and identifies a number of reported VUS where additional family and in vitro studies will be required to confirm or refute their pathogenicity. PMID:27821657

Digitally enhanced homodyne interferometry.

PubMed

Sutton, Andrew J; Gerberding, Oliver; Heinzel, Gerhard; Shaddock, Daniel A

2012-09-24

We present two variations of a novel interferometry technique capable of simultaneously measuring multiple targets with high sensitivity. The technique performs a homodyne phase measurement by application of a four point phase shifting algorithm, with pseudo-random switching between points to allow multiplexed measurement based upon propagation delay alone. By multiplexing measurements and shifting complexity into signal processing, both variants realise significant complexity reductions over comparable methods. The first variant performs a typical coherent detection with a dedicated reference field and achieves a displacement noise floor 0.8 pm/√Hz above 50 Hz. The second allows for removal of the dedicated reference, resulting in further simplifications and improved low frequency performance with a 1 pm/√Hz noise floor measured down to 20 Hz. These results represent the most sensitive measurement performed using this style of interferometry whilst simultaneously reducing the electro-optic footprint.

Automated method and system for the alignment and correlation of images from two different modalities

DOEpatents

Giger, Maryellen L.; Chen, Chin-Tu; Armato, Samuel; Doi, Kunio

1999-10-26

A method and system for the computerized registration of radionuclide images with radiographic images, including generating image data from radiographic and radionuclide images of the thorax. Techniques include contouring the lung regions in each type of chest image, scaling and registration of the contours based on location of lung apices, and superimposition after appropriate shifting of the images. Specific applications are given for the automated registration of radionuclide lungs scans with chest radiographs. The method in the example given yields a system that spatially registers and correlates digitized chest radiographs with V/Q scans in order to correlate V/Q functional information with the greater structural detail of chest radiographs. Final output could be the computer-determined contours from each type of image superimposed on any of the original images, or superimposition of the radionuclide image data, which contains high activity, onto the radiographic chest image.

Full-field swept-source optical coherence tomography with phase-shifting techniques for skin cancer detection

NASA Astrophysics Data System (ADS)

Krauter, J.; Boettcher, T.; Körner, K.; Gronle, M.; Osten, W.; Passilly, N.; Froehly, L.; Perrin, S.; Gorecki, C.

2015-05-01

The EU-funded project VIAMOS1 proposes an optical coherence tomography system (OCT) for skin cancer detection, which combines full-field and full-range swept-source OCT in a multi-channel sensor for parallel detection. One of the project objectives is the development of new fabrication technologies for micro-optics, which makes it compatible to Micro-Opto-Electromechanical System technology (MOEMS). The basic system concept is a wafer-based Mirau interferometer array with an actuated reference mirror, which enables phase shifted interferogram detection and therefore reconstruction of the complex phase information, resulting in a higher measurement range with reduced image artifacts. This paper presents an experimental one-channel on-bench OCT system with bulk optics, which serves as a proof-of-concept setup for the final VIAMOS micro-system. It is based on a Linnik interferometer with a wavelength tuning light source and a camera for parallel A-Scan detection. Phase shifting interferometry techniques (PSI) are used for the suppression of the complex conjugate artifact, whose suppression reaches 36 dB. The sensitivity of the system is constant over the full-field with a mean value of 97 dB. OCT images are presented of a thin membrane microlens and a biological tissue (onion) as a preliminary demonstration.

Comprehensive approach to image-guided surgery

NASA Astrophysics Data System (ADS)

Peters, Terence M.; Comeau, Roch M.; Kasrai, Reza; St. Jean, Philippe; Clonda, Diego; Sinasac, M.; Audette, Michel A.; Fenster, Aaron

1998-06-01

Image-guided surgery has evolved over the past 15 years from stereotactic planning, where the surgeon planned approaches to intracranial targets on the basis of 2D images presented on a simple workstation, to the use of sophisticated multi- modality 3D image integration in the operating room, with guidance being provided by mechanically, optically or electro-magnetically tracked probes or microscopes. In addition, sophisticated procedures such as thalamotomies and pallidotomies to relieve the symptoms of Parkinson's disease, are performed with the aid of volumetric atlases integrated with the 3D image data. Operations that are performed stereotactically, that is to say via a small burr- hole in the skull, are able to assume that the information contained in the pre-operative imaging study, accurately represents the brain morphology during the surgical procedure. On the other hand, preforming a procedure via an open craniotomy presents a problem. Not only does tissue shift when the operation begins, even the act of opening the skull can cause significant shift of the brain tissue due to the relief of intra-cranial pressure, or the effect of drugs. Means of tracking and correcting such shifts from an important part of the work in the field of image-guided surgery today. One approach has ben through the development of intra-operative MRI imaging systems. We describe an alternative approach which integrates intra-operative ultrasound with pre-operative MRI to track such changes in tissue morphology.

High Resolution Image Reconstruction from Projection of Low Resolution Images DIffering in Subpixel Shifts

NASA Technical Reports Server (NTRS)

Mareboyana, Manohar; Le Moigne-Stewart, Jacqueline; Bennett, Jerome

2016-01-01

In this paper, we demonstrate a simple algorithm that projects low resolution (LR) images differing in subpixel shifts on a high resolution (HR) also called super resolution (SR) grid. The algorithm is very effective in accuracy as well as time efficiency. A number of spatial interpolation techniques using nearest neighbor, inverse-distance weighted averages, Radial Basis Functions (RBF) etc. used in projection yield comparable results. For best accuracy of reconstructing SR image by a factor of two requires four LR images differing in four independent subpixel shifts. The algorithm has two steps: i) registration of low resolution images and (ii) shifting the low resolution images to align with reference image and projecting them on high resolution grid based on the shifts of each low resolution image using different interpolation techniques. Experiments are conducted by simulating low resolution images by subpixel shifts and subsampling of original high resolution image and the reconstructing the high resolution images from the simulated low resolution images. The results of accuracy of reconstruction are compared by using mean squared error measure between original high resolution image and reconstructed image. The algorithm was tested on remote sensing images and found to outperform previously proposed techniques such as Iterative Back Projection algorithm (IBP), Maximum Likelihood (ML), and Maximum a posterior (MAP) algorithms. The algorithm is robust and is not overly sensitive to the registration inaccuracies.

Phased array ghost elimination.

PubMed

Kellman, Peter; McVeigh, Elliot R

2006-05-01

Parallel imaging may be applied to cancel ghosts caused by a variety of distortion mechanisms, including distortions such as off-resonance or local flow, which are space variant. Phased array combining coefficients may be calculated that null ghost artifacts at known locations based on a constrained optimization, which optimizes SNR subject to the nulling constraint. The resultant phased array ghost elimination (PAGE) technique is similar to the method known as sensitivity encoding (SENSE) used for accelerated imaging; however, in this formulation is applied to full field-of-view (FOV) images. The phased array method for ghost elimination may result in greater flexibility in designing acquisition strategies. For example, in multi-shot EPI applications ghosts are typically mitigated by the use of an interleaved phase encode acquisition order. An alternative strategy is to use a sequential, non-interleaved phase encode order and cancel the resultant ghosts using PAGE parallel imaging. Cancellation of ghosts by means of phased array processing makes sequential, non-interleaved phase encode acquisition order practical, and permits a reduction in repetition time, TR, by eliminating the need for echo-shifting. Sequential, non-interleaved phase encode order has benefits of reduced distortion due to off-resonance, in-plane flow and EPI delay misalignment. Furthermore, the use of EPI with PAGE has inherent fat-water separation and has been used to provide off-resonance correction using a technique referred to as lipid elimination with an echo-shifting N/2-ghost acquisition (LEENA), and may further generalized using the multi-point Dixon method. Other applications of PAGE include cancelling ghosts which arise due to amplitude or phase variation during the approach to steady state. Parallel imaging requires estimates of the complex coil sensitivities. In vivo estimates may be derived by temporally varying the phase encode ordering to obtain a full k-space dataset in a scheme similar to the autocalibrating TSENSE method. This scheme is a generalization of the UNFOLD method used for removing aliasing in undersampled acquisitions. The more general scheme may be used to modulate each EPI ghost image to a separate temporal frequency as described in this paper. Copyright (c) 2006 John Wiley & Sons, Ltd.

Phased array ghost elimination

PubMed Central

Kellman, Peter; McVeigh, Elliot R.

2007-01-01

Parallel imaging may be applied to cancel ghosts caused by a variety of distortion mechanisms, including distortions such as off-resonance or local flow, which are space variant. Phased array combining coefficients may be calculated that null ghost artifacts at known locations based on a constrained optimization, which optimizes SNR subject to the nulling constraint. The resultant phased array ghost elimination (PAGE) technique is similar to the method known as sensitivity encoding (SENSE) used for accelerated imaging; however, in this formulation is applied to full field-of-view (FOV) images. The phased array method for ghost elimination may result in greater flexibility in designing acquisition strategies. For example, in multi-shot EPI applications ghosts are typically mitigated by the use of an interleaved phase encode acquisition order. An alternative strategy is to use a sequential, non-interleaved phase encode order and cancel the resultant ghosts using PAGE parallel imaging. Cancellation of ghosts by means of phased array processing makes sequential, non-interleaved phase encode acquisition order practical, and permits a reduction in repetition time, TR, by eliminating the need for echo-shifting. Sequential, non-interleaved phase encode order has benefits of reduced distortion due to off-resonance, in-plane flow and EPI delay misalignment. Furthermore, the use of EPI with PAGE has inherent fat-water separation and has been used to provide off-resonance correction using a technique referred to as lipid elimination with an echo-shifting N/2-ghost acquisition (LEENA), and may further generalized using the multi-point Dixon method. Other applications of PAGE include cancelling ghosts which arise due to amplitude or phase variation during the approach to steady state. Parallel imaging requires estimates of the complex coil sensitivities. In vivo estimates may be derived by temporally varying the phase encode ordering to obtain a full k-space dataset in a scheme similar to the autocalibrating TSENSE method. This scheme is a generalization of the UNFOLD method used for removing aliasing in undersampled acquisitions. The more general scheme may be used to modulate each EPI ghost image to a separate temporal frequency as described in this paper. PMID:16705636

A Bright and Fast Red Fluorescent Protein Voltage Indicator That Reports Neuronal Activity in Organotypic Brain Slices

PubMed Central

Abdelfattah, Ahmed S.; Farhi, Samouil L.; Zhao, Yongxin; Brinks, Daan; Zou, Peng; Ruangkittisakul, Araya; Platisa, Jelena; Pieribone, Vincent A.; Ballanyi, Klaus; Cohen, Adam E.

2016-01-01

Optical imaging of voltage indicators based on green fluorescent proteins (FPs) or archaerhodopsin has emerged as a powerful approach for detecting the activity of many individual neurons with high spatial and temporal resolution. Relative to green FP-based voltage indicators, a bright red-shifted FP-based voltage indicator has the intrinsic advantages of lower phototoxicity, lower autofluorescent background, and compatibility with blue-light-excitable channelrhodopsins. Here, we report a bright red fluorescent voltage indicator (fluorescent indicator for voltage imaging red; FlicR1) with properties that are comparable to the best available green indicators. To develop FlicR1, we used directed protein evolution and rational engineering to screen libraries of thousands of variants. FlicR1 faithfully reports single action potentials (∼3% ΔF/F) and tracks electrically driven voltage oscillations at 100 Hz in dissociated Sprague Dawley rat hippocampal neurons in single trial recordings. Furthermore, FlicR1 can be easily imaged with wide-field fluorescence microscopy. We demonstrate that FlicR1 can be used in conjunction with a blue-shifted channelrhodopsin for all-optical electrophysiology, although blue light photoactivation of the FlicR1 chromophore presents a challenge for applications that require spatially overlapping yellow and blue excitation. SIGNIFICANCE STATEMENT Fluorescent-protein-based voltage indicators enable imaging of the electrical activity of many genetically targeted neurons with high spatial and temporal resolution. Here, we describe the engineering of a bright red fluorescent protein-based voltage indicator designated as FlicR1 (fluorescent indicator for voltage imaging red). FlicR1 has sufficient speed and sensitivity to report single action potentials and voltage fluctuations at frequencies up to 100 Hz in single-trial recordings with wide-field microscopy. Because it is excitable with yellow light, FlicR1 can be used in conjunction with blue-light-activated optogenetic actuators. However, spatially distinct patterns of optogenetic activation and voltage imaging are required to avoid fluorescence artifacts due to photoactivation of the FlicR1 chromophore. PMID:26911693

Precise Aperture-Dependent Motion Compensation with Frequency Domain Fast Back-Projection Algorithm.

PubMed

Zhang, Man; Wang, Guanyong; Zhang, Lei

2017-10-26

Precise azimuth-variant motion compensation (MOCO) is an essential and difficult task for high-resolution synthetic aperture radar (SAR) imagery. In conventional post-filtering approaches, residual azimuth-variant motion errors are generally compensated through a set of spatial post-filters, where the coarse-focused image is segmented into overlapped blocks concerning the azimuth-dependent residual errors. However, image domain post-filtering approaches, such as precise topography- and aperture-dependent motion compensation algorithm (PTA), have difficulty of robustness in declining, when strong motion errors are involved in the coarse-focused image. In this case, in order to capture the complete motion blurring function within each image block, both the block size and the overlapped part need necessary extension leading to degeneration of efficiency and robustness inevitably. Herein, a frequency domain fast back-projection algorithm (FDFBPA) is introduced to deal with strong azimuth-variant motion errors. FDFBPA disposes of the azimuth-variant motion errors based on a precise azimuth spectrum expression in the azimuth wavenumber domain. First, a wavenumber domain sub-aperture processing strategy is introduced to accelerate computation. After that, the azimuth wavenumber spectrum is partitioned into a set of wavenumber blocks, and each block is formed into a sub-aperture coarse resolution image via the back-projection integral. Then, the sub-aperture images are straightforwardly fused together in azimuth wavenumber domain to obtain a full resolution image. Moreover, chirp-Z transform (CZT) is also introduced to implement the sub-aperture back-projection integral, increasing the efficiency of the algorithm. By disusing the image domain post-filtering strategy, robustness of the proposed algorithm is improved. Both simulation and real-measured data experiments demonstrate the effectiveness and superiority of the proposal.

Rates of Amyloid Imaging Positivity in Patients With Primary Progressive Aphasia

PubMed Central

Santos-Santos, Miguel A.; Rabinovici, Gil D.; Iaccarino, Leonardo; Ayakta, Nagehan; Tammewar, Gautam; Lobach, Iryna; Henry, Maya L.; Hubbard, Isabel; Mandelli, Maria Luisa; Spinelli, Edoardo; Miller, Zachary A.; Pressman, Peter S.; O’Neil, James P.; Ghosh, Pia; Lazaris, Andreas; Meyer, Marita; Watson, Christa; Yoon, Soo Jin; Rosen, Howard J.; Grinberg, Lea; Seeley, William W.; Miller, Bruce L.; Jagust, William J.; Gorno-Tempini, Maria Luisa

2018-01-01

IMPORTANCE The ability to predict the pathology underlying different neurodegenerative syndromes is of critical importance owing to the advent of molecule-specific therapies. OBJECTIVE To determine the rates of positron emission tomography (PET) amyloid positivity in the main clinical variants of primary progressive aphasia (PPA). DESIGN, SETTING, AND PARTICIPANTS This prospective clinical-pathologic case series was conducted at a tertiary research clinic specialized in cognitive disorders. Patients were evaluated as part of a prospective, longitudinal research study between January 2002 and December 2015. Inclusion criteria included clinical diagnosis of PPA; availability of complete speech, language, and cognitive testing; magnetic resonance imaging performed within 6 months of the cognitive evaluation; and PET carbon 11–labeled Pittsburgh Compound-B or florbetapir F 18 brain scan results. Of 109 patients referred for evaluation of language symptoms who underwent amyloid brain imaging, 3 were excluded because of incomplete language evaluations, 5 for absence of significant aphasia, and 12 for presenting with significant initial symptoms outside of the language domain, leaving a cohort of 89 patients with PPA. MAIN OUTCOMES AND MEASURES Clinical, cognitive, neuroimaging, and pathology results. RESULTS Twenty-eight cases were classified as imaging-supported semantic variant PPA (11 women [39.3%]; mean [SD] age, 64 [7] years), 31 nonfluent/agrammatic variant PPA (22 women [71.0%]; mean [SD] age, 68 [7] years), 26 logopenic variant PPA (17 women [65.4%]; mean [SD] age, 63 [8] years), and 4 mixed PPA cases. Twenty-four of 28 patients with semantic variant PPA (86%) and 28 of 31 patients with nonfluent/agrammatic variant PPA (90%) had negative amyloid PET scan results, while 25 of 26 patients with logopenic variant PPA (96%) and 3 of 4 mixed PPA cases (75%) had positive scan results. The amyloid positive semantic variant PPA and nonfluent/agrammatic variant PPA cases with available autopsy data (2 of 4 and 2 of 3, respectively) all had a primary frontotemporal lobar degeneration and secondary Alzheimer disease pathologic diagnoses, whereas autopsy of 2 patients with amyloid PET–positive logopenic variant PPA confirmed Alzheimer disease. One mixed PPA patient with a negative amyloid PET scan had Pick disease at autopsy. CONCLUSIONS AND RELEVANCE Primary progressive aphasia variant diagnosis according to the current classification scheme is associated with Alzheimer disease biomarker status, with the logopenic variant being associated with carbon 11–labeled Pittsburgh Compound-B positivity in more than 95% of cases. Furthermore, in the presence of a clinical syndrome highly predictive of frontotemporal lobar degeneration pathology, biomarker positivity for Alzheimer disease may be associated more with mixed pathology rather than primary Alzheimer disease. PMID:29309493

Excitation and characterization of image potential state electrons on quasi-free-standing graphene

NASA Astrophysics Data System (ADS)

Lin, Yi; Li, Yunzhe; Sadowski, Jerzy T.; Jin, Wencan; Dadap, Jerry I.; Hybertsen, Mark S.; Osgood, Richard M.

2018-04-01

We investigate the band structure of image potential states in quasi-free-standing graphene (QFG) monolayer islands using angle-resolved two-photon-photoemission spectroscopy. Direct probing by low-energy electron diffraction shows that QFG is formed following oxygen intercalation into the graphene-Ir(111) interface. Despite the apparent decoupling of the monolayer graphene from the Ir substrate, we find that the binding energy of the n =1 image potential state on these QFG islands increases by 0.17 eV, as compared to the original Gr/Ir(111) interface. We use calculations based on density-functional theory to construct an empirical, one-dimensional potential that quantitatively reproduces the image potential state binding energy and links the changes in the interface structure to the shift in energy. Specifically, two factors contribute comparably to this energy shift: a deeper potential well arising from the presence of intercalated oxygen adatoms and a wider potential well associated with the increase in the graphene-Ir distance. While image potential states have not been observed previously on QFG by photoemission, our paper now demonstrates that they may be strongly excited in a well-defined QFG system produced by oxygen intercalation. This opens an opportunity for studying the surface electron dynamics in QFG systems, beyond those found in typical nonintercalated graphene-on-substrate systems.

Using advertisement light-panel and CMOS image sensor with frequency-shift-keying for visible light communication.

PubMed

Chow, Chi-Wai; Shiu, Ruei-Jie; Liu, Yen-Chun; Liao, Xin-Lan; Lin, Kun-Hsien; Wang, Yi-Chang; Chen, Yi-Yuan

2018-05-14

A frequency-shift-keying (FSK) visible light communication (VLC) system is proposed and demonstrated using advertisement light-panel as transmitter and mobile-phone image sensor as receiver. The developed application program (APP) in mobile-phone can retrieve the rolling shutter effect (RSE) pattern produced by the FSK VLC signal effectively. Here, we also define noise-ratio value (NRV) to evaluate the contrast of different advertisements displayed on the light-panel. Both mobile-phones under test can achieve success rate > 96% even when the transmission distance is up to 200 cm and the NRVs are low.

Inverting a dispersive scene's side-scanned image

NASA Technical Reports Server (NTRS)

Harger, R. O.

1983-01-01

Consideration is given to the problem of using a remotely sensed, side-scanned image of a time-variant scene, which changes according to a dispersion relation, to estimate the structure at a given moment. Additive thermal noise is neglected in the models considered in the formal treatment. It is shown that the dispersion relation is normalized by the scanning velocity, as is the group scanning velocity component. An inversion operation is defined for noise-free images generated by SAR. The method is extended to the inversion of noisy imagery, and a formulation is defined for spectral density estimation. Finally, the methods for a radar system are used for the case of sonar.

Quantitative approach for optimizing e-beam condition of photoresist inspection and measurement

NASA Astrophysics Data System (ADS)

Lin, Chia-Jen; Teng, Chia-Hao; Cheng, Po-Chung; Sato, Yoshishige; Huang, Shang-Chieh; Chen, Chu-En; Maruyama, Kotaro; Yamazaki, Yuichiro

2018-03-01

Severe process margin in advanced technology node of semiconductor device is controlled by e-beam metrology system and e-beam inspection system with scanning electron microscopy (SEM) image. By using SEM, larger area image with higher image quality is required to collect massive amount of data for metrology and to detect defect in a large area for inspection. Although photoresist is the one of the critical process in semiconductor device manufacturing, observing photoresist pattern by SEM image is crucial and troublesome especially in the case of large image. The charging effect by e-beam irradiation on photoresist pattern causes deterioration of image quality, and it affect CD variation on metrology system and causes difficulties to continue defect inspection in a long time for a large area. In this study, we established a quantitative approach for optimizing e-beam condition with "Die to Database" algorithm of NGR3500 on photoresist pattern to minimize charging effect. And we enhanced the performance of measurement and inspection on photoresist pattern by using optimized e-beam condition. NGR3500 is the geometry verification system based on "Die to Database" algorithm which compares SEM image with design data [1]. By comparing SEM image and design data, key performance indicator (KPI) of SEM image such as "Sharpness", "S/N", "Gray level variation in FOV", "Image shift" can be retrieved. These KPIs were analyzed with different e-beam conditions which consist of "Landing Energy", "Probe Current", "Scanning Speed" and "Scanning Method", and the best e-beam condition could be achieved with maximum image quality, maximum scanning speed and minimum image shift. On this quantitative approach of optimizing e-beam condition, we could observe dependency of SEM condition on photoresist charging. By using optimized e-beam condition, measurement could be continued on photoresist pattern over 24 hours stably. KPIs of SEM image proved image quality during measurement and inspection was stabled enough.

Evaluation of a novel compact shearography system with DOE configuration

NASA Astrophysics Data System (ADS)

da Silva, Fabio Aparecido Alves; Willemann, Daniel Pedro; Fantin, Analucia Vieira; Benedet, Mauro Eduardo; Gonçalves, Armando Albertazzi

2018-05-01

The most common optical configuration used to produce the lateral shifted images, in a Shearography system, is the Modified Michelson interferometer, because of its simple configuration. Tests carried out in recent years have shown that the modified interferometer of Michelson is a device that presents good results in a laboratory environment, but still presents difficulties in the field. These difficulties were the main motivation for the development of a more robust system, able to operate in unstable environments. This paper presents a new shearography configuration based on Diffractive Optical Element (DOE). Different from the diffractive common-path setups found in literature, in the proposed configuration, the DOE is positioned between the image sensor and the objective lens and mounted on a flexible holder, which has an important function to promote the system's robustness. Another advantage of the proposed system is in respect to phase shifting, since it is insensitive to wavelength variations. The lateral movement of the DOE produces a phase shifting in the shearography system. Since the pitch of the diffractive grating used is about 60 times greater than the wavelength of a green laser, the DOE configuration becomes much more robust to external influences compared to the Michelson Interferometer configuration. This work also presents an evaluation of the proposed shearography system designed, and some comparative results regarding a classical shearography system.

Dependence of Adaptive Cross-correlation Algorithm Performance on the Extended Scene Image Quality

NASA Technical Reports Server (NTRS)

Sidick, Erkin

2008-01-01

Recently, we reported an adaptive cross-correlation (ACC) algorithm to estimate with high accuracy the shift as large as several pixels between two extended-scene sub-images captured by a Shack-Hartmann wavefront sensor. It determines the positions of all extended-scene image cells relative to a reference cell in the same frame using an FFT-based iterative image-shifting algorithm. It works with both point-source spot images as well as extended scene images. We have demonstrated previously based on some measured images that the ACC algorithm can determine image shifts with as high an accuracy as 0.01 pixel for shifts as large 3 pixels, and yield similar results for both point source spot images and extended scene images. The shift estimate accuracy of the ACC algorithm depends on illumination level, background, and scene content in addition to the amount of the shift between two image cells. In this paper we investigate how the performance of the ACC algorithm depends on the quality and the frequency content of extended scene images captured by a Shack-Hatmann camera. We also compare the performance of the ACC algorithm with those of several other approaches, and introduce a failsafe criterion for the ACC algorithm-based extended scene Shack-Hatmann sensors.

Electrophoretic Mobility Shift Assay (EMSA) for Detecting Protein-Nucleic Acid Interactions

PubMed Central

Hellman, Lance M.; Fried, Michael G.

2009-01-01

The gel electrophoresis mobility shift assay (EMSA) is used to detect protein complexes with nucleic acids. It is the core technology underlying a wide range of qualitative and quantitative analyses for the characterization of interacting systems. In the classical assay, solutions of protein and nucleic acid are combined and the resulting mixtures are subjected to electrophoresis under native conditions through polyacrylamide or agarose gel. After electrophoresis, the distribution of species containing nucleic acid is determined, usually by autoradiography of 32P-labeled nucleic acid. In general, protein-nucleic acid complexes migrate more slowly than the corresponding free nucleic acid. In this article, we identify the most important factors that determine the stabilities and electrophoretic mobilities of complexes under assay conditions. A representative protocol is provided and commonly used variants are discussed. Expected outcomes are briefly described. References to extensions of the method and a troubleshooting guide are provided. PMID:17703195

SU-F-P-32: A Phantom Study of Accuracy of Four-Dimensional Cone-Beam CT (4D-CBCT) Vs. Three-Dimensional Cone Beam CT (3D-CBCT) in Image Guided Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, R; Morris, B; Duggar, N

2016-06-15

Purpose: SymmetryTM 4D IGRT system of Elekta has been installed at our institution, which offers the 4D CBCT registration option. This study is to evaluate the accuracy of 4D CBCT system by using the CIRS 4D motion phantom and to perform a feasibility study on the implementation of 4D-CBCT as image guidance for SBRT treatment. Methods: The 3D and 4D CT image data sets are acquired using the CIRS motion phantom on a Philips large bore CT simulator. The motion was set as 0.5 cm superior and inferior directions with 6 seconds recycle time. The 4D CT data were sortedmore » as 10 phases. One identifiable part of the 4D CT QA insert from CIRS phantom was used as the target. The ITV MIP was drawn based on maximum intensity projection (MIP) and transferred as a planning structure into 4D CBCT system. Then the 3D CBCT and 4D CBCT images were taken and registered with the free breath (3D), MIP (4D) and average intensity projection (AIP)(4D) reference data sets. The couch shifts (X, Y, Z) are recorded and compared. Results: Table 1 listed the twelve couch shifts based on the registration of MIP, AIP and free breath CT data sets with 3D CBCT and 4D CBCT for both whole body and local registration. X, Y and Z represent couch shifts in the direction of the right-left, superior-inferior and anterior-posterior. The biggest differences of 0.73 cm and 0.57 cm are noted in the free breath CT data with 4D CBCT and 3D CBCT data registration. Fig. 1 and Fig. 2 are the shift analysis in diagram. Fig. 3 shows the registration. Conclusion: Significant differences exist in the shifts corresponding with the direction of target motion. Further investigations are ongoing.« less

Discriminatory power of common genetic variants in personalized breast cancer diagnosis

NASA Astrophysics Data System (ADS)

Wu, Yirong; Abbey, Craig K.; Liu, Jie; Ong, Irene; Peissig, Peggy; Onitilo, Adedayo A.; Fan, Jun; Yuan, Ming; Burnside, Elizabeth S.

2016-03-01

Technology advances in genome-wide association studies (GWAS) has engendered optimism that we have entered a new age of precision medicine, in which the risk of breast cancer can be predicted on the basis of a person's genetic variants. The goal of this study is to evaluate the discriminatory power of common genetic variants in breast cancer risk estimation. We conducted a retrospective case-control study drawing from an existing personalized medicine data repository. We collected variables that predict breast cancer risk: 153 high-frequency/low-penetrance genetic variants, reflecting the state-of-the-art GWAS on breast cancer, mammography descriptors and BI-RADS assessment categories in the Breast Imaging Reporting and Data System (BI-RADS) lexicon. We trained and tested naïve Bayes models by using these predictive variables. We generated ROC curves and used the area under the ROC curve (AUC) to quantify predictive performance. We found that genetic variants achieved comparable predictive performance to BI-RADS assessment categories in terms of AUC (0.650 vs. 0.659, p-value = 0.742), but significantly lower predictive performance than the combination of BI-RADS assessment categories and mammography descriptors (0.650 vs. 0.751, p-value < 0.001). A better understanding of relative predictive capability of genetic variants and mammography data may benefit clinicians and patients to make appropriate decisions about breast cancer screening, prevention, and treatment in the era of precision medicine.

Virtual Whipple: preoperative surgical planning with volume-rendered MDCT images to identify arterial variants relevant to the Whipple procedure.

PubMed

Brennan, Darren D; Zamboni, Giulia; Sosna, Jacob; Callery, Mark P; Vollmer, Charles M V; Raptopoulos, Vassilios D; Kruskal, Jonathan B

2007-05-01

The purposes of this study were to combine a thorough understanding of the technical aspects of the Whipple procedure with advanced rendering techniques by introducing a virtual Whipple procedure and to evaluate the utility of this new rendering technique in prediction of the arterial variants that cross the anticipated surgical resection plane. The virtual Whipple is a novel technique that follows the complex surgical steps in a Whipple procedure. Three-dimensional reconstructed angiographic images are used to identify arterial variants for the surgeon as part of the preoperative radiologic assessment of pancreatic and ampullary tumors.

Image Formation in High Contrast Optical Systems: The Role of Polarization

NASA Technical Reports Server (NTRS)

Breckinridge, James B.

2004-01-01

To find evidence of life in the Universe outside our solar system is one of the most compelling and visionary adventures of the 21st century. The technologies to create the telescopes and instruments that will enable this discovery are now within the grasp of mankind. Direct imaging of a very faint planet around a neighboring bright star requires high contrast or a hypercontrast optical imaging system capable of controlling unwanted radiation within the system to one part in ten to the 11th. This paper identifies several physical phenomena that affect image quality in high contrast imaging systems. Polarization induced at curved metallic surfaces and by anisotropy in the deposition process (Smith-Purcell effect) along with beam shifts introduced by the Goos-Hachen effect are discussed. A typical configuration is analyzed, and technical risk mitigation concepts are discussed.

New Developments in Observer Performance Methodology in Medical Imaging

PubMed Central

Chakraborty, Dev P.

2011-01-01

A common task in medical imaging is assessing whether a new imaging system, or a variant of an existing one, is an improvement over an existing imaging technology. Imaging systems are generally quite complex, consisting of several components – e.g., image acquisition hardware, image processing and display hardware and software, and image interpretation by radiologists– each of which can affect performance. While it may appear odd to include the radiologist as a “component” of the imaging chain, since the radiologist’s decision determines subsequent patient care, the effect of the human interpretation has to be included. Physical measurements like modulation transfer function, signal to noise ratio, etc., are useful for characterizing the non-human parts of the imaging chain under idealized and often unrealistic conditions, such as uniform background phantoms, target objects with sharp edges, etc. Measuring the effect on performance of the entire imaging chain, including the radiologist, and using real clinical images, requires different methods that fall under the rubric of observer performance methods or “ROC analysis”. The purpose of this paper is to review recent developments in this field, particularly with respect to the free-response method. PMID:21978444

Computer graphics testbed to simulate and test vision systems for space applications

NASA Technical Reports Server (NTRS)

Cheatham, John B.

1991-01-01

Research activity has shifted from computer graphics and vision systems to the broader scope of applying concepts of artificial intelligence to robotics. Specifically, the research is directed toward developing Artificial Neural Networks, Expert Systems, and Laser Imaging Techniques for Autonomous Space Robots.

Fab MOR03268 triggers absorption shift of a diagnostic dye via packaging in a solvent-shielded Fab dimer interface.

PubMed

Hillig, Roman C; Urlinger, Stefanie; Fanghänel, Jörg; Brocks, Bodo; Haenel, Cornelia; Stark, Yvonne; Sülzle, Detlev; Svergun, Dmitri I; Baesler, Siegfried; Malawski, Guido; Moosmayer, Dieter; Menrad, Andreas; Schirner, Michael; Licha, Kai

2008-03-14

Molecular interactions between near-IR fluorescent probes and specific antibodies may be exploited to generate novel smart probes for diagnostic imaging. Using a new phage display technology, we developed such antibody Fab fragments with subnanomolar binding affinity for tetrasulfocyanine, a near-IR in vivo imaging agent. Unexpectedly, some Fabs induced redshifts of the dye absorption peak of up to 44 nm. This is the largest shift reported for a biological system so far. Crystal structure determination and absorption spectroscopy in the crystal in combination with microcalorimetry and small-angle X-ray scattering in solution revealed that the redshift is triggered by formation of a Fab dimer, with tetrasulfocyanine being buried in a fully closed protein cavity within the dimer interface. The derived principle of shifting the absorption peak of a symmetric dye via packaging within a Fab dimer interface may be transferred to other diagnostic fluorophores, opening the way towards smart imaging probes that change their wavelength upon interaction with an antibody.

White matter pathology in ALS and lower motor neuron ALS variants: a diffusion tensor imaging study using tract-based spatial statistics.

PubMed

Prudlo, Johannes; Bißbort, Charlotte; Glass, Aenne; Grossmann, Annette; Hauenstein, Karlheinz; Benecke, Reiner; Teipel, Stefan J

2012-09-01

The aim of this work was to investigate white-matter microstructural changes within and outside the corticospinal tract in classical amyotrophic lateral sclerosis (ALS) and in lower motor neuron (LMN) ALS variants by means of diffusion tensor imaging (DTI). We investigated 22 ALS patients and 21 age-matched controls utilizing a whole-brain approach with a 1.5-T scanner for DTI. The patient group was comprised of 15 classical ALS- and seven LMN ALS-variant patients (progressive muscular atrophy, flail arm and flail leg syndrome). Disease severity was measured by the revised version of the functional rating scale. White matter fractional anisotropy (FA) was assessed using tract-based spatial statistics (TBSS) and a region of interest (ROI) approach. We found significant FA reductions in motor and extra-motor cerebral fiber tracts in classical ALS and in the LMN ALS-variant patients compared to controls. The voxel-based TBSS results were confirmed by the ROI findings. The white matter damage correlated with the disease severity in the patient group and was found in a similar distribution, but to a lesser extent, among the LMN ALS-variant subgroup. ALS and LMN ALS variants are multisystem degenerations. DTI shows the potential to determine an earlier diagnosis, particularly in LMN ALS variants. The statistically identical findings of white matter lesions in classical ALS and LMN variants as ascertained by DTI further underline that these variants should be regarded as part of the ALS spectrum.

Dose equations for shift-variant CT acquisition modes using variable pitch, tube current, and aperture, and the meaning of their associated CTDI{sub vol}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dixon, Robert L., E-mail: rdixon@wfubmc.edu; Boone, John M.; Kraft, Robert A.

2014-11-01

Purpose: With the increasing clinical use of shift-variant CT protocols involving tube current modulation (TCM), variable pitch or pitch modulation (PM), and variable aperture a(t), the interpretation of the scanner-reported CTDI{sub vol} is called into question. This was addressed for TCM in their previous paper published by Dixon and Boone [Med. Phys. 40, 111920 (14pp.) (2013)] and is extended to PM and concurrent TCM/PM as well as variable aperture in this work. Methods: Rigorous convolution equations are derived to describe the accumulated dose distributions for TCM, PM, and concurrent TCM/PM. A comparison with scanner-reported CTDI{sub vol} formulae clearly identifies themore » source of their differences with the traditional CTDI{sub vol}. Dose distribution simulations using the convolution are provided for a variety of TCM and PM scenarios including a helical shuttle used for perfusion studies (as well as constant mA)—all having the same scanner-reported CTDI{sub vol}. These new convolution simulations for TCM are validated by comparison with their previous discrete summations. Results: These equations show that PM is equivalent to TCM if the pitch variation p(z) is proportional to 1/i(z), where i(z) is the local tube current. The simulations show that the local dose at z depends only weakly on the local tube current i(z) or local pitch p(z) due to scatter from all other locations along z, and that the “local CTDI{sub vol}(z)” or “CTDI{sub vol} per slice” do not represent a local dose but rather only a relative i(z) or p(z). The CTDI-paradigm does not apply to shift-variant techniques and the scanner-reported CTDI{sub vol} for the same lacks physical significance and relevance. Conclusions: While the traditional CTDI{sub vol} at constant tube current and pitch conveys useful information (the peak dose at the center of the scan length), CTDI{sub vol} for shift-variant techniques (TCM or PM) conveys no useful information about the associated dose distribution it purportedly represents. On the other hand, the total energy absorbed E (“integral dose”) as well as its surrogate DLP remain robust (invariant) with respect to shift-variance, depending only on the total mAs = 〈i〉t{sub 0} accumulated during the total beam-on time t{sub 0} and aperture a, where 〈i〉 is the average current.« less

Joint transform correlators with spatially incoherent illumination

NASA Astrophysics Data System (ADS)

Bykovsky, Yuri A.; Karpiouk, Andrey B.; Markilov, Anatoly A.; Rodin, Vladislav G.; Starikov, Sergey N.

1997-03-01

Two variants of joint transform correlators with monochromatic spatially incoherent illumination are considered. The Fourier-holograms of the reference and recognized images are recorded simultaneously or apart in a time on the same spatial light modulator directly by monochromatic spatially incoherent light. To create the signal of mutual correlation of the images it is necessary to execute nonlinear transformation when the hologram is illuminated by coherent light. In the first scheme of the correlator this aim was achieved by using double pas of a restoring coherent wave through the hologram. In the second variant of the correlator the non-linearity of the characteristic of the spatial light modulator for hologram recording was used. Experimental schemes and results on processing teste images by both variants of joint transform correlators with monochromatic spatially incoherent illumination. The use of spatially incoherent light on the input of joint transform correlators permits to reduce the requirements to optical quality of elements, to reduce accuracy requirements on elements positioning and to expand a number of devices suitable to input images in correlators.

Noninvasive analysis of human neck muscle function

NASA Technical Reports Server (NTRS)

Conley, M. S.; Meyer, R. A.; Bloomberg, J. J.; Feeback, D. L.; Dudley, G. A.

1995-01-01

STUDY DESIGN. Muscle use evoked by exercise was determined by quantifying shifts in signal relaxation times of T2-weighted magnetic resonance images. Images were collected at rest and after exercise at each of two intensities (moderate and intense) for each of four head movements: 1) extension, 2) flexion, 3) rotation, and 4) lateral flexion. OBJECTIVE. This study examined the intensity and pattern of neck muscle use evoked by various movements of the head. The results will help elucidate the pathophysiology, and thus methods for treating disorders of the cervical musculoskeletal system. SUMMARY OF BACKGROUND DATA. Exercise-induced contrast shifts in T2 has been shown to indicate muscle use during the activity. The noninvasive nature of magnetic resonance imaging appears to make it an ideal approach for studying the function of the complex neuromuscular system of the neck. METHODS. The extent of T2 increase was examined to gauge how intensely nine different neck muscles or muscle pairs were used in seven subjects. The absolute and relative cross-sectional area of muscle showing a shift in signal relaxation was assessed to infer the pattern of use among and within individual neck muscles or muscle pairs. RESULTS. Signal relaxation increased with exercise intensity for each head movement. The absolute and relative cross-sectional area of muscle showing a shift in signal relaxation also increased with exercise load. Neck muscles or muscle pairs extensively used to perform each head movement were: extension--semispinalis capitis and cervicis and splenius capitis; flexion--sternocleidomastoid and longus capitis and colli; rotation--splenius capitis, levator scapulae, scalenus, semispinalis capitis ipsilateral to the rotation, and sternocleidomastoid contralateral; and lateral flexion--sternocleidomastoid CONCLUSION. The results of this study, in part, agree with the purported functions of neck muscles derived from anatomic location. This also was true for the few selected muscles that have been examined in human electromyographic studies. Neck muscle function and morphology can be studied at a detailed level using exercise-induced shifts in magnetic resonance images.

Penicillinase Studies on L-Phase Variants, G-Phase Variants, and Reverted Strains of Staphylococcus aureus

PubMed Central

Simon, Harold J.; Yin, Elaine Jong

1970-01-01

L-phase variants and small colony (G-phase) variants derived from penicillinase-producing Staphylococcus aureus strains were tested for penicillinase (beta lactamase) production. A refined variation of the modified Gots test for penicillinase was used to demonstrate penicillinase synthesis. Penicillinase synthesis was reduced in L-phase variants and G-phase variants when compared to parental strains. After reversion of variants to vegetative stages had been induced, revertants were tested for production of penicillinase, coagulase, and alpha hemolysin, mannitol fermentation, and pigment production, and comparisons were made between parent and reverted vegetative forms. All revertants of G-phase variants retained penicillinase activity. Most revertants of L-phase variants showed reduction or loss of penicillinase activity. Retention of coagulase activity, alpha hemolysin production, mannitol fermentation, pigmentation, and phage type varied among revertants. Images PMID:16557890

A novel thromboxane A2 receptor N42S variant results in reduced surface expression and platelet dysfunction.

PubMed

Nisar, Shaista P; Lordkipanidzé, Marie; Jones, Matthew L; Dawood, Ban; Murden, Sherina; Cunningham, Margaret R; Mumford, Andrew D; Wilde, Jonathan T; Watson, Steve P; Mundell, Stuart J; Lowe, Gillian C

2014-05-05

A small number of thromboxane receptor variants have been described in patients with a bleeding history that result in platelet dysfunction. We have identified a patient with a history of significant bleeding, who expresses a novel heterozygous thromboxane receptor variant that predicts an asparagine to serine substitution (N42S). This asparagine is conserved across all class A GPCRs, suggesting a vital role for receptor structure and function.We investigated the functional consequences of the TP receptor heterozygous N42S substitution by performing platelet function studies on platelet-rich plasma taken from the patient and healthy controls. We investigated the N42S mutation by expressing the wild-type (WT) and mutant receptor in human embryonic kidney (HEK) cells. Aggregation studies showed an ablation of arachidonic acid responses in the patient, whilst there was right-ward shift of the U46619 concentration response curve (CRC). Thromboxane generation was unaffected. Calcium mobilisation studies in cells lines showed a rightward shift of the U46619 CRC in N42S-expressing cells compared to WT. Radioligand binding studies revealed a reduction in BMax in platelets taken from the patient and in N42S-expressing cells, whilst cell studies confirmed poor surface expression. We have identified a novel thromboxane receptor variant, N42S, which results in platelet dysfunction due to reduced surface expression. It is associated with a significant bleeding history in the patient in whom it was identified. This is the first description of a naturally occurring variant that results in the substitution of this highly conserved residue and confirms the importance of this residue for correct GPCR function.

Real-Time Nonlocal Means-Based Despeckling.

PubMed

Breivik, Lars Hofsoy; Snare, Sten Roar; Steen, Erik Normann; Solberg, Anne H Schistad

2017-06-01

In this paper, we propose a multiscale nonlocal means-based despeckling method for medical ultrasound. The multiscale approach leads to large computational savings and improves despeckling results over single-scale iterative approaches. We present two variants of the method. The first, denoted multiscale nonlocal means (MNLM), yields uniform robust filtering of speckle both in structured and homogeneous regions. The second, denoted unnormalized MNLM (UMNLM), is more conservative in regions of structure assuring minimal disruption of salient image details. Due to the popularity of anisotropic diffusion-based methods in the despeckling literature, we review the connection between anisotropic diffusion and iterative variants of NLM. These iterative variants in turn relate to our multiscale variant. As part of our evaluation, we conduct a simulation study making use of ground truth phantoms generated from clinical B-mode ultrasound images. We evaluate our method against a set of popular methods from the despeckling literature on both fine and coarse speckle noise. In terms of computational efficiency, our method outperforms the other considered methods. Quantitatively on simulations and on a tissue-mimicking phantom, our method is found to be competitive with the state-of-the-art. On clinical B-mode images, our method is found to effectively smooth speckle while preserving low-contrast and highly localized salient image detail.

SU-F-J-32: Do We Need KV Imaging During CBCT Based Patient Set-Up for Lung Radiation Therapy?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gopal, A; Zhou, J; Prado, K

Purpose: To evaluate the role of 2D kilovoltage (kV) imaging to complement cone beam CT (CBCT) imaging in a shift threshold based image guided radiation therapy (IGRT) strategy for conventional lung radiotherapy. Methods: A retrospective study was conducted by analyzing IGRT couch shift trends for 15 patients that received lung radiation therapy to evaluate the benefit of performing orthogonal kV imaging prior to CBCT imaging. Herein, a shift threshold based IGRT protocol was applied, which would mandate additional CBCT verification if the applied patient shifts exceeded 3 mm to avoid intraobserver variability in CBCT registration and to confirm table shifts.more » For each patient, two IGRT strategies: kV + CBCT and CBCT alone, were compared and the recorded patient shifts were categorized into whether additional CBCT acquisition would have been mandated or not. The effectiveness of either strategy was gauged by the likelihood of needing additional CBCT imaging for accurate patient set-up. Results: The use of CBCT alone was 6 times more likely to require an additional CBCT than KV+CBCT, for a 3 mm shift threshold (88% vs 14%). The likelihood of additional CBCT verification generally increased with lower shift thresholds, and was significantly lower when kV+CBCT was used (7% with 5 mm shift threshold, 36% with 2 mm threshold), than with CBCT alone (61% with 5 mm shift threshold, 97% with 2 mm threshold). With CBCT alone, treatment time increased by 2.2 min and dose increased by 1.9 cGy per fraction on average due to additional CBCT with a 3mm shift threshold. Conclusion: The benefit of kV imaging to screen for gross misalignments led to more accurate CBCT based patient localization compared with using CBCT alone. The subsequently reduced need for additional CBCT verification will minimize treatment time and result in less overall patient imaging dose.« less

Improving response inhibition systems in frontotemporal dementia with citalopram

PubMed Central

Rittman, Timothy; Regenthal, Ralf; Robbins, Trevor W.; Rowe, James B.

