Single Particle Orientation and Rotational Tracking (SPORT) in biophysical studies

NASA Astrophysics Data System (ADS)

Gu, Yan; Ha, Ji Won; Augspurger, Ashley E.; Chen, Kuangcai; Zhu, Shaobin; Fang, Ning

2013-10-01

The single particle orientation and rotational tracking (SPORT) techniques have seen rapid development in the past 5 years. Recent technical advances have greatly expanded the applicability of SPORT in biophysical studies. In this feature article, we survey the current development of SPORT and discuss its potential applications in biophysics, including cellular membrane processes and intracellular transport.The single particle orientation and rotational tracking (SPORT) techniques have seen rapid development in the past 5 years. Recent technical advances have greatly expanded the applicability of SPORT in biophysical studies. In this feature article, we survey the current development of SPORT and discuss its potential applications in biophysics, including cellular membrane processes and intracellular transport. Electronic supplementary information (ESI) available: Three supplementary movies and an experimental section. See DOI: 10.1039/c3nr02254d

Tracking single mRNA molecules in live cells

NASA Astrophysics Data System (ADS)

Moon, Hyungseok C.; Lee, Byung Hun; Lim, Kiseong; Son, Jae Seok; Song, Minho S.; Park, Hye Yoon

2016-06-01

mRNAs inside cells interact with numerous RNA-binding proteins, microRNAs, and ribosomes that together compose a highly heterogeneous population of messenger ribonucleoprotein (mRNP) particles. Perhaps one of the best ways to investigate the complex regulation of mRNA is to observe individual molecules. Single molecule imaging allows the collection of quantitative and statistical data on subpopulations and transient states that are otherwise obscured by ensemble averaging. In addition, single particle tracking reveals the sequence of events that occur in the formation and remodeling of mRNPs in real time. Here, we review the current state-of-the-art techniques in tagging, delivery, and imaging to track single mRNAs in live cells. We also discuss how these techniques are applied to extract dynamic information on the transcription, transport, localization, and translation of mRNAs. These studies demonstrate how single molecule tracking is transforming the understanding of mRNA regulation in live cells.

Faint Debris Detection by Particle Based Track-Before-Detect Method

NASA Astrophysics Data System (ADS)

Uetsuhara, M.; Ikoma, N.

2014-09-01

This study proposes a particle method to detect faint debris, which is hardly seen in single frame, from an image sequence based on the concept of track-before-detect (TBD). The most widely used detection method is detect-before-track (DBT), which firstly detects signals of targets from single frame by distinguishing difference of intensity between foreground and background then associate the signals for each target between frames. DBT is capable of tracking bright targets but limited. DBT is necessary to consider presence of false signals and is difficult to recover from false association. On the other hand, TBD methods try to track targets without explicitly detecting the signals followed by evaluation of goodness of each track and obtaining detection results. TBD has an advantage over DBT in detecting weak signals around background level in single frame. However, conventional TBD methods for debris detection apply brute-force search over candidate tracks then manually select true one from the candidates. To reduce those significant drawbacks of brute-force search and not-fully automated process, this study proposes a faint debris detection algorithm by a particle based TBD method consisting of sequential update of target state and heuristic search of initial state. The state consists of position, velocity direction and magnitude, and size of debris over the image at a single frame. The sequential update process is implemented by a particle filter (PF). PF is an optimal filtering technique that requires initial distribution of target state as a prior knowledge. An evolutional algorithm (EA) is utilized to search the initial distribution. The EA iteratively applies propagation and likelihood evaluation of particles for the same image sequences and resulting set of particles is used as an initial distribution of PF. This paper describes the algorithm of the proposed faint debris detection method. The algorithm demonstrates performance on image sequences acquired during observation campaigns dedicated to GEO breakup fragments, which would contain a sufficient number of faint debris images. The results indicate the proposed method is capable of tracking faint debris with moderate computational costs at operational level.

Symplectic multi-particle tracking on GPUs

NASA Astrophysics Data System (ADS)

Liu, Zhicong; Qiang, Ji

2018-05-01

A symplectic multi-particle tracking model is implemented on the Graphic Processing Units (GPUs) using the Compute Unified Device Architecture (CUDA) language. The symplectic tracking model can preserve phase space structure and reduce non-physical effects in long term simulation, which is important for beam property evaluation in particle accelerators. Though this model is computationally expensive, it is very suitable for parallelization and can be accelerated significantly by using GPUs. In this paper, we optimized the implementation of the symplectic tracking model on both single GPU and multiple GPUs. Using a single GPU processor, the code achieves a factor of 2-10 speedup for a range of problem sizes compared with the time on a single state-of-the-art Central Processing Unit (CPU) node with similar power consumption and semiconductor technology. It also shows good scalability on a multi-GPU cluster at Oak Ridge Leadership Computing Facility. In an application to beam dynamics simulation, the GPU implementation helps save more than a factor of two total computing time in comparison to the CPU implementation.

Selective counting and sizing of single virus particles using fluorescent aptamer-based nanoparticle tracking analysis.

PubMed

Szakács, Zoltán; Mészáros, Tamás; de Jonge, Marien I; Gyurcsányi, Róbert E

2018-05-30

Detection and counting of single virus particles in liquid samples are largely limited to narrow size distribution of viruses and purified formulations. To address these limitations, here we propose a calibration-free method that enables concurrently the selective recognition, counting and sizing of virus particles as demonstrated through the detection of human respiratory syncytial virus (RSV), an enveloped virus with a broad size distribution, in throat swab samples. RSV viruses were selectively labeled through their attachment glycoproteins (G) with fluorescent aptamers, which further enabled their identification, sizing and counting at the single particle level by fluorescent nanoparticle tracking analysis. The proposed approach seems to be generally applicable to virus detection and quantification. Moreover, it could be successfully applied to detect single RSV particles in swab samples of diagnostic relevance. Since the selective recognition is associated with the sizing of each detected particle, this method enables to discriminate viral elements linked to the virus as well as various virus forms and associations.

TrackMate: An open and extensible platform for single-particle tracking.

PubMed

Tinevez, Jean-Yves; Perry, Nick; Schindelin, Johannes; Hoopes, Genevieve M; Reynolds, Gregory D; Laplantine, Emmanuel; Bednarek, Sebastian Y; Shorte, Spencer L; Eliceiri, Kevin W

2017-02-15

We present TrackMate, an open source Fiji plugin for the automated, semi-automated, and manual tracking of single-particles. It offers a versatile and modular solution that works out of the box for end users, through a simple and intuitive user interface. It is also easily scriptable and adaptable, operating equally well on 1D over time, 2D over time, 3D over time, or other single and multi-channel image variants. TrackMate provides several visualization and analysis tools that aid in assessing the relevance of results. The utility of TrackMate is further enhanced through its ability to be readily customized to meet specific tracking problems. TrackMate is an extensible platform where developers can easily write their own detection, particle linking, visualization or analysis algorithms within the TrackMate environment. This evolving framework provides researchers with the opportunity to quickly develop and optimize new algorithms based on existing TrackMate modules without the need of having to write de novo user interfaces, including visualization, analysis and exporting tools. The current capabilities of TrackMate are presented in the context of three different biological problems. First, we perform Caenorhabditis-elegans lineage analysis to assess how light-induced damage during imaging impairs its early development. Our TrackMate-based lineage analysis indicates the lack of a cell-specific light-sensitive mechanism. Second, we investigate the recruitment of NEMO (NF-κB essential modulator) clusters in fibroblasts after stimulation by the cytokine IL-1 and show that photodamage can generate artifacts in the shape of TrackMate characterized movements that confuse motility analysis. Finally, we validate the use of TrackMate for quantitative lifetime analysis of clathrin-mediated endocytosis in plant cells. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Three-dimensional particle tracking via tunable color-encoded multiplexing.

PubMed

Duocastella, Martí; Theriault, Christian; Arnold, Craig B

2016-03-01

We present a novel 3D tracking approach capable of locating single particles with nanometric precision over wide axial ranges. Our method uses a fast acousto-optic liquid lens implemented in a bright field microscope to multiplex light based on color into different and selectable focal planes. By separating the red, green, and blue channels from an image captured with a color camera, information from up to three focal planes can be retrieved. Multiplane information from the particle diffraction rings enables precisely locating and tracking individual objects up to an axial range about 5 times larger than conventional single-plane approaches. We apply our method to the 3D visualization of the well-known coffee-stain phenomenon in evaporating water droplets.

Decorrelation correction for nanoparticle tracking analysis of dilute polydisperse suspensions in bulk flow

NASA Astrophysics Data System (ADS)

Hartman, John; Kirby, Brian

2017-03-01

Nanoparticle tracking analysis, a multiprobe single particle tracking technique, is a widely used method to quickly determine the concentration and size distribution of colloidal particle suspensions. Many popular tools remove non-Brownian components of particle motion by subtracting the ensemble-average displacement at each time step, which is termed dedrifting. Though critical for accurate size measurements, dedrifting is shown here to introduce significant biasing error and can fundamentally limit the dynamic range of particle size that can be measured for dilute heterogeneous suspensions such as biological extracellular vesicles. We report a more accurate estimate of particle mean-square displacement, which we call decorrelation analysis, that accounts for correlations between individual and ensemble particle motion, which are spuriously introduced by dedrifting. Particle tracking simulation and experimental results show that this approach more accurately determines particle diameters for low-concentration polydisperse suspensions when compared with standard dedrifting techniques.

Innovative molecular-based fluorescent nanoparticles for multicolor single particle tracking in cells

NASA Astrophysics Data System (ADS)

Daniel, Jonathan; Godin, Antoine G.; Palayret, Matthieu; Lounis, Brahim; Cognet, Laurent; Blanchard-Desce, Mireille

2016-03-01

Based on an original molecular-based design, we present bright and photostable fluorescent organic nanoparticles (FONs) showing excellent colloidal stability in various aqueous environments. Complementary near-infrared emitting and green emitting FONs were prepared using a simple, fast and robust protocol. Both types of FONs could be simultaneously imaged at the single-particle level in solution as well as in biological environments using a monochromatic excitation and a dual-color fluorescence microscope. No evidence of acute cytotoxicity was found upon incubation of live cells with mixed solutions of FONs, and both types of nanoparticles were found internalized in the cells where their motion could be simultaneously tracked at video-rate up to minutes. These fluorescent organic nanoparticles open a novel non-toxic alternative to existing nanoparticles for imaging biological structures, compatible with live-cell experiments and specially fitted for multicolor single particle tracking.

An analysis of particle track effects on solid mammalian tissues

NASA Technical Reports Server (NTRS)

Todd, P.; Clarkson, T. W. (Principal Investigator)

1992-01-01

Relative biological effectiveness (RBE) and quality factor (Q) at extreme values of linear energy transfer (LET) have been determined on the basis of experiments with single-cell systems and specific tissue responses. In typical single-cell systems, each heavy particle (Ar or Fe) passes through a single cell or no cell. In experiments on animal tissues, however, each heavy particle passes through several cells, and the LET can exceed 200 keV micrometers-1 in every cell. In most laboratory animal tissue systems, however, only a small portion of the hit cells are capable of expressing the end-point being measured, such as cell killing, mutation or carcinogenesis. The following question was therefore addressed: do RBEs and Q factors derived from single-cell experiments properly account for the damage at high LET when multiple cells are hit by HZE tracks? A review is offered in which measured radiation effects and known tissue properties are combined to estimate on the one hand, the number of cells at risk, p3n, per track, where n is the number of cells per track based on tissue and organ geometry, and p3 is the probability that a cell in the track is capable of expressing the experimental end-point. On the other hand, the tissue and single-cell responses are compared by determining the ratio RBE in tissue/RBE in corresponding single cells. Experimental data from the literature indicate that tissue RBEs at very high LET (Fe and Ar ions) are higher than corresponding single-cell RBEs, especially in tissues in which p3n is high.

Fuzzy logic particle tracking velocimetry

NASA Technical Reports Server (NTRS)

Wernet, Mark P.

1993-01-01

Fuzzy logic has proven to be a simple and robust method for process control. Instead of requiring a complex model of the system, a user defined rule base is used to control the process. In this paper the principles of fuzzy logic control are applied to Particle Tracking Velocimetry (PTV). Two frames of digitally recorded, single exposure particle imagery are used as input. The fuzzy processor uses the local particle displacement information to determine the correct particle tracks. Fuzzy PTV is an improvement over traditional PTV techniques which typically require a sequence (greater than 2) of image frames for accurately tracking particles. The fuzzy processor executes in software on a PC without the use of specialized array or fuzzy logic processors. A pair of sample input images with roughly 300 particle images each, results in more than 200 velocity vectors in under 8 seconds of processing time.

Optimal estimates of the diffusion coefficient of a single Brownian trajectory.

PubMed

Boyer, Denis; Dean, David S; Mejía-Monasterio, Carlos; Oshanin, Gleb

2012-03-01

Modern developments in microscopy and image processing are revolutionizing areas of physics, chemistry, and biology as nanoscale objects can be tracked with unprecedented accuracy. The goal of single-particle tracking is to determine the interaction between the particle and its environment. The price paid for having a direct visualization of a single particle is a consequent lack of statistics. Here we address the optimal way to extract diffusion constants from single trajectories for pure Brownian motion. It is shown that the maximum likelihood estimator is much more efficient than the commonly used least-squares estimate. Furthermore, we investigate the effect of disorder on the distribution of estimated diffusion constants and show that it increases the probability of observing estimates much smaller than the true (average) value.

Controlled Synthesis and Fluorescence Tracking of Highly Uniform Poly(N-isopropylacrylamide) Microgels.

PubMed

Virtanen, Otto L J; Purohit, Ashvini; Brugnoni, Monia; Wöll, Dominik; Richtering, Walter

2016-09-08

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this work, we use single particle tracking of fluorescently labeled PNIPAM microgels as a showcase for tuning microgel size by a rapid non-stirred precipitation polymerization procedure. This approach is well suited for prototyping new reaction compositions and conditions or for applications that do not require large amounts of product. Microgel synthesis, particle size and structure determination by dynamic and static light scattering are detailed in the protocol. It is shown that the addition of functional comonomers can have a large influence on the particle nucleation and structure. Single particle tracking by wide-field fluorescence microscopy allows for an investigation of the diffusion of labeled tracer microgels in a concentrated matrix of non-labeled microgels, a system not easily investigated by other methods such as dynamic light scattering.

A multi-parametric particle-pairing algorithm for particle tracking in single and multiphase flows

NASA Astrophysics Data System (ADS)

Cardwell, Nicholas D.; Vlachos, Pavlos P.; Thole, Karen A.

2011-10-01

Multiphase flows (MPFs) offer a rich area of fundamental study with many practical applications. Examples of such flows range from the ingestion of foreign particulates in gas turbines to transport of particles within the human body. Experimental investigation of MPFs, however, is challenging, and requires techniques that simultaneously resolve both the carrier and discrete phases present in the flowfield. This paper presents a new multi-parametric particle-pairing algorithm for particle tracking velocimetry (MP3-PTV) in MPFs. MP3-PTV improves upon previous particle tracking algorithms by employing a novel variable pair-matching algorithm which utilizes displacement preconditioning in combination with estimated particle size and intensity to more effectively and accurately match particle pairs between successive images. To improve the method's efficiency, a new particle identification and segmentation routine was also developed. Validation of the new method was initially performed on two artificial data sets: a traditional single-phase flow published by the Visualization Society of Japan (VSJ) and an in-house generated MPF data set having a bi-modal distribution of particles diameters. Metrics of the measurement yield, reliability and overall tracking efficiency were used for method comparison. On the VSJ data set, the newly presented segmentation routine delivered a twofold improvement in identifying particles when compared to other published methods. For the simulated MPF data set, measurement efficiency of the carrier phases improved from 9% to 41% for MP3-PTV as compared to a traditional hybrid PTV. When employed on experimental data of a gas-solid flow, the MP3-PTV effectively identified the two particle populations and reported a vector efficiency and velocity measurement error comparable to measurements for the single-phase flow images. Simultaneous measurement of the dispersed particle and the carrier flowfield velocities allowed for the calculation of instantaneous particle slip velocities, illustrating the algorithm's strength to robustly and accurately resolve polydispersed MPFs.

Single quantum dot tracking reveals the impact of nanoparticle surface on intracellular state.

PubMed

Zahid, Mohammad U; Ma, Liang; Lim, Sung Jun; Smith, Andrew M

2018-05-08

Inefficient delivery of macromolecules and nanoparticles to intracellular targets is a major bottleneck in drug delivery, genetic engineering, and molecular imaging. Here we apply live-cell single-quantum-dot imaging and tracking to analyze and classify nanoparticle states after intracellular delivery. By merging trajectory diffusion parameters with brightness measurements, multidimensional analysis reveals distinct and heterogeneous populations that are indistinguishable using single parameters alone. We derive new quantitative metrics of particle loading, cluster distribution, and vesicular release in single cells, and evaluate intracellular nanoparticles with diverse surfaces following osmotic delivery. Surface properties have a major impact on cell uptake, but little impact on the absolute cytoplasmic numbers. A key outcome is that stable zwitterionic surfaces yield uniform cytosolic behavior, ideal for imaging agents. We anticipate that this combination of quantum dots and single-particle tracking can be widely applied to design and optimize next-generation imaging probes, nanoparticle therapeutics, and biologics.

A particle filter for multi-target tracking in track before detect context

NASA Astrophysics Data System (ADS)

Amrouche, Naima; Khenchaf, Ali; Berkani, Daoud

2016-10-01

The track-before-detect (TBD) approach can be used to track a single target in a highly noisy radar scene. This is because it makes use of unthresholded observations and incorporates a binary target existence variable into its target state estimation process when implemented as a particle filter (PF). This paper proposes the recursive PF-TBD approach to detect multiple targets in low-signal-to noise ratios (SNR). The algorithm's successful performance is demonstrated using a simulated two target example.

Rapid, topology-based particle tracking for high-resolution measurements of large complex 3D motion fields.

PubMed

Patel, Mohak; Leggett, Susan E; Landauer, Alexander K; Wong, Ian Y; Franck, Christian

2018-04-03

Spatiotemporal tracking of tracer particles or objects of interest can reveal localized behaviors in biological and physical systems. However, existing tracking algorithms are most effective for relatively low numbers of particles that undergo displacements smaller than their typical interparticle separation distance. Here, we demonstrate a single particle tracking algorithm to reconstruct large complex motion fields with large particle numbers, orders of magnitude larger than previously tractably resolvable, thus opening the door for attaining very high Nyquist spatial frequency motion recovery in the images. Our key innovations are feature vectors that encode nearest neighbor positions, a rigorous outlier removal scheme, and an iterative deformation warping scheme. We test this technique for its accuracy and computational efficacy using synthetically and experimentally generated 3D particle images, including non-affine deformation fields in soft materials, complex fluid flows, and cell-generated deformations. We augment this algorithm with additional particle information (e.g., color, size, or shape) to further enhance tracking accuracy for high gradient and large displacement fields. These applications demonstrate that this versatile technique can rapidly track unprecedented numbers of particles to resolve large and complex motion fields in 2D and 3D images, particularly when spatial correlations exist.

A Hidden Markov Model for Single Particle Tracks Quantifies Dynamic Interactions between LFA-1 and the Actin Cytoskeleton

PubMed Central

Das, Raibatak; Cairo, Christopher W.; Coombs, Daniel

2009-01-01

The extraction of hidden information from complex trajectories is a continuing problem in single-particle and single-molecule experiments. Particle trajectories are the result of multiple phenomena, and new methods for revealing changes in molecular processes are needed. We have developed a practical technique that is capable of identifying multiple states of diffusion within experimental trajectories. We model single particle tracks for a membrane-associated protein interacting with a homogeneously distributed binding partner and show that, with certain simplifying assumptions, particle trajectories can be regarded as the outcome of a two-state hidden Markov model. Using simulated trajectories, we demonstrate that this model can be used to identify the key biophysical parameters for such a system, namely the diffusion coefficients of the underlying states, and the rates of transition between them. We use a stochastic optimization scheme to compute maximum likelihood estimates of these parameters. We have applied this analysis to single-particle trajectories of the integrin receptor lymphocyte function-associated antigen-1 (LFA-1) on live T cells. Our analysis reveals that the diffusion of LFA-1 is indeed approximately two-state, and is characterized by large changes in cytoskeletal interactions upon cellular activation. PMID:19893741

Magnetophoretic Conductors and Diodes in a 3D Magnetic Field.

PubMed

Abedini-Nassab, Roozbeh; Joh, Daniel Y; Van Heest, Melissa; Baker, Cody; Chilkoti, Ashutosh; Murdoch, David M; Yellen, Benjamin B

2016-06-14

We demonstrate magnetophoretic conductor tracks that can transport single magnetized beads and magnetically labeled single cells in a 3-dimensional time-varying magnetic field. The vertical field bias, in addition to the in-plane rotating field, has the advantage of reducing the attraction between particles, which inhibits the formation of particle clusters. However, the inclusion of a vertical field requires the re-design of magnetic track geometries which can transport magnetized objects across the substrate. Following insights from magnetic bubble technology, we found that successful magnetic conductor geometries defined in soft magnetic materials must be composed of alternating sections of positive and negative curvature. In addition to the previously studied magnetic tracks taken from the magnetic bubble literature, a drop-shape pattern was found to be even more adept at transporting small magnetic beads and single cells. Symmetric patterns are shown to achieve bi-directional conduction, whereas asymmetric patterns achieve unidirectional conduction. These designs represent the electrical circuit corollaries of the conductor and diode, respectively. Finally, we demonstrate biological applications in transporting single cells and in the size based separation of magnetic particles.

Single-virus tracking approach to reveal the interaction of Dengue virus with autophagy during the early stage of infection

NASA Astrophysics Data System (ADS)

Chu, Li-Wei; Huang, Yi-Lung; Lee, Jin-Hui; Huang, Long-Ying; Chen, Wei-Jun; Lin, Ya-Hsuan; Chen, Jyun-Yu; Xiang, Rui; Lee, Chau-Hwang; Ping, Yueh-Hsin

2014-01-01

Dengue virus (DENV) is one of the major infectious pathogens worldwide. DENV infection is a highly dynamic process. Currently, no antiviral drug is available for treating DENV-induced diseases since little is known regarding how the virus interacts with host cells during infection. Advanced molecular imaging technologies are powerful tools to understand the dynamics of intracellular interactions and molecular trafficking. This study exploited a single-virus particle tracking technology to address whether DENV interacts with autophagy machinery during the early stage of infection. Using confocal microscopy and three-dimensional image analysis, we showed that DENV triggered the formation of green fluorescence protein-fused microtubule-associated protein 1A/1B-light chain 3 (GFP-LC3) puncta, and DENV-induced autophagosomes engulfed DENV particles within 15-min postinfection. Moreover, single-virus particle tracking revealed that both DENV particles and autophagosomes traveled together during the viral infection. Finally, in the presence of autophagy suppressor 3-methyladenine, the replication of DENV was inhibited and the location of DENV particles spread in cytoplasma. In contrast, the numbers of newly synthesized DENV were elevated and the co-localization of DENV particles and autophagosomes was detected while the cells were treated with autophagy inducer rapamycin. Taken together, we propose that DENV particles interact with autophagosomes at the early stage of viral infection, which promotes the replication of DENV.

Three-dimensional simulation of the motion of a single particle under a simulated turbulent velocity field

NASA Astrophysics Data System (ADS)

Moreno-Casas, P. A.; Bombardelli, F. A.

2015-12-01

A 3D Lagrangian particle tracking model is coupled to a 3D channel velocity field to simulate the saltation motion of a single sediment particle moving in saltation mode. The turbulent field is a high-resolution three dimensional velocity field that reproduces a by-pass transition to turbulence on a flat plate due to free-stream turbulence passing above de plate. In order to reduce computational costs, a decoupled approached is used, i.e., the turbulent flow is simulated independently from the tracking model, and then used to feed the 3D Lagrangian particle model. The simulations are carried using the point-particle approach. The particle tracking model contains three sub-models, namely, particle free-flight, a post-collision velocity and bed representation sub-models. The free-flight sub-model considers the action of the following forces: submerged weight, non-linear drag, lift, virtual mass, Magnus and Basset forces. The model also includes the effect of particle angular velocity. The post-collision velocities are obtained by applying conservation of angular and linear momentum. The complete model was validated with experimental results from literature within the sand range. Results for particle velocity time series and distribution of particle turbulent intensities are presented.

Fuzzy inference enhanced information recovery from digital PIV using cross-correlation combined with particle tracking

NASA Technical Reports Server (NTRS)

Wernet, Mark P.

1995-01-01

Particle Image Velocimetry provides a means of measuring the instantaneous 2-component velocity field across a planar region of a seeded flowfield. In this work only two camera, single exposure images are considered where both cameras have the same view of the illumination plane. Two competing techniques which yield unambiguous velocity vector direction information have been widely used for reducing the single exposure, multiple image data: cross-correlation and particle tracking. Correlation techniques yield averaged velocity estimates over subregions of the flow, whereas particle tracking techniques give individual particle velocity estimates. The correlation technique requires identification of the correlation peak on the correlation plane corresponding to the average displacement of particles across the subregion. Noise on the images and particle dropout contribute to spurious peaks on the correlation plane, leading to misidentification of the true correlation peak. The subsequent velocity vector maps contain spurious vectors where the displacement peaks have been improperly identified. Typically these spurious vectors are replaced by a weighted average of the neighboring vectors, thereby decreasing the independence of the measurements. In this work fuzzy logic techniques are used to determine the true correlation displacement peak even when it is not the maximum peak on the correlation plane, hence maximizing the information recovery from the correlation operation, maintaining the number of independent measurements and minimizing the number of spurious velocity vectors. Correlation peaks are correctly identified in both high and low seed density cases. The correlation velocity vector map can then be used as a guide for the particle tracking operation. Again fuzzy logic techniques are used, this time to identify the correct particle image pairings between exposures to determine particle displacements, and thus velocity. The advantage of this technique is the improved spatial resolution which is available from the particle tracking operation. Particle tracking alone may not be possible in the high seed density images typically required for achieving good results from the correlation technique. This two staged approach offers a velocimetric technique capable of measuring particle velocities with high spatial resolution over a broad range of seeding densities.

An automatic, stagnation point based algorithm for the delineation of Wellhead Protection Areas

NASA Astrophysics Data System (ADS)

Tosco, Tiziana; Sethi, Rajandrea; di Molfetta, Antonio

2008-07-01

Time-related capture areas are usually delineated using the backward particle tracking method, releasing circles of equally spaced particles around each well. In this way, an accurate delineation often requires both a very high number of particles and a manual capture zone encirclement. The aim of this work was to propose an Automatic Protection Area (APA) delineation algorithm, which can be coupled with any model of flow and particle tracking. The computational time is here reduced, thanks to the use of a limited number of nonequally spaced particles. The particle starting positions are determined coupling forward particle tracking from the stagnation point, and backward particle tracking from the pumping well. The pathlines are postprocessed for a completely automatic delineation of closed perimeters of time-related capture zones. The APA algorithm was tested for a two-dimensional geometry, in homogeneous and nonhomogeneous aquifers, steady state flow conditions, single and multiple wells. Results show that the APA algorithm is robust and able to automatically and accurately reconstruct protection areas with a very small number of particles, also in complex scenarios.

STED microscopy visualizes energy deposition of single ions in a solid-state detector beyond diffraction limit

NASA Astrophysics Data System (ADS)

Niklas, M.; Henrich, M.; Jäkel, O.; Engelhardt, J.; Abdollahi, A.; Greilich, S.

2017-05-01

Fluorescent nuclear track detectors (FNTDs) allow for visualization of single-particle traversal in clinical ion beams. The point spread function of the confocal readout has so far hindered a more detailed characterization of the track spots—the ion’s characteristic signature left in the FNTD. Here we report on the readout of the FNTD by optical nanoscopy, namely stimulated emission depletion microscopy. It was firstly possible to visualize the track spots of carbon ions and protons beyond the diffraction limit of conventional light microscopy with a resolving power of approximately 80 nm (confocal: 320 nm). A clear discrimination of the spatial width, defined by the full width half maximum of track spots from particles (proton and carbon ions), with a linear energy transfer (LET) ranging from approximately 2-1016 keV µm-1 was possible. Results suggest that the width depends on LET but not on particle charge within the uncertainties. A discrimination of particle type by width thus does not seem possible (as well as with confocal microscopy). The increased resolution, however, could allow for refined determination of the cross-sectional area facing substantial energy deposition. This work could pave the way towards development of optical nanoscopy-based analysis of radiation-induced cellular response using cell-fluorescent ion track hybrid detectors.

TrackArt: the user friendly interface for single molecule tracking data analysis and simulation applied to complex diffusion in mica supported lipid bilayers.

PubMed

Matysik, Artur; Kraut, Rachel S

2014-05-01

Single molecule tracking (SMT) analysis of fluorescently tagged lipid and protein probes is an attractive alternative to ensemble averaged methods such as fluorescence correlation spectroscopy (FCS) or fluorescence recovery after photobleaching (FRAP) for measuring diffusion in artificial and plasma membranes. The meaningful estimation of diffusion coefficients and their errors is however not straightforward, and is heavily dependent on sample type, acquisition method, and equipment used. Many approaches require advanced computing and programming skills for their implementation. Here we present TrackArt software, an accessible graphic interface for simulation and complex analysis of multiple particle paths. Imported trajectories can be filtered to eliminate spurious or corrupted tracks, and are then analyzed using several previously described methodologies, to yield single or multiple diffusion coefficients, their population fractions, and estimated errors. We use TrackArt to analyze the single-molecule diffusion behavior of a sphingolipid analog SM-Atto647N, in mica supported DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) bilayers. Fitting with a two-component diffusion model confirms the existence of two separate populations of diffusing particles in these bilayers on mica. As a demonstration of the TrackArt workflow, we characterize and discuss the effective activation energies required to increase the diffusion rates of these populations, obtained from Arrhenius plots of temperature-dependent diffusion. Finally, TrackArt provides a simulation module, allowing the user to generate models with multiple particle trajectories, diffusing with different characteristics. Maps of domains, acting as impermeable or permeable obstacles for particles diffusing with given rate constants and diffusion coefficients, can be simulated or imported from an image. Importantly, this allows one to use simulated data with a known diffusion behavior as a comparison for results acquired using particular algorithms on actual, "natural" samples whose diffusion behavior is to be extracted. It can also serve as a tool for demonstrating diffusion principles. TrackArt is an open source, platform-independent, Matlab-based graphical user interface, and is easy to use even for those unfamiliar with the Matlab programming environment. TrackArt can be used for accurate simulation and analysis of complex diffusion data, such as diffusion in lipid bilayers, providing publication-quality formatted results.

Heavy ion action on single cells: Cellular inactivation capability of single accelerated heavy ions

NASA Technical Reports Server (NTRS)

Kost, M.; Pross, H.-D.; Russmann, C.; Schneider, E.; Kiefer, J.; Kraft, G.; Lenz, G.; Becher, W.

1994-01-01

Heavy ions (HZE-particles) constitute an important part of radiation in space. Although their number is small the high amount of energy transferred by individual particles may cause severe biological effects. Their investigation requires special techniques which were tested by experiments performed at the UNILAC at the GSI (Darmstadt). Diploid yeast was used which is a suitable eucaryotic test system because of its resistance to extreme conditions like dryness and vacuum. Cells were placed on nuclear track detector foils and exposed to ions of different atomic number and energy. To assess the action of one single ion on an individual cell, track parameters and the respective colony forming abilities (CFA) were determined with the help of computer aided image analysis. There is mounting evidence that not only the amount of energy deposited along the particle path, commonly given by the LET, is of importance but also the spatial problem of energy deposition at a submicroscopical scale. It is virtually impossible to investigate track structure effects in detail with whole cell populations and (globally applied) high particle fluences. It is, therefore, necessary to detect the action of simple ions in individual cells. The results show that the biological action depends on atomic number and specific energy of the impinging ions, which can be compared with model calculations of recent track structure models.

Interactive, computer-assisted tracking of speckle trajectories in fluorescence microscopy: application to actin polymerization and membrane fusion.

PubMed

Smith, Matthew B; Karatekin, Erdem; Gohlke, Andrea; Mizuno, Hiroaki; Watanabe, Naoki; Vavylonis, Dimitrios

2011-10-05

Analysis of particle trajectories in images obtained by fluorescence microscopy reveals biophysical properties such as diffusion coefficient or rates of association and dissociation. Particle tracking and lifetime measurement is often limited by noise, large mobilities, image inhomogeneities, and path crossings. We present Speckle TrackerJ, a tool that addresses some of these challenges using computer-assisted techniques for finding positions and tracking particles in different situations. A dynamic user interface assists in the creation, editing, and refining of particle tracks. The following are results from application of this program: 1), Tracking single molecule diffusion in simulated images. The shape of the diffusing marker on the image changes from speckle to cloud, depending on the relationship of the diffusion coefficient to the camera exposure time. We use these images to illustrate the range of diffusion coefficients that can be measured. 2), We used the program to measure the diffusion coefficient of capping proteins in the lamellipodium. We found values ∼0.5 μm(2)/s, suggesting capping protein association with protein complexes or the membrane. 3), We demonstrate efficient measuring of appearance and disappearance of EGFP-actin speckles within the lamellipodium of motile cells that indicate actin monomer incorporation into the actin filament network. 4), We marked appearance and disappearance events of fluorescently labeled vesicles to supported lipid bilayers and tracked single lipids from the fused vesicle on the bilayer. This is the first time, to our knowledge, that vesicle fusion has been detected with single molecule sensitivity and the program allowed us to perform a quantitative analysis. 5), By discriminating between undocking and fusion events, dwell times for vesicle fusion after vesicle docking to membranes can be measured. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Ghost hunting—an assessment of ghost particle detection and removal methods for tomographic-PIV

NASA Astrophysics Data System (ADS)

Elsinga, G. E.; Tokgoz, S.

2014-08-01

This paper discusses and compares several methods, which aim to remove spurious peaks, i.e. ghost particles, from the volume intensity reconstruction in tomographic-PIV. The assessment is based on numerical simulations of time-resolved tomographic-PIV experiments in linear shear flows. Within the reconstructed volumes, intensity peaks are detected and tracked over time. These peaks are associated with particles (either ghosts or actual particles) and are characterized by their peak intensity, size and track length. Peak intensity and track length are found to be effective in discriminating between most ghosts and the actual particles, although not all ghosts can be detected using only a single threshold. The size of the reconstructed particles does not reveal an important difference between ghosts and actual particles. The joint distribution of peak intensity and track length however does, under certain conditions, allow a complete separation of ghosts and actual particles. The ghosts can have either a high intensity or a long track length, but not both combined, like all the actual particles. Removing the detected ghosts from the reconstructed volume and performing additional MART iterations can decrease the particle position error at low to moderate seeding densities, but increases the position error, velocity error and tracking errors at higher densities. The observed trends in the joint distribution of peak intensity and track length are confirmed by results from a real experiment in laminar Taylor-Couette flow. This diagnostic plot allows an estimate of the number of ghosts that are indistinguishable from the actual particles.

Optical tracking of nanoscale particles in microscale environments

NASA Astrophysics Data System (ADS)

Mathai, P. P.; Liddle, J. A.; Stavis, S. M.

2016-03-01

The trajectories of nanoscale particles through microscale environments record useful information about both the particles and the environments. Optical microscopes provide efficient access to this information through measurements of light in the far field from nanoparticles. Such measurements necessarily involve trade-offs in tracking capabilities. This article presents a measurement framework, based on information theory, that facilitates a more systematic understanding of such trade-offs to rationally design tracking systems for diverse applications. This framework includes the degrees of freedom of optical microscopes, which determine the limitations of tracking measurements in theory. In the laboratory, tracking systems are assemblies of sources and sensors, optics and stages, and nanoparticle emitters. The combined characteristics of such systems determine the limitations of tracking measurements in practice. This article reviews this tracking hardware with a focus on the essential functions of nanoparticles as optical emitters and microenvironmental probes. Within these theoretical and practical limitations, experimentalists have implemented a variety of tracking systems with different capabilities. This article reviews a selection of apparatuses and techniques for tracking multiple and single particles by tuning illumination and detection, and by using feedback and confinement to improve the measurements. Prior information is also useful in many tracking systems and measurements, which apply across a broad spectrum of science and technology. In the context of the framework and review of apparatuses and techniques, this article reviews a selection of applications, with particle diffusion serving as a prelude to tracking measurements in biological, fluid, and material systems, fabrication and assembly processes, and engineered devices. In so doing, this review identifies trends and gaps in particle tracking that might influence future research.

Visualizing interactions between Sindbis virus and cells by single particle tracking

NASA Astrophysics Data System (ADS)

Williard, Mary

2005-03-01

Sindbis virus infects both mammalian and insect cells. Though not pathogenic in humans, Sindbis is a model for many mosquito- borne viruses that cause human disease, such as West Nile virus. We have used real-time single particle fluorescence microscopy to observe individual Sindbis virus particles as they infect living cells. Fluorescent labels were incorporated into both the viral coat proteins and the lipid envelope of the virus. Kinetics characteristic of free diffusion in solution, slower diffusion inside cells, attachment to spots on the cell surface, and motor protein transport inside cells have been observed. Dequenching of the membrane label is used to report membrane fusion events during the infection process. Tracking individual viral particles allows multiple pathways to be determined without the requirement of synchronicity.

Particle image diffusometry: Resolving diffusion coefficient field from microscopy movie data without particle tracking

NASA Astrophysics Data System (ADS)

Hanasaki, Itsuo; Ooi, Yuto

2018-06-01

We propose a technique to evaluate the field of diffusion coefficient for particle dispersion where the Brownian motion is heterogeneous in space and single particle tracking (SPT) analysis is hindered by high concentration of the particles and/or their small size. We realize this "particle image diffusometry" by the principle of the differential dynamic microscopy (DDM). We extend the DDM by introducing the automated objective decision of the scaling regime itself. Label-free evaluation of spatially non-uniform diffusion coefficients without SPT is useful in the diverse applications including crystal nucleation and glass transition where non-invasive observation is desired.

Multicolor Three-Dimensional Tracking for Single-Molecule Fluorescence Resonance Energy Transfer Measurements

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

Keller, Aaron M.; DeVore, Matthew S.; Stich, Dominik G.

Single-molecule fluorescence resonance energy transfer (smFRET) remains a widely utilized and powerful tool for quantifying heterogeneous interactions and conformational dynamics of biomolecules. However, traditional smFRET experiments either are limited to short observation times (typically less than 1 ms) in the case of “burst” confocal measurements or require surface immobilization which usually has a temporal resolution limited by the camera framing rate. We developed a smFRET 3D tracking microscope that is capable of observing single particles for extended periods of time with high temporal resolution. The confocal tracking microscope utilizes closed-loop feedback to follow the particle in solution by recentering itmore » within two overlapping tetrahedral detection elements, corresponding to donor and acceptor channels. We demonstrated the microscope’s multicolor tracking capability via random walk simulations and experimental tracking of 200 nm fluorescent beads in water with a range of apparent smFRET efficiency values, 0.45-0.69. We also demonstrated the microscope’s capability to track and quantify double-stranded DNA undergoing intramolecular smFRET in a viscous glycerol solution. In future experiments, the smFRET 3D tracking system will be used to study protein conformational dynamics while diffusing in solution and native biological environments with high temporal resolution.« less

Multicolor Three-Dimensional Tracking for Single-Molecule Fluorescence Resonance Energy Transfer Measurements

DOE PAGES

Keller, Aaron M.; DeVore, Matthew S.; Stich, Dominik G.; ...

2018-04-19

Single-molecule fluorescence resonance energy transfer (smFRET) remains a widely utilized and powerful tool for quantifying heterogeneous interactions and conformational dynamics of biomolecules. However, traditional smFRET experiments either are limited to short observation times (typically less than 1 ms) in the case of “burst” confocal measurements or require surface immobilization which usually has a temporal resolution limited by the camera framing rate. We developed a smFRET 3D tracking microscope that is capable of observing single particles for extended periods of time with high temporal resolution. The confocal tracking microscope utilizes closed-loop feedback to follow the particle in solution by recentering itmore » within two overlapping tetrahedral detection elements, corresponding to donor and acceptor channels. We demonstrated the microscope’s multicolor tracking capability via random walk simulations and experimental tracking of 200 nm fluorescent beads in water with a range of apparent smFRET efficiency values, 0.45-0.69. We also demonstrated the microscope’s capability to track and quantify double-stranded DNA undergoing intramolecular smFRET in a viscous glycerol solution. In future experiments, the smFRET 3D tracking system will be used to study protein conformational dynamics while diffusing in solution and native biological environments with high temporal resolution.« less

Multishell Au/Ag/SiO 2 nanorods with tunable optical properties as single particle orientation and rotational tracking probes

DOE PAGES

Chen, Kuangcai; Lin, Chia -Cheng; Vela, Javier; ...

2015-04-07

In this study, three-layer core–shell plasmonic nanorods (Au/Ag/SiO 2–NRs), consisting of a gold nanorod core, a thin silver shell, and a thin silica layer, were synthesized and used as optical imaging probes under a differential interference contrast microscope for single particle orientation and rotational tracking. The localized surface plasmon resonance modes were enhanced upon the addition of the silver shell, and the anisotropic optical properties of gold nanorods were maintained. The silica coating enables surface functionalization with silane coupling agents and provides enhanced stability and biocompatibility. Taking advantage of the longitudinal LSPR enhancement, the orientation and rotational information of themore » hybrid nanorods on synthetic lipid bilayers and on live cell membranes were obtained with millisecond temporal resolution using a scientific complementary metal-oxide-semiconductor camera. The results demonstrate that the as-synthesized hybrid nanorods are promising imaging probes with improved sensitivity and good biocompatibility for single plasmonic particle tracking experiments in biological systems.« less

Single particle tracking reveals spatial and dynamic organization of the Escherichia coli biofilm matrix

NASA Astrophysics Data System (ADS)

Birjiniuk, Alona; Billings, Nicole; Nance, Elizabeth; Hanes, Justin; Ribbeck, Katharina; Doyle, Patrick S.

2014-08-01

Biofilms are communities of surface-adherent bacteria surrounded by secreted polymers known as the extracellular polymeric substance. Biofilms are harmful in many industries, and thus it is of great interest to understand their mechanical properties and structure to determine ways to destabilize them. By performing single particle tracking with beads of varying surface functionalization it was found that charge interactions play a key role in mediating mobility within biofilms. With a combination of single particle tracking and microrheological concepts, it was found that Escherichia coli biofilms display height dependent charge density that evolves over time. Statistical analyses of bead trajectories and confocal microscopy showed inter-connecting micron scale channels that penetrate throughout the biofilm, which may be important for nutrient transfer through the system. This methodology provides significant insight into a particular biofilm system and can be applied to many others to provide comparisons of biofilm structure. The elucidation of structure provides evidence for the permeability of biofilms to microscale objects, and the ability of a biofilm to mature and change properties over time.

Controlling Brownian motion of single protein molecules and single fluorophores in aqueous buffer.

PubMed

Cohen, Adam E; Moerner, W E

2008-05-12

We present an Anti-Brownian Electrokinetic trap (ABEL trap) capable of trapping individual fluorescently labeled protein molecules in aqueous buffer. The ABEL trap operates by tracking the Brownian motion of a single fluorescent particle in solution, and applying a time-dependent electric field designed to induce an electrokinetic drift that cancels the Brownian motion. The trapping strength of the ABEL trap is limited by the latency of the feedback loop. In previous versions of the trap, this latency was set by the finite frame rate of the camera used for video-tracking. In the present system, the motion of the particle is tracked entirely in hardware (without a camera or image-processing software) using a rapidly rotating laser focus and lock-in detection. The feedback latency is set by the finite rate of arrival of photons. We demonstrate trapping of individual molecules of the protein GroEL in buffer, and we show confinement of single fluorophores of the dye Cy3 in water.

Three-Dimensional Localization of Single Molecules for Super-Resolution Imaging and Single-Particle Tracking

PubMed Central

von Diezmann, Alex; Shechtman, Yoav; Moerner, W. E.

2017-01-01

Single-molecule super-resolution fluorescence microscopy and single-particle tracking are two imaging modalities that illuminate the properties of cells and materials on spatial scales down to tens of nanometers, or with dynamical information about nanoscale particle motion in the millisecond range, respectively. These methods generally use wide-field microscopes and two-dimensional camera detectors to localize molecules to much higher precision than the diffraction limit. Given the limited total photons available from each single-molecule label, both modalities require careful mathematical analysis and image processing. Much more information can be obtained about the system under study by extending to three-dimensional (3D) single-molecule localization: without this capability, visualization of structures or motions extending in the axial direction can easily be missed or confused, compromising scientific understanding. A variety of methods for obtaining both 3D super-resolution images and 3D tracking information have been devised, each with their own strengths and weaknesses. These include imaging of multiple focal planes, point-spread-function engineering, and interferometric detection. These methods may be compared based on their ability to provide accurate and precise position information of single-molecule emitters with limited photons. To successfully apply and further develop these methods, it is essential to consider many practical concerns, including the effects of optical aberrations, field-dependence in the imaging system, fluorophore labeling density, and registration between different color channels. Selected examples of 3D super-resolution imaging and tracking are described for illustration from a variety of biological contexts and with a variety of methods, demonstrating the power of 3D localization for understanding complex systems. PMID:28151646

Single-Particle Tracking of Human Immunodeficiency Virus Type 1 Productive Entry into Human Primary Macrophages.

PubMed

Li, Qin; Li, Wei; Yin, Wen; Guo, Jia; Zhang, Zhi-Ping; Zeng, Dejun; Zhang, Xiaowei; Wu, Yuntao; Zhang, Xian-En; Cui, Zongqiang

2017-04-25

Macrophages are one of the major targets of human immunodeficiency virus (HIV-1), but the viral entry pathway remains poorly understood in these cells. Noninvasive virus labeling and single-virus tracking are effective tools for studying virus entry. Here, we constructed a quantum dot (QD)-encapsulated infectious HIV-1 particle to track viral entry at a single-particle level in live human primary macrophages. QDs were encapsulated in HIV-1 virions by incorporating viral accessory protein Vpr-conjugated QDs during virus assembly. With the HIV-1 particles encapsulating QDs, we monitored the early phase of viral infection in real time and observed that, during infection, HIV-1 was endocytosed in a clathrin-mediated manner; the particles were translocated into Rab5A-positive endosomes, and the core was released into the cytoplasm by viral envelope-mediated endosomal fusion. Drug inhibition assays verified that endosome fusion contributes to HIV-1 productive infection in primary macrophages. Additionally, we observed that a dynamic actin cytoskeleton is critical for HIV-1 entry and intracellular migration in primary macrophages. HIV-1 dynamics and infection could be blocked by multiple different actin inhibitors. Our study revealed a productive entry pathway in macrophages that requires both endosomal function and actin dynamics, which may assist in the development of inhibitors to block the HIV entry in macrophages.

Optical tracking of nanoscale particles in microscale environments

PubMed Central

Mathai, P. P.; Liddle, J. A.; Stavis, S. M.

2016-01-01

The trajectories of nanoscale particles through microscale environments record useful information about both the particles and the environments. Optical microscopes provide efficient access to this information through measurements of light in the far field from nanoparticles. Such measurements necessarily involve trade-offs in tracking capabilities. This article presents a measurement framework, based on information theory, that facilitates a more systematic understanding of such trade-offs to rationally design tracking systems for diverse applications. This framework includes the degrees of freedom of optical microscopes, which determine the limitations of tracking measurements in theory. In the laboratory, tracking systems are assemblies of sources and sensors, optics and stages, and nanoparticle emitters. The combined characteristics of such systems determine the limitations of tracking measurements in practice. This article reviews this tracking hardware with a focus on the essential functions of nanoparticles as optical emitters and microenvironmental probes. Within these theoretical and practical limitations, experimentalists have implemented a variety of tracking systems with different capabilities. This article reviews a selection of apparatuses and techniques for tracking multiple and single particles by tuning illumination and detection, and by using feedback and confinement to improve the measurements. Prior information is also useful in many tracking systems and measurements, which apply across a broad spectrum of science and technology. In the context of the framework and review of apparatuses and techniques, this article reviews a selection of applications, with particle diffusion serving as a prelude to tracking measurements in biological, fluid, and material systems, fabrication and assembly processes, and engineered devices. In so doing, this review identifies trends and gaps in particle tracking that might influence future research. PMID:27213022

Dosimetry of heavy ions by use of CCD detectors

NASA Technical Reports Server (NTRS)

Schott, J. U.

1994-01-01

The design and the atomic composition of Charge Coupled Devices (CCD's) make them unique for investigations of single energetic particle events. As detector system for ionizing particles they detect single particles with local resolution and near real time particle tracking. In combination with its properties as optical sensor, particle transversals of single particles are to be correlated to any objects attached to the light sensitive surface of the sensor by simple imaging of their shadow and subsequent image analysis of both, optical image and particle effects, observed in affected pixels. With biological objects it is possible for the first time to investigate effects of single heavy ions in tissue or extinguished organs of metabolizing (i.e. moving) systems with a local resolution better than 15 microns. Calibration data for particle detection in CCD's are presented for low energetic protons and heavy ions.

Iterative Track Fitting Using Cluster Classification in Multi Wire Proportional Chamber

NASA Astrophysics Data System (ADS)

Primor, David; Mikenberg, Giora; Etzion, Erez; Messer, Hagit

2007-10-01

This paper addresses the problem of track fitting of a charged particle in a multi wire proportional chamber (MWPC) using cathode readout strips. When a charged particle crosses a MWPC, a positive charge is induced on a cluster of adjacent strips. In the presence of high radiation background, the cluster charge measurements may be contaminated due to background particles, leading to less accurate hit position estimation. The least squares method for track fitting assumes the same position error distribution for all hits and thus loses its optimal properties on contaminated data. For this reason, a new robust algorithm is proposed. The algorithm first uses the known spatial charge distribution caused by a single charged particle over the strips, and classifies the clusters into ldquocleanrdquo and ldquodirtyrdquo clusters. Then, using the classification results, it performs an iterative weighted least squares fitting procedure, updating its optimal weights each iteration. The performance of the suggested algorithm is compared to other track fitting techniques using a simulation of tracks with radiation background. It is shown that the algorithm improves the track fitting performance significantly. A practical implementation of the algorithm is presented for muon track fitting in the cathode strip chamber (CSC) of the ATLAS experiment.

Single track effects, Biostack and risk assessment

NASA Technical Reports Server (NTRS)

Curtis, S. B.; Chatterjee, A. (Principal Investigator)

1994-01-01

The scientific career of Prof. Bucker has spanned a very exciting period in the fledgling science of Space Radiation Biology. The capability for placing biological objects in space was developed, and the methods for properly packaging, retrieving and analyzing them were worked out. Meaningful results on the effects of radiation were obtained for the first time. In fact, many of the successful techniques and methodologies for handling biological samples were developed in Prof. Bucker's laboratories, as attested by the extensive Biostack program. He was the first to suggest and successfully carry out experiments in space directly aimed at measuring effects of single tracks of high-energy heavy galactic cosmic rays by specifically identifying whether or not the object had been hit by a heavy particle track. Because the "hit" frequencies of heavy galactic cosmic rays to cell nuclei in the bodies of space travelers will be low, it is expected that any effects to humans on the cellular level will be dominated by single-track cell traversals. This includes the most important generally recognized late effect of space radiation exposure: radiation-induced cancer. This paper addresses the single-track nature of the space radiation environment, and points out the importance of single "hits" in the evaluation of radiation risk for long-term missions occurring outside the earth's magnetic field. A short review is made of biological objects found to show increased effects when "hit" by a single heavy charged-particle in space. A brief discussion is given of the most provocative results from the bacterial spore Bacillus subtilis: experimental evidence that tracks can affect biological systems at much larger distances from the trajectory than previously suspected, and that the resultant inactivation cross section in space calculated for this system is very large. When taken at face value, the implication of these results, when compared to those from experiments performed at ground-based accelerators with beams at low energies in the same LET range, is that high-energy particles can exert their influence a surprising distance from their trajectory and the inactivation cross sections are some 20 times larger than expected. Clearly, beams from high-energy heavy-ion accelerators should be used to confirm these results. For those end points that can also be caused by low-LET beams such as high-energy protons, it is important to measure their action cross sections as well. The ratio of the cross sections for a high-LET beam to that of a low-LET beam is an interesting experimental ratio and, we suggest, of more intrinsic interest than the RBE (Relative Biological Effectiveness). It is a measure of the "biological" importance of one particle type relative to another particle type. This ratio will be introduced and given the name RPPE (Relative Per Particle Effectiveness). Values of RPPE have appeared in the literature and will be discussed. A rather well-known value of this quantity (13,520) has been suggested for the RPPE of high-energy iron ions to high-energy protons. This value was suggested by Letaw et al. Nature 330, 709-710 (1987)] we will call it the Letaw limit. It will be discussed in terms of the importance of the heavy-ion component vs light-ion component of the galactic cosmic rays. It is also pointed out, however, that there may be unique effects from single tracks of heavy ions that do not occur from light-ion tracks. For such effects, the concepts of both RBE and RPPE lose their meaning.

Improved estimation of anomalous diffusion exponents in single-particle tracking experiments

NASA Astrophysics Data System (ADS)

Kepten, Eldad; Bronshtein, Irena; Garini, Yuval

2013-05-01

The mean square displacement is a central tool in the analysis of single-particle tracking experiments, shedding light on various biophysical phenomena. Frequently, parameters are extracted by performing time averages on single-particle trajectories followed by ensemble averaging. This procedure, however, suffers from two systematic errors when applied to particles that perform anomalous diffusion. The first is significant at short-time lags and is induced by measurement errors. The second arises from the natural heterogeneity in biophysical systems. We show how to estimate and correct these two errors and improve the estimation of the anomalous parameters for the whole particle distribution. As a consequence, we manage to characterize ensembles of heterogeneous particles even for rather short and noisy measurements where regular time-averaged mean square displacement analysis fails. We apply this method to both simulations and in vivo measurements of telomere diffusion in 3T3 mouse embryonic fibroblast cells. The motion of telomeres is found to be subdiffusive with an average exponent constant in time. Individual telomere exponents are normally distributed around the average exponent. The proposed methodology has the potential to improve experimental accuracy while maintaining lower experimental costs and complexity.

Wavelet-based tracking of bacteria in unreconstructed off-axis holograms.

PubMed

Marin, Zach; Wallace, J Kent; Nadeau, Jay; Khalil, Andre

2018-03-01

We propose an automated wavelet-based method of tracking particles in unreconstructed off-axis holograms to provide rough estimates of the presence of motion and particle trajectories in digital holographic microscopy (DHM) time series. The wavelet transform modulus maxima segmentation method is adapted and tailored to extract Airy-like diffraction disks, which represent bacteria, from DHM time series. In this exploratory analysis, the method shows potential for estimating bacterial tracks in low-particle-density time series, based on a preliminary analysis of both living and dead Serratia marcescens, and for rapidly providing a single-bit answer to whether a sample chamber contains living or dead microbes or is empty. Copyright © 2017 Elsevier Inc. All rights reserved.

Automatic three-dimensional tracking of particles with high-numerical-aperture digital lensless holographic microscopy.

PubMed

Restrepo, John F; Garcia-Sucerquia, Jorge

2012-02-15

We present an automatic procedure for 3D tracking of micrometer-sized particles with high-NA digital lensless holographic microscopy. The method uses a two-feature approach to search for the best focal planes and to distinguish particles from artifacts or other elements on the reconstructed stream of the holograms. A set of reconstructed images is axially projected onto a single image. From the projected image, the centers of mass of all the reconstructed elements are identified. Starting from the centers of mass, the morphology of the profile of the maximum intensity along the reconstruction direction allows for the distinguishing of particles from others elements. The method is tested with modeled holograms and applied to automatically track micrometer-sized bubbles in a sample of 4 mm3 of soda.

Optimum Value of Original Events on the Pept Technique

NASA Astrophysics Data System (ADS)

Sadremomtaz, Alireza; Taherparvar, Payvand

2011-12-01

Do Positron emission particle tracking (PEPT) has been used to track the motion of a single radioactively labeled tracer particle within a bed of similar particles. In this paper, the effect of the original event fraction on the results precise in two experiments has been reviewed. Results showed that the algorithm can no longer distinguish some corrupt trajectories, in addition to; further iteration reduces the statistical significance of the sample without improving its quality. Results show that the optimum value of trajectories depends on the type of experiment.

Exploring cytoplasmic dynamics in zebrafish yolk cells by single particle tracking of fluorescent nanodiamonds

NASA Astrophysics Data System (ADS)

Chang, Cheng-Chun; Zhang, Bailin; Li, Che-Yu; Hsieh, Chih-Chien; Duclos, Guillaume; Treussart, François; Chang, Huan-Cheng

2012-02-01

Fluorescent nanodiamonds (FNDs) have recently developed into an exciting new tool for bioimaging applications. The material possesses several unique features including high biocompatibility, easy bioconjugation, and perfect photostability, making it a promising optical nanoprobe in vitro as well as in vivo. This work explores the potential application of this novel nanomaterial as a photostable, nontoxic tracer in vivo using zebrafish as a model organism. We introduced FNDs into the yolk of a zebrafish embryo by microinjection at the 1-cell stage. Movements of the injected particles were investigated by using single particle tracking techniques. We observed unidirectional and stop-and-go traffic as part of the intricate cytoplasmic movements in the yolk cell. We determined a velocity in the range of 0.19 - 0.40 μm/s for 40 particles moving along with the axial streaming in the early developmental stage (1 to 2 hours post fertilization) of the zebrafish embryos.

Single particle tracking of internalized metallic nanoparticles reveals heterogeneous directed motion after clathrin dependent endocytosis in mouse chromaffin cells

NASA Astrophysics Data System (ADS)

Gabriel, Manuela; Moya-Díaz, José; Gallo, Luciana I.; Marengo, Fernando D.; Estrada, Laura C.

2018-01-01

Most accepted single particle tracking methods are able to obtain high-resolution trajectories for relatively short periods of time. In this work we apply a straightforward combination of single-particle tracking microscopy and metallic nanoparticles internalization on mouse chromaffin cells to unveil the intracellular trafficking mechanism of metallic-nanoparticle-loaded vesicles (MNP-V) complexes after clathrin dependent endocytosis. We found that directed transport is the major route of MNP-Vs intracellular trafficking after stimulation (92.6% of the trajectories measured). We then studied the MNP-V speed at each point along the trajectory, and found that the application of a second depolarization stimulus during the tracking provokes an increase in the percentage of low-speed trajectory points in parallel with a decrease in the number of high-speed trajectory points. This result suggests that stimulation may facilitate the compartmentalization of internalized MNPs in a more restricted location such as was already demonstrated in neuronal and neuroendocrine cells (Bronfman et al 2003 J. Neurosci. 23 3209-20). Although further experiments will be required to address the mechanisms underlying this transport dynamics, our studies provide quantitative evidence of the heterogeneous behavior of vesicles mobility after endocytosis in chromaffin cells highlighting the potential of MNPs as alternative labels in optical microscopy to provide new insights into the vesicles dynamics in a wide variety of cellular environments.

Capillarity creates single-crystal calcite nanowires from amorphous calcium carbonate.

PubMed

Kim, Yi-Yeoun; Hetherington, Nicola B J; Noel, Elizabeth H; Kröger, Roland; Charnock, John M; Christenson, Hugo K; Meldrum, Fiona C

2011-12-23

Single-crystal calcite nanowires are formed by crystallization of morphologically equivalent amorphous calcium carbonate (ACC) particles within the pores of track etch membranes. The polyaspartic acid stabilized ACC is drawn into the membrane pores by capillary action, and the single-crystal nature of the nanowires is attributed to the limited contact of the intramembrane ACC particle with the bulk solution. The reaction environment then supports transformation to a single-crystal product. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fuzzy Logic Particle Tracking

NASA Technical Reports Server (NTRS)

2005-01-01

A new all-electronic Particle Image Velocimetry technique that can efficiently map high speed gas flows has been developed in-house at the NASA Lewis Research Center. Particle Image Velocimetry is an optical technique for measuring the instantaneous two component velocity field across a planar region of a seeded flow field. A pulsed laser light sheet is used to illuminate the seed particles entrained in the flow field at two instances in time. One or more charged coupled device (CCD) cameras can be used to record the instantaneous positions of particles. Using the time between light sheet pulses and determining either the individual particle displacements or the average displacement of particles over a small subregion of the recorded image enables the calculation of the fluid velocity. Fuzzy logic minimizes the required operator intervention in identifying particles and computing velocity. Using two cameras that have the same view of the illumination plane yields two single exposure image frames. Two competing techniques that yield unambiguous velocity vector direction information have been widely used for reducing the single-exposure, multiple image frame data: (1) cross-correlation and (2) particle tracking. Correlation techniques yield averaged velocity estimates over subregions of the flow, whereas particle tracking techniques give individual particle velocity estimates. For the correlation technique, the correlation peak corresponding to the average displacement of particles across the subregion must be identified. Noise on the images and particle dropout result in misidentification of the true correlation peak. The subsequent velocity vector maps contain spurious vectors where the displacement peaks have been improperly identified. Typically these spurious vectors are replaced by a weighted average of the neighboring vectors, thereby decreasing the independence of the measurements. In this work, fuzzy logic techniques are used to determine the true correlation displacement peak even when it is not the maximum peak, hence maximizing the information recovery from the correlation operation, maintaining the number of independent measurements, and minimizing the number of spurious velocity vectors. Correlation peaks are correctly identified in both high and low seed density cases. The correlation velocity vector map can then be used as a guide for the particle-tracking operation. Again fuzzy logic techniques are used, this time to identify the correct particle image pairings between exposures to determine particle displacements, and thus the velocity. Combining these two techniques makes use of the higher spatial resolution available from the particle tracking. Particle tracking alone may not be possible in the high seed density images typically required for achieving good results from the correlation technique. This two-staged velocimetric technique can measure particle velocities with high spatial resolution over a broad range of seeding densities.

Robust model-based analysis of single-particle tracking experiments with Spot-On

PubMed Central

Grimm, Jonathan B; Lavis, Luke D

2018-01-01

Single-particle tracking (SPT) has become an important method to bridge biochemistry and cell biology since it allows direct observation of protein binding and diffusion dynamics in live cells. However, accurately inferring information from SPT studies is challenging due to biases in both data analysis and experimental design. To address analysis bias, we introduce ‘Spot-On’, an intuitive web-interface. Spot-On implements a kinetic modeling framework that accounts for known biases, including molecules moving out-of-focus, and robustly infers diffusion constants and subpopulations from pooled single-molecule trajectories. To minimize inherent experimental biases, we implement and validate stroboscopic photo-activation SPT (spaSPT), which minimizes motion-blur bias and tracking errors. We validate Spot-On using experimentally realistic simulations and show that Spot-On outperforms other methods. We then apply Spot-On to spaSPT data from live mammalian cells spanning a wide range of nuclear dynamics and demonstrate that Spot-On consistently and robustly infers subpopulation fractions and diffusion constants. PMID:29300163

Robust model-based analysis of single-particle tracking experiments with Spot-On.

PubMed

Hansen, Anders S; Woringer, Maxime; Grimm, Jonathan B; Lavis, Luke D; Tjian, Robert; Darzacq, Xavier

2018-01-04

Single-particle tracking (SPT) has become an important method to bridge biochemistry and cell biology since it allows direct observation of protein binding and diffusion dynamics in live cells. However, accurately inferring information from SPT studies is challenging due to biases in both data analysis and experimental design. To address analysis bias, we introduce 'Spot-On', an intuitive web-interface. Spot-On implements a kinetic modeling framework that accounts for known biases, including molecules moving out-of-focus, and robustly infers diffusion constants and subpopulations from pooled single-molecule trajectories. To minimize inherent experimental biases, we implement and validate stroboscopic photo-activation SPT (spaSPT), which minimizes motion-blur bias and tracking errors. We validate Spot-On using experimentally realistic simulations and show that Spot-On outperforms other methods. We then apply Spot-On to spaSPT data from live mammalian cells spanning a wide range of nuclear dynamics and demonstrate that Spot-On consistently and robustly infers subpopulation fractions and diffusion constants. © 2018, Hansen et al.

Single α-particle irradiation permits real-time visualization of RNF8 accumulation at DNA damaged sites

NASA Astrophysics Data System (ADS)

Muggiolu, Giovanna; Pomorski, Michal; Claverie, Gérard; Berthet, Guillaume; Mer-Calfati, Christine; Saada, Samuel; Devès, Guillaume; Simon, Marina; Seznec, Hervé; Barberet, Philippe

2017-01-01

As well as being a significant source of environmental radiation exposure, α-particles are increasingly considered for use in targeted radiation therapy. A better understanding of α-particle induced damage at the DNA scale can be achieved by following their tracks in real-time in targeted living cells. Focused α-particle microbeams can facilitate this but, due to their low energy (up to a few MeV) and limited range, α-particles detection, delivery, and follow-up observations of radiation-induced damage remain difficult. In this study, we developed a thin Boron-doped Nano-Crystalline Diamond membrane that allows reliable single α-particles detection and single cell irradiation with negligible beam scattering. The radiation-induced responses of single 3 MeV α-particles delivered with focused microbeam are visualized in situ over thirty minutes after irradiation by the accumulation of the GFP-tagged RNF8 protein at DNA damaged sites.

Particle displacement tracking applied to air flows

NASA Technical Reports Server (NTRS)

Wernet, Mark P.

1991-01-01

Electronic Particle Image Velocimeter (PIV) techniques offer many advantages over conventional photographic PIV methods such as fast turn around times and simplified data reduction. A new all electronic PIV technique was developed which can measure high speed gas velocities. The Particle Displacement Tracking (PDT) technique employs a single cw laser, small seed particles (1 micron), and a single intensified, gated CCD array frame camera to provide a simple and fast method of obtaining two-dimensional velocity vector maps with unambiguous direction determination. Use of a single CCD camera eliminates registration difficulties encountered when multiple cameras are used to obtain velocity magnitude and direction information. An 80386 PC equipped with a large memory buffer frame-grabber board provides all of the data acquisition and data reduction operations. No array processors of other numerical processing hardware are required. Full video resolution (640x480 pixel) is maintained in the acquired images, providing high resolution video frames of the recorded particle images. The time between data acquisition to display of the velocity vector map is less than 40 sec. The new electronic PDT technique is demonstrated on an air nozzle flow with velocities less than 150 m/s.

Real-time detection method and system for identifying individual aerosol particles

DOEpatents

Gard, Eric E [San Francisco, CA; Coffee, Keith R [Patterson, CA; Frank, Matthias [Oakland, CA; Tobias, Herbert J [Kensington, CA; Fergenson, David P [Alamo, CA; Madden, Norm [Livermore, CA; Riot, Vincent J [Berkeley, CA; Steele, Paul T [Livermore, CA; Woods, Bruce W [Livermore, CA

2007-08-21

An improved method and system of identifying individual aerosol particles in real time. Sample aerosol particles are collimated, tracked, and screened to determine which ones qualify for mass spectrometric analysis based on predetermined qualification or selection criteria. Screening techniques include one or more of determining particle size, shape, symmetry, and fluorescence. Only qualifying particles passing all screening criteria are subject to desorption/ionization and single particle mass spectrometry to produce corresponding test spectra, which is used to determine the identities of each of the qualifying aerosol particles by comparing the test spectra against predetermined spectra for known particle types. In this manner, activation cycling of a particle ablation laser of a single particle mass spectrometer is reduced.

A simple and rapid method for high-resolution visualization of single-ion tracks

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

Omichi, Masaaki; Center for Collaborative Research, Anan National College of Technology, Anan, Tokushima 774-0017; Choi, Wookjin

2014-11-15

Prompt determination of spatial points of single-ion tracks plays a key role in high-energy particle induced-cancer therapy and gene/plant mutations. In this study, a simple method for the high-resolution visualization of single-ion tracks without etching was developed through the use of polyacrylic acid (PAA)-N, N’-methylene bisacrylamide (MBAAm) blend films. One of the steps of the proposed method includes exposure of the irradiated films to water vapor for several minutes. Water vapor was found to promote the cross-linking reaction of PAA and MBAAm to form a bulky cross-linked structure; the ion-track scars were detectable at a nanometer scale by atomic forcemore » microscopy. This study demonstrated that each scar is easily distinguishable, and the amount of generated radicals of the ion tracks can be estimated by measuring the height of the scars, even in highly dense ion tracks. This method is suitable for the visualization of the penumbra region in a single-ion track with a high spatial resolution of 50 nm, which is sufficiently small to confirm that a single ion hits a cell nucleus with a size ranging between 5 and 20 μm.« less

Lineage mapper: A versatile cell and particle tracker

NASA Astrophysics Data System (ADS)

Chalfoun, Joe; Majurski, Michael; Dima, Alden; Halter, Michael; Bhadriraju, Kiran; Brady, Mary

2016-11-01

The ability to accurately track cells and particles from images is critical to many biomedical problems. To address this, we developed Lineage Mapper, an open-source tracker for time-lapse images of biological cells, colonies, and particles. Lineage Mapper tracks objects independently of the segmentation method, detects mitosis in confluence, separates cell clumps mistakenly segmented as a single cell, provides accuracy and scalability even on terabyte-sized datasets, and creates division and/or fusion lineages. Lineage Mapper has been tested and validated on multiple biological and simulated problems. The software is available in ImageJ and Matlab at isg.nist.gov.

Dynamical measurements of motion behavior of free fluorescent sphere using the wide field temporal focusing microscopy with astigmatism method (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lien, Chi-Hsiang; Lin, Chun-Yu; Chen, Shean-Jen; Chien, Fan-Ching

2017-02-01

A three-dimensional (3D) single fluorescent particle tracking strategy based on temporal focusing multiphoton excitation microscopy (TFMPEM) combined with astigmatism imaging is proposed for delivering nanoscale-level axial information that reveals 3D trajectories of single fluorospheres in the axially-resolved multiphoton excitation volume without z-axis scanning. It provides the dynamical ability by measuring the diffusion coefficient of fluorospheres in glycerol solutions with a position standard deviation of 14 nm and 21 nm in the lateral and axial direction and a frame rate of 100 Hz. Moreover, the optical trapping force based on the TFMPEM is minimized to avoid the interference in the tracing measurements compared to that in the spatial focusing MPE approaches. Therefore, we presented a three dimensional single particle tracking strategy to overcome the limitation of the time resolution of the multiphoton imaging using fast frame rate of TFMPEM, and provide three dimensional locations of multiple particles using an astigmatism method.

Particle Filtering for Obstacle Tracking in UAS Sense and Avoid Applications

PubMed Central

Moccia, Antonio

2014-01-01

Obstacle detection and tracking is a key function for UAS sense and avoid applications. In fact, obstacles in the flight path must be detected and tracked in an accurate and timely manner in order to execute a collision avoidance maneuver in case of collision threat. The most important parameter for the assessment of a collision risk is the Distance at Closest Point of Approach, that is, the predicted minimum distance between own aircraft and intruder for assigned current position and speed. Since assessed methodologies can cause some loss of accuracy due to nonlinearities, advanced filtering methodologies, such as particle filters, can provide more accurate estimates of the target state in case of nonlinear problems, thus improving system performance in terms of collision risk estimation. The paper focuses on algorithm development and performance evaluation for an obstacle tracking system based on a particle filter. The particle filter algorithm was tested in off-line simulations based on data gathered during flight tests. In particular, radar-based tracking was considered in order to evaluate the impact of particle filtering in a single sensor framework. The analysis shows some accuracy improvements in the estimation of Distance at Closest Point of Approach, thus reducing the delay in collision detection. PMID:25105154

Tracking single-particle rotation during macrophage uptake

DOE PAGES

Sanchez, Lucero; Patton, Paul; Anthony, Stephen Michael; ...

2015-06-10

We investigated the rotational dynamics of single microparticles during their internalization by macrophage cells. The microparticles used were triblock patchy particles that display two fluorescent patches on their two poles. The optical anisotropy made it possible to directly visualize and quantify the orientation and rotation of the particles. We show that particles exhibit a mixture of fast and slow rotation as they are uptaken by macrophages and transiently undergo directional rotation during their entry into the cell. As a result, the size of the particles and the surface presentation of ligands exerted a negligible influence on this heterogeneity of particlemore » rotation.« less

High-speed (20 kHz) digital in-line holography for transient particle tracking and sizing in multiphase flows

DOE PAGES

Guildenbecher, Daniel R.; Cooper, Marcia A.; Sojka, Paul E.

2016-04-05

High-speed (20 kHz) digital in-line holography (DIH) is applied for 3D quantification of the size and velocity of fragments formed from the impact of a single water drop onto a thin film of water and burning aluminum particles from the combustion of a solid rocket propellant. To address the depth-of-focus problem in DIH, a regression-based multiframe tracking algorithm is employed, and out-of-plane experimental displacement accuracy is shown to be improved by an order-of-magnitude. Comparison of the results with previous DIH measurements using low-speed recording shows improved positional accuracy with the added advantage of detailed resolution of transient dynamics from singlemore » experimental realizations. Furthermore, the method is shown to be particularly advantageous for quantification of particle mass flow rates. For the investigated particle fields, the mass flows rates, which have been automatically measured from single experimental realizations, are found to be within 8% of the expected values.« less

Three-dimensional single-particle tracking in live cells: news from the third dimension

NASA Astrophysics Data System (ADS)

Dupont, A.; Gorelashvili, M.; Schüller, V.; Wehnekamp, F.; Arcizet, D.; Katayama, Y.; Lamb, D. C.; Heinrich, D.

2013-07-01

Single-particle tracking (SPT) is of growing importance in the biophysical community. It is used to investigate processes such as drug and gene delivery, viral uptake, intracellular trafficking or membrane-bound protein mobility. Traditionally, SPT is performed in two dimensions (2D) because of its technical simplicity. However, life occurs in three dimensions (3D) and many methods have been recently developed to track particles in 3D. Now, is the third dimension worth the effort? Here we investigate the differences between the 2D and 3D analyses of intracellular transport with the 3D development of a time-resolved mean square displacement (MSD) analysis introduced previously. The 3D trajectories, and the 2D projections, of fluorescent nanoparticles were obtained with an orbital tracking microscope in two different cell types: in Dictyostelium discoideum ameba and in adherent, more flattened HuH-7 human cells. As expected from the different 3D organization of both cells’ cytoskeletons, a third of the active transport was lost upon projection in the ameba whereas the identification of the active phases was barely affected in the HuH-7 cells. In both cell types, we found intracellular diffusion to be anisotropic and the diffusion coefficient values derived from the 2D analysis were therefore biased.

Dancing the night away: Improving the persistence of locomotion on the micron scale

NASA Astrophysics Data System (ADS)

Gehrels, Emily W.; Rogers, W. Benjamin; Zeravcic, Zorana; Manoharan, Vinothan N.

In recent years a range of nano and microscale walkers (motors that are able to move along a preformed track) have been developed. Many of these walkers bind to their tracks using a single binding site at each station along the track. A disadvantage of these systems is that any failure involving a single site becoming unbound leads to the walker falling off of the track and locomotion being prematurely terminated. For this reason, it has been difficult to develop a motor that can reliably take more than a few sequential steps. We present an experimental system of DNA-functionalized colloidal particles which exhibit directed motion along patterned substrates in response to temperature cycling. Many DNA bridges form between each pair of interacting particles, adding redundancy to the binding at each station to realize a system that should be able to consistently take many steps. We take advantage of toehold exchange in the design of the DNA sequences that mediate the colloidal interactions to produce broadened, flat, or even re-entrant binding and unbinding transitions between the particles and substrate. Using this new freedom of design, we devise systems where, by thermal ratcheting, we can externally control the direction of motion and sequence of steps of the colloidal motor.

Single particle tracking through highly scattering media with multiplexed two-photon excitation

NASA Astrophysics Data System (ADS)

Perillo, Evan; Liu, Yen-Liang; Liu, Cong; Yeh, Hsin-Chih; Dunn, Andrew K.

2015-03-01

3D single-particle tracking (SPT) has been a pivotal tool to furthering our understanding of dynamic cellular processes in complex biological systems, with a molecular localization accuracy (10-100 nm) often better than the diffraction limit of light. However, current SPT techniques utilize either CCDs or a confocal detection scheme which not only suffer from poor temporal resolution but also limit tracking to a depth less than one scattering mean free path in the sample (typically <15μm). In this report we highlight our novel design for a spatiotemporally multiplexed two-photon microscope which is able to reach sub-diffraction-limit tracking accuracy and sub-millisecond temporal resolution, but with a dramatically extended SPT range of up to 200 μm through dense cell samples. We have validated our microscope by tracking (1) fluorescent nanoparticles in a prescribed motion inside gelatin gel (with 1% intralipid) and (2) labeled single EGFR complexes inside skin cancer spheroids (at least 8 layers of cells thick) for ~10 minutes. Furthermore we discuss future capabilities of our multiplexed two-photon microscope design, specifically to the extension of (1) simultaneous multicolor tracking (i.e. spatiotemporal co-localization analysis) and (2) FRET studies (i.e. lifetime analysis). The high resolution, high depth penetration, and multicolor features of this microscope make it well poised to study a variety of molecular scale dynamics in the cell, especially related to cellular trafficking studies with in vitro tumor models and in vivo.