2015-01-01

Disinhibition is a cardinal feature of the behavioural variant of frontotemporal dementia, presenting as impulsive and impetuous behaviours that are often difficult to manage. The options for symptomatic treatments are limited, but a potential target for therapy is the restoration of serotonergic function, which is both deficient in behavioural variant frontotemporal dementia and closely associated with inhibitory control. Based on preclinical studies and psychopharmacological interventions in other disorders, we predicted that inhibition would be associated with the right inferior frontal gyrus and dependent on serotonin. Using magnetoencephalography and electroencephalography of a Go-NoGo paradigm, we investigated the neural basis of behavioural disinhibition in behavioural variant frontotemporal dementia and the effect of selective serotonin reuptake inhibition on the neural systems for response inhibition. In a randomized double-blinded placebo-controlled crossover design study, 12 patients received either a single 30 mg dose of citalopram or placebo. Twenty age-matched healthy controls underwent the same magnetoencephalography/electroencephalography protocol on one session without citalopram, providing normative data for this task. In the control group, successful NoGo trials evoked two established indices of successful response inhibition: the NoGo-N2 and NoGo-P3. Both of these components were significantly attenuated by behavioural variant frontotemporal dementia. Cortical sources associated with successful inhibition in control subjects were identified in the right inferior frontal gyrus and anterior temporal lobe, which have been strongly associated with behavioural inhibition in imaging and lesion studies. These sources were impaired by behavioural variant frontotemporal dementia. Critically, citalopram enhanced the NoGo-P3 signal in patients, relative to placebo treatment, and increased the evoked response in the right inferior frontal gyrus. Voxel-based morphometry confirmed significant atrophy of inferior frontal gyrus, alongside insular, orbitofrontal and temporal cortex in our patient cohort. Together, these data suggest that the dysfunctional prefrontal cortical systems underlying response inhibition deficits in behavioural variant frontotemporal dementia can be partially restored by increasing serotonergic neurotransmission. The results support a translational neuroscience approach to impulsive neurological disorders and indicate the potential for symptomatic treatment of behavioural variant frontotemporal dementia including serotonergic strategies to improve disinhibition. PMID:26001387

Direct observation of dopant distribution in GaAs compound semiconductors using phase-shifting electron holography and Lorentz microscopy.

PubMed

Sasaki, Hirokazu; Otomo, Shinya; Minato, Ryuichiro; Yamamoto, Kazuo; Hirayama, Tsukasa

2014-06-01

Phase-shifting electron holography and Lorentz microscopy were used to map dopant distributions in GaAs compound semiconductors with step-like dopant concentration. Transmission electron microscope specimens were prepared using a triple beam focused ion beam (FIB) system, which combines a Ga ion beam, a scanning electron microscope, and an Ar ion beam to remove the FIB damaged layers. The p-n junctions were clearly observed in both under-focused and over-focused Lorentz microscopy images. A phase image was obtained by using a phase-shifting reconstruction method to simultaneously achieve high sensitivity and high spatial resolution. Differences in dopant concentrations between 1 × 10(19) cm(-3) and 1 × 10(18) cm(-3) regions were clearly observed by using phase-shifting electron holography. We also interpreted phase profiles quantitatively by considering inactive layers induced by ion implantation during the FIB process. The thickness of an inactive layer at different dopant concentration area can be measured from the phase image. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Bi-cubic interpolation for shift-free pan-sharpening

NASA Astrophysics Data System (ADS)

Aiazzi, Bruno; Baronti, Stefano; Selva, Massimo; Alparone, Luciano

2013-12-01

Most of pan-sharpening techniques require the re-sampling of the multi-spectral (MS) image for matching the size of the panchromatic (Pan) image, before the geometric details of Pan are injected into the MS image. This operation is usually performed in a separable fashion by means of symmetric digital low-pass filtering kernels with odd lengths that utilize piecewise local polynomials, typically implementing linear or cubic interpolation functions. Conversely, constant, i.e. nearest-neighbour, and quadratic kernels, implementing zero and two degree polynomials, respectively, introduce shifts in the magnified images, that are sub-pixel in the case of interpolation by an even factor, as it is the most usual case. However, in standard satellite systems, the point spread functions (PSF) of the MS and Pan instruments are centered in the middle of each pixel. Hence, commercial MS and Pan data products, whose scale ratio is an even number, are relatively shifted by an odd number of half pixels. Filters of even lengths may be exploited to compensate the half-pixel shifts between the MS and Pan sampling grids. In this paper, it is shown that separable polynomial interpolations of odd degrees are feasible with linear-phase kernels of even lengths. The major benefit is that bi-cubic interpolation, which is known to represent the best trade-off between performances and computational complexity, can be applied to commercial MS + Pan datasets, without the need of performing a further half-pixel registration after interpolation, to align the expanded MS with the Pan image.

Structural differences between bovine A(1) and A(2) β-casein alter micelle self-assembly and influence molecular chaperone activity.

PubMed

Raynes, J K; Day, L; Augustin, M A; Carver, J A

2015-04-01

Within each milk protein there are many individual protein variants and marked alterations to milk functionality can occur depending on the genetic variants of each protein present. Bovine A(1) and A(2) β-casein (β-CN) are 2 variants that contribute to differences in the gelation performance of milk. The A(1) and A(2) β-CN variants differ by a single AA, the substitution of histidine for proline at position 67. β-Casein not only participates in formation of the casein micelle but also forms an oligomeric micelle itself and functions as a molecular chaperone to prevent the aggregation of a wide range of proteins, including the other caseins. Micelle assembly of A(1) and A(2) β-CN was investigated using dynamic light scattering and small-angle X-ray scattering, whereas protein functionality was assessed using fluorescence techniques and molecular chaperone assays. The A(2) β-CN variant formed smaller micelles than A(1) β-CN, with the monomer-micelle equilibrium of A(2) β-CN being shifted toward the monomer. This shift most likely arose from structural differences between the 2 β-CN variants associated with the adoption of greater polyproline-II helix in A(2) β-CN and most likely led to enhanced chaperone activity of A(2) β-CN compared with A(1) β-CN. The difference in micelle assembly, and hence chaperone activity, may provide explain differences in the functionality of homozygous A(1) and A(2) milk. The results of this study highlight that substitution of even a single AA can significantly alter the properties of an intrinsically unstructured protein such as β-CN and, in this case, may have an effect on the functionality of milk. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Toward reducing immunogenicity of enzyme replacement therapy: altering the specificity of human β-glucuronidase to compensate for α-iduronidase deficiency.

PubMed

Chuang, Huai-Yao; Suen, Ching-Shu; Hwang, Ming-Jing; Roffler, Steve R

2015-11-01

Enzyme replacement therapy (ERT) is an effective treatment for many patients with lysosomal storage disorders caused by deficiency in enzymes involved in cell metabolism. However, immune responses that develop against the administered enzyme in some patients can hinder therapeutic efficacy and cause serious side effects. Here we investigated the feasibility of a general approach to decrease ERT immunogenicity by altering the specificity of a normal endogenous enzyme to compensate for a defective enzyme. We sought to identify human β-glucuronidase variants that display α-iduronidase activity, which is defective in mucopolysaccharidosis (MPS) type I patients. A human β-glucuronidase library was screened by the Enzyme Cleavable Surface-Tethered All-purpose Screen sYstem to isolate variants that exhibited 100-290-fold greater activity against the α-iduronidase substrate 4-methylumbelliferyl α-l-iduronide and 7900-24 500-fold enzymatic specificity shift when compared with wild-type β-glucuronidase. In vitro treatment of MPS I cells with the β-glucuronidase variants significantly restored lysosome appearance similar to treatment with α-iduronidase. Our study suggests that β-glucuronidase variants can be isolated to display α-iduronidase activity and produce significant phenotype improvement of MPS I cells. This strategy may represent a possible approach to produce enzymes that display therapeutic benefits with potentially less immunogenicity. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Genetic variation and dopamine D2 receptor availability: a systematic review and meta-analysis of human in vivo molecular imaging studies.

PubMed

Gluskin, B S; Mickey, B J

2016-03-01

The D2 dopamine receptor mediates neuropsychiatric symptoms and is a target of pharmacotherapy. Inter-individual variation of D2 receptor density is thought to influence disease risk and pharmacological response. Numerous molecular imaging studies have tested whether common genetic variants influence D2 receptor binding potential (BP) in humans, but demonstration of robust effects has been limited by small sample sizes. We performed a systematic search of published human in vivo molecular imaging studies to estimate effect sizes of common genetic variants on striatal D2 receptor BP. We identified 21 studies examining 19 variants in 11 genes. The most commonly studied variant was a single-nucleotide polymorphism in ANKK1 (rs1800497, Glu713Lys, also called 'Taq1A'). Fixed- and random-effects meta-analyses of this variant (5 studies, 194 subjects total) revealed that striatal BP was significantly and robustly lower among carriers of the minor allele (Lys713) relative to major allele homozygotes. The weighted standardized mean difference was -0.57 under the fixed-effect model (95% confidence interval=(-0.87, -0.27), P=0.0002). The normal relationship between rs1800497 and BP was not apparent among subjects with neuropsychiatric diseases. Significant associations with baseline striatal D2 receptor BP have been reported for four DRD2 variants (rs1079597, rs1076560, rs6277 and rs1799732) and a PER2 repeat polymorphism, but none have yet been tested in more than two independent samples. Our findings resolve apparent discrepancies in the literature and establish that rs1800497 robustly influences striatal D2 receptor availability. This genetic variant is likely to contribute to important individual differences in human striatal function, neuropsychiatric disease risk and pharmacological response.

[Work schedule of electric welders in heating microclimate].

PubMed

Sorokin, G A; Frolova, N M

2010-01-01

The authors present results of specified hygienically justified timing regulations for setting the variants of work and rest modes within electric welders shift, who work in various postures with variable visual strain while welding in heating microclimate.

Point spread function based classification of regions for linear digital tomosynthesis

NASA Astrophysics Data System (ADS)

Israni, Kenny; Avinash, Gopal; Li, Baojun

2007-03-01

In digital tomosynthesis, one of the limitations is the presence of out-of-plane blur due to the limited angle acquisition. The point spread function (PSF) characterizes blur in the imaging volume, and is shift-variant in tomosynthesis. The purpose of this research is to classify the tomosynthesis imaging volume into four different categories based on PSF-driven focus criteria. We considered linear tomosynthesis geometry and simple back projection algorithm for reconstruction. The three-dimensional PSF at every pixel in the imaging volume was determined. Intensity profiles were computed for every pixel by integrating the PSF-weighted intensities contained within the line segment defined by the PSF, at each slice. Classification rules based on these intensity profiles were used to categorize image regions. At background and low-frequency pixels, the derived intensity profiles were flat curves with relatively low and high maximum intensities respectively. At in-focus pixels, the maximum intensity of the profiles coincided with the PSF-weighted intensity of the pixel. At out-of-focus pixels, the PSF-weighted intensity of the pixel was always less than the maximum intensity of the profile. We validated our method using human observer classified regions as gold standard. Based on the computed and manual classifications, the mean sensitivity and specificity of the algorithm were 77+/-8.44% and 91+/-4.13% respectively (t=-0.64, p=0.56, DF=4). Such a classification algorithm may assist in mitigating out-of-focus blur from tomosynthesis image slices.

Quantitative refractive index distribution of single cell by combining phase-shifting interferometry and AFM imaging.

PubMed

Zhang, Qinnan; Zhong, Liyun; Tang, Ping; Yuan, Yingjie; Liu, Shengde; Tian, Jindong; Lu, Xiaoxu

2017-05-31

Cell refractive index, an intrinsic optical parameter, is closely correlated with the intracellular mass and concentration. By combining optical phase-shifting interferometry (PSI) and atomic force microscope (AFM) imaging, we constructed a label free, non-invasive and quantitative refractive index of single cell measurement system, in which the accurate phase map of single cell was retrieved with PSI technique and the cell morphology with nanoscale resolution was achieved with AFM imaging. Based on the proposed AFM/PSI system, we achieved quantitative refractive index distributions of single red blood cell and Jurkat cell, respectively. Further, the quantitative change of refractive index distribution during Daunorubicin (DNR)-induced Jurkat cell apoptosis was presented, and then the content changes of intracellular biochemical components were achieved. Importantly, these results were consistent with Raman spectral analysis, indicating that the proposed PSI/AFM based refractive index system is likely to become a useful tool for intracellular biochemical components analysis measurement, and this will facilitate its application for revealing cell structure and pathological state from a new perspective.

Facial Soft Tissue Measurement in Microgravity-induces Fluid Shifts

NASA Technical Reports Server (NTRS)

Marshburn, Thomas; Cole, Richard; Pavela, James; Garcia, Kathleen; Sargsyan, Ashot

2014-01-01

Fluid shifts are a well-known phenomenon in microgravity, and one result is facial edema. Objective measurement of tissue thickness in a standardized location could provide a correlate with the severity of the fluid shift. Previous studies of forehead tissue thickness (TTf) suggest that when exposed to environments that cause fluid shifts, including hypergravity, head-down tilt, and high-altitude/lowpressure, TTf changes in a consistent and measurable fashion. However, the technique in past studies is not well described or standardized. The International Space Station (ISS) houses an ultrasound (US) system capable of accurate sub-millimeter measurements of TTf. We undertook to measure TTf during long-duration space flight using a new accurate, repeatable and transferable technique. Methods: In-flight and post-flight B-mode ultrasound images of a single astronaut's facial soft tissues were obtained using a Vivid-q US system with a 12L-RS high-frequency linear array probe (General Electric, USA). Strictly mid-sagittal images were obtained involving the lower frontal bone, the nasofrontal angle, and the osseo-cartilaginous junction below. Single images were chosen for comparison that contained identical views of the bony landmarks and identical acoustical interface between the probe and skin. Using Gingko CADx DICOM viewing software, soft tissue thickness was measured at a right angle to the most prominent point of the inferior frontal bone to the epidermis. Four independent thickness measurements were made. Conclusions: Forehead tissue thickness measurement by ultrasound in microgravity is feasible, and our data suggest a decrease in tissue thickness upon return from microgravity environment, which is likely related to the cessation of fluid shifts. Further study is warranted to standardize the technique with regard to the individual variability of the local anatomy in this area.

CRAWview: for viewing splicing variation, gene families, and polymorphism in clusters of ESTs and full-length sequences.

PubMed

Chou, A; Burke, J

1999-05-01

DNA sequence clustering has become a valuable method in support of gene discovery and gene expression analysis. Our interest lies in leveraging the sequence diversity within clusters of expressed sequence tags (ESTs) to model gene structure for the study of gene variants that arise from, among other things, alternative mRNA splicing, polymorphism, and divergence after gene duplication, fusion, and translocation events. In previous work, CRAW was developed to discover gene variants from assembled clusters of ESTs. Most importantly, novel gene features (the differing units between gene variants, for example alternative exons, polymorphisms, transposable elements, etc.) that are specialized to tissue, disease, population, or developmental states can be identified when these tools collate DNA source information with gene variant discrimination. While the goal is complete automation of novel feature and gene variant detection, current methods are far from perfect and hence the development of effective tools for visualization and exploratory data analysis are of paramount importance in the process of sifting through candidate genes and validating targets. We present CRAWview, a Java based visualization extension to CRAW. Features that vary between gene forms are displayed using an automatically generated color coded index. The reporting format of CRAWview gives a brief, high level summary report to display overlap and divergence within clusters of sequences as well as the ability to 'drill down' and see detailed information concerning regions of interest. Additionally, the alignment viewing and editing capabilities of CRAWview make it possible to interactively correct frame-shifts and otherwise edit cluster assemblies. We have implemented CRAWview as a Java application across windows NT/95 and UNIX platforms. A beta version of CRAWview will be freely available to academic users from Pangea Systems (http://www.pangeasystems.com). Contact :

Improving the photostability of bright monomeric orange and red fluorescent proteins.

PubMed

Shaner, Nathan C; Lin, Michael Z; McKeown, Michael R; Steinbach, Paul A; Hazelwood, Kristin L; Davidson, Michael W; Tsien, Roger Y

2008-06-01

All organic fluorophores undergo irreversible photobleaching during prolonged illumination. Although fluorescent proteins typically bleach at a substantially slower rate than many small-molecule dyes, in many cases the lack of sufficient photostability remains an important limiting factor for experiments requiring large numbers of images of single cells. Screening methods focusing solely on brightness or wavelength are highly effective in optimizing both properties, but the absence of selective pressure for photostability in such screens leads to unpredictable photobleaching behavior in the resulting fluorescent proteins. Here we describe an assay for screening libraries of fluorescent proteins for enhanced photostability. With this assay, we developed highly photostable variants of mOrange (a wavelength-shifted monomeric derivative of DsRed from Discosoma sp.) and TagRFP (a monomeric derivative of eqFP578 from Entacmaea quadricolor) that maintain most of the beneficial qualities of the original proteins and perform as reliably as Aequorea victoria GFP derivatives in fusion constructs.

Space-variant restoration of images degraded by camera motion blur.

PubMed

Sorel, Michal; Flusser, Jan

2008-02-01

We examine the problem of restoration from multiple images degraded by camera motion blur. We consider scenes with significant depth variations resulting in space-variant blur. The proposed algorithm can be applied if the camera moves along an arbitrary curve parallel to the image plane, without any rotations. The knowledge of camera trajectory and camera parameters is not necessary. At the input, the user selects a region where depth variations are negligible. The algorithm belongs to the group of variational methods that estimate simultaneously a sharp image and a depth map, based on the minimization of a cost functional. To initialize the minimization, it uses an auxiliary window-based depth estimation algorithm. Feasibility of the algorithm is demonstrated by three experiments with real images.

A Distinct Phenotype of Eyes Shut Homolog (EYS)-Retinitis Pigmentosa Is Associated With Variants Near the C-Terminus.

PubMed

Sengillo, Jesse D; Lee, Winston; Nagasaki, Takayuki; Schuerch, Kaspar; Yannuzzi, Lawrence A; Freund, K Bailey; Sparrow, Janet R; Allikmets, Rando; Tsang, Stephen H

2018-06-01

Mutations in the eyes shut homolog (EYS) gene are a frequent cause of autosomal recessive retinitis pigmentosa (arRP). This study used multimodal retinal imaging to elucidate genotype-phenotype correlations in EYS-related RP (EYS-RP). Cross-sectional study. Multimodal retinal imaging and electrophysiologic testing were assessed for 16 patients with genetic confirmation of EYS-RP. A total of 27 unique EYS variants were identified in 16 patients. Seven patients presented with an unusual crescent-shaped hyperautofluorescent (hyperAF) ring on fundus autofluorescence (FAF) imaging encompassing a large nasal-superior area of the posterior pole. Three patients had a typical circular or oval perifoveal hyperAF ring and 6 patients had no hyperAF ring. Spectral-domain (SD) and en face optical coherence tomography (OCT) showed preserved ellipsoid zone and retinal thickness spatially corresponding to areas within the hyperAF rings. Eleven patients presented with a rod-cone dystrophy on full-field electroretinogram (ffERG), 1 patient presented with cone-rod dystrophy, and 4 patients did not undergo ffERG testing. A significant spatial association was found between EYS variant position and FAF phenotype, with variants occurring at a nucleotide position greater than GRCh37 6:65300137 (c.5617C) being more associated with patients exhibiting hyperAF rings at presentation. EYS-RP is a heterogeneous manifestation. Variants occurring in positions closer to the C-terminus of EYS are more common in patients presenting with hyperAF rings on FAF imaging. Copyright © 2018 Elsevier Inc. All rights reserved.

Two-Color Laser Speckle Shift Strain Measurement System

NASA Technical Reports Server (NTRS)

Tuma, Margaret L.; Krasowski, Michael J.; Oberle, Lawrence G.; Greer, Lawrence C., III; Spina, Daniel; Barranger, John

1996-01-01

A two color laser speckle shift strain measurement system based on the technique of Yamaguchi was designed. The dual wavelength light output from an Argon Ion laser was coupled into two separate single-mode optical fibers (patchcords). The output of the patchcords is incident on the test specimen (here a structural fiber). Strain on the fiber, in one direction, is produced using an Instron 4502. Shifting interference patterns or speckle patterns will be detected at real-time rates using 2 CCD cameras with image processing performed by a hardware correlator. Strain detected in fibers with diameters from 21 microns to 143 microns is expected to be resolved to 15 mu epsilon. This system was designed to be compact and robust and does not require surface preparation of the structural fibers.

Unsupervised Segmentation of Head Tissues from Multi-modal MR Images for EEG Source Localization.

PubMed

Mahmood, Qaiser; Chodorowski, Artur; Mehnert, Andrew; Gellermann, Johanna; Persson, Mikael

2015-08-01

In this paper, we present and evaluate an automatic unsupervised segmentation method, hierarchical segmentation approach (HSA)-Bayesian-based adaptive mean shift (BAMS), for use in the construction of a patient-specific head conductivity model for electroencephalography (EEG) source localization. It is based on a HSA and BAMS for segmenting the tissues from multi-modal magnetic resonance (MR) head images. The evaluation of the proposed method was done both directly in terms of segmentation accuracy and indirectly in terms of source localization accuracy. The direct evaluation was performed relative to a commonly used reference method brain extraction tool (BET)-FMRIB's automated segmentation tool (FAST) and four variants of the HSA using both synthetic data and real data from ten subjects. The synthetic data includes multiple realizations of four different noise levels and several realizations of typical noise with a 20% bias field level. The Dice index and Hausdorff distance were used to measure the segmentation accuracy. The indirect evaluation was performed relative to the reference method BET-FAST using synthetic two-dimensional (2D) multimodal magnetic resonance (MR) data with 3% noise and synthetic EEG (generated for a prescribed source). The source localization accuracy was determined in terms of localization error and relative error of potential. The experimental results demonstrate the efficacy of HSA-BAMS, its robustness to noise and the bias field, and that it provides better segmentation accuracy than the reference method and variants of the HSA. They also show that it leads to a more accurate localization accuracy than the commonly used reference method and suggest that it has potential as a surrogate for expert manual segmentation for the EEG source localization problem.

Two-color temporal focusing multiphoton excitation imaging with tunable-wavelength excitation

NASA Astrophysics Data System (ADS)

Lien, Chi-Hsiang; Abrigo, Gerald; Chen, Pei-Hsuan; Chien, Fan-Ching

2017-02-01

Wavelength tunable temporal focusing multiphoton excitation microscopy (TFMPEM) is conducted to visualize optical sectioning images of multiple fluorophore-labeled specimens through the optimal two-photon excitation (TPE) of each type of fluorophore. The tunable range of excitation wavelength was determined by the groove density of the grating, the diffraction angle, the focal length of lenses, and the shifting distance of the first lens in the beam expander. Based on a consideration of the trade-off between the tunable-wavelength range and axial resolution of temporal focusing multiphoton excitation imaging, the presented system demonstrated a tunable-wavelength range from 770 to 920 nm using a diffraction grating with groove density of 830 lines/mm. TPE fluorescence imaging examination of a fluorescent thin film indicated that the width of the axial confined excitation was 3.0±0.7 μm and the shifting distance of the temporal focal plane was less than 0.95 μm within the presented wavelength tunable range. Fast different wavelength excitation and three-dimensionally rendered imaging of Hela cell mitochondria and cytoskeletons and mouse muscle fibers were demonstrated. Significantly, the proposed system can improve the quality of two-color TFMPEM images through different excitation wavelengths to obtain higher-quality fluorescent signals in multiple-fluorophore measurements.

Single-element ultrasound transducer for combined vessel localization and ablation.

PubMed

Chen, Wen-Shiang; Shen, Che-Chou; Wang, Jen-Chieh; Ko, Chung-Ting; Liu, Hao-Li; Ho, Ming-Chih; Chen, Chiung-Nien; Yeh, Chih-Kuang

2011-04-01

This report describes a system that utilizes a single high-intensity focused ultrasound (HIFU) transducer for both the localization and ablation of arteries with internal diameters of 0.5 and 1.3 mm. In vitro and in vivo tests were performed to demonstrate both the imaging and ablation functionalities of this system. For imaging mode, pulsed acoustic waves (3 cycles for in vitro and 10 cycles for in vivo tests, 2 MPa peak pressure) were emitted from the 2-MHz HIFU transducer, and the backscattered ultrasonic signal was collected by the same transducer to calculate Doppler shifts in the target region. The maximum signal amplitude of the Doppler shift was used to determine the location of the target vessel. The operation mode was then switched to the therapeutic mode and vessel occlusion was successfully produced by high-intensity continuous HIFU waves (12 MPa) for 60 s. The system was then switched back to imaging mode for residual flow to determine the need for a second ablation treatment. The new system might be used to target and occlude unwanted vessels such as vasculature around tumors, and to help with tumor destruction. © 2011 IEEE

Embossed radiography utilizing energy subtraction.

PubMed

Osawa, Akihiro; Watanabe, Manabu; Sato, Eiichi; Matsukiyo, Hiroshi; Enomoto, Toshiyuki; Nagao, Jiro; Abderyim, Purkhet; Aizawa, Katsuo; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Ehara, Shigeru; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

2009-01-01

Currently, it is difficult to carry out refraction-contrast radiography by using a conventional X-ray generator. Thus, we developed an embossed radiography system utilizing dual-energy subtraction for decreasing the absorption contrast in unnecessary regions, and the contrast resolution of a target region was increased by use of image-shifting subtraction and a linear-contrast system in a flat panel detector (FPD). The X-ray generator had a 100-microm-focus tube. Energy subtraction was performed at tube voltages of 45 and 65 kV, a tube current of 0.50 mA, and an X-ray exposure time of 5.0 s. A 1.0-mm-thick aluminum filter was used for absorbing low-photon-energy bremsstrahlung X-rays. Embossed radiography was achieved with cohesion imaging by use of the FPD with pixel sizes of 48 x 48 microm, and the shifting dimension of an object in the horizontal direction ranged from 100 to 200 microm. At a shifting distance of 100 mum, the spatial resolutions in the horizontal and vertical directions measured with a lead test chart were both 83 microm. In embossed radiography of non-living animals, we obtained high-contrast embossed images of fine bones, gadolinium oxide particles in the kidney, and coronary arteries approximately 100 microm in diameter.

Regional fringe analysis for improving depth measurement in phase-shifting fringe projection profilometry

NASA Astrophysics Data System (ADS)

Chien, Kuang-Che Chang; Tu, Han-Yen; Hsieh, Ching-Huang; Cheng, Chau-Jern; Chang, Chun-Yen

2018-01-01

This study proposes a regional fringe analysis (RFA) method to detect the regions of a target object in captured shifted images to improve depth measurement in phase-shifting fringe projection profilometry (PS-FPP). In the RFA method, region-based segmentation is exploited to segment the de-fringed image of a target object, and a multi-level fuzzy-based classification with five presented features is used to analyze and discriminate the regions of an object from the segmented regions, which were associated with explicit fringe information. Then, in the experiment, the performance of the proposed method is tested and evaluated on 26 test cases made of five types of materials. The qualitative and quantitative results demonstrate that the proposed RFA method can effectively detect the desired regions of an object to improve depth measurement in the PS-FPP system.

Threshold secret sharing scheme based on phase-shifting interferometry.

PubMed

Deng, Xiaopeng; Shi, Zhengang; Wen, Wei

2016-11-01

We propose a new method for secret image sharing with the (3,N) threshold scheme based on phase-shifting interferometry. The secret image, which is multiplied with an encryption key in advance, is first encrypted by using Fourier transformation. Then, the encoded image is shared into N shadow images based on the recording principle of phase-shifting interferometry. Based on the reconstruction principle of phase-shifting interferometry, any three or more shadow images can retrieve the secret image, while any two or fewer shadow images cannot obtain any information of the secret image. Thus, a (3,N) threshold secret sharing scheme can be implemented. Compared with our previously reported method, the algorithm of this paper is suited for not only a binary image but also a gray-scale image. Moreover, the proposed algorithm can obtain a larger threshold value t. Simulation results are presented to demonstrate the feasibility of the proposed method.

Haemoglobin Pierre-Benite--a high affinity variant associated with relative polycythaemia.

PubMed

Beard, M E; Potter, H C; Spearing, R L; Brennan, S O

2001-12-01

This is the second reported example of Hb Pierre--Benite (beta90 Glu-->Asp). This mutation is associated with increased oxygen affinity and polycythaemia. No instability was found and there was no charge shift detected by cellulose acetate electrophoresis at pH 8.3. The mutation was however, clearly indicated by electrospray ionization mass spectrometry (ESI MS), which showed an abnormal beta chain with a 14 Da decrease in mass. Blood volume studies documented a relative rather than a true polycythaemia and this finding has been reported in at least two other high affinity haemoglobin variants--Hb Heathrow and Hb Rahere. This finding led to delay in diagnosis because high oxygen affinity variants are conventionally considered to cause a true polycythaemia.

Automatic extraction of nuclei centroids of mouse embryonic cells from fluorescence microscopy images.

PubMed

Bashar, Md Khayrul; Komatsu, Koji; Fujimori, Toshihiko; Kobayashi, Tetsuya J

2012-01-01

Accurate identification of cell nuclei and their tracking using three dimensional (3D) microscopic images is a demanding task in many biological studies. Manual identification of nuclei centroids from images is an error-prone task, sometimes impossible to accomplish due to low contrast and the presence of noise. Nonetheless, only a few methods are available for 3D bioimaging applications, which sharply contrast with 2D analysis, where many methods already exist. In addition, most methods essentially adopt segmentation for which a reliable solution is still unknown, especially for 3D bio-images having juxtaposed cells. In this work, we propose a new method that can directly extract nuclei centroids from fluorescence microscopy images. This method involves three steps: (i) Pre-processing, (ii) Local enhancement, and (iii) Centroid extraction. The first step includes two variations: first variation (Variant-1) uses the whole 3D pre-processed image, whereas the second one (Variant-2) modifies the preprocessed image to the candidate regions or the candidate hybrid image for further processing. At the second step, a multiscale cube filtering is employed in order to locally enhance the pre-processed image. Centroid extraction in the third step consists of three stages. In Stage-1, we compute a local characteristic ratio at every voxel and extract local maxima regions as candidate centroids using a ratio threshold. Stage-2 processing removes spurious centroids from Stage-1 results by analyzing shapes of intensity profiles from the enhanced image. An iterative procedure based on the nearest neighborhood principle is then proposed to combine if there are fragmented nuclei. Both qualitative and quantitative analyses on a set of 100 images of 3D mouse embryo are performed. Investigations reveal a promising achievement of the technique presented in terms of average sensitivity and precision (i.e., 88.04% and 91.30% for Variant-1; 86.19% and 95.00% for Variant-2), when compared with an existing method (86.06% and 90.11%), originally developed for analyzing C. elegans images.

Phase rainbow refractometry for accurate droplet variation characterization.

PubMed

Wu, Yingchun; Promvongsa, Jantarat; Saengkaew, Sawitree; Wu, Xuecheng; Chen, Jia; Gréhan, Gérard

2016-10-15

We developed a one-dimensional phase rainbow refractometer for the accurate trans-dimensional measurements of droplet size on the micrometer scale as well as the tiny droplet diameter variations at the nanoscale. The dependence of the phase shift of the rainbow ripple structures on the droplet variations is revealed. The phase-shifting rainbow image is recorded by a telecentric one-dimensional rainbow imaging system. Experiments on the evaporating monodispersed droplet stream show that the phase rainbow refractometer can measure the tiny droplet diameter changes down to tens of nanometers. This one-dimensional phase rainbow refractometer is capable of measuring the droplet refractive index and diameter, as well as variations.

MTF evaluation of in-line phase contrast imaging system

NASA Astrophysics Data System (ADS)

Sun, Xiaoran; Gao, Feng; Zhao, Huijuan; Zhang, Limin; Li, Jiao; Zhou, Zhongxing

2017-02-01

X-ray phase contrast imaging (XPCI) is a novel method that exploits the phase shift for the incident X-ray to form an image. Various XPCI methods have been proposed, among which, in-line phase contrast imaging (IL-PCI) is regarded as one of the most promising clinical methods. The contrast of the interface is enhanced due to the introduction of the boundary fringes in XPCI, thus it is generally used to evaluate the image quality of XPCI. But the contrast is a comprehensive index and it does not reflect the information of image quality in the frequency range. The modulation transfer function (MTF), which is the Fourier transform of the system point spread function, is recognized as the metric to characterize the spatial response of conventional X-ray imaging system. In this work, MTF is introduced into the image quality evaluation of the IL-PCI system. Numerous simulations based on Fresnel - Kirchhoff diffraction theory are performed with varying system settings and the corresponding MTFs were calculated for comparison. The results show that MTF can provide more comprehensive information of image quality comparing to contrast in IL-PCI.

Impact of stride-coupled gaze shifts of walking blowflies on the neuronal representation of visual targets

PubMed Central

Kress, Daniel; Egelhaaf, Martin

2014-01-01

During locomotion animals rely heavily on visual cues gained from the environment to guide their behavior. Examples are basic behaviors like collision avoidance or the approach to a goal. The saccadic gaze strategy of flying flies, which separates translational from rotational phases of locomotion, has been suggested to facilitate the extraction of environmental information, because only image flow evoked by translational self-motion contains relevant distance information about the surrounding world. In contrast to the translational phases of flight during which gaze direction is kept largely constant, walking flies experience continuous rotational image flow that is coupled to their stride-cycle. The consequences of these self-produced image shifts for the extraction of environmental information are still unclear. To assess the impact of stride-coupled image shifts on visual information processing, we performed electrophysiological recordings from the HSE cell, a motion sensitive wide-field neuron in the blowfly visual system. This cell has been concluded to play a key role in mediating optomotor behavior, self-motion estimation and spatial information processing. We used visual stimuli that were based on the visual input experienced by walking blowflies while approaching a black vertical bar. The response of HSE to these stimuli was dominated by periodic membrane potential fluctuations evoked by stride-coupled image shifts. Nevertheless, during the approach the cell’s response contained information about the bar and its background. The response components evoked by the bar were larger than the responses to its background, especially during the last phase of the approach. However, as revealed by targeted modifications of the visual input during walking, the extraction of distance information on the basis of HSE responses is much impaired by stride-coupled retinal image shifts. Possible mechanisms that may cope with these stride-coupled responses are discussed. PMID:25309362

Optical image encryption by random shifting in fractional Fourier domains

NASA Astrophysics Data System (ADS)

Hennelly, B.; Sheridan, J. T.

2003-02-01

A number of methods have recently been proposed in the literature for the encryption of two-dimensional information by use of optical systems based on the fractional Fourier transform. Typically, these methods require random phase screen keys for decrypting the data, which must be stored at the receiver and must be carefully aligned with the received encrypted data. A new technique based on a random shifting, or jigsaw, algorithm is proposed. This method does not require the use of phase keys. The image is encrypted by juxtaposition of sections of the image in fractional Fourier domains. The new method has been compared with existing methods and shows comparable or superior robustness to blind decryption. Optical implementation is discussed, and the sensitivity of the various encryption keys to blind decryption is examined.

Advanced biologically plausible algorithms for low-level image processing

NASA Astrophysics Data System (ADS)

Gusakova, Valentina I.; Podladchikova, Lubov N.; Shaposhnikov, Dmitry G.; Markin, Sergey N.; Golovan, Alexander V.; Lee, Seong-Whan

1999-08-01

At present, in computer vision, the approach based on modeling the biological vision mechanisms is extensively developed. However, up to now, real world image processing has no effective solution in frameworks of both biologically inspired and conventional approaches. Evidently, new algorithms and system architectures based on advanced biological motivation should be developed for solution of computational problems related to this visual task. Basic problems that should be solved for creation of effective artificial visual system to process real world imags are a search for new algorithms of low-level image processing that, in a great extent, determine system performance. In the present paper, the result of psychophysical experiments and several advanced biologically motivated algorithms for low-level processing are presented. These algorithms are based on local space-variant filter, context encoding visual information presented in the center of input window, and automatic detection of perceptually important image fragments. The core of latter algorithm are using local feature conjunctions such as noncolinear oriented segment and composite feature map formation. Developed algorithms were integrated into foveal active vision model, the MARR. It is supposed that proposed algorithms may significantly improve model performance while real world image processing during memorizing, search, and recognition.

Nonlinear Time-Variant Response in an Avalanche Photodiode Array Based Laser Detection and Ranging System

DTIC Science & Technology

2007-03-01

the system is treated in a gray-box manner, with limited known parameters. The analytical approach which follows was used to identify the deviations be...effect spherical aberration, coma and astigmatism is to blur the image by introducing light from outside each pixel’s IFOV. Petzval field curvature and...difference between the two records is not the linear difference of the incident light levels. Even dark current subtraction must be treated with caution

SU-F-J-188: Clinical Implementation of in Room Mobile CT for Image Guided Proton Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, H; Wu, R; Poenisch, F

Purpose: To implement soft-tissue image-guided proton therapy using inroom mobile CT. Methods: Anthropomorphic phantom was first used to determine the setup accuracy using in- room mobile CT. Laser and bbs were used for the initial setup (marked isocenter). CT data was then acquired with in-room mobile CT (daily CT). The shift between the marked isocenter and the planned isocenter (final isocenter) was determined from the daily CT using in-house Computer Assisted Targeting (CAT) software. Orthogonal DRRs of the day was also generated from the daily CT. The phantom was then transferred on the treatment couch top to the treatment machinemore » using a transportation system, and again aligned to the marked isocenter. Couch shifts were made to align the phantom to the final isocenter using the shifts as determined using the CAT software, and verified using orthogonal X-ray images with the daily DRRs. Results: Phantom data suggests that following the setup procedure as described above, targeting accuracy could be within 1 mm. Patient data are being acquired and analyzed. Conclusion: In-room mobile CT is capable of providing soft-tissue image-guided proton therapy.« less

A homozygous transthyretin variant associated with senile systemic amyloidosis: evidence for a late-onset disease of genetic etiology.

PubMed Central

Jacobson, D R; Gorevic, P D; Buxbaum, J N

1990-01-01

Senile systemic amyloidosis (SSA) is a late-onset disease characterized by deposition of amyloid fibrils containing transthyretin (TTR). Amino acid sequencing of protein isolated from the amyloid fibrils of a patient with SSA identified TTR containing a position - 122 isoleucine-for-valine substitution. This change led to the prediction of a genomic G-to-A transition, destroying an MaeIII restriction site. We confirmed the presence of the variant DNA fragment both by Southern blotting and by visualization of MaeIII digests of DNA amplified around codon 122, by using the polymerase chain reaction. The patient's DNA was entirely resistant to MaeIII cleavage; therefore, only the mutant sequence was present. DNA from none of either 24 controls or six other SSA patients contained the variant. Quantitative Southern blotting demonstrated that the patient's DNA contained two copies of the TTR gene per genome; the mutation was therefore homozygous rather than hemizygous. In the present case, the homozygous mutation TTR (122 Val----Ile) is associated with SSA, a finding which is consistent with autosomal recessive inheritance of this condition. Images Figure 2 Figure 4 Figure 5 Figure 6 Figure 7 PMID:2349941

Parenchymal Neurocutaneous Melanosis in Association with Intraventricular Dermoid and Dandy-Walker Variant: A Case Report

PubMed Central

Won, Yoo Dong; Kim, Ki Tae; Chang, Eun Deok; Huh, Pil Woo

2006-01-01

Neurocutaneous melanosis (NCM) is a rare congenital disease that is characterized by the presence of large or multiple congenital melanocytic nevi and melanotic lesions of the central nervous system. We report here on the CT and MR imaging findings of an unusual case of NCM that was associated with intraventricular dermoid and Dandy-Walker malformation. PMID:16799276

TARDEC Update for TTCP

DTIC Science & Technology

2009-04-01

09 COL Kevin Peterson Principal Deputy Program Manager Joint MRAP Vehicle Program 17 MRAP Variant Overview FP COUGAR CAT I (FPII CAT I) MaxxPro BAE...distribution unlimited 13. SUPPLEMENTARY NOTES Presented at the TTCP LND TP3 Annual Meeting and Task Workshop Manned and Unmanned Ground Vehicle Systems, 23...28 April 2009, Suffield, Alberta, Canada, The original document contains color images. 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY

Excitation and characterization of image potential state electrons on quasi-free-standing graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Yi; Li, Yunzhe; Sadowski, Jerzy T.

We investigate the band structure of image potential states in quasi-free-standing graphene (QFG) monolayer islands using angle-resolved two-photon-photoemission spectroscopy. Direct probing by low-energy electron diffraction shows that QFG is formed following oxygen intercalation into the graphene-Ir(111) interface. Despite the apparent decoupling of the monolayer graphene from the Ir substrate, we find that the binding energy of the n = 1 image potential state on these QFG islands increases by 0.17 eV, as compared to the original Gr/Ir(111) interface. We use calculations based on density-functional theory to construct an empirical, one-dimensional potential that quantitatively reproduces the image potential state binding energymore » and links the changes in the interface structure to the shift in energy. Specifically, two factors contribute comparably to this energy shift: a deeper potential well arising from the presence of intercalated oxygen adatoms and a wider potential well associated with the increase in the graphene-Ir distance. While image potential states have not been observed previously on QFG by photoemission, our paper now demonstrates that they may be strongly excited in a well-defined QFG system produced by oxygen intercalation. Finally, this opens an opportunity for studying the surface electron dynamics in QFG systems, beyond those found in typical nonintercalated graphene-on-substrate systems.« less

Excitation and characterization of image potential state electrons on quasi-free-standing graphene

DOE PAGES

Lin, Yi; Li, Yunzhe; Sadowski, Jerzy T.; ...

2018-04-09

We investigate the band structure of image potential states in quasi-free-standing graphene (QFG) monolayer islands using angle-resolved two-photon-photoemission spectroscopy. Direct probing by low-energy electron diffraction shows that QFG is formed following oxygen intercalation into the graphene-Ir(111) interface. Despite the apparent decoupling of the monolayer graphene from the Ir substrate, we find that the binding energy of the n = 1 image potential state on these QFG islands increases by 0.17 eV, as compared to the original Gr/Ir(111) interface. We use calculations based on density-functional theory to construct an empirical, one-dimensional potential that quantitatively reproduces the image potential state binding energymore » and links the changes in the interface structure to the shift in energy. Specifically, two factors contribute comparably to this energy shift: a deeper potential well arising from the presence of intercalated oxygen adatoms and a wider potential well associated with the increase in the graphene-Ir distance. While image potential states have not been observed previously on QFG by photoemission, our paper now demonstrates that they may be strongly excited in a well-defined QFG system produced by oxygen intercalation. Finally, this opens an opportunity for studying the surface electron dynamics in QFG systems, beyond those found in typical nonintercalated graphene-on-substrate systems.« less

Genetic study of multimodal imaging Alzheimer's disease progression score implicates novel loci.

PubMed

Scelsi, Marzia A; Khan, Raiyan R; Lorenzi, Marco; Christopher, Leigh; Greicius, Michael D; Schott, Jonathan M; Ourselin, Sebastien; Altmann, Andre

2018-05-30

Identifying genetic risk factors underpinning different aspects of Alzheimer's disease has the potential to provide important insights into pathogenesis. Moving away from simple case-control definitions, there is considerable interest in using quantitative endophenotypes, such as those derived from imaging as outcome measures. Previous genome-wide association studies of imaging-derived biomarkers in sporadic late-onset Alzheimer's disease focused only on phenotypes derived from single imaging modalities. In contrast, we computed a novel multi-modal neuroimaging phenotype comprising cortical amyloid burden and bilateral hippocampal volume. Both imaging biomarkers were used as input to a disease progression modelling algorithm, which estimates the biomarkers' long-term evolution curves from population-based longitudinal data. Among other parameters, the algorithm computes the shift in time required to optimally align a subjects' biomarker trajectories with these population curves. This time shift serves as a disease progression score and it was used as a quantitative trait in a discovery genome-wide association study with n = 944 subjects from the Alzheimer's Disease Neuroimaging Initiative database diagnosed as Alzheimer's disease, mild cognitive impairment or healthy at the time of imaging. We identified a genome-wide significant locus implicating LCORL (rs6850306, chromosome 4; P = 1.03 × 10-8). The top variant rs6850306 was found to act as an expression quantitative trait locus for LCORL in brain tissue. The clinical role of rs6850306 in conversion from healthy ageing to mild cognitive impairment or Alzheimer's disease was further validated in an independent cohort comprising healthy, older subjects from the National Alzheimer's Coordinating Center database. Specifically, possession of a minor allele at rs6850306 was protective against conversion from mild cognitive impairment to Alzheimer's disease in the National Alzheimer's Coordinating Center cohort (hazard ratio = 0.593, 95% confidence interval = 0.387-0.907, n = 911, PBonf = 0.032), in keeping with the negative direction of effect reported in the genome-wide association study (βdisease progression score = -0.07 ± 0.01). The implicated locus is linked to genes with known connections to Alzheimer's disease pathophysiology and other neurodegenerative diseases. Using multimodal imaging phenotypes in association studies may assist in unveiling the genetic drivers of the onset and progression of complex diseases.

NO PLIF Imaging in the CUBRC 48-inch Shock Tunnel

DTIC Science & Technology

2012-01-01

Exp Fluids (2012) 53:1637-1646 OOI 10.1007/s00348-012-1381-6 RESEARCH ARTICLE NO PLIF imaging in the CUBRC 48-inch shock tunnel N. Jiang· J...Center’s (CUBRC) 48-inch Mach 9 hypervelocity shock tunnel using a pulse burst laser-based high frame rate imaging system. Sequences of up to ten images...2002) have been performed in the Australia National University’s T2 free- piston shock tunnel . More recently, two-component Doppler- shift-based

Random Plant Viral Variants Attain Temporal Advantages During Systemic Infections and in Turn Resist other Variants of the Same Virus.

PubMed

Zhang, Xiao-Feng; Guo, Jiangbo; Zhang, Xiuchun; Meulia, Tea; Paul, Pierce; Madden, Laurence V; Li, Dawei; Qu, Feng

2015-10-20

Infection of plants with viruses containing multiple variants frequently leads to dominance by a few random variants in the systemically infected leaves (SLs), for which a plausible explanation is lacking. We show here that SL dominance by a given viral variant is adequately explained by its fortuitous lead in systemic spread, coupled with its resistance to superinfection by other variants. We analyzed the fate of a multi-variant turnip crinkle virus (TCV) population in Arabidopsis and N. benthamiana plants. Both wild-type and RNA silencing-defective plants displayed a similar pattern of random dominance by a few variant genotypes, thus discounting a prominent role for RNA silencing. When introduced to plants sequentially as two subpopulations, a twelve-hour head-start was sufficient for the first set to dominate. Finally, SLs of TCV-infected plants became highly resistant to secondary invasions of another TCV variant. We propose that random distribution of variant foci on inoculated leaves allows different variants to lead systemic movement in different plants. The leading variants then colonize large areas of SLs, and resist the superinfection of lagging variants in the same areas. In conclusion, superinfection resistance is the primary driver of random enrichment of viral variants in systemically infected plants.

The x-ray light valve: a potentially low-cost, digital radiographic imaging system--a liquid crystal cell design for chest radiography.

PubMed

Szeto, Timothy C; Webster, Christie Ann; Koprinarov, Ivaylo; Rowlands, J A

2008-03-01

Digital x-ray radiographic systems are desirable as they offer high quality images which can be processed, transferred, and stored without secondary steps. However, current clinical systems are extraordinarily expensive in comparison to film-based systems. Thus, there is a need for an economical digital imaging system for general radiology. The x-ray light valve (XLV) is a novel digital x-ray detector concept with the potential for high image quality and low cost. The XLV is comprised of a photoconductive detector layer and liquid crystal (LC) cell physically coupled in a sandwich structure. Upon exposure to x rays, charge is collected at the surface of the photoconductor, causing a change in the reflective properties of the LC cell. The visible image so formed can subsequently be digitized with an optical scanner. By choosing the properties of the LC cell in combination with the appropriate photoconductor thickness and bias potentials, the XLV can be optimized for various diagnostic imaging tasks. Specifically for chest radiography, we identified three potentially practical reflective cell designs by selecting from those commonly used in LC display technology. The relationship between reflectance and x-ray exposure (i.e., the characteristic curve) was determined for all three cells using a theoretical model. The results indicate that the reflective electrically controlled birefringence (r-ECB) cell is the preferred choice for chest radiography, provided that the characteristic curve can be shifted towards lower exposures. The feasibility of the shift of the characteristic curve is shown experimentally. The experimental results thus demonstrate that an XLV based on the r-ECB cell design exhibits a characteristic curve suitable for chest radiography.

[Rare bile duct anatomy variant - Right bile duct intraparenchymal junction into the left bile duct].

PubMed

Gál, Adrián Róbert; Kalmár-Nagy, Károly; Fincsur, András; Horváth, Örs Péter; Vereczkei, András

2018-03-01

The authors present a case of a 67-year-old male patient, who previously had been diagnosed with a malignant liver tumor localized in segment II. He underwent bisegmentectomy (II and III) and partial IV segmentectomy. After the primary surgery jaundice developed, the level of bilirubin increased and after several imaging modalities reoperation was indicated. During the surgery a rare bile duct anatomy variant was found. The right hepatic duct joined the left duct in the parenchyma of the left lobe, and was ligated at the resection. As the liver hilum was not explored, the absence of the right duct was not discovered. Reconstruction of the biliary system was accomplished by a Roux-en-Y loop.

Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System

PubMed Central

Yang, Jong-Ryul; Lee, Woo-Jae; Han, Seong-Tae

2016-01-01

A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS) detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC) offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s. PMID:26950128

Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System.

PubMed

Yang, Jong-Ryul; Lee, Woo-Jae; Han, Seong-Tae

2016-03-02

A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS) detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC) offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s.

3D mouse shape reconstruction based on phase-shifting algorithm for fluorescence molecular tomography imaging system.

PubMed

Zhao, Yue; Zhu, Dianwen; Baikejiang, Reheman; Li, Changqing

2015-11-10

This work introduces a fast, low-cost, robust method based on fringe pattern and phase shifting to obtain three-dimensional (3D) mouse surface geometry for fluorescence molecular tomography (FMT) imaging. We used two pico projector/webcam pairs to project and capture fringe patterns from different views. We first calibrated the pico projectors and the webcams to obtain their system parameters. Each pico projector/webcam pair had its own coordinate system. We used a cylindrical calibration bar to calculate the transformation matrix between these two coordinate systems. After that, the pico projectors projected nine fringe patterns with a phase-shifting step of 2π/9 onto the surface of a mouse-shaped phantom. The deformed fringe patterns were captured by the corresponding webcam respectively, and then were used to construct two phase maps, which were further converted to two 3D surfaces composed of scattered points. The two 3D point clouds were further merged into one with the transformation matrix. The surface extraction process took less than 30 seconds. Finally, we applied the Digiwarp method to warp a standard Digimouse into the measured surface. The proposed method can reconstruct the surface of a mouse-sized object with an accuracy of 0.5 mm, which we believe is sufficient to obtain a finite element mesh for FMT imaging. We performed an FMT experiment using a mouse-shaped phantom with one embedded fluorescence capillary target. With the warped finite element mesh, we successfully reconstructed the target, which validated our surface extraction approach.

Improving the Performance of the Prony Method Using a Wavelet Domain Filter for MRI Denoising

PubMed Central

Lentini, Marianela; Paluszny, Marco

2014-01-01

The Prony methods are used for exponential fitting. We use a variant of the Prony method for abnormal brain tissue detection in sequences of T 2 weighted magnetic resonance images. Here, MR images are considered to be affected only by Rician noise, and a new wavelet domain bilateral filtering process is implemented to reduce the noise in the images. This filter is a modification of Kazubek's algorithm and we use synthetic images to show the ability of the new procedure to suppress noise and compare its performance with respect to the original filter, using quantitative and qualitative criteria. The tissue classification process is illustrated using a real sequence of T 2 MR images, and the filter is applied to each image before using the variant of the Prony method. PMID:24834108

Improving the performance of the prony method using a wavelet domain filter for MRI denoising.

PubMed

Jaramillo, Rodney; Lentini, Marianela; Paluszny, Marco

2014-01-01

The Prony methods are used for exponential fitting. We use a variant of the Prony method for abnormal brain tissue detection in sequences of T 2 weighted magnetic resonance images. Here, MR images are considered to be affected only by Rician noise, and a new wavelet domain bilateral filtering process is implemented to reduce the noise in the images. This filter is a modification of Kazubek's algorithm and we use synthetic images to show the ability of the new procedure to suppress noise and compare its performance with respect to the original filter, using quantitative and qualitative criteria. The tissue classification process is illustrated using a real sequence of T 2 MR images, and the filter is applied to each image before using the variant of the Prony method.

Estimation of vibration frequency of loudspeaker diaphragm by parallel phase-shifting digital holography

NASA Astrophysics Data System (ADS)

Kakue, T.; Endo, Y.; Shimobaba, T.; Ito, T.

2014-11-01

We report frequency estimation of loudspeaker diaphragm vibrating at high speed by parallel phase-shifting digital holography which is a technique of single-shot phase-shifting interferometry. This technique records multiple phaseshifted holograms required for phase-shifting interferometry by using space-division multiplexing. We constructed a parallel phase-shifting digital holography system consisting of a high-speed polarization-imaging camera. This camera has a micro-polarizer array which selects four linear polarization axes for 2 × 2 pixels. We set a loudspeaker as an object, and recorded vibration of diaphragm of the loudspeaker by the constructed system. By the constructed system, we demonstrated observation of vibration displacement of loudspeaker diaphragm. In this paper, we aim to estimate vibration frequency of the loudspeaker diaphragm by applying the experimental results to frequency analysis. Holograms consisting of 128 × 128 pixels were recorded at a frame rate of 262,500 frames per second by the camera. A sinusoidal wave was input to the loudspeaker via a phone connector. We observed displacement of the loudspeaker diaphragm vibrating by the system. We also succeeded in estimating vibration frequency of the loudspeaker diaphragm by applying frequency analysis to the experimental results.

SU-E-J-16: A Review of the Magnitude of Patient Imaging Shifts in Relation to Departmental Policy Changes

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Connor, M; Sansourekidou, P

2014-06-01

Purpose: To evaluate how changes in imaging policy affect the magnitude of shifts applied to patients. Methods: In June 2012, the department's imaging policy was altered to require that any shifts derived from imaging throughout the course of treatment shall be considered systematic only after they were validated with two data points that are consistent in the same direction. Multiple additions and clarifications to the imaging policy were implemented throughout the course of the data collection, but they were mostly of administrative nature. Entered shifts were documented in MOSAIQ (Elekta AB) through the localization offset. The MOSAIQ database was queriedmore » to identify a possible trend. A total of 25,670 entries were analyzed, including four linear accelerators with a combination of MV planar, kV planar and kV three dimensional imaging. The monthly average of the magnitude of the vector was used. Plan relative offsets were excluded. During the evaluated period of time, one of the satellite facilities acquired and implemented Vision RT (AlignRT Inc). Results: After the new policy was implemented the shifts variance and standard deviation decreased. The decrease is linear with time elapsed. Vision RT implementation at one satellite facility reduced the number of overall shifts, specifically for breast patients. Conclusion: Changes in imaging policy have a significant effect on the magnitude of shifts applied to patients. Using two statistical points before applying a shift as persistent decreased the overall magnitude of the shifts applied to patients.« less

Local binary pattern variants-based adaptive texture features analysis for posed and nonposed facial expression recognition

NASA Astrophysics Data System (ADS)

Sultana, Maryam; Bhatti, Naeem; Javed, Sajid; Jung, Soon Ki

2017-09-01

Facial expression recognition (FER) is an important task for various computer vision applications. The task becomes challenging when it requires the detection and encoding of macro- and micropatterns of facial expressions. We present a two-stage texture feature extraction framework based on the local binary pattern (LBP) variants and evaluate its significance in recognizing posed and nonposed facial expressions. We focus on the parametric limitations of the LBP variants and investigate their effects for optimal FER. The size of the local neighborhood is an important parameter of the LBP technique for its extraction in images. To make the LBP adaptive, we exploit the granulometric information of the facial images to find the local neighborhood size for the extraction of center-symmetric LBP (CS-LBP) features. Our two-stage texture representations consist of an LBP variant and the adaptive CS-LBP features. Among the presented two-stage texture feature extractions, the binarized statistical image features and adaptive CS-LBP features were found showing high FER rates. Evaluation of the adaptive texture features shows competitive and higher performance than the nonadaptive features and other state-of-the-art approaches, respectively.

Phase-sensitive two-dimensional neutron shearing interferometer and Hartmann sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, Kevin

2015-12-08

A neutron imaging system detects both the phase shift and absorption of neutrons passing through an object. The neutron imaging system is based on either of two different neutron wavefront sensor techniques: 2-D shearing interferometry and Hartmann wavefront sensing. Both approaches measure an entire two-dimensional neutron complex field, including its amplitude and phase. Each measures the full-field, two-dimensional phase gradients and, concomitantly, the two-dimensional amplitude mapping, requiring only a single measurement.

A cross-sectional evaluation of meditation experience on electroencephalography data by artificial neural network and support vector machine classifiers

PubMed Central

Lee, Yu-Hao; Hsieh, Ya-Ju; Shiah, Yung-Jong; Lin, Yu-Huei; Chen, Chiao-Yun; Tyan, Yu-Chang; GengQiu, JiaCheng; Hsu, Chung-Yao; Chen, Sharon Chia-Ju

2017-01-01

Abstract To quantitate the meditation experience is a subjective and complex issue because it is confounded by many factors such as emotional state, method of meditation, and personal physical condition. In this study, we propose a strategy with a cross-sectional analysis to evaluate the meditation experience with 2 artificial intelligence techniques: artificial neural network and support vector machine. Within this analysis system, 3 features of the electroencephalography alpha spectrum and variant normalizing scaling are manipulated as the evaluating variables for the detection of accuracy. Thereafter, by modulating the sliding window (the period of the analyzed data) and shifting interval of the window (the time interval to shift the analyzed data), the effect of immediate analysis for the 2 methods is compared. This analysis system is performed on 3 meditation groups, categorizing their meditation experiences in 10-year intervals from novice to junior and to senior. After an exhausted calculation and cross-validation across all variables, the high accuracy rate >98% is achievable under the criterion of 0.5-minute sliding window and 2 seconds shifting interval for both methods. In a word, the minimum analyzable data length is 0.5 minute and the minimum recognizable temporal resolution is 2 seconds in the decision of meditative classification. Our proposed classifier of the meditation experience promotes a rapid evaluation system to distinguish meditation experience and a beneficial utilization of artificial techniques for the big-data analysis. PMID:28422856

A cross-sectional evaluation of meditation experience on electroencephalography data by artificial neural network and support vector machine classifiers.

PubMed

Lee, Yu-Hao; Hsieh, Ya-Ju; Shiah, Yung-Jong; Lin, Yu-Huei; Chen, Chiao-Yun; Tyan, Yu-Chang; GengQiu, JiaCheng; Hsu, Chung-Yao; Chen, Sharon Chia-Ju

2017-04-01

To quantitate the meditation experience is a subjective and complex issue because it is confounded by many factors such as emotional state, method of meditation, and personal physical condition. In this study, we propose a strategy with a cross-sectional analysis to evaluate the meditation experience with 2 artificial intelligence techniques: artificial neural network and support vector machine. Within this analysis system, 3 features of the electroencephalography alpha spectrum and variant normalizing scaling are manipulated as the evaluating variables for the detection of accuracy. Thereafter, by modulating the sliding window (the period of the analyzed data) and shifting interval of the window (the time interval to shift the analyzed data), the effect of immediate analysis for the 2 methods is compared. This analysis system is performed on 3 meditation groups, categorizing their meditation experiences in 10-year intervals from novice to junior and to senior. After an exhausted calculation and cross-validation across all variables, the high accuracy rate >98% is achievable under the criterion of 0.5-minute sliding window and 2 seconds shifting interval for both methods. In a word, the minimum analyzable data length is 0.5 minute and the minimum recognizable temporal resolution is 2 seconds in the decision of meditative classification. Our proposed classifier of the meditation experience promotes a rapid evaluation system to distinguish meditation experience and a beneficial utilization of artificial techniques for the big-data analysis.

Fluorescence molecular imaging system with a novel mouse surface extraction method and a rotary scanning scheme

NASA Astrophysics Data System (ADS)

Zhao, Yue; Zhu, Dianwen; Baikejiang, Reheman; Li, Changqing

2015-03-01

We have developed a new fluorescence molecular tomography (FMT) imaging system, in which we utilized a phase shifting method to extract the mouse surface geometry optically and a rotary laser scanning approach to excite fluorescence molecules and acquire fluorescent measurements on the whole mouse body. Nine fringe patterns with a phase shifting of 2π/9 are projected onto the mouse surface by a projector. The fringe patterns are captured using a webcam to calculate a phase map that is converted to the geometry of the mouse surface with our algorithms. We used a DigiWarp approach to warp a finite element mesh of a standard digital mouse to the measured mouse surface thus the tedious and time-consuming procedure from a point cloud to mesh is avoided. Experimental results indicated that the proposed method is accurate with errors less than 0.5 mm. In the FMT imaging system, the mouse is placed inside a conical mirror and scanned with a line pattern laser that is mounted on a rotation stage. After being reflected by the conical mirror, the emitted fluorescence photons travel through central hole of the rotation stage and the band pass filters in a motorized filter wheel, and are collected by a CCD camera. Phantom experimental results of the proposed new FMT imaging system can reconstruct the target accurately.

[The role of sustained attention in shift-contingent change blindness].

PubMed

Nakashima, Ryoichi; Yokosawa, Kazuhiko

2015-02-01

Previous studies of change blindness have examined the effect of temporal factors (e.g., blank duration) on attention in change detection. This study examined the effect of spatial factors (i.e., whether the locations of original and changed objects are the same or different) on attention in change detection, using a shift-contingent change blindness task. We used a flicker paradigm in which the location of a to-be-judged target image was manipulated (shift, no-shift). In shift conditions, the image of an array of objects was spatially shifted so that all objects appeared in new locations; in no-shift conditions, all object images of an array appeared at the same location. The presence of visual stimuli (dots) in the blank display between the two images was.manipulated (dot, no-dot) under the assumption that abrupt onsets of these stimuli would capture attention. Results indicated that change detection performance was improved by exogenous attentional capture in the shift condition. Thus, we suggest that attention can play an important role in change detection during shift-contingent change blindness.

SU-F-J-125: Effects of Couch Position Variability On Dosimetric Accuracy with An MRI-Guided Co-60 Radiation Therapy Machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, P; Thomas, D; Agazaryan, N

2016-06-15

Purpose: Magnetic resonance imaging (MRI) guidance in radiation therapy brings real-time imaging and adaptive planning into the treatment vault where it can account for interfraction and intrafraction movement of soft tissue. The only commercially-available MRI-guided radiation therapy device is a three-head 60Co and MRI system with an integrated treatment planning system (TPS). An up to 20% attenuation of the beam by the couch is well modeled in the TPS. However, variations in the patient’s day-to-day position introduce discrepancies in the actual couch position relative its location as modeled in the treatment plan. For this reason, our institution avoids plans withmore » beams that pass through or near the couch edges. This study looks at plans without restriction on beam angles and investigates the effects of couch shift by simulating shifts of the couch relative to the patient, in order to determine whether couch edge avoidance restrictions can be lifted. Methods: A total of 27 plans from 23 patients were investigated. Couch shifts of 1 and 2 cm were introduced in combinations of lateral and vertical direction to simulate variations in patient positioning on the couch giving 16 shifted plans per reference plan. The shift values of 1 and 2 cm were based on shifts recorded in 320 treatment fractions. Results: Measured couch attenuation versus TPS modeled agreed within 2.1%. Planning Target Volume (PTV) D95 changed less than 1% for 1 and 2 cm couch shifts in only the x-direction and less than 3% for all directions. Conclusion: The dosimetry of all plans with shifts up to ±2 cm was within reasonable clinical tolerances. Robustness of a plan to couch shifts can be tested in the TPS. Inclusion of beams traversing the couch edges should be considered if an improvement in plan quality or delivery time can be achieved.« less

Entropy-guided switching trimmed mean deviation-boosted anisotropic diffusion filter

NASA Astrophysics Data System (ADS)

Nnolim, Uche A.

2016-07-01

An effective anisotropic diffusion (AD) mean filter variant is proposed for filtering of salt-and-pepper impulse noise. The implemented filter is robust to impulse noise ranging from low to high density levels. The algorithm involves a switching scheme in addition to utilizing the unsymmetric trimmed mean/median deviation to filter image noise while greatly preserving image edges, regardless of impulse noise density (ND). It operates with threshold parameters selected manually or adaptively estimated from the image statistics. It is further combined with the partial differential equations (PDE)-based AD for edge preservation at high NDs to enhance the properties of the trimmed mean filter. Based on experimental results, the proposed filter easily and consistently outperforms the median filter and its other variants ranging from simple to complex filter structures, especially the known PDE-based variants. In addition, the switching scheme and threshold calculation enables the filter to avoid smoothing an uncorrupted image, and filtering is activated only when impulse noise is present. Ultimately, the particular properties of the filter make its combination with the AD algorithm a unique and powerful edge-preservation smoothing filter at high-impulse NDs.

Molecular and clinical characterization of a series of patients with childhood-onset lysosomal acid lipase deficiency. Retrospective investigations, follow-up and detection of two novel LIPA pathogenic variants.

PubMed

Pisciotta, Livia; Tozzi, Giulia; Travaglini, Lorena; Taurisano, Roberta; Lucchi, Tiziano; Indolfi, Giuseppe; Papadia, Francesco; Di Rocco, Maja; D'Antiga, Lorenzo; Crock, Patricia; Vora, Komal; Nightingale, Scott; Michelakakis, Helen; Garoufi, Anastasia; Lykopoulou, Lilia; Bertolini, Stefano; Calandra, Sebastiano

2017-10-01

Childhood/Adult-onset Lysosomal Acid Lipase Deficiency (LAL-D) is a recessive disorder due to loss of function variants of LAL, the enzyme which hydrolyses cholesteryl esters, derived from internalized apoB containing lipoproteins. The disease is characterized by multi-organ involvement including the liver, spleen, intestine and cardiovascular system. The aim of this study was the clinical and molecular characterization of 14 (13 unrelated) previously unreported patients with childhood-onset LAL-D. Data collected included clinical and laboratory investigations, liver imaging, liver biopsy and LIPA gene analysis. The response to lipid-lowering medications, liver transplantation and enzyme replacement therapy (ERT) was reported for some patients. LAL-D was suspected at 4.4 ± 3.3 years of age for the presence of hepatomegaly, elevated serum transaminases and hypercholesterolemia, and was confirmed by liver biopsy/imaging and LAL assay. The follow up period ranged from 3 to 40 years (mean 7.8 ± 4.0 years in 13 cases). Patients treated with statins with or without ezetimibe showed 28% reduction of plasma LDL-cholesterol without a tangible effect on liver enzymes; some patients receiving ERT showed normalized lipoprotein profile and transaminase levels. The common c.894G > A variant was observed in homozygosity or compound heterozygosity in 10 patients. We found seven previously reported variants: p.(Trp140*), p.(Arg218*), p.(Gly266*), p.(Thr288Ile), p.(Leu294Ser), p.(His295Tyr) and p.(Gly342Arg) and two novel variants: p.(Asp345Asn), affecting the LAL catalytic triad, and c.229+3A > C, affecting splicing. Homozygosity for p.(Thr288Ile) or c.229+3A > C was associated with a severe phenotype. This study provides additional data on the features of childhood-onset LAL-D and describes two novel pathogenic variants of the LIPA gene. Copyright © 2017. Published by Elsevier B.V.

Dual Channel S-Band Frequency Modulated Continuous Wave Through-Wall Radar Imaging

PubMed Central

Oh, Daegun; Kim, Sunwoo; Chong, Jong-Wha

2018-01-01

This article deals with the development of a dual channel S-Band frequency-modulated continuous wave (FMCW) system for a through-the-wall imaging (TWRI) system. Most existing TWRI systems using FMCW were developed for synthetic aperture radar (SAR) which has many drawbacks such as the need for several antenna elements and movement of the system. Our implemented TWRI system comprises a transmitting antenna and two receiving antennas, resulting in a significant reduction of the number of antenna elements. Moreover, a proposed algorithm for range-angle-Doppler 3D estimation based on a 3D shift invariant structure is utilized in our implemented dual channel S-band FMCW TWRI system. Indoor and outdoor experiments were conducted to image the scene beyond a wall for water targets and person targets, respectively. The experimental results demonstrate that high-quality imaging can be achieved under both experimental scenarios. PMID:29361777

The AAPM/RSNA physics tutorial for residents: digital fluoroscopy.

PubMed

Pooley, R A; McKinney, J M; Miller, D A

2001-01-01

A digital fluoroscopy system is most commonly configured as a conventional fluoroscopy system (tube, table, image intensifier, video system) in which the analog video signal is converted to and stored as digital data. Other methods of acquiring the digital data (eg, digital or charge-coupled device video and flat-panel detectors) will become more prevalent in the future. Fundamental concepts related to digital imaging in general include binary numbers, pixels, and gray levels. Digital image data allow the convenient use of several image processing techniques including last image hold, gray-scale processing, temporal frame averaging, and edge enhancement. Real-time subtraction of digital fluoroscopic images after injection of contrast material has led to widespread use of digital subtraction angiography (DSA). Additional image processing techniques used with DSA include road mapping, image fade, mask pixel shift, frame summation, and vessel size measurement. Peripheral angiography performed with an automatic moving table allows imaging of the peripheral vasculature with a single contrast material injection.

Distinct [18F]THK5351 binding patterns in primary progressive aphasia variants.

PubMed

Schaeverbeke, Jolien; Evenepoel, Charlotte; Declercq, Lieven; Gabel, Silvy; Meersmans, Karen; Bruffaerts, Rose; Adamczuk, Kate; Dries, Eva; Van Bouwel, Karen; Sieben, Anne; Pijnenburg, Yolande; Peeters, Ronald; Bormans, Guy; Van Laere, Koen; Koole, Michel; Dupont, Patrick; Vandenberghe, Rik

2018-06-26

To assess the binding of the PET tracer [ 18 F]THK5351 in patients with different primary progressive aphasia (PPA) variants and its correlation with clinical deficits. The majority of patients with nonfluent variant (NFV) and logopenic variant (LV) PPA have underlying tauopathy of the frontotemporal lobar or Alzheimer disease type, respectively, while patients with the semantic variant (SV) have predominantly transactive response DNA binding protein 43-kDa pathology. The study included 20 PPA patients consecutively recruited through a memory clinic (12 NFV, 5 SV, 3 LV), and 20 healthy controls. All participants received an extensive neurolinguistic assessment, magnetic resonance imaging and amyloid biomarker tests. [ 18 F]THK5351 binding patterns were assessed on standardized uptake value ratio (SUVR) images with the cerebellar grey matter as the reference using statistical parametric mapping. Whole-brain voxel-wise regression analysis was performed to evaluate the association between [ 18 F]THK5351 SUVR images and neurolinguistic scores. Analyses were performed with and without partial volume correction. Patients with NFV showed increased binding in the supplementary motor area, left premotor cortex, thalamus, basal ganglia and midbrain compared with controls and patients with SV. Patients with SV had increased binding in the temporal lobes bilaterally and in the right ventromedial frontal cortex compared with controls and patients with NFV. The whole-brain voxel-wise regression analysis revealed a correlation between agrammatism and motor speech impairment, and [ 18 F]THK5351 binding in the left supplementary motor area and left postcentral gyrus. Analysis of [ 18 F]THK5351 scans without partial volume correction revealed similar results. [ 18 F]THK5351 imaging shows a topography closely matching the anatomical distribution of predicted underlying pathology characteristic of NFV and SV PPA. [ 18 F]THK5351 binding correlates with the severity of clinical impairment.

Coronagraphic Notch Filter for Raman Spectroscopy

NASA Technical Reports Server (NTRS)

Cohen, David; Stirbl, Robert

2004-01-01

A modified coronagraph has been proposed as a prototype of improved notch filters in Raman spectrometers. Coronagraphic notch filters could offer alternatives to both (1) the large and expensive double or triple monochromators in older Raman spectrometers and (2) holographic notch filters, which are less expensive but are subject to environmental degradation as well as to limitations of geometry and spectral range. Measurement of a Raman spectrum is an exercise in measuring and resolving faint spectral lines close to a bright peak: In Raman spectroscopy, a monochromatic beam of light (the pump beam) excites a sample of material that one seeks to analyze. The pump beam generates a small flux of scattered light at wavelengths slightly greater than that of the pump beam. The shift in wavelength of the scattered light from the pump wavelength is known in the art as the Stokes shift. Typically, the flux of scattered light is of the order of 10 7 that of the pump beam and the Stokes shift lies in the wave-number range of 100 to 3,000 cm 1. A notch filter can be used to suppress the pump-beam spectral peak while passing the nearby faint Raman spectral lines. The basic principles of design and operation of a coronagraph offer an opportunity for engineering the spectral transmittance of the optics in a Raman spectrometer. A classical coronagraph may be understood as two imaging systems placed end to end, such that the first system forms an intermediate real image of a nominally infinitely distant object and the second system forms a final real image of the intermediate real image. If the light incident on the first telescope is collimated, then the intermediate image is a point-spread function (PSF). If an appropriately tailored occulting spot (e.g., a Gaussian-apodized spot with maximum absorption on axis) is placed on the intermediate image plane, then the instrument inhibits transmission of light from an on-axis source. However, the PSFs of off-axis light sources are formed off axis - that is, away from the occulting spot - so that they become refocused onto the final image plane.

Bio-image warehouse system: concept and implementation of a diagnosis-based data warehouse for advanced imaging modalities in neuroradiology.

PubMed

Minati, L; Ghielmetti, F; Ciobanu, V; D'Incerti, L; Maccagnano, C; Bizzi, A; Bruzzone, M G

2007-03-01

Advanced neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), chemical shift spectroscopy imaging (CSI), diffusion tensor imaging (DTI), and perfusion-weighted imaging (PWI) create novel challenges in terms of data storage and management: huge amounts of raw data are generated, the results of analysis may depend on the software and settings that have been used, and most often intermediate files are inherently not compliant with the current DICOM (digital imaging and communication in medicine) standard, as they contain multidimensional complex and tensor arrays and various other types of data structures. A software architecture, referred to as Bio-Image Warehouse System (BIWS), which can be used alongside a radiology information system/picture archiving and communication system (RIS/PACS) system to store neuroimaging data for research purposes, is presented. The system architecture is conceived with the purpose of enabling to query by diagnosis according to a predefined two-layered classification taxonomy. The operational impact of the system and the time needed to get acquainted with the web-based interface and with the taxonomy are found to be limited. The development of modules enabling automated creation of statistical templates is proposed.

Identification of rare X-linked neuroligin variants by massively parallel sequencing in males with autism spectrum disorder.

PubMed

Steinberg, Karyn Meltz; Ramachandran, Dhanya; Patel, Viren C; Shetty, Amol C; Cutler, David J; Zwick, Michael E

2012-09-28

Autism spectrum disorder (ASD) is highly heritable, but the genetic risk factors for it remain largely unknown. Although structural variants with large effect sizes may explain up to 15% ASD, genome-wide association studies have failed to uncover common single nucleotide variants with large effects on phenotype. The focus within ASD genetics is now shifting to the examination of rare sequence variants of modest effect, which is most often achieved via exome selection and sequencing. This strategy has indeed identified some rare candidate variants; however, the approach does not capture the full spectrum of genetic variation that might contribute to the phenotype. We surveyed two loci with known rare variants that contribute to ASD, the X-linked neuroligin genes by performing massively parallel Illumina sequencing of the coding and noncoding regions from these genes in males from families with multiplex autism. We annotated all variant sites and functionally tested a subset to identify other rare mutations contributing to ASD susceptibility. We found seven rare variants at evolutionary conserved sites in our study population. Functional analyses of the three 3' UTR variants did not show statistically significant effects on the expression of NLGN3 and NLGN4X. In addition, we identified two NLGN3 intronic variants located within conserved transcription factor binding sites that could potentially affect gene regulation. These data demonstrate the power of massively parallel, targeted sequencing studies of affected individuals for identifying rare, potentially disease-contributing variation. However, they also point out the challenges and limitations of current methods of direct functional testing of rare variants and the difficulties of identifying alleles with modest effects.

Identification of rare X-linked neuroligin variants by massively parallel sequencing in males with autism spectrum disorder

PubMed Central

2012-01-01

Background Autism spectrum disorder (ASD) is highly heritable, but the genetic risk factors for it remain largely unknown. Although structural variants with large effect sizes may explain up to 15% ASD, genome-wide association studies have failed to uncover common single nucleotide variants with large effects on phenotype. The focus within ASD genetics is now shifting to the examination of rare sequence variants of modest effect, which is most often achieved via exome selection and sequencing. This strategy has indeed identified some rare candidate variants; however, the approach does not capture the full spectrum of genetic variation that might contribute to the phenotype. Methods We surveyed two loci with known rare variants that contribute to ASD, the X-linked neuroligin genes by performing massively parallel Illumina sequencing of the coding and noncoding regions from these genes in males from families with multiplex autism. We annotated all variant sites and functionally tested a subset to identify other rare mutations contributing to ASD susceptibility. Results We found seven rare variants at evolutionary conserved sites in our study population. Functional analyses of the three 3’ UTR variants did not show statistically significant effects on the expression of NLGN3 and NLGN4X. In addition, we identified two NLGN3 intronic variants located within conserved transcription factor binding sites that could potentially affect gene regulation. Conclusions These data demonstrate the power of massively parallel, targeted sequencing studies of affected individuals for identifying rare, potentially disease-contributing variation. However, they also point out the challenges and limitations of current methods of direct functional testing of rare variants and the difficulties of identifying alleles with modest effects. PMID:23020841

Multiparametric Flow Cytometry Using Near-Infrared Fluorescent Proteins Engineered from Bacterial Phytochromes

PubMed Central

Telford, William G.; Shcherbakova, Daria M.; Buschke, David; Hawley, Teresa S.; Verkhusha, Vladislav V.

2015-01-01

Engineering of fluorescent proteins (FPs) has followed a trend of achieving longer fluorescence wavelengths, with the ultimate goal of producing proteins with both excitation and emission in the near-infrared (NIR) region of the spectrum. Flow cytometers are now almost universally equipped with red lasers, and can now be equipped with NIR lasers as well. Most red-shifted FPs of the GFP-like family are maximally excited by orange lasers (590 to 610 nm) not commonly found on cytometers. This has changed with the development of the iRFP series of NIR FPs from the protein family of bacterial phytochromes. The shortest wavelength variants of this series, iRFP670 and iRFP682 showed maximal excitation with visible red lasers. The longer wavelength variants iRFP702, iRFP713 and iRFP720 could be optimally excited by NIR lasers ranging from 685 to 730 nm. Pairs of iRFPs could be detected simultaneously by using red and NIR lasers. Moreover, a novel spectral cytometry technique, which relies on spectral deconvolution rather than optical filters, allowed spectra of all five iRFPs to be analyzed simultaneously with no spectral overlap. Together, the combination of iRFPs with the advanced flow cytometry will allow to first image tissues expressing iRFPs deep in live animals and then quantify individual cell intensities and sort out the distinct primary cell subpopulations ex vivo. PMID:25811854

Multiparametric flow cytometry using near-infrared fluorescent proteins engineered from bacterial phytochromes.

PubMed

Telford, William G; Shcherbakova, Daria M; Buschke, David; Hawley, Teresa S; Verkhusha, Vladislav V

2015-01-01

Engineering of fluorescent proteins (FPs) has followed a trend of achieving longer fluorescence wavelengths, with the ultimate goal of producing proteins with both excitation and emission in the near-infrared (NIR) region of the spectrum. Flow cytometers are now almost universally equipped with red lasers, and can now be equipped with NIR lasers as well. Most red-shifted FPs of the GFP-like family are maximally excited by orange lasers (590 to 610 nm) not commonly found on cytometers. This has changed with the development of the iRFP series of NIR FPs from the protein family of bacterial phytochromes. The shortest wavelength variants of this series, iRFP670 and iRFP682 showed maximal excitation with visible red lasers. The longer wavelength variants iRFP702, iRFP713 and iRFP720 could be optimally excited by NIR lasers ranging from 685 to 730 nm. Pairs of iRFPs could be detected simultaneously by using red and NIR lasers. Moreover, a novel spectral cytometry technique, which relies on spectral deconvolution rather than optical filters, allowed spectra of all five iRFPs to be analyzed simultaneously with no spectral overlap. Together, the combination of iRFPs with the advanced flow cytometry will allow to first image tissues expressing iRFPs deep in live animals and then quantify individual cell intensities and sort out the distinct primary cell subpopulations ex vivo.

Identification of missing variants by combining multiple analytic pipelines.

PubMed

Ren, Yingxue; Reddy, Joseph S; Pottier, Cyril; Sarangi, Vivekananda; Tian, Shulan; Sinnwell, Jason P; McDonnell, Shannon K; Biernacka, Joanna M; Carrasquillo, Minerva M; Ross, Owen A; Ertekin-Taner, Nilüfer; Rademakers, Rosa; Hudson, Matthew; Mainzer, Liudmila Sergeevna; Asmann, Yan W

2018-04-16

After decades of identifying risk factors using array-based genome-wide association studies (GWAS), genetic research of complex diseases has shifted to sequencing-based rare variants discovery. This requires large sample sizes for statistical power and has brought up questions about whether the current variant calling practices are adequate for large cohorts. It is well-known that there are discrepancies between variants called by different pipelines, and that using a single pipeline always misses true variants exclusively identifiable by other pipelines. Nonetheless, it is common practice today to call variants by one pipeline due to computational cost and assume that false negative calls are a small percent of total. We analyzed 10,000 exomes from the Alzheimer's Disease Sequencing Project (ADSP) using multiple analytic pipelines consisting of different read aligners and variant calling strategies. We compared variants identified by using two aligners in 50,100, 200, 500, 1000, and 1952 samples; and compared variants identified by adding single-sample genotyping to the default multi-sample joint genotyping in 50,100, 500, 2000, 5000 and 10,000 samples. We found that using a single pipeline missed increasing numbers of high-quality variants correlated with sample sizes. By combining two read aligners and two variant calling strategies, we rescued 30% of pass-QC variants at sample size of 2000, and 56% at 10,000 samples. The rescued variants had higher proportions of low frequency (minor allele frequency [MAF] 1-5%) and rare (MAF < 1%) variants, which are the very type of variants of interest. In 660 Alzheimer's disease cases with earlier onset ages of ≤65, 4 out of 13 (31%) previously-published rare pathogenic and protective mutations in APP, PSEN1, and PSEN2 genes were undetected by the default one-pipeline approach but recovered by the multi-pipeline approach. Identification of the complete variant set from sequencing data is the prerequisite of genetic association analyses. The current analytic practice of calling genetic variants from sequencing data using a single bioinformatics pipeline is no longer adequate with the increasingly large projects. The number and percentage of quality variants that passed quality filters but are missed by the one-pipeline approach rapidly increased with sample size.

Use of astronomy filters in fluorescence microscopy.

PubMed

Piper, Jörg

2012-02-01

Monochrome astronomy filters are well suited for use as excitation or suppression filters in fluorescence microscopy. Because of their particular optical design, such filters can be combined with standard halogen light sources for excitation in many fluorescent probes. In this "low energy excitation," photobleaching (fading) or other irritations of native specimens are avoided. Photomicrographs can be taken from living motile fluorescent specimens also with a flash so that fluorescence images can be created free from indistinctness caused by movement. Special filter cubes or dichroic mirrors are not needed for our method. By use of suitable astronomy filters, fluorescence microscopy can be carried out with standard laboratory microscopes equipped with condensers for bright-field (BF) and dark-field (DF) illumination in transmitted light. In BF excitation, the background brightness can be modulated in tiny steps up to dark or black. Moreover, standard industry microscopes fitted with a vertical illuminator for examinations of opaque probes in DF or BF illumination based on incident light (wafer inspections, for instance) can also be used for excitation in epi-illumination when adequate astronomy filters are inserted as excitatory and suppression filters in the illuminating and imaging light path. In all variants, transmission bands can be modulated by transmission shift.

Design of polarization imaging system based on CIS and FPGA

NASA Astrophysics Data System (ADS)

Zeng, Yan-an; Liu, Li-gang; Yang, Kun-tao; Chang, Da-ding

2008-02-01

As polarization is an important characteristic of light, polarization image detecting is a new image detecting technology of combining polarimetric and image processing technology. Contrasting traditional image detecting in ray radiation, polarization image detecting could acquire a lot of very important information which traditional image detecting couldn't. Polarization image detecting will be widely used in civilian field and military field. As polarization image detecting could resolve some problem which couldn't be resolved by traditional image detecting, it has been researched widely around the world. The paper introduces polarization image detecting in physical theory at first, then especially introduces image collecting and polarization image process based on CIS (CMOS image sensor) and FPGA. There are two parts including hardware and software for polarization imaging system. The part of hardware include drive module of CMOS image sensor, VGA display module, SRAM access module and the real-time image data collecting system based on FPGA. The circuit diagram and PCB was designed. Stokes vector and polarization angle computing method are analyzed in the part of software. The float multiply of Stokes vector is optimized into just shift and addition operation. The result of the experiment shows that real time image collecting system could collect and display image data from CMOS image sensor in real-time.

Selective Survival of Nonpigmented Mutants in Pasteurella Pestis Cultures

DTIC Science & Technology

Differential death rates that occur under certain conditions in cultures of Pasteurella pestis result in dramatic population shifts. Comparable...growth and death rates were observed for pigmented inocula and their nonpigmented variants in a casein digest (NZ-Amine, Sheffield, Type A) medium

Genetic literacy series: Primer part 2-Paradigm shifts in epilepsy genetics.

PubMed

Helbig, Ingo; Heinzen, Erin L; Mefford, Heather C

2018-05-09

This is the second of a 2-part primer on the genetics of the epilepsies within the Genetic Literacy Series of the Genetics Commission of the International League Against Epilepsy. In Part 1, we covered types of genetic variation, inheritance patterns, and their relationship to disease. In Part 2, we apply these basic principles to the case of a young boy with epileptic encephalopathy and ask 3 important questions: (1) Is the gene in question an established genetic etiology for epilepsy? (2) Is the variant in this particular gene pathogenic by established variant interpretation criteria? (3) Is the variant considered causative in the clinical context? These questions are considered and then answered for the clinical case in question. Wiley Periodicals, Inc. © 2018 International League Against Epilepsy.

Mid-frequency MTF compensation of optical sparse aperture system.

PubMed

Zhou, Chenghao; Wang, Zhile

2018-03-19

Optical sparse aperture (OSA) can greatly improve the spatial resolution of optical system. However, because of its aperture dispersion and sparse, its mid-frequency modulation transfer function (MTF) are significantly lower than that of a single aperture system. The main focus of this paper is on the mid-frequency MTF compensation of the optical sparse aperture system. Firstly, the principle of the mid-frequency MTF decreasing and missing of optical sparse aperture are analyzed. This paper takes the filling factor as a clue. The method of processing the mid-frequency MTF decreasing with large filling factor and method of compensation mid-frequency MTF with small filling factor are given respectively. For the MTF mid-frequency decreasing, the image spatial-variant restoration method is proposed to restore the mid-frequency information in the image; for the mid-frequency MTF missing, two images obtained by two system respectively are fused to compensate the mid-frequency information in optical sparse aperture image. The feasibility of the two method are analyzed in this paper. The numerical simulation of the system and algorithm of the two cases are presented using Zemax and Matlab. The results demonstrate that by these two methods the mid-frequency MTF of OSA system can be compensated effectively.

Tratamiento formal de imágenes astronómicas con PSF espacialmente variable

NASA Astrophysics Data System (ADS)

Sánchez, B. O.; Domínguez, M. J.; Lares, M.

2017-10-01

We present a python implementation of a method for PSF determination in the context of optimal subtraction of astronomical images. We introduce an expansion of the spatially variant point spread function (PSF) in terms of the Karhunen Loève basis. The advantage of this approach is that the basis is able to naturally adapt to the data, instead of imposing a fixed ad-hoc analytic form. Simulated image reconstruction was analyzed, by using the measured PSF, with good agreement in terms of sky background level between the reconstructed and original images. The technique is simple enough to be implemented on more sophisticated image subtraction methods, since it improves its results without extra computational cost in a spatially variant PSF environment.

Incidence of numerical variants and transitional lumbosacral vertebrae on whole-spine MRI.

PubMed

Tins, Bernhard J; Balain, Birender

2016-04-01

This study sets out to prospectively investigate the incidence of transitional vertebrae and numerical variants of the spine. Over a period of 28 months, MRIs of the whole spine were prospectively evaluated for the presence of transitional lumbosacral vertebrae and numerical variants of the spine. MRI of the whole spine was evaluated in 420 patients, comprising 211 female and 209 male subjects. Two patients had more complex anomalies. Lumbosacral transitional vertebrae were seen in 12 patients: eight sacralised L5 (3 male, 5 female) and four lumbarised S1 (3 male, 1 female). The incidence of transitional vertebrae was approximately 3.3. % (14/418). Thirty-two (7.7 %) of 418 patients had numerical variants of mobile vertebrae of the spine without transitional vertebrae. The number of mobile vertebrae was increased by one in 18 patients (12 male, 6 female), and the number was decreased by one in 14 patients (4 male, 10 female). Numerical variants of the spine are common, and were found to be almost 2.5 times as frequent as transitional lumbosacral vertebrae in the study population. Only whole-spine imaging can identify numerical variants and the anatomical nature of transitional vertebrae. The tendency is toward an increased number of mobile vertebrae in men and a decreased number in women. Main messages • Numerical variants of the spine are more common than transitional vertebrae. • Spinal numerical variants can be reliably identified only with whole-spine imaging. • Increased numbers of vertebrae are more common in men than women. • Transitional lumbosacral vertebrae occurred in about 3.3 % of the study population. • The incidence of numerical variants of the spine was about 7.7 %.

An Ultraconserved Brain-specific Enhancer within ADGRL3 (LPHN3) Underpins ADHD Susceptibility

PubMed Central

Martinez, Ariel F.; Abe, Yu; Hong, Sungkook; Molyneux, Kevin; Yarnell, David; Löhr, Heiko; Driever, Wolfgang; Acosta, Maria T.; Arcos-Burgos, Mauricio; Muenke, Maximilian

2016-01-01

BACKGROUND Genetic factors predispose to attention deficit/hyperactivity disorder (ADHD). Previous studies have reported linkage and association to ADHD of gene variants within ADGRL3. In this study, we functionally analyzed non-coding variants in this gene as likely pathological contributors. METHODS In silico, in vitro and in vivo approaches were used to identify and characterize evolutionary conserved elements within the ADGRL3 linkage region (~207 Kb). Family-based genetic analyses on 838 individuals (372 affected and 466 unaffected) identified ADHD-associated SNPs harbored in some of these conserved elements. Luciferase assays and zebrafish GFP transgenesis tested conserved elements for transcriptional enhancer activity. Electromobility shift assays were used to verify transcription factor binding disruption by ADHD risk alleles. RESULTS An ultraconserved element was discovered (ECR47) that functions as a transcriptional enhancer. A three-variant ADHD risk haplotype in ECR47, formed by rs17226398, rs56038622 and rs2271338, reduced enhancer activity by 40% in neuroblastoma and astrocytoma cells (PBonferroni<0.0001). This enhancer also drove GFP expression in the zebrafish brain in a tissue-specific manner, sharing aspects of endogenous ADGRL3 expression. The rs2271338 risk allele disrupts binding of YY1, an important factor in the development and function of the central nervous system. Expression quantitative trait loci analysis of post-mortem human brain tissues revealed an association between rs2271338 and reduced ADGRL3 expression in the thalamus. CONCLUSIONS These results uncover the first functional evidence of common non-coding variants with potential implications for the pathology of ADHD. PMID:27692237

When Cathy Was a Little Girl: The Healing "Praxis" of Tarot Images

ERIC Educational Resources Information Center

Semetsky, Inna

2010-01-01

This paper is a sequel to an earlier article that presented an argument for Tarot symbolic system functioning as a "techne" that can serve as a valuable educational aid. The present paper shifts the focus from "techne" to "praxis" as a practical art of interpreting images and creating imaginative narratives in the context of counselling and…

Telecentric 3D profilometry based on phase-shifting fringe projection.