Tracking molecular dynamics without tracking: image correlation of photo-activation microscopy

NASA Astrophysics Data System (ADS)

Pandžić, Elvis; Rossy, Jérémie; Gaus, Katharina

2015-03-01

Measuring protein dynamics in the plasma membrane can provide insights into the mechanisms of receptor signaling and other cellular functions. To quantify protein dynamics on the single molecule level over the entire cell surface, sophisticated approaches such as single particle tracking (SPT), photo-activation localization microscopy (PALM) and fluctuation-based analysis have been developed. However, analyzing molecular dynamics of fluorescent particles with intermittent excitation and low signal-to-noise ratio present at high densities has remained a challenge. We overcame this problem by applying spatio-temporal image correlation spectroscopy (STICS) analysis to photo-activated (PA) microscopy time series. In order to determine under which imaging conditions this approach is valid, we simulated PA images of diffusing particles in a homogeneous environment and varied photo-activation, reversible blinking and irreversible photo-bleaching rates. Further, we simulated data with high particle densities that populated mobile objects (such as adhesions and vesicles) that often interfere with STICS and fluctuation-based analysis. We demonstrated in experimental measurements that the diffusion coefficient of the epidermal growth factor receptor (EGFR) fused to PAGFP in live COS-7 cells can be determined in the plasma membrane and revealed differences in the time-dependent diffusion maps between wild-type and mutant Lck in activated T cells. In summary, we have developed a new analysis approach for live cell photo-activation microscopy data based on image correlation spectroscopy to quantify the spatio-temporal dynamics of single proteins.

Tracking molecular dynamics without tracking: image correlation of photo-activation microscopy.

PubMed

Pandžić, Elvis; Rossy, Jérémie; Gaus, Katharina

2015-03-09

Measuring protein dynamics in the plasma membrane can provide insights into the mechanisms of receptor signaling and other cellular functions. To quantify protein dynamics on the single molecule level over the entire cell surface, sophisticated approaches such as single particle tracking (SPT), photo-activation localization microscopy (PALM) and fluctuation-based analysis have been developed. However, analyzing molecular dynamics of fluorescent particles with intermittent excitation and low signal-to-noise ratio present at high densities has remained a challenge. We overcame this problem by applying spatio-temporal image correlation spectroscopy (STICS) analysis to photo-activated (PA) microscopy time series. In order to determine under which imaging conditions this approach is valid, we simulated PA images of diffusing particles in a homogeneous environment and varied photo-activation, reversible blinking and irreversible photo-bleaching rates. Further, we simulated data with high particle densities that populated mobile objects (such as adhesions and vesicles) that often interfere with STICS and fluctuation-based analysis. We demonstrated in experimental measurements that the diffusion coefficient of the epidermal growth factor receptor (EGFR) fused to PAGFP in live COS-7 cells can be determined in the plasma membrane and revealed differences in the time-dependent diffusion maps between wild-type and mutant Lck in activated T cells. In summary, we have developed a new analysis approach for live cell photo-activation microscopy data based on image correlation spectroscopy to quantify the spatio-temporal dynamics of single proteins.

An efficient fluorescent single-particle position tracking system for long-term pulsed measurements of nitrogen-vacancy centers in diamond

NASA Astrophysics Data System (ADS)

Kim, Kiho; Yun, Jiwon; Lee, Donghyuck; Kim, Dohun

2018-02-01

A simple and convenient design enables real-time three-dimensional position tracking of nitrogen-vacancy (NV) centers in diamond. The system consists entirely of commercially available components (a single-photon counter, a high-speed digital-to-analog converter, a phase-sensitive detector-based feedback device, and a piezo stage), eliminating the need for custom programming or rigorous optimization processes. With a large input range of counters and trackers combined with high sensitivity of single-photon counting, high-speed position tracking (upper bound recovery time of 0.9 s upon 250 nm of step-like positional shift) not only of bright ensembles, but also of low-photon-collection-efficiency single to few NV centers (down to 103 s-1) is possible. The tracking requires position modulation of only 10 nm, which allows simultaneous position tracking and pulsed measurements in the long term. Therefore, this tracking system enables measuring a single-spin magnetic resonance and Rabi oscillations at a very high resolution even without photon collection optimization. The system is widely applicable to various fields related to NV center quantum manipulation research such as NV optical trapping, NV tracking in fluid dynamics, and biological sensing using NV centers inside a biological cell.

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

Forest, E.; Hirata, Kohji

A methodological discussion is given for single particle beam dynamics in circular machines. The discussions are introductory, but (or, even therefore) we avoid to rely on too much simplified concepts. We treat things from a very general and fundamental point of view, because this is the easiest and rightest way to teach how to simulate particle motion and how to analyze its results. We give some principles of particle tracking free from theoretical prejudices. We also introduce some transparent methods to deduce the necessary information from the tracking: many of the traditional beam-dynamics concepts can be abstracted from them asmore » approximate quantities which are valid in certain limiting cases.« less

Objective comparison of particle tracking methods.

PubMed

Chenouard, Nicolas; Smal, Ihor; de Chaumont, Fabrice; Maška, Martin; Sbalzarini, Ivo F; Gong, Yuanhao; Cardinale, Janick; Carthel, Craig; Coraluppi, Stefano; Winter, Mark; Cohen, Andrew R; Godinez, William J; Rohr, Karl; Kalaidzidis, Yannis; Liang, Liang; Duncan, James; Shen, Hongying; Xu, Yingke; Magnusson, Klas E G; Jaldén, Joakim; Blau, Helen M; Paul-Gilloteaux, Perrine; Roudot, Philippe; Kervrann, Charles; Waharte, François; Tinevez, Jean-Yves; Shorte, Spencer L; Willemse, Joost; Celler, Katherine; van Wezel, Gilles P; Dan, Han-Wei; Tsai, Yuh-Show; Ortiz de Solórzano, Carlos; Olivo-Marin, Jean-Christophe; Meijering, Erik

2014-03-01

Particle tracking is of key importance for quantitative analysis of intracellular dynamic processes from time-lapse microscopy image data. Because manually detecting and following large numbers of individual particles is not feasible, automated computational methods have been developed for these tasks by many groups. Aiming to perform an objective comparison of methods, we gathered the community and organized an open competition in which participating teams applied their own methods independently to a commonly defined data set including diverse scenarios. Performance was assessed using commonly defined measures. Although no single method performed best across all scenarios, the results revealed clear differences between the various approaches, leading to notable practical conclusions for users and developers.

Nonlinear dynamic model for visual object tracking on Grassmann manifolds with partial occlusion handling.

PubMed

Khan, Zulfiqar Hasan; Gu, Irene Yu-Hua

2013-12-01

This paper proposes a novel Bayesian online learning and tracking scheme for video objects on Grassmann manifolds. Although manifold visual object tracking is promising, large and fast nonplanar (or out-of-plane) pose changes and long-term partial occlusions of deformable objects in video remain a challenge that limits the tracking performance. The proposed method tackles these problems with the main novelties on: 1) online estimation of object appearances on Grassmann manifolds; 2) optimal criterion-based occlusion handling for online updating of object appearances; 3) a nonlinear dynamic model for both the appearance basis matrix and its velocity; and 4) Bayesian formulations, separately for the tracking process and the online learning process, that are realized by employing two particle filters: one is on the manifold for generating appearance particles and another on the linear space for generating affine box particles. Tracking and online updating are performed in an alternating fashion to mitigate the tracking drift. Experiments using the proposed tracker on videos captured by a single dynamic/static camera have shown robust tracking performance, particularly for scenarios when target objects contain significant nonplanar pose changes and long-term partial occlusions. Comparisons with eight existing state-of-the-art/most relevant manifold/nonmanifold trackers with evaluations have provided further support to the proposed scheme.

Time-Lapse Monitoring of DNA Damage Colocalized With Particle Tracks in Single Living Cells

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

McFadden, Conor H.; Hallacy, Timothy M.; Department of Physics and Astronomy, Rice University, Houston, Texas

2016-09-01

Purpose: Understanding the DNA damage and repair induced by hadron therapy (HT) beams is crucial for developing novel strategies to maximize the use of HT beams to treat cancer patients. However, spatiotemporal studies of DNA damage and repair for beam energies relevant to HT have been challenging. We report a technique that enables spatiotemporal measurement of radiation-induced damage in live cells and colocalization of this damage with charged particle tracks over a broad range of clinically relevant beam energies. The technique uses novel fluorescence nuclear track detectors with fluorescence confocal laser scanning microscopy in the beam line to visualize particlemore » track traversals within the subcellular compartments of live cells within seconds after injury. Methods and Materials: We designed and built a portable fluorescence confocal laser scanning microscope for use in the beam path, coated fluorescence nuclear track detectors with fluorescent-tagged live cells (HT1080 expressing enhanced green fluorescent protein tagged to XRCC1, a single-strand break repair protein), placed the entire assembly into a proton therapy beam line, and irradiated the cells with a fluence of ∼1 × 10{sup 6} protons/cm{sup 2}. Results: We successfully obtained confocal images of proton tracks and foci of DNA single-strand breaks immediately after irradiation. Conclusions: This technique represents an innovative method for analyzing biological responses in any HT beam line at energies and dose rates relevant to therapy. It allows precise determination of the number of tracks traversing a subcellular compartment and monitoring the cellular damage therein, and has the potential to measure the linear energy transfer of each track from therapeutic beams.« less

Magnetophoretic circuits for digital control of single particles and cells

NASA Astrophysics Data System (ADS)

Lim, Byeonghwa; Reddy, Venu; Hu, Xinghao; Kim, Kunwoo; Jadhav, Mital; Abedini-Nassab, Roozbeh; Noh, Young-Woock; Lim, Yong Taik; Yellen, Benjamin B.; Kim, Cheolgi

2014-05-01

The ability to manipulate small fluid droplets, colloidal particles and single cells with the precision and parallelization of modern-day computer hardware has profound applications for biochemical detection, gene sequencing, chemical synthesis and highly parallel analysis of single cells. Drawing inspiration from general circuit theory and magnetic bubble technology, here we demonstrate a class of integrated circuits for executing sequential and parallel, timed operations on an ensemble of single particles and cells. The integrated circuits are constructed from lithographically defined, overlaid patterns of magnetic film and current lines. The magnetic patterns passively control particles similar to electrical conductors, diodes and capacitors. The current lines actively switch particles between different tracks similar to gated electrical transistors. When combined into arrays and driven by a rotating magnetic field clock, these integrated circuits have general multiplexing properties and enable the precise control of magnetizable objects.

Feature aided Monte Carlo probabilistic data association filter for ballistic missile tracking

NASA Astrophysics Data System (ADS)

Ozdemir, Onur; Niu, Ruixin; Varshney, Pramod K.; Drozd, Andrew L.; Loe, Richard

2011-05-01

The problem of ballistic missile tracking in the presence of clutter is investigated. Probabilistic data association filter (PDAF) is utilized as the basic filtering algorithm. We propose to use sequential Monte Carlo methods, i.e., particle filters, aided with amplitude information (AI) in order to improve the tracking performance of a single target in clutter when severe nonlinearities exist in the system. We call this approach "Monte Carlo probabilistic data association filter with amplitude information (MCPDAF-AI)." Furthermore, we formulate a realistic problem in the sense that we use simulated radar cross section (RCS) data for a missile warhead and a cylinder chaff using Lucernhammer1, a state of the art electromagnetic signature prediction software, to model target and clutter amplitude returns as additional amplitude features which help to improve data association and tracking performance. A performance comparison is carried out between the extended Kalman filter (EKF) and the particle filter under various scenarios using single and multiple sensors. The results show that, when only one sensor is used, the MCPDAF performs significantly better than the EKF in terms of tracking accuracy under severe nonlinear conditions for ballistic missile tracking applications. However, when the number of sensors is increased, even under severe nonlinear conditions, the EKF performs as well as the MCPDAF.

Probing the type of anomalous diffusion with single-particle tracking.

PubMed

Ernst, Dominique; Köhler, Jürgen; Weiss, Matthias

2014-05-07

Many reactions in complex fluids, e.g. signaling cascades in the cytoplasm of living cells, are governed by a diffusion-driven encounter of reactants. Yet, diffusion in complex fluids often exhibits an anomalous characteristic ('subdiffusion'). Since different types of subdiffusion have distinct effects on timing and equilibria of chemical reactions, a thorough determination of the reactants' type of random walk is key to a quantitative understanding of reactions in complex fluids. Here we introduce a straightforward and simple approach for determining the type of subdiffusion from single-particle tracking data. Unlike previous approaches, our method also is sensitive to transient subdiffusion phenomena, e.g. obstructed diffusion below the percolation threshold. We validate our strategy with data from experiment and simulation.

NM-Scale Anatomy of an Entire Stardust Carrot Track

NASA Technical Reports Server (NTRS)

Nakamura-Messenger, K.; Keller, L. P.; Clemett, S. J.; Messenger, S.

2009-01-01

Comet Wild-2 samples collected by NASA s Stardust mission are extremely complex, heterogeneous, and have experienced wide ranges of alteration during the capture process. There are two major types of track morphologies: "carrot" and "bulbous," that reflect different structural/compositional properties of the impactors. Carrot type tracks are typically produced by compact or single mineral grains which survive essentially intact as a single large terminal particle. Bulbous tracks are likely produced by fine-grained or organic-rich impactors [1]. Owing to their challenging nature and especially high value of Stardust samples, we have invested considerable effort in developing both sample preparation and analytical techniques tailored for Stardust sample analyses. Our report focuses on our systematic disassembly and coordinated analysis of Stardust carrot track #112 from the mm to nm-scale.

Tracking in 4 dimensions

DOE PAGES

Cartiglia, N.; Arcidiacono, R.; Baldassarri, B.; ...

2016-06-03

In this contribution we will review the progresses toward the construction of a tracking system able to measure the passage of charged particles with a combined precision of ~10 ps and ~10 μm, either using a single type of sensor, able to concurrently measure position and time, or a combination of position and time sensors.

Tracking quasi-stationary flow of weak fluorescent signals by adaptive multi-frame correlation.

PubMed

Ji, L; Danuser, G

2005-12-01

We have developed a novel cross-correlation technique to probe quasi-stationary flow of fluorescent signals in live cells at a spatial resolution that is close to single particle tracking. By correlating image blocks between pairs of consecutive frames and integrating their correlation scores over multiple frame pairs, uncertainty in identifying a globally significant maximum in the correlation score function has been greatly reduced as compared with conventional correlation-based tracking using the signal of only two consecutive frames. This approach proves robust and very effective in analysing images with a weak, noise-perturbed signal contrast where texture characteristics cannot be matched between only a pair of frames. It can also be applied to images that lack prominent features that could be utilized for particle tracking or feature-based template matching. Furthermore, owing to the integration of correlation scores over multiple frames, the method can handle signals with substantial frame-to-frame intensity variation where conventional correlation-based tracking fails. We tested the performance of the method by tracking polymer flow in actin and microtubule cytoskeleton structures labelled at various fluorophore densities providing imagery with a broad range of signal modulation and noise. In applications to fluorescent speckle microscopy (FSM), where the fluorophore density is sufficiently low to reveal patterns of discrete fluorescent marks referred to as speckles, we combined the multi-frame correlation approach proposed above with particle tracking. This hybrid approach allowed us to follow single speckles robustly in areas of high speckle density and fast flow, where previously published FSM analysis methods were unsuccessful. Thus, we can now probe cytoskeleton polymer dynamics in living cells at an entirely new level of complexity and with unprecedented detail.

Spectral characterization of laser-accelerated protons with CR-39 nuclear track detector.

PubMed

Seimetz, M; Bellido, P; García, P; Mur, P; Iborra, A; Soriano, A; Hülber, T; García López, J; Jiménez-Ramos, M C; Lera, R; Ruiz-de la Cruz, A; Sánchez, I; Zaffino, R; Roso, L; Benlloch, J M

2018-02-01

CR-39 nuclear track material is frequently used for the detection of protons accelerated in laser-plasma interactions. The measurement of track densities allows for determination of particle angular distributions, and information on the kinetic energy can be obtained by the use of passive absorbers. We present a precise method of measuring spectral distributions of laser-accelerated protons in a single etching and analysis process. We make use of a one-to-one relation between proton energy and track size and present a precise calibration based on monoenergetic particle beams. While this relation is limited to proton energies below 1 MeV, we show that the range of spectral measurements can be significantly extended by simultaneous use of absorbers of suitable thicknesses. Examples from laser-plasma interactions are presented, and quantitative results on proton energies and particle numbers are compared to those obtained from a time-of-flight detector. The spectrum end points of continuous energy distributions have been determined with both detector types and coincide within 50-100 keV.

Single-particle tracking of endocytosis and exocytosis of single-walled carbon nanotubes in NIH-3T3 cells.

PubMed

Jin, Hong; Heller, Daniel A; Strano, Michael S

2008-06-01

Over 10000 individual trajectories of nonphotobleaching single-walled carbon nanotubes (SWNT) were tracked as they are incorporated into and expelled from NIH-3T3 cells in real time on a perfusion microscope stage. An analysis of mean square displacement allows the complete construction of the mechanistic steps involved from single duration experiments. We observe the first conclusive evidence of SWNT exocytosis and show that the rate closely matches the endocytosis rate with negligible temporal offset. We identify and study the endocytosis and exocytosis pathway that leads to the previously observed aggregation and accumulation of SWNT within the cells.

Particle tracking by using single coefficient of Wigner-Ville distribution

NASA Astrophysics Data System (ADS)

Widjaja, J.; Dawprateep, S.; Chuamchaitrakool, P.; Meemon, P.

2016-11-01

A new method for extracting information from particle holograms by using a single coefficient of Wigner-Ville distribution (WVD) is proposed to obviate drawbacks of conventional numerical reconstructions. Our previous study found that analysis of the holograms by using the WVD gives output coefficients which are mainly confined along a diagonal direction intercepted at the origin of the WVD plane. The slope of this diagonal direction is inversely proportional to the particle position. One of these coefficients always has minimum amplitude, regardless of the particle position. By detecting position of the coefficient with minimum amplitude in the WVD plane, the particle position can be accurately measured. The proposed method is verified through computer simulations.

Development and applications of single particle orientation and rotational tracking in dynamic systems

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

Chen, Kuangcai

The goal of this study is to help with future data analysis and experiment designs in rotational dynamics research using DIC-based SPORT technique. Most of the current studies using DIC-based SPORT techniques are technical demonstrations. Understanding the mechanisms behind the observed rotational behaviors of the imaging probes should be the focus of the future SPORT studies. More efforts are still needed in the development of new imaging probes, particle tracking methods, instrumentations, and advanced data analysis methods to further extend the potential of DIC-based SPORT technique.

Low pressure cold spraying on materials with low erosion resistance

NASA Astrophysics Data System (ADS)

Shikalov, V. S.; Klinkov, S. V.; Kosarev, V. F.

2017-10-01

In present work, the erosion-adhesion transition was investigated during cold spraying of aluminum particles on brittle ceramic substrates. Cold spraying was carried out with aid of sonic nozzle, which use allows significantly reducing the gas stagnation pressure without the effect of flow separation inside the nozzle and, accordingly, reducing the velocity of the spraying particles. Two stagnation pressures were chosen. The coating tracks were sprayed at different air temperatures in nozzle pre-chamber under each of regimes. Single sprayed tracks were obtained and their profiles were investigated by optical profilometry.

Counterion-enhanced cyanine dye loading into lipid nano-droplets for single-particle tracking in zebrafish.

PubMed

Kilin, Vasyl N; Anton, Halina; Anton, Nicolas; Steed, Emily; Vermot, Julien; Vandamme, Thierry F; Mely, Yves; Klymchenko, Andrey S

2014-06-01

Superior brightness of fluorescent nanoparticles places them far ahead of the classical fluorescent dyes in the field of biological imaging. However, for in vivo applications, inorganic nanoparticles, such as quantum dots, are limited due to the lack of biodegradability. Nano-emulsions encapsulating high concentrations of organic dyes are an attractive alternative, but classical fluorescent dyes are inconvenient due to their poor solubility in the oil and their tendency to form non-fluorescent aggregates. This problem was solved here for a cationic cyanine dye (DiI) by substituting its perchlorate counterion for a bulky and hydrophobic tetraphenylborate. This new dye salt, due to its exceptional oil solubility, could be loaded at 8 wt% concentration into nano-droplets of controlled size in the range 30-90 nm. Our 90 nm droplets, which contained >10,000 cyanine molecules, were >100-fold brighter than quantum dots. This extreme brightness allowed, for the first time, single-particle tracking in the blood flow of live zebrafish embryo, revealing both the slow and fast phases of the cardiac cycle. These nano-droplets showed minimal cytotoxicity in cell culture and in the zebrafish embryo. The concept of counterion-based dye loading provides a new effective route to ultra-bright lipid nanoparticles, which enables tracking single particles in live animals, a new dimension of in vivo imaging. Copyright © 2014 Elsevier Ltd. All rights reserved.

Tracking of multiple targets using online learning for reference model adaptation.

PubMed

Pernkopf, Franz

2008-12-01

Recently, much work has been done in multiple object tracking on the one hand and on reference model adaptation for a single-object tracker on the other side. In this paper, we do both tracking of multiple objects (faces of people) in a meeting scenario and online learning to incrementally update the models of the tracked objects to account for appearance changes during tracking. Additionally, we automatically initialize and terminate tracking of individual objects based on low-level features, i.e., face color, face size, and object movement. Many methods unlike our approach assume that the target region has been initialized by hand in the first frame. For tracking, a particle filter is incorporated to propagate sample distributions over time. We discuss the close relationship between our implemented tracker based on particle filters and genetic algorithms. Numerous experiments on meeting data demonstrate the capabilities of our tracking approach. Additionally, we provide an empirical verification of the reference model learning during tracking of indoor and outdoor scenes which supports a more robust tracking. Therefore, we report the average of the standard deviation of the trajectories over numerous tracking runs depending on the learning rate.

Quantum measurement and orientation tracking of fluorescent nanodiamonds inside living cells

NASA Astrophysics Data System (ADS)

McGuinness, L. P.; Yan, Y.; Stacey, A.; Simpson, D. A.; Hall, L. T.; MacLaurin, D.; Prawer, S.; Mulvaney, P.; Wrachtrup, J.; Caruso, F.; Scholten, R. E.; Hollenberg, L. C. L.

2011-06-01

Fluorescent particles are routinely used to probe biological processes. The quantum properties of single spins within fluorescent particles have been explored in the field of nanoscale magnetometry, but not yet in biological environments. Here, we demonstrate optically detected magnetic resonance of individual fluorescent nanodiamond nitrogen-vacancy centres inside living human HeLa cells, and measure their location, orientation, spin levels and spin coherence times with nanoscale precision. Quantum coherence was measured through Rabi and spin-echo sequences over long (>10 h) periods, and orientation was tracked with effective 1° angular precision over acquisition times of 89 ms. The quantum spin levels served as fingerprints, allowing individual centres with identical fluorescence to be identified and tracked simultaneously. Furthermore, monitoring decoherence rates in response to changes in the local environment may provide new information about intracellular processes. The experiments reported here demonstrate the viability of controlled single spin probes for nanomagnetometry in biological systems, opening up a host of new possibilities for quantum-based imaging in the life sciences.

Objective comparison of particle tracking methods

PubMed Central

Chenouard, Nicolas; Smal, Ihor; de Chaumont, Fabrice; Maška, Martin; Sbalzarini, Ivo F.; Gong, Yuanhao; Cardinale, Janick; Carthel, Craig; Coraluppi, Stefano; Winter, Mark; Cohen, Andrew R.; Godinez, William J.; Rohr, Karl; Kalaidzidis, Yannis; Liang, Liang; Duncan, James; Shen, Hongying; Xu, Yingke; Magnusson, Klas E. G.; Jaldén, Joakim; Blau, Helen M.; Paul-Gilloteaux, Perrine; Roudot, Philippe; Kervrann, Charles; Waharte, François; Tinevez, Jean-Yves; Shorte, Spencer L.; Willemse, Joost; Celler, Katherine; van Wezel, Gilles P.; Dan, Han-Wei; Tsai, Yuh-Show; de Solórzano, Carlos Ortiz; Olivo-Marin, Jean-Christophe; Meijering, Erik

2014-01-01

Particle tracking is of key importance for quantitative analysis of intracellular dynamic processes from time-lapse microscopy image data. Since manually detecting and following large numbers of individual particles is not feasible, automated computational methods have been developed for these tasks by many groups. Aiming to perform an objective comparison of methods, we gathered the community and organized, for the first time, an open competition, in which participating teams applied their own methods independently to a commonly defined data set including diverse scenarios. Performance was assessed using commonly defined measures. Although no single method performed best across all scenarios, the results revealed clear differences between the various approaches, leading to important practical conclusions for users and developers. PMID:24441936

Accumulative Difference Image Protocol for Particle Tracking in Fluorescence Microscopy Tested in Mouse Lymphonodes

PubMed Central

Villa, Carlo E.; Caccia, Michele; Sironi, Laura; D'Alfonso, Laura; Collini, Maddalena; Rivolta, Ilaria; Miserocchi, Giuseppe; Gorletta, Tatiana; Zanoni, Ivan; Granucci, Francesca; Chirico, Giuseppe

2010-01-01

The basic research in cell biology and in medical sciences makes large use of imaging tools mainly based on confocal fluorescence and, more recently, on non-linear excitation microscopy. Substantially the aim is the recognition of selected targets in the image and their tracking in time. We have developed a particle tracking algorithm optimized for low signal/noise images with a minimum set of requirements on the target size and with no a priori knowledge of the type of motion. The image segmentation, based on a combination of size sensitive filters, does not rely on edge detection and is tailored for targets acquired at low resolution as in most of the in-vivo studies. The particle tracking is performed by building, from a stack of Accumulative Difference Images, a single 2D image in which the motion of the whole set of the particles is coded in time by a color level. This algorithm, tested here on solid-lipid nanoparticles diffusing within cells and on lymphocytes diffusing in lymphonodes, appears to be particularly useful for the cellular and the in-vivo microscopy image processing in which few a priori assumption on the type, the extent and the variability of particle motions, can be done. PMID:20808918

Accumulative difference image protocol for particle tracking in fluorescence microscopy tested in mouse lymphonodes.

PubMed

Villa, Carlo E; Caccia, Michele; Sironi, Laura; D'Alfonso, Laura; Collini, Maddalena; Rivolta, Ilaria; Miserocchi, Giuseppe; Gorletta, Tatiana; Zanoni, Ivan; Granucci, Francesca; Chirico, Giuseppe

2010-08-17

The basic research in cell biology and in medical sciences makes large use of imaging tools mainly based on confocal fluorescence and, more recently, on non-linear excitation microscopy. Substantially the aim is the recognition of selected targets in the image and their tracking in time. We have developed a particle tracking algorithm optimized for low signal/noise images with a minimum set of requirements on the target size and with no a priori knowledge of the type of motion. The image segmentation, based on a combination of size sensitive filters, does not rely on edge detection and is tailored for targets acquired at low resolution as in most of the in-vivo studies. The particle tracking is performed by building, from a stack of Accumulative Difference Images, a single 2D image in which the motion of the whole set of the particles is coded in time by a color level. This algorithm, tested here on solid-lipid nanoparticles diffusing within cells and on lymphocytes diffusing in lymphonodes, appears to be particularly useful for the cellular and the in-vivo microscopy image processing in which few a priori assumption on the type, the extent and the variability of particle motions, can be done.

Comparison of three-dimensional particle tracking and sizing using plenoptic imaging and digital in-line holography.

PubMed

Hall, Elise M; Thurow, Brian S; Guildenbecher, Daniel R

2016-08-10

Digital in-line holography (DIH) and plenoptic photography are two techniques for single-shot, volumetric measurement of 3D particle fields. Here we present a comparison of the two methods by applying plenoptic imaging to experimental configurations that have been previously investigated with DIH. These experiments include the tracking of secondary droplets from the impact of a water drop on a thin film of water and tracking of pellets from a shotgun. Both plenoptic imaging and DIH successfully quantify the 3D nature of these particle fields. This includes measurement of the 3D particle position, individual particle sizes, and three-component velocity vectors. For the initial processing methods presented here, both techniques give out-of-plane positional accuracy of approximately 1-2 particle diameters. For a fixed image sensor, digital holography achieves higher effective in-plane spatial resolutions. However, collimated and coherent illumination makes holography susceptible to image distortion through index of refraction gradients, as demonstrated in the shotgun experiments. In contrast, plenoptic imaging allows for a simpler experimental configuration and, due to the use of diffuse, white-light illumination, plenoptic imaging is less susceptible to image distortion in the shotgun experiments.

Tracking Debris Shed by a Space-Shuttle Launch Vehicle

NASA Technical Reports Server (NTRS)

Stuart, Phillip C.; Rogers, Stuart E.

2009-01-01

The DEBRIS software predicts the trajectories of debris particles shed by a space-shuttle launch vehicle during ascent, to aid in assessing potential harm to the space-shuttle orbiter and crew. The user specifies the location of release and other initial conditions for a debris particle. DEBRIS tracks the particle within an overset grid system by means of a computational fluid dynamics (CFD) simulation of the local flow field and a ballistic simulation that takes account of the mass of the particle and its aerodynamic properties in the flow field. The computed particle trajectory is stored in a file to be post-processed by other software for viewing and analyzing the trajectory. DEBRIS supplants a prior debris tracking code that took .15 minutes to calculate a single particle trajectory: DEBRIS can calculate 1,000 trajectories in .20 seconds on a desktop computer. Other improvements over the prior code include adaptive time-stepping to ensure accuracy, forcing at least one step per grid cell to ensure resolution of all CFD-resolved flow features, ability to simulate rebound of debris from surfaces, extensive error checking, a builtin suite of test cases, and dynamic allocation of memory.

Single-image diffusion coefficient measurements of proteins in free solution.

PubMed

Zareh, Shannon Kian; DeSantis, Michael C; Kessler, Jonathan M; Li, Je-Luen; Wang, Y M

2012-04-04

Diffusion coefficient measurements are important for many biological and material investigations, such as studies of particle dynamics and kinetics, and size determinations. Among current measurement methods, single particle tracking (SPT) offers the unique ability to simultaneously obtain location and diffusion information about a molecule while using only femtomoles of sample. However, the temporal resolution of SPT is limited to seconds for single-color-labeled samples. By directly imaging three-dimensional diffusing fluorescent proteins and studying the widths of their intensity profiles, we were able to determine the proteins' diffusion coefficients using single protein images of submillisecond exposure times. This simple method improves the temporal resolution of diffusion coefficient measurements to submilliseconds, and can be readily applied to a range of particle sizes in SPT investigations and applications in which diffusion coefficient measurements are needed, such as reaction kinetics and particle size determinations. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Brownian motion of arbitrarily shaped particles in two dimensions.

PubMed

Chakrabarty, Ayan; Konya, Andrew; Wang, Feng; Selinger, Jonathan V; Sun, Kai; Wei, Qi-Huo

2014-11-25

We implement microfabricated boomerang particles with unequal arm lengths as a model for nonsymmetric particles and study their Brownian motion in a quasi-two-dimensional geometry by using high-precision single-particle motion tracking. We show that because of the coupling between translation and rotation, the mean squared displacements of a single asymmetric boomerang particle exhibit a nonlinear crossover from short-time faster to long-time slower diffusion, and the mean displacements for fixed initial orientation are nonzero and saturate out at long times. The measured anisotropic diffusion coefficients versus the tracking point position indicate that there exists one unique point, i.e., the center of hydrodynamic stress (CoH), at which all coupled diffusion coefficients vanish. This implies that in contrast to motion in three dimensions where the CoH exists only for high-symmetry particles, the CoH always exists for Brownian motion in two dimensions. We develop an analytical model based on Langevin theory to explain the experimental results and show that among the six anisotropic diffusion coefficients only five are independent because the translation-translation coupling originates from the translation-rotation coupling. Finally, we classify the behavior of two-dimensional Brownian motion of arbitrarily shaped particles into four groups based on the particle shape symmetry group and discussed potential applications of the CoH in simplifying understanding of the circular motions of microswimmers.

Dual-modality single particle orientation and rotational tracking of intracellular transport of nanocargos.

PubMed

Sun, Wei; Gu, Yan; Wang, Gufeng; Fang, Ning

2012-01-17

The single particle orientation and rotational tracking (SPORT) technique was introduced recently to follow the rotational motion of plasmonic gold nanorod under a differential interference contrast (DIC) microscope. In biological studies, however, cellular activities usually involve a multiplicity of molecules; thus, tracking the motion of a single molecule/object is insufficient. Fluorescence-based techniques have long been used to follow the spatial and temporal distributions of biomolecules of interest thanks to the availability of multiplexing fluorescent probes. To know the type and number of molecules and the timing of their involvement in a biological process under investigation by SPORT, we constructed a dual-modality DIC/fluorescence microscope to simultaneously image fluorescently tagged biomolecules and plasmonic nanoprobes in living cells. With the dual-modality SPORT technique, the microtubule-based intracellular transport can be unambiguously identified while the dynamic orientation of nanometer-sized cargos can be monitored at video rate. Furthermore, the active transport on the microtubule can be easily separated from the diffusion before the nanocargo docks on the microtubule or after it undocks from the microtubule. The potential of dual-modality SPORT is demonstrated for shedding new light on unresolved questions in intracellular transport.

Fluorescent image tracking velocimeter

DOEpatents

Shaffer, Franklin D.

1994-01-01

A multiple-exposure fluorescent image tracking velocimeter (FITV) detects and measures the motion (trajectory, direction and velocity) of small particles close to light scattering surfaces. The small particles may follow the motion of a carrier medium such as a liquid, gas or multi-phase mixture, allowing the motion of the carrier medium to be observed, measured and recorded. The main components of the FITV include: (1) fluorescent particles; (2) a pulsed fluorescent excitation laser source; (3) an imaging camera; and (4) an image analyzer. FITV uses fluorescing particles excited by visible laser light to enhance particle image detectability near light scattering surfaces. The excitation laser light is filtered out before reaching the imaging camera allowing the fluoresced wavelengths emitted by the particles to be detected and recorded by the camera. FITV employs multiple exposures of a single camera image by pulsing the excitation laser light for producing a series of images of each particle along its trajectory. The time-lapsed image may be used to determine trajectory and velocity and the exposures may be coded to derive directional information.

NIR-emitting molecular-based nanoparticles as new two-photon absorbing nanotools for single particle tracking

NASA Astrophysics Data System (ADS)

Daniel, J.; Godin, A. G.; Clermont, G.; Lounis, B.; Cognet, L.; Blanchard-Desce, M.

2015-07-01

In order to provide a green alternative to QDs for bioimaging purposes and aiming at designing bright nanoparticles combining both large one- and two-photon brightness, a bottom-up route based on the molecular engineering of dedicated red to NIR emitting dyes that spontaneously form fluorescent organic nanoparticles (FONs) has been implemented. These fully organic nanoparticles built from original quadrupolar dyes are prepared using a simple, expeditious and green protocol that yield very small molecular-based nanoparticles (radius ~ 7 nm) suspension in water showing a nice NIR emission (λem=710 nm). These FONs typically have absorption coefficient more than two orders larger than popular NIR-emitting dyes (such as Alexa Fluor 700, Cy5.5 ….) and much larger Stokes shift values (i.e. up to over 5500 cm-1). They also show very large two-photon absorption response in the 800-1050 nm region (up to about 106 GM) of major promise for two-photon excited fluorescence microscopy. Thanks to their brightness and enhanced photostability, these FONs could be imaged as isolated nanoparticles and tracked using wide-field imaging. As such, thanks to their size and composition (absence of heavy metals), they represent highly promising alternatives to NIR-emitting QDs for use in bioimaging and single particle tracking applications. Moreover, efficient FONs coating was achieved by using a polymeric additive built from a long hydrophobic (PPO) and a short hydrophilic (PEO) segment and having a cationic head group able to interact with the highly negative surface of FONs. This electrostatically-driven interaction promotes both photoluminescence and two-photon absorption enhancement leading to an increase of two-photon brightness of about one order of magnitude. This opens the way to wide-field single particle tracking under two-photon excitation

Triple tracks in CR-39 as the result of Pd-D Co-deposition: evidence of energetic neutrons.

PubMed

Mosier-Boss, Pamela A; Szpak, Stanislaw; Gordon, Frank E; Forsley, Lawrence P G

2009-01-01

Since the announcement by Fleischmann and Pons that the excess enthalpy generated in the negatively polarized Pd-D-D(2)O system was attributable to nuclear reactions occurring inside the Pd lattice, there have been reports of other manifestations of nuclear activities in this system. In particular, there have been reports of tritium and helium-4 production; emission of energetic particles, gamma or X-rays, and neutrons; as well as the transmutation of elements. In this communication, the results of Pd-D co-deposition experiments conducted with the cathode in close contact with CR-39, a solid-state nuclear etch detector, are reported. Among the solitary tracks due to individual energetic particles, triple tracks are observed. Microscopic examination of the bottom of the triple track pit shows that the three lobes of the track are splitting apart from a center point. The presence of three alpha-particle tracks outgoing from a single point is diagnostic of the (12)C(n,n')3alpha carbon breakup reaction and suggests that DT reactions that produce > or = 9.6 MeV neutrons are occurring inside the Pd lattice. To our knowledge, this is the first report of the production of energetic (> or = 9.6 MeV) neutrons in the Pd-D system.

Classification and Segmentation of Nanoparticle Diffusion Trajectories in Cellular Micro Environments

PubMed Central

Kroll, Alexandra; Haramagatti, Chandrashekara R.; Lipinski, Hans-Gerd; Wiemann, Martin

2017-01-01

Darkfield and confocal laser scanning microscopy both allow for a simultaneous observation of live cells and single nanoparticles. Accordingly, a characterization of nanoparticle uptake and intracellular mobility appears possible within living cells. Single particle tracking allows to measure the size of a diffusing particle close to a cell. However, within the more complex system of a cell’s cytoplasm normal, confined or anomalous diffusion together with directed motion may occur. In this work we present a method to automatically classify and segment single trajectories into their respective motion types. Single trajectories were found to contain more than one motion type. We have trained a random forest with 9 different features. The average error over all motion types for synthetic trajectories was 7.2%. The software was successfully applied to trajectories of positive controls for normal- and constrained diffusion. Trajectories captured by nanoparticle tracking analysis served as positive control for normal diffusion. Nanoparticles inserted into a diblock copolymer membrane was used to generate constrained diffusion. Finally we segmented trajectories of diffusing (nano-)particles in V79 cells captured with both darkfield- and confocal laser scanning microscopy. The software called “TraJClassifier” is freely available as ImageJ/Fiji plugin via https://git.io/v6uz2. PMID:28107406

Single-particle tracking of quantum dot-conjugated prion proteins inside yeast cells

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

Tsuji, Toshikazu; Kawai-Noma, Shigeko; Pack, Chan-Gi

2011-02-25

Research highlights: {yields} We develop a method to track a quantum dot-conjugated protein in yeast cells. {yields} We incorporate the conjugated quantum dot proteins into yeast spheroplasts. {yields} We track the motions by conventional or 3D tracking microscopy. -- Abstract: Yeast is a model eukaryote with a variety of biological resources. Here we developed a method to track a quantum dot (QD)-conjugated protein in the budding yeast Saccharomyces cerevisiae. We chemically conjugated QDs with the yeast prion Sup35, incorporated them into yeast spheroplasts, and tracked the motions by conventional two-dimensional or three-dimensional tracking microscopy. The method paves the way towardmore » the individual tracking of proteins of interest inside living yeast cells.« less

Induction of single- and double-strand breaks in plasmid DNA by monoenergetic alpha-particles with energies below the Bragg-maximum.

PubMed

Scholz, V; Weidner, J; Köhnlein, W; Frekers, D; Wörtche, H J

1997-01-01

The yield of single-strand breaks (ssb) and double-strand breaks (dsb) produced by alpha-particles at the end of their track in DNA-films was determined experimentally. Helium nuclei were accelerated to 600 keV in the 400 kV ion accelerator and scattered at a carbon target. The elastically scattered alpha-particles with energies of 344 keV and 485 keV were used to irradiate supercircular plasmid DNA in vacuo. For the dosimetry of the alpha-particles a surface barrier detector was used and the energy distribution of the alpha-particles determined. The energy loss of the particles in the DNA-layer was calculated. DNA samples were separated into the three conformational isomers using agarose gel electrophoresis. After fluorochromation the number of ssb and dsb per plasmid DNA molecule was established from the band intensities assuming the validity of Poisson statistics. Linear dose effect correlations were found for ssb and dsb per plasmid molecule. In the case of 344 keV-alpha-particles the yield of dsb was (8.6 +/- 0.9) x 10(-11) breaks/Gy x dalton. The ratio of ssb/dsb was 0.5 +/- 0.2. This is at least a factor of six larger than the ratio found in experiments with higher energy alpha-particles and from model calculations. Similar experiments with protons yielded a relative biological effectiveness (rbe) value of 2.8 for the induction of double-strand breaks by track end alpha-particles.

A method to track rotational motion for use in single-molecule biophysics.

PubMed

Lipfert, Jan; Kerssemakers, Jacob J W; Rojer, Maylon; Dekker, Nynke H

2011-10-01

The double helical nature of DNA links many cellular processes such as DNA replication, transcription, and repair to rotational motion and the accumulation of torsional strain. Magnetic tweezers (MTs) are a single-molecule technique that enables the application of precisely calibrated stretching forces to nucleic acid tethers and to control their rotational motion. However, conventional magnetic tweezers do not directly monitor rotation or measure torque. Here, we describe a method to directly measure rotational motion of particles in MT. The method relies on attaching small, non-magnetic beads to the magnetic beads to act as fiducial markers for rotational tracking. CCD images of the beads are analyzed with a tracking algorithm specifically designed to minimize crosstalk between translational and rotational motion: first, the in-plane center position of the magnetic bead is determined with a kernel-based tracker, while subsequently the height and rotation angle of the bead are determined via correlation-based algorithms. Evaluation of the tracking algorithm using both simulated images and recorded images of surface-immobilized beads demonstrates a rotational resolution of 0.1°, while maintaining a translational resolution of 1-2 nm. Example traces of the rotational fluctuations exhibited by DNA-tethered beads confined in magnetic potentials of varying stiffness demonstrate the robustness of the method and the potential for simultaneous tracking of multiple beads. Our rotation tracking algorithm enables the extension of MTs to magnetic torque tweezers (MTT) to directly measure the torque in single molecules. In addition, we envision uses of the algorithm in a range of biophysical measurements, including further extensions of MT, tethered particle motion, and optical trapping measurements.

Deep and high-resolution three-dimensional tracking of single particles using nonlinear and multiplexed illumination

NASA Astrophysics Data System (ADS)

Perillo, Evan P.; Liu, Yen-Liang; Huynh, Khang; Liu, Cong; Chou, Chao-Kai; Hung, Mien-Chie; Yeh, Hsin-Chih; Dunn, Andrew K.

2015-07-01

Molecular trafficking within cells, tissues and engineered three-dimensional multicellular models is critical to the understanding of the development and treatment of various diseases including cancer. However, current tracking methods are either confined to two dimensions or limited to an interrogation depth of ~15 μm. Here we present a three-dimensional tracking method capable of quantifying rapid molecular transport dynamics in highly scattering environments at depths up to 200 μm. The system has a response time of 1 ms with a temporal resolution down to 50 μs in high signal-to-noise conditions, and a spatial localization precision as good as 35 nm. Built on spatiotemporally multiplexed two-photon excitation, this approach requires only one detector for three-dimensional particle tracking and allows for two-photon, multicolour imaging. Here we demonstrate three-dimensional tracking of epidermal growth factor receptor complexes at a depth of ~100 μm in tumour spheroids.

Characterization of the energy resolution and the tracking capabilities of a hybrid pixel detector with CdTe-sensor layer for a possible use in a neutrinoless double beta decay experiment

NASA Astrophysics Data System (ADS)

Filipenko, Mykhaylo; Gleixner, Thomas; Anton, Gisela; Durst, Jürgen; Michel, Thilo

2013-04-01

Many different experiments are being developed to explore the existence of the neutrinoless double beta decay (0 νββ) since it would imply fundamental consequences for particle physics. In this work we present results on the evaluation of Timepix detectors with cadmium-telluride sensor material to search for 0 νββ in 116Cd. This work was carried out with the COBRA collaboration and the Medipix collaboration. Due to the relatively small pixel dimension of 110×110×1000 μm3 the energy deposited by particles typically extends over several detector pixels leading to a track in the pixel matrix. We investigated the separation power regarding different event-types like α-particles, atmospheric muons, single electrons and electron-positron pairs produced at a single vertex. We achieved excellent classification power for α-particles and muons. In addition, we achieved good separation power between single electron and electron-positron pair production events. These separation abilities indicate a very good background reduction for the 0 νββ search. Further, in order to distinguish between 2 νββ and 0 νββ, the energy resolution is of particular importance. We carried out simulations which demonstrate that an energy resolution of 0.43 % is achievable at the Q-value for 0 νββ of 116Cd at 2.814 MeV. We measured an energy resolution of 1.6 % at a nominal energy of 1589 keV for electron-positron tracks which is about two times worse that predicted by our simulations. This deviation is probably due to the problem of detector calibration at energies above 122 keV which is discussed in this paper as well.

Co-localization of fluorescent labeled lipid nanoparticles with specifically tagged subcellular compartments by single particle tracking at low nanoparticle to cell ratios.

PubMed

Tiffany, Matthew; Szoka, Francis C

2016-11-01

We utilized quantitative high-resolution single particle tracking to study the internalization and endosomal sorting of lipid nanoparticles (LNPs) by HeLa cells in vitro to gain a better understanding of how cells process LNPs that are used for siRNA delivery. We compared the trafficking of three formulations that have been demonstrated to deliver siRNA into cells. They were composed of either a tritratable anionic lipid, formulation of cholesterol hemisuccinate (CHEMS), or a titratatable cationic lipid formulation of 1,2-dilinoleyloxy-3-dimethylaminopropane (DLinDMA) or a non-titratable cationic formulation lipid formulation of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). They also contained either a substantial percentage of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) or cholesterol and 5 mole percent 1,2-dimyristoyl-sn-glycerol-[methoxy(polyethylene glycol)-2000 (PEG-DMG). We optically measured the endosomal pH experienced by individual LNPs, observed the internalization pathways used and tracked the particles as they co-localized with fluorescent protein tags on compartment-specific proteins, during endosomal sorting to the lysosome. The data revealed significant differences in the accumulation in subcellular compartments among the three formulations, which help to explain the observed effects LNP composition exerts on in vitro delivery efficiency.

PIV-Based Examination of Dynamic Stall on an Oscillating Airfoil

DTIC Science & Technology

2008-03-01

vectors at a very large number of points simultaneously” ( Adrian R. , 2005). PIV is accomplished by tracking indiscriminate particles in the flow at...Particle image velocimetry (PIV) theory has been discussed, developed, and used for over 20 years ( Adrian R. , 2005) as a tool for researchers to...stream flow. It is important to note that single image pair solution can have anomalies (i.e. due to turbulence, blooming , particle debris) that

Single and multiple object tracking using log-euclidean Riemannian subspace and block-division appearance model.

PubMed

Hu, Weiming; Li, Xi; Luo, Wenhan; Zhang, Xiaoqin; Maybank, Stephen; Zhang, Zhongfei

2012-12-01

Object appearance modeling is crucial for tracking objects, especially in videos captured by nonstationary cameras and for reasoning about occlusions between multiple moving objects. Based on the log-euclidean Riemannian metric on symmetric positive definite matrices, we propose an incremental log-euclidean Riemannian subspace learning algorithm in which covariance matrices of image features are mapped into a vector space with the log-euclidean Riemannian metric. Based on the subspace learning algorithm, we develop a log-euclidean block-division appearance model which captures both the global and local spatial layout information about object appearances. Single object tracking and multi-object tracking with occlusion reasoning are then achieved by particle filtering-based Bayesian state inference. During tracking, incremental updating of the log-euclidean block-division appearance model captures changes in object appearance. For multi-object tracking, the appearance models of the objects can be updated even in the presence of occlusions. Experimental results demonstrate that the proposed tracking algorithm obtains more accurate results than six state-of-the-art tracking algorithms.

Quantum dot-loaded monofunctionalized DNA icosahedra for single-particle tracking of endocytic pathways.

PubMed

Bhatia, Dhiraj; Arumugam, Senthil; Nasilowski, Michel; Joshi, Himanshu; Wunder, Christian; Chambon, Valérie; Prakash, Ved; Grazon, Chloé; Nadal, Brice; Maiti, Prabal K; Johannes, Ludger; Dubertret, Benoit; Krishnan, Yamuna

2016-12-01

Functionalization of quantum dots (QDs) with a single biomolecular tag using traditional approaches in bulk solution has met with limited success. DNA polyhedra consist of an internal void bounded by a well-defined three-dimensional structured surface. The void can house cargo and the surface can be functionalized with stoichiometric and spatial precision. Here, we show that monofunctionalized QDs can be realized by encapsulating QDs inside DNA icosahedra and functionalizing the DNA shell with an endocytic ligand. We deployed the DNA-encapsulated QDs for real-time imaging of three different endocytic ligands-folic acid, galectin-3 (Gal3) and the Shiga toxin B-subunit (STxB). Single-particle tracking of Gal3- or STxB-functionalized QD-loaded DNA icosahedra allows us to monitor compartmental dynamics along endocytic pathways. These DNA-encapsulated QDs, which bear a unique stoichiometry of endocytic ligands, represent a new class of molecular probes for quantitative imaging of endocytic receptor dynamics.

Classification of nanoparticle diffusion processes in vital cells by a multifeature random forests approach: application to simulated data, darkfield, and confocal laser scanning microscopy

NASA Astrophysics Data System (ADS)

Wagner, Thorsten; Kroll, Alexandra; Wiemann, Martin; Lipinski, Hans-Gerd

2016-04-01

Darkfield and confocal laser scanning microscopy both allow for a simultaneous observation of live cells and single nanoparticles. Accordingly, a characterization of nanoparticle uptake and intracellular mobility appears possible within living cells. Single particle tracking makes it possible to characterize the particle and the surrounding cell. In case of free diffusion, the mean squared displacement for each trajectory of a nanoparticle can be measured which allows computing the corresponding diffusion coefficient and, if desired, converting it into the hydrodynamic diameter using the Stokes-Einstein equation and the viscosity of the fluid. However, within the more complex system of a cell's cytoplasm unrestrained diffusion is scarce and several other types of movements may occur. Thus, confined or anomalous diffusion (e.g. diffusion in porous media), active transport, and combinations thereof were described by several authors. To distinguish between these types of particle movement we developed an appropriate classification method, and simulated three types of particle motion in a 2D plane using a Monte Carlo approach: (1) normal diffusion, using random direction and step-length, (2) subdiffusion, using confinements like a reflective boundary with defined radius or reflective objects in the closer vicinity, and (3) superdiffusion, using a directed flow added to the normal diffusion. To simulate subdiffusion we devised a new method based on tracks of different length combined with equally probable obstacle interaction. Next we estimated the fractal dimension, elongation and the ratio of long-time / short-time diffusion coefficients. These features were used to train a random forests classification algorithm. The accuracy for simulated trajectories with 180 steps was 97% (95%-CI: 0.9481-0.9884). The balanced accuracy was 94%, 99% and 98% for normal-, sub- and superdiffusion, respectively. Nanoparticle tracking analysis was used with 100 nm polystyrene particles to get trajectories for normal diffusion. As a next step we identified diffusion types of nanoparticles in vital cells and incubated V79 fibroblasts with 50 nm gold nanoparticles, which appeared as intensely bright objects due to their surface plasmon resonance. The movement of particles in both the extracellular and intracellular space was observed by dark field and confocal laser scanning microscopy. After reducing background noise from the video it became possible to identify individual particle spots by a maximum detection algorithm and trace them using the robust single-particle tracking algorithm proposed by Jaqaman, which is able to handle motion heterogeneity and particle disappearance. The particle trajectories inside cells indicated active transport (superdiffusion) as well as subdiffusion. Eventually, the random forest classification algorithm, after being trained by the above simulations, successfully classified the trajectories observed in live cells.

Experimental Studies of the Brownian Diffusion of Boomerang Colloidal Particle in a Confined Geometry

NASA Astrophysics Data System (ADS)

Chakrabarty, Ayan; Wang, Feng; Joshi, Bhuwan; Wei, Qi-Huo

2011-03-01

Recent studies shows that the boomerang shaped molecules can form various kinds of liquid crystalline phases. One debated topic related to boomerang molecules is the existence of biaxial nematic liquid crystalline phase. Developing and optical microscopic studies of colloidal systems of boomerang particles would allow us to gain better understanding of orientation ordering and dynamics at ``single molecule'' level. Here we report the fabrication and experimental studies of the Brownian motion of individual boomerang colloidal particles confined between two glass plates. We used dark-field optical microscopy to directly visualize the Brownian motion of the single colloidal particles in a quasi two dimensional geometry. An EMCCD was used to capture the motion in real time. An indigenously developed imaging processing algorithm based on MatLab program was used to precisely track the position and orientation of the particles with sub-pixel accuracy. The experimental finding of the Brownian diffusion of a single boomerang colloidal particle will be discussed.

Comparative assessment of pressure field reconstructions from particle image velocimetry measurements and Lagrangian particle tracking

NASA Astrophysics Data System (ADS)

van Gent, P. L.; Michaelis, D.; van Oudheusden, B. W.; Weiss, P.-É.; de Kat, R.; Laskari, A.; Jeon, Y. J.; David, L.; Schanz, D.; Huhn, F.; Gesemann, S.; Novara, M.; McPhaden, C.; Neeteson, N. J.; Rival, D. E.; Schneiders, J. F. G.; Schrijer, F. F. J.

2017-04-01

A test case for pressure field reconstruction from particle image velocimetry (PIV) and Lagrangian particle tracking (LPT) has been developed by constructing a simulated experiment from a zonal detached eddy simulation for an axisymmetric base flow at Mach 0.7. The test case comprises sequences of four subsequent particle images (representing multi-pulse data) as well as continuous time-resolved data which can realistically only be obtained for low-speed flows. Particle images were processed using tomographic PIV processing as well as the LPT algorithm `Shake-The-Box' (STB). Multiple pressure field reconstruction techniques have subsequently been applied to the PIV results (Eulerian approach, iterative least-square pseudo-tracking, Taylor's hypothesis approach, and instantaneous Vortex-in-Cell) and LPT results (FlowFit, Vortex-in-Cell-plus, Voronoi-based pressure evaluation, and iterative least-square pseudo-tracking). All methods were able to reconstruct the main features of the instantaneous pressure fields, including methods that reconstruct pressure from a single PIV velocity snapshot. Highly accurate reconstructed pressure fields could be obtained using LPT approaches in combination with more advanced techniques. In general, the use of longer series of time-resolved input data, when available, allows more accurate pressure field reconstruction. Noise in the input data typically reduces the accuracy of the reconstructed pressure fields, but none of the techniques proved to be critically sensitive to the amount of noise added in the present test case.

Comparison of three-dimensional particle tracking and sizing using plenoptic imaging and digital in-line holography

DOE PAGES

Hall, Elise M.; Thurow, Brian S.; Guildenbecher, Daniel R.

2016-08-08

Digital in-line holography (DIH) and plenoptic photography are two techniques for single-shot, volumetric measurement of 3D particle fields. Here we present a comparison of the two methods by applying plenoptic imaging to experimental configurations that have been previously investigated with DIH. These experiments include the tracking of secondary droplets from the impact of a water drop on a thin film of water and tracking of pellets from a shotgun. Both plenoptic imaging and DIH successfully quantify the 3D nature of these particle fields. Furthermore, this includes measurement of the 3D particle position, individual particle sizes, and three-component velocity vectors. Formore » the initial processing methods presented here, both techniques give out-of-plane positional accuracy of approximately 1–2 particle diameters. For a fixed image sensor, digital holography achieves higher effective in-plane spatial resolutions. However, collimated and coherent illumination makes holography susceptible to image distortion through index of refraction gradients, as demonstrated in the shotgun experiments. In contrast, plenoptic imaging allows for a simpler experimental configuration and, due to the use of diffuse, white-light illumination, plenoptic imaging is less susceptible to image distortion in the shotgun experiments.« less

Timepix Device Efficiency for Pattern Recognition of Tracks Generated by Ionizing Radiation

NASA Astrophysics Data System (ADS)

Leroy, Claude; Asbah, Nedaa; Gagnon, Louis-Guilaume; Larochelle, Jean-Simon; Pospisil, Stanislav; Soueid, Paul

2014-06-01

A hybrid silicon pixelated TIMEPIX detector (256 × 256 pixels with 55 μm pitch) operated in Time Over Threshold (TOT) mode was exposed to radioactive sources (241Am, 106Ru, 137Cs), protons and alpha-particles after Rutherford Backscattering on a thin gold foil of protons and alpha-particles beams delivered by the Tandem Accelerator of Montreal University. Measurements were also performed with different mixed radiation fields of heavy charged particles (protons and alpha-particles), photons and electrons produced by simultaneous exposure of TIMEPIX to the radioactive sources and to protons beams on top of the radioactive sources. All measurements were performed in vacuum. The TOT mode of operation has allowed the direct measurement of the energy deposited in each pixel. The efficiency of track recognition with this device was tested by comparing the experimental activities (determined from number of tracks measurements) of the radioactive sources with their expected activities. The efficiency of track recognition of incident protons and alpha-particles of different energies as a function of the incidence angle was measured. The operation of TIMEPIX in TOT mode has allowed a 3D mapping of the charge sharing effect in the whole volume of the silicon sensor. The effect of the bias voltage on charge sharing was investigated as the level of charge sharing is related to the local profile of the electric field in the sensor. The results of the present measurements demonstrate the TIMEPIX capability of differentiating between different types of particles species from mixed radiation fields and measuring their energy deposition. Single track analysis gives a good precision (significantly better than the 55 μm size of one detector pixel) on the coordinates of the impact point of protons interacting in the TIMEPIX silicon layer.

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

Chen, Kuangcai; Lin, Chia -Cheng; Vela, Javier

In this study, three-layer core–shell plasmonic nanorods (Au/Ag/SiO 2–NRs), consisting of a gold nanorod core, a thin silver shell, and a thin silica layer, were synthesized and used as optical imaging probes under a differential interference contrast microscope for single particle orientation and rotational tracking. The localized surface plasmon resonance modes were enhanced upon the addition of the silver shell, and the anisotropic optical properties of gold nanorods were maintained. The silica coating enables surface functionalization with silane coupling agents and provides enhanced stability and biocompatibility. Taking advantage of the longitudinal LSPR enhancement, the orientation and rotational information of themore » hybrid nanorods on synthetic lipid bilayers and on live cell membranes were obtained with millisecond temporal resolution using a scientific complementary metal-oxide-semiconductor camera. The results demonstrate that the as-synthesized hybrid nanorods are promising imaging probes with improved sensitivity and good biocompatibility for single plasmonic particle tracking experiments in biological systems.« less

Counting polymers moving through a single ion channel

NASA Astrophysics Data System (ADS)

Bezrukov, Sergey M.; Vodyanoy, Igor; Parsegian, V. Adrian

1994-07-01

THE change in conductance of a small electrolyte-filled capillary owing to the passage of sub-micrometre-sized particles has long been used for particle counting and sizing. A commercial device for such measurements, the Coulter counter, is able to detect particles of sizes down to several tenths of a micrometre1-3. Nuclepore technology (in which pores are etched particle tracks) has extended the lower limit of size detection to 60-nm particles by using a capillary of diameter 0.45 μm (ref. 4). Here we show that natural channel-forming peptides incorporated into a bilayer lipid membrane can be used to detect the passage of single molecules with gyration radii as small as 5-15 Å. From our experiments with alamethicin pores we infer both the average number and the diffusion coefficients of poly(ethylene glycol) molecules in the pore. Our approach provides a means of observing the statistics and mechanics of flexible polymers moving within the confines of precisely defined single-molecule structures.

Lipid diffusion in the distal and proximal leaflets of supported lipid bilayer membranes studied by single particle tracking

NASA Astrophysics Data System (ADS)

Schoch, Rafael L.; Barel, Itay; Brown, Frank L. H.; Haran, Gilad

2018-03-01

Supported lipid bilayers (SLBs) have been studied extensively as simple but powerful models for cellular membranes. Yet, potential differences in the dynamics of the two leaflets of a SLB remain poorly understood. Here, using single particle tracking, we obtain a detailed picture of bilayer dynamics. We observe two clearly separate diffusing populations, fast and slow, that we associate with motion in the distal and proximal leaflets of the SLB, respectively, based on fluorescence quenching experiments. We estimate diffusion coefficients using standard techniques as well as a new method based on the blur of images due to motion. Fitting the observed diffusion coefficients to a two-leaflet membrane hydrodynamic model allows for the simultaneous determination of the intermonolayer friction coefficient and the substrate-membrane friction coefficient, without any prior assumptions on the strengths of the relevant interactions. Remarkably, our calculations suggest that the viscosity of the interfacial water confined between the membrane and the substrate is elevated by ˜104 as compared to bulk water. Using hidden Markov model analysis, we then obtain insight into the transbilayer movement of lipids. We find that lipid flip-flop dynamics are very fast, with half times in the range of seconds. Importantly, we find little evidence for membrane defect mediated lipid flip-flop for SLBs at temperatures well above the solid-to-liquid transition, though defects seem to be involved when the SLBs are cooled down. Our work thus shows that the combination of single particle tracking and advanced hydrodynamic modeling provides a powerful means to obtain insight into membrane dynamics.

Neutron Radiography of Fluid Flow for Geothermal Energy Research

NASA Astrophysics Data System (ADS)

Bingham, P.; Polsky, Y.; Anovitz, L.; Carmichael, J.; Bilheux, H.; Jacobsen, D.; Hussey, D.

Enhanced geothermal systems seek to expand the potential for geothermal energy by engineering heat exchange systems within the earth. A neutron radiography imaging method has been developed for the study of fluid flow through rock under environmental conditions found in enhanced geothermal energy systems. For this method, a pressure vessel suitable for neutron radiography was designed and fabricated, modifications to imaging instrument setups were tested, multiple contrast agents were tested, and algorithms developed for tracking of flow. The method has shown success for tracking of single phase flow through a manufactured crack in a 3.81 cm (1.5 inch) diameter core within a pressure vessel capable of confinement up to 69 MPa (10,000 psi) using a particle tracking approach with bubbles of fluorocarbon-based fluid as the ;particles; and imaging with 10 ms exposures.

Imaging samples in silica aerogel using an experimental point spread function.

PubMed

White, Amanda J; Ebel, Denton S

2015-02-01

Light microscopy is a powerful tool that allows for many types of samples to be examined in a rapid, easy, and nondestructive manner. Subsequent image analysis, however, is compromised by distortion of signal by instrument optics. Deconvolution of images prior to analysis allows for the recovery of lost information by procedures that utilize either a theoretically or experimentally calculated point spread function (PSF). Using a laser scanning confocal microscope (LSCM), we have imaged whole impact tracks of comet particles captured in silica aerogel, a low density, porous SiO2 solid, by the NASA Stardust mission. In order to understand the dynamical interactions between the particles and the aerogel, precise grain location and track volume measurement are required. We report a method for measuring an experimental PSF suitable for three-dimensional deconvolution of imaged particles in aerogel. Using fluorescent beads manufactured into Stardust flight-grade aerogel, we have applied a deconvolution technique standard in the biological sciences to confocal images of whole Stardust tracks. The incorporation of an experimentally measured PSF allows for better quantitative measurements of the size and location of single grains in aerogel and more accurate measurements of track morphology.

A quantitative comparison of single-dye tracking analysis tools using Monte Carlo simulations.

PubMed

Weimann, Laura; Ganzinger, Kristina A; McColl, James; Irvine, Kate L; Davis, Simon J; Gay, Nicholas J; Bryant, Clare E; Klenerman, David

2013-01-01

Single-particle tracking (SPT) is widely used to study processes from membrane receptor organization to the dynamics of RNAs in living cells. While single-dye labeling strategies have the benefit of being minimally invasive, this comes at the expense of data quality; typically a data set of short trajectories is obtained and analyzed by means of the mean square displacements (MSD) or the distribution of the particles' displacements in a set time interval (jump distance, JD). To evaluate the applicability of both approaches, a quantitative comparison of both methods under typically encountered experimental conditions is necessary. Here we use Monte Carlo simulations to systematically compare the accuracy of diffusion coefficients (D-values) obtained for three cases: one population of diffusing species, two populations with different D-values, and a population switching between two D-values. For the first case we find that the MSD gives more or equally accurate results than the JD analysis (relative errors of D-values <6%). If two diffusing species are present or a particle undergoes a motion change, the JD analysis successfully distinguishes both species (relative error <5%). Finally we apply the JD analysis to investigate the motion of endogenous LPS receptors in live macrophages before and after treatment with methyl-β-cyclodextrin and latrunculin B.

Sequential bearings-only-tracking initiation with particle filtering method.

PubMed

Liu, Bin; Hao, Chengpeng

2013-01-01

The tracking initiation problem is examined in the context of autonomous bearings-only-tracking (BOT) of a single appearing/disappearing target in the presence of clutter measurements. In general, this problem suffers from a combinatorial explosion in the number of potential tracks resulted from the uncertainty in the linkage between the target and the measurement (a.k.a the data association problem). In addition, the nonlinear measurements lead to a non-Gaussian posterior probability density function (pdf) in the optimal Bayesian sequential estimation framework. The consequence of this nonlinear/non-Gaussian context is the absence of a closed-form solution. This paper models the linkage uncertainty and the nonlinear/non-Gaussian estimation problem jointly with solid Bayesian formalism. A particle filtering (PF) algorithm is derived for estimating the model's parameters in a sequential manner. Numerical results show that the proposed solution provides a significant benefit over the most commonly used methods, IPDA and IMMPDA. The posterior Cramér-Rao bounds are also involved for performance evaluation.

Robust and highly performant ring detection algorithm for 3d particle tracking using 2d microscope imaging

NASA Astrophysics Data System (ADS)

Afik, Eldad

2015-09-01

Three-dimensional particle tracking is an essential tool in studying dynamics under the microscope, namely, fluid dynamics in microfluidic devices, bacteria taxis, cellular trafficking. The 3d position can be determined using 2d imaging alone by measuring the diffraction rings generated by an out-of-focus fluorescent particle, imaged on a single camera. Here I present a ring detection algorithm exhibiting a high detection rate, which is robust to the challenges arising from ring occlusion, inclusions and overlaps, and allows resolving particles even when near to each other. It is capable of real time analysis thanks to its high performance and low memory footprint. The proposed algorithm, an offspring of the circle Hough transform, addresses the need to efficiently trace the trajectories of many particles concurrently, when their number in not necessarily fixed, by solving a classification problem, and overcomes the challenges of finding local maxima in the complex parameter space which results from ring clusters and noise. Several algorithmic concepts introduced here can be advantageous in other cases, particularly when dealing with noisy and sparse data. The implementation is based on open-source and cross-platform software packages only, making it easy to distribute and modify. It is implemented in a microfluidic experiment allowing real-time multi-particle tracking at 70 Hz, achieving a detection rate which exceeds 94% and only 1% false-detection.

Magnetophoretic transistors in a tri-axial magnetic field.

PubMed

Abedini-Nassab, Roozbeh; Joh, Daniel Y; Albarghouthi, Faris; Chilkoti, Ashutosh; Murdoch, David M; Yellen, Benjamin B

2016-10-18

The ability to direct and sort individual biological and non-biological particles into spatially addressable locations is fundamentally important to the emerging field of single cell biology. Towards this goal, we demonstrate a new class of magnetophoretic transistors, which can switch single magnetically labeled cells and magnetic beads between different paths in a microfluidic chamber. Compared with prior work on magnetophoretic transistors driven by a two-dimensional in-plane rotating field, the addition of a vertical magnetic field bias provides significant advantages in preventing the formation of particle clumps and in better replicating the operating principles of circuits in general. However, the three-dimensional driving field requires a complete redesign of the magnetic track geometry and switching electrodes. We have solved this problem by developing several types of transistor geometries which can switch particles between two different tracks by either presenting a local energy barrier or by repelling magnetic objects away from a given track, hereby denoted as "barrier" and "repulsion" transistors, respectively. For both types of transistors, we observe complete switching of magnetic objects with currents of ∼40 mA, which is consistent over a range of particle sizes (8-15 μm). The switching efficiency was also tested at various magnetic field strengths (50-90 Oe) and driving frequencies (0.1-0.6 Hz); however, we again found that the device performance only weakly depended on these parameters. These findings support the use of these novel transistor geometries to form circuit architectures in which cells can be placed in defined locations and retrieved on demand.

Interferometric Scattering Microscopy for the Study of Molecular Motors

PubMed Central

Andrecka, J.; Takagi, Y.; Mickolajczyk, K.J.; Lippert, L.G.; Sellers, J.R.; Hancock, W.O.; Goldman, Y.E.; Kukura, P.

2016-01-01

Our understanding of molecular motor function has been greatly improved by the development of imaging modalities, which enable real-time observation of their motion at the single-molecule level. Here, we describe the use of a new method, interferometric scattering microscopy, for the investigation of motor protein dynamics by attaching and tracking the motion of metallic nanoparticle labels as small as 20 nm diameter. Using myosin-5, kinesin-1, and dynein as examples, we describe the basic assays, labeling strategies, and principles of data analysis. Our approach is relevant not only for motor protein dynamics but also provides a general tool for single-particle tracking with high spatiotemporal precision, which overcomes the limitations of single-molecule fluorescence methods. PMID:27793291

Brownian motion studies of viscoelastic colloidal gels by rotational single particle tracking

DOE PAGES

Liang, Mengning; Harder, Ross; Robinson, Ian K.

2014-04-14

Colloidal gels have unique properties due to a complex microstructure which forms into an extended network. Although the bulk properties of colloidal gels have been studied, there has been difficulty correlating those properties with individual colloidal dynamics on the microscale due to the very high viscosity and elasticity of the material. We utilize rotational X-ray tracking (RXT) to investigate the rotational motion of component crystalline colloidal particles in a colloidal gel of alumina and decanoic acid. Our investigation has determined that the high elasticity of the bulk is echoed by a high elasticity experienced by individual colloidal particles themselves butmore » also finds an unexpected high degree of rotational diffusion, indicating a large degree of freedom in the rotational motion of individual colloids even within a tightly bound system.« less

Simulation of the charge migration in DNA under irradiation with heavy ions.

PubMed

Belov, Oleg V; Boyda, Denis L; Plante, Ianik; Shirmovsky, Sergey Eh

2015-01-01

A computer model to simulate the processes of charge injection and migration through DNA after irradiation by a heavy charged particle was developed. The most probable sites of charge injection were obtained by merging spatial models of short DNA sequence and a single 1 GeV/u iron particle track simulated by the code RITRACKS (Relativistic Ion Tracks). Charge migration was simulated by using a quantum-classical nonlinear model of the DNA-charge system. It was found that charge migration depends on the environmental conditions. The oxidative damage in DNA occurring during hole migration was simulated concurrently, which allowed the determination of probable locations of radiation-induced DNA lesions.

Revised Extended Grid Library

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

Martz, Roger L.

The Revised Eolus Grid Library (REGL) is a mesh-tracking library that was developed for use with the MCNP6TM computer code so that (radiation) particles can track on an unstructured mesh. The unstructured mesh is a finite element representation of any geometric solid model created with a state-of-the-art CAE/CAD tool. The mesh-tracking library is written using modern Fortran and programming standards; the library is Fortran 2003 compliant. The library was created with a defined application programmer interface (API) so that it could easily integrate with other particle tracking/transport codes. The library does not handle parallel processing via the message passing interfacemore » (mpi), but has been used successfully where the host code handles the mpi calls. The library is thread-safe and supports the OpenMP paradigm. As a library, all features are available through the API and overall a tight coupling between it and the host code is required. Features of the library are summarized with the following list: Can accommodate first and second order 4, 5, and 6-sided polyhedra; any combination of element types may appear in a single geometry model; parts may not contain tetrahedra mixed with other element types; pentahedra and hexahedra can be together in the same part; robust handling of overlaps and gaps; tracks element-to-element to produce path length results at the element level; finds element numbers for a given mesh location; finds intersection points on element faces for the particle tracks; produce a data file for post processing results analysis; reads Abaqus .inp input (ASCII) files to obtain information for the global mesh-model; supports parallel input processing via mpi; and support parallel particle transport by both mpi and OpenMP.« less

Single-particle tracking: applications to membrane dynamics.

PubMed

Saxton, M J; Jacobson, K

1997-01-01

Measurements of trajectories of individual proteins or lipids in the plasma membrane of cells show a variety of types of motion. Brownian motion is observed, but many of the particles undergo non-Brownian motion, including directed motion, confined motion, and anomalous diffusion. The variety of motion leads to significant effects on the kinetics of reactions among membrane-bound species and requires a revision of existing views of membrane structure and dynamics.

Experimental study on spatio-temporal behavior of a single particle forming a particle accumulation structure (PAS) in half-zone liquid bridge

NASA Astrophysics Data System (ADS)

Oba, Takeru; Ueno, Ichiro; Kaneko, Toshihiro

2017-11-01

We focus on particle behavior due to thermocapillary-driven convection in a half-zone liquid bridge of high-Prandtl number fluid. It has been known that the suspended particles exhibit a unique solid-like structure known as 'particle accumulation structure (PAS)' in a rotating frame of reference with traveling-type hydrothermal wave. It is said that PAS is caused by interaction between particles and the free surface of a half-zone liquid bridge. Such structures arise even under small Stokes number conditions. When observing PAS two-dimensionally, it looks like a closed single string, but the actual movement of particles is different. Therefore we employ three-dimensional particle tracking velocimetry to the half-zone liquid bridge of 2.5 mm in radius and 1.7 mm in height, and detect the particle behaviors close to the free surface. We explain the spatio-temporal correlation between the solid-like global structure of PAS and the local particle motions, and make comparisons with proposed physical models of PAS formation.

Low material budget floating strip Micromegas for ion transmission radiography

NASA Astrophysics Data System (ADS)

Bortfeldt, J.; Biebel, O.; Flierl, B.; Hertenberger, R.; Klitzner, F.; Lösel, Ph.; Magallanes, L.; Müller, R.; Parodi, K.; Schlüter, T.; Voss, B.; Zibell, A.

2017-02-01

Floating strip Micromegas are high-accuracy and discharge insensitive gaseous detectors, able to track single particles at fluxes of 7 MHz/cm2 with 100 μm resolution. We developed low-material-budget detectors with one-dimensional strip readout, suitable for tracking at highest particle rates as encountered in medical ion transmission radiography or inner tracker applications. Recently we additionally developed Kapton-based floating strip Micromegas with two-dimensional strip readout, featuring an overall thickness of 0.011 X0. These detectors were tested in high-rate proton and carbon-ion beams at the tandem accelerator in Garching and the Heidelberg Ion-Beam Therapy Center, operated with an optimized Ne:CF4 gas mixture. By coupling the Micromegas detectors to a new scintillator based range detector, ion transmission radiographies of PMMA and tissue-equivalent phantoms were acquired. The range detector with 18 layers is read out via wavelength shifting fibers, coupled to a multi-anode photomultiplier. We present the performance of the Micromegas detectors with respect to timing and single plane track reconstruction using the μTPC method. We discuss the range resolution of the scintillator range telescope and present the image reconstruction capabilities of the combined system.

Deciphering dynamics of clathrin-mediated endocytosis in a living organism

PubMed Central

Heidotting, Spencer P.; Huber, Scott D.

2016-01-01

Current understanding of clathrin-mediated endocytosis (CME) dynamics is based on detection and tracking of fluorescently tagged clathrin coat components within cultured cells. Because of technical limitations inherent to detection and tracking of single fluorescent particles, CME dynamics is not characterized in vivo, so the effects of mechanical cues generated during development of multicellular organisms on formation and dissolution of clathrin-coated structures (CCSs) have not been directly observed. Here, we use growth rates of fluorescence signals obtained from short CCS intensity trace fragments to assess CME dynamics. This methodology does not rely on determining the complete lifespan of individual endocytic assemblies. Therefore, it allows for real-time monitoring of spatiotemporal changes in CME dynamics and is less prone to errors associated with particle detection and tracking. We validate the applicability of this approach to in vivo systems by demonstrating the reduction of CME dynamics during dorsal closure of Drosophila melanogaster embryos. PMID:27458134

The SATRAM Timepix spacecraft payload in open space on board the Proba-V satellite for wide range radiation monitoring in LEO orbit

NASA Astrophysics Data System (ADS)

Granja, Carlos; Polansky, Stepan; Vykydal, Zdenek; Pospisil, Stanislav; Owens, Alan; Kozacek, Zdenek; Mellab, Karim; Simcak, Marek

2016-06-01

The Space Application of Timepix based Radiation Monitor (SATRAM) is a spacecraft platform radiation monitor on board the Proba-V satellite launched in an 820 km altitude low Earth orbit in 2013. The is a technology demonstration payload is based on the Timepix chip equipped with a 300 μm silicon sensor with signal threshold of 8 keV/pixel to low-energy X-rays and all charged particles including minimum ionizing particles. For X-rays the energy working range is 10-30 keV. Event count rates can be up to 106 cnt/(cm2 s) for detailed event-by-event analysis or over 1011 cnt/(cm2 s) for particle-counting only measurements. The single quantum sensitivity (zero-dark current noise level) combined with per-pixel spectrometry and micro-scale pattern recognition analysis of single particle tracks enables the composition (particle type) and spectral characterization (energy loss) of mixed radiation fields to be determined. Timepix's pixel granularity and particle tracking capability also provides directional sensitivity for energetic charged particles. The payload detector response operates in wide dynamic range in terms of absorbed dose starting from single particle doses in the pGy level, particle count rate up to 106-10 /cm2/s and particle energy loss (threshold at 150 eV/μm). The flight model in orbit was successfully commissioned in 2013 and has been sampling the space radiation field in the satellite environment along its orbit at a rate of several frames per minute of varying exposure time. This article describes the design and operation of SATRAM together with an overview of the response and resolving power to the mixed radiation field including summary of the principal data products (dose rate, equivalent dose rate, particle-type count rate). The preliminary evaluation of response of the embedded Timepix detector to space radiation in the satellite environment is presented together with first results in the form of a detailed visualization of the mixed radiation field at the position of the payload and resulting spatial- and time-correlated radiation maps of cumulative dose rate along the satellite orbit.