PubMed

Li, Dong; Liu, Chunyang; Tian, Jindong

2014-12-29

Three dimensional shape measurement in the microscopic range becomes increasingly important with the development of micro manufacturing technology. Microscopic fringe projection techniques offer a fast, robust, and full-field measurement for field sizes from approximately 1 mm² to several cm². However, the depth of field is very small due to the imaging of non-telecentric microscope, which is often not sufficient to measure the complete depth of a 3D-object. And the calibration of phase-to-depth conversion is complicated which need a precision translation stage and a reference plane. In this paper, we propose a novel telecentric phase-shifting projected fringe profilometry for small and thick objects. Telecentric imaging extends the depth of field approximately to millimeter order, which is much larger than that of microscopy. To avoid the complicated phase-to-depth conversion in microscopic fringe projection, we develop a new system calibration method of camera and projector based on telecentric imaging model. Based on these, a 3D reconstruction of telecentric imaging is presented with stereovision aided by fringe phase maps. Experiments demonstrated the feasibility and high measurement accuracy of the proposed system for thick object.

Fast and robust standard-deviation-based method for bulk motion compensation in phase-based functional OCT.

PubMed

Wei, Xiang; Camino, Acner; Pi, Shaohua; Cepurna, William; Huang, David; Morrison, John C; Jia, Yali

2018-05-01

Phase-based optical coherence tomography (OCT), such as OCT angiography (OCTA) and Doppler OCT, is sensitive to the confounding phase shift introduced by subject bulk motion. Traditional bulk motion compensation methods are limited by their accuracy and computing cost-effectiveness. In this Letter, to the best of our knowledge, we present a novel bulk motion compensation method for phase-based functional OCT. Bulk motion associated phase shift can be directly derived by solving its equation using a standard deviation of phase-based OCTA and Doppler OCT flow signals. This method was evaluated on rodent retinal images acquired by a prototype visible light OCT and human retinal images acquired by a commercial system. The image quality and computational speed were significantly improved, compared to two conventional phase compensation methods.

Centromere Binding and Evolution of Chromosomal Partition Systems in the Burkholderiales

PubMed Central

Passot, Fanny M.; Calderon, Virginie; Fichant, Gwennaele; Lane, David

2012-01-01

How split genomes arise and evolve in bacteria is poorly understood. Since each replicon of such genomes encodes a specific partition (Par) system, the evolution of Par systems could shed light on their evolution. The cystic fibrosis pathogen Burkholderia cenocepacia has three chromosomes (c1, c2, and c3) and one plasmid (pBC), whose compatibility depends on strictly specific interactions of the centromere sequences (parS) with their cognate binding proteins (ParB). However, the Par systems of B. cenocepacia c2, c3, and pBC share many features, suggesting that they arose within an extended family. Database searching revealed seven subfamilies of Par systems like those of B. cenocepacia. All are from plasmids and secondary chromosomes of the Burkholderiales, which reinforces the proposal of an extended family. The subfamily of the Par system of B. cenocepacia c3 includes plasmid variants with parS sequences divergent from that of c3. Using electrophoretic mobility shift assay (EMSA), we found that ParB-c3 binds specifically to centromeres of these variants, despite high DNA sequence divergence. We suggest that the Par system of B. cenocepacia c3 has preserved the features of an ancestral system. In contrast, these features have diverged variably in the plasmid descendants. One such descendant is found both in Ralstonia pickettii 12D, on a free plasmid, and in Ralstonia pickettii 12J, on a plasmid integrated into the main chromosome. These observations suggest that we are witnessing a plasmid-chromosome interaction from which a third chromosome will emerge in a two-chromosome species. PMID:22522899

Centromere binding and evolution of chromosomal partition systems in the Burkholderiales.

PubMed

Passot, Fanny M; Calderon, Virginie; Fichant, Gwennaele; Lane, David; Pasta, Franck

2012-07-01

How split genomes arise and evolve in bacteria is poorly understood. Since each replicon of such genomes encodes a specific partition (Par) system, the evolution of Par systems could shed light on their evolution. The cystic fibrosis pathogen Burkholderia cenocepacia has three chromosomes (c1, c2, and c3) and one plasmid (pBC), whose compatibility depends on strictly specific interactions of the centromere sequences (parS) with their cognate binding proteins (ParB). However, the Par systems of B. cenocepacia c2, c3, and pBC share many features, suggesting that they arose within an extended family. Database searching revealed seven subfamilies of Par systems like those of B. cenocepacia. All are from plasmids and secondary chromosomes of the Burkholderiales, which reinforces the proposal of an extended family. The subfamily of the Par system of B. cenocepacia c3 includes plasmid variants with parS sequences divergent from that of c3. Using electrophoretic mobility shift assay (EMSA), we found that ParB-c3 binds specifically to centromeres of these variants, despite high DNA sequence divergence. We suggest that the Par system of B. cenocepacia c3 has preserved the features of an ancestral system. In contrast, these features have diverged variably in the plasmid descendants. One such descendant is found both in Ralstonia pickettii 12D, on a free plasmid, and in Ralstonia pickettii 12J, on a plasmid integrated into the main chromosome. These observations suggest that we are witnessing a plasmid-chromosome interaction from which a third chromosome will emerge in a two-chromosome species.

Non-unity molecular heritability demonstrated by continuous evolution in vitro

NASA Technical Reports Server (NTRS)

Schmitt, T.; Lehman, N.

1999-01-01

INTRODUCTION: When catalytic RNA is evolved in vitro, the molecule's chemical reactivity is usually the desired selection target. Sometimes the phenotype of a particular RNA molecule cannot be unambiguously determined from its genotype, however. This can occur if a nucleotide sequence can adopt multiple folded states, an example of non-unity heritability (i.e. one genotype gives rise to more than one phenotype). In these cases, more rounds of selection are required to achieve a phenotypic shift. We tested the influence of non-unity heritability at the molecular level by selecting for variants of a ligase ribozyme via continuous evolution. RESULTS: During 20 bursts of continuous evolution of a 152-nucleotide ligase ribozyme in which the Mg2+ concentration was periodically lowered, a nine-error variant of the starting 'wild-type' molecule became dominant in the last eight bursts. This variant appears to be more active than the wild type. Kinetic analyses of the mutant suggest that it may not possess a higher first-order catalytic rate constant, however. Examination of the multiple RNA conformations present under the continuous evolution conditions suggests that the mutant is superior to the wild type because it is less likely to misfold into inactive conformers. CONCLUSIONS: The evolution of genotypes that are more likely to exhibit a particular phenotype is an epiphenomenon usually ascribed only to complex living systems. We show that this can occur at the molecular level, demonstrating that in vitro systems may have more life-like characteristics than previously thought, and providing additional support for an RNA world.

Development of Michelson interferometer based spatial phase-shift digital shearography

NASA Astrophysics Data System (ADS)

Xie, Xin

Digital shearography is a non-contact, full field, optical measurement method, which has the capability of directly measuring the gradient of deformation. For high measurement sensitivity, phase evaluation method has to be introduced into digital shearography by phase-shift technique. Catalog by phase-shift method, digital phase-shift shearography can be divided into Temporal Phase-Shift Digital Shearography (TPS-DS) and Spatial Phase-Shift Digital Shearography (SPS-DS). TPS-DS is the most widely used phase-shift shearography system, due to its simple algorithm, easy operation and good phase-map quality. However, the application of TPS-DS is only limited in static/step-by-step loading measurement situation, due to its multi-step shifting process. In order to measure the strain under dynamic/continuous loading situation, a SPS-DS system has to be developed. This dissertation aims to develop a series of Michelson Interferometer based SPS-DS measurement methods to achieve the strain measurement by using only a single pair of speckle pattern images. The Michelson Interferometer based SPS-DS systems utilize special designed optical setup to introduce extra carrier frequency into the laser wavefront. The phase information corresponds to the strain field can be separated on the Fourier domain using a Fourier Transform and can further be evaluated with a Windowed Inverse Fourier Transform. With different optical setups and carrier frequency arrangements, the Michelson Interferometer based SPS-DS method is capable to achieve a variety of measurement tasks using only single pair of speckle pattern images. Catalog by the aimed measurand, these capable measurement tasks can be divided into five categories: 1) measurement of out-of-plane strain field with small shearing amount; 2) measurement of relative out-of-plane deformation field with big shearing amount; 3) simultaneous measurement of relative out-of-plane deformation field and deformation gradient field by using multiple carrier frequencies; 4) simultaneous measurement of two directional strain field using dual measurement channels 5) measurement of pure in-plane strain and pure out-of-plane strain with multiple carrier frequencies. The basic theory, optical path analysis, preliminary studies, results analysis and research plan are shown in detail in this dissertation.

The Relation between Factor Score Estimates, Image Scores, and Principal Component Scores

ERIC Educational Resources Information Center

Velicer, Wayne F.

1976-01-01

Investigates the relation between factor score estimates, principal component scores, and image scores. The three methods compared are maximum likelihood factor analysis, principal component analysis, and a variant of rescaled image analysis. (RC)

Problem of intraoperative anatomical shift in image-guided surgery

NASA Astrophysics Data System (ADS)

Nauta, Haring J.; Bonnen, J. G.

1998-06-01

Experience with image guided, frameless stereotactic neurosurgery shows that intraoperative brain position shifts can be large enough to be problematic, and can occur in different directions at different directions at different stages of an operation. An understanding of the behavior of shifts will allow the surgeon to make the most appropriate use of the image guidance by first minimizing the shift itself, and then anticipating and compensating for any influence the remaining shift will have on the accuracy of the guidance. Three types of shift are described. Type I shift is a local outward bulging that occurs after the skull and dura are opened but before a mass lesion is resected. Type II shift is a local collapse of the brain tissue into the space previously occupied by the tumor. Type III shift is related to loss of cerebrospinal fluid or brain dehydration and is a generalized, more symmetric loss of brain volume. Strategies to minimize these types of shift include appropriate use of medical measures to reduce brain swelling early in the procedure without producing so much brain dehydration that Type II shift is accentuated later in the procedure. Other strategies include mechanical stabilization of brain position with retractors. Anticipating shift, the neurosurgeon should use the guidance as far as possible to map key boundaries early in the procedure before shift becomes more pronounced. Ultimately, however, the correction for the problem of intraoperative brain shift will require the ability to update the imaging data during the surgery.

Exploiting chromatic aberration to spectrally encode depth in reflectance confocal microscopy

NASA Astrophysics Data System (ADS)

Carrasco-Zevallos, Oscar; Shelton, Ryan L.; Olsovsky, Cory; Saldua, Meagan; Applegate, Brian E.; Maitland, Kristen C.

2011-06-01

We present chromatic confocal microscopy as a technique to axially scan the sample by spectrally encoding depth information to avoid mechanical scanning of the lens or sample. We have achieved an 800 μm focal shift over a range of 680-1080 nm using a hyperchromat lens as the imaging lens. A more complex system that incorporates a water immersion objective to improve axial resolution was built and tested. We determined that increasing objective magnification decreases chromatic shift while improving axial resolution. Furthermore, collimating after the hyperchromat at longer wavelengths yields an increase in focal shift.

Restoration of retinal images with space-variant blur.

PubMed

Marrugo, Andrés G; Millán, María S; Sorel, Michal; Sroubek, Filip

2014-01-01

Retinal images are essential clinical resources for the diagnosis of retinopathy and many other ocular diseases. Because of improper acquisition conditions or inherent optical aberrations in the eye, the images are often degraded with blur. In many common cases, the blur varies across the field of view. Most image deblurring algorithms assume a space-invariant blur, which fails in the presence of space-variant (SV) blur. In this work, we propose an innovative strategy for the restoration of retinal images in which we consider the blur to be both unknown and SV. We model the blur by a linear operation interpreted as a convolution with a point-spread function (PSF) that changes with the position in the image. To achieve an artifact-free restoration, we propose a framework for a robust estimation of the SV PSF based on an eye-domain knowledge strategy. The restoration method was tested on artificially and naturally degraded retinal images. The results show an important enhancement, significant enough to leverage the images' clinical use.

Spatial filtering velocimeter for vehicle navigation with extended measurement range

NASA Astrophysics Data System (ADS)

He, Xin; Zhou, Jian; Nie, Xiaoming; Long, Xingwu

2015-05-01

The idea of using spatial filtering velocimeter is proposed to provide accurate velocity information for vehicle autonomous navigation system. The presented spatial filtering velocimeter is based on a CMOS linear image sensor. The limited frame rate restricts high speed measurement of the vehicle. To extend measurement range of the velocimeter, a method of frequency shifting is put forward. Theoretical analysis shows that the frequency of output signal can be reduced and the measurement range can be doubled by this method when the shifting direction is set the same with that of image velocity. The approach of fast Fourier transform (FFT) is employed to obtain the power spectra of the spatially filtered signals. Because of limited frequency resolution of FFT, a frequency spectrum correction algorithm, called energy centrobaric correction, is used to improve the frequency resolution. The correction accuracy energy centrobaric correction is analyzed. Experiments are carried out to measure the moving surface of a conveyor belt. The experimental results show that the maximum measurable velocity is about 800deg/s without frequency shifting, 1600deg/s with frequency shifting, when the frame rate of the image is about 8117 Hz. Therefore, the measurement range is doubled by the method of frequency shifting. Furthermore, experiments were carried out to measure the vehicle velocity simultaneously using both the designed SFV and a laser Doppler velocimeter (LDV). The measurement results of the presented SFV are coincident with that of the LDV, but with bigger fluctuation. Therefore, it has the potential of application to vehicular autonomous navigation.

Functional validation and comparison framework for EIT lung imaging.

PubMed

Grychtol, Bartłomiej; Elke, Gunnar; Meybohm, Patrick; Weiler, Norbert; Frerichs, Inéz; Adler, Andy

2014-01-01

Electrical impedance tomography (EIT) is an emerging clinical tool for monitoring ventilation distribution in mechanically ventilated patients, for which many image reconstruction algorithms have been suggested. We propose an experimental framework to assess such algorithms with respect to their ability to correctly represent well-defined physiological changes. We defined a set of clinically relevant ventilation conditions and induced them experimentally in 8 pigs by controlling three ventilator settings (tidal volume, positive end-expiratory pressure and the fraction of inspired oxygen). In this way, large and discrete shifts in global and regional lung air content were elicited. We use the framework to compare twelve 2D EIT reconstruction algorithms, including backprojection (the original and still most frequently used algorithm), GREIT (a more recent consensus algorithm for lung imaging), truncated singular value decomposition (TSVD), several variants of the one-step Gauss-Newton approach and two iterative algorithms. We consider the effects of using a 3D finite element model, assuming non-uniform background conductivity, noise modeling, reconstructing for electrode movement, total variation (TV) reconstruction, robust error norms, smoothing priors, and using difference vs. normalized difference data. Our results indicate that, while variation in appearance of images reconstructed from the same data is not negligible, clinically relevant parameters do not vary considerably among the advanced algorithms. Among the analysed algorithms, several advanced algorithms perform well, while some others are significantly worse. Given its vintage and ad-hoc formulation backprojection works surprisingly well, supporting the validity of previous studies in lung EIT.

SU-C-207B-07: Deep Convolutional Neural Network Image Matching for Ultrasound Guidance in Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, N; Najafi, M; Hancock, S

Purpose: Robust matching of ultrasound images is a challenging problem as images of the same anatomy often present non-trivial differences. This poses an obstacle for ultrasound guidance in radiotherapy. Thus our objective is to overcome this obstacle by designing and evaluating an image blocks matching framework based on a two channel deep convolutional neural network. Methods: We extend to 3D an algorithmic structure previously introduced for 2D image feature learning [1]. To obtain the similarity between two 3D image blocks A and B, the 3D image blocks are divided into 2D patches Ai and Bi. The similarity is then calculatedmore » as the average similarity score of Ai and Bi. The neural network was then trained with public non-medical image pairs, and subsequently evaluated on ultrasound image blocks for the following scenarios: (S1) same image blocks with/without shifts (A and A-shift-x); (S2) non-related random block pairs; (S3) ground truth registration matched pairs of different ultrasound images with/without shifts (A-i and A-reg-i-shift-x). Results: For S1 the similarity scores of A and A-shift-x were 32.63, 18.38, 12.95, 9.23, 2.15 and 0.43 for x=ranging from 0 mm to 10 mm in 2 mm increments. For S2 the average similarity score for non-related block pairs was −1.15. For S3 the average similarity score of ground truth registration matched blocks A-i and A-reg-i-shift-0 (1≤i≤5) was 12.37. After translating A-reg-i-shift-0 by 0 mm, 2 mm, 4 mm, 6 mm, 8 mm, and 10 mm, the average similarity scores of A-i and A-reg-i-shift-x were 11.04, 8.42, 4.56, 2.27, and 0.29 respectively. Conclusion: The proposed method correctly assigns highest similarity to corresponding 3D ultrasound image blocks despite differences in image content and thus can form the basis for ultrasound image registration and tracking.[1] Zagoruyko, Komodakis, “Learning to compare image patches via convolutional neural networks', IEEE CVPR 2015,pp.4353–4361.« less

ECG-gated imaging of the left atrium and pulmonary veins: Intra-individual comparison of CTA and MRA.

PubMed

Fahlenkamp, U L; Lembcke, A; Roesler, R; Schwenke, C; Huppertz, A; Streitparth, F; Taupitz, M; Hamm, B; Wagner, M

2013-10-01

To compare electrocardiography (ECG)-gated computed tomography angiography (CTA) with ECG-gated magnetic resonance angiography (MRA) for assessment of the left atrium (LA) and pulmonary veins (PVs). Twenty-nine consecutive patients who underwent both cardiac CTA and MRA were evaluated. Contrast-enhanced CTA was performed with prospective ECG-gating using a 320 detector row CT system. Contrast-enhanced MRA was performed with prospective ECG-gating using a 1.5 T MRI system equipped with a 32 channel cardiac coil. MRA was acquired during free-breathing with a navigator-gated inversion-recovery prepared steady-state free precession sequence. Two readers independently assessed the CTA and MRA images for vascular definition of the PVs (from 0, not visualized, to 4, excellent definition) and ostial PV diameters. Variants of LA anatomy were assessed in consensus. CTA was successfully performed in all patients with a mean radiation exposure of 5.1 ± 2.2 mSv. MRA was successfully performed in 27 of 29 patients (93 %). Visual definition of PVs was rated significantly higher on CTA compared to MRA (p < 0.0001; reader 1: excellent/good ratings of CTA versus MRA: 100% versus 86%; reader 2: excellent/good ratings of CTA versus MRA: 99% versus 89%). Assessment of ostial PV diameters showed good correlation between CTA and MRA (reader 1: Pearson r = 0.91; reader 2: Pearson r = 0.82). Moreover, agreement between both imaging methods for evaluation of variants of LA anatomy was high (agreement rate of 95% (95% CI: 92-99%). ECG-gated CTA provides higher image quality compared to ECG-gated MRA. Nevertheless, both CTA and MRA provided similar information of LA anatomy and ostial PV diameters. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Improving response inhibition systems in frontotemporal dementia with citalopram.

PubMed

Hughes, Laura E; Rittman, Timothy; Regenthal, Ralf; Robbins, Trevor W; Rowe, James B

2015-07-01

Disinhibition is a cardinal feature of the behavioural variant of frontotemporal dementia, presenting as impulsive and impetuous behaviours that are often difficult to manage. The options for symptomatic treatments are limited, but a potential target for therapy is the restoration of serotonergic function, which is both deficient in behavioural variant frontotemporal dementia and closely associated with inhibitory control. Based on preclinical studies and psychopharmacological interventions in other disorders, we predicted that inhibition would be associated with the right inferior frontal gyrus and dependent on serotonin. Using magnetoencephalography and electroencephalography of a Go-NoGo paradigm, we investigated the neural basis of behavioural disinhibition in behavioural variant frontotemporal dementia and the effect of selective serotonin reuptake inhibition on the neural systems for response inhibition. In a randomized double-blinded placebo-controlled crossover design study, 12 patients received either a single 30 mg dose of citalopram or placebo. Twenty age-matched healthy controls underwent the same magnetoencephalography/electroencephalography protocol on one session without citalopram, providing normative data for this task. In the control group, successful NoGo trials evoked two established indices of successful response inhibition: the NoGo-N2 and NoGo-P3. Both of these components were significantly attenuated by behavioural variant frontotemporal dementia. Cortical sources associated with successful inhibition in control subjects were identified in the right inferior frontal gyrus and anterior temporal lobe, which have been strongly associated with behavioural inhibition in imaging and lesion studies. These sources were impaired by behavioural variant frontotemporal dementia. Critically, citalopram enhanced the NoGo-P3 signal in patients, relative to placebo treatment, and increased the evoked response in the right inferior frontal gyrus. Voxel-based morphometry confirmed significant atrophy of inferior frontal gyrus, alongside insular, orbitofrontal and temporal cortex in our patient cohort. Together, these data suggest that the dysfunctional prefrontal cortical systems underlying response inhibition deficits in behavioural variant frontotemporal dementia can be partially restored by increasing serotonergic neurotransmission. The results support a translational neuroscience approach to impulsive neurological disorders and indicate the potential for symptomatic treatment of behavioural variant frontotemporal dementia including serotonergic strategies to improve disinhibition.media-1vid110.1093/brain/awv133_video_abstractawv133_video_abstract. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain.

Insight into efficient image registration techniques and the demons algorithm.

PubMed

Vercauteren, Tom; Pennec, Xavier; Malis, Ezio; Perchant, Aymeric; Ayache, Nicholas

2007-01-01

As image registration becomes more and more central to many biomedical imaging applications, the efficiency of the algorithms becomes a key issue. Image registration is classically performed by optimizing a similarity criterion over a given spatial transformation space. Even if this problem is considered as almost solved for linear registration, we show in this paper that some tools that have recently been developed in the field of vision-based robot control can outperform classical solutions. The adequacy of these tools for linear image registration leads us to revisit non-linear registration and allows us to provide interesting theoretical roots to the different variants of Thirion's demons algorithm. This analysis predicts a theoretical advantage to the symmetric forces variant of the demons algorithm. We show that, on controlled experiments, this advantage is confirmed, and yields a faster convergence.

Sensor-based auto-focusing system using multi-scale feature extraction and phase correlation matching.

PubMed

Jang, Jinbeum; Yoo, Yoonjong; Kim, Jongheon; Paik, Joonki

2015-03-10

This paper presents a novel auto-focusing system based on a CMOS sensor containing pixels with different phases. Robust extraction of features in a severely defocused image is the fundamental problem of a phase-difference auto-focusing system. In order to solve this problem, a multi-resolution feature extraction algorithm is proposed. Given the extracted features, the proposed auto-focusing system can provide the ideal focusing position using phase correlation matching. The proposed auto-focusing (AF) algorithm consists of four steps: (i) acquisition of left and right images using AF points in the region-of-interest; (ii) feature extraction in the left image under low illumination and out-of-focus blur; (iii) the generation of two feature images using the phase difference between the left and right images; and (iv) estimation of the phase shifting vector using phase correlation matching. Since the proposed system accurately estimates the phase difference in the out-of-focus blurred image under low illumination, it can provide faster, more robust auto focusing than existing systems.

Sensor-Based Auto-Focusing System Using Multi-Scale Feature Extraction and Phase Correlation Matching

PubMed Central

Jang, Jinbeum; Yoo, Yoonjong; Kim, Jongheon; Paik, Joonki

2015-01-01

This paper presents a novel auto-focusing system based on a CMOS sensor containing pixels with different phases. Robust extraction of features in a severely defocused image is the fundamental problem of a phase-difference auto-focusing system. In order to solve this problem, a multi-resolution feature extraction algorithm is proposed. Given the extracted features, the proposed auto-focusing system can provide the ideal focusing position using phase correlation matching. The proposed auto-focusing (AF) algorithm consists of four steps: (i) acquisition of left and right images using AF points in the region-of-interest; (ii) feature extraction in the left image under low illumination and out-of-focus blur; (iii) the generation of two feature images using the phase difference between the left and right images; and (iv) estimation of the phase shifting vector using phase correlation matching. Since the proposed system accurately estimates the phase difference in the out-of-focus blurred image under low illumination, it can provide faster, more robust auto focusing than existing systems. PMID:25763645

Variability in clinical phenotypes of PRPF8-linked autosomal dominant retinitis pigmentosa correlates with differential PRPF8/SNRNP200 interactions.

PubMed

Escher, Pascal; Passarin, Olga; Munier, Francis L; Tran, Viet H; Vaclavik, Veronika

2018-01-01

To expand the genotype/phenotype correlations in patients with autosomal dominant retinitis pigmentosa (adRP) harboring PRPF8 variants. Two patients, a father and his daughter, harboring a novel p.PRPF8-Glu2331* variant, underwent ophthalmic examination at 3-year-interval, including fundus photography, fundus autofluorescence, optical coherence tomography, and ISCEV standard full field ERGs. All reported disease-causing PRPF8 variants were collected and localized in the PRPF8 and PRPF8/SNRNP200 protein structures. The p.PRPF8-Glu2331* variant results in a truncated PRPF8 protein lacking the last five C-terminal amino acids and caused in the two patients a severe clinical phenotype, with the macula being affected from the second decade on. All but two adRP-linked variants are located in the last exon 43 encoding the C-terminal tail of the C-terminal PRPF8 Jab1 domain. The p.PRPF8-Ser2118Phe and -Asn2280Lys variants encoded by exons 39 and 42, respectively, are located at the basis of the C-terminal tail. Frame-shift mutations and nonconservative amino acid changes in PRPF8 typically cause severe clinical phenotypes. The conservative missense variant p.PRPF8-Arg2310Lys that is not altering the global charge of the C-terminal tail, and variants located at the basis of the C-terminal tail show milder clinical phenotypes, in accordance with functional data on PRPF8/SNRNP200 interactions in yeast.

Shift work-related problems in 16-h night shift nurses (1): Development of an automated data processing system for questionnaires, heart rate, physical activity and posture.

PubMed

Fukuda, H; Takahashi, M; Miki, K; Haratani, T; Kurabayashi, L; Hisanaga, N; Arito, H; Takahashi, H; Egoshi, M; Sakurai, M

1999-04-01

To assess the shift work-related problems associated with a 16-h night shift in a two-shift system, we took the following important factors into consideration; the interaction between circadian rhythms and the longer night shift, the type of morningness and eveningness experienced, the subjective sleep feeling, the subjects' daily behavior, the effectiveness of taking a nap during the long night shift, and finally the effectiveness of using several different kinds of measuring devices. Included among the measuring devices used were a standard questionnaire, repetitive self-assessment of subjective symptoms and daily behavior at short intervals, and a continuous recording of such objective indices as physical activity and heart rate. A potential problem lies in the fact that field studies that use such measures tend to produce a mass of data, and are thus faced with the accompanying technical problem of analyzing such a large amount of data (time, effort and cost). To solve the data analysis problem, we developed an automated data processing system. Through the use of an image scanner with a paper feeder, standard paper, an optical character recognition function and common application software, we were able to analyze a mass of data continuously and automatically within a short time. Our system should prove useful for field studies that produce a large amount of data collected with several different kinds of measuring devices.

Stereovision-based integrated system for point cloud reconstruction and simulated brain shift validation.

PubMed

Yang, Xiaochen; Clements, Logan W; Luo, Ma; Narasimhan, Saramati; Thompson, Reid C; Dawant, Benoit M; Miga, Michael I

2017-07-01

Intraoperative soft tissue deformation, referred to as brain shift, compromises the application of current image-guided surgery navigation systems in neurosurgery. A computational model driven by sparse data has been proposed as a cost-effective method to compensate for cortical surface and volumetric displacements. We present a mock environment developed to acquire stereoimages from a tracked operating microscope and to reconstruct three-dimensional point clouds from these images. A reconstruction error of 1 mm is estimated by using a phantom with a known geometry and independently measured deformation extent. The microscope is tracked via an attached tracking rigid body that facilitates the recording of the position of the microscope via a commercial optical tracking system as it moves during the procedure. Point clouds, reconstructed under different microscope positions, are registered into the same space to compute the feature displacements. Using our mock craniotomy device, realistic cortical deformations are generated. When comparing our tracked microscope stereo-pair measure of mock vessel displacements to that of the measurement determined by the independent optically tracked stylus marking, the displacement error was [Formula: see text] on average. These results demonstrate the practicality of using tracked stereoscopic microscope as an alternative to laser range scanners to collect sufficient intraoperative information for brain shift correction.

Confocal imaging of transmembrane voltage by SEER of di-8-ANEPPS

PubMed Central

Manno, Carlo; Figueroa, Lourdes; Fitts, Robert

2013-01-01

Imaging, optical mapping, and optical multisite recording of transmembrane potential (Vm) are essential for studying excitable cells and systems. The naphthylstyryl voltage-sensitive dyes, including di-8-ANEPPS, shift both their fluorescence excitation and emission spectra upon changes in Vm. Accordingly, they have been used for monitoring Vm in nonratioing and both emission and excitation ratioing modes. Their changes in fluorescence are usually much less than 10% per 100 mV. Conventional ratioing increases sensitivity to between 3 and 15% per 100 mV. Low sensitivity limits the value of these dyes, especially when imaged with low light systems like confocal scanners. Here we demonstrate the improvement afforded by shifted excitation and emission ratioing (SEER) as applied to imaging membrane potential in flexor digitorum brevis muscle fibers of adult mice. SEER—the ratioing of two images of fluorescence, obtained with different excitation wavelengths in different emission bands—was implemented in two commercial confocal systems. A conventional pinhole scanner, affording optimal setting of emission bands but less than ideal excitation wavelengths, achieved a sensitivity of up to 27% per 100 mV, nearly doubling the value found by conventional ratioing of the same data. A better pair of excitation lights should increase the sensitivity further, to 35% per 100 mV. The maximum acquisition rate with this system was 1 kHz. A fast “slit scanner” increased the effective rate to 8 kHz, but sensitivity was lower. In its high-sensitivity implementation, the technique demonstrated progressive deterioration of action potentials upon fatiguing tetani induced by stimulation patterns at >40 Hz, thereby identifying action potential decay as a contributor to fatigue onset. Using the fast implementation, we could image for the first time an action potential simultaneously at multiple locations along the t-tubule system. These images resolved the radially varying lag associated with propagation at a finite velocity. PMID:23440278

Confocal imaging of transmembrane voltage by SEER of di-8-ANEPPS.

PubMed

Manno, Carlo; Figueroa, Lourdes; Fitts, Robert; Ríos, Eduardo

2013-03-01

Imaging, optical mapping, and optical multisite recording of transmembrane potential (V(m)) are essential for studying excitable cells and systems. The naphthylstyryl voltage-sensitive dyes, including di-8-ANEPPS, shift both their fluorescence excitation and emission spectra upon changes in V(m). Accordingly, they have been used for monitoring V(m) in nonratioing and both emission and excitation ratioing modes. Their changes in fluorescence are usually much less than 10% per 100 mV. Conventional ratioing increases sensitivity to between 3 and 15% per 100 mV. Low sensitivity limits the value of these dyes, especially when imaged with low light systems like confocal scanners. Here we demonstrate the improvement afforded by shifted excitation and emission ratioing (SEER) as applied to imaging membrane potential in flexor digitorum brevis muscle fibers of adult mice. SEER--the ratioing of two images of fluorescence, obtained with different excitation wavelengths in different emission bands-was implemented in two commercial confocal systems. A conventional pinhole scanner, affording optimal setting of emission bands but less than ideal excitation wavelengths, achieved a sensitivity of up to 27% per 100 mV, nearly doubling the value found by conventional ratioing of the same data. A better pair of excitation lights should increase the sensitivity further, to 35% per 100 mV. The maximum acquisition rate with this system was 1 kHz. A fast "slit scanner" increased the effective rate to 8 kHz, but sensitivity was lower. In its high-sensitivity implementation, the technique demonstrated progressive deterioration of action potentials upon fatiguing tetani induced by stimulation patterns at >40 Hz, thereby identifying action potential decay as a contributor to fatigue onset. Using the fast implementation, we could image for the first time an action potential simultaneously at multiple locations along the t-tubule system. These images resolved the radially varying lag associated with propagation at a finite velocity.

Complex phase error and motion estimation in synthetic aperture radar imaging

NASA Astrophysics Data System (ADS)

Soumekh, M.; Yang, H.

1991-06-01

Attention is given to a SAR wave equation-based system model that accurately represents the interaction of the impinging radar signal with the target to be imaged. The model is used to estimate the complex phase error across the synthesized aperture from the measured corrupted SAR data by combining the two wave equation models governing the collected SAR data at two temporal frequencies of the radar signal. The SAR system model shows that the motion of an object in a static scene results in coupled Doppler shifts in both the temporal frequency domain and the spatial frequency domain of the synthetic aperture. The velocity of the moving object is estimated through these two Doppler shifts. It is shown that once the dynamic target's velocity is known, its reconstruction can be formulated via a squint-mode SAR geometry with parameters that depend upon the dynamic target's velocity.

Verification of the linac isocenter for stereotactic radiosurgery using cine-EPID imaging and arc delivery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rowshanfarzad, Pejman; Sabet, Mahsheed; O' Connor, Daryl J.

2011-07-15

Purpose:Verification of the mechanical isocenter position is required as part of comprehensive quality assurance programs for stereotactic radiosurgery/radiotherapy (SRS/SRT) treatments. Several techniques have been proposed for this purpose but each of them has certain drawbacks. In this paper, a new efficient and more comprehensive method using cine-EPID images has been introduced for automatic verification of the isocenter with sufficient accuracy for stereotactic applications. Methods: Using a circular collimator fixed to the gantry head to define the field, EPID images of a Winston-Lutz phantom were acquired in cine-imaging mode during 360 deg. gantry rotations. A robust matlab code was developed tomore » analyze the data by finding the center of the field and the center of the ball bearing shadow in each image with sub-pixel accuracy. The distance between these two centers was determined for every image. The method was evaluated by comparison to results of a mechanical pointer and also by detection of a manual shift applied to the phantom position. The repeatability and reproducibility of the method were tested and it was also applied to detect couch and collimator wobble during rotation. Results:The accuracy of the algorithm was 0.03 {+-} 0.02 mm. The repeatability was less than 3 {mu}m and the reproducibility was less than 86 {mu}m. The time elapsed for the analysis of more than 100 cine images of Varian aS1000 and aS500 EPIDs were {approx}65 and 20 s, respectively. Processing of images taken in integrated mode took 0.1 s. The output of the analysis software is printable and shows the isocenter shifts as a function of angle in both in-plane and cross-plane directions. It gives warning messages where the shifts exceed the criteria for SRS/SRT and provides useful data for the necessary adjustments in the system including bearing system and/or room lasers. Conclusions: The comprehensive method introduced in this study uses cine-images, is highly accurate, fast, and independent of the observer. It tests all gantry angles and is suitable for pretreatment QA of the isocenter for stereotactic treatments.« less

Overview of TAMU-CC Unmanned Aircraft Systems Coastal Research in the Port Mansfield Area, June 2015

NASA Astrophysics Data System (ADS)

Starek, M. J.; Bridges, D. H.

2016-02-01

In June, 2015, the TAMU-CC Unmanned Aircraft Systems Program, with the support of the Lone Star UAS Center of Excellence and Innovation, conducted a week-long UAS exercise in the coastal region near Port Mansfield, Texas. The platform used was TAMU-CC's RS-16, a variant of the Arcturus T-16XL, that was equipped with a three-camera imaging system which acquired high-resolution images in the optical range of the electromagnetic spectrum and lower resolution images in the infrared and ultraviolet ranges of the spectrum. The RS-16 has a wingspan of 12.9 ft, a typical take-off weight of 70 lbs, and a typical cruising speed of 60 kt. A total of 9 flights were conducted over 7 days, with a total of 22.9 flight hours. Different areas of interest were mapped for different researchers investigating specific coastal phenomena. This poster will describe the overall operational aspects of the exercise. The aircraft and imaging system will be described in detail, as will the operational procedures and subsequent data reduction procedures. The process of selection of the coastal regions for investigation and the flight planning involved in mapping those regions will be discussed. A summary of the resulting image data will be presented.

Chromatic Image Analysis For Quantitative Thermal Mapping

NASA Technical Reports Server (NTRS)

Buck, Gregory M.

1995-01-01

Chromatic image analysis system (CIAS) developed for use in noncontact measurements of temperatures on aerothermodynamic models in hypersonic wind tunnels. Based on concept of temperature coupled to shift in color spectrum for optical measurement. Video camera images fluorescence emitted by phosphor-coated model at two wavelengths. Temperature map of model then computed from relative brightnesses in video images of model at those wavelengths. Eliminates need for intrusive, time-consuming, contact temperature measurements by gauges, making it possible to map temperatures on complex surfaces in timely manner and at reduced cost.

Null test fourier domain alignment technique for phase-shifting point diffraction interferometer

DOEpatents

Naulleau, Patrick; Goldberg, Kenneth Alan

2000-01-01

Alignment technique for calibrating a phase-shifting point diffraction interferometer involves three independent steps where the first two steps independently align the image points and pinholes in rotation and separation to a fixed reference coordinate system, e.g, CCD. Once the two sub-elements have been properly aligned to the reference in two parameters (separation and orientation), the third step is to align the two sub-element coordinate systems to each other in the two remaining parameters (x,y) using standard methods of locating the pinholes relative to some easy to find reference point.

A Burkholderia pseudomallei colony variant necessary for gastric colonization.

PubMed

Austin, C R; Goodyear, A W; Bartek, I L; Stewart, A; Sutherland, M D; Silva, E B; Zweifel, A; Vitko, N P; Tuanyok, A; Highnam, G; Mittelman, D; Keim, P; Schweizer, H P; Vázquez-Torres, A; Dow, S W C; Voskuil, M I

2015-02-03

Diverse colony morphologies are a hallmark of Burkholderia pseudomallei recovered from infected patients. We observed that stresses that inhibit aerobic respiration shifted populations of B. pseudomallei from the canonical white colony morphotype toward two distinct, reversible, yet relatively stable yellow colony variants (YA and YB). As accumulating evidence supports the importance of B. pseudomallei enteric infection and gastric colonization, we tested the response of yellow variants to hypoxia, acidity, and stomach colonization. Yellow variants exhibited a competitive advantage under hypoxic and acidic conditions and alkalized culture media. The YB variant, although highly attenuated in acute virulence, was the only form capable of colonization and persistence in the murine stomach. The accumulation of extracellular DNA (eDNA) was a characteristic of YB as observed by 4',6-diamidino-2-phenylindole (DAPI) staining of gastric tissues, as well as in an in vitro stomach model where large amounts of eDNA were produced without cell lysis. Transposon mutagenesis identified a transcriptional regulator (BPSL1887, designated YelR) that when overexpressed produced the yellow phenotype. Deletion of yelR blocked a shift from white to the yellow forms. These data demonstrate that YB is a unique B. pseudomallei pathovariant controlled by YelR that is specifically adapted to the harsh gastric environment and necessary for persistent stomach colonization. Seemingly uniform populations of bacteria often contain subpopulations that are genetically identical but display unique characteristics which offer advantages when the population is faced with infrequent but predictable stresses. The pathogen Burkholderia pseudomallei is capable of forming several reversible colony types, and it interconverted between one white type and two yellow types under certain environmental stresses. The two yellow forms exhibited distinct advantages in low-oxygen and acidic environments. One yellow colony variant was the only form capable of chronic stomach colonization. Areas of gastric infection were marked by bacteria encased in a DNA matrix, and the yellow forms were able to produce large amounts of extracellular DNA in vitro. We also identified the regulator in control of yellow colony variant formation. These findings demonstrate a role in infection for colony variation and provide a mechanism for chronic stomach colonization-a frequently overlooked niche in melioidosis. Copyright © 2015 Austin et al.

Incorporation of DPP6a and DPP6K variants in ternary Kv4 channel complex reconstitutes properties of A-type K current in rat cerebellar granule cells.

PubMed

Jerng, Henry H; Pfaffinger, Paul J

2012-01-01

Dipeptidyl peptidase-like protein 6 (DPP6) proteins co-assemble with Kv4 channel α-subunits and Kv channel-interacting proteins (KChIPs) to form channel protein complexes underlying neuronal somatodendritic A-type potassium current (I(SA)). DPP6 proteins are expressed as N-terminal variants (DPP6a, DPP6K, DPP6S, DPP6L) that result from alternative mRNA initiation and exhibit overlapping expression patterns. Here, we study the role DPP6 variants play in shaping the functional properties of I(SA) found in cerebellar granule (CG) cells using quantitative RT-PCR and voltage-clamp recordings of whole-cell currents from reconstituted channel complexes and native I(SA) channels. Differential expression of DPP6 variants was detected in rat CG cells, with DPP6K (41 ± 3%)>DPP6a (33 ± 3%)>DPP6S (18 ± 2%)>DPP6L (8 ± 3%). To better understand how DPP6 variants shape native neuronal I(SA), we focused on studying interactions between the two dominant variants, DPP6K and DPP6a. Although previous studies did not identify unique functional effects of DPP6K, we find that the unique N-terminus of DPP6K modulates the effects of KChIP proteins, slowing recovery and producing a negative shift in the steady-state inactivation curve. By contrast, DPP6a uses its distinct N-terminus to directly confer rapid N-type inactivation independently of KChIP3a. When DPP6a and DPP6K are co-expressed in ratios similar to those found in CG cells, their distinct effects compete in modulating channel function. The more rapid inactivation from DPP6a dominates during strong depolarization; however, DPP6K produces a negative shift in the steady-state inactivation curve and introduces a slow phase of recovery from inactivation. A direct comparison to the native CG cell I(SA) shows that these mixed effects are present in the native channels. Our results support the hypothesis that the precise expression and co-assembly of different auxiliary subunit variants are important factors in shaping the I(SA) functional properties in specific neuronal populations.

Nonlinear adaptive optics: aberration correction in three photon fluorescence microscopy for mouse brain imaging

NASA Astrophysics Data System (ADS)

Sinefeld, David; Paudel, Hari P.; Wang, Tianyu; Wang, Mengran; Ouzounov, Dimitre G.; Bifano, Thomas G.; Xu, Chris

2017-02-01

Multiphoton fluorescence microscopy is a well-established technique for deep-tissue imaging with subcellular resolution. Three-photon microscopy (3PM) when combined with long wavelength excitation was shown to allow deeper imaging than two-photon microscopy (2PM) in biological tissues, such as mouse brain, because out-of-focus background light can be further reduced due to the higher order nonlinear excitation. As was demonstrated in 2PM systems, imaging depth and resolution can be improved by aberration correction using adaptive optics (AO) techniques which are based on shaping the scanning beam using a spatial light modulator (SLM). In this way, it is possible to compensate for tissue low order aberration and to some extent, to compensate for tissue scattering. Here, we present a 3PM AO microscopy system for brain imaging. Soliton self-frequency shift is used to create a femtosecond source at 1675 nm and a microelectromechanical (MEMS) SLM serves as the wavefront shaping device. We perturb the 1020 segment SLM using a modified nonlinear version of three-point phase shifting interferometry. The nonlinearity of the fluorescence signal used for feedback ensures that the signal is increasing when the spot size decreases, allowing compensation of phase errors in an iterative optimization process without direct phase measurement. We compare the performance for different orders of nonlinear feedback, showing an exponential growth in signal improvement as the nonlinear order increases. We demonstrate the impact of the method by applying the 3PM AO system for in-vivo mouse brain imaging, showing improvement in signal at 1-mm depth inside the brain.

Screening of Variations in CD22 Gene in Children with B-Precursor Acute Lymphoblastic Leukemia.

PubMed

Aslar Oner, Deniz; Akin, Dilara Fatma; Sipahi, Kadir; Mumcuoglu, Mine; Ezer, Ustun; Kürekci, A Emin; Akar, Nejat

2016-09-01

CD22 is expressed on the surface of B-cell lineage cells from the early progenitor stage of pro-B cell until terminal differentiation to mature B cells. It plays a role in signal transduction and as a regulator of B-cell receptor signaling in B-cell development. We aimed to screen exons 9-14 of the CD22 gene, which is a mutational hot spot region in B-precursor acute lymphoblastic leukemia (pre-B ALL) patients, to find possible genetic variants that could play role in the pathogenesis of pre-B ALL in Turkish children. This study included 109 Turkish children with pre-B ALL who were diagnosed at Losante Hospital for Children with Leukemia. Genomic DNA was extracted from both peripheral blood and bone marrow leukocytes. Gene amplification was performed with PCR, and all samples were screened for the variants by single strand conformation polymorphism. Samples showing band shifts were sequenced on an automated sequencer. In our patient group a total of 9 variants were identified in the CD22 gene by sequencing: a novel variant in intron 10 (T2199G); a missense variant in exon 12; 5 intronic variants between exon 12 and intron 13; a novel intronic variant (C2424T); and a synonymous in exon 13. Thirteen of 109 children (11.9%) carried the T2199G novel intronic variant located in intron 10, and 17 of 109 children (15.6%) carried the C2424T novel intronic variant. Novel variants in the CD22 gene in children with pre-B ALL in Turkey that are not present, in the Human Gene Mutation Database or NCBI SNP database, were found.

Target recognition and phase acquisition by using incoherent digital holographic imaging

NASA Astrophysics Data System (ADS)

Lee, Munseob; Lee, Byung-Tak

2017-05-01

In this study, we proposed the Incoherent Digital Holographic Imaging (IDHI) for recognition and phase information of dedicated target. Although recent development of a number of target recognition techniques such as LIDAR, there have limited success in target discrimination, in part due to low-resolution, low scanning speed, and computation power. In the paper, the proposed system consists of the incoherent light source, such as LED, Michelson interferometer, and digital CCD for acquisition of four phase shifting image. First of all, to compare with relative coherence, we used a source as laser and LED, respectively. Through numerical reconstruction by using the four phase shifting method and Fresnel diffraction method, we recovered the intensity and phase image of USAF resolution target apart from about 1.0m distance. In this experiment, we show 1.2 times improvement in resolution compared to conventional imaging. Finally, to confirm the recognition result of camouflaged targets with the same color from background, we carry out to test holographic imaging in incoherent light. In this result, we showed the possibility of a target detection and recognition that used three dimensional shape and size signatures, numerical distance from phase information of obtained holographic image.

Three-Dimensional Microwave Imaging for Indoor Environments

NASA Astrophysics Data System (ADS)

Scott, Simon

Microwave imaging involves the use of antenna arrays, operating at microwave and millimeter-wave frequencies, for capturing images of real-world objects. Typically, one or more antennas in the array illuminate the scene with a radio-frequency (RF) signal. Part of this signal reflects back to the other antennas, which record both the amplitude and phase of the reflected signal. These reflected RF signals are then processed to form an image of the scene. This work focuses on using planar antenna arrays, operating between 17 and 26 GHz, to capture three-dimensional images of people and other objects inside a room. Such an imaging system enables applications such as indoor positioning and tracking, health monitoring and hand gesture recognition. Microwave imaging techniques based on beamforming cannot be used for indoor imaging, as most objects lie within the array near-field. Therefore, the range-migration algorithm (RMA) is used instead, as it compensates for the curvature of the reflected wavefronts, hence enabling near-field imaging. It is also based on fast-Fourier transforms and is therefore computationally efficient. A number of novel RMA variants were developed to support a wider variety of antenna array configurations, as well as to generate 3-D velocity maps of objects moving around a room. The choice of antenna array configuration, microwave transceiver components and transmit power has a significant effect on both the energy consumed by the imaging system and the quality of the resulting images. A generic microwave imaging testbed was therefore built to characterize the effect of these antenna array parameters on image quality in the 20 GHz band. All variants of the RMA were compared and found to produce good quality three-dimensional images with transmit power levels as low as 1 muW. With an array size of 80x80 antennas, most of the imaging algorithms were able to image objects at 0.5 m range with 12.5 mm resolution, although some were only able to achieve 20 mm resolution. Increasing the size of the antenna array further results in a proportional improvement in image resolution and image SNR, until the resolution reaches the half-wavelength limit. While microwave imaging is not a new technology, it has seen little commercial success due to the cost and power consumption of the large number of antennas and radio transceivers required to build such a system. The cost and power consumption can be reduced by using low-power and low-cost components in both the transmit and receive RF chains, even if these components have poor noise figures. Alternatively, the cost and power consumption can be reduced by decreasing the number of antennas in the array, while keeping the aperture constant. This reduction in antenna count is achieved by randomly depopulating the array, resulting in a sparse antenna array. A novel compressive sensing algorithm, coupled with the wavelet transform, is used to process the samples collected by the sparse array and form a 3-D image of the scene. This algorithm works well for antenna arrays that are up to 96% sparse, equating to a 25 times reduction in the number of required antennas. For microwave imaging to be useful, it needs to capture images of the scene in real time. The architecture of a system capable of capturing real-time 3-D microwave images is therefore designed. The system consists of a modular antenna array, constructed by plugging RF daughtercards into a carrier board. Each daughtercard is a self-contained radio system, containing an antenna, RF transceiver baseband signal chain, and analog-to-digital converters. A small number of daughtercards have been built, and proven to be suitable for real-time microwave imaging. By arranging these daughtercards in different ways, any antenna array pattern can be built. This architecture allows real-time microwave imaging systems to be rapidly prototyped, while still being able to generate images at video frame rates.

Alkynyl-naphthalimide Fluorophores: Gold Coordination Chemistry and Cellular Imaging Applications.

PubMed

Langdon-Jones, Emily E; Lloyd, David; Hayes, Anthony J; Wainwright, Shane D; Mottram, Huw J; Coles, Simon J; Horton, Peter N; Pope, Simon J A

2015-07-06

A range of fluorescent alkynyl-naphthalimide fluorophores has been synthesized and their photophysical properties examined. The fluorescent ligands are based upon a 4-substituted 1,8-naphthalimide core and incorporate structural variations (at the 4-position) to tune the amphiphilic character: chloro (L1), 4-[2-(2-aminoethoxy)ethanol] (L2), 4-[2-(2-methoxyethoxy)ethylamino] (L3), piperidine (L4), morpholine (L5), 4-methylpiperidine (L6), and 4-piperidone ethylene ketal (L7) variants. The amino-substituted species (L2-L7) are fluorescent in the visible region at around 517-535 nm through a naphthalimide-localized intramolecular charge transfer (ICT), with appreciable Stokes' shifts of ca. 6500 cm(-1) and lifetimes up to 10.4 ns. Corresponding two-coordinate Au(I) complexes [Au(L)(PPh3)] were isolated, with X-ray structural studies revealing the expected coordination mode via the alkyne donor. The Au(I) complexes retain the visible fluorescence associated with the coordinated alkynyl-naphthalimide ligand. The ligands and complexes were investigated for their cytotoxicity across a range of cell lines (LOVO, MCF-7, A549, PC3, HEK) and their potential as cell imaging agents for HEK (human embryonic kidney) cells and Spironucleus vortens using confocal fluorescence microscopy. The images reveal that these fluorophores are highly compatible with fluorescence microscopy and show some clear intracellular localization patterns that are dependent upon the specific nature of the naphthalimide substituent.

Detection and prevalence of variant sciatic nerve anatomy in relation to the piriformis muscle on MRI.

PubMed

Varenika, Vanja; Lutz, Amelie M; Beaulieu, Christopher F; Bucknor, Matthew D

2017-06-01

To determine whether known variant anatomical relationships between the sciatic nerve and piriformis muscle can be identified on routine MRI studies of the hip and to establish their imaging prevalence. Hip MRI studies acquired over a period of 4 years at two medical centers underwent retrospective interpretation. Anatomical relationship between the sciatic nerve and the piriformis muscle was categorized according to the Beaton and Anson classification system. The presence of a split sciatic nerve at the level of the ischial tuberosity was also recorded. A total of 755 consecutive scans were reviewed. Conventional anatomy (type I), in which an undivided sciatic nerve passes below the piriformis muscle, was identified in 87% of cases. The remaining 13% of cases demonstrated a type II pattern in which one division of the sciatic nerve passes through the piriformis whereas the second passes below. Only two other instances of variant anatomy were identified (both type III). Most variant cases were associated with a split sciatic nerve at the level of the ischial tuberosity (73 out of 111, 65.8%). By contrast, only 6% of cases demonstrated a split sciatic nerve at this level in the context of otherwise conventional anatomy. Anatomical variations of the sciatic nerve course in relation to the piriformis muscle are frequently identified on routine MRI of the hips, occurring in 12-20% of scans reviewed. Almost all variants identified were type II. The ability to recognize variant sciatic nerve courses on MRI may prove useful in optimal treatment planning.

MO-G-BRE-03: Automated Continuous Monitoring of Patient Setup with Second-Check Independent Image Registration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, X; Fox, T; Schreibmann, E

2014-06-15

Purpose: To create a non-supervised quality assurance program to monitor image-based patient setup. The system acts a secondary check by independently computing shifts and rotations and interfaces with Varian's database to verify therapist's work and warn against sub-optimal setups. Methods: Temporary digitally-reconstructed radiographs (DRRs) and OBI radiographic image files created by Varian's treatment console during patient setup are intercepted and used as input in an independent registration module customized for accuracy that determines the optimal rotations and shifts. To deal with the poor quality of OBI images, a histogram equalization of the live images to the DDR counterparts is performedmore » as a pre-processing step. A search for the most sensitive metric was performed by plotting search spaces subject to various translations and convergence analysis was applied to ensure the optimizer finds the global minima. Final system configuration uses the NCC metric with 150 histogram bins and a one plus one optimizer running for 2000 iterations with customized scales for translations and rotations in a multi-stage optimization setup that first corrects and translations and subsequently rotations. Results: The system was installed clinically to monitor and provide almost real-time feedback on patient positioning. On a 2 month-basis uncorrected pitch values were of a mean 0.016° with standard deviation of 1.692°, and couch rotations of − 0.090°± 1.547°. The couch shifts were −0.157°±0.466° cm for the vertical, 0.045°±0.286 laterally and 0.084°± 0.501° longitudinally. Uncorrected pitch angles were the most common source of discrepancies. Large variations in the pitch angles were correlated with patient motion inside the mask. Conclusion: A system for automated quality assurance of therapist's registration was designed and tested in clinical practice. The approach complements the clinical software's automated registration in terms of algorithm configuration and performance and constitutes a practical approach to implement safe and cost-effective radiotherapy.« less

Adaptive ISAR Imaging of Maneuvering Targets Based on a Modified Fourier Transform.

PubMed

Wang, Binbin; Xu, Shiyou; Wu, Wenzhen; Hu, Pengjiang; Chen, Zengping

2018-04-27

Focusing on the inverse synthetic aperture radar (ISAR) imaging of maneuvering targets, this paper presents a new imaging method which works well when the target's maneuvering is not too severe. After translational motion compensation, we describe the equivalent rotation of maneuvering targets by two variables-the relative chirp rate of the linear frequency modulated (LFM) signal and the Doppler focus shift. The first variable indicates the target's motion status, and the second one represents the possible residual error of the translational motion compensation. With them, a modified Fourier transform matrix is constructed and then used for cross-range compression. Consequently, the imaging of maneuvering is converted into a two-dimensional parameter optimization problem in which a stable and clear ISAR image is guaranteed. A gradient descent optimization scheme is employed to obtain the accurate relative chirp rate and Doppler focus shift. Moreover, we designed an efficient and robust initialization process for the gradient descent method, thus, the well-focused ISAR images of maneuvering targets can be achieved adaptively. Human intervention is not needed, and it is quite convenient for practical ISAR imaging systems. Compared to precedent imaging methods, the new method achieves better imaging quality under reasonable computational cost. Simulation results are provided to validate the effectiveness and advantages of the proposed method.

Threshold multi-secret sharing scheme based on phase-shifting interferometry

NASA Astrophysics Data System (ADS)

Deng, Xiaopeng; Wen, Wei; Shi, Zhengang

2017-03-01

A threshold multi-secret sharing scheme is proposed based on phase-shifting interferometry. The K secret images to be shared are firstly encoded by using Fourier transformation, respectively. Then, these encoded images are shared into many shadow images based on recording principle of the phase-shifting interferometry. In the recovering stage, the secret images can be restored by combining any 2 K + 1 or more shadow images, while any 2 K or fewer shadow images cannot obtain any information about the secret images. As a result, a (2 K + 1 , N) threshold multi-secret sharing scheme can be implemented. Simulation results are presented to demonstrate the feasibility of the proposed method.

Immobilization precision of a modified GTC frame.

PubMed

Winey, Brian; Daartz, Juliane; Dankers, Frank; Bussière, Marc

2012-05-10

The purpose of this study was to evaluate and quantify the interfraction reproducibility and intrafraction immobilization precision of a modified GTC frame. The error of the patient alignment and imaging systems were measured using a cranial skull phantom, with simulated, predetermined shifts. The kV setup images were acquired with a room-mounted set of kV sources and panels. Calculated translations and rotations provided by the computer alignment software relying upon three implanted fiducials were compared to the known shifts, and the accuracy of the imaging and positioning systems was calculated. Orthogonal kV setup images for 45 proton SRT patients and 1002 fractions (average 22.3 fractions/patient) were analyzed for interfraction and intrafraction immobilization precision using a modified GTC frame. The modified frame employs a radiotransparent carbon cup and molded pillow to allow for more treatment angles from posterior directions for cranial lesions. Patients and the phantom were aligned with three 1.5 mm stainless steel fiducials implanted into the skull. The accuracy and variance of the patient positioning and imaging systems were measured to be 0.10 ± 0.06 mm, with the maximum uncertainty of rotation being ±0.07°. 957 pairs of interfraction image sets and 974 intrafraction image sets were analyzed. 3D translations and rotations were recorded. The 3D vector interfraction setup reproducibility was 0.13 mm ± 1.8 mm for translations and the largest uncertainty of ± 1.07º for rotations. The intrafraction immobilization efficacy was 0.19 mm ± 0.66 mm for translations and the largest uncertainty of ± 0.50º for rotations. The modified GTC frame provides reproducible setup and effective intrafraction immobilization, while allowing for the complete range of entrance angles from the posterior direction.

Kinematic model for the space-variant image motion of star sensors under dynamical conditions

NASA Astrophysics Data System (ADS)

Liu, Chao-Shan; Hu, Lai-Hong; Liu, Guang-Bin; Yang, Bo; Li, Ai-Jun

2015-06-01

A kinematic description of a star spot in the focal plane is presented for star sensors under dynamical conditions, which involves all necessary parameters such as the image motion, velocity, and attitude parameters of the vehicle. Stars at different locations of the focal plane correspond to the slightly different orientation and extent of motion blur, which characterize the space-variant point spread function. Finally, the image motion, the energy distribution, and centroid extraction are numerically investigated using the kinematic model under dynamic conditions. A centroid error of eight successive iterations <0.002 pixel is used as the termination criterion for the Richardson-Lucy deconvolution algorithm. The kinematic model of a star sensor is useful for evaluating the compensation algorithms of motion-blurred images.

Measurement of body joint angles for physical therapy based on mean shift tracking using two low cost Kinect images.

PubMed

Chen, Y C; Lee, H J; Lin, K H

2015-08-01

Range of motion (ROM) is commonly used to assess a patient's joint function in physical therapy. Because motion capture systems are generally very expensive, physical therapists mostly use simple rulers to measure patients' joint angles in clinical diagnosis, which will suffer from low accuracy, low reliability, and subjective. In this study we used color and depth image feature from two sets of low-cost Microsoft Kinect to reconstruct 3D joint positions, and then calculate moveable joint angles to assess the ROM. A Gaussian background model is first used to segment the human body from the depth images. The 3D coordinates of the joints are reconstructed from both color and depth images. To track the location of joints throughout the sequence more precisely, we adopt the mean shift algorithm to find out the center of voxels upon the joints. The two sets of Kinect are placed three meters away from each other and facing to the subject. The joint moveable angles and the motion data are calculated from the position of joints frame by frame. To verify the results of our system, we take the results from a motion capture system called VICON as golden standard. Our 150 test results showed that the deviation of joint moveable angles between those obtained by VICON and our system is about 4 to 8 degree in six different upper limb exercises, which are acceptable in clinical environment.

Fast computational scheme of image compression for 32-bit microprocessors

NASA Technical Reports Server (NTRS)

Kasperovich, Leonid

1994-01-01

This paper presents a new computational scheme of image compression based on the discrete cosine transform (DCT), underlying JPEG and MPEG International Standards. The algorithm for the 2-d DCT computation uses integer operations (register shifts and additions / subtractions only); its computational complexity is about 8 additions per image pixel. As a meaningful example of an on-board image compression application we consider the software implementation of the algorithm for the Mars Rover (Marsokhod, in Russian) imaging system being developed as a part of Mars-96 International Space Project. It's shown that fast software solution for 32-bit microprocessors may compete with the DCT-based image compression hardware.

Evaluation of visual acuity with Gen 3 night vision goggles

NASA Technical Reports Server (NTRS)

Bradley, Arthur; Kaiser, Mary K.

1994-01-01

Using laboratory simulations, visual performance was measured at luminance and night vision imaging system (NVIS) radiance levels typically encountered in the natural nocturnal environment. Comparisons were made between visual performance with unaided vision and that observed with subjects using image intensification. An Amplified Night Vision Imaging System (ANVIS6) binocular image intensifier was used. Light levels available in the experiments (using video display technology and filters) were matched to those of reflecting objects illuminated by representative night-sky conditions (e.g., full moon, starlight). Results show that as expected, the precipitous decline in foveal acuity experienced with decreasing mesopic luminance levels is effectively shifted to much lower light levels by use of an image intensification system. The benefits of intensification are most pronounced foveally, but still observable at 20 deg eccentricity. Binocularity provides a small improvement in visual acuity under both intensified and unintensified conditions.

Poster — Thur Eve — 13: Inter-Fraction Target Movement in Image-Guided Radiation Therapy of Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, Congwu; Zeng, Grace G.; Department of Radiation Oncology, University of Toronto, Toronto, ON

2014-08-15

We investigated the setup variations over the treatment courses of 113 patients with intact prostate treated with 78Gy/39fx. Institutional standard bladder and bowel preparation and image guidance protocols were used in CT simulation and treatment. The RapidArc treatment plans were optimized in Varian Eclipse treatment planning system and delivered on Varian 2100X Clinacs equipped with On-Board Imager to localize the target before beam-on. The setup variations were calculated in terms of mean and standard deviation of couch shifts. No correlation was observed between the mean shift and standard deviation over the treatment course and patient age, initial prostate volume andmore » rectum size. The mean shifts in the first and last 5 fractions are highly correlated (P < 10{sup −10}) while the correlation of the standard deviations cannot be determined. The Mann-Kendall tests indicate trends of the mean daily Ant-Post and Sup-Inf shifts of the group. The target is inferior by ∼1mm to the planned position when the treatment starts and moves superiorly, approaching the planned position at 10th fraction, and then gradually moves back inferiorly by ∼1mm in the remain fractions. In the Ant-Post direction, the prostate gradually moves posteriorly during the treatment course from a mean shift of ∼2.5mm in the first fraction to ∼1mm in the last fraction. It may be related to a systematic rectum size change in the progress of treatment. The biased mean shifts in Ant-Post and Sup-Inf direction of most patients suggest systematically larger rectum and smaller bladder during the treatment than at CT simulation.« less

Serotonergic and dopaminergic modulation of attentional processes.

PubMed

Boulougouris, Vasileios; Tsaltas, Eleftheria

2008-01-01

Disturbances in attentional processes are a common feature of several psychiatric disorders such as schizophrenia, attention deficit/hyperactivity disorder and Huntington's disease. The use of animal models has been useful in defining various candidate neural systems thus enabling us to translate basic laboratory science to the clinic and vice-versa. In this chapter, a comparative and integrated account is provided on the neuroanatomical and neurochemical modulation of basic behavioural operations such as selective attention, vigilance, set-shifting and executive control focusing on the comparative functions of the serotonin and dopamine systems in the cognitive control exerted by the prefrontal cortex. Specifically, we have reviewed evidence emerging from several behavioural paradigms in experimental animals and humans each of which centres on a different aspect of the attentional function. These paradigms offering both human and animal variants include the five-choice serial reaction time task (5CSRTT), attentional set-shifting and stop-signal reaction time task. In each case, the types of operation that are measured by the given paradigm and their neural correlates are defined. Then, the role of the ascending dopaminergic and serotonergic systems in the neurochemical modulation of its behavioural output are examined, and reference is made to clinical implications for neurological and neuropsychiatric disorders which exhibit deficits in these cognitive tests.

[Fusion of MRI, fMRI and intraoperative MRI data. Methods and clinical significance exemplified by neurosurgical interventions].

PubMed

Moche, M; Busse, H; Dannenberg, C; Schulz, T; Schmitgen, A; Trantakis, C; Winkler, D; Schmidt, F; Kahn, T

2001-11-01

The aim of this work was to realize and clinically evaluate an image fusion platform for the integration of preoperative MRI and fMRI data into the intraoperative images of an interventional MRI system with a focus on neurosurgical procedures. A vertically open 0.5 T MRI scanner was equipped with a dedicated navigation system enabling the registration of additional imaging modalities (MRI, fMRI, CT) with the intraoperatively acquired data sets. These merged image data served as the basis for interventional planning and multimodal navigation. So far, the system has been used in 70 neurosurgical interventions (13 of which involved image data fusion--requiring 15 minutes extra time). The augmented navigation system is characterized by a higher frame rate and a higher image quality as compared to the system-integrated navigation based on continuously acquired (near) real time images. Patient movement and tissue shifts can be immediately detected by monitoring the morphological differences between both navigation scenes. The multimodal image fusion allowed a refined navigation planning especially for the resection of deeply seated brain lesions or pathologies close to eloquent areas. Augmented intraoperative orientation and instrument guidance improve the safety and accuracy of neurosurgical interventions.

Nonuniformity correction of imaging systems with a spatially nonhomogeneous radiation source.

PubMed

Gutschwager, Berndt; Hollandt, Jörg

2015-12-20

We present a novel method of nonuniformity correction of imaging systems in a wide optical spectral range by applying a radiation source with an unknown and spatially nonhomogeneous radiance or radiance temperature distribution. The benefit of this method is that it can be applied with radiation sources of arbitrary spatial radiance or radiance temperature distribution and only requires the sufficient temporal stability of this distribution during the measurement process. The method is based on the recording of several (at least three) images of a radiation source and a purposeful row- and line-shift of these sequent images in relation to the first primary image. The mathematical procedure is explained in detail. Its numerical verification with a source of a predefined nonhomogenous radiance distribution and a thermal imager of a predefined nonuniform focal plane array responsivity is presented.

Lateral geniculate lesions block circadian phase-shift responses to a benzodiazepine.

PubMed Central

Johnson, R F; Smale, L; Moore, R Y; Morin, L P

1988-01-01

Several pharmacological treatments, including application of an excitatory neurotoxin to the lateral geniculate nucleus (LGN) and systemic administration of triazolam, a clinically effective benzodiazepine, can elicit large phase shifts in a circadian rhythm according to the time of administration. The hypothesis that the LGN might mediate the effect of triazolam on circadian clock function was tested. Bilateral lesions of the LGN, which destroyed the connection from the intergeniculate leaflet to the suprachiasmatic nucleus, blocked phase-shift responses to triazolam. The requirement of an intact LGN for triazolam to shift circadian phase suggests that the LGN may be a site through which stimuli gain access to the circadian clock to modulate rhythm phase and entrainment. Images PMID:3293053

Survey of computer vision technology for UVA navigation

NASA Astrophysics Data System (ADS)

Xie, Bo; Fan, Xiang; Li, Sijian

2017-11-01

Navigation based on computer version technology, which has the characteristics of strong independence, high precision and is not susceptible to electrical interference, has attracted more and more attention in the filed of UAV navigation research. Early navigation project based on computer version technology mainly applied to autonomous ground robot. In recent years, the visual navigation system is widely applied to unmanned machine, deep space detector and underwater robot. That further stimulate the research of integrated navigation algorithm based on computer version technology. In China, with many types of UAV development and two lunar exploration, the three phase of the project started, there has been significant progress in the study of visual navigation. The paper expounds the development of navigation based on computer version technology in the filed of UAV navigation research and draw a conclusion that visual navigation is mainly applied to three aspects as follows.(1) Acquisition of UAV navigation parameters. The parameters, including UAV attitude, position and velocity information could be got according to the relationship between the images from sensors and carrier's attitude, the relationship between instant matching images and the reference images and the relationship between carrier's velocity and characteristics of sequential images.(2) Autonomous obstacle avoidance. There are many ways to achieve obstacle avoidance in UAV navigation. The methods based on computer version technology ,including feature matching, template matching, image frames and so on, are mainly introduced. (3) The target tracking, positioning. Using the obtained images, UAV position is calculated by using optical flow method, MeanShift algorithm, CamShift algorithm, Kalman filtering and particle filter algotithm. The paper expounds three kinds of mainstream visual system. (1) High speed visual system. It uses parallel structure, with which image detection and processing are carried out at high speed. The system is applied to rapid response system. (2) The visual system of distributed network. There are several discrete image data acquisition sensor in different locations, which transmit image data to the node processor to increase the sampling rate. (3) The visual system combined with observer. The system combines image sensors with the external observers to make up for lack of visual equipment. To some degree, these systems overcome lacks of the early visual system, including low frequency, low processing efficiency and strong noise. In the end, the difficulties of navigation based on computer version technology in practical application are briefly discussed. (1) Due to the huge workload of image operation , the real-time performance of the system is poor. (2) Due to the large environmental impact , the anti-interference ability of the system is poor.(3) Due to the ability to work in a particular environment, the system has poor adaptability.

Spatially variant apodization for squinted synthetic aperture radar images.

PubMed

Castillo-Rubio, Carlos F; Llorente-Romano, Sergio; Burgos-García, Mateo

2007-08-01

Spatially variant apodization (SVA) is a nonlinear sidelobe reduction technique that improves sidelobe level and preserves resolution at the same time. This method implements a bidimensional finite impulse response filter with adaptive taps depending on image information. Some papers that have been previously published analyze SVA at the Nyquist rate or at higher rates focused on strip synthetic aperture radar (SAR). This paper shows that traditional SVA techniques are useless when the sensor operates with a squint angle. The reasons for this behaviour are analyzed, and a new implementation that largely improves the results is presented. The algorithm is applied to simulated SAR images in order to demonstrate the good quality achieved along with efficient computation.

Implemented a wireless communication system for VGA capsule endoscope.

PubMed

Moon, Yeon-Kwan; Lee, Jyung Hyun; Park, Hee-Joon; Cho, Jin-Ho; Choi, Hyun-Chul

2014-01-01

Recently, several medical devices that use wireless communication are under development. In this paper, the small size frequency shift keying (FSK) transmitter and a monofilar antenna for the capsule endoscope, enabling the medical device to transmit VGA-size images of the intestine. To verify the functionality of the proposed wireless communication system, computer simulations and animal experiments were performed with the implemented capsule endoscope that includes the proposed wireless communication system. Several fundamental experiments are carried out using the implemented transmitter and antenna, and animal in-vivo experiments were performed to verify VGA image transmission.

Classification of variant forms of haemoglobin according to the ratio of glycated haemoglobin to glycated albumin.

PubMed

Miyazaki, Ayako; Kohzuma, Takuji; Kasayama, Soji; Koga, Masafumi

2012-09-01

Asymptomatic variant haemoglobin is increasingly being found in the measurement of glycated haemoglobin (HbA(1c)) for the management of diabetes mellitus. We compared the HbA(1c) concentrations measured by high-performance liquid chromatography (HPLC) and immunoassay and glycated albumin (GA) concentrations and calculated the respective ratios in order to classify the variant haemoglobin. Twenty different haemoglobin variants from 43 subjects were identified by mass spectrometry and DNA analysis. Since GA accurately reflects glycaemic control in patients with variant haemoglobin, we calculated respective ratios of HbA(1c) and GA. Haemoglobin variants causing a low ratio of HbA(1c) measured by HPLC (HPLC-HbA(1c)) to GA with a normal ratio of HbA(1c) measured by immunoassay (IA-HbA(1c)) to GA were classified as C1. A further classification of α and β was used with abnormalities of the α chain or β chain in the haemoglobin gene. Other haemoglobin variants were classified as non-C1. Eight diabetic patients with stable glycaemic control were used as controls. Twenty forms of variant haemoglobins were classified as C1α (2 variants; I-Interlaken and Hb J-Meerut), C1β (15 variants) and non-C1 (3 variants; Hb Himeji, Hb Woolwich, Hb Peterborough). Positive correlations between GA and HPLC-HbA(1c) or IA-HbA(1c) were seen in the C1β patients with diabetes mellitus. The regression line between GA and HPLC-HbA(1c), but not that between GA and IA-HbA(1c), showed a downward shift in comparison with the data obtained from the diabetic controls. Variant haemoglobin could be classified by calculating the ratios of HPLC-HbA(1c), IA-HbA(1c) and GA.

Coma measurement by transmission image sensor with a PSM

NASA Astrophysics Data System (ADS)

Wang, Fan; Wang, Xiangzhao; Ma, Mingying; Zhang, Dongqing; Shi, Weijie; Hu, Jianming

2005-01-01

As feature size decreases, especially with the use of resolution enhancement technique such as off axis illumination and phase shifting mask, fast and accurate in-situ measurement of coma has become very important in improving the performance of modern lithographic tools. The measurement of coma can be achieved by the transmission image sensor, which is an aerial image measurement device. The coma can be determined by measuring the positions of the aerial image at multiple illumination settings. In the present paper, we improve the measurement accuracy of the above technique with an alternating phase shifting mask. Using the scalar diffraction theory, we analyze the effect of coma on the aerial image. To analyze the effect of the alternating phase shifting mask, we compare the pupil filling of the mark used in the above technique with that of the phase-shifted mark used in the new technique. We calculate the coma-induced image displacements of the marks at multiple partial coherence and NA settings, using the PROLITH simulation program. The simulation results show that the accuracy of coma measurement can increase approximately 20 percent using the alternating phase shifting mask.

Accurate and fiducial-marker-free correction for three-dimensional chromatic shift in biological fluorescence microscopy.

PubMed

Matsuda, Atsushi; Schermelleh, Lothar; Hirano, Yasuhiro; Haraguchi, Tokuko; Hiraoka, Yasushi

2018-05-15

Correction of chromatic shift is necessary for precise registration of multicolor fluorescence images of biological specimens. New emerging technologies in fluorescence microscopy with increasing spatial resolution and penetration depth have prompted the need for more accurate methods to correct chromatic aberration. However, the amount of chromatic shift of the region of interest in biological samples often deviates from the theoretical prediction because of unknown dispersion in the biological samples. To measure and correct chromatic shift in biological samples, we developed a quadrisection phase correlation approach to computationally calculate translation, rotation, and magnification from reference images. Furthermore, to account for local chromatic shifts, images are split into smaller elements, for which the phase correlation between channels is measured individually and corrected accordingly. We implemented this method in an easy-to-use open-source software package, called Chromagnon, that is able to correct shifts with a 3D accuracy of approximately 15 nm. Applying this software, we quantified the level of uncertainty in chromatic shift correction, depending on the imaging modality used, and for different existing calibration methods, along with the proposed one. Finally, we provide guidelines to choose the optimal chromatic shift registration method for any given situation.

Improvement of unbalanced illumination induced telecentricity within the exposure slit

NASA Astrophysics Data System (ADS)

Jang, Jonghoon; Lee, ByeongSoo; Kang, Young Seog; Chang, Chansam; Kong, Jeong-Heung; Kim, Young Ha; Bouman, Wim; de Graaf, Roelof; Weichselbaum, Stefan; Droste, Richard; de Boeij, Wim P.; van Bussel, Bart; Neefs, Patrick; Rijke, Arij

2016-03-01

Adjustment and control of the illumination pupil asymmetry is relevant for wafer alignment and overlay of lithography tools. Pupil asymmetries can cause a tilt in aerial image (Aerial Image Tilt, or AIT). This AIT, combined with a focus offset, leads to a horizontal image shift. Pupil asymmetries can be related to a shift of the entire illumination pupil (geometrical telecentricity) caused by illuminator misalign. Another type of pupil asymmetry is energetic imbalance (quantified by pupil Center of Gravity, COG). The scanner can show pupil variation across the exposure slit. In general the COG at the edge of the slit is often worse than in the center part of the slit. Recently, ASML has released the NXT:1980Di that is equipped with an enhanced illuminator to improve pupil COG variation across the slit. In this paper we explore the performance of this scanner system and show that the AIT variation across the slit is also reduced significantly.

Digital fringe projection for hand surface coordinate variation analysis caused by osteoarthritis

NASA Astrophysics Data System (ADS)

Nor Haimi, Wan Mokhdzani Wan; Hau Tan, Cheek; Retnasamy, Vithyacharan; Vairavan, Rajendaran; Sauli, Zaliman; Roshidah Yusof, Nor; Hambali, Nor Azura Malini Ahmad; Aziz, Muhammad Hafiz Ab; Bakhit, Ahmad Syahir Ahmad

2017-11-01

Hand osteoarthritis is one of the most common forms of arthritis which impact millions of people worldwide. The disabling problem occurs when the protective cartilage on the boundaries of bones wear off over time. Currently, in order to identify hand osteoarthritis, special instruments namely X-ray scanning and MRI are used for the detection but it also has its limitations such as radiation exposure and can be quite costly. In this work, an optical metrology system based on digital fringe projection which comprises of an LCD projector, CCD camera and a personal computer has been developed to anticipate abnormal growth or deformation on the joints of the hand which are common symptoms of osteoarthritis. The main concept of this optical metrology system is to apply structured light as imaging source for surface change detection. The imaging source utilizes fringe patterns generated by C++ programming and is shifted by 3 phase shifts based on the 3 steps 2 shifts method. Phase wrapping technique and analysis were applied in order to detect the deformation of live subjects. The result has demonstrated a successful method of hand deformation detection based on the pixel tracking differences of a normal and deformed state.

Poster — Thur Eve — 18: Cherenkov Emission By High-Energy Radiation Therapy Beams: A Characterization Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zlateva, Y.; El Naqa, I.; Quitoriano, N.

2014-08-15

We investigate Cherenkov emission (CE) by radiotherapy beams via radiation dose-versus-CE correlation analyses, CE detection optimization by means of a spectral shift towards the near-infrared (NIR) window of biological tissue, and comparison of CE to on-board MV imaging. Dose-CE correlation was investigated via simulation and experiment. A Monte Carlo (MC) CE simulator was designed using Geant4. Experimental phantoms include: water; tissue-simulating phantom composed of water, Intralipid®, and beef blood; plastic phantom with solid water insert. The detector system comprises an optical fiber and diffraction-grating spectrometer incorporating a front/back-illuminated CCD. The NIR shift was carried out with CdSe/ZnS quantum dots (QDs),more » emitting at (650±10) nm. CE and MV images were acquired with a CMOS camera and electronic portal imaging device. MC and experimental studies indicate a strong linear dose-CE correlation (Pearson coefficient > 0.99). CE by an 18-MeV beam was effectively NIR-shifted in water and a tissue-simulating phantom, exhibiting a significant increase at 650 nm for QD depths up to 10 mm. CE images exhibited relative contrast superior to MV images by a factor of 30. Our work supports the potential for application of CE in radiotherapy online imaging for patient setup and treatment verification, since CE is intrinsic to the beam and non-ionizing and QDs can be used to improve CE detectability, potentially yielding image quality superior to MV imaging for the case of low-density-variability, low-optical-attenuation materials (ex: breast/oropharynx). Ongoing work involves microenvironment functionalization of QDs and application of multi-channel spectrometry for simultaneous acquisition of dosimetric and tumor oxygenation signals.« less

Multi-system verification of registrations for image-guided radiotherapy in clinical trials.

PubMed

Cui, Yunfeng; Galvin, James M; Straube, William L; Bosch, Walter R; Purdy, James A; Li, X Allen; Xiao, Ying

2011-09-01

To provide quantitative information on the image registration differences from multiple systems for image-guided radiotherapy (IGRT) credentialing and margin reduction in clinical trials. Images and IGRT shift results from three different treatment systems (Tomotherapy Hi-Art, Elekta Synergy, Varian Trilogy) have been sent from various institutions to the Image-Guided Therapy QA Center (ITC) for evaluation for the Radiation Therapy Oncology Group (RTOG) trials. Nine patient datasets (five head-and-neck and four prostate) were included in the comparison, with each patient having 1-4 daily individual IGRT studies. In all cases, daily shifts were re-calculated by re-registration of the planning CT with the daily IGRT data using three independent software systems (MIMvista, FocalSim, VelocityAI). Automatic fusion was used in all calculations. The results were compared with those submitted from institutions. Similar regions of interest (ROIs) and same initial positions were used in registrations for inter-system comparison. Different slice spacings for CBCT sampling and different ROIs for registration were used in some cases to observe the variation of registration due to these factors. For the 54 comparisons with head-and-neck datasets, the absolute values of differences of the registration results between different systems were 2.6±2.1 mm (mean±SD; range 0.1-8.6 mm, left-right [LR]), 1.7±1.3 mm (0.0-4.9 mm, superior-inferior [SI]), and 1.8±1.1 mm (0.1-4.0 mm, anterior-posterior [AP]). For the 66 comparisons in prostate cases, the differences were 1.1±1.0 mm (0.0-4.6 mm, LR), 2.1±1.7 mm (0.0-6.6 mm, SI), and 2.0±1.8 mm (0.1-6.9 mm, AP). The differences caused by the slice spacing variation were relatively small, and the different ROI selections in FocalSim and MIMvista also had limited impact. The extent of differences was reported when different systems were used for image registration. Careful examination and quality assurance of the image registration process are crucial before considering margin reduction using IGRT in clinical trials. Copyright © 2011 Elsevier Inc. All rights reserved.

Method comparison of ultrasound and kilovoltage x-ray fiducial marker imaging for prostate radiotherapy targeting

NASA Astrophysics Data System (ADS)

Fuller, Clifton David; Thomas, Charles R., Jr.; Schwartz, Scott; Golden, Nanalei; Ting, Joe; Wong, Adrian; Erdogmus, Deniz; Scarbrough, Todd J.

2006-10-01

Several measurement techniques have been developed to address the capability for target volume reduction via target localization in image-guided radiotherapy; among these have been ultrasound (US) and fiducial marker (FM) software-assisted localization. In order to assess interchangeability between methods, US and FM localization were compared using established techniques for determination of agreement between measurement methods when a 'gold-standard' comparator does not exist, after performing both techniques daily on a sequential series of patients. At least 3 days prior to CT simulation, four gold seeds were placed within the prostate. FM software-assisted localization utilized the ExacTrac X-Ray 6D (BrainLab AG, Germany) kVp x-ray image acquisition system to determine prostate position; US prostate targeting was performed on each patient using the SonArray (Varian, Palo Alto, CA). Patients were aligned daily using laser alignment of skin marks. Directional shifts were then calculated by each respective system in the X, Y and Z dimensions before each daily treatment fraction, previous to any treatment or couch adjustment, as well as a composite vector of displacement. Directional shift agreement in each axis was compared using Altman-Bland limits of agreement, Lin's concordance coefficient with Partik's grading schema, and Deming orthogonal bias-weighted correlation methodology. 1019 software-assisted shifts were suggested by US and FM in 39 patients. The 95% limits of agreement in X, Y and Z axes were ±9.4 mm, ±11.3 mm and ±13.4, respectively. Three-dimensionally, measurements agreed within 13.4 mm in 95% of all paired measures. In all axes, concordance was graded as 'poor' or 'unacceptable'. Deming regression detected proportional bias in both directional axes and three-dimensional vectors. Our data suggest substantial differences between US and FM image-guided measures and subsequent suggested directional shifts. Analysis reveals that the vast majority of all individual US and FM directional measures may be expected to agree with each other within a range of 1-1.5 cm. Since neither system represents a gold standard, clinical judgment must dictate whether such a difference is of import. As IMRT protocols seek dose escalation and PTV reduction predicated on US- and FM-guided imaging, future studies are needed to address these potential clinically relevant issues regarding the interchangeability and accuracy of novel positional verification techniques. Comparison series with multiple image-guidance systems are needed to refine comparisons between targeting methods. However, we do not advocate interchangeability of US and FM localization methods. Portions of this data were presented at the American Society of Clinical Oncology/American Society for Therapeutic Radiology and Oncology/Society of Surgical Oncology 2006 Prostate Cancer Symposium, San Francisco, CA, USA.

A new detection method for the K variant of butyrylcholinesterase based on PCR primer introduced restriction analysis (PCR-PIRA).

PubMed Central

Shibuta, K; Abe, M; Suzuki, T

1994-01-01

The K variant of human butyrylcholinesterase is caused by a G/A transition in the butyrylcholinesterase gene, which neither creates nor destroys any restriction site. In an attempt to detect the K variant both simply and rapidly, we developed a two step method of "PCR primer introduced restriction analysis" (PCR-PIRA). The first step was used to introduce a new Fun4HI site into the normal allele for a screening test, while the second step was performed to create a new MaeIII site on the variant allele for a specific test. This method thus enabled us to distinguish clearly the K variant from the normal allele, and also showed that the frequency of the K variant allele is 0.164 in the Japanese population. Images PMID:7966197

Adaptive bit plane quadtree-based block truncation coding for image compression

NASA Astrophysics Data System (ADS)

Li, Shenda; Wang, Jin; Zhu, Qing

2018-04-01

Block truncation coding (BTC) is a fast image compression technique applied in spatial domain. Traditional BTC and its variants mainly focus on reducing computational complexity for low bit rate compression, at the cost of lower quality of decoded images, especially for images with rich texture. To solve this problem, in this paper, a quadtree-based block truncation coding algorithm combined with adaptive bit plane transmission is proposed. First, the direction of edge in each block is detected using Sobel operator. For the block with minimal size, adaptive bit plane is utilized to optimize the BTC, which depends on its MSE loss encoded by absolute moment block truncation coding (AMBTC). Extensive experimental results show that our method gains 0.85 dB PSNR on average compare to some other state-of-the-art BTC variants. So it is desirable for real time image compression applications.

Force generation within tissues during development

NASA Astrophysics Data System (ADS)

Kasza, Karen

During embryonic development, multicellular tissues physically change shape, move, and grow. Changes in epithelial tissue organization are often accomplished by local movements of cells that are driven largely by forces generated by the motor protein myosin II. These forces are patterned to orient cell movements, resulting in changes in tissue shape and organization to build functional tissues and organs. To investigate the mechanisms of force generation in vivo, we use the fruit fly embryo as a model system. Spatial patterns of forces orient cell movements to drive rapid tissue elongation along the head-to-tail axis of the embryo. I will describe how studying embryos generated with engineered myosin variants provides insight into where, when, and how forces are generated to efficiently reorganize tissues. We found that a myosin variant that is locked-in to the active or ``on'' state accelerates cell movements, while two mutant myosin variants associated with human disease produce slowed cell movement. These myosin variants all disrupt tissue elongation, but live imaging and biophysical measurements reveal distinct effects on myosin organization and dynamics within cells and uncover mechanisms that control the spatial and temporal patterns of force generation. These studies shed light not only on how defects in force generation contribute to disease but also on physical principles at work in active, living materials.

EUV phase-shifting masks and aberration monitors

NASA Astrophysics Data System (ADS)

Deng, Yunfei; Neureuther, Andrew R.

2002-07-01

Rigorous electromagnetic simulation with TEMPEST is used to examine the use of phase-shifting masks in EUV lithography. The effects of oblique incident illumination and mask patterning by ion-mixing of multilayers are analyzed. Oblique incident illumination causes streamers at absorber edges and causes position shifting in aerial images. The diffraction waves between ion-mixed and pristine multilayers are observed. The phase-shifting caused by stepped substrates is simulated and images show that it succeeds in creation of phase-shifting effects. The diffraction process at the phase boundary is also analyzed. As an example of EUV phase-shifting masks, a coma pattern and probe based aberration monitor is simulated and aerial images are formed under different levels of coma aberration. The probe signal rises quickly as coma increases as designed.

Imaging oxytocin × dopamine interactions: an epistasis effect of CD38 and COMT gene variants influences the impact of oxytocin on amygdala activation to social stimuli

PubMed Central

Sauer, Carina; Montag, Christian; Reuter, Martin; Kirsch, Peter

2013-01-01

Although oxytocin (OT) has become a major target for the investigation of positive social processes, it can be assumed that it exerts its effects in concert with other neurotransmitters. One candidate for such an interaction is dopamine (DA). For both systems, genetic variants have been identified that influence the availability of the particular substance. A variant of the gene coding for the transmembrane protein CD38 (rs3796863), which is engaged in OT secretion, has been associated with OT plasma level. The common catechol-O-methyltransferase (COMT) val158met polymorphism is known to influence COMT activity and therefore the degradation of DA. The present study aimed to investigate OT × DA interactions in the context of an OT challenge study. Hence, we tested the influence of the above mentioned genetic variants and their interaction on the activation of different brain regions (amygdala, VTA, ventral striatum and fusiform gyrus) during the presentation of social stimuli. In a pharmacological cross-over design 55 participants were investigated under OT and placebo (PLA) by means of fMRI. Brain imaging results revealed no significant effects for VTA or ventral striatum. Regarding the fusiform gyrus, we could not find any effects apart from those already described in Sauer et al. (2012). Analyses of amygdala activation resulted in no gene main effect, no gene × substance interaction but a significant gene × gene × substance interaction. While under PLA the effect of CD38 on bilateral amygdala activation to social stimuli was modulated by the COMT genotype, no such epistasis effect was found under OT. Our results provide evidence for an OT × DA interaction during responses to social stimuli. We postulate that the effect of central OT secretion on amygdala response is modulated by the availability of DA. Therefore, for an understanding of the effect of social hormones on social behavior, interactions of OT with other transmitter systems have to be taken into account. PMID:23554586

LIPT1 deficiency presenting as early infantile epileptic encephalopathy, Leigh disease, and secondary pyruvate dehydrogenase complex deficiency.

PubMed

Stowe, Robert C; Sun, Qin; Elsea, Sarah H; Scaglia, Fernando

2018-05-01

Lipoic acid is an essential cofactor for the mitochondrial 2-ketoacid dehydrogenase complexes and the glycine cleavage system. Lipoyltransferase 1 catalyzes the covalent attachment of lipoate to these enzyme systems. Pathogenic variants in LIPT1 gene have recently been described in four patients from three families, commonly presenting with severe lactic acidosis resulting in neonatal death and/or poor neurocognitive outcomes. We report a 2-month-old male with severe lactic acidosis, refractory status epilepticus, and brain imaging suggestive of Leigh disease. Exome sequencing implicated compound heterozygous LIPT1 pathogenic variants. We describe the fifth case of LIPT1 deficiency, whose phenotype progressed to that of an early infantile epileptic encephalopathy, which is novel compared to previously described patients whom we will review. Due to the significant biochemical and phenotypic overlap that LIPT1 deficiency and mitochondrial energy cofactor disorders have with pyruvate dehydrogenase deficiency and/or nonketotic hyperglycinemia, they are and have been presumptively under-diagnosed without exome sequencing. © 2018 Wiley Periodicals, Inc.

Promoter variant -204A > C of the cholesterol 7α-hydroxylase gene: association with response to plant sterols in humans and increased transcriptional activity in transfected HepG2 cells.

PubMed

De Castro-Orós, Isabel; Pampín, Sandra; Cofán, Montserrat; Mozas, Pilar; Pintó, Xavier; Salas-Salvadó, Jordi; Rodríguez-Rey, Jose C; Ros, Emilio; Civeira, Fernando; Pocoví, Miguel

2011-04-01

The bile acid pool influences intestinal cholesterol absorption because this process is strictly dependent on micellar solubilization, which is disrupted by plant sterols (PS). Plasma lipid variation relates to promoter variant -204A > C (rs3808607) of the CYP7A1 gene encoding for 7α-hydroxylase, an enzyme for bile acid synthesis. We hypothesized that this polymorphism would be associated with variability in lipid responses to PS. We investigated 67 subjects (31 AA and 36 AC + CC) with lipid responses to PS documented in two studies. To assess the functionality of the -204A > C variant, electrophoretic mobility gel shift assays were performed and luciferase reporter plasmids containing the promoter were transfected into HepG2 cells. Compared to AA-subjects, C-carriers showed significantly higher adjusted mean reductions in total cholesterol (0.14 versus 0.43 mmol/L, P = 0.042) and increases in lathosterol-to-cholesterol ratios (0.10 versus 0.75, P = 0.013). The C-construct caused a 78% promoter activity increase and gel-shift assays showed lower affinity for nuclear transcription factors, while in silico experiments predicted a binding site for inhibitory nuclear factors RXR-CAR. Results suggest that promoter -204A > C variant is associated with enhanced CYP7A1 activity. Increased intestinal bile acids and ensuing more efficient cholesterol absorption might explain why C-allele carriers show enhanced cholesterol lowering and increased feedback cholesterol synthesis to PS intervention. Copyright © 2010 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Stabilized high-accuracy correction of ocular aberrations with liquid crystal on silicon spatial light modulator in adaptive optics retinal imaging system.