Multi-pulse shadowgraphic RGB illumination and detection for flow tracking

NASA Astrophysics Data System (ADS)

Menser, Jan; Schneider, Florian; Dreier, Thomas; Kaiser, Sebastian A.

2018-06-01

This work demonstrates the application of a multi-color LED and a consumer color camera for visualizing phase boundaries in two-phase flows, in particular for particle tracking velocimetry. The LED emits a sequence of short light pulses, red, green, then blue (RGB), and through its color-filter array, the camera captures all three pulses on a single RGB frame. In a backlit configuration, liquid droplets appear as shadows in each color channel. Color reversal and color cross-talk correction yield a series of three frozen-flow images that can be used for further analysis, e.g., determining the droplet velocity by particle tracking. Three example flows are presented, solid particles suspended in water, the penetrating front of a gasoline direct-injection spray, and the liquid break-up region of an "air-assisted" nozzle. Because of the shadowgraphic arrangement, long path lengths through scattering media lower image contrast, while visualization of phase boundaries with high resolution is a strength of this method. Apart from a pulse-and-delay generator, the overall system cost is very low.

Optimizing Likelihood Models for Particle Trajectory Segmentation in Multi-State Systems.

PubMed

Young, Dylan Christopher; Scrimgeour, Jan

2018-06-19

Particle tracking offers significant insight into the molecular mechanics that govern the behav- ior of living cells. The analysis of molecular trajectories that transition between different motive states, such as diffusive, driven and tethered modes, is of considerable importance, with even single trajectories containing significant amounts of information about a molecule's environment and its interactions with cellular structures. Hidden Markov models (HMM) have been widely adopted to perform the segmentation of such complex tracks. In this paper, we show that extensive analysis of hidden Markov model outputs using data derived from multi-state Brownian dynamics simulations can be used both for the optimization of the likelihood models used to describe the states of the system and for characterization of the technique's failure mechanisms. This analysis was made pos- sible by the implementation of parallelized adaptive direct search algorithm on a Nvidia graphics processing unit. This approach provides critical information for the visualization of HMM failure and successful design of particle tracking experiments where trajectories contain multiple mobile states. © 2018 IOP Publishing Ltd.

Simultaneous acquisition of trajectory and fluorescence lifetime of moving single particles

NASA Astrophysics Data System (ADS)

Wu, Qianqian; Qi, Jing; Lin, Danying; Yan, Wei; Hu, Rui; Peng, Xiao; Qu, Junle

2017-02-01

Fluorescence lifetime imaging (FLIM) has been a powerful tool in life science because it can reveal the interactions of an excited fluorescent molecule and its environment. The combination with two-photon excitation (TPE) and timecorrelated single photon counting (TCSPC) provides it the ability of optical sectioning, high time resolution and detection efficiency. In previous work, we have introduced a two-dimensional acousto-optic deflector (AOD) into TCSPC-based FLIM to achieve fast and flexible FLIM. In this work, we combined the AOD-FLIM system with a single particle tracking (SPT) setup and algorithm and developed an SPT-FLIM system. Using the system, we acquired the trajectory and fluorescence lifetime of a moving particle simultaneously and reconstructed a life-time-marked pseudocolored trajectory, which might reflect dynamic interaction between the moving particle and its local environment along its motion trail. The results indicated the potential of the technique for studying the interaction between specific moving biological macromolecules and the ambient micro-environment in live cells.

Automatically processed alpha-track radon monitor

DOEpatents

Langner, Jr., G. Harold

1993-01-01

An automatically processed alpha-track radon monitor is provided which includes a housing having an aperture allowing radon entry, and a filter that excludes the entry of radon daughters into the housing. A flexible track registration material is located within the housing that records alpha-particle emissions from the decay of radon and radon daughters inside the housing. The flexible track registration material is capable of being spliced such that the registration material from a plurality of monitors can be spliced into a single strip to facilitate automatic processing of the registration material from the plurality of monitors. A process for the automatic counting of radon registered by a radon monitor is also provided.

Automatically processed alpha-track radon monitor

DOEpatents

Langner, G.H. Jr.

1993-01-12

An automatically processed alpha-track radon monitor is provided which includes a housing having an aperture allowing radon entry, and a filter that excludes the entry of radon daughters into the housing. A flexible track registration material is located within the housing that records alpha-particle emissions from the decay of radon and radon daughters inside the housing. The flexible track registration material is capable of being spliced such that the registration material from a plurality of monitors can be spliced into a single strip to facilitate automatic processing of the registration material from the plurality of monitors. A process for the automatic counting of radon registered by a radon monitor is also provided.

APM_GUI: analyzing particle movement on the cell membrane and determining confinement.

PubMed

Menchón, Silvia A; Martín, Mauricio G; Dotti, Carlos G

2012-02-20

Single-particle tracking is a powerful tool for tracking individual particles with high precision. It provides useful information that allows the study of diffusion properties as well as the dynamics of movement. Changes in particle movement behavior, such as transitions between Brownian motion and temporary confinement, can reveal interesting biophysical interactions. Although useful applications exist to determine the paths of individual particles, only a few software implementations are available to analyze these data, and these implementations are generally not user-friendly and do not have a graphical interface,. Here, we present APM_GUI (Analyzing Particle Movement), which is a MatLab-implemented application with a Graphical User Interface. This user-friendly application detects confined movement considering non-random confinement when a particle remains in a region longer than a Brownian diffusant would remain. In addition, APM_GUI exports the results, which allows users to analyze this information using software that they are familiar with. APM_GUI provides an open-source tool that quantifies diffusion coefficients and determines whether trajectories have non-random confinements. It also offers a simple and user-friendly tool that can be used by individuals without programming skills.

In Situ Observation of Single-Phase Lithium Intercalation in Sub-25-nm Nanoparticles

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

Zhong, Li; Liu, Yang; Han, Wei-Qiang

Although a non-equilibrium single-phase reaction, with the absence of nucleation and growth of a second phase, is believed to be a key factor for high-rate performance of lithium-ion batteries, it is thermodynamically unfavorable and usually proceeds in electrode materials with small particle sizes (tens of nanometers). Unfortunately, the phase evolutions inside such small particles are often shrouded by the macroscopic inhomogeneous reactions of electrodes containing millions of particles, leading to intensive debate over the size-dependent microscopic reaction mechanisms. Here, we provide a generally applicable methodology based on in-situ electron diffraction study on a multi-particle system to track the lithiation pathwaysmore » in individual nanoparticles, and unambiguously reveal that lithiation of anatase TiO 2, previously long believed to be biphasic, converts to a single-phase reaction when the particle size is below ~25 nm. Our results imply the prevalence of such a size-dependent transition in lithiation mechanism among intercalation compounds whose lithium miscibility gaps are associated with a prominent size effect, and therefore provide important guidelines for designing high-power electrodes, especially cathodes.« less

In Situ Observation of Single-Phase Lithium Intercalation in Sub-25-nm Nanoparticles

DOE PAGES

Zhong, Li; Liu, Yang; Han, Wei-Qiang; ...

2017-05-05

Although a non-equilibrium single-phase reaction, with the absence of nucleation and growth of a second phase, is believed to be a key factor for high-rate performance of lithium-ion batteries, it is thermodynamically unfavorable and usually proceeds in electrode materials with small particle sizes (tens of nanometers). Unfortunately, the phase evolutions inside such small particles are often shrouded by the macroscopic inhomogeneous reactions of electrodes containing millions of particles, leading to intensive debate over the size-dependent microscopic reaction mechanisms. Here, we provide a generally applicable methodology based on in-situ electron diffraction study on a multi-particle system to track the lithiation pathwaysmore » in individual nanoparticles, and unambiguously reveal that lithiation of anatase TiO 2, previously long believed to be biphasic, converts to a single-phase reaction when the particle size is below ~25 nm. Our results imply the prevalence of such a size-dependent transition in lithiation mechanism among intercalation compounds whose lithium miscibility gaps are associated with a prominent size effect, and therefore provide important guidelines for designing high-power electrodes, especially cathodes.« less

Comparisons of Particle Tracking Techniques and Galerkin Finite Element Methods in Flow Simulations on Watershed Scales

NASA Astrophysics Data System (ADS)

Shih, D.; Yeh, G.

2009-12-01

This paper applies two numerical approximations, the particle tracking technique and Galerkin finite element method, to solve the diffusive wave equation in both one-dimensional and two-dimensional flow simulations. The finite element method is one of most commonly approaches in numerical problems. It can obtain accurate solutions, but calculation times may be rather extensive. The particle tracking technique, using either single-velocity or average-velocity tracks to efficiently perform advective transport, could use larger time-step sizes than the finite element method to significantly save computational time. Comparisons of the alternative approximations are examined in this poster. We adapt the model WASH123D to examine the work. WASH123D is an integrated multimedia, multi-processes, physics-based computational model suitable for various spatial-temporal scales, was first developed by Yeh et al., at 1998. The model has evolved in design capability and flexibility, and has been used for model calibrations and validations over the course of many years. In order to deliver a locally hydrological model in Taiwan, the Taiwan Typhoon and Flood Research Institute (TTFRI) is working with Prof. Yeh to develop next version of WASH123D. So, the work of our preliminary cooperationx is also sketched in this poster.

Single-Camera Stereoscopy Setup to Visualize 3D Dusty Plasma Flows

NASA Astrophysics Data System (ADS)

Romero-Talamas, C. A.; Lemma, T.; Bates, E. M.; Birmingham, W. J.; Rivera, W. F.

2016-10-01

A setup to visualize and track individual particles in multi-layered dusty plasma flows is presented. The setup consists of a single camera with variable frame rate, and a pair of adjustable mirrors that project the same field of view from two different angles to the camera, allowing for three-dimensional tracking of particles. Flows are generated by inclining the plane in which the dust is levitated using a specially designed setup that allows for external motion control without compromising vacuum. Dust illumination is achieved with an optics arrangement that includes a Powell lens that creates a laser fan with adjustable thickness and with approximately constant intensity everywhere. Both the illumination and the stereoscopy setup allow for the camera to be placed at right angles with respect to the levitation plane, in preparation for magnetized dusty plasma experiments in which there will be no direct optical access to the levitation plane. Image data and analysis of unmagnetized dusty plasma flows acquired with this setup are presented.

Modification of a medical PET scanner for PEPT studies

NASA Astrophysics Data System (ADS)

Sadrmomtaz, Alireza; Parker, D. J.; Byars, L. G.

2007-04-01

Over the last 20 years, positron emission tomography (PET) has developed as the most powerful functional imaging modality in medicine. Over the same period the University of Birmingham Positron Imaging Centre has applied PET to study engineering processes and developed the alternative technique of positron emission particle tracking (PEPT) in which a single radioactively labelled tracer particle is tracked by detecting simultaneously the pairs of back-to-back photons arising from positron/electron annihilation. Originally PEPT was performed using a pair of multiwire detectors, and more recently using a pair of digital gamma camera heads. In 2002 the Positron Imaging Centre acquired a medical PET scanner, an ECAT 931/08, previously used at Hammersmith Hospital. This scanner has been rebuilt in a flexible geometry for use in PEPT studies. This paper presents initial results from this system. Fast moving tracer particles can be rapidly and accurately located.

Analysis of Video-Based Microscopic Particle Trajectories Using Kalman Filtering

PubMed Central

Wu, Pei-Hsun; Agarwal, Ashutosh; Hess, Henry; Khargonekar, Pramod P.; Tseng, Yiider

2010-01-01

Abstract The fidelity of the trajectories obtained from video-based particle tracking determines the success of a variety of biophysical techniques, including in situ single cell particle tracking and in vitro motility assays. However, the image acquisition process is complicated by system noise, which causes positioning error in the trajectories derived from image analysis. Here, we explore the possibility of reducing the positioning error by the application of a Kalman filter, a powerful algorithm to estimate the state of a linear dynamic system from noisy measurements. We show that the optimal Kalman filter parameters can be determined in an appropriate experimental setting, and that the Kalman filter can markedly reduce the positioning error while retaining the intrinsic fluctuations of the dynamic process. We believe the Kalman filter can potentially serve as a powerful tool to infer a trajectory of ultra-high fidelity from noisy images, revealing the details of dynamic cellular processes. PMID:20550894

Live-cell imaging reveals the dynamics and function of single-telomere TERRA molecules in cancer cells.

PubMed

Avogaro, Laura; Querido, Emmanuelle; Dalachi, Myriam; Jantsch, Michael F; Chartrand, Pascal; Cusanelli, Emilio

2018-04-16

Telomeres cap the ends of eukaryotic chromosomes, protecting them from degradation and erroneous recombination events which may lead to genome instability. Telomeres are transcribed giving rise to telomeric repeat-containing RNAs, called TERRA. The TERRA long noncoding RNAs have been proposed to play important roles in telomere biology, including heterochromatin formation and telomere length homeostasis. While TERRA RNAs are predominantly nuclear and localize at telomeres, little is known about the dynamics and function of TERRA molecules expressed from individual telomeres. Herein, we developed an assay to image endogenous TERRA molecules expressed from a single telomere in living human cancer cells. We show that single-telomere TERRA can be detected as TERRA RNA single particles which freely diffuse within the nucleus. Furthermore, TERRA molecules aggregate forming TERRA clusters. Three-dimensional size distribution and single particle tracking analyses revealed distinct sizes and dynamics for TERRA RNA single particles and clusters. Simultaneous time lapse confocal imaging of TERRA particles and telomeres showed that TERRA clusters transiently co-localize with telomeres. Finally, we used chemically modified antisense oligonucleotides to deplete TERRA molecules expressed from a single telomere. Single-telomere TERRA depletion resulted in increased DNA damage at telomeres and elsewhere in the genome. These results suggest that single-telomere TERRA transcripts participate in the maintenance of genomic integrity in human cancer cells.

A Preliminary Comparison of Three Dimensional Particle Tracking and Sizing using Plenoptic Imaging and Digital In-line Holography

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

Guildenbecher, Daniel Robert; Munz, Elise Dahnke; Farias, Paul Abraham

2015-12-01

Digital in-line holography and plenoptic photography are two techniques for single-shot, volumetric measurement of 3D particle fields. Here we present a preliminary comparison of the two methods by applying plenoptic imaging to experimental configurations that have been previously investigated with digital in-line holography. These experiments include the tracking of secondary droplets from the impact of a water drop on a thin film of water and tracking of pellets from a shotgun. Both plenoptic imaging and digital in-line holography successfully quantify the 3D nature of these particle fields. This includes measurement of the 3D particle position, individual particle sizes, and three-componentmore » velocity vectors. For the initial processing methods presented here, both techniques give out-of-plane positional accuracy of approximately 1-2 particle diameters. For a fixed image sensor, digital holography achieves higher effective in-plane spatial resolutions. However, collimated and coherent illumination makes holography susceptible to image distortion through index of refraction gradients, as demonstrated in the shotgun experiments. On the other hand, plenotpic imaging allows for a simpler experimental configuration. Furthermore, due to the use of diffuse, white-light illumination, plenoptic imaging is less susceptible to image distortion in the shotgun experiments. Additional work is needed to better quantify sources of uncertainty, particularly in the plenoptic experiments, as well as develop data processing methodologies optimized for the plenoptic measurement.« less

A Preliminary Comparison of Three Dimensional Particle Tracking and Sizing using Plenoptic Imaging and Digital In-line Holography [PowerPoint

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

Guildenbecher, Daniel Robert; Munz, Elise Dahnke; Farias, Paul Abraham

2015-12-01

Digital in-line holography and plenoptic photography are two techniques for single-shot, volumetric measurement of 3D particle fields. Here we present a preliminary comparison of the two methods by applying plenoptic imaging to experimental configurations that have been previously investigated with digital in-line holography. These experiments include the tracking of secondary droplets from the impact of a water drop on a thin film of water and tracking of pellets from a shotgun. Both plenoptic imaging and digital in-line holography successfully quantify the 3D nature of these particle fields. This includes measurement of the 3D particle position, individual particle sizes, and three-componentmore » velocity vectors. For the initial processing methods presented here, both techniques give out-of-plane positional accuracy of approximately 1-2 particle diameters. For a fixed image sensor, digital holography achieves higher effective in-plane spatial resolutions. However, collimated and coherent illumination makes holography susceptible to image distortion through index of refraction gradients, as demonstrated in the shotgun experiments. On the other hand, plenotpic imaging allows for a simpler experimental configuration. Furthermore, due to the use of diffuse, white-light illumination, plenoptic imaging is less susceptible to image distortion in the shotgun experiments. Additional work is needed to better quantify sources of uncertainty, particularly in the plenoptic experiments, as well as develop data processing methodologies optimized for the plenoptic measurement.« less

Dose-equivalent neutron dosimeter

DOEpatents

Griffith, R.V.; Hankins, D.E.; Tomasino, L.; Gomaa, M.A.M.

1981-01-07

A neutron dosimeter is disclosed which provides a single measurement indicating the amount of potential biological damage resulting from the neutron exposure of the wearer, for a wide range of neutron energies. The dosimeter includes a detecting sheet of track etch detecting material such as a carbonate plastic, for detecting higher energy neutrons, and a radiator layer contaning conversion material such as /sup 6/Li and /sup 10/B lying adjacent to the detecting sheet for converting moderate energy neutrons to alpha particles that produce tracks in the adjacent detecting sheet.

Particle tracking in drug and gene delivery research: State-of-the-art applications and methods.

PubMed

Schuster, Benjamin S; Ensign, Laura M; Allan, Daniel B; Suk, Jung Soo; Hanes, Justin

2015-08-30

Particle tracking is a powerful microscopy technique to quantify the motion of individual particles at high spatial and temporal resolution in complex fluids and biological specimens. Particle tracking's applications and impact in drug and gene delivery research have greatly increased during the last decade. Thanks to advances in hardware and software, this technique is now more accessible than ever, and can be reliably automated to enable rapid processing of large data sets, thereby further enhancing the role that particle tracking will play in drug and gene delivery studies in the future. We begin this review by discussing particle tracking-based advances in characterizing extracellular and cellular barriers to therapeutic nanoparticles and in characterizing nanoparticle size and stability. To facilitate wider adoption of the technique, we then present a user-friendly review of state-of-the-art automated particle tracking algorithms and methods of analysis. We conclude by reviewing technological developments for next-generation particle tracking methods, and we survey future research directions in drug and gene delivery where particle tracking may be useful. Copyright © 2015 Elsevier B.V. All rights reserved.

Adaptive track scheduling to optimize concurrency and vectorization in GeantV

DOE PAGES

Apostolakis, J.; Bandieramonte, M.; Bitzes, G.; ...

2015-05-22

The GeantV project is focused on the R&D of new particle transport techniques to maximize parallelism on multiple levels, profiting from the use of both SIMD instructions and co-processors for the CPU-intensive calculations specific to this type of applications. In our approach, vectors of tracks belonging to multiple events and matching different locality criteria must be gathered and dispatched to algorithms having vector signatures. While the transport propagates tracks and changes their individual states, data locality becomes harder to maintain. The scheduling policy has to be changed to maintain efficient vectors while keeping an optimal level of concurrency. The modelmore » has complex dynamics requiring tuning the thresholds to switch between the normal regime and special modes, i.e. prioritizing events to allow flushing memory, adding new events in the transport pipeline to boost locality, dynamically adjusting the particle vector size or switching between vector to single track mode when vectorization causes only overhead. Lastly, this work requires a comprehensive study for optimizing these parameters to make the behaviour of the scheduler self-adapting, presenting here its initial results.« less

Adaptation of multidimensional group particle tracking and particle wall-boundary condition model to the FDNS code

NASA Technical Reports Server (NTRS)

Chen, Y. S.; Farmer, R. C.

1992-01-01

A particulate two-phase flow CFD model was developed based on the FDNS code which is a pressure based predictor plus multi-corrector Navier-Stokes flow solver. Turbulence models with compressibility correction and the wall function models were employed as submodels. A finite-rate chemistry model was used for reacting flow simulation. For particulate two-phase flow simulations, a Eulerian-Lagrangian solution method using an efficient implicit particle trajectory integration scheme was developed in this study. Effects of particle-gas reaction and particle size change to agglomeration or fragmentation were not considered in this investigation. At the onset of the present study, a two-dimensional version of FDNS which had been modified to treat Lagrangian tracking of particles (FDNS-2DEL) had already been written and was operational. The FDNS-2DEL code was too slow for practical use, mainly because it had not been written in a form amenable to vectorization on the Cray, nor was the full three-dimensional form of FDNS utilized. The specific objective of this study was to reorder to calculations into long single arrays for automatic vectorization on the Cray and to implement the full three-dimensional version of FDNS to produce the FDNS-3DEL code. Since the FDNS-2DEL code was slow, a very limited number of test cases had been run with it. This study was also intended to increase the number of cases simulated to verify and improve, as necessary, the particle tracking methodology coded in FDNS.

Multisensor fusion for 3D target tracking using track-before-detect particle filter

NASA Astrophysics Data System (ADS)

Moshtagh, Nima; Romberg, Paul M.; Chan, Moses W.

2015-05-01

This work presents a novel fusion mechanism for estimating the three-dimensional trajectory of a moving target using images collected by multiple imaging sensors. The proposed projective particle filter avoids the explicit target detection prior to fusion. In projective particle filter, particles that represent the posterior density (of target state in a high-dimensional space) are projected onto the lower-dimensional observation space. Measurements are generated directly in the observation space (image plane) and a marginal (sensor) likelihood is computed. The particles states and their weights are updated using the joint likelihood computed from all the sensors. The 3D state estimate of target (system track) is then generated from the states of the particles. This approach is similar to track-before-detect particle filters that are known to perform well in tracking dim and stealthy targets in image collections. Our approach extends the track-before-detect approach to 3D tracking using the projective particle filter. The performance of this measurement-level fusion method is compared with that of a track-level fusion algorithm using the projective particle filter. In the track-level fusion algorithm, the 2D sensor tracks are generated separately and transmitted to a fusion center, where they are treated as measurements to the state estimator. The 2D sensor tracks are then fused to reconstruct the system track. A realistic synthetic scenario with a boosting target was generated, and used to study the performance of the fusion mechanisms.

Hydrodynamics of soap films probed by two-particle microrheology

NASA Astrophysics Data System (ADS)

Prasad, Vikram; Weeks, Eric R.

2007-11-01

A soap film consists of a thin water layer that is separated from two bulk air phases above and below it by surfactant monolayers. The flow fields in the soap film created in response to a perturbation depend on coupling between these different phases, the exact nature of which is unknown. In order to determine this coupling, we use polystyrene spheres as tracer particles and track their diffusive motions in the soap film. The correlated Brownian motion of pairs of particles (two-particle microrheology) maps out the flow field, and provides a measure of the surface viscosity of the soap film as well. This measured surface viscosity agrees well with the value obtained from self diffusion of single particles (one-particle microrheology) in the film.

Three dimensional time-gated tracking of non-blinking quantum dots in live cells

DOE PAGES

DeVore, Matthew S.; Werner, James H.; Goodwin, Peter M.; ...

2015-03-12

Single particle tracking has provided a wealth of information about biophysical processes such as motor protein transport and diffusion in cell membranes. However, motion out of the plane of the microscope or blinking of the fluorescent probe used as a label generally limits observation times to several seconds. Here, we overcome these limitations by using novel non-blinking quantum dots as probes and employing a custom 3D tracking microscope to actively follow motion in three dimensions (3D) in live cells. As a result, signal-to-noise is improved in the cellular milieu through the use of pulsed excitation and time-gated detection.

3D Tracking of Diatom Motion in Turbulent Flow

NASA Astrophysics Data System (ADS)

Variano, E. A.; Brandt, L.; Sardina, G.; Ardekani, M.; Pujara, N.; Ayers, S.; Du Clos, K.; Karp-Boss, L.; Jumars, P. A.

2016-02-01

We present laboratory measurements of single-celled and chain forming diatom motion in a stirred turbulence tank. The overarching goal is to explore whether diatoms track flow with fidelity (passive tracers) or whether interactions with cell density and shape result in biased trajectories that alter settling velocities. Diatom trajectories are recorded in 3D using a stereoscopic, calibrated tracking tool. Turbulence is created in a novel stirred tank, designed to create motions that match those found in the ocean surface mixed layer at scales less than 10 cm. The data are analyzed for evidence of enhanced particle clustering, an indicator of turbulently altered settling rates

Magnetic poly(lactide-co-glycolide) (PLGA) and cellulose particles for MRI-based cell tracking

PubMed Central

Nkansah, Michael K.; Thakral, Durga; Shapiro, Erik M.

2010-01-01

Biodegradable, superparamagnetic micro- and nanoparticles of poly(lactide-co-glycolide) (PLGA) and cellulose were designed, fabricated and characterized for magnetic cell labeling. Monodisperse nanocrystals of magnetite were incorporated into micro- and nanoparticles of PLGA and cellulose with high efficiency using an oil-in-water single emulsion technique. Superparamagnetic cores had high magnetization (72.1 emu/g). The resulting polymeric particles had smooth surface morphology and high magnetite content (43.3 wt% for PLGA and 69.6 wt% for cellulose). While PLGA and cellulose nanoparticles displayed highest r2* values per millimole of iron (399 s-1mM-1 for cellulose and 505 s-1mM-1 for PLGA), micron-sized PLGA particles had a much higher r2* per particle than either. After incubation for a month in citrate buffer (pH 5.5), magnetic PLGA particles lost close to 50% of their initial r2* molar relaxivity, while magnetic cellulose particles remained intact, preserving over 85% of their initial r2* molar relaxivity. Lastly, mesenchymal stem cells and human breast adenocarcinoma cells were magnetically labeled using these particles with no detectable cytotoxicity. These particles are ideally suited for non-invasive cell tracking in vivo via MRI and due to their vastly different degradation properties, offer unique potential for dedicated use for either short (PLGA-based particles) or long term (cellulose-based particles) experiments. PMID:21404328

Use of a ground-water flow model with particle tracking to evaluate ground-water vulnerability, Clark County, Washington

USGS Publications Warehouse

Snyder, D.T.; Wilkinson, J.M.; Orzol, L.L.

1996-01-01

A ground-water flow model was used in conjunction with particle tracking to evaluate ground-water vulnerability in Clark County, Washington. Using the particle-tracking program, particles were placed in every cell of the flow model (about 60,000 particles) and tracked backwards in time and space upgradient along flow paths to their recharge points. A new computer program was developed that interfaces the results from a particle-tracking program with a geographic information system (GIS). The GIS was used to display and analyze the particle-tracking results. Ground-water vulnerability was evaluated by selecting parts of the ground-water flow system and combining the results with ancillary information stored in the GIS to determine recharge areas, characteristics of recharge areas, downgradient impact of land use at recharge areas, and age of ground water. Maps of the recharge areas for each hydrogeologic unit illustrate the presence of local, intermediate, or regional ground-water flow systems and emphasize the three-dimensional nature of the ground-water flow system in Clark County. Maps of the recharge points for each hydrogeologic unit were overlaid with maps depicting aquifer sensitivity as determined by DRASTIC (a measure of the pollution potential of ground water, based on the intrinsic characteristics of the near-surface unsaturated and saturated zones) and recharge from on-site waste-disposal systems. A large number of recharge areas were identified, particularly in southern Clark County, that have a high aquifer sensitivity, coincide with areas of recharge from on-site waste-disposal systems, or both. Using the GIS, the characteristics of the recharge areas were related to the downgradient parts of the ground-water system that will eventually receive flow that has recharged through these areas. The aquifer sensitivity, as indicated by DRASTIC, of the recharge areas for downgradient parts of the flow system was mapped for each hydrogeologic unit. A number of public-supply wells in Clark County may be receiving a component of water that recharged in areas that are more conducive to contaminant entry. The aquifer sensitivity maps illustrate a critical deficiency in the DRASTIC methodology: the failure to account for the dynamics of the ground-water flow system. DRASTIC indices calculated for a particular location thus do not necessarily reflect the conditions of the ground-water resources at the recharge areas to that particular location. Each hydrogeologic unit was also mapped to highlight those areas that will eventually receive flow from recharge areas with on-site waste-disposal systems. Most public-supply wells in southern Clark County may eventually receive a component of water that was recharged from on-site waste-disposal systems.Traveltimes from particle tracking were used to estimate the minimum and maximum age of ground water within each model-grid cell. Chlorofluorocarbon (CFC)-age dating of ground water from 51 wells was used to calibrate effective porosity values used for the particle- tracking program by comparison of ground-water ages determined through the use of the CFC-age dating with those calculated by the particle- tracking program. There was a 76 percent agreement in predicting the presence of modern water in the 51 wells as determined using CFCs and calculated by the particle-tracking program. Maps showing the age of ground water were prepared for all the hydrogeologic units. Areas with the youngest ground-water ages are expected to be at greatest risk for contamination from anthropogenic sources. Comparison of these maps with maps of public- supply wells in Clark County indicates that most of these wells may withdraw ground water that is, in part, less than 100 years old, and in many instances less than 10 years old. Results of the analysis showed that a single particle-tracking analysis simulating advective transport can be used to evaluate ground-water vulnerability for any part of a ground-wate

Optical modeling of volcanic ash particles using ellipsoids

NASA Astrophysics Data System (ADS)

Merikallio, Sini; Muñoz, Olga; Sundström, Anu-Maija; Virtanen, Timo H.; Horttanainen, Matti; de Leeuw, Gerrit; Nousiainen, Timo

2015-05-01

The single-scattering properties of volcanic ash particles are modeled here by using ellipsoidal shapes. Ellipsoids are expected to improve the accuracy of the retrieval of aerosol properties using remote sensing techniques, which are currently often based on oversimplified assumptions of spherical ash particles. Measurements of the single-scattering optical properties of ash particles from several volcanoes across the globe, including previously unpublished measurements from the Eyjafjallajökull and Puyehue volcanoes, are used to assess the performance of the ellipsoidal particle models. These comparisons between the measurements and the ellipsoidal particle model include consideration of the whole scattering matrix, as well as sensitivity studies on the point of view of the Advanced Along Track Scanning Radiometer (AATSR) instrument. AATSR, which flew on the ENVISAT satellite, offers two viewing directions but no information on polarization, so usually only the phase function is relevant for interpreting its measurements. As expected, ensembles of ellipsoids are able to reproduce the observed scattering matrix more faithfully than spheres. Performance of ellipsoid ensembles depends on the distribution of particle shapes, which we tried to optimize. No single specific shape distribution could be found that would perform superiorly in all situations, but all of the best-fit ellipsoidal distributions, as well as the additionally tested equiprobable distribution, improved greatly over the performance of spheres. We conclude that an equiprobable shape distribution of ellipsoidal model particles is a relatively good, yet enticingly simple, approach for modeling volcanic ash single-scattering optical properties.

GPU-Based Interactive Exploration and Online Probability Maps Calculation for Visualizing Assimilated Ocean Ensembles Data

NASA Astrophysics Data System (ADS)

Hoteit, I.; Hollt, T.; Hadwiger, M.; Knio, O. M.; Gopalakrishnan, G.; Zhan, P.

2016-02-01

Ocean reanalyses and forecasts are nowadays generated by combining ensemble simulations with data assimilation techniques. Most of these techniques resample the ensemble members after each assimilation cycle. Tracking behavior over time, such as all possible paths of a particle in an ensemble vector field, becomes very difficult, as the number of combinations rises exponentially with the number of assimilation cycles. In general a single possible path is not of interest but only the probabilities that any point in space might be reached by a particle at some point in time. We present an approach using probability-weighted piecewise particle trajectories to allow for interactive probability mapping. This is achieved by binning the domain and splitting up the tracing process into the individual assimilation cycles, so that particles that fall into the same bin after a cycle can be treated as a single particle with a larger probability as input for the next cycle. As a result we loose the possibility to track individual particles, but can create probability maps for any desired seed at interactive rates. The technique is integrated in an interactive visualization system that enables the visual analysis of the particle traces side by side with other forecast variables, such as the sea surface height, and their corresponding behavior over time. By harnessing the power of modern graphics processing units (GPUs) for visualization as well as computation, our system allows the user to browse through the simulation ensembles in real-time, view specific parameter settings or simulation models and move between different spatial or temporal regions without delay. In addition our system provides advanced visualizations to highlight the uncertainty, or show the complete distribution of the simulations at user-defined positions over the complete time series of the domain.

Mitochondrial fluctuations as a measure of active biomechanical properties of mammalian cells

NASA Astrophysics Data System (ADS)

Xu, Wenlong; Alizadeh, Elaheh; Castle, Jordan; Prasad, Ashok

A single-cell assay of mechanical properties would give significant insights into cellular processes. Force spectrum microscopy is one such technique, which involves both active and passive particle tracking microrheology on the same cells. Since active microrheology requires expensive instruments, it is of great interest to develop simpler alternatives. Here we study an alternative using endogenous mitochondrial fluctuations, rather than fluorescent beads, in particle tracking microrheology. Mitochondria of the C3H-10T1/2 cell line are labeled and tracked using confocal microscopy, their mean square displacement (MSD) measured, and mechanical parameters calculated. Active fluctuations are distinguished from passive fluctuations by treatment with ATP synthesis inhibitors. We find that the MSD of mitochondria resembles that of particles in viscoelastic media. However, comparisons of MSD between controls and cells disrupted in the actin or microtubule network showed surprisingly small effects, while ATP-depleted cells showed significantly decreased MSD, and characteristics of thermally driven fluctuations. Both active and ATP-depleted parameters showed heterogeneity among cells and between cell lines. This method is potentially very useful due to its simplicity. We gratefully acknowledge support from NSF CAREER Grant PHY-1151454 awarded to Ashok Prasad.

Secondary particle tracks generated by ion beam irradiation

NASA Astrophysics Data System (ADS)

García, Gustavo

2015-05-01

The Low Energy Particle Track Simulation (LEPTS) procedure is a powerful complementary tool to include the effect of low energy electrons and positrons in medical applications of radiation. In particular, for ion-beam cancer treatments provides a detailed description of the role of the secondary electrons abundantly generated around the Bragg peak as well as the possibility of using transmuted positron emitters (C11, O15) as a complement for ion-beam dosimetry. In this study we present interaction probability data derived from IAM-SCAR corrective factors for liquid environments. Using these data, single electron and positron tracks in liquid water and pyrimidine have been simulated providing information about energy deposition as well as the number and type of interactions taking place in any selected ``nanovolume'' of the irradiated area. In collaboration with Francisco Blanco, Universidad Complutense de Madrid; Antonio Mu noz, Centro de Investigaciones Energéticas Medioambientales y Tecnológicas and Diogo Almeida, Filipe Ferreira da Silva, Paulo Lim ao-Vieira, Universidade Nova de Lisboa. Supported by the Spanish and Portuguese governments.

Distributed multi-sensor particle filter for bearings-only tracking

NASA Astrophysics Data System (ADS)

Zhang, Jungen; Ji, Hongbing

2012-02-01

In this article, the classical bearings-only tracking (BOT) problem for a single target is addressed, which belongs to the general class of non-linear filtering problems. Due to the fact that the radial distance observability of the target is poor, the algorithm-based sequential Monte-Carlo (particle filtering, PF) methods generally show instability and filter divergence. A new stable distributed multi-sensor PF method is proposed for BOT. The sensors process their measurements at their sites using a hierarchical PF approach, which transforms the BOT problem from Cartesian coordinate to the logarithmic polar coordinate and separates the observable components from the unobservable components of the target. In the fusion centre, the target state can be estimated by utilising the multi-sensor optimal information fusion rule. Furthermore, the computation of a theoretical Cramer-Rao lower bound is given for the multi-sensor BOT problem. Simulation results illustrate that the proposed tracking method can provide better performances than the traditional PF method.

Field calculations, single-particle tracking, and beam dynamics with space charge in the electron lens for the Fermilab Integrable Optics Test Accelerator

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

Noll, Daniel; Stancari, Giulio

2015-11-17

An electron lens is planned for the Fermilab Integrable Optics Test Accelerator as a nonlinear element for integrable dynamics, as an electron cooler, and as an electron trap to study space-charge compensation in rings. We present the main design principles and constraints for nonlinear integrable optics. A magnetic configuration of the solenoids and of the toroidal section is laid out. Singleparticle tracking is used to optimize the electron path. Electron beam dynamics at high intensity is calculated with a particle-in-cell code to estimate current limits, profile distortions, and the effects on the circulating beam. In the conclusions, we summarize themore » main findings and list directions for further work.« less

Visualizing single molecules interacting with nuclear pore complexes by narrow-field epifluorescence microscopy

PubMed Central

Yang, Weidong; Musser, Siegfried M.

2008-01-01

The utility of single molecule fluorescence (SMF) for understanding biological reactions has been amply demonstrated by a diverse series of studies over the last decade. In large part, the molecules of interest have been limited to those within a small focal volume or near a surface to achieve the high sensitivity required for detecting the inherently weak signals arising from individual molecules. Consequently, the investigation of molecular behavior with high time and spatial resolution deep within cells using SMF has remained challenging. Recently, we demonstrated that narrow-field epifluorescence microscopy allows visualization of nucleocytoplasmic transport at the single cargo level. We describe here the methodological approach that yields 2 ms and ∼15 nm resolution for a stationary particle. The spatial resolution for a mobile particle is inherently worse, and depends on how fast the particle is moving. The signal-to-noise ratio is sufficiently high to directly measure the time a single cargo molecule spends interacting with the nuclear pore complex. Particle tracking analysis revealed that cargo molecules randomly diffuse within the nuclear pore complex, exiting as a result of a single rate-limiting step. We expect that narrow-field epifluorescence microscopy will be useful for elucidating other binding and trafficking events within cells. PMID:16879979

Monitoring of Hadrontherapy Treatments by Means of Charged Particle Detection.

PubMed

Muraro, Silvia; Battistoni, Giuseppe; Collamati, Francesco; De Lucia, Erika; Faccini, Riccardo; Ferroni, Fernando; Fiore, Salvatore; Frallicciardi, Paola; Marafini, Michela; Mattei, Ilaria; Morganti, Silvio; Paramatti, Riccardo; Piersanti, Luca; Pinci, Davide; Rucinski, Antoni; Russomando, Andrea; Sarti, Alessio; Sciubba, Adalberto; Solfaroli-Camillocci, Elena; Toppi, Marco; Traini, Giacomo; Voena, Cecilia; Patera, Vincenzo

2016-01-01

The interaction of the incoming beam radiation with the patient body in hadrontherapy treatments produces secondary charged and neutral particles, whose detection can be used for monitoring purposes and to perform an on-line check of beam particle range. In the context of ion-therapy with active scanning, charged particles are potentially attractive since they can be easily tracked with a high efficiency, in presence of a relatively low background contamination. In order to verify the possibility of exploiting this approach for in-beam monitoring in ion-therapy, and to guide the design of specific detectors, both simulations and experimental tests are being performed with ion beams impinging on simple homogeneous tissue-like targets (PMMA). From these studies, a resolution of the order of few millimeters on the single track has been proven to be sufficient to exploit charged particle tracking for monitoring purposes, preserving the precision achievable on longitudinal shape. The results obtained so far show that the measurement of charged particles can be successfully implemented in a technology capable of monitoring both the dose profile and the position of the Bragg peak inside the target and finally lead to the design of a novel profile detector. Crucial aspects to be considered are the detector positioning, to be optimized in order to maximize the available statistics, and the capability of accounting for the multiple scattering interactions undergone by the charged fragments along their exit path from the patient body. The experimental results collected up to now are also valuable for the validation of Monte Carlo simulation software tools and their implementation in Treatment Planning Software packages.

Monitoring of Hadrontherapy Treatments by Means of Charged Particle Detection

PubMed Central

Muraro, Silvia; Battistoni, Giuseppe; Collamati, Francesco; De Lucia, Erika; Faccini, Riccardo; Ferroni, Fernando; Fiore, Salvatore; Frallicciardi, Paola; Marafini, Michela; Mattei, Ilaria; Morganti, Silvio; Paramatti, Riccardo; Piersanti, Luca; Pinci, Davide; Rucinski, Antoni; Russomando, Andrea; Sarti, Alessio; Sciubba, Adalberto; Solfaroli-Camillocci, Elena; Toppi, Marco; Traini, Giacomo; Voena, Cecilia; Patera, Vincenzo

2016-01-01

The interaction of the incoming beam radiation with the patient body in hadrontherapy treatments produces secondary charged and neutral particles, whose detection can be used for monitoring purposes and to perform an on-line check of beam particle range. In the context of ion-therapy with active scanning, charged particles are potentially attractive since they can be easily tracked with a high efficiency, in presence of a relatively low background contamination. In order to verify the possibility of exploiting this approach for in-beam monitoring in ion-therapy, and to guide the design of specific detectors, both simulations and experimental tests are being performed with ion beams impinging on simple homogeneous tissue-like targets (PMMA). From these studies, a resolution of the order of few millimeters on the single track has been proven to be sufficient to exploit charged particle tracking for monitoring purposes, preserving the precision achievable on longitudinal shape. The results obtained so far show that the measurement of charged particles can be successfully implemented in a technology capable of monitoring both the dose profile and the position of the Bragg peak inside the target and finally lead to the design of a novel profile detector. Crucial aspects to be considered are the detector positioning, to be optimized in order to maximize the available statistics, and the capability of accounting for the multiple scattering interactions undergone by the charged fragments along their exit path from the patient body. The experimental results collected up to now are also valuable for the validation of Monte Carlo simulation software tools and their implementation in Treatment Planning Software packages. PMID:27536555

Forward-backward multiplicity correlations of target fragments in nucleus-emulsion collisions at a few hundred MeV/u

NASA Astrophysics Data System (ADS)

Zhang, Dong-Hai; Chen, Yan-Ling; Wang, Guo-Rong; Li, Wang-Dong; Wang, Qing; Yao, Ji-Jie; Zhou, Jian-Guo; Li, Rong; Li, Jun-Sheng; Li, Hui-Ling

2015-01-01

The forward-backward multiplicity and correlations of a target evaporated fragment (black track particle) and target recoiled proton (grey track particle) emitted from 150 A MeV 4He, 290 A MeV 12C, 400 A MeV 12C, 400 A MeV 20Ne and 500 A MeV 56Fe induced different types of nuclear emulsion target interactions are investigated. It is found that the forward and backward averaged multiplicity of a grey, black and heavily ionized track particle increases with the increase of the target size. The averaged multiplicity of a forward black track particle, backward black track particle, and backward grey track particle do not depend on the projectile size and energy, but the averaged multiplicity of a forward grey track particle increases with an increase of projectile size and energy. The backward grey track particle multiplicity distribution follows an exponential decay law and the decay constant decreases with an increase of target size. The backward-forward multiplicity correlations follow linear law which is independent of the projectile size and energy, and the saturation effect is observed in some heavy target data sets.

Real-time particle tracking for studying intracellular trafficking of pharmaceutical nanocarriers.

PubMed

Huang, Feiran; Watson, Erin; Dempsey, Christopher; Suh, Junghae

2013-01-01

Real-time particle tracking is a technique that combines fluorescence microscopy with object tracking and computing and can be used to extract quantitative transport parameters for small particles inside cells. Since the success of a nanocarrier can often be determined by how effectively it delivers cargo to the target organelle, understanding the complex intracellular transport of pharmaceutical nanocarriers is critical. Real-time particle tracking provides insight into the dynamics of the intracellular behavior of nanoparticles, which may lead to significant improvements in the design and development of novel delivery systems. Unfortunately, this technique is not often fully understood, limiting its implementation by researchers in the field of nanomedicine. In this chapter, one of the most complicated aspects of particle tracking, the mean square displacement (MSD) calculation, is explained in a simple manner designed for the novice particle tracker. Pseudo code for performing the MSD calculation in MATLAB is also provided. This chapter contains clear and comprehensive instructions for a series of basic procedures in the technique of particle tracking. Instructions for performing confocal microscopy of nanoparticle samples are provided, and two methods of determining particle trajectories that do not require commercial particle-tracking software are provided. Trajectory analysis and determination of the tracking resolution are also explained. By providing comprehensive instructions needed to perform particle-tracking experiments, this chapter will enable researchers to gain new insight into the intracellular dynamics of nanocarriers, potentially leading to the development of more effective and intelligent therapeutic delivery vectors.

A Globally Optimal Particle Tracking Technique for Stereo Imaging Velocimetry Experiments

NASA Technical Reports Server (NTRS)

McDowell, Mark

2008-01-01

An important phase of any Stereo Imaging Velocimetry experiment is particle tracking. Particle tracking seeks to identify and characterize the motion of individual particles entrained in a fluid or air experiment. We analyze a cylindrical chamber filled with water and seeded with density-matched particles. In every four-frame sequence, we identify a particle track by assigning a unique track label for each camera image. The conventional approach to particle tracking is to use an exhaustive tree-search method utilizing greedy algorithms to reduce search times. However, these types of algorithms are not optimal due to a cascade effect of incorrect decisions upon adjacent tracks. We examine the use of a guided evolutionary neural net with simulated annealing to arrive at a globally optimal assignment of tracks. The net is guided both by the minimization of the search space through the use of prior limiting assumptions about valid tracks and by a strategy which seeks to avoid high-energy intermediate states which can trap the net in a local minimum. A stochastic search algorithm is used in place of back-propagation of error to further reduce the chance of being trapped in an energy well. Global optimization is achieved by minimizing an objective function, which includes both track smoothness and particle-image utilization parameters. In this paper we describe our model and present our experimental results. We compare our results with a nonoptimizing, predictive tracker and obtain an average increase in valid track yield of 27 percent

Transition from fractional to classical Stokes-Einstein behaviour in simple fluids.

PubMed

Coglitore, Diego; Edwardson, Stuart P; Macko, Peter; Patterson, Eann A; Whelan, Maurice

2017-12-01

An optical technique for tracking single particles has been used to evaluate the particle diameter at which diffusion transitions from molecular behaviour described by the fractional Stokes-Einstein relationship to particle behaviour described by the classical Stokes-Einstein relationship. The results confirm a prior prediction from molecular dynamic simulations that there is a particle size at which transition occurs and show it is inversely dependent on concentration and viscosity but independent of particle density. For concentrations in the range 5 × 10 -3 to 5 × 10 -6  mg ml -1 and viscosities from 0.8 to 150 mPa s, the transition was found to occur in the diameter range 150-300 nm.

Brownian Motion of Asymmetric Boomerang Colloidal Particles

NASA Astrophysics Data System (ADS)

Chakrabarty, Ayan; Konya, Andrew; Wang, Feng; Selinger, Jonathan; Sun, Kai; Wei, Qi-Huo

2014-03-01

We used video microscopy and single particle tracking to study the diffusion and local behaviors of asymmetric boomerang particles in a quasi-two dimensional geometry. The motion is biased towards the center of hydrodynamic stress (CoH) and the mean square displacements of the particles are linear at short and long times with different diffusion coefficients and in the crossover regime it is sub-diffusive. Our model based on Langevin theory shows that these behaviors arise from the non-coincidence of the CoH with the center of the body. Since asymmetric boomerangs represent a class of rigid bodies of more generals shape, therefore our findings are generic and true for any non-skewed particle in two dimensions. Both experimental and theoretical results will be discussed.

Numerical study of the vortex tube reconnection using vortex particle method on many graphics cards

NASA Astrophysics Data System (ADS)

Kudela, Henryk; Kosior, Andrzej

2014-08-01

Vortex Particle Methods are one of the most convenient ways of tracking the vorticity evolution. In the article we presented numerical recreation of the real life experiment concerning head-on collision of two vortex rings. In the experiment the evolution and reconnection of the vortex structures is tracked with passive markers (paint particles) which in viscous fluid does not follow the evolution of vorticity field. In numerical computations we showed the difference between vorticity evolution and movement of passive markers. The agreement with the experiment was very good. Due to problems with very long time of computations on a single processor the Vortex-in-Cell method was implemented on the multicore architecture of the graphics cards (GPUs). Vortex Particle Methods are very well suited for parallel computations. As there are myriads of particles in the flow and for each of them the same equations of motion have to be solved the SIMD architecture used in GPUs seems to be perfect. The main disadvantage in this case is the small amount of the RAM memory. To overcome this problem we created a multiGPU implementation of the VIC method. Some remarks on parallel computing are given in the article.

Non-iterative double-frame 2D/3D particle tracking velocimetry

NASA Astrophysics Data System (ADS)

Fuchs, Thomas; Hain, Rainer; Kähler, Christian J.

2017-09-01

In recent years, the detection of individual particle images and their tracking over time to determine the local flow velocity has become quite popular for planar and volumetric measurements. Particle tracking velocimetry has strong advantages compared to the statistical analysis of an ensemble of particle images by means of cross-correlation approaches, such as particle image velocimetry. Tracking individual particles does not suffer from spatial averaging and therefore bias errors can be avoided. Furthermore, the spatial resolution can be increased up to the sub-pixel level for mean fields. A maximization of the spatial resolution for instantaneous measurements requires high seeding concentrations. However, it is still challenging to track particles at high seeding concentrations, if no time series is available. Tracking methods used under these conditions are typically very complex iterative algorithms, which require expert knowledge due to the large number of adjustable parameters. To overcome these drawbacks, a new non-iterative tracking approach is introduced in this letter, which automatically analyzes the motion of the neighboring particles without requiring to specify any parameters, except for the displacement limits. This makes the algorithm very user friendly and also offers unexperienced users to use and implement particle tracking. In addition, the algorithm enables measurements of high speed flows using standard double-pulse equipment and estimates the flow velocity reliably even at large particle image densities.

Realizing the potential of the Actinium-225 radionuclide generator in targeted alpha-particle therapy applications

PubMed Central

Miederer, Matthias; Scheinberg, David A.; McDevitt, Michael R.

2013-01-01

Alpha particle-emitting isotopes have been proposed as novel cytotoxic agents for augmenting targeted therapy. Properties of alpha particle radiation such as their limited range in tissue of a few cell diameters and their high linear energy transfer leading to dense radiation damage along each alpha track are promising in the treatment of cancer, especially when single cells or clusters of tumor cells are targeted. Actinium-225 (225Ac) is an alpha particle-emitting radionuclide that generates 4 net alpha particle isotopes in a short decay chain to stable 209Bi, and as such can be described as an alpha particle nanogenerator. This article reviews the literature pertaining to the research, development, and utilization of targeted 225Ac to potently and specifically affect cancer. PMID:18514364

Confocal three dimensional tracking of a single nanoparticle with concurrent spectroscopic readouts

NASA Astrophysics Data System (ADS)

Cang, Hu; Wong, Chung M.; Xu, C. Shan; Rizvi, Abbas H.; Yang, Haw

2006-05-01

We present an apparatus that noninvasively tracks a moving nanoparticle in three dimensions while providing concurrent sequential spectroscopic measurements. The design, based on confocal microscopy, uses a near-infrared laser and a dark-field condenser for illumination of a gold nanoparticle. By monitoring the scattered light from the nanoparticle and using a piezoelectric stage, the system was able to continuously bring the diffusive particle in a glycerol/water solution back to the focal volume with spatial resolution and response time of less than 210nm and a millisecond, respectively.

Multiplexed single-molecule force spectroscopy using a centrifuge.

PubMed

Yang, Darren; Ward, Andrew; Halvorsen, Ken; Wong, Wesley P

2016-03-17

We present a miniature centrifuge force microscope (CFM) that repurposes a benchtop centrifuge for high-throughput single-molecule experiments with high-resolution particle tracking, a large force range, temperature control and simple push-button operation. Incorporating DNA nanoswitches to enable repeated interrogation by force of single molecular pairs, we demonstrate increased throughput, reliability and the ability to characterize population heterogeneity. We perform spatiotemporally multiplexed experiments to collect 1,863 bond rupture statistics from 538 traceable molecular pairs in a single experiment, and show that 2 populations of DNA zippers can be distinguished using per-molecule statistics to reduce noise.

Multiplexed single-molecule force spectroscopy using a centrifuge

PubMed Central

Yang, Darren; Ward, Andrew; Halvorsen, Ken; Wong, Wesley P.

2016-01-01

We present a miniature centrifuge force microscope (CFM) that repurposes a benchtop centrifuge for high-throughput single-molecule experiments with high-resolution particle tracking, a large force range, temperature control and simple push-button operation. Incorporating DNA nanoswitches to enable repeated interrogation by force of single molecular pairs, we demonstrate increased throughput, reliability and the ability to characterize population heterogeneity. We perform spatiotemporally multiplexed experiments to collect 1,863 bond rupture statistics from 538 traceable molecular pairs in a single experiment, and show that 2 populations of DNA zippers can be distinguished using per-molecule statistics to reduce noise. PMID:26984516

Biological effects of galactic radiation HZE particles in experiments on the orbital station Salyut 7

NASA Astrophysics Data System (ADS)

Miller, A. T.; Nevzgodina, L. V.

Lettuce (Lactuca sativa) seeds were flown on-board the orbital station Salyut 7 for 66-457 days. It was found that a single heavy charged particle (HZE) hitting a seed only slightly affects the subsequent plant growth. However, morphological anomalies of varying type in primordial leaves and roots were observed that show good correlation with the location of the particle track. The most severe damage detected by light and an electron microscopy were ``channels'' in dry and soaked seeds. The appearance of ``channels'' seems to be related to the LET of the incident particle. This finding is of considerable importance for assessment of space flight radiation hazard.

Simulation of ground-water flow and delineation of areas contributing recharge within the Mt. Simon-Hinckley Aquifer to well fields in the Prairie Island Indian Community, Minnesota

USGS Publications Warehouse

Ruhl, J.F.

2002-01-01

A steady state single layer, two-dimensional ground-water flow model constructed with the computer program MODFLOW,combined with the particle-tracking computer program MODPATH, was used to track water particles (upgradient) from the two well fields. A withdrawal rate of 625 m3/d was simulated for each well field. The ground-water flow paths delineated areas of contributing recharge that are 0.38 and 0.65 km2 based on 10- and 50-year travel times, respectively. The flow paths that define these areas extend for maximum distances of about 350 and 450 m, respectively, from the wells. At well field A the area of contributing recharge was delineated for each well as separate withdrawal points. At well field B the area of contributing recharge was delineated for the two wells as a single withdrawal point. Delineation of areas of contributing recharge to the well fields from land surface would require construction of a multi-layer ground-water flow model.

Nanoscopic compartmentalization of membrane protein motion at the axon initial segment.

PubMed

Albrecht, David; Winterflood, Christian M; Sadeghi, Mohsen; Tschager, Thomas; Noé, Frank; Ewers, Helge

2016-10-10

The axon initial segment (AIS) is enriched in specific adaptor, cytoskeletal, and transmembrane molecules. During AIS establishment, a membrane diffusion barrier is formed between the axonal and somatodendritic domains. Recently, an axonal periodic pattern of actin, spectrin, and ankyrin forming 190-nm-spaced, ring-like structures has been discovered. However, whether this structure is related to the diffusion barrier function is unclear. Here, we performed single-particle tracking time-course experiments on hippocampal neurons during AIS development. We analyzed the mobility of lipid-anchored molecules by high-speed single-particle tracking and correlated positions of membrane molecules with the nanoscopic organization of the AIS cytoskeleton. We observe a strong reduction in mobility early in AIS development. Membrane protein motion in the AIS plasma membrane is confined to a repetitive pattern of ∼190-nm-spaced segments along the AIS axis as early as day in vitro 4, and this pattern alternates with actin rings. Mathematical modeling shows that diffusion barriers between the segments significantly reduce lateral diffusion along the axon. © 2016 Albrecht et al.

Uncovering homo-and hetero-interactions on the cell membrane using single particle tracking approaches

NASA Astrophysics Data System (ADS)

Torreno-Pina, Juan A.; Manzo, Carlo; Garcia-Parajo, Maria F.

2016-03-01

The plasma membrane of eukaryotic cells is responsible for a myriad of functions that regulate cell physiology and plays a crucial role in a multitude of processes that include adhesion, migration, signaling recognition and cell-cell communication. This is accomplished by specific interactions between different membrane components such as lipids and proteins on the lipid bilayer but also through interactions with the underlying cortical actin cytoskeleton on the intracellular side and the glycocalyx matrix in close proximity to the extracellular side. Advanced biophysical techniques, including single particle tracking (SPT) have revealed that the lateral diffusion of molecular components on the plasma membrane represents a landmark manifestation of such interactions. Indeed, by studying changes in the diffusivity of individual membrane molecules, including sub-diffusion, confined diffusion and/or transient arrest of molecules in membrane compartments, it has been possible to gain insight on the nature of molecular interactions and to infer on its functional role for cell response. In this review, we will revise some exciting results where SPT has been crucial to reveal homo- and hetero-interactions on the cell membrane.

Three-Dimensional Visualization of Particle Tracks.

ERIC Educational Resources Information Center

Julian, Glenn M.

1993-01-01

Suggests ways to bring home to the introductory physics student some of the excitement of recent discoveries in particle physics. Describes particle detectors and encourages the use of the Standard Model along with real images of particle tracks to determine three-dimensional views of tracks. (MVL)

Principles and biophysical applications of single particle super-localization and rotational tracking

NASA Astrophysics Data System (ADS)

Gu, Yan

While conventional Single Particle Tracking (SPT) techniques acquire 2D or 3D trajectories of particle probes, we have developed Single Particle Orientation and Rotational Tracking (SPORT) techniques to extract orientation and rotational information. Combined with DIC microscopy, the SPORT technique has been applied in biophysical studies, including membrane diffusion and intracellular transport. The rotational dynamics of nanoparticle vectors on live cell membranes was recorded and its influence on the fate of these nanoparticle vectors was elucidated. The rotational motions of gold nanorods with various surface modifiers were tracked continuously at a temporal resolution of 5 ms under a DIC microscope. We found that the rotational behaviors of gold nanorod vectors are strongly related to their surface charge, specific surface functional groups, and the availability of receptors on cell membranes. The study of rotational Brownian motion of nanoparticles on cell membranes will lead to a better understanding of the mechanisms of drug delivery and provide guidance in designing surface modification strategies for drug delivery vectors under various circumstances. To characterize the rotation mode of surface functionalized gold nanorods on cell membranes, the SPORT technique is combined with the correlation analysis of the bright and dark DIC intensities. The unique capabilities of visualizing and understanding rotational motions of functionalized nanoparticles on live cell membranes allow us to correlate rotational and translational dynamics in unprecedented detail and provide new insights for complex membrane processes, including electrostatic interactions, ligand-receptor binding, and lateral (confined and hopping) diffusion of membrane receptors. Surface-functionalized nanoparticles interact with the membrane in fundamentally different ways and exhibit distinct rotational modes. The early events of particle-membrane approach and attachment are directly visualized for the first time. The rotational dynamics of cargos in both active directional transport and pausing stages of axonal transport was also visualized using high-speed SPORT with a temporal resolution of 2 ms. Both long and short pauses are imaged, and the correlations between the pause duration, the rotational behaviour of the cargo at the pause, and the moving direction after the pause are established. Furthermore, the rotational dynamics leading to switching tracks are visualized in detail. These first-time observations of cargo's rotational dynamics provide new insights on how kinesin and dynein motors take the cargo through the alternating stages of active directional transport and pause. To improve the localization precision of the SPT technique with DIC microscopy, a precise three-dimensional (3D) localization method of spherical gold nanoparticle probes using model-based correlation coefficient mapping was introduced. To accomplish this, a stack of sample images at different z-positions are acquired, and a 3D intensity profile of the probe serving as the model is used to map out the positions of nanoparticles in the sample. By using this model-based correlation imaging method, precise localization can be achieved in imaging techniques with complicated point spread functions (PSF) such as differential interference contrast (DIC) microscopy. The 3D superlocalization method was applied to tracking gold nanospheres during live endocytosis events. Finally, a novel dual-modality imaging technique has been developed to super-localize a single gold nanorod while providing its orientation and rotational information. The super-localization of the gold nanorod can be accomplished by curve fitting the modified bright-field images generated by one of the two beams laterally shifted by the first Nomarski prism in a DIC microscope. The orientation and rotational information is derived from the DIC images of gold nanorods. The new imaging setup has been applied to study the steric hindrance induced by relatively large cargos in the microtubule gliding assay and to track nanocargos in the crowded cellular environment.

Principles and biophysical applications of single particle super-localization and rotational tracking

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

Gu, Yan

While conventional Single Particle Tracking (SPT) techniques acquire 2D or 3D trajectories of particle probes, we have developed Single Particle Orientation and Rotational Tracking (SPORT) techniques to extract orientation and rotational information. Combined with DIC microscopy, the SPORT technique has been applied in biophysical studies, including membrane diffusion and intracellular transport. The rotational dynamics of nanoparticle vectors on live cell membranes was recorded and its influence on the fate of these nanoparticle vectors was elucidated. The rotational motions of gold nanorods with various surface modifiers were tracked continuously at a temporal resolution of 5 ms under a DIC microscope. Wemore » found that the rotational behaviors of gold nanorod vectors are strongly related to their surface charge, specific surface functional groups, and the availability of receptors on cell membranes. The study of rotational Brownian motion of nanoparticles on cell membranes will lead to a better understanding of the mechanisms of drug delivery and provide guidance in designing surface modification strategies for drug delivery vectors under various circumstances. To characterize the rotation mode of surface functionalized gold nanorods on cell membranes, the SPORT technique is combined with the correlation analysis of the bright and dark DIC intensities. The unique capabilities of visualizing and understanding rotational motions of functionalized nanoparticles on live cell membranes allow us to correlate rotational and translational dynamics in unprecedented detail and provide new insights for complex membrane processes, including electrostatic interactions, ligand-receptor binding, and lateral (confined and hopping) diffusion of membrane receptors. Surface-functionalized nanoparticles interact with the membrane in fundamentally different ways and exhibit distinct rotational modes. The early events of particle-membrane approach and attachment are directly visualized for the first time. The rotational dynamics of cargos in both active directional transport and pausing stages of axonal transport was also visualized using high-speed SPORT with a temporal resolution of 2 ms. Both long and short pauses are imaged, and the correlations between the pause duration, the rotational behaviour of the cargo at the pause, and the moving direction after the pause are established. Furthermore, the rotational dynamics leading to switching tracks are visualized in detail. These first-time observations of cargo's rotational dynamics provide new insights on how kinesin and dynein motors take the cargo through the alternating stages of active directional transport and pause. To improve the localization precision of the SPT technique with DIC microscopy, a precise three-dimensional (3D) localization method of spherical gold nanoparticle probes using model-based correlation coefficient mapping was introduced. To accomplish this, a stack of sample images at different z-positions are acquired, and a 3D intensity profile of the probe serving as the model is used to map out the positions of nanoparticles in the sample. By using this model-based correlation imaging method, precise localization can be achieved in imaging techniques with complicated point spread functions (PSF) such as differential interference contrast (DIC) microscopy. The 3D superlocalization method was applied to tracking gold nanospheres during live endocytosis events. Finally, a novel dual-modality imaging technique has been developed to super-localize a single gold nanorod while providing its orientation and rotational information. The super-localization of the gold nanorod can be accomplished by curve fitting the modified bright-field images generated by one of the two beams laterally shifted by the first Nomarski prism in a DIC microscope. The orientation and rotational information is derived from the DIC images of gold nanorods. The new imaging setup has been applied to study the steric hindrance induced by relatively large cargos in the microtubule gliding assay and to track nanocargos in the crowded cellular environment.« less

Transverse-momentum and pseudorapidity distributions of charged hadrons in pp collisions at square root of s = 7 TeV.

PubMed

Khachatryan, V; Sirunyan, A M; Tumasyan, A; Adam, W; Bergauer, T; Dragicevic, M; Erö, J; Fabjan, C; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kiesenhofer, W; Krammer, M; Liko, D; Mikulec, I; Pernicka, M; Rohringer, H; Schöfbeck, R; Strauss, J; Taurok, A; Teischinger, F; Waltenberger, W; Walzel, G; Widl, E; Wulz, C-E; Mossolov, V; Shumeiko, N; Suarez Gonzalez, J; Benucci, L; Ceard, L; De Wolf, E A; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Roland, B; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; Devroede, O; Kalogeropoulos, A; Maes, J; Maes, M; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Gay, A P R; Hammad, G H; Marage, P E; Vander Velde, C; Vanlaer, P; Wickens, J; Costantini, S; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Walsh, S; Zaganidis, N; Basegmez, S; Bruno, G; Caudron, J; De Favereau De Jeneret, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Hollar, J; Lemaitre, V; Militaru, O; Ovyn, S; Pagano, D; Pin, A; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Caebergs, T; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; Da Costa, E M; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Torres Da Silva De Araujo, F; Dias, F A; Dias, M A F; Fernandez Perez Tomei, T R; Gregores, E M; Marinho, F; Novaes, S F; Padula, Sandra S; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dyulendarova, M; Hadjiiska, R; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Bian, J G; Chen, G M; Chen, H S; Jiang, C H; Liang, D; Liang, S; Wang, J; Wang, J; Wang, X; Wang, Z; Yang, M; Zang, J; 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Chang, Y W; Chao, Y; Chen, K F; Hou, W-S; Hsiung, Y; Kao, K Y; Lei, Y J; Lin, S W; Lu, R-S; Shiu, J G; Tzeng, Y M; Ueno, K; Wang, C C; Wang, M; Wei, J T; Adiguzel, A; Ayhan, A; Bakirci, M N; Cerci, S; Demir, Z; Dozen, C; Dumanoglu, I; Eskut, E; Girgis, S; Gökbulut, G; Güler, Y; Gurpinar, E; Hos, I; Kangal, E E; Karaman, T; Kayis Topaksu, A; Nart, A; Onengüt, G; Ozdemir, K; Ozturk, S; Polatöz, A; Sahin, O; Sengul, O; Sogut, K; Tali, B; Topakli, H; Uzun, D; Vergili, L N; Vergili, M; Zorbilmez, C; Akin, I V; Aliev, T; Bilmis, S; Deniz, M; Gamsizkan, H; Guler, A M; Ocalan, K; Ozpineci, A; Serin, M; Sever, R; Surat, U E; Zeyrek, M; Deliomeroglu, M; Demir, D; Gülmez, E; Halu, A; Isildak, B; Kaya, M; Kaya, O; Ozbek, M; Ozkorucuklu, S; Sonmez, N; Levchuk, L; Bell, P; Bostock, F; Brooke, J J; Cheng, T L; Cussans, D; Frazier, R; Goldstein, J; Hansen, M; Heath, G P; Heath, H F; Hill, C; Huckvale, B; Jackson, J; Kreczko, L; Mackay, C K; Metson, S; Newbold, D M; Nirunpong, K; Smith, V J; Ward, S; Basso, L; 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Chou, J P; Cutts, D; Esen, S; Heintz, U; Jabeen, S; Kukartsev, G; Landsberg, G; Narain, M; Nguyen, D; Speer, T; Tsang, K V; Borgia, M A; Breedon, R; Calderon De La Barca Sanchez, M; Cebra, D; Chertok, M; Conway, J; Cox, P T; Dolen, J; Erbacher, R; Friis, E; Ko, W; Kopecky, A; Lander, R; Liu, H; Maruyama, S; Miceli, T; Nikolic, M; Pellett, D; Robles, J; Schwarz, T; Searle, M; Smith, J; Squires, M; Tripathi, M; Vasquez Sierra, R; Veelken, C; Andreev, V; Arisaka, K; Cline, D; Cousins, R; Deisher, A; Erhan, S; Farrell, C; Felcini, M; Hauser, J; Ignatenko, M; Jarvis, C; Plager, C; Rakness, G; Schlein, P; Tucker, J; Valuev, V; Wallny, R; Babb, J; Clare, R; Ellison, J; Gary, J W; Hanson, G; Jeng, G Y; Kao, S C; Liu, F; Liu, H; Luthra, A; Nguyen, H; Pasztor, G; Satpathy, A; Shen, B C; Stringer, R; Sturdy, J; Sumowidagdo, S; Wilken, R; Wimpenny, S; Andrews, W; Branson, J G; Dusinberre, E; Evans, D; Golf, F; Holzner, A; Kelley, R; Lebourgeois, M; Letts, J; Mangano, B; Muelmenstaedt, J; Padhi, S; Palmer, C; Petrucciani, G; Pi, H; Pieri, M; Ranieri, R; Sani, M; Sharma, V; Simon, S; Tu, Y; Vartak, A; Würthwein, F; Yagil, A; Barge, D; Blume, M; Campagnari, C; D'Alfonso, M; Danielson, T; Garberson, J; Incandela, J; Justus, C; Kalavase, P; Koay, S A; Kovalskyi, D; Krutelyov, V; Lamb, J; Lowette, S; Pavlunin, V; Rebassoo, F; Ribnik, J; Richman, J; Rossin, R; Stuart, D; To, W; Vlimant, J R; Witherell, M; Bornheim, A; Bunn, J; Gataullin, M; Kcira, D; Litvine, V; Ma, Y; Newman, H B; Rogan, C; Shin, K; Timciuc, V; Veverka, J; Wilkinson, R; Yang, Y; Zhu, R Y; Akgun, B; Carroll, R; Ferguson, T; Jang, D W; Jun, S Y; Paulini, M; Russ, J; Terentyev, N; Vogel, H; Vorobiev, I; Cumalat, J P; Dinardo, M E; Drell, B R; Ford, W T; Heyburn, B; Luiggi Lopez, E; Nauenberg, U; Smith, J G; Stenson, K; Ulmer, K A; Wagner, S R; Zang, S L; Agostino, L; Alexander, J; Blekman, F; Chatterjee, A; Das, S; Eggert, N; Fields, L J; Gibbons, L K; Heltsley, B; Hopkins, W; Khukhunaishvili, A; Kreis, B; Kuznetsov, V; Kaufman, G Nicolas; Patterson, J R; Puigh, D; Riley, D; Ryd, A; Shi, X; Sun, W; Teo, W D; Thom, J; Thompson, J; Vaughan, J; Weng, Y; Wittich, P; Biselli, A; Cirino, G; Winn, D; Abdullin, S; Albrow, M; Anderson, J; Apollinari, G; Atac, M; Bakken, J A; Banerjee, S; Bauerdick, L A T; Beretvas, A; Berryhill, J; Bhat, P C; Bloch, I; Borcherding, F; Burkett, K; Butler, J N; Chetluru, V; Cheung, H W K; Chlebana, F; Cihangir, S; Demarteau, M; Eartly, D P; Elvira, V D; Fisk, I; Freeman, J; Gao, Y; Gottschalk, E; Green, D; Gutsche, O; Hahn, A; Hanlon, J; Harris, R M; James, E; Jensen, H; Johnson, M; Joshi, U; Khatiwada, R; Kilminster, B; Klima, B; Kousouris, K; Kunori, S; Kwan, S; Limon, P; Lipton, R; Lykken, J; Maeshima, K; Marraffino, J M; Mason, D; McBride, P; McCauley, T; Miao, T; Mishra, K; Mrenna, S; Musienko, Y; Newman-Holmes, C; O'Dell, V; Popescu, S; Pordes, R; Prokofyev, O; Saoulidou, N; Sexton-Kennedy, E; Sharma, S; Smith, R P; Soha, A; Spalding, W J; Spiegel, L; Tan, P; Taylor, L; Tkaczyk, S; Uplegger, L; Vaandering, E W; Vidal, R; Whitmore, J; Wu, W; Yumiceva, F; Yun, J C; Acosta, D; Avery, P; Bourilkov, D; Chen, M; Di Giovanni, G P; Dobur, D; Drozdetskiy, A; Field, R D; Fu, Y; Furic, I K; Gartner, J; Kim, B; Klimenko, S; Konigsberg, J; Korytov, A; Kotov, K; Kropivnitskaya, A; Kypreos, T; Matchev, K; Mitselmakher, G; Pakhotin, Y; Piedra Gomez, J; Prescott, C; Remington, R; Schmitt, M; Scurlock, B; Sellers, P; Wang, D; Yelton, J; Zakaria, M; Ceron, C; Gaultney, V; Kramer, L; Lebolo, L M; Linn, S; Markowitz, P; Martinez, G; Mesa, D; Rodriguez, J L; Adams, T; Askew, A; Chen, J; Diamond, B; Gleyzer, S V; Haas, J; Hagopian, S; Hagopian, V; Jenkins, M; Johnson, K F; Prosper, H; Sekmen, S; Veeraraghavan, V; Baarmand, M M; Guragain, S; Hohlmann, M; Kalakhety, H; Mermerkaya, H; Ralich, R; Vodopiyanov, I; Adams, M R; Anghel, I M; Apanasevich, L; Bazterra, V E; Betts, R R; Callner, J; Cavanaugh, R; Dragoiu, C; Garcia-Solis, E J; Gerber, C E; Hofman, D J; Khalatian, S; Lacroix, F; Shabalina, E; Smoron, A; Strom, D; Varelas, N; Akgun, U; Albayrak, E A; Bilki, B; Cankocak, K; Clarida, W; Duru, F; Lae, C K; McCliment, E; Merlo, J-P; Mestvirishvili, A; Moeller, A; Nachtman, J; Newsom, C R; Norbeck, E; Olson, J; Onel, Y; Ozok, F; Sen, S; Wetzel, J; Yetkin, T; Yi, K; Barnett, B A; Blumenfeld, B; Bonato, A; Eskew, C; Fehling, D; Giurgiu, G; Gritsan, A V; Guo, Z J; Hu, G; Maksimovic, P; Rappoccio, S; Swartz, M; Tran, N V; Whitbeck, A; Baringer, P; Bean, A; Benelli, G; Grachov, O; Murray, M; Radicci, V; Sanders, S; Wood, J S; Zhukova, V; Bandurin, D; Bolton, T; Chakaberia, I; Ivanov, A; Kaadze, K; Maravin, Y; Shrestha, S; Svintradze, I; Wan, Z; Gronberg, J; Lange, D; Wright, D; Baden, D; Boutemeur, M; Eno, S C; Ferencek, D; Hadley, N J; Kellogg, R G; Kirn, M; Mignerey, A; Rossato, K; Rumerio, P; Santanastasio, F; Skuja, A; Temple, J; Tonjes, M B; Tonwar, S C; Twedt, E; Alver, B; Bauer, G; Bendavid, J; Busza, W; Butz, E; Cali, I A; Chan, M; D'Enterria, D; Everaerts, P; Gomez Ceballos, G; Goncharov, M; Hahn, K A; Harris, P; Kim, Y; Klute, M; Lee, Y-J; Li, W; Loizides, C; Luckey, P D; Ma, T; Nahn, S; Paus, C; Roland, C; Roland, G; Rudolph, M; Stephans, G S F; Sumorok, K; Sung, K; Wenger, E A; Wyslouch, B; Xie, S; Yilmaz, Y; Yoon, A S; Zanetti, M; Cole, P; Cooper, S I; Cushman, P; Dahmes, B; De Benedetti, A; Dudero, P R; Franzoni, G; Haupt, J; Klapoetke, K; Kubota, Y; Mans, J; Petyt, D; Rekovic, V; Rusack, R; Sasseville, M; Singovsky, A; Cremaldi, L M; Godang, R; Kroeger, R; Perera, L; Rahmat, R; Sanders, D A; Sonnek, P; Summers, D; Bloom, K; Bose, S; Butt, J; Claes, D R; Dominguez, A; Eads, M; Keller, J; Kelly, T; Kravchenko, I; Lazo-Flores, J; Lundstedt, C; Malbouisson, H; Malik, S; Snow, G R; Baur, U; Iashvili, I; Kharchilava, A; Kumar, A; Smith, K; Strang, M; Zennamo, J; Alverson, G; Barberis, E; Baumgartel, D; Boeriu, O; Reucroft, S; Swain, J; Wood, D; Zhang, J; Anastassov, A; Kubik, A; Ofierzynski, R A; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolb, J; Kolberg, T; Lannon, K; Lynch, S; Marinelli, N; Morse, D M; Ruchti, R; Slaunwhite, J; Valls, N; Warchol, J; Wayne, M; Ziegler, J; Bylsma, B; Durkin, L S; Gu, J; Killewald, P; Ling, T Y; Williams, G; Adam, N; Berry, E; Elmer, P; Gerbaudo, D; Halyo, V; Hunt, A; Jones, J; Laird, E; Lopes Pegna, D; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Stickland, D; Tully, C; Werner, J S; Zuranski, A; Acosta, J G; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Zatzerklyaniy, A; Alagoz, E; Barnes, V E; Bolla, G; Borrello, L; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Potamianos, K; Shipsey, I; Silvers, D; Yoo, H D; Zablocki, J; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Morales, J; Padley, B P; Redjimi, R; Roberts, J; Betchart, B; Bodek, A; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Garcia-Bellido, A; Gotra, Y; Han, J; Harel, A; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Gershtein, Y; Gray, R; Halkiadakis, E; Hidas, D; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Eusebi, R; Gilmore, J; Gurrola, A; Kamon, T; Khotilovich, V; Montalvo, R; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Bardak, C; Damgov, J; Jeong, C; Kovitanggoon, K; Lee, S W; Mane, P; Roh, Y; Sill, A; Volobouev, I; Wigmans, R; Yazgan, E; Appelt, E; Brownson, E; Engh, D; Florez, C; Gabella, W; Johns, W; Kurt, P; Maguire, C; Melo, A; Sheldon, P; Velkovska, J; Arenton, M W; Balazs, M; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Milstène, C; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Dasu, S; Dutta, S; Efron, J; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Herndon, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Lomidze, D; Loveless, R; Mohapatra, A; Polese, G; Reeder, D; Savin, A; Smith, W H; Swanson, J; Weinberg, M

2010-07-09

Charged-hadron transverse-momentum and pseudorapidity distributions in proton-proton collisions at square root of s = 7  TeV are measured with the inner tracking system of the CMS detector at the LHC. The charged-hadron yield is obtained by counting the number of reconstructed hits, hit pairs, and fully reconstructed charged-particle tracks. The combination of the three methods gives a charged-particle multiplicity per unit of pseudorapidity dN(ch)/dη|(|η|<0.5) = 5.78 ± 0.01(stat) ± 0.23(syst) for non-single-diffractive events, higher than predicted by commonly used models. The relative increase in charged-particle multiplicity from square root of s = 0.9 to 7 TeV is [66.1 ± 1.0(stat) ± 4.2(syst)]%. The mean transverse momentum is measured to be 0.545 ± 0.005(stat) ± 0.015(syst)  GeV/c. The results are compared with similar measurements at lower energies.