PubMed

Huang, Hongxin; Inoue, Takashi; Tanaka, Hiroshi

2011-08-01

We studied the long-term optical performance of an adaptive optics scanning laser ophthalmoscope that uses a liquid crystal on silicon spatial light modulator to correct ocular aberrations. The system achieved good compensation of aberrations while acquiring images of fine retinal structures, excepting during sudden eye movements. The residual wavefront aberrations collected over several minutes in several situations were statistically analyzed. The mean values of the root-mean-square residual wavefront errors were 23-30 nm, and for around 91-94% of the effective time the errors were below the Marechal criterion for diffraction limited imaging. The ability to axially shift the imaging plane to different retinal depths was also demonstrated.

Regionally variant collagen alignment correlates with viscoelastic properties of the disc of the human temporomandibular joint.

PubMed

Gutman, Shawn; Kim, Daniel; Tarafder, Solaiman; Velez, Sergio; Jeong, Julia; Lee, Chang H

2018-02-01

To determine the regionally variant quality of collagen alignment in human TMJ discs and its statistical correlation with viscoelastic properties. For quantitative analysis of the quality of collagen alignment, horizontal sections of human TMJ discs with Pricrosirius Red staining were imaged under circularly polarized microscopy. Mean angle and angular deviation of collagen fibers in each region were analyzed using a well-established automated image-processing for angular gradient. Instantaneous and relaxation moduli of each disc region were measured under stress-relaxation test both in tensile and compression. Then Spearman correlation analysis was performed between the angular deviation and the moduli. To understand the effect of glycosaminoglycans on the correlation, TMJ disc samples were treated by chondroitinase ABC (C-ABC). Our imaging processing analysis showed the region-variant direction of collagen alignment, consistently with previous findings. Interestingly, the quality of collagen alignment, not only the directions, was significantly different in between the regions. The angular deviation of fiber alignment in the anterior and intermediate regions were significantly smaller than the posterior region. Medial and lateral regions showed significantly bigger angular deviation than all the other regions. The regionally variant angular deviation values showed statistically significant correlation with the tensile instantaneous modulus and the relaxation modulus, partially dependent on C-ABC treatment. Our findings suggest the region-variant degree of collagen fiber alignment is likely attributed to the heterogeneous viscoelastic properties of TMJ disc that may have significant implications in development of regenerative therapy for TMJ disc. Copyright © 2017 Elsevier Ltd. All rights reserved.

X-ray structure of Cerulean GFP: a tryptophan-based chromophore useful for fluorescence lifetime imaging.

PubMed

Malo, Gabrielle D; Pouwels, Lauren J; Wang, Meitian; Weichsel, Andrzej; Montfort, William R; Rizzo, Mark A; Piston, David W; Wachter, Rebekka M

2007-09-04

The crystal structure of the cyan-fluorescent Cerulean green fluorescent protein (GFP), a variant of enhanced cyan fluorescent protein (ECFP), has been determined to 2.0 A. Cerulean bears an internal fluorophore composed of an indole moiety derived from Y66W, conjugated to the GFP-like imidazolinone ring via a methylene bridge. Cerulean undergoes highly efficient fluorescence resonance energy transfer (FRET) to yellow acceptor molecules and exhibits significantly reduced excited-state heterogeneity. This feature was rationally engineered in ECFP by substituting His148 with an aspartic acid [Rizzo et al. (2004) Nat. Biotechnol. 22, 445], rendering Cerulean useful for fluorescence lifetime imaging microscopy (FLIM). The X-ray structure is consistent with a single conformation of the chromophore and surrounding residues and may therefore provide a structural rationale for the previously described monoexponential fluorescence decay. Unexpectedly, the carboxyl group of H148D is found in a buried position, directly contacting the indole nitrogen of the chromophore via a bifurcated hydrogen bond. Compared to the similarly constructed ECFP chromophore, the indole group of Cerulean is rotated around the methylene bridge to adopt a cis-coplanar conformation with respect to the imidazolinone ring, resulting in a close edge-to-edge contact of the two ring systems. The double-humped absorbance spectrum persists in single-crystal absorbance measurements, casting doubt on the idea that ground state conformational heterogeneity forms the basis of the two overlapping transitions. At low pH, a blue shift in absorbance of 10-15 nm suggests a pH-induced structural transition that proceeds with a time constant of 47 (+/-2) min and is reversible. Possible interpretations in terms of chromophore isomerization are presented.

Anatomical and metabolic small-animal whole-body imaging using ring-shaped confocal photoacoustic computed tomography

NASA Astrophysics Data System (ADS)

Xia, Jun; Chatni, Muhammad; Maslov, Konstantin; Wang, Lihong V.

2013-03-01

Due to the wide use of animals for human disease studies, small animal whole-body imaging plays an increasingly important role in biomedical research. Currently, none of the existing imaging modalities can provide both anatomical and glucose metabolic information, leading to higher costs of building dual-modality systems. Even with image coregistration, the spatial resolution of the metabolic imaging modality is not improved. We present a ring-shaped confocal photoacoustic computed tomography (RC-PACT) system that can provide both assessments in a single modality. Utilizing the novel design of confocal full-ring light delivery and ultrasound transducer array detection, RC-PACT provides full-view cross-sectional imaging with high spatial resolution. Scanning along the orthogonal direction provides three-dimensional imaging. While the mouse anatomy was imaged with endogenous hemoglobin contrast, the glucose metabolism was imaged with a near-infrared dye-labeled 2-deoxyglucose. Through mouse tumor models, we demonstrate that RC-PACT may be a paradigm shifting imaging method for preclinical research.

Personality, Gender, and the Northern Cities Shift

ERIC Educational Resources Information Center

Johnson, Steve Leonard, III

2012-01-01

Studies of sound changes in sociolinguistics have shown a consistent trend that women tend to be linguistically innovative and lead most of the major sound changes. Additionally, women have been shown to use more standard variants than men in stable sociolinguistic variables, giving rise to the "gender paradox" where women are both…

SU-F-J-209: Quantification of Image-Guidance Benefit in Image-Guided Radiotherapy of Cancers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, L; Department of Therapeutic Radiology, Yale University, New Haven, CT; Deng, J

Purpose: Image-guidance has been widely used in radiation oncology for accurate radiotherapy. The goal of this study is to quantify the benefit of image-guidance in image-guided radiotherapy (IGRT) of cancers. Methods: In this study, a new index termed image-guidance benefit (IGB), was proposed to quantify the benefit of image-guidance in cancer radiotherapy. It is calculated as a ratio of the square sum of dose differences between planning dose matrix and actual delivery dose matrix post image-guidance to the square sum of dose summation between the two matrixes, summing over all dose scoring voxels. Ranging from 0 to 1, larger IGBmore » values indicate larger benefit out of image-guidance. With IRB approval, the DICOM RT files and 3D couch shifts applied during IGRT of 2219 patients were collected, based on which patient-specific IGB values were calculated with an in-house MATLAB code. Results: In this study, the mean IGB value was found to be 0.0398 (0.000583–0.999) with a positive correlation between IGB value and 3D couch shift vector at 0.0435 per cm (P<0.0001). With 2 mm shift as a threshold above which an image-guidance is deemed clinically necessary, the corresponding mean IGB value was 0.00457, much less than 0.0398 (P<0.001). However, the IGB values of 56 cases based on couch shifts were less than those based on 2 mm shift. Conclusion: The IGB values were patient-specific and site-dependent. Using 2 mm shifts as criterion for applying image-guidance, the applied image-guidance procedures were found clinically necessary and highly beneficial in 97.5% of cancer patients. However, image-guidance procedures were found over-used in about 2.5% of cancer patients in our current practices of IGRT, which should be avoided as they added no benefit in improving delivery accuracy while increasing cancer risk.« less

Preferential association of a functional variant in complement receptor 2 with antibodies to double-stranded DNA

PubMed Central

Zhao, Jian; Giles, Brendan M; Taylor, Rhonda L; Yette, Gabriel A; Lough, Kara M; Ng, Han Leng; Abraham, Lawrence J; Wu, Hui; Kelly, Jennifer A; Glenn, Stuart B; Adler, Adam J; Williams, Adrienne H; Comeau, Mary E; Ziegler, Julie T; Marion, Miranda; Alarcón-Riquelme, Marta E; Alarcón, Graciela S; Anaya, Juan-Manuel; Bae, Sang-Cheol; Kim, Dam; Lee, Hye-Soon; Criswell, Lindsey A; Freedman, Barry I; Gilkeson, Gary S; Guthridge, Joel M; Jacob, Chaim O; James, Judith A; Kamen, Diane L; Merrill, Joan T; Sivils, Kathy Moser; Niewold, Timothy B; Petri, Michelle A; Ramsey-Goldman, Rosalind; Reveille, John D; Scofield, R Hal; Stevens, Anne M; Vilá, Luis M; Vyse, Timothy J; Kaufman, Kenneth M; Harley, John B; Langefeld, Carl D; Gaffney, Patrick M; Brown, Elizabeth E; Edberg, Jeffrey C; Kimberly, Robert P; Ulgiati, Daniela; Tsao, Betty P; Boackle, Susan A

2016-01-01

Objectives Systemic lupus erythematosus (SLE; OMIM 152700) is characterised by the production of antibodies to nuclear antigens. We previously identified variants in complement receptor 2 (CR2/CD21) that were associated with decreased risk of SLE. This study aimed to identify the causal variant for this association. Methods Genotyped and imputed genetic variants spanning CR2 were assessed for association with SLE in 15 750 case-control subjects from four ancestral groups. Allele-specific functional effects of associated variants were determined using quantitative real-time PCR, quantitative flow cytometry, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP)-PCR. Results The strongest association signal was detected at rs1876453 in intron 1 of CR2 (pmeta=4.2×10−4, OR 0.85), specifically when subjects were stratified based on the presence of dsDNA autoantibodies (case-control pmeta=7.6×10−7, OR 0.71; case-only pmeta=1.9×10−4, OR 0.75). Although allele-specific effects on B cell CR2 mRNA or protein levels were not identified, levels of complement receptor 1 (CR1/CD35) mRNA and protein were significantly higher on B cells of subjects harbouring the minor allele (p=0.0248 and p=0.0006, respectively). The minor allele altered the formation of several DNA protein complexes by EMSA, including one containing CCCTC-binding factor (CTCF), an effect that was confirmed by ChIP-PCR. Conclusions These data suggest that rs1876453 in CR2 has long-range effects on gene regulation that decrease susceptibility to lupus. Since the minor allele at rs1876453 is preferentially associated with reduced risk of the highly specific dsDNA autoantibodies that are present in preclinical, active and severe lupus, understanding its mechanisms will have important therapeutic implications. PMID:25180293

Distinct seasonal infectious agent profiles in life-history variants of juvenile Fraser River Chinook salmon: An application of high-throughput genomic screening.

PubMed

Tucker, Strahan; Li, Shaorong; Kaukinen, Karia H; Patterson, David A; Miller, Kristina M

2018-01-01

Disease-causing infectious agents are natural components of ecosystems and considered a major selective force driving the evolution of host species. However, knowledge of the presence and abundance of suites of infectious agents in wild populations has been constrained by our ability to easily screen for them. Using salmon as a model, we contrasted seasonal pathogenic infectious agents in life history variants of juvenile Chinook salmon from the Fraser River system (N = 655), British Columbia (BC), through the application of a novel high-throughput quantitative PCR monitoring platform. This included freshwater hatchery origin fish and samples taken at sea between ocean entry in spring and over-winter residence in coastal waters. These variants currently display opposite trends in productivity, with yearling stocks generally in decline and sub-yearling stocks doing comparatively well. We detected the presence of 32 agents, 21 of which were at >1% prevalence. Variants carried a different infectious agent profile in terms of (1) diversity, (2) origin or transmission environment of infectious agents, and (3) prevalence and abundance of individual agents. Differences in profiles tended to reflect differential timing and residence patterns through freshwater, estuarine and marine habitats. Over all seasons, individual salmon carried an average of 3.7 agents. Diversity changed significantly, increasing upon saltwater entrance, increasing through the fall and decreasing slightly in winter. Diversity varied between life history types with yearling individuals carrying 1.3-times more agents on average. Shifts in prevalence and load over time were examined to identify agents with the greatest potential for impact at the stock level; those displaying concurrent decrease in prevalence and load truncation with time. Of those six that had similar patterns in both variants, five reached higher prevalence in yearling fish while only one reached higher prevalence in sub-yearling fish; this pattern was present for an additional five agents in yearling fish only.

Distinct seasonal infectious agent profiles in life-history variants of juvenile Fraser River Chinook salmon: An application of high-throughput genomic screening

PubMed Central

Li, Shaorong; Kaukinen, Karia H.; Patterson, David A.; Miller, Kristina M.

2018-01-01

Disease-causing infectious agents are natural components of ecosystems and considered a major selective force driving the evolution of host species. However, knowledge of the presence and abundance of suites of infectious agents in wild populations has been constrained by our ability to easily screen for them. Using salmon as a model, we contrasted seasonal pathogenic infectious agents in life history variants of juvenile Chinook salmon from the Fraser River system (N = 655), British Columbia (BC), through the application of a novel high-throughput quantitative PCR monitoring platform. This included freshwater hatchery origin fish and samples taken at sea between ocean entry in spring and over-winter residence in coastal waters. These variants currently display opposite trends in productivity, with yearling stocks generally in decline and sub-yearling stocks doing comparatively well. We detected the presence of 32 agents, 21 of which were at >1% prevalence. Variants carried a different infectious agent profile in terms of (1) diversity, (2) origin or transmission environment of infectious agents, and (3) prevalence and abundance of individual agents. Differences in profiles tended to reflect differential timing and residence patterns through freshwater, estuarine and marine habitats. Over all seasons, individual salmon carried an average of 3.7 agents. Diversity changed significantly, increasing upon saltwater entrance, increasing through the fall and decreasing slightly in winter. Diversity varied between life history types with yearling individuals carrying 1.3-times more agents on average. Shifts in prevalence and load over time were examined to identify agents with the greatest potential for impact at the stock level; those displaying concurrent decrease in prevalence and load truncation with time. Of those six that had similar patterns in both variants, five reached higher prevalence in yearling fish while only one reached higher prevalence in sub-yearling fish; this pattern was present for an additional five agents in yearling fish only. PMID:29672620

CCL2 and CCR2 variants are associated with skeletal muscle strength and change in strength with resistance training.

PubMed

Harmon, Brennan T; Orkunoglu-Suer, E Funda; Adham, Kasra; Larkin, Justin S; Gordish-Dressman, Heather; Clarkson, Priscilla M; Thompson, Paul D; Angelopoulos, Theodore J; Gordon, Paul M; Moyna, Niall M; Pescatello, Linda S; Visich, Paul S; Zoeller, Robert F; Hubal, Monica J; Tosi, Laura L; Hoffman, Eric P; Devaney, Joseph M

2010-12-01

Baseline muscle size and muscle adaptation to exercise are traits with high variability across individuals. Recent research has implicated several chemokines and their receptors in the pathogenesis of many conditions that are influenced by inflammatory processes, including muscle damage and repair. One specific chemokine, chemokine (C-C motif) ligand 2 (CCL2), is expressed by macrophages and muscle satellite cells, increases expression dramatically following muscle damage, and increases expression further with repeated bouts of exercise, suggesting that CCL2 plays a key role in muscle adaptation. The present study hypothesizes that genetic variations in CCL2 and its receptor (CCR2) may help explain muscle trait variability. College-aged subjects [n = 874, Functional Single-Nucleotide Polymorphisms Associated With Muscle Size and Strength (FAMUSS) cohort] underwent a 12-wk supervised strength-training program for the upper arm muscles. Muscle size (via MR imaging) and elbow flexion strength (1 repetition maximum and isometric) measurements were taken before and after training. The study participants were then genotyped for 11 genetic variants in CCL2 and five variants in CCR2. Variants in the CCL2 and CCR2 genes show strong associations with several pretraining muscle strength traits, indicating that inflammatory genes in skeletal muscle contribute to the polygenic system that determines muscle phenotypes. These associations extend across both sexes, and several of these genetic variants have been shown to influence gene regulation.

Crystal and source characterization for the Crystal Backlighter Imager capability at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Krauland, C. M.; Hall, G. N.; Buscho, J. G.; Hibbard, R.; McCarville, T. J.; Lowe-Webb, R.; Ayers, S. L.; Kalantar, D.; Kohut, T.; Kemp, G. E.; Bradley, D. K.; Bell, P.; Landen, O. L.; Brewster, T. N.; Piston, K.

2017-10-01

The Crystal Backlighter Imager (CBI) is a very narrow bandwidth ( 10 eV) x-ray radiography system that uses Bragg reflection from a spherically-curved crystal at near normal incidence. This diagnostic has the capability to image late in an ICF implosion because it only requires the brightness of the backlighter to be larger than the capsule self-emission in that narrow bandwidth. While the limited bandwidth is advantageous for this reason, it also requires that the effective energy of the backlighter atomic line is known to 1 eV accuracy for proper crystal alignment. Any Doppler shift in the line energy must be understood for the imaging system to work. The work presented details characterization experiments done at the Jupiter Laser Facility with a Si (8 6 2) crystal that will be used with a Selenium backlighter in the NIF CBI diagnostic. We used the spherically-bent crystals to image a small ( 200 µm) He α source generated by the Janus laser on a Se foil. Scanning Bragg angles over multiple shots allowed us to map out the spectral line intensity distribution for optimal alignment in NIF. A subsequent Doppler shift measurement using CBI on NIF will also be presented with complementary HYDRA modeling for both experiments. Prepared by LLNL under Contract DE-AC52-07NA27344 and by General Atomics under Contract DE-NA0001808.

Congenital anatomic variants of the kidney and ureter: a pictorial essay.

PubMed

Srinivas, M R; Adarsh, K M; Jeeson, Riya; Ashwini, C; Nagaraj, B R

2016-03-01

Congenital renal parenchymal and pelvicalyceal abnormalities have a wide spectrum. Most of them are asymptomatic, like that of ectopia, cross fused kidney, horseshoe kidney, etc., while a few of them become complicated, leading to renal failure and death. It is very important for the radiologist to identify these anatomic variants and guide the clinicians for surgical and therapeutic procedures. Cross-sectional imaging with a volume rendered technique/maximum intensity projection has overcome ultrasonography and IVU for identification and interpretation of some of these variants.

Computer assisted detection and analysis of tall cell variant papillary thyroid carcinoma in histological images

NASA Astrophysics Data System (ADS)

Kim, Edward; Baloch, Zubair; Kim, Caroline

2015-03-01

The number of new cases of thyroid cancer are dramatically increasing as incidences of this cancer have more than doubled since the early 1970s. Tall cell variant (TCV-PTC) papillary thyroid carcinoma is one type of thyroid cancer that is more aggressive and usually associated with higher local recurrence and distant metastasis. This variant can be identified through visual characteristics of cells in histological images. Thus, we created a fully automatic algorithm that is able to segment cells using a multi-stage approach. Our method learns the statistical characteristics of nuclei and cells during the segmentation process and utilizes this information for a more accurate result. Furthermore, we are able to analyze the detected regions and extract characteristic cell data that can be used to assist in clinical diagnosis.

Integral-geometry characterization of photobiomodulation effects on retinal vessel morphology

PubMed Central

Barbosa, Marconi; Natoli, Riccardo; Valter, Kriztina; Provis, Jan; Maddess, Ted

2014-01-01

The morphological characterization of quasi-planar structures represented by gray-scale images is challenging when object identification is sub-optimal due to registration artifacts. We propose two alternative procedures that enhances object identification in the integral-geometry morphological image analysis (MIA) framework. The first variant streamlines the framework by introducing an active contours segmentation process whose time step is recycled as a multi-scale parameter. In the second variant, we used the refined object identification produced in the first variant to perform the standard MIA with exact dilation radius as multi-scale parameter. Using this enhanced MIA we quantify the extent of vaso-obliteration in oxygen-induced retinopathic vascular growth, the preventative effect (by photobiomodulation) of exposure during tissue development to near-infrared light (NIR, 670 nm), and the lack of adverse effects due to exposure to NIR light. PMID:25071966

Functional characterization of four naturally occurring variants of human pregnane X receptor (PXR): one variant causes dramatic loss of both DNA binding activity and the transactivation of the CYP3A4 promoter/enhancer region.

PubMed

Koyano, Satoru; Kurose, Kouichi; Saito, Yoshiro; Ozawa, Shogo; Hasegawa, Ryuichi; Komamura, Kazuo; Ueno, Kazuyuki; Kamakura, Shiro; Kitakaze, Masafumi; Nakajima, Toshiharu; Matsumoto, Kenji; Akasawa, Akira; Saito, Hirohisa; Sawada, Jun-Ichi

2004-01-01

Metabolism of administered drugs is determined by expression and activity of many drug-metabolizing enzymes, such as the cytochrome P450 (P450s) family members. Pregnane X receptor (PXR) is a master transcriptional regulator of many drug/xenobiotic-metabolizing enzymes, including P450s and drug transporters. In this study, we describe the functional analysis of four naturally occurring human PXR (hPXR) variants (R98C, R148Q, R381W, and I403V) that we have recently identified. By a reporter gene assay using the CYP3A4 promoter/enhancer reporter in COS-7 or HepG2 cells, it was found that the R98C variant failed to transactivate the CYP3A4 reporter. The R381W and I403V variants also showed varying degrees of reduction in transactivation, depending on the dose of PXR activators, rifampicin, clotrimazole, and paclitaxel. The transcriptional activities of the R148Q variant were not significantly different from that of the wild-type hPXR. The electrophoretic mobility shift assay revealed that only the R98C variant lacked DNA binding. Furthermore, the cellular localization of the hPXR proteins was analyzed. All four variants as well as the wild-type hPXR localized exclusively to the nucleus, regardless of the presence or absence of rifampicin. These data suggest that the R98C, R381W, and I403V hPXR variants, especially R98C, may influence the expression of drug-metabolizing enzymes and transporters, which are transactivated by PXR.

Complementary role of magnetic resonance imaging in the study of the fetal urinary system.

PubMed

Gómez Huertas, M; Culiañez Casas, M; Molina García, F S; Carrillo Badillo, M P; Pastor Pons, E

2016-01-01

Urinary system birth defects represent the abnormality most often detected in prenatal studies, accounting for 30% to 50% of all structural anomalies present at birth. The most common disorders are urinary tract dilation, developmental variants, cystic kidney diseases, kidney tumors, and bladder defects. These anomalies can present in isolation or in association with various syndromes. They are normally evaluated with sonography, and the use of magnetic resonance imaging (MRI) is considered only in inconclusive cases. In this article, we show the potential of fetal MRI as a technique to complement sonography in the study of fetal urinary system anomalies. We show the additional information that MRI can provide in each entity, especially in the evaluation of kidney function through diffusion-weighted sequences. Copyright © 2016 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

[Testing method research for key performance indicator of imaging acousto-optic tunable filter (AOTF)].

PubMed

Hu, Shan-Zhou; Chen, Fen-Fei; Zeng, Li-Bo; Wu, Qiong-Shui

2013-01-01

Imaging AOTF is an important optical filter component for new spectral imaging instruments developed in recent years. The principle of imaging AOTF component was demonstrated, and a set of testing methods for some key performances were studied, such as diffraction efficiency, wavelength shift with temperature, homogeneity in space for diffraction efficiency, imaging shift, etc.

Pedestrian detection based on redundant wavelet transform

NASA Astrophysics Data System (ADS)

Huang, Lin; Ji, Liping; Hu, Ping; Yang, Tiejun

2016-10-01

Intelligent video surveillance is to analysis video or image sequences captured by a fixed or mobile surveillance camera, including moving object detection, segmentation and recognition. By using it, we can be notified immediately in an abnormal situation. Pedestrian detection plays an important role in an intelligent video surveillance system, and it is also a key technology in the field of intelligent vehicle. So pedestrian detection has very vital significance in traffic management optimization, security early warn and abnormal behavior detection. Generally, pedestrian detection can be summarized as: first to estimate moving areas; then to extract features of region of interest; finally to classify using a classifier. Redundant wavelet transform (RWT) overcomes the deficiency of shift variant of discrete wavelet transform, and it has better performance in motion estimation when compared to discrete wavelet transform. Addressing the problem of the detection of multi-pedestrian with different speed, we present an algorithm of pedestrian detection based on motion estimation using RWT, combining histogram of oriented gradients (HOG) and support vector machine (SVM). Firstly, three intensities of movement (IoM) are estimated using RWT and the corresponding areas are segmented. According to the different IoM, a region proposal (RP) is generated. Then, the features of a RP is extracted using HOG. Finally, the features are fed into a SVM trained by pedestrian databases and the final detection results are gained. Experiments show that the proposed algorithm can detect pedestrians accurately and efficiently.

SU-E-J-225: Quantitative Evaluation of Rigid and Non-Rigid Motion of Liver Tumors Using Stereo Imaging During SBRT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Q; Hanna, G; Kubicek, G

2014-06-01

Purpose: To quantitatively evaluate rigid and nonrigid motion of liver tumors based on fiducial tracking in 3D by stereo imaging during CyberKnife SBRT. Methods: Twenty-five liver patients previously treated with three-fractions of SBRT were retrospectively recruited in this study. During treatment, the 3D locations of fiducials were reported by the CyberKnife system after two orthogonal kV X-ray images were taken and further validated by geometry derivations. A total of 5004 pairs of X-ray images acquired during the course of treatment for all the patients, were analyzed. For rigid motion, the rotational angles and translational shifts by aligning 3D fiducial groupsmore » in different image pairs after least-square fitting were reported. For nonrigid motion, the relative interfractional tumor shape variations were reported and correlated to the sum of inter-fiducial distances. The individual fiducial displacements were also reported after rigid corrections and without angle corrections. Results: The relative tumor volume variation indicated by the inter-fiducial distances demonstrated an increasing trend in the second (101.6±3.4%) and third fraction (101.2±5.6%) among most patients. The cause could be possibly due to radiation-induced edema. For all the patients, the translational shift was 8.1±5.7 mm, with shifts in LR, AP and SI were 2.1±2.4 mm, 2.8±2.9 mm and 6.7±5.1 mm, respectively. The greatest translation shift occurred in SI, mainly due the breathing motion of diaphragm The rotational angles were 1.1±1.7°, 1.9±2.6° and 1.6±2.2°, in roll, pitch, and yaw, respectively. The 3D fiducial displacement with rigid corrections were 0.2±0.2 mm and increased to 0.6±0.3 mm without rotational corrections. Conclusion: The fiducial locations in 3D can be precisely reconstructed from CyberKnife stereo imaging system during treatment. The fiducials provide close estimation of both rigid and nonrigid motion of .liver tumors. The reported data could be further utilized for tumor margin design and motion management in in conventional linac-based treatments.« less

Algorithms for image recovery calculation in extended single-shot phase-shifting digital holography

NASA Astrophysics Data System (ADS)

Hasegawa, Shin-ya; Hirata, Ryo

2018-04-01

The single-shot phase-shifting method of image recovery using an inclined reference wave has the advantages of reducing the effects of vibration, being capable of operating in real time, and affording low-cost sensing. In this method, relatively low reference angles compared with that in the conventional method using phase shift between three or four pixels has been required. We propose an extended single-shot phase-shifting technique which uses the multiple-step phase-shifting algorithm and the corresponding multiple pixels which are the same as that of the period of an interference fringe. We have verified the theory underlying this recovery method by means of Fourier spectral analysis and its effectiveness by evaluating the visibility of the image using a high-resolution pattern. Finally, we have demonstrated high-contrast image recovery experimentally using a resolution chart. This method can be used in a variety of applications such as color holographic interferometry.

Research on effects of phase error in phase-shifting interferometer

NASA Astrophysics Data System (ADS)

Wang, Hongjun; Wang, Zhao; Zhao, Hong; Tian, Ailing; Liu, Bingcai

2007-12-01

Referring to phase-shifting interferometry technology, the phase shifting error from the phase shifter is the main factor that directly affects the measurement accuracy of the phase shifting interferometer. In this paper, the resources and sorts of phase shifting error were introduction, and some methods to eliminate errors were mentioned. Based on the theory of phase shifting interferometry, the effects of phase shifting error were analyzed in detail. The Liquid Crystal Display (LCD) as a new shifter has advantage as that the phase shifting can be controlled digitally without any mechanical moving and rotating element. By changing coded image displayed on LCD, the phase shifting in measuring system was induced. LCD's phase modulation characteristic was analyzed in theory and tested. Based on Fourier transform, the effect model of phase error coming from LCD was established in four-step phase shifting interferometry. And the error range was obtained. In order to reduce error, a new error compensation algorithm was put forward. With this method, the error can be obtained by process interferogram. The interferogram can be compensated, and the measurement results can be obtained by four-step phase shifting interferogram. Theoretical analysis and simulation results demonstrate the feasibility of this approach to improve measurement accuracy.

Learning without labeling: domain adaptation for ultrasound transducer localization.

PubMed

Heimann, Tobias; Mountney, Peter; John, Matthias; Ionasec, Razvan

2013-01-01

The fusion of image data from trans-esophageal echography (TEE) and X-ray fluoroscopy is attracting increasing interest in minimally-invasive treatment of structural heart disease. In order to calculate the needed transform between both imaging systems, we employ a discriminative learning based approach to localize the TEE transducer in X-ray images. Instead of time-consuming manual labeling, we generate the required training data automatically from a single volumetric image of the transducer. In order to adapt this system to real X-ray data, we use unlabeled fluoroscopy images to estimate differences in feature space density and correct covariate shift by instance weighting. An evaluation on more than 1900 images reveals that our approach reduces detection failures by 95% compared to cross validation on the test set and improves the localization error from 1.5 to 0.8 mm. Due to the automatic generation of training data, the proposed system is highly flexible and can be adapted to any medical device with minimal efforts.

Spatially variant morphological restoration and skeleton representation.

PubMed

Bouaynaya, Nidhal; Charif-Chefchaouni, Mohammed; Schonfeld, Dan

2006-11-01

The theory of spatially variant (SV) mathematical morphology is used to extend and analyze two important image processing applications: morphological image restoration and skeleton representation of binary images. For morphological image restoration, we propose the SV alternating sequential filters and SV median filters. We establish the relation of SV median filters to the basic SV morphological operators (i.e., SV erosions and SV dilations). For skeleton representation, we present a general framework for the SV morphological skeleton representation of binary images. We study the properties of the SV morphological skeleton representation and derive conditions for its invertibility. We also develop an algorithm for the implementation of the SV morphological skeleton representation of binary images. The latter algorithm is based on the optimal construction of the SV structuring element mapping designed to minimize the cardinality of the SV morphological skeleton representation. Experimental results show the dramatic improvement in the performance of the SV morphological restoration and SV morphological skeleton representation algorithms in comparison to their translation-invariant counterparts.

Two-Dimensional Signal Processing and Storage and Theory and Applications of Electromagnetic Measurements.

DTIC Science & Technology

1983-06-01

system, provides a convenient, low- noise , fully parallel method of improving contrast and enhancing structural detail in an image prior to input to a...directed towards problems in deconvolution, reconstruction from projections, bandlimited extrapolation, and shift varying deblurring of images...deconvolution algorithm has been studied with promising 5 results [I] for simulated motion blurs. Future work will focus on noise effects and the extension

Using ultrasound CBE imaging without echo shift compensation for temperature estimation.

PubMed

Tsui, Po-Hsiang; Chien, Yu-Ting; Liu, Hao-Li; Shu, Yu-Chen; Chen, Wen-Shiang

2012-09-01

Clinical trials have demonstrated that hyperthermia improves cancer treatments. Previous studies developed ultrasound temperature imaging methods, based on the changes in backscattered energy (CBE), to monitor temperature variations during hyperthermia. Echo shift, induced by increasing temperature, contaminates the CBE image, and its tracking and compensation should normally ensure that estimations of CBE at each pixel are correct. To obtain a simplified algorithm that would allow real-time computation of CBE images, this study evaluated the usefulness of CBE imaging without echo shift compensation in detecting distributions in temperature. Experiments on phantoms, using different scatterer concentrations, and porcine livers were conducted to acquire raw backscattered data at temperatures ranging from 37°C to 45°C. Tissue samples of pork tenderloin were ablated in vitro by microwave irradiation to evaluate the feasibility of using the CBE image without compensation to monitor tissue ablation. CBE image construction was based on a ratio map obtained from the envelope image divided by the reference envelope image at 37°C. The experimental results demonstrated that the CBE image obtained without echo shift compensation has the ability to estimate temperature variations induced during uniform heating or tissue ablation. The magnitude of the CBE as a function of temperature obtained without compensation is stronger than that with compensation, implying that the CBE image without compensation has a better sensitivity to detect temperature. These findings suggest that echo shift tracking and compensation may be unnecessary in practice, thus simplifying the algorithm required to implement real-time CBE imaging. Copyright © 2012 Elsevier B.V. All rights reserved.

Spatially and spectrally engineered spin-orbit interaction for achromatic virtual shaping

PubMed Central

Pu, Mingbo; Zhao, Zeyu; Wang, Yanqin; Li, Xiong; Ma, Xiaoliang; Hu, Chenggang; Wang, Changtao; Huang, Cheng; Luo, Xiangang

2015-01-01

The geometries of objects are deterministic in electromagnetic phenomena in all aspects of our world, ranging from imaging with spherical eyes to stealth aircraft with bizarre shapes. Nevertheless, shaping the physical geometry is often undesired owing to other physical constraints such as aero- and hydro-dynamics in the stealth technology. Here we demonstrate that it is possible to change the traditional law of reflection as well as the electromagnetic characters without altering the physical shape, by utilizing the achromatic phase shift stemming from spin-orbit interaction in ultrathin space-variant and spectrally engineered metasurfaces. The proposal is validated by full-wave simulations and experimental characterization in optical wavelengths ranging from 600 nm to 2800 nm and microwave frequencies in 8-16 GHz, with echo reflectance less than 10% in the whole range. The virtual shaping as well as the revised law of reflection may serve as a versatile tool in many realms, including broadband and conformal camouflage and Kinoform holography, to name just a few. PMID:25959663

Improved medical image fusion based on cascaded PCA and shift invariant wavelet transforms.

PubMed

Reena Benjamin, J; Jayasree, T

2018-02-01

In the medical field, radiologists need more informative and high-quality medical images to diagnose diseases. Image fusion plays a vital role in the field of biomedical image analysis. It aims to integrate the complementary information from multimodal images, producing a new composite image which is expected to be more informative for visual perception than any of the individual input images. The main objective of this paper is to improve the information, to preserve the edges and to enhance the quality of the fused image using cascaded principal component analysis (PCA) and shift invariant wavelet transforms. A novel image fusion technique based on cascaded PCA and shift invariant wavelet transforms is proposed in this paper. PCA in spatial domain extracts relevant information from the large dataset based on eigenvalue decomposition, and the wavelet transform operating in the complex domain with shift invariant properties brings out more directional and phase details of the image. The significance of maximum fusion rule applied in dual-tree complex wavelet transform domain enhances the average information and morphological details. The input images of the human brain of two different modalities (MRI and CT) are collected from whole brain atlas data distributed by Harvard University. Both MRI and CT images are fused using cascaded PCA and shift invariant wavelet transform method. The proposed method is evaluated based on three main key factors, namely structure preservation, edge preservation, contrast preservation. The experimental results and comparison with other existing fusion methods show the superior performance of the proposed image fusion framework in terms of visual and quantitative evaluations. In this paper, a complex wavelet-based image fusion has been discussed. The experimental results demonstrate that the proposed method enhances the directional features as well as fine edge details. Also, it reduces the redundant details, artifacts, distortions.

Cerenkov Radiation Energy Transfer (CRET) Imaging: A Novel Method for Optical Imaging of PET Isotopes in Biological Systems

PubMed Central

Dothager, Robin S.; Goiffon, Reece J.; Jackson, Erin; Harpstrite, Scott; Piwnica-Worms, David

2010-01-01

Background Positron emission tomography (PET) allows sensitive, non-invasive analysis of the distribution of radiopharmaceutical tracers labeled with positron (β+)-emitting radionuclides in small animals and humans. Upon β+ decay, the initial velocity of high-energy β+ particles can momentarily exceed the speed of light in tissue, producing Cerenkov radiation that is detectable by optical imaging, but is highly absorbed in living organisms. Principal Findings To improve optical imaging of Cerenkov radiation in biological systems, we demonstrate that Cerenkov radiation from decay of the PET isotopes 64Cu and 18F can be spectrally coupled by energy transfer to high Stokes-shift quantum nanoparticles (Qtracker705) to produce highly red-shifted photonic emissions. Efficient energy transfer was not detected with 99mTc, a predominantly γ-emitting isotope. Similar to bioluminescence resonance energy transfer (BRET) and fluorescence resonance energy transfer (FRET), herein we define the Cerenkov radiation energy transfer (CRET) ratio as the normalized quotient of light detected within a spectral window centered on the fluorophore emission divided by light detected within a spectral window of the Cerenkov radiation emission to quantify imaging signals. Optical images of solutions containing Qtracker705 nanoparticles and [18F]FDG showed CRET ratios in vitro as high as 8.8±1.1, while images of mice with subcutaneous pseudotumors impregnated with Qtracker705 following intravenous injection of [18F]FDG showed CRET ratios in vivo as high as 3.5±0.3. Conclusions Quantitative CRET imaging may afford a variety of novel optical imaging applications and activation strategies for PET radiopharmaceuticals and other isotopes in biomaterials, tissues and live animals. PMID:20949021

Cerenkov radiation energy transfer (CRET) imaging: a novel method for optical imaging of PET isotopes in biological systems.

PubMed

Dothager, Robin S; Goiffon, Reece J; Jackson, Erin; Harpstrite, Scott; Piwnica-Worms, David

2010-10-11

Positron emission tomography (PET) allows sensitive, non-invasive analysis of the distribution of radiopharmaceutical tracers labeled with positron (β(+))-emitting radionuclides in small animals and humans. Upon β(+) decay, the initial velocity of high-energy β(+) particles can momentarily exceed the speed of light in tissue, producing Cerenkov radiation that is detectable by optical imaging, but is highly absorbed in living organisms. To improve optical imaging of Cerenkov radiation in biological systems, we demonstrate that Cerenkov radiation from decay of the PET isotopes (64)Cu and (18)F can be spectrally coupled by energy transfer to high Stokes-shift quantum nanoparticles (Qtracker705) to produce highly red-shifted photonic emissions. Efficient energy transfer was not detected with (99m)Tc, a predominantly γ-emitting isotope. Similar to bioluminescence resonance energy transfer (BRET) and fluorescence resonance energy transfer (FRET), herein we define the Cerenkov radiation energy transfer (CRET) ratio as the normalized quotient of light detected within a spectral window centered on the fluorophore emission divided by light detected within a spectral window of the Cerenkov radiation emission to quantify imaging signals. Optical images of solutions containing Qtracker705 nanoparticles and [(18)F]FDG showed CRET ratios in vitro as high as 8.8±1.1, while images of mice with subcutaneous pseudotumors impregnated with Qtracker705 following intravenous injection of [(18)F]FDG showed CRET ratios in vivo as high as 3.5±0.3. Quantitative CRET imaging may afford a variety of novel optical imaging applications and activation strategies for PET radiopharmaceuticals and other isotopes in biomaterials, tissues and live animals.

Single-shot quantitative phase microscopy with color-multiplexed differential phase contrast (cDPC).

PubMed

Phillips, Zachary F; Chen, Michael; Waller, Laura

2017-01-01

We present a new technique for quantitative phase and amplitude microscopy from a single color image with coded illumination. Our system consists of a commercial brightfield microscope with one hardware modification-an inexpensive 3D printed condenser insert. The method, color-multiplexed Differential Phase Contrast (cDPC), is a single-shot variant of Differential Phase Contrast (DPC), which recovers the phase of a sample from images with asymmetric illumination. We employ partially coherent illumination to achieve resolution corresponding to 2× the objective NA. Quantitative phase can then be used to synthesize DIC and phase contrast images or extract shape and density. We demonstrate amplitude and phase recovery at camera-limited frame rates (50 fps) for various in vitro cell samples and c. elegans in a micro-fluidic channel.

Stylization levels of industrial design objects

NASA Astrophysics Data System (ADS)

Kukhta, M. S.; Sokolov, A. P.; Krauinsh, D. P.; Bouchard, C.

2017-01-01

The urgency of the research of form making problem in design is associated with the necessity of new understanding of visual culture and new approaches to design engineering representing the integration of artistic and designed problems. The aim of this research is to study the levels of stylization of design objects and dependance (relation) on the specific project objectives and existing technologies. On the ground of quantitative evaluation, the stylization measures are emphasized: figurative image, stylized image and abstract image. Theoretic conclusions are complemented by practical problem solution over creating openwork metal lantern. Variants of both the traditional mains supply of the lantern and the autonomic supply system based on solar energy were offered. The role of semantic factor, affecting the depth of perception of design objects semantic space, is represented in this paper.

Predicting primary progressive aphasias with support vector machine approaches in structural MRI data.

PubMed

Bisenius, Sandrine; Mueller, Karsten; Diehl-Schmid, Janine; Fassbender, Klaus; Grimmer, Timo; Jessen, Frank; Kassubek, Jan; Kornhuber, Johannes; Landwehrmeyer, Bernhard; Ludolph, Albert; Schneider, Anja; Anderl-Straub, Sarah; Stuke, Katharina; Danek, Adrian; Otto, Markus; Schroeter, Matthias L

2017-01-01

Primary progressive aphasia (PPA) encompasses the three subtypes nonfluent/agrammatic variant PPA, semantic variant PPA, and the logopenic variant PPA, which are characterized by distinct patterns of language difficulties and regional brain atrophy. To validate the potential of structural magnetic resonance imaging data for early individual diagnosis, we used support vector machine classification on grey matter density maps obtained by voxel-based morphometry analysis to discriminate PPA subtypes (44 patients: 16 nonfluent/agrammatic variant PPA, 17 semantic variant PPA, 11 logopenic variant PPA) from 20 healthy controls (matched for sample size, age, and gender) in the cohort of the multi-center study of the German consortium for frontotemporal lobar degeneration. Here, we compared a whole-brain with a meta-analysis-based disease-specific regions-of-interest approach for support vector machine classification. We also used support vector machine classification to discriminate the three PPA subtypes from each other. Whole brain support vector machine classification enabled a very high accuracy between 91 and 97% for identifying specific PPA subtypes vs. healthy controls, and 78/95% for the discrimination between semantic variant vs. nonfluent/agrammatic or logopenic PPA variants. Only for the discrimination between nonfluent/agrammatic and logopenic PPA variants accuracy was low with 55%. Interestingly, the regions that contributed the most to the support vector machine classification of patients corresponded largely to the regions that were atrophic in these patients as revealed by group comparisons. Although the whole brain approach took also into account regions that were not covered in the regions-of-interest approach, both approaches showed similar accuracies due to the disease-specificity of the selected networks. Conclusion, support vector machine classification of multi-center structural magnetic resonance imaging data enables prediction of PPA subtypes with a very high accuracy paving the road for its application in clinical settings.

Using satellite data in map design and production

USGS Publications Warehouse

Hutchinson, John A.

2002-01-01

Satellite image maps have been produced by the U.S. Geological Survey (USGS) since shortly after the launch of the first Landsat satellite in 1972. Over the years, the use of image data to design and produce maps has developed from a manual and photographic process to one that incorporates geographic information systems, desktop publishing, and digital prepress techniques. At the same time, the content of most image-based maps produced by the USGS has shifted from raw image data to land cover or other information layers derived from satellite imagery, often portrayed in combination with shaded relief.

Joint genetic analysis of hippocampal size in mouse and human identifies a novel gene linked to neurodegenerative disease.

PubMed

Ashbrook, David G; Williams, Robert W; Lu, Lu; Stein, Jason L; Hibar, Derrek P; Nichols, Thomas E; Medland, Sarah E; Thompson, Paul M; Hager, Reinmar

2014-10-03

Variation in hippocampal volume has been linked to significant differences in memory, behavior, and cognition among individuals. To identify genetic variants underlying such differences and associated disease phenotypes, multinational consortia such as ENIGMA have used large magnetic resonance imaging (MRI) data sets in human GWAS studies. In addition, mapping studies in mouse model systems have identified genetic variants for brain structure variation with great power. A key challenge is to understand how genetically based differences in brain structure lead to the propensity to develop specific neurological disorders. We combine the largest human GWAS of brain structure with the largest mammalian model system, the BXD recombinant inbred mouse population, to identify novel genetic targets influencing brain structure variation that are linked to increased risk for neurological disorders. We first use a novel cross-species, comparative analysis using mouse and human genetic data to identify a candidate gene, MGST3, associated with adult hippocampus size in both systems. We then establish the coregulation and function of this gene in a comprehensive systems-analysis. We find that MGST3 is associated with hippocampus size and is linked to a group of neurodegenerative disorders, such as Alzheimer's.

Gliosarcoma: A rare variant of glioblastoma multiforme in paediatric patient: Case report and review of literature

PubMed Central

Meena, Ugan Singh; Sharma, Sumit; Chopra, Sanjeev; Jain, Shashi Kant

2016-01-01

Gliosarcoma is rare central nervous system tumour and a variant of glioblastoma multiforme with bimorphic histological pattern of glial and sarcomatous differentiation. It occurs in elderly between 5th and 6th decades of life and extremely rare in children. It is highly aggressive tumour and managed like glioblastoma multiforme. A 12-year-old female child presented with complaints of headache and vomiting from 15 d and blurring of vision from 3 d. Magnetic resonance imaging of brain shows heterogeneous mass in right parieto-occipital cortex. A right parieto-occipito-temporal craniotomy with complete excision of mass revealed a primary glioblastoma on histopathological investigation. Treatment consists of maximum surgical excision followed by adjuvant radiotherapy. The etiopathogenesis, treatment modalities and prognosis is discussed. The available literature is also reviewed. PMID:27672648

Enhanced procedural learning of speech sound categories in a genetic variant of FOXP2.

PubMed

Chandrasekaran, Bharath; Yi, Han-Gyol; Blanco, Nathaniel J; McGeary, John E; Maddox, W Todd

2015-05-20

A mutation of the forkhead box protein P2 (FOXP2) gene is associated with severe deficits in human speech and language acquisition. In rodents, the humanized form of FOXP2 promotes faster switching from declarative to procedural learning strategies when the two learning systems compete. Here, we examined a polymorphism of FOXP2 (rs6980093) in humans (214 adults; 111 females) for associations with non-native speech category learning success. Neurocomputational modeling results showed that individuals with the GG genotype shifted faster to procedural learning strategies, which are optimal for the task. These findings support an adaptive role for the FOXP2 gene in modulating the function of neural learning systems that have a direct bearing on human speech category learning. Copyright © 2015 the authors 0270-6474/15/357808-05$15.00/0.

Emergence of CD134 cysteine-rich domain 2 (CRD2)-independent strains of feline immunodeficiency virus (FIV) is associated with disease progression in naturally infected cats.

PubMed

Bęczkowski, Paweł M; Techakriengkrai, Navapon; Logan, Nicola; McMonagle, Elizabeth; Litster, Annette; Willett, Brian J; Hosie, Margaret J

2014-11-28

Feline immunodeficiency virus (FIV) infection is mediated by sequential interactions with CD134 and CXCR4. Field strains of virus vary in their dependence on cysteine-rich domain 2 (CRD2) of CD134 for infection. Here, we analyse the receptor usage of viral variants in the blood of 39 naturally infected cats, revealing that CRD2-dependent viral variants dominate in early infection, evolving towards CRD2-independence with disease progression. These findings are consistent with a shift in CRD2 of CD134 usage with disease progression.

Viewing zone duplication of multi-projection 3D display system using uniaxial crystal.

PubMed

Lee, Chang-Kun; Park, Soon-Gi; Moon, Seokil; Lee, Byoungho

2016-04-18

We propose a novel multiplexing technique for increasing the viewing zone of a multi-view based multi-projection 3D display system by employing double refraction in uniaxial crystal. When linearly polarized images from projector pass through the uniaxial crystal, two possible optical paths exist according to the polarization states of image. Therefore, the optical paths of the image could be changed, and the viewing zone is shifted in a lateral direction. The polarization modulation of the image from a single projection unit enables us to generate two viewing zones at different positions. For realizing full-color images at each viewing zone, a polarization-based temporal multiplexing technique is adopted with a conventional polarization switching device of liquid crystal (LC) display. Through experiments, a prototype of a ten-view multi-projection 3D display system presenting full-colored view images is implemented by combining five laser scanning projectors, an optically clear calcite (CaCO₃) crystal, and an LC polarization rotator. For each time sequence of temporal multiplexing, the luminance distribution of the proposed system is measured and analyzed.

Characterization of the c.(-203)A>G variant in the glucocerebrosidase gene and its association with phenotype in Gaucher disease.

PubMed

Alfonso, Pilar; Pampín, Sandra; García-Rodríguez, Beatriz; Tejedor, Teresa; Domínguez, Carmen; Rodríguez-Rey, Jose C; Giraldo, Pilar; Pocoví, Miguel

2011-01-30

Gaucher disease (GD) is a rare autosomal recessive disorder caused mainly by mutations in the glucocerebrosidase (GBA) gene. Great phenotypic variability has been observed among patients with the same genotype, suggesting other factors, such as polymorphic variants, might influence GD phenotypes. We previously reported the c.(-203)A>G (g.1256A>G) variant in exon 1 of the GBA gene in Spanish GD patients. We analyzed the frequency and transcriptional activity of the promoter carrying the G-allele using restriction isotyping, electrophoretic mobility shift assay, cell culture, transfection, and luciferase assays. We found the variant is present at a similar frequency to the control group. In our patients, the G-allele was always found in combination with another mutation in the same allele, and patients carrying the c.(-203)A>G variant showed a more severe GD phenotype. The promoter containing the G-allele showed a 35% reduction in promoter activity when transfected into HepG2 cells. The c.(-203)A>G variant seems to be a polymorphism resulting in a decrease in activity of the GBA promoter. The change, per se, is not enough to elicit a GD phenotype, but it may produce a more severe phenotype in GD patients when combined with an already defective GBA protein. Copyright © 2010 Elsevier B.V. All rights reserved.

Functional Studies of Tyrosine Hydroxylase Missense Variants Reveal Distinct Patterns of Molecular Defects in Dopa-Responsive Dystonia

PubMed Central

Fossbakk, Agnete; Kleppe, Rune; Knappskog, Per M; Martinez, Aurora; Haavik, Jan

2014-01-01

Congenital tyrosine hydroxylase deficiency (THD) is found in autosomal-recessive Dopa-responsive dystonia and related neurological syndromes. The clinical manifestations of THD are variable, ranging from early-onset lethal disease to mild Parkinson disease-like symptoms appearing in adolescence. Until 2014, approximately 70 THD patients with a total of 40 different disease-related missense mutations, five nonsense mutations, and three mutations in the promoter region of the tyrosine hydroxylase (TH) gene have been reported. We collected clinical and biochemical data in the literature for all variants, and also generated mutant forms of TH variants previously not studied (N = 23). We compared the in vitro solubility, thermal stability, and kinetic properties of the TH variants to determine the cause(s) of their impaired enzyme activity, and found great heterogeneity in all these properties among the mutated forms. Some TH variants had specific kinetic anomalies and phenylalanine hydroxylase, and Dopa oxidase activities were measured for variants that showed signs of altered substrate binding. p.Arg233His, p.Gly247Ser, and p.Phe375Leu had shifted substrate specificity from tyrosine to phenylalanine and Dopa, whereas p.Cys359Phe had an impaired activity toward these substrates. The new data about pathogenic mechanisms presented are expected to contribute to develop individualized therapy for THD patients. PMID:24753243

Imaging the Gouy phase shift in photonic jets with a wavefront sensor.

PubMed

Bon, Pierre; Rolly, Brice; Bonod, Nicolas; Wenger, Jérôme; Stout, Brian; Monneret, Serge; Rigneault, Hervé

2012-09-01

A wavefront sensor is used as a direct observation tool to image the Gouy phase shift in photonic nanojets created by micrometer-sized dielectric spheres. The amplitude and phase distributions of light are found in good agreement with a rigorous electromagnetic computation. Interestingly the observed phase shift when travelling through the photonic jet is a combination of the awaited π Gouy shift and a phase shift induced by the bead refraction. Such direct spatial phase shift observation using wavefront sensors would find applications in microscopy, diffractive optics, optical trapping, and point spread function engineering.

SU-E-J-22: A Feasibility Study On KV-Based Whole Breast Radiation Patient Setup

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Q; Zhang, M; Yue, N

Purpose: In room kilovoltage x-ray (kV) imaging provides higher contrast than Megavoltage (MV) imaging with faster acquisition time compared with on-board cone-beam computed tomography (CBCT), thus improving patient setup accuracy and efficiency. In this study we evaluated the clinical feasibility of utilizing kV imaging for whole breast radiation patient setup. Methods: For six breast cancer patients with whole breast treatment plans using two opposed tangential fields, MV-based patient setup was conducted by aligning patient markers with in room lasers and MV portal images. Beam-eye viewed kV images were acquired using Varian OBI system after the set up process. In housemore » software was developed to transfer MLC blocks information overlaying onto kV images to demonstrate the field shape for verification. KV-based patient digital shift was derived by performing rigid registration between kV image and the digitally reconstructed radiography (DRR) to align the bony structure. This digital shift between kV-based and MV-based setup was defined as setup deviation. Results: Six sets of kV images were acquired for breast patients. The mean setup deviation was 2.3mm, 2.2mm and 1.8mm for anterior-posterior, superior-inferior and left-right direction respectively. The average setup deviation magnitude was 4.3±1.7mm for six patients. Patient with large breast had a larger setup deviation (4.4–6.2mm). There was no strong correlation between MV-based shift and setup deviation. Conclusion: A preliminary clinical workflow for kV-based whole breast radiation setup was established and tested. We observed setup deviation of the magnitude below than 5mm. With the benefit of providing higher contrast and MLC block overlaid on the images for treatment field verification, it is feasible to use kV imaging for breast patient setup.« less

SU-E-T-268: Proton Radiosurgery End-To-End Testing Using Lucy 3D QA Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, D; Gordon, I; Ghebremedhin, A

2014-06-01

Purpose: To check the overall accuracy of proton radiosurgery treatment delivery using ready-made circular collimator inserts and fixed thickness compensating boluses. Methods: Lucy 3D QA phantom (Standard Imaging Inc. WI, USA) inserted with GaFchromicTM film was irradiated with laterally scattered and longitudinally spread-out 126.8 MeV proton beams. The tests followed every step in the proton radiosurgery treatment delivery process: CT scan (GE Lightspeed VCT), target contouring, treatment planning (Odyssey 5.0, Optivus, CA), portal calibration, target localization using robotic couch with image guidance and dose delivery at planned gantry angles. A 2 cm diameter collimator insert in a 4 cm diametermore » radiosurgery cone and a 1.2 cm thick compensating flat bolus were used for all beams. Film dosimetry (RIT114 v5.0, Radiological Imaging Technology, CO, USA) was used to evaluate the accuracy of target localization and relative dose distributions compared to those calculated by the treatment planning system. Results: The localization accuracy was estimated by analyzing the GaFchromic films irradiated at gantry 0, 90 and 270 degrees. We observed 0.5 mm shift in lateral direction (patient left), ±0.9 mm shift in AP direction and ±1.0 mm shift in vertical direction (gantry dependent). The isodose overlays showed good agreement (<2mm, 50% isodose lines) between measured and calculated doses. Conclusion: Localization accuracy depends on gantry sag, CT resolution and distortion, DRRs from treatment planning computer, localization accuracy of image guidance system, fabrication of ready-made aperture and cone housing. The total deviation from the isocenter was 1.4 mm. Dose distribution uncertainty comes from distal end error due to bolus and CT density, in addition to localization error. The planned dose distribution was well matched (>90%) to the measured values 2%/2mm criteria. Our test showed the robustness of our proton radiosurgery treatment delivery system using ready-made collimator inserts and fixed thickness compensating boluses.« less

Holographic representation of space-variant systems: system theory.

PubMed

Marks Ii, R J; Krile, T F

1976-09-01

System theory for holographic representation of linear space-variant systems is derived. The utility of the resulting piecewise isoplanatic approximation (PIA) is illustrated by example application to the invariant system, ideal magnifier, and Fourier transformer. A method previously employed to holographically represent a space-variant system, the discrete approximation, is shown to be a special case of the PIA.

Genetic Influences on the Development of Alcoholism

PubMed Central

Enoch, Mary-Anne

2014-01-01

Alcoholism has a substantial heritability yet the detection of specific genetic influences has largely proved elusive. The strongest findings are with genes encoding alcohol metabolizing enzymes. A few candidate genes such as GABRA2 have shown robust associations with alcoholism. Moreover, it has become apparent that variants in stress-related genes such as CRHR1, may only confer risk in individuals exposed to trauma, particularly in early life. Over the past decade there have been tremendous advances in large scale SNP genotyping technologies allowing for genome-wide associations studies (GWAS). As a result, it is now recognized that genetic risk for alcoholism is likely to be due to common variants in very many genes, each of small effect, although rare variants with large effects might also play a role. This has resulted in a paradigm shift away from gene centric studies towards analyses of gene interactions and gene networks within biologically relevant pathways. PMID:24091936

Genetic influences on the development of alcoholism.

PubMed

Enoch, Mary-Anne

2013-11-01

Alcoholism has a substantial heritability yet the detection of specific genetic influences has largely proved elusive. The strongest findings are with genes encoding alcohol metabolizing enzymes. A few candidate genes such as GABRA2 have shown robust associations with alcoholism. Moreover, it has become apparent that variants in stress-related genes such as CRHR1, may only confer risk in individuals exposed to trauma, particularly in early life. Over the past decade there have been tremendous advances in large scale SNP genotyping technologies allowing for genome-wide associations studies (GWAS). As a result, it is now recognized that genetic risk for alcoholism is likely to be due to common variants in very many genes, each of small effect, although rare variants with large effects might also play a role. This has resulted in a paradigm shift away from gene centric studies toward analyses of gene interactions and gene networks within biologically relevant pathways.

Multi-site genetic analysis of diffusion images and voxelwise heritability analysis: A pilot project of the ENIGMA–DTI working group

PubMed Central

Jahanshad, Neda; Kochunov, Peter; Sprooten, Emma; Mandl, René C.; Nichols, Thomas E.; Almassy, Laura; Blangero, John; Brouwer, Rachel M.; Curran, Joanne E.; de Zubicaray, Greig I.; Duggirala, Ravi; Fox, Peter T.; Hong, L. Elliot; Landman, Bennett A.; Martin, Nicholas G.; McMahon, Katie L.; Medland, Sarah E.; Mitchell, Braxton D.; Olvera, Rene L.; Peterson, Charles P.; Starr, John M.; Sussmann, Jessika E.; Toga, Arthur W.; Wardlaw, Joanna M.; Wright, Margaret J.; Hulshoff Pol, Hilleke E.; Bastin, Mark E.; McIntosh, Andrew M.; Deary, Ian J.; Thompson, Paul M.; Glahn, David C.

2013-01-01

The ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) Consortium was set up to analyze brain measures and genotypes from multiple sites across the world to improve the power to detect genetic variants that influence the brain. Diffusion tensor imaging (DTI) yields quantitative measures sensitive to brain development and degeneration, and some common genetic variants may be associated with white matter integrity or connectivity. DTI measures, such as the fractional anisotropy (FA) of water diffusion, may be useful for identifying genetic variants that influence brain microstructure. However, genome-wide association studies (GWAS) require large populations to obtain sufficient power to detect and replicate significant effects, motivating a multi-site consortium effort. As part of an ENIGMA–DTI working group, we analyzed high-resolution FA images from multiple imaging sites across North America, Australia, and Europe, to address the challenge of harmonizing imaging data collected at multiple sites. Four hundred images of healthy adults aged 18–85 from four sites were used to create a template and corresponding skeletonized FA image as a common reference space. Using twin and pedigree samples of different ethnicities, we used our common template to evaluate the heritability of tract-derived FA measures. We show that our template is reliable for integrating multiple datasets by combining results through meta-analysis and unifying the data through exploratory mega-analyses. Our results may help prioritize regions of the FA map that are consistently influenced by additive genetic factors for future genetic discovery studies. Protocols and templates are publicly available at (http://enigma.loni.ucla.edu/ongoing/dti-working-group/). PMID:23629049

The analysis of optical-electro collimated light tube measurement system

NASA Astrophysics Data System (ADS)

Li, Zhenhui; Jiang, Tao; Cao, Guohua; Wang, Yanfei

2005-12-01

A new type of collimated light tube (CLT) is mentioned in this paper. The analysis and structure of CLT are described detail. The reticle and discrimination board are replaced by a optical-electro graphics generator, or DLP-Digital Light Processor. DLP gives all kinds of graphics controlled by computer, the lighting surface lies on the focus of the CLT. The rays of light pass through the CLT, and the tested products, the image of aim is received by variant focus objective CCD camera, the image can be processed by computer, then, some basic optical parameters will be obtained, such as optical aberration, image slope, etc. At the same time, motorized translation stage carry the DLP moving to simulate the limited distance. The grating ruler records the displacement of the DLP. The key technique is optical-electro auto-focus, the best imaging quality can be gotten by moving 6-D motorized positioning stage. Some principal questions can be solved in this device, for example, the aim generating, the structure of receiving system and optical matching.

Influence of injected interstitials on the void swelling in two structural variants of 304L stainless steel induced by self-ion irradiation at 500 °C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, C.; Garner, F. A.; Shao, L.

The two variants of AISI 304L stainless steel (SS) with different grain size distributions were ion irradiated at 500 °C to a peak dose of ~60 dpa. In the coarse-grained annealed variant, a peak swelling of ~12% was observed closer to the specimen surface rather than at the depth of peak displacement damage. The forward shift in depth between peak swelling and peak dose is proposed to be a consequence of suppression of void nucleation by injected interstitials. The swelling behavior in the front portion of the ion range mirrors that of neutron-induced swelling in this steel, exhibiting significant curvaturemore » with increasing dose as the swelling rate approaches the terminal swelling rate of 1%/dpa. Furthermore, an ultrafine grain variant of this steel produced by severely plastic deformation exhibits a similar suppression of void nucleation in the injected interstitial region, but also shows a significantly extended transient regime, not reaching the terminal swelling rate by 60 dpa.« less

Influence of injected interstitials on the void swelling in two structural variants of 304L stainless steel induced by self-ion irradiation at 500 °C

DOE PAGES

Sun, C.; Garner, F. A.; Shao, L.; ...

2017-03-28

The two variants of AISI 304L stainless steel (SS) with different grain size distributions were ion irradiated at 500 °C to a peak dose of ~60 dpa. In the coarse-grained annealed variant, a peak swelling of ~12% was observed closer to the specimen surface rather than at the depth of peak displacement damage. The forward shift in depth between peak swelling and peak dose is proposed to be a consequence of suppression of void nucleation by injected interstitials. The swelling behavior in the front portion of the ion range mirrors that of neutron-induced swelling in this steel, exhibiting significant curvaturemore » with increasing dose as the swelling rate approaches the terminal swelling rate of 1%/dpa. Furthermore, an ultrafine grain variant of this steel produced by severely plastic deformation exhibits a similar suppression of void nucleation in the injected interstitial region, but also shows a significantly extended transient regime, not reaching the terminal swelling rate by 60 dpa.« less

Shifting the focus toward rare variants in schizophrenia to close the gap from genotype to phenotype.

PubMed

Bustamante, M Leonor; Herrera, Luisa; Gaspar, Pablo A; Nieto, Rodrigo; Maturana, Alejandro; Villar, María José; Salinas, Valeria; Silva, Hernán

2017-10-01

Schizophrenia (SZ) is a disorder with a high heritability and a complex architecture. Several dozen genetic variants have been identified as risk factors through genome-wide association studies including large population-based samples. However, the bulk of the risk cannot be accounted for by the genes associated to date. Rare mutations have been historically seen as relevant only for some infrequent, Mendelian forms of psychosis. Recent findings, however, show that the subset of patients that present a mutation with major effect is larger than expected. We discuss some of the molecular findings of these studies. SZ is clinically and genetically heterogeneous. To identify the genetic variation underlying the disorder, research should be focused on features that are more likely a product of genetic heterogeneity. Based on the phenotypical correlations with rare variants, cognition emerges as a relevant domain to study. Cognitive disturbances could be useful in selecting cases that have a higher probability of carrying deleterious mutations, as well as on the correct ascertainment of sporadic cases for the identification of de novo variants. © 2017 Wiley Periodicals, Inc.

Preoperative brain shift: study of three surgical cases

NASA Astrophysics Data System (ADS)

El Ganaoui, O.; Morandi, X.; Duchesne, S.; Jannin, P.

2008-03-01

In successful brain tumor surgery, the neurosurgeon's objectives are threefold: (1) reach the target, (2) remove it and (3) preserve eloquent tissue surrounding it. Surgical Planning (SP) consists in identifying optimal access route(s) to the target based on anatomical references and constrained by functional areas. Preoperative images are essential input in Multi-modal Image Guided NeuroSurgery systems (MIGNS) and update of these images, with precision and accuracy, is crucial to approach the anatomical reality in the Operating Room (OR). Intraoperative brain deformation has been previously identified by many research groups and related update of preoperative images has also been studied. We present a study of three surgical cases with tumors accompanied with edema and where corticosteroids were administered and monitored during a preoperative stage [t 0, t I = t 0 + 10 days]. In each case we observed a significant change in the Region Of Interest (ROI) and in anatomical references around it. This preoperative brain shift could induce error for localization during intervention (time t S) if the SP is based on the t 0 preoperative images. We computed volume variation, distance maps based on closest point (CP) for different components of the ROI, and displacement of center of mass (CM) of the ROI. The matching between sets of homologous landmarks from t 0 to t I was performed by an expert. The estimation of the landmarks displacement showed significant deformations around the ROI (landmarks shifted with mean of 3.90 +/- 0.92 mm and maximum of 5.45 mm for one case resection). The CM of the ROI moved about 6.92 mm for one biopsy. Accordingly, there was a sizable difference between SP based at t 0 vs SP based at t I, up to 7.95 mm for localization of reference access in one resection case. When compared to the typical MIGNS system accuracy (2 mm), it is recommended that preoperative images be updated within the interval time [t I,t S] in order to minimize the error correspondence between the anatomical reality and the preoperative data. This should help maximize the accuracy of registration between the preoperative images and the patient in the OR.

Functional Validation and Comparison Framework for EIT Lung Imaging

PubMed Central

Meybohm, Patrick; Weiler, Norbert; Frerichs, Inéz; Adler, Andy

2014-01-01

Introduction Electrical impedance tomography (EIT) is an emerging clinical tool for monitoring ventilation distribution in mechanically ventilated patients, for which many image reconstruction algorithms have been suggested. We propose an experimental framework to assess such algorithms with respect to their ability to correctly represent well-defined physiological changes. We defined a set of clinically relevant ventilation conditions and induced them experimentally in 8 pigs by controlling three ventilator settings (tidal volume, positive end-expiratory pressure and the fraction of inspired oxygen). In this way, large and discrete shifts in global and regional lung air content were elicited. Methods We use the framework to compare twelve 2D EIT reconstruction algorithms, including backprojection (the original and still most frequently used algorithm), GREIT (a more recent consensus algorithm for lung imaging), truncated singular value decomposition (TSVD), several variants of the one-step Gauss-Newton approach and two iterative algorithms. We consider the effects of using a 3D finite element model, assuming non-uniform background conductivity, noise modeling, reconstructing for electrode movement, total variation (TV) reconstruction, robust error norms, smoothing priors, and using difference vs. normalized difference data. Results and Conclusions Our results indicate that, while variation in appearance of images reconstructed from the same data is not negligible, clinically relevant parameters do not vary considerably among the advanced algorithms. Among the analysed algorithms, several advanced algorithms perform well, while some others are significantly worse. Given its vintage and ad-hoc formulation backprojection works surprisingly well, supporting the validity of previous studies in lung EIT. PMID:25110887

Digital tomosynthesis mammography: intra- and interplane artifact reduction for high-contrast objects on reconstructed slices using a priori 3D geometrical information

NASA Astrophysics Data System (ADS)

Ge, Jun; Chan, Heang-Ping; Sahiner, Berkman; Zhang, Yiheng; Wei, Jun; Hadjiiski, Lubomir M.; Zhou, Chuan

2007-03-01

We are developing a computerized technique to reduce intra- and interplane ghosting artifacts caused by high-contrast objects such as dense microcalcifications (MCs) or metal markers on the reconstructed slices of digital tomosynthesis mammography (DTM). In this study, we designed a constrained iterative artifact reduction method based on a priori 3D information of individual MCs. We first segmented individual MCs on projection views (PVs) using an automated MC detection system. The centroid and the contrast profile of the individual MCs in the 3D breast volume were estimated from the backprojection of the segmented individual MCs on high-resolution (0.1 mm isotropic voxel size) reconstructed DTM slices. An isolated volume of interest (VOI) containing one or a few MCs is then modeled as a high-contrast object embedded in a local homogeneous background. A shift-variant 3D impulse response matrix (IRM) of the projection-reconstruction (PR) system for the extracted VOI was calculated using the DTM geometry and the reconstruction algorithm. The PR system for this VOI is characterized by a system of linear equations. A constrained iterative method was used to solve these equations for the effective linear attenuation coefficients (eLACs) within the isolated VOI. Spatial constraint and positivity constraint were used in this method. Finally, the intra- and interplane artifacts on the whole breast volume resulting from the MC were calculated using the corresponding impulse responses and subsequently subtracted from the original reconstructed slices. The performance of our artifact-reduction method was evaluated using a computer-simulated MC phantom, as well as phantom images and patient DTMs obtained with IRB approval. A GE prototype DTM system that acquires 21 PVs in 3º increments over a +/-30º range was used for image acquisition in this study. For the computer-simulated MC phantom, the eLACs can be estimated accurately, thus the interplane artifacts were effectively removed. For MCs in phantom and patient DTMs, our method reduced the artifacts but also created small over-corrected areas in some cases. Potential reasons for this may include: the simplified mathematical modeling of the forward projection process, and the amplified noise in the solution of the system of linear equations.

WE-DE-BRA-01: SCIENCE COUNCIL JUNIOR INVESTIGATOR COMPETITION WINNER: Acceleration of a Limited-Angle Intrafraction Verification (LIVE) System Using Adaptive Prior Knowledge Based Image Estimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Y; Yin, F; Ren, L

Purpose: To develop an adaptive prior knowledge based image estimation method to reduce the scan angle needed in the LIVE system to reconstruct 4D-CBCT for intrafraction verification. Methods: The LIVE system has been previously proposed to reconstructs 4D volumetric images on-the-fly during arc treatment for intrafraction target verification and dose calculation. This system uses limited-angle beam’s eye view (BEV) MV cine images acquired from the treatment beam together with the orthogonally acquired limited-angle kV projections to reconstruct 4D-CBCT images for target verification during treatment. In this study, we developed an adaptive constrained free-form deformation reconstruction technique in LIVE to furthermore » reduce the scanning angle needed to reconstruct the CBCT images. This technique uses free form deformation with energy minimization to deform prior images to estimate 4D-CBCT based on projections acquired in limited angle (orthogonal 6°) during the treatment. Note that the prior images are adaptively updated using the latest CBCT images reconstructed by LIVE during treatment to utilize the continuity of patient motion.The 4D digital extended-cardiac-torso (XCAT) phantom was used to evaluate the efficacy of this technique with LIVE system. A lung patient was simulated with different scenario, including baseline drifts, amplitude change and phase shift. Limited-angle orthogonal kV and beam’s eye view (BEV) MV projections were generated for each scenario. The CBCT reconstructed by these projections were compared with the ground-truth generated in XCAT.Volume-percentage-difference (VPD) and center-of-mass-shift (COMS) were calculated between the reconstructed and the ground-truth tumors to evaluate the reconstruction accuracy. Results: Using orthogonal-view of 6° kV and BEV- MV projections, the VPD/COMS values were 12.7±4.0%/0.7±0.5 mm, 13.0±5.1%/0.8±0.5 mm, and 11.4±5.4%/0.5±0.3 mm for the three scenarios, respectively. Conclusion: The technique enables LIVE to accurately reconstruct 4D-CBCT images using only orthogonal 6° angle, which greatly improves the efficiency and reduces dose of LIVE for intrafraction verification.« less

SU-F-J-206: Systematic Evaluation of the Minimum Detectable Shift Using a Range- Finding Camera

DOE Office of Scientific and Technical Information (OSTI.GOV)

Platt, M; Platt, M; Lamba, M

2016-06-15

Purpose: The robotic table used for patient alignment in proton therapy is calibrated only at commissioning under well-defined conditions and table shifts may vary over time and with differing conditions. The purpose of this study is to systematically investigate minimum detectable shifts using a time-of-flight (TOF) range-finding camera for table position feedback. Methods: A TOF camera was used to acquire one hundred 424 × 512 range images from a flat surface before and after known shifts. Range was assigned by averaging central regions of the image across multiple images. Depth resolution was determined by evaluating the difference between the actualmore » shift of the surface and the measured shift. Depth resolution was evaluated for number of images averaged, area of sensor over which depth was averaged, distance from camera to surface, central versus peripheral image regions, and angle of surface relative to camera. Results: For one to one thousand images with a shift of one millimeter the range in error was 0.852 ± 0.27 mm to 0.004 ± 0.01 mm (95% C.I.). For varying regions of the camera sensor the range in error was 0.02 ± 0.05 mm to 0.47 ± 0.04 mm. The following results are for 10 image averages. For areas ranging from one pixel to 9 × 9 pixels the range in error was 0.15 ± 0.09 to 0.29 ± 0.15 mm (1σ). For distances ranging from two to four meters the range in error was 0.15 ± 0.09 to 0.28 ± 0.15 mm. For an angle of incidence between thirty degrees and ninety degrees the average range in error was 0.11 ± 0.08 to 0.17 ± 0.09 mm. Conclusion: It is feasible to use a TOF camera for measuring shifts in flat surfaces under clinically relevant conditions with submillimeter precision.« less

Multilevel Space-Time Aggregation for Bright Field Cell Microscopy Segmentation and Tracking

PubMed Central

Inglis, Tiffany; De Sterck, Hans; Sanders, Geoffrey; Djambazian, Haig; Sladek, Robert; Sundararajan, Saravanan; Hudson, Thomas J.

2010-01-01

A multilevel aggregation method is applied to the problem of segmenting live cell bright field microscope images. The method employed is a variant of the so-called “Segmentation by Weighted Aggregation” technique, which itself is based on Algebraic Multigrid methods. The variant of the method used is described in detail, and it is explained how it is tailored to the application at hand. In particular, a new scale-invariant “saliency measure” is proposed for deciding when aggregates of pixels constitute salient segments that should not be grouped further. It is shown how segmentation based on multilevel intensity similarity alone does not lead to satisfactory results for bright field cells. However, the addition of multilevel intensity variance (as a measure of texture) to the feature vector of each aggregate leads to correct cell segmentation. Preliminary results are presented for applying the multilevel aggregation algorithm in space time to temporal sequences of microscope images, with the goal of obtaining space-time segments (“object tunnels”) that track individual cells. The advantages and drawbacks of the space-time aggregation approach for segmentation and tracking of live cells in sequences of bright field microscope images are presented, along with a discussion on how this approach may be used in the future work as a building block in a complete and robust segmentation and tracking system. PMID:20467468

Normal magnetic resonance imaging anatomy of the ankle & foot.

PubMed

Arnold, George; Vohra, Saifuddin; Marcantonio, David; Doshi, Shashin

2011-08-01

This article discusses anatomic relationships, anatomic variants, and MRI protocols that pertain to the foot and ankle. MR images with detailed anatomic description form the cornerstone of this article. The superb image quality will facilitate learning normal imaging anatomy, as well as conceptualizing spatial relationships of anatomic structures. Copyright © 2011 Elsevier Inc. All rights reserved.

SU-E-J-237: Image Feature Based DRR and Portal Image Registration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, X; Chang, J

Purpose: Two-dimensional (2D) matching of the kV X-ray and digitally reconstructed radiography (DRR) images is an important setup technique for image-guided radiotherapy (IGRT). In our clinics, mutual information based methods are used for this purpose on commercial linear accelerators, but with often needs for manual corrections. This work proved the feasibility that feature based image transform can be used to register kV and DRR images. Methods: The scale invariant feature transform (SIFT) method was implemented to detect the matching image details (or key points) between the kV and DRR images. These key points represent high image intensity gradients, and thusmore » the scale invariant features. Due to the poor image contrast from our kV image, direct application of the SIFT method yielded many detection errors. To assist the finding of key points, the center coordinates of the kV and DRR images were read from the DICOM header, and the two groups of key points with similar relative positions to their corresponding centers were paired up. Using these points, a rigid transform (with scaling, horizontal and vertical shifts) was estimated. We also artificially introduced vertical and horizontal shifts to test the accuracy of our registration method on anterior-posterior (AP) and lateral pelvic images. Results: The results provided a satisfactory overlay of the transformed kV onto the DRR image. The introduced vs. detected shifts were fit into a linear regression. In the AP image experiments, linear regression analysis showed a slope of 1.15 and 0.98 with an R2 of 0.89 and 0.99 for the horizontal and vertical shifts, respectively. The results are 1.2 and 1.3 with R2 of 0.72 and 0.82 for the lateral image shifts. Conclusion: This work provided an alternative technique for kV to DRR alignment. Further improvements in the estimation accuracy and image contrast tolerance are underway.« less

Image encryption algorithm based on multiple mixed hash functions and cyclic shift

NASA Astrophysics Data System (ADS)

Wang, Xingyuan; Zhu, Xiaoqiang; Wu, Xiangjun; Zhang, Yingqian

2018-08-01

This paper proposes a new one-time pad scheme for chaotic image encryption that is based on the multiple mixed hash functions and the cyclic-shift function. The initial value is generated using both information of the plaintext image and the chaotic sequences, which are calculated from the SHA1 and MD5 hash algorithms. The scrambling sequences are generated by the nonlinear equations and logistic map. This paper aims to improve the deficiencies of traditional Baptista algorithms and its improved algorithms. We employ the cyclic-shift function and piece-wise linear chaotic maps (PWLCM), which give each shift number the characteristics of chaos, to diffuse the image. Experimental results and security analysis show that the new scheme has better security and can resist common attacks.

Directed molecular evolution to design advanced red fluorescent proteins.

PubMed

Subach, Fedor V; Piatkevich, Kiryl D; Verkhusha, Vladislav V

2011-11-29

Fluorescent proteins have become indispensable imaging tools for biomedical research. Continuing progress in fluorescence imaging, however, requires probes with additional colors and properties optimized for emerging techniques. Here we summarize strategies for development of red-shifted fluorescent proteins. We discuss possibilities for knowledge-based rational design based on the photochemistry of fluorescent proteins and the position of the chromophore in protein structure. We consider advances in library design by mutagenesis, protein expression systems and instrumentation for high-throughput screening that should yield improved fluorescent proteins for advanced imaging applications.

Point spread function engineering for iris recognition system design.

PubMed

Ashok, Amit; Neifeld, Mark A

2010-04-01

Undersampling in the detector array degrades the performance of iris-recognition imaging systems. We find that an undersampling of 8 x 8 reduces the iris-recognition performance by nearly a factor of 4 (on CASIA iris database), as measured by the false rejection ratio (FRR) metric. We employ optical point spread function (PSF) engineering via a Zernike phase mask in conjunction with multiple subpixel shifted image measurements (frames) to mitigate the effect of undersampling. A task-specific optimization framework is used to engineer the optical PSF and optimize the postprocessing parameters to minimize the FRR. The optimized Zernike phase enhanced lens (ZPEL) imager design with one frame yields an improvement of nearly 33% relative to a thin observation module by bounded optics (TOMBO) imager with one frame. With four frames the optimized ZPEL imager achieves a FRR equal to that of the conventional imager without undersampling. Further, the ZPEL imager design using 16 frames yields a FRR that is actually 15% lower than that obtained with the conventional imager without undersampling.

Two photon spectroscopy and microscopy of the fluorescent flavoprotein, iLOV.

PubMed

Homans, Rachael J; Khan, Raja U; Andrews, Michael B; Kjeldsen, Annemette E; Natrajan, Louise S; Marsden, Steven; McKenzie, Edward A; Christie, John M; Jones, Alex R

2018-06-06

LOV-domains are ubiquitous photosensory proteins that are commonly re-engineered to serve as powerful and versatile fluorescent proteins and optogenetic tools. The photoactive, flavin chromophore, however, is excited using short wavelengths of light in the blue and UV regions, which have limited penetration into biological samples and can cause photodamage. Here, we have used non-linear spectroscopy and microscopy of the fluorescent protein, iLOV, to reveal that functional variants of LOV can be activated to great effect by two non-resonant photons of lower energy, near infrared light, not only in solution but also in biological samples. The two photon cross section of iLOV has a significantly blue-shifted S0 → S1 transition compared with the one photon absorption spectrum, suggesting preferential population of excited vibronic states. It is highly likely, therefore, that the two photon absorption wavelength of engineered, LOV-based tools is tuneable. We also demonstrate for the first time two photon imaging using iLOV in human epithelial kidney cells. Consequently, two photon absorption by engineered, flavin-based bio-molecular tools can enable non-invasive activation with high depth resolution and the potential for not only improved image clarity but also enhanced spatiotemporal control for optogenetic applications.

Applications of Space-Time Duality

NASA Astrophysics Data System (ADS)

Plansinis, Brent W.

The concept of space-time duality is based on a mathematical analogy between paraxial diffraction and narrowband dispersion, and has led to the development of temporal imaging systems. The first part of this thesis focuses on the development of a temporal imaging system for the Laboratory for Laser Energetics. Using an electro-optic phase modulator as a time lens, a time-to-frequency converter is constructed capable of imaging pulses between 3 and 12 ps. Numerical simulations show how this system can be improved to image the 1-30 ps range used in OMEGA-EP. By adjusting the timing between the pulse and the sinusoidal clock of the phase modulator, the pulse spectrum can be selectively narrowed, broadened, or shifted. An experimental demonstration of this effect achieved spectral narrowing and broadening by a factor of 2. Numerical simulations show narrowing by a factor of 8 is possible with modern phase modulators. The second part of this thesis explores the space-time analog of reflection and refraction from a moving refractive index boundary. From a physics perspective, a temporal boundary breaks translational symmetry in time, requiring the momentum of the photon to remain unchanged while its energy may change. This leads to a shifting and splitting of the pulse spectrum as the boundary is crossed. Equations for the reflected and transmitted frequencies and a condition for total internal reflection are found. Two of these boundaries form a temporal waveguide, which confines the pulse to a narrow temporal window. These waveguides have a finite number of modes, which do not change during propagation. A single-mode waveguide can be created, allowing only a single pulse shape to form within the waveguide. Temporal reflection and refraction produce a frequency dependent phase shift on the incident pulse, leading to interference fringes between the incident light and the reflected light. In a waveguide, this leads to self-imaging, where the pulse shape reforms periodically at finite propagation lengths. Numerical simulations are performed for the specific case where the moving boundary is produced through cross-phase modulation. In this case, the Kerr nonlinearity causes the boundary to change during propagation, leading to unique temporal and spectral behavior.

Performance analysis of algorithms for retrieval of magnetic resonance images for interactive teleradiology

NASA Astrophysics Data System (ADS)

Atkins, M. Stella; Hwang, Robert; Tang, Simon

2001-05-01

We have implemented a prototype system consisting of a Java- based image viewer and a web server extension component for transmitting Magnetic Resonance Images (MRI) to an image viewer, to test the performance of different image retrieval techniques. We used full-resolution images, and images compressed/decompressed using the Set Partitioning in Hierarchical Trees (SPIHT) image compression algorithm. We examined the SPIHT decompression algorithm using both non- progressive and progressive transmission, focusing on the running times of the algorithm, client memory usage and garbage collection. We also compared the Java implementation with a native C++ implementation of the non- progressive SPIHT decompression variant. Our performance measurements showed that for uncompressed image retrieval using a 10Mbps Ethernet, a film of 16 MR images can be retrieved and displayed almost within interactive times. The native C++ code implementation of the client-side decoder is twice as fast as the Java decoder. If the network bandwidth is low, the high communication time for retrieving uncompressed images may be reduced by use of SPIHT-compressed images, although the image quality is then degraded. To provide diagnostic quality images, we also investigated the retrieval of up to 3 images on a MR film at full-resolution, using progressive SPIHT decompression. The Java-based implementation of progressive decompression performed badly, mainly due to the memory requirements for maintaining the image states, and the high cost of execution of the Java garbage collector. Hence, in systems where the bandwidth is high, such as found in a hospital intranet, SPIHT image compression does not provide advantages for image retrieval performance.

Programmable remapper for image processing

NASA Technical Reports Server (NTRS)

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

1991-01-01

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.

Morphological variants of Moniliophthora roreri on artificial media and the biotroph/necrotroph shift

USDA-ARS?s Scientific Manuscript database

Moniliophthora roreri is an unusual fungus and plant pathogen on many levels. Although M. roreri is an aggressive pathogen of cacao (Theobroma cacao), many species grouped in the genus Moniliophthora are considered endophytes. The morphology of M. roreri is confusing and for many years it was consid...

A novel method for real-time edge-enhancement and its application to pattern recognition

NASA Astrophysics Data System (ADS)

Ge, Huayong; Bai, Enjian; Fan, Hong

2010-11-01

The coupling gain coefficient g is redefined and deduced based on coupling theory, the variant of coupling gain coefficient g for different ΓL and r is analyzed. A new optical system is proposed for image edge-enhancement. It recycles the back signal to amplify the edge signal, which has the advantages of high throughput efficiency and brightness. The optical system is designed and built, and the edge-enhanced image of hand bone is captured electronically by CCD camera. The principle of optical correlation is demonstrated, 3-D correlation distribution of letter H with and without edge-enhancement is simulated, the discrimination capability Iac and the full-width at half maximum intensity (FWHM) are compared for two kinds of correlators. The analysis shows that edge-enhancement preprocessing can improve the performance of correlator effectively.

Alignment by Maximization of Mutual Information

DTIC Science & Technology

1995-06-01

Davi Geiger, David Chapman, Jose Robles, Tao Alter, Misha Bolotski, Jonathan Connel, Karen Sarachik, Maja Mataric , Ian Horswill, Colin Angle...the same pose. These images are very different and are in fact anti-correlated: bright pixels in the left image correspond to dark pixels in the right...image; dark pixels in the left image correspond to bright pixels in the right image. No variant of correlation could match these images together

GM1 gangliosidosis in a Japanese domestic cat: a new variant identified in Hokkaido, Japan

PubMed Central

UENO, Hiroshi; YAMATO, Osamu; SUGIURA, Takeshi; KOHYAMA, Moeko; YABUKI, Akira; MIYOSHI, Kenjiro; MATSUDA, Kazuya; UCHIDE, Tsuyoshi

2015-01-01

A male Japanese domestic cat with retarded growth in Hokkaido, Japan, showed progressive motor dysfunction, such as ataxia starting at 3 months of age and tremors, visual disorder and seizure after 4 months of age. Finally, the cat died of neurological deterioration at 9 months of age. Approximately half of the peripheral blood lymphocytes had multiple abnormal vacuoles. Magnetic resonance imaging showed bisymmetrical hyperintensity in the white matter of the parietal and occipital lobes in the forebrain on T2-weighted and fluid-attenuated inversion recovery images, and mild encephalatrophy of the olfactory bulbs and temporal lobes. The activity of lysosomal acid β-galactosidase in leukocytes was negligible, resulting in the biochemical diagnosis of GM1 gangliosidosis. Histologically, swollen neurons characterized by accumulation of pale, slightly granular cytoplasmic materials were observed throughout the central nervous system. Dysmyelination or demyelination and gemistocytic astrocytosis were observed in the white matter. Ultrastructually, membranous cytoplasmic bodies were detected in the lysosomes of neurons. However, genetic analysis did not identify the c.1448G>C mutation, which is the single known mutation of feline GM1 gangliosidosis, suggesting that the cat was affected with a new variant of the feline disease. PMID:26234889

Holographic motion picture camera with Doppler shift compensation

NASA Technical Reports Server (NTRS)

Kurtz, R. L. (Inventor)

1976-01-01

A holographic motion picture camera is reported for producing three dimensional images by employing an elliptical optical system. There is provided in one of the beam paths (the object or reference beam path) a motion compensator which enables the camera to photograph faster moving objects.

Whole-exome sequencing of a rare case of familial childhood acute lymphoblastic leukemia reveals putative predisposing mutations in Fanconi anemia genes.

PubMed

Spinella, Jean-François; Healy, Jasmine; Saillour, Virginie; Richer, Chantal; Cassart, Pauline; Ouimet, Manon; Sinnett, Daniel

2015-07-23

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer. While the multi-step model of pediatric leukemogenesis suggests interplay between constitutional and somatic genomes, the role of inherited genetic variability remains largely undescribed. Nonsyndromic familial ALL, although extremely rare, provides the ideal setting to study inherited contributions to ALL. Toward this goal, we sequenced the exomes of a childhood ALL family consisting of mother, father and two non-twinned siblings diagnosed with concordant pre-B hyperdiploid ALL and previously shown to have inherited a rare form of PRDM9, a histone H3 methyltransferase involved in crossing-over at recombination hotspots and Holliday junctions. We postulated that inheritance of additional rare disadvantaging variants in predisposing cancer genes could affect genomic stability and lead to increased risk of hyperdiploid ALL within this family. Whole exomes were captured using Agilent's SureSelect kit and sequenced on the Life Technologies SOLiD System. We applied a data reduction strategy to identify candidate variants shared by both affected siblings. Under a recessive disease model, we focused on rare non-synonymous or frame-shift variants in leukemia predisposing pathways. Though the family was nonsyndromic, we identified a combination of rare variants in Fanconi anemia (FA) genes FANCP/SLX4 (compound heterozygote - rs137976282/rs79842542) and FANCA (rs61753269) and a rare homozygous variant in the Holliday junction resolvase GEN1 (rs16981869). These variants, predicted to affect protein function, were previously identified in familial breast cancer cases. Based on our in-house database of 369 childhood ALL exomes, the sibs were the only patients to carry this particularly rare combination and only a single hyperdiploid patient was heterozygote at both FANCP/SLX4 positions, while no FANCA variant allele carriers were identified. FANCA is the most commonly mutated gene in FA and is essential for resolving DNA interstrand cross-links during replication. FANCP/SLX4 and GEN1 are involved in the cleavage of Holliday junctions and their mutated forms, in combination with the rare allele of PRDM9, could alter Holliday junction resolution leading to nondisjunction of chromosomes and segregation defects. Taken together, these results suggest that concomitant inheritance of rare variants in FANCA, FANCP/SLX4 and GEN1 on the specific genetic background of this familial case, could lead to increased genomic instability, hematopoietic dysfunction, and higher risk of childhood leukemia.

NASA Tech Briefs, March 2008

NASA Technical Reports Server (NTRS)

2008-01-01

Topics covered include: WRATS Integrated Data Acquisition System; Breadboard Signal Processor for Arraying DSN Antennas; Digital Receiver Phase Meter; Split-Block Waveguide Polarization Twist for 220 to 325 GHz; Nano-Multiplication-Region Avalanche Photodiodes and Arrays; Tailored Asymmetry for Enhanced Coupling to WGM Resonators; Disabling CNT Electronic Devices by Use of Electron Beams; Conical Bearingless Motor/Generators; Integrated Force Method for Indeterminate Structures; Carbon-Nanotube-Based Electrodes for Biomedical Applications; Compact Directional Microwave Antenna for Localized Heating; Using Hyperspectral Imagery to Identify Turfgrass Stresses; Shaping Diffraction-Grating Grooves to Optimize Efficiency; Low-Light-Shift Cesium Fountain without Mechanical Shutters; Magnetic Compensation for Second-Order Doppler Shift in LITS; Nanostructures Exploit Hybrid-Polariton Resonances; Microfluidics, Chromatography, and Atomic-Force Microscopy; Model of Image Artifacts from Dust Particles; Pattern-Recognition System for Approaching a Known Target; Orchestrator Telemetry Processing Pipeline; Scheme for Quantum Computing Immune to Decoherence; Spin-Stabilized Microsatellites with Solar Concentrators; Phase Calibration of Antenna Arrays Aimed at Spacecraft; Ring Bus Architecture for a Solid-State Recorder; and Image Compression Algorithm Altered to Improve Stereo Ranging.

Differential regulation of metabolic pathways by androgen receptor (AR) and its constitutively active splice variant, AR-V7, in prostate cancer cells

PubMed Central

Shafi, Ayesha A.; Putluri, Vasanta; Arnold, James M.; Tsouko, Efrosini; Maity, Suman; Roberts, Justin M.; Coarfa, Cristian; Frigo, Daniel E.; Putluri, Nagireddy; Sreekumar, Arun; Weigel, Nancy L.