TH-A-19A-04: Latent Uncertainties and Performance of a GPU-Implemented Pre-Calculated Track Monte Carlo Method

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

Renaud, M; Seuntjens, J; Roberge, D

Purpose: Assessing the performance and uncertainty of a pre-calculated Monte Carlo (PMC) algorithm for proton and electron transport running on graphics processing units (GPU). While PMC methods have been described in the past, an explicit quantification of the latent uncertainty arising from recycling a limited number of tracks in the pre-generated track bank is missing from the literature. With a proper uncertainty analysis, an optimal pre-generated track bank size can be selected for a desired dose calculation uncertainty. Methods: Particle tracks were pre-generated for electrons and protons using EGSnrc and GEANT4, respectively. The PMC algorithm for track transport was implementedmore » on the CUDA programming framework. GPU-PMC dose distributions were compared to benchmark dose distributions simulated using general-purpose MC codes in the same conditions. A latent uncertainty analysis was performed by comparing GPUPMC dose values to a “ground truth” benchmark while varying the track bank size and primary particle histories. Results: GPU-PMC dose distributions and benchmark doses were within 1% of each other in voxels with dose greater than 50% of Dmax. In proton calculations, a submillimeter distance-to-agreement error was observed at the Bragg Peak. Latent uncertainty followed a Poisson distribution with the number of tracks per energy (TPE) and a track bank of 20,000 TPE produced a latent uncertainty of approximately 1%. Efficiency analysis showed a 937× and 508× gain over a single processor core running DOSXYZnrc for 16 MeV electrons in water and bone, respectively. Conclusion: The GPU-PMC method can calculate dose distributions for electrons and protons to a statistical uncertainty below 1%. The track bank size necessary to achieve an optimal efficiency can be tuned based on the desired uncertainty. Coupled with a model to calculate dose contributions from uncharged particles, GPU-PMC is a candidate for inverse planning of modulated electron radiotherapy and scanned proton beams. This work was supported in part by FRSQ-MSSS (Grant No. 22090), NSERC RG (Grant No. 432290) and CIHR MOP (Grant No. MOP-211360)« less

Impact of agglomeration state of nano- and submicron sized gold particles on pulmonary inflammation

PubMed Central

2010-01-01

Background Nanoparticle (NP) toxicity testing comes with many challenges. Characterization of the test substance is of crucial importance and in the case of NPs, agglomeration/aggregation state in physiological media needs to be considered. In this study, we have addressed the effect of agglomerated versus single particle suspensions of nano- and submicron sized gold on the inflammatory response in the lung. Rats were exposed to a single dose of 1.6 mg/kg body weight (bw) of spherical gold particles with geometric diameters of 50 nm or 250 nm diluted either by ultrapure water or by adding phosphate buffered saline (PBS). A single dose of 1.6 mg/kg bw DQ12 quartz was used as a positive control for pulmonary inflammation. Extensive characterization of the particle suspensions has been performed by determining the zetapotential, pH, gold concentration and particle size distribution. Primary particle size and particle purity has been verified using transmission electron microscopy (TEM) techniques. Pulmonary inflammation (total cell number, differential cell count and pro-inflammatory cytokines), cell damage (total protein and albumin) and cytotoxicity (alkaline phosphatase and lactate dehydrogenase) were determined in bronchoalveolar lavage fluid (BALF) and acute systemic effects in blood (total cell number, differential cell counts, fibrinogen and C-reactive protein) 3 and 24 hours post exposure. Uptake of gold particles in alveolar macrophages has been determined by TEM. Results Particles diluted in ultrapure water are well dispersed, while agglomerates are formed when diluting in PBS. The particle size of the 50 nm particles was confirmed, while the 250 nm particles appear to be 200 nm using tracking analysis and 210 nm using TEM. No major differences in pulmonary and systemic toxicity markers were observed after instillation of agglomerated versus single gold particles of different sizes. Both agglomerated as well as single nanoparticles were taken up by macrophages. Conclusion Primary particle size, gold concentration and particle purity are important features to check, since these characteristics may deviate from the manufacturer's description. Suspensions of well dispersed 50 nm and 250 nm particles as well as their agglomerates produced very mild pulmonary inflammation at the same mass based dose. We conclude that single 50 nm gold particles do not pose a greater acute hazard than their agglomerates or slightly larger gold particles when using pulmonary inflammation as a marker for toxicity. PMID:21126342

Dose equivalent neutron dosimeter

DOEpatents

Griffith, Richard V.; Hankins, Dale E.; Tomasino, Luigi; Gomaa, Mohamed A. M.

1983-01-01

A neutron dosimeter is disclosed which provides a single measurements indicating the amount of potential biological damage resulting from the neutron exposure of the wearer, for a wide range of neutron energies. The dosimeter includes a detecting sheet of track etch detecting material such as a carbonate plastic, for detecting higher energy neutrons, and a radiator layer containing conversion material such as .sup.6 Li and .sup.10 B lying adjacent to the detecting sheet for converting moderate energy neutrons to alpha particles that produce tracks in the adjacent detecting sheet. The density of conversion material in the radiator layer is of an amount which is chosen so that the density of tracks produced in the detecting sheet is proportional to the biological damage done by neutrons, regardless of whether the tracks are produced as the result of moderate energy neutrons striking the radiator layer or as the result of higher energy neutrons striking the sheet of track etch material.

Adaptation of reference volumes for correlation-based digital holographic particle tracking

NASA Astrophysics Data System (ADS)

Hesseling, Christina; Peinke, Joachim; Gülker, Gerd

2018-04-01

Numerically reconstructed reference volumes tailored to particle images are used for particle position detection by means of three-dimensional correlation. After a first tracking of these positions, the experimentally recorded particle images are retrieved as a posteriori knowledge about the particle images in the system. This knowledge is used for a further refinement of the detected positions. A transparent description of the individual algorithm steps including the results retrieved with experimental data complete the paper. The work employs extraordinarily small particles, smaller than the pixel pitch of the camera sensor. It is the first approach known to the authors that combines numerical knowledge about particle images and particle images retrieved from the experimental system to an iterative particle tracking approach for digital holographic particle tracking velocimetry.

Clogging in constricted suspension flows

NASA Astrophysics Data System (ADS)

Marin, Alvaro; Lhuissier, Henri; Rossi, Massimiliano; Kähler, Christian J.

2018-02-01

The flow of a charged-stabilized suspension through a single constricted channel is studied experimentally by tracking the particles individually. Surprisingly, the behavior is found to be qualitatively similar to that of inertial dry granular systems: For small values of the neck-to-particle size ratio (D /d <3 ), clogs form randomly as arches of the particle span the constriction. The statistics of the clogging events are Poissonian as reported for granular systems and agree for moderate particle volume fraction (ϕ ≈20 % ) with a simple stochastic model for the number of particles at the neck. For larger neck sizes (D /d >3 ), even at the largest ϕ (≈60 %) achievable in the experiments, an uninterrupted particle flow is observed, which resembles that of an hourglass. This particularly small value of D /d (≃3 ) at the transition to a practically uninterrupted flow is attributed to the low effective friction between the particles, achieved by the particle's functionalization and lubrication.

A Quantitative Comparison of Single-Dye Tracking Analysis Tools Using Monte Carlo Simulations

PubMed Central

McColl, James; Irvine, Kate L.; Davis, Simon J.; Gay, Nicholas J.; Bryant, Clare E.; Klenerman, David

2013-01-01

Single-particle tracking (SPT) is widely used to study processes from membrane receptor organization to the dynamics of RNAs in living cells. While single-dye labeling strategies have the benefit of being minimally invasive, this comes at the expense of data quality; typically a data set of short trajectories is obtained and analyzed by means of the mean square displacements (MSD) or the distribution of the particles’ displacements in a set time interval (jump distance, JD). To evaluate the applicability of both approaches, a quantitative comparison of both methods under typically encountered experimental conditions is necessary. Here we use Monte Carlo simulations to systematically compare the accuracy of diffusion coefficients (D-values) obtained for three cases: one population of diffusing species, two populations with different D-values, and a population switching between two D-values. For the first case we find that the MSD gives more or equally accurate results than the JD analysis (relative errors of D-values <6%). If two diffusing species are present or a particle undergoes a motion change, the JD analysis successfully distinguishes both species (relative error <5%). Finally we apply the JD analysis to investigate the motion of endogenous LPS receptors in live macrophages before and after treatment with methyl-β-cyclodextrin and latrunculin B. PMID:23737978

Single Particle Tracking reveals two distinct environments for CD4 receptors at the surface of living T lymphocytes

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

Mascalchi, Patrice; Lamort, Anne Sophie; Salome, Laurence

2012-01-06

Highlights: Black-Right-Pointing-Pointer We studied the diffusion of single CD4 receptors on living lymphocytes. Black-Right-Pointing-Pointer This study reveals that CD4 receptors have either a random or confined diffusion. Black-Right-Pointing-Pointer The dynamics of unconfined CD4 receptors was accelerated by a temperature raise. Black-Right-Pointing-Pointer The dynamics of confined CD4 receptors was unchanged by a temperature raise. Black-Right-Pointing-Pointer Our results suggest the existence of two different environments for CD4 receptors. -- Abstract: We investigated the lateral diffusion of the HIV receptor CD4 at the surface of T lymphocytes at 20 Degree-Sign C and 37 Degree-Sign C by Single Particle Tracking using Quantum Dots. Wemore » found that the receptors presented two major distinct behaviors that were not equally affected by temperature changes. About half of the receptors showed a random diffusion with a diffusion coefficient increasing upon raising the temperature. The other half of the receptors was permanently or transiently confined with unchanged dynamics on raising the temperature. These observations suggest that two distinct subpopulations of CD4 receptors with different environments are present at the surface of living T lymphocytes.« less

Characterization of the diffusion of epidermal growth factor receptor clusters by single particle tracking.

PubMed

Boggara, Mohan; Athmakuri, Krishna; Srivastava, Sunit; Cole, Richard; Kane, Ravi S

2013-02-01

A number of studies have shown that receptors of the epidermal growth factor receptor family (ErbBs) exist as higher-order oligomers (clusters) in cell membranes in addition to their monomeric and dimeric forms. Characterizing the lateral diffusion of such clusters may provide insights into their dynamics and help elucidate their functional relevance. To that end, we used single particle tracking to study the diffusion of clusters of the epidermal growth factor (EGF) receptor (EGFR; ErbB1) containing bound fluorescently-labeled ligand, EGF. EGFR clusters had a median diffusivity of 6.8×10(-11)cm(2)/s and were found to exhibit different modes of transport (immobile, simple, confined, and directed) similar to that previously reported for single EGFR molecules. Disruption of actin filaments increased the median diffusivity of EGFR clusters to 10.3×10(-11)cm(2)/s, while preserving the different modes of diffusion. Interestingly, disruption of microtubules rendered EGFR clusters nearly immobile. Our data suggests that microtubules may play an important role in the diffusion of EGFR clusters either directly or perhaps indirectly via other mechanisms. To our knowledge, this is the first report probing the effect of the cytoskeleton on the diffusion of EGFR clusters in the membranes of live cells. Copyright © 2012 Elsevier B.V. All rights reserved.

Electrodynamic balance-mass spectrometry of single particles as a new platform for atmospheric chemistry research

NASA Astrophysics Data System (ADS)

Birdsall, Adam W.; Krieger, Ulrich K.; Keutsch, Frank N.

2018-01-01

New analytical techniques are needed to improve our understanding of the intertwined physical and chemical processes that affect the composition of aerosol particles in the Earth's atmosphere, such as gas-particle partitioning and homogenous or heterogeneous chemistry, and their ultimate relation to air quality and climate. We describe a new laboratory setup that couples an electrodynamic balance (EDB) to a mass spectrometer (MS). The EDB stores a single laboratory-generated particle in an electric field under atmospheric conditions for an arbitrarily long length of time. The particle is then transferred via gas flow to an ionization region that vaporizes and ionizes the analyte molecules before MS measurement. We demonstrate the feasibility of the technique by tracking evaporation of polyethylene glycol molecules and finding agreement with a kinetic model. Fitting data to the kinetic model also allows determination of vapor pressures to within a factor of 2. This EDB-MS system can be used to study fundamental chemical and physical processes involving particles that are difficult to isolate and study with other techniques. The results of such measurements can be used to improve our understanding of atmospheric particles.

Nanoscale Rheology and Anisotropic Diffusion Using Single Gold Nanorod Probes

NASA Astrophysics Data System (ADS)

Molaei, Mehdi; Atefi, Ehsan; Crocker, John C.

2018-03-01

The complex rotational and translational Brownian motion of anisotropic particles depends on their shape and the viscoelasticity of their surroundings. Because of their strong optical scattering and chemical versatility, gold nanorods would seem to provide the ultimate probes of rheology at the nanoscale, but the suitably accurate orientational tracking required to compute rheology has not been demonstrated. Here we image single gold nanorods with a laser-illuminated dark-field microscope and use optical polarization to determine their three-dimensional orientation to better than one degree. We convert the rotational diffusion of single nanorods in viscoelastic polyethylene glycol solutions to rheology and obtain excellent agreement with bulk measurements. Extensions of earlier models of anisotropic translational diffusion to three dimensions and viscoelastic fluids give excellent agreement with the observed motion of single nanorods. We find that nanorod tracking provides a uniquely capable approach to microrheology and provides a powerful tool for probing nanoscale dynamics and structure in a range of soft materials.

Radiation-driven rotational motion of nanoparticles

DOE PAGES

Liang, Mengning; Harder, Ross; Robinson, Ian

2018-04-25

Focused synchrotron beams can influence a studied sample via heating, or radiation pressure effects due to intensity gradients. The high angular sensitivity of rotational X-ray tracking (RXT) of crystalline particles via their Bragg reflections can detect extremely small forces such as those caused by field gradients. By tracking the rotational motion of single crystal nanoparticles embedded in a viscous or viscoelastic medium, we observed the effects of heating in a uniform gradient beam and radiation pressure in a Gaussian profile beam. Heating of a few degrees Celsius was measured for 42μm crystals in glycerol and angular velocities of 10 -6rad/smore » due to torques of 10 - 24N∙m were measured for 340nm crystals in a colloidal gel matrix. These results show the ability to quantify small forces using rotation motion of tracer particles.« less

Radiation-driven rotational motion of nanoparticles

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

Liang, Mengning; Harder, Ross; Robinson, Ian

Focused synchrotron beams can influence a studied sample via heating, or radiation pressure effects due to intensity gradients. The high angular sensitivity of rotational X-ray tracking (RXT) of crystalline particles via their Bragg reflections can detect extremely small forces such as those caused by field gradients. By tracking the rotational motion of single crystal nanoparticles embedded in a viscous or viscoelastic medium, we observed the effects of heating in a uniform gradient beam and radiation pressure in a Gaussian profile beam. Heating of a few degrees Celsius was measured for 42μm crystals in glycerol and angular velocities of 10 -6rad/smore » due to torques of 10 - 24N∙m were measured for 340nm crystals in a colloidal gel matrix. These results show the ability to quantify small forces using rotation motion of tracer particles.« less

Particle track identification: application of a new technique to apollo helmets.

PubMed

Fleischer, R L; Hart, H R; Giard, W R

1970-12-11

The Apollo helmets are being used to record the dose of heavy particles to which astronauts are exposed on space missions. An improved method for examining and identifying the etched tracks of heavy charged particles consists of replicating tracks and measuring the etching rate as a function of position along the track. Tracks have been observed in Apollo helmets that correspond to ionized atoms heavier than iron.

Multiscale Airflow Model and Aerosol Deposition in Healthy and Emphysematous Rat Lungs

NASA Astrophysics Data System (ADS)

Oakes, Jessica; Marsden, Alison; Grandmont, Celine; Darquenne, Chantal; Vignon-Clementel, Irene

2012-11-01

The fate of aerosol particles in healthy and emphysematic lungs is needed to determine the toxic or therapeutic effects of inhalable particles. In this study we used a multiscale numerical model that couples a 0D resistance and capacitance model to 3D airways generated from MR images. Airflow simulations were performed using an in-house 3D finite element solver (SimVascular, simtk.org). Seven simulations were performed; 1 healthy, 1 uniform emphysema and 5 different cases of heterogeneous emphysema. In the heterogeneous emphysema cases the disease was confined to a single lobe. As a post processing step, 1 micron diameter particles were tracked in the flow field using Lagrangian particle tracking. The simulation results showed that the inhaled flow distribution was equal for the healthy and uniform emphysema cases. However, in the heterogeneous emphysema cases the delivery of inhaled air was larger in the diseased lobe. Additionally, there was an increase in delivery of aerosol particles to the diseased lobe. This suggests that as the therapeutic particles would reach the diseased areas of the lung, while toxic particles would increasingly harm the lung. The 3D-0D model described here is the first of its kind to be used to study healthy and emphysematic lungs. NSF Graduate Fellowship (Oakes), Burroughs Wellcome Fund (Marsden, Oakes) 1R21HL087805-02 from NHLBI at NIH, INRIA Team Grant.

Dual-color multiple-particle tracking at 50-nm localization and over 100-µm range in 3D with temporal focusing two-photon microscopy

PubMed Central

Ding, Yu; Li, Chunqiang

2016-01-01

Nanoscale particle tracking in three dimensions is crucial to directly observe dynamics of molecules and nanoparticles in living cells. Here we present a three-dimensional particle tracking method based on temporally focused two-photon excitation. Multiple particles are imaged at 30 frames/s in volume up to 180 × 180 × 100 µm3. The spatial localization precision can reach 50 nm. We demonstrate its capability of tracking fast swimming microbes at speed of ~200 µm/s. Two-photon dual-color tracking is achieved by simultaneously exciting two kinds of fluorescent beads at 800 nm to demonstrate its potential in molecular interaction studies. Our method provides a simple wide-field fluorescence imaging approach for deep multiple-particle tracking. PMID:27867724

FAST TRACK COMMUNICATION: Suppressing anomalous diffusion by cooperation

NASA Astrophysics Data System (ADS)

Dybiec, Bartłomiej

2010-08-01

Within a continuous time random walk scenario we consider a motion of a complex of particles which moves coherently. The motion of every particle is characterized by the waiting time and jump length distributions which are of the power-law type. Due to the interactions between particles it is assumed that the waiting time is adjusted to the shortest or to the longest waiting time. Analogously, the jump length is adjusted to the shortest or to the longest jump length. We show that adjustment to the shortest waiting time can suppress the subdiffusive behavior even in situations when the exponent characterizing the waiting time distribution assures subdiffusive motion of a single particle. Finally, we demonstrate that the characteristic of the motion depends on the number of particles building a complex.

Intracavity optical trapping with Ytterbium doped fiber ring laser

NASA Astrophysics Data System (ADS)

Sayed, Rania; Kalantarifard, Fatemeh; Elahi, Parviz; Ilday, F. Omer; Volpe, Giovanni; Maragò, Onofrio M.

2013-09-01

We propose a novel approach for trapping micron-sized particles and living cells based on optical feedback. This approach can be implemented at low numerical aperture (NA=0.5, 20X) and long working distance. In this configuration, an optical tweezers is constructed inside a ring cavity fiber laser and the optical feedback in the ring cavity is controlled by the light scattered from a trapped particle. In particular, once the particle is trapped, the laser operation, optical feedback and intracavity power are affected by the particle motion. We demonstrate that using this configuration is possible to stably hold micron-sized particles and single living cells in the focal spot of the laser beam. The calibration of the optical forces is achieved by tracking the Brownian motion of a trapped particle or cell and analysing its position distribution.

Interaction of Burning Metal Particles

NASA Technical Reports Server (NTRS)

Dreizin, Edward L.; Berman, Charles H.; Hoffmann, Vern K.

1999-01-01

Physical characteristics of the combustion of metal particle groups have been addressed in this research. The combustion behavior and interaction effects of multiple metal particles has been studied using a microgravity environment, which presents a unique opportunity to create an "aerosol" consisting of relatively large particles, i.e., 50-300 m diameter. Combustion behavior of such an aerosol could be examined using methods adopted from well-developed single particle combustion research. The experiment included fluidizing relatively large (order of 100 m diameter) uniform metal particles under microgravity and igniting such an "aerosol" using a hot wire igniter. The flame propagation and details of individual particle combustion and particle interaction have been studied using a high speed movie and video-imaging with cameras coupled with microscope lenses to resolve individual particles. Interference filters were used to separate characteristic metal and metal oxide radiation bands from the thermal black body radiation. Recorded flame images were digitized and various image processing techniques including flame position tracking, color separation, and pixel by pixel image comparison were employed to understand the processes occurring in the burning aerosol. The development of individual particle flames, merging or separation, and extinguishment as well as induced particle motion have been analyzed to identify the mechanisms governing these processes. Size distribution, morphology, and elemental compositions of combustion products were characterized and used to link the observed in this project aerosol combustion phenomena with the recently expanded mechanism of single metal particle combustion.

Method and system for detecting polygon boundaries of structures in images as particle tracks through fields of corners and pixel gradients

DOEpatents

Paglieroni, David W [Pleasanton, CA; Manay, Siddharth [Livermore, CA

2011-12-20

A stochastic method and system for detecting polygon structures in images, by detecting a set of best matching corners of predetermined acuteness .alpha. of a polygon model from a set of similarity scores based on GDM features of corners, and tracking polygon boundaries as particle tracks using a sequential Monte Carlo approach. The tracking involves initializing polygon boundary tracking by selecting pairs of corners from the set of best matching corners to define a first side of a corresponding polygon boundary; tracking all intermediate sides of the polygon boundaries using a particle filter, and terminating polygon boundary tracking by determining the last side of the tracked polygon boundaries to close the polygon boundaries. The particle tracks are then blended to determine polygon matches, which may be made available, such as to a user, for ranking and inspection.

Determination of time zero from a charged particle detector

DOEpatents

Green, Jesse Andrew [Los Alamos, NM

2011-03-15

A method, system and computer program is used to determine a linear track having a good fit to a most likely or expected path of charged particle passing through a charged particle detector having a plurality of drift cells. Hit signals from the charged particle detector are associated with a particular charged particle track. An initial estimate of time zero is made from these hit signals and linear tracks are then fit to drift radii for each particular time-zero estimate. The linear track having the best fit is then searched and selected and errors in fit and tracking parameters computed. The use of large and expensive fast detectors needed to time zero in the charged particle detectors can be avoided by adopting this method and system.

Background-Free 3D Nanometric Localization and Sub-nm Asymmetry Detection of Single Plasmonic Nanoparticles by Four-Wave Mixing Interferometry with Optical Vortices

NASA Astrophysics Data System (ADS)

Zoriniants, George; Masia, Francesco; Giannakopoulou, Naya; Langbein, Wolfgang; Borri, Paola

2017-10-01

Single nanoparticle tracking using optical microscopy is a powerful technique with many applications in biology, chemistry, and material sciences. Despite significant advances, localizing objects with nanometric position precision in a scattering environment remains challenging. Applied methods to achieve contrast are dominantly fluorescence based, with fundamental limits in the emitted photon fluxes arising from the excited-state lifetime as well as photobleaching. Here, we show a new four-wave-mixing interferometry technique, whereby the position of a single nonfluorescing gold nanoparticle of 25-nm radius is determined with 16 nm precision in plane and 3 nm axially from rapid single-point measurements at 1-ms acquisition time by exploiting optical vortices. The precision in plane is consistent with the photon shot-noise, while axially it is limited by the nano-positioning sample stage, with an estimated photon shot-noise limit of 0.5 nm. The detection is background-free even inside biological cells. The technique is also uniquely sensitive to particle asymmetries of only 0.5% ellipticity, corresponding to a single atomic layer of gold, as well as particle orientation. This method opens new ways of unraveling single-particle trafficking within complex 3D architectures.

On charged particle tracks in cellulose nitrate and Lexan

NASA Technical Reports Server (NTRS)

Benton, E. V.; Henke, R. P.

1972-01-01

Investigations were performed aimed at developing plastic nuclear track detectors into quantitative tools for recording and measuring multicharged, heavy particles. Accurate track etch rate measurements as a function of LET were performed for cellulose nitrate and Lexan plastic detectors. This was done using a variety of incident charged particle types and energies. The effect of aging of latent tracks in Lexan in different gaseous atmospheres was investigated. Range distributions of high energy N-14 particle bevatron beams in nuclear emulsion were measured. Investigation of charge resolution and Bragg peak measurements were carried out using plastic nuclear track detectors.

Material-specific detection and classification of single nanoparticles

PubMed Central

Person, Steven; Deutsch, Bradley; Mitra, Anirban; Novotny, Lukas

2010-01-01

Detection and classification of nanoparticles is important for environmental monitoring, contamination mitigation, biological label tracking, and bio-defense. Detection techniques involve a trade-off between sensitivity, discrimination, and speed. This paper presents a material-specific dual-color common-path interferometric detection system. Two wavelengths are simultaneously used to discriminate between 60 nm silver and 80 nm diameter gold particles in solution with a detection time of τ ≈ 1 ms. The detection technique is applicable to situations where both particle size and material are of interest. PMID:21142033

High-spatial-resolution mapping of catalytic reactions on single particles

DOE PAGES

Wu, Chung-Yeh; Wolf, William J.; Levartovsky, Yehonatan; ...

2017-01-26

We report the critical role in surface reactions and heterogeneous catalysis of metal atoms with low coordination numbers, such as found at atomic steps and surface defects, is firmly established. But despite the growing availability of tools that enable detailed in situ characterization, so far it has not been possible to document this role directly. Surface properties can be mapped with high spatial resolution, and catalytic conversion can be tracked with a clear chemical signature; however, the combination of the two, which would enable high-spatial-resolution detection of reactions on catalytic surfaces, has rarely been achieved. Single-molecule fluorescence spectroscopy has beenmore » used to image and characterize single turnover sites at catalytic surfaces, but is restricted to reactions that generate highly fluorescing product molecules. Herein the chemical conversion of N-heterocyclic carbene molecules attached to catalytic particles is mapped using synchrotron-radiation-based infrared nanospectroscopy with a spatial resolution of 25 nanometres, which enabled particle regions that differ in reactivity to be distinguished. Lastly, these observations demonstrate that, compared to the flat regions on top of the particles, the peripheries of the particles-which contain metal atoms with low coordination numbers-are more active in catalysing oxidation and reduction of chemically active groups in surface-anchored N-heterocyclic carbene molecules.« less

Three-dimensional spatiotemporal tracking of fluorine-18 radiolabeled yeast cells via positron emission particle tracking

DOE PAGES

Langford, Seth T.; Wiggins, Cody S.; Santos, Roque; ...

2017-07-06

A method for Positron Emission Particle Tracking (PEPT) based on optical feature point identification techniques is demonstrated for use in low activity tracking experiments. Furthermore, a population of yeast cells of approximately 125,000 members is activated to roughly 55 Bq/cell by 18F uptake. An in vitro particle tracking experiment is performed with nearly 20 of these cells after decay to 32 Bq/cell. These cells are successfully identified and tracked simultaneously in this experiment. Our work extends the applicability of PEPT as a cell tracking method by allowing a number of cells to be tracked together, and demonstrating tracking for verymore » low activity tracers.« less

Three-dimensional spatiotemporal tracking of fluorine-18 radiolabeled yeast cells via positron emission particle tracking

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

Langford, Seth T.; Wiggins, Cody S.; Santos, Roque

A method for Positron Emission Particle Tracking (PEPT) based on optical feature point identification techniques is demonstrated for use in low activity tracking experiments. Furthermore, a population of yeast cells of approximately 125,000 members is activated to roughly 55 Bq/cell by 18F uptake. An in vitro particle tracking experiment is performed with nearly 20 of these cells after decay to 32 Bq/cell. These cells are successfully identified and tracked simultaneously in this experiment. Our work extends the applicability of PEPT as a cell tracking method by allowing a number of cells to be tracked together, and demonstrating tracking for verymore » low activity tracers.« less

Shape Evolution and Single Particle Luminescence of Organometal Halide Perovskite Nanocrystals

DOE PAGES

Zhu, Feng; Men, Long; Guo, Yijun; ...

2015-02-09

Organometallic halide perovskites CH 3NH 3PbX 3 (X = I, Br, Cl) have quickly become one of the most promising semiconductors for solar cells, with photovoltaics made of these materials reaching power conversion efficiencies of near 20%. Improving our ability to harness the full potential of organometal halide perovskites will require more controllable syntheses that permit a detailed understanding of their fundamental chemistry and photophysics. In our manuscript, we systematically synthesize CH 3NH 3PbX 3 (X = I, Br) nanocrystals with different morphologies (dots, rods, plates or sheets) by using different solvents and capping ligands. CH 3NH 3PbX 3 nanowiresmore » and nanorods capped with octylammonium halides show relatively higher photoluminescence (PL) quantum yields and long PL lifetimes. CH 3NH 3PbI 3 nanowires monitored at the single particle level show shape-correlated PL emission across whole particles, with little photobleaching observed and very few off periods. Our work highlights the potential of low-dimensional organometal halide perovskite semiconductors in constructing new porous and nanostructured solar cell architectures, as well as in applying these materials to other fields such as light-emitting devices and single particle imaging and tracking.« less

Tracking Algorithm of Multiple Pedestrians Based on Particle Filters in Video Sequences

PubMed Central

Liu, Yun; Wang, Chuanxu; Zhang, Shujun; Cui, Xuehong

2016-01-01

Pedestrian tracking is a critical problem in the field of computer vision. Particle filters have been proven to be very useful in pedestrian tracking for nonlinear and non-Gaussian estimation problems. However, pedestrian tracking in complex environment is still facing many problems due to changes of pedestrian postures and scale, moving background, mutual occlusion, and presence of pedestrian. To surmount these difficulties, this paper presents tracking algorithm of multiple pedestrians based on particle filters in video sequences. The algorithm acquires confidence value of the object and the background through extracting a priori knowledge thus to achieve multipedestrian detection; it adopts color and texture features into particle filter to get better observation results and then automatically adjusts weight value of each feature according to current tracking environment. During the process of tracking, the algorithm processes severe occlusion condition to prevent drift and loss phenomena caused by object occlusion and associates detection results with particle state to propose discriminated method for object disappearance and emergence thus to achieve robust tracking of multiple pedestrians. Experimental verification and analysis in video sequences demonstrate that proposed algorithm improves the tracking performance and has better tracking results. PMID:27847514

Track reconstruction at LHC as a collaborative data challenge use case with RAMP

NASA Astrophysics Data System (ADS)

Amrouche, Sabrina; Braun, Nils; Calafiura, Paolo; Farrell, Steven; Gemmler, Jochen; Germain, Cécile; Gligorov, Vladimir Vava; Golling, Tobias; Gray, Heather; Guyon, Isabelle; Hushchyn, Mikhail; Innocente, Vincenzo; Kégl, Balázs; Neuhaus, Sara; Rousseau, David; Salzburger, Andreas; Ustyuzhanin, Andrei; Vlimant, Jean-Roch; Wessel, Christian; Yilmaz, Yetkin

2017-08-01

Charged particle track reconstruction is a major component of data-processing in high-energy physics experiments such as those at the Large Hadron Collider (LHC), and is foreseen to become more and more challenging with higher collision rates. A simplified two-dimensional version of the track reconstruction problem is set up on a collaborative platform, RAMP, in order for the developers to prototype and test new ideas. A small-scale competition was held during the Connecting The Dots / Intelligent Trackers 2017 (CTDWIT 2017) workshop. Despite the short time scale, a number of different approaches have been developed and compared along a single score metric, which was kept generic enough to accommodate a summarized performance in terms of both efficiency and fake rates.

Exploring transduction mechanisms of protein transduction domains (PTDs) in living cells utilizing single-quantum dot tracking (SQT) technology.

PubMed

Suzuki, Yasuhiro

2012-01-01

Specific protein domains known as protein transduction domains (PTDs) can permeate cell membranes and deliver proteins or bioactive materials into living cells. Various approaches have been applied for improving their transduction efficacy. It is, therefore, crucial to clarify the entry mechanisms and to identify the rate-limiting steps. Because of technical limitations for imaging PTD behavior on cells with conventional fluorescent-dyes, how PTDs enter the cells has been a topic of much debate. Utilizing quantum dots (QDs), we recently tracked the behavior of PTD that was derived from HIV-1 Tat (TatP) in living cells at the single-molecule level with 7-nm special precision. In this review article, we initially summarize the controversy on TatP entry mechanisms; thereafter, we will focus on our recent findings on single-TatP-QD tracking (SQT), to identify the major sequential steps of intracellular delivery in living cells and to discuss how SQT can easily provide direct information on TatP entry mechanisms. As a primer for SQT study, we also discuss the latest findings on single particle tracking of various molecules on the plasma membrane. Finally, we discuss the problems of QDs and the challenges for the future in utilizing currently available QD probes for SQT. In conclusion, direct identification of the rate-limiting steps of PTD entry with SQT should dramatically improve the methods for enhancing transduction efficiency.

Dissection of molecular assembly dynamics by tracking orientation and position of single molecules in live cells

PubMed Central

McQuilken, Molly; La Riviere, Patrick J.; Occhipinti, Patricia; Verma, Amitabh; Oldenbourg, Rudolf; Gladfelter, Amy S.; Tani, Tomomi

2016-01-01

Regulation of order, such as orientation and conformation, drives the function of most molecular assemblies in living cells but remains difficult to measure accurately through space and time. We built an instantaneous fluorescence polarization microscope, which simultaneously images position and orientation of fluorophores in living cells with single-molecule sensitivity and a time resolution of 100 ms. We developed image acquisition and analysis methods to track single particles that interact with higher-order assemblies of molecules. We tracked the fluctuations in position and orientation of molecules from the level of an ensemble of fluorophores down to single fluorophores. We tested our system in vitro using fluorescently labeled DNA and F-actin, in which the ensemble orientation of polarized fluorescence is known. We then tracked the orientation of sparsely labeled F-actin network at the leading edge of migrating human keratinocytes, revealing the anisotropic distribution of actin filaments relative to the local retrograde flow of the F-actin network. Additionally, we analyzed the position and orientation of septin-GFP molecules incorporated in septin bundles in growing hyphae of a filamentous fungus. Our data indicate that septin-GFP molecules undergo positional fluctuations within ∼350 nm of the binding site and angular fluctuations within ∼30° of the central orientation of the bundle. By reporting position and orientation of molecules while they form dynamic higher-order structures, our approach can provide insights into how micrometer-scale ordered assemblies emerge from nanoscale molecules in living cells. PMID:27679846

Inferring diffusion in single live cells at the single-molecule level

PubMed Central

Robson, Alex; Burrage, Kevin; Leake, Mark C.

2013-01-01

The movement of molecules inside living cells is a fundamental feature of biological processes. The ability to both observe and analyse the details of molecular diffusion in vivo at the single-molecule and single-cell level can add significant insight into understanding molecular architectures of diffusing molecules and the nanoscale environment in which the molecules diffuse. The tool of choice for monitoring dynamic molecular localization in live cells is fluorescence microscopy, especially so combining total internal reflection fluorescence with the use of fluorescent protein (FP) reporters in offering exceptional imaging contrast for dynamic processes in the cell membrane under relatively physiological conditions compared with competing single-molecule techniques. There exist several different complex modes of diffusion, and discriminating these from each other is challenging at the molecular level owing to underlying stochastic behaviour. Analysis is traditionally performed using mean square displacements of tracked particles; however, this generally requires more data points than is typical for single FP tracks owing to photophysical instability. Presented here is a novel approach allowing robust Bayesian ranking of diffusion processes to discriminate multiple complex modes probabilistically. It is a computational approach that biologists can use to understand single-molecule features in live cells. PMID:23267182

Advances in the microrheology of complex fluids

NASA Astrophysics Data System (ADS)

Waigh, Thomas Andrew

2016-07-01

New developments in the microrheology of complex fluids are considered. Firstly the requirements for a simple modern particle tracking microrheology experiment are introduced, the error analysis methods associated with it and the mathematical techniques required to calculate the linear viscoelasticity. Progress in microrheology instrumentation is then described with respect to detectors, light sources, colloidal probes, magnetic tweezers, optical tweezers, diffusing wave spectroscopy, optical coherence tomography, fluorescence correlation spectroscopy, elastic- and quasi-elastic scattering techniques, 3D tracking, single molecule methods, modern microscopy methods and microfluidics. New theoretical techniques are also reviewed such as Bayesian analysis, oversampling, inversion techniques, alternative statistical tools for tracks (angular correlations, first passage probabilities, the kurtosis, motor protein step segmentation etc), issues in micro/macro rheological agreement and two particle methodologies. Applications where microrheology has begun to make some impact are also considered including semi-flexible polymers, gels, microorganism biofilms, intracellular methods, high frequency viscoelasticity, comb polymers, active motile fluids, blood clots, colloids, granular materials, polymers, liquid crystals and foods. Two large emergent areas of microrheology, non-linear microrheology and surface microrheology are also discussed.

DNA fragmentation by charged particle tracks.

PubMed

Stenerlow, B; Hoglund, E; Carlsson, J

2002-01-01

High-LET (linear energy transfer) charged particles induce DNA double-strand breaks (DSB) in a non-random fashion in mammalian cells. The clustering of DSB, probably determined by track structure as well as chromatin conformation, results in an excess of small- and intermediate-sized DNA fragments. DNA fragmentation in normal human fibroblasts (GM5758) was analyzed by pulsed-field gel electrophoresis after irradiation with photons (60Co) or 125 keV/micrometers nitrogen ions. Compared to conventional DSB analysis, i.e. assays only measuring the fraction of DNA smaller than a single threshold, the relative biological effectiveness (RBE) for DSB induction increased with 100%. Further, the size distribution of DNA fragments showed a significant dependence on radiation quality, with an excess of fragments up to 1 Mbp. Irradiation of naked genomic DNA without histone proteins increased the DSB yields 25 and 13 times for photons and nitrogen ions, respectively. The results suggest possible roles of both track structure and chromatin organization in the distribution of DNA double-strand breaks along the chromosome. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Chromosomal locus tracking with proper accounting of static and dynamic errors

PubMed Central

Backlund, Mikael P.; Joyner, Ryan; Moerner, W. E.

2015-01-01

The mean-squared displacement (MSD) and velocity autocorrelation (VAC) of tracked single particles or molecules are ubiquitous metrics for extracting parameters that describe the object’s motion, but they are both corrupted by experimental errors that hinder the quantitative extraction of underlying parameters. For the simple case of pure Brownian motion, the effects of localization error due to photon statistics (“static error”) and motion blur due to finite exposure time (“dynamic error”) on the MSD and VAC are already routinely treated. However, particles moving through complex environments such as cells, nuclei, or polymers often exhibit anomalous diffusion, for which the effects of these errors are less often sufficiently treated. We present data from tracked chromosomal loci in yeast that demonstrate the necessity of properly accounting for both static and dynamic error in the context of an anomalous diffusion that is consistent with a fractional Brownian motion (FBM). We compare these data to analytical forms of the expected values of the MSD and VAC for a general FBM in the presence of these errors. PMID:26172745

Lipid membrane-assisted condensation and assembly of amphiphilic Janus particles

DOE PAGES

Chambers, Mariah; Mallory, Stewart Anthony; Malone, Heather; ...

2016-01-01

Amphiphilic Janus particles self-assemble into complex metastructures, but little is known about how their assembly might be modified by weak interactions with a nearby biological membrane surface. Here, we report an integrated experimental and molecular dynamics simulation study to investigate the self-assembly of amphiphilic Janus particles on a lipid membrane. We created an experimental system in which Janus particles are allowed to self-assemble in the same medium where zwitterionic lipids form giant unilamellar vesicles (GUVs). Janus particles spontaneously concentrated on the inner leaflet of the GUVs. They exhibited biased orientation and heterogeneous rotational dynamics as revealed by single particle rotationalmore » tracking. The combined experimental and simulation results show that Janus particles concentrate on the lipid membranes due to weak particle–lipid attraction, whereas the biased orientation of particles is driven predominantly by inter-particle interactions. Furthermore, this study demonstrates the potential of using lipid membranes to influence the self-assembly of Janus particles.« less

Optoelectronic tweezers integrated with lensfree holographic microscopy for wide-field interactive cell and particle manipulation on a chip.

PubMed

Huang, Kuo-Wei; Su, Ting-Wei; Ozcan, Aydogan; Chiou, Pei-Yu

2013-06-21

We demonstrate an optoelectronic tweezer (OET) coupled to a lensfree holographic microscope for real-time interactive manipulation of cells and micro-particles over a large field-of-view (FOV). This integrated platform can record the holographic images of cells and particles over the entire active area of a CCD sensor array, perform digital image reconstruction to identify target cells, dynamically track the positions of cells and particles, and project light beams to trigger light-induced dielectrophoretic forces to pattern and sort cells on a chip. OET technology has been previously shown to be capable of performing parallel single cell manipulation over a large area. However, its throughput has been bottlenecked by the number of cells that can be imaged within the limited FOV of a conventional microscope objective lens. Integrating lensfree holographic imaging with OET solves this fundamental FOV barrier, while also creating a compact on-chip cell/particle manipulation platform. Using this unique platform, we have successfully demonstrated real-time interactive manipulation of thousands of single cells and micro-particles over an ultra-large area of e.g., 240 mm(2) (i.e. 17.96 mm × 13.52 mm).

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

Myhra, S., E-mail: sverre.myhra@materials.ox.ac.uk; Chakalova, R.; Falzone, N.

A method for detection and characterization of single MeV α-particle and recoil tracks in PMMA photoresist by atomic force microscopy (AFM) analysis has been demonstrated. The energy deposition along the track is shown to lead to a latent pattern in the resist due to contrast reversal. It has been shown that the pattern, consisting of conical spikes, can be developed by conventional processing as a result of the dissolution rate of poly(methyl methacrylate) (PMMA) being greater than that for the modified material in the cylindrical volume of the track core. The spikes can be imaged and counted by routine AFMmore » analysis. Investigations by angular-resolved near-grazing incidence reveal additional tracks that correspond to recoil tracks. The observations have been correlated with modelling, and shown to be in qualitative agreement with prevailing descriptions of collision cascades. The results may be relevant to technologies that are based on detection and characterization of single energetic ions. In particular, the direct visualization of the collision cascade may allow more accurate estimates of the actual interaction volume, which in turn will permit more precise assessment of dose distribution of α-emitting radionuclides used for targeted radiotherapy. The results could also be relevant to other diagnostic or process technologies based on interaction of energetic ions with matter.« less

Tracking and people counting using Particle Filter Method

NASA Astrophysics Data System (ADS)

Sulistyaningrum, D. R.; Setiyono, B.; Rizky, M. S.

2018-03-01

In recent years, technology has developed quite rapidly, especially in the field of object tracking. Moreover, if the object under study is a person and the number of people a lot. The purpose of this research is to apply Particle Filter method for tracking and counting people in certain area. Tracking people will be rather difficult if there are some obstacles, one of which is occlusion. The stages of tracking and people counting scheme in this study include pre-processing, segmentation using Gaussian Mixture Model (GMM), tracking using particle filter, and counting based on centroid. The Particle Filter method uses the estimated motion included in the model used. The test results show that the tracking and people counting can be done well with an average accuracy of 89.33% and 77.33% respectively from six videos test data. In the process of tracking people, the results are good if there is partial occlusion and no occlusion

Coupling channel evolution monitoring and RFID tracking in a large, wandering, gravel-bed river: Insights into sediment routing on geomorphic continuity through a riffle-pool sequence

NASA Astrophysics Data System (ADS)

Chapuis, Margot; Dufour, Simon; Provansal, Mireille; Couvert, Bernard; de Linares, Matthieu

2015-02-01

Bedload transport and bedform mobility in large gravel-bed rivers are not easily monitored, especially during floods. Large reaches present difficulties in bed access during flows for flow measurements. Because of these logistical issues, the current knowledge about bedload transport processes and bedform mobility lacks field-based information, while this missing information would precisely match river management needs. The lack of information linking channel evolution and particle displacements is even more striking in wandering reaches. The Durance River is a large, wandering, gravel-bed river (catchment area: 14,280 km2; mean width: 240 m), located in the southern French Alps and highly impacted by flow diversion and gravel mining. In order to improve current understanding of the link between sediment transport processes and river bed morphodynamics, we set up a sediment particle survey in the channel using Radio Frequency Identification (RFID) tracking and topographic surveys (GPS RTK and scour chains) for a 4-year recurrence interval flood. By combining topographic changes before and after a flood, intraflood erosion/deposition patterns from scour chains, differential routing of tracer particles, and spatial distribution of bed shear stress through a complex reach, this paper aims to define the critical shear stress for significant sediment mobility in this setting. Gravel tracking highlights displacement patterns in agreement with bar downstream migration and transport of particles across the riffle within this single flood event. Because no velocity measurements were possible during flood, a TELEMAC three-dimensional model helped interpret particle displacements by estimating spatial distribution of shear stresses and flow directions at peak flow. Although RFID tracking in a large, wandering, gravel-bed river does have some technical limitations (burial, recovery process time-consuming), it provides useful information on sediment routing through a riffle-pool sequence.

Single molecule analysis of B cell receptor motion during signaling activation

NASA Astrophysics Data System (ADS)

Rey Suarez, Ivan; Koo, Peter; Zhou, Shu; Wheatley, Brittany; Song, Wenxia; Mochrie, Simon; Upadhyaya, Arpita

B cells are an essential part of the adaptive immune system. They patrol the body for signs of infection in the form of antigen on the surface of antigen presenting cells. B cell receptor (BCR) binding to antigen induces a signaling cascade that leads to B cell activation and spreading. During activation, BCR form signaling microclusters that later coalesce as the cell contracts. We have studied the dynamics of BCRs on activated murine primary B cells using single particle tracking. The tracks are analyzed using perturbation expectation-maximization (pEM), a systems-level analysis, which allows identification of different short-time diffusive states from single molecule tracks. We identified four dominant diffusive states, two of which correspond to BCRs interacting with signaling molecules. For wild-type cells, the number of BCR in signaling states increases as the cell spreads and then decreases during cell contraction. In contrast, cells lacking the actin regulatory protein, N-WASP, are unable to contract and BCRs remain in the signaling states for longer times. These observations indicate that actin cytoskeleton dynamics modulate BCR diffusion and clustering. Our results provide novel information regarding the timescale of interaction between BCR and signaling molecules.

Adaptive particle filter for robust visual tracking

NASA Astrophysics Data System (ADS)

Dai, Jianghua; Yu, Shengsheng; Sun, Weiping; Chen, Xiaoping; Xiang, Jinhai

2009-10-01

Object tracking plays a key role in the field of computer vision. Particle filter has been widely used for visual tracking under nonlinear and/or non-Gaussian circumstances. In particle filter, the state transition model for predicting the next location of tracked object assumes the object motion is invariable, which cannot well approximate the varying dynamics of the motion changes. In addition, the state estimate calculated by the mean of all the weighted particles is coarse or inaccurate due to various noise disturbances. Both these two factors may degrade tracking performance greatly. In this work, an adaptive particle filter (APF) with a velocity-updating based transition model (VTM) and an adaptive state estimate approach (ASEA) is proposed to improve object tracking. In APF, the motion velocity embedded into the state transition model is updated continuously by a recursive equation, and the state estimate is obtained adaptively according to the state posterior distribution. The experiment results show that the APF can increase the tracking accuracy and efficiency in complex environments.

Revealing region-specific biofilm viscoelastic properties by means of a micro-rheological approach.

PubMed

Cao, Huayu; Habimana, Olivier; Safari, Ashkan; Heffernan, Rory; Dai, Yihong; Casey, Eoin

2016-01-01

Particle-tracking microrheology is an in situ technique that allows quantification of biofilm material properties. It overcomes the limitations of alternative techniques such as bulk rheology or force spectroscopy by providing data on region specific material properties at any required biofilm location and can be combined with confocal microscopy and associated structural analysis. This article describes single particle tracking microrheology combined with confocal laser scanning microscopy to resolve the biofilm structure in 3 dimensions and calculate the creep compliances locally. Samples were analysed from Pseudomonas fluorescens biofilms that were cultivated over two timescales (24 h and 48 h) and alternate ionic conditions (with and without calcium chloride supplementation). The region-based creep compliance analysis showed that the creep compliance of biofilm void zones is the primary contributor to biofilm mechanical properties, contributing to the overall viscoelastic character.

Bayesian approach to MSD-based analysis of particle motion in live cells.

PubMed

Monnier, Nilah; Guo, Syuan-Ming; Mori, Masashi; He, Jun; Lénárt, Péter; Bathe, Mark

2012-08-08

Quantitative tracking of particle motion using live-cell imaging is a powerful approach to understanding the mechanism of transport of biological molecules, organelles, and cells. However, inferring complex stochastic motion models from single-particle trajectories in an objective manner is nontrivial due to noise from sampling limitations and biological heterogeneity. Here, we present a systematic Bayesian approach to multiple-hypothesis testing of a general set of competing motion models based on particle mean-square displacements that automatically classifies particle motion, properly accounting for sampling limitations and correlated noise while appropriately penalizing model complexity according to Occam's Razor to avoid over-fitting. We test the procedure rigorously using simulated trajectories for which the underlying physical process is known, demonstrating that it chooses the simplest physical model that explains the observed data. Further, we show that computed model probabilities provide a reliability test for the downstream biological interpretation of associated parameter values. We subsequently illustrate the broad utility of the approach by applying it to disparate biological systems including experimental particle trajectories from chromosomes, kinetochores, and membrane receptors undergoing a variety of complex motions. This automated and objective Bayesian framework easily scales to large numbers of particle trajectories, making it ideal for classifying the complex motion of large numbers of single molecules and cells from high-throughput screens, as well as single-cell-, tissue-, and organism-level studies. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Revealing nonergodic dynamics in living cells from a single particle trajectory

NASA Astrophysics Data System (ADS)

Lanoiselée, Yann; Grebenkov, Denis S.

2016-05-01

We propose the improved ergodicity and mixing estimators to identify nonergodic dynamics from a single particle trajectory. The estimators are based on the time-averaged characteristic function of the increments and can thus capture additional information on the process as compared to the conventional time-averaged mean-square displacement. The estimators are first investigated and validated for several models of anomalous diffusion, such as ergodic fractional Brownian motion and diffusion on percolating clusters, and nonergodic continuous-time random walks and scaled Brownian motion. The estimators are then applied to two sets of earlier published trajectories of mRNA molecules inside live Escherichia coli cells and of Kv2.1 potassium channels in the plasma membrane. These statistical tests did not reveal nonergodic features in the former set, while some trajectories of the latter set could be classified as nonergodic. Time averages along such trajectories are thus not representative and may be strongly misleading. Since the estimators do not rely on ensemble averages, the nonergodic features can be revealed separately for each trajectory, providing a more flexible and reliable analysis of single-particle tracking experiments in microbiology.

Membrane Fluidity Sensing on the Single Virus Particle Level with Plasmonic Nanoparticle Transducers.

PubMed

Feizpour, Amin; Stelter, David; Wong, Crystal; Akiyama, Hisashi; Gummuluru, Suryaram; Keyes, Tom; Reinhard, Björn M

2017-10-27

Viral membranes are nanomaterials whose fluidity depends on their composition, in particular, the cholesterol (chol) content. As differences in the membrane composition of individual virus particles can lead to different intracellular fates, biophysical tools capable of sensing the membrane fluidity on the single-virus level are required. In this manuscript, we demonstrate that fluctuations in the polarization of light scattered off gold or silver nanoparticle (NP)-labeled virus-like-particles (VLPs) encode information about the membrane fluidity of individual VLPs. We developed plasmonic polarization fluctuation tracking microscopy (PFTM) which facilitated the investigation of the effect of chol content on the membrane fluidity and its dependence on temperature, for the first time on the single-VLP level. Chol extraction studies with different methyl-β-cyclodextrin (MβCD) concentrations yielded a gradual decrease in polarization fluctuations as a function of time. The rate of chol extraction for individual VLPs showed a broad spread, presumably due to differences in the membrane composition for the individual VLPs, and this heterogeneity increased with decreasing MβCD concentration.

Micro-heterogeneity of corn hulls cellulosic fiber biopolymer studied by multiple-particle tracking (MPT)

USDA-ARS?s Scientific Manuscript database

A novel technique named multiple-particle tracking (MPT) was used to investigate the micro-structural heterogeneities of Z-trim, a zero calorie cellulosic fiber biopolymer produced from corn hulls. The Multiple-Particle Tracking (MPT) method was used in this study, which was originally described by ...

A high-speed tracking algorithm for dense granular media

NASA Astrophysics Data System (ADS)

Cerda, Mauricio; Navarro, Cristóbal A.; Silva, Juan; Waitukaitis, Scott R.; Mujica, Nicolás; Hitschfeld, Nancy

2018-06-01

Many fields of study, including medical imaging, granular physics, colloidal physics, and active matter, require the precise identification and tracking of particle-like objects in images. While many algorithms exist to track particles in diffuse conditions, these often perform poorly when particles are densely packed together-as in, for example, solid-like systems of granular materials. Incorrect particle identification can have significant effects on the calculation of physical quantities, which makes the development of more precise and faster tracking algorithms a worthwhile endeavor. In this work, we present a new tracking algorithm to identify particles in dense systems that is both highly accurate and fast. We demonstrate the efficacy of our approach by analyzing images of dense, solid-state granular media, where we achieve an identification error of 5% in the worst evaluated cases. Going further, we propose a parallelization strategy for our algorithm using a GPU, which results in a speedup of up to 10 × when compared to a sequential CPU implementation in C and up to 40 × when compared to the reference MATLAB library widely used for particle tracking. Our results extend the capabilities of state-of-the-art particle tracking methods by allowing fast, high-fidelity detection in dense media at high resolutions.

Fast human pose estimation using 3D Zernike descriptors

NASA Astrophysics Data System (ADS)

Berjón, Daniel; Morán, Francisco

2012-03-01

Markerless video-based human pose estimation algorithms face a high-dimensional problem that is frequently broken down into several lower-dimensional ones by estimating the pose of each limb separately. However, in order to do so they need to reliably locate the torso, for which they typically rely on time coherence and tracking algorithms. Their losing track usually results in catastrophic failure of the process, requiring human intervention and thus precluding their usage in real-time applications. We propose a very fast rough pose estimation scheme based on global shape descriptors built on 3D Zernike moments. Using an articulated model that we configure in many poses, a large database of descriptor/pose pairs can be computed off-line. Thus, the only steps that must be done on-line are the extraction of the descriptors for each input volume and a search against the database to get the most likely poses. While the result of such process is not a fine pose estimation, it can be useful to help more sophisticated algorithms to regain track or make more educated guesses when creating new particles in particle-filter-based tracking schemes. We have achieved a performance of about ten fps on a single computer using a database of about one million entries.

Microstructure and properties of TiB2-TiB reinforced titanium matrix composite coating by laser cladding

NASA Astrophysics Data System (ADS)

Lin, Yinghua; Yao, Jianhua; Lei, Yongping; Fu, Hanguang; Wang, Liang

2016-11-01

TiB2 particle and TiB short fiber reinforced titanium matrix composite coatings were prepared utilizing in situ synthesized technique by laser cladding on the surface of Ti6Al4V alloy. Through the experiment, it was found that the surface of the single-track coatings appeared in the depression, but it can be improved by laser track overlapping. With the increase of laser power density, the amount of TiB short fiber was increased, and the distribution of TiB2 and TiB became more uniform from the top to bottom. The micro-hardness of TiB2/TiB coating showed a gradient decreasing trend, and the average micro-hardness of the coatings was two-fold higher than that of the substrate. Due to the strengthening effect of TiB2 particle and TiB short fiber, the wear volume loss of the center of the coating was approximately 30% less than that of the Ti-6Al-4V substrate, and the wear mechanism of the coating was mild fatigue particle detachment.

Tracks to therapy

NASA Technical Reports Server (NTRS)

Katz, R.; Cucinotta, F. A.

1999-01-01

Studies of the structure of particle tracks have led to models of track effects based on radial dose and radiobiological target theory that have been very successful in describing and predicting track effects in physical, chemical, and biological systems. For describing mammalian cellular inactivation two inactivation modes are required, called gamma-kill and ion-kill, the first due to synergistic effects of delta rays from adjacent ion paths thus resembling the effects from gamma rays, and the second to the effects of single ion transits through a cell nucleus. The ion-kill effect is more severe, where the fraction of cells experiencing ion kill is responsible for a decrease in the oxygen enhancement ratio, and an increase in relative biological effectiveness, but these are accompanied by loss of repair, hence to a reduction in the efficiency of fractionation in high LET therapy, as shown by our calculations for radiobiological effects in the "spread out Bragg Peak".

Modes of Diffusion of Cholera Toxin Bound to GM1 on Live Cell Membrane by Image Mean Square Displacement Analysis

PubMed Central

Moens, Pierre D.J.; Digman, Michelle A.; Gratton, Enrico

2015-01-01

The image-mean square displacement technique applies the calculation of the mean square displacement commonly used in single-molecule tracking to images without resolving single particles. The image-mean square displacement plot obtained is similar to the mean square displacement plot obtained using the single-particle tracking technique. This plot is then used to reconstruct the protein diffusion law and to identify whether the labeled molecules are undergoing pure isotropic, restricted, corralled, transiently confined, or directed diffusion. In our study total internal reflection fluorescence microscopy images were taken of Cholera toxin subunit B (CtxB) membrane-labeled NIH 3T3 mouse fibroblasts and MDA 231 MB cells. We found a population of CTxB undergoing purely isotropic diffusion and one displaying restricted diffusion with corral sizes ranging from 150 to ∼1800 nm. We show that the diffusion rate of CTxB bound to GM1 is independent of the size of the confinement, suggesting that the mechanism of confinement is different from the mechanism controlling the diffusion rate of CtxB. We highlight the potential effect of continuous illumination on the diffusion mode of CTxB. We also show that aggregation of CTxB/GM1 in large complexes occurs and that these aggregates tend to have slower diffusion rates. PMID:25809257

Modes of diffusion of cholera toxin bound to GM1 on live cell membrane by image mean square displacement analysis.

PubMed

Moens, Pierre D J; Digman, Michelle A; Gratton, Enrico

2015-03-24

The image-mean square displacement technique applies the calculation of the mean square displacement commonly used in single-molecule tracking to images without resolving single particles. The image-mean square displacement plot obtained is similar to the mean square displacement plot obtained using the single-particle tracking technique. This plot is then used to reconstruct the protein diffusion law and to identify whether the labeled molecules are undergoing pure isotropic, restricted, corralled, transiently confined, or directed diffusion. In our study total internal reflection fluorescence microscopy images were taken of Cholera toxin subunit B (CtxB) membrane-labeled NIH 3T3 mouse fibroblasts and MDA 231 MB cells. We found a population of CTxB undergoing purely isotropic diffusion and one displaying restricted diffusion with corral sizes ranging from 150 to ∼1800 nm. We show that the diffusion rate of CTxB bound to GM1 is independent of the size of the confinement, suggesting that the mechanism of confinement is different from the mechanism controlling the diffusion rate of CtxB. We highlight the potential effect of continuous illumination on the diffusion mode of CTxB. We also show that aggregation of CTxB/GM1 in large complexes occurs and that these aggregates tend to have slower diffusion rates. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Higher-order architecture of rhodopsin in intact photoreceptors and its implication for phototransduction kinetics.

PubMed

Gunkel, Monika; Schöneberg, Johannes; Alkhaldi, Weaam; Irsen, Stephan; Noé, Frank; Kaupp, U Benjamin; Al-Amoudi, Ashraf

2015-04-07

The visual pigment rhodopsin belongs to the family of G protein-coupled receptors that can form higher oligomers. It is controversial whether rhodopsin forms oligomers and whether oligomers are functionally relevant. Here, we study rhodopsin organization in cryosections of dark-adapted mouse rod photoreceptors by cryoelectron tomography. We identify four hierarchical levels of organization. Rhodopsin forms dimers; at least ten dimers form a row. Rows form pairs (tracks) that are aligned parallel to the disk incisures. Particle-based simulation shows that the combination of tracks with fast precomplex formation, i.e. rapid association and dissociation between inactive rhodopsin and the G protein transducin, leads to kinetic trapping: rhodopsin first activates transducin from its own track, whereas recruitment of transducin from other tracks proceeds more slowly. The trap mechanism could produce uniform single-photon responses independent of rhodopsin lifetime. In general, tracks might provide a platform that coordinates the spatiotemporal interaction of signaling molecules. Copyright © 2015 Elsevier Ltd. All rights reserved.

Application of geocomposite placed beneath ballast bed to improve ballast quality and track stability

NASA Astrophysics Data System (ADS)

Horníček, Leoš; Břešt'ovský, Petr; Jasanský, Petr

2017-09-01

The article deals with the application of a stabilization hexagonal geocomposite for the improvement of poor stability of railway tracks caused by undesirable migration of fine soil particles from the subgrade into the ballast bed. The establishment of a test railway section on a single-line track situated near Domazlice and its long-term monitoring programme are described. Evaluation is aimed especially at track geometry parameters, the load-bearing capacity of the ballast bed, elastic rail deflection during train passages and the durability of geocomposite’s physical properties. The data taken from the test section during five measurement campaigns are compared with both adjacent sections. In one of them, only the ballast bed renovation was carried out, whereas in the second one no intervention was performed at all. The usage of a pioneering geosynthetic product in combination with new trends in ballast bed restoration seems to be an innovative as well as effective solution to analogous problematic spots on railway tracks in the Czech Republic.

Magnetic particle tracking for nonspherical particles in a cylindrical fluidized bed.

PubMed

Buist, Kay A; Jayaprakash, Pavithra; Kuipers, J A M; Deen, Niels G; Padding, Johan T

2017-12-01

In granular flow operations, often particles are nonspherical. This has inspired a vast amount of research in understanding the behavior of these particles. Various models are being developed to study the hydrodynamics involving nonspherical particles. Experiments however are often limited to obtain data on the translational motion only. This paper focusses on the unique capability of Magnetic Particle Tracking to track the orientation of a marker in a full 3-D cylindrical fluidized bed. Stainless steel particles with the same volume and different aspect ratios are fluidized at a range of superficial gas velocities. Spherical and rod-like particles show distinctly different fluidization behavior. Also, the distribution of angles for rod-like particles changes with position in the fluidized bed as well as with the superficial velocity. Magnetic Particle Tracking shows its unique capability to study both spatial distribution and orientation of the particles allowing more in-depth validation of Discrete Particle Models. © 2017 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers , 63: 5335-5342, 2017.

Relationship between axenic growth of Dictyostelium discoideum strains and their track morphology on substrates coated with gold particles

PubMed Central

1983-01-01

Amoebae of Dictyostelium discoideum produce tracks with two distinct morphologies on gold-coated coverslips. The wild-type strain and other strains that feed only by phagocytosis produced indistinct, fuzzy tracks, whereas mutants capable of axenic growth produced clear, sharp tracks. The sharp track morphology was found to be a recessive phenotype that segregates with axenicity and probably requires a previously unidentified axenic mutation. Axenic and nonaxenic strains also differed in their ability to pinocytose. When the two types of cells were shifted from bacterial growth plates to nutrient media, within 24 h the axenic strain established a rapid rate of pinocytosis, approximately 100-fold higher than the low rate detectable for the nonaxenic strain. However, track formation did not appear to be directly related to endocytosis. Electron microscopic examination of cells during track formation showed that both axenic and nonaxenic strains accumulated gold particles on their surfaces, but neither strain internalized the gold to any significant degree. Observation of living cells revealed that axenic strains collected all particles that they contacted, whereas wild-type strains left many particles undisturbed. The size of the gold particle clusters discarded by the cells also contributed to track morphology. PMID:6619183

Neutral Mass Spectrometry of Mega-Dalton Particles with Single-Particle Resolution using a Nano-Electromechanical System

NASA Astrophysics Data System (ADS)

Kelber, Scott; Hanay, Mehmet; Naik, Akshay; Chi, Derrick; Hentz, Sebastien; Bullard, Caryn; Collinet, Eric; Duraffourg, Laurent; Roukes, Michael

2012-02-01

Nanoelectromechanical systems (NEMS) enable mass sensing with unprecedented sensitivity and mass dynamic range. Previous works have relied on statistical analysis of multiple landing events to assemble mass spectra. Here we demonstrate the utility of using multiple modes of the NEMS device in determining the mass of individual molecules landing on the NEMS. Analyte particles in vapor form are produced using matrix assisted laser desorption ionization. Resonant frequencies of the first two modes of a single NEMS device, placed in close proximity to the analyte source, are tracked using parallel phase locked loops. Each analyte molecule landing on the NEMS generates a distinct frequency shift in the two modes. These time correlated frequency jumps are used to evaluate the mass of each analyte particle landing on the NEMS and thus generate mass spectra. We present the latest experimental results using this scheme and also demonstrate the utility for mass spectrometry of large biomolecules. This NEMS-Mass Spec. system offers a new tool for structural biology and pathology for the analysis of large proteins, protein complexes, and viruses.

Interferometric scattering (iSCAT) microscopy: studies of biological membrane dynamics

NASA Astrophysics Data System (ADS)

Reina, Francesco; Galiani, Silvia; Shrestha, Dilip; Sezgin, Erdinc; Lagerholm, B. Christoffer; Cole, Daniel; Kukura, Philipp; Eggeling, Christian

2018-02-01

The study of the organization and dynamics of molecules in model and cellular membranes is an important topic in contemporary biophysics. Imaging and single particle tracking in this particular field, however, proves particularly demanding, as it requires simultaneously high spatio-temporal resolution and high signal-to-noise ratios. A remedy to this challenge might be Interferometric Scattering (iSCAT) microscopy, due to its fast sampling rates, label-free imaging capabilities and, most importantly, tuneable signal level output. Here we report our recent advances in the imaging and molecular tracking on phase-separated model membrane systems and live-cell membranes using this technique.

Direct measurement of the 3-dimensional DNA lesion distribution induced by energetic charged particles in a mouse model tissue

PubMed Central

Mirsch, Johanna; Tommasino, Francesco; Frohns, Antonia; Conrad, Sandro; Durante, Marco; Scholz, Michael; Friedrich, Thomas; Löbrich, Markus

2015-01-01

Charged particles are increasingly used in cancer radiotherapy and contribute significantly to the natural radiation risk. The difference in the biological effects of high-energy charged particles compared with X-rays or γ-rays is determined largely by the spatial distribution of their energy deposition events. Part of the energy is deposited in a densely ionizing manner in the inner part of the track, with the remainder spread out more sparsely over the outer track region. Our knowledge about the dose distribution is derived solely from modeling approaches and physical measurements in inorganic material. Here we exploited the exceptional sensitivity of γH2AX foci technology and quantified the spatial distribution of DNA lesions induced by charged particles in a mouse model tissue. We observed that charged particles damage tissue nonhomogenously, with single cells receiving high doses and many other cells exposed to isolated damage resulting from high-energy secondary electrons. Using calibration experiments, we transformed the 3D lesion distribution into a dose distribution and compared it with predictions from modeling approaches. We obtained a radial dose distribution with sub-micrometer resolution that decreased with increasing distance to the particle path following a 1/r2 dependency. The analysis further revealed the existence of a background dose at larger distances from the particle path arising from overlapping dose deposition events from independent particles. Our study provides, to our knowledge, the first quantification of the spatial dose distribution of charged particles in biologically relevant material, and will serve as a benchmark for biophysical models that predict the biological effects of these particles. PMID:26392532

Robust visual tracking via multiscale deep sparse networks

NASA Astrophysics Data System (ADS)

Wang, Xin; Hou, Zhiqiang; Yu, Wangsheng; Xue, Yang; Jin, Zefenfen; Dai, Bo

2017-04-01

In visual tracking, deep learning with offline pretraining can extract more intrinsic and robust features. It has significant success solving the tracking drift in a complicated environment. However, offline pretraining requires numerous auxiliary training datasets and is considerably time-consuming for tracking tasks. To solve these problems, a multiscale sparse networks-based tracker (MSNT) under the particle filter framework is proposed. Based on the stacked sparse autoencoders and rectifier linear unit, the tracker has a flexible and adjustable architecture without the offline pretraining process and exploits the robust and powerful features effectively only through online training of limited labeled data. Meanwhile, the tracker builds four deep sparse networks of different scales, according to the target's profile type. During tracking, the tracker selects the matched tracking network adaptively in accordance with the initial target's profile type. It preserves the inherent structural information more efficiently than the single-scale networks. Additionally, a corresponding update strategy is proposed to improve the robustness of the tracker. Extensive experimental results on a large scale benchmark dataset show that the proposed method performs favorably against state-of-the-art methods in challenging environments.

Resistive-strips micromegas detectors with two-dimensional readout

NASA Astrophysics Data System (ADS)

Byszewski, M.; Wotschack, J.

2012-02-01

Micromegas detectors show very good performance for charged particle tracking in high rate environments as for example at the LHC. It is shown that two coordinates can be extracted from a single gas gap in these detectors. Several micromegas chambers with spark protection by resistive strips and two-dimensional readout have been tested in the context of the R&D work for the ATLAS Muon System upgrade.

Cosmic ray particle dosimetry and trajectory tracing. [cosmic ray track analysis for Apollo 17 BIOCORE

NASA Technical Reports Server (NTRS)

Cruty, M. R.; Benton, E. V.; Turnbill, C. E.; Philpott, D. E.

1975-01-01

Five pocket mice (Perognathus longimembris) were flown on Apollo XVII, each with a solid-state (plastic) nuclear track detector implanted beneath its scalp. The subscalp detectors were sensitive to HZE cosmic ray particles with a LET greater than or approximately equal to 0.15 million electron volts per micrometer (MeV/micron). A critical aspect of the dosimetry of the experiment involved tracing individual particle trajectories through each mouse head from particle tracks registered in the individual subscalp detectors, thereby establishing a one-to-one correspondence between a trajectory location in the tissue and the presence or absence of a lesion. The other major aspect was the identification of each registered particle. An average of 16 particles with Z greater than or equal to 6 and 2.2 particles with Z greater than or equal to 20 were found per detector. The track density, 29 tracks/sq cm, when adjusted for detection volume, was in agreement with the photographic emulsion data from an area dosimeter located next to the flight package.

Chemistry and particle track studies of Apollo 14 glasses.

NASA Technical Reports Server (NTRS)

Glass, B. P.; Storzer, D.; Wagner, G. A.

1972-01-01

The abundance and the composition of Apollo 14 glasses have been studied. Glass particles were analyzed for Si, Ti, Al, Fe, Mn, Mg, Na, and K by electron microprobe analysis. The refractive indices of 26 particles were determined by the oil immersion method. Track analyses have been carried out in order to determine the uranium content and the radiation history of glass particles. The proper identification of galactic and solar flare nuclei tracks makes it possible to estimated residence times of the glass particles in the top layer of the lunar soil.

Semianalytical computation of path lines for finite-difference models

USGS Publications Warehouse

Pollock, D.W.

1988-01-01

A semianalytical particle tracking method was developed for use with velocities generated from block-centered finite-difference ground-water flow models. Based on the assumption that each directional velocity component varies linearly within a grid cell in its own coordinate directions, the method allows an analytical expression to be obtained describing the flow path within an individual grid cell. Given the intitial position of a particle anywhere in a cell, the coordinates of any other point along its path line within the cell, and the time of travel between them, can be computed directly. For steady-state systems, the exit point for a particle entering a cell at any arbitrary location can be computed in a single step. By following the particle as it moves from cell to cell, this method can be used to trace the path of a particle through any multidimensional flow field generated from a block-centered finite-difference flow model. -Author

Modeling the solute transport by particle-tracing method with variable weights

NASA Astrophysics Data System (ADS)

Jiang, J.

2016-12-01

Particle-tracing method is usually used to simulate the solute transport in fracture media. In this method, the concentration at one point is proportional to number of particles visiting this point. However, this method is rather inefficient at the points with small concentration. Few particles visit these points, which leads to violent oscillation or gives zero value of concentration. In this paper, we proposed a particle-tracing method with variable weights. The concentration at one point is proportional to the sum of the weights of the particles visiting it. It adjusts the weight factors during simulations according to the estimated probabilities of corresponding walks. If the weight W of a tracking particle is larger than the relative concentration C at the corresponding site, the tracking particle will be splitted into Int(W/C) copies and each copy will be simulated independently with the weight W/Int(W/C) . If the weight W of a tracking particle is less than the relative concentration C at the corresponding site, the tracking particle will be continually tracked with a probability W/C and the weight will be adjusted to be C. By adjusting weights, the number of visiting particles distributes evenly in the whole range. Through this variable weights scheme, we can eliminate the violent oscillation and increase the accuracy of orders of magnitudes.

MEASURING PROJECTOR

DOEpatents

Franck, J.V.; Broadhead, P.S.; Skiff, E.W.

1959-07-14

A semiautomatic measuring projector particularly adapted for measurement of the coordinates of photographic images of particle tracks as prcduced in a bubble or cloud chamber is presented. A viewing screen aids the operator in selecting a particle track for measurement. After approximate manual alignment, an image scanning system coupled to a servo control provides automatic exact alignment of a track image with a reference point. The apparatus can follow along a track with a continuous motion while recording coordinate data at various selected points along the track. The coordinate data is recorded on punched cards for subsequent computer calculation of particle trajectory, momentum, etc.

Particle Deposition in Human Lungs due to Varying Cross-Sectional Ellipticity of Left and Right Main Bronchi

NASA Astrophysics Data System (ADS)

Roth, Steven; Oakes, Jessica; Shadden, Shawn

2015-11-01

Particle deposition in the human lungs can occur with every breathe. Airbourne particles can range from toxic constituents (e.g. tobacco smoke and air pollution) to aerosolized particles designed for drug treatment (e.g. insulin to treat diabetes). The effect of various realistic airway geometries on complex flow structures, and thus particle deposition sites, has yet to be extensively investigated using computational fluid dynamics (CFD). In this work, we created an image-based geometric airway model of the human lung and performed CFD simulations by employing multi-domain methods. Following the flow simulations, Lagrangian particle tracking was used to study the effect of cross-sectional shape on deposition sites in the conducting airways. From a single human lung model, the cross-sectional ellipticity (the ratio of major and minor diameters) of the left and right main bronchi was varied systematically from 2:1 to 1:1. The influence of the airway ellipticity on the surrounding flow field and particle deposition was determined.

Time-resolved large-scale volumetric pressure fields of an impinging jet from dense Lagrangian particle tracking

NASA Astrophysics Data System (ADS)

Huhn, F.; Schanz, D.; Manovski, P.; Gesemann, S.; Schröder, A.

2018-05-01

Time-resolved volumetric pressure fields are reconstructed from Lagrangian particle tracking with high seeding concentration using the Shake-The-Box algorithm in a perpendicular impinging jet flow with exit velocity U=4 m/s (Re˜ 36,000) and nozzle-plate spacing H/D=5. Helium-filled soap bubbles are used as tracer particles which are illuminated with pulsed LED arrays. A large measurement volume has been covered (cloud of tracked particles in a volume of 54 L, ˜ 180,000 particles). The reconstructed pressure field has been validated against microphone recordings at the wall with high correlation coefficients up to 0.88. In a reduced measurement volume (13 L), dense Lagrangian particle tracking is shown to be feasable up to the maximal possible jet velocity of U=16 m/s.

Particle identification algorithms for the PANDA Endcap Disc DIRC

NASA Astrophysics Data System (ADS)

Schmidt, M.; Ali, A.; Belias, A.; Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Kalicy, G.; Krebs, M.; Lehmann, D.; Nerling, F.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Böhm, M.; Eyrich, W.; Lehmann, A.; Pfaffinger, M.; Uhlig, F.; Düren, M.; Etzelmüller, E.; Föhl, K.; Hayrapetyan, A.; Kreutzfeld, K.; Merle, O.; Rieke, J.; Wasem, T.; Achenbach, P.; Cardinali, M.; Hoek, M.; Lauth, W.; Schlimme, S.; Sfienti, C.; Thiel, M.

2017-12-01

The Endcap Disc DIRC has been developed to provide an excellent particle identification for the future PANDA experiment by separating pions and kaons up to a momentum of 4 GeV/c with a separation power of 3 standard deviations in the polar angle region from 5o to 22o. This goal will be achieved using dedicated particle identification algorithms based on likelihood methods and will be applied in an offline analysis and online event filtering. This paper evaluates the resulting PID performance using Monte-Carlo simulations to study basic single track PID as well as the analysis of complex physics channels. The online reconstruction algorithm has been tested with a Virtex4 FGPA card and optimized regarding the resulting constraints.

Development of a real-time internal and external marker tracking system for particle therapy: a phantom study using patient tumor trajectory data

PubMed Central

Cho, Junsang; Cheon, Wonjoong; Ahn, Sanghee; Jung, Hyunuk; Sheen, Heesoon; Park, Hee Chul

2017-01-01

Abstract Target motion–induced uncertainty in particle therapy is more complicated than that in X-ray therapy, requiring more accurate motion management. Therefore, a hybrid motion-tracking system that can track internal tumor motion and as well as an external surrogate of tumor motion was developed. Recently, many correlation tests between internal and external markers in X-ray therapy have been developed; however, the accuracy of such internal/external marker tracking systems, especially in particle therapy, has not yet been sufficiently tested. In this article, the process of installing an in-house hybrid internal/external motion-tracking system is described and the accuracy level of tracking system was acquired. Our results demonstrated that the developed in-house external/internal combined tracking system has submillimeter accuracy, and can be clinically used as a particle therapy system as well as a simulation system for moving tumor treatment. PMID:28201522

High-speed particle tracking in microscopy using SPAD image sensors

NASA Astrophysics Data System (ADS)

Gyongy, Istvan; Davies, Amy; Miguelez Crespo, Allende; Green, Andrew; Dutton, Neale A. W.; Duncan, Rory R.; Rickman, Colin; Henderson, Robert K.; Dalgarno, Paul A.

2018-02-01

Single photon avalanche diodes (SPADs) are used in a wide range of applications, from fluorescence lifetime imaging microscopy (FLIM) to time-of-flight (ToF) 3D imaging. SPAD arrays are becoming increasingly established, combining the unique properties of SPADs with widefield camera configurations. Traditionally, the photosensitive area (fill factor) of SPAD arrays has been limited by the in-pixel digital electronics. However, recent designs have demonstrated that by replacing the complex digital pixel logic with simple binary pixels and external frame summation, the fill factor can be increased considerably. A significant advantage of such binary SPAD arrays is the high frame rates offered by the sensors (>100kFPS), which opens up new possibilities for capturing ultra-fast temporal dynamics in, for example, life science cellular imaging. In this work we consider the use of novel binary SPAD arrays in high-speed particle tracking in microscopy. We demonstrate the tracking of fluorescent microspheres undergoing Brownian motion, and in intra-cellular vesicle dynamics, at high frame rates. We thereby show how binary SPAD arrays can offer an important advance in live cell imaging in such fields as intercellular communication, cell trafficking and cell signaling.

PSO Algorithm Particle Filters for Improving the Performance of Lane Detection and Tracking Systems in Difficult Roads

PubMed Central

Cheng, Wen-Chang

2012-01-01

In this paper we propose a robust lane detection and tracking method by combining particle filters with the particle swarm optimization method. This method mainly uses the particle filters to detect and track the local optimum of the lane model in the input image and then seeks the global optimal solution of the lane model by a particle swarm optimization method. The particle filter can effectively complete lane detection and tracking in complicated or variable lane environments. However, the result obtained is usually a local optimal system status rather than the global optimal system status. Thus, the particle swarm optimization method is used to further refine the global optimal system status in all system statuses. Since the particle swarm optimization method is a global optimization algorithm based on iterative computing, it can find the global optimal lane model by simulating the food finding way of fish school or insects under the mutual cooperation of all particles. In verification testing, the test environments included highways and ordinary roads as well as straight and curved lanes, uphill and downhill lanes, lane changes, etc. Our proposed method can complete the lane detection and tracking more accurately and effectively then existing options. PMID:23235453

Two-Step Single Particle Mass Spectrometry for On-Line Monitoring of Polycyclic Aromatic Hydrocarbons Bound to Ambient Fine Particulate Matter

NASA Astrophysics Data System (ADS)

Zimmermann, R.; Bente, M.; Sklorz, M.

2007-12-01

Polycyclic aromatic hydrocarbons (PAH) are formed as trace products in combustion processes and are emitted to the atmosphere. Larger PAH have low vapour pressure and are predominantly bound to the ambient fine particulate matter (PM). Upon inhalation, PAH show both, chronic human toxicity (i.e. many PAH are potent carcinogens) as well as acute human toxicity (i.e. inflammatory effects due to oxi-dative stress) and are discussed to be relevant for the observed health effect of ambient PM. Therefore a better understanding of the occurrence, dynamics and particle size dependence of particle bound-PAH is of great interest. On-line aerosol mass spectrometry in principle is the method of choice to investigate the size resolved changes in the chemical speciation of particles as well the status of internal vs. external mixing of chemical constituents. However the present available aerosol mass spectrometers (ATOFMS and AMS) do not allow detection of PAH from ambient air PM. In order to allow a single particle based monitoring of PAH from ambient PM a new single particle laser ionisation mass spectrometer was built and applied. The system is based on ATOFMS principle but uses a two- step photo-ionization. A tracked and sized particle firstly is laser desorbed (LD) by a IR-laser pulse (CO2-laser, λ=10.2 μm) and subsequently the released PAH are selectively ionized by an intense UV-laser pulse (ArF excimer, λ=248 nm) in a resonance enhanced multiphoton ionisation process (REMPI). The PAH-ions are detected in a time of flight mass spectrometer (TOFMS). A virtual impactor enrichment unit is used to increase the detection frequency of the ambient particles. With the current inlet system particles from about 400 nm to 10 μm are accessible. Single particle based temporal profiles of PAH containing particles ion (size distribution and PAH speciation) have been recorded in Oberschleissheim, Germany from ambient air. Furthermore profiles of relevant emission sources (e.g. gasoline and diesel engine, wood combustion) and the obtained chemical profiles were compared with the ones from the ambient PAH containing particles.

Stardust Interstellar Preliminary Examination V: XRF Analyses of Interstellar Dust Candidates at ESRF ID13

NASA Technical Reports Server (NTRS)

Brenker, Frank E.; Westphal, Andrew J.; Simionovici, Alexandre S.; Flynn, George J.; Gainsforth, Zack; Allen, Carlton C.; Sanford, Scott; Zolensky, Michael E.; Bastien, Ron K.; Frank, David R.

2014-01-01

Here, we report analyses by synchrotron X-ray fluorescence microscopy of the elemental composition of eight candidate impact features extracted from the Stardust Interstellar Dust Collector (SIDC). Six of the features were unambiguous tracks, and two were crater-like features. Five of the tracks are so-called midnight tracks that is, they had trajectories consistent with an origin either in the interstellar dust stream or as secondaries from impacts on the Sample Return Capsule (SRC). In a companion paper reporting synchrotron X-ray diffraction analyses of ISPE candidates, we show that two of these particles contain natural crystalline materials: the terminal particle of track 30contains olivine and spinel, and the terminal particle of track 34 contains olivine. Here, we show that the terminal particle of track 30, Orion, shows elemental abundances, normalized to Fe, that are close to CI values, and a complex, fine-grained structure. The terminal particle of track 34, Hylabrook, shows abundances that deviate strongly from CI, but shows little fine structure and is nearly homogenous. The terminal particles of other midnight tracks, 29 and 37, had heavy element abundances below detection threshold. A third, track28, showed a composition inconsistent with an extraterrestrial origin, but also inconsistent with known spacecraft materials. A sixth track, with a trajectory consistent with secondary ejecta from an impact on one of the spacecraft solar panels, contains abundant Ce and Zn. This is consistent with the known composition of the glass covering the solar panel. Neither crater-like feature is likely to be associated with extraterrestrial materials. We also analyzed blank aerogel samples to characterize background and variability between aerogel tiles. We found significant differences in contamination levels and compositions, emphasizing the need for local background subtraction for accurate quantification.

Engineering cell-fluorescent ion track hybrid detectors.

PubMed

Niklas, Martin; Greilich, Steffen; Melzig, Claudius; Akselrod, Mark S; Debus, Jürgen; Jäkel, Oliver; Abdollahi, Amir

2013-06-11

The lack of sensitive biocompatible particle track detectors has so far limited parallel detection of physical energy deposition and biological response. Fluorescent nuclear track detectors (FNTDs) based on Al₂O₃:C,Mg single crystals combined with confocal laser scanning microscopy (CLSM) provide 3D information on ion tracks with a resolution limited by light diffraction. Here we report the development of next generation cell-fluorescent ion track hybrid detectors (Cell-Fit-HD). The biocompatibility of FNTDs was tested using six different cell lines, i.e. human non-small cell lung carcinoma (A549), glioblastoma (U87), androgen independent prostate cancer (PC3), epidermoid cancer (A431) and murine (VmDk) glioma SMA-560. To evaluate cell adherence, viability and conformal coverage of the crystals different seeding densities and alternative coating with extracellular matrix (fibronectin) was tested. Carbon irradiation was performed in Bragg peak (initial 270.55 MeV u⁻¹). A series of cell compartment specific fluorescence stains including nuclear (HOECHST), membrane (Glut-1), cytoplasm (Calcein AM, CM-DiI) were tested on Cell-Fit-HDs and a single CLSM was employed to co-detect the physical (crystal) as well as the biological (cell layer) information. The FNTD provides a biocompatible surface. Among the cells tested, A549 cells formed the most uniform, viable, tightly packed epithelial like monolayer. The ion track information was not compromised in Cell-Fit-HD as compared to the FNTD alone. Neither cell coating and culturing, nor additional staining procedures affected the properties of the FNTD surface to detect ion tracks. Standard immunofluorescence and live staining procedures could be employed to co-register cell biology and ion track information. The Cell-Fit-Hybrid Detector system is a promising platform for a multitude of studies linking biological response to energy deposition at high level of optical microscopy resolution.

Using Image Attributes to Assure Accurate Particle Size and Count Using Nanoparticle Tracking Analysis.

PubMed

Defante, Adrian P; Vreeland, Wyatt N; Benkstein, Kurt D; Ripple, Dean C

2018-05-01

Nanoparticle tracking analysis (NTA) obtains particle size by analysis of particle diffusion through a time series of micrographs and particle count by a count of imaged particles. The number of observed particles imaged is controlled by the scattering cross-section of the particles and by camera settings such as sensitivity and shutter speed. Appropriate camera settings are defined as those that image, track, and analyze a sufficient number of particles for statistical repeatability. Here, we test if image attributes, features captured within the image itself, can provide measurable guidelines to assess the accuracy for particle size and count measurements using NTA. The results show that particle sizing is a robust process independent of image attributes for model systems. However, particle count is sensitive to camera settings. Using open-source software analysis, it was found that a median pixel area, 4 pixels 2 , results in a particle concentration within 20% of the expected value. The distribution of these illuminated pixel areas can also provide clues about the polydispersity of particle solutions prior to using a particle tracking analysis. Using the median pixel area serves as an operator-independent means to assess the quality of the NTA measurement for count. Published by Elsevier Inc.

Markerless human motion tracking using hierarchical multi-swarm cooperative particle swarm optimization.

PubMed

Saini, Sanjay; Zakaria, Nordin; Rambli, Dayang Rohaya Awang; Sulaiman, Suziah

2015-01-01

The high-dimensional search space involved in markerless full-body articulated human motion tracking from multiple-views video sequences has led to a number of solutions based on metaheuristics, the most recent form of which is Particle Swarm Optimization (PSO). However, the classical PSO suffers from premature convergence and it is trapped easily into local optima, significantly affecting the tracking accuracy. To overcome these drawbacks, we have developed a method for the problem based on Hierarchical Multi-Swarm Cooperative Particle Swarm Optimization (H-MCPSO). The tracking problem is formulated as a non-linear 34-dimensional function optimization problem where the fitness function quantifies the difference between the observed image and a projection of the model configuration. Both the silhouette and edge likelihoods are used in the fitness function. Experiments using Brown and HumanEva-II dataset demonstrated that H-MCPSO performance is better than two leading alternative approaches-Annealed Particle Filter (APF) and Hierarchical Particle Swarm Optimization (HPSO). Further, the proposed tracking method is capable of automatic initialization and self-recovery from temporary tracking failures. Comprehensive experimental results are presented to support the claims.

Particle Tracking Model (PTM) with Coastal Modeling System (CMS)

DTIC Science & Technology

2015-11-04

Coastal Inlets Research Program Particle Tracking Model (PTM) with Coastal Modeling System ( CMS ) The Particle Tracking Model (PTM) is a Lagrangian...currents and waves. The Coastal Inlets Research Program (CIRP) supports the PTM with the Coastal Modeling System ( CMS ), which provides coupled wave...and current forcing for PTM simulations. CMS -PTM is implemented in the Surface-water Modeling System, a GUI environment for input development

Alpha particle spectroscopy using FNTD and SIM super-resolution microscopy.

PubMed

Kouwenberg, J J M; Kremers, G J; Slotman, J A; Wolterbeek, H T; Houtsmuller, A B; Denkova, A G; Bos, A J J

2018-06-01

Structured illumination microscopy (SIM) for the imaging of alpha particle tracks in fluorescent nuclear track detectors (FNTD) was evaluated and compared to confocal laser scanning microscopy (CLSM). FNTDs were irradiated with an external alpha source and imaged using both methodologies. SIM imaging resulted in improved resolution, without increase in scan time. Alpha particle energy estimation based on the track length, direction and intensity produced results in good agreement with the expected alpha particle energy distribution. A pronounced difference was seen in the spatial scattering of alpha particles in the detectors, where SIM showed an almost 50% reduction compared to CLSM. The improved resolution of SIM allows for more detailed studies of the tracks induced by ionising particles. The combination of SIM and FNTDs for alpha radiation paves the way for affordable and fast alpha spectroscopy and dosimetry. © 2018 The Authors. Journal of Microscopy published by JohnWiley & Sons Ltd on behalf of Royal Microscopical Society.

Scintillator-fiber charged particle track-imaging detector

NASA Technical Reports Server (NTRS)

Binns, W. R.; Israel, M. H.; Klarmann, J.

1983-01-01

A scintillator-fiber charged-particle track-imaging detector was developed using a bundle of square cross section plastic scintillator fiber optics, proximity focused onto an image intensified charge injection device (CID) camera. The tracks of charged particle penetrating into the scintillator fiber bundle are projected onto the CID camera and the imaging information is read out in video format. The detector was exposed to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei and images of their tracks were obtained. Details of the detector technique, properties of the tracks obtained, and preliminary range measurements of 15 MeV protons stopping in the fiber bundle are presented.

Latent uncertainties of the precalculated track Monte Carlo method

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

Renaud, Marc-André; Seuntjens, Jan; Roberge, David

Purpose: While significant progress has been made in speeding up Monte Carlo (MC) dose calculation methods, they remain too time-consuming for the purpose of inverse planning. To achieve clinically usable calculation speeds, a precalculated Monte Carlo (PMC) algorithm for proton and electron transport was developed to run on graphics processing units (GPUs). The algorithm utilizes pregenerated particle track data from conventional MC codes for different materials such as water, bone, and lung to produce dose distributions in voxelized phantoms. While PMC methods have been described in the past, an explicit quantification of the latent uncertainty arising from the limited numbermore » of unique tracks in the pregenerated track bank is missing from the paper. With a proper uncertainty analysis, an optimal number of tracks in the pregenerated track bank can be selected for a desired dose calculation uncertainty. Methods: Particle tracks were pregenerated for electrons and protons using EGSnrc and GEANT4 and saved in a database. The PMC algorithm for track selection, rotation, and transport was implemented on the Compute Unified Device Architecture (CUDA) 4.0 programming framework. PMC dose distributions were calculated in a variety of media and compared to benchmark dose distributions simulated from the corresponding general-purpose MC codes in the same conditions. A latent uncertainty metric was defined and analysis was performed by varying the pregenerated track bank size and the number of simulated primary particle histories and comparing dose values to a “ground truth” benchmark dose distribution calculated to 0.04% average uncertainty in voxels with dose greater than 20% of D{sub max}. Efficiency metrics were calculated against benchmark MC codes on a single CPU core with no variance reduction. Results: Dose distributions generated using PMC and benchmark MC codes were compared and found to be within 2% of each other in voxels with dose values greater than 20% of the maximum dose. In proton calculations, a small (≤1 mm) distance-to-agreement error was observed at the Bragg peak. Latent uncertainty was characterized for electrons and found to follow a Poisson distribution with the number of unique tracks per energy. A track bank of 12 energies and 60000 unique tracks per pregenerated energy in water had a size of 2.4 GB and achieved a latent uncertainty of approximately 1% at an optimal efficiency gain over DOSXYZnrc. Larger track banks produced a lower latent uncertainty at the cost of increased memory consumption. Using an NVIDIA GTX 590, efficiency analysis showed a 807 × efficiency increase over DOSXYZnrc for 16 MeV electrons in water and 508 × for 16 MeV electrons in bone. Conclusions: The PMC method can calculate dose distributions for electrons and protons to a statistical uncertainty of 1% with a large efficiency gain over conventional MC codes. Before performing clinical dose calculations, models to calculate dose contributions from uncharged particles must be implemented. Following the successful implementation of these models, the PMC method will be evaluated as a candidate for inverse planning of modulated electron radiation therapy and scanned proton beams.« less

Latent uncertainties of the precalculated track Monte Carlo method.

PubMed

Renaud, Marc-André; Roberge, David; Seuntjens, Jan

2015-01-01

While significant progress has been made in speeding up Monte Carlo (MC) dose calculation methods, they remain too time-consuming for the purpose of inverse planning. To achieve clinically usable calculation speeds, a precalculated Monte Carlo (PMC) algorithm for proton and electron transport was developed to run on graphics processing units (GPUs). The algorithm utilizes pregenerated particle track data from conventional MC codes for different materials such as water, bone, and lung to produce dose distributions in voxelized phantoms. While PMC methods have been described in the past, an explicit quantification of the latent uncertainty arising from the limited number of unique tracks in the pregenerated track bank is missing from the paper. With a proper uncertainty analysis, an optimal number of tracks in the pregenerated track bank can be selected for a desired dose calculation uncertainty. Particle tracks were pregenerated for electrons and protons using EGSnrc and geant4 and saved in a database. The PMC algorithm for track selection, rotation, and transport was implemented on the Compute Unified Device Architecture (cuda) 4.0 programming framework. PMC dose distributions were calculated in a variety of media and compared to benchmark dose distributions simulated from the corresponding general-purpose MC codes in the same conditions. A latent uncertainty metric was defined and analysis was performed by varying the pregenerated track bank size and the number of simulated primary particle histories and comparing dose values to a "ground truth" benchmark dose distribution calculated to 0.04% average uncertainty in voxels with dose greater than 20% of Dmax. Efficiency metrics were calculated against benchmark MC codes on a single CPU core with no variance reduction. Dose distributions generated using PMC and benchmark MC codes were compared and found to be within 2% of each other in voxels with dose values greater than 20% of the maximum dose. In proton calculations, a small (≤ 1 mm) distance-to-agreement error was observed at the Bragg peak. Latent uncertainty was characterized for electrons and found to follow a Poisson distribution with the number of unique tracks per energy. A track bank of 12 energies and 60000 unique tracks per pregenerated energy in water had a size of 2.4 GB and achieved a latent uncertainty of approximately 1% at an optimal efficiency gain over DOSXYZnrc. Larger track banks produced a lower latent uncertainty at the cost of increased memory consumption. Using an NVIDIA GTX 590, efficiency analysis showed a 807 × efficiency increase over DOSXYZnrc for 16 MeV electrons in water and 508 × for 16 MeV electrons in bone. The PMC method can calculate dose distributions for electrons and protons to a statistical uncertainty of 1% with a large efficiency gain over conventional MC codes. Before performing clinical dose calculations, models to calculate dose contributions from uncharged particles must be implemented. Following the successful implementation of these models, the PMC method will be evaluated as a candidate for inverse planning of modulated electron radiation therapy and scanned proton beams.

Elucidating distinct ion channel populations on the surface of hippocampal neurons via single-particle tracking recurrence analysis

NASA Astrophysics Data System (ADS)

Sikora, Grzegorz; Wyłomańska, Agnieszka; Gajda, Janusz; Solé, Laura; Akin, Elizabeth J.; Tamkun, Michael M.; Krapf, Diego

2017-12-01

Protein and lipid nanodomains are prevalent on the surface of mammalian cells. In particular, it has been recently recognized that ion channels assemble into surface nanoclusters in the soma of cultured neurons. However, the interactions of these molecules with surface nanodomains display a considerable degree of heterogeneity. Here, we investigate this heterogeneity and develop statistical tools based on the recurrence of individual trajectories to identify subpopulations within ion channels in the neuronal surface. We specifically study the dynamics of the K+ channel Kv1.4 and the Na+ channel Nav1.6 on the surface of cultured hippocampal neurons at the single-molecule level. We find that both these molecules are expressed in two different forms with distinct kinetics with regards to surface interactions, emphasizing the complex proteomic landscape of the neuronal surface. Further, the tools presented in this work provide new methods for the analysis of membrane nanodomains, transient confinement, and identification of populations within single-particle trajectories.

Tracking Virus Particles in Fluorescence Microscopy Images Using Multi-Scale Detection and Multi-Frame Association.

PubMed

Jaiswal, Astha; Godinez, William J; Eils, Roland; Lehmann, Maik Jorg; Rohr, Karl

2015-11-01

Automatic fluorescent particle tracking is an essential task to study the dynamics of a large number of biological structures at a sub-cellular level. We have developed a probabilistic particle tracking approach based on multi-scale detection and two-step multi-frame association. The multi-scale detection scheme allows coping with particles in close proximity. For finding associations, we have developed a two-step multi-frame algorithm, which is based on a temporally semiglobal formulation as well as spatially local and global optimization. In the first step, reliable associations are determined for each particle individually in local neighborhoods. In the second step, the global spatial information over multiple frames is exploited jointly to determine optimal associations. The multi-scale detection scheme and the multi-frame association finding algorithm have been combined with a probabilistic tracking approach based on the Kalman filter. We have successfully applied our probabilistic tracking approach to synthetic as well as real microscopy image sequences of virus particles and quantified the performance. We found that the proposed approach outperforms previous approaches.

Single-particle tracking and modulation of cell entry pathways of a tetrahedral DNA nanostructure in live cells.

PubMed

Liang, Le; Li, Jiang; Li, Qian; Huang, Qing; Shi, Jiye; Yan, Hao; Fan, Chunhai

2014-07-21

DNA is typically impermeable to the plasma membrane due to its polyanionic nature. Interestingly, several different DNA nanostructures can be readily taken up by cells in the absence of transfection agents, which suggests new opportunities for constructing intelligent cargo delivery systems from these biocompatible, nonviral DNA nanocarriers. However, the underlying mechanism of entry of the DNA nanostructures into the cells remains unknown. Herein, we investigated the endocytotic internalization and subsequent transport of tetrahedral DNA nanostructures (TDNs) by mammalian cells through single-particle tracking. We found that the TDNs were rapidly internalized by a caveolin-dependent pathway. After endocytosis, the TDNs were transported to the lysosomes in a highly ordered, microtubule-dependent manner. Although the TDNs retained their structural integrity within cells over long time periods, their localization in the lysosomes precludes their use as effective delivery agents. To modulate the cellular fate of the TDNs, we functionalized them with nuclear localization signals that directed their escape from the lysosomes and entry into the cellular nuclei. This study improves our understanding of the entry into cells and transport pathways of DNA nanostructures, and the results can be used as a basis for designing DNA-nanostructure-based drug delivery nanocarriers for targeted therapy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cosmic heavy ion tracks in mesoscopic biological test objects

NASA Technical Reports Server (NTRS)

Facius, R.

1994-01-01

Since more than 20 years ago, when the National Academy of Sciences and the National Research Council of the U.S.A. released their report on 'HZE particle effects in manned spaced flight', it has been emphasized how difficult - if not even impossible - it is to assess their radiobiological impact on man from conventional studies where biological test organisms are stochastically exposed to 'large' fluences of heavy ions. An alternative, competing approach had been realized in the BIOSTACK experiments, where the effects of single cosmic as well as accelerator - heavy ions on individual biological test organisms could be investigated. Although presented from the beginning as the preferable approach for terrestrial investigations with accelerator heavy ions too ('The BIOSTACK as an approach to high LET radiation research'), only recently this insight is gaining more widespread recognition. In space flight experiments, additional constraints imposed by the infrastructure of the vehicle or satellite further impede such investigations. Restrictions concern the physical detector systems needed for the registration of the cosmic heavy ions' trajectories as well as the biological systems eligible as test organisms. Such optimized procedures and techniques were developed for the investigations on chromosome aberrations induced by cosmic heavy ions in cells of the stem meristem of lettuce seeds (Lactuca sativa) and for the investigation of the radiobiological response of Wolffia arriza, which is the smallest flowering (water) plant. The biological effects were studied by the coworkers of the Russian Institute of Biomedical Problems (IBMP) which in cooperation with the European Space Agency ESA organized the exposure in the Biosatellites of the Cosmos series. Since biological investigations and physical measurements of particle tracks had to be performed in laboratories widely separated, the preferred fixed contact between biological test objects and the particle detectors until the geometrical correlation between tracks and organisms has been established could not be maintained. This gave rise to half a dozen of coordinate systems for different measurements which finally had to be related to a single stack reference system.

3D laser traking of a particle in 3DFM

NASA Astrophysics Data System (ADS)

Desai, Kalpit; Welch, Gregory; Bishop, Gary; Taylor, Russell; Superfine, Richard

2003-11-01

The principal goal of 3D tracking in our home-built 3D Magnetic Force Microscope is to monitor movement of the particle with respect to laser beam waist and keep the particle at the center of laser beam. The sensory element is a Quadrant Photo Diode (QPD) which captures scattering of light caused by particle motion with bandwidth up to 40 KHz. XYZ translation stage is the driver element which moves particle back in the center of the laser with accuracy of couple of nanometers and with bandwidth up to 300 Hz. Since our particles vary in size, composition and shape, instead of using a priori model we use standard system identification techniques to have optimal approximation to the relationship between particle motion and QPD response. We have developed position feedback control system software that is capable of 3-dimensional tracking of beads that are attached to cilia on living cells which are beating at up to 15Hz. We have also modeled the control system of instrument to simulate performance of 3D particle tracking for different experimental conditions. Given operational level of nanometers, noise poses a great challenge for the tracking system. We propose to use stochastic control theory approaches to increase robustness of tracking.

Infrared Spectroscopy of Wild 2 Particle Hypervelocity Tracks in Stardust Aerogel: Evidence for the presence of Volatile Organics in Comet Dust

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

Bajt, S; Sandford, S A; Flynn, G J

2007-08-28

Infrared spectroscopy maps of some tracks, made by cometary dust from 81P/Wild 2 impacting Stardust aerogel, reveal an interesting distribution of volatile organic material. Out of six examined tracks three show presence of volatile organic components possibly injected into the aerogel during particle impacts. When particle tracks contained excess volatile organic material, they were found to be -CH{sub 2}-rich. Off-normal particle tracks could indicate impacts by lower velocity particles that could have bounced off the Whipple shield, therefore carry off some contamination from it. However, this theory is not supported by data that show excess organic-rich material in normal andmore » off-normal particle tracks. It is clear that the population of cometary particles impacting the Stardust aerogel collectors also include grains that contained little or none of this volatile organic component. This observation is consistent with the highly heterogeneous nature of the collected grains, as seen by a multitude of other analytical techniques. We propose that at least some of the volatile organic material might be of cometary origin based on supporting data shown in this paper. However, we also acknowledge the presence of carbon (primarily as -CH{sub 3}) in the original aerogel, which complicates interpretation of these results.« less

Single particle tracking with sterol modulation reveals the cholesterol-mediated diffusion properties of integrin receptors.

PubMed

Arora, Neha; Syed, Aleem; Sander, Suzanne; Smith, Emily A

2014-10-07

A combination of sterol modulation with cyclodextrins plus fluorescence microscopy revealed a biophysical mechanism behind cholesterol's influence on the diffusion of a ubiquitous class of receptors called integrins. The heterogeneous diffusion of integrins bound to ligand-coated quantum dots was measured using single particle tracking (SPT), and the ensemble changes in integrin diffusion were measured by fluorescence recovery after photobleaching (FRAP). A 25 ± 1% reduction of membrane cholesterol resulted in three significant changes to the diffusion of ligand-bound αPS2CβPS integrins as measured by SPT. There was a 23% increase in ligand-bound mobile integrins; there was a statistically significant increase in the average diffusion coefficient inside zones of confined diffusion, and histograms of confined integrin trajectories showed an increased frequency in the range of 0.1-1 μm(2) s(-1) and a decreased frequency in the 0.001-0.1 μm(2) s(-1) range. No statistical change was measured in the duration of confinement nor the size of confined zones. Restoring the cholesterol-depleted cells with exogenous cholesterol or exogenous epicholesterol resulted in similar diffusion properties. Epicholesterol differs from cholesterol in the orientation of a single hydroxyl group. The ability of epicholesterol to substitute for cholesterol suggests a biophysical mechanism for cholesterol's effect on integrin diffusion. Influences of bilayer thickness, viscosity and organization are discussed as possible explanations for the measured changes in integrin diffusion when the membrane cholesterol concentration is reduced.

Particle Identification in Nuclear Emulsion by Measuring Multiple Coulomb Scattering

NASA Astrophysics Data System (ADS)

Than Tint, Khin; Nakazawa, Kazuma; Yoshida, Junya; Kyaw Soe, Myint; Mishina, Akihiro; Kinbara, Shinji; Itoh, Hiroki; Endo, Yoko; Kobayashi, Hidetaka; E07 Collaboration

2014-09-01

We are developing particle identification techniques for single charged particles such as Xi, proton, K and π by measuring multiple Coulomb scattering in nuclear emulsion. Nuclear emulsion is the best three dimensional detector for double strangeness (S = -2) nuclear system. We expect to accumulate about 10000 Xi-minus stop events which produce double lambda hypernucleus in J-PARC E07 emulsion counter hybrid experiment. The purpose of this particle identification (PID) in nuclear emulsion is to purify Xi-minus stop events which gives information about production probability of double hypernucleus and branching ratio of decay mode. Amount of scattering parameterized as angular distribution and second difference is inversely proportional to the momentum of particle. We produced several thousands of various charged particle tracks in nuclear emulsion stack via Geant4 simulation. In this talk, PID with some measuring methods for multiple scattering will be discussed by comparing with simulation data and real Xi-minus stop events in KEK-E373 experiment.

Biodegradable Magnetic Particles for Cellular MRI

NASA Astrophysics Data System (ADS)

Nkansah, Michael Kwasi

Cell transplantation has the potential to treat numerous diseases and injuries. While magnetic particle-enabled, MRI-based cell tracking has proven useful for visualizing the location of cell transplants in vivo, current formulations of particles are either too weak to enable single cell detection or have non-degradable polymer matrices that preclude clinical translation. Furthermore, the off-label use of commercial agents like Feridex®, Bangs beads and ferumoxytol for cell tracking significantly stunts progress in the field, rendering it needlessly susceptible to market externalities. The recent phasing out of Feridex from the market, for example, heightens the need for a dedicated agent specifically designed for MRI-based cell tracking. To this end, we engineered clinically viable, biodegradable particles of iron oxide made using poly(lactide-co-glycolide) (PLGA) and demonstrated their utility in two MRI-based cell tracking paradigms in vivo. Both micro- and nanoparticles (2.1±1.1 μm and 105±37 nm in size) were highly magnetic (56.7-83.7 wt% magnetite), and possessed excellent relaxometry (r2* relaxivities as high as 614.1 s-1mM-1 and 659.1 s -1mM-1 at 4.7 T respectively). Magnetic PLGA micropartides enabled the in vivo monitoring of neural progenitor cell migration to the olfactory bulb in rat brains over 2 weeks at 11.7 T with ˜2-fold greater contrast-to-noise ratio and ˜4-fold better sensitivity at detecting migrated cells in the olfactory bulb than Bangs beads. Highly magnetic PLGA nanoparticles enabled MRI detection (at 11.7 T) of up to 10 rat mesenchymal cells transplanted into rat brain at 100-μm resolution. Highly magnetic PLGA particles were also shown to degrade by 80% in mice liver over 12 weeks in vivo. Moreover, no adverse effects were observed on cellular viability and function in vitro after labeling a wide range of cells. Magnetically labeled rat mesenchymal and neural stem cells retained their ability to differentiate into multiple lineages. Particle-labeled bone marrow-derived mouse macrophages exhibited little to no immune response to particles and were still capable of normal TNF-α and IL-6 release upon stimulation by lipopolysaccharide. Minimal generation of reactive oxygen species was observed in mouse macrophages and embryonic fibroblasts labeled with particles. In addition, magnetic particles of cellulose and chitin (69.6 wt% and 52 wt% magnetite) were fabricated as more bioresponsive agents that could potentially relay richer information on cellular fate in vivo and enable sophisticated immunocellular investigations via MRI. Magnetic cellulose particles showed a 63% increase in r2 relaxivity and 15% increase in r2* relaxivity upon degradation by cellulase in vitro, consistent with theoretical predictions of relaxometry in the static dephasing regime for a particle of reduced size. Magnetofluorescent chitin nanoparticles efficiently labeled rat peripheral blood monocytes in vitro (72% labeling efficiency) with little adverse effect on viability (92% viability). This thesis describes the first clinically translatable agent specifically designed for MRI-based cell tracking with immediate implications for preclinical investigations in (stem) cell therapy.

Primary cosmic ray particles with Z greater than 35 /VVH particles/. [Very Very Heavy particle track measurement by balloons

NASA Technical Reports Server (NTRS)

Blanford, G. E., Jr.; Friedlander, M. W.; Hoppe, M.; Klarmann, J.; Walker, R. M.; Wefel, J. P.

1974-01-01

Large areas of nuclear emulsions and plastic detectors were exposed to the primary cosmic radiation during high-altitude balloon flights. From an analysis of 141 particle tracks recorded during a total exposure of 13,000,000 sq m-ster-sec, a charge spectrum of the VVH particles has been derived.

Integrating Geochemical Reactions with a Particle-Tracking Approach to Simulate Nitrogen Transport and Transformation in Aquifers

NASA Astrophysics Data System (ADS)

Cui, Z.; Welty, C.; Maxwell, R. M.

2011-12-01

Lagrangian, particle-tracking models are commonly used to simulate solute advection and dispersion in aquifers. They are computationally efficient and suffer from much less numerical dispersion than grid-based techniques, especially in heterogeneous and advectively-dominated systems. Although particle-tracking models are capable of simulating geochemical reactions, these reactions are often simplified to first-order decay and/or linear, first-order kinetics. Nitrogen transport and transformation in aquifers involves both biodegradation and higher-order geochemical reactions. In order to take advantage of the particle-tracking approach, we have enhanced an existing particle-tracking code SLIM-FAST, to simulate nitrogen transport and transformation in aquifers. The approach we are taking is a hybrid one: the reactive multispecies transport process is operator split into two steps: (1) the physical movement of the particles including the attachment/detachment to solid surfaces, which is modeled by a Lagrangian random-walk algorithm; and (2) multispecies reactions including biodegradation are modeled by coupling multiple Monod equations with other geochemical reactions. The coupled reaction system is solved by an ordinary differential equation solver. In order to solve the coupled system of equations, after step 1, the particles are converted to grid-based concentrations based on the mass and position of the particles, and after step 2 the newly calculated concentration values are mapped back to particles. The enhanced particle-tracking code is capable of simulating subsurface nitrogen transport and transformation in a three-dimensional domain with variably saturated conditions. Potential application of the enhanced code is to simulate subsurface nitrogen loading to the Chesapeake Bay and its tributaries. Implementation details, verification results of the enhanced code with one-dimensional analytical solutions and other existing numerical models will be presented in addition to a discussion of implementation challenges.

Reconstructing the flight kinematics of swarming and mating in wild mosquitoes

PubMed Central

Butail, Sachit; Manoukis, Nicholas; Diallo, Moussa; Ribeiro, José M.; Lehmann, Tovi; Paley, Derek A.

2012-01-01

We describe a novel tracking system for reconstructing three-dimensional tracks of individual mosquitoes in wild swarms and present the results of validating the system by filming swarms and mating events of the malaria mosquito Anopheles gambiae in Mali. The tracking system is designed to address noisy, low frame-rate (25 frames per second) video streams from a stereo camera system. Because flying A. gambiae move at 1–4 m s−1, they appear as faded streaks in the images or sometimes do not appear at all. We provide an adaptive algorithm to search for missing streaks and a likelihood function that uses streak endpoints to extract velocity information. A modified multi-hypothesis tracker probabilistically addresses occlusions and a particle filter estimates the trajectories. The output of the tracking algorithm is a set of track segments with an average length of 0.6–1 s. The segments are verified and combined under human supervision to create individual tracks up to the duration of the video (90 s). We evaluate tracking performance using an established metric for multi-target tracking and validate the accuracy using independent stereo measurements of a single swarm. Three-dimensional reconstructions of A. gambiae swarming and mating events are presented. PMID:22628212

Local characterization of hindered Brownian motion by using digital video microscopy and 3D particle tracking

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

Dettmer, Simon L.; Keyser, Ulrich F.; Pagliara, Stefano

In this article we present methods for measuring hindered Brownian motion in the confinement of complex 3D geometries using digital video microscopy. Here we discuss essential features of automated 3D particle tracking as well as diffusion data analysis. By introducing local mean squared displacement-vs-time curves, we are able to simultaneously measure the spatial dependence of diffusion coefficients, tracking accuracies and drift velocities. Such local measurements allow a more detailed and appropriate description of strongly heterogeneous systems as opposed to global measurements. Finite size effects of the tracking region on measuring mean squared displacements are also discussed. The use of thesemore » methods was crucial for the measurement of the diffusive behavior of spherical polystyrene particles (505 nm diameter) in a microfluidic chip. The particles explored an array of parallel channels with different cross sections as well as the bulk reservoirs. For this experiment we present the measurement of local tracking accuracies in all three axial directions as well as the diffusivity parallel to the channel axis while we observed no significant flow but purely Brownian motion. Finally, the presented algorithm is suitable also for tracking of fluorescently labeled particles and particles driven by an external force, e.g., electrokinetic or dielectrophoretic forces.« less

Development of a real-time internal and external marker tracking system for particle therapy: a phantom study using patient tumor trajectory data.

PubMed

Cho, Junsang; Cheon, Wonjoong; Ahn, Sanghee; Jung, Hyunuk; Sheen, Heesoon; Park, Hee Chul; Han, Youngyih

2017-09-01

Target motion-induced uncertainty in particle therapy is more complicated than that in X-ray therapy, requiring more accurate motion management. Therefore, a hybrid motion-tracking system that can track internal tumor motion and as well as an external surrogate of tumor motion was developed. Recently, many correlation tests between internal and external markers in X-ray therapy have been developed; however, the accuracy of such internal/external marker tracking systems, especially in particle therapy, has not yet been sufficiently tested. In this article, the process of installing an in-house hybrid internal/external motion-tracking system is described and the accuracy level of tracking system was acquired. Our results demonstrated that the developed in-house external/internal combined tracking system has submillimeter accuracy, and can be clinically used as a particle therapy system as well as a simulation system for moving tumor treatment. © The Author 2017. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

On the holographic 3D tracking of in vitro cells characterized by a highly-morphological change.

PubMed

Memmolo, Pasquale; Iannone, Maria; Ventre, Maurizio; Netti, Paolo Antonio; Finizio, Andrea; Paturzo, Melania; Ferraro, Pietro

2012-12-17

Digital Holography (DH) in microscopic configuration is a powerful tool for the imaging of micro-objects contained into a three dimensional (3D) volume, by a single-shot image acquisition. Many studies report on the ability of DH to track particle, microorganism and cells in 3D. However, very few investigations are performed with objects that change severely their morphology during the observation period. Here we study DH as a tool for 3D tracking an osteosarcoma cell line for which extensive changes in cell morphology are associated to cell motion. Due to the great unpredictable morphological change, retrieving cell's position in 3D can become a complicated issue. We investigate and discuss in this paper how the tridimensional position can be affected by the continuous change of the cells. Moreover we propose and test some strategies to afford the problems and compare it with others approaches. Finally, results on the 3D tracking and comments are reported and illustrated.

Multivalency of NDC80 in the outer kinetochore is essential to track shortening microtubules and generate forces

PubMed Central

2018-01-01

Presence of multiple copies of the microtubule-binding NDC80 complex is an evolutionary conserved feature of kinetochores, points of attachment of chromosomes to spindle microtubules. This may enable multivalent attachments to microtubules, with implications that remain unexplored. Using recombinant human kinetochore components, we show that while single NDC80 complexes do not track depolymerizing microtubules, reconstituted particles containing the NDC80 receptor CENP-T bound to three or more NDC80 complexes do so effectively, as expected for a kinetochore force coupler. To study multivalency systematically, we engineered modules allowing incremental addition of NDC80 complexes. The modules’ residence time on microtubules increased exponentially with the number of NDC80 complexes. Modules with two or more complexes tracked depolymerizing microtubules with increasing efficiencies, and stalled and rescued microtubule depolymerization in a force-dependent manner when conjugated to cargo. Our observations indicate that NDC80, rather than through biased diffusion, tracks depolymerizing microtubules by harnessing force generated during microtubule disassembly. PMID:29629870

Novel algorithm and MATLAB-based program for automated power law analysis of single particle, time-dependent mean-square displacement

NASA Astrophysics Data System (ADS)

Umansky, Moti; Weihs, Daphne

2012-08-01

In many physical and biophysical studies, single-particle tracking is utilized to reveal interactions, diffusion coefficients, active modes of driving motion, dynamic local structure, micromechanics, and microrheology. The basic analysis applied to those data is to determine the time-dependent mean-square displacement (MSD) of particle trajectories and perform time- and ensemble-averaging of similar motions. The motion of particles typically exhibits time-dependent power-law scaling, and only trajectories with qualitatively and quantitatively comparable MSD should be ensembled. Ensemble averaging trajectories that arise from different mechanisms, e.g., actively driven and diffusive, is incorrect and can result inaccurate correlations between structure, mechanics, and activity. We have developed an algorithm to automatically and accurately determine power-law scaling of experimentally measured single-particle MSD. Trajectories can then categorized and grouped according to user defined cutoffs of time, amplitudes, scaling exponent values, or combinations. Power-law fits are then provided for each trajectory alongside categorized groups of trajectories, histograms of power laws, and the ensemble-averaged MSD of each group. The codes are designed to be easily incorporated into existing user codes. We expect that this algorithm and program will be invaluable to anyone performing single-particle tracking, be it in physical or biophysical systems. Catalogue identifier: AEMD_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEMD_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 25 892 No. of bytes in distributed program, including test data, etc.: 5 572 780 Distribution format: tar.gz Programming language: MATLAB (MathWorks Inc.) version 7.11 (2010b) or higher, program should also be backwards compatible. Symbolic Math Toolboxes (5.5) is required. The Curve Fitting Toolbox (3.0) is recommended. Computer: Tested on Windows only, yet should work on any computer running MATLAB. In Windows 7, should be used as administrator, if the user is not the administrator the program may not be able to save outputs and temporary outputs to all locations. Operating system: Any supporting MATLAB (MathWorks Inc.) v7.11 / 2010b or higher. Supplementary material: Sample output files (approx. 30 MBytes) are available. Classification: 12 External routines: Several MATLAB subfunctions (m-files), freely available on the web, were used as part of and included in, this code: count, NaN suite, parseArgs, roundsd, subaxis, wcov, wmean, and the executable pdfTK.exe. Nature of problem: In many physical and biophysical areas employing single-particle tracking, having the time-dependent power-laws governing the time-averaged meansquare displacement (MSD) of a single particle is crucial. Those power laws determine the mode-of-motion and hint at the underlying mechanisms driving motion. Accurate determination of the power laws that describe each trajectory will allow categorization into groups for further analysis of single trajectories or ensemble analysis, e.g. ensemble and time-averaged MSD. Solution method: The algorithm in the provided program automatically analyzes and fits time-dependent power laws to single particle trajectories, then group particles according to user defined cutoffs. It accepts time-dependent trajectories of several particles, each trajectory is run through the program, its time-averaged MSD is calculated, and power laws are determined in regions where the MSD is linear on a log-log scale. Our algorithm searches for high-curvature points in experimental data, here time-dependent MSD. Those serve as anchor points for determining the ranges of the power-law fits. Power-law scaling is then accurately determined and error estimations of the parameters and quality of fit are provided. After all single trajectory time-averaged MSDs are fit, we obtain cutoffs from the user to categorize and segment the power laws into groups; cutoff are either in exponents of the power laws, time of appearance of the fits, or both together. The trajectories are sorted according to the cutoffs and the time- and ensemble-averaged MSD of each group is provided, with histograms of the distributions of the exponents in each group. The program then allows the user to generate new trajectory files with trajectories segmented according to the determined groups, for any further required analysis. Additional comments: README file giving the names and a brief description of all the files that make-up the package and clear instructions on the installation and execution of the program is included in the distribution package. Running time: On an i5 Windows 7 machine with 4 GB RAM the automated parts of the run (excluding data loading and user input) take less than 45 minutes to analyze and save all stages for an 844 trajectory file, including optional PDF save. Trajectory length did not affect run time (tested up to 3600 frames/trajectory), which was on average 3.2±0.4 seconds per trajectory.

Assessment of the pseudo-tracking approach for the calculation of material acceleration and pressure fields from time-resolved PIV: part I. Error propagation

NASA Astrophysics Data System (ADS)

van Gent, P. L.; Schrijer, F. F. J.; van Oudheusden, B. W.

2018-04-01

Pseudo-tracking refers to the construction of imaginary particle paths from PIV velocity fields and the subsequent estimation of the particle (material) acceleration. In view of the variety of existing and possible alternative ways to perform the pseudo-tracking method, it is not straightforward to select a suitable combination of numerical procedures for its implementation. To address this situation, this paper extends the theoretical framework for the approach. The developed theory is verified by applying various implementations of pseudo-tracking to a simulated PIV experiment. The findings of the investigations allow us to formulate the following insights and practical recommendations: (1) the velocity errors along the imaginary particle track are primarily a function of velocity measurement errors and spatial velocity gradients; (2) the particle path may best be calculated with second-order accurate numerical procedures while ensuring that the CFL condition is met; (3) least-square fitting of a first-order polynomial is a suitable method to estimate the material acceleration from the track; and (4) a suitable track length may be selected on the basis of the variation in material acceleration with track length.

Tracking of Ball and Players in Beach Volleyball Videos

PubMed Central

Gomez, Gabriel; Herrera López, Patricia; Link, Daniel; Eskofier, Bjoern

2014-01-01

This paper presents methods for the determination of players' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points. PMID:25426936

A hand tracking algorithm with particle filter and improved GVF snake model

NASA Astrophysics Data System (ADS)

Sun, Yi-qi; Wu, Ai-guo; Dong, Na; Shao, Yi-zhe

2017-07-01

To solve the problem that the accurate information of hand cannot be obtained by particle filter, a hand tracking algorithm based on particle filter combined with skin-color adaptive gradient vector flow (GVF) snake model is proposed. Adaptive GVF and skin color adaptive external guidance force are introduced to the traditional GVF snake model, guiding the curve to quickly converge to the deep concave region of hand contour and obtaining the complex hand contour accurately. This algorithm realizes a real-time correction of the particle filter parameters, avoiding the particle drift phenomenon. Experimental results show that the proposed algorithm can reduce the root mean square error of the hand tracking by 53%, and improve the accuracy of hand tracking in the case of complex and moving background, even with a large range of occlusion.

Single molecule tracking

DOEpatents

Shera, E. Brooks

1988-01-01

A detection system is provided for identifying individual particles or molecules having characteristic emission in a flow train of the particles in a flow cell. A position sensitive sensor is located adjacent the flow cell in a position effective to detect the emissions from the particles within the flow cell and to assign spatial and temporal coordinates for the detected emissions. A computer is then enabled to predict spatial and temporal coordinates for the particle in the flow train as a function of a first detected emission. Comparison hardware or software then compares subsequent detected spatial and temporal coordinates with the predicted spatial and temporal coordinates to determine whether subsequently detected emissions originate from a particle in the train of particles. In one embodiment, the particles include fluorescent dyes which are excited to fluoresce a spectrum characteristic of the particular particle. Photones are emitted adjacent at least one microchannel plate sensor to enable spatial and temporal coordinates to be assigned. The effect of comparing detected coordinates with predicted coordinates is to define a moving sample volume which effectively precludes the effects of background emissions.

Single molecule tracking

DOEpatents

Shera, E.B.

1987-10-07

A detection system is provided for identifying individual particles or molecules having characteristic emission in a flow train of the particles in a flow cell. A position sensitive sensor is located adjacent the flow cell in a position effective to detect the emissions from the particles within the flow cell and to assign spatial and temporal coordinates for the detected emissions. A computer is then enabled to predict spatial and temporal coordinates for the particle in the flow train as a function of a first detected emission. Comparison hardware or software then compares subsequent detected spatial and temporal coordinates with the predicted spatial and temporal coordinates to determine whether subsequently detected emissions originate from a particle in the train of particles. In one embodiment, the particles include fluorescent dyes which are excited to fluoresce a spectrum characteristic of the particular particle. Photons are emitted adjacent at least one microchannel plate sensor to enable spatial and temporal coordinates to be assigned. The effect of comparing detected coordinates with predicted coordinates is to define a moving sample volume which effectively precludes the effects of background emissions. 3 figs.

The effects of delta rays on the number of particle-track traversals per cell in laboratory and space exposures

NASA Technical Reports Server (NTRS)

Cucinotta, F. A.; Nikjoo, H.; Goodhead, D. T.; Wilson, J. W. (Principal Investigator)

1998-01-01

It is a common practice to estimate the number of particle-track traversals per cell or cell nucleus as the product of the ion's linear energy transfer (LET) and cell area. This practice ignores the effects of track width due to the lateral extension of delta rays. We make estimates of the number of particle-track traversals per cell, which includes the effects of delta rays using radial cutoffs in the ionization density about an ion's track of 1 mGy and 1 cGy. Calculations for laboratory and space radiation exposures are discussed, and show that the LET approximation provides a large underestimate of the actual number of particle-track traversals per cell from high-charge and energy (HZE) ions. In light of the current interest in the mechanisms of radiation action, including signal transduction and cytoplasmic damage, these results should be of interest for radiobiology studies with HZE ions.

Three dimensional reconstruction of therapeutic carbon ion beams in phantoms using single secondary ion tracks

NASA Astrophysics Data System (ADS)

Reinhart, Anna Merle; Spindeldreier, Claudia Katharina; Jakubek, Jan; Martišíková, Mária

2017-06-01

Carbon ion beam radiotherapy enables a very localised dose deposition. However, even small changes in the patient geometry or positioning errors can significantly distort the dose distribution. A live, non-invasive monitoring system of the beam delivery within the patient is therefore highly desirable, and could improve patient treatment. We present a novel three-dimensional method for imaging the beam in the irradiated object, exploiting the measured tracks of single secondary ions emerging under irradiation. The secondary particle tracks are detected with a TimePix stack—a set of parallel pixelated semiconductor detectors. We developed a three-dimensional reconstruction algorithm based on maximum likelihood expectation maximization. We demonstrate the applicability of the new method in the irradiation of a cylindrical PMMA phantom of human head size with a carbon ion pencil beam of {226} MeV u-1. The beam image in the phantom is reconstructed from a set of nine discrete detector positions between {-80}^\\circ and {50}^\\circ from the beam axis. Furthermore, we demonstrate the potential to visualize inhomogeneities by irradiating a PMMA phantom with an air gap as well as bone and adipose tissue surrogate inserts. We successfully reconstructed a three-dimensional image of the treatment beam in the phantom from single secondary ion tracks. The beam image corresponds well to the beam direction and energy. In addition, cylindrical inhomogeneities with a diameter of {2.85} cm and density differences down to {0.3} g cm-3 to the surrounding material are clearly visualized. This novel three-dimensional method to image a therapeutic carbon ion beam in the irradiated object does not interfere with the treatment and requires knowledge only of single secondary ion tracks. Even with detectors with only a small angular coverage, the three-dimensional reconstruction of the fragmentation points presented in this work was found to be feasible.

Three dimensional reconstruction of therapeutic carbon ion beams in phantoms using single secondary ion tracks.

PubMed

Reinhart, Anna Merle; Spindeldreier, Claudia Katharina; Jakubek, Jan; Martišíková, Mária

2017-06-21

Carbon ion beam radiotherapy enables a very localised dose deposition. However, even small changes in the patient geometry or positioning errors can significantly distort the dose distribution. A live, non-invasive monitoring system of the beam delivery within the patient is therefore highly desirable, and could improve patient treatment. We present a novel three-dimensional method for imaging the beam in the irradiated object, exploiting the measured tracks of single secondary ions emerging under irradiation. The secondary particle tracks are detected with a TimePix stack-a set of parallel pixelated semiconductor detectors. We developed a three-dimensional reconstruction algorithm based on maximum likelihood expectation maximization. We demonstrate the applicability of the new method in the irradiation of a cylindrical PMMA phantom of human head size with a carbon ion pencil beam of [Formula: see text] MeV u -1 . The beam image in the phantom is reconstructed from a set of nine discrete detector positions between [Formula: see text] and [Formula: see text] from the beam axis. Furthermore, we demonstrate the potential to visualize inhomogeneities by irradiating a PMMA phantom with an air gap as well as bone and adipose tissue surrogate inserts. We successfully reconstructed a three-dimensional image of the treatment beam in the phantom from single secondary ion tracks. The beam image corresponds well to the beam direction and energy. In addition, cylindrical inhomogeneities with a diameter of [Formula: see text] cm and density differences down to [Formula: see text] g cm -3 to the surrounding material are clearly visualized. This novel three-dimensional method to image a therapeutic carbon ion beam in the irradiated object does not interfere with the treatment and requires knowledge only of single secondary ion tracks. Even with detectors with only a small angular coverage, the three-dimensional reconstruction of the fragmentation points presented in this work was found to be feasible.

Detection limit of a VCO based detection chain dedicated to particles recognition and tracking

NASA Astrophysics Data System (ADS)

Coulié, K.; Rahajandraibe, W.; Aziza, H.; Micolau, G.; Vauché, R.

2018-01-01

A particle detection chain based on CMOS-SOI VCO circuit is presented. The solution is used for the recognition and the tracking of a given particle at circuit level. TCAD simulation of the detector has been performed on a 3×3 matrix of diodes based detector for particles recognition and tracking. The current response of the detector has been used for a case study in order to determine the ability of the chain to recognize an alpha particle crossing a 3×3 detection cell. The detection limit of the proposed solution is investigated and discussed in this paper.

Track-structure simulations for charged particles.

PubMed

Dingfelder, Michael

2012-11-01

Monte Carlo track-structure simulations provide a detailed and accurate picture of radiation transport of charged particles through condensed matter of biological interest. Liquid water serves as a surrogate for soft tissue and is used in most Monte Carlo track-structure codes. Basic theories of radiation transport and track-structure simulations are discussed and differences compared to condensed history codes highlighted. Interaction cross sections for electrons, protons, alpha particles, and light and heavy ions are required input data for track-structure simulations. Different calculation methods, including the plane-wave Born approximation, the dielectric theory, and semi-empirical approaches are presented using liquid water as a target. Low-energy electron transport and light ion transport are discussed as areas of special interest.

Label-free tracking of single extracellular vesicles in a nano-fluidic optical fiber (Conference Presentation)

NASA Astrophysics Data System (ADS)

van der Pol, Edwin; Weidlich, Stefan; Lahini, Yoav; Coumans, Frank A. W.; Sturk, Auguste; Nieuwland, Rienk; Schmidt, Markus A.; Faez, Sanli; van Leeuwen, Ton G.

2016-03-01

Background: Extracellular vesicles, such as exosomes, are abundantly present in human body fluids. Since the size, concentration and composition of these vesicles change during disease, vesicles have promising clinical applications, including cancer diagnosis. However, since ~70% of the vesicles have a diameter <70 nm, detection of single vesicles remains challenging. Thus far, vesicles <70 nm have only be studied by techniques that require the vesicles to be adhered to a surface. Consequently, the majority of vesicles have never been studied in their physiological environment. We present a novel label-free optical technique to track single vesicles <70 nm in suspension. Method: Urinary vesicles were contained within a single-mode light-guiding silica fiber containing a 600 nm nano-fluidic channel. Light from a diode laser (660 nm wavelength) was coupled to the fiber, resulting in a strongly confined optical mode in the nano-fluidic channel, which continuously illuminated the freely diffusing vesicles inside the channel. The elastic light scattering from the vesicles, in the direction orthogonal to the fiber axis, was collected using a microscope objective (NA=0.95) and imaged with a home-built microscope. Results: We have tracked single urinary vesicles as small as 35 nm by elastic light scattering. Please note that vesicles are low-refractive index (n<1.4) particles, which we confirmed by combining data on thermal diffusion and light scattering cross section. Conclusions: For the first time, we have studied vesicles <70 nm freely diffusing in suspension. The ease-of-use and performance of this technique support its potential for vesicle-based clinical applications.

Two particle tracking and detection in a single Gaussian beam optical trap.

PubMed

Praveen, P; Yogesha; Iyengar, Shruthi S; Bhattacharya, Sarbari; Ananthamurthy, Sharath

2016-01-20

We have studied in detail the situation wherein two microbeads are trapped axially in a single-beam Gaussian intensity profile optical trap. We find that the corner frequency extracted from a power spectral density analysis of intensity fluctuations recorded on a quadrant photodetector (QPD) is dependent on the detection scheme. Using forward- and backscattering detection schemes with single and two laser wavelengths along with computer simulations, we conclude that fluctuations detected in backscattering bear true position information of the bead encountered first in the beam propagation direction. Forward scattering, on the other hand, carries position information of both beads with substantial contribution from the bead encountered first along the beam propagation direction. Mie scattering analysis further reveals that the interference term from the scattering of the two beads contributes significantly to the signal, precluding the ability to resolve the positions of the individual beads in forward scattering. In QPD-based detection schemes, detection through backscattering, thereby, is imperative to track the true displacements of axially trapped microbeads for possible studies on light-mediated interbead interactions.

Simulation of zones of contribution to wells at site GM–38, Naval Weapons Industrial Reserve Plant, Bethpage, New York

USGS Publications Warehouse

Misut, Paul

2014-01-01

A three-dimensional groundwater-flow model is coupled with the particle-tracking program MODPATH to delineate zones of contribution to wells pumping from the Magothy aquifer and supplying water to a chlorinated volatile organic compound removal plant at site GM–38, Naval Weapons Industrial Reserve Plant, Bethpage, New York. By use of driller’s logs, a transitional probability approach generated three alternative realizations of heterogeneity within the Magothy aquifer to assess uncertainty in model representation. Finer-grained sediments with low hydraulic conductivity were realized as laterally discontinuous, thickening towards the south, and comprising about 17 percent of the total aquifer volume. Particle-tracking evaluations of a steady state present conditions model with alternative heterogeneity realizations were used to develop zones of contribution of remedial pumping wells. Because of heterogeneity and high rates of advection within the coarse-grained sediments, transport by dispersion and (or) diffusion was assumed to be negligible. Resulting zones of contribution of existing remedial wells are complex shapes, influenced by heterogeneity of each realization and other nearby hydrologic stresses. The use of two particle tracking techniques helped identify zones of contribution to wells. Backtracking techniques and observations of points of intersection of backward-tracked particles at shells of the GM–38 Hot Spot, as defined by surfaces of equal total volatile organic compound concentration, identified the source of water within the GM–38 Hot Spot to simulated wells. Forward-tracking techniques identified the fate of water within the GM–38 Hot Spot, including well capture and discharge to model constant head and drain boundaries. The percentage of backward-tracked particles, started at GM–38 wells that were sourced from within the Hot Spot, varied from 72.0 to 98.2, depending on the Hot Spot delineation used (present steady state model and Magothy aquifer heterogeneity realization A). The percentage of forward-tracked particles that were captured by GM–38 wells varied from 81.1 to 94.6, depending on the Hot Spot delineation used, with the remainder primarily captured by Bethpage Water District Plant 4 production wells (present steady state model and Magothy aquifer heterogeneity realization A). Less than 1 percent of forward-tracked particles ultimately discharge at model constant head and drain boundaries. The differences between forward- and backward-tracked particle percentage ranges are due to some forward-tracked particles not being captured by GM–38 wells, and some backward-tracked particles not intersecting specific regions of the Hot Spot. During 2013, an aquifer test generated detailed time series of well pumping rates and corresponding water-level responses were recorded at numerous locations. These data were used to verify the present conditions steady state model and demonstrate the sensitivity of model results to transient-state changes.

Tracking individual membrane proteins and their biochemistry: The power of direct observation.

PubMed

Barden, Adam O; Goler, Adam S; Humphreys, Sara C; Tabatabaei, Samaneh; Lochner, Martin; Ruepp, Marc-David; Jack, Thomas; Simonin, Jonathan; Thompson, Andrew J; Jones, Jeffrey P; Brozik, James A

2015-11-01

The advent of single molecule fluorescence microscopy has allowed experimental molecular biophysics and biochemistry to transcend traditional ensemble measurements, where the behavior of individual proteins could not be precisely sampled. The recent explosion in popularity of new super-resolution and super-localization techniques coupled with technical advances in optical designs and fast highly sensitive cameras with single photon sensitivity and millisecond time resolution have made it possible to track key motions, reactions, and interactions of individual proteins with high temporal resolution and spatial resolution well beyond the diffraction limit. Within the purview of membrane proteins and ligand gated ion channels (LGICs), these outstanding advances in single molecule microscopy allow for the direct observation of discrete biochemical states and their fluctuation dynamics. Such observations are fundamentally important for understanding molecular-level mechanisms governing these systems. Examples reviewed here include the effects of allostery on the stoichiometry of ligand binding in the presence of fluorescent ligands; the observation of subdomain partitioning of membrane proteins due to microenvironment effects; and the use of single particle tracking experiments to elucidate characteristics of membrane protein diffusion and the direct measurement of thermodynamic properties, which govern the free energy landscape of protein dimerization. The review of such characteristic topics represents a snapshot of efforts to push the boundaries of fluorescence microscopy of membrane proteins to the absolute limit. This article is part of the Special Issue entitled 'Fluorescent Tools in Neuropharmacology'. Copyright © 2015 Elsevier Ltd. All rights reserved.

Aerogel Track Morphology: Measurement, Three Dimensional Reconstruction and Particle Location using Confocal Laser Scanning Microscopy

NASA Technical Reports Server (NTRS)

Kearsley, A. T.; Ball, A. D.; Wozniakiewicz, P. A.; Graham, G. A.; Burchell, M. J.; Cole, M. J.; Horz, F.; See, T. H.

2007-01-01

The Stardust spacecraft returned the first undoubted samples of cometary dust, with many grains embedded in the silica aerogel collector . Although many tracks contain one or more large terminal particles of a wide range of mineral compositions , there is also abundant material along the track walls. To help interpret the full particle size, structure and mass, both experimental simulation of impact by shots and numerical modeling of the impact process have been attempted. However, all approaches require accurate and precise measurement of impact track size parameters such as length, width and volume of specific portions. To make such measurements is not easy, especially if extensive aerogel fracturing and discoloration has occurred. In this paper we describe the application and limitations of laser confocal imagery for determination of aerogel track parameters, and for the location of particle remains.

Stardust Interstellar Preliminary Examination IX: High-Speed Interstellar Dust Analog Capture in Stardust Flight-Spare Aerogel

NASA Technical Reports Server (NTRS)

Postberg, F.; Sterken, V.; Achilles, C.; Allen, C.; Bastien, R. K.; Frank, D.; Sandford, S. A.; Zolensky, M. E.; Butterworth, A.; Gainesforth, Z.

2014-01-01

The NASA Stardust mission used silica aerogel slabs to slowly decelerate and capture impinging cosmic dust particles for return to Earth. During this process, impact tracks are generated along the trajectory of the particle into the aerogel. It is believed that the morphology and dimensions of these tracks, together with the state of captured grains at track termini, may be linked to the size, velocity, and density of the impacting cosmic dust grain. Here, we present the results of laboratory hypervelocity impact experiments, during which cosmic dust analog particles (diameters of between 0.2 and 0.4 lm), composed of olivine, orthopyroxene, or an organic polymer, were accelerated onto Stardust flight spare low-density (approximately 0.01 g/cu cm) silica aerogel. The impact velocities (3-21 km/s) were chosen to simulate the range of velocities expected during Stardust's interstellar dust (ISD) collection phases. Track lengths and widths, together with the success of particle capture, are analyzed as functions of impact velocity and particle composition, density, and size. Captured terminal particles from low-density organic projectiles become undetectable at lower velocities than those from similarly sized, denser mineral particles, which are still detectable (although substantially altered by the impact process) at 15 km/s. The survival of these terminal particles, together with the track dimensions obtained during low impact speed capture of small grains in the laboratory, indicates that two of the three best Stardust candidate extraterrestrial grains were actually captured at speeds much lower than predicted. Track length and diameters are, in general, more sensitive to impact velocities than previously expected, which makes tracks of particles with diameters of 0.4 lm and below hard to identify at low capture speeds (<10 km/s). Therefore, although captured intact, the majority of the interstellar dust grains returned to Earth by Stardust remain to be found.

1- and 2-particle Microrheology of Hyaluronic Acid

NASA Astrophysics Data System (ADS)

Sagan, Austin; Kearns, Sarah; Ross, David; Das, Moumita; Thurston, George; Franklin, Scott

2015-03-01

Hyaluronic acid (also called HA or Hyaluronan) is a high molecular weight polysaccaride ubiquitous in the extracellular matrix of soft tissue such as cartilage, skin, the eye's vitreous gel and synovial fluid. It has been shown to play an important role in mechanotransduction, cell migration and proliferation, and in tissue morphodynamics. We present a confocal microrheology study of hyaluronic acid of varying concentrations. The mean squared displacement (MSD) of sub-micron colloidal tracer particles is tracked in two dimensions and shows a transition from diffusive motion at low concentrations to small-time trapping by the protein network as the concentration increases. Correlations between particle motion can be used to determine an effective mean-squared displacement which deviates from the single-particle MSD as the fluid becomes less homogeneous. The real and effective mean-squared displacements are used to probe the local and space-averaged frequency dependent rheological properties of the fluid as the concentration changes.

Luminescent sensors for tracking spatial particle distributions in an explosion

NASA Astrophysics Data System (ADS)

Anderson, Benjamin R.; Gunawidjaja, Ray; Diez-y-Riega, Helena; Eilers, Hergen; Svingala, Forrest R.; Daniels, Amber; Lightstone, James M.

2017-01-01

We previously developed and tested thermally sensitive particles that, when seeded into an explosive event, flow with the expanding post-detonation fireball and provide ex-situ measurements of this thermal environment. This current work presents the development and testing of tracking particles that are used in concert with the thermally sensitive particles to encode the initial positions of materials recovered for ex-situ analysis. These tracking sensors consist of fully-crystallized (c) rare-earth-doped yttria particles such as c-Dy:Y2O3, c-Sm:Y2O3, and c-Er,Yb:Y2O3. The temperature sensors consist of mixtures of precursor (p) and fully crystallized materials such as p-Eu:Y2O3/c-Tb:Y2O3 or p-Eu:ZrO2. Three mixtures containing one of the tracking sensors and one of the temperature sensing mixtures are placed at different locations within the chamber. Post-detonation, the tracking particles in the debris are excited by 355 nm light, resulting in different color luminescence, and allowing for potential visual inspection of the particle distribution originating from the different locations. Meanwhile, the temperature is determined from spectral changes of the precursor sensor materials or by comparison of the precursor sensor materials with the Tb:Y2O3 intensity reference.

Correlation of Particle Traversals with Clonogenic Survival Using Cell-Fluorescent Ion Track Hybrid Detector.

PubMed

Dokic, Ivana; Niklas, Martin; Zimmermann, Ferdinand; Mairani, Andrea; Seidel, Philipp; Krunic, Damir; Jäkel, Oliver; Debus, Jürgen; Greilich, Steffen; Abdollahi, Amir

2015-01-01

Development of novel approaches linking the physical characteristics of particles with biological responses are of high relevance for the field of particle therapy. In radiobiology, the clonogenic survival of cells is considered the gold standard assay for the assessment of cellular sensitivity to ionizing radiation. Toward further development of next generation biodosimeters in particle therapy, cell-fluorescent ion track hybrid detector (Cell-FIT-HD) was recently engineered by our group and successfully employed to study physical particle track information in correlation with irradiation-induced DNA damage in cell nuclei. In this work, we investigated the feasibility of Cell-FIT-HD as a tool to study the effects of clinical beams on cellular clonogenic survival. Tumor cells were grown on the fluorescent nuclear track detector as cell culture, mimicking the standard procedures for clonogenic assay. Cell-FIT-HD was used to detect the spatial distribution of particle tracks within colony-initiating cells. The physical data were associated with radiation-induced foci as surrogates for DNA double-strand breaks, the hallmark of radiation-induced cell lethality. Long-term cell fate was monitored to determine the ability of cells to form colonies. We report the first successful detection of particle traversal within colony-initiating cells at subcellular resolution using Cell-FIT-HD.

Photon event distribution sampling: an image formation technique for scanning microscopes that permits tracking of sub-diffraction particles with high spatial and temporal resolutions.

PubMed

Larkin, J D; Publicover, N G; Sutko, J L

2011-01-01

In photon event distribution sampling, an image formation technique for scanning microscopes, the maximum likelihood position of origin of each detected photon is acquired as a data set rather than binning photons in pixels. Subsequently, an intensity-related probability density function describing the uncertainty associated with the photon position measurement is applied to each position and individual photon intensity distributions are summed to form an image. Compared to pixel-based images, photon event distribution sampling images exhibit increased signal-to-noise and comparable spatial resolution. Photon event distribution sampling is superior to pixel-based image formation in recognizing the presence of structured (non-random) photon distributions at low photon counts and permits use of non-raster scanning patterns. A photon event distribution sampling based method for localizing single particles derived from a multi-variate normal distribution is more precise than statistical (Gaussian) fitting to pixel-based images. Using the multi-variate normal distribution method, non-raster scanning and a typical confocal microscope, localizations with 8 nm precision were achieved at 10 ms sampling rates with acquisition of ~200 photons per frame. Single nanometre precision was obtained with a greater number of photons per frame. In summary, photon event distribution sampling provides an efficient way to form images when low numbers of photons are involved and permits particle tracking with confocal point-scanning microscopes with nanometre precision deep within specimens. © 2010 The Authors Journal of Microscopy © 2010 The Royal Microscopical Society.

Tracking Water Diffusion Fronts in a Highly Viscous Aerosol Particle

NASA Astrophysics Data System (ADS)

Bastelberger, Sandra; Krieger, Ulrich; Peter, Thomas

2016-04-01

Field measurements indicate that atmospheric secondary aerosol particles can be present in a highly viscous, glassy state [1]. In contrast to liquid state particles, the gas phase equilibration is kinetically limited and governed by condensed phase diffusion. In recent water diffusion experiments on highly viscous single aerosol particles levitated in an electrodynamic balance (EDB) we observed a characteristic shift behavior of the Mie whispering gallery modes (WGM) indicative of the changing radial structure of the particle, thus providing us with an experimental method to track the diffusion process inside the particle. When a highly viscous, homogeneous particle is exposed to an abrupt increase in relative humidity, the rapid gas phase diffusion and strong concentration dependence of the diffusion coefficient in the condensed phase lead to extremely steep water concentration gradients inside the particle, reminiscent of diffusion fronts. The resulting quasi step-like concentration profile motivates the introduction of a simple core-shell model describing the morphology of the non-equilibrium particle during humidification. The subsequent particle growth and reduction of the shell refractive index can be observed as red and blueshift behavior of the WGM, respectively. The shift pattern can be attributed to a core-shell radius ratio and particle radius derived from model calculations [2]. If supplemented with growth information obtained from the WGM redshift and thermodynamic equilibrium data, we can infer a comprehensive picture of the time evolution of the diffusion fronts in the framework of our core-shell model. The measured time dependent concentration profile is then compared with simulations solving the non-linear diffusion equation [3] [1] Virtanen, A., et al., Nature, 467, 824-827, 2010 [2] Kaiser, T., Schweiger, G., Computers in Physics, Vol. 7, No. 6, 682-686, Nov/Dec 1993 [3] Zobrist, B., Soonsin, V., Luo, B.P., Peter, T. et al., Phys. Chem. Chem. Phys., 13,3514-3526, 2011

Method of and apparatus for measuring the mean concentration of thoron and/or radon in a gas mixture

DOEpatents

Lucas, Henry

1990-01-01

A method of and an apparatus for detecting and accurately measuring the mean concentrations of .sup.222 Rn and .sup.220 Tn in a gas mixture, such as the ambient atmosphere in a mine, is provided. The apparatus includes an alpha target member which defines at least one operative target surface and which is preferably fabricated from a single piece of an alpha particle sensitive material. At least one portion of the operative target surface is covered with an alpha particle filter. The uncovered and filter covered operative surface is exposed to the gas mixture containing the .sup.222 Rn and .sup.220 Tn. In the radioactive decay series of these isotopes the maximum kinetic energy emitted by the alpha decay of .sup.222 Rn is about 1.1 MeV less than the maximum kinetic energy emitted by the alpha decay of a .sup.220 Tn. The alpha particle filter has a predetermined mass per unit area of the covered portion of the operative target surface that prevents penetration of alpha particles which originate from .sup.222 Rn decay, but which allows passage therethrough of the maximum kinetic energy alpha particles from .sup.220 Tn decay. Thus, a count of the alpha particle tracks in the uncovered portion of the target member is proportional to the mean concentration of sum of .sup.222 Rn and .sup.220 Tn in the gas mixture, while the count of alpha tracks in the target member under the filter is proportional to the concentration of only the .sup.220 Tn in the gas mixture.

A Novel Multi-Sensor Environmental Perception Method Using Low-Rank Representation and a Particle Filter for Vehicle Reversing Safety

PubMed Central

Zhang, Zutao; Li, Yanjun; Wang, Fubing; Meng, Guanjun; Salman, Waleed; Saleem, Layth; Zhang, Xiaoliang; Wang, Chunbai; Hu, Guangdi; Liu, Yugang

2016-01-01

Environmental perception and information processing are two key steps of active safety for vehicle reversing. Single-sensor environmental perception cannot meet the need for vehicle reversing safety due to its low reliability. In this paper, we present a novel multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety. The proposed system consists of four main steps, namely multi-sensor environmental perception, information fusion, target recognition and tracking using low-rank representation and a particle filter, and vehicle reversing speed control modules. First of all, the multi-sensor environmental perception module, based on a binocular-camera system and ultrasonic range finders, obtains the distance data for obstacles behind the vehicle when the vehicle is reversing. Secondly, the information fusion algorithm using an adaptive Kalman filter is used to process the data obtained with the multi-sensor environmental perception module, which greatly improves the robustness of the sensors. Then the framework of a particle filter and low-rank representation is used to track the main obstacles. The low-rank representation is used to optimize an objective particle template that has the smallest L-1 norm. Finally, the electronic throttle opening and automatic braking is under control of the proposed vehicle reversing control strategy prior to any potential collisions, making the reversing control safer and more reliable. The final system simulation and practical testing results demonstrate the validity of the proposed multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety. PMID:27294931

A Novel Multi-Sensor Environmental Perception Method Using Low-Rank Representation and a Particle Filter for Vehicle Reversing Safety.

PubMed

Zhang, Zutao; Li, Yanjun; Wang, Fubing; Meng, Guanjun; Salman, Waleed; Saleem, Layth; Zhang, Xiaoliang; Wang, Chunbai; Hu, Guangdi; Liu, Yugang

2016-06-09

Environmental perception and information processing are two key steps of active safety for vehicle reversing. Single-sensor environmental perception cannot meet the need for vehicle reversing safety due to its low reliability. In this paper, we present a novel multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety. The proposed system consists of four main steps, namely multi-sensor environmental perception, information fusion, target recognition and tracking using low-rank representation and a particle filter, and vehicle reversing speed control modules. First of all, the multi-sensor environmental perception module, based on a binocular-camera system and ultrasonic range finders, obtains the distance data for obstacles behind the vehicle when the vehicle is reversing. Secondly, the information fusion algorithm using an adaptive Kalman filter is used to process the data obtained with the multi-sensor environmental perception module, which greatly improves the robustness of the sensors. Then the framework of a particle filter and low-rank representation is used to track the main obstacles. The low-rank representation is used to optimize an objective particle template that has the smallest L-1 norm. Finally, the electronic throttle opening and automatic braking is under control of the proposed vehicle reversing control strategy prior to any potential collisions, making the reversing control safer and more reliable. The final system simulation and practical testing results demonstrate the validity of the proposed multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety.

Test of the diffusing-diffusivity mechanism using near-wall colloidal dynamics

NASA Astrophysics Data System (ADS)

Matse, Mpumelelo; Chubynsky, Mykyta V.; Bechhoefer, John

2017-10-01

The mechanism of diffusing diffusivity predicts that, in environments where the diffusivity changes gradually, the displacement distribution becomes non-Gaussian, even though the mean-square displacement grows linearly with time. Here, we report single-particle tracking measurements of the diffusion of colloidal spheres near a planar substrate. Because the local effective diffusivity is known, we have been able to carry out a direct test of this mechanism for diffusion in inhomogeneous media.

Multiscale spectral nanoscopy

DOEpatents

Yang, Haw; Welsher, Kevin

2016-11-15

A system and method for non-invasively tracking a particle in a sample is disclosed. The system includes a 2-photon or confocal laser scanning microscope (LSM) and a particle-holding device coupled to a stage with X-Y and Z position control. The system also includes a tracking module having a tracking excitation laser, X-Y and Z radiation-gathering components configured to detect deviations of the particle in an X-Y and Z directions. The system also includes a processor coupled to the X-Y and Z radiation gathering components, generate control signals configured to drive the stage X-Y and Z position controls to track the movement of the particle. The system may also include a synchronization module configured to generate LSM pixels stamped with stage position and a processing module configured to generate a 3D image showing the 3D trajectory of a particle using the LSM pixels stamped with stage position.