2015-01-01

Metastatic prostate cancer (PCa) is primarily an androgen-dependent disease, which is treated with androgen deprivation therapy (ADT). Tumors usually develop resistance (castration-resistant PCa [CRPC]), but remain androgen receptor (AR) dependent. Numerous mechanisms for AR-dependent resistance have been identified including expression of constitutively active AR splice variants lacking the hormone-binding domain. Recent clinical studies show that expression of the best-characterized AR variant, AR-V7, correlates with resistance to ADT and poor outcome. Whether AR-V7 is simply a constitutively active substitute for AR or has novel gene targets that cause unique downstream changes is unresolved. Several studies have shown that AR activation alters cell metabolism. Using LNCaP cells with inducible expression of AR-V7 as a model system, we found that AR-V7 stimulated growth, migration, and glycolysis measured by ECAR (extracellular acidification rate) similar to AR. However, further analyses using metabolomics and metabolic flux assays revealed several differences. Whereas AR increased citrate levels, AR-V7 reduced citrate mirroring metabolic shifts observed in CRPC patients. Flux analyses indicate that the low citrate is a result of enhanced utilization rather than a failure to synthesize citrate. Moreover, flux assays suggested that compared to AR, AR-V7 exhibits increased dependence on glutaminolysis and reductive carboxylation to produce some of the TCA (tricarboxylic acid cycle) metabolites. These findings suggest that these unique actions represent potential therapeutic targets. PMID:26378018

Comparative Analysis of the Flax Immune Receptors L6 and L7 Suggests an Equilibrium-Based Switch Activation Model

PubMed Central

Chen, Chunhong; Newell, Kim; Lawrence, Gregory J.; Ellis, Jeffrey G.; Anderson, Peter A.; Dodds, Peter N.

2016-01-01

NOD-like receptors (NLRs) are central components of the plant immune system. L6 is a Toll/interleukin-1 receptor (TIR) domain-containing NLR from flax (Linum usitatissimum) conferring immunity to the flax rust fungus. Comparison of L6 to the weaker allele L7 identified two polymorphic regions in the TIR and the nucleotide binding (NB) domains that regulate both effector ligand-dependent and -independent cell death signaling as well as nucleotide binding to the receptor. This suggests that a negative functional interaction between the TIR and NB domains holds L7 in an inactive/ADP-bound state more tightly than L6, hence decreasing its capacity to adopt the active/ATP-bound state and explaining its weaker activity in planta. L6 and L7 variants with a more stable ADP-bound state failed to bind to AvrL567 in yeast two-hybrid assays, while binding was detected to the signaling active variants. This contrasts with current models predicting that effectors bind to inactive receptors to trigger activation. Based on the correlation between nucleotide binding, effector interaction, and immune signaling properties of L6/L7 variants, we propose that NLRs exist in an equilibrium between ON and OFF states and that effector binding to the ON state stabilizes this conformation, thereby shifting the equilibrium toward the active form of the receptor to trigger defense signaling. PMID:26744216

New color-shifting security devices

NASA Astrophysics Data System (ADS)

Moia, Franco

2004-06-01

The unbroken global increase of forgery and counterfeiting of valuable documents and products steadily requires improved types of optical security devices. Hence, the "security world" is actively seeking for new features which meet high security standards, look attractively and allow easy recognition. One special smart security device created by ROLIC's technology represents a cholesteric device combined with a phase image. On tilting, such devices reveal strong color shifts which are clearly visible to the naked eye. The additional latent image is invisible under normal lighting conditions but can be revealed to human eyes by means of a simple, commercially available linear sheet polarizer. Based on our earlier work, first published in 1981, we now have developed phase change guest-host devices combined with dye-doped cholesteric material for application in new security features. ROLIC has developed sophisticated material systems of cross-linkable cholesteric liquid crystals and suitable cross-linkable dyes which allow to create outstanding cholesteric color-shifting effects not only on light absorbing dark backgrounds but also on bright or even white backgrounds preserving the circularly polarizing state. The new security devices combine unambiguously 1st and 2nd level inspection features and show brilliant colors on black as well as on white substrates. On tilting, the security devices exhibit remarkable color shifts while the integrated hidden images can be revealed by use of a sheet polarizer. Furthermore, due to its very thin material layers, even demanding applications, such as on banknotes can be considered.

Content standards for medical image metadata

NASA Astrophysics Data System (ADS)

d'Ornellas, Marcos C.; da Rocha, Rafael P.

2003-12-01

Medical images are at the heart of the healthcare diagnostic procedures. They have provided not only a noninvasive mean to view anatomical cross-sections of internal organs but also a mean for physicians to evaluate the patient"s diagnosis and monitor the effects of the treatment. For a Medical Center, the emphasis may shift from the generation of image to post processing and data management since the medical staff may generate even more processed images and other data from the original image after various analyses and post processing. A medical image data repository for health care information system is becoming a critical need. This data repository would contain comprehensive patient records, including information such as clinical data and related diagnostic images, and post-processed images. Due to the large volume and complexity of the data as well as the diversified user access requirements, the implementation of the medical image archive system will be a complex and challenging task. This paper discusses content standards for medical image metadata. In addition it also focuses on the image metadata content evaluation and metadata quality management.

Behavioral and Neural Manifestations of Reward Memory in Carriers of Low-Expressing versus High-Expressing Genetic Variants of the Dopamine D2 Receptor

PubMed Central

Richter, Anni; Barman, Adriana; Wüstenberg, Torsten; Soch, Joram; Schanze, Denny; Deibele, Anna; Behnisch, Gusalija; Assmann, Anne; Klein, Marieke; Zenker, Martin; Seidenbecher, Constanze; Schott, Björn H.

2017-01-01

Dopamine is critically important in the neural manifestation of motivated behavior, and alterations in the human dopaminergic system have been implicated in the etiology of motivation-related psychiatric disorders, most prominently addiction. Patients with chronic addiction exhibit reduced dopamine D2 receptor (DRD2) availability in the striatum, and the DRD2 TaqIA (rs1800497) and C957T (rs6277) genetic polymorphisms have previously been linked to individual differences in striatal dopamine metabolism and clinical risk for alcohol and nicotine dependence. Here, we investigated the hypothesis that the variants of these polymorphisms would show increased reward-related memory formation, which has previously been shown to jointly engage the mesolimbic dopaminergic system and the hippocampus, as a potential intermediate phenotype for addiction memory. To this end, we performed functional magnetic resonance imaging (fMRI) in 62 young, healthy individuals genotyped for DRD2 TaqIA and C957T variants. Participants performed an incentive delay task, followed by a recognition memory task 24 h later. We observed effects of both genotypes on the overall recognition performance with carriers of low-expressing variants, namely TaqIA A1 carriers and C957T C homozygotes, showing better performance than the other genotype groups. In addition to the better memory performance, C957T C homozygotes also exhibited a response bias for cues predicting monetary reward. At the neural level, the C957T polymorphism was associated with a genotype-related modulation of right hippocampal and striatal fMRI responses predictive of subsequent recognition confidence for reward-predicting items. Our results indicate that genetic variations associated with DRD2 expression affect explicit memory, specifically for rewarded stimuli. We suggest that the relatively better memory for rewarded stimuli in carriers of low-expressing DRD2 variants may reflect an intermediate phenotype of addiction memory. PMID:28507526

A Novel Genome-Information Content-Based Statistic for Genome-Wide Association Analysis Designed for Next-Generation Sequencing Data

PubMed Central

Luo, Li; Zhu, Yun

2012-01-01

Abstract The genome-wide association studies (GWAS) designed for next-generation sequencing data involve testing association of genomic variants, including common, low frequency, and rare variants. The current strategies for association studies are well developed for identifying association of common variants with the common diseases, but may be ill-suited when large amounts of allelic heterogeneity are present in sequence data. Recently, group tests that analyze their collective frequency differences between cases and controls shift the current variant-by-variant analysis paradigm for GWAS of common variants to the collective test of multiple variants in the association analysis of rare variants. However, group tests ignore differences in genetic effects among SNPs at different genomic locations. As an alternative to group tests, we developed a novel genome-information content-based statistics for testing association of the entire allele frequency spectrum of genomic variation with the diseases. To evaluate the performance of the proposed statistics, we use large-scale simulations based on whole genome low coverage pilot data in the 1000 Genomes Project to calculate the type 1 error rates and power of seven alternative statistics: a genome-information content-based statistic, the generalized T2, collapsing method, multivariate and collapsing (CMC) method, individual χ2 test, weighted-sum statistic, and variable threshold statistic. Finally, we apply the seven statistics to published resequencing dataset from ANGPTL3, ANGPTL4, ANGPTL5, and ANGPTL6 genes in the Dallas Heart Study. We report that the genome-information content-based statistic has significantly improved type 1 error rates and higher power than the other six statistics in both simulated and empirical datasets. PMID:22651812

A novel genome-information content-based statistic for genome-wide association analysis designed for next-generation sequencing data.

PubMed

Luo, Li; Zhu, Yun; Xiong, Momiao

2012-06-01

The genome-wide association studies (GWAS) designed for next-generation sequencing data involve testing association of genomic variants, including common, low frequency, and rare variants. The current strategies for association studies are well developed for identifying association of common variants with the common diseases, but may be ill-suited when large amounts of allelic heterogeneity are present in sequence data. Recently, group tests that analyze their collective frequency differences between cases and controls shift the current variant-by-variant analysis paradigm for GWAS of common variants to the collective test of multiple variants in the association analysis of rare variants. However, group tests ignore differences in genetic effects among SNPs at different genomic locations. As an alternative to group tests, we developed a novel genome-information content-based statistics for testing association of the entire allele frequency spectrum of genomic variation with the diseases. To evaluate the performance of the proposed statistics, we use large-scale simulations based on whole genome low coverage pilot data in the 1000 Genomes Project to calculate the type 1 error rates and power of seven alternative statistics: a genome-information content-based statistic, the generalized T(2), collapsing method, multivariate and collapsing (CMC) method, individual χ(2) test, weighted-sum statistic, and variable threshold statistic. Finally, we apply the seven statistics to published resequencing dataset from ANGPTL3, ANGPTL4, ANGPTL5, and ANGPTL6 genes in the Dallas Heart Study. We report that the genome-information content-based statistic has significantly improved type 1 error rates and higher power than the other six statistics in both simulated and empirical datasets.

Block randomization versus complete randomization of human perception stimuli: is there a difference?

NASA Astrophysics Data System (ADS)

Moyer, Steve; Uhl, Elizabeth R.

2015-05-01

For more than 50 years, the U.S. Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate (NVESD) has been studying and modeling the human visual discrimination process as it pertains to military imaging systems. In order to develop sensor performance models, human observers are trained to expert levels in the identification of military vehicles. From 1998 until 2006, the experimental stimuli were block randomized, meaning that stimuli with similar difficulty levels (for example, in terms of distance from target, blur, noise, etc.) were presented together in blocks of approximately 24 images but the order of images within the block was random. Starting in 2006, complete randomization came into vogue, meaning that difficulty could change image to image. It was thought that this would provide a more statistically robust result. In this study we investigated the impact of the two types of randomization on performance in two groups of observers matched for skill to create equivalent groups. It is hypothesized that Soldiers in the Complete Randomized condition will have to shift their decision criterion more frequently than Soldiers in the Block Randomization group and this shifting is expected to impede performance so that Soldiers in the Block Randomized group perform better.

The influence of a change in the meniscus cross-sectional shape on the medio-lateral translation of the knee joint and meniscal extrusion

PubMed Central

Daszkiewicz, Karol; Witkowski, Wojciech; Chróścielewski, Jacek; Ferenc, Tomasz; Baczkowski, Boguslaw

2018-01-01

Objective The purpose of this study was to evaluate the influence of a change in the meniscus cross sectional shape on its position and on the biomechanics of a knee joint. Methods One main finite element model of a left knee joint was created on the basis of MRI images. The model consisted of bones, articular cartilages, menisci and ligaments. Eight variants of this model with an increased or decreased meniscus height were then prepared. Nonlinear static analyses with a fixed flexion/extension movement for a compressive load of 1000 N were performed. The additional analyses for those models with a constrained medio-lateral relative bone translation allowed for an evaluation of the influence of this translation on a meniscus external shift. Results It was observed that a decrease in the meniscus height caused a decrease in the contact area, together with a decrease in the contact force between the flattened meniscus and the cartilage. For the models with an increased meniscus height, a maximal value of force acting on the meniscus in a medio-lateral direction was obtained. The results have shown that the meniscus external shift was approximately proportional to the meniscus slope angle, but that relationship was modified by a medio-lateral relative bone translation. It was found that the translation of the femur relative to the tibia may be dependent on the geometry of the menisci. Conclusions The results have suggested that a change in the meniscus geometry in the cross sectional plane can considerably affect not only the meniscal external shift, but also the medio-lateral translation of the knee joint as well as the congruency of the knee joint. PMID:29447236

The influence of a change in the meniscus cross-sectional shape on the medio-lateral translation of the knee joint and meniscal extrusion.

PubMed

Luczkiewicz, Piotr; Daszkiewicz, Karol; Witkowski, Wojciech; Chróścielewski, Jacek; Ferenc, Tomasz; Baczkowski, Boguslaw

2018-01-01

The purpose of this study was to evaluate the influence of a change in the meniscus cross sectional shape on its position and on the biomechanics of a knee joint. One main finite element model of a left knee joint was created on the basis of MRI images. The model consisted of bones, articular cartilages, menisci and ligaments. Eight variants of this model with an increased or decreased meniscus height were then prepared. Nonlinear static analyses with a fixed flexion/extension movement for a compressive load of 1000 N were performed. The additional analyses for those models with a constrained medio-lateral relative bone translation allowed for an evaluation of the influence of this translation on a meniscus external shift. It was observed that a decrease in the meniscus height caused a decrease in the contact area, together with a decrease in the contact force between the flattened meniscus and the cartilage. For the models with an increased meniscus height, a maximal value of force acting on the meniscus in a medio-lateral direction was obtained. The results have shown that the meniscus external shift was approximately proportional to the meniscus slope angle, but that relationship was modified by a medio-lateral relative bone translation. It was found that the translation of the femur relative to the tibia may be dependent on the geometry of the menisci. The results have suggested that a change in the meniscus geometry in the cross sectional plane can considerably affect not only the meniscal external shift, but also the medio-lateral translation of the knee joint as well as the congruency of the knee joint.

Matching Real and Synthetic Panoramic Images Using a Variant of Geometric Hashing

NASA Astrophysics Data System (ADS)

Li-Chee-Ming, J.; Armenakis, C.

2017-05-01

This work demonstrates an approach to automatically initialize a visual model-based tracker, and recover from lost tracking, without prior camera pose information. These approaches are commonly referred to as tracking-by-detection. Previous tracking-by-detection techniques used either fiducials (i.e. landmarks or markers) or the object's texture. The main contribution of this work is the development of a tracking-by-detection algorithm that is based solely on natural geometric features. A variant of geometric hashing, a model-to-image registration algorithm, is proposed that searches for a matching panoramic image from a database of synthetic panoramic images captured in a 3D virtual environment. The approach identifies corresponding features between the matched panoramic images. The corresponding features are to be used in a photogrammetric space resection to estimate the camera pose. The experiments apply this algorithm to initialize a model-based tracker in an indoor environment using the 3D CAD model of the building.

Optimization of compressive 4D-spatio-spectral snapshot imaging

NASA Astrophysics Data System (ADS)

Zhao, Xia; Feng, Weiyi; Lin, Lihua; Su, Wu; Xu, Guoqing

2017-10-01

In this paper, a modified 3D computational reconstruction method in the compressive 4D-spectro-volumetric snapshot imaging system is proposed for better sensing spectral information of 3D objects. In the design of the imaging system, a microlens array (MLA) is used to obtain a set of multi-view elemental images (EIs) of the 3D scenes. Then, these elemental images with one dimensional spectral information and different perspectives are captured by the coded aperture snapshot spectral imager (CASSI) which can sense the spectral data cube onto a compressive 2D measurement image. Finally, the depth images of 3D objects at arbitrary depths, like a focal stack, are computed by inversely mapping the elemental images according to geometrical optics. With the spectral estimation algorithm, the spectral information of 3D objects is also reconstructed. Using a shifted translation matrix, the contrast of the reconstruction result is further enhanced. Numerical simulation results verify the performance of the proposed method. The system can obtain both 3D spatial information and spectral data on 3D objects using only one single snapshot, which is valuable in the agricultural harvesting robots and other 3D dynamic scenes.

Atrophy and structural covariance of the cholinergic basal forebrain in primary progressive aphasia.

PubMed

Teipel, Stefan; Raiser, Theresa; Riedl, Lina; Riederer, Isabelle; Schroeter, Matthias L; Bisenius, Sandrine; Schneider, Anja; Kornhuber, Johannes; Fliessbach, Klaus; Spottke, Annika; Grothe, Michel J; Prudlo, Johannes; Kassubek, Jan; Ludolph, Albert; Landwehrmeyer, Bernhard; Straub, Sarah; Otto, Markus; Danek, Adrian

2016-10-01

Primary progressive aphasia (PPA) is characterized by profound destruction of cortical language areas. Anatomical studies suggest an involvement of cholinergic basal forebrain (BF) in PPA syndromes, particularly in the area of the nucleus subputaminalis (NSP). Here we aimed to determine the pattern of atrophy and structural covariance as a proxy of structural connectivity of BF nuclei in PPA variants. We studied 62 prospectively recruited cases with the clinical diagnosis of PPA and 31 healthy older control participants from the cohort study of the German consortium for frontotemporal lobar degeneration (FTLD). We determined cortical and BF atrophy based on high-resolution magnetic resonance imaging (MRI) scans. Patterns of structural covariance of BF with cortical regions were determined using voxel-based partial least square analysis. We found significant atrophy of total BF and BF subregions in PPA patients compared with controls [F(1, 82) = 20.2, p < .001]. Atrophy was most pronounced in the NSP and the posterior BF, and most severe in the semantic variant and the nonfluent variant of PPA. Structural covariance analysis in healthy controls revealed associations of the BF nuclei, particularly the NSP, with left hemispheric predominant prefrontal, lateral temporal, and parietal cortical areas, including Broca's speech area (p < .001, permutation test). In contrast, the PPA patients showed preserved structural covariance of the BF nuclei mostly with right but not with left hemispheric cortical areas (p < .001, permutation test). Our findings agree with the neuroanatomically proposed involvement of the cholinergic BF, particularly the NSP, in PPA syndromes. We found a shift from a structural covariance of the BF with left hemispheric cortical areas in healthy aging towards right hemispheric cortical areas in PPA, possibly reflecting a consequence of the profound and early destruction of cortical language areas in PPA. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

A Framework for Automated Digital Forensic Reporting

DTIC Science & Technology

2009-03-01

provide a simple way to extract local accounts from a full system image. Unix, Linux and the BSD variants store user accounts in the /etc/ passwd file...with hashes of the user passwords in the /etc/shadow file for linux or /etc/master.passwd for BSD. /etc/ passwd also contains mappings from usernames to... passwd file may not map directly to real-world names, it can be a crucial link in this eventual mapping. Following are two examples where it could prove

An NPC1L1 gene promoter variant is associated with autosomal dominant hypercholesterolemia.

PubMed

Martín, B; Solanas-Barca, M; García-Otín, A-L; Pampín, S; Cofán, M; Ros, E; Rodríguez-Rey, J-C; Pocoví, M; Civeira, F

2010-05-01

A substantial number of subjects with autosomal dominant hypercholesterolemia (ADH) do not have LDL receptor (LDLR) or apolipoprotein B (APOB) mutations. Some ADH subjects appear to hyperabsorb sterols from the intestine, thus we hypothesized that they could have variants of the Niemann-Pick C1-Like 1 gene (NPC1L1). NPC1L1 encodes a crucial protein involved in intestinal sterol absorption. Four NPC1L1 variants (-133A>G, -18C>A, 1679C>G, 28650A>G) were analyzed in 271 (155 women and 116 men) ADH bearers without mutations in LDLR or APOB aged 30-70years and 274 (180 women and 94 men) control subjects aged 25-65years. The AC haplotype determined by the -133A>G and -18C>A variants was underrepresented in ADH subjects compared to controls (p=0.01). In the ADH group, cholesterol absorption/synthesis markers were significantly lower in AC homozygotes that in all others haplotypes. Electrophoretic mobility shift assay (EMSA) results revealed that the -133A-specific oligonucleotide produced a retarded band stronger than the -133G allele. Luciferase activity with NPC1L1 -133G variant was 2.5-fold higher than with the -133A variant. The -133A>G polymorphism exerts a significant effect on NPC1L1 promoter activity. NPC1L1 promoter variants might explain in part the hypercholesterolemic phenotype of some subjects with nonLDLR/nonAPOB ADH. Copyright 2009 Elsevier B.V. All rights reserved.

Complexin2 modulates working memory-related neural activity in patients with schizophrenia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hass, Johanna; Walton, Esther; Kirsten, Holger

The specific contribution of risk or candidate gene variants to the complex phenotype of schizophrenia is largely unknown. Studying the effects of such variants on brain function can provide insight into disease-associated mechanisms on a neural systems level. Previous studies found common variants in the complexin2 ( CPLX2) gene to be highly associated with cognitive dysfunction in schizophrenia patients. Similarly, cognitive functioning was found to be impaired in Cplx2 gene-deficient mice if they were subjected to maternal deprivation or mild brain trauma during puberty. Here, we aimed to study seven common CPLX2 single-nucleotide polymorphisms (SNPs) and their neurogenetic risk mechanismsmore » by investigating their relationship to a schizophrenia-related functional neuroimaging intermediate phenotype. In this paper, we examined functional MRI and genotype data collected from 104 patients with DSM-IV-diagnosed schizophrenia and 122 healthy controls who participated in the Mind Clinical Imaging Consortium study of schizophrenia. Seven SNPs distributed over the whole CPLX2 gene were tested for association with working memory-elicited neural activity in a frontoparietal neural network. Three CPLX2 SNPs were significantly associated with increased neural activity in the dorsolateral prefrontal cortex and intraparietal sulcus in the schizophrenia sample, but showed no association in healthy controls. Finally, since increased working memory-related neural activity in individuals with or at risk for schizophrenia has been interpreted as ‘neural inefficiency,’ these findings suggest that certain variants of CPLX2 may contribute to impaired brain function in schizophrenia, possibly combined with other deleterious genetic variants, adverse environmental events, or developmental insults.« less

Complexin2 modulates working memory-related neural activity in patients with schizophrenia

DOE PAGES

Hass, Johanna; Walton, Esther; Kirsten, Holger; ...

2014-10-09

The specific contribution of risk or candidate gene variants to the complex phenotype of schizophrenia is largely unknown. Studying the effects of such variants on brain function can provide insight into disease-associated mechanisms on a neural systems level. Previous studies found common variants in the complexin2 ( CPLX2) gene to be highly associated with cognitive dysfunction in schizophrenia patients. Similarly, cognitive functioning was found to be impaired in Cplx2 gene-deficient mice if they were subjected to maternal deprivation or mild brain trauma during puberty. Here, we aimed to study seven common CPLX2 single-nucleotide polymorphisms (SNPs) and their neurogenetic risk mechanismsmore » by investigating their relationship to a schizophrenia-related functional neuroimaging intermediate phenotype. In this paper, we examined functional MRI and genotype data collected from 104 patients with DSM-IV-diagnosed schizophrenia and 122 healthy controls who participated in the Mind Clinical Imaging Consortium study of schizophrenia. Seven SNPs distributed over the whole CPLX2 gene were tested for association with working memory-elicited neural activity in a frontoparietal neural network. Three CPLX2 SNPs were significantly associated with increased neural activity in the dorsolateral prefrontal cortex and intraparietal sulcus in the schizophrenia sample, but showed no association in healthy controls. Finally, since increased working memory-related neural activity in individuals with or at risk for schizophrenia has been interpreted as ‘neural inefficiency,’ these findings suggest that certain variants of CPLX2 may contribute to impaired brain function in schizophrenia, possibly combined with other deleterious genetic variants, adverse environmental events, or developmental insults.« less

Sports and the Growing Musculoskeletal System: Sports Imaging Series.

PubMed

Nguyen, Jie C; Sheehan, Scott E; Davis, Kirkland W; Gill, Kara G

2017-07-01

Increased youth participation in sports has resulted in increased injury tolls due to shifts toward participation in competitive sports at earlier ages, increased training intensity and competition schedules, as well as specialization into one sport. The physiology of the growing musculoskeletal system makes the growing athlete particularly vulnerable to specific types of injuries. Radiologists must understand the differences between pediatric and adult athletes to recognize the particular injuries to which these young athletes are prone. Imaging and pertinent clinical details of major representative acute and overuse injuries characteristic to pediatric athletes will be discussed. © RSNA, 2017.

In vivo single-shot 13C spectroscopic imaging of hyperpolarized metabolites by spatiotemporal encoding

NASA Astrophysics Data System (ADS)

Schmidt, Rita; Laustsen, Christoffer; Dumez, Jean-Nicolas; Kettunen, Mikko I.; Serrao, Eva M.; Marco-Rius, Irene; Brindle, Kevin M.; Ardenkjaer-Larsen, Jan Henrik; Frydman, Lucio

2014-03-01

Hyperpolarized metabolic imaging is a growing field that has provided a new tool for analyzing metabolism, particularly in cancer. Given the short life times of the hyperpolarized signal, fast and effective spectroscopic imaging methods compatible with dynamic metabolic characterizations are necessary. Several approaches have been customized for hyperpolarized 13C MRI, including CSI with a center-out k-space encoding, EPSI, and spectrally selective pulses in combination with spiral EPI acquisitions. Recent studies have described the potential of single-shot alternatives based on spatiotemporal encoding (SPEN) principles, to derive chemical-shift images within a sub-second period. By contrast to EPSI, SPEN does not require oscillating acquisition gradients to deliver chemical-shift information: its signal encodes both spatial as well as chemical shift information, at no extra cost in experimental complexity. SPEN MRI sequences with slice-selection and arbitrary excitation pulses can also be devised, endowing SPEN with the potential to deliver single-shot multi-slice chemical shift images, with a temporal resolution required for hyperpolarized dynamic metabolic imaging. The present work demonstrates this with initial in vivo results obtained from SPEN-based imaging of pyruvate and its metabolic products, after injection of hyperpolarized [1-13C]pyruvate. Multi-slice chemical-shift images of healthy rats were obtained at 4.7 T in the region of the kidney, and 4D (2D spatial, 1D spectral, 1D temporal) data sets were obtained at 7 T from a murine lymphoma tumor model.

In vivo single-shot 13C spectroscopic imaging of hyperpolarized metabolites by spatiotemporal encoding

PubMed Central

Schmidt, Rita; Laustsen, Christoffer; Dumez, Jean-Nicolas; Kettunen, Mikko I.; Serrao, Eva M.; Marco-Rius, Irene; Brindle, Kevin M.; Ardenkjaer-Larsen, Jan Henrik; Frydman, Lucio

2016-01-01

Hyperpolarized metabolic imaging is a growing field that has provided a tool for analyzing metabolism, particularly in cancer. Given the short life times of the hyperpolarized signal, fast and effective spectroscopic imaging methods compatible with dynamic metabolic characterizations are necessary. Several approaches have been customized for hyperpolarized 13C MRI, including CSI with a center-out k-space encoding, EPSI, and spectrally selective pulses in combination with spiral EPI acquisitions. Recent studies have described the potential of single-shot alternatives based on spatiotemporal encoding (SPEN) principles, to derive chemical-shift images within a sub-second period. By contrast to EPSI, SPEN does not require oscillating acquisition gradients to deliver chemical-shift information: its signal encodes both spatial as well as chemical shift information, at no extra cost in experimental complexity. SPEN MRI sequences with slice-selection and arbitrary excitation pulses can also be devised, endowing SPEN with the potential to deliver single-shot multi-slice chemical shift images, with a temporal resolution required for hyperpolarized dynamic metabolic imaging. The present work demonstrates this with initial in vivo results obtained from SPEN-based imaging of pyruvate and its metabolic products, after injection of hyperpolarized [1-13C]pyruvate. Multi-slice chemical-shift images of healthy rats were obtained at 4.7 T in the region of the kidney, and 4D (2D spatial, 1D spectral, 1D temporal) data sets were obtained at 7 T from a murine lymphoma tumor model. PMID:24486720

Performance of unenhanced respiratory-gated 3D SSFP MRA to depict hepatic and visceral artery anatomy and variants.

PubMed

Puippe, Gilbert D; Alkadhi, Hatem; Hunziker, Roger; Nanz, Daniel; Pfammatter, Thomas; Baumueller, Stephan

2012-08-01

To prospectively evaluate the performance of unenhanced respiratory-gated magnetization-prepared 3D-SSFP inversion recovery MRA (unenhanced-MRA) to depict hepatic and visceral artery anatomy and variants in comparison to contrast-enhanced dynamic gradient-echo MRI (CE-MRI) and to digital subtraction angiography (DSA). Eighty-four patients (55.6±12.4 years) were imaged with CE-MRI (TR/TE 3.5/1.7ms, TI 1.7ms, flip-angle 15°) and unenhanced-MRA (TR/TE 4.4/2.2ms, TI 200ms, flip-angle 90°). Two independent readers assessed image quality of hepatic and visceral arteries on a 4-point-scale. Vessel contrast was measured by a third reader. In 28 patients arterial anatomy was compared to DSA. Interobserver agreement regarding image quality was good for CE-MRI (κ=0.77) and excellent for unenhanced-MRA (κ=0.83). Unenhanced-MRA yielded diagnostic image quality in 71.6% of all vessels, whereas CE-MRI provided diagnostic image quality in 90.6% (p<0.001). Vessel-based image quality was significantly superior for all vessels at CE-MRI compared to unenhanced-MRA (p<0.01). Vessel contrast was similar among both sequences (p=0.15). Compared to DSA, CE-MRI and unenhanced-MRA yielded equal accuracy of 92.9-96.4% for depiction of hepatic and visceral artery variants (p=0.93). Unenhanced-MRA provides diagnostic image quality in 72% of hepatic and visceral arteries with no significant difference in vessel contrast and similar accuracy to CE-MRI for depiction of hepatic and visceral anatomy. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

MR arthrography in glenohumeral instability.

PubMed

Van der Woude, H J; Vanhoenacker, F M

2007-01-01

The impact of accurate imaging in the work-up of patients with glenohumeral instability is high. Results of imaging may directly influence the surgeon's strategy to perform an arthroscopic or open treatment for (recurrent) instability. Magnetic resonance (MR) imaging, and MR arthrography in particular, is the optimal technique to detect, localize and characterize injuries of the capsular-labrum complex. Besides TI-weighted sequences with fat suppression in axial, oblique sagital and coronal directions, an additional series in abduction and exoroation position is highly advocated. This ABER series optimally depicts abnormalities of the inferior capsular-labrum complex and partial undersurface tears of the spinatus tendons. Knowledge of different anatomical variants that may mimic labral tears and of variants of the classic Bankart lesion are useful in the analysis of shoulder MR arthrograms in patients with glenohumeral instability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulawik, K., E-mail: kulawik@agh.edu.pl; Buffat, P.A., E-mail: philippe.buffat@epfl.ch; Ecole Polytechnique Fédérale de Lausanne, CIME, Station 12, CH-1015 Lausanne Switzerland

Microstructural characterization of Inconel 718 superalloy after three different heat treatment variants was performed by electron microscopy and electron tomography techniques, taking advantage of recent development in quantitative electron microscopy. Distribution maps of the chemical elements, collected by ChemiSTEM™ EDX system, offer a clear contrast between γ′, γ″, and the γ matrix. It was found that the γ′ phase contains mainly Ni, Al, and Ti, while the γ″ phase contains Ni, Nb, and Ti. Thus application of the Al and Nb STEM–EDX elemental maps enables identification and size measurements of γ′ and γ″ nanoparticles. 3D morphology of γ′ and γ″more » precipitates was examined by electron microscopy and FIB–SEM tomography. Employed methods revealed that in all three heat treatment variants the γ′ particles are almost spheroidal while the γ″ precipitates are mainly elongated-disc shaped. However, the precipitate sizes differed for each variant contributing to differences in the yield strength. Tomographic images were used for estimation of the volume fraction of the both strengthening phases. - Highlights: • ChemiSTEM™ EDX elemental maps bring a fast mean to differentiate γ′ and γ″ particles. • Such maps enable for the explicit size measurements of γ′ and γ″ nanoparticles. • Explicit γ′ and γ″ phases total volume fraction was measured employing FIB–SEM. • γ′/γ″ co-precipitates and sandwich-like γ′/γ″/γ′ particles were present. • HRSTEM-HAADF imaging revealed atomic columns of the γ′/γ″ co-precipitates.« less

Fast Lossless Compression of Multispectral-Image Data

NASA Technical Reports Server (NTRS)

Klimesh, Matthew

2006-01-01

An algorithm that effects fast lossless compression of multispectral-image data is based on low-complexity, proven adaptive-filtering algorithms. This algorithm is intended for use in compressing multispectral-image data aboard spacecraft for transmission to Earth stations. Variants of this algorithm could be useful for lossless compression of three-dimensional medical imagery and, perhaps, for compressing image data in general.

Normal distribution pattern and physiological variants of 68Ga-PSMA-11 PET/CT imaging.

PubMed

Demirci, Emre; Sahin, Onur Erdem; Ocak, Meltem; Akovali, Burak; Nematyazar, Jamal; Kabasakal, Levent

2016-11-01

Ga-PSMA-11 is a novel PET tracer suggested to be used for imaging of advanced prostate cancer. In this study, we aimed to present a detailed biodistribution of Ga-PSMA-11, including physiological and benign variants of prostate-specific membrane antigen (PSMA) imaging. We carried out a retrospective analysis of 40 patients who underwent PSMA PET/computed tomography (CT) imaging and who had no evidence of residual or metastatic disease on the scans. In addition, 16 patients who underwent PSMA PET/CT imaging with any indication other than prostate cancer were included in the study to evaluate physiological uptake in the normal prostate gland. The median, minimum-maximum, and mean standardized uptake value (SUV) values were calculated for visceral organs, bone marrow and lymph nodes, and mucosal areas. Any physiological variants or benign lesions with Ga-PSMA-11 were also noted. Ga-PSMA-11 uptake was noted in the kidneys, parotid and submandibular glands, duodenum, small intestines, spleen, liver, and lacrimal glands, and mucosal uptake in the nasopharynx, vocal cords, pancreas, stomach, mediastinal blood pool, thyroid gland, adrenal gland, rectum, vertebral bone marrow, and testes. Celiac ganglia showed slight Ga-PSMA-11 uptake in 24 of 40 patients without the presence of any other pathologic lymph nodes in abdominal and pelvic areas. Variable uptake of Ga-PSMA-11 was observed in calcified choroid plexus, a thyroid nodule, an adrenal nodule, axillary lymph nodes and celiac ganglia, occasional osteophytes, and gallbladder. The patient group with PSMA PET/CT for indications other than prostate cancer (n=16) showed a slight radiotracer uptake in normal prostate gland (SUVmax: 5.5±1.6, range: 3.5-8.3). This study shows normal distribution pattern, range of SUVs, and physiological variants of Ga-PSMA-11. In addition, several potential pitfalls were documented to prevent misinterpretations of the scan.

Image Processing Of Images From Peripheral-Artery Digital Subtraction Angiography (DSA) Studies

NASA Astrophysics Data System (ADS)

Wilson, David L.; Tarbox, Lawrence R.; Cist, David B.; Faul, David D.

1988-06-01

A system is being developed to test the possibility of doing peripheral, digital subtraction angiography (DSA) with a single contrast injection using a moving gantry system. Given repositioning errors that occur between the mask and contrast-containing images, factors affecting the success of subtractions following image registration have been investigated theoretically and experimentally. For a 1 mm gantry displacement, parallax and geometric image distortion (pin-cushion) both give subtraction errors following registration that are approximately 25% of the error resulting from no registration. Image processing techniques improve the subtractions. The geometric distortion effect is reduced using a piece-wise, 8 parameter unwarping method. Plots of image similarity measures versus pixel shift are well behaved and well fit by a parabola, leading to the development of an iterative, automatic registration algorithm that uses parabolic prediction of the new minimum. The registration algorithm converges quickly (less than 1 second on a MicroVAX) and is relatively immune to the region of interest (ROI) selected.

In vivo liver visualizations with magnetic particle imaging based on the calibration measurement approach

NASA Astrophysics Data System (ADS)

Dieckhoff, J.; Kaul, M. G.; Mummert, T.; Jung, C.; Salamon, J.; Adam, G.; Knopp, T.; Ludwig, F.; Balceris, C.; Ittrich, H.

2017-05-01

Magnetic particle imaging (MPI) facilitates the rapid determination of 3D in vivo magnetic nanoparticle distributions. In this work, liver MPI following intravenous injections of ferucarbotran (Resovist®) was studied. The image reconstruction was based on a calibration measurement, the so called system function. The application of an enhanced system function sample reflecting the particle mobility and aggregation status of ferucarbotran resulted in significantly improved image reconstructions. The finding was supported by characterizations of different ferucarbotran compositions with the magnetorelaxometry and magnetic particle spectroscopy technique. For instance, similar results were obtained between ferucarbotran embedded in freeze-dried mannitol sugar and liver tissue harvested after a ferucarbotran injection. In addition, the combination of multiple shifted measurement patches for a joint reconstruction of the MPI data enlarged the field of view and increased the covering of liver MPI on magnetic resonance images noticeably.

In vivo liver visualizations with magnetic particle imaging based on the calibration measurement approach.

PubMed

Dieckhoff, J; Kaul, M G; Mummert, T; Jung, C; Salamon, J; Adam, G; Knopp, T; Ludwig, F; Balceris, C; Ittrich, H

2017-05-07

Magnetic particle imaging (MPI) facilitates the rapid determination of 3D in vivo magnetic nanoparticle distributions. In this work, liver MPI following intravenous injections of ferucarbotran (Resovist ® ) was studied. The image reconstruction was based on a calibration measurement, the so called system function. The application of an enhanced system function sample reflecting the particle mobility and aggregation status of ferucarbotran resulted in significantly improved image reconstructions. The finding was supported by characterizations of different ferucarbotran compositions with the magnetorelaxometry and magnetic particle spectroscopy technique. For instance, similar results were obtained between ferucarbotran embedded in freeze-dried mannitol sugar and liver tissue harvested after a ferucarbotran injection. In addition, the combination of multiple shifted measurement patches for a joint reconstruction of the MPI data enlarged the field of view and increased the covering of liver MPI on magnetic resonance images noticeably.

Single-shot quantitative phase microscopy with color-multiplexed differential phase contrast (cDPC)

PubMed Central

2017-01-01

We present a new technique for quantitative phase and amplitude microscopy from a single color image with coded illumination. Our system consists of a commercial brightfield microscope with one hardware modification—an inexpensive 3D printed condenser insert. The method, color-multiplexed Differential Phase Contrast (cDPC), is a single-shot variant of Differential Phase Contrast (DPC), which recovers the phase of a sample from images with asymmetric illumination. We employ partially coherent illumination to achieve resolution corresponding to 2× the objective NA. Quantitative phase can then be used to synthesize DIC and phase contrast images or extract shape and density. We demonstrate amplitude and phase recovery at camera-limited frame rates (50 fps) for various in vitro cell samples and c. elegans in a micro-fluidic channel. PMID:28152023

Influence of the limited detector size on spatial variations of the reconstruction accuracy in holographic tomography

NASA Astrophysics Data System (ADS)

Kostencka, Julianna; Kozacki, Tomasz; Hennelly, Bryan; Sheridan, John T.

2017-06-01

Holographic tomography (HT) allows noninvasive, quantitative, 3D imaging of transparent microobjects, such as living biological cells and fiber optics elements. The technique is based on acquisition of multiple scattered fields for various sample perspectives using digital holographic microscopy. Then, the captured data is processed with one of the tomographic reconstruction algorithms, which enables 3D reconstruction of refractive index distribution. In our recent works we addressed the issue of spatially variant accuracy of the HT reconstructions, which results from the insufficient model of diffraction that is applied in the widely-used tomographic reconstruction algorithms basing on the Rytov approximation. In the present study, we continue investigating the spatially variant properties of the HT imaging, however, we are now focusing on the limited spatial size of holograms as a source of this problem. Using the Wigner distribution representation and the Ewald sphere approach, we show that the limited size of the holograms results in a decreased quality of tomographic imaging in off-center regions of the HT reconstructions. This is because the finite detector extent becomes a limiting aperture that prohibits acquisition of full information about diffracted fields coming from the out-of-focus structures of a sample. The incompleteness of the data results in an effective truncation of the tomographic transfer function for the out-of-center regions of the tomographic image. In this paper, the described effect is quantitatively characterized for three types of the tomographic systems: the configuration with 1) object rotation, 2) scanning of the illumination direction, 3) the hybrid HT solution combing both previous approaches.

3D temporal subtraction on multislice CT images using nonlinear warping technique

NASA Astrophysics Data System (ADS)

Ishida, Takayuki; Katsuragawa, Shigehiko; Kawashita, Ikuo; Kim, Hyounseop; Itai, Yoshinori; Awai, Kazuo; Li, Qiang; Doi, Kunio

2007-03-01

The detection of very subtle lesions and/or lesions overlapped with vessels on CT images is a time consuming and difficult task for radiologists. In this study, we have developed a 3D temporal subtraction method to enhance interval changes between previous and current multislice CT images based on a nonlinear image warping technique. Our method provides a subtraction CT image which is obtained by subtraction of a previous CT image from a current CT image. Reduction of misregistration artifacts is important in the temporal subtraction method. Therefore, our computerized method includes global and local image matching techniques for accurate registration of current and previous CT images. For global image matching, we selected the corresponding previous section image for each current section image by using 2D cross-correlation between a blurred low-resolution current CT image and a blurred previous CT image. For local image matching, we applied the 3D template matching technique with translation and rotation of volumes of interests (VOIs) which were selected in the current and the previous CT images. The local shift vector for each VOI pair was determined when the cross-correlation value became the maximum in the 3D template matching. The local shift vectors at all voxels were determined by interpolation of shift vectors of VOIs, and then the previous CT image was nonlinearly warped according to the shift vector for each voxel. Finally, the warped previous CT image was subtracted from the current CT image. The 3D temporal subtraction method was applied to 19 clinical cases. The normal background structures such as vessels, ribs, and heart were removed without large misregistration artifacts. Thus, interval changes due to lung diseases were clearly enhanced as white shadows on subtraction CT images.

Image-Enhancement Aid For The Partially Sighted

NASA Technical Reports Server (NTRS)

Lawton, T. A.; Gennery, D. B.

1989-01-01

Digital filtering enhances ability to read and to recognize objects. Possible to construct portable vision aid by combining miniature video equipment to observe scene and display images with very-large-scale integrated circuits to implement real-time digital image-data processing. Afflicted observer views scene through magnifier to shift spatial frequencies downward and thereby improves perceived image. However, less magnification needed, larger the scene observed. Thus, one measure of effectiveness of new system is amount of magnification required with and without it. In series of tests, found 27 to 70 percent more magnification needed for afflicted observers to recognize unfiltered words than to recognize filtered words.

Imaging-Genetics in Dyslexia: Connecting risk genetic variants to brain neuroimaging and ultimately to reading impairments

PubMed Central

Eicher, John D.; Gruen, Jeffrey R.

2013-01-01

Dyslexia is a common pediatric disorder that affects 5-17% of schoolchildren in the United States. It is marked by unexpected difficulties in fluent reading despite adequate intelligence, opportunity, and instruction. Classically, neuropsychologists have studied dyslexia using a variety of neurocognitive batteries to gain insight into the specific deficits and impairments in affected children. Since dyslexia is a complex genetic trait with high heritability, analyses conditioned on performance on these neurocognitive batteries have been used to try to identify associated genes. This has led to some successes in identifying contributing genes, although much of the heritability remains unexplained. Additionally, the lack of relevant human brain tissue for analysis and the challenges of modeling a uniquely human trait in animals are barriers to advancing our knowledge of the underlying pathophysiology. In vivo imaging technologies, however, present new opportunities to examine dyslexia and reading skills in a clearly relevant context in human subjects. Recent investigations have started to integrate these imaging data with genetic data in attempts to gain a more complete and complex understanding of reading processes. In addition to bridging the gap from genetic risk variant to a discernible neuroimaging phenotype and ultimately to the clinical impairments in reading performance, the use of neuroimaging phenotypes will reveal novel risk genes and variants. In this article, we briefly discuss the genetic and imaging investigations and take an in-depth look at the recent imaging-genetics investigations of dyslexia. PMID:23916419

SU-F-I-10: Spatially Local Statistics for Adaptive Image Filtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iliopoulos, AS; Sun, X; Floros, D

Purpose: To facilitate adaptive image filtering operations, addressing spatial variations in both noise and signal. Such issues are prevalent in cone-beam projections, where physical effects such as X-ray scattering result in spatially variant noise, violating common assumptions of homogeneous noise and challenging conventional filtering approaches to signal extraction and noise suppression. Methods: We present a computational mechanism for probing into and quantifying the spatial variance of noise throughout an image. The mechanism builds a pyramid of local statistics at multiple spatial scales; local statistical information at each scale includes (weighted) mean, median, standard deviation, median absolute deviation, as well asmore » histogram or dynamic range after local mean/median shifting. Based on inter-scale differences of local statistics, the spatial scope of distinguishable noise variation is detected in a semi- or un-supervised manner. Additionally, we propose and demonstrate the incorporation of such information in globally parametrized (i.e., non-adaptive) filters, effectively transforming the latter into spatially adaptive filters. The multi-scale mechanism is materialized by efficient algorithms and implemented in parallel CPU/GPU architectures. Results: We demonstrate the impact of local statistics for adaptive image processing and analysis using cone-beam projections of a Catphan phantom, fitted within an annulus to increase X-ray scattering. The effective spatial scope of local statistics calculations is shown to vary throughout the image domain, necessitating multi-scale noise and signal structure analysis. Filtering results with and without spatial filter adaptation are compared visually, illustrating improvements in imaging signal extraction and noise suppression, and in preserving information in low-contrast regions. Conclusion: Local image statistics can be incorporated in filtering operations to equip them with spatial adaptivity to spatial signal/noise variations. An efficient multi-scale computational mechanism is developed to curtail processing latency. Spatially adaptive filtering may impact subsequent processing tasks such as reconstruction and numerical gradient computations for deformable registration. NIH Grant No. R01-184173.« less