Nanometer-scale anatomy of entire Stardust tracks

NASA Astrophysics Data System (ADS)

Nakamura-Messenger, Keiko; Keller, Lindsay P.; Clemett, Simon J.; Messenger, Scott; Ito, Motoo

2011-07-01

We have developed new sample preparation and analytical techniques tailored for entire aerogel tracks of Wild 2 sample analyses both on "carrot" and "bulbous" tracks. We have successfully ultramicrotomed an entire track along its axis while preserving its original shape. This innovation allowed us to examine the distribution of fragments along the entire track from the entrance hole all the way to the terminal particle. The crystalline silicates we measured have Mg-rich compositions and O isotopic compositions in the range of meteoritic materials, implying that they originated in the inner solar system. The terminal particle of the carrot track is a 16O-rich forsteritic grain that may have formed in a similar environment as Ca-, Al-rich inclusions and amoeboid olivine aggregates in primitive carbonaceous chondrites. The track also contains submicron-sized diamond grains likely formed in the solar system. Complex aromatic hydrocarbons distributed along aerogel tracks and in terminal particles. These organics are likely cometary but affected by shock heating.

UmUTracker: A versatile MATLAB program for automated particle tracking of 2D light microscopy or 3D digital holography data

NASA Astrophysics Data System (ADS)

Zhang, Hanqing; Stangner, Tim; Wiklund, Krister; Rodriguez, Alvaro; Andersson, Magnus

2017-10-01

We present a versatile and fast MATLAB program (UmUTracker) that automatically detects and tracks particles by analyzing video sequences acquired by either light microscopy or digital in-line holographic microscopy. Our program detects the 2D lateral positions of particles with an algorithm based on the isosceles triangle transform, and reconstructs their 3D axial positions by a fast implementation of the Rayleigh-Sommerfeld model using a radial intensity profile. To validate the accuracy and performance of our program, we first track the 2D position of polystyrene particles using bright field and digital holographic microscopy. Second, we determine the 3D particle position by analyzing synthetic and experimentally acquired holograms. Finally, to highlight the full program features, we profile the microfluidic flow in a 100 μm high flow chamber. This result agrees with computational fluid dynamic simulations. On a regular desktop computer UmUTracker can detect, analyze, and track multiple particles at 5 frames per second for a template size of 201 ×201 in a 1024 × 1024 image. To enhance usability and to make it easy to implement new functions we used object-oriented programming. UmUTracker is suitable for studies related to: particle dynamics, cell localization, colloids and microfluidic flow measurement. Program Files doi : http://dx.doi.org/10.17632/fkprs4s6xp.1 Licensing provisions : Creative Commons by 4.0 (CC by 4.0) Programming language : MATLAB Nature of problem: 3D multi-particle tracking is a common technique in physics, chemistry and biology. However, in terms of accuracy, reliable particle tracking is a challenging task since results depend on sample illumination, particle overlap, motion blur and noise from recording sensors. Additionally, the computational performance is also an issue if, for example, a computationally expensive process is executed, such as axial particle position reconstruction from digital holographic microscopy data. Versatile robust tracking programs handling these concerns and providing a powerful post-processing option are significantly limited. Solution method: UmUTracker is a multi-functional tool to extract particle positions from long video sequences acquired with either light microscopy or digital holographic microscopy. The program provides an easy-to-use graphical user interface (GUI) for both tracking and post-processing that does not require any programming skills to analyze data from particle tracking experiments. UmUTracker first conduct automatic 2D particle detection even under noisy conditions using a novel circle detector based on the isosceles triangle sampling technique with a multi-scale strategy. To reduce the computational load for 3D tracking, it uses an efficient implementation of the Rayleigh-Sommerfeld light propagation model. To analyze and visualize the data, an efficient data analysis step, which can for example show 4D flow visualization using 3D trajectories, is included. Additionally, UmUTracker is easy to modify with user-customized modules due to the object-oriented programming style Additional comments: Program obtainable from https://sourceforge.net/projects/umutracker/

Droplet morphometry and velocimetry (DMV): a video processing software for time-resolved, label-free tracking of droplet parameters.

PubMed

Basu, Amar S

2013-05-21

Emerging assays in droplet microfluidics require the measurement of parameters such as drop size, velocity, trajectory, shape deformation, fluorescence intensity, and others. While micro particle image velocimetry (μPIV) and related techniques are suitable for measuring flow using tracer particles, no tool exists for tracking droplets at the granularity of a single entity. This paper presents droplet morphometry and velocimetry (DMV), a digital video processing software for time-resolved droplet analysis. Droplets are identified through a series of image processing steps which operate on transparent, translucent, fluorescent, or opaque droplets. The steps include background image generation, background subtraction, edge detection, small object removal, morphological close and fill, and shape discrimination. A frame correlation step then links droplets spanning multiple frames via a nearest neighbor search with user-defined matching criteria. Each step can be individually tuned for maximum compatibility. For each droplet found, DMV provides a time-history of 20 different parameters, including trajectory, velocity, area, dimensions, shape deformation, orientation, nearest neighbour spacing, and pixel statistics. The data can be reported via scatter plots, histograms, and tables at the granularity of individual droplets or by statistics accrued over the population. We present several case studies from industry and academic labs, including the measurement of 1) size distributions and flow perturbations in a drop generator, 2) size distributions and mixing rates in drop splitting/merging devices, 3) efficiency of single cell encapsulation devices, 4) position tracking in electrowetting operations, 5) chemical concentrations in a serial drop dilutor, 6) drop sorting efficiency of a tensiophoresis device, 7) plug length and orientation of nonspherical plugs in a serpentine channel, and 8) high throughput tracking of >250 drops in a reinjection system. Performance metrics show that highest accuracy and precision is obtained when the video resolution is >300 pixels per drop. Analysis time increases proportionally with video resolution. The current version of the software provides throughputs of 2-30 fps, suggesting the potential for real time analysis.

Resolving occlusion and segmentation errors in multiple video object tracking

NASA Astrophysics Data System (ADS)

Cheng, Hsu-Yung; Hwang, Jenq-Neng

2009-02-01

In this work, we propose a method to integrate the Kalman filter and adaptive particle sampling for multiple video object tracking. The proposed framework is able to detect occlusion and segmentation error cases and perform adaptive particle sampling for accurate measurement selection. Compared with traditional particle filter based tracking methods, the proposed method generates particles only when necessary. With the concept of adaptive particle sampling, we can avoid degeneracy problem because the sampling position and range are dynamically determined by parameters that are updated by Kalman filters. There is no need to spend time on processing particles with very small weights. The adaptive appearance for the occluded object refers to the prediction results of Kalman filters to determine the region that should be updated and avoids the problem of using inadequate information to update the appearance under occlusion cases. The experimental results have shown that a small number of particles are sufficient to achieve high positioning and scaling accuracy. Also, the employment of adaptive appearance substantially improves the positioning and scaling accuracy on the tracking results.

Angle only tracking with particle flow filters

NASA Astrophysics Data System (ADS)

Daum, Fred; Huang, Jim

2011-09-01

We show the results of numerical experiments for tracking ballistic missiles using only angle measurements. We compare the performance of an extended Kalman filter with a new nonlinear filter using particle flow to compute Bayes' rule. For certain difficult geometries, the particle flow filter is an order of magnitude more accurate than the EKF. Angle only tracking is of interest in several different sensors; for example, passive optics and radars in which range and Doppler data are spoiled by jamming.

Passive non-linear microrheology for determining extensional viscosity

NASA Astrophysics Data System (ADS)

Hsiao, Kai-Wen; Dinic, Jelena; Ren, Yi; Sharma, Vivek; Schroeder, Charles M.

2017-12-01

Extensional viscosity is a key property of complex fluids that greatly influences the non-equilibrium behavior and processing of polymer solutions, melts, and colloidal suspensions. In this work, we use microfluidics to determine steady extensional viscosity for polymer solutions by directly observing particle migration in planar extensional flow. Tracer particles are suspended in semi-dilute solutions of DNA and polyethylene oxide, and a Stokes trap is used to confine single particles in extensional flows of polymer solutions in a cross-slot device. Particles are observed to migrate in the direction transverse to flow due to normal stresses, and particle migration is tracked and quantified using a piezo-nanopositioning stage during the microfluidic flow experiment. Particle migration trajectories are then analyzed using a second-order fluid model that accurately predicts that migration arises due to normal stress differences. Using this analytical framework, extensional viscosities can be determined from particle migration experiments, and the results are in reasonable agreement with bulk rheological measurements of extensional viscosity based on a dripping-onto-substrate method. Overall, this work demonstrates that non-equilibrium properties of complex fluids can be determined by passive yet non-linear microrheology.

Image Restoration and Analysis of Influenza Virions Binding to Membrane Receptors Reveal Adhesion-Strengthening Kinetics

PubMed Central

Lee, Donald W.; Hsu, Hung-Lun; Bacon, Kaitlyn B.; Daniel, Susan

2016-01-01

With the development of single-particle tracking (SPT) microscopy and host membrane mimics called supported lipid bilayers (SLBs), stochastic virus-membrane binding interactions can be studied in depth while maintaining control over host receptor type and concentration. However, several experimental design challenges and quantitative image analysis limitations prevent the widespread use of this approach. One main challenge of SPT studies is the low signal-to-noise ratio of SPT videos, which is sometimes inevitable due to small particle sizes, low quantum yield of fluorescent dyes, and photobleaching. These situations could render current particle tracking software to yield biased binding kinetic data caused by intermittent tracking error. Hence, we developed an effective image restoration algorithm for SPT applications called STAWASP that reveals particles with a signal-to-noise ratio of 2.2 while preserving particle features. We tested our improvements to the SPT binding assay experiment and imaging procedures by monitoring X31 influenza virus binding to α2,3 sialic acid glycolipids. Our interests lie in how slight changes to the peripheral oligosaccharide structures can affect the binding rate and residence times of viruses. We were able to detect viruses binding weakly to a glycolipid called GM3, which was undetected via assays such as surface plasmon resonance. The binding rate was around 28 folds higher when the virus bound to a different glycolipid called GD1a, which has a sialic acid group extending further away from the bilayer surface than GM3. The improved imaging allowed us to obtain binding residence time distributions that reflect an adhesion-strengthening mechanism via multivalent bonds. We empirically fitted these distributions using a time-dependent unbinding rate parameter, koff, which diverges from standard treatment of koff as a constant. We further explain how to convert these models to fit ensemble-averaged binding data obtained by assays such as surface plasmon resonance. PMID:27695072

Chasing Ghosts in Space Radiobiology Research: The Lost Focus on Non-Targeted Effects

NASA Astrophysics Data System (ADS)

Cucinotta, Francis; Saganti, Premkumar; Cacao, Eliedonna

2016-07-01

The doses and dose-rates of astronaut exposures to galactic cosmic rays (GCR) are accurately known, and lead to particle hits per cell nucleus from high charge and energy (HZE) particles of much less than one hit per cell per week. A large number of experiments have shown that additivity of biological effects is a valid assumption for space radiation exposures, while experiments at higher doses and dose-rates than occur in space continue to be a focus of the majority of space radiobiology research. Furthermore HZE particle exposures with mono-energetic particles manifest themselves as a mixed-radiation field due to the contributions of delta-rays and the random impact parameter of a particles track core to DNA and non-DNA targets in cells and tissues. The mixed-field manifestation of mono-energetic HZE particle exposures is well known from theoretical studies of microdosimetry and track structure. Additional mixed-field effects occur for single species experiments due to nuclear fragmentation in particle accelerator beam-lines and biological samples along with energy straggling. In contrast to these well known aspects of space radiobiology there are many open questions on the contribution of non-targeted effects to low dose and dose-rate exposures. Non-targeted effects (NTEs) include bystander effects and genomic instability, and have been shown to be the most important outstanding question for reducing uncertainties in space radiation cancer risk assessment. The dose-rate and radiation quality dependence of NTE's has not been established, while there is an over-arching need to develop 21st century experimental models of human cancer risk. We review possible mechanisms of NTE's and how new experiments to address these issues could be designed.

Direct visualization of nanoparticle dynamics at liquid interfaces

NASA Astrophysics Data System (ADS)

Gao, Yige; Kim, Paul; Hoagland, David; Russell, Tom

Ionic liquids, because of their negligible vapor pressures and moderate viscosities, are suitable media to investigate the dynamics of different types of dispersed nanoparticles by scanning electron microscopy. No liquid cell is necessary. Here, Brownian motions of nanoparticles partially wetted at the vacuum-liquid interface are visualized by low voltage SEM under conditions that allow single particle tracking for tens-of-minutes or longer. Conductive, nonconductive, semiconductive, and core-shell conductive-nonconductive nanoparticles have all been studied, and their interactions with each other in one- and two-component layers, as manifested in particle trajectories, differ significantly. For example, Au-coated silica nanoparticles aggregate above a threshold current, whereas aggregated silica-coated Au nanoparticles disaggregate at the same conditions. The impacts of surface concentration of nanoparticle dynamics were observed for one-component and two-component layers, with both global and localized motions visualized for single particles even in dense environments. As the surface concentration increases, the diffusion coefficient drops, and when the concentration reaches a critical threshold, the nanoparticles are essentially frozen. Financial support from NSF DMR-1619651 is acknowledged.

Impact of morphology on diffusive dynamics on curved surfaces

NASA Astrophysics Data System (ADS)

Kusters, Remy; Storm, Cornelis

2014-03-01

Diffusive processes on nonplanar substrates are deeply relevant for cellular function and transport and increasingly used to probe and characterize the behavior of proteins in membranes. We present analytical and numerical analyses of in-plane diffusion of discrete particles on curved geometries reflecting various generic motifs in biology and explore, in particular, the effect that the shape of the substrate has on the characteristic time scales of diffusive processes. To this end, we consider both collective measures (the relaxation of concentration profiles towards equilibrium) and single-particle measures (escape rates and first passage times of individual diffusing molecules): the first relevant for the correct interpretation of FRAP experiments in curved environments; the second, for single-particle tracking probes. Each of these measures is sensitively affected by the morphology of the substrate, and we find that the exit rate out of a domain is not uniquely set by the size of its boundary, illustrating the general principle we reveal: By varying the shape of a substrate, Nature can control the diffusive time scales in a microenvironment without changing the bare substrate properties.

Measuring molecular motions inside single cells with improved analysis of single-particle trajectories

NASA Astrophysics Data System (ADS)

Rowland, David J.; Biteen, Julie S.

2017-04-01

Single-molecule super-resolution imaging and tracking can measure molecular motions inside living cells on the scale of the molecules themselves. Diffusion in biological systems commonly exhibits multiple modes of motion, which can be effectively quantified by fitting the cumulative probability distribution of the squared step sizes in a two-step fitting process. Here we combine this two-step fit into a single least-squares minimization; this new method vastly reduces the total number of fitting parameters and increases the precision with which diffusion may be measured. We demonstrate this Global Fit approach on a simulated two-component system as well as on a mixture of diffusing 80 nm and 200 nm gold spheres to show improvements in fitting robustness and localization precision compared to the traditional Local Fit algorithm.

3D Rainbow Particle Tracking Velocimetry

NASA Astrophysics Data System (ADS)

Aguirre-Pablo, Andres A.; Xiong, Jinhui; Idoughi, Ramzi; Aljedaani, Abdulrahman B.; Dun, Xiong; Fu, Qiang; Thoroddsen, Sigurdur T.; Heidrich, Wolfgang

2017-11-01

A single color camera is used to reconstruct a 3D-3C velocity flow field. The camera is used to record the 2D (X,Y) position and colored scattered light intensity (Z) from white polyethylene tracer particles in a flow. The main advantage of using a color camera is the capability of combining different intensity levels for each color channel to obtain more depth levels. The illumination system consists of an LCD projector placed perpendicularly to the camera. Different intensity colored level gradients are projected onto the particles to encode the depth position (Z) information of each particle, benefiting from the possibility of varying the color profiles and projected frequencies up to 60 Hz. Chromatic aberrations and distortions are estimated and corrected using a 3D laser engraved calibration target. The camera-projector system characterization is presented considering size and depth position of the particles. The use of these components reduces dramatically the cost and complexity of traditional 3D-PTV systems.

Beam-induced motion correction for sub-megadalton cryo-EM particles.

PubMed

Scheres, Sjors Hw

2014-08-13

In electron cryo-microscopy (cryo-EM), the electron beam that is used for imaging also causes the sample to move. This motion blurs the images and limits the resolution attainable by single-particle analysis. In a previous Research article (Bai et al., 2013) we showed that correcting for this motion by processing movies from fast direct-electron detectors allowed structure determination to near-atomic resolution from 35,000 ribosome particles. In this Research advance article, we show that an improved movie processing algorithm is applicable to a much wider range of specimens. The new algorithm estimates straight movement tracks by considering multiple particles that are close to each other in the field of view, and models the fall-off of high-resolution information content by radiation damage in a dose-dependent manner. Application of the new algorithm to four data sets illustrates its potential for significantly improving cryo-EM structures, even for particles that are smaller than 200 kDa. Copyright © 2014, Scheres.

High-speed DNA-based rolling motors powered by RNase H

PubMed Central

Yehl, Kevin; Mugler, Andrew; Vivek, Skanda; Liu, Yang; Zhang, Yun; Fan, Mengzhen; Weeks, Eric R.

2016-01-01

DNA-based machines that walk by converting chemical energy into controlled motion could be of use in applications such as next generation sensors, drug delivery platforms, and biological computing. Despite their exquisite programmability, DNA-based walkers are, however, challenging to work with due to their low fidelity and slow rates (~1 nm/min). Here, we report DNA-based machines that roll rather than walk, and consequently have a maximum speed and processivity that is three-orders of magnitude greater than conventional DNA motors. The motors are made from DNA-coated spherical particles that hybridise to a surface modified with complementary RNA; motion is achieved through the addition of RNase H, which selectively hydrolyses hybridised RNA. Spherical motors move in a self-avoiding manner, whereas anisotropic particles, such as dimerised particles or rod-shaped particles travel linearly without a track or external force. Finally, we demonstrate detection of single nucleotide polymorphism by measuring particle displacement using a smartphone camera. PMID:26619152

Microrheometric upconversion-based techniques for intracellular viscosity measurements

NASA Astrophysics Data System (ADS)

Rodríguez-Sevilla, Paloma; Zhang, Yuhai; de Sousa, Nuno; Marqués, Manuel I.; Sanz-Rodríguez, Francisco; Jaque, Daniel; Liu, Xiaogang; Haro-González, Patricia

2017-08-01

Rheological parameters (viscosity, creep compliance and elasticity) play an important role in cell function and viability. For this reason different strategies have been developed for their study. In this work, two new microrheometric techniques are presented. Both methods take advantage of the analysis of the polarized emission of an upconverting particle to determine its orientation inside the optical trap. Upconverting particles are optical materials that are able to convert infrared radiation into visible light. Their usefulness has been further boosted by the recent demonstration of their three-dimensional control and tracking by single beam infrared optical traps. In this work it is demonstrated that optical torques are responsible of the stable orientation of the upconverting particle inside the trap. Moreover, numerical calculations and experimental data allowed to use the rotation dynamics of the optically trapped upconverting particle for environmental sensing. In particular, the cytoplasm viscosity could be measured by using the rotation time and thermal fluctuations of an intracellular optically trapped upconverting particle, by means of the two previously mentioned microrheometric techniques.

Viral Membrane Fusion and Nucleocapsid Delivery into the Cytoplasm are Distinct Events in Some Flaviviruses

PubMed Central

Nour, Adel M.; Li, Yue; Wolenski, Joseph; Modis, Yorgo

2013-01-01

Flaviviruses deliver their genome into the cell by fusing the viral lipid membrane to an endosomal membrane. The sequence and kinetics of the steps required for nucleocapsid delivery into the cytoplasm remain unclear. Here we dissect the cell entry pathway of virions and virus-like particles from two flaviviruses using single-particle tracking in live cells, a biochemical membrane fusion assay and virus infectivity assays. We show that the virus particles fuse with a small endosomal compartment in which the nucleocapsid remains trapped for several minutes. Endosomal maturation inhibitors inhibit infectivity but not membrane fusion. We propose a flavivirus cell entry mechanism in which the virus particles fuse preferentially with small endosomal carrier vesicles and depend on back-fusion of the vesicles with the late endosomal membrane to deliver the nucleocapsid into the cytoplasm. Virus entry modulates intracellular calcium release and phosphatidylinositol-3-phosphate kinase signaling. Moreover, the broadly cross-reactive therapeutic antibody scFv11 binds to virus-like particles and inhibits fusion. PMID:24039574

The new approach for infrared target tracking based on the particle filter algorithm

NASA Astrophysics Data System (ADS)

Sun, Hang; Han, Hong-xia

2011-08-01

Target tracking on the complex background in the infrared image sequence is hot research field. It provides the important basis in some fields such as video monitoring, precision, and video compression human-computer interaction. As a typical algorithms in the target tracking framework based on filtering and data connection, the particle filter with non-parameter estimation characteristic have ability to deal with nonlinear and non-Gaussian problems so it were widely used. There are various forms of density in the particle filter algorithm to make it valid when target occlusion occurred or recover tracking back from failure in track procedure, but in order to capture the change of the state space, it need a certain amount of particles to ensure samples is enough, and this number will increase in accompany with dimension and increase exponentially, this led to the increased amount of calculation is presented. In this paper particle filter algorithm and the Mean shift will be combined. Aiming at deficiencies of the classic mean shift Tracking algorithm easily trapped into local minima and Unable to get global optimal under the complex background. From these two perspectives that "adaptive multiple information fusion" and "with particle filter framework combining", we expand the classic Mean Shift tracking framework .Based on the previous perspective, we proposed an improved Mean Shift infrared target tracking algorithm based on multiple information fusion. In the analysis of the infrared characteristics of target basis, Algorithm firstly extracted target gray and edge character and Proposed to guide the above two characteristics by the moving of the target information thus we can get new sports guide grayscale characteristics and motion guide border feature. Then proposes a new adaptive fusion mechanism, used these two new information adaptive to integrate into the Mean Shift tracking framework. Finally we designed a kind of automatic target model updating strategy to further improve tracking performance. Experimental results show that this algorithm can compensate shortcoming of the particle filter has too much computation, and can effectively overcome the fault that mean shift is easy to fall into local extreme value instead of global maximum value .Last because of the gray and fusion target motion information, this approach also inhibit interference from the background, ultimately improve the stability and the real-time of the target track.

Tracking Detectors in the STAR Experiment at RHIC

NASA Astrophysics Data System (ADS)

Wieman, Howard

2015-04-01

The STAR experiment at RHIC is designed to measure and identify the thousands of particles produced in 200 Gev/nucleon Au on Au collisions. This talk will focus on the design and construction of two of the main tracking detectors in the experiment, the TPC and the Heavy Flavor Tracker (HFT) pixel detector. The TPC is a solenoidal gas filled detector 4 meters in diameter and 4.2 meters long. It provides precise, continuous tracking and rate of energy loss in the gas (dE/dx) for particles at + - 1 units of pseudo rapidity. The tracking in a half Tesla magnetic field measures momentum and dE/dX provides particle ID. To detect short lived particles tracking close to the point of interaction is required. The HFT pixel detector is a two-layered, high resolution vertex detector located at a few centimeters radius from the collision point. It determines origins of the tracks to a few tens of microns for the purpose of extracting displaced vertices, allowing the identification of D mesons and other short-lived particles. The HFT pixel detector uses detector chips developed by the IPHC group at Strasbourg that are based on standard IC Complementary Metal-Oxide-Semiconductor (CMOS) technology. This is the first time that CMOS pixel chips have been incorporated in a collider application.

Tilted light sheet microscopy with 3D point spread functions for single-molecule super-resolution imaging in mammalian cells

NASA Astrophysics Data System (ADS)

Gustavsson, Anna-Karin; Petrov, Petar N.; Lee, Maurice Y.; Shechtman, Yoav; Moerner, W. E.

2018-02-01

To obtain a complete picture of subcellular nanostructures, cells must be imaged with high resolution in all three dimensions (3D). Here, we present tilted light sheet microscopy with 3D point spread functions (TILT3D), an imaging platform that combines a novel, tilted light sheet illumination strategy with engineered long axial range point spread functions (PSFs) for low-background, 3D super localization of single molecules as well as 3D super-resolution imaging in thick cells. TILT3D is built upon a standard inverted microscope and has minimal custom parts. The axial positions of the single molecules are encoded in the shape of the PSF rather than in the position or thickness of the light sheet, and the light sheet can therefore be formed using simple optics. The result is flexible and user-friendly 3D super-resolution imaging with tens of nm localization precision throughout thick mammalian cells. We validated TILT3D for 3D superresolution imaging in mammalian cells by imaging mitochondria and the full nuclear lamina using the double-helix PSF for single-molecule detection and the recently developed Tetrapod PSF for fiducial bead tracking and live axial drift correction. We envision TILT3D to become an important tool not only for 3D super-resolution imaging, but also for live whole-cell single-particle and single-molecule tracking.

Visualisation of γH2AX Foci Caused by Heavy Ion Particle Traversal; Distinction between Core Track versus Non-Track Damage

PubMed Central

Nakajima, Nakako Izumi; Brunton, Holly; Watanabe, Ritsuko; Shrikhande, Amruta; Hirayama, Ryoichi; Matsufuji, Naruhiro; Fujimori, Akira; Murakami, Takeshi; Okayasu, Ryuichi; Jeggo, Penny; Shibata, Atsushi

2013-01-01

Heavy particle irradiation produces complex DNA double strand breaks (DSBs) which can arise from primary ionisation events within the particle trajectory. Additionally, secondary electrons, termed delta-electrons, which have a range of distributions can create low linear energy transfer (LET) damage within but also distant from the track. DNA damage by delta-electrons distant from the track has not previously been carefully characterised. Using imaging with deconvolution, we show that at 8 hours after exposure to Fe (∼200 keV/µm) ions, γH2AX foci forming at DSBs within the particle track are large and encompass multiple smaller and closely localised foci, which we designate as clustered γH2AX foci. These foci are repaired with slow kinetics by DNA non-homologous end-joining (NHEJ) in G1 phase with the magnitude of complexity diminishing with time. These clustered foci (containing 10 or more individual foci) represent a signature of DSBs caused by high LET heavy particle radiation. We also identified simple γH2AX foci distant from the track, which resemble those arising after X-ray exposure, which we attribute to low LET delta-electron induced DSBs. They are rapidly repaired by NHEJ. Clustered γH2AX foci induced by heavy particle radiation cause prolonged checkpoint arrest compared to simple γH2AX foci following X-irradiation. However, mitotic entry was observed when ∼10 clustered foci remain. Thus, cells can progress into mitosis with multiple clusters of DSBs following the traversal of a heavy particle. PMID:23967070

Luminescent Sensors for Tracking Spatial Particle Distribution in an Explosion

NASA Astrophysics Data System (ADS)

Eilers, Hergen; Gunawidjaja, Ray; Diez-Y-Riega, Helena; Svingala, Forrest; Daniels, Amber; Lightstone, James; Washington State University Collaboration; Nswc Iheodtd Collaboration

2015-06-01

We previously developed and tested thermally sensitive particles that, when seeded into an explosive event, flow with the expanding post-detonation fireball and provide ex-situ measurements of this thermal environment. This current work presents the development and testing of tracking particles that are used in concert with the thermally sensitive particles to encode the initial positions of materials recovered for ex-situ analysis. These tracking sensors consist of fully-crystallized (c) rare-earth-doped yttria particles such as c-Dy:Y2O3, c-Sm:Y2O3, and c-Er,Yb:Y2O3. The temperature sensors consist of mixtures of precursor (p) and fully crystallized materials such as p-Eu:Y2O3/c-Tb:Y2O3 orp-Eu:ZrO2/c-Tb:Y2O3. Three mixtures containing one of the tracking sensors and one of the temperature sensing mixtures are placed at different locations within the chamber. Post-detonation, the tracking particles in the debris are excited by 365 nm light, resulting in different color luminescence, and allowing for potential visual inspection of the particle distribution originating from the different locations. Meanwhile, the temperature is determined from spectral changes of the precursor sensor materials or by comparison of the precursor sensor materials with the Tb:Y2O3 intensity reference. Defense Threat Reduction Agency, HDTRA1-10-1-0005.

Magnetomicrofluidics Circuits for Organizing Bioparticle Arrays

NASA Astrophysics Data System (ADS)

Abedini-Nassab, Roozbeh

Single-cell analysis (SCA) tools have important applications in the analysis of phenotypic heterogeneity, which is difficult or impossible to analyze in bulk cell culture or patient samples. SCA tools thus have a myriad of applications ranging from better credentialing of drug therapies to the analysis of rare latent cells harboring HIV infection or in Cancer. However, existing SCA systems usually lack the required combination of programmability, flexibility, and scalability necessary to enable the study of cell behaviors and cell-cell interactions at the scales sufficient to analyze extremely rare events. To advance the field, I have developed a novel, programmable, and massively-parallel SCA tool which is based on the principles of computer circuits. By integrating these magnetic circuits with microfluidics channels, I developed a platform that can organize a large number of single particles into an array in a controlled manner. My magnetophoretic circuits use passive elements constructed in patterned magnetic thin films to move cells along programmed tracks with an external rotating magnetic field. Cell motion along these tracks is analogous to the motion of charges in an electrical conductor, following a rule similar to Ohm's law. I have also developed asymmetric conductors, similar to electrical diodes, and storage sites for cells that behave similarly to electrical capacitors. I have also developed magnetophoretic circuits which use an overlaid pattern of microwires to switch single cells between different tracks. This switching mechanism, analogous to the operation of electronic transistors, is achieved by establishing a semiconducting gap in the magnetic pattern which can be changed from an insulating state to a conducting state by application of electrical current to an overlaid electrode. I performed an extensive study on the operation of transistors to optimize their geometry and minimize the required gate currents. By combining these elements into integrated circuits, I have built devices which are capable of organizing a precise number of cells into individually addressable array sites, similar to how a random access memory (RAM) stores electronic data. My programmable magnetic circuits allow for the organization of both cells and single-cell pairs into large arrays. Single cells can also potentially be retrieved for downstream high-throughput genomic analysis. In order to enhance the efficiency of the tool and to increase the delivery speed of the particles, I have also developed microfluidics systems that are combined with the magnetophoretic circuits. This hybrid system, called magnetomicrofluidics, is capable of rapidly organizing an array of particles and cells with the high precision and control. I have also shown that cells can be grown inside these chips for multiple days, enabling the long-term phenotypic analysis of rare cellular events. These types of studies can reveal important insights about the intercellular signaling networks and answer crucial questions in biology and immunology.

Tracking single Kv2.1 channels in live cells reveals anomalous subdiffusion and ergodicity breaking

NASA Astrophysics Data System (ADS)

Weigel, Aubrey; Simon, Blair; Tamkun, Michael; Krapf, Diego

2011-03-01

The dynamic organization of the plasma membrane is responsible for essential cellular processes, such as receptor trafficking and signaling. By studying the dynamics of transmembrane proteins a greater understanding of these processes as a whole can be achieved. It is broadly observed that the diffusion pattern of membrane protein displays anomalous subdiffusion. However, the mechanisms responsible for this behavior are not yet established. We explore the dynamics of the voltage gated potassium channel Kv2.1 by using single-particle tracking. We analyze Kv2.1 channel trajectories in terms of the time and ensemble distributions of square displacements. Our results reveal that all Kv2.1 channels experience anomalous subdiffusion and we observe that the Kv2.1 diffusion pattern is non-ergodic. We further investigated the role of the actin cytoskeleton in these channel dynamics by applying actin depolymerizing drugs. It is seen that with the breakdown of the actin cytoskeleton the Kv2.1 channel trajectories recover ergodicity.

Dynamics of different-sized solid-state nanocrystals as tracers for a drug-delivery system in the interstitium of a human tumor xenograft

PubMed Central

Kawai, Masaaki; Higuchi, Hideo; Takeda, Motohiro; Kobayashi, Yoshio; Ohuchi, Noriaki

2009-01-01

Introduction Recent anticancer drugs have been made larger to pass selectively through tumor vessels and stay in the interstitium. Understanding drug movement in association with its size at the single-molecule level and estimating the time needed to reach the targeted organ is indispensable for optimizing drug delivery because single cell-targeted therapy is the ongoing paradigm. This report describes the tracking of single solid nanoparticles in tumor xenografts and the estimation of arrival time. Methods Different-sized nanoparticles measuring 20, 40, and 100 nm were injected into the tail vein of the female Balb/c nu/nu mice bearing human breast cancer on their backs. The movements of the nanoparticles were visualized through the dorsal skin-fold chamber with the high-speed confocal microscopy that we manufactured. Results An analysis of the particle trajectories revealed diffusion to be inversely related to the particle size and position in the tumor, whereas the velocity of the directed movement was related to the position. The difference in the velocity was the greatest for 40-nm particles in the perivascular to the intercellular region: difference = 5.8 nm/s. The arrival time of individual nanoparticles at tumor cells was simulated. The estimated times for the 20-, 40-, and 100-nm particles to reach the tumor cells were 158.0, 218.5, and 389.4 minutes, respectively, after extravasation. Conclusions This result suggests that the particle size can be individually designed for each goal. These data and methods are also important for understanding drug pharmacokinetics. Although this method may be subject to interference by surface molecules attached on the particles, it has the potential to elucidate the pharmacokinetics involved in constructing novel drug-delivery systems involving cell-targeted therapy. PMID:19575785

Split ring resonator based THz-driven electron streak camera featuring femtosecond resolution

PubMed Central

Fabiańska, Justyna; Kassier, Günther; Feurer, Thomas

2014-01-01

Through combined three-dimensional electromagnetic and particle tracking simulations we demonstrate a THz driven electron streak camera featuring a temporal resolution on the order of a femtosecond. The ultrafast streaking field is generated in a resonant THz sub-wavelength antenna which is illuminated by an intense single-cycle THz pulse. Since electron bunches and THz pulses are generated with parts of the same laser system, synchronization between the two is inherently guaranteed. PMID:25010060

Cytosolic delivery of materials with endosome-disrupting colloids

DOEpatents

Helms, Brett A.; Bayles, Andrea R.

2016-03-15

A facile procedure to deliver nanocrystals to the cytosol of live cells that is both rapid and general. The technique employs a unique cationic core-shell polymer colloid that directs nanocrystals to the cytosol of living cells within a few hours of incubation. The present methods and compositions enable a host of advanced applications arising from efficient cytosolic delivery of nanocrystal imaging probes: from single particle tracking experiments to monitoring protein-protein interactions in live cells for extended periods.

Automated Proton Track Identification in MicroBooNE Using Gradient Boosted Decision Trees

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

Woodruff, Katherine

MicroBooNE is a liquid argon time projection chamber (LArTPC) neutrino experiment that is currently running in the Booster Neutrino Beam at Fermilab. LArTPC technology allows for high-resolution, three-dimensional representations of neutrino interactions. A wide variety of software tools for automated reconstruction and selection of particle tracks in LArTPCs are actively being developed. Short, isolated proton tracks, the signal for low- momentum-transfer neutral current (NC) elastic events, are easily hidden in a large cosmic background. Detecting these low-energy tracks will allow us to probe interesting regions of the proton's spin structure. An effective method for selecting NC elastic events is tomore » combine a highly efficient track reconstruction algorithm to find all candidate tracks with highly accurate particle identification using a machine learning algorithm. We present our work on particle track classification using gradient tree boosting software (XGBoost) and the performance on simulated neutrino data.« less

Intracellular dynamics and fate of polystyrene nanoparticles in A549 Lung epithelial cells monitored by image (cross-) correlation spectroscopy and single particle tracking.

PubMed

Deville, Sarah; Penjweini, Rozhin; Smisdom, Nick; Notelaers, Kristof; Nelissen, Inge; Hooyberghs, Jef; Ameloot, Marcel

2015-10-01

Novel insights in nanoparticle (NP) uptake routes of cells, their intracellular trafficking and subcellular targeting can be obtained through the investigation of their temporal and spatial behavior. In this work, we present the application of image (cross-) correlation spectroscopy (IC(C)S) and single particle tracking (SPT) to monitor the intracellular dynamics of polystyrene (PS) NPs in the human lung carcinoma A549 cell line. The ensemble kinetic behavior of NPs inside the cell was characterized by temporal and spatiotemporal image correlation spectroscopy (TICS and STICS). Moreover, a more direct interpretation of the diffusion and flow detected in the NP motion was obtained by SPT by monitoring individual NPs. Both techniques demonstrate that the PS NP transport in A549 cells is mainly dependent on microtubule-assisted transport. By applying spatiotemporal image cross-correlation spectroscopy (STICCS), the correlated motions of NPs with the early endosomes, late endosomes and lysosomes are identified. PS NPs were equally distributed among the endolysosomal compartment during the time interval of the experiments. The cotransport of the NPs with the lysosomes is significantly larger compared to the other cell organelles. In the present study we show that the complementarity of ICS-based techniques and SPT enables a consistent elaborate model of the complex behavior of NPs inside biological systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Strange Particle Reconstruction by the Missing Mass Method

NASA Astrophysics Data System (ADS)

Kisel, Pavel; Kisel, Ivan; Senger, Peter; Vassiliev, Iouri; Zyzak, Maksym

2018-02-01

The main goal of modern heavy-ion experiments is a comprehensive study of the QCD phase diagram, in a region of Quark-Gluon Plasma (QGP) and possible phase transition to QGP phase. Strange particles produced in the collision are sensitive probes of the created media. Reconstruction of Σ particles together with other strange particles completes the picture of strangeness production. Σ+ and Σ- have all decay modes with at least one neutral daughter, which can not be registered by the CBM detector. For their identification the missing mass method is proposed: a) tracks of the mother (Σ-) and the charged daughter (π-) particles are reconstructed in the tracking system; b) the neutral daughter particle (n) is reconstructed from these tracks; c) a mass constraint is set on the reconstructed neutral daughter; d) the mother particle is constructed of the charged and reconstructed neutral daughter particles and the mass spectrum is obtained, by which the particle can be identified. The method can be applied for other strange particles too. In total 18 particle decays with neutral daughter are now included into physics analysis.

Constrained diffusion or immobile fraction on cell surfaces: a new interpretation.

PubMed Central

Feder, T J; Brust-Mascher, I; Slattery, J P; Baird, B; Webb, W W

1996-01-01

Protein lateral mobility in cell membranes is generally measured using fluorescence photobleaching recovery (FPR). Since the development of this technique, the data have been interpreted by assuming free Brownian diffusion of cell surface receptors in two dimensions, an interpretation that requires that a subset of the diffusing species remains immobile. The origin of this so-called immobile fraction remains a mystery. In FPR, the motions of thousands of particles are inherently averaged, inevitably masking the details of individual motions. Recently, tracking of individual cell surface receptors has identified several distinct types of motion (Gross and Webb, 1988; Ghosh and Webb, 1988, 1990, 1994; Kusumi et al. 1993; Qian et al. 1991; Slattery, 1995), thereby calling into question the classical interpretation of FPR data as free Brownian motion of a limited mobile fraction. We have measured the motion of fluorescently labeled immunoglobulin E complexed to high affinity receptors (Fc epsilon RI) on rat basophilic leukemia cells using both single particle tracking and FPR. As in previous studies, our tracking results show that individual receptors may diffuse freely, or may exhibit restricted, time-dependent (anomalous) diffusion. Accordingly, we have analyzed FPR data by a new model to take this varied motion into account, and we show that the immobile fraction may be due to particles moving with the anomalous subdiffusion associated with restricted lateral mobility. Anomalous subdiffusion denotes random molecular motion in which the mean square displacements grow as a power law in time with a fractional positive exponent less than one. These findings call for a new model of cell membrane structure. PMID:8744314

Lagrangian Particle Tracking Simulation for Warm-Rain Processes in Quasi-One-Dimensional Domain

NASA Astrophysics Data System (ADS)

Kunishima, Y.; Onishi, R.

2017-12-01

Conventional cloud simulations are based on the Euler method and compute each microphysics process in a stochastic way assuming infinite numbers of particles within each numerical grid. They therefore cannot provide the Lagrangian statistics of individual particles in cloud microphysics (i.e., aerosol particles, cloud particles, and rain drops) nor discuss the statistical fluctuations due to finite number of particles. We here simulate the entire precipitation process of warm-rain, with tracking individual particles. We use the Lagrangian Cloud Simulator (LCS), which is based on the Euler-Lagrangian framework. In that framework, flow motion and scalar transportation are computed with the Euler method, and particle motion with the Lagrangian one. The LCS tracks particle motions and collision events individually with considering the hydrodynamic interaction between approaching particles with a superposition method, that is, it can directly represent the collisional growth of cloud particles. It is essential for trustworthy collision detection to take account of the hydrodynamic interaction. In this study, we newly developed a stochastic model based on the Twomey cloud condensation nuclei (CCN) activation for the Lagrangian tracking simulation and integrated it into the LCS. Coupling with the Euler computation for water vapour and temperature fields, the initiation and condensational growth of water droplets were computed in the Lagrangian way. We applied the integrated LCS for a kinematic simulation of warm-rain processes in a vertically-elongated domain of, at largest, 0.03×0.03×3000 (m3) with horizontal periodicity. Aerosol particles with a realistic number density, 5×107 (m3), were evenly distributed over the domain at the initial state. Prescribed updraft at the early stage initiated development of a precipitating cloud. We have confirmed that the obtained bulk statistics fairly agree with those from a conventional spectral-bin scheme for a vertical column domain. The centre of the discussion will be the Lagrangian statistics which is collected from the individual behaviour of the tracked particles.

A New Approach to Time-Resolved 3D-PTV

NASA Astrophysics Data System (ADS)

Boomsma, Aaron; Troolin, Dan; Bjorkquist, Dan; TSI Inc Team

2017-11-01

Volumetric three-component velocimetry via particle tracking is a powerful alternative to TomoPIV. It has been thoroughly documented that compared to TomoPIV, particle tracking velocimetry (PTV) methods (whether 2D or 3D) better resolve regions of high velocity gradient, identify fewer ghost particles, and are less computationally demanding, which results in shorter processing times. Recently, 3D-PTV has seen renewed interest in the PIV community with the availability of time-resolved data. Of course, advances in hardware are partly to thank for that availability-higher speed cameras, more effective memory management, and higher speed lasers. But in software, algorithms that utilize time resolved data to improve 3D particle reconstruction and particle tracking are also under development and advancing (e.g. shake-the-box, neighbor tracking reconstruction, etc.). .In the current study, we present a new 3D-PTV method that incorporates time-resolved data. We detail the method, its performance in terms of particle identification and reconstruction error and their relation to varying seeding densities, as well as computational performance.

Color Feature-Based Object Tracking through Particle Swarm Optimization with Improved Inertia Weight

PubMed Central

Guo, Siqiu; Zhang, Tao; Song, Yulong

2018-01-01

This paper presents a particle swarm tracking algorithm with improved inertia weight based on color features. The weighted color histogram is used as the target feature to reduce the contribution of target edge pixels in the target feature, which makes the algorithm insensitive to the target non-rigid deformation, scale variation, and rotation. Meanwhile, the influence of partial obstruction on the description of target features is reduced. The particle swarm optimization algorithm can complete the multi-peak search, which can cope well with the object occlusion tracking problem. This means that the target is located precisely where the similarity function appears multi-peak. When the particle swarm optimization algorithm is applied to the object tracking, the inertia weight adjustment mechanism has some limitations. This paper presents an improved method. The concept of particle maturity is introduced to improve the inertia weight adjustment mechanism, which could adjust the inertia weight in time according to the different states of each particle in each generation. Experimental results show that our algorithm achieves state-of-the-art performance in a wide range of scenarios. PMID:29690610

Color Feature-Based Object Tracking through Particle Swarm Optimization with Improved Inertia Weight.

PubMed

Guo, Siqiu; Zhang, Tao; Song, Yulong; Qian, Feng

2018-04-23

This paper presents a particle swarm tracking algorithm with improved inertia weight based on color features. The weighted color histogram is used as the target feature to reduce the contribution of target edge pixels in the target feature, which makes the algorithm insensitive to the target non-rigid deformation, scale variation, and rotation. Meanwhile, the influence of partial obstruction on the description of target features is reduced. The particle swarm optimization algorithm can complete the multi-peak search, which can cope well with the object occlusion tracking problem. This means that the target is located precisely where the similarity function appears multi-peak. When the particle swarm optimization algorithm is applied to the object tracking, the inertia weight adjustment mechanism has some limitations. This paper presents an improved method. The concept of particle maturity is introduced to improve the inertia weight adjustment mechanism, which could adjust the inertia weight in time according to the different states of each particle in each generation. Experimental results show that our algorithm achieves state-of-the-art performance in a wide range of scenarios.

3D imaging of neutron tracks using confocal microscopy

NASA Astrophysics Data System (ADS)

Gillmore, Gavin; Wertheim, David; Flowers, Alan

2016-04-01

Neutron detection and neutron flux assessment are important aspects in monitoring nuclear energy production. Neutron flux measurements can also provide information on potential biological damage from exposure. In addition to the applications for neutron measurement in nuclear energy, neutron detection has been proposed as a method of enhancing neutrino detectors and cosmic ray flux has also been assessed using ground-level neutron detectors. Solid State Nuclear Track Detectors (or SSNTDs) have been used extensively to examine cosmic rays, long-lived radioactive elements, radon concentrations in buildings and the age of geological samples. Passive SSNTDs consisting of a CR-39 plastic are commonly used to measure radon because they respond to incident charged particles such as alpha particles from radon gas in air. They have a large dynamic range and a linear flux response. We have previously applied confocal microscopy to obtain 3D images of alpha particle tracks in SSNTDs from radon track monitoring (1). As a charged particle traverses through the polymer it creates an ionisation trail along its path. The trail or track is normally enhanced by chemical etching to better expose radiation damage, as the damaged area is more sensitive to the etchant than the bulk material. Particle tracks in CR-39 are usually assessed using 2D optical microscopy. In this study 6 detectors were examined using an Olympus OLS4100 LEXT 3D laser scanning confocal microscope (Olympus Corporation, Japan). The detectors had been etched for 2 hours 50 minutes at 85 °C in 6.25M NaOH. Post etch the plastics had been treated with a 10 minute immersion in a 2% acetic acid stop bath, followed by rinsing in deionised water. The detectors examined had been irradiated with a 2mSv neutron dose from an Am(Be) neutron source (producing roughly 20 tracks per mm2). We were able to successfully acquire 3D images of neutron tracks in the detectors studied. The range of track diameter observed was between 4 and 10 microns. Thus this study suggests that, using confocal microscopy, 3D imaging of neutron tracks in SSNTDs is feasible. (1) Wertheim D, Gillmore G, Brown L, Petford N. A new method of imaging particle tracks in solid state nuclear track detectors. J Microsc. 2010; 237: 1-6.

Image-based Lagrangian Particle Tracking in Bed-load Experiments.

PubMed

Radice, Alessio; Sarkar, Sankar; Ballio, Francesco

2017-07-20

Image analysis has been increasingly used for the measurement of river flows due to its capabilities to furnish detailed quantitative depictions at a relatively low cost. This manuscript describes an application of particle tracking velocimetry (PTV) to a bed-load experiment with lightweight sediment. The key characteristics of the investigated sediment transport conditions were the presence of a covered flow and of a fixed rough bed above which particles were released in limited number at the flume inlet. Under the applied flow conditions, the motion of the individual bed-load particles was intermittent, with alternating movement and stillness terms. The flow pattern was preliminarily characterized by acoustic measurements of vertical profiles of the stream-wise velocity. During process visualization, a large field of view was obtained using two action-cameras placed at different locations along the flume. The experimental protocol is described in terms of channel calibration, experiment realization, image pre-processing, automatic particle tracking, and post-processing of particle track data from the two cameras. The presented proof-of-concept results include probability distributions of the particle hop length and duration. The achievements of this work are compared to those of existing literature to demonstrate the validity of the protocol.

Minimum requirements for predictive pore-network modeling of solute transport in micromodels

NASA Astrophysics Data System (ADS)

Mehmani, Yashar; Tchelepi, Hamdi A.

2017-10-01

Pore-scale models are now an integral part of analyzing fluid dynamics in porous materials (e.g., rocks, soils, fuel cells). Pore network models (PNM) are particularly attractive due to their computational efficiency. However, quantitative predictions with PNM have not always been successful. We focus on single-phase transport of a passive tracer under advection-dominated regimes and compare PNM with high-fidelity direct numerical simulations (DNS) for a range of micromodel heterogeneities. We identify the minimum requirements for predictive PNM of transport. They are: (a) flow-based network extraction, i.e., discretizing the pore space based on the underlying velocity field, (b) a Lagrangian (particle tracking) simulation framework, and (c) accurate transfer of particles from one pore throat to the next. We develop novel network extraction and particle tracking PNM methods that meet these requirements. Moreover, we show that certain established PNM practices in the literature can result in first-order errors in modeling advection-dominated transport. They include: all Eulerian PNMs, networks extracted based on geometric metrics only, and flux-based nodal transfer probabilities. Preliminary results for a 3D sphere pack are also presented. The simulation inputs for this work are made public to serve as a benchmark for the research community.

Engineering cell-fluorescent ion track hybrid detectors

PubMed Central

2013-01-01

Background The lack of sensitive biocompatible particle track detectors has so far limited parallel detection of physical energy deposition and biological response. Fluorescent nuclear track detectors (FNTDs) based on Al2O3:C,Mg single crystals combined with confocal laser scanning microscopy (CLSM) provide 3D information on ion tracks with a resolution limited by light diffraction. Here we report the development of next generation cell-fluorescent ion track hybrid detectors (Cell-Fit-HD). Methods The biocompatibility of FNTDs was tested using six different cell lines, i.e. human non-small cell lung carcinoma (A549), glioblastoma (U87), androgen independent prostate cancer (PC3), epidermoid cancer (A431) and murine (VmDk) glioma SMA-560. To evaluate cell adherence, viability and conformal coverage of the crystals different seeding densities and alternative coating with extracellular matrix (fibronectin) was tested. Carbon irradiation was performed in Bragg peak (initial 270.55 MeV u−1). A series of cell compartment specific fluorescence stains including nuclear (HOECHST), membrane (Glut-1), cytoplasm (Calcein AM, CM-DiI) were tested on Cell-Fit-HDs and a single CLSM was employed to co-detect the physical (crystal) as well as the biological (cell layer) information. Results The FNTD provides a biocompatible surface. Among the cells tested, A549 cells formed the most uniform, viable, tightly packed epithelial like monolayer. The ion track information was not compromised in Cell-Fit-HD as compared to the FNTD alone. Neither cell coating and culturing, nor additional staining procedures affected the properties of the FNTD surface to detect ion tracks. Standard immunofluorescence and live staining procedures could be employed to co-register cell biology and ion track information. Conclusions The Cell-Fit-Hybrid Detector system is a promising platform for a multitude of studies linking biological response to energy deposition at high level of optical microscopy resolution. PMID:23758749

Optimize Operating Conditions on Fine Particle Grinding Process with Vertically Stirred Media Mill

NASA Astrophysics Data System (ADS)

Yang, Yang; Rowson, Neil; Ingram, Andy

2016-11-01

Stirred media mill recently is commonly utilized among mining process due to its high stressing intensity and efficiency. However, the relationship between size reduction and flow pattern within the mixing pot is still not fully understand. Thus, this work investigates fine particle grinding process within vertically stirred media mills by altering stirrer geometry, tip speed and solids loading. Positron Emitting Particle Tracking (PEPT) technology is utilized to plot routine of particles velocity map. By tacking trajectory of a single particle movement within the mixing vessel, the overall flow pattern is possible to be plotted. Ground calcium carbonate, a main product of Imerys, is chosen as feeding material (feed size D80 30um) mixed with water to form high viscous suspension. To obtain fine size product (normally D80 approximately 2um), large amount of energy is drawn by grinding mill to break particles through impact, shear attrition or compression or a combination of them. The results indicate higher energy efficient is obtained with more dilute suspension. The optimized stirrer proves more energy-saving performance by altering the slurry circulate. Imerys Minerals Limited.

The Sun Radio Imaging Space Experiment (SunRISE) Mission

NASA Astrophysics Data System (ADS)

Lazio, Joseph; Kasper, Justin; Maksimovic, Milan; Alibay, Farah; Amiri, Nikta; Bastian, Tim; Cohen, Christina; Landi, Enrico; Manchester, Ward; Reinard, Alysha; Schwadron, Nathan; Cecconi, Baptiste; Hallinan, Gregg; Hegedus, Alex; Krupar, Vratislav; Zaslavsky, Arnaud

2017-04-01

Radio emission from coronal mass ejections (CMEs) is a direct tracer of particle acceleration in the inner heliosphere and potential magnetic connections from the lower solar corona to the larger heliosphere. Energized electrons excite Langmuir waves, which then convert into intense radio emission at the local plasma frequency, with the most intense acceleration thought to occur within 20 RS. The radio emission from CMEs is quite strong such that only a relatively small number of antennas is required to detect and map it, but many aspects of this particle acceleration and transport remain poorly constrained. Ground-based arrays would be quite capable of tracking the radio emission associated with CMEs, but absorption by the Earth's ionosphere limits the frequency coverage of ground-based arrays (ν ≳ 15 MHz), which in turn limits the range of solar distances over which they can track the radio emission (≲ 3RS). The state-of-the-art for tracking such emission from space is defined by single antennas (Wind/WAVES, Stereo/SWAVES), in which the tracking is accomplished by assuming a frequency-to-density mapping; there has been some success in triangulating the emission between the spacecraft, but considerable uncertainties remain. We describe the Sun Radio Imaging Space Experiment (SunRISE) mission concept: A constellation of small spacecraft in a geostationary graveyard orbit designed to localize and track radio emissions in the inner heliosphere. Each spacecraft would carry a receiving system for observations below 25 MHz, and SunRISE would produce the first images of CMEs more than a few solar radii from the Sun. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

The Sun Radio Imaging Space Experiment (SunRISE) Mission

NASA Astrophysics Data System (ADS)

Kasper, J. C.; Lazio, J.; Alibay, F.; Amiri, N.; Bastian, T.; Cohen, C.; Landi, E.; Hegedus, A. M.; Maksimovic, M.; Manchester, W.; Reinard, A.; Schwadron, N.; Cecconi, B.; Hallinan, G.; Krupar, V.

2017-12-01

Radio emission from coronal mass ejections (CMEs) is a direct tracer of particle acceleration in the inner heliosphere and potential magnetic connections from the lower solar corona to the larger heliosphere. Energized electrons excite Langmuir waves, which then convert into intense radio emission at the local plasma frequency, with the most intense acceleration thought to occur within 20 R_S. The radio emission from CMEs is quite strong such that only a relatively small number of antennas is required to detect and map it, but many aspects of this particle acceleration and transport remain poorly constrained. Ground-based arrays would be quite capable of tracking the radio emission associated with CMEs, but absorption by the Earth's ionosphere limits the frequency coverage of ground-based arrays (nu > 15 MHz), which in turn limits the range of solar distances over which they can track the radio emission (< 3 R_S). The state-of-the-art for tracking such emission from space is defined by single antennas (Wind/WAVES, Stereo/SWAVES), in which the tracking is accomplished by assuming a frequency-to-density mapping; there has been some success in triangulating the emission between the spacecraft, but considerable uncertainties remain. We describe the Sun Radio Imaging Space Experiment (SunRISE) mission concept: A constellation of small spacecraft in a geostationary graveyard orbit designed to localize and track radio emissions in the inner heliosphere. Each spacecraft would carry a receiving system for observations below 25 MHz, and SunRISE would produce the first images of CMEs more than a few solar radii from the Sun. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Particle Tracking Facilitates Real Time Capable Motion Correction in 2D or 3D Two-Photon Imaging of Neuronal Activity.

PubMed

Aghayee, Samira; Winkowski, Daniel E; Bowen, Zachary; Marshall, Erin E; Harrington, Matt J; Kanold, Patrick O; Losert, Wolfgang

2017-01-01

The application of 2-photon laser scanning microscopy (TPLSM) techniques to measure the dynamics of cellular calcium signals in populations of neurons is an extremely powerful technique for characterizing neural activity within the central nervous system. The use of TPLSM on awake and behaving subjects promises new insights into how neural circuit elements cooperatively interact to form sensory perceptions and generate behavior. A major challenge in imaging such preparations is unavoidable animal and tissue movement, which leads to shifts in the imaging location (jitter). The presence of image motion can lead to artifacts, especially since quantification of TPLSM images involves analysis of fluctuations in fluorescence intensities for each neuron, determined from small regions of interest (ROIs). Here, we validate a new motion correction approach to compensate for motion of TPLSM images in the superficial layers of auditory cortex of awake mice. We use a nominally uniform fluorescent signal as a secondary signal to complement the dynamic signals from genetically encoded calcium indicators. We tested motion correction for single plane time lapse imaging as well as multiplane (i.e., volume) time lapse imaging of cortical tissue. Our procedure of motion correction relies on locating the brightest neurons and tracking their positions over time using established techniques of particle finding and tracking. We show that our tracking based approach provides subpixel resolution without compromising speed. Unlike most established methods, our algorithm also captures deformations of the field of view and thus can compensate e.g., for rotations. Object tracking based motion correction thus offers an alternative approach for motion correction, one that is well suited for real time spike inference analysis and feedback control, and for correcting for tissue distortions.

Particle Tracking Facilitates Real Time Capable Motion Correction in 2D or 3D Two-Photon Imaging of Neuronal Activity

PubMed Central

Aghayee, Samira; Winkowski, Daniel E.; Bowen, Zachary; Marshall, Erin E.; Harrington, Matt J.; Kanold, Patrick O.; Losert, Wolfgang

2017-01-01

The application of 2-photon laser scanning microscopy (TPLSM) techniques to measure the dynamics of cellular calcium signals in populations of neurons is an extremely powerful technique for characterizing neural activity within the central nervous system. The use of TPLSM on awake and behaving subjects promises new insights into how neural circuit elements cooperatively interact to form sensory perceptions and generate behavior. A major challenge in imaging such preparations is unavoidable animal and tissue movement, which leads to shifts in the imaging location (jitter). The presence of image motion can lead to artifacts, especially since quantification of TPLSM images involves analysis of fluctuations in fluorescence intensities for each neuron, determined from small regions of interest (ROIs). Here, we validate a new motion correction approach to compensate for motion of TPLSM images in the superficial layers of auditory cortex of awake mice. We use a nominally uniform fluorescent signal as a secondary signal to complement the dynamic signals from genetically encoded calcium indicators. We tested motion correction for single plane time lapse imaging as well as multiplane (i.e., volume) time lapse imaging of cortical tissue. Our procedure of motion correction relies on locating the brightest neurons and tracking their positions over time using established techniques of particle finding and tracking. We show that our tracking based approach provides subpixel resolution without compromising speed. Unlike most established methods, our algorithm also captures deformations of the field of view and thus can compensate e.g., for rotations. Object tracking based motion correction thus offers an alternative approach for motion correction, one that is well suited for real time spike inference analysis and feedback control, and for correcting for tissue distortions. PMID:28860973

Computer program TRACK_TEST for calculating parameters and plotting profiles for etch pits in nuclear track materials

NASA Astrophysics Data System (ADS)

Nikezic, D.; Yu, K. N.

2006-01-01

A computer program called TRACK_TEST for calculating parameters (lengths of the major and minor axes) and plotting profiles in nuclear track materials resulted from light-ion irradiation and subsequent chemical etching is described. The programming steps are outlined, including calculations of alpha-particle ranges, determination of the distance along the particle trajectory penetrated by the chemical etchant, calculations of track coordinates, determination of the lengths of the major and minor axes and determination of the contour of the track opening. Descriptions of the program are given, including the built-in V functions for the two commonly employed nuclear track materials commercially known as LR 115 (cellulose nitrate) and CR-39 (poly allyl diglycol carbonate) irradiated by alpha particles. Program summaryTitle of the program:TRACK_TEST Catalogue identifier:ADWT Program obtainable from:CPC Program Library, Queen's University of Belfast, N. Ireland Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWT Computer:Pentium PC Operating systems:Windows 95+ Programming language:Fortran 90 Memory required to execute with typical data:256 MB No. of lines in distributed program, including test data, etc.: 2739 No. of bytes in distributed program, including test data, etc.:204 526 Distribution format:tar.gz External subprograms used:The entire code must be linked with the MSFLIB library Nature of problem: Fast heavy charged particles (like alpha particles and other light ions etc.) create latent tracks in some dielectric materials. After chemical etching in aqueous NaOH or KOH solutions, these tracks become visible under an optical microscope. The growth of a track is based on the simultaneous actions of the etchant on undamaged regions (with the bulk etch rate V) and along the particle track (with the track etch rate V). Growth of the track is described satisfactorily by these two parameters ( V and V). Several models have been presented in the past describing the track development, one of which is the model of Nikezic and Yu (2003) [D. Nikezic, K.N. Yu, Three-dimensional analytical determination of the track parameters. Over-etched tracks, Radiat. Meas. 37 (2003) 39-45] used in the present program. The present computer program has been written to calculate coordinates of points on the track wall and to determine other relevant track parameters. Solution method:Coordinates of points on the track wall assuming normal incidence were calculated by using the method as described by Fromm et al. (1988) [M. Fromm, A. Chambaudet, F. Membrey, Data bank for alpha particle tracks in CR39 with energies ranging from 0.5 to 5 MeV recording for various incident angles, Nucl. Tracks Radiat. Meas. 15 (1988) 115-118]. The track is then rotated through the incident angle in order to obtain the coordinates of the oblique track [D. Nikezic, K.N. Yu, Three-dimensional analytical determination of the track parameters. Over-etched tracks, Radiat. Meas. 37 (2003) 39-45; D. Nikezic, Three dimensional analytical determination of the track parameters, Radiat. Meas. 32 (2000) 277-282]. In this way, the track profile in two dimensions (2D) was obtained. In the next step, points in the track wall profile are rotated around the particle trajectory. In this way, circles that outline the track in three dimensions (3D) are obtained. The intersection between the post-etching surface of the detector and the 3D track is the track opening (or the track contour). Coordinates of the track 2D and 3D profiles and the track opening are saved in separate output data files. Restrictions: The program cannot calculate track parameters for the incident angle of exactly 90°. The alpha-particle energy should be smaller than 10 MeV. Furthermore, the program cannot perform calculations for tracks in some extreme cases, such as for very low incident energies or very small incident angles. Additional comments: This is a freeware, but publications arising from using this program should cite the present paper and the paper describing the track growth model [D. Nikezic, K.N. Yu, Three-dimensional analytical determination of the track parameters. Over-etched tracks, Radiat. Meas. 37 (2003) 39-45]. Moreover, the references for the V functions used should also be cited. For the CR-39 detector: Function (1): S.A. Durrani, R.K. Bull, Solid State Nuclear Track Detection. Principles, Methods and Applications, Pergamon Press, 1987. Function (2): C. Brun, M. Fromm, M. Jouffroy, P. Meyer, J.E. Groetz, F. Abel, A. Chambaudet, B. Dorschel, D. Hermsdorf, R. Bretschneider, K. Kadner, H. Kuhne, Intercomparative study of the detection characteristics of the CR-39 SSNTD for light ions: Present status of the Besancon-Dresden approaches, Radiat. Meas. 31 (1999) 89-98. Function (3): K.N. Yu, F.M.F. Ng, D. Nikezic, Measuring depths of sub-micron tracks in a CR-39 detector from replicas using atomic force microscopy, Radiat. Meas. 40 (2005) 380-383. For the LR 115 detector: Function (1): S.A. Durrani, P.F. Green, The effect of etching conditions on the response of LR 115, Nucl. Tracks 8 (1984) 21-24. Function (2): C.W.Y. Yip, D. Nikezic, J.P.Y Ho, K.N. Yu, Chemical etching characteristics for cellulose nitrate, Mat. Chem. Phys. 95 (2005) 307-312. Running time: Order of several minutes, dependent on input parameters and the resolution requested by the user.

Simulation of radiation effects on three-dimensional computer optical memories

NASA Technical Reports Server (NTRS)

Moscovitch, M.; Emfietzoglou, D.

1997-01-01

A model was developed to simulate the effects of heavy charged-particle (HCP) radiation on the information stored in three-dimensional computer optical memories. The model is based on (i) the HCP track radial dose distribution, (ii) the spatial and temporal distribution of temperature in the track, (iii) the matrix-specific radiation-induced changes that will affect the response, and (iv) the kinetics of transition of photochromic molecules from the colored to the colorless isomeric form (bit flip). It is shown that information stored in a volume of several nanometers radius around the particle's track axis may be lost. The magnitude of the effect is dependent on the particle's track structure.

Gas Electron Multipler (GEM) detectors for parity-violating electron scattering experiments at Jefferson Lab

NASA Astrophysics Data System (ADS)

Matter, John; Gnanvo, Kondo; Liyanage, Nilanga; Solid Collaboration; Moller Collaboration

2017-09-01

The JLab Parity Violation In Deep Inelastic Scattering (PVDIS) experiment will use the upgraded 12 GeV beam and proposed Solenoidal Large Intensity Device (SoLID) to measure the parity-violating electroweak asymmetry in DIS of polarized electrons with high precision in order to search for physics beyond the Standard Model. Unlike many prior Parity-Violating Electron Scattering (PVES) experiments, PVDIS is a single-particle tracking experiment. Furthermore the experiment's high luminosity combined with the SoLID spectrometer's open configuration creates high-background conditions. As such, the PVDIS experiment has the most demanding tracking detector needs of any PVES experiment to date, requiring precision detectors capable of operating at high-rate conditions in PVDIS's full production luminosity. Developments in large-area GEM detector R&D and SoLID simulations have demonstrated that GEMs provide a cost-effective solution for PVDIS's tracking needs. The integrating-detector-based JLab Measurement Of Lepton Lepton Electroweak Reaction (MOLLER) experiment requires high-precision tracking for acceptance calibration. Large-area GEMs will be used as tracking detectors for MOLLER as well. The conceptual designs of GEM detectors for the PVDIS and MOLLER experiments will be presented.

High Z particle Apollo astronaut dosimetry with plastics

NASA Technical Reports Server (NTRS)

Benton, E. V.; Henke, R. P.

1972-01-01

On Apollo missions, the individual astronauts' high Z particle exposure is measured by means of Lexan polycarbonate plastic. These layers form one component of the passive dosimetry packets worn in the constant wear garment. They serve as threshold type, high Z, charged particle track detectors, recording only the very highly ionizing particles. The detectors yield information on the particles' charge, energy, and direction of travel. This data, in turn, is used to obtain the track fluence, the stopping particle density as an integral Z distribution, and the particles' integral LET spectrum. Some of the data gathered on Apollo missions 8-13 is presented.

Real-time Molecular Study of Bystander Effects of Low dose Low LET radiation Using Living Cell Imaging and Nanoparticale Optics

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

Natarajan, Mohan; Xu, Nancy R; Mohan, Sumathy

2013-06-03

In this study two novel approaches are proposed to investigate precisely the low dose low LET radiation damage and its effect on bystander cells in real time. First, a flow shear model system, which would provide us a near in vivo situation where endothelial cells in the presence of extra cellular matrix experiencing continuous flow shear stress, will be used. Endothelial cells on matri-gel (simulated extra cellular matrix) will be subjected to physiological flow shear (that occurs in normal blood vessels). Second, a unique tool (Single nano particle/single live cell/single molecule microscopy and spectroscopy; Figure A) will be used tomore » track the molecular trafficking by single live cell imaging. Single molecule chemical microscopy allows one to single out and study rare events that otherwise might be lost in assembled average measurement, and monitor many target single molecules simultaneously in real-time. Multi color single novel metal nanoparticle probes allow one to prepare multicolor probes (Figure B) to monitor many single components (events) simultaneously and perform multi-complex analysis in real-time. These nano-particles resist to photo bleaching and hence serve as probes for unlimited timeframe of analysis. Single live cell microscopy allows one to image many single cells simultaneously in real-time. With the combination of these unique tools, we will be able to study under near-physiological conditions the cellular and sub-cellular responses (even subtle changes at one molecule level) to low and very low doses of low LET radiation in real time (milli-second or nano-second) at sub-10 nanometer spatial resolution. This would allow us to precisely identify, at least in part, the molecular mediators that are responsible of radiation damage in the irradiated cells and the mediators that are responsible for initiating the signaling in the neighboring cells. Endothelial cells subjected to flow shear (2 dynes/cm2 or 16 dynes/cm2) and exposed to 0.1, 1 and 10 cGy on coverslips will be examined for (a) low LET radiation-induced alterations of cellular function and its physiological relevance in real time; and (b) radiation damage triggered bystander effect on the neighboring unirradiated cells. First, to determine the low LET radiation induced alteration of cellular function we will examine: (i) the real time transformation of single membrane transporters in single living cells; (ii) the pump efficiency of membrane efflux pump of live cells in real time at the molecular level; (iii) the kinetics of single-ligand receptor interaction on single live cell surface (Figure C); and (iv) alteration in chromosome replication in living cell. Second, to study the radiation triggered bystander responses, we will examine one of the key signaling pathway i.e. TNF- alpha/NF-kappa B mediated signaling. TNF-alpha specific nano particle sensors (green) will be developed to detect the releasing dynamics, transport mechanisms and ligand-receptor binding on live cell surface in real time. A second sensor (blue) will be developed to simultaneously monitor the track of NF-kB inside the cell. The proposed nano-particle optics approach would complement our DOE funded study on biochemical mechanisms of TNF-alpha- NF-kappa B-mediated bystander effect.« less

Detection and tracking of a moving target using SAR images with the particle filter-based track-before-detect algorithm.

PubMed

Gao, Han; Li, Jingwen

2014-06-19

A novel approach to detecting and tracking a moving target using synthetic aperture radar (SAR) images is proposed in this paper. Achieved with the particle filter (PF) based track-before-detect (TBD) algorithm, the approach is capable of detecting and tracking the low signal-to-noise ratio (SNR) moving target with SAR systems, which the traditional track-after-detect (TAD) approach is inadequate for. By incorporating the signal model of the SAR moving target into the algorithm, the ambiguity in target azimuth position and radial velocity is resolved while tracking, which leads directly to the true estimation. With the sub-area substituted for the whole area to calculate the likelihood ratio and a pertinent choice of the number of particles, the computational efficiency is improved with little loss in the detection and tracking performance. The feasibility of the approach is validated and the performance is evaluated with Monte Carlo trials. It is demonstrated that the proposed approach is capable to detect and track a moving target with SNR as low as 7 dB, and outperforms the traditional TAD approach when the SNR is below 14 dB.

Detection and Tracking of a Moving Target Using SAR Images with the Particle Filter-Based Track-Before-Detect Algorithm

PubMed Central

Gao, Han; Li, Jingwen

2014-01-01

A novel approach to detecting and tracking a moving target using synthetic aperture radar (SAR) images is proposed in this paper. Achieved with the particle filter (PF) based track-before-detect (TBD) algorithm, the approach is capable of detecting and tracking the low signal-to-noise ratio (SNR) moving target with SAR systems, which the traditional track-after-detect (TAD) approach is inadequate for. By incorporating the signal model of the SAR moving target into the algorithm, the ambiguity in target azimuth position and radial velocity is resolved while tracking, which leads directly to the true estimation. With the sub-area substituted for the whole area to calculate the likelihood ratio and a pertinent choice of the number of particles, the computational efficiency is improved with little loss in the detection and tracking performance. The feasibility of the approach is validated and the performance is evaluated with Monte Carlo trials. It is demonstrated that the proposed approach is capable to detect and track a moving target with SNR as low as 7 dB, and outperforms the traditional TAD approach when the SNR is below 14 dB. PMID:24949640

Scaled Brownian motion: a paradoxical process with a time dependent diffusivity for the description of anomalous diffusion.

PubMed

Jeon, Jae-Hyung; Chechkin, Aleksei V; Metzler, Ralf

2014-08-14

Anomalous diffusion is frequently described by scaled Brownian motion (SBM), a Gaussian process with a power-law time dependent diffusion coefficient. Its mean squared displacement is 〈x(2)(t)〉 ≃ 2K(t)t with K(t) ≃ t(α-1) for 0 < α < 2. SBM may provide a seemingly adequate description in the case of unbounded diffusion, for which its probability density function coincides with that of fractional Brownian motion. Here we show that free SBM is weakly non-ergodic but does not exhibit a significant amplitude scatter of the time averaged mean squared displacement. More severely, we demonstrate that under confinement, the dynamics encoded by SBM is fundamentally different from both fractional Brownian motion and continuous time random walks. SBM is highly non-stationary and cannot provide a physical description for particles in a thermalised stationary system. Our findings have direct impact on the modelling of single particle tracking experiments, in particular, under confinement inside cellular compartments or when optical tweezers tracking methods are used.

Embryogenesis and organogenesis of Carausius morosus under spaceflight conditions.

PubMed

Bucker, H; Facius, R; Horneck, G; Reitz, G; Graul, E H; Berger, H; Hoffken, H; Ruther, W; Heinrich, W; Beaujean, R; Enge, W

1986-01-01

The influence of cosmic radiation and/or microgravity on insect development was studied during the 7 day German Spacelab Mission D1. Eggs of Carausius morosus of five stages differing in sensitivity to radiation and in capacity to regeneration were allowed to continue their development in the BIORACK 22 degrees C incubator, either at microgravity conditions or on the 1 g reference centrifuge. Using the Biostack concept--eggs in monolayers were sandwiched between visual track detectors--and the 1 g reference centrifuge, we were able to separate radiation effects from microgravity effects and also from combined effects of these two factors in space. After retrieval, hatching rates, growth kinetics and anomaly frequencies were determined in the different test samples. The early stages of development turned out to be highly sensitive to single hits of cosmic ray particles as well as to the temporary exposure to microgravity during their development. In some cases, the combined action of radiation and microgravity even amplified the effects exerted by the single parameters of space. Hits by single HZE particles caused early effects, such as body anomalies, as well as late effects, such as retarded growth after hatching. Microgravity exposure lead to a reduced hatching rate. A synergistic action of HZE particle hits and microgravity was established in the unexpectedly high frequency of anomal larvae. However, it cannot be excluded, that cosmic background radiation or low LET HZE particles are also causally involved in damage observed in the microgravity samples.

Microbeam studies of the sensitivity of structures within living cells

NASA Technical Reports Server (NTRS)

Braby, L. A.

1992-01-01

Determining the biological effects of low doses of radiation with high linear energy transfer (LET) is complicated by the stochastic nature of charged-particle interactions. Populations of cells exposed to very low radiation doses contain a few cells which have been hit by a charged particle, while the majority of the cells receive no radiation damage. At somewhat higher doses, a few cells receive two or more events. Because the effects of damage produced by separate events can interact in the cell, we have had to make assumptions about the nature of these interactions in order to interpret the results of the experiments. Many of those assumptions can be tested if we can be sure of the number of charged-particle events which occur in individual cells, and correlate this number with the biological effect. We have developed a special irradiation facility at Pacific Northwest Laboratory (PNL) to control the actual number of charged particle tracks that pass through cell nuclei. The beam from a 2 MeV tandem accelerator is collimated to approximately 5 microns. Cells, grown in special dishes with 1.5 microns thick plastic bottoms, are positioned so that the desired portion of the cell aligns with the collimator. A shutter in the beam line is opened and closed after the desired number of particle tracks has been counted. This approach can be used to investigate the effects of the interaction between irradiated and unirradiated cells in an organized system, as well as to study the effects of spatial and temporal distribution of radiation damage within single cells.(ABSTRACT TRUNCATED AT 250 WORDS).

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

Wu, Chung-Yeh; Wolf, William J.; Levartovsky, Yehonatan

We report the critical role in surface reactions and heterogeneous catalysis of metal atoms with low coordination numbers, such as found at atomic steps and surface defects, is firmly established. But despite the growing availability of tools that enable detailed in situ characterization, so far it has not been possible to document this role directly. Surface properties can be mapped with high spatial resolution, and catalytic conversion can be tracked with a clear chemical signature; however, the combination of the two, which would enable high-spatial-resolution detection of reactions on catalytic surfaces, has rarely been achieved. Single-molecule fluorescence spectroscopy has beenmore » used to image and characterize single turnover sites at catalytic surfaces, but is restricted to reactions that generate highly fluorescing product molecules. Herein the chemical conversion of N-heterocyclic carbene molecules attached to catalytic particles is mapped using synchrotron-radiation-based infrared nanospectroscopy with a spatial resolution of 25 nanometres, which enabled particle regions that differ in reactivity to be distinguished. Lastly, these observations demonstrate that, compared to the flat regions on top of the particles, the peripheries of the particles-which contain metal atoms with low coordination numbers-are more active in catalysing oxidation and reduction of chemically active groups in surface-anchored N-heterocyclic carbene molecules.« less

Single wheel testers, single track testers, and instrumented tractors

USDA-ARS?s Scientific Manuscript database

Single wheel testers and single track testers are used for determining tractive performance characteristics of tires and tracks. Instrumented tractors are useful in determining the tractive performance of tractors. These machines are also used for determining soil-tire and soil-track interactions,...

Solid State Nuclear Track Detectors--I: Track Characteristics and Formation Mechanisms.

ERIC Educational Resources Information Center

Lal, Nand

1991-01-01

Heavily ionizing charged particles produce radiation damage tracks in a wide variety of insulating materials. The experimental properties of these tracks and track recorders are described. The mechanisms by which the tracks are produced are discussed. (Author/KR)

Investigation on microfluidic particles manipulation by holographic 3D tracking strategies

NASA Astrophysics Data System (ADS)

Cacace, Teresa; Paturzo, Melania; Memmolo, Pasquale; Vassalli, Massimo; Fraldi, Massimiliano; Mensitieri, Giuseppe; Ferraro, Pietro

2017-06-01

We demonstrate a 3D holographic tracking method to investigate particles motion in a microfluidic channel while unperturbed while inducing their migration through microfluidic manipulation. Digital holography (DH) in microscopy is a full-field, label-free imaging technique able to provide quantitative phase-contrast. The employed 3D tracking method is articulated in steps. First, the displacements along the optical axis are assessed by numerical refocusing criteria. In particular, an automatic refocusing method to recover the particles axial position is implemented employing a contrast-based refocusing criterion. Then, the transverse position of the in-focus object is evaluated through quantitative phase map segmentation methods and centroid-based 2D tracking strategy. The introduction of DH is thus suggested as a powerful approach for control of particles and biological samples manipulation, as well as a possible aid to precise design and implementation of advanced lab-on-chip microfluidic devices.

New color-based tracking algorithm for joints of the upper extremities

NASA Astrophysics Data System (ADS)

Wu, Xiangping; Chow, Daniel H. K.; Zheng, Xiaoxiang

2007-11-01

To track the joints of the upper limb of stroke sufferers for rehabilitation assessment, a new tracking algorithm which utilizes a developed color-based particle filter and a novel strategy for handling occlusions is proposed in this paper. Objects are represented by their color histogram models and particle filter is introduced to track the objects within a probability framework. Kalman filter, as a local optimizer, is integrated into the sampling stage of the particle filter that steers samples to a region with high likelihood and therefore fewer samples is required. A color clustering method and anatomic constraints are used in dealing with occlusion problem. Compared with the general basic particle filtering method, the experimental results show that the new algorithm has reduced the number of samples and hence the computational consumption, and has achieved better abilities of handling complete occlusion over a few frames.

Scintillator-fiber charged-particle track-imaging detector

NASA Technical Reports Server (NTRS)

Binns, W. R.; Israel, M. H.; Klarmann, J.

1983-01-01

A scintillator-fiber charged-particle track-imaging detector has been developed using a bundle of square cross-section plastic scintillator fiber optics, proximity focused onto an image intensified Charge Injection Device (CID) camera. Detector to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei have been exposed and images of their tracks are obtained. This paper presents details of the detector technique, properties of the tracks obtained, and range measurements of 15 MeV protons stopping in the fiber bundle.

Novel branching particle method for tracking

NASA Astrophysics Data System (ADS)

Ballantyne, David J.; Chan, Hubert Y.; Kouritzin, Michael A.

2000-07-01

Particle approximations are used to track a maneuvering signal given only a noisy, corrupted sequence of observations, as are encountered in target tracking and surveillance. The signal exhibits nonlinearities that preclude the optimal use of a Kalman filter. It obeys a stochastic differential equation (SDE) in a seven-dimensional state space, one dimension of which is a discrete maneuver type. The maneuver type switches as a Markov chain and each maneuver identifies a unique SDE for the propagation of the remaining six state parameters. Observations are constructed at discrete time intervals by projecting a polygon corresponding to the target state onto two dimensions and incorporating the noise. A new branching particle filter is introduced and compared with two existing particle filters. The filters simulate a large number of independent particles, each of which moves with the stochastic law of the target. Particles are weighted, redistributed, or branched, depending on the method of filtering, based on their accordance with the current observation from the sequence. Each filter provides an approximated probability distribution of the target state given all back observations. All three particle filters converge to the exact conditional distribution as the number of particles goes to infinity, but differ in how well they perform with a finite number of particles. Using the exactly known ground truth, the root-mean-squared (RMS) errors in target position of the estimated distributions from the three filters are compared. The relative tracking power of the filters is quantified for this target at varying sizes, particle counts, and levels of observation noise.

Searches for dark matter and new physics with unconventional signatures

NASA Astrophysics Data System (ADS)

Wulz, C.-E.; CMS Collaboration

2017-07-01

Selected results on searches for dark matter and unconventional signatures with the CMS detector are presented. Dark matter searches in channels with one or two jets, single photons, vector bosons, or top and bottom quarks combined with missing momentum in the final states are described. Unusual signatures such as displaced objects, disappearing or kinked tracks, delayed or stopped particles have also been explored. The analyses were performed with proton-proton data recorded at LHC centre-of-mass energies up to 13TeV.

In Vivo Anomalous Diffusion and Weak Ergodicity Breaking of Lipid Granules

NASA Astrophysics Data System (ADS)

Jeon, Jae-Hyung; Tejedor, Vincent; Burov, Stas; Barkai, Eli; Selhuber-Unkel, Christine; Berg-Sørensen, Kirstine; Oddershede, Lene; Metzler, Ralf

2011-01-01

Combining extensive single particle tracking microscopy data of endogenous lipid granules in living fission yeast cells with analytical results we show evidence for anomalous diffusion and weak ergodicity breaking. Namely we demonstrate that at short times the granules perform subdiffusion according to the laws of continuous time random walk theory. The associated violation of ergodicity leads to a characteristic turnover between two scaling regimes of the time averaged mean squared displacement. At longer times the granule motion is consistent with fractional Brownian motion.

Stanley Corrsin Award Lecture: Lagrangian Measurements in Turbulence: From Fundamentals to Applications

NASA Astrophysics Data System (ADS)

Bodenschatz, Eberhard

2014-11-01

In my talk I shall present results from particle tracking experiments in turbulence. After a short review of the history of the field, I shall summarize the most recent technological advances that range form low and high-density particle tracking to direct measurements of the Lagrangian evolution of vorticity. I shall embark on a journey that describes the discoveries made possible by this new technology in the last 15 years. I present results that challenge our understanding of turbulence and show how Lagrangian particle tracking can help us ask questions on turbulent flows that so far were hidden. I shall show how Lagrangian particle tracking may provide important insights into the reversibility of turbulent flows, on vorticity generation, the energy cascade and turbulent mixing. I shall describe the consequences of inertial particle transport on rain formation and end with an outlook on how Lagrangian particle tracking experiments on non-stationary flows in real-world situations may provide high quality data that can support real world engineering problems. I am very thankful for the support by Cornell University, the National Science Foundation, the Research Corporation, the Alfred P. Sloan Foundation, the Kavli Institute for Theoretical Physics, the German Research Foundation, the European Union and the Max Planck Society. I very gratefully acknowledge the excellent partnership with many colleagues in the field of fluid mechanics and turbulence.

High-Rate Capable Floating Strip Micromegas

NASA Astrophysics Data System (ADS)

Bortfeldt, Jonathan; Bender, Michael; Biebel, Otmar; Danger, Helge; Flierl, Bernhard; Hertenberger, Ralf; Lösel, Philipp; Moll, Samuel; Parodi, Katia; Rinaldi, Ilaria; Ruschke, Alexander; Zibell, André

2016-04-01

We report on the optimization of discharge insensitive floating strip Micromegas (MICRO-MEsh GASeous) detectors, fit for use in high-energy muon spectrometers. The suitability of these detectors for particle tracking is shown in high-background environments and at very high particle fluxes up to 60 MHz/cm2. Measurement and simulation of the microscopic discharge behavior have demonstrated the excellent discharge tolerance. A floating strip Micromegas with an active area of 48 cm × 50 cm with 1920 copper anode strips exhibits in 120 GeV pion beams a spatial resolution of 50 μm at detection efficiencies above 95%. Pulse height, spatial resolution and detection efficiency are homogeneous over the detector. Reconstruction of particle track inclination in a single detector plane is discussed, optimum angular resolutions below 5° are observed. Systematic deviations of this μTPC-method are fully understood. The reconstruction capabilities for minimum ionizing muons are investigated in a 6.4 cm × 6.4 cm floating strip Micromegas under intense background irradiation of the whole active area with 20 MeV protons at a rate of 550 kHz. The spatial resolution for muons is not distorted by space charge effects. A 6.4 cm × 6.4 cm floating strip Micromegas doublet with low material budget is investigated in highly ionizing proton and carbon ion beams at particle rates between 2 MHz and 2 GHz. Stable operation up to the highest rates is observed, spatial resolution, detection efficiencies, the multi-hit and high-rate capability are discussed.

Track structure in radiation biology: theory and applications.

PubMed

Nikjoo, H; Uehara, S; Wilson, W E; Hoshi, M; Goodhead, D T

1998-04-01

A brief review is presented of the basic concepts in track structure and the relative merit of various theoretical approaches adopted in Monte-Carlo track-structure codes are examined. In the second part of the paper, a formal cluster analysis is introduced to calculate cluster-distance distributions. Total experimental ionization cross-sections were least-square fitted and compared with the calculation by various theoretical methods. Monte-Carlo track-structure code Kurbuc was used to examine and compare the spectrum of the secondary electrons generated by using functions given by Born-Bethe, Jain-Khare, Gryzinsky, Kim-Rudd, Mott and Vriens' theories. The cluster analysis in track structure was carried out using the k-means method and Hartigan algorithm. Data are presented on experimental and calculated total ionization cross-sections: inverse mean free path (IMFP) as a function of electron energy used in Monte-Carlo track-structure codes; the spectrum of secondary electrons generated by different functions for 500 eV primary electrons; cluster analysis for 4 MeV and 20 MeV alpha-particles in terms of the frequency of total cluster energy to the root-mean-square (rms) radius of the cluster and differential distance distributions for a pair of clusters; and finally relative frequency distribution for energy deposited in DNA, single-strand break and double-strand breaks for 10MeV/u protons, alpha-particles and carbon ions. There are a number of Monte-Carlo track-structure codes that have been developed independently and the bench-marking presented in this paper allows a better choice of the theoretical method adopted in a track-structure code to be made. A systematic bench-marking of cross-sections and spectra of the secondary electrons shows differences between the codes at atomic level, but such differences are not significant in biophysical modelling at the macromolecular level. Clustered-damage evaluation shows: that a substantial proportion of dose ( 30%) is deposited by low-energy electrons; the majority of DNA damage lesions are of simple type; the complexity of damage increases with increased LET, while the total yield of strand breaks remains constant; and at high LET values nearly 70% of all double-strand breaks are of complex type.

Quantitative nanoparticle tracking: applications to nanomedicine.

PubMed

Huang, Feiran; Dempsey, Christopher; Chona, Daniela; Suh, Junghae

2011-06-01

Particle tracking is an invaluable technique to extract quantitative and qualitative information regarding the transport of nanomaterials through complex biological environments. This technique can be used to probe the dynamic behavior of nanoparticles as they interact with and navigate through intra- and extra-cellular barriers. In this article, we focus on the recent developments in the application of particle-tracking technology to nanomedicine, including the study of synthetic and virus-based materials designed for gene and drug delivery. Specifically, we cover research where mean square displacements of nanomaterial transport were explicitly determined in order to quantitatively assess the transport of nanoparticles through biological environments. Particle-tracking experiments can provide important insights that may help guide the design of more intelligent and effective diagnostic and therapeutic nanoparticles.

LET spectra measurements of charged particles in the P0006 experiment on LDEF

NASA Technical Reports Server (NTRS)

Benton, E. V.; Csige, I.; Oda, K.; Henke, R. P.; Frank, A. L.; Benton, E. R.; Frigo, L. A.; Parnell, T. A.; Watts, J. W., Jr.; Derrickson, J. H.

1993-01-01

Measurements are under way of the charged particle radiation environment of the Long Duration Exposure Facility (LDEF) satellite using stacks of plastic nuclear track detectors (PNTD's) placed in different locations of the satellite. In the initial work the charge, energy, and linear energy transfer (LET) spectra of charged particles were measured with CR-39 double layer PNTD's located on the west side of the satellite (Experiment P0006). Primary and secondary stopping heavy ions were measured separately from the more energetic particles. Both trapped and galactic cosmic ray (GCR) particles are included, with the latter component being dominated by relativistic iron particles. The results from the P0006 experiment will be compared with similar measurements in other locations on LDEF with different orientation and shielding conditions. The remarkably detailed investigation of the charged particle radiation environment of the LDEF satellite will lead to a better understanding of the radiation environment of the Space Station Freedom. It will enable more accurate prediction of single event upsets (SEU's) in microelectronics and, especially, more accurate assessment of the risk - contributed by different components of the radiation field (GCR's, trapped protons, secondaries and heavy recoils, etc.) - to the health and safety of crew members.

MONDO: A tracker for the characterization of secondary fast and ultrafast neutrons emitted in particle therapy

NASA Astrophysics Data System (ADS)

Mirabelli, R.; Battistoni, G.; Giacometti, V.; Patera, V.; Pinci, D.; Sarti, A.; Sciubba, A.; Traini, G.; Marafini, M.

2018-01-01

In Particle Therapy (PT) accelerated charged particles and light ions are used for treating tumors. One of the main limitation to the precision of PT is the emission of secondary particles due to the beam interaction with the patient: secondary emitted neutrons can release a significant dose far from the tumor. Therefore, a precise characterization of their flux, production energy and angle distribution is eagerly needed in order to improve the Treatment Planning Systems (TPS) codes. The principal aim of the MONDO (MOnitor for Neutron Dose in hadrOntherapy) project is the development of a tracking device optimized for the detection of fast and ultra-fast secondary neutrons emitted in PT. The detector consists of a matrix of scintillating square fibres coupled with a CMOS-based readout. Here, we present the characterization of the detector tracker prototype and CMOS-based digital SPAD (Single Photon Avalanche Diode) array sensor tested with protons at the Beam Test Facility (Frascati, Italy) and at the Proton Therapy Centre (Trento, Italy), respectively.

Exact Green's functions for a Brownian particle reversibly binding to a fixed target in a finite, two-dimensional, circular domain

NASA Astrophysics Data System (ADS)

Kalay, Ziya

2012-06-01

Despite the apparent need to study reversible reactions between molecules confined to a two-dimensional space such as the cell membrane, exact Green’s functions for this case have not been reported. Here we present exact analytical Green’s functions for a Brownian particle reversibly reacting with a fixed reaction center in a finite two-dimensional circular region with reflecting or absorbing boundaries, considering either a spherically symmetric initial distribution or a particle that is initially bound. We show that Green’s function can be used to predict the effect of measurement uncertainties on the outcome of single-particle/molecule-tracking experiments in which molecular interactions are investigated. Hence, we bridge the gap between previously known solutions in one dimension (Agmon 1984 J. Chem. Phys. 81 2811) and three dimensions (Kim and Shin 1999 Phys. Rev. Lett. 82 1578), and provide an example of how the knowledge of Green’s function can be used to predict experimentally accessible quantities.

Superdiffusion dominates intracellular particle motion in the supercrowded cytoplasm of pathogenic Acanthamoeba castellanii

NASA Astrophysics Data System (ADS)

Reverey, Julia F.; Jeon, Jae-Hyung; Bao, Han; Leippe, Matthias; Metzler, Ralf; Selhuber-Unkel, Christine

2015-06-01

Acanthamoebae are free-living protists and human pathogens, whose cellular functions and pathogenicity strongly depend on the transport of intracellular vesicles and granules through the cytosol. Using high-speed live cell imaging in combination with single-particle tracking analysis, we show here that the motion of endogenous intracellular particles in the size range from a few hundred nanometers to several micrometers in Acanthamoeba castellanii is strongly superdiffusive and influenced by cell locomotion, cytoskeletal elements, and myosin II. We demonstrate that cell locomotion significantly contributes to intracellular particle motion, but is clearly not the only origin of superdiffusivity. By analyzing the contribution of microtubules, actin, and myosin II motors we show that myosin II is a major driving force of intracellular motion in A. castellanii. The cytoplasm of A. castellanii is supercrowded with intracellular vesicles and granules, such that significant intracellular motion can only be achieved by actively driven motion, while purely thermally driven diffusion is negligible.

Surface folding in metals: a mechanism for delamination wear in sliding

PubMed Central

Mahato, Anirban; Guo, Yang; Sundaram, Narayan K.; Chandrasekar, Srinivasan

2014-01-01

Using high-resolution, in situ imaging of a hard, wedge-shaped model asperity sliding against a metal surface, we demonstrate a new mechanism for particle formation and delamination wear. Damage to the residual surface is caused by the occurrence of folds on the free surface of the prow-shaped region ahead of the wedge. This damage manifests itself as shallow crack-like features and surface tears, which are inclined at very acute angles to the surface. The transformation of folds into cracks, tears and particles is directly captured. Notably, a single sliding pass is sufficient to damage the surface, and subsequent passes result in the generation of platelet-like wear particles. Tracking the folding process at every stage from surface bumps to folds to cracks/tears/particles ensures that there is no ambiguity in capturing the mechanism of wear. Because fold formation and consequent delamination are quite general, our findings have broad applicability beyond wear itself, including implications for design of surface generation and conditioning processes. PMID:25197251

Particle Detectors

NASA Astrophysics Data System (ADS)

Grupen, Claus; Shwartz, Boris

2011-09-01

Preface to the first edition; Preface to the second edition; Introduction; 1. Interactions of particles and radiation with matter; 2. Characteristic properties of detectors; 3. Units of radiation measurements and radiation sources; 4. Accelerators; 5. Main physical phenomena used for particle detection and basic counter types; 6. Historical track detectors; 7. Track detectors; 8. Calorimetry; 9. Particle identification; 10. Neutrino detectors; 11. Momentum measurement and muon detection; 12. Ageing and radiation effects; 13. Example of a general-purpose detector: Belle; 14. Electronics; 15. Data analysis; 16. Applications of particle detectors outside particle physics; 17. Glossary; 18. Solutions; 19. Resumé; Appendixes; Index.

User guide for MODPATH version 6 - A particle-tracking model for MODFLOW

USGS Publications Warehouse

Pollock, David W.

2012-01-01

MODPATH is a particle-tracking post-processing model that computes three-dimensional flow paths using output from groundwater flow simulations based on MODFLOW, the U.S. Geological Survey (USGS) finite-difference groundwater flow model. This report documents MODPATH version 6. Previous versions were documented in USGS Open-File Reports 89-381 and 94-464. The program uses a semianalytical particle-tracking scheme that allows an analytical expression of a particle's flow path to be obtained within each finite-difference grid cell. A particle's path is computed by tracking the particle from one cell to the next until it reaches a boundary, an internal sink/source, or satisfies another termination criterion. Data input to MODPATH consists of a combination of MODFLOW input data files, MODFLOW head and flow output files, and other input files specific to MODPATH. Output from MODPATH consists of several output files, including a number of particle coordinate output files intended to serve as input data for other programs that process, analyze, and display the results in various ways. MODPATH is written in FORTRAN and can be compiled by any FORTRAN compiler that fully supports FORTRAN-2003 or by most commercially available FORTRAN-95 compilers that support the major FORTRAN-2003 language extensions.

Ensemble and single particle fluorimetric techniques in concerted action to study the diffusion and aggregation of the glycine receptor α3 isoforms in the cell plasma membrane.

PubMed

Notelaers, Kristof; Smisdom, Nick; Rocha, Susana; Janssen, Daniel; Meier, Jochen C; Rigo, Jean-Michel; Hofkens, Johan; Ameloot, Marcel

2012-12-01

The spatio-temporal membrane behavior of glycine receptors (GlyRs) is known to be of influence on receptor homeostasis and functionality. In this work, an elaborate fluorimetric strategy was applied to study the GlyR α3K and L isoforms. Previously established differential clustering, desensitization and synaptic localization of these isoforms imply that membrane behavior is crucial in determining GlyR α3 physiology. Therefore diffusion and aggregation of homomeric α3 isoform-containing GlyRs were studied in HEK 293 cells. A unique combination of multiple diffraction-limited ensemble average methods and subdiffraction single particle techniques was used in order to achieve an integrated view of receptor properties. Static measurements of aggregation were performed with image correlation spectroscopy (ICS) and, single particle based, direct stochastic optical reconstruction microscopy (dSTORM). Receptor diffusion was measured by means of raster image correlation spectroscopy (RICS), temporal image correlation spectroscopy (TICS), fluorescence recovery after photobleaching (FRAP) and single particle tracking (SPT). The results show a significant difference in diffusion coefficient and cluster size between the isoforms. This reveals a positive correlation between desensitization and diffusion and disproves the notion that receptor aggregation is a universal mechanism for accelerated desensitization. The difference in diffusion coefficient between the clustering GlyR α3L and the non-clustering GlyR α3K cannot be explained by normal diffusion. SPT measurements indicate that the α3L receptors undergo transient trapping and directed motion, while the GlyR α3K displays mild hindered diffusion. These findings are suggestive of differential molecular interaction of the isoforms after incorporation in the membrane. Copyright © 2012 Elsevier B.V. All rights reserved.

AUTOMATIC COUNTER

DOEpatents

Robinson, H.P.

1960-06-01

An automatic counter of alpha particle tracks recorded by a sensitive emulsion of a photographic plate is described. The counter includes a source of mcdulated dark-field illumination for developing light flashes from the recorded particle tracks as the photographic plate is automatically scanned in narrow strips. Photoelectric means convert the light flashes to proportional current pulses for application to an electronic counting circuit. Photoelectric means are further provided for developing a phase reference signal from the photographic plate in such a manner that signals arising from particle tracks not parallel to the edge of the plate are out of phase with the reference signal. The counting circuit includes provision for rejecting the out-of-phase signals resulting from unoriented tracks as well as signals resulting from spurious marks on the plate such as scratches, dust or grain clumpings, etc. The output of the circuit is hence indicative only of the tracks that would be counted by a human operator.

Solar Flare Track Exposure Ages in Regolith Particles: A Calibration for Transmission Electron Microscope Measurements

NASA Technical Reports Server (NTRS)

Berger, Eve L.; Keller, Lindsay P.

2015-01-01

Mineral grains in lunar and asteroidal regolith samples provide a unique record of their interaction with the space environment. Space weathering effects result from multiple processes including: exposure to the solar wind, which results in ion damage and implantation effects that are preserved in the rims of grains (typically the outermost 100 nm); cosmic ray and solar flare activity, which result in track formation; and impact processes that result in the accumulation of vapor-deposited elements, impact melts and adhering grains on particle surfaces. Determining the rate at which these effects accumulate in the grains during their space exposure is critical to studies of the surface evolution of airless bodies. Solar flare energetic particles (mainly Fe-group nuclei) have a penetration depth of a few millimeters and leave a trail of ionization damage in insulating materials that is readily observable by transmission electron microscope (TEM) imaging. The density of solar flare particle tracks is used to infer the length of time an object was at or near the regolith surface (i.e., its exposure age). Track measurements by TEM methods are routine, yet track production rate calibrations have only been determined using chemical etching techniques [e.g., 1, and references therein]. We used focused ion beam-scanning electron microscope (FIB-SEM) sample preparation techniques combined with TEM imaging to determine the track density/exposure age relations for lunar rock 64455. The 64455 sample was used earlier by [2] to determine a track production rate by chemical etching of tracks in anorthite. Here, we show that combined FIB/TEM techniques provide a more accurate determination of a track production rate and also allow us to extend the calibration to solar flare tracks in olivine.

Charged-particle multiplicities in proton-proton collisions at √{s} = 0.9 to 8 TeV

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Rinella, G. Aglieri; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmed, I.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Molina, R. Alfaro; Alici, A.; Alkin, A.; Almaraz, J. R. M.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Prado, C. Alves Garcia; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Camejo, A. Batista; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Martinez, H. Bello; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Böttger, S.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Diaz, L. Calero; Caliva, A.; Villar, E. Calvo; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castellanos, J. Castillo; Castro, A. J.; Casula, E. A. R.; Sanchez, C. Ceballos; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Barroso, V. Chibante; Chinellato, D. D.; Cho, S.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Balbastre, G. Conesa; Valle, Z. Conesa del; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Morales, Y. Corrales; Maldonado, I. Cortés; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Albino, R. Cruz; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; De, S.; De Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; Deplano, C.; Dhankher, P.; Di Bari, D.; Di Mauro, A.; Di Nezza, P.; Corchero, M. A. Diaz; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Gimenez, D. Domenicis; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Engel, H.; Epple, E.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Téllez, A. Fernández; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Girard, M. Fusco; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Coral, D. M. Goméz; Ramirez, A. Gomez; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Grachov, O. A.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Harris, J. W.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Corral, G. Herrera; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hippolyte, B.; Hosokawa, R.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Inaba, M.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jachołkowski, A.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jahnke, C.; Jakubowska, M. J.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Bustamante, R. T. Jimenez; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Uysal, A. Karasu; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Khan, M. Mohisin; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, B.; Kim, D. W.; Kim, D. J.; Kim, D.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobayashi, T.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Meethaleveedu, G. Koyithatta; Králik, I.; Kravčáková, A.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kweon, M. J.; Kwon, Y.; Pointe, S. L. La; Rocca, P. La; de Guevara, P. Ladron; Fernandes, C. Lagana; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Lehas, F.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; Monzón, I. León; Vargas, H. León; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Lopez, X.; Torres, E. López; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Cervantes, I. Maldonado; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Blanco, J. Martin; Martinengo, P.; Martínez, M. I.; García, G. Martínez; Pedreira, M. Martinez; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; Mcdonald, D.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Pérez, J. Mercado; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Zetina, L. Montaño; Montes, E.; De Godoy, D. A. Moreira; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Munzer, R. H.; Murray, S.; Musa, L.; Musinsky, J.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; da Luz, H. Natal; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Silva, A. C. Oliveira Da; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Velasquez, A. Ortiz; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pal, S. K.; Pan, J.; Pandey, A. K.; Papcun, P.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Peitzmann, T.; Costa, H. Pereira Da; Filho, E. Pereira De Oliveira; Peresunko, D.; Lara, C. E. Pérez; Lezama, E. Perez; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; oskoń, M. Pł; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rocco, E.; Cahuantzi, M. Rodríguez; Manso, A. Rodriguez; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Montero, A. J. Rubio; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Sozzi, F.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Stachel, J.; Stan, I.; Stefanek, G.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Szabo, A.; de Toledo, A. Szanto; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tangaro, M. A.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Muñoz, G. Tejeda; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trombetta, G.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Palomo, L. Valencia; Vallero, S.; Van Der Maarel, J.; Van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vyvre, P. Vande; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Limón, S. Vergara; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Baillie, O. Villalobos; Tello, A. Villatoro; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yang, H.; Yang, P.; Yano, S.; Yasar, C.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.

2017-01-01

A detailed study of pseudorapidity densities and multiplicity distributions of primary charged particles produced in proton-proton collisions, at √{s} = 0.9, 2.36, 2.76, 7 and 8 TeV, in the pseudorapidity range |η |<2, was carried out using the ALICE detector. Measurements were obtained for three event classes: inelastic, non-single diffractive and events with at least one charged particle in the pseudorapidity interval |η |<1. The use of an improved track-counting algorithm combined with ALICE's measurements of diffractive processes allows a higher precision compared to our previous publications. A KNO scaling study was performed in the pseudorapidity intervals |η |< 0.5, 1.0 and 1.5. The data are compared to other experimental results and to models as implemented in Monte Carlo event generators PHOJET and recent tunes of PYTHIA6, PYTHIA8 and EPOS.

Charged-particle multiplicities in proton–proton collisions at $$\\sqrt{s} = 0.9$$ s = 0.9 to 8 TeV

DOE PAGES

Adam, J.; Adamová, D.; Aggarwal, M. M.; ...

2017-01-17

A detailed study of pseudorapidity densities and multiplicity distributions of primary charged particles produced in proton–proton collisions, at s= 0.9, 2.36, 2.76, 7 and 8 TeV, in the pseudorapidity range | η| < 2 , was carried out using the ALICE detector. Measurements were obtained for three event classes: inelastic, non-single diffractive and events with at least one charged particle in the pseudorapidity interval | η| < 1. The use of an improved track-counting algorithm combined with ALICE’s measurements of diffractive processes allows a higher precision compared to our previous publications. A KNO scaling study was performed in the pseudorapiditymore » intervals | η| < 0.5, 1.0 and 1.5. The data are compared to other experimental results and to models as implemented in Monte Carlo event generators PHOJET and recent tunes of PYTHIA6, PYTHIA8 and EPOS.« less

Non-invasive studies of multiphase flow in process equipment. Positron emission particle tracking technique

NASA Astrophysics Data System (ADS)

Balakin, B. V.; Adamsen, T. C. H.; Chang, Y.-F.; Kosinski, P.; Hoffmann, A. C.

2017-01-01

Positron emission particle tracking (PEPT) is a novel experimental technique for non-invasive inspection of industrial fluid/particle flows. The method is based on the dynamic positioning of a positron-emitting, flowing object (particle) performed through the sensing of annihilation events and subsequent numerical treatment to determine the particle position. The present paper shows an integrated overview of PEPT studies which were carried out using a new PET scanner in the Bergen University Hospital to study multiphase flows in different geometric configurations.

New Mexico Play Fairway Analysis: Particle Tracking ArcGIS Map Packages

DOE Data Explorer

Jeff Pepin

2015-11-15

These are map packages used to visualize geochemical particle-tracking analysis results in ArcGIS. It includes individual map packages for several regions of New Mexico including: Acoma, Rincon, Gila, Las Cruces, Socorro and Truth or Consequences.

Photoluminescent diamond nanoparticles for cell labeling: study of the uptake mechanism in mammalian cells.

PubMed

Faklaris, Orestis; Joshi, Vandana; Irinopoulou, Theano; Tauc, Patrick; Sennour, Mohamed; Girard, Hugues; Gesset, Céline; Arnault, Jean-Charles; Thorel, Alain; Boudou, Jean-Paul; Curmi, Patrick A; Treussart, François

2009-12-22

Diamond nanoparticles (nanodiamonds) have been recently proposed as new labels for cellular imaging. For small nanodiamonds (size <40 nm), resonant laser scattering and Raman scattering cross sections are too small to allow single nanoparticle observation. Nanodiamonds can, however, be rendered photoluminescent with a perfect photostability at room temperature. Such a remarkable property allows easier single-particle tracking over long time scales. In this work, we use photoluminescent nanodiamonds of size <50 nm for intracellular labeling and investigate the mechanism of their uptake by living cells. By blocking selectively different uptake processes, we show that nanodiamonds enter cells mainly by endocytosis, and converging data indicate that it is clathrin-mediated. We also examine nanodiamond intracellular localization in endocytic vesicles using immunofluorescence and transmission electron microscopy. We find a high degree of colocalization between vesicles and the biggest nanoparticles or aggregates, while the smallest particles appear free in the cytosol. Our results pave the way for the use of photoluminescent nanodiamonds in targeted intracellular labeling or biomolecule delivery.

Measuring a diffusion coefficient by single-particle tracking: statistical analysis of experimental mean squared displacement curves.

PubMed

Ernst, Dominique; Köhler, Jürgen

2013-01-21

We provide experimental results on the accuracy of diffusion coefficients obtained by a mean squared displacement (MSD) analysis of single-particle trajectories. We have recorded very long trajectories comprising more than 1.5 × 10(5) data points and decomposed these long trajectories into shorter segments providing us with ensembles of trajectories of variable lengths. This enabled a statistical analysis of the resulting MSD curves as a function of the lengths of the segments. We find that the relative error of the diffusion coefficient can be minimized by taking an optimum number of points into account for fitting the MSD curves, and that this optimum does not depend on the segment length. Yet, the magnitude of the relative error for the diffusion coefficient does, and achieving an accuracy in the order of 10% requires the recording of trajectories with about 1000 data points. Finally, we compare our results with theoretical predictions and find very good qualitative and quantitative agreement between experiment and theory.

Developing a particle tracking surrogate model to improve inversion of ground water - Surface water models

NASA Astrophysics Data System (ADS)

Cousquer, Yohann; Pryet, Alexandre; Atteia, Olivier; Ferré, Ty P. A.; Delbart, Célestine; Valois, Rémi; Dupuy, Alain

2018-03-01

The inverse problem of groundwater models is often ill-posed and model parameters are likely to be poorly constrained. Identifiability is improved if diverse data types are used for parameter estimation. However, some models, including detailed solute transport models, are further limited by prohibitive computation times. This often precludes the use of concentration data for parameter estimation, even if those data are available. In the case of surface water-groundwater (SW-GW) models, concentration data can provide SW-GW mixing ratios, which efficiently constrain the estimate of exchange flow, but are rarely used. We propose to reduce computational limits by simulating SW-GW exchange at a sink (well or drain) based on particle tracking under steady state flow conditions. Particle tracking is used to simulate advective transport. A comparison between the particle tracking surrogate model and an advective-dispersive model shows that dispersion can often be neglected when the mixing ratio is computed for a sink, allowing for use of the particle tracking surrogate model. The surrogate model was implemented to solve the inverse problem for a real SW-GW transport problem with heads and concentrations combined in a weighted hybrid objective function. The resulting inversion showed markedly reduced uncertainty in the transmissivity field compared to calibration on head data alone.

Simulations of DSB Yields and Radiation-induced Chromosomal Aberrations in Human Cells Based on the Stochastic Track Structure Induced by HZE Particles

NASA Technical Reports Server (NTRS)

Ponomarev, Artem; Plante, Ianik; George, Kerry; Wu, Honglu

2014-01-01

The formation of double-strand breaks (DSBs) and chromosomal aberrations (CAs) is of great importance in radiation research and, specifically, in space applications. We are presenting a new particle track and DNA damage model, in which the particle stochastic track structure is combined with the random walk (RW) structure of chromosomes in a cell nucleus. The motivation for this effort stems from the fact that the model with the RW chromosomes, NASARTI (NASA radiation track image) previously relied on amorphous track structure, while the stochastic track structure model RITRACKS (Relativistic Ion Tracks) was focused on more microscopic targets than the entire genome. We have combined chromosomes simulated by RWs with stochastic track structure, which uses nanoscopic dose calculations performed with the Monte-Carlo simulation by RITRACKS in a voxelized space. The new simulations produce the number of DSBs as function of dose and particle fluence for high-energy particles, including iron, carbon and protons, using voxels of 20 nm dimension. The combined model also calculates yields of radiation-induced CAs and unrejoined chromosome breaks in normal and repair deficient cells. The joined computational model is calibrated using the relative frequencies and distributions of chromosomal aberrations reported in the literature. The model considers fractionated deposition of energy to approximate dose rates of the space flight environment. The joined model also predicts of the yields and sizes of translocations, dicentrics, rings, and more complex-type aberrations formed in the G0/G1 cell cycle phase during the first cell division after irradiation. We found that the main advantage of the joined model is our ability to simulate small doses: 0.05-0.5 Gy. At such low doses, the stochastic track structure proved to be indispensable, as the action of individual delta-rays becomes more important.

Simulations of DSB Yields and Radiation-induced Chromosomal Aberrations in Human Cells Based on the Stochastic Track Structure iIduced by HZE Particles

NASA Technical Reports Server (NTRS)

Ponomarev, Artem; Plante, Ianik; George, Kerry; Wu, Honglu

2014-01-01

The formation of double-strand breaks (DSBs) and chromosomal aberrations (CAs) is of great importance in radiation research and, specifically, in space applications. We are presenting a new particle track and DNA damage model, in which the particle stochastic track structure is combined with the random walk (RW) structure of chromosomes in a cell nucleus. The motivation for this effort stems from the fact that the model with the RW chromosomes, NASARTI (NASA radiation track image) previously relied on amorphous track structure, while the stochastic track structure model RITRACKS (Relativistic Ion Tracks) was focused on more microscopic targets than the entire genome. We have combined chromosomes simulated by RWs with stochastic track structure, which uses nanoscopic dose calculations performed with the Monte-Carlo simulation by RITRACKS in a voxelized space. The new simulations produce the number of DSBs as function of dose and particle fluence for high-energy particles, including iron, carbon and protons, using voxels of 20 nm dimension. The combined model also calculates yields of radiation-induced CAs and unrejoined chromosome breaks in normal and repair deficient cells. The joined computational model is calibrated using the relative frequencies and distributions of chromosomal aberrations reported in the literature. The model considers fractionated deposition of energy to approximate dose rates of the space flight environment. The joined model also predicts of the yields and sizes of translocations, dicentrics, rings, and more complex-type aberrations formed in the G0/G1 cell cycle phase during the first cell division after irradiation. We found that the main advantage of the joined model is our ability to simulate small doses: 0.05-0.5 Gy. At such low doses, the stochastic track structure proved to be indispensable, as the action of individual delta-rays becomes more important.

A Twist on the Richtmyer-Meshkov Instability

NASA Astrophysics Data System (ADS)

Rollin, Bertrand; Koneru, Rahul; Ouellet, Frederick

2017-11-01

The Richtmyer-Meshkov instability is caused by the interaction of a shock wave with a perturbed interface between two fluids of different densities. Typical contexts in which it plays a key role include inertial confinement fusion, supernovae or scramjets. However, little is known of the phenomenology of this instability if one of the interacting media is a dense solid-particle phase. In the context of an explosive dispersal of particles, this gas-particle variant of the Richtmyer-Meshkov instability may play a role in the late time formation of aerodynamically stable particle jets. Thus, this numerical experiment aims at shedding some light on this phenomenon with the help of high fidelity numerical simulations. Using a Eulerian-Lagrangian approach, we track trajectories of computational particles composing an initially corrugated solid particle curtain, in a two-dimensional planar geometry. This study explores the effects of the initial shape (designed using single mode and multimode perturbations) and volume fraction of the particle curtain on its subsequent evolution. Complexities associated with compaction of the curtain of particles to the random close packing limit are avoided by constraining simulations to modest initial volume fraction of particles. This work was supported by the U.S. DoE, NNSA, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

Effects of nano-SiO{sub 2} particles on surface tracking characteristics of silicone rubber composites

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

Liu, Yong, E-mail: tjuliuyong@tju.edu.cn; Li, Zhonglei; Du, Boxue

Compared with neat silicone rubber composites (SiRCs), SiRCs filled with nano-sized SiO{sub 2} particles at weight ratios from 0.1 to 1.0 wt. % exhibit a higher surface flashover voltage and a greater resistance to surface tracking. Scanning electron microscopy images of tracking morphologies indicate that the SiO{sub 2} particles are situated in close proximity to the polymeric chains and act as bridges to stabilize the chains and maintain the structure of the composite. Higher concentrations of nano-sized SiO{sub 2} particles, however, (above 0.3 wt. %) produce defects in the molecular network which lead to reductions in both the surface flashover voltage and the resistancemore » to surface tracking, although these reduced values are still superior to those of neat SiRCs. Therefore, SiRCs filled with nano-sized SiO{sub 2} particles, especially at an optimal weight ratio (0.1 to 0.3 wt. %), may have significant potential applications as outdoor insulators for power systems.« less

Tilted Light Sheet Microscopy with 3D Point Spread Functions for Single-Molecule Super-Resolution Imaging in Mammalian Cells.

PubMed

Gustavsson, Anna-Karin; Petrov, Petar N; Lee, Maurice Y; Shechtman, Yoav; Moerner, W E

2018-02-01

To obtain a complete picture of subcellular nanostructures, cells must be imaged with high resolution in all three dimensions (3D). Here, we present tilted light sheet microscopy with 3D point spread functions (TILT3D), an imaging platform that combines a novel, tilted light sheet illumination strategy with engineered long axial range point spread functions (PSFs) for low-background, 3D super localization of single molecules as well as 3D super-resolution imaging in thick cells. TILT3D is built upon a standard inverted microscope and has minimal custom parts. The axial positions of the single molecules are encoded in the shape of the PSF rather than in the position or thickness of the light sheet, and the light sheet can therefore be formed using simple optics. The result is flexible and user-friendly 3D super-resolution imaging with tens of nm localization precision throughout thick mammalian cells. We validated TILT3D for 3D super-resolution imaging in mammalian cells by imaging mitochondria and the full nuclear lamina using the double-helix PSF for single-molecule detection and the recently developed Tetrapod PSF for fiducial bead tracking and live axial drift correction. We envision TILT3D to become an important tool not only for 3D super-resolution imaging, but also for live whole-cell single-particle and single-molecule tracking.

Particle tracking experiments in match-index-refraction porous media.

PubMed

Lachhab, Ahmed; Zhang, You-Kuan; Muste, Marian V I

2008-01-01

A low-cost, noninvasive, three-dimensional (3D), particle tracking velocimetry system was designed and built to investigate particle movement in match-index-refraction porous media. Both a uniform load of the glass beads of the same diameter and a binary load of the glass beads of two diameters were used. The purpose of the experiments is to study the effect of the two loads on the trajectories, velocity distribution, and spreading of small physical particles. A total of 35 particles were released and tracked in the uniform load and 46 in the binary load. The 3D trajectory of each particle was recorded with two video camcorders and analyzed. It is found that the particle's velocity, trajectory, and spreading are very sensitive to its initial location and that the smaller pore size or heterogeneity in the binary load increases the particles' velocity and enhances their spreading as compared with the uniform load. The experiments also verified the previous finding that the distribution of the particle velocities are lognormal in the longitudinal direction and Gaussian in two transverse directions and that the particle spreading is much larger along the longitudinal direction than along the traverse directions.

Emissions from Ships with respect to Their Effects on Clouds.

NASA Astrophysics Data System (ADS)

Hobbs, Peter V.; Garrett, Timothy J.; Ferek, Ronald J.; Strader, Scott R.; Hegg, Dean A.; Frick, Glendon M.; Hoppel, William A.; Gasparovic, Richard F.; Russell, Lynn M.; Johnson, Douglas W.; O'Dowd, Colin; Durkee, Philip A.; Nielsen, Kurt E.; Innis, George

2000-08-01

Emissions of particles, gases, heat, and water vapor from ships are discussed with respect to their potential for changing the microstructure of marine stratiform clouds and producing the phenomenon known as `ship tracks.' Airborne measurements are used to derive emission factors of SO2 and NO from diesel-powered and steam turbine-powered ships, burning low-grade marine fuel oil (MFO); they were 15-89 and 2-25 g kg1 of fuel burned, respectively. By contrast a steam turbine-powered ship burning high-grade navy distillate fuel had an SO2 emission factor of 6 g kg1.Various types of ships, burning both MFO and navy distillate fuel, emitted from 4 × 1015 to 2 × 1016 total particles per kilogram of fuel burned (4 × 1015-1.5 × 1016 particles per second). However, diesel-powered ships burning MFO emitted particles with a larger mode radius (0.03-0.05 m) and larger maximum sizes than those powered by steam turbines burning navy distillate fuel (mode radius 0.02 m). Consequently, if the particles have similar chemical compositions, those emitted by diesel ships burning MFO will serve as cloud condensation nuclei (CCN) at lower supersaturations (and will therefore be more likely to produce ship tracks) than the particles emitted by steam turbine ships burning distillate fuel. Since steam turbine-powered ships fueled by MFO emit particles with a mode radius similar to that of diesel-powered ships fueled by MFO, it appears that, for given ambient conditions, the type of fuel burned by a ship is more important than the type of ship engine in determining whether or not a ship will produce a ship track. However, more measurements are needed to test this hypothesis.The particles emitted from ships appear to be primarily organics, possibly combined with sulfuric acid produced by gas-to-particle conversion of SO2. Comparison of model results with measurements in ship tracks suggests that the particles from ships contain only about 10% water-soluble materials. Measurements of the total particles entering marine stratiform clouds from diesel-powered ships fueled by MFO, and increases in droplet concentrations produced by these particles, show that only about 12% of the particles serve as CCN.The fluxes of heat and water vapor from ships are estimated to be 2-22 MW and 0.5-1.5 kg s1, respectively. These emissions rarely produced measurable temperature perturbations, and never produced detectable perturbations in water vapor, in the plumes from ships. Nuclear-powered ships, which emit heat but negligible particles, do not produce ship tracks. Therefore, it is concluded that heat and water vapor emissions do not play a significant role in ship track formation and that particle emissions, particularly from those burning low-grade fuel oil, are responsible for ship track formation. Subsequent papers in this special issue discuss and test these hypotheses.

Charge Identification of Highly Ionizing Particles in Desensitized Nuclear Emulsion Using High Speed Read-Out System

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

Toshito, T.; Kodama, K.; Yusa, K.

2006-05-10

We performed an experimental study of charge identification of heavy ions from helium to carbon having energy of about 290 MeV/u using an emulsion chamber. Emulsion was desensitized by means of forced fading (refreshing) to expand a dynamic range of response to highly charged particles. For the track reconstruction and charge identification, the fully automated high speed emulsion read-out system, which was originally developed for identifying minimum ionizing particles, was used without any modification. Clear track by track charge identification up to Z=6 was demonstrated. The refreshing technique has proved to be a powerful technique to expand response of emulsionmore » film to highly ionizing particles.« less

Elastic collisions of classical point particles on a finite frictionless linear track with perfectly reflecting endpoints

NASA Astrophysics Data System (ADS)

DeLuca, R.

2006-03-01

Repeated elastic collisions of point particles on a finite frictionless linear track with perfectly reflecting endpoints are considered. The problem is analysed by means of an elementary linear algebra approach. It is found that, starting with a state consisting of a projectile particle in motion at constant velocity and a target particle at rest in a fixed known position, the points at which collisions occur on track, when plotted versus progressive numerals, corresponding to the collisions themselves, show periodic patterns for a rather large choice of values of the initial position x(0) and on the mass ratio r. For certain values of these parameters, however, only regular behaviour over a large number of collisions is detected.

Balancing Conflicting Requirements for Grid and Particle Decomposition in Continuum-Lagrangian Solvers

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

Sitaraman, Hariswaran; Grout, Ray

2015-10-30

The load balancing strategies for hybrid solvers that involve grid based partial differential equation solution coupled with particle tracking are presented in this paper. A typical Message Passing Interface (MPI) based parallelization of grid based solves are done using a spatial domain decomposition while particle tracking is primarily done using either of the two techniques. One of the techniques is to distribute the particles to MPI ranks to whose grid they belong to while the other is to share the particles equally among all ranks, irrespective of their spatial location. The former technique provides spatial locality for field interpolation butmore » cannot assure load balance in terms of number of particles, which is achieved by the latter. The two techniques are compared for a case of particle tracking in a homogeneous isotropic turbulence box as well as a turbulent jet case. We performed a strong scaling study for more than 32,000 cores, which results in particle densities representative of anticipated exascale machines. The use of alternative implementations of MPI collectives and efficient load equalization strategies are studied to reduce data communication overheads.« less

Particle-tracking analysis of contributing areas of public-supply wells in simple and complex flow systems, Cape Cod, Massachusetts

USGS Publications Warehouse

Barlow, P.M.

1994-01-01

Steady-state, two-and three-dimensional, ground-water flow models coupled with a particle- tracking program were evaluated to determine their effectiveness in delineating contributing areas of existing and hypothetical public-supply wells pumping from two contrasting stratified-drift aquifers of Cape Cod, Mass. Several of the contri- buting areas delineated by use of the three- dimensional models do not conform to simple ellipsoidal shapes that are typically delineated by use of a two-dimensional analytical and numerical modeling techniques, include dis- continuous areas of the water table, and do not surround the wells. Because two-dimensional areal models do not account for vertical flow, they cannot adequately represent many of the hydro- geologic and well-design variables that were shown to complicate the delineation of contributing areas in these flow systems, including the presence of discrete lenses of 1ow hydraulic conductivity, large ratios of horizontal to ver- tical hydraulic conductivity, shallow streams, partially penetrating supply wells, and 1ow pumping rates (less than 0.1 million gallons per day). Nevertheless, contributing areas delineated for two wells in the simpler of the two flow systems--a thin (less than 100 feet), single- layer, uniform aquifer with near-ideal boundary conditions--were not significantly different for the two- or three-dimensional models of the natural system, for a pumping rate of 0.5 million gallons per day. Use of particle tracking helped identify the source of water to simulated wells, which included precipitation recharge, wastewater return flow, and pond water. Pond water and wastewater return flow accounted for as much as 73 and 40 percent, respectively, of the water captured by simulated wells.

Tracking multiple particles in fluorescence time-lapse microscopy images via probabilistic data association.

PubMed

Godinez, William J; Rohr, Karl

2015-02-01

Tracking subcellular structures as well as viral structures displayed as 'particles' in fluorescence microscopy images yields quantitative information on the underlying dynamical processes. We have developed an approach for tracking multiple fluorescent particles based on probabilistic data association. The approach combines a localization scheme that uses a bottom-up strategy based on the spot-enhancing filter as well as a top-down strategy based on an ellipsoidal sampling scheme that uses the Gaussian probability distributions computed by a Kalman filter. The localization scheme yields multiple measurements that are incorporated into the Kalman filter via a combined innovation, where the association probabilities are interpreted as weights calculated using an image likelihood. To track objects in close proximity, we compute the support of each image position relative to the neighboring objects of a tracked object and use this support to recalculate the weights. To cope with multiple motion models, we integrated the interacting multiple model algorithm. The approach has been successfully applied to synthetic 2-D and 3-D images as well as to real 2-D and 3-D microscopy images, and the performance has been quantified. In addition, the approach was successfully applied to the 2-D and 3-D image data of the recent Particle Tracking Challenge at the IEEE International Symposium on Biomedical Imaging (ISBI) 2012.

Discriminative detection of deposited radon daughters on CR-39 track detectors using TRIAC II code

NASA Astrophysics Data System (ADS)

Patiris, D. L.; Ioannides, K. G.

2009-07-01

A method for detecting deposited 218Po and 214Po by a spectrometric study of CR-39 solid state nuclear track detectors is described. The method is based on the application of software imposed selection criteria, concerning the geometrical and optical properties of the tracks, which correspond to tracks created by alpha particles of specific energy falling on the detector at given angles of incidence. The selection criteria were based on a preliminary study of tracks' parameters (major and minor axes and mean value of brightness), using the TRIAC II code. Since no linear relation was found between the energy and the geometric characteristics of the tracks (major and minor axes), we resorted to the use of an additional parameter in order to classify the tracks according to the particles' energy. Since the brightness of tracks is associated with the tracks' depth, the mean value of brightness was chosen as the parameter of choice. To reduce the energy of the particles, which are emitted by deposited 218Po and 214Po into a quantifiable range, the detectors were covered with an aluminum absorber material. In this way, the discrimination of radon's daughters was finally accomplished by properly selecting amongst all registered tracks. This method could be applied as a low cost tool for the study of the radon's daughters behavior in air.

Nuclear particle detection using a track-recording solid

NASA Technical Reports Server (NTRS)

Weber, M.; Weber, D.

1984-01-01

The design of the nuclear particle detector located in Purdue University's Get Away Special package which was flown aboard STS-7 is detailed. The experiment consisted of a stack of particle-detecting polymer sheets. The sheets show positive results of tracks throughout the block. A slide of each sheet was made for further analysis. Recommendations for similar experiments performed in the future are discussed.

Perspectives on individual to ensembles of ambient fine and ultrafine particles and their sources

NASA Astrophysics Data System (ADS)

Bein, Keith James

By combining Rapid Single-ultrafine-particle Mass Spectrometry (RSMS) measurements during the Pittsburgh Supersite experiment with a large array of concurrent PM, gas and meteorological data, a synthesis of data and analyses is employed to characterize sources, emission trends and dynamics of ambient fine and ultrafine particles. Combinatorial analyses elicit individual to ensemble descriptions of particles, their sources, their changes in state from atmospheric processing and the scales of motion driving their transport and dynamics. Major results include (1) Particle size and composition are strong indicators of sources/source categories and real-time measurements allow source attribution at the single particle and point source level. (2) Single particle source attribution compares well to factor analysis of chemically-speciated bulk phase data and both resulted in similar conclusions but independently revealed new sources. (3) RSMS data can quantitatively estimate composition-resolved, number-based particle size distribution. Comparison to mass-based data yielded new information about physical and chemical properties of particles and instrument sensitivity. (4) Source-specific signatures and real-time monitoring allow passing plumes to be tracked and characterized. (5) The largest of three identified coal combustion sources emits ˜ 2.4 x 10 17 primary submicron particles per second. (6) Long-range transport has a significant impact on the eastern U.S. including specific influences of eight separate wildfire events. (7) Pollutant dynamics in the Pittsburgh summertime air shed, and Northeastern U.S., is characterized by alternating periods of stagnation and cleansing. The eight wildfire events were detected in between seven successive stagnation events. (8) Connections exist between boreal fire activity, southeast subsiding transport of the emissions, alternating periods of stagnation and cleansing at the receptor and the structure and propagation of extratropical waves. (9) Wildfire emissions can severely impact preexisting pollutant concentrations and physical and chemical processes at the receptor. (10) High-severity crown fires in boreal Canada emit ˜ 1.2 x 1015 particles/kg biomass burned. (11) In 1998, wildfire activity in the circumpolar boreal forest emitted ˜ 8 x 1026 particles, representing ˜ 14% of global wildland fire emissions. Results and conclusions address future scientific objectives in understanding effects of particles on human health and global climate change.

Combining particle-tracking and geochemical data to assess public supply well vulnerability to arsenic and uranium

USGS Publications Warehouse

Hinkle, S.R.; Kauffman, L.J.; Thomas, M.A.; Brown, C.J.; McCarthy, K.A.; Eberts, S.M.; Rosen, Michael R.; Katz, B.G.

2009-01-01

Flow-model particle-tracking results and geochemical data from seven study areas across the United States were analyzed using three statistical methods to test the hypothesis that these variables can successfully be used to assess public supply well vulnerability to arsenic and uranium. Principal components analysis indicated that arsenic and uranium concentrations were associated with particle-tracking variables that simulate time of travel and water fluxes through aquifer systems and also through specific redox and pH zones within aquifers. Time-of-travel variables are important because many geochemical reactions are kinetically limited, and geochemical zonation can account for different modes of mobilization and fate. Spearman correlation analysis established statistical significance for correlations of arsenic and uranium concentrations with variables derived using the particle-tracking routines. Correlations between uranium concentrations and particle-tracking variables were generally strongest for variables computed for distinct redox zones. Classification tree analysis on arsenic concentrations yielded a quantitative categorical model using time-of-travel variables and solid-phase-arsenic concentrations. The classification tree model accuracy on the learning data subset was 70%, and on the testing data subset, 79%, demonstrating one application in which particle-tracking variables can be used predictively in a quantitative screening-level assessment of public supply well vulnerability. Ground-water management actions that are based on avoidance of young ground water, reflecting the premise that young ground water is more vulnerable to anthropogenic contaminants than is old ground water, may inadvertently lead to increased vulnerability to natural contaminants due to the tendency for concentrations of many natural contaminants to increase with increasing ground-water residence time.

Shock dynamics of two-lane driven lattice gases

NASA Astrophysics Data System (ADS)

Schiffmann, Christoph; Appert-Rolland, Cécile; Santen, Ludger

2010-06-01

Driven lattice gases such as those of the ASEP model are useful tools for the modelling of various stochastic transport processes carried out by self-driven particles, such as molecular motors or vehicles in road traffic. Often these processes take place in one-dimensional systems offering several tracks to the particles, and in many cases the particles are able to change track with a given rate. In this work we consider the case of strong coupling where the rate of hopping along the tracks and the exchange rates are of the same order, and show how a phenomenological approach based on a domain wall theory can be used to describe the dynamics of the system. In particular, the domain walls on the different tracks form pairs, whose dynamics dominate the behaviour of the system.

Interactions and Translational Dynamics of Phosphatidylinositol Bisphosphate (PIP2) Lipids in Asymmetric Lipid Bilayers.

PubMed

Shi, Xiaojun; Kohram, Maryam; Zhuang, Xiaodong; Smith, Adam W

2016-02-23

Phosphatidylinositol phosphate (PIP) lipids are critical to many cell signaling pathways, in part by acting as molecular beacons that recruit peripheral membrane proteins to specific locations within the plasma membrane. Understanding the biophysics of PIP-protein interactions is critical to developing a chemically detailed model of cell communication. Resolving such interactions is challenging, even in model membrane systems, because of the difficulty in preparing PIP-containing membranes with high fluidity and integrity. Here we report on a simple, vesicle-based protocol for preparing asymmetric supported lipid bilayers in which fluorescent PIP lipid analogues are found only on the top leaflet of the supported membrane facing the bulk solution. With this asymmetric distribution of lipids between the leaflets, the fluorescent signal from the PIP lipid analogue reports directly on interactions between the peripheral molecules and the top leaflet of the membrane. Asymmetric PIP-containing bilayers are an ideal platform to investigate the interaction of PIP with peripheral membrane proteins using fluorescence-based imaging approaches. We demonstrate their usefulness here with a combined fluorescence correlation spectroscopy and single particle tracking study of the interaction between PIP2 lipids and a polycationic polymer, quaternized polyvinylpyridine (QPVP). With this approach we are able to quantify the microscopic features of the mobility coupling between PIP2 lipids and polybasic QPVP. With single particle tracking we observe individual PIP2 lipids switch from Brownian to intermittent motion as they become transiently trapped by QPVP.

Aerosol mass spectrometry systems and methods

DOEpatents

Fergenson, David P.; Gard, Eric E.

2013-08-20

A system according to one embodiment includes a particle accelerator that directs a succession of polydisperse aerosol particles along a predetermined particle path; multiple tracking lasers for generating beams of light across the particle path; an optical detector positioned adjacent the particle path for detecting impingement of the beams of light on individual particles; a desorption laser for generating a beam of desorbing light across the particle path about coaxial with a beam of light produced by one of the tracking lasers; and a controller, responsive to detection of a signal produced by the optical detector, that controls the desorption laser to generate the beam of desorbing light. Additional systems and methods are also disclosed.

Modelling and simulation of particle-particle interaction in a magnetophoretic bio-separation chip

NASA Astrophysics Data System (ADS)

Alam, Manjurul; Golozar, Matin; Darabi, Jeff

2018-04-01

A Lagrangian particle trajectory model is developed to predict the interaction between cell-bead particle complexes and to track their trajectories in a magnetophoretic bio-separation chip. Magnetic flux gradients are simulated in the OpenFOAM CFD software and imported into MATLAB to obtain the trapping lengths and trajectories of the particles. A connector vector is introduced to calculate the interaction force between cell-bead complexes as they flow through a microfluidic device. The interaction force calculations are performed for cases where the connector vector is parallel, perpendicular, and at an angle of 45° with the applied magnetic field. The trajectories of the particles are simulated by solving a system of eight ordinary differential equations using a fourth order Runge-Kutta method. The model is then used to study the effects of geometric positions and angles of the connector vector between the particles as well as the cell size, number of beads per cell, and flow rate on the interaction force and trajectories of the particles. The results show that the interaction forces may be attractive or repulsive, depending on the orientation of the connector vector distance between the particle complexes and the applied magnetic field. When the interaction force is attractive, the particles are observed to merge and trap sooner than a single particle, whereas a repulsive interaction force has little or no effect on the trapping length.

Flow and Jamming of Granular Materials in a Two-dimensional Hopper

NASA Astrophysics Data System (ADS)

Tang, Junyao

Flow in a hopper is both a fertile testing ground for understanding fundamental granular flow rheology and industrially highly relevant. Despite increasing research efforts in this area, a comprehensive physical theory is still lacking for both jamming and flow of granular materials in a hopper. In this work, I have designed a two dimensional (2D) hopper experiment using photoelastic particles (particles' shape: disk or ellipse), with the goal to build a bridge between macroscopic phenomenon of hopper flow and microscopic particle-scale dynamics. Through synchronized data of particle tracking and stress distributions in particles, I have shown differences between my data of the time-averaged velocity/stress profile of 2D hopper flow with previous theoretical predictions. I have also demonstrated the importance of a mechanical stable arch near the opening on controlling hopper flow rheology and suggested a heuristic phase diagram for the hopper flow/jamming transition. Another part of this thesis work is focused on studying the impact of particle shape of particles on hopper flow. By comparing particle-tracking and photoelastic data for ellipses and disks at the appropriate length scale, I have demonstrated an important role for the rotational freedom of elliptical particles in controlling flow rheology through particle tracking and stress analysis. This work has been supported by International Fine Particle Research Institute (IFPRI) .

Atmospheric Neutrinos in Soudan 2

NASA Astrophysics Data System (ADS)

Goodman, M.; Soudan 2 Collaboration

2001-08-01

Neutrino interactions recorded in a 5.1 fiducial kiloton-year exposure of the Soudan-2 iron tracking calorimeter are analyzed for effects of neutrino oscillations. Using contained single track and single shower events, we update our measurement of the atmospheric / ratio-of-ratios and find . Assuming this anomalously low R-value is the result of flavor disappearance viat o oscillation, we select samples of charged current events which offer good resolution, event-by-event, for Ä reconstruction. Oscillation-weighted Monte Carlo events are fitted to these data events using a ¾ function summed over bins of log´Ä µ. The region allowed in the (× Ò¾ ¾ , ¡Ñ¾) plane at 90% CL is obtained using the Feldman-Cousins procedure: 1 DETECTOR; DATA EXPOSURE The Soudan-2 experiment will soon (July 2001) be completing the taking of data using its fine-grained iron tracking calorimeter of total mass 963 tons. This detector images nonrelativistic as well as relativistic charged particles produced in atmospheric neutrino reactions. It has operated underground at a depth of 2100 meters-water-equivalent on level 27 of the Soudan Mine State Park in northern Minnesota. The calorimeter's modular design enabled data-taking to commence in April 1989 when the detector was one quarter of its full size; assembly of the detector was completed during 1993. Data-taking continued with 85% live time, even though dynamite blasting has been underway nearby for the MINOS cavern excavation since Summer 1999. The total data exposure will be 5.8fiducial kiloton-years (kTy). Results presented here are based upon a 5.1 kTy exposure. The tracking calorimeter operates as a slow-drift (0.6 cm/ s) time projection chamber. Its tracking elements are meterlong plastic drift tubes which are placed into the corruga-

Multi-object tracking of human spermatozoa

NASA Astrophysics Data System (ADS)

Sørensen, Lauge; Østergaard, Jakob; Johansen, Peter; de Bruijne, Marleen

2008-03-01

We propose a system for tracking of human spermatozoa in phase-contrast microscopy image sequences. One of the main aims of a computer-aided sperm analysis (CASA) system is to automatically assess sperm quality based on spermatozoa motility variables. In our case, the problem of assessing sperm quality is cast as a multi-object tracking problem, where the objects being tracked are the spermatozoa. The system combines a particle filter and Kalman filters for robust motion estimation of the spermatozoa tracks. Further, the combinatorial aspect of assigning observations to labels in the particle filter is formulated as a linear assignment problem solved using the Hungarian algorithm on a rectangular cost matrix, making the algorithm capable of handling missing or spurious observations. The costs are calculated using hidden Markov models that express the plausibility of an observation being the next position in the track history of the particle labels. Observations are extracted using a scale-space blob detector utilizing the fact that the spermatozoa appear as bright blobs in a phase-contrast microscope. The output of the system is the complete motion track of each of the spermatozoa. Based on these tracks, different CASA motility variables can be computed, for example curvilinear velocity or straight-line velocity. The performance of the system is tested on three different phase-contrast image sequences of varying complexity, both by visual inspection of the estimated spermatozoa tracks and by measuring the mean squared error (MSE) between the estimated spermatozoa tracks and manually annotated tracks, showing good agreement.

Tracking of fluorescence nanoparticles with nanometre resolution in a biological system: assessing local viscosity and microrheology.

PubMed

Marki, Alex; Ermilov, Eugeny; Zakrzewicz, Andreas; Koller, Akos; Secomb, Timothy W; Pries, Axel R

2014-04-01

The aim of the study was to establish a user-friendly approach for single fluorescence particle 3D localization and tracking with nanometre precision in a standard fluorescence microscope using a point spread function (PSF) approach, and to evaluate validity and precision for different analysis methods and optical conditions with particular application to microcirculatory flow dynamics and cell biology. Images of fluorescent particles were obtained with a standard fluorescence microscope equipped with a piezo positioner for the objective. Whole pattern (WP) comparison with a PSF recorded for the specific set-up and measurement of the outermost ring radius (ORR) were used for analysis. Images of fluorescent particles were recorded over a large range (about 7μm) of vertical positions, with and without distortion by overlapping particles as well as in the presence of cultured endothelial cells. For a vertical range of 6.5μm the standard deviation (SD) from the predicted value, indicating validity, was 9.3/8.7 nm (WP/ORR) in the vertical and 8.2/11.7 nm in the horizontal direction. The precision, determined by repeated measurements, was 5.1/3.8 nm in the vertical and 2.9/3.7 nm in the horizontal direction. WP was more robust with respect to underexposure or overlapping images. On the surface of cultured endothelial cells, a layer with 2.5 times increased viscosity and a thickness of about 0.8μm was detected. With a validity in the range of 10 nm and a precision down to about 3-5 nm obtained by standard fluorescent microscopy, the PSF approach offers a valuable tool for a variety of experimental investigations of particle localizations, including the assessment of endothelial cell microenvironment.

A combined CFD-experimental method for developing an erosion equation for both gas-sand and liquid-sand flows

NASA Astrophysics Data System (ADS)

Mansouri, Amir

The surface degradation of equipment due to consecutive impacts of abrasive particles carried by fluid flow is called solid particle erosion. Solid particle erosion occurs in many industries including oil and gas. In order to prevent abrupt failures and costly repairs, it is essential to predict the erosion rate and identify the locations of the equipment that are mostly at risk. Computational Fluid Dynamics (CFD) is a powerful tool for predicting the erosion rate. Erosion prediction using CFD analysis includes three steps: (1) obtaining flow solution, (2) particle tracking and calculating the particle impact speed and angle, and (3) relating the particle impact information to mass loss of material through an erosion equation. Erosion equations are commonly generated using dry impingement jet tests (sand-air), since the particle impact speed and angle are assumed not to deviate from conditions in the jet. However, in slurry flows, a wide range of particle impact speeds and angles are produced in a single slurry jet test with liquid and sand particles. In this study, a novel and combined CFD/experimental method for developing an erosion equation in slurry flows is presented. In this method, a CFD analysis is used to characterize the particle impact speed, angle, and impact rate at specific locations on the test sample. Then, the particle impact data are related to the measured erosion depth to achieve an erosion equation from submerged testing. Traditionally, it was assumed that the erosion equation developed based on gas testing can be used for both gas-sand and liquid-sand flows. The erosion equations developed in this work were implemented in a CFD code, and CFD predictions were validated for various test conditions. It was shown that the erosion equation developed based on slurry tests can significantly improve the local thickness loss prediction in slurry flows. Finally, a generalized erosion equation is proposed which can be used to predict the erosion rate in gas-sand, water-sand and viscous liquid-sand flows with high accuracy. Furthermore, in order to gain a better understanding of the erosion mechanism, a comprehensive experimental study was conducted to investigate the important factors influencing the erosion rate in gas-sand and slurry flows. The wear pattern and total erosion ratio were measured in a direct impingement jet geometry (for both dry impact and submerged impingement jets). The effects of fluid viscosity, abrasive particle size, particle impact speed, jet inclination angle, standoff distance, sand concentration, and exposure time were investigated. Also, the eroded samples were studied with Scanning Electron Microscopy (SEM) to understand the erosion micro-structure. Also, the sand particle impact speed and angle were measured using a Particle Image Velocimetry (PIV) system. The measurements were conducted in two types of erosion testers (gas-solid and liquid-solid impinging jets). The Particle Tracking Velocimetry (PTV) technique was utilized which is capable of tracking individual small particles. Moreover, CFD modeling was performed to predict the particle impact data. Very good agreement between the CFD results and PTV measurements was observed.

Monte Carlo charged-particle tracking and energy deposition on a Lagrangian mesh.

PubMed

Yuan, J; Moses, G A; McKenty, P W

2005-10-01

A Monte Carlo algorithm for alpha particle tracking and energy deposition on a cylindrical computational mesh in a Lagrangian hydrodynamics code used for inertial confinement fusion (ICF) simulations is presented. The straight line approximation is used to follow propagation of "Monte Carlo particles" which represent collections of alpha particles generated from thermonuclear deuterium-tritium (DT) reactions. Energy deposition in the plasma is modeled by the continuous slowing down approximation. The scheme addresses various aspects arising in the coupling of Monte Carlo tracking with Lagrangian hydrodynamics; such as non-orthogonal severely distorted mesh cells, particle relocation on the moving mesh and particle relocation after rezoning. A comparison with the flux-limited multi-group diffusion transport method is presented for a polar direct drive target design for the National Ignition Facility. Simulations show the Monte Carlo transport method predicts about earlier ignition than predicted by the diffusion method, and generates higher hot spot temperature. Nearly linear speed-up is achieved for multi-processor parallel simulations.

Collisional charging of individual submillimeter particles: Using ultrasonic levitation to initiate and track charge transfer

NASA Astrophysics Data System (ADS)

Lee, Victor; James, Nicole M.; Waitukaitis, Scott R.; Jaeger, Heinrich M.

2018-03-01

Electrostatic charging of insulating fine particles can be responsible for numerous phenomena ranging from lightning in volcanic plumes to dust explosions. However, even basic aspects of how fine particles become charged are still unclear. Studying particle charging is challenging because it usually involves the complexities associated with many-particle collisions. To address these issues, we introduce a method based on acoustic levitation, which makes it possible to initiate sequences of repeated collisions of a single submillimeter particle with a flat plate, and to precisely measure the particle charge in situ after each collision. We show that collisional charge transfer between insulators is dependent on the hydrophobicity of the contacting surfaces. We use glass, which we modify by attaching nonpolar molecules to the particle, the plate, or both. We find that hydrophilic surfaces develop significant positive charges after contacting hydrophobic surfaces. Moreover, we demonstrate that charging between a hydrophilic and a hydrophobic surface is suppressed in an acidic environment and enhanced in a basic one. Application of an electric field during each collision is found to modify the charge transfer, again depending on surface hydrophobicity. We discuss these results within the context of contact charging due to ion transfer, and we show that they lend strong support to O H- ions as the charge carriers.

Particle Streak Velocimetry of Supersonic Nozzle Flows

NASA Technical Reports Server (NTRS)

Willits, J. D.; Pourpoint, T. L.

2016-01-01

A novel velocimetry technique to probe the exhaust flow of a laboratory scale combustor is being developed. The technique combines the advantages of standard particle velocimetry techniques and the ultra-fast imaging capabilities of a streak camera to probe high speed flows near continuously with improved spatial and velocity resolution. This "Particle Streak Velocimetry" technique tracks laser illuminated seed particles at up to 236 picosecond temporal resolution allowing time-resolved measurement of one-dimensional flows exceeding 2000 m/s as are found in rocket nozzles and many other applications. Developmental tests with cold nitrogen have been performed to validate and troubleshoot the technique with supersonic flows of much lower velocity and without background noise due to combusting flow. Flow velocities on the order of 500 m/s have been probed with titanium dioxide particles and a continuous-wave laser diode. Single frame images containing multiple streaks are analyzed to find the average slope of all incident particles corresponding to the centerline axial flow velocity. Long term objectives for these tests are correlation of specific impulse to theoretical combustion predictions and direct comparisons between candidate green fuels and the industry standard, monomethylhydrazine, each tested under identical conditions.

A binary link tracker for the BaBar level 1 trigger system

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

Berenyi, A.; Chen, H.K.; Dao, K.

1999-08-01

The BaBar detector at PEP-II will operate in a high-luminosity e{sup +}e{sup {minus}} collider environment near the {Upsilon}(4S) resonance with the primary goal of studying CP violation in the B meson system. In this environment, typical physics events of interest involve multiple charged particles. These events are identified by counting these tracks in a fast first level (Level 1) trigger system, by reconstructing the tracks in real time. For this purpose, a Binary Link Tracker Module (BLTM) was designed and fabricated for the BaBar Level 1 Drift Chamber trigger system. The BLTM is responsible for linking track segments, constructed bymore » the Track Segment Finder Modules (TSFM), into complete tracks. A single BLTM module processes a 360 MBytes/s stream of segment hit data, corresponding to information from the entire Drift Chamber, and implements a fast and robust algorithm that tolerates high hit occupancies as well as local inefficiencies of the Drift Chamber. The algorithms and the necessary control logic of the BLTM were implemented in Field Programmable Gate Arrays (FPGAs), using the VHDL hardware description language. The finished 9U x 400 mm Euro-format board contains roughly 75,000 gates of programmable logic or about 10,000 lines of VHDL code synthesized into five FPGAs.« less

Reduced Noise UV Enhancement of Etch Rates for Nuclear Tracks in CR-39

NASA Astrophysics Data System (ADS)

Sheets, Rebecca; Clarkson, David; Ume, Rubab; Regan, Sean; Sangster, Craig; Padalino, Stephen; McLean, James

2016-10-01

The use of CR-39 plastic as a Solid State Nuclear Track Detector is an effective technique for obtaining data in high-energy particle experiments including inertial confinement fusion. To reveal particle tracks after irradiation, CR-39 is chemically etched in NaOH at 80°C for 6 hours, producing micron-scale signal pits at the nuclear track sites. Using CR-39 irradiated with 5.4 MeV alpha particles and 1.0 MeV protons, we show that exposing the CR-39 to high intensity UV light before etching, with wavelengths between 240 nm and 350 nm, speeds the etch process. Elevated temperatures during UV exposure amplifies this effect, with etch rates up to 50% greater than unprocessed conditions. CR-39 pieces exposed to UV light and heat can also exhibit heightened levels of etch-induced noise (surface features not caused by nuclear particles). By illuminating the CR-39 from the side opposite to the tracks, a similar level of etch enhancement was obtained with little to no noise. The effective wavelength range is reduced, due to strong attenuation of shorter wavelengths. Funded in part by a LLE contract through the DOE.

Track structure in biological models.

PubMed

Curtis, S B

1986-01-01

High-energy heavy ions in the galactic cosmic radiation (HZE particles) may pose a special risk during long term manned space flights outside the sheltering confines of the earth's geomagnetic field. These particles are highly ionizing, and they and their nuclear secondaries can penetrate many centimeters of body tissue. The three dimensional patterns of ionizations they create as they lose energy are referred to as their track structure. Several models of biological action on mammalian cells attempt to treat track structure or related quantities in their formulation. The methods by which they do this are reviewed. The proximity function is introduced in connection with the theory of Dual Radiation Action (DRA). The ion-gamma kill (IGK) model introduces the radial energy-density distribution, which is a smooth function characterizing both the magnitude and extension of a charged particle track. The lethal, potentially lethal (LPL) model introduces lambda, the mean distance between relevant ion clusters or biochemical species along the track. Since very localized energy depositions (within approximately 10 nm) are emphasized, the proximity function as defined in the DRA model is not of utility in characterizing track structure in the LPL formulation.

An Integrated Approach to Indoor and Outdoor Localization

DTIC Science & Technology

2017-04-17

localization estimate, followed by particle filter based tracking. Initial localization is performed using WiFi and image observations. For tracking we...source. A two-step process is proposed that performs an initial localization es-timate, followed by particle filter based t racking. Initial...mapped, it is possible to use them for localization [20, 21, 22]. Haverinen et al. show that these fields could be used with a particle filter to

Image computing techniques to extrapolate data for dust tracking in case of an experimental accident simulation in a nuclear fusion plant.

PubMed

Camplani, M; Malizia, A; Gelfusa, M; Barbato, F; Antonelli, L; Poggi, L A; Ciparisse, J F; Salgado, L; Richetta, M; Gaudio, P

2016-01-01

In this paper, a preliminary shadowgraph-based analysis of dust particles re-suspension due to loss of vacuum accident (LOVA) in ITER-like nuclear fusion reactors has been presented. Dust particles are produced through different mechanisms in nuclear fusion devices, one of the main issues is that dust particles are capable of being re-suspended in case of events such as LOVA. Shadowgraph is based on an expanded collimated beam of light emitted by a laser or a lamp that emits light transversely compared to the flow field direction. In the STARDUST facility, the dust moves in the flow, and it causes variations of refractive index that can be detected by using a CCD camera. The STARDUST fast camera setup allows to detect and to track dust particles moving in the vessel and then to obtain information about the velocity field of dust mobilized. In particular, the acquired images are processed such that per each frame the moving dust particles are detected by applying a background subtraction technique based on the mixture of Gaussian algorithm. The obtained foreground masks are eventually filtered with morphological operations. Finally, a multi-object tracking algorithm is used to track the detected particles along the experiment. For each particle, a Kalman filter-based tracker is applied; the particles dynamic is described by taking into account position, velocity, and acceleration as state variable. The results demonstrate that it is possible to obtain dust particles' velocity field during LOVA by automatically processing the data obtained with the shadowgraph approach.

Image computing techniques to extrapolate data for dust tracking in case of an experimental accident simulation in a nuclear fusion plant

NASA Astrophysics Data System (ADS)

Camplani, M.; Malizia, A.; Gelfusa, M.; Barbato, F.; Antonelli, L.; Poggi, L. A.; Ciparisse, J. F.; Salgado, L.; Richetta, M.; Gaudio, P.

2016-01-01

In this paper, a preliminary shadowgraph-based analysis of dust particles re-suspension due to loss of vacuum accident (LOVA) in ITER-like nuclear fusion reactors has been presented. Dust particles are produced through different mechanisms in nuclear fusion devices, one of the main issues is that dust particles are capable of being re-suspended in case of events such as LOVA. Shadowgraph is based on an expanded collimated beam of light emitted by a laser or a lamp that emits light transversely compared to the flow field direction. In the STARDUST facility, the dust moves in the flow, and it causes variations of refractive index that can be detected by using a CCD camera. The STARDUST fast camera setup allows to detect and to track dust particles moving in the vessel and then to obtain information about the velocity field of dust mobilized. In particular, the acquired images are processed such that per each frame the moving dust particles are detected by applying a background subtraction technique based on the mixture of Gaussian algorithm. The obtained foreground masks are eventually filtered with morphological operations. Finally, a multi-object tracking algorithm is used to track the detected particles along the experiment. For each particle, a Kalman filter-based tracker is applied; the particles dynamic is described by taking into account position, velocity, and acceleration as state variable. The results demonstrate that it is possible to obtain dust particles' velocity field during LOVA by automatically processing the data obtained with the shadowgraph approach.

Directional Track Selection Technique in CR39 SSNTD for lowyield reaction experiments

NASA Astrophysics Data System (ADS)

Ingenito, Francesco; Andreoli, Pierluigi; Batani, Dimitri; Bonasera, Aldo; Boutoux, Guillaume; Burgy, Frederic; Cipriani, Mattia; Consoli, Fabrizio; Cristofari, Giuseppe; De Angelis, Riccardo; Di Giorgio, Giorgio; Ducret, Jean Eric; Giulietti, Danilo; Jakubowska, Katarzyna

2018-01-01

There is a great interest in the study of p-11B aneutronic nuclear fusion reactions, both for energy production and for determination of fusion cross-sections at low energies. In this context we performed experiments at CELIA in which energetic protons, accelerated by the laser ECLIPSE, were directed toward a solid Boron target. Because of the small cross-sections at these energies the number of expected reactions is low. CR39 Solid-State Nuclear Track Detectors (SSNTD) were used to detect the alpha particles produced. Because of the low expected yield, it is difficult to discriminate the tracks due to true fusion products from those due to natural background in the CR39. To this purpose we developed a methodology of particle recognition according to their direction with respect to the detector normal, able to determine the position of their source. We applied this to the specific experiment geometry, so to select from all the tracks those due to particles coming from the region of interaction between accelerated protons and solid boron target. This technique can be of great help on the analysis of SSNTD in experiments with low yield reactions, but can be also generally applied to any experiment where particles reach the track detector with known directions, and for example to improve the detection limit of particle spectrometers using CR39.

Quantifying non-ergodic dynamics of force-free granular gases.

PubMed

Bodrova, Anna; Chechkin, Aleksei V; Cherstvy, Andrey G; Metzler, Ralf

2015-09-14

Brownian motion is ergodic in the Boltzmann-Khinchin sense that long time averages of physical observables such as the mean squared displacement provide the same information as the corresponding ensemble average, even at out-of-equilibrium conditions. This property is the fundamental prerequisite for single particle tracking and its analysis in simple liquids. We study analytically and by event-driven molecular dynamics simulations the dynamics of force-free cooling granular gases and reveal a violation of ergodicity in this Boltzmann-Khinchin sense as well as distinct ageing of the system. Such granular gases comprise materials such as dilute gases of stones, sand, various types of powders, or large molecules, and their mixtures are ubiquitous in Nature and technology, in particular in Space. We treat-depending on the physical-chemical properties of the inter-particle interaction upon their pair collisions-both a constant and a velocity-dependent (viscoelastic) restitution coefficient ε. Moreover we compare the granular gas dynamics with an effective single particle stochastic model based on an underdamped Langevin equation with time dependent diffusivity. We find that both models share the same behaviour of the ensemble mean squared displacement (MSD) and the velocity correlations in the limit of weak dissipation. Qualitatively, the reported non-ergodic behaviour is generic for granular gases with any realistic dependence of ε on the impact velocity of particles.

Particle tracking approach for transport in three-dimensional discrete fracture networks: Particle tracking in 3-D DFNs

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

Makedonska, Nataliia; Painter, Scott L.; Bui, Quan M.

The discrete fracture network (DFN) model is a method to mimic discrete pathways for fluid flow through a fractured low-permeable rock mass, and may be combined with particle tracking simulations to address solute transport. However, experience has shown that it is challenging to obtain accurate transport results in three-dimensional DFNs because of the high computational burden and difficulty in constructing a high-quality unstructured computational mesh on simulated fractures. We present a new particle tracking capability, which is adapted to control volume (Voronoi polygons) flow solutions on unstructured grids (Delaunay triangulations) on three-dimensional DFNs. The locally mass-conserving finite-volume approach eliminates massmore » balance-related problems during particle tracking. The scalar fluxes calculated for each control volume face by the flow solver are used to reconstruct a Darcy velocity at each control volume centroid. The groundwater velocities can then be continuously interpolated to any point in the domain of interest. The control volumes at fracture intersections are split into four pieces, and the velocity is reconstructed independently on each piece, which results in multiple groundwater velocities at the intersection, one for each fracture on each side of the intersection line. This technique enables detailed particle transport representation through a complex DFN structure. Verified for small DFNs, the new simulation capability enables numerical experiments on advective transport in large DFNs to be performed. As a result, we demonstrate this particle transport approach on a DFN model using parameters similar to those of crystalline rock at a proposed geologic repository for spent nuclear fuel in Forsmark, Sweden.« less

Particle tracking approach for transport in three-dimensional discrete fracture networks: Particle tracking in 3-D DFNs

DOE PAGES

Makedonska, Nataliia; Painter, Scott L.; Bui, Quan M.; ...

2015-09-16

The discrete fracture network (DFN) model is a method to mimic discrete pathways for fluid flow through a fractured low-permeable rock mass, and may be combined with particle tracking simulations to address solute transport. However, experience has shown that it is challenging to obtain accurate transport results in three-dimensional DFNs because of the high computational burden and difficulty in constructing a high-quality unstructured computational mesh on simulated fractures. We present a new particle tracking capability, which is adapted to control volume (Voronoi polygons) flow solutions on unstructured grids (Delaunay triangulations) on three-dimensional DFNs. The locally mass-conserving finite-volume approach eliminates massmore » balance-related problems during particle tracking. The scalar fluxes calculated for each control volume face by the flow solver are used to reconstruct a Darcy velocity at each control volume centroid. The groundwater velocities can then be continuously interpolated to any point in the domain of interest. The control volumes at fracture intersections are split into four pieces, and the velocity is reconstructed independently on each piece, which results in multiple groundwater velocities at the intersection, one for each fracture on each side of the intersection line. This technique enables detailed particle transport representation through a complex DFN structure. Verified for small DFNs, the new simulation capability enables numerical experiments on advective transport in large DFNs to be performed. As a result, we demonstrate this particle transport approach on a DFN model using parameters similar to those of crystalline rock at a proposed geologic repository for spent nuclear fuel in Forsmark, Sweden.« less

The frequency-dependent response of single aerosol particles to vapour phase oscillations and its application in measuring diffusion coefficients

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

Preston, Thomas C.; Davies, James F.; Wilson, Kevin R.

A new method for measuring diffusion in the condensed phase of single aerosol particles is proposed and demonstrated. The technique is based on the frequency-dependent response of a binary particle to oscillations in the vapour phase of one of its chemical components. Here, we discuss how this physical situation allows for what would typically be a non-linear boundary value problem to be approximately reduced to a linear boundary value problem. For the case of aqueous aerosol particles, we investigate the accuracy of the closed-form analytical solution to this linear problem through a comparison with the numerical solution of the fullmore » problem. Then, using experimentally measured whispering gallery modes to track the frequency-dependent response of aqueous particles to relative humidity oscillations, we determine diffusion coefficients as a function of water activity. The measured diffusion coefficients are compared to previously reported values found using the two common experiments: (i) the analysis of the sorption/desorption of water from a particle after a step-wise change to the surrounding relative humidity and (ii) the isotopic exchange of water between a particle and the vapour phase. The technique presented here has two main strengths: first, when compared to the sorption/desorption experiment, it does not require the numerical evaluation of a boundary value problem during the fitting process as a closed-form expression is available. Second, when compared to the isotope exchange experiment, it does not require the use of labeled molecules. Therefore, the frequency-dependent experiment retains the advantages of these two commonly used methods but does not suffer from their drawbacks.« less

The frequency-dependent response of single aerosol particles to vapour phase oscillations and its application in measuring diffusion coefficients

DOE PAGES

Preston, Thomas C.; Davies, James F.; Wilson, Kevin R.

2017-01-13

A new method for measuring diffusion in the condensed phase of single aerosol particles is proposed and demonstrated. The technique is based on the frequency-dependent response of a binary particle to oscillations in the vapour phase of one of its chemical components. Here, we discuss how this physical situation allows for what would typically be a non-linear boundary value problem to be approximately reduced to a linear boundary value problem. For the case of aqueous aerosol particles, we investigate the accuracy of the closed-form analytical solution to this linear problem through a comparison with the numerical solution of the fullmore » problem. Then, using experimentally measured whispering gallery modes to track the frequency-dependent response of aqueous particles to relative humidity oscillations, we determine diffusion coefficients as a function of water activity. The measured diffusion coefficients are compared to previously reported values found using the two common experiments: (i) the analysis of the sorption/desorption of water from a particle after a step-wise change to the surrounding relative humidity and (ii) the isotopic exchange of water between a particle and the vapour phase. The technique presented here has two main strengths: first, when compared to the sorption/desorption experiment, it does not require the numerical evaluation of a boundary value problem during the fitting process as a closed-form expression is available. Second, when compared to the isotope exchange experiment, it does not require the use of labeled molecules. Therefore, the frequency-dependent experiment retains the advantages of these two commonly used methods but does not suffer from their drawbacks.« less

Nanodosimetric track structure in homogeneous extended beams.

PubMed

Conte, V; Moro, D; Colautti, P; Grosswendt, B

2015-09-01

Physical aspects of particle track structure are important in determining the induction of clustered damage in relevant subcellular structures like the DNA and higher-order genomic structures. The direct measurement of track-structure properties of ionising radiation is feasible today by counting the number of ionisations produced inside a small gas volume. In particular, the so-called track-nanodosimeter, installed at the TANDEM-ALPI accelerator complex of LNL, measures ionisation cluster-size distributions in a simulated subcellular structure of dimensions 20 nm, corresponding approximately to the diameter of the chromatin fibre. The target volume is irradiated by pencil beams of primary particles passing at specified impact parameter. To directly relate these measured track-structure data to radiobiological measurements performed in broad homogeneous particle beams, these data can be integrated over the impact parameter. This procedure was successfully applied to 240 MeV carbon ions and compared with Monte Carlo simulations for extended fields. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

2013 R&D 100 Award: DNATrax could revolutionize air quality detection and tracking

ScienceCinema

Farquar, George

2018-01-16

A team of LLNL scientists and engineers has developed a safe and versatile material, known as DNA Tagged Reagents for Aerosol Experiments (DNATrax), that can be used to reliably and rapidly diagnose airflow patterns and problems in both indoor and outdoor venues. Until DNATrax particles were developed, no rapid or safe way existed to validate air transport models with realistic particles in the range of 1-10 microns. Successful DNATrax testing was conducted at the Pentagon in November 2012 in conjunction with the Pentagon Force Protection Agency. This study enhanced the team's understanding of indoor ventilation environments created by heating, ventilation and air conditioning (HVAC) systems. DNATrax are particles comprised of sugar and synthetic DNA that serve as a bar code for the particle. The potential for creating unique bar-coded particles is virtually unlimited, thus allowing for simultaneous and repeated releases, which dramatically reduces the costs associated with conducting tests for contaminants. Among the applications for the new material are indoor air quality detection, for homes, offices, ships and airplanes; urban particulate tracking, for subway stations, train stations, and convention centers; environmental release tracking; and oil and gas uses, including fracking, to better track fluid flow.

2013 R&D 100 Award: DNATrax could revolutionize air quality detection and tracking

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

Farquar, George

A team of LLNL scientists and engineers has developed a safe and versatile material, known as DNA Tagged Reagents for Aerosol Experiments (DNATrax), that can be used to reliably and rapidly diagnose airflow patterns and problems in both indoor and outdoor venues. Until DNATrax particles were developed, no rapid or safe way existed to validate air transport models with realistic particles in the range of 1-10 microns. Successful DNATrax testing was conducted at the Pentagon in November 2012 in conjunction with the Pentagon Force Protection Agency. This study enhanced the team's understanding of indoor ventilation environments created by heating, ventilationmore » and air conditioning (HVAC) systems. DNATrax are particles comprised of sugar and synthetic DNA that serve as a bar code for the particle. The potential for creating unique bar-coded particles is virtually unlimited, thus allowing for simultaneous and repeated releases, which dramatically reduces the costs associated with conducting tests for contaminants. Among the applications for the new material are indoor air quality detection, for homes, offices, ships and airplanes; urban particulate tracking, for subway stations, train stations, and convention centers; environmental release tracking; and oil and gas uses, including fracking, to better track fluid flow.« less

A GEM-TPC in twin configuration for the Super-FRS tracking of heavy ions at FAIR

NASA Astrophysics Data System (ADS)

García, F.; Grahn, T.; Hoffmann, J.; Jokinen, A.; Kaya, C.; Kunkel, J.; Rinta-Antila, S.; Risch, H.; Rusanov, I.; Schmidt, C. J.; Simon, H.; Simons, C.; Turpeinen, R.; Voss, B.; Äystö, J.; Winkler, M.

2018-03-01

The GEM-TPC described herein will be part of the standard beam-diagnostics equipment of the Super-FRS. This chamber will provide tracking information for particle identification at rates up to 1 MHz on an event-by-event basis. The key requirements of operation for these chambers are: close to 100% tracking efficiency under conditions of high counting rate, spatial resolution below 1 mm and a superb large dynamic range covering projectiles from Z = 1 up to Z = 92. The current prototype consists of two GEM-TPCs inside a single vessel, which are operating independently and have electrical drift fields in opposite directions. The twin configuration is done by flipping one of the GEM-TPCs on the middle plane with respect to the second one. In order to put this development in context, the evolution of previous prototypes will be described and its performances discussed. Finally, this chamber was tested at the University of Jyväskylä accelerator with proton projectiles and at GSI with Uranium, Xenon, fragments and Carbon beams. The results obtained have shown a position resolution between 120 to 300 μm at moderate counting rate under conditions of full tracking efficiency.

Measurement of nanoparticle size, suspension polydispersity, and stability using near-field optical trapping and light scattering (Conference Presentation)

NASA Astrophysics Data System (ADS)

Schein, Perry; O'Dell, Dakota; Erickson, David

2017-02-01

Nanoparticles are becoming ubiquitous in applications including diagnostic assays, drug delivery and therapeutics. However, there remain challenges in the quality control of these products. Here we present methods for the orthogonal measurement of these parameters by tracking the motion of the nanoparticle in all three special dimensions as it interacts with an optical waveguide. These simultaneous measurements from a single particle basis address some of the gaps left by current measurement technologies such as nanoparticle tracking analysis, ζ-potential measurements, and absorption spectroscopy. As nanoparticles suspended in a microfluidic channel interact with the evanescent field of an optical waveguide, they experience forces and resulting motion in three dimensions: along the propagation axis of the waveguide (x-direction) they are propelled by the optical forces, parallel to the plane of the waveguide and perpendicular to the optical propagation axis (y-direction) they experience an optical gradient force generated from the waveguide mode profile which confines them in a harmonic potential well, and normal to the surface of the waveguide they experience an exponential downward optical force balanced by the surface interactions that confines the particle in an asymmetric well. Building on our Nanophotonic Force Microscopy technique, in this talk we will explain how to simultaneously use the motion in the y-direction to estimate the size of the particle, the comparative velocity in the x-direction to measure the polydispersity of a particle population, and the motion in the z-direction to measure the potential energy landscape of the interaction, providing insight into the colloidal stability.

Enhanced compressed sensing for visual target tracking in wireless visual sensor networks

NASA Astrophysics Data System (ADS)

Qiang, Guo

2017-11-01

Moving object tracking in wireless sensor networks (WSNs) has been widely applied in various fields. Designing low-power WSNs for the limited resources of the sensor, such as energy limitation, energy restriction, and bandwidth constraints, is of high priority. However, most existing works focus on only single conflicting optimization criteria. An efficient compressive sensing technique based on a customized memory gradient pursuit algorithm with early termination in WSNs is presented, which strikes compelling trade-offs among energy dissipation for wireless transmission, certain types of bandwidth, and minimum storage. Then, the proposed approach adopts an unscented particle filter to predict the location of the target. The experimental results with a theoretical analysis demonstrate the substantially superior effectiveness of the proposed model and framework in regard to the energy and speed under the resource limitation of a visual sensor node.

Rotational dynamics of cargos at pauses during axonal transport.

PubMed

Gu, Yan; Sun, Wei; Wang, Gufeng; Jeftinija, Ksenija; Jeftinija, Srdija; Fang, Ning

2012-01-01

Direct visualization of axonal transport in live neurons is essential for our understanding of the neuronal functions and the working mechanisms of microtubule-based motor proteins. Here we use the high-speed single particle orientation and rotational tracking technique to directly visualize the rotational dynamics of cargos in both active directional transport and pausing stages of axonal transport, with a temporal resolution of 2 ms. Both long and short pauses are imaged, and the correlations between the pause duration, the rotational behaviour of the cargo at the pause, and the moving direction after the pause are established. Furthermore, the rotational dynamics leading to switching tracks are visualized in detail. These first-time observations of cargo's rotational dynamics provide new insights on how kinesin and dynein motors take the cargo through the alternating stages of active directional transport and pause.

Track-before-detect labeled multi-bernoulli particle filter with label switching

NASA Astrophysics Data System (ADS)

Garcia-Fernandez, Angel F.

2016-10-01

This paper presents a multitarget tracking particle filter (PF) for general track-before-detect measurement models. The PF is presented in the random finite set framework and uses a labelled multi-Bernoulli approximation. We also present a label switching improvement algorithm based on Markov chain Monte Carlo that is expected to increase filter performance if targets get in close proximity for a sufficiently long time. The PF is tested in two challenging numerical examples.

Advective transport observations with MODPATH-OBS--documentation of the MODPATH observation process

USGS Publications Warehouse

Hanson, R.T.; Kauffman, L.K.; Hill, M.C.; Dickinson, J.E.; Mehl, S.W.

2013-01-01

The MODPATH-OBS computer program described in this report is designed to calculate simulated equivalents for observations related to advective groundwater transport that can be represented in a quantitative way by using simulated particle-tracking data. The simulated equivalents supported by MODPATH-OBS are (1) distance from a source location at a defined time, or proximity to an observed location; (2) time of travel from an initial location to defined locations, areas, or volumes of the simulated system; (3) concentrations used to simulate groundwater age; and (4) percentages of water derived from contributing source areas. Although particle tracking only simulates the advective component of conservative transport, effects of non-conservative processes such as retardation can be approximated through manipulation of the effective-porosity value used to calculate velocity based on the properties of selected conservative tracers. This program can also account for simple decay or production, but it cannot account for diffusion. Dispersion can be represented through direct simulation of subsurface heterogeneity and the use of many particles. MODPATH-OBS acts as a postprocessor to MODPATH, so that the sequence of model runs generally required is MODFLOW, MODPATH, and MODPATH-OBS. The version of MODFLOW and MODPATH that support the version of MODPATH-OBS presented in this report are MODFLOW-2005 or MODFLOW-LGR, and MODPATH-LGR. MODFLOW-LGR is derived from MODFLOW-2005, MODPATH 5, and MODPATH 6 and supports local grid refinement. MODPATH-LGR is derived from MODPATH 5. It supports the forward and backward tracking of particles through locally refined grids and provides the output needed for MODPATH_OBS. For a single grid and no observations, MODPATH-LGR results are equivalent to MODPATH 5. MODPATH-LGR and MODPATH-OBS simulations can use nearly all of the capabilities of MODFLOW-2005 and MODFLOW-LGR; for example, simulations may be steady-state, transient, or a combination. Though the program name MODPATH-OBS specifically refers to observations, the program also can be used to calculate model prediction of observations. MODPATH-OBS is primarily intended for use with separate programs that conduct sensitivity analysis, data needs assessment, parameter estimation, and uncertainty analysis, such as UCODE_2005, and PEST. In many circumstances, refined grids in selected parts of a model are important to simulated hydraulics, detailed inflows and outflows, or other system characteristics. MODFLOW-LGR and MODPATH-LGR support accurate local grid refinement in which both mass (flows) and energy (head) are conserved across the local grid boundary. MODPATH-OBS is designed to take advantage of these capabilities. For example, particles tracked between a pumping well and a nearby stream, which are simulated poorly if a river and well are located in a single large grid cell, can be simulated with improved accuracy using a locally refined grid in MODFLOW-LGR, MODPATH-LGR, and MODPATH-OBS. The locally-refined-grid approach can provide more accurate simulated equivalents to observed transport between the well and the river. The documentation presented here includes a brief discussion of previous work, description of the methods, and detailed descriptions of the required input files and how the output files are typically used.

Calibrations for Charged Particle Tracking with the GlueX Detector

NASA Astrophysics Data System (ADS)

Staib, Michael; GlueX Collaboration

2015-10-01

Two gas detectors comprise the tracking system for the GlueX experiment, the Central Drift Chamber (CDC) and the Forward Drift Chamber (FDC). The CDC is a cylindrical straw-tube detector covering polar angles between 6° and 168°, delivering spatial resolution of ~150 μm. The FDC is a Cathode Strip Chamber consisting of four packages, each with six alternating layers of anode wires and cathode strips. The FDC is designed to track forward-going charged particles with polar angles between 1° and 20° with a spatial resolution of ~200 μm. Both tracking detectors record timing information and energy loss measurements useful for particle identification. During Fall 2014 and Spring 2015, the first photon beam was delivered on target for commissioning of the GlueX detector in Hall-D at Jefferson Lab. These data are currently being used in a large effort to calibrate the individual detector subsystems to achieve design performance. Methods and results for calibrations of each of the tracking detectors are presented. Techniques for alignment of the tracking system using a combination of cosmic rays and beam data is discussed. Finally, some early results of physics measurements including charged final-state particles are presented. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract DE-AC05-06OR23177.

A FPGA-based Cluster Finder for CMOS Monolithic Active Pixel Sensors of the MIMOSA-26 Family

NASA Astrophysics Data System (ADS)

Li, Qiyan; Amar-Youcef, S.; Doering, D.; Deveaux, M.; Fröhlich, I.; Koziel, M.; Krebs, E.; Linnik, B.; Michel, J.; Milanovic, B.; Müntz, C.; Stroth, J.; Tischler, T.

2014-06-01

CMOS Monolithic Active Pixel Sensors (MAPS) demonstrated excellent performances in the field of charged particle tracking. Among their strong points are an single point resolution few μm, a light material budget of 0.05% X0 in combination with a good radiation tolerance and high rate capability. Those features make the sensors a valuable technology for vertex detectors of various experiments in heavy ion and particle physics. To reduce the load on the event builders and future mass storage systems, we have developed algorithms suited for preprocessing and reducing the data streams generated by the MAPS. This real-time processing employs remaining free resources of the FPGAs of the readout controllers of the detector and complements the on-chip data reduction circuits of the MAPS.

SIMULATIONS OF BOOSTER INJECTION EFFICIENCY FOR THE APS-UPGRADE

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

Calvey, J.; Borland, M.; Harkay, K.

2017-06-25

The APS-Upgrade will require the injector chain to provide high single bunch charge for swap-out injection. One possible limiting factor to achieving this is an observed reduction of injection efficiency into the booster synchrotron at high charge. We have simulated booster injection using the particle tracking code elegant, including a model for the booster impedance and beam loading in the RF cavities. The simulations point to two possible causes for reduced efficiency: energy oscillations leading to losses at high dispersion locations, and a vertical beam size blowup caused by ions in the Particle Accumulator Ring. We also show that themore » efficiency is much higher in an alternate booster lattice with smaller vertical beta function and zero dispersion in the straight sections.« less

Silica encapsulation of fluorescent nanodiamonds for colloidal stability and facile surface functionalization.

PubMed

Bumb, Ambika; Sarkar, Susanta K; Billington, Neil; Brechbiel, Martin W; Neuman, Keir C

2013-05-29

Fluorescent nanodiamonds (FNDs) emit in the near-IR and do not photobleach or photoblink. These properties make FNDs better suited for numerous imaging applications compared with commonly used fluorescence agents such as organic dyes and quantum dots. However, nanodiamonds do not form stable suspensions in aqueous buffer, are prone to aggregation, and are difficult to functionalize. Here we present a method for encapsulating nanodiamonds with silica using an innovative liposome-based encapsulation process that renders the particle surface biocompatible, stable, and readily functionalized through routine linking chemistries. Furthermore, the method selects for a desired particle size and produces a monodisperse agent. We attached biotin to the silica-coated FNDs and tracked the three-dimensional motion of a biotinylated FND tethered by a single DNA molecule with high spatial and temporal resolution.

Special technical services for investigation of light flash phenomena

NASA Technical Reports Server (NTRS)

1973-01-01

Details are presented of an investigation aimed at an explanation of the phenomenon of light flashes observed by Apollo crew members. The various theories considered include: penetration of the eye by cosmic particles resulting in retinal stimulation; production of phosphenes or sensations of light through ionization or excitation; appearance of heavily ionized single tracks misinterpreted as light flashes; Cerenkov radiation; and direct excitation of neural tissue by penetrating cosmic rays. It is concluded that the latter two theories are the likeliest mechanisms for the development of a definitive explanation.

The Impacts of Dust Storm Particles on Human Lung Cells - an Analysis at the Single Cell Level

NASA Astrophysics Data System (ADS)

Ardon-Dryer, K.; Mock, C.; Reyes, J.; Lahav, G.

2017-12-01

Aerosols particles (Natural and anthropogenic) are a key component of our atmosphere, their presence defines air quality levels and they can affect our health. Small particles penetrate into our lungs and this exposure can cause our lung cells to stress and in some cases leads to the death of the cells and to inflammation. During dust storm events there is an increase in particle concentration, many of them are breathable particles that can penetrate deep into our lungs. Exposure to dust particles can lead to respiratory problems, particularly for people with asthma. Therefore, during and after a dust storm event the number of people who are hospitalized with inflammation and respiratory problems increase. However, the exact mechanism that causes these health problems is still unclear. In this project, we are investigating the impacts that dust storm particles from different sources and of different concentrations (doses) have on human lung cells, performing a new and unique analysis at the single cell level. To accomplish this, each individual lung cell is continuously tracked after being exposed to dust particles. We monitor the behavior of the cell over time, identify the cells time of death and type of death (e.g. cell explosion). With this analysis, we can quantify cell death as a function of dust concertation (doses); to our surprise, an increase in cells death was not observed only as a function of an increase of dust concertation. In addition, we noticed that the way particles come in contact with cells, by sticking to or being engulfed by, and the interaction duration has an effect; cells that interact with dust particles for a longer period died earlier compared to cells with a shorter interaction period. These findings will help us to better understand the health related consequences of exposure to dust storm events and serve as a baseline for when evaluating other aerosol.

Registration procedure for spatial correlation of physical energy deposition of particle irradiation and cellular response utilizing cell-fluorescent ion track hybrid detectors

NASA Astrophysics Data System (ADS)

Niklas, M.; Zimmermann, F.; Schlegel, J.; Schwager, C.; Debus, J.; Jäkel, O.; Abdollahi, A.; Greilich, S.

2016-09-01

The hybrid technology cell-fluorescent ion track hybrid detector (Cell-Fit-HD) enables the investigation of radiation-related cellular events along single ion tracks on the subcellular scale in clinical ion beams. The Cell-Fit-HD comprises a fluorescent nuclear track detector (FNTD, the physical compartment), a device for individual particle detection and a substrate for viable cell-coating, i.e. the biological compartment. To date both compartments have been imaged sequentially in situ by confocal laser scanning microscopy (CLSM). This is yet in conflict with a functional read-out of the Cell-Fit-HD utilizing a fast live-cell imaging of the biological compartment with low phototoxicity on greater time scales. The read-out of the biological from the physical compartment was uncoupled. A read-out procedure was developed to image the cell layer by conventional widefield microscopy whereas the FNTD was imaged by CLSM. Point mapping registration of the confocal and widefield imaging data was performed. Non-fluorescent crystal defects (spinels) visible in both read-outs were used as control point pairs. The accuracy achieved was on the sub-µm scale. The read-out procedure by widefield microscopy does not impair the unique ability of spatial correlation by the Cell-Fit-HD. The uncoupling will enlarge the application potential of the hybrid technology significantly. The registration allows for an ultimate correlation of microscopic physical beam parameters and cell kinetics on greater time scales. The method reported herein will be instrumental for the introduction of a novel generation of compact detectors facilitating biodosimetric research towards high-throughput analysis.

The Impact of Ship-Produced Aerosols on the Microstructure and Albedo of Warm Marine Stratocumulus Clouds: A Test of MAST Hypotheses 1i and 1ii.

NASA Astrophysics Data System (ADS)

Durkee, P. A.; Noone, K. J.; Ferek, R. J.; Johnson, D. W.; Taylor, J. P.; Garrett, T. J.; Hobbs, P. V.; Hudson, J. G.; Bretherton, C. S.; Innis, G.; Frick, G. M.; Hoppel, W. A.; O'Dowd, C. D.; Russell, L. M.; Gasparovic, R.; Nielsen, K. E.; Tessmer, S. A.; Öström, E.;  Osborne, S. R.;  Flagan, R. C.;  Seinfeld, J. H.;  Rand, H.

2000-08-01

Anomalously high reflectivity tracks in stratus and stratocumulus sheets associated with ships (known as ship tracks) are commonly seen in visible and near-infrared satellite imagery. Until now there have been only a limited number of in situ measurements made in ship tracks. The Monterey Area Ship Track (MAST) experiment, which was conducted off the coast of California in June 1994, provided a substantial dataset on ship emissions and their effects on boundary layer clouds. Several platforms, including the University of Washington C-131A aircraft, the Meteorological Research Flight C-130 aircraft, the National Aeronautics and Space Administration ER-2 aircraft, the Naval Research Laboratory airship, the Research Vessel Glorita, and dedicated U.S. Navy ships, participated in MAST in order to study processes governing the formation and maintenance of ship tracks.This paper tests the hypotheses that the cloud microphysical changes that produce ship tracks are due to (a) particulate emission from the ship's stack and/or (b) sea-salt particles from the ship's wake. It was found that ships powered by diesel propulsion units that emitted high concentrations of aerosols in the accumulation mode produced ship tracks. Ships that produced few particles (such as nuclear ships), or ships that produced high concentrations of particles but at sizes too small to be activated as cloud drops in typical stratocumulus (such as gas turbine and some steam-powered ships), did not produce ship tracks. Statistics and case studies, combined with model simulations, show that provided a cloud layer is susceptible to an aerosol perturbation, and the atmospheric stability enables aerosol to be mixed throughout the boundary layer, the direct emissions of cloud condensation nuclei from the stack of a diesel-powered ship is the most likely, if not the only, cause of the formation of ship tracks. There was no evidence that salt particles from ship wakes cause ship tracks.

Rejecting Non-MIP-Like Tracks using Boosted Decision Trees with the T2K Pi-Zero Subdetector

NASA Astrophysics Data System (ADS)

Hogan, Matthew; Schwehr, Jacklyn; Cherdack, Daniel; Wilson, Robert; T2K Collaboration

2016-03-01

Tokai-to-Kamioka (T2K) is a long-baseline neutrino experiment with a narrow band energy spectrum peaked at 600 MeV. The Pi-Zero detector (PØD) is a plastic scintillator-based detector located in the off-axis near detector complex 280 meters from the beam origin. It is designed to constrain neutral-current induced π0 production background at the far detector using the water target which is interleaved between scintillator layers. A PØD-based measurement of charged-current (CC) single charged pion (1π+) production on water is being developed which will have expanded phase space coverage as compared to the previous analysis. The signal channel for this analysis, which for T2K is dominated by Δ production, is defined as events that produce a single muon, single charged pion, and any number of nucleons in the final state. The analysis will employ machine learning algorithms to enhance CC1π+ selection by studying topological observables that characterize signal well. Important observables for this analysis are those that discriminate a minimum ionizing particle (MIP) like a muon or pion from a proton at the T2K energies. This work describes the development of a discriminator using Boosted Decision Trees to reject non-MIP-like PØD tracks.

Dissecting non-coding RNA mechanisms in cellulo by single-molecule high-resolution localization and counting

PubMed Central

Pitchiaya, Sethuramasundaram; Krishnan, Vishalakshi; Custer, Thomas C.; Walter, Nils G.

2013-01-01

Non-coding RNAs (ncRNAs) recently were discovered to outnumber their protein-coding counterparts, yet their diverse functions are still poorly understood. Here we report on a method for the intracellular Single-molecule High Resolution Localization and Counting (iSHiRLoC) of microRNAs (miRNAs), a conserved, ubiquitous class of regulatory ncRNAs that controls the expression of over 60% of all mammalian protein coding genes post-transcriptionally, by a mechanism shrouded by seemingly contradictory observations. We present protocols to execute single particle tracking (SPT) and single-molecule counting of functional microinjected, fluorophore-labeled miRNAs and thereby extract diffusion coefficients and molecular stoichiometries of micro-ribonucleoprotein (miRNP) complexes from living and fixed cells, respectively. This probing of miRNAs at the single molecule level sheds new light on the intracellular assembly/disassembly of miRNPs, thus beginning to unravel the dynamic nature of this important gene regulatory pathway and facilitating the development of a parsimonious model for their obscured mechanism of action. PMID:23820309

Stochastic four-way coupling of gas-solid flows for Large Eddy Simulations

NASA Astrophysics Data System (ADS)

Curran, Thomas; Denner, Fabian; van Wachem, Berend

2017-11-01

The interaction of solid particles with turbulence has for long been a topic of interest for predicting the behavior of industrially relevant flows. For the turbulent fluid phase, Large Eddy Simulation (LES) methods are widely used for their low computational cost, leaving only the sub-grid scales (SGS) of turbulence to be modelled. Although LES has seen great success in predicting the behavior of turbulent single-phase flows, the development of LES for turbulent gas-solid flows is still in its infancy. This contribution aims at constructing a model to describe the four-way coupling of particles in an LES framework, by considering the role particles play in the transport of turbulent kinetic energy across the scales. Firstly, a stochastic model reconstructing the sub-grid velocities for the particle tracking is presented. Secondly, to solve particle-particle interaction, most models involve a deterministic treatment of the collisions. We finally introduce a stochastic model for estimating the collision probability. All results are validated against fully resolved DNS-DPS simulations. The final goal of this contribution is to propose a global stochastic method adapted to two-phase LES simulation where the number of particles considered can be significantly increased. Financial support from PetroBras is gratefully acknowledged.

SimTrack: A compact c++ code for particle orbit and spin tracking in accelerators

DOE PAGES

Luo, Yun

2015-08-29

SimTrack is a compact c++ code of 6-d symplectic element-by-element particle tracking in accelerators originally designed for head-on beam–beam compensation simulation studies in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. It provides a 6-d symplectic orbit tracking with the 4th order symplectic integration for magnet elements and the 6-d symplectic synchro-beam map for beam–beam interaction. Since its inception in 2009, SimTrack has been intensively used for dynamic aperture calculations with beam–beam interaction for RHIC. Recently, proton spin tracking and electron energy loss due to synchrotron radiation were added. In this article, I will present the code architecture,more » physics models, and some selected examples of its applications to RHIC and a future electron-ion collider design eRHIC.« less

SimTrack: A compact c++ library for particle orbit and spin tracking in accelerators

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

Luo, Yun

2015-06-24

SimTrack is a compact c++ library of 6-d symplectic element-by-element particle tracking in accelerators originally designed for head-on beam-beam compensation simulation studies in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. It provides a 6-d symplectic orbit tracking with the 4th order symplectic integration for magnet elements and the 6-d symplectic synchro-beam map for beam-beam interaction. Since its inception in 2009, SimTrack has been intensively used for dynamic aperture calculations with beam-beam interaction for RHIC. Recently, proton spin tracking and electron energy loss due to synchrotron radiation were added. In this article, I will present the code architecture,more » physics models, and some selected examples of its applications to RHIC and a future electron-ion collider design eRHIC.« less

Fish tracking by combining motion based segmentation and particle filtering

NASA Astrophysics Data System (ADS)

Bichot, E.; Mascarilla, L.; Courtellemont, P.

2006-01-01

In this paper, we suggest a new importance sampling scheme to improve a particle filtering based tracking process. This scheme relies on exploitation of motion segmentation. More precisely, we propagate hypotheses from particle filtering to blobs of similar motion to target. Hence, search is driven toward regions of interest in the state space and prediction is more accurate. We also propose to exploit segmentation to update target model. Once the moving target has been identified, a representative model is learnt from its spatial support. We refer to this model in the correction step of the tracking process. The importance sampling scheme and the strategy to update target model improve the performance of particle filtering in complex situations of occlusions compared to a simple Bootstrap approach as shown by our experiments on real fish tank sequences.

High resolution particle tracking method by suppressing the wavefront aberrations

NASA Astrophysics Data System (ADS)

Chang, Xinyu; Yang, Yuan; Kou, Li; Jin, Lei; Lu, Junsheng; Hu, Xiaodong

2018-01-01

Digital in-line holographic microscopy is one of the most efficient methods for particle tracking as it can precisely measure the axial position of particles. However, imaging systems are often limited by detector noise, image distortions and human operator misjudgment making the particles hard to locate. A general method is used to solve this problem. The normalized holograms of particles were reconstructed to the pupil plane and then fit to a linear superposition of the Zernike polynomial functions to suppress the aberrations. Relative experiments were implemented to validate the method and the results show that nanometer scale resolution was achieved even when the holograms were poorly recorded.

Shape Effects in Nanoparticle-Based Imaging Agents

NASA Astrophysics Data System (ADS)

Culver, Kayla Shani Brook

At the nanoscale, material properties become highly size and shape dependent. These properties can be manipulated and exploited for a variety of biomedical applications, including sensing, drug delivery, diagnostics, and imaging. In particular, nanoparticles of different materials, sizes and shapes have been developed as high-performance contrast agents for optical, electron, and medical imaging. In this thesis, I focus on gold nanoparticles because they are widely used as contrast agents in multiple types of imaging modalities. Additionally, the surface of gold can be readily functionalized with ligands and the structure of the particles can be manipulated to modulate their performance as imaging agents. The properties of nanoparticles can generate contrast directly. For example, the light scattering properties of gold particles can be visualized in optical microscopy, the high electron density of gold produces contrast in electron microscopy, and the x-ray absorption properties of gold can be detected in medical x-ray and computed tomography imaging. Alternatively, the properties of the nanomaterial can be exploited to modulate the signal produced by other molecules that are bound to the particle surface. The light emission of molecular fluorophores can be quenched or dramatically increased by coupling to the optical field enhancements of gold nanoparticles, and the performance of gadolinium (Gd(III))-based magnetic resonance imaging (MRI) contrast agents can be increased by coupling to the rotational motion of nanoparticles. In this dissertation, I focus specifically on how the structure of star-shaped gold particles (nanostars) can be exploited as single-particle optical probes and to dramatically enhance the relaxivity of Gd(III) bound to the surface. Differential interference contrast (DIC) is a type of wide-field diffraction-limited optical microscopy that is commonly used by biologists to image cells without labels. Here, I demonstrate the DIC can be used to characterize complex nanoscale structural features and spectral properties of gold nanostars. Specifically, by evaluating the DIC contrast and image patterns of single nanostars, I distinguished between flat and 3D geometries, identified nanostars with 4-fold symmetry, and determined nanostar orientation. Additionally, in multi-wavelength DIC imaging, an inversion in the contrast could be used to indicate the localized surface plasmon resonance of nanostars with 1 and 2 branches. Next, I used DIC to track the rotational and translational dynamics of functionalized nanostars interacting with live cell membranes. The DNA aptamer ligand on the nanostars specifically targets the transmembrane receptor HER2. I tracked single nanoconstructs over long time scales (˜ 20 minutes per particle, > 80 minutes total) with high temporal resolution (4 fps) and found that analysis of the DIC contrast fluctuations could be used to identify multiple modes of rotational behavior on the cell membrane. I developed MATLAB programs to track the moving nanoconstructs in a dynamic background environment and set up a customized live-cell perfusion chamber that is compatible with the bulky high numerical aperture optics. The combination of the environmental control in the chamber and the low light levels required to visualize single nanostars make this technique optimal for long-term tracking of single nanoconstructs in viable cells. Although nanoparticle size is well-known to influence the relaxivity of Gd(III)-based MRI contrast agents that are attached to the surface, the role of nanoparticle shape was previously unknown. Recently, we discovered that the relaxivity of Gd(III)-conjugated DNA bound to nanostars was three-fold higher than that of analogous spherical nanoconstructs. The relaxivities reached enhancements that were beyond limits that could be explained theoretically by size effects alone. We found that the extremely large enhancements could be explained by elongated water residence times in the second coordination sphere. Here, we investigated in detail how the complex structure of the nanostars mediates these effects. By sorting the nanostars by shape, we found that relaxivity increases with increasing branch number. Thus, we hypothesize that the confinement of the Gd(III)-DNA in the regions of negative surface curvature between branches creates a dense hydrophilic environment that promotes relaxation of second-sphere water molecules. These results demonstrate that shape is a new parameter that can be tuned in the optimization of nanoparticle-based T1 MRI contrast agents. It is important to characterize the potential toxicity of nanomaterials that are intended for use in biomedical applications. Thus, I evaluated the in vivo biodistribution and acute toxicity in rats of gold nanostars functionalized with DNA. As expected for nanoparticles of this size (˜50 nm) and surface charge (negative), the primary clearance mechanism was through the liver and spleen. Importantly, even at the highest dose, no signs of acute toxicity were observed based on hematology, clinical chemistry, and histology, indicating that DNA-coated gold nanostars are highly biocompatible. Additionally, I exploited the high contrast of gold in electron microscopy to track the fate of the nanoconstructs within organs ex vivo. In the liver, the nanoconstructs were sequestered in lysosomes of Kupffer cells. The electron microscopy analysis also indicated that the branched structure of the nanostars was intact even after 2 weeks in the liver, which is important for shape-dependent applications.

Earth observations taken during STS-136

NASA Image and Video Library

1995-07-04

STS071-745-006 (27 June-7 July 1995) --- This view shows a ship track, probably in the northern Pacific Ocean, where a ship has caused clouds to form more thickly directly above the path of this ship. This track is therefore visible even though the ship itself is not. Ship tracks are thought to be caused by particles thrown up into the air by the ship, from smokestack emissions and from water particles generated by the ship moving through the sea. Under favorable weather conditions, water condenses around these particles to form clouds, in this case thicker "popcorn" clouds than already exists in the area. Ongoing studies are attempting to understand this phenomenon better.

Moving Particles Through a Finite Element Mesh

PubMed Central

Peskin, Adele P.; Hardin, Gary R.

1998-01-01

We present a new numerical technique for modeling the flow around multiple objects moving in a fluid. The method tracks the dynamic interaction between each particle and the fluid. The movements of the fluid and the object are directly coupled. A background mesh is designed to fit the geometry of the overall domain. The mesh is designed independently of the presence of the particles except in terms of how fine it must be to track particles of a given size. Each particle is represented by a geometric figure that describes its boundary. This figure overlies the mesh. Nodes are added to the mesh where the particle boundaries intersect the background mesh, increasing the number of nodes contained in each element whose boundary is intersected. These additional nodes are then used to describe and track the particle in the numerical scheme. Appropriate element shape functions are defined to approximate the solution on the elements with extra nodes. The particles are moved through the mesh by moving only the overlying nodes defining the particles. The regular finite element grid remains unchanged. In this method, the mesh does not distort as the particles move. Instead, only the placement of particle-defining nodes changes as the particles move. Element shape functions are updated as the nodes move through the elements. This method is especially suited for models of moderate numbers of moderate-size particles, where the details of the fluid-particle coupling are important. Both the complications of creating finite element meshes around appreciable numbers of particles, and extensive remeshing upon movement of the particles are simplified in this method. PMID:28009377

WE-H-BRA-08: A Monte Carlo Cell Nucleus Model for Assessing Cell Survival Probability Based On Particle Track Structure Analysis

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

Lee, B; Georgia Institute of Technology, Atlanta, GA; Wang, C

Purpose: To correlate the damage produced by particles of different types and qualities to cell survival on the basis of nanodosimetric analysis and advanced DNA structures in the cell nucleus. Methods: A Monte Carlo code was developed to simulate subnuclear DNA chromatin fibers (CFs) of 30nm utilizing a mean-free-path approach common to radiation transport. The cell nucleus was modeled as a spherical region containing 6000 chromatin-dense domains (CDs) of 400nm diameter, with additional CFs modeled in a sparser interchromatin region. The Geant4-DNA code was utilized to produce a particle track database representing various particles at different energies and dose quantities.more » These tracks were used to stochastically position the DNA structures based on their mean free path to interaction with CFs. Excitation and ionization events intersecting CFs were analyzed using the DBSCAN clustering algorithm for assessment of the likelihood of producing DSBs. Simulated DSBs were then assessed based on their proximity to one another for a probability of inducing cell death. Results: Variations in energy deposition to chromatin fibers match expectations based on differences in particle track structure. The quality of damage to CFs based on different particle types indicate more severe damage by high-LET radiation than low-LET radiation of identical particles. In addition, the model indicates more severe damage by protons than of alpha particles of same LET, which is consistent with differences in their track structure. Cell survival curves have been produced showing the L-Q behavior of sparsely ionizing radiation. Conclusion: Initial results indicate the feasibility of producing cell survival curves based on the Monte Carlo cell nucleus method. Accurate correlation between simulated DNA damage to cell survival on the basis of nanodosimetric analysis can provide insight into the biological responses to various radiation types. Current efforts are directed at producing cell survival curves for high-LET radiation.« less

Online Simulation of Radiation Track Structure Project

NASA Technical Reports Server (NTRS)

Plante, Ianik

2015-01-01

Space radiation comprises protons, helium and high charged and energy (HZE) particles. High-energy particles are a concern for human space flight, because they are no known options for shielding astronauts from them. When these ions interact with matter, they damage molecules and create radiolytic species. The pattern of energy deposition and positions of the radiolytic species, called radiation track structure, is highly dependent on the charge and energy of the ion. The radiolytic species damage biological molecules, which may lead to several long-term health effects such as cancer. Because of the importance of heavy ions, the radiation community is very interested in the interaction of HZE particles with DNA, notably with regards to the track structure. A desktop program named RITRACKS was developed to simulate radiation track structure. The goal of this project is to create a web interface to allow registered internal users to use RITRACKS remotely.

Micro-heterogeneity of corn hulls cellulosic fiber biopolymer studied by multiple-particle tracking (MPT)

USDA-ARS?s Scientific Manuscript database

A novel technique named multiple-particle tracking (MPT) was used to investigate the micro-structural heterogeneities of Z-trim, a zero calorie cellulosic fiber biopolymer produced from corn hulls. The principle of MPT technique is to monitor the thermally driven motion of inert micro-spheres, which...

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

Rojas-Herrera, J., E-mail: jimmy06@mit.edu; Rinderknecht, H. G.; Zylstra, A. B.

The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray fluences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-K{sub α} and K{sub β} x-rays. The CR-39 detectors were then exposed to 1–5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those notmore » exposed to x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula.« less

Performance of the ATLAS track reconstruction algorithms in dense environments in LHC Run 2.

PubMed

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Todome, K; Todorova-Nova, S; Tojo, J; Tokár, S; Tokushuku, K; Tolley, E; Tomlinson, L; Tomoto, M; Tompkins, L; Toms, K; Tong, B; Tornambe, P; Torrence, E; Torres, H; Torró Pastor, E; Toth, J; Touchard, F; Tovey, D R; Treado, C J; Trefzger, T; Tresoldi, F; Tricoli, A; Trigger, I M; Trincaz-Duvoid, S; Tripiana, M F; Trischuk, W; Trocmé, B; Trofymov, A; Troncon, C; Trottier-McDonald, M; Trovatelli, M; Truong, L; Trzebinski, M; Trzupek, A; Tsang, K W; Tseng, J C-L; Tsiareshka, P V; Tsipolitis, G; Tsirintanis, N; Tsiskaridze, S; Tsiskaridze, V; Tskhadadze, E G; Tsui, K M; Tsukerman, I I; Tsulaia, V; Tsuno, S; Tsybychev, D; Tu, Y; Tudorache, A; Tudorache, V; Tulbure, T T; Tuna, A N; Tupputi, S A; Turchikhin, S; Turgeman, D; Turk Cakir, I; Turra, R; Tuts, P M; Ucchielli, G; Ueda, I; Ughetto, M; Ukegawa, F; Unal, G; Undrus, A; Unel, G; Ungaro, F C; Unno, Y; Unverdorben, C; Urban, J; Urquijo, P; Urrejola, P; Usai, G; Usui, J; Vacavant, L; Vacek, V; Vachon, B; Vadla, K O H; Vaidya, A; Valderanis, C; Valdes Santurio, E; Valente, M; Valentinetti, S; Valero, A; Valéry, L; Valkar, S; Vallier, A; Valls Ferrer, J A; Van Den Wollenberg, W; van der Graaf, H; van Gemmeren, P; Van Nieuwkoop, J; van Vulpen, I; van Woerden, M C; Vanadia, M; Vandelli, W; Vaniachine, A; Vankov, P; Vardanyan, G; Vari, R; Varnes, E W; Varni, C; Varol, T; Varouchas, D; Vartapetian, A; Varvell, K E; Vasquez, J G; Vasquez, G A; Vazeille, F; Vazquez Schroeder, T; Veatch, J; Veeraraghavan, V; Veloce, L M; Veloso, F; Veneziano, S; Ventura, A; Venturi, M; Venturi, N; Venturini, A; Vercesi, V; Verducci, M; Verkerke, W; Vermeulen, A T; Vermeulen, J C; Vetterli, M C; Viaux Maira, N; Viazlo, O; Vichou, I; Vickey, T; Vickey Boeriu, O E; Viehhauser, G H A; Viel, S; Vigani, L; Villa, M; Villaplana Perez, M; Vilucchi, E; Vincter, M G; Vinogradov, V B; Vishwakarma, A; Vittori, C; Vivarelli, I; Vlachos, S; Vlasak, M; Vogel, M; Vokac, P; Volpi, G; von der Schmitt, H; von Toerne, E; Vorobel, V; Vorobev, K; Vos, M; Voss, R; Vossebeld, J H; Vranjes, N; Vranjes Milosavljevic, M; Vrba, V; Vreeswijk, M; Vuillermet, R; Vukotic, I; Wagner, P; Wagner, W; Wagner-Kuhr, J; Wahlberg, H; Wahrmund, S; Wakabayashi, J; Walder, J; Walker, R; Walkowiak, W; Wallangen, V; Wang, C; Wang, C; Wang, F; Wang, H; Wang, H; Wang, J; Wang, J; Wang, Q; Wang, R; Wang, S M; Wang, T; Wang, W; Wang, W; Wang, Z; Wanotayaroj, C; Warburton, A; Ward, C P; Wardrope, D R; Washbrook, A; Watkins, P M; Watson, A T; Watson, M F; Watts, G; Watts, S; Waugh, B M; Webb, A F; Webb, S; Weber, M S; Weber, S W; Weber, S A; Webster, J S; Weidberg, A R; Weinert, B; Weingarten, J; Weirich, M; Weiser, C; Weits, H; Wells, P S; Wenaus, T; Wengler, T; Wenig, S; Wermes, N; Werner, M D; Werner, P; Wessels, M; Weston, T D; Whalen, K; Whallon, N L; Wharton, A M; White, A S; White, A; White, M J; White, R; Whiteson, D; Whitmore, B W; Wickens, F J; Wiedenmann, W; Wielers, M; Wiglesworth, C; Wiik-Fuchs, L A M; Wildauer, A; Wilk, F; Wilkens, H G; Williams, H H; Williams, S; Willis, C; Willocq, S; Wilson, J A; Wingerter-Seez, I; Winkels, E; Winklmeier, F; Winston, O J; Winter, B T; Wittgen, M; Wobisch, M; Wolf, T M H; Wolff, R; Wolter, M W; Wolters, H; Wong, V W S; Worm, S D; Wosiek, B K; Wotschack, J; Wozniak, K W; Wu, M; Wu, S L; Wu, X; Wu, Y; Wyatt, T R; Wynne, B M; Xella, S; Xi, Z; Xia, L; Xu, D; Xu, L; Yabsley, B; Yacoob, S; Yamaguchi, D; Yamaguchi, Y; Yamamoto, A; Yamamoto, S; Yamanaka, T; Yamatani, M; Yamauchi, K; Yamazaki, Y; Yan, Z; Yang, H; Yang, H; Yang, Y; Yang, Z; Yao, W-M; Yap, Y C; Yasu, Y; Yatsenko, E; Yau Wong, K H; Ye, J; Ye, S; Yeletskikh, I; Yigitbasi, E; Yildirim, E; Yorita, K; Yoshihara, K; Young, C; Young, C J S; Yu, J; Yu, J; Yuen, S P Y; Yusuff, I; Zabinski, B; Zacharis, G; Zaidan, R; Zaitsev, A M; Zakharchuk, N; Zalieckas, J; Zaman, A; Zambito, S; Zanzi, D; Zeitnitz, C; Zemaityte, G; Zemla, A; Zeng, J C; Zeng, Q; Zenin, O; Ženiš, T; Zerwas, D; Zhang, D; Zhang, F; Zhang, G; Zhang, H; Zhang, J; Zhang, L; Zhang, L; Zhang, M; Zhang, P; Zhang, R; Zhang, R; Zhang, X; Zhang, Y; Zhang, Z; Zhao, X; Zhao, Y; Zhao, Z; Zhemchugov, A; Zhou, B; Zhou, C; Zhou, L; Zhou, M; Zhou, M; Zhou, N; Zhu, C G; Zhu, H; Zhu, J; Zhu, Y; Zhuang, X; Zhukov, K; Zibell, A; Zieminska, D; Zimine, N I; Zimmermann, C; Zimmermann, S; Zinonos, Z; Zinser, M; Ziolkowski, M; Živković, L; Zobernig, G; Zoccoli, A; Zou, R; Zur Nedden, M; Zwalinski, L

2017-01-01

With the increase in energy of the Large Hadron Collider to a centre-of-mass energy of 13 [Formula: see text] for Run 2, events with dense environments, such as in the cores of high-energy jets, became a focus for new physics searches as well as measurements of the Standard Model. These environments are characterized by charged-particle separations of the order of the tracking detectors sensor granularity. Basic track quantities are compared between 3.2 fb[Formula: see text] of data collected by the ATLAS experiment and simulation of proton-proton collisions producing high-transverse-momentum jets at a centre-of-mass energy of 13 [Formula: see text]. The impact of charged-particle separations and multiplicities on the track reconstruction performance is discussed. The track reconstruction efficiency in the cores of jets with transverse momenta between 200 and 1600 [Formula: see text] is quantified using a novel, data-driven, method. The method uses the energy loss, [Formula: see text], to identify pixel clusters originating from two charged particles. Of the charged particles creating these clusters, the measured fraction that fail to be reconstructed is [Formula: see text] and [Formula: see text] for jet transverse momenta of 200-400 [Formula: see text] and 1400-1600 [Formula: see text], respectively.

Rosin-Rammler Distributions in ANSYS Fluent

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

Dunham, Ryan Q.

In Health Physics monitoring, particles need to be collected and tracked. One method is to predict the motion of potential health hazards with computer models. Particles released from various sources within a glove box can become a respirable health hazard if released into the area surrounding a glove box. The goal of modeling the aerosols in a glove box is to reduce the hazards associated with a leak in the glove box system. ANSYS Fluent provides a number of tools for modeling this type of environment. Particles can be released using injections into the flow path with turbulent properties. Themore » models of particle tracks can then be used to predict paths and concentrations of particles within the flow. An attempt to understand and predict the handling of data by Fluent was made, and results iteratively tracked. Trends in data were studied to comprehend the final results. The purpose of the study was to allow a better understanding of the operation of Fluent for aerosol modeling for future application in many fields.« less

Electrically tunable lens speeds up 3D orbital tracking

PubMed Central

Annibale, Paolo; Dvornikov, Alexander; Gratton, Enrico

2015-01-01

3D orbital particle tracking is a versatile and effective microscopy technique that allows following fast moving fluorescent objects within living cells and reconstructing complex 3D shapes using laser scanning microscopes. We demonstrated notable improvements in the range, speed and accuracy of 3D orbital particle tracking by replacing commonly used piezoelectric stages with Electrically Tunable Lens (ETL) that eliminates mechanical movement of objective lenses. This allowed tracking and reconstructing shape of structures extending 500 microns in the axial direction. Using the ETL, we tracked at high speed fluorescently labeled genomic loci within the nucleus of living cells with unprecedented temporal resolution of 8ms using a 1.42NA oil-immersion objective. The presented technology is cost effective and allows easy upgrade of scanning microscopes for fast 3D orbital tracking. PMID:26114037

Stochastic dynamics of intermittent pore-scale particle motion in three-dimensional porous media

NASA Astrophysics Data System (ADS)

Morales, V. L.; Dentz, M.; Willmann, M.; Holzner, M.

2017-12-01

A proper understanding of velocity dynamics is key for making transport predictions through porous media at any scale. We study the velocity evolution process from particle dynamics at the pore-scale with particular interest in preasymptotic (non-Fickian) behavior. Experimental measurements from 3-dimensional particle tracking velocimetry are used to obtain Lagrangian velocity statistics for three different types of media heterogeneity. Particle velocities are found to be intermittent in nature, log-normally distributed and non-stationary. We show that these velocity characteristics can be captured with a correlated Ornstein-Uhlenbeck process for a random walk in space that is parameterized from velocity distributions. Our simple model is rigorously tested for accurate reproduction of velocity variability in magnitude and frequency. We further show that it captures exceptionally well the preasymptotic mean and mean squared displacement in the ballistic and superdiffusive regimes, and can be extended to determine if and when Fickian behavior will be reached. Our approach reproduces both preasymptotic and asymptotic transport behavior with a single transport model, demonstrating correct description of the fundamental controls of anomalous transport.

Mixed analytical-stochastic simulation method for the recovery of a Brownian gradient source from probability fluxes to small windows.

PubMed

Dobramysl, U; Holcman, D

2018-02-15

Is it possible to recover the position of a source from the steady-state fluxes of Brownian particles to small absorbing windows located on the boundary of a domain? To address this question, we develop a numerical procedure to avoid tracking Brownian trajectories in the entire infinite space. Instead, we generate particles near the absorbing windows, computed from the analytical expression of the exit probability. When the Brownian particles are generated by a steady-state gradient at a single point, we compute asymptotically the fluxes to small absorbing holes distributed on the boundary of half-space and on a disk in two dimensions, which agree with stochastic simulations. We also derive an expression for the splitting probability between small windows using the matched asymptotic method. Finally, when there are more than two small absorbing windows, we show how to reconstruct the position of the source from the diffusion fluxes. The present approach provides a computational first principle for the mechanism of sensing a gradient of diffusing particles, a ubiquitous problem in cell biology.

Precise 3D Track Reconstruction Algorithm for the ICARUS T600 Liquid Argon Time Projection Chamber Detector

DOE PAGES

Antonello, M.; Baibussinov, B.; Benetti, P.; ...

2013-01-15

Liquid Argon Time Projection Chamber (LAr TPC) detectors offer charged particle imaging capability with remarkable spatial resolution. Precise event reconstruction procedures are critical in order to fully exploit the potential of this technology. In this paper we present a new, general approach to 3D reconstruction for the LAr TPC with a practical application to the track reconstruction. The efficiency of the method is evaluated on a sample of simulated tracks. We present also the application of the method to the analysis of stopping particle tracks collected during the ICARUS T600 detector operation with the CNGS neutrino beam.

Diffusion rate limitations in actin-based propulsion of hard and deformable particles.

PubMed

Dickinson, Richard B; Purich, Daniel L

2006-08-15

The mechanism by which actin polymerization propels intracellular vesicles and invasive microorganisms remains an open question. Several recent quantitative studies have examined propulsion of biomimetic particles such as polystyrene microspheres, phospholipid vesicles, and oil droplets. In addition to allowing quantitative measurement of parameters such as the dependence of particle speed on its size, these systems have also revealed characteristic behaviors such a saltatory motion of hard particles and oscillatory deformation of soft particles. Such measurements and observations provide tests for proposed mechanisms of actin-based motility. In the actoclampin filament end-tracking motor model, particle-surface-bound filament end-tracking proteins are involved in load-insensitive processive insertion of actin subunits onto elongating filament plus-ends that are persistently tethered to the surface. In contrast, the tethered-ratchet model assumes working filaments are untethered and the free-ended filaments grow as thermal ratchets in a load-sensitive manner. This article presents a model for the diffusion and consumption of actin monomers during actin-based particle propulsion to predict the monomer concentration field around motile particles. The results suggest that the various behaviors of biomimetic particles, including dynamic saltatory motion of hard particles and oscillatory vesicle deformations, can be quantitatively and self-consistently explained by load-insensitive, diffusion-limited elongation of (+)-end-tethered actin filaments, consistent with predictions of the actoclampin filament-end tracking mechanism.

Helium-filled soap bubbles tracing fidelity in wall-bounded turbulence

NASA Astrophysics Data System (ADS)

Faleiros, David Engler; Tuinstra, Marthijn; Sciacchitano, Andrea; Scarano, Fulvio

2018-03-01

The use of helium-filled soap bubbles (HFSB) as flow tracers for particle image velocimetry (PIV) and particle tracking velocimetry (PTV) to measure the properties of turbulent boundary layers is investigated in the velocity range from 30 to 50 m/s. The experiments correspond to momentum thickness-based Reynolds numbers of 3300 and 5100. A single bubble generator delivers nearly neutrally buoyant HFSB to seed the air flow developing over the flat plate. The HFSB motion analysis is performed by PTV using single-frame multi-exposure recordings. The measurements yield the local velocity and turbulence statistics. Planar two-component-PIV measurements with micron-sized droplets (DEHS) conducted under the same conditions provide reference data for the quantities of interest. In addition, the behavior of air-filled soap bubbles is studied where the effect of non-neutral buoyancy is more pronounced. The mean velocity profiles as well as the turbulent stresses obtained with HFSB are in good agreement with the flow statistics obtained with DEHS particles. The study illustrates that HFSB tracers can be used to determine the mean velocity and the turbulent fluctuations of turbulent boundary layers above a distance of approximately two bubble diameters from the wall. This work broadens the current range of application of HFSB from external aerodynamics of large-scale-PIV experiments towards wall-bounded turbulence.

Genetic Correlation with the DNA Repair Assay in Mice Exposed to High-LET

NASA Technical Reports Server (NTRS)

Penninckx, Sebastien; Ray, Shayoni; Degorre, Charlotte; Guiet, Elodie; Viger, Louise; Pluth, Janice; Snijders, Antoine; Mao, Jian-Hua; Costes, Sylvain V.

2017-01-01

We hypothesize that DNA damage induced by high local energy deposition, occurring when cells are traversed by high-LET (Linear Energy Transfer) particles, can be experimentally modeled by exposing cells to high doses of low-LET. In this work, we validate such hypothesis by characterizing and correlating the time dependence of 53BP1 radiation-induced foci (RIF) for various doses and LET across 72 primary skin fibroblast from mice. This genetically diverse population allows us to understand how genetic may modulate the dose and LET relationship. The cohort was made on average from 3 males and 3 females belonging to 15 different strains of mice with various genetic backgrounds, including the collaborative cross (CC) genetic model (10 strains) and 5 reference mice strains. Cells were exposed to two fluences of three HZE (High Atomic Energy) particles (Si 350 megaelectronvolts per nucleon, Ar 350 megaelectronvolts per nucleon and Fe 600 megaelectronvolts per nucleon) and to 0.1, 1 and 4 grays from a 160 kilovolt X-ray. Individual radiation sensitivity was investigated by high throughput measurements of DNA repair kinetics for different doses of each radiation type. The 53BP1 RIF dose response to high-LET particles showed a linear dependency that matched the expected number of tracks per cell, clearly illustrating the fact that close-by DNA double strand breaks along tracks cluster within one single RIF. By comparing the slope of the high-LET dose curve to the expected number of tracks per cell we computed the number of remaining unrepaired tracks as a function of time post-irradiation. Results show that the percentage of unrepaired track over a 48 hours follow-up is higher as the LET increases across all strains. We also observe a strong correlation between the high dose repair kinetics following exposure to 160 kilovolts X-ray and the repair kinetics of high-LET tracks, with higher correlation with higher LET. At the in-vivo level for the 10-CC strains, we observe that drops in the number of T-cells and B-cells found in the blood of mice 24 hours after exposure to 0.1 gray of 320 kilovolts X-ray correlate well with slower DNA repair kinetics in skin cells exposed to X-ray. Overall, our results suggest that repair kinetics found in skin is a surrogate marker for in-vivo radiation sensitivity in other tissue, such as blood cells, and that such response is modulated by genetic variability.

Tackling Production Techniques: Professional Studio Sound at Amateur Prices: the Power of the Portable Four-Track Audio Recorder.

ERIC Educational Resources Information Center

Robinson, David E.

1997-01-01

One solution to poor quality sound in student video projects is a four-track audio cassette recorder. This article discusses the advantages of four-track over single-track recorders and compares two student productions, one using a single-track and the other a four-track recorder. (PEN)

Imaging of cellular spread on a three-dimensional scaffold by means of a novel cell-labeling technique for high-resolution computed tomography.

PubMed

Thimm, Benjamin W; Hofmann, Sandra; Schneider, Philipp; Carretta, Roberto; Müller, Ralph

2012-03-01

Computed tomography (CT) represents a truly three-dimensional (3D) imaging technique that can provide high-resolution images on the cellular level. Thus, one approach to detect single cells is X-ray absorption-based CT, where cells are labeled with a dense, opaque material providing the required contrast for CT imaging. Within the present work, a novel cell-labeling method has been developed showing the feasibility of labeling fixed cells with iron oxide (FeO) particles for subsequent CT imaging and quantitative morphometry. A biotin-streptavidin detection system was exploited to bind FeO particles to its target endothelial cells. The binding of the particles was predominantly close to the cell centers on 2D surfaces as shown by light microscopy, scanning electron microscopy, and CT. When cells were cultured on porous, 3D polyurethane surfaces, significantly more FeO particles were detected compared with surfaces without cells and FeO particle labeling using CT. Here, we report on the implementation and evaluation of a novel cell detection method based on high-resolution CT. This system has potential in cell tracking for 3D in vitro imaging in the future.

Filling of a Poisson trap by a population of random intermittent searchers.

PubMed

Bressloff, Paul C; Newby, Jay M

2012-03-01

We extend the continuum theory of random intermittent search processes to the case of N independent searchers looking to deliver cargo to a single hidden target located somewhere on a semi-infinite track. Each searcher randomly switches between a stationary state and either a leftward or rightward constant velocity state. We assume that all of the particles start at one end of the track and realize sample trajectories independently generated from the same underlying stochastic process. The hidden target is treated as a partially absorbing trap in which a particle can only detect the target and deliver its cargo if it is stationary and within range of the target; the particle is removed from the system after delivering its cargo. As a further generalization of previous models, we assume that up to n successive particles can find the target and deliver its cargo. Assuming that the rate of target detection scales as 1/N, we show that there exists a well-defined mean-field limit N→∞, in which the stochastic model reduces to a deterministic system of linear reaction-hyperbolic equations for the concentrations of particles in each of the internal states. These equations decouple from the stochastic process associated with filling the target with cargo. The latter can be modeled as a Poisson process in which the time-dependent rate of filling λ(t) depends on the concentration of stationary particles within the target domain. Hence, we refer to the target as a Poisson trap. We analyze the efficiency of filling the Poisson trap with n particles in terms of the waiting time density f(n)(t). The latter is determined by the integrated Poisson rate μ(t)=∫(0)(t)λ(s)ds, which in turn depends on the solution to the reaction-hyperbolic equations. We obtain an approximate solution for the particle concentrations by reducing the system of reaction-hyperbolic equations to a scalar advection-diffusion equation using a quasisteady-state analysis. We compare our analytical results for the mean-field model with Monte Carlo simulations for finite N. We thus determine how the mean first passage time (MFPT) for filling the target depends on N and n.

An in-silico walker

NASA Astrophysics Data System (ADS)

Xiao, Qiran; Chen, Yanping; Bereau, Tristan; Shi, Yunfeng

2016-08-01

The paradox of biomimetic research is to perform bio-functionality, usually associated with sophisticated structures optimized by nature, with minimal structural complexity for the ease of fabrication. Here we show that a three-particle trimer can exhibit kinesin-like autonomous walk on a track via reactive molecular dynamics simulations. The autonomous motion is due to imbalanced transitions resulting from exothermic catalytic reactions, and the spatial asymmetry from the track. This molecular design can be realized by reproducing the particle-particle interactions in functionalized nano- or colloidal particles. Our results open up the possibility of fabricating bio-mimetic nano-systems in a minimalist approach.

Digital holographic diagnostics of near-injector region

NASA Astrophysics Data System (ADS)

Lee, Jaiho

Study of primary breakup of liquid jets is important because it is motivated by the application to gas turbine fuel injectors, diesel fuel injectors, industrial cleaning and washing machine, medical spray, and inkjet printers, among others. When it comes to good injectors, a liquid jet has to be disintegrated into a fine spray near injector region during primary breakup. However the dense spray region near the injectors is optically obscure for Phase Doppler Interferometer like Phase Doppler Particle Analyzers (PDPA). Holography can provide three dimensional image of the dense spray and eliminate the problem of the small depth of focus associated with shadowgraphs. Traditional film-based holographic technique has long been used for three dimensional measurements in particle fields, but it is time consuming, expensive, chemically hazardous. With the development of the CCD sensor, holograms were recorded and reconstructed digitally. Digital microscopic holography (DMH) is similar to digital inline holography (DIH) except that no lens is used to collimate the object beam. The laser beams are expanded with an objective lens and a spatial filter. This eliminates two lenses from the typical optical path used for in-line holography, which results in a much cleaner hologram recording. The DMH was used for drop size and velocity measurements of the breakup of aerated liquid jets because it is unaffected by the non-spherical droplets that are encountered very close to the injector exit, which would cause problems for techniques such as Phase Doppler Particle Analyzer, otherwise. Large field of view was obtained by patching several high resolution holograms. Droplet velocities in three dimensions were measured by tracking their displacements in the streamwise and cross-stream direction and by tracking the change in the plane of focus in the spanwise direction. The uncertainty in spanwise droplet location and velocity measurements using single view DMH was large at least 33%. This large uncertainty in the spanwise direction, however, can be reduced to 2% by employing double view DMH. Double view DMH successfully tracked the three dimensional bending trajectories of polymer jets during electrospinning. The uncertainty in the spatial growth measurements of the bending instability was reduced using orthogonal double view DMH. Moreover, a commercial grade CCD was successfully used for single- and double-pulsed DMH of micro liquid jet breakup. Using a commercial grade CCD for the DMH, the cost of CCD sensor needed for recording holograms can be reduced.

Exploration of thermal counterflow in He II using particle tracking velocimetry

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

Mastracci, Brian; Guo, Wei

Flow visualization using particle image velocimetry (PIV) and particularly particle tracking velocimetry (PTV) has been applied to thermal counterflow in He II for nearly two decades now, but the results remain difficult to interpret because tracer particle motion can be influenced by both the normal fluid and superfluid components of He II as well as the quantized vortex tangle. For instance, in one early experiment it was observed (using PTV) that tracer particles move at the normal fluid velocity v n, while in another it was observed (using PIV) that particles move at v n/2. Besides the different visualization methods,more » the range of applied heat flux investigated by these experiments differed by an order of magnitude. To resolve this apparent discrepancy and explore the statistics of particle motion in thermal counterflow, we apply the PTV method to a wide range of heat flux at a number of different fluid temperatures. In our analysis, we introduce a scheme for analyzing the velocity of particles presumably moving with the normal fluid separately from those presumably influenced by the quantized vortex tangle. Our results show that for lower heat flux there are two distinct peaks in the streamwise particle velocity probability density function (PDF), with one centered at the normal fluid velocity v n (named G2 for convenience) while the other is centered near v n/2 (G1). For higher heat flux there is a single peak centered near v n/2 (G3). Using our separation scheme, we show quantitatively that there is no size difference between the particles contributing to G1 and G2. We also show that nonclassical features of the transverse particle velocity PDF arise entirely from G1, while the corresponding PDF for G2 exhibits the classical Gaussian form. The G2 transverse velocity fluctuation, backed up by second sound attenuation in decaying counterflow, suggests that large-scale turbulence in the normal fluid is absent from the two-peak region. We offer a brief discussion of the physical mechanisms that may be responsible for our observations, revealing that G1 velocity fluctuations may be linked to fluctuations of quantized vortex line velocity, and suggest a number of numerical simulations that may reveal the underlying physics in detail.« less

Exploration of thermal counterflow in He II using particle tracking velocimetry

DOE PAGES

Mastracci, Brian; Guo, Wei

2018-06-22

Flow visualization using particle image velocimetry (PIV) and particularly particle tracking velocimetry (PTV) has been applied to thermal counterflow in He II for nearly two decades now, but the results remain difficult to interpret because tracer particle motion can be influenced by both the normal fluid and superfluid components of He II as well as the quantized vortex tangle. For instance, in one early experiment it was observed (using PTV) that tracer particles move at the normal fluid velocity v n, while in another it was observed (using PIV) that particles move at v n/2. Besides the different visualization methods,more » the range of applied heat flux investigated by these experiments differed by an order of magnitude. To resolve this apparent discrepancy and explore the statistics of particle motion in thermal counterflow, we apply the PTV method to a wide range of heat flux at a number of different fluid temperatures. In our analysis, we introduce a scheme for analyzing the velocity of particles presumably moving with the normal fluid separately from those presumably influenced by the quantized vortex tangle. Our results show that for lower heat flux there are two distinct peaks in the streamwise particle velocity probability density function (PDF), with one centered at the normal fluid velocity v n (named G2 for convenience) while the other is centered near v n/2 (G1). For higher heat flux there is a single peak centered near v n/2 (G3). Using our separation scheme, we show quantitatively that there is no size difference between the particles contributing to G1 and G2. We also show that nonclassical features of the transverse particle velocity PDF arise entirely from G1, while the corresponding PDF for G2 exhibits the classical Gaussian form. The G2 transverse velocity fluctuation, backed up by second sound attenuation in decaying counterflow, suggests that large-scale turbulence in the normal fluid is absent from the two-peak region. We offer a brief discussion of the physical mechanisms that may be responsible for our observations, revealing that G1 velocity fluctuations may be linked to fluctuations of quantized vortex line velocity, and suggest a number of numerical simulations that may reveal the underlying physics in detail.« less

Ultra-high-speed 3D astigmatic particle tracking velocimetry: application to particle-laden supersonic impinging jets

NASA Astrophysics Data System (ADS)

Buchmann, N. A.; Cierpka, C.; Kähler, C. J.; Soria, J.

2014-11-01

The paper demonstrates ultra-high-speed three-component, three-dimensional (3C3D) velocity measurements of micron-sized particles suspended in a supersonic impinging jet flow. Understanding the dynamics of individual particles in such flows is important for the design of particle impactors for drug delivery or cold gas dynamic spray processing. The underexpanded jet flow is produced via a converging nozzle, and micron-sized particles ( d p = 110 μm) are introduced into the gas flow. The supersonic jet impinges onto a flat surface, and the particle impact velocity and particle impact angle are studied for a range of flow conditions and impingement distances. The imaging system consists of an ultra-high-speed digital camera (Shimadzu HPV-1) capable of recording rates of up to 1 Mfps. Astigmatism particle tracking velocimetry (APTV) is used to measure the 3D particle position (Cierpka et al., Meas Sci Technol 21(045401):13, 2010) by coding the particle depth location in the 2D images by adding a cylindrical lens to the high-speed imaging system. Based on the reconstructed 3D particle positions, the particle trajectories are obtained via a higher-order tracking scheme that takes advantage of the high temporal resolution to increase robustness and accuracy of the measurement. It is shown that the particle velocity and impingement angle are affected by the gas flow in a manner depending on the nozzle pressure ratio and stand-off distance where higher pressure ratios and stand-off distances lead to higher impact velocities and larger impact angles.

A highly scalable particle tracking algorithm using partitioned global address space (PGAS) programming for extreme-scale turbulence simulations

NASA Astrophysics Data System (ADS)

Buaria, D.; Yeung, P. K.

2017-12-01

A new parallel algorithm utilizing a partitioned global address space (PGAS) programming model to achieve high scalability is reported for particle tracking in direct numerical simulations of turbulent fluid flow. The work is motivated by the desire to obtain Lagrangian information necessary for the study of turbulent dispersion at the largest problem sizes feasible on current and next-generation multi-petaflop supercomputers. A large population of fluid particles is distributed among parallel processes dynamically, based on instantaneous particle positions such that all of the interpolation information needed for each particle is available either locally on its host process or neighboring processes holding adjacent sub-domains of the velocity field. With cubic splines as the preferred interpolation method, the new algorithm is designed to minimize the need for communication, by transferring between adjacent processes only those spline coefficients determined to be necessary for specific particles. This transfer is implemented very efficiently as a one-sided communication, using Co-Array Fortran (CAF) features which facilitate small data movements between different local partitions of a large global array. The cost of monitoring transfer of particle properties between adjacent processes for particles migrating across sub-domain boundaries is found to be small. Detailed benchmarks are obtained on the Cray petascale supercomputer Blue Waters at the University of Illinois, Urbana-Champaign. For operations on the particles in a 81923 simulation (0.55 trillion grid points) on 262,144 Cray XE6 cores, the new algorithm is found to be orders of magnitude faster relative to a prior algorithm in which each particle is tracked by the same parallel process at all times. This large speedup reduces the additional cost of tracking of order 300 million particles to just over 50% of the cost of computing the Eulerian velocity field at this scale. Improving support of PGAS models on major compilers suggests that this algorithm will be of wider applicability on most upcoming supercomputers